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Faculty Seminar

Date:
17
Wednesday
August
2022
Lecture / Seminar
Time: 10:30-11:30
Title: Data Crimes: The Risk in Naive Training of Medical AI Algorithms
Location: Jacob Ziskind Building
Lecturer: Efrat Shimron
Organizer: Department of Computer Science and Applied Mathematics
Abstract: Although open-access databases are an important resource in the current deep lea ... Read more Although open-access databases are an important resource in the current deep learning (DL) era, they are sometimes used in an "off label" manner: data published for one task are used during training of algorithms for a different task. In this seminar I will show that this leads to biased, overly optimistic results of well-known inverse problem solvers, focusing on algorithms developed for magnetic resonance imaging (MRI) reconstruction. I will show that when such algorithms are trained using off-label data, they yield biased results, with up to 48% artificial improvement. The underlying cause is that public databases are often preprocessed using hidden pipelines, which change the data features and improve the inverse problem conditioning. My work shows that canonical algorithms - Compressed Sensing, Dictionary Learning, and Deep Learning algorithms - are all prone to this form of bias. Furthermore, once trained, these algorithms exhibit poor generalization to real-world data, thus they could produce unreliable results in clinical setups. To raise awareness to the growing problem of naive use of public data and the associated biased results, the term "data crimes" is coined.
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The annual IsSDB symposium: Imaging development

Date:
08
Thursday
December
2022
Conference
Time: 08:00
Location: David Lopatie Conference Centre

EMIM 2021 European Society for Molecular Imaging

Date:
12
Sunday
March
2023
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16
Thursday
March
2023
Conference
Time: 08:00
Location: Michael Sela Adutitorium
Organizer: Department of Immunology and Regenerative Biology

    Past

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    Emergent collective coding properties in hippocampal neuronal population activity

    Date:
    01
    Monday
    August
    2022
    Lecture / Seminar
    Time: 13:00-14:00
    Title: Student Seminar-PhD Thesis Defense HYBRID
    Location: Nella and Leon Benoziyo Building for Brain Research
    Lecturer: Liron Sheintuch
    Organizer: Department of Brain Sciences
    Details: Link:https://weizmann.zoom.us/j/97167587409?pwd=TDFFYWI0ZmF5YXk0TW5oN1ZKSStndz09 ... Read more Link:https://weizmann.zoom.us/j/97167587409?pwd=TDFFYWI0ZmF5YXk0TW5oN1ZKSStndz09 Meeting ID: 971 6758 7409 Password: 227875 Benoziyo Brain Research Building Room 113
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    Abstract: Populations of hippocampal neurons have been hypothesized to operate collectivel ... Read more Populations of hippocampal neurons have been hypothesized to operate collectively to support the stable maintenance of long-term memories. To test this hypothesis, we performed large-scale calcium imaging in the hippocampus of freely behaving mice that repeatedly explored the same environments over weeks. Surprisingly, we discovered that across separate visits to the same familiar environment, hippocampal neurons can collectively switch between multiple distinct spatial representations, without any apparent changes in sensory input or animal’s behavior. The distinct representations were spatially informative and stable over weeks, and switching between them required a complete disconnection of the animal from the environment, demonstrating the coexistence of distinct stable attractors in the hippocampal network. In the second part of the talk, I will present a comparison of the coding properties between hippocampal subfields CA1 and CA3 in novel environments. Place cells in CA3 had more precise and stable spatial tuning than place cells in CA1. Moreover, we showed that in CA3 the tuning of place cells exhibited a higher statistical dependence with their peers compared to in CA1, uncovering an organization of CA3 into cell assemblies. Interestingly, cells with stronger tuning peer-dependence had higher stability but not higher precision, suggesting that distinct mechanisms control these two aspects of the neural code. Overall, our results demonstrate that multiple attractor states can stably coexist in the hippocampus and suggest that a cell-assembly organization in hippocampal CA3 underlies the long-term maintenance of stable spatial codes. Link:https://weizmann.zoom.us/j/97167587409?pwd=TDFFYWI0ZmF5YXk0TW5oN1ZKSStndz09 Meeting ID: 971 6758 7409 Password: 227875
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    Ph.D thesis: Pushing the envelope of high field DNP-NMR methodology towards functional materials

    Date:
    20
    Wednesday
    July
    2022
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Asya Svirinovsky
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Functional materials are the main building blocks of advanced technologies based ... Read more Functional materials are the main building blocks of advanced technologies based on energy storage and conversion systems essential for our modern life including batteries, solar cells, and heterogeneous catalysis. Improvements in materials performance and development of new materials rely on our ability to obtain structure-function correlation as well as understand degradation processes when the materials are integrated into a device. To this end, advanced analytical tools that can provide information at the atomic level are essential. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy is well suited for this task, especially when equipped with high sensitivity by Magic Angle Spinning - Dynamic Nuclear Polarization (MAS-DNP). However, to date, the majority of materials studied by MAS-DNP were non-reactive and non-conductive materials with DNP from exogenous sources of polarization such as nitroxide radicals. This approach cannot be simply extended to functional materials as the properties that stem from the material’s functionality in the device, including electrical conductivity, chemical reactivity and defects, often pose challenges in the study of the materials by DNP. In this talk I will frame the challenges associated with the application of MAS-DNP to functional materials and describe approaches to address them. Results will be presented from three ubiquitous material systems spanning a range of applications: carbon allotropes, transition metal dichalcogenides (TMDs) and metallic microstructures. We systematically investigated the deleterious effect of materials’ conductivity and formulated means to reduce the effect. We explored the feasibility of utilizing inherent unpaired electrons for endogenous DNP and applied it to probe buried phases in all-solid-state lithium-metal battery and the surface chemistry in carbons. I will show that wealth of information achieved by DNP on various functional materials, can place DNP-NMR as a preferable tool for materials scientists. Our findings are expected to apply to many other systems where functional materials are dominant, making DNP a more general technique.
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    Special guest semianr with Dr. Asaf Zviran

    Date:
    17
    Sunday
    July
    2022
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Ultra-sensitive detection and monitoring of solid cancers using whole-genome mutation integration
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Asaf Zviran
    Organizer: Azrieli Institute for Systems Biology
    Abstract: Early detection of recurrence and monitoring of Molecular Residual Disease (MRD) ... Read more Early detection of recurrence and monitoring of Molecular Residual Disease (MRD) post-surgery is critical for clinical decision-making to tailor personalized treatments across solid cancers. C2i Genomics has developed an ultra-sensitive whole-genome ctDNA test, allowing extremely accurate and sensitive monitoring of patients with solid tumors. Here we present results from applying whole-genome sequencing (WGS) and identification of ctDNA across a variety of adult and pediatric solid tumors. We integrate a genome-wide mutation and copy number monitoring approach coupled with advanced signal processing and Artificial Intelligence (AI) for measuring the tumor load from low-input blood samples (~1mL of plasma) with ultra-sensitive detection. The increased sensitivity allowed clinical detection of tumor fraction down to 5*10-5 and recurrence detection sensitivity achieving >65% at the first two months after definitive treatment, enabling earlier clinical intervention for high-risk patients.
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    “Aspects of solar cell operation and reliability in High and low dimensions”

    Date:
    06
    Wednesday
    July
    2022
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Jean Francois Guillemoles
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: The development of advanced photovoltaic devices, including those that might ove ... Read more The development of advanced photovoltaic devices, including those that might overcome the single junction efficiency limit, as well as the development of new materials, all rely on advanced characterization methods. Among all the existing methods optically based ones are very well adapted to quantitatively probe optoelectronic properties at any stage. We here present the use of multidimensional imaging techniques that record spatially, spectrally and time resolved luminescence images. We will discuss the benefits (and challenges) of looking into energy conversion systems from high dimensions perspective and those of dimensional reduction for improved intelligibility through some examples, mostly drawn from halide perovskite materials and device. These examples will help visit questions related to efficient transport and conversion in solar cells, as well as questions related to chemical and operational stability of the devices.
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    Using functional MRI to better understand neurodevelopmental disorders and to find biomarkers of treatment response in mental illness

    Date:
    05
    Tuesday
    July
    2022
    Lecture / Seminar
    Time: 12:30-13:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Keith Shafritz
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Michal Ramot michal.ramot@weizmann.ac.il tel:4417
    Abstract: Our ability to correctly diagnose and treat mental illness is limited by the ove ... Read more Our ability to correctly diagnose and treat mental illness is limited by the overlap in symptoms of many disorders, despite differing etiology. Determining the proper course of treatment is quite difficult because treating individual symptoms does not always lead to successful remission and typically involves a trial-and-error approach. Task-based functional MRI has become a highly useful tool for determining the brain regions involved in cognition and behavior in humans, with the potential to be used to find biomarkers of mental illness and treatment outcomes. Much of the research in this domain has focused on the differences in brain activation between groups of individuals with specific mental disorders and typically developing “control” groups. However, by relating brain activation patterns of clinical groups to symptom severity, developmental processes, and response to treatment at the individual level, we can determine brain-based markers that have the potential to be used as diagnostic tools in the future and to determine whether certain treatments would be helpful based on specific brain activation patterns. In this talk, I will present data from studies using task-based functional MRI in autism spectrum disorder, schizophrenia, and childhood adversity that illustrate the potential of this technology for diagnostic and treatment purposes. I will also discuss the promises and limitations of using fMRI as a clinical tool.
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    Advanced Concepts of Super-Resolution Fluorescence Microscopy

    Date:
    04
    Monday
    July
    2022
    Colloquium
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Joerg Enderlein
    Organizer: Faculty of Chemistry
    Abstract: With the advent of super-resolution microscopy, the last ~25 years have seen a r ... Read more With the advent of super-resolution microscopy, the last ~25 years have seen a revolution in optical microscopy, pushing the spatial resolution capabilities of optical microscopy towards length scales that were typically accessible only by electron microscopy. In my presentation, I will give a short overview of the different principal approaches to super-resolution microscopy. I will briefly discuss the concepts of Structured Illumination Microscopy (SIM), Stimulated Emission Depletion (STED) microscopy, and Single Molecule Localization Microscopy (SMLM). Then, I will focus on two specific techniques where our group has contributed most. The first is Image Scanning Microscopy or ISM [1-3]. This technique uses a simple combination of confocal microscopy with wide-field image detection for doubling the resolution of conventional microscopy. I will explain the physical principals behind ISM, and the various kinds of its implementation. Meanwhile, ISM has found broad and wide applications and lies behind state-of-the-art commercial systems such as the extremely successful AiryScan microscope from Carl Zeiss Jena. The second method is Super-resolution Optical Fluctuation Imaging (SOFI), which uses the stochastic blinking of emitters for overcoming the classical diffraction limit of resolution, similar to single-molecule localization microscopy, but with much relaxed demands on blinking behavior and label density [4]. The third method is Metal-Induced Energy Transfer imaging or MIET imaging [5-6]. It addresses the axial resolution in microscopy, which is particularly important for resolving three-dimensional structures. MIET is based on the intricate electrodynamic interaction of fluorescent emitters with metallic nanostructures. I will present the basic principles and several applications of this technique.
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    Physics Hybrid Colloquium

    Date:
    30
    Thursday
    June
    2022
    Colloquium
    Time: 11:15-12:30
    Title: The construction of the Vera Rubin Observatory and cosmological measurements of dark matter and dark energy with LSST
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Zeljko Ivesic
    Organizer: Faculty of Physics
    Details: 11:00 - Coffee, tea and more...
    Abstract: The Legacy Survey of Space and Time (LSST), the first project to be undertaken ... Read more The Legacy Survey of Space and Time (LSST), the first project to be undertaken at the new Vera Rubin Observatory, will be the most comprehensive optical astronomical survey ever undertaken. Starting in 2024, Rubin Observatory will obtain panoramic images covering the sky visible from its location in Chile every clear night for ten years. The resulting hundreds of petabytes of imaging data, essentially a digital color movie of the night sky, will include about 40 billion stars and galaxies, and will be used for investigations ranging from cataloging dangerous near-Earth asteroids to fundamental physics such as characterization of dark matter and dark energy. I will start my presentation with an overview of LSST science drivers and system design, and continue with a construction status report for the Vera Rubin Observatory. I will conclude with a brief discussion of a few Big Data challenges that need to be addressed before LSST data can be used for precise cosmological measurements.
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    Molecular design of solid catalysts

    Date:
    29
    Wednesday
    June
    2022
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Alexander Katz
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: This colloquium will be divided into two applications parts, dealing with synthe ... Read more This colloquium will be divided into two applications parts, dealing with synthesis of supported molecular catalysts and solid catalysts for photoprotection. In the first of these areas, we describe a mechanical approach for stabilizing supported weakly interacting active sites (i.e. those that interact non-covalently with the support) against aggregation and coalescence. We use silica as a prototypical example of a support, and an iridium pair-site catalyst incorporating bridging calixarene ligands as an active site. Atomic-resolution imaging of the Ir centers before and after ethylene-hydrogenation catalysis show the metals resisted aggregation and deactivation, remaining atomically dispersed and accessible for catalysis. When active sites are located at unconfined environments, the rate constants for ethylene hydrogenation are markedly lower compared with confining external-surface pockets [1], in line with prior observations of similar effects in olefin epoxidation catalysis [2,3]. Altogether, these examples represent new opportunities for enhancing reactivity on surfaces by synthetically controlling mechanical features of active site catalyst environments. In the second of these areas, reactive oxygen species (ROS) are associated with several human health pathologies and are invoked in the degradation of natural ecosystems as well as building materials that are used in modern infrastructure (e.g., paints and coatings, polymers, etc). Natural antioxidants such as vitamin E function as stoichiometric reductants (i.e. reaction with ROS synthesizes rancid oils). While enzymes such as superoxide dismutase working in tandem with catalase decompose decompose ROS to H2O and O2 through H2O2 as an intermediate, these enzymes are fragile and costly. Other non-stoichiometric commercial antioxidants that degrade ROS include hindered amine light stabilizers (HALS). Here, we demonstrate that cerium carbonate acts as a degradation catalyst for photogenerated ROS, and describe the performance and characterization of this new catalyst using X-ray photoelectron spectroscopy, and in comparison with HALS and stoichiometric reductants. Our results demonstrate catalytic antioxidant activity of cerium carbonate when dispersed in polymethylmethacrylate polymer. FTIR data demonstrate that a dispersion of 2 wt. % cerium carbonate within the polymer essentially stops degradation by photogenerated ROS, which otherwise cause oxidation of the polymer backbone, in the control polymer lacking cerium carbonate. Experiments with methylene blue dye in aqueous solution demonstrate that cerium carbonate decreases the rate of ROS degradation of dye, in the presence of UV irradiation and air by 16 fold. These effects become even more pronounced (over 600 fold decrease in rate of ROS dye degradation) when cerium carbonate is paired with a photoactive metal oxide. The mechanism involved in this latter case crudely mimics the enzyme tandem sequence referred to above. [1] C. Schöttle, E. Guan, A. Okrut, N. A. Grosso-Giordano, A. Palermo, A. Solovyov, B. C. Gates, A. Katz*, Journal of the American Chemical Society, J. Am. Chem. Soc. 2019, 141, 4010-4015. [2] N. A. Grosso-Giordano, C. Schroeder, A. Okrut, A. Solovyov, C. Schottle, W. Chasse, N. Marinkoyic, H. Koller, S. I. Zones, A. Katz, Journal of the American Chemical Society 2018, 140, 4956-4960. [3] N. A. Grosso-Giordano, A. S. Hoffman, A. Boubnov, D. W. Small, S. R. Bare, S. I. Zones, A. Katz, Journal of the American Chemical Society 2019, 141, 7090-7106. [4] M. K. Mishra, J. Callejas, M. Pacholski, J. Ciston, A. Okrut, A. Van Dyk, D. Barton, J. C. Bohling, A. Katz, ACS Applied Nano Materials 2021, 4, 11, 11590-11600.
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    Genetic Factors & Long Range Circuit Dynamics Underlying Memory Processing-ZOOM

    Date:
    28
    Tuesday
    June
    2022
    Lecture / Seminar
    Time: 15:00-16:00
    Lecturer: Prof. Priya Rajasethupathy
    Organizer: Department of Brain Sciences
    Details: Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeH ... Read more Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421
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    Abstract: How do fleeting molecules and dynamic neural codes enable the conversion of tr ... Read more How do fleeting molecules and dynamic neural codes enable the conversion of transient stimuli into lasting internal representations? And are there unique strategies to achieve memory on different time scales. Our lab addresses these questions by bridging functional genomics with systems neuroscience to provide cross-disciplinary insights. On one hand, we perform genetic mapping in outbred mice for unbiased discovery of genes, cell types, and circuits relevant for memory across different time scales. In parallel, we develop and apply methodologies to record and manipulate high resolution neural activity from these relevant circuits in the behaving animal. In today’s talk, I will discuss how these approaches have led to new insights into the genetic contributions and long-range circuit dynamics that facilitate both short- and long- term memory.  Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421
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    Special guest seminar with Dr. Or Shemesh

    Date:
    28
    Tuesday
    June
    2022
    Lecture / Seminar
    Time: 09:30-10:30
    Title: Infectious Neuroscience - Do Common Pathogens Play a Part in Neurodegeneration?
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Or Shemesh
    Organizer: Department of Molecular Neuroscience
    Abstract: Herpes Simplex Virus 1 (HSV-1) is a usual suspect when it comes to Alzheimer's d ... Read more Herpes Simplex Virus 1 (HSV-1) is a usual suspect when it comes to Alzheimer's disease (AD), and its DNA and RNA were found in the brains and serological samples of AD patients. Such molecular presence of HSV-1 in AD is especially intriguing as HSV-1 virions are rarely detected in AD brains. To follow the molecular footsteps detected, we imaged viral proteins in postmortem human AD brains at superior resolution using expansion microscopy, a tissue manipulation method that physically expands the samples by a factor of 4.5x, allowing a 40 nm imaging resolution, and immunolabeled herpetic proteins, AD pathologies and cell markers. We found an abundance of herpetic proteins, previously undetectable with standard methods, across large brain areas. Importantly, we found that HSV-1 proteins strongly co-localized with AD pathologies. Consequently, we hypothesized that expression of HSV-1 proteins during latency may be linked to AD pathology. We are now in the process of characterizing the HSV-1 proteome in AD brains by imaging key proteins in expanded AD brain slices and examining their colocalization with AD pathologies across brain areas and disease stages. As a complementary system to the fixed human brain slices, we are exposing live human brain organoids, to HSV-1, and imaging the relationships between viral proteins and the formation of AD pathologies via expansion microscopy. Pathogens may be triggers of immune responses driving AD; this study would shed light on one common pathogen, HSV-1, while serving as a framework to unveiling molecular causation between infectious agents and AD hallmarks.
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    Sugar: A gut choice

    Date:
    21
    Tuesday
    June
    2022
    Lecture / Seminar
    Time: 12:30-13:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Diego V. Bohórquez, Ph.D.
    Organizer: Department of Brain Sciences
    Abstract: Animals distinguish sugars from non-nutritive sweeteners even in the absence of ... Read more Animals distinguish sugars from non-nutritive sweeteners even in the absence of sweet taste. This hidden sugar sense seems to reside in the gut, but the cells and neural circuits are unknown. In 2018, the Bohórquez Laboratory discovered a neural circuit linking the gut to the brain in one synapse. The neural circuit is formed between neuropod cells in the gut and the vagus nerve. This neural circuit is essential to convey sensory cues from sugars. In 2020, the Bohórquez Laboratory discovered using a new fiber optic technology along with optogenetics, that animals rely on neuropod cells to distinguish sugars from non-caloric sweeteners. Much like the brain relies on retinal cone cells to see color, gut neuropod cells help the brain’s choose sugar over non-caloric sweeteners.
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    Coupled Colloidal Quantum Dot Molecules

    Date:
    20
    Monday
    June
    2022
    Colloquium
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Uri Banin
    Organizer: Faculty of Chemistry
    Abstract: Colloidal semiconductor Quantum Dots (CQDs) containing hundreds to thousands of ... Read more Colloidal semiconductor Quantum Dots (CQDs) containing hundreds to thousands of atoms have reached an exquisite level of control, alongside gaining fundamental understanding of their size, composition and surface-controlled properties, leading to their technological applications in displays and in bioimaging. Inspired by molecular chemistry, deeming CQDs as artificial atom building blocks, how plentiful would be the selection of composition, properties and functionalities of the analogous artificial molecules? Herein we introduce the utilization of CQDs as basic elements in nanocrystal chemistry for construction of coupled colloidal nanocrystals molecules. Focusing on the simplest form of homodimer quantum dots (QDs), analogous to homonuclear diatomic molecules, we introduce a facile and powerful synthesis strategy with precise control over the composition and size of the barrier in between the artificial atoms to allow for tuning the electronic coupling characteristics and their optical properties. This sets the stage for nanocrystals chemistry to yield a diverse selection of coupled CQD molecules utilizing the rich collection of artificial atom core/shell CQD building blocks. Such CQD molecules are of relevance for numerous applications including in displays, photodetection, biological tagging, electric field sensing and quantum technologies.
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    Multiplexed imaging of endogenous molecular beacons with MRI

    Date:
    09
    Thursday
    June
    2022
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Moriel Vandsburger
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Abstract: Novel treatments that are under development for heart failure, metabolic disorde ... Read more Novel treatments that are under development for heart failure, metabolic disorders, kidney disease, and other debilitating illnesses generally target specific molecular and cellular mechanisms of action. However, assessment of such treatments is often complicated by the lack of easily measurable blood biomarkers, and a reliance upon repeated tissue biopsy. Subsequently, many exploratory studies utilize non-invasive imaging methods to characterize changes in whole organ structure and function as surrogate markers for underlying cellular and molecular changes. Although such measurements can be performed serially, such macro-level imaging measurements are often insensitive to physiologically meaningful treatment responses. In addition, the lack of target specificity represents a fundamental barrier both in pre-clinical development and clinical trials where the information potentially gleaned from a more physiologically rich data set would be of high value to further therapeutic development. My primary research interest is in using magnetic resonance imaging (MRI) as a platform technology for non-invasive and multiplexed molecular imaging in heart and kidney failure. Using a first principles approach, my group seeks to unify changes in myocardial and kidney MRI physics properties with advanced pulse sequence design and analysis in order to enable integrative physiological imaging that both identifies mechanisms of failure earlier than existing diagnostics, and directly measures the impacts of new therapies on their intended therapeutic targets. Using a process of chemical exchange saturation transfer (CEST) we have designed pre-clinical methods to quantify viral carriers of somatic cell gene editing machinery, gene transfer following adeno associated viral gene therapy, and to longitudinally quantify cell survival/proliferation following intra-myocardial implantation in mouse models of regenerative cell therapy. In addition, cardiac CEST approaches for imaging of myocardial creatine and fibrosis using endogenous contrast mechanisms have been translated from mouse models to clinical application in obese adults and renal failure patients on routine hemodialysis. Most recently we have developed methods to probe renal physiology and failure based on endogenous CEST contrast generated by urea. When integrated, these approaches can enable serially non-invasive and multi-scale analysis from the level of gene expression up to whole organ function in disease settings that currently have limited non-invasive molecular tools.
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    On discovery and sensitivity in (photo)catalysis

    Date:
    07
    Tuesday
    June
    2022
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Frank Glorius
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Catalysis is a key technology, since it allows for increased levels of selectivi ... Read more Catalysis is a key technology, since it allows for increased levels of selectivity and efficacy of chemical transformations. While significant progress can be made by rational design or engineered step-by-step improvements, many pressing challenges in the field require the discovery of new and formerly unexpected results. Arguably, the question “How to discover?” is at the heart of the scientific process. In this talk, (smart) screening strategies for accelerated discovery and improved reproducibility will be presented, together with new photocatalytic transformations. In addition, two other exciting areas will be addressed: N-heterocyclic carbenes (NHCs) are powerful ligands in catalysis due to their strong electron-donating properties and their ability to form very stable bonds to transition metals. In addition, they can stabilize and modify nanoparticles or flat metals surfaces, outperforming established phosphine or thiol ligands regarding structural flexibility, electron-donating properties and stability. Current research is highly interdisciplinary and focusses on the basic understanding of the binding mode, mobility and the elucidation of the impact on the surface properties. Exciting applications in materials science, heterogeneous catalysts and beyond are within reach. Biological membranes and their constituents are some of the most important and fundamental building blocks of life. However, their exact role in many essential cellular processes as well as in the development of diseases such as cancer or Alzheimer's is still not very well understood. Thus, we design, synthesize and evaluate imidazolium-based lipid analogs that can integrate into biological membranes and can be used as probes for live cell imaging or to manipulate membranes.
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    Fast multimodal imaging of brain dynamics underlying sleep and wakefulness

    Date:
    17
    Tuesday
    May
    2022
    Lecture / Seminar
    Time: 14:00-15:00
    Title: On ZOOM
    Lecturer: Dr. Laura Lewis
    Organizer: Department of Brain Sciences
    Details: ZOOM Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeH ... Read more ZOOM Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421
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    Abstract: When we fall asleep, brain function and physiology are rapidly transformed. Unde ... Read more When we fall asleep, brain function and physiology are rapidly transformed. Understanding the neural basis of sleep requires imaging methods that can capture multiple aspects of brain physiology at fast timescales. We develop approaches for analyzing human brain physiology using multimodal neuroimaging, and apply them to investigate the neural origins and consequences of sleep. We found that accelerated methods for fMRI can enable imaging subsecond neural dynamics throughout the human brain. We applied these methods to investigate the neural dynamics that occur at state transitions, and identified temporal sequences within thalamocortical networks that precede the moment of awakening from sleep. In addition, we developed a method to image cerebrospinal fluid flow, and discovered large waves of fluid flow that appear in the sleeping human brain. Together, these studies highlight the new biological information that can be extracted from fast fMRI data, and use this approach to discover neurophysiological dynamics unique to the sleeping brain. Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421
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    The awesome power of fluorine NMR - from drugs to cells

    Date:
    12
    Thursday
    May
    2022
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Prof. Angela M. Gronenborn
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Abstract: Nuclear magnetic resonance (NMR) spectroscopy is a versatile tool for probing st ... Read more Nuclear magnetic resonance (NMR) spectroscopy is a versatile tool for probing structure, dynamics, folding, and interactions at atomic resolution. While naturally occurring magnetically active isotopes, such as 1H, 13C, or 15N, are most commonly used in biomolecular NMR, with 15N and 13C isotopic labeling routinely employed at the present time, 19F is a very attractive and sensitive alternative nucleus, which offers rich information on biomolecules in solution and in the solid state. This presentation will summarize the unique benefits of solution and solid-state 19F NMR spectroscopy for the study of biomolecular systems. Particular focus will be placed on the most recent studies and on unique and important potential applications of fluorine NMR methodology.
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    Ambient Imaging of Biological Samples Using Nanospray Desorption Electrospray Ionization (nano-DESI) Mass Spectrometry

    Date:
    10
    Tuesday
    May
    2022
    Lecture / Seminar
    Time: 12:30
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Prof. Julia Laskin
    Organizer: Department of Life Sciences Core Facilities

