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Sample records for acopladas entre si

  1. ACOPLAMIENTO EXCITATORIO E INHIBITORIO DE NEURONAS PULSANTES ACOPLADAS

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    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. Produção de sentidos entre adolescentes sobre o cuidado de si na gravidez

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    Nayara Bueno de Araujo

    2016-06-01

    Full Text Available No pré-natal, profissionais comumente desconsideram a rede de produção de sentidos de adolescentes sobre o cuidado de si na gravidez. Busca-se evidenciá-la em uma situação concreta, com foco nas fontes e comunidades de referência para adolescentes de áreas pobres de Cuiabá-MT, Brasil, sintetizadas em um mapa. Trata-se de estudo qualitativo, realizado entre 2014-2015, com 12 adolescentes grávidas, por meio de: grupo focal, entrevista individual, consulta a prontuários e análise baseada em preceitos e categorias da Análise de Discurso Crítica. A principal comunidade discursiva de referência das adolescentes é a família, embora profissionais de saúde, mídia e conhecidos também intermedeiem a construção de seus discursos. A cultura biomédica e o cuidado, como controle de riscos via comportamentos, são, respectivamente, as fontes e as vozes mais relevantes dentre outras concorrentes. Entender essas peculiaridades propicia ao profissional buscar melhores formas de relacionar-se com adolescentes e ampliar sua autonomia.

  3. RADICALMENTE SANTOS: o rock’n’roll e o underground na produção da pertença religiosa entre jovens

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    Flávia Slompo Pinto

    2016-11-01

    Full Text Available Esse artigo apresenta um estudo realizado entre os jovens da igreja evangélica Crash Church Underground Ministry, fundada em 2006 e localizada em um pequeno galpão do bairro Ipiranga, na cidade de São Paulo. A partir do trabalho de campo, foi possível perceber que a cosmologia pentecostal, acoplada à cena underground do heavy metal, fornece aos jovens meios de pensar as práticas de construção de seus projetos de vida como voltadas para algo de grande valor. Vendo a si próprios como socialmente marginalizados, esses jovens invertem tal condição a partir do underground e da religião, construindo com tais recursos agencialidade e poder, de forma a forjar um estilo próprio de existência.

  4. Aplicación del bioensayo EROD-H4IIE para la determinación de dioxinas en carnes de pollos broiler: un estudio de equivalencia con la cromatografía de gases de alta resolución acoplada a espectrometría de masas de alta resolución

    OpenAIRE

    Schoffer, JT; Bustos-López, C; Sotomayor, P; Mattar, CA; González, A; Robles, C; Samsing, F; Acevedo, O; Valdovinos, CE

    2011-01-01

    En el presente estudio se aplicó el bioensayo EROD con línea celular H4IIE para determinar la equivalencia de resultados para carnes de pollo, entre el bioensayo EROD-H4IIE en pg TCDD-EQ/g de tejido y los resultados de la cromatografía de gases de alta resolución acoplada a espectrometría de alta resolución (HRGC/HRMS) en pg WHO-TEQ/g de grasa. Para lo anterior se utilizaron 41 muestras compuestas de trutros de pollo. Éstas fueron obtenidas en la planta faenadora de 4 planteles diferentes de ...

  5. CONTROLE DE SI, DOR E REPRESENTAÇÃO FEMININA ENTRE LUTADORES(AS DE MIXED MARTIAL ARTS (MMA

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    Samuel Oliveira Thomazini

    2008-12-01

    Full Text Available This papers aims to present results of a seven months ethnographic research in three gyms of Mixed Marcial Arts (MAA, focusing the identity construction of the fighters. Observations and interviews were done, as well as pictures and film takes in traing ans competition were also important. The results suggest the existence of bioidentities processes in sense of selfcontrol and rationalization of pain. The representations of the presence of females is quite ambiguous in this universe of masculinity. La investigación se ocupó de tres gimnasios especializados en Mixed Marcial Arts (MAA, analizando rasgos esenciales de la construcción de las identidades de luchadores y luchadoras. Fueran hecahs durante siete meses observaciones participantes (registradas en diario de campo y entrevistas semi-dirigidas. Fotos y filmages de entrenamientos y competiciones fueran también importantes. Los resultados sugieren la presencia de procesos bioidentitários vinculados al control de si mismo, a la racionalización del dolor y, además, representaciones ambiguas sobre la presencia femenina en este universo que es sobretodo masculino. Trata-se de uma pesquisa realizada em três academias especializadas em Mixed Marcial Arts (MMA. Analisa alguns elementos indispensáveis à forja identitária de lutadores(as desta modalidade. A etnografia durou sete meses, oportunidade para combinar uma observação participante (devidamente registrada no diário de notas com a realização de entrevistas semi-estruturadas com os(as atletas. Fotografias e filmagens dos locais de treinamento e de competição foram recursos metodológicos também úteis. Os resultados indicam a existência de processos bioidentitários vinculados ao controle de si e à racionalização da dor, apontando, além disso, para uma representação ambígua em relação à presença feminina em um universo ainda predominantemente masculino.

  6. Réécritures posthumes de Tchicaya U Tam’si entre Brazzaville et Pointe-Noire

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    Pierre Leroux

    2015-03-01

    Full Text Available L'œuvre théâtrale de l'auteur congolais Tchicaya U Tam'si (1931-1988 se résume à trois textes : Le Zulu, Le Destin glorieux du Maréchal Nnikon-Nniku prince qu'on sort et Le Bal de Ndinga. Cependant, les nombreuses adaptations pour la scène de romans, nouvelles et autres ensembles de poésies témoignent de la volonté qu'ont eue certains artistes congolais ou français de se réapproprier l'héritage du « père de notre rêve ». Au travers de l'examen de trois spectacles montés à Brazzaville et à Pointe-Noire, cet article tente de montrer comment la scène transforme les textes et comment l'auteur lui-même devient un personnage représenté et fantasmé.

  7. O professor que cativa: entre a narrativa da história e o cuidado de si

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    Marcello Paniz Giacomoni

    2016-03-01

    Full Text Available O presente artigo apresenta e discute os primeiros passos da pesquisa “Ensino de História e narrativas: o professor e a persuasão em sala de aula”, desenvolvida no Programa de Pós Graduação de Educação da UFRGS, em nível de doutorado, sob orientação do Prof. Dr. Fernando Seffner. Partindo de uma reflexão sobre o Ensino de História e analisando o caráter narrativo da história, passando por autores como Hayden White, Peter Gay, Jörn Rüsen, Paul Ricoeur, e Walter Benjamin, desejamos compreender quais estratégias são utilizadas pelos professores na construção de suas aulas. Interessa-nos compreender quais elementos narrativos e de estilo compõem um discurso histórico capaz de obter a adesão do auditório escolar, a partir de referenciais da Nova Retórica. Nessa análise, o que propomos é uma arte, relacionando a narrativa com a criação subjetiva e a experiência vivida (no caso, a experiência histórica, compreendendo como os professores de História elaboram o conhecimento historiográfico em suas aulas. Essa elaboração visa a negociar a distância entre o tempo passado e o momento do aluno, gerando momentos de encantamento ao poder da palavra. Ensino de História, professores,narrativas,estilo,nova retórica,

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

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    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%.

  9. Aplicación del bioensayo EROD-H4IIE para la determinación de dioxinas en carnes de pollos broiler: un estudio de equivalencia con la cromatografía de gases de alta resolución acoplada a espectrometría de masas de alta resolución Application of the EROD-H4IIE bioassay for the determination of dioxins in broiler chicken meat: an equivalence study with high resolution gas chromatography coupled to high resolution mass spectrometry

    OpenAIRE

    JT Schoffer; C Bustos-López; P Sotomayor; CA Mattar; A González; C Robles; F Samsing; O Acevedo; CE Valdovinos

    2011-01-01

    En el presente estudio se aplicó el bioensayo EROD con línea celular H4IIE para determinar la equivalencia de resultados para carnes de pollo, entre el bioensayo EROD-H4IIE en pg TCDD-EQ/g de tejido y los resultados de la cromatografía de gases de alta resolución acoplada a espectrometría de alta resolución (HRGC/HRMS) en pg WHO-TEQ/g de grasa. Para lo anterior se utilizaron 41 muestras compuestas de trutros de pollo. Éstas fueron obtenidas en la planta faenadora de 4 planteles diferentes de ...

  10. Reactividad entre whiskers de α-SiC y aluminio durante el procesado por vía líquida de materiales compuestos de matriz metálica

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    Ureña, A.

    1999-06-01

    Full Text Available The reactivity between α-SiC whiskers and an aluminium alloy (Al-Cu-Mg, both present in a metal matrix composite, has been studied when such matrix is in molten state. Using mainly transmission electron microscopy (TEM and electron microdiffraction (ED, the nature and morphology of the reaction products generated at the α-SiC/aluminium interface, when this last melts under different condition which simulate casting and welding procedures for metal matrix composites, have been characterised. Both the formation of Al4C3 aggregates with platelet morphology generated by dissolution-reaction mechanisms, and aciculate crystals of the same carbide form by complete dissolution of the α-SiC whiskers and later Al4C3 precipitation into the molten aluminium. Ternary Al-Si carbides with high chemical stability have been also identified by TEMED (β-Al4SiC4, being its formation related with higher energetic conditions than for the Al4C3.

    Se realiza un estudio de la reactividad entre whiskers de α-SiC y una aleación de aluminio en estado líquido (Al-Cu-Mg, que forman parte de un material compuesto de matriz metálica. Empleando fundamentalmente técnicas de microscopía electrónica de barrido (MEB y de transmisión (MET, junto con difracción de electrones (DE, se ha caracterizado la naturaleza y morfología de los productos de reacción que se generan en la intercara α-SiC/aluminio, cuando éste funde en diferentes condiciones que simulan procesos de fabricación y soldadura del material compuesto. Se ha observado tanto la formación de agregados de Al4C3 con morfología tabular producidos por mecanismos de disolución-reacción de los whiskers, como de cristales aciculares del mismo tipo de carburo formados por disolución total de α-SiC y precipitación en el aluminio fundido. Se ha determinado también que, en condiciones suficientemente energéticas, pueden llegar a formarse carburos ternarios de aluminio y silicio (β-Al4SiC4 que

  11. 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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

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    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. 

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

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    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.

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

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    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.

  15. Determinação de compostos nitrogenados aromáticos em alcatrão de carvão através da cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas

    OpenAIRE

    Juliana Macedo da Silva

    2014-01-01

    A cromatografia gasosa bidimensional abrangente (GC×GC) é uma excelente técnica analítica para a determinação de diversos compostos em matrizes complexas, como é o caso do alcatrão de carvão, objeto deste estudo. O alcatrão foi obtido através do processo de pirólise e submetido à análise por GC×GC visando a especiação de compostos nitrogenados aromáticos. A GC×GC acoplada à espectrometria de massas com analisadores do tipo quadrupolar (qMS) e por tempo de voo (TOFMS) foram utilizados para a d...

  16. Entre clémence et extrême sévérité. Les juges de la Haute Cour de Namur face aux femmes criminelles dans la seconde moitié du XVIIIe siècle.

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    Sarah Auspert

    2010-07-01

    Full Text Available Au XVIIIe siècle, une nouvelle conception de la femme, développée par les esprits des Lumières, tend à se diffuser dans la société. Au discours religieux qui diabolisait les représentantes du « sexe faible », se substitue progressivement une image plus positive de la femme fondée sur ses fonctions « naturelles » d’épouse et de mère. À travers l’analyse de la répression de la criminalité féminine exercée par la Haute Cour de Namur dans la seconde moitié du XVIIIe siècle, notre mémoire de maîtr...

  17. Entre/Plantas

    OpenAIRE

    Montoro Coso, Ricardo; Sonntag, Franca Alexandra

    2014-01-01

    La palabra Inter-és proviene etimológicamente de las palabras latinas inter y esse; y significa “lo que está-entre dos o más personas, o sea lo que las une pero también las separa”. Los prefijos inter- y entre-, en la mayor parte de los casos, describen estados o acciones ambiguas de los términos que preceden. De esta operación aditiva surgen maclas de vocablos; el inter-sticio como la “hendidura o espacio que media entre dos cuerpos o entre dos partes de un mismo cuerpo”; y así sucesivamente...

  18. (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

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    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

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

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    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?

