Materials Literature
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The optical density of a flame fusion single crystal plate of CaTiO3 is reported. The refractive indices for the visible region are given, with nD = 2.403±0.02. The results of dielectric constant and loss measurements over the temperature range from 90 to 430°K reveal no unusual behavior. A room-temperature dielectric…
The structure of KttSO 4 has been determined and refined in two projections. The two ttSO~-groups in the asymmetric unit are differently linked by hydrogen bridges: one set forms 'dimers' across a symmetry centre; the other is linked into infinite chains along a glide plane. All hydrogen bridges are approximately alon…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSeparation of Orthohydrogen from Parahydrogen and of Paradeuterium from Orthodeuterium by Preferential AdsorptionClarence M. Cunningham, Douglas S. Chapin, and Herrick L. JohnstonCite this: J. Am. Chem. Soc. 1958, 80, 10, 2382–2384Publication Date (Print):May 1, 1958Publicat…
A statistical theory of the excluded volume effect in a polymer molecule is developed, making use of a pearl necklace model with a continuous medium approximation. For the mean square end-to-end distance 〈R2〉 and the mean square radius of gyration 〈S2〉, the theory leads to the same expressions as Zimm, Stockmayer, and…
Specific Volume and Degree of Crystallinity of Semicrystalline Poly (chlorotrifluoroethylene), and Estimated Specific Volumes of
Occasionally an electron paramagnetic resonance absorption line is accompanied by satellite lines which result from a weak magnetic dipole-dipole interaction coupling the electron spin to a neighboring nuclear spin. The satellites correspond to a change in spin state of the neighbor nucleus concurrent with the change…
Abstract Berichtet wird von den Anfängen der Fluorchemie und der ersten Darstellung von Polytetrafluoräthylen und Polytrifluorchloräthylen. Die strategische Bedeutung und die Kombination von Eigenschaften lassen erkennen, daß besonders Polytetrafluoräthylen ein unentbehrliches Hilfsmittel in vielen Industriezweigen wi…
Abstract Corrosion tests have been carried out on lead totally immersed in solutions of organic acids (0·1–0·0001 N). The corrosion rates in acetic, propionic, butyric, succinic, and lactic acids of the same normality were very similar, while pyruvic acid appeared to form a protective film. Inter‐crystalline attack wa…
T he behavior of an infi nitely long flexib le fil a men t after transverse impact is treated theoret.icall y. The fil a ment is ass u med to have a tension-strain curve that is always co ncave dow nward, and to have no short-ti me creep or stress-rei fixation effects. Under most cond itions the impact in itiates a va…
During recent yea rs a co nsid erable nurnber of t heo retical a nd exp erimental stud ies have been published o n t he kin etics and mechanism of t he t hermal d eco mposition of poly mers. The tr eatment of depo. lymerization as a free-rad ical chain reaction involv ing t he four basic steps of initiation, p ropagat…
Abstract Melt viscosities of styrene homopolymers and copolymers with 1.5 to 23 mole‐% methacrylic acid were measured with a parallel plate plastometer. Apparent viscosities were found to drop off sharply with increasing rate of shear in the range 10 −4 to 10 −1 sec. −1 . An increasing concentration of carboxyl groups…
Abstract Silicon nitride has been prepared by heating pure silicon in purified nitrogen at 1450°. X ‐ray studies showed the presence of two nitrides, and a method was therefore devised to separate them. Although these nitrides differ in their crystal structure, they have the same compositions, corresponding to Si3N4.…
The crystal structure of the low-temperature form of sodium triphosphate, Na~P3010, Phase II, has been determined by Fourier methods. The unit cell is monoelinic with [a] -----16.00, [b] ----5-24, [c] --~ II.25 A, fl --93 . The space group is C2/c and the unit cell contains 4 units of NasP3010. The triphosphate ions h…
The twist due to a screw dislocation parallel to the axis of an isotropic cylinder of arbitrary cross section can be found from the solution of the ordinary torsion problem for the same cylinder. Some particular cases are worked out. The results are also valid for certain kinds of anisotropy.
The refractive index n and the absorption coefficient k of evaporated CeO2 films were measured in the wavelength region from 0.22 μ to 1.0 μ. Films produced by direct evaporation of CeO2 were found to be extremely durable and nonabsorbing in the visible and can be used as beam splitters and as high-index films in mult…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT1,3,5-Triaryl-2-pyrazolines for Use as Scintillation SolutesRICHARD H. WILEY, C. H. JARBOE, F. N. HAYES, E. HANSBURY, J. T. NIELSEN, P. X. CALLAHAN, and M. C. SELLARSCite this: J. Org. Chem. 1958, 23, 5, 732–738Publication Date (Print):May 1, 1958Publication History Publishe…
Transmission electron micrographs of aged aluminium 4%-copper foils have shown unusual contrast near precipitated particles. This is interpreted in terms of Bragg diffraction from regions distorted by elastic coherency strains between the precipitate and the matrix.
A body armor panel consisting of twelve identical layers of 2 X 2 basket weave nylon fabric was investigated after impact by a fragment simulator .22-caliber steel missile in the range of 330-420 m. sec. (1100-1400 ft. sec.) striking velocities. The kinetic energy of the projectile was either slightly higher or lower…
The antiferromagnetic structure of Mn${\mathrm{Br}}_{2}$ (${T}_{N}=2.16\ifmmode^\circ\else\textdegree\fi{}$K) has been determined by single-crystal neutron diffraction measurements at temperatures down to 1.35\ifmmode^\circ\else\textdegree\fi{}K and with magnetic fields (0-13 kilo-oersteds) applied to the sample. The…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Electrical Conductivity of Solutions of Alkali Metals in their Molten Halides1H. R. Bronstein and M. A. BredigCite this: J. Am. Chem. Soc. 1958, 80, 9, 2077–2081Publication Date (Print):May 1, 1958Publication History Published online1 May 2002Published inissue 1 May 1958…