Materials Literature
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Subbandgap absorption of chemical-vapor-deposition diamond films, with nitrogen contents varying from 10 to 132 ppm has been explored by the constant-photoconductivity method (CPM), photothermal-deflection spectroscopy (PDS) and electron spin resonance (ESR). The spectra measured by PDS increase monotonically and are…
The pressure phase diagram of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl is determined by measuring the intralayer and interlayer resistivities. With increase of pressure, nonmetallic behavior of resistivity is suppressed and a metallic phase is stabilized, yielding the phase reentrance near critical pressure region. Concurrently,…
Visible photoluminescence (PL) bands around 2 eV were studied in 60Co γ-irradiated (dose<1 MGy) oxygen-deficient-type amorphous SiO2 (a-SiO2) excited by 2–4 eV photons. In addition to the well-known 1.9 eV PL band due to nonbridging oxygen hole centers, another PL band was observed at 2.2 eV when excited by 3.8…
The electronic properties of carbon nanotubes having polygonized cross sections instead of purely circular ones, such as recently observed using transmission electron microscopy, are investigated with plane-wave ab initio pseudopotential local-density-functional calculations and simple tight-binding models. Strong ${\…
We have observed Raman scattering from acoustic phonons confined in Si nanocrystals. It was found that the Raman spectra depend strongly on the size of the nanocrystals and the peaks shift to higher frequencies as the size decreases. We also found that the depolarized Raman spectra appear at much lower frequencies tha…
BACKGROUND: Several perfusion balloon catheters are under investigation for local drug delivery; however, sustained tissue drug levels are difficult to achieve with these techniques. To overcome this problem, sustained-release, biodegradable nanoparticles represent a potential alternative for prolonged local delivery.…
The viscoelastic properties of various crosslinked natural rubbers, NR, were investigated by mechanical spectroscopy. The glass transition temperature, Tg, was found to be dependent on both the crosslink density and the crosslink type. Higher values of Tg were obtained for sulfur-crosslinked NR than for peroxide-cross…
Using molecular dynamics computer simulations we investigate how the glass transition and the properties of the resulting glass depend on the cooling rate with which the sample has been quenched. The system we study is a two component Lennard-Jones model which is coupled to a heat bath whose temperature is decreased f…
We report on the layer thickness dependence of Ni 2p core-level line shapes of epitaxially grown, in a layer-by-layer fashion, NiO on a single-crystal MgO (100) substrate. The results demonstrate the sensitivity of the core-level line shape to the nearest as well as next-nearest-neighbor coordination number. The resul…
Based on electrical resistivity and Hall-coefficient measurements from 2 to 370 K on slightly reduced semiconductive rutile single crystals with various oxygen deficiencies ${\mathrm{O}}_{\mathit{d}}$ from 3.7\ifmmode\times\else\texttimes\fi{}${10}^{18}$ to 1.3\ifmmode\times\else\texttimes\fi{}${10}^{19}$/${\mathrm{cm…
Overexpression of P-glycoprotein (Pgp) by tumors results in multidrug resistance (MDR) to structurally unrelated oncolytics. MDR cells may be sensitized to these oncolytics when treated with a Pgp modulator. The present study evaluates LY335979 as a modulator both in vitro and in vivo. LY335979 (0.1 microM) fully rest…
We have used a self-aligned lithographic process to fabricate magnetic tunnel junctions of ${\mathrm{La}}_{0.67}$${\mathrm{Sr}}_{0.33}$Mn${\mathrm{O}}_{3}$ down to a few micrometers in size. We have obtained a magnetoresistance ratio as large as 83% at low magnetic fields of a few tens of Oe, which correspond to the c…
We show spectroscopically that electronic energy transfer in close-packed CdSe quantum-dot (QD) solids arises from dipole-dipole interdot interactions between proximal dots. We use cw and time-resolved photoluminescence to study electronic energy transfer in optically thin and clear, close-packed QD solids prepared fr…
Two different types of amorphous carbon films were deposited on Si substrates, with film hardness of 22 GPa and 40 GPa, by pulsed laser evaporation of graphite targets. The x-ray photoemission spectra (XPS) of the C 1s core level in these films shown two components at 284.3\ifmmode\pm\else\textpm\fi{}0.1 eV and 285.2\…
We introduce an effective-medium theory for the local field and mean dielectric function of a polymer dispersed liquid crystal (PDLC) film consisting of identical spherical liquid crystal droplets dispersed in a polymer matrix. The theory takes account of the tensor nature of the dielectric response of the liquid crys…
Uni-axial anisotropy constants and uni-axial anisotropy fields of oriented polycrystalline magnets were obtained from the field-dependence of the magnetization by three methods and from torque measurements. The results from torque measurements are found to be superior to those from the intersections of magnetization c…
A comparative study has been performed concerning the magnetization behaviour of single-phase and two-phase exchange-coupled . Measurements of reversible and irreversible magnetization and magnetic viscosity have been performed on nanocrystalline samples prepared by mechanical alloying and subsequent heat treatment. M…
Since its discovery the Mössbauer effect has been a powerful probe of iron in magnetic materials and, together with neutron scattering and magnetic resonance, complements measurements of magnetic susceptibility and magnetization. The magnetic hyperfine splitting of the spectrum gives a measure of the magnetic moment o…
In this paper, fundamental and practical aspects of the hydrogenation, disproportionation, desorption and recombination (HDDR) process in Nd - Fe - B-type alloys are reviewed. Thermodynamic aspects of the process are discussed as well as the microstructural changes throughout the different stages of the process. A det…
High-performance magnetic materials are based on outstanding intrinsic magnetic properties and optimized microstructures and alloy compositions. The interactions between these three parameters in general are rather complex and cannot be treated explicitly by the theory of micromagnetism. Instead numerical methods have…