Materials Literature
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It has been demonstrated that self‐concentration quenching mechanisms can be determined from luminescence intensity measurements as a function of activator concentration if the excitation of a powdered phosphor screen is made with the directly and weakly absorbed radiation.
Casting alloys of eutectic composition are of great practical importance. Good microstructural control of these alloys is essential in obtaining the required properties in the cast state. Primary phases present in a eutectic matrix may have either a beneficial or a detrimental effect on these properties. Therefore, th…
Characteristic features of isothermal growth, thickening and melting behaviour of melt grown single crystals of low molecular weight poly(ethylene oxide) fractions are described and discussed in terms of their relevance to basic concepts of polymer crystal growth. In the narrow temperature interval where transition fr…
УСПЕХИ ФИЗИЧЕСКИХ Η Λ У К 535.44 ОПТИКА ХОЛЕСТЕРИЧЕСКИХ ЖИДКИХ КРИСТАЛЛОВ В. А. Беляков, В, Е. Дмитриеико, В. П. Орлов СОДЕРЖАНИЕ 1. Введение 221 2. Кинематическое рассмотрение 224 а) Сечение рассеяния (225).б) Поляризационные характеристики (226).3. Случай нормального падения 227 а) Собственные волны (227).б) Решение…
A detailed NMR, magnetization, x-ray, and neutron-diffraction study is reported for the ${\mathrm{Fe}}_{3\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{Si}$ system over the entire range of Co concentration ($0\ensuremath{\le}x\ensuremath{\le}3.00$). As the Co concentration $x$ is increased, the x-ray measurements indicate t…
Diffusion coefficient of hydrogen in iron has been determined at temperatures between 230 and 300 K. The permeation of hydrogen through the speimen has been measured by an electrochemical method in which alcoholic solutions were used as electrolytes. The experimental permeation curves were analyzed by considering the…
The molecular relaxations in polymeric systems have aroused great interest among polymer scientists during the last decades because these phenomena have profound effects upon many important properties of polymers (e.g., upon mechanical behavior, solid-state reactivity, diffusion, melt rheology, and solution properties…
A field emission electron microscope with highly stabilized gun and illuminating system was developed. Several experiments were made to demonstrate the high performance of the microscope. The brightness of the beam was more than that of the conventional ones, which feature was demonstrated by taking 300 Fresnel fringe…
Abstract An investigation is made of the energy spectra of A and B excitons in CdS by measuring the transmission and reflectivity of very thin highly perfect crystals at 1.8 K. The excited states of both series follow hydrogen‐like series in a good approximation yielding different Rydberg's R = (28 ± 0.4) and R = (31.…
The compositional and structural changes on surfaces that affect the durability of soda-limesilica glasses are discussed. The book begins with a general review of corrosion and weathering phenomena in glass which is followed by a review of the applicable surface analytical techniques (scanning electron microscopy, ene…
Carbon monoxide, oxygen and hydrogen were found to be chemisorbed on dehydrated AgA zeolites. This was investigated in detail using volumetric sorption and temperature programmed desorption techniques. Also i.r. and mass spectrometry were used to characterize the solid and the desorbed molecules.It was found that as a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of electron-withdrawing substituents on the electrochemical oxidation of porphyrinsA. Giraudeau, H. J. Callot, and M. GrossCite this: Inorg. Chem. 1979, 18, 1, 201–206Publication Date (Print):January 1, 1979Publication History Published online1 May 2002Published inis…
Gold has been supported upon SiO2 and γ-Al2O3 using an impregnation technique and HAuCl4 solutions. The severity of the conditions required to effect the reduction/decomposition of the acid to metallic Au upon the support decreased and the activity per unit weight of metal in the hydrogenation of pent-1-ene at 373 K i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDerivatives of heteropolyanions. 1. Organic derivatives of W12SiO404-, W12PO403-, and Mo12SiO404-W. H. KnothCite this: J. Am. Chem. Soc. 1979, 101, 3, 759–760Publication Date (Print):January 1, 1979Publication History Published online1 May 2002Published inissue 1 January 197…
Manganese(III) forms many high spin d4 porphyrins, for which pyridyl, N-methylpyridyl, sulphonic acid and carboxylic acid and carboxylic acid functions act as water solubilising groups. Reduction with dithionite yields the corresponding manganese(II) porphyrin. Both oxidation states have been clearly identified by e.p…
Description The ASTM series on Engineering Dielectrics is devoted to a comprehensive presentation of topics related to electrical insulating materials that concern their dielectric properties, their use, and evaluation for application for electrical power and communication apparatus structures and devices. The first v…
A three-parameter description of optical fiber material dispersion is proposed which fits the available data and reveals the key roles played by bond length, lattice structure, chemical valence, average energy gap, and atomic mass. Using broadly applicable trends in electronic and phonon oscillator strengths, simple e…
It is shown that the mechanism of the electronic conduction due to variable-range hopping in the Anderson localized states gives rise to a large negative magnetoresistance, particularly in the vicinity of the metal-nonmetal transition. This result is mainly caused by an exponential dependence of the hopping rate on th…
Abstract A series of radiation‐grafted hydrogels with water contents ranging from 10% to 90% have been prepared. When evaluated by the vena cava ring test, increasing amounts of adherent thrombus were found in rings with lower graft water contents. Using a baboon arteriovenous shunt evaluation system, platelet thrombo…
Abstract The high‐strength, high‐modulus Kevlar 49 fiber is widely used today because of its superior properties. In this paper, we discuss the fundamental physicochemical nature of the commercial fiber. It is an extended chain polymer, poly( p ‐phenylene terephthalamide), which is highly crystalline. Extensive analys…