Spalling uniaxial strength of Al2O3 at high strain rates

In this article research into the uniaxial tensile strength of Al2O3 monolithic ceramic is presented. The experimental procedure of the spalling of long bars is investigated from different approaches. This method is used to obtain the tensile strength at high strain rates under uniaxial conditions. Different methodologies proposed by several authors are used to obtain the tensile strength. The hypotheses needed for the experimental set-up are also checked, and the requirements of the set-up and the variables are also studied by means of numerical simulations. The research shows that the shape of the projectile is crucial to achieve successfully tests results. An experimental campaign has been carried out including high speed video and a digital image correlation system to obtain the tensile strength of alumina. Finally, a comparison of the test results provided by three different methods proposed by different authors is presented. The tensile strength obtained from the three such methods on the same specimens provides contrasting results. Mean values vary from one method to another but the trends are similar for two of the methods. The third method gives less scatter, though the mean values obtained are lower and do not follow the same trend as the other methods for the different specimens

Análisis sobre la influencia de la densidad en la termografía de infrarrojos y el alcance de esta técnica en la detección de defectos internos en la madera

This paper shows the results of a laboratory phase for the determination of the 1limits of infrared thermography in detecting internal defects in wood and, furthermore, it analyses how the density of this material can influence the surface temperature displayed in a thermogram. To this end, experimental work is carried out whereby a series of work and environmental parameters are monitored (such as environmental temperature, relative humidity, distance to target), and the process is systematized by using pieces of different wood species (different densities) and by devising a set of samples for which various possible cases are analysed in terms of size and internal position of the damage. Similarly, using these samples, a study has been conducted on the effect on the thermal image produced by an increase of humidity inside the defect phenomena normally associated with wood decay.En el presente artículo se muestran los resultados obtenidos en una fase de laboratorio al tratar de determinar el alcance de la termografía de infrarrojos en la detección de defectos internos en la madera y, por otro lado, cómo interviene la densidad de este material sobre la temperatura superficial mostrada en un termograma. Para ello se ha desarrollado un trabajo experimental donde se han controlado una serie de parámetros ambientales y de trabajo (temperatura ambiente, humedad relativa, distancia al objetivo…), y se ha sistematizado el proceso utilizando piezas de distintas especies de madera (distintas densidades) y diseñando una serie de probetas donde se han analizado varias casuísticas posibles en cuanto a tamaño y posición interna de los daños. Análogamente, sobre estas probetas se ha estudiado el efecto que produce sobre la imagen termográfica un incremento de humedad interna en el defecto asociada normalmente a los fenómenos de pudrición de la madera

Determinación de las características mecánicas de los muros de fábrica de ladrillo en la arquitectura doméstica sevillana de los siglos XVIII Y XIX

The main aim consists on improving the information technology tools in order to make models of the real situation (constructive, geometrical, resistant) of the structural elements, as well as getting the restoration or support proposals. We have developed the work in some stages: – Analysis,inspection, measurement, and evolution of the building. – Extraction and analysis in laboratory of small samples of masonry walls to determine the strength parameters of materials. – Experimental studie for determination of a model and obtaining the compression stresses of the masonry walls studied. – The monitoring instrumentation which has been used is an accelerograph to evaluate the rigidity of the walls. – Application of Finite Elements Method in order to obtain the stresses distribution before and after any change in the building. The final aim is to be able to compare the results from the laboratory and the stresses distribution from the F.E.M., in order to decide the best way of getting the restoration.El resultado del trabajo permite manejar datos geométricos, constructivos y mecánicos objetivos en el momento de la recuperación de los muros estudiados y los edificios referidos. Las fases seguidas para el desarrollo del método han sido: – Análisis de edificios objeto de rehabilitación: características constructivas del muro a estudiar, levantamiento de lesiones. – Extracción y análisis en laboratorio de pequeñas muestras de la fábrica para la determinación de las características resistentes de sus materiales. – Trabajo experimental en laboratorio para elaboración de un modelo que permita la obtención de la resistencia a compresión de la fábrica estudiada. – Aplicación del acelerógrafo para medir la rigidez del edificio in situ, aproximándonos al módulo de elasticidad del muro de fábrica. – Obtención de conclusiones con la comparación de valores máximos de tensiones obtenidos para una fábrica no fisurada mediante un Análisis de Elementos Finitos, con los valores obtenidos de resistencia en los estudios anteriores. Esta comparación permitirá decidir el comportamiento de los muros ante la restauración

