Dielectric behaviour of Hf-doped CaCu3Ti4O12 ceramics obtained by conventional synthesis and reactive sintering

CaCu3(Ti4xHfx)O12 ceramics (JC = 0.04, 0.1 and 0.2) were prepared by conventional synthesis (CS) and through reactive sintering (RS), in which synthesis and sintering of the material take place in one single step. The microstructure and the dielectric properties of Hf-doped CCTO (CCTOHf) have been studied by XRD, FE-SEM, AFM, Raman and impedance spectroscopy (IS) in order to correlate the structure, microstructure and the electrical properties. Samples prepared by reactive sintering show slightly higher dielectric constant than those prepared by conventional synthesis in the same way than the pure CCTO. Dielectric constant and dielectric losses decrease slightly increasing Hf content. For CCTOHf ceramics with x> 0.04 for CS and x> 0.1 for RS, a secondary phase HfTi04 appears. As expected, the reactive sintering processing method allows a higher incorporation of Hf in the CCTO lattice than the conventional synthesis one

Dense strontium hexaferrite-based permanent magnet composites assisted by cold sintering process

[EN] The use of rare-earth-based permanent magnets is one of the critical points for the development of the current technology. On the one hand, industry of the rare-earths is highly polluting due to the negative environmental impact of their extraction and, on the other hand, the sector is potentially dependent on China. Therefore, investigation is required both in the development of rare-earth-free permanent magnets and in sintering processes that enable their greener fabrication with attractive magnetic properties at a more competitive price. This work presents the use of a cold sintering process (CSP) followed by a post-annealing at 1100 °C as a new way to sinter composite permanent magnets based on strontium ferrite (SFO). Composites that incorporate a percentage ≤ 10% of an additional magnetic phase have been prepared and the morphological, structural and magnetic properties have been evaluated after each stage of the process. CSP induces a phase transformation of SFO in the composites, which is partially recovered by the post-thermal treatment improving the relative density to 92% and the magnetic response of the final magnets with a coercivity of up to 3.0 kOe. Control of the magnetic properties is possible through the composition and the grain size in the sintered magnets. These attractive results show the potential of the sintering approach as an alternative to develop modern rare-earth-free composite permanent magnets.This work has been supported by the Ministerio Español de Ciencia e Innovación (MICINN), Spain, through the projects MAT2017-86540-C4-1-R and RTI2018-095303-A-C52, and by the European Commission through Project H2020 No. 720853 (Amphibian). C.G.-M. and A.Q. acknowledge financial support from MICINN through the “Juan de la Cierva” program (FJC2018-035532-I) and the “Ramón y Cajal” contract (RYC-2017-23320). S. R.-G. gratefully acknowledges the financial support of the Alexander von Humboldt foundation, Germany. A.S. acknowledges the financialsupport from the Comunidad de Madrid, Spain, for an “Atracción de Talento Investigador” contract (No. 2017-t2/IND5395)

Resolución estructural en 3D de electrocerámicas mediante microscopía Raman confocal

Las propiedades de los materiales cerámicos son una combinación entre las propiedades intrínsecas, definidas por los granos cristalinos, y las propiedades extrínsecas, como son bordes de grano y fases secundarias. La relación entre estos dos elementos produce en muchas ocasiones, la presencia de propiedades inusuales que son la base de muchos materiales electrocerámicos. Sirvan como ejemplo algunos materiales tipo como son: varistores cerámicos, termistores, materiales con coeficiente de resistividad positivo, sensores de borde de grano, etc. En un material electrocerámico con respuesta funcional la correlación entre estructura-microestructura -propiedades es una constante, tanto en la etapa de diseño en laboratorio como en la etapa de producción industrial. El empleo de Microscopía Raman Confocal (MRC) se propone como una metodología relevante para el estudio de los factores que afectan a dichas correlaciones en materiales electrocerámicos. La técnica de MRC constituye una potente herramienta que permite determinar no solo la estructura sino las interacciones entre los elementos microestructurales. La correlación entre estas variables con las propiedades funcionales y la posibilidad de determinar las mismas en condiciones de operación, abren unas posibilidades que hasta la fecha solo estaban en la imaginación de los científicos. En esta presentación se resumen brevemente algunos de los principios relacionados con la técnica de Microscopía Raman Confocal, que junto con ejemplos seleccionados permiten visualizar aspectos relacionados con: la orientación de cristales, identificación fases cristalinas; resolución de nanoestructuras e interfases; determinación y dinámica de dominios ferroeléctricos; presencia de tensiones mecánicas; fenómenos de conducción,... sobre diferentes materiales cerámicos. Los trabajos mostrados son ejemplos de alta resolución en 3D de materiales funcionales como son los materiales electrocerámicos

