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Aug 2020 • SPring-8/SACLA Research Report

Experimental Search For Difference-Frequency Generation Of Optical Radiation from Two-Color X-Ray Pulses

A Schori, D Borodin, K Tamasaku, Reis DA, Y Feng, Y Inubushi, M Yabashi, S Shwartz

The purpose of this beamtime was to observe difference-frequency generation of optical radiation from two-color x-ray pulses and to explore the possibility to use it as a method for the study of light matter interactions at atomic scale resolution. The experiment followed a detailed theoretical analysis of the effect [1]. We did not measure difference frequency generation during that beamtime due to technical challenges.

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Aug 2020 • Metamaterials, Metadevices, and Metasystems 2020 11460, 114600L, 2020

Active and dynamically tunable semiconductor resonators and metasurfaces

Tomer Lewi

We present our latest progress in the study of different tunable and active mechanisms in various materials that exhibit large modulation of optical constants and are used to implement active resonators and metasurfaces. We first discuss tuning of infrared Mie-resonant Si and Ge metasurfaces by modulating their free carrier density. We then move to discuss thermo-optic (TO) effects in Si, Ge and InSb and demonstrate tuning of Mie resonances by more than the resonance linewidth. Exploiting the peak TO coefficient of Si near its bandgap, we realize reconfigurable metasurfaces and tunable metafilters. We also show that phase transition materials such as VO2 can be used to implement active devices. We demonstrate electrically tunable Ge on VO2 resonators acting both as amplitude and phase modulators. Finally, we demonstrate ultra-wide dynamic tuning of PbTe meta-atoms. Taking advantage of the …

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Aug 2020 • The Open Access Journal of Science and Technology

Chiral characterization of materials using Raman spectroscopy

Hagit Aviv

Recently, developments in optical filters have enabled thefacile use of Raman spectroscopy to detect low-frequency vibrational (LFV) modes. We presented a new method for differentiating racemic from enantiopure crystals by using, for the first time, Raman spectroscopy to characterize the LFV modes of crystalline organic materials composed of chiral molecules. The LF-Raman spectra of racemic and enantiopure crystals exhibit a significant variation, which we attribute to different hydrogen-bond networks in the chiral crystal structures. Across a representative set of amino acids, we observed that when comparing racemic versus enantiopure crystals, the available LFV modes and their relative scattering intensity are strong functions of side chain polarity. Thus, LF-Raman can be used as a complementary method to the currently used methods for characterizing crystal’s chirality. The pharmaceutical industry is in need of new techniques to identify the chirality of solids due to regulatory and safety concerns regarding the biological activity of enantiomers. Since we found the LF-Raman spectra of racemic and enantiopure crystals are significantly different, we set out to demonstrate the capabilities of our method for chiral purity investigation. For that we used a model system based on chiral crystals of enantiopure, racemic crystals and their mixtures in various ratios. Using this method, we were able to identify small amounts, as low as 1% w/w, of an enantiomer in racemic crystals. Comparing the achieved sensitivity for enantiomeric excess measurement in chiral crystals to that of circular dichroism and X-ray diffraction measurements showed that LF …

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Aug 2020 • Trends in cell biology 30 (8), 640-652, 2020

Complex cartography: regulation of E2F transcription factors by cyclin F and ubiquitin

Michael J Emanuele, Taylor P Enrico, Ryan D Mouery, Danit Wasserman, Sapir Nachum, Amit Tzur

The E2F family of transcriptional regulators sits at the center of cell cycle gene expression and plays vital roles in normal and cancer cell cycles. Whereas control of E2Fs by the retinoblastoma family of proteins is well established, much less is known about their regulation by ubiquitin pathways. Recent studies placed the Skp1-Cul1-F-box-protein (SCF) family of E3 ubiquitin ligases with the F-box protein Cyclin F at the center of E2F regulation, demonstrating temporal proteolysis of both activator and atypical repressor E2Fs. Importantly, these E2F members, in particular activator E2F1 and repressors E2F7 and E2F8, form a feedback circuit at the crossroads of cell cycle and cell death. Moreover, Cyclin F functions in a reciprocal circuit with the cell cycle E3 ligase anaphase-promoting complex/cyclosome (APC/C), which also controls E2F7 and E2F8. This review focuses on the complex contours of feedback within this …

