Study of the influence of phosphoric acid in steel anaerobic corrosion via the hydrogen evolution reaction.

Although it is well known that the phosphate species are quiet electrochemically inert when considering their calculated redox potential, few studies since the end of 80’s reported electrochemical phenomenon observed in the reduction domain which were linked to the presence of phosphate species. Some authors proposed that phosphate ions and weak acids in general catalysed the electrochemical reduction of water [1-3] following the kind of reactions written above: Electrochemical reactions H2PO4- + e- Had + HPO42- (1) Had + H2PO4- + e- H2 + HPO42- (2) Acido-basic equilibrium H2PO4- + OH-- H2O + HPO42- (3) Combining the reactions, the reduction of water was obtained 2 H2O + 2e- H2 + 2OH- (4) Marinovic and Despic [1] assumed that the hydrogen evolution was more likely to occur from species other than water, since the bond between the hydrogen atom and the rest of the molecule is weaker in weak acid compared with the hydrogen-oxygen bond in a water molecule. This was shown on silver electrodes [2] and also on platinum ones [1]. In a previous work [3], we showed that phosphate ions exhibited the same electrochemical behaviour on stainless steel. A theoretical model was proposed according to the experimental data the model showed that a significant quantity of molecular hydrogen was produced by the mechanism presented above. In the present paper, the influence of phosphoric acid on hydrogen evolution reaction has been studied by voltammetry on platinum and stainless steel rotating disc electrodes. A linear correlation between acid concentration and the absolute value of the current at certain reduction potential has been verified. The effect of the pH value of the solution in the obtained current has demonstrated to be strongly related to the dissociation state of the acid. In a second part, as the hydrogen evolution reaction is the principal cathodic reaction of metal corrosion in anaerobic aqueous environments, the role that weak acids can play in this process was studied. Corrosion experiments on carbon steel were carried out in phosphoric acid solution under anaerobic conditions. The influence of hydrogen in the solution was also studied. In the absence of oxygen, a substantial increase of corrosion rate was found when carbon steel samples were submerged in low phosphoric acid concentration solution compared to that obtained in distilled water

Induced pluripotent stem cells, a giant leap for mankind therapeutic applications

Induced pluripotent stem cells (iPSC) technology has propelled the field of stem cells biology, providing new cells to explore the molecular mechanisms of pluripotency, cancer biology and aging. A major advantage of human iPSC, compared to the pluripotent embryonic stem cells, is that they can be generated from virtually any embryonic or adult somatic cell type without destruction of human blastocysts. In addition, iPSC can be generated from somatic cells harvested from normal individuals or patients, and used as a cellular tool to unravel mechanisms of human development and to model diseases in a manner not possible before. Besides these fundamental aspects of human biology and physiology that are revealed using iPSC or iPSC-derived cells, these cells hold an immense potential for cell-based therapies, and for the discovery of new or personalized pharmacological treatments for many disorders. Here, we review some of the current challenges and concerns about iPSC technology. We introduce the potential held by iPSC for research and development of novel health-related applications. We briefly present the efforts made by the scientific and clinical communities to create the necessary guidelines and regulations to achieve the highest quality standards in the procedures for iPSC generation, characterization and long-term preservation. Finally, we present some of the audacious and pioneer clinical trials in progress with iPSC-derived cells.info:eu-repo/semantics/publishedVersio

Hydrogen production by electrolysis of a phosphate solution on a stainless steel cathode

The catalytic properties of phosphate species, already shown on the reduction reaction in anaerobic corrosion of steels, are exploited here for hydrogen production. Phosphate species work as a homogeneous catalyst that enhances the cathodic current at mild pH values. A voltammetric study of the hydrogen evolution reaction is performed using phosphate solutions at different concentrations on 316L stainless steel and platinum rotating disk electrodes. Then, hydrogen is produced in an electrolytic cell using a phosphate solution as the catholyte. Results show that 316L stainless steel electrodes have a stable behaviour as cathodes in the electrolysis of phosphate solutions. Phosphate (1 M,pH 4.0/5.0) as the catholyte can equal the performance of a KOH 25%w solution with the advantage of working at mild pH values. The use of phosphate and other weak acids as catalysts of the hydrogen evolution reaction could be a promising technology in the development of electrolysis units that work at mild pH values with low-cost electrodes and construction materials

Study on the relationship of producers of audiovisual content with their audiences: Youtube Brazil

Este artículo, busca aportar al área de las ciencias de la comunicación, conocimiento sobre un elemento de gran relevancia para las actividades de relaciones públicas en las redes sociales de contenido audiovisual. Esta investigación se centra en indagar y analizar el nivel de interacción de los productores de vídeos con su audiencia, específicamente en Youtube Brasil, el cual es el mayor difusor de contenidos audiovisuales a la fecha en ese país. Gestionar la relación con el público es, de hecho, parte de las relaciones públicas, pero cuando se trata de contenidos audiovisuales, la mayoría de las instituciones no se dan cuenta de la importancia de estas herramientas de interacción proporcionadas por Youtube. Este artículo muestra la importancia de utilizar estas herramientas para las personas y las instituciones que cuentan con un canal en esta red social. Con apoyo del enfoque cuantitativo, el estudio descriptivo, se analizará la información recopilada gracias a la observación. Para pruebas de lo mencionado, se muestra en este artículo datos recogidos, estadísticas y el análisis profundo de 100 vídeos de Youtube Brasil divididos en categorías populares desde el surgimiento de la red en agosto de 2013

Animals’ Health Control Efficiency in Northwest Portugal: A Two-stage DEA Approach

A two-stage approach is employed to analyze the efficiency of cooperatives responsible for ruminants’ disease control (OPP) at the farm level in Northwest Portugal. In the first stage, Data Envelopment Analysis (DEA) is used to estimate and decompose input-based overall inefficiency for each OPP. The input-based inefficiency measures are generated using the directional input distance function. In the second stage, the inefficiency estimates are regressed on environmental and organizational factors in order to explain efficiency differentials. Despite substantial environmental differences, the empirical results indicate that most cooperatives can reduce costs by improving scale efficiency and pure technical efficiency.input directional distance function, bootstrapping, economic efficiency, animal health services., Agricultural and Food Policy,

A Survey of Adaptive Resonance Theory Neural Network Models for Engineering Applications

This survey samples from the ever-growing family of adaptive resonance theory (ART) neural network models used to perform the three primary machine learning modalities, namely, unsupervised, supervised and reinforcement learning. It comprises a representative list from classic to modern ART models, thereby painting a general picture of the architectures developed by researchers over the past 30 years. The learning dynamics of these ART models are briefly described, and their distinctive characteristics such as code representation, long-term memory and corresponding geometric interpretation are discussed. Useful engineering properties of ART (speed, configurability, explainability, parallelization and hardware implementation) are examined along with current challenges. Finally, a compilation of online software libraries is provided. It is expected that this overview will be helpful to new and seasoned ART researchers