  20. Arquitectura de acoplamiento entre INS/GPS para navegación precisa en trayectorias establecidas

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    Monica Zabala

    2018-05-01

    Full Text Available Se implementa un prototipo basado en tarjetas de desarrollo para el acoplamiento del sistema de navegación inercial con GPS para mejorar la precisión en la navegación sobre una trayectoria. Inicialmente es necesario la calibración de la unidad de medición inercial (IMU mediante un filtro de MADGWICK para que los datos brutos extraídos sean fiables, el acoplamiento de las señales del sistema de posicionamiento global (GPS e IMU se realiza a través de la arquitectura Tight Coupling por medio del Filtro de Kalman con el fin de eliminar errores correlacionados entre sistemas y alcanzar mejor precisión en la solución de navegación generalmente utilizada para aplicaciones en vehículos aéreos no tripulados (UAV. Se desarrolla la aplicación final denominada LJLAB en Matlab, cuya función es procesar y visualizar los datos medidos de ambos sistemas en forma independiente y acopladas al mostrar gráficamente el error en la precisión de posicionamiento que existe entre tecnologías, lo cual es comprobado estadísticamente a través del método experimental ANOVA que calcula el error absoluto entre los puntos reales y los medidos a través del análisis de la media y varianza de los datos observados.

  1. 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

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    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

  2. SI Notes.

    Science.gov (United States)

    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)

  3. REPENSANDO LAS RELACIONES ENTRE LA EDUCACIÓN Y EL TRABAJO: Una reflexión basada en investigaciones realizadas en México

    Directory of Open Access Journals (Sweden)

    María de Ibarrola

    Full Text Available Con base en investigaciones realizadas en México por la autora desde la década de los ochenta, se han ido construyendo cuatro dimensiones de análisis necesarias para repensar la naturaleza y el alcance de las relaciones entre la educación y el trabajo, más allá de las teorías clásicas. Se trata de la estructura heterogénea y desigual de los espacios de trabajo en el país; la prioridad que las políticas públicas conceden a la formación escolar para el trabajo y los actores que participan en ello; las condiciones reales de la formación para el trabajo en las escuelas; y las transiciones y trayectorias que viven los individuos entre la escuela y el trabajo. Con base en esos análisis se plantea la noción de relaciones complejas, multidimensionales, cambiantes, contradictorias, interactivas e históricas, flojamente acopladas, entre las que suceden todo tipo de imperfecciones y desajustes.

  4. Percepções sobre cuidar de si, promoção da saúde e sobrepeso entre acadêmicos de enfermagem Percepciones sobre el cuidado de si mismo, promoción de la salud y sobrepeso en estudiantes de enfermería Perceptions of Self-care, health promotion and overweight among nursing students

    Directory of Open Access Journals (Sweden)

    Luciara Fabiane Sebold

    2011-09-01

    Full Text Available Pesquisa qualitativa, Convergente Assistencial (PCA, desenvolvida com 42 acadêmicos de enfermagem, em uma Universidade Pública da Região Sul do Brasil. Objetivou identificar as percepções dos acadêmicos de enfermagem sobre o cuidar de si, para a promoção da saúde e a evitabilidade do sobrepeso. A coleta dos dados deu-se durante quatro encontros, através de dinâmicas de grupo, confecções de cartazes, atividades lúdicas, utilização de instrumento. A análise dos dados seguiu PCA. Categorias: Atividades físicas; Alimentação saudável; Ambiente familiar; Autoestima e autoimagem. Resultados: Os acadêmicos reconhecem a importância de Cuidar de Si; apresentam conhecimento e relacionam à temática; percebem o Cuidar de Si como forma de manter peso e/ou buscar peso adequado. As contribuições estão no sentido de novas reflexões sobre a realidade dos acadêmicos, e subsídios para inovação do ensino e aprendizagem, sensibilização dos futuros profissionais da área.Investigación cualitativa, Convergente Asistencial (PCA, desarrollada con 42 estudiantes de enfermería en una universidad pública en el sur de Brasil. El objetivo fue identificar las percepciones de los estudiantes de enfermería sobre el cuidado consigo mismo, para promover la salud y prevenir el sobrepeso. La recopilación de datos tuvo lugar durante cuatro sesiones: a través de dinámicas de grupo, de la producción de carteles, de actividades lúdicas, del uso de instrumentos. El análisis de datos siguió PCA. Categorías: actividades físicas, alimentación saludable, ambiente familiar, autoestima y autoimagen. Resultados: los académicos reconocen la importancia de cuidar de si mismos; presentan conocimientos y los relacionan con el tema; perciben el Cuidar de Si mismo como una manera de mantener el peso y / o buscar un peso adecuado. Las contribuciones son a un nuevo pensamiento sobre la realidad de los estudiantes, y subvenciones para la enseñanza y

  5. Interacciones entre plantas y microorganismos del suelo: Consecuencias para la dinámica de comunidades vegetales

    OpenAIRE

    Lozano Bernal, Yudi M.

    2014-01-01

    En esta tesis doctoral pretendemos aclarar aspectos fundamentales relacionados con la interacción entre plantas y microorganismos del suelo y sus consecuencias para la dinámica de las comunidades vegetales. Pretendemos comprobar si las comunidades microbianas están determinando interacciones negativas y/o positivas entre plantas; si tras el abandono de tierras dedicadas al cultivo, las plantas y los microorganismos del suelo siguen patrones sucesionales, y si los microorganismo...

  6. Relation entre l’environnement politique et économique et la production architecturale dans la ville de Dubrovnik aux XVIIème et XVIIIème siècles / The relationship between the political and economic context and the architecture in Dubrovnik during the 17th and 18th Centuries

    Directory of Open Access Journals (Sweden)

    Anita Ruso

    2014-06-01

    Full Text Available Durant les debuts dé la période moderne, Dubrovnik (Ragusa en latine, une ville entre l'Orient et l'Occident, fonda sa richesse sur le commerce. Malgré sa position géographique favorable, la ville se situe dans une zone sismique complexe. Le grand séisme qui ravagea Raguse en 1667 tua environ 2000 de ses habitants et détruisit un grand nombre de bâtiments. Cet article porte sur les relations entre la production artistique et l’environnement économique dans la ville de Dubrovnik après le grand séisme qui fournit l’occasion de procéder à une rénovation architecturale de grand envergure. Jusqu'à présent, la vaste bibliographie pourtant sur ce sujet n’a pas encore mis l'accent sur ce rapport. La question se pose de savoir combien et comment furent payés les architectes qu’y vénèrent à l’instigation d'ambassadeurs et d'agents commerciaux ragusain. En outre l’article cherche à éclairer la situation économique de Dubrovnik à partir du milieu du 17ème jusqu'au début du 18ème siècle.   During the Early Modern period, Dubrovnik (Latin Ragusa managed to benefit from its geographical position between the East and the West, making trade the base of its wealth.  Unfortunately, the city was also in the zone subject to seismic activity, and the strong earthquake that struck the city in 1667 killed around 2000 people and physically damaged most of its architecture. Therefore, this article discusses the relationship between artistic production and the economic environment in the city of Dubrovnik after 1667. The consequences of the so called “Great Earthquake” have been partially investigated in terms of importation of architectural projects and architects, but there is no scholarly work on the economy of rebuilding of the city on the periphery of catholic Europe. The article includes a list of repaired and rebuilt architecture as well as information about the payments for it and the general economic situation in

  7. Endostatin (EntreMed).

    Science.gov (United States)

    Grosios, K

    2000-07-01

    EntreMed has licensed the worldwide rights to the angiogenesis inhibitor Endostatin, a 20 kDa C-terminal fragment of collagen XVIII, from the Children's Hospital of Boston, a teaching affiliate of Harvard Medical School. It is being developed as a potential cancer treatment and may also be useful in certain types of blindness and arthritis [227427]. EntreMed filed an IND for Endostatin in June 1999 [334125] and as of September 1999, phase I trials were underway [341462]. As of April 2000, the company had initiated plans for testing low doses of Endostatin in cancer patients using continuous infusion and sc administration in a further phase I study to be conducted in Europe [361594]. A phase I trial of Endostatin which will evaluate the safety and efficacy of Endostatin at a range of doses in no more than 100 cancer patients has been initiated. The trial will take place at the University of Texas MD Anderson Medical Center and the University of Wisconsin Cancer Center in Madison. The National Cancer Center will be sponsoring the trial, which is expected to be completed in late 2000. As of March 2000, there had been no serious adverse events attributable to Endostatin administration. The first report from this trial is expected in autumn 2000 [341462], [366312]. The mechanism of action for Endostatin remains unclear, although reports from the 91st AACR Meeting in April 2000 showed that recombinant human endostatin bound to a number of tropomyosin cDNAs in a library screen [362039]. In preclinical studies, repeated administration of Endostatin consistently shrank primary tumors and did not produce any drug resistance. In mice, a variety of tumors which had progressed to 1 to 2% of total body weight, regressed to microscopic, dormant lesions following Endostatin treatment [231418], [231470], [270673]. Types of cancers which respond to Endostatin include lung, skin, vascular and fibrosarcomas. Toxicology studies in cynomolgus monkeys showed that bolus injections of

  8. Desempenho de modelos de calibração de guias de onda acopladas a TDR e a multiplexadores em três tipos de solos Performance of calibration models for TDR and multiplexer - connected waveguides in three soil types

    Directory of Open Access Journals (Sweden)

    Eugenio Ferreira Coelho

    2006-02-01

    Full Text Available O trabalho teve como objetivo avaliar modelos de calibração para dois tipos de guias de onda de TDR, referentes a dois equipamentos (Trase System e TDR 100, acopladas diretamente ao analisador de umidade ou a multiplexadores. Amostras de três tipos de solo foram acondicionadas em segmentos de tubos de PVC e saturadas. Dois tipos de guias de onda de três hastes, com capacitor e com resistor foram inseridas dentro de cada segmento de tubo com solo e conectadas a dois equipamentos de TDR, diretamente no testador de cabos ou via multiplexadores. Dados de umidade obtidos por gravimetria e da constante dielétrica foram tomados em cada coluna durante a secagem do solo da saturação até umidades próximas do limite inferior de disponibilidade de água por meio de leituras com as guias de onda conectadas ao testador de cabos e conectadas ao multiplexador. Um modelo polinomial cúbico foi ajustado aos dados da constante dielétrica do solo (épsilon e da correspondente umidade (teta e cinco modelos de determinação de q em função de e foram testados quanto ao desempenho. Os resultados mostraram que não houve diferença significativa na calibração das guias de onda com capacitor para uso com a TDR Trase System, considerando a conexão das guias ao analisador de umidade ou a multiplexadores. No caso da TDR 100, as guias de onda com resistor devem ser calibradas conforme o seu uso. O modelo cúbico foi o de melhor desempenho seguido pelo modelo de Roth que estimou, com boa exatidão, os valores da constante dielétrica e da umidade com a mais próximo de 0,5 para as guias de onda com capacitor que com as guias com resistor.The study aimed at evaluating of calibration models for two kinds of TDR waveguides used with Trase System and TDR 100 equipments linked to the cable tester or the multiplexer. Disturbed samples of three soils were packed in PVC columns and, after soil saturation, two TDR waveguides of three rods with capacitor and with

  9. 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.

    Directory of Open Access Journals (Sweden)

    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

  10. Entre monos y centauros

    Directory of Open Access Journals (Sweden)

    Serge Gruzinski

    2005-02-01

    Full Text Available    ¿Qué relación puede existir entre Ovidio, Tiziano y unos tlacuilo indios de la sierra otomí ? ¿Qué tienen en comun  el pintor mas famoso del siglo XVI , el veneciano Tiziano (+ 1576,  un poeta latino del primer siglo despues de Cristo, Publio Ovidio Nasón (-43/17 ,  y unos artistas indígenas anónimos del pueblo otomi de Ixmiquilpan?   Aunque la reunión de estos tres nombres parezca extraña y sorprendente, los hilos que los unen no son nada anecdóticos.  Permiten entender mejor la manera...

  11. Entre formigas e estrelas

    Directory of Open Access Journals (Sweden)

    Vinicius Prates

    2013-06-01

    Full Text Available Esta resenha apresenta o livro Reagregando o social: uma introdução à teoria do ator-rede, última obra do filósofo francês Bruno Latour publicada no Brasil. Nele, o autor se propõe a elaborar uma suma da crítica que faz aos conceitos usualmente aceitos de “social”, o que vem desenvolvendo ao longo dos últimos anos de produção intelectual. Neste processo ele criou a “Teoria-ator-rede”, que busca reestabelecer teoricamente as relações entre o que chama de mediadores “humanos” e “não-humanos”.

