COVID-19 and its impact on the kidney and the nephrology community

COVID-19; NephrologyCOVID-19; NefrologiaCOVID-19; NefrologíaThis article is part of a supplement supported by Fresenius Medical Care without any influence on its content

Review of technologies for the rapid detection of chemical and biological contaminants in drinking water

In the event of potential intentional contamination of drinking water, the risk to public health must be minimised, requiring confirmation of contamination, and, if possible, identification of the contaminant. A crucial step is to determine in the shortest possible time the type of contaminant. This review, developed within the framework of guidance for the production of a Water Security Plan (Teixeira et al. 2019), aims to help water utilities, laboratories and other stakeholders improve their analytical capacities to identify unknown contaminants in drinking water. An insight on sampling procedures in emergency situations is followed by a proposed approach for the use of non-targeted technologies to determine both toxicity and ATP (Adenosine Triphosphate). Toxicity analysis quickly detects toxic chemical contaminants, while the measurement of the ATP is a first indicator of a contamination by microorganisms. The non-target technologies to determine toxicity and ATP in water that comply with the required characteristics for emergency response, i.e. quick, reliable, and easy to operate, are available now in the market, and could be adopted by most drinking water utilities and/or laboratories, in conjunction with the establishment of appropriate sampling capabilities. The subsequent step of contaminant identification requires the application of rapid analytical targeted technologies, such as immunological based methods, polymerase chain reaction (PCR) and sequencing technologies, as well as field analysis by gas chromatography (GC/MS). These targeted technologies are based on tests available on the market with the focus on rapidness and reliability of results. The commercially available analytical tools and methodologies that detect and identify a chemical or biological contaminant are reviewed through a detailed description of the equipment, including the technology, equipment prices, testing cost, expected time to obtain a result, reagents and respective shelf-time and manufacturers. Information is provided on proficiency tests for analysis of unknown contamination events in drinking water that ensure the external quality control of the analytical process. To assist utilities and laboratories in their consideration of targeted and non-targeted technologies, an approach for identifying water contaminants in emergency situations is proposed comprising a series of steps of analysis to be adapted by each water utility in line with its business goals and risk assessment. This review of analytical technologies aims at supporting water utilities, laboratories, health authorities and other stakeholders in planning responses to emergency events in drinking water quality, in particular to enhance the rapid identification of unknown water contaminants. Consideration of these technologies, within the framework of a Water Security Plan, along with appropriate planning and protection measures, will enable water utilities to better respond to unexpected drinking water contaminations.JRC.E.2-Technology Innovation in Securit

An analysis of repair practices in L2 Spanish listening comprehension materials with implications for teaching interactional competence

Listening materials are commonly developed so students show their understanding of a specific oral discourse. Oral interactions provided in textbooks are resources in which different interactional practices are involved, repair practices being one of these. This article seeks to explore, first, the types of repair practices found in Spanish as a Foreign Language (SFL) textbook listening interactions and, second, the relationship between repairs and other characteristics of the interactions to determine to what extent SFL listening practices are appropriate resources to show examples of repair work and to develop the students' Interactional Competence. Following a Conversation Analysis perspective, 109 repairs in 504 SFL audiotaped listening materials from 18 textbooks are analysed. The results show that repairs are not a common practice in listening materials, other-initiated self-repairs being the most common type of repair work. A disparity is also observed in establishing repair through listening materials depending on the textbook. Some of them include self repairs together with other interactional features, such as overlapped turns, articulated pauses or response tokens, while other textbooks rarely present any repair work. These findings improve our understanding of the degree of authenticity of listening materials, which might help students develop their interactional competence

Distributed parameter model simulation tool for PEM fuel cells

In this work, a simulation tool for proton exchange membrane fuel cells (PEMFC) has been developed, based on a distributed parameter model. The tool is designed to perform studies of time and space variations in the direction of the gas channels. Results for steady-state and dynamic simulations for a single cell of one channel are presented and analyzed. Considered variables are concentrations of reactants, pressures, temperatures, humidification, membrane water content, current density, among others that have significant effects on the performance and durability of PEMFC

Distributed parameter model-based control of water activity and concentration of reactants in a polymer electrolyte membrane fuel cell

