Materials Literature
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Many forms of chemical bonding are exhibited by Al in intermetallic and Zintl phases. This is revealed by the calculation of the electron localization function for the series Al, CaAl 2 , SrAl 2 , BA1 4 , CaAl 2 Si 2 , and Si. With this procedure it is possible to distinguish clearly between metallic, covalent multice…
Abstract Transition metal chemistry contains a class of complex compounds for which the spin state of the central atom changes from high spin to low spin when the temperature is lowered. This is accompanied by changes of the magnetic and optical properties that make the thermally induced spin transition (also called s…
Ce-containing chalcogenides may exhibit interesting chromatic properties due to the presence of a CeIII-5f/CeIII-4d gap. In such insulating materials, color varies from red to yellow depending on the covalent character of the Ce–S bond. Thanks to this correlation, a continuous modification of the Ce–S bond characteris…
The localized excitations in the competing bond-order-wave(BOW), charge-density-wave(CDW), and spin-density-wave(SDW) systems are investigated within the Bogoliubov-de Gennes formalism using an extended Peierls-Hubbard model. An extensive study of localized excitations over a wide range of the on-site e-ph coupling λ2…
A series of reactor design studies based on the Tokamak configuration have been carried out under the direction of Professor Robert Conn of UCLA. They are called ARIES-I through IV. The key mission of these studies is to evaluate the attractiveness of fusion assuming different degrees of advancement in either physics…
Fatigue‐crack growth behavior under cyclic tension‐tension loading has been examined in a 30‐vol%‐TiB 2 ‐reinforced β‐SiC matrix composite, using compact tension specimens tested at temperatures from 750° to 850°C in a furnace air environment. Cyclic fatigue‐crack growth rate was found to depend strongly on testing te…
Abstract Crosslinked 1,4-poly butadiene (BR) and styrene-butadiene rubber (SBR) were oxidized in various ionic environments (water, neutral salt solutions, acidic and basic buffers). The acceleration of oxidation when the elastomer was immersed in neutral and basic aqueous solutions, compared to dry air, is consistent…
Potentiometric evalution of the interaction between aluminium(III) and the hydroxy carboxylates 3-deoxy-D-ribo-hexonate (L1H) and 2,5-dihydroxypentanoate (L2H) provided evidence for the formation of 1:1 complexes only, though with the ligand being present in singly, doubly and quadruply deprotonated forms in the hexon…
Abstract The autoignition temperature and composition of 15 carbon‐filled fluoroelastomers have been determined. These experimental data and three sets of literature data are used to examine the relationship between autoignition temperature and rubber composition. The autoignition temperature at an elevated oxygen pre…
The formation and evolution of the gap states formed with increasing Cs concentration in thin 6P films are followed with ultraviolet photoemission spectroscopy (UPS) and indirectly with energy loss spectroscopy involving electronic transitions (EELS). Two distinct doping regimes are apparent, in the lower doping regim…
Since the introduction of poly(ethy1ene terephthalate) (PET) and polyamide 6, many attempts have been made to synthesize other polymers with a large variety of properties. One of the polymers which has been studied extensively is polypivalolactone (PPVL), formed by ring-opening polymerization of pivalolactone (PVL). P…
Abstract A simple Ar neutral beam gun capable of providing low‐energy Ar atoms has been developed for surface cleaning and depth profile analysis in x‐ray photoelectron spectroscopy, Auger electron spectroscopy, etc. Characterization of the Ar neutral beam gun is described. The effect of neutral beam bombardment was i…
In this paper, ferroelectric PbTiO3 (PT) ultrafine powders with nanosized grains are prepared through sol-gel and hydrolysis-aging process. The lattice constants and grain size are determined by XRD analysis. The phase transition is examined by DSC and Second Harmonic Generation (SHG) measurements. The relation betwee…
The morphology of diamond films deposited in the substrate temperature range of 550° C to 750° C by microwave plasma enhanced chemical vapor deposition (MPECVD) has been investigated as a function of the nucleation density. Nucleation density can be controlled in the range of 1.5×10 7 to 1.0×10 10 nuclei/cm 2 by varyi…
PZT thin films have been prepared via a sol-gel route using standard butoxide and acetate precursors. The solution compositions were modified by the addition of acetylacetone in 2 methoxyethanol, which has the effect of changing the solution complex and therefore its deposition and drying characteristics. Varying amou…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLight-Scattering Studies on Hydrogen-Bonded Polymer BlendsDorab E. Bhagwagar, Paul C. Painter, and Michael M. ColemanCite this: Macromolecules 1994, 27, 24, 7139–7145Publication Date (Print):November 1, 1994Publication History Published online1 May 2002Published inissue 1 No…
Abstract The effect of potassium aluminium sulphate, (hereafter referred to as alum) on the energy of pyrolysis/combustion of wood cellulose was investigated using thermogravimetric analysis (TGA). It was observed that the energy of pyrolysis of all the materials employed increases with flame retardant loading. Hence,…
3-Oxo-delta 5-steroid isomerase (KSI) catalyzes the isomerization of a variety of 3-oxo-delta 5-steroids to their conjugated delta 4-isomers through the formation of an intermediate dienol. Mutation of the catalytic base (Asp-38) to Glu (D38E) has been found to reduce kcat/Km for the isomerization of 5-androstene-3,-1…
Abstract Auger electron spectroscopy measurements have been performed on silicon nitride layers exposed to air. The layers were deposited on Si(100) wafers kept at 300°C or 600°C by excimer laser ablation of a silicon target under various ammonia pressures. The Si LVV, O KLL and N KLL lineshapes of silicon nitride lay…
Abstract A useful instrument for polymer film preparation by solution casting was employed in this study. It enabled us to control the solvent evaporation rate of the polymer solution. By using this instrument, the aggregation of hard segments in segmented poly(urethane‐urea) (SPUU) was investigated. SPUU was prepared…