Suchergebnisse

The objective of this article is to analyze the relationship between Túquerres and Latacunga from the action and theory deployed by Simón Rodríguez in both places during the construction of the Republic. Throughout the text, the importance assigned by Simón Rodríguez to the conformation of the Republic is shown; the main components of republican education and its implementation methodology are analyzed, and finally, the relations of this vast region regarding the education system required today are addressed. Few educational projects have emphasized the profound link between education and democratic and social life as much as that of Simón Rodríguez; hence, understanding this model requires a prior examination of his conception of American society, which, in his opinion, was marked not only by acute national conflicts but, above all, by those of a social nature and therefore, divided by a new genre of dominators and dominated people. On these and other categories, Simón Rodríguez organizes his plan of a 'republican and social education', as he himself calls it, of which he had been speaking and writing publicly and privately for more than twenty-four years, based on a strong criticism and rupture with traditional or testamentary education and bringing at the same time a clear alternative character to the project. It is in the denunciation of an inherited and current past, as well as in the announcement of a future to be built, that he constitutes the plan of a 'republican and social education', making both phases of the project converging into two sides of the same coin. ; El objetivo de este artículo es analizar la relación entre Túquerres y Latacunga a partir de la acción y la teoría desplegada por Simón Rodríguez en uno y otro lugar durante la construcción de la República. A lo largo del texto se muestra la importancia asignada por Simón Rodríguez a la conformación de la República; se analizan los principales componentes de la educación republicana y su metodología de implementación, y finalmente, se aborda las relaciones de esta vasta región respecto del sistema de educación que se requiere en la actualidad. Pocos proyectos educativos han resaltado tanto la profunda vinculación de la educación con la vida democrática y social como el de Simón Rodríguez; de ahí que comprender este modelo suponga examinar previamente su concepción de la sociedad americana, la misma que, a su criterio se presentaba marcada no solo por agudos conflictos nacionales sino ante todo por los de carácter social y por eso dividida por un nuevo género de dominadores y dominados. Sobre estas y otras categorías organiza Simón Rodríguez su plan de una 'educación republicana y social', como él mismo la denomina, y sobre la cual nos narra que hacía ya más de veinticuatro años que él venía hablando y escribiendo pública y privadamente, apoyándose en una fuerte crítica y ruptura con la educación tradicional o testamentaria e imprimiendo a su vez al proyecto un claro carácter alternativo. Es en la denuncia de un pasado heredado y vigente, así como en el anuncio de un porvenir por construir, como constituye el plan de una 'educación republicana y social', haciendo que una y otra fase del proyecto confluyesen como las dos caras de una misma moneda. ; O objetivo deste artigo é analisar a relação entre Túquerres e Latacunga a partir da ação e da teoria implantada por Simón Rodríguez em um e outro lugar durante a construção da República. Ao longo do texto é evidenciada a importância atribuída por Simón Rodríguez à formação da República; São analisados os principais componentes da educação republicana e sua metodologia de implementação e, por fim, abordam-se as relações dessa vasta região com o sistema educacional que se exige atualmente. Poucos projetos educacionais destacaram tanto o vínculo profundo entre a educação e a vida democrática e social quanto o de Simón Rodríguez; Portanto, compreender esse modelo significa examinar previamente sua concepção de sociedade americana, que, em sua opinião, foi marcada não apenas por agudos conflitos nacionais, mas sobretudo por aqueles de natureza social e, portanto, dividida por um novo gênero de dominadores e dominados. Sobre essas e outras categorias, Simón Rodríguez organiza seu plano de uma 'educação republicana e social', como ele mesmo a chama, sobre a qual nos conta que fazia quase vinte e quatro anos que falava e escrevia em público e em particular. com uma crítica forte e rompimento com a educação tradicional ou testamentária e por sua vez dando ao projeto um caráter alternativo claro. É na denúncia de um passado herdado e atual, bem como no anúncio de um futuro a ser construído, que se constitui o projeto de uma 'educação republicana e social', fazendo convergir as duas fases do projeto como as duas faces do uma mesma moeda.

