Metal oxides and the thermochemical storage of solar energy

ABSTRACT: Metal oxides are used in concentrated solar energy plants (CSP) to store heat, which can be used in the absence of the sun to generate electricity or produce solar fuels. Energy can be stored in this form for long periods, being released when necessary. Two step redox thermochemical cycles using metal oxides are a valuable solar energy storage option to produce H2 and CO. This brief review paper summarizes the role of metal oxide on the sustainable production of alternative fuels. It contemplates the formation of oxygen vacancies, combination of metals and the progress made to date on the utilization of metal oxides as promising materials with potential application in water splitting for production of clean hydrogen and solar fuels.info:eu-repo/semantics/publishedVersio

Influence of the electrolyte on the electrochemical performance of a polyimide material for electrodes in rechargeable batteries

The charge storage on organic polymers has led to increasing application of these new materials such as active electrodes in rechargeable batteries [1, 2]. Taking advantage of the redox properties of aromatic polyimide imide group [3], which allows it to be electrochemically oxidized and reduced reversibly, we will present the advances made on the electrochemical studies carried out with a polyimide derivative electrode material towards the constitution of a new battery. Previous studies by the authors with a poliimide derivative [4]using cyclic voltammetry have shown their significant redox capacity to be applied as an alternative material for energy storage in rechargeable batteries. Furthermore, the use of polyimide is considered safe owing to this type of polymer not being flammable and having an excellent thermal stability and high mechanical strength. Since the polyimide is hydrolyzable, its use can be considered environmentally favorable. Attempts to use composite poliimides through solvent blending methodologies lead to poor dispersion of the polymer in the composite mixture. In situ polymerization techniques were well succeed with added incorporation of carbon fibre with the poliimide precursor. Research is in progress with studies with different electrolytes and polyimide composite in order to ensure an efficient lithium ion exchange and obtain batteries with satisfying energy performance. Advances made will be presented herein

Electrochemical performance of organic electroactive materials for application in rechargeable batteries

Rechargeable batteries consisting of organic base electrodes are increasingly being studied as an alternative to conventional inorganic electrodes. The approach adopted in this work involves the development of new cathode organic materials based on polyimide derivatives with significant redox potential or capacity in order to increase stability and improve the energy density of current lithium ion cells. Preparation of organic polymeric polyimides was carried out, followed by their integration in an electrode structure that uses carbon nanofibers, as a support and as a means to increase conductivity. An electrochemical study based on cyclic voltammetry was conducted in order to evaluate the performance and redox capacity of the electrodes. The implemented strategy is based on the fact that the aromatic imide group may be electrochemically reduced and oxidized in a reversible manner, with each molecule of polyimide being able to transfer four electrons in two steps, accounting for a high specific capacity of the electrodes. Some of the composite electrodes studied in this work demonstrated good redox capacity, stability under potential cycling and higher current densities, 10-20X, than those reported in the literatures for similar compounds

An electrochemical process for the production of synthetic fuels at low temperatures [Resumo]

Following work exploring the low temperature electrolysis in alkaline media, using graphite consumable anodes, from which syngas was obtained1, laboratory studies have been conducted in acid media pursuing higher efficiency in the production of hydrogen and synthetic fuels. Experiments were conducted in an own designed undivided planar cell with 25 cm2 geometrical area electrodes using a 0.5 M H2SO4 solution with and without Fe(II) additions. Fe2+ oxidizes to Fe3+ at the anode surface. The redox couple Fe3+/ Fe2+ acts as an oxidation mediator not only oxidizing the bulk and detached graphite but also the surface functional groups. The practical experimental potential for graphite oxidation is within the range for the electroxidation of the Fe redox couple giving as a result a 4-fold increase in the amount of produced CO2 at near room temperature, when using 0.025 M FeSO4

