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Dec 2019 • Nanomaterials

Optical Polarization Sensitive Ultra-Fast Switching and Photo-Electrical Device

Jérémy Belhassen, Zeev Zalevsky, Avi Karsenty

Ultra-fast electrical switches activated with an optical-polarized light trigger, also called photo-polarized activated electrical switches, are presented. A set of new transistor circuits is switched by light from above, illuminating deep V-grooves, whose angle is sensitive to the polarization of the incident. Thus, this application may serve for encryption/decryption devices since the strongest electrical responsivity is only obtained for very specific spatial polarization directions of the illumination beam. When this V-groove is sufficiently narrow, the device mainly responds to one polarization and not to the other. In such a way, electrons are generated only for one specific polarization. While the nature of the data remains electronic, the modulation control is optic, creating a photo-induced current depending on the polarization direction. This coupled device acts as a polarization modulator as well as an intensity modulator. The article focuses on the integration of several devices in different configurations of circuitry: dual, triple, and multi-element. Case studies of several adjacent devices are presented with varying critical variables, such as the V-groove aperture dimensions. Analytical models and complementary numerical analyses are presented for the future smooth integration into Complementary Metal-Oxide-Semiconductor (CMOS) technology. View Full-Text

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Dec 2019 • IEEE Journal of Selected Topics in Quantum Electronics

Opto-mechanical interactions in multi-core optical fibers and their applications

Hilel Hagai Diamandi, Yosef London, Arik Bergman, Gil Bashan, Javier Madrigal, David Barrera, Salvador Sales, Avi Zadok

Optical fibers containing multiple cores are being developed towards capacity enhancement in space-division multiplexed optical communication networks. In many cases, the fibers are designed for negligible direct coupling of optical power among the cores. The cores remain, however, embedded in a single, mechanically-unified cladding. Elastic (or acoustic) modes supported by the fiber cladding geometry are in overlap with multiple cores. Acoustic waves may be stimulated by light in any core through electrostriction. Once excited, the acoustic waves may induce photo-elastic perturbations to optical waves in other cores as well. Such opto-mechanical coupling gives rise to inter-core cross-phase modulation effects, even when direct optical crosstalk is very weak. The cross-phase modulation spectrum reaches hundreds of megahertz frequencies. It may consist of discrete and narrow peaks, or may become quasi …

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Dec 2019 • The Journal of chemical physics

Anodic decomposition of surface films on high voltage spinel surfaces—Density function theory and experimental study

Kevin Leung, Rosy, Malachi Noked

Oxidative decomposition of organic-solvent-based liquid electrolytes at cathode material interfaces has been identified as the main reason for rapid capacity fade in high-voltage lithium ion batteries. The evolution of “cathode electrolyte interphase” (CEI) films, partly or completely consisting of electrolyte decomposition products, has also recently been demonstrated to correlate with battery cycling behavior at high potentials. Using density functional theory calculations, the hybrid PBE0 functional, and the (001) surfaces of spinel oxides as models, we examine these two interrelated processes. Consistent with previous calculations, ethylene carbonate (EC) solvent molecules are predicted to be readily oxidized on the LixMn2O4 (001) surface at modest operational voltages, forming adsorbed organic fragments. Further oxidative decomposition of such CEI fragments to release CO2 gas is however predicted to require …

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Dec 2019 • The journal of physical chemistry letters

Solid-state electron transport via the protein azurin is temperature-independent down to 4 K

Ben Kayser, Jerry A Fereiro, Rajarshi Bhattacharyya, Sidney R Cohen, Ayelet Vilan, Israel Pecht, Mordechai Sheves, David Cahen

Solid-state electronic transport (ETp) via the electron-transfer copper protein azurin (Az) was measured in Au/Az/Au junction configurations down to 4 K, the lowest temperature for solid-state protein-based junctions. Not only does lowering the temperature help when observing fine features of electronic transport, but it also limits possible electron transport mechanisms. Practically, wire-bonded devices-on-chip, carrying Az-based microscopic junctions, were measured in liquid He, minimizing temperature gradients across the samples. Much smaller junctions, in conducting-probe atomic force microscopy measurements, served, between room temperature and the protein’s denaturation temperature (∼323 K), to check that conductance behavior is independent of device configuration or contact nature and thus is a property of the protein itself. Temperature-independent currents were observed from ∼320 to 4 K. The …

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Dec 2019 • MRS Bulletin

There’sa lithium battery in your future

Rachel Berkowitz, Doron Aurbach

Battery technology has come a long way since September 1899, when Ferdinand Porsche’s electric powered car won its first road race. The “Egger-Lohner electric C.2 Phaeton” carried a Tudor brand lead-acid battery that weighed 500 kg and propelled the 1350-kg vehicle with 3 hp (2.2 kW for 3–5 h) for 80 km.

