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In the present study, the ionic transport and selectivity of electrokinetically-driven flow of power-law fluids in a long pH-regulated rectangular nanochannel are analyzed. The electrical potential and momentum equations are numerically solved through a finite difference procedure for a non-uniform grid. Non-linear Poisson-Boltzmann equation along with the association/dissociation reactions on the surface is considered. In addition, numerical simulations with the finite element method in 3D space are performed to compare the results with those obtained from 2D analysis. Moreover, an analytical solution under Debye-H\"uckel approximation for the limiting case of a slit nanochannel is derived and its results are compared with those obtained from numerical simulations. It is shown that the channel aspect ratio can influence all the physicochemical parameters. It is observed that the mean velocity and the convective ionic conductance are strong descending functions of the flow behavior index. By investigating the non-Newtonian fluid behavior effect, it is revealed that its impact on the ionic conductance becomes significant at high values of the solution pH and its variation can alter the anionic transport direction inside the nanochannel. Moreover, it is shown the flow behavior index can strongly influence the ion selectivity of the nanochannel and its variation can be used to let the selectivity go through its maximum as a function of pH., Comment: 51 pages, 14 figures

Evaporation from soil and other porous media constitutes a significant source of water loss affecting global water balance and energy exchange between land and atmosphere. The presence of a shallow water table can lead to sustained water loss that is dependent on porous media hydraulic properties and water table depth among other factors. In this paper, an exact analytical solution to steady state evaporation from porous media is developed using the Brooks-Corey hydraulic conductivity model. The solution is presented in terms of a set of infinite series. An advantage of this solution compared to previous derivations is that the infinite series can be very closely approximated using a closed-form solution (i.e., excluding integrals or series). The novel solution shows excellent agreement with the exact solution for a broad range of soil texture from sand to clay. The applicability of the solution to predict the location of the drying front was also verified using experimental data taken from the literature. The solution may be used for directly modeling steady state evaporation or for inverse determination of the Brooks-Corey hydraulic parameters.

11 figures, 5 tables.-- Supplementary information available.-- © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, In this study, a new method was developed for the characterization of the interface morphology in polymer/particle composites. This method, not limited to a specific polymer or particle, utilizes the gas permeability of the composites to determine the interfacial properties such as the type of polymer-particle interactions as well as the thickness and the transport properties of the interphase. Moreover, it can be employed to determine the size of the aggregates in the case of particle aggregation. The proposed method was evaluated by comparing its results with the findings of the small-angle X-ray scattering (SAXS) analysis for polyethersulfone (PES)-based composites containing pristine and fumed silica nanoparticles. Our method was also evaluated by analyzing the results of other studies obtained from the literature., B.Z. acknowledges the “Juan de la Cierva” Program (IJCI-2016-30776).