One-Step Synthesis and Operando Electrochemical Impedance Spectroscopic Characterization of Heterostructured MoP-MoN Electrocatalysts for Stable Hydrogen Evolution Reaction.

This study presents a novel synthesis of self-standing MoP and MoN heterostructured electrocatalysts with enhanced stability and catalytic performance. Facilitated by the controlled phase and interfacial microstructure, the seamless structures of these catalysts minimize internal resistivity and prevent local corrosion, contributing to increased stability. The chemical synthesis proceeds with an etching step to activate the surface, followed by phosphor-nitriding in a chemical vapor deposition chamber to produce MoP-MoN@Mo heterostructured electrocatalysts.

Role of a capping layer on the crystalline structure of Sn thin films grown at cryogenic temperatures on InSb substrates.

Metal deposition with cryogenic cooling is a common technique in the condensed matter community for producing ultra-thin epitaxial superconducting layers on semiconductors. However, a significant challenge arises when these films return to room temperature, as they tend to undergo dewetting. This issue can be mitigated by capping the films with an amorphous layer.

Insights into the Chemistry of the Cathodic Electrolyte Interphase for PTFE-Based Dry-Processed Cathodes.

Dry processing is a promising method for high-performance and low-cost lithium-ion battery manufacturing which uses polytetrafluoroethylene (PTFE) as a binder. However, the electrochemical stability of the PTFE binder in the cathodes and the generated chemistry of the cathode electrolyte interphase (CEI) layers are rarely reported. Herein, the CEI properties and PTFE electrochemical stability are studied via cycling the high-loading dry-processed electrodes in electrolytes with LiPF or LiClO salt.

Nature-Inspired Design of Nano-Architecture-Aligned NiP-NiP/NiS Arrays for Enhanced Electrocatalytic Activity of Hydrogen Evolution Reaction (HER).

The projection of developing sustainable and cost-efficient electrocatalysts for hydrogen production is booming. However, the full potential of electrocatalysts fabricated from earth-abundant metals has yet to be exploited to replace Pt-group metals due to inadequate efficiency and insufficient design strategies to meet the ever-increasing demands for renewable energies. To improve the electrocatalytic performance, the primary challenge is to optimize the structure and electronic properties by enhancing the intrinsic catalytic activity and expanding the active catalytic surface area.

Chiral electrocatalysts eclipse water splitting metrics through spin control.

Continual progress in technologies that rely on water splitting are often hampered by the slow kinetics associated with the oxygen evolution reaction (OER). Here, we show that the efficiency of top-performing catalysts can be improved, beyond typical thermodynamic considerations, through control over reaction intermediate spin alignment during electrolysis. Spin alignment is achieved using the chiral induced spin selectivity (CISS) effect and the improvement in OER manifests as an increase in Faradaic efficiency, decrease in reaction overpotential, and change in the rate determining step for chiral nanocatalysts over compositionally analogous achiral nanocatalysts.

Atomic-scale observation of dynamic grain boundary structural transformation during shear-mediated migration.

Grain boundary (GB) structural change is commonly observed during and after stress-driven GB migration in nanocrystalline materials, but its exact atomic scale transformation has not been explored experimentally. Here, using in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations, we observed the dynamic GB structural transformation stemming from reversible facet transformation and GB dissociation during the shear-mediated migration of faceted GBs in gold nanocrystals. A reversible transformation was found to occur between (002)/(111) and Σ11(113) GB facets, accomplished by the coalescence and detachment of [Formula: see text]-type GB steps or disconnections that mediated the GB migration.

Generation of hyaline-like cartilage tissue from human mesenchymal stromal cells within the self-generated extracellular matrix.

Chondrocytic hypertrophy, a phenotype not observed in healthy hyaline cartilage, is often concomitant with the chondrogenesis of human mesenchymal stromal cells (hMSCs). This undesired feature represents one of the major obstacles in applying hMSCs for hyaline cartilage repair. Previously, we developed a method to induce hMSC chondrogenesis within self-generated extracellular matrix (mECM), which formed a cartilage tissue with a lower hypertrophy level than conventional hMSC pellets.

Atomic-scale friction between single-asperity contacts unveiled through in situ transmission electron microscopy.

