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Aug 2022 • ACS Applied Bio Materials

Cuprous Oxide Nanoparticles Decorated Fabric Materials with Anti-biofilm Properties

Akanksha Gupta, Moorthy Maruthapandi, Poushali Das, Arumugam Saravanan, Gila Jacobi, Michal Natan, Ehud Banin, John HT Luong, Aharon Gedanken

Considering the global spread of bacterial infections, the development of anti-biofilm surfaces with high antimicrobial activities is highly desired. This work unraveled a simple, sonochemical method for coating Cu2O nanoparticles (NPs) on three different flexible substrates: polyester (PE), nylon 2 (N2), and polyethylene (PEL). The introduction of Cu2O NPs on these substrates enhanced their surface hydrophobicity, induced ROS generation, and completely inhibited the growth of sensitive (Escherichia coli and Staphyloccocus aureus) and drug-resistant (MDR E. coli and MRSA) planktonic and biofilm. The experimental results confirmed that Cu2O-PE exhibited complete biofilm mass reduction ability for all four strains, whereas Cu2O-N2 showed more than 99% biomass inhibition against both drug-resistant and sensitive pathogens in 6 h. Moreover, Cu2O-PEL also indicated a 99.95, 97.73, 98.00, and 99.20 …

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Aug 2022 • Journal of Chemical Theory and Computation

Solvent Dependent Nuclear Magnetic Resonance Molecular Parameters Based on a Polarization Consistent Screened Range Separated Hybrid Density Functional Theory Framework

Khadiza Begam, Lilian Cohen, Gil Goobes, Barry D Dunietz

Nuclear magnetic resonance (NMR) properties of solvated molecules are significantly affected by the solvent. We, therefore, employ a polarization consistent framework that efficiently addresses the solvent polarizing environment effects. Toward this goal a dielectric screened range separated hybrid (SRSH) functional is invoked with a polarizable continuum model (PCM) to properly represent the orbital gap in the condensed phase. We build on the success of range separated hybrid (RSH) functionals to address the erroneous tendency of traditional density functional theory (DFT) to collapse the orbital gap. Recently, the impact of RSH that properly opens up the orbital gap in gas-phase calculations on NMR properties has been assessed. Here, we report the use of SRSH-PCM that produces properly solute orbital gaps in calculating isotropic nuclear magnetic shielding and chemical shift parameters of molecular …

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Aug 2022 • Catalysts 12 (8), 909, 2022

Levulinic Acid Is a Key Strategic Chemical from Biomass

Amudhavalli Victor, Pankaj Sharma, Indra Neel Pulidindi, Aharon Gedanken

Levulinic acid (LA) is one of the top twelve chemicals listed by the US Department of Energy that can be derived from biomass. It serves as a building block and platform chemical for producing a variety of chemicals, fuels and materials which are currently produced in fossil based refineries. LA is a key strategic chemical, as fuel grade chemicals and plastic substitutes can be produced by its catalytic conversion. LA derivatisation to various product streams, such as alkyl levulinates via esterification, γ-valerolactone via hydrogenation and N-substituted pyrrolidones via reductive amination and many other transformations of commercial utility are possible owing to the two oxygen functionalities, namely, carbonyl and carboxyl groups, present within the same substrate. Various biomass feedstock, such as agricultural wastes, marine macroalgae, and fresh water microalgae were successfully converted to LA in high yields. Finding a substitute to mineral acid catalysts for the conversion of biomass to LA is a challenge. The use of an ultrasound technique facilitated the production of promising nano-solid acid catalysts including Ga salt of molybophosphoric acid and Ga deposited mordenite zeolite, with optimum amounts of Lewis and Bronsted acidities needed for the conversion of glucose to LA in high yields, being 56 and 59.9 wt.% respectively. Microwave irradiation technology was successfully utilized for the accelerated production of LA (53 wt.%) from glucose in a short duration of 6 min, making use of the unique synergistic catalytic activity of ZnBr 2 and HCl. View Full-Text

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Aug 2022 • ACS Applied Bio Materials

Cuprous oxide nanoparticles decorated fabric materials with anti-biofilm properties

Akanksha Gupta, Moorthy Maruthapandi, Poushali Das, Arumugam Saravanan, Gila Jacobi, Michal Natan, Ehud Banin, John HT Luong, Aharon Gedanken

