Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Surfaces eroded by ion-sputtering are sometimes observed to develop morphologies which are either ripple (periodic), or rough (non-periodic). We introduce a discrete stochastic model that allows us to interpret these experimental observations within a unified framework. We find that a periodic ripple morphology charac…
Abstract Mechanical and rheological properties of blends of polypropylene (PP) and linear polyethylene (PE) were studied, with particular attention to the effects of aging of such mixtures. These two olefin polymers are basically incompatible. In PP‐rich blends, addition of highdensity PE (HDPE) causes only a slight d…
The crystal structure of the Glu-105-->Gly mutant of catabolic ornithine transcarbamoylase (OTCase; carbamoyl phosphate + L-ornithine = orthophosphate + L-citrulline, EC 2.1.3.3) from Pseudomonas aeruginosa has been determined at 3.0-A resolution. This mutant is blocked in the active R (relaxed) state. The structure w…
Surface plasmon dispersion on Pd(110) was investigated along the high-symmetry directions (110) and (001) with angle-resolved electron-energy-loss spectroscopy. A large negative initial dispersion with transferred momentum is found in spite of the strong shift of plasmon and surface plasmon frequencies induced by the…
The temperature dependence of the yield stress of diamond is predicted from existing data of crystals with diamond or diamondlike structure: silicon, germanium, and silicon carbide.Received 1 June 1995DOI:https://doi.org/10.1103/PhysRevLett.75.3470©1995 American Physical Society
We report pressure-dependent optical studies for different sized CdS x Se 1-x nanocrystals embedded in a glass matrix. The increase in the phase stability in going from wurtzite to rock salt structure is reversible and size dependent. Different possible sources such as strain from defects, semiconductor-to-glass-matri…
We report the effect of hydrostatic pressure up to 8 kbar on magnetoelastic, magnetic, and transport properties in the temperature range 10–300 K. An increase of Curie temperature Tc with pressure ΔTc/Δp=2.6 K/kbar was determined from ac susceptibility measurements. The anomalies in resistivity and magnetovolume effec…
The valence band offsets at the heterointerfaces of the CdF2/CaF2/Si(111) structure grown by molecular beam epitaxy were evaluated using x-ray photoelectron spectroscopy, and the energy band diagram of this heterostructure was proposed. It was found that the interface of CdF2/CaF2 has large conduction band offset: 2.9…
Crystallization of a suspension of hard spherical polymer particles is measured by following the evolution of the main Bragg reflection from the close-packed planes. Crystal growth, evident below the melting concentration, is effectively suppressed at higher concentrations due to superlinear rates of crystal addition.…
Unlike conventional crystals, quasicrystals are predicted to be elastically isotropic. To confirm this prediction experimentally, one must distinguish the quasicrystal from nearly isotropic crystals, which requires a high degree of precision. We report the use of resonant ultrasound spectroscopy to determine that the…
Carbon nitride thin films have been successfully grown on nickel substrates by a novel arc-plasma jet chemical vapor deposition. These films were characterized by Auger electron spectroscopy, transmission electron microscopy, and Raman spectroscopy. Small grains (∼0.1 μm) as well as nanocrystallites found in the films…
The forces of capillary interaction between two thin cylindrical rods or two spherical particles placed at a liquid/air interface and immersed partially in the liquid are measured by a sensitive torsion microbalance. Cylindrical rods of radii 50, 165, and 365 \ensuremath{\mu}m are used. The spheres have radius 600 \en…
To study the incorporation of nitrogen, diamond films were prepared by chemical vapor deposition homoepitaxially on {100} and {111} oriented diamond substrates. 50 ppm of isotopic 15N2 was added to the process gas. Nuclear reaction analysis was applied to determine quantitatively the concentration of incorporated 15N.…
ac initial magnetic susceptibility, thermal expansion, and magnetostriction measurements were performed on a polycrystal of ${\mathrm{La}}_{0.60}{\mathrm{Y}}_{0.07}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ manganese oxide. We observed a spontaneous volume magnetic contribution ( $\ensuremath{\cong}1\ifmmode\times\else\t…
Als erster Aquakomplex eines Elements der Gruppe 15 konnte das [Bi(H 2 O) 9 ] 3+ ‐Ion im Bismuttrifluormethansulfonat‐Enneahydrat nachgewiesen werden. Damit schließt sich die letzte Lücke in der Systematik von Aquakomplexen der Hauptgruppenmetalle. Das zentrale Bi 3+ ‐Ion im C 3h ‐symmetrischen Koordinationspolyeder ‐…
Abstract Eine Schlüsselreaktion der belebten und unbelebten Welt ist die gesteuerte Verknüpfung von einfachen (molekularen) Bausteinen, eine Reaktion, mit der man grundsätzlich mesoskopische Gebilde, z.B. solche mit Hohlräumen und beliebigen gewünschten Eigenschaften, erzeugen kann, aber auch Verbindungen mit typische…
Visible photoluminescence from porous silicon induced by infrared multiphoton excitation was observed at room temperature. Luminescence resulted from carrier excitations in the surface region of the sample. With the pump in the mid-infrared, excitation was effective only when the pump frequency was near resonance with…
A pyrrole ring of a porphyrin as an intramolecular proton donor: compound 1 (depicted below), with a deprotonated pyrrole ring, has been isolated as an intermediate in the oxidative transformation of the corresponding air-sensitive 21-telluraporphyrin into 21-oxaporphyrin.
Abstract Since the fundamental works of D. C. Bradley and R. C. Mehrotra, metal alkoxides have attracted attention because of the diversity of their low‐ and high‐molecular‐weight structures; they are also generating increasing interest as precursor compounds for solving technical materials problems. The understanding…
The potential energy surface (PES) of dissociative adsorption of H_2 on Pd(100) is investigated using density functional theory and the full-potential linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are identified which have a vanishing energy barrier. A pronounced dependence of the potenti…