Challenge 5: Impact of global change on managed ecosystems

Topic Coordinators: María Begoña García ( IPE, CSIC ); Pedro Jordano ( EBD, CSIC )Peer reviewe

COVID-19 Severity and Survival over Time in Patients with Hematologic Malignancies: A Population-Based Registry Study

Mortality rates for COVID-19 have declined over time in the general population, but data in patients with hematologic malignancies are contradictory. We identified independent prognostic factors for COVID-19 severity and survival in unvaccinated patients with hematologic malignancies, compared mortality rates over time and versus non-cancer inpatients, and investigated post COVID-19 condition. Data were analyzed from 1166 consecutive, eligible patients with hematologic malignancies from the population-based HEMATO-MADRID registry, Spain, with COVID-19 prior to vaccination roll-out, stratified into early (February–June 2020; n = 769 (66%)) and later (July 2020–February 2021; n = 397 (34%)) cohorts. Propensity-score matched non-cancer patients were identified from the SEMI-COVID registry. A lower proportion of patients were hospitalized in the later waves (54.2%) compared to the earlier (88.6%), OR 0.15, 95%CI 0.11–0.20. The proportion of hospitalized patients admitted to the ICU was higher in the later cohort (103/215, 47.9%) compared with the early cohort (170/681, 25.0%, 2.77; 2.01–3.82). The reduced 30-day mortality between early and later cohorts of non-cancer inpatients (29.6% vs. 12.6%, OR 0.34; 0.22–0.53) was not paralleled in inpatients with hematologic malignancies (32.3% vs. 34.8%, OR 1.12; 0.81–1.5). Among evaluable patients, 27.3% had post COVID-19 condition. These findings will help inform evidence-based preventive and therapeutic strategies for patients with hematologic malignancies and COVID-19 diagnosis.Depto. de MedicinaFac. de MedicinaTRUEFundación Madrileña de Hematología y HemoterapiaFundación Leucemia y LinfomaAsociación Madrileña de Hematología y Hemoterapiapu

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 17

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 17 de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada, de acceso abierto a todas las áreas del conocimiento, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico. Con esta colección, se aspira contribuir con el cultivo, la comprensión, la recopilación y la apropiación social del conocimiento en cuanto a patrimonio intangible de la humanidad, con el propósito de hacer aportes con la transformación de las relaciones socioculturales que sustentan la construcción social de los saberes y su reconocimiento como bien público

Analysis of tribochemical decomposition of two imidazolium ionic liquids on Ti–6Al–4V through Mechanically Stimulated Gas Emission Spectrometry

Mechanochemical degradation of imidazolium bis(trifluoromethanesulfonyl)imide room-temperature ionic liquids (RTIL) with alkyl and mPEG side groups on Ti¿6Al¿4V substrate was studied through analysis of gas triboemission and Raman spectroscopy. In vacuum the RTIL with longer mPEG chain had better lubricity due to its higher capacity for tribochemical passivation. Raman spectroscopy showed possible bonding of fluorine to the substrate. Mechanical stimulus caused degradation of both anionic and the cationic moieties that further reacted with the substrate and with each other. The relevant decrement of water content during rubbing was found attributable to the proper RTIL and not only to the absorption on the substrate. No volatile sulphur compounds were found supporting the hypothesis of their bonding to Ti substrate.This work was financially supported by the Spanish Ministry of Economy and Competitiveness with the participation of the European Regional Development Fund under the projects RYC-2009-0412, BIA2011-25653 and IPT-2012-1167-120000. The authors acknowledge the contribution of the COST Action CM1207