Considering the global spread of bacterial infections, the development of anti-biofilm surfaces with high antimicrobial activities is highly desired. This work unraveled a simple, sonochemical method for coating Cu2O nanoparticles (NPs) on three different flexible substrates: polyester (PE), nylon 2 (N2), and polyethylene (PEL). The introduction of Cu2O NPs on these substrates enhanced their surface hydrophobicity, induced ROS generation, and completely inhibited the growth of sensitive (Escherichia coli and Staphyloccocus aureus) and drug-resistant (MDR E. coli and MRSA) planktonic and biofilm. The experimental results confirmed that Cu2O-PE exhibited complete biofilm mass reduction ability for all four strains, whereas Cu2O-N2 showed more than 99% biomass inhibition against both drug-resistant and sensitive pathogens in 6 h. Moreover, Cu2O-PEL also indicated a 99.95, 97.73, 98.00, and 99.20 …

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Aug 2022 • Physical Review Letters

Discrete sampling of extreme events modifies their statistics

Lior Zarfaty, Eli Barkai, David A Kessler

Extreme value (EV) statistics of correlated systems are widely investigated in many fields, spanning the spectrum from weather forecasting to earthquake prediction. Does the unavoidable discrete sampling of a continuous correlated stochastic process change its EV distribution? We explore this question for correlated random variables modeled via Langevin dynamics for a particle in a potential field. For potentials growing at infinity faster than linearly and for long measurement times, we find that the EV distribution of the discretely sampled process diverges from that of the full continuous dataset and converges to that of independent and identically distributed random variables drawn from the process’s equilibrium measure. However, for processes with sublinear potentials, the long-time limit is the EV statistics of the continuously sampled data. We treat processes whose equilibrium measures belong to the three EV …

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Aug 2022 • Proceedings of the National Academy of Sciences

The Role of Spin-Flip Collisions in a Dark-Exciton Condensate

Subhradeep Misra, Michael Stern, Vladimir Umansky, Israel Bar-Joseph

We show that a Bose–Einstein condensate consisting of dark excitons forms in GaAs coupled quantum wells at low temperatures. We find that the condensate extends over hundreds of micrometers, well beyond the optical excitation region, and is limited only by the boundaries of the mesa. We show that the condensate density is determined by spin-flipping collisions among the excitons, which convert dark excitons into bright ones. The suppression of this process at low temperature yields a density buildup, manifested as a temperature-dependent blueshift of the exciton emission line. Measurements under an in-plane magnetic field allow us to preferentially modify the bright exciton density and determine their role in the system dynamics. We find that their interaction with the condensate leads to its depletion. We present a simple rate-equations model, which well reproduces the observed temperature, power, and …

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Aug 2022 • Advanced Functional Materials

Operating Highly Stable LiCoO2 Cathodes up to 4.6 V by Using an Effective Integration of Surface Engineering and Electrolyte Solutions Selection

Tianju Fan, Wang Kai, Villa Krishna Harika, Cunsheng Liu, Amey Nimkar, Nicole Leifer, Sandipan Maiti, Judith Grinblat, Merav Nadav Tsubery, Xiaolang Liu, Meng Wang, Leimin Xu, Yuhao Lu, Yonggang Min, Netanel Shpigel, Doron Aurbach

The need for high power density cathodes for Li‐ion batteries can be fulfilled by application of a high charging voltage above 4.5 V. As lithium cobalt oxide (LCO) remains a dominant commercial cathode material, tremendous efforts are invested to increase its charging potential toward 4.6 V. Yet, the long‐term performance of high voltage LCO cathodes still remains poor. Here, an integrated approach combining the application of an aluminum fluoride coating and the use of electrolyte solutions comprising 1:1:8 mixtures of difluoroethylene:fluoroethylene carbonate:dimethyl carbonate and 1 m LiPF6 is reported. This results in superior behavior of LCO cathodes charged at 4.6 V with high initial capacity of 223 mAh g−1, excellent long‐term performance, and 78% capacity retention after 500 cycles. Impressive stability is also found at 450 °C with an initial capacity of 220 mAh g−1 and around 84% capacity retention …

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Aug 2022 • Physical Review Letters

