Comportamiento cíclico de una acero St-52-3N: Influencia de los módulos de elasticidad en las estimaciones de vida a fatiga

Dada la dependencia de los módulos de elasticidad en los métodos de estimación de vida a fatiga, se analiza el comportamiento cíclico y la variación de estos con el grado de deformación. En este estudio se llevan a cabo una serie de experimentos de fatiga uniaxial en control de deformación, con R=-1, a bajo número de ciclos y a temperatura ambiente, para caracterizar el comportamiento cíclico del acero al carbono St-52-3N. Se realizaron ensayos de fatiga uniaxial tanto de tracción como de torsión. Se compara los valores de los módulos de elasticidad monotónico y cíclico, además de los valores cíclicos correspondientes a los segmentos de descarga y carga (E1 ,E2) (acordes con ISO/DIS 121106). Se pone de manifiesto la variabilidad cometida al calcular el incremento de deformación plástica según el Método Estándar de ensayo que utilicemos (BS/ISO, ASTM, AECMA) y que determinará en cada caso la estimación del módulo de elasticidad cíclicoUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Estudio experimental y numérico del comportamiento de un modelo de difusor de aire por desplazamiento acoplado a un suelo frío

En la última década se han realizado muchos trabajos sobre sistemas de refrigeración para grandes superficies usando ventilación por desplazamiento con suelos radiantes (por ejemplo en aeropuertos y estaciones). De especial interés tiene el conocimiento de los campos de velocidad y de temperatura. De forma simplificada, en este estudio se presentan los resultados de un difusor a escala que utiliza ventilación por desplazamiento con suelo radiante frío. Tres son los parámetros que se modifican: el caudal (Q), la diferencia entre la temperatura ambiente y el aire de impulsión (dT1) y la diferencia entre la temperatura del suelo y el aire de impulsión (dT2). Las visualizaciones y mediciones del campo de velocidad del flujo se han realizado para un régimen laminar en estado estacionario. Además, las simulaciones numéricas del campo de temperatura representado en la figura muestran buena concordancia con los datos experimentales. Las zonas de mayor interés en este estudio son: la salida del difusor, la zona cercana al suelo y la zona lejos del difusor sobre el suelo, donde las condiciones de contorno se discuten con detalle. La distancia radial (r) para la que cada difusor afecta a su alrededor en los términos de gradiente de temperatura y de velocidad es un parámetro importante para el diseño de la distribución espacial de estos difusores. Los principales resultados de este trabajo se basan en la relación r = f (Q, dT1, dT2).AIRZON

DmeRF system is required for nickel and cobalt resistance in Rhizobium leguminosarum bv. viciae.

A member of the Cation Diffusion Facilitator (CDF) family with high sequence similarity to DmeF (Divalent metal efflux) from Cupridavirus metallidurans was identified in Rhizobium leguminosarum bv. viciae UPM1137. The R. leguminosarum dmeF mutant strain was highly sensitive to Co2+ and moderately sensitive to Ni2+, but its tolerance to other metals such as Zn2+, Cu2+ or Mn2+ was unaffected. An open reading frame located upstream of R. leguminosarum dmeF, designated dmeR, encodes a protein homologous to the nickel and cobalt regulator RcnR from E.coli. Expression of the dmeRF operon was induced by nickel and cobalt ions in free-living cells, likely by alleviating DmeR-mediated transcriptional repression of the operon

Identificación y caracterización funcional de sistemas génicos implicados en la homeostasis de níquel en Rhizobium leguminosarum bv. viciae

La homeostasis de metales como níquel, cobalto, cobre o zinc es un proceso delicado en procariotas. Estos metales de transición son, por un lado imprescindibles para el mantenimiento del metabolismo celular, pero por otro muy tóxicos a elevadas concentraciones. Por este motivo, los microorganismos han desarrollado mecanismos para regular su concentración intracelular, tales como bombas de flujo de metales, secuestradores intra y extracelulares o enzimas detoxificadoras

(Position Paper) Characterizing the Behavior of Small Producers in Smart Grids:A Data Sanity Analysis

Renewable energy production throughout low-voltage grids has gradually increased in electrical distribution systems, therefore introducing small energy producers - prosumers. This paradigm challenges the traditional unidirectional energy distribution flow to include disperse power production from renewables. To understand how energy usage can be optimized in the dynamic electrical grid, it is important to understand the behavior of prosumers and their impact on the grid’s operational procedures. The main focus of this study is to investigate how grid operators can obtain an automatic data-driven system for the low-voltage electrical grid management, by analyzing the available grid topology and time-series consumption data from a real-life test area. The aim is to argue for how different consumer profiles, clustering and prediction methods contribute to the grid-related operations. Ultimately, this work is intended for future research directions that can contribute to improving the trade-off between systematic and scalable data models and software computational challenges.This work is financially supported by the Danish project RemoteGRID, which is a ForskEL program under Energinet.dk with grant agreement no. 2016-1-12399.Peer ReviewedPostprint (published version

Functional characterization of Rhizobium leguminosarum bv. viciae DmeRF, a cation diffusion facilitator system involved in nickel and cobalt resistance

