70 research outputs found

    Effects of viscous dissipation on miscible thermo-viscous fingering instability in porous media

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    The thermo-viscous fingering instability associated with miscible displacement through a porous medium is studied numerically, motivated by applications in upstream oil industries especially enhanced oil recovery (EOR) via wells using hot water flooding and steam flooding. The main innovative aspect of this study is the inclusion of the effects of viscous dissipation on thermal viscous fingering instability. An Arrhenius equation of state is employed for describing the dependency of viscosity on temperature. The normalized conservation equations are solved with the finite element computational fluid dynamics code, COMSOL (Version 5) in which glycerol is considered as the solute and water as the solvent and the two-phase Darcy model employed (which couples the study Darcy flow equation with the time-dependent convection-diffusion equation for the concentration). The progress of finger patterns is studied using concentration and temperature contours, transversely averaged profiles, mixing length and sweep efficiency. The sweep efficiency is a property widely used in industry to characterize how effective is displacement and it can be defined as the ratio of the volume of displaced fluid to the total volume of available fluid in a porous medium in the displacement process. The effects of Lewis number, Brinkman number and thermal lag coefficient on this instability are examined in detail. The results indicate that increasing viscous dissipation generates significant enhancement in the temperature and a marked reduction in viscosity especially in the displaced fluid (high viscous phase). Therefore, the mobility ratio is reduced, and the flow becomes more stable in the presence of viscous dissipation

    Linear stability analysis and CFD simulation of thermal viscous fingering instability in anisotropic porous media

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    The water or steam injection in oil fields is a usual method for enhanced oil recovery in petroleum engineering. The thermo-viscous fingering instability is one of the main problems with complex nature that decreases the efficiency of oil extraction. Actually, the oil wells are the porous medium with a level of anisotropy for permeability and diffusion. In this paper, the thermal viscous fingering instability in anisotropic media has been investigated using both linear stability analysis and CFD simulation. For stability analysis, the growth rate of disturbances is determined by solving quasi-steady state equations via shooting method. The CFD simulation is performed by solving the governing equations of heat and mass transfer using a spectral method. It is shown that the longitudinal direction permeability and the transverse direction dispersion have important effect on the instability. The value of thermal-lag coefficient and the Lewis number have opposite effects on the different types of displacements that are considered. For the case of sweeping the porous media via the cold fluid, increasing the Lewis number intensifies the level of flow instability

    Multiple forms of atypical rearrangements generating supernumerary derivative chromosome 15

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    <p>Abstract</p> <p>Background</p> <p>Maternally-derived duplications that include the imprinted region on the proximal long arm of chromosome 15 underlie a complex neurobehavioral disorder characterized by cognitive impairment, seizures and a substantial risk for autism spectrum disorders<abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. The duplications most often take the form of a supernumerary pseudodicentric derivative chromosome 15 [der(15)] that has been called inverted duplication 15 or isodicentric 15 [idic(15)], although interstitial rearrangements also occur. Similar to the deletions found in most cases of Angelman and Prader Willi syndrome, the duplications appear to be mediated by unequal homologous recombination involving low copy repeats (LCR) that are found clustered in the region. Five recurrent breakpoints have been described in most cases of segmental aneuploidy of chromosome 15q11-q13 and previous studies have shown that most idic(15) chromosomes arise through BP3:BP3 or BP4:BP5 recombination events.</p> <p>Results</p> <p>Here we describe four duplication chromosomes that show evidence of atypical recombination events that involve regions outside the common breakpoints. Additionally, in one patient with a mosaic complex der(15), we examined homologous pairing of chromosome 15q11-q13 alleles by FISH in a region of frontal cortex, which identified mosaicism in this tissue and also demonstrated pairing of the signals from the der(15) and the normal homologues.</p> <p>Conclusion</p> <p>Involvement of atypical BP in the generation of idic(15) chromosomes can lead to considerable structural heterogeneity.</p

    Analysis of Agricultural Production Cooperatives in Achieving Sustainable Development in Agriculture Sector

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    The objective of the present study was analysis of agricultural production cooperatives in achieving sustainable development in agriculture. The statistical population of the study consisted of active members of agricultural production cooperatives in Karaj city (N=1354). 168 individuals were selected using Cochran sampling formula. The main research instrument was a questionnaire that its validity was obtained by a panel of experts and its reliability was confirmed by Cronbach's alpha coefficient (α>0.7). The data were gathered at a given time in 2014. Data analysis was performed using the SPSSwin18. The results showed that components of the studied cooperatives do not have perfect knowledge regarding to sustainable development. Also, factor analysis classified the role of agricultural production cooperatives to reach sustainable development into some factors including improving the utilization system, soil conservation and restoration of the degraded agricultural lands, increasing income and economic ability of  producers, self-sufficiency and food security, enhancing the biological production and biodiversity, management of plant pests and diseases, and conservation and sustainable use of plant and animal genetic resources. Besides, obstacles of sustainable development in the agricultural sector were classified into the Socio – economic, infrastructure, natural resources – environmental and technological factors