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Aug 2020 • Physical Review A

Quantization of the mean decay time for non-Hermitian quantum systems

Felix Thiel, David A Kessler, Eli Barkai

We show that the mean time, which a quantum particle needs to escape from a system to the environment, is quantized and independent from most dynamical details of the system. In particular, we consider a quantum system with a general Hermitian Hamiltonian H ̂ and one decay channel, through which probability dissipates to the environment with rate Γ. When the system is initially prepared exactly in the decay state, the mean decay time T is quantized and equal to w/(2 Γ). w is the number of distinct energy levels, ie, eigenvalues of H ̂, that have overlap with the decay state, and is also the winding number of a transform of the resolvent in the complex plane. Apart from the integer w, T is completely independent of the system's dynamics. The complete decay time distribution can be obtained from an electrostatic analogy and features rare events of very large dissipation times for parameter choices close to …

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Aug 2020 • Applied Physics Letters

A four-state magnetic tunnel junction switchable with spin-orbit torques

Shubhankar Das, Ariel Zaig, Moty Schultz, Susana Cardoso, Diana C Leitao, Lior Klein

We present a magnetic tunnel junction (MTJ) where its two ferromagnetic layers are in the form of a single ellipse (SE) and two-crossing ellipses (TCEs). The MTJ exhibits four distinct resistance states corresponding to the four remanent states of the TCE structure. Flowing current in an underlying Ta layer generates in the adjacent TCE structure spin–orbit torques, which induce field-free switching of the four-state MTJ between all its resistance states. The demonstrated four-state MTJ is an important step toward fabricating multi-level MTJs with numerous resistance states, which could be important in various spintronics applications, such as multi-level magnetic random access or neuromorphic memory.

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Aug 2020 • University of Southampton, 2020

Dataset: Laser-Induced Backward Transfer of Monolayer Graphene

Matthew Praeger, Symeon Papazoglou, Amaia Pesquera, Amaia Zerutuza, Adi Levi, Doron Naveh, Ioanna Zergioti, RW Eason, Benjamin Mills

Dataset relating to the journal article 'Laser-Induced Backward Transfer of Monolayer Graphene' , published in Applied Surface Science.

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Aug 2020 • Atmospheric Chemistry and Physics

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Archit Mehra, Yuwei Wang, Jordan E Krechmer, Andrew Lambe, Francesca Majluf, Melissa A Morris, Michael Priestley, Thomas J Bannan, Daniel J Bryant, Kelly L Pereira, Jacqueline F Hamilton, Andrew R Rickard, Mike J Newland, Harald Stark, Philip Croteau, John T Jayne, Douglas R Worsnop, Manjula R Canagaratna, Lin Wang, Hugh Coe

Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and are important for both ozone and secondary organic aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation that can lead to the formation of highly oxidised products. In this study we evaluate the gas-and particle-phase ions measured by online mass spectrometry during the hydroxyl radical oxidation of substituted C9-aromatic isomers (1, 3, 5-trimethylbenzene, 1, 2, 4-trimethylbenzene, propylbenzene and isopropylbenzene) and a substituted polyaromatic hydrocarbon (1-methylnaphthalene) under low-and medium-NOx conditions. A time-of-flight chemical ionisation mass spectrometer (ToF-CIMS) with iodide–anion ionisation was used with a filter inlet for gases and aerosols (FIGAERO) for the detection of products in the particle phase, while a Vocus proton-transfer-reaction mass spectrometer (Vocus-PTR-MS) was used for the detection of products in the gas phase. The signal of product ions observed in the mass spectra were compared for the different precursors and experimental conditions. The majority of mass spectral product signal in both the gas and particle phases comes from ions which are common to all precursors, though signal distributions are distinct for different VOCs. Gas-and particle-phase composition are distinct from one another. Ions corresponding to products contained in the near-explicit gas phase Master Chemical Mechanism (MCM version 3.3. 1) are utilised as a benchmark of …