In prokaryotes, nickel is an essential element participating in the structure of enzymes involved in multiple cellular processes. Nickel transport is a challenge for microorganisms since, although essential, high levels of this metal inside the cell are toxic. For this reason, bacteria have developed high-affinity nickel transporters as well as nickel-specific detoxification systems. Ultramafic soils, and soils contaminated with heavy metals are excellent sources of nickel resistant bacteria. Molecular analysis of strains isolated in the habitats has revealed novel genetic systems involved in adaptation to such hostile conditions

Identificación y análisis funcional de genes implicados en la homeostasis de níquel en la bacteria endosimbiótica de leguminosas Rhizobium leguminosarum

La asociación Rhizobium-leguminosa constituye una interacción planta-microorganismo particularmente beneficiosa a nivel medioambiental debido a su capacidad promotora del crecimiento vegetal en condiciones de deficiencia de nitrógeno. Se ha demostrado que una excesiva concentración de metales pesados en el suelo afecta negativamente la competitividad bacteriana y al desarrollo de interacciones diazotróficas eficientes (Chaudri et al., 2000; Pereira et al., 2006). Por otro lado, el suministro de metales como Fe, Mo, Ni o Cu es fundamental para la biosíntesis de enzimas bacterianas relacionadas con el proceso de fijación de nitrógeno que ocurre en el interior de los nódulos de las leguminosas (Moreau et al., 1995). Con objeto de identificar sistemas génicos implicados en la homeostasis de níquel en bacterias endosimbióticas, se ha llevado a cabo una mutagénesis mediante inserción aleatoria de un minitransposón derivado de Tn5 en Rhizobium leguminosarum bv. viciae UPM1137, una cepa capaz de resistir elevadas concentraciones de níquel y cobalto. Como resultado de esta mutagénesis se han obtenido 14 mutantes incapaces de crecer en medios suplementados con NiCl2. La localización de la inserción en estos mutantes muestra que una elevada proporción de los genes afectados codifican proteínas de membrana o proteínas secretadas. En paralelo, se ha obtenido la secuencia del genoma de la cepa UPM1137, lo que permite realizar estudios in silico comparando los genomas disponibles de varias cepas de R. leguminosarum bv. viciae, que presentan una menor sensibilidad a metales. El análisis bioinformático de los genomas secuenciados y la caracterización fenotípica de los mutantes obtenidos permitirá identificar potenciales sistemas de resistencia y su contribución a la homeostasis de metales

Identification and functional characterization of Rhizobium leguminosarum bv. viciae genetic systems involved in nickel homeostasis.

A collection of Rhizobium leguminosarum bv. viciae strains isolated from ultramafic and contaminated soils in Italy and Germany, respectively, was analyzed for resistance to nickel and cobalt ions. These assays led to the identification of strain UPM1137, which is able to grow at high concentrations of nickel and cobalt. In order to identify genetic systems involved in the homeostasis to these metals, a random mutagenesis was carried out in UPM1137 by inserting a Tn5-derivative minitransposon. As a result 4313 transconjugants were obtained, being 39 of them (0.90%) unable to grow at 1.5 mM NiCl2. The identification of the transposon insertion site in these mutants showed that the disrupted genes encode proteins belonging to different functional categories, where the secreted and membrane proteins were the most numerous. The analysis of heavy metal resistance and phenotypes in symbiotic and free –living cells will define the contribution of these genes to metal homeostasis

Production and evaluation of antimicrobial microcapsules with essential oils using complex coacervation

Nowadays, the needs and requirements to avoid infections during surgical operations, require to be more imaginative than ever. The one-use textiles substrates that are used in hospitals can be, also, a way to transport the antibacterial effect around the own building. This is the main objective of this work; to use clothes and textiles surfaces as antibacterial systems using natural components. Microencapsulation has shown in several occasions the effectivity to protect and vehiculize active principles that can be used for medical treatments. In this case, essential oils have been used as antimicrobial agent, that when combined with shell polymers based on Chitosan of different molecular weight distribution and Arabic gum, allows them to act against Gram (+) and Gram (-) bacteria. The study of the efficiency of all the samples made gave a high value due to its character similar to hydrogels, while the determination of solids was higher when it was a question of samples made with a low molecular weight. The essential oil used has a very volatile character formed by more than 40 components and with the help of FT-IR and TGA it has been possible to corroborate that all its components were encapsulated. The impregnation of the different samples to the tissue was successful and allowed the antibacterial study to be carried out, which was carried out in duplicate on each sample and demonstrated that they have bacterial activityPostprint (published version

Identification and analysis of a nickel-inducible cation diffusion facilitator-NiCoT combined system in Rhizobium leguminosarum bv. viciae

Nickel, like other transition metals, can be toxic to cells even at moderate concentration (low microM range) by displacing essential metals from their native binding sites or by generating reactive oxygen species that cause oxidative DNA damage. For this reason, cells have evolved mechanisms to deal with excess nickel. Efflux systems include members of the Resistance-Nodulation-cell Division (RND) protein family, P-type ATPases, cation diffusion facilitators (CDF) and other resistance factors. Nickel-specific exporters have been characterized in Cupravidus metallidurans, Helicobacter pylori, Achromobacter xylosoxidans, Serratia marcenses and Escherichia coli