  12. Entre grafos y bits

    Directory of Open Access Journals (Sweden)

    Carla Boserman

    2014-02-01

    Full Text Available Este texto se propone ahondar en las intersecciones de lo analógico y lo digital, en el encuentro de la baja y la alta tecnología. Tomando consciencia de la materialidad de ambas esferas para pensar desde ahí en objetos, prácticas de dibujo y documentación que puedan aportar otras formulaciones aplicables a métodos de investigación. Entre grafos y bits, diseccionaremos un objeto, el #relatograma, analizaremos su ecología y propondremos una reflexión acerca de su condición digital que genera paisajes por agregación #coreograma, explorando así su capacidad de ser reporte y aporte cognitivo. Between graphs and bits  Abstract This paper delves into the intersections of analogue and digital cultures, at the points at which low and high technology converge. While acknowledging the materiality of these two spheres, I aim to produce an enquiry into objects, drawings and documentation practices that can contribute to developing new research methods. Among graphs and bits, I will dissect one object: the #relatograma, in order to analyze its ecology and propose a critical reflection on its digital condition and its ability to produce aggregated landscapes, or what I define as #coreograma. I will thereby explore its ability to be share information and produce knowledge. Keywords: Material culture; research methods; digital objects; drawing; #relatograma.

  13. Las relaciones de comercio e inversión entre Colombia y Venezuela

    OpenAIRE

    Eglé Iturbe de Blanco

    1997-01-01

    Venezuela y Colombia cuentan con una larga trayectoria histórica en sus relaciones económicas. Comercian entre ellas y sus nacionales a lo largo de la frontera desde su nacimiento como naciones e interactúan entre ambos países como si fuera uno solo. Al norte, en la península de la Guajira, viven poblaciones indígenas comunes cuyo sustento es el comercio entre ambos lados de la frontera; y al sur, en los estados andinos venezolanos limítrofes con los llanos colombianos, tradicionalmente se ha...

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

    DEFF Research Database (Denmark)

    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....

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

    Directory of Open Access Journals (Sweden)

    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.

  16. El periodista, entre el Poder

    Directory of Open Access Journals (Sweden)

    JL Dader

    2014-10-01

    Full Text Available El periodismo se debate, desde sus orígenes, entre la reproducción servil de versiones interesadas o la distorsión de propio cuño, por conocimiento insuficiente de una realidad que sólo puede entrever. Los poderes que amenazan la independencia periodística no han hecho más que crecer o aumentar su habilidad con el paso del tiempo. Surgido como ‘oficio de esclavos’ en la época romana, muchos indicadores actuales parecen retornarle al punto de partida: relaciones públicas estratégicas a gran escala, auge de los ‘spin doctors’, extorsión descarnada en las democracias más débiles y populismo de las redes sociales, entre otros. Todo ello, unido o alentado por la degradación interna y el desaliento de la propia institución periodística incapaz de distanciarse de todas esas fuerzas. Su respuesta no puede ser de alianza o competencia con los poderes que la circundan, sino de hábil distanciamiento para moverse entre todos ellos sin dejar de ejercer la vigilancia que los ciudadanos siguen necesitando de su ejercicio profesional.

  17. Effets Josephson generalises entre antiferroaimants et entre supraconducteurs antiferromagnetiques

    Science.gov (United States)

    Chasse, Dominique

    L'effet Josephson est generalement presente comme le resultat de l'effet tunnel coherent de paires de Cooper a travers une jonction tunnel entre deux supraconducteurs, mais il est possible de l'expliquer dans un contexte plus general. Par exemple, Esposito & al. ont recemment demontre que l'effet Josephson DC peut etre decrit a l'aide du boson pseudo-Goldstone de deux systemes couples brisant chacun la symetrie abelienne U(1). Puisque cette description se generalise de facon naturelle a des brisures de symetries continues non-abeliennes, l'equivalent de l'effet Josephson devrait donc exister pour des types d'ordre a longue portee differents de la supraconductivite. Le cas de deux ferroaimants itinerants (brisure de symetrie 0(3)) couples a travers une jonction tunnel a deja ete traite dans la litterature Afin de mettre en evidence la generalite du phenomene et dans le but de faire des predictions a partir d'un modele realiste, nous etudions le cas d'une jonction tunnel entre deux antiferroaimants itinerants. En adoptant une approche Similaire a celle d'Ambegaokar & Baratoff pour une jonction Josephson, nous trouvons un courant d'aimantation alternee a travers la jonction qui est proportionnel a sG x sD ou fG et sD sont les vecteurs de Neel de part et d'autre de la jonction. La fonction sinus caracteristique du courant Josephson standard est donc remplacee.ici par un produit vectoriel. Nous montrons que, d'un point de vue microscopique, ce phenomene resulte de l'effet tunnel coherent de paires particule-trou de spin 1 et de vecteur d'onde net egal au vecteur d'onde antiferromagnetique Q. Nous trouvons egalement la dependance en temperature de l'analogue du courant critique. En presence d'un champ magnetique externe, nous obtenons l'analogue de l'effet Josephson AC et la description complete que nous en donnons s'applique aussi au cas d'une jonction tunnel entre ferroaimants (dans ce dernier cas, les traitements anterieurs de cet effet AC s'averent incomplets). Nous

  18. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  19. 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

    Directory of Open Access Journals (Sweden)

    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.

  20. L’esprit de la chair. Images de la sainteté féminine entre Rhône et Alpes au XVe siècle, thèse de doctorat en histoire médiévale sous la direction Marie-Anne Polo de Beaulieu, EHESS, 2011

    Directory of Open Access Journals (Sweden)

    Anne Doustaly

    2012-05-01

    Full Text Available Dans un espace provençal compris au sens large, du Rhône aux Alpes et de la Méditerranée à la haute Durance, la thèse interroge les choix opérés parmi le sanctoral féminin par les prescripteurs des nombreuses peintures publiques – retables et peintures murales –, les confronte aux cultes, pèlerinages, croyances et à d’autres media promoteurs des saintes –hagiographie, exempla. L’analyse des images et des prix-faits révèle des connivences culturelles entre les commanditaires et les peintres, e...

  1. La Vocación entre los Aspirantes a Maestro

    Directory of Open Access Journals (Sweden)

    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

  2. Causalidade entre as principais bolsas de valores do mundo

    Directory of Open Access Journals (Sweden)

    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.

  3. Nexos estratégicos entre la retórica y la publicidad

    Directory of Open Access Journals (Sweden)

    Luis Gallardo Vera

    2011-06-01

    Full Text Available El presente artículo contribuye a establecer nexos estratégicos entre la retórica y la publicidad. La adopción del prisma estratégico en los estudios retóricos de la publicidad no es común, sin embargo, la relación entre retórica y publicidad a un nivel estratégico es evidente, teniendo presente los estudios que han investigado la simbiosis entre las dos actividades.Del universo compuesto por las investigaciones sobre retórica y publicidad se seleccionó una muestra de las obras susceptibles de responder a la pregunta de cuáles son los nexos estratégicos entre la retórica y la publicidad. Con este criterio se conformó una muestra teóricamente conducida del universo. La hipótesis de partida ha sido que, si existen documentos que indaguen en la relación entre la retórica y la publicidad, es posible construir un documento que muestre de un modo amplio cuáles son los nexos estratégicos entre ambas actividades. Finalmente, se contrastó que, efectivamente, este documento es único al mostrar ampliamente cuáles son los nexos estratégicos existentes entre la retórica y la publicidad.

  4. Luminescence and paramagnetic centers in antigorite and Lizardite, two members of serpentine group: a comparative study;Estudo comparativo entre as propriedades dos centros luminescentes e paramagneticos da antigorita e da lizardita do grupo da SERPENTINA: Mg{sub 3} [Si{sub 2}O{sub 5}] (OH){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, Rene Rojas, E-mail: renerr@usp.b

    2008-07-01

    In this work, we are describing crystals luminescent properties of Antigorite (monoclinic, Mg{sub 3-x}[Si{sub 2}O{sub 5}](OH){sub 4-2x}) and Lizardite (triclinic, Mg{sub 3}[(Si,Fe){sub 2}O{sub 5}](OH){sub 4}). They were studied simultaneously applying several techniques, like: Thermoluminescence (TL), Optical Absorption (OA), Electron Paramagnetic Resonance (EPR), X-rays diffraction and Inductively Coupled Plasma (ICP). Using cold pressed elements and heating the samples to 350 deg C for TL measurements, we can observe reproductive peaks. Antigorita show well differentiated peaks and intensities, but Lizardite show overlapped and similar intensity peaks. Peaks of both samples occur around 150, 200, 250, 300 deg C, and all them grow linearly up to 2 kGy, saturating for high doses, except 250 deg C peak which continue growing with dose until 172 kGy. TL peaks trap parameters and lifetimes were calculated, the curves were fitted using the GCD method with second order kinetic. The EPR spectrum shows 6 hyperfine structure lines, characteristic of Manganese, besides lines due to Iron. It was possible also to observe two super hyperfine Mn{sup 2+} lines. The EPR signal does not change with irradiation dose in both crystals. These impurities were also detected in the ICP analysis. The OA spectrum of lizardite show bands from 370 to 470 nm which were not observed in antigorite samples probably related to Fe{sup 3+} and Mn{sup 2+}. In the infrared region several (OA) bands of Mg-OH combination were observed. Again the OA spectrum of these crystals does not change with irradiation dose. We conclude that TL samples peaks around 150, 200, 250, 300 deg C can be used for radiation ionizing dosimetry (y-rays and B- particle) for intermediate and high doses. (author)

  5. Violencia contra mujeres embarazadas entre las usuarias del Instituto Mexicano del Seguro Social: un estudio sobre determinantes, prevalencia y severidad

    OpenAIRE

    Roberto Castro; Gregorio Agustín Ruiz; María de la Luz Arenas Monreal; Sergio Juárez Márquez; Nora Barrios Martínez Rojas

    2002-01-01

    Se presentan los resultados de una encuesta entre 446 mujeres usuarias de los servicios de salud del Instituto Mexicano del Seguro Social (IMSS) en Morelos, que se encontraban en su tercer trimestre de embarazo. El objetivo era indagar si la violencia contra mujeres se incrementa durante el embarazo o si, por el contrario, disminuye. Se encontró que la prevalencia no varió en ambos periodos (aproximadamente 15 por ciento, en general). En cambio, la severidad de l...

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

    OpenAIRE

    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...

  7. El “consentimiento” negociado entre dos comunidades mineras mexicanas y las trasnacionales Goldcorp y Ternium

    OpenAIRE

    Blanca Ruth Santos Cordero; Eleocadio Martínez Silva

    2015-01-01

    En este artículo se busca reconstruir la dinámica de la relación entre empresas trasnacionales y comunidades rurales mexicanas, a partir de dos estudios de caso: la minera canadiense Goldcorp, en Mazapil, Zacatecas, y la italo-argentina Ternium, en San Miguel Arcángel, en Aquila, Michoacán. La hipótesis sostiene que la racionalidad de la máxima ganancia y el cálculo del riesgo están presentes en las negociaciones entabladas entre las comunidades campesinas y las corporaciones. Y, si bien e...

  8. Las relaciones entre España y Japón

    OpenAIRE

    Jensana, Amadeo

    2013-01-01

    Si bien España y Japón son dos países separados por más de 10.000 kilómetros existe una importante afinidad cultural entre ambos pueblos. Los japoneses admiran muchas de las manifestaciones culturales españolas, entre las que destacan la arquitectura (especialmente el Modernismo catalán), el flamenco, la gastronomía o el deporte (hay numerosos seguidores de la Liga Profesional de Fútbol). Por su parte, los españoles son plenamente conscientes del nivel tecnológico de las grandes corporacio...

