Estudio del carbonato de litio como ayuda de sinterización para óxido de estaño" mediante diseños" de experimentos: variables principales y cambios microestructurales

[ES] El óxido de estaño es uno de los materiales más estudiados, dado su extenso campo de aplicación. De entre sus propiedades, cabe destacar su alta conductividad eléctrica y su resistencia a la corrosión, de ahí que entre sus aplicaciones se encuentre la de electrodo cerámico. Sin embargo, su baja capacidad de densificación dificulta su uso. Como consecuencia, se requieren técnicas avanzadas o aditivos de sinterización que faciliten la obtención de piezas con baja porosidad. Hasta el momento han sido muchos los aditivos estudiados, CaCO3, Co3O4, Nb2O5 o MnO2, entre otros. En este trabajo se estudia el proceso de sinterización de piezas de SnO2 a las que se ha incorporado Li2CO3 como aditivo de sinterización, el cual genera una fase líquida, por ser uno de los aditivos en cuyo estudio se ha profundizado en menor medida. A través de diseños factoriales de experimentos 2n, se han determinado los efectos de los diferentes parámetros del ciclo de cocción (temperatura máxima, velocidad de calentamiento y tiempo de permanencia), así como la cantidad de aditivo de sinterización, sobre la evolución de la contracción volumétrica. Los resultados muestran que la incorporación del carbonato de litio, en porcentajes superiores al 1% molar, no es favorable para la densificación. Respecto a los parámetros de cocción, resultan recomendables tratamientos térmicos a elevada temperatura (1.300 °C) con tiempos de permanencia moderados (1 hora), mientras que la velocidad de calentamiento ejerce una menor influencia. En estas condiciones se obtiene una microestructura de poros cerrados y redondeados, en la que queda encerrada una fase residual cuya reducida proporción impide su caracterización.[EN] Tin oxide is one of the most extensively studied semiconductor materials due to its broad field of applications. On the one hand, its high conductivity and its corrosion resistance are the most remarkable properties. Therefore, one of the most developed uses in the recent decades has been as ceramic electrode for electrooxidation process. On the other hand, its poor sinterability hinders a broader use. As a result, the use of advanced techniques or sin-tering aids for obtaining low-porosity specimens is necessary. So far, many additives have been studied, CaCO3, Co3O4, Nb2O5 or MnO2, among others. In the present work, the sinter-ing behaviour of SnO2-based powder, containing Li2CO3 as a sintering aid, which generates a liquid phase, has been analysed, since it is one of the additives that has been studied to a lesser extent. The effect of the amount of sintering aid just like the thermal treatment parameters (maximum temperature, heating rate and soaking time) on volumetric contrac-tion's evolution has been studied through a factorial experiment designs 2n. The results show that an amount of lithium carbonate greater than 1 mol.% is unfavourable to densification. With regards to the thermal cycle's parameters, it is advisable to have thermal treatments at high temperatures (1300 degrees C) with moderate soaking times (1 h), as maximum temperatures have the biggest influence on the densification followed by soaking time while the heating rate has a lesser influence. Under these conditions, a microstructure of closed and rounded pores is obtained, in which a residual phase is enclosed, but the small proportion of which prevents its characterisation.The authors of this paper would like to thank the Ministry of Economy and Competitiveness and the European Regional Development Fund for supporting this research [Plan Nacional de I+D, project Ref. CTQ2015-65202-C2-2-R (MINECO/FEDER)] .Sánchez-Rivera, M.; Orts, MJ.; Pérez-Herranz, V.; Mestre, S. (2023). Study of lithium carbonate as sintering aid for tin oxide densification trough experimental designs: Main variables and microstructure changes. Boletín de la Sociedad Española de Cerámica y Vidrio. 62(2):194-202. https://doi.org/10.1016/j.bsecv.2022.04.00319420262

Composition, spatial distribution and sources of macro-marine litter on the Gulf of Alicante seafloor (Spanish Mediterranean)

