Materials Literature
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Abstract Previous studies on selective degradation of polyethylene single crystals with fuming nitric acid have been extended, both by using acid of lower concentration which gave better control over the degradation, and by resorting to ozone as an oxidizing agent which among others enabled the degradation temperature…
The properties of a highly correlated electron gas are discussed in relation to the recent work of Brinkman and Rice and the concept of the spin polaron. Tentative extensions of the theory are proposed for an electron gas in a random field, and these are checked against the observed behaviour of doped semiconductors.…
The cross section for stimulated emission for the 1·06 μm transition of Nd 3+ in glass has been determined by both laser and fluorescence measurements. Results from both methods were found to agree for six glasses studied. The change of cross section determined by the fluorescence method was established for a systemat…
There has been a recent surge of interest in the subject of amorphous semiconductors, a field which only a few years ago was generally considered to be about as scientific as witchcraft or alchemy. The major reason for the change in attitude is not difficult to pinpoint: the turning point was the publication by Ovshin…
We have measured the $g$-factor anomaly of the free electron to an accuracy of \ifmmode\pm\else\textpm\fi{} 3 ppm (68% confidence level). The method (a refinement of that used by Wilkinson and Crane in 1963) is based on a direct observation of the difference between the spin precession and cyclotron frequencies of 100…
Abstract Irradiation in the electron microscope causes many changes in crystalline polymers, but the most easily measurable of these is the change in the diffraction pattern from single crystals. It has been found that the intensity of a {1010} reflection from a polyoxymethylene single erystal decays exponentially aft…
Images have been obtained from the surface scanning electron microscope (SEM) by collecting backscattered electrons that have suffered a small energy loss in the specimen. This method can be applied to smooth specimens when viewed at oblique incidence. The modulation depth in the electron channelling pattern can be as…
Equilibrium electrical conductivity of nonstoichiometric poly‐crystalline BaTiO 3 with varying Ba:Ti ratios was investigated at temperatures between 800° and 1200°C and P o 2 from 10 −22 to I atm. A transition from p ‐type to n ‐type conductivity was observed. Although the electrical conductivity of different specimen…
The problem of step motion during lateral growth in solid-solid phase transformations is considered. The present model is concerned with the case in which volume diffusion in the parent phase is the predominant contribution to the growth rate, and it is assumed that the steps do not interact appreciably. The relations…
The interaction of oxygen with a polycrystalline W filament has been studied in the temperature range 300–1200°K and for exposures between 10−7 and 1 torr·sec. Both sticking probabilities and desorption spectra have been measured. After low exposures (〈2×10−6 torr·sec) the adsorbate is all desorbed as O atoms with fir…
Membrane-enclosed fecal pellets of planktonic herbivores were sampled at several depths in the Baltic Sea (459 meters deep) and off Portugal (4000 meters deep) by means of a Simonsen multinet. Pellets contained mainly empty shells of planktonic diatoms and silicoflagellates. Two kinds of fecal pellets were found, thos…
Abstract The presence of small amounts of divinylacetylene in the monomer during the emulsion polymerization of chloroprene results in substantial increase of the molecular weight, gel formation, and in corresponding changes of physical and mechanical properties of vulcanizates. These changes appear at concentrations…
Abstract The influence of small amounts of 1‐chloro‐1,3‐butadiene on the kinetics of the emulsion polymerization of 2‐chloro‐1,3‐butadiene and on properties of the resulting polychloroprene has been studied. Some changes in the properties of the chloroprene polymers were observed at 1‐chloro‐1,3‐butadiene concentratio…
Magnetostriction constants of MnxFe3−xO4 at room temperature are reported and related to the cation distribution in these spinels. Octahedral Fe2+ ions give a positive contribution to λ111. The contribution to λ100 of octahedral Mn3+ ions is negative in this system and is not a linear function of the Mn3+ concentratio…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrogen peroxide formation upon oxidation of oxalic acid in presence and absence of oxygen and of manganese(II). I. Manganese(VII), cerium(IV), chromium(VI), and cobalt(III) as oxidantsI. M. Kolthoff, E. J. Meehan, and Masaru KimuraCite this: J. Phys. Chem. 1971, 75, 21, 33…
Abstract This study was an investigation of the effects of sesquioxide constituents on some mineralogical and physiochemical properties of a Panamanian latosol. Latosols are soils characterized by high concentrations of iron and aluminum oxides and a general absence of free silica and alkaline earths. X-ray diffractio…
Abstract The contribution to the residual electrical resistivity of high angle grain boundaries due to the scattering of conduction electrons by voids into the boundaries is calculated for Au, Cu, and Al. Two types of geometries are considered: array of cylindrical voids for symmetrical tilt boundaries and point voids…
Floquet's theorem, and the general qualitative features of the band structure, are described in the one-dimensional case. The discussion includes a little-known unstable state at band edges that is not a Floquet function. This “band edge state” can in certain cases play a role in a thin crystalline layer, analogous to…
Human coronavirus (HCoV) infection causes respiratory diseases with mild to severe outcomes. In the last 15 years, we have witnessed the emergence of two zoonotic, highly pathogenic HCoVs: severe acute respiratory syndrome coronavirus (SARS-CoV) and ...Read More
An 18Ni (280) maraging steel has been tested in 3.5% NaCl solution under various modes of loading. The most severe condition was plane strain loading of fatigue precracked samples. The severity of stress corrosion cracking (SCC) of unnotched samples decreased in the sequence: plane strain bending, tension, plane stres…