Materials Literature
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Exposure of single crystals of Mg${\mathrm{Al}}_{2}$${\mathrm{O}}_{4}$ to fast neutrons and to Van de Graaff electrons with energies in excess of 0.35 MeV introduces an optical-absorption band at 5.3 eV with a 1-eV half-width. This band can be partially bleached at temperatures as low as 40 K and a shoulder at 4.75 eV…
X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) have been used in a study of the electronic structure of iodine-doped polyacetylene. Core level and valence band spectra are used to assess the nature and the consequences fo the iodine doping. The spectra are compared with our previous results on pure and…
Solitons in a one-dimensional charge-density-wave system with half-filled electron bands are studied theoretically with a continuum model. This model is a continuum version of the one of polyacetylene recently considered by Su, Schrieffer, and Heeger (SSH). We have analyzed a variational solution with the displacement…
Abstract The electronic ground state of Tm3+, 3H6, is a non-Kramers doublet which, below a critical temperature TD, is split by a cooperative Jahn-Teller distortion. Radiofrequency measurements of the susceptibility have established that (a) TD = 2.156(5) K; (b) most of the magnetic specific heat above TD comes from r…
The photoemission of Cr films deposited under UHV conditions has been investigated in the photon energy range from 30 eV to 230 eV. The 3p-3d intershell interaction gives rise to a strong maximum in the 3d partial yield above the 3p threshold.
The electronic structure and vibrations of an adsorbed hydroxyl (OH) species are identified and characterized for the first time on a transition-metal surface. In this study of water's interaction with clean Pt(111) in ultrahigh vacuum, water adsorbed at 100 K desorbs at 180 K without appreciable dissociation. However…
Abstract The photoredox behaviour of two water soluble derivatives of zincporphyrin, 5,10,15,20‐tetra‐ p ‐sulfonatophenyl ( 1 ) and 5,10,15,20‐tetra‐p‐ N ‐methylpyridiniochloride ( 2 ), was investigated using laser and continuous photolysis techniques. Photoexcitation produces triplet states whose lifetimes in aqueous…
The PACER LIME testing program employed two methodologies for classifying airbase environments: An a priori computation of a numerical corrosion factor which represents a composite of commonly-measured weather and geographical factors. This corrosion factor was not presumed to measure the actual environment corrosivit…
The use of dissimilar metals in heat exchanger designs is a common practice. In many instances, these combinations perform to expectations and few difficulties are encountered. At times, the combinations of materials selected, or the environments to which they are exposed, result in serious galvanic corrosion problems…
Eight species of freshwater plankton algae were fed to three species of duck. No viable cells of any of the algal species were found in faeces from Australian white-eye or tufted duck. Growth of the diatom Asterionella formosa was found in two cultures inoculated from the faeces of mallard and the significance of this…
With use of the characteristic turning-point radii of the first-principles nonlocal density-functional atomic pseudopotentials, a successful topological prediction of the crystal structures of 495 binary $\mathrm{AB}$ compounds of transition and simple elements is obtained.
Abstract A numerical method for calculation of the weight‐fraction distribution resulting from random crosslinking of polydisperse primary chains is suggested. The method is based on the numerical inverse Laplace transform of the weight‐fraction generating function given by the theory of branching processes. The appli…
Summary Two different parageneses for cebollite, a rare hydrated calcium aluminium silicate, are described, both differing from all previously reported occurrences. Cebollite forms concomitantly with natrolite from plagioclase in xenoliths of crustal material incorporated in kimberlite. The mineral also occurs as a la…
Abstract The magnetic susceptibilities for seven binary alloy systems (SnTe, SnSe, InTe, InSe, AgTe, AgSe and AgS) are measured as a funtion of temperature and composition. The diamagnetic susceptibilities of these systems fall rapidly on melting except for the InSe system, and decrease gradually with increasi…
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Abstract Flow crystallization experiments which utilized the Instron rheometer in conjunction with convergent dies were conducted for the purpose of producing high‐modulus poly(ethylene terephthalate) filaments directly from the melt. A temperature gradient was imposed on the lower extremity of the dies in an attempt…
A new explosive loading technique is applied to study the uniform plastic expansion and fracture initiation of 304 stainless steel cylinders. An annular layer of dry PETN high explosive is placed in contact with the inner diameter of the cylinder and surface-initiated with an array of etched copper bridgewires. This t…
Summary Both new species are retrograde or mesogene minerals that occur in tactites at the Christmas mine, Gila County, Arizona (USA). Gilalite is green, H = 2, D = 2.82. Biaxial (—), 2V small, α = 1.560, β = γ = 1.635. No single crystals found; strongest lines at 13.49 Å, (10); 10.97 (5); 7.786 (5). Analysis gave CuO…
Abstract When cellulose is phosphorylated with phosphorus oxychloride, the reactivity of the cellulose, as well as reaction time and temperature, influences the relative amounts of phosphorylated and chlorinated product formed. The swelling ability of the phosphorylated product is affected by the pretreatment received…
Abstract A wide compositional range of copolymers of 1‐cyclobutene carbonitrile (CBCN) and 1‐bicyclobutance carbonitrile (BBCN) with common vinyl monomers was prepared in order to study systematically the effect of cyclobutane carbonitrile ring incorporation on the glass transition temperature ( T g ). In general, the…