    Probing Biomolecular Dynamics with Single-Molecule Spectroscopy

    Date:
    02
    Monday
    May
    2022
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Hagen Hofmann
    Organizer: Faculty of Chemistry
    Abstract: Explaining organisms in terms of the jiggling and wiggling of atoms is a central ... Read more Explaining organisms in terms of the jiggling and wiggling of atoms is a central goal in molecular biology. Yet, the dynamics of proteins with their sophisticated three-dimensional architectures exceeds the capabilities of
analytical theories. On the other
hand, intrinsically
disordered proteins are often well described by polymer theories of different flavors. However, these theories do not apply to proteins in which disorder and order mix. Combining structural biology with polymer theory is therefore required to understand such biomolecules. I will discuss how optical single-molecule spectroscopy allows us to probe the dynamics of (partially) disordered proteins and complexes from nanoseconds to milliseconds. I will show how many weak protein-protein interactions can cause rugged energy landscapes that slow-down dynamics by orders of magnitude. In the second part, I will discuss how we envision to bridge scales between molecules and cells at the example of a cellular phenotype switch that requires a dynamic interplay between proteins and DNA. While single-molecule tools to probe the kinetics of biomolecules are well developed, similar approaches to study the dynamics of cellular processes such as gene expression are scarce. In the final part of my talk I will therefore present a new approach to tackle this problem using single-particle tracking
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    Magnetic Resonance “Colors”: Design and Implementation in Materials and Life Sciences

    Date:
    25
    Monday
    April
    2022
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Amnon Bar-Shir
    Organizer: Faculty of Chemistry
    Abstract: Luminescent materials with their rich color palettes have revolutionized both sc ... Read more Luminescent materials with their rich color palettes have revolutionized both science and technology through the ability to distinguish between spectrally resolved colors for a wide range of applications from sensing to molecular steganography through high-end electronics and biomedical imaging. Yet, light-based colors suffer from limitations, such as strong scattering and absorbance in opaque media, restricted spectral resolution, photo-bleaching, intolerance for color-palette extendibility and more. Amongst the diverse capabilities and many advantages of Nuclear Magnetic Resonance (spectroscopy and imaging) several are unique, e.g., the sensitivity of the chemical shifts to the chemical environment, the penetrateability of MR signals across opaque objects and the ability to produce three dimensional images of studied subjects. Here, I discuss our recent developments of molecular probes that are capable to generate artificial MR-based colors. To this end, we use synthetic chemistry, nanofabrication, and protein engineering approaches to generate novel molecular formulations (small molecules, nanocrystals (NCs), supramolecular assemblies and proteins) as MRI sensors with unique, advantageous properties (sensitivity, specificity, orthogonality, etc.). I will also discuss how the very same molecular probes can be used to better understand fundamental scientific questions in supramolecular chemistry (e.g., kinetic features of dynamically exchanging molecular systems) and materials science (e.g., understanding and controlling NCs’ formation pathways).
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    Vision and AI

    Date:
    07
    Thursday
    April
    2022
    Lecture / Seminar
    Time: 12:15-13:15
    Title: Developing new strategies for high resolution imaging at ultra-high field human MRI
    Location: Jacob Ziskind Building
    Lecturer: Rita Schmidt
    Organizer: Faculty of Mathematics and Computer Science
    Abstract: Today, ultra-high-field MRI is at the forefront of the development for high-prec ... Read more Today, ultra-high-field MRI is at the forefront of the development for high-precision non-invasive imaging, capable of distinguishing between brain layers. In our lab, we utilize ultra-high field MRI to develop methods to increase the spatial and temporal resolution in scans that capture the structure and function of the human brain. We explore methods that can control the signal we collect, optimizing MRI signal encoding, scan acceleration and strategies of the signal acquisition, followed by computational approaches to improve the final image. I will show three examples. One is developing methods to increase temporal resolution in functional MRI, exploring strategies to capture the delay between neural processes. Another is developing quantitative method to characterize neurovascular and physiological changes in the human brain. With this technique, we are interested to follow the changes in the brain with age, gender and population, thus providing new insights for basic neuroscience and long-term personalized medicine. The last example shows how we can minimize a major sensitivity that is common to 3D whole brain acquisition – sensitivity to fluid movement during the scan duration, which results in severe artifacts in the images. This includes fluid in the ventricles that beats with cardiac pulsation, fluid movement in the eyes while moving our gaze and the blood flow in small vessels.
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    Complex biogenic crystals made by unicellular algae are constructed with simple principles

    Date:
    29
    Tuesday
    March
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Member Seminar
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Emanuel Avrahami
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Dr. Assaf Gal
    Abstract: Coccoliths are exoskeletal plates, made of highly complex microscopic calcite (C ... Read more Coccoliths are exoskeletal plates, made of highly complex microscopic calcite (CaCO3) crystals with astonishing morphological variety, produced by unicellular algae called Coccolithophores. For decades, their complexity has made coccolith fabrication and its controls alluring to scientists from different fields. Coccoliths grow intracellularly in a specialized vesicle where they presumably interact with chiral additives in a stereospecific manner. Such specific interactions are thought to give rise to numerous crystallographic faces, that convey ultrastructural chirality and convolutedness. We investigated the large coccoliths of Calcidiscus leptoporus by extracting them from within the cells along their growth, imagining them with various electron microscopy techniques at high resolution, and rendering their 3D structure. Our morphological analysis revealed that as the crystals mature, they transition from isotropic rhombohedra to highly anisotropic shapes, while expressing only a single set of crystallographic faces. This observation profoundly challenges the involvement of chiral modifiers. The crystals’ growth pattern showed that their shape is attained via differential growth rates of symmetry related facets with. Additionally, the rhombohedral geometry of the crystals appears to convey ultrastructural chirality in initial coccolith assembly stages. These findings change our understanding of biological control over complex crystal construction and mechanistically simplify the system in which they emerge.
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    Four disruptive technologies that are revolutionizing sensing of the oceans

    Date:
    20
    Sunday
    March
    2022
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Emmanuel Boss
    Organizer: Department of Earth and Planetary Sciences
    Abstract: The maker movement (cheap electronics + sharing), automated microscopy, autonom ... Read more The maker movement (cheap electronics + sharing), automated microscopy, autonomous platforms and small footprint satellites have been revolutionizing oceanography, opening a variety of new avenues for research and requiring a different education model. In this talk I will summarize a few activities my lab has been involved in that are associated with these disruptive technologies and why I am very optimistic for the future of our field in the coming years.
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    Diverse mechanisms of adaptive flexibility discovered by multi-species analysis of stomatal development

    Date:
    24
    Thursday
    February
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Location: https://weizmann.zoom.us/j/98989152393?pwd=a050Mm4rSlEwb2hLN1FiKy9oT24xdz09 Password: 002663
    Lecturer: Dr. Ido Nir
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Asaph Aharoni
    Abstract: An essential trait of plants is the ability to change intrinsic programs to alig ... Read more An essential trait of plants is the ability to change intrinsic programs to align with external signals. Plants can sense their environment and respond by refining their development program. A good example of sensing and response is the behavior of stomata. Plant stomata optimize the assimilation of carbon dioxide (CO2) for use in photosynthesis while minimizing water loss. They do this in two ways: by physiological control of when they are open or closed and by developmental regulation of their abundance and pattern. Both modes of control can be regulated by the environment, and as we face future climate change, with an increase in average global temperatures and water limitation, the understanding of how plants optimize stomatal production and patterns with the environment has fundamental importance. Our fullest understanding of the genetic control of stomatal development is from work in Arabidopsis. Here, development involves a core set of transcription factors whose expression and activity are regulated by signals from neighbor cells, from distant parts of the plant and from environmental cues like light, temperature, osmotic stress, and CO2 levels. But while Arabidopsis is a powerful model for stomatal development, this research showed that tomatoes often lean on different cellular and genetic strategies to achieve optimal stomatal distributions. Using novel genetically encoded reporters and custom microscopy for developmental time-course analysis, we found that, like in Arabidopsis, tomato undergoes a series of asymmetric and symmetric cell divisions to produce stomata. However, we found that not all asymmetric divisions (ACDs) are the same; certain classes of ACDs are missing in the tomato epidermis, and instead other types of ACDs are used to generate non-stomatal cells. ACDs have been shown in both plant and animal systems to enable tunable development. This findings in tomato indicate that there are new types of ACDs that could mediate species-specific control of cell production and tissue organization.
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    Intravital microscopy of the protection mechanisms that clear mutations in intestinal and breast tissues

    Date:
    17
    Thursday
    February
    2022
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Jacco van Rheenen
    Organizer: Dwek Institute for Cancer Therapy Research
    Details: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09

    Distributed views across media: From space to ocean-depths

    Date:
    13
    Sunday
    February
    2022
    Lecture / Seminar
    Time: 11:00
    Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09
    Lecturer: Yoav Schechner
    Organizer: Department of Earth and Planetary Sciences
    Abstract: By economy of scale, imaging sensors can now be deployed densely and operated in ... Read more By economy of scale, imaging sensors can now be deployed densely and operated in a coordinated manner at large numbers in space, air, underwater and on the ground. Such distributed imaging systems enable multi-view setups across heterogeneous media of importance to geoscience. These create new observation modes. One outcome is 4D volumetric spatiotemporal recovery of scatterers in the atmosphere, specifically cloud content (the core of the CloudCT space mission). This is in addition to computed tomography of underwater sediment suspension and atmospheric turbulence distributions. We describe several such systems - demonstrated in the field, including both distributed imaging and the basis of the algorithms to analyze the data.
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    Effects of physical exercise and adult neurogenesis on hippocampal neural codes

    Date:
    10
    Thursday
    February
    2022
    Lecture / Seminar
    Time: 09:00-10:00
    Lecturer: Yoav Rechavi - PhD Thesis Defense on Zoom
    Organizer: Department of Brain Sciences
    Details: Zoom link-https://weizmann.zoom.us/j/93585241611?pwd=RGsxakU2aElVQ01nbUpuRjVqOWQ ... Read more Zoom link-https://weizmann.zoom.us/j/93585241611?pwd=RGsxakU2aElVQ01nbUpuRjVqOWQ0QT09 Meeting ID: 935 8524 1611 Password: 243908
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    Abstract: ABSTRACT Physical activity plays a vital role in maintaining a healthy brain, au ... Read more ABSTRACT Physical activity plays a vital role in maintaining a healthy brain, augmenting memory and cognition in both humans and animals. Previous studies have identified multiple distinct molecular and cellular factors that mediate these effects, both within the brain and systemically. However, what remains unknown is how exercise affects the neural coding mechanisms that underlie these cognitive and memory abilities. In my work I addressed this question in the context of spatial cognition, and studied how chronic voluntary exercise affects the quality and the long-term stability of hippocampal place codes. I performed longitudinal imaging of calcium activity in the hippocampal CA1 of mice as they repeatedly explored initially novel environments over weeks, and compared the place codes of mice that voluntarily ran on wheels in their home cage to those of sedentary mice. As previously reported, physical activity enhanced adult neurogenesis rates in the hippocampal dentate gyrus in the running group. I found that running increased the firing rates and the information content that place cells carry about position. In addition, I discovered a surprising relationship between physical activity and long-term neural-code stability: although running mice demonstrated an overall more stable place code than sedentary mice, their place code exhibited a higher degree of representational drift when controlling for code quality level. Using a simulated neural network, I found that the combination of both improved code quality and faster representational drift in runners, but neither of these effects alone, could recapitulate my experimental results. Overall, these results imply a role for physical activity in both improving the spatial code and accelerating representational drift in the hippocampus. Zoom link-https://weizmann.zoom.us/j/93585241611?pwd=RGsxakU2aElVQ01nbUpuRjVqOWQ0QT09 Meeting ID: 935 8524 1611 Password: 243908
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    Dissecting temperature sensing and epigenetic switching using mathematical modelling and experiments

    Date:
    08
    Tuesday
    February
    2022
    Lecture / Seminar
    Time: 11:30
    Title: PES Dept. Special Guest Seminar
    Location: Zoom link:https://weizmann.zoom.us/j/97166592605?pwd=NVdrc1k4TDJBSXppTFY1Y0ViVzUxZz09 Meeting ID: 971 6659 2605 Password:782843
    Lecturer: Prof. Martin Howard
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Dr.David Zeevi
    Abstract: We are studying the mechanistic basis of epigenetic regulation in the Polycomb s ... Read more We are studying the mechanistic basis of epigenetic regulation in the Polycomb system, a vital epigenetic silencing pathway that is widely conserved from flies to plants to humans. We use the process of vernalization in plants in our experiments, which involves memory of winter cold to permit flowering only when winter has passed via quantitative epigenetic silencing of the floral repressor FLC. Utilising this system has numerous advantages, including slow dynamics and the ability to read out mitotic heritability of expression states through clonal cell files in the roots. Using mathematical modelling and experiments (including ChIP and fluorescent reporter imaging), we have shown that FLC cold-induced silencing is essentially an all-or-nothing (bistable) digital process. The quantitative nature of vernalization is generated by digital chromatin-mediated FLC silencing in a subpopulation of cells whose number increases with the duration of cold. We have further shown that Polycomb-based epigenetic memory is indeed stored locally in the chromatin (in cis) via a dual fluorescent labelling approach. I will also discuss how further predictions from the modelling, including opposing chromatin modification states and extra protein memory storage elements, are being investigated. I will also discuss the mechanisms by which long term fluctuating temperature signals are sensed before being converted into digital chromatin states for long term memory storage.
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    Zoom: M.Sc thesis defense: "Investigation of the ceramic – polymer interface in composite solid electrolyte by Nuclear Magnetic Resonance Spectroscopy"

    Date:
    30
    Sunday
    January
    2022
    Lecture / Seminar
    Time: 13:00-14:00
    Lecturer: Chen Oppenheim
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: https://weizmann.zoom.us/j/97328767376?pwd=MkZoQ0hmbVVRank0bzkxbGpqSUdYUT09 pas ... Read more https://weizmann.zoom.us/j/97328767376?pwd=MkZoQ0hmbVVRank0bzkxbGpqSUdYUT09 passcode: 891716 Lithium-ion batteries with liquid electrolytes are commonly employed for powering portable electronic devices. To expand the range of applications where Li ions batteries can be used (e.g., electric transportation), solid electrolytes are considered as a safer alternative to the liquid electrolytes and they may enable use of lithium metal anodes. In this study we focused on composite solid electrolytes which are based on solid polymer (Polyethylene Oxide) and ceramic particles (Li1.5Al0.5Ge1.5P3O12, LAGP). Previous studies revealed that the highest ionic conduction path in the composites is through the interface polymer - ceramic interface. However, the chemical nature of the interface and the reason for its higher conductivity remains unclear. We aim to gain molecular - atomic level insight into the nature of the polymer - ceramic interface from solid state NMR spectroscopy. Here, I will present the development of a solid - state NMR approach that can potentially be used to selectively probe the interface. To gain sensitivity and selectivity Dynamic Nuclear Polarization (DNP), a process in which high polarization from unpaired electrons is transferred to surrounding nuclear spins will be employed. Several metal ion dopants were tested for their DNP performance in LAGP powder, and Mn2+ ions were further examined in their efficacy in the composite electrolyte. The approach was tested for selectively enhancing the NMR signal of the PEO - LAGP interface. Electrochemical characterization and in - depth solid state NMR studies provided insight into the performance of the composite and degradation processes in the composite.
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    M.Sc thesis defense: Characterization of anisotropic strain in anelstic materials by Raman spectroscopy

    Date:
    26
    Wednesday
    January
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Lecturer: Daniel Freidson
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Link: https://weizmann.zoom.us/j/96430042316?pwd=cjJwdFUrSEE5VnU4eVNuY08 ... Read more Zoom Link: https://weizmann.zoom.us/j/96430042316?pwd=cjJwdFUrSEE5VnU4eVNuY08wZ1F3QT09 Raman spectroscopy is used as a primary non-destructive tool for characterization of strain in thin films. It is based on the concept of the mode Grüneisen parameter, which is the ratio between the relative change in the energy of a given vibrational mode and the relative change in the unit cell volume. It has been recently reported (Kraynis et al.) that under biaxial strain, doped CeO2-films exhibit values of the mode Grüneisen parameter, which are up to 40% smaller than the bulk literature value. Doped CeO2-films are strongly anelastic, posing a question on the relation between Raman scattering frequency and anelastic strain. This work describes the way to separate anelastic and elastic contributions to the Grüneisen parameter of doped ceria thin films and show that this concept remains applicable, if only the elastic part of the strain must be taken into account. As a reference, I deposited a purely elastic yittria thin film by sputter deposition and calculated its Grüneisen parameter in a similar way. The experimental and literature values of the yittria Grüneisen parameter were found compatible, confirming that for purely elastic strain, Grüneisen parameter concept is fully applicable.
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    Direct Imaging of Planet Formation

    Date:
    16
    Sunday
    January
    2022
    Lecture / Seminar
    Time: 11:00-12:00
    Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09
    Lecturer: Sivan Ginzburg
    Organizer: Department of Earth and Planetary Sciences
    Abstract: The vast majority of detected planets are observed indirectly, using their small ... Read more The vast majority of detected planets are observed indirectly, using their small perturbation on the light emitted by the host stars. In recent years, however, the world's largest ground based telescopes have succeeded in directly imaging the light coming from some planets themselves. I will present our comprehensive theory for the mass, luminosity, and spin of gas giant planets during their final stages of formation - when they simultaneously contract and accrete gas from a disk. I will apply this theory to the luminosity and spectrum obtained by the novel direct-imaging technique, highlighting the recently discovered PDS 70 system, where two planets were directly observed during formation for the first time.
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    Investigating the mechanisms underlying the stable coexistence of multiple maps for the same environment

    Date:
    05
    Wednesday
    January
    2022
    Lecture / Seminar
    Time: 10:00-11:00
    Title: Student Seminar - MSc Thesis Defense - ZOOM -
    Lecturer: Alice Eldar- MSc Thesis Defense
    Organizer: Department of Brain Sciences
    Details: Zoom: https://weizmann.zoom.us/j/92871200575?pwd=WWdZbXVmM1R5RkFZYnpTajloelVTZz0 ... Read more Zoom: https://weizmann.zoom.us/j/92871200575?pwd=WWdZbXVmM1R5RkFZYnpTajloelVTZz09 Meeting ID: 928 7120 0575 Password: 344121
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    Abstract: Hippocampal place cells fire at a high rate whenever an animal is in a specific ... Read more Hippocampal place cells fire at a high rate whenever an animal is in a specific location in an environment and are thought to support spatial and episodic memory. When an animal visits different environments, place cells typically ‘remap’ (i.e., change their preferred locations), and when revisiting the same environment, the same spatial code reemerges. In a recent study by our lab, place cells were shown to globally remap, forming multiple distinct representations (maps) of the same environment that stably coexist across time. In that study, switching between different maps of the same environment happened only after the mice were disconnected from the environment.             Here I performed a set of experiments to further understand the mechanism underlying switching between multiple maps. My project established a way to manipulate this mechanism, both through external orientation inputs and by acting directly on the hippocampal network state using optogenetics. My results provide support for the proposed role of head-direction or other orientation signals in the switching between maps. They also support the model of maps as stable attractors, where the specific attractor (map) used depends on the initial conditions of the network. Zoom: https://weizmann.zoom.us/j/92871200575?pwd=WWdZbXVmM1R5RkFZYnpTajloelVTZz09 Meeting ID: 928 7120 0575 Password: 344121
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    Zoom Seminar-Neuroimaging in drug addiction: an eye towards intervention development

    Date:
    30
    Thursday
    December
    2021
    Lecture / Seminar
    Time: 14:00-15:00
    Lecturer: Prof. Rita Goldstein
    Organizer: Department of Brain Sciences
    Details: Zoom Lindk-https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeH ... Read more Zoom Lindk-https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID 954 0689 3197 Password 750421 Host-Dr. Michal Ramot, michal.ramot@weizmann.ac.il tel 4417
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    Abstract: : Drug addiction is a chronically relapsing disorder characterized by compulsive ... Read more : Drug addiction is a chronically relapsing disorder characterized by compulsive drug use despite catastrophic personal consequences (e.g., loss of family, job) and even when the substance is no longer perceived as pleasurable. In this talk, I will present results of human neuroimaging studies, utilizing a multimodal approach (neuropsychology, functional magnetic resonance imaging, event-related potentials recordings), to explore the neurobiology underlying the core psychological impairments in drug addiction (impulsivity, drive/motivation, insight/awareness) as associated with its clinical symptomatology (intoxication, craving, bingeing, withdrawal). The focus of this talk is on understanding the role of the dopaminergic mesocorticolimbic circuit, and especially the prefrontal cortex, in higher-order executive dysfunction (e.g., disadvantageous decision-making such as trading a car for a couple of cocaine hits) in drug addicted individuals. The theoretical model that guides the presented research is called iRISA (Impaired Response Inhibition and Salience Attribution), postulating that abnormalities in the orbitofrontal cortex and anterior cingulate cortex (and other prefrontal cortical regions underlying higher order executive function), as related to dopaminergic dysfunction, contribute to the core clinical symptoms in drug addiction. Specifically, our multi-modality program of research is guided by the underlying working hypothesis that drug addicted individuals disproportionately attribute reward value to their drug of choice at the expense of other potentially but no-longer-rewarding stimuli, with a concomitant decrease in the ability to inhibit maladaptive drug use. In this talk I will also explore whether treatment (as usual) and 6-month abstinence enhance recovery in these brain-behavior compromises in treatment seeking cocaine addicted individuals. Promising neuroimaging studies, which combine pharmacological (i.e., oral methylphenidate, or RitalinTM) and salient cognitive tasks or functional connectivity during resting-state, will be discussed as examples of using neuroimaging in the empirical guidance for the development of effective neurorehabilitation strategies (including cognitive reappraisal, mindfulness, and transcranial direct current stimulation) in drug addiction. Zoom Lindk-https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID 954 0689 3197 Password 750421
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    Vision and AI

    Date:
    23
    Thursday
    December
    2021
    Lecture / Seminar
    Time: 15:00-16:00
    Title: Computational Imaging for Sensing High-speed Phenomena
    Lecturer: Mark Sheinin
    Organizer: Faculty of Mathematics and Computer Science
    Abstract: Despite recent advances in sensor technology, capturing high-speed video at high ... Read more Despite recent advances in sensor technology, capturing high-speed video at high-spatial resolutions remains a challenge. This is because, in a conventional camera, the available bandwidth limits either the maximum sampling frequency or the captured spatial resolution. In this talk, I am going to cover our recent works that use computational imaging to allow high-speed high-resolution imaging under certain conditions. First I will describe Diffraction Line Imaging, a novel imaging principle that combines diffractive optics with 1D (line) sensors to allow high-speed positioning of light sources (e.g., motion capture markers, car headlights) as well structured light 3D scanning with line illumination and line sensing. Second, I will present a recent work that generalizes Diffraction Line Imaging to handle a new class of scenes, resulting in new application domains such as high-speed imaging for Particle Image Velocimetry and imaging combustible particles. Lastly, I will present a novel method for sensing vibrations at high speeds (up to 63kHz), for multiple scene sources at once, using sensors rated for only 130Hz operation. I will present results from our method that include capturing vibration caused by audio sources(e.g. speakers, human voice, and musical instruments) and analyzing the vibration modes of a tuning fork.
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    Student Seminar

    Date:
    21
    Tuesday
    December
    2021
    Lecture / Seminar
    Time: 11:00-12:00
    Title: A spatiotemporally resolved single cell atlas of the Plasmodium liver stage
    Location: Wolfson Building for Biological Research
    Lecturer: Amichay Afriat
    Organizer: Department of Molecular Cell Biology
    Abstract: Malaria infection involves an obligatory, yet clinically silent liver stage. Hep ... Read more Malaria infection involves an obligatory, yet clinically silent liver stage. Hepatocytes operate in repeating units termed lobules, exhibiting heterogeneous gene expression patterns along the lobule axis, but the effects of hepatocyte zonation on parasite development have not been molecularly explored. In our work, we combine single-cell RNA sequencing and single-molecule transcript imaging to characterize the host’s and parasite’s temporal expression programs in a zonally-controlled manner for the rodent malaria parasite Plasmodium berghei ANKA. We identify differences in parasite gene expression in distinct zones, and a sub-population of periportally-biased hepatocytes that harbor abortive infections associated with parasitophorous vacuole breakdown. These ‘abortive hepatocytes’ up-regulate immune recruitment and key signaling programs. They exhibit reduced levels of Plasmodium transcripts, perturbed parasite mRNA localization, and may give rise to progressively lower abundance of periportal infections. Our study provides a resource for understanding the liver stage of Plasmodium infection at high spatial resolution and highlights heterogeneous behavior of both the parasite and the host hepatocyte.
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    Vision and AI

    Date:
    16
    Thursday
    December
    2021
    Lecture / Seminar
    Time: 12:15-13:15
    Title: Learning to see in the Data Age
    Lecturer: Alex Bronstein
    Organizer: Faculty of Mathematics and Computer Science
    Abstract: Recent spectacular advances in machine learning techniques allow solving complex ... Read more Recent spectacular advances in machine learning techniques allow solving complex computer vision tasks -- all the way down to vision-based decision making. However, the input image itself is still produced by imaging systems that were built to produce human-intelligible pictures that are not necessarily optimal for the end task. In this talk, I will try to entertain ourselves with the idea of including the camera hardware (optics and electronics) among the learnable degrees of freedom. I will show examples from optical, ultrasound, and magnetic resonance imaging demonstrating that simultaneously learning the "software" and the "hardware" parts of an imaging system is beneficial for the end task.
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    AMOS Seminar

    Date:
    16
    Tuesday
    November
    2021
    Lecture / Seminar
    Time: 13:15-14:15
    Title: From Hanbury-Brown and Twiss to photon correlation enhanced spectroscopy and microscopy
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Dan Oron
    Organizer: Department of Physics of Complex Systems
    Abstract: When Hanbury-Brown and Twiss proposed to use photon correlations for stellar int ... Read more When Hanbury-Brown and Twiss proposed to use photon correlations for stellar interferometry in 1954 the idea was received with great skepticism. Yet, the use of photon correlations for various uses, from identification of quantum emitters to emitter counting grew over the years. In the talk, I will describe some of our efforts in using HBT correlations and their derivatives in superresolution microscopy and in advanced spectroscopy of quantum emitters, as well as the technological advances enabling this.
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    Systematic Discovery and Characterization of Microbial Toxins

    Date:
    16
    Tuesday
    November
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Guest seminar
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Asaf Levy
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: David Zeevi
    Abstract: Microbes use protein toxins to kill competitors and to infect host cells. Discov ... Read more Microbes use protein toxins to kill competitors and to infect host cells. Discovering new toxins and describing their function is important to understand processes in microbial ecology and host-microbe interactions. Moreover, the toxins can be used in various applications, including drugs, pesticides, vaccines, potent enzymes, etc. We study toxins in the lab by combining large-scale computational genomics and molecular microbiology. In the talk, I will tell two recent stories from the lab on microbial toxins and their secretion systems. The first study is about the mysterious extracellular contractile injection system. This toxin delivery system evolved from a phage into a molecular weapon employed by bacteria against eukaryotic cells. In the second study, I will tell about the exciting group of polymorphic toxins. These are large toxin proteins that undergo recombination to create large diversity of antimicrobial toxins. We developed methods to discover toxins from both groups, study the ecological role of the toxins, and their molecular function. These approaches led to discovery of over 30 novel microbial toxins that we study in the lab.
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    “Displacement spectrum imaging of flow and tissue perfusion”

    Date:
    11
    Thursday
    November
    2021
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. S. Michael (Miki) Lustig
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Abstract: Hybrid @ Schmidt Lecture Hall Zoom : Zoom Link: https://weizmann.zoom.us/j/98 ... Read more Hybrid @ Schmidt Lecture Hall Zoom : Zoom Link: https://weizmann.zoom.us/j/98811093126?pwd=RVVDK3RieStHY3R6T0xMZndZeGIwZz09 We propose a new method, displacement spectrum (DiSpect) imaging, for probing in vivo complex tissue dynamics such as motion, flow, diffusion, and perfusion. Based on stimulated echoes and image phase, our flexible approach enables observations of the spin dynamics over short (milliseconds) to long (seconds) evolution times.
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    Ph.D thesis defense: “Structural and optoelectronic properties of surface-guided halide perovskite nanowires”

