Internal friction associated with ε martensite in shape memory steels produced by casting route and through additive manufacturing: Influence of thermal cycling on the martensitic transformation

Among the different families of shape memory alloys (SMA), the Fe-Mn-Si-Cr-Ni alloys have attracted a renewed interest because of its low cost, high corrosion resistance and high recovery strength during the shape memory effect, and the new technologies of additive manufacturing offer unforeseen possibilities for this family of SMA. In the present work, the reversible gamma - epsilon martensitic transformation (MT), responsible for the shape memory effect, is studied in two Fe-Mn-Si-Cr-Ni alloys with high (20.2 wt%) and low (15.8 wt%) Mn content, produced by the conventional route of casting and rolling, in comparison with the MT in another similar alloy, with intermediate Mn content (19.4 wt%), which was produced by gas atomization and additive manufacturing through laser metal deposition. The forward and reverse gamma - epsilon MT is studied by mechanical spectroscopy through the internal friction spectra and the dynamic modulus variation, together with a parallel microstructural characterization including in-situ observation of the gamma - epsilon MT during cooling and heating at the scanning electron microscope. The evolution of the transformed fraction of epsilon martensite, evaluated through the integral area of the internal friction peak, was followed along thermal cycling in all three alloys. Both, the internal friction and the electron microscopy studies show that the epsilon martensite amount increases very fast during the first few cycles, and then decreases with a tendency towards its stabilization for many tens of cycles. The results show that the gamma - epsilon MT is more stable on cycling in the additive manufactured sample than in the conventionally processed samples, opening new avenues for designing shape memory steels to be specifically processed through additive manufacturing.This work was supported by the ELKARTEK-CEMAP (KK-2020/00047) project from the Industry Department of the Basque Government, and the GIU-17/071 from the University of the Basque Country, UPV/EHU. This work made use of the SGIKER facilities at the UPV/EHU

Estrategias de estudio y trabajo en estudiantes universitarios de la UIB

El estudio se centra en el conocimiento de los procesos de aprendizaje que se desarrollan en la enseñanza superior, siendo su objetivo principal la evaluación de las estrategias de aprendizaje utilizadas por estudiantes universitarios a lo largo de su formación inicial. Responde a un diseño descriptivo-exploratorio, dirigido a las estrategias de estudio y trabajo de la población universitaria de la Universidad de las Islas Baleares (UIB). Para ello, se procedió a la elaboración de un cuestionario como instrumento de recogida de datos1 sobre estrategias de estudio y trabajo, categorizado en cuatro grupos de estrategias (disposicionales y de apoyo; de búsqueda, recogida y selección de información; de procesamiento y uso de información; metacognitivas, de regulación y control) y sus correspondientes subcategorías. Se trabajó con una muestra de 949 estudiantes de la UIB, clasificados por ámbitos disciplinares y estudios, agrupados en grandes dimensiones (sexo; estudios de ciclo corto y de ciclo largo; rama de estudios; dedicación al estudio y actividad laboral), aportando, para cada una de ellas los datos estadísticos en los que se constata una diferencia significativa.L’estudi està centrat en el coneixement dels processos d’aprenentatge que es desenvolupen a l’ensenyament superior, i el l’objectiu principal és l’avaluació de les estratègies d’aprenentatge utilitzades per estudiants universitaris al llarg de la seva formació inicial. Respon a un disseny descriptiu-exploratori, dirigit a les estratègies d’estudi i treball de la població universitària de la Universitat de les Illes Balears (UIB). En aquest sentit, es va confeccionar un qüestionari com a instrument de recollida de dades sobre estratègies d’estudi i treball, categoritzat en quatre grups d’estratègies (disposicionals i de suport; de cerca, recollida i selecció d’informació; de processament i ús d’informació; metacognitives, de regulació i control) i les subcategories corresponents. Es va treballar amb una mostra de 949 estudiants de la UIB, classificats per àmbits disciplinaris i estudis, agrupats en grans dimensions (sexe; estudis de cicle curt i de cicle llarg; branca d’estudis; dedicació a l’estudi i activitat laboral), que varen aportar, per a cadascuna, dades estadístiques en els quals es constata una diferència significativa.The study is focused on the knowledge of learning processes developed in Higher Education and the main objective is to assess the learning strategies of university students along their initial training. This is a response to a descriptive-exploratory design addressed to the learning and working strategies among the students of the University of the Balearic Islands (UIB). Regarding to this, a question paper was designed as a tool for the collection of data on the studying and working strategies sorted by four strategy groups (dispositional and backup groups; research, collection and selection of information; processing and use of information; metacognitive, regulation and control groups) with their respective subcategories. We took a sample of 949 students from the UIB, sorted by study and disciplinary areas, and we gathered them in larger-dimension groups (gender, shorter and longer degrees, field of study and commitment to studies and work). These groups provided, for each of the samples, statistical information in which an important difference is stated

Intervention test in the macrofossil remains of the sites of the “Hoces de Beteta” (Cuenca, Spain)

