ROLE OF CLAYS IN THE ENHANCED RECOVERY OF PETROLEUM FROM SOME CALIFORNIA SANDS.

This study evaluates the type and amounts of clays and clay minerals present in typical oil-producing formations that may be candidates for application of EOR methods. After identification of the clay minerals present, tests are run on the extracted clay fractions to determine cation-exchange capacities (CEC's), surface areas, and chemical-loss characteristics. Flood tests are run on core samples to evaluate the magnitude of chemical loss and to note the change in flow characteristics while different fluids, which might be used in EOR operations, are flowed through the core. This background material is used to test predictive equations developed for screening reservoirs for EOR applications and for optimizing process variables. Techniques to counter the effects of rock/fluid interactions are considered

Pore-level investigation of foam/oil interactions in porous media

Direct visual studies of foam flow in etched-glass micromodels containing residual oil demonstrate that foam decays as a result of breakage of pseudoemulsion films. Foam films collapse whenever nearby thin aqueous films separating gas bubbles and oil rupture. Consequently, surfactant formulation for foam insensitivity to oil in porous media should be based on stabilizing pseudoemulsion films

Mass-transport resistances of acid and alkaline ionomer layers: A microelectrode study part 1 - Microelectrode development

The use of microelectrodes to study localized mass-transport phenomena in fuel-cell catalyst layers is an increasingly valuable tool. However, existing microelectrode cells have been used in static, equilibrated environment modes with poorly controlled interfaces. In this work, we present a microelectrode cell design that expands the experimental space addressable by microelectrodes to include mechanical pressure, gas flow and ionomer medium, and experimental throughput. The feasibility of the design is examined for fuel-cell reactions, with oxygen reduction currents independent of mechanical pressure and gas flowrate. Finally, cell equilibration time and IR drop across the electrolyte are estimated. The new cell design is robust and provides a consistent base from which to perform more complicated studies examining mass-transport properties of ionomers and/or the electrochemical reaction kinetics of hydrogen oxidation and oxygen reduction

110th Anniversary: Theory of Activity Coefficients for Lithium Salts in Aqueous and Nonaqueous Solvents and in Solvent Mixtures

On the basis of work by Bernard and Blum [Bernard, O.; Blum, L. Binding Mean Spherical Approximation for Pairing Ions: An Exponential Approximation and Thermodynamics. J. Chem. Phys. 1996, 104, 4746-4754], Barthel et al. [Barthel, J.; Krienke, H.; Holovko, M.; Kapko, V.; Protsykevich, I. The Application of the Associative Mean Spherical Approximation in the Theory of Nonaqueous Electrolyte Solutions. Condens. Matter Phys. 2000, 3, 23], and Simonin et al. [Simonin, J.-P.; Bernard, O.; Blum, L. Real Ionic Solutions in the Mean Spherical Approximation. 3. Osmotic and Activity Coefficients for Associating Electrolytes in the Primitive Model. J. Phys. Chem. B 1998, 102, 4411-4417], this work presents and validates a molecular-thermodynamic model for lithium salt activity coefficients in aqueous and nonaqueous single- and mixed-solvent systems. The Binding Mean Spherical Approximation gives electrolyte activity due to long-range electrostatic forces, short-range hard-sphere repulsion, and ion-pair formation. The theory shows good agreement with measured salt activities up to 3 molar in aqueous and nonaqueous solvents using a solvent-dependent, concentration-independent, center-to-center distance of closest approach between ions as the single fitting parameter for each electrolyte system. For mixed-solvent electrolytes, the local solvation environment around the ions dictates short-range interactions. To account for preferential ion solvation in a mixed solvent, the center-to-center distance is obtained from Wang and co-workers' Dipolar Self-Consistent-Field Theory [Nakamura, I.; Shi, A.-C.; Wang, Z.-G. Ion Solvation in Liquid Mixtures: Effects of Solvent Reorganization. Phys. Rev. Lett. 2012, 109, 257802]. For a particular salt in a binary solvent mixture at fixed temperature, the model predicts salt activity coefficients using only the fitted single-solvent distances-of-closest approach

ENHANCED RECOVERY WITH MOBILITY AND REACTIVE TENSION AGENTS.

