Materials Literature
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A simple, closed-form expression is obtained for the ballistic demagnetizing factor of a uniformly magnetized cylinder. Detailed comparison is made between the present results and both the previously derived series expansion (in which the radial variation of magnetization is neglected), valid for p(=length/diameter) ≥…
The kinetics of wetting of both high-energy (aluminum, mica) and low-energy (FEP Teflon) surfaces by thermostated polyethylene and ethylene-vinyl acetate copolymer melts in air were followed by the rate of approach of the apparent contact angle θ to its final value θ∞ and the change of the radius of the base of the po…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochromism of Synthetic and Naturally Occurring 2H-Chromenes and 2H-PyransRalph S. Becker and J. MichlCite this: J. Am. Chem. Soc. 1966, 88, 24, 5931–5933Publication Date (Print):December 1, 1966Publication History Published online1 May 2002Published inissue 1 December 19…
Abstract The bell-shaped pH rate profile for the reaction of tetrahydrofolic acid with formaldehyde to form 5,10-methylene tetrahydrofolic acid has been shown to result from a change in rate-determining step with changing acidity. In alkaline solution, the rate-determining step is the acid-catalyzed dehydration of hyd…
Abstract A process for preparing metiallic cobalt particles of uniform size in the 10–1000 A. range is described. Dicobalt octacarbonyl is thermally decomposed in solutions of dispersant polymers to form stable colloids of discrete particles which are separated by polymer coatings. Variatin of polymer composition, mol…
120 substances with one or more liquid crystalline phases have been studied in 180 binary systems by the combined examination of the relations of miscibility and the observation of the textures by means of a micro heating stage. The examinations enable us to give two systems of liquid crystalline phases. The system ba…
In enriched sea-water cultures inoculated with a mixture of algae and other organisms, concentrations of GeO2 above 1.5 mg/l specifically suppressed the growth of diatoms. In experiments with 14 pure cultures of diatoms (10 species), 1 mg GeO2/l sufficed to reduce the growth rates significantly; 10 mg GeO2/l was even…
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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.
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Abstract A review with 79 references.
A variational approximation is obtained for the resistance (or total entropy production) of a circular orifice in a plane diaphragm at which the scattering is specular. It is found that the Ohm's law prediction must be multiplied by a correction factor of the order of unity and added to the `small orifice' Knudsen con…
Abstract The viscoelastic properties of some polyester‐urethanes are compared with the properties of other polymers. The behavior observed is anomalous in that these polyurethanes exhibit an unusually high value of modulus well above their T g , unaccounted for by either crosslinking or crystallinity. Various experime…
A new theory of work hardening in dispersion-hardened single crystals—by which we mean soft crystals containing hard non-deforming particles of a second phase—is described. It is based on the fact that, if the particles do not deform plastically, and the interface between particle and matrix does not fracture, then se…
Abstract A new, general synthetic route to poly‐ p ‐xylylene and substituted poly‐ p ‐xylylenes is described. The key intermediate in the new process is di‐ p ‐xylylene [(2,2) p ‐cyclophane]. It has been found that di‐ p ‐xylylene is quantitatively cleaved by vacuum vapor‐phase pyrolysis at 600°C. to two molecules of…
CONTENTS I. Introduction 817 II. Tautomerism of phenols 818 III. Tautomerism of nitrosophenols 823 IV. Tautomerism of azophenols 825 V. Equilibrium phenol–quinonoid transformations of p -substituted phenols 827
Abstract Endor measurements on a type 1b diamond with paramagnetic nitrogen centres were made at 4.2, 77 and 300 °K by means of a 35000 Mc/s spectrometer. The axially symmetric nitrogen hyperfine coupling and quadrupole coupling parameters at 4.2 °K are Aiso., = 92.228 ± 0.001, Aaniso. = 10.903 ± 0.002, P = – 3.974 ±…