WorldWideScience

Sample records for acopladas entre si

  1. ACOPLAMIENTO EXCITATORIO E INHIBITORIO DE NEURONAS PULSANTES ACOPLADAS

    Francis Armando Segovia Chaves

    2012-05-01

    Full Text Available La información es representada como patrones de actividad neuronal o pulsos, lo que crea una diferencia significante entre las redes neuronales pulsantes y las redes neuronales clásicas. Una característica diferente de las redes neuronales pulsantes es que la información es codificada en patrones de actividad neuronal y estas se comunican usando trenes de pulsos en lugar de valores individuales. Además, este tipo de redes neuronales pulsantes trabajan con una gran cantidad de neuronas donde se requiere grandes recursos computacionales para ser simuladas. En el presente trabajo se realiza un análisis teórico de las redes neuronales pulsantes,  para el caso de dos neuronas acopladas. Se logra obtener teóricamente las condiciones para acoplamiento excitatorio e inhibitorio en las neuronas.

  2. ACOPLAMIENTO EXCITATORIO E INHIBITORIO DE NEURONAS PULSANTES ACOPLADAS

    Francis Armando Segovia Chaves; Silvia Catalina Corrales Martínez

    2012-01-01

    La información es representada como patrones de actividad neuronal o pulsos, lo que crea una diferencia significante entre las redes neuronales pulsantes y las redes neuronales clásicas. Una característica diferente de las redes neuronales pulsantes es que la información es codificada en patrones de actividad neuronal y estas se comunican usando trenes de pulsos en lugar de valores individuales. Además, este tipo de redes neuronales pulsantes trabajan con una gran cantidad de neuronas donde s...

  3. Base nacional curricular comum: a falsa oposição entre conhecimento para fazer algo e conhecimento em si

    Elizabeth Macedo

    2016-06-01

    Full Text Available RESUMO: Assumindo uma visão da política como processo de signifiXação a partir da teoria do discurso de Ernesto Laclau e Chantal Mouffe, foco o atual debate sobre bases nacionais curriculares comuns no Brasil. Sendo o antagonismo social inerradicável, defendo que o terreno político é sempre marcado por articulações entre uma pluralidade de demandas. Utilizo a experiência da Austrália como ponto de partida para destacar duas ideias que se antagonizam nas discussões sobre base curricular comum no Brasil, quais sejam: conhecimento para fazer algo e conhecimento em si. Após analisar a oposição entre elas, argumento que a disputa naturaliza o sentido de currículo como controle, ideia que tento deslocar entendendo educação, justiça e democracia como porvir.

  4. Entre Freud e Foucault: a resistência como afirmação de si

    Fernanda Canavêz

    2015-07-01

    Full Text Available O artigo dedica-se ao tema da resistência para extrapolar seu entendimento como ponto de estagnação da experiência da análise. Ao contrário, o objetivo é sustentá-la como movimento de afirmação de si, de subjetivação. Para a consecução dessa proposta considera-se a multiplicidade das resistências colocada no momento mais tardio da obra freudiana para a realização de uma leitura acerca da noção no pensamento de Foucault. Nesse contexto, a resistência apresenta-se intimamente atrelada ao poder - que na perspectiva foucaultiana ultrapassa o modelo jurídico para se capilarizar nas malhas do social -, relação cujos termos não se anulam dialeticamente. A resistência figura, assim, como operador da liberdade do sujeito ante as estruturas de dominação. Por fim, aposta-se na potência da experiência psicanalítica como movimento de construção permanente dos mais diversos modos de si. As resistências seriam, portanto, o elemento a assegurar a insubmissão a uma subjetividade forjada.

  5. Les manuels scolaires bulgares au xxe siècle entre deux empires

    Deyanova, Liliana

    2015-01-01

    Sur la base de l’étude de quelques types de manuels scolaires d’histoire, je me propose d’analyser les métamorphoses du récit concernant les deux empires qui ont eu un rôle clé dans l’histoire de la Bulgarie : l’Empire ottoman et l’Empire russe. Dans la mémoire nationale bulgare, les cinq siècles de « domination ottomane » («le joug turc »), dont le pays a été libéré à l’aide de la Russie en 1878, représentent l’archétype du malheur national : cruautés, massacres, villages incendiés, conversi...

  6. Claude Liauzu, Empire du mal contre Grand Satan. Treize siècles de cultures de guerre entre l’islam et l’Occident

    Michon, Bruno

    2010-01-01

    Avec Empire du mal contre Grand Satan, Claude Liauzu, nous livre une étude ambitieuse des relations entre l’islam et le christianisme. Pour être plus exact, il cherche à se repérer dans «les atlas mentaux» – terme qu’il reprend à Fernand Braudel – qui résultent depuis des siècles des confrontations entre l’Orient islamique et l’Occident chrétien. C’est bien l’ambition de cet ouvrage que de résumer quatorze siècles d’histoire. L’objectif sous-jacent est toutefois plus qu’historique: C. Liauzu ...

  7. Medidas de Vibración de una Junta Cardánica Acoplada entre Tractor e Implemento

    Álvarez Mejía Fernando

    1990-09-01

    Full Text Available Un acelerómetro, como captador de vibraciones, fue colocado en dos posiciones estratégicas de la línea de potencia del toma de fuerza del tractor, con el fin registrar las vibraciones en las tres direcciones ocasionadas por el cambio del ángulo de la junta cardánica desde una posición cero grados (junta cardánica horizontal hasta una posición de (6° con respecto a la horizontal. De los análisis de los espectros de frecuencia de la señal registrada, se nota la existencia de una frecuencia de excitación de 18 Hz, correspondiente a la junta cardánica. Las magnitudes de los picos en los espectros de frecuencia fueron altamente significativos cuando la junta cardánica operó en el ángulo.

  8. Estudo de associação entre o Gene da Sucrase-Isomaltase (SI) e Diabetes mellitus tipos 1,2 e gestaqcional

    Josviak, Nalini Drieli

    2012-01-01

    Resumo: A Sucrase - Isomaltase é uma glicoproteína integral de membrana codificada pelo gene Sucrase - Isomaltase ( SI ; 3q25 - q26 ) , exclusivamente expressa nas microvilosidades do intestino delgado e responsável pela digestão terminal de sacarose e amido . Sabe-se que em Diabetes Mellitus há um aumento na atividade de dissacaridases, incluindo a sucrase-isomaltase , mas até agora nenhum estudo de associação foi descrito entre a expressão aumentada e / ou atividade da sucrase - isomaltase ...

  9. OPTIMIZACIÓN DEL MÉTODO DE MICROEXTRACCIÓN EN FASE SÓLIDA ACOPLADA A CROMATOGRAFÍA GASEOSA PARA ANÁLISIS DE METANOL EN AGUA

    Fidel Granda

    2011-12-01

    Full Text Available Se optimizó la técnica de microextracciónen fase sólida acoplada a cromatografíagaseosa con detector de ionizaciónde flama (HS-SPME/GC-FID por sunombre en inglés para análisis de metanolen agua utilizando diferentes microfibras,una fibra de poliacrilato y una fibrade polidimetilsiloxano y una columnaRTX-5. Las variables evaluadas fuerontiempo de absorción del contaminante enla fibra, volumen libre en el vial, tiempoy temperatura de desorción y efecto dela agitación y presencia de sal en el sistema.De acuerdo con los resultados, eltiempo óptimo de absorción es 15 minutos,el volumen de muestra es 5 mL. Seencontró que existe una íntima relaciónentre la temperatura de desorción y el área del pico cromatográfico, y una correlaciónR2 = 0,99965 para la curva decalibración elaborada en un rango entre0 y 50%, considerando el origen, con unlímite de detección de 0,01% y un límitede cuantificación del 0,04%.

  10. Les relations entre les acteurs locaux et le Conseil des bâtiments civils dans la première moitié du XIXe siècle à Bourges, Colmar et Laval.

    Bondon, Anne

    2013-01-01

    Cet article présente les relations complexes entre le Conseil des bâtiments civils et les acteurs locaux (municipalités, architectes) autour de la question des transformations architecturales et urbaines dans la première moitié du XIXe siècle.

  11. La nisba tribale entre identification individuelle et catégorisation. Variations dans la Sicile des xe-xiie siècles

    Annliese Nef

    2013-06-01

    Full Text Available Il s’agit ici de cerner le rôle de la nisba tribale dans le cadre de l’identification par l’anthroponymie en Sicile entre le xe et le xiie siècle. Les sources considérées permettent, pour une part (chroniques, ouvrages de ṭabaqât, de retracer le contexte dans lequel s’insèrent les documents locaux analysés, tous fruits de la pratique administrative ou notariale. Le foisonnement du nom islamique permet de décliner des dénominations sélectives en fonction du contexte et la nisba tribale n’est pas un élément décisif de l’identification par la dénomination individuelle dans la Sicile des xie-xiie siècles. Arborée par les savants et, surtout, quasiment obligatoire pour les témoins énumérés dans les actes notariés, elle qualifie les élites urbaines et est un signe d’appartenance à une aristocratie, à une notabilité. En revanche, dans les zones rurales, documentées partiellement par des listes fiscales, elle apparaît très effacée. La nisba tribale véhicule d’autres éléments (honorabilité, appartenance aux élites, etc. que ceux strictement nécessaires à l’identification personnelle. Elle n’individualise pas mais identifie en renvoyant à un groupe, ici la tribu et sa célébrité. Il s’agit donc plus d’un élément de catégorisation que d’individuation.

  12. Entre ville et campagne, la villégiature à Angers (Maine-et-Loire au XIXe siècle

    Dominique Letellier-d'Espinose

    2009-11-01

    Full Text Available Quelles formes prend au XIXe siècle la villégiature dans les proches abords d’une ville de taille moyenne comme Angers ? Le sujet est particulièrement riche durant cette période de forte urbanisation où s’interpénètrent une campagne de proximité avec son héritage patrimonial et les quartiers suburbains, nouveaux espaces « résidentiels ». La frontière mouvante entre espace rural et urbain, comme la notion floue et évolutive de temporalité qui met à mal la distinction entre résidences permanentes et temporaires, rejoint les désirs de nature du citadin ou de confort moderne du châtelain bien analysés par le théoricien Daly. Ce phénomène sociétal se traduit par des expressions architecturales souvent ambivalentes, que différencie surtout la relation au lieu. Du front urbain au chemin rural, du jardin paysager miniature au parc domanial, le paramètre contextuel est évidemment déterminant dans l’appréhension d’une villégiature de bord de ville.What are the forms of countryside retreat during the nineteenth century in the immediate vicinity of a medium-sized town such as Angers? The subject is a remarkably stimulating one during this period which saw the expansion of the town into the surrounding countryside where an existing heritage of country houses was now joined by new ‘residential’ spaces of suburban neighbourhoods. The fluctuating frontier between urban and rural space, along with evolving notions of the occupation of time, making the distinction between a permanent and a holiday residence uncertain, find an echo in the theories of Daly about the town-based desires for modern comfort shared by the class of country house owners. The societal phenomenon finds expression in architectural terms which is often ambivalent, producing differences in relation to specific places. From the urban street front to the rural lane, from the miniature landscaped garden to the estate park, contextual parameters are

  13. Les réseaux économiques dans le secteur de la mode vestimentaire à Shanghai entre la fin du XIXe siècle et les années 1930

    Brasó-Broggi, Carles

    2015-01-01

    L’industrie de la mode à Shanghai s’est développée entre les dernières décennies du XIXe siècle et les années 1930, et a joué un rôle important dans l’industrialisation du pays. Cet article tente de définir la relation entre la production et la consommation dans l’industrie textile de Shanghai. Une des caractéristiques de la mode est sa capacité à innover en créant de nouvelles tendances distinctes tout en absorbant différentes influences et la mode shanghaïenne au début du XXe siècle était u...

  14. Modelación acoplada de aguas superficiales y subterráneas para la gestión conjunta del recurso hídrico.

    Estrada Restrepo, Óscar Andrés; Vélez Upegui, Jaime Ignacio; Restrepo Tamayo, Carlos Augusto; Vélez Otálvaro, María Victoria

    2010-01-01

    Se presenta una metodología de modelación acoplada de aguas superficiales y subterráneas a partir de la integración de un modelo de flujo subterráneo (MODFLOW) con un modelo hidrológico que permite estimar la producción de escorrentía superficial y la recarga de los acuíferos, para tener una aproximación cuantitativa de la interacción río-acuífero y que sirva como herramienta de apoyo para tomar decisiones en la gestión del uso conjunto de aguas superficiales y subterráneas.

  15. Comparison of energy expenditure and closed-loop performance of thermal and reactive distillation sequences coupled for biodiesel production; Comparacion de gasto energetico y desempeno a lazo cerrado de secuencias de destilacion reactiva y termicamente acopladas para produccion de biodiesel

    Cornejo-Jacob, J.L [Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoacan (Mexico); Vazquez-Ojeda, M; Segovia-Hernandez, J.G; Hernandez, S [Universidad de Guanajuato, Guanajuato, Guanajuato (Mexico); Maya-Yescas, R. [Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoacan (Mexico)]. E-mail: rmayay@umich.mx

    2013-03-15

    Biodiesel is the common name for fatty acid methyl esters, obtained by esterification (basic catalysis) or trans-esterification (acid catalysis) of vegetable or animal oils with alcohols, and used as liquid fuel. Production involves the reaction, under mild conditions, between the oil and, typically, excess of methanol. Traditional production of biodiesel exhibits some handicaps, such as the shift of equilibrium to fatty acids by using excess of alcohol that must be separated and recycled. As alternative, it is possible to integrate reaction/separation operations into a single intensified unit, a reactive distillation column, followed by a second separation unit. These configurations exhibit several advantages such as shifting equilibrium in the reactive region and, because of the thermal integration with the second unit, energy savings during products separation. In order to design these production sequences taking advantage of steady state knowledge (energy savings) and considering dynamic performance, this work performs a controllability analysis for six possible configurations; open-loop control properties, evaluated by single value decomposition, are probed by implementing PI controllers to the system. The reactive distillation column coupled to a stripper, without reboilers, shows to be the best option in terms of closed-loop performance and energy savings. [Spanish] Biodiesel es el nombre comun dado a metil esteres de acidos grasos obtenidos por esterificacion (catalisis basica) o trans-esterificacion (catalisis acida) de aceites animales o vegetales con alcoholes, y usados como combustibles liquidos. Su produccion involucra la reaccion entre el aceite y, tipicamente, exceso de metanol a condiciones moderadas. La produccion tradicional de biodiesel exhibe algunas desventajas como el desplazamiento del equilibrio hacia acidos grasos debido al exceso de alcohol, que debe ser separado y reciclado. Alternativamente, es posible integrar las operaciones reaccion

  16. Le réformateur, le prince et l’infidèle, entre Aragon et Silésie (XIVe-XVe siècles

    Ludovic Viallet

    2010-06-01

    Full Text Available A partire dal libro di Paolo Evangelisti, l'Autore si sofferma, nell'ambito del contributo dato dai Francescani alla costruzione dello Stato, sulla questione degli usi del "paradigma" Passio Christi e corpo mistico, della riforma, per quanto attiene il controllo sociale e i simboli identitari, e del sacro.

  17. Le réformateur, le prince et l’infidèle, entre Aragon et Silésie (XIVe-XVe siècles)

    Ludovic Viallet (a cura di)

    2010-01-01

    A partire dal libro di Paolo Evangelisti, l'Autore si sofferma, nell'ambito del contributo dato dai Francescani alla costruzione dello Stato, sulla questione degli usi del "paradigma" Passio Christi e corpo mistico, della riforma, per quanto attiene il controllo sociale e i simboli identitari, e del sacro.

  18. la invención de la diferencia entre Argentina y Brasil (o para qué sirve el fútbol, si es que sirve para algo)

    Alabarces, Pablo

    2006-01-01

    El trabajo analiza el uso de estereotipos en las narrativas sobre la identidad nacional a través del fútbol en la Argentina y Brasil, partiendo de un primer análisis realizado por la antropóloga brasileña Simoni Lahud Guedes. Se intenta analizar, a través de la revisión bibliográfica y la utilización de materiales provenientes de fuentes diversas –sociológicas, antropológicas, históricas– el modo en que la diferencia entre ambos países fue narrada, en el uso de los estereotipos de tropicalism...

  19. Le diplomate vénitien entre les XVIe et XVIIIe siècles : statut, rôles et fonctions

    Antonio TRAMPUS

    2013-01-01

    Le but de cet article est de présenter la figure du diplomate vénitien, ses caractéristiques et ses fonctions, pour comprendre dans quelle mesure et pourquoi ces ambassadeurs sont devenus un modèle pour les Etats européens. Le modèle théorique de la diplomatie vénitienne aux XVIIe et XVIIIe siècles est comparé avec son fonctionnement pratique dans le cadre de la politique de neutralité et du déclin économique de la République. La description du cas de Venise offre des preuves pour une relectu...

  20. Art et autoreprésentation : la figure du pape entre le xie et le xive siècle

    Paravicini Bagliani, Agostino

    2013-01-01

    Les études de ces dernières décennies ont montré que les papes des xie au xiiie siècles ont élaboré une autoreprésentation très riche en recourant à une créativité métaphorique, symbolique et rituelle qui a placé au centre de l’attention le corps du pape lui-même. Les études sur le mécénat artistique ont mis en évidence la place centrale de la Rome pontificale dans le panorama artistique européen, grâce à la présence d’artistes tels que Pietro Cavallini, Jacopo Torriti et Arnolfo di Cambio. I...

  1. Via Lyon: Parcours de romans et mutations éditoriales au XVIe siècle. Partie II. La circulation des textes entre Lyon et Paris

    Gaëlle Burg

    2015-07-01

    Full Text Available La première partie du dossier Via Lyon (Carte Romanze 2/2 [2014] analysait le rôle de carrefour économique et culturel de la ville de Lyon dans la constitution d’une identité éditoriale des romans publiés en France au XVIe siècle. L’étude de ces «parcours de romans» conduit à replacer, en cette seconde partie du dossier, la notion d’«étape lyonnaise» dans la dynamique qui anime les deux principaux centres d’imprimerie français de la Renaissance. L’étude des pérégrinations éditoriales, de Paris à Lyon et de Lyon à Paris, de Lancelot du Lac (G. Burg, de Valentin et Orson (M. Colombo Timelli et de Méliadus chevalier de la Croix (A. Réach-Ngô met ainsi au jour les diverses formes de circulation, d’adaptation et de réappropriation que les ateliers parisiens et lyonnais confèrent aux œuvres romanesques qui passent sous leurs presses tout au long du siècle. The first part of the file Via Lyon (Carte Romanze 2/2 [2014] analyzed the role of economic and cultural crossroad of Lyon city in the constitution of an editorial identity of novels published in France in the sixteenth century. The study of these «novels’ route» leads to situate the concept of «Lyon step» in the dynamics which animates the two major French printing centers of the Renaissance. The editorial peregrinations, from Paris to Lyon and from Lyon to Paris, of three french novels, Lancelot du Lac (G. Burg, Valentin and Orson (M. Colombo Timelli and Méliadus chevalier de la Croix (A. Réach-Ngô, shows the various forms of circulation, adaptation and reappropriation that various Parisian and Lyon workshops give to novels they print throughout the century. 

  2. La patria criolla entre localisme exacerbé et solidarité continentale dans la vice-royauté de Lima au XVIIe siècle

    Bernard Lavallé

    2012-01-01

    Full Text Available Cet article montre comment le créolisme andin du XVIIe siècle fonctionnait et s’affirmait notamment par rapport à une relation très forte à son environnement immédiat, la patria, d’où sa forte coloration localiste et la faible présence dans son discours, voire l'absence, de référents géographiques plus vastes. Il lui était cependant possible d’élargir son regard, et lorsqu’il devait faire face en Espagne aux préjugés péninsulaires, il pouvait aussi faire preuve d'une conscience américaine continentale.Este artículo muestra como el criollismo andino del siglo XVII funcionaba y se afirmaba a partir de une relación muy fuerte con su entorno inmediato, la patria. De ahí su fuerte coloración localista y la escasa presencia, o la ausencia, en su discurso de referentes geográficos más amplios. Sin embargo le era posible ensanchar su mirada, y cuando tenía que enfrentarse en España con los prejuicios peninsulares podía también manifestar una conciencia continental.

  3. Le corps entre sacré et profane : la réforme des pratiques pèlerines en Égypte (xixe-xxe siècles

    Catherine Mayeur-Jaouen

    2006-11-01

    Full Text Available Les pèlerinages annuels aux tombes des saints, les mouleds, sont l’un des phénomènes saillants de la culture religieuse égyptienne, aussi bien pour les coptes que pour les musulmans. Nés à la fin de l’époque mamelouke, les mouleds n’ont été décrits soigneusement que par leurs détracteurs, notamment les réformistes musulmans de la fin du xixe siècle et de l’entre-deux-guerres, ou par les voyageurs européens du xixe siècle, épris de pittoresque et de scandale. Tous s’entendent pour relever ou dénoncer l’exaltation du corps qu’entraînent les mouleds, et pour relever le “mélange de sacré et de profane” qui caractérise ces fêtes et où le corps est le véhicule principal du sacré. Ce qui choque, c’est de voir les pèlerins associer les dévotions à la danse, les prières à la fête foraine, l’élan vers Dieu à la pantomime obscène, le pèlerinage aux satisfactions du corps dans ses besoins les plus triviaux, le miracle à la prostitution.Les efforts conjugués de l’État égyptien et des clercs musulmans réformistes se sont donc employés, depuis la fin du xixe siècle, à “spiritualiser” les pèlerinages. Les tenants du Renouveau copte, plus récemment mais encore plus efficacement, se sont joints aux musulmans pour “épurer” les mouleds. Chez les coptes comme chez les musulmans, distinguer profane et sacré revient à séparer corps et âme. Le refus de la culture folklorique où s’ancraient les usages pèlerins du corps est devenu le discours officiel : il renvoie à une conception sécularisée du sacré où le corps n’a plus sa place.

  4. Detección quimioluminiscente acoplada a la cromatografía iónica y a sistemas de inyección en flujo para determinar iones metálicos y propiedades antioxidantes de productos naturales.

    Carrasquero Durán, Armando

    2010-01-01

    Detección quimioluminiscente acoplada a la cromatografía iónica y a sistemas de inyección en flujo para determinar iones metálicos y propiedades antioxidantes de productos naturales El propósito de esta tesis fue el de desarrollar métodos analíticos basados en la detección quimioluminiscente para la determinación de iones metálicos y de las propiedades antioxidantes de sustancias orgánicas. En ese sentido, se acopló la detección quimioluminiscente basada en la oxidación del luminol a la c...

  5. Correlations between thermogravimetric analysis and gas chromatography techniques with mass spectrometry in fuels analysis; Correlacao entre as tecnicas termogravimetrica e cromatografia gasosa acoplada a espectrometria de massas na analise de combustiveis

    Fonseca, Marcelo Marques da; Yoshida, Maria Irene; Fortes, Isabel Cristina Pereira [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica]. E-mail: mmfon@terra.com.br; mirene@dedalus.lcc.ufmg.br; fortesic@dedalus.lcc.ufmg.br

    2003-07-01

    Gasoline is a complex mixture of paraffinic, naphtenic, olefinic and aromatic hydrocarbons, whose ebullition strip varies of 30 to 220 deg C. Its composition is function of the types of processes used for its production. The increase of the consumption of this fuel requests larger control to guarantee the quality and safety of the population that it is committed for the adulteration by solvent addition. Monitoring of the quality of the gasoline is made, mainly, for the distillation - ASTM D86. This work has as objective to evaluate the thermal behavior of the gasoline automotive, type C(with and without adulteration) by Thermal analysis (TG, DTG) and to got parameters that allow to certify the adulteration for comparison with the standard curve. Beyond that samples were analyzed by CG/EM seeking a correlation among both . Samples were prepared for addition of 22% of alcohol ethyl anhydrous to reference gasoline produced by the Gabriel Passos Refinery (REGAP) and adulterated with solvents of several natures. TG curves were obtained in equipment model SHIMADZU-TGA- 50H .Chromatographic features and their respective mass spectra were obtained in the equipment CG/MSQP5050 of Shimadzu. The observation of the data experimental exhibition a displacement of the TG curve in relation to the standard sample. Variation happens in function of the type of mixture of solvents used in the adulteration and of the amount added to the fuel. (author)

  6. Correlação entre permeabilidade e resistência mecânica de filtros cerâmicos no sistema Al2O3-SiC Relationship between permeability and mechanical strength of Al2O3-SiC ceramic filters

    V. R. Salvini

    2000-06-01

    Full Text Available Tem sido crescente o uso de cerâmicas reticulares em processos de refino e purificação de metais fundidos, filtração de gases quentes e combustão catalítica. A aplicação depende da composição química e das propriedades físicas do material (número de poros por polegada linear (ppi, porosidade e diâmetro de poro. Há um consenso de que a melhoria das propriedades dos filamentos resulta em um melhor desempenho mecânico do filtro cerâmico. Entretanto, a análise dos valores de resistência mecânica não pode ser considerada isoladamente, uma vez que para filtros cerâmicos esta tem que estar associada à permeabilidade. Neste trabalho é feita uma análise entre as propriedades fluidodinâmicas e mecânicas de filtros cerâmicos no sistema Al2O3-SiC na faixa de 8 a 90 ppi. Os resultados obtidos permitem considerações tanto no aspecto do processamento cerâmico quanto no modelamento mecânico apresentado na literatura.Reticulate ceramics have been increasingly employed in purification of gases, liquid metals and in catalytic processes. The application area usually depends on the chemical composition and the physical properties (porosity, pore size and pore counting (ppi. In most cases, reticulate ceramics are submitted to compression loads at high temperatures, which makes the durability of these cellular materials be ultimately related to the mechanical quality of the struts. In filtration applications, it is also important the evaluation of fluid dynamic properties of the ceramic, specifically its permeability to fluid flow. In this work, a relationship between mechanical properties and permeability constants of Al2O3-SiC ceramic foam filters with 8 to 90 ppi is presented. Results were associated with the processing technique and with the mechanical modeling presented in the literature.

  7. Scènes de plage dans la peinture hollandaise du XVIIe siècle: l'entrée de la plage dans l'espace des citadins

    Rémy Knafou

    2000-06-01

    Full Text Available Les scènes de plage sont une catégorie de la peinture hollandaise, inventée au XVIIe siècle. L'analyse d'un corpus de tableaux peints durant le Siècle d’Or permet de montrer que le «désir de rivage» analysé par Alain Corbin est apparu sur le littoral de la mer du Nord dès le XVIIe siècle avec l'ouverture de la plage aux citadins oisifs venus des villes voisines.

  8. (E-2-Nonenal determination in brazilian beers using headspace solid-phase microextraction and gas chromatographic coupled mass spectrometry (HS-SPME-GC-MS Determinação de (E-2-nonenal em cervejas brasileiras utilizando microextração em fase sólida do headspace e cromatografia gasosa acoplada a espectrometria de massas

    Rodrigo Scherer

    2010-05-01

    Full Text Available (E-2-nonenal is considered an important off-flavor of beer, related to the flavor of beer staling. In this study, a new method for determination of (E-2-nonenal in beer using headspace solid-phase microextraction and gas chromatographic coupled mass spectrometry (HS-SPME-GC-MS was developed and applied in Brazilian beer samples. The extractions were carried out in CAR-PDMS (carboxen-polydimethylsiloxane fiber and the best results were found with 15 minutes of equilibrium and 90 minutes of extraction at 50 °C. The method was linear in the range from 0.02 to 4.0 μg.L-1 with correlation coefficient of 0.9994. The limits of detection and quantification were 0.01 and 0.02 μg.L-1, respectively. 96.5% of recovery and 4% precision (RSD were obtained in the fortification of beer samples with 2.0 μg.L-1 of (E-2-nonenal. The developed method proved to be simple, efficient and highly sensitive to the determination of this analyte being easily applied in the quality control of the brewery. (E-2-nonenal was found in all beer samples analyzed with levels between 0.17 and 0.42 μg.L-1.O (E-2-nonenal é considerado um importante off-flavor da cerveja, sendo relacionado ao sabor de cerveja envelhecida. Neste estudo, um novo método para determinação de (E-2-nonenal em cerveja usando microextração em fase sólida do headspace e cromatografia a gás acoplada à espectrometria de massa (HS-SPME-GC-MS foi desenvolvido e aplicado em amostras de cerveja brasileira. As extrações foram realizadas utilizando a fibra CAR/PDMS (carboxen/polidimetilsiloxano, com 15 minutos de tempo de equilíbrio e 90 minutos de exposição da fibra a 50 °C. O método foi linear na faixa de 0,02 e 4,0 μg.L-1, com coeficiente de correlação de 0,9994. Os limites de detecção e quantificação foram 0,01 e 0,02 μg.L-1, respectivamente. Foram obtidos 96,5% de recuperação e 4% de variação entre replicatas de amostras de cerveja fortificadas com 2,0 μg.L-1 de (E-2-nonenal. O m

  9. Entre la vigne et la croix. Dionysos dans les discours littéraires et figurés chrétiens (iie-ive siècles)1

    Massa, Francesco

    2013-01-01

    Mon doctorat est consacré à l'analyse du rôle du dieu grec Dionysos dans la production littéraire et figurée chrétienne des premiers siècles de l'époque impériale romaine (iie-ive siècles). La recherche s'inscrit dans deux courants d'études principaux : le premier renouvelle l'analyse des contacts religieux pendant les premiers siècles de notre ère, en proposant d'éclairer comment les situations de contact interviennent dans la formation et la définition des identités religieuses ; le deuxièm...

  10. L'Afrique noire telle que l'occident la percoit (XVème - XVIIIème siècles) entre mythes et réalités

    Diop, Brahim

    2010-01-01

    L'Occident médiéval a élaboré, dans sa curiosité pour le monde environnant, des images diverses sur l'Afrique Noire et ses habitants. Celles-ci reposent sur un savoir essentiellement livresque. Car, jusqu'au milieu du XVè s., à cause des multiples obstacles naturels (Sahara, Océan Atlantique), politiques et culturels (Islam...), les contacts réels entre les deux continents sont demeurés inexistants. Ces images ont aussi, pendant longtemps, été particulièrement marquées, non seulement par la c...

  11. Les relations diplomatiques entre le monde musulman et l’Occident latin (XIIe-XVIe siècles). Vol. spécial d’Oriente Moderno, vol. 88/2, 2008, vi + 229-533 p.

    Piemontese, Angelo-Michele

    2013-01-01

    Michele Bernardini, « Introduction » (p. i-vi), illustre l’entreprise historiographique d’envergure internationale dont ce volume est le fruit, grâce à la coopération entre le CNRS, Paris - Unité mixte de Recherche 8167 « Orient et Méditerranée » (Laboratoire : Islam médiéval), l’École Pratique des Hautes Études (Paris, Sorbonne), l’Institute of Asian and African Studies (University of Jerusalem) et l’Istituto per l’Oriente, Rome. Le but du recueil consiste à examiner l’histoire des relations...

  12. Anne-Sophie Bruno, Éric Geerkens, Nicolas Hatzfeld, Catherine Omnès (dir.), La santé au travail, entre savoirs et pouvoirs (19e-20e siècles)

    Lecomte-Ménahès, Gabrielle

    2013-01-01

    Deux ans après la parution de Cultures du risque au travail et pratiques de prévention au xxe siècle, une équipe dirigée par Anne-Sophie Bruno, Eric Geerkens, Nicolas Hatzfeld et Catherine Omnès publie un nouvel ouvrage collectif sur la santé au travail. Alors que l’opus de 2009 abordait la prévention des risques professionnels sous l’angle des pratiques et des cultures professionnelles des acteurs impliqués, distingués selon leur statut (professionnels de la prévention, acteurs des instances...

  13. Pratiques de l’espace hospitalier par les religieuses au XIXe siècle dans les hôpitaux parisiens : préserver un entre-soi religieux et féminin ?

    Jusseaume, Anne

    2016-01-01

    Au XIXe siècle, les sœurs hospitalières, bien que théoriquement séparées du monde et disposant d’espaces et de temps propres à leur vie religieuse, sont pourtant quotidiennement au contact d’ecclésiastiques, d’hommes et de femmes laïques qu’ils soient malades ou personnels hospitaliers. Il ne s’agit pas ici de questionner la clôture avec le monde extérieur, ou l’enfermement des sœurs et des malades au sein des hôpitaux, déjà abordés par l’historiographie, mais plutôt de déplacer le regard ver...

  14. Aude Mairey, Une Angleterre entre rêve et réalité. Littérature et société dans l’Angleterre du 14e siècle

    Doudet, Estelle

    2008-01-01

    Depuis une trentaine d’années, les études inspirées par le New Historicism ont fait évoluer le statut des textes littéraires dans la recherche historique. D’objets marginaux, ils sont devenus de véritables sources. Par un mouvement complémentaire, la Nouvelle Philologie a orienté plus résolument les études littéraires vers le couple désormais indissociable « texte/contexte ». L’historienne Aude Mairey propose ici une étude socio-culturelle de l’Angleterre au 14e siècle. On sait qu’outre les t...

  15. Entre texte et image, enquête sur les vitraux historiés du xiiie siècle de la cathédrale Saint-Étienne de Sens

    Claire Pernuit

    2010-10-01

    Full Text Available Tel qu’il apparaît aujourd’hui, l’ensemble des vitraux historiés du xiiie siècle de la cathédrale Saint-Étienne de Sens se compose de sept récits complets : quatre fenêtres basses du déambulatoire nord ont reçu des verrières réalisées vraisemblablement après l’achèvement de la cathédrale, soit autour des années 1200-1210 – vitraux hagiographiques de saint Thomas Becket et de saint Eustache, vitrail légendaire de la parabole du Fils Prodigue, vitrail typologique de la parabole du Bon Samaritai...

  16. Entre itinéraires et trajets : représentations des déplacements dans les guides de voyage au tournant du XIXe siècle

    Ariane Devanthéry

    2011-06-01

    Full Text Available Un itinéraire est plus qu’une route : c’est une route sélectionnée, choisie par une époque et jalonnée de savoirs, de devoirs et d’émotions. Le Grand Tour ayant connu des itinéraires fortement codés, comment se fait le passage au tourisme ? En douceur ou avec fracas ? Y a-t-il alors abandon de tout itinéraire, invention de nouveaux cheminements ou redéfinition ? Et si la transformation du Grand Tour en tourisme se jouait aussi dans les manières de mettre en scène l’espace des voyages ?An itinerary is more than a route: it is a selected route, chosen by a time and lined with knowledge and emotions. As the Grand Tour had known some strongly coded itineraries, how does the transition to tourism happen? Smoothly or with a crash? Is then a giving up of all itineraries, new ways invented, or redefinition? And what if the Grand Tour converting into tourism was also been acted in the way of displaying the travelling space?

  17. Entre exotisme et nostalgie

    Caroline Rozenholc

    2008-03-01

    agglomération et à promouvoir l’identité globalisée de la ville ? Pour répondre à cette question, et pour contribuer à celle plus vaste de l’attachement au lieu dans la mondialisation, Florentin sert d’ancrage à une réflexion sur le quartier qui permet d’alimenter, entretiens et observations à l’appui, le débat entre tenants de l’hyper-mobilité et des nons-lieux et ceux d’une territorialité au fondement de la géographie et de l’urbanité. Florentin, espace complexe et stimulant, et dont on peut multiplier les « entrées », semble alors indiquer une troisième voie ; celle d’un lieu défini et ouvert où s’articulent, sans s’effacer, des temporalités et des perceptions du lieu distincts et propres, même si parfois partagées, à chacun.Florentin between exoticism and nostalgia.Globalization of an 'authentic' neighborhoodAt the beginning of the 90s, the Municipality of Tel-Aviv, approached by a small group of inhabitants of Florentin neighborhood, decides to invest in it. Florentin, at the time, is one of the poorest areas of the city and alike the whole South of Tel-Aviv, it is in an advanced state of deterioration. Over the last twenty years, buildings had fallen apart and all the population who had opportunities to leave the neighborhood found better dwellings. At the time, the potential of the neighborhood is nevertheless clear to the authorities – due to its peculiar architecture and the interesting mixture of residential and commercial activities – and the successful rehabilitations of both Neve Tseddek (the first Jewish neighborhood out the walls of the ancient Jaffa and Sheinkin street (today a very hype place to hang out stimulate the Municipality to “put Florentin back on the map”. This is a radical step as for few decades Florentin remained very much at the margins of the city, in between Tel-Aviv and Jaffa, only loosing population and gaining in polluting activities, such as small industries and manufactures. After few

  18. L’irresponsabilité pénale dans la première moitié du XIXe siècle, entre classicisme et défense sociale

    Laurence Guignard

    2005-07-01

    Full Text Available Nous tentons de saisir, dans cet article, l’évolution de la doctrine pénale du xixe siècle concernant la question de l’irresponsabilité des déments exprimée dans l’article 64 du code pénal. La doctrine, initialement fondée sur la théorie classique d’un sujet doté d’une volonté libre, qui impose des peines fixes à fonction principalement rétributive, voit émerger progressivement une conception graduée de la responsabilité dont la mesure se fait en fonction de la santé mentale des accusés. Ce nouveau système suppose la mise en place de peines individualisées dans le cadre d’une justice dont la protection de la société est le premier souci. Dans ce processus, les doctrines libérales des néoclassiques ont joué un rôle clef.This abstract deals with the transformation of the penal doctrine during the xixth century. The question of irresponsiblity of the insane contained in the article 64 of the penal code changed during this periode from retributive justice to preventive justice. At the beginning of the century, the legal anthropology of the penal Code of 1810 is founded on the classical theory of a subject with free will. In consequence, no possibility for gradual punishment existed. Progressively, we see emerging a conception of graduated responsability which is a function of the mental sanity of the accused. This new penal system takes place within a legal frame that aimes primarily to protect the society. In this process, liberal neoclassical doctrines play a major role.

  19. La communication entre parents migrants et enseignants

    Frei, Nathalie; Schertenleib, Georges-Alain

    2014-01-01

    La communication entre l’école et la famille semble être une composante essentielle (parmi tant d’autres d’ailleurs !) qui permettrait à l’enfant d’apprendre et d’évoluer sereinement. Elle n’est pourtant pas toujours bien vécue de part et d’autre car il arrive que certains malentendus surviennent. En effet, les enseignants de nos jours ont des contacts avec des familles d’origines très variées et doivent savoir faire preuve d’adaptation face à cette diversité. Même si la tâche est quelques fo...

  20. Administrer le vestiaire royal. Entre drap de Sedan et fleurs artificielles, les Menus Plaisirs et le vêtement à la cour de France du XVIIIe siècle

    Pauline Lemaigre-Gaffier

    2012-11-01

    Full Text Available Impliqués dans la gestion financière et comptable de la Maison du Roi, comme dans l’organisation matérielle du cérémonial royal, les Menus Plaisirs jouent un rôle clef dans la ritualisation d’une vie de cour essentielle à la représentation de la majesté royale et de l’État monarchique. Ils participent dans ce cadre aux pratiques vestimentaires (confection, entretien, transport, transformation, don des vêtements et accessoires engendrées par les exigences du paraître curial. Du financement de la garde-robe du souverain à l’habillement de ses serviteurs ou de ses comédiens, les Menus sont en effet responsables d’un ample vestiaire. Sa variété est à l’image de leurs compétences, elles-mêmes liées à la mise en œuvre d’un cérémonial globalisant, et à l’aune d’un microcosme aulique censé donner à voir une société structurée par le service du roi. Il s’agira ainsi d’explorer la culture matérielle de cour en même temps que l’esprit des institutions d’Ancien Régime, en analysant l’association des Menus Plaisirs à la Garde-Robe dans « l’habillement du roi », puis la production par les Menus d’un vestiaire déployé entre cour et ville, et, enfin, les principes et tensions sous-jacents à leur gestion de la vie de cour.The « Menus Plaisirs » Administration and Royal Clothing in the 18th century French Court - Implied as much in the financial and accounting management of the French Royal Household as in the material arrangements of the ceremonies, the “Menus Plaisirs” administration played a key part in the court life the ritualization of which was essential to the monarchy representation system. They contribute to every kind of clothing practices due to court appearances rules. From the king’s wardrobe financing to his servants and actors’ clothing, the “Menus Plaisirs” administration was indeed responsible of a large range of supplies. These ones were as diversified as

  1. Burnout entre audiologistas

    Ferreira, Ana Luísa Simões Marques

    2015-01-01

    A escassez de recursos e a pressão das instituições para obter resultados estão a levar cada vez mais profissionais ao esgotamento físico e emocional. Um estudo da OCDE, evidência a ligação entre problemas psicológicos e condições de trabalho em 15% a 20% da população ativa. Portugal ocupa o sétimo pior lugar, entre os 34 países pertencentes a esta organização. O burnout é a fase final de uma situação de stresse profissional crónico, apresentando o seu foco principal na exaustã...

  2. Amor entre mulheres

    Costa, Vera de Sá Nogueira Botelho da

    2014-01-01

    Dissertação de Mestrado apresentada ao ISPA - Instituto Universitário A literatura psicanalítica evidencia a falta de estudos sobre o amor na homossexualidade feminina. No âmbito de um estudo qualitativo, esta dissertação pretendeu explorar as relações amorosas de seis mulheres homossexuais, com idades compreendidas entre os 36 e os 53 anos, tendo em conta o desenvolvimento da sua identidade, os seus objectos internos, as suas relações de objecto e as suas identificações. O mét...

  3. Entre terre et territoire

    Pirinoli, Christine

    2003-01-01

    La mémoire collective et les identités palestiniennes se (re)produisent à partir des référents symboliques centraux que sont la terre villageoise, le territoire, la nation et le transnational. Avec la perspective de la création d'un État palestinien, l'instrumentalisation, populaire et officielle, de ces notions rend particulièrement saillant le processus de réinterprétation qui est à l'oeuvre. Si ces concepts restent fondamentaux pour la majorité des Palestiniens, notamment en regard d...

  4. Relaciones entre la Inteligencia Emocional y el Bienestar en estudiantes universitarios: Diferencias entre titulaciones

    Fraile Diego, Elena

    2014-01-01

    La presente investigación tiene como objetivo analizar la relación entre Inteligencia Emocional y Bienestar en una muestra del alumnado universitario compuesta por 168 participantes de cuatro titulaciones diferentes. Y analizar si existen diferencias en estas variables en función de la titulación y el sexo. Recogimos datos sociodemográficos y evaluamos: a) Inteligencia Emocional con la escala rasgo de metaconocimiento (TMMS-24), b) Bienestar y sus diferentes elementos con la escala de Bienest...

  5. SI Notes.

    Nelson, Robert A.

    1983-01-01

    Discusses legislation related to SI (International Systems of Units) in the United States. Indicates that although SI metric units have been officially recognized by law in the United States, U.S. Customary Units have never received a statutory basis. (JN)

  6. Pour un dialogue mondial entre traditions philosophiques

    Dussel, Enrique

    2013-01-01

    Nous allons essayer de réfléchir à un sujet qui, je crois, occupera une bonne partie du xxie siècle : l’acceptation par chacune des traditions régionales philosophiques de la planète (européenne, nord-américaine, chinoise, hindoue, arabe, africaine, latino-américaine, etc.) du sens, de la valeur et de l’histoire de chacune d’entre elles. Pour la première fois dans l’histoire de la philosophie, différentes traditions entameraient un dialogue authentique et symétrique grâce auquel elles découvr...

  7. Espectros biológicos florísticos de Campos Rupestres de afloramento e Campos Úmidos diferem entre si e em relação ao Espectro Biológico Normal de Raunkiaer. Floristic biological spectra of Rock outcrops and Wet grasslands differ between themselves and in relation to the Raunkiaer’s Normal Biological Spectrum.

    Natalia de Oliveira COSTA

    2012-12-01

    Full Text Available A distribuição de frequência de classes de formas de vida em uma flora, conhecida como espectro biológico florístico, varia em função das condições climáticas e edáficas em que as plantas se desenvolvem. Neste trabalho comparamos os espectros biológicos médios (n = 3 de equivalentes a Campo Rupestre de afloramento e a Campo Úmido no Estado de São Paulo na expectativa de encontrar diferenças significativas entre os dois tipos de comunidade. Os Campos Rupestres (G-corrigido = 23,41; p-valor = 0,0001 e os Campos Úmidos (G-corrigido = 80,34; p < 0,0001 diferiram do Espectro Biológico Normal de Raunkiaer, bem como diferenciaram-se entre si (χ2 = 24,23; p < 0,0001. Uma Análise de Correspondência Distendida separou Campos Rupestres de Campos Úmidos devido às maiores frequências de fanerófitos nos primeiros e de hemicriptófitos e terófitos nos últimos. Sugerimos como hipóteses que os micro-habitats favoráveis ao desenvolvimentode fanerófitos sejam mais comuns nos Campos Rupestres de afloramento do que nos Campos Úmidos, ocorrendo o contrário com os micro-habitats favoráveis aos hemicriptófitos. Esta forma de vida pode apresentar melhor ajustamento ao encharcamento do solo do que os caméfitos e geófitos. A estratégia de escape apresentada pelos terófitos seria pouco eficiente em Campos Rupestres de afloramento devido à escassez de solo para proteção das sementes. The frequency distribution of life forms in a flora, called floristic biological spectrum, varies according to the climatic and edaphic conditions under which plants grow. In this work we compared the average (n = 3 biological spectra of Rock outcrop and Wet grassland like communities in São Paulo state expecting to find significant differences between the two community types. Rock outcrops (G-corrected = 23.41; p-value = 0.0001 and Wet grasslands (G-corrected = 80.34; p < 0.0001 differed from the Raunkiaer’s Normal Biological Spectrum, as did between

  8. Generación de materia orgánica acoplada a la eliminación de CO2 por Anabaena sp. ATCC 33047 y su utilización para la remoción de cadmio

    Esteban Clares, Marta

    2011-01-01

    El incremento del nivel atmosférico de dióxido de carbono, gas de efecto invernadero, y la necesidad de reducir el mismo constituye un problema global de ingentes proporciones. Una aproximación a este problema consiste en la utilización de microorganismos fotosintéticos para la retirada del CO2. Microalgas y cianobacterias se encuentran entre los más efectivos fijadores de CO2 del planeta, con rendimientos considerablemente superiores a los de los cultivos agrícolas más productivos. En este t...

  9. Communication entre deux mondes: relations amicales entre sourds et entendants

    Favre, Cynthia; Pitarelli, Emilio

    2008-01-01

    Ce travail de recherche aborde la problématique de la surdité. Il souhaite étudier plus particulièrement les relations entre personnes sourdes et entendantes. Il permet de bousculer certaines fausses conceptions concernant les personnes sourdes et donne des informations au sujet de leur histoire, de leur mode de vie et de leur communauté. Cette recherche recense également les facteurs qui peuvent influencer la communication ainsi que les relations amicales entre les personnes sourdes et enten...

  10. ANÁLISIS DE RESIDUOS DE PLAGUICIDAS EN TOMATE MEDIANTE EL USO DE QuEChERS Y CROMATOGRAFÍA LÍQUIDA ULTRARRÁPIDA ACOPLADA A ESPECTROMETRÍA DE MASAS

    Diego A. Ahumada

    2011-12-01

    Full Text Available Se desarrolló un método multirresiduopara la determinación de 24 plaguicidasde diferentes características fisicoquímicasen tomate. El proceso de extracciónse basó en el método QuEChERS y la determinaciónde los compuestos se realizómediante cromatografía líquida ultrarrápidaacoplada a espectrometría de masas.Los resultados de la validación indicaronque el método presenta porcentajes derecuperación de entre el 71,3 y el 114%,coeficientes de variación inferiores al20%, límites de detección entre 0,002 y0,225 mg/kg, límites de cuantificaciónentre 0,009 y 0,750 mg/kg. En los estudiosde linealidad, para todos los parámetrosevaluados, se obtuvieron resultados adecuados en los rangos de trabajo. Paraprobar la metodología desarrollada, seevaluaron muestras de frutos de tomateprovenientes del departamento de Boyacáy se halló indoxacarb en cantidadesinferiores al límite máximo de residuos.

  11. El conflicto entre grupos profesionales

    Yubero, Santiago

    1999-01-01

    La dinámica de las relaciones entre los grupos es la esencia de la vida social e, incluso, hay quienes piensan que no son las relaciones entre los grupos, sino los conflictos que se producen en ei marco de las relaciones grupaies los que nos dan las claves de la propia dinámica social. En este sentido, no es descabellado pensar que los conflictos grupaies aportan la energía necesaria para que tanto las organizaciones, como la propia sociedad muestren su actividad en...

  12. Resultados - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Quinto vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  13. ????????????-???????????? ?????? ? ????????????? ????????? ???????? ??????? Ge-Si

    ????????, ?. ?.; ???????????, ?. ?.; ???, ?. ?.; ?????????, ?. ?.

    2003-01-01

    ?????????? ????????????-???????????? ?????? ? ????????????? ????????? (??) ???????? ??????? GexSi1-x (? = 0.01 - 0.03) p-???? ??????????? ? ?????????????? ????????? (4,2 ... 300 K). ????????????? ????? ?????????? ?? ?????-??? ?? ?????????????????? ??. ??????????? ?????????? ??????? ????????? ??????? ??? ?????????? ??. ???????? ?????????? ??????????? ?'???-??????? ?? ??????????????? ? ?? Ge-Si ??????? ???????? ?????-?????????? ?? ???????? ???????????. ?????????? ?????????? ??????????? ???...

  14. Relación entre Inteligencia Emocional y rendimiento escolar

    Vicente-Pérez, Minerva

    2014-01-01

    Actualmente, la Inteligencia Emocional es un tema de plena actualidad, y es creciente el número de estudios que se publican al respecto. Su influencia en los procesos de enseñanza-aprendizaje y su importancia en el entorno escolar son bien conocidas, sin embargo, aún resulta necesario indagar en el papel de las emociones en el rendimiento académico de los alumnos. El presente estudio trata de comprobar si existe relación entre la Inteligencia Emocional y el rendimiento académico en los alu...

  15. Identificação de compostos orgânicos e farmacêuticos em esgoto hospitalar utilizando cromatografia gasosa acoplada a espectrometria de massa Identification of organic and pharmaceutical compositions in hospital wastewater using a gas chromatograph coupled to mass spectrometry

    Francisco Vieira Paiva

    2011-03-01

    Full Text Available Os resíduos líquidos provenientes dos estabelecimentos assistenciais de saúde são mais complexos do que os esgotos domésticos. Sua composição contém inúmeros compostos farmacêuticos, saneantes, elementos radiativos e de laboratórios. O conhecimento desses compostos pode auxiliar na escolha do tratamento adequado para esses esgotos e diminuir os impactos ambientais nos corpos receptores. A pesquisa foi realizada utilizando um sistema combinado (UASB e lodos ativados para tratar a água residuária de um hospital. Neste trabalho, foram realizadas análises físico-químicas para caracterização do esgoto e cromatografia gasosa acoplada à espectrometria de massa para identificação de compostos químicos farmacêuticos, podendo-se constatar a presença de inúmeros elementos residuais dos fármacos usados no hospital.Liquid waste residues from health care establishments are more complex than those from residential sewage. Their composition contains several pharmaceutical chemical composites, sanitizers, radioactive, and laboratorial elements. Knowing about these composites may aid in choosing the proper treatment for these sewages, and diminish the environmental impact in receptors. The study was carried out in a combined system (UASB and activated sludge to treat a hospital wastewater. In this experiment, material and chemical analyses were employed to trace sewage characteristics and gas chromatography associated with mass spectrometry to identify pharmacologic chemical composites, where innumerous residual elements were found in chromatographs.

  16. Application of the SPA in the design of a hydrogen producer plant coupled to a nuclear reactor; Aplicacion del APS en el diseno de una planta productora de hidrogeno acoplada a un reactor nuclear

    Ruiz S, T.; Nelson, P. F.; Francois, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac No. 8532, Col. Progreso, 62550 Jiutepec, Morelos (Mexico); Cruz G, M. J., E-mail: truizsmx@yahoo.com.mx [UNAM, Facultad de Quimica, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2013-10-15

    At the present time, one of the processes that is broadly investigated and that, theoretically demonstrates to be one of the most efficient for the hydrogen production, is the thermal-chemistry cycle Sulfur-Iodine (S-I) coupled to a nuclear reactor of very high temperature (VHTR). Because this chemical process of hydrogen production requires of a great inventory of toxic materials (sulphide compounds, hydriodic acid and iodine), is necessary the design of emergency systems with the purpose of protecting the facilities and the equipment s, the environment, as well as the near population. Given the impact of an accidental liberation of the process materials, as well as the proximity with the nuclear plant, is necessary that these emergency systems are the most reliable possible. This way, the results of the consequences analysis are utilized for the optimal localization of the gas sensors that activate the emergency systems, and the flows of the substances that are used for the leakage control. For all this, the use of the Safety Probabilistic Analysis methodology, as well as some standards of the nuclear industry, can be applied to the chemical installation to determine the fault sequences that can take to final states of not controlled leakage. This way, the use of methodologies of Event Tree Analysis and Fault Trees show in their results the components that but contribute in fault of such systems. In this work, is presented the evaluation of the joined models of event and fault trees and like with the obtained results, some proposals to increase the safety of the facilities are exposed. Also, the results of the evaluations of these proposals, and their impact of the probability of the not controlled fault sequences in a plant that is still in design stage are showed. (Author)

  17. La Vocación entre los Aspirantes a Maestro

    Encarnación Sánchez Lissen

    2003-01-01

    Full Text Available El contenido que ofrecemos en este artículo hace referencia a la dimensión vocacional de los aspirantes a maestro. Tradicionalmente, la enseñanza se ha considerado como una profesión genuinamente vocacional; una circunstancia que, sin embargo, no siempre le ha favorecido. En estos momentos, a pesar de las dificultades que rodean la tarea docente, existe un alto número de estudian-tes que optan por la enseñanza y acceden a las Escuelas de Magisterio. Real-mente, nos podríamos preguntar si el docente -nace o se hace- vocacional hacia esta actividad profesional. Aportamos para ello, los datos de una investigación realizada entre estu-diantes de la Universidad de Sevilla, donde se viene a demostrar por un lado que, muchos eligieron la carrera sin tener un verdadero interés por ella; y por otro, que las Escuelas de Magisterio son en muchos casos, un motor esencial para llegar a despertar o, a descubrir entre los estudiantes, su verdadero interés e inclinación por la enseñanza. Posiblemente, desarrollar actitudes vocaciona-les entre tos aspirantes a maestro es, también, una labor implícita de la Forma-ción Inicial de Maestros

  18. Causalidade entre as principais bolsas de valores do mundo

    Hiron Pereira Farias

    2010-04-01

    Full Text Available O objetivo deste trabalho foi analisar os mercados dos países emergentes que fazem parte do Bric, com exceção da Índia, buscando mostrar como os mercados do Brasil, da Rússia e China se comportam entre si e em relação ao mercado dos Estados Unidos. Analisou-se também como alguns países desenvolvidos do grupo G8, Estados Unidos, Reino Unido e Japão, se comportam. Em cada análise, ajustou-se um modelo VAR e buscou-se verificar o grau de dependência dentro e entre cada grupo, utilizando teste de causalidade de Granger, critérios de seleção de modelos, função resposta a impulso e decomposição da variância do erro de previsão. Nas análises realizadas, os mercados brasileiro e americano mostraram forte influência sobre os demais mercados, e, na análise entre os grupos, consideraram-se o mercado dos Estados Unidos do grupo ERJ e todos os mercados emergentes do grupo BRC. O mercado americano mostrou forte influência sobre os outros mercados.

