Materials Literature
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The low temperature phase of single crystals of Nd$_{0.5}$Ca$_{0.5}$MnO$_3$ and Gd$_{0.5}$Ca$_{0.5}$MnO$_3$ manganites is investigated by squid magnetometry. Nd$_{0.5}$Ca$_{0.5}$MnO$_3$ undergoes a charge-ordering transition at $T_{CO}$=245K, and a long range CE-type antiferromagnetic state is established at $T_N$=145…
Sculptured thin films (STFs) are nano-engineered materials whose columnar morphology is tailored to elicit desired optical responses upon excitation. Two canonical forms of STFs have been identified. Linear constitutive relations for general STFs as unidirectionally nonhomogeneous (continuously or piecewise uniformly)…
Proposed Silicon-based quantum computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing infrastructure of the powerful Si technology. Quantitative understanding of and precise physical…
By means of micromagnetic spin dynamics calculations, a quantitative calculation is carried out to explore the mechanism of exchange bias (EB) in ferromagnetic (FM)/compensated antiferromagnetic (AFM) bilayers. The antiferromagnets with low and high Neel temperatures have been both considered, and the crossover from n…
Recent progress in theoretical understanding of magnetic anisotropy and stiffness in III-V magnetic semiconductors is exploited for predictions of magnetic domain characteristics and methods of their tuning. We evaluate the width and the energy of domain walls as well as the period of stripe domains in perpendicular f…
A rigorous two-thermostat formulation for ab-initio molecular dynamics using the fictitious Lagrangian approach is presented. It integrates the concepts of mass renormalization and temperature control for the wave functions. The new thermostat adapts to the instantaneous kinetic energy of the nuclei and thus minimizes…
LDA+DMFT is a novel computational technique for ab initio investigations of real materials with strongly correlated electrons, such as transition metals and their oxides. It combines the strength of conventional band structure theory in the local density approximation (LDA) with a modern many-body approach, the dynami…
The majority of invertebrate skeletal tissues are composed of the most stable crystalline polymorphs of CaCO(3), calcite, and/or aragonite. Here we describe a composite skeletal tissue from an ascidian in which amorphous and crystalline calcium carbonate coexist in well-defined domains separated by an organic sheath.…
Robust multilayers can be formed on solid surfaces, and subsequently destroyed by changing the environmental conditions, by the layer-by-layer sequential assembly of monomolecular films of a polyacid and polybase from aqueous solution. Interlayer hydrogen bonding produces stable multilayers up to the point where alter…
Chitosan scaffolds appear to be suitable for a variety of tissue engineering applications. This study addressed the biocompatibility of chitosan in a mouse implantation model. Porous chitosan scaffolds were implanted in mice, and animals were sacrificed after 1, 2, 4, 8, or 12 weeks. Macroscopic inspection of the impl…
In this study, we present a Monte Carlo investigation, based on the embedded atom method potential, of the $\ensuremath{\Sigma}5$ grain-boundary (GB) sliding in copper at elevated temperature. Important aspect of this approach is the implementation of simulated annealing technique. We find a variety of sliding behavio…
The fracture behavior of two different types of extruded polyamide 6 (PA6)/maleic anhydride grafted ethylene−propylene (EPM- g -MA) blends is examined by magnetic resonance imaging (MRI). TEM micrographs demonstrate a clear difference in morphology: where one blend type contains pure rubber particles dispersed in the…
The magnetic properties of Fe ions implanted into a germanium crystal by metal-vapor vacuum arc ion source were investigated using a Quantum Design SQUID magnetometer. The presence of Fe nanoclusters in Ge was verified by magnetization measurements. A Langevin fit was used to obtain the size distribution of the cluste…
The thermoreversible nature of the ionic associations in aggregates makes ionomers with a low glass transition temperature interesting candidates for thermoplastic elastomers. In this paper, a low- T g ionomer based on low molecular weight ethylene−propylene copolymers modified by maleic anhydride (MAn- g -EPM) is int…
Gas-phase photolysis of methyldisiloxanes [(CH 3 ) n H 3 - n Si] 2 O ( n = 1−3) has been achieved for the first time through absorption of ArF laser radiation at 193 nm and has been shown to yield C 1 −C 2 hydrocarbons (major volatile products), methylsilanes (minor volatile products), and solid methylsilicones with t…
The syntheses of a β,β′-fused ruthenocenoporphyrin (9) and a ferrocenoporphyrin dimer (11) are described.
Curie temperatures in ferromagnetic semiconductor superlattices are calculated self-consistently within mean-field theory and the effective bond orbital model of the superlattice band structure. Assuming a null valence-band offset and a constant average hole density of ${10}^{20}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3…
The structure of porous silicon is investigated by grazing incidence x-ray scattering. Using GISAXS (grazing incidence small-angle x-ray scattering), a systematic pore correlation is observed for all porous silicon types. The quantitative analysis of the measurement has been performed for the ${p}^{\ensuremath{-}}$-ty…
Abstract The oxidative stability of the carbon fiber‐reinforced composite of polyimide was examined, in real time, using the evolved gas analysis techniques. Off‐gas degradation products suggested the onset temperature for chain scissions to be fairly low at about 190–220°C. Based on the off‐gas products present and t…
The synthetic routes to ladder polymers that consist of benzenetetrayl subunits with oxo and methylsulfonio linkages are described. As the key intermediate, poly(phenylene oxide)s having pendant methylsulfenyl groups are prepared by copper-catalyzed oxidative polymerization of the corresponding phenols with O 2 . The…