Fracture toughness and temperature dependence of Young's modulus of a sintered albite glass

Albite glass is an important component in many ceramic compositions, often used as liquid phase during the sintering process. Nevertheless, in spite of its almost ubiquous presence in the final microstructure of these compositions, some properties such as Young's modulus or fracture toughness have not been extensively studied in literature. This paper presents an experimental study on a sintered albite glass obtained from sodium feldspar powder. The microstructure of the resultant amorphous solid was analyzed via scanning electron microscopy and X-ray diffraction. Fracture toughness was determined at room temperature from the critical stress intensity factor (KIC) with a three point bending single-edge notched test (SENB). Young's modulus and coefficient of thermal expansion (CTE) were measured as a function of the temperature. A value of CTE of 6.6 × 10− 6 °C− 1 within the temperature range 300–500 °C was found. Young's modulus values of the albite glass were within the range from 63.6 to 65.2 MPa. SENB tests revealed a fracture toughness of KIC = 0.78 ± 0.06 MPa m1/2, which is of similar value to those found for borosilicate and soda-lime glasses

Relationship between Young's modulus and temperature in porcelain tiles

A focused research was conducted on samples prepared from an industrial porcelain tile composition containing quartz, used to produce ceramic floor tiles, with the aim of evaluating the variation of fired specimens’ Young's modulus with temperature. These samples were fired in controlled laboratory conditions so that specimens with pre-existing cracks were obtained and subject to non-destructive in situ thermo-mechanical measurements (impulse excitation technique) in the 22–700 °C temperature range during heating and cooling processes in order to find evidences to explain the hysteresis phenomenon in the Young's modulus versus temperature curve. The observed irreversible Young's modulus may be directly related to the pre-existent cracks that on heating and cooling are closed and opened up respectively, changing thus the Young's modulus which is well characterized by a hysteresis cycle

Example of a blog as a research and academic toll about drawing

This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/978-3-319-58856-8_26The blog a fresh drawing everyday started in a classroom, 5 years ago, when I suggested my students doing a drawing every day. After the general answer “that is impossible”, I proposed uploading a daily drawing in the web, so they could check if it was possible. Since then, I am sketching every day and posting a “fresh” drawing at this blog, alternating them, occasionally, with some old sketches. Starting with black and white sketches, color has instinctively started being protagonist in this illustrated and personal diary that reflects my personal and academic life and the evolution of drawing on it.Postprint (published version

Recent advances in the interrelationship of vegetation and climate in Spain

Póster elaborado para el WCRP Open Science Conference celebrado en Denver del 24 al 28 de octubre de 201

SIMULAÇÃO MATEMÁTICA DO PROCESSO DE TÊMPERA EM MATERIAIS CERÂMICOS COMPOSTOS POR UMA MATRIZ VÍTREA E PARTÍCULAS CRISTALINAS DE QUARTZO

Este trabalho estuda as tensões residuais macroscópicas em compósitos de matriz cerâmica (CMC). As tensões residuais macroscópicas são provenientes de uma alta velocidade de resfriamento correspondente a um processo de têmpera (quenching). O modelo desenvolvido incorpora propriedades elásticas e viscoelásticas de materiais cerâmicos. O perfil de tensões em uma seção transversal do corpo de prova pôde ser calculado durante toda a etapa de resfriamento. Uma densa matriz vítrea de feldspato sódico foi desenvolvida para o estudo das tensões residuais, suas propriedades térmicas e mecânicas foram mensuradas. Por outro lado, partículas cristalinas de quartzo com diferentes tamanhos e frações volumétricas foram adicionadas à matriz vítrea. Os resultados mostraram que a simulação numérica se adequou aos resultados experimentais, medidos com o método de relaxação de deformações por corte incremental. Os resultados da simulação numérica mostraram que somente houve geração de tensões residuais quando o material cerâmico foi submetido a um resfriamento rápido (têmpera). Por outro lado, estudou-se também o efeito da adição de partículas cristalinas de quartzo sobre as tensões residuais. Nesse sentido, os resultados mostraram que as partículas cristalinas de quartzo provocaram um estado de tração na superfície do material durante a transição alotrópica do quartzo (573ºC). A magnitude dessa tração chegou a um valor de ~25% da resistência mecânica do material. Com isso, o desenvolvimento dessa ferramenta matemática possibilitou prever a tensão residual na superfície do material cerâmico somente conhecendo suas propriedades termomecânicas; possibilitando assim, conhecer o incremento da resistência mecânica do material para cada velocidade de resfriamento utilizada

Seguimiento de la cubierta vegetal en la península ibérica a partir de sensores de nueva generación y su interrelación con variables climáticas

