Espectroelectroquímica de fotocatalizadores supramoleculares para reducción de co2

La reducción electrocatalítica de CO2 usando complejos de rutenio polipiridilo, Ruα y Ruβ, se estudió por voltamperometría en dimetilformamida DMF con 1M H2O. El primer proceso de reducción para Ruα y Ruβ en DMF: H2O muestra reversibilidad en su respuesta voltamétrica. Los potenciales redox de las ondas son -0.64 V (α) y -0.60 V (β) (vs Ag/AgCl). La corriente de la onda catódica para Ruα y Ruβ se incrementa con la adición de CO2 a la solución lo que indica reducción catalítica de CO2 en -0.60 V y -0.57 V respectivamente. La presencia de un sitio reactivo de nitrógeno en el ligando ptpb (4,5,9,11,14 -pentaaza-benzo(α o β)-trifenileno) facilita la formación de un intermediario tipo carbamato. Se describen reflectancias diferenciales, R/R vs. potencial en N2 y CO2, a 575 y 564 nm empleadas para seguir la formación de las especies radicales monoreducidas Ruα•- and Ruβ•-A combination of electro and spectroelectrochemistry have been used to study the electrocatalytic reduction of CO2 in the presence of ruthenium polypyridyl, Ru and Ruβ, complexes. Measurements were conducted in DMF:H2O. The first redox processes for Ruα and Ruβ show reversible voltammetric waves at -0.64 V and -0.60 V vs Ag/AgCl respectively. A clear increase in the cathodic wave of both Ruα and Ruβ occurs when CO2 is added to the solution pointing to a catalytic wave of the CO2 reduction at -0.60 V and -0.57 V respectively. The presence of a reactive nitrogen site on the ptpb (4,5,9,11,14 -pentaaza-benzo(α o β) -triphenylene) (either α or β) ligand facilitates the formation of a CO2 carbamate-type intermediate. Differential reflectance, R/R, vs. potential profiles in N2 and CO2 solutions show the consumption of the complex radical anion in the presence of CO2. R/R /potential curves are shown at 575 and 564 nm to track the electrochemical evolution of monoreduced Ruα •- and Ruβ •- radicals respectivelyFil: Franco Pachon, Yeimi Milena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Tacconi, Norma. University Of Texas; Estados UnidosFil: MacDonnell, Frederick M.. University Of Texas; Estados UnidosFil: Lezna, Reynaldo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Driving multi-electron reactions with photons: dinuclear ruthenium complexes capable of stepwise and concerted multi-electron reduction

Using biological precedents, it is expected that concerted, multi-electron reduction processes will play a significant role in the development of efficient artificial photosynthetic systems. We have found that the dinuclear ruthenium complexes [(phen)₂Ru(tatpp)Ru(phen)₂⁴⁺ (P) and [(phen)₂Ru(tatpq) Ru(phen)₂]⁴⁺ (Q) undergo photodriven 2- and 4-electron reductions, respectively, in the presence of a sacrificial reductant. Importantly, these processes are completely reversible upon exposure to air, and consequently, these complexes have the potential to be used catalytically in multi-electron transfer reactions. A localized molecular orbital description of the ligands and complexes is used to explain both the function and spectroscopy of these complexes. In both complexes, the reducing equivalents are stored in the π* orbitals of the bridging ligands and depending on the solution pH, various protonation states of the reduced species of P and Q are obtained. Under basic conditions, the photochemical pathway favors sequential single-electron reductions, while neutral or slightly acidic conditions give rise to proton-coupled multi-electron transfer. In fact, at sufficiently acidic pH, only a coupled two-electron, 2-proton process is seen. Few molecular photocatalysts are capable of proton-coupled multi-electron transfer, which is believed to be a fundamental component of light-activated energy storage in nature.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Espectroelectroquímica de fotocatalizadores supramoleculares para reducción de CO<SUB>2</SUB>