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Dec 2019 • Acs Photonics

Single-photon, time-gated, phasor-based fluorescence lifetime imaging through highly scattering medium

Rinat Ankri, Arkaprabha Basu, Arin Can Ulku, Claudio Bruschini, Edoardo Charbon, Shimon Weiss, Xavier Michalet

Fluorescence lifetime imaging (FLI) is increasingly recognized as a powerful tool for biochemical and cellular investigations, including in vivo applications. Fluorescence lifetime is an intrinsic characteristic of any fluorescent dye which, to a large extent, does not depend on excitation intensity and signal level. In particular, it allows distinguishing dyes with similar emission spectra, offering additional multiplexing capabilities. However, in vivo FLI in the visible range is complicated by the contamination by (i) tissue autofluorescence, which decreases contrast, and by (ii) light scattering and absorption in tissues, which significantly reduce fluorescence intensity and modify the temporal profile of the signal. Here, we demonstrate how these issues can be accounted for and overcome, using a new time-gated single-photon avalanche diode array camera, SwissSPAD2, combined with phasor analysis to provide a simple and …

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Dec 2019 • Scientific reports

Unprecedented efficient electron transport across Au nanoparticles with up to 25-nm insulating SiO2-shells

Chuanping Li, Chen Xu, David Cahen, Yongdong Jin

Quantum tunneling is the basis of molecular electronics, but often its electron transport range is too short to overcome technical defects caused by downscaling of electronic devices, which limits the development of molecular-/nano-electronics. Marrying electronics with plasmonics may well present a revolutionary way to meet this challenge as it can manipulate electron flow with plasmonics at the nanoscale. Here we report on unusually efficient temperature-independent electron transport, with some photoconductivity, across a new type of junction with active plasmonics. The junction is made by assembly of SiO 2 shell-insulated Au nanoparticles (Au@ SiO 2 NPs) into dense nanomembranes of a few Au@ SiO 2 layers thick and transport is measured across these membranes. We propose that the mechanism is plasmon-enabled transport, possibly tunneling (as it is temperature-independent). Unprecedentedly ultra …

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Dec 2019 • Brain

Biallelic DMXL2 mutations impair autophagy and cause Ohtahara syndrome with progressive course

Alessandro Esposito, Antonio Falace, Matias Wagner, Moran Gal, Davide Mei, Valerio Conti, Tiziana Pisano, Davide Aprile, Maria Sabina Cerullo, Antonio De Fusco, Silvia Giovedì, Annette Seibt, Daniella Magen, Tilman Polster, Ayelet Eran, Sarah L Stenton, Chiara Fiorillo, Sarit Ravid, Ertan Mayatepek, Hava Hafner, Saskia Wortmann, Erez Y Levanon, Carla Marini, Hanna Mandel, Fabio Benfenati, Felix Distelmaier, Anna Fassio, Renzo Guerrini

Ohtahara syndrome, early infantile epileptic encephalopathy with a suppression burst EEG pattern, is an aetiologically heterogeneous condition starting in the first weeks or months of life with intractable seizures and profound developmental disability. Using whole exome sequencing, we identified biallelic DMXL2 mutations in three sibling pairs with Ohtahara syndrome, belonging to three unrelated families. Siblings in Family 1 were compound heterozygous for the c.5135C>T (p.Ala1712Val) missense substitution and the c.4478C>G (p.Ser1493*) nonsense substitution; in Family 2 were homozygous for the c.4478C>A (p.Ser1493*) nonsense substitution and in Family 3 were homozygous for the c.7518-1G>A (p.Trp2507Argfs*4) substitution. The severe developmental and epileptic encephalopathy manifested from the first day of life and was associated with deafness, mild peripheral polyneuropathy and …

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Dec 2019 • Journal of biophotonics

Contact‐free endoscopic photoacoustic sensing using speckle analysis

Benjamin Lengenfelder, Fanuel Mehari, Martin Hohmann, Cita Löhr, Maximilian J Waldner, Michael Schmidt, Zeev Zalevsky, Florian Klämpfl

Photoacoustic endoscopy (PAE) is an emerging imaging modality, which offers a high imaging penetration and a high optical contrast in soft tissue. Most of the developed endoscopic photoacoustic sensing systems use miniaturized contact ultrasound transducers or complex optical approaches. In this work, a new fiber‐based detection technique using speckle analysis for contact‐free signal detection is presented. Phantom and ex vivo experiments are performed in transmission and reflection mode for proof of concept. In summary, the potential of the technique for endoscopic photoacoustic signal detection is demonstrated. The new technique might help in future to broaden the applications of PAE in imaging or guiding minimally invasive laser procedures.

