Materials Literature
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Abstract Optimum reaction conditions were evaluated for assay of serum ceruloplasmin by measurement of its p-phenylenediamine oxidase activity. The pH optima of p-phenylenediamine oxidase activities of human and rat ceruloplasmins were 5.45 and 5.2, respectively. The p-phenylenediamine oxidase activity of rat cerulopl…
A first-order metal-insulator transition with no change in long-range order occurs in the mixed oxides ${({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{2}{\mathrm{O}}_{3}$ with increasing $x (x\ensuremath{\approx}0.01 \mathrm{at} 1 \mathrm{atm}\mathrm{and} 298 ^{\ensuremath{\circ}}\mathrm{K})$ or decreasing pres…
Abstract Under appropriate conditions, both surface areas and cation exchange capacities of clay minerals can be measured by absorption of methylene blue from aqueous solutions. The method has been applied to two kaolinites, one illite, and one montmorillonite, all initially saturated with Na + ions. For Na-montmorill…
The experimental evidence concerning the density of states in amorphous semiconductors and the ranges of energy in which states are localized is reviewed; this includes d.c. and a.c. conductivity, drift mobility and optical absorption. There is evidence that for some chalcogenide semiconductors the model proposed by C…
Abstract Durch reduzierende Methylierung des Octaäthylporphinato‐zinks [ 6a ; (OÄP)Zn] entsteht α.γ‐Dimethyl‐α.γ‐dihydro‐octaäthylporphinato‐zink [ 8a ; (ODMH 2 )Zn]. In Eisessig wird 8a zu (ODMH 2 )H 2 9 entmetalliert, das in diesem Medium Cu 2⊕ ‐ und Ni 2⊕ ‐Ionen unter Bildung von (ODMH 2 )Cu 8b und sehr stabilem (O…
The authors report experimental results in support of probabilistic theory to show that spatial fluctuations of the oxide built-in charge are effectively responsible for surface potential fluctuations, which result in an apparent density of interface states increasing with the mean image charge.
Abstract The relations developed previously for the spinodal and the consolute state in quasi-binary polymer solutions (single solvent and polydisperse polymer) are extended so as to cover quasi-ternary systems containing in addition a second polydisperse polymer. The equations obtained also describe polymer compatibi…
Abstract Test specimens of polymethylm ethacrylate (PMMA) have been subjected to stress in the presence of methanol and the resulting craze growth behaviour has been investigated by means of the concepts of fracture mechanics. Sharp-notched tension specimens have been tested over a wide range of constant applied loads…
Factors limiting the accuracy of orientations determined by electron diffraction are considered quantitatively. It is shown that errors in the lattice parameter and the effects of tilting the specimen or lens aberrations are not in practice limiting factors. The accuracy is limited usually by the measurement of the di…
Measurements of γtb/γgb for Cu and Cu-Al alloys utilizing transmission electron microscopy and selected-area electron diffraction techniques, and measurements of γSF for Cu-Al alloys from observations of extended dislocation nodes have shown that both γtb/γgb and γgF decrease with increasing atomic percent Al. Values…
Fulvic acid is a water-soluble humic material with relatively low molecular weight that occurs widely in soils and waters. It can combine with lyophobic organic compounds such as alkanes, fatty acids, and dialkyl phthalates to form stable "complexes" that are soluble in water. Fulvic acid in an aquatic environment may…
An optical absorption band is produced at 113 nm (11.0 eV) in both pure and Mg-doped LiF by irradiation with x rays at room temperature. This band, which appears to be intrinsic like the $F$ band, is identified as the ${V}_{3}$ band. Its peak-wavelength position follows the same dependence on anion radius as has been…
Piezoreflectance has been measured in single crystals of bismuth with light polarized in the basal plane of the crystal for photon energies in the range 0.6 to 4.5 eV. The stress modulation of the optical reflectance was achieved by cementing a nearly circular disk of bismuth onto a lead-zirconate-titanate disk set in…
The anharmonicity correction to the zero-point energy change in the triatomic dihydride isotopic self-exchange equilibria, H2X+D2X=2HDX, is discussed. It is shown that the inclusion of the usually ignored term G0 in the expression for the anharmonic correction to the zero-point energy (G0 + 14Σxij) causes the anharmon…
The tunneling characteristics of In-SrTi${\mathrm{O}}_{3}$:Nb and In-KTa${\mathrm{O}}_{3}$:Ca Schottky barriers have been studied at different temperatures and for different concentrations of carriers. The plot of differential resistivity shows a distinct peak at forward biases which is attributed to the critical poin…
The electrical conductivity for a system of electrons described by the single-band Hubbard Hamiltonian is studied. An expression for the electrical conductivity that is applicable in the narrow-band regime, i.e., the bandwidth $\ensuremath{\Delta}$, much smaller than intra-atomic Coulomb repulsion $I$ is derived. It i…
We have calculated the temperature coefficient of the long-wavelength refractive index of several group-IV and III-V semiconductors, using the Penn model for the electronic contribution to the dielectric constant. The isotropic band gap of this model is identified with the band gap at the $X$ point of the Brillouin zo…
Optical absorption and fluorescence spectra of Ho3+ in LaF3 have been obtained between 2500 and 21 000 Å. From an analysis of the data, it was possible to assign 2J + 1 Stark components to the observed states below 26 000 cm−1. A least-squares fit of 22 assigned J levels, with the inclusion of configuration interactio…
Macroscopic thermal dilatation coefficients as well as those of the lattice have been precisely measured along principal crystallographic directions of magnesium single crystals in the temperature range between room temperature and 650\ifmmode^\circ\else\textdegree\fi{}C. The vacancy concentration was thus obtained as…
The crystallographic structure of hexagonal NiS has been determined at temperatures above and below the metal-semiconducting transition. The powder x-ray diffraction peak intensities were used to determine the atom positions in both phases. The symmetry of the unit cell is found to change from $\frac{P{6}_{3}}{mmc({D}…