  19. La telecolaboración entre grupos heterogéneos en la clase de lengua extranjera

    López Santiago, Mercedes; Ballez, Michèle

    2014-01-01

    En la enseñanza de lenguas extranjeras, numerosos profesores trabajan las competencias lingüísticas y comunicativas por medio de actividades que incluyen las TIC. Entre ellas, se encuentran los proyectos de telecolaboración por Internet, intercambios asincrónicos y sincrónicos entre grupos de estudiantes pertenecientes a diferentes comunidades  lingüísticas distantes geográficamente. Nuestro objetivo ha consistido en comprobar si un proyecto de telecolaboración sincrónico entre grupos heterog...

  20. La telecolaboración entre grupos heterogéneos en la clase de lengua extranjera

    López Santiago, Mercedes; Ballez, Michèle

    2014-01-01

    [es] En la enseñanza de lenguas extranjeras, numerosos profesores trabajan las competencias lingüísticas y comunicativas por medio de actividades que incluyen las TIC. Entre ellas, se encuentran los proyectos de telecolaboración por Internet, intercambios asincrónicos y sincrónicos, entre grupos de estudiantes pertenecientes a diferentes comunidades lingüísticas distantes geográficamente. Nuestro objetivo ha consistido en comprobar si un proyecto de telecolaboración sincrónico entre grupos he...

  1. Entre viajantes, invernos e cidades: duas obras de Italo Calvino

    Rebecca Pedroso Monteiro

    2015-04-01

    Full Text Available Esse ensaio pretende realizar uma leitura comparada entre duas obras de Calvino, As cidades invisíveis e Se um viajante numa noite de inverno, observando como se configuram os movimentos de interrupção e transbordamento ali presentes. O recurso do “cancelamento sucessivo” em Se um viajante numa noite de inverno (cujo limite é o “cancelamento do mundo” pode operar como um “falso duplo” dos desdobramentos sucessivos de As cidades invisíveis, em sua complexa alegorização a partir de territórios tão infinitos quanto a memória, o desejo, os símbolos, as trocas, os mortos e o céu. Se de um lado (o do “viajante” temos cortes sucessivos e abruptos que se desdobram em sempre novas operações decisórias e respectivos cortes, como o próprio Calvino reconheceu, de outro (o do “espaço percorrido pelo viajante” temos um único tema (a cidade dobrando-se sobre si mesmo em progressão (quase geométrica. Entre um movimento e outro, o “catálogo indicativo das atitudes existenciais que conduzem a outros tantos caminhos obstruídos” sugerido pelo autor se mostra como um horizonte de desejo impossível, como uma engenhosa metáfora para algo que está entre o movimento do viajante e a imobilidade da paisagem, entre o corte e a multiplicação, entre o que sempre muda e o que nunca se movimenta. O intervalo liminar que todos esses recursos encenam e simbolizam é multiplicado (ou encerrado? na trama de faltas e excessos que é potencializada por cada um dos livros, fazendo da experiência do indizível e da intraduzibilidade da experiência a força narrativa e poética dessas duas obras, e de tudo o que pode ser tecido entre elas.

  2. A importância das interacções entre fungos do solo em agroecologia

    Baptista, P; Pereira, Eric; Tavares, R. M.; Neto, T. Lino

    2011-01-01

    Os microrganismos vivem no solo sob a forma de comunidades complexas, sendo constantes as interacções que estabelecem entre si e com as raízes das plantas. Esta enorme diversidade de interacções contribui, de forma preponderante, para a fertilidade do solo, desenvolvimento, nutrição e sanidade das plantas. Ao nível da comunidade fúngica do solo é possível observar vários tipos de interacção entre diferentes espécies fúngicas, sendo o antagonismo um dos mais comuns. Os fungos do solo são igual...

  3. Relación entre habilidades de lectura de palabras y comprensión lectora

    Vieiro, Pilar; Amboage, Isabel

    2016-01-01

    La lectura es un aprendizaje instrumental que debe ser enseñado con un método específico. En este sentido es importante conocer la interrelación entre los distintos subprocesos implicados. En este contexto el objetivo general de este estudio es analizar si existe una asociación o disociación entre las habilidades de lectura de palabras y los procesos de comprensión en alumnos de 2º ciclo de Educación Primaria y a partir de aquí analizar las implicaciones educativas de los resultad...

  4. Travesías entre la investigación y la docencia

    José Canziani

    2012-01-01

    En este artículo, hago un breve recuento de mi experiencia docente, especialmente en la PUCP. Una experiencia que creo transita entre la permanente inquietud interdisciplinaria, en la que se entremezclan la Arquitectura y el Urbanismo, la Arqueología, la Antropología, los estudios territoriales y algo de Geografía; y, por otra parte, una experiencia que transita entre el mundo de la investigación y de la docencia, entendidas como dos aspectos inseparables, quizás indisolubles si los entiendo ...

  5. La retractación arbitraria, entre principios y remedios

    Matteo Dellacasa

    2012-06-01

    Full Text Available En la jurisprudencia italiana se ha consolidado el enfoque según la cual el juez está legitimado para controlar el ejercicio del derecho de retractación discrecional. Ante una solicitud expresa de la parte, el juez, incluso, está obligado a verificar la conformidad de la conducta de quien ejerce el derecho con el canon de la buena fe contractual. La reflexión de la doctrina italiana se concentra prevalentemente en la dialéctica entre autonomía privada y control judicial, mientras es menos frecuentado el terreno de los remedios que siguen a la retractación arbitraria. En este segundo perfil se concentra el presente escrito. En primer lugar, se afirma que el control jurisdiccional de la retractación ad nutum es oportuno en relación con todos los contratos, y no solo en aquellos caracterizados por la asimetría de poderes entre las partes. El remedio generalmente aplicable a favor de la parte que sufre la retractación arbitraria se identifica con el resarcimiento del interés negativo: el contratante desilusionado puede obtener el reembolso de los gastos asumidos y el resarcimiento de las oportunidades de ganancias perdidas como consecuencia de la confianza depositada en la realización del negocio. En segundo lugar, se delinean los criterios que permiten identificar la retractación arbitraria. En fin, se analiza si la existencia de una relación de dependencia económica entre la empresa que se retracta arbitrariamente y su contraparte contractual puede justificar la aplicación de un remedio diferente del resarcimiento del interés negativo. El autor está orientado a responder afirmativamente. Si la empresa que sufre la retractación ilegítima ha realizado inversiones específicas –centradas en las exigencias de la contraparte y, por esto, difícilmente recuperables–, el resarcimiento del interés negativo ofrece una tutela parcial e inadecuada. Los remedios aplicables, en cambio, deben salvaguardar el interés positivo de la

  6. Interrelaciones entre caries y sobrepeso en una población infantil

    Sanjurjo Trigueros, Silvia

    2013-01-01

    La caries y el sobrepeso son enfermedades de etiología multifactorial, con un factor común, la dieta. Nos planteamos si los escolares que padecen sobrepeso u obesidad presentan más caries que los escolares con peso adecuado, es decir, si existe una relación entre la caries dental y el sobrepeso u obesidad. Además, consideramos que los escolares con sobrepeso u obesidad pueden tener una mayor frecuencia en la ingesta y un consumo más elevado de alimentos azucarados, pudiendo tener una ma...

  7. O conhecimento de si como possibilidade para a transformação de si e do coletivo

    Rosemary Silva da Silveira

    1999-12-01

    Full Text Available Para promover a discussão e reflexão em grupo sobre o significado do trabalho da enfermagem numa unidade cirúrgica e diante da constatação da necessidade dos trabalhadores de enfermagem conhecerem-se mais a si e entre si, como participantes e construtores de um trabalho coletivo, implementou-se uma prática, entendida como uma tecnologia do eu, que favorecesse o conhecimento de si e do outro na tentativa de transformar a si e, conseqüentemente, o coletivo. A partir da exposição verbal e individual, ao grupo, da percepção de si, propôs-se o registro escrito de qualidades e conselhos que poderiam ser atribuídos a cada membro da equipe de enfermagem. Sistematizadas as contribuições, cada participante recebeu, individualmente, o conjunto de percepções do grupo sobre si. Tais estratégias constituíram-se em espaços mobilizadores para o diálogo, a reflexão crítica e uma maior aproximação entre os trabalhadores, representando uma possibilidade de cuidado de si e de aperfeiçoamento pessoal e grupal.

  8. PROEJA: ENTRE DESAFIOS E POSSIBILIDADES

    D. H. Moura

    2012-05-01

    Full Text Available Neste trabalho, pesquisa-se a gênese e os anos iniciais de vigência do Programa de Integração da Educação Profissional à Educação Básica na Modalidade Educação de Jovens e Adultos – PROEJA – que visa oferecer oportunidades educacionais que integrem, na modalidade educação de jovens e adultos, o ensino médio à educação profissional técnica de nível médio ou o ensino fundamental à formação inicial e continuada de trabalhadores. Por meio de revisão bibliográfica e análise de documentos, analisa-se o Programa, enfocando os equívocos em sua implantação, suas possibilidades e desafios. Vale salientar que apesar de o PROEJA abranger a integração da educação profissional à educação básica, neste trabalho, a análise está concentrada na integração entre os cursos técnicos de nível médio e o ensino médio.

  9. Burnout e intenciones de jubilación anticipada entre empleados mayores - Burnout and early retirement intentions among older employees

    Henkens, C.J.I.M.; Leenders, M.

    2009-01-01

    El tema central de este artículo es la jubilación y el burnout de los empleados mayores. Analizamos si existe una relación entre las dimensiones de agotamiento emocional y despersonalización características del burnout y las intenciones de jubilación de los empleados mayores. Asimismo, se investiga

  10. CORRELATOS ENTRE BIENESTAR SUBJETIVO Y REGULACIÓN EMOCIONAL DEL ENOJO: DIFERENCIAS POR SEXO

    Magali Martínez Pérez; Rozzana Sánchez Aragón

    2014-01-01

    Las experiencias emocionales negativas se asocian con el bienestar subjetivo, pero se ignora si la manera de regularlas se relaciona con los reportes de bienestar. El presente estudio exploró la asociación entre el bienestar percibido y ciertas variables culturales (premisas histórico-socio-culturales) e individuales (automonitoreo, estrategias y autoeficacia) involucradas en la regulación del en ojo, así como las posibles diferencias sexuales. Participaron 220 residentes que respondieron vol...

  11. Propuesta de comunicación entre un ambiente inmersivo y el mundo real

    Garcia, Jose Manuel; Sutz, Guillermo; Monti, Hernan; Sattolo, Iris; Lipera, Liliana; Romero, Juan Carlos; Benito, Patricia

    2015-01-01

    En este trabajo de investigación, se planteó la utilización de los mundos virtuales inmersivos a la Educación a distancia, usando el aplicativo opensouce: OpenSim. Si bien las plataformas existentes ofrecen comunicación bidirecccional entre el alumno y el profesor, estas no son en tiempo real. Para achicar esta brecha es que se presenta esta propuesta.

  12. Relación entre la Enfermedad Periodontal y Parto Prematuro

    Quevedo García, Rodrigo

    2013-01-01

    Entender la posible relación entre una enfermedad infecciosa local muchas veces subliminar como la enfermedad periodontal y una de las complicaciones más frecuentes del embarazo como es el parto prematuro. También se intentan describir los mecanismos de esta interacción y si el tratamiento de la EP reduce el PP. Finalmente resaltar la importancia de la salud oral y especialmente periodontal en la salud istémica del individuo.

  13. Ordering at Si(111)/o-Si and Si(111)/SiO2 Interfaces

    Robinson, I. K.; Waskiewicz, W. K.; Tung, R. T.;

    1986-01-01

    X-ray diffraction has been used to measure the intensity profile of the two-dimensional rods of scattering from a single interface buried inside a bulk material. In both Si(111)/a-Si and Si(111)/SiO2 examples there are features in the perpendicular-momentum-transfer dependence which are not expec...... are not expected from an ideal sharp interface. The diffraction profiles are explained by models with partially ordered layers extending into the amorphous region. In the Si(111)/a-Si case there is clear evidence of stacking faults which are attributed to residual 7×7 reconstruction....

  14. La telecol.laboració en la classe de llengua extranjera entre grups heterogenis d’estudiants

    Mercedes López Santiago

    2014-06-01

    Full Text Available En l'ensenyament de llengües estrangeres, nombrosos professors treballen les competències lingüístiques i comunicatives mitjançant d'activitats que inclouen les TIC. Entre algunes, es troben els projectes de telecol·laboració per Internet, intercanvis asincrònics i sincrònics entre grups d'estudiants que pertanyen a diferents comunitats lingüístiques allunyades geogràficament. El nostre objectiu ha consistit a comprovar si un projecte de telecol·laboració sincrònic entre grups heterogenis d'estudiants, és factible i si contribueix al desenvolupament de les competències comunicatives, interculturals i tecnològiques.

  15. Mohasseb Saliba Sabine, Les monastères maronites doubles du Liban, Entre Rome et l’Empire ottoman (xviie– xixe siècles, préface d’Henry Laurens, Paris, Geuthner et Kaslik, Presses de l’université Saint-Esprit de Kaslik (PUSEK 2008, 556 p.

    Gérard D. Khoury

    2011-12-01

    Full Text Available Ce livre reprend l’essentiel d’une thèse que Sabine Mohasseb Saliba a soutenue sous la direction de Randi Deguilhem à Aix-en-Provence, intitulée « Monastères doubles, familles, propriétés et pouvoirs au Mont Liban : l’itinéraire du couvent maronite de Mar Challita Mouqbès (xviie- xixe siècles. Transformer un travail de thèse en un ouvrage offert à un public plus vaste que celui des chercheurs est une entreprise risquée. Sabine Mohasseb Saliba a réussi, grâce à un style clair et précis, à so...

  16. Le ballet pantomime et l'Antiquité : quelques notes de réflexion : Le recours à l'Antiquité dans le ballet d'action au XVIII siècle: Sources et modèles entre reconstruction, interprétation et création.

    Fabbricatore, Arianna

    2014-01-01

    Dans son processus de légitimation, le nouveau genre de danse théâtrale tente de trouver ses fondements théoriques dans l'Antiquité : le retour à la tradition antique, c'est-à-dire la recherche d'un modèle à imiter, apparaît comme une stratégie de justification du nouveau genre. Cependant ce retour à la tradition n'est pas sans ambigüité. Si les maîtres de ballets nourrissent l'aspiration à un modèle qui peut fournir au ballet d'action la légitimité recherchée, ils n'ignorent pas que ce modèl...

  17. Diferencias entre homosexuales y heterosexuales en comportamiento y personalidad

    Mirta Granero

    1984-01-01

    Full Text Available La autora informa de los resultados de 120 sujetos (30 varones heterosexuales, 30 varones homosexuales, 30 mujeres heterosexuales y 30 mujeres homosexuales, a los que se aplicaron cuestionarios y tests para averiguar comportamientos y rasgos de personalidad. Para el análisis de cada rasgo o comportamiento, los datos fueron clasificados por dos variables: Orientación sexual y Sexo. Se encontraron algunas diferencias significativas entre homosexuales y heterosexuales, como así también entre varones y mujeres, independientes de su orientación sexual. Se cuestiona si algunos tests tienen validez para algunos de estos grupos. Se piensa que puede haber respuestas determinadas por la presión social en la que vive el homosexual, en vez de por la variable que se supone que mide en él. Este primer informe, es parte de un trabajo más ambicioso, que la autora está realizando en la ciudad de Rosario (Argentina

  18. Evaluation of the security of a hydrogen producing plant by means of the S I cycle coupled to a nuclear reactor of high temperature; Evaluacion de la seguridad de una planta productora de hidrogeno mediante el ciclo SI acoplada a un reactor nuclear de alta temperatura

    Ruiz S, T.; Francois, J. L.; Nelson, P. F. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac No. 8532, Col. Progreso, 62550 Jiutepec, Morelos (Mexico); Cruz G, M. J., E-mail: truizsmx@yahoo.com.mx [UNAM, Facultad de Quimica, Ciudad Universitaria, 04510 Mexico D. F. (MX)

    2011-11-15

    At the present one of the processes that demonstrates, theoretically, to be one of the most efficient for the hydrogen production is the thermal-chemistry cycle Sulfur-Iodine. One way of obtaining the temperature ranges required by the process is through the helium coming from a very high temperature reactor. The coupling of the chemical plant with the nuclear plant presents aspects of security that should be analyzed; among them the analysis of the danger of the process materials is, with the purpose of implementing security measures to protect the facilities and equipment s, the environment and the population. These measures can be: emergency answer plans of the stations, definition of the minimum distance required among facilities, determination of the exclusion area, etc. In this study simulations were made with the computer code Phast in order to knowing the possible affectation areas due to the liberation of a great quantity of energy due to a helium leak to very high temperature, of toxic materials or by a possible hydrogen combustion. The results for the liberations of sulfuric acid, hydrogen, iodine, helium and sulfur dioxide are shown, specially. The operation conditions were taken of a combination of the preliminary design proposed by General Atomics and the optimized conditions by the Korea Advanced Institute of Science and Technology, considering a production of 1 kg-mol/s of hydrogen. The iodine was the material that presented a major affectation area. (Author)

  19. Como si fuera posible recoger sentimientos

    Vayreda Puigvert, Marian; Vallès Villanueva, Joan

    2011-01-01

    Se trata de una propuesta como resultado del trabajo conjunto entre la escuela de Arte Pigment y el ESPAI ZERO1 del Museu Comarcal de la Garrotxa, destinado exclusivamente a exposiciones temporales de creación contemporánea y como continuidad de propuestas anteriores de colaboración: REPLICA23 y SONESNAT JUNIOR. Com si fos possible recollir el sofriment es un proyecto de la artista Anna Manel.la, y se consideró una propuesta interesante y un reto para conversar, intercambiar y crear con los a...

  20. La frontière entre le bilād al-islām et le bilād al-Nūba : enjeux et ambiguïtés d’une frontière immobile (VIIe-XIIe siècle The frontier between bilād al-islām and bilād al-Nūba: issues and ambiguities of fixed boundary (seventh-twelfth century

    Robin Seignobos

    2011-03-01

    Full Text Available Le bilād al-Nūba occupe dans la nomenclature juridique et idéologique arabo-musulmane une position particulière. L’échec de la conquête de la Nubie au viie siècle a débouché sur la signature d’un traité de paix unique qui a fait de cet espace un territoire à part. Ces spécificités ne resteront pas sans effet sur l’appréhension de la frontière qui sépare les pays d’Islam de la Nubie. S’efforçant de définir la limite du bilād al-islām, les géographes arabes semblent unanimes à désigner Assouan comme la dernière ville frontière de l’islam chargée de défendre l’Égypte de l’ennemi latent que demeure, malgré la paix, le pays des Nubiens. Néanmoins, en examinant plus attentivement ces témoignages, ce dispositif frontalier se révèle en réalité plus complexe. Il se structure autour d���un élément naturel, la première cataracte, qui, loin de constituer la barrière infranchissable que certains de ces auteurs souhaiteraient y voir, forme plutôt un espace de transition entre ces deux mondes. Or, c’est justement en tirant parti des porosités de cette frontière que l’islam parvient, sans que cette démarcation soit véritablement remise en question, à étendre son influence bien au-delà de celle-ci.Bilād al-Nūbaholds a special place in the Arab-Islamic juridical and ideological nomenclature. As a consequence of the failure to conquer Nubia in the 7th century, a peace treaty was signed that singled out this territory. These specificities were not devoid of consequences on the perception of the frontier between Islamic countries and Nubia. When delimiting bilād al-islām, Arabic geographers unanimously agreed in designating Aswan as the last frontier-town of Islam, in charge of defending Egyptian territory from potential Nubian enemies.A closer examination of the sources brings to light the unexpected complexity of this frontier system. It was apparently shaped around a geographical

  1. Determinação de esteróides androgênicos anabólicos em urina por cromatografia gasosa acoplada à espectrometria de massas Detection of androgenic anabolic steroids (AAS in urine samples by gas chromatography-mass spectrometry

    Daniel Rossi de Campos

    2005-12-01

    Full Text Available Esteróides androgênicos anabólicos (EAA são substâncias naturais, sintéticas ou semi-sintéticas derivadas da testosterona, utilizadas em atividades esportivas com o objetivo de melhorar o desempenho físico pelo aumento de massa e força muscular. Apesar de causarem efeitos tóxicos graves, principalmente sobre os sistemas cardiovascular, hepático e neuro-endócrino, os EAA têm sido amplamente utilizados no âmbito esportivo. Desta forma, o presente trabalho teve como objetivo a validação de um método para a determinação de esteróides e/ou seus produtos de biotransformação em amostras de urina por cromatografia gasosa acoplada à espectrometria de massas (CG-EM. O método baseou-se na hidrólise enzimática de esteróides conjugados, no emprego da extração líquido-líquido e na derivação do extrato para posterior análise por CG-EM, no modo de monitoramento seletivo de íons (SIM. O método validado cumpriu com os princípios de confiança necessários para a determinação de EAA em amostras de urina com a finalidade de controle de dopagem no esporte. Os limites de detecção dos esteróides analizados variaram de 0,5 a 15 ng/mL. Bons valores de precisão (intra e interensaio também foram obtidos (CVAndrogenic anabolic steroids (AAS are defined as natural, synthetic or semi-synthetic drugs chemically derived from testosterone, used with the aim to improve physical performance by increasing both muscle strength and mass. Despite their reported toxicological effects on the cardiovascular, hepatic and neuro-endocrine systems, the AAS have been extensively used in sports activities. The objective of this study was to validate an analytical method for the detection of AAS and/or their metabolites in urine samples. The method was based on enzymatic hydrolysis, liquid-liquid extraction, derivatization and further analysis by gas chromatography-mass spectrometry (GC-MS operated in the selected ion monitoring mode (SIM. The

  2. Patpong, entre sexe et commerce.

    Sébastien Roux

    2010-03-01

    Full Text Available Le tourisme dit « sexuel » est aujourd’hui décrié comme une forme de tourisme international immoral, un dysfonctionnement grave de la mondialisation appelant une réaction politique contre « l’exploitation sexuelle » dont seraient victimes des millions de femmes et d’enfants. Pourtant, derrière l’apparente évidence du « tourisme sexuel » comme expression de sens commun, rares sont les enquêtes qui explicitent la réalité concrète des échanges prostitutionnels. En adoptant une démarche ethnographique, l’article décrit le fonctionnement de Patpong, un quartier rouge de Bangkok dédié à une clientèle internationale. Par la description des offres disponibles, des revenus générés, des codes et des pratiques, la complexité de l’espace réapparaît. Il s’agit de donner à voir la réalité des échanges pour interroger l’articulation entre commerce et sexualité. L’analyse ethnographique du tourisme sexuel permet ainsi de souligner la diversité des pratiques et de rappeler que les formes les plus visibles — et les plus commentées — d’échanges prostitutionnels éclipsent trop souvent une pluralité d’expériences qui participe pourtant au succès de ces ruelles mondialement connues. So-called sex tourism is condemned as an immoral form of international tourism, a serious failure of globalization requiring political action against the “sexual exploitation” suffered by millions of women and children. Yet behind the common and seemingly evident understanding of “sexual tourism,” few studies have focused on the actual reality of such relations. Based on an ethnographic study, this article presents the structure of Patpong, a red-light district of Bangkok dedicated to international tourism. First, the article aims to briefly present the historical development of Patpong. This peculiar space is intrinsically linked to sex tourism, as these world-renowned streets expanded since the mid-60s to

  3. Práticas educativas entre crianças e adultos: encontros e desencontros

    Elaine de Paula

    2010-10-01

    O presente texto examina as práticas educativas desenvolvidas em uma instituição de educação infantil pública com o intuito de analisar as relações estabelecidas entre os adultos e as crianças no interior da instituição e também as relações que as crianças estabeleciam entre si (relações entre pares no sentido de perceber as múltiplas estratégias criadas pelas crianças no complexo processo de acomodação, resistência e reinvenção que desenvolvem como forma de atender aos desejos e interesses que possuem. Para dar visibilidade a tais manifestações utilizamos diferentes recursos metodológicos: registros escrito, fonográfico e fotográfico; dramatizações, narração de histórias, produção de desenhos e observação. Os jeitos de agir das crianças indicam-nos um aprendizado social de como lidar com as estruturas impostas e reforça a idéia de redes de aprendizagem construídas no sentido horizontal- entre pares- e vertical- entre Adultos e crianças. A importância de buscar conhecer o que as crianças sentem, pensam e desejam advém de uma perspectiva teórica que considera as crianças como sujeitos sociais competentes para dizer de si mesmos. Perspectiva que considera a ação humana e a alteridade como fatores fundamentais para a construção de relações autônomas que respeitem as diferenças sem deixar de combater as desigualdades sociais.

  4. L’effet de présence : entre image fixe et image animée, les représentations de la Passion (fin XIXe-début XXe siècle In search of presence: Representations of the Passion between the fixed and moving image (late 19th, early 20th century

    Isabelle Saint-Martin

    2008-06-01

    Full Text Available Les représentations de la Passion et de la Vie de Jésus ont figuré parmi les premiers titres des débuts du cinéma. A posteriori, la critique des films religieux, notamment dans les années soixante, a été sévère pour ces tentatives jugées plus commerciales que très inspirées. L’intérêt pour le cinéma des premiers temps s’est approfondi dans les dernières décennies et favorise une autre approche de ces productions des années 1895-1920. Restituer l’univers visuel dans lequel ces films ont pris naissance permet de préciser les modalités de représentation des sujets biblique, en lien avec l’historicisme et l’orientalisme. Outre les liens étroits avec la peinture et la photographie, ces premiers films retrouvent certains effets narratifs des jeux de la Passion ou des projections d’images fixes encore abondantes au tournant du XXe siècle. S’attacher à la conception de la figuration contribue à cerner le « désir de voir » et l’effet de présence christique qui se manifestent dans ces premières Passion filmées.Representations of the Passion and the Life of Jesus Christ were a popular topic in early cinema. Retrospective criticism, especially in the 1960’s, was judgmental towards the first religious films, insofar as they were regarded more as commercially driven reenactments than inspired works. Interest in early cinema deepened in recent decades, and has led to a different reading of productions from the period 1895-1920. By restoring the universe of visual references in which these films arose, we are able to relate representations of biblical subjects to movements in historicism and Orientalism. Beyond their close relationship with painting and photography, these early films also reproduced the narrative effects of Passion plays or projections of fixed images that were still widespread at the turn of the 20th century. A focus on figurative conception will help us reconnect with the "need to see" and

  5. Estudio descriptivo y comparativo entre padres y madres que participan en un programa de prevención sobre consumo de drogas y conductas de riesgo

    Vilaregut Puigdesens, Anna; Mateu Martínez, Clara; Virgili Tejedor, Carles; Rusiñol Estragués, Jordi; Estrada Ocón, Maria; Cabra Soler, Quim

    2012-01-01

    Objetivos: describir y analizar las competencias o habilidades parentales que tienen los padres y las madres que acuden a un programa de prevención sobre el consumo de drogas y otras conductas de riesgo, comprobar si existen diferencias entre los padres y las madres en referencia al rol parental y, por último, conocer si existen diferencias entre el rol parental y el nivel de escolarización de los hijos. Método: la muestra estuvo formada de 89 participantes (22 padres y 67 madr...

  6. Asociación entre hipertensión arterial y el exceso de peso en niños y adolescentes entre los 8 y 18 años de colegios de Bogotá

    González Huérfano, María Alejandra

    2015-01-01

    La epidemia global de obesidad se ha visto relacionada con el aumento de la prevalencia de hipertensión arterial en la edad pediátrica. Objetivo: Determinar la frecuencia de hipertensión arterial y obesidad en niños y adolescentes de Bogotá y establecer si existe asociación entre hipertensión arterial y el exceso de peso. Metodología: Estudio descriptivo transversal que incluyó 270 niños y adolescentes entre 8 y 18 años de dos colegio de Bogotá. Se obtuvo información sobre edad, peso, t...

  7. "El retablo de Maese Pedro" de Manuel de Falla: un diálogo entre música, literatura y política

    Sevilla Llisterri, Inés

    2015-01-01

    En este trabajo hemos desarrollado el análisis de la ópera "El retablo de maese Pedro" (1923) de Manuel de Falla como lectura del "Quijote" (1605 y 1615) de Cervantes, desde las relaciones que establece el compositor entre música, literatura y política. Se trata, por tanto, de un estudio comparado entre ambas obras, si bien centrado en definir el diálogo que establece el compositor con Miguel de Cervantes. El título de esta tesis doctoral habla de "diálogo" entre música, literatura y polí...

  8. Correlações entre caracteres quantitativos em milho pipoca Correlation among quantitative traits in popcorn maize

    Valéria Carpentieri-Pípolo; Hideaki Wilson Takahashi; Romeu Munashi Endo; Marcos Rafael Petek; Adilson Luiz Seifert

    2002-01-01

    Em um programa de melhoramento, o conhecimento da grandeza das associações entre caracteres de interesse, é de fundamental importância na obtenção de populações melhoradas. O presente trabalho teve como objetivo determinar as correlações genotípicas, fenotípicas e ambientais entre caracteres quantitativos em milho pipoca. Foram avaliados nove genótipos de milho pipoca dispostos no campo em delineamento em blocos casualizados com oito repetições. Os genótipos UEL ZP, UEL SI e UEL PAP revelaram...

  9. Escritura de resultados - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Sexto vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  10. RELACIÓN ENTRE LOS NIVELES DE AUTOESTIMA Y ESTRÉS EN ESTUDIANTES UNIVERSITARIOS

    Leticia Ancer Elizondo; Cecilia Meza Peña; Edith G. Pompa Guajardo; Francisco Torres Guerrero; René Landero Hernández

    2011-01-01

    El presente estudio exploró la relación entre el estrés y la autoestima en 219 jóvenes de una universidad privada del área metropolitana de Monterrey (México), además de determinar si hay diferencias por género y por estatus laboral. Se utilizó la Escala de Estrés Percibido de Cohen y la Escala de Autoestima de Rosenberg, ambas en formato electrónico. Los resultados obtenidos indican la presencia de una correlación negativa entre estrés y autoestima, incrementándose en los jóvenes que solamen...

  11. El desplazamiento de la responsabilidad como variable mediadora entre la anomia y el copiarse en los exámenes

    Sánchez Medina, Agustín; Ramos Montesdeoca, Mónica; Blázquez Santana, Félix

    2014-01-01

    [ES]Determinar los motivos que hacen que los estudiantes se copien resulta de especial interés si se tiene en cuanta el alto porcentaje de copia que existe actualmente. En este trabajo concretamente se analizará cómo un determinado estado de ánimo negativo, como es la anomia, influye en la acción de copiar. Además, se estudiará si un mecanismo de desenganche moral, el desplazamiento de la responsabilidad, es una variable mediadora entre las dos...

  12. Relación entre los movimientos oculares, la comprensión lectora y el rendimiento escolar

    Montero-Rodríguez, Carmen María

    2013-01-01

    Las dificultades de lectura que manifiestan algunos alumnos es una cuestión preocupante para docentes y profesionales de la enseñanza. Si bien, es habitual que, de manera preventiva no se evalúen las dificultades neurológicas relacionadas con la funcionalidad visual. En este trabajo se pretende comprobar si existe algún tipo de relación entre el rendimiento escolar que obtienen alumnos de educación primaria, la comprensión lectora y la motilidad ocular. La investigación que se lleva a cabo...

  13. Relación entre movimientos sacádicos, lectura y rendimiento escolar

    Alonso-Gutiérrez, Miriam

    2013-01-01

    La lectura es un elemento fundamental para el aprendizaje escolar. Para poseer una lectura eficaz es necesario combinar alta velocidad con alta comprensión y, si no se lleva a cabo como se debe, es necesario mejorarla conociendo todos los procesos que intervienen. Den tro de los procesos de percepción de la lectura se encuentra la visión, de la que el siguiente estudio destaca la importancia de los movimientos sacádicos. En este trabajo se analiza la relación existente entre los movi...

  14. Alfred Binet entre illusionnisme, spiritisme et cinéma des origines

    Berton, Mireille

    2011-01-01

    À partir de l’incursion d’Alfred Binet dans le monde de la prestidigitation, cet article tente de retracer la logique des interactions qui se sont nouées, à la fin du XIXe siècle, entre les domaines de la psychologie expérimentale, de la magie, du spiritisme et du cinéma des premiers temps. Fournissant une véritable théorie psychologique de la prestidigitation, l’étude de Binet va contribuer à renforcer la crédibilité d’une profession ravie d’une telle caution scientifique, tout en confortant...

  15. Xopan y Tonalco, los colores de las estaciones entre los antiguos nahuas

    Dupey García, Elodie

    2013-01-01

    Note portant sur l’auteur COLORES, LUCES Y ESTACIONES EN LA COSMOVISIÓN NAHUA En las culturas indígenas de México, como en muchas sociedades antiguas y tradicionales, los colores mantienen relaciones esenciales con los elementos del medio ambiente y entre ellos los fenómenos meteorológicos y astronómicos. Esto parece lógico si recordamos que el primer contacto del ser humano con el cromatismo se da en la naturaleza donde se producen deslumbrantes manifestaciones celestes y coloreadas como el ...

  16. Convergences entre économie et sociologie autour du concept de réseau social

    Barbié, Olivier

    2010-01-01

    Il est notoire que la relation traditionnelle entre économie et sociologie est le conflit. Mais je montre que l'importance de ce conflit est minorée par les économistes. Car si la sociologie, initialement positiviste, s'est construite par opposition à l'économie classique, l'ensemble des écoles économiques marginalistes se sont elles aussi construites par opposition à la sociologie positiviste. Lorsque le dialogue théorique existe, il passe par la sociologie économique. Certains voudraient as...

  17. Integração entre epidemiologia e internet

    Sérgio Ribeiro dos Santos

    2000-12-01

    Full Text Available O presente estudo tem como objetivo apresentar algumas reflexões teóricas sobre a Internet como uma ferramenta de integração no serviço de epidemiologia. Nessa perspectiva, focaliza a epidemiologia e a Internet, a Internet e a pesquisa cooperativa, e, por fim, a importância da Internet no processo de comunicação epidemiológica. A integração entre o saber epidemiológico e o uso da Internet para divulgação do conhecimento é enfatizada como um dos maiores beneficios dessa tecnologia que globaliza a informação e transcende as formas tradicionais de comunicação. Todavia, ressalta-se que essa tecnologia, por si só, não é a solução para resolver os problemas funcionais dos sistemas de informação em saúde.

  18. El rostro bifronte de la ciencia: notas sobre la relación entre ciencia e ideología en Habermas y Althusser

    Martínez, Lisandro Alejo

    2015-01-01

    El presente trabajo aborda la relación entre ciencia e ideología a través de la revisión crítica de las perspectivas de Jürgen Habermas y Louis Althusser. Nos interesa indagar sobre el carácter difuso de los límites entre ambos conceptos en el contexto del capitalismo tardío, de donde surge la pregunta acerca de si es posible pensar la ciencia como ideología. Si fuera así, ¿cuáles son los rasgos de la ideología y de la ciencia orientados a trascender la oposición entre verdad y falsedad? Para...

  19. Relaciones entre déficit público y ahorro privado: Aproximaciones al caso colombiano

    Alberto Carrasquilla; Hernán Rincón

    1990-01-01

    Aquí analizamos esta pregunta: si el déficit aumenta hoy con un nivel de gasto dado, ¿qué pasa con el capital de largo plazo de la economía? Si el acervo sube, el consumo privado, bajo la hipótesis del Ingreso Permanente, subirá y el ahorro cae. Empíricamente, esto implica una correlación negativa entre déficit y ahorro privado. El trabajo se basa en una discusión de aquella correlación. A nivel teórico estas ideas se discuten bajo la Hipótesis de Equivalencia Ricardiana (HER).El trabajo pres...

  20. EntreComp: The Entrepreneurship Competence Framework.

    BACIGALUPO MARGHERITA; KAMPYLIS PANAGIOTIS; Punie, Yves; VAN DEN BRANDE Lieve

    2016-01-01

    The development of the entrepreneurial capacity of European citizens and organisations is one of the key policy objectives for the EU and Member States. Ten years ago, the European Commission identified sense of initiative and entrepreneurship as one of the 8 key competences necessary for a knowledge-based society. The EntreComp framework presented in this report proposes a shared definition of entrepreneurship as a competence, with the aim to raise consensus among all stakeholders and to est...

  1. SiC Technology

    Neudeck, Philip G.

    1998-01-01

    Silicon carbide (SiC)-based semiconductor electronic devices and circuits are presently being developed for use in high-temperature, high-power, and/or high-radiation conditions under which conventional semiconductors cannot adequately perform. Silicon carbide's ability to function under such extreme conditions is expected to enable significant improvements to a far-ranging variety of applications and systems. These range from greatly improved high-voltage switching [1- 4] for energy savings in public electric power distribution and electric motor drives to more powerful microwave electronics for radar and communications [5-7] to sensors and controls for cleaner-burning more fuel-efficient jet aircraft and automobile engines. In the particular area of power devices, theoretical appraisals have indicated that SiC power MOSFET's and diode rectifiers would operate over higher voltage and temperature ranges, have superior switching characteristics, and yet have die sizes nearly 20 times smaller than correspondingly rated silicon-based devices [8]. However, these tremendous theoretical advantages have yet to be realized in experimental SiC devices, primarily due to the fact that SiC's relatively immature crystal growth and device fabrication technologies are not yet sufficiently developed to the degree required for reliable incorporation into most electronic systems [9]. This chapter briefly surveys the SiC semiconductor electronics technology. In particular, the differences (both good and bad) between SiC electronics technology and well-known silicon VLSI technology are highlighted. Projected performance benefits of SiC electronics are highlighted for several large-scale applications. Key crystal growth and device-fabrication issues that presently limit the performance and capability of high temperature and/or high power SiC electronics are identified.

  2. Mechanical instabilities and piezoresistivity of SiGe/Si microtubes

    Zhang, Li; Dong, Lixin; Nelson, Bradley J.

    2007-10-01

    Mechanical instabilities and piezoresistivity of individual rolled-up SiGe/Si microtubes are investigated using nanorobotic manipulation. By applying this technique, as-fabricated one-end-fixed SiGe/Si microtubes can be cut and picked up from the substrate to examine their mechanical and electromechanical properties in a free space. Individual SiGe/Si microtubes show typical Euler buckling when the uniaxial compressive load is larger than a critical value. Moreover, experiments show that 1.6-turn rolled-up SiGe/Si microtubes have similar mechanical stability to ideal seamless tubes though the former ones have a spiral-like cross sectional area instead of an ideal ring. According to the measured I-V properties, SiGe/Si microtubes show positive piezoresistivity under compressive loads.

  3. Liste des conseillers municipaux de Paris ayant siégé entre 1944 et 1977

    2016-01-01

    Alexandre-Debray Janine (1910), de 1947 à 1971, Amiot André (1905-1950), de 1945 à 1947, André Max (1893-1977), de 1944 à 1947, Assouad Lionel (1930), depuis 1971, Astier Pierre (1912-1991), de 1965 à 1977, Astier Marius (1888-1959), de 1945 à 1959, Auburtin Jean (1904-1981), de 1947 à 1965, Auburtin-Myers Georgie (1904-1987), de 1971 à 1977, Auguet Gaston (1904-1986), de 1935 à 1940 et de 1945 à 1947, Ayrignac Joseph (1903-1989), de 1965 à 1977, Bagard Edmond (1887-1972), de 1952 à 1965, Bai...

  4. La terminologie médicale du XVIe siècle entre tradition et innovation

    Mecking, Volker

    2014-01-01

    A la Renaissance, le corps humain devient un véritable objet de la science. Sur fond d'autonomisation des sciences, de multiples travaux consacrés au corps apparaissent, dont le traité fondateur d'anatomie en langue latine, De humani corporis fabrica (Sur le fonctionnement du corps humain) d'André Vésale. (1514-1564), qui fait date dans l'histoire de la médecine A un moment où, depuis la publication de l'ordonnance de Villers-Cotterêts (1539) de François Ier, le français (préclassique) commen...

  5. Aplicación de extracción en fase sólida magnética acoplada a sistemas de separación instrumentales para el análisis de residuos de antibióticos en leche

    Ibarra Ortega, Israel Samuel

    2013-01-01

    El uso de antibióticos como promotores del crecimiento en animales destinados al consumo humano representa una práctica frecuente, dentro de los antibioticos más usados con esta finalidad se encuentran las sulfamidas, quinolonas y tetraciclinas. Su aplicación indiscriminada puede ocacionar que residuos de estos persistan y puedan ocasionar problemas al consumidor (alergias, problemas gastrointestinales, desarrollo de resistencias, entre otros), a causa de esta problemática se han desarrollado...

  6. A comparative study of electroluminescence from Ge/SiO2 and Si/SiO2 films

    Ma Shu-Yi; Chen Hui; Xiao Yong; Ma Zi-Jun; Sun Ai-Min

    2004-01-01

    Ge/SiO2 and Si/SiO2 films were deposited using the two-target alternation magnetron sputtering technique. The Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures were fabricated and their electroluminescence (EL) characteristics were comparatively studied. Both Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures have rectifying property. All the EL spectra from the two types of the structure have peak positions around 650-660 nm. The EL mechanisms of the structures are discussed.

  7. SiOx layer formation during plasma sputtering of Si and SiO2 targets

    Deposition of SiOx layers of variable composition onto silicon wafers was performed by co-sputtering of spaced Si and SiO2 targets in argon plasma. Coordinate dependences of the thickness and refractive index of separately deposited Si and SiO2 layers and the SiOx layer grown during co-sputtering of targets were determined using optical techniques. It was shown that the SiOx layer composition is not equal to a simple sum of thicknesses of separately deposited Si and SiO2 layers. The coordinate dependences of the Si and SiO2 layer thicknesses were calculated. To fit the calculated and experimental data, it is necessary to assume that no less than 10% of silicon is converted to dioxide during co-sputtering. A comparison of the coordinate dependences of the IR absorbance in SiO2 and SiOx layers with experimental ellipsometric data confirmed the presence of excess oxygen in the SiOx layer. Taking into account such partial oxidation of sputtered silicon, composition isolines in the substrate plane were calculated. After annealing of the SiOx layer at 1200oC, photoluminescence was observed in a wafer area predicted by calculations, which was caused by the formation of quantum-size Si nanocrystallites. The photoluminescence intensity was maximum at x = 1.78 ± 0.3, which is close to the composition optimum for ion-beam synthesis of nanocrystals.

  8. a-Si/c-Si heterojunction solar cells on SiSiC ceramic substrates

    LI Xudong; XU Ying; CHE Xiaoqi

    2006-01-01

    Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great changein cell's structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell's efficiency.A conversion efficiency of 3.42% has been achieved on 1cm2 a-Si/c-Si heterojunction solar cell ( Isc =16.93 mA, Voc =310.9 mV, FF =06493, AM =1.5 G,24 ℃), while the cell with diffused homojunction only gotan efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.

  9. The property of Si/SiGe/Si heterostructure during thermal budget characterized by HRXRD

    Si/SiGe/Si heterostructures grown by ultra-high-vacuum chemical vapor deposition (UHVCVD) were characterized by Rutherford backscattering/Channeling (RBS/C) together with high resolution X ray diffraction (HRXRD). High quality SiGe base layer was obtained. The Si/SiGe/Si heterostructures were subject to conventional furnace annealing and rapid thermal annealing with temperature between 750 degree C and 910 degree C. Both strain and its relaxation degree in SiGe layer are calculated by HRXRD combined with elastic theory, which are never reported in other literatures. The rapid thermal annealing at elevated temperature between 880 degree C and 910 degree C for very short time had almost no influence on the strain in Si0.84Ge0.16 epilayer. However, high temperature (900 degree C) furnace annealing for 1h prompted the strain in Si0.84Ge0.16 layer to relax

  10. Peces de Entre Ríos

    Miquelarena, Amalia M.

    2013-01-01

    Esta contribución forma parte de los resultados del PICT 153 de la Agencia Nacional de Promoción Científica y Técnica, dirigido por la autora, entre cuyos objetivos se encuentra la transferencia del conocimiento. Es así, que la presente iconografía, tiene como propósito difundir a diferentes niveles de la sociedad la ictiofauna de una de nuestras provincias mesopotámicas contribuyendo de esta manera a la educación ambiental y al manejo y conservación de los recursos naturales.

  11. Flexible micromorph tandem a-Si/µc-Si solar cells

    Söderström, Thomas; Haug, Franz-Joseph; Terrazzoni-Daudrix, Vanessa; Ballif, Christophe

    2010-01-01

    The deposition of a stack of amorphous (a-Si:H) and microcrystalline (µc- Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of µc-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the µc-Si:H cell and the light-induced degradation of the a- Si:H cell. As a result,...

  12. Relación entre variables neurocognitivas y personalidad en delincuentes

    Juan Antonio Becerra García

    2014-12-01

    Full Text Available Recientes estudios muestran que rasgos de personalidad del Modelo de los Cinco Factores y funciones neurocognitivas frontales comparten una misma base neurobiológica. En población penitenciaria las relaciones entre estas funciones y rasgos ha sido poco explorada. Este estudio pretende examinar la relación entre personalidad y funciones neurocognitivas en delincuentes y determinar si las medidas de funcionamiento neurocognitivo frontal contribuyen a predecir algún porcentaje de varianza en rasgos de personalidad de muestras penitenciarias. Noventa y nueve hombres (distribuidos en grupos: agresores sexuales de adultos, delincuentes no sexuales y grupo control realizaron el Inventario de Personalidad NEO de Cinco Factores (NEO-FFI y el Trail Making Test (TMT, partes A y B. La ejecución en la parte A del TMT se relaciono con el nivel de Extraversión de los delincuentes sexuales y con el nivel de Neuroticismo de delincuentes no sexuales y explica un porcentaje significativo de la varianza de estos dominios de personalidad en ambos grupos. En conclusión, la relación entre el funcionamiento neurocognitivo y la personalidad parece ser diferente en función del tipo de delito cometido, aunque los resultados deben ser interpretados de forma preliminar.

  13. RITUAL E XAMANISMO ENTRE OS KAINGANG: O TEMPO E A SOCIOCOSMOLOGIA DOS ESPAÇOS RITUAIS

    Alexandre Magno Aquino

    2014-06-01

    Full Text Available A conexão espaço-tempo é interpretada a partir de dados etnográficos e de análise de (espaços rituais que indicam formas de relação social entre os Kaingang fundadas na reciprocidade de kamë e kanhru krë, as metades patrilineares e exogâmicas. Essa reciprocidade é constantemente afirmada no contexto intra e interaldeão por meio de regras de etiqueta e arranjos institucionais que envolvem, principalmente, o parentesco, o xamanismo e a liderança. De fato, os Kaingang relacionam-se entre si e com os Outros, que compõem seu cosmos, a partir da interação entre os que pertencem a uma ou outra metade, dos kujá (xamã e dos pa i (cacique, que se articulam, nesse caso, para fundar aldeias na região litorânea.

  14. Effect of Si/Si1-yCy/Si Barriers on the Characteristics of Si1-xGex/Si Resonant Tunneling Structures

    HAN Ping; CHENG Xue-Mei; Masao Sakuraba; YoungCheon Jeong; Takashi Matsuura; Junichi Murota

    2000-01-01

    P-type double barrier resonant tunneling diodes (RTD) with the single Si0.6Ge0.4 quantum well and double Si0.6 Ge0.4 spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si1-yCy layer on the characteristics of the devices was shown by comparing the current-voltage (Ⅰ-Ⅴ) characteristics of RTD's of the barriers of Si layers with that of Si/Si1-yCy/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/Si1-yCy/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/Si1-yCy/Si barriers. The possible mechanism for the observed Ⅰ-Ⅴcharacteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si1-yCy layers in the Si/Si1-yCy/Si barriers.

  15. Funciones: traducción entre representaciones

    Modesto SIERRA VÁZQUEZ

    2009-11-01

    Full Text Available RESUMEN: La traducción entre diferentes formas de representación es un aspecto esencial en la enseñanza y en el aprendizaje de las funciones, ya que permite que el alumno capture el comportamiento de una función desde diversos ángulos enriqueciendo su comprensión. En este trabajo se expone el concepto de representación en matemáticas, su evolución histórica referida al concepto de función, la traducción entre diferentes representaciones y se proponen actividades didácticas para el trabajo en el aula.ABSTRACT: The translation between differents systems of representation is an important aspect in the teaching and learning of functions, because it allows the student to acquire the behaviour of functions from differents points of view, enriching its understanding. In this paper, we expose the concept of representation in Mathematic Education, its historie evolution in relation with the concept of function, the translation between different forms of representation and we propose didactical activities for the work in the classroom.

  16. Entre la Venadita y la Medusa

    Valcárcel, Amelia

    2008-06-01

    Full Text Available Feminism has made in the last decades relevant advances towards equity between men and women in western societies. However, both mysogyny and gynophobia are still at work, giving as a result a «deflation of expectations» among women who enter the worlds of politics, information, corporations, economic power, knowledge, religion or art, and find a glass ceiling in full operation. The paper focuses on women artists, examines the anger expressed in feminist art as an answer to exclusion, and argues for feminist strategies of analysis and correction of inequalities.

    El feminismo ha conseguido en los últimos años importantes avances hacia la igualdad entre hombres y mujeres en las sociedades occidentales. Y, sin embargo, tanto la misoginia como la ginofobia siguen vigentes, provocando una «deflación de expectativas » entre las mujeres que se incorporan a los mundos de la política, la información, las organizaciones empresariales, el poder económico, el saber, la religión o la creatividad, y se topan con el techo de cristal a pleno funcionamiento. El artículo se centra en las mujeres creadoras para examinar la cólera expresada en el arte feminista como respuesta a la exclusión y defender estrategias feministas de análisis y corrección de desigualdades.

  17. ARTICULAÇÕES ENTRE VERDADE E SUBJETIVIDADE NOS ÚLTIMOS ESTUDOS DE MICHEL FOUCAULT: SOBRE A SEPARAÇÃO ENTRE VERDADE E ESPIRITUALIDADE

    Daniel Verginelli Galantin

    2012-07-01

    Full Text Available Resumo: Neste artigo apresentamos algumas características concernentes à vinculação entre verdade e subjetividade nos estudos de Michel Foucault realizados durante a década de 1980. Para isso, iniciamos com uma breve introdução onde apresentamos o novo eixo das pesquisas de nosso autor, as técnicas de si. Em seguida nos concentramos em algumas aulas do curso Hermenêutica do Sujeito, onde Foucault aponta para uma separação entre filosofia e espiritualidade no decorrer da história da filosofia, separação que tem como marco a emergência da teologia. Após fazermos uma breve contraposição entre o modo como se articulam verdade e sujeito nos estudos de Foucault (realizados na década de 1970 sobre a época moderna, em comparação com as filosofias clássicas e helênicas, defendemos que tal separação entre filosofia e espiritualidade pode ser tomada como um dos pontos significativos a partir dos quais podemos entender a articulação entre verdade e subjetividade nos últimos estudos de Foucault, assim como suas implicações políticas.Abstract: In this article our goal is to present some of the characteristics which concern the vinculation between truth and subjectivity on Michel Foucault’s 1980 research. So we begin by a short introduction where it’s presented the new axis of our author’s work, the technics of the self. After that we focus in some of the classes from Hermeneutics of the Subject on which Foucault points out a separation between philosophy and spirituality in the middle of the history of philosophy; that separation is due to the emergence of theology. After a quick contraposition between the way which truth and subject are articulated on Foucault’s studies on modernity (made on the 1970’s, and the way they are articulated on classic and hellenic philosophies, we defend that such separation between truth and spirituality may be taken as a significant point by which we can understand the articulation

  18. Optical characterization of Si nanocrystals in Si-rich SiOx and SiOx/SiO2 multilayers grown by ion beam sputtering

    Si-rich SiOx single-layer and SiOx/SiO2 multilayer (ML) films have been prepared by ion beam sputtering under various conditions of stoichiometry of the SiOx layer and deposition temperature (TS). Annealing at 1100 deg. C leads to the formation of Si nanocrystals in the SiOx layers. The phase separation between SiO2 matrix and Si nanocrystals is more clearly seen at higher TS. High-resolution transmission electron microscopy images clearly demonstrate the existence of Si nanocrystals, which exhibit photoluminescence (PL) in the visible range. The PL intensity of the MLs decreases with increasing x or TS, which turns out to be caused by the reduction of the nanocrystalline Si fraction. The PL spectra are blue-shifted by increasing the oxygen content (x) or decreasing the layer thickness, which is consistent with the quantum confinement effect.

