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

Feasibility of the reaction between ( R )-3-hydroxybutyrate & hydroxyl radicals

Energetic particles and secondary radiation encountered by astronauts during space flight result in the formation of a range of reactive oxygen species, including hydroxyl radicals (HO˙), which can lead to premature cell death. Several strategies have been proposed to combat the intracellular effects of radiation including use of exogeneous antioxidants. We have investigated the reaction between the major ketone body (R)-3-hydroxybutyrate (HB−) and HO˙ at the SMD/M062X/6-311++G(d,p) level of theory. This revealed a bimolecular rate constant of 6.20 × 109 dm3 mol−1 s−1 with hydrogen atom abstraction at the hydroxyalkyl C–H bond constituting the predominate reaction channel (Γ ≈ 30%). Proton coupled electron transfer between the hydroxyl group and HO˙ was thermodynamically and kinetically the least favourable (k = 8.20 × 107 dm3 mol−1 s−1, Γ ≈ 1.3%) but produced an oxygen-centred radical exhibiting SOMO–HOMO inversion. Hydrogen abstraction at the methylene (k ≈ 1 × 109 dm3 mol−1 s−1, Γ ≈ 20%) and methyl (k ≈ 6 × 108 dm3 mol−1 s−1, Γ ≈ 10%) sites was of intermediate reactivity. Our estimates show that in dietary ketosis the half-life of HO˙ is shorter on reaction with HB− than ascorbate (t½ = 3.73 × 10−8 vs. 4.81 × 10−7 s) suggesting that this is a viable approach for reducing the cellular impact of ionising radiation

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

Incidence and phenotypes of childhood-onset genetic epilepsies:a prospective population-based national cohort

Epilepsy is common in early childhood. In this age group it is associated with high rates of therapy-resistance, and with cognitive, motor, and behavioural comorbidity. A large number of genes, with wide ranging functions, are implicated in its aetiology, especially in those with therapy-resistant seizures. Identifying the more common single-gene epilepsies will aid in targeting resources, the prioritization of diagnostic testing and development of precision therapy. Previous studies of genetic testing in epilepsy have not been prospective and population-based. Therefore, the population-incidence of common genetic epilepsies remains unknown. The objective of this study was to describe the incidence and phenotypic spectrum of the most common single-gene epilepsies in young children, and to calculate what proportion are amenable to precision therapy. This was a prospective national epidemiological cohort study. All children presenting with epilepsy before 36 months of age were eligible. Children presenting with recurrent prolonged (>10 min) febrile seizures; febrile or afebrile status epilepticus (>30 min); or with clusters of two or more febrile or afebrile seizures within a 24-h period were also eligible. Participants were recruited from all 20 regional paediatric departments and four tertiary children’s hospitals in Scotland over a 3-year period. DNA samples were tested on a custom-designed 104-gene epilepsy panel. Detailed clinical information was systematically gathered at initial presentation and during follow-up. Clinical and genetic data were reviewed by a multidisciplinary team of clinicians and genetic scientists. The pathogenic significance of the genetic variants was assessed in accordance with the guidelines of UK Association of Clinical Genetic Science (ACGS). Of the 343 patients who met inclusion criteria, 333 completed genetic testing, and 80/333 (24%) had a diagnostic genetic finding. The overall estimated annual incidence of single-gene epilepsies in this well-defined population was 1 per 2120 live births (47.2/100 000; 95% confidence interval 36.9–57.5). PRRT2 was the most common single-gene epilepsy with an incidence of 1 per 9970 live births (10.0/100 000; 95% confidence interval 5.26–14.8) followed by SCN1A: 1 per 12 200 (8.26/100 000; 95% confidence interval 3.93–12.6); KCNQ2: 1 per 17 000 (5.89/100 000; 95% confidence interval 2.24–9.56) and SLC2A1: 1 per 24 300 (4.13/100 000; 95% confidence interval 1.07–7.19). Presentation before the age of 6 months, and presentation with afebrile focal seizures were significantly associated with genetic diagnosis. Single-gene disorders accounted for a quarter of the seizure disorders in this cohort. Genetic testing is recommended to identify children who may benefit from precision treatment and should be mainstream practice in early childhood onset epilepsy

