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Nov 2019 • The Journal of Physical Chemistry C

Visualization of plasmon-induced hot electrons by scanning electron microscopy

Elad Segal, Matan Galanty, Hannah Aharon, Adi Salomon

We show that scanning electron microscopy imaging can indicate hot-electron formation in aluminum plasmonic nanostructures composed of five triangular cavities. A very strong secondary electron emission was observed, up to 150 nm from the plasmonic structure. The secondary electron emission depends on the acceleration voltage, the distance between the plasmonic cavities, the metal type, and the roughness of the surface. Furthermore, the formation of hot electrons was used to increase the efficiency of an optoelectronic device.

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Nov 2019 • The Journal of Physical Chemistry B

Backbone-constrained peptides: temperature and secondary structure affect solid-state electron transport

Cunlan Guo, Jingxian Yu, John R Horsley, Mordechai Sheves, David Cahen, Andrew D Abell

The primary sequence and secondary structure of a peptide are crucial to charge migration, not only in solution (electron transfer, ET), but also in the solid-state (electron transport, ETp). Hence, understanding the charge migration mechanisms is fundamental to the development of biomolecular devices and sensors. We report studies on four Aib-containing helical peptide analogues: two acyclic linear peptides with one and two electron-rich alkene-based side chains, respectively, and two peptides that are further rigidified into a macrocycle by a side bridge constraint, containing one or no alkene. ETp was investigated across Au/peptide/Au junctions, between 80 and 340 K in combination with the molecular dynamic (MD) simulations. The results reveal that the helical structure of the peptide and electron-rich side chain both facilitate the ETp. As temperature increases, the loss of helical structure, change of monolayer …

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Nov 2019 • Advanced Biosystems

An integrated microfluidics approach for personalized cancer drug sensitivity and resistance assay

Inna Desyatnik, Matan Krasner, Ludmila Frolov, Maria Ronen, Ortal Guy, Danit Wasserman, Amit Tzur, Dorit Avrahami, Efrat Barbiro‐Michaely, Doron Gerber

Cancer is the second leading cause of death globally. Matching proper treatment and dosage is crucial for a positive outcome. Any given drug may affect patients with similar tumors differently. Personalized medicine aims to address this issue. Unfortunately, most cancer samples cannot be expanded in culture, limiting conventional cell‐based testing. Herein, presented is a microfluidic device that combines a drug microarray with cell microscopy. The device can perform 512 experiments to test chemosensitivity and resistance to a drug array. MCF7 and 293T cells are cultured inside the device and their chemosensitivity and resistance to docetaxel, applied at various concentrations, are determined. Cell mortality is determined as a function of drug concentration and exposure time. It is found that both cell types form cluster morphology within the device, not evident in conventional tissue culture under similar …

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Nov 2019 • OSA Continuum

Ultrafast twin-peak rogue waves in a vector field

Avi Klein, Shir Shahal, Sara Meir, Hamootal Duadi, Kfir Sulimany, Ohad Lib, Hadar Steinberg, Stanislav A Kolpakov, Moti Fridman

Rogue waves, which were first described as an oceanographic phenomenon, constitute an important factor in the dynamics of many physical systems. Most of these systems were analyzed by scalar fields, while some of them, and specifically in optics, are described by a vector field. Thus, they differ from scalar systems in several crucial aspects. In this work, we study experimentally twin-peak rogue waves with a temporal imaging system capable of measuring the Stokes vectors as a function of time. We found that the two peaks in optical twin-peak rogue waves have orthogonal states of polarization and similar intensities. We observed this with two different systems, however, we do not have a theoretical explanation for this phenomena and could not explain it with current models.

