Chemical, electrochemical and photochemical molecular water oxidation catalysts

Hydrogen release from the splitting of water by simply using sunlight as the only energy source is an old human dream that could finally become a reality. This process involves both the reduction and oxidation of water into hydrogen and oxygen, respectively. While the first process has been fairly overcome, the conversion of water into oxygen has been traditionally the bottleneck process hampering the development of a sustainable hydrogen production based on water splitting. Fortunately, a revolution in this field has occurred during the past decade, since many research groups have been conducting an intense research in this area. Thus, while molecular, well-characterized catalysts able to oxidize water were scarce just five years ago, now a wide range of transition metal based compounds has been reported as active catalysts for this transformation. This review reports the most prominent key advances in the field, covering either examples where the catalysis is triggered chemically, electrochemically or photochemicall

Grup de Recerca Catàlisi d'Oxidació Selectiva (SelOxCat)

La demanda energètica de les societats actuals és cada vegada més elevada, mentre que les reserves de combustibles d'origen no renovable, les més utilitzades, van minvant. En aquesta situació, la recerca de fonts d'energia renovables adquireix una importància rellevant. El grup de recerca SelOxCat (Catàlisid'Oxidació Selectiva) utilitza una àmplia gamma de tècniques per tal d'estudiar, comprendre i desenvolupar les reaccions principals per a la producció de combustibles renovables a partir d'aigua i llum solar.La demanda energética de las sociedades actuales es cada vez más elevada, mientras que las reservas de combustibles de origen no renovable, las más utilizadas, van disminuyendo. En esta situación, la búsqueda de fuentes de energía renovables adquiere una importancia relevante. El grupo de investigación SelOxCat (Catálisis de Oxidación Selectiva) utiliza una amplia gama de técnicas para estudiar, comprender y desarrollar las reacciones principales para la producción de combustibles renovables a partir de agua y luz solar.The energy demand of modern societies is increasingly high, while the reserves of non-renewable fuel sources, the most common, are diminishing. In this situation, the search for renewable energy sources acquires considerable importance. The SelOxCat research group uses a range of techniques to study, understand and develop the reactions leading to the production of renewable fuels from water and sunlight

Light-driven hydrogen evolution assisted by covalent organic frameworks

Altres ajuts: RSCCovalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units, such as triazine rings or diacetylene bridges. The bandgap, charge separation capacity, porosity, wettability, and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks, by extension of conjugation, by adjustment of the size and crystallinity of the pores, and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER), in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed, and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally, the aspects that need to be improved in the coming years will be discussed, such as the degree of dispersibility in water, the global photocatalytic efficiency, and the robustness and stability of the hybrid systems, putting emphasis on both the COF and the metal co-catalyst

Valoració nutricional dels hàbits alimentaris en joves esgrimistes de competició

Introducció i objectius: Si bé les necessitats nutricionals i el perfil somàtic de l'esgrimista d'elit ja estan descrits, aquest no és el cas en joves esgrimistes. L'objectiu d'aquest estudi era doble: descriure el perfil cineantropomètric d'un grup de joves esgrimistes de competició i valorar els seus hàbits alimentaris. Mètodes: Aquest estudi, de caràcter observacional i descriptiu, agrupa les variables analitzades en dues valoracions: a) valoració nutricional (registre de 24 h): energia total, hidrats de carboni, proteïnes, lípids, fibra, colesterol, contingut en aigua de la dieta, vitamines i minerals, i b) valoració cineantropomètrica: talla, pes, somatotip i composició corporal. Resultats: El 26,3% del grup es va situar per sobre dels valors recomanats d'ingesta energètica, mentre que el 57,9% estava per sota. El consum d'hidrats de carboni va ser inferior als valors recomanats, mentre que la ingesta de proteïnes i lípids, superior. El 89,5 i el 63,2% del grup es va situar per sota de les recomanacions de greixos monoinsaturats i poliinsaturats, respectivament. El 89,5% va registrar valors de greixos saturats per sobre de la ingesta recomanada. El consum de fibra va ser, en un 52,6% dels casos, deficitari. El consum de colesterol va ser, en canvi, superior (73,7%). Es van registrar valors de vita-mines que s'ajusten a les recomanacions, però no va ser així pel que fa a alguns minerals. Ambdós sexes configuren grups notablement heterogenis a nivell somàtic. Conclusions: La majoria dels joves esgrimistes analitzats presenten hàbits alimentaris no adequats, ni per mantenir un estat de vida saludable, ni per a la pràctica esportiva. Cal corregir aquests hàbits d'acord amb una educació i un seguiment nutricional correctes. I encara més si el que es pretén és optimitzar el seu rendiment esportiu. La valoració cineantropomètrica ratifica aquests resultats

