Materials Literature
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The review surveys data on the known structures of polyoxometalates. The changes in this field which have occurred in the last ten years are traced. Heteropolyacids are considered in detail as a special case of polyoxometalates: their composition and structure, methods of synthesis, stability, and acidity. The bibliog…
First-principles calculations based on density functional theory (DFT) and the pseudopotential method have been used to study the stoichiometric and reduced SnO2 (110) surface. The ionic relaxations are found to be moderate for both the stoichiometric and reduced surfaces, and are very similar to those found in recent…
In a recent PRL, Gonze et al claim that the density functional theory in Hohenberg-Kohn formulation is not valid for crystalline solids in a homogenious electric field. They introduce another theory, density-and-polarization functional theory, which has to substitute the DFT in the calculations of the long-wave dielec…
The low-temperature specific heat for non-magnetic Mg 42 Y 8 Zn 50 quasicrystal has been investigated to get information on the electronic structure. The electronic specific heat coefficient gamma is estimated to be 0.63 mJ mol -1 K -2 , which is about 70% of the value expected from the free-electron model. This small…
A method is presented to calculate ab initio exchange constants and spin-wave excitations of multi-sublattice magnetic structures on the basis of total-energy calculations of incommensurate magnetic structures. Here the exchange energies, dispersion curves and Curie temperature for magnetite (Fe 3 O 4 ) are obtained a…
Far-infrared transmittance and reflectance of PbTiO 3 , PbZr 0.53 Ti 0.47 O 3 and PbZr 0.75 Ti 0.25 O 3 thin films deposited by a sol-gel technique on sapphire substrates were measured between room temperature and 650 degrees C. The spectra were fitted with a classical oscillator model to calculate the dielectric resp…
Persistent spectra hole burning is observed at room temperature in the excitation spectrum for the 7F0→5D0 transition of the Sm2+ ions that are doped in aluminosilicate glass. Glass having the composition of Sm2+-doped Al2O3⋅9SiO2 has been prepared by the sol-gel processing of metal alkoxides and the reaction with H2…
A nanometer-scale recording technique has been demonstrated on an amorphous GeSb2Te4 film with an atomic force microscope (AFM). Data are recorded by locally changing the electrical property of the film with a conductive AFM probe. The conductance of the film is able to be increased more than one hundred times by appl…
A high quantum efficiency for a porous silicon light emitting diode (LED) is demonstrated under pulsed operation. The LED is fabricated from a p+nn+ structure by anodic/hydrofluoric etching followed by deposition of a transparent gold contact. The LED shows a rectifying behavior and emits orange-red light under forwar…
We report electrical impedance measurements of polymer light-emitting diodes employing the soluble, conjugated polymer poly[2-methoxy, 5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) as the light-emitting layer. The diode structures were metal-polymer-metal structures utilizing thin gold as the transparent, po…
Doxorubicin entrapped within conventional liposomes (200 nm in diameter; lip-Dox) has major toxic effects on liver macrophages of the rat for a considerable period of time following i.v. administration, with respect to both specific phagocytic capacity and cell numbers. At different time-points after injection of lip-…
In the vicinity of the phase-matching angle of second-order nonlinear optical crystals, the fundamental light wave experiences an intensity-dependent phase shift which is connected with the effective attenuation due to second-harmonic generation. It is demonstrated that in the limit of weak pump depletion, the Kramers…
Variations in the band structures of the two-dimensional C60-polymers are studied, when pi-conjugation conditions are changed. We investigate the rectangular and triangular polymers, in order to discuss metal-insulator transitions, using a semiempirical model with the Su-Schrieffer-Heeger type electron-phonon interact…
An efficient method has been developed for the catalytic oxidation of pollutants that are not easily degraded. The products of the hydrogen peroxide (H(2)O(2)) oxidation of 2,4,6,-trichlorophenol (TCP) catalyzed by the iron complex 2,9,16,23-tetrasulfophthalocyanine (FePcS) were observed to be chloromaleic, chlorofuma…
A metastable phase of NbN with superconducting Tc=16.4 K was reported recently by Treece and collaborators. The reported structure of the thin film sample deviates from the rocksalt (B1) NbN structure with 25% ordered vacancies on each sublattice (space group Pm3m) and a lattice constant of 4.442 Angstroms. Using full…
Abstract The application of a new macrokinetic approach to polymer crystallization is applied in this work to a new thermoplastic polyimide (New TPI) recently developed as a matrix of advanced polymer matrix composites. The slow crystallization kinetics presented by New TPI in the entire range between the glass‐transi…
Tryptophan fluorescence spectroscopy has been used to investigate the effects of sugars and coupling cations (H+, Na+, or Li+) on the conformational properties of purified melibiose permease after reconstitution in liposomes. Melibiose permease emission fluorescence is selectively enhanced by sugars, which serve as su…
Abstract Structure–property relationships of segmented block copolyetheramides based on nylon 6 and polyoxypropylene (POP) were investigated as a function of the compositions and block lengths of the hard and soft segments by using differential scanning calorimetry, dynamic mechanical analysis, FT‐IR spectroscopy, wid…
Abstract The microstructure of polyethylene (PE)/PE composites, consisting of the high‐density PE (HDPE) matrix and ultrahigh molecular‐weight PE (UHMWPE) fibers, was investigated. Single‐fiber composites were prepared and analyzed in a hot‐stage crystallization unit attached to a polarizing microscope, aiming to find…
We discuss a {\em family} of planar (two-dimensional) systems with the following phase strucure: a Fermi liquid, which goes by a second order transition (with non classical exponent even in mean-field) to an intermediate, inhomogeneous state (with nonstandard ordering momentum) , which in turn goes by a first order tr…