Materials Literature
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The wet grinding of alumina with HCl for forming stable dispersions was investigated in a laboratory ball mill. Acid concentrations in the range 1-10 wt % of dry alumina do not influence the wet-milling product. The viscosity of the alumina slurries produced from the wet-milling process is strongly dependent on pH whi…
Five oleanane-type triterpenoid saponins, gymnemic acids VIII-XII as antisweet principles were isolated from the leaves of Gymnema sylvestre (Asclepiadaceae). Their structures were established on the basis of spectral and chemical evidence. They were characterized as glucosideuronic acid derivatives of gymnemagenin ac…
Reaction of AgNO3 with [15]aneS2O3 followed by addition of NH4PF6 affords the complexes [Agn([15]aneS2O3)n](PF6)n and [Ag2([15]aneS2O3)3](PF6)2; the complex [Agn([15]aneS2O3)n]n+ is an S-bridged linear-chain polymer of [Ag([15]aneS2O3)]+ units with formal S2O3Sbridge coordination at AgI, while the binuclear species [A…
The solubility of silica gel in distilled water and dilute and alkaline solutions has been investigated. The solubility has been studied as a function of the pH of the gel preparation, pHs, and of the pH of the dissolution media, pHL. A kinetic model for the dissolution process has been developed that permits the dete…
Optical and magnetic-circular-dichroism--optically-detected-magnetic-resonance studies have been carried out on Co-doped ${\mathrm{LiGa}}_{5}$${\mathrm{O}}_{8}$. The Co ions are found to be predominantly in the 2+ charge state and to substitute for tetrahedrally coordinated ${\mathrm{Ga}}^{3+}$ in the ${\mathrm{LiGa}}…
The crystal structure of cerussite, PbCO 3 , was refined with 669 merged single-crystal neutron data [ F 0 > 3σ( F 0 )] to R = 0.032, R w = 0.025 (space group Pmcn ; a = 5.179(1), b = 8.492(3), c = 6.141(2); Z = 4). – Cerussite belongs to the aragonite-type compounds. The weak aplanarity of the carbonate group, d =…
Optical microscopy, crystal growth kinetics and induction time measurements have been utilised to characterise the influence of n-alkanoic acids on the crystallisation of adipic acid from aqueous solution. The kinetic and morphological data are consistent with a structural model in which the added n-alkanoic acids occ…
Layered structures of the alkali-metal intercalates of hydrated vanadium oxides A0.3V2O5·nH2O (A = Na, K, Rb, Cs and NH4) have been studied by the X-ray Rietveld method and electron diffraction. Structural analysis was performed for both hydrated and dehydrated phases, in which the (00l) reflections were used in the R…
Proteases with apparent molecular weights of 47, 40, 34 and 32 kD were identified in cellfree extracellular products (ECP) of Flexibacter colurnnaris by using substrate SDS-polyacrylamide gel electrophoresis. Similar protease profiles were associated with ECP collected at intervals during several days in culture. Furt…
The authors report on the practical aspects of acoustic diagnoses of gas insulated substations (GIS). Thirty-eight tests have been carried out during factory testing, commissioning testing, and service. The number of flaws revealed in the tests varies considerably. The flaw frequency in a GIS probably reflects the car…
The luminescence properties of hydrated Eu3+-exchanged zeolite A at 4.2 K are reported. The luminescence spectra indicate that the Eu3+ ions in the zeolite cages are, unlike Eu3+ ions in hydrated zeolite Y, bound to framework oxygens. High-resolution measurements suggest that Eu3+ ions are located in two sites in the…
The crystal and molecular structure of the polythiophene 4 and its charge-transfer complex with tetracyanoquinodimethane (TCNQ) have been determined. Crystal data: 4, C10H4S4, M= 252.38, monoclinic, P21/n, a= 11.462(1), b= 4.026(1), c= 10.437(1)Å, β= 103.77(1)°, V= 467.8(1)Å3, Z= 2, D= 1.792 g cm–3; 4·(TCNQ), C22H8N4S…
The crystal structures of tetranuclear butterfly clusters of CuI, AgI and the mixed metal AgI2CuI2 compound as obtained by reaction of the metal acetates with 2-mercaptothiazoline, and subsequent treatment of the insoluble polymeric clusters with organic bases are reported.
Purification of aldehyde oxidoreductase from C. thermoaceticum, the first detected enzyme able to reduce reversibly non-activated carboxylic acids to the corresponding aldehydes (White, H., Strobl, G., Feicht, R. & Simon, H. (1989) Eur. J. Biochem. 184, 89-96), results in the generation of multiple forms of the enzyme…
The microstructure of two commercial alloys MA956 and MA957 obtained by mechanical alloying has been investigated. These Oxide Dispersion Strengthened (ODS) ferritic materials display particular microstructures and behaviours under heat treatments. Recrystallization phenomena depends on a lot of material processing pa…
Abstraet-Supcrhydrophohic FEP-Teflon was prepared by argon ion etching followed by oxygen glow discharge treatment of commercially available FEP-Teflon sheet material. This combined treatment yielded an increase in water contact angle from 109° to > 140°. Ion etching alone caused a small increase in surface roughness…
An empirical potential-energy function comprising two- and three-body terms, whose parameters have been determined from the properties of solid silicon, is used to study the structures and energies of silicon microclusters. For small clusters, densely packed (non-diamond) structures are found which are in broad agreem…
Alumina-boria samples with B : (B + Al) 0–50 atom% have been prepared by an unconventional procedure consisting of the reductive decomposition of the mixture of nitrates in the presence of glycerol X-ray diffraction (XRD)-amorphous samples having surface areas of 380–470 m2 g–1 were obtained after calcination at 673 K…
Abstract The antioedematogenic activity of two natural pregnane compounds from Mandevilla velutina was evaluated against croton oil‐induced ear oedema in mice. For comparison the effects of nonsteroidal (indomethacin, phenidone and BW 755C) and steroidal (dexamethasone) antiinflammatory drugs were analysed. The purifi…
The authors present guidelines for analyzing harmonics and transient overvoltages generated by arc furnaces. Computer simulation techniques for creating accurate models for the analysis of arc furnace power systems are also discussed. Simulation guidelines are outlined in detail to assist the power systems engineer in…