Materials Literature
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A theoretical approach for the prediction of the growth forms of crystals is presented on the basis of the kinetics of crystal growth. To describe the growth morphology of crystals, the more precise relations between the relative growth rate of the crystal faces {hkl} ${\mathit{R}}_{\mathit{hkl}}^{\mathrm{red}}$ and h…
Abstract The homopolymerization of butadiene in the presence of a rare earth‐containing catalyst system was examined at 60°C. The catalyst system consists of neodymium octanoate, diethylaluminium sesquichloride and triisobutyl aluminium in n‐heptane. This catalyst shows high activity also at low polymerization tempera…
Abstract— In order to study the cyclic stress‐strain behaviour under variable amplitude loading in terms of dislocation glide character and microstructure, various metals and alloys were cyclically loaded in single‐step tests and in an incremental step test (IST). The cyclic stress‐strain curves (CSS curves) which cor…
Incoherent imaging in the scanning transmission electron microscope (STEM) provides enhanced image resolution, strong Z-contrast, and the capability for direct inversion to the projected structure. It relies on the use of a high angle annular detector to average phase correlations between diffracted beams, while the c…
Beryllium oxide(BeO)-doped (0.3, 0.6, 0.9, 1.2 and 13.6 wt%) UO2 pellets were fabricated to evaluate the effects of BeO precipitate shape on thermal conductivity. Precipitate distributions were of two types: BeO precipitated almost continuously along a grain boundary (designated BeO continuous type) and spherical BeO…
The Y-12 plant at Oak Ridge, Tennessee, produced nuclear materials for the U.S. government's nuclear weapons program beginning in 1943. Workers at Y-12 were exposed to low dose, internal, alpha radiation and external, penetrating radiation, as well as to beryllium, mercury, solvents, and other industrial agents. This…
Oxidation studies have been performed on titanium dibor‐ide (TiB 2 ) powders, from room temperature up to 900°C. The studies were performed at low partial pressures of oxygen, at 10 and 0. 05 ppm of O 2 in argon, simulating furnace atmosphere with flowing neutral gas of medium and high purity, and in air. It has been…
Thermodynamic calculations were performed to analyze the simultaneous oxidation of BN and SiC. The results show that, with limited amounts of oxygen present, the formation of SiO 2 should occur prior to the formation of B 2 O 3 . This agrees with experimental observations of oxidation in glassceramic matrix composites…
Abstract Activated carbon was impregnated with a metal halide, and adsorption and desorption characteristics of CO on the carbon were measured by fixed‐bed runs. It was found that the impregnation of PdCl 2 or CuCl effectively increases CO absorption. PdCl 2 /CuCl‐impregnated carbons were characterized by N 2 adsorpti…
Abstract Three different models have been reported previously to describe the kinetics of the transformation of smectite to illite (Pytte 1982; Velde and Vasseur 1992; Huang et al. 1993). In order to evaluate the general utility of these models to calculate the timing and extent of this transformation, each model was…
Galvanostatic reduction of and sputter‐deposited thin films was investigated as a model for reduction of the passive film on iron. X‐ray absorption near‐edge spectroscopy was used to perform in situ measurements of the valence state and dissolution (thinning rate) of the films during reduction. In borate buffer, the r…
The modABCD operon, located at 17 min on the Escherichia coli chromosome, encodes the protein components of a high affinity molybdate uptake system. Sequence analysis of the modA gene (GenBank L34009) predicts that it encodes a periplasmic binding protein based on the presence of a leader-like sequence at its N termin…
Effect of oxygen concentration in the sputtering ambient on the microstructure, electrical and optical properties of radio-frequency magnetron-sputtered indium tin oxide films , Wen-Fa Wu, Bi-Shiou Chiou
A new parameterization is defined for the quantitative description of octahedral tilting in orthorhombic and tetragonal perovskites. It contains six parameters, s 1 , s 2 , s 3 , θ x , θ y and θ z . s 1 , s 2 and s 3 refer to the lengths of the lines or `stalks' joining pairs of opposite octahedral vertices, and θ x ,…
Electrical impedance measurements have been made in the frequency range 5 Hz to 10 MHz in pure poly(ethylene oxide) having a molecular weight of 600,000 from 12 K nearly up to the melting point of the crystalline phase (about 330 K). A pronounced relaxation peak in the dielectric loss and a corresponding step in the d…
Abstract In monolith reactors with catalytic washcoat, intraphase diffusion effects have often been underestimated. This paper presents numerical simulations of diffusion/reaction in the washcoat of a catalytic monolith reactor. The problem is solved in two dimensions for the washcoat geometry obtained in a 1‐mm squar…
The rate of capillary rise of a liquid into a porous medium made up of consolidated particulates is analyzed. The infiltration distance is parabolic in time and can be modeled using the Washburn analysis. The effective pore radius is measured to be one to two orders of magnitude smaller than the particle size, particl…
The magnetic properties and field-dependent specific heat of melt-spun amorphous RE70TM30 (RE=Gd, Tb, Dy, Ho and Er; TM=Fe and Ni) and Gd65Co35 alloys were investigated as potential magnetic refrigerants. Essentially zero magnetic hysteresis was observed in all the Gd–TM alloys at temperatures from 5 K up to the order…
In the present bond-valence concept the bond-valence parameter r o is treated as constant for a given pair of atoms, and it is assumed that the bond valence s ij is a function of the corresponding bond length D ij , and that the atomic valence is an integer equal to the formal oxidation number for V i derived from sto…
Sodium sulfate, Na2SO4, has been reported to exist in five polymorphous forms labelled I–V. Structure analysis has been reported on three of the polymorphs and thermal analysis on all of them. The system has been reinvestigated by differential scanning calorimetry (DSC) and by X-ray powder diffraction at several tempe…