Friction and wear are detrimental to functionality and reduce the service life of products with mechanical elements. Here, we unveil the atomic-scale friction of a single tungsten asperity in real time through a high-resolution transmission electron microscopy investigation of a nanocontact in countermotion, induced through a piezo actuator. Molecular dynamics simulations provide insights into the sliding pathway of interface atoms and the dynamic strain/stress evolution at the interface.

Room temperature doping of Ln in perovskite nanoparticles: a halide exchange mediated cation exchange approach.

This study presents a halide exchange mediated cation exchange strategy for a room temperature doping of trivalent lanthanide cations (Ln) in cesium lead halide (CsPbX) nanoparticles (NPs). Post-synthetic addition of LnCl [Ln = Nd, Sm, Eu, Tb, Dy, and Yb] to a solution of CsPbBr NPs generates the corresponding lanthanide doped NPs which display host sensitized Ln emission. Structural and spectroscopic characterizations indicate a successful halide exchange and substitutional displacement of Pb by Ln.

Engineering pre-vascularized bone-like tissue from human mesenchymal stem cells through simulating endochondral ossification.

Currently, most in vitro engineered bone tissues do not contain viable blood vessel systems, so the vascularization depends on post-implantation angiogenesis from the host, which is often insufficient for repairing large bone defects. In this study, we aimed to create pre-vascularized bone-like tissue from human bone marrow-derived mesenchymal stem cells (HBMSCs) within the self-generated extracellular matrix by simulating the developmental endochondral ossification. Afterward, a three-dimensional (3D) culture of human umbilical vein endothelial cells (HUVECs)/HBMSCs was introduced to cover bone-like constructs surface for vascularization.

Surface nanostructuring of alkali-aluminosilicate Gorilla display glass substrates using a maskless process.

This paper reports on the formation of moth-eye nanopillar structures on surfaces of alkali-aluminosilicate Gorilla glass substrates using a self-masking plasma etching method. Surface and cross-section chemical compositions studies were carried out to study the formation of the nanostructures. CFinduced polymers were shown to be the self-masking material during plasma etching.

Peptoid-Directed Formation of Five-Fold Twinned Au Nanostars through Particle Attachment and Facet Stabilization.

While bio-inspired synthesis offers great potential for controlling nucleation and growth of inorganic particles, precisely tuning biomolecule-particle interactions is a long-standing challenge. Herein, we used variations in peptoid sequence to manipulate peptoid-Au interactions, leading to the synthesis of concave five-fold twinned, five-pointed Au nanostars via a process of repeated particle attachment and facet stabilization. Ex situ and liquid-phase TEM observations show that a balance between particle attachment biased to occur near the star points, preferential growth along the [100] direction, and stabilization of (111) facets is critical to forming star-shaped particles.

Using post-synthetic ligand modification to imprint chirality onto the electronic states of cesium lead bromide (CsPbBr) perovskite nanoparticles.

This study presents a post-synthetic ligand modification strategy for the generation of chiroptically active, blue emitting CsPbBr nanoparticles (NPs) - an expansion to the library of 3D chiral perovskite nanomaterials. Addition of [- and -] 1-phenylethylamine, 1-(1-naphthyl)ethylamine, or 2-aminooctane to the synthesized CsPbBr NPs is shown to induce Cotton effects in the NP first exciton transition, suggestive of a successful electronic coupling between the chiral ligands and the NPs. The availability of these chiral CsPbBr NPs thrusts them into the forefront of perovskite nanomaterials for examining the implications of the chiral induced spin selectivity (CISS) effect and other applications in spintronics.

Thermal diffusivity measurement of microscale slabs by rear-surface detection thermoreflectance technique.

A new approach to measure the cross-plane thermal diffusivity of a microscale slab sample, which can be fabricated by the focused ion beam and attached to a substrate, is proposed. An intensity-modulated pump laser is applied to heat the front surface of the sample uniformly, and the thermoreflectance signal is observed at the rear surface to evaluate thermal wave transport in the material. The thermal diffusivity can be obtained by fitting the phase lags of the experimental data with a theoretical model.

Characterization of the structure, vascularity, and stem/progenitor cell populations in porcine Achilles tendon (PAT).

This study aimed to characterize porcine Achilles tendon (PAT) in terms of its structural components, vascularity, and resident tendon cells. We found that PAT is composed of a paratenon sheath, a core of fascicles, and an endotenon/interfascicular matrix (IFM) that encases the fascicle bundles. We analyzed each of these three tendon components structurally using tissue sections and by isolating cells from each component and analyzing in vitro.

