Materials Literature
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The bandgap energy as a function of temperature has been determined for lead iodide. The monocrystal was obtained in a vacuum sealed quartz ampoule inside a vertical furnace by Bridgman's method. The optical transmittance measurement enables to evaluate the values of Eg. By a fitting procedure of Eg as a function of t…
Basic regularities of silicon nitride based materials microstructure formation and development in interrelation with processing conditions, type of sintering additives, and starting powders properties are discussed. Models of abnormal or exaggerated grain growth are critically reassessed. Results of several model expe…
The Al2O3-ZrO2 composite was studied by impedance spectroscopy, a non destructive technique that was found to be sensitive to the composite's microstructure. The observed decrease in the zirconia grain and grain boundary conductivities points to compression on zirconia grain by alumina matrix. This effect increased wi…
Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthe…
O. Haas and E. J. Cairns, Annu. Rep. Prog. Chem., Sect. C: Phys. Chem., 1999, 95, 163 DOI: 10.1039/PC095163
Abstract Epilithon, epiphyton, epipelon, epipsammon and plocon diatom samples and water chemistry samples were collected bimonthly from 11 stations along the Mesta River, Bulgaria between December 1989 and April 1991. Principal component analysis (PCA), correlation, and dominance analysis were employed for describing…
By electrochemical adsorption of glucose oxidase (GO) on a polypyrrole (PPy) nanotubular layer, a glucose biosensor has been fabricated. PPy microtubules can be synthesized by oxidative polymerization of the pyrrole monomer within the pores of a polycarbonate template. The activities of immobilized GO are investigated…
The filter feeding oligotrich ciliate Strobilidium lacustris, the raptorial prostome ciliate Balanion planctonicu~n and the diffusion feeding scuticociliate Histiobalantium bodamicurn could be cultivated for months/years on a sole &et of Cryptomonas sp., whereas the diatom Stephanodiscus hantzschii did not support the…
The phase state and the kinetics of the order-to-order transitions have been studied in a series of poly(isoprene-b-ethylene oxide) (PI-PEO) diblock copolymers with a PI volume fraction in the range 0.25<fPI<0.92, using small angle x-ray scattering (SAXS), and rheology. The mean-field theory (MFT) struct…
The complex Rh(PPh3)3Cl immobilized on MCM-41 modified with (OEt)3Si(CH2)3PPh2 results in a stable hydrogenation catalyst with turnover frequency (TOF) three times higher than that of Rh(PPh3)3Cl in the hydrogenation of cyclohexene.
The exchange interaction of polaronic carriers with localized spins leads to a ferromagnetic/paramagnetic transition in doped charge-transfer insulators with strong electron-phonon coupling. The relative strength of the exchange and electron-phonon interactions determines whether the transition is first or second orde…
First-principles total-energy calculations are carried out for (001) surfaces of the cubic perovskite ATiO3 compounds PbTiO3, BaTiO3, and SrTiO3. Both AO-terminated and TiO2-terminated surfaces are considered, and fully-relaxed atomic configurations are determined. In general, BaTiO3 and SrTiO3 are found to have a rat…
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…
An Mg/Al and a Mg/Ga layered double hydroxide (LDH) were synthesized by using the coprecipitation method and calcined at a variety of temperatures. The starting LDHs and their calcination products (mixtures of oxides and spinels) were characterized by X-ray diffraction, solid-state NMR and IR spectroscopies and thermo…
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…