  9. Realidad de maltrato en las relaciones afectivas entre jóvenes mexicanos durante el noviazgo

    OpenAIRE

    Cortés Ayala, Lourdes

    2016-01-01

    El objetivo de esta Tesis Doctoral fue estudiar la prevalencia de violencia en el noviazgo en jovenes mexicanos a traves de cuatro estudios. El objetivo del primer estudio ex post facto fue establecer la autopercepción de maltrato, así como los sentimientos de miedo y atrapado que existen entre los miembros de una relación de pareja, y determinar si hay diferencias en la prevalencia de los diferentes tipos de violencia o victimización entre los que se perciben maltratados y los que no, tenien...

  10. La retractación arbitraria, entre principios y remedios

    Directory of Open Access Journals (Sweden)

    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

  11. SI units in radiology

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, P S [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

    1978-11-01

    The proposal of the International Commission on Radiation Units and Measurements that the special units of radiation and radioactivity-roentgen, rad, rem and curie-be replaced by the International System (SI) of Units has been accepted by international bodies. This paper reviews the resons for introducing the new units and their features. The relation between the special units and the corresponding SI units is discussed with examples. In spite of anticipated difficulties, the commission recommends a smooth and efficient changeover to the SI units in ten years.

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

    NARCIS (Netherlands)

    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

  13. Entre palabra, escritura e imagen

    Directory of Open Access Journals (Sweden)

    José Sánchez Parga

    2015-01-01

    Full Text Available Plantea el autor que, hace quinientos años, cuando se produjo el encuentro entre la cultura europea y las americanas junto con la conquista y la dominación colonial se instauró un régimen de comunicación en el que se reprodujo una situación de incomunicación y transcomunicaciones hasta ahora existentes. Se refiere el autor también a la violencia verbal y la ley del silencio, a lo que se entiende por mundo andino, a la comunicación como intercambio, la tradición oral-galaxia radial, la dominación gráfica, la Biblia-Gramática- leyes de Indias, Otavalo, quema de papeles, Guamán Poma, el imperialismo de la imagen, destrucción de ídolos, imagen cristiana colonizadora, imperialismo de la imagen, resistencia cultural, importancia de la virgen y el neocolonialismo electrónico.

  14. 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

    Directory of Open Access Journals (Sweden)

    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

  15. 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

    Directory of Open Access Journals (Sweden)

    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

  16. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  17. Microstructure and Mechanical Property of SiCf/SiC and Cf/SiC Composites

    International Nuclear Information System (INIS)

    Lee, S P; Cho, K S; Lee, H U; Lee, J K; Bae, D S; Byun, J H

    2011-01-01

    The mechanical properties of SiC based composites reinforced with different types of fabrics have been investigated, in conjunction with the detailed analyses of their microstructures. The thermal shock properties of SiC f /SiC composites were also examined. All composites showed a dense morphology in the matrix region. Carbon coated PW-SiC f /SiC composites had a good fracture energy, even if their strength was lower than that of PW-C f /SiC composites. SiC f /SiC composites represented a great reduction of flexural strength at the thermal shock temperature difference of 300 deg. C.

  18. Cooperación; altruismo en las relaciones entre aerolíneas

    OpenAIRE

    Fernández Lerate, Elisa M.

    2016-01-01

    El presente estudio se centra en analizar unas determinadas relaciones cooperativas entre compañías aéreas, con la intención de investigar si sacan provecho o no de dichas relaciones. La cooperación entre esas compañías aéreas puede presentar comportamientos más altruistas o más oportunistas. Para centrar el tema del estudio, se van a analizar los acuerdos de códigos compartidos que llevan a cabo entre ellas. Los datos de cooperación a través de código compartido permitirán conocer qué porcen...

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Entre contener y ser contenido

    Directory of Open Access Journals (Sweden)

    Jorge Morales Meneses

    2016-08-01

    Full Text Available El presente artículo propone una nueva manera de entender los elementos comunes en la formación y el hacer del diseño y de la arquitectura, posibilitando un pensar común y un coactuar en diversas escalas de intervención, necesarias para el manejo de la complejidad del paisaje contemporáneo. La convicción de un pensar común entre ambas disciplinas permite explorar un marco filosófico que incluye a pensadores tan trascendentales como Aristóteles, Kant y Heidegger, estableciendo un orden de pensamiento que los relaciona y sitúa. En momentos en que el territorio está siendo visible y negativamente afectado por elementos no pensados o que fueron imaginados separadamente, este artículo propone una mirada que le dé sentido de totalidad a las acciones del diseño y de la arquitectura, como elementos que permanentemente se contienen en otros de diferente escala, pero que siempre están vinculados. Reconocer el paisaje físico y mental, tangible e intangible que contiene al diseño y a la arquitectura contribuirá a establecer un marco de acción donde todos los elementos construidos por el ser humano puedan tener un rol específico y una escala asumida, e intercomprenderse para mejor utilización de los recursos, disminuir el impacto ambiental y contribuir a un orden social mejor interpretado por los objetos, espacios y sus representaciones.

  1. L’approche sociopsychologique de Horkheimer, entre Fromm et Adorno

    Directory of Open Access Journals (Sweden)

    Katia Genel

    2010-08-01

    Full Text Available Le cadre du programme interdisciplinaire de recherche défini par Max Horkheimer dans les années 1930 doit beaucoup à Erich Fromm, qui a introduit la psychologie sociale dans la Théorie critique de la société. Or, une décennie plus tard, Fromm est la cible privilégiée des attaques et sa théorie apparaît désormais comme incompatible avec les positions défendues par Horkheimer et Adorno. Partant de ces tensions qui ont marqué l’histoire de l’École de Francfort, le présent article vise à éclaircir le déplacement qu’elles traduisent sur le plan épistémologique. Si Horkheimer et Fromm partagent des prémisses communes, le premier, dans son travail avec Adorno, se rapproche de manière croissante de la doctrine freudienne alors que le second s’en éloigne. Nous voudrions montrer que l’accord entre Fromm et Horkheimer fut surtout négatif puisqu’il portait sur la critique de Freud : les divergences entre les deux penseurs apparaissent clairement, dès lors qu’on pose en profondeur la question de l’usage de la psychanalyse pour analyser l’un des problèmes centraux de la théorie de la société, l’antagonisme entre individu et société.

  2. Interfacial characterization of CVI-SiC/SiC composites

    International Nuclear Information System (INIS)

    Yang, W.; Kohyama, A.; Noda, T.; Katoh, Y.; Hinoki, T.; Araki, H.; Yu, J.

    2002-01-01

    The mechanical properties of the interfaces of two families of chemical vapor infiltration SiC/SiC composites, advanced Tyranno-SA and Hi-Nicalon fibers reinforced SiC/SiC composites with various carbon and SiC/C interlayers, were investigated by single fiber push-out/push-back tests. Interfacial debonding and fibers sliding mainly occurred adjacent to the first carbon layer on the fibers. The interfacial debonding strengths and frictional stresses for both Tyranno-SA/SiC and Hi-Nicalon/SiC composites were correlated with the first carbon layer thickness. Tyranno-SA/SiC composites exhibited much larger interfacial frictional stresses compared to Hi-Nicalon/SiC composites. This was assumed to be mainly contributed by the rather rough surface of the Tyranno-SA fiber

  3. Sub-barrier fusion of Si+Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

    2017-11-01

    The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  4. Sub-barrier fusion of Si+Si systems

    Directory of Open Access Journals (Sweden)

    Colucci G.

    2017-01-01

    Full Text Available The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3− excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  5. Photoluminescence of Er-doped Si-SiO2 and Al-Si-SiO2 sputtered thin films

    International Nuclear Information System (INIS)

    Rozo, C.; Fonseca, L.F.; Jaque, D.; Sole, J.Garcia

    2008-01-01

    Er-doped Si-SiO 2 and Al-Si-SiO 2 films have been deposited by rf-sputtering being annealed afterwards. Annealing behavior of the Er 3+ : 4 I 13/2 → 4 I 15/2 emission of Er-doped Si-SiO 2 yields a maximum intensity for annealing at 700-800 deg. C. 4 I 13/2 → 4 I 15/2 peak emission for Er-doped Al-Si-SiO 2 at 1525 nm is shifted from that for Er-doped Si-SiO 2 at 1530 nm and the bandwidth increases from 29 to 42 nm. 4 I 13/2 → 4 I 15/2 emission decays present a fast decaying component related to Er ions coupled to Si nanoparticles, defects, or other ions, and a slow decaying component related to isolated Er ions. Excitation wavelength dependence and excitation power dependence for the 4 I 13/2 → 4 I 15/2 emission correspond with energy transfer from Si nanoparticles. Populating of the 4 I 11/2 level in Er-doped Si-SiO 2 involves branching and energy transfer upconversion involving two or more Er ions. Addition of Al reduces the populating of this level to an energy transfer upconversion involving two ions

  6. Les concerts européens à la radio dans l'entre-deux-guerres : mise en ondes d'une métaphore diplomatique

    NARCIS (Netherlands)

    Laborie, L.; Lommers, S.B.

    2008-01-01

    L’expression « concert européen » s’applique à la fois aux relations diplomatiques tissées entre les Etats au xixe siècle et à la diffusion d’émissions musicales à l’échelle continentale entre 1929 et 1939. Au-delà des prouesses techniques, l’ambition culturelle et pacifiste de ces concerts

  7. Utilización de técnicas acopladas de análisis térmico TG-DSC-QMSFTIR en la caracterización de arcillas y composiciones cerámicas utilizadas en la fabricación de baldosas cerámicas. Cuantificación de compuestos de carbono

    Directory of Open Access Journals (Sweden)

    Gómez, M. P.

    2007-10-01

    Full Text Available In this study, a work methodology has been developed for t evolved gas analysis (EGA in clay raw materials and ceramic compositions used in ceramic tile manufacture using coupled thermal analysis techniques (TG-DSC-QMS-FTIR. The different types of gases (CO2, CO, NOx, F, SOx evolving from these raw materials during a thermal cycle up to a peak temperature of 1200ºC were characterised. The possibility of using this calorimeter for the quantification of the CO2 gases evolving from the organic and inorganic carbon (carbonates present in the studied clay materials was also evaluated. The measurements were validated with different reference materials, and the results were compared with those obtained with other analysis techniques, such as thermogravimetry (TG, calcimetry, and coulometry. The thermal analysis technique (TG-DSC-QMS-FTIR is a suitable technique for analysing evolved gases with low uncertainties for carbon compounds quantification. Furthermore, the methodology allows the mineralogical origin identification of the elements present in the evolved gases.

    En el presente estudio se ha desarrollado una metodología de trabajo para el análisis de emisiones gaseosas (EGA en materias primas arcillosas y composiciones cerámicas utilizadas en la fabricación de baldosas cerámicas mediante técnicas acopladas de análisis térmico (TG-DSC-QMS-FTIR. Se caracterizaron los distintos tipos de emisiones (CO2, CO, NOx, F, SOx que se emiten durante un ciclo térmico hasta una temperatura máxima de 1200ºC. Asimismo, se evaluó la posibilidad de la utilización de la técnica para la cuantificación de dichas emisiones. En concreto se ha realizado la cuantificación de emisiones de CO2 procedentes de la presencia de carbono orgánico e inorgánico en materiales arcillosos. Se han validado las medidas con distintos materiales de referencia y se han comparado los resultados con los obtenidos con otras técnicas de análisis, tales como la

  8. SiCloud

    DEFF Research Database (Denmark)

    Jiang, Cathy Y.; Devore, Peter T.S.; Lonappan, Cejo Konuparamban

    2017-01-01

    The silicon photonics industry is projected to be a multibillion dollar industry driven by the growth of data centers. In this work, we present an interactive online tool for silicon photonics. Silicon Photonics Cloud (SiCCloud.org) is an easy to use instructional tool for optical properties...

  9. SI: The Stellar Imager

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2006-01-01

    The ultra-sharp images of the Stellar Imager (SI) will revolutionize our view of many dynamic astrophysical processes: The 0.1 milliarcsec resolution of this deep-space telescope will transform point sources into extended sources, and simple snapshots into spellbinding evolving views. SI s science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI s prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era by imaging a sample of magnetically active stars with enough resolution to map their evolving dynamo patterns and their internal flows. By exploring the Universe at ultra-high resolution, SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magnetohydrodynamically controlled structures and processes in the Universe.

  10. U-Mo/Al-Si interaction: Influence of Si concentration

    International Nuclear Information System (INIS)

    Allenou, J.; Palancher, H.; Iltis, X.; Cornen, M.; Tougait, O.; Tucoulou, R.; Welcomme, E.; Martin, Ph.; Valot, C.; Charollais, F.; Anselmet, M.C.; Lemoine, P.

