Materials Literature
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Restricted Hartree–Fock 6-31G calculations of electrical and mechanical anharmonicity contributions to the longitudinal vibrational second hyperpolarizability have been carried out for eight homologous series of conjugated oligomers—polyacetylene, polyyne, polydiacetylene, polybutatriene, polycumulene, polysilane, pol…
Thin–film helicoidal bianisotropic mediums (TFHBMs) are rotationally non–homogeneous mediums whose microstructure consists of parallel helical columns. We characterize here the plane–wave response of non–axially excited dielectric TFHBM slabs. The constitutive relations for the dielectric TFHBMs are substituted into t…
Competitive and cooperative adsorptions of bovine serum albumin (BSA) and lysozyme (LSZ) on synthetic calcium hydroxyapatite (CaHap) were investigated at 15 °C in deionized distilled water of pH 6 by using a liquid chromatography method. The adsorption rate of LSZ was faster than that of BSA due to its larger diffusio…
Methane selective oxidation to methanol using a nonthermal pulsed plasma was investigated at room temperature and atmospheric pressure. The maximum selectivity of methanol was 47% at the methane conversion of 1.9%. It was found that the methanol selectivity is more sensitive to the input power for discharge than to ox…
Epoxidation of olefinic double bonds is of considerable importance in a variety of industries. Epoxides are raw materials for a wide variety of chemicals such as glycols, alcohols, carbonyl compounds, alkanolamines, and polymers such as polyesters, polyurethanes, and epoxy resins. Epoxidation of styrene with aqueous H…
Representative spinodal curves and polymerization lines for the equilibrium polymerization of linear polymers in a solvent have been calculated using a Flory–Huggins-type mean-field theory. The calculations are primarily restricted to systems that polymerize upon cooling, but examples are also given for systems that p…
Mixed-metal oxides play a relevant role in many areas of chemistry, physics, and materials science. We have examined the structural and electronic properties of NiMoO4 and MgMoO4 by means of synchrotron-based time-resolved x-ray diffraction (XRD), x-ray absorption near-edge spectroscopy (XANES), and first-principles d…
We propose a simple two-state model of water to explain the unusual thermodynamic and dynamic behavior of liquid water. Our model is based on a physical picture that there exist two competing orderings in water, namely, density ordering and bond ordering. Short-range bond ordering leads to the formation of a rather st…
Dynamical heterogeneity and the decoupling of diffusion and relaxation in a supercooled liquid is investigated via a time-dependent, four-point density correlation function. We show that the main contribution to the corresponding generalized susceptibility χ4(t) in a molecular dynamics simulation of a Lennard-Jones li…
A series of polyurethane compositions with soft and hard segments were prepared, and the damping and mechanical properties of these materials were studied. The damping of polyurethane was decreased and shifted to the higher temperature with the content of butanediol (BD) used as a chain extender. The mechanical proper…
Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T1x and T1y suble…
Molybdate sorption using chitosan sorbents has proved to be strictly controlled by the pH of the solution. Sorption isotherms exhibit a sigmoid trend, which has been correlated to the appearance of polynuclear hydrolyzed species, the most favorable species for sorption on chitosan. Sorption capacity exceeds 7 mmol·g−1…
High-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the adsorption of ferrocene on Ag(100) at 150 K. The HREELS data show that ferrocene adopts an orientation with the molecular axis perpendicular to the Ag(100) surface plane for low expos…
A diamond nucleation site responsible for epitaxial growth of diamond on silicon by chemical vapor deposition (CVD) is identified in high-resolution transmission electron microscopic images. Other sites in the same sample leading to polycrystalline growth, but deleterious to epitaxial CVD growth, are also described. A…
Abstract Since diffraction-line broadening is influenced by structural imperfections and the small size of crystallites (i.e. domains over which diffraction is coherent), powder diffraction is a valuable method for the determination of these properties. The theory of diffraction by imperfect solids was well establishe…
Microcalorimetric and infrared spectroscopic (FTIR) measurements for the adsorption of ethylene on Pd/SiO 2 and Pd/Sn/SiO 2 catalysts (4 wt % Pd, Pd/Sn = 3) have been performed at temperatures of 300, 263, and 233 K. In addition, microcalorimetric measurements were made for H 2 and CO adsorption and FTIR studies were…
A characteristic feature of the Portevin - Le Chatelier effect or the jerky flow is the stick-slip nature of stress-strain curves which is believed to result from the negative strain rate dependence of the flow stress. The latter is assumed to result from the competition of a few relevant time scales controlling the d…
Optical limiting behaviour of suspensions of single-walled carbon nanotubes in water, ethanol and ethylene glycol is reported. Experiments with 532 nm, 15 nsec duration laser pulses show that optical limiting occurs mainly due to nonlinear scattering. The observed host liquid dependence of optical limiting in differen…
Abstract Defect and Microstructure Analysis by Diffraction is focused on extracting information on the real structure of materials from their diffraction patterns. The primary features of a powder diffraction pattern are determined by the "idealized" periodic nature of the crystal structure. With the advent of compute…
The surface of a silica sample (Spherosil) have been modified by means of chemical treatments with sulfuric, phosphoric, and hydrochloric acids and potassium chloride. A sample also has been heated in a furnace at high temperatures. Changes in the degree of hydroxylation have been qualitatively followed by means of IR…