Experimental and analytical study of cracks under biaxial fatigue

Most mechanical components experience multi-axial cyclic loading conditions during service. Experimental analysis of fatigue cracks under such conditions is not easy and most works tend to focus more on the simpler but less realistic case of uni-axial loading. Consequently, there are many uncertainties related to the load sequence effect that are now well known and are not normally incorporated into the growth models. The current work presents a new methodology for evaluating overload effect in biaxial fatigue cracks. The methodology includes evaluation of mixed-mode (KI and KII) stress intensity factor and the Crack Opening Displacement for samples with and without overload cycle under biaxial loading. The methodology is tested under a range of crack lengths. All crack-tip information is obtained with a hybrid methodology that combines experimental full-field digital image correlation data and Williams' elastic model describing the crack-tip field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sobrecargas en crecimiento de grietas por fatiga biaxial

El presente trabajo se centra en el estudio de grietas de fatiga bajo cargas biaxiales. Se presenta una nueva metodología para evaluar el efecto de las sobrecargas basada en la evaluación experimental del factor de intensidad de tensiones efectivo y de la apertura de la grieta (Crack Opening Displacement, COD). El estudio se ha realizado en probetas cilíndricas de acero de bajo contenido en carbono sometidas a cargas de tracción y torsión. Los datos experimentales se han obtenido mediante la técnica de correlación de imágenes digitales. Se ha comparado la evolución de la grieta con y sin sobrecarga. Además, se ha utilizado un procedimiento de detección de carga de apertura. Dicho procedimiento se había desarrollado previamente en fatiga uniaxial para el caso biaxial. Dicho procedimiento permite poner de manifiesto el cambio originado por un ciclo de sobrecarga.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

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)

Métodos de plano crítico para el análisis de fatiga multiaxial en el acero inoxidable 316

El presente trabajo estudia la capacidad de predicción de los modelos de plano crítico para casos de fatiga multiaxial. El material que se estudia es un acero inoxidable 316. Los caminos de carga aplicados son uniaxiales y biaxiales en la superficie de la probeta. El siguiente estudio realiza una comparativa de las predicciones de vida a fatiga y ángulo de grieta de los modelo Wang-Brown, Fatemi-Socie, Liu I y Liu II. Se observó que la mejor predicción de vida fue devuelta por el modelo de Liu II y para el ángulo de grieta por Liu I.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)

Up-regulation of HDACs, a harbinger of uraemic endothelial dysfunction, is prevented by defibrotide

Altres ajuts: This work was supported by Jazz Pharmaceuticals Plc (IST-16-10355 to MDR. and EC); German José Carreras Leukaemia Foundation (Grant 11R/2016 and 03R/2019 to MDR. and EC); [...]. We would like to thank the Proteomics unit staff (CCIT, University of Barcelona) for their support in the proteomic assay performance and analysis, and to the Primary Hemostasis laboratory group for their technical support. We also acknowledge the collaboration of Dr Josep Maria Cruzado of Institut d'Hemodiàlisi Barcelona who collaborated in obtaining the blood samples, the staff of the Maternitat Hospital, in Barcelona, for providing the umbilical cords that made possible some of the current results and to Shook Studio for the visual abstract design.Endothelial dysfunction is an earlier contributor to the development of atherosclerosis in chronic kidney disease (CKD), in which the role of epigenetic triggers cannot be ruled out. Endothelial protective strategies, such as defibrotide (DF), may be useful in this scenario. We evaluated changes induced by CKD on endothelial cell proteome and explored the effect of DF and the mechanisms involved. Human umbilical cord vein endothelial cells were exposed to sera from healthy donors (n = 20) and patients with end-stage renal disease on haemodialysis (n = 20). Differential protein expression was investigated by using a proteomic approach, Western blot and immunofluorescence. HDAC1 and HDAC2 overexpression was detected. Increased HDAC1 expression occurred at both cytoplasm and nucleus. These effects were dose-dependently inhibited by DF. Both the HDACs inhibitor trichostatin A and DF prevented the up-regulation of the endothelial dysfunction markers induced by the uraemic milieu: intercellular adhesion molecule-1, surface Toll-like receptor-4, von Willebrand Factor and reactive oxygen species. Moreover, DF down-regulated HDACs expression through the PI3/AKT signalling pathway. HDACs appear as key modulators of the CKD-induced endothelial dysfunction as specific blockade by trichostatin A or by DF prevents endothelial dysfunction responses to the CKD insult. Moreover, DF exerts its endothelial protective effect by inhibiting HDAC up-regulation likely through PI3K/AKT

