Materials Literature
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The importance of van der Waals contact between Glu 35 and Trp 109 to the active-site structure and the catalytic properties of human lysozyme (HL) has been investigated by site-directed mutagenesis. The X-ray analysis of mutant HLs revealed that both the replacement of Glu 35 by Asp or Ala, and the replacement of Trp…
The new high-pressure synthesis route to obtain mixed compounds along the perovskite join with non-transition (metastable phase) and transition metal B cations is reported. The structure of the recovered phases is discussed within the Pm3m space group. TO-LO splittings and dielectric constant, inferred from the infrar…
The structural parameters that predominantly influence dye diffusion behaviour in heat–set polyester fibres have been identified. Dye diffusion has been shown to depend on two factors: the volume of the accessible region (amorphous region) and the tortuosity of the dye diffusion path. The accessible region can be repr…
The new Ag 2 Ti 2 P 2 S 11 quaternary phosphosulfide disilver dititanium undecathiodiphosphate is obtained by heating the elements at ca 850 K in an evacuated silica tube. It crystallizes in orthorhombic symmetry, Pnma space group, with a = 8.5222 (11), b = 6.8359 (10), c = 24.142 (4) Å, V = 1406.4 (4) Å 3 and Z = 4 a…
In this work we have studied the interfacial reactions between chromium and an Al2O3(11-02) surface with X-ray photoelectron spectroscopy and Auger electron spectroscopy. The results reveal that, at room temperature, the interfacial reactions are dominated by the interaction of Cr atoms with the oxygen anions on the A…
The results of dilatometric and dielectric researches of Ba(Ti0.70Sn0.30)O3-ceraniic are presented. A destructive influence of Sn-ions on building of ferroelectric domains in the temperature of para-ferroelectric phase transition has been revealed. It is connected with the freezing of polar regions, started up in para…
(Perchlorato)cobalt(III) porphyrins bind acetylene reversibly in anhydrous CH 2 Cl 2 . The 1 H NMR and UV−vis spectra of the acetylene adduct at room temperature are characteristic of a Co II N-substituted porphyrin. The ESR spectra of the acetylene adduct in CH 2 Cl 2 at 4.2 and 77 K showed signals due to a π-cation…
The electrical resistivity of ${\mathrm{R}}_{2}$${\mathrm{Fe}}_{14}$B (R=lanthanide series) polycrystalline samples was measured over the temperature range of 4--700 K. Even though the overall behavior of the resistivity in ${\mathrm{R}}_{2}$${\mathrm{Fe}}_{14}$B is determined mainly by Fe atoms, interesting features…
Recently, porous silicon has been extensively studied due to its luminescence properties and some interesting features for micromechanical technology, characteristics that have led to a wide range of applications, from electro-optical devices to IR radiation detectors and gas sensors. It is therefore very important to…
Hydrothermal investigations of the high silica region of the Na 2 O–Nd 2 O 3 –SiO 2 system, carried out in the search for new fast-ion conductors (FIC's), yielded the compound Na 3 NdSi 6 O 15 ·2H 2 O (sodium neodymium silicate). Single-crystal X-ray methods provided lattice constants of a = 7.385 (2), b = 30.831 (7)…
The experimental results of electrical conductivity temperature dependence and photoconductivity spectra studies of Sn2P2S6 ferroelectrics are reported. It is shown that dark electrical conductivity have two states—high-resistive (background) and low-resistive (induced by preliminary light irradiation). The results ar…
A modified kinetic Monte Carlo computer simulation has been developed and applied to the investigation of fiber (out-of-plane) texture formation in polycrystalline thin films grown in the absence of high-energy bombarding particles. Unlike high-energy deposition, in which texture formation appears to result from a com…
Crack/particle interactions in alumina/silicon carbide nanocomposites have been investigated by scanning electron microscopy and transmission electron microscopy, with cracks induced by Vickers microindentation. Intergranular cracks are frequently deflected into grains by SiC particles on grain boundaries inclined to…
An explanation is given for the narrow peak in the temperature dependence of the component α 32 of the magnetoelectric effect tensor near the transition at T = T c to the m ′ m 2′ phase observed in the boracites. A phenomenological approach is used which is based on the symmetry of the cubic phase of the crystals. The…
The self-diffusion of a particle on a flexible surface, such as a fluid bilayer membrane or a macroscopic interface, is analyzed theoretically in order to relate the macroscopic diffusion coefficient DM, describing displacements in a laboratory-fixed plane, to the intrinsic surface diffusion coefficient DS and to the…
Epoxidation of olefins by dioxygen in combination with aldehyde as reducing agent can be carried out at room temperature, in the absence of metal catalysts, using perfluorocarbons as inert reaction media. These non-toxic, non ozone-depleting fluids are good alternatives to the chlorinated solvents normally used.
Experimental data about the dependence of the Auger signal from crystalline samples on the primary beam direction are presented and discussed. It is shown that, for Auger electrons and elastically and inelastically backscattered electrons, maxima of the signal in its dependence on the polar and azimuth angles of the p…
The proteins encoded by the fructose-inducible lev operon of Bacillus subtilis are components of a phosphotransferase system. They transport fructose by a mechanism which couples sugar uptake and phosphoenolpyruvate-dependent sugar phosphorylation. The complex transport system consists of two integral membrane protein…
The synthesis, characterization, thermal, and dielectric properties of three different zwitterionic methacrylates of the sulfobetaine type are presented. Diethylamine-ethyl-, 2-(diethylaminoethoxy)-ethyl-, and 2-(2-diethylaminoethoxy) ethoxy-ethyl-methacrylates were made to react with butanosultone to prepare monomers…
Because the dipole moment of its zwitterionic side group is very high (μ∼23 D), poly[3-(N,N-diethyl-N-(5-methacryloyoxy-3-oxopentyl)-ammonio) propanesulfonate] affords a unique polar host matrix possessing a strong solvation power towards a variety of polar or ionic guest species. Water, glycerol, liquid ethylammonium…