Materials Literature
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When polymers are degraded by submitting them to shearing action, neither the probability of scission of a macromolecule, as a function of molecular weight (MW), nor the probability distribution of the lengths of the resulting fragments is known a priori. Information about these probabilities can be obtained by compar…
Abstract The thermal oxidative degradation of two aromatic and one segmented polyurethane has been studied, with special emphasis on HCN evolution over a range of temperatures and oxygen concentrations. A tentative mechanism for HCN formation has been presented. Other gaseous products were ascertained by chromatograph…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemical consequences of ionic bonding in alkali metal acetylacetonatesMorton Raban, Eric A. Noe, and Gaku YamamotoCite this: J. Am. Chem. Soc. 1977, 99, 20, 6527–6531Publication Date (Print):September 1, 1977Publication History Published online1 May 2002Published inis…
The stresses and strains generated in the outer pyrocarbon (PyC) coating of a two-layer Biso fuel particle coating during irradiation are analyzed to include very significant PyC property changes during irradiation. These property changes are not included in other analyses. The most significant change is in the anisot…
Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu 2+ to Eu 3+ in various…
Abstract The kinetics of anhydride formation of poly(acrylic acid) (PAA) in porous PAA–alumina composites have been investigated by using a thermogravimetric technique (TGA). Three distinct reaction peaks at 200°C (I), 250°C (II), and 390°C (III) were identified in the dynamic TGA thermogram. These peaks were attribut…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUpper and lower bounds on the thermal conductivity of a random, two-phase materialAntonio L. DeVera Jr. and William StriederCite this: J. Phys. Chem. 1977, 81, 18, 1783–1790Publication Date (Print):September 1, 1977Publication History Published online1 May 2002Published inis…
The effects of bias voltages on the field-induced nematic-cholesteric relaxation are investigated both for samples with perpendicular boundaries and for ones with parallel boundaries, and are discussed in relation to the hysteresis behavior of texture. When the applied voltage is reduced from a value above the thresho…
The structure of paraelectric phase of Pb 5 Ge 3 O 11 was refined by the least squares calculations of single crystal neutron diffraction data at 200°C. Final R value was 0.08 and the type of phase transition was determined as displacive one. The existence of unstable oxygen atom which is lying on the mirror plane per…
Abstract Chemical and X-ray analysis of eight samples of nontronite are consistent with the Hofmann et al. montmorillonite structure. The finest fraction of some fully hydrated (15·3 Å) samples is composed of crystals all about 6 or 7 unit cells thick, and having 12 H 2 O per 8 Si, arranged at three levels in the inte…
The diatoms flora of Southern Africa No.3. Shcoeman, FR and Archibal, REM. CSIR Special report WAT 50, September 1977
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of para substituent and metal ion on rates of phenyl ring rotation in ruthenium, indium, and titanium complexes of para-substituted tetraphenylporphyrinsS. S. Eaton and G. R. EatonCite this: J. Am. Chem. Soc. 1977, 99, 20, 6594–6599Publication Date (Print):September…
A mutational leading to glutamine auxotrophy was located near a 5-fluorouracil resistance marker in the citB-thyA region of the Bacillus subtilis chromosome. This mutation resulted in a glutamine synthetase with altered kinetic and feedback properties. The specific activity of manganese-stimulated glutamine synthetase…
Facile syntheses for new 14-, 15-, and 16-membered crown compounds derived from salicylaldehyde and 5-chlorosalicylaldehyde are reported. The new compounds contain both oxygen and nitrogen heteroatoms.
Abstract The formation of X‐ray amorphous analogs of variscite and Namontebrasite was demonstrated to occur when Al 2 O 3 · n H 2 O, synthetic allophanes, and allophanic soils were reacted with sodium o ‐phosphates, Na 3‐ A H A PO 4 , of varying acidity A . The formation of the two amorphous Al‐phosphates, Al(OH) 2 H…
A pooled sample of hair was divided and portions prepared for analysis by three washing procedures, to evaluate the effect of washing procedure on the subsequent trace-element (Zn, Cu, Mg) content. The methods selected were a detergent wash, a hexane-ethanol wash, and an acetone-ether-detergent wash. For all elements,…
The X-ray procedure for estimation of the degree of crystallinity in digoxin is based upon measurement of the total X-ray scattering and the scattering from crystalline regions of the drug. The infrared procedures are based upon measurement of the peak height ratios, 1775/1618 and 3095/1618 cm-1. Correlation between r…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic exchange interactions in transition metal dimers. 11. Structural and magnetic characterization of [Ni2(tren)2(C6O4Cl2)](BPh4)2 and [Cu2(Me5dien)2(C6O4Cl2)](BPh4)2. Magnetic exchange interactions propagated by the dianions of 2,5-dihydroxy-1,4-benzoquinonesCortlandt…
Titanium‐doped α‐Al 2 O 3 exhibits a high‐temperature conductivity which is ionic at high oxygen pressures and electronic at low oxygen pressures. Both are isotropic. The temperature dependence of conductivity under conditions where equilibrium with the atmosphere is not maintained indicates both the position of the e…
The high resolution photoluminescence spectra reported here reveal new details of the structure of both bound excitons and bound multiexciton complexes in donor and acceptor doped Si. The bound exciton and bound multiexciton complexes in Si containing P impurities are found to have excited states, as was postulated in…