Encontrado(s) 2198529 resultado(s)
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Single Electron Transfer Steps in Water Oxidation Catalysis. Redefining the Mechanistic Scenario

  • Funes-Ardoiz, Ignacio
  • Garrido-Barros, Pablo
  • Llobet, Antoni
  • Maseras, Feliu
The systematic computational study of the mechanism for water oxidation in four different complexes confirms the existence of an alternative mechanism to those previously reported: the single electron transfer - water nucleophilic attack (SET-WNA). The new mechanism relies on two SET steps, and features the existence of an intermediate with a (HO•••OH)-moiety attached to the metal center. It is operative in at least three representative copper based complexes, and is the only option that explains the experimentally observed efficiency in two of them. The proposal of this new reaction pathway redefines the mechanistic scenario and importantly, generates a completely new avenue for designing more efficient water oxidation catalysts based on first row transition metals.

Photoelectrochemical Behavior of a Molecular Ru-Based Water-Oxi- dation Catalyst Bound to TiO2-Protected Si Photoanodes

  • Matheu, Roc
  • Moreno-Hernández, Ivan A
  • Sala, Xavier
  • Gray, Harry B
  • Brunschwig, Bruce S
  • Llobet, Antoni
  • Lewis, Nathan S
A hybrid photoanode based on a molecular water oxidation precatalyst was prepared from TiO2-protected n- or p+-Si coated with multiwalled carbon nanotubes (CNT) and the ruthenium-based water oxidation precatalyst [RuIV(tda)(py-pyr)2(O)], 1(O) (tda2– is [2,2′:6′,2″-terpyridine]-6,6″-dicarboxylato and py-pir is 4-(pyren-1-yl)-N-(pyridin-4-ylmethyl)butanamide). The Ru complex was immobilized by π–π stacking onto CNTs that had been deposited by drop casting onto Si electrodes coated with 60 nm of amorphous TiO2 and 20 nm of a layer of sputtered C. At pH = 7 with 3 Sun illumination, the n-Si/TiO2/C/CNT/[1+1(O)] electrodes exhibited current densities of 1 mA cm–2 at 1.07 V vs NHE. The current density was maintained for >200 min at a constant potential while intermittently collecting voltammograms that indicated that over half of the Ru was still in molecular form after O2 evolution.

The Role of Seven Coordination in Ru-catalyzed Water Oxidation

  • Matheu, Roc
  • Ertem, Mehmed Z
  • Pipelier, Muriel
  • Lebreton, Jacques
  • Dubreuil, Didier
  • Benet-Buchholz, Jordi
  • Sala, Xavier
  • Tessier, Arnaud
  • Llobet, Antoni
A family of Ru complexes based on the pentadentate t5a3- ligand ((2,5-bis(6-carboxylatopyridin-2- yl)pyrrol-1-ide) and pyridine (py) that include, {RuII(Ht5a--N2O)(py)3}, 1HII(-N2O), {RuIII(t5a-- N3O1.5)(py)2}, 2III(-N3O1.5) and {RuIV(t5a--N3O2)(py)2}+, {2IV(-N3O2)}+ has been prepared and thoroughly characterized. Complexes 1HII(-N2O), 2III(-N3O1.5) and {2IV(-N3O2)}+ have been investigated in solution by spectroscopic methods (NMR, UV-vis) and in the solid state by single- crystal X-ray diffraction analysis and complemented by density functional theory (DFT) calculations. The redox properties of complex 2III(-N3O1.5) have been studied by electrochemical methods (CV and DPV), showing its easy access to high oxidation states, thanks to the trianionic nature of the t5a3- ligand. In neutral to basic conditions complex {2IV(-N3O2)}+ undergoes aquation generating {RuIV(OH)(t5a--N2O)(py)2}, 2IV(OH)(-N2O). Further oxidation of the complex forms {RuV(O)(t5a--N2O)(py)2}, 2V(O)(-N2O) that is a very efficient water oxidation catalyst, reaching TOFMAX of 9400 s-1 at pH = 7.0, as measured via foot of the wave analysis. The key to fast kinetics for the catalytic oxidation of water to dioxygen by 2V(O)(-N2O) is due to not only the easy access to high oxidation states but also to the intramolecular hydrogen bonding provided by the non- coordinated dangling carboxylate at the transition state, as corroborated by DFT calculations.

Ni-Catalyzed Site-Selective Dicarboxylation of 1,3-Dienes with CO2

  • Tortajada, Andreu
  • Ryo, Ninokata
  • Martín, Rubén
A site-selective catalytic incorporation of multiple CO2 molecules into 1,3-dienes en route to adipic acids is described. This protocol is characterized by its mild conditions, excellent chemo- and regioselectivity and ease of execution under CO2 (1 atm), including the use of bulk butadiene and/or isoprene feedstocks.

Desarrollo, seguimiento y evaluación de la formación especializada en el modelo troncal.

  • Carbajo, Pilar
  • Castrodeza, Javier
  • Gual Sala, Arcadi
  • López Blanco, Juan A.
  • Martín Zurro, Amando
  • Sánchez Biezma, Esperanza
La implantación de la troncalidad en la formación sanitaria especializada en España es el cambio más profundo y complejo que se introduce en la regulación del sistema de formación especializada desde el año 1978. Este hecho hace imprescindible la puesta en marcha de un conjunto de elementos estructurales, organizativos y de acción dirigidos específicamente a garantizar que el proceso se implante siguiendo las premisas y calendarios previstos en las disposiciones legales que le dan soporte y de acuerdo con conceptos y evidencias científicamente fundados y que traduzcan también la experiencia acumulada en España y otros países en relación con estos temas.

