Five coordinated Mn in BaMnSiTe: synthesis, crystal structure, physical properties, and electronic structure.

We report the synthesis of single-crystals of a new transition metal-containing quaternary chalcogenide, BaMnSiTe, synthesized by the solid-state method at 1273 K. A single-crystal X-ray diffraction study shows that it crystallizes in the orthorhombic crystal system (space group: ) with cell constants of = 13.4690(6) Å, = 8.

Heterostructures of tin and tungsten selenides for robust overall water splitting.

Layered transition metal selenides have garnered increased attention in recent times as non-noble metal bifunctional electrocatalysts for electrochemical water splitting. Tungsten diselenide @ tin diselenide heterostructures in the present study significantly increase the electrochemical performance of oxygen evolution reaction with a low overpotential of 250 mV at 10 mA cm and high stability for 16 h (8.9 % loss), hydrogen evolution reaction with a low overpotential of 180 mV at 10 mA cm with a 21.

Nanostructured Silicon-Carbon 3D Electrode Architectures for High-Performance Lithium-Ion Batteries.

Silicon is an attractive anode material for lithium-ion batteries. However, silicon anodes have the issue of volume change, which causes pulverization and subsequently rapid capacity fade. Herein, we report organic binder and conducting diluent-free silicon-carbon 3D electrodes as anodes for lithium-ion batteries, where we replace the conventional copper (Cu) foil current collector with highly conductive carbon fibers (CFs) of 5-10 μm in diameter.

Single Electron Precision in the Measurement of Charge Distributions on Electrically Biased Graphene Nanotips Using Electron Holography.

We use off-axis electron holography to measure the electrostatic charge density distributions on graphene-based nanogap devices that have thicknesses of between 1 and 10 monolayers and separations of between 8 and 58 nm with a precision of better than a single unit charge. Our experimental measurements, which are compared with finite element simulations, show that wider graphene tips, which have thicknesses of a single monolayer at their ends, exhibit charge accumulation along their edges. The results are relevant for both fundamental research on graphene electrostatics and applications of graphene nanogaps to single nucleotide detection in DNA sequencing, single molecule electronics, plasmonic antennae, and cold field emission sources.

Distortion of DNA Origami on Graphene Imaged with Advanced TEM Techniques.

While graphene may appear to be the ultimate support membrane for transmission electron microscopy (TEM) imaging of DNA nanostructures, very little is known if it poses an advantage over conventional carbon supports in terms of resolution and contrast. Microscopic investigations are carried out on DNA origami nanoplates that are supported onto freestanding graphene, using advanced TEM techniques, including a new dark-field technique that is recently developed in our lab. TEM images of stained and unstained DNA origami are presented with high contrast on both graphene and amorphous carbon membranes.

In-situ STEM imaging of growth and phase change of individual CuAl precipitates in Al alloy.

Age-hardening in Al alloys has been used for over a century to improve its mechanical properties. However, the lack of direct observation limits our understanding of the dynamic nature of the evolution of nanoprecipitates during age-hardening. Using in-situ (scanning) transmission electron microscopy (S/TEM) while heating an Al-Cu alloy, we were able to follow the growth of individual nanoprecipitates at atomic scale.

Nanometre-scale evidence for interfacial dissolution-reprecipitation control of silicate glass corrosion.

Silicate glasses are durable solids, and yet they are chemically unstable in contact with aqueous fluids-this has important implications for numerous industrial applications related to the corrosion resistance of glasses, or the biogeochemical weathering of volcanic glasses in seawater. The aqueous dissolution of synthetic and natural glasses results in the formation of a hydrated, cation-depleted near-surface alteration zone and, depending on alteration conditions, secondary crystalline phases on the surface. The long-standing accepted model of glass corrosion is based on diffusion-coupled hydration and selective cation release, producing a surface-altered zone.

Plasma nitriding induced growth of Pt-nanowire arrays as high performance electrocatalysts for fuel cells.

In this work, we demonstrate an innovative approach, combing a novel active screen plasma (ASP) technique with green chemical synthesis, for a direct fabrication of uniform Pt nanowire arrays on large-area supports. The ASP treatment enables in-situ N-doping and surface modification to the support surface, significantly promoting the uniform growth of tiny Pt nuclei which directs the growth of ultrathin single-crystal Pt nanowire (2.5-3 nm in diameter) arrays, forming a three-dimensional (3D) nano-architecture.

Real-time atomic scale imaging of nanostructural evolution in aluminum alloys.

We present a new approach to study the three-dimensional compositional and structural evolution of metal alloys during heat treatments such as commonly used for improving overall material properties. It relies on in situ heating in a high-resolution scanning transmission electron microscope (STEM). The approach is demonstrated using a commercial Al alloy AA2024 at 100-240 °C, showing in unparalleled detail where and how precipitates nucleate, grow, or dissolve.