The composition, spatial distribution and source of marine litter in the Spanish Southeast Mediterranean were assessed. The data proceed from a marine litter retention programme implemented by commercial trawlers and were analysed by GIS. By weight, 75.9% was plastic, metal and glass. Glass and plastics were mainly found close to the coast. A high concentration of metal was observed in some isolated zones of both open and coastal waters. Fishing activity was the source of 29.16% of the macro-marine litter, almost 68.1% of the plastics, and 25.1% of the metal. The source of the other 60.84% could not be directly identified, revealing the high degree of uncertainty regarding its specific origin. Indirectly however, a qualitative analysis of marine traffic shows that the likely sources were merchant ships mainly in open waters and recreational and fishing vessels in coastal waters.We are grateful for the support of the PESCAL Project by European funds through General Secretary of Fisheries of Spain, led by CETMAR with the participation of the Joint Research Unit between the Spanish Oceanography Institute (IEO) and the University of Alicante (UA). Santiago García-Rivera was supported by PESCAL Project and a PhD grant from the University of Alicante

Estudio del carbonato de litio como ayuda de sinterización para óxido de estaño mediante diseños de experimentos: variables principales y cambios microestructurales

Tin oxide is one of the most extensively studied semiconductor materials due to its broad field of applications. On the one hand, its high conductivity and its corrosion resistance are the most remarkable properties. Therefore, one of the most developed uses in the recent decades has been as ceramic electrode for electrooxidation process. On the other hand, its poor sinterability hinders a broader use. As a result, the use of advanced techniques or sin- tering aids for obtaining low-porosity specimens is necessary. So far, many additives have been studied, CaCO3, Co3O4, Nb2O5 or MnO2, among others. In the present work, the sinter- ing behaviour of SnO2-based powder, containing Li2CO3 as a sintering aid, which generates a liquid phase, has been analysed, since it is one of the additives that has been studied to a lesser extent. The effect of the amount of sintering aid just like the thermal treatment parameters (maximum temperature, heating rate and soaking time) on volumetric contrac- tion’s evolution has been studied through a factorial experiment designs 2n. The results show that an amount of lithium carbonate greater than 1 mol.% is unfavourable to densification. With regards to the thermal cycle’s parameters, it is advisable to have thermal treatments at high temperatures (1300 ◦C) with moderate soaking times (1 h), as maximum temperatures have the biggest influence on the densification followed by soaking time while the heating rate has a lesser influence. Under these conditions, a microstructure of closed and rounded pores is obtained, in which a residual phase is enclosed, but the small proportion of which prevents its characterisation.El óxido de esta ̃no es uno de los materiales más estudiados, dado su extenso campo de aplicación. De entre sus propiedades, cabe destacar su alta conductividad eléctrica y su resistencia a la corrosión, de ahí que entre sus aplicaciones se encuentre la de electrodo cerámico. Sin embargo, su baja capacidad de densificación dificulta su uso. Como con- secuencia, se requieren técnicas avanzadas o aditivos de sinterización que faciliten la obtención de piezas con baja porosidad. Hasta el momento han sido muchos los aditivos estudiados, CaCO3, Co3O4, Nb2O5 o MnO2, entre otros. En este trabajo se estudia el proceso de sinterización de piezas de SnO2 a las que se ha incorporado Li2CO3 como aditivo de sinterización, el cual genera una fase líquida, por ser uno de los aditivos en cuyo estudio se ha profundizado en menor medida. A través de dise ̃nos factoriales de experimentos 2n, se han determinado los efectos de los diferentes parámetros del ciclo de cocción (temper- atura máxima, velocidad de calentamiento y tiempo de permanencia), así como la cantidad de aditivo de sinterización, sobre la evolución de la contracción volumétrica. Los resulta- dos muestran que la incorporación del carbonato de litio, en porcentajes superiores al 1% molar, no es favorable para la densificación. Respecto a los parámetros de cocción, resul- tan recomendables tratamientos térmicos a elevada temperatura (1.300 ◦C) con tiempos de permanencia moderados (1 hora), mientras que la velocidad de calentamiento ejerce una menor influencia. En estas condiciones se obtiene una microestructura de poros cerrados y redondeados, en la que queda encerrada una fase residual cuya reducida proporción impide su caracterización