El 'Real Decreto de Troncalidad' de la formación especializada

  • Gual Sala, Arcadi
  • Martín Zurro, Amando
  • Rodriguez de Castro, Felipe
Una vez la troncalidad ha dejado de ser un proyecto para convertirse en un RD tangible en el papel del BOE, la Fundación Educación Médica (FEM)considera oportuno y pertinente reflexionar sobre qué es la troncalidad, para qué es necesaria aquí y ahora, y cómo debería ser el proceso de su desarrollo.

Del seny polític dels catalans: una visió crítica del segle XX

  • Cuscó i Clarasó, Joan, 1971-
Vist el que passa en el món en què vivim (també a Catalunya i a l'Estat Espanyol) el títol que hem escollit sembla un oxímoron. Hi ha polítics amb seny? Què vol dir tenir seny? Perquè als catalans se'ns diu i rediu que som gent de seny? Aquestes són preguntes importants. I les intentarem descabdellar a partir d'autors i de fets concrets. I centrant-nos en el període del segle xx.

Blood pressure values and depression in hypertensive individuals at high cardiovascular risk

  • Mejía-Lancheros, Cília
  • Estruch Riba, Ramon
  • Martínez-González, Miguel Ángel, 1957-
  • Salas Salvadó, Jordi
  • Corella Piquer, Dolores
  • Gómez Gracia, Enrique
  • Fiol Sala, Miguel
  • Santos, José Manuel
  • Fitó Colomer, Montserrat
  • Arós, Fernando
  • Serra Majem, Lluís
  • Pintó Sala, Xavier
  • Basora, Josep
  • Sorlí, José V.
  • Muñoz, Miguel Ángel
BACKGROUND: Hypertension and depression are both important risk factors for cardiovascular diseases. Nevertheless, the association of blood pressure on and depression has not been completely established. This study aims to analyze whether depression may influence the control of blood pressure in hypertensive individuals at high cardiovascular risk. METHODS: Cross-sectional study, embedded within the PREDIMED clinical trial, of 5954 hypertensive patients with high cardiovascular risk factor profiles. The relationship between blood pressure control and depression was analyzed. A multivariate analysis (logistic and log-linear regression), adjusting for potential confounders (socio-demographic factors, body mass index, lifestyle, diabetes, dyslipidemia, and antihypertensive treatment), was performed. RESULTS: Depressive patients, with and without antidepressant treatment, had better blood pressure control (OR: 1.28, CI 95%: 1.06-1.55, and OR: 1.30, CI 95%: 1.03-1.65, respectively) than non-depressive ones. Regarding blood pressure levels, systolic blood pressure values (mmHg) were found to be lower in both treated and untreated depressive patients (Log coefficient Beta: -1.59, 95% CI: -0.50 to -2.69 and Log coefficient Beta: -3.49, 95% CI: -2.10 to -4.87, respectively). CONCLUSIONS: Among hypertensive patients at high cardiovascular risk, the control of blood pressure was better in those diagnosed with depression. TRIAL REGISTRATION: Unique identifier: ISRCTN35739639.

Mediterranean diet and cardiodiabesity: a review

  • García Fernández, Elena
  • Rico Cabanas, Laura
  • Rosgaard, Nanna
  • Estruch Riba, Ramon
  • Bach Faig, Anna
Cardiodiabesity has been used to define and describe the well-known relationship between type 2 Diabetes Mellitus (T2DM), obesity, the metabolic syndrome (MetS) and cardiovascular disease (CVD). The objective of this study was to perform a scientific literature review with a systematic search to examine all the cardiovascular risk factors combined and their relationship with adherence to the Mediterranean Diet (MedDiet) pattern as primary prevention against cardiodiabesity in a holistic approach. Research was conducted using the PubMed database including clinical trials, cross-sectional and prospective cohort studies. Thirty-seven studies were reviewed: fourteen related to obesity, ten to CVD, nine to MetS, and four to T2DM. Indeed 33 provided strong evidence on the association between adherence to a MedDiet and a reduced incidence of collective cardiodiabesity risk in epidemiological studies. This scientific evidence makes the MedDiet pattern very useful for preventive strategies directed at the general population and also highlights the need to consider all these diet-related risk factors and health outcomes together in daily primary care.

Cromogranina A en adenomas hipofisarios humanos

  • Vidal, Noemí
  • Paules, Mª José
  • Villabona Artero, Carlos
  • Gómez, José Manuel
  • Ferrer, Isidro (Ferrer Abizanda)
Introducción: Las cromograninas son proteínas extensamente distribuidas en el sistema neuroendocrino, y su expresión puede usarse en la caracterización de los tumores neuroendocrinos. Material y métodos: Este estudio analiza mediante inmunohistoquímica la presencia de cromogranina A en 32 biopsias de adenomas hipofisarios humanos, secretores y no secretores. Resultados: Todos los adenomas secretores de FSH y los no secretores muestran inmunoreactividad intensa para cromogranina A, mientras que otros adenomas hipofisarios son negativos o débilmente positivos en escasas células. Conclusiones: La cromogranina A puede utilizarse como marcador de adenomas hipofisarios humanos no secretores.

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