Materials Literature
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Abstract Under some conditions, continuous crystallization exhibits cyclic changes of the particle size even with constant input conditions. A linearized stability analysis has been performed to determine under what conditions this behavior can be expected. Numerical solutions of the actual nonlinear system equations…
This paper compares the syntheses and the thermal stabilities of twelve related conjugated, pseudoconjugated, and nonconjugated Schiff base polymers of the general formula in which Z represents The polymers were prepared (a) by the condensation of Z(NH2)2 and p-C6 H4(CHO)2 in (1) solution and (2) as melts, and (b) by…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpin equilibrium in tris(2-aminomethylpyridine)iron (II) halidesGordon A. Renovitch and Willie Arthur. BakerCite this: J. Am. Chem. Soc. 1967, 89, 24, 6377–6378Publication Date (Print):November 1, 1967Publication History Published online1 May 2002Published inissue 1 November…
The effect of dispersions of either cobalt or silica upon the dislocation distributions in deformed copper crystals has been investigated. The crystals were deformed in tension, and three-stage stress-strain curves, similar to those of single-phase copper, were obtained. However, the precipitates caused an increase in…
Abstract Effects of filler on mechanical properties of composites result from stress concentrations developed in the matrix and filler particles. Stress concentrations in filler particles relieve stress in the matrix which, under a given load, deforms less than it would in absence of filler. This accounts for high mod…
Changes are reported in total cellular organic carbon, nucleic acids, proteins, carbohydrates, lipids and chlorophylls during the course of silicon-starvation synchrony of Navicula pelliculosa. All constituents increased at the same rate, relative to cell number, for 30 hours of exponential growth during which silicon…
The distribution of cations in different coordinations in the spinel structure as a function of equilibrium temperature was quantitatively determined for several phases. The spinels were synthesized and/or reacted at various temperatures and pressures. The relative X‐ray intensities of various reflections of the quenc…
Glutaraldehyde was quantitated by chemical titration, osmometry and ultraviolet spectrophotometry. Pure glutaraldehyde exhibited an absorption maximum at 280 mµ and absorbance at this wavelength conformed to Beer's law. A second maximum at 235 mµ indicated the presence of "impurities" (probably of polymeric origin), a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the reaction of some pyrophoric metals with oxygenThomas M. Gorrie, Peter W. Kopf, and Sidney TobyCite this: J. Phys. Chem. 1967, 71, 12, 3842–3845Publication Date (Print):November 1, 1967Publication History Published online1 May 2002Published inissue 1 November…
The polarized absorption spectra of Mn2+ in (CH3)4NMnCl3 and [(CH3)4N]2MnCl4 have been studied at 298°, 77°, and 2°K. Marked optical anisotropy was observed in both complexes. Details of the spectra indicate that the surroundings of the hexacoordinated Mn2+ ion are trigonally distorted from octahedral symmetry. Unlike…
The transition of amorphous alumina to α‐alumina was studied by X‐ray diffraction, electron diffraction, DTA, TGA, and microscopic observation. The amorphous alumina was prepared by condensing vapor from evaporating molten alumina in vacuo onto the glass envelope of the vacuum chamber. The amorphous alumina was transf…
A consistent electronic theory of adhesion is developed relating to the contact of bodies of different nature. The strength (as well as energy) of adhesion is calculated for the contact of crystal bodies (semiconductors, metals) as well as for the contact of amorphous bodies whose surface is saturated by donor and acc…
The addition of ThO 2 to Y 2 O 3 inhibits grain growth during sintering and allows the sintering process to proceed to theoretical density by maintaining a high diffusion flux of vacancies from the pores to the grain boundaries. The inhibition of grain growth is accomplished by the segregation of ThO 2 solute at the g…
The fracture behavior of a polyurethane elastomer in a hydrostatic tensile field has been experimentally studied via the ``poker-chip test.'' Microscopic examination of the material revealed residual gaseous bubbles, which were taken as fracture nucleation points. A study of the cavity behavior up through fracture ini…
ESR studies of radiophotoluminescence (RPL) centers in silver-activated phosphate glass were performed after the glasses had been γ-irradiated at 77°K. It is shown that the silver ions act as traps for both electrons and positive holes. By the separate formation of electron-trapped silver centers and hole-trapped silv…
The purpose of the paper is to clarify the mechanism of excitation energy transfer between unlike trivalent rare-earth ions in inorganic solids. We have measured the manner in which the intensities of the luminescences of Tb3+ (5D4→7F5) and Eu3+ (5D0→7F2) are quenched and the decay rates are made faster by the coexist…
Abstract The hydration of different forms of magnesium oxide by water vapour was studied at room temperature using gravimetric, X‐ray and electron microscopic methods. It takes place in four steps; formation of a layer of chemi‐ and physisorbed water, transition of magnesium and hydroxide ions in the layer of physisor…
Abstract The crystal structures of Mn 5 O 8 and Cd 2 Mn 3 O 8 are determined from single crystal and high resolution X ‐ray powder data. Both structures have very similar monoclinic unit cells, space group C – C 2/m, and are isotypic: equation image Hence, the true formula of Mn 5 O 8 is Mn Mn O 8 . The crystal struct…
The enthalpy of transformation of a high-pressure form of titanium dioxide, which has the alpha lead dioxide structure, to the rutile modification was measured by the method of "transposed temperature-drop calorimetry." For the reaction, titanium dioxide (alpha lead dioxide form) transforming to rutile, the change in…
A non-linear analysis of cellular convection driven by surface tension in a semi-infinite liquid layer heated from below has been made. The purpose is to determine whether or not one can predict the emergence of the hexagonal flow pattern from the interaction of a certain large class of important disturbances. The pri…