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Nov 2019 • Nature methods

Genome-wide quantification of ADAR adenosine-to-inosine RNA editing activity

Shalom Hillel Roth, Erez Y Levanon, Eli Eisenberg

Adenosine-to-inosine (A-to-I) RNA editing by the adenosine deaminase that acts on RNA (ADAR) enzymes is a common RNA modification, preventing false activation of the innate immune system by endogenous double-stranded RNAs. Methods for quantification of ADAR activity are sought after, due to an increasing interest in the role of ADARs in cancer and autoimmune disorders, as well as attempts to harness the ADAR enzymes for RNA engineering. Here, we present the Alu editing index (AEI), a robust and simple-to-use computational tool devised for this purpose. We describe its properties and demonstrate its superiority to current quantification methods of ADAR activity. The AEI is used to map global editing across a large dataset of healthy human samples and identify putative regulators of ADAR, as well as previously unknown factors affecting the observed Alu editing levels. These should be taken into …

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Nov 2019 • Journal of Solid State Electrochemistry

Unveiling ionic diffusion in MgNiMnO4 cathode material for Mg-ion batteries via combined computational and experimental studies

H Shasha, N Yatom, M Prill, J Zaffran, S Biswas, D Aurbach, M Caspary Toroker, Y Ein-Eli

A major challenge in the field of rechargeable Mg batteries is the development of high voltage/high capacity cathode materials. Naturally, a first step in a general search of cathode materials for Mg batteries should be following the plethora of cathode materials relevant to Li-ion batteries. Indeed, several compounds that were thoroughly studied in connection to Li-ion batteries were found to interact reversibly with Mg ions, as well. The functionality of metal ion batteries relies on an efficient ionic transport within the electrodes’ active mass. In this study, we examined the extreme case of the MgNiMnO4 material, using a combination of computational and experimental techniques. The scientific question being raised in this study was whether Mg ions can be extracted electrochemically from this compound. The experiments provided a negative answer and calculations based on density functional theory (DFT …

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Nov 2019 • Small

Porous Materials: Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain …

Neta Zilony‐Hanin, Michal Rosenberg, Michal Richman, Ronen Yehuda, Hadas Schori, Menachem Motiei, Shai Rahimipour, Alexander Groisman, Ester Segal, Orit Shefi

In article number 1904203, Ester Segal, Orit Shefi, and co-workers safely implant or biolistically introduce degradable porous silicon carriers into the brains of mice for continuous and effective release of nerve growth factor, a neuroprotective drug for Alzheimer's disease.

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Nov 2019 • Micromachines

Configuration and design of electromagnets for rapid and precise manipulation of magnetic beads in biosensing applications

Moshe Stern, Meir Cohen, Amos Danielli

Rapid and precise manipulation of magnetic beads on the nano and micro scales is essential in many biosensing applications, such as separating target molecules from background molecules and detecting specific proteins and DNA sequences in plasma. Accurately moving magnetic beads back and forth requires at least two adjustable magnetic field gradients. Unlike permanent magnets, electromagnets are easy to design and can produce strong and adjustable magnetic field gradients without mechanical motion, making them desirable for use in robust and safe medical devices. However, using multiple magnetic field sources to manipulate magnetic beads presents several challenges, including overlapping magnetic fields, added bulk, increased cost, and reduced durability. Here, we provide a thorough analysis, including analytical calculations, numerical simulations, and experimental measurements, of using two electromagnets to manipulate magnetic beads inside a miniature glass cell. We analyze and experimentally demonstrate different aspects of the electromagnets’ design, such as their mutual influence, the advantages and disadvantages of different pole tip geometries, and the correlation between the electromagnets’ positions and the beads’ aggregation during movement. Finally, we have devised a protocol to maximize the magnetic forces acting on magnetic beads in a two-electromagnet setup while minimizing the electromagnets’ size. We used two such electromagnets in a small footprint magnetic modulation biosensing system and detected as little as 13 ng/L of recombinant Zika virus antibodies, which enables detection of …

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Nov 2019 • PLoS genetics

Availability of splicing factors in the nucleoplasm can regulate the release of mRNA from the gene after transcription

Hodaya Hochberg-Laufer, Noa Neufeld, Yehuda Brody, Shani Nadav-Eliyahu, Rakefet Ben-Yishay, Yaron Shav-Tal

Gene expression dynamics can be measured in single living cells. Using a detectable transcriptionally active gene in living cells, we previously found that an mRNA undergoing several splicing events was retained at this gene after transcription until completion of mRNA processing. To determine the reason for this delay in release and whether mRNA retention on the gene might depend on splicing factor availability, we modulated the levels of splicing factors in the nucleus. Increasing the abundance of the diffusing fraction of splicing factors by their overexpression or by Clk1 kinase overexpression to disassemble nuclear speckles, led to a reduction in splicing factor residence times on the active gene, and the retained mRNA was rapidly released from the gene. Other treatments such as overexpression of a mutant inactive Clk1, the downregulation of MALAT1 lncRNA or of the Son protein, or the overexpression of the splicing factor import factor TNPO3, did not affect the dynamics of mRNA release from the gene. We found that the faster release of the mRNA from the gene mediated by increased availability of splicing factors, was dependent on the RS domain of the splicing factors and its phosphorylation state. We propose that the relative abundancies of splicing factors in the nucleoplasm can affect their availability for the splicing events taking place, and regulate the kinetics of mRNA release from the gene after processing.

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Nov 2019 • ECS Transactions

Effect of superhalogen anions on the electrochemical behavior of V2O5 electrodes in redox reactions with lithium in EC-DMC/Li-salt solutions

Raisa Apostolova, Boris Markovsky, Doron Aurbach, Elena Shembel

It was established that the number of active sites for the insertion/extraction of lithium ions in/from the V 2 O 5 structure in EC-DMC/Li-salt solutions depends on superhalogen anion. Unstable sites and their dependence on superhalogen anion (PF 6–, AsF 6–, ClO 4–) are identified during discharge-charge cycling of V 2 O 5 electrodes. The number of open sites in V 2 O 5 depends on the structure stability and conductivity of V 2 O 5. To increase the structure stability in phase transitions, we propose the electrochemical doping of V 2 O 5 by Mn 2+. We propose that the conductivity and rate characteristics of V 2 O 5 could be increased by its co-deposition with conducting polymer of polyaniline type. Using theoretical calculation simulations assumptions have been made regarding the difference in the solvation of lithium ions in an EC/DMC mixture with different ratios of the solvents.

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Nov 2019 • 2019 Asia Communications and Photonics Conference (ACP), 1-3, 2019

Sequence-coded coherent laser range-finder with hundreds of photons sensitivity

Keren Shemer, Gil Bashan, H Hagai Diamandi, Yosef Lodnon, Alon Charni, Tzur Raanan, Yochai Israelashvili, Itzik Cohen, Nadav Levanon, Avi Zadok

Coherent detection of a sequence coded laser range finder is demonstrated over fiber. The shot noise limited receiver sensitivity reaches 800 photons, and 0.002 photons per bit. Signals of 250 femto-Watt power are successfully compressed.

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Nov 2019 • Scientific reports

Assembly along lines in boundary-driven dynamical system

Kulveer Singh, Yitzhak Rabin

We introduce a simple dynamical rule in which each particle locates a particle that is farthest from it and moves towards it. Repeated application of this algorithm results in the formation of unusual dynamical patterns: during the process of assembly the system self-organizes into slices of low particle density separated by lines of increasingly high particle density along which most particles move. As the process proceeds, pairs of lines meet and merge with each other until a single line remains and particles move along it towards the zone of assembly. We show that this pattern is governed by particles (attractors) situated on the instantaneous outer boundary of the system and that both in two and in three dimensions the lines are formed by zigzag motion of a particle towards a pair of nearly equidistant attractors. This novel line-dominated assembly is very different from the local assembly in which particles that move …