    Date:
    10
    Wednesday
    November
    2021
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Ella Sanders
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Metal halide perovskites (MHPs) have re-emerged as exceptional semiconductor mat ... Read more Metal halide perovskites (MHPs) have re-emerged as exceptional semiconductor materials for photovoltaics and optoelectronics, gaining tremendous attention in the fields of materials and energy harvesting over the past decade. Their unique properties, alongside their relatively cheap and easy production, make them excellent candidates as materials for the next-generation optoelectronic technologies. Besides their technological advantage, their soft ionic lattice and anharmonic potential, that are part of the underlying reasons for their unusual and outstanding performance, challenge the well-established models of classical semiconductor physics and provoke many scientific research opportunities and questions. In order to intrinsically study these outstanding behaviors, a simple system is requires, diminishing complexities that can arise when examining the popularly studied polycrystalline thin films that contain multiple defects, mainly grain boundaries. Over the past decade, our group has been developing and mastering the surface-guided growth of horizontal semiconductor NWs, which can be employed to grow arrays of epitaxial single crystal MHP NWs. These NWs offer a unique opportunity as a simple model-system for investigating the intrinsic properties of MHPs, due to their single crystal nature and quasi one-dimensional structure. These are especially suitable for the investigation of how lattice strain affects the materials’ properties, considering their inherent heteroepitaxial strain. The aim of this PhD work was to gain insight on the growth of surface-guided CsPbBr3 NWs, as a representative of the MHP family, and study the effect of epitaxial strain on their structure and properties. To achieve this goal, we first developed the crystal growth of the surface-guided CsPbBr3 NWs on sapphire, by a few different vapor-phase methods. We inspected their growth in situ using simple optical microscopy to try to learn how these unique materials grow. These were followed by integration of the NWs into nanodevices in order to examine their optoelectronic properties, with a special emphasis on the influence of strain on their performance. We finally exemplified a high-throughput study using an automated optical system that can probe many NWs in a short amount of time, to develop a charge-carrier behavior model based on a large amount of data. Studying the epitaxially strained surface-guided CsPbBr3 NWs provides important insight into the crystal growth and optoelectronic properties of MHPs
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    Brain-wide networks underlying behavior - Insights from functional ultrasound imaging

    Date:
    02
    Tuesday
    November
    2021
    Lecture / Seminar
    Time: 12:30-13:30
    Lecturer: Dr. Emilie Macé
    Organizer: Department of Brain Sciences
    Details: Zoom link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeH ... Read more Zoom link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421 Host: Dr. Takashi Kawashima takashi.kawashima@weizmann.ac.il tel: 2995
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    Abstract: Functional ultrasound imaging (fUS) is an emerging neuroimaging tool capable of ... Read more Functional ultrasound imaging (fUS) is an emerging neuroimaging tool capable of measuring brain-wide vascular signals linked to neuronal activity with a high spatial-temporal resolution (100 µm, 10 Hz) in real-time. This technology is portable, affordable and adaptable to many species, and has already found applications in areas ranging from basic research to the clinic. Focusing on fundamental neuroscience, I will outline some of the recent technical advancements of fUS, such as the capacity to image the entire rodent brain while manipulating specific neuronal circuits with optogenetics. I will exemplify how promising this imaging technique is for shedding new light on the brain-wide circuits underlying behavior, as fUS is one of the few methods that enables imaging of activity deep in the brain of behaving mice. Zoom link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09 Meeting ID: 954 0689 3197 Password: 750421
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    Zoom: “Fast, accessible hyperpolarization for MRI and liquid-state NMR”

    Date:
    28
    Thursday
    October
    2021
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Ilai Schwartz
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Details: .
    Abstract: Zoom Lecture: Zoom: : https://weizmann.zoom.us/j/92362836861?pwd=Q29EMVcxaXJ ... Read more Zoom Lecture: Zoom: : https://weizmann.zoom.us/j/92362836861?pwd=Q29EMVcxaXJkSE5QbWxpUEdPdGNQUT09 Passcode: 526083 Nuclear spin hyperpolarization provides a promising route to overcome the challenges imposed by the limited sensitivity of nuclear magnetic resonance. Significant progress in the last decades was achieved by the development of new hyperpolarization techniques (e.g. dissolution-DNP). This has resulted in the demonstration of new MRI applications utilizing hyperpolarized 13C nuclei in metabolic probes as well as promising results in hyperpolarized liquid state NMR. However, hyperpolarization for both MRI and liquid state NMR applications is still a challenging endeavor, requiring expensive hardware and imposing limitations on the experimental setup. In this talk I will present our latest developments for achieving fast, accessible polarization for both MRI and NMR applications utilizing a variety of polarization techniques: (1) For MRI applications we have demonstrated for the first time that using parahydrogen induced polarization (PHIP), hyperpolarized fumarate and pyruvate can be prepared at clinically relevant concentrations (> 100mM) and hyperpolarization values up to 20% at the time of injection. In a comparative study we show that PHIP based methods can compete and even surpass both polarization and concentration levels of metabolic tracers prepared by DNP but at a fraction of the cost, complexity and preparation time. (2) Leveraging optical polarization, we developed a technique for versatile liquid state NMR hyperpolarization, achieving between 200- and 1730-fold signal enhancement at 1.45T for a range of small molecules. The signal enhancement is induced by using optically polarized pentacene-doped naphthalene crystals as a source of spin polarization. We demonstrate that rapid dissolution of the highly polarized crystal enables transfer of polarization to the target molecules via intermolecular cross relaxation in the liquid state at room temperature. Due to the extremely high magnetization of the naphthalene molecules, the cross relaxation leads to a substantial polarization buildup in the target analytes. Crucially, the polarization transfer is achieved without costly instrumentation and occurs in less than a minute inside the NMR spectrometer
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    Unraveling the microscale mechanisms driving particle degradation in the ocean

    Date:
    26
    Tuesday
    October
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Location: https://weizmann.zoom.us/j/96896290817?pwd=WmoxNzZSRFArL3VzNUY3bHRpZFZoQT09 Password: 230371
    Lecturer: Dr. Uria Alcolombri
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Asaph Aharoni
    Abstract: The sinking of organic particles in the ocean and their degradation by marine mi ... Read more The sinking of organic particles in the ocean and their degradation by marine microorganisms drive one of the most conspicuous carbon fluxes on Earth, the biological pump. Yet, the mechanisms determining the magnitude of the pump remain poorly understood, limiting our ability to predict this carbon flux in future ocean scenarios. Current ocean models assume that the biological pump is governed by the competition between sinking speed and degradation rate, with the two processes independent from one another. In this talk, I will demonstrate that contrary to this paradigm, sinking itself is a primary determinant of the rate at which bacteria enzymatically degrade particles in the ocean. By combining video microscopy and microfluidic experiments to directly observe and quantify bacterial degradation of individual organic particles in flow, I will show that even modest sinking speeds of 8 meters per day enhance degradation rates more than 10-fold. I will further discuss the molecular mechanism behind the sinking-enhanced degradation, as well as possible ways by which bacteria can slow the sinking of particles. Finally, using the results obtained from a mathematical model, I will show that the coupling of sinking and degradation may contribute to determining the magnitude of the vertical carbon flux in the ocean, and will outline major open questions in the field.
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    Unraveling the microscale mechanisms driving particle degradation in the ocean

    Date:
    26
    Tuesday
    October
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Guest Seminar via zoom
    Location: https://weizmann.zoom.us/j/96896290817?pwd=WmoxNzZSRFArL3VzNUY3bHRpZFZoQT09 Password: 230371
    Lecturer: Dr. Uria Alcolombri
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Asaph Aharoni
    Abstract: The sinking of organic particles in the ocean and their degradation by marine mi ... Read more The sinking of organic particles in the ocean and their degradation by marine microorganisms drive one of the most conspicuous carbon fluxes on Earth, the biological pump. Yet, the mechanisms determining the magnitude of the pump remain poorly understood, limiting our ability to predict this carbon flux in future ocean scenarios. Current ocean models assume that the biological pump is governed by the competition between sinking speed and degradation rate, with the two processes independent from one another. In this talk, I will demonstrate that contrary to this paradigm, sinking itself is a primary determinant of the rate at which bacteria enzymatically degrade particles in the ocean. By combining video microscopy and microfluidic experiments to directly observe and quantify bacterial degradation of individual organic particles in flow, I will show that even modest sinking speeds of 8 meters per day enhance degradation rates more than 10-fold. I will further discuss the molecular mechanism behind the sinking-enhanced degradation, as well as possible ways by which bacteria can slow the sinking of particles. Finally, using the results obtained from a mathematical model, I will show that the coupling of sinking and degradation may contribute to determining the magnitude of the vertical carbon flux in the ocean, and will outline major open questions in the field.
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    Systematic analysis of contact site proteomes reveals novel players in cellular homeostasis Maya Schuldiner, Weizmann Institute of Science

    Date:
    26
    Tuesday
    October
    2021
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Maya Schuldiner
    Organizer: Department of Biomolecular Sciences
    Abstract: To communicate and work cooperatively, organelles must come into close proximity ... Read more To communicate and work cooperatively, organelles must come into close proximity at membrane contact sites to transfer lipids and small metabolites. Despite our increasing understanding of membrane contact sites, many of their molecular components have yet to be identified, making it difficult to investigate their over-arching roles in cellular and organism function. To overcome this limitation, we established a systematic and high throughput microscopy approach to identify contact site resident proteins in the budding yeast Saccharomyces cerevisiae. Using this method, we have identified multiple new contact site proteins. I will share an example of how mechanistic follow-up on such new contact residents is leading to a new understanding of organelle Biology.
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    Joint DPPA and AMOS Seminar

    Date:
    18
    Monday
    October
    2021
    Lecture / Seminar
    Time: 12:30
    Title: Precision measurements in exotic atoms
    Location: https://weizmann.zoom.us/j/93725660956?pwd=L1hOZXhkR0VLb0s4ckl0NzFqS09KUT09
    Lecturer: Ben Ohayon
    Organizer: Faculty of Physics
    Details: 12:10 Sandwiches and more...
    Abstract: Bound exotic systems offer unique opportunities to test our understanding of the ... Read more Bound exotic systems offer unique opportunities to test our understanding of the tenets of modern physics and determine fundamental constants. By comparing measured transitions between antihydrogen and hydrogen, we can search for CPT violation, which may explain the observed baryon asymmetry in the universe while respecting the stringent bounds on CP violation within the standard model. The comparison of the energy levels of muonium (M) with their clean theoretical prediction searches for new physics in a multitude of scenarios such as Lorentz and CPT violation in the muonic sector, and new bosons coupled to leptons. Such particles are motivated by the persistent discrepancy between the recently remeasured anomalous magnetic moment of the muon and its theoretical prediction, arguably the most promising hint to new physics in decades. In this talk I will review ongoing work for antihydrogen and M spectroscopy at CERN and PSI, and present our recent measurement of the Lamb-Shift in M, comprising an order of magnitude of improvement upon the state of the art and the first improvement to M energy levels in 20 years. I will conclude by showing that pushing M spectroscopy to its limits could independently determine the muon g-2 with enough accuracy to shed light on the puzzle.
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    Time and experience dependent evolution of hippocampal memory codes

    Date:
    11
    Monday
    October
    2021
    Lecture / Seminar
    Time: 13:30-14:30
    Lecturer: Nitzan Geva (PhD Defense)
    Organizer: Department of Brain Sciences
    Details: Zoom link to join: https://weizmann.zoom.us/j/98861083979?pwd=Q1FmbDBYNHR2QnN ... Read more Zoom link to join: https://weizmann.zoom.us/j/98861083979?pwd=Q1FmbDBYNHR2QnNKSUNpeHlLdm94dz09 Meeting ID: 988 6108 3979 Password: 682422
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    Abstract: Hippocampal place cells fire in a spatially selective manner and are thought to ... Read more Hippocampal place cells fire in a spatially selective manner and are thought to support the formation of a cognitive-map that allows the association of an event to its spatial context. It has long been thought that within familiar spatial contexts, such cognitive maps should be stable over time, and that individual place cells should retain their firing properties. However, recent findings have demonstrated that hippocampal spatial codes gradually change over timescales of minutes to weeks. These finding raised several fundamental questions: What are the contributions of the passage of the time and the amount of experience to the observed drift in hippocampal ensemble activity? To what extent are different aspect of place code stability affected by time and experience? To address these questions, I conducted a series of Ca2+ imaging experiments in which mice repeatedly explored familiar environments. Different environments were visited at different intervals, which allowed distinguishing between the contribution of time and experience to code stability. I found that time and experience differentially affected distinct aspects of hippocampal place codes: changes in activity rates were mostly affected by time, whereas changes in spatial tuning was mostly affected by experience. These findings suggest that different biological mechanisms underlie different aspects of representational drift in the hippocampus. These findings add to the growing body of research suggesting that representational drift is an inherent property of neural networks in vivo, and point to the different candidate mechanisms that could underlie this drift. https://weizmann.zoom.us/j/98861083979?pwd=Q1FmbDBYNHR2QnNKSUNpeHlLdm94dz09 Meeting ID: 988 6108 3979 Password: 682422
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    Special seminar with Dr. Yaara Oren

    Date:
    16
    Monday
    August
    2021
    Lecture / Seminar
    Time: 15:00-16:00
    Title: Beyond Darwin: understanding cancer persister cells
    Lecturer: Dr. Yaara Oren
    Organizer: Department of Molecular Genetics
    Details: zoom: https://weizmann.zoom.us/j/96160519106?pwd=ZSs0NXd0WWZSaTBQTTRxSkZ5dmRvdz09
    Abstract: Despite favorable initial response to therapy, a third of cancer patients will d ... Read more Despite favorable initial response to therapy, a third of cancer patients will develop recurrent disease and succumb to it within five years of diagnosis. While there has been much progress in characterizing the pathways that contribute to stable genetic drug resistance, the mechanisms underlying early reversible resistance, also known as persisters-driven resistance, remain largely unknown. It has long been believed that persisters represent a subset of cells that happen to be non-proliferating at the time of treatment, and therefore can survive drugs that preferentially kill rapidly proliferating cells. However, in my talk I will describe a rare persister population which, despite not harboring any resistance-conferring mutation, can maintain proliferative capacity in the presence of drug. To study this rare, transiently-resistant, cycling persister population, we developed Watermelon, a high-complexity expressed barcode lentiviral library for simultaneous tracing of each cell’s clonal origin and proliferative and transcriptional states. We combine single cell transcriptomics with imaging and metabolomics to show that cycling and non-cycling persisters arise from different cell lineages with distinct transcriptional and metabolic programs. Finally, I will describe how by studying persister cells we can gain critical insights on cellular memory, fate, and evolution, which can guide the development of better anti-cancer treatments.
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    Principles of functional circuit connectivity: Insights from the zebrafish optic tectum

    Date:
    04
    Wednesday
    August
    2021
    Lecture / Seminar
    Time: 10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. German Sumbre
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Takashi Kawashima takashi.kawashima@weizmann.ac.il tel: 2995
    Abstract: Spontaneous neuronal activity in sensory brain regions is spatiotemporally struc ... Read more Spontaneous neuronal activity in sensory brain regions is spatiotemporally structured, suggesting that this ongoing activity may have a functional role. Nevertheless, the neuronal interactions underlying these spontaneous activity patterns, and their biological relevance, remain elusive. We addressed these questions using two-photon and light-sheet Ca2+ imaging of intact zebrafish larvae to monitor the fine structure of the spontaneous activity in the zebrafish optic tectum (the fish's main visual center. We observed that the spontaneous activity was organized in topographically compact assemblies, grouping functionally similar neurons rather than merely neighboring ones, reflecting the tectal retinotopic map. Assemblies represent all-or-none-like sub-networks shaped by competitive dynamics, mechanisms advantageous for visual detection in noisy natural environments. Furthermore, the spontaneous activity structure also emerged in “naive” tecta (tecta of enucleated larvae before the retina connected to the tectum). We thus suggest that the formation of the tectal network circuitry is genetically prone for its functional role. This capability is an advantageous developmental strategy for the prompt execution of vital behaviors, such as escaping predators or catching prey, without requiring prior visual experience. Mutant zebrafish larvae for the mecp2 gene display an abnormal spontaneous tectal activity, thus representing an ideal control to shed light on the biological relevance of the tectal functional connectivity. We found that the tectal assemblies limit the span of the visual responses, probably improving visual spatial resolution.
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    Love the neighbor – Unraveling the tumor microenvironment using multiplexed imaging

    Date:
    08
    Thursday
    July
    2021
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Max and Lillian Candiotty Building
    Lecturer: Dr. Leeat Keren
    Organizer: Dwek Institute for Cancer Therapy Research
    Details: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09

    Yes I Can ! Neural indicators of self-views and their motivational value

    Date:
    22
    Tuesday
    June
    2021
    Lecture / Seminar
    Time: 12:30
    Lecturer: Prof. Talma Hendler
    Organizer: Department of Brain Sciences
    Details: Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: Positive view of oneself is central for social motivation and emotional well-b ... Read more Positive view of oneself is central for social motivation and emotional well-being. Such views largely depend on the known positive-bias of social feedbacks, as well as on the value one gives to social attributes such as power or affiliation. Diminished positive self views are a common denominator in depression and social anxiety, suggesting a transdiagnostic biomarkers, yet its neural mechanism is unclear. My talk will describe a series of studies using multiscale imaging and behavioral accounts and their modeling to address the interaction between self related cognition, motivation and learning from experience. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    The interaction of valence and information gain during learning, perception and decision-making

    Date:
    27
    Thursday
    May
    2021
    Lecture / Seminar
    Time: 11:00-12:30
    Lecturer: Ido Toren (PhD Thesis Defense)
    Organizer: Department of Brain Sciences
    Details: Neurobiology Students & Postdocs Seminar Zoom link to join: https://weizmann. ... Read more Neurobiology Students & Postdocs Seminar Zoom link to join: https://weizmann.zoom.us/j/92234357805?pwd=aVkrR21CSUVtVS9tSEJYRDkwOFRidz09 Meeting ID: 922 3435 7805 Password: 648092
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    Abstract: Decision making is a fundamental ability to human life. Even the simplest decisi ... Read more Decision making is a fundamental ability to human life. Even the simplest decision we make requires integration of multiple factors in our brain, such as prior knowledge, information from the environment, emotions and many more. Despite many years of research and numerous important and ground-breaking findings on how learning and decision-making are generated in our brain, a lot of knowledge is still required for a comprehensive understanding of it. My research initiated from the motivation to understand the unique contribution of valence (rewards and punishments) – when presented as feedback during learning – to perception and decision-making. For that purpose, I studied multiple groups of individuals under different experimental conditions created to elucidate behavioral and neural responses to rewards and punishments. I asked how prediction errors (PE, the difference between expected and received outcomes) bias the perception of time, and how valence and information from feedback, factors that are often indistinguishable, differently guide decision making in a multi-choice environment. Using functional MRI and computational models, I found that positive and negative PEs, known to drive learning, bias the perception of time in opposite directions. Positive PEs induce change in the perceived time so it seems longer compared to a neutral condition (no PE). In contrast, when a negative PE is detected, time is perceived to be shorter. My results identify the Putamen, a structure that receives dopaminergic projections and is involved in time perception, as the brain region that likely drives this bias and underlies the interaction between time perception and prediction-errors. In addition, I demonstrated that knowing the outcome valence in advance can enable an information-based decision making, namely one that is not affected by the valence itself and is driven only by the information available in the environment. Because uncertainty regarding choice increases when more options are available to choose from, a ‘right’ feedback provides more information to the learning process, compared to a ‘wrong’ feedback. This was accompanied by a differential activation in the ACC, PFC and striatum. Importantly, in this context, punishment avoidance is equally rewarding, and indeed I found that choice behavior and the neural networks underlying choice and feedback processing are similar in the two scenarios – for punishments and rewards. Overall, my work develops and suggests computational and neural mechanisms for specific roles of the information carried by prediction-errors. These findings can enhance our understanding of the fundamental roles of valence and information gain during learning and decision making. Zoom link to join: https://weizmann.zoom.us/j/92234357805?pwd=aVkrR21CSUVtVS9tSEJYRDkwOFRidz09 Meeting ID: 922 3435 7805 Password: 648092
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    Technologies for all-optical interrogation of neural circuits in behaving animalsTechnologies for all-optical interrogation of neural circuits in behaving animals

    Date:
    25
    Tuesday
    May
    2021
    Lecture / Seminar
    Time: 12:30
    Lecturer: Dr. Adam Packer
    Organizer: Department of Brain Sciences
    Details: Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: Neural circuits display complex spatiotemporal patterns of activity on the milli ... Read more Neural circuits display complex spatiotemporal patterns of activity on the millisecond timescale during behavior. Understanding how these activity patterns drive behavior is a fundamental problem in neuroscience, and remains a major challenge due to the complexity of their spatiotemporal dynamics. The ability to manipulate activity in genetically defined sets of neurons on the millisecond timescale using optogenetics has provided a powerful new tool for making causal links between neuronal activity and behavior. I will discuss novel approaches that combine simultaneous two-photon calcium imaging and two-photon targeted optogenetic photostimulation with the use of a spatial light modulator (SLM) to provide ‘all-optical’ readout and manipulation of the same neurons in vivo. This approach enables reading and writing of activity in neural circuits with single-cell resolution and single action potential precision during behavior. I will describe the power, limitations and future potential of this approach; and discuss how it can be used to address many important problems in neuroscience, including transforming our search for the neural code and the links between neural circuit activity and behavior. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Heat Shock Factor 1-dependent extracellular matrix remodeling mediates the transition from chronic intestinal inflammation to colon cancer

    Date:
    27
    Tuesday
    April
    2021
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Oshrat Galibov-Levi
    Organizer: Department of Biomolecular Sciences
    Abstract: In the colon, long-term exposure to chronic inflammation drives colitis-associat ... Read more In the colon, long-term exposure to chronic inflammation drives colitis-associated colon cancer (CAC). However, molecular understanding of how this occurs is still lacking. Within the tumor, cancer cells are surrounded by a variety of non-malignant cells and by the extracellular matrix (ECM), which together compose the tumor microenvironment (TME), which is essential for tumor homeostasis and progression. While the cancer cells are highly mutated, the stromal cells are genomically stable. Master regulator heat shock factor 1 (HSF1) was shown to play an important part in the transcriptional reprogramming of the TME. By using proteomic and advanced methods of microscopy and image analysis we show that HSF1-dependent ECM remodeling plays a crucial role in mediating inflammation-driven colon cancer. /j/95881429481?pwd=VkxwUmg1Z2ErZmhpZDJqMTZwellGZz09
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    Atmospheric Dynamics on Jupiter: New Results from the Juno Mission

    Date:
    22
    Thursday
    April
    2021
    Colloquium
    Time: 11:15-12:30
    Location: https://weizmann.zoom.us/j/94477142638?pwd=aWNlZGVzNmdJdnJVZVNZUi9sZ0VBZz09
    Lecturer: Yohai Kaspi
    Organizer: Faculty of Physics
    Abstract: NASA's Juno Mission is now completing its 5 year nominal mission around Jupiter, ... Read more NASA's Juno Mission is now completing its 5 year nominal mission around Jupiter, orbiting the planet in an eccentric polar-orbit every 53 days. One of the prime mission objectives is better understanding the atmospheric dynamics through gravitational, microwave, infrared and magnetic measurements. In this talk, we will focus on three new results explaining different aspects of the dynamics on Jupiter. First, infrared imaging data revealed that Jupiter’s poles are surrounded by 5 cyclones around the North Pole and 8 cyclones around the South Pole. We explain the location, size and stability of these circumpolar cyclones based on vorticity dynamics. Second, using microwave data, revealing Jupiter’s deep ammonia abundance structure, we show that Jupiter has 8 meridional circulation cells in each hemisphere. These cells resemble in their governing physics Earth's midlatitude Ferrel cells, and relate to the observed red and white belts and zones at Jupiter’s cloud-level. Finally, using Juno’s gravity measurements we constrain the depth of Jupiter’s east-west jet-streams, and the depth (mass) of the most iconic vortex in the Solar system — Jupiter’s Great Red Spot. Overall, this unique multiple instrument dataset allows now explaining the governing physics of several outstanding aspects of Jupiter’s internal and atmospheric dynamics. We will also compare the dynamics to those of Saturn, generalizing some of the this new understanding.
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    Cellular and circuit basis of distinct memory formation in the hippocampus

    Date:
    06
    Tuesday
    April
    2021
    Lecture / Seminar
    Time: 12:30
    Lecturer: Dr. Christoph Schmidt-Hieber
    Organizer: Department of Brain Sciences
    Details: Zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUd ... Read more Zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: Formation and retrieval of distinct memories are complementary processes that pu ... Read more Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Solving computational problems with coupled lasers

    Date:
    18
    Thursday
    March
    2021
    Colloquium
    Time: 11:15-12:30
    Location: https://weizmann.zoom.us/j/94477142638?pwd=aWNlZGVzNmdJdnJVZVNZUi9sZ0VBZz09
    Lecturer: Nir Davidson
    Organizer: Faculty of Physics
    Abstract: Computational problems may be solved by realizing physics systems that can simul ... Read more Computational problems may be solved by realizing physics systems that can simulate them. Here we present a new system of coupled lasers in a modified degenerate cavity that is used to solve difficult computational tasks. The degenerate cavity possesses a huge number of degrees of freedom (300,000 modes in our system), that can be coupled and controlled with direct access to both the x-space and k-space components of the lasing mode. Placing constraints on these components are mapped on different computational minimization problems. Due to mode competition, the lasers select the mode with minimal loss to find the solution. We demonstrate this ability for simulating XY spin systems and finding their ground state, for phase retrieval, for imaging through scattering medium, and more.
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    Using Ultra-High Field MRI to Study the Human Brain

    Date:
    04
    Thursday
    March
    2021
    Lecture / Seminar
    Time: 09:00-10:00
    Location: ZOOM
    Lecturer: Dr. Edna Furman-Haran and Dr. Tali Weiss
    Organizer: Department of Life Sciences Core Facilities

    Room Temperature 13C-DNP in Diamond Powder

    Date:
    18
    Thursday
    February
    2021
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Dr. Daphna Shimon
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Link: Zoom: https://weizmann.zoom.us/j/91742036303?pwd=cWJuOFBEZUpYU3p6bHBj ... Read more Zoom Link: Zoom: https://weizmann.zoom.us/j/91742036303?pwd=cWJuOFBEZUpYU3p6bHBjUEduRllxdz09 Passcode: 771770 Electron and nuclear spins in diamond have long coherence and relaxation times at room temperature, making them a promising platform for applications such as biomedical and molecular imaging and nanoscale magnetic field sensing. While the optically-active nitrogen-vacancy (NV) defect has received a great deal of attention, the substitutional nitrogen (or P1) center also exhibits long coherence and relaxation times. These P1 centers are typically present at significantly larger concentrations (about an order magnitude larger) than NVs, allowing us to explore the role of P1-P1 interactions in mediating DNP. The system can, in principle, show DNP via the solid effect (SE), cross effect (CE) and Overhauser effect (OE) depending on the P1 concentration and the field. Here, we show enhancement of natural abundance 13C nuclei found within the diamond, using the unpaired electron of the P1 center (concentration 110-130 ppm) in particles with a 15-25 μm diameter, under static conditions at room temperature and 3.4 T. We discuss the DNP spectrum, the active DNP mechanisms and what we can learn about the diamond powder from DNP.
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    Crystallization Mechanisms: Classical, Nonclassical, and Beyond

    Date:
    08
    Monday
    February
    2021
    Colloquium
    Time: 11:00-12:00
    Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09
    Lecturer: Prof. Boris Rybtchinski
    Organizer: Faculty of Chemistry
    Abstract: Understanding how order evolves during crystallization represents a long-standin ... Read more Understanding how order evolves during crystallization represents a long-standing challenge. We will describe our recent studies on crystallization of organic molecules and proteins by cryo-TEM imaging and cryo-STEM tomography. They reveal mechanisms, in which order evolution proceeds via diverse pathways, including various intermediate states. Based on these findings, we suggest a general outlook on molecular crystallization.
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    Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization”.