Ponencia presentada en: XIII Congreso de la Asociación Española de Teledetección celebrado en Calatayud del 23 al 26 septiembre 2009.[ES]El objetivo principal del proyecto DULCINEA ha sido el desarrollo de una metodología multi-sensor para estimar parámetros biofísicos de la cubierta vegetal. La metodología desarrollada ha proporcionado estimaciones precisas de variables biofísicas de la vegetación (FVC, LAI) que han mostrado ser adecuadas para observar las variaciones inter- e intra-anuales de la cubierta en la Península Ibérica durante un periodo de 9 años (2000-2008). Los parámetros biofísicos obtenidos han permitido evaluar la vulnerabilidad de la vegetación ante condiciones ambientales extremas a nivel de la Península Ibérica. Un paso previo ha consistido en la elaboración de mapas detallados de parámetros climáticos y tipos de cubierta dominantes en la zona. Los modelos estadísticos aplicados han evidenciado una correlación significativa entre las variables biofísicas extraídas y algunas variables meteorológicas e índices de sequía operacionales. Esta interrelación es muy dependiente del tipo de cubierta y de las características climáticas de cada región. Se han encontrado correlaciones entre las anomalías de la cobertura vegetal y el SPI especialmente significativas para el caso de las regiones más secas, con valores típicos de R2 entre 0.4 y 0.7 durante los meses de Mayo y Junio.[EN]The main objective of the DULCINEA project is to provide coherent estimates of bio-physical variables such as fractional vegetation cover (FVC) and leaf area index (LAI) at regional to global scales. One of the goals of the project is to assess the potential of derived biophysical variables in the field of drought conditions monitoring. The aim was to analyse the vulnerability of natural ecosystems against the effects of climate fluctuations like drought and extreme events in the Iberian Peninsula, from the inter-correlation between the retrieved parameters and drought indices such as the Standardized Precipitation Index (SPI). The climatic disturbances affected both the growing season and the total amount of vegetation. Strong correlations have been found between SPI and satellitederived vegetation products, which are particularly significant in semi-arid regions.Este trabajo se enmarca en el proyecto DULCINEA (CGL2005-04202) y ha contado además con el soporte del proyecto ÁRTEMIS (CGL2008-00381)

Evaluation of male fertility-associated loci in a european population of patients with severe spermatogenic impairment

Funding: This work was supported by the Spanish Ministry of Economy and Competitiveness through the Spanish State Plan for Scientific and Technical Research and Innovation (ref. SAF2016-78722-R), the “Ramón y Cajal” program (ref. RYC-2014-16458), and the “Juan de la Cierva Incorporación” program (ref. IJC2018-038026-I), which include FEDER funds. SLa received support from the Spanish Ministry of Science and Innovation (grants FIS-ISCIII DTS18/00101, co-funded by FEDER funds/European Regional Development Fund (ERDF)-a way to build Europe-), and from Generalitat de Catalunya (grant 2017SGR191). AG-J was recipient of a grant from the “Plan Propio” program of the University of Granada (“Becas de Iniciación a la Investigación para estudiantes de Grado”, conv.2019). SLa is sponsored by the “Researchers Consolidation Program” from the SNS-Dpt. Salut Generalitat de Catalunya (Exp. CES09/020). JG was partially funded by FCT/MCTES, through national funds attributed to Center for Toxicogenomics and Human Health—ToxOmics (UIDB/00009/2020). PIM is supported by the FCT post-doctoral fellowship (SFRH/BPD/120777/2016), financed from the Portuguese State Budget of the Ministry for Science, Technology and High Education and from the European Social Fund, available through the Programa Operacional do Capital Humano. AML is funded by the Portuguese Government through FCT (IF/01262/2014). IPATIMUP integrates the i3S Research Unit, which is partially supported by FCT in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274).Infertility is a growing concern in developed societies. Two extreme phenotypes of male infertility are non-obstructive azoospermia (NOA) and severe oligospermia (SO), which are characterized by severe spermatogenic failure (SpF). We designed a genetic association study comprising 725 Iberian infertile men as a consequence of SpF and 1058 unaffected controls to evaluate whether five single-nucleotide polymorphisms (SNPs), previously associated with reduced fertility in Hutterites, are also involved in the genetic susceptibility to idiopathic SpF and specific clinical entities. A significant difference in the allele frequencies of USP8-rs7174015 was observed under the recessive model between the NOA group and both the control group (p = 0.0226, OR = 1.33) and the SO group (p = 0.0048, OR = 1.78). Other genetic associations for EPSTI1-rs12870438 and PSAT1-rs7867029 with SO and between TUSC1-rs10966811 and testicular sperm extraction (TESE) success in the context of NOA were observed. In silico analysis of functional annotations demonstrated cis-eQTL effects of such SNPs likely due to the modification of binding motif sites for relevant transcription factors of the spermatogenic process. The findings reported here shed light on the molecular mechanisms leading to severe phenotypes of idiopathic male infertility, and may help to better understand the contribution of the common genetic variation to the development of these conditions.publishersversionpublishe