Materials Literature
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A transmission-line model for surface discharge and the analytical solution of the model have been presented previously. In this paper, an attempt is made to interpret the various properties of surface discharge with this model. The properties discussed are the discharge starting voltage vs the specific capacitance; t…
Abstract Sedimentologic zones that are differentiated by changes in lithology, mineralogy, chemical composition, and crystal morphology observable in scanning electron micrographs occur in Missouri high-alumina clay deposits. These properties and changes suggest that the high-alumina materials originated from Pennsylv…
We present a calculation of the dielectric function for a quasi-two-dimensional electron gas (Q2D) and compare our results with those obtained for two-dimensional (2D) and three-dimensional (3D) electron gases. We also compare our results to those obtained using the Thomas–Fermi approximation. We find that for a Q2D s…
Abstract Some of the dosimetric properties of a high sensitivity thermoluminescence dosemeter material, LiF(Mg,Cu,P), are described. This material, prepared at the Chinese Academy of Medical Sciences, has about 23 times higher sensitivity than that of LiF(Mg,Ti). It is stable and reusable without significant loss of s…
Abstract An interpretation is given of the broadened EPR spectra of Gd 3+ ions, which are frequently observed in polycrystalline ceramics and glasses. A reasonable simulation of the spectra is obtained, when these are regarded as a superposition of a large number of normal EPR powder spectra, each of which can be desc…
SUMMARY Progressive graphitization is measured from X‐ray patterns by the probability P for finding a carbon layer pair reaching the graphite order in the solid. TEM studies show that all carbons (whether graphitizing or not) contain small basic structural units less than 10 Å both in thickness and in diameter which a…
The ferroelastic phase transitions in ${\mathrm{Pb}}_{3}$${(\mathrm{P}{\mathrm{O}}_{4})}_{2}$ and ${\mathrm{Pb}}_{3}{({\mathrm{P}}_{1\ensuremath{-}x}{\mathrm{As}}_{x}{\mathrm{O}}_{4})}_{2}$ are accompanied by large excess specific heats in a wide temperature range above ${T}_{c}$ and critical crossover above and below…
Abstract Surface‐enhanced Raman spectra of some amino acids (Phe, Tyr, Trp, His, Leu and Ala) and cytotoxin I from Naja naja oxiana adsorbed by silver hydrosols have been obtained. The spectra are enhanced from 100 to 200 times. Addition of aqueous solutions of the amino acids to the hydrosol resulted in the appearanc…
Three topical fluoride agents deposited surface coatings of different morphology and thickness on intact human enamel surfaces. The agents studied were an acidic silane fluoride lacquer, a neutral NaF lacquer, and an APF gel. Each agent reacted with the enamel surface differently, producing its own distinctive etching…
The reflectivity spectra have been measured on single crystals of CaO, CaS, SrO, SrS, SrSe, BaO, BaS and BaSe in the syncrotron radiation region of 440 eV. In order to prevent surface deterioration effect, all measurements have been made at 77 K on the fresh (100) surfaces cleaved within a high vacuum. From a chemical…
For ceramic AgNb03 the occurrence of a ferroelectric phase was ascertained at temperatures less than about 75°C. In the vicinity of this temperature, the functions of dielectric permittivity ∊, loss tangent tan δ, spontaneous polarisation Ps, total pyroelectric coefficient pt and the piezoelectric coefficient d33 vers…
The cholesteric blue phases (BP I and BP II) can be modeled as cubic lattices of disclinations in a cholesteric matrix. In an earlier paper we presented results of free-energy calculations for three models with ${O}^{2}(P{4}_{2}32),{O}^{5}(I432)$, and ${O}^{8}(I{4}_{1}32)$ space-group symmetry. In the present paper ca…
A newly developed electro-acoustic transducer technique is applied to the measurement of electric field intensity at a dielectric/electrode interface. This report describes the principles of this new technique as applied to: the residual electric field intensity by a sheet charge and its location in PET film, to the a…
Abstract Heptamethyl cobyrinate perchlorate, [Cob(II)ester]ClO4, was prepared in a good yield from cyanocobalamin. This hydrophobic complex is structurally comparable to the base-off form of vitamin B12r. Thermodynamic parameters (ΔG, ΔH, and ΔS) for axial ligation of [Cob(II)ester]ClO4 with various amines in dichloro…
A solution is given of the field equations of nonlocal elasticity for a line crack interacting with a screw dislocation in an elastic plane under antiplane shear loading. Displacement and stress fields are determined throughout the core region and beyond. In the case when the dislocation is absent, the circumferential…
Helium bubble nucleation has been studied at grain boundaries in a ternary austenitic steel after helium implantation in the temperature range 450–600°C. Transmission electron microscopy shows that all interfaces except the coherent twin are preferred nucleation sites for bubbles, and that the density of bubbles is gr…
Measurements are reported of the temperature dependence of the proton spin-lattice and spin-spin relaxation times ${T}_{1}$ and ${T}_{2}$ in yttrium and lanthanum dihydrides containing controlled levels of gadolinium as low as 50 ppm. The results demonstrate unambiguously that paramagnetic ions in concentrations so lo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnthracene pillared cofacial diporphyrinC. K. Chang and Ismail AbdalmuhdiCite this: J. Org. Chem. 1983, 48, 26, 5388–5390Publication Date (Print):December 1, 1983Publication History Published online1 May 2002Published inissue 1 December 1983https://pubs.acs.org/doi/10.1021/j…
A biotite that has substantially altered to chlorite in a granitic rock from south-central Maine has been investigated with high-resolution and analytical transmission electron microscopy. The reaction takes place primarily by the replacement of TOT mica layers in the biotite by brucite-like layers (mechanism 2). This…
Magnesian calcites with compositions between 0 and 24 mole% MgCO 3 were synthesized at high temperatures and pressures in cold-seal pressure vessels and in a piston-cylinder apparatus. X-ray powder diffraction and atomic absorption analyses of these phases reveal a non-linear, but smooth, variation in volume and c/a w…