Mechanical Amorphization of Chitosan with Different Molecular Weights.

Mechanical amorphization of three chitosan samples with high, medium, and low molecular weight was studied. It is shown that there are no significant differences between the course of amorphization process in a planetary ball mill of chitosan with different molecular weights, and the maximum degree of amorphization was achieved in 600 s of high intensity mechanical action. Specific energy consumption was 28 kJ/g, being comparable to power consumption for amorphization of cellulose determined previously (29 kJ/g) and 5-7-fold higher than that for amorphization of starch (4-6 kJ/g).

Structural and Transport Properties of E-Beam Sintered Lanthanide Tungstates and Tungstates-Molybdates.

Lanthanide tungstates and molybdates are promising materials for hydrogen separation membranes due to their high protonic conductivity. A promising approach to fabricating ceramics based on these materials is radiation thermal sintering. The current work aims at studying the effect of radiation thermal sintering on the structural morphological and transport properties of (Nd,Ln)(W,Mo)O as promising materials for hydrogen separation membranes.

Constrained Density Functional Theory: A Potential-Based Self-Consistency Approach.

Chemical reactions, charge transfer reactions, and magnetic materials are notoriously difficult to describe within Kohn-Sham density functional theory, which is strictly a ground-state technique. However, over the last few decades, an approximate method known as constrained density functional theory (cDFT) has been developed to model low-lying excitations linked to charge transfer or spin fluctuations. Nevertheless, despite becoming very popular due to its versatility, low computational cost, and availability in numerous software applications, none of the previous cDFT implementations is strictly similar to the corresponding ground-state self-consistent density functional theory: the target value of constraints (e.

A Feasibility Study of High-Entropy Alloy Coating Deposition by Detonation Spraying Combined with Laser Melting.

In this work, a new two-stage approach to the deposition of high-entropy alloy coatings is proposed. At the first stage, a composite precursor coating is formed by detonation spraying of the metal powder mixtures. At the second stage, the precursor coating is re-melted by a laser, and the formation of multi-component solid solution phases can be expected upon solidification.

Understanding of the Mechanism and Kinetics of the Fast Solid-State Reaction between NaF and VPO to Form NaV(PO)F.

The solid-state reaction between NaF and VPO is widely used to produce NaV(PO)F, a promising cathode material for sodium-ion batteries. In the present work, the mechanism and kinetics of the reaction between NaF and VPO were investigated, and the effect of preliminary high-energy ball milling (HEBM) was studied using time-resolved synchrotron powder X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, etc. The reaction was attributed to a "dimensional reduction" formalism; it proceeds quickly with the unilateral diffusion of Na and F ions into VPO particles as a limiting stage.

Experimental Testing of the Action of Vitamin D and Silicon Chelates in Bone Fracture Healing and Bone Turnover in Mice and Rats.

This study presents findings on the biological action of an integrated supplement containing the following components involved in osteogenesis and mineralization: vitamin D and silicon in the bioavailable and soluble form. A hypothesis that these components potentiate one another's action and make calcium absorption by the body more efficient was tested. Biological tests of the effect of vitamin D and silicon chelates on bone fracture healing and bone turnover were conducted using ICR mice and albino Wistar rats.

Morphological and Structural Transformations of Fe-Pd Powder Alloys Formed by Galvanic Replacement, Annealing and Acid Treatment.

In this article, we report the preparation and structural features of Fe-Pd powder alloys formed by galvanic replacement, annealing and selective dissolution of iron via acid treatment. The alloys were studied by the X-ray diffraction phase analysis, Mössbauer spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The Fe@Pd core-shell particles were obtained by a galvanic replacement reaction occurring upon treatment of a body-centered cubic (bcc) iron powder by a solution containing PdCl ions.

Pseudopotentials of Elements for Solid-State NMR.

Computational methods are increasingly used to support interpreting, assigning and predicting the solid-state nuclear resonance magnetic spectra of materials. Currently, density functional theory is seen to achieve a good balance between efficiency and accuracy in solid-state chemistry. To be specific, density functional theory allows the assignment of signals in nuclear resonance magnetic spectra to specific sites and can help identify overlapped or missing signals from experimental nuclear resonance magnetic spectra.

Core-Shell Particle Reinforcements-A New Trend in the Design and Development of Metal Matrix Composites.

Metal matrix composites (MMCs) are a constantly developing class of materials. Simultaneously achieving a high strength and a high ductility is a challenging task in the design of MMCs. This article aims to highlight a recent trend: the development of MMCs reinforced with particles of core-shell structure.

Elimination of Composition Segregation in 33Al-45Cu-22Fe (at.%) Powder by Two-Stage High-Energy Mechanical Alloying.

In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al-45Cu-22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts.

Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides.

Lithium-excess oxides LiTiMnO and LiNbMnO with a disordered rock-salt structure and Mn/Mn as a redox couple were compared to analyze the effect of different d metal ions on the local structure and Li ion migration. These cathode materials were obtained by mechanochemically assisted solid-state synthesis. Using XRD, Li NMR and EPR spectroscopy and transmission electron microscopy it was shown that the Mn ions are prone to form clusters, while d metal ions are evenly distributed in the crystal lattice.

Relating Excited States to the Dynamics of Macroscopic Strain in Photoresponsive Crystals.

