Materials Literature
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Data necessary to determine the activation energy and volume of the creep process in zinc have been obtained in the temperature range 1.5 to 80 °K by means of a differential technique. While calculating the activation parameters the influence of quantum phenomena on fluctuation-induced dislocation motion over local ba…
The authors have discussed earlier the photomagnetoelectric effect in graded-band-gap semiconductors assuming symmetrical band-edge gradients. The present paper rewrites the continuity equation under asymmetric band-edge gradients, and includes the effects of position-dependent minority carrier lifetime, electron and…
The heat and entropy of the transformation ice III–IX has been measured by a differential calorimetric technique as −0.32 cal K−1 mol, compared with the value −0.805 cal K−1 mol expected if ice III were fully disordered and ice IX were fully ordered within the limitations of the ice rules. It seems likely that there i…
Contrary to recent claims, no correlation of useful predicting power exists between the tendency of a nematic liquid to align transverse to a solid surface and the difference between the surface free energies of the nematic liquid and of the substrate. Observations that lead to this conclusion are reported for systems…
The ion-pair interaction potentials obtained by using the modle presented in our previous paper are applied to some ionic crystals. The calculated lattice properties of alkali-halide and alkaline-earth-dihalide crystals agree quite well with experimental data. The polymorphic transitions of alkali-halide crystals at h…
We determine bandwidths and critical-point positions with respect to the valence-band edge for the valence bands of several extensively studied semiconductors (with an accuracy of about 0.3 eV) by using photoemission densities of states derived from photoemission spectra obtained in the 24-78-eV photon energy range. T…
Electronic transport has been investigated in ${\mathrm{As}}_{2}$(${\mathrm{Se}}_{1/3}$ ${\mathrm{Te}}_{2/3}$${)}_{3}$ and Ge(${\mathrm{Se}}_{1/3}$${\mathrm{Te}}_{2/3}$ ${)}_{2}$ amorphous semiconductors through measurements of photoconductivity, optical absorption, dark conductivity, thermoelectric power, and field e…
Mutant adenylosuccinate lyases of Bacillus subtilis were prepared by site-directed mutagenesis with replacements for His141, previously identified by affinity labeling as being in the active site [Lee, T. T., Worby, C., Dixon, J. E., and Colman, R. F. (1997) J. Biol. Chem. 272, 458-465]. Four substitutions (A, L, E, Q…
The spectra of corona discharges in air at atmospheric pressure, in a 0·6 m point-plane gap under positive impulse voltage, have been measured in the near-ultraviolet and visible regions. Two types of corona discharges have been investigated: the first corona which develops from the electrode tip; and the leader coron…
A technique is presented which enables the recovery of the probability distribution for single scattering from plural-scattering electron energy loss data. Neither the scattering parameter t/λ nor details of the component processes need be known. The computational method uses Fourier series in order to overcome a numb…
Luminescence at 368 nm from crystals containing ${\mathrm{Eu}}^{2+}$ exhibits the small spectral shifts from host to host typical of a parity-forbidden rare-earth transition, and yet has the emission oscillator strength ($f\ensuremath{\gtrsim}1$) of a highly allowed transition. It is improbable that this anomaly can b…
In the layer structure MoS 2 , the oscillatory inter-band magneto-optic absorption has revealed a mass ratio of the order of 0.01. Theory is presented to show that this mass may be associated with the H-point of the Brillouin zone. Moreover, it is proposed that the origin of the mass is an instability of the equally-s…
Comparative powder Raman studies on zircon (ZrSiO 4 ) and hafnon (HfSiO 4 ) are reported. It is shown that rotational and translational modes of the same symmetry can be identified by comparing the spectra of these two crystals in a similar way as could be done by means of isotopic substitution. The authors also show…
We report a method for operating twisted nematic devices with rapid turnoff times by using a nematic material with variable dielectric anisotropy. These are useful as fast shutters and colour switches, and can be operated at a 25 Hz repetition rate.
Abstract The crosslink density of small microtomed samples of rubber vulcanizates has been determined using a gas‐chromatographic method for estimating the amount of solvent in the swollen rubber. The method may be used for determining the variation in crosslink density through thick rubber articles, for determining t…
Menachem Rahat, Richard D. Campbell, Three Forms of the Tentacled and Non-Tentacled Fresh-Water Coelenterate Polyp Genera Craspedacusta and Calpasoma, Transactions of the American Microscopical Society, Vol. 93, No. 2 (Apr., 1974), pp. 235-241
Through extensive testing in fission-reactor programs, molten Li2BeF4 is known to be compatible with graphite and with many useful structural metals. In service as a Controlled Thermonuclear Reactor blanket-coolant fluid, however, corrosion by this molten salt may be enhanced by (a) the effect of magnetically induced…
Effect of pressure on the CuAu alloy having a long period ordered structure has been studied using mainly a tetrahedral-anvil type press. The alloy was annealed at various temperatures ranging from 350°C to 500°C during application of pressure. After temperature and pressure were reduced to ambient ones, the structure…
Single crystals of Pb3GeO5 were grown from the melt by the Czochralski technique. Based on observations of the domain structure under mechanical stress, and the presence of an SHG signal, the crystals are ferroelastic and possibly ferroelectric, but show no phase transitions up to the melting point (738°C). The powder…
Thermal stabilities of mature insoluble collagen, salt-precipitated fibrils of acid-soluble collagen and acid-soluble collagen in solution were compared as a function of acid pH. Both insoluble and precipitated collagens showed large parallel destabilization with decrease in pH, whereas the intrinsic stability of indi…