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。
Proteins belonging to the superfamily of pyridoxal 5'-phosphate-dependent enzymes are currently classified into three functional groups and five distinct structural fold types. The variation within this enzyme group creates an ideal system to investigate the relationships among amino acid sequences, folding pathways,…
The three-dimensional structures of orotidine 5'-monophosphate decarboxylases from four different organisms have been determined by X-ray crystallography. The structures reveal an active site in which the pyrimidine base and phosphate groups are rigidly held in place. Surprisingly, both pyrimidine carbonyl groups are…
New epoxy-based thermoplastics for barrier packaging are discussed here (see Figure). The polymers, poly (hydroxyaminoethers), are typically generated through reactions of various dinucleophiles with epoxy monomers. The effects of functionalization, branching, and copolymerization on the mechanical, adhesive, and barr…
Temperature-dependent optical reflectivity spectra were measured on cleaved surfaces of ${\mathrm{La}}_{0.825}{\mathrm{Sr}}_{0.175}{\mathrm{MnO}}_{3}$ single crystals up to 6.6 eV. The present result demonstrates that the exchange-gap excitation in the optical conductivity spectrum splits into two parts $(\ensuremath{…
Direct current electrical resistivity measurements on specimens with composition BaO (6−x) Fe2O3, x Sb2O3 with x having values of 0.0, 0.025, 0.05, 0.1, and 0.3, respectively, were carried out in the temperature range of 120–300 K. Chemical analyses showed the presence of Sb3+ and Sb5+ ions as well as Fe2+ and Fe3+ io…
Electrical charge-trapping characteristics have been studied in thermal oxides that were implanted with Si, experimentally using electron spin resonance (ESR), capacitance versus voltage (CV) measurements, transmission electron microscopy (TEM), atomic force microscopy (AFM), and theoretically with Density Functional…
Abstract The persistence of many seemingly metastable mineral assemblages in sediments and soils is commonly attributed to their sluggish transformation to the stable-phase assemblage. Although undoubtedly kinetics plays a major role, this study shows that thermodynamic factors, particularly surface energy, significan…
Nickel–silica nanocomposites were prepared by the sol-gel route. By subjecting these to an oxidation treatment in the temperature range 723–1023 K, nickel oxide films of estimated thicknesses in the range 0.5–1.5 nm were grown on the nickel nanoparticles. dc electrical resistivity was measured in the temperature range…
Phase transitions on the electron-doped side of the ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}{\mathrm{MnO}}_{3}$ system $(x<~0.25)$ have been investigated using high-resolution synchrotron x-ray and neutron powder-diffraction techniques, electrical transport and magnetic susceptibility measurements. At roo…
The density of states of the ideal three-dimensional Penrose tiling, a quasicrystalline model, is calculated with a resolution of 10 meV. It is not spiky. This falsifies theoretical predictions so far, that spikes of width 10–20 meV are generic for the density of states of quasicrystals, and it confirms recent experim…
Precise control of metal nanoparticle size is demonstrated to be possible for metal nanoclusters grown on resin supports. The final size and size distribution of the nanoclusters are shown to be limited by steric restrictions imposed by the three-dimensional polymer network (see Figure). This is because the nanocluste…
A comparative study of ablation plasma plumes originated from single crystal graphite (SCG) and amorphous carbon (a-C) targets during the preparation of diamond-like carbon (DLC) films by KrF excimer pulsed laser deposition (PLD) has been carried out by means of a monochromator equipped with an intensified optical mul…
A copper/air-gap interconnection structure using a sacrificial polymer and SiO/sub 2/ in a damascene process has been demonstrated. The air-gap occupies the entire intralevel volume with fully densified SiO/sub 2/ as the planar interlevel dielectric. The copper was deposited by physical vapor deposition and planarized…
Semiconducting crystalline materials that are poor conductors of heat are important as thermoelectric materials and for technological applications involving thermal management. A combination of neutron scattering, lowtemperature ultrasonic attenuation and thermal conductivity measurements are reported on single crysta…
The effects of adding small quantities of SnO 2 to the basic ZnO–Bi 2 O 3 varistor composition were studied in terms of phase reactions, microstructural development, and the formation of inversion boundaries. Scanning and transmission electron microscopy studies showed that the inversion boundaries, triggered by the a…
Convenient syntheses and X-ray crystallographic characterizations of the first bis(trimethylsilyl)amido-, methyl-, and iodozinc triorganosiloxide aggregates 1−5 are described. They are accessible by the simple reaction of ZnR′2 [R = Me, N(SiMe3)2] with the respective silanols R3SiOH (R = Me, Et, iPr), which affords th…
We present a detailed analysis of the free energy surface of a well characterized rigid model for water in supercooled states. We propose a functional form for the liquid free energy, supported by recent theoretical predictions [Y. Rosenfeld and P. Tarazona, Mol. Phys. 95, 141 (1998)], and use it to locate the positio…
The synthesis of new hybrid ferrocene and pi-extended tetrathiafulvalene (TTF) donor(1)-pi-donor(2) molecular assemblies 16a-c has been carried out by a Wittig-Horner reaction of the respective phosphonate esters 15a-c with 2-(2-ferrocenylvinyl)-9, 10-anthraquinone (18) prepared by olefination of ferrocenecarboxaldehy…
Measurements of electric- and magnetic-field-induced changes in electrical conduction indicate the coexistence of charge-ordered and ferromagnetically ordered regions in the Sr-substituted ${\mathrm{Pr}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ epitaxial films. Percolative, metal-like channels open up in this topol…
We have studied the effect of temperature and pressure on the crystallization of poly(n-octadecyl methacrylate) (PnODMA) by dielectric spectroscopy within the T range from 253 to 363 K and for pressures up to 2.5 kbars. Upon crystallization the spectrum shifts to lower frequencies and broadens considerably towards the…