Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new synthetic approach to poly- and perfluorinated polyethersMing H. Hung, William B. Farnham, Andrew E. Feiring, and Shlomo RozenCite this: J. Am. Chem. Soc. 1993, 115, 20, 8954–8959Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Publ…
Polymeric fibers were produced from a polyaluminocarbosilane obtained by reacting polycarbosilane and an aluminum alkoxide modified with a β‐ceto ester. The pre‐ceramic fibers were converted into amorphous Si‐Al‐O‐N ceramic fibers after a pyrolysis process under flowing ammonia at 1000°C. 29 Si and 27 Al magic‐angle s…
For 65 years it has been discussed whether hexatungstate ions exist. Now the confirmation of their existence and the structural analysis of Na5[H3W6O22] · 18H2O have been achieved; in aqueous solution the latter is probably in equilibrium with the known [W7O24]6− ion. The polyhedral representa tion of the structure of…
The X-band electron paramagnetic resonance study of Er-doped Bi4Ge3O12 single crystals at 5 K is reported. The spectra have been attributed to Er3+ ions in the Bi3+ site, confirming the assumed trigonal site symmetry of Er3+ in previous crystal-field analysis. A detailed study of the measured g-factor values indicates…
Preliminary results of ongoing crack growth studies being performed on an API X-65 line pipe steel in a low-pH cracking environment were reported. Objectives were to reproduce low-pH crack propagation in the laboratory, to identify a crack driving force parameter, and to evaluate the influence of environmental and mec…
RATIONALE AND OBJECTIVES: The purpose of this study was to further develop and compare manganese-based liposomes prepared by two different approaches wherein a manganese ion was entrapped within the internal aqueous space of the vesicles or into the bilayer surface via membrane bound complexes. METHODS: Small unilamel…
The polarized Raman spectra of γ-substituted propyl-trialkoxysilanes [Formula: see text] have been recorded, and an assignment is proposed. The spectra are briefly discussed with emphasis on the glycidoxy compound (IV). Micro-Raman data are also given for the co-condensation product of a 5:95 mixture of III and IV. Th…
Abstract Novel aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from 1,5‐bis(4‐aminophenoxy)naphthalene (APN) and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that included ring‐opening polyaddition in a polar solvent such as N , N ‐dimethylacetamide (DMAc)…
Dielectric properties of TFMHPOBC, 3MC2PCPOPB and TFMHBOPP which indicate different phase sequences have been investigated as functions of temperature and dc bias field. In the antiferroelectric phase under no bias field, relaxations due to the soft mode and molecular rotation around the short axis are observed. The s…
We present nanosecond hole-burning experiments for CdSxSe1−x and CdSe quantum dots grown in a glass matrix; we compare the results for different precipitation stages. For the first time to our knowledge a drastic sharpening of the spectral holes with a half-width as low as 10 meV has been found to be typical for the s…
Kinetic measurements have been made on the degradation reaction of electrochemically prepared polypyrrole films. The measurements were made by applying proper potentials at polymer film covered electrodes in aqueous sulfuric acid solutions and monitoring the absorbance of the electrolysis product as a function of time…
The Monte Carlo method is applied to investigate the asymptotic behavior of self-avoiding polymerized membranes. We use a model described by a local Hamiltonian: repulsive interactions (hard spheres of diameter \ensuremath{\sigma}) act only between atoms whose degree of neighborhood (measured along the membrane) does…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeterometal dependence of electron distributions and redox potentials in clusters with cubane-type [MFe3S4]2 coresWei Cen, Sonny C. Lee, Jiguo Li, Frederick M. MacDonnell, and R. H. HolmCite this: J. Am. Chem. Soc. 1993, 115, 21, 9515–9523Publication Date (Print):October 1,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRegiochemically and stereochemically defined synthesis of allylsilanesShinji Marumoto and Isao KuwajimaCite this: J. Am. Chem. Soc. 1993, 115, 20, 9021–9024Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Published inissue 1 October 1993h…
Facilitation of protein folding by GroEL usually requires involvement of GroES and ATP. In their absence nascent proteins tend to be arrested on GroEL or, if released, fail to show enhancement of reactivation yield relative to that observed without the chaperonin. In contrast, the yield of reactivation of glucose-6-ph…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of substitution of the median thiophene ring on the electrodeposition and structure of poly(terthienyls)Jean Roncali, Alain Gorgues, and Michel JubaultCite this: Chem. Mater. 1993, 5, 10, 1456–1464Publication Date (Print):October 1, 1993Publication History Published…
Abstract The phase behaviour and the related morphology of the system high‐density polyethylene/diphenyl ether was investigated. A liquid‐liquid demixing precedes the crystallization in solutions with polymer weight fractions lower than 0,30. A three‐phase equilibrium is installed, in which two liquid phases with diff…
An innovative, short‐term corrosion test has been developed that can predict long‐term copper corrosion behavior. When used in a six‐day study of uniform copper corrosion in five waters, the test predicted corrosion rates that were in good qualitative and quantitative agreement with known long‐term (210‐day) results.…
Alumina‐glass composites were prepared by a melt‐infiltration process that is similar to a fabrication method for dental crowns and bridges. Cylindrical alumina samples with green densities ranging from 62% to 72% of theoretical were formed by slip casting followed by sintering at 1100°C for 2 h. A borosilicate glass…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLiquid-crystalline characteristics of site-selectively-modified chitosanDeeleep K. Rout, Satish K. Pulapura, and Richard A. GrossCite this: Macromolecules 1993, 26, 22, 5999–6006Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Published i…