Synergism of non-ionic and anionic surfactants in a binary solution.

Adsorption at the gas —air interface and micelle formation in binary solutions of ethoxylated alkyl phenol (Neonol AF 9-10) and sodium oleate have been studied. The Rubin and Rosen equations were used to determine the interaction parameters and the composition of mixed micelles and adsorption layers depending on the initial solution composition. The authors have found out that the micelles and the adsorption layer at the interface are enriched in a non-ionic component. The maximum synergistic effect during micelle formation was found for solutions containing 20–30 % molar of reagent Neonol AF 9-10, and during adsorption —20 and 50 %.

Temperature modes of the contactor contacts during the test for the limiting breaking capacity

The processes of electric arc quenching of an electromagnetic contactor during testing for ultimate breaking capacity are considered. The conditions for facilitating the successful arc quenching when turning off the limiting currents are shown: by reducing the phase shift between current and voltage, by reducing the amplitude of the restriking and recovery voltages. The processes of anode heating during arcing (heat saturation mode), after the change of polarity and transition of the current through zero, processes on the cathode in the temperature equalization mode are considered. The mathematical models of cathode thermal processes adressed the heat fluxes of the ionic component and evaporation. The mathematical models of anode thermal processes in the temperature equalization mode took into account the heat fluxes of the ionic component, thermionic emission, and evaporation. The calculations were carried out for the averaged values of thermophysical coefficients for copper, since the arc base moves from the contacts to the contact holders, which are made of copper or its alloys. The calculation results showed that the used mathematical models of thermal processes are appropriate both for the cathode and for the anode. This was confirmed by the results of previously performed and published experimental and theoretical studies of thermal processes at the switching contacts of electrical devices.

Contribution to the Determination of In Vivo Mechanical Characteristics of Human Skin by Indentation Test

This paper proposes a triphasic model of intact skin in vivo based on a general phenomenological thermohydromechanical and physicochemical (THMPC) approach of heterogeneous media. The skin is seen here as a deforming stratified medium composed of four layers and made out of different fluid-saturated materials which contain also an ionic component. All the layers are treated as linear, isotropic materials described by their own behaviour law. The numerical simulations of in vivo indentation test performed on human skin are given. The numerical results correlate reasonably well with the typical observations of indented human skin. The discussion shows the versatility of this approach to obtain a better understanding on the mechanical behaviour of human skin layers separately.