11 páginas, 3 figuras.-- PACS number8s): 05.10.Gg, 64.60.Ht, 68.35.Ct, 68.35.Rh ; In order to perform numerical simulations of the Kardar-Parisi-Zhang (KPZ) equation, in any dimensionality, a spatial discretization scheme must be prescribed. The known fact that the KPZ equation can be obtained as a result of a Hopf-Cole transformation applied to a diffusion equation (with multiplicative noise) is shown here to strongly restrict the arbitrariness in the choice of spatial discretization schemes. On one hand, the discretization prescriptions for the Laplacian and the nonlinear (KPZ) term cannot be independently chosen. On the other hand, since the discretization is an operation performed on space and the Hopf-Cole transformation is local both in space and time, the former should be the same regardless of the field to which it is applied. It is shown that whereas some discretization schemes pass both consistency tests, known examples in the literature do not. The requirement of consistency for the discretization of Lyapunov functionals is argued to be a natural and safe starting point in choosing spatial discretization schemes. We also analyze the relation between real-space and pseudospectral discrete representations. In addition we discuss the relevance of the Galilean-invariance violation in these consistent discretization schemes and the alleged conflict of standard discretization with the fluctuation-dissipation theorem, peculiar of one dimension. ; Financial support from the Spanish Government Project No. CGL2007-64387/CLI from MEC (H.S.W. and J.A.R.), and Projects No. MTM2008-03754 (C.E.) and No. FIS2006-12253-C06-04 (M.S.d.L.L.) from MICINN. R.R.D. acknowledges financial support from CONICET and UNMdP of Argentina. The international collaboration has been facilitated by AECID, Spain through Projects No. A/013666/07 and No. A/018685/08. ; Peer reviewed

Compositional engineering of BiFeO3 can significantly boost its photovoltaic performance. Therefore, controlling site substitution and understanding how it affects the optical and electronic properties while achieving robust and stable phases is essential to continue progressing in this field. Here the influence of cation co-substitution in BiFeO3 on phase purity, optical and electronic properties is investigated by means of X-ray diffraction, spectroscopic ellipsometry and X-ray absorption spectroscopy, respectively. Piezoelectric force microscopy and ferroelectric characterization at room temperature has been carried out in co-doped BiFeO3 films. First-principles calculations are also performed and compared to the experimental observations. It is shown that the incorporation of La3+ in Bi(Fe,Co)O3 films improves phase purity and stability while preserving the reduced band gap achieved in metastable Bi(Fe,Co)O3. Moreover, it is suggested that the changes in the optoelectronic properties are mainly dictated by the hybridisation between unoccupied Co 3d and O 2p states along with the presence of Co3+/Co2+ species. This thorough study on (Bi,La)(Fe,Co)O3 thin films coupled with the use of a cost-effective and facile solution deposition synthesis increases the motivation to continue exploiting the potential of these perovskite materials. ; This research was supported by the Spanish Ministerio de Ciencia, Innovación y Universidades ("Severo Ochoa" Programme for Centres of Excellence in R&D CEX2019-000917-S, MAT2017-83169-R, RTI2018-093996-B-C32, PID2019-107727RB-I00 (AEI/FEDER, EU)). P. M. thanks financial support from FPI fellowship (PRE2018-084618). C. M. and C. C. acknowledge computational resources and technical assistance from the Australian Government and the Government of Western Australia through the National Computational Infrastructure (NCI) and Magnus under the National Computational Merit Allocation Scheme and The Pawsey Supercomputing Centre. The authors acknowledge Prof. J. Fontcuberta for providing access to his experimental facilities and the support of ALBA staff for the successful performance of the measurements at CIRCE beamline of the ALBA Synchrotron Light Source. I. F. and C. C. acknowledge support from the Spanish Ministry of Science, Innovation and Universities under the "Ramón y Cajal" fellowship RYC2017-226531 and RYC2018-024947-I, respectively. M. C and I. F acknowledge Beca Leonardo from fundación BBVA. H. T is financially supported by China Scholarship Council (CSC) with no. 201906050014. The work of P. M. and H. T have been done in the framework of the doctorate in Materials Science of the Autonomous University of Barcelona. ; Peer reviewed

