Materials Literature
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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…
Abstract During the last thirty years the research field of surface science with its various disciplines has progressively played a more and more important role in the field of catalysis. The main focus of attention for a long time was research on metal surfaces, on which, in time, the whole spectrum of developed surf…
Nonionic polyethylene oxide surfactants are versatile structure-directing agents for the assembly of mesoporous molecular sieves, but their greatest benefit may lie in their ability to control the pore size of the mesostructure by the assembly temperature (see dependence of pore diameter R on temperature shown on the…
The analysis of the infrared and ligand field spectra of COM 2 O 4 spinels reveals that the ionicity of these compounds varies in the following order aluminate > gallate > ferrite and chromite > rhodite and cobaltite. A linear relation has been established between the Δ(LO‐TO) 1 splitting, Racah parameter and…
A systematic investigation of the ground-state geometries and stabilities of clusters made by employing ab initio density-based molecular dynamics is reported. Although in the solid-state form, the 50:50 alloy takes on a B32-ordered structure, no evidence for such ordering has been seen for small clusters. Instead the…
Porous silicon treated by amine immersion and then rapid thermal oxidation results in a photoluminescence peak shift from ∼650 nm (red light) to a stable and intense ∼520 nm blue-green light. The amine immersion may catalyze a process during rapid thermal oxidation that both reduces the sizes of Si cores and more effe…
Optical amplification at 1.083 μm with neodymium-doped chalcogenide fiber is observed. The thermal and spectroscopic properties of a new chalcogenide glass system are measured in view of its potential use as a rare-earth host. A maximum internal gain of 6.8 dB is achieved for a pump power of 180 mW.
We have simulated by ab initio constant pressure molecular dynamics the solid-state polymerization of acetylene recently observed experimentally in the pressure range 3.5--14 GPa. We have found a massive polymerization only at much higher pressure (25 GPa). However, we have also found that a triplet exciton self-trapp…
We show that the crossover from exponential to nonexponential behavior displayed in the short-time range by the local segmental relaxation in polymers leads to the existence of a temperature ${T}^{*}$ at which the dynamics changes from independent to cooperative. ${T}^{*}$ depends on the C-C rotational barrier in the…
A flat, freely suspended film of smectic-A liquid crystal supports a pressure difference, \ensuremath{\Delta}p, across its two free surfaces. The size of its meniscus is about 10 \ensuremath{\mu}m, 2 orders of magnitude smaller than the capillary length, and its profile is predicted to be circular, in accordance with…
Photoluminescence (PL), electron spin resonance (ESR), and high resolution transmission electron microscopy (HRTEM) were used to investigate the luminescence mechanism in Si nanocrystals. Si ions were implanted in SiO2 films at 190 keV to a dose of 3×1017/cm2.An intense photoluminescence (PL) band at 755 nm (1.65 eV)…