Grand canonical Monte Carlo and molecular dynamics simulations were applied to understand the molecular mechanism of ion and water transport in montmorillonite clays as a function of relative humidity (RH). The variation of basal spacings of montmorillonite as a function of RH predicted based on the swelling free energy profiles was consistent with X-ray data. The hydration of the montmorillonite shows the following well-known order: Mg 2+ > Ca 2+ > Sr 2+ > Li + > Na + > K +. The relative contribution of water on external surfaces only becomes significant close to the saturation pressure. However, this behavior for K-montmorillonite starts to occur well below the saturation pressure due to the clay-swelling inhibition by potassium ions. The diffusion of water and ions generally increases with RH in all samples. However, for samples with weakly hydrated ions, the water mobility in thin films adsorbed on external basal surfaces of clay can be higher than that in the water-saturated mesopores. For a given RH, mobility of interlayer species is typically lower than that from the external surfaces. The results of the simulations were applied to interpret recent laboratory measurements of ion mobility with changing RH. We also assess the effect of layer charge distribution on such sorption and diffusion processes.

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The failure of axonal regeneration after spinal cord injury (SCI) results in permanent loss of sensorimotor function. The persistent presence of scar tissue, mainly fibrotic scar and astrocytic scar, is a critical cause of axonal regeneration failure and is widely accepted as a treatment target for SCI. Astrocytic scar has been widely investigated, while fibrotic scar has received less attention. Here, we review recent advances in fibrotic scar formation and its crosstalk with other main cellular components in the injured core after SCI, as well as its cellular origin, function, and mechanism. This study is expected to provide an important basis and novel insights into fibrotic scar as a treatment target for SCI.

With conventional reservoirs being depleted, unconventional reservoirs play a significant role in worldwide energy supply. Even though the exploitation of unconventional resources has achieved unprecedentedly great success, flow mechanisms and the underneath phase behavior are not clearly illustrated. Recent studies indicate that the constant moles, pressure and temperature in many cases. We develop evolution equations for moles and volume using the laws of thermodynamics and Onsager's principle. A thermodynamically stable numerical algorithm is constructed, which is the extension of our previous work, by introducing a generalized Onsager coefficient matrix. The new algorithm exhibits better performance in efficiency and accuracy by simultaneously solving the evolutionary equations. At the equilibrium state, the pressure inequality resulting from the capillary pressure is spontaneously satisfied. In addition, by properly selecting the initial approximation for phase equilibrium calculations, we obtain a physically meaningful transition process with uniform phase identification. A number of numerical examples is presented to demonstrate the robust performance of the proposed model. It is found that capillary pressure affects phase composition and distribution. The bubble point pressure is suppressed under capillary effect, while the dew point pressure exhibits complex behavior: increasing in the upper branch and decreasing in the lower branch of the dew point curve. The unremarkable saturation change may attribute to the volume variation less sensitive than the pressure variation when the phase composition changes. In the limit of zero capillarity, our simulation results are consistent with the conventional isothermal-isochoric flash calculation.

Computer Methods in Applied Mechanics and Engineering Rights NOTICE: this is the author's version of a work that was accepted for publication in Computer Methods in Applied Mechanics and Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Computer Methods in Applied Mechanics and Engineering, [, , (2017-11-10)]