Tratamiento de depósitos electroforéticos de YBa2Cu3O7 sobre substratos policristalinos mediante fusión zonal por láser

[EN] 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.[ES] 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.The authors want to thank the Spanish Ministery of Culture (former Science and Education) for financing through grants CICYT MAT96-1057-c02-01, PB98-0491 and graduate fellowships, and REE for the contract CSIC-REE on 1997- 1998.Peer reviewe

Feature Selection Using Genetic Algorithms for the Generation of a Recognition and Classification of Children Activities Model Using Environmental Sound

In the area of recognition and classification of children activities, numerous works have been proposed that make use of different data sources. In most of them, sensors embedded in children’s garments are used. In this work, the use of environmental sound data is proposed to generate a recognition and classification of children activities model through automatic learning techniques, optimized for application on mobile devices. Initially, the use of a genetic algorithm for a feature selection is presented, reducing the original size of the dataset used, an important aspect when working with the limited resources of a mobile device. For the evaluation of this process, five different classification methods are applied, k-nearest neighbor (k-NN), nearest centroid (NC), artificial neural networks (ANNs), random forest (RF), and recursive partitioning trees (Rpart). Finally, a comparison of the models obtained, based on the accuracy, is performed, in order to identify the classification method that presents the best performance in the development of a model that allows the identification of children activity based on audio signals. According to the results, the best performance is presented by the five-feature model developed through RF, obtaining an accuracy of 0.92, which allows to conclude that it is possible to automatically classify children activity based on a reduced set of features with significant accuracy.In the area of recognition and classification of children activities, numerous works have been proposed that make use of different data sources. In most of them, sensors embedded in children’s garments are used. In this work, the use of environmental sound data is proposed to generate a recognition and classification of children activities model through automatic learning techniques, optimized for application on mobile devices. Initially, the use of a genetic algorithm for a feature selection is presented, reducing the original size of the dataset used, an important aspect when working with the limited resources of a mobile device. For the evaluation of this process, five different classification methods are applied, k-nearest neighbor (k-NN), nearest centroid (NC), artificial neural networks (ANNs), random forest (RF), and recursive partitioning trees (Rpart). Finally, a comparison of the models obtained, based on the accuracy, is performed, in order to identify the classification method that presents the best performance in the development of a model that allows the identification of children activity based on audio signals. According to the results, the best performance is presented by the five-feature model developed through RF, obtaining an accuracy of 0.92, which allows to conclude that it is possible to automatically classify children activity based on a reduced set of features with significant accuracy

Desarrollo de un Modelo 3D para un Sistema Infotainment

At present, we are witnessing the constant advance in the development of technologies for the automotive industry. Every day, there are significant advances and improvements to provide greater comfort to passengers. One of the vehicle technologies that are especially under development is designing specific user interfaces for infotainment systems and different types of interaction, for example, the implementation of 3D user interfaces to provide feedback to the user. These interfaces can be created from technologies available on the market, both free and private software for designing 3D models, and the development of Human Machine Interfaces used in the automotive industry. This article describes the process followed to develop a functional interface from technologies for 3D modeling and interface design. This interface provides visual feedback to the user that allows understanding of what is happening in the vehicle.En la actualidad somos testigos del constante avance en el desarrollo de tecnologías para la industria automotriz donde cada día hay avances y mejoras significativas para brindar mayor comodidad a los pasajeros. Una de las tecnologías del vehículo que está especialmente en desarrollo es el diseño de interfaces de usuario específicas para sistemas infotainment y diferentes tipos de interacción, por ejemplo, la implementación de interfaces de usuario 3D para proporcionar retroalimentación al usuario. Estas interfaces se pueden crear a partir de tecnologías disponibles en el mercado, tanto de software libre como privado para el diseño de modelos 3D y para el desarrollo de Interfaces Humano Máquina utilizados en la industria automotriz. Este artículo describe el proceso que se llevó a cabo para el desarrollo de una interfaz funcional a partir de tecnologías para el modelado 3D y diseño de interfaces. Dicha interfaz proporciona una retroalimentación visual al usuario que permite comprender lo que sucede en el vehículo

Synthesis, structure and transport properties of new complex oxides of copper, silver and lead

[ES]: 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) Å, c = 6.3430(6) Å, V = 187.37 Å3)[EN]: 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) Å, c = 6.3430(6) Å, V = 187.37 Å3)Este trabajo fue financiado por la CICYT (MAT98-0807- C02-02, PB98-0491). También agradecemos al Ministerio de Educación y Cultura la beca predoctoral asignada a EMT-R.Peer reviewe

Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes

[ES]: 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.[EN]: 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.This work was funded by the MCyT(Spain), Plan Nacional de Materiales (MAT2001-1709-C04-01 and MAT2002-04529-C03, MAT96- 1057-c02-01and PGC PB98-0491). We also thank the Ministry of Education and Culture (Spain) for a predoctoral fellowship awarded to EMT-R.Peer reviewe

Hake natural actomyosin interaction with free fatty acids during frozen storage

The interaction of hake muscle actomyosin with free fatty acids in 0.6 M KCl pH 7 during frozen storage has been studied up to 280 days. ATPase activity, protein solubility and relative viscosity measurements were performed. Oleic and myristic acid had a detrimental effect on these properties during frozen storage. Oleic acid was bound to the protein from the beginning, mainly to the insoluble fraction. The diminishment of functionality following addition of oleic acid is not due to aggregation caused by covalent-type bonds, since it occurs well before the electrophoretic change is appreciablePeer Reviewe

Electrochemistry of Ag2Cu2O3 and synthesis of Ag2Cu2O4

[ES]: 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.[EN]: 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.Los autores quieren agradecer al Ministerio Español de Ciencia y Tecnología por la financiación de este trabajo a través del proyecto CICYT MAT96-1057-c02-01, PB98-0491 y de becas predoctorales de D. Muñoz y E. Tejada.Peer reviewe

Síntesis y Caracterización de Ag₂Cu₂O₃, el primer óxido de cobre y plata

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)Å, c=10.6868(7)Å, 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.<br><br>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)Å, c=10.6868(7)Å, 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