Materials Literature
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Hall-effect and electrical-conductivity measurements have been made on reduced single crystals of the perovskite potassium tantalate (KTa${\mathrm{O}}_{3}$) over the temperature range 1.6-295\ifmmode^\circ\else\textdegree\fi{}K. Lattice scattering predominates above 100\ifmmode^\circ\else\textdegree\fi{}K where the Ha…
The Curie point, lattice constants, sublattice magnetization, spontaneous magnetic moment, susceptibility, and the nonlinear susceptibility have been measured on the compounds RFeO3 with R yttrium or a rare earth. The main conclusions from these measurements are: (1) The rare-earth ions contribution to the magnetic pr…
This analysis provides the first precise crystal and molecular structural parameters for α-D-glucose. The C—C, C—H, and O—H bond lengths deviate only slightly from their means of 1.523 Å, 1.098 Å, and 0.968 Å. The C(1)—O(1) bond length, 1.389 Å, is significantly shorter than the mean value, 1.420 Å, of the other C—O b…
The silicones are in most cases relatively complex mixtures rather than pure molecular species. Their structures and chemical properties can be controlled, however, with sufficient reproducibility to give compositions with unique characteristics. The organic groups serve not only as a device for controlling the siloxa…
The mobility of substitutional boron in single crystals of graphite has been measured by an etch-decoration method, which makes it possible to locate individual boron atoms by electron microscopy. The mobility of boron is not very sensitive to the boron concentration, for B/C values between 10−2 and 10−8. The diffusio…
The melting curves of S, Se, and Te have been determined to 45 kbar by differential thermal-conductivity analysis in a tetrahedral anvil apparatus. The data for sulfur show that the melting point increases approximately linearly from 114\ifmmode^\circ\else\textdegree\fi{}C at atmospheric pressure to about 700\ifmmode^…
Polarized infrared spectra of isotactic polypropylene (IPP),[Complex chemical formula]were measured in the region from 4000 to 80 cm−1. The normal vibrations of these three polymers were calculated for the infrared- and Raman-active A and E species, by the use of the GF-matrix method with the Urey—Bradley force field.…
We have measured the radiative efficiency (ratio of $R$-line photons to the total number of photons emitted) and absorption cross sections for the $R$ lines of dilute ruby, as a function of polarization and temperature between 20 and 373\ifmmode^\circ\else\textdegree\fi{}K. We have also measured the fluorescent lifeti…
Received 22 December 1964DOI:https://doi.org/10.1103/PhysRevLett.14.217©1965 American Physical Society
The pressure dependence of the alpha-beta transition temperature in Ag(2)Se was determined by observing the temperature at which the sharp change in resistivity occurs when Ag(2)Se is transformed from the low-temperature orthorhombic to the high temperature body-centered-cubic form. The transition temperature increase…
Graphite contains varying concentrations of screw dislocations whose Burgers vector parallels the c axis. Single crystals of natural graphite contain very few such dislocations; furthermore, their Burgers vector always exceeds 450 angstroms. Pyrolytic graphites annealed above 3000 degrees C contain abundant screw disl…
Abstract Measurements of thermal conductivities of a number of pyrolytic graphites are reported including values for annealed, hot pressed graphite (IFPA 57). Thermal conductivities of IFPA 57 in both basal plane and c-axis directions approach the values for ideal graphite at higher temperatures. A theoretical estim…
Abstract Aus kleinen Ringen aufgebaute Polycyclen sind seit einigen Jahren bekannt. Ihre auch theoretisch interessanten chemischen und physikalischen Eigenschaften werden erläutert und Darstellungsmethoden an einigen Beispielen gezeigt. Besonders besprochen werden die Kohlenstoff‐Gerüste wie sie das Tetraeder, das Dew…
The average potassium oxide content of 18 Paleozoic two-layer monoclinic illites is 8.75 percent. There is an excellent linear relation between the ratio of the intensities of the reflections at 10 angstroms and 5 angstroms (10 A/5 A) and the potassium oxide content. The frequency distribution curve of the 10 A/5 A in…
Optically active amino acids contain many highly efficient optical second-harmonic generators. When light from a ruby laser at 6943 A falls on the crystalline amino acids with sufficient intensity, the second harmonic of the light at 3471 A can be observed. Although the symmetry requirements for optical second-harmoni…
Abstract The oxidative degradation of poly(ethyl acrylate) was investigated by infrared spectrophotometric techniques, and the volatile degradation products were determined by vapor‐phase chromatographic analysis. During the course of degradation, no change in the spectrum of the polymer, indicating the formation of o…
It is well known that the insulating ability of fabrics, singly, or in layers of clothing, may be towered sub- stantially if the clothing becomes wet, for example, from rain penetration.According-Iy.all-weather garments
Dynamic mechanical measurements were made with a low frequency (similar 1 c/s) torsion pendulum at temperatures from -170 to 150°C, on thin polytetrafluoroethylene (PTFE) sheet irradiated in vacuum at 23°C with doses up to 5 megarads of gamma radiation. Marked radiation-induced increases in shear modulus and decreases…
Orotidine-5′-phosphate pyrophosphorylase was isolated from wheat embryos and purified 35-fold. The enzyme is inhibited by high concentrations of orotate. Cu ++ and Mn ++ ions can replace the Mg ++ ion requirement. The enzyme shows a primary and secondary optimum at pH 8.5 and 9.8. Dihydro-orotate:NAD dehydrogenase als…
Abstract It is possible to draw analogies between linear polymers and cyclic compounds. Stereochemical considerations developed in this connection led to the recognition of new aspects of importance for the systematic classification of both classes of compounds; for example, asymmetric structures can be predicted whic…