Synthetic fuels production by graphite-assisted electrolysis

ABSTRACT: Hydrogen produced by water electrolysis is considered as the best energy carrier to adjust the balance between the generation of power source by renewable primary energy and energy demand for end-use. Further advantages are foreseen with the use of carbon-assisted electrolysis. This is due to the electrochemical participation of carbon in the reaction, the electrolysis process would potentially require about 1/3 the electrical energy with the balance of 2/3 coming from the chemical energy of carbon in comparison with conventional water electrolysis where all the energy input is electric. Carbon is oxidized to CO2 on the anode and hydrogen is produced at the cathode. Generally, carbon sources for anodic reaction are graphite, activated carbon and coal. In this work, low temperature electrochemical gasification of graphite in alkaline and acid solutions was explored, taking into account experimental conditions where the faradaic overall current has a significant contribution from carbon oxidation reactions. Results indicate adequate molar gases fraction for the production of syngas and the production of small chain hydrocarbons, obtained at laboratory prototype level.N/

Os ciclos termoquímicos e o armazenamento de energia solar térmica

ABSTRACT: The increasing contribution of renewables to the grid reduces the participation of conventional energy sources. However, due to the reduced capability of storing electricity, wind and photovoltaic energy have limitations in the flexibility of the electricity grid. Solar thermal power plants use concentrated solar energy to produce electricity and allow energy storage, essential for balancing energy demand between day and night or during periods of intermittent sunlight. This paper focusses on thermochemical energy storage as a way to efficiently store high temperature solar heat in the form of chemical bonds of stable and safe solid materials. The existing high concentration solar thermal technologies are summarized and the thermochemical cycles using metal oxides are discussed in particular, as a promising form of thermochemical storage for the production of electricity and solar fuels. Solar energy stored in the form of solar fuels offers as main advantages the fact that it is transportable and can be stored for long periods.RESUMO: A contribuição crescente das energias renováveis na rede elétrica faz diminuir a participação das fontes de energia convencionais. Contudo, devido à reduzida capacidade de armazenamento de eletricidade, as energias eólica e fotovoltaica têm limitações na flexibilidade da rede elétrica. As centrais térmicas solares usam energia solar concentrada durante as horas de luz solar para produzir eletricidade e permitir o armazenamento de energia, fundamental para equilibrar a procura de energia entre o dia e a noite ou durante períodos de luz solar inte rmitente. O armazenamento termoquímico de energia é uma forma de armazenar eficientemente calor solar a temperatura elevada, na forma de ligações químicas de materiais sólidos estáveis e seguros. Neste artigo apresentam-se, de forma sumária, as tecnologias de alta concentração solar existentes e descreve-se, em particular, o armazenamento de energia térmica através dos ciclos termoquímicos usando óxidos metálicos, uma forma promissora de armazenamento de energia para a produção de eletricidade e combustíveis solares. A energia solar armazenada na forma de combustíveis solares oferece como principais vantagens, o facto de ser transportável e poder ser armazenada por longos períodos de tempo.info:eu-repo/semantics/publishedVersio

Juventudes de direita e de esquerda em perspectiva comparada Brasil e Argentina

This research performs an analysis on the political perceptions of young Brazilians and Argentines about democracy and political institutions considering their positions as right, left and center in the political and ideological aspect. For this purpose, we selected and analyzed data only on young people, taken from the Latinobarômetro bank in its 2020 wave. Specifically, we analyzed ideological identification, socioeconomic profile (race and religion), evaluation of democracy, preference for authoritarian governments, evaluation of institutions and interest in politics. Among the results, we highlight how the distribution of young people between right and left is approximate, with a high percentage of young people who positioned themselves in the center. Also noteworthy is the greater support for democracy among right-wing youth, as well as interest in politics.Esta pesquisa analisa as percepções políticas dos jovens brasileiros e argentinos acerca da democracia e das instituições políticas, considerando seus posicionamentos próprios como de direita, esquerda e centro no aspecto político e ideológicos. Para tanto, selecionamos e analisamos dados somente sobre os jovens, retirados do banco do Latinobarómetro em sua onda de 2020. Especificamente verificamos a identificação ideológica, perfil socioeconômico (raça e religião), avaliação da democracia, preferência por governos autoritários, avaliação das instituições e interesse por política. Dentre os resultados destacamos como a distribuição dos jovens entre direita e esquerda é aproximada, com um alto percentual de jovens que se posicionaram ao centro. Destaca-se também o maior apoio a democracia entre os jovens de direita, bem como o interesse por política

Female emancipation in a male dominant, sexually dimorphic primate under natural conditions