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Nov 2019 • Nanophotonics

Photonic realization of erasure-based nonlocal measurements

Wei-Wei Pan, Xiao-Ye Xu, Eliahu Cohen, Qin-Qin Wang, Zhe Chen, Munsif Jan, Yong-Jian Han, Chuan-Feng Li, Guang-Can Guo

Relativity theory severely restricts the ability to perform nonlocal measurements in quantum mechanics. Studying such nonlocal schemes may thus reveal insights regarding the relations between these two fundamental theories. Therefore, for the last several decades, nonlocal measurements have stimulated considerable interest. However, the experimental implementation of nonlocal measurements imposes profound restrictions because the interaction Hamiltonian cannot contain, in general, nonlocal observables such as the product of local observables belonging to different particles at spacelike-separated regions. In this work, we experimentally realize a scheme for nonlocal measurements with the aid of probabilistic quantum erasure. We apply this scheme to the tasks of performing high-accuracy nonlocal measurements of the parity, as well as measurements in the Bell basis, which do not necessitate classical …

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Nov 2019 • Physical Review Research

Theory of nonlinear interactions between x rays and optical radiation in crystals

Ron Cohen, Sharon Shwartz

We show that the nonlinear interactions between x rays and longer wavelengths in crystals depend strongly on the band structure and related properties. Consequently, these types of interactions can be used as a powerful probe for fundamental properties of crystalline bulk materials. In contrast to previous work that highlighted that these types of nonlinear interactions can provide microscopic information on the valence electrons at the atomic scale resolution, we show that these interactions also contain information that is related to the periodic potential of the crystal. We explain how it is possible to distinguish between the two contributions. Our work indicates on the possibility for the development of novel multidimensional pump-probe metrology techniques that will provide spectroscopic information combined with structural information including ultrafast dynamics at the atomic scale.

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Nov 2019 • The Journal of chemical physics

Clusters of betaine with positive and negative ions: Evidence for the betaine tetramer being magic

Adva Ben Yaacov, Lei Chen, Lihi Musbat, Maria Nihamkin, Alexander Kaiser, Yoni Toker

Betaine (Bet) is a pure zwitterion with an extraordinarily large dipole moment, which allows it to form stable clusters in the gas phase of the form X±BetN, where X± is a positive or negative ion. We show here that such clusters have a prominent magic number at N = 4 for all X± ions used in this work. Nevertheless, we observe a marked difference in the fragmentation pattern of anionic and cationic clusters: while cationic clusters fragment by evaporating one betaine monomer at a time, fragmentation of anionic clusters is through fission resulting in the emission of one or several betaine molecules. Theoretical calculations show that charged betaine tetramers have a square like structure with the central ion lying above the cluster plane and explain the difference in fragmentation patterns as a result of the charge distribution within the betaine molecule.

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Nov 2019 • Israel Journal of Chemistry 59 (11-12), 961-961, 2019

Magnetic Resonance in Biology

Sharon Ruthstein

This special issue is dedicated to new advances in the applications of magnetic resonance (MR) methods to the study of biological systems. MR spectroscopy is a nondestructive technique that can be used to characterize a wide variety of systems. Sustained development of both methodology and instrumentation have established MR as a powerful technology with applications in basic science, medicine, drug development, and numerous important branches of industry. By providing precise structural information at the atomic level, MR is also the only method for accurate determination of molecular structure in solution.When Felix Bloch and Edward Purcell were awarded the Nobel Prize in 1952 for having successfully detected nuclear magnetic resonance (NMR) signals six years earlier in solid paraffin and in water, respectively, MR was a fledgling field mainly in the hands of physicists. This, however, changed …

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Nov 2019 • arXiv preprint arXiv:1911.07812

Wavefront Shaping of the Pump in Multimode Fiber Amplifiers; The Gain-Dependent Transmission Matrix

