Materials Literature
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Magnesium metal immersed in thionyl chloride solutions becomes covered by a passivating layer which has properties of solid electrolyte. The buildup and the electrochemical properties of this layer were studied. Tafel slopes measured on freshly immersed Mg electrodes depend linearly on the apparent thickness of the SE…
The current theoretical formulations of optical absorption by small metal particles are critically reviewed. Several inconsistencies of the usual dielectric-function calculations are noted, and an improved expression is proposed. The results indicate that optical spectra should have a bearing on the difficult question…
Abstract not Available.
Abstract Pairs of four thermoplastic resins, polystyrene, poly(methyl methacrylate), acetal homopolymer, and nylon‐12, were intensively melt‐blended in nine proportions from 0 to 100 percent. Capillary rheometry at 210°C was done on each blend; melt densities were also measured on most of them. The dependence of shear…
The structure of a bartonite crystal from Coyote Peak, Humboldt County, California, has been solved and refined in anisotropic mode to a conventional R = 0.068for 504 observed reflections. The tetragonal unit cell [space group 14/mmm, a = 10.424(1), c = 20.626(1)A] contains 2 formula units, which were found by site-oc…
A large enough DC or low frequency AC field couples to the permanent polarization P and unwinds the helical texture of a smectic C* liquid crystal.′ From the measurement of the unwinding critical field, one can deduce the value of P. We present here a general model to compute the unwinding critical field; this model t…
Radiofrequency (rf) cold plasmas of argon, nitrogen, and air were used to modify cotton fabrics and yarns. Changes in surface characteristics were detected by application of the techniques of electron emission spectroscopy for chemical analyses (ESCA), electron spin resonance, and chemiluminescence. Examples of polyme…
Abstract In Mg‐ and Ca‐doped α‐Al 2 O 3 crystals irradiated by X‐rays at 80 K new paramagnetic colour centres are observed having an absorption band at about 255 nm and an emission band at 310 nm. The hyperfine structure of the EPR spectrum indicates that the unpaired electron spin interacts mainly with two Al 27 nucl…
The annealing of the electrical resistivity of two high-purity austenitic Fe-Cr-Ni alloys, and of Si- and Ti-doped samples has been investigated after neutron irradiation at 23K. The resistivity variations (a decrease below 190K, an increase between 190 and 600K, and a decrease above 600K) can be understood in terms o…
Secondary Langmuir-wave decay into another Langmuir wave and an ion-acoustic wave is shown to provide a very efficient saturation mechanism for two-plasmon decay and stimulated Raman scattering. Near the quarter critical density, where two-plasmon decay dominates Raman scattering, large ion fluctuations are expected a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of axial anionic ligand and porphyrin substituent effects on the oxidation of iron(III) porphyrins: porphyrin-centered vs. metal-centered oxidationMartin A. Phillippi, Eric T. Shimomura, and Harold M. GoffCite this: Inorg. Chem. 1981, 20, 4, 1322–1325Publicatio…
The polarization reversal of some tetragonal-phase PLZT ceramics is studied. The results are explained in terms of 90° domain wall motions. A reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase PLZT ceramics also by introducing the remanent degr…
Abstract K-bentonites of the Middle Ordovician High Bridge Group along the Cincinnati arch are characterized by interstratified illite/smectite (I/S) clays with rectorite-type ordering. Approximately 20% of the layers are expandable. They are structurally similar to I/S formed at temperatures exceeding 100°C during bu…
Tb3+ and Eu3+ bound to troponin C were detected by (1) changes in the fluorescence of the tyrosine chromophore of the protein or (2) the luminescence of the ions themselves excited by energy transfer from the protein or by direct excitation using a pulsed laser light source [Horrocks, W. DeW., Jr., & Sudnick, D. R. (1…
Nonevaporable getters have been widely used for many years in sealed vacuum or controlled atmosphere devices. They are also finding applications in other fields, where specific characteristics are required and tailor-made getters are requested, in some cases sacrificing speed in favor of lower activation temperatures,…
A computer simulation has been carried out for the core structure of a 1/3⟨1123⟩ {1122) edge dislocation using the truncated Lennard-Jones (12–6) potential. The core is composed of two distinct structural units which can be interpreted in terms of {1121) and {1122) twins. This core structure differs markedly from that…
The temperature factor (B = 0.70 Å2) and atomic parameter (x = 0.305) were determined by comparing the observed and calculated powder diffraction data for synthetic β-PbO2. This material is tetragonal with a = 4.961 (2), c = 3.385 (2) Å, and space group P4/mnm.
The effect of oxygen adatom coverage and order upon the formation of CO3 intermediates via CO2+O(a)→CO3(a) was examined on the Ag(110) surface. The reaction probability for CO2 was found to be strongly dependent upon the oxygen adlayer. Adsorption of CO2 upon an ordered oxygen adlayer at 300 K occurred with a net reac…
The orientation of some fluid (DF) and optically uniaxial columnar (D) discophases by surfaces is examined by optical microscopy. The test materials are 2,3,6,7,10,11 hexa-substituted triphenylenes, including two new compounds exhibiting mesophases at room temperature, and a binary mixture with a DF, phase stable betw…
We have measured the twist viscosity Y′(T) by the rotating field method, over the entire nematic range of the 4,4′-di-n-alkoxyazoxybenznes (mOAB) from m = 2 to m = 7. The results of these measurements are presented here together with a new development of our previous theory of γ1(T) which accounts for the free volume…