Discrete sampling of extreme events modifies their statistics

Lior Zarfaty, Eli Barkai, David A Kessler

Extreme value (EV) statistics of correlated systems are widely investigated in many fields, spanning the spectrum from weather forecasting to earthquake prediction. Does the unavoidable discrete sampling of a continuous correlated stochastic process change its EV distribution? We explore this question for correlated random variables modeled via Langevin dynamics for a particle in a potential field. For potentials growing at infinity faster than linearly and for long measurement times, we find that the EV distribution of the discretely sampled process diverges from that of the full continuous dataset and converges to that of independent and identically distributed random variables drawn from the process’s equilibrium measure. However, for processes with sublinear potentials, the long-time limit is the EV statistics of the continuously sampled data. We treat processes whose equilibrium measures belong to the three EV …

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Aug 2022 • Optical Fiber Sensors, Tu1. 4, 2022

Brillouin optical time-domain distributed analysis of cladding modes in a coated fiber

Elad Zehavi, Alon Bernstein, Gil Bashan, Yosef London, Hilel Hagai Diamandi, Kavita Sharma, Mirit Hen, A Zadok

Brillouin optical time domain analysis of coupling to cladding modes of standard, coated fiber is demonstrated. Uncertainty in local changes of effective indices is below 10-6 RIU. Local effect of acetone on coating is identified.

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Aug 2022 • Optica 9 (3), 273-279, 2022

Quasi-static optical parametric amplification

Marc Jankowski, Nayara Jornod, Carsten Langrock, Boris Desiatov, Alireza Marandi, Marko Lončar, Martin M Fejer

We use dispersion-engineered PPLN nanowaveguides to demonstrate opti-cal parametric amplification without either temporal walk-off or group velocity dispersion. These quasi-static devices achieve large gains (> 145 dB/cm) across> 900 nanometers using picojoules of pump pulse energy.

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Jul 2022 • ACS APPLIED NANO MATERIALS

Co3O4 vertical bar CoP Core-Shell Nanoparticles with Enhanced Electrocatalytic Water Oxidation Performance

Bibhudatta Malik, Hari Krishna Sadhanala, Rong Sun, Francis Leonard Deepak, Aharon Gedanken, Gilbert Daniel Nessim

Developing high performance, cost-effective, and durable electrocatalysts that must be derived from non-noble metals is crucial for alkaline oxygen evolution reaction (OER). OER, which takes place at the anode, is accepted as a major obstacle for commercialization due to its sluggish kinetics. In this study, a two-step synthesis method, such as a hydrothermal process followed by the annealing of the reactants in an Ar-filled Swagelok cell, is briefly described to obtain a cubic type of Co3O4 core and CoP shell. As a result of synergy, Co3O4 vertical bar CoP demonstrates an onset overpotential of 280 mV and reaches a current density of 10 mA cm(-2) at an overpotential of 320 mV in an alkaline medium (pH = 13.5). The electronic property of the heterojunction is verified by the Tauc plot and valence band XPS. The band structure indicates that Co3O4 vertical bar CoP exhibits a more metallic character than pristine …

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Jul 2022 • Journal of cell science 135 (13), jcs259594, 2022

Nuclear speckles–a driving force in gene expression

Gabriel P Faber, Shani Nadav-Eliyahu, Yaron Shav-Tal

Nuclear speckles are dynamic membraneless bodies located in the cell nucleus. They harbor RNAs and proteins, many of which are splicing factors, that together display complex biophysical properties dictating nuclear speckle formation and maintenance. Although these nuclear bodies were discovered decades ago, only recently has in-depth genomic analysis begun to unravel their essential functions in modulation of gene activity. Major advancements in genomic mapping techniques combined with microscopy approaches have enabled insights into the roles nuclear speckles may play in enhancing gene expression, and how gene positioning to specific nuclear landmarks can regulate gene expression and RNA processing. Some studies have drawn a link between nuclear speckles and disease. Certain maladies either involve nuclear speckles directly or dictate the localization and reorganization of many nuclear speckle factors. This is most striking during viral infection, as viruses alter the entire nuclear architecture and highjack host machinery. As discussed in this Review, nuclear speckles represent a fascinating target of study not only to reveal the links between gene positioning, genome subcompartments and gene activity, but also as a potential target for therapeutics.

