Development and testing of galvanic anodes for cathodic protection

Aquest treball resumeix els resultats obtinguts en un projecte de recerca dut a terme en el nostre laboratori i relacionat amb l'assaig electroquímic dels ànodes de sacrifici emprats en protecció catòdica, així com en el desenvolupament de nous ànodes d'alumini -Al- lliures d'indi -In- i de mercuri -Hg. Les aportacions més importants han estat fetes en els aspectes següents: 1. Mecanisme de corrosió durant els assaigs electroquímics. 1.1. Al. Assaig electroquímic d'ànodes de sacrifici de Al. 1.2. Mg. Mecanisme de dissolució dels ànodes de sacrifici de Mg durant l'assaig electroquímic. 1.3. Zn. L'impedància electroquímica com a eina d'assaig dels ànodes de sacrifici de Zn aplicats per projecció tèrmica sobre el formigó. 2. Augment de l'eficiència electroquímica dels ànodes de Mg mitjançant el tractament tèrmic i el control de la seva microestructura. 3. Disseny i desenvolupament de nous ànodes de Al sense In ni Hg. Aquests nous ànodes de Al-Zn-Mg-Li són proposats com una alternativa als actualment en ús. El sistema Al-Mg-Zn ha estat escollit a causa de la presència de precipitats en la matriu de l'alumini, que poden ser capaços de trencar la pel·lícula passiva, però mantenen una alta eficiència electroquímica.This paper summarizes the results obtained in the research project carried out in our laboratory related to the testing of sacrificial anodes used in cathodic protection (CP) systems and the development of new In/Hg-free aluminium-alloy anodes. The main contributions are in the following subjects: 1. Corrosion mechanism during electrochemical testing. 1.1. Al. Electrochemical testing of Al sacrificial anodes. 1.2. Mg. Dissolution mechanism of Mg sacrificial anodes under electrochemical testing. 1.3. Zn. EIS testing of thermal spray Zn anodes for concrete applications. 2. Improving the efficiency of Mg sacrificial anodes by microstructure control and heat treatments. 3. Design and development of new Al-alloy anodes In/Hg free. The evaluation of an Al-Zn-Mg-Li alloy as a potential candidate for Al-sacrificial anode was studied. The Al-Zn-Mg system was particularly selected due to the presence of precipitates in _-Al matrix which are capable of breaking down passive films whilst presenting good electrochemical efficiencies. The effect of Li additions on superficial activation of the anode by means of precipitation of AlLi type compounds was also examined

Fomento de las inteligencias múltiples en preescolar por medio de la estrategia del cuento

La presente investigación tiene la finalidad de presentar el diseño y la implementación de una estrategia educativa, a la cual se le llamó Cuento, con la cual se pretendió fomentar el desarrollo de las múltiples inteligencias en los niños. Esta investigación se basa en la Teoría de las Inteligencias Múltiples de Howard Gardner, la cual habla de cómo el conocimiento e identificación de los diferentes tipos de inteligencias (lingüística, lógica-matemática, corporal-cinética, musical, intrapersonal y naturalista) dan rutas alternativas para asegurar el éxito de la inteligencia en los alumnos y refuerzan las ventajas intelectuales para enfatizar los talentos de manera satisfactoria

Recovery of active pathogenesis-related enzymes from the apoplast of Musa acuminata infected by Mycosphaerella fijiensis

The fungus Mycosphaerella fijiensis causes black Sigatoka (BS) disease, a major pathogen in the banana industry worldwide. Numerous molecular and biochemical studies have been done for the M. fijiensis, Musa acuminata interaction, but this is the first study describing the zymographic behavior of β-1,3-glucanase, chitinase and protease in the apoplast and symplast of healthy, BS-infected but asymptomatic and BS diseased banana leaves. In BS-infected tissues, β-1,3-glucanase enzymatic activity was associated with two polypeptides with retention index (Ri) values of 0.43 and 0.56. These were more notable in the apoplast than in the symplast. Chitinase activity in BS-infected tissue in both the apoplast and symplast was mainly associated with a single polypeptide (Ri = 0.89). Both β-1,3-glucanase and chitinase activities were apparently more intense in BS-infected leaves than in healthy leaves. Protease activity was associated with two polypeptides (Ri = 0.04 and 0.14). In both the apoplast and symplast, the Ri 0.04 polypeptide increased in intensity with disease progression, whereas Ri 0.14 polypeptide intensity decreased. Overall protease activity intensity was higher in the symplast. Maximum symplast contamination of the apoplast was 2% as estimated by glucose 6-phosphate dehydrogenase activity, a biochemical marker for symplast. Accumulation of pathogenesis-related enzymatic activities in the apoplast of M. acuminata leaf tissue was caused by hostcontrolled enzyme downloading in response to M. fijiensis infection. Clear differences were identified in the electrophoretic profiles of healthy and diseased banana plants. The results further support a putative role of these enzymes in the extracellular defense repertoire of banana and, more importantly, suggest that M. fijiensis possesses a mechanism for suppression and delay of defense response in M. acuminata.Key words: Black Sigatoka, glucose 6-phosphate dehydrogenase, pathogenesis-related (PR) proteins, polyacrylamide gel electrophoresis (PAGE), retention index (Ri), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)

