Stainless steel foam increases the current produced by microbial bioanodes in bioelectrochemical systems

Stainless steel is gaining increasing interest as an anodic material in bioelectrochemical systems and beginning to challenge the more conventional carbon-based materials. Here, microbial bioanodes designed under optimal conditions on carbon cloths gave high current densities, 33.5 + 4.5 A m−2 at −0.2 V/SCE, which were largely outstripped by the current densities of 60 to 80 A m−2 at the same potential and more than 100 A m−2 at 0.0 V/SCE provided by using stainless steel foams

Lowering the applied potential during successive scratching/re-inoculation improves the performance of microbial anodes for microbial fuel cells

Microbial anodes were formed under polarisation at -0.2 V/SCE on smooth graphite plate electrodes with paper mill effluents. Primary, secondary and tertiary biofilms were formed by a successive scratching and re-inoculation procedure. The secondary and tertiary biofilms formed while decreasing the polarisation potential allowed the anodes to provide current density of 6 A/m² at -0.4 V/SCE. In contrast, applying -0.4 V/SCE initially to form the primary biofilms did not lead to the production of current. Consequently, the scratching/re-inoculation procedure combined with progressive lowering of the applied potential revealed an efficient new procedure that gave efficient microbial anodes able to work at low potential. The observed progressive pH drift to alkaline values above 9 explained the open circuit potentials as low as -0.6 V/SCE. The remarkable performance of the electrode at alkaline pH was attributed to the presence of Desulfuromonas acetexigens as the single dominant species in the tertiary microbial anodes

Lowering the applied potential during successive scratching/re-inoculation improves the performance of microbial anodes for microbial fuel cells

Microbial anodes were formed under polarisation at -0.2 V/SCE on smooth graphite plate electrodes with paper mill effluents. Primary, secondary and tertiary biofilms were formed by a successive scratching and re-inoculation procedure. The secondary and tertiary biofilms formed while decreasing the polarisation potential allowed the anodes to provide current density of 6 A/m² at -0.4 V/SCE. In contrast, applying -0.4 V/SCE initially to form the primary biofilms did not lead to the production of current. Consequently, the scratching/re-inoculation procedure combined with progressive lowering of the applied potential revealed an efficient new procedure that gave efficient microbial anodes able to work at low potential. The observed progressive pH drift to alkaline values above 9 explained the open circuit potentials as low as -0.6 V/SCE. The remarkable performance of the electrode at alkaline pH was attributed to the presence of Desulfuromonas acetexigens as the single dominant species in the tertiary microbial anodes

Application of the penalty coupling method for the analysis of blood vessels

Due to the significant health and economic impact of blood vessel diseases on modern society, its analysis is becoming of increasing importance for the medical sciences. The complexity of the vascular system, its dynamics and material characteristics all make it an ideal candidate for analysis through fluid structure interaction (FSI) simulations. FSI is a relatively new approach in numerical analysis and enables the multi-physical analysis of problems, yielding a higher accuracy of results than could be possible when using a single physics code to analyse the same category of problems. This paper introduces the concepts behind the Arbitrary Lagrangian Eulerian (ALE) formulation using the penalty coupling method. It moves on to present a validation case and compares it to available simulation results from the literature using a different FSI method. Results were found to correspond well to the comparison case as well as basic theory

Experimental and theoretical characterization of microbial bioanodes formed in pulp and paper mill effluent in electrochemically controlled conditions

Microbial bioanodes were formed in pulp and paper effluent on graphite plate electrodes under constant polarization at -0.3 V/SCE, without any addition of nutriment or substrate. The bioanodes were characterized in 3-electrode set-ups, in continuous mode, with hydraulic retention times from 6 to 48 h and inlet COD from 500 to 5200 mg/L. Current densities around 4 A/m2 were obtained and voltammetry curves indicated that 6 A/m2 could be reached at +0.1 V/SCE. A theoretical model was designed, which allowed the effects of HRT and COD to be distinguished in the complex experimental data obtained with concomitant variations of the two parameters. COD removal due to the electrochemical process was proportional to the hydraulic retention time and obeyed a Michaelis–Menten law with respect to the COD of the outlet flow, with a Michaelis constant KCOD of 400 mg/L. An inhibition effect occurred above inlet COD of around 3000 mg/L

