Materials Literature
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The acoustic noise spectrum associated with the collapse of transient cavities produced by a stirring rod in water was measured in the frequency range 1–3500 kc. While the spectrum, in general, goes as f−2 above 1 kc, flat regions are found between 20 kc and 100 kc, and again above 500 kc to at least 3500 kc. If the f…
A method for measuring the Hall mobility in insulating photoconductors is described which avoids the space-charge difficulties present in previous measurements. Unconventional electrodes are used, and the method differs from the conventional one in several other ways. It is a transient method, and the electric field i…
A constriction (defined as a point at which the two partial dislocations are recombined) must be formed before an extended dislocation can climb. The energy required is found to be about 6 eV, but may be reduced in the presence of an applied stress. Constrictions are more easily formed in Cottrell-Lomer locked disloca…
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Microwaves propagated between two doubly-curved parallel conducting surfaces, in the geometrical optics approximation, follow rays obeying Fermat's principle. The optical distance in this case is determined both by the index of refraction of the material between the surfaces and by the curvature of the surfaces. The f…
A description is given of a comparison method for determining the values of the absorption coefficient k of a metal relative to previously determined values for Ag. In this method transmission interference filters are constructed which have mica as the dielectric and have reflecting layers of Ag and of the metal x bei…
A study was made of the factors controlling the distribution of magnesium in the calcareous skeletons of marine organisms. The mineralogy of the carbonate appears to be the most important influence, with large amounts of magnesium occurring in solid solution in the calcitic forms and generally lesser amounts in the ar…
In this investigation, the relation of susceptibility to the $a$ dimension of crystallites was studied over the range from turbostratic carbons with diameters of 50 angstroms, to graphitic crystals with diameters of at least several thousand angstroms. Two series of carbons, one Thermax carbon black in powder form, th…
The resistivity and Hall coefficient of pure, single-crystals tellurium and of six single-crystal tellurium-selenium alloys, ranging from 2.7 percent to 13.2 percent selenium by weight, were measured over the temperature range 90\ifmmode^\circ\else\textdegree\fi{}K to 550\ifmmode^\circ\else\textdegree\fi{}K, and a few…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStandard X-Ray Diffraction Powder Patterns.Ludo K. FrevelCite this: J. Am. Chem. Soc. 1954, 76, 7, 2031Publication Date (Print):April 1, 1954Publication History Published online1 May 2002Published inissue 1 April 1954https://pubs.acs.org/doi/10.1021/ja01636a108https://doi.or…
THAT certain ancient silver articles, including coins, have in the course of time become exceedingly brittle is fairly well known. Silver coins which have been struck must have been ductile at the time of manufacture and hence have become brittle as a result of some sort of ageing process. This form of embrittlement h…
Hideo Yamatera, Kazumi Nakatsu; The Crystal Structure of Cs3Fe2Cl9 and of Cs3Sb2Cl9, Bulletin of the Chemical Society of Japan, Volume 27, Issue 4, 1 April
The air-drag of textile threads of different materials (e.g., nylon, rayon, wool, and especially cotton) has been measured over a range of air speeds from 20—600 ft/sec and over a range of counts. The results, the conclusions drawn from them, and descriptions of the experimental techniques used, are given in this pape…
Abstract The degree of polymerization of a polyamide is determined by the equilibrium between carboxyl, amino, and amide groups, and water molecules. Equations are deduced for the relationship between the equilibrium constant k 1 , the number‐average chain length n and the partial pressure of water. Allowance is made…
The appearance, growth, and structure of a cotton fiber are described, and photomicrographs and electron micrographs are used to illustrate both gross and fine features of the cell wall morphology. Heretofore, microscopy of the fiber has been limited to the use of dispersion, swelling and staining methods, in plain an…
Abstract The interaction between cellulose and heavy water allows absorptions due to stretching of OH groups in crystalline and amorphous regions to be studied independently. Crystalline regions give several absorption bands in the 3600–3000 cm. −1 range and it is shown that all the bands are due to stretching of OH g…