Study of the stress intensity factors in the bulk of the material with synchrotron diffraction

Artículo de Proceedings de Congreso Internacional Fatigue2017In this work we present the results of a hybrid experimental and analytical approach for estimating the stress intensity factor. It uses the elastic strains within the bulk obtained by synchrotron X-ray diffraction data. The stress intensity factor is calculated using a multi-point overdeterministic method where the number of experimental data points is higher than the number of unknowns describing the elastic field surrounding the crack-tip. The tool is tested on X-ray strain measurements collected on a bainitic steel. In contrast to surface techniques the approach provides insights into the crack tip mechanics deep within the sample.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. The authors are grateful to the ESRF for ID15 beamtime awarded under MA-1483. Financial support of Universidad de Malaga through Plan Propio, Junta de Andalucía through Proyectos de Excelencia grant reference TEP-3244, Campus de Excelencia Internacional del Mar (CEIMAR) and Ministerio de Economia y Competitividad through grant reference MAT2016-76951-C2-2-P is also acknowledged. PJW acknowledges an ERC advanced grant

FAM-1 Borehole: first results from the scientific drilling of the Alhama de Murcia Fault, Betic Cordillera, Spain

We present the preliminary results of the borehole FAM-1 a 175 m depth scientific drilling of the Alhama de Murcia fault. The borehole was drilled close to La Torrecilla rambla three km SW of Lorca where the fault zone shearing is more concentrated and it is dominated by well-developed clay rich fault gouge. To select the drilling point and to perform a prognosis of it, three trenches were excavated crossing the fault zone that allowed us to determine the detailed 3D structure of the fault zone. We have collected more than 100 m of unaltered high quality fault rock to be studied using mineralogical and microtectonic analysis, and geomechanical testing that will improve the knowledge of the influence of tectonic microfabric and mineralogy in the seismogenic behavior of the AMF. The borehole FAM-1 and the seismic monitoring borehole FamSis-1 constitute the first stage of a future geological-geophysical observatory for monitoring the activity of the AMF.This research is part of the INTERGEO project: CGL2013-47412-C2-1-P.Peer Reviewe

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

Solvent-free process for the development of photocatalytic membranes

PTDC/EAM-AMB/30989/2017.This work described a new sustainable method for the fabrication of ceramic membranes with high photocatalytic activity, through a simple sol-gel route. The photocatalytic surfaces, prepared at low temperature and under solvent-free conditions, exhibited a narrow pore size distribution and homogeneity without cracks. These surfaces have shown a highly efficient and reproducible behavior for the degradation of methylene blue. Given their characterization results, the microfiltration photocatalytic membranes produced in this study using solvent-free conditions are expected to effectively retain microorganisms, such as bacteria and fungi that could then be inactivated by photocatalysis.publishe

Novel submerged photocatalytic membrane reactor for treatment of olive mill wastewaters

POCI-01-0145-FEDER-007265A new hybrid photocatalytic membrane reactor that can easily be scaled-up was designed, assembled and used to test photocatalytic membranes developed using the sol–gel technique. Extremely high removals of total suspended solids, chemical oxygen demand, total organic carbon, phenolic and volatile compounds were obtained when the hybrid photocatalytic membrane reactor was used to treat olive mill wastewaters. The submerged photocatalytic membrane reactor proposed and the modified membranes represent a step forward towards the development of new advanced treatment technology able to cope with several water and wastewater contaminants.publishersversionpublishe

Neutrophil infiltration regulates clock-gene expression to organize daily hepatic metabolism

Liver metabolism follows diurnal fluctuations through the modulation of molecular clock genes. Disruption of this molecular clock can result in metabolic disease but its potential regulation by immune cells remains unexplored. Here, we demonstrated that in steady state, neutrophils infiltrated the mouse liver following a circadian pattern and regulated hepatocyte clock-genes by neutrophil elastase (NE) secretion. NE signals through c-Jun NH2-terminal kinase (JNK) inhibiting fibroblast growth factor 21 (FGF21) and activating Bmal1 expression in the hepatocyte. Interestingly, mice with neutropenia, defective neutrophil infiltration or lacking elastase were protected against steatosis correlating with lower JNK activation, reduced Bmal1 and increased FGF21 expression, together with decreased lipogenesis in the liver. Lastly, using a cohort of human samples we found a direct correlation between JNK activation, NE levels and Bmal1 expression in the liver. This study demonstrates that neutrophils contribute to the maintenance of daily hepatic homeostasis through the regulation of the NE/JNK/Bmal1 axis

Deciphering the function and evolution of the TOR signaling pathway in microalgae