Tom Sperber, Vincent Billault, Patrick Sebbah, Sylvain Gigan

Wavefront shaping techniques allow the control of the transport of light through many types of scattering or complex media, among them multimode fibers. The case of a multimode fiber which is also a gain medium presents further intriguing prospects for control, due to the possibility of wavefront shaping not only the signal light amplified by the medium, but also the pump light absorbed within it. Provided that the lightwave used for pumping is coherent, its shaping prior to injection will affect the complex, speckle-like spatial patterns of excitation within the amplifier volume, which in turn will act upon the signal as heterogeneous gain. We introduce a new theoretical model which captures the essential features of a multimode amplifying fiber pumped by a coherent beam with configurable modal content, allowing the calculation of the gain-dependent transmission matrix. We numerically implement our model to explore the extent to which one may control the amplified light in the spatial-domain, by shaping the pump; we demonstrate a significant ability of manipulation, as well as several interesting physical mechanisms limiting it. In particular, we show how taking into account the cross-contributions between all guided modes within the fiber is essential for understanding the full range of the signal sensitivity to the choice of pump shaping.

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Nov 2019 • Asia Communications and Photonics Conference, S3A. 1, 2019

Forward Stimulated Brillouin Scattering in Optical Fibers and its Applications

Avi Zadok

Forward stimulated Brillouin scattering couples between two co-propagating optical fields and a transverse acoustic mode of an optical fiber. Applications in sensing of media outside the fiber cladding and coupling among multiple cores are discussed.

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Oct 2019 • 2019 International Topical Meeting on Microwave Photonics (MWP), 1-4, 2019

An Integrated Discrete-Time Microwave Photonic Filter Using Surface Acoustic Waves in Silicon

Dvir Munk, Moshe Katzman, Mirit Hen, Maayan Priel, Arik Bergman, Avi Zadok

An integrated discrete-time microwave-photonic filter is implemented in standard silicon-on-insulator based on opto-mechanical interactions. Radio-frequency modulation of an incident optical pump is converted into slow-moving surface acoustic waves. The surface waves are delayed by up to 40 ns over 150 microns on-chip. Signals are recovered in the optical domain through photo-elastic modulation of probe light in multiple standard waveguides along the surface acoustic waves path. Devices do not require the suspension of silicon structures, piezo-electric actuation or hybrid material integration. A six-tap filter is demonstrated experimentally, with a central frequency, free spectral range and passbands width of 2.4 GHz, 125 MHz and 20 MHz, respectively. The measured transfer function is in excellent agreement with design. The results establish a new concept for integrated microwave photonics processing in …

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Oct 2019 • JOSA A

Broadband field-of-view expansion using a pair of digital micromirror devices

Daniel Dahan, Ami Yaacobi, Gil Aharonovich, Ephraim Pinsky, Zeev Zalevsky

Broadband field-of-view expansion using computational optics methods is presented. A pair of chirp gratings, implemented by digital micromirror devices, is placed on the optical entrance pupil plane of an optical system. The gratings perform achromatic translations of the image across the camera, and a wide image is reconstructed by a post-processing procedure. Optical design for such a system is proposed, and physical analysis shows the considerations of using these optical elements. All methods are established by simulations and experiments.

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Oct 2019

Genome wide quantification of A-to-I RNA editing activity

Shalom Hillel Roth, Erez Y Levanon, Eli Eisenberg

Adenosine to inosine (A-to-I) RNA editing by the ADAR enzymes is a common RNA modification, preventing false activation of the innate immune system by endogenous dsRNAs. Methods for quantification of ADAR activity are sought after, due to an increasing interest in the role of ADARs in cancer and auto-immune disorders, as well as attempts to harness the ADAR enzymes for RNA engineering. Here we present the Alu Editing Index (AEI), a robust and simple-to-use computational tool devised for this purpose that produces a single number representing the global editing level from BAM files. The AEI tool is available at https://github. com/a2iEditing/RNAEditingIndexer

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