Water management is still a key challenge for optimal performance and durability of polymer electrolyte membrane (PEM) fuel cells. Water levels along the channel in a PEM fuel cell present important spatial variations that should be taken into account to avoid both local flooding and local drying. In this work, a decentralised model predictive control scheme is designed to maintain the water activity on both anode and cathode sides of the PEM at appropriate levels. The proposed strategy tackles the accumulation of liquid water on the surface of the catalyst layers, and the possibility of local drying, by controlling observed water activity spatial profiles. Classic PEM fuel cell issues like reactant starvation are also considered. High control performance is achieved. The strategy is applied to a validated distributed parameter PEM fuel cell model. Results show increased cell power density in comparison to non-spatial control strategies

Distributed parameter model-based control of water activity and concentration of reactants in a polymer electrolyte membrane fuel cell

Water management is still a key challenge for optimal performance and durability of polymer electrolyte membrane (PEM) fuel cells. Water levels along the channel in a PEM fuel cell present important spatial variations that should be taken into account to avoid both local flooding and local drying. In this work, a decentralised model predictive control scheme is designed to maintain the water activity on both anode and cathode sides of the PEM at appropriate levels. The proposed strategy tackles the accumulation of liquid water on the surface of the catalyst layers, and the possibility of local drying, by controlling observed water activity spatial profiles. Classic PEM fuel cell issues like reactant starvation are also considered. High control performance is achieved. The strategy is applied to a validated distributed parameter PEM fuel cell model. Results show increased cell power density in comparison to non-spatial control strategies

Analysis of conventionally controlled PEMFC based on a distributed parameter model

Presentado al IV Iberian Symposium on Hydrogen, Fuel Cells and Advanced Batteries celebrado en Estoril (Portugal) del 26 al 28 de junio de 2013.The proton exchange membrane fuel cells (PEMFC) have been incorporated to a wide range of portable, stationary and automotive applications. However, PEMFC are still not accepted as a practical power generator. The key challenge is to reduce the cost and achieve a high performance and long life of the cells. Variations in the concentrations of reactants, as well as temperature, have significant effects on the performance and durability of PEMFC. All these variables exhibit spatial dependence along the channel, which needs to be taken into account in order to progress towards a PEMFC operation that is efficient and mitigates degradation. To this end, a controlled PEM fuel cell study is done through a distributed parameter simulation model. A conventional stoichiometry control objective is considered in order to analyze the behavior of spatial profiles of some important variables and, therefore, point out the importance of considering distributed parameter models in control design.Peer Reviewe

Distributed parameter model simulation tool for PEM fuel cells

En este trabajo se ha desarrollado una herramienta de simulación para pilas de combustible tipo PEM, basada en un modelo de parámetros distribuidos. La herramienta está diseñada para realizar estudios de variaciones espaciales y temporales a lo largo de los canales de alimentación de reactantes. El trabajo muestra y analiza los resultados de simulación de una monocelda monocanal. Las variables estudiadas son las concentraciones de los reactantes, presiones, temperaturas, humidificación, contenido de agua de la membrana, corriente, entre otras que influyen significativamente sobre el rendimiento y durabilidad de las pilas PEM.Peer ReviewedPostprint (published version

1,4-Benzodiazepines and New Derivatives: Description, Analysis, and Organic Synthesis

Benzodiazepines are widely used drugs for several indications. This study provides, on the other hand, a global vision of the family starting for their fortuitous discovery, the synthesis of their derivatives, their mechanism of action widely known nowadays, the actual classification according to the chemical structure and pharmacokinetic properties, and their uses and indications, the traditional and the new ones. On the other hand,the study is focused in the mainly problems of benzodiazepines, depedence, and tolerance, many times led by a misuse of the patient, wrong prescriptions, or extended treatments. A withdrawal program is proposed that includes the important factors or criteria to success, with a slow and gradual reduction of these drugs, avoiding relapse or severe adverse effects. New lines of research related to benzodiazepines are taken into account, which not only include the new therapeutic uses but also the adverse effects in short and long term. They are also analyzed the new discoveries concerning the nonbenzodiazepine drugs due to the close relation they have with benzodiazepines

Distributed parameter model simulation tool for PEM fuel cells

In this work, a simulation tool for proton exchange membrane fuel cells (PEMFC) has been developed, based on a distributed parameter model. The tool is designed to perform studies of time and space variations in the direction of the gas channels. Results for steady-state and dynamic simulations for a single cell of one channel are presented and analyzed. Considered variables are concentrations of reactants, pressures, temperatures, humidification, membrane water content, current density, among others that have significant effects on the performance and durability of PEMFC. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Peer ReviewedPostprint (published version