Versatile approach for the fabrication of functional wrinkled polymer surfaces

A simple and versatile approach to obtaining patterned surfaces via wrinkle formation with variable dimensions and functionality is described. The method consists of the simultaneous heating and irradiation with UV light of a photosensitive monomer solution confined between two substrates with variable spacer thicknesses. Under these conditions, the system is photo-cross-linked, producing a rapid volume contraction while capillary forces attempt to maintain the contact between the monomer mixture and the cover. As a result of these two interacting forces, surface wrinkles were formed. Several parameters play a key role in the formation and final characteristics (amplitude and period) of the wrinkles generated, including the formulation of the photosensitive solution (e.g., the composition of the monomer mixture) and preparation conditions (e.g., temperature employed, irradiation time, and film thickness). Finally, in addition, the possibility of modifying the surface chemical composition of these wrinkled surfaces was investigated. For this purpose, either hydrophilic or hydrophobic comonomers were included in the photosensitive mixture. The resulting surface chemical composition could be finely tuned as was demonstrated by significant variations in the wettability of the structured surfaces, between 56° and 104°, when hydrophilic and hydrophobic monomers were incorporated, respectivelyPeer Reviewe

Chemical and Topographical Modification of Polycarbonate Surfaces through Diffusion/Photocuring Processes of Hydrogel Precursors Based on Vinylpyrrolidone

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.langmuir. 6b04143. Raman spectra of the PC used as a substrate for the hydrogel formation, a pure hydrogel constructed from VP, and the modified surface resulting upon photopolymerization and hydrogel detachment. Raman confocal spectra of a PC surface treated with a photopolymerizable monomer mixture. Hydrogel swelling as a function of the solvent used and the amount of crosslinking agent used. Optical image and 3D image of a pristine PC surface together with roughness measurement (PDF)Facile procedures capable of simultaneously conferring hydrophilicity and tailored topography to surfaces of hydrophobic supports, such as polycarbonate (PC), are very attractive but rare. In this work, we describe a simple methodology to wrinkle PC surfaces after a process of (a) contacting with a photopolymerizable vinylic solution, (b) UV curing of such solutions, and (c) detachment of the formed polymer network, upon swelling in ethanol. The influence of different parameters such as contact lag time between the PC surface and the polymerizable solution, the monomer concentration and type of solvents, as well as the cross-linking degree on the formation of wrinkles, has been studied. The dimensions of the wrinkles can be tailored to some extent by altering the different parameters. Surface chemistry has been analyzed by contact angle measurements and by confocal Raman microscopy. The results are consistent with a chemical alteration of the surface and the formation of an outer hydrogel layer, which is interpenetrated into the PC structure. A mechanism of monomer diffusion and PC swelling that produces surface instabilities and wrinkling is proposed.The authors gratefully acknowledge support from the Consejo Superior de Investigaciones Cientifí cas (CSIC). Equally, this work was financially supported by the Ministerio de Economía y Competitividad (MINECO) through MAT2013-47902-C2-1- R, MAT2013-42957-R, and MAT2016-78437-R.Peer Reviewe

Tribochemical Decomposition of Light Ionic Hydrides at Room Temperature

Tribochemical decomposition of magnesium hydride (MgH2) induced by deformation at room temperature was studied on a micrometric scale, in situ and in real time. During deformation, a near-full depletion of hydrogen in the micrometric affected zone is observed through an instantaneous (t < 1 s) and huge release of hydrogen (3–50 nmol/s). H release is related to a nonthermal decomposition process. After deformation, the remaining hydride is thermally decomposed at room temperature, exhibiting a much slower rate than during deformation. Confocal-microRaman spectroscopy of the mechanically affected zone was used to characterize the decomposition products. Decomposition was enhanced through the formation of the distorted structure of MgH2 with reduced crystal size by mechanical deformation.We acknowledge financial support from the Ministry of Economy and Competitiveness of Spain through the grants RYC-2009-0412, BIA-2011-25653, and IPT-2012-1167-120000 with participation of the European Regional Development Fund (FEDER) as well as MINECO 2011-22780 and MAT2013-48009-C4-1-P