Materials Literature
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In a previous paper [Levitt, M., and Greer, J. (1977), J. Mol. Biol. 114, 181--239], an objective compilation of the secondary-structure regions in more than 50 different globular proteins was produced automatically. In the present paper, these assignments of secondary structure are analyzed to give the frequency of o…
A review is given of the present state of the theory of dynamic nuclear polarization (DNP) by the dipole electron-nucleus interaction in solids. The two-particle (solid effect), three-particle (electron-nucleus cross relaxation), and many-particle (dynamic cooling) mechanisms of DNP are discussed both for idealized co…
The EPR and optical absorption spectra of X-ray irradiated single crystal of Na beta -alumina have been examined. The most prominent absorptions are tentatively ascribed to an F + centre at the O(5) oxygen ion site in the conduction plane. To this defect the authors assign an axially symmetric EPR spectrum which shows…
Studies were carried out all the effects oj chemical com/Jositioll, mallu-Jacturing condition and heat-treatment oj lo w-carboll rimmed hot-rolled steel sheets on its susceptibility to stress corrosion cracking in 60C reagent methanol containing O.Olwt % Jormic acid and O.l wt O o water by using a constant strain-rate…
The nonlinear formalism developed by Zwanzig and Mori is utilized to derive a kinetic equation for the distribution of monomer phase space coordinates and a coarse-grained momentum density. Several simplifying approximations are then introduced into the exact kinetic equation. The resulting approximate description is…
An edge effect observed in high-resolution scanning Auger-electron microscopy is modeled by Monte Carlo methods based on the direct simulation of individual inelastic scattering processes. The Monte Carlo method permits the simulation of the spatial distribution of excited electrons generated by inelastic scattering.…
The response of an fcc crystal to unconstrained [110] uniaxial loading has been studied theoretically. Numerical calculations were made of load, stress (${\ensuremath{\sigma}}_{110}$), lattice parameters, and elastic moduli (${C}_{\mathrm{rs}}$) along the primary loading path, and the domain of $M$ stability (as defin…
Compared are recent EPR, susceptibility, and neutron measurements of both $S$-state (${b}_{4}^{0}$) and non-$S$-state (${A}_{4}^{0}〈{r}^{4}〉$) lanthanide-ion crystal-field splittings in metals. The ratio of the $S$-state to the non-$S$-state fields $\mathcal{R}=\frac{{b}_{4}^{0}}{{A}_{4}^{0}〈{r}^{4}〉}$ in some metals…
The infrared spectrum of the semimetal Ti${\mathrm{Se}}_{2}$ has been recorded over a broad range of energies, above and below its distortion temperature ${T}_{d}=202\ifmmode^\circ\else\textdegree\fi{}$K, a distortion for which electron-hole coupling is the likely source. Interpretation of the spectrum is immediately…
Inelastic-neutron-scattering techniques have been used to study the temperature dependence of the normal vibrational modes of hcp Zr. The phonon spectra along the [001], [100], and [110] symmetry directions were determined at 295, 773, and 1007 K. The [001] LO branch and a selected number of phonons of other branches…
The electronic energy bands of silicon dioxide in the $\ensuremath{\alpha}$-quartz structure have been calculated at several p\^oints of high symmetry in the Brillouin zone by the mixed-basis method. A tight-binding interpolation scheme has been used to determine complete valence bands and their state densities. The r…
Nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) techniques have been applied to study the phenomenon of methyl group tunnelling of various picolines and lutidines in the crystalline state over a wide range of temperatures. In most of these materials, two maxima—one is field independent—and two…
The exponential absorption edge (known as Urbach's rule) observed in most materials is interpreted in terms of thermal fluctuations in the band-gap energy. The main contribution to the temperature shift of the band-gap energy is due to the temperature-dependent self-energies of the electrons and holes interacting with…
For pt.II see ibid., vol.11, no.17, p.3591 (1978). The authors discussed the nature of the excitation spectrum of a structurally incommensurate phase, both when the displacement field is describable by a single Fourier component and when it may be described in terms of an array of phase solitons. In each case they est…
For pt.I see ibid., vol.11, no.17, p.3578 (1978). The authors studied the behaviour of systems undergoing structural transformations between commensurate and incommensurate ordered phases. They reviewed the theory developed by McMillan, and by Bak and Emery (1976) in which the order parameter for such phase transition…
We calculate the charge distribution $\ensuremath{\rho}(z)$ and Fermi-level distribution among the different graphite layers in a lamellar graphite acceptor compound. The charge distribution is highly nonhomogeneous and, because of the semimetallic nature of graphite, nonlinear effects are important. The calculations…
Coefficients have been determined for Berger's two-parameter formula for the Eisenhauer-Simmons gamma-ray buildup factors in ordinary concrete.
A detailed investigation was made, using Kerr effect cinematography, of the domain wall motion during cyclic magnetization in single crystals of a 3% Si-Fe alloy. At low levels of peak magnetic induction and magnetization frequency the midpoint of each slab-like domain remains stationary. With the onset of domain nucl…
There is an increasing demand both for thermoplastic and thermoset resins which, depending on the application, must exhibit one or more high performance characteristics. The resin chosen for a particular application must not only meet the end requirements but also must have good processing characteristics. High perfor…
Rotational hysteresis has been studied at very low rotational speeds in nearly isotropic polycrystalline materials. Measurements were made on disc shaped samples of pure iron, 1.2% C steel and mild steel. The magnitude and direction of the moment were measured as the disc was rotated starting from an initial magnetiza…