La presencia del psicoanálisis en la universidad nacional de colombia

Este documento hace parte del Proyecto para la creación del Departamento de Psicoanálisis al interior de la Facultad de Ciencias Humanas de la Universidad Nacional de Colombia, Sede Bogotá y se constituye en el resultado de una investigación emprendida por el Grupo de Psicoanálisis sobre el lugar del Psicoanálisis en la Universidad. Esta investigación nace por los efectos generados del hecho de haber sido ubicado el Psicoanálisis como un enfoque psicológico en el Plan de estudios de la carrera de Psicología

Phenological Study of 53 Spanish Minority Grape Varieties to Search for Adaptation of Vitiviniculture to Climate Change Conditions

The main phenological stages (budburst, flowering, veraison, and ripeness) of 53 Spanish minority varieties were studied to determine their potential to help winegrowers adapt to climate change conditions. In total, 43 varieties were studied in the same location in Spain (Alcalá de Henares, in the Madrid region) and 10 varieties in 5 other regions (Galicia, Navarre, Catalonia, Extremadura, and Andalusia). Other traits of agronomic and oenological interest, such as yield and acidity, were also monitored. The results allow for the grouping of the varieties into several clusters according to the time of ripeness (very early—only for red varieties—and early, intermediate, and late, for both red and white varieties) and yield (high, medium, and low). The total acidity in the grape juice ranged from 3 to 11 g of tartaric acid/L. The average temperatures were higher (up to 3–4 °C during summer) compared to historical averages during the 1957–2021 time period. Advanced phenology phases and reduced acidity are regarded as negative effects of climate change for winegrowing practices. Since some minority varieties showed late or intermediate ripening, high acidity, and high (1 Kg/shoot) or medium (0.5 Kg/shoot) yield, our findings suggest that they may be cultivated in the coming years by winegrowers as an approach to mitigate climate change effects.info:eu-repo/semantics/publishedVersio

Hepatitis C virus infection acquired in childhood

Hepatitis C virus (HCV) infection occurs less frequently in children than in adult patients, and the natural history, prognosis, and clinical significance of HCV infection in children are poorly defined. We report here a descriptive follow-up of the clinical course, biochemical data, and viral markers observed in 37 children with anti-HCV. Ten patients included in the study tested persistently negative for serum HCV-RNA (group 1) and 27 patients tested persistently positive (group 2). In group 1, serum alanine aminotransferase (ALT) was normal in all patients, while two patients had non-organ-specific autoantibodies. In group 2, serum ALT was elevated in 13 of 27 patients, and five patients had non-organ-specific autoantibodies. HCV genotype 1a and 1b were the most prevalent among HCV-RNA-positive patients. Twenty liver biopsies were carried out on 17 patients in our series (mean evolution time, 11.2 years; range, 3–21 years). The liver specimens showed mild necroinflammatory changes in most patients, and fibrosis was absent or low grade. Two HCV-RNA-positive patients became persistently HCV-RNA negative. Of the 26 children investigated, 7 (one in group 1, six in group 2) had a co-infection with hepatitis G virus. Conclusion Most children chronically infected with HCV were asymptomatic and presented only mild biochemical evidence of hepatic injury. Autoimmunity in the form of non-organ-specific autoantibodies was common. HCV in children induced mild changes in the liver with a low level of fibrosis and at a low rate of progression