BINA

Broad area laser diodes are attractive for the high optical power they can produce. Unfortunately, this high power normally comes at the cost of severely reduced spatial coherence since the wide area of the diode wave-guide is inherently spatially multi-mode along the slow axis. We demonstrate a method to significantly improve the spatial coherence of a high-power broad-area diode by placing it in an external cavity that is mode selective. We design the cavity, such that the diode aperture acts as its own spatial filter, obviating the need for an intra-cavity slit-filter, and optimally utilizing the entire gain medium. We demonstrate this soft filtering method using wide diodes of and widths and compare its power-efficiency to the standard approach of hard-filtering with a slit. We obtain high-gain operation in a pure single-mode, demonstrating up to 1.5 W CW power at 1064 nm with excellent beam quality …

In this work, we demonstrate the focusing of a Gaussian laser beam, in silicon, by a vortex-shaped beam where both beams are at a wavelength of 775nm, which can sharpen the beam's PSF to improve the resolution in laser scanning microscopy.

Neuroblastoma is a lethal childhood solid tumor of developing peripheral nerves. Two percent of children with neuroblastoma develop opsoclonus myoclonus ataxia syndrome (OMAS), a paraneoplastic disease characterized by cerebellar and brainstem-directed autoimmunity but typically with outstanding cancer-related outcomes. We compared tumor transcriptomes and tumor-infiltrating T and B cell repertoires from 38 OMAS subjects with neuroblastoma to 26 non-OMAS-associated neuroblastomas. We found greater B and T cell infiltration in OMAS-associated tumors compared to controls and showed that both were polyclonal expansions. Tertiary lymphoid structures (TLSs) were enriched in OMAS-associated tumors. We identified significant enrichment of the major histocompatibility complex (MHC) class II allele HLA-DOB∗01:01 in OMAS patients. OMAS severity scores were associated with the expression of …

The purpose of the review is to provide new insight into the potential of surface modification of carbon fibers for enhancing the application of the carbon fibers many a fold. To this end a total of 429 papers on the subject of surface modication of carbon fibers by a variety of chemical and electrochemical methods published during the period from 2010-2022 have been reviewed. Astounding results of surface funcationalization of carbon fibers by a variety of state of the art methods resulting in the unconventional applications of the resulting modified carbon fibers are summarized in a nut-shell in schemes from 1-6 towards the end of the review. Surface modifica-tion induces functionality to carbon fibers (CFs). The vitality of CF surface modification reac-tions could only be compared to the life process of respiration that sustains the multi functional-ity of living cells. Applicability of CFs can be drastically enhanced in incomprehensible ways by surface modification. Upon surface modification, inert and non-reactive CF surface becomes chemically active and functional with utility in diverse fields, namely, health, energy, environ-ment, defense, catalysis, smart materials and many others. Surface modification methods can be broadly classified into chemical, electrochemical and physical methods. By these surface modi-fication methods, the inert FC surface becomes polar. Surface properties like roughness, wetta-bility and energy are enhanced. Modification processes like sizing, oxidation, amination, si-lanization, polymerization, nanoarchitecture induces multifunctionality on CF surface. Modi-fied CFs when used as reinforcing material in carbon fiber …

Nanoporous gold (Au) films are self-supported structures that possess a large surface area and extraordinary catalytic activity. Generally, nanoporous gold is obtained by solution-based dealloying where the less noble metal, often silver (Ag), is etched out. However, the residual amounts of the sacrificial metal are not well controlled, the impure samples show restructuring, and the residual metal prevents the study of the catalytic role of Au alone. Here, we fabricate impurity-free nanoporous gold films by a plasma-enabled dry synthetic route. The scheme does not include sacrificial metals or solution processing and is much more general. It is used to obtain self-supported ultra-pure nanoporous gold films with controllable pore sizes. The impurity-free nanoporous gold films possess highly curved ligaments, are remarkably robust, and stable over hundreds of electrochemical cycles. Furthermore, they contain many …