To establish and improve recovery efficiencies of acidic crude oils with alkaline agents this work includes studies on displacement dynamics and modeling, chemical transport, and emulsion flow and displacement. An equilibrium chemical displacement model is presented. The unique feature of this theory is that the chemistry of the acid hydrolysis to produce in-situ surfactants is rigorously included. Calculations with the model reveal delayed and reduced tertiary oil recovery for adverse mobility ratios, and the critical importance of quantifying alkali rock interactions. Design of alkaline floods based only on properties of the fluid phases, such as interfacial tension, interfacial viscosity, or emulsion stability, can be obviated by the paramount role of rock-chemical reactions

Ice crystallization during cold-start of a proton-exchange-membrane fuel cell

Under subfreezing conditions, ice forms in the gas-diffusion (GDL) and catalyst layers (CL) of proton-exchange-membrane fuel cells (PEMFCs), drastically reducing cell performance. Although a number of strategies exist to prevent ice formation, there is little fundamental understanding of ice-crystallization mechanisms and kinetics within PEMFC components. We incorporate recently developed ice-crystallization kinetic expressions (1-3) within the CL and GDL of a simplified 1-D transient PEMFC cold-start model. To investigate the importance of ice-crystallization kinetics, we compare liquid-water and ice saturations, and cell-failure time predicted using our kinetic rate expression relative to that predicted using a thermodynamic-based approach. We identify conditions under which ice-crystallization kinetics is critical and elucidate the impact of freezing kinetics on low-temperature PEMFC operation. © The Electrochemical Society

Seasonal Variation in Vitamin D3 Levels Is Paralleled by Changes in the Peripheral Blood Human T Cell Compartment

It is well-recognized that vitamin D3 has immune-modulatory properties and that the variation in ultraviolet (UV) exposure affects vitamin D3 status. Here, we investigated if and to what extent seasonality of vitamin D3 levels are associated with changes in T cell numbers and phenotypes. Every three months during the course of the entire year, human PBMC and whole blood from 15 healthy subjects were sampled and analyzed using flow cytometry. We observed that elevated serum 25(OH)D3 and 1,25(OH)2D3 levels in summer were associated with a higher number of peripheral CD4+ and CD8+ T cells. In addition, an increase in naïve CD4+CD45RA+ T cells with a reciprocal drop in memory CD4+CD45RO+ T cells was observed. The increase in CD4+CD45RA+ T cell count was a result of heightened proliferative capacity rather than recent thymic emigration of T cells. The percentage of Treg dropped in summer, but not the absolute Treg numbers. Notably, in the Treg population, the levels of forkhead box protein 3 (Foxp3) expression were increased in summer. Skin, gut and lymphoid tissue homing potential was increased during summer as well, exemplified by increased CCR4, CCR6, CLA, CCR9 and CCR7 levels. Also, in summer, CD4+ and CD8+ T cells revealed a reduced capacity to produce pro-inflammatory cytokines. In conclusion, seasonal variation in vitamin D3 status in vivo throughout the year is associated with changes in the human peripheral T cell compartment and may as such explain some of the seasonal variation in immune status which has been observed previously. Given that the current observations are limited to healthy adult males, larger population-based studies would be useful to validate these findings

Quantitative trait loci mapping reveals candidate pathways regulating cell cycle duration in Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>Elevated parasite biomass in the human red blood cells can lead to increased malaria morbidity. The genes and mechanisms regulating growth and development of <it>Plasmodium </it><it>falciparum </it>through its erythrocytic cycle are not well understood. We previously showed that strains HB3 and Dd2 diverge in their proliferation rates, and here use quantitative trait loci mapping in 34 progeny from a cross between these parent clones along with integrative bioinformatics to identify genetic loci and candidate genes that control divergences in cell cycle duration.</p> <p>Results</p> <p>Genetic mapping of cell cycle duration revealed a four-locus genetic model, including a major genetic effect on chromosome 12, which accounts for 75% of the inherited phenotype variation. These QTL span 165 genes, the majority of which have no predicted function based on homology. We present a method to systematically prioritize candidate genes using the extensive sequence and transcriptional information available for the parent lines. Putative functions were assigned to the prioritized genes based on protein interaction networks and expression eQTL from our earlier study. DNA metabolism or antigenic variation functional categories were enriched among our prioritized candidate genes. Genes were then analyzed to determine if they interact with cyclins or other proteins known to be involved in the regulation of cell cycle.</p> <p>Conclusions</p> <p>We show that the divergent proliferation rate between a drug resistant and drug sensitive parent clone is under genetic regulation and is segregating as a complex trait in 34 progeny. We map a major locus along with additional secondary effects, and use the wealth of genome data to identify key candidate genes. Of particular interest are a nucleosome assembly protein (PFL0185c), a Zinc finger transcription factor (PFL0465c) both on chromosome 12 and a ribosomal protein L7Ae-related on chromosome 4 (PFD0960c).</p

Using shared goal setting to improve access and equity : a mixed methods study of the Good Goals intervention in children's occupational therapy

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