    Date:
    31
    Sunday
    January
    2021
    Lecture / Seminar
    Time: 11:00-12:00
    Lecturer: Prof. Talila Volk
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWF ... Read more Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWFhZVUVzZz09 The genetic material of live organisms is packed and stored within the nucleus. It contains DNA wrapped around the nucleosomes, which then organized into chromatin fibers that partition into distinct compartments, which eventually fill the entire nucleus. Chromatin three dimensional topology is essential for proper accessibility of transcription factors, which control tissue-specific gene expression programs. Whereas chromatin partition into specific domains has been described in cells in culture conditions, information regarding chromatin 3 dimensional distribution in tissues within live organisms is still missing. We have imaged the chromatin in muscle fibers of live, intact Drosophila larvae, and revealed its 3 dimensional structure. Our results demonstrate novel 3 dimensional architecture of the chromatin which is evolutionary conserved, and has important implications on the regulation of gene expression.
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    “Low-field MRI: new perspectives”

    Date:
    28
    Thursday
    January
    2021
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Prof. Najat Salameh
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom: Link: https://weizmann.zoom.us/j/98957854014?pwd=ZTEyazd6cThxUE90L3ZJbkdkb ... Read more Zoom: Link: https://weizmann.zoom.us/j/98957854014?pwd=ZTEyazd6cThxUE90L3ZJbkdkbkFWQT09 passcode: 159170 Magnetic Resonance Imaging (MRI) is a non-ionizing, non-invasive imaging modality that has become key in modern medicine. Its high value resides in a broad range of soft tissue contrasts or biomarkers that can be tuned to enable the identification and follow-up of many pathophysiological or metabolic processes. Such developments were made possible thanks to almost forty years of hardware and software development, yet access to MRI nowadays remains exclusive, bound to radiology suites in hospitals, and restricted to less than half of the world population. This limited accessibility is mostly due to its one-fits-all design and its prerequisites for intense magnetic field strength that impact cost, siting infrastructure, and clinical compatibility. One way to improve accessibility in MRI is to lower the magnetic field strength that will naturally influence cost, siting, and compatibility. Further, lowering the field strength can translate in smaller footprint designs which geometry and contrast could purposely be tuned to certain targeted applications. Indeed, relaxation mechanisms are known to change with the surrounding magnetic field, with larger T1 dispersion at low field that have for the most part been unexplored. Although very promising, many challenges arise linked to the lower intrinsic nuclear spin polarization inherent to low field technologies, calling for original and innovative approaches to reach clinical relevance. During this seminar, Prof. Najat Salameh will describe those challenges and possible solutions by presenting the current landscape of low field imaging and recent progress made at the Center for Adaptable MRI Technology, Basel University.
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    Layers of primary visual cortex as a window into internal models about predicted and simulated environments

    Date:
    26
    Tuesday
    January
    2021
    Lecture / Seminar
    Time: 12:30-13:30
    Lecturer: Prof. Lars Muckli
    Organizer: Department of Brain Sciences
    Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: Normal brain function involves the interaction of internal processes with incomi ... Read more Normal brain function involves the interaction of internal processes with incoming sensory stimuli. We have created a series of brain imaging experiments (using 7T fMRI) that sample internal models and feedback mechanisms in early visual cortex. Primary visual cortex (V1) is the entry-stage for cortical processing of visual information. We can show that there are 3 information counter-streams concerned with: (1) retinotopic visual input, (2) top-down predictions of internal models generated by the brain, and (3) top-down imagery acting independently of the perception and prediction loop. Internal models amplify and disamplify incoming information, but there is also mental imagery not interfering with visual perception. Our results speak to the conceptual framework of predictive coding. Healthy brain function will strike a balance between the precision of prediction and prediction update based on prediction error. Our results incorporate state of the art, layer-specific ultra-high field fMRI and other imaging techniques. We argue that fMRI with its capability of measuring dendritic energy consumption is sensitive to activity in different parts of layer spanning neurons, enriching our computational understanding of counter stream brain mechanisms. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Marine electrical imaging reveals novel freshwater transport mechanism in Hawaiʻi

    Date:
    26
    Tuesday
    January
    2021
    Lecture / Seminar
    Time: 11:00
    Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09
    Lecturer: Eric Attias
    Organizer: Department of Earth and Planetary Sciences
    Abstract: Conventional hydrogeologic models employed to compute ocean island sustainable y ... Read more Conventional hydrogeologic models employed to compute ocean island sustainable yields and aquifer storage neglect the nearshore and onshore submarine environment’s complexity. However, the onshore aquifer at the island of Hawaiʻi exhibits a significant volumetric discrepancy between high-elevation freshwater recharge and coastal discharge. This study presents a novel transport mechanism of freshwater moving from onshore to onshore via a multilayer formation of water-saturated layered basalts with interbedded low-permeability layers of ash/soil, as revealed by marine-controlled source electromagnetic (CSEM) imaging. We propose that this newly discovered transport mechanism of fresh water may be the governing mechanism in other volcanic islands. Additionally, our water column CSEM imaging detects multiple vertical freshwater plumes extending from the seafloor to the ocean surface. These findings provide valuable information to elucidate hydrogeologic and oceanographic rocesses affecting biogeochemical cycles in coastal waters worldwide.
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    New perspectives on interlayer excitons in two-dimensional heterostructures

    Date:
    19
    Tuesday
    January
    2021
    Lecture / Seminar
    Time: 18:00-19:00
    Lecturer: Dr. Ouri Karni
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCaz ... Read more Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCazNwZz09 Two-dimensional layered (van-der-Waals) heterostructures, made by stacking different monolayers of semiconducting transition-metal dichalcogenides, have been drawing much attention as versatile platforms for studying fundamental solid-state phenomena and for designing opto-electronic devices. Interlayer excitons, electron-hole pairs that bind to each other across the interlayer spacing in these heterostructures, hold promise as key tools for probing the interlayer interface structure, and for exploring many-body interactions(1). With long lifetimes, spin polarization, and electric tunability, interlayer excitons are also promising as flexible information carriers(2, 3). However, they were mostly studied through the scope of their visible light emission, missing essential properties such as their momentum-space image or their absorption strength, necessary for rigorous study of their many-body interactions and potential applications. In this talk I will present our recent studies aimed at measuring such unknown interlayer exciton properties and their dependence on the heterostructure. I will show a new interlayer exciton in WSe2/MoS2 heterostructures which we discovered based on its light emission in infra-red wavelengths, rather than in the visible range(4). I will demonstrate its properties as inferred from its optical interrogation. Then, I will present the quantitative measurement of the elusive optical absorption spectrum of interlayer excitons using electric-field modulation spectroscopy, essential for coherent coupling of light to those excitons(5). Finally, I will reveal how time- and angle-resolved photoemission spectroscopy is used to image the interlayer exciton in momentum-space, yielding its size and binding energy, so far inaccessible through optics(5).
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    Vision and Robotics Seminar

    Date:
    14
    Thursday
    January
    2021
    Lecture / Seminar
    Time: 12:15-13:30
    Title: Next generation localization microscopy - or - how and why to ruin a perfectly good microscope
    Lecturer: Yoav Shechtman
    Organizer: Faculty of Mathematics and Computer Science,Department of Computer Science and Applied Mathematics,Department of Mathematics
    Details: In localization microscopy, the positions of individual nanoscale point emitters ... Read more In localization microscopy, the positions of individual nanoscale point emitters (e.g. fluorescent molecules) are determined at high precision from their point-spread functions (PSFs). This enables highly precise single/multiple-particle-tracking, as well as super-resolution microscopy, namely single molecule localization microscopy (SMLM). To obtain 3D localization, we employ PSF engineering – namely, we physically modify the standard PSF of the microscope, to encode the depth position of the emitter.
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    Abstract: In localization microscopy, the positions of individual nanoscale point emitters ... Read more In localization microscopy, the positions of individual nanoscale point emitters (e.g. fluorescent molecules) are determined at high precision from their point-spread functions (PSFs). This enables highly precise single/multiple-particle-tracking, as well as super-resolution microscopy, namely single molecule localization microscopy (SMLM). To obtain 3D localization, we employ PSF engineering – namely, we physically modify the standard PSF of the microscope, to encode the depth position of the emitter. In this talk I will describe how this method enables unprecedented capabilities in localization microscopy
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    ‘Identification of Dynamic Components in the Liquid-Liquid Phase Separation of CPEB4 by EPR Spectroscopy’

    Date:
    14
    Thursday
    January
    2021
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Dr. Manas Seal
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Link: https://weizmann.zoom.us/j/96046369379?pwd=emp0U0wwcmpNQlhsMisrNmp0bjRDdz ... Read more Link: https://weizmann.zoom.us/j/96046369379?pwd=emp0U0wwcmpNQlhsMisrNmp0bjRDdz09 Passcode: 693143 The molecular mechanisms and associated structures and dynamics of liquid-liquid phase separation (LLPS) proteins that form membrane-less organelles in cells have attracted considerable interest in recent years. EPR spectroscopy along with site directed spin labelling (SDSL) using nitroxide spin labels is a well-established technique to study dynamics of proteins. In this seminar I will discuss the dynamic properties of the spin labelled low complexity N-terminal domain of cytoplasmic polyadenylation element binding-4 protein (CPEB4NTD) in its LLPS and non-LLPS states. We found the coexistence of three CPEB4NTD populations with distinct spin label rotational correlation times before and after LLPS. We identified population I as the predominant protein species in the dilute phase, with fast motions that agree with expected dynamic properties of monomeric CPEB4NTD. We assigned population III to a compact ensemble that undergo slow motions, and population II to a looser ensemble experiencing intermediate motions. LLPS, which took place with increasing temperature is associated with increased population of II at the expense of III, while population I remains constant. At the end based on these findings, I will present a three-component equilibrium model that postulates the existence of LLPS-competent CPEB4NTD species (II and III) prior to macroscopic phase separation.
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    Diffusion properties of intracellular metabolites: compartment specific probes for cell structure and physiology

    Date:
    05
    Tuesday
    January
    2021
    Lecture / Seminar
    Time: 12:30-13:30
    Lecturer: Prof. Itamar Ronen
    Organizer: Department of Brain Sciences
    Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invas ... Read more Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invasive investigations of tissue microstructure, and provides quantitative cytomorphological information on a spatial scale well below the nominal resolution of MRI. The main limitation of DWI is its lack of compartmental specificity, as its “reporter molecule” is water, ubiquitous in all tissue compartments and cell types. Brain metabolites are mostly confined to the intracellular space, and their concentrations vary across cell types. Several metabolites give rise to quantifiable magnetic resonance spectroscopy (MRS) signatures, and are thus considered as compartment-specific and sometimes cell-specific markers. Sensitization of MRS to diffusion results in a set of diffusion properties for a variety of intracellular metabolites, from which microstructural information specific to the intracellular space can be obtained. A proper choice of experimental settings can be used to investigate properties that range from cytoplasmic viscosity and tortuosity of the intracellular space, to overall cell morphological features. The specificity of some metabolites to different cell types such as neurons and astrocytes opens the way to studying morphological properties of different cell populations and monitoring their modulation by physiological changes in health and disease. The presentation will introduce methodological concepts of diffusion-weighted MRS, followed by simple examples that demonstrate the unique ability of diffusion-weighted MRS to characterize cell-type specific structural features. Special emphasis will be bestowed on experimental and modelling frameworks that merge the specificity of diffusion-weighted MRS with the sensitivity of DWI to gain insights on tissue microstructure beyond what each method can separately provide. Zoom link to join:https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Nanoinclusions in diamonds: trapped fluids and solid molecular N2 and CO2

    Date:
    05
    Tuesday
    January
    2021
    Lecture / Seminar
    Time: 11:00
    Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09
    Lecturer: Oded Navon
    Organizer: Department of Earth and Planetary Sciences
    Abstract: Diamonds are perfect boxes for delivering samples of fluids and volatile species ... Read more Diamonds are perfect boxes for delivering samples of fluids and volatile species from the mantle to the surface. While mineral inclusions are often a few >30 micrometer in size and allow easy analysis, fluid inclusions are mostly
    Close abstract

    From design to optical properties in colloidal semiconductor nanocrystals

    Date:
    28
    Monday
    December
    2020
    Colloquium
    Time: 11:00-12:00
    Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09
    Lecturer: Prof. Dan Oron
    Organizer: Faculty of Chemistry
    Abstract: Colloidal semiconductor nanocrystals have turned over the past three decades fro ... Read more Colloidal semiconductor nanocrystals have turned over the past three decades from a scientific curiosity to a component in numerous commercial products, particularly in displays, lighting and light detection. On the one hand these are complex chemically synthesized entities, and on the other they behave, in many senses, as ‘giant’ artificial atoms. The interplay between these two enables us to imbue them with unique optical properties by design of their internal structure. I will go over some of our recent efforts in utilizing designer nanocrystals for various applications, including luminescence upconversion (the conversion of two low energy photons into a single high energy photon), electric field sensing and optical gain. Finally, I will discuss opportunities for the development of colloidal sources of non-classical states of light and our recent advances in quantum spectroscopy, enabling to study the optical and electronic properties of single quantum dots with unprecedented precision.
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    Chemosignals are a form of human social communication

    Date:
    24
    Thursday
    December
    2020
    Lecture / Seminar
    Time: 15:00-16:00
    Lecturer: Eva Mishor (PhD Thesis Defense)
    Organizer: Department of Brain Sciences
    Details: Zoom link to join: https://weizmann.zoom.us/j/98031517872?pwd=U0EvNG5EdGJBL24zW ... Read more Zoom link to join: https://weizmann.zoom.us/j/98031517872?pwd=U0EvNG5EdGJBL24zWmpKUlY1akdnZz09 Meeting ID: 980 3151 7872 Password: 976632
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    Abstract: Although animals are known to heavily rely on chemical signals for intraspecies ... Read more Although animals are known to heavily rely on chemical signals for intraspecies communication, the matter of human chemical communication remains greatly contentious. I will present evidence supporting the claim that humans, just like other animals, rely on bodily-odors to effectively navigate the social world. First, I will present a quantification of people’s overt olfactory-sampling behavior. Of approximately 400 respondents, 94% acknowledged engaging in smelling their close relationships, and approximately 60% acknowledged sniffing strangers. Next, we tested if this olfactory information is employed for socially-relevant behavioral decisions, such as trust, a key element in human socialization. We found that subliminal exposure to body-odor increased implicit trustworthiness attributed to anthropomorphic non-humans. Finally, I will describe the effect of a specific body-volatile, Hexadecanal (HEX), on human impulsive aggression. Using validated behavioral paradigms, we observed a remarkable dissociation: sniffing HEX blocked aggression in men, but triggered aggression in women. Using functional brain imaging, we uncovered a pattern of brain activity mirroring behavior: In both men and women, HEX increased activity in an area implicated in the perception of social cues. Hex then modulated functional connectivity in a brain network implicated in aggressive behavior in a sex-dependent manner. Altogether, the thesis puts forward the hypothesis that chemosignals are a form of human social communication. Under this premise, human sampling behavior of self and others’ body-volatiles provides one with important information that, in turn, affects behaviors central to human society, such as trust and aggression. Zoom link to join: https://weizmann.zoom.us/j/98031517872?pwd=U0EvNG5EdGJBL24zWmpKUlY1akdnZz09 Meeting ID: 980 3151 7872 Password: 976632
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    Behavioural signatures of a developing neural code

    Date:
    22
    Tuesday
    December
    2020
    Lecture / Seminar
    Time: 12:30-13:30
    Lecturer: Prof. Lilach Avitan
    Organizer: Department of Brain Sciences
    Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Abstract: During early life the neural code must develop to appropriately transform sensor ... Read more During early life the neural code must develop to appropriately transform sensory inputs into behavioural outputs. However little is known about how developments in neural representations directly impact on behaviour. By combining behavioural analysis with 2-photon calcium imaging at multiple timepoints from 4 to 15 dpf in the optic tectum of developing zebrafish larvae, we demonstrate a link between the maturity of neural coding in the visual brain and developmental changes in visually-guided behavior. We show that visually-driven hunting behavior improves from 4 to 15 days post-fertilization, becoming faster and more accurate. During the same period population activity in parts of the optic tectum refines, improving decoding and information transmission for particular spatial positions. Together these results show that developmental signatures of an emerging neural code can be directly related to observable properties of behaviour. Please click the link below to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070
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    Zoom lecture: Nanoscale Optical Imaging Of Individual And Densely Packed Microgel Colloids

    Date:
    06
    Sunday
    December
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Lecturer: Prof. Frank Scheffold
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Link: https://weizmann.zoom.us/j/95267372668?pwd=dEhvRlA3SGtvVTQ1QnVmZ3JJ ... Read more Zoom Link: https://weizmann.zoom.us/j/95267372668?pwd=dEhvRlA3SGtvVTQ1QnVmZ3JJdTZEQT09 Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles uniquely. This study explores the frequency-dependent linear viscoelastic properties of dense suspensions of micron-sized microgels in conjunction with an analysis of the local particle structure and morphology-based on superresolution microscopy. By identifying the dominating mechanisms that control the elastic and dissipative response, we can explain these widely studied soft particle assemblies' rheology. Interestingly, our results suggest that the polymer brush-like corona's lubrification reduces friction between the microgel contacts.
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    How cells determine their volume

    Date:
    30
    Monday
    November
    2020
    Colloquium
    Time: 11:00-12:00
    Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09
    Lecturer: Prof. Sam Safran
    Organizer: Faculty of Chemistry
    Abstract: Living cells regulate their volume using a diverse set of mechanisms, to maintai ... Read more Living cells regulate their volume using a diverse set of mechanisms, to maintain their structural and functional integrity. The most widely-used mechanism to control cell volume is active ion transport. Experiments on adhered cells surprisingly revealed that their volume is significantly reduced as their basal area is increased1. We have developed a physical theory2 which considers both electrostatics and cell activity to predict a generic relation for how adhered cells regulate their volume in response to changes in their area, in agreement with the observations. Those measurements also show that the nuclear volume scales with the cell volume. Recently, the Volk group3 using intact-organism imaging, discovered that changes in nuclear volume dramatically varies the spatial organization of chromatin (DNA and associated proteins); this may have important consequences for gene expression. A simple polymeric model4 that includes the competition of chromatin self-attraction and interactions with the nuclear membrane, predicts transitions in the chromatin organization relative to the nucleus from peripheral to central to conventional, as the nuclear volume is reduced, as measured in the experiments of the Volk group.
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    Love thy neighbor - unraveling the tumor microenvironment by multiplexed imaging

    Date:
    17
    Tuesday
    November
    2020
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Leeat Keren
    Organizer: Department of Biomolecular Sciences
    Abstract: Tumors are spatially organized ecosystems that are comprised of distinct cell ty ... Read more Tumors are spatially organized ecosystems that are comprised of distinct cell types, each of which can assume a variety of phenotypes defined by coexpression of multiple proteins. To underscore this complexity, and move beyond single cells to multicellular interactions, it is essential to interrogate cellular expression patterns within their native context in the tissue. We have pioneered MIBI-TOF (Multiplexed Ion Beam Imaging by Time of Flight), a platform that enables simultaneous imaging of forty proteins within intact tissue sections at subcellular resolution. In this talk, I will describe our application of multiplexed imaging to study the tumor immune microenvironment in triple negative breast cancer. Our work reveals archetypical organizations, linking molecular expression patterns, cell composition and histology, which are predictive of patient survival.
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    Recent Advances in Flow and Imaging Flow Cytometry

    Date:
    05
    Thursday
    November
    2020
    Lecture / Seminar
    Time: 09:00-10:00
    Title: Features
    Location: https://weizmann.zoom.us/j/96479787051?pwd=cGx2eHhNeEc3WE9sbnV1ZW1oYWI2QT09
    Lecturer: Dr. Ziv Porat
    Organizer: Department of Life Sciences Core Facilities

    Zoom lecture: Quantum sensor assisted magnetic resonance

    Date:
    15
    Thursday
    October
    2020
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Prof. Ashok Ajoy
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Details: Yeda Research and Development Ltd. is the commercial branch of the Weizmann Inst ... Read more Yeda Research and Development Ltd. is the commercial branch of the Weizmann Institute of Science. Yeda holds an exclusive right to commercialize the unique intellectual property developed by the scientists at the Weizmann Institute.
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    Abstract: Nuclear magnetic resonance (NMR) spectroscopy, is renowned for its high chemic ... Read more Nuclear magnetic resonance (NMR) spectroscopy, is renowned for its high chemical specificity, but suffers from low sensitivity and poor spatial resolution. This has largely locked up NMR in “central facilities”, where the measurement paradigm involves taking the sample to the NMR spectrometer. We are innovating a class of optical NMR probes that can allow one to invert this paradigm, effectively bringing the NMR spectrometer into the sample. This would open possibilities for NMR probes of analytes in their local environment. These “deployable” NMR sensors rely on a uniquely optically addressable spin platform constructed out of nanoparticles of diamonds, hosting defect centers (NV centers) and 13C nuclei. Such electron-nuclear spin hybrids serve dual-roles as optical “polarization injectors” and optical NMR detectors while also being targetable to within the sample of interest. I will focus on the main ingredients of this technology, while alluding to potential frontier applications opened as a result. Zoom link: https://weizmann.zoom.us/j/98496818322?pwd=RW03TWtTUUpKYXBXQlJtbnprMTRKdz09 passcode: 888482
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    Visualizing Strongly-Interacting Quantum Matter

    Date:
    24
    Thursday
    September
    2020
    Colloquium
    Time: 11:15-12:30
    Location: https://weizmann.zoom.us/j/92790893230?pwd=VlRjVzkvaGZ5YWRvcXFGWXVXZ3dXdz09
    Lecturer: Shahal Ilani
    Organizer: Faculty of Physics
    Abstract: When quantum mechanics and Coulomb repulsion are combined in a pristine solid, s ... Read more When quantum mechanics and Coulomb repulsion are combined in a pristine solid, some of the most fascinating electronic phases in nature can emerge. Interactions between electrons can form correlated insulators, electronic liquids, and in extreme cases even quantum electronic solids. These phases are predicted to exhibit their most striking features in real-space, however, they are also extremely fragile, preventing their visualization with existing experimental tools. In this talk, I will describe our experiments that use a pristine carbon nanotube as a new type of a scanning probe, capable of imaging electrical charge with unprecedented sensitivity and minimal invasiveness. I will show how using this platform we were able to obtain the first images of the quantum crystal of electrons, visualize the collective hydrodynamic flow of interacting electrons in graphene, and unravel the parent state that underlies the physics of strongly-interacting electrons in the recently-discovered system of magic angle twisted bilayer graphene.
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    Reversing personalized medicine

    Date:
    10
    Thursday
    September
    2020
    Lecture / Seminar
    Time: 13:30-14:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Gal Markel
    Organizer: Department of Immunology and Regenerative Biology
    Details: the link for the lecture's zoom room https://weizmann.zoom.us/j/5065402023?pwd= ... Read more the link for the lecture's zoom room https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09
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    Abstract: Personalized medicine in oncology is focused on fitting drugs to the appropriat ... Read more Personalized medicine in oncology is focused on fitting drugs to the appropriate patients, mainly by identifying unique mutations in tumor genomics and development of highly selective drugs. The main challenge is that the relevant populations grow smaller, while development costs are constant, leading to significant reduction in effective drug development. The immune system provides personalized anti cancer response, and immune checkpoint inhibitors enable decent responses over a wide array of tumors. The outstanding challenge is that efficacy is observed in less than a third of the patients. Here we explore strategies to alter the patient in a way that will enable standard of care immunotherapy to exert its full potential, i.e. fitting the patients to the existing immunotherapeutic medications.
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    Microscopy and Spectroscopic Imaging of Nanostructures

    Date:
    03
    Thursday
    September
    2020
    Conference
    Time: 08:00-18:00
    Location: Gerhard M.J. Schmidt Lecture Hall

    Structure Sensitivity in Catalysis

    Date:
    23
    Sunday
    August
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Joint special seminar of the depts. of Organic Chemistry & Materials and Interfaces
    Location: https://weizmann.zoom.us/j/95177555007?pwd=aDE5V2FVL2hRSDB5cFFuMTRQckViZz09
    Lecturer: Dr. Charlotte Vogt
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Some fundamental concepts of catalysis are as of yet not fully explained but are ... Read more Some fundamental concepts of catalysis are as of yet not fully explained but are of paramount importance for the development of improved supported metal catalysts for chemical industries and environmental remediation. Structure (in)sensitivity is such a fundamental physical concept in catalysis, which relates the rate of a catalytic reaction per unit surface area to the size of a nanoparticle. If this rate per unit surface area changes with catalyst particle size, a reaction is termed structure sensitive. Conversely if it does not - a reaction is termed structure insensitive. Historically, many fundamental physical concepts explaining the behavior of metal nanoparticular catalysts have been formulated by studying single crystal facets with surface science techniques which has left a considerable gap in our basic knowledge of catalysts at work. By using and developing state-of-the-art operando (micro)spectroscopic techniques, inter alia operando high-temperature high-pressure FT-IR, in-situ high-resolution STEM, and quick-X-ray absorption spectroscopy (quick-XAS) with millisecond time resolution, over the last few years I have been exploring the fundamental physical concepts behind fundamental structure-activity relationships of catalytic reactions by studying non-model catalysts at work. For example, by applying these methods to study a structure sensitive reaction (carbon dioxide hydrogenation) to a structure insensitive one (ethene hydrogenation) we show that the same geometric and electronic effects that we find to explain structure sensitivity make it unlikely for structure insensitivity to exist (while we do observe it empirically). However, interestingly, in the case of the structure insensitive ethene hydrogenation reaction, such size-dependent nanoparticle restructuring effects as the decrease of the reversibility of adsorbate-induced restructuring and the increase of carbon diffusion with increasing particle size are observed by quick-XAS (see Figure 1). While for the structure sensitive CO2 hydrogenation no such perturbation was observed. We further show that this particle size dependent restructuring induced by ethene hydrogenation can make a structure sensitive reaction structure insensitive. Hence, we may postulate that structure insensitive reactions should rather be termed apparently structure insensitive, which changes our fundamental understanding of the age-old empirical observation of structure insensitivity.
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    ClearSight™: A portable system that uses diffusion NMR to probe the margins of excised tumors

    Date:
    16
    Thursday
    July
    2020
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Dr. Saul Stokar
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Abstract: Zoom link: https://weizmann.zoom.us/j/91154950215?pwd=ZkRsTWJzL1AzMWpNbFVSVUF4d0 ... Read more Zoom link: https://weizmann.zoom.us/j/91154950215?pwd=ZkRsTWJzL1AzMWpNbFVSVUF4d05zQT09 Password: 388848 Diffusion NMR weighted NMR and MRI are very powerful techniques for investigating microscopic details about tissue architecture, either normal or in a diseased state. In addition to its traditional use in diagnosing stroke and ischemic injury in the brain, in recent years DWI has been used to diagnose various kinds of cancer, including breast, prostate and lung cancers. In this seminar we will present an overview of a novel portable system that uses DWI to check whether the margins of excised breast tumors are tumor-free. This is extremely important both for the patient and the hospital, since it obviates the need to perform additional surgery if the subsequent pathology indicates the presence of tumor on the margin of the excised tissue, something that occurs today in up to 25% of breast-conserving surgeries. We shall provide an overview of diffusion MRI, the unique challenges of performing MRI in or near the operating theater, the architecture of ClearCut's system, computer simulations of its performance and an overview of the clinical results obtained to date.
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    The power of ONE: Immunology in the age of single cell genomics

