Materials Literature
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The asymptotic value of the isothermal thermomagnetic figure of merit is obtained for a two-band multivalleyed semiconductor or semimetal where the concentration of holes and electrons is equal. The bismuth band structure is used as a specific model. It is shown that at strong magnetic fields the isothermal Nernst coe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Esterolytic Catalysis of Poly-4(5)-vinylimidazole and Poly-5(6)-vinylbenzimidazoleC. G. Overberger, T. St. Pierre, N. Vorchheimer, and S. YaroslavskyCite this: J. Am. Chem. Soc. 1963, 85, 21, 3513–3515Publication Date (Print):November 1, 1963Publication History Published…
KAZUTOSI NISIZAWA, TOSHIJIRO YAMAGUCHI, NOBUHIKO HANDA, MASAAKIRA MAEDA, HISASHI YAMAZAKI; Chemical Nature of a Uronic Acid-Containing Polysaccharide in th
SUMMARYThe development of Thraustochytrium roseum, a new pigmented marine Phycomycete, is described from its growth on pollen in sea water. Morphological variations produced on nutrient media under diverse conditions are detailed. When cultivated in shake culture, light accelerated the logarithmic growth phase of the…
Abstract Es wird ein Modellbild vom Mechanismus der Wärmeübertragung an siedende Flüssigkeiten entwickelt. Dazu wird zunächst die Bildung von Dampfblasen an festen Wänden studiert. Mit Hilfe der dabei gewonnenen Ergebnisse läßt sich der Einfluß der Blasenbildung auf den Wärmeübergang untersuchen. Damit ist es möglich,…
Abstract Powders and compacted preforms of virgin unmelted polytetrafluoroethylene were subjected to ionizing radiation in high vacuum. The specific gravities, melt Visccmities, and mechanical strengths of the irradiated samples after a standard heating cycle in air or at reduced pressures indicate that degradation is…
Work on the study of the ejection of electrons from the surface of polycrystalline tungsten by ${\mathrm{He}}^{+}$, ${\mathrm{H}}_{2}^{+}$, ${\mathrm{N}}_{2}^{+}$, and ${\mathrm{O}}_{2}^{+}$ is reported. The total yields and energy distributions of the Auger electrons ejected by ions of 50-, 100-, and 200-eV kinetic e…
A series of rare-earth phosphates, arsenates, vanadates, tantalates and niobates have been reacted at pressures up to 80,000 atm. and temperatures up to 600°C. The structures of the high-pressure phases “quenched” to ambient conditions have been evaluated by x-ray powder diffractometry. The majority of the arsenates (…
Cultures of normally proliferating Hela cells have been examined in thin sections by electron microscopy following glutaraldehyde fixation, staining in Wachstein and Meisel's adenosine triphosphate containing medium, postosmication, and embedding in an epoxy resin. The cells were stained in suspension in order to ensu…
The work hardening of nickel single crystals and its temperature dependence are investigated. The results are discussed in terms of the long-range stress theory of work hardening. From an analysis of the temperature dependence of the stress τIII at the onset of stage III, we deduce the stacking fault energy of nickel…
Abstract The oxidative thermal degradation of polyacrylonitrile has been examined using infrared spectroscopy. It was found that the generally accepted mechanism for the thermal degradation of polyacrylonitrile in air, which involves direct interaction of neighboring nitrile groups, and alternate proposals, involving…
Abstract When polymers are extruded from a reservoir through a capillary the extrudate diameter is generally greater than the capillary diameter. Experiments with polyethylene show that the extent of this extrudate swelling depends, at constant shear stress, on the length‐to‐radius ratio of the capillary even though t…
The work-hardening properties of niobium single crystals grown by electron-beam zone-melting have been investigated over a wide range of purities, orientations, temperatures and strain-rates. Three stages of hardening are observed after the onset of plastic flow. The initial flow stress decreases with increasing purit…
Abstract Resinous materials have long been used to aid in the processing of rubber and to impart special properties to the vulcanized product. Resins have been described as various solid or semisolid organic substances. Originally, naturally occurring resins such as rosin were employed but with the advent of synthetic…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptically Active Polyamides. Poly-D(-)-β-methyl-ϵ-caprolactamC. G. Overberger and H. JablonerCite this: J. Am. Chem. Soc. 1963, 85, 21, 3431–3435Publication Date (Print):November 1, 1963Publication History Published online1 May 2002Published inissue 1 November 1963https://do…
A semiempirical formula is developed which yields values for the differential dose albedo of gamma rays on concrete. Gamma rays of incident energies 0.2, 0.5, 1.0, 2.0, 4.0, 6.0, and 10.0 Mev are considered. Results of the semiempirical formula are compared with values derived from Monte Carlo calculations for the bac…
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
Abstract The crosslinking efficiencies of dicumyl peroxide in SBR, cis ‐polybutadiene, acrylonitrile–butadiene rubber, and polychloroprene have been measured. For the first two rubbers approximately ten crosslinks are formed per molecule of peroxide decomposed, while for the acrylonitrile–butadiene rubber an efficienc…
The glow peak emission due to impurities in calcite, dolomite, magnesite, aragonite, and anhydrite have been investigated by measuring and interpreting the associated spectra. The impurities considered are Mn++, Pb++, Zn++, and Sb3+.The emission spectra due to Mn++ are interpreted on the basis of crystal field theory…
Magnesium oxide prepared by calcining the carbonate at 1000°C was sintered at 1800°C and ground under methanol. Well‐sized 2 to 5 and 5 to 10 μ fractions were separated. After outgassing at 550°C in vacuum, the powders were hydrated at various temperatures to 98°C in a wide range of water vapor pressures, and the reac…