Development of heat transfer and pressure drop correlations in twisted tube heat exchangers

Heat transfer in concentric twisted tubes exchangers has several applications in the chemical and food industry mainly due to its compact structure and high transport coefficients, however, its use has been limited as a consequence of drop pressure. This study reports Nusselt number and friction factor correlations as a function of the dimensionless Dean number as well as Prandtl number, and a torsional step parameter. Simulations were carried out using ANSYS CFX® V16.0 software at workstations belonging to Grupo de Investigación en Materiales Avanzados y Energía of Instituto Tecnológico Metropolitano. Six geometries were developed with SolidEdge® ST9 academic license. Geometry modification, cleanup, and repair were made although DesignModeler® 2019 academic license. Finally Meshing® for discretization. The mesh size independence, and incidence of the turbulence model, and twisting step validated the computational tools use. Correlation numerically showed an increase of 60% average respect to smooth bending tube. © Published under licence by IOP Publishing Lt

Ant-mediated seed dispersal in a warmed world

Climate change affects communities both directly and indirectly via changes in interspecific interactions. One such interaction that may be altered under climate change is the ant-plant seed dispersal mutualism common in deciduous forests of eastern North America. As climatic warming alters the abundance and activity levels of ants, the potential exists for shifts in rates of ant-mediated seed dispersal. We used an experimental temperature manipulation at two sites in the eastern US (Harvard Forest in Massachusetts and Duke Forest in North Carolina) to examine the potential impacts of climatic warming on overall rates of seed dispersal (using Asarum canadense seeds) as well as species-specific rates of seed dispersal at the Duke Forest site. We also examined the relationship between ant critical thermal maxima (CTmax) and the mean seed removal temperature for each ant species. We found that seed removal rates did not change as a result of experimental warming at either study site, nor were there any changes in species-specific rates of seed dispersal. There was, however, a positive relationship between CTmax and mean seed removal temperature, whereby species with higher CTmax removed more seeds at hotter temperatures. The temperature at which seeds were removed was influenced by experimental warming as well as diurnal and day-to-day fluctuations in temperature. Taken together, our results suggest that while temperature may play a role in regulating seed removal by ants, ant plant seed-dispersal mutualisms may be more robust to climate change than currently assumed

Assessment of virulence factors characteristic of human Escherichia coli pathotypes and antimicrobial resistance in O157:H7 and non-O157:H7 isolates from Livestock in Spain

The distribution of virulence factors (VFs) typical of diarrheagenic Escherichia coli and the antimicrobial resistance (AMR) profiles were assessed in 780 isolates from healthy pigs, broilers, and cattle from Spain. VF distribution was broader than expected, although at low prevalence for most genes, with AMR being linked mainly to host species

IMPLICACIONES PARA EL ESTUDIO DE LA NEUROBIOLOGÍA DE LA EXPERIENCIA CONSCIENTE. EL ACTO IMPULSIVO

Conciencia e impulsividad son dos constructos multidimensionales relacionados con el control del pensamiento y comportamiento humano. Impulsividad es un rasgo de personalidad complejo caracterizado por una elevada tendencia a actuar sin pensar, incapacidad para planear actividades futuras y disminución de la capacidad de concentración. Conciencia por su parte, es un constructo que cobija una serie de procesos fisiológicos relacionados con la generación de experiencia conciente y la adquisición de conocimientos. Con respecto al control sobre la acción humana, conciencia e impulsividad parece estar relacionados con comportamientos opuestos. Históricamente, los esfuerzos realizados por diversas disciplinas con el fin de estudiar estos constructos han llevado al desarrollo de definiciones divergentes y a una serie de medidas, causando una mayor confusión. Los propósitos de este artículo son: 1) describir ejemplos de posibles soluciones al estado de confusión en el campo de la investigación sobre impulsividad y discutir como el estudio de la conciencia puede beneficiarse de la investigación de la impulsividad; 2) discutir algunas de las maneras utilizadas para medir impulsividad en el laboratorio y cómo hacer de estos constructos variables experimentales; 3) resumir algunas de las lecciones derivadas de la comparación de los actos impulsivos con los premeditados desde una perspectiva integral y multidimensional; 4) discutir las implicaciones derivadas del uso de un enfoque multidimensional para el estudio de la conciencia

Estudio de la microviscosidad de la Hemoglobina A (HbA) y la Hemoglobina S (HbS) en condiciones de desoxigenación espontánea

La microviscosidad de la hemoglobina A y la hemoglobina S es analizada en muestras con concentración intracelular, durante el proceso de desoxigenación espontánea y a 36 ºC, empleando glutatión y carbonmonoxihemoglobina, marcados con 4-maleimido-tempo. El glutatión marcado muestra un comportamiento constante de la microviscosidad de la hemoglobina S durante el estudio. La carbonmonoxihemoglobina marcada muestra un incremento de la microviscosidad durante el proceso de polimerización de la hemoglobina S, lo cual pudiera explicar el comportamiento de los tiempos de relajación magnética protónica determinados en otros artículos para las mismas muestras. Tanto el glutatión como la carbonmonoxihemoglobina marcados, reportan un comportamiento constante de la microviscosidad en la hemoglobina A.The Microviscosity of hemoglobin A and hemoglobin S are analyzed in samples of intracellular concentration, during the free deoxygenation process and at 36 ºC, using Glutathione and Carbonmonoxihemoglobin labeled with 4-maleimido-tempo. Labeled Glutathione shows a constant behaviour of the hemoglobin S microviscosity during the study. Labeled Carbonmonoxihemoglobin shows an increase of the microviscosity during the hemoglobin S polymerization process, which could explain the proton relaxation times behaviour determined in other articles for the same samples. Labeled Glutathione and Carbonmoxihemoglobing report constant behaviour of microviscosity in hemoglobin A.Fil: Lores, M.. Universidad de Oriente; CubaFil: Cabal, C.. Universidad de Oriente; CubaFil: Nascimento, Otaciro R.. Universidade de Sao Paulo; BrasilFil: Gennaro, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Accumulation of northern krill (Meganyctiphanes norvegica) in a convergence zone at the Cap Breton Canyon (southern Bay of Biscay)

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