Materials Literature
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Thermal stability criteria capable of explaining Thoma's observations that bias-induced reversible switching transitions in inhomogeneous thin insulating and semiconducting films occur at a critical value of local power density are developed and analyzed. One model, based on a relation between the temperature and heat…
The aberration theory of diffraction gratings has been studied by means of geometric optics. No restrictions are imposed on the form of the grating surface, the pattern of the grooves in the grating surface, and the position of the object. Furthermore, the image plane is not limited to one normal to the principal ray.…
Abstract Stereoselective syntheses of the two optically active pheromones of ants, (+)-(E)-4,6-dimethyl-4-octen-3-one (manicone) and (+)-(E)-2,4-dimethyl-2-hexenoic acid, and of β-sinensal and (E)-β-farnesene are described in which allylic thiolcarbamates readily derived from allylic alcohols via the [3,3]sigmatropic…
Second order transitions are discussed for compounds of the heavy rare earths and yttrium with cobalt. The calculated Curie temperatures agree well with those observed and an analogy is established between the effect of rare earth additions and of pressure. First order transitions in critical fields and at critical te…
This paper describes an improved method of predicting the breakdown voltage and volt-time characteristic of wood-porcelain combinations. The model accounts for the different voltage waveshapes that stress each element of the combination. The integration method is used to evaluate the breakdown and the time to breakdow…
Experiments are described in which the orientation and curl of fibre segments in some random, parallel, and cross-laid fabrics were examined with a scanning electron microscope (SEM). A technique for the measurement of these parameters that consists in the enlargement of the SEM photomicrographs to obtain traces of fi…
Abstract Wax migrates from the bulk of a rubber article to its surface to form a physical barrier to ozone attack. The extent of migration depends upon the solubility/mobility characteristics of the specific wax under a given set of environmental conditions. Factors which influence migration include time and temperatu…
Abstract Raw materials selection and method of synthesis determine the type of branching in a commercial branched fatty acid. The type of branching plus the isomer distribution, the normal chain/branched chain ratio, the chain length distribution, and the purity of the acid determine the physical properties of commerc…
Abstract Smectites were found to be dominant in the clay fraction of five calcareous soils of different great soil groups from various areas of Turkey. Characterization by X‐ray, thermal, infrared, and chemical analyses of these smectites in a Terra Rossa, Vertisol, Rendzina, and Volcanic Ash profile showed that they…
Scanning electron microscopes are now being developed to investigate the spatial distribution of chemical elements in the top few atomic layers of solids. Instruments using the Auger process are discussed here, as well as some applications to metallurgy and microelectronics
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic and spectral properties of chloroaqua[2,6-diacetylpyridinebis(semicarbazone)]iron(II) and diaqua[2,6-diacetylpyridinebis(semicarbazone)]nickel(II): ligand fields and bonding in pentagonal-bipyramidal complexesMalcolm Gerloch and Irene Morgenstern-BadarauCite this: I…
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Abstract The behaviour of the infrared‐active lattice vibrations of GaS, GaSe, InSe are studied by measuring the room‐temperature reflectivity in the 100 to 500 cm −1 frequency range when the incident wave vector is inclined at an angle θ to the crystallographic Z ‐axis. The experiments are performed in polarized ligh…
The complete differential electron-energy-loss probability is calculated for scattering of a fast electron by a thin uniaxial crystal foil at oblique incidence. Retardation effects are considered in the present calculation. In the long-wavelength limit the local dielectric tensor ${\mathrm{lim}}_{q\ensuremath{\rightar…
We concentrate on the Hall effect in magnetic 3d-metals, which shows an anomalous component varying nonlinearly with applied field. Its origin is spin-orbit coupling, and its manifestations are described as characteristic electron scattering processes: skew scattering and side-jump displacement. We shall consider thes…
Inelastic neutron scattering experiments in tetragonal KNb${\mathrm{O}}_{3}$ show a high anisotropy in some regions of the phonon dispersion relation and the existence of strong one-dimensional intercell correlations between atomic motions along the [100] and [010] directions, in agreement with x-ray diffuse-scatterin…
Superplastic behaviour in hot rolled AI-Si eutectic was investigated, for a grain size of 18 μm, over a range of strain rates, temperatures, and compositions. The AI-Si eutectic was successful in producing superplasticity with over 300% elongation. Two dominant superplasticity mechanisms seem to operate: a dislocation…
Abstract The clay mineralogy of soils from the moist southern Guinea savanna and subhumid northern Guinea savanna has been studied. All the soils occur on basement complex. Kaolinite is the dominant clay mineral in all the well‐drained soils, a property shared with the well‐drained soils of the humid tropical forests.…
The resistivity of CoS 2 having the pyrite structure was measured between 4.2 K and 300 K under pressure up to 18 kbar and under magnetic field up to 45 kOe. The hump anomaly just below the Curie temperature ( T c ) was found to become sharper with decreasing T c by pressure and to become sluggish with increasing T c…
Abstract Single filaments of nylon‐6 and of its mixtures with KCl, LiCl, and LiBr (salt content up to 5% w/w) were prepared by extrusion at 265°C. As‐spun filaments with a varying degree of orientation were obtained by altering the take‐up velocity a t constant outflow velocity. These as‐spun filaments were further su…