    Date:
    02
    Thursday
    July
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Ido Amit
    Organizer: Dwek Institute for Cancer Therapy Research

    Sparsity-based Methods for Rapid MRI

    Date:
    25
    Thursday
    June
    2020
    Lecture / Seminar
    Time: 09:30-10:30
    Lecturer: Dr. Efrat Shimron
    Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
    Abstract: Zoom Lecture: https://weizmann.zoom.us/j/99058507421 Magnetic Resonance Ima ... Read more Zoom Lecture: https://weizmann.zoom.us/j/99058507421 Magnetic Resonance Imaging (MRI) is a superb imaging modality that provides high-quality images of the human body. However, one of its major limitations is the long acquisition time, which hinders the MRI clinical use. The acquisition time can be shortened by acquiring less data; however, this requires suitable methods for accurate image reconstruction from subsampled data, which is acquired with a sub-Nyquist rate. In this seminar, four novel methods for image reconstruction from subsampled data will be presented. These methods build upon the well-established frameworks of Parallel Imaging (PI) and Compressed Sensing (CS), utilize a-priori knowledge about data sparsity, and address current limitations of PI-CS methods. The first two methods accelerate static MRI scans by introducing the Convolution-based Reconstruction (CORE) framework, which offers a parameter-free non-iterative reconstruction. Experiments with in-vivo 7T brain data demonstrated that these methods perform comparably to the well-established GRAPPA and l1-SPIRiT methods, with the advantage of shorter computation times and reduced need for parameter calibration. The next two developed methods accelerate dynamic MRI scans that provide temperature monitoring in High Intensity Focused Ultrasound (MRgHIFU) thermal ablation treatments. The developed methods enable rapid MR monitoring by reconstructing temperature changes from subsampled data. Validation experiments were performed with in-vivo data from clinical treatments of prostate cancer in humans; these showed that the proposed methods significantly outperform two state-of-the-art methods in the temperature reconstruction task
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    Vesicle membrane ‘quarantine’ by mechanochemical insulation maintains apical membrane homeostasis during exocytosis

    Date:
    16
    Tuesday
    June
    2020
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Kamalesh Kumari
    Organizer: Department of Biomolecular Sciences
    Abstract: Exocrine glands in our bodies secret copious amounts of cargo (like- sweat, sali ... Read more Exocrine glands in our bodies secret copious amounts of cargo (like- sweat, saliva, digestive enzymes, chemokines, etc.) via. giant secretory vesicles, that are micron-scale in diameter. During the secretion of these giant vesicles, a large amount of the membrane is constantly added to the apical surface of the cells that can perturb its size, composition, and function that are vital to cell survival. Hemostatic maintenance of the cell surface in terms of size, shape, and composition is extremely challenging in the face of continuous secretion, which what we ventured to understand. We use a combination live-cell imaging and correlative light and electron microscopy (CLEM) approach, to uncover a novel a mechanism of exocytosis allowing the secretory cells to maintain membrane homeostasis during secretion. I will present to you data to describe what we call as - the crumpling and sequestration model of exocytosis.
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    Cancer Research Club - Prof Dan Landau: Novel genomics perspectives on cancer evolution: from basic principles to therapeutic optimization

    Date:
    04
    Thursday
    June
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Dan Landau
    Organizer: Department of Immunology and Regenerative Biology

    Mass Photometry – a new way to study biomolecules

    Date:
    02
    Tuesday
    June
    2020
    Lecture / Seminar
    Time: 10:00-10:45
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Adar Sonn-Segev
    Organizer: Department of Biomolecular Sciences
    Abstract: One of the main challenges of researchers that utilize purified proteins for in- ... Read more One of the main challenges of researchers that utilize purified proteins for in-vitro assays is the characterization of the purity and heterogeneity of their proteins in solution. To find out this information, you can employ native gel electrophoresis, gel-filtration chromatography, dynamic light scattering or mass spectroscopy. While some of these methods have low resolution and require large amounts of protein, others are time consuming and require a lot of knowledge to operate and interpret. Mass photometry is a new ground-breaking tool to analyze biomolecules. It is based on interferometric scattering microscopy and enables the accurate mass measurement of single molecules in solution, in their native state without the need for labels, and provides results within minutes. It provides a rapid, accurate and simple analysis of the oligomeric state of proteins in solution. In fact, mass photometry offers optimal conditions for studying sample heterogeneity, protein-protein and protein-nucleic acid interactions, protein oligomerization, macromolecular assemblies many more. Mass photometry represents a truly novel approach for the analysis of individual biomolecules in solution. I will illustrate the unique capabilities of mass photometry by discussing a broad selection of recently published examples and provide insight into the strengths and limitations of this approach. * Weizmann Institute has collaborated with Refeyn Ltd to make mass photometry available to all Weizmann research community, with an on-site specialist, Dr. Adar Sonn-Segev, to help with its implementation.
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    Chemistry Colloquium

    Date:
    11
    Monday
    May
    2020
    Colloquium
    Time: 11:00-12:15
    Title: The Macromolecular Structure of Mucus, Our Bodies’ First Line of Defense Against Pathogens
    Location: https://weizmann.zoom.us/j/92049901272
    Lecturer: Prof. Debbie Fass
    Organizer: Faculty of Chemistry
    Abstract: Respiratory viruses such as coronavirus spread from person to person through dro ... Read more Respiratory viruses such as coronavirus spread from person to person through droplets of saliva or mucus. Face masks decrease the dissemination of such droplets and thereby minimize viral propagation from someone who may be contagious. Mucus did not evolve, though, to help pathogens spread. Quite the opposite. Mucus arose early in the evolution of multicellular animals to exclude undesirable bacteria from body tissues, a primitive type of immunity. The cooperation between cilia* and mucus also helped prevent aquatic organisms from being smothered by sediments and enabled them to clean or collect particulate matter from their exteriors. Producing mucus was likely a prerequisite for evolution of the gut and of the types of respiratory organs necessary for terrestrial life. Today, mucus protects the large, exposed interior surfaces of our respiratory and gastrointestinal tracts from bacteria, viruses, parasites, and chemical/physical hazards. But what material is mucus? Mucus is a hydrogel made of heavily glycosylated protein molecules called “mucins,” each of which is nearly 3 megadaltons in size. Individual giant mucin molecules are disulfide bonded to one another, generating an extended mesh. Using cryo-electron microscopy and X-ray crystallography, we have discovered the three-dimensional structure of mucins and gained insight into the mechanism by which they assemble step-wise into hydrogels. ______________________________________________________ * cell-surface, rope-like structures that beat in coordinated waves
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    Canceled: Nanoscale Electronic Phenomena in Ferroelectric Thin Films

    Date:
    18
    Wednesday
    March
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Alexei Gruverman
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: This seminar consists of two parts. The first part is related to the investigati ... Read more This seminar consists of two parts. The first part is related to the investigation of mechanism of tunable domain wall (DW) conductivity in the ferroelectric LiNbO3 thin films with sub-µm thickness, Using a combination of scanning transmission electron microscopy (STEM) and local probe techniques we generate and delineate the electrically-charged 180º DWs and test their conducting behavior using local probe spectroscopy and imaging under electrical bias. More importantly, electrical tunability of DW conductivity by sub-coercive voltage is realized through the changes in DW conformity. The obtained results provide tangible evidence that the charged DWs can be used as multilevel logic elements in analog computing devices. The second part discusses the dynamic switching behavior in the HfO2-based films investigated by a combination of local probe microscopy and pulse switching techniques. Application of HfO2-based materials to ferroelectric memory and logic devices has generated considerable interest as they allow overcoming significant problems associated with poor compatibility of perovskite ferroelectrics with CMOS processing. High-resolution studies of the time- and field-dependent evolution of the domain structure in La:HfO2 thin film capacitors provides an insight into the mechanism of imprint - one of the main degradation effects hindering integration of ferroelectric HfO2 into CMOS-compatible memory technology.
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    Recovering Lost Information in the Digital World

    Date:
    15
    Sunday
    March
    2020
    Lecture / Seminar
    Time: 13:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Yonina Eldar, WIS
    Organizer: Department of Physics of Complex Systems
    Abstract: The conversion of physical analog signals to the digital domain for further proc ... Read more The conversion of physical analog signals to the digital domain for further processing inevitably entails loss of information.The famous Shannon-Nyquist theorem has become a landmark in analog to digital conversion and the development of digital signal processing algorithms. However, in many modern applications, the signal bandwidths have increased tremendously, while the acquisition capabilities have not scaled sufficiently fast. Furthermore, the resulting high rate digital data requires storage, communication and processing at very high rates which is computationally expensive and requires large amounts of power. In this talk, we present a framework for sampling and processing a wide class of wideband analog signals at rates far below Nyquist by exploiting signal structure and the processing task. We then show how these ideas can be used to overcome fundamental resolution limits in optical microscopy, ultrasound imaging, quantum systems and more. We demonstrate the theory through several demos of real-time sub-Nyquist prototypes and devices operating beyond the standard resolution limits combining high spatial resolution with short integration time.
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    MR spectroscopy at 7 tesla – initial experiences in Glasgow

    Date:
    05
    Thursday
    March
    2020
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr Graeme Keith
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Much has been written of the potential of ultra-high field MR scanners, such as ... Read more Much has been written of the potential of ultra-high field MR scanners, such as 7 tesla, due to their inherently higher signal-to-noise ratio (SNR). This native boost is of great use in making techniques that operate in a low SNR regime, such as spectroscopy, more viable. Application of spectroscopic techniques at 7 tesla also come with a secondary, yet perhaps more important benefit in increased spectral resolution. This can allow for the quantitative investigation of metabolites that are difficult to resolve and measure reliably at lower field strengths. This seminar will relate early experiences in spectroscopy from the Siemens Terra 7T system at the University of Glasgow. This will include the optimisation of single voxel techniques for clinical studies, such as the measurement of glutamate in neuroinflammatory conditions, as well as an update on development work, such as a spectral 2D correlated spectroscopy (COSY) acquisition for investigation of glioma tumours, including a focus on 2-hydorxyglutarate. It will also cover the development of a novel MR spectroscopic imaging (MRSI) technique based on the EPSI sequence, which will allow for high resolution, full spectral bandwidth 7T acquisitions in a clinically viable time, by application of compressed sensing methods
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    From Cognition to Depression: Using Magnetic Resonance Spectroscopy to Study In-vivo Neurochemistry

    Date:
    03
    Tuesday
    March
    2020
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Assaf Tal
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance wit ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concent ... Read more Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concentrations of several metabolites in the brain non-invasively. I will present our work using MRS to study two aspects of brain metabolism. First, I'll talk about our work on functional MRS, whereby we look at neurochemical changes during or after learning or function. In the second half of the talk, I will focus on new methods we're developing in the lab, and in particular on our ability to measure the thermal relaxation times of metabolites, which probe specific cellular and subcellular microenvironments. I will present some preliminary data showing where and how this could be useful.
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    The Biological Age Concept: Predicting Healthspan and Lifespan using Genomics, Epigenomics and Proteomics from Saliva and Plasma

    Date:
    27
    Thursday
    February
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Guest Talk with Prof Jaap Goudsmit
    Lecturer: Prof. Jaap Goudsmit
    Organizer: Department of Molecular Cell Biology
    Details: The Biological Age Concept: Predicting Healthspan and Lifespan using Genomics, E ... Read more The Biological Age Concept: Predicting Healthspan and Lifespan using Genomics, Epigenomics and Proteomics from Saliva and Plasma Jaap Goudsmit, MD, PhD Departments of Immunology & Infectious Diseases and Epidemiology, Harvard T.H. Chan School of Public Health The moment the first age-related disease manifests itself defines healthspan, like the moment of death does for lifespan. Lifespan and healthspan are impacted by mutations in a set of genetic loci as well as series of events afterwards impacting epigenetic changes downregulating the transcription of DNA to RNA (DNAm) or the translation of RNA to protein (microRNAs). Age, like sex, impacts lifespan most during life as a marker independent from individual age-related diseases. The length of the period after the healthspan ends is characterized by a stochastic accumulation of morbidities that each in combination or on their own can shorten lifespan. Biological age can be viewed as a metric defining the link between healthspan and lifespan. The best algorithm for biological age includes a combination of organ system markers including a marker for deterioration of the brain, which we call “Biosystem Age”, calibrated on the stringency of predicting lifespan independent of chronological age. Biosystem Age predicts healthspan as well as individual age-related diseases better than chronological age and has a very specific age-related microRNA signature. We propose that each change of events or genetic pathway during life that at first hand appears to be associated with disease or death rates is heavily influenced by Biosystem Age. We plan to test whether immune responsiveness to vaccines declining with age is dependent of Biosystem Age.
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    Chemical Biology Seminar Series

    Date:
    27
    Thursday
    February
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Title: In Vivo Chemical Probes for MRI and Fluorescence Imaging
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Kazuya Kikuchi
    Organizer: The Dr. Barry Sherman Institute for Medicinal Chemistry

    Assurance of Clonality Next-Generation Single-Cell Dispensing in Cell Line Development and Single-Cell Genomics

    Date:
    24
    Monday
    February
    2020
    Lecture / Seminar
    Time: 10:00-11:00
    Title: Presentation & ‘Cytena f.sight’ hands-on
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Adrian Zambrano
    Organizer: Department of Life Sciences Core Facilities

    Looking into the rocks of Acheulo-Yabrudian Qesem Cave (Israel, 420-200 kya)

    Date:
    20
    Thursday
    February
    2020
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Aviad Agam
    Organizer: Academic Educational Research
    Abstract: The Acheulo-Yabrudian Cultural Complex (AYCC, ~420,000-200,000 years ago) is a l ... Read more The Acheulo-Yabrudian Cultural Complex (AYCC, ~420,000-200,000 years ago) is a local Levantine entity, characterized by a set of innovative human cultural and biological adaptations, including the habitual use of fire, technological innovations such as blade and Quina scraper production, and more. Qesem Cave (QC, central Israel) is one of the key sites of the AYCC. I will present the results of two recent studies, exploring the rich lithic assemblages yielded from this important site. The first combines macroscopic classification of flint artefacts with a geological survey and petrographic and geochemical analyses, aimed at identifying patterns of flint acquisition and use. The results show that local Turonian flint was often brought and used at the cave, while flint from other, non-Turonian origins, was also used in noteworthy proportions, in specific categories, implying selectivity in flint procurement and exploitation through time. The second study combines Raman spectroscopy and artificial intelligence (AI) to build temperature predictive models, aimed at identifying the temperatures to which flint artefacts were exposed. The results show that blades were heated at lower median temperatures (259℃) compared to flakes (413℃), suggesting the intentional and controlled heat treatment of flint specifically for blade production, more than 300,000 years ago. Both datasets and their implications will be discussed in a broader perspective.
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    M.Sc thesis defense: "The origin of anharmonic atomic motion in halide perovskite crystals"

    Date:
    13
    Thursday
    February
    2020
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Adi Cohen
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Halide perovskites (ABX3) attracted much of attention in the last years due to t ... Read more Halide perovskites (ABX3) attracted much of attention in the last years due to their excellent photovoltaic activity. They are unique in the sense that they exhibit long carrier lifetime despite having many apparent structural defects. Recent studies in our group concluded that this unique behavior is due to strong coupling between the electronic band structure and the strongly anharmonic motion of the atoms within the crystal. Therefore, it is imperative to understand the source of anharmonic atomic motion in this class of materials. Studies have indicated the B-cation lone pair to be a possible source for strong anharmonic behavior in the perovskite crystals. In order to understand the anharmonic behavior and its origin, I investigated a series of perovskites with different lone pair stereoactivity. Using low frequency Raman spectroscopy, I quantified the level of anharmonicity and determined the influence of the B-cation lone pair on the structural dynamics.
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    The Genomics of Fasting and Inflammation Reveals Dynamic Cooperativity Between Transcription Factors

    Date:
    09
    Sunday
    February
    2020
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Ido Goldstein
    Organizer: Life Sciences

    The earliest evidence of a Lisfranc’s fracture

    Date:
    06
    Thursday
    February
    2020
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Sara Borgel
    Organizer: Academic Educational Research
    Abstract: Recent archaeological excavations at Manot Cave, an Early Upper Palaeolithic sit ... Read more Recent archaeological excavations at Manot Cave, an Early Upper Palaeolithic site in the Western Galilee, Israel, retrieved the remains of a partial left foot of a young adult, including the talus, the calcaneus, the cuboid and the first, second and fifth metatarsals. The pedal remains were found close to one another, in the same archaeological unit, and were associated with an Early Upper Palaeolithic assemblage. Our study aimed at describing the anatomy of the Manot Cave pedal bones using morphometric parameters. A comparison to foot bones of recent modern humans, Anatomically Modern Humans and Neanderthals was carried out to establish the Manot Cave specimen population affiliation. Additionally, µCT images were used to verify a suspected injury in the base of the second metatarsal. The shape and size of the Manot pedal bones indicated a modern morphology for all bones, albeit few Neanderthal-like characteristics. Imaging analysis confirmed the existence of a healed trauma in the second metatarsal, with the plantar third of the base misaligned with the shaft and a fracture line on the lateral side. These features are consistent with a fracture known as Lisfranc’s fracture, most probably caused by an impact to the dorsum of the foot. This injury usually leads to ligamentous instability and collapse of the transverse and longitudinal arches, causing severe walking difficulties. Full recovery requires rest and immobility for several weeks. As mobility was crucial to maintain the hunter-gatherer lifeway of this group, the survival of this individual indicates a supportive community at Manot Cave.
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    Whole-brain fMRI of the Behaving Mouse

    Date:
    04
    Tuesday
    February
    2020
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Itamar Kahn
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance wit ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Functional MRI is used pervasively in human brain research, enabling characteriz ... Read more Functional MRI is used pervasively in human brain research, enabling characterization of distributed brain activity underlying complex perceptual and cognitive processes. However, heretofore this technique has been limited in utility in rodents. I will present whole-brain functional imaging of head-fixed mice performing go/no-go odor discrimination in a platform allowing precise odor-delivery system, non-invasive sniff recordings and lick detection, detailing the brain regions subserving this behavior from the naïve state to task proficiency including learning of rule reversal. I will briefly discuss efforts to expand the mouse fMRI platform to additional modalities and conclude by describing the prospects of this approach more broadly.
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    Imaging single cells in live models for neurodevelopmental and sleep disorders

    Date:
    28
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Lior Applebaum
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For accessibility ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Chemical and Biological Physics Dept Seminar

    Date:
    28
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 11:00
    Title: Wide-Field Single Photon-Counting Imaging for Fast and Highly Sensitive In Vivo Cell Tracking
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr Rinat Ankri
    Organizer: Department of Chemical and Biological Physics
    Abstract: Biomolecular imaging at the preclinical stage is an essential tool in various bi ... Read more Biomolecular imaging at the preclinical stage is an essential tool in various biomedical research areas such as immunology, oncology or neurology. Among all modalities available to date, optical imaging techniques play a central role, while fluorescence, in particular in the NIR region of the spectrum, provides high sensitivity and high specificity with relatively cheap instrumentation. Several whole-body optical pre-clinical NIR imaging systems are commercially available. Instruments using continuous wave (CW or time-independent) illumination allow basic small animal imaging at low cost. However, CW techniques cannot provide fluorescence lifetime contrast, which allows to probe the microenvironment and affords an increased multiplexing power. In the first part of my talk I will introduce our single photon, time-gated, phasor-based fluorescence lifetime Imaging method which circumvents limitations of conventional techniques in speed, specificity and ease of use, using fluorescent lifetime as the main contrast mechanism. In the second part of my talk I will present the tracking and multiplexing of two different cell populations, based on their different lifetimes (following their fluorescent dyes-loading). Despite major advantages of optical based NIR imaging, the reason that NIR imagers are not clinically used, is that only very few such fluorescent molecules absorb and emit in the NIR (or in the shortwave infrared, SWIR region), and even fewer have favorable biological properties (and FDA approval). I will introduce small lung cancer and dendritic cells tracking using small polyethylene glycol/phosphatidylethanolamine (PEG–PE) micelles loaded with NIR dyes (using commercial dyes as well as dyes synthesized in Prof. Sletten’s lab, UCLA Chemistry Dept.). Micelles’ endocytosis into cells affords efficient loading and exhibits strong bio stability, enabling to track the loaded cells for several days using these formulations, even though dyes were diluted by cells division (leading to reduced dye concentration within the dividing cells). Moreover, fluorescent lifetime contrast (achieved through our time-gated imaging method), significantly improved these cells detection. These advances in NIR fluorescence based imaging open up new avenues toward NIR and SWIR imaging for biomedical applications, such as tracking and monitoring cells during immunotherapy and/or drug delivery (treatment monitoring) for various types of disease.
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    Catalyst Images, Imaging and Imagination: Visualizing Molecules and Atoms in Action on Catalytic Surfaces

    Date:
    28
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Prof. Bert M. Weckhuysen
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Catalysts play a pivotal role in modern society since they enable the production ... Read more Catalysts play a pivotal role in modern society since they enable the production of chemicals and fuels that we rely on every day. The search for new and improved solid catalysts to speed up and access novel chemical reactions is a never-ending challenge, but has become increasingly important due to the environmental challenges that we are currently facing. For this purpose, constant improvements in synthesis methods are required in general, but more specifically, improvements in characterization methods in terms of spatiotemporal resolution is the key toward tailored catalytic reactions. In an ideal case, a real time visualization of the reactants, intermediates and reaction products on the surface of the catalyst is possible, allowing for a molecular movie of the catalytic reaction in space and time. Certain characterization techniques exist that are sensitive enough to measure the reactants at the reaction surface of the catalyst (e.g. vibrational spectroscopy). However, in order to really understand the catalytic behaviour, we need to move toward single molecules and atoms at the (sub-) nanometer scale. Improvements in this direction have already led to an increased understanding of the catalytic processes, but the combination of nanometer resolution in space and pico- to nanosecond resolution in time has remained largely elusive in the world of heterogeneous catalysis.  In this lecture, I will discuss the state-of-the-art of time- and space-resolved spectroscopy and microscopy methods for catalysis research, and discuss the movement in the field toward the visualization of individual molecules at catalyst surfaces to construct the ultimate “molecular movie of sustainability” (Figure 1). Special emphasis will be on the compatibility of operando characterization techniques with the desired reaction environment (e.g. liquid or gas phase) and what we can do to ensure the spatiotemporal resolution is not hampered by the reaction requirements of the catalytic reactions. I will touch upon a variety of techniques, ranging from (time-resolved and surface-enhanced) vibrational spectroscopy, single molecule fluorescence, scanning probe techniques combined with optical and vibrational spectroscopy, as well as X-ray spectroscopy and microscopy.
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    Chemical and Biological Physics Guest Seminar

    Date:
    26
    Sunday
    January
    2020
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Non-Genetic “Optogenetics”: Silicon Based Bio-Interfaces for Multi-scale Optical Modulation
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr Menahem (Hemi) Rotenberg
    Organizer: Department of Chemical and Biological Physics
    Abstract: Bioelectronics for cellular interrogation requires a minimally invasive introduc ... Read more Bioelectronics for cellular interrogation requires a minimally invasive introduction of an electrical probe to the cell. Despite tremendous developments in the field of electroceuticals in the past decades, the available technologies are still associated with major limitations. Micropipette electrodes, micro- and nanoelectrode arrays, and nano-field effect transistors allow intracellular access with extremely high spatial resolution. However, these technologies are substrate-bound, do not allow reconfigurable recording or stimulation, and lack deep tissue access, which limits their use to in vitro application. Optogenetics can offer numerous mechanistic insights into cellular processes, but its spatial resolution is limited, especially for 3D tissues. Moreover, it requires genetic modification, which limits its potential therapeutic applications. In this talk, I will present my recent studies of developing new approaches for bio-interfaces using silicon micro- and nanostructures for non-genetic optical modulation, spanning from sub cellular interrogation with extremely high spatial resolutions to whole organ optical modulation. For sub-cellular interrogation, we used tailored made photovoltaic silicon nanowires with p-i-n core-shell design. These nanowires were hybridized with living myofibroblasts and used as free sanding cell-silicon hybrids with leadless optical modulation capabilities. We used focused laser to perform intracellular electrical interrogation with high, sub-cellular spatial resolution. Thereafter, we used these hybrids to tackle a long-standing debate regarding electrical coupling between myofibroblasts and cardiomyocytes in vivo, by interrogating specific myofibroblasts within the 3D volume of the cardiac tissue. We also show this technology’s utility for neuronal investigation by hybridizing myelinating oligodendrocytes and interfacing them with neurons, allowing the investigation of calcium transients’ role in the myelination process with unprecedented spatial control. For whole organ interface we used flexible single crystalline silicon membranes, that were able to adhere and wrap around the heart and sciatic nerve. We used optical stimulation to perform heart pacing at different location on the heart, and sciatic nerve excitation. These results demonstrate potential biomedical applications for cardiac resynchronization therapy and sciatic nerve neuro-regenerative treatments.
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    Visualizing activity dependent signaling dynamics in intact neuronal circuits

    Date:
    21
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Tal Laviv
    Organizer: Department of Brain Sciences
    Details: Joint Seminar-Depts of Neurobiology & Biomolecular Sciences Hosts: Prof. Ro ... Read more Joint Seminar-Depts of Neurobiology & Biomolecular Sciences Hosts: Prof. Rony Paz rony.paz@weizmann.ac.il tel: 6216 (Neurobiology) Prof. Rivka Dikstein rivka.dikstein@weizmann.ac.il tel: 2117 (Biomolecular Sciences) For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Sensory experience can change the structure and function of neurons in the bra ... Read more Sensory experience can change the structure and function of neurons in the brain over a wide range of timescales, from milliseconds-second modulation of synaptic activity to long-lasting alterations of genetic programs, lasting minutes to hours. While conversion of synaptic activity into long-lasting nuclear signaling is vital for learning and neuronal development, we still lack a clear understanding of its basic operating principles. To address this, I will describe recent advancements using two-photon fluorescence lifetime imaging and new biosensors which allowed us to image the activity of CREB, an activity-dependent transcription factor important for synaptic plasticity, at single cell resolution in awake mice. Simultaneous imaging of CREB and Ca2+ in the visual cortex permitted us to explore how sensory deprivation (dark-rearing) can modulate the sensitivity and duration of CREB activity to sensory-evoked Ca2+ elevations. Future work using this approach will allow us to unravel synapse to nucleus signaling dynamics underlying experience-dependent plasticity in the brain.
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    Visualizing activity dependent signaling dynamics in intact neuronal circuits

    Date:
    21
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 12:30-13:30
    Title: Joint Seminar - Dept. of Neurobiology & Biomolecular Sciences
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Tal Laviv - Joint Seminar - Dept. of Neurobiology & Biomolecular Sciences
    Organizer: Department of Biomolecular Sciences
    Abstract: Sensory experience can change the structure and function of neurons in the brain ... Read more Sensory experience can change the structure and function of neurons in the brain over a wide range of timescales, from milliseconds-second modulation of synaptic activity to long-lasting alterations of genetic programs, lasting minutes to hours. While conversion of synaptic activity into long-lasting nuclear signaling is vital for learning and neuronal development, we still lack a clear understanding of its basic operating principles. To address this, I will describe recent advancements using two-photon fluorescence lifetime imaging and new biosensors which allowed us to image the activity of CREB, an activity-dependent transcription factor important for synaptic plasticity, at single cell resolution in awake mice. Simultaneous imaging of CREB and Ca2+ in the visual cortex permitted us to explore how sensory deprivation (dark-rearing) can modulate the sensitivity and duration of CREB activity to sensory-evoked Ca2+ elevations. Future work using this approach will allow us to unravel synapse to nucleus signaling dynamics underlying experience-dependent plasticity in the brain.
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    Soil Spectroscopy throughout the Years: Availabilities and Capabilities

    Date:
    19
    Sunday
    January
    2020
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Eyal Ben-Dor
    Organizer: Department of Earth and Planetary Sciences
    Abstract: The soil spectroscopy discipline has been progressed over the past two decades q ... Read more The soil spectroscopy discipline has been progressed over the past two decades quite remarkably. Many portable point spectrometers became available through that time where recently also image spectrometers have become quite popular. The technology was used in the laboratory, field, and airborne levels and provided a new capability for a rapid and quantitative view of a large number of samples. At the same time platforms were also developed to carry the new family of sensors for remote sensing applications of large areas using ground and airborne vehicles ( manned and un-manned) and recently even satellites. This progress has led to a large number of activities in exploiting the spectroscopy for many applications within the soil science discipline. As the data acquisition increases and the soil spectral database has been enlarged, a new technique to compile soil spectral database together with methods to effectively analyze them has also been developed. To that end, activities to deal with the data mining process using big databases were successfully adopted from other disciplines while also designed especially for the soil spectroscopy activity. The results demonstrated that soil spectroscopy could be used for many applications from different domains such as soil mapping, precision agriculture, and laboratory work and can progress the soil science discipline quite forward. In this talk, we will review the history of soil spectroscopy from the first spectrometer and platform to the present situation. A particular emphasis will be given to the recent applications that have been developed in our group and to the future capability of this critical technology from all perspectives and to the new horizon it may open as expressed by space agencies such as NASA, ESA, ASI, JAXA, ISA and DLR.
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    From connectome to function: connectivity features underlying neuronal population dynamics in the nematode C. elegans

    Date:
    14
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Manuel Zimmer
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance w ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: A fundamental problem in neuroscience is to elucidate the relationship between n ... Read more A fundamental problem in neuroscience is to elucidate the relationship between neuronal network anatomy and its functional dynamics. The nematode worm C. elegans is an ideal model to study these problems. Its nervous system has just 302 neurons and all synaptic connections between them have been fully mapped. Using a large-scale Ca2+-imaging approach, we previously discovered nervous system wide neuronal population dynamics in the worm that encode action commands. These dynamics feature various network attractor states during which neurons coordinate and synchronize their activities, thereby providing functional interaction maps. In this talk, I will discuss unpublished work where we combine graph-theoretical and experimental approaches to understand which anatomical features in network connectivity relate to these functional dynamics and interactions between neurons.
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    Chemical and Biological Physics Guest Seminar

    Date:
    14
    Tuesday
    January
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Title: Emerging exotic quantum phenomena in 1D molecular chains on surfaces
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr Pavel Jelinek
    Organizer: Department of Chemical and Biological Physics
    Abstract: Low dimensional materials offer very interesting material and physical propertie ... Read more Low dimensional materials offer very interesting material and physical properties due to reduced dimensionality. Nowadays, mostly 2D materials are the focus of attention. However, 1D systems often show far more exotic behavior, such as Tomanaga-Luttinger liquid, Peierls distortion, etc.. In this talk, we will present different classes of 1D molecular chains formed on metallic surfaces by on-surface synthesis, which physical and chemical properties were investigated by low temperature UHV scanning probe microscopy supported by theoretical analysis. First, we will introduce a novel strategy to synthesize [1] a new class of intrinsically quasi-metallic one-dimensional (1D) -conjugated polymers featuring topologically non-trivial quantum states. Furthermore, we unveiled the fundamental relation between quantum topology, -conjugation and metallicity of polymers [2]. Thus, we will make a connection between two distinct worlds of topological band theory (condensed matter physics) and -conjugation polymer science (chemistry). We strongly believe this may stimulate new ways of thinking towards a design of novel organic quantum materials. In second part, we will demonstrate unusual mechanical and electronic properties of hydrogen bonded chains formed on a metallic surface driven by quantum nuclaar effects within the chain. We will show, that the concerted proton tunneling not only enhances the mechanical stability of the chain, but it also gives rise to new in-band gap electronics states localized at the ends of the chain. [1] A. Grande-Sanchez et al. Angew. Chem. Int. Ed. 131, 6631-6635 (2019). [2] B. Cierra et al arXiv preprint arXiv:1911.05514
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    Chemical and Biological Physics Guest Seminar

    Date:
    12
    Sunday
    January
    2020
    Lecture / Seminar
    Time: 14:00
    Title: Allosteric signal propagation studied by transient IR spectroscopy
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Peter Hamm
    Organizer: Department of Chemical and Biological Physics

    Denise Cai: Linking memories across time and by Tristan Shuman: Breakdown of spatial coding and interneuron synchronization in epileptic mice

    Date:
    09
    Thursday
    January
    2020
    Lecture / Seminar
    Time: 14:30-15:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Denise Cai and Tristan Shuman
    Organizer: Department of Brain Sciences
    Details: Back-to-back Talk (1-hour long in total) Host: Prof. Nachum Ulanovsky nachum. ... Read more Back-to-back Talk (1-hour long in total) Host: Prof. Nachum Ulanovsky nachum.ulanovksy@weizmann.ac.il tel: 6301 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Denise Cai: Linking memories across time The compilation of memories, collecte ... Read more Denise Cai: Linking memories across time The compilation of memories, collected and aggregated across a lifetime defines our human experience. My lab is interested in dissecting how memories are stored, updated, integrated and retrieved across a lifetime. Recent studies suggest that a shared neural ensemble may link distinct memories encoded close in time. Using in vivo calcium imaging (with open-source Miniscopes in freely behaving mice), TetTag transgenic system, chemogenetics, electrophysiology and novel behavioral designs, we tested how hippocampal networks temporally link memories. Multiple convergent findings suggest that contextual memories encoded close in time are linked by directing storage into overlapping hippocampal ensembles, such that the recall of one memory can trigger the recall of another temporally-related memory. Alteration of this process (e.g. during aging, PTSD, etc) affect the temporal structure of memories, thus impairing efficient recall of related information. Tristan Shuman: Breakdown of spatial coding and interneuron synchronization in epileptic mice Temporal lobe epilepsy causes severe cognitive deficits yet the circuit mechanisms that alter cognition remain unknown. We hypothesized that the death and reorganization of inhibitory connections during epileptogenesis may disrupt synchrony of hippocampal inhibition. To test this, we simultaneously recorded from CA1 and dentate gyrus (DG) in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between CA1 and DG in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit using a novel wire-free Miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This place cell instability emerged ~6 weeks after status epilepticus, well after the onset of chronic spontaneous seizures and interneuron death. Finally, our CA1 network model showed that desynchronized inputs can impair information content and stability of CA1 place cells. Together, these results demonstrate that temporally precise intra-hippocampal communication is critical for spatial processing and hippocampal desynchronization contributes to spatial coding deficits in epileptic mice.
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    Imaging deep: sensory and state coding in subcortical circuits

    Date:
    09
    Thursday
    January
    2020
    Lecture / Seminar
    Time: 11:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Jan Grundemann
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Yaniv Ziv yaniv.ziv@weizmann.ac.il tel: 4275 For assistance with ... Read more Host: Dr. Yaniv Ziv yaniv.ziv@weizmann.ac.il tel: 4275 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Internal states, including affective or homeostatic states, are important behavi ... Read more Internal states, including affective or homeostatic states, are important behavioral motivators. The amygdala is a key regulator of motivated behaviors, yet how distinct internal states are represented in amygdala circuits is unknown. Here, by longitudinally imaging neural calcium dynamics across different environments in freely moving mice, we identify changes in the activity levels of two major, non-overlapping populations of principal neurons in the basal amygdala (BA) that predict switches between exploratory and non-exploratory (defensive, anxiety-like) states. Moreover, the amygdala broadcasts state information via several output pathways to larger brain networks, and sensory responses in BA occur independently of behavioral state encoding. Thus, the brain processes external stimuli and internal states orthogonally, which may facilitate rapid and flexible selection of appropriate, state-dependent behavioral responses.
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    Intricate Assembly Mechanism of Mucin Glycoproteins Revealed by Cryo-electron Microscopy of Polymers

    Date:
    31
    Tuesday
    December
    2019
    Lecture / Seminar
    Time: 14:30-15:00
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Gabriel Javitt
    Organizer: Department of Chemical and Structural Biology

    Physical Genomics Harnessing physics and chemistry for single-molecule analysis of the human genome

    Date:
    30
    Monday
    December
    2019
    Lecture / Seminar
    Time: 14:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Yuval Ebenstein, TAU
    Organizer: Department of Physics of Complex Systems
    Abstract: DNA is an amazing memory device that holds the operating system of life. However ... Read more DNA is an amazing memory device that holds the operating system of life. However, DNA sequencing fails to extract the full range of information associated with genetic material and is lacking in its ability to resolve variations between genomes. As a consequence, many genomic features remain poorly characterized in the human genome reference. In addition, the information content of the genome extends beyond the base sequence in the form of chemical modifications such as DNA methylation or DNA damage lesions that chemically encode our life experiences in our DNA. By applying experimental principles of single molecule detection we gain access to the structural variation and long range patterns of genetic and epigenetic information. We show how physical extension of long DNA molecules on surfaces and in nanofluidic channels reveals such information in the form of a linear, optical “barcode” showing distinct types of observables. Recent results from our lab demonstrate our ability to detect epigenetic marks and various forms of DNA damage on individual genomic DNA molecules and use this information for medical diagnostics.
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    Hyperactive FOXA1 Signaling in Breast Cancer Endocrine Resistance and Metastasis - When Genomics Meet Epigenomics

    Date:
    26
    Thursday
    December
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Max and Lillian Candiotty Building
    Lecturer: Dr. Rachel Schiff
    Organizer: Department of Immunology and Regenerative Biology

    The Large Synoptic Survey Telescope: Status Update and Prospects for Science

    Date:
    26
    Thursday
    December
    2019
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Steven M. Kahn
    Organizer: Faculty of Physics
    Details: 11:00 - Coffee, Tae and more
    Abstract: The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field groun ... Read more The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field ground-based telescope designed to provide a time-domain imaging survey of the entire southern hemisphere of sky in six optical colors (ugrizy). Over ten years, LSST will obtain ~ 1,000 exposures of every part of the southern sky, enabling a wide-variety of distinct scientific investigations, ranging from studies of small moving bodies in the solar system, to constraints on the structure and evolution of the Universe as a whole. The development of LSST is a collaboration between the US National Science Foundation, which is supporting the development of the telescope and data system, and the US Department of Energy, which is supporting the development of the 3.2 gigapixel camera, the largest digital camera ever fabricated for astronomy. Approved in 2014, LSST is now well into construction, and is on track to beginning operations in 2022. I will review the design and technical status of the Project, and provide an overview of some of the exciting science highlights that we expect to come from this facility.
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    Simulating the whole of magnetic resonance

    Date:
    19
    Thursday
    December
    2019
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Ilia Kuprov
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: In a couple of years from now, we will finish kernel programming for Spinach – ... Read more In a couple of years from now, we will finish kernel programming for Spinach – a spin dynamics simulation library that supports all types of magnetic resonance spectroscopy, from Gd3+ DEER, through DNP and NMR, and all the way to singlet state diffusion MRI, including chemical kinetics, optimal control, and advanced relaxation theories. This level of generality hinges on: 1. The ability to treat classical degrees of freedom (diffusion, hydrodynamics, radiofrequency and microwave phases, stochastic tumbling, etc.) at the same conceptual level as spin degrees of freedom – the corresponding classical equations of motion must be integrated into the density matrix formalism. 2. The ability to survive enormous Kronecker products. A well digitised medical phantom would have at least a hundred points in each of the three directions, meaning a dimension of at least 1003 = 106 for the spatial dynamics generator matrices. At the same time, a typical radical contains upwards of ten coupled spins, meaning a Liouville space dimension of at least 410. Direct products of spin and spatial dynamics generators would then have the dimension in excess of 1012 even before chemical kinetics is considered. 3. Code parallelisation over cluster architectures, including the possibility of using a GPU on each node of the cluster. The principal problem is parallelisation mode switching between powder averages, indirect dimensions of pulse sequences, frequency points of frequency domain simulations, etc. – each simulation type would in general require a different mode of parallelisation and GPU utilisation. This report is about solving all of this, and on where the dark art of simulating a time-domain magnetic resonance experiment stands at the moment. Two recent innovations are the abandonment of Liouville equation in favour of Fokker-Planck equation as the core formalism, and the use of tensor structured objects that never open Kronecker products. A separate story is recent GPUs: NVidia Tesla V100 performs ~1013 double-precision multiplications per second – an astounding amount of computing power that is surprisingly easy to use.
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    Decipher the properties of sex-shared yet dimorphic neuronal circuits

    Date:
    18
    Wednesday
    December
    2019
    Lecture / Seminar
    Time: 15:15
    Location: The David Lopatie Hall of Graduate Studies
    Lecturer: Vladyslava Pechuk (MSc Thesis Defense/PhD Proposal)
    Organizer: Department of Brain Sciences
    Abstract: The nervous system of sexually reproducing species is built to accommodate their ... Read more The nervous system of sexually reproducing species is built to accommodate their sex-specific needs and thus contains sexually dimorphic properties. Males and females respond to environmental sensory cues and transform the input into sexually dimorphic traits. New findings reveal a significant difference in the way the two sexes in the nematode C. elegans respond to aversive stimuli. Further analysis of the function of the circuit for aversive behaviors unveiled how stimuli elicit non-dimorphic sensory neuronal activity, proceeded by dimorphic postsynaptic interneuron activity, generating the sexually dimorphic behavior. Here, we propose to uncover how genetic sex defines the properties of the sex-shared circuit for aversive behaviors. We will explore the circuit at the behavioral, connectome and genetic levels. Using calcium imaging, optogenetics, synaptic trans-labeling, transcriptome profiling and a candidate gene approach we will map the functional connections and define the dimorphic responses of all the cells in the avoidance circuit in both sexes. Since in vertebrates and invertebrates, males and females share most of the nervous system, studies of the development of dimorphic aspects of the shared nervous system are crucial for understanding the effects of sex on brain and behavior and specifically, how do changes in connectivity generate dimorphic behaviors, and how both are modulated by the genetic sex.
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    At the Interface between Organic and Inorganic Matter: Interactions and Design of Simple Functional Coatings

    Date:
    18
    Wednesday
    December
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Meital Reches
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Several natural processes are mediated by the interactions between organic and ... Read more Several natural processes are mediated by the interactions between organic and inorganic materials. The immune response towards an implant inserted into the body is mediated by proteins. Composite materials are formed by the interactions of organic materials (usually proteins) and minerals. Biofouling, the process in which organisms attached to surfaces, is also mediated by organic molecules. Understanding the nature of interactions between organic and inorganic materials will bring to the development of improved implants, new composites and antifouling materials. This lecture will present single-molecule force spectroscopy measurements of the interactions between individual biomolecules (either amino acid residues or short peptides) and inorganic surfaces in aqueous solution. Using this method, we were able to measure low adhesion forces and could clearly determine the strength of interactions between individual amino acid residues and inorganic substrates. Our results with peptides also shed light on the factors that control the interactions at the organic-inorganic interface. Based on our knowledge from single molecule experiments, we designed a short peptide (tripeptide) that can spontaneously form a coating that resists biofilm formation. Our results clearly demonstrate the formation of a coating on various surfaces (glass, titanium, silicon oxide, metals and polymers). This coating prevents the first step of antifouling, which involves the adsorption of bioorganic molecules to the substrate. In addition, it significantly reduces the attachment of various organisms such as bacteria and fungi to surfaces. Another variation of this peptide can encourage the adhesion of mammalian cells while preventing biofilm formation.
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    In vivo multimodality imaging of immune-vascular interactions in cardiovascular disease

    Date:
    12
    Thursday
    December
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Katrien Vandoorne
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Cardiovascular disease is a result of genetic and environmental risk factors tha ... Read more Cardiovascular disease is a result of genetic and environmental risk factors that together generate arterial and cardiac pathologies. Blood vessels connect multiple organ systems throughout the entire body allowing organs to interact via circulating messengers. Multimodality imaging achieves integration of these interfacing systems’ distinct processes, quantifying interactions that contribute to cardiovascular disease. Noninvasive multimodality imaging techniques are emerging tools that can further our understanding of this complex and dynamic interplay. Multichannel multimodality imaging including optics, CT, PET and MRI, are particularly promising because they can simultaneously sample multiple biomarkers. As the opportunities provided by imaging expand, mapping interconnected systems will help us decipher the complexity of cardiovascular disease and monitor novel therapeutic strategies.
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    Spatial Transcriptomics: A getting started guide to the 10x genomics Visium Spatial Gene expression Solution

    Date:
    03
    Tuesday
    December
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Nicola Cahill
    Organizer: Department of Life Sciences Core Facilities
    Abstract: The Visium Spatial Gene Expression Solution from 10x Genomics analyzes complete ... Read more The Visium Spatial Gene Expression Solution from 10x Genomics analyzes complete transcriptomes in intact tissue sections, allowing you to discover genes and markers relevant to your research without having to rely on known targets. Preserving spatial resolution offers critical information for understanding the relationships between cellular function, phenotype, and location in the tissue.
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    Attosecond Interferometry

    Date:
    28
    Thursday
    November
    2019
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Nirit Dudovich
    Organizer: Faculty of Physics
    Details: 11:00 Coffee, Tae and more
    Abstract: Attosecond science is a young field of research that has rapidly evolved over th ... Read more Attosecond science is a young field of research that has rapidly evolved over the past decade. The progress in this field opened a door into a new area of research that allows one to observe multi-electron dynamics in atoms, molecules and solids. One of the most important aspect of attosecond spectroscopy lies in its coherent nature. Resolving the internal coherence is a primary challenge in this field, serving as a key step in our ability to reconstruct the internal dynamics. As in many other branches in physics, coherence is resolved via interferometry. In this talk, I will describe advanced schemes for attosecond interferometry. The application of these schemes provides direct insights into a range of fundamental phenomena in nature, from tunneling and photoionization in atomic systems to ultrafast chiral phenomena in molecules.
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    Preclinical Imaging using Electron Paramagnetic Resonance

    Date:
    28
    Thursday
    November
    2019
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Boris Epel
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Electron Paramagnetic Resonance (EPR) Imaging is a well-established method for t ... Read more Electron Paramagnetic Resonance (EPR) Imaging is a well-established method for the study of spatial distribution and local environment of electron paramagnetic centers and spin probes. One of the most important applications of modern EPR imaging is in vivo oximetry in which soluble spin probes with oxygen-dependent relaxation rates are used. Partial oxygen pressure (pO2) levels in tumors are major determinants of the response to cancer therapy. I will present the results of the in vivo oxygen guided radiation targeting study. This study combines pO2 images and conformal radiation delivery using 3D-printed blocks to achieve high precision treatment of tumor hypoxic areas. The study demonstrates that the dose to well-oxygenated tumor volumes in fibrosarcoma tumors in mice can be considerably reduced without compromising the outcome.
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    Application of Electron Crystallography Methods in Metallurgy

    Date:
    20
    Wednesday
    November
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Louisa Meshi
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Due to the direct correlation among the physical properties and crystal structur ... Read more Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.
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    Dynamic functional organization of midbrain dopamine neurons during complex behavior

    Date:
    19
    Tuesday
    November
    2019
    Lecture / Seminar
    Time: 12:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Ben Engelhard
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance w ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Dopamine is an essential neurotransmitter in brain that has been implicated in m ... Read more Dopamine is an essential neurotransmitter in brain that has been implicated in many devastating brain conditions and associated behavioral deficits, including working memory deficits in Parkinson's disease, motivational deficits in schizophrenia, attention deficits in ADHD and more. However, in contrast to the variety of functions clinically attributed to dopamine, the neurobiological literature has considered dopamine neurons to be mainly involved in reward processing, raising the question of how a diverse array of functions can be accounted for by such a limited behavioral role. The involvement of ventral tegmental area (VTA) dopamine neurons in reward processing and learning has been firmly shown using Pavlovian conditioning or simple cue-reward association behaviors; in those experiments, dopamine neurons behaved as a functionally homogenous population dopamine activity in more complex behaviors has been less well studied, mainly due to technical difficulties of monitoring large ensembles of genetically identified dopamine neurons during complex behavior. To overcome this gap, we performed new experiments of dopamine function by combining a novel technique for studying VTA dopamine neurons (2-photon calcium imaging via a GRIN lens) with a complex behavioral assay (navigation-based decision making in virtual reality). We show that during complex behavior, dopamine neurons divide into distinct, anatomically organized, functional subpopulations that mediate different aspects of the behavior (Engelhard et al., Nature 2019). This newfound functional diversity of dopamine neurons offers a novel view of the behavioral role of dopamine: rather than consisting of a single functional block, dopamine neurons may flexibly encode a diverse array of behavioral variables via distinct functional subpopulations that emerge in response to behavioral demands.
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    Application of Electron Crystallography Methods in Metallurgy

    Date:
    13
    Wednesday
    November
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Louisa Meshi
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Due to the direct correlation among the physical properties and crystal structur ... Read more Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.
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    Transmission Electron Microscopy in Motion

    Date:
    03
    Sunday
    November
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Frances M. Ross
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: We can watch crystals grow in the electron microscope by adding atoms one at a t ... Read more We can watch crystals grow in the electron microscope by adding atoms one at a time onto a clean surface. The movies tell us about kinetics and thermodynamics but can also be entertaining, frustrating, or both at the same time. I will attempt to share the joy of this type of “in situ” microscopy as we aim to understand how atoms assemble into nanowires or nanocrystals and use the information to control the formation of more complicated nanostructures with new properties
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    Characterization of Biomolecule and Structure Changes using Polarization Transfer from Hyperpolarized Water

    Date:
    31
    Thursday
    October
    2019
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Jihyun Kim
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool for ... Read more Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool for the characterization of protein structure and intermolecular interactions. However, NMR is not readily applicable to determine fast structural changes and weak interactions between molecules because of low signal sensitivity and time requirements to record multi-dimensional NMR spectra. To overcome these limits, the hyperpolarization technique of dissolution dynamic nuclear polarization (D-DNP) is combined with NMR. Not all molecules can be directly hyperpolarized. Instead, polarization transfer from hyperpolarized small molecules to a target of interest can be utilized as a means of obtaining polarization, as well as for detecting intermolecular interactions between these molecules Here, hyperpolarized water-assisted NMR spectroscopy was developed to measure intermolecular interactions with water. Firstly, the use of DNP hyperpolarization was demonstrated for the accurate determination of intermolecular cross-relaxation rates between hyperpolarized water and fluorinated target molecules.[1] Because hyperpolarized water acts as a source spin with a large deviation of the population from the equilibrium, the 19F signal on the target molecules is enhanced through NOE, allowing obtain an entire NOE buildup curve in a single, rapid measurement. When the hyperpolarized water-assisted NMR experiment is applied to a protein, water hyperpolarization can be transferred to amide protons on the protein through proton exchange. Further, this polarization spreads within the protein through intramolecular NOE to nearby protons including aliphatic groups.[2] By utilizing this polarization transfer, this method extends to measure enhanced 2D NMR spectra of the protein under folded and refolding conditions.[3] With the ability to rapidly measure protein signals that were enhanced through transferred polarization from hyperpolarized water, NMR spectra can be acquired within the timescale of the protein folding. Compared to the folded protein experiment, signals attributed to exchange-relayed NOEs are not observable in the refolding experiment (Figure 1b). These differences are explained by the absence of long-range contacts with nearby exchangeable protons such as OH protons
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    Mini-Symposium on Demystifying machine learning for microscopy

    Date:
    31
    Thursday
    October
    2019
    Conference
    Time: 08:00
    Location: David Lopatie Conference Centre

    Molecular Electron Microscopy for Studies on Mechanism of Molecular Motions and Reactions

    Date:
    28
    Monday
    October
    2019
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Eiichi Nakamura
    Organizer: Faculty of Chemistry

    Life Science Lectures- Recovering lost information: potential applications in biomedical research

    Date:
    03
    Thursday
    October
    2019
    Lecture / Seminar
    Time: 10:00-11:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Yonina Eldar
    Organizer: Life Sciences
    Details: Benoziyo Biochemistry Auditorium, room 191c Light refreshment will be served at ... Read more Benoziyo Biochemistry Auditorium, room 191c Light refreshment will be served at 10:40 in the lobby
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    Abstract: The conversion of physical analog signals to the digital domain for further proc ... Read more The conversion of physical analog signals to the digital domain for further processing inevitably entails loss of information. In many modern applications, the signal bandwidths have increased tremendously, while the acquisition capabilities have not scaled sufficiently fast. Furthermore, the resulting high rate digital data requires storage, communication and processing at very high rates which is computationally expensive and requires large amounts of power. In the context of medical imaging sampling at high rates often translates to high radiation dosages, increased scanning times, bulky medical devices, and limited resolution. In this talk, we present a framework for sampling and processing a wide class of wideband analog signals at rates far below the standard Nyquist rate, by exploiting signal structure and the processing task and show several demos of real-time sub-Nyquist prototypes. We consider applications of these ideas to a variety of problems including fast and quantitative MRI, wireless ultrasound, and super-resolution in microscopy and ultrasound which combines high spatial resolution with short integration time. We then show how the ideas of exploiting the task, structure and model can be used to develop interpretable model-based deep learning methods that can adapt to existing structure and are trained from small amounts of data.
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    Chemical and Biological Physics Guest Seminar

    Date:
    24
    Tuesday
    September
    2019
    Lecture / Seminar
    Time: 11:00
    Title: Probing Reactions at Electrochemical and Catalytic Interfaces with X-ray Spectroscopies
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Robert Weatherup
    Organizer: Department of Chemical and Biological Physics
    Abstract: Probing the chemical reactions occurring at electrochemical and catalytic interf ... Read more Probing the chemical reactions occurring at electrochemical and catalytic interfaces under realistic conditions is critical to selecting and designing improved materials for energy storage, corrosion prevention, and chemical production. Soft X-ray spectroscopies offer powerful element- and chemical-state-specific information with the required nm-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of interfaces under realistic liquid- and gas-phase environments.1 Here we introduce several membrane-based approaches developed in recent years in order to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid and solid-gas interfaces at atmospheric pressures.2–5 These rely on reaction cells sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber.2,3 Thin (
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    Chemical and Biological Physics Dept Special Seminar

    Date:
    15
    Sunday
    September
    2019
    Lecture / Seminar
    Time: 11:00
    Title: Single-Molecule Spectroscopy with Catalysts, Conductive Polymers, and Optical Microresonators
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Randall Goldsmith
    Organizer: Department of Chemical and Biological Physics

    Applications of Hadamard Transform in NMR Spectroscopy

    Date:
    09
    Monday
    September
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Eriks Kupce
    Organizer: Department of Molecular Chemistry and Materials Science

    Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM

    Date:
    05
    Thursday
    September
    2019
    Lecture / Seminar
    Time: 10:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM
    Organizer: Department of Chemical Research Support

    Enhanced single-molecule imaging through mechanistic analysis of blinking and point-spread function engineering?

