Materials Literature
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We report a self-consistent tight-binding atomic-relaxation model for titanium dioxide. We fit the parameters of the model to first-principles electronic structure calculations of the band structure and energy as a function of lattice parameters in bulk rutile. We report the method and results for the surface structur…
Local structures around Mn in ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ ($x=0.005$ and 0.074) films have been studied using Mn $K$-edge extended x-ray-absorption fine structure. In the ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ films, Mn atoms are substituted into the Ga sites…
The ac conductivity, σac of BaSnO3 has been measured in the temperature range 310–520 K and frequency range 100 Hz–1 MHz. Below 420 K the conductivity is almost independent of temperature while between 420 and 520 K it is temperature dependent. At 100 kHz the activation energy of these two regions is 0.08 and 0.35 eV,…
In contrast to their hydrocarbon analogues which exhibit only nematic mesophases, poly{5-[[[2‘,5‘-bis[(4‘‘-( n -(dimethylsiloxyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s and their low-molar-mass model compounds exhibit smectic C mesophases. Since nematic liquid crystals can be forced into laye…
Temperature and frequency dependence of the real (ε′) and imaginary (ε″) parts of the dielectric permittivity of Ba(Ti1−yYy)O3 (0.028⩽y⩽0.258) ceramic samples were studied in the temperature range 12–500 K at 102, 103, and 104, and 105 Hz. The permittivity peaks are rounded and frequency dispersive when y>0.028…
Silicified microcrystalline cellulose (SMCC) has been compared with a standard grade of microcrystalline cellulose (MCC) using several physicochemical techniques in order to elucidate any chemical or polymorphic changes in the material that could be attributed to the silicification process. Samples of SMCC, MCC and dr…
Since the rejuvenation of interest in the rare earth manganites owing to their potential use as magnetoresistive sensors, there has been adequate research to arrive at some evaluation of the potential for these materials in a variety of technologies that would use the peculiar properties of these materials. The magnet…
Scanning tunneling microscopy and first-principles atomic orbital based calculations have been used to study ${\mathrm{TiO}}_{2}(110)1\ifmmode\times\else\texttimes\fi{}2.$ A structure is proposed that resolves the controversy surrounding the surface morphology. Our model is simple, in that it consists only of atoms in…
The dilithium salts of N, N ‘, N ‘‘-tris(trimethylsilyl)diethylenetriamine ( 1 ), N -methyl- N ‘, N ‘‘-bis(trimethylsilyl)diethylenetriamine ( 2 ), and N -methyl- N ‘, N ‘‘-bis(diisopropyl)diethylenetriamine ( 3 ) reacted in THF, at −40 °C, with AlCl 3 affording monomeric aluminum chloride derivatives 4 (55% yield), 5…
Although theoretical understanding of doped mixed–valence manganites that exhibit colossal magnetoresistance (CMR) is still incomplete, the general observation of a systematic correlation at a given temperature between the magnetization and resistance both above and below the Curie temperature Tc can provide a phenome…
The morphology of a family of four 3-miktoarm star terpolymers of polystyrene (PS), polyisoprene (PI), and polymethyl methacrylate (PMMA) was studied. For three of the samples, the molecular weight of the PMMA block was systematically varied while that of the PS and PI blocks were held fixed. In the fourth sample, the…
The old coordinate driving procedure to find transition structures in chemical systems is revisited. The well-known gradient criterion, ∇E(x)=0, which defines the stationary points of the potential energy surface (PES), is reduced by one equation corresponding to one search direction. In this manner, abstract curves c…
The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces cation redistribution be…
We have measured the electrodynamic response in the metallic state of three highly anisotropic conductors, $(\mathrm{TMTSF}{)}_{2}X,$ where $X={\mathrm{PF}}_{6}$, ${\mathrm{AsF}}_{6},$ or ${\mathrm{ClO}}_{4},$ and TMTSF is the organic molecule tetramethyltetraselenofulvalene. In all three cases we find dramatic deviat…
The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, strained islands with sizes >= 10,000 atoms) grown on a GaAs (001) substrate are studied using a hybrid approach which combines density functional theory (DFT) calculations of microscopic parameters, surface energies, and surface stresses with elasti…
The first order phase transitions between a two-dimensional (2d) gas and the 2d solid of the first monolayer have been studied for the noble gases Ar, Kr and Xe on a NaCl(100) surface in quasi-equilibrium with the three-dimensional gas phase. Using linear temperature ramps, we show that the widths of the hysteresis lo…
For the example of the SiC(111)-(3x3) reconstruction we show that a holographic interpretation of discrete Low Energy Electron Diffraction (LEED) spot intensities arising from ordered, large unit cell superstructures can give direct access to the local geometry of a cluster around an elevated atom, provided there is o…
The thermally induced insulator-metal transition (IMT) has been investigated for single crystals of undoped and lightly doped ${\mathrm{LaCoO}}_{3}$ by measurements of the optical-conductivity spectra, the resistivity, and the Hall coefficient up to 800 K. The IMT around 500 K, where the spin-state transition from the…
The Entner-Doudoroff (ED) pathway was first discovered in 1952 in Pseudomonas saccharophila (21) and several years later was shown to be present in Escherichia coli (23). Although generally considered to be restricted to gram-negative bacteria, the ED pathway is present in all three phylogenetic domains, including the…
Protein-containing polyelectrolyte multilayer films of poly(styrenesulfonate) and poly(allylamine hydrochloride), fabricated by the sequential adsorption of polyelectrolyte and anti-immunoglobulin G (anti-IgG) on solid substrates, have been characterized using atomic force microscopy (AFM), scanning electron microscop…