Valoración nutricional de los hábitos alimentarios en jóvenes esgrimistas de competición

Introducción y objetivos: Si bien las necesidades nutricionales y el perfil somático del esgrimista de élite han sido descritos, no sucede así en jóvenes esgrimistas. El objetivo del presente estudio fue doble: describir el perfil cineantropométrico de un grupo de jóvenes esgrimistas de competición y valorar sus hábitos alimentarios. Métodos: El presente estudio, de carácter observacional y descriptivo, agrupa las variables analizadas en dos valoraciones: a) valoración nutricional (registro de 24 h): energía total, hidratos de carbono, proteínas, lípidos, fibra, colesterol, contenido en agua de la dieta, vitaminas y minerales; b) valoración cineantropométrica: talla, peso, somatotipo y composición corporal. Resultados: El 26,3% del grupo se situó por encima de los valores recomendados de ingesta energética, mientras que el 57,9% lo hizo por debajo. El consumo de hidratos de carbono fue inferior a los valores recomendados, mientras que la ingesta de proteínas y lípidos fue superior. El 89,5 y el 63,2% del grupo se situó por debajo de las recomendaciones de grasas monoinsaturadas y poliinsaturadas, respectivamente. El 89,5% registró valores de grasas saturadas por encima de la ingesta recomendada. El consumo de fibra fue deficitario en el 52,6% de los casos. El consumo de colesterol fue en cambio superior (73,7%). Se registraron valores de vitaminas acordes con las recomendaciones, no siendo así en el caso de algunos minerales. Ambos sexos conforman grupos notablemente heterogéneos a nivel somático. Conclusiones: La mayoría de los jóvenes esgrimistas analizados poseen hábitos alimentarios no adecuados para mantener un estado de vida saludable ni para la práctica deportiva. Resulta necesario corregir dichos hábitos basándose en una correcta educación y seguimiento nutricional. Más aún si lo que se pretende es optimizar su rendimiento deportivo. La valoración cineantropométrica ratifica estos resultados

Organocatalytic vs. Ru-based electrochemical hydrogenation of nitrobenzene in competition with the hydrogen evolution reaction

The electrochemical reduction of organic contaminants allows their removal from water. In this contribution, the electrocatalytic hydrogenation of nitrobenzene is studied using both oxidized carbon fibres and ruthenium nanoparticles supported on unmodified carbon fibres as catalysts. The two systems produce azoxynitrobenzene as the main product, while aniline is only observed in minor quantities. Although PhNO2 hydrogenation is the favoured reaction, the hydrogen evolution reaction (HER) competes in both systems under catalytic conditions. H2 formation occurs in larger amounts when using the Ru nanoparticle based catalyst. While similar reaction outputs were observed for both catalytic systems, DFT calculations revealed some significant differences related to distinct interactions between the catalytic material and the organic substrates or products, which could pave the way for the design of new catalytic materials

Integrating blocking and non-blocking MPI primitives with task-based programming models

In this paper we present the Task-Aware MPI library (TAMPI) that integrates both blocking and non-blocking MPI primitives with task-based programming models. The TAMPI library leverages two new runtime APIs to improve both programmability and performance of hybrid applications. The first API allows to pause and resume the execution of a task depending on external events. This API is used to improve the interoperability between blocking MPI communication primitives and tasks. When an MPI operation executed inside a task blocks, the task running is paused so that the runtime system can schedule a new task on the core that became idle. Once the blocked MPI operation is completed, the paused task is put again on the runtime system’s ready queue, so eventually it will be scheduled again and its execution will be resumed. The second API defers the release of dependencies associated with a task completion until some external events are fulfilled. This API is composed only of two functions, one to bind external events to a running task and another function to notify about the completion of external events previously bound. TAMPI leverages this API to bind non-blocking MPI operations with tasks, deferring the release of their task dependencies until both task execution and all its bound MPI operations are completed. Our experiments reveal that the enhanced features of TAMPI not only simplify the development of hybrid MPI+OpenMP applications that use blocking or non-blocking MPI primitives but they also naturally overlap computation and communication phases, which improves application performance and scalability by removing artificial dependencies across communication tasks.This work has been developed with the support of the European Union H2020 Programme through both the INTERTWinE project (agreement no. 671602) and the Marie Skłodowska-Curie grant (agreement no. 749516); the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Program (SEV-2015-0493); the Spanish Ministry of Science and Innovation (TIN2015-65316-P) and the Generalitat de Catalunya (2017-SGR1414).Peer ReviewedPostprint (author's final draft

