IYTE GCRIS Database (Izmir Institute of Technology)
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Body Waves in Poroelastic Media Saturated by Two Immiscible Fluids
No full textA study of body waves in elastic porous media saturated by two immiscible Newtonian fluids is presented. We analytically show the existence of three compressional waves and one rotational wave in an infinite porous medium. The first and second compressional waves are analogous to the fast and slow compressional waves in Biot's theory. The third compressional wave is associated with the pressure difference between the fluid phases and dependent on the slope of capillary pressure-saturation relation. Effect of a second fluid phase on the fast and slow waves is numerically investigated for Massillon sandstone saturated by air and water phases. A peak in the attenuation of the first and second compressional waves is observed at high water saturations. Both the first and second compressional waves exhibit a drop in the phase velocity in the presence of air. The results are compared with the experimental data available in the literature. Although the phase velocity of the first compressional and rotational waves are well predicted by the theory, there is a discrepancy between the experimental and theoretical values of attenuation coefficients. The causes of discrepancy are explained based on experimental observations of other researchers
Prolactin Receptor Gene Expression in Rat Splenocytes and Thymocytes From Birth To Adulthood
No full textIn vivo and in vitro studies have indicated that the anterior pituitary hormone prolactin (PRL) is an immunoregulator and functions in the development of the neonatal immune system. In this study, prolactin receptor (PRL-R) expression from birth to adulthood as well as the effect of milk ingestion on the PRL-R expression were examined in splenocytes and thymocytes of neonatal rats. Three approaches were taken to measure PRL-R expression: (i) polymerase chain reaction (RT-PCR); (ii) antibody to PRL-R and Western blotting; (iii) antibody to PRL-R and flow cytometry. RT-PCR analysis revealed the short and long form of PRL-R mRNA in both spleen and thymus at every age tested. However, the long form of PRL-R mRNA was always more abundant than that of the short form. In addition, antipeptide antibody against the long form of PRL-R recognized 84 and 42 kD proteins in the spleen, but only the 84 kD protein in the thymus. A monoclonal antibody U6 recognized 38 and 40 kD proteins in both the spleen and thymus. Although the mRNA level of PRL-R was relatively low at birth and increased with age in both the spleen and thymus, the levels of protein bands detected with both antibodies correlated with development in the spleen; whereas the levels remained steady in the thymus. Therefore, we concluded that the expression of PRL-R at the protein level is developmentally regulated in the spleen but not in the thymus. Finally, milk ingestion in the first seven hours decreased the percentage of cells expressing cell surface PRL-R, suggesting that milk-borne PRL may have a direct effect on lymphocytes
Consolidation of Elastic Porous Media Saturated by Two Immiscible Fluids
No full textA theory is presented to simulate the consolidation of elastic porous media saturated by two immiscible Newtonian fluids. The macroscopic equations, including mass and momentum balance equations and constitutive relations, are obtained by volume averaging the microscale equations. The theory is based on the small deformation assumption. In the microscale, the grains are assumed to be linearly elastic and the fluids are Newtonian. The bulk and shear moduli of the solid matrix are introduced to obtain the macroscopic constitutive equations. Momentum transfer terms are expressed in terms of intrinsic and relative permeabilities assuming the validity of Darcy's law. In one dimension, the governing equations reduce to two coupled diffusion equations in terms of the pore pressures of the fluid phases. An analytical solution is obtained for a column with a fixed impervious base and a free drainage surface. Results are presented for cases of practical interest, i.e., columns saturated by oil-water and air-water phases. Results indicate that the presence of a second fluid phase affects pore water pressure and total settlement
Wave Propagation in Fractured Porous Media
No full textA theory of wave propagation in fractured porous media is presented based on the double-porosity concept. The macroscopic constitutive relations and mass and momentum balance equations are obtained by volume averaging the microscale balance and constitutive equations and assuming small deformations. In microscale, the grains are assumed to be linearly elastic and the fluids are Newtonian. Momentum transfer terms are expressed in terms of intrinsic and relative permeabilities assuming the validity of Darcy's law in fractured porous media. The macroscopic constitutive relations of elastic porous media saturated by one or two fluids and saturated fractured porous media can be obtained from the constitutive relations developed in the paper. In the simplest case, the final set of governing equations reduce to Biot's equations containing the same parameters as of Biot and Willi
Adsorption Equilibrium and Dynamics of Lactase/Cm-sephadex System
No full textPartitioning behaviour and adsorption isotherms of lactase/CM-Sephadex system at equilibrium were investigated together with the adsorption kinetics in this study. Maximum adsorption was obtained at the pH values between 5.5–6.0. Adsorption isotherm was a close fit to the Langmuir model
Modeling Deficit Irrigation in Alfalfa Production
No full textA conceptual agronomic model EPIC was extended to consider the effects of salinity in alfalfa production under optimal and water stress irrigation conditions. The extended model was calibrated and validated with observed lysimeter data. The model parameters that affected alfalfa yield and soil salinity the most were wilting point, field capacity, hydraulic conductivity, nitrate concentration, biomass energy ratio, seeding rate, average soil salinity EC e at which crop yield is reduced by 50% ( EC50 ), and initial soil gypsum concentration. The calibrated and validated model was then applied to an alfalfa deficit irrigation study. The four irrigation treatments included optimum check, minimum stress, short stress, and long stress, each of which produced differential alfalfa yields. The purpose of summer deficit irrigation was to ascertain how much agricultural water at what cost could be made available for urban water uses during water shortfalls. The results of model simulation were found to be satisfactory under all irrigation treatments though the model slightly overestimated the yields and underestimated the soil EC e at the end of short and long stress treatments. An economic component is included to determine the appropriate compensation for farmers undergoing a range of deficit irrigations
Effective Stress Principle for Saturated Fractured Porous Media
No full textAn effective stress principle for saturated fractured porous media is proposed based On the double-porosity representation. Both the solid grains and the fractured porous medium are assumed to be linearly elastic materials. The derivation employs volume averaging technique to obtain macroscopic scale expressions. Two parameters, the bulk modulus of the fractured medium and bulk modulus of the porous matrix, are introduced in the formulation. The final expression reduces to the one obtained by Blot and Willis [1957], Skempton [1960], Nur and Byeerle [1971], and Verruijt [1984] when the volume fraction of the fractures vanishes, that is, for a nonfractured porous medium
Electrolysis of Mgcl2 With a Top Inserted Anode and an Mg-Pb Cathode
No full textHigh energy consumption in the production of magnesium by molten salt electrolysis is mainly due to the recombination of magnesium and chlorine. The large interelectrode distance used, in conventional techniques, to reduce the extent of ‘back reaction’, results in a significant potential drop. A laboratory cell that enables the operation with smaller interelectrode distance and easy separation of electrode products has been used to study electrolytic magnesium production. The cell features a top inserted graphite anode and a Mg-Pb alloy cathode at the bottom. Current efficiency and power consumption were determined at 690° C using a current density of 0.48 A cm−2. Experiments were performed to study the effects of MgCl2 concentration and anode-cathode distance (a.c.d.) on cell operation. Results indicated that an electrolyte containing 20% MgCl2 (equiweight NaCl:KCl and 1 % NaF) with a 3 cm a.c.d. reduced the cell voltage to 3.72 V. This value corresponds to an energy consumption of 11.3 kWh kg−1 including the refining of Mg-Pb alloy produced at the cathode. This cell performance is more energy efficient compared to conventional magnesium cells