Materials Literature
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Abstract The dynamic mechanical properties of polyester and polyether urethane block polymers have been investigated at four frequencies (3.5, 11, 35 and 110 Hz) in the temperature range of — 150 to 200°C. The existence of a two phase structure was demonstrated in these systems by the observation of two major transiti…
Electrostatic properties of the point-plane electrode configuration are reviewed in the hyperbolic approximation. Simple expressions for the field in the neighbourhood of the tip are derived under the assumption that space-charge distortion is absent. Current induced by a charge carrier moving along a field line is in…
This paper describes a procedure which optimizes the fitting of a `model' of a protein to an electron density map. The technique seeks to minimize ∫ (Qo−Qm)2dv where Qo is the observed electron density and Qm is a density associated with a model in terms of which the observed densities are interpreted. Qm consists of…
A review of molecular-beam epitaxy of GaAs and the observation of surface structures with high-energy electron diffraction in an ultrahigh-vacuum system is described. The utilization of these surface structures as growth conditions to produce n- and p-type layers when doped with Sn, Ge, and Mg, and the electrical and…
The physical properties of many of the rare-earth intermetallic compounds have been collected together. They are discussed in terms of the role that the magnetic exchange and crystal field interactions play in determining these properties. It is pointed out that in this vast number of materials there is an ideal chanc…
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A method for increasing the rate of convergence of general crystal lattice sums of the type \sum_{j \ne k} qjqkr−njk is described. The method is applicable for n > 3, or for n > 0 if \sum_{\rm cell} qj = 0. A numerical example is given for the London dispersion energy (n = 6) of the benzene crystal. The calculation ef…
A new technique is proposed for the mathematical process of reconstruction of a three-dimensional object from its transmission shadowgraphs; it uses convolutions with functions defined in the real space of the object, without using Fourier transforms. The object is rotated about an axis at right angles to the directio…
The Maier-Saupe model of the nematic phase with an orientational order parameter is extended to the smectic $A$ phase by introducing a new order parameter, the amplitude of a density wave in the direction of the nematic preferred axis. Self-consistent equations for the two order parameters are derived from an anisotro…
Photoelectrochemistry is a new branch of physical chemistry, with many applications in the study of boundary layer structure, the energetics of electrons in solutions, the mechanism of photoemission, and the kinetics of fast reactions in solutions initiated by solvated electrons. 110 references.
The thermoluminescence of X-ray irradiated KBr and KBr:Cu crystals has been studied in the temperature range 300-510 K. Four glow peaks with first order kinetics are observed at 359, 377, 392 and 409 K for a warming rate 40 K min -1 . The trap depths for the above peaks are respectively 0.86, 0.97, 1.00 and 1.05 eV. T…
The dislocation mobility in zinc single crystals was investigated by measuring the shear modulus changes at frequencies of ≈ 10 Hz over the temperature range from 100 to 300 °K. The activation parameters of dislocation motion in basal (0001) 〈11―20〉 and pyramidal {11―22} 〈1123〉 slip systems were determined. From the r…