Materials Literature
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Scatterings of near-zone-boundary phonons by isotopic disorder in diatomic GaAs InSb crystals are studied theoretically. In multiatomic lattices the scattering rate depends importantly on the vibrational amplitudes of constituent atoms. We find that the wave-vector dependences of these amplitudes, which are predicted…
We present a new method of electrochemical polymerization of poly(thiophene) using dithiophene as the starting material, from which we obtain a high-quality film with a sharp interband absorption edge. An in situ study of the absorption spectrum during the electrochemical doping process has been carried out. In the di…
Photoemission, optical-absorption, and isochromat spectra of NiO and ${\mathrm{NiCl}}_{2}$ are studied theoretically by the consideration of configuration interactions within the metal-ligand cluster. It is shown that the satellites in the valence-band photoemission spectra contain significant ${d}^{7}$ final-state co…
We present the results of tight-binding band-structure calculations on a deformable polypyrrole chain, as a function of doping. The states which are produced are polarons and bipolarons whose excitation spectrum explains the optical-absorption data.
Three structural models of amorphous carbon with differing percentages of threefold- and fourfold-coordinated atoms were constructed and analyzed, along with a purely four-coordinated amorphous Ge model which was scaled to diamond bond lengths. The radial distribution function and interference function, $F(k)$, of the…
A capstan method is used to measure the fibre-fibre and fibre-metal coefficients of friction of single polyester staple fibres. Tests have been conducted over a range of relative speeds (0.03-290 m min -1 ), normal loads (0.3-16 mN), and against two stainless steel pins of surface roughness 0.11 and 0.28 mu m RA. The…
The preparation of suitably large protein single crystals is essentially the rate-determining step of protein x-ray structure determinations. Attempts to produce single crystals with two model compounds-beta-galactosidase and lysozyme-under conditions of microgravity were successful. Crystals formed by salting out fro…
Thermally induced surface-driven convection (thermal Marangoni convection) was investigated in the Spacelab 1 microgravity environment. The configuration studied is related to the floating-zone technique used for crystal growth.
The majority- and minority-spin states of the exchange-split virtual bound state of Mn impurities in Cu and Ag are studied with high-resolution photoemission and bremsstrahlung isochromat spectroscopy. The exchange splitting is found to be close to the atomic value. The majority-spin state is strongly hybridized with…
Abstract Applying Hill’s self-consistent method to finite elastic-plastic deformations, we estimate the overall moduli of polycrystalline solids. The model predicts a Bauschinger effect, hardening, and formation of vertex or corner on the yield surface for both microscopically non-hardening and hardening crystals. The…
The 1,4‐β‐D‐glucan cellobiohydrolase I (CBHI) from Trichoderma reesei was labelled with 4–6 nm gold particles. This CBHI‐gold complex still retains 60% of the original CBHI activity and allows good visualization of the enzyme adsorbed at the surface of cellulose mirofibrils or microcrystals. The main features of the a…
An internal photoemission experiment which yields the energy-dependent momentum-and energy-loss rates of hot electrons is designed. The results on solid hydrocarbon films are analyzed in terms of the appropriate Boltzmann equation. Band mobilities are obtained for hot electrons. Their energy-loss rate has a maximum at…
The (heretofore unknown) crystal structure of lithium at low temperature is identified to be close-packed rhombohedral $9R$. The stacking order of the hexagonal layers is $ABCBCA\ensuremath{-}CAB$, a nine-layer repeat sequence. There are three atoms per primitive rhombohedral cell, and nine in the (nonprimitive) hexag…
An investigation has been carried out to study changes in shape on aging in plastic deformed Ag-Pd-Au-Cu alloys. The changes in shape were measured in order to establish a relationship to the aging heat treatments. Their microstructure was observed in order to clarify this phenomenon at the same time. They were also i…
In this paper we briefly discuss the operation of the silicon intensified target (SIT) vidicon, describing what we conclude to be the most important properties of the detector. We provide experimental evaluation of the SIT vidicon characteristics, including two-dimensional image fidelity, channel-to-channel and pixel-…
Thermal conductivity (A) data for two dense Cr 2 O 3 samples are reported. The results, which span the temperature range 270 to 360 K, show an inflection near the Neel transition temperature, 308 K. An analysis shows that the slope of the higher‐temperature portion of the λlD −1 −T curve is about what would be expecte…
The effect of several chemical and physical treatments for PbTe(100) surface cleaning was investigated by XPS. Etching with a (NH4OH+H2O2) solution shows a remarkable contrast to etching with acid, the first one being suitable to eliminate carbon contamination. The combination of the (NH4OH+H2O2) etching, heating and…
Abstract Eine Apparatur zur Untersuchung der Spannungsrißkorrosion von Stahlen in flüssigem Ammoniak unter definierten elektrochemischen Bedingungen wurde aufgebaut. Ein Rechner steuerte den Versuchsablauf und registrierte die Meßdaten. Die dazu nötigen Programme wurden entwickelt. Versuche mit Rundproben aus Schweißs…
Abstract The voltage lifetime of a poly(ethylene terephthalate)/glass composite is measured for two different orientations of short fiber with respect to the applied electric field (perpendicular and parallel). The difference in the voltage lifetime between two configurations is attributed to the microstructural featu…
Summary Monitoring of microbial corrosion is always difficult because of the sessile nature of bacteria and the lack of meaningful correlation between routine bacteria counts and bacterial activity. This problem is further aggravated in a large oilfield water system because of size and sampling difficulties. This pape…