Materials Literature
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The well known, extremely reactive [18]annulene 1 and the hypothetical isomer 2 should be capable of being stabilized by CH2- and CHCH-groups as internal and external bridges, respectively. The corresponding hydrocarbons, 3 and 4, are still unknown, although they are of great interest as links between the non-natural…
The doping and undoping characteristics of alkali‐metal doped polyacetylene are investigated using cyclic voltammetry and complex impedance measurement techniques. Reversibility, charge transfer resistance , double layer capacitance , and general impedance behavior are discussed.
Ceramic powders containing dispersed inert particulates often exhibit dramatically lower densification rates than the pure powder. This decrease results from the shrinkage incompatibilities of the matrix and the inclusion during densification. The analyses of this phenomenon all predict that the shrinkage rate is only…
The presented data are the result of a reappraisal of the biocompatibility properties of titanium alloys. An in vitro study has been conducted using Hanks' solution with four different additional compounds (EDTA, l-leucine, Na-citrate, and 8-hydroxyquinoline). A measurable dissolution rate was observed for Ti and Al i…
Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.
To examine the conformation of polyanilines with different degrees of oxidation two three-ring oligomers, N-N′-diphenyl-1,4-phenylenediamine (the ‘‘amine trimer’’) and N-N′-diphenyl-1,4-benzoquinodiimine (the ‘‘imine trimer’’) have been studied. The amine and imine trimers are model molecules for leucoemeraldine and p…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, NMR characterization, and electrical properties of siloxane-based polymer electrolytesRalph Spindler and D. F. ShriverCite this: Macromolecules 1988, 21, 3, 648–654Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissu…
Films of polyimide (>8 nm) were formed on a polycrystalline silver surface following heating of a vapor-deposited layer of 4,4,-oxydianiline (ODA) and 1,2,4,5-benzenetetracarboxylic anhydride (PMDA). The imidization reaction leading to polymer formation was followed in situ with X-ray photoelectron spectroscopy. Th…
The effects of high temperatures on polymer‐derived Nicalon and chemically vapor‐deposited (CVD) SiC fibers have been investigated by mass‐spectrometric vapor pressure studies and by SEM observations of exposed fibers. Vaporization is kinetically limited for both materials; the predominant species vaporizing from Nica…
Clean polyimide films spin-coated onto gold substrate have been fully characterized by high resolution electron energy loss spectroscopy (HREELS): 19 electron-induced vibrational bands could be resolved and assigned by comparison with IR spectroscopy. The attribution of these peaks constitutes a firm and necessary bas…
Abstract not Available.
Quarter-micrometer gate-length high-electron-mobility transistors (HEMTs) for cryogenic low-noise application with very low light sensitivity have been developed. At room temperature, these exhibit a noise figure of 0.4 dB with associated gain of 15 dB at 8 GHz. At a temperature of 12.5 K the minimum noise temperature…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic and spectroscopic characterization of an iron porphyrin peroxide complex. Peroxoferrioctaethylporphyrin(1-)Judith N. Burstyn, James A. Roe, Andrew R. Miksztal, Ben A. Shaevitz, George. Lang, and Joan Selverstone. ValentineCite this: J. Am. Chem. Soc. 1988, 110, 5, 1…
Abstract Synthetic hydrotalcite, Mg6Al2(OH)16CO3·4H2O, and its analogues were synthesized, heat-treated at 773 K, and used as catalysts for the title reaction to form methyl vinyl ketone (MVK) at 673 K. MVK was formed over all the catalysts examined, the highest MVK yield (20% on acetone basis) being found over the he…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural characterization by EXAFS spectroscopy of the binuclear iron center in protein A of methane monooxygenase from Methylococcus capsulatus (Bath)Agneta. Ericson, Britt. Hedman, Keith O. Hodgson, Jeffrey. Green, Howard. Dalton, James G. Bentsen, Robert H. Beer, and St…
Abstract The crystal structures of an organic superconductor (BEDT-TTF)2Cu(NCS)2 (Tc=10.4 K) at 298 K and 104 K are determined by X-ray analysis. The packing pattern of donors is nearly analogous to κ-(BEDT-TTF)2I3. The counter anion, Cu(NCS)2−, has no positional disorder and constructs a peculiar sheet where a copper…
A newly defined chick calvariae osteoblast culture system that undergoes a temporal sequence of differentiation of the osteoblast phenotype with subsequent mineralization (Gerstenfeld, L. C., S. Chipman, J. Glowacki, and J. B. Lian. 1987. Dev. Biol. 122:49-60) has been examined for the regulation of collagen synthesis…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular and macromolecular nonlinear optical materials. Probing architecture/electronic structure/frequency doubling relationships via an SCF-LCAO MECI .pi. electron formalismDe Quan. Li, Mark A. Ratner, and Tobin J. MarksCite this: J. Am. Chem. Soc. 1988, 110, 6, 1707–171…
We have grown diamond crystals and polycrystalline diamond films from CH4/H2/O2 gas feeds in a simple, high-power density, 2450-MHz discharge tube reactor. Single-crystal growth rates over 20 μm/h have been achieved. The material has been analyzed using Raman spectroscopy, Auger spectroscopy, and x-ray diffraction. Co…
Abstract An attempt is made to give a survey of polymer processing during the past 50 years, with a backward glance to earlier periods and to roots of development in related branches of industrial production. Selected topics are treated in some detail, with comments and comparisons, showing typical trends and forecast…