Materials Literature
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Photoinduced poling (PIP) is a new technique which allows the room-temperature preparation of guest/host polymer films exhibiting significant polar order for nonlinear optical applications. We report a comparison of this novel technique with the conventional electrode poling procedure performed at the glass transition…
Characterization of the arc-discharge deposits at the cathode from anodes containing yttrium oxide and titanium by transmission electron microscopy and x-ray diffraction shows different results with respect to an encapsulation of the metal carbides into carbon clusters. Yttrium carbide is encapsulated into carbon nano…
The defect properties of as-etched and annealed porous silicon are studied by electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR). The paramagnetic defect observed is closely related to the Pb0 center at the Si/SiO2 interface. In EPR a minimum defect density of 1016 cm−3 is observed…
The steady states of a crack moving in a triangular lattice are calculated and shown to become unstable at a certain velocity.Received 16 June 1993DOI:https://doi.org/10.1103/PhysRevLett.71.2417©1993 American Physical Society
Abstract Adsorption of polymer on filler from bulk is known to result in a partial loss of polymer solubility (“bound rubber”). The existing theories of this phenomenon were critically examined, and the random adsorption model suggested by the author was found to provide the most complete explanation of available expe…
The compressional V p and shear V s wave velocities of diopside (CaMgSi 2 O 6 ), anorthite (CaAl 2 Si 2 O 8 ), and grossular (Ca 3 Al 2 Si 3 O 12 ) glasses and liquids have been measured by high‐resolution Brillouin spectroscopy up to 1200 or 1400 K. For all three materials, marked breaks in the wave velocity‐temperat…
We used exact diagonalization of small clusters and exact results in various limits to determine the phase diagram and the critical exponents of the one-dimensional (1D) U-V model at quarter-filling. We found an instability of the Luttinger liquid to a charge density wave (CDW) insulator across a boundary going from (…
Abstract Films of a commercial poly(ether urethane), Pellethane 2363‐80AE, were prepared through solvent casting from dimethyl formamide. The films were grafted with poly(ethylene glycol) (PEG) by a two‐step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate in toluene in the…
Results are reported for a molecular dynamics simulation study of a flexible model mesogen composed of seven tangential spheres. We follow the ‘rattling spheres’ method by which bonded atoms are constrained to lie within narrow potential wells. The dynamics of the system is that of a hard sphere fluid with added const…
The Gay-Berne potential is proving to be of considerable value in computer simulation studies of liquid crystals. However, the parameters employed in the potential were chosen by comparison with that for a line of four Lennard-Jones centres; they may not, therefore, be appropriate for mesogenic molecules. To see if th…
Abstract Epoxidized natural rubber (ENR) reacts with surface oxygen groups of carbon black. The higher the concentration of these groups, the higher the intensity and the extent of reaction and the better the reinforcing ability of the black. Oxidized furnace blacks and channel blacks, which are known to have high qua…
The function of a flexible loop (loop 6) in the alpha-subunit from the tryptophan synthase alpha 2 beta 2 bienzyme complex has been investigated utilizing rapid-scanning (RSSF) and single-wavelength (SWSF) stopped-flow spectroscopies. Loop 6 is an extended sequence of residues which connects beta-strand 6 with alpha-h…
Abstract The generalized suspension viscosity equation utilized in this study was evaluated with both a packing fraction, φ n , and a particle interaction coefficient, σ, as a function of suspension blend composition, f 2 T . The estimation of the packing fraction, φ n , in turn, required the further elucidation of th…
Deletion of 13 amino acids from the carboxyl terminus of staphylococcal nuclease (WTSNase delta) results in a denatured, partially unfolded molecule that lacks significant persistent secondary structure but is relatively compact and monomeric under physiological conditions [Shortle & Meeker (1989) Biochemistry 28, 936…
Abstract The preparation of membranes of nylon 4,6 by diffusion‐induced phase separation (DIPS) using formic acid as a solvent and water as a nonsolvent was studied. Nylon 4,6 is a semi‐crystalline polymer; phase separation from a solution can occur by solid–liquid (s–l) de‐mixing as well as by liquid–liquid (l–l) dem…
Optical measurements (photometry and ellipsometry) were performed under oblique incidence from 0.03 eV to 6 eV on silver/silica (Ag/SiO 2 ) multilayers prepared by magnetron sputtering. Around 3.79 eV, the plasma frequency of Ag, and 0.154 eV and 0.133 eV, the longitudinal and transverse optical frequencies of SiO 2 ,…
The recently discovered high-intensity thermoluminescence (TL) emission in Al 2 O 3 doped with Cr and Ni is analysed more deeply by measuring the effects of x-ray irradiation on the optical absorption in parallel with the TL process, together with the effect of optical bleaching. It is proposed that the high-intensity…
The effects of applied transverse field on magnetic properties (transition temperature, compensation temperature and magnetization) of a disordered ferrimagnetic binary alloy which can exhibit two compensation points are examined. It is proposed that the application of a weak transverse field to the sample may be a us…
We present a microscopic theory of the transition to and properties of the amorphous solid state of a system of vulcanized (i.e., randomly crosslinked) macromolecules. Our approach invokes a variational hypothesis for the random static density fluctuations characterizing this solid state. The variational parameter is…
We report on picosecond laser-induced damage experiments that were carried out on a natural type-IIa diamond and a thick specimen of high-quality chemically vapor-deposited (CVD) diamond. In conjunction with earlier measurements performed elsewhere on an ‘‘optically thick’’ single crystal, it is shown that for spot si…