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Dec 2019 • International Journal of Mass Spectrometry

Chiral recognition via abundances of mixed chiral clusters

M Nihamkin, A Kaiser, I Nemtsov, P Martini, P Scheier, Y Mastai, Y Toker

When chiral molecules form clusters in the gas phase their abundance often exhibits pronounced chiral effects. In this work we pose the question of whether and how this phenomena can be used for chiral recognition: whether by mixing a solution of a test molecule of unknown enantiomeric excess with a known homochiral probe molecule and measuring the abundance of the mixed clusters one can determine the enantiomeric excess of the test molecule. Focusing on mixed amino acid clusters, we will show that the technique is not general, but for many cases is applicable. In doing so, systematic trends governing cluster formation have to be understood, and are discussed below.

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Dec 2019 • Nanomaterials

Antibacterial activity against methicillin-resistant staphylococcus aureus of colloidal polydopamine prepared by carbon dot stimulated polymerization of dopamine

Moorthy Maruthapandi, Michal Natan, Gila Jacobi, Ehud Banin, John HT Luong, Aharon Gedanken

A simple one-step process for the polymerization of dopamine has been developed using nitrogen-doped carbon dots ([email protected]–dots) as the sole initiator. The synthesized amorphous polydopamine (PDA)-doped [email protected]–dots (PDA–[email protected]–dots composite) exhibited a negative charge of–39 mV with particle sizes ranging from 200 to 1700 nm. The stable colloidal solution was active against methicillin-resistant Staphylococcus aureus (MRSA), a Gram-negative bacterium. The strong adhesion of the polymer to the bacterial membrane resulted in a limited diffusion of nutrients and wastes in and out of the cell cytosol, which is a generic mechanism to trigger cell death. Another possible route is the autoxidation of the catechol moiety of PDA to form quinone and release reactive oxygen species (ROS) such as superoxide radicle and hydrogen peroxide, two well-known ROS with antimicrobial properties against both Gram-negative and Gram-positive bacteria. View Full-Text

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Dec 2019 • Cell reports

SIRT6 promotes hepatic beta-oxidation via activation of PPARα

Shoshana Naiman, Frank K Huynh, Reuven Gil, Yair Glick, Yael Shahar, Noga Touitou, Liat Nahum, Matan Y Avivi, Asael Roichman, Yariv Kanfi, Asaf A Gertler, Tirza Doniger, Olga R Ilkayeva, Ifat Abramovich, Orly Yaron, Batia Lerrer, Eyal Gottlieb, Robert A Harris, Doron Gerber, Matthew D Hirschey, Haim Y Cohen

The pro-longevity enzyme SIRT6 regulates various metabolic pathways. Gene expression analyses in SIRT6 heterozygotic mice identify significant decreases in PPARα signaling, known to regulate multiple metabolic pathways. SIRT6 binds PPARα and its response element within promoter regions and activates gene transcription. Sirt6+/− results in significantly reduced PPARα-induced β-oxidation and its metabolites and reduced alanine and lactate levels, while inducing pyruvate oxidation. Reciprocally, starved SIRT6 transgenic mice show increased pyruvate, acetylcarnitine, and glycerol levels and significantly induce β-oxidation genes in a PPARα-dependent manner. Furthermore, SIRT6 mediates PPARα inhibition of SREBP-dependent cholesterol and triglyceride synthesis. Mechanistically, SIRT6 binds PPARα coactivator NCOA2 and decreases liver NCOA2 K780 acetylation, which stimulates its activation of …

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Dec 2019 • Journal of Low Temperature Physics

Niobium nitride thin films for very low temperature resistive thermometry

Tuyen Nguyen, Adib Tavakoli, Sebastien Triqueneaux, Rahul Swami, Aki Ruhtinas, Jeremy Gradel, Pablo Garcia-Campos, Klaus Hasselbach, Aviad Frydman, Benjamin Piot, Mathieu Gibert, Eddy Collin, Olivier Bourgeois

We investigate thin-film resistive thermometry based on metal-to-insulator transition (niobium nitride) materials down to very low temperature. The variation of the NbN thermometer resistance has been calibrated versus temperature and magnetic field. High sensitivity in temperature variation detection is demonstrated through efficient temperature coefficient of resistance. The nitrogen content of the niobium nitride thin films can be tuned to adjust the optimal working temperature range. In the present experiment, we show the versatility of the NbN thin-film technology through applications in very different low-temperature use cases. We demonstrate that thin-film resistive thermometry can be extended to temperatures below 30 mK with low electrical impedance.