Actualidad editorial de la historia conceptual

El artículo se incluye dentro de la revista en un dossier titulado 'Filosofía de la historia e historia conceptual II'. En consonancia con este epígrafe y bajo el lema de 'Actualidad editorial de la historia conceptual' se agrupan varias reseñas de publicaciones centradas en esta disciplina. En primer lugar, Lorena Rivera León se ocupa del monográfico 'Teoría y práctica de la historia conceptual' publicado por la revista 'Isegoría', nº 37 (2007), así como del volumen 'Teorías y prácticas de la historia conceptual' compilado por Faustino Oncina Coves y aparecido en CSIC-Plaza y Valdés en 2008. En segundo término, María G. Navarro presta atención a 'Conceptos. Revista de investigación graciana', nº 5 (2008). Por último, José Manuel Sánchez Fernández se detiene en el libro 'Historia conceptual, Ilustración y modernidad', escrito por Faustino Oncina Coves, que vio la luz en la editorial Anthropos en 2009

A simple approximation for the evaluation of the photon isoeffective dose in Boron Neutron Capture Therapy based on dose-independent weighting factors

The current methodology for determining the biological effect of Boron Neutron Capture Therapy (BNCT) has recently been questioned, and a more accurate framework based in the photon isoeffective dose has been proposed. In this work we derive a first order approximation to this quantity than can be easily evaluated even from limited data, as is the current situation in the radiobiology of BNCT. This procedure removes the main drawbacks of the current method and it is based on new weighting factors that, as a difference with the previously used, are true constants (dose independent). In addition to this, we apply the formalism to allow the comparison to a fractionated conventional radiotherapy treatment, for which there is a lot of knowledge from clinical practice. As an application, the photon isoeffective dose of a BNCT treatment for a brain tumor is estimated. An excel sheet used for these calculations is also provided as supplementary material and can be used also with user-provided input data for the estimation of the photon isoeffective dose for comparison with conventional radiotherapy, both to single and fractionated treatments.Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, Granada, Spain. Institut Laue-Langevin. Grenoble, Rhône-Alpes, France. Departamento de Bioquímica y Biología Molecular III e Inmunología, Universidad de Granada, Granada, Spai

Dancing toward Well-Being: Effects on Mood and Well-Being of a 12-Week Flamenco Dance Workshop in Women Aged 60–80 Years

The objective of this study was to examine the effect of a flamenco dance program on the mood and subjective well-being of 34 self-selected women from the community, aged between 62 and 79 years. The mean age was 70.11 (SD = 5.13). Participants voluntarily enrolled in a 12-week flamenco dance workshop conducted by the Autoestima Flamenca Association, with one two-hour session per week. Every two weeks, mood measurements (sadness, anxiety, anger and joy) were taken, and subjective well-being assessments were conducted before and after each session. It was found that the participants’ overall mood and subjective well-being improved significantly following the intervention. These improvements were observed at both the individual and group levels. Overall, our findings suggest that participation in a free 12-week flamenco dance program had a positive impact on mood and subjective well-being in this segment of the population.Junta de Andalucía SEJ-45

Neutron radiobiology studies with a pure cold neutron beam

Data on the radiobiological effects of thermal neutrons are usually obtained from irradiations in a mixed field of neutrons of different energies and gamma rays or from conversion of proton data with similar energies to those created in the neutron capture on nitrogen. Experimental data from irradiations in a pure thermal or cold neutron beam can help to find new values for neutron relative biological effectiveness (RBE) factors, which are useful for BNCT (Boron Neutron Capture Therapy) and radiation protection applications. We present a new experimental setup for radiobiological studies at a cold neutron beam at Institut Laue-Langevin, a beam without fast neutron component and almost no gamma ray contribution. After the irradiation, survival assays are performed to obtain the survival curves. Finally, comparing with a reference photon irradiation, the thermal neutron RBE factors can be calculated. The methodology is outlined at the example of A375 melanoma cells for which new radiobiological data were obtained.We acknowledge financial support for this work from the Fundación Científica de la Asociación Española Contra el Cáncer (AECC) under grant PS16163811PORR, Junta de Andalucía (Andalusian Regional Government), under contract P11-FQM-8229, Spanish MINECO and FEDER funds under contract FIS2015-69941-C2-1-P, the grant agreement ILL-UGR and the founders of the University of Granada Chair Neutrons for Medicine: Spanish Fundación ACS and Capitán Antonio. M.P. acknowledges a grant under the program Becas de Iniciación a la Investigación from the Universidad de Granada (Plan Propio de Investigación). The open access fee was covered by FILL2030, a European Union project within the European Commission’s Horizon 2020 Research and Innovation programme under grant agreement N°731096

Explorando el uso de las Tecnologías de la información y la comunicación y las redes sociales entre el profesorado universitario de enfermería. Una encuesta de opinión

[EN] Objective. This work sought to analyze the use of Information and Communication Technologies (ICTs) and social networks among the university nursing faculty staff in Spain. Methodology. This was a descriptive, cross-sectional study using a questionnaire on ICT skills designed to comply with the research objective, which was evaluated by experts and which was subjected to exploratory analysis of principal components; the reliability of this instrument measured with Cronbach’s alpha was 0.85. The information technology tool used to publish the questionnaire on line was Limesurvey. The sample comprised 165 professors from 25 Nursing Faculties and Schools from universities in Spain. Results. Seventy one percent of the total surveyed used internet services to look for information, 63% used the internet as a means for formation and learning, and 72% used it as a communication platform (e-mail and virtual platforms like Sakai and Moodle). Although 51% of the teaching staff surveyed had more than 120 students registered in their courses, hypothesis testing revealed that the number of students in class is not a determining factor for the teaching staff to have greater interest to update its knowledge in ICTs. Younger professors use new technologies more profusely and the most-valued advantage of using ICTs was quick access to information. Professors perceive that after the Bologna Declaration, which requires modifying their teaching-learning processes through the new teaching methodologies, a drop has been produced in their performance and that of their peers in their area of knowledge. Conclusion. The nursing teaching staff is making strong efforts to confront the new challenges posed by ICTs to train the professionals of the 21st century. It is fundamental to pay special attention to improving the university teaching staff’s skills in managing ICTs, promoting the implementation of the knowledge acquired.[ES] Objetivo. Analizar el uso de las Tecnologías de la información y la comunicación –TIC- y las redes sociales entre el profesorado universitario de enfermería en España. Metodología. Estudio descriptivo de corte transversal en el que se empleó un cuestionario sobre competencias TIC diseñado para cumplir con el objetivo de investigación, el cual fue evaluado por expertos. Posteriormente, se le hizo análisis exploratorio de componentes principales. La confiabilidad de este instrumento fue 0.85, medida con el alfa de Cronbach. La herramienta informática utilizada para publicar en línea el cuestionario fue Limesurvey. La muestra estuvo compuesta por 165 profesores de 25 Facultades y Escuelas de Enfermería de las Universidades de España. Resultados. El 71% del total de encuestados utilizaba los servicios de Internet para buscar información, el 63% hacía uso de Internet como vía de formación y aprendizaje y un 72% lo empleaba como plataforma de comunicación (correo electrónico y plataformas virtuales como Sakai y Moodle). A pesar de que el 51% del profesorado encuestado tenía más de 120 alumnos matriculados en sus cursos, un contraste de hipótesis reveló que el número de alumnos en clase no es un factor determinante para que el profesorado tenga mayor interés por actualizar sus conocimientos en TIC. Los profesores más jóvenes utilizan con mayor profusión las nuevas tecnologías y la ventaja más valorada del uso de las TIC fue el acceso rápido a la información. Los profesores perciben que tras la Declaración de Bolonia, que exige modificar sus procesos de enseñanza aprendizaje mediante las nuevas metodologías docentes, se ha producido un descenso en el rendimiento propio y en el de sus compañeros de área de conocimiento. Conclusión. El profesorado de enfermería está afrontando con esfuerzo los nuevos retos que las TIC plantean para formar a los profesionales del siglo XXI. Es fundamental prestar especial atención al mejoramiento de las competencias en manejo de TIC del profesorado universitario, impulsando la puesta en práctica de los conocimientos adquiridos.[PT] Objetivo. Analisar o uso das Tecnologias da informação e a comunicação –TICs- e as redes sociais entre o professorado universitário de enfermagem na Espanha. Metodologia. Estudo descritivo de corte transversal no que se empregou um questionário sobre concorrências TICs desenhado para cumprir com o objetivo de investigação, o qual foi avaliado por experientes e ao que posteriormente se lhe fez análise exploratório de componentes principais; a confiabilidade deste instrumento medida com o alfa de Cronbach foi 0.85. A ferramenta informática utilizada para publicar na linha o questionário foi Limesurvey. A amostra esteve composta por 165 professores de 25 Faculdades e Escolas de Enfermagem das Universidades da Espanha. Resultados. 71% do total de interrogados utilizava os serviços de Internet para procurar informação, 63% fazia uso de internet como via de formação e aprendizagem e um 72% o empregava como plataforma de comunicação (correio eletrônico e plataformas virtuais como Sakai e Moodle). Apesar de que 51% do professorado interrogado tinha mais de 120 alunos matriculados em seus cursos, um contraste de hipótese revelou que o número de alunos em classe não é um fator determinante para que o professorado tenha maior interesse por atualizar seus conhecimentos em TICs. Os professores mais jovens utilizam com maior profusão as novas tecnologias e a vantagem mais valorizada do uso das TICs foi o acesso rápido à informação. Os professores percebem que depois da Declaração de Bologna, que exige modificar seus processos de ensino-aprendizagem mediante as novas metodologias docentes, produziu-se um descenso no endimento próprio e no de seus colegas da área de conhecimento. Conclusão. O professorado de enfermagem está enfrentado com esforço os novos reptos que as TICs propõem para formar aos profissionais do século XXI. É fundamental prestar especial atendimento ao melhoramento as concorrências em manejo de TICs do professorado universitário, impulsionando a posta em prática dos conhecimentos adquiridos.S