This study addresses the yet unresolved CO2 methanation mechanism on a Ru/CeO2 catalyst by means of near-ambient-pressure X-ray photoelectron spectroscopy (NAP–XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) complemented with periodic density functional theory (DFT) calculations. NAP–XPS results show that the switch from H2 to CO2 + H2 mixture oxidizes both the Ru and CeO2 phases at low temperatures, which is explained by the CO2 adsorption modes assessed by means of DFT on each representative surface. CO2 adsorption on Ru is dissociative and moderately endergonic, leading to polybonded Ru-carbonyl groups whose hydrogenation is the rate-determining step in the overall process. Unlike on Ru metal, CO2 can be strongly adsorbed as carbonates on ceria surface oxygen sites or on the reduced ceria at oxygen vacancies as carboxylates (CO2–δ), resulting in the reoxidation of ceria. Carboxylates can then evolve as CO, which is released either via direct splitting at relatively low temperatures or through stable formate species at higher temperatures. DRIFTS confirm the great stability of formates, whose depletion relates with CO2 conversion in the reaction cell, while carbonates remain on the surface up to higher temperatures. CO generation on ceria serves as an additional reservoir of Ru-carbonyls, cooperating to the overall CO2 methanation process. Altogether, this study highlights the noninnocent role of the ceria support in the performance of Ru/CeO2 toward CO2 methanation. ; The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Science and Innovation (PID2019-105960RB-C22), Generalitat Valenciana (Project PROMETEO/2018/076), and the EU (FEDER funding). A.D.-Q. and M.G.-M. acknowledge the financial support from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 713567 and Science Foundation Ireland Research Centre award 12/RC/2278_P2. F.C.H. acknowledges the Argentinian National Research Council (CONICET) for the financial support. C.E. acknowledges funding from the MICINN/FEDER RTI2018-093996-B-32 project. The computational results of this research have been achieved using the DECI resource Salomon based in the Czech Republic at the IT4Innovations National Supercomputing Center with support from the PRACE aisbl. The DJEI/DES/SFI/HEA Irish Centre for High-End Computing (ICHEC) is also acknowledged for the provision of computational facilities.

[EN] Sunlight plays a critical role in the development of emerging sustainable energy conversion and storage technologies. Light-induced CO2 reduction by artificial photosynthesis is one of the cornerstones to produce renewable fuels and environmentally friendly chemicals. Interface interactions between plasmonic metal nanoparticles and semiconductors exhibit improved photoactivities under a wide range of the solar spectrum. However, the photoinduced charge transfer processes and their influence on photocatalysis with these materials are still under debate, mainly due to the complexity of the involved routes occurring at different timescales. Here, we use a combination of advanced in situ and time-resolved spectroscopies covering different timescales, combined with theoretical calculations, to unravel the overall mechanism of photocatalytic CO2 reduction by Ag/TiO2 catalysts. Our findings provide evidence of the key factors determining the enhancement of photoactivity under ultraviolet and visible irradiation, which have important implications for the design of solar energy conversion materials. ; This work has received funding from the European Research Council (ERC), within the projects Intersolar (291482) and HyMAP programme (648319) under the European Union's Horizon 2020 research and innovation programme. The results reflect only the authors' view and the Agency is not responsible for any use that may be made of the information they contain. V.A.P.O. thanks funding from the Spanish Ministry of Economy and Competitiveness (project ENE2016-79608-C2-1-R). A.R. acknowledges the European Commission Marie Curie CIG. M.B. acknowledges the Juan de la Cierva Formación program: FJCI-2016-30567, V.A.P.O. acknowledges support from the Centre of Supercomputacio de Catalunya (CESCA) and to ALBA Cells Synchrotron facilities. Authors thank Dr. Xiaoe Li for assistance in TiO2 films preparation. Support from the Repsol Technology Centre in gratefully acknowledged. ; Peer reviewed