    2010-01-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 deg. C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 , when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6 Mo 4 Al 43 . For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3 (Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 . On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

  11. Patpong, entre sexe et commerce.

    Directory of Open Access Journals (Sweden)

    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

  12. Nonvolatile field effect transistors based on protons and Si/SiO2Si structures

    International Nuclear Information System (INIS)

    Warren, W.L.; Vanheusden, K.; Fleetwood, D.M.; Schwank, J.R.; Winokur, P.S.; Knoll, M.G.; Devine, R.A.B.

    1997-01-01

    Recently, the authors have demonstrated that annealing Si/SiO 2 /Si structures in a hydrogen containing ambient introduces mobile H + ions into the buried SiO 2 layer. Changes in the H + spatial distribution within the SiO 2 layer were electrically monitored by current-voltage (I-V) measurements. The ability to directly probe reversible protonic motion in Si/SiO 2 /Si structures makes this an exemplar system to explore the physics and chemistry of hydrogen in the technologically relevant Si/SiO 2 structure. In this work, they illustrate that this effect can be used as the basis for a programmable nonvolatile field effect transistor (NVFET) memory that may compete with other Si-based memory devices. The power of this novel device is its simplicity; it is based upon standard Si/SiO 2 /Si technology and forming gas annealing, a common treatment used in integrated circuit processing. They also briefly discuss the effects of radiation on its retention properties

  13. Gd-Ni-Si system

    International Nuclear Information System (INIS)

    Bodak, O.I.; Shvets, A.F.

    1983-01-01

    By X-ray phase analysis method isothermal cross section of phase diagram of the Gd-Ni-Si system at 870 K is studied. The existence of nine previously known compounds (GdNisub(6.72)Sisub(6.28), GdNi 10 Si 2 , GdNi 5 Si 3 , GdNi 4 Si, GdNi 2 Si 2 , GdNiSi 3 , GdNiSi 2 , Gd 3 Ni 6 Si 2 and GdNiSi) is confirmed and three new compounds (GdNisub(0.2)Sisub(1.8), Gdsub(2)Nisub(1-0.8)Sisub(1-1.2), Gd 5 NiSi 4 ) are found. On the base of Gd 2 Si 3 compound up to 0.15 at. Ni fractions, an interstitial solid solution is formed up to 0.25 at Ni fractions dissolution continues of substitution type. The Gd-Ni-Si system is similar to the Y-Ni-Si system

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

    DEFF Research Database (Denmark)

    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...

  15. Oblique roughness replication in strained SiGe/Si multilayers

    NARCIS (Netherlands)

    Holy, V.; Darhuber, A.A.; Stangl, J.; Bauer, G.; Nützel, J.-F.; Abstreiter, G.

    1998-01-01

    The replication of the interface roughness in SiGe/Si multilayers grown on miscut Si(001) substrates has been studied by means of x-ray reflectivity reciprocal space mapping. The interface profiles were found to be highly correlated and the direction of the maximal replication was inclined with

  16. Applications of Si/SiGe heterostructures to CMOS devices

    International Nuclear Information System (INIS)

    Sidek, R.M.

    1999-03-01

    For more than two decades, advances in MOSFETs used in CMOS VLSI applications have been made through scaling to ever smaller dimensions for higher packing density, faster circuit speed and lower power dissipation. As scaling now approaches nanometer regime, the challenge for further scaling becomes greater in terms of technology as well as device reliability. This work presents an alternative approach whereby non-selectively grown Si/SiGe heterostructure system is used to improve device performance or to relax the technological challenge. SiGe is considered to be of great potential because of its promising properties and its compatibility with Si, the present mainstream material in microelectronics. The advantages of introducing strained SiGe in CMOS technology are examined through two types of device structure. A novel structure has been fabricated in which strained SiGe is incorporated in the source/drain of P-MOSFETs. Several advantages of the Si/SiGe source/drain P-MOSFETs over Si devices are experimentally, demonstrated for the first time. These include reduction in off-state leakage and punchthrough susceptibility, degradation of parasitic bipolar transistor (PBT) action, suppression of CMOS latchup and suppression of PBT-induced breakdown. The improvements due to the Si/SiGe heterojunction are supported by numerical simulations. The second device structure makes use of Si/SiGe heterostructure as a buried channel to enhance the hole mobility of P-MOSFETs. The increase in the hole mobility will benefit the circuit speed and device packing density. Novel fabrication processes have been developed to integrate non-selective Si/SiGe MBE layers into self-aligned PMOS and CMOS processes based on Si substrate. Low temperature processes have been employed including the use of low-pressure chemical vapor deposition oxide and plasma anodic oxide. Low field mobilities, μ 0 are extracted from the transfer characteristics, Id-Vg of SiGe channel P-MOSFETs with various Ge

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

    International Nuclear Information System (INIS)

    Kalnitsky, A.; Poindexter, E.H.; Caplan, P.J.

    1990-01-01

    Interface traps due to excess Si introduced into the Si-SiO 2 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-SiO 2 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 SiO 2 . Possible charge trapping mechanisms are discussed and the effect of these traps on MOS transistor characteristics is described using a sheet charge model. (author)

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

    International Nuclear Information System (INIS)

    Warren, W.L.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.; Mathiot, D.; Wilson, I.H.; Xu, J.B.

    1994-01-01

    High-temperature post-oxidation annealing of poly-Si/SiO 2 /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/SiO 2 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 SiO 2 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 (SiO 2 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/SiO 2 /Si systems are all related either directly, or indirectly, to the presence of oxygen vacancies

  19. Strained Si/SiGe MOS transistor model

    Directory of Open Access Journals (Sweden)

    Tatjana Pešić-Brđanin

    2009-06-01

    Full Text Available In this paper we describe a new model of surfacechannel strained-Si/SiGe MOSFET based on the extension of non-quasi-static (NQS circuit model previously derived for bulk-Si devices. Basic equations of the NQS model have been modified to account for the new physical parameters of strained-Si and relaxed-SiGe layers. From the comparisons with measurements, it is shown that a modified NQS MOS including steady-state self heating can accurately predict DC characteristics of Strained Silicon MOSFETs.

  20. Aproximações entre a obra de Júlio Verne e o ensino de física

    OpenAIRE

    Ferreira, Júlio César David [UNESP

    2011-01-01

    Buscamos uma aproximação entre dois campos do conhecimento que envolvem diferentes gêneros de linguagem: a literatura de ficção científica e a física. Partimos do pressuposto de que todo professor é professor de leitura, e como decorrência, todas as formas de leitura se relacionam e criam entre si pontos de apoio para a construção de sentidos. Assim, na obra de Júlio Verne, procuramos por elementos associados ao conteúdo de física do Ensino Médio. Nos livros Viagem ao Centro da Terra, Vinte M...

  1. Os países diferem entre si no acesso a internet?

    OpenAIRE

    Cappellozza, Alexandre; de Moraes, Gustavo Hermínio Salati Marcondes

    2014-01-01

    Este estudo analisou a existência de uma notoriedade comum sobre a audiência de websites em diversos grupos de países com o objetivo de levantar se, independente da variedade de influências endógenas e exógenas que podem interferir na audiência destes portais, há algum padrão de preferência de navegação. Para investigar a popularidade global de websites, este estudo elabora um Índice de Popularidade Virtual – IPV e o aplica com dados utilizados a partir do website Alexa (www.alexa.com) que fo...

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

    KAUST Repository

    Wang, Hsin Ping; Sun, Ke; Noh, Sun Young; Kargar, Alireza; Tsai, Meng Lin; Huang, Ming Yi; Wang, Deli; He, Jr-Hau

    2015-01-01

    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

  3. Irradiation effect on Nite-SiC/SiC composites

    International Nuclear Information System (INIS)

    Hinoki, T.; Choi, Y.B.; Kohyama, A.; Ozawa, K.

    2007-01-01

    Full text of publication follows: Silicon carbide (SiC) and SiC composites are significantly attractive materials for nuclear application in particular due to exceptional low radioactivity, excellent high temperature mechanical properties and chemical stability. Despite of the excellent potential of SiC/SiC composites, the prospect of industrialization has not been clear mainly due to the low productivity and the high material cost. Chemical vapor infiltration (CVI) method can produce the excellent SiC/SiC composites with highly crystalline and excellent mechanical properties. It has been reported that the high purity SiC/SiC composites reinforced with highly crystalline fibers and fabricated by CVI method is very stable to neutron irradiation. However the production cost is high and it is difficult to fabricate thick and dense composites by CVI method. The novel processing called Nano-powder Infiltration and Transient Eutectic Phase (NITE) Processing has been developed based on the liquid phase sintering (LPS) process modification. The NITE processing can achieve both the excellent material quality and the low processing cost. The productivity of the processing is also excellent, and various kinds of shape and size of SiC/SiC composites can be produced by the NITE processing. The NITE processing can form highly crystalline matrix, which is requirement for nuclear application. The objective of this work is to understand irradiation effect of the NITESiC/SiC composites. The SiC/SiC composites used were reinforced with high purity SiC fibers, Tyranno TM SA and fabricated by the NITE method. The NITE-SiC/SiC composite bars and reference monolithic SiC bars fabricated by CVI and NITE were irradiated at up to 1.0 dpa and 600-1000 deg. C at JMTR, Japan. Mechanical properties of non-irradiated and irradiated NITESiC/ SiC composites bars were evaluated by tensile tests. Monolithic SiC bars were evaluated by flexural tests. The fracture surface was examined by SEM. Ultimate

  4. Carbon redistribution and precipitation in high temperature ion-implanted strained Si/SiGe/Si multi-layered structures

    DEFF Research Database (Denmark)

    Gaiduk, Peter; Hansen, John Lundsgaard; Nylandsted Larsen, Arne

    2014-01-01

    Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects.......Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects....

  5. Floridablanca entre la modernidad y la posmodernidad

    OpenAIRE

    Senatore, María Ximena

    2007-01-01

    Este artículo se centra en los diálogos entre el pasado y el presente creados en el marco de la modernidad y de la posmodernidad. La arqueología como práctica social puede ser entendida como un diálogo pasado-presente. Floridablanca es una historia, un sitio, una experiencia, una idea, una utopía. Es también un punto de encuentro entre modernidad y posmodernidad. El objetivo de este trabajo es presentar ciertas reflexiones sobre los diálogos pasado-presente que crean, transforman y reproducen...

  6. El “consentimiento” negociado entre dos comunidades mineras mexicanas y las trasnacionales Goldcorp y Ternium

    Directory of Open Access Journals (Sweden)

    Blanca Ruth Santos Cordero

    2015-01-01

    Full Text Available En este artículo se busca reconstruir la dinámica de la relación entre empresas trasnacionales y comunidades rurales mexicanas, a partir de dos estudios de caso: la minera canadiense Goldcorp, en Mazapil, Zacatecas, y la italo-argentina Ternium, en San Miguel Arcángel, en Aquila, Michoacán. La hipótesis sostiene que la racionalidad de la máxima ganancia y el cálculo del riesgo están presentes en las negociaciones entabladas entre las comunidades campesinas y las corporaciones. Y, si bien en ellas se ha establecido una hegemonía de la racionalidad económica capitalista, el consentimiento ha sido activo y negociado.

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

    OpenAIRE

    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...

  8. Responsabilidad extracontractual y contractual: barrera entre ambas

    Directory of Open Access Journals (Sweden)

    González Hernández, Rut

    2013-01-01

    Full Text Available La finalidad que persigue el sistema de responsabilidad civiles el resarcimiento del daño causado con independencia de que proceda la responsabilidad contractual o la extracontractual, coexistiendo ambas en nuestro ordenamiento jurídico y resultando en ocasiones complicado discernir la frontera entre una y otra.

  9. Synthesis and characterization of laminated Si/SiC composites

    Science.gov (United States)

    Naga, Salma M.; Kenawy, Sayed H.; Awaad, Mohamed; Abd El-Wahab, Hamada S.; Greil, Peter; Abadir, Magdi F.

    2012-01-01

    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. PMID:25685404

  10. Structure of MnSi on SiC(0001)

    Science.gov (United States)

    Meynell, S. A.; Spitzig, A.; Edwards, B.; Robertson, M. D.; Kalliecharan, D.; Kreplak, L.; Monchesky, T. L.

