610 research outputs found

    Numerical studies of Newtonian and viscoelastic fluids

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    The direct numerical simulation (DNS) approach is used to understand the flow behavior of Newtonian and viscoelastic fluids in porous materials, four-to-one contraction and the flow of a Newtonian fluid past an airfoil. In simulations the viscoelastic fluid is modeled by the finitely extensible nonlinear elastic (FENE) dumbbell and Oldroyd-B models. The finite element method (FEM) is used to discretize the flow domain. The DNS results show that the permeability of a periodic porous medium depends on the wavelength used for arranging particles in the direction of flow. Specifically, it is shown that for a given particle size and porosity the permeability varies when the distance between particles in the flow direction is changed. The permeability is locally minimum for kD [approximately equal to] 7.7 and locally maximum for kD [approximately equal to] 5.0; where k is the wave number and D the diameter. A similar behavior holds for a viscoelastic fluid, except that the variation of permeability with kD is larger than for the Newtonian case. For flow in the four-to-one contraction, it is found that the stress near the 3Ď€/2 comer is singular and that the singularity is stronger than for a Newtonian liquid. In the region away from the walls, the stress varies as r -0.47 and near the walls it varies as r -0.61. Since the singularity is integrable, the flow away from the comer is not effected [sic] when the flow around the comer is resolved by using a radial mesh with sufficient resolution in the tangential direction at the comer. The DNS approach is also used to demonstrate that the boundary layer separation on the upper surface of the airfoil can be suppressed by placing injection and suction regions on the upper surface. The simulations are performed for Re ≤ [less than or equal too] 500 and angle of attack up to 40°. Analysis of numerical results shows that the pressure contribution to drag decreases when the boundary layer separation is avoided. The viscous contribution to drag, however, increases and thus there is only a negligible decrease in the total drag for Re ≤ [less than or equal too] 500. Another beneficial effect of suction and injection is that the pressure contribution to the lift increases and the stall is avoided

    Report on High Performance Building's Energy Modeling, Physical Building Information Modeling for Solar Building Design and Simulation

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    This report was created for the National Science Foundation-Physical Building Information Modeling (NSF-PBIM) project. This report describes the analysis of a solar office building using the following software: the legacy tools (DOE 2.1e, the F-Chart and the PV-F Chart) for whole-building energy analysis, solar thermal analysis and solar electric analysis; the Revit software that was used to render the images of the solar office building and get feedback for the DOE-2.1e; and the Inverse Model Toolkit (IMT) program to transfer data between the legacy tools during the first two years of the National Science Foundation Physical Building Information Modeling (NSF PBIM) project at Texas A&M University. The results show that the high performance solar office building reduced annual energy consumption by 100 (i.e., Net Zero) percent in both Houston and Denver as compared to a regular office building. In other words, the Net-Zero Energy Office Building which was designed with legacy tools, produces as much as or more energy than it consumes. The solar office building used different renewable energy systems, such as a solar Domestic Hot Water (DHW) system, clerestory windows, daylighting sensors and photovoltaic panels to achieve the Net-Zero Energy Building level

    Lista patrĂłn de los tiburones, rayas y quimeras (Chondrichthyes, Elasmobranchii, Holocephali) de MĂ©xico

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    Llista patró dels taurons, rajades i quimeres (Chondrichthyes, Elasmobranchii, Holocephali) de Mèxic Es presenta una relació de les espècies de taurons, rajades  i quimeres (condrictis) que han estat registrades a les aigües territorials de Mèxic, basada en revisions de bases de dades, literatura, examen físic dels espècimens de col·leccions científiques i registres d’exemplars recol·lectats en treballs de camp durant els darrers quatre anys i que no han estat publicats. La relació conté informació de 214 espècies de condrictis que, com a mínim, han estat registrades a les aigües marines i salobroses de Mèxic, pertanyents a 84 gèneres, 40 famílies i 14 ordres. S’hi inclouen vuit espècies de quimeres, 95 de batoïdeus i 111 de taurons. La condrictiofauna mexicana és una de les més riques del món, amb el 17,3% o més de les espècies conegudes. A més a més, s’ hi inclouen 16 espècies que és probable que siguin presents a Mèxic atesos els seus patrons de distribució.Checklist of sharks, rays and chimaeras (Chondrichthyes, Elasmobranchii, Holocephali) from Mexico We present an annotated checklist of the species of sharks, rays and chimaeras (chondrichthyan fishes) occurring in Mexican waters, based on a thorough review of the literature and electronic database searches, examination of museum collection specimens, and unpublished records obtained during fieldwork conducted in the last four years. The checklist contains information of at least 214 species of chondrichthyan fishes that occur in Mexican marine and brackish waters, assigned to 84 genera, 40 families and 14 orders. It includes eight species of chimaeras, 95 batoids and 111 sharks. Condrichthyan fauna in Mexico is one of the richest in the world, with almost 17.3% of the known species. An additional  16 species are included  as their occurrence in Mexican marine waters is probable according to distributional patterns.Se presenta un listado anotado de las especies de tiburones, rayas y quimeras (Condrictios) que han sido registrados en las aguas territoriales de México, basado en revisiones de bases de datos, literatura, examinación física de los especímenes de colecciones científicas y de registros de ejemplares recolectados en campo durante los últimos cuatro años y que no han sido publicados. El listado contiene información de al menos 214 especies de condrictios que se han registrado en las aguas marinas y salobres de México, pertenecientes a 84 géneros, 40 familias y 14 órdenes. Se incluyen ocho especies de quimeras, 95 de batoideos y 111 de tiburones. La condrictiofauna mexicana es una de las más ricas a nivel mundial, con al menos 17.3% de las especies conocidas. Adicionalmente, 16 especies, se incluyen como especies probables que ocurran en México debido a sus patrones de distribución.Palabras clave: Condrictios, Elasmobranquios, Batoideos, Quimeras, México