    Date:
    09
    Tuesday
    July
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Prof. Peter Dedecker
    Organizer: Department of Chemical and Structural Biology

    Measuring nanometre distances in biomolecules using EPR Spectroscopy

    Date:
    27
    Thursday
    June
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Janet Lovett
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: EPR spectroscopy can be used to measure nanometre-scale distances within biomole ... Read more EPR spectroscopy can be used to measure nanometre-scale distances within biomolecules and other soft matter, through determining the dipolar coupling between paramagnetic centres. These can be placed site-specifically within the molecules-of-interest as spin labels. Some experiments that measure the dipolar coupling will be introduced, and results including new spin labels and applications of the methodology will be discussed.
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    Methods and Problems in BioImaging Workshop

    Date:
    24
    Monday
    June
    2019
    Conference
    Time: 08:00-18:00
    Location: David Lopatie Conference Centre

    Single and multi-frequency saturation methods for molecular and microstructural contrast in human MRI”

    Date:
    20
    Thursday
    June
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Elena Vinogradov
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Magnetic Resonance Imaging (MRI) provides excellent quality images of soft tissu ... Read more Magnetic Resonance Imaging (MRI) provides excellent quality images of soft tissues and is an established modality for diagnosis, prognosis and monitoring of various diseases. Majority of MRI scans in clinical practice today report on anatomy, morphology and sometimes physiology. The new area of active studies is aimed at developing MRI contrast methods for the detection of the events at the microstructural and molecular level employing endogenous properties. Here, we will discuss methods that employ single- and multi-frequency saturation to detect events on microstructural and molecular level. First, we will describe principles and translational aspects of Chemical Exchange Saturation Transfer1(CEST). CEST employs selective saturation of the exchanging protons and subsequent detection of the water signal decrease to create images that are weighted by the presence of a metabolite or pH2. We will describe aspects of translating CEST to reliable clinical applications and discuss its potential uses in human oncology, specifically breast cancer. Second, we will describe a method called inhomogeneous Magnetization Transfer3 (ihMT), which employs dual-frequency saturation to create contrast originating from the residual dipolar couplings and thus specific to microstructure. We will focus on the application of ihMT to the detection of myelin in brain and spinal cord. Finally, we will discuss a novel exchange-sensitive method based on the balanced steady-state free precession (bSSFP) sequence as an alternative way for chemical exchange detection (bSSFPX4). Using an effective field description, similarities between bSSFP and CW application can be explored and utilized for in-vivo MRI contrast. [1] K. Ward, et.al., JMR,143,79-87 (2000). [2] J. Zhou, et.al., Nature Medicine, 9,1085-1090 (2003). [3] G. Varma, et.al., MRM, 73, 614-622 (2015). [4] S. Zhang, et.al., JMR, 275, 55-67 (2017).
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    Brain control and readout at biologically relevant resolutions

    Date:
    17
    Monday
    June
    2019
    Lecture / Seminar
    Time: 11:00
    Location: Max and Lillian Candiotty Building
    Lecturer: Dr. Or Shemesh
    Organizer: Department of Brain Sciences
    Details: Host: Prof. Rony Paz rony.paz@weizmann.ac.il tel: 6236 For assistance with acc ... Read more Host: Prof. Rony Paz rony.paz@weizmann.ac.il tel: 6236 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: Understanding the neural basis of behavior requires studying the activity of neu ... Read more Understanding the neural basis of behavior requires studying the activity of neural networks. Within a neural network, single neurons can have different firing properties, different neural codes and different synaptic counterparts. Therefore, it will be useful to readout from the brain and control it at a single-cell resolution. However, until recently, single cell readout and control in the brain were not feasible. The first scientific problem we addressed, is this regard, was the low spatial resolution of light based neural activation. Opsins are genetically encoded light switches for neurons that cause neural firing, or inhibition, when illuminated (and are therefore called “opto-genetic” molecules). However, optogenetic experiments are biased by ‘crosstalk’: the accidental stimulation of dozens of cells other than the cell of interest during neuron photostimulation. This is caused by expression of optogenetic molecules through the entirety of the cells, from the round cell body (“soma”) to the elongated neural processes. Our solution was molecular-focusing: by limiting the powerful opsin CoChR to the cell body of the neuron, we discovered that we could excite the cell body of interest alone. This molecule, termed “somatic-CoChR” was stimulated with state of the art holographic stimulation to enable millisecond temporal control which can emulate actual brain activity. Thus, we achieved for the first time single cell optogenteic stimulation at sub millisecond temporal precision. A second challenge was imaging the activity of multiple cells at a single cell resolution. The most popular neural activity indicator is the genetically encoded calcium sensor GCaMP, due to its optical brightness and high sensitivity. However, the fluorescent signal originating from a cell body is contaminated with multiple other fluorescent signals that originate from neurites of neighboring cells. This leads to a variety of artifacts including non-physiological correlation between cells and an impaired ability to distinguish between signals coming from different cells. To solve this, we made a cell body-targeted GCaMP. We screened over 30 different targeting motifs for somatic localization of GCaMP, and termed the best one, in terms of somatic localization, “SomaGCaMP”. This molecule was tested in live mice and zebrafish and can report the activity of thousands of neurons at a single cell resolution. A third challenge was voltage imaging in the brain, since genetically encoded indicators still suffered from either low sensitivity, or from low brightness. To record voltage, we used nitrogen vacancy nanodiamonds, known to be both very bright and sensitive to electric fields. Our aim was to bring the nanodiamonds to the membrane so the large electric field created by the action potential could impinge upon them and change their fluorescence. By making the nanodiamonds hydrophobic through surface chemistry modification, and inserting them into micelles, we labeled neural membranes with monodisperse diamonds for hours. We are now in the process of assessing the sensitivity of the nanodiamonds to the membrane voltage. Altogether, thinking backwards from fundamental limitations in neuroscience is instrumental in deriving strategies to fix these limitations and study the brain. In the future, we will use similar approaches to study and heal brain disease, at single-cell and subcellular resolutions.
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    Design and validation of a head coil for MRI at 7T

    Date:
    12
    Wednesday
    June
    2019
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Shajan Gunamony
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Radio frequency (RF) coil design for ultra-high field MRI scanners is an active ... Read more Radio frequency (RF) coil design for ultra-high field MRI scanners is an active field of research. We have recently developed an 8-channel transmit, 32-channel receive 7T head coil at the University of Glasgow. We focused on an open-faced design to make the setup less claustrophobic and more acceptable in a clinical environment. Furthermore, the coil can be used in both the scanner modes. I will also present our internal validation process which allows home-built RF coils to be used in vivo.
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    Finding a Needle: Correlative Light and Volume EM Approach to Resolve Vesicular Fusion

    Date:
    28
    Tuesday
    May
    2019
    Lecture / Seminar
    Time: 10:15-10:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Nadav Scher
    Organizer: Department of Biomolecular Sciences
    Abstract: Most biological phenomena must be studied across scales, ranging from entire org ... Read more Most biological phenomena must be studied across scales, ranging from entire organisms to molecules in cells. However, bridging these scales can often be challenging, especially if dynamic changes in protein composition must be examined together with changes in cellular organization and ultrastructure. To overcome these challenges, we are developing an imaging approach harnessing the strengths of fluorescence microscopy and large volume electron microscopy, which can be achieved with a focused ion beam scanning electron microscope (FIB/SEM). In my talk, I will present the state-of-the-art in our correlative light and volume electron microscopy workflow and demonstrate its application for the study of secretion in the fruit fly’s salivary gland.
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    Revealing the dynamic stability of fusion pores in giant vesicles through live, super-resolution microscopy

    Date:
    28
    Tuesday
    May
    2019
    Lecture / Seminar
    Time: 10:00-10:15
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Tom Biton
    Organizer: Department of Biomolecular Sciences
    Abstract: Exocytosis occurs in all living cells and is essential for many cellular process ... Read more Exocytosis occurs in all living cells and is essential for many cellular processes including metabolism, signaling, and trafficking. During exocytosis, cargo loaded vesicles dock and fuse with the plasma membrane to release their content. To accommodate different cargos and cellular needs exocytosis must occur across scales; From synaptic vesicles that are only ~50nm in diameter, and neuroendocrine vesicles that are in the ~500nm range to giant secretory vesicles filled with viscous cargo, such as in the acinar cells in the exocrine pancreas, that reach up to a few µm in diameter. Yet, how fusion and content release are adapted to remain function across these scales is not well understood. It is well established that during exocytosis of small vesicles, vesicle fusion can proceed through one of two pathways: The first is complete incorporation, when the vesicular membrane fuses to the target membrane and the fusion pore expand irreversibly, incorporating the vesicular membrane into the target membrane. The second is “kiss-and-run”, when the fusion pore flickers, opening briefly and collapsing rapidly into two separate membranes. I am interested in understanding how exocytosis occurs in giant vesicles witch challenge efficient secretion and membrane homeostasis due to their massive size and viscous content. I am using the salivary gland of D. Melanogaster, as a model system for giant vesicles secretion. The vesicles in the gland measure between 5-8 µm, fuse and secrete viscous content into a preformed lumen. To visualize the secretion process, I adapted a method for super-resolution microscopy to live-gland imaging. I observed that fusion pores of giant vesicles expand to a stable opening of up to 3µm and slowly constricts down to hundreds of nm or less during secretion. Because constricting a membrane pore from “infinity” in molecular terms, back to a very narrow ‘stalk’ demands an investment of energy, I hypothesized that this is mediated by a specialized protein machinery. I am currently screening for the components of the machinery using the enormous power of Drosophila genetics by taking a candidate gene approach. My preliminary results identify the BAR domain containing protein, MIM (missing in metastasis) as a key regulator of pore dynamics, leading to new and exciting insights into the molecular mechanism of cellular secretion and membrane homeostasis in live tissues.
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    Life Science Lectures - Emerging imaging technologies to study cell architecture, dynamics and function

    Date:
    27
    Monday
    May
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Jennifer Lippincott-Schwartz
    Organizer: Life Sciences
    Details: Host : Prof. Zvulun Elazar Light refreshments will be served at 13:40 in the lobby

    Departmental Seminar

    Date:
    26
    Sunday
    May
    2019
    Lecture / Seminar
    Time: 13:00-14:00
    Title: Developing a highly sensitive CRISPR based platform for virus and host functional genomics
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Yaara Finkel
    Organizer: Department of Molecular Genetics

    Imaging the human brain: ultra-high field MRI and new biomarkers

    Date:
    26
    Sunday
    May
    2019
    Lecture / Seminar
    Time: 13:00
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Rita Schmidt
    Organizer: Department of Physics of Complex Systems
    Abstract: Times New Roman (Headings CS) ... Read more Times New Roman (Headings CS)
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    CRASH COURSE ON GENOMICS and BIOINFORMATICS OF CANCER

    Date:
    18
    Thursday
    April
    2019
    Lecture / Seminar
    Time: 11:45-14:00
    Location: Max and Lillian Candiotty Building
    Lecturer: Prof. Eytan Ruppin, Prof. Itay Tirosh
    Organizer: Department of Biomolecular Sciences

    The mechanics of malaria parasite invasion of the red cell (and beyond): seeking a balanced view of parasite-host contributions to entry

    Date:
    16
    Tuesday
    April
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Jacob Baum
    Organizer: Department of Biomolecular Sciences
    Abstract: Entry of the malaria parasite merozoite, the micron sized cell responsible for b ... Read more Entry of the malaria parasite merozoite, the micron sized cell responsible for blood-stage malaria infection, into the human red blood cell defines establishment of malaria disease. The process is rapid yet contains a great depth of cell biology, one eukaryotic cell actively penetrating the other. Entry has long been seen as a very parasite-centric process with the merozoite literally driving its way into a passive erythrocyte. This is in marked contrast to other pathogens that utilise host-cell phagocytosis to gain entry to human cells. Has this inbalanced view been over-stated in the case of the merozoite? Recent data from several groups suggests that erythrocyte biophysics (including membrane biophysical properties) also contributes to the process of merozoite entry. Here, I will present our latest insights into the role of both parasite and host cell factors and how they might be contributing to lowering the energy barrier required to get the merozoite inside the human red blood cell. With a particular focus on cell imaging, I will present our vision of invasion being a balanced equation with parasite motor force and host membrane deformability both contributing to allow the blood-stage malaria parasite (and may be beyond the blood stages) get in.
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    Advanced Electron Microscopy Symposium

    Date:
    10
    Wednesday
    April
    2019
    -
    11
    Thursday
    April
    2019
    Conference
    Time: 08:00
    Location: David Lopatie Conference Centre
    Organizer: Department of Chemical Research Support

    Growth mechanisms of quasi-1D semiconductors and oxides deduced from real-time electron microscopy

    Date:
    08
    Monday
    April
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Kolibal Miroslav
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: One-dimensional materials represent an attractive class of nanostructures, mainl ... Read more One-dimensional materials represent an attractive class of nanostructures, mainly because of their geometry which inherently implies applications such as electrodes for sensing purposes or conduction channels in nanoscale electronics. Different mechanisms may be utilized to prepare nanowires, e.g. stress-driven one-dimensional diffusion, metal-catalyzed growth (VLS) etc. The most important role in identifying and description of the growth mechanisms is played by real-time microscopies, mostly TEM. However, although very powerfull in terms of image resolution, TEM is also limited in use, especially because of very strict sample geometry requirements. In this seminar talk, I will present our real-time in-situ scanning electron microscopy experiments of nanowire growth. Two different material systems will be presented – germanium nanowires catalyzed by Au nanoparticles and WOx nanowires. As for the latter case, our experiments reveal a very unusual oxidation mechanism of tungsten disulfide nanotubes, resulting in tungsten oxide nanowire formation. The talk will summarize studies on quasi-1D systems conducted at IPE and CEITEC BUT.
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    Metal oxide growth within block copolymers – mechanism, challenges and opportunities

    Date:
    07
    Sunday
    April
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Tamar Segal-Peretz
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Self-assembly of block copolymers (BCP) is a well-known method for nanostructure ... Read more Self-assembly of block copolymers (BCP) is a well-known method for nanostructure fabrication at the 5-50 nm scale. Recently, sequential infiltration synthesis (SIS) was developed from atomic layer deposition (ALD) chemistry for selective growth of inorganic materials within polymers. In this talk, I will discuss SIS mechanism and growth process development as well as our work on combining BCP self-assembly with SIS for nanoparticle structuring, 3D imaging with TEM tomography, ultrafiltration membranes, and advanced 3D nanofabrication.
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    Optics in the Air

    Date:
    03
    Wednesday
    April
    2019
    Lecture / Seminar
    Time: 14:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Joseph Shaw
    Organizer: Department of Earth and Planetary Sciences
    Abstract: This talk will use photographs and diagrams to illustrate and explain some of th ... Read more This talk will use photographs and diagrams to illustrate and explain some of the beautiful optical phenomena observable in nature, such as ice‐crystal halos, rainbows, and sky colors, and will relate them to ongoing research into the spectral and spatial distribution of polarization in the atmosphere. Our group at Montana State University has pioneered all‐sky imaging methods to study skylight polarization and relate it to properties of airborne particles, clouds, and the underlying surface. Brief results from a deployment of all‐sky polarization imagers at the August 2017 solar eclipse will be shown and related to a more general discussion of atmospheric optical effects that can be seen by eye. The talk takes its title from my 2017 book, which describes optical phenomena in nature, especially as seen through airplane windows.
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    Imaging phase transitions with scanning SQUID

    Date:
    01
    Monday
    April
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Beena Kalisky
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: We use a local magnetic imaging technique, scanning SQUID microscopy, to map t ... Read more We use a local magnetic imaging technique, scanning SQUID microscopy, to map the spatial distribution of electronic states near surfaces and interfaces. We track conductivity, superconductivity and magnetism in systems undergoing phase transitions, where the local picture is particularly meaningful. I will describe two measurements: At the superconductor-insulator transition in NbTiN we map superconducting fluctuations and detect a non-trivial behavior near the quantum critical point. Near the metal to insulator transition at the 2D LaAlO3/SrTiO3 interface, we find that the conduction landscape changes dramatically and identify the way different types of defects control the behavior.
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    Molecules in Large and Small Pores as Observed by NMR Spectroscopy. Pore Structure, Tortuosity and Molecular Interactions

    Date:
    31
    Sunday
    March
    2019
    Lecture / Seminar
    Time: 15:30-16:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Istvan Furo
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: The seminar summarizes three recent studies (1,2,3) since that share some comm ... Read more The seminar summarizes three recent studies (1,2,3) since that share some common elements: they concern porous materials and the method used is NMR spectroscopy. Yet, the aims differ. In the first study (1), the unknown is the pore structure. In particular, pore structure in hydrogels is difficult to access as water cannot be removed without affecting the pores and in the presence of water the well-honed gas sorption and mercury porosimetries just do not work. The method we invented to remedy this situation is called size-exclusion quantification (SEQ) NMR and it can be seen as the multiplexed analogue of inverse size exclusion chromatography. In effect, we sample by diffusion NMR the size distribution in a polydisperse polymer solution before and after it had been equilibrated with a porous matrix. Size-dependent polymer ingress reveals the pore structure. The method has several advantages over possible alternatives, not least its speed. In the second study (2), we sample the self-diffusion of neat water and other molecules like dimethyl sulfoxide (DMSO) and their mixtures by NMR diffusion experiments for those fluids imbibed into controlled pore glasses (CPG, pore size range 7.5 to 73 nm). Their highly interconnected structure is scaled by pore size and exhibits pore topology independent of size. Relative to the respective diffusion coefficients obtained in bulk phases, we observe a reduction in the diffusion coefficient that is independent of pore size for the larger pores and becomes stronger toward the smaller pores. Geometric tortuosity governs the behavior at larger pore sizes, while the interaction with pore walls becomes the dominant factor toward smaller pore diameters. Deviation from the trends predicted by the popular Renkin equation and variants (4) indicates that the interaction with the pore wall is not just a simple steric one. In the third study (3), the porous material is hydrated cellulose. In that matrix, we identify by using 2H MAS NMR two different groups of water molecules being in slow exchange with each other. Water molecules in one of the groups exhibit anisotropic molecular motions with a high order parameter. Based on, among other things, the observed behavior with increasing vapor pressure, we argue that this water is an integral structural element of the cellulose fibril, that itself is an aggregate of the basic units, the cellulose nanofibrils.
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    The Lab on a Beam: From Learning Physics to Atomic Manipulation in Scanning Transmission Electron Microscopy

    Date:
    13
    Wednesday
    March
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Sergei Kalinin
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Atomically-resolved imaging of materials has become the mainstay of modern mater ... Read more Atomically-resolved imaging of materials has become the mainstay of modern materials science, as enabled by advent of aberration corrected scanning transmission electron microscopy (STEM). However, the wealth of quantitative information contained in the fine details of atomic structure or spectra remains largely unexplored. In this talk, I will present the new opportunities enabled by physics-informed big data and machine learning technologies to extract physical information from static and dynamic STEM images. The deep learning models trained on theoretically simulated images or labeled library data demonstrate extremely high efficiency in extracting atomic coordinates and trajectories, converting massive volumes of statistical and dynamic data into structural descriptors. I further present a method to take advantage of atomic-scale observations of chemical and structural fluctuations and use them to build a generative model (including near-neighbor interactions) that can be used to predict the phase diagram of the system in a finite temperature and composition space. Similar approach is applied to probe the kinetics of solid-state reactions on a single defect level and defect formation in solids via atomic-scale observations. Finally, synergy of deep learning image analytics and real-time feedback further allows harnessing beam-induced atomic and bond dynamics to enable direct atom-by-atom fabrication. Examples of direct atomic motion over mesoscopic distances, engineered doping at selected lattice site, and assembly of multiatomic structures will be demonstrated. These advances position STEM towards transition from purely imaging tool for atomic-scale laboratory of electronic, phonon, and quantum phenomena in atomically-engineered structures.
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    Spectral editing techniques for chemical exchange saturation transfer imaging

    Date:
    12
    Tuesday
    March
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Jiadi Xu
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI tec ... Read more Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through water. CEST MRI is still under development and one major impediment for more widespread application is limited specificity due to spectral overlap of CEST signal from other metabolites and proteins. In this presentation, I will demonstrate several novel CEST spectral editing techniques developed by our group to extract information from CEST images, such as one variable delay multi pulse (VDMP) CEST that acts an exchange rate filter to separate CEST effects from the confounding factors, one ultra-short echo (UTE)-CEST method that can monitor in vivo protein aggregation process and one polynomial and Lorentzian line-shape fitting (PLOF) CEST that can detect creatine and phosphocreatine in tissue with high specialty. Their applications on the stroke and Alzheimer’s disease models will be covered. At last, I will explore one artificial neural network approach to overcome the challenges of implementing the CEST technique on 3T clinical MRI scanners.
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    Pulsed Dipolar EPR Spectroscopy: From Model Systems to In-Cell

    Date:
    07
    Thursday
    March
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Olav Schiemann
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Understanding the function of biomolecules on a molecular level requires knowled ... Read more Understanding the function of biomolecules on a molecular level requires knowledge about their structure and conformational changes during function. Site directed spin labeling (SDSL) in combination with pulsed dipolar EPR spectroscopy (PDS) enables to gather such information on the nanometer length scale. In the talk, it will be shown that this approach enables the localization of metal ions within the fold of biomolecules, also of those metal ions with large zero-field splitting, where the high-field approximation breaks down. It will also be shown that this cannot only be done in vitro but also within cells. Last but not least, an example will be given where a conformational change of a protein is not only followed on the length- but also on the microsecond time resolution using PDS/SDSL.
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    Mn(II) EPR tracks the hydrolysis state and ATP/ADP dependent conformation in yeast Hsp90 chaperone

    Date:
    28
    Thursday
    February
    2019
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Angeliki Giannoulis
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Hsp90 plays a central role in cell homeostasis by assisting folding and maturati ... Read more Hsp90 plays a central role in cell homeostasis by assisting folding and maturation of many client proteins. In order to perform this chaperoning activity Hsp90 hydrolyzes ATP, which requires Mg(II) as cofactor and the hydrolysis is coupled to large global conformational changes. Hsp90 is homo-dimeric with each monomer consisting of three consecutive domains (CTD, MD, NTD). The ATPase site is found in each of the two NTDs, while the CTDs constitute the dimerization site. X-ray crystallography and FRET have provided insights on the conformational cycle of Hsp90 which involves transition from a nucleotide-free ‘open’ to a nucleotide-bound ‘closed’ conformation by dimerization of the NTDs. However, there are still open questions on whether the chaperone shifts global conformation as a consequence of hydrolysis. Here, we investigate the ATPase site and the concomitant conformational changes at various nucleotide-bound states (pre-hydrolysis, intermediate high energy and post- hydrolysis states) in yeast Hsp90 using EPR techniques. To do so, we substituted the Mg(II) cofactor with paramagnetic Mn(II) and performed hyperfine and pulsed dipolar EPR experiments, to probe short and long range interactions, respectively. Specifically, we tracked ATP hydrolysis by exploring the Mn(II) coordination by the nucleotide phosphates using 31P electron nuclear double resonance (ENDOR) spectroscopy. The interaction of the Mn(II) with protein residues in the different hydrolysis states was investigated by 14/15N ELDOR-detected nuclear magnetic resonance (EDNMR). Last, we measured the distance between the two Mn(II) cofactors in each of the monomers using double electron–electron resonance (DEER/PELDOR) spectroscopy. Here, we measured a well-defined Mn(II)-Mn(II) distance of 4.3 nm in the pre-hydrolysis state, which changes both in width and mean distance in the post-hydrolysis state providing experimental evidence to the existence of two different ‘closed’ conformations for the ATP and ADP bound states. Within our approach one can probe both local and global interactions from a single sample via exploitation of intrinsic sites (here Mg(II)->Mn(II)) that can potentially yield new structural insights previously challenging to observe with FRET and EPR using site-specific spin labeling.
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    "DLTS defects characterization of process and irradiation induced defects in 4H-SiC”

    Date:
    28
    Thursday
    February
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Mmantsae Diale
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: 4H-SiC epitaxial layers were irradiated using various radioactive sources and pa ... Read more 4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.
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    DLTS defects characterization of process and irradiation induced defects in 4H-SiC

    Date:
    28
    Thursday
    February
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Mmantsae Diale
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: 4H-SiC epitaxial layers were irradiated using various radioactive sources and pa ... Read more 4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.
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    Diamond quantum technologies: magnetic sensing, hyperpolarization and noise spectroscopy

    Date:
    27
    Wednesday
    February
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Nir Bar-Gill
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as ... Read more Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as well-controlled quantum systems, with promising applications ranging from quantum information science to magnetic sensing. In this talk, I will first introduce the NV center system and the experimental methods used for measuring them and controlling their quantum spin dynamics. I will mention the application of magnetic sensing using NVs through the realization of a magnetic microscope [1]. I will then describe our work on nuclear hyperpolarization, potentially relevant for enhanced MRI contrast, and research into open quantum systems and quantum thermodynamics [2]. Finally, I will present related control sequences, which can be used to perform optimized quantum noise spectroscopy, allowing for precise characterization of the environment surrounding a quantum sensor [3]. 1. E. FARCHI ET. AL., SPIN 7, 1740015 (2017). 2. HOVAV, Y., NAYDENOV, B., JELEZKO, F. AND BAR-GILL, N., PHYS. REV. LETT. 120, 6, 060405 (2018) 3. Y. ROMACH ET. AL., PHYS. REV. APPLIED 11, 014064 (2019).
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    Chemical and Biological Physics and Organic Chemistry Seminar

    Date:
    26
    Tuesday
    February
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Title: The Dynamics of Charged Excitons in Electronically and Morphologically Homogeneous Single-Walled Carbon Nanotubes
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Prof Michael J. Therien
    Organizer: Department of Chemical and Biological Physics
    Abstract: The trion, a three-body charge-exciton bound state, offers unique opportunities ... Read more The trion, a three-body charge-exciton bound state, offers unique opportunities to simultaneously manipulate charge, spin and excitation in one-dimensional single-walled carbon nanotubes (SWNTs) at room temperature. Effective exploitation of trion quasiparticles requires fundamental insight into their creation and decay dynamics. Such knowledge, however, remains elusive for SWNT trion states, due to the electronic and morphological heterogeneity of commonly interrogated SWNT samples, and the fact that transient spectroscopic signals uniquely associated with the trion state have not been identified. Here length-sorted SWNTs and precisely controlled charge carrier-doping densities are used to determine trion dynamics using femtosecond pump-probe spectroscopy. Identification of the trion transient absorptive hallmark enables us to demonstrate that trions (i) derive from a precursor excitonic state, (ii) are produced via migration of excitons to stationary hole-polaron sites, and (iii) decay in a first-order manner. Importantly, under appropriate carrier-doping densities, exciton-to-trion conversion in SWNTs can approach 100% at ambient temperature. We further show that ultrafast pump-probe spectroscopy, coupled with these fundamental insights into trion formation and decay dynamics, enables a straightforward approach for quantitatively evaluating the extent of optically-driven free carrier generation (FCG) in SWNTs: this work provides fundamental new insights into how quantum yields for optically-driven FCG [Φ(Enn → h+ + e−)] in SWNTs may be modulated as functions of the optical excitation energy and medium dielectric strength. Collectively, these findings open up new possibilities for exploiting trions in SWNT optoelectronics, ranging from photovoltaics, photodetectors, to spintronics.
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    Chemical and Biological Physics Guest Seminar

    Date:
    14
    Thursday
    February
    2019
    Lecture / Seminar
    Time: 11:00
    Title: A surface science approach to molecular and atomic contacts
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Dr. Richard Berndt
    Organizer: Department of Chemical and Biological Physics
    Abstract: Using low-temperature scanning tunneling microscopy we investigate molecular and ... Read more Using low-temperature scanning tunneling microscopy we investigate molecular and atomic structures at single crystal surfaces to explore their electron transport properties from the tunnelling range to ballistic transport. The experiments aim at maximizing the control over the junction properties and probe conductances, forces, shot-noise, and the emission of photons. We are particularly interested in molecules that exhibit switching behaviour of, e.g., their conformations or spin states. Results from metallic and molecular junctions will be presented.
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    Towards plug and play parallel transmission for 7T human brain MRI with universal pulses

