Materials Literature
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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…
Mise au point d'un appareillage et d'une methode pour la mesure de la sorptivite des ceramiques poreuses
Aluminium porphyrins, such as chloroaluminium porphyrin, catalyse a novel hydrogen transfer process in the reduction of aldehydes or ketones with alcohols, and the reactions eventually proceed with very high stereoselectivities.
Via computer simulation, we have studied the characteristics of the ‘‘top-hat’’ electrostatic analyzer, which has in principle a 360° field of view in the acceptance plane. Explicit details are given on how the simulation calculations were done. A finite-difference method employing a polar mesh was used for the comput…
La cellulose provenant du papier de qualité chromatographique et incorporant des quantités diverses de carbonates et/ou d'hydrates d'éléments alcalins ou alcalino-terreux, a été soumise à un vieillissement dans des environnements secs et humides, à des températures allant de 60°C à 105°C. Les valeurs du pH extractif,…
Using coupled-mode theory, the coupling coefficient was calculated for a trapezoid grating, and it was shown that it is possible to adjust its shape to obtain a high coupling coefficient. This is one of the advantages offered by the ion beam etching technique.>
The optical antipodes of N-methyletioporphyrin I were resolved and characterized as the zinc complex with a chiral axial ligand by n.m.r. spectroscopy.
Hydrogen treatment of optical fiber waveguides with pure silica cores and boron, fluorine codoped silica claddings was found to effectively reduce the y-ray induced loss increases in visible wavelength region. Germanium-doped core fibers free from metal impurities had good resistance against y-rays. The induced losses…