Materials Literature
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The electron field emission, from silicon tip arrays with layer structures on their surfaces, was investigated. The main task of the study was to enhance field emission. The n–Si–SiO2, n–Si–Cs–SiO2,n–Si–SiO2–Si*–SiO2,n–Si–Si3N4–Si*–SiO2, etc., were among the different prepared layered structures. The thicknesses of di…
The crude dry latex of Calotropis procerapossesses a potent antiinflammatory activity. The antiinflammatory activity of petroleum ether, acetone, methanol and aqueous extracts of dry latex of Calotropis procera was tested in the carrageenan induced rat paw oedema model. All the fractions exhibited antiinflammatory act…
An overview of progress and implications of recent technological advances in mechanochemical processing of ferrites is presented. We discuss the potential for applications of mechanical activation by induced phase transformations and chemical reactions in soft and hard ferrite materials through enhancement of structur…
Micromagnetic Barkhausen emissions have been measured from a number of specimens of Cr-Mo steel in order to study the effects of creep. Creep causes changes in the microstructure of materials as a result of exposure to a high temperature and pressure. Scanning electron micrographs showed that all the specimens were at…
Trimethylamine has been used in the growth of compound semiconductors either through the formation of an adduct, as in trimethylamine allane, or as a possible growth reactant. The kinetics of the gas‐phase decomposition and dominant reaction products relevant to these applications were determined in this study. The mu…
A comprehensive geochemical and palaeobotanical study of the lacustrine sediments of Lake Nôm mejärv from industrialized NE Estonia establishes the links between the nature and intensity of human activities and their impacts on the state and structure of the lake ecosystem. In cores of sediment formed during the last…
A series of compounds LaCr1—xNixO3 (x = 0 to 1) with perovskite structure are synthesized by a citrate process and the crystal structures of these compounds are determined. A phase transition in this series of compounds occurs in the region of x = 0.6 to 0.7. The valence states of chromium and nickel ions in LaCrO3, L…
Dielectric study of phase transitions in SrTiO3 -PbTiO3 ceramic samples with PbTiO3 content x ranging from 0.002 up to 0.3 is reported. It is shown that there is a ferroelectric phase transition for x value as low as 0.005. At low x the transition temperature TC varies as (x-xc)1/2 with xc = 0.002.
The synthesis and characterization of nine trinuclear, mixed metal complexes of the type [LV{&mgr;-(PhO)(2)PO(2)}(3)](2)M, where the vanadium is in the 3+ oxidation state, L = hydrotris(pyrazolyl)borate, and M = Ba(II) (1), Ca(II) (2), Mg(II) (3), Mn(II) (4), Co(II) (5), Ni(II) (6), Fe(II) (7), 2 Na(I) (8), Al(III) (9…
Commercial poly(ethylene terephthalate) yarn was heat set at various temperatures between 100° and 255°C, while held in the taut and slack states, respectively. The lattice parameters and crystal sizes of the as-drawn and heat-set fibers were measured with the help of wide-angle x-ray scattering while the long period…
A new method has been developed to determine the surface anchoring strength W and the tilt θt of the nematic director from the normal to a curved nematic–air interface. This method is based on the comparison of interference textures obtained by polarization microscopy experiments to numerical simulations of nematic li…
Several factors must be taken into account when deciding which specimen preparation technique(s) to use. These factors include the amount of material available, ease of preparing this material due to its properties and familiarity, location and size of the region of interest, amount of information sought, facilities a…
Abstract Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locati…
Abstract The effect of combinations of zinc borate with ammonium octamolybdate or zinc stannate on smoke suppression upon combustion of flexible PVC was studied. Effects on Oxygen Index and on residual char after ten minutes at 560°C were also evaluated. These studies were done using both a conventional dioctyl phthal…
Some effects of the rare-earth ions on the properties of the polycrystalline stoichiometric ferrite with formula Ni0.7Zn0.3Fe1.98R0.02O4(R=Yb, Er, Dy, Tb, Gd, Sm and Ce) are described. The results obtained reveal that by introducing a relatively small amount of R2O3 instead of Fe2O3, an important modification of both…
Ni0.65 Zn0.35 Fe2 O4, with high density and fine grain size, is a desirable composition for applications of high frequency switching power supplies. This composition has been studied under different sintering conditions. Observed changes in density, grain size and microstructure in these ferrites have been correlated…
The growth rate kinetics of crystallization of aluminum trihydroxide from caustic aluminate solutions of aluminum−air batteries are studied in a laboratory batch isothermal precipitator. A method using high seed charges varying from 200 to 800 kg of Al(OH) 3 per m 3 of aluminate solutions is developed for the rapid de…
ABSTRACT Rice hulls were pretreated with an alkaline (pH 11.5) solution of hydrogen peroxide (1%) and then extruded. Pretreatment of rice hulls (4% db) at 50°C for 12 hr promoted 94.4% silica reduction, caused lignin solubilization and increased water absorption index (54%) and swollen volume (44%). The effects of tem…
Starting from pheophorbide a methyl ester (5), a degradation product of chlorophyll a, routes for the preparation of 3-vinylporphyrins 6 and 9 and of an [A,C]-divinylporphyrin 16 are described. These porphyrins were obtained as a result of chemical modification of 5 on ring D and the exocyclic ring E. Diels–Alder reac…
Part II of this series reports on an experimental investigation to establish the relationship between mechanical properties of fused composites and those of the outer and fusible interlining fabrics. A set of equations is proposed to predict low stress mechanical properties of fused composites from those of the outer…