Sampling location of the inoculum is crucial in designing anodes for microbial fuel cells

A Kraft pulp mill effluent was used as the inoculum to form microbial bioanodes under controlled potential at +0.4 V/SCE. Samples were collected at the inlet and outlet of the aerated lagoon of the treatment line. The outlet sample allowed efficient bioanodes to be designed (5.1 A/m²), which included Geobacter and Desulfuromonas sp. in their microbial community. In contrast, the bioanodes formed with the inlet sample did not contain directly connecting anode-respiring bacteria and led to lower currents. It was necessary to reform this bioanode at lower applied potential (-0.2 V/SCE) to select more efficient electroactive species and increase the current density to 5 A/m²

Nutritional valuation of schoolchildren from three Ibero-American countries: A comparative analysis of the references proposed by International Obesity Task Force (IOTF) and World Health Organization (WHO)

Introducción: El índice de masa corporal (IMC) resulta un indicador útil para valorar la condición nutricional en la infancia y adolescencia. Si bien no existe consenso respecto a los valores o puntos de corte de IMC que deben utilizarse para la diagnosis del sobrepeso, la obesidad o la insuficiencia ponderal, las referencias propuestas por la Organización Mundial de la Salud (OMS) y la International Obesity Task Force (IOTF) son las más aceptadas. No obstante, existen discrepancias importantes en los resultados obtenidos en función de una u otra referencia. Objetivo: Analizar y comparar la condición nutricional de una muestra internacional a partir del IMC, mediante la aplicación simultánea de las referencias recomendadas por la IOTF y la OMS. Métodos: Se calculó el IMC de 1289 escolares de 10 a 13 años de México, Venezuela y España. A cada niño le fue atribuida una categoría nutricional (bajo peso, normopeso, sobrepeso y obesidad) utilizando el criterio de la IOTF (puntos de corte equivalentes a 18,5; 25 y 30 en adultos) y OMS (-1 DE: bajo peso + 1 DE: sobrepeso y +2 DE: obesidad). Las prevalencias de estado nutricional obtenidas por cada criterio fueron comparadas mediante la prueba de Chi-Cuadrado. Resultados: El porcentaje de escolares en cada una de las categorías nutricionales varió significativamente en función de la referencia empleada. La prevalencia de malnutrición por exceso o por defecto fue, en ambos sexos y en los tres países, superior al emplear los parámetros OMS. La referencia OMS evidenció un 10,9% menos de niños normonutridos y un 13,1% más de malnutridos que la IOTF. Discusión: Los resultados de esta investigación permiten inferir que la referencia propuesta por la OMS resulta ser más “preventiva” al momento de identificar individuos malnutridos. Se subraya la importancia de especificar los criterios empleados para la determinación del estado nutricional en los estudios de carácter epidemiológico, así como de contrastar las referencias empleadas para el diagnóstico. Conclusiones: Las referencias OMS para IMC sobrestiman la prevalencia de bajo peso, sobrepeso y obesidad en relación a los puntos de corte propuestos por el IOTF para el diagnóstico de la malnutrición.Introduction: Body Mass Index (BMI) is a useful tool for assessing nutritional status in childhood and adolescence. Although there is no consensus on BMI values or cutoffs to be used for the diagnosis of overweight, obesity and underweight references proposed by World Health Organization (WHO) and International Obesity Task Force (IOTF) are the most accepted. However, there are significant discrepancies in the results obtained in terms of either reference. Objective: To analyze and compare the nutritional status of an international sample from IMC, by simultaneous application of IOTF and WHO recommended references. Methods: 1289 schoolchildren’s BMI between 10 and 13 years of Mexico, Venezuela and Spain was estimated. Each child was assigned a nutritional category (underweight, normal weight, overweight and obese) using the IOTF criteria (points cut equivalent to 18,5, 25 and 30 in adults) and WHO (-1 SD: low weight +1 DE: overweight and +2 SD: obesity). The prevalence of nutritional status of each criterion was compared using the Chi-square test. Results: The percentage of students in each of the nutritional categories mottled significantly depending on the reference used. The prevalence of excess or defect malnutrition, in both sexes and in all three countries, was exceeded using the WHO parameters. WHO reference showed 10,9% less than well-nourished children and 13,1 % more malnourished than the IOTF. Discussion: The results of this research allow inferring that the reference proposed by WHO appears to be more “protecting” when identifying malnourished individuals. The importance of specifying the criteria for determination of nutritional status in epidemiologic studies, as well as to contrast the references used for diagnosis, is emphasized. Conclusions: The WHO BMI references overestimate the prevalence of underweight, overweight and obesity in relation to the cutoff points proposed by the IOTF for diagnosing malnutrition.Fil: Bergel Sanchís, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Cesani Rossi, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Cordero, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucuman. Instituto Superior de Estudios Sociales; ArgentinaFil: Navazo, Bárbara. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Departamento Científico de Antropología. Cátedra de Antropología Biológica Iv; ArgentinaFil: Olmedo, S.. Programa de Ecología Reproductiva del Gran Chaco Argentino. Formosa; ArgentinaFil: Quintero, F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Departamento Científico de Antropología. Cátedra de Antropología Biológica Iv; ArgentinaFil: Sardi, Marina Laura. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Departamento de Antropología; ArgentinaFil: Torres, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras; ArgentinaFil: Arechiga, J.. Universidad Nacional Autónoma de México; MéxicoFil: Méndez de Pérez, B. Universidad Nacional de Venezuela; VenezuelaFil: Marrodán, M. D.. Universidad Complutense de Madrid; Españ

