Increased power from a two-chamber microbial fuel cell with a low-pH air-cathode compartment

Pt-supported air-cathodes still need improvement if their application in MFC technology is to be sustainable. In this context, the efficiency of an air-cathode was studied with respect to the pH of the solution it was exposed to. Voltammetry showed that oxygen reduction was no longer limited by H+ availability for pH lower than 3.0. A new MFC was designed with a catholyte compartment setup between the anode compartment and the air-cathode. With a catholyte compartment at pH 1.0, the MFC provided up to 5 W/m2, i.e., 2.5-fold the power density obtained with the same anode and cathode in a single-chamber MFC working at pH 7.5. Current density exceeded 20 A/m2. The benefit of low-pH in the catholyte chamber largely counterbalanced the mass transfer hindrance due the membrane that separated the two compartments. The MFC kept 66% its performance during nine days of continuous operation

From microbial fuel cell (MFC) to microbial electrochemical snorkel (MES): maximizing chemical oxygen demand (COD) removal from wastewater

The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a “short-circuited” microbial fuel cell (MFC). The MES cannot provide current but it is optimized for wastewater treatment. An electrochemically active biofilm (EAB) was grown on graphite felt under constant polarization in an urban wastewater. Controlling the electrode potential and inoculating the bioreactor with a suspension of an established EAB improved the performance and the reproducibility of the anodes. Anodes, colonized by an EAB were tested for the chemical oxygen demand (COD) removal from urban wastewater using a variety of bio-electrochemical processes (microbial electrolysis, MFC, MES). The MES technology, as well as a short-circuited MFC, led to a COD removal 57% higher than a 1000 Ω-connected MFC, confirming the potential for wastewater treatment

Progressive growing of self-organized hierarchical representations for exploration

Designing agent that can autonomously discover and learn a diversity of structures and skills in unknown changing environments is key for lifelong machine learning. A central challenge is how to learn incrementally representations in order to progressively build a map of the discovered structures and re-use it to further explore. To address this challenge, we identify and target several key functionalities. First, we aim to build lasting representations and avoid catastrophic forgetting throughout the exploration process. Secondly we aim to learn a diversity of representations allowing to discover a "diversity of diversity" of structures (and associated skills) in complex high-dimensional environments. Thirdly, we target representations that can structure the agent discoveries in a coarse-to-fine manner. Finally, we target the reuse of such representations to drive exploration toward an "interesting" type of diversity, for instance leveraging human guidance. Current approaches in state representation learning rely generally on monolithic architectures which do not enable all these functionalities. Therefore, we present a novel technique to progressively construct a Hierarchy of Observation Latent Models for Exploration Stratification, called HOLMES. This technique couples the use of a dynamic modular model architecture for representation learning with intrinsically-motivated goal exploration processes (IMGEPs). The paper shows results in the domain of automated discovery of diverse self-organized patterns, considering as testbed the experimental framework from Reinke et al. (2019)

Local analysis of oxygen reduction catalysis by scanning vibrating electrode technique : a new approach to the study of biocorrosion

The scanning vibrating electrode technique (SVET)was employed to investigate oxygen reduction catalysis by the presence of enzyme in an aerobic medium. Heme protoporphyrin (hemin) was chosen as a model of the enzymes that are able to catalyze oxygen reduction. A strict experimental protocol was defined for preparing the graphite surface by deposition of hemin with a simple configuration mimicking the presence of enzyme on the samples. The same configuration was adapted to a stainless steel electrode. Different geometric arrangementswere investigated by SVET to approach the local conditions. The results demonstrated that hemin deposited on the electrode surface led to an increase in the cathodic current, which indicated a catalytic effect. Based on the SVET analysis, itwas demonstrated that hemin caused the appearance of galvanic cells on the material surface. The SVET proved able to locate active catalytic centres and therefore to foresee the contribution of the enzyme to the creation of galvanic cells, thus leading to localized corrosion. The application of SVET to the study of the interaction between biological molecules and material provides a newapproach for visualizing and understanding microbially influenced corrosion (MIC) in an aerobic medium

Development of nickel phosphorus coatings containing micro particles of talc phyllosilicates

The present work aims to characterized nickel phosphorus coatings co-deposited with talc particles on steel. The NiP-talc composite deposits were developed to serve as hard coatings with a lubricating effect at 600 C. This process, which is free of hexavalent chromium, could provide a reliable substitute for the electrodeposition of hard chromium coating used in industrial applications. Local responses to static and dynamic mechanical loading have been obtained by nano- and microhardness, microtensile and nanoscratch testing. The hardness and stiffness values slightly decrease when the amount of talc increases for untreated coatings. In contrast, a 420 C heat treatment leads to high hardness and Young’s modulus values due to crystallization. Moreover, a 600 C heat treatment lowers these values through overageing. A 420 C heat treatment greatly improves the adherence and the cohesion of the coatings containing talc

Envejeciendo saludablemente

Ninguna práctica extiende un certificado que acredite una buena salud a futuro, ni que asegure longevidad apacible. Sin embargo, las experiencias de movimiento- sobre todo de índole consciente-, seguramente aporten herramientas y recursos a cada individuo para conectarse buenamente con su realidad corporal en permanente cambio. Escuchar al cuerpo, aún en la vejez, descifrar sus mensajes, ponerlo en situación de observación y registro son las claves para acompañar el proceso que enfrentan los adultos mayores. Aprender a transcurrir viva y activamente acorde a los tiempos y quehaceres ante los que nos pone la vida y no frente a ella como un combate, sino en ella misma puede ser un desafío. Pero pensemos que aún mejor es descubrir esa oportunidad más de aprender a disfrutarla. Conectarse amorosamente consigo es la clave para de-construir caminos que conduzcan a rehacer y reconstruir ese cuerpo que somos, plenos de experiencia, ese cuerpo ético y no disciplinado que se espera desde lo social. El método de la Sensopercepcepción colaborará en restablecer el cuerpo que somos para que no esté en soledad sino verdaderamente cuidado y reconocido. Como especialistas debemos saber que la juventud no vuelve y jamás se deberían alentar falsas expectativas que están destinadas al fracaso y en muchos casos enmascaran la crueldad del desengañ