Tissue Distribution of Oleocanthal and Its Metabolites after Oral Ingestion in Rats

Claims for the potential health benefits of oleocanthal (OLC), a dietary phenolic compound found in olive oil, are based mainly on in vitro studies. Little is known about the tissue availability of OLC, which is rapidly metabolized after ingestion. In this study, the distribution of OLC and its metabolites in rat plasma and tissues (stomach, intestine, liver, kidney, spleen, lungs, heart, brain, thyroid and skin) at 1, 2 and 4.5 h after the acute intake of a refined olive oil containing 0.3 mg/mL of OLC was examined by LC-ESI-LTQ-Orbitrap-MS. OLC was only detected in the stomach and intestine samples. Moreover, at 2 and 4.5 h, the concentration in the stomach decreased by 36% and 74%, respectively, and in the intestine by 16% and 33%, respectively. Ten OLC metabolites arising from phase I and phase II reactions were identified. The metabolites were widely distributed in rat tissues, and the most important metabolizing organs were the small intestine and liver. The two main circulating metabolites were the conjugates OLC + OH + CH3 and OLC + H2O + glucuronic acid, which may significantly contribute to the beneficial health effects associated with the regular consumption of extra virgin olive oil. However, more studies are necessary to determine the concentrations and molecular structures of OLC metabolites in human plasma and tissues when consumed with the presence of other phenolic compunds present in EVOO. Keywords: LC-ESI-LTQ-Orbitrap; bioaccumulation; extra virgin olive oil; metabolism; polyphenols

Catalitzadors químics, electroquímics i fotoquímics de l'oxidació molecular de l'aigua

L'alliberament d'hidrogen a partir del trencament de l'aigua pel simple ús de la llum solar com a única font d'energia és un vell somni de la humanitat que finalment podria convertir-se en una realitat. Un article del grup de recerca SelOxCat informa dels avenços més destacats en aquest procés, que abasta l'estudi de l'oxidació catalítica de l'aigua mitjançant l'ús de compostos moleculars que contenen ions de metalls de transició, considerant exemples en què la catàlisi s'inicia químicament, electroquímicament i/o fotoquímicament

Surface-Functionalized Nanoparticles as Catalysts for Artificial Photosynthesis

Altres ajuts: acords transformatius de la UABAnalogously to enzymatic catalysis, where the active metal sites and their environment are controlled by protein residues, the catalytic properties of metal nanoparticles (NPs) can be tuned by carefully selecting their surface-coordinated species. In artificial photosynthesis, surface-functionalization emerged in the last decade, grounded on the development of reliable methods for tailored synthesis, advanced characterization and theoretical modeling of metal NPs, altogether with the aim of transferring to the nanoscale the mechanistic knowledge acquired from molecular complexes. Metal NPs surface-functionalization modulates the energetics of key catalytic intermediates, introduces second coordination sphere effects, influences the catalyst-electrolyte interface, and determines the metal NPs surface coverage and, accordingly, the number of accessible active sites. In photoactivated systems, metal NPs surface-functionalization may play a key role in modulating the charge transfers and recombination processes between the light absorber and the active sites and in the light absorber itself. Thus, after a presentation of the most relevant synthetic methods to produce well-defined surface-functionalized metal NPs, a critical analysis of why the above effects are the cornerstone in enhancing their catalytic performance in the key processes of artificial photosynthesis, namely the oxygen evolution reaction, the hydrogen evolution reaction, and the CO2 reduction reaction, is given