Materials Literature
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Specific surface area and longitudinal wave ultrasonic velocity were measured in zinc oxide (ZnO) powder compacts partially sintered to different pore fractions ( P ). A linear correlation was observed between the reduction in surface area and the increase in ultrasonic velocity at all P up to the onset of pore closur…
Composite hydrogels of poly(acrylic acid) (PAA) and poly-(methyl metacrylate) (PMMA) reinforced with a bioceramic, TiO2, have been prepared by reactive moulding from a mixture of the bioceramic with PMMA beads and acrylic acid. Cylindrical specimens with various TiO2-polymer compositions, but a constant 3:1 PAA/PMMA r…
Various water-soluble polysulphonated and polycarboxylated porphyrins and some of their metallated derivatives have been prepared and their antiviral properties against human immunodeficiency virus (HIV-1, HIV-2), simian immunodeficiency virus and other viruses are reported. Besides these polyanionic compounds, two ne…
The activation of CH 4 over NiO/MgO was investigated via temperature-programmed reaction mass spectroscopy (TPR-MS). Over pure MgO, CH 4 is not activated, while over pure NiO, CH 4 is activated to CO 2 around 660 °C. There are two kinds of CH 4 activations over the NiO/MgO solid solution catalysts prepared by the impr…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTFractionation and Characterization of Microbial Polyesters Containing 3-Hydroxybutyrate and 4-Hydroxybutyrate Repeat UnitsFengying Shi, Richard D. Ashby, and Richard A. GrossView Author Information Department of Chemistry, Universit…
Abstract In this theoretical study, we investigate the molecular and electronic structures of symmetrical and unsymmetrical squaraine dyes. Such dyes can be represented by the formula D‐A‐D, where D is a donor group and A an acceptor moiety. We analyze the evolution in geometric structure that results from changing bo…
Composite hydrogels of poly(acrylic acid) (PAA) and poly-(methyl metacrylate) (PMMA) reinforced with a bioceramic, TiO2, have been prepared by reactive moulding from a mixture of the bioceramic with PMMA beads and acrylic acid. Cylindrical specimens with various TiO2-polymer compositions, but a constant 3:1 PAA/PMMA r…
A porous α-alumina tube of 2.4 mm o.d. with an average pore size of ca. 150 nm was coated with p-xylene solutions of polycarbosilane (PC) and polystyrene (PS). The weight fraction of PS to total solid mass (PC + PS) was varied as 0, 1, 3 and 5 wt% (denoted as PC-PSx for a solution of x wt%). Then the film was cured in…
Two mutant forms of fumarase C from E. coli have been made using PCR and recombinant DNA. The recombinant form of the protein included a histidine arm on the C-terminal facilitating purification. Based on earlier studies, two different carboxylic acid binding sites, labeled A- and B-, were observed in crystal structur…
The structures of magnesium chloride thin films grown on a Pd(111) surface have been studied using low-energy electron diffraction (LEED), temperature-programmed desorption, and Auger electron spectroscopy. At coverages slightly less than 1 monolayer a Pd(111)−(4×4)−MgCl 2 LEED pattern is observed by LEED that correla…
We provide a reciprocal relation linking the effective conductivity of a composite with highly conducting phase interfaces to that of a composite with the same phase geometry but with an electrical contactresistance at phase interfaces. A field relationship linking the electric field inside a composite with highly con…
Additions of urea were found to increase the yield of nickel sulfide formation from acidic solutions of thioacetamide. Two precipitation mechanisms were identified: hydrolysis and direct reaction between nickel and thioacetamide. Hydrolysis‐controlled precipitation is evident with low initial pH. The direct reaction i…
New possibilities for realization of narrow-band transmission filters are introduced. Guided-mode resonance effects in thin-film multilayer structures incorporating a grating layer are shown to yield high-efficiency bandpass transmission filters. Calculated transmission characteristics for such filters are presented a…
For long durability of magnetic media and head sliders, protective overcoats of hydrogenated amorphous carbon (a-C:H) are generally used. In this study, microtribological studies of hydrogenated amorphous carbon coatings deposited on a single-crystal silicon using three different deposition techniques—sputtering, ion…
Using first-principles calculations, we investigate the lattice dynamics of cubic and rhombohedral BaTiO3 and we discuss the origin of the structural instability of this ferroelectric material. First, we report results on the Born effective charges and the dielectric tensor and we emphasize the important reduction of…
A mechanism is proposed for the sonoluminescence (SL) arising from a single bubble maintained in levitation by an acoustic field. This proposal follows from a plasma diagnostic analysis which reveals that a single Ar bubble is characterized by a sparklike plasma (electron temperature and density: 20 000 K and 1025 m−3…
A new polymer system of semiconductor devices was studied in response to the multifunctional systems evolved. A variety of functional polymers have been developed in the manufacture of semiconductor and integrated circuit (IC) packaging devices by R&D of high-temperature polymers. With the increase in integration of e…
The results of magnetization (M), electrical resistivity (\ensuremath{\rho}), and heat-capacity (C) measurements for the alloys, ${\mathrm{Gd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Y}}_{\mathrm{x}}$Ni, are reported. The x-ray-diffraction patterns indicate that there is a change in the crystal structure from…
Fabric-evoked prickle is studied in a range of worsted spun single jersey knitted wool fabrics made from wools with different fiber diameter characteristics. Relative prickle sensation in these fabrics can be predicted from the density of coarse fiber ends per unit area of fabric, with the percentage of fiber ends gre…
This work deals with a mechanistic scheme for polymer oxidation, in which the unique source of radicals is the unimolecular decomposition of hydroperoxides. The corresponding kinetic scheme is resolved in the general case where no stationary state for radical concentration is postulated. The numerical results are in g…