La reducción electrocatalítica de CO2 usando complejos de rutenio polipiridilo, Ruα y Ruβ, se estudió por voltamperometría en dimetilformamida DMF con 1M H2O. El primer proceso de reducción para Ruα y Ruβ en DMF: H2O muestra reversibilidad en su respuesta voltamétrica. Los potenciales redox de las ondas son -0.64 V (α) y -0.60 V (β) (vs Ag/AgCl). La corriente de la onda catódica para Ruα y Ruβ se incrementa con la adición de CO2 a la solución lo que indica reducción catalítica de CO2 en -0.60 V y -0.57 V respectivamente. La presencia de un sitio reactivo de nitrógeno en el ligando ptpb (4,5,9,11,14 -pentaaza-benzo(α o β)-trifenileno) facilita la formación de un intermediario tipo carbamato. Se describen reflectancias diferenciales, R/R vs. potencial en N2 y CO2, a 575 y 564 nm empleadas para seguir la formación de las especies radicales monoreducidas Ruα•- and Ruβ•-A combination of electro and spectroelectrochemistry have been used to study the electrocatalytic reduction of CO2 in the presence of ruthenium polypyridyl, Ru and Ruβ, complexes. Measurements were conducted in DMF:H2O. The first redox processes for Ruα and Ruβ show reversible voltammetric waves at -0.64 V and -0.60 V vs Ag/AgCl respectively. A clear increase in the cathodic wave of both Ruα and Ruβ occurs when CO2 is added to the solution pointing to a catalytic wave of the CO2 reduction at -0.60 V and -0.57 V respectively. The presence of a reactive nitrogen site on the ptpb (4,5,9,11,14 -pentaaza-benzo(α o β) -triphenylene) (either α or β) ligand facilitates the formation of a CO2 carbamate-type intermediate. Differential reflectance, R/R, vs. potential profiles in N2 and CO2 solutions show the consumption of the complex radical anion in the presence of CO2. R/R /potential curves are shown at 575 and 564 nm to track the electrochemical evolution of monoreduced Ruα •- and Ruβ •- radicals respectivelyInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Targeting Protein Homeostasis in Sporadic Inclusion Body Myositis

Sporadic inclusion body myositis (sIBM) is the commonest severe myopathy in patients over age 50. Previous therapeutic trials have targeted the inflammatory features of sIBM, but all have failed. Since protein dyshomeostasis may also play a role in sIBM, we tested the effects of targeting this feature of the disease. Using rat myoblast cultures, we found that up-regulation of the heat shock response with Arimoclomol reduced key pathological markers of sIBM in vitro. Furthermore, in mutant valosin-containing protein VCP mice, which develop an inclusion body myopathy (IBM), treatment with Arimoclomol ameliorated disease pathology and improved muscle function. We therefore evaluated the safety and tolerability of Arimoclomol in an investigator-lead, randomised, double-blind, placebo-controlled, proof-of-concept patient trial and gathered exploratory efficacy data which showed that Arimoclomol was safe and well tolerated. Although Arimoclomol improved some IBM-like pathology in vitro and in vivo in the mutant VCP mouse, we did not see statistically significant evidence of efficacy in this proof of concept patient trial

Genome Sequence Analysis of Dengue Virus 1 Isolated in Key West, Florida

Dengue virus (DENV) is transmitted to humans through the bite of mosquitoes. In November 2010, a dengue outbreak was reported in Monroe County in southern Florida (FL), including greater than 20 confirmed human cases. The virus collected from the human cases was verified as DENV serotype 1 (DENV-1) and one isolate was provided for sequence analysis. RNA was extracted from the DENV-1 isolate and was used in reverse transcription polymerase chain reaction (RT-PCR) to amplify PCR fragments to sequence. Nucleic acid primers were designed to generate overlapping PCR fragments that covered the entire genome. The DENV-1 isolate found in Key West (KW), FL was sequenced for whole genome characterization. Sequence assembly, Genbank searches, and recombination analyses were performed to verify the identity of the genome sequences and to determine percent similarity to known DENV-1 sequences. We show that the KW DENV-1 strain is 99% identical to Nicaraguan and Mexican DENV-1 strains. Phylogenetic and recombination analyses suggest that the DENV-1 isolated in KW originated from Nicaragua (NI) and the KW strain may circulate in KW. Also, recombination analysis results detected recombination events in the KW strain compared to DENV-1 strains from Puerto Rico. We evaluate the relative growth of KW strain of DENV-1 compared to other dengue viruses to determine whether the underlying genetics of the strain is associated with a replicative advantage, an important consideration since local transmission of DENV may result because domestic tourism can spread DENVs

