Materials Literature
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Abstract Poly(2,6‐dimethyl‐1,4‐phenylene oxide) has been crosslinked in the presence of large poly(dimethylsiloxane) cyclics (92 repeating units). Approximately 26% by weight of the cyclics were threaded and permanently captured by the polymer network forming a topological isomeric structure referred to as a polymeric…
Measurements of Curie temperature, magnetic moment and magnetostriction were made on Tb.3Dy.7(Fe1-xTx)1.9where T = Co and Ni (0 \leq x \leq 1for Co and0 \leq x \leq .08for Ni). Alloys were prepared using a float zone technique, from which it was possible to grow oriented [112] crystallite samples for0 \leq x \leq .21(…
This study is the first to report on the use of x-ray photoelectron spectroscopy (XPS or ESCA) for studying the surface films (less than 10 nm thick) of aged amalgams. The concentrations and electron binding energies of the elements on the surfaces of four different amalgams aged for 20 min, one day, seven days, and 3…
2,3-Dihydroporphycene 1 and 2,3-dihydroporphyrin are constitutional isomers with similar bonding behavior and similar π-electron structure. 2,3-Dihydroporphyrin is of interest, inter alia, as parent compound of chlorophyll; 1 can be obtained by hydrogenation of porphycene.
Two examples of a new class of discotic liquid crystals are presented. Their molecular architecture consists of a trisubstituted central core (either a benzene or a cyclohexane ring) and three regional cores, with three decyloxy-chains in the 3,4,5-positions of a particular benzene ring. These regional cores are linke…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThin boundary layers of the melt of a biphenyl single crystal and its premeltingA. A. Chernov and V. A. YakovlevCite this: Langmuir 1987, 3, 5, 635–640Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987ht…
Abstract The transesterification reaction of molten ethylene and vinyl alcohol copolymers (EVA), in presence of paraffinic alcohols and basic catalysts, leads to high conversion of the ester groups to secondary alcohol in both discontinuous and continuous processing equipment. Various kinds of alcohols and two differe…
Histidine decarboxylases from Klebsiella planticola and Enterobacter aerogenes were purified to homogeneity and compared with the histidine decarboxylase from Morganella morganii. All three enzymes required pyridoxal 5'-phosphate as a coenzyme, showed optimal activity at pH 6.5, decarboxylated only histidine among the…
Quantitative analysis of siliceous microfossils preserved in a radiometrically dated core from the central basin of Lake Erie (North America) shows several distinct periods in the lake's response to anthropogenic effects. Prior to European settlement of the region, microfossil deposition rates were low, and the flora…
A Ca2+/calmodulin-dependent kinase has been purified which catalyzed the phosphorylation and concomitant inactivation of both the microsomal native (100,000 Da) and protease-cleaved purified 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) (53,000 Da) fragments. This low molecular weight brain cytos…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxidation of formic acid at polyaniline-coated and modified-polyaniline-coated electrodesM. Gholamian, J. Sundaram, and A. Q. ContractorCite this: Langmuir 1987, 3, 5, 741–744Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published in…
We have performed high-resolution x-ray scattering studies of the binary liquid-crystal system of octyloxycyanobiphenyl and heptyloxypentylphenylthiolbenzoate (80CB+7\ifmmode\bar\else\textasciimacron\fi{}S5) near the nematic--smectic-A--smectic-C (NAC) multicritical point. We find that the phase diagram and smectic-or…
In thin polycrystalline gold films of four different thicknesses the average grain diameter is varied by different heat treatments. The resistivity as a function of temperature and grain diameter can be analysed satisfactorily in terms of grain-boundary scattering alone. The result is identical with experiments in whi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReductive chemistry of nickel hydroporphyrins: the nickel(I) octaethylisobacteriochlorin anionAlan M. Stolzenberg and Matthew T. StershicCite this: Inorg. Chem. 1987, 26, 19, 3082–3083Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Pub…
Abstract In the Rietveld method for the analysis of powder diffraction data the entire pattern is calculated using a model for the positions of the peaks (the unit cell parameters), their intensities (dependent on the atomic positional and thermal parameters, preferred orientation, etc.) and their widths and shapes, t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPseudoliquid behavior of heteropoly compound catalysts. Unusual pressure dependences of the rate and selectivity for ethanol dehydrationMakoto Misono, Toshio Okuhara, Tatsumi Ichiki, Takeo Arai, and Yuji KandaCite this: J. Am. Chem. Soc. 1987, 109, 18, 5535–5536Publication D…
The absorption spectra of silver sols in various stages of particle aggregation, as well as the surface-enhanced Raman scattering (SERS) excitation of citrate adsorbed on the colloid particles have been deconvoluted into a set of Gaussian bands. The absorption wavelength variation upon aggregation of the silver sols c…
X-ray measurements on liquid-crystalline main chain polymers and on combined polymers (polymers with the mesogenic groups in the main chain as well as in the side groups) before and after cross-linking allow the identification of the different liquid-crystalline phases. Smectic A, smectic B and probably smectic C phas…
In the Czochralski process a single crystal is grown from liquid in a crucible. An axial magnetic field suppresses turbulence in the melt and thus reduces the density of microdefects in the crystal. This paper treats the melt motion due to buoyancy and thermocapillarity. The magnitude of this motion decreases roughly…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of boron nitride ceramics from poly(borazinylamine) precursorsChaitanya K. Narula, Riley Schaeffer, Robert T. Paine, Abhaya Datye, and William F. HammetterCite this: J. Am. Chem. Soc. 1987, 109, 18, 5556–5557Publication Date (Print):September 1, 1987Publication His…