  19. Asociación entre creencias religiosas y consumo de drogas lícitas e ilícitas en jóvenes universitarios, según la metodología de pares

    Rodríguez, Jorge; Fernández, Ana María; Hernández, Enrique; Valdés, Macarena; Villalón, Marcelo; Ramírez, Sergio; Román, América; Muñoz, Macarena

    2008-01-01

    En la presente investigación se evalúa si el consumo de drogas estaría asociado a las creencias religiosas. Se trabajó con una muestra de 142 jóvenes universitarios, a quienes se les aplicó un instrumento de preguntas cerradas previamente validado. Los resultados muestran que no existen diferencias significativas en la presencia de creencias religiosas entre consumidores y no consumidores de drogas lícitas, pero si se observan diferencias entre los grupos en el interés por conocer otras relig...

  20. Inherent paramagnetic defects in layered Si/SiO2 superstructures with Si nanocrystals

    Jivanescu, M.; Stesmans, A.; Zacharias, M.

    2008-11-01

    An extensive electron spin resonance (ESR) analysis has been carried out on structures comprised of Si nanoparticles (˜2 nm across) embedded in a regular pattern in an amorphous SiO2 matrix, fabricated by the SiO/SiO2 superlattice approach, with the intent to reveal and quantify occurring paramagnetic defects. The as-grown state is found to exhibit only a Si dangling bond (DB) signal, which through combination of first and second harmonic X-, K-, and Q-band observations in combination with computer spectra simulation, could be conclusively disentangled as solely comprised of overlapping powder pattern spectra of Pb(0) and Pb1 defects, the archetypal intrinsic defects of the Si/SiO2 interface, with no evidence for a D line (Si DBs in disordered Si). This indicates a full crystalline system of randomly oriented Si nanocrystals (NCs). The Pb(0)/Pb1 defect system, pertaining to the NC-Si/SiO2 interfaces, is found to be both qualitatively and quantitatively much alike that of standard (high-quality) thermal Si/SiO2. The system is inherent, remaining unaffected by subsequent UV/vacuum UV irradiations. Relying on the known properties of Pb-type defects in standard microscopic Si/SiO2, the data would comply with Si nanocrystallites, in average, predominantly bordered by (111) and (100) facets, perhaps with morphology, schematically, of [100] truncated (111) octahedrons. Based on independent NC particles counting, there appears a Pb-type center at ˜71% of the Si NCs indicating the latter to be comprised of two subsystems-with or without an incorporated strain relaxing interface defect-which in that case will exhibit drastically different defect-sensitive properties, such as, e.g., photoluminescence (PL). Upon additional optical irradiation, two more defects appear, i.e., the SiO2-associated Eγ' and EX centers, where the observed density of the former, taken as criterion, indicates the SiO2 matrix to be of standard thermal oxide quality. Thus, the properties of the

  1. Si-to-Si wafer bonding using evaporated glass

    Reus, Roger De; Lindahl, M.

    1997-01-01

    Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...

  2. Si nanoparticle interfaces in Si/SiO solar cell materials

    Kilpeläinen, S.; Kujala, J.; Tuomisto, F.;

    2013-01-01

    Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode and photoluminescence. Two positron-trapping interface states are observed after high temperature annealing at 1100 °C. One of the...... states is attributed to the (SiO2/Si bulk) interface and the other to the interface between the Si nanoparticles and SiO2. A small reduction in positron trapping into these states is observed after annealing the samples in N2 atmosphere with 5% H2. Enhanced photoluminescence is also observed from the...

  3. Electronic states at Si-SiO2 interface introduced by implantation of Si in thermal SiO2

    Interface traps due to excess Si introduced into the Si-SiO2 system by ion implantation are investigated. Implanted oxides are shown to have interface traps at or slightly above the Si conduction band edge with densities proportional to the density of off-stoichiometric Si at the Si-SiO2 interface. Diluted oxygen annealing is shown to result in physical separation of interface traps and equilibrium substrate electrons, demonstrating that ''interface'' states are located within a 0.5 nm thick layer of SiO2. Possible charge trapping mechanisms are discussed and the effect of these traps on MOS transistor characteristics is described using a sheet charge model. (author)

  4. Resonant Tunnelling and Storage of Electrons in Si Nanocrystals within a-SiNx/nc-Si/a-SiNx Structures

    WANG Xiang; HUANG Jian; ZHANG Xian-Gao; DING Hong-Lin; YU Lin-Wei; HUANG Xin-Fan; LI Wei; XU Jun; CHEN Kun-Ji

    2008-01-01

    @@ The a-SiNx/nanocrystalline silicon (nc-Si)/a-SiNx sandwiched structures with asymmetric double-barrier are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on p-type Si substrates. The nc-Si layer in thickness 5nm is fabricated from a hydrogen-diluted silane gas by the layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layers are 3nm and 20nm,respectively. Frequency-dependent capacitance spectroscopy is used to study the electron tunnelling and the storage in the sandwiched structures.Distinct frequency-dependent capacitance peaks due to electrons tunnelling into the nc-Si dots and capacitance-voltage (C- V) hysteresis characteristic due to electrons storage in the nc-Si dots are observed with the same sample.

  5. Un pequeño aumento en el espaciado entre letras favorece la lectura en niños disléxicos

    Victoria Panadero; Manuel Perea; Pablo Gómez

    2012-01-01

    Varias investigaciones recientes han mostrado que un ligero aumento del espaciado entre las letras (respecto al espaciado estándar) produce tiempos de lectura más rápidos en los niños con dislexia, así como mejoras en la comprensión de los textos. Si bien el aumento en el espaciado de las letras no “cura” la dislexia, sí permite una mejora en el proceso de lectura. Es importante remarcar que la posibilidad de modificar el espaciado entre letras se encuentra disponible en los programas de proc...

  6. Rehabilitació del magatzem de xarxes al Moll de Pescadors : la gastronomia com a articulació entre la ciutat i la pesca

    Roig Malaret, Agustí

    2015-01-01

    L’exercici proposa l’aproximació de la ciutat al Moll de Pescadors a partir del tractament dels diferents espais, articulats per la gastronomia. Un bar de pescadors, unes societats gastronòmiques i el restaurant d’alta cuina de la Llotja de Barcelona. Aquesta acull la confraria i una escola de cuina, creant en tot moment una contraposició entre el món pesquer i la ciutat que s’explicita al llarg del moll, culminant a l’interior de la Llotja amb un joc de volums enfrontats entre si.

  7. Desigualdades de género en sobrepeso y obesidad entre indígenas chontales de Tabasco, México

    Marcelina Cruz-Sánchez; Esperanza Tuñon-Pablos; Martha Villaseñor-Farías; Guadalupe del Carmen Álvarez-Gordillo; Ronald Nigh-Nielsen

    2012-01-01

    Antecedentes: La obesidad se ha convertido en una epidemia global (OMS) y, aunque se sabe que afecta por igual a toda la población, las mujeres aparecen con más obesidad y obesidad central. Se desconoce el porqué de este fenómeno, o si adquiere características específicas entre la población indígena. Objetivo: identificar las desigualdades de género que subyacen al fenómeno del cuerpo con sobrepeso y obesidad entre indígenas chontales de Tabasco. Materiales y métodos: estudio cualitativo con ...

  8. Educational Selection Between Public School and Private School in Galicia Elección Educacional Entre Escuela Pública y Escuela Privada en Galicia

    Prof. María Jesús Freire; Prof. José Venancio Salcines

    1999-01-01

    Este trabajo tiene como objeto analizar la elección educativa entre escuela pública y escuela privada para los siguientes niveles educativos: infantil, primaria y secundaria en el contexto de los hogares de Galicia (España). Este artículo también analiza en que medida está relacionado el tipo de centro educativo al que asisten los niños con la renta familiar y, la educación recibida por los padres; de esta forma, esperamos aprender algo mas acerca de la desigualdad que existe entre los dos si...

  9. La relación entre educación superior y mercado de trabajo en México. Una breve contextualización

    Alejandro Márquez Jiménez

    2011-01-01

    El documento analiza la relación que se establece entre la educación superior y el mercado de trabajo en México, destacando el problema del desa-juste entre la oferta y la demanda de profesionistas en el mercado laboral. A partir del análisis de diversas fuentes oficiales de información sobre la situación del empleo en México, se concluye que el problema del desajuste es un hecho que se manifiesta a través del desempleo y el subempleo, si bien, existen problemas con su conceptualización y for...

  10. Relación entre la heterogeneidad del paisaje y la riqueza de especies de flora en cuencas costeras del estado de Veracruz, México

    Ángel G. Priego; Patricia Moreno Casasola; José Luis Palacio Prieto; Jorge López Portillo; Daniel Geissert Kientz

    2003-01-01

    La heterogeneidad del paisaje varía en el espacio dependiendo de la proporción entre polígonos y unidades tipológicas. La alta variabilidad del espacio geográfico le confiere una elevada connotación ecológica, lo cual sugiere una estrecha relación con la distribución de la biodiversidad. El objetivo de este estudio es conocer si se puede predecir la riqueza de especies a través de indicadores de variabilidad espacial. Para esclarecer esto, se exploró la relación entre heterogeneidad del paisa...

  11. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    Reinaldo Welti

    2002-01-01

    En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el...

  12. El cardenal Guillem Ramón de Vich y las relaciones entre Roma y Valencia. a comienzos del siglo XVI

    Gómez-Ferrer, Mercedes

    2012-01-01

    Si en primera instancia pensamos en el propósito que nos reúne con motivo de este coloquio en Tours, el papel de los cardenales en la transferencia de fórmulas artísticas renacentistas entre Italia y los diferentes países europeos, y nos centramos en la ciudad de Valencia, el primer pensamiento se vierte hacia la familia Borja. Y en efecto, el fecundo capítulo de relaciones culturales entre Valencia e Italia en la transición de los siglos XV al XVI, pasa necesariamente por la consideración de...

  13. SOCIALISMO ENTRE GLOBALIZACIÓN Y MERCADO

    Mario González Arencibia

    2011-12-01

    Full Text Available Desde finales del siglo XX, el término “globalización” ha venido multiplicando su presencia tanto en el lenguaje cotidiano como en la jerga especializada de las distintas disciplinas sociales, de tal modo que a la fecha actual son ya innumerables los documentos y los discursos en los cuales dicho término es ampliamente empleado. Ello es resultado de que, en la palabra “globalización” parecen resumirse las principales transformaciones que se están produciendo desde el siglo pasado, entre las cuales ha sido trascendente el derrumbe del socialismo como sistema mundial. Asociado a esto también han sido variados los criterios acerca de las posibilidades de la práctica de mercado y de la conexión a la globalización de los antiguos y actuales países socialistas.

  14. Argentina: entre o Mercosul e a Alca

    Raúl Bernal-Meza

    2001-12-01

    Full Text Available Este artigo procura mostrar que a Argentina não está numa encruzilhada na sua política externa, tendo que escolher entre Mercosul ou Alca. Ao contrário, a Argentina vê o Mercosul como um caminho que leva à Alca, afirmando uma posição que se tornou possível depois da confluência de outros fatores, como a posição brasileira frente a Alca e o modelo de integração regional proposta para o Mercosul.This article seeks to show that Argentina is not in crossroads in your foreign policy, having to choose between Mercosur and FTAA. In contrast, Argentina sees Mercosur as a way that leads to FTAA, affirming a position that become possible after a confluence of others factors, as the Brazilian position front Alca and the model of regional integration proposal for Mercosur.

  15. INTERFACE ENTRE MEMÓRIA E LEITURA

    Pedro Nunes de Castro

    2008-04-01

    Full Text Available Leitura e memória são realidades que se coadunam, na medida em que são interdependentes. Esse artigo nasce a partir de uma afirmação de Ivan Izquierdo, neurologista e especialista em memória. Ele assevera que a leitura é a forma mais completa de exercitar a memória. Busco subsídios, essencialmente na Psicologia Cognitiva, para entender essa categórica afirmação. Relaciono alguns aspectos sobre o processamento de textos, e classifico as memórias conforme a função, conteúdo e tempo de duração. A partir disso, delineio a interface comum e intrínseca entre essas duas realidades.

  16. GUVERNAREA DIGITALA SI MODELELE SALE

    Mihaela SAVA; Sofia Elena COLESCA

    2007-01-01

    Aceasta lucrare descrie modele alternative de guvernare electronica, in concordanta cu abordarile diferite ale guvernului In legatura cu posibilitatile oferite de ICT (suport pentru informatii, comunicare si interactiune, managementul cunostintelor). Mai precis, este vorba de o trecere in revista si o analiza a modelelor de guvernare dezvoltate de o initiativa internationala orientata spre cresterea si sustinerea utilizarii ICT (tehnologiile informatiei si comunicatiilor) in contextul guverna...

  17. Photoluminescence from SiO sub 2 /Si/SiO sub 2 structures

    Photopoulos, P

    2003-01-01

    Si layers were developed on pre-oxidized Si wafers by decomposition of silane in a low pressure chemical vapour deposition reactor. By keeping the deposition time constant (2 min) three sets of samples were fabricated at deposition temperatures equal to 580, 610 and 625 deg C. The deposited Si layers were thinned by high temperature dry oxidation thus forming SiO sub 2 /Si/SiO sub 2 structures. Room temperature photoluminescence (PL) measurements showed that for those samples in which the thickness of the remaining Si layer was greater than approx 6 nm, the spectra exhibited a peak at approx 650 nm. Prolonged oxidations led to the formation of SiO sub 2 /nanocrystalline-Si/SiO sub 2 structures in which the thickness of the remaining nanocrystalline Si (nc-Si) layer was smaller than 3 nm. The PL spectra obtained from these structures were at least ten times stronger compared to the previous ones. The PL peak wavelength exhibited a weak dependence on the nc-Si layer thickness shifting from 800 to 720 nm for nc-...

  18. Reliability implications of defects in high temperature annealed Si/SiO2/Si structures

    High-temperature post-oxidation annealing of poly-Si/SiO2/Si structures such as metal-oxide-semiconductor capacitors and metal-oxide-semiconductor field effect transistors is known to result in enhanced radiation sensitivity, increased 1/f noise, and low field breakdown. The authors have studied the origins of these effects from a spectroscopic standpoint using electron paramagnetic resonance (EPR) and atomic force microscopy. One result of high temperature annealing is the generation of three types of paramagnetic defect centers, two of which are associated with the oxide close to the Si/SiO2 interface (oxygen-vacancy centers) and the third with the bulk Si substrate (oxygen-related donors). In all three cases, the origin of the defects may be attributed to out-diffusion of O from the SiO2 network into the Si substrate with associated reduction of the oxide. The authors present a straightforward model for the interfacial region which assumes the driving force for O out-diffusion is the chemical potential difference of the O in the two phases (SiO2 and the Si substrate). Experimental evidence is provided to show that enhanced hole trapping and interface-trap and border-trap generation in irradiated high-temperature annealed Si/SiO2/Si systems are all related either directly, or indirectly, to the presence of oxygen vacancies

  19. Las relaciones compositivas entre cine y arquitectura

    Luis Villareal Ugarte

    2011-07-01

    Full Text Available El presente texto presenta la cinematografía y, en particular, sus técnicas de creación (construcción como un referente para la proyección de la obra arquitectónica. Se hace una lectura sobre las posibilidades que surgen en el encuentro entre estas dos disciplinas, siempre desde una perspectiva del proyecto arquitectónico, es decir, desde su concepción-composición. El texto se construyó a partir de las técnicas propias del lenguaje cinematográfico, más relacionadas con la proyección espacial arquitectónica, para ir encontrando paralelos entre ambas expresiones artísticas. Con esta intención, se ha echado mano de bibliografía que, desde una perspectiva compositiva, ayude a comprender las posibilidades que representa esta relación. Igualmente, el texto hace referencia a reconocidas obras arquitectónicas que por su misma composición (y experiencia son muestra de esta actitud creadora. Estas obras ayudan a demostrar la propuesta del autor, y el texto trata de ser una invitación para releer su arquitectura desde otra perspectiva que pueda dar pie para la creación de nuevas obras arquitectónicas. Más que expositiva, la intención principal del texto es propositiva para el lector-compositor de los nuevos espacios.

  20. Relaciones entre asertividad y estilos cognitivos

    Aníbal Meza Borja

    2013-01-01

    Universitarias de nivel socio-económico alto y bajo fueron comparadas en su asertividad (general, AG, defensiva, AD; y expansiva, AE) y en su estilo cognitivo (dependencia-independencia de campo DC-IC). Las de nivel alto tuvieron mayor independencia de campo no difirieron de las de nivel bajo en AG aunque respondían diferencialmente a ciertos ítems. No difirieron en AE pero si en AD, siendo las de nivel alto más asertivas. Los estilos cognitivos y la AD correlacionaban, siendo más asertivas l...

  1. Semiosfera: pliegue entre mundo y lenguaje

    López Cedeño, Francisco

    2014-01-01

    El hombre no puede estructurar la realidad haciendo abstracción de la lengua y de la cultura. Estas mantienen a la realidad en un movimiento continuo. La cultura es capaz de aislar este dinamismo y de ayudar al hombre a actuar porque refleja a la realidad en sí misma, la organiza ideológicamente, y hace mitos de la aventura humana. Si conociéramos los antagonismos que agitan la cultura, podríamos comprender mejor su naturaleza y su función.

  2. Nanomechanical characteristics of annealed Si/SiGe superlattices

    Wu, Ming-Jhang [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Wen, Hua-Chiang, E-mail: a091316104@gmail.com [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wu, Shyh-Chi [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Chung Shan Institute of Science and Technology, CSIST, Taoyuan 325, Taiwan (China); Yang, Ping-Feng; Lai, Yi-Shao [Central Labs, Advanced Semiconductor Engineering, Inc., 26 Chin 3rd Rd., Nantze Export Processing Zone, 811 Nantze, Kaohsiung, Taiwan (China); Hsu, Wen-Kuang [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wu, Wen-Fa [National Nano Device Laboratories, Hsinchu 300, Taiwan (China); Chou, Chang-Pin [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2011-08-15

    In this study, the nanomechanical damage was investigated on the annealed Si/SiGe strained-layer superlattices (SLSs) deposited using an ultrahigh-vacuum chemical vapor deposition (UHVCVD). Nanoscratch, nanoindenter, atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to determine the nanomechanical behavior of the SiGe films. With a constant force applied, greater hardness number and larger coefficients of friction ({mu}) were observed on the samples that had been annealed at 600 {sup o}C, suggesting that annealing of the Si/SiGe SLSs can induce greater shear resistance. AFM morphological studies of the Si/SiGe SLSs revealed that pile-up phenomena occurred on both sides of each scratch, with the formation of some pellets and microparticles. The Si/SiGe SLSs that had been subjected to annealing under various conditions exhibited significantly different features in their indentation results. Indeed, the TEM images reveal slight dislocation propagation in the microstructures. Thus, the hardness and elastic modulus can be increased slightly after annealing treatment because the existence of comparatively unstable microstructures. It is suggested that cracking phenomena dominate the damage cause of Si/SiGe SLSs.

  3. Laser chemical vapor deposition of W on Si and SiO2/Si

    Direct write of W on bare Si and native SiO2/Si substrates has been investigated in an laser chemical vapor deposition (LCVD) system. W deposits on bare Si surface via the Si and/or H2 reduction of WF6 were self-limited in thickness to 200 - 600 Angstrom in both cases. Auger electron spectroscopic analysis showed that Si-H bonds could be poisoning the further growth of W. W deposits on native SiO2/Si were only obtainable via the H2 reduction WF6 in our laser direct-write system. The authors' experimental kinetic study indicates that HF desorption from the surface is the rate-controlling step for W deposition via the H2 reduction WF6

  4. SiC-Si interfacial thermal and mechanical properties of reaction bonded SiC/Si ceramic composites

    Hsu, Chun-Yen; Deng, Fei; Karandikar, Prashant; Ni, Chaoying

    Reaction bonded SiC/Si (RBSC) ceramic composites are broadly utilized in military, semiconductor and aerospace industries. RBSC affords advanced specific stiffness, hardness and thermal. Interface is a key region that has to be considered when working with any composites. Both thermal and mechanical behaviors of the RBSC are highly dependent on the SiC-Si interface. The SiC-Si interface had been found to act as a thermal barrier in restricting heat transferring at room temperature and to govern the energy absorption ability of the RBSC. However, up to present, the role of the SiC-Si interface to transport heat at higher temperatures and the interfacial properties in the nanoscale have not been established. This study focuses on these critically important subjects to explore scientific phenomena and underlying mechanisms. The RBSC thermal conductivity with volume percentages of SiC at 80 and 90 vol% was measured up to 1,200 °C, and was found to decrease for both samples with increasing environmental temperature. The RBSC with 90 vol% SiC has a higher thermal conductivity than that of the 80 vol%; however, is still significantly lower than that of the SiC. The interfacial thermal barrier effect was found to decrease at higher temperatures close 1200 °C. A custom-made in-situ tensile testing device which can be accommodated inside a ZEISS Auriga 60 FIB/SEM has been setup successfully. The SiC-Si interfacial bonding strength was measured at 98 MPa. The observation and analysis of crack propagation along the SiC-Si interface was achieved with in-situ TEM.

  5. XI. Si Heidegger…

    2012-01-01

    C’est avec raison que Lyotard a refusé l’alternative : « si grand penseur, alors pas nazi ; si nazi, pas grand penseur. » Schirmacher, un apologète de Heidegger qui a la malchance de ne pas être pris en compte par l’apologie officielle de Heidegger, répète l’alternative avec sa question : « Est-ce qu’un salaud [Charakterschwein] peut être un grand philosophe ? » Il trouve certes « consternant que Heidegger ait été nazi », mais demande à la fin : « Heidegger était-il nazi ? » Pourtant, ce n’es...

  6. Entre dos fuegos: el arte-ciencia y la guerra entre ciencia y humanidades

    Galanter, Philip

    2011-01-01

    Peer reviewed Hi ha una divisió fonamental d'ordre filosòfic entre la cultura moderna de la ciència i la cultura postmoderna de les humanitats. Aquest distanciament cultural és, entre altres coses, la causa subjacent que explica la poca acceptació de l'art científic i de l'art tecnològic en el món de l'art majoritari. No obstant això, en les dues últimes dècades, l'estudi de la complexitat ha comportat una revolució en les ciències. En aquest treball es postula la viabilitat d'ampliar el p...

  7. Recherche sur la situation linguistique de Biarritz au XVIIIème siècle

    Iglesias, Hector

    1996-01-01

    Version revue et corrigée Il s'agit d'un article offrant une meilleure connaissance des relations tant historiques que linguistiques, nouées au cours des siècles entre les cultures basque et occitane, notamment gasconne, dans le territoire de Biarritz. L'étude de l'onomastique bas-aturienne du territoire biarrot y est réalisée à partir, entre autres, de minutes notariales très souvent encore inexploitées. Iragan denboretako Biarritzeko egoera linguistikoa aztertzen da.

  8. La relation entre prix agricoles et prix alimentaires : une approche macro-économique en France entre 1978 et 2005

    Jean-Pierre Butault

    2008-01-01

    Ce texte examine, sur le plan macro-économique, les relations entre l’agriculture, les industries agro-alimentaires, le commerce et les consommateurs, en France, entre 1978 et 2005. La méthode des comptes de surplus est appliquée aux tableaux entrées-sorties pour mesurer la productivité de l’agriculture et des industries alimentaires et apprécier les transferts de pouvoir d’achat entre les différents agents. L’agriculture inclut la sylviculture et la pêche. Les industries sont divisées en de...

  9. Radiation-induced plasmons in Si-SiO2

    1999-01-01

    The first level plasmons of Si in the pure Si state (corresponding to bonding energy (BE) of 116.95 eV) and in the SiO2 state (corresponding to BE of 122.0 eV) of Si-SiO2 prepared by irradiation hard and soft processing were studied with XPS before and after 60Co radiation.The experimental results indicate thatthere was an interface consisting of the two plasmons,this interface was extended by 60Co radiation, the fractions of the plasmon for Si in the Si-SiO2 werechanged with the variation of radiation dosage,the difference of the change in fraction of plasmonsfor the two kinds of samples was that the soft variedfaster than hard, the change of concentrations inplasmons for both hard and soft Si-SiO2 irradiatedin positive bias field were greater than that in bias-free field.The experimental results are explained from the view point of energy absorbed in form of quantization.

  10. Coocurrencia entre ansiedad y autismo: Las hipótesis del error social y de la carga alostática

    Paula Pérez, Isabel, 1970-

    2013-01-01

    Introducción. El concepto de comorbilidad en trastornos del neurodesarrollo como el autismo resulta, en ocasiones, ambiguo. La coocurrencia entre ansiedad y autismo es clínicamente signifi cativa; sin embargo, no siempre es fácil diferenciar si se trata de una comorbilidad"real", donde las dos condiciones comórbidas son fenotípica y etiológicamente idénticas a lo que supondría dicha ansiedad en personas con un desarrollo neurotípico; si se trata de una ansiedad fenotípicamente alterada por lo...

  11. Entre Pauline Kergomard et Maria Montessori

    Moussy, Bernadette

    2007-01-01

    Au XIXe siècle les références concernant l’éducation de la petite enfance ont pris deux orientations différentes. L’une donne comme modèle la mère éducatrice. Dans l’autre référence,  l’éducatrice très respectueuse de la dynamique de l’enfant, intervient le moins possible. Deux femmes pédagogues sont représentatives de ces courants : D’une part, Pauline Kergomard (inspectrice des écoles maternelles, 1838-1925) auteur de « L’éducation maternelle à l’école » présente comme référence « la mère ...

  12. Heterogeneidade entre Leitores Julgados Competentes pelas Professoras

    Pinheiro Ângela Maria Vieira

    2001-01-01

    Full Text Available O desempenho de leitura de um grupo de crianças de quarta série, julgadas pela professora como leitoras com desenvolvimento normal, foi investigado. Uma medida de desempenho deficiente/competente - baixos níveis de erros e tempos de reação rápidos para as respostas corretas para a leitura em voz alta de palavras reais (variando em familiaridade, regularidade e comprimento e não-palaras (com a mesma estrutura ortográfica das palavras reais e variando em comprimento - foi obtida com o objetivo de estabelecer uma definição de desempenho eficiente de leitura que, por sua vez, serviu de base para a identificação de deficiências, em crianças do mesmo grupo, cujos resultados situaram-se fora da amplitude estabelecida como normal. Dentre esses participantes houve um exemplo de dislexia fonológica e vários casos apresentando danos que afetaram ambos os processos, lexical e fonológico, com uma tendência para o padrão fonológico. A discrepância entre a avaliação da professora e a avaliação cognitiva de leitura conduzida é discutida.

  13. Acidentes de trabalho ocorridos entre adolescentes

    Aline Alcântara Pimenta

    2013-01-01

    Full Text Available Este estudio tuvo como objetivo identificar los accidentes de trabajo producidos entre los adolescentes en una fundación de educación para el trabajo. Estudio descriptivo, cuantitativo que investigó 117 adolescentes trabajadores a través de un cuestionario multidimensional. De los encuestados, el 72,6% eran mujeres, el 80,3% tenían 15 años, el 60% eran pardos y el 62,4% no trabajaba anteriormente. Las actividades más populares realizadas fueron las siguientes: Recepcionista (46,2% y auxiliar administrativo (37,6%. Sufrieron accidentes en el trabajo o antes de llegar a este el 11% de los encuestados, de los cuales 76,9% eran típicos y se produjeron en la tarde (61,5%. Las piernas y los pies fueron los miembros mas heridos (46,2%, seguido por abrasiones y lesiones graves (30,8%. El trabajo de niños y adolescentes pueden presentar agravios, que se clasifican como accidentes. El enfrentamiento de este problema no puede ser pensado sólo en términos de vigilancia de los lugares de trabajo y de las políticas dirigidas a la salud del trabajador; hay una necesidad de una mayor transformación en la estructura de la sociedad, de modo que el trabajo perjudique la salud.

  14. Synthesis and characterization of laminated Si/SiC composites

    Salma M. Naga

    2013-01-01

    Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

  15. Complicaciones obstétricas y médicas en el Trastorno de Déficit Atencional/Hiperactividad (TDAH): ¿hay diferencias entre los subtipos?

    Connie Capdevila-Brophy; José Blas Navarro-Pastor; Josep Artigas-Pallarés; Jordi Obiols-Llandrich

    2007-01-01

    El debate actual sobre los subtipos de Trastorno de Déficit Atencional/ Hiperactividad (TDAH) se centra en determinar si las similitudes y diferencias halladas en la sintomatología asociada aportan evidencia para conceptualizar los subtipos como manifestaciones de distinto trastorno. El objetivo de este estudio retrospectivo ex post facto es investigar las diferencias entre los subtipos de TDAH con predominio de inatención (TDAH-I) (n = 20) y TDAH combinado (TDAH-C) (n = 39) en...

  16. Respuesta de diferentes poblaciones de spongospora subterránea f. sp. subterranea a la rotación entre dos variedades de papa (solanum tuberosum ssp. andigena).

    Jaramillo Villegas, Sonia; Botero Herrera, Juan Manuel

    2011-01-01

    En una zona papera del Oriente de Antioquia - Colombia, se realizaron tres experimentos, para conocer el comportamiento de las variedades ICA Puracé, considerada por los agricultores, como resistente a la sarna polvosa de la papa, y la variedad Diacol Capiro susceptible. Se pretendió evaluar si hay un efecto de la rotación, entre las dos variedades con diferentes poblaciones de Spongospora subterranea f sp. subterranea sobre la sarna polvosa. Se utilizaron quistosoros de 23 poblaciones de S. ...

  17. Perfil psicológico de los jugadores profesionales de balonmano y diferencias entre puestos específicos

    Aurelio Olmedilla; Enrique Ortega; Enrique Garcés de los Fayos; Lucía Abenza; Amador Blas; María Laguna

    2015-01-01

    En este estudio se pretende determinar las características psicológicas para el rendimiento deportivo de los jugadores de balonmano de alto nivel y establecer si existen diferencias entre el perfil psicológico de estos jugadores en función del puesto táctico ocupado. La muestra estuvo compuesta por 80 jugadores profesionales de balonmano, con una edad media de 24.83 (± 5.21) a˜nos. Respecto al puesto de juego, el 30% jugaban de extremo, el 25% de lateral, el 16.3% de central, el 18.7% de pivo...

  18. Paso a paso con Beauvoir en el debate entre materialismo histórico, psicoanálisis y feminismo

    Soza Rossi, Paula V.; Rodríguez Durán, Adriana

    2008-01-01

    Releyendo El segundo sexo de Simone de Beauvoir, nos interesó retomar el debate entre materialismo histórico, psicoanálisis y feminismo a fin de reflexionar sobre sus aportes y las derivaciones actuales de lo inicialmente planteado por la autora. Nuestra inquietud respecto a esa articulación es si establece una continuidad con trabajos anteriores donde ya se hubiera intentado revisar los dualismos y el sesgo de género, ambos presentes en las teorizaciones de nuestras disciplinas de origen: Ps...

  19. Coherencia interna entre la memoria del grado y el currículo de educación infantil

    Franco Borrego, Silvia

    2015-01-01

    El trabajo propuesto refleja el proceso de análisis llevado a cabo por un estudiante de final de Grado, para comprobar la coherencia interna que existe entre la Memoria del Grado de Educación Infantil y el Currículo de Educación Infantil, con el fin de determinar si la formación que adquiere el educando en la titulación siguiendo el Plan de Estudios marcado por la Universidad Complutense de Madrid, se corresponde con las exigencias reales de los maestros en las aulas actuales. El trabajo ...

  20. Relación entre género y salud en los profesionales de enfermería

    Saavedra San Román, Ana Isabel

    2013-01-01

    Se pretende analizar las relaciones entre los indicadores de salud (física, mental, estilos de vida y niveles de cortisol en plasma) y el género desde una perspectiva novedosa, que es incluir la medida del género desde el inicio del proceso investigador (es decir, no sólo aportar datos desagregados por sexo, sino identificar cómo los roles, creencias, estereotipos y relaciones de poder influyen en la salud) para poder identificar si esta variable modula los niveles de salud de los participant...

  1. ¿Explica la selección la divergencia entre las poblaciones del Área Andina Centro Sur?

    Varela, Héctor Hugo; Cocilovo, José Alberto; O'Brien, Tyler G.

    2009-01-01

    Se ha propuesto que las principales fuerzas evolutivas que explican la variabilidad observada en las poblaciones prehistóricas que habitaron el Área Andina Centro Sur, bajo los supuestos de neutralidad selectiva de los caracteres métricos del cráneo y distribución aleatoria del efecto ambiental, son la deriva génica y la migración. En el presente trabajo se evalúa si la divergencia fenotípica observada entre los grupos humanos antiguos del Norte de Chile, Sur de Bolivia y Noroeste de Argentin...

  2. Análisis de la relación entre contabilidad y fiscalidad en Colombia

    Ernesto María Sierra González

    2008-06-01

    Full Text Available La relación entre contabilidad y fiscalidad ha sido una tradición en Colombia, pues es notable la influencia ejercida por las instituciones de carácter público encargadas del control impositivo, en la normativa sobre la cual descansa la práctica contable del país. Si bien se han hecho esfuerzos por separar las dos dimensiones, aún hoy estas permanecen. Con la propuesta de adoptar Normas Internacionales de Contabilidad (NIC, se hace necesario separar las dos esferas. Pero las diferencias en los métodos de cálculo y valoración afectan los resultados de la empresa y por tanto su efecto impositivo. Se trata pues del análisis de esta problemática en aras de garantizar los niveles de recaudo y evitar distorsiones en el mercado.

  3. Relación entre síndrome de burnout, estrategias de afrontamiento y engagement

    Paula Andrea Montoya Zuluaga

    2012-01-01

    Full Text Available Este artículo tiene como finalidad analizar, a partir de las teorías existentes, la relación entre las estrategias de afrontamiento, el síndrome de burnout y el engagement. El síndrome de burnout si bien se desarrolla en un contexto organizacional, es individual y ello ya implica la existencia de factores de riesgo que llegan a activarse (ya sea para posibilitar su aparición por las estrategias de afrontamiento que se asumen o evitar su desarrollo, cuando hay engagement en contextos laborales donde hay presencia de alta carga laboral, bajas recompensas por el oficio llevado a cabo y ambientes laborales en los que no se posibilita la participación para la toma de decisiones.

  4. EUTANASIA, ENTRE LA VIDA Y LA MUERTE ¿QUIÉN Y QUÉ LA DECIDE?

    Araque, Olga Ligia

    2014-01-01

    La eutanasia significa entre varios aspectos la inducción de la muerte sin dolor en interés del destinatario y supone una reducción en laduración de la vida de un enfermo terminal.El daño que se infringe al destinatario es la reducción del tiempo de vida; si el enfermo no es terminal entonces no es caso de eutanasia.Esta se fundamenta en el principio de que nadie puede ser cruel con los demás. La idea más básica de la eutanasia está relacionada con labenevolencia. La vida humana es un valor p...

  5. SiC/SiC composites and application%SiC/SiC复合材料及其应用

    李崇俊

    2013-01-01

    日本开发的Nicalon和Tyranno两种品牌的SiC纤维占有世界上绝对性的市场份额.SiC/SiC复合材料典型的界面层是500 nm厚的单层热解碳(PyC)涂层或多层(PyC-SiC)n涂层,在湿度燃烧环境及中高温条件下界面层的稳定性是应用研究的重点.SiC/SiC复合材料,包括CVI-SiC基体和日本开发的Tyranno hex和NITE-SiC基体等,具有耐高温、耐氧化性和耐辐射性的特点,在航空涡轮发动机部件、航天热结构部件及核聚变反应堆炉第一壁材料等方面正开展工程研制应用.%The two trademarks of Nicalon and Tyranno SiC fibers,developed in Japan,occupy the overwhelming world market.The typical interlayer in SiC/SiC composites is either a single pyrolytic carbon (PyC) coating with a thickness of 500nm or multilayered (PyC-SiC)n coatings.The fiber/matrix interlayer stabilities in SiC/SiC composites are a key research topic for applications in the wet combustion environment with high temperature.The CVI-SiC matrix based SiC/SiC composites,as well as Japan produced Tyranno-hex composites and NITESiC matrix,perform the characteristics of high temperature,anti-oxidation and anti-irradiation,and are having been progressed into engineering application in the fields of aircraft turbine engine components,aerospace thermostructural parts and fusion reactor thermo-structural materials.

  6. Borges y Calvino: La genesis de la novela Si una noche de invierno un viajero

    Tea Štoka

    2005-05-01

    Full Text Available El crítico italiano Cesare Segre1   adscribe la génesis de la novela de Calvino Si una noche de invierno un viajero al cuento de Borges Examen de la obra de Herbert Quain, que figura entre los trece cuentos de Ficciones (1944. En este cuento, Borges describe, analiza y comenta las novelas de Herbert Quain inventadas como si fueran obras literarias reales. Las emplaza al mismo nivel de realidad que las obras dramáticas de Shakespeare, las novelas de Henry James y Gustavo Flaubert.

  7. La sociologie clinique entre psychanalyse et socioanalyse

    Vincent de Gaulejac

    2008-04-01

    Full Text Available L'introduction de la démarche clinique en sociologie conduit à réinterroger les différences et les complémentarités entre la psychanalyse et la sociologie sur trois points : leur façon d'appréhender la question de l'inconscient; le poids respectif des déterminations psychiques et sociales, le travail qu'un sujet peut effectuer sur son histoire pour en modifier le cours. Ces questions ont été l'objet de nombreux débats. Le présent article met en perspective les positions de Sigmund Freud et de Pierre Bourdieu. L'un et l'autre incarnent et défendent des points de vue théoriques qui articulent une théorie de l'homme en société étayée sur une pratique de changement. Confrontation intéressante dans la mesure où les postulats de départ de ces deux auteurs sont très éloignés. Sigmund Freud cherche la clé explicative des comportements humains du côté du registre intra psychique, alors que Pierre Bourdieu la pose du côté de l'intériorisation des structures sociales. Pourtant à partir de prémisses différents ils se rejoignent sur bien des points. Ces convergences permettent de s'appuyer sur leurs approches pour définir les contours d'une méthodologie qui s'inspire tout à la fois de la psychanalyse et de la socioanalyse.Clinical sociology between psychoanalysis and socioanalysisThe introduction of the clinical approach in sociology lead us to reconsider the differencies and complementarities between psychoanalysis and sociology on three aspects: their way of taking into account the unconscious; the relative weight of social and psychic predeterminations; the work that can be done by somebody on his/her own history in order to modify its course. Those questions have been largely debated. The purpose of this article is to compare on those topics the positions of Sigmund Freud and Pierre Bourdieu. Both develop theories which include a conception of man in society supported by a change practice. The interest of this

  8. ANÁLISIS TEÓRICO DE LA RELACIÓN ENTRE DIVERSIFICACIÓN CORPORATIVA Y RESULTADOS EMPRESARIALES

    Benito Osorio, D.

    2009-01-01

    Full Text Available En este trabajo se presenta una revisión teórica sobre la influencia que ejerce la estrategia de diversificación corporativa sobre los resultados empresariales. La revisión de la literatura efectuada nos permite proponer y justificar explicaciones para dos cuestiones clave que han suscitado el interés de los investigadores en este ámbito, sobre las cuáles no existe aún consenso en la literatura: si existen diferencias entre las rentabilidades de las empresas asociadas a las distintas estrategias de diversificación (distinto grado y/o tipo de diversificación y si el entorno nacional es un factor condicionante de la rentabilidad de las empresas diversificadas.

  9. CONSTRUÇÃO SOCIAL DE SENTIDOS SOBRE A RAVIDEZMATERNIDADE ENTRE ADOLESCENTES

    Nayara Bueno de Araujo

    2015-01-01

    Full Text Available Se buscó comprehender la construcción social de sentidos sobre embarazo-maternidad entre adolescentes embarazadas. Estudio explicativo, realizado en 2014, con 12 adolescentes, por medio de entrevista individual y grupal, observación del contexto local, consulta al documentos y preceptos de Análisis de Discurso Crítica de Fairclough. Se encontró el sentido de compatibilidad entre el embarazo y adolescencia y de contraposición al discurso dominante de embarazo como un problema. El evento respondía al que las adolescentes proyectaban para si, en uno contexto restringido de oportunidades sociales. Lo valoran con base en un ideal social de maternidad y de constitución familiar, prebendo reconocimiento social, comprobación de feminidad y mayor poder y autonomía. Sin embargo, esas ganancias se muestran atravesados por dificultades percibidas, como enfrentar el juicio familiar y el “doloroso” parto. La comprensión contextualizada de estos sentidos y su contenido social y ideológico es esencial al desenvolvimiento de mayor grado de autonomía-responsabilidad de adolescentes.

  10. CORRELATOS ENTRE BIENESTAR SUBJETIVO Y REGULACIÓN EMOCIONAL DEL ENOJO: DIFERENCIAS POR SEXO

    Magali Martínez Pérez

    2014-01-01

    Full Text Available Las experiencias emocionales negativas se asocian con el bienestar subjetivo, pero se ignora si la manera de regularlas se relaciona con los reportes de bienestar. El presente estudio exploró la asociación entre el bienestar percibido y ciertas variables culturales (premisas histórico-socio-culturales e individuales (automonitoreo, estrategias y autoeficacia involucradas en la regulación del en ojo, así como las posibles diferencias sexuales. Participaron 220 residentes que respondieron voluntariamente una batería de pruebas. Se encontró que las creencias culturales y el uso de estrategias que disminuyen la intensidad del enojo se asocian positivamente con el bienestar con amigos y trabajo, y que hay más similitudes que diferencias entre hombres y mujeres en las variables evaluadas. Los hallazgos señalan la importancia de regular apropiadamente emociones negativas como el enojo, a fin de incrementar el bienestar subjetivo de hombres y mujeres.

  11. THERMODYNAMIC STUDIES OF HIGH TEMPERATURE EQUILIBRIA OF THE Si - N, Si - C - H AND Si - O - C - H SYSTEMS

    Kostij, Ž.; Pavlovij, P.; Stefanovij, P.

    1990-01-01

    A model of system thermodynamic equilibrium and the obtained results in the temperature interval of 1000 [K] to 6000 [K] at p = const = 1 [bar] are presented for: 1) the Si-N system for Si3N4 synthesis from Si - powder in a nitrogen thermal arc plasma. 2) the Si-C-H system for SiC synthesis from Si-powder in a propane-butane thermal arc plasma (with added hydrogen) and 3) the Si-O-C-H system for SiC synthesis from SiO2-powder in a propane-butane thermal arc plasma (with added C-powder). The d...

  12. Relaciones entre asertividad y estilos cognitivos

    Aníbal Meza Borja

    2013-09-01

    Full Text Available Universitarias de nivel socio-económico alto y bajo fueron comparadas en su asertividad (general, AG, defensiva, AD; y expansiva, AE y en su estilo cognitivo (dependencia-independencia de campo DC-IC. Las de nivel alto tuvieron mayor independencia de campo no difirieron de las de nivel bajo en AG aunque respondían diferencialmente a ciertos ítems. No difirieron en AE pero si en AD, siendo las de nivel alto más asertivas. Los estilos cognitivos y la AD correlacionaban, siendo más asertivas las mujeres con independencia de campo. Two female samples from high (HS and low (LS social-economic level were evaluated in Assertiveness (General GA, Defensive DA and Expansive EA and in Cognitive Styles (Field Depedence-Independence FD-FI. Both samples differed on cognitive styles, being HS more field independent; both samples did not differed cuantitatively on GA but it could be noted some difference in the kind of assertiveness items to which they responded diferently. No difference was observed on EA but significant differences were found on DA, being HS more assertive.

  13. Methods of radiation effects evaluation of SiC/SiC composite and SiC fibers

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. Several methods for radiation effects evaluation of SiC fibers and fiber-reinforced SiC/SiC composite are presented.

  14. Joining of SiC ceramics and SiC/SiC composites

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method has the potential to facilitate the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent efforts have focused on transferring the joining technology to industry. Several industrial partners have been identified and collaborative research projects are in progress. Investigations are focusing on applying the joining method to sintered a-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  15. Joining of SiC ceramics and SiC/SiC composites

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1996-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method will permit the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent emphasis has been given to technology transfer activities, and several collaborative research efforts are in progress. Investigations are focusing on applying the joining method to sintered {alpha}-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  16. Le mobilier domestique à Lille au XVIIe siècle

    Odile Canneva-Tétu

    2012-01-01

    L'exposition « Lille au XVIIe siècle » présentée au musée des Beaux-Arts de Lille du 15 septembre au 27 décembre 2000 a fourni l'occasion de dresser un premier état des connaissances sur le mobilier civil lillois entre 1600 et 1715. Ce court essai s'appuie sur quelques exemples recensés dans les collections publiques lilloises.

  17. Diffuse x-ray reflectivity of strain-compensated Si/SiGe/SiC multilayer

    The morphology of interfaces in strain-compensated Si/SiGe/SiC superlattices is investigated by means of diffuse x-ray reflection. Various structure models are assumed for an analysis of the experimental data, namely anisotropic ripples, isotropic ripples and a fractal roughness. The type of the structure and the mean distance of the ripples is determined on the basis of experimental data analysis. (author)

  18. Stress and stress monitoring in SiC-Si heterostructures

    Pezoldt, Joerg; Niebelschuetz, Florentina; Cimalla, Volker; Stauden, Thomas [FG Nanotechnology, Institute of Micro- and Nanotechnologies, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Nader, Richard; Masri, Pierre [Groupe d' Etudes des Semiconducteurs, CNRS cc074, UMR 5650, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 5 (France); Zgheib, Charbel [Department of Electrical, Computer Communication Engineering, Notre Dame University, 5725 Deir El Kamar (Lebanon)

    2008-04-15

    Infrared ellipsometry is a valuable tool to investigate the average stress and the stress distribution in thin silicon carbide layers grown on silicon as well as to monitor the changes in the stress state during device processing. It was obtained that low temperature carbonization in combination with low temperature epitaxial growth led to a compressive stress component in the SiC-Si interface region, whereas the average stress state is tensile. Ge incorporation in the interface lowered the tensile residual stress component. Metallization of SiC increases the tensile stress in the SiC on Si. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Advanced SiC fibers and SiC/SiC composites toward industrialization

    In order to establish the industrialization basis of advanced SiC fibers and SiC/SiC composites to be used in nuclear fusion reactors, R and D of Tyranno-SA grade fibers (Cef-NITETM) and NITE-SiC/SiC with sufficient quality control has been carried out. The important elements in this effort are fiber structure control and matrix density and homogeneity control. From the continuous heat treatments of pre-crystallized SiC fibers, the improved uniformity of grain size for radial position in 7-10 μm diameter SiC fibers has been confirmed with the fiber strength over 2.0 GPa. In order to establish stable mass production of NITE-SiC/SiC (Cera-NITETM), with sufficient quality control, efforts on production of mid-products, such as green sheets, prepreg sheets and preforms, have been extensively carried out. The important elements were to improve the homogeneity and density of preform so that the following sintering process has been modified for improving structure control.

  20. Entre/vista a Langdon Winner

    Andrés Lomeña

    2011-12-01

    Full Text Available La ballena y el reactor: Una búsqueda de los límites en la era de la alta tecnología se reeditó en 2008 con un prólogo de Javier Bustamante. Su autor, el politólogo Langdon Winner, ha sido uno de los pioneros en criticar la fascinación tecnológica de Occidente y en reflexionar sobre las consecuencias políticas, sociales y filosóficas de la tecnología. Su preocupación se ha centrado en cómo casi todos los aspectos de la vida humana han quedado sometidos a consideraciones de coste-beneficio. Esto le llevó a escribir un libro cuyo título nace de la epifanía que le hizo entender los problemas más acuciantes de las sociedades altamente tecnologizadas.Winner cuestionó tempranamente el dogma de la neutralidad tecnológica y expuso cómo los artefactos pueden tener intencionalidad política. Para ello usó varios y poderosos ejemplos: los pasos elevados de Long Island, denunciando los propósitos segregacionistas del planeamiento urbano en Nueva York, o la cosechadora mecánica de tomates, que alteró drásticamente la distribución del poder de la agricultura californiana.Si Lewis Mumford puede considerarse el antecesor directo de Winner, muchos otros autores han sido deudores indirectos de sus escritos. Los estudios de la ciencia (con la teoría del actor-red a la cabeza han heredado esa concepción de la tecnología como algo inherentemente político, no como un actor pasivo, frío e imparcial.

  1. Diversidad genética, entre y dentro de los mayores grupos humanos

    Barbujani, G.

    2003-01-01

    Full Text Available Varios estudios están de acuerdo cuando reportan que cerca del 85% de la diversidad del ADN autosomal y de los loci de las proteínas se debe a diferencias entre individuos dentro de la misma población, mientras que las diferencias entre los grupos de diferentes continentes son responsables de solamente 10% de la variación genética total. Estos resultados están en conflicto con nociones populares de razas humanas claramente distintas y relativamente homogéneas, y nos hacen cuestionar la utilidad de clasificaciones étnicas en diagnósticos médicos, en el campo forense y en genética farmacológica. Nuevos datos obtenidos de inserciones polimórficas de Alu y del cromosoma Y confirman los resultados previos, aunque indican una diversidad mayor en algunos (pero no todos los loci del cromosoma Y. Estos datos nos permiten investigar dos preguntas: (1 si las diferencias continentales, aunque pequeñas, son suficientemente grandes como para asignar a individuos a sus continentes basados en sus genotipos; (2 si los genotipos observados se agrupan en grupos de población o continentales cuando el origen de la muestra se ignora. Usando varios métodos estadísticos, veremos que los errores de clasificación son por lo menos de un 30% para los polimorfismos autosomales bi-alélicos, y de un 27% para el cromosoma Y. Cuatro series de datos genéticos de todo el mundo sugieren la existencia de grupos de genotipos diferentes, pero que éstos cuatro grupos no coinciden el uno con el otro. Adicionalmente, estudios de bloques de ADN del genoma humano indican que la mayor parte de dichos bloques es compartida entre los continentes, con solamente un pequeño porcentaje siendo específico a ciertos continentes. Estos resultados no indican que haya una base clara para subdividir a los humanos en grupos biológicamente definidos. Este puede no ser un problema en áreas aplicadas de genéticas, dado que los métodos rápidos para obtener genotipos individuales

  2. Using SI Units in Mechanics.

    Meriam, J. L.

    This paper provides an historical account of the development of the International System of Units (SI), a complete listing of these units, and rules concerning their use and proper abbreviation. Ambiguities concerning the use of the system are explained. Appendices contain conversion factors for U.S. - British to SI units along with several…

  3. SI units in radiation protection

    International System of Units abbreviated as SI units has been adopted by most of the countries of the world. Following this development, the implementation of SI units has become mandatory with a transition period of about ten years. Some of the journals have already adopted the SI units and any material sent for publication to them must use only these. International Commission on Radiation Units and Measurement (ICRU) published letters in several journals including Physics in Medicine and Biology, Health Physics, British Journal of Radiology, etc. outlining the latest recommendations on SI units to elicit the reactions of scientists in the general field of radiological sciences. Reactions to the letters were numerous as can be seen in the correspondence columns of these journals for the last few years and ranged from great misgivings and apprehension to support and appreciation. SI units have also been the subject of editorial comments in several journals. On the basis of a survey of this literature, it may be said that there was general agreement on the long term advantage of SI units inspite of some practical difficulties in their use particularly in the initial stages. This report presents a review of SI units in radiological sciences with a view to familiarize the users with the new units in terms of the old. A time table for the gradual changeover to the SI units is also outlined. (auth.)

  4. Wallada Bint al Mustakfi entre dos culturas

    shreen Mahmoud Al Refai

    2013-10-01

    Full Text Available La princesa cordobesa Wallada Bint al Mustakfi bil-lah, hija del califa al Mustakfi Muhammad Ibn Abdel Rahman Ibn Obaidil-lah Ibn Al Nasir lidin Al-lah era una poetisa estimable, a quien los grandes poetas no podían superar. Era una mujer única, guapa y decente. Mantenía una relación sentimental con el  poeta y visir Ibn Zaydún. Dicha pasión, narrada por los poemas escritos por ambos amantes, se terminó por la separación debida a los celos, también de ambos;  al poeta le gustó la voz de una esclava de la princesa. Eso dio rabia a la última. Movido también por los celos, Ibn Zaydún dedicó una epístola satírica al visir Ibn Abdús, que estaba enamorado de Wallada. Tal hecho también irritó a la princesa. A pesar de tener amantes y admiradores, Wallada murió sin casarse al  día 2 de safar de 480 (o 484 de la Híjira pasando los ochenta años Me han llamado la atención el carácter tan culto, independiente y liberal de aquella mujer, su relación amorosa con Ibn Zaydún que no acabó felizmente y los muchos años que vivió sin casasre. Parece que la vida de la princesa hispano-musulmana llamó también la atención de muchos escritores árabes y españoles. Prueba de ello son varias obras literarias escritas en árabe y en español sobre Wallada e Ibn Zaydún. Por consiguiente, me resulta muy interesante realizar un estudio comparativo sobre este tema averiguando si, o no, la diferencia de culturas influiría en las opiniones  de los autores sobre la vida sentimental de aquella poetisa cordobesa.