Feedback as intervention for team learning in virtual teams: the role of team cohesion and personality

Scholars and practitioners agree that virtual teams (VTs) have become commonplace in today's digital workplace. Relevant literature argues that learning constitutes a significant contributor to team member satisfaction and performance, and that, at least in face-to-face teams, team cohesion fosters team learning. Given the additional challenges VTs face, e.g. geographical dispersion, which are likely have a negative influence on cohesion, in this paper we shed light on the relationship between team cohesion and team learning. We adopted a quantitative approach and studied 54 VTs in our quest to understand the role of feedback in mediating this relationship and, more specifically, the role of personality traits in moderating the indirect effect of team feedback and guided reflection intervention on TL through team cohesion within the VT context. Our findings highlight the importance of considering aspects related to the team composition when devising intervention strategies for VTs, and provide empirical support for an interactionist model between personality and emergent states such as cohesion. Implications for theory and practice are also discussed

Modelling to bridge many boundaries: the Colorado and Murray-Darling River basins

Increasing pressure on shared water resources has often been a driver for the development and utilisation of water resource models (WRMs) to inform planning and management decisions. With an increasing emphasis on regional decision-making among competing actors as opposed to top-down and authoritative directives, the need for integrated knowledge and water diplomacy efforts across federal and international rivers provides a test bed for the ability of WRMs to operate within complex historical, social, environmental, institutional and political contexts. This paper draws on theories of sustainability science to examine the role of WRMs to inform transboundary water resource governance in large river basins. We survey designers and users of WRMs in the Colorado River Basin in North America and the Murray-Darling Basin in southeastern Australia. Water governance in such federal rivers challenges inter-governmental and multi-level coordination and we explore these dynamics through the application of WRMs. The development pathways of WRMs are found to influence their uptake and acceptance as decision support tools. Furthermore, we find evidence that WRMs are used as boundary objects and perform the functions of ‘boundary work’ between scientists, decision-makers and stakeholders in the midst of regional environmental changes

Dilated Cardiomyopathy with Increased SR Ca2+ Loading Preceded by a Hypercontractile State and Diastolic Failure in the α1CTG Mouse

Mice over-expressing the α1−subunit (pore) of the L-type Ca2+ channel (α1CTG) by 4months (mo) of age exhibit an enlarged heart, hypertrophied myocytes, increased Ca2+ current and Ca2+ transient amplitude, but a normal SR Ca2+ load. With advancing age (8–11 mo), some mice demonstrate advanced hypertrophy but are not in congestive heart failure (NFTG), while others evolve to frank dilated congestive heart failure (FTG). We demonstrate that older NFTG myocytes exhibit a hypercontractile state over a wide range of stimulation frequencies, but maintain a normal SR Ca2+ load compared to age matched non-transgenic (NTG) myocytes. However, at high stimulation rates (2–4 Hz) signs of diastolic contractile failure appear in NFTG cells. The evolution of frank congestive failure in FTG is accompanied by a further increase in heart mass and myocyte size, and phospholamban and ryanodine receptor protein levels and phosphorylation become reduced. In FTG, the SR Ca2+ load increases and Ca2+ release following excitation, increases further. An enhanced NCX function in FTG, as reflected by an accelerated relaxation of the caffeine-induced Ca2+ transient, is insufficient to maintain a normal diastolic Ca2+ during high rates of stimulation. Although a high SR Ca2+ release following excitation is maintained, the hypercontractile state is not maintained at high rates of stimulation, and signs of both systolic and diastolic contractile failure appear. Thus, the dilated cardiomyopathy that evolves in this mouse model exhibits signs of both systolic and diastolic failure, but not a deficient SR Ca2+ loading or release, as occurs in some other cardiomyopathic models