Caracterización de morteros con cerámica reciclada y su uso en piezas prefabicadas para entrevigado de forjados

This study analyses a procedure to manufacture mortars with different percentages of ceramic waste as partial replacement for aggregates. The study also examines the physical, chemical and mechanical properties of the new mortars, analysing substitution ratios that range from 10% to 50%. Prior to this, all the materials used in the production of the mortar were characterised using X-ray diffraction (XRD) and fluorescence (XRF). The objective was to determine the similarity between different types of ceramic waste, as well as the differences in the minerology and chemical composition with the aggregate. The results of the study show that it is possible to obtain mortars with lower densities compared to the same product with no recycled content. The product’s characteristics make it ideal for the manufacture of prefabricated components for structural floors for rehabilitation works. Finally, the pieces are used in a real rehabilitation case study, highlightining the structural advantages.Este trabajo analiza morteros con diferentes porcentajes de cerámica reciclada como sustituto parcial de la arena. Además el estudio examina las propiedades físicas, químicas y mecánicas de los nuevos morteros, empleando diferentes porcentajes de sustitución (10% - 50%). Con anterioridad, se caracterizaron todos los materiales empleados en este trabajo mediante difracción y fluorescencia de rayos-X. El objetivo fue determinar las diferencias y similitudes en la composición química y mineralógica de los distintos tipos de residuos cerámicos y del resto de áridos utilizados. Los resultados muestran que es posible obtener morteros con menor densidad frente a las muestras sin contenido reciclado. Sus características los hacen idóneos para la creación de piezas prefabricadas de entrevigado para rehabilitación de forjados. Finalmente. Las piezas se usaron en un caso de estudio real, destacando las ventajas estructurales que conlleva su uso

Análisis sobre la influencia de la densidad en la termografía de infrarrojos y el alcance de esta técnica en la detección de defectos internos en la madera

This paper shows the results of a laboratory phase for the determination of the 1limits of infrared thermography in detecting internal defects in wood and, furthermore, it analyses how the density of this material can influence the surface temperature displayed in a thermogram. To this end, experimental work is carried out whereby a series of work and environmental parameters are monitored (such as environmental temperature, relative humidity, distance to target), and the process is systematized by using pieces of different wood species (different densities) and by devising a set of samples for which various possible cases are analysed in terms of size and internal position of the damage. Similarly, using these samples, a study has been conducted on the effect on the thermal image produced by an increase of humidity inside the defect phenomena normally associated with wood decay.<br><br>En el presente artículo se muestran los resultados obtenidos en una fase de laboratorio al tratar de determinar el alcance de la termografía de infrarrojos en la detección de defectos internos en la madera y, por otro lado, cómo interviene la densidad de este material sobre la temperatura superficial mostrada en un termograma. Para ello se ha desarrollado un trabajo experimental donde se han controlado una serie de parámetros ambientales y de trabajo (temperatura ambiente, humedad relativa, distancia al objetivo…), y se ha sistematizado el proceso utilizando piezas de distintas especies de madera (distintas densidades) y diseñando una serie de probetas donde se han analizado varias casuísticas posibles en cuanto a tamaño y posición interna de los daños. Análogamente, sobre estas probetas se ha estudiado el efecto que produce sobre la imagen termográfica un incremento de humedad interna en el defecto asociada normalmente a los fenómenos de pudrición de la madera