  5. Thermal stability of Nb-Si-N and Ta-Si-N as diffusion barriers between Cu and Si

    In this study, Nb-Si-N and Ta-Si-N films were deposited on (100)Si wafers using a reactive sputtering technique and their thermal stability indispensable for a barrier metal against Cu was investigated using sheet resistance measurement, X-ray diffraction, and Auger electron spectroscopy depth profiling. The N2/Ar gas flow ratio for the sputter deposition of the Nb-Si-N and Ta-Si-N films with the highest thermal stability were found to be 5 % and 15 %, respectively. The Nb-Si-N film failed at 700 .deg. C, while the Ta-Si-N film failed at 900 .deg. C. the failure mechanism of the Nb-Si-N was found to be as follows : Cu atoms move to the Nb-Si-N/Si interface through the Nb-Si-N film and react with Si atoms in the Si substrate resulting in the formation of Cu3Si at the Nb-Si-N/Si interface. Also the failure mechanism of Ta-Si-N was found to be nearly the same as that of Nb-Si-N

  6. Low loss Si(3)N(4)-SiO(2) optical waveguides on Si.

    Henry, C H; Kazarinov, R F; Lee, H J; Orlowsky, K J; Katz, L E

    1987-07-01

    We have developed an optical integrated circuit waveguide technology based on conventional Si processing. We demonstrate waveguide losses of <0.3 dB/cm in the 1.3-1.6-microm wavelength range. We use a high refractive-index core of Si(3)N(4) surrounded by SiO(2) cladding layers, which provides a highly confined optical mode adequate for butt coupling to channel substrate buried heterostructure lasers. We report the first IR transmission experiments in these waveguides and find two absorption peaks associated with H in SiO(2) and Si(3)N(4) layers at 1.40 and 1.52 microm, respectively. The peak absorptions are 2.2 and 1.2 dB/cm, respectively, and these peaks can be largely removed by annealing at 1100-1200 degrees C. PMID:20489931

  7. Effect of hydrogen on passivation quality of SiNx/Si-rich SiNx stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

    We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiNx/Si-rich SiNx stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 1012 cm−2, which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiNx films deposited with H2 dilution show better passivation quality of SiNx/Si-rich SiNx stacked layers than those prepared without H2 dilution. Effective minority carrier lifetime (τeff) in c-Si passivated by SiNx/Si-rich SiNx stacked layers is as high as 5.1 ms when H2 is added during Si-rich SiNx deposition, which is much higher than the case of using Si-rich SiNx films prepared without H2 dilution showing τeff of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiNx/SiNx stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H2 gas during Si-rich SiNx film deposition greatly enhances effective minority carrier lifetime (τeff). • For a Si-rich SiNx film with refractive index of 2.92, τeff improves from 3.3 to 5.1 ms by H2 addition

  8. Fabrication and evaluation of propagation loss of Si/SiGe/Si photonic-wire waveguides for Si based optical modulator

    We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs for Si-based optical modulators. The Si (80 nm)/Si0.72Ge0.28 (40 nm) layers grown on Si-on-insulator by molecular beam epitaxy for optical modulators were evaluated by in-situ reflection high-energy electron diffraction, atomic force microscope, X-ray diffraction and Raman spectroscopy, exhibiting that the fully-strained highly-crystalline SiGe layer was obtained. We have evaluated the propagation loss of the Si/strained SiGe/Si photonic-wire waveguides. The wavelength dependence of the propagation loss exhibits the bandgap narrowing of the strained Si0.72Ge0.28, while the optical absorption of the strained Si0.72Ge0.28 is not significant for the optical modulator application at 1.55-μm wavelength. - Highlights: • We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs. • The Si/Si0.72Ge0.28 grown on Si-on-insulator were evaluated to be fully strained. • We have fabricated and evaluated the Si/strained SiGe/Si photonic-wire waveguides. • The wavelength dependence exhibits bandgap narrowing of the strained Si0.72Ge0.28. • Optical absorption of the SiGe is not significant for optical modulators at 1.55 μm

  9. Relaciones entre calidad de vida, actividad física, sedentarismo y fitness cardiorrespiratorio en niños

    Pere Palou

    2012-01-01

    Full Text Available El objetivo de este estudio fue explorar la relación entre algunos dominios de la calidad de vida, relacionada con la salud (CVRS en niños, con el estado cardiorrespiratorio, el nivel de actividad física, el sedentarismo (tiempo de pantalla y el índice de masa corporal de una población de 302 niños de once y doce años de edad, para determinar si la condición física (Fitness cardiorrespiratorio es un factor clave en lugar de la actividad física, para garantizar la futura calidad de vida de los niños. El cuestionario sobre salud infantil y calidad de vida (CHIP-CE / PRF- edición española se utilizó para medir la CVRS, El test de 20m de ida y vuelta para el fitness cardiorrespiratorio, El cuestionario de Salud Escolar de Acción, Planificación y Evaluación (SHAPES, módulo de actividad física, se utilizó para medir la actividad física semanal y el tiempo de pantalla. Los padres reportaron altura y peso. Los resultados muestran una fuerte correlación entre el fitness cardiovascular y la CVRS, y el tiempo de pantalla con la CVRS, pero no existe correlación entre CVRS y la actividad física.

  10. Nitric acid oxidation of Si (NAOS) method for low temperature fabrication of SiO2/Si and SiO2/SiC structures

    We have developed low temperature formation methods of SiO2/Si and SiO2/SiC structures by use of nitric acid, i.e., nitric acid oxidation of Si (or SiC) (NAOS) methods. By use of the azeotropic NAOS method (i.e., immersion in 68 wt% HNO3 aqueous solutions at 120 deg. C), an ultrathin (i.e., 1.3-1.4 nm) SiO2 layer with a low leakage current density can be formed on Si. The leakage current density can be further decreased by post-metallization anneal (PMA) at 200 deg. C in hydrogen atmosphere, and consequently the leakage current density at the gate bias voltage of 1 V becomes 1/4-1/20 of that of an ultrathin (i.e., 1.5 nm) thermal oxide layer usually formed at temperatures between 800 and 900 deg. C. The low leakage current density is attributable to (i) low interface state density, (ii) low SiO2 gap-state density, and (iii) high band discontinuity energy at the SiO2/Si interface arising from the high atomic density of the NAOS SiO2 layer. For the formation of a relatively thick (i.e., ≥10 nm) SiO2 layer, we have developed the two-step NAOS method in which the initial and subsequent oxidation is performed by immersion in ∼40 wt% HNO3 and azeotropic HNO3 aqueous solutions, respectively. In this case, the SiO2 formation rate does not depend on the Si surface orientation. Using the two-step NAOS method, a uniform thickness SiO2 layer can be formed even on the rough surface of poly-crystalline Si thin films. The atomic density of the two-step NAOS SiO2 layer is slightly higher than that for thermal oxide. When PMA at 250 deg. C in hydrogen is performed on the two-step NAOS SiO2 layer, the current-voltage and capacitance-voltage characteristics become as good as those for thermal oxide formed at 900 deg. C. A relatively thick (i.e., ≥10 nm) SiO2 layer can also be formed on SiC at 120 deg. C by use of the two-step NAOS method. With no treatment before the NAOS method, the leakage current density is very high, but by heat treatment at 400 deg. C in pure hydrogen, the

  11. Nitric acid oxidation of Si (NAOS) method for low temperature fabrication of SiO{sub 2}/Si and SiO{sub 2}/SiC structures

    Kobayashi, H., E-mail: koba771@ybb.ne.jp [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Imamura, K.; Kim, W.-B.; Im, S.-S.; Asuha [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2010-07-15

    We have developed low temperature formation methods of SiO{sub 2}/Si and SiO{sub 2}/SiC structures by use of nitric acid, i.e., nitric acid oxidation of Si (or SiC) (NAOS) methods. By use of the azeotropic NAOS method (i.e., immersion in 68 wt% HNO{sub 3} aqueous solutions at 120 deg. C), an ultrathin (i.e., 1.3-1.4 nm) SiO{sub 2} layer with a low leakage current density can be formed on Si. The leakage current density can be further decreased by post-metallization anneal (PMA) at 200 deg. C in hydrogen atmosphere, and consequently the leakage current density at the gate bias voltage of 1 V becomes 1/4-1/20 of that of an ultrathin (i.e., 1.5 nm) thermal oxide layer usually formed at temperatures between 800 and 900 deg. C. The low leakage current density is attributable to (i) low interface state density, (ii) low SiO{sub 2} gap-state density, and (iii) high band discontinuity energy at the SiO{sub 2}/Si interface arising from the high atomic density of the NAOS SiO{sub 2} layer. For the formation of a relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer, we have developed the two-step NAOS method in which the initial and subsequent oxidation is performed by immersion in {approx}40 wt% HNO{sub 3} and azeotropic HNO{sub 3} aqueous solutions, respectively. In this case, the SiO{sub 2} formation rate does not depend on the Si surface orientation. Using the two-step NAOS method, a uniform thickness SiO{sub 2} layer can be formed even on the rough surface of poly-crystalline Si thin films. The atomic density of the two-step NAOS SiO{sub 2} layer is slightly higher than that for thermal oxide. When PMA at 250 deg. C in hydrogen is performed on the two-step NAOS SiO{sub 2} layer, the current-voltage and capacitance-voltage characteristics become as good as those for thermal oxide formed at 900 deg. C. A relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer can also be formed on SiC at 120 deg. C by use of the two-step NAOS method. With no treatment before the NAOS method

  12. The production and growth of monocrystalline Si/CoSi2/Si heterostructures after high dose ion implantation

    CoSi2 is a favourable candidate for low ohmic interconnects in integrated circuits with high temperature stability. Its CaF2 structure is very similar to the diamond structure of Si with a lattice mismatch of only -1.2%. This allows epitaxial growth of Si/CoSi2/Si heterostructures required for three dimensional device applications. High dose Co+ implantation with subsequent annealing is a valuable method to form buried epitaxial CoSi2 layers with sharp interfaces both in (111)- and (100)-Si. The excellent crystalline quality of the surface Si layer enables the epitaxial growth of an additional Si layer to bury the silicide layer deeper into the substrate. Buried CoSi2 lines of several microns width were fabricated by implanting the Co+ ions through a thermally grown SiO2 mask patterned by photolithography. Both steps are necessary for the application of ion beam synthesis to microelectronics. (orig./BHO)

  13. Organic thin film transistors with a SiO2/SiNx/SiO2 composite insulator layer

    Liu Xiang; Liu Hui

    2011-01-01

    We have investigated a SiO2/SiNx/SiO2 composite insulation layer structured gate dielectric for an organic thin film transistor (OTFT) with the purpose of improving the performance of the SiO2 gate insulator.The SiO2/SiNx/SiO2 composite insulation layer was prepared by magnetron sputtering.Compared with the same thickness of a SiO2 insulation layer device,the SiO2/SiNx/SiO2 composite insulation layer is an effective method of fabricating OTFT with improved electric characteristics and decreased leakage current.Electrical parameters such as carrier mobility by field effect measurement have been calculated.The performances of different insulating layer devices have been studied,and the results demonstrate that when the insulation layer thickness increases,the off-state current decreases.

  14. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl2/Si powder source

    Meng, Erchao; Ueki, Akiko; Meng, Xiang; Suzuki, Hiroaki; Itahara, Hiroshi; Tatsuoka, Hirokazu

    2016-08-01

    Si nanosheets connected to Si nanowires were synthesized using a MnCl2/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH4 or SiCl4. The existence of the Si nanosheets connected to the Si nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.

  15. Si Isotopes of Brownleeite

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  16. AMPLEX-SiCAL

    This paper reports on an analog signal processor using commercial 3 μm CMOS technology which has been designed and produced for the silicon luminosity calorimeter SiCAL of the ALEPH experiment. This processor is a modified version of the AMPLEX integrated circuit designed for the inner silicon detector of the UA-2 experiment. The output voltage swing has been increased to more than 5.5 Volt as required for the large dynamic range of 1000 MIPs or 3.8 pC2. A fast analog summation, based on a neural network principle called follower aggregation, computes the average input charges for triggering purposes. The chip contains 16 channels, with a charge amplifier, shaper, track-and-hold stage, multiplexer, fast analog sum and a calibration system. The power consumption of the overall chip is 100 mW. The equivalent noise charge is less than 0.13MIP (0.5 fC rms) for a 50 pF detector capacitance, and the peaking time is about 250ns

  17. Fabrication and characterization of CuxSi1-x films on Si (111) and Si (100) by pulsed laser deposition

    Zhang, Song; Wu, Jun; He, Zhiqiang; Xie, Jun; Lu, Jingqi; Tu, Rong; Zhang, Lianmeng; Shi, Ji

    2016-05-01

    The CuxSi1-x thin films have been successfully fabricated by pulsed laser deposition (PLD). The influences of laser energy fluency (I0) and deposition temperature (Td) on the phase structure were investigated. The results show that Cu deposited on Si (001) at I0 = 0.5-2.0 J/cm2, and η"-Cu3Si formed on Si (111) at I0 = 1.0-2.0 J/cm2. The films were consisted of Cu, η'-Cu3Si, ɛ-Cu15Si4 and δ-Cu0.83Si0.17 at Td = 100-500 °C on Si (001). The films were the single phase of η-Cu3Si at Td = 700 °C. In the case of Si (111), the phase structures transformed from Cu to Cu + η'-Cu3Si to η'-Cu3Si to η'-Cu3Si + η-Cu3Si with the increasing of Td. Rectangular grains were formed on Si (001), whereas triangular grains on Si (111). Cu (001) film was epitaxially grown on Si (001) at I0 = 1.5 J/cm2 and Td = 20 °C. η-Cu3Si (001) epitaxial layer was formed on Si (111) at I0 = 1.5 J/cm2 and Td = 700 °C. The epitaxial relationships of Cu (001)[100]//Si (001)[110] and η-Cu3Si (001)[-110]//Si (111)[11-2] were identified.

  18. Estudio experimental de la inducción electromagnética entre dos bobinas: Dependencia con la corriente eléctrica

    Villalba Montoya, José Manuel; Ferreira, Luciana; Arribas Garde, Enrique; Nájera López, Alberto; Beléndez Vázquez, Augusto

    2014-01-01

    En este artículo se muestran un conjunto de sencillas experiencias de laboratorio que ilustran el fenómeno de la inducción electromagnética. El dispositivo experimental, análogo a un transformador, está formado por dos bobinas magnéticamente acopladas conectadas a un generador de corriente alterna sinusoidal de frecuencia variable. Midiendo la tensión inducida en la bobina del secundario en función de la corriente que hay en la bobina del primario se obtiene una dependencia lineal. Los result...

  19. Radiation emission from wrinkled SiGe/SiGe nanostructure

    Fedorchenko, Alexander I.; Cheng, H. H.; Sun, G.; Soref, R. A.

    2010-01-01

    Roč. 96, č. 11 (2010), s. 113104-113107. ISSN 0003-6951 Institutional research plan: CEZ:AV0Z20760514 Keywords : SiGe wrinkled nanostructures * si-based optical emitter * synchrotron radiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.820, year: 2010 http:// apl .aip.org/resource/1/applab/v96/i11/p113104_s1?isAuthorized=no

  20. Nonlinear Modeling of Si/SiGe HBT Using ANN

    Taher, H.; Schreurs, D; Vestiel, E.; Gillon, R; Nauwelaers, B.

    2004-01-01

    We present a large signal model for Si/SiGe HBTs using an Artificial Neural Network (ANN). The ANN is used to model the DC non-linearities of the intrinsic device. In this way, physical phenomena such as nonideal leakage currents and the Kirk effect can be modeled without time-consuming extraction. Capacitive nonlinearities are modeled by the well-known relationship between the capacitance and the junction voltage, ignoring the diffusion capacitance. By comparing ANN mode...

  1. Low-loss rib waveguides containing Si nanocrystals embedded in SiO2

    Pellegrino, Paolo; Garrido Fernández, Blas; García Favrot, Cristina; Arbiol i Cobos, Jordi; Morante i Lleonart, Joan Ramon; Melchiorri, Mirko; Daldosso, Nicola; Pavesi, Lorenzo; Scheid, E; Sarrabayrouse, G.

    2005-01-01

    We report on the study and modeling of the structural and optical properties of rib-loaded waveguides working in the 600-900-nm spectral range. A Si nanocrystal (Si-nc) rich SiO2 layer with nominal Si excess ranging from 10% to 20% was produced by quadrupole ion implantation of Si into thermal SiO2 formed on a silicon substrate. Si-ncs were precipitated by annealing at 1100°C, forming a 0.4-um-thick core layer in the waveguide. The Si content, the Si-nc density and size, the Si-nc emission, a...

  2. SiC表面处理对Si3N4-SiC材料显微结构的影响%Influence of SiC Surface Treatment on Microstructure of Si3N4-SiC

    黎军

    2004-01-01

    在用反应烧结法制备Si3N4结合SiC复合材料时,如在反应前对SiC原料进行高温表面处理,可使SiC颗粒表面生成一层SiO2氧化层,该氧化层在高温、氮气气氛中会生成Si3N4颗粒或纤维,从而有效连接各SiC颗粒.

  3. ENTRE DOS INTEMPERIES. APUNTES SOBRE LAS RELACIONES ENTRE EL FORO Y EL MERCADO

    Antonio Armesto Aira

    2010-05-01

    Full Text Available RESUMEN Este ensayo encadena tres niveles. En el primero, de la pregunta por la utilidad genuina de la arquitectura, definida en los orígenes, se deriva que la arquitectura preserva la vida de dos clases de intemperie: de la intemperie física, procurando un equilibrio con el medio (homeostasis y de la intemperie moral procurando orientación espacio temporal. Esta doble utilidad la cumplen y la expresan unos utensilios concretos y universales, formas necesarias y objetivas, no arbitrarias, arquetipos que fundan la tradición de las formas propias de la arquitectura en la historia. El êthos de la humanidad, cuyo núcleo es la conciencia, para constituirse tomará de la formalidad de estos utensilios su propia sustancia formal, desde el momento en que con ellos es capaz de conjurar el tiempo destructor de la vida (meteorológico y cronológico – un tiempo discontinuo–, y exorcizar el espacio amorfo –un espacio continuo– y desorientador de la naturaleza. Esos utensilios forman un relieve tectónico, superpuesto al de la naturaleza otorgada, al que llamamos paisaje.En el segundo nivel se descubre que la estructura de ese paisaje reposa sobre la similitud entre estas formas objetivas y los caracteres del mercado y del foro que se corresponden, respectivamente, con la idea de homeostasis y con la de orientación.En el tercer nivel se estudian las modalidades de relación entre foro y mercado con el objeto de hallar instrumentos para hacer la crítica del presente. El criterio principal es que foro y mercado deben mantener en la realidad una relación dialógica (conservar su contradicción o composición y no dialéctica pues una síntesis superadora entre ellos, cuando se da, conlleva un decaimiento de la formalidad de la conciencia, menoscaba el êthos de la humanidad y produce la quiebra ética del paisaje.SUMMARYThis essay encompasses three levels. The first, on the question of the genuine utility of architecture, defined in the origins

  4. Nitriding kinetics of Si-SiC powder mixtures as simulations of reaction bonded Si3N4-SiC composites

    Lightfoot, A.; Sheldon, B. W.; Flint, J. H.; Haggerty, J. S.

    1989-01-01

    The nitriding kinetics of Si and Si plus SiC powder mixtures were studied to simulate the fabrication of RBSN-SiC ceramic matrix composites. Very clean, assynthesized, and solvent-exposed powders were studied; C-rich and Si-rich SiC 0.04-0.05 micron diameter powders were mixed in varying concentrations with SiH4-derived 0.2-0.3 micron diameter Si powder. Complete nitridation is achieved with C-rich SiC powders in 140 min at 1250 C, and in the centers of Si-rich SiC powders in 15 min. The effects on the incubation periods, fast reaction periods, and slow reaction periods that characterize these nitriding processes were studied to explain unusual reverse reaction gradients and other effects of contamination.

  5. On the line intensity ratios of prominent Si II, Si III, and Si IV multiplets

    Djeniže, S.; Srećković, A.; Bukvić, S.

    2010-01-01

    Line intensities of singly, doubly and triply ionized silicon (Si II, Si III, and Si IV, respectively) belonging to the prominent higher multiplets, are of interest in laboratory and astrophysical plasma diagnostics. We measured these line intensities in the emission spectra of pulsed helium discharge. The Si II line intensity ratios in the 3 s3 p22D-3 s24 p2Po, 3 s23 d2D-3 s24 f2Fo, and 3 s24 p2Po-3 s24 d2D transitions, the Si III line intensity ratios in the 3 s3 d3D-3 s4 p3Po, 3 s4 p3Po-3 s4 d3D, 3 s4 p3Po-3 s5 s3S, 3 s4 s3S-3 s4 p3Po, and 3 s4 f3Fo-3 s5 g3G transitions, and the Si IV line intensity ratios in the 4 p2Po-4 d2D and 4 p2Po-5 s2S transitions were obtained in a helium plasma at an electron temperature of about 17,000 ± 2000 K. Line shapes were recorded using a spectrograph and an ICCD camera as a highly-sensitive detection system. The silicon atoms were evaporated from a Pyrex discharge tube designed for the purpose. They represent impurities in the optically thin helium plasma at the silicon ionic wavelengths investigated. The line intensity ratios obtained were compared with those available in the literature, and with values calculated on the basis of available transition probabilities. The experimental data corresponded well with line intensity ratios calculated using the transition probabilities obtained from a Multi Configuration Hartree-Fock approximation for Si III and Si IV spectra. We recommend corrections of some Si II transition probabilities.

  6. Dimensionless Units in the SI

    Mohr, Peter J

    2014-01-01

    The International System of Units (SI) is supposed to be coherent. That is, when a combination of units is replaced by an equivalent unit, there is no additional numerical factor. Here we consider dimensionless units as defined in the SI, {\\it e.g.} angular units like radians or steradians and counting units like radioactive decays or molecules. We show that an incoherence may arise when different units of this type are replaced by a single dimensionless unit, the unit "one", and suggest how to properly include such units into the SI in order to remove the incoherence. In particular, we argue that the radian is the appropriate coherent unit for angles and that hertz is not a coherent unit in the SI. We also discuss how including angular and counting units affects the fundamental constants.

  7. Polymer-derived micro-nano-structured Si3N4/SiC-composites

    Micro-nano-structured Si3N4/SiC-composites were prepared by liquid phase sintering of either amorphous, polymer derived Si-C-N powder or SiC1+x coated α-Si3N4 powder, followed by gas pressure sintering. The obtained microstructures were investigated by scanning and transmission electron microscopy (SEM, TEM). Nanosized SiC inclusions embedded in microcrystalline Si3N4 grains were analyzed by elemental mapping with electron spectroscopic imaging (ESI)

  8. Divergência entre genótipos de soja, cultivados em várzea irrigada

    Elonha Rodrigues dos Santos

    2011-12-01

    Full Text Available A divergência genética é um dos mais importantes parâmetros avaliados por melhoristas de plantas, na fase inicial de um programa de melhoramento genético. Diante disso, objetivou-se com este trabalho avaliar, por meio de técnicas multivariadas, a divergência genética entre 48 genótipos de soja, cultivados em várzea irrigada no Estado do Tocantins, com o intuito de identificar as combinações mais promissoras para produzir recombinações superiores, tanto destinados a produção de óleo e farelo, como do grupo especial, destinados ao consumo humano. O experimento foi conduzido no município de Formoso do Araguaia, TO, em cultivo de várzea irrigada na entressafra de 2010. O delineamento experimental foi o de blocos ao acaso, com quatro repetições. Verificou-se variabilidade entre os genótipos testados. Os resultados dos métodos de agrupamento de Tocher, UPGMA e Variáveis Canônicas foram concordantes entre si e detectaram quatro grupos distintos. As seguintes hibridações são promissoras para produção de grãos de soja destinados a óleo e farelo: M-Soy 8766, M-Soy 9144, A 7002 e M-Soy 9056 com Amaralina e cruzamentos entre M-Soy 8766, M-Soy 9144 e Amaralina com BRSMG 790A, BRS 257, BRS 216 e BRS 213 e são indicados visando a genótipos de soja especiais para alimentação humana.

  9. Modification of potential of the silicon surface under ion plasma treatment of Si*-SiO2-Si structures

    A charging effect is studied during ion-chemical etching and ion alloying of Si*-SiO2-Si, SiO2-Si structures as well as the effect of distorted layer formation under ion treatment of monocrystalline (Si) and polycrystalline (Si*) silicon. The modification of material layers charging is investigated using test structures. The given technique is applied to detect the depth of distorted layers and the potential of silicon composition films through changes of test structure parameters on ion processing

  10. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    Jiehua Li; Hage, Fredrik S.; Xiangfa Liu; Quentin Ramasse; Peter Schumacher

    2016-01-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles...

  11. Si me das a elegir

    Spiga, Claudio

    2012-01-01

    El debate por la despenalización de la marihuana ocupa a diez gobiernos americanos. Como en la versión cannábica de "La cucaracha", el presente canta una puesta al día entre las leyes y la realidad.

  12. Redundância entre métricas da qualidade ambiental de riachos em paisagem agrícola

    Marcel Okamoto Tanaka

    2015-11-01

    Full Text Available Indicadores ambientais são amplamente usados para avaliação da qualidade dos corpos d’água. Como o monitoramento envolve alto custo de amostragem, e a construção de índices multimétricos pressupõe métricas não correlacionadas, este estudo avaliou se havia correlação entre métricas que caracterizam o uso e cobertura do solo, composição da zona ripária e estrutura da floresta, bem como correlações entre indicadores das comunidades de macroinvertebrados e peixes. O estudo foi feito em 12 afluentes de baixa ordem dos rios Jacaré-Pepira e Jacaré-Guaçu, formando um gradiente de estresse ambiental no estado de São Paulo. Não houve correlação entre as métricas relacionadas ao uso e cobertura do solo, e apenas a proporção de pastos foi negativamente correlacionada com algumas métricas da estrutura da floresta ripária. Assim, tanto as informações do uso e cobertura do solo quanto sobre a composição da zona ripária e estrutura das florestas podem ser importantes na avaliação ambiental de riachos. As métricas relacionadas às comunidades de macroinvertebrados foram correlacionadas entre si, assim como a maioria das métricas relacionadas às comunidades de peixes. Estudos propondo índices multimétricos não encontraram correlação entre estas variáveis, mas avaliaram riachos em situações extremas (preservados vs. impactados, sendo os riachos impactados influenciados por diferentes condutores de degradação, o que pode resultar em respostas distintas das comunidades biológicas. Os resultados deste estudo sugerem que o desenvolvimento de índices deve ser bastante específico para cada região estudada, e que muitas vezes as avaliações são feitas em relação a condutores de impactos específicos, que podem variar entre diferentes sistemas.

  13. Mejora de la comunicación entre Atención Primaria y Atención Especializada con una Historia Clínica Electrónica compartida.

    Elviro Bodoy, Tirso; Escolar Castellón, Fernando; Martínez-Berganza Asensio, Alberto Jerónimo Santiago

    2009-01-01

    El trabajo describe un sistema de comunicación informatizada, entre los médicos de atención primaria del Centro de Salud y un centro de especialistas ubicados en el mismo centro de salud utilizando la misma historia clínica informatizada. Esta historia clínica electrónica compartida mejora la comunicación entre Atención Primaria y Especializada si las derivaciones se hacían a través del mismo sistema de información. -Los porcentajes de los niveles de cumplimentación tanto de envío de informa...

  14. RELACIÓN ENTRE LA INGESTA NUTRICIONAL Y EL RENDIMIENTO FÍSICO EN LOS ATLETAS PARTICIPANTES EN EL TRIATLÓN DEL COCO DEL AÓO 2002 EN COSTA RICA

    Mónica Umaña Alvarado; José Moncada Jiménez

    2002-01-01

    La investigación estudió las posibles relaciones entre el consumo de carbohidratos (CHO) antes y durante una competencia de triatlón y el rendimiento, y variación en la glicemia de los participantes. También se determinó si existían diferencias entre la ingesta de alimentos de los deportistas que presentaron síntomas gastrointestinales y los que no los presentaron. En el estudio participaron 36 triatlonistas (4 mujeres y 32 hombres), todos finalizaron la competencia. Se midió la glicemia y el...

  15. Relação entre estressores, estresse e ansiedade

    Margis Regina

    2003-01-01

    Full Text Available Os autores apresentam uma breve revisão de literatura sobre a relação entre ansiedade, eventos estressores e estresse. São descritas as diferentes situações estressoras, a definição de evento de vida estressor e os aspectos cognitivos, comportamentais e fisiológicos da resposta frente ao estresse. A neuroanatomia e os principais neurotransmissores envolvidos na resposta fisiológica de ansiedade ao estresse são descritos. Estudos genéticos que evidenciam a relação entre os eventos de vida estressores como fator de risco para ansiedade são apresentados. A relação causal entre os eventos de vida estressores e o aparecimento de ansiedade é abordada a partir de estudos realizados com adultos e adolescentes.

  16. Detección de perfiles cognitivos mediante WISC-IV en niños diagnosticados de TDAH: ¿Existen diferencias entre subtipos?

    Javier Fenollar-Cortés

    2015-01-01

    Full Text Available El presente estudio explora si se puede obtener un perfil cognitivo específico para niños/as con TDAH a partir de la Escala de Inteligencia Wechsler para Niños Cuarta Edición (WISC-IV, y si ese perfil es capaz de diferenciar entre los subtipos clínicos de TDAH. Se seleccionó un grupo de control de 47 niños/as y otro grupo clínico de 86 niños/as diagnosticados/as con TDAH, éste último dividido a su vez en dos subgrupos de acuerdo a sus características clínicas. El grupo clínico se caracterizó por una puntuación ICG>ICC respecto al grupo de control. Los subgrupos clínicos no obtuvieron puntuaciones significativamente diferentes en ninguno de los índices, pero sí lo hicieron respecto a la distancia entre el Índice de Memoria de Trabajo y el Índice de Velocidad de Procesamiento. Para el subgrupo TDAH predominantemente inatento esta distancia fue positiva, mientras que para el subgrupo TDAH-combinado fue negativa. Estos resultados aportan evidencia empírica a la hipótesis de la existencia de un perfil cognitivo específico del TDAH, con potencial para discriminar entre subtipos clínicos de TDAH.

  17. SiC-SiC and C-SiC Honeycomb for Advanced Flight Structures Project

    National Aeronautics and Space Administration — The proposed project builds upon the work done in Phase I with the development of a C-SiC CMC honeycomb material that was successfully tested for mechanical...

  18. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    Li, Jiehua; Hage, Fredrik S.; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  19. Convergencia de normas contables internacionales entre México y Estados Unidos: evidencia empírica

    Sergio Demetrio Polo Jiménez

    2015-12-01

    Full Text Available El objetivo de este trabajo es examinar si la adaptación de la normativa contable mexicana a las IFRS ha convertido los principios mexicanos en unas normas de mayor calidad, incrementando su comparabilidad con los US GAAP y reduciendo la manipulación de los resultados. A su vez, nos cuestionamos, de acuerdo con la Teoría de la Agencia, si las diferencias entre las variables contables calculadas bajo la normativa mexicana y americana pueden ser debidas a la interpretación oportunista de los estándares mexicanos por los managers más que a las diferencias en la normativa contable de ambos países. Los resultados sugieren que los esfuerzos para converger las normas contables han incrementado la comparabilidad del resultado contable, si bien esta convergencia se debe también al uso oportunista de la elección de los métodos contables en función de la distinta coyuntura económica.

  20. Arquitectura de comunicación entre frameworks jadesymfony

    RODRÍGUEZ C., PAOLA J.; GÓMEZ R., SANTIAGO

    2009-01-01

    La inclusión del uso de Agentes dentro del campo del desarrollo de software es una de las principales áreas de estudio en la actualidad. Específicamente, el desarrollo de aplicaciones Web que aprovechen las ventajas que ofrece la tecnología de agentes y en especial las distintas propuestas de comunicación entre frameworks son esfuerzos importantes dentro de este campo. En este sentido, este artículo describe una arquitectura de comunicación entre dos de los principales frameworks de desarroll...

  1. ¿Relaciones entre metafísica y arte?

    Vélez León, Paulo

    2013-01-01

    [ES] En el presente trabajo nos proponemos hacer visible una posible relación entre metafísica y arte, a partir del presupuesto de que, en cuanto absolutos son lo mismo; es así que, aquello que digamos de la metafísica es válido para el arte. Sin embargo, la distinción entre metafísica y arte no es factible de evidenciar en el mundo, en especial en un acontecimiento artístico, como por ejemplo una muestra o concierto, sino por las distinciones del mundo. Esta cuestión intentaremos abordarla d...

  2. Relação entre estressores, estresse e ansiedade

    Margis Regina; Picon Patrícia; Cosner Annelise Formel; Silveira Ricardo de Oliveira

    2003-01-01

    Os autores apresentam uma breve revisão de literatura sobre a relação entre ansiedade, eventos estressores e estresse. São descritas as diferentes situações estressoras, a definição de evento de vida estressor e os aspectos cognitivos, comportamentais e fisiológicos da resposta frente ao estresse. A neuroanatomia e os principais neurotransmissores envolvidos na resposta fisiológica de ansiedade ao estresse são descritos. Estudos genéticos que evidenciam a relação entre os eventos de vida estr...

  3. Prospective crystallization of amorphous Si films for new Si TFTs

    Noguchi, Takashi [University of the Ryukyus, Fuculty of Engineering, Nishihara, Okinawa (Japan)

    2008-07-01

    Prospective crystallization results of amorphous silicon film are reviewed and are discussed. Silicon TFTs are playing an important role for Active-Matrix Flat Panel Displays (AM-FPD) based on amorphous or poly-Si thin-film transistors (TFTs). Poly-Si TFTs provide a possibility to develop highly functional system on pane (SoP) applications. In order to get a high performance TFT, large poly-crystal grains or high cystallinity for the film is required. Two basic crystallization techniques namely solid phase crystallization (SPC) and excimer laser crystallization (ELC) are reviewed and relating issues are described. A grain growth technique has been developed based on the two crystallization techniques, so far. In order to mount a poly-Si TFT system on a flexible panel such as a plastic, an excimer laser of UV pulse beam has an advantage for the TFT channel as well as for the source and drain contacts as a ultra-low temperature poly-Si (U-LTPS) process. To realize a high performance TFT of uniform and high carrier mobility, location control crystallization had been proposed. Some of the distinctive results for crystal orientation control of (100) and (111) face using the laser crystallization techniques are described. In the future, single-crystalline Si TFT of a functional 3D structure is expected to realize an advanced SoP for ubiquitous electronics era. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Simulations and experiments of SiC heteroepitaxial growth on Si(001) surface

    Kitabatake, Makoto; Deguchi, Masahiro; Hirao, Takashi

    1993-10-01

    Mechanism of SiC heteroepitaxial growth by the carbonization of the Si(001) surface was studied at the atomic scale using molecular dynamics (MD) simulations and molecular beam epitaxy (MBE) experiments. Heteroepitaxial growth of single crystal 3c-SiC on the Si(001) surface (3c-SiC[001]∥Si[001] and 3c-SiC[110]∥Si[110]) was observed in both the MD simulations and MBE experiments. Breaking of the Si—Si bonds and shrinkage of the [110] Si rows with C atoms are possible mechanisms for the heteroepitaxial growth of SiC on Si(001). Microscopic structures and mechanisms of the twin formations and pit formations are discussed. Ultraviolet light irradiation is proposed and confirmed to enhance the epitaxial growth of SiC in the MBE experiments.

  5. Construction and characterization of spherical Si solar cells combined with SiC electric power inverter

    Oku, Takeo; Matsumoto, Taisuke; Hiramatsu, Kouichi; Yasuda, Masashi; Shimono, Akio; Takeda, Yoshikazu; Murozono, Mikio

    2015-02-01

    Spherical silicon (Si) photovoltaic solar cell systems combined with an electric power inverter using silicon carbide (SiC) field-effect transistor (FET) were constructed and characterized, which were compared with an ordinary Si-based converter. The SiC-FET devices were introduced in the direct current-alternating current (DC-AC) converter, which was connected with the solar panels. The spherical Si solar cells were used as the power sources, and the spherical Si panels are lighter and more flexible compared with the ordinary flat Si solar panels. Conversion efficiencies of the spherical Si solar cells were improved by using the SiC-FET.

  6. Synthesis and properties of Si and SiGe/Si nanowires

    Redwing, Joan M.; Lew, Kok-Keong; Bogart, Timothy E.; Pan, Ling; Dickey, Elizabeth C.; Carim, A. H.; Wang, Yanfeng; Cabassi, Marco A.; Mayer, Theresa S.

    2004-06-01

    The fabrication of semiconductor nanowires, in which composition, size and conductivity can be controlled in both the radial and axial direction of the wire is of interest for fundamental studies of carrier confinement as well as nanoscale device development. In this study, group IV semiconductor nanowires, including Si, Ge and SixGe1-x alloy nanowires were fabricated by vapor-liquid-solid (VLS) growth using gaseous precursors. In the VLS process, gold is used to form a liquid alloy with Si and Ge which, upon supersaturation, precipitates a semiconductor nanowire. Nanoporous alumina membranes were used as templates for the VLS growth process, in order to control the diameter of the nanowires over the range from 45 nm to 200 nm. Intentional p-type and n-type doping was achieved through the addition of either trimethylboron, diborane or phosphine gas during nanowire growth. The electrical properties of undoped and intentionally doped silicon nanowires were characterized using field-assisted assembly to align and position the wires onto pre-patterned test bed structures. The depletion characteristics of back-gated nanowire structures were used to determine conductivity type and qualitatively compare dopant concentration. SiGe and SiGe/Si axial heterostructure nanowires were also prepared through the addition of germane gas during VLS growth. The Ge concentration in the wires was controllable over the range from 12 % to 25% by varying the inlet GeH4/SiH4 ratio.

  7. Personalidad Resistente en Carreras de Fondo: comparativa entre ultra fondo y diez kilómetros

    Ricardo de la Vega

    2011-01-01

    Full Text Available La Personalidad Resistente es una característica individual que permite hacer frente a los estímulos estresores de la vida y convertirlos en oportunidades de crecimiento (Kobasa, 1979; Maddi, 2006. Sus tres componentes: Compromiso, Control y Desafío pueden proteger a los deportistas contra las impredecibles situaciones de las carreras de fondo. El objetivo de este estudio fue comparar por primera vez los niveles de personalidad resistente de dos grupos de corredores de fondo, así como determinar si existe una relación entre los niveles de personalidad resistente y el rendimiento deportivo. 130 voluntarios (69 corredores de ultrafondo y 61 corredores participantes de una prueba de 10.06 kilómetros con un rango de edad de 20 a 56 años (M = 35.4, DT = 7.3, quienes completaron el día de la competición la Escala de Personalidad Resistente en Maratonianos (EPRM (Jaenes, Godoy y Román, 2008. El análisis de comparación de medias, reveló que no existieron diferencias significativas entre ambos grupos de corredores de fondo (Z = .280, p = .77, así mismo las mejores marcas en la prueba de ultra fondo fueron independientes de los niveles de personalidad resistente (r = -.072, p = .30, aquellos corredores que completaron el recorrido de ultrafondo no presentaron niveles mayores de personalidad resistente que los deportistas que abandonaron (p =. 78. Los resultados sugieren que un nivel elevado de personalidad resistente forma parte de las características psicológicas de los corredores de fondo. Por otra parte un nivel elevado de personalidad resistente no tuvo influencia sobre el rendimiento obtenido en una carrera de ultrafondo.

  8. LA EVOLUCIÓN DE LA RSC EN BRASIL ENTRE LAS EMPRES AS COTIZADAS EN BOVESPA

    Ana Gisbert

    2012-03-01

    Full Text Available El objetivo de este trabajo es analizar los avances en responsabilidad social en Brasil, haciendo énfasis en el tipo de información presentada y el nivel de las inversiones realizadas durante el período 2003-2007. El análisis empírico está basado en el contenido de los informes de RSC publicados por las empresas cotizadas en Bovespa, entre las que se encuentran las compañías que componen la cartera del Índice de Sostenibilidad Empresarial y Responsabilidad Social Corporativa de la bolsa de valores de Sao Paulo (Bovespa. La muestra analizada está compuesta por 48 compañías cotizadas. En el análisis empírico se ha analizado el contenido de los informes anuales de las empresas de la muestra entre los años 2003 a 2007. Todos los proyectos en RSC desarrollados por las compañías de la muestra han sido clasificados en 11 categorías, así como em tres grandes grupos de inversión: externa, interna y medioambiental. Los resultados ponen de manifiesto la necesidad de potenciar la estandarización del formato de presentación de los informes de responsabilidade social corporativa debido a la ausencia de uniformidad. Asimismo, se observa que las empresas invierten em proyectos que en la mayor parte de los casos están muy relacionados con la actividad principal que desarrollan. Respecto al crecimiento de la inversión, el mayor avance durante el periodo temporal analizado se encuentra en la inversión externa, si bien la inversión en proyectos internos ha aumentado de forma considerable. La inversión medioambiental es la que se ha mantenido, debido especialmente a una significativa reducción en el sector petrolífero.

  9. SiO2 as gas barrier and nano holes in SiO2 flakes

    Sublimation of SiO is used to protect PVD aluminium flakes from water corrosion and to generate highly porous SiO2 flakes with holes in the nanometer range. SiOx/Al/SiOx sandwiches were made as well as Ag loaded porous SiO2 as antimicrobial filler

  10. Risco nutricional entre gestantes adolescentes Riesgo nutricional entre gestantes adolescentes Nutritional risks among pregnant teenagers

    Glayriann Oliveira Belarmino

    2009-01-01

    Full Text Available OBJETIVOS: Identificar o acometimento de risco nutricional em gestantes adolescentes; averiguar hábitos alimentares; e verificar percepções destes quanto à importância de nutrição adequada na gravidez. MÉTODOS: Estudo de campo realizado no Centro de Desenvolvimento Familiar, em Fortaleza-CE, com 40 gestantes adolescentes. A avaliação nutricional foi efetuada com o auxílio do "Gráfico de acompanhamento nutricional da gestante" e os hábitos alimentares foram conferidos pela "Técnica de alimentação diária habitual". RESULTADOS: Vinte (50% adolescentes apresentaram peso adequado, 11(27,5% baixo peso e 9 (22,5% sobrepeso. Prevaleceram massas, carnes, gorduras, doces e baixo consumo de frutas e verduras; 33 (82,5% tinham a percepção de que a alimentação deve ser "diferente" na gravidez e 28 (70% afirmaram ter feito mudanças nos hábitos alimentares no pré-natal. CONCLUSÃO: O acometimento de risco nutricional entre adolescentes gestantes se revelou em situações de sobrepeso, baixo peso, dietas pouco diversificadas e desinformação.OBJETIVOS: Identificar el riesgo nutricional en gestantes adolescentes; averiguar hábitos alimenticios; y verificar percepciones de éstos en cuanto a la importancia de una nutrición adecuada en el embarazo. MÉTODO: Se trata de un estudio de campo realizado en el Centro de Desarrollo Familiar, en Fortaleza-CE, con 40 gestantes adolescentes. La evaluación nutricional se llevó a cabo con el auxilio del "Gráfico de acompañamiento nutricional de la gestante" y los hábitos alimenticios fueron conferidos por la "Técnica de alimentación diaria habitual". RESULTADOS: Veinte (50% adolescentes presentaron peso adecuado, 11(27,5% bajo peso y 9 (22,5% sobre peso. Prevalecieron pastas, carnes, grasas, dulces y bajo consumo de frutas y verduras; 33 (82,5% tenían la percepción de que la alimentación debe ser "diferente" durante el embarazo y 28 (70% afirmaron haber realizado cambios en los h

  11. Diferencias entre la composición sectorial y ocupacional de las principales ciudades chilenas

    Marcelo Lufín Varas

    2010-08-01

    Full Text Available La planifcación regional y urbana ha tendido a fjarse exclusivamente en la composición sectorial de las economías locales, asumiendo en forma implícita que la estructura de ocupaciones por actividad es similar a lo largo de un país. Si bien este supuesto parece ser cierto para el conjunto del tejido productivo, se encuentran diferencias signifcativas cuando se analizan ocupaciones específcas. Entre ellas destacan aquellas intensivas en conocimiento, las cuales tienden a estar sobrerrepresen-tadas en las principales ciudades. Se propone una metodología para el análisis de la relación existente entre la estructura de ocupaciones y la estructura sectorial y se aplica al estudio de las principales ciudades chilenas en 2002 a partir de la información del Censo de población, con el objetivo de estimar en qué medida estas estructuras divergen y si existen concentraciones relativas de ocupaciones, observándose que aquellas relacionadas con el conocimiento y la toma de decisiones empresariales tienen una presencia mayor que la esperada en el área metropolitana de Santiago.Regional and urban planning have tended to be exclusively focused on the industrial mix of local economies, implicitly assuming that the occupational mix of economic activities is similar throughout a country. Tis assumption seems to be right fom the perspective of the productive system as a whole, however signifcant diferences arise when analyzing certain occupations. Among them, knowledge-intensive occupations stand out and tend to be overrepresented in the main urban areas. A methodolog y is proposed to analyze the relationship between the occupational and industrial structures. Tis methodology is applied to the case of the principal Chilean cities in 2002 using data fom the population Census in order to estimate the extent to which these structures diverge and whether or not there are relative concentrations of occupations. Results show that the presence of managerial

  12. Room-temperature formation of Pt$_3$Si/Pt$_2$Si films on poly-Si substrates

    Dubkov, V P; Chizh, K V; Yuryev, V A

    2016-01-01

    We propose a way of formation of thin bilayer Pt$_3$Si/Pt$_2$Si films at room temperature on poly-Si substrates by Pt magnetron sputtering and wet etching, obtain such film, investigate its structure and phase composition and estimate the thickness of its layers. We verify by direct x-ray photoelectron-spectroscopic measurements our previous observation of the Pt$_2$Si layer formaton between Pt and poly-Si films as a result of Pt magnetron sputtering at room temperature. This layer likely appears due to high enough temperature of Pt ions in the magnetron plasma sufficient for chemical reaction of the silicide film formation on the Si surface. The Pt$_3$Si layer likely forms from the Pt--Pt$_3$Si layer (Pt$_{95}$Si$_5$), which arises under Pt film during the magnetron sputtering, as a result of Pt removal by wet etching.

  13. Si, Ge and SiGe wires for sensor application

    Resistance and magnetoresistance of Si, Ge and Si-Ge micro- and nanowires were studied in temperature range 4,2-300 K at magnetic fields up to 14 T. The wires diameters range from 200 nm to 20 μm. Ga-In gates were created to wires and ohmic I-U characteristics were observed in all temperature range. It was found high elastic strain for Ge nanowires (of about 0,7%) as well as high magnitude of magnetoresistance (of about 250% at 14 T), which was used to design multifunctional sensor of simultaneous measurements of strain and magnetic field intensity. (authors)

  14. Influence of SiC coating thickness on mechanical properties of SiC{sub f}/SiC composite

    Yu, Haijiao, E-mail: yunzeyu2000@163.com [College of Aerospace and Materials Engineering, National University of Defence Technology, Changsha 410073 (China); Advanced Composites Centre for Innovation and Science (ACCIS), Department of Aerospace Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Beijing Aeronautical Technology Research Centre, Beijing 100076 (China); Zhou, Xingui; Zhang, Wei [College of Aerospace and Materials Engineering, National University of Defence Technology, Changsha 410073 (China); Peng, Huaxin [Advanced Composites Centre for Innovation and Science (ACCIS), Department of Aerospace Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Zhang, Changrui [College of Aerospace and Materials Engineering, National University of Defence Technology, Changsha 410073 (China)

    2013-11-15

    Highlights: •CVD SiC coating improves the mechanical properties of 2D KD-I/SiC composite. •The thickness of SiC coating determines the mechanical properties of the composite. •The optimal thickness of CVD SiC coating is 0.34–1 μm. -- Abstract: Silicon carbide (SiC) coatings with varying thickness (ranging from 0.14 μm to 2.67 μm) were deposited onto the surfaces of Type KD-I SiC fibres with native carbonaceous surface using chemical vapour deposition (CVD) process. Then, two dimensional SiC fibre reinforced SiC matrix (2D SiC{sub f}/SiC) composites were fabricated using polymer infiltration and pyrolysis (PIP) process. Influences of the fibre coating thickness on mechanical properties of SiC fibre and SiC{sub f}/SiC composite were investigated using single-filament test and three-point bending test. The results indicated that flexural strength of the composites initially increased with the increasing CVD SiC coating thickness and reached a peak value of 363 MPa at the coating thickness of 0.34 μm. Further increase in the coating thickness led to a rapid decrease in the flexural strength of the composites. The bending modulus of composites showed a monotonic increase with increasing coating thickness.

  15. Comparación entre varias poblaciones estándar para el ajuste por edades

    Llorca Díaz Javier

    2000-01-01

    Full Text Available FUNDAMENTO: Analizar el efecto que tiene la elección de una población de referencia sobre diferentes indicadores derivados de las tasas de mortalidad ajustadas por edad. MÉTODOS: Las tasas de mortalidad por diferentes causas de muerte en España de 1971 a 1992 son ajustadas empleando cuatro poblaciones de referencia: poblaciones españolas de 1971 y 1992, población estándar europea y población estándar mundial. Los resultados obtenidos con las cuatro poblaciones se comparan empleando tres indicadores: diferencia entre las tasas de 1992 y 1971, razón entre las tasas de 1992 y 1971y cambio anual porcentual entre 1971 y 1992. RESULTADOS: En la mayor parte de las causas de muerte estudiadas incluyendo el total de causas, la cardiopatía isquémica y casi todos los tumores, la razón de tasas y el porcentaje de cambio anual son similares con independencia de cuál sea la población estándar empleada. En cambio, la diferencia de tasas es muy diferente en función de la población de referencia. En las enfermedades infecciosas y el cáncer de testículo se produce la situación contraria: la diferencia de tasas es robusta mientras que la razón de tasas varía con la población estándar. Finalmente, la mortalidad por neumonía, enfermedad de Parkinson y cáncer de encéfalo muestra cambios en los tres indicadores utilizados. CONCLUSIONES: Es necesario realizar un análisis de las tasas específicas por edad antes de proceder a su ajuste. Este análisis permite averiguar si el ajuste por edades es correcto y qué indicador (diferencia, razón o cambio porcentual será adecuado para realizar comparaciones.

  16. PARALELO ENTRE LA ACTIVIDAD Y LA SUSTANCIA ADICTIVA DESDE UN ENFOQUE SOCIAL Y SUS POSIBLES TRATAMIENTOS

    Alan Herzberg

    2007-01-01

    Full Text Available El tema de las adicciones ha sido abordado históric amente por la literatura desde múltiples puntos de vista, sin embargo en esta investigación bibliográfica nuestra intenci ón es dimensionar las teorías sobre el origen de la s adicciones, considerando la complementariedad teórica para la q ue se presta el tema, permitiendo un paralelo con l as terapias psicoanalíticas y la visión freudiana. Por otro lado están los tipos de adicción, entre lo s que se encuentran las directas, que se dirigen ha cia un objeto, y manifiestan un fuerte sentido de control (algunos e jemplos de adicciones de este tipo son el alcoholis mo, cocainomanías, heroinómanas, entre otras, y las in directas, caracterizadas por la búsqueda del placer liberado por las endorfinas en la acción generando un fuerte placer (algunos ejemplos de este tipo de adicciones son la s adicciones al sexo, al juego -ludopatía- y a los servicios de Int ernet entre otros A su vez nos encontramos con los tratamientos, y lo primero que sale a la luz es el tratamiento de alc ohólicos anónimos, donde es digna de analizar la dinámica y calidad de las redes sociales, por otro lado la est ructura de red social y su relación con las diferentes alteracione s y por ultimo el enfoque que se da a la integració n del nuevo abstemio. También se analizan los tratamientos desd e la mirada freudiana, junto con el tratamiento y e l control de adicciones. Pero el punto más importante de todo este análisis es la integración que hemos realizado desde la mira da social, ya que si bien es cierto que las diversas teorías apuntan en muchas formas a una raíz biológica, es el factor social el gatillador, ya que uno de los factores de riesgo que se reconoc e ampliamente en la literatura es la red social, as í como también dentro de los tipos de adicción se puede ver que la división que realizamos se basa exclusivamente en el locus de control, y por último se perciben en los tratamient os m

  17. Consecuencias de la caída de la fecundidad sobre los intercambios entre generaciones

    Meil Landwerlin, Gerardo

    2007-12-01

    Full Text Available This article analyzes the effects of the number of siblings and their sex composition as well as other indicators of individualization which are intertwined with the development of a beanpole type kin structure on interchanges among generations in Spain. The effects of this development varies according to the point of view adopted, the parents one or that of the adult children. Though this development increases the probability not to have daughters, there are no clear signs of a weakening of intergenerational ties derived from the development of a beanpole type kin structure. The biggest threat for the density of intergenerational relationships derives not as much from this development, but from the geographical dispersion of the generations caused by the lack of professional and employment opportunities for the younger generations.

    El objeto de este trabajo es analizar los efectos de la caída de la fecundidad sobre los intercambios materiales e inmateriales entre las generaciones (adultas y residentes en hogares independientes en España. El análisis atiende, entre otras variables, al número y a la composición por sexos de la generación más joven, analizando los intercambios entre las díadas hijo varón emancipado / padres e hija emancipada / padres. Los efectos de la caída de la fecundidad y otros cambios familiares asociados a la misma dependen del punto de vista que se adopte, esto es, si se analizan desde el punto de vista de los padres o de los hijos. A pesar de que la caída de la fecundidad aumenta la probabilidad de no tener hijas, no hay signos claros de un debilitamiento de las relaciones intergeneracionales derivadas de la caída de la fecundidad. Las mayores amenazas para la densidad de las relaciones intergeneracionales no derivan tanto de la caída de la fecundidad, como de la dispersión de las generaciones como consecuencia de la ausencia de expectativas laborales y profesionales para la generación más joven en

  18. Correlações entre caracteres quantitativos em milho pipoca Correlation among quantitative traits in popcorn maize

    Valéria Carpentieri-Pípolo

    2002-12-01

    Full Text Available Em um programa de melhoramento, o conhecimento da grandeza das associações entre caracteres de interesse, é de fundamental importância na obtenção de populações melhoradas. O presente trabalho teve como objetivo determinar as correlações genotípicas, fenotípicas e ambientais entre caracteres quantitativos em milho pipoca. Foram avaliados nove genótipos de milho pipoca dispostos no campo em delineamento em blocos casualizados com oito repetições. Os genótipos UEL ZP, UEL SI e UEL PAP revelaram maiores capacidades de expansão (27,50; 27,15 e 24,40 respectivamente e número de grãos por volume (244,75; 248,50 e 248,75 respectivamente. A capacidade de expansão revelou correlação fenotípica positiva com o tamanho da pipoca e com o número de grãos por volume, e correlação negativa com massa de grãos por planta. Os caracteres massa de grãos por planta e peso total da espiga revelaram correlações fenotípicas e genotípicas positivas entre si, o que possibilita a utilização de um ou outro na seleção, optando-se pelo que melhor convier aos propósitos do programa de melhoramento.Knowledge of the size of the association among traits of interest is of fundamental importance in a breeding program to allow genetic progress. The genotypic, phenotypic and environment correlation were studied among quantitative traits of popcorn maize. Nine popcorn maize genotypes were assessed. A randomized complete block design with eight replications was used. The UEL ZP, UEL SI and UEL PAP. genotypes which had greatest expansion capacity (27.50; 27.15 and 24.20, respectively, also had the greatest values for the number of grains per volume (244.75; 248.50 and 248.75, respectively. The expansion capacity correlated positively with the popcorn size and with number of grains per volume and negatively with plant yield. The traits plant yield, and total ear weight showed positive phenotypic and genotypic correlation that permits the choice of

  19. Presentación - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Primer vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  20. Introducción II - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Tercer vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  1. Ejecucion de la prueba - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Cuarto vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  2. Introducción I - Anova Factorial Entre Sujetos

    Serra Añó, Pilar; Ponce Darós, María José; López Bueno, Laura; González Moreno, Luis Millán; García Massó, Xavier; Anova Factorial Entre Sujetos

    2014-01-01

    Segundo vídeo de una serie de seis, donde se muestra la ejecución del análisis de varianza con el programa estadístico SPSS para comprobar diferencia de medias entre k grupos, en el área de las ciencias de la salud;

  3. Desarrollo del razonamiento deductivo: Diferencias entre condicionales fácticos y contrafácticos

    Juan A. García-Madruga

    2010-01-01

    Full Text Available El artículo analiza cómo los adultos y los niños realizan inferencias sobre lo que podría haber ocurrido pero no ocurrió (contrafácticos. Para ello, se utiliza una tarea de razonamiento deductivo con enunciados condicionales reales (o fácticos, del tipo "si corres, llegas a tiempo" y contrarios a la realidad (o contrafácticos, del tipo "si hubieras corrido, habrías llegado a tiempo", que se aplicó a participantes de distintas edades: niños de primero y segundo de primaria ( =7 años, niños de quinto y sexto de primaria ( =11 años, jóvenes de tercero y cuarto de secundaria ( =15 años, y adultos universitarios ( =23 años. Se realizaron dos estudios, el primero con adultos (60 participantes y el segundo con los distintos grupos de edad (7, 11 y 15 años, en total 156 participantes. Tanto niños como adultos mostraron diferentes patrones de inferencias cuando se presentaban condicionales fácticos y contrafácticos. La comparación de las frecuencias de inferencias entre adultos y niños mostró diferencias sólo para los condicionales fácticos, pero no para los condicionales contrafácticos. Los resultados se discuten considerando principalmente la propuesta de la teoría de los Modelos Mentales.

  4. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  5. Irradiation effects on thermal expansion of SiC/SiC composite materials

    Irradiation-induced dimensional change and thermal expansion of two kinds of composites, self-particle reinforced SiCp/SiC composites and a Hi-Nicalon SiC fiber reinforced SiCf/SiC composite, and monolithic α-SiC were measured after irradiation at 0.2 dpa with irradiation temperatures of 573, 673 and 843 K using the JMTR. From the measurement, swelling was observed for the SiCp/SiC composites and the monolithic α-SiC, on the contrary, the SiCf/SiC composites showed a shrinkage. The measured thermal expansion increased with increasing the specimen temperature below the irradiation temperature, and then rapidly decreased over the irradiation temperature. The so-called 'temperature monitor effect' of the silicon carbide was clearly observed for all specimens, the monolithic α-SiC and both composites

  6. High thermal conductivity SiC/SiC composites for fusion applications -- 2

    Kowbel, W.; Tsou, K.T.; Withers, J.C. [MER Corp., Tucson, AZ (United States); Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion Structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. An unirradiated SiC/SiC composite made with MER-developed CVR SiC fiber and a hybrid PIP/CVI SiC matrix exhibited room temperature transverse thermal conductivity of 45 W/mK. An unirradiated SiC/SiC composite made from C/C composite totally CVR-converted to a SiC/SiC composite exhibited transverse thermal conductivity values of 75 and 35 W/mK at 25 and 1000 C, respectively. Both types of SiC/SiC composites exhibited non-brittle failure in flexure testing.

  7. Bonding in MgSi and AlMgSi Compounds Relevant to AlMgSi Alloys

    Froseth, A. G.; Derlet, P. M.; Andersen, S.J.; Marioara, C. D.; Holmestad, R.

    2003-01-01

    The bonding and stability of MgSi and AlMgSi compounds relevant to AlMgSi alloys is investigated with the use of (L)APW+(lo) DFT calculations. We show that the $\\beta$ and $\\beta''$ phases found in the precipitation sequence are characterised by the presence of covalent bonds between Si-Si nearest neighbour pairs and covalent/ionic bonds between Mg-Si nearest neighbour pairs. We then investigate the stability of two recently discovered precipitate phases, U1 and U2, both containing Al in addi...

  8. Resonance Raman mapping as a tool to monitor and manipulate Si nanocrystals in Si-SiO2 nanocomposite

    Specially designed laser heating experiment along with Raman mapping on Si-SiO2 nanocomposites elucidates the contribution of core and surface/interface in the intermediate frequency range (511–514 cm−1) Si phonons. The contribution of core to surface/interface increases with the size of Si nanocrystal, which itself increases on laser irradiation. Further, it is found that resonance Raman is crucial to the observance of surface/interface phonons and wavelength dependent Raman mapping can be corroborated with band edges observed in absorption spectra. This understanding can be gainfully used to manipulate and characterize Si-SiO2 nanocomposite, simultaneously for photovoltaic device applications

  9. Mo-Si alloy development

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  10. Características individuales y actitudes discriminatorias hacia la mujer en México: ¿existen diferencias entre las regiones?

    Juan José Argaez

    2011-01-01

    Full Text Available Con base en los resultados de la Primera encuesta nacional sobre discriminación en México, en este artículo se examina la relación entre factores individuales y las actitudes discriminatorias hacia la mujer. El objetivo es evaluar empíricamente la influencia de estos factores en lo individual, y descubrir si existe alguna diferencia entre las regiones que lleve a la persistencia de actitudes discriminatorias. Los resultados concuerdan con las expectativas en cuanto a los factores individuales, y revelan que los habitantes del norte y centro de México mantienen actitudes discriminatorias más intensas que la población del sur del país.

  11. Un pequeño aumento en el espaciado entre letras favorece la lectura en niños disléxicos

    Victoria Panadero

    2012-09-01

    Full Text Available Varias investigaciones recientes han mostrado que un ligero aumento del espaciado entre las letras (respecto al espaciado estándar produce tiempos de lectura más rápidos en los niños con dislexia, así como mejoras en la comprensión de los textos. Si bien el aumento en el espaciado de las letras no “cura” la dislexia, sí permite una mejora en el proceso de lectura. Es importante remarcar que la posibilidad de modificar el espaciado entre letras se encuentra disponible en los programas de procesamiento de texto. Creemos que dicha opción debería estar disponible próximamente en los libros electrónicos.

  12. L’héritage de la principauté d’Orange. Enjeu entre le protecteur des Provinces-Unies et le roi de France

    Porte, Rémy

    2008-01-01

    Mal connue, l’histoire de la principauté d’Orange ne relève pas d’une histoire locale ou régionale traditionnelle. Paradoxalement, alors que sa superficie n’a jamais été considérable, la ville doit à sa position géographique et à un héritage complexe de jouer pendant cinq siècles un rôle important entre le royaume de France et le Saint- Empire germanique, puis entre catholiques et prostestants. Parallèlement aux différentes interventions prononcées aujourd’hui sur les relations franco-irlanda...

  13. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    Reinaldo Welti

    2002-01-01

    Full Text Available En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el generador que suministra energía a las mismas.

  14. Diferencias del clima laboral entre empleados contratados por outsourcing y empleados directos: evidencia empírica de la zona norte de Colombia.

    David Juliao Esparragoza

    2014-12-01

    Full Text Available Son pocos los estudios empíricos sobre clima laboral en Colombia que muestran las diferencias entre grupos de trabajadores que, teniendo las mismas funciones en la empresa, cuentan con diferentes tipos de contrato. Esta investigación, a partir de un estudio realizado con empleados de una importante empresa de bebidas ubicada en la costa norte de Colombia, trata de aportar a la resolución de esta carencia, verificando si existen diferencias significativas, en algunas variables del clima laboral, entre los grupos de trabajadores contratados directamente y aquellos vinculados por prestación de servicios. El trabajo es de tipo descriptivo y transversal, se apoya en el método hipotético inductivo y utiliza el instrumento imcoc (evaluando las diferencias inter-grupales en las seis variables que lo componen, a saber: objetivos, cooperación, liderazgo, toma de decisiones, relaciones interpersonales, motivación y control.

  15. Noms de famille, de baptême et surnoms recensés à Bayonne parmi les ressortissants de la "nation juive du bourg Saint-Esprit" au XVIIIème siècle

    Iglesias, Hector

    2002-01-01

    Etude anthroponymique concernant la communauté juive bayonnaise au XVIIIe siècle. Les archives bayonnaises conservent plusieurs documents du XVIIIe siècle concernant la nation juive du bourg Saint-Esprit . Parmi ces documents, on trouve, entre autres, l'enregistrement par le " Sieur rabbin de la nation Juive du bourg Saint-Esprit près Bayonne " de 219 mariages, de 1184 naissances et de 1140 décès entre 1751 et 1788. Nous avons retranscrit et analysé d'un point de vue onomastique ce corpus. Au...

  16. Estudio de Impacto Ambiental de la Remodelación de la Carretera AB-519 entre los términos municipales de Casas de Lázaro y Peñarrubia (Provincia de Albacete).

    GARCÍA ALCALÁ, ENRIQUE

    2016-01-01

    [ES] Se ha procedido a la redacción del Estudio de Impacto ambiental de la Remodelación de la Carretera AB-519 entre los términos municipales de Casas de Lázaro y Peñarrubia (Provincia de Albacete), que consiste en: Remodelar la carretera que conecta el municipio de Casas de Lázaro con el municipio de Peñarrubia. Se tiene que estudiar si la propuesta es viable medioambientalmente o si sería mejor no realizar ninguna actuación y dejar la infraestructura como está. Este proyecto incrementará la...

  17. Laser annealing of sputter-deposited -SiC and -SiCN films

    M A Fraga; M Massi; I C Oliveira; F D Origo; W Miyakawa

    2011-12-01

    This work describes the laser annealing of -SiC and -SiCN films deposited on (100) Si and quartz substrates by RF magnetron sputtering. Two samples of -SiCN thin films were produced under different N2/Ar flow ratios. Rutherford backscattering spectroscopy (RBS), Raman analysis and Fourier transform infrared spectrometry (FTIR) techniques were used to investigate the composition and bonding structure of as-deposited and laser annealed SiC and SiCN films.

  18. Analysis of Si/SiGe Heterostructure Solar Cell

    Ashish Kumar Singh

    2014-01-01

    Full Text Available Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005, is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of Si/Si1-xGex heterostructure solar cell. The research has investigated characteristics such as short circuit current density (Jsc, generation rate (G, absorption coefficient (α, and open circuit voltage (Voc with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases.

  19. Morphology Analysis of Si Island Arrays on Si(001

    González-González A

    2010-01-01

    Full Text Available Abstract The formation of nanometer-scale islands is an important issue for bottom-up-based schemes in novel electronic, optoelectronic and magnetoelectronic devices technology. In this work, we present a detailed atomic force microscopy analysis of Si island arrays grown by molecular beam epitaxy. Recent reports have shown that self-assembled distributions of fourfold pyramid-like islands develop in 5-nm thick Si layers grown at substrate temperatures of 650 and 750°C on HF-prepared Si(001 substrates. Looking for wielding control and understanding the phenomena involved in this surface nanostructuring, we develop and apply a formalism that allows for processing large area AFM topographic images in a shot, obtaining surface orientation maps with specific information on facets population. The procedure reveals some noticeable features of these Si island arrays, e.g. a clear anisotropy of the in-plane local slope distributions. Total island volume analysis also indicates mass transport from the substrate surface to the 3D islands, a process presumably related to the presence of trenches around some of the pyramids. Results are discussed within the framework of similar island arrays in homoepitaxial and heteroepitaxial semiconductor systems.

  20. Vitrail, verre et archéologie entre le ve et le xiie siècle

    Christian Sapin

    2010-10-01

    Full Text Available Depuis longtemps, les fouilles archéologiques ont fait apparaître des fragments de verre en très grand nombre. L’intérêt des archéologues, orienté dans un premier temps vers les verres creux, se tourne de plus en plus vers les fragments de verre plat. Ceci conduit à poser de nouvelles questions sur les diverses utilisations du verre dans l’architecture, tant civile que religieuse, en particulier pour ce qui touche à la fermeture des baies ou au décor intérieur. Cette publication fait un point...

  1. Entre Velhos e Outros nem tão Idosos Assim: Cuidado de Si em Tempos de Biopoder

    Lazaro Batista da Fonseca

    2011-12-01

    Full Text Available Nowadays old age has become a target for an endless number of practices supported by the medical discourse of“life quality” and “best age”. In contradiction with the ascetic ways from the Past, this bioascesis establishes newvalues for the elderly based on hygienic rules, schemes of time occupation and ideal models of subject based onphysical performance, culminating on an unbridled pursuit for better physical shape, more longevity, prolongationof youth, etc. The purpose of this text is to present evidence of how this discourse was established and how it hasregulated practices geared towards the elderly. It also intends to present the ways to resist the culture of fitnesswithin groups geared towards bioascetic practices.

  2. Diffusion mobilities in the fccA1 Cu–Si, Al–Si and Al–Cu–Si alloys

    Highlights: ► The atomic mobilities of fcc Cu–Si, Al–Si and Al–Cu–Si alloys have been assessed. ► The calculated results agree well with various experimental diffusivities. ► The temperature and concentration dependence are taken into consideration. ► The mobility parameters obtained can be used to predict many diffusion phenomena. - Abstract: Based on the available thermodynamic parameters and experimental data of self-diffusivity, impurity diffusivity, intrinsic diffusivity, tracer diffusivity and interdiffusivity in the Cu–Si, Al–Si and Al–Cu–Si alloys, the atomic mobilities of Cu, Al and Si in face-centered cubic (fccA1) Cu–Si, Al–Si and Al–Cu–Si alloys have been critically assessed as a function of temperature and composition using the CALPHAD-type and DICTRA software package. Comparisons between the calculated and measured coefficients reveal that most of the diffusivities can be reproduced satisfactorily. The obtained mobility parameters can be used to study diffusion-related characteristics for fccA1 Cu–Si, Al–Si and Al–Cu–Si alloys.

  3. Oxidation behavior of SiC/SiC composites for helium cooled solid breeder blanket

    In order to evaluate the oxidation behavior and mechanism of SiC/SiC composites with conventional pyrolitic graphite interface (PyC-SiC/SiC) and advanced multilayer interface (ML-SiC/SiC) in a HCSB blanket environment, a thermal gravimetric analysis (TGA) in He + O2 environment at 1000 deg. C and 1200 deg. C was performed. The PyC-SiC/SiC at 1200 deg. C and the ML-SiC/SiC at 1000 deg. C and 1200 deg. C showed relatively smaller weight change during oxidation because SiO2 formed on the SiC-matrix and SiC-fiber sealed the specimen surface before the PyC interface recession by gasification of graphite due to relatively high SiO2 formation rate. While the PyC-SiC/SiC at 1000 deg. C showed significant weight loss because the specimen surface was not sealed by SiO2 and significant PyC interface recession occurred due to relatively slow SiO2 formation

  4. Interface engineering of photoelectrochemically prepared Si surfaces

    Lewerenz, H.J.; Murrell, C.; Kanis, M.; Jungblut, H. [Department of Interfaces, Bereich Solarenergie, Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany); Aggour, M. [University of Tofail, Kenitra (Morocco); Hoffmann, P.; Schmeisser, D. [Fakultaet 1, Brandenburgisch-Technische Universitaet, Cottbus (Germany)

    2002-05-01

    The oxide of Si(111) formed by electropolishing in dilute ammonium fluoride solution is analysed by photoelectron spectroscopy using synchrotron radiation. The oxidic layer is about 3.1 nm thick and contains Si-F{sub x} species as well as oxyfluorides. The oxyfluorides are found preferentially at the electropolishing layer surface. SiOH species are concentrated at the oxidic film/substrate interface. The full width half maximum of the Si 2p line indicates that the Si/electropolishing oxide interface is smoother than the Si/natural oxide interface.

  5. Microwave joining of SiC

    Silberglitt, R.; Ahmad, I.; Tian, Y.L. [FM Technologies, Inc., Fairfax, VA (United States)] [and others

    1997-04-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on identification of the most effective joining methods for scale-up to large tube assemblies, including joining using SiC produced in situ from chemical precursors. During FY 1996, a new microwave applicator was designed, fabricated and tested that provides the capability for vacuum baking of the specimens and insulation and for processing under inert environment. This applicator was used to join continuous fiber-reinforced (CFCC) SiC/SiC composites using a polymer precursor to form a SiC interlayer in situ.

  6. Straight β-SiC nanorods synthesized by using C-Si-SiO2

    Lai, H. L.; Wong, N. B.; Zhou, X. T.; Peng, H. Y.; Au, Frederick C. K.; Wang, N.; Bello, I.; Lee, C. S.; Lee, S. T.; Duan, X. F.

    2000-01-01

    Straight beta-silicon carbide nanorods have been grown on silicon wafers using hot filament chemical vapor deposition with iron particles as catalyst. A plate made of a C-Si-SiO2 powder mixture was used as carbon and silicon sources. Hydrogen, which was the only gas fed into the deposition system, acts both as a reactant and as a mass transporting medium. The diameter of the β-SiC nanorod ranged from 20 to 70 nm, while its length was approximately 1 μm. A growth mechanism of beta-silicon carbide nanorods was proposed. The field emission properties of the beta-silicon carbide nanorods grown on the silicon substrate are also reported.

  7. Comportamento de violência e fatores associados entre estudantes de Barra do Garças, MT

    Marta de Lima Castro

    2011-12-01

    Full Text Available OBJETIVO: Estimar a prevalência de violência entre adolescentes e jovens adultos e identificar fatores associados. MÉTODOS: Estudo transversal com amostragem aleatória sistemática de 699 estudantes do ensino fundamental e médio da rede pública urbana de Barra do Garças, MT, em 2008. Questionário autopreenchível foi aplicado em sala de aula sem a presença do professor. O desfecho "comportamento violento" foi definido como (1 uso de arma de fogo ou branca, e/ou (2 agressões contra si e ou terceiros, e/ou (3 tentativa de suicídio. As variáveis independentes analisadas foram idade, gênero, condição socioeconômica, uso de álcool, uso de drogas psicoativas, atividade sexual e relacionamento com os pais. Foram realizadas análises univariadas e regressão múltipla ajustada para efeito de agregado. RESULTADOS: A prevalência de violência foi de 18,6%, variando segundo a idade: de 10,1% no grupo de dez e 11 anos; 20,2% dos 12 aos 19 anos; e 4,5% dos 20 e 21 anos. Os fatores associados ao comportamento de violência foram uso de álcool (RP = 2,51, IC95% 1,22;5,15, uso de drogas psicoativas (RP = 2,10, IC95%1,61;2,75, gênero masculino (RP = 1,63, IC95% 1,13;2,35 e relações insatisfatórias entre os pais (RP = 1,64, IC95% 1,25;2,15. CONCLUSÕES: Os resultados indicam alta prevalência de violência entre os adolescentes na faixa etária de 12 a 19 anos, sobretudo entre os usuários de álcool e drogas, do sexo masculino, de família cujos pais não possuem relações satisfatórias. Embora sem significância estatística no modelo final de regressão, a defasagem escolar e nível socioeconômico devem ser considerados em ações educativas de prevenção ao comportamento de violência entre estudantes.

  8. Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures

    Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance–voltage (C–V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3–4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements. (paper)

  9. Relación entre concentraciones séricas de vitamina 25(oh)d y niveles de estrés oxidativo en una población de diabéticos tipo 2 (2011) / Relationship between serics concentracion of vitamin 25(oh) d and oxidative stress levels in a population of diabetes mellitus type 2 (2011).

    Rocha , Paula Maritza

    2012-01-01

    Objetivo: Determinar si existe una relación entre las concentraciones séricas de vitamina 25 (OH)D y estado de estrés oxidativo en pacientes con DM2 controlada. Muestra: Se reclutaron 19 pacientes, rango de edad 55 +/-10 años, HG A1c

  10. Relación entre variables antropométricas y dismorfia muscular en gimnastas de la provincia de Alicante

    Martínez-Segura, Asier; Rizo Baeza, María Mercedes; Sánchez Ferrer, Marina; Reig García-Galbis, Manuel Felipe; Cortés Castell, Ernesto

    2014-01-01

    Objetivo: Se muestra un estudio novedoso en el que se analiza si las medidas antropométricas pueden ser utilizadas para clasificar la dismorfia muscular (DM), en gimnastas que asisten a sala de musculación. Metodología: Se analizaron gimnastas de varias salas de musculación de Alicante (zona urbana del sureste español), donde se recogieron las medidas de 141 varones de edad comprendida entre 18-45 años, que persiguen el aumento de su masa muscular. Se tuvieron en cuenta el cálculo del IMC (kg...

  11. Relación entre el trabajo de fuerza en seco y el trabajo de fuerza en el agua en jugadores de waterpolo

    Moisès Vila Blanch; Joan Solé Fortó; Josep Maria Padullés Riu

    2014-01-01

    El propósito del presente estudio fue determinar si se establecen correlaciones entre la potencia muscular de las extremidades superiores e inferiores, mediante los ejercicios pectoral contractor o “pec-deck” y prensa de piernas, con la velocidad de lanzamiento con dos técnicas distintas (T1: lanzamiento con apoyo inicial del balón en el agua. T2: lanzamiento con doble finta), la altura y altura mantenida de salto y las características antropométricas en 9 jugadores de la selección catalana d...

  12. TRANSFERENCIA DE FUNCIONES SINTÁCTICAS ARTIFICIALES ENTRE ESTÍMULOS RELACIONADOS POR EQUIVALENCIA: UN ESTUDIO DE POTENCIALES CEREBRALES RELACIONADOS CON EVENTOS

    ANGEL TABULLO; ALBERTO YORIO; SILVANO ZANUTTO; ALEJANDRO WAINSELBOIM

    2015-01-01

    La formación de clases de equivalencia entreestímulos ha sido propuesta en el campo del Aná-lisis Experimental del Comportamiento como unprerrequisito conductual para el lenguaje. Adi-cionalmente, existe evidencia de que la transfe-rencia de función entre estímulos equivalentespo dría explicar la adquisición de estructuras sin-tácticas simples. No obstante, la simplicidad delas funciones sintácticas estudiadas no capturó lacomplejidad combinatoria de la gramática natu-ral. Si la transferencia...

  13. Relación entre la creatividad y las funciones ejecutivas en alumnos de Educación Infantil. Propuesta de intervención.

    Díaz-Rojas, Irene

    2014-01-01

    El objetivo de la presente investigación es proponer un programa de intervención neuropsicológico para desarrollar la creatividad en un grupo de 30 alumnos de Educación Infantil. Además se ha tratado de identificar si existe correlación entre el nivel de función ejecutiva (asociada a la corteza prefrontal) y el nivel de creatividad en la muestra estudiada. Para medir ambos constructos en la muestra analizada (con edades de 3 a 6 años) se empleó un cuestionario de creatividad y ...

  14. La abierta competencia entre el reconocimiento jurídico y la valoración social. El caso de la violencia de pareja

    María Carolina Agoff

    2009-01-01

    Este artículo analiza el proceso de apropiación subjetiva de derechos de parte de las mujeres en el marco de las nuevas legislaciones que promueven la igualdad de género y el derecho a una vida libre de violencia en México. Si bien se observa una incipiente transformación de una cultura de las virtudes femeninas tradicionales en una cultura de derechos emancipatoria, existen aún muchos obstáculos para una tal apropiación. Se trata del conflicto entre normatividades, en particular, las normas ...

  15. Grado de Relación e Influencia entre el Desarrollo de Competencias Comunicativas de Alumnos de Tercero de Primaria y la Estrategia de Aprendizaje Basada en Proyectos

    Hernández-Pérez, Dulce T.

    2012-01-01

    La investigación que a continuación se presenta se configura dentro del ámbito de estrategias de aprendizaje innovadoras, es descriptiva y está dirigida fundamentalmente a comprobar si existe grado de relación e influencia entre el desarrollo de competencias comunicativas en alumnos de tercer grado de educación primaria y la estrategia de aprendizaje basada en proyectos. El universo que ha abarcado la investigación es el circunscrito a alumnos y maestros de tercer grado de las escuelas...

  16. Relación entre maltrato fetal, violencia y sintomatología depresiva durante el embarazo de mujeres adolescentes y adultas: Un estudio piloto

    Galicia Moyeda, Iris Xóchitl; Universidad Nacional Autónoma de México; Martínez Sánchez, Brenda; Universidad Nacional Autónoma de México; Ordoñez Cervantes, Dulce María; Universidad Nacional Autónoma de México; Rosales Vega, Heizel Alida; Universidad Nacional Autónoma de México

    2013-01-01

    La adolescencia es una etapa vulnerable para algunas mujeres, pues se ha encontrado que sufren más depresión y violencia que las mujeres adultas, en especial si se encuentran encintas. Estas circunstancias pueden influir para que haya violencia hacia el producto. De ahí que el objetivo de este trabajo fue identificar la relación existente entre la violencia, la depresión y el maltrato fetal en 48 mujeres embarazadas adolescentes y adultas. Participaron mujeres que asistían a control prenatal ...

  17. Ciencia entre España e Hispanoamérica. Ecos del siglo XX (C. Acosta rizo, N.Cuvi, X.Roque)

    Sancho, Rosa

    2003-01-01

    Aunque el título resulta algo impreciso, se trata de un libro que pretende mostrar la historia del flujo o intercambio científico y técnico que ha tenido lugar entre España e Hispanoamérica desde la conquista y colonización hasta nuestros días, si bien cubriendo de forma muy desigual los distintos periodos de tiempo y las distintas disciplinas. Desde el punto de vista formal el libro está estructurado como una revisión bibliográfica. El texto está plagado de frases y párrafos e...

  18. A colisão entre a tutela dos direitos individuais e os valores fundamentais da sociedade na jurisprudência penal brasileira

    Lopes, Erivan José da Silva

    2015-01-01

    No universo em franco desenvolvimento da dogmática dos direitos fundamentais, uma das evoluções mais produtivas diz respeito a sua dimensão objetiva, que atribui ao Estado um dever de proteção, não apenas sob o ponto de vista dos indivíduos, mas igualmente sob o ponto de vista da sociedade, já que se cuida de valores e fins que esta deve respeitar e concretizar. Por também possuírem natureza de normas principiológicas, as normas de direitos fundamentais, quando entram em colisão entre si, exi...

  19. Cerrando la brecha entre nativos e inmigrantes digitales a través de las competencias informáticas e informacionales

    Ariel Sánchez Espinoza; Diana Castro Ricalde

    2013-01-01

    En este texto hacemos una reflexión acerca de las diferencias entre los llamados “nativos” e “inmigrantes digitales”, y aportamos datos que permiten identificar si un grupo tiene mayores ventajas sobre otro en relación con la enseñanza y el aprendizaje en esta era digital. Proponemos la adquisición y el desarrollo de competencias informáticas e informacionales en ambos grupos como estrategia para reducir la brecha digital “blanda” que priva en el sistema educativo e invitamos a resolver las i...

  20. Hachas grabadas, placas grabadas y comunicación visual suprarregional entre grupos cazadores-recolectores de finales del Holoceno tardío

    Acevedo, Agustín

    2015-01-01

    Este trabajo analiza los diseños grabados en las superficies de hachas y placas líticas procedentes de Patagonia, Pampa y –en menor medida– Sierras Centrales, Cuyo, Mesopotamia y Noroeste Argentino. Se propone discutir si ambos tipos de artefactos decorados formaron parte de un sistema de comunicación visual entre grupos cazadores-recolectores que operó a escala intra e interregional hacia finales del Holoceno tardío, partiendo desde un marco teórico que combina elementos de enfoques ecológic...

  1. Análisis de los huracanes originados entre 1990 y 2011 en el Atlántico Norte y mar Caribe

    Bou Parés, Elisenda

    2012-01-01

    Los objetivos de este trabajo son analizar los Huracanes más significativos habidos entre 1990 y 2011; aquellos digamos “curiosos” por la zona geográfica donde se han originado y los que han incluso llegado a las costas gallegas y europeas; averiguar por qué unos años son más intensos que otros; si tiene influencia el calentamiento global u otros factores (Niño/Niña…), en el aumento de la frecuencia e intensidad de los huracanes; qué nuevas tecnologías hay para su detección; hasta qué punto i...

  2. Pasiones políticas e imperialismo : la polémica entre Ginés de Sepúlveda y Bartolomé de las Casas

    Chaparro, Sandra

    2001-01-01

    Durante siglos el «amor» se ha venido considerando una virtud política, sostenedora de la vida comunitaria y fuente de la solidaridad social. Como tal, se trata de una pasión que se encuentra en la base de los sistemas simbólicos del pensamiento político occidental, si bien hoy, pasiones y política parecen dos conceptos alejados entre sí No obstante, en un mundo en vías de globalización resurgen con fuerza términos como solidaridad o cooperación, conceptos ...

  3. La creciente importancia de la Cooperación Sur-Sur en las relaciones económicas entre Asia y ALC

    Jae Sung Kwak

    2013-01-01

    Suele argumentarse que el actual esquema de cooperación 'complementaria' en el ámbito transpacífico entre países de Asia Oriental y de América Latina y el Caribe (ALC) no es sustentable en términos de comercio e inversión. Básicamente, las economías de ALC exportan materias primas de bajo valor agregado a la región del Asia Pacífico, a cambio de bienes manufacturados de alto valor agregado. Si bien este esquema presenta aspectos positivos y negativos para ambas regiones, funciona en base a un...

  4. Flujo de potencia entre estructuras complejas sometidas a excitaciones de alta frecuencia y aplicaciones a la detección de daño estructural

    Torrealba Palacios, Manuel

    2009-01-01

    El tema central de investigación en esta Tesis es el estudio del comportamientodinámico de una estructura mediante modelos que describen la distribución deenergía entre los componentes de la misma y la aplicación de estos modelos parala detección de daños incipientes.Los ensayos dinámicos son un modo de extraer información sobre las propiedadesde una estructura. Si tenemos un modelo de la estructura se podría ajustar éstepara que, con determinado grado de precisión, tenga la misma respuesta q...

  5. Diferencias del clima laboral entre empleados contratados por outsourcing y empleados directos: evidencia empírica de la zona norte de Colombia.

    David Juliao Esparragoza; Ciro Sánchez Bejarano; Domingo Martínez Díaz

    2014-01-01

    Son pocos los estudios empíricos sobre clima laboral en Colombia que muestran las diferencias entre grupos de trabajadores que, teniendo las mismas funciones en la empresa, cuentan con diferentes tipos de contrato. Esta investigación, a partir de un estudio realizado con empleados de una importante empresa de bebidas ubicada en la costa norte de Colombia, trata de aportar a la resolución de esta carencia, verificando si existen diferencias significativas, en algunas variables del clima labora...

  6. CULTURA NACIONAL EN MÉXICO Y COMPORTAMIENTO VERDE. Una comparación entre el modelo de individualismo de Hofstede y de relaciones personales de Trompe

    Eva Conraud Koellner; Luis Arturo Rivas Tovar

    2010-01-01

    Este artículo analiza la cultura nacional en México mediante los modelos de Hofstede y de relaciones personales de Trompenaars y compara los valores culturales entre los países de mayor comportamiento verde en el mundo. Si bien, los resultados son coincidentes en cuanto a que la cultura mexicana es claramente tradicional y colectivista, y que presenta los niveles más bajos de comportamiento verde, en los últimos años se percibe una evolución que hace relevante emprender campañas de marketing ...

  7. CIUDADANÍA FISCAL Y NUEVAS FORMAS DE RELACIÓN ENTRE CONTRIBUYENTES Y ADMINISTRACIÓN TRIBUTARIA

    Alejandro M. Estévez

    2009-01-01

    Full Text Available Usualmente, el cumplimiento fiscal ha sido explicado por el riesgo de la coerción. Este artículo analiza la nueva orientación de las administraciones tributarias, a fin de comprender cómo este hecho puede alentar la cultura tributaria de las sociedades, a través de la autorregulación y el cumplimiento voluntario. Aunque la mejora de la relación entre administración tributaria y el contribuyente no asegura en su totalidad, ni es la única manera para lograr el cumplimiento tributario, si constituye un factor determinante para aumentar la voluntad de cooperación de cada contribuyente y su intención en colaborar con su esfuerzo individual al sostenimiento de una sociedad general.

  8. À l’origine du gothique comtois : entre esthétique cistercienne et historicisme

    Jeudy, Fabienne

    2015-01-01

    L’art gothique apparu en Île-de-France dès 1135 atteignit le nord du comté de Bourgogne – actuelle Franche-Comté – vers 1160. En ce territoire à la charnière entre le royaume de France et le Saint Empire dont il relevait depuis le début du XIe siècle, l’esprit était alors à l’austérité. La réforme grégorienne avait eu un tel retentissement que la vie artistique elle-même en fut impactée. Sur le plan architectural, les maîtres d’œuvre, délaissant les recherches menées jusqu’alors en termes de ...

  9. Phonon heat transport in superlattices: Case of Si/SiGe and SiGe/SiGe superlattices

    Hijazi, M.; Kazan, M.

    2016-06-01

    We present a predictive Boltzmann model for the cross-plane thermal conductivity in superlattices. The developed model considers particle-like phonons exhibiting wave characteristics at the interfaces and makes the assumption that the phonon heat transport in a superlattice has a mixed character. Exact Boltzmann equation comprising spatial dependence of phonon distribution function is solved to yield a general expression for the lattice thermal conductivity. The intrinsic phonon scattering rates are calculated from Fermi's golden rule, and the model vibrational parameters are derived as functions of temperature and crystallographic directions by using elasticity theory-based lattice dynamics approach. The developed theory is then adapted to calculate the cross-plane thermal conductivity of superlattices. It is assumed that the phonons of wavelengths comparable or smaller than the superlattice period or the root mean square irregularity at the superlattice interfaces may be subject to a resistive scattering mechanism at the interfaces, whereas the phonons of wavelengths much greater than the superlattice period undergo ballistic transmission through the interfaces and obey dispersion relations determined by the Brillouin zone folding effects of the superlattice. The accuracy of the concept of mixed phonon transport regime in superlattices is demonstrated clearly with reference to experimental measurements regarding the effects of period thickness and temperature on the cross-plane thermal conductivity of Si/Si0.7Ge0.3 and Si0.84Ge0.16/Si0.76Ge0.3 superlattices.

  10. Estudio sobre las relaciones filogenéticas entre diversos aislamientos del hongo Paracoccidioides brasiliensis

    Juan McEwen

    2003-01-01

    Full Text Available Aunque es poco lo que se conoce acerca de la biología evolutiva
    del hongo P. brasiliensis, varios estudios moleculares han demostrado que existen variaciones en secuencias de ADN entre sus aislamientos, las que se correlacionan con el origen geográfico de las mismas y con diferencias en su virulencia para modelos murinos (1,2. Se desconoce si estas variaciones son el resultado final de un proceso de especiación alopátrica que daría origen a especies aisladas genéticamente provistas de características fenotípicas (patogenicidad, inmunogenicidad y genotípicas diferentes, las que podrían ser usadas como una alternativa para mejorar e innovar los métodos actuales de diagnóstico. Por lo tanto, proponemos como objetivo general estudiar un aspecto fundamental de la biología evolutiva del hongo patógeno humano P. brasiliensis como es la especiación.

  11. Las relaciones especiales de sujeción entre el Estado y sus funcionarios

    Luis Eduardo Ardila Quiroz

    2012-01-01

    Full Text Available Este escrito hace alusión a relaciones que existe entre el Estado y sus funcionarios, desde la obediencia en Grecia, hasta la connotación que adquiere el servidor público en el Estado Social de Derecho; y a su vez, las de estos para con sus asociados, pues bien sabido es que quienes sostienen al Estado y a todo el personal necesario para la exteriorización de aquel, son quienes pagan impuestos y contribuyen para que el presupuesto de gastos en bienes y servicios lleguen a buen puerto.Así como existen obligaciones por parte del Estado, también existen deberes que cumplir por parte de quienes lo habitan, por eso es de obligatorio cumplimiento, so pena de incurrir en un delito, el pago de contribuciones a favor del Estado, pero para que las erogaciones por parte del Estado hacia su población tengan la teleología o el fin propuesto, es necesario de una buena administración, si ello no acontece, se pierde la filosofía de las buenas maneras.

  12. Palladium transport in SiC

    Olivier, E.J., E-mail: jolivier@nmmu.ac.za [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. Black-Right-Pointing-Pointer The high temperature mobility of palladium silicides within polycrystalline SiC was studied. Black-Right-Pointing-Pointer Corrosion of SiC by Pd was seen in all cases. Black-Right-Pointing-Pointer The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. Black-Right-Pointing-Pointer The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd{sub 2}Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  13. Palladium transport in SiC

    Highlights: ► We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. ► The high temperature mobility of palladium silicides within polycrystalline SiC was studied. ► Corrosion of SiC by Pd was seen in all cases. ► The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. ► The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd2Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  14. Obtenção de substratos cerâmicos no sistema Si-Al-O-N-C empregando polissiloxanos e carga de Si e Al2O3 Ceramic tapes of Si-Al-O-N-C compounds using mixtures of polyssiloxane and Si-Al2O3 fillers

    R. M. Rocha

    2005-03-01

    Full Text Available A técnica de processamento de colagem por fita (tape casting tem sido amplamente utilizada na obtenção de cerâmicas para diferentes aplicações: substratos cerâmicos e estruturas planares em multicamadas para circuitos integrados e capacitores; eletrólitos sólidos para células a combustível e sensores; cerâmicas piezoelétricas para atuadores e transdutores; membranas de separação para micro-filtragem; compósitos estruturais e trocadores de calor. Neste trabalho, a técnica convencional de colagem por fita foi adaptada com a utilização do processo de pirólise controlada de misturas de polímeros e carga, empregando-se polissiloxanos e cargas de silício e alumina nas suspensões. Foram preparadas suspensões com 60% vol. de fase polimérica (polissiloxanos e metil-trietoxi-silano e 40% vol. de carga (Si e Al2O3, com diferentes concentrações dos polímeros e das cargas. As amostras na forma de substratos foram pirolisadas em atmosfera de nitrogênio a 1400 °C/2 h e 1500 °C/2 h, sendo convertidas em materiais cerâmicos no sistema Si-Al-O-N-C. O processo de pirólise foi caracterizado até a temperatura de 1000 ºC por análise termogravimétrica. As cerâmicas foram caracterizadas quanto às fases formadas, microestrutura, massa específica aparente e condutividade térmica. Os substratos cerâmicos apresentaram porosidade relativamente alta (entre 12 e 22% e baixa condutividade térmica (entre 3 e 8 W/m.K, sendo constituídos por fases cristalinas de beta-SiC, Si2ON2, O'-SiAlON, Al2O3, mulita e fase amorfa de SiOC; o Si foi observado nas amostras pirolisadas a 1400 ºC.The tape casting technique has been widely used to prepare ceramic tapes for different applications: ceramic substrates and multilayer planar structures for integrated circuits and capacitors, solid electrolytes for fuel cells and sensors, piezoelectric ceramics for actuators and transducers, membrane systems for micro-filtration, structural composites and

  15. Atomically controlled hetero-epitaxy of Fe3Si/SiGe for spintronics application

    Molecular beam epitaxy of the ferromagnetic silicide Fe3Si on Ge and Si substrates was investigated in a wide temperature range (60-400 deg. C). Epitaxial growth of Fe3Si layers was achieved on Ge (110), Ge (111), and Si (111) substrates. Especially, very low value (2.2%) of the minimum scattering yield in RBS measurements was obtained from Fe3Si layers, which were grown on Ge (111) at low temperature (60-130 deg. C) under the stoichiometric condition (Fe:Si = 3:1). Transmission electron microscopy measurements confirmed the formation of DO3-type Fe3Si and atomically flat interface between Fe3Si and Ge (111). In addition, thermal stability of Fe3Si was guaranteed up to 300 deg. C. Such high quality Fe3Si on Ge (111) substrates can be employed to realize Ge channel spin transistors, which can be integrated with Si large-scale integrated circuits

  16. Raman scattering studies of chemical-vapor-deposited cubic SiC films of (100)Si

    Feng, Z. C.; Mascarenhas, A. J.; Choyke, W. J.; Powell, J. A.

    1988-01-01

    Raman scattering studies for a series of CVD-grown cubic SiC single-crystal films with film thickness from 600 A to 17 microns are discussed. The results suggest that the crystalline orientations of the Si substrate and the 3C-SiC film are the same. It is found that the Si 522/cm phonon from a Si wafer is enhanced in intensity by a factor of 2-3 due to a CVD overlayer of cubic SiC, and that the 3C-SiC longitudinal optical phonon at the Gamma point from SiC/Si samples is enhanced by a factor of two or three following the removal of the Si substrate. The variation of the Raman spectrum with incident power is investigated, and a method for determining the Raman cross section for 3 C-SiC is proposed.

  17. Study and Simulation of the Heterojunction Thin Film Solar Cell a-Si(n)/a-Si(i)/c-Si(p)/a-Si(i)/a-Si(p)

    Toufik, Zarede; Hamza, Lidjici; Mohamed, Fathi; Achour, Mahrane

    2016-05-01

    In this article, we present a study based on numerical simulation of the electrical characteristics of a thin-film heterojunction solar cell (a-Si(n)/a-Si(i)/c-Si(p)/a-Si(i)/a-Si(p)), using the automat for simulation of hetero-structures (AFORS-Het) software. This cell is composed of four main layers of silicon (Si): (i) 5 nm amorphous silicon doped n, (ii) 100 μm crystalline silicon (substrate) doped p, (iii) 5 nm amorphous silicon doped p, and (iv) 3 nm amorphous silicon intrinsic. This cell has a front and rear metal contact of aluminum and zinc oxide (ZnO) front layer transparent conductive oxide of 80 nm thickness. The simulations were performed at conditions of "One Sun" irradiation with air mass 1.5 (AM1.5), and under absolute temperature T = 300 K. The simulation results have shown a high electrical conversion efficiency of about 30.29% and high values of open circuit voltage V oc = 779 mV. This study has also shown that the studied cell has good quality light absorption on a very broad spectrum.

  18. The HFIR 14J irradiation SiC/SiC composite and SiC fiber collaboration

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Kohyama, Akira; Katoh, Yutai [Kyoto Univ., Uji, Kyoto (Japan); Hasegawa, Akira [Tohoku Univ., Aramaki, Sendai (Japan); Snead, L. [Oak Ridge National Lab., TN (United States); Scholz, R.

    1998-09-01

    A short introduction with references establishes the current status of research and development of SiC{sub f}/SiC composites for fusion energy systems with respect to several key issues. The SiC fiber and composite specimen types selected for the JUPITER 14J irradiation experiment are presented together with the rationale for their selection.

  19. The HFIR 14J irradiation SiC/SiC composite and SiC fiber collaboration

    A short introduction with references establishes the current status of research and development of SiCf/SiC composites for fusion energy systems with respect to several key issues. The SiC fiber and composite specimen types selected for the JUPITER 14J irradiation experiment are presented together with the rationale for their selection

  20. Assessment of Si and Al diffusion for the production of high Si and high Si-Al electrical steel

    A trend in the production of electrical steel is to increase the concentration of Si and Al (over 3 wt%) in order to reduce magnetic losses through increased electrical resistivity. This can hardly be done in early stages of the production process due to the appearance of brittle phases; however, a concentration increase of (Si, Al) can be reached by surface deposition of Si and/or Al, followed by diffusion into the bulk. Diffusion of Si and/or Al modifies substantially the mechanical and magnetic properties of the substrate and a study of the diffusion process leading to Fe-Si-Al alloys with homogeneous or inhomogeneous distribution of (Si, Al) is needed. The industrial production of these alloys requires models predicting the concentration profile of (Si, Al) resulting from the diffusion process and the changes of the mechanical and magnetic properties associated with the resulting concentration profiles of (Si, Al). This paper assesses the diffusion process using commercial software for the modelling of diffusion-controlled transformations. Experimental validation was made on some base alloys and results for the 3 wt% Si material are reported. Substrates were coated by dipping in a molten Al-25 wt% Si alloy, followed by annealing at different temperatures and times. The results show that Si concentration profiles can be accurately predicted. However, when considering both Si and Al diffusion their interaction causes important disagreements between experimental results and model calculations

  1. Enhanced light emission from Si nanocrystals produced using SiOx/SiO2 multilayered silicon-rich oxides

    Yoon, Jong-Hwan

    2015-07-01

    The light emission from Si nanocrystals (NCs) produced in SiO2 by annealing of SiOx/SiO2 multilayered silicon-rich oxide (SRO) is examined as a function of the SiOx layer thickness. Multilayered SRO structures are shown to produce a significant increase in emission intensities with a large redshift of spectra as compared with a single-layer SRO film. A multilayered SRO film with ∼6-nm thick SiO1.45 layers exhibits a 13-fold increase in the emission intensity with a redshift of ∼70 nm relative to a single-layer SiO1.45 SRO film with a thickness equivalent to the total SiO1.45 layer thickness in the multilayered film. The transmission electron microscopy analyses indicate that the enhancement of the emission intensity with the redshift of spectrum is caused by the enhanced aggregation of phase separated Si atoms in the former SiOx layers due to the hindering of interlayer diffusion of Si by the neighboring SiO2 layers.

  2. GeSi/Si Resonant Tunneling Diodes%GeSi/Si共振隧穿二极管

    郭维廉

    2008-01-01

    GeSi/Si共振隧穿二极管主要包括空穴型GeSi/Si RTD、应力型GeSi/Si RTD和GeSi/Si带间共振隧穿二极管三种结构.着重讨论了后两种GeSi/Si基RTD结构;指出GeSi/Si异质结的能带偏差主要发生在二者价带之间(即△Ev>△Ec),形成的电子势阱很浅,因此适用于空穴型RTD的研制;n型带内RTD只有通过应力Si或应力GeSi来实现,这种应力型RTD为带内RTD的主要结构;而带间GeSi/Si RITD则将成为更有应用前景的、性能较好的GeSi/Si RTD器件结构.

  3. Nitrogen doping effect upon hole tunneling characteristics of Si barriers in Si1-xGex/Si resonant tunneling diode

    Nitrogen atomic-layer (N AL) doping effects upon hole tunneling characteristics of double 4 nm-thick Si barriers in the strained Si1−xGex/Si(100) hole resonant tunneling diode (RTD) were investigated. At a Si cap layer on Si1−xGex(100) (x = 0.2 and 0.4) formed at 500 °C, it was found that NH3 reaction was drastically enhanced at 500 °C especially at the Si cap layer thickness less than 0.5 nm, and the fact indicates a possibility of significant intermixing at the Si/Si1−xGex heterointerface. From current–voltage characteristics of the RTDs, drastic current suppression by N AL doping in the Si barriers can be observed with typical degree of current suppression as high as 103–105 at − 10 mV. Moreover, it was found that N AL doping influences, not only upon such current suppression, but slightly upon negative differential conductance characteristics. - Highlights: • NH3 reaction enhancement on a thin Si cap layer on Si1−xGex(100). • Drastic current suppression by N atomic-layer doping in Si barriers. • N atomic-layer doping effect upon negative differential conductance characteristics

  4. Detección de perfiles cognitivos mediante WISC-IV en niños diagnosticados de TDAH: ¿Existen diferencias entre subtipos?

    Javier Fenollar-Cortés; Ignasi Navarro-Soria; Carla González-Gómez; Julia García-Sevilla

    2015-01-01

    El presente estudio explora si se puede obtener un perfil cognitivo específico para niños/as con TDAH a partir de la Escala de Inteligencia Wechsler para Niños Cuarta Edición (WISC-IV), y si ese perfil es capaz de diferenciar entre los subtipos clínicos de TDAH. Se seleccionó un grupo de control de 47 niños/as y otro grupo clínico de 86 niños/as diagnosticados/as con TDAH, éste último dividido a su vez en dos subgrupos de acuerdo a sus características clínicas. El grupo clínico se caracterizó...

  5. A interface entre Saúde Pública e Cibercultura

    Eduardo Jorge Sant Ana Honorato

    2014-01-01

    Este artigo, de caráter opinativo, propõe uma reflexão sobre como está a relação entre a cibercultura e a saúde pública e sua utilização como meio de pesquisa, e não apenas como instrumento. Cibercultura seria então uma nova forma de relação entre sujeitos. É justamente "através" e "pelas" relações sociais que os indivíduos adquirem habilidades técnicas e comunicação. Mudam-se as formas relacionais, os meios, mas os fins permanecem os mesmos: o de estarem em contato com outros humanos. Nas úl...

  6. Le respect : entre sentiment et volonté

    Dagneaux, Isabelle

    2013-01-01

    Fondement des relations humaines, le respect entre en jeu de façon particulière dans la relation de soin. D’où vient le respect, comment le cultiver et l’incarner ? Nous proposons d’y réfléchir avec le philosophe Vladimir Jankélévitch. Ce philosophe nous offre une conception du respect interpellante tant pour les relations de soins que pour les relations au quotidien.

  7. L'entrée des OGM en Europe

    Hériard Dubreuil, B.; Dissart, J. C.

    2006-01-01

    / Après la levée du moratoire sur les Ogm, cet article tente d'évaluer dans quelle mesure l'Union européenne a réglementé l'entrée des Ogm en Europe. Il identifie les tendances lourdes du système biotechnologique pour construire plusieurs scénarios et conclut à la segmentation durable du marché.

  8. El discurso de la transformación de la universidad, entre la universalidad y la particularidad

    Ana Leticia Tamayo Salcedo

    2009-01-01

    Full Text Available En el marco de los procesos de la globalización mundial, la demanda y el desafío que se le ha planteado a las universidades ha sido la de su reforma y transformación. Esta necesidad de transformación se ha ubicado en lo relativo a los aspectos curriculares y administrativos, que se plantean en el marco de las políticas educativas, a través del gobierno federal y las recomendaciones emitidas por los organismos internacionales, como el Banco Mundial, presentándose como el ideal de plenitud (la universalidad, es decir, como una propuesta hegemónica. El encuentro entre lo global y lo nacional o local -entiéndase, lo universal y lo particular respectivamente-, no está determinado a priori, si bien las recomendaciones emitidas por los organismos internacionales han operado como lineamientos de las políticas educativas mexicanas, no se puede hablar de una reproducción exacta, sino de su resignificación y adaptación en los contextos particulares dentro de los que pretende implementarse. Así la transformación de la universidad se constituye en un espacio de lucha y negociación constante, en donde se tejen articulaciones y antagonismos entre actores y discursos, en la disputa por la orientación que debe seguir la transformación de la educación superior.

  9. Resistência de união entre liga de níquel-cromo e cimentos resinosos

    FRANÇA Rodrigo de Oliveira

    1998-01-01

    Full Text Available O objetivo do trabalho foi a determinação da retentividade, por ensaio de tração, entre uma liga de níquel-cromo e cimentos resinosos (Comspan, Panavia Ex e All-Bond C & B, com quatro tratamentos superficiais (liso, microjateado, ataque eletrolítico e silicoater e armazenagem por 3 e 30 dias em solução de NaCl a 0,9%, a 37° C e termociclagem intercalada na segunda (a 5 e 55° C, por 1 minuto em cada banho, perfazendo 600 ciclos. Os corpos de prova eram discos, providos de alça fixadora entre si dois a dois. Os resultados permitiram concluir que: superfícies lisas conduzem a baixíssimas retentividades e tratadas com silicoater a altíssimos valores, com qualquer cimento e condição de armazenagem; Panavia Ex com superfícies microjateadas também conduz a altas retentividades; a maior retentividade foi obtida pela combinação silicoater/All-Bond C&B.

  10. Les Affinités électives de Goethe : entre science et littérature

    Bernard Joly

    2011-03-01

    Full Text Available Par leur titre même, Les affinités électives de Goethe renvoient à la doctrine chimique des rapports entre différents corps qui, à partir des travaux d’Etienne-François Geoffroy en 1718, s’impose comme théorie dominante dans la chimie du XVIIIe siècle. Goethe ne se contente pas d’une simple analogie entre les attirances amoureuses qui font et défont les couples et les opérations chimiques qui règlent les liaisons et les précipitations des substances chimiques. Son excellente connaissance de la tradition chimique et alchimique le conduit à considérer l’affinité comme une loi de la nature produisant aussi bien ses effets en chimie que chez les êtres vivants et dans le psychisme.The title of Goethe’s novel Elective Affinities refer to the chemical tenet of rapports between different bodies which, from Etienne-François Geoffroy’s works in 1718, emerge as a prevailing theory in the eighteenth-century chemistry. Goethe does not limit his views to the analogy between love attractions which made and break up couples and chimical processes which determine bonds and precipitations of chemical substances. His excellent knowledge of chemical and alchemical tradition leads him to consider affinity as a law of nature having effects in chemistry as well as in living being and into mind.

  11. Hybrid single mode lasers fabricated using Si/SiO2/SiON micromachined platforms

    Ksendzov, A.; Mansour, K.

    2003-01-01

    We have devised a hybridization scheme that, given suitable Fabri-Perot (F-P) ain medium, allows us to fabricate small, mechanically robust single frequency lasers in a wide spectral range, limited only by the transparency of the SiON material.

  12. Amistad entre machos adultos de monos aulladores negros y dorados

    Kowalewski, Martín M.

    2007-01-01

    Full Text Available El éxito reproductivo de los machos depende fundamentalmente del número de hembras que puedan fertilizar. Por lo tanto, los machos deberían competir activamente por las fertilizaciones. Sin embargo, en muchas especies de primates no-humanos, los machos conviven pacíficamente en grupos sociales. En este estudio exploramos las relaciones afiliativas entre machos de Alouatta caraya en la Isla Brasilera (27º 20’ S-58º 40’ W en el Noreste argentino. Dos grupos multimacho fueron estudiados durante 5 días por mes durante el año 2004. Definimos amistad como las interacciones afiliativas en díadas incluyendo proximidad, tolerancia durante la alimentación, interacciones de acicalamiento, y soporte en coaliciones. Por ejemplo, encontramos que los índices de asociación entre individuos basados en distancias y acicalamiento, difieren significativamente de lo esperado por azar a lo largo del año y en diferentes contextos comportamentales (p<0.05. Esto sugiere la existencia de pares de machos que se asociaron con mayor frecuencia que lo esperado por azar en ambos grupos. La existencia de afinidad social entre machos emparentados y no emparentados nos presenta nuevas preguntas en el estudio de la evolución de la amistad en primates no-humanos. Este tipo de estudios permite modelar nuevas ideas acerca de la historia evolutiva de la amistad en humanos.

  13. Factores socioculturales y consumo de drogas entre estudiantes universitarios costarricenses

    Jaime Alonso Caravaca Morera

    2015-01-01

    Full Text Available Investigación cuantitativa de tipo descriptiva-exploratoria, con diseño transversal que examinó el efecto moderador de ciertos factores socio-culturales en el consumo de drogas entre estudiantes universitarios en San José, Costa Rica. La muestra fue conformada por 126 mujeres y 124 hombres de una universidad pública de forma no probabilística. Fue elaborado un cuestionario con cinco escalas ya validadas, que interrogaba sobre la influencia del grupo de pares, las relaciones familiares, el entretenimiento, la espiritualidad y el consumo de drogas. Se utilizó el programa SPSS versión 18 para el análisis estadístico. Se estableció que el 98,4% de los estudiantes reportaron tener por lo menos un amigo que consumía drogas, las drogas más consumidas fueron alcohol, tabaco y marihuana. Se estableció asociación significativa entre algunos factores académicos y culturales con el consumo de drogas legales e ilegales. Se concluye que deben ser implementadas estrategias preventivas considerando la influencia de los factores culturales entre los estudiantes universitarios.

  14. Microwave joining of SiC

    Silberglitt, R.; Ahmad, I. [FM Technologies, Inc., Fairfax, VA (United States); Black, W.M. [George Mason Univ., Fairfax, VA (United States)] [and others

    1995-05-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on optimization of time-temperature profiles, production of SiC from chemical precursors, and design of new applicators for joining of long tubes.

  15. Emission efficiency limit of Si nanocrystals

    Limpens, R.; Luxembourg, S.L.; Weeber, A.W.; Gregorkiewicz, T.

    2016-01-01

    One of the important obstacles on the way to application of Si nanocrystals for development of practical devices is their typically low emissivity. In this study we explore the limits of external quantum yield of photoluminescence of solid-state dispersions of Si nanocrystals in SiO2. By making use

  16. High Q SiC microresonators

    Cardenas, Jaime; Zhang, Mian; Phare, Christopher T.; Shah, Shreyas Y.; Poitras, Carl B.; Lipson, Michal

    2013-01-01

    We demonstrate photonic devices based on standard 3C SiC epitaxially grown on silicon. We achieve high optical confinement by taking advantage of the high stiffness of SiC and undercutting the underlying silicon substrate. We demonstrate a 20 um radius suspended microring resonator with Q of 18000 fabricated on commercially available SiC-on-silicon substrates.

  17. An introduction to the New SI

    Knotts, Sandra; Phillips, William D

    2015-01-01

    Plans are underway to redefine the International System of Units (SI) around 2018. The New SI specifies the values of certain physical constants to define units. This article explains the New SI in a way that could be used to present it to high-school physics classes.

  18. Effects of thermal annealing on photoluminescence of Si+/C+ implanted SiO2 films

    Chen, Yin-Yu; Chao, Der-Sheng; Tsai, Hsu-Sheng; Liang, Jenq-Horng

    2016-04-01

    The mechanisms of photoluminescence (PL) originating from Si+/C+ implanted SiO2 are still unclear and need to be clarified. Thus, the purpose of this study is to thoroughly investigate the effects of ion implantation and post-annealing temperature on microstructures and PL characteristics of the Si+/C+ implanted SiO2 films. A comparative analysis was also conducted to clarify the different optical properties between the Si+ and Si+/C+ implanted SiO2 films. In this study, thermally-grown SiO2 films on Si substrates were used as the matrix materials. The Si+ ions and C+ ions were separately implanted into the SiO2 films at room temperature. After ion implantation, the post-annealing treatments were carried out using the furnace annealing (FA) method at various temperatures (600-1100 °C) for 1 h in a N2 ambient. The PL characteristics of the implanted SiO2 films were analyzed using a fluorescence spectrophotometer. The results revealed that the distinct PL peaks were observed at approximately 310, 450 and 650 nm in the Si+-implanted SiO2 films, which can be attributed to the defects, the so-called oxygen deficiency centers (ODCs) and non-bridging oxygen hole centers (NBOHCs), in the materials. In contrast to the Si+ ion implantation, the SiO2 films which were sequentially implanted with Si+ and C+ ions and annealed at 1100 °C can emit white light corresponding to the PL peaks located at around 420, 520 and 720 nm, those can be assigned to the Si-C bonding, C-C graphite-like structure (sp2), and Si nanocrystals, respectively. Moreover, a correlation between the optical properties, microstructures, and bonding configurations of the Si+/C+ implanted SiO2 films was also established in this study.

  19. Helium gas permeability of low activation SiC/SiC composite

    Permeability of helium gas in SiC fiber reinforced SiC composite (SiC/SiC composite) was measured by using a vacuum apparatus consisting two chambers. The SiC/SiC samples were prepared by different methods; polymer infiltration and pyrolysis (PIP), PIP and melt impregnation (MI), hot pressing (HP) and liquid phase sintering (LPS). The measurement of permeability was carried out with pressure of helium ranging from 102 to 105 Pa at room temperature. The permeability of the sample made by LPS method was several orders of magnitude lower than those of the other SiC/SiC composites. The lowest permeability, 4 x 10-11 m2s-1, was observed for the SiC/SiC composite made by LPS using SiC fibers and nano powder of β-SiC. The largest permeability, 5 x 10-5 m2s-1, was observed for the SiC/SiC composite made by PIP. The permeability of the SiC/SiC composite depended on the structures of fiber bundle and matrix, and roughly corresponded to the microscopic structures, i.e. pores and cracks. (author)

  20. Si@SiOx/graphene hydrogel composite anode for lithium-ion battery

    Bai, Xuejun; Yu, Yueyang; Kung, Harold H.; Wang, Biao; Jiang, Jianming

    2016-02-01

    A porous 3D graphene hydrogel (GH) composite embedded with Si nanoparticles coated with an ultrathin SiOx layer (Si@SiOx/GH) is successfully synthesized using a solution-based self-assembly process. The thickness of the SiOx coating, formed by an ozone treatment of the 30-50 nm diameter Si particles, increases with the treatment temperature, and its formation results in the presence of Si2+ and Si4+ on the surface of the Si nanoparticles. The GH provides an electrically conducting network of interconnecting, micron-size open cells bounded by ultrathin stacked graphene sheets onto which the coated Si nanoparticles are dispersed. The agglomeration among the Si particles decreases with increasing extent of surface oxidation. Electrodes constructed with the Si@SiOx/GH containing 71 wt.% Si@SiOx exhibit a stable storage capacity of 1020 mAh g-1 at 4 A g-1 and 1640 mAh g-1 after 140 cycles at 0.1 A g-1. The outstanding electrochemical performance can be attributed to the porous, open cell 3D structure of GH, which provides a large internal space and flexible and electrically conductive graphenic matrix that can accommodate volumetric changes of Si nanoparticles and a highly porous 3D structure of high specific surface area that allows rapid diffusion of Li-ions and easy penetration of electrolyte.

  1. One-step deposition of ultrafiltration SiC membranes on macroporous SiC supports

    König, Katja; Boffa, Vittorio; Buchbjerg, Bjarke;

    2014-01-01

    We fabricated nearly defect-free SiC membranes for potential ultrafiltration applications by conducting pyrolysis of allylhydrido polycarbosilane in the presence of submicron α-SiC particles. The SiC membranes were developed on commercial macroporous SiC supports by a low-temperature-process in...

  2. Laser cladding of Al-Si/SiC composite coatings : Microstructure and abrasive wear behavior

    Anandkumar, R.; Almeida, A.; Vilar, R.; Ocelik, V.; De Hosson, J.Th.M.

    2007-01-01

    Surface coatings of an Al-Si-SiC composite were produced on UNS A03560 cast Al-alloy substrates by laser cladding using a mixture of powders of Al-12 wt.% Si alloy and SiC. The microstructure of the coatings depends considerably on the processing parameters. For a specific energy of 26 MJ/m2 the mic

  3. Irradiation project of SiC/SiC fuel pin 'INSPIRE': Status and future plan

    After the March 11 Disaster in East-Japan, Research and Development towards Ensuring Nuclear Safety Enhancement for LWR becomes a top priority R and D in nuclear energy policy of Japan. The role of high temperature non-metallic materials, such as SiC/SiC, is becoming important for the advanced nuclear reactor systems. SiC fibre reinforced SiC composite has been recognised to be the most attractive option for the future, now, METI fund based project, INSPIRE, has been launched as 5-year termed project at OASIS in Muroran Institute of Technology aiming at early realisation of this system. INSPIRE is the irradiation project of SiC/SiC fuel pins aiming to accumulate material, thermal, irradiation effect data of NITE-SiC/SiC in BWR environment. Nuclear fuel inserted SiC/SiC fuel pins are planned to be installed in the Halden reactor. The project includes preparing the NITE-SiC/SiC tubes, joining of end caps, preparation of rigs to control the irradiation environment to BWR condition and the instruments to measure the condition of rigs and pins in operation. Also, basic neutron irradiation data will be accumulated by SiC/SiC coupon samples currently under irradiation in BR2. The output from this project may present the potentiality of NITE-SiC/SiC fuel cladding with the first stage fuel-cladding interaction. (authors)

  4. High energy electron-beam irradiation effects in Si-SiOx structures

    Nesheva, D.; Dzhurkov, V.; Šćepanović, M.; Bineva, I.; Manolov, E.; Kaschieva, S.; Nedev, N.; Dmitriev, S. N.; Popović, Z. V.

    2016-02-01

    Homogeneous SiOx films (x=1.3, 200 nm and 1000 nm thick) and composite a-Si-SiOy films (y ∼ 1.80) containing amorphous Si nanoparticles have been prepared on crystalline (c-Si) substrate. A part of the films was irradiated at temperature below 50°C by 20 MeV electrons with two different fluences (7.2x1014 and 1.44x1015 el.cm-2). Atomic force microscopy (AFM), Raman spectroscopy and capacitance (conductance) - voltage (C(G)-V) measurements on Al/c-Si/SiOx/Al or Al/c-Si/(a-Si-SiOy)/Al structures were used to get information about the irradiation induced changes in the surface morphology, the phase composition in the film bulk and at the Si-SiOx interface. The AFM results show that the electron irradiation decreases the film surface roughness of the films annealed at 250°C. The Raman scattering data imply appearance of amorphous silicon phase and some structural changes in the oxide matrix of the homogeneous SiOx films. In the composite films electron beam stimulated decrease of the defects at the a-Si/SiOy interface has been assumed. The initial C(G)-V results speak about electron induced formation of electrically active defects in the SiOy matrix of the composite films.

  5. SiO2/Si Interfacial Degradation and the Role of Oxygen Interstitials

    Devine, R.

    1996-01-01

    High temperature annealing of Si/SiO2/Si structures in inert atmospheres is known to result in degradation of the oxide layer and electron and hole trap creation. We review our understanding of the basic mechanisms active in such structures that can result in point defect generation. Using electron spin resonance and infra-red absorption data, we demonstrate that in low oxygen content Si substrates (float zone) annealing of Si/SiO2/Si structures at high temperatures results in a gettering of ...

  6. X-ray interference topography investigation of Si/GexSi1-x/Si(001) heterosystem

    In x-ray topographs of Si/GexSi1-x/Si(001) heterosystems, the intensity variations, which are associated with inhomogeneous GeSi thickness, are observed. The layers of GeSi and Si were grown by molecular beam epitaxy. The growth conditions preserving the pseudomorphic state of the intermediate SiGe layer from misfit dislocation appearance were kept. The topographs were recorded using a spherically bent monochromator as well as a flat one. The observed contrast peculiarities are established to be Moire (translation fault) fringes. The displacement of interference fringes due to the crystal angular position variation is observed. For Pendelloesung maxima, the dependence of their angular positions on nondiffracted layer thickness is established. The image simulated in the framework of semikinematical approach demonstrates the main contrast peculiarities observed in the topograph

  7. Abrupt GaP/Si hetero-interface using bistepped Si buffer

    Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O. [UMR FOTON, CNRS, INSA Rennes, Rennes F-35708 (France); Stodolna, J.; Ponchet, A. [CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 04 (France); Bahri, M.; Largeau, L.; Patriarche, G. [Laboratoire de Photonique et Nanostructures, CNRS UPR 20, Route de Nozay, Marcoussis 91460 (France); Magen, C. [LMA, INA-ARAID, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

    2015-11-09

    We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.

  8. Si quantum dot structures and their applications

    Shcherbyna, L.; Torchynska, T.

    2013-06-01

    This paper presents briefly the history of emission study in Si quantum dots (QDs) in the last two decades. Stable light emission of Si QDs and NCs was observed in the spectral ranges: blue, green, orange, red and infrared. These PL bands were attributed to the exciton recombination in Si QDs, to the carrier recombination through defects inside of Si NCs or via oxide related defects at the Si/SiOx interface. The analysis of recombination transitions and the different ways of the emission stimulation in Si QD structures, related to the element variation for the passivation of surface dangling bonds, as well as the plasmon induced emission and rare earth impurity activation, have been presented. The different applications of Si QD structures in quantum electronics, such as: Si QD light emitting diodes, Si QD single union and tandem solar cells, Si QD memory structures, Si QD based one electron devices and double QD structures for spintronics, have been discussed as well. Note the significant worldwide interest directed toward the silicon-based light emission for integrated optoelectronics is related to the complementary metal-oxide semiconductor compatibility and the possibility to be monolithically integrated with very large scale integrated (VLSI) circuits. The different features of poly-, micro- and nanocrystalline silicon for solar cells, that is a mixture of both amorphous and crystalline phases, such as the silicon NCs or QDs embedded in a α-Si:H matrix, as well as the thin film 2-cell or 3-cell tandem solar cells based on Si QD structures have been discussed as well. Silicon NC based structures for non-volatile memory purposes, the recent studies of Si QD base single electron devices and the single electron occupation of QDs as an important component to the measurement and manipulation of spins in quantum information processing have been analyzed as well.

  9. Entre propietarios y migrantes: los encuentros y desencuentros entre Colonos y Aguarunas en el alto mayo”

    Kenneth E. Garces Montes

    2013-10-01

    Full Text Available La dinámica de conflictos entre colonos y nativos en el Alto Mayo, ha dado como producto continuosenfrentamientos entre caseríos de colonos y comunidades nativas colindantes, así como una seriede procesos judiciales por “usurpación de tierras”, en los cuales no se logra una ejecución efectiva dela sentencia a pesar que esta sea favorable a los nativos, debido a la distancia social que existe entrelos operadores estatales y el conflicto real. Por su parte los mecanismos de convivencia entre colonosy nativos se inician mediante el alquiler de tierras, diseñada como una fórmula temporal para quelos colonos se retiren una vez vencido el plazo del alquiler, sin embargo la ampliación de los plazosprovoca que los mismos adquieran vocación de permanencia.Una serie de actores, de primer, segundo y tercer orden interactúan alrededor de las dos dinámicasde relacionamiento mencionadas; tales como las ONGs, el Estado, organizaciones indígenas, einclusive mafias de traficantes de tierras. Ante esta realidad tan compleja conviene hacer el ejerciciode plantear propuestas de adaptabilidad (o subsistencia de las comunidades nativas, en las quese visualice la supervivencia de lo local frente a lo global en lo que a demarcación de tierras de lascomunidades nativas se refiere.

  10. Relación entre el consumo de drogas y maltrato infantil entre estudiantes universitarios de la universidad en Colombia

    Monica Rosaura Garcia Baquero

    2015-01-01

    Full Text Available Esta investigación examina la relación entre el uso de drogas en estudiantes de una Universidad Pública en Villavicencio, Colombia, y su relación con el maltrato durante la niñez, utilizando como referente teórico la perspectiva bioecológica. Estudio exploratorio retrospectivo, con una muestra de 313 estudiantes de pregrado. El 10.2% de los encuestados refiere haber sido maltratado en la Infancia y la violencia de mayor uso fue la violencia física seguida de la violencia psicológica. El 56.9% de las estudiantes encuestados han consumido sustancias psicoactivas en algún momento de la vida, y su inicio entre los 13 y los 18 años. Se evidencia maltrato en la infancia con manifestaciones de agresiones físicas, al igual que el consumo de sustancias psicoactivas, pero no se observa una relación estadísticamente significativa entre maltrato durante la infancia y el consumo de sustancias psicoactivas en la muestra estudiada.

  11. Current–voltage studies on -FeSi2/Si heterojunction

    A Datta; S Kal; S Basu

    2000-08-01

    – characteristics of both -FeSi2/n-Si and -FeSi2/p-Si were studied at room temperature. The junctions were formed by depositing Fe on Si selectively followed by thermal annealing and some samples were later treated by pulsed laser. Temperature of thermal annealing and diode area were also varied. – studies on all these samples were done and ideality factors were computed. Results obtained were interpreted.

  12. Stability analysis of SiO2/SiC multilayer coatings

    The stability behaviours of SiC coatings and SiO2/SiC coatings in helium with little impurities are studied by HSC Chemistry 4.1, the software for analysis of Chemical reaction and equilibrium in multi-component complex system. It is found that in helium with a low partial pressure of oxidative impurities under different total pressure, the key influence factor controlling Tcp of SiC depends is the partial pressure of oxidative impurities; Tcp of SiC increases with the partial pressure of oxidative impurities. In helium with a low partial pressure of different impurities, the key influence factor of Tcs of SiO2 are both the partial pressure of impurities and the amount of impurities for l mol SiO2; Tcs of SiO2 increases with the partial pressure of oxidative impurities at the same amount of the impurities for 1 mol SiO2 while it decreases with the amount of the impurities for 1 mm SiO2 at the same partial pressure of the impurities. The influence of other impurities on Tcp of SiC in He-O2 is studied and it is found that CO2, H2O and N-2 increase Tcp of SiC in He-O2 while H2, CO and CH4 decrease Tcp of SiC He-O2. When there exist both oxidative impurities and reductive impurities, their effect on Tcs of SiO2 can be suppressed by the other. In HTR-10 operation atmosphere, SiO2/SiC coatings can keep stable status at higher temperature than SiC coatings, so SiO2/SiC coatings is more suitable to improve the oxidation resistance of graphite in HTR-10 operation atmosphere compared with SiC coatings. (authors)

  13. In-situ observation of crack propagation in SiC/SiC by HVEM

    Full text of publication follows: SiC/SiC composites are candidate materials for fusion applications due to their potential to retain strength and exhibit tough behavior at elevated temperatures. The irradiation stability of monolithic beta-SiC has been well studied and the mechanical property evaluation of SiC/SiC composites has been started under the standard test method of Continuous Fiber reinforced Ceramic Composites (CFCC's). It is important to know the initiation, coalescence and growth of crack in SiC/SiC composites. However there are no good tests for measuring the crack propagation at fracture of SiC/SiC composites than before. After mechanical testing, microstructure analysis of fracture region in SiC/SiC composites by Focused Ion Beam (FIB) was done, though the artifact during TEM specimen preparation would be introduced sometime. Recently we successfully developed a piezo driven nano indenting equipment for observation of crack propagation in SiC/SiC under the irradiation by High Voltage Electron Microscope (HVEM). Preliminary result of in-situ observation of shear crack propagation at the interface between SiC fiber and SiC matrix by HVEM shows a good agreement with the result of out situ experiment by using the cross section TEM specimen at the shear fracture interface between SiC fiber and SiC matrix prepared by FIB after the fiber pushing out testing by the nano indenter. The shear crack initiated and propagated at the interface between SiC matrix and carbon coated layer on the SiC fiber. Results of in-situ observation of crack propagation at W and SiC joining interface will be also presented. (authors)

  14. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    Dobrovolskiy, S.; Yakshin, A.E.; Tichelaar, F.D.; Verhoeven, J.; Louis, E.; Bijkerk, F.

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10–20 nm were produced by sequential deposition of Si and implantation of 1 keV View the MathML source ions. Only about 3% of the implanted carbon was transferred into the SiC, with a thin, 0.5–1 nm, buried SiC layer being fo

  15. Swarm Intelligence (SI) in Manufacturing

    Molinuevo, Javier Toral

    2010-01-01

    Manufacturing is a field of Engineering which is constantly changing. Due to this fact more and more complicated problems appear and have to be solved by engineers. Some of them are difficult to solve by usual numerical methods, as equations, so a new area is developing at present using Artificial Intelligence (AI) techniques.There are many different tools like Genetic Algorithms, Fuzzy Logic Systems… but in this thesis we are going to focus on the Swarm Intelligence (SI) which tries to mimic...

  16. Effect of Si interface surface roughness to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor

    Hasanah, Lilik; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru; Nandiyanto, Asep Bayu Dani; Murakami, Hideki; Khairrurijal

    2016-02-01

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  17. Active Oxidation of SiC

    Jacobson, Nathan S.; Myers,Dwight L.; Harder, Bryan J.

    2011-01-01

    The high temperature oxidation of silicon carbide occurs in either a passive or active mode, depending on temperature and oxygen potential. Passive oxidation forms a protective oxide film which limits attack of the SiC:SiC(s) + 3/2 O2(g) = SiO2(s) + CO(g.) Active oxidation forms a volatile oxide and leads to extensive attack of the SiC: SiC(s) + O2(g) = SiO(g) + CO(g). The transition points and rates of active oxidation are a major issue. Previous studies are reviewed and the leading theories of passive/active transitions summarized. Comparisons are made to the active/passive transitions in pure Si, which are relatively well-understood. Critical questions remain about the difference between the active-to-passive transition and passive-to-active transition. For Si, Wagner [2] points out that the active-to-passive transition is governed by the criterion for a stable Si/SiO2 equilibria and the passive-to-active transition is governed by the decomposition of the SiO2 film. This suggests a significant oxygen potential difference between these two transitions and our experiments confirm this. For Si, the initial stages of active oxidation are characterized by the formation of SiO(g) and further oxidation to SiO2(s) as micron-sized rods, with a distinctive morphology. SiC shows significant differences. The active-to-passive and the passive-to-active transitions are close. The SiO2 rods only appear as the passive film breaks down. These differences are explained in terms of the reactions at the SiC/SiO2 interface. In order to understand the breakdown of the passive film, pre-oxidation experiments are conducted. These involve forming dense protective scales of 0.5, 1, and 2 microns and then subjecting the samples with these scales to a known active oxidation environment. Microstructural studies show that SiC/SiO2 interfacial reactions lead to a breakdown of the scale with a distinct morphology.

  18. Effect of Si interface surface roughness to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor

    Hasanah, Lilik, E-mail: lilikhasanah@upi.edu; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru [Department of Physics Education, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Nandiyanto, Asep Bayu Dani [Department Kimia, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Murakami, Hideki [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Khairrurijal [Physics of Electronic Materials Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia)

    2016-02-08

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  19. La visión del otro entre igualdad y diferencia

    Betina Lilián Prenz

    2004-12-01

    Full Text Available Una innegable evidencia rige el universo humano; nos referimos a la irreducible pluralidad de culturas que lo domina. Dado que las culturas son el horizonte de sentido sin el cual toda experiencia humana sería impensable, es decir, el fondo que hace posible la originaria relación del individuo con el mundo (y cada una de las cuales encierra en sí su propia concepción de lo que somos como hombres, no podemos no tomar en cuenta, pues, la multiplicidad de fisonomías con las que se nos presenta el rostro humano, y con ello, el conjunto de problemas, tanto teóricos como prácticos, que semejante cuestión de la diferencia, o si queremos, de la alteridad, lleva consigo. Si una pregunta pudiese contenerlas todas, plantearíamos, en términos muy generales y que permitiesen ulteriores ra- mificaciones, la siguiente cuestión: si las culturas, múltiples y diferentes, representan el ineludible horizonte de significatividad de la experiencia de los hombres y si éstas son tan radicalmente diferentes, como radicalmente diferentes son los hombres que las habi- tan, Ecómo comportarnos entonces con los demás, o sea, en nuestras relaciones con šel otro’? Naturalmente, hay muchas formas de responder a esta pregunta, por ejemplo, en función o de la perspectiva que la enfoca o del aspecto que en ella preferimos privilegiar: en la amplia gama de cuestiones que semejante pregunta implica, podemos, en efecto, distinguir entre las que pertenecen a un plano axiológico (que tiene que ver con los juicios de valor, con términos como superioridad, inferioridad, relatividad, o a un plano praxeológico (en el que es posible hablar de asimilación del otro o al otro, pero también a un plano epistemológico (que contiene la cuestión fundamental de la comprensión del otro, etc. Entre las varias posibilidades, nosotros tomaremos aquí en cuenta una que intenta no perder de vista los diferentes ejes alrededor de los cuales gira la pregunta misma: se tra- ta de

  20. Porous SiC/SiC composites development for industrial application

    Silicon carbide (SiC) is promising structural materials in nuclear fields due to an excellent irradiation resistance and low activation characteristics. Conventional SiC fibers reinforced SiC matrix (SiC/SiC composites) fabricated by liquid phase sintering (LPS-SiC/SiC composites) have been required high cost and long processing time. And microstructure and mechanical property data of finally obtained LPS-SiC/SiC composites are easily scattered, because quality of the composites depend on personal skill. Thus, conventional LPS-SiC/SiC composites are inadequate for industrial use. In order to overcome these issues, the novel “porous SiC/SiC composites” have been developed by means of liquid phase sintering fabrication process. The composites consist of porous SiC matrix and SiC fibers without conventional carbon interfacial layer. The composites don’t have concerns of the degradation interfacial layer at the severe accident. Porous SiC/SiC composites preform was prepared with a thin sheet shape of SiC, sintering additives and carbon powder mixture by tape casting process which was adopted because of productive and high yielding rate fabrication process. The preform was stacked with SiC fibers and sintered in hot-press at the high temperature in argon environment. The sintered preform was decarburized obtain porous matrix structure by heat-treatment in air. Moreover, mechanical property data scattering of the obtained porous SiC/SiC composites decreased. In the flexural test, the porous SiC/SiC composites showed pseudo-ductile behavior with sufficient strength even after heat treatment at high temperature in air. From these conclusions, it was proven that porous SiC/SiC composites were reliable material at severe environment such as high temperature in air, by introducing tape casting fabrication process that could produce reproducible materials with low cost and simple way. Therefore development of porous SiC/SiC composites for industrial application was

  1. Lattice dislocation in Si nanowires

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.co [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Taha, H.T. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)

    2009-12-15

    Modified formulas were used to calculate lattice thermal expansion, specific heat and Bulk modulus for Si nanowires with diameters of 115, 56, 37 and 22 nm. From these values and Gruneisen parameter taken from reference, mean lattice volumes were found to be as 20.03 A{sup 3} for the bulk and 23.63, 29.91, 34.69 and 40.46 A{sup 3} for Si nanowire diameters mentioned above, respectively. Their mean bonding length was calculated to be as 0.235 nm for the bulk and 0.248, 0.269, 0.282 and 0.297 nm for the nanowires diameter mentioned above, respectively. By dividing the nanowires diameter on the mean bonding length, number of layers per each nanowire size was found to be as 230, 104, 65 and 37 for the diameters mentioned above, respectively. Lattice dislocations in 22 nm diameter wire were found to be from 0.00324 nm for the 1st central lattice to 0.2579 nm for the last surface lattice. Such dislocation was smaller for larger wire diameters. Dislocation concentration found to change in Si nanowires according to the proportionalities of surface thickness to nanowire radius ratios.

  2. Ion implantation and diffusion of Al in a SiO{sub 2}/Si system

    La Ferla, A. [Catania Univ. (Italy). Ist. di Fisica; Galvagno, G. [Catania Univ. (Italy). Ist. di Fisica; Rinaudo, S. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Raineri, V. [CNR-IMETEM, Stradale Primosole 50, 95100 Catania (Italy); Franco, G. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Camalleri, M. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Gasparotto, A. [Dipartimento di Fisica, via Marzolo 8, 35131 Padova (Italy); Carnera, A. [Dipartimento di Fisica, via Marzolo 8, 35131 Padova (Italy); Rimini, E. [Catania Univ. (Italy). Ist. di Fisica

    1996-08-01

    The diffusion and segregation of ion implanted Al in SiO{sub 2} and Si layers were studied for several experimental conditions. Al ions were implanted into SiO{sub 2}, Si and through a SiO{sub 2} layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4.10{sup 14}-1.10{sup 15} cm{sup -2}). The Al diffusion coefficient in SiO{sub 2} was measured at 1200 C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO{sub 2} capping layer, but segregate at the SiO{sub 2}/Si interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the SiO{sub 2}/Si system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data. (orig.).

  3. Ion implantation and diffusion of Al in a {SiO 2}/{Si} system

    La Ferla, A.; Galvagno, G.; Rinaudo, S.; Raineri, V.; Franco, G.; Camalleri, M.; Gasparotto, A.; Carnera, A.; Rimini, E.

    1996-08-01

    The diffusion and segregation of ion implanted Al in SiO 2 and Si layers were studied for several experimental conditions. Al ions were implanted into SiO 2, Si and through a SiO 2 layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4 × 10 14-1 × 10 15 cm -2). The Al diffusion coefficient in SiO 2 was measured at 1200°C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO 2 capping layer, but segregate at the {SiO 2}/{Si} interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the {SiO 2}/{Si} system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data.

  4. Ion implantation and diffusion of Al in a SiO2/Si system

    The diffusion and segregation of ion implanted Al in SiO2 and Si layers were studied for several experimental conditions. Al ions were implanted into SiO2, Si and through a SiO2 layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4.1014-1.1015 cm-2). The Al diffusion coefficient in SiO2 was measured at 1200 C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO2 capping layer, but segregate at the SiO2/Si interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the SiO2/Si system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data. (orig.)

  5. Hierarchical Cd4SiS6/SiO2 Heterostructure Nanowire Arrays

    Liu Jian

    2009-01-01

    Full Text Available Abstract Novel hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays were fabricated on silicon substrates by a one-step thermal evaporation of CdS powder. The as-grown products were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Studies reveal that a typical hierarchical Cd4SiS6/SiO2 heterostructure nanowire is composed of a single crystalline Cd4SiS6 nanowire core sheathed with amorphous SiO2 sheath. Furthermore, secondary nanostructures of SiO2 nanowires are highly dense grown on the primary Cd4SiS6 core-SiO2 sheath nanowires and formed hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays which stand vertically on silicon substrates. The possible growth mechanism of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays is proposed. The optical properties of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays are investigated using Raman and Photoluminescence spectroscopy.

  6. Modification of eutectic Si in Al–Si alloys with Eu addition

    Al–5 wt.% Si-based alloys with 0.05 wt.% Eu addition were produced by controlled sand-casting and melt-spinning, respectively. The modification of eutectic Si caused by 0.05 wt.% Eu addition was investigated by thermal analysis, differential scanning calorimetry and multi-scale microstructure characterization techniques. In the case of controlled sand-casting, 0.05 wt.% Eu addition was found to modify the eutectic Si into a fibrous morphology. Multiply twinned Si particles were observed within eutectic Si. Furthermore, the Al2Si2Eu phase was also observed both in the vicinity of eutectic Si and within eutectic Si, which was believed to hinder Si growth. In the case of melt-spun samples, nanometer-sized Al2Si2Eu phases were observed. However, after controlled cooling in a differential scanning calorimeter, multiply twinned Si particles were observed. The formation of multiply twinned Si particles was attributed to the adsorption of Eu atoms along the 〈1 1 2〉Si growth direction of Si and at the intersection of two {1 1 1}Si facets. Twinning was observed in both fundamentally different casting processes: controlled sand-casting and melt-spinning. This is fully consistent with the well-known poisoning of the twin plane re-entrant edge and the impurity-induced twinning modification mechanisms

  7. Comparison of the thermal stabilities of NiSi films in Ni/Si, Ni/Pd/Si and Ni/Pt/Si systems

    Wang, R N

    2003-01-01

    The effects of different interlayer materials (Pd and Pt) deposited between Ni films and Si substrates on the NiSi thermal stability are discussed. Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si and Ni sub 0 sub . sub 9 sub 4 sub 5 Pt sub 0 sub . sub 0 sub 5 sub 5 Si solid solutions were formed when the samples were annealed at high temperatures and the lattice parameters of Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si were calculated according to Vegard's law. The NiSi thermal stability was enhanced by interposing a Pd or Pt interlayer, and the sample with the Pt interlayer had the highest NiSi thermal stability among all the samples studied. This is attributed to the reduction of the interface energy between NiSi and Si substrates and the decrease of the driving force for the nucleation of NiSi sub 2 , induced by formation of the NiSi(200) preferred orientation and the solid solution respectively.

  8. Preparation of biomorphic SiC ceramics

    Egelja A.

    2008-01-01

    Full Text Available This paper deals with a new method for producing non-oxide ceramic using wood as a template. SiC with a woodlike microstructure has been prepared by carbothermal reduction reactions of Tilia wood/TEOS composite at 1873K. The porous carbon preform was infiltrated with TEOS (Si(OC2H54, as a source of silica, without pressure at 298K. The morphology of resulting porous SiC ceramics, as well as the conversion mechanism of wood to SiC ceramics, have been investigated by scanning electron microscopy (SEM/EDS and X-ray diffraction analysis (XRD. Obtained SiC ceramics consists of β-SiC with traces of α-SiC.

  9. Differential cross sections measurement of 28Si(p,p/γ)28Si and 29Si(p,p/γ)29Si reactions for PIGE applications

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.

    2016-03-01

    Differential cross sections for gamma-ray emission from the 28Si(p,p/γ)28Si (Eγ = 1779 keV) and the 29Si(p,p/γ)29Si (Eγ = 1273 keV) nuclear reactions were measured in the energy range of 2.0-3.2 MeV and 2.0-3.0 MeV, respectively. The thin Si targets were prepared by evaporating natural SiO onto self-supporting Ag films. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. The great advantage of this work is that differential cross sections were obtained with a procedure irrespective of absolute value of the collected beam charge.

  10. L’image sonore contemporaine : entre misère symbolique et imaginaire sonore

    Vincent Tiffon

    2007-05-01

    Full Text Available L’histoire de la musique peut s’écrire comme l’évolution progressive mais déterminante de deux grands paradigmes technologiques, celui de l’écriture et celui du son. L’enregistrement sonore modifie en profondeur l’économie de la musique en inventant notamment de nouveaux modes d’invention du sonore et de nouvelles pratiques d’écoute du sonore. On élargit alors le domaine du musical en inventant l’image sonore. À l’instar des autres arts de studio, la photographie, la cinématographie, la vidéo…, la phonographie prend le réel comme matériau immédiat. L’effet de réalité qui en résulte conduit au glissement progressif de la musique comme objet cultuel (avant le xive siècle, à la musique comme objet industriel (depuis 1970 en passant par la musique comme objet culturel (entre le xive siècle et le xxe siècle ; ce faisant, le risque d’une « désorientation » est bien réel. D’où une cartographie floue entre culture, art et phénomènes de société. L’image sonore semble s’inscrire entre « misère symbolique » et imaginaire, entre l’industrie musicale et l’avant-garde.The history of music can be written as the gradual yet decisive evolution of two great technological paradigms: the paradigms of writing and of sound. Sound recording has profoundly altered the organization of music, notably through the invention of new modes of sound invention and new practices of listening to sound phenomena. It is precisely at this point that the field of music has been widened by the invention of the sound image. After the fashion of the other arts of the studio (photography, cinematography, video and so on, phonography has reality itself as its unmediated material. The resulting reality effect has led to the gradual shift from music as liturgical object (before the 14th century to music as industrial object (since 1970 via music as cultural object (between the 14th century and the 20th century. In

  11. Deformation effects in the 28Si + 12C and 28Si + 28Si reactions

    C Bhattacharya; M Rousseau; C Beck; V Rauch; R M Freeman; R Nouicer; F Haas; O Dorvaux; K Eddahbi; P Papka; O Stezwski; S Szilner; D Mahboub; A Szanto De Toledo; A Hachem; E Martin; S J Sanders

    2001-07-01

    The possible occurrence of highly deformed configurations is investigated in the 40Ca and 56Ni di-nuclear systems as formed in the 28Si + 12C, 28Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8Be cluster emission of a binary nature.

  12. Relaciones entre el Congreso Nacional y el Poder Judicial: La Importancia de la Apertura

    Sebastián Soto Velasco

    2007-01-01

    Full Text Available El presente trabajo analiza las relaciones entre el Congreso Nacional y el Poder Judicial a través de dos instituciones existentes en nuestro ordenamiento: el proceso de nombramiento de Ministros de la Corte Suprema y los informes que esta última envía al Congreso Nacional en ciertos proyectos de ley. En el caso de las nominaciones de Ministros a la Corte Suprema se estudia como ha operado el sistema desde la incorporación del Senado en 1997 hasta el año 2005. Se analiza cómo la transparencia del proceso, la posibilidad de conocer la historia profesional del nominado y audiencias abiertas contribuirían a incentivar una decisión centrada en criterios de calidad. El documento también se centra en el contenido y la influencia de los informes que envía la Corte Suprema al Congreso Nacional con ocasión de la tramitación de proyectos de ley que contienen normas que modifican la organización o atribuciones de los tribunales de justicia. En esta instancia, permitir el acceso a los informes también tendría positivas consecuencias. En definitiva, aunque hay otras vías de comunicación entre el Congreso y el Poder Judicial, se profundiza únicamente en las mencionadas pues del estudio se concluye que ambas tenderían a aumentar el potencial que de suyo ya tienen si se incorpora apertura en los procesosThis paper analyzes the relationship between the Chilean Congress and Judicial power, focusing on two institutions: the nomination process to appoint Supreme Court justices and the reports that the Supreme Court is constitutionally obligated to send to the Congress when specific types of bills are introduced. The appointment of Supreme Court candidates is studied from the Senate's incorporation in the process from 1997 until 2005. The author states that a more transparent process, including the publication of the candidate's backgrounds and public hearings, would increase the incentives to nominate the most qualified candidates. The paper also

  13. RELAÇÕES E PARALELOS ENTRE ROUSSEAU E A ECOLOGIA RADICAL CONTEMPORÂNEA

    Eduardo Cardoso Braga

    2013-12-01

    Full Text Available Verificou-se que, embora haja uma série de publicações contextualizando o pensamento de Rousseau no debate contemporâneo sobre a filosofia ambiental, a participação de seu pensamento é ainda diminuta. Relacionaram-se então alguns conceitos fundamentais da ecologia radical contemporânea com a filosofia rousseauniana. Constatou-se que ambos procedem a uma crítica radical do antropocentrismo, propondo, como alternativa, um ecocentrismo. Concentrou-se no conceito de “valor intrínseco” da natureza e suas implicações éticas no relacionamento entre homem e ambiente. No caso de Rousseau essa relação se desenvolve por meio de uma profunda análise das paixões amor-de-si e amor-próprio. Constatou-se que tanto a ecologia radical como Rousseau não acreditam na possibilidade de uma volta ao estado de natureza, porém é possível recuperar a experiência feliz da ligação com a totalidade da vida, que esse estado proporcionava aos homens. A recuperação somente pode ocorrer em outro registro, em meio à civilização e à tecnologia. Mostrou-se a importância da estratégia rousseauniana nessa questão ao propor a expansão do amor-próprio até uma dimensão de totalidade, recuperando dessa forma a possibilidade de uma vida feliz e significativa (boa-vida. Entretanto, tanto Rousseau como os partidários da ecologia radical consideram as dificuldades em se realizar tanto a experiência da totalidade como da vida ética na relação entre homem e natureza, dada as condições da contemporaneidade.

  14. Traducción automatizada de programas entre lenguajes de operaciones

    Diego Ordóñez Camacho

    2012-06-01

    Full Text Available Los lenguajes de operaciones se usan para programar, en procedimientos organizados, las instrucciones a ser ejecutadas por una máquina, para realizar distintos tipos de operaciones. Para poder importar procedimientos existentes realizados en un lenguaje de operaciones dado, en frameworks de programación específicos para el diseño de operaciones, es necesario contar con traductores entre el lenguaje en que ha sido programado el procedimiento, y el lenguaje interno utilizado por el framework de diseño. La construcción de estos traductores puede ser automatizada si se establece un mapeo entre producciones equivalentes de las gramáticas de los lenguajes fuente y destino. Las producciones se pueden considerar equivalentes cuando a pesar de tener una sintaxis diferente, tienen la misma intención semántica y pueden ser equiparadas con un árbol de sintaxis abstracta en común. Debido a ciertas diferencias sintácticas, en ocasiones este árbol sintáctico común no puede ser hallado directamente. Esto se vuelve posible, sin embargo, al realizar en primer lugar ciertas transformaciones a los programas. Este artículo presenta un acercamiento específico a la construcción de reglas de transformación para resolver estas diferencias.Abstract:Operations languages are used to program the procedures that instruct machinery to perform specific operations. To import procedures in a given operations language, into a dedicated tool for designing operations, language translators are needed to translate those procedures to the design tool's internal operations language. The construction of these translators can be automated by mapping equivalent productions in the grammar of source and target language. Productions are considered equivalent when, in spite of a differing syntax, they have the same intended semantics and can be matched to a same abstract syntax tree. For some corresponding productions, due to syntactic differences, such a common abstract

  15. El (los Sur buscando al Sur. Una construcción entre estereotipos y realidad.

    Mabel Franzone

    2010-11-01

    Full Text Available Todas las lecturas que podamos hacer del Sur, de sus propias representaciones, de aquellas vehiculizadas por el Norte, de sus creaciones, de sus reacciones, de su búsqueda constante de identidad, son lecturas de múltiples situaciones, que llaman a cruces insoslayables entre pueblos, entre distintas etnias, entre disciplinas, entre sentimientos que van desde el rechazo hasta la atracción casi magnética entre los dos hemisferios. Nuestra intención primera era la de reunir de manera aproximativa las problemáticas actuales de los Sur, ligadas a lo imaginario.

  16. Characterization of defects in Si and SiO2-Si using positrons

    Positron annihilation spectroscopy of overlayers, interfaces, and buried regions of semiconductors has seen a rapid growth in recent years. The characteristics of the annihilation gamma rays depend strongly on the local environment of the annihilation sites, and can be used to probe defect concentrations in a range inaccessible to conventional defect probes. Some of the recent success of the technique in examining low concentrations of point defects in technologically important Si-based structures is discussed

  17. Radiation Damage Effect on Si and SiC Detectors

    Silicon is an extraordinary semiconductor suited for the fabrication of radiation detector. Charge carrier lifetime and mobility are high, which is very important to make the radiation detector with low noise and good time behavior. Since the fabrication technology of the silicon was mature, one could easily make a radiation detector with a sophisticated structure. Therefore, silicon detector could be the best choice for the various application areas. The depletion layers of the reverse bias rectifying barriers are used to make the silicon radiation detector with low noise. The depletion layer could be made by a silicon surface barrier (SSB) structure or a PIN junction structure. SSB detector was made by depositing the metal electrode on the n or p type silicon wafer. The p-n junction could be made with the semiconductor fabrication process, and the X-ray or α particles could be measured with the detector. The radiation tolerance of the radiation detector is also very important for the application of the detector to the harsh environment. A study on the effect of the structure of the depletion layer on the radiation tolerance was rare in most of the previous works In the present work, the silicon detectors with two types were fabricated, and their operation characteristics are compared. The dependency of the radiation damage on the detector type was studied. We also fabricated SiC detector and the neutron and gamma irradiation effect on the detector was studied. The radiation tolerance of the detector was studied. One could see the change of the leakage current and the energy resolution in SSB detector, and the operating performance of the Si PIN detector was more stable than Si Schottky detector.

  18. La disciplina entre las disposiciones legales y los actores escolares

    Nancy Palacios Mena

    2013-01-01

    Full Text Available Este artículo presenta una descripción del funcionamiento de la disciplina escolar en una institución educativa de secundaria en Colombia. Tiene como objetivo explicar el origen del conflicto disciplinario, las situaciones que lo generan, la forma como la institución trata de lograr y mantener la disciplina, las explicaciones que cada uno de los actores da a las situaciones conflictivas y la manera como son vividas por ellos. El diseño metodológico de la investigación combinó una encuesta, entrevistas y el análisis de documentos de la institución educativa. El análisis de los datos se hace a la luz de planteamientos sociológicos que reconocen la enorme importancia que ejercen las estructuras sociales sobre la forma de pensar y actuar de los individuos, pero también resaltan la gran capacidad de los actores sociales para amoldarse a dichas estructuras y a través de sus ideas y acciones darle una dinámica propia al tipo de relaciones que establecen entre individuos en sus entornos de vida más inmediatos. Se pudo concluir que sobre la disciplina escolar no hay unidad de criterio entre los docentes, los directivos y los estudiantes, ni en su definición, ni en su importancia, ni en los medios para conseguirla; dichas diferencias producen tensiones y desacuerdos entre los miembros de la comunidad educativa.

  19. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  20. Aptitud combinatoria entre líneas de maíz resistentes a Mal de Río Cuarto

    Morata Mónica M.

    2003-01-01

    Full Text Available Se realizó un experimento dialélico entre nueve líneas de maíz (Zea mays (Método 4, modelo I de Griffing (1956 con el objeto de determinar Aptitud combinatoria general y específica (ACG y ACE para Resistencia a Mal de Río Cuarto (MRC. Los ambientes seleccionados fueron Pergamino, Junín, Ferré (región maicera VI y Sampacho y Holmberg (región maicera IV. La severidad de la enfermedad, evaluada a través del Grado Medio de Ataque (GMA, resultó nula en Pergamino y Junín, y de 0,14 en Ferré, con diferencias significativas entre tratamientos. En Holmberg fue de 0,59 y en Sampacho 1,57. El análisis de variancia para esta región detectó diferencias significativas entre ambientes y entre tratamientos, no detectándose interacción. El GMA promedio de los híbridos experimentales no se diferenció del promedio los testigos resistentes, si lo hizo de los testigos comerciales (más susceptibles. Veinticinco materiales experimentales no se diferenciaron del mejor de los testigos resistentes. La selección por pedigrí fue efectiva para mejorar este carácter. Los materiales experimentales en general demostraron poseer características que les darían competitividad en el mercado. Por su ACG, las líneas más resistentes a MRC fueron la 2526 y la 2378 (con efectos significativos y negativos: resistentes por los efectos de ACE, se destacaron los híbridos: 2378 x 2600, 2335 x 2600, LP561 x 2568-2 y 2526 x 2600. En Sampacho el 42% de la disminución en el rendimiento pudo atribuirse al MRC, en Holmberg el 8%.

  1. As condições sociais de produção das lembranças entre imigrantes ucranianos

    Paulo Renato Guérios

    2008-10-01

    Full Text Available O presente artigo propõe um enfoque para o estudo das relações entre "memória" e pertencimento social. A partir de uma crítica dos objetivos e dos instrumentos propostos nas obras de Maurice Halbwachs acerca da "memória coletiva", enceta uma discussão sobre as condições sociais que infletem a produção de lembranças entre pessoas ligadas a uma dada configuração social. São utilizadas como material empírico as lembranças produzidas por imigrantes camponeses de origem eslava - os "rutenos" ou "ucranianos" - a respeito de sua vinda ao Brasil no final do século XIX. O artigo inicia com um estudo crítico das idéias de Halbwachs sobre as relações entre "memória" e "sociedade"; após uma breve apresentação dos imigrantes ucranianos, explora seus relatos em torno de sua imigração para discutir os mecanismos sociais que incidem em suas lembranças em sentidos convergentes ou divergentes entre si; e conclui-se com o exame de algumas implicações da análise empreendida.This article seeks to put into focus the study of the relationship between "memory" and social belonging. Beginning with a critique of the objectives and tools advanced in Maurice Halbwachs's writings on "collective memory", the article embarks on a discussion of the social conditions that inflect upon the production of memories among people linked to a given social configuration. The empirical bases for the analysis are the recollections produced by peasant immigrants of Slavic origin - the "Rusyns" or "Ukrainians" - concerning their journey to Brazil in the end of the nineteenth century. The article starts with a critical study of Halbwachs's ideas on the relationship between "memory" and "society", and, after a brief presentation of the Ukrainian immigrants, explores the stories concerning their migrations in order to discuss the social mechanisms that impress upon their recollections meanings that both converge or diverge amongst themselves. It concludes by an

  2. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  3. Entre ‘terminator’ y ‘frankencell

    García Olmedo, Francisco

    1999-01-01

    Una sola palabra bien buscada puede ser más eficaz que cien argumentos cuando se trata de desacreditar cualquier idea o iniciativa, del mismo modo que las caricaturas guiñolescas están haciendo estragos entre nuestros personajes públicos. Así es el caso del apelativo "terminator", que ha sido elegido con indudable ingenio por los enemigos de una particular receta fitogenética cuyos autores son científicos del Ministerio de Agricultura de Estados Unidos y de la empresa Delta & Pine Land Compan...

  4. Sobre la relación de preferencias entre argumentos

    Cecchi, Laura; Simari, Guillermo Ricardo

    2002-01-01

    Los diferentes modelos de sistemas argumentativos son formalismos de representación y razonamiento no monotónico que permiten caracterizar una de los principales habilidades de la inteligencia humana: la argumentación. Al definir un framework argumentativo se exige un criterio de preferencia entre argumentos, sin restringir la relación que formaliza su comportamiento. Esto motivó el estudio dicha relación, desde el punto de vista matemático, a fin de caracterizarla. El propósito de este...

  5. Martyre et mort volontaire en Europe. : Entre religion et politique

    Albert, Jean-Pierre

    2007-01-01

    On tente ici de définir les ressorts à la fois religieux et politiques de l'acceptation altruiste de mourir pour une communauté. Les liens entre un tel devoir et une société holiste sont affirmés à partir d'une relecture de textes de Hobbes et de Durkheim, qui propose dans son célèbre ouvrage une définition souvent oubliée du « suicide altruiste ».

  6. Comportamientos violentos entre pares: estrategias de prevención

    Salas, Marta A.; Carreras, Julia A.; Casacci, María Elena; Garcia, Alicia; Hogas, Alejandro; Medina, Daniel

    2007-01-01

    En este trabajo se articulan dos proyectos de investigaciones llevados a cabo el primero investigó la incidencia en la subjetividad de la manera en que el adulto naturaliza las múltiples y variadas formas de castigo en la familia; el segundo y actual, investiga las manifestaciones de los comportamientos violentos en los niños, y las representaciones sociales de la violencia Objetivos: Identificar a los fines de su prevención las principales manifestaciones e interacciones violentas entre pare...

  7. Entre el desarrollo y el ambiente: incertidumbres de los agrocombustibles

    León Sicard, Tomás Enrique

    2008-01-01

    El artículo plantea una discusión sobre la manera en que la dimensión ambiental puede ser concebida en relación con el actual concepto de desarrollo, a partir de una visión que entiende lo ambiental como relaciones complejas entre los ecosistemas y las culturas humanas y a partir de este punto, examina el modelo agrario dominante en Colombia versus los modelos de agricultura alternativa y la aparición de los biocombustibles, como una consecuencia ineludible del modelo domi...

  8. Relaciones entre trastornos del lenguaje y competencia socioemocional

    Colomer Diago, Carla; Roselló Miranda, Belén; Baixauli-Fortea, Inmaculada

    2015-01-01

    Introducción. Existe una comorbilidad elevada entre los trastornos del lenguaje y los problemas conductuales, emocionales y sociales. Objetivo. Revisar la bibliografía existente sobre las dificultades sociales y emocionales de los niños con trastorno específico del lenguaje desde una perspectiva evolutiva. Desarrollo. En la infancia temprana, los resultados acerca de este tipo de dificultades en niños con un retraso del lenguaje no son concluyentes. Sin embargo, desde el período d...

  9. Consumo de bebidas alcohólicas entre deficientes visuales.

    Freitas da Silva, G.R.; De Freitas Macêdo, K.N.

    2005-01-01

    Se sabe que el alcohol es una de las drogas más conocidas y usadas, siendo quizá la de mayor popularidad junto al tabaco, a pesar de muchas veces no ser reconocida como tal, por convertirse en un elemento de fácil obtención y estar asociado a la vida cultural y social de las personas. Se trazó un perfil entre deficientes visuales que consumen bebidas alcohólicas. Basándose en una investigación anterior en la se realizaron Consultas de Enfermería a 22 deficientes visuales e...

  10. Empresas excelentes entre las certificadas en las normas ISO 9000

    Climent Serrano, Salvador

    2005-01-01

    En este trabajo se realiza un estudio entre las empresas certificadas en la norma ISO 9000 de la Comunidad Valenciana mediante una encuesta, con el objetivo de diferenciar los resultados sobre incremento de competitividad por la certificación en las normas ISO 9000, dependiendo de la involucración de las empresas en los sistemas de gestión de la calidad total, así como averiguar que factores inciden para que las empresas certificadas se impliquen en mayor medida en estos sistemas

  11. Oniromancia y perspectiva entre los ette del norte de colombia

    Juan Camilo Niño Vargas

    2009-01-01

    En algunas sociedades la interpretación onírica se considera una labor lógi- ca y significativa. La explicación de este hecho se encuentra en la forma en que el mundo ha sido construido socialmente. El presente artículo se interesa por la particular articulación de estas ideas entre los ette, una sociedad indígena del norte de Colombia que le ha otorgado al fenóme- no del sueño un lugar central dentro de la vida diaria. Para este efecto, ...

  12. Relación entre diabetes mellitus y enfermedad periodontal

    A.B. Navarro Sánchez

    2002-04-01

    Full Text Available La asociación entre diabetes mellitus y la enfermedad periodontal ha sido motivo de estudio durante mucho tiempo. Son varias las hipótesis que se barajan a la hora de explicar dicha relación. El propósito de este artículo es revisar los estudios publicados en la literatura periodontal hasta la fecha.The association between diabetes mellitus und Periodontal. Disease have been studied for a long time. There are several hypothesis which have tried to explain this relation. The purpose of this paper is to review the Periodontal literature up to day.

  13. Discapacidad y trabajo. El otro entre discursos y hechos

    Míguez, María Noel; Gómez, Ana Paula; Pinato, Cristian

    2015-01-01

    El objetivo de la presente investigación apunta a deconstruir los conceptos de normalidad e igualdad en el entramado de contingencias que se materializan en la temática de la discapacidad con relación al trabajo como categoría ontológica que media al ser. Así, se intenta dar cuenta de la ideología de la normalidad y los discursos de igualdad en la relación discapacidad-trabajo a través de un análisis correlativo entre Uruguay y Francia.

  14. Risco ocupacional de adquirir tuberculose entre trabalhadores de enfermagem hospitalar

    2001-01-01

    Nos hospitais, os indivíduos tuberculosos são atendidos por vários profissionais e dentre eles os trabalhadores de enfermagem. Esses trabalhadores estão sujeitos a riscos de infecção tuberculosa. O estudo objetivou: levantar o número de trabalhadores de enfermagem do hospital que adquiriram tuberculose, e as características gerais em um período pré determinado; levantar a morbidade dessa doença e discutir o risco ocupacional entre estes trabalhadores. Em um ano os trabalhadores apresentaram r...

  15. Relaciones entre autoestima y estresores percibidos en estudiantes universitarios

    Cabanach, Ramón G.; Antonio Souto Gestal; Carlos Freire Rodríguez; María del Mar Ferradás Canedo

    2014-01-01

    Siguiendo la línea de los trabajos que inciden en el papel de los recursos personales como factores de protección frente al estrés, la presente investigación pretende analizar la relación entre la autoestima y la percepción de estresores académicos en el contexto universitario. En concreto, analizamos en qué medida los niveles de autoestima (alto, medio y bajo) influyen diferencialmente en el grado en que el estudiante valora como amenazantes diversas circunstancias propias del día a día acad...

  16. Psiconeuroinmunologia: relaciones entre factores psicologicos e inmunitarios en humanos

    Vera Villarroel, Pablo E.; Gualberto Buela Casal

    1999-01-01

    La Psiconeuroinmunología (PNI) es un campo que estudia las relaciones bidireccionales entre la conducta, el cerebro y el sistema inmune. Desde los estudios iniciales de inmunodepresión e inmunoactivación condicionada realizadaen animales se han llevado acabo una gran cantidad de estudios en humanos, intentando verificar hasta qué punto el sistema inmune está sujeto a las influencias psicosociales. El presente artículo revisa algunos avances en esta área centrándose exclusiva...

  17. La controversia entre homosexualidad y familia : el caso cubano

    ROBLEDO DÍAZ, LUIS

    2004-01-01

    El presente artículo constituye un resumen de la tesis Homosexualidad y familia: acoso y simetrías que el autor presentara para obtener el título de máster en Sociología por la Universidad Autónoma de Barcelona y la Universidad de La Habana. En la misma nos propusimos caracterizar algunos aspectos de la relación entre homosexualidad y familia en el contexto cubano. Para ello, nos centramos en describir los aspectos relativos a la «vida gay» en Ciudad de La Habana y en determinar el vínculo es...

  18. Relações comerciais entre Brasil e Argentina

    Malheiro Da Silva, Felipe

    2014-01-01

    Las relaciones políticas y comerciales entre Brasil y Argentina son muy importantes para ambos países. Brasil es el principal socio comercial de Argentina y principal destino de las exportaciones y las importaciones. A partir de este escenario es fundamental examinar la relación de los dos países, analizando el punto de vista geopolítico, económico y filosófico. Además realizar un análisis de los bloques económicos ABC, MERCOSUR y BRICS, siendo de gran inportancia argumentar acerca de las raz...

  19. Entre Dios y los hombres: la sexualidad femenina

    Saavedra Ballesteros, Blanca Lida

    2006-01-01

    Entre dios y los hombres: la sexualidad femenina, nos aproximará a la realidad discursiva que sobre la sexualidad femenina tienen las mujeres católicas - perfil obtenido por un estudio de casos basado en grupos de oración - . Se hará relevante, entonces, la influencia que ejerce en ellas el discurso de la Iglesia Católica respecto al tema, a la vez que se notarán, igualmente, las filtraciones que, poco a poco, provocan los discursos de las feministas y teólogas feministas latinoamericanas. As...

  20. Fabrication and characterization of Ti3SiC2–SiC nanocomposite by in situ reaction synthesis of TiC/Si/Al powders

    Baoyan Liang; Mingzhi Wang; Xiaopu Li; Yunchao Mu

    2011-12-01

    The microstructure and mechanical properties of Ti3SiC2–SiC nanocomposite fabricated by in situ hot pressing (HP) synthesis process were studied. The results show that dense Ti3SiC2–SiC composite contained minor TiSi2 obtained by hot sintering at 1350°C for 1 h. The average grain size of Ti3SiC2 was 4 m in length, and the size of SiC grains is about 100 nm. With its fine microstructure, the Ti3SiC2–SiC nanocomposite shows good mechanical properties.

  1. Si3N4/SiC nanocomposite powder from a preceramic polymeric network based on poly(methylsilane as the SiC precursor

    Gozzi Maurício F.

    2001-01-01

    Full Text Available Si3N4/SiC nanocomposite powders were obtained from a preceramic polymeric network based on poly(methylsilane as the in situ quasi-stoichiometric SiC source. These powders were constituted of nanosized SiC particles homogeneously distributed in the Si3N4 particulate matrix. beta-SiC whiskers were grown at 1400 °C in the pores of the matrix. At 1600 °C, the alpha -> beta Si3N4 phase transition took place, but no elemental silicon from Si3N4 decomposition was detected, evidencing the protective effect of the SiC phase.

  2. Study of indentation induced cracks in MoSi2-reaction bonded SiC ceramics

    O P Chakrabarti; P K Das; S Mondal

    2001-04-01

    MoSi2–RBSC composite samples were prepared by infiltration of Si–2 at.% Mo melt into a preform of commercial SiC and petroleum coke powder. The infiltrated sample had a density > 92% of the theoretical density (TD) and microstructurally contained SiC, MoSi2, residual Si and unreacted C. The material was tested for indentation fracture toughness at room temperature with a Vicker’s indenter and KIC was found to be 4.42 MPa√m which is around 39% higher than the conventional RBSC material. Enhancement in indentation fracture toughness is explained in terms of bowing of propagating cracks through MoSi2/SiC interface which is under high thermal stress arising from the thermal expansion mismatch between MoSi2 and SiC.

  3. Propagation of misfit dislocations from buffer/Si interface into Si

    Liliental-Weber, Zuzanna; Maltez, Rogerio Luis; Morkoc, Hadis; Xie, Jinqiao

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  4. Surface modifying of SiC particles and performance analysis of SiCp/Cu composites

    Ming, Hu; Yunlong, Zhang; Lili, Tang; Lin, Shan; Jing, Gao; Peiling, Ding

    2015-03-01

    In this study, the electroless copper plating method was applied to deposit a Cu coating on SiCp in order to improve interface bonding performance. The SiCp surface morphology with uncoated and coated copper was investigated. The SiCp/Cu composite was fabricated by the hot-pressed sintering technology. SiC particles with various contents were used as reinforcement. The results showed that the distribution of reinforced particle with electroless plating copper coating was uniform in the copper matrix. The SiCp content played had an important role on thermal expansion coefficient and wear properties behaviors of the SiCp/Cu composites. The wear resistance capacity and thermal expansion coefficient of the composites decreased with increasing amount of SiC. Compared with the pure Cu matrix, the obtained SiCp/Cu composites had better capacity of the wear resistance. The SiCp/Cu composites increased when compared with the pure Cu material.

  5. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  6. Microwave Annealing for NiSiGe Schottky Junction on SiGe P-Channel

    Yu-Hsien Lin

    2015-11-01

    Full Text Available In this paper, we demonstrated the shallow NiSiGe Schottky junction on the SiGe P-channel by using low-temperature microwave annealing. The NiSiGe/n-Si Schottky junction was formed for the Si-capped/SiGe multi-layer structure on an n-Si substrate (Si/Si0.57Ge0.43/Si through microwave annealing (MWA ranging from 200 to 470 °C for 150 s in N2 ambient. MWA has the advantage of being diffusion-less during activation, having a low-temperature process, have a lower junction leakage current, and having low sheet resistance (Rs and contact resistivity. In our study, a 20 nm NiSiGe Schottky junction was formed by TEM and XRD analysis at MWA 390 °C. The NiSiGe/n-Si Schottky junction exhibits the highest forward/reverse current (ION/IOFF ratio of ~3 × 105. The low temperature MWA is a very promising thermal process technology for NiSiGe Schottky junction manufacturing.

  7. On the peritectoid Ti3Si formation in Ti-Si alloys

    Ti-13.5Si and Ti-25Si (at.%) alloys have been arc-melted from high-purity raw materials, using a water-cooled copper hearth, a non-consumable tungsten electrode, and under an Ar atmosphere gettered by titanium. The cast ingots were then heat-treated for 90 h at 1000 and 1100 deg. C in an inert atmosphere, and both the as-cast and the heat-treated alloys were characterized using scanning electron microscopy and an energy dispersive microanalysis system. The as-cast Ti-13.5Si alloy presented a eutectic microstructure composed of the TiSS and Ti5Si3 phases, while the microstructure of the as-cast Ti-25Si alloy showed the presence of large primary precipitates of Ti5Si3 in a eutectic matrix of TiSS and Ti5Si3. Subsequent heat treatment at 1100 deg. C produced no significant microstructural modifications in the Ti-25Si alloy, and it is suggested that the presence of the large primary precipitates of Ti5Si3 contributed to a reduction in the kinetics of Ti3Si formation. In the Ti-13.5Si alloys, the formation of Ti3Si was not observed after heat treatment at 1000 deg. C, but a large amount of Ti3Si was found after heat treatment at 1100 deg. C, confirming its existence in Ti-Si alloys containing low interstitial contents

  8. Si self-diffusivity using isotopically pure 30Si epitaxial layers

    In order to understand the properties of point defects in Si, it is important to clarify temperature dependence of Si intrinsic self-diffusion coefficient over a wide temperature range. In this work, we used highly isotopically enriched 30Si epi-layers as a diffusion source to bulk and epi-layers Si and evaluated self-diffusion 30Si epi-layers were grown on each CZ-Si substrate and non-doped epi-layer grown on CZ-Si substrate using low pressure CVD with 30SiH4. Diffusion was performed in resistance furnaces under pure Ar (99.9%) atmosphere at temperature between 867 and 1300 deg. C. After annealing, the concentrations of the respective Si isotopes were measured with SIMS. Diffusion coefficients of 30Si (called Si self-diffusivity, D SD) were determined using numerical fitting process with 30Si SIMS profiles. We found no major differences in self-diffusivity between in bulk Si and epi-layers Si. It was shown that within 867-1300 deg. C range, D SD can be described by an Arrhenius equation with one single activation enthalpy, D SD = 14 exp (-4.37 eV/kT). The present result is in good agreement with that of Bracht et al

  9. Relação entre o craving por tabaco e o craving por crack em pacientes internados para desintoxicação

    Taís Cardoso de Zeni

    2011-01-01

    Full Text Available OBJETIVO: Verificar se há relação entre aumento do craving por crack e aumento do craving por tabaco em pacientes internados para desintoxicação. MÉTODO: Ensaio clínico tipo quase-experimental de análise quantitativa. Amostra composta por 32 homens dependentes de cocaína (crack e tabaco, em duas a três semanas de abstinência. Realizou-se intervenção em grupo, no qual, inicialmente, foram aplicados: CCQB (Cocaine Craving Questionnaire-Brief , QSUB (Questionnaire of Smoking Urges-Brief e BAI (Inventário Beck de Ansiedade. Em seguida, foram aplicadas imagens relacionadas ao crack e reaplicados CCQB, QSUB e BAI. Após, foi realizada entrevista individual em que se aplicaram FSD (Ficha com Dados Sociodemográficos e FTND (Fagerström Test for Nicotine Dependence. RESULTADOS: A partir da exposição de imagens relativas ao crack, houve aumento significativo do craving por crack, do craving por tabaco e dos sintomas de ansiedade, estando essas medidas correlacionadas positivamente entre si. CONCLUSÃO: Os resultados indicam uma associação significativa entre craving por crack e craving por tabaco, sugerindo que a abstinência de tabaco pode ajudar na eficácia do tratamento para dependência de crack.

  10. Relación entre la potencia muscular de extremidades inferiores y tronco con la velocidad de salida de la bola en el swing de drive en golf

    Lorena Torres Ronda

    2010-09-01

    Full Text Available A pesar del interés emergente en el acondicionamiento físico en el golf, se han llevado a cabo pocos estudios para valorar la relación entre la potencia mecánica y el rendimiento en golf. El objetivo de este estudio fue valorar si existía una correlación entre la velocidad de salida de la bola del swing de drive y la potencia muscular de extremidades inferiores y tronco, en un grupo de 8 golfistas (16,8 ± 1,4 años; 2,2 ± 1,8 Handicap; 63,1 ± 6,4 kg.; 172,7 ± 7,5 cm. El test incluyó mediciones de la velocidad de salida de la bola y tests de potencia mecánica (prensa de piernas horizontal, press de banca y rotaciones de tronco. Los resultados de este estudio indican que existe una correlación significativa entre la velocidad de salida de la bola y la potencia piernas (prensa de piernas horizontal: r2=,933; p=,000 y del tronco (press de banca: r2 = 0,66; p = ,014. La prensa de piernas se mostró como el predictor más representativo para la velocidad de salida de la bola (r2 = 0,934; p = ,000.

  11. Annealing induced defects in SiC, SiO{sub x} single layers, and SiC/SiO{sub x} hetero-superlattices

    Ding, Kaining; Aeberhard, Urs; Beyer, Wolfhard; Astakhov, Oleksandr; Koehler, Florian; Finger, Friedhelm; Carius, Reinhard; Rau, Uwe [IEK5-Photovoltaik, Forschungszentrum Juelich, Leo-Brandt-Strasse, 52425 Juelich (Germany); Breuer, Uwe [Central Division of Analytical Chemistry (ZCH), Forschungszentrum Juelich, Leo-Brandt-Strasse, 52425 Juelich (Germany)

    2012-10-15

    SiC/SiO{sub x} hetero-superlattices as well as single layers of SiC and SiO{sub x} were fabricated and annealed at various annealing temperatures to investigate the evolution of annealing induced defects in these materials. We show that in SiC and SiO{sub x} materials and in SiC/SiO{sub x} multilayer system, crystallization, atomic diffusion, structural reconstruction, and hydrogen effusion take place upon annealing with different characteristic temperature dependences. The dependence of the spin densities on annealing temperature is explained as an overlap of the temperature dependence of the creation of additional dangling bonds due to hydrogen effusion and of the healing of dangling bonds due to element motion during the structural reconstruction. The stronger increase of spin density upon annealing in SiC as compared to SiO{sub 1.2} is ascribed to the effusion of a higher amount of hydrogen and the less efficient atomic diffusion up to the annealing temperature of 1050 C. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Solution plasma synthesis of Si nanoparticles

    Saito, Genki; Sakaguchi, Norihito

    2015-06-01

    Silicon nanoparticles (Si-NPs) were directly synthesized from a Si bar electrode via a solution plasma. In order to produce smaller Si-NPs, the effects of different electrolytes and applied voltages on the product were investigated in the experiments detailed in this paper. The results demonstrated that the use of an acidic solution of 0.1 M HCl or HNO3 produced Si-NPs without SiO2 formation. According to the transmission electron microscopy and electron energy-loss spectroscopy, the obtained Si-NPs contained both amorphous and polycrystalline Si particles, among which the smaller Si-NPs tended to be amorphous. When an alkaline solution of K2CO3 was used instead, amorphous SiO2 particles were synthesized owing to the corrosion of Si in the high-temperature environment. The pH values of KCl and KNO3 increased during electrolysis, and the products were partially oxidized in the alkaline solutions. The particle size increased with an increasing applied voltage because the excitation temperature of the plasma increased.

  13. SI PC104 Performance Test Report

    Montelongo, S

    2005-12-16

    The Spectral Instruments (SI) PC104 systems associated with the SI-1000 CCD camera exhibited intermittent power problems during setup, test and operations which called for further evaluation and testing. The SI PC104 System is the interface between the SI-1000 CCD camera and its associated Diagnostic Controller (DC). As such, the SI PC104 must be a reliable, robust system capable of providing consistent performance in various configurations and operating conditions. This SI PC104 system consists of a stackable set of modules designed to meet the PC104+ Industry Standard. The SI PC104 System consists of a CPU module, SI Camera card, Media converter card, Video card and a I/O module. The root cause of power problems was identified as failing solder joints at the LEMO power connector attached to the SI Camera Card. The recommended solution was to provide power to the PC104 system via a PC104+ power supply module configured into the PC104 stack instead of thru the LEMO power connector. Test plans (2) were developed to test SI PC104 performance and identify any outstanding issues noted during extended operations. Test Plan 1 included performance and image acquisition tests. Test Plan 2 verified performance after implementing recommendations. Test Plan 2 also included verifying integrity of system files and driver installation after bootup. Each test plan was implemented to fully test against each set of problems noted. Test Plan presentations and Test Plan results are attached as appendices. Anticipated test results will show successful operation and reliable performance of the SI PC104 system receiving its power via a PC104 power supply module. A SI PC104 Usage Recommendation Memo will be sent out to the SI PC104 User Community. Recommendation memo(s) are attached as appendices.

  14. Thoughts on a changing SI

    Cabiati, Franco; Bich, Walter

    2009-10-01

    The trend towards an International System of Units (SI) based on fundamental constants has been confirmed and recent actions could result in the redefinition of the four units still necessary to cover all the quantities of interest for physics and chemistry. In this paper some issues whose solution is becoming critical with the approach of the General Conference on Weights and Measures (CGPM) of 2011 are discussed. The traditional kinds of definition and the new proposals are considered on the basis of their mathematical expressions and the advantageous features of the most advanced proposal are pointed out. The problem of choosing the set of fundamental constants to be adopted as reference quantities for the SI units is addressed and a general rule for verifying that the set is sufficient and non-redundant is pointed out in the form of a linear system giving also expressions of all the units as functions of the reference constants. A partial application to the most important units and different sets of constants offers some comparative criteria and shows the advantages of a set including both h and me. A general condition to be fulfilled by an experiment in order to realize an SI unit is given and a procedure suitable to optimize the availability of the best relization on a global basis is outlined. Finally, the dissemination process is analysed to show that the implied comparisons of standards at any level are not affected by the realization uncertainty, so that the process can be continued with the same standards, independently of any change in the basic reference quantities of the unit system.

  15. Hydrogen Passivation Effect on Enhanced Luminescence from Nanocrystalline Si/SiO2 Multilayers

    XIA Zheng-Yue; HAN Pei-Gao; XU Jun; CHEN De-Yuan; WEI De-Yuan; MA Zhong-Yuan; CHEN Kun-Ji; XU Ling; HUANG Xin-Fan

    2007-01-01

    Nanocrystalline Si/SiO2 multilayers are prepared by thermally annealing amorphous Si/SiO2 stacked structures.The photoluminescence intensity is obviously enhanced after hydrogen passivation at various temperatures. It is suggested that the hydrogen trapping and detrapping processes at different temperatures strongly influence the passivation effect. Direct experimental evidence is given by electron spin resonance spectra that hydrogen effectively reduces the nonradiative defect states existing in the Si nanocrystas/SiO2 system which enhances the radiative recombination probability. The luminescence characteristic shows its stability after hydrogen passivation even after aging eight months.

  16. Excitation wavelength dependent photoluminescence in structurally non-uniform Si/SiGe-island heteroepitxial multilayers

    Modi, N.; Tsybeskov, L. [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Lockwood, D. J.; Wu, X.; Baribeau, J.-M. [Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2012-06-01

    In nanometer-size Si/SiGe-island heteroepitxial multilayers grown on Si(001), low temperature photoluminescence spectra are observed that strongly depend on the excitation wavelength and show a strong correlation with structural properties revealed by transmission electron microscopy. These experimental results can be explained by assuming that the optically created carriers are strongly localized at Si/SiGe island heterointerfaces. We show that electron-hole pairs are generated and recombine within spatial regions mainly defined by the photoexcitation penetration depth, and that the estimated exciton diffusion length is notably short and comparable with the SiGe-island average size.

  17. Metamorfoses nas vanguardas: entre o homem e o animal

    Kelvin Falcão Klein

    2011-08-01

    Full Text Available Este trabalho investiga a relação que se estabeleceu entre o homem e o animal no pensamento das vanguardas européias no início do século XX, principalmente o surrealismo, além de considerar uma parte de suas bases históricas e de suas sobrevivências na contemporaneidade. Partindo do caso de Édipo e da Esfinge, e das diferentes percepções críticas que gerou (desde Freud até Jacques Lacan e Giorgio Agamben, este trabalho reflete sobre as estratégias de afirmação do discurso da razão e da verdade na cultura ocidental, alcançando, com isso, o projeto de revistas de vanguarda como Acéphale e Minotaure. A categoria de metamorfose, na articulação com outros casos, é utilizada para considerar as implicações críticas do questionamento das fronteiras entre o homem e sua animalidade.

  18. Bogotá: entre la identidad y el marketing urbano

    Duque Franco Isabel

    2011-07-01

    Full Text Available Durante los últimos años, en el marco de la competitividad entre ciudades, el marketing urbano se ha convertido en un instrumento adicional de la gestión y la planificación estratégicas para responder a la necesidad de atraer inversiones, empresas y turistas. En el presente artículo se abordan, desde una perspectiva crítica, la naturaleza, los tipos y los alcances del marketing urbano. En la parte empírica, se analizan las campañas de promoción interna y externa que han llevado a cabo las diferentes administraciones de Bogotá en los últimos quince años que evidencian cierto grado de continuidad y secuencia lógica en tanto en una primera instancia le apuestan a la promoción y consolidación de una imagen de ciudad interna más o menos compartida por entidades y ciudadanos, para luego proyectarse hacia fuera, asumiendo directamente los requerimientos de la competitividad entre ciudades.

  19. Relación entre Cultura y Valores Organizacionales

    Carlos Roberto Rodríguez Castellanos

    2013-01-01

    Full Text Available Las organizaciones son sistemas activos y como cualquier otro sistema, funcionan mejor cuando variables como la cultura y valores organizacionales obran en una misma dirección. Dichas variables son elementales para una organización que pretende que sus trabajadores estén cohesionados, compartan sus objetivos, estén motivados, coordinados, sean leales y más eficientes. Esta investigación tiene como finalidad identificar la cultura y valores organizacionales presentes en los trabajadores de nivel operativo de una empresa de tamaño grande, además de evaluar la relación existente entre estas dos variables. Se aplicó una encuesta en una muestra de 171 trabajadores, los resultados revelan que la cultura organizacional que predomina es la de mercado, mientras que el valor organizacional que destaca en los empleados es el de auto trascendencia. A través de la prueba de hipótesis de Ji cuadrada, se encontró una relación significativa entre la cultura y los valores organizacionales de la empresa. Esta correspondencia representa una oportunidad para conseguir un mejor desarrollo y desempeño organizacional.

  20. A LIBERDADE EM SARTRE: UNIDADE ENTRE PROJETO E ENGAJAMENTO

    Josiane Fátima Wambier

    2003-01-01

    Full Text Available O objetivo deste trabalho é refletir a liberdade em Sartre, tendo como base os textos: O existencialismo é um humanismo (1945 e Questão de método, a célebre introdução de Crítica da razão dialética (1960. A liberdade em Sartre é um tema filosófico e literário. No início do processo de sua trajetória intelectual, ela é encerrada dentro do cogito cartesiano: “penso, logo existo”. Apesar de ser concebida como uma pura subjetividade, ela também é entendida como projeto que se realiza na ação através do engajamento do homem no mundo. Posteriormente, ela é remetida para o plano histórico e relacionada com a necessidade no interior de uma tensão dialética entre objetividade e subjetividade. Mesmo nesta fase, o núcleo central do conceito sartreano de liberdade é conservado: a unidade entre projeto e engajamento.

  1. Desarrollo convergente municipal entre estados contiguos a Nayarit y Sinaloa

    Eduardo Meza-Ramos

    2010-01-01

    Full Text Available El análisis del crecimiento económico registra disparidades sectoriales que se manifiestan en el interior de los países, entre las áreas urbanas y las rurales; entre las regiones prósperas y las rezagadas. En México la política de liberalización comercial no se ha visto reflejada de manera generalizada en la riqueza de la población. Se evaluó la hipótesis de convergencia en el ámbito municipal de los estados de Chihuahua, Durango, Jalisco, Nayarit, Sinaloa, Sonora y Zacatecas; por los datos considerados en el estudio se puede argumentar la existencia de convergencia ¿ y ¿, pues en promedio, la desviación estándar en el año 1989 fue de 1.73 y disminuyó a 1.31 en 2006. La convergencia ¿ describe una relación negativa con un valor absoluto de su estadístico mayor a 2; con 95% de confianza. Cabe señalar que se cuenta con políticas sociales y sectoriales pero se carece de políticas públicas que promuevan el desarrollo regional.

  2. Prazer e sofrimento entre os trabalhadores de Call Center

    Carolina Scolari

    2009-12-01

    Full Text Available Os conceitos de Taylor foram fundamentais para o desenvolvimento industrial no século XX. Ainda hoje, seus ensinamentos estão presentes em diversos ramos da economia, inclusive, no setor de call center. Call center é uma estrutura que visa ao atendimento de clientes com a utilização de um terminal de computador e de um aparelho telefônico. Esse setor sofreu grande expansão e, em 2006, foi responsável pela geração de 60 mil empregos diretos, tornando-se uma forma de contato e negócios atrativa para empresas do ramo público e privado. O objetivo deste artigo foi analisar as vivências de prazer e sofrimento no trabalho entre os operadores de call centers. Foi realizada uma pesquisa qualitativa, estratégia de estudo de caso e método de análise dos dados, análise de conteúdo. Como resultados, foram elaboradas algumas categorias finais, entre elas as mediações no trabalho, analisada no presente artigo sob o referencial teórico da psicodinâmica do trabalho.

  3. Lócus digital: um lugar entre tantos outros

    Fabio B. Josgrilberg

    2012-01-01

    Full Text Available El actual periodo técnico articula relaciones sociales y objetos técnicos con una racionalidad que le es propia. Con base en las ideas de Milton Santos, Michel de Certeau y Maurice Merleau-Ponty, se pretende reflexionar acerca de la relación dialéctica entre las determinaciones técnicas y las prácticas cotidianas de los sujetos. Destacamos el concepto de locus digital como un lugar organizado por estrategias que movilizan sistemas digitales de información y comunicación, sostenidos por una infraestructura peculiar de red distribuida. En el locus digital, los ciudadanos y ciudadanas están sometidos a presiones diversas, sino también reinventan la vida, crean espacios. La reflexión sobre la relación dialéctica entre locus digital y la reinvención de espacios busca evitar tanto el relativismo en la comprensión de las prácticas cuotidianas como el determinismo tecnológico.

  4. Interfacial microstructure of NiSi x/HfO2/SiO x/Si gate stacks

    Integration of NiSi x based fully silicided metal gates with HfO2 high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi x film. Ni content varies near the NiSi/HfOx interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi x/HfO2 interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi x/HfO x was found higher than that of poly-Si/HfO2, likely due to compositional non-uniformity of NiSi x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed

  5. Near K-edge linear attenuation coefficients for Si, SiO2 and Si3N4

    We present tabulated near K-edge linear attenuation coefficients for a range of materials commonly used in MOS construction; namely, crystalline silicon (Si-c), amorphous silicon (Si-a), amorphous silicon dioxide (SiO2-a) and amorphous silicon nitride (Si3N4-a). The coefficients were derived from total photocurrent measurements of X-ray absorption fine structure (XAFS) obtained at the Daresbury Synchrotron Radiation Source and show considerable near-edge structure when compared to curves generated from standard atomic data tables

  6. Phase separation of thin SiO layers in amorphous SiO/SiO2 superlattices during annealing

    The preparation of ordered and arranged Si quantum dots using a SiO/SiO2 superlattice approach is presented. The different processes of phase separation and crystallization are studied in detail by infrared (IR) absorption and photoluminescence (PL) spectroscopy for different annealing temperatures from 300 to 1100 deg. C. IR spectra show a continuous shift of the Si-O-Si asymmetric stretching mode to higher energies with increasing annealing temperature, which is a sign of phase separation to Si and SiO2. Three PL bands are distinguished and correspond to the three processes of phase separation. A band centred at 2.2 eV is present in as-prepared samples and vanishes for annealing above 800 deg. C which is clearly correlated with defects. The second band shifting from 1.7 to 1.4 eV is detected for annealing temperatures between 300 and 900 deg. C. A strong red luminescence due to quantum confinement is observed for annealing above 900 deg. C. Our results indicate that the different and seemingly contradictory PL observations in the literature could originate from different states of network reorganization during the phase separation and crystallization processes. The origins of the different IR and PL bands are discussed in comparison with those of bulk crystalline SiO and SiO2

  7. El comercio bilateral de cosméticos entre Argentina y Brasil en el MERCOSUR entre 2009 y 2013

    Odorizzi, Leila Aparecida

    2016-01-01

    Esta investigación tiene como objetivo general analizar el sector industrial de cosméticos entre Brasil y Argentina. Para ello, se valió de metodología cuantitativa y análisis descriptivo, generando gráficos, cuadros y tablas capaces de representar los datos de forma dinámica. Las consideraciones finales responden a los objetivos e hipótesis de este estudio, así como a la pregunta de esta investigación, señalando que el crecimiento del sector de cosméticos alcanza un excelente rendimiento com...

  8. Interactions entre virus ou entre virus et leurs satellites chez un hote commun. II. - Interferences positives : synergie, complementation, assistance

    MARCHOUX, Georges

    1988-01-01

    Deux ou plusieurs virus, apparentés ou non, peuvent se multiplier ensemble dans une même plante et également dans une même cellule. Les interactions entre virus qui en résultent peuvent s’exprimer sur les formes variées allant de l’antagonisme (MARCHOUX 1987) à la synergie. Dans les cas de synergie, les symptômes, la vitesse de multiplication et/ou la distribution d’un virus sont souvent augmentés en présence d’un autre virus. Des interactions structurales nucléoprotéiques, telles que mas...

  9. Relación entre el consumo de drogas y maltrato infantil entre estudiantes universitarios de la universidad en Colombia

    Monica Rosaura Garcia Baquero; Robert Mann; Hayley Hamilton; Pat Erickson; Bruna Brands; Norman Giesbrecht; Maria da Glória Miotto Wright; Francisco Cumsille; Jaime Sapag; Akwatu Khenti

    2015-01-01

    Esta investigación examina la relación entre el uso de drogas en estudiantes de una Universidad Pública en Villavicencio, Colombia, y su relación con el maltrato durante la niñez, utilizando como referente teórico la perspectiva bioecológica. Estudio exploratorio retrospectivo, con una muestra de 313 estudiantes de pregrado. El 10.2% de los encuestados refiere haber sido maltratado en la Infancia y la violencia de mayor uso fue la violencia física seguida de la violencia psicológica. El 56.9%...

  10. La Democracia en América Latina: la alternativa entre populismo y democracia deliberativa

    Guariglia, Osvaldo

    2011-06-01

    Full Text Available In Politics VI 2, 1317b 1-17, Aristotle defines «democracy» as follows: «the aim of democracy is, ideally, freedom from any interference of government, and, failing that, such freedom as comes from alternation of ruling and being ruled. It contributes, in this way, to a general system of liberty based on equality». Historically, this normative model shaped two possible political regimes, v. gr., popular or extreme democracy, based on direct participation of all citizens, as in Athens, and a «mixed constitution» containing oligarchic as well as democratic features, called «republican» in the roman tradition since Cicero. Modern democracy was the heir of both these Ancient regimes, tempered by the new conception of individual rights belonging to Modern thought from Hugo Grotius to the Universal Declaration of Human Rights. The representative constitution was, thus, the modern solution to the conflict between government of the majority and government of the laws. Since their Independence in the 19th century, Latin American democracies suffer from the unresolved tension between populism and the liberal constitutional regime. The neo-populism that grew in the last years of 20th century appears as a response and defiance to democracy’s unfulfilled promises. Against defenders of authoritarian populism, such as Ch. Mouffe and E. Laclau, I argue that deliberative democracy is a better response to them.

    En Política VI 2, 1317b 1-17, Aristóteles define así la democracia: «el rasgo esencial de la democracia es el vivir como se quiere sin ninguna interferencia y de aquí vino el de no ser gobernado, si es posible por nadie, y si no, por turnos. Esta característica contribuye a un sistema general de la libertad fundada en la igualdad». Este modelo normativo dio lugar, históricamente, a dos posibles regímenes políticos, la democracia popular o extrema, basada en la participación directa de todos los

  11. High temperature oxidation of SiC under helium with low-pressure oxygen. Part 3: β-SiC-SiC/PyC/SiC

    In the frame of generation IV gas-cooled fast reactor (GFR), the cladding materials currently considered is a SiC/SiC-based composite with a pyrocarbon interphase and a β-SiC coating on the surface to close the porosity (noted beta-SiC-SiC/PyC/SiC). These elements are subjected to temperatures going from 1300 to 1500 K in nominal operating conditions to 1900-2300 K in accidental conditions. The coolant gas considered is helium pressurized at 7 MPa. After a thermodynamic study carried out on the oxidation of beta-SiC under helium and low oxygen partial pressures, an experimental approach was made on β-SiC-SiC/PyC/SiC composites under active oxidation conditions (1400 ≤ T ≤ 2300 K; 0.2 ≤ pO2 ≤ 2 Pa). This study follows two preceding studies carried out on two polytypes of SiC: α (Part 1) and β (Part 2) under the same conditions. In these studies, the influence of the crystalline structure on the transition temperature between passive and active oxidation and on the mass loss rate was discussed. The experimental study allows to determine the oxidation rates in incidental and accidental conditions under pO2 = 0.2 and 2 Pa. The variation of the mass loss rates according to the temperature for β-SiC-SiC/PyC/SiC oxidized under pO2 = 0.2 and 2 Pa shows the existence of three domains in the zone of active oxidation. These tests also show the weak impact of the oxygen partial pressure on the mass loss rate of the material in this range of pressure for temperatures lower than 2070 K. On the other hand, beyond 2070 K, an increase of the mass loss rate leading to important damage of the material has been observed, at lower temperature under pO2 = 0.2 Pa than under pO2 = 2 Pa. This variation was associated to the effect of the oxygen partial pressure on the sublimation temperature of SiC. Similar experiments were performed on pre-oxidized samples and on the face without CVD β-SiC coating and both the results are close to the ones obtained for the face with the CVD

  12. 非晶硅/晶体硅(a-Si/c-Si)异质结%Property Investigation of a-Si/c-Si Hetero-Junction Structure

    汪建强; 高华; 张剑; 张松; 李晨; 叶庆好; 孟凡英

    2011-01-01

    通过对非晶硅/晶体硅(a-Si/c-Si)异质结能带不连续、发射结掺杂以及界面态密度进行分析,研究它们对a-Si/c-Si异质结的界面特性,以及a-Si(N+)/c-Si(P)结构电池性能的影响.研究发现,能带不连续以及a-Si发射结高掺杂有利于实现界面复合机制由以悬挂键复合主导的复合机制向由少数载流子复合占主导的SRH(Shockly-Read-Hall)复合机制转变,有效降低界面复合速率.AFORS-HET软件模拟显示:在c-Si(P)衬底掺杂浓度为1.6×1016cm-3时,a-Si(N+)发射结掺杂浓度大于1.5×1020cm-3是获得高电池效率的必要条件;与短路电流密度相比,开路电压受a-Si/c-Si界面态密度影响更明显.%T his paper investigated the influence ot a-hi/c-bi band ottset, amorphous silicon emitter doping concentration and interface defects density on interface property of a-Si/c-Si structure. Band offset in a-Si(N+ )/c-Si(P) hetero-junction and a-Si emitter high level doping is very useful for the transformation of recombination mechanism from dangling bond to SRH (Shockly-Read-Hall). AFORS-HET simulation indicates that a-Si(N+ ) emitter doping level of over 1. 5X1020 cm~3 on c-Si(P) is an indispensable condition for achieving high efficiency. Comparing with density of short circuit current, open circuit voltage of a-Si/c-Si structure cell is much more susceptible to interface defect density.

  13. SiCp/ZL109复合材料中SiC的界面行为%SiC PARTICLES AND THEIR INTERFACIAL BEHAVIOR IN SiCp/ZL109 COMPOSITES

    隋贤栋; 罗承萍; 欧阳柳章; 骆灼旋

    2000-01-01

    以常规TEM为工具,研究了SiCP/ZL109复合材料中数十个SiC颗粒及其界面,Si优先在SiC表面上形核、长大,形成界面Si,并形成大量SiC/Si界面.靠近SiC界面的Al基体中,普遍存在一层厚度小于1μm的"亚晶铝带",其内有大量位错.SiC与Al、SiC与Si之间虽然没有固定的晶体学位向关系,但是存在下列优先关系:(103)SiC//(111)Al,[110]SiC//[110]Al;(101)SiC//(111)Si;[110]SiC//[11]Si.

  14. Synthesis of biomorphaus SiC-ceramics

    Egelja Adela D.

    2007-01-01

    Full Text Available The carbothermal reduction processing of partially mineralized fir (Abies alba samples was used to obtain highly-porous SiC ceramics with cellular structure. The infiltration of TEOS (tetraetilortosilikat, Si(OC2H54 as a silica source, was conducted in order to carry out the mineralization process. Synthesis of the SiC was achieved with a C/SiO2 replica annealing at 1723 K in Ar atmosphere. The obtained samples were characterized using X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM and energy dispersive spectrometry (EDS. The experimental results revealed that the hierarchical bimorphous wood structure was preserved even after high-temperature treatment. Microstructural characterization of the ceramics revealed the presence of the P-SiC phase and traces of the a-SiC phase.

  15. Applicability of 32Si for groundwater dating

    The paper deals with the results of a study carried out to assess the applicability of 32Si for groundwater dating. Measurements of 32Si in soil samples of the unsaturated zone, of drainage waters and plant material provide the basis for estimating the 32Si initial concentration in groundwater. Different aquifers with groundwater of young and moderate ages have been selected for groundwater studies. For comparison purposes, tritium was found to be a suitable reference isotope. A quantitative interpretation of the 32Si data is generally complicated by geochemical processes, above all in the unsaturated zone. Favourable conditions concerning the use of 32Si in hydrogeology seem to exist in phreatic sand, in limestone and, depending on the thickness and composition of the unsaturated zone, in sandstone aquifers. Further improvement of the 32Si method requires deeper knowledge of the geochemical processes affecting this isotope

  16. Si nanocrystals for third generation solar cells

    Full text: Spontaneous self-structuring during spinodal decomposition of metastable Si-rich oxides is a very promising synthesis process of novel nanocrystalline Si structures for 3rd generation thin-film solar cells. This approach can be utilized to improve the single band gap silicon solar cells efficiency by spectrum management through the incorporation of larger band gap nanocrystalline silicon into the solar cell structure allowing a better use of the solar spectrum. Conventional techniques use high-temperature processing to obtain Si nanocrystals in SiO2 by Si-SiO2 phase separation. However, these processes are incompatible with glass substrates or thin-film stacked structures usually employed in mass production techniques (e.g in pilot lines for deployment of solar cells). An alternative approach capable of avoiding high temperature processing is the laser irradiation of substoichiometric silicon oxides. We present cw laser annealing of Si-rich oxide thin films with varying Si content to obtain Si nanocrystals embedded in silica. SiOx thin films with x4) gas was used as the Si source and two different precursor gasses, N2O and CO2, were used for oxygen incorporation. We have achieved the control of the Si ratio in the films by adjusting the relative gas flow ratios. Fine tuning the Si excess in SiOx and optimizing the annealing conditions is pursued to control the inter-nanocrystal distance to generate a network of Si nanocrystals with controlled Si/SiO2 phase separation. Our extensive computational studies of silicon nanowire networks based on realistic pseudopotential techniques have unraveled the systematics of the band gap variation under topological and structural variations. With the aid of these atomistic modeling tools, nanosponge networks are optimized for solar cell applications. The nanosponge network formation depends critically on the precise control of composition during deposition. In the case of SiOx films, it is expected that the network is

  17. Quantitative détermination of aluminium and silicon in SiO2 and Al2O3 by X ray fluorescence

    Sagrera, José Luis

    1966-09-01

    Full Text Available Not availableEn el presente trabajo, se describe la influencia de estos dos elementos entre si cuando se determinan sus contenidos en muestras binarias de Si02 y Al203. por fluorescencia de rayos X. En este mismo artículo se explica la corrección de estas influencias utilizando una fusión con tetraborato sódico, así como el procedimiento práctico para realizarla. Se detalla el procedimiento mediante fotografías tomadas en los momentos más interesantes del proceso de fusión.

  18. Crack-healing behavior induced by oxidation in SiN/SiC nanolaminated films

    The crack-healing behavior of SiN/SiC nanolaminated thin films in a high-temperature environment was investigated. Laminated films with a thickness of 1 μm were fabricated on a silicon substrate by ion-beam-assisted deposition. The number of layers was fixed to four, and the bilayer ratio of SiN to SiC was set to either 1 or 3. Cracked samples were heated in an air atmosphere at 600–1200 °C. In the case of the SiN/SiC nanolaminated film, the crack was perfectly filled with the oxide by heating at 1000 °C, whereas the crack of the SiN film was not healed. Moreover, the filled crack length of the SiN/SiC laminated film with a bilayer ratio of 1 was longer than that of the same type of film with a bilayer ratio of 3. These results suggest that inserting SiC layers in SiN films may confer crack-healing ability to SiN thin films. Moreover, the influence of heating on crack‐healing was investigated systematically. Crack‐healing was improved with increasing heating temperature and time. - Highlights: • SiN/SiC nano-laminated films exhibited a crack-healing ability. • Crack‐healing ability improved with a decrease in bilayer ratio of SiC to SiN. • The crack‐healing was promoted with an increase in heating temperature and time. • Crack‐healing is achieved by oxidation of SiC

  19. On the role of heterolayer relaxation in luminescence response of Si/SiGe:Er structures

    Krasilnikova, Ludmila; Stepikhova, Margarita; Drozdov, Yurij; Krasilnik, Zakharii [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Chalkov, Vadim; Shengurov, Vladimir [Physico-Technical Research Institute, Nizhny Novgorod State University, Gagarin Ave. 23, 603950 Nizhny Novgorod (Russian Federation)

    2011-03-15

    In this contribution we discuss the luminescence properties of Si/Si{sub 1-x}Ge{sub x}:Er/Si structures being of interest for a laser realization. The influence of the strain relaxation processes that take place in such kind of structures on their photoluminescence response at 1.54 {mu}m has been analyzed. The studies were performed for Si/Si{sub 1-x}Ge{sub x}:Er/Si structures with the different thickness of Si{sub 1-x}Ge{sub x}:Er layers, and consequently the degree of strain relaxation. It is shown that the structural defects arising in Si/Si{sub 1-x}Ge{sub x}:Er/Si structures due to the relaxation play only negligible role in their photoluminescence response. The contribution of the structural defects in the photoluminescence response at 1.54 {mu}m became apparent only in thin partially relaxed Si/Si{sub 1-x}Ge{sub x}:Er/Si structures, the photoluminescence spectra of which are represented by the broad ''defect related'' lines. Intense photoluminescence related with the optically active Er centers of different types was observed for the strained and completely relaxed Si/Si{sub 1-x}Ge{sub x}:Er/Si structures containing thick (d > 1 {mu}m) Si{sub 1-x}Ge{sub x}:Er layers. The external quantum efficiency of these structures reaches the value of 6.3 x 10{sup -5} at T =77 K. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Entre la realidad y el deseo: Una visión del asesoramiento

    Lourdes Montero

    2008-01-01

    Full Text Available Este artículo pretende destacar la importancia de aspectos como la colaboración, el trabajo en red y la dinamización de proyectos de innovación, como ejes fundamentales del asesoramiento psicopedagógico en un centro educativo. El trabajo colaborativo entre los distintos agentes implicados dentro y fuera de la institución escolar, así como la figura del asesor como dinamizador de cambios educativos orientados a la mejora, no sólo constituyen el supuesto de partida sino la meta deseada. Comenzaremos el trabajo con una necesaria aclaración de términos, dada la enorme diversidad de sentidos de los términos manejados, tratando de conceptualizar qué entendemos por asesorar y a qué tipo de asesores nos estamos refiriendo. Y si bien haremos una mención al conjunto de figuras que ocupan hoy el amplio paraguas del asesoramiento, nuestra mirada se focalizará en el asesoramiento interno en un centro educativo en el marco de la orientación. Inicialmente, partimos de reconocer el complejo entramado de perfiles y funciones de los distintos profesionales y la labor asesora de todos ellos a distintos niveles. Como hemos mencionado, nos centraremos en la figura del asesor interno (principalmente el orientador escolar y trataremos de ver cuál es su situación, tomando como punto de partida el conocimiento de cerca y desde dentro de la realidad gallega, en un rico y constante devenir de la práctica a la teoría y de ésta a la práctica. Nuestro trabajo se sitúa así en el marco de una perspectiva biográfica en la constitución del asesoramiento.

  1. Entre hybridité et univocité culturelles : aspects du multiculturalisme britannique à Bristol

    Vincent Latour

    2007-11-01

    Full Text Available Cet article tentera de montrer si la Grande-Bretagne en général et son modèle multiculturel en particulier peuvent s'accommoder de l’hybridité culturelle, voire l’encourager. A contrario le multiculturalisme britannique peut-il générer, sciemment ou non, un refus de cette hybridité ? Des données qualitatives de terrain, glanées entre 2000 et 2005, à la faveur des enquêtes menées à Easton et St Paul's, deux inner cities de Bristol, sont apportées pour appuyer l’analyse. L’évolution récente de ce modèle amènera des interrogations sur son devenir, ainsi que sur l'hybridation d'autres modes de gestion de la diversité en Europe, notamment le modèle républicain français.This article attempts to evaluate whether Britain in general and its multicultural model in particular can accomodate cultural hybridity and even encourage it, or whether British multiculturalism generates, knowingly or not, a refusal of that hybridity. Qualititative fieldwork between 2000 and 2005 in two inner city Bristol wards, Easton and St. Paul’s, is used to back up the analysis. The recent evolution of the British model leads to questions about its future, and the hybridation of other models of the governance of diversity in Europe, in particular the French republican model.

  2. First-principles calculations on atomic and electronic properties of Si(111)/6H-SiC(0001) heterojunction

    He, Xiao-Min; Chen, Zhi-Ming; Huang, Lei; Li, Lian-Bi

    2015-10-01

    Combining advanced transmission electron microscopy with high-precision first-principles calculations, the properties of Si(111)//6H-SiC(0001) (Si-terminated and C-terminated) heterojunction interface, such as work of adhesion, geometry property, electronic structure and bonding nature, are studied. The experiments have demonstrated that interfacial orientation relationships of Si(111)//6H-SiC(0001) heterojunction are Si[2-1-1]/6H-SiC[101¯0] and Si(111)/6H-SiC(0001). Compared with C-terminated interface, Si-terminated interface has higher adhesion and less relaxation extent.

  3. Study on in-situ Mg2Si/Al-Si composites with different compositions

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong

    2009-01-01

    Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary α-Al is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script-like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volum e fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

  4. 固相烧结SiC陶瓷%Solid State Sintered SiC Ceramics

    武安华; 曹文斌; 李江涛; 葛昌纯

    2001-01-01

    Solid state sintered SiC ceramics were obtained by hot pressing of α-SiC, β-SiC and 1%α-SiC +99%β-SiC powders with boride and carbon as additives. Two phase transforms of 3C→6H and 6H→4H occurred during sintering process. The in situ toughening SiC ceramics can't be obtained only by rod-like grains without the weak grain-boundary.%实验采用α-SiC、β-SiC和(1%α-SiC +99%β-SiC)作为起始粉末,以B、C为添加剂,热压烧结SiC陶瓷。其烧结过程中尽管发生多型体之间的转变,但其表现形式为α-SiC的6H→4H和β-SiC的3C→6H两种形式。尽管有大量的长柱状颗粒生成,但是由于没有弱的界面结合,不能原位增强。

  5. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect. PMID:27255897

  6. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  7. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Silicon carbide/silicon carbide (SiC/SiC) composites are of interest for components that will experience high radiation fields in the High Temperature Gas Cooled Reactor (HTGR), the Very High Temperature Reactor (VHTR), the Sodium Fast Reactor (SFR), or the Fluoride-cooled High-temperature Reactor (FHR). In all of the reactor systems considered, reactions of SiC/SiC composites with the constituents of the coolant determine suitability of materials of construction. The material of interest is nuclear grade SiC/SiC composites, which consist of a SiC matrix [high-purity, chemical vapor deposition (CVD) SiC or liquid phase-sintered SiC that is crystalline beta-phase SiC containing small amounts of alumina-yttria impurity], a pyrolytic carbon interphase, and somewhat impure yet crystalline beta-phase SiC fibers. The interphase and fiber components may or may not be exposed, at least initially, to the reactor coolant. The chemical compatibility of SiC/SiC composites in the three reactor environments is highly dependent on thermodynamic stability with the pure coolant, and on reactions with impurities present in the environment including any ingress of oxygen and moisture. In general, there is a dearth of information on the performance of SiC in these environments. While there is little to no excess Si present in the new SiC/SiC composites, the reaction of Si with O2 cannot be ignored, especially for the FHR, in which environment the product, SiO2, can be readily removed by the fluoride salt. In all systems, reaction of the carbon interphase layer with oxygen is possible especially under abnormal conditions such as loss of coolant (resulting in increased temperature), and air and/ or steam ingress. A global outline of an approach to resolving SiC/SiC chemical compatibility concerns with the environments of the three reactors is presented along with ideas to quickly determine the baseline compatibility performance of SiC/SiC.

  8. Switching Performance Evaluation of Commercial SiC Power Devices (SiC JFET and SiC MOSFET) in Relation to the Gate Driver Complexity

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    Silicon Carbide (SiC) power devices can provide a significant improvement of power density and efficiency in power converters. The switching performances of SiC power devices are often a trade-off between the gate driver complexity and the desired performance; this is especially true for SiC BJTs...... and JFETs. The recent introduction of SiC MOSFET has proved that it is possible to have highly performing SiC devices with a minimum gate driver complexity; this made SiC power devices even more attractive despite their device cost. This paper presents an analysis based on experimental results...... of the switching losses of various commercially available Si and SiC power devices rated at 1200 V (Si IGBTs, SiC JFETs and SiC MOSFETs). The comparison evaluates the reduction of the switching losses which is achievable with the introduction of SiC power devices; this includes analysis and considerations...

  9. The Stellar Imager (SI) Vision Mission

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita; Team, SI Vision Mission

    2006-01-01

    The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general and asteroseismic imaging of stellar interiors. SI is identified as a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap (May, 2005). SI will revolutionize ...

  10. Experimental and theoretical studies of Si-CN bonds to eliminate interface states at Si/SiO 2 interface

    Maida, Osamu; Asano, Akira; Takahashi, Masao; Iwasa, Hitoo; Kobayashi, Hikaru

    2003-09-01

    Cyanide treatment, which includes the immersion of Si in KCN solutions followed by a rinse, effectively passivates interface states at Si/SiO 2 interfaces by the reaction of CN - ions with interface states to form Si-CN bonds. X-ray photoelectron spectroscopy (XPS) measurements show that the concentration of the CN species in the surface region after the cyanide treatment is ˜0.25 at.%. Take-off angle-dependent measurements of the XPS spectra indicate that the concentration of the CN species increases with the depth from the Si/SiO 2 interface at least up to ˜2 nm when ultrathin SiO 2 layers are formed at 450 °C after the cyanide treatment. When the cyanide treatment is applied to metal-oxide-semiconductor (MOS) solar cells with structure, the photovoltage greatly increases, leading to a high conversion efficiency of 16.2% in spite of the simple cell structure with no pn-junction. Si-CN bonds are not ruptured by air mass 1.5 100 mW cm -2 irradiation for 1000 h, and consequently the solar cells show no degradation. Neither are Si-CN bonds broken by heat treatment at 800 °C performed after the cyanide treatment. The thermal and irradiation stability of the cyanide treatment is attributable to strong Si-CN bonds, whose bond energy is calculated to be 1 eV higher than that of the Si-H bond energy using a density functional method.

  11. Pd-Si binary bulk metallic glass

    YAO KeFu; CHEN Na

    2008-01-01

    Pd80+xSi20-x (x=0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature Tg, the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover, the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability, which can be greatly improved by fluxing treatment.

  12. Pd-Si binary bulk metallic glass

    2008-01-01

    Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content,the glass transition temperature Tg,the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover,the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability,which can be greatly improved by fluxing treatment.

  13. Impact of firing on surface passivation of p-Si by SiO2/Al and SiO2/SiNx/Al stacks

    Chen, J.; Cornagliotti, E.; Loozen, X.; Simoen, E.; Vanhellemont, J.; Lauwaert, J.; Vrielinck, H.; Poortmans, J.

    2011-12-01

    Firing impacts on surface passivation provided by a SiO2 and SiO2/SiNx stack with evaporated Al films are studied by capacitance-based techniques on MIS capacitors. For devices with insulator layers consisting solely of as-deposited SiO2, the densities of either interface states (Dit) or fixed charges (Qfc) are hardly influenced by firing. Capping the SiO2 layer with a SiNx layer results in a shift of the peak activation energy of Dit toward the valence band (Ev) of Si. Firing this SiO2/SiNx stack leads to an increase of Qfc, a reduction of Dit, and a moderate shift of peak activation energy of Dit toward Ev. Co-firing with the Al film on top significantly reduces the Qfc, Dit, and Dit peak activation energy, which is resulting from the atomic hydrogen passivation. These results are of particular interest for the development of solar cells with rear surface passivation and local contacts.

