Materials Literature
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The addition of electron donors to the vacant $A$ site of defect-perovskite structure tungsten trioxide causes a series of structural and chemical phase transitions; for instance, in the well-known case of the sodium tungsten bronzes $({\mathrm{Na}}_{x}{\mathrm{WO}}_{3})$. Here we calculate the effect of the addition…
The ability to control electronic properties of a material by externally applied voltage is at the heart of modern electronics. In many cases, it is the so-called electric field effect that allows one to vary the carrier concentration in a semiconductor device and, consequently, change an electric current through it.…
Carbon nanotubes have emerged as a possible new material for electronic applications. They show promising characteristics for transistors as well as for interconnects. Here we review their basic properties and focus on the status of nanotubes with respect to their application as interconnects and discuss the challenge…
We analyze a common feature of a nontrivial fractional flux periodicity in two-dimensional systems. We demonstrate that an addition of fractional flux can be absorbed into re-parameterization of quantum numbers. For an exact fractional periodicity, all the electronic states undergo the re-parameterization, whereas for…
From first principles calculations we determine the Coulomb interaction between two holes on oligo-acene and -thiophene molecules in a crystal, as a function of the oligomer length. The relaxation of the molecular geometry in the presence of holes is found to be small. In contrast, the electronic polarization of the m…
Using the mixture of zinc oxide and graphite powders as source materials, zinc oxide nanodisks with bulk quantity were fabricated by vapor-phase transport method. The nanodisks have perfect hexagonal shape with about 3μm in diagonal and 300nm in thickness. The growth is favored along six symmetric directions of ±[101¯…
The colloidal-synthesized ZnO nanorods with radius of 1.1±0.1nm (less than the bulk exciton Bohr radius, aB∼2.34nm) have been studied by optical methods combined with simple model calculations. The quantum confinement has been observed in these nanorods. The exciton binding energy is shown to be significantly enhanced…
White-light-emitting diodes are fabricated by using 375nm emitting InGaN chip with Sr3MgSi2O8:Eu2+ (blue and yellow) or Sr3MgSi2O8:Eu2+, Mn2+ (blue, yellow, and red). At a color temperature of 5892K, the color coordinates are x=0.32, y=0.33, and the color rendering index is 84%; at a color temperature of 4494K, the co…
We analyze nonlinear properties of microstructured materials with negative refraction, the so-called left-handed metamaterials. We demonstrate that the hysteresis-type dependence of the magnetic permeability on the field intensity allows changing the material properties from left- to right-handed and back. Using the f…
The signal transduction protein P(II) from the cyanobacterium Synechococcus elongatus strain PCC 7942 forms a complex with the key enzyme of arginine biosynthesis, N-acetyl-l-glutamate kinase (NAGK). Here we report the effect of complex formation on the catalytic properties of NAGK. Although pH and ion dependence are…
A modified version of the Moller-Plesset approach for obtaining the correlation energy associated to a Hartree-Fock ground state is proposed. The method is tested in a model of interacting fermions that allows for an exact solution. Using up to third order terms improved results are obtained, even more accurate in the…
We study the formation energies and repulsive interactions of monatomic steps on the TiN(001) surface, using density functional total-energy calculations. The calculated formation energy of [100] oriented steps agree well with recently reported experimental values; these steps are shown to have a rumpled structure, wi…
In living systems, the intramolecular cyclization of N-terminal glutamine residues is accomplished by glutaminyl cyclase enzymes (EC 2.3.2.5). While in mammals these enzymes are involved in the synthesis of hormonal and neurotransmitter peptides, the physiological role played by the corresponding plant enzymes still r…
We have studied the adsorption of a weak flexible polyelectrolyte, poly(acrylic acid), at an oppositely charged surface, the surface of water covered with a Langmuir film of dimethyldioctadecylammonium bromide. The surface charge density and the polymer ionization degree α were conveniently varied by varying respectiv…
Composition-spread La(1-x)SrxMnO3 thin films were prepared by pulsed laser deposition technique from LaMnO3 and SrMnO3 targets. The films were epitaxial with a continuous variation of the out-of-plane lattice parameter along the direction of composition gradient. Scanning Raman spectroscopy has been employed as a nond…
This study investigated the solubilization of valdecoxib in aqueous solution using ethanol as a cosolvent and sodium lauryl sulfate as a surfactant at (298.15, 303.15, and 308.15) K. The analysis of valdecoxib is carried out by UV spectral measurements at a λ max value of 201 nm. Preliminary investigations indicated b…
The effect of isocyanides as axial ligands on the formation and stability of verdoheme by oxidation has been examined. The reaction of [Fe(III)(OEPO)]2 with t-butyl isocyanide under dioxygen-free conditions results in the formation of (t-BuNC)2Fe(II)(OEPO*) with an electron paramagnetic resonance at g=2.009 with a pea…
This paper presents the crystallization behavior of calcium carbonate at the air/liquid interface of aqueous systems of carboxymethyl chitosan (CMCS) using the Kitano method. Although the synthesized CMCS (Mw approximately 100,000) with 1.57 degree of carboxymethyl substitution shows no surface activity, it controls t…
This paper reports on the preparation of polyester brushes at the surface of electrically conducting materials. A two-step strategy has been worked out that consists of the electropolymerization of an acrylate under a cathodic potential, such that the polyacrylate layer is chemisorbed at the surface. In a second step,…
We make here an effort to find commonality between the athermal constraint approach to glassiness due to Phillips and Thorpe, in which composition is the key variable, and the more conventional temperature-induced softening approaches to the glass transition at constant composition. A starting point for our discussion…