[EN] Ruthenium nanoparticles with a core-shell structure formed by a core of metallic ruthenium and a shell of ruthenium carbide have been synthesized by a mild and easy hydrothermal treatment. The dual structure and composition of the nanoparticles have been determined by synchrotron X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) analysis, and transmission electron microscopy (TEM) imaging. According to depth profile synchrotron XPS and X-ray diffraction (XRD) analysis, metallic ruthenium species predominate in the inner layers of the material, ruthenium carbide species being located on the upper surface layers. The ruthenium carbon catalysts presented herein are able to activate both CO2 and H-2, exhibiting exceptional high activity for CO2 hydrogenation at low temperatures (160-200 degrees C) with 100% selectivity to methane, surpassing by far the most active Ru catalysts reported up to now. On the basis of catalytic studies and isotopic (CO)-C-13/(CO2)-C-12/H-2 experiments, the active sites responsible for this unprecedented activity can be associated with surface ruthenium carbide (RuC) species, which enable CO2 activation and transformation to methane via a direct CO2 hydrogenation mechanism. Both the high activity and the absence of CO in the gas effluent confer relevance to these catalysts for the Sabatier reaction, a chemical process with renewed interest for storing surplus renewable energy in the form of methane. ; The research leading to these results has received funding from the Spanish Ministry of Science, Innovation and Universities through "Severo Ochoa" Excellence Programme (SEV-2016-0683) and the PGC2018-097277-B-100 (MCIU/AEI/FEDER, UE) project. The authors also thank the Microscopy Service of UPV for kind help with measurements. A G.O. thanks "Severo Ochoa" Programme (SEV-2016-0683) for a predoctoral fellowship. C.-H.C. acknowledges financial support from MOST project 107-2112-M-032-005. J.C. thanks the Spanish Government (MINECO) for a "Severo ...

21 pags., 5 figs. ; Subnanometer-sized metal clusters often feature a molecule-like electronic structure, which makes their physical and chemical properties significantly different from those of nanoparticles and bulk material. Considering potential applications, there is a major concern about their thermal stability and susceptibility towards oxidation. Cu clusters of only 5 atoms (Cu5 clusters) are first synthesized in high concentration using a new-generation wet chemical method. Next, it is shown that, contrary to what is currently assumed, Cu5 clusters display nobility, beyond resistance to irreversible oxidation, at a broad range of temperatures and oxygen pressures. The outstanding nobility arises from an unusual reversible oxidation which is observed by in situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy on Cu5 clusters deposited onto highly oriented pyrolitic graphite at different oxygen pressures and up to 773 K. This atypical property is explained by a theoretical approach combining different state-of-the-art first principles theories. It reveals the essential role of collective quantum effects in the physical mechanism responsible for the nobility of Cu5 clusters, encompassing a structural 'breathing' through concerted Cu–Cu elongations/contractions upon O2 uptake/release, and collective charge transfer as well. A predictive phase diagram of their reversible oxidation states is also delivered, agreeing with the experimental observations. The collective quantum effects responsible of the observed nobility are expected to be general in subanometer-sized metal clusters, pushing this new generation of materials to an upper level. ; This work has been partly supported by the European Union's Horizon 2020 Research and Innovation Programme un-der Grant Agreement No. 825999; the Spanish Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, UE) under Grant No. MAT2016-75354-P; the Austrian Science Fund (FWF) under Grant P29893-N36; the CMST COST Action CM1405 "Molecules in Motion" (MOLIM); the Xunta de Galicia, Spain (Grupos Ref. Comp.ED431C 2017/22 and AEMAT ED431E 2018/08); Obra Social Fundación La Caixa: Ref.LCF/PR/PR12/11070003; ANPCyT PICT (2017-1220 and 2017-3944) and UNLP (Project11/X790), Argentina. ; No