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Aug 2020 • Atmospheric Chemistry and Physics

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Archit Mehra, Yuwei Wang, Jordan E Krechmer, Andrew Lambe, Francesca Majluf, Melissa A Morris, Michael Priestley, Thomas J Bannan, Daniel J Bryant, Kelly L Pereira, Jacqueline F Hamilton, Andrew R Rickard, Mike J Newland, Harald Stark, Philip Croteau, John T Jayne, Douglas R Worsnop, Manjula R Canagaratna, Lin Wang, Hugh Coe

Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and are important for both ozone and secondary organic aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation that can lead to the formation of highly oxidised products. In this study we evaluate the gas-and particle-phase ions measured by online mass spectrometry during the hydroxyl radical oxidation of substituted C9-aromatic isomers (1, 3, 5-trimethylbenzene, 1, 2, 4-trimethylbenzene, propylbenzene and isopropylbenzene) and a substituted polyaromatic hydrocarbon (1-methylnaphthalene) under low-and medium-NOx conditions. A time-of-flight chemical ionisation mass spectrometer (ToF-CIMS) with iodide–anion ionisation was used with a filter inlet for gases and aerosols (FIGAERO) for the detection of products in the particle phase, while a Vocus proton-transfer-reaction mass spectrometer (Vocus-PTR-MS) was used for the detection of products in the gas phase. The signal of product ions observed in the mass spectra were compared for the different precursors and experimental conditions. The majority of mass spectral product signal in both the gas and particle phases comes from ions which are common to all precursors, though signal distributions are distinct for different VOCs. Gas-and particle-phase composition are distinct from one another. Ions corresponding to products contained in the near-explicit gas phase Master Chemical Mechanism (MCM version 3.3. 1) are utilised as a benchmark of …

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Aug 2020 • Israel Journal of Chemistry 60 (8-9), 766-767, 2020

Computational Materials Science in Israel

Dan T Major, Leeor Kronik

Basic and applied research in materials science plays a significant role worldwide and it is therefore no wonder that the materials research scene in Israel is thriving. In fact, Israeli researchers in materials science have been recognized by many national and international awards, which are far too numerous to be discussed here. It suffices to mention the Nobel Prize awarded to Prof. Dan Shechtman for his discovery of quasicrystals. While many aspects of materials science are practical in nature, understanding and designing materials properties rely heavily on fundamental scientific research, leading to an increasing involvement of computational and theoretical chemistry and physics. Indeed, an independent area–computational materials science–has arisen and has become commonplace in materials research. This special issue highlights computational materials science work done in Israel. Theory and …

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Aug 2020 • Israel Journal of Chemistry 60 (8-9), 850-862, 2020

Review of Computational Studies of NCM Cathode Materials for Li‐ion Batteries

Arup Chakraborty, Sooraj Kunnikuruvan, Mudit Dixit, Dan T Major

Lithium‐ion based rechargeable batteries are considered among the most promising battery technologies because of the high energy‐ and power‐densities of these electrochemical devices. Computational studies on lithium ion batteries (LIBs) facilitate rationalization and prediction of many important experimentally observed properties, including atomic structure, thermal stability, electronic structure, ion diffusion pathways, equilibrium cell voltage, electrochemical activity, and surface behavior of electrode materials. In recent years, Ni, Co and Mn‐based (NCM) layered transition metal oxide positive electrode materials (LiNi1‐x‐yCoxMnyO2) have shown tremendous promise for high‐energy density LIBs, and these NCM‐based batteries are effectively commercialized. Here, we present an overview of recent theoretical work performed using first principles density functional theory on these layered cathode materials …

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Aug 2020 • International Journal of Biology and Chemistry

Composite materials based on orange and pomegranate peels for Сu (II) and Zn (II) ions extraction