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Dec 2019 • Carbon

Abnormal electrochemical behavior of rounded graphite

Ortal Lavi, Ortal Haik, Daniel Hirshberg, Yosef Talyosef, Ella Zinigard, Boris Markovsky, Yulia Vestfrid, Yuval Elias, Doron Aurbach, Daniela Kovacheva

Round-shaped natural graphite is commonly used as anode material for rechargeable lithium-ion batteries. We report atypical electrochemical behavior of round-shaped graphite anodes in Li-ion batteries: an intriguing phenomenon whereby substantial progressive increase in capacity is observed over tens of cycles. To understand the reasons underlying this abnormal behavior, we investigated the surface and bulk structure properties using HRSEM, XRD and Raman spectroscopy. Graphite particles with tense structure undergo exfoliation and fracture due to multiple transformations in intercalation/deintercalation processes. The increased capacity may result from enhanced particle exfoliation, compared with non-rounded graphite, which is accompanied by appearance of graphene sheets and fracture.

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Antibody repertoire sequencing and genomic DNA analysis reveal a large number of polymorphisms in the variable immunoglobulin genes

Ivana Mikocziova, Moriah Gidoni, Ida Lindeman, Omri Snir, Gur Yaari, Ludvig M Sollid

Dec 2019 • Journal of The Electrochemical Society

Corrosion resistance and acidic ORR activity of Pt-based catalysts supported on nanocrystalline alloys of molybdenum and tantalum carbide

Eliran R Hamo, Polina Tereshchuk, Melina Zysler, David Zitoun, Amir Natan, Brian A Rosen

Cathode catalysts in polymer electrolyte membrane fuel cells (PEMFCs) are often supported by carbon, which is susceptible to corrosion at operating potentials. Transition metal carbides (TMCs) are a class of material that could be used as catalyst supports to replace carbon as they are electrically conductive and can be resistant to corrosion. TMCs which show promising activity for the oxygen reduction reaction (ORR) have been shown to suffer from oxidation and dissolution, whereas corrosion-resistant carbides tend to have significantly lower ORR activities. Here we used co-reduction carburization to synthesized alloys of Mo 2 C and TaC with the aim of designing a carbide support that was both active and corrosion resistant. The addition of 15 mol% Ta to the precursor mixture used to synthesize the alloy support increased the corrosion potential by nearly 150 mV and decreased the corrosion current to 16% of …

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Dec 2019 • PloS one

Inhibiting the copper efflux system in microbes as a novel approach for developing antibiotics

Aviv Meir, Veronica Lepechkin-Zilbermintz, Shirin Kahremany, Fabian Schwerdtfeger, Lada Gevorkyan-Airapetov, Anna Munder, Olga Viskind, Arie Gruzman, Sharon Ruthstein

Five out of six people receive at least one antibiotic prescription per year. However, the ever-expanding use of antibiotics in medicine, agriculture, and food production has accelerated the evolution of antibiotic-resistant bacteria, which, in turn, made the development of novel antibiotics based on new molecular targets a priority in medicinal chemistry. One way of possibly combatting resistant bacterial infections is by inhibiting the copper transporters in prokaryotic cells. Copper is a key element within all living cells, but it can be toxic in excess. Both eukaryotic and prokaryotic cells have developed distinct copper regulation systems to prevent its toxicity. Therefore, selectively targeting the prokaryotic copper regulation system might be an initial step in developing next-generation antibiotics. One such system is the Gram-negative bacterial CusCFBA efflux system. CusB is a key protein in this system and was previously reported to play an important role in opening the channel for efflux via significant structural changes upon copper binding while also controlling the assembly and disassembly process of the entire channel. In this study, we aimed to develop novel peptide copper channel blockers, designed by in silico calculations based on the structure of CusB. Using a combination of magnetic resonance spectroscopy and various biochemical methods, we found a lead peptide that promotes copper-induced cell toxicity. Targeting copper transport in bacteria has not yet been pursued as an antibiotic mechanism of action. Thus, our study lays the foundation for discovering novel antibiotics.

