Designing materials for electrochemical carbon dioxide recycling

Electrochemical carbon dioxide recycling provides an attractive approach to synthesizing fuels and chemical feedstocks using renewable energy. On the path to deploying this technology, basic and applied scientific hurdles remain. Integrating catalytic design with mechanistic understanding yields scientific insights and progresses the technology towards industrial relevance. Catalysts must be able to generate valuable carbon-based products with better selectivity, lower overpotentials and improved current densities with extended operation. Here, we describe progress and identify mechanistic questions and performance metrics for catalysts that can enable carbon-neutral renewable energy storage and utilization

On the classical-quantum correspondence for the scattering dwell time

Using results from the theory of dynamical systems, we derive a general expression for the classical average scattering dwell time, tau_av. Remarkably, tau_av depends only on a ratio of phase space volumes. We further show that, for a wide class of systems, the average classical dwell time is not in correspondence with the energy average of the quantum Wigner time delay.Comment: 5 pages, 1 figur

Post-traumatic malunion of the proximal phalanx of the finger. Medium-term results in 24 cases treated by "in situ" osteotomy

We report the clinical and radiographic medium-term results obtained for 20 patients (24 fingers) treated surgically for post-traumatic malunion of the proximal phalanx of the finger. In all cases we performed a corrective osteoclasia or osteotomy at the site of malunion, followed by miniplate and screw fixation or by screw fixation only. The corrective osteoclasia was performed when malalignment was addressed within six weeks after injury. Two patients who had two fractures underwent additional surgery (tenolysis and/or capsulolysis) to improve function and ROM. At the final follow-up, at a mean of 24 months after corrective surgery, good or excellent clinical and radiographic results were obtained in all the patients. The pseudoclaw deformity disappeared in all cases in which a volar angulation deformity was present. An average improvement of about 30% in the range of motion of the MP and PIP joints was observed; only 4 patients complained of mild pain at the maximum degrees of articular excursion of the MP and PIP joints. All the patients presented an improvement in grip strength. The mean DASH score in our series was 5 points. In two of the four cases treated by an intra-articular corrective osteotomy, mild radiographic signs of osteoarthritis at the MP joint were present. The data for this study confirm that "in situ" osteotomy stabilized by miniplates and/or screws is an effective procedure to correct post-traumatic malunions of the proximal phalanges of the fingers

Carbon stock and dynamics in natural regeneration in managed forest in the central Amazon.

Estoque e dinâmica do carbono na regeneração natural em floresta manejada na Amazônia Central. Cerca de 2% da biomassa viva acima do solo encontra-se na regeneração natural das espécies arbóreas. Apesar de ser um valor relativamente baixo, o diagnóstico do estrato inferior da floresta é importante no contexto atual das mudanças climáticas. O objetivo desse estudo foi avaliar os efeitos do manejo florestal no estoque e na dinâmica de carbono da regeneração natural 20 anos após a exploração em floresta na Amazônia Central. Around 2% of the living biomass above ground is found in the natural regeneration of tree species. Despite being a relatively low value, diagnosing the lower stratum of the forest is important in the current context of climate change. The aim of this study was to evaluate the effects of forest management on the carbon stock and dynamics of natural regeneration 20 years after logging in a forest in the Central Amazon

Multiple congenital bilateral trigger digits in a 2-year-old child: case report

Trigger finger is a rare condition in children. In this paper, we report on a 2-year-old boy with multiple congenital bilateral trigger digits. The patient had no history of perinatal trauma, viral or bacterial infections, or metabolic disorders. The patient was treated with physiotherapy for one year. At the one-year follow-up, the boy presented with six trigger fingers (3 on the right hand, 3 on the left hand). Neither thumb was involved. The six trigger fingers were treated surgically: first, the right-hand trigger fingers and, six months later, those of the left hand. After each operation, a 4-week brace in extension was applied to the operated hand. The symptoms were completely resolved after surgical treatment. Many authors have recommended surgical release for the treatment of trigger finger in children; empirical treatment with physiotherapy may be an option when symptoms present or appear at an older age