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Jul 2022 • Nature

Magnetic memory and spontaneous vortices in a van der Waals superconductor

Eylon Persky, Anders V Bjørlig, Irena Feldman, Avior Almoalem, Ehud Altman, Erez Berg, Itamar Kimchi, Jonathan Ruhman, Amit Kanigel, Beena Kalisky

Doped Mott insulators exhibit some of the most intriguing quantum phases of matter, including quantum spin liquids, unconventional superconductors and non-Fermi liquid metals–. Such phases often arise when itinerant electrons are close to a Mott insulating state, and thus experience strong spatial correlations. Proximity between different layers of van der Waals heterostructures naturally realizes a platform for experimentally studying the relationship between localized, correlated electrons and itinerant electrons. Here we explore this relationship by studying the magnetic landscape of tantalum disulfide 4Hb-TaS2, which realizes an alternating stacking of a candidate spin liquid and a superconductor. We report on a spontaneous vortex phase whose vortex density can be trained in the normal state. We show that time-reversal symmetry is broken in the normal state, indicating the presence of a magnetic phase …

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Jul 2022 • Physical Review Applied

Tunable superconducting flux qubits with long coherence times

T Chang, T Cohen, I Holzman, G Catelani, M Stern

In this work, we study a series of tunable flux qubits inductively coupled to a coplanar waveguide resonator fabricated on a sapphire substrate. Each qubit includes an asymmetric superconducting quantum interference device, which is controlled by the application of an external magnetic field and acts as a tunable Josephson junction. The tunability of the qubits is typically±3.5 GHz around their central gap frequency. The measured relaxation times are limited by dielectric losses in the substrate and can attain T 1∼ 8 μ s. The echo dephasing times are limited by flux noise even at optimal points and reach T 2 E∼ 4 μ s, almost an order of magnitude longer than state of the art.

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Jul 2022 • Journal of Solid State Electrochemistry 26 (9), 1839-1850, 2022

Assessing and measuring the active site density of PGM-free ORR catalysts

Rifael Z Snitkoff-Sol, Lior Elbaz

Fuel cells are already employed in commercial transportation even though their price is still too high to enable widespread production. A viable and promising pathway taken to lower this price is the replacement of expensive constitutes, namely the platinum-based catalysts at the cathode, by platinum group metal-free catalysts based on abundant materials, such as iron. This led to the development of iron-based catalysts that show high activity towards the oxygen reduction reaction. The extraction of the intrinsic catalytic activity of any catalyst is important both for finding relations between the chemical properties of the active sites and their activity, as well as a comparison measure between catalysts. An important parameter that has been elusive for many years is the turnover frequency, which is derived form the number of electrochemical active sites’ density (EASD). The ability to measure the EASD was very limited …

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Jul 2022 • ACS Applied Electronic Materials

Current Mapping of Amorphous LaAlO3/SrTiO3 near the Metal–Insulator Transition

Anders V Bjørlig, Dennis V Christensen, Ricci Erlandsen, Nini Pryds, Beena Kalisky

The two-dimensional electron system found between LaAlO3 and SrTiO3 hosts a variety of physical phenomena that can be tuned through external stimuli. This allows for electronic devices controlling magnetism, spin–orbit coupling, and superconductivity. Controlling the electron density by varying donor concentrations and using electrostatic gating are convenient handles to modify the electronic properties, but the impact on the microscopic scale, particularly of the former, remains underexplored. Here, we image the current distribution at 4.2 K in amorphous-LaAlO3/SrTiO3 using scanning superconducting quantum interference device microscopy while changing the carrier density in situ using electrostatic gating and oxygen annealing. We show how potential disorder affects the current and how homogeneous 2D flow evolves into several parallel conducting channels when approaching the metal-to-insulator …

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Jul 2022 • arXiv preprint arXiv:2207.01460

Tunable superconducting flux qubits with long coherence times

T Chang, T Cohen, I Holzman, G Catelani, M Stern


Jul 2022 • arXiv preprint arXiv:2207.01427

Reproducibility and control of superconducting flux qubits

T Chang, I Holzman, T Cohen, BC Johnson, DN Jamieson, M Stern

Superconducting flux qubits are promising candidates for the physical realization of a scalable quantum processor. Indeed, these circuits may have both a small decoherence rate and a large anharmonicity. These properties enable the application of fast quantum gates with high fidelity and reduce scaling limitations due to frequency crowding. The major difficulty of flux qubits' design consists of controlling precisely their transition energy - the so-called qubit gap - while keeping long and reproducible relaxation times. Solving this problem is challenging and requires extremely good control of e-beam lithography, oxidation parameters of the junctions and sample surface. Here we present measurements of a large batch of flux qubits and demonstrate a high level of reproducibility and control of qubit gaps, relaxation times and pure echo dephasing times. These results open the way for potential applications in the fields of quantum hybrid circuits and quantum computation.

