Materials Literature
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The nucleation of microcellular foams in amorphous thermoplastics has been performed by supersaturation with gas at an elevated temperature. Pressure and temperature are then carefully reduced in the vicinity of the glass transition temperature of the material. The result is a foam structure with cells on the order of…
Abstract Charging of the specimen under electron beam irradiation is a common problem in scanning electron microscopy (SEM). It results in unstable imaging conditions and a loss in resolution due to defocus of the beam. In addition, it can cause permanent changes in some specimens from translocation of mobile ions und…
Tilings and Patterns: An Introduction presents in convenient paperback form the first half of Tilings and Patterns. Omitting the more specialized material of the earlier volume, this abbreviated edition make's the authors' contributions to tiling theory and its practical applications accessible to a wide audience. Til…
The authors evaluate the available starting methods for motors above 3000 HP, focusing on technical and economic aspects. The following starting schemes are discussed: direct online, reactor, autotransformer, capacitor, captive transformer, and frequency start. A review of the network conditions that favor a particula…
Ellipsometry has been used to characterise the growth of polyaniline films on platinum and gold electrodes by potential cycling. Analysis of the time evolution of the ellipsometric parameters allowed continuous monitoring of the growth process, and subsequent measurements of the changes in optical properties during ox…
The electrostriction of the cubic blue phases was investigated in the well known mixture CB15/E9. The results for BPI prove that a decrease of the lattice constant in the field direction with increasing field strength can occur in a system with positive dielectric anisotropy. In agreement with recent theoretical consi…
Morphological characteristics of the orthorhombic martensite in a Ti–Ni–Cu shape memory alloy have been investigated and the following have been found:(1) In the cubic (B2) to orthorhombic transformation of the Ti–Ni–Cu alloy, no lattice invariant shear is needed. This is due to the fact that one of the principal dist…
Coated particles embedded in graphitic elements are the fuel for the High-Temperature Reactor (HTR). Experimental investigations of the performance of particles at extremely high temperatures have been conducted to achieve an understanding of coating failure mechanisms and to establish the data base for safety and ris…
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Measurements are presented of increased harmonic currents in a 500 kV power system due to geomagnetically induced currents (GIC). The measurements were made of 60 Hz, 120 Hz, and 180 Hz currents and GIC in a 1200 MVA transformer. The recorded increases in the harmonic currents at times of GIC are consistent with compu…
On the basis of Landau-de Gennes-theory it is demonstrated that point defects in nematic liquid crystals may have a biaxial nonsingular core. From this result a critical diameter is derived for linear topological solitons in nematics. Solitons of smaller diameter can relax to the uniform nematic state without energy b…
The basic parameters of screen printing are discussed, and an analytical model of the screen printing process is introduced. The ink roll in front of the squeegee is treated as a pump generating, close to the squeegee edge, high hydrostatic pressure which injects ink into the screen meshes. The shearing of the ink, th…
The collagens of normal and end-stage alcoholic cirrhotic human liver were investigated. Mild conditions of pepsin digestion were employed to preserved the more pepsin sensitive type IV collagen molecules while increasingly more harsh conditions were used which solubilized the type I and type III hepatic collagens. Th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of (.mu.-dithio)bis(tricarbonyliron), an inorganic mimic of organic disulfides. 3. Reaction with low-valent metal compounds and some interesting isolobal analogies involving the productsMartin Cowie, Roger L. DeKock, Timothy R. Wagenmaker, Dietmar Seyferth, Richard…
The interrelationships between the corrosion rate of pipeline steel and soil parameters have been investigated under both controlled laboratory and natural outdoor conditions. Both defect-(holiday)-free, polyethylene-coated samples and samples with intentional 1-cm2 holiday areas were studied. By using electrochemical…
Cocondensation of atoms of the lanthanide elements with 1,3,5-tri-t-butylbenzene gives the thermally stable bis(η-arene)lanthanide(0) sandwich compounds for the lanthanides Nd, Tb, Dy, Ho, Er, and Lu, thermally unstable complexes for La, Pr and Sm, and unisolable materials for Ce, Eu, Tm, and Yb; a simple bonding mode…
On montre que les structures des verres de borate de Cs, Rb et K, de compositions couvrant les larges domaines de formation du verre, peuvent etre systematiquement etudiees par spectrometrie Raman
The development of polyimide films in Japan is discussed. The chemical structure of the films and their polymerization mechanisms are described. Types of polyimide films are identified, and their characteristics are examined. Special attention is given to their thermal and chemical properties and their radiation resis…
Abstract Quantitative determination of the weight percentages of mineral phases in rocks and soils challenges theorist and analyst alike. Although precision – analytical reproducibility – is often described in great detail, few, if any, commercial laboratories or published methods say much about accuracy – the approac…
The direct oxidation of methane into methanol has been studied in a flow microreactor. The effects, on the selectivity to methanol, of the type of reactor, temperature, pressure, residence time, oxygen content, gas mixing and dilution, have been investigated. The results show that at relatively low pressures the use o…