Anthropogenic and natural CO2 exchange through the Strait of Gibraltar

The exchange of both anthropogenic and natural inorganic carbon between the Atlantic Ocean and the Mediterranean Sea through Strait of Gibraltar was studied for a period of two years under the frame of the CARBOOCEAN project. A comprehensive sampling program was conducted, which was design to collect samples at eight fixed stations located in the Strait in successive cruises periodically distributed through the year in order to ensure a good spatial and temporal coverage. As a result of this monitoring, time series namely GIFT (GIbraltar Fixed Time series) has been established, allowing the generation of an extensive data set of the carbon system parameters in the area. Data acquired during the development of nine campaigns were analyzed in this work. Total inorganic carbon concentration (CT ) was calculated from alkalinity-pHT pairs and appropriate thermodynamic relationships, with the concentration of anthropogenic carbon (CANT) being also computed using two methods, the 1C* and the TrOCA approach. Applying a two-layer model of water mass exchange through the Strait and using a value of −0.85 Sv for the average transport of the outflowing Mediterranean water recorded in situ during the considered period, a net export of inorganic carbon from the Mediterranean Sea to the Atlantic was obtained, which amounted to 25±0.6 TgC yr−1. A net alkalinity output of 16±0.6 TgC yr−1 was also observed to occur through the Strait. In contrast, the Atlantic water was found to contain a higher concentration of anthropogenic carbon than the Mediterranean water, resulting in a net flux of CANT towards the Mediterranean basin of 4.20±0.04 TgC yr−1 by using the 1C* method, which constituted the most adequate approach for this environment. A carbon balance in the Mediterranean was assessed and fluxes through the Strait are discussed in relation to the highly diverse estimates available in the literature for the area and the different approaches considered for CANT estimation. This work unequivocally confirms the relevant role of the Strait of Gibraltar as a controlling point for the biogeochemical exchanges occurring between the Mediterranean Sea and the Atlantic Ocean and emphasizes the influence of the Mediterranean basin in the carbon inventories of the North Atlantic.Peer reviewe

Matched cohort study on the efficacy of tocilizumab in patients with COVID-19

Background: Tocilizumab has been proposed as a treatment for the new disease COVID-19, however, there is not enough scientific evidence to support this treatment. The objective of this study is to analyze whether the use of tocilizumab is associated with respiratory improvement and a shorter time to discharge in patients with COVID-19 and lung involvement. Methods: Observational study on a cohort of 418 patients, admitted to three county hospitals in Catalonia (Spain). Patients admitted consecutively were included and followed until discharge or up to 30 days of admission. A sub-cohort of patients treated with tocilizumab and a sub-cohort of control patients were identified, matched by a large number of risk factors and clinical variables. Sub-cohorts were also matched by the number of other treatments for COVID-19 that patients received. Increment in SAFI (inspired oxygen fraction / saturation) 48 h after the start of treatment, and time to discharge, were the primary outcomes. Mortality, which was a secondary outcome, was analyzed in the total cohort, by using logistic regression models, adjusted by confounders. Results: There were 96 patients treated with tocilizumab. Of them, 22 patients could be matched with an equivalent number of control patients. The increment in SAFI from baseline to 48 h of treatment, was not significantly different between groups (tocilizumab: −0.04; control: 0.09; p = 0.636). Also, no difference in time to discharge was found between the two sub-cohorts (logrank test: p = 0.472). The logistic regression models, did not show an effect of tocilizumab on mortality (OR 0.99; p = 0.990). Conclusions: We did not find a clinical benefit associated with the use tocilizumab, in terms of respiratory function at 48 h of treatment, or time to discharge

Scutoids are a geometrical solution to three-dimensional packing of epithelia

As animals develop, tissue bending contributes to shape the organs into complex three-dimensional structures. However, the architecture and packing of curved epithelia remains largely unknown. Here we show by means of mathematical modelling that cells in bent epithelia can undergo intercalations along the apico-basal axis. This phenomenon forces cells to have different neighbours in their basal and apical surfaces. As a consequence, epithelial cells adopt a novel shape that we term “scutoid”. The detailed analysis of diverse tissues confirms that generation of apico-basal intercalations between cells is a common feature during morphogenesis. Using biophysical arguments, we propose that scutoids make possible the minimization of the tissue energy and stabilize three-dimensional packing. Hence, we conclude that scutoids are one of nature's solutions to achieve epithelial bending. Our findings pave the way to understand the three-dimensional organization of epithelial organs

