Materials Literature
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The nifV gene product (NifV) from Azotobacter vinelandii was recombinantly expressed at high levels in Escherichia coli and purified. NifV is a homodimer that catalyzes the condensation of acetyl coenzyme A (acetyl-CoA) and alpha-ketoglutarate. Although alpha-ketoglutarate supports the highest level of activity, NifV…
Single crystals of ${\mathrm{La}}_{0.85}{\mathrm{Sr}}_{0.15}{\mathrm{MnO}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ were prepared with various oxygen vacancies from \ensuremath{\delta}=0 to \ensuremath{\delta}=0.055. The $b$ and $c$ lattice parameters were found to increase with \ensuremath{\delta} wher…
The dielectric loss of cyclo-octanol has been investigated in a very broad frequency window of more than 17 decades. The relaxational response was traced in the plastic and the supercooled plastic phase, which are governed by the same relaxational dynamics. Experimental evidence is provided for two additional relaxati…
The double-layer structure of Langmuir−Blodgett (LB) multilayer assemblies formed by a thermotropic polyacrylate with 2-hydroxyethyl and [[[[(2-methylbutyl)oxy]phenyl]azo]phenoxy]hexyl side groups is modified by annealing and on ultraviolet (UV) irradiation. Both procedures cause order−disorder transitions. The intera…
We have analyzed the influence of different amounts w bc of two diblock copolymers, poly(styrene- b -methyl methacrylate) (sm blend series) and poly(cyclohexyl methacrylate- b -methyl methacrylate) (cm blend series), on the morphological and rheological characteristics of a blend containing w = 7.5 wt % polystyrene in…
Palladium-catalyzed polycondensation between diiodoferrocenes (1,1‘-diiodoferrocene and 1,6-diiodo-1‘,6‘-biferrocene) and diethynyl aromatic compounds HC⋮C Ar C⋮CH (e.g., 2,5-diethynylpyridine and 2,5-diethynyl-3-hexylthiophene) gives poly(aryleneethynylene) (PAE) type polymers containing the ferrocene unit in the π-c…
Stereoregular polymerization of ( o -ethoxyphenyl)acetylenes (OEPA) was performed using a [Rh(norbornadiene)Cl] 2 catalyst in the presence of triethylamine to give poly(( o -ethoxyphenyl)acetylene) (POEPA) bearing a cis-transoid form under mild conditions. The polymer underwent isomerization from the predominant cis f…
Abstract For mixed-layer clay fractions from the North Sea and Denmark, X-ray diffractograms have been recorded for specimens saturated with Mg, Ca, Na and NH 4 , both airdry and intercalated with ethylene glycol, and the patterns have been computer-simulated with a multicomponent program. The mixed-layer fractions co…
Asymmetric ferroelectricity and conduction of anomalous leakage current were observed in heteroepitaxial BaTiO 3 thin films grown by rf magnetron sputtering at 600° C on three different electrode/substrate combinations: SrRuO 3 /SrTiO 3 , Pt/MgO and Nb doped SrTiO 3 . The voltage shift of hysteresis loops of the capac…
Fourier transform Raman spectroscopy of a thiophene solution shows a reduction of aromaticity of the thiophene ring by the interaction with a solvated Lewis acid, which lowers the oxidation potential of the monomer. Low-potential electrochemical deposition of polythiophene was carried out in the presence of a Lewis ac…
Three one-dimensional molybdenum oxide/2,2‘-bipyridine species have been prepared by hydrothermal methods and structurally characterized. The reaction of MoO 3, 2,2‘-bipyridine, and H 2 O in the mole ratio 1:0.68:680 at 160 °C for 120 h in a 23 mL Teflon-lined Parr acid digestion bomb produces colorless rods of [MoO 3…
We have examined the Raman spectra of violet and infrared emitting Ge+-implanted SiO2 films with special emphasis upon annealing temperature (AT) dependence of Raman scattering. We found that the complete spectrum mainly consists of three bands at 220–280, 300, and 430 cm−1, corresponding to scattering of Ge-related c…
Bubble levitation in an acoustic standing wave is re-examined here for the case of single-bubble sonoluminescence. The equilibrium position of the bubble is calculated by equating the average Bjerknes force with the average buoyancy force. The predicted values, as a function of pressure amplitude, are compared with ex…
Ferroelectric properties and the effect of Li + and Mg 2+ dopants in II–VI semiconductor ZnO were studied. The ferroelectric D – E loops were observed in Zn 1- x (Li 0.02 ·Mg x -0.02 )O, as well as in Zn 1- x Li x O. The transition temperature ( T c ) increases in proportion to the concentration of Mg 2+ ions, while i…
The formation mechanism of the hexagonal, MCM-41, and the lamellar, MCM-50, mesoporous materials, prepared at room temperature with the surfactant cetyltrimethylammonium chloride (CTAC) and tetraethylorthosilicon (TEOS), was studied by in situ EPR spectroscopy using the spin probe 4-( N, N -dimethyl- N -hexadecyl)ammo…
The pressure-temperature phase diagram of tetrathiafulvalene-p-chloranil, prototype for the neutral-to-ionic transition, is determined by neutron diffraction and nuclear quadrupole resonance and discussed in relation to thermally induced charge-transfer (CT) excitations. The respective role of ionicity and dimerizatio…
Simple cobalt porphine, adsorbed on graphite electrodes, catalyzes the direct reduction of O2 to H2O, while most other monomeric cobalt porphyrins do not. The surprising behavior of cobalt porphine suggests possible new strategies for the design of electrocatalysts for the reduction of O2 to H2O using structurally sim…
We report the effect of mixing three rare-earth (RE) elements in the RE site on the superconducting properties of melt-processed , in which RE elements are selected from the group of Nd, Sm, Eu and Gd. The heat treatment profiles for melt processing were determined according to the peritectic decomposition temperature…
The electronic and ionic conduction across grain‐boundary (GB) space‐charge depletion layers in acceptor‐doped SrTiO 3 ceramics have been investigated by admittance analysis in the time domain. The dependence on the acceptor concentration, the oxygen partial pressure during equilibration, and the temperature dependenc…
Scanning force microscopy (SFM) has been used to perform nanoscale studies of domain structures and switching behaviour of (PZT) thin films. An SFM piezoresponse mode, based on the detection of the piezoelectric vibration of a ferroelectric sample, was shown to be suitable for high resolution imaging of ferroelectric…