Materials Literature
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We have studied the optical properties of metallic nanoparticles with arbitrary shape. We performed theoretical calculations of the absorption, extinction, and scattering efficiencies, which can be directly compared with experiments, using the discrete dipole approximation (DDA). In this work, the main features in the…
The extinction coefficient per mole of nanocrystals at the first exitonic absorption peak, ε, for high-quality CdTe, CdSe, and CdS nanocrystals was found to be strongly dependent on the size of the nanocrystals, between a square and a cubic dependence. The measurements were carried out using either nanocrystals purifi…
We present a comprehensive study of minority carrier lifetime and recombination mechanisms in n-InP single crystals. The study is based on steady state and time-resolved photoluminescence measurements in a wide temperature range (15–300 K). Various recombination and trapping mechanisms are analyzed and compared in ord…
An efficient green chemistry approach to the synthesis of N-substituted piperidones and piperidines was developed and applied to the synthesis of 1-(2-pyridinylmethyl)-piperidin-4-one, 1, a key starting material for the synthesis of LY317615, an antiangiogenic agent currently under development at Eli Lilly and Company…
The evolution of the Lewis acidity of a MgAl hydrotalcite sample (Mg/Al ratio of 4) during thermal treatment in vacuo at different temperatures was followed by means of FTIR spectroscopy of CO adsorbed at 85 K. The materials were also characterized by XRD, TG-DTA, and BET measurements. It was found that samples activa…
It is known that chalcogenide glasses, in general, are p-type semiconductors. This is attributed to the following two reasons. (i) The number of electrons excited above the conduction band mobility edge is smaller than the number of holes excited below the valence band mobility edge. (ii) The lifetime of the free hole…
Analytical expressions are derived as a first-order approximation for the elastic displacement fields, including both phonon- and phason-type components, induced by spherical inclusions in icosahedral quasicrystals (IQCs). The phonon-type component obtained is the same as that for a spherical inclusion in conventional…
Upon aging, a collapsed long chain evolves from a crumpled state to a self-entangled globule which can be thought of as a large knot. Swelling of an equilibrium globule in good solvent is a two-step process: (i) fast swelling into an arrested stretched structure with conserved entanglement topology followed by (ii) sl…
Abstract The acid‐catalyzed controlled hydrolytic polycondensation of tetraethoxysilane (TEOS) provided polyethoxysiloxanes with weight‐average molecular weights of 2300–11,700, which depended on the reaction molar ratios of the water, catalyst, and solvent to TEOS. They were soluble in common organic solvents and sta…
Two mechanisms of electrostriction in relaxor ferroelectrics of lead magnesium niobate (PMN) type are proposed. The first is based on the interaction of the soft-lattice polarization and lattice distortions with the charge transfer fluctuations and with the active ion displacements for the localized Nb–O–Nb and O–Nb–O…
Nanocrystalline Ge in SiO2 was synthesized by the reduction of Si0.75Ge0.25O2 with H2, at various annealing temperatures (ranging from 700 to 900 °C), with various H2 partial pressures (100% N2, 6% H2:94% N2, and 100% H2), and for a range of times. Cross-sectional transmission electron microscopy (XTEM) reveals a stro…
Poly(ethylene glycol):poly(acrylate) PEG-g-PA co-polymers were made that inhibited nonspecific protein and cellular adhesion. PEG-g-PA co-polymers were then covalently modified with either cell adhesion peptides or fragments of antibodies to monocyte/macrophage integrin receptors (anti-VLA4, anti-beta(1), anti-beta(2)…
Acoustic and dielectric properties of Pb(Mg1/3Ta2/3)O3 (PMT) and Ba(Mg1/3Ta2/3)O3 (BMT) single crystals with B-site disorder were obtained in a wide temperature range by micro-Brillouin scattering and dielectric spectroscopy. The temperature dependences of both the dielectric constant and the Brillouin shift of the lo…
Polarized Raman spectra of heteroepitaxial (Ba0.7Sr0.3)TiO3 thin film deposited on the (001)MgO substrate have been studied in the broad temperature range from 30 to 1300 K. Our results show that the ferroelectric–paraelectric phase transition is markedly shifted to higher temperatures with respect to the bulk ceramic…
The removal of calcium mineral deposits from metal surfaces is of practical interest for a variety of fields (i.e., food, petroleum, and chemical industries). This study investigated the mechanisms of calcite (CaCO 3 ) dissolution using environmentally benign polyaspartic acid (PASP) under controlled hydrodynamic cond…
White-blue electroluminescent emission with a voltage bias less than 10 V was achieved in rf sputter-deposited amorphous carbon nitride (a-CN) and amorphous silicon carbon nitride (a-SiCN) thin-film-based devices. The heterojunction structures of these devices consist of: Indium tin oxide (ITO), used as a transparent…
The copolymerization of epsilon-caprolactone (epsilon-CL) and d,l-lactide catalyzed by Candida antarctica lipase B was studied. Copolymerizations with different epsilon-CL-to-lactide ratios were carried out, and the product was monitored and characterized by MALDI-TOF MS, GPC, and (1)H NMR. The polymerization of epsil…
Heavy metal oxide glasses containing GeO2 were investigated as potential hosts for 1.48 μm fiber-optic amplifiers because of their low phonon energy. Addition of ⩾10 mol % GeO2 to 0.57PbO−0.25Bi2O3−0.18Ga2O3 (mole fraction) glass provided thermal stability as well as good emission properties. The optimum glass composi…
A thermodynamic approach is used to develop a framework for modeling uranium–niobium alloys under the conditions of high-strain rate. Using this framework, a three-dimensional phenomenological model, which includes nonlinear elasticity (equation of state), phase transformation, crystal reorientation, rate-dependent pl…
Complex structures of carbon nanotubes formed from a conventional carbon arc-discharge method have been revealed by high-resolution transmission electron microscopy (HRTEM). The branching and the droplet growth phenomena observed by HRTEM indicate that the formation and growth of carbon nanotubes from an arc-discharge…