Inspección mediante técnicas no destructivas de un edificio histórico: oratorio San Felipe Neri (Cádiz)

The main aim of this article is showing the results that have been obtained when non destructive techniques (ultrasound and thermography) are applied to a building with an important artistic and historical value. These non-destructive techniques have been applied in the inspection of the wooden roof structure to detect different states of deterioration, loss of density and defects. The aim is the assessment the state of the preservation of the wooden structure. A fieldwork has been carried out, where the two techniques have been applied together, ultrasound, an effective technique to establish the diagnosis of a wooden structure, and the thermography, a technique less tested in the in situ inspection of this material. The aim is checking the range and the real possibilities of using of each technique. In this sense, the methodology of ultrasound developed and published by the authors is applied and the thermography like in situ inspection tool, analysing additional difficulties and interference parameters not found in laboratory. The conclusions of this study show that the union of the ultrasound technique and the thermography is a good tool for on-site inspection of wooden structures and to assess their conditions allowing establishing a proper diagnosis. Thermography can detect different moisture contents and different materials and, on the other hand, ultrasound detects different states of deterioration or loss of density in specific areas with a high moisture content of the pieces.El objetivo de este artículo es dar a conocer los resultados obtenidos al aplicar técnicas no destructivas de inspección (ultrasonidos y termografía) durante las obras de reparación de un edificio de gran valor histórico y artístico. Estas técnicas no destructivas se han aplicado en la inspección de la cubierta de madera del edificio para detectar distintos estados de deterioro, pérdidas de densidad y defectos, con el objetivo de evaluar su estado de conservación. Se ha realizado un trabajo de campo donde se ha aplicado ambas técnicas conjuntamente, los ultrasonidos, técnica eficaz para establecer el diagnóstico de una estructura de madera, y la termografía, técnica menos experimentada en la inspección in situ de este material. El objetivo es acotar el alcance y las posibilidades reales de utilización de cada una de las técnicas. En este sentido, se aplica la metodología de ultrasonidos desarrollada y publicada por las autoras y se estudia la termografía como herramienta de inspección in situ analizando las dificultades añadidas y parámetros de interferencia no detectados en laboratorio. Las conclusiones del trabajo ponen de manifiesto que la unión de la técnica de ultrasonidos y la termografía constituyen una buena herramienta para la inspección in situ de las estructuras de madera y para evaluar sus condiciones permitiendo establecer un diagnóstico adecuado. La termografía permite detectar distintos contenidos de humedad y distintos materiales y, por otro lado, los ultrasonidos los distintos grados de deterioro o pérdida de densidad en zonas localizadas con elevado contenido de humedad de las piezas

Identification of Interleukin-27 (IL-27)/IL-27 Receptor Subunit Alpha as a Critical Immune Axis for In Vivo HIV Control

Intact and broad immune cell effector functions and specific individual cytokines have been linked to HIV disease outcome, but their relative contribution to HIV control remains unclear. We asked whether the proteome of secreted cytokines and signaling factors in peripheral blood can be used to discover specific pathways critical for host viral control. A custom glass-based microarray, able to measure >600 plasma proteins involved in cell-to-cell communication, was used to measure plasma protein profiles in 96 HIV-infected, treatment-naive individuals with high (>50,000) or low (600 soluble proteins, our data highlight the importance of Th17 cells and Wnt/β-catenin signaling in HIV control and especially identify the IL-27/IL-27 receptor subunit alpha (IL-27RA) axis as a predictor of plasma viral load and proviral copy number in the peripheral blood. These data may provide important guidance to therapeutic approaches in the HIV cure agenda