Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImproved metalation of 2,4,6-tribromoanisole: synthesis of 2-methoxyresorcinolKenneth GreenCite this: J. Org. Chem. 1991, 56, 13, 4325–4326Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://pubs.acs.org/doi…
The nitridation kinetics of Si powder compacts were studied by measuring the flow rate dependence of N 2 and N 2 –H 2 gas mixtures during slow heating of Si compacts while simultaneously monitoring the oxygen partial pressure of the egress gas. The reaction was found to occur in two distinct stages. In pure nitrogen t…
Abstract Fragmentation of support/catalyst particles during propylene bulk polymerization is analyzed by means of a mathematical model including energy and mass balances, with chemical reaction. The rupture phenomenon is specifically considered by the model and analyzed as it proceeds along time. Model predictions con…
Abstract A comparative study of the effects of catalyst fragmentation in the gas phase and bulk polymerization processes in performed. Typical operating conditions for each process are used for the comparison. The monomer concentration in the bulk process is nearly one order of magnitude larger than that in the gas ph…
Abstract Polyphosphate esters containing ferrocene structures were synthesized from 1,1′‐bis ( p ‐hydroxyphenylamido) ferrocene and 1,1′‐bis ( p ‐hydroxyphenoxycarbonyl) ferrocene with aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by infrar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDeconvolution of x-ray diffraction data to elucidate plastic deformation mechanisms in the uniaxial extension of bulk nylon 6A. Galeski, A. S. Argon, and R. E. CohenCite this: Macromolecules 1991, 24, 13, 3945–3952Publication Date (Print):June 1, 1991Publication History Publ…
Equilibrium axial-radial director fields of a nematic liquid crystal confined to micrometer cylindrical cavities are examined in the approximation of one elastic constant K and spatially homogeneous nematic order parameter. It is shown that, in the strong-anchoring regime with homeotropic boundary conditions, a metast…
The combined build-up and attenuation factor, B exp (-mu r), of point isotropic photon sources in a water medium has been calculated using the Monte Carlo method, for energies (20-1500 keV) and distances (1-10 cm) relevant in brachytherapy. For the transport of photons and electrons, up-to-date and self-consistent tot…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPorphyrins-cyclodextrin. 2. Dissociation, reduction, and proton relaxivity of an iron(III) porphyrin .mu.-oxo dimer in cyclodextrin solutionsS. Mosseri, J. C. Mialocq, B. Perly, and P. HambrightCite this: J. Phys. Chem. 1991, 95, 12, 4659–4663Publication Date (Print):June 1,…
The electrochemical properties of anodically electrodeposited iridium oxide films are investigated for application to transmittance variable cells. The reactivity of electrochromic reaction of the film increases with the increase in water content in LiClO 4 propylene carbonate electrolyte, and decreases with increasin…
Copper foils for a Raman study were prepared by a chemical etching method with HNO 3 . These foils were found to exhibit a strong SERS effect. SERS or SERRS spectra of cobalt phthalocyanine, cystamine dihydrochloride, benzylamine, and p-thiocresol have been taken to illustrate the usefulness of this sample preparation…
Stabilization of an oxyanion transition state is important to catalysis of peptide bond hydrolysis in all proteases. For subtilisin BPN', a bacterial serine protease, structural data suggest that two hydrogen bonds stabilize the tetrahedral-like oxyanion intermediate: one from the main chain NH of Ser221 and another f…
In vitro enzymatic degradation of non-porous films of segmented poly(ether urethane) (Pellethane 2363-80AE) was investigated by incubating the biomaterial in concentrated trypsin solutions for 5 months at room temperature. Chemical degradation of films was monitored by surface analysis techniques such as Fourier trans…
Work hardening of single-phase crystalline materials (and to some extent, coarse two-phase and dispersion hardened materials too) at low temperatures results from the competition of two dynamic processes: dislocation accumulation, during the long-range gliding of mobile dislocations and dynamic recovery, involving loc…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTrinuclear, oxo-centered mixed-valence iron complex with unprecedented carboxylate coordination: [Fe3O(O2CCH3)6(TACN)].cntdot.2CHCl3Peter Poganiuch, Shuncheng Liu, Georgia C. Papaefthymiou, and Stephen J. LippardCite this: J. Am. Chem. Soc. 1991, 113, 12, 4645–4651Publicatio…
The authors describe a series of experiments to study prebreakdown spacer charging and subsequent flashover in a compressed gas insulated rod-spacer-plane system under positive impulse voltages. Prebreakdown corona is identified as the most likely source for spacer charging. Surface charges were measured in situ with…
The objective of this study was to test the hypothesis that tempering stress can retard the growth of surface cracks in layered porcelain discs with variable levels of contraction mismatch. Porcelain discs, 16 mm in diameter and 2 mm thick, were prepared with a 0.5-mm-thick layer of opaque porcelain (0) and a 1.5-mm-t…
Abstract Time‐resolved studies of network self‐organization from homogeneous solutions of the representative biostructural polymer agarose are presented. Solutions are temperature quenched and observed by several techniques. Consistent with previous suggestions by the authors, experiments at concentrations up to about…
We apply a density-functional formalism to a system of hard spherocylinders and obtain a phase diagram including the isotropic, nematic, and smectic-A phases. The nematic--smectic-A transition can be of either first or second order, and the tricritical point is located at a length-to-diameter ratio L/D=5.9. The coexis…
Based on thermodynamic predictions that, in the gas‐phase system AlCl 3 /NH 3 , AlN can be produced up to the theoretical yield, the performance of a chemical vapor deposition (CVD) reactor suitable for continuous powder production is investigated. Under the applied reaction conditions and reactor configuration, fine…