Materials Literature
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We discuss some of the unique structural and electronic properties of discotic liquid crystals, particularly the nature of the ‘band structure’, and of charge injection from metal electrodes. Attempts have been made to use conducting discotic liquid crystals in electroluminescent devices and in gas sensors. The latter…
The Gourma population has a vast knowledge of medicinal plants, as demonstrated in this survey carried out between 1999 to 1991 with herbalists, traditional healers and resource persons, as well as 424 households as informants. This investigation includes 42 species of major use in native medicine for rural health car…
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…
A room temperature water model and a high temperature molten aluminum system were designed and constructed to investigate the effect of solid particles on the stabilization of foams. The average foam life was used to evaluate the stability of the foam. The effects of particle size, wetability, and concentration of the…
Spinel ferrites of the form MFe 2 O 4 (M = Mg, Co, Ni, Cu, Zn) and rhombohedral BaFe 2 O 4 have been prepared by self-propagating high-temperature synthesis (SHS) reactions from iron, cobalt, iron(III) oxide and metal(II) oxides or peroxides. The driving force for the reactions is the oxidation of iron or cobalt powde…
An analysis of the capability of porous rungsten trioxide films as a material for photocurrent generation was performed. The photogeneration properties of single‐component and films and bicomponent films were compared. The morphology, structure, fundamental absorption edge, flatband potential, vibration spectra, and p…
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…