    2016-11-01

    We report on the growth and magnetoresistance of MnSi films grown on SiC(0001) by molecular beam epitaxy. The growth resulted in a textured MnSi(111) film with a predominantly [1 1 ¯0 ] MnSi (111 )∥[11 2 ¯0 ] SiC(0001) epitaxial relationship, as demonstrated by transmission electron microscopy, reflection high energy electron diffraction, and atomic force microscopy. The 500 ∘C temperature required to crystallize the film leads to a dewetting of the MnSi layer. Although the sign of the lattice mismatch suggested the films would be under compressive stress, the films acquire an in-plane tensile strain likely driven by the difference in thermal expansion coefficients between the film and substrate during annealing. As a result, the magnetoresistive response demonstrates that the films possess a hard-axis out-of-plane magnetocrystalline anisotropy.

  11. Synthesis and characterization of laminated Si/SiC composites

    Directory of Open Access Journals (Sweden)

    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.

  12. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

    International Nuclear Information System (INIS)

    Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

    2014-01-01

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN x /SiN y multilayers with high on/off ratio of 10 9 . High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  13. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

    Science.gov (United States)

    Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

    2014-09-01

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiNx/SiNy multilayers with high on/off ratio of 109. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  14. Study of Si/Si, Si/SiO2, and metal-oxide-semiconductor (MOS) using positrons

    International Nuclear Information System (INIS)

    Leung, To Chi.

    1991-01-01

    A variable-energy positron beam is used to study Si/Si, Si/SiO 2 , and metal-oxide-semiconductor (MOS) structures. The capability of depth resolution and the remarkable sensitivity to defects have made the positron annihilation technique a unique tool in detecting open-volume defects in the newly innovated low temperature (300C) molecular-beam-epitaxy (MBE) Si/Si. These two features of the positron beam have further shown its potential role in the study of the Si/SiO 2 . Distinct annihilation characteristics has been observed at the interface and has been studied as a function of the sample growth conditions, annealing (in vacuum), and hydrogen exposure. The MOS structure provides an effective way to study the electrical properties of the Si/SiO 2 interface as a function of applied bias voltage. The annihilation characteristics show a large change as the device condition is changed from accumulation to inversion. The effect of forming gas (FG) anneal is studied using positron annihilation and the result is compared with capacitance-voltage (C-V) measurements. The reduction in the number of interface states is found correlated with the changes in the positron spectra. The present study shows the importance of the positron annihilation technique as a non-contact, non-destructive, and depth-sensitive characterization tool to study the Si-related systems, in particular, the Si/SiO 2 interface which is of crucial importance in semiconductor technology, and fundamental understanding of the defects responsible for degradation of the electrical properties

  15. La relación entre la capacidad de atencion dividida y la estimación prospectiva del tiempo

    OpenAIRE

    Susana Celeste Azzollini; Federico Faustino González; María Emilia Gómez

    2004-01-01

    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...

  16. Importancia de las diferencias entre actividad-procedimiento-proceso para la autoevaluación institucional universitaria

    Directory of Open Access Journals (Sweden)

    Hernando A. Romero

    2002-01-01

    Full Text Available Se refiere en una amplia reflexión, a que tener clara la diferencia de significados entre actividad, procedimiento-proceso, actividad social, proceso social y personal es muy importante en el campo de la autoevaluación institucional porque si no se reconocen sus diferencias, no se puede aludir correctamente lo que se entiende por actividad académica y las diferencias en el proceso pedagógico

  17. Esa Curiosa Relación entre la Medicina y la Literatura

    OpenAIRE

    Pinto Zúñiga, Jorge Ricardo

    2013-01-01

    Si a cualquier persona le preguntaran sí existe alguna relación entre la medicina y la literatura, tal vez piense que no existe tal relación. En este artículo, se analiza a ambas ciencias, aún cuando afirmar que la literatura es una ciencia suene un poco ambiguo. Para el formalismo ruso lo es, ya que el objeto de estudio de la Literatura consiste en el estudio del texto por el texto, es decir, lo literario. Lo literario y la literatura son diferentes: la literatura es todo lo que llamamos a u...

  18. Teoría social: Las relaciones entre Europa y Estados Unidos

    Directory of Open Access Journals (Sweden)

    JOSÉP PICÓ LÓPEZ

    1997-01-01

    Full Text Available la sociologia mundial perderia la comprension de su perspectiva y la variedad de sus enfoques respecto a la realidad social si continua sufriendo la estandarizacion de la sociologia profesional americana. la sociologia europea necesita resistir a esta tendencia de la misma manera en que europa ha de resistir la macdonalizacion de la cultura con el fin de preservar la diversidad de si misma y el mundo. contra esta tesis de r. münch, jeffrey c. alexander cuestiona la forma particular en que el sociologo aleman investiga la dimension social de la ciencia y el reduccionismo de su enfoque, es decir, la asimetria entre las causas sociales y la logica teorica en su analisis de la sociologia europea y americana. este articulo trata de situar, resumir y clarificar algunos de los temas de esta polemica teorica.

  19. Incrementando Las Relaciones Comerciales Entre Colombia Y China

    Directory of Open Access Journals (Sweden)

    Jaime Rafael Ahcar Olmos

    2008-10-01

    Full Text Available Después de las reformas de finales de los años setenta, China consiguió su despegue económico a tal punto que, en la actualidad, se consolida como uno de los mercados más importantes del mundo, recibiendo la atención de investigadores y hombres de negocios a lo largo del planeta. En Colombia existen pocos estudios que hayan explorado las relaciones comerciales con China; en tal sentido, el presente artículo ofrece una amplia revisión de fuentes estadísticas y referencias bibliográficas, dando luces sobre las características y los factores que afectan las relaciones comerciales bilaterales. Los resultados muestran que, si bien China es un valioso proveedor de mercancías para Colombia, las exportaciones hacia ese país aún se encuentran por debajo de su potencial, y se genera un déficit comercial enorme. También muestra que las exportaciones colombianas hacia China se hallan concentradas en unos pocos productos y que dado el tamaño y potencialidad de esta economía, se deberían comenzar negociaciones comerciales que busquen la firma de un acuerdo de libre comercio que permita incrementar el comercio entre ambos países.

  20. Positron annihilation at the Si/SiO2 interface

    International Nuclear Information System (INIS)

    Leung, T.C.; Weinberg, Z.A.; Asoka-Kumar, P.; Nielsen, B.; Rubloff, G.W.; Lynn, K.G.

    1992-01-01

    Variable-energy positron annihilation depth-profiling has been applied to the study of the Si/SiO 2 interface in Al-gate metal-oxide-semiconductor (MOS) structures. For both n- and p-type silicon under conditions of negative gate bias, the positron annihilation S-factor characteristic of the interface (S int ) is substantially modified. Temperature and annealing behavior, combined with known MOS physics, suggest strongly that S int depends directly on holes at interface states or traps at the Si/SiO 2 interface

  1. Formation of Si/Ge/Si heterostructures with quantum dots

    International Nuclear Information System (INIS)

    Zinov'ev, V.A.; Dvurechenskij, A.V.; Novikov, P.L.

    2003-01-01

    It is present the Monte Carlo simulation of epitaxial embedding of faceted three-dimensional Ge islands (quantum dots) in a Si matrix. Under a Si flux these islands expand and undergo a shape change (from pyramidal to drop-like shape). The main expansion occurs at initial stage of embedding in Si (deposition of 1-2 monolayers). This change is controlled by surface diffusion. The shape of island can be preserved when one uses the higher Si fluxes. The reason of island conservation lies in blocking of Ge surface diffusion [ru

  2. 32Si dating of sediments

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2006-01-01

    Useful tools for determining absolute ages of sediments deposited within the last c. 100 years include 210 Pb, 137 Cs, and bomb radiocarbon. Cosmogenic 32 Si, with a half life of c. 140 years, can be applied in the age range 30-1000 years and is ideally suited for this time period. Detection of 32 Si is, however, very difficult due to its extremely low natural specific activity, and the vast excess of stable silicon (i.e. low 32 Si/Si ratio). 23 refs

  3. Relación entre inteligencia emocional y notas de las áreas instrumentales en un grupo de tercero de primaria

    Directory of Open Access Journals (Sweden)

    Vicent Alfaro Mateu

    2016-01-01

    Full Text Available La finalidad de este trabajo es conocer si existe relación entre las áreas instrumentales, lengua y matemáticas, y la Inteligencia emocional de un grupo de alumnos de tercero de primaria de un centro concreto. Participaron 26 alumnos a los cuales se aplicó el instrumento test EQ-­‐i YV de BarOn adaptado para los alumnos. Las técnicas de análisis de correlación a través del SPSS permitirán comprobar si existe o no correlación entre la Inteligencia Emocional de los alumnos, los distintos aspectos de la misma y las áreas instrumentales. En los resultados encontrados no existe correlación entre matemáticas y lengua castellana y el total del cuestionario. La correlación entre las áreas instrumentales, lengua castellana y matemáticas es altamente significativa. Del mismo modo, el total de resultados del cuestionario “E” correlaciona positivamente con las partes del cuestionario “A”, “B”, “C” y “D”, remarcando que hay una alta correlación entre el factor intrapersonal (“B” y el factor de adaptabilidad (“D”. En conclusión, no existe una correlación directa entre las notas de los estudiantes y los resultados del test de inteligencia emocional.

  4. SiC/SiC Cladding Materials Properties Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Mary A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Koyanagi, Takaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Singh, Gyanender P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    When a new class of material is considered for a nuclear core structure, the in-pile performance is usually assessed based on multi-physics modeling in coordination with experiments. This report aims to provide data for the mechanical and physical properties and environmental resistance of silicon carbide (SiC) fiber–reinforced SiC matrix (SiC/SiC) composites for use in modeling for their application as accidenttolerant fuel cladding for light water reactors (LWRs). The properties are specific for tube geometry, although many properties can be predicted from planar specimen data. This report presents various properties, including mechanical properties, thermal properties, chemical stability under normal and offnormal operation conditions, hermeticity, and irradiation resistance. Table S.1 summarizes those properties mainly for nuclear-grade SiC/SiC composites fabricated via chemical vapor infiltration (CVI). While most of the important properties are available, this work found that data for the in-pile hydrothermal corrosion resistance of SiC materials and for thermal properties of tube materials are lacking for evaluation of SiC-based cladding for LWR applications.

  5. Oscillations in the fusion of the Si + Si systems

    International Nuclear Information System (INIS)

    Aguilera R, E.F.; Kolata, J.J.; DeYoung, P.A.; Vega, J.J.

    1986-02-01

    Excitation functions for the yields of all the residual nuclei from the 28 Si + 28,30 and 30 Si + 30 Si reactions have been measured via the γ-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the 28 + 28 Si reaction, we have found evidence for intermediate width structure in the 2α and the αpn channels in 28 Si + 30 Si and for broad structure in the total fusion cross sections for 30 Si + 30 Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)

  6. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Sinergias entre Luxemburgo, ACNUR y Skype

    OpenAIRE

    Bertout, Antoine; Bourcy, Marc de; Faisal, Mohammad

    2011-01-01

    Una reciente asociación estratégica entre ACNUR, el Gobierno de Luxemburgo y el proveedor de software para comunicaciones Skype permite al personal de ACNUR en zonas de condiciones de vida difíciles mantenerse en contacto con sus familiares y amigos. Los socios evalúan de qué forma podría adaptarse la tecnología para otras organizaciones humanitarias.

  8. Tailoring of SiC nanoprecipitates formed in Si

    Energy Technology Data Exchange (ETDEWEB)

    Velisa, G., E-mail: gihan.velisa@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Romania); Trocellier, P. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Vaubaillon, S. [CEA, INSTN, UEPTN, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Miro, S.; Serruys, Y.; Bordas, É. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Meslin, E. [CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191 Gif-sur-Yvette (France); Mylonas, S. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Coulon, P.E. [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA/DSM/IRAMIS-CNRS, 91128 Palaiseau Cedex (France); Leprêtre, F.; Pilz, A.; Beck, L. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

    2013-07-15

    The SiC synthesis through single-beam of C{sup +}, and simultaneous-dual-beam of C{sup +} and Si{sup +} ion implantations into a Si substrate heated at 550 °C has been studied by means of three complementary analytical techniques: nuclear reaction analysis (NRA), Raman, and transmission electron microscopy (TEM). It is shown that a broad distribution of SiC nanoprecipitates is directly formed after simultaneous-dual-beam (520-keV C{sup +} and 890-keV Si{sup +}) and single-beam (520-keV C{sup +}) ion implantations. Their shape appear as spherical (average size ∼4–5 nm) and they are in epitaxial relationship with the silicon matrix.

