Materials Literature
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Ab initio calculations predict that Be is a shallow acceptor in GaN. Its thermal ionization energy is 0.06 eV in wurtzite GaN; the level is valence resonant in the zincblende phase. Be incorporation is severely limited by the formation of Be_3N_2. We show however that co-incorporation with reactive species can enhance…
perovskites (R = rare earth) provide a remarkable opportunity to study the relationship between structural and physical properties since, by moving along the 4f rare earth series, the evolution of several transport and magnetic properties can be nicely correlated to the steric effects associated with the lanthanide co…
We have developed a novel cryostat in which glassy states of molecular substances are formed by deposition of their vapor on a cold substrate. The glassy samples are subjected to in situ inelastic neutron scattering experiments. By the use of this cryostat, the glassy state of propylene(CH2=CHCH3) prepared at 20 K was…
The process of microphase separation in diblock copolymer/homopolymer blends is studied both theoretically and experimentally for an asymmetric diblock copolymer and for homopolymer concentration less than 25%. The degree of polymerization of the added homopolymer (Nh) covered all possible cases; N≈Nh, N>Nh, an…
The polymer segment distribution is shown to obey the Laplace equation for a suspension of small protein spheres and semidilute polymer. The depletion interaction is computed at all protein concentrations by introducing void distributions. Within a linear response Ansatz for the solution to the Laplace equation, the a…
We report the phase coexistence properties of polarizable Stockmayer fluids of reduced permanent dipoles |m0*|= 1.0 and 2.0 and reduced polarizabilities α*= 0.00, 0.03, and 0.06, calculated by a series of grand canonical Monte Carlo simulations with the histogram reweighting method. In the histogram reweighting method…
Highly transparent and conductive polyaniline-cellulose acetate composite films were cast from m-cresol solutions of protonated polyaniline and cellulose acetate. The following polyaniline protonating agents were used: camphor sulfonic acid, phenylphosphonic acid, dibutyl phosphate, and dioctyl phosphate. The films we…
We have used high resolution stimulated Brillouin gain spectroscopy to monitor the nonequilibrium relaxation dynamics of supercooled glycerol near its glass transition temperature. After a temperature quench from 192.4 to 179.8 K, the Brillouin frequency shift increased over a period of 17 d from 16.877±0.005 GHz to 1…
We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting pol…
Calorimetric, mechanical, and thermomechanical properties have been measured on starch films with various glycerol/water contents. For calorimetric measurements, a continuous decrease in Tg was observed as glycerol increases from 0 to 25%. Mechanical properties exhibit a minimum of elongation at break for glycerol con…
The performance of high-voltage solid insulators that are used to bridge vacuum gaps is frequently limited by surface flashover. An important characteristic of the flashover process under DC conditions is that it occurs `spontaneously', namely without warning and any obvious external triggering agents. Significantly,…
and thin-film capacitors have been grown on (001) and MgO(001) substrates by off-axis laser deposition. Reflection high-energy electron diffraction (RHEED) and pole figures have revealed the epitaxial growth of the and thin films. The films with metal electrodes show only weak ferroelectric properties. Using as electr…
The optical constants and average thickness of metal - chalcogenide glass films of chemical composition , with x = 5, 10 and 15 at.%, are very accurately determined by a novel method, based only on the transmission spectra at normal incidence, measured over the 400 - 2200 nm spectral range. This useful optical method…
We extend our previous first-principles theory for perovskite ferroelectric phase transitions to treat also antiferrodistortive phase transitions. Our approach involves construction of a model Hamiltonian from a Taylor expansion, first-principles calculations to determine expansion parameters, and Monte Carlo simulati…
Optical detection and spectroscopy of single molecules and single nanoparticles have been achieved at room temperature with the use of surface-enhanced Raman scattering. Individual silver colloidal nanoparticles were screened from a large heterogeneous population for special size-dependent properties and were then use…
Abstract New and updated, this second edition of Protein Structure presents electrophoretic, chromatographic, and spectrophotometric techniques as well as including new chapters on the relatively sophisticated methods of mass spectrometry and ultracentrifugation. The emphasis is not on the technical aspects of the ins…
One-dimensional conductors are a long-standing topic of research with direct applications to organic conductors and mesoscopic rings. The discovery of the ceramic high-temperature superconductors has revitalized the interest in low-dimensional charge and spin fluctuations of highly correlated electron systems. Several…
Abstract The stability of proteins, especially enzymes, has long been a practical concern (1), because this is usually the factor that most limits their usefulness. There are two very different aspects of protein stability. One is the chemical stability of the covalent structure, which involves covalent changes and is…
The effects of mobility of small islands on island growth in molecular beam epitaxy are studied. It is shown that small island mobility affects both the scaling and morphology of islands during growth. Three microscopic models are considered, in which the critical island sizes are $i^*=1,2$ and 3 (such that islands of…
Abstract The commonest means of laboratory evaluation/screening of scale inhibitors for oilfield applications is by conducting scale inhibition jar tests. This paper focuses on several aspects concerning barium sulphate scale inhibition jar tests and highlights three particular factors which may influence the test out…