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

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

Reversible multi-electron reduction of 9,11,20,22-tetraaza-tetrapyridopentacene (tatpp) as axial ligand in the [(bpy)2ru(tatpp)]cl2 complex

The ruthenium complex, [(bpy)2Ru(tatpp)]2+ (12+; bpy is 2,2’-bipyridine where tatpp is 9,11,20,22-tetraaza tetrapyrido[3,2-a:2’3’-c:3”,2”-l:2”’,3”’]-pentacene) is a promising candidate for homogeneous solar photocatalysis, based on the coupling of light absorption by the (bpy)2Ru2+ chromophore moiety with the tatpp ability to receive and reversible store electrons in aqueous media. In the present communication, a combination of spectroelectrochemistry and voltammetry was applied to compare the electroreduction processes of tatpp in complex 12+ and as a Zn-tatpp adduct. For complex 12+, the radical [(bpy)2Ru(tatpp•-)]+(1•+) is the first electroreduced species that then converts to doubly-reduced, single-protonated [(bpy)2Ru(Htatpp-)]+ (H1+) and doubly-protonated [(bpy)2Ru(H2tatpp)]2+(H212+) by subsequent electron transfer (ET) and proton transfer (PT) reactions. Contrastingly, spectroelectrochemistry of the Zn-tatpp adduct showed negligible amounts of intermediate tatpp•- radical and dominance of double reduced Zn-(Htatpp-) and Zn(H2tatpp) species. Upon further electroreduction, doubly-reduced species form quadruply reduced, protonated species, in both systems. The four electrons uptake in complex 12+ is followed by a rapid homogeneous comproportionation reaction with the initial 12+ reactant leading to the regeneration of intermediate double-reduced species, H212+, while no comporportionation occurs for Zn-tatpp because the reduced species are film-confined, that is, restrained to move to the bulk solution for encounter with the initial reactant.El complejo de rutenio, [(bpy)2Ru(tatpp)]2+ (12+; bpy es 2,2’-bipiridilo donde tatpp es 9,11,20,22-tetraaza tetrapirido[3,2-a:2’3’-c:3”,2”-l:2”’,3”’]-pentaceno,) es un candidato promisorio para fotocatálisis solar homogénea, considerando su habilidad para acoplar la absorción de luz por medio del cromóforo (bpy)2Ru2+ con la propiedad del grupo tatpp para recibir y almacenar reversiblemente electrones en medio acuoso. En este trabajo se empleó una combinación de espectroelectroquímica y voltametría para comparar los procesos de electroreducción de tatpp en el complejo 12+y en el aducto Zn-tatpp. En el caso del complejo 12+, el radical [(bpy)2Ru(tatpp•-)]+(1•+) es el primer producto electroreducido que luego da lugar a la especie doble reducida, monoprotonada [(bpy)2Ru(Htatpp-)]+ (H1+) y a la doble protonada [(bpy)2Ru(H2tatpp)]2+(H212+) por reacciones de transferencia de electrones (ET) y de protones (PT). Por el contrario, la espectroelectroquímica del aducto Zn-tatpp mostró cantidades mínimas del intermediario radical tatpp•- con predominancia de las especies Zn-(Htatpp-) y Zn(H2tatpp). En una electroreducción adicional las especies doble reducidas forman, en ambos sistemas, especies protonadas cuadruple reducidas. El almacenamiento de cuatro electrones en el complejo 12+es seguido por una rápida comproporcionación homogénea con el reactivo inicial 12+conduciendo a la regeneración del intermediario doble reducido H212+mientras que Zn-tatpp no muestra tal comproporcionación debido a que las especies reducidas se encuentran confinadas en una película adsorbida, impedidas de moverse hacia el seno de la solución para reaccionar con el reactivo inicial.Instituto 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