Materials Literature
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Abstract The quantification of the relative mineralogical composition of clay mixtures by powder X-ray diffraction or chemical mass balance methods has been severely hampered by a lack of representative standards. The recent development of elemental mass balance models that do not require standards for all minerals in…
The electronic structures and the ligand affinities of several nickel porphyrins with different types and degrees of macrocycle deformations have been studied by magnetic circular dichroism (MCD) spectroscopy. The nickel porphyrins studied in this work are nickel(II) octaethylporphyrin (NiOEP) with a mixture of planar…
Abstract The kaolin surface was modified through surface reaction in order to tailor the colloidal behaviour of the particles. A molecular weight series of polyethylene glycols was attached to the surface hydroxyls, using a urethane linker, by reaction with toluene 2,4‐diisocyanate. The change in the surface was monit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeteroatomic Effects on the Acid-Catalyzed Rearrangements of Dispiro[4.0.4.4]tetradeca-11,13-dienesBruce M. Branan and Leo A. PaquetteCite this: J. Am. Chem. Soc. 1994, 116, 17, 7658–7667Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Pub…
Abstract Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were conducted on two common types of rye straws (Danko and Kustro) at a heating rate of 20°C/min in an oxidizing atmosphere (15% oxygen and 85% nitrogen, by volume) between ambient temperature and 700°C. The two step nature of the TGA c…
Characteristics of shallow n‐type layers formed by direct doping of phosphorus from the vapor phase are presented. Shallow doped layers can be formed with depths less than 100 nm using PH 3 as a source gas and hydrogen as a carrier gas. It is found that the phosphorus concentration on the surface is constant with the…
Future trends and recent developments of reinforcing materials and fabrication processing for advanced metal matrix composites are discussed in this paper. A national R & D project is currently underway to improve the oxidation resistance and heat resistance to 1773 K of continuous ceramics Si-Ti-C-O fibers (Tyranno f…
Abstract Shaped charge craters can be calculated in regards to depth and diameter profile using the SDM model named after Simon, DiPersio, and Merendino( 3 ). Crater profiles calculated using the SDM formulae exhibit a systematic deviation if compared with test data from firings of certain MBB (now DASA) shaped charge…
Abstract The dielectric characteristics of cyanoethylated cellulose samples having different degrees of substitution have been investigated at different frequencies from 0.1 to 10 KHz and at temperatures from −40°C to 180°C. Two relaxation processes, designated as α and β in order of decreasing temperature, were recog…
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…