Materials Literature
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Using semiempirical molecular-orbital calculations, we have obtained the principal transfer integrals which parametrize the band structure of tetramethyltetraselenafulvalene salts [${(\mathrm{TMTSF})}_{2}X$] [$X=\mathrm{Cl}{\mathrm{O}}_{4}, \mathrm{Re}{\mathrm{O}}_{4}, \mathrm{FS}{\mathrm{O}}_{3}, \mathrm{P}{\mathrm{F…
The intrinsic microwave absorption coefficient $\ensuremath{\beta}$ of alkali halides is well explained by lifetime-broadened two-phonon difference processes, in contrast to energy-conserving two- and three-phonon processes as previously thought. A simple closed-form expression for $\ensuremath{\beta}$ with no adjusta…
We discuss the nature of polaron excitations in two models of current interest in the study of quasi-one-dimensional materials: the coupled electron-phonon and molecular-crystal models. Using for definiteness parameters appropriate to trans-${(\mathrm{CH})}_{x}$, we show that, although qualitatively very similar, the…
We have investigated the peroxy-radical defect in glassy Si${\mathrm{O}}_{2}$ by means of MOPN, a semiempirical molecular-orbital program, applied to a cluster of atoms chosen to simulate the defect. Our calculations are consistent with important features of Griscom's model of the defect as a perturbed ${\mathrm{O}}_{…
Based on well known mechanisms, the authors set up a system of coupled nonlinear rate equations for the densities of three types of dislocations, namely, the mobile, the immobile and those with clouds of solute atoms, and for the load sensed by the load cell. For a range of values of the parameters, these equations ad…
When 'The Biochemistry of the Nucleic Acids' first appeared in 1950, under the authorship of the late J.N. Davidson, it was a slim book of 163 pages that slipped easily into a coat pocket.It was recognised immediately as a valuable text, that filled an important gap, and was a suitable book for undergraduates and juni…
Tracer diffusivity of Na, K, Rb, Cs, Ca, Sr, Ba, Eu, and Ce has been measured in natural and dehydrated obsidians in the range 300°–1300°C, 0–4 kbar, using radiotracers and an etching technique. The results complement and extend previous results on similar material. Diffusivity ranging from 10 −16 to 10 −7 cm 2 /s hav…
Abstract Zur Herstellung des ECD‐ Elementes (electrochromic display) wurde eine dünne Schicht von TiO 2 (Anatas) auf ICG‐Substrat (In 2 O 3 ‐coated glass) erzeugt.
The excitation of fluorescently labeled polymer coils by shallow optical evanescent waves permits measurement of the local monomer solute concentration in the vicinity of a nonadsorbing wall over controlled, submicroscopic distances. The existence of a depletion layer at the solid-solution interface is thus demonstrat…
This paper describes a Monte Carlo study of the thermal conductivity and impurity transport in a tokamak with an optimized bundle divertor configuration. This configuration has been designed to obtain the best plasma performance. When collisions and electric fields are included, the thermal conductivity was found to b…
Article A new method for determining the lattice parameters from powder patterns of orthorhombic crystals was published on December 1, 1982 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 161, issue 1-4).
Na2O·3SiO2 glasses with up to ≈12 wt% water were prepared under high-pressure, hydrothermal conditions and their densities, glass transition temperatures, mechanical properties, electrical conductivities, sodium diffusion coefficients and radiation effects were measured. The density, glass transition temperature, hard…
In this paper, the optical and some other physical properties of fluorophosphate glasses in binary systems containing Al(PO3)3 and the influence of various fluorides on the properties of glass with low Al(PO3)3 content have been studied. The positions of low Al(PO3)3 content glasses in nd∼ν diagram have been plotted a…
Dielectric relaxations were observed in beds of dextran gel beads preconditioned with different salt solutions and subsequently dispersed in deionized water in a frequency range of 10 kHz to 1 MHz. The relative permittivities and electrical conductivities of the gel beads were evaluated from the observed relaxations u…
Abstract Polymers under discussion can be represented by [CH 2 ) n R] p where R is CH 2 , CF 2 , O, S or CH = CH; and where n can vary from 0 to ∞. The copolymer, P(ethylene‐alt‐TFE) is also included. These polymers tend to be highly crystalline with resultant confusion about their Tg and hence their Tg/Tm values and…
Abstract An outstanding achievement of organopolymer chemistry during the past two decades has been the successful development of high‐temperature‐resistant heteroaromatic polymers. The present account makes use of the data available on the synthesis, properties and applications of a relatively small yet typical group…
Changes of density which occur naturally in phase change problems introduce movement of bulk material. It is customary in analyzing such problems to ignore this unpleasant complication and consider the densities to be equal. But for one-dimensional problems the complexities introduced by this bulk movement can easily…
A bstract Source strength of an airgun array may be increased by: utilizing higher pressure, increasing total array volume, employing more guns, improving gun efficiency. One measure of gun efficiency is “specific source strength”, P a *, defined as source strength per unit quantity of air used. Typical units are MPa…
Résumé Des lizardites substituées (Mg,Fe,Ni) 3 Si 2 O 5 (OH) 4 ont été étudiées par spectrométrie en réflectance diffuse de 340 à 2500 nm, de manière à déterminer l'environnement de Mg 2+ , Ni 2+ et Fe 2+ , en particulier la symétrie des sites et les distances métal-ligands. L'examen de la structure de la lizardite se…
Abstract Low temperature Guinier photographs of Na 3 NO 3 ( + 20° → - 140 °C) indicate two phase transitions to M-Na 3 NO 3 and T-Na 3 NO 3 at - 53±3°C and - 122±3°C, respectively. During the phase transitions the main structural features (NO 2 -[ONa 3 ]: antiperovskite type of structure) remain unchanged. The dynamic…