Testing the effectiveness of the isoelectronic substitution principle through the transformation of aromatic osmathiophene derivatives into their inorganic analogues

The objective of the current work is to evaluate the effectiveness of the isoelectronic substitution (IS) principle on a series of complexes with the general formula OsCl2(SX3H3)(PH3)(2), where X-3 represents the moieties CCC, CCB, CCN, CBN, CNB or NCB, formed by substitution of the carbon atoms in CCC by either the isoelectronic B- or N+ separately, or by both. The SX3H3 moiety forms, together with Os, an aromatic five-membered ring (5-MR) called osmathiophene. The preservation of stability and aromaticity in the resulting systems is used to indicate the effectiveness of the IS principle. The aromaticity of the proposed molecules is analyzed according to the magnetic (induced magnetic field (B-ind)) and electronic (through the multicenter index (MCI)) criteria. In addition a chemical bonding analysis on selected species is performed by the adaptive natural density partitioning (AdNDP) method

What makes a galaxy radio-loud?

We compare the Spectral Energy Distribution (SED) of radio-loud and radio-quiet AGNs in three different samples observed with SDSS: radio-loud AGNs (RLAGNs), Low Luminosity AGNs (LLAGNs) and AGNs in isolated galaxies (IG-AGNs). All these galaxies have similar optical spectral characteristics. The median SED of the RLAGNs is consistent with the characteristic SED of quasars, while that of the LLAGNs and IG-AGNs are consistent with the SED of LINERs, with a lower luminosity in the IG-AGNs than in the LLAGNs. We infer the masses of the black holes (BHs) from the bulge masses. These increase from the IG-AGNs to the LLAGNs and are highest for the RLAGNs. All these AGNs show accretion rates near or slightly below 10% of the Eddington limit, the differences in luminosity being solely due to different BH masses. Our results suggests there are two types of AGNs, radio quiet and radio loud, differing only by the mass of their bulges or BHs.Comment: 3 pages, 3 figures; to appear in Proceedings of IAU Symposium No. 284, The Spectral Energy Distribution of Galaxies (SED2011), Preston, UK, 5-9 sep. 201

Análisis modal comparado entre modelos virtuales 2d y 3d aplicado a un Cube Sat

El siguiente trabajo presenta un análisis modal comparado entre modelos virtuales 2D y 3D, para validar la sistematización de una metodología de análisis completo de Ingeniería Asistida por Computadora, ejemplificada en la aplicación a un modelo de nano satélite tipo Cube Sat. Se detallan los requerimientos de las especificaciones técnicas, condiciones estructurales, cargas, restricciones y frecuencias de vibración, que sufre este satélite al momento de su despegue y durante su órbita. Posteriormente se aplica al Diseño Asistido por Computadora la solicitud del análisis de respuesta dinámica al modelo de su estructura principal simplificada, utilizando el Método de los Elementos Finitos. Las simulaciones incluyen el análisis dinámico de frecuencias naturales y modos de vibración libre. La comparación se lleva a cabo con las herramientas de un Sistema de Ingeniería Basada en el Conocimiento que permiten optimizar la elaboración de diseños mecánicos y reducir tiempos de solución ante nuevos retos de simulación

Stochastic Approach to Enantiomeric Excess Amplification and Chiral Symmetry Breaking

Stochastic aspects of chemical reaction models related to the Soai reactions as well as to the homochirality in life are studied analytically and numerically by the use of the master equation and random walk model. For systems with a recycling process, a unique final probability distribution is obtained by means of detailed balance conditions. With a nonlinear autocatalysis the distribution has a double-peak structure, indicating the chiral symmetry breaking. This problem is further analyzed by examining eigenvalues and eigenfunctions of the master equation. In the case without recycling process, final probability distributions depend on the initial conditions. In the nonlinear autocatalytic case, time-evolution starting from a complete achiral state leads to a final distribution which differs from that deduced from the nonzero recycling result. This is due to the absence of the detailed balance, and a directed random walk model is shown to give the correct final profile. When the nonlinear autocatalysis is sufficiently strong and the initial state is achiral, the final probability distribution has a double-peak structure, related to the enantiomeric excess amplification. It is argued that with autocatalyses and a very small but nonzero spontaneous production, a single mother scenario could be a main mechanism to produce the homochirality.Comment: 25 pages, 6 figure