Evaluación de la corrosión de una aleación Pb-Ca-Sn por medio de técnicas electroquímicas

Evaluation of corrosion of Pb-Ca-Sn alloy by electrochemical techniques Avaliação da corrosão na liga Pb-Ca-Sn através de técnicas eletroquímicas   Resumen En el presente trabajo, se evaluó la influencia del aumento de la temperatura en la velocidad de corrosión de la aleación Pb-Ca-Sn, componente primario de la rejilla negativa de una batería de arranque de automóvil, mediante técnicas electroquímicas: RPL, curvas potenciodinámicas, Tafel y EIS. Mediante microscopia óptica, SEM-EDS y DRX, se caracterizaron los compuestos formados sobre las rejillas durante los ensayos. La capa pasiva formada sobre las rejillas empleadas como cátodo y ánodo en baterías de plomo-ácido, permite el anclaje en la interfase rejilla-PAM (Material Activo Positivo) o NAM (Material Activo Negativo). Un mal proceso de formación de esta capa ocasiona el desprendimiento del PAM/NAM, conduciendo a fallas prematuras. La temperatura influye directamente sobre la cinética de degradación y la termodinámica de las reacciones redox que tienen lugar en el sistema rejilla-PAM/ NAM. Un incremento en la temperatura produce variaciones en la composición química, favoreciendo la formación de mezclas de óxidos y sulfatos en la interfase rejilla-PAM/NAM, cuyo volumen y estructura porosa la hace susceptible a fallas por esfuerzos triaxiales sobre la interfase, produciendo grietas y el desprendimiento del PAM o NAM y disminuyendo el tiempo de vida útil de la batería. Se encontró que las aleaciones Pb-Ca-Sn en solución 0,5M de H2SO4 forman un sistema multicapa comprobándose con base en los resultados obtenidos de EIS y SEM, con los cuales se detectó una capa compacta de PbO2 y una capa porosa de PbSO4. Al incrementar la temperatura se encontró una capa más porosa de PbSO4, lo cual implica una mayor cinética de corrosión de la aleación Pb-Ca-Sn. Palabras clave: batería plomo-ácido, material activo negativo, corrosión, técnicas electroquímicas.   Abstract In this paper, the influence of increasing temperature on the corrosion rate of Pb-Ca-Sn alloy, the primary component of the negative grid of a starter battery car, was evaluated by electrochemical techniques: RPL, potentiodynamic curves, Tafel and EIS. By optical microscopy, SEM -EDS and XRD, the compounds formed on the grids were characterized during testing. The passive layer formed on the grids used as cathode and anode in lead-acid batteries allows the anchor in grid-PAM interface (Positive Active Material) or NAM (Negative Active Material). A bad process of to form this layer produces the detachment of PAM/NAM, leading to premature failure. The temperature directly affects the kinetics and thermodynamics degradation of the redox reactions taking place in the system grid-PAM/NAM. An increase in temperature causes variations in the chemical composition, favoring the formation of oxides and sulphates mixtures in grid-PAM/NAM interface, its volume and porous structure make it susceptible to failure by tri-axial stress on the interface, producing cracks and detachment of PAM or NAM and reducing the lifetime of the battery. It was found that the Pb-Ca-Sn alloys in 0.5M H2SO4 solution form a multilayer system, verified by the results of EIS and SEM, in which a compact layer of PbO2 and porous layer by PbSO4 . Porous layer of PbSO4 was obtained, when the temperature was increased implying greater corrosion kinetics ofPb-Ca-Sn alloy were detected. Keywords:lead-acid battery, negative active material, corrosion, electrochemical techniques.   Resumo Neste trabalho, a influência do aumento da temperatura sobre a taxa de corrosão da liga de Pb-Ca-Sn, o principal componente da grade negativa da bateria de arranque de um carro, foi avaliada por técnicas eletroquímicas: RPL, curvas potenciodinâmica, Tafel e EIS. Por microscopia óptica, SEM- EDS e XRD, os compostos formados nas grades foram caracterizados durante o teste. A camada passiva formada nas grades usadas como cátodo e o ânodo em baterias de chumbo-ácido, permite a âncora na interface de rede-PAM (Material Positivo Ativo) ou NAM (negativo material ativo). Um mau processo de formar esta camada leva ao desenvolvimento de PAM/NAM,conduzindo a falhas prematuras. A temperatura afeta diretamente a cinética de degradação e termodinâmica das reações redox que ocorrem no grade- PAM/NAM sistema. Um aumento da temperatura faz com que as variações na composição química, favorecendo a formação de misturas de óxidos e sulfatos na interface grade-PAM/NAM, o volume e estrutura porosa tornam susceptíveis de falha por stress triaxial na interface, produzindo fissuras e desprendimento do PAM ou NAM e reduzindo o tempo de vida da bateria. Verificou-se que as ligas de Pb-Ca-Sn em solução 0,5M de H2SO4 formar um sistema de múltiplas camadas , a verificação com base nos resultados da EIA e SEM , com as quais foi detectada uma camada compacta de PbO2 e camada porosa PbSO4 . Ao aumentar a temperatura de uma camada porosa de PbSO4 foi encontrado, o que implica maiores cinética de corrosão de liga de Pb-Ca-Sn . Palavras-chave:bateria de chumbo-ácido, material ativo negativo, corrosão, técnicas eletroquímicas.    Estupiñán Duran HA, Peña Ballesteros DY, Quijano EA, Peñate RA. Evaluación de la corrosión de una aleación Pb-Ca-Sn por medio de técnicas electroquímicas. rev.ion. 2014;27(1):71-80

