Materials Literature
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The elastic problem in two-dimensional percolation is investigated on a hierarchical lattice, in the context of Cosserat elasticity (or granular elasticity). For this regular fractal, the exponent of elastic moduli ($\frac{T}{v}$) is slightly smaller than the expected value ($\frac{t}{v}+2$) deduced from the conductiv…
Distribution of doping cations between A and B sites of perovskite ABO3 structure obeys certain conditions derived in terms of energy. These can be applied to predict semiconducting BaTiO3-based compositions, to account for yet unexplained anomalies in concentrational dependencies of electrical resistivity and Curie t…
Dislocation structures in fatigue were investigated with special consideration given to the compatibility of the macroscopic observation by an optical microscope and the microscopic observation by a transmission electron microscope (TEM). First, previous works are reviewed from this point of view, that is, the compata…
The polypeptide produced by expressing a chemically synthesized gene coding for the amino-acid sequence of T4-lysozyme has been crystallized and subjected to X-ray diffraction. The crystal structure has been refined to a standard R-factor of 0.191 for data between 8 and 2 A resolution. The refined model is essentially…
We are probing the determinants of catalytic function and substrate specificity in serine proteases by kinetic and crystallographic characterization of genetically engineered site-directed mutants of rat trypsin. The role of the aspartyl residue at position 102, common to all members of the serine protease family, has…
The effect of Zr addition to FeTi on the initial hydriding process, the pressure-composition isotherms and the microstructure was investigated. The partial substitution of Zr (1∼15 at%) for Fe, Ti or both enhanced the activation of FeTi and it hydrided at 303 K after a short incubation time without any heat treatment.…
Diatom shells are intricate structures made by single algal cells with a spacing between parts of about 0.1 mu m. They appear to be formed by instabilities in diffusion-limited precipitation of amorphous, colloidal silica. The patterns are apparently modified by surface diffusion during their formation. They present a…
The ac conductivity of nickel oxide‐metal composites has been investigated as a function of the nature and concentration of the metal, the temperature, and the oxygen partial pressure. Inversion layers which form around the metal particles represent regions of n‐type conduction in the p‐type bulk. Beyond the percolati…
Negative temperature dependence (NTD) of electrical resistivity (ρ) was investigated on several Ti-Nb alloys quenched from 1073 K in relation to α″ martensite and athermal ω phases.The estimation of starting and ending temperatures of the athermal ω formation, ωs and ωf, respectively, was attempted with special care t…
Creep tests were conducted on Ni-base heat-resistant alloys Hastelloy XR and XR-II, i. e. versions of Hastelloy X modified for nuclear applications, at 950°C using four types of helium environment with different impurity compositions, and mainly the effect of carburization was examined.For all the materials tested, th…
The wicking and swelling properties of pure disintegrants were investigated from plugs prepared under conditions similar to those used in encapsulation of powder mixtures into hard gelatin capsules. Pure AcDiSol exhibited the greatest wicking and swelling action followed by Primojel, Polyplasdone-XL 10 and corn starch…
An investigation of the effects of different weft–insertion–system parameters on yarn velocity is reported. Increasing the air–supply pressure, initial loop length, and running speed decreases the total insertion time and hence increases the average yarn velocity. To examine the effects of yarn characteristics on yarn…
L'hygroscopie d'un excipient peut affecter la stabilite de la formulation d'une forme solide. Plusieurs marques de cellulose microcristalline et microfine, sont utilisees pour la fabrication de comprimes a base d'acide acetyl salicylique; l'etude de la degradation de ces comprimes permet d'evaluer l'influence des exci…
The compressive strength of two kinds of titanium alloys was investigated in the wide temperature range from 78K to 723K and the strain rate range from 10-4/sec to 103/sec. It was found that the flow stress increased with the rise of strain rate and with the decrease of temperature, while it was completely independent…
A shell disease of Crassostrea cucullata Born. (rock oyster), caused by the fungus Ostracoblabe implexa Bornet et Flahault, is reported from Indian waters for the first time. The fungus causes small dark flecks on the inner surface of the valves. Decalcification of shells revealed that the fungal hyphae grew within th…
Cholesteric samples, with cylindrical concentric layers, and with a non-singular core, show a helical instability with the same helicity as that of the cholesteric, when subjected to a radial dilation. It consists in a helical undulation of the core, the core being a perfect double-twisted zone. This instability devel…
This paper describes a case in which nonstandard test configurations had to be used to assess fracture toughness, and an experimental, analytical program to support the validity of the results. Zirconium alloy pressure tubes (103 mm inside diameter, 5 mm thick) contain the primary coolant in CANDU™ reactors. Because i…
On peut utiliser un modele theorique pour estimer les valeurs de la taille de capillaire et du volume de pore, deux parametres structuraux importants utilisables pour la prevision de la vitesse ou de la capacite d'absorption
Eight cardenolide glycosides and one genin, including two new glucoside conjugates, have been isolated from adult monarch butterflies (Danaus plexippus L.) the larvae of which were reared on Asclepias fruticosa L. leaves. The glycosides calactin, calotropin (major components), calotoxin, and afroside were identified b…
Phase relations involving genthelvite are studied on the basis of physical-chemical principles and natural occurrences. Stability diagrams and exchange operators are considered as well as an extended system, natural associations, and solid state relations. It is noted that the extremely high chalcophilicity of Zn expl…