Gas transport in partially-saturated sand packs

Understanding gas transport in porous media and its mechanism has broad applications in various research areas, such as carbon sequestration in deep saline aquifers and gas explorations in reservoir rocks. Gas transport is mainly controlled by pore space geometrical and morphological characteristics. In this study, we apply a physically-based model developed using concepts from percolation theory (PT) and the effective-medium approximation (EMA) to better understand diffusion and permeability of gas in packings of angular and rounded sand grains as well as glass beads. Two average sizes of grain i.e., 0.3 and 0.5 mm were used to pack sands in a column of 6 cm height and 4.9 cm diameter so that the total porosity of all packs was near 0.4. Water content, gas-filled porosity (also known as gas content), gas diffusion, and gas permeability were measured at different capillary pressures. The X-ray computed tomography method and the 3DMA-Rock software package were applied to determine the average pore coordination number z. Results showed that both saturation-dependent diffusion and permeability of gas showed almost linear behavior at higher gas-filled porosities, while deviated substantially from linear scaling at lower gas saturations. Comparing the theory with the diffusion and permeability experiments showed that the determined value of z ranged between 2.8 and 5.3, not greatly different from X-ray computed tomography results. The obtained results clearly indicate that the effect of the pore-throat size distribution on gas diffusion and permeability was minimal in these sand and glass bead packs

Diphosphorylation of myosin light chain in smooth muscle cells in culture Possible involvement of protein kinase C

AbstractProstaglandin (PG) F2α (30 μM) stimulated both monophosphorylation and diphosphorylation of myosin light chain (MLC) in a smooth muscle cell line (SM-3). The diphosphorylation was significantly decreased by treatment with the protein kinase C inhibitor staurosporine (30 nM, 30 min) from 20.1% of total MLC to 4.5%. The protein kinase C down-regulation treatment of SM-3 cells with phorbol dibutyrate suppressed to 8.7% the MLC diphosphorylation activity in the SM-3 cells. This down-regulation treatment had little effect on the monophosphorylation. We propose that the MLC diphosphorylation in PGF2α-stimulated SM-3 cells in culture may be regulated through mechanisms sensitive to protein kinase C

Temperature effects on geotechnical properties of kaolin clay: Simultaneous measurements of consolidation characteristics, shear stiffness, and permeability using a modified oedometer

The increased worldwide use of shallow geothermal energy systems including ground source heat pumps (GSHPs) have given concerns of possible temperature effects on soil geotechnical properties. In this study, the effects of temperature on mechanical characteristics such as consolidation settlement, shear stiffness, and permeability of kaolin clay were investigated. A modified oedometer apparatus which allows the simultaneous measurements of consolidation settlement, shear wave velocity, and hydraulic conductivity was developed and used. Consolidation tests on preconsolidated kaolin samples (two sample sizes: ϕ 6 cm x H 10 cm and ϕ 6 cm x H 2 cm) were performed under sequentially increasing consolidation pressures at three different temperatures (5 °C, 15 °C, and 40 °C). Larger apparent preconsolidation pressure, Pac, was seen at higher temperature (40 °C) for both sample sizes, but only for samples having relatively high initial void ratios between 1.53 and 1.62. Relatively higher shear modulus as a function of void ratio was observed for samples at higher temperature, suggesting that changes in fabric structure (likely caused by enhanced inter-particle forces between clay particles at higher temperature) resulted in the increased shear stiffness and, thus, higher Pac at 40 °C. Oppositely, temperature effects on theManuscript received February 5, 2013. This work was partly funded by a grant from the Research Management Bureau, Saitama University, the grant-in-Aid for Scientific Research of Japan Society for the Promotion of Science (JSPS) (No.22860012), and a JSPS bilateral research project. This work was also partially supported by a CREST project, a research grant from the Japan Science and Technology Agency (JST).E. E. Mon is with Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura ku, Saitama, 338-8570, Japan. (phone/fax: (+81) 48-858-3116; e-mail: [email protected]).S. Hamamoto, is with Graduate School of Science and Engineering, and Institute for Environmental Science and Technology, Saitama University, 255 Shimo-okubo, Sakura ku, Saitama, 338-8570, Japan. (e-mail: [email protected])K. Kawamoto is with Graduate School of Science and Engineering, and Institute for Environmental Science and Technology, Saitama University, 255 Shimo-okubo, Sakura ku, Saitama, 338-8570, Japan. (e-mail: [email protected]).T. Komatsu is with Graduate School of Science and Engineering, and Institute for Environmental Science and Technology, Saitama University, 255 Shimo-okubo, Sakura ku, Saitama, 338-8570, Japan. (e-mail: [email protected]).P. Mødrup is with Department of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, Denmark. (e-mail: [email protected]). permeability of kaolin clay were not significant within the studied temperature range between 5 °C and 40 °C

Geotechnical Properties of Kanto Alluvial Soils based on Geochemical Survey

Chemical properties of pore water in soils have a great influence on interparticle bonding among clayey particles and, as a result, not only on their soil structure but also on their geotechnical properties. In this study, we analyzed ionic compositions in pore water extracted from alluvial soils deposited under different sedimentary environments in Kanto lowland area, Japan, and investigated the effect of the chemical compositions of pore water on the geotechnical properties such as compressibility and sensitivity. The following results were obtained: The ion concentrations of pore water measured by different extraction methods showed that the concentration of Na+ by the dilution method was higher than that by the centrifugation method, while the concentrations of Ca2+, Cl- and SO42- by the dilution method are significantly smaller than those by centrifugation method. The centrifugation method was recommended for evaluating geochemistry of the soils since the rotation speeds in the centrifugation method did not significantly affect the pore-water compositions. The geotechnical properties were highly related to the ion concentrations of pore water. Higher compression index and sensitivity were observed for the alluvial soils with higher monovalent/divalent ion ratio. In addition, more strong dependency of monovalent/divalent ion ratio on geotechnical properties was obtained for the alluvial soils with plasticity index larger than 30