Materials Literature
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Electroconvection in an unusual nematic compound with strongly positive dielectric anisotropy and negative anisotropy of the conductivity is investigated. For homeotropic alignment, where one has a direct transition to rolls or squares depending on the frequency of the applied voltage, we present a quantitative theory…
GDP-D-mannose 4,6-dehydratase catalyzes the first step in the de novo synthesis of GDP-L-fucose, the activated form of L-fucose, which is a component of glycoconjugates in plants known to be important to the development and strength of stem tissues. We have determined the three-dimensional structure of the MUR1 dehydr…
Thermodynamic basicities of several new nonplanar water soluble tetraaryltetracyclohexano- (Ar(4)TCHP) and tetraaryltetrabenzoporphyrins (Ar(4)TBP) have been measured and correlated with their structural parameters. While the degrees of nonplanarity in these porphyrins are similar, Ar(4)TCHPs exhibit significantly hig…
The first results of a medium-scale structural genomics program clearly demonstrate the value of using a medium-throughput crystallization approach based on a two-step procedure: a large screening step employing robotics, followed by manual or automated optimization of the crystallization conditions. The structural ge…
Spray pyrolysis, an aerosol decomposition technique, was first used to synthesize ZnS:Mn 2+ particles, and their optical properties were characterized. The effects of process parameters on the properties of ZnS:Mn 2+ particles were systematically investigated for Mn 2+ doping concentrations of 0−8 at. %. The results s…
Abstract The reaction of diallyl amine with 1,3‐propane sultone led to the synthesis of the zwitterionic monomer 3‐( N , N ‐diallylammonio)propanesulfonate. The sulfobetaine was cyclopolymerized in water in the presence of sodium chloride with t ‐butylhydroperoxide as an initiator to afford a polysulfobetaine (PSB) in…
We report the infrared (IR) response of bulk samples of multiwalled boron nitride nanotubes, produced by a substitution reaction from single walled carbon nanotubes, which is dominated by two characteristic BN-vibrations at 800 and 1372 cm-1.
Trichloroethylene (TCE) decomposition over a MnOx/ gamma-Al2O3 catalyst in a fixed-bed reactor was conducted in this study. The MnOx/gamma-Al2O3 powders were prepared by the incipient wetness impregnation method with aqueous solution of manganese nitrate. The catalysts were characterized by DTA-TGA, XRD, porosity anal…
We use infrared spectroscopy and Raman scattering to show that molecular vibrations considerably contribute to the linear electro-optic effect in the highly nonlinear optical organic crystal 4-N,N-dimethylamino-${4}^{\ensuremath{'}}\ensuremath{-}{\mathrm{N}}^{\ensuremath{'}}$-methyl stilbazolium tosylate (DAST). In ad…
Second harmonic generation magneto-optic Kerr effect (SHMOKE) experiments, sensitive to buried interfaces, were performed on a polycrystalline NiFe/FeMn bilayer in which areas with different exchange bias fields were prepared using 5 KeV He ion irradiation. Both reversible and irreversible uncompensated spins are foun…
Present knowledge of the function of materials is largely based on studies (experimental and theoretical) that are performed at low temperatures and ultra-low pressures. However, the majority of everyday applications, like e.g. catalysis, operate at atmospheric pressures and temperatures at or higher than 300 K. Here…
We study the energy structure of two-dimensional holes in p-type single Al_{1-x}Ga_{x}As/GaAs heterojunctions under a perpendicular magnetic field. Photoluminescence measurments with low densities of excitation power reveal rich spectra containing both free and bound-carrier transitions. The experimental results are c…
Accuracy in complex dielectric permittivity calculations in binary dielectric mixtures in two-dimensions are reported by taking into account the shape of the inclusion phase. The dielectric permittivity of the mixtures were calculated using the finite element, and the permittivities were estimated by two different pro…
We investigate particle rearrangements in colloidal glasses subjected to oscillatory shear strain by the technique of light scattering (LS) echo. LS echo directly follows the motion of the particles through peaks (echoes) in the intensity autocorrelation function; the height of the peak measures the reversible motion…
We present models of surfaces of crystals in an environment where molecular beam epitaxy (MBE) and related methods of crystal growth like atomic layer epitaxy (ALE) can be performed. Besides detailed models of reconstructed (001) surfaces of II-VI semiconductors like CdTe and ZnSe, we study generic models to adress fu…
Plenty of saddles on a multidimensional potential energy surface(PES) of two-dimensional microclusters, where atoms are interacting via Morse potential, are numerically located. The reaction paths emanating from the two types of the local minima, which represent the compact and the non-compact shape of Morse clusters,…
In this paper, we report on the sharp peak observed in the third harmonic voltage response generated by a bias sinusoidal current applied to several strips patterned in a YBa2Cu3O7-d thin film and in two La1-xSrxCuO4 thin films, when the temperature is close to the normal-superconductor transition. The lambda-shaped t…
A two-dimensional binary composite system composed of ellipse inclusions and a host medium is considered. Dielectric permittivity of the system is calculated as a function of orientation angle, the volume fraction of the inclusions and their excentricity using the finite element method. It was observed that both the o…
Abstract The thermomechanical properties, morphology, and gas permeability of hybrids prepared with three types of organoclays were compared in detail. Hexadecylamine–montmorillonite (C 16 –MMT), dodecyltrimethyl ammonium bromide–montmorillonite (DTA‐MMT), and Cloisite 25A were used as organoclays in the preparation o…
The dynamic behaviour of the ammonium ion in synthetic ND 4/NH4-phlogopite has been studied as a function of temperature by infrared spectroscopy, from room temperature to 20 K. Ammonium occupies the interlayer site in phlogopite. Orientational order-disorder of NH 4 + is a well-established phenomenon in ammonium chlo…