BackgroundTissue-integrated micro-electronic devices for neural stimulation hold great potential in restoring the functionality of degenerated organs, specifically, retinal prostheses, which are aimed at vision restoration. The fabrication process of 3D polymer-metal devices with high resolution and a high aspect-ratio (AR) is very complex and faces many challenges that impair its functionality.ApproachHere we describe the optimization of the fabrication process of a bio-functionalized 3D high-resolution 1mm circular subretinal implant composed of SU-8 polymer integrated with dense gold microelectrodes (23μm pitch) passivated with 3D micro-well-like structures (20μm diameter, 3μm resolution). The main challenges were overcome by step-by-step planning and optimization while utilizing a two-step bi-layer lift-off process; bio-functionalization was carried out by N2 plasma treatment and the addition of a bio …

Thermal effects are well known to influence the electronic and optical properties of materials through several physical mechanisms and are the basis for various optoelectronic devices. The thermo-optic (TO) effect, the refractive index variation with temperature (dn/dT), is one of the most common mechanisms used for tunable optical devices, including integrated optical components, metasurfaces, and nano-antennas. However, when a static and fixed operation is required, i.e., temperature invariant performance – this effect becomes a drawback and may lead to undesirable behavior through drifting of the resonance frequency, amplitude, or phase, as the operating temperature varies over time. In this work, we present a systematic approach to mitigate thermally induced optical fluctuations in nanophotonic devices. By using hybrid subwavelength resonators composed from two materials with opposite TO dispersions …

Broad area laser diodes are attractive for the high optical power they can produce. Unfortunately, this high power normally comes at the cost of severely reduced spatial coherence since the wide area of the diode wave-guide is inherently spatially multi-mode along the slow axis. We demonstrate a method to significantly improve the spatial coherence of a high-power broad-area diode by placing it in an external cavity that is mode selective. We design the cavity, such that the diode aperture acts as its own spatial filter, obviating the need for an intra-cavity slit-filter, and optimally utilizing the entire gain medium. We demonstrate this soft filtering method using wide diodes of and widths and compare its power-efficiency to the standard approach of hard-filtering with a slit. We obtain high-gain operation in a pure single-mode, demonstrating up to 1.5 W CW power at 1064 nm with excellent beam quality …

Traumatic brain injury (TBI), which is characterized by damage to the brain resulting from a sudden traumatic event, is a major cause of death and disability worldwide. It has short- and long-term effects, including neuroinflammation, cognitive deficits, and depression. TBI consists of multiple steps that may sometimes have opposing effects or mechanisms, making it challenging to investigate and translate new knowledge into effective therapies. In order to better understand and address the underlying mechanisms of TBI, we have developed an in vitro platform that allows dynamic simulation of TBI conditions by applying external magnetic forces to induce acceleration and deceleration injury, which is often observed in human TBI. Endothelial and neuron-like cells were successfully grown on magnetic gels and applied to the platform. Both cell types showed an instant response to the TBI model, but the endothelial cells …

SignificanceDiabetes is a prevalent disease worldwide that can cause severe health problems. Accurate blood glucose detection is crucial for diabetes management, and noninvasive methods can be more convenient and less painful than traditional finger-prick methods.AimWe aim to report a noncontact speckle-based blood glucose measurement system that utilizes artificial intelligence (AI) data processing to improve glucose detection accuracy. The study also explores the influence of an alternating current (AC) induced magnetic field on the sensitivity and selectivity of blood glucose detection.ApproachThe proposed blood glucose sensor consists of a digital camera, an AC-generated magnetic field source, a laser illuminating the subject’s finger, and a computer. A magnetic field is applied to the finger, and a camera records the speckle patterns generated by the laser light reflected from the finger. The acquired …