AK Kenessova, GA Seilkhanova, AB Rakhym, Yi Mastai

This study investigated the method of obtaining of composite materials based on orange (OP) and pomegranate (PP) peels. The fruit peels were modified by polyethylene glycol (PEG). Sorption ability of obtained composite materials towards heavy metal ions (Zn and Cu) was studied. The effect of mass of composite materials and PEG concentration were studied. Optimal concentration of PEG was determined as 0.1%. The maximum removal degree of heavy metals was at 2 and 2.5 g per 100 ml of solution for orange and pomegranate peels respectively. Three different adsorption models were used to describe the sorption process (Langmuir, Freundlich, and BET). The most applicable for the sorption of Zn (II) and Cu (II) ions by both OP and PP is Freundlich theory. Hence, the sorption of Zn (II) and Cu (II) ions by modified peels of orange and pomerarnate occurs at heterogeneous system where the active centers are unevenly filled.

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Aug 2020 • Frontiers in microbiology

TrypOx, a novel eukaryotic homolog of the redox-regulated chaperone Hsp33 in Trypanosoma brucei

Samar Aramin, Rosi Fassler, Vaibhav Chikne, Mor Goldenberg, Tal Arian, Liat Kolet Eliaz, Oded Rimon, Oren Ram, Shulamit Michaeli, Dana Reichmann

ATP-independent chaperones are widespread across all domains of life and serve as the first line of defense during protein unfolding stresses. One of the known crucial chaperones for bacterial survival in a hostile environment (e.g. heat and oxidative stress) is the highly conserved, redox-regulated ATP-independent bacterial chaperone Hsp33. Using a bioinformatic analysis, we describe novel eukaryotic homologues of Hsp33 identified in eukaryotic pathogens belonging to the kinetoplastids, a family responsible for lethal human diseases such as Chagas disease as caused by Trypanosoma cruzi, African sleeping sickness caused by Trypanosoma brucei spp, and leishmaniasis pathologies delivered by various Leishmania species. During their pathogenic life cycle, kinetoplastids need to cope with elevated temperatures and oxidative stress, the same conditions which convert Hsp33 into a powerful chaperone in bacteria, thus preventing aggregation of a wide range of misfolded proteins. Here we focused on a functional characterization of the Hsp33 homologue in one of the members of the kinetoplastid family, T. brucei, (Tb927.6.2630), which we have named TrypOx. RNAi silencing of TrypOx led to a significant decrease in the survival of T.brucei under mild oxidative stress conditions, implying a protective role of TrypOx during the Trypanosomes growth. We then adopted a proteomics-driven approach to investigate the role of TrypOx in defining the oxidative stress response. Depletion of TrypOx significantly altered the abundance of proteins mediating redox homeostasis, linking TrypOx with the antioxidant system. Using biochemical …

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Aug 2020 • ChemElectroChem

Interaction between Electrolytes and Sb2O3‐Based Electrodes in Sodium Batteries: Uncovering the Detrimental Effects of Diglyme

Kristina Pfeifer, Miryam Fayena Greenstein, Doron Aurbach, Xianlin Luo, Helmut Ehrenberg, Sonia Dsoke

Conversion materials are promising to improve the energy density of sodium-ion-batteries (NIB). Nevertheless, they suffer from the drawback of phase transitions and pronounced volume changes during cycling, which causes cell instability. When using these types of electrodes, all cell-components have to be adjusted. In this study, a tremendous influence of the electrolyte solution on Sb2O3 conversion electrodes for NIBs is discussed. Solutions based on three solvents and solvent combinations established for NIBs, ethylene carbonate/dimethyl carbonate (EC/DMC), EC/DMC+ 5% fluoroethylene carbonate (FEC), and diglyme, lead to a massively divergent electrochemical behavior of the same Sb2O3 electrode. Sb2O3 demonstrates the highest stability in solutions containing FEC, because this component forms a flexible, protecting surface film that prevent disintegration. One key finding of this work is that electrolyte solutions based on ether solvents like diglyme can remove Sb-ions from Sb2O3 during cycling. Diglyme has the ability to coordinate and extract Sb3+ during the oxidation of Sb2O3. This leads to contaminations of all cell components and a strong capacity loss together with an irregular electrochemical signature. Due to its poor reactivity at low potentials, diglyme forms a thin or even no surface layer. Thereby, there are no protecting films on the Sb2O3 electrodes that can avoid Sb3+ ion dissolution. A critical examination of the electrolyte solutions components’ impact is essential to match them with conversion reaction anodes.

