Materials Literature
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We describe reversible holographic effects in azo-dye doped liquid crystals. Surface-stabilized holograms are recorded at 514 nm using beams polarized parallel to the molecular director of the liquid crystals. While these holograms persist for several hours in the dark, complete erasure is achieved in a few seconds by…
New lines in the low temperature luminescence spectra of lightly aluminum doped p-type films of 3C, 6H, and 4H SiC are identified and associated with the recombination of a neutral aluminum acceptor four particle bound exciton complex.
We studied the change in electrical conductivity of deposits from focused electron beam induced dissociation of W(CO)6 for different exposure conditions. Lines were deposited by scanning repeatedly to build up the same total electron dose; with different electron doses per scan, resistance differences of more than one…
Hall-effect and resistivity measurements were performed on simultaneously deposited B-doped homoepitaxial and polycrystalline diamond films, as well as a (100)-oriented type-IIb natural diamond crystal, over a temperature range of 140–600 K. At 298 K, the respective Hall mobilities for the homoepitaxial and polycrysta…
In a Langmuir monolayer of NBD-stearic acid, long rods (\ensuremath{\sim}1 mm long, \ensuremath{\sim}20 \ensuremath{\mu}m wide) of a two-dimensional solid phase are obtained at the liquid-solid phase transition. A rod bent in the plane of the water under the effect of a bending stress breaks after a clearly defined de…
The kinetics of photoinduced defect formation in high-purity silicas has been studied by femtosecond transient absorption spectroscopy in the visible and ultraviolet. Band edge two-photon excitation produces singlet excitons which decay in 0.25 ps into defects with the absorption spectra of nonbridging oxygen hole cen…
Abstract Starch‐ g ‐poly(methyl acrylate) copolymers (S‐ g ‐PMA) containing 10, 30, 46, and 58% PMA, by weight, were prepared by ceric ammonium nitrate‐initiated polymerization of methyl acrylate onto granular cornstarch. Graft copolymers were extrusion‐processed through a strand die with water contents of 10 and 30%…
Abstract The effect of uniaxial and biaxial film‐processing parameters on the orientation of the phenyl ring in the crystalline and amorphous phases has been evaluated using a variety of techniques. It has been demonstrated that the total phenyl ring orientation factor (PROF) measured from refractive indices can refle…
Tyrosyl ring motions in alpha-lytic protease were investigated by solid-state deuterium nuclear magnetic resonance (NMR) spectroscopy in lyophilized enzyme powder, in powder suspended in organic solvents, and in aqueous crystals. Ring flipping rates were determined by examining deuterium quadrupole echo line shapes. O…
The synthesis of poly(phenylcarbyne), one of a class of carbon-based random network polymers, is reported. The network backbone of this polymer is composed of tetrahedrally hybridized carbon atoms, each bearing one phenyl substituent and linking, by means of three carbon-carbon single bonds, into a three-dimensional r…
We have thus far dealt with the resistance to crack propagation at opposite extremes of material representation, continuum solid and atomic lattice. It is now appropriate to investigate the problem at an intermediate level, that of the microstructure . By ‘microstructure’ we mean the compositional configuration of dis…
This is an advanced text for higher degree materials science students and researchers concerned with the strength of highly brittle covalent–ionic solids, principally ceramics. It is a reconstructed and greatly expanded edition of a book first published in 1975. The book presents a unified continuum, microstructural a…
A simple effective-medium approach is used to study anisotropy properties of the electrical resistivity in the quasicrystalline decagonal Al–Mn system.
Molecular dynamics simulations of computer have been performed on the local structure and bond orientation order of liquid metal Pb at 623 K. Results show that, at point near melting temperature, the local structures of liquid metal Pb show cubic symmetry, and the long-range correlation of this symmetry is weak.
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Article Temperature dependence of the silver distribution in Ag2MnP2S6 by single crystal X-ray diffraction was published on June 1, 1993 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 203, issue 1-2).
One of the main defects in the self-frequency doubling crystal of Nd 3+ -doped YAl 3 (BO 3 ) 4 (NYAB), which may be the key factor to influence the crystal performance, is the growth zone boundary that has been identified by means of x-ray diffraction topography. The characteristic boundary is formed usually by the ba…
An activity geared toward a course where experiments are designed to investigate the preparation of materials, the properties essential to understanding their formation, and the optimization of their application.
We studied the influence of substrate defects on the morphological and transport properties of Y1Ba2Cu3O7−x high Tc superconducting thin films. The substrate defects were characterized by dispersive and nondispersive cathodoluminescence in the scanning electron microscope. The morphology of the films was studied by th…
It is known that the chicken flank somatopleure also has a limb-forming potential at early stages of development, but loses this potential later. Molecular changes during this process is, however, not well known. We obtained a monoclonal antibody which reacts to the flank somatopleure, but not to the wing bud, the leg…