Materials Literature
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ENIGMA ( Electron and Nuclear Image Generator by Max-ent Analysis ) is a program package to evaluate three-dimensional electron and nuclear density from X-ray and neutron diffraction data by using the maximum-entropy method (MEM). Compared with the previous program package MEED , ENIGMA saves computing time and frees…
Neutron total scattering provides simultaneous information about long-range order through the Bragg peaks and short- range order through the diffuse scattering. We review recent progress in applying total scattering methods for the study of short- range structural order in silicates and other materials, focussing on c…
The local-spin-density approximation and the generalized-gradient approximation (GGA) are used to perform density-functional total-energy calculations at zero temperature for ${\mathrm{Fe}}_{3}\mathrm{Al}$ in the ordered ${D0}_{3}$ and ${L1}_{2}$ structures. Our calculations show that commonly used GGA functionals fai…
Cubic Pt nanoparticles were prepared by NaBH 4 reduction of K 2 PtCl 6 in an aqueous medium. Under the effect of phase-transfer inducer HCl, Pt nanoparticles were transferred to a toluene solution containing dodecanethiol, forming a toluene organosol of cubic Pt nanoparticles protected by dodecanethiol. A monolayer of…
Local and electronic structures of Ni and Mn atoms in the ${\mathrm{LaNi}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}{\mathrm{O}}_{3+\ensuremath{\delta}}$ series were studied by means of x-ray-absorption spectroscopy. The Ni and Mn K edges and Mn ${L}_{3}{/L}_{2}$ edges were analyzed. The local structure, determined by exten…
Polyelectrolyte complex formation of chitosans of varying average molecular weight and degree of acetylation with chitosan sulfate or poly(styrene sulfonate) was studied by static light scattering in dilute solution at various ionic strengths. Unlike the molecular weight, the degree of acetylation was found to have a…
We perform ab initio calculations of optical properties for a typical semiconductor conjugated polymer, poly-para-phenylenevinylene, in both isolated chain and crystalline packing. In order to obtain results for excitonic energies and real-space wavefunctions we explicitly include electron-hole interaction within the…
Superconducting Ag or Cu sheathed MgB2 wires have been fabricated by conventional powder-in-tube techniques. The in-situ reaction of Mg and B powders with atomic proportions of 1:2 and 1.33:2 inside Ag or Cu tubes at low temperatures have been searched. An active alloying of Mg with Ag or Cu sheaths at temperatures be…
Within dynamical mean-field theory, we study the metal-insulator transition of a twofold orbitally degenerate Hubbard model as a function of a splitting Δof the degeneracy. The phase diagram in the U-Δplane exhibits two-band and one-band metals, as well as the Mott insulator. The correlated two-band metal is easily dr…
We investigate the possibility of preparing left-handed materials in metallic magnetic granular composites. Based on the effective medium approximation, we show that by incorporating metallic magnetic nanoparticles into an appropriate insulating matrix and controlling the directions of magnetization of metallic magnet…
Although non-merohedrally twinned crystal structures can normally be solved without difficulty, problems usually arise during refinement. Careful analysis of poorly fitting data reveals that they belong predominantly to certain distinct zones in which | F o | 2 is systematically larger than | F c | 2 . In the computer…
The molecular dynamics method was used to simulate energy transport in \ensuremath{\alpha}- and $\ensuremath{\beta}\ensuremath{-}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ single crystals. The simulation data, in conjunction with the Green-Kubo formulation, was used to calculate the thermal conductivity of the single crystals…
In a recent paper an implicit equation for contacting viscoelastic spheres was derived (Brilliantov et al. PRE 53, 5382 (1996)). Integrating this equation it can be shown that the coefficient of normal restitution depends on the impact velocity as 1-ε\sim g^{1/5}.
The constitutive relation of the quasi-static deformation on two dimensional packed samples of polygons is calculated using molecular dynamic simulations. The stress values at which the system remains stable are bounded by a failure surface, that shows a power law dependence on the pressure. Below the failure surface,…
The problem for interface solutions in the quantum theory of heterostructures comprising narrow-gap semiconductors is reformulated in the language of commutative diagrams. By this way the theory of interface states in such heterostructures is naturally factorized in the two subproblems: (i) Criterion for the existence…
An approach that enables up to a two order of magnitude reduction in the amount of protein required and a tenfold reduction in the amount of time required for vapor-diffusion protein crystallization is reported. A prototype high-throughput automated system was used for the production of diffraction-quality crystals fo…
Although luminescent complexes of lanthanide ions and organic ligands have been studied intensively, relatively little attention has been paid to the natural (or ‘radiative’) lifetime of the lanthanide centered luminescent state in these systems. Here, the applicability of the well-known Judd–Ofelt theory to the emiss…
Abstract Lanthanum chromium oxide (LaCrO 3 ) has excellent high‐temperature properties. LaCrO 3 doped with alkaline earth metals also has high electric conductivity. The purpose of this study is to fabricate thin film heaters using LaCrO 3 doped with Ca by RF magnetron sputtering method. The crystal structure of thin…
The structure of the title compound, [Cu(C(6)H(7)N)(2)(Ag(CN)(2)(2)](n), is made up of neutral zigzag chains of [-NC-Ag-CN-Cu(4-Mepy)(2)(Ag(CN)(2))-NC-Ag-CN-] (4-Mepy is 4-methylpyridine). Neighbouring chains are linked by weak argentophilic interactions, with Ag.Ag distances of 3.2322 (12) A. The Cu atom, which lies…
The longitudinal (R1) and transverse (R2) relaxivities of the clinically used contrast agents Gd(DTPA)2-, Gd(DOTA)- and Gd(DTPA-BMA) have been determined in mixed aqueous metabolite solutions for choline, creatine and N-acetylaspartate. Measurements were performed at 1.5 T using a STEAM sequence on 25 mM metabolite so…