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Some bis-(aryl/alkyl)thiuram disulphides, bis-(aryl)xanthogens and (aryl/alkyl)dithiocarbamates were synthesized and their extreme pressure (EP) and anti-wear (AW) properties evaluated using a Seta-Shell four-ball lubricant testing machine. Bis-(phenyl)xanthogen, bis-(ethanol)thiuram disulphide, bis-(diethanol)thiuram disulphide, bis-(naphthyl)thiuram disulphide and N,N-diethanol dithiocarbamate were found to be efficient EP additives showing a welding load in the range 315–500 kgf. The coefficient of friction and mean specific pressure were evaluated and their variation with load in the case of different additives explained. No additive was found to posses efficient anti-wear property. more...

Electron micrographs, dynamic light-scattering, and osmotic measurements have been performed on monolayered vesicles obtained from two bolaform amphiphiles of recent synthesis. Monolayered vesicles of bipolar lipids constitute an interesting model for primordial membranes. more...

Adsorption of Sr++ ions on copper metal surfaces has been studied by the tracer technique. The strontium nitrate solutions of different concentrations were labelled with90Sr and the copper coupons of electrolytic quality were kept immersed in these solutions for different intervals of time. The activity of both the faces of the coupons were measured with a GM counter after washing and drying the coupons. Results have been obtained on the amount of adsorption as a function of time, concentration of strontium nitrate solution and temperature. The data have been found to be in accordance with the Freundlich adsorption isotherm equation. Interpretation of the data in the light of the findings of other authors in similar systems has been made. more...

Transport phases of four metals of geochemical and water quality importance were investigated in rivers around Jamshedpur. The metals iron, manganese, zinc and copper were partitioned into dissolved, adsorbed and or ion exchangeable, solid organic, oxide coating and crystalline phases applying filtration for the dissolved phase and a chemical fractionation scheme for the particulates. Iron and copper were transported mainly in the particulate phases at all sites, while manganese and zinc were found in the dissolved phase up to a hundred percent depending on the pH of water sample and pollution at the site concerned. Except copper more than 75 percent of all other three metals occurred in transport modes thought to be available to aqueous and biotic interactions. Copper was in available phases from 50 to 70 percent. The significance of metal partitioning as a factor in controlling metal availability and toxicity to biota is discussed. more...

Data of McCormick, Goodstein, and Dash, and Stewart and Dash, for heat capacities of3He and4He films on Ar-plated copper in the submonolayer region have been analyzed on the basis of a model of a long-range variation of adsorption potential. This variation allows the adatoms to form small islands on the surface. The total heat capacity of the film is the sum of two contributions, one a Fermi-like contribution due to surface heterogeneity, and the other a two-dimensional Debye-like contribution due to molecular vibrations. The data are roughly consistent with a Debye temperature of 32K for all the4He data and 38 K for the3He data. The role of surface heterogeneity in the heat capacity of films is briefly discussed. more...

The high‐coverage isotherms of Lando and Slutsky for neopentane and tetramethyl silane on gold films are analysed on the basis of a slab model for adsorbed layers. It is possible to fit the data to an inverse cube law for surface energy if a structure relaxation term, as proposed by Adamson and Ling, is introduced. The cube law coefficients so obtained are approximately an order of magnitude larger than the theoretical values. more...