5 research outputs found
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Mass-transport resistances of acid and alkaline ionomer layers: A microelectrode study part 1 - Microelectrode development
The use of microelectrodes to study localized mass-transport phenomena in fuel-cell catalyst layers is an increasingly valuable tool. However, existing microelectrode cells have been used in static, equilibrated environment modes with poorly controlled interfaces. In this work, we present a microelectrode cell design that expands the experimental space addressable by microelectrodes to include mechanical pressure, gas flow and ionomer medium, and experimental throughput. The feasibility of the design is examined for fuel-cell reactions, with oxygen reduction currents independent of mechanical pressure and gas flowrate. Finally, cell equilibration time and IR drop across the electrolyte are estimated. The new cell design is robust and provides a consistent base from which to perform more complicated studies examining mass-transport properties of ionomers and/or the electrochemical reaction kinetics of hydrogen oxidation and oxygen reduction
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Method-Using microelectrodes to explore solid polymer electrolytes
Solid polymer electrolytes are an emerging technology in electrochemistry driven by their use in energy applications such as fuel cells, electrolyzers, and solid-state batteries. Compared to traditional liquid electrolytes, solid polymer electrolytes provide safer, cheaper, and potentially improved device performance. However, there is a lack of standard experimental methods for studying solid electrolytes. Microelectrodes have inherent benefits capable of filling this experimental gap due primarily to their integration into model electrochemical cells with solid electrolytes that represent complex interfaces, enabling additional insight into reaction processes. In this tutorial review, we explore the use of microelectrodes to study solid polymer electrolytes, beginning with a brief history of the field including common experimental cell designs and their benefits and drawbacks. Methods of evaluating essential kinetic and mass-transport parameters are then examined. In addition, the key studies of the past 30 years utilizing microelectrode cells and solid polymer electrolytes are summarized, with important results highlighted and compared. Finally, future studies of solid polymer electrolytes with microelectrodes and potential new avenues of research are commented on
Recommended from our members
Mass-transport resistances of acid and alkaline ionomer layers: A microelectrode study part 1 - Microelectrode development
The use of microelectrodes to study localized mass-transport phenomena in fuel-cell catalyst layers is an increasingly valuable tool. However, existing microelectrode cells have been used in static, equilibrated environment modes with poorly controlled interfaces. In this work, we present a microelectrode cell design that expands the experimental space addressable by microelectrodes to include mechanical pressure, gas flow and ionomer medium, and experimental throughput. The feasibility of the design is examined for fuel-cell reactions, with oxygen reduction currents independent of mechanical pressure and gas flowrate. Finally, cell equilibration time and IR drop across the electrolyte are estimated. The new cell design is robust and provides a consistent base from which to perform more complicated studies examining mass-transport properties of ionomers and/or the electrochemical reaction kinetics of hydrogen oxidation and oxygen reduction
Qualidade de medicamentos isentos de prescrição: um estudo com marcas de dipirona comercializadas em uma drogaria de Cascavel (PR, Brasil) Quality of over-the-counter medicines: a study with dipyrone brands commercialized in a drugstore in Cascavel city (Paraná, Brazil)
A dipirona é um fármaco muito utilizado pela população brasileira. É considerado seguro mesmo em gestantes, lactentes e crianças, mas é proibido em alguns países do mundo pelo suposto papel de causar agranulocitose e anemia aplástica. Em 2001, a Agência Nacional de Vigilância Sanitária (Anvisa) considerou que os medicamentos com esse fármaco apresentavam bom risco-benefício em relação a outros de indicação semelhante. Porém, de nada adianta segurança no uso de um medicamento se este é de baixa qualidade. É comum encontrar no mercado brasileiro medicamentos fora dos padrões, o que se constitui em um risco para a população em geral. Dessa forma, foram analisadas sete amostras de marcas diferentes de dipirona solução oral comercializados em uma farmácia de Cascavel (PR). Os resultados demonstram que a fiscalização quanto à qualidade de medicamentos similares precisa ser aprimorada, pois eles foram os que mais apresentaram desvios de qualidade.<br>Dipyrone is an antipyretic and analgesic medicine very used by the Brazilian population. The administration is considered safe even in pregnant women, nurseling and children, but is forbidden in some countries, as supposedly causes agranulocytosis and aplastic anemia. In 2001, National Health Surveillance Agency (Anvisa) approved the commercialization of this medicine in Brazil. However, it does not matter the safeness in the use of a medicine advances, if it does not have quality. Based on this quality, this work was elaborated, that analyzes seven samples of commercialized different marks of dipyrone oral solution in pharmaceutical establishment in the Cascavel city, Paraná, Brazil. The results demonstrate that the quality control of similar drugs must be improved as were the ones that presented quality deviations