Materials Literature
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A new algorithm for the construction of a dense random packing of a binary mixture of hard spheres is presented. The algorithm uses periodic boundary conditions and is capable of handling any binary composition with radius ratio between 1.0 and 2.0. Computed results are relatively insensitive to variations in program…
We present a first-principles approach to deriving the relative energies of valence and conduction bands at semiconductor interfaces, along with a model which permits a simple interpretation of these band offsets. Self-consistent density-functional calculations, using ab initio nonlocal pseudopotentials, allow us to d…
Pure metals were used to prepare Cu(S) and Ag(S) solid solutions at high temperatures; resistivity was measured at 4.2 K. The effects of possible contamination and evolution of the alloys during cooling were examined. the intrinsic resistivities of S in Cu (8.7+or-0.1 mu Omega cm per at%) and in Ag (8.9+or-0.9 mu Omeg…
The authors have investigated the contact charging of polymers by metals, paying particular attention to the variation of charge transfer from place to place on the sample surface, and from one sample to another. For most polymers they find that charge transfer is unaffected by attempts at purification and is much the…
Amino acid sequence studies show that the aliphatic amidase (EC 3.5.1.4) from Pseudomonas aeruginosa PAC142 consists of a single polypeptide chain of 346 residues, giving an Mr of 38,400. The evidence from the amino acid studies is in complete agreement with that deduced from the DNA sequence of the amiE gene. Studies…
The decay of GR1 cathodoluminescence associated with the neutral vacancy in diamond has been studied in the temperature range 10 to 77 K. Exponential decay of the luminescence is only obtained when short (5 ns) widely spaced (10 mu s) pulses are used, yielding a decay time of 3.1 ns in the temperature range studied. I…
Abstract Cellulose linters with starting degrees of polymerization between 100 < DP n < 6000 had been hydrolytically degraded (0.5 M aqueous solution of KHSO 4 , degradation temperature 40°C and 60°C) and the results compared with those obtained in a former study on pure cotton cellulose using the same degradati…
Translational invariance requires that the electron density operator is not diagonal in a Wannier representation. We show that this leads to important terms in the electron-electron interaction Hamiltonian, terms which involve the bond-charge density and which are not included in the widely studied extended Hubbard mo…
We present a new scheme to study the linear response of crystals which combines the advantages of the dielectric-matrix and supercell (``direct'') approaches yet avoids many of their drawbacks. The numerical complexity of the algorithm is of the same order as that of a self-consistent calculation for the unperturbed s…
The vibrational IR spectra of a CsBi(MoO4)2 crystal have been studied in the temperature range 16−300° K in polarized radiation (E‖b, E‖c) in the frequency range 600−1000 cm−1. The influence of structural phase transitions (Tc1 = 135° K, Tc2 = 330° K) on the IR reflection spectra of CsBi(MoO4)2 has been found. By comp…
Abstract In a continuation of previous work (1), the melting and crystallization behavior of the layered oxidized skin on thermally oxidized inner wall surfaces of different high density polyethylene (HDPE) pipes was studied. By hot stage polarized light microscopy on 5 μm thick cross‐sections of the skin, melting was…
The amplitude equation for thermal convective nematic liquid crystals is derived from the equations of motion. The appearance of various patterns (normal rolls, undulations, zigzags, etc.) in different parameter regimes is described in a unified manner. The effect of a horizontal magnetic field is included and the cor…
An improvement of the classical theory of extinction in mosaic crystals is made by starting from the energy transfer equations valid for a general-type crystal according to Zachariasen's [Acta Cryst. (1967), 23, 558-564] classification. Within the assumption that only the integrated intensity of the diffraction peak i…
Both native and regenerated (rayon) cellulosic fibers are potential reinforcing elements in rubbers due to their relatively good mechanical properties, suitable aspect ratio, low cost and low density. The properties of the cellulosic fibers can also be changed fairly easily by chemical treatment. The effects of two tr…
Mercury Hexaselenidohypodiphosphate Hg 2 P 2 Se 6 has been prepared and its vibrational spectrum recorded. The observed frequencies of Hg 2 P 2 Se 6 are assigned on the basis of P 2 Se 6 4- units with C 2h symmetry. DTA data have been determined and interpreted.
Abstract Measurements of the electron spin—lattice relaxation time T 1 and the phase memory time T M of SeO 2 − centres in X‐irradiated single crystals of ferroelastic KH 3 (SeO 3 ) 2 are reported. At temperatures above 11 K the spin—lattice relaxation is governed by a two‐phonon process of optical phonons. Near the p…
Abstract The liquid-phase hydration of acrylonitrile to acrylamide has been examined over various metal catalysts at 75 °C. Five metal elements-Cu, Ag, Fe, Co, and Ni-showed the catalytic conversion of acrylonitrile. The Cu and Ag catalysts gave the acrylamide with a 100% selectivity, while the other metals, Fe, Co, a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe 1,1'-ethylenebis[4-(methoxycarbonyl)pyridinyl] diradical and its photosensitive cyclomersYusaku Ikegami, Takashi Muramatsu, Kaoru Hanaya, Shinji Onodera, Norio Nakayama, and Edward M. KosowerCite this: J. Am. Chem. Soc. 1987, 109, 10, 2876–2880Publication Date (Print):Ma…
Europium Hexathiohypodiphosphate Eu 2 P 2 S 6 with Eu in the oxidation state 2 has been prepared by direct elemental synthesis at high temperatures. Its vibrational spectrum has been recorded. The observed frequencies are assigned on the basis of P 2 S 6 4- units with C 2h symmetry in the crystal in analogy to Sn 2 P…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopic characterization of the .alpha. .dblharw. .beta. crystalline phase transition in poly(butylene terephthalate) and its copolymers with poly(tetramethylene oxide)Eva Dobrovolny-Marand, Shaw Ling Hsu, and C. K. ShihCite this: Macromolecules 1987, 20, 5, 1022–1029P…