Materials Literature
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It is known that grain boundaries (GB's) in strontium titanate $({\mathrm{SrTiO}}_{3})$ play an important and often a controlling role in determining the material's electrical properties. To understand how their electronic structures are related to the GB structures, we have examined two structure models of the \ensur…
The ring-opening polymerization of L,L-lactide has been studied in bulk using 2-ethylhexanoic acid tin (II) salt, Sn(Oct)2, as a catalyst over a wide range of temperature and monomer to Sn(Oct)2 molar ratio. Although Sn(Oct)2 was known to initiate a fast polymerization, it is reported now that some Lewis bases, partic…
The dynamics of luminescence decay is analyzed within the general scenario of randomly distributed ions with whatever multipole interaction, taking into account energy transfer and migration processes among them. By applying Padé approximants to the Allinger and Blumen expression for the excited state population, a si…
The electronic structure and properties of the layered ceramic ${\mathrm{Ti}}_{3}{\mathrm{SiC}}_{2}$ have been examined by ab initio linear combination of atomic orbital calculations. With the calculated results we predict that the electronic conductivity of ${\mathrm{Ti}}_{3}{\mathrm{SiC}}_{2}$ is metallic and anisot…
We report systematic measurements of the temperature and field dependence of microwave losses in micron-size powders (∼3 μm) of the manganites Nd0.7Sr0.3MnO3, La0.7Ca0.3MnO3, La0.8Ba0.2MnO3, and La1.4Ca1.6Mn2O7. We fully confirm previous findings of a large increase in zero-field absorption, in La0.7Ba0.3MnO3 and La0.…
An experimental study of the electrical transport phenomena in magnetic fields H up to 15 T in pressed samples of a porous system composed of single-walled carbon nanotubes in the temperature range 1.39 K <T<300 K is reported. Below 60 K, the exp[1/T1/4] temperature dependence of the direct current elect…
In this study, indium tin oxide (ITO) films were made from an oxidized target with In2O3 and SnO2 in a weight proportion of 9:1 using the radio frequency magnetron sputtering method. Hydrogen was added to the gas mixture during the preparation of the ITO films. In order to study the effect of hydrogen partial pressure…
The periplasmic, NADP-containing glucose-fructose oxidoreductase of the gram-negative bacterium Zymomonas mobilis belongs to a class of redox cofactor-dependent enzymes which are exported with the aid of a signal peptide containing a so-called twin-arginine motif. In this paper we show that the replacement of one or b…
The archaeon Sulfolobus solfataricus grows optimally at 80 degrees C and pH 2.5 to 3.5 on carbon sources such as yeast extracts, tryptone, and various sugars. Cells rapidly accumulate glucose. This transport activity involves a membrane-bound glucose-binding protein that interacts with its substrate with very high aff…
Chemical reactions of the surface of a polypropylene (PP) film in the presence of various combinations of ultraviolet light and ozone gas (UVO) conditions were studied. Exposure of the polymer surface was carried out in a laboratory-scale UVO reactor in which the following parameters could be varied: ozone concentrati…
Current theories still fail to give a satisfactory explanation of the observed quantum phenomena in the relaxation of the magnetisation of the molecular cluster Mn 12 acetate. In the very low-temperature regime, Prokof'ev and Stamp recently proposed that slowly changing dipolar fields and rapidly fluctuating hyperfine…
In order to understand more deeply the surface enhanced Raman scattering (SERS) effect, this article develops a model, based upon the simulation of the UV–visible extinction spectra which allows the determination of the morphology of metallic particles in silver and gold colloids either unaggregated or in any aggregat…
We report a study of the interface between poly(p-phenylene vinylene) (PPV) and poly(ethylene dioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS). We find from measurements of optical absorption and conductivity that PSS dopes PPV during the sample preparation. In addition, the photoluminescence efficienc…
The crystallization behavior of amorphous Ge2Sb2Te5 thin films were investigated by using differential scanning calorimetry, x-ray diffraction, and optical reflectivity measurements. The analysis of in situ ellipsometry isotherm Ge2Sb2Te5 films based on the Johnson–Mehl–Avrami equation revealed that the crystallizatio…
Absorption spectrum of a quantum dot ensemble was found to exhibit a systematic modification with dot concentration from a set of discrete subbands inherent in isolated nanocrystals to a smooth band-edge absorption similar to that of bulk semiconductors. The results are interpreted in terms of an evolution from indivi…
In recent high resolution transmission electron microscopic studies we have found that high temperature vacuum annealing (1200–1800 K) of ultradispersed (2–5 nm) and micron size diamond produces fullerene-like graphitic species, namely, onion-like carbon and closed curved graphite structures (multilayer nanotubes and…
Evidence for the donor nature of sulfur in diamond was obtained by introducing hydrogen sulfide into the microwave assisted plasma chemical vapor deposition process. The sulfur was successfully doped into homoepitaxial diamond (100) films, which exhibit n-type conduction by Hall-effect measurements in the temperature…
The use of correlation functions to obtain the morphological parameters of crystalline-amorphous two-phase lamellar systems is critically reviewed and extended. It is shown that processing of the experimental SAXS-patterns only significantly affects the curvature of the autocorrelation triangle and that the parameters…
The use of correlation functions to obtain the morphological parameters of crystalline-amorphous two-phase lamellar systems is critically reviewed and extended. It is shown that processing of the experimental SAXS-patterns only significantly affects the curvature of the autocorrelation triangle and that the parameters…
We develop a new approach to characterizing the morphology of rough surfaces based on the analysis of the scaling properties of contour loops, i.e. loops of constant height. Given a height profile of the surface we perform independent measurements of the fractal dimension of contour loops, and the exponent that charac…