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry

Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase

Evaluación de la corrosión de una aleación Pb-Ca-Sn por medio de técnicas electroquímicas

Evaluation of corrosion of Pb-Ca-Sn alloy by electrochemical techniques Avaliação da corrosão na liga Pb-Ca-Sn através de técnicas eletroquímicas   Resumen En el presente trabajo, se evaluó la influencia del aumento de la temperatura en la velocidad de corrosión de la aleación Pb-Ca-Sn, componente primario de la rejilla negativa de una batería de arranque de automóvil, mediante técnicas electroquímicas: RPL, curvas potenciodinámicas, Tafel y EIS. Mediante microscopia óptica, SEM-EDS y DRX, se caracterizaron los compuestos formados sobre las rejillas durante los ensayos. La capa pasiva formada sobre las rejillas empleadas como cátodo y ánodo en baterías de plomo-ácido, permite el anclaje en la interfase rejilla-PAM (Material Activo Positivo) o NAM (Material Activo Negativo). Un mal proceso de formación de esta capa ocasiona el desprendimiento del PAM/NAM, conduciendo a fallas prematuras. La temperatura influye directamente sobre la cinética de degradación y la termodinámica de las reacciones redox que tienen lugar en el sistema rejilla-PAM/ NAM. Un incremento en la temperatura produce variaciones en la composición química, favoreciendo la formación de mezclas de óxidos y sulfatos en la interfase rejilla-PAM/NAM, cuyo volumen y estructura porosa la hace susceptible a fallas por esfuerzos triaxiales sobre la interfase, produciendo grietas y el desprendimiento del PAM o NAM y disminuyendo el tiempo de vida útil de la batería. Se encontró que las aleaciones Pb-Ca-Sn en solución 0,5M de H2SO4 forman un sistema multicapa comprobándose con base en los resultados obtenidos de EIS y SEM, con los cuales se detectó una capa compacta de PbO2 y una capa porosa de PbSO4. Al incrementar la temperatura se encontró una capa más porosa de PbSO4, lo cual implica una mayor cinética de corrosión de la aleación Pb-Ca-Sn. Palabras clave: batería plomo-ácido, material activo negativo, corrosión, técnicas electroquímicas.   Abstract In this paper, the influence of increasing temperature on the corrosion rate of Pb-Ca-Sn alloy, the primary component of the negative grid of a starter battery car, was evaluated by electrochemical techniques: RPL, potentiodynamic curves, Tafel and EIS. By optical microscopy, SEM -EDS and XRD, the compounds formed on the grids were characterized during testing. The passive layer formed on the grids used as cathode and anode in lead-acid batteries allows the anchor in grid-PAM interface (Positive Active Material) or NAM (Negative Active Material). A bad process of to form this layer produces the detachment of PAM/NAM, leading to premature failure. The temperature directly affects the kinetics and thermodynamics degradation of the redox reactions taking place in the system grid-PAM/NAM. An increase in temperature causes variations in the chemical composition, favoring the formation of oxides and sulphates mixtures in grid-PAM/NAM interface, its volume and porous structure make it susceptible to failure by tri-axial stress on the interface, producing cracks and detachment of PAM or NAM and reducing the lifetime of the battery. It was found that the Pb-Ca-Sn alloys in 0.5M H2SO4 solution form a multilayer system, verified by the results of EIS and SEM, in which a compact layer of PbO2 and porous layer by PbSO4 . Porous layer of PbSO4 was obtained, when the temperature was increased implying greater corrosion kinetics ofPb-Ca-Sn alloy were detected. Keywords:lead-acid battery, negative active material, corrosion, electrochemical techniques.   Resumo Neste trabalho, a influência do aumento da temperatura sobre a taxa de corrosão da liga de Pb-Ca-Sn, o principal componente da grade negativa da bateria de arranque de um carro, foi avaliada por técnicas eletroquímicas: RPL, curvas potenciodinâmica, Tafel e EIS. Por microscopia óptica, SEM- EDS e XRD, os compostos formados nas grades foram caracterizados durante o teste. A camada passiva formada nas grades usadas como cátodo e o ânodo em baterias de chumbo-ácido, permite a âncora na interface de rede-PAM (Material Positivo Ativo) ou NAM (negativo material ativo). Um mau processo de formar esta camada leva ao desenvolvimento de PAM/NAM,conduzindo a falhas prematuras. A temperatura afeta diretamente a cinética de degradação e termodinâmica das reações redox que ocorrem no grade- PAM/NAM sistema. Um aumento da temperatura faz com que as variações na composição química, favorecendo a formação de misturas de óxidos e sulfatos na interface grade-PAM/NAM, o volume e estrutura porosa tornam susceptíveis de falha por stress triaxial na interface, produzindo fissuras e desprendimento do PAM ou NAM e reduzindo o tempo de vida da bateria. Verificou-se que as ligas de Pb-Ca-Sn em solução 0,5M de H2SO4 formar um sistema de múltiplas camadas , a verificação com base nos resultados da EIA e SEM , com as quais foi detectada uma camada compacta de PbO2 e camada porosa PbSO4 . Ao aumentar a temperatura de uma camada porosa de PbSO4 foi encontrado, o que implica maiores cinética de corrosão de liga de Pb-Ca-Sn . Palavras-chave:bateria de chumbo-ácido, material ativo negativo, corrosão, técnicas eletroquímicas.    Estupiñán Duran HA, Peña Ballesteros DY, Quijano EA, Peñate RA. Evaluación de la corrosión de una aleación Pb-Ca-Sn por medio de técnicas electroquímicas. rev.ion. 2014;27(1):71-80