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Aug 2020 • IEEE Photonics Journal

Depth scattering characterization of multi-layer turbid media based on iterative multi-plane reflectance measurements

I Yariv, H Duadi, D Fixler

Overcoming opaque barriers beyond the penetration depth is based on light-matter interactions, with applications in biomedical optics, material science and security. In wave propagation, scattering is the amount of disorder, mostly treated as a disturbance. Scattered light variations allow overcoming opaque barriers. In order to separate turbid medium layers, absorption-based contrast is commonly used. This paper presents the two-layer study of a noninvasive scattering-based technique. The iterative multi-plane optical property extraction (IMOPE) technique assesses scattering by reconstructing the light phase. The reflection-based IMOPE detects different scattering layers with 0.2 mm −1 sensitivity at different depths, behind layers up to 6 mm thick.

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Aug 2020 • ACS omega

Two Orders of Magnitude Boost in the Detection Limit of Droplet-Based Micro-Magnetofluidics with Planar Hall Effect Sensors

Julian Schütt, Rico Illing, Oleksii Volkov, Tobias Kosub, Pablo Nicolás Granell, Hariharan Nhalil, Jürgen Fassbender, Lior Klein, Asaf Grosz, Denys Makarov

Magnetofluidics is a dynamic research field, which requires novel sensor solutions to boost the detection limit of tiny quantities of magnetized objects. Here, we present a sensing strategy relying on planar Hall effect sensors in droplet-based micro-magnetofluidics for the detection of a multiphase liquid flow, i.e., superparamagnetic aqueous droplets in an oil carrier phase. The high resolution of the sensor allows the detection of nanoliter-sized superparamagnetic droplets with a concentration of 0.58 mg/cm3, even when they are biased in a geomagnetic field only. The limit of detection can be boosted another order of magnitude, reaching 0.04 mg/cm3 (1.4 million particles in a single 100 nL droplet) when a magnetic field of 5 mT is applied to bias the droplets. With this performance, our sensing platform outperforms the state-of-the-art solutions in droplet-based micro-magnetofluidics by a factor of 100. This allows us …

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Aug 2020 • Energy Storage Materials

Alkylated LixSiyOz Coating for Stabilization of Li-rich Layered Oxide Cathodes

Rosy, Shira Haber, Eliran Evenstein, Arka Saha, Olga Brontvein, Yosi Kratish, Dmitry Bravo‐Zhivotovskii, Yitzhak Apeloig, Michal Leskes, Malachi Noked

The commercialization of the high energy, lithium, and manganese-rich NCM (LMR-NCM) is impeded by its complex interfacial electrochemical processes, oxygen release, and surface degradation. Here, we introduced t-butyl-dimethylsilyllithium as a single-source precursor for depositing LixSiyOz with an integrated network of siloxane moieties as an artificial cathode/electrolyte interphase (ACEI) which stabilizes LMR-NCM by mitigating oxygen release, electrolyte degradation and preventing fractures. Using solid-state NMR coupled with dynamic nuclear polarization, detailed molecular-level characterization of the ACEI is presented. The proposed CEI enabled improved energy-density at high rates (644 Wh.kg-1, compared to uncoated material with 457 Wh.kg-1 at 4C) with suppressed parasitic reactions and O2 evolution. The efficacy of the CEI is demonstrated in full graphite/LMR-NCM pouch cells with ~ 35 …

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Aug 2020 • Cell Stem Cell

LEFTY1 is a dual-SMAD inhibitor that promotes mammary progenitor growth and tumorigenesis

Maider Zabala, Neethan A Lobo, Jane Antony, Luuk S Heitink, Gunsagar S Gulati, Jessica Lam, Natesh Parashurama, Kassandra Sanchez, Maddalena Adorno, Shaheen S Sikandar, Angera H Kuo, Dalong Qian, Tomer Kalisky, Sopheak Sim, Linus Li, Frederick M Dirbas, George Somlo, Aaron Newman, Stephen R Quake, Michael F Clarke

