Carbon monoxide adsorption on platinum-osmium and platinum-ruthenium-osmium mixed nanoparticles

Density functional calculations (DFT) on carbon monoxide (CO) adsorbed on platinum, platinum-osmium, and platinum-ruthenium-osmium nanoclusters are used to elucidate changes on the adsorbate internal bond and the carbon-metal bond, as platinum is alloyed with osmium and ruthenium atoms. The relative strengths of the adsorbate internal bond and the carbon-metal bond upon alloying, which are related to the DFT calculated C–O and C–Pt stretching frequencies, respectively, cannot be explained by the traditional 5σ-donation/2π*-back-donation theoretical model. Using a modified π-attraction σ-repulsion mechanism, we ascribe the strength of the CO adsorbate internal bond to changes in the polarization of the adsorbate-substrate hybrid orbitals towards carbon. The strength of the carbon-metal bond is quantitatively related to the CO contribution to the adsorbate-substrate hybrid orbitals and the sp and d populations of adsorbing platinum atom. This work complements prior work on corresponding slabs using periodic DFT. Similarities and differences between cluster and periodic DFT calculations are discussed

Novel Energy Sources -Material Architecture and Charge Transport in Solid State Ionic Materials for Rechargeable Li ion Batteries

Since its introduction in the consumer market at the beginning of 1990s by Sony Corporation ‘Li-ion rechargeable battery’ and ‘LiCoO2 cathode’ is an inseparable couple for highly reliable practical applications. However, a separation is inevitable as Li-ion rechargeable battery industry demand more and more from this well serving cathode. Spinel-type lithium manganate (e.g., LiMn2O4), lithium-based layered oxide materials (e.g., LiNiO2) and lithium-based olivine-type compounds (e.g., LiFePO4) are nowadays being extensively studied for application as alternate cathode materials in Li-ion rechargeable batteries. Primary goal of this project was the advancement of Li-ion rechargeable battery to meet the future demands of the energy sector. Major part of the research emphasized on the investigation of electrodes and solid electrolyte materials for improving the charge transport properties in Li-ion rechargeable batteries. Theoretical computational methods were used to select electrodes and electrolyte material with enhanced structural and physical properties. The effect of nano-particles on enhancing the battery performance was also examined. Satisfactory progress has been made in the bulk form and our efforts on realizing micro-battery based on thin films is close to give dividend and work is progressing well in this direction

Mobilization of xanthine oxidase from the gastrointestinal tract in acute pancreatitis

BACKGROUND: Xanthine oxidoreductase has been proposed to play a role in the development of local and systemic effects of acute pancreatitis. Under physiologic conditions, the enzyme exists mainly as xanthine dehydrogenase (XDH) but can be converted by proteolytic cleavage to its superoxide-generating form xanthine oxidase (XOD). In addition to its intracellular location XDH/XOD is also associated to the polysaccharide chains of proteoglycans on the external endothelial cell membrane. In the early stages of acute pancreatitis, this enzyme seems to be arising from its mobilization from the gastrointestinal endothelial cell surface. Taking into account the ability of α-amylase to hydrolyze the internal α-1,4 linkages of polysaccharides, we wanted to elucidate the involvement of α-amylase in XDH/XOD mobilization from the gastrointestinal endothelial cell surface and the relevance of the ascitic fluid (AF) as the source of α-amylase in experimental acute pancreatitis. METHODS: Acute pancreatitis was induced in male Wistar rats by intraductal administration of 5% sodium taurocholate. In another experimental group 3000 U/Kg α-amylase was i.v. administered. The concentrations of XDH, XOD and α-amylase in plasma and AF and myeloperoxidase (MPO) in lung have been evaluated. In additional experiments, the effect of peritoneal lavage and the absorption of α-amylase present in the AF by an isolated intestine have been determined. RESULTS: Similar increase in XDH+XOD activity in plasma was observed after induction of acute pancreatitis and after i.v. administration of α-amylase. Nevertheless, the conversion from XDH to XOD was only observed in the pancreatitis group. Lung inflammation measured as MPO activity was observed only in the pancreatitis group. In addition peritoneal lavage prevented the increase in α-amylase and XDH+XOD in plasma after induction of pancreatitis. Finally, it was observed that α-amylase is absorbed from the AF by the intestine. CONCLUSIONS: During the early stages of acute pancreatitis, α-amylase absorbed from AF through the gastrointestinal tract could interfere with the binding of XDH/XOD attached to glycoproteins of the endothelial cells. Proteolytic enzymes convert XDH into its oxidase form promoting an increase in circulating XOD that has been reported to be one of the mechanisms involved in the triggering of the systemic inflammatory process

Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based "Quasi-Artificial Leaf"

[EN] Hydrogen generation by using quantum dot (QD) based heterostructures has emerged as a promising strategy to develop artificial photosynthesis devices. In the present study, we sensitize mesoporous TiO2 electrodes with in-situ-deposited PbS/CdS QDs, aiming at harvesting light in both the visible and the near-infrared for hydrogen generation. This heterostructure exhibits a remarkable photocurrent of 6 mA.cm(-2), leading to 60 mL.cm(-2).day(-1) hydrogen generation. Most importantly, confirmation of the contribution of infrared photons to H-2 generation was provided by the incident-photon-to-current-efficiency (IPCE), and the integrated current was in excellent agreement with that obtained through cyclic voltammetry. The main electronic processes (accumulation, transport, and recombination) were identified by impedance spectroscopy, which appears as a simple and reliable methodology to evaluate the limiting factors of these photoelectrodes. On the basis of this TiO2/PbS/CdS heterostructrure, a "quasi-artificial leaf' has been developed, which has proven to produce hydrogen under simulated solar illumination at (4.30 +/- 0.25) mL.cm(-2).day(-1).We acknowledge support by projects from Ministerio de Economia y Competitividad (MINECO) of Spain (Consolider HOPE CSD2007-00007, MAT2010-19827), Generalitat Valenciana (PROMETEO/2009/058 and Project ISIC/2012/008 "Institute of Nanotechnologies for Clean Energies"), and Fundacio Bancaixa (P1.1B2011-50). S.G. acknowledges support by MINECO of Spain under the Ramon y Cajal programme. The SCIC of the University Jaume I de Castello is also acknowledged for the gas analysis measurements. C.S. acknowledges the POSDRU/89/1.5/S/58852 Project "Postdoctoral programme for training scientific researchers", co-financed by the European Social Fund within the Sectorial Operational Program Human Resources Development 2007-2013. We want to acknowledge Prof. J. Bisquert for the fruitful discussions related to this manuscript.Trevisan, R.; Rodenas, P.; González-Pedro, V.; Sima, C.; Sánchez, RS.; Barea, EM.; Mora-Sero, I.... (2013). Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based "Quasi-Artificial Leaf". Journal of Physical Chemistry Letters. 4(1):141-146. https://doi.org/10.1021/jz301890mS1411464

Hybrid Electrolyte System

A hybrid electrolyte system for fuel cells and other electrochemical reactors comprising an acid electrolyte, a base electrolyte, and a proton permeable dense phase separating the acid electrolyte from the base electrolyte.Sponsorship: Illinois Institute of TechnologyUnited States Paten