Supplementary Material for: Does the New Staging System Proposed for Mycosis Fungoides and Sézary Syndrome Provide Reliable Agreement for T1 and T2 Disease?

<b><i>Background:</i></b> Patch or plaque stages in mycosis fungoides (MF) have different prognoses. The recent staging system proposed for MF discriminates between patches and plaques based upon clinical features. <b><i>Objective:</i></b> To estimate interdermatologist agreement on the morphological evaluation of MF lesions. <b><i>Methods:</i></b> Twenty-four patients with MF were enrolled. Two dermatologists evaluated every lesion face to face and independently with respect to the patch-plaque status. Cohen's κ was used to determine the rate of agreement. <b><i>Results:</i></b> Agreement was 67% with respect to the patch or plaque status [95% confidence interval (CI) = 49-85%; p < 0.001]. Current systemic treatment (56%; p = 0.01) was associated with lower agreement. Younger age at diagnosis [odds ratio (OR) 1.03 (95% CI 1.02-1.05)], younger age at enrolment [OR 1.03 (95% CI 1.02-1.04)] and time on systemic treatment [OR 1.02 (95% CI 1.01-1.04)] were independent risk factors for disagreement (p < 0.001). <b><i>Conclusion:</i></b> The new system for MF staging carries a significant risk of disagreement regarding patch and plaque subsets

Campos y perspectivas de la biotecnología: una estrategia para su introducción en el Istmo Centroamericano

134 páginasEste informe se propone analizar la introducción paulatina de la biotecnología a la agricultura, la ganadería, la silvicultura y la producción alimentaria, dentro de una estrategia global de desarrollo agrícola y agroindustrial para el istmo centroamericano. El objetivo es asegurar un crecimiento más endógeno y autosustentado de sus economías y una mayor autosuficiencia alimentaria en el marco de una inserción más dinámica en el mercado internacional