Materials Literature
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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…
The linear viscoelastic behavior of polydisperse polypropylenes in the melt is predicted using the molecular weight distribution (MWD) as determined from gel permeation chromatography, on the basis of simplified molecular dynamics: single exponential form of the relaxation modulus of narrow fractions, double reptation…
Owing to the unstable nature of the latex compound and the strict specifications in the quality of latex products such as condoms and examination gloves, the rejection in the latex industry comes to about 10 to 15% of the rubber consumed. These latex rejects contain about 95% rubber hydrocarbon of very high quality. A…
The accurate measurement of water vapor sorption and permeation in polymers is complicated because water has a tendency to adsorb on high energy surfaces, a relatively high heat of vaporization, and a high solubility in most polymers. These issues and the difficulties they cause in the design of sorption and permeatio…
Miscibility of 30 phr loaded black-filled (N110) blends of polyethylene-vinyl acetate (EVAc, VAc content 28%) and polychloroprene (CR) are investigated through shear and dynamic deformations. Both shear (ηa) and dynamic elongational (η′E) viscosities are conducive to their miscibility as both show positive deviation f…
Three-component systems with a polypropylene (PP) matrix consisting of polar elastomer (ethylene–propylene rubber and styrene–ethylene–butylene–styrene grafted with maleic anhydride) or of polar PP (PP grafted with maleic anhydride) and filler were investigated. Three microstructures of PP–elastomer–filler hybrids wer…