Germanium Quantum-Well Josephson Field-Effect Transistors and Interferometers.

Hybrid superconductor-semiconductor structures attract increasing attention owing to a variety of potential applications in quantum computing devices. They can serve the realization of topological superconducting systems as well as gate-tunable superconducting quantum bits. Here, we combine a SiGe/Ge/SiGe quantum-well heterostructure hosting high-mobility two-dimensional holes and aluminum superconducting leads to realize prototypical hybrid devices, such as Josephson field-effect transistors (JoFETs) and superconducting quantum interference devices (SQUIDs).

Anticorrosive Self-Assembled Hybrid Alkylsilane Coatings for Resorbable Magnesium Metal Devices.

Magnesium (Mg) and its alloys are promising candidates for use as resorbable materials for biomedical devices that can degrade in situ following healing of the defect, eliminating the need for a second surgery to remove the device. Hydrogen gas is the main product of magnesium corrosion, and one of the limitations for use of Mg devices in clinic is the formation of gas pockets around them. One potential solution to this problem is reducing the rate of corrosion to the levels at which H can diffuse through the body fluids.

Hierarchical graphene/metal grid structures for stable, flexible transparent conductors.

We report an experimental study on the fabrication and characterization of hierarchical graphene/metal grid structures for transparent conductors. The hierarchical structure allows for uniform and local current conductivity due to the graphene and exhibits low sheet resistance because the microscale silver grid serves as a conductive backbone. Our samples demonstrate 94% diffusive transmission with a sheet resistance of 0.

"Zero-dimensional" single-walled carbon nanotubes.

The shorter, the more dispersible: An iterative, emulsion-based shortening technique has been used to reduce the length of single-walled carbon nanotubes (SWNTs) to the same order of magnitude as their diameter (ca. 1 nm), thus achieving an effectively "zero-dimensional" structure with improved dispersibility and, after hydroxylation, long-term water solubility. Finally, zero-dimensional SWNTs were positively identified using mass spectrometry for the first time.

Pure Graphene Oxide Doped Conducting Polymer Nanocomposite for Bio-interfacing.

Advanced materials that are highly biocompatible and easily modifiable with biomolecules are of great importance for bio-interfacing and the development of biodevices. Here, a biocompatible conducting polymer based nanocomposite was electrochemically synthesized through the electropolymerization of poly(3, 4-ethylene dioxythiophene) (PEDOT) in the presence of graphene oxide (GO) as the only dopant. GO contains many negatively charged carboxyl functional groups and is highly dispersible in aqueous solutions, enabling its facile incorporation and even distribution throughout the conducting polymer.

Carbon nanotube nanoreservior for controlled release of anti-inflammatory dexamethasone.

On demand release of anti-inflammatory drug or neurotropic factors have great promise for maintaining a stable chronic neural interface. Here we report the development of an electrically controlled drug release system based on conducting polymer and carbon nanotubes. Drug delivery research using carbon nanotubes (CNTs) has taken advantage of the ability of CNTs to load large amounts of drug molecules on their outer surface.

Negligible absorption of radiofrequency radiation by colloidal gold nanoparticles.

We report quantitative measurement of heat generation in Au-nanoparticle colloidal solutions induced by radiofrequency (RF) electromagnetic waves (13.56 MHz; 25 W). The possible role of Au nanoparticles in RF heating was systematically investigated by separating the metal nanoparticles away from the colloidal solutions by centrifugation.

Charge-selective Raman scattering and fluorescence quenching by "nanometal on semiconductor" substrates.

Ag nanoparticles synthesized on n and p-type Si were shown to exhibit charge-selective surface-enhanced Raman scattering and fluorescence quenching. As revealed by electric force microscopy, the polarity and magnitude of the nanoparticle charge is controllable with the metal-semiconductor Fermi level difference and nanoparticle size. It is inferred that the Fermi level alignment is dominantly contributed by the charge-induced nanoparticle voltage.

Attraction between weakly charged silica spheres at a water-air interface induced by surface-charge heterogeneity.

We report an optical and atomic force microscopic (AFM) study of interactions between weakly charged silica spheres at a water-air interface. Attractive interactions are observed at intermediate interparticle distances and the amplitude of the attraction increases with the amount of salt (NaCl) added into the water phase. AFM images obtained in the salty water show the formation of patchy charge domains of size approximately 100 nm on the silica surface.