Harvesting Electricity with Geobacter bremensis Isolated from Compost

Electrochemically active (EA) biofilms were formed on metallic dimensionally stable anode-type electrode (DSA), embedded in garden compost and polarized at +0.50 V/SCE. Analysis of 16S rRNA gene libraries revealed that biofilms were heavily enriched in Deltaproteobacteria in comparison to control biofilms formed on non-polarized electrodes, which were preferentially composed of Gammaproteobacteria and Firmicutes. Among Deltaproteobacteria, sequences affiliated with Pelobacter and Geobacter genera were identified. A bacterial consortium was cultivated, in which 25 isolates were identified as Geobacter bremensis. Pure cultures of 4 different G. bremensis isolates gave higher current densities (1400 mA/m2 on DSA, 2490 mA/m2 on graphite) than the original multi-species biofilms (in average 300 mA/m2 on DSA) and the G. bremensis DSM type strain (100–300 A/m2 on DSA; 2485 mA/m2 on graphite). FISH analysis confirmed that G. bremensis represented a minor fraction in the original EA biofilm, in which species related to Pelobacter genus were predominant. The Pelobacter type strain did not show EA capacity, which can explain the lower performance of the multi-species biofilms. These results stressed the great interest of extracting and culturing pure EA strains from wild EA biofilms to improve the current density provided by microbial anodes

How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross‐Laboratory Study

A cross‐laboratory study on microbial fuel cells (MFC) which involved different institutions around the world is presented. The study aims to assess the development of autochthone microbial pools enriched from domestic wastewater, cultivated in identical single‐chamber MFCs, operated in the same way, thereby approaching the idea of developing common standards for MFCs. The MFCs are inoculated with domestic wastewater in different geographic locations. The acclimation stage and, consequently, the startup time are longer or shorter depending on the inoculum, but all MFCs reach similar maximum power outputs (55±22 μW cm−2) and COD removal efficiencies (87±9 %), despite the diversity of the bacterial communities. It is inferred that the MFC performance starts when the syntrophic interaction of fermentative and electrogenic bacteria stabilizes under anaerobic conditions at the anode. The generated power is mostly limited by electrolytic conductivity, electrode overpotentials, and an unbalanced external resistance. The enriched microbial consortia, although composed of different bacterial groups, share similar functions both on the anode and the cathode of the different MFCs, resulting in similar electrochemical output