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Search Results: 1 - 10 of 1456 matches for " Tejada-Rosales "
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Annealing of electrophoretic YBa2Cu3O7 coatings on polycristaline substrates by zonal laser fusion
Tejada-Rosales, E.,Ondono-Castillo, S.,Diez, C.,de la Fuente, G.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2002,
Abstract: Obtaining coatings on metallic substrates of irregular geometries is not easy by traditional methods. In those cases electrochemical methods show important advantages and have been used successfully. To date only silver has shown to be inert with respect to superconducting cuprates, although progress has been made in the development of intermediate buffer layers. However, in the particular case of YBa2Cu3O7 , annealing above the cuprate superconducting melting point to attempt densification or texturing is hard on silver because of the lower melting point of the metal. . Focalized heating of superconducting oxides over metallic substrates, using LASER techniques on controlled geometries, allows densification of coatings. The Laser processed sample may be amorphous but the crystallinity is easily recovered, as well as the optimal oxygen content for the oxide, but the preferential orientation induced by the electrophoretic deposition is lost upon the recrystallization process occurring over polycrystaline substrates. La realización de depósitos de óxidos superconductores sobre substratos metálicos de geometría compleja y en general policristalinos está prácticamente basada en métodos electroforéticos o electroquímicos que permiten la utilización de un campo eléctrico de geometría definida para inducir el movimiento de partículas de óxido o de precursores de éste, hacia el electrodo elegido. Dichos métodos son fundamentales cuando el substrato es metálico o puede hacerse metálico con facilidad. Hasta el presente tan sólo la plata ha mostrado ser lo suficientemente inerte para permitir recocidos posteriores, aunque se está progresando en el desarrollo de capas “buffer”. Sin embargo, cuando el óxido depositado es YBa2Cu3O7 , el proceso de recocido posterior no permite la obtención de textura sobre Ag mediante métodos térmicos dado el inferior punto de fusión de este metal. El presente trabajo presenta un estudio de fusión zonal por láser que permite recocer el óxido sin fundir el substrato metálico de plata. El control de las distintas variables permite llegar a una solución en la que se puede preservar la naturaleza superconductora del depósito y su densificación. Ello requiere un tratamiento térmico posterior que recupera la cristalinidad y el contenido óptimo de oxígeno. Sin embargo, el tratamiento disminuye la orientación preferencial de las partículas de YBa2Cu3O7 que se obtiene mediante la deposición electroforética.
Síntesis, estructura y propiedades de transporte de nuevos óxidos complejos de cobre, plata y plomo
Tejada-Rosales, E. M.,Oro-Sole, J.,Gómez-Romero, P.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2002,
Abstract: A solid solution of formula Ag5Pb2-xCuxO6, (x = 0, 0.1, 0.3, 0.5) is reported. The synthesis was carried out by coprecipitation of Ag(I), Pb(II) and Cu(II) nitrates in alkaline media. The structure of the series is that of the parent Ag5Pb2O6, with Cu(II) occupying part of the octahedral Pb(IV) sites. This substitution induces interesting changes in the transport properties of the different members of the series, which range from metallic conductivity to semiconducting behavior. From Rietveld analysis for Ag5Pb1.5Cu0.5O6, the best fit is obtained for a model with Pb and Cu disordered occupying the octahedral site (Pm1, a = 5.8306(9) , c = 6.3430(6) , V = 187.37 3). Se presenta la síntesis y caracterización de la serie de disolución sólida Ag5Pb2-xCuxO6, (x = 0, 0.1, 0.3, 0.5). La síntesis se llevó a cabo mediante coprecipitación de los nitratos de Ag(I), Pb(II) y Cu(II) en medio básico. La estructura de la serie es la del óxido Ag5Pb2O6, con el Cu(II) ocupando parcialmente los sitios octaédricos del Pb(IV). Esta sustitución induce cambios interesantes en las propiedades de transporte eléctrico de los miembros de la serie, que van desde conductividad metálica a comportamiento semiconductor. El análisis Rietveld para el óxido Ag5Pb1.5Cu0.5O6, mostró un modelo estructural óptimo en el que Pb y Cu comparten el sitio octaédrico en una distribución desordenada (Pm1, a = 5.8306(9) , c = 6.3430(6) , V = 187.37 3).
Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes
Tejada-Rosales, E. M.,Casa?-Pastor, N.,Gómez-Romero, P.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2004,
Abstract: The anodic oxidations of copper and silver electrodes in basic media are reported. Experiments were conducted both in aqueous NaOH solutions and in a flux of molten NaOH/KOH eutectic. The oxidation processes were studied by means of cyclic voltammetry and chronoamperometries and the phases obtained were systematically characterized by x-ray diffraction. The ranges of stability of each phase in the different media studied are reported. In addition to known oxides of copper or silver, a new silver oxide was isolated. En este trabajo se describe la oxidación anódico de electrodos de plata y de cobre en medios básicos. Se han utilizado tanto medios acuosos como hidróxidos fundidos (eutéctico NaOH/KOH). Los procesos de oxidación se han estudiado mediante voltametría cíclica y cronoamperometría, y las fases resultantes han sido caracterizadas por difracción de Rayos X. Los rangos de estabilidad encontrados para cada uno dependen del medio utilizado. Además de óxidos conocidos de cobre y de plata, se ha aislado un nuevo óxido de plata.
Síntesis y Caracterización de Ag2Cu2O3, el primer óxido de cobre y plata
Tejada-Rosales, E. M.,Palacín, M. R.,Gómez-Romero, P.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2000,
Abstract: Despite the crystal-chemical similarities between copper and silver ions, there is no known silver copper oxide, neither natural nor synthetic. In this work, we present the synthesis at room-temperature of the first silver copper oxide of formula Ag2Cu2O3 (tetragonal, a=5.8857(3) , c=10.6868(7) , space group I41/amd, Z=4). It should be noted that the thermal stability of this new oxide is enhanced with respect to Ag2O or even CuO. The structure consists of alternating chains of edge-sharing square planar Cu(II) and zigzag chains of linearly coordinated Ag(I) ions. A pesar de las similitudes cristaloquímicas entre los iones de cobre y los de plata, no existe ningún óxido mixto de cobre y plata ni natural ni sintético. En este trabajo se presenta la síntesis a bajas temperaturas del primer óxido mixto de cobre y plata, de fórmula Ag2Cu2O3 (tetragonal, a=5.8857(3) , c=10.6868(7) , grupo espacial I41/amd, Z=4). Este óxido posee una estabilidad térmica superior a los correspondientes óxidos de cobre y de plata. Contiene cadenas de iones Cu(II) cuadrado-planos que alternan con cadenas en zig-zag de Ag(I) con coordinación lineal.
Electroquímica de Ag2Cu2O3 y síntesis de Ag2Cu2O4
Mu?oz-Rojas, D.,Tejada-Rosales, E. M.,Gómez-Romero, P.,Casan-Pastor, N.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2002,
Abstract: The first silver-copper mixed oxide was recently synthesized in our laboratory. Such synthesis has been possible using soft chemistry methods and low temperatures, which prevent the decomposition of silver oxides. The present work describes the electrochemical behaviour of the silver-copper mixed oxide, Ag2Cu2O3, as studied by cyclic voltametry and electrolysis, both for oxidation and for reduction reactions. This compound undergoes several redox processes when it is reduced, yielding metallic silver and metallic copper as final products. The initial oxide is not regenerated upon re-oxidation. On the other hand, when Ag2Cu2O3 is oxidized a new phase with stoichiometry Ag2Cu2O4±δ appears.The original compound can be regenerated after a new reduction. Recientemente se ha sintetizado en nuestro laboratorio el primer óxido mixto de cobre y plata. Tal síntesis ha sido posible gracias a la utilización de métodos de química suave y baja temperatura, que impiden que los óxidos de plata se descompongan. En este trabajo se describe el estudio llevado a cabo sobre el comportamiento electroquímico del óxido mixto de cobre y plata, Ag2Cu2O3 ,mediante voltametría cíclica y electrólisis tanto para los procesos de oxidación como de reducción. Dicho compuesto sufre varios procesos redox cuando es reducido, obteniéndose plata metálica y cobre metálico como productos finales, sin que se dé regeneración del óxido al volver a oxidar a éstos. En cambio al ser oxidado el Ag2Cu2O3, se observa la formación de una fase oxidada de estequiometría Ag2Cu2O4±δ a partir de la cual se puede regenerar el compuesto original.
