Materials Literature
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We have used molecular orbital calculations to investigate effects of environmental substances and strain on fracture of the Si─O bond in an H 6 Si 2 O 7 molecule. We believe that the tendencies observed simulate crack growth in silica in the vicinity of a crack tip. This study is focused on the initial Stage of envir…
Abstract The interaction energies between PS, Pα‐MS, and PMMA, as well as acrylonitrile and maleic anhydride units, with a series of polysulfones were quantitatively determined from oligomer/oligomer, oligomer/homopolymer, and homopolymer/copolymer blends. Interaction energies were calculated from the Flory‐Huggins th…
Abstract Poly(l- and d-lysine)s (l- and d-1, respectively) were modified with a phenylboronic acid derivative which acts as a sugar-binding site. When monosaccharides were added to the l-1 solution, the helix content was increased and the pH which gives the maximum helix content shifted to lower pH region. The pH depe…
Chrysotile formation arises through serpentinization of ultramafics and silicified dolomitic limestones. Rock types tend to control the trace metal content and both the nature and amounts of admixed minerals in the ore, such as fibrous brucite (nemalite) and tremolite. Some associated minerals and trace metals are tho…
Abstract The single‐stage preparation of poly[2,2′‐( m ‐phenylene)‐5,5′‐bibenzimidazole] (PBI), from 3,3′,4,4′‐tetraaminobiphenyl (TAB) with isophthalic acid (IPA) in the presence of a catalyst, was explored and developed. The effects of a variety of catalysts on the polymerization of TAB with IPA and/or diphenyl isop…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyaniline Fibers, Films, and Powders: X-ray Studies of Crystallinity and Stress-Induced Preferred OrientationJ. E. Fischer, Q. Zhu, X. Tang, E. M. Scherr, A. G. MacDiarmid, and V. B. CajipeCite this: Macromolecules 1994, 27, 18, 5094–5101Publication Date (Print):August 1,…
A new method of osmium conductive metal coating for scanning electron microscopy specimens using osmium tetroxide in direct current glow discharge and its apparatus have been devised. Anode and cathode plates are placed in a gas reactor, sublimated osmium tetroxide is introduced, and glow discharge is generated. As a…
The performance of the gaseous precursor diethyl-tellurium (DETe) for n-type doping of GaAs is studied. We report on both the properties of the molecular source DETe as well as on the suitability of the dopant element tellurium. Te is found to be an excellent dopant, comparable to Si in the lower-doping regime and sup…
We report on experimental results on the dynamical behavior of the stress relaxation in a model system for earthquakelike dynamics. In the experiments, a continuous elastic medium, namely, a transparent gel, is sheared at a very slow rate in between two coaxial circular cylinders. The stress relaxations are investigat…
Abstract A very simple technique is proposed for a quantitative or semiquantitative interpretation of X-ray diffraction (XRD) patterns for two-component mixed-layer structures. It is suitable for a determination of the Reichweite (R) values and proportions of component layers from graphical simulations of basal peak p…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAutoacceleration in Free Radical Polymerization. 2. Molecular Weight DistributionsBen O'Shaughnessy and Jane YuCite this: Macromolecules 1994, 27, 18, 5079–5085Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Published inissue 1 August 199…
The importance of supersaturation in the dynamics of apatite precipitation from aqueous solutions is well-established. To determine whether this parameter has a comparable impact on the concomitant development of the textural properties of this phase, such as crystal size and shape, we investigated mineral accretion i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystalline Zwitterionic Stilbazolium Derivatives with Large Quadratic Optical NonlinearitiesChristophe Serbutoviez, Jean-Francois Nicoud, Jean Fischer, Isabelle Ledoux, and Joseph ZyssCite this: Chem. Mater. 1994, 6, 8, 1358–1368Publication Date (Print):August 1, 1994Public…
Summary The ability of Mozzarella cheese to stretch and form long fibres was evaluated by two simple instrumental tests. The first test, which was basically a tensile test, resembled the way the consumer assesses the stretchability of cheese as a pizza topping. The extensibility measurements of the test correlated wel…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of Brush Polydispersity on the Interphase between End-Grafted Brushes and Polymeric MatrixesCharles F. Laub and Jeffery T. KobersteinCite this: Macromolecules 1994, 27, 18, 5016–5023Publication Date (Print):August 1, 1994Publication History Published online1 May 2002P…
Abstract The corona discharge technique was explored as a means of forming chemically active sites on cellulose surfaces. Paper thus treated was brought into contact with the reaction medium, a styrene–methanol mixture. The corona discharge was generated between two flat circular electrodes separated by a quartz disk.…
Abstract The effect of temperature (from 296 to 423 K) upon the absorption and fluorescence of l-phenyl-4-diphenylthiophosphinyl butadiene (PDPB) and of the direct irradiation on the absorbance were investigated in poly(vinyl alcohol) film. It was found that for PDPB in PVA film the transition from cis to trans config…
We studied the dielectric behavior in the ferroelectric SmC * and ferrielectric SmC γ * phases of the antiferroelectric liquid crystal (R)-1-methylheptyl-4-( 4 ′′ -n-dodecyloxybiphenyl- 4 ′ carbonoyloxy)-3-fluoro-benzoate. In the SmC γ * phase, 3 dielectric relaxations were recognized in the frequency range under cons…
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Abstract Treatment with a mixture of formic and hydrobromic acids converted ethyl 3,4‐diethyl‐5‐methyl‐pyrrole‐2‐carboxylate 7a to 3,3′,4,4′‐tetraethyl‐5,5′‐dimethylpyrromethene hydrobromide 8a presumably via the condensation of α‐unsubstituted and α‐formylpyrrole intermediates 7c and 7e formed in situ. The correspond…