Sulfur-Modulated Tin Sites Enable Highly Selective Electrochemical Reduction of CO2 to Formate

Electrochemical reduction of carbon dioxide (CO2RR) to formate provides an avenue to the synthesis of value-added carbon-based fuels and feedstocks powered using renewable electricity. Here, we hypothesized that the presence of sulfur atoms in the catalyst surface could promote undercoordinated sites, and thereby improve the electrochemical reduction of CO2 to formate. We explored, using density functional theory, how the incorporation of sulfur into tin may favor formate generation. We used atomic layer deposition of SnSx followed by a reduction process to synthesize sulfur-modulated tin (Sn(S)) catalysts. X-ray absorption near-edge structure (XANES) studies reveal higher oxidation states in Sn(S) compared with that of tin in Sn nanoparticles. Sn(S)/Au accelerates CO2RR at geometric current densities of 55 mA cm−2 at −0.75 V versus reversible hydrogen electrode with a Faradaic efficiency of 93%. Furthermore, Sn(S) catalysts show excellent stability without deactivation (<2% productivity change) following more than 40 hours of operation. With rapid advances in the efficient and cost-effective conversion of sunlight to electrical power, the development of storage technologies for renewable energy is even more urgent. Using renewable electricity to convert CO2 into formate simultaneously addresses the need for storage of intermittent renewable energy sources and the need to reduce greenhouse gas emissions. We report an increase of greater than 4-fold in the current density (hence the rate of reaction) in formate electrosynthesis compared with relevant controls. Our catalysts also show excellent stability without deactivation (<2% productivity change) following more than 40 hours of operation. The electrochemical reduction of carbon dioxide (CO2RR) offers a compelling route to energy storage and high-value chemical manufacture. The presence of sulfur atoms in catalyst surfaces promotes undercoordinated sites, thereby improving the electrochemical reduction of CO2 to formate. The resulting sulfur-modulated tin catalysts accelerate CO2RR at geometric current densities of 55 mA cm−2 at −0.75 V versus RHE with a Faradaic efficiency of 93%

Governança ágil em TIC: rompendo paradigmas

This paper presents the basis of the Agile Governance in Information and Communication Technology (ICT), which is based on Agile Software Engineering Methodologies principles and values. Its development was done through a systematic review process, supported by Bibliometrics and Scientometrics methods and techniques, where the Critical Success Factors (CSF) of ICT Governance projects and the principles of the Agile Manifesto were analyzed. Next, through an inductive approach, focused on the convergence between the concepts involved, it was analyzed how agile principles could help to minimize the gap between ICT and business. Evidences of their occurrence were taken through a Conceptual Survey Research. As a result, the foundations and concepts of Agile Governance in ICT were defined and, finally, the development of a reference model was proposed as a future work.Este artigo apresenta as bases do conceito de Governança Ágil em TIC - Tecnologia da Informação e Comunicação - , baseado nos princípios e valores das Metodologias Ágeis da Engenharia de Software. O desenvolvimento deste trabalho se deu através de um processo de Revisão Sistemática, apoiado em técnicas e métodos Bibliométricos e Cienciométricos, no qual foram analisados os Fatores Críticos de Sucesso (FCS) de projetos de Governança em TIC e os princípios das Metodologias Ágeis. Em seguida, através de uma abordagem indutiva, com foco na convergência entre os conceitos envolvidos, analisou-se como os princípios ágeis poderiam contribuir para minimizar o hiato existente entre a TIC e o negócio. Evidências da coerência da proposta foram reforçadas através de uma Pesquisa de Sondagem Conceitual. Como resultado, foram definidas as bases em que se fundamentam o conceito de Governança Ágil em TIC e sugerido como trabalho futuro a definição de um modelo de referência para este conceito