Energizing Social Interactions at Work: An Exploration of Relationships that Generate Employee and Organizational Thriving  [PDF]
Robert M. Rosales
Open Journal of Social Sciences (JSS) , 2016, DOI: 10.4236/jss.2016.49004
Abstract:
A company’s greatest asset is its people provided they are fully engaged. In our increa-singly service-based economies, social relationships and swift coordination among employees are the means by which a lot of work gets done. Thus, whether organiza-tions and their employees flourish or languish largely depends on the quality of the so-cial connections they nurture. The quality of the workplace connections can be defined as life giving (high quality) or life depleting (low quality). Positive social interactions facilitate organizational learning, cooperation, effectiveness, and employee loyalty, among many other desirable outcomes. High-quality connections are brief, mutually beneficial, and dynamic dyadic interactions, which have the power to energize people with vital resources to do their work well. Positive psychology and positive organizational scholarship—the science of how people and organizations flourish—provides us with tools that can help bring about high-quality connections. This paper defines high-quality connections at work, examines the benefits of high- quality connections, and provides a framework for building high-quality connections. The paper shows that high-quality connections are a pathway to build individual and organizational flourishing.
?Comprar o arrendar una vivienda?: Una aplicación para el caso de la ciudad de La Paz
Tejada,Mauricio; Vidaurre,Rafael;
Desarrollo y Sociedad , 2007,
Abstract: in the city of la paz, the housing market is experiencing a favorable situation characterized by an increasing volume of available resources in the financial system, low real interest rates, a currency that is continuously being appreciated and an increase in the stock of different types of housing. in this context, the question that arises concerns the determinants of purchasing a home. among those determinants, it is possible that some socioeconomic characteristics of the families determine whether the families have access to the credit market, which leads to the fact that even though it could be optimum to purchase a home the family i obligated to rent. to model the decision of purchasing under the rationing of credit availability we follow the methodology of henderson and ioannides (1986; 1983). we found that the characteristics such as income, age, education level, and marital status of the head of household play a role in determining the possibility of having access to a credit market for the financing of a home.
Paralenguaje de los ojos en Esquilo
Flores de Tejada,Emilia;
Synthesis (La Plata) , 2004,
Abstract: the look -act of seeing, regard- has, according to contemporary research, three different functions: it informs, it touches and it speaks. this study analyses the linguistic function of the look -how the eyes "speak"-, in the aeschylus's creation, following recent studies about body language and gestures -mc neill, davis, pease, fast-, in which the eyes have a central role. these study shows that the eyes speak, flatter und denounce in aeschylus. the work presents and analyses in his literary work different types of visual expression: emblems, illustrators, regulators and adapters. finally the study analyses the messages from eyebrows, eyelids and tears. the greek language and aeschylus's genius provides plenty of interesting and valuable examples about the paralanguage of eyes.
El delito de acceso carnal homosexual en Colombia Entre la homofobia de la medicina psiquiátrica y el orden patriarcal legal
Bustamante Tejada,Walter Alonso;
Co-herencia , 2008,
Abstract: in the nineteenth century, psychiatric medicine determined the homoeroticism, invented the homosexual and proposed cures for him. in 1936 the colombian penal right criminalized those subjects. beginning from the contradictions between those institutions, this text exposes the fissures of the sexuality device that was generated to safeguard the hegemony masculinity own of heterosexual order. the medicalization showed a great diversity of homoerotiscism, and prevented the application of the rule: as an example of this is remains the memories of transvestites people that rambled by the streets of medellin, they destabilized with their own existence the established sex-generic model.
Equivalencia de Ingresos en un Duopolio Eléctrico
Alonso,Estrella; Tejada,Juan;
Cuadernos de economía , 2010, DOI: 10.4067/S0717-68212010000200003
Abstract: this article calculates the bayes-nash equilibria of a parametric family of auction models, which includes, among others, the classic models. in an analysis of two power generation firms with the same production capacity and risk neutrality, the models in this class verify a revenue equivalence result.
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