Research about the pozzolanic activity of waste materials from calcined clay

[EN]To recycle and reutilise waste materials and find definite applications for their use, it is necessary to have a deep knowledge of them. The aim of this study is to study the possibility of using waste materials from calcined clay, actually ceramic tile, once crushed and grounded, as pozzolanic material. For this purpose, different tests are carried out in order to establish the pozzolanic activity of this material. At the same time, these results are compared to those of other industrial by-products, fly ash and silica fume, which are pozzolanic materials usually employed to elaborate mortars and concretes.[ES] Para llevar a cabo labores encaminadas al reciclado y revalorización de residuos es necesario un conocimiento profundo de los mismos, de forma que se busquen aplicaciones concretas de uso. El objetivo de este estudio es investigar la posibilidad de utilizar materiales de desecho procedentes de arcilla cocida, concretamente teja cerámica, una vez triturada y molida, como puzolana. Para ello, se efectúan diferentes ensayos dirigidos a establecer la actividad puzolanica del material. A su vez, estos resultados son comparados con otros residuos industriales, ceniza volante y humo de sílice, habituales en la elaboración de morteros y hormigones.Peer reviewe

Life Cycle Assessment of Cement Production with Marble Waste Sludges

The construction industry has a considerable environmental impact in societies, which must be controlled to achieve adequate sustainability levels. In particular, cement production contributes 5–8% of CO2 emissions worldwide, mainly from the utilization of clinker. This study applied Life Cycle Assessment (LCA) methodology to investigate the environmental impact of cement production and explore environmental improvements obtained by adding marble waste sludges in the manufacture of Portland cement. It was considered that 6–35% of the limestone required for its production could be supplied by marble waste sludge (mainly calcite), meeting the EN 197-1:2011 norm. Energy consumption and greenhouse gas (GHG) emission data were obtained from the Ecovent database using commercial LCA software. All life cycle impact assessment indicators were lower for the proposed “eco-cement” than for conventional cement, attributable to changes in the utilization of limestone and clinker. The most favorable results were achieved when marble waste sludge completely replaced limestone and was added to clinker at 35%. In comparison to conventional Portland cement production, this process reduced GHG emissions by 34%, the use of turbine waters by 60%, and the emission of particles into the atmosphere by 50%. Application of LCA methodology allowed evaluation of the environmental impact and improvements obtained with the production of a type of functional eco-cement. This approach is indispensable for evaluating the environmental benefits of using marble waste sludges in the production of cement.Junta de Andalucía and Fondo Europeo de Desarrollo Regional (FEDER) Ref. P18-RT-419