Exposure of a photoreactive single crystal to light with a wavelength offset from its absorption maximum can have two distinct effects. The first is the "direct" effect, wherein the excited state generated in individual chemical species is influenced. The second is the "indirect" effect, which describes the penetration of light into the crystal and hence the spatial propagation and completeness of transformation.

Immobilized Bisphosphonates as Potential Inhibitors of Bioprosthetic Calcification: Effects on Various Xenogeneic Cardiovascular Tissues.

Calcification is the major factor limiting the clinical use of bioprostheses. It may be prevented by the immobilization of bisphosphonic compounds (BPs) on the biomaterial. In this study, we assessed the accumulation and structure of calcium phosphate deposits in collagen-rich bovine pericardium (Pe) and elastin-rich porcine aortic wall (Ao) and bovine jugular vein wall (Ve) cross-linked with glutaraldehyde (GA) or diepoxy compound (DE).

Thermochemical electronegativities of the elements.

Electronegativity is a key property of the elements. Being useful in rationalizing stability, structure and properties of molecules and solids, it has shaped much of the thinking in the fields of structural chemistry and solid state chemistry and physics. There are many definitions of electronegativity, which can be roughly classified as either spectroscopic (these are defined for isolated atoms) or thermochemical (characterizing bond energies and heats of formation of compounds).

Computational Modeling of 2D Materials under High Pressure and Their Chemical Bonding: Silicene as Possible Field-Effect Transistor.

To study the possibility for silicene to be employed as a field-effect transistor (FET) pressure sensor, we explore the chemistry of monolayer and multilayered silicene focusing on the change in hybridization under pressure. computations show that the effect of pressure depends greatly on the thickness of the silicene film, but also reveals the influence of real experimental conditions, where the pressure is not hydrostatic. For this purpose, we introduce anisotropic strain states.

Ionic Transport in CsNO-Based Nanocomposites with Inclusions of Surface Functionalized Nanodiamonds.

Composite solid electrolytes (1-x) CsNO-xND, where ND are nanodiamonds, including those after liquid-phase and gas-phase oxidation and reduction functionalization, were prepared, and their properties investigated by XRD, analysis of BET nitrogen adsorption isotherms, IR spectroscopy and impedance spectroscopy. The electrical conductivity of composites (1-x) CsNO-xND obeys the Arrhenius dependence and has a maximum at x = 0.95 regardless of the ND pretreatment.

Mechanochemical and Size Reduction Machines for Biorefining.

In recent years, we have witnessed an increasing interest in the application of mechanochemical methods for processing materials in biomass refining techniques. Grinding and mechanical pretreatment are very popular methods utilized to enhance the reactivity of polymers and plant raw materials; however, the choice of devices and their modes of action is often performed through trial and error. An inadequate choice of equipment often results in inefficient grinding, low reactivity of the product, excess energy expenditure, and significant wear of the equipment.

Preparation of porous Co-Pt alloys for catalytic synthesis of carbon nanofibers.

A simple and convenient procedure for the production of highly dispersed porous Co-Pt alloys to be used as catalysts for the synthesis of nanostructured carbon fibers (CNF) has been developed. The technique is based on the thermal decomposition of specially synthesized multicomponent precursors in a reducing atmosphere. A series of porous single-phase alloys Co-Pt (10-75 at% Pt) have been synthesized.

Synthesis of bismuth (III) oxofumarate and its solubility in organic solvents.

This paper present the synthesis of bismuth (III) oxofumarate (BiO)CHO by solution-solid reaction due to the interaction of basic bismuth nitrates [BiO(OH)](NO)·3HO and [BiO(OH)](NO)·HO with aqueous solutions of fumaric acid CHO. Solubility of (BiO)CHO in various organic solvents has been investigated. The morphology and phase composition of the samples was established by X-ray diffraction, scanning electron microscopy, thermogravimetric and chemical analyzes.

Crystal structure and migration paths of alkaline ions in NaVPOF.

A sample with a nominal composition 'NaVPO4F' is prepared by mechanochemically assisted solid-state synthesis using quenching. A detailed study of its crystal and local structure is conducted by means of XRD and FTIR and solid-state 31P NMR spectroscopies in comparison with Na3V2(PO4)2F3. It is shown that the as-prepared 'NaVPO4F' has a multiphase composition, including NaVPO4F as the main phase and Na3V2(PO4)2F3 and Na2.

Unbound water in mechanochemical reactions of brown coal.

Mechanochemical activation of coal is commonly employed in industry. However, even the simplest solid-phase reactions, such as neutralization of humic acids in brown coal, remain insufficiently studied. The hypothesis regarding the occurrence of mechanochemical neutralization under local hydrothermal conditions for humic acids in brown coal has been tested in this study.

Combustion of Titanium-Carbon Black High-Energy Ball-Milled Mixtures in Nitrogen: Formation of Titanium Carbonitrides at Atmospheric Pressure.

In this work, titanium carbonitrides were synthesized by self-propagating high-temperature synthesis (SHS) in nitrogen. For the first time, the synthesis of titanium carbonitrides by combustion was realized in nitrogen at atmospheric pressure. The synthesis was carried out by subjecting high-energy ball-milled titanium-carbon black powder mixtures to combustion in a nitrogen atmosphere.