SMAD pathways govern epithelial proliferation, and transforming growth factor β (TGF-β and BMP signaling through SMAD members has distinct effects on mammary development and homeostasis. Here, we show that LEFTY1, a secreted inhibitor of NODAL/SMAD2 signaling, is produced by mammary progenitor cells and, concomitantly, suppresses SMAD2 and SMAD5 signaling to promote long-term proliferation of normal and malignant mammary epithelial cells. In contrast, BMP7, a NODAL antagonist with context-dependent functions, is produced by basal cells and restrains progenitor cell proliferation. In normal mouse epithelium, LEFTY1 expression in a subset of luminal cells and rare basal cells opposes BMP7 to promote ductal branching. LEFTY1 binds BMPR2 to suppress BMP7-induced activation of SMAD5, and this LEFTY1-BMPR2 interaction is specific to tumor-initiating cells in triple-negative breast …

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Aug 2020 • ACS Applied Energy Materials

Carbon-Supported PtNi Nanocrystals for Alkaline Oxygen Reduction and Evolution Reactions: Electrochemical Activity and Durability upon Accelerated Stress Tests

Victor Shokhen, Melina Zysler, Meital Shviro, David Zitoun, Marian Chatenet

The PtNi catalyst is among the most active electrocatalysts for the oxygen reduction reaction, but its stability in operation is uncertain. Intuitively, alkaline environments lead to milder degradations than acidic ones, although carbon-supported Pt-group metal nanoparticles are particularly degraded even in dilute alkaline electrolytes. To date, PtNi catalyst durability has not been characterized for alkaline oxygen reduction and evolution reactions (ORR and OER). Herein, carbon-supported shape-controlled PtNi catalysts were compared in terms of activity and durability during alkaline ORR and OER. The PtNi catalysts are shape-controlled Pt-rich alloy, Ni-rich alloy, and Pt core/Ni shell (Pt@Ni) nanoparticles synthesized on Vulcan XC72R carbon. Their morphology and composition were evaluated by identical-location transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction pre- and …

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Jul 2020 • Electrochimica Acta 354, 136771, 2020

On the challenge of large energy storage by electrochemical devices

Satyanarayana Maddukuri, David Malka, Munseok S Chae, Yuval Elias, Shalom Luski, Doron Aurbach

This paper reviews work that promotes the effective use of renewable energy sources (solar and wind) by developing technologies for large energy storage, concentrating on electrochemical devices. Unfortunately, we are not far from a non-return situation related to global warming due to green-house gasses emission, 88% of which is contributed through release of CO2 by combusting fossil fuels. Major contributors to CO2 emission are power stations that produce electricity. Only a massive replacement of fossil fuels combustion by photovoltaic solar panels and wind turbines for electricity production can reduce drastically the detrimental CO2 emission. The success of using renewable energy depends on the availability of technologies for large energy storage. We believe that modern electrochemistry can provide them. We review herein relevant options. While hydrogen based technology using fuel cells and flow …

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Jul 2020 • Journal of biophotonics

Reducing data acquisition for light‐sheet microscopy by extrapolation between imaged planes

Ziv Shemesh, Gal Chaimovich, Liron Gino, Nisan Ozana, Jonathan Nylk, Kishan Dholakia, Zeev Zalevsky

Light‐sheet fluorescence microscopy (LSFM) is a powerful technique that can provide high‐resolution images of biological samples. Therefore, this technique offers significant improvement for three‐dimensional (3D) imaging of living cells. However, producing high‐resolution 3D images of a single cell or biological tissues, normally requires high acquisition rate of focal planes, which means a large amount of sample sections. Consequently, it consumes a vast amount of processing time and memory, especially when studying real‐time processes inside living cells. We describe an approach to minimize data acquisition by interpolation between planes using a phase retrieval algorithm. We demonstrate this approach on LSFM data sets and show reconstruction of intermediate sections of the sparse samples. Since this method diminishes the required amount of acquisition focal planes, it also reduces acquisition time …

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