Materials Literature
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Abstract Auger electron spectroscopy has been used to characterize the oxidation of polycrystalline zirconium in an oxygen atmosphere at low pressures (10 −8 ≤ P ≤ 10 −5 Torr) and room temperature after cleaning the surface by Ar + ‐ion bombardment. Quantitative analysis of the oxidation process was performed by using…
Stress relaxation measurements in tension have been made on nitrile rubber vulcanizates containing short jute fibers. The effects of strain level, bonding system (silica-resorcinol-hexa), fiber orientation, fiber content, temperature, and prestraining on the rate of stress relaxation have been investigated. Existence…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe question of Friedel-Crafts transformylations. Acid-catalyzed reactions of aromatic aldehydes with arenesRoyston M. Roberts, Ahmed M. El-Khawaga, Kevin M. Sweeney, and Maher F. El-ZohryCite this: J. Org. Chem. 1987, 52, 8, 1591–1599Publication Date (Print):April 1, 1987Pu…
Two phase transitions have previously been identified in ${\mathrm{K}}_{3}$${\mathrm{Cu}}_{8}$${\mathrm{S}}_{6}$, a second-order transition at 153 K and a first-order transition at 55 K. In this x-ray scattering study we show that the 153-K transition, which is associated with a decrease in the conductivity, correspon…
Abstract A monoclinic II b -2 clinochlore from Washington, D.C., contrary to previous studies, is primarily a ferroan rather than a ferrian chlorite. Disorder of tetrahedral Si,Al cations is indicated because of unsuccessful structural refinements in subgroup symmetries. The true space group is C 2/ m . Slight orderin…
Polymerization of pyrrole occurred on an irradiated surface of n ‐ TiO 2 semiconductor electrode in aqueous solutions of pyrrole, when the electrode potential was set between −0.6 and +1.5V vs. SCE. The conductivity of deposited polypyrrole film (as grown, in the doped state) was ca. 1S cm −1 . Electrochemical undopin…
Microstructural evolution of a 7.8 mol% Ca‐PSZ, fired at 1870°C and subsequently aged at 1300°C, was studied and correlated with the mechanical properties. The morphology, rafting, and subsequent coarsening of the tetragonal ( t ) ZrO 2 precipitates were of particular interest, as was the instability of some of the t…
It is shown that the degradation of XLPE, resulting from its exposure to partial discharges, leads to the formation of solid, liquid and gaseous products that result directly from the discharge synthesis reactions taking place within the intervening electrode gap space. The prime reagents in the discharge synthesis pr…
Abstract Trifunctional hydroxy‐terminated oligomeric polyesters, M n 500, 1000, and 2000, were prepared by initiating ring‐opening copolymerization of δ‐valerolactone and ε‐caprolactone with glycerol. The prepolymers were converted to crosslinked polyester‐urethanes by their reaction with hexane‐1,6‐diisocyanate in pr…
Abstract This article reveals the diverse nature of runaway systems as well as some general trends. In addition, it also serves to point out the usefulness of such an apparatus in characterizing virtually unknown systems.
Ultrafine ferrites, {MFe_2O_4} where M = Mg, Mn, Fe, Co, Ni, and Zn, were prepd. by the combustion/decompn. in a melt of solid soln. precursors, hydrazinium metal hydrazinecarboxylate hydrates, {N_2H_5M_1}/{3Fe_2}/{3(N_2H_3COO)}3.{H_2O} (M = Mg, Mn, Fe, Co, Ni, and Zn). The precursors decomp. at low temps. (75-200°) w…
Kerr electro-optic field mapping measurements are presented in electron beam irradiated polymethylmethacrylate (PMMA) where the accumulated trapped charge results in large self-electric fields of the order of 1 to 2.5 MV/ cm. The resulting numerous light maximum and minimum recorded on photographic film and videotape…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIsotope and temperature dependence of transition-metal shielding in complexes of the type M(XY)6Cynthia J. Jameson, Dieter Rehder, and Martin HochCite this: J. Am. Chem. Soc. 1987, 109, 9, 2589–2594Publication Date (Print):April 1, 1987Publication History Published online1 M…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear relaxation in the magnetic coupled system Cu2Co2SOD. Histidine-44 is detached upon anion bindingL. Banci, I. Bertini, C. Luchinat, and A. ScozzafavaCite this: J. Am. Chem. Soc. 1987, 109, 8, 2328–2334Publication Date (Print):April 1, 1987Publication History Published…
The authors present self-consistent band-structure calculations of HCP Be made by means of the full-potential linearised-augmented-plane-wave (LAPW) method and on the basis of the local density approximation. In contrast to earlier calculations no shape approximations for the charge density or the potential are made a…
Paramagnetic complexes of manganese(II), iron(III), and gadolinium(III) with many ligands appear to undergo ligand substitution in vivo, producing biodistribution data similar to the hydrated metal ions. To identify ligands likely to be valuable in the preparation of paramagnetic contrast agents, a series of aminopoly…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAcid-mediated trans-cis isomerization of substituted tetrathiafulvalenes. Selective precipitation of the trans isomerAbdelaziz Souizi, Albert Robert, Patrick Batail, and Lahcene OuahabCite this: J. Org. Chem. 1987, 52, 8, 1610–1611Publication Date (Print):April 1, 1987Public…
Abstract Self aggregation of 4,4′,4″,4'″-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis[1-methylpyridinium] cation (TMPyP4+) in water has been verified by means of fluorescence and 1H NMR spectroscopy. The novel fluorescence behavior of TMPyP such as extraordinarily red-shifted Q(0-0) fluorescence band, blue shift of t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVibrational spectra of carboxylate complexes. VII. Partial valence trapping in a trinuclear mixed-valence iron(III,III,II) cluster: vibrational spectra of [Fe3O(OOCCH3)6L3] and related mixed-metal complexesL. Meesuk, U. A. Jayasooriya, and R. D. CannonCite this: J. Am. Chem.…
Cytochrome c oxidase contains four redox-active metal centers: two heme irons, cytochromes a and a3, and two copper ions, CuA and CuB. Due to the paucity of spectroscopic signatures for both copper sites in cytochrome c oxidase, the ligands and structures for these sites have remained ambiguous. The specific depletion…