Las distintas intervenciones realizadas hasta la fecha en los yacimientos paleontológicos de las “Hoces de Beteta” han permitido recuperar, además de numerosos microfósiles y macrorrestos de invertebrados, diversos restos de vertebrados. Con el objetivo de desarrollar una capacidad de análisis que permita argumentar, en términos precisos, las decisiones tomadas con respecto al proceso restaurador más adecuado para la preparación y conservación de los ejemplares óseos obtenidos, entre éstos, se ha seleccionado, por su representatividad, un fósil procedente del yacimiento de Vadillos-1. El ejemplar elegido, correspondiente a un resto postcraneal de Dinosauria, se encontraba en un estado de preservación relativamente bueno, pero partido en siete fragmentos, presentándose uno de ellos parcialmente recubierto por una concreción carbonatada de elevada consistencia. A este fragmento se le han aplicado ciclos experimentales de limpieza química y mecánica, estableciéndose tratamientos con ácido clorhídrico (HCl) diluido del 15 al 5%, en intervalos de tiempo de 1 a 72h, seguidos de ensayos de eliminación de la matriz mediante aguja percutora. Finalizada la limpieza química y mecánica, se ha procedido a realizar una valoración estimativa de los ciclos desarrollados, mostrándose más eficaces los que incluyen un tratamiento químico más prolongado con ácido más diluido. Por último, los siete fragmentos se han unido mediante un adhesivo concentrado reversible, quedando el resto óseo siglado y depositado en condiciones de preservación adecuadas.The different interventions carried out to date at the palaeontological sites of the “Hoces de Beteta” have allowed to recover, along with numerous microfossils and invertebrate macroremains, diverse vertebrate remains. Aiming to develop the analysis capacity which will allow to argument, in precise terms, the decisions made concerning the most appropriate restoration process for the preparation and preservation of the obtained bone specimens, among these, it has been selected, and due its representativeness, a fossil from the Vadillos-1 site. The chosen specimen corresponds to a postcranial remain of Dinosauria, which was in an adequate preservation state, but fragmented in seven pieces, one of them partially covered by a highly consistent carbonate concretion. Five experimental cycles of chemical and mechanical cleaning have been carried through to this piece, stablishing treatments with hydrogen chloride (HCI) diluted from 15 to 5%, in temporal intervals from 1 to 72h, followed by matrix elimination tests with a hand engraver. Once finished the chemical and mechanical cleaning, an estimative assessment of the developed cycles has been carried out, showing as more efficient those which include a more prolonged chemical treatment with more diluted acid. Finally, the seven fragments have been put together using reversible concentrated adhesive, remaining the specimen labelled and deposited in suitable preservation conditions.Patrimonio Arqueo- lógico y Paleontológico de Castilla-La ManchaDepto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Adsorción de plaguicidas organofosforados por óxido grafítico

A study on the distribution of the mineral nutrients in the different parts of rose bush was carried out with the aim of chossing whichever of these might be most suitable as diagnostic tissue, the cultivar used being "Gabriela". Although for some nutrients (such as N, K) the leaf position on the stem does not seem to have a great effect on its foliar concentrations, in other cases (Ca, Mn, Cu) these concentrations vary widely according to the situation of the leaf. In general, the greatest concentration variations are noted in the youngest leaves, the maximum stability being shown by the first two leaves of 5 leaflets. This stabiliry of the mineral nutrient concentrations in these first two leaves of 5 leaflets makes suitable as samples for diagnostic purposes.Peer reviewe

Internal friction associated with ? martensite in shape memory steels produced by casting route and through additive manufacturing: Influence of thermal cycling on the martensitic transformation.

Among the different families of shape memory alloys (SMA), the Fe-Mn-Si-Cr-Ni alloys have attracted a renewed interest because of its low cost, high corrosion resistance and high recovery strength during the shape memory effect, and the new technologies of additive manufacturing offer unforeseen possibilities for this family of SMA. In the present work, the reversible gamma - epsilon martensitic transformation (MT), responsible for the shape memory effect, is studied in two Fe-Mn-Si-Cr-Ni alloys with high (20.2 wt%) and low (15.8 wt%) Mn content, produced by the conventional route of casting and rolling, in comparison with the MT in another similar alloy, with intermediate Mn content (19.4 wt%), which was produced by gas atomization and additive manufacturing through laser metal deposition. The forward and reverse gamma - epsilon MT is studied by mechanical spectroscopy through the internal friction spectra and the dynamic modulus variation, together with a parallel microstructural characterization including in-situ observation of the gamma - epsilon MT during cooling and heating at the scanning electron microscope. The evolution of the transformed fraction of epsilon martensite, evaluated through the integral area of the internal friction peak, was followed along thermal cycling in all three alloys. Both, the internal friction and the electron microscopy studies show that the epsilon martensite amount increases very fast during the first few cycles, and then decreases with a tendency towards its stabilization for many tens of cycles. The results show that the gamma - epsilon MT is more stable on cycling in the additive manufactured sample than in the conventionally processed samples, opening new avenues for designing shape memory steels to be specifically processed through additive manufacturing

Populismo de extrema derecha y redes sociales: ¿el futuro de la democracia en juego?

Este informe tiene como objetivo brindar una perspectiva amplia sobre la relación entre el populismo y las redes sociales, especialmente en España. Para ello, consideramos el aumento que ha experimentado esta ideología en muchas democracias occidentales y la extensa utilización que los populistas hacen de las redes sociales para transmitir sus mensajes a la población. El informe presenta doce capítulos que abordan la definición del populismo, las características de la comunicación populista, la utilización de las redes sociales por parte de los populistas y las consecuencias de sus estrategias comunicativas en las sociedades democráticas.Este informe forma parte del proyecto “DATAPOP: Polarización, duplicación de audiencias activas y populismo en Twitter. Análisis de la influencia de los discursos populistas en los debates políticos en España (2016-2020)” PGC2018-097352-A-I00 https://www.upf.edu/web/datapo