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Dec 2019 • Nanomaterials

Advanced Surface Probing Using a Dual-Mode NSOM–AFM Silicon-Based Photosensor

Matityahu Karelits, Emanuel Lozitsky, Avraham Chelly, Zeev Zalevsky, Avi Karsenty

A feasibility analysis is performed for the development and integration of a near-field scanning optical microscope (NSOM) tip–photodetector operating in the visible wavelength domain of an atomic force microscope (AFM) cantilever, involving simulation, processing, and measurement. The new tip–photodetector consists of a platinum–silicon truncated conical photodetector sharing a subwavelength aperture, and processing uses advanced nanotechnology tools on a commercial silicon cantilever. Such a combined device enables a dual-mode usage of both AFM and NSOM measurements when collecting the reflected light directly from the scanned surface, while having a more efficient light collection process. In addition to its quite simple fabrication process, it is demonstrated that the AFM tip on which the photodetector is processed remains operational (ie, the AFM imaging capability is not altered by the process). The AFM–NSOM capability of the processed tip is presented, and preliminary results show that AFM capability is not significantly affected and there is an improvement in surface characterization in the scanning proof of concept. View Full-Text

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Dec 2019 • Angewandte Chemie International Edition

Heat‐Treated Aerogel as a Catalyst for Oxygen Reduction Reaction

Noam Zion, David A Cullen, Piotr Zelenay, Lior Elbaz

Aerogels are fascinating materials that can be used for a wide range of applications, one of which is electrocatalysis of the important oxygen reduction reaction. In their inorganic form, aerogels can have ultrahigh catalytic site density, high surface area, and tunable physical properties and chemical structures—important features in heterogeneous catalysis. Herein, we report on the synthesis and electrocatalytic properties of an iron–porphyrin aerogel. 5,10,15,20‐(Tetra‐4‐aminophenyl)porphyrin (H2TAPP) and FeII were used as building blocks of the aerogel, which was later heat‐treated at 600 °C to enhance electronic conductivity and catalytic activity, while preserving its macrostructure. The resulting material has a very high concentration of atomically dispersed catalytic sites (9.7×1020 sites g−1) capable of catalyzing the oxygen reduction reaction in alkaline solution (Eonset=0.92 V vs. RHE, TOF=0.25 e …

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Dec 2019 • Journal of nanobiotechnology

In vivo MRI assessment of bioactive magnetic iron oxide/human serum albumin nanoparticle delivery into the posterior segment of the eye in a rat model of retinal degeneration

Adi Tzameret, Hadas Ketter-Katz, Victoria Edelshtain, Ifat Sher, Enav Corem-Salkmon, Itay Levy, David Last, David Guez, Yael Mardor, Shlomo Margel, Ygal Rotenstrich

Retinal degeneration diseases affect millions of patients worldwide and lead to incurable vision loss. These diseases are caused by pathologies in the retina and underlying choroid, located in the back of the eye. One of the major challenges in the development of treatments for these blinding diseases is the safe and efficient delivery of therapeutics into the back of the eye. Previous studies demonstrated that narrow size distribution core–shell near infra-red fluorescent iron oxide (IO) nanoparticles (NPs) coated with human serum albumin (HSA, IO/HSA NPs) increase the half-life of conjugated therapeutic factors, suggesting they may be used for sustained release of therapeutics. In the present study, the in vivo tracking by MRI and the long term safety of IO/HSA NPs delivery into the suprachoroid of a rat model of retinal degeneration were assessed. Twenty-five Royal College of Surgeons (RCS) pigmented rats …

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Dec 2019 • Physical Review Research

Transport in disordered systems: the single big jump approach

Wanli Wang, Alessandro Vezzani, Raffaella Burioni, Eli Barkai

In a growing number of strongly disordered and dense systems, the dynamics of a particle pulled by an external force field exhibits superdiffusion. In the context of glass-forming systems, supercooled glasses, and contamination spreading in porous media, it was suggested that this behavior be modeled with a biased continuous-time random walk. Here we analyze the plume of particles lagging far behind the mean, with the single big jump principle. Revealing the mechanism of the anomaly, we show how a single trapping time, the largest one, is responsible for the rare fluctuations in the system. These nontypical fluctuations still control the behavior of the mean square displacement, which is the most basic quantifier of the dynamics in many experimental setups. We show how the initial conditions, describing either the stationary state or nonequilibrium case, persist forever in the sense that the rare fluctuations are …

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