Estabilidade química, físico-química e microbiológica de polpas de acerola pasteurizadas e não-pasteurizadas de cultivo orgânico.

O presente trabalho objetivou avaliar a estabilidade química, físico-química e microbiológica de polpas de acerola pasteurizadas e não-pasteurizadas, oriundas de cultivo orgânico e armazenadas sob congelamento (-18±2ºC) durante 360 dias. O armazenamento sob congelamento não ocasionou perdas significativas de qualidade das polpas de acerola. No entanto, o tratamento térmico influenciou negativamente nos conteúdos iniciais de alguns componentes, principalmente sólidos solúveis, açúcares solúveis totais e redutores, que apresentaram conteúdos inferiores no início do armazenamento para as polpas pasteurizadas. As polpas pasteurizadas e não-pasteurizadas apresentaram boa qualidade microbiológica do início ao final do armazenamento. Dentre as polpas estudadas, as polpas não-pasteurizadas apresentaram melhores características iniciais de cor. As polpas pasteurizadas garantiram melhores características microbiológicas no que concerne aos aspectos de segurança alimentar

Resultados da participação do Paraguai no estudo nutritionDay 2021

Each year, nutritionDay (nDay) provides de opportunity to analyze the intention to optimize nutritional and metabolic support and compare results with those obtained in the region and in the world. The aim of this study is to present the most relevant results of nDay in inpatient hospital wards and Intensive Care Units in 2021.El nutritionDay (nDay) ayuda a analizar cada año la intención de optimizar el soporte nutricional y metabólico, y comparar los resultados con los obtenidos en la región y en el mundo. El objetivo de este estudio es presentar los resultados más relevantes del nDay en las salas de internación de hospitales y unidades de cuidados intensivos (UCI) en 2021.O nutritionDay (nDay) ajuda a analisar a cada ano a intenção de otimizar o suporte nutricional e metabólico e comparar os resultados com os obtidos na região e no mundo. O objetivo deste estudo é apresentar os resultados mais relevantes do nDay nas unidades de internação hospitalar e unidades de terapia intensiva (UTI) em 2021

Effect of 1-octanethiol as an electrolyte additive on the performance of the iron-air battery electrodes

4 figuresIt has recently been established that 1-octanethiol in the electrolyte can allow iron electrodes to be discharged at higher rates. However, the effect of thiol additives on the air electrode has not yet been studied. The effect of solvated thiols on the surface positive electrode reaction is of prime importance if these are to be used in an iron-air battery. This work shows that the air-electrode catalyst is poisoned by the presence of octanethiol, with the oxygen reduction overpotential at the air electrode increasing with time of exposure to the solution and increased 1-octanethiol concentration in the range 0–0.1 mol dm−3. Post-mortem XPS analyses were performed over the used air electrodes suggesting the adsorption of sulphur species over the catalyst surface, reducing its performance. Therefore, although sulphur-based additives may be suitable for nickel-iron batteries, they are not recommended for iron-air batteries except in concentrations well below 10 × 10−3 mol dm−3.This work was enabled by an EU grant FP7 (NECOBAUT grant agreement no. 314159). H.A.F-R. acknowledges financial support from CONACYT, Mexico. CNR-ITAE authors acknowledge funding from the “Accordo di Programma CNR-MiSE, Gruppo tematico Sistema Elettrico Nazionale – Progetto: Sistemi elettrochimici per l’accumulo di energia”. C.A. thanks the Short-Term Mobility project of CNR and for her Juan de la Cierva contract (FJCI-2015-25560). The authors also acknowledge financial support given by Aragon Government to the Fuel Conversion Group (T06_17R).Peer reviewe

Effect of C-rate on the operation of iron-carbon-sulfur composites anodes for Fe-air batteries

Póster presentado en el MABIC 2019, Metal-advanced Batteries International Congress, 6 y 7 de noviembre 2019, Pamplona.Peer reviewe

Iron electrodes based on sulfur-modified iron oxides with enhanced stability for iron-air batteries

7 figures.-- Supporting information available.Iron–air systems are a very promising technology with the potential to become one of the cheapest and safest energy storage solutions of the future. However, iron anodes still face some challenges like passivation, resulting in loss of capacity, due to the formation of nonconductive species during cycling as well as the hydrogen evolution reaction, a parasitic reaction interfering with the charging of the electrode. In the present work these two issues are addressed: Sulfur-modified mesoporous iron oxides are obtained and used as hot-pressed negative electrodes for alkaline iron–air batteries. Iron electrodes present average capacity values between 400 and 500 mA h g Fe–1 for ∼100 h of operation, the S-modified iron oxides being the most stable ones. An exponential deactivation model fitting the discharge capacity of the different electrodes compared to the number of cycles was proposed. According to the model, the best of the electrodes loses less than 0.5% of its capacity per cycle. Furthermore, doubling the charge and discharge rates allows increasing both the discharge capacity and the Coulumbic efficiency, though at the expense of stability. This manuscript proves that the proper distribution of sulfur on the surface of the iron oxide is fundamental to suppress the HER and passivation, enhancing the stability of the electrode. These properties were further corroborated in long test-runs which comprised more than 400 h of charging and discharging.The authors acknowledge the financial support from the Aragón Government to the Fuel Conversion Group (Grant T06-20R). C.A. also acknowledges MICINN for her Juan de la Cierva Contract IJCI-2017-32354. N.V. acknowledges the Aragón Government for his predoctoral contract and Ibercaja and Erasmus programs for the funding of his research stay in the University of Southampton in July 2018.Peer reviewe

