Materials Literature
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Abstract Gold nanoparticles can be deposited on several metal oxides by liquid phase grafting (LG) of dimethyl gold acetylacetonate. They exhibit high catalytic activities for the oxidation of CO and of H2 at low temperatures, below and above 273 K, respectively.
Pulsed magnetic fields up to 50 T and neutron-diffraction measurements have been used in a systematic investigation of the lattice and magnetic factors contributing to the charge-melting transition in ${L}_{1/2}{\mathrm{Ca}}_{1/2}{\mathrm{MnO}}_{3}$ perovskites $(L:\stackrel{\ensuremath{\rightarrow}}{Y}\mathrm{La}).$…
As part of a program to develop high temperature/high performance structural resins for applications on a Mach 2.4 high speed civil transport, a phenylethynyl terminated imide oligomer designated PETI-5 has been under investigation. The oligomer was prepared at a calculated number average molecular weight of about 500…
The structure of canavalin was refined to 2.1 and 2.0 A resolution in cubic and hexagonal crystals of space group P2(1)3 and P6(3), respectively. The threefold molecular symmetry is expressed in the symmetry of both crystals, where each identical subunit is an asymmetric unit. The canavalin subunit consists of two ver…
The effects of fluorinated acrylate monomers on the electro-optical and morphological properties of polymer dispersed liquid crystal (PDLC) films are reported. The partial fluorination of host polymer matrices resulted in improved optical properties and better defined morphologies. An enhancement in contrast ratio was…
The trap-related photoluminescence dynamics in CdSxSe1−x nanocrystals (for x=0.24 and x=0.74) in glass were studied in the temperature interval 10–300 K. A close link between the temperature behavior of the photoluminescence decay rate and that of the photoluminescence efficiency was found, which indicates a dominant…
The chemical diffusivity of 1.8 mol% aluminum‐doped BaTiO 3−δ was measured on single‐crystal specimens, as a function of ambient oxygen partial pressure, in the range 10 −18 atm ≤ P O2 ≤ 1 atm and at temperatures of 800°≤ T ≤ 1100°C, via a conductivity‐relaxation technique. As in the polycrystalline, undoped BaTiO 3−δ…
The inhibitive action of triazoles on the corrosion of mild steel has been studied through weight loss and various electrochemical techniques. Results obtained show that these organic compounds are very good inhibitors. Triazoles are able to reduce the corrosion of steel more effectively in 1M HCl than in 0·5M H2 SO4…
Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.
It is demonstrated that the susceptibility spectra of supercooled propylene carbonate as measured by depolarized-light scattering, dielectric-loss, and incoherent quasielastic neutron-scattering spectroscopy within the GHz window are simultaneously described by the solutions of a two-component schematic model of the m…
The structure, microstructure, and magnetic properties of nanostructured Sm2Co17-based powders synthesized by mechanically milling and subsequent annealing have been systematically studied. It has been found that a nanoscale 2:17 phase with an average grain size of about 30 nm is developed within the powders, which ha…
In this paper, a frequency-selective structure based on guided-mode resonance effects in all-dielectric waveguide gratings is demonstrated theoretically and verified experimentally. Reflection (band-stop) filters with high efficiency, extended low-sideband reflection, and symmetric line shapes are designed by embeddin…
Ferroelectric properties of the metal/ferroelectric/insulator/semiconductor (MFIS) structure were investigated using the Pt/YMnO3/Y2O3/Si structure. The ferroelectric C–V hysteresis was observed for not only the Pt/YMnO3(0001)/Y2O3/Si capacitor but also the Pt/amorphousYMnO3/Y2O3/Si capacitor. The polarization evaluat…
Ferroelectric properties of a Pb(Zi, Ti)O 3 (PZT) capacitor with thin SrRuO 3 (SRO) films within both electrodes were investigated in detail. Thin SRO films of 10 nm thickness markedly improve the electrical performance, such as switching charge (Qsw), saturation characteristics of the hysteresis curve and imprint per…
Fullerenes and single-wall carbon nanotubes (SWNTs) have been produced for the first time by the high-temperature pulsed arc-discharge technique, which has developed in this laboratory. Fullerenes are identified quantitatively by high-performance liquid chromatography (HPLC), and scanning electron microscopy (SEM) and…
A different phase-separation process is capable of producing a composite system consisting of a very thin layer of liquid crystal in contact with a similarly thin layer of polymer. The morphology of the polymer depends on the composition of the prepolymer-liquid crystal mixture and the rate of polymerization. A simple…
Pyruvate kinase (PK; EC 2.7.1.40) of Thermoproteus tenax was purified to homogeneity, and its coding gene was cloned and expressed in Escherichia coli. It represents a homomeric tetramer with a molecular mass of 49 kDa per subunit. PK exhibits positive binding cooperativity with respect to phosphoenolpyruvate and meta…
We report high-resolution x-ray-absorption near-edge structure measurements at the Mn K edge as a function of temperature, for ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ samples, with a focus mainly on the pre-edge region. Small peaks labeled ${A}_{1}--{A}_{3}$ are observed which correspond…
Iron–carbon nanocomposite thin films with iron concentrations ranging from 12 to 74 at. % were grown by ion-beam sputtering codeposition at different substrate temperatures. The microstructure of the films was characterized by transmission electron microscopy, atomic force microscopy, extended x-ray absorption fine st…
The problem of the low-temperature resistance of granular films of manganites with nanometric grain sizes is addressed. The observed upturn in the low-temperature resistance is understood in terms of charging effects. However, the standard Coulomb blockade scenario does not describe the observed dependence of the char…