Microalgae constitute a highly diverse group of photosynthetic microorganisms that are widely distributed on Earth. The rich diversity of microalgae arose from endosymbiotic events that took place early in the evolution of eukaryotes and gave rise to multiple lineages including green algae, the ancestors of land plants. In addition to their fundamental role as the primary source of marine and freshwater food chains, microalgae are essential producers of oxygen in the planet and a major biotechnological target for sustainable biofuel production and CO2 mitigation. Microalgae integrate light and nutrient signals to regulate cell growth. Recent studies identified the target of rapamycin (TOR) kinase as central regulator of cell growth and nutrient sensor in microalgae. TOR promotes protein synthesis and regulates processes that are induced under nutrient stress such as autophagy and the accumulation of triacylglycerol and starch. A detailed analysis of representative genomes from the entire microalgal lineage revealed the high conservation of central components of the TOR pathway likely present in the last eukaryotic common ancestor and the loss of specific TOR signaling elements at an early stage in the evolution of microalgae. Here we examine the evolutionary conservation of TOR signaling components in diverse microalgae and discuss recent progress on the study of this signaling pathway in these organisms.Ministerio de Ciencia y Tecnología PGC2018-099048-B-I00, PID2019-110080GB-I0

Evaluación de la zona plástica en fatiga para un acero bainitico mediante difracción de rayos x

En este artículo se presenta una nueva metodología para medir la zona plástica de una grieta en fatiga. Se han adquirido datos de difracción de rayos X sincrotrón para una probeta Compact Tension de acero bainítico, en el plano medio a través del espesor. Estos datos han sido traducidos a campos 2D de deformación en torno al vértice. Se ha generado un campo de deformación angular artificial para, en consonancia con los anteriores, obtener el campo de deformación equivalente de Von Mises. La aplicación de la ley de comportamiento elástico ha permitido hallar campos de tensión equivalente entorno al vértice de grieta. Así, se permite estimar la zona plástica y sus dimensiones. Finalmente se estudia la precisión de la metodología a través de una comparación con los modelos de zona plástica de Irwin y de Dugdale.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech Los autores agradecen la financiación aportada para la realización de este trabajo al Ministerio de Economía y Competitividad (referencia MAT2016-76951-C2-2-P) y al Fondo Social Europeo a través de la Iniciativa de Empleo Juvenil (referencia UMAJI84)

Determinación experimental de la carga de apertura de grieta en fatiga bajo cargas aleatorias

El concepto de carga de apertura o cierre de grieta es ampliamente utilizado en fatiga para justificar el comportamiento del crecimiento de grietas con distintas relaciones de carga y el efecto de interacción de las cargas. Hasta la fecha son numerosas las técnicas experimentales propuestas para medir la apertura de grieta y entre ellas los métodos de flexibilidad son ampliamente utilizados por su simplicidad. En este trabajo se propone una modificación del método propuesto por la ASTM y se presentan los resultados obtenidos en ensayos de crecimiento de grietas por fatiga bajo cargas aleatorias. Así mismo, los valores experimentales de cargas de apertura son comparados con los calculados analíticamente por un modelo de simulación tipo “strip-yield” implementado en el software NASGRO. En general, se ha encontrado una concordancia razonablemente buena entre los valores experimentales y los obtenidos por simulación.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Los autores agradecen la financiación aportada para la realización de este trabajo al Ministerio de Economía y Competitividad (referencia MAT2016-76951-C2-2-P)

Influencia del tamaño mínimo de elemento en el análisis tridimensional por elementos finitos del cierre de grieta inducido por plasticidad

Because of the increase of the computational power, during last years the use of three-dimensional finite element models to analyse the plasticity induced crack closure phenomenon has spread. However, the methodology employed is directly inherit from bi-dimensional analysis. As is well known, several numerical parameters can affect to the obtained results, being one of them, the mesh size close to the crack front. In the present work, a CT aluminium alloy specimen has been three-dimensionally modelled in order to analyse the influence of the mesh size close to the crack front. The results have been analysed in terms of the crack opening and closure values as well as taking into account the strain and stress fields around the crack front.Debido al incremento de la capacidad computacional disponible hoy en día, en los últimos años se ha extendido el uso de modelos tridimensionales para el análisis del cierre de grieta en fatiga empleando el método de los elementos finitos. Sin embargo, la metodología que se emplea es directamente heredada de los modelos bidimensionales. Es bien conocido que diferentes parámetros numéricos pueden afectar a los resultados obtenidos, siendo uno de ellos el tamaño de la malla en el entorno del frente de la grieta. En el presente trabajo, se ha modelado tridimensionalmente una probeta CT de una aleación de aluminio, con objeto de evaluar la influencia del tamaño de la malla en el entorno del frente de la grieta, analizando los resultados en función de los valores de apertura y cierre de la grieta, así como considerando los campos de tensiones y deformaciones entrono al frente de la grieta.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech