Materials Literature
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It is generally accepted that biodegradation of poly(etheruethane urea) (PEUU) involves oxidation of the polyether segments on the surface where leukocytes are adhered. The influence of dissolved oxygen, which is known to control oxidation of polymers in more traditional environments, was explored in this study. Speci…
The present study is aimed at clarifying some of the factors which affect the formation and direction of a liquid jet in a collapsing cavity and the pressures induced on a nearby rigid boundary. The flow can be accurately represented by a velocity potential leading to the use of boundary integral methods to compute bu…
Using high-resolution electron energy-loss spectroscopy the surface-phonon dispersion of graphite has been determined in the \ensuremath{\Gamma}K direction over the whole energy range and the whole Brillouin zone. Born--von Karman model calculations are used to describe the dispersion relations. An unexpected result i…
Spherical, monodispersed, ferromagnetic, metallic particles of different compositions were obtained by the polyol process with a mean radius ranging from 30 nm to 1 μm. The microwave permeability of metallic particles-dielectric matrix composites were studied in the range of 0.1–18 GHz. In the wide particle size range…
Strong photoluminescence from silicon-ion-implanted thermal ${\mathrm{SiO}}_{2}$ film was investigated under various conditions. The photoluminescence spectrum of as-implanted samples or samples annealed in ${\mathrm{N}}_{2}$ at a temperature below 1000 \ifmmode^\circ\else\textdegree\fi{}C consists of three bands cent…
We have studied photoluminescence (PL) properties of surface-oxidized Si nanocrystals fabricated with a ${\mathrm{SiH}}_{4}$ plasma cell. The size dependence of the PL spectrum, the PL decay dynamics, and site-selective excitation spectroscopy show that the efficient and broad PL band around \ensuremath{\sim}1.65 eV o…
Thin-film ferroelectric capacitors consisting of PbZr0.53Ti0.47O3 sandwiched between La0.5Sr0.5CoO3 electrodes have been deposited using pulsed laser deposition. The combination of oxidic perovskite-type materials results in capacitors with a coercive field (Ec) which is comparable with values for bulk ceramics. Textu…
Effects of chemical and external pressures have been investigated on the two types of charge-ordering (CO) systems of perovskite manganites with the use of single-crystal specimens: One is ${\mathrm{Nd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Sr}}_{\mathrm{x}}$${\mathrm{MnO}}_{3}$ with moderate CO instability…
Using a semiempirical tight-binding approach modified through introduction of a deformation potential, we have calculated the effects of uniaxial stress on the electronic density of states of carbon tubules. For zigzag tubules (n,0) the gap varies linearly with stress and independently of diameter: |${\mathrm{dE}}_{\m…
Polarization-dependent far-infrared reflectivity measurements were carried out on single crystals of anatase ${\mathrm{TiO}}_{2}$ . The results were analyzed to yield the dielectric dispersion properties of anatase in the lattice fundamentals regime. The frequencies (in ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ ) of…
The effect of nitrogen addition on the structural and electronic properties of hydrogenated amorphous carbon (a-C:H) films has been characterized in terms of its composition, sp3 bonding fraction, infrared and Raman spectra, optical band gap, conductivity, and paramagnetic defect. The variation of conductivity with ni…
Heat transport in 20–300 nm thick dielectric films is characterized in the temperature range of 78–400 K using the 3ω method. SiO2 and SiNx films are deposited on Si substrates at 300 °C using plasma enhanced chemical vapor deposition (PECVD). For films >100 nm thick, the thermal conductivity shows little depen…
Collagen, the major structural protein of the extracellular matrix in animals, is a versatile biomaterial used in various tissue engineering applications. Cross-linking influences the mechanical properties, resorption kinetics, and biocompatibility of collagen-based biomaterials. In this study, we evaluated the effect…
Durch Umsetzen von Tetrachlorsilan mit Bis(trimethylsilyl)carbodiimid im Verhältnis 1:2 und nachfolgendes Tempern des Reaktionsproduktes bei 400°C oder 900°C sind die ersten kristallinen ternären Si‐C‐N‐Feststoffe, Siliciumdicarbodiimid, SiC 2 N 4 , bzw. Silicium(carbodiimid)nitrid, Si 2 CN 4 in nahezu quantitativer A…
The in vitro degradation characteristics of poly(anhydride-imides) containing trimellitylimidoglycine, with either 1,6-bis(carboxyphenoxy)hexane or sebacic acid, were assessed. The copolymers contained 10, 30, or 50 mol % of the imide monomer, trimellitylimidoglycine. Degradation was pH-sensitive, being enhanced under…
Rings containing 144 Mo atoms are linked by Mo-O-Mo bridges (depicted on the right) to form chains in the polyoxometalate presented here. The blue mixed-valent compound is formed by the reduction with iron powder of an acidified solution of polymolybdate in the presence of Na+ ions.
The enantiopure europium and terbium complexes of the macrocyclic ligand 1 are conformationally rigid in solution. The cationic terbium complex gives rise to an intense circularly polarized emission, which offers much promise for its use as a chiral probe.
Variations in diatom communities between river habitats might have ramifications for their use as bioindicators and for the assessment of their contribution to aquatic biodiversity. Diatoms therefore were sampled from similar surface areas of the epilithon and bryophytes in 24 hill-streams in the Nepalese Himalaya to…
Collagen fibers form the structural units of connective tissue throughout the body, transmitting force, maintaining shape, and providing a scaffold for cells. Our laboratory has studied collagen self-assembly since the 1970s. In this study, collagen fibers were self-assembled from molecular collagen solutions and then…
We present a detailed molecular-dynamics study of the melting, freezing, and coalescence of gold nanoclusters within the framework of the embedded-atom method. Concerning melting, we find the process to first affect the surface (``premelting''), then to proceed inwards. The curve for the melting temperature vs cluster…