In most group-living animals, a dominance hierarchy reduces the costs of competition for limited resources. Dominance ranks may reflect prior attributes, such as body size, related to fighting ability or reflect the history of self-reinforcing effects of winning and losing a conflict (the winner-loser effect), or both. As to prior attributes, in sexually dimorphic species, where males are larger than females, males are assumed to be dominant over females. As to the winner-loser effect, the computational model DomWorld has shown that despite the female’s lower initial fighting ability, females achieve some degree of dominance of females over males. In the model, this degree of female dominance increases with the proportion of males in a group. This increase was supposed to emerge from the higher fraction of fights of males among themselves. These correlations were confirmed in despotic macaques, vervet monkeys, and in humans. Here, we first investigate this hypothesis in DomWorld and next in long-term data of 9,300 observation hours on six wild groups of robust capuchin monkeys (Sapajus libidinosus; S. nigritus, and S. xanthosternos) in three Brazilian sites. We test whether both the proportion of males and degree of female dominance over males are indeed associated with a higher relative frequency of aggression among males and a higher relative frequency of aggression of females to males. We confirm these correlations in DomWorld. Next, we confirm in empirical data of capuchin monkeys that with the proportion of males in the group there is indeed an increase in female dominance over males, and in the relative frequency of both male-male aggression and aggression of females to males and that the female dominance index is significantly positively associated with male male aggression. Our results reveal that adult sex ratio influences the power relation between the sexes beyond predictions from socioecological models.</p

Rede de atenção às urgências e emergências e a produção viva de mapas de cuidado: Relatório técnico-científico final

Objetivo: analisar o processo de implementação e conformação dos modos de produção do cuidado da política de Rede de Atenção às Urgências e Emergências (RUE), em duas regiões de saúde: Campinas (SP) e Passo Fundo (RS). Procura, ainda, identificar analisadores da produção micropolítica presentes no processo de pactuação e implementação da RUE nessas regiões; analisar as possíveis mudanças no processo de gestão a partir da implementação das RUE; e caracterizar as transformações ocorridas nos modos de produção do cuidado em saúde a partir da implementação das RUE. Metodologia: a pesquisa tem caráter qualitativo, com abordagem micropolítica, e caracteriza-se como estudo de caso e foi desenvolvida através de revisão de literatura, análise de documentos oficiais, coleta de depoimentos de gestores municipais e estaduais, entrevistas narrativas com usuários, e entrevistas em profundidade com gerentes de serviços. No total, foram entrevistados 61 sujeitos. A análise teve como referência a ‘Abordagem do Ciclo de Políticas’. A pesquisa foi desenvolvida por pesquisadores dos programas de Pós-Graduação em Saúde Coletiva da Escola Paulista de Medicina – Universidade Federal de São Paulo (Unifesp-EPM) e da Imed-Faculdade Meridional de Passo Fundo (RS), com apoio de gestores regionais e municipais de saúde e dos Conselhos de Secretários Municipais de Saúde (COSEMS) dos estados de São Paulo e do Rio Grande do Sul. Resultados: Os principais resultados apontam para uma política pública de caráter plural e multifacetado, formulada a partir de diversas influências sociais, econômicas, políticas e teóricas, que expressa como intencionalidade a ampliação do acesso e o cuidado integral em situações de urgência e emergência em saúde. No contexto da prática, apesar da ênfase aos aspectos organizativos e ao financiamento, é observada a política ‘em cena’ onde podem ser identificadas ações de gestão e de produção de cuidado induzidas pela política, mantidas apesar da política e produzidas para além da política da RUE. A relação entre a política oficial e a ação micropolítica dos gestores, tornou-a uma produção singular no campo da governança regional; a necessidade de autonomia dos usuários e a dimensão do cuidado familiar apontam para caminhos na construção da integralidade; há evidências de produções vivas induzidas pela política que qualificam o cuidado, embora iniquidades sejam mantidas ou produzidas; e, a necessidade de articulação entre os componentes em rede, embora evocada, traduz-se em conexões frágeis e não regulares. Considerações Finais: A compreensão dos complexos processos que envolvem as políticas públicas de saúde, os interesses e poderes que as atravessam, tem potencial para fortalecer os atores implicados com a luta pela promoção da equidade em saúde e pela justiça social.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)428431/2018-