Materials Literature
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The grain size dependence of the “giant dielectric effect” in CaCu3Ti4O12 ceramics (arising from a semiconducting grain/insulating grain boundary microstructure) has been revealed by impedance spectroscopy of ceramics sintered for 3 h (see Figure, left) and 24 h (see Figure, right); a rise in permittivity from 9000 to…
Polymers can be theoretically and computationally described by models pertaining to different length scales and corresponding time scales. These models have traditionally been used independently of each other. Recently, considerable progress has been made in systematically linking models of different scales. This Revi…
Inorganic nanostructures that interface with biological systems have recently attracted widespread interest in biology and medicine. Nanoparticles are thought to have potential as novel intravascular probes for both diagnostic (e.g., imaging) and therapeutic purposes (e.g., drug delivery). Critical issues for successf…
We study effects of an oxygen vacancy on the electronic state of the CuO 2 plane in the normal state, on the basis of the d – p model. We calculate the local density of states at copper sites and oxygen sites around the p x -oxygen vacancy, at T = T c . The spatial distribution has a shape which oscillates along the d…
Determination of the Switching Response in Reflective Twisted Nematic Liquid Crystal Displays, Bougrioua, Fatiha, Oepts, Wouter, Vleeschouwer, Herbert De, Alexander, Els, Neyts, Kristiaan, Pauwels, Herman
The notion of random close packing (RCP) has been utilized as a guiding concept for analysis of randomly packed structure of hard spheres. The concept has been proved to be useful in many practical applications in which some elements are packed in a limited space. Carbon blacks dispersed in a solvent and colloidal sus…
Tin-doped indium oxide (ITO) thin films were deposited at room temperature by a dual-oxygen-ion-beam-assisted evaporator system and the effects of doped tin concentrations in the films on the electrical properties of the ITO films were investigated. Doped tin atoms in amorphous ITO films caused extra scattering and st…
Amorphous hydrogenated silicon carbide (a-SiC:H) films were deposited from a mixture of silane and methane gases using the plasma-enhanced chemical vapor deposition (PECVD) process. The properties of the film, following ammonia plasma treatment, are reported. A lower silane flow rate reduces the refractive index, but…
Optical properties of single-walled boron nitride nanotubes have been studied theoretically. The dielectric functions calculated from the gradient approximation and the random-phase approximation are consistent with each other. The imaginary and the real parts of the dielectric function, respectively, exihibit the spe…
We have studied an oxidation effect of multiwalled carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition (CVD) using ultraviolet photoelectron spectroscopy (UPS) and transmission electron microscopy (TEM). With an increasing oxygen exposure, the carbon 2 p -π states at ∼3 eV below the Fermi level in the…
The analysis of the different amino acid sequences deduced from the complete genome sequence of the gram-positive bacterium Staphylococcus aureus suggested the presence of two eukaryotic-protein-like low-molecular-mass phosphotyrosine protein phosphatases, which are usually found in gram-negative bacteria. To check th…
Polycrystalline ZnO films both exhibiting strong ultraviolet (UV) photoluminescence (PL) and having smooth surfaces applicable to electronic devices have been obtained by rf-sputter deposition and subsequent heat treatment. The peak of UV PL was located at 3.05 eV and exhibited a linewidth as narrow as 70 meV, along w…
Anisotropic optical spectra coupled with antiferromagnetic spin ordering (SO) and orbital ordering (OO) have been investigated for single crystals of LaVO_{3} and YVO_{3}. The orbital-dependent Mott-Hubbard gap transitions are observed around 2 eV. The transitions composed of the two peaks show distinct anisotropy and…
A multiscale scheme combining molecular dynamics (MD) and microscopic phase-field theory is proposed to study the structural phase transformations in solids with inhomogeneous strain field. The approach calculates strain response based on MD and atomic diffusion based on the phase field theory. Simulations with the ne…
We study phase diagrams of the Hubbard model on anisotropic triangular lattices, which also represents a model for $\kappa$-type BEDT-TTF compounds. In contrast with mean-field predictions, path-integral renormalization group calculations show a universal presence of nonmagnetic insulator sandwitched by antiferromagne…
The ability of an arginine residue to function as the active site acid catalyst in the fumarate reductase family of enzymes is now well-established. Recently, a dual role for the arginine during fumarate reduction has been proposed [Mowat, C. G., Moysey, R., Miles, C. S., Leys, D., Doherty, M. K., Taylor, P., Walkinsh…
We report an improvement in oxidation resistance of single-walled carbon nanotubes (SWNTs) produced by arc discharge in a bowl-like cathode. The Raman spectrum of the new arc-discharge SWNTs shows a significant enhancement in the G/D (∼1590:∼1350 cm -1 ) ratio, suggesting that cleaner and less defective SWNTs are gene…
Two one-dimensional gallium fluorodiphosphates Ga(P 2 O 7 )F·H 3 N(CH 2 ) 3 NH 3 ·3H 2 O, 1, and Ga(P 2 O 7 )F·H 3 N(CH 2 ) 3 NH 3 ·H 2 O, 2, have been synthesized under mild conditions (<100 °C) from aqueous mixtures of Ga(NO 3 ) 3 ·6H 2 O, P 2 O 5, 1,3-diaminopropane, and HF. Their structures consist of anionic chai…
The photophysical and photochromic properties of 2,2-diphenyl-2H-naphtho[1,2-b]pyran and substituted derivatives were investigated by steady state and time-resolved optical absorption and emission spectroscopy in solution at room temperature and in a frozen matrix at 77 K. Fluorescence quantum yields, fluorescence lif…
Simple methods for preparing boron carbide nanowires have been investigated. The methods involve thermal evaporation of C/B/B 2 O 3 powder precursors in an argon atmosphere with or without metal catalysts. High-purity nanowires (50−200 nm) were obtained by employing a precursor that has C:B:B 2 O 3 molar ratios of 1:2…