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Jul 2022 • arXiv preprint arXiv:2207.01669

Interdependent superconducting networks

I Bonamassa, B Gross, M Laav, I Volotsenko, A Frydman, S Havlin

Cascades are self-amplifying processes triggered by feedback mechanisms that may cause a substantial part of a macroscopic system to change its phase in response of a relatively small local event. The theoretical background for these phenomena is rich and interdisciplinary with interdependent networks providing a versatile "two-interactions" framework to study their multiscale evolution. Yet, physics experiments aimed at validating this ever-growing volume of predictions have remained elusive, hitherto hindered by the problem of identifying possible physical mechanisms realizing interdependent couplings. Here we develop and study the first experimental realization of an interdependent system as a multilayer network of two disordered superconductors separated by an insulating film. We show that Joule heating effects emerging at sufficiently large driving currents act as dependency links between the superconducting layers, igniting overheating cascades via adaptive back and forth electro-thermal feedbacks. Through theory and experiments, we unveil a rich phase diagram of mutual resistive transitions and cascading processes that physically realize and generalize interdependent percolation. The present work establishes the first physics laboratory bench for the manifestation of the theory of interdependent systems, enabling experimental studies to control and to further develop the multilayer phenomena of complex interdependent materials.

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Jul 2022 • ACS Applied Nano Materials

Co3O4|CoP Core–Shell Nanoparticles with Enhanced Electrocatalytic Water Oxidation Performance

Bibhudatta Malik, Hari Krishna Sadhanala, Rong Sun, Francis Leonard Deepak, Aharon Gedanken, Gilbert Daniel Nessim

Developing high performance, cost-effective, and durable electrocatalysts that must be derived from non-noble metals is crucial for alkaline oxygen evolution reaction (OER). OER, which takes place at the anode, is accepted as a major obstacle for commercialization due to its sluggish kinetics. In this study, a two-step synthesis method, such as a hydrothermal process followed by the annealing of the reactants in an Ar-filled Swagelok cell, is briefly described to obtain a cubic type of Co3O4 core and CoP shell. As a result of synergy, Co3O4|CoP demonstrates an onset overpotential of 280 mV and reaches a current density of 10 mA cm–2 at an overpotential of 320 mV in an alkaline medium (pH = 13.5). The electronic property of the heterojunction is verified by the Tauc plot and valence band XPS. The band structure indicates that Co3O4|CoP exhibits a more metallic character than pristine Co3O4 due to the fact that …

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Jul 2022 • ACS Applied Nano Materials

Co3O4|CoP Core–Shell Nanoparticles with Enhanced Electrocatalytic Water Oxidation Performance

Bibhudatta Malik, Hari Krishna Sadhanala, Rong Sun, Francis Leonard Deepak, Aharon Gedanken, Gilbert Daniel Nessim

Developing high performance, cost-effective, and durable electrocatalysts that must be derived from non-noble metals is crucial for alkaline oxygen evolution reaction (OER). OER, which takes place at the anode, is accepted as a major obstacle for commercialization due to its sluggish kinetics. In this study, a two-step synthesis method, such as a hydrothermal process followed by the annealing of the reactants in an Ar-filled Swagelok cell, is briefly described to obtain a cubic type of Co3O4 core and CoP shell. As a result of synergy, Co3O4|CoP demonstrates an onset overpotential of 280 mV and reaches a current density of 10 mA cm–2 at an overpotential of 320 mV in an alkaline medium (pH = 13.5). The electronic property of the heterojunction is verified by the Tauc plot and valence band XPS. The band structure indicates that Co3O4|CoP exhibits a more metallic character than pristine Co3O4 due to the fact that …

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