    Low Impact, Affordable, Low Income Houses for Mexico

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    This paper discusses an effort to develop low impact, affordable, low income houses for Mexico. Low impact houses are defined as houses with energy and water needs that are substantially reduced below levels corresponding to code compliance. This paper includes an analysis of the population and energy consumption of the different climate regions in Mexico (Hot-Dry Deserts, Great Plains, Mediterranean, Semi-Arid, Temperate, Hot-Dry Jungles and Hot-Humid Jungles) versus the USA and concludes with advice on an approach for low impact housing.Department of Architecture, Texas A&M Universit

    Towards a surrogate system to express human lipid binding TCRs

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    BackgroundPreviously we reported that natural nut lipids were necessary for sensitization and that natural killer T cells (NKTs) must play a critical role in the development of food allergic responses. A major bottleneck in further understanding the interaction of nut lipids with the cells of the human immune system is the lack of well-characterized lipid responsive human cell lines.ObjectiveIn the present study, we engineered human T cell receptor (TCR) sequences TRAV10 and TRBV25 responsive to α-GalCer into a stable murine iNKT hybridoma and surrogate human T cell lines.ResultsThe murine hybridoma system has shown to be problematic. To overcome this limitation, the expression of human TCR α/β sequences has been achieved driven by a bidirectional promoter on a plasmids or a lentivirus system, employing stable DC cell lines as lipid presenting cells, and a stable T cell line as a surrogate system. Further, a commercial human Jurkat T cell line containing an inducible secreted luciferase reporter construct was shown to be functional and can be used for a transient expression of human TCRs in a lipid screening program. The transfection efficiencies were improved using the lentivirus polycistronic constructs containing the P2A sequence in a TCR αβ/γδ null cell line (Jurkat 76).ConclusionsThe results suggest that the mis-pairing of the endogenous α/β TCR during ER folding in the presence of the new human TCR sequences could be impairing the functionality of the TCR lipid receptors. The surrogate systems presented here are important first steps in the establishment of human cell-specific lipid responsive libraries for the study of natural lipid substances

    Projecting the long-term benefits of single pill combination therapy for patients with hypertension in five countries.

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    Objective: To project the 10-year clinical outcomes associated with single pill combination (SPC) therapies compared with multi-pill regimens for the management of hypertension in five countries (Italy, Russia, China, South Korea and Mexico). Methods: A microsimulation model was designed to project health outcomes between 2020 and 2030 for populations with hypertension managed according to four different treatment pathways: current treatment practices (CTP), single drug with dosage titration then sequential addition of other agents (start low and go slow, SLGS), free choice combination with multiple pills (FCC) and combination therapy in the form of a single pill (SPC). Model inputs were derived from the Global Burden of Disease 2017 dataset. Simulated outcomes of mortality, chronic kidney disease (CKD), stroke, ischemic heart disease (IHD), and disability-adjusted life years (DALYs) were estimated for 1,000,000 patients on each treatment pathway. Results: SPC therapy was projected to improve clinical outcomes over SLGS, FCC and CTP in all countries. SPC reduced mortality by 5.4% in Italy, 4.9% in Russia, 4.5% in China, 2.3% in South Korea and 3.6% in Mexico versus CTP and showed greater reductions in mortality than SLGS and FCC. The projected incidence of clinical events was reduced by 11.5% in Italy, 9.2% in Russia, 8.4% in China, 4.9% in South Korea and 6.7% in Mexico for SPC versus CTP. Conclusions: Ten-year projections indicated that combination therapies (FCC and SPC) are likely to reduce the burden of hypertension compared with conventional management approaches, with SPC showing the greatest overall benefits due to improved adherence

    Anti-Food allergic activity of sulfated polysaccharide from Gracilaria lemaneiformisis dependent in immunosuppression and inhibition of p38 MAPK

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    Polysaccharides from Gracilaria lemaneiformis in particular possess various bioactive functions, but their antiallergic activity remains incompletely defined. Sulfated polysaccharide from Gracilaria lemaneiformis (GLSP) was obtained by water extraction and ethanol precipitation followed by column chromatography. BALB/c mice, RBL-2H3, and KU812 cells were used for verifying the anti food allergic activity of GLSP. According to the results of mice experiment, GLSP was able to alleviate allergy symptoms, to reduce TM-specific IgE and IgG1, to suppress Th2 cell polarization, and to promote the function of regulatory T (Treg) cells. In addition, GLSP had the ability to inhibit the function of RBL-2H3 cells. Furthermore, GLSP inhibited the activation of KU812 via suppression of p38 mitogen-activated protein kinase (MAPK). In conclusion, immunosuppression as well as the reduction in the level of p38 MAPK may contribute to GLSP’s putative activity against food allergy. GLSP may be used as a functional food component for allergic patients

    Ultrafast THz probe of photo-induced polarons in lead-halide perovskites

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    We study the nature of photo-excited charge carriers in CsPbBr3 nanocrystal thin films by ultrafast optical pump - THz probe spectroscopy. We observe a deviation from a pure Drude dispersion of the THz dielectric response that is ascribed to the polaronic nature of carriers; a transient blueshift of observed phonon frequencies is indicative of the coupling between photogenerated charges and stretching-bending modes of the deformed inorganic sublattice, as confirmed by DFT calculations
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