Materials Literature
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Single-layer absorbers composed of sintered planar hexagonal ferrites were developed. The absorbers have 50/spl sim/90% relative bandwidth at microwave frequencies. The broadband characteristics were successfully analyzed by a quarter-wavelength resonator model, which took into account both a wavelength reduction due…
Hybrid materials which combine the electronic conductivity of conjugated polymers and the redox and optical properties of metal complexes are being developed to take advantage of synergistic electronic interactions. Many systems show a splitting of the metal redox wave analogous to that in dinuclear complexes with thr…
Flame initiated (800 °C, 10 s) or bulk thermal (2 days, 1000 °C) reactions of mixed powders of transition metal halides and CaC 2 or Al 4 C 3 produce transition metal carbides (TiC, ZrC, HfC, V 8 C 7 , NbC, TaC, Cr 3 C 2 , Mo 2 C and WC) in good yields. The carbides were characterised by X-ray powder diffraction, SEM/…
Relative permittivity studies of ceramics with a variety of compositions in the BaTiO 3 -BaZrO 3 -CaTiO 3 system showed some of them to be ferroelectric relaxors at temperatures close to 295 K. Such a favourable effect is due to the Ca 2+ for Ba 2+ cationic substitution. In addition a spontaneous classical ferroelectr…
Gold catalysts supported on iron oxide have been characterized by X-ray photoelectron spectroscopy (XPS). Depending on the method of preparation and pretreatment, different gold species have been detected on the catalyst surface. In the absence of thermal treatment, the XPS spectra of the impregnated samples show the…
Manganese compounds have many applications in areas such as catalysis, electrochemistry, and metallurgy, among others. Distinguishing between the various chemical states of manganese is an important aspect of research in many of these areas. It has been shown that the different chemical states of manganese can be iden…
Reduction of aqueous NiSO 4 , CoSO 4 and CuSO 4 with hydrazine has been investigated systematically to obtain ultrafine powders of pure nickel and cobalt, and of nickel–cobalt and nickel–copper alloys. The results show that the pH value and the temperature are the key factors to influence the reactions. When pH ≥ 10.0…
An efficient local equation-of-motion method is introduced for calculations of the mean-square half-path-length fluctuations ${\ensuremath{\sigma}}_{j}^{2}$ in multiple-scattering x-ray-absorption fine-structure Debye-Waller factors in aperiodic systems. Given a few local force constants, the method yields ${\ensurema…
Fibroblast adhesion and growth behavior were examined on various polymers coated on a poly(ethylene telephthalate) (PET) substrate. The polymers are poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylatel copolymer (PMB)s with different MPC unit compositions, and poly(2-hydroxyethyl methacrylate).…
In contrast to the solid-state structures of the individual compounds, arene-perfluoroarene face-to-face stacking and C–H‥F–C in-plane interactions dominate the solid-state structure of 1∶1 co-crystals of 1,4-bis(phenylethynyl)-tetrafluorobenzene 1b and 1,4-bis(pentafluorophenylethynyl)- benzene 1c, with this supramol…
The ruthenium hydrotalcite having cobalt cations, Ru-Co-Al-CO3 HT, is an effective heterogeneous catalyst for the oxidation of various kinds of alcohols in the presence of molecular oxygen.
Pulsed neutron diffraction investigations have been performed in the ferroelectric PZT system (PbZr 1- x Ti x O 3 ) doped with 1 wt% of Nb 2 O 5 , as a function of both temperature and composition. The study has been made in a wide range of temperatures encompassing the three known phases in Zr-rich PZT: ferroelectric…
A popular concept that describes the structure of polymer interfaces by ``intrinsic profiles'' centered around a two-dimensional surface, the ``local interface position,'' is tested by extensive Monte Carlo simulations of interfaces between demixed homopolymer phases in symmetric binary (AB) homopolymer blends, using…
The electronic structure of ${\mathrm{CrO}}_{2}$ is critically discussed in terms of the relation of existing experimental data and well converged local-spin-density approximation (LSDA) and generalized gradient approximation (GGA) calculations of the electronic structure and transport properties of this half metal ma…
We have extended our previous kinetic model for the Thermal De-NOx Process to include recent information about the branching fraction α1(T) of the NH2 + NO reaction, NH2 + NO ⟷ N2 + H2O (R1a) NH2 + NO ⟷ NNH + OH, (R1b)where α1(T) = k1b/(k1a + k1b). The values of the rate coefficients k1a(T) and k1b(T) used in the mode…
The production of organic acids in low-cost, high-efficiency fermentation processes makes available a new route to chemical production from biomass. Because of their multiple functional groups and high reactivity, organic acids can undergo a variety of reactions that are effectively catalyzed by inorganic heterogeneou…
This article explores the effects of surface area and pore volume on the electrochemical behavior of high surface area V 2 O 5 gels dried by either supercritical or ambient methods. Traditional composite electrode structures have prevented truly quantitative analysis of surface area effects in nanoscale battery materi…
SiC and Si3N4 materials were tested under various turbine engine combustion environments, chosen to represent either conventional fuel-lean or fuel-rich mixtures proposed for high speed aircraft. Representative CVD, sintered, and composite materials were evaluated in both furnace and high pressure burner rig exposure.…
ABSTRACT Different levels (5, 10, 15, 17.5 or 20% w/w of solid) of propyleneglycol alginate (PGA) were incorporated into soy protein isolate (SPI) films to form biodegradable composite films with modified physical properties. Color of the SPI films was affected (P<0.05) by the incorporation of PGA. Tensile strength…
The electromagnetic wave absorption properties of Ba M-type (BaFe/sub 12-x/(Ti/sub 0.5/Mn/sub 0.5/)/sub x/O/sub 19/) ferrite-epoxy resin composites were investigated. After measuring the complex permittivities of the samples, the regions of complex permeabilities in which the reflection loss (R.L.) becomes less than -…