Localised corrosion in aluminium alloy 2024-T3 using in situ TEM.

An approach to carry out chemical reactions using aggressive gases in situ in a transmission electron microscope (TEM), at ambient pressures of 1.5 bar using a windowed environmental cell, called a nanoreactor, is presented here. The nanoreactor coupled with a specially developed holder with platinum tubing permits the usage of aggressive chemicals like hydrochloric acid (HCl).

Tailoring the hydrophobicity of graphene for its use as nanopores for DNA translocation.

Graphene nanopores are potential successors to biological and silicon-based nanopores. For sensing applications, it is however crucial to understand and block the strong nonspecific hydrophobic interactions between DNA and graphene. Here we demonstrate a novel scheme to prevent DNA-graphene interactions, based on a tailored self-assembled monolayer.

Controllable atomic scale patterning of freestanding monolayer graphene at elevated temperature.

We show that by operating a scanning transmission electron microscope (STEM) with a 0.1 nm 300 kV electron beam, one can sculpt free-standing monolayer graphene with close-to-atomic precision at 600 °C. The same electron beam that is used for destructive sculpting can be used to image the sculpted monolayer graphene nondestructively.

Polyaniline hollow fibres for organic solvent nanofiltration.

Intrinsically-skinned asymmetric PANi hollow fibres, fabricated using a process of directly adding large organic acids to highly concentrated PANi solutions, show stability in a wide variety of organic solvents and have shown promising nanofiltration properties, giving high rejections of nanosolutes in acetone.

Molecular modeling simulations to predict compatibility of poly(vinyl alcohol) and chitosan blends: a comparison with experiments.

Molecular modeling simulations are the most important tools to predict blend compatibility of polymers that are otherwise difficult to predict by experimental means. Conflicting reports have been reported on the blend compatibility of poly(vinyl alcohol), PVA, and chitosan, CS polymers. Since both the polymers are widely used in pharmaceutics as drug-loaded particulates and as separation membranes, we felt it necessary to investigate their compatibility over the practical range of compositions.

Development of 5-fluorouracil loaded poly(acrylamide-co-methylmethacrylate) novel core-shell microspheres: in vitro release studies.

Novel poly(acrylamide-methylmethacrylate) copolymeric core-shell microspheres crosslinked with N,N'-methylene bisacrylamide have been prepared by free radical emulsion polymerization using varying amounts of acrylamide (AAm), methylmethacrylate (MMA) and N,N'-methylene bisacrylamide (NNMBA). 5-Fluorouracil was loaded into these microspheres during in situ polymerization (method-I) as well as by the absorption and adsorption technique (method-II). The core-shell microspheres have been characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (X-RD) to understand about the drug dispersion in microspheres.

Molecular modeling on the binary blend compatibility of poly(vinyl alcohol) and poly(methyl methacrylate): an atomistic simulation and thermodynamic approach.

Computer simulations play an important role in designing new polymers as well as in predicting properties of existing polymers. In this paper, the blend compatibility of poly(vinyl alcohol) (PVA) with poly(methyl methacrylate) (PMMA) was studied over the wide range of compositions allowed by the atomistic and mesoscopic simulation methods. The Flory-Huggins interaction parameter, chi, of the blends computed using the atomistic simulation confirmed the blend compatibility for compositions containing >60 wt % of PVA.

Encapsulation efficiency and controlled release characteristics of crosslinked polyacrylamide particles.

Polyacrylamide (pAAm) particles crosslinked with N,N-methylenebis-acrylamide/ethylene glycol dimethacrylate (NNMBA/EGDMA) have been prepared in water-methanol medium by the dispersion polymerization using poly(vinyl pyrrolidone), PVP as a steric stabilizer. 5-fluorouracil an anticancer drug, has been loaded in situ into the crosslinked pAAm particles. Plain as well as drug loaded microparticles have been characterized by differential scanning calorimetry (DSC) and X-ray diffraction studies (XRD) and scanning electron microscopy (SEM).

Targeted nanoparticles for drug delivery through the blood-brain barrier for Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia among the elderly, affecting 5% of Americans over age 65, and 20% over age 80. An excess of senile plaques (beta-amyloid protein) and neurofibrillary tangles (tau protein), ventricular enlargement, and cortical atrophy characterizes it. Unfortunately, targeted drug delivery to the central nervous system (CNS), for the therapeutic advancement of neurodegenerative disorders such as Alzheimer's, is complicated by restrictive mechanisms imposed at the blood-brain barrier (BBB).