Recent research on two-dimensional (2D) transition metal dichalcogenides (TMDCs) has led to remarkable discoveries of fundamental phenomena and to device applications with technological potential. Large-scale TMDCs grown by chemical vapor deposition (CVD) are now available at continuously improving quality, but native defects and natural degradation in these materials still present significant challenges. Spectral hysteresis in gate-biased photoluminescence (PL) measurements of WSe2 further revealed long-term trapping issues of charge carriers in intrinsic defect states. To address these issues, we apply here a two-step treatment with organic molecules, demonstrating the “healing” of native defects in CVD-grown WSe2 and WS2 by substituting atomic sulfur into chalcogen vacancies. We uncover that the adsorption of thiols provides only partial defect passivation, even for high adsorption quality, and …

The development of bioinspired catalysts for oxygen reduction reaction is one of the most prominent pathways in the search for active materials to replace Pt-based catalysts in fuel cells. Herein, we report innovative bioinspired catalysts using a directed synthetic pathway to create adjacent Cu and Fe sites. This catalyst is composed of a covalent 3D framework in an aerogel form. Aerogels are high surface area and porous hierarchical structures that can allow the formation of ultrahigh active site density and optimized mass transport of reactants and products to and from the catalytic sites. The aerogel-based catalyst exhibits high performance in a half-cell in 0.1 M KOH, with an onset potential of 0.94 V vs RHE and half-wave potential of E1/2 = 0.80 V vs RHE, high selectivity toward the four-electron reduction of oxygen to hydroxide anions, and high durability. These results are well-translated to the anion exchange …

Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society. However, the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction (HER) occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed. Therefore, efficient platinum group metals (PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded. In this scenario, molybdenum disulfide (MoS2) owing to efficacious structural attributes and optimum hydrogen-binding free energy (ΔGH*) is emerging as a reliable alternative to PGMs. However, the performance of MoS2-based electrocatalysts is still far away from the benchmark performance. The HER activity of MoS2 can be improved by engineering the structural parameters i.e., doping, defects inducement, modulating …

Na‐ion batteries have recently emerged as a promising alternative to Li‐based batteries, driven by an ever‐growing demand for electricity storage systems. In the present work, we propose a cobalt‐free high‐capacity cathode for Na‐ion batteries, synthesized using a high‐entropy approach. The high‐entropy approach entails mixing more than five elements in a single phase; hence, obtaining the desired properties is a challenge since this involves the interplay between different elements. Here, instead of oxide, oxyfluoride is chosen to suppress oxygen loss during long‐term cycling. Supplement to this, Li was introduced in the composition to obtain high configurational entropy and Na vacant sites, thus stabilizing the crystal structure, accelerating the kinetics of intercalation/deintercalation, and improving the air stability of the material. With the optimization of the cathode composition, a reversible capacity of 109 …

We present an experimental study on a terahertz quantum cascade laser (THz QCL) design that combines both two-well injector and directphonon scattering schemes, ie, a so-called two-well injector direct-phonon design. As a result of the two-well injector direct-phonon scheme presented here, the lasers benefit from both a direct phonon scattering scheme for the lower laser level depopulation and a setback for the doping profile that reduces the overlap of the doped region with active laser states. Additionally, our design also has efficient isolation of the active laser levels from excited and continuum states as indicated by negative differential resistance behavior all the way up to room temperature. This scheme serves as a good platform for improving the temperature performance of THz QCLs as indicated by the encouraging temperature performance results of the device with a relatively high doping level of 7.56 Â …

Efimov states are exotic and counterintuitive three-body quantum states that emerge in the vicinity of two-atom Feshbach resonances. These states exhibit remarkable characteristics as their large spatial extent and extremely weak binding energies following an infinite geometric series, and exist even when interactions are not strong enough to bind two atoms. Efimov states are universal and produce observable effects at critical values of the interaction strength across the two-body resonance when approaching their threshold for dissociation into the different types of three-body continua. In particular, as the strength of the interaction is decreased, an Efimov state merges into the atom-dimer threshold and eventually dissociates into an unbound atom-dimer pair. Here we explore this critical point using refined coherent few-body spectroscopy in Li atoms near a narrow two-body Feshbach resonance. Contrary to the expectation set by universality, we find that the Li Efimov trimer does not immediately dissociate when passing the threshold, and survives as a metastable state embedded in the atom-dimer continuum. We identify this behavior with a novel phenomena related to the emergence of a repulsive interaction in the atom-dimer channel which reshapes the three-body interactions in systems characterized by narrow Feshbach resonances. Our results shed new light on the nature of Li Efimov states and provide a new path to understand various puzzling phenomena observed here, as well as in other previous experimental studies.

