Volume 37, Issue 1

Abstract. The extension of our previous paper [Can. J. Phys., 88 (2010), 501–511] has been made for an inhomogeneous charged rarefied gas mixture (two components plasma) instead of a single electron gas. In the present work, the kinetic and the irreversible thermodynamic properties of the plasma are presented from the molecular point of view. Our study is based on the solution of the BGK (Bhatnager–Gross–Krook) model of the Boltzmann kinetic equation together with the Maxwell's equations for both positive ions and electrons in the vicinity of a moving rigid plane. The fundamental aim of this investigation is to illustrate the mutual effects caused by collisions on the distribution functions. The distinction and comparisons between the perturbed and the equilibrium velocity distribution functions are illustrated for both electrons and ions. The ratios between the different contributions of the internal energy changes are predicted via the Gibbs's equation for both diamagnetic and paramagnetic plasmas. The results are applied to a typical model of laboratory Argon plasma.

Abstract. In this paper a model for dielectric material in the formalism of Kluitenberg's theory on dielectric relaxation phenomena is proposed. The aim of the paper is to suggest a thermodynamic model with internal variable for dielectric isotropic material; in particular, by introducing the reciprocal complex dielectric susceptibility, expressions will be proposed for the dielectric storage modulus and dielectric loss modulus in cases of low and high frequencies. Finally, an expression for the reciprocal of complex susceptibility allows us to compare the results obtained with experimental data in the case of low frequencies.

Abstract. A microscopic formulation of the definition of both the heat flux and the viscous stress tensor is proposed in the framework of kinetic theory for relativistic gases emphasizing the physical nature of such fluxes. A Lorentz transformation is introduced as the link between the laboratory and the local comoving frames and thus between molecular and chaotic velocities. With such a transformation, the dissipative effects can be identified as the averages of the chaotic kinetic energy and momentum fluxes out of equilibrium, respectively. Within this framework, a kinetic foundation of the ensuing transport equations for the relativistic gas is achieved. To our knowledge, this result is completely novel.

Abstract. Our previous approach on thermodiffusion modeling of dilute polymer solutions is extended to dilute DNA solutions. The model is based on linear non-equilibrium thermodynamics and the concept of Eyring's activation energy of viscous flow to estimate the Soret coefficient in thermophoresis of macromolecules that are not in liquid phase. The net heat of transport of single- and double-stranded DNA molecules, which are in solid state, are replaced by the activation energy of viscous flow of liquid alkanes with comparable molecular weights. The proposed formula is tested against available experimental data and qualitative agreement is observed. For double-stranded DNA molecules, the experimental data are scattered and the model can qualitatively predict the data, whereas for single-stranded DNA experiments in the infinite dilution model, for which the model is prescribed, a very good agreement is observed.

Abstract. The transport of NaCl and ethanol through the microbial cellulose membrane was used as a generator of layers with density gradients, parallel to gravity vector. Changes in NaCl concentrations connected with density gradients in these layers were monitored by means of Ag|AgCl electrodes dipped directly into aqueous NaCl solutions with or without ethanol. The parameters used in this article and characterizing diffusive or diffusive–convective processes in layers are the ratio of NaCl concentrations at electrode surfaces () calculated for voltage which was measured 6 h after rebuilding of layers with density gradients, and time of appearance of hydrodynamic instabilities in the membrane system. The is the nonlinear function of initial ratio of NaCl on the membrane (), with maximum concentration at initial moment dependent on ethanol and configuration of the membrane system. The time of appearance of hydrodynamic instabilities in layers with density gradients parallel and directed opposite to the gravity vector depends on , ethanol concentration, and configuration of the membrane system. Besides, for aqueous NaCl solutions, critical values of density gradients and thicknesses of layers needed for the appearance of hydrodynamic instabilities were calculated and presented as functions of .

Abstract. The thermodiffusion model of Firoozabadi and co-workers as well as two correlations from the literature have been applied to five mixtures ofn-decane/isobutylbenzene/tetralin at three different temperatures. All three approaches predict the separation of n-decane and tetralin to the hot and the cold side, respectively. In three of these mixtures there is a disagreement between the Firoozabadi model and the two correlations on the direction of separation of isobutylbenzene, the component with an intermediate molecular weight. Hence, these mixtures have been identified as important mixtures from the experimental point of view. Finally, from the results it is proposed that the planned experiments be performed at 318 K and 1 atm where thermodiffusion is dominant.