    Date:
    07
    Thursday
    February
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Nicolas Boulant
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Parallel transmission has been the most promising approach to counteract the rad ... Read more Parallel transmission has been the most promising approach to counteract the radiofrequency (RF) field inhomogeneity problem in MRI at ultra-high field. Despite tremendous progress made by the community for more than a decade, the technology yet has failed to be embraced in routine practice because of a more complex safety management and a cumbersome calibration procedure for each subject in the scanner. After thorough tests and validations to address the former point, universal pulses were proposed a couple of years ago to circumvent the workflow problem in head imaging at 7T. For a given RF coil, they consist of designing, offline, pulse solutions to mitigate the RF field inhomogeneity problem while being robust to intersubject variability, all within explicit hardware and safety constraints. This talk will present the latest sequence and pulse developments incorporating these solutions, now covering 3D (GRE, MPRAGE, TSE, MP-FLAIR, DIR, 3D-EPI) and 2D (GRE, MB-EPI) sequences with first routine results for fMRI (resting-state HCP-style, localizer paradigm) and ongoing clinical studies (Multiple Sclerosis), thereby making parallel transmission one step closer to clinical routine and at zero cost for the user. Perhaps interestingly, to reach the desired versatility and simplicity, some solutions were inspired from solid-state NMR methods. To date the proposed universal pulses cumulate tests on around 50 volunteers and across 4 sites. They have never failed to return brain images virtually free of B1+ artefacts at 7T.
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    Extension of in-situ nanoindentation results by (S)TEM graphical data processing

    Date:
    06
    Wednesday
    February
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Vasily A. Lebedev
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Nanomechanical measurements allow us to determine mechanical characteristics o ... Read more Nanomechanical measurements allow us to determine mechanical characteristics of nano- and microobjects, which is required for further calculations of the mechanical parameters of the structures based on them. At the same time, in-situ measurements are carried out in the SEM and TEM chambers. Thus, it is possible to acquire graphic information that can supplement the indentation data. In this work, indentation of titania microspheres with different phase composition was tested by MEMS-based Hysitron PI-95 at Zeiss Libra 200MC TEM. Evaluation of the mechanical properties of microspheres in the elastic region was made according to the Hertz model. It turned out that annealing of the amorphous titania leads to an increase in the Young modulus, whereas the hydrothermal treatment reduces it from 27 to 4 Gpa. The differences in the destruction process was demonstrated for these kinds of particles. It has been shown, that hydrothermal treatment of titania microspheres leads to the formation of a reticular internal structure, whereas annealing results in sintering of the internal structure of microspheres. In the process of indentation, corresponding videos were also recorded, including the probe approach, indentation, and destruction of the microspheres. In order to process the videos we coded the program based on free Python packages. Using the Digital Image Correlation (DIC) algorithm, relative probe displacements were measured during indentation (Fig. 1a). The results obtained allowed us to clarify the calibration of the movement of the indenter in free sample tests, as well as to determine the drift function in real measurements. These results are important for long-term measurements, in particular creep tests. Based on graphical data we were able to determine the evolution of the shape of indented microspheres. During the video processing, areas of individual objects were determined, sizes of contact areas were calculated, and changes in linear dimensions of the deformed objects were determined (Fig. 1b). Therefore, a large amount of quantitative data was obtained from electron microscopy images. Fig.1 Illustration of probe displacement determination (a) and the shape evolution analysis
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    Time-resolved neural activity and plasticity in behaving rodents using high field MRI

    Date:
    05
    Tuesday
    February
    2019
    Lecture / Seminar
    Time: 14:00
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Noam Shemesh
    Organizer: Department of Brain Sciences
    Details: Light refreshments before the seminar Host: Prof. Elad Schneidman elad.schneidm ... Read more Light refreshments before the seminar Host: Prof. Elad Schneidman elad.schneidman@weizmann.ac.il tel: 2239 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Microstructural MRI: beyond the Standard Model

    Date:
    03
    Sunday
    February
    2019
    Lecture / Seminar
    Time: 16:30-17:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Noam Shemesh
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Despite the importance of tissue microstructure in health and disease, its nonin ... Read more Despite the importance of tissue microstructure in health and disease, its noninvasive characterization remains a formidable challenge. Signal representations (diffusion/kurtosis tensors) are unspecific while tissue modelling using ideal geometries representing different cellular components have failed when scrutinized vis-à-vis histology: axon diameter, for example, is overestimated by factors of >6. Biophysical models characterizing signal behavior in specific diffusion-weighting regimes (power law scaling in “q” or “t”) have been more recently proposed as more reliable means for characterizing tissues. In recent years, the most prevalent biophysical model for diffusion in tissues was termed the “Standard Model”, consisting of a sum of gaussian components (nearly always two), one of which with zero diffusivity (stick). In the lecture, we will present validity regimes for the standard model and provide evidence for its limits. We will then propose a few novel means for characterizing
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    Neuromodulation of dendritic excitability

    Date:
    29
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 14:00
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Mickey London
    Organizer: Department of Brain Sciences
    Details: Host: Dr.Ivo Spiegel ivo.spiegel@weizmann.ac.il tel: 4415 For assistance with ... Read more Host: Dr.Ivo Spiegel ivo.spiegel@weizmann.ac.il tel: 4415 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: The excitability of the apical tuft of layer 5 pyramidal neurons is thought to p ... Read more The excitability of the apical tuft of layer 5 pyramidal neurons is thought to play a crucial role in behavioral performance and synaptic plasticity. We show that the excitability of the apical tuft is sensitive to adrenergic neuromodulation. Using two-photon dendritic Ca2+ imaging and in vivo whole-cell and extracellular recordings in awake mice, we show that application of the a2A-adrenoceptor agonist guanfacine increases the probability of dendritic Ca2+ events in the tuft and lowers the threshold for dendritic Ca2+ spikes. We further show that these effects are likely to be mediated by the dendritic current Ih. Modulation of Ih in a realistic compartmental model controlled both the generation and magnitude of dendritic calcium spikes in the apical tuft. These findings suggest that adrenergic neuromodulation may affect cognitive processes such as sensory integration, attention, and working memory by regulating the sensitivity of layer 5 pyramidal neurons to top-down inputs.
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    Understanding properties of advanced low-dimensional materials by low-voltage atomic-scale TEM experiments

    Date:
    22
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Ute Kaiser
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: A new type of transmission electron microscopes operating at electron energies b ... Read more A new type of transmission electron microscopes operating at electron energies between 80keV and 20keV has been developed to obtain structural and electronic properties of advanced low-dimensional material at the atomic scale. It allows to undercut most of the materials knock-on damage thresholds and enables sub-Angstroem resolution in an 4000x4000 pixels, single-shoot image down to 40keV by correcting not only the geometrical aberrations of the objective lens but also its chromatic aberration. During the imaging process, the interaction of the beam electrons with the low-dimensional material can, nevertheless, results in changes of the atomic structure due to ionization and radiolysis, and sophisticated sample preparation methods are employed to reduce these effects. In this talk, we briefly outline key instrumental and methodological developments and report on structural properties of low-dimensional materials. We not only determine the structure of the pristine material but also use the electron beam to engineer defined properties. Thus, we show for instance the dynamics of extended defects in MoTe2 and WS2 and the creation of a commensurate charge density wave (CDW) in a monolayer 1T-TaSe2, as well as properties of MnPS3, and moreover the dynamics and bond order changing of dirhenium molecule in single-walled carbon nanotubes. Finally we intercalate bilayer graphene by lithium and study in-situ lithiation and delithiation between bilayer graphene, identify single Li atoms as well as the structure of the new high density crystalline Li- phase.
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    Proteins on membrane interfaces: Structure and dynamics of lipid-protein fibers from advanced fluorescence spectroscopy and microscopy methodologies

    Date:
    22
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Prof. Manuel Prieto
    Organizer: Department of Chemical and Structural Biology

    Connecting the dots: functional and structural insights into the Legionella pneumophila Dot/Icm secretion system

    Date:
    22
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. David Chetrit
    Organizer: Department of Biomolecular Sciences
    Abstract: Type IV secretion systems (T4SS) are widespread in bacteria and despite their fu ... Read more Type IV secretion systems (T4SS) are widespread in bacteria and despite their fundamental importance in processes such as DNA conjugation and pathogenesis of plants, animals and humans, they are among the most complex and yet arguably the least understood secretion systems in the prokaryotic kingdom. Using live fluorescence microscopy in conjunction with cryo-electron tomography, we determined the in-situ structure of the T4SS of the respiratory pathogen Legionella pneumophila, called Dot/Icm. Unexpectedly, we have discovered that the major ATPases energizing center in the cytosol of the bacterial cell creates a dynamic assembly and forms a unique central channel in that it is constructed by a hexameric array of dimeric proteins. We have showed that the ATPase DotB cycles between the cytosol and the Type IV machine, indicating that it is involved in energizing the Type IV apparatus once a signal is received to initiate protein translocation. Our data changed the existing paradigm for how T4SS function and provides new insights for future studies that are important for a complete understanding of host pathogen interaction processes.
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    Imaging Topological Materials

    Date:
    17
    Thursday
    January
    2019
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Jenny Hoffman
    Organizer: Faculty of Physics
    Details: 11:00 – coffee, tea, and more
    Abstract: Today’s electronic technology – the pixels on the screen and the process to ... Read more Today’s electronic technology – the pixels on the screen and the process to print the words on the page – are all made possible by the controlled motion of an electron’s charge. In the last decade, the discovery of topological band insulators with robust spin-polarized surface states has launched a new subfield of physics promising a new paradigm in computing. When topology is combined with strong electron correlations, even more interesting states of matter can arise, suggesting additional applications in quantum computing. Here we present the first direct proof of a strongly correlated topological insulator. Using scanning tunneling microscopy to probe the real and momentum space structure of SmB6, we quantify the opening of a Kondo insulating gap. Within that gap, we discover linearly dispersing surface states with the heaviest observed Dirac states in any material – hundreds of times the mass of a free electron. We show how single atom defects can scatter these surface states, which paves the way towards manipulating single atoms and thus controlling surface states and their excitations at the nanoscale.
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    Special Guest Seminar with Ariel Schwartz

    Date:
    17
    Thursday
    January
    2019
    Lecture / Seminar
    Time: 10:00
    Title: “Deep Semantic Genome and Protein Representation for Annotation, Discovery, and Engineering”
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Ariel Schwartz
    Organizer: Department of Molecular Genetics
    Abstract: Computational assignment of function to proteins with no known homologs is still ... Read more Computational assignment of function to proteins with no known homologs is still an unsolved problem. We have created a novel, function-based approach to protein annotation and discovery called D-SPACE (Deep Semantic Protein Annotation Classification and Exploration), comprised of a multi-task, multi-label deep neural network trained on over 70 million proteins. Distinct from homology and motif-based methods, D-SPACE encodes proteins in high-dimensional representations (embeddings), allowing the accurate assignment of over 180,000 labels for 13 distinct tasks. The embedding representation enables fast searches for functionally related proteins, including homologs undetectable by traditional approaches. D-SPACE annotates all 109 million proteins in UniProt in under 35 hours on a single computer and searches the entirety of these in seconds. D-SPACE further quantifies the relative functional effect of mutations, facilitating rapid in-silico mutagenesis for protein engineering applications. D-SPACE incorporates protein annotation, search, and other exploratory efforts into a single cohesive model. We have recently extended this work from protein to DNA, enabling assignment of function to whole genomes and metagenomic contigs in seconds. Conserved genomic motifs as well as the functional impact of mutations in coding as well as non-coding genomic regions can be predicted directly from raw DNA sequence without the use of traditional comparative genomics approaches for motif detection, such as multiple sequence alignments, PSSMs, and profile HMMs.
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    Using solution NMR spectroscopy to characterise the dynamics of side chains and ions in proteins

    Date:
    17
    Thursday
    January
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Flemming Hansen
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Proteins are dynamic entities and function is often related to motions on time-s ... Read more Proteins are dynamic entities and function is often related to motions on time-scales from picoseconds to seconds. Understanding not only the backbone, but also the dynamics and interactions of side chains and ions within proteins is crucial, because side chains cover protein surfaces and are imperative for substrate recognition and both side chains and ions are key for most active sites in enzymes. New NMR-based methods, anchored in 13C-direct-detection, to characterise the motions and interactions of functional side chains in large proteins will be presented. One class of experiments is aimed at arginine side chains and allows the strength of interactions formed via the guanidinium group to be quantified. NMR measurements of the solvent exchange rate of labile guanidinium protons as well as measurements of the rotational motion about the Nε-Cζ bond allows for such quantifications. Secondly, a new class of NMR experiments is presented, which relies on 13C-13C correlation spectra and allows a general quantification of motion and structure of side chains in large proteins. The new 13C-13C correlation spectra are applied to a 82 kDa protein, where well-resolved spectra with minimal overlap are obtained within a few hours. NMR-based methods to characterise potassium binding in medium-large proteins will also be presented. Due to its size, 15N-ammonium can be used as a proxy for potassium to probe potassium binding in medium-large proteins. NMR pulse sequences will be presented to select specific spin density matrix elements of the 15NH4+ spin system and to measure their relaxation rates in order to characterise the rotational correlation time of protein-bound 15NH4+ as well as report on chemical exchange events of the 15NH4+ ion.
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    Chemical and Biological Physics and Organic Chemistry Seminar

    Date:
    15
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 11:00
    Title: The Renaissance of Sabatier CO2 Hydrogenation Catalysis
    Location: Perlman Chemical Sciences Building
    Lecturer: Charlotte Vogt‎
    Organizer: Department of Chemical and Biological Physics
    Abstract: The 100-year old Sabatier reaction, i.e. catalytic CO2 hydrogenation, is now see ... Read more The 100-year old Sabatier reaction, i.e. catalytic CO2 hydrogenation, is now seeing a renaissance due to its application in Power-to-Methane processes for electric grid stability and potential CO2 emission mitigation [1]. To date however, the fundamentals of this important catalytic reaction are still a matter of debate. This is partly due to the structure sensitive nature of CO2 hydrogenation: not all surface atoms of the active phase nanoparticles have the same specific activity. Recently, we have showed how the mechanism of catalytic CO2 methanation depends on Ni nanoparticle size using a unique set of well-defined silica-supported Ni nanoclusters (in the range 1-7 nm) and advanced characterization methods (i.e., operando FT-IR, and operando quick X-ray absorption spectroscopy) [2]. By utilizing fundamental theoretical concepts proving why CO2 is structure sensitive, and how CO2 is activated mechanistically and linking spectroscopic descriptors to these fundamental findings we ultimately leverage our understanding with a toolbox of structure sensitivity, and a library of reducible and non-reducible supports (SiO2, Al2O3, CeO2, ZrO2 and TiO2), tuning the selectivity and activity of methanation over Ni [3]. For example, we show that CO2 hydrogenation over Ni can and does form propane. This work contributes to our ability to produce “ideal” catalysts by improving the understanding of the catalytic sites and reaction pathways responsible for higher activity and even C-C coupling. This toolbox is thus not only useful for the highly active and selective production of methane within the Power-to-Methane concept, but also provides new insights for CO2 activation towards value-added chemicals thereby reducing the deleterious effects of this environmentally harmful molecule.
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    G-CLEF and the search for Biomarkers in Exoplanets Atmospheres

    Date:
    08
    Tuesday
    January
    2019
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Dr. Sagi Ben-Ami
    Organizer: Faculty of Physics
    Details: 11:00 Coffee, tea and more
    Abstract: Following a review of G-CLEF – a first light High-R spectrograph for the Giant ... Read more Following a review of G-CLEF – a first light High-R spectrograph for the Giant Magellan Telescope, I will present a concept extreme high resolution spectrograph optimized for molecular oxygen detection, a prominent biomarker in Earth atmosphere, using the transmission spectroscopy method. The instrument is based on the transmission properties of Fabry Perot Interferometers, and despite its modest dimensions is capable of achieving spectral resolution and sampling frequency in excess of R~300,000. I will discuss design parameters and the unique aspects that needs to be taken into account in the design of an FPI based instrument, and conclude with MC simulation results demonstrating the advantages of such a novel instrument.
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    Fluorescent Sensors and Imaging agents

    Date:
    08
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Helen and Milton A. Kimmelman Building
    Lecturer: Prof. Tony James
    Organizer: Department of Molecular Chemistry and Materials Science

    Ben May Theory and Computation Seminar

    Date:
    07
    Monday
    January
    2019
    Lecture / Seminar
    Time: 11:00
    Title: New Mathematics to Understand Life One Photon at a Time
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Steve Pressé
    Organizer: Department of Chemical and Biological Physics
    Abstract: Monitoring life in action—as it occurs in real time within the cellular cytopl ... Read more Monitoring life in action—as it occurs in real time within the cellular cytoplasm at the relevant single molecule scale—remains an important challenge. In order to see life unravel and monitor specific biomolecules as they diffuse and assemble in the cytoplasm, we create contrast with the cellular background by fluorescently labeling biomolecules. Yet the diffraction limit of light naively keeps us from peering into length scales comparable to those of single molecules. For this reason, the 2014 Chemistry Nobel Prize was awarded for separating signals from particles in time that cannot otherwise be separated in space to localize biomolecular structures to a precision beyond the diffraction limit. However, this process is slow and thus we compromise temporal resolution by separating signal in time. Here we present new Mathematics that make it possible to consider complex dynamical signals from which we can build a story of life in action starting from single, or very few, photons. The methods we present—motivated by the tools of Bayesian nonparametrics—show us how to achieve diffraction-limited tracking from signal previously considered insufficient. If time allows, we will discuss extensions of our methods to inferring diffusional dynamics from single photon arrivals from confocal imaging methods
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    Chemical and Biological Physics Guest Seminar

    Date:
    30
    Sunday
    December
    2018
    Lecture / Seminar
    Time: 09:30
    Title: New Frontiers in Membrane Biophysics
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Raya Sorkin
    Organizer: Department of Chemical and Biological Physics
    Abstract: Membranes compartmentalize living matter into cells and subcellular structures. ... Read more Membranes compartmentalize living matter into cells and subcellular structures. Many life processes involve membrane topological changes and remodelling: the uptake of materials via endocytosis and secretion by exocytosis, the generation of intra or extra-cellular vesicles as well as various membrane fusion processes. In order to get to the bottom of these fundamental physiological processes, it is vital to study membrane mechanical properties and membrane deformation. In this talk I will present the results of our research on several aspects of vesicle generation and membrane fusion using single molecule techniques. By means of an AFM force spectroscopy study we characterized the mechanical properties of small natural vesicles, called extracellular vesicles (EVs). Investigating the mechanical properties of these vesicles and their lipid and protein content provided new insights into the still poorly understood processes underlying vesicle generation. Acoustic Force Spectroscopy (AFS) was the choice for our novel methodology to measure cell mechanical properties. It enabled our finding that uptake of EVs by cells changes cellular deformability, a process that may have implications in several disease states where EV levels are significantly elevated, such as malaria and breast cancer. Combining optical tweezers with confocal fluorescence microscopy was the perfect tool for the investigation of membrane remodelling by calcium sensor proteins which are crucial in neuronal communication. We discovered surprising differences between the action mechanisms of two structurally similar proteins, Doc2b and Synaptotagmin-1 (Syt1), as determined by quantifying the strength and probabilities of protein-induced membrane-membrane interactions. Overall these fundamentally new insights into central biological processes were possible by our biophysical characterization of membranes using a powerful combination of single molecule techniques: Optical tweezers combined with confocal fluorescent microscopy, AFS and AFM.
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    Symmetry breaking in the synthesis of chiral nanocrystals

    Date:
    26
    Wednesday
    December
    2018
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Gil Markovich
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: In recent years we have been studying the handedness controlled synthesis of ino ... Read more In recent years we have been studying the handedness controlled synthesis of inorganic nanocrystals made of materials which crystallize in chiral space-groups. In the talk I will discuss the demonstration of strong chiral amplification in the colloidal synthesis of intrinsically chiral lanthanide phosphate nanocrystals, quantitatively measured via the circularly polarized luminescence of the lanthanide ions within the nanocrystals. Together with the group of Ori Cheshnovsky, we were able to measure single particle handedness though circularly polarized emission microscopy. We obtained 100% enantiomeric purity of the nanocrystals by using chiral tartaric acid molecules in the synthesis which act as an external “chiral field”, sensitively directing the amplified nanocrystal handedness through a discontinuous transition between left- and right-handed excess. The amplification involves also spontaneous symmetry breaking into either left- or right-handed nanocrystals below a critical temperature, in the absence of the tartaric acid molecules. These characteristics suggest a conceptual framework for chiral amplification, based on the statistical thermodynamics of critical phenomena, which we use (with Haim Diamant) to quantitatively account for the observations.
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    Paramagnetic tagging of proteins for structural biology applications

    Date:
    25
    Tuesday
    December
    2018
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Xun-Cheng Su
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Site-specific installation of paramagnetic lanthanide ions in proteins is a powe ... Read more Site-specific installation of paramagnetic lanthanide ions in proteins is a powerful method in delineating the structures, dynamics and interactions of proteins by NMR and EPR. Since most proteins do not have a paramagnetic center, efforts towards site-specific labeling of proteins with paramagnetic ions have thus been made via thiol chemistry, click chemistry, and molecular biology. The formation of disulfide bond between a protein and the paramagnetic tag is mostly applied in protein modifications, whereas the disulfide bond tether succumbs to low stability in reducing conditions or high pH. We have been focusing on development of paramagnetic tagging proteins in formation of a stable thioether bond for analysis of proteins in vitro and in cells using NMR and EPR. A number of stable paramagnetic tags have been designed and the performance of the respective protein conjugates has been evaluated in vitro and in cells by high resolution NMR spectroscopy. Using these high-performance paramagnetic tags, we were able to determine the 3D structure of a protein in live cells and 3D structure of unstable and short-lived thioester intermediate of Sortase A with pseudocontact shifts (PCSs) as structural restraints.
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    “Anharmonicity and Electron-Phonon Interaction in Dielectrically-Confined 2D Materials”

    Date:
    19
    Wednesday
    December
    2018
    Lecture / Seminar
    Time: 14:00-15:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Matan Menahem
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Electron-phonon interaction (EPI) is the influence of structural dynamics on cha ... Read more Electron-phonon interaction (EPI) is the influence of structural dynamics on charge-carrier’s band structure, by changes in the potential acting on a charge carrier due to atomic displacements. When the atomic displacements are anharmonic, and the quasi-harmonic approximation is no longer sufficient, the existing theory fails to explain or predict the macroscopic properties of the material. In quantum confined systems with dielectric mismatch between well and barrier, the effect of atomic displacements on the dielectric environment of charge carriers is greater due to dielectric confinement. 2D hybrid halide perovskites (HHPs) are easy to synthesize, easily tunable dielectric confined materials with pronounced optical response, even at room temperature. Recent studies show the effect of anharmonicity on the optical properties of 3D perovskites and strong EPI in 2D HHPs, affected by temperature. I aim to investigate the effect of anharmonicity on the dielectric environment of charge carriers in prototypical dielectric confined 2D HHPs, using various methods of optical spectroscopy. I hypothesize that anharmonicity would decrease the excitonic binding energy and electron-phonon scattering, due to more efficient charge screening and phonon-phonon scattering.
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    Halide Exchange in Single Crystal Halide Perovskites

    Date:
    17
    Monday
    December
    2018
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Aya Osherov
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Halide Perovskites (HaPs) have remarkable electronic and optical characteristics ... Read more Halide Perovskites (HaPs) have remarkable electronic and optical characteristics, but much is still unknown regarding the connection between their physical and chemical properties. Cation or anion substitution can change the optical absorption edge, with or without change of structure. In this work I explored the halide exchange reaction in methylammonium lead tri-halides single crystals (SCs) in order to understand the process of exchange and the stability of the product(s). I demonstrate halide exchange in mm-sized SCs, achieved by diffusion. Using the Boltzmann-Matano method and diffusion profiles obtained by electron dispersive spectroscopy it is possible to evaluate the halide diffusion coefficients, which are not constant and depend on the mixture of halides. For all permutations, the change in composition as result of the diffusion, strongly affects the optical and electrical properties and especially the band gap of the semiconducting crystals, as seen in cathodoluminescence measurements in the scanning electron microscope. While these gradients cause a lattice parameter change and may cause a symmetry change, X-ray diffraction measurements show that if the interchanged halide pair is such that their sizes are relatively similar (e.g., and , and but not and ) the resulting material remains surprisingly single crystalline. These findings are valid, no matter which one of the two halides is being exchanged. These results suggest that for these similar-sized halide pairs, this exchange occurs through a solid-state chemical reaction such that the resulting crystal orientation is determined by that of the initial crystal.
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    “Diffusion NMR of out-of-equilibrium mixtures”

    Date:
    11
    Tuesday
    December
    2018
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Jean-Nicolas Dumez
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: The NMR spectra of molecular species in solution mixtures can be separated with ... Read more The NMR spectra of molecular species in solution mixtures can be separated with diffusion-ordered NMR spectroscopy (DOSY), a ‘virtual chromatography’ approach based on the measurement of translational diffusion coefficients. Classic DOSY experiments, however, require several minutes are not applicable to many important time-evolving mixtures. Taking advantage of the concept of spatial encoding, we show here that DOSY data can be collected in a single scan of less than one second for several types of out-of-equilibrium mixtures. SPEN provides an acceleration of DOSY experiments by several orders of magnitude. SPEN DOSY pulse sequences are developed, that compensate for convection effects and are suitable for measurements in low-viscosity organic solvents, a requirement to monitor organic chemical reactions. We also show how to collect multiple consecutive scans from short-lived, non-renewable signals produced by dissolution dynamic nuclear polarisation (D-DNP), which is a versatile and powerful hyperpolarisation method. These methodological developments are supported by advanced numerical simulations, based on a Fokker-Plank formalism to describe simultaneously the spin and spatial dynamics. An exemple of hyperpolarised sample is given with a model mixture of small molecules, while the ability to monitor a reacting mixture is illustrated with a diamination reaction in dichloromethane. The proposed UF DOSY methodology may contribute towards a real-time diffusion NMR analysis of mixtures, to help in the identification of a sample’s components and in the analysis of molecular interactions.
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    “Diffusion NMR of out-of-equilibrium mixtures”

    Date:
    11
    Tuesday
    December
    2018
    Lecture / Seminar
    Time: 09:30
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Jean-Nicolas Dumez
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: The NMR spectra of molecular species in solution mixtures can be separated wit ... Read more The NMR spectra of molecular species in solution mixtures can be separated with diffusion-ordered NMR spectroscopy (DOSY), a ‘virtual chromatography’ approach based on the measurement of translational diffusion coefficients. Classic DOSY experiments, however, require several minutes are not applicable to many important time-evolving mixtures. Taking advantage of the concept of spatial encoding, we show here that DOSY data can be collected in a single scan of less than one second for several types of out-of-equilibrium mixtures. SPEN provides an acceleration of DOSY experiments by several orders of magnitude. SPEN DOSY pulse sequences are developed, that compensate for convection effects and are suitable for measurements in low-viscosity organic solvents, a requirement to monitor organic chemical reactions. We also show how to collect multiple consecutive scans from short-lived, non-renewable signals produced by dissolution dynamic nuclear polarisation (D-DNP), which is a versatile and powerful hyperpolarisation method. These methodological developments are supported by advanced numerical simulations, based on a Fokker-Plank formalism to describe simultaneously the spin and spatial dynamics. An exemple of hyperpolarised sample is given with a model mixture of small molecules, while the ability to monitor a reacting mixture is illustrated with a diamination reaction in dichloromethane. The proposed UF DOSY methodology may contribute towards a real-time diffusion NMR analysis of mixtures, to help in the identification of a sample’s components and in the analysis of molecular interactions.
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