BINA

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.

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 …

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 …

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.

The goal of the experiment was to investigate higher-order X-ray-optical sum-frequency generation (XSFG) as a means to study the dynamics of linear and nonlinear optically-induced local polarization effects in solids with Angstrom resolution. XSFG can be used as time-resolved atomic-scale probe of the dynamics of optically induced charge densities. The ability to optically control carrier dynamics in samples at the microscopic scale has the potential to become the basis of ultrafast optical switching of currents and future petahertz optoelectronic devices.

Stress granules (SGs) can assemble in cancer cells upon chemotoxic stress. Glucocorticoids function during stress responses and are administered with chemotherapies. The roles of glucocorticoids in SG assembly and disassembly pathways are unknown. We examined whether combining glucocorticoids such as cortisone with chemotherapies from the vinca alkaloid family, which dismantle the microtubule network, affects SG assembly and disassembly pathways and influences cell viability in cancer cells and human-derived organoids. Cortisone augmented SG formation when combined with vinorelbine (VRB). Live-cell imaging showed that cortisone increased SG assembly rates but reduced SG clearance rates after stress, by increasing protein residence times within the SGs. Mechanistically, VRB and cortisone signaled through the integrated stress response mediated by eIF2α (also known as EIF2S1 …

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.

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 …

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.

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 …

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.

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 …

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.

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 …

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 …

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 …

Carbon aerogels have been studied in the context of fuel cell electrodes mainly as catalyst support materials due to their high surface area, porosity, and electrical conductivity. Recently, aerogels composed solely of inorganic molecular complexes have shown to be promising materials for the electrocatalysis of oxygen reduction reaction (ORR). These aerogels consist of atomically dispersed catalytic sites. Herein, we report on the synthesis and characterization of an aerogel-based catalyst: iron phthalocyanine aerogel. It was synthesized by coupling of ethynyl-terminated phthalocyanine monomers and then heat-treated at 800 °C to increase its electrical conductivity and catalytic activity. The aerogels reported here were tested as catalysts for ORR in acidic conditions for the first time and found to have a ultra-high number of atomically dispersed catalytic sites (7.11 × 1020 sites g–1) and very good catalytic activity (E …

Variation of grating amplitudes on a surface of amorphous chalcogenide films (ACF) As20Se80 has been studied under illumination by a band-gap light with the purpose to understand mechanism of photo-induced (PI) mass transfer. After holographic recording of surface relief gratings (SRGs) of various periods Λ (from 3 to 15 µm) they were illuminated by a diode laser (λ = 660 nm) and their profile variation was analyzed using optical microscopy, atomic force microscopy, light scattering, and optical profilometry. The SRGs with Λ < 8 µm exponentially flattened with time of illumination, whereas amplitudes of the SRGs with Λ > 8 µm exponentially grew. Theoretical analysis of the kinetics of PI mass transfer shows that the SRG profile variation occurs by bulk diffusion of As and Se atoms as a result of competition between capillary forces and electrostatic forces created by redistribution of electrons and holes generated …