Materials Literature
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The mechanism of the partial oxidation of CH 4 was studied by a transient response analysis of a broadened pulse combined with either a step change or a sharp isotopic pulse. Over the unreduced NiO/SiO 2 catalyst, the reaction between CH 4 and O 2 occurs via the Eley−Rideal mechanism, CH 4 in the gas phase (or weakly…
We present a theoretical analysis of the influence of ambient pressure on single-bubble sonoluminescence (SBSL). By combining simulations of gas dynamics, mass diffusion theory, and stability analysis we find a narrow region of the parameter space where stable SBSL is possible. In particular, the theory predicts a 200…
Abstract A method for qualitative and quantitative analysis of scanning electron microscope (SEM) images forthe determination of sharpness is presented in this paper. Described is a procedure for qualitative analysis based on a software program called SEM Monitor that can be applied to research or industrial SEMs for…
The investigation in the cyclic behaviour of ultra-fine grained copper produced by severe plastic deformation was performed in fully reversed tension/compression under constant plastic strain amplitudes. It is shown that UFG copper possesses unusual fatigue properties such as a high saturation stress and a clearly pro…
A special class of nano-porous inorganic dielectrics, the silicon dioxide aerogels, with porosities >70% were prepared using single and two-step sol-gel processing and a supercritical drying method. Samples, pretreated at temperatures /spl les/800/spl deg/C for several hours, and with chemical surface modification by…
The structure of the catalytically active, reduced, form of the enzyme hydroxymethylbilane synthase (HMBS, Lys59Gln mutant) has been studied by Laue diffraction as the substrate, porphobilinogen (PBG), was fed to an immobilised crystal in a flow cell. Laue data at short time-scale time points (i.e. 1, 2, 4 and 8 min)…
We present results of computer simulations of polymer brushes (layers of polymer chains attached at one end onto an impermeable planar surface) under shear deformation at constant shear rate. As the first stage of calculations the behavior of a single brush was studied. The monomer density profile, the distribution of…
Evidence of a transformation from tetragonal to rhombohedral phases in a 80/20 mixture of lead ziconate titanate (PZT) (53/47) and lead magnesium niobate-lead titanate (PMN-PT) (65/35) was observed by x-ray diffraction, microstructural analysis, dielectric spectroscopy, and electrically-induced strain measurements. An…
We have measured the electrical resistivity and the Hall effect in D03-type (Fe1−xVx)3Al alloys with 0≤x≤0.38. When substituted by V, the electrical resistivity increases rapidly at low temperatures and shows an anomalous temperature dependence: an occurrence of a resistance maximum at or near the Curie point TC and a…
Synthesis of a monosubstituted ferrocene-based chiral Schiff’s base derivative with unusual mesomorphic behavior is reported namely the first metallomesogen which exhibits TGBA and blue phases apart from SC*, SA and N* phase transformations.
A novel and direct synthesis of hydroperoxy compounds from various types of conjugated olefins was established via cobalt(II) porphyrin-catalyzed hydroperoxygenation. The reaction of α,β,γ,δ-unsaturated carbonyl compounds, acrylic esters, α-substituted acrylic esters and styrene derivatives with molecular oxygen and t…
The reaction of p-bromo(triisopropyloxysilyl)benzene 2 with magnesium led to stable THF solutions of the corresponding Grignard reagent. The reaction of this latter with PCl3 or PhPCl2 allowed the preparation of phosphines 4 and 5 respectively. LiAlH4 reduction of 4 afforded phosphine 6. Compounds 4 and 6 have been tr…
The oxidation of 1-(substituted phenylazo)-2-hydroxynaphthalene-6-sulfonate dyes by oxoiron(IV) tetra(2,6-dichloro-3-sulfonatophenyl)porphyrin (OFeIVTDCSPP) in aqueous solution is first-order in the concentration of the dye and of the oxoiron(IV) species over the pH range 6.93–12.68. The pH dependence of the second-or…
Fluoroalcohols [1,1,1,3,3,3-hexafluoropropan-2-ol (HFP), 2,2,2-trifluoroethanol (TFE) and 2-fluoroethanol (FE)], acting as Lewis acids, stabilize the π-conjugated, colored merocyanine forms of spiropyran and spirooxazine photochromic compounds as metal ions do.
Ab initio static electronic dipole hyperpolarizabilities, β(0), were computed for 1-(1‘,X‘-dicarba-closo-dodecaborane-1‘-yl)-closo-dodecaborane dianion (X = 2, 7, 12). These dianions have relatively large β(0) values (3.6 × 10-30 cm5 esu-1) comparable to those for 4-nitroaniline in spite of their short transition wave…
The interaction between haematite powder and formic acid has been studied at atmospheric pressure by FTIR and under high-vacuum conditions by X-ray photoelectron spectroscopy (XPS) and mass spectroscopy (MS). At room temperature formic acid is adsorbed mainly molecularly whereas dissociative chemisorption is prevalent…
A series of metalloporphyrin-containing cyclic hosts has been prepared, which are electronically and geometrically programmed to recognize guests in a particular configuration. Electronic control is achieved by substituting the C–H meso positions with carbonyl groups, while geometric control is possible in the choice…
119 Sn solid state nuclear magnetic resonance, 119Sn Mössbauer, Fourier transform Raman and variable temperature single crystal UV–VIS absorption, emission and excitation spectra of some archetypal microporous layered tin sulfides, denoted (Et4N)2Sn3S7 (TEA-SnS-1), (C6H12N2H)2Sn3S7 (DABCOH-SnS-1), (NH4)0.5(Et4N)1 .5Sn…
The crystal structure of the title compound was determined at 250 K in space group I 4 bar 2m, a = 20.661(5) Å , c = 6.764(7) Å , Z = 8. The individual dithiadiazole rings form two sets of contrarotatory 4-member pinwheels clustered around a 4-fold rotation-inversion axis located halfway along the unit cell edges, des…
This paper presents an experimental study on the manufacture of low-density fine-cell high density polyethylene (HDPE) foams in extrusion using CO 2 as a blowing agent. The strategies adopted to produce low-density, fine-cell HDPE foams were to generate a large number of cells by a rapid pressure drop, to suppress cel…