    Blockade of dorsal hippocampal dopamine receptors inhibits state-dependent learning induced by cannabinoid receptor agonist in mice

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    To clarify the interaction between cannabinnoid CB1 receptors and the dopaminergic system in memory processes, the effects of dopamine receptor agents on the state-dependent learning induced by the non-selective CB1/CB2 receptor agonist, WIN55,212-2 have been investigated in mice. Animals implanted with unilateral cannula at the CA1 region of the dorsal hippocampus and microinjected with WIN55,212-2 and/or dopaminergic agents, were tested using a single-trial step-down passive avoidance task. Intra-CA1 microinjections of WIN55,212-2 (0.1-1μg/mouse) immediately after training, decreased the step-down latency, indicating an amnesic effect of the drug. The amnesia was reversed by pre-test administration of the drug, suggesting state-dependent learning by the cannabinoid. Pre-test microinjection of apomorphine, a D1/D2 dopamine receptor agonist (0.1-0.3μg/mouse) into the CA1 region reversed the amnesia induced by post-training WIN55,212-2 (1μg/mouse). Moreover, pre-test co-administration of apomorphine with an ineffective dose of WIN55,212-2 (0.01μg/mouse), showed a reversion of the impairment on retention performance. Pre-test administration of the same doses of apomorphine did not show any response by itself. Pre-test intra-CA1 administration of a D1 dopamine receptor antagonist, SCH23390 (0.05-0.3μg/mouse) or D2 dopamine receptor antagonist, sulpiride (0.125-0.5μg/mouse) inhibited the expression of WIN55,212-2-induced state-dependent learning. Pre-test microinjection of the same doses of SCH23390 or sulpiride had no effect on WIN55,212-2-induced amnesia. Moreover, single injection of SCH23390 (0.2 and 0.3μg/mouse) or sulpiride (0.125μg/mouse) decreased memory retrieval. The results suggest that the dorsal hippocampal dopaminergic system participates in the modulation of WIN55,212-2-induced state-dependent learning. © 2010 Elsevier Ireland Ltd and the Japan Neuroscience Society

    Recombinant Protein Vaccines Formulated with Enantio-Specific Cationic Lipid R-DOTAP Induce Protective Cellular and Antibody-Mediated Immune Responses in Mice

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    Adjuvants are essential components of subunit vaccines added to enhance immune responses to antigens through immunomodulation. Very few adjuvants have been approved for human use by regulatory agencies due to safety concerns. Current subunit vaccine adjuvants approved for human use are very effective in promoting humoral immune responses but are less effective at promoting T-cell immunity. In this study, we evaluated a novel pure enantio-specific cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (R-DOTAP) as an immunomodulator for subunit vaccines capable of inducing both humoral- and cellular-mediated immunity. Using recombinant protein antigens derived from SARS-CoV2 spike or novel computationally optimized broadly reactive influenza antigen (COBRA) proteins, we demonstrated that R-DOTAP nanoparticles promoted strong cellular- and antibody-mediated immune responses in both monovalent and bivalent vaccines. R-DOTAP-based vaccines induced antigen-specific and polyfunctional CD8+ and CD4+ effector T cells and memory T cells, respectively. Antibody responses induced by R-DOTAP showed a balanced Th1/Th2 type immunity, neutralizing activity and protection of mice from challenge with live SARS-CoV2 or influenza viruses. R-DOTAP also facilitated significant dose sparing of the vaccine antigens. These studies demonstrate that R-DOTAP is an excellent immune stimulator for the production of next-generation subunit vaccines containing multiple recombinant proteins

    Recombinant Protein Vaccines Formulated with Enantio-Specific Cationic Lipid R-DOTAP Induce Protective Cellular and Antibody-Mediated Immune Responses in Mice

    No full text
    Adjuvants are essential components of subunit vaccines added to enhance immune responses to antigens through immunomodulation. Very few adjuvants have been approved for human use by regulatory agencies due to safety concerns. Current subunit vaccine adjuvants approved for human use are very effective in promoting humoral immune responses but are less effective at promoting T-cell immunity. In this study, we evaluated a novel pure enantio-specific cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (R-DOTAP) as an immunomodulator for subunit vaccines capable of inducing both humoral- and cellular-mediated immunity. Using recombinant protein antigens derived from SARS-CoV2 spike or novel computationally optimized broadly reactive influenza antigen (COBRA) proteins, we demonstrated that R-DOTAP nanoparticles promoted strong cellular- and antibody-mediated immune responses in both monovalent and bivalent vaccines. R-DOTAP-based vaccines induced antigen-specific and polyfunctional CD8+ and CD4+ effector T cells and memory T cells, respectively. Antibody responses induced by R-DOTAP showed a balanced Th1/Th2 type immunity, neutralizing activity and protection of mice from challenge with live SARS-CoV2 or influenza viruses. R-DOTAP also facilitated significant dose sparing of the vaccine antigens. These studies demonstrate that R-DOTAP is an excellent immune stimulator for the production of next-generation subunit vaccines containing multiple recombinant proteins
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