Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Abstract Group-theoretic methods arising from Pólya's theory of counting are used to enumerate close-packings and polytypes of ZnS, CdI 2 , and SiC having layer-number N ≤ 50. The close-packings are further classified by space group. The barium ferrites of the form M N Y S with N = 2,4,6,8, lO and S ≤ 20 are enumerate…
It had been shown previously that the heat-stable polypeptide of the ATP-dependent proteolytic system of reticulocytes, designated APF-1, forms covalent conjugates with protein substrates in an ATP-requiring process. We now describe an enzyme that carries out the activation by ATP of the polypeptide with pyrophosphate…
A broad review of the physics of point defects, i.e. electrically active and neutral impurities and impurity complexes is given. Basic material science which is crucial for understanding the physics is summarized in an introductory section. It is followed by the detailed description of the novel measurement techniques…
The corrosion rate of copper in laboratory tests is shown to be a sensitive function of relative humidity, sulfur dioxide, hydrogen sulfide, ozone, hydrogen chloride, and chlorine concentrations. Observed indoor corrosion rates obey log normal statistics over the field population of this study. Also, the observed indo…
Abstract The crystal structure of a natural tobermorite from Zeilberg, Maroldsweisach, Germany (average formula Ca 2.2 5 [Si 3 O 7.5 s(OH) 1.5 ].-1H 2 O), is solved using the data obtained from an automatic diffractometer. For the structure determination only the sharp main reflexions are considered. The crystal data…
A fluorescent reagent, N ‐(1‐pyrenyl)iodoacetamide, was conjugated to rabbit skeletal muscle actin at the site of the most reactive sulfhydryl group, and fluorescence characteristics (excitation and emission spectra, quantum yields, lifetimes) of the conjugate were investigated. Associated with polymerization of label…
Luminescence-excitation spectra of the GR defect have been recorded at high resolution for an irradiated natural semiconducting diamond. Luminescence produced in the GR1 region was monitored while the wavelength of the exciting radiation was scanned over the GR1 and GR2-8 absorption systems and part of the ultraviolet…
Pressure-induced high-temperature superconductivity is observed in semiconducting ${({\mathrm{Sn}}_{x}{\mathrm{Eu}}_{1\ensuremath{-}x})}_{y}{\mathrm{Mo}}_{6}{\mathrm{S}}_{8}$, where $0<~x<~0.1$ and $y=1.0 \mathrm{and} 1.2$, having a carrier concentration \ensuremath{\simeq}${10}^{19}$/${\mathrm{cm}}^{3}$ at 4.2…
Starting from an atomistic sterical hindrance potential, translational and orientational motion of the N${\mathrm{O}}_{2}$ group in the deformable lattice are described. The reorientations of the N${\mathrm{O}}_{2}$ group in the paraelectric phase occur essentially by rotations around the crystallographic $\stackrel{\…
Dispersing coarse grains of Al2O3 in a fine-grained matrix of the same material a bending strength of about 500 MPa and fracture toughness of 8 MPa m1/2 are realized on conventionally as-sintered specimens. The improved mechanical properties of the bidisperse structure can be explained by residual stress initiated mic…
Complex admittance measurements are performed on high-purity ceramics prepared by means of the alkoxide synthesis and on less pure ceramics obtained from the citrate synthesis. The results on ceramic materials with grain sizes ranging from 0.4 to 20 μm are compared with those from a single crystal. The activation enth…
As an extension of Table 7.1.5B of International Tables for X-ray Crystallography [(1967), Vol. II. Birmingham: Kynoch Press], the possible stacking variants up to ten layers are arranged according to the percentage of hexagonal stacking. A method is given which allows one to calculate the number of possible stacking…
On the basis of the available force fields for the S8 ring the vibrational Raman intensities of an α-S8 single crystal and of a randomly oriented polycrystalline sample are interpreted in the frame of the bond polarizability model. The whole set of Raman tensors of the S8-molecular ring and of the single crystal inclu…
The surface-enhanced Raman spectrum of CO adsorbed on colloidal silver particles of about 100 Å diameter is reported. The spectrum resembles that observed for CO adsorbed on vapor-deposited silver. Only three strong Raman lines appear, at 2113, 160, and 64 cm−1. These are assigned, respectively, to the CO stretching,…
The fluorescence spectrum of ${\mathrm{Eu}}^{3+}$ in monoclinic ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$ is analyzed at 300, 77, and 4.2 K. There are three distinct ${C}_{s}$ crystallographic sites for the rare earth in the monoclinic structure. Through selective excitation of the three $^{5}D_{0}$ levels with a dye lase…
A theory of lattice thermal conductivity is formulated in which phonons are divided into propagating and reservoir groups. At high temperatures, the groups are differentiated according to whether they occupy nondispersive modes below or dispersive modes above the U-process combination frequency threshold. Below this t…
Transparent heat mirrors of the antireflecting metal type with a dielectric/metal/dielectric structure are studied. It is found that dielectrics of lower refractive index give a higher cutoff wavelength, but the transition becomes more gradual. The angular behavior of these mirrors is also analyzed. The optimum mechan…
The wave number dependence of the diffusion coefficient measured by dynamic light scattering is predicted in the dilute limit through a relatively simple, but rigorous, equilibrium analysis of the diffusion process. For hard sphere interactions with ak≲0.2 the gradient diffusion coefficient should be detected, but for…
Photoluminescence spectra of undoped crystals of the layer semiconductor GaSe have been measured from 80 K up to room temperature. The direct and indirect excitonic emissions are clearly observed in the intrinsic part of the spectrum. Moreover, a detailed analysis of the luminescence intensity has been made as a funct…
A method is described to derive average atomic-displacement energies from damage-rate measurements on polycrystalline materials under electron irradiation. The results for several cubic metals are compared to data obtained from electron irradiations of single crystals and to effective displacement energies derived fro…