Correlation between synthesis conditions, coherently diffracting domain size and cubic phase stabilization in barium titanate

The Constant Rate Thermal Analysis method has been used under different experimental conditions to obtain barium titanate powder of very small grain size. Both a crystallographic and a dielectric study ham been carried out on samples sintered at different temperatures. It is deduced that the formation of small coherently diffracting domains is improved by the generation of oxygen vacancies and the cubic phase stabilization depends on the coherently diffracting domain size rather than on the particle size.     

Statistical analysis of bend strength data according to different evaluation methods

The strength values obtained in four series of bend tests on two monolithic ceramic materials have been statistically evaluated. Statistical mapping procedures were used to check whether a Weibull distribution fits the strength data. Where this has been found to be the case, the value of the Weibull parameters determined according to different evaluation methods fall within each other's confidence interval. The values of the modulus m and of the characteristic strength σ₀ of the two-parameter distribution can differ significantly from the corresponding values in the three-parameter distribution.     

Micellar polymerisation of ionic surfactants studied by conductimetry

The micellar polymerisation of ionic surfactants such as allyldodecyl-dimethylammonium bromide and 3-dodecyl-1-vinyl imidazolium iodide has been studied by conductimetry in aqueous solution. The polymerisation was carried out using two different sources of γ rays directed into solutions of surfactant above the critical micellar concentration. Conductimetry is shown to be a very good physicochemical method for analysis of these solutions. The results showed different behaviour for the two surfactants, which has highlighted a change in the structure of their aggregates which led to the assumption of an interaction between the polymers of high mass and different products of the polymerisation (oligomers, products of degradation, monomers etc.). Ultrafiltration experiments coupled with ¹H-NMR and conductivity analysis confirm these assumptions.     

HYDROCARBON POTENTIAL OF NORTHERN IRELAND: Part III. Reservoir potential of the Permo-Triassic

Thick Permo-Triassic sandstones occur in two basins in Northern Ireland. The sandstones are fluvio-deltaic, including an oolitic facies, and are interbedded with mudrocks. They exhibit petrographic features which are typical of red beds and are widely found in the Permo-Triassic elsewhere in the British Isles. The predominant cements are haematite, potassium feldspar. illite and carbonates. Gypsum, anhydrite and dolomite cements occur in the regions of deepest burial. which represent the basin centres. There was widespread leaching of carbonate/sulphate cements, but calcite is preserved in the oolitic facies and below the sub-Cretaceous (chalk) unconformity. The dissolution of cements and framework grains was due to leaching by meteoric fluids. Precipitation of kaolinite in secondary pores, and subsequent illitization, represent fluctuations in the meteoric hydraulic head. Deep boreholes exhibit sandstone porosities which indicate that there may be significant reservoir potential where adequate seals and traps are present.     

COMMENTS ON "GRAVITY OVERTURNS, EXTENSION, AND BASEMENT FAULT ACTIVATION"

Koyi (1991) has described physical modelling experiments on the initiation of salt diapirism. He also compares his results with the results of an investigation of salt tectonics in the northern part of the Norwegian-Danish Basin by Hospers et al. (1988).
Koyi's comments on this investigation are not altogether favourable. Below, I intend to show that Koyi's criticisms are not valid, as they stem from a combination of: (1) built-in features present in his models which limit their applicability; and (2) an incomplete understanding of the structural setting in which salt diapirism was initiated in the northern part of the Norwegian-Danish Basin.     

Generalization of experimental data for forced fluid flow

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 12, pp. 12–13, December, 1992.     

A cooling process for an NaA type zeolite used in systems to purify argon of oxygen

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 16–17, November, 1992.     

Evaporators with hydrophobic heat-transfer agents

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 10, pp. 8–10, October, 1992.     

The journal Khimicheskoe i Neftyanoe Mashinostroenie is 60 years old

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 7, pp. 1–2, July, 1992.