Investigation of the properties influencing the deactivation of iron electrodes in iron-air batteries

Iron-air batteries hold the potential to be a key technology for energy storage, thanks to their energy density, low cost, safety and abundance of their materials. In order to scale the technology up and optimize the cell formulations, it is key to obtain a clear understanding of how the physical-chemical properties of the electrode influence their electrochemical behaviour, in particular, the capacity loss. In this work, we propose for the first time mathematical correlations between textural and crystallographic properties of iron electrodes and their electrochemical stability. By adjusting synthesis parameters, we were able to tune pore size and volume, surface area and crystal size of iron oxides, and found that stability is highly correlated to both surface area and pore size. Large surface area and small average pore size provide electrodes with enhanced stability. We hypothesize that the cause for deactivation is the passivation of the electrodes ascribed to the formation of a non-conductive, non-reactive iron (II) hydroxide layer during discharge, which then cannot be reduced to iron again. We validate this hypothesis with electrochemical impedance spectroscopy studies, which show that, in the more stable electrodes, the charge transfer resistance in the Fe(OH)2 to Fe reduction does not significantly change after cycling, contrary to the behaviour of the less stable electrodes, corroborating our hypothesis. Furthermore, the electrode with the best properties was cycled 100 times, retaining almost 75% of its initial capacity at the end of the 100 cycles. These results are highly relevant for the future design and operation of iron-air batteries

Electrodos avanzados para baterías de nueva generación hierro-aire

1 Figura.-- Presentado en las XXXVI Jornadas Nacionales de Ingeniería Química, JNIQ 2019, Zaragoza, 4-6 Sep. 2019.Las energías renovables son actualmente el modo más sostenible y limpio de producción de energía. Sin embargo, su naturaleza intermitente es uno de los factores limitantes para su mayor expansión e implementación en las redes de suministro eléctrico. Las baterías recargables son óptimas candidatas para el almacenamiento de dicha energía debido a su elevada eficiencia, su escalabilidad y flexibilidad1, siendo las baterías de flujo redox o las de plomo-ácido las más empleadas, junto con las baterías de ion litio, utilizadas principalmente en vehículos y dispositivos eléctricos. En las últimas décadas, la investigación en dispositivos de almacenamiento de energía se centra en desarrollar baterías de nueva generación con mayor potencia, mayor densidad energética y cuyos materiales sean seguros, económicos y abundantes. Las baterías metal-aire (MABs) pertenecen a esta nueva generación de baterías: con densidades de energía teóricas entre 1000 y 11000 Wh/kg (frente a los 250 Wh/kg aprox. de las baterías de ion litio), menores costes, y el uso de materiales abundantes, reciclables y sin los problemas de seguridad del litio 2. Las MABs generan electricidad a través de una reacción redox entre el metal (electrodo negativo) y el oxígeno del aire (que reacciona en el electrodo positivo), que, al no estar directamente almacenado en la celda, hace estas baterías mucho más ligeras. Existen diversos tipos de MABs, según sea el metal que empleen en el electrodo negativo: Zn, Al, Mg, Li, Na o Fe. De entre todos ellos, el sistema Fe-aire es uno de los más atractivos. El Fe es el cuarto elemento más abundante de la corteza terrestre, se produce en todo el mundo, su producción posee la menor huella de carbono de todos los metales, y, además, es fácilmente reciclable. Las baterías hierro-aire (FAB), con un voltaje de celda de 1,28 V, presentan hasta 764 Wh/kg de densidad de energía, así como la reversibilidad de la electroquímica del hierro, la simplicidad del diseño, y una gran durabilidad (resisten más de 1000 ciclos)3. No obstante, las FABs presentan una serie de retos que todavía requieren mayor investigación y desarrollo. El electrodo positivo debe ser un catalizador bifuncional, es decir, capaz de desarrollar la reducción de oxígeno (descarga) y la evolución de oxígeno (carga), ésta última con el problema añadido de su elevado potencial, lo que compromete la estabilidad de la mayoría de catalizadores, generalmente basados en materiales carbonosos4. Por otro lado, el electrodo negativo presenta una baja eficiencia culómbica de los ciclos carga-descarga (debido a la reacción parásita de evolución de hidrógeno, HER) y la pasivación del hierro (debida a la formación de productos de la descarga como Fe(OH)2 o FeOOH que no son conductores)3. Este trabajo tiene como objetivo investigar y desarrollar nanomateriales avanzados para la fabricación de electrodos negativos para baterías hierro-aire, compuestos de Fe, S y C. La idea principal es desarrollar composites basados en hierro de fácil obtención, dopados con azufre (para suprimir los problemas derivados de la HER) y soportados en materiales porosos y conductores, que eviten la pasivación del electrodo.Los autores agradecen la financiación de la Unión Europea, a través del proyecto NECOBAUT (New Concept of Metal-Air Battery for Automotive Application based on Advanced Nanomaterials). Grant agreement no: 314159. C. Alegre agradece al CNR-ITAE la beca Short-Term- Mobility para la Universidad de Southampton. Los autores agradecen al Gobierno de Aragón la financiación aportada al Grupo de Investigación Conversión de Combustibles (T06_17R). N. Villanueva agradece al Gobierno de Aragón la financiación de su contrato pre-doctoral.Peer reviewe