Materials Literature
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We report on an enhanced thermoelectric figure of merit ZT=σS2T/λ (where σ is electrical conductivity, S is thermopower, T is absolute temperature, and λ is thermal conductivity) for PbTe/PbSe0.20Te0.80 superlattices (SLs) and PbTe doping SLs due to a reduction of the thermal conductivity λ parallel to the layer plane…
Continuous-wave measurements of the shear elastic constants of bcc Fe–Ga solid solutions show that the constant C44 is independent of the gallium composition while the constant 12(C11–C12) decreases linearly and extrapolates to zero at 26 at. % Ga. This result indicates that the Fe–Ga solid solution is inhomogeneous a…
Recent theoretical studies have concluded that the low formation enthalpies of intrinsic donor defects should preclude achievement of p-type conductivity in undoped ZnO grown in thermal equilibrium with a molecular oxygen reservoir. This letter demonstrates that reactive sputtering can produce intrinsic p-type ZnO, co…
Deterministic oscillations of current-induced metastable resistivity in changing voltage have been detected in La$_{0.82}$Ca$_{0.18}$MnO$_3$ single crystals. At low temperatures, below the Curie point, application of specific bias procedures switches the crystal into metastable resistivity state characterized by appea…
We demonstrate how first-principles calculations using density-functional theory (DFT) can be applied to gain insight into the molecular processes that rule the physics of materials processing. Specifically, we study the molecular beam epitaxy (MBE) of arsenic compound semiconductors. For homoepitaxy of GaAs on GaAs(0…
Straight long carbon nanofibers with a large hollow core obtained by a floating reactant method show a stacking morphology of truncated conical graphene layers, which in turn exhibit a large portion of open edges on the outer surface and also in the inner channels. Through a judicious choice of oxidation conditions, n…
We have investigated the Faraday rotation of in-plane magnetized bismuth - substituted ferrite garnet films grown by liquid phase epitaxy on (100) oriented gadolinium gallium garnet substrates. The Faraday spectra were measured for photon energies between 1.7 - 2.6 eV. To interprete the spectra, we use a model based o…
We have studied the electronic structure of 3d transition-metal- MgB_{2} alloys, Mg_{0.97}TM_{0.03}B_{2}, (TM\equiv Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) using KKR-CPA method in the atomic-sphere approximation. For unpolarized calculations, our results for Mg_{0.97}TM_{0.03}B_{2} alloys are similar to that of 3d impu…
Synthesis of a new pentahydroxamic acid bifunctional chelating agent (BCA), constructed on the aminoazaalkyl core of diethylenetriaminepentaacetic acid (DTPA), is reported. Rational modifications in the structure of DTPA, which could result in an enhancement of its chelation properties, add to the collection of diagno…
We report force measurements in thin liquid films containing charged diblock copolymers (poly( tert -butylstyrene)−poly(styrenesulfonate)) adsorbed at the film surfaces. Although the film surfaces are likely to be covered by copolymer layers with a brush structure, the observed features, both film ordering and force r…
Control over the macromolecular structural characteristics of poly(phenylsilsesquioxane) resin materials was obtained by combining the effects of surfactant addition with dynamic pH modification in aqueous condensation media. Average molecular weight, polydispersity, and the degree of condensation in the resulting pol…
The bifunctional enzyme aspartokinase-homoserine dehydrogenase I from Escherichia coli catalyzes non-consecutive reactions in the aspartate pathway of amino acid biosynthesis. Both catalytic activities are subject to allosteric regulation by the end product amino acid L-threonine. To examine the kinetics and regulatio…
Energy transfer between Ru II and Os II polypyridyl complexes covalently attached to polystyrene has been in studied in CH 3 CN. The polymer is a 1:1 styrene- p -aminomethylstyrene copolymer derivatized by amide coupling with the acid-functionalized metal complexes [M II (bpy) 2 (bpy-COOH)](PF 6 ) 2 (M II = Ru II, Os…
The direct channeling of an intermediate between enzymes that catalyze consecutive reactions in a pathway offers the possibility of an efficient, exclusive, and protected means of metabolite delivery. Aspartokinase-homoserine dehydrogenase I (AK-HDH I) from Escherichia coli is an unusual bifunctional enzyme in that it…
Monte Carlo simulations have been applied to investigate the behavior of thin polymeric films near the glass transition. Free-standing films of both linear and cyclic polymeric chains have been considered in this work. In agreement with experiments, we find that the apparent glass transition temperature of free-standi…
In this contribution we present a continuous wave (CW), pulse electron paramagnetic resonance (EPR), and pulse electron nuclear double resonance (ENDOR) study of (OEC)Co(C 6 H 5 ), where OEC is the trianion of 2,3,7,8,12,13,17,18-octaethylcorrole. To facilitate spectral assignments isotopic substitutions were employed…
High-resolution transmission electron microscopy and spatially resolved electron loss spectroscopy have revealed that a eutectic mixture of AgCl and AgI crystallizes within single walled carbon nanotubes (SWNTs) as metastable AgCl(1-)(x)I(x) 1D solid solution crystals. The incorporated halide crystals form wurzite "tu…
Polytetrahydrofuran (PTHF)/poly(1,3-dioxepane) (PDOP)/polystyrene (PSt) ABC miktoarm star copolymers were synthesized by combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization. Two different functional groups, carboxylic acid and CHBr, were capped at one end of PTHF through…
Metal ion sorption can be significantly impacted by the presence of other solutes or complexing species. In this research, macroscopic sorption studies were conducted to evaluate the effect of strongly sorbing Se(IV) and weakly sorbing Se(VI) oxyanions on cobalt(II) sorption to gamma-Al2O3. Se(IV) was found to signifi…
The structure and structural transition of silk fibroin from a wild silkworm Antheraea pernyi ( A. pernyi ), whose amino acid sequence consists of poly( l -alanine) (PLA) and a Gly-rich region, were studied with solid-state 13 C cross-polarization magic angle spinning (CP/MAS) NMR. As such, there has been limited info…