Materials Literature
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We investigate electronic transport properties of single-walled carbon nanotubes (SWNT's) under hydrostatic pressure, using first-principles quantum transport calculations aided by molecular-dynamics simulation and continuum mechanics analysis. We demonstrate a pressure-induced metal-to-semiconductor transition in arm…
The crystal structure of NAD(+)-dependent alcohol dehydrogenase from Bacillus stearothermophilus strain LLD-R (htADH) was determined using X-ray diffraction data at a resolution of 2.35 A. The structure of homotetrameric htADH is highly homologous to those of bacterial and archaeal homotetrameric alcohol dehydrogenase…
Abstract This work investigated the ion exchange of ammonia on clinoptilolite obtained from mineral deposits located in San Luis Potosi and Sonora, Mexico. Experimental ion exchange isotherm data were obtained in a batch adsorber. The effects of temperature and solution pH on the ion exchange capacity were studied and…
High-purity gold films were deposited onto metal, ceramic, and polymer substrates by the H 2 -assisted reduction of dimethyl(acetylacetonate)gold(III) in supercritical CO 2 at temperatures between 60 and 125 °C. At 125 °C and 150 bar, Au deposition proceeded readily on all surfaces studied, including SiO 2 and TiN fil…
A novel class of thermosensitive and biodegradable polymers, poly(N-(2-hydroxypropyl) methacrylamide mono/di lactate) (poly(HPMAm-mono/di lactate)), was synthesized. The cloud points (CP) of poly(HPMAm-monolactate) and poly(HPMAm-dilactate) in water were 65 and 13 degrees C, respectively. The lower CP for poly(HPMAm-d…
The persistent proximity of insulating and metallic phases, a puzzling characteristic of manganites, is argued to arise from the self-organization of the twofold degenerate e(g) orbitals of Mn into localized Jahn-Teller (JT) polaronic levels and broad band states due to the large electron-JT phonon coupling present in…
Exquisite nanoscale architectures are exhibited by siliceous diatom shells (see picture of the cell wall of Stephanopyxis turris). A hierarchy of hexagonal silica structures is a major motif. Long-chain polyamines are a constituent of biosilica and had been proposed to be involved in pattern formation. In vitro studie…
Dressed up to the nines: A nonanuclear FeII complex exhibiting rare μ4:η1 azido bridges that induce ferromagnetic exchange interactions possesses a core with a very large ground-state spin (probably S=14, see picture). The combination of a large S value and the magnetic anisotropy of iron(II) centers endows this uniqu…
In alloys cluster expansions (CE) are increasingly used to combine first-principles electronic-structure and Monte Carlo methods to predict thermodynamic properties. As a basis-set expansion in terms of lattice geometrical clusters and effective cluster interactions, the CE is exact if infinite, but is tractable only…
Using angle resolved photoemission we have investigated annealing-induced changes in Ga(1-x)Mn(x)As with x = 0.05. We find that the position of the Fermi energy is a function of annealing time and temperature. It is also established that the Curie temperature is strongly correlated to the separation between the Fermi…
We report on the nonlinear optical dynamical properties of excitonic complexes in CdTe modulation-doped quantum wells, due to many-body interactions among excitons, trions and electrons. These were studied by time and spectrally resolved pump-probe experiments. The results reveal that the nonlinearities induced by tri…
We report extensive first-principles calculations of the inelastic lifetime of low-energy electrons in the noble metals Cu, Ag, and Au. The quasiparticle self-energy is computed with full inclusion of exchange and correlation (xc) effects, in the framework of the GWΓapproximation of many-body theory. Although exchange…
We show that some metals and alloys (X = Cu, Ag, FeMn, or Cu and Ag combined with each other), sputtered between ferromagnetic Co and superconducting Nb, produce no change in current-perpendicular-to-plane magnetoresistance (CPP-MR) in a carefully designed CPP-spin-valve. In contrast, other metals (Ru or Au) or combin…
Charge migration along DNA molecules has attracted scientific interest for over half a century. Reports on possible high rates of charge transfer between donor and acceptor through the DNA, obtained in the last decade from solution chemistry experiments on large numbers of molecules, triggered a series of direct elect…
The frequency dependent ac conductivity and permittivity of porous lead zirconate titanate ceramic with the pore volume filled with water are shown to match the simulated electrical response of a large network of randomly positioned resistors and capacitors. Anomalous power law dispersions in conductivity and permitti…
In the last years there has been a great interest in magnetic systems formed by a cluster of transition metal ions covalently bonded via superexchange bridges, embedded in a large organic molecule. Following the synthesis and the structural and magnetic characterization of these magnetic molecules by chemists, the phy…
In the last years there has been a great interest in magnetic systems formed by a cluster of transition metal ions covalently bonded via superexchange bridges, embedded in a large organic molecule. Following the synthesis and the structural and magnetic characterization of these magnetic molecules by chemists, the phy…
The aqueous synthesis and post-preparative treatment of thiol-stabilized ZnSe colloidal nanocrystals (2−3 nm in size) have been studied. The post-preparative irradiation of the nanoparticles improves their luminescence properties leading to strong (up to 25−30% photoluminescence quantum yield) band gap UV-blue emissio…
Perovskite nanoparticles were obtained by treating alkali or alkaline-earth metals dissolved in benzyl alcohol with transition metal alkoxides, which is a novel and generally applicable route to nanosized perovskites and related materials. In the picture, the synthetic route to BaTiO3 nanocrystals is superimposed on a…
Ferroelectric BiFeO 3 thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate by pulsed-laser deposition. From the X-ray diffraction analysis, the BiFeO 3 thin film consists of perovskite single-phase, and the crystal structure shows the tetragonal structure ( c / a = 1.018) with a space group P 4 m m . It is…