The G-and V-type nerve agents are among the most toxic compounds known, where inhalation of a few mg could cause potential death. Over the years wild-type phosphotriesterase (PTE) has gained much attention due to its capability of detoxifying these deadly compounds. The underlying mechanism proceeds via a hydroxyl attack on the P or C centers of the organophosphate nerve agents followed by the departure of the leaving group. Two Zn 2+ cations present in the active site center of PTE indirectly assist the hydrolysis. Apart from the wild-type PTE, several designer enzyme variants reportedly catalyze the hydrolysis process much more efficiently. Herein, we studied the hydrolysis of eight toxic compounds with one of the enzyme variants (PTE_27) that show higher efficiency than the wild type as reported in a recent article. We docked both the high energy intermediate state and substrate for all the eight …

Efimov states are exotic and counterintuitive three-body quantum states that emerge in the vicinity of two-atom Feshbach resonances. These states exhibit remarkable characteristics as their large spatial extent and extremely weak binding energies following an infinite geometric series, and exist even when interactions are not strong enough to bind two atoms. Efimov states are universal and produce observable effects at critical values of the interaction strength across the two-body resonance when approaching their threshold for dissociation into the different types of three-body continua. In particular, as the strength of the interaction is decreased, an Efimov state merges into the atom-dimer threshold and eventually dissociates into an unbound atom-dimer pair. Here we explore this critical point using refined coherent few-body spectroscopy in Li atoms near a narrow two-body Feshbach resonance. Contrary to the expectation set by universality, we find that the Li Efimov trimer does not immediately dissociate when passing the threshold, and survives as a metastable state embedded in the atom-dimer continuum. We identify this behavior with a novel phenomena related to the emergence of a repulsive interaction in the atom-dimer channel which reshapes the three-body interactions in systems characterized by narrow Feshbach resonances. Our results shed new light on the nature of Li Efimov states and provide a new path to understand various puzzling phenomena observed here, as well as in other previous experimental studies.

A thorough understanding of biological species and of emerging nanomaterials requires, among others, their in-depth characterization with optical techniques capable of nano-resolution. Nanoscopy techniques based on tip-enhanced optical effects have gained over the past years tremendous interest given their potential to probe various optical properties with resolutions depending on the size of a sharp probe interacting with focused light, irrespective of the illumination wavelength. Although their popularity and number of applications is rising, tip-enhanced nanoscopy techniques (TEN) still largely rely on probes that are not specifically developed for such applications, but for Atomic Force Microscopy. This cages their potential in many regards, e.g. in terms of signal-to-noise ratio, attainable image quality, or extent of applications. In this article we place first steps towards next-gen TEN, demonstrating the fabrication and modelling of specialized TEN probes with known optical properties. The proposed framework is highly flexible and can be easily adjusted to be of o benefit to various types of TEN techniques, for which probes with known optical properties could potentially enable faster and more accurate imaging via different routes, such as direct signal enhancement or novel signal modulation strategies. We consider that the reported development can pave the way for a vast number of novel TEN imaging protocols and applications, given the many advantages that it offers.

Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society. However, the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction (HER) occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed. Therefore, efficient platinum group metals (PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded. In this scenario, molybdenum disulfide (MoS2) owing to efficacious structural attributes and optimum hydrogen-binding free energy (ΔGH*) is emerging as a reliable alternative to PGMs. However, the performance of MoS2-based electrocatalysts is still far away from the benchmark performance. The HER activity of MoS2 can be improved by engineering the structural parameters i.e., doping, defects inducement, modulating …