  9. A desnecessidade do trabalho entre pescadores artesanais

    Directory of Open Access Journals (Sweden)

    Cristiano Wellington Norberto Ramalho

    2015-04-01

    Full Text Available As relações socioculturais e econômicas, entre alguns grupos de pescadores artesanais, não colocam como entes antagônicos trabalho e tempo livre. Do contrário, tais relações celebram aproximações entre saber-fazer pesqueiro, lazer e vida, formando e conformando um todo societário. Inseridos nesse quadro, estão os pescadores artesanais do mar-de-fora da praia de Suape, no município do Cabo de Santo Agostinho, litoral sul de Pernambuco, distante 50 km de Recife. Este artigo busca desvelar a mencionada moral do trabalho e do tempo livre no fazer cotidiano de pescadores dessa Praia, com base na pesquisa etnográfica e na história de vida de 13 pescadores. No geral, identificou-se que há uma moral do trabalho que se confunde à moral do tempo livre, pois o cerceamento de uma delas representa limites à outra. Assim, para esses homens, definir o que é um ser liberto ou cativo liga-se ao encontro indissociável, em termos práticos e simbólicos, entre as referidas morais, o que é essencial para classificar o fazer-se pescador artesanal em seu sentido pleno fundamentado na desnecessidade do trabalho.

  10. SI units in radiation protection

    International Nuclear Information System (INIS)

    Jain, V.K.; Soman, S.D.

    1978-01-01

    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.)

  11. Oscillations in the fusion of the Si + Si systems; Oscilaciones en la fusion de sistemas de Si + Si

    Energy Technology Data Exchange (ETDEWEB)

    Aguilera R, E F; Kolata, J J; DeYoung, P A; Vega, J J [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1986-02-15

    Excitation functions for the yields of all the residual nuclei from the {sup 28} Si + {sup 28,30} and {sup 30} Si + {sup 30} Si reactions have been measured via the {gamma}-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the {sup 28} + {sup 28} Si reaction, we have found evidence for intermediate width structure in the 2{alpha} and the {alpha}pn channels in {sup 28} Si + {sup 30} Si and for broad structure in the total fusion cross sections for {sup 30} Si + {sup 30} Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)

  12. Una coexistencia rítmica para las duraciones (entre Bergson y Deleuze

    Directory of Open Access Journals (Sweden)

    Cristóbal Durán Rojas

    Full Text Available Resumen: La intención del presente artículo es reexaminar el concepto bergsoniano de Duración entendido como coexistencia de niveles de multiplicidad heterogéneos. Si bien dicho concepto ha sido pensado a partir de una comprensión que podría ser caracterizada como continuista, el mismo Bergson evitará confundir dicha continuidad con la idea de homogeneidad. Intentaremos mostrar que la determinación del concepto de Duración se alcanza al definirla como tensión o entrelazamiento entre sucesión y simultaneidad, y por consiguiente, como una multiplicidad que hace coexistir diferentes flujos de duración. Para ello, Bergson propone la existencia de un Tiempo impersonal y único como base para la relación entre duraciones. Nuestra hipótesis es que esta misma situación puede entenderse mejor si se articula el concepto de ritmo en la obra de Deleuze, concepto ligado íntimamente a las nociones de duración y coexistencia. Mediante los movimientos de contracción, dilatación, reunión y división, el ritmo opera junto a las duraciones disponiéndose como un campo de relación, pudiendo ocupar el lugar que había sido asignado al Tiempo único.

  13. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl{sub 2}/Si powder source

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Erchao [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Ueki, Akiko [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Meng, Xiang [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Suzuki, Hiroaki [Graduate School of Engineering, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Itahara, Hiroshi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Tatsuoka, Hirokazu, E-mail: tatsuoka.hirokazu@shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan)

    2016-08-15

    Graphical abstract: Si nanosheets connected to Si nanowires synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst avoid the use of air-sensitive SiH{sub 4} or SiCl{sub 4}. It was evident from these structural features of the nanosheets (leaf blade) with nanowires (petiole) that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes of the Si(111) nanosheets was clearly explained by the interference with the extra diffraction spots that arose due to the reciprocal lattice streaking effect. - Highlights: • New Si nanosheets connected to Si nanowires were synthesized using MnCl{sub 2}/Si powders. • The synthesis method has benefits in terms of avoiding air sensitive SiH{sub 4} or SiCl{sub 4}. • Structural property and electron diffraction of the Si nanosheets were clarified. • Odd lattice fringes of the Si nanosheets observed by HRTEM were clearly explained. - Abstract: Si nanosheets connected to Si nanowires were synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH{sub 4} or SiCl{sub 4}. The existence of the Si nanosheets connected to the Si<111> 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 <211> 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.

  14. Mechanics of patterned helical Si springs on Si substrate.

    Science.gov (United States)

    Liu, D L; Ye, D X; Khan, F; Tang, F; Lim, B K; Picu, R C; Wang, G C; Lu, T M

    2003-12-01

    The elastic response, including the spring constant, of individual Si helical-shape submicron springs, was measured using a tip-cantilever assembly attached to a conventional atomic force microscope. The isolated, four-turn Si springs were fabricated using oblique angle deposition with substrate rotation, also known as the glancing angle deposition, on a templated Si substrate. The response of the structures was modeled using finite elements, and it was shown that the conventional formulae for the spring constant required modifications before they could be used for the loading scheme used in the present experiment.

  15. Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

    2005-08-01

    SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  16. Fabrication and Mechanical Properties of SiCw(p/SiC-Si Composites by Liquid Si Infiltration using Pyrolysed Rice Husks and SiC Powders as Precursors

    Directory of Open Access Journals (Sweden)

    Dan Zhu

    2014-03-01

    Full Text Available Dense silicon carbide (SiC matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w, and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w. The values of flexural strength of the composites initially decreased when 20% (w/w SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w. The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites.

  17. Low-temperature magnetotransport in Si/SiGe heterostructures on 300 mm Si wafers

    Science.gov (United States)

    Scappucci, Giordano; Yeoh, L.; Sabbagh, D.; Sammak, A.; Boter, J.; Droulers, G.; Kalhor, N.; Brousse, D.; Veldhorst, M.; Vandersypen, L. M. K.; Thomas, N.; Roberts, J.; Pillarisetty, R.; Amin, P.; George, H. C.; Singh, K. J.; Clarke, J. S.

    Undoped Si/SiGe heterostructures are a promising material stack for the development of spin qubits in silicon. To deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. Electron mobility and valley splitting are two key electrical metrics of substrate quality relevant for qubits. Here we present low-temperature magnetotransport measurements of strained Si quantum wells with mobilities in excess of 100000 cm2/Vs fabricated on 300 mm wafers within the framework of advanced semiconductor manufacturing. These results are benchmarked against the results obtained in Si quantum wells deposited on 100 mm Si wafers in an academic research environment. To ensure rapid progress in quantum wells quality we have implemented fast feedback loops from materials growth, to heterostructure FET fabrication, and low temperature characterisation. On this topic we will present recent progress in developing a cryogenic platform for high-throughput magnetotransport measurements.

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

    International Nuclear Information System (INIS)

    Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

    2015-01-01

    We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiN x /Si-rich SiN x stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 10 12 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 SiN x films deposited with H 2 dilution show better passivation quality of SiN x /Si-rich SiN x stacked layers than those prepared without H 2 dilution. Effective minority carrier lifetime (τ eff ) in c-Si passivated by SiN x /Si-rich SiN x stacked layers is as high as 5.1 ms when H 2 is added during Si-rich SiN x deposition, which is much higher than the case of using Si-rich SiN x films prepared without H 2 dilution showing τ eff of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiN x /SiN x stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H 2 gas during Si-rich SiN x film deposition greatly enhances effective minority carrier lifetime (τ eff ). • For a Si-rich SiN x film with refractive index of 2.92, τ eff improves from 3.3 to 5.1 ms by H 2 addition

  19. Low dose irradiation performance of SiC interphase SiC/SiC composites

    International Nuclear Information System (INIS)

    Snead, L.L.; Lowden, R.A.; Strizak, J.; More, K.L.; Eatherly, W.S.; Bailey, J.; Williams, A.M.; Osborne, M.C.; Shinavski, R.J.

    1998-01-01

    Reduced oxygen Hi-Nicalon fiber reinforced composite SiC materials were densified with a chemically vapor infiltrated (CVI) silicon carbide (SiC) matrix and interphases of either 'porous' SiC or multilayer SiC and irradiated to a neutron fluence of 1.1 x 10 25 n m -2 (E>0.1 MeV) in the temperature range of 260 to 1060 C. The unirradiated properties of these composites are superior to previously studied ceramic grade Nicalon fiber reinforced/carbon interphase materials. Negligible reduction in the macroscopic matrix microcracking stress was observed after irradiation for the multilayer SiC interphase material and a slight reduction in matrix microcracking stress was observed for the composite with porous SiC interphase. The reduction in strength for the porous SiC interfacial material is greatest for the highest irradiation temperature. The ultimate fracture stress (in four point bending) following irradiation for the multilayer SiC and porous SiC interphase materials was reduced by 15% and 30%, respectively, which is an improvement over the 40% reduction suffered by irradiated ceramic grade Nicalon fiber materials fabricated in a similar fashion, though with a carbon interphase. The degradation of the mechanical properties of these composites is analyzed by comparison with the irradiation behavior of bare Hi-Nicalon fiber and Morton chemically vapor deposited (CVD) SiC. It is concluded that the degradation of these composites, as with the previous generation ceramic grade Nicalon fiber materials, is dominated by interfacial effects, though the overall degradation of fiber and hence composite is reduced for the newer low-oxygen fiber. (orig.)

  20. Para tener entre manos una revista

    OpenAIRE

    Gabriel Giannone

    2017-01-01

    Consideramos importante rescatar el trabajo colectivo y acumulado que precede y sucede a la labor de intermediación académica que realiza una revista. Para ello recordamos una clásica frase prologal: el texto que usted tiene en sus manos. Con cierta ironía, porque quizás muy pocos de los lectores puedan tener entre manos y oler el papel impreso de Chasqui. Desde sus pantallas, sus tablets o sus teléfonos la intención es que se comprenda este número como un solo cuerpo. Y al mismo tiempo, como...

  1. Relación entre variables neurocognitivas y personalidad en delincuentes

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Directory of Open Access Journals (Sweden)

    Tea Štoka

    2005-12-01

    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.

  4. Grafted SiC nanocrystals

    DEFF Research Database (Denmark)

    Saini, Isha; Sharma, Annu; Dhiman, Rajnish

    2017-01-01

    ), raman spectroscopy and X-ray diffraction (XRD) measurements. UV–Visible absorption spectroscopy was used to study optical properties such as optical energy gap (Eg), Urbach's energy (Eu), refractive index (n), real (ε1) and imaginary (ε2) parts of dielectric constant of PVA as well as PVA......Polyvinyl alcohol (PVA) grafted SiC (PVA-g-SiC)/PVA nanocomposite was synthesized by incorporating PVA grafted silicon carbide (SiC) nanocrystals inside PVA matrix. In-depth structural characterization of resulting nanocomposite was carried out using fourier transform infrared spectroscopy (FTIR...

  5. Radiation emission from wrinkled SiGe/SiGe nanostructure

    Czech Academy of Sciences Publication Activity Database

    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

  6. Electrical properties of Si/Si1-xGex/Si inverted modulation doped structures

    International Nuclear Information System (INIS)

    Sadeghzadeh, M.A.