  14. SiD Letter of Intent

    Aihara, H., (Ed.); Burrows, P., (Ed.); Oreglia, M., (Ed.); Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; /Argonne, HEP; Zhang, Q.; /Argonne, HEP /Beijing, Inst. High Energy Phys.; Srivastava, A.; /Birla Inst. Tech. Sci.; Butler, J.M.; /Boston U.; Goldstein, Joel; Velthuis, J.; /Bristol U.; Radeka, V.; /Brookhaven; Zhu, R.-Y.; /Caltech.; Lutz, P.; /DAPNIA, Saclay; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women' s U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  15. Stress-impedance effects in layered FeSiB/Cu/FeSiB films with a meander line structure

    Stress-impedance (SI) effects were realized in layered FeSiB/Cu/FeSiB films with a meander line structure by magnetron sputtering on thin glass substrate. The SI effects were studied in the frequency range of 1-40MHz for the layered FeSiB/Cu/FeSiB films with different film thickness of FeSiB film and Cu layer. Experimental results show that the values of SI ratio increase nearly linear with the deflection of the layered FeSiB/Cu/FeSiB films at high frequencies, and a large negative SI ratio of -18.3% at a frequency of 25MHz with the deflection of 1000μm is obtained in the layered FeSiB/Cu/FeSiB films with a thicker FeSiB film, which is very attractive for the applications of stress sensors

  16. Recycling of Al-Si die casting scraps for solar Si feedstock

    Seo, Kum-Hee; Jeon, Je-Beom; Youn, Ji-Won; Kim, Suk Jun; Kim, Ki-Young

    2016-05-01

    Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3 N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al-30 wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells.

  17. Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

    The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100 degrees C and O2 concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100 degrees C and O2 concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies are in progress to evaluate the stability of these materials

  18. Experimental estimation of oxidation-induced Si atoms emission on Si(001) surfaces

    Ogawa, Shuichi, E-mail: ogasyu@tagen.tohoku.ac.jp; Tang, Jiayi; Takakuwa, Yuji [Institute Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2015-08-15

    Kinetics of Si atoms emission during the oxidation of Si(001) surfaces have been investigated using reflection high energy electron diffraction combined with Auger electron spectroscopy. The area ratio of the 1 × 2 and the 2 × 1 domains on a clean Si(001) surface changed with the oxidation of the surface by Langmuir-type adsorption. This change in the domain ratio is attributed to the emission of Si atoms. We can describe the changes in the domain ratio using the Si emission kinetics model, which states that (1) the emission rate is proportional to the oxide coverage, and (2) the emitted Si atoms migrate on the surface and are trapped at S{sub B} steps. Based on our model, we find experimentally that up to 0.4 ML of Si atoms are emitted during the oxidation of a Si(001) surface at 576 °C.

  19. Strain relaxation in nano-patterned strained-Si/SiGe heterostructure on insulator

    In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by Electron-Beam Lithography (EBL) and Reactive-Ion Etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of <15% is observed in pillars with a dimension of 150 nm x 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.

  20. Experimental estimation of oxidation-induced Si atoms emission on Si(001) surfaces

    Kinetics of Si atoms emission during the oxidation of Si(001) surfaces have been investigated using reflection high energy electron diffraction combined with Auger electron spectroscopy. The area ratio of the 1 × 2 and the 2 × 1 domains on a clean Si(001) surface changed with the oxidation of the surface by Langmuir-type adsorption. This change in the domain ratio is attributed to the emission of Si atoms. We can describe the changes in the domain ratio using the Si emission kinetics model, which states that (1) the emission rate is proportional to the oxide coverage, and (2) the emitted Si atoms migrate on the surface and are trapped at SB steps. Based on our model, we find experimentally that up to 0.4 ML of Si atoms are emitted during the oxidation of a Si(001) surface at 576 °C

  1. Characterization of SiC-SiC composites for accident tolerant fuel cladding

    Deck, C. P.; Jacobsen, G. M.; Sheeder, J.; Gutierrez, O.; Zhang, J.; Stone, J.; Khalifa, H. E.; Back, C. A.

    2015-11-01

    Silicon carbide (SiC) is being investigated for accident tolerant fuel cladding applications due to its high temperature strength, exceptional stability under irradiation, and reduced oxidation compared to Zircaloy under accident conditions. An engineered cladding design combining monolithic SiC and SiC-SiC composite layers could offer a tough, hermetic structure to provide improved performance and safety, with a failure rate comparable to current Zircaloy cladding. Modeling and design efforts require a thorough understanding of the properties and structure of SiC-based cladding. Furthermore, both fabrication and characterization of long, thin-walled SiC-SiC tubes to meet application requirements are challenging. In this work, mechanical and thermal properties of unirradiated, as-fabricated SiC-based cladding structures were measured, and permeability and dimensional control were assessed. In order to account for the tubular geometry of the cladding designs, development and modification of several characterization methods were required.

  2. Interface properties of Si-SiO2-Ta2O5 structure by cathodoluminescence spectroscopy

    We studied formation of the SiO2-T2O5 interface in the Si-SiO2-Ta2O5 structure using Cathodoluminescence Spectroscopy (CLS). Analyzing the evolution of CLS spectrum of the Si-SiO2 structure while depositing the Ta2O5 layer allowed to estimate an optical transmittance of the Ta2O5 layer and its band gap. Spectral features related to the formation of the SiO2-Ta2O5 interface were identified by comparison of the experimental CL spectrum of the Si-SiO2-Ta2O5 structure and its simulated counterpart. This formation involves a decomposition of silanol groups at the outer surface of the SO2 layer and creation of the SixTayO-type layer containing luminescence centers with the emission band centered at 3 eV photon energy

  3. Development of SiC/SiC composite for fusion application

    The recent efforts to develop SiC/SiC composite materials for fusion application under the collaboration with Japan and the USA are provided, where material performance with and without radiation damage has been greatly improved. One of the accomplishments is development of the high performance reaction sintering process. Mechanical and thermal conductivity are improved extensively by process modification and optimization with inexpensive fabrication process. The major efforts to make SiC matrix by CVI, PIP and RS methods are introduced together with the representing baseline properties. The resent results on mechanical properties of SiC/SiC under neutron irradiation are quite positive. The composites with new SiC fibers, Hi-Nicalon Type-S, did not exhibit mechanical property degradation up to 10 dpa. Based on the materials data recently obtained, a very preliminary design window is provided and the future prospects of SiC/SiC technology integration is provided. (author)

  4. Nanoscale structure of Si/SiO2/organics interfaces.

    Steinrück, Hans-Georg; Schiener, Andreas; Schindler, Torben; Will, Johannes; Magerl, Andreas; Konovalov, Oleg; Li Destri, Giovanni; Seeck, Oliver H; Mezger, Markus; Haddad, Julia; Deutsch, Moshe; Checco, Antonio; Ocko, Benjamin M

    2014-12-23

    X-ray reflectivity measurements of increasingly more complex interfaces involving silicon (001) substrates reveal the existence of a thin low-density layer intruding between the single-crystalline silicon and the amorphous native SiO2 terminating it. The importance of accounting for this layer in modeling silicon/liquid interfaces and silicon-supported monolayers is demonstrated by comparing fits of the measured reflectivity curves by models including and excluding this layer. The inclusion of this layer, with 6-8 missing electrons per silicon unit cell area, consistent with one missing oxygen atom whose bonds remain hydrogen passivated, is found to be particularly important for an accurate and high-resolution determination of the surface normal density profile from reflectivities spanning extended momentum transfer ranges, now measurable at modern third-generation synchrotron sources. PMID:25401294

  5. Hibridación entre la codorniz común (Coturnix coturnix y la codorniz de granja: estado de un problema de conservación

    M. Puigcerver

    2013-01-01

    Full Text Available Hibridación entre la codorniz común (Coturnix coturnix y la codorniz de granja: estado de un problema de conservación. La hibridación entre especies es un fenómeno ampliamente extendido que puede tener consecuencias en la conservación de la biodiversidad. En el presente artículo se hace una revisión del problema de conservación derivado de la suelta de codornices de granja en poblaciones silvestres de codorniz común (Coturnix coturnix. Estas codornices de granja han resultado ser, en la mayoría de casos, híbridos de codorniz común y codorniz japonesa (Coturnix japonica. Si no existen mecanismos de aislamiento reproductor, estas sueltas favorecerían la introgresión de genes de codorniz japonesa en las poblaciones de codorniz común; ello conllevaría que se produjera un “enjambre de híbridos” y la sedentarización de las poblaciones de codorniz, lo que comportaría muy probablemente su disminución en Europa. Esta amenaza es real, al haberse demostrado que no hay mecanismos de aislamiento reproductor, ni pre-cigóticos, ni post-cigóticos, ni ecológicos. Sin embargo, datos empíricos sugieren que a pesar de ello no se produce el temido “enjambre de híbridos”, sugiriéndose probablemente una mortalidad diferencial entre las dos especies como una posible explicación. Finalmente, se sugieren algunas medidas de gestión derivadas de la situación actual, entre las que destacaría un control genético que certifique el origen de los individuos criados en granja y la prohibición de efectuar sueltas de codornices japonesas o híbridos.

  6. Peter Shepheard Espacios intermedios entre la arquitectura y el paisaje

    Juan J. Tuset

    2015-05-01

    Full Text Available ResumenAcabada la Segunda Guerra Mundial, el Movimiento Moderno se debatió entre su continuidad o crisis, lo que llevó a numerosos arquitectos y críticos a formular teorías y adoptar actitudes disciplinares trasgresoras con el momento. Una de ellas fue la del arquitecto, urbanista y paisajista inglés Peter Shepheard quien desarrolló una actividad profesional, teórica y docente de la que se trasluce la relevancia del concepto in between como una de las claves defi nitorias del diseño arquitectónico en la segunda mitad del siglo XX. Para Shepheard el diseño moderno debía ser el encuentro entre la arquitectura, el urbanismo y el paisaje. Aseveración que vino precedida por diferentes tipos de obras arquitectónicas, proyectos urbanos, artículos y publicaciones sobre el diseño del paisaje y del jardínque le convirtieron en una voz de referencia en el contexto británico. Shepheard alentó a los paisajistas a convencerse de que las tres disciplinas anteriores convergen en un sola y que la responsabilidad de la joven profesión de arquitecto del paisaje es asumir el reto del diseño arquitectónico, urbano y paisajístico como un todo en la búsqueda y defi nición de espacios intermedios entre la arquitectura y el paisaje. AbstractAfter the Second World War, Modernism started to debate his continuity or crisis. This led many architects and critics to formulate theories and take up breaking disciplinary attitudes against that time. One of them was the English architect, urban planner and landscape designer Peter Shepheard who developed a professional, theoretical and academic career where the concept in between got relevance as one of the defi ning keys of the architectural design in the second half of the twentieth century. To Shepheard modern design should be the encounter between architecture, urbanism and landscape. This claim was preceded by different types of architectural works, urban projects, articles and publications on

  7. Synthesis, characterization, and wear and friction properties of variably structured SiC/Si elements made from wood by molten Si impregnation

    Dhiman, Rajnish; Rana, Kuldeep; Bengu, Erman;

    2012-01-01

    We have synthesized pre-shaped SiC/Si ceramic material elements from charcoal (obtained from wood) by impregnation with molten silicon, which takes place in a two-stage process. In the first process, a porous structure of connected micro-crystals of β-SiC is formed, while, in the second process......, molten Si totally or partly infiltrates the remaining open regions. This process forms a dense material with cubic (β-)SiC crystallites, of which the majority is imbedded in amorphous Si. The synthesis of preshaped “sprocket” elements demonstrates that desired shapes of such a dense SiC/Si composite...

  8. Polycrystalline SiC as source material for the growth of fluorescent SiC layers

    Kaiser, M.; Hupfer, T.; Jokubavicus, V.;

    2013-01-01

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport...... method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics....

  9. Fabrication and Properties of Ti3SiC2/SiC Composites

    YIN Hongfeng; FAN Qiang; REN Yun; ZHANG Junzhan

    2008-01-01

    Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and panicle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that:(1)Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature.(2)It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites.(3)When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12.8μm compared with the composites that the particle size of SiC added is 3μm.The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites.(4)Ti3SiC2/SiC composites were non-brittle fracture at room temperature.

  10. Passivation of surface-nanostructured f-SiC and porous SiC

    Ou, Haiyan; Lu, Weifang; Ou, Yiyu;

    The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper.......The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper....

  11. Raman scattering in Si/SiGe nanostructures: Revealing chemical composition, strain, intermixing, and heat dissipation

    Mala, S. A.; Tsybeskov, L., E-mail: tsybesko@njit.edu [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Lockwood, D. J.; Wu, X.; Baribeau, J.-M. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2014-07-07

    We present a quantitative analysis of Raman scattering in various Si/Si{sub 1-x}Ge{sub x} multilayered nanostructures with well-defined Ge composition (x) and layer thicknesses. Using Raman and transmission electron microscopy data, we discuss and model Si/SiGe intermixing and strain. By analyzing Stokes and anti-Stokes Raman signals, we calculate temperature and discuss heat dissipation in the samples under intense laser illumination.

  12. Development of MoSi2-SiC Component for Satellite Launch Vehicle

    G. P. Khanra; Abhay K. Jha; GiriKumar, S.; Mishra, D. K.; Sarvanan, T. T.; S C Sharma

    2012-01-01

    Intermetallic base MoSi2-SiC composite, an excellent high temperature oxidation-resistant material meant for the aerospace structural applications between 1600°C and 1700°C under oxidizing environment, has been developed successfully using powder metallurgy techniques. Mechanically milled (MM) MoSi2 powder, blended with SiC particulate was consolidated by vacuum hot pressing, yielded about 98.5% theoretical density. The composite has been characterized for physical, mechanical, and thermal pr...

  13. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23-24, 1997. The minimum bar size for 4-point flexure testing of SiC/SiC composite recommended by PNNL for irradiation effects studies is 30 {times} 6 {times} 2 mm{sup 3} with a span-to-depth ratio of 10/1.

  14. Nanocrystal Formation in Si Implanted Thin SiO2 Layers under the Influence of an Absorbing Interface

    Mueller, T.; Heinig, K. -H.; Moeller, W.

    2002-01-01

    Kinetic 3D lattice Monte Carlo studies are presented on Si nanocrystal (NC) formation by phase separation in 1 keV Si implanted thin SiO2 films. The simulation start from Si depth profiles calculated using the dynamic, high-fluence binary collision code TRIDYN. From the initial Si supersaturation, NCs are found to form either by nucleation, growth and Ostwald ripening at low Si concentrations. Or at higher concentrations, non-spherical, elongated Si structures form by spinodal decomposition, ...

  15. Ion beam induced crystallization of amorphous Si from NiSi2 precipitates: An in situ study

    By first growing NiSi2 precipitates in a-Si and then irradiating with a 150 keV Si beam, the authors have studied ion beam induced epitaxial crystallization (IBIEC) of Si initiated at a-Si/NiSi2 precipitate interfaces. The growth shape and its temperature dependence are studied in-beam via in situ transmission electron microscopy. Interface roughening is evidenced. Preliminary results for the Co-Si system are also reported

  16. Correlações entre parâmetros de adaptabilidade e estabilidade da produtividade de óleo em soja

    Rocha Maurisrael de Moura

    2006-01-01

    Full Text Available O objetivo deste trabalho foi determinar o grau de correlação entre parâmetros que avaliam a adaptabilidade e a estabilidade da produtividade de óleo em soja. Os parâmetros foram estimados a partir da análise de dados resultantes da avaliação de 93 linhagens de soja, divididas em três ciclos de maturação (28 precoces, 38 semiprecoces e 27 intermediárias. Os ensaios foram conduzidos em doze ambientes do município de Piracicaba, SP, Brasil. Os seguintes parâmetros foram correlacionados: média geral (m i, coeficiente de regressão (b i, ecovalência de Wricke (ômegaWi, ecovalência AMMI (ômegaAi, variância dos desvios da regressão (sigma2di e coeficiente de determinação (R²i. Utilizou-se a correlação (r de Sperman do ordenamento das linhagens, segundo cada parâmetro. As correlações entre m i e b i e entre os parâmetros de estabilidade entre si (ômegaWi, ômegaAi, sigma2di e R²i foram positivas e significativas (0,53 < r < 0,93 . As correlações entre os parâmetros de adaptabilidade e estabilidade foram baixas ou negativas e não significativas (-0,39 < r < 0,38, exceto entre b i e R²i (r = 0,49 e 0,89 para as linhagens precoces e intermediárias, respectivamente. Os parâmetros de estabilidade classificam a ordem das linhagens de forma similar e, provavelmente, pertencem ao mesmo conceito de estabilidade. Os resultados indicam que é difícil a seleção simultânea para adaptabilidade e estabilidade da produtividade de óleo em soja.

  17. Comportamiento a la corrosión electroquímica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyección térmica

    Pardo, A.

    2010-04-01

    Full Text Available The corrosion protection of Mg-Al alloys by flame thermal spraying of Al/SiCp composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiC particles (SiCp varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of micro-channels, largely in the vicinity of the SiC particles, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5-30 vol.% SiCp compared with the unreinforced thermal spray aluminium coatings.

    Se estudia, mediante espectroscopía de impedancia electroquímica en solución 3,5 % NaCl, la protección frente a la corrosión de aleaciones Mg-Al recubiertas por proyección térmica con materiales compuestos Al/SiCp. Se varió la fracción de volumen de las partículas de SiC (SiCp entre 5 y 30 %. Los recubrimientos efectuados por proyección térmica revelan un elevado número de microcanales, en la vecindad de las partículas de SiC, que facilitan la penetración del electrolito originando procesos de corrosión galvánica en los substratos de las aleaciones de magnesio. Un tratamiento posterior mediante la aplicación de una presión en frío reduce el grado de porosidad de los recubrimientos y mejora la unión, tanto entre el substrato y el recubrimiento como entre las partículas de aluminio y SiC, mejorando la resistencia a la corrosión de las aleaciones recubiertas. La efectividad de los recubrimientos disminuye ligeramente con la adición de SiCp cuando se comparan con los mismos recubrimientos de aluminio sin refuerzo.

  18. Microstructural stability of SiC and SiC/SiC composites under high temperature irradiation environment

    Silicon carbide continuous fiber-reinforced silicon carbide matrix composites (SiC/SiC composite) are attractive as the structural material of advanced energy systems, including nuclear fusion. The irradiation may affect the fiber/matrix interphases which are responsible for the pseudo-ductile fracture behavior of SiC/SiC composites. In this work, the investigation of the microstructural evolution of SiC/SiC composites in a fusion environment is performed by the dual-ion irradiation method. Reinforcements were Tyranno-SA and Hi-Nicalon Type-S. The displacement damage rate was up to 100 dpa. The irradiation temperature and He/dpa ratio were up to 1673 K and 60 appm, respectively. The microstructural modification induced by the dual-ion irradiation especially occurred in the interphase. The advanced SiC fiber did not shrink and the C/SiC multilayer interphase showed a superior microstructural stability against the dual-ion irradiation at high temperatures

  19. Structure of Si-capped Ge/SiC/Si (001) epitaxial nanodots: Implications for quantum dot patterning

    Petz, C. W.; Floro, J. A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Yang, D.; Levy, J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

    2012-04-02

    Artificially ordered quantum dot (QD) arrays, where confined carriers can interact via direct exchange coupling, may create unique functionalities such as cluster qubits and spintronic bandgap systems. Development of such arrays for quantum computing requires fine control over QD size and spatial arrangement on the sub-35 nm length scale. We employ electron-beam irradiation to locally decompose ambient hydrocarbons onto a bare Si (001) surface. These carbonaceous patterns are annealed in ultra-high vacuum (UHV), forming ordered arrays of nanoscale SiC precipitates that have been suggested to template subsequent epitaxial Ge growth to form ordered QD arrays. We show that 3C-SiC nanodots form, in cube-on-cube epitaxial registry with the Si substrate. The SiC nanodots are fully relaxed by misfit dislocations and exhibit small lattice rotations with respect to the substrate. Ge overgrowth at elevated deposition temperatures, followed by Si capping, results in expulsion of the Ge from SiC template sites due to the large chemical and lattice mismatch between Ge and C. Maintaining an epitaxial, low-defectivity Si matrix around the quantum dots is important for creating reproducible electronic and spintronic coupling of states localized at the QDs.

  20. Sr–Al–Si co-segregated regions in eutectic Si phase of Sr-modified Al–10Si alloy

    The addition of 200 ppm strontium to an Al–10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr–Al–Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of “impurity induced twinning”. - Highlights: ► Eutectic microstructure of a Sr-modified Al–10Si alloy was studied by high resolution methods. ► Nano-sized Sr–Al- and Al-enriched regions within the eutectic Si phase have been found ► Sr–Al- and Al-enriched regions are located at the intersections of Si twin lamellae. ► The findings are related to the postulated modification mechanism of impurity induced twinning

  1. Sr–Al–Si co-segregated regions in eutectic Si phase of Sr-modified Al–10Si alloy

    Timpel, M., E-mail: melanie.timpel@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Schlesiger, R. [Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster (Germany); Yamamoto, T. [HVEM Laboratory, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Isheim, D. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208-3108 (United States); Schmitz, G. [Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster (Germany); Matsumura, S. [HVEM Laboratory, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Banhart, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2013-09-15

    The addition of 200 ppm strontium to an Al–10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr–Al–Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of “impurity induced twinning”. - Highlights: ► Eutectic microstructure of a Sr-modified Al–10Si alloy was studied by high resolution methods. ► Nano-sized Sr–Al- and Al-enriched regions within the eutectic Si phase have been found ► Sr–Al- and Al-enriched regions are located at the intersections of Si twin lamellae. ► The findings are related to the postulated modification mechanism of impurity induced twinning.

  2. Scanning capacitance microscope study of a SiO2/Si interface modified by charge injection

    Tomiye, H.; Yao, T.

    We have investigated the local electrical properties of an SiO2/Si structure using a scanning capacitance microscope (SCaM) combined with an atomic force and a scanning tunneling microscope (AFM and STM). The electrical properties of the Si substrate and the SiO2/Si interface vary with position. In this experiment we have injected charge into the SiO2 and investigated the nature of charge storage at the SiO2/Si interface. We have used the combined microscope to apply a pulse to the SiO2/Si sample, causing charge to be trapped in the SiO2/Si interface. We could clearly detect the local variation of interface charge in a non-destructive manner using the SCaM and simultaneously by capacitance-voltage (C-V) characterization. The volume of the C-V curve shift along the voltage axis due to trapped charges is dependent upon the density of the trapped charges. In doing this experiment we show one of the many possible applications of the combined SCaM/AFM/STM.

  3. Gas permeability of SiC/SiC composites as fusion reactor material

    Permeability of helium gas in SiC/SiC composites material, which is one of the most important properties in application of SiC/SiC composite for first wall and blanket of fusion reactors, was studied by using a vacuum apparatus. Three tubular and two flat plate SiC/SiC composites were prepared by different preparation processes. The measurement of permeability coefficient of helium gas was carried out with pressure ranging from 102 to 105 Pa at room temperature. The permeability coefficient of the SiC/SiC composite largely depended on the preparation method. In three tubular materials, the SiC/SiC composite made by both polymer impregnation and pyrolysis (PIP) and melt infiltration (MI) methods showed the lowest permeability, 9.1x10-7 m2/s, which was approximately two orders of magnitude smaller than one of the material made only by PIP method. The permeability of the flat plate SiC/SiC composites made by both liquid phase sintering (LPS) and hot pressing (HP) was approximately 1.5x10-9-4.0x10-11 m2/s. The difference of permeability was related to the microscopic structure, i.e. pores and cracks

  4. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-01

    Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod. PMID:26818131

  5. Further Developments in Modeling Creep Effects Within Structural SiC/SiC Components

    Lang, Jerry; DiCarlo, James A.

    2008-01-01

    Anticipating the implementation of advanced SiC/SiC composites into turbine section components of future aero-propulsion engines, the primary objective of this on-going study is to develop physics-based analytical and finite-element modeling tools to predict the effects of constituent creep on SiC/SiC component service life. A second objective is to understand how to possibly manipulate constituent materials and processes in order to minimize these effects. Focusing on SiC/SiC components experiencing through-thickness stress gradients (e.g., airfoil leading edge), prior NASA creep modeling studies showed that detrimental residual stress effects can develop globally within the component walls which can increase the risk of matrix cracking. These studies assumed that the SiC/SiC composites behaved as isotropic viscoelastic continuum materials with creep behavior that was linear and symmetric with stress and that the creep parameters could be obtained from creep data as experimentally measured in-plane in the fiber direction of advanced thin-walled 2D SiC/SiC panels. The present study expands on those prior efforts by including constituent behavior with non-linear stress dependencies in order to predict such key creep-related SiC/SiC properties as time-dependent matrix stress, constituent creep and content effects on composite creep rates and rupture times, and stresses on fiber and matrix during and after creep.

  6. Advances in SiC/SiC Composites for Aero-Propulsion

    DiCarlo, James A.

    2013-01-01

    In the last decade, considerable progress has been made in the development and application of ceramic matrix composites consisting of silicon carbide (SiC) based matrices reinforced by small-diameter continuous-length SiC-based fibers. For example, these SiC/SiC composites are now in the early stages of implementation into hot-section components of civil aero-propulsion gas turbine engines, where in comparison to current metallic components they offer multiple advantages due to their lighter weight and higher temperature structural capability. For current production-ready SiC/SiC, this temperature capability for long time structural applications is 1250 degC, which is better than 1100 degC for the best metallic superalloys. Foreseeing that even higher structural reliability and temperature capability would continue to increase the advantages of SiC/SiC composites, progress in recent years has also been made at NASA toward improving the properties of SiC/SiC composites by optimizing the various constituent materials and geometries within composite microstructures. The primary objective of this chapter is to detail this latter progress, both fundamentally and practically, with particular emphasis on recent advancements in the materials and processes for the fiber, fiber coating, fiber architecture, and matrix, and in the design methods for incorporating these constituents into SiC/SiC microstructures with improved thermo-structural performance.

  7. Microstructure and abrasive wear studies of laser clad Al-Si/SiC composite coatings

    Anandkumar, R.; Colaco, R.; Ocelik, V.; De Hosson, J. Th. M.; Vilar, R.; Gyulai, J; Szabo, PJ

    2007-01-01

    Surface coatings of Al-Si/SiC metal-matrix composites were deposited on Al-7 wt. % Si alloy substrates by laser cladding. The microstructure of the coatings was characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure of the coating mate

  8. The effect of biaxial strain on impurity diffusion in Si and SiGe

    Larsen, Arne Nylandsted; Zangenberg, Nikolaj; Fage-Pedersen, Jacob

    2005-01-01

    Results from diffusion studies of different impurities in biaxially strained Si and Si"1"-"xGe"x for low x-values will be presented. The structures are all molecular-beam epitaxy (MBE) grown on strain-relaxed Si"1"-"xGe"x layers, and the impurity profiles are introduced during growth. We have in...

  9. Preparation of Si3N4–SiC composites by microwave route

    M Panneerselvam; K J Rao

    2002-12-01

    Si3N4–SiC composites have been microwave sintered using -Si3N4 and -SiC as starting materials. Si3N4 rich compositions (95 and 90 vol.% Si3N4) have been sintered above 96% of theoretical density without using any sintering additives in 40 min. A monotonic decrease in relative density is observed with increase in SiC proportion in the composite. Decrease in relative density has manifested in the reduction of fracture toughness and microhardness values of the composite with increase in SiC content although the good sintering of matrix Si3N4 limits the decrease of fracture toughness. Highest value of fracture toughness of 6.1 MPa m1/2 is observed in 10 vol.% SiC composite. Crack propagation appears to be transgranular in the Si3N4 matrix and the toughening of the composites is through crack deflection around hard SiC particles in addition to its debonding from the matrix.

  10. About the International System of Units (SI) Part III. SI Table

    Aubrecht, Gordon J., II; French, Anthony P.; Iona, Mario

    2012-01-01

    Before discussing more details of SI, we will summarize the essentials in a few tables that can serve as ready references. If a unit isn't listed in Tables I-IV, it is not part of SI or specifically allowed for use with SI. The units and symbols that are sufficient for most everyday applications are given in bold.

  11. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    Dobrovolskiy, S.; Yakshin, A. E.; Tichelaar, F. D.; Verhoeven, J.; E. Louis,; F. Bijkerk,

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10-20 nm were produced by sequential deposition of Si and implantation of 1 key CHx+ ions. Only about 3% of the implanted carbon was transferred into the SIC, with a thin, 0.5-1 nm, buried SIC layer being formed. We investigat

  12. Effect of Nano-SiC Particles on the Performance and Microstructure of Si3N4/SiC Composite Ceramics%纳米SiC对Si3N4/SiC复相陶瓷性能及显微结构的影响

    张伟儒; 李勇; 陈文

    2007-01-01

    In this paper, Si3 N4/SiC composite ceramics were prepared from two different raw materials with nano-SiC particles or organic precursor. Effect of nano-SiC particles on the performance and microstructure of the Si3 N4/SiC ceramics was studied, and the relation between reinforced mechanism and microstructure of materials was also investigated.%本研究通过采用纳米SiC粉体及有机前驱体两种途径,制备了Si3N4/SiC粒子(Si3 N4/纳米SiC)复相陶瓷,研究了纳米SiC对Si3 N4/SiC复相陶瓷性能及显微结构的影响,讨论了材料强化的机制与显微结构的关系.

  13. Assimetrias entre os competidores nos leilões da ANP

    Eric Universo Rodrigues Brasil

    2013-09-01

    Full Text Available Este artigo investiga assimetrias entre os concorrentes dos leilões para exploração de petróleo no Brasil, através da comparação estatística das distribuições dos lances, estimadas por procedimentos não paramétricos. Uma análise exploratória dos lances empreendidos, contendo diversas combinações de jogadores, corroborou a expectativa da presença de assimetrias em favor da Petrobras e da OGX. Comparamos as distribuições e testamos diferenças a partir do teste de Kolmogorov-Smirnov. Os resultados reforçam a hipótese de assimetrias, mas há evidências estilizadas compatíveis com a presença de assimetrias de natureza informacional e também de custos.

  14. Quelques liens entre aspects discrets et continus dans jeux dynamiques

    Maldonado Lopez, Juan Pablo

    2014-01-01

    Cette thèse étudie les liens entre a) les jeux en temps discret et continu, et b) les jeux à très grand nombre de joueurs identiques et les jeux avec un continuum de joueurs. Une motivation pour ces sujets ainsi que les contributions principales de cette thèse sont présentées dans le Chapitre 1. Le reste de la thèse est organisé en trois parties. La Partie I étudie les jeux différentiels à somme nulle et à deux joueurs. Nous décrivons dans le Chapitre 3 trois approches qui ont été proposées d...

  15. Cultura organizacional: sinergias e alergias entre Hofstede e Trompenaars

    Daniel Pacheco Lacerda

    2011-10-01

    Full Text Available Entre os diferentes elementos a serem considerados na gestão atualmente, os aspectos culturais têm se colocado na centralidade das discussões organizacionais. Essa posição deriva do fato de que a vantagem competitiva sustentável se origina da compreensão, respeito e utilização das diferenças de hábitos, práticas, pontos de vistas e competências. Empresas com atuação local ou global precisam atentar para as características oriundas de seu capital humano. O presente trabalho busca apresentar algumas evidências das implicações culturais a partir do prisma das dimensões culturais. Para isso é realizada uma breve revisão sobre o tema, em seguida são discutidas algumas repercussões para as organizações.

  16. Relation entre la microtexture et l'adhérence

    DO, MT

    2005-01-01

    Une synthèse des travaux menés au LCPC depuis 10 ans sur la microtexture des surfaces de chaussée est présentée. Des progrès ont été accomplis dans la mesure et la caractérisation de la microtexture. Les nouveaux descripteurs de la microtexture ont été intégrés dans un modèle de contact pour le calcul d'un coefficient de frottement à basse vitesse. L'apport de la relation entre la microtexture et le frottement à basse vitesse à la prévision de l'adhérence est ensuite traité. La variation de l...

  17. Coherencia entre el ideario y los valores en el aula.

    Carbó-González, José María

    2013-01-01

    Estamos en tiempos de crisis, y esto es innegable, aunque a parte de las dificultades económicas, mucha gente, entre ellas el Dr. Horacio Krell, director de Ilvem (y creador del método que lleva el mismo nombre) afirman que estamos también ante una crisis de valores, y eso no es nada más que la substitución de unos valores tradicionales por unos de nuevos. El cambio no es nada nuevo, constantemente estamos en proceso de transformación, y como decía Sigmund Freud: “la herejía de una época es l...

  18. Relaciones entre actividad física y salud

    Blasco, Tomás; Capdevila Ortís, Lluís; Cruz Feliu, Jaume

    1994-01-01

    En este trabajo se describe la evolución de las características que han guiado la labor de investigación e intervención en el campo de estudio de las relaciones entre actividad física y salud a lo largo de la última década, señalando las aportaciones realizadas por el grupo de investigación al que pertenecen los autores. Asimismo, se plantean algunas sugerencias respecto a las directrices a seguir en nuestro país en este área de estudio e intervención a partir de la situación actual

  19. La Cooperación Internacional entre Servicios

    Pulido Gragera, Julia

    2005-01-01

    Full Text Available Los nuevos requerimientos en materia de seguridad que la comunidad internacional tiene que asumir como consecuencia de las nuevas amenazas y riesgos, obligan a que los Servicios de Inteligencia y de Información, objeto de análisis de este artículo, incrementen y mejoren la colaboración y cooperación entre ellos. En este sentido la aspiración de los Estados por poseer el máximo nivel de seguridad cediendo el mínimo de soberanía, se constituye como uno de los objetivos principales de los mismos, dificultad que se presenta, en la actualidad, para poder lograr una efectiva coordinación multilateral.…

  20. Elevages laitiers à bas intrants : entre traditions et innovations

    Delaby, Luc; Fiorelli, Jean-Louis

    2014-01-01

    Après une période de grande stabilité des prix et des volumes produits, encadrée par une politique agricole commune forte, la filière laitière française entre dans une zone de turbulences et d’incertitudes. L’augmentation de la demande alimentaire mondiale, associée à l’abandon imminent des quotas laitiers devraient créer un climat d’enthousiasme et favoriser le développement de la production laitière en Europe. Mais ces dérégulations aboutissent aussi à de fortes tensions sur le marché mondi...

  1. estudo comparativo entre escolas públicas e privadas

    Vieira, Fernanda Maria Mesquita

    2012-01-01

    Este estudo tem como objetivo averiguar se existe satisfação profissional e sócio-organizacional entre membros de Direções de Escolas do Básico e do Secundário, do ensino público e privado, nomeadamente porque a investigação, nos domínios da gestão e da psicologia do trabalho e das organizações, preconiza que a satisfação profissional e a sócio-organizacional, direta ou indiretamente, se encontram ligadas à produtividade e à realização pessoal, aspetos estes que não são alheios às atuais polí...

  2. Interesse e conhecimento em cirurgia refrativa entre estudantes de medicina

    Kara José Flávio Cotait; Passos Lúcia Battistella; Jervásio Ana Carolina; Salomão Gustavo Henrique

    2002-01-01

    Objetivo: Realizou-se um estudo em estudantes da Faculdade de Medicina do ABC a fim de analisar e relacionar a freqüência de usuários de correção óptica, o tipo de vícios de refração, o número de pessoas submetidas à cirurgia refrativa e o conhecimento e interesse por essa operação. Métodos: realizou-se um levantamento entre estudantes de medicina da Faculdade de Medicina do ABC, no período de 19 a 21 de junho de 2000. Foi utilizado um questionário auto-aplicável como instrumento de coleta de...

  3. Risco ocupacional de adquirir tuberculose entre trabalhadores de enfermagem hospitalar

    Elisabete Takeda

    2001-09-01

    Full Text Available Nos hospitais, os indivíduos tuberculosos são atendidos por vários profissionais e dentre eles os trabalhadores de enfermagem. Esses trabalhadores estão sujeitos a riscos de infecção tuberculosa. O estudo objetivou: levantar o número de trabalhadores de enfermagem do hospital que adquiriram tuberculose, e as características gerais em um período pré determinado; levantar a morbidade dessa doença e discutir o risco ocupacional entre estes trabalhadores. Em um ano os trabalhadores apresentaram risco 3.86 vezes maior e em outro, 1.47 vezes maior de adquirir a doença. Neste estudo a tuberculose foi considerada de risco ocupacional para os trabalhadores de enfermagem.

  4. Re-encontro: entre memória e identidade

    Diogo, Dora Maria Tracana

    2012-01-01

    Nesta dissertação, trabalhei sobre a questão de identidade e a sua ligação à memória. Inspirei- me na aldeia dos meus avós, “Panoias”. Aldeia onde passei bons momentos da minha infância, e que tanto peso teve na minha formação como pessoa. A experiencia pessoal do contacto com a aldeia, tão diferente da cidade escolhida por minha mãe para habitar (Coimbra) - e a luta atual com a doença - levou-me a procurar explorar o tema, “RE-ENCONTRO: ENTRE MEMÓRIA E IDENTIDADE”, onde pro...

  5. Entre l'Europe et l'Amérique

    Rupnik, Jacques

    2003-01-01

    Le 16 avril 2003 fut signé à Athènes, au pied du Panthéon, le traité d'adhésion de dix nouveaux membres de l'Union européenne. Huit d'entre eux étaient des pays d'Europe centrale (la Pologne, la République tchèque, la Slovaquie, la Hongrie, la Slovénie, l'Estonie, la Lettonie et la Lituanie), et il semblait que l'on scellait là le « retour en Europe » espéré dans les pays ex-communistes depuis 1989. Pourtant, ce qui aurait dû être une fête de l'unification de l'Europe fut vécu comme un moment...

  6. Atomic structure of carbon-induced Si(001)c(4x4) reconstruction as a Si-Si homodimer and C-Si heterodimer network

    A combination of low-energy electron diffraction, x-ray and ultraviolet photoelectron spectroscopy, and scanning-tunneling microscopy studies, in conjunction with ab initio calculations leads us to suggest a model for the carbon (C)-induced Si(001)c(4x4) atomic structure. This surface superstructure is obtained in a defined range of C2H4 exposures at 600 deg. C. Experimental probes show that the c(4x4) superstructure involves C atoms in both surface and subsurface sites. This is reflected in well-marked features in photoemission valence- and core-level spectra. Surface carbon atoms are stabilized in Si-C heterodimers, with a surface density of about 0.25 monolayer (ML) [i.e., two C atoms per c(4x4) unit cell of eight atoms]. In the subsurface region, carbon atoms substitute for Si atoms in well-defined sites of the third or fourth layers of the Si substrate. The subsurface C density increases with C2H4 exposure time up to a limit value of about 0.5 ML, within the c(4x4) surface structure. Further exposure disrupts the c(4x4) reconstruction and leads to a (2x1) low-energy electron diffraction pattern. Interaction with atomic hydrogen shows that the surface contains a mixture of heterodimers (Si-C) and homodimers (Si-Si), with an 1:1 proportion. These assignments are supported by first-principle calculations, which yield valence band and core level states in fairly good agreement with the experiment. Furthermore, total energy calculations strongly favor C incorporation in surface Si-C dimers and in third and fourth layer sites, and rule out C incorporation in sites of the second Si layer. The most stable c(4x4) surface configuration, suggested by our calculations, consists of alternate Si-C and Si-Si dimer lines. In such a configuration, surface carbon atoms in Si-C dimers induce a surface stress that leads to charge redistribution and atomic relaxation of the adjacent Si-Si dimers, consistent with scanning-tunneling microscopy images. Additional C atoms (in excess

  7. Silane photoabsorption spectra near the Si 2p thresholds: the geometry of Si 2p excited SiH4

    张卫华; 许如清; 李家明

    2003-01-01

    Based on the multiple-scattering self-consistent-field method, we have studied the photoabsorption spectra near the Si 2p thresholds of silane. According to our calculations, the clear assignments of the inner-shell photoabsorption spectra are provided. In comparison with the high-resolution experimental spectra, the geometric structure of the Si 2p-excited SiH4** is recommended to be of a C2v symmetry. More specifically, the Si 2p-excited Si4** have two bond lengths of 2.50 a.u. and another two bond lengths of 2.77 a.u., and the corresponding two bond angles are 104.0° and 112.5° respectively.

  8. Thermochemical instability effects in SiC-based fibers and SiC{sub f}/SiC composites

    Youngblood, G.E.; Henager, C.H.; Jones, R.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1997-08-01

    Thermochemical instability in irradiated SiC-based fibers with an amorphous silicon oxycarbide phase leads to shrinkage and mass loss. SiC{sub f}/SiC composites made with these fibers also exhibit mass loss as well as severe mechanical property degradation when irradiated at 800{degrees}C, a temperature much below the generally accepted 1100{degrees}C threshold for thermomechanical degradation alone. The mass loss is due to an internal oxidation mechanism within these fibers which likely degrades the carbon interphase as well as the fibers in SiC{sub f}/SiC composites even in so-called {open_quotes}inert{close_quotes} gas environments. Furthermore, the mechanism must be accelerated by the irradiation environment.

  9. Nanostructured Si-alloys for silicon solar cells

    Ding, Kaining

    2015-01-01

    In order to initiate further progress in silicon (Si) photovoltaics, a next-generation of Si solar cell concepts targeting both high performance and low-cost production needs to emerge. The objective of this thesis is to fabricate and characterize Si nanostructures embedded in a Si alloy matrix and implement these novel materials into Si based photovoltaic devices. In particular, silicon quantum dots (Si-QDs) in a silicon carbide (SiC)/Si-rich silicon oxide (SiOx) hetero-superlattice (HSL) st...

  10. Fortunata y Jacinta, entre la libertad y la orden

    Julio Rodríguez Puértolas

    2007-07-01

    Full Text Available Parece evidente que en Fortunata y Jacinta hay una presencia, como de trasfondo, de una acuciante realidad sociohistórica en la España de la época, el anarquismo, y ello a través de diversos mecanismos, que van desde alusiones directas a sucesos del momento hasta simples pero significativas palabras de varios personajes. Recordemos que la acción de la novela (publicada en 1886-1887 tiene lugar entre 1869 y 1876, esto es, desde la fecha en que se promulga la constitución radical subsiguiente a La Gloriosa hasta pocos meses antes de la proclamación de la de 1876, la de la Restauración. Entre ambas fechas, recordemos también, han ocurrido algunas cosas de importancia al respecto, dentro y fuera de España: 1869, creación de la sección española de la Asociación Internacional de Trabajadores; 1870, primer congreso obrero; 1870-1871, la Comuna de París, debate y condena de la Internacional en las Cortes Españolas; en 1873, una vez proclamada la República, epidemia de cantonalismo y sublevación anarquista de Alcoy ... El Partido Socialista Obrero Español, por otro lado, no sería fundado hasta 1879, tres años después de la muerte de Fortunata. A la luz de tales datos, no puede extrañar que al marqués de Casa-Muñoz «lo que le tiene el alma en un hilo es que se levante la masa obrera». Tampoco sorprende que, desde otra perspectiva, Juan Pablo Rubín «descubra»en cierto momento el anarquismo, esto es.

  11. Enemigos de La Habana entre los patriotas gaditanos

    Vázquez Cienfuegos, Sigfrido

    2009-01-01

    Con la expresión "enemigos de La Habana" los hacendados criollos cubanos hacían referencia a los intereses monopolísticos que, asentados en Cádiz y representados en el Consulado, trataban por todos los medios de mantener las prerrogativas exclusivistas que habían disfrutado durante años. Si bien esta pugna se había mantenido durante las últimas décadas del siglo XVIII, fue durante el periodo en que Cádiz encarnó la resistencia frente al invasor francés cuando el enfrentamiento alcanzó el grad...

  12. La prostitution au Tonkin colonial, entre races et genres

    Tracol-Huynh, Isabelle

    2010-01-01

    Cet article entend sortir de l’histoire de la guerre, qui marque encore très fortement l’historiographie du Viêt-Nam, pour s’intéresser à la dimension sociale et sexuelle de la colonisation à travers une étude de la prostitution au Tonkin. Il s’agit de faire ici l’histoire sociale de ces groupes (colonisateurs-colonisé(e)s, hommes-femmes), de leurs constructions mutuelles et parallèles, ainsi que leurs relations plus ou moins conflictuelles dans le cadre de l’État colonial. En effet, si la do...

  13. On iron contamination in mechanically alloyed Cr-Si powders

    The present work reports on iron contamination and phase transformation during high-energy ball milling from high-purity elemental powder Cr-25Si, Cr-37.5Si, Cr-50Si, and Cr-66Si mixtures (at%) and their subsequent heat treatment. Samples were characterized in the as-milled state as well as after heat treatment by X-ray diffraction (XRD), scanning electron microscopy (SEM), and microanalysis via energy dispersive spectrometry (EDS). Only Cr peaks were observed in Cr-25Si and Cr-37.5Si powders after milling for 200 h, suggesting that amorphous phases can be formed. In Cr-50Si and Cr-66Si powders, the CrSi and CrSi2 phases were formed during ball milling, respectively. In Cr-25Si and Cr-50Si milled powders, heat-treated at 1200 deg. C for 4 h, the formation of the Cr3Si and CrSi phases dissolving up to 15 and 16.9 at%Fe, respectively, was noted. In addition, the ternary Cr9Fe9Si2 phase was also formed in heat-treated Cr-25Si powders. A small amount of Cr5Si3 and CrSi2 was formed in heat-treated Cr-37.5Si and Cr-66Si powders, respectively

  14. Lateral boron distribution in polycrystalline SiC source materials

    Linnarsson, M. K.; Kaiser, M.; Liljedahl, R.;

    2013-01-01

    Polycrystalline SiC containing boron and nitrogen are used in growth of fluorescent SiC for white LEDs. Two types of doped polycrystalline SiC have been studied in detail with secondary ion mass spectrometry: sintered SiC and poly-SiC prepared by sublimation in a physical vapor transport setup. The...

  15. Encontro entre teleologia e deontologia: uma análise a partir da interpretação contemporânea de Paul Ricoeur

    Élsio José Corá

    2011-08-01

    Full Text Available http://dx.doi.org/10.5007/1677-2954.2010v9n1p43Este trabalho pretende analisar a relação entre teleologia e deontologia, sob o ponto de vista contemporâneo de Paul Ricoeur. Objetiva, ainda, fazer uma classificação dos conceitos utilizados nessa relação, que incluem a estima de si, respeito de si, vida boa, solicitude e alteridade, conceitos tratados, principalmente no sétimo e oitavo capítulo da obra O si-mesmo como um outro. O estudo revela que para interrelacionar as propostas da ética teleológica (aristotélica e a deontológica (kantiana é preciso retomar a estrutura conceitual desenvolvida por Ricoeur, ou seja a tese da primazia da ética sobre a moral, bem como no desenvolvimento dessa tese, a necessidade da ética passar pelo crivo da norma.

  16. Modification of Mg{sub 2}Si in Mg–Si alloys with gadolinium

    Ye, Lingying; Hu, Jilong, E-mail: hjlong@csu.edu.cn; Tang, Changping; Zhang, Xinming; Deng, Yunlai; Liu, Zhaoyang; Zhou, Zhile

    2013-05-15

    The modification effect of gadolinium (Gd) on Mg{sub 2}Si in the hypereutectic Mg–3 wt.% Si alloy has been investigated using optical microscope, scanning electron microscope, X-ray diffraction and hardness measurements. The results indicate that the morphology of the primary Mg{sub 2}Si is changed from coarse dendrite into fine polygon with the increasing Gd content. The average size of the primary Mg{sub 2}Si significantly decreases with increasing Gd content up to 1.0 wt.%, and then slowly increases. Interestingly, when the Gd content is increased to 4.0 and 8.0 wt.%, the primary and eutectic Mg{sub 2}Si evidently decrease and even disappear. The modification and refinement of the primary Mg{sub 2}Si is mainly attributed to the poisoning effect. The GdMg{sub 2} phase in the primary Mg{sub 2}Si is obviously coarsened as the Gd content exceeds 2.0 wt.%. While the decrease and disappearance of the primary and eutectic Mg{sub 2}Si are ascribed to the formation of vast GdSi compound. Therefore, it is reasonable to conclude that proper Gd (1.0 wt.%) addition can effectively modify and refine the primary Mg{sub 2}Si. - Highlights: ► Proper Gd (1.0 wt.%) addition can effectively modify and refine the primary Mg{sub 2}Si. ► We studied the reaction feasibility between Mg and Si, Gd and Si in Mg–Gd–Si system. ► We explored the modification mechanism of Gd modifier on Mg{sub 2}Si.

  17. Characterization of Si3N4-Al interface after corrosion tests Caracterização da interface Si3N4-Al após testes de corrosão

    C. dos Santos

    2003-12-01

    Full Text Available Silicon nitride is a covalent ceramic material of high corrosion resistance and mechanical stability at elevated temperatures. Due to these properties, its use in metallurgical processes, such as the casting of alloys, is increasing. Therefore, the characterization of the interface between Si3N4 and the casted metal is of great importance to investigate possible interactions, which might deteriorate the ceramic mould or contaminate the metal. In this work, the use of Si3N4 as crucible material for Al-casting has been studied, by investigating the corrosion attack of liquid Al at a temperature of 1150 ºC during 30 days in air. The interface was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. It has been found that due to superficial oxidation two oxide layers form - SiO2 on Si3N4 and Al2O3 on Al - which effectively hinder further reactions under the conditions studied, confering high corrosion resistance to the Si3N4 crucible.Nitreto de silício (Si3N4 é um material cerâmico covalente de elevada resistência à corrosão e estabilidade mecânica em temperaturas elevadas. Devido a essas propriedades, sua utilização em processos metalúrgicos, tais como em fundição de ligas metálicas, é crescente. Desta forma, a caracterização da interface entre Si3N4 e metais fundidos é de grande interesse para investigar possíveis interações as quais poderão deteriorar o material cerâmico e/ou contaminar o metal. Nesse trabalho o uso de Si3N4 como material base de cadinhos para fundição de alumínio foi estudado, pela investigação do ataque corrosivo de Al líquido a 1150 ºC durante 30 dias, ao ar. A interface foi caracterizada por difração de raios X, microscopia eletrônica de varredura e espectroscopia de energia dispersiva. É encontrado que devido à oxidação superficial dois óxidos se formam - SiO2 no Si3N4 e Al2O3 no Al - os quais evitam possíveis reações sob as condi

  18. Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

    Effects of composition, mold temperature, rotating rate and modification on microstructure of centrifugally cast Zn-27Al-xMg-ySi alloys have been investigated. In situ composites of Zn-27Al-6.3Mg-3.7Si and Zn-27Al-9.8Mg-5.2Si alloys were fabricated by centrifugal casting using heated permanent mold. These composites consist of three layers: inner layer segregates lots of blocky primary Mg2Si and a litter blocky primary Si, middle layer contains without primary Mg2Si and primary Si, outer layer contains primary Mg2Si and primary Si. The position, quantity and distribution of primary Mg2Si and primary Si in the composites are determined jointly by alloy composition, solidification velocity under the effect of centrifugal force and their floating velocity inward. Na salt modifier can refine grain and primary Mg2Si and make primary Mg2Si distribute more evenly and make primary Si nodular. For centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy, the microstructures of inner layer, middle layer and outer layer are almost similar, single layer materials without primary Mg2Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing

  19. Variación antropométrica y nutricional en Susques y Alto Comedero entre 2002-2007

    Bejarano, Ignacio

    2007-01-01

    Full Text Available Las poblaciones humanas experimentan variaciones de los parámetros antropométricos como expresión de los cambios socioambientales. El objetivo de este trabajo fue analizar la variación temporal de talla, peso y estado nutricional en dos poblaciones jujeñas situadas a distintos niveles altitudinales. Los datos procedieron de mediciones realizadas en 2002 y 2007 en poblaciones de 6 a 17 años de Susques (3500 m y Alto Comedero (1200 m. Se calcularon las categorías nutricionales de Waterlow y las diferencias entre talla y peso y categorías nutricionales se establecieron con ANOVA y prueba de comparación de proporciones (χ2 respectivamente. Para ambas poblaciones se observaron diferencias interanuales estadísticamente significativas de los promedios de talla y peso, siendo menores en Susques en el 2007, lo contrario sucede en Alto Comedero. Las diferencias interanuales de la categorías nutricionales no fueron estadísticamente significativas en Alto Comedero, pero si en Susques para normonutridos y obesos que disminuyeron y aumentaron respectivamente entre 2002 y 2007. En el contexto de las modificaciones socioeconómicas experimentadas por la población susqueña en los últimos años, debido a su mayor conexión e integración con poblaciones vecinas por la apertura del Paso de Jama, los resultados indicarían un empeoramiento de las condiciones nutricionales de su población infanto juvenil.

  20. La relación entre la capacidad de atencion dividida y la estimación prospectiva del tiempo

    Susana Celeste Azzollini

    2004-01-01

    Full Text Available Se realizó una investigación cuyo objetivo fue determinar si la capacidad de atención dividida resultaba explicativa de la variabilidad de las estimaciones prospectivas del tiempo. Los modelos teóricos sobre dicha estimación postulan que los recursos atencionales de procesamiento están divididos entre un procesador temporal, que cuenta y almacena unidades temporales subjetivas (Subjective Temporal Units - STUs y otras actividades de procesamiento no temporal (Zakay, 1993. Se seleccionó una muestra de 36 estudiantes universitarios que fueron asignados al azar a cada una de las seis condiciones experimentales, determinadas por un diseño factorial 3 x 2, y sus factores básicos fueron: cantidad de tareas y niveles de complejidad del material. Se confeccionaron materiales para las diferentes tareas y otros con el fin de evaluar las aptitudes mnémicas y la capacidad de atención dividida. Se solicitó a los sujetos que mientras realizaban las tareas, detuvieran un cronómetro cuando consideraran que había pasado un período de tiempo predeterminado. La estimación del tiempo se calculó por la diferencia en segundos entre el tiempo real y el tiempo estimado. Los datos se procesaron con análisis de correlación, discriminante y factorial de variancia. Los resultados obtenidos indican que la capacidad de atención dividida se correlaciona con la estimación temporal prospectiva y además, la capacidad de atención dividida resulta un buen predictor de la capacidad estimativa de los sujetos, especialmente de los sobre-estimadores. Las diferencias en las aptitudes mnémicas no explicaron la variabilidad de las estimaciones prospectivas.