    1998-12-01

    This thesis is a report of experimental investigations of growth strategy and electrical properties of Si/Si 1-x Ge x /Si inverted Modulation Doped (MD) structures grown by solid source Molecular Beam Epitaxy (MBE). If the grown Si layer is B-doped at some distance (as spacer) before or after the alloy layer, this remote doping induces the formation of a quasi Two Dimensional Hole Gas (2-DHG) near to the inverted (SiGe on Si) or normal (Si on SiGe) heterointerfaces of the Si/Si 1-x Ge x /Si quantum well, respectively. The latter arrangement is the well known 'normal' MD structure but the former one is the so-called 'inverted' MD structure which is of great interest for Field Effect Transistor (FET) applications. A reproducible growth strategy was employed by the use of a thick (400nm) Si cap for inverted MD structures with Ge composition in the range of 16-23%. Boron segregation and cap surface charges are significant in these inverted structures with small ( 20nm) spacer layers, respectively. It was demonstrated by secondary ion mass spectroscopy (SIMS) that boron segregation, which causes a reduction in the effective spacer dimension, can be suppressed by growth interruption after boron doping. The enhancement in hole sheet density with increasing Si cap layer thickness, is attributed to a reduction in the influence of positive surface charges in these structures. Top-gated devices were fabricated using these structures and the hole sheet density could be varied by applying a voltage to the metal-semiconductor gate, and the maximum Hall mobility of 5550 cm 2 V -1 s -1 with 4.2x10 11 cm -2 was measured (at 1.6K) in these structures. Comparison of measured Hall mobility (at 4.2K) as a function of hole sheet density in normal and inverted MD structures implies that both 2-DHG confined at normal and/or inverted structures are subjected to very similar interface charge, roughness, and alloy scattering potentials. Low temperatures magnetotransport measurements (down to

  7. Entre la Venadita y la Medusa

    Directory of Open Access Journals (Sweden)

    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.

  8. Diferencias en comportamientos prosociales entre adolescentes colombianos

    Directory of Open Access Journals (Sweden)

    Jesús Redondo Pacheco

    2015-07-01

    Full Text Available Actualmente, se evidencia la influencia de variables socio-ambientales, como la cultura, el sexo, la edad o la nacionalidad, en la adquisición, desarrollo y mantenimiento de las conductas prosociales. El objetivo de este estudio fue analizar las diferencias en conductas prosociales entre estudiantes de educación secundaria de las ciudades de Pasto y Bucaramanga (Colombia, a quienes se administró la escala de Conducta Prosocial del TeenageInventory of Social Skills (TISS.Participaron 2.694 estudiantes con edades comprendidas entre 11 y 17 años (1878 de Pasto y 816 de Bucaramanga. De acuerdo con los resultados,los adolescentes de la ciudad de Pasto presentaron niveles significativamente más altos de conducta prosocial que los adolescentes de Bucaramanga. Este patrón de resultados fue similar por género y edad. Abstract This paper focuses on the analysis of pro-social behavior in high school students from Pasto and Bucaramanga (Colombia. 2,694 students between 11 and 17 years old (1878 from Pasto y 816 from Bucaramanga were sampled and a Pro-social Behavior Scale of Teenage Inventory of Social Skills (TISS was administered. As a result, this research shows teenagers from Pasto showed higher levels of pro-social behavior than those from Bucaramanga. Socio-environmental variables, such as culture, sex, age or nationality influence students´ pro-social behavior development and maintenance.

  9. Total Ionizing Dose Effects of Si Vertical Diffused MOSFET with SiO2 and Si3N4/SiO2 Gate Dielectrics

    Directory of Open Access Journals (Sweden)

    Jiongjiong Mo

    2017-01-01

    Full Text Available The total ionizing dose irradiation effects are investigated in Si vertical diffused MOSFETs (VDMOSs with different gate dielectrics including single SiO2 layer and double Si3N4/SiO2 layer. Radiation-induced holes trapping is greater for single SiO2 layer than for double Si3N4/SiO2 layer. Dielectric oxidation temperature dependent TID effects are also studied. Holes trapping induced negative threshold voltage shift is smaller for SiO2 at lower oxidation temperature. Gate bias during irradiation leads to different VTH shift for different gate dielectrics. Single SiO2 layer shows the worst negative VTH at VG=0 V, while double Si3N4/SiO2 shows negative VTH shift at VG=-5 V, positive VTH shift at VG=10 V, and negligible VTH shift at VG=0 V.

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

    International Nuclear Information System (INIS)

    Djenize, S.; Sreckovic, A.; Bukvic, 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 3s3p 22 D-3s 2 4p 2 P o , 3s 2 3d 2 D-3s 2 4f 2 F o , and 3s 2 4p 2 P o -3s 2 4d 2 D transitions, the Si III line intensity ratios in the 3s3d 3 D-3s4p 3 P o , 3s4p 3 P o -3s4d 3 D, 3s4p 3 P o -3s5s 3 S, 3s4s 3 S-3s4p 3 P o , and 3s4f 3 F o -3s5g 3 G transitions, and the Si IV line intensity ratios in the 4p 2 P o -4d 2 D and 4p 2 P o -5s 2 S 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.

  11. Diferencias de personalidad entre matutinos y vespertinos

    OpenAIRE

    Virginia Dresch; María del Pilar Sánchez López; Marta Evelia Aparicio García

    2005-01-01

    El objetivo de este estudio era determinar si los sujetos con distinta tipología circadiana (matutinidad-vespertinidad) tenían un perfil de personalidad diferencial, trascendiendo el intento de relacionar la tipología circadiana con variables de personalidad aisladas y más generales, como Extraversión-Introversión. La investigación se llevó a cabo con 804 participantes, universitarios de una universidad del sur de Brasil (Novo Hamburgo-RS/BR) de 33 carreras distintas, utilizándose el MIPS Inv...

  12. Motivações do conceito de corpo-si: corpo-si, atividade, experiência = Motivations of the concept of selfbody: selfbody, activity, experience

    Directory of Open Access Journals (Sweden)

    Schwartz, Yves

    2014-01-01

    Full Text Available Este texto busca explicar a função de convergências e questões possibilitadoras do desenvolvimento da tese segundo a qual toda atividade de trabalho é sempre “uso de si, por si e por outros” (SCHWARTZ, 1987. Sucessivas reformulações levaram ao estabelecimento do seguinte princípio: toda atividade industriosa é sempre uma “dramática do uso de um corpo-si” (remetendo “dramática” à necessidade contínua de travar debates com normas. Sendo a atividade humana identificada assim como um contínuo debate de normas cujo lócus é o corpo-si, convém perguntar como, em termos de diferentes medidas temporais, esses debates se encaixam (à maneira das bonecas russas, ou seja, de que maneira as relações valorativas nos meios de vida e de trabalho se incorporam ao âmago do corpo-si, inclusive em termos de temporalidades mais curtas, “escondidas no corpo”. Cabe assim entender qual é a unidade enigmática dessa entidade – o corpo-si – que acumula experiência e saberes de formas extremamente diversas, notadamente em sua relação com a linguagem, que articula patrimônio epistêmico e sensibilidade axiológica, sem deixar de estar disponível para ou restrita por micro-escolhas e reajustamentos que a vida não cessa de lhe propor ou impor. O texto, retomando parcialmente, segundo seus objetivos, a distinção entre idem e ipse (RICOEUR, pretende conceber debates de normas encaixados como o cerne da dialética entre essas dimensões

  13. SiC Nanoparticles Toughened-SiC/MoSi2-SiC Multilayer Functionally Graded Oxidation Protective Coating for Carbon Materials at High Temperatures

    Science.gov (United States)

    Abdollahi, Alireza; Ehsani, Naser; Valefi, Zia; Khalifesoltani, Ali

    2017-05-01

    A SiC nanoparticle toughened-SiC/MoSi2-SiC functionally graded oxidation protective coating on graphite was prepared by reactive melt infiltration (RMI) at 1773 and 1873 K under argon atmosphere. The phase composition and anti-oxidation behavior of the coatings were investigated. The results show that the coating was composed of MoSi2, α-SiC and β-SiC. By the variations of Gibbs free energy (calculated by HSC Chemistry 6.0 software), it could be suggested that the SiC coating formed at low temperatures by solution-reprecipitation mechanism and at high temperatures by gas-phase reactions and solution-reprecipitation mechanisms simultaneously. SiC nanoparticles could improve the oxidation resistance of SiC/MoSi2-SiC multiphase coating. Addition of SiC nanoparticles increases toughness of the coating and prevents spreading of the oxygen diffusion channels in the coating during the oxidation test. The mass loss and oxidation rate of the SiC nanoparticle toughened-SiC/MoSi2-SiC-coated sample after 10-h oxidation at 1773 K were only 1.76% and 0.32 × 10-2 g/cm3/h, respectively.

  14. La publicidad encubierta en Instagram : análisis comparado de la regulación de la publicidad encubierta entre España y Estados Unidos

    OpenAIRE

    Monerris Valentí, Paula

    2017-01-01

    El present treball constitueix una anàlisi comparat entre Espanya i els Estats Units en referència a la publicitat encoberta a la plataforma Instagram. El principal objectiu és el d'investigar si hi ha diferències significatives en la manera com aquests països regulen i autoregulen aquesta pràctica. El presente trabajo constituye un análisis comparado entre España y Estados Unidos en referencia a la publicidad encubierta en la plataforma Instagram. El principal objetivo es el de investigar...

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

    OpenAIRE

    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 ...

  16. Entre angústia e desamparo

    Directory of Open Access Journals (Sweden)

    Jacques André

    2001-12-01

    Full Text Available Em sua discussão, o autor diz que a angústia é o motor da análise e de seu progresso: em si mesma é abertura para os enigmas do interior. O desamparo, por sua vez, indica que a vida psíquica continua a ser vivida fora de si, na desesperada abertura para um outro que não responde. Então, na análise, se uma mobiliza, o outro paralisa. O amor (compreendido em sua parte não narcísica é "agarrar-se" aos objetos do mundo exterior, é abertura mantida para o outro e, nesse ponto, homogênea do estado de desamparo do bebê.Between anxiety and helplessness. In this paper the author states that anxiety is the engine of both analysis and its progress: in itself it is an opening to the puzzles of the interior. Helplessness, on the other hand, points out that psychic life is still being lived out of oneself, in a desperate opening to an unresponsive other. So, under the analysis point of view, while one mobilizes, the other paralyses. Love (out of its narcissistic part is "to cling" to objects of the external world, it is an opening to the other and, at that point, homogeneous to the baby's state of helplessness.

  17. Growth of CNTs on Fe-Si catalyst prepared on Si and Al coated Si substrates

    International Nuclear Information System (INIS)

    Teng, F-Y; Ting, J-M; Sharma, Sahendra P; Liao, Kun-Hou

    2008-01-01

    In this paper we report the effect of Al interlayers on the growth characteristics of carbon nanotubes (CNTs) using as-deposited and plasma etched Fe-Si catalyst films as the catalysts. Al interlayers having various thicknesses ranging from 2 to 42 nm were deposited on Si substrates prior to the deposition of Fe-Si catalysts. It was found that the Al interlayer diffuses into the Fe-Si catalyst during the plasma etching prior to the CNT growth, leading to the swelling and amorphization of the catalyst. This allows enhanced carbon diffusion in the catalyst and therefore a faster growth rate of the resulting CNTs. It was also found that use of an Al interlayer having a thickness of ∼3 ± 1 nm is most effective. Due to the effectiveness of this, the normally required catalyst etching is no longer needed for the growth of CNTs

  18. Growth of CNTs on Fe-Si catalyst prepared on Si and Al coated Si substrates.

    Science.gov (United States)

    Teng, F-Y; Ting, Jyh-Ming; Sharma, Sahendra P; Liao, Kun-Hou

    2008-03-05

    In this paper we report the effect of Al interlayers on the growth characteristics of carbon nanotubes (CNTs) using as-deposited and plasma etched Fe-Si catalyst films as the catalysts. Al interlayers having various thicknesses ranging from 2 to 42 nm were deposited on Si substrates prior to the deposition of Fe-Si catalysts. It was found that the Al interlayer diffuses into the Fe-Si catalyst during the plasma etching prior to the CNT growth, leading to the swelling and amorphization of the catalyst. This allows enhanced carbon diffusion in the catalyst and therefore a faster growth rate of the resulting CNTs. It was also found that use of an Al interlayer having a thickness of ∼3 ± 1 nm is most effective. Due to the effectiveness of this, the normally required catalyst etching is no longer needed for the growth of CNTs.

  19. La resistenza, entre memoria y revisionismo

    Directory of Open Access Journals (Sweden)

    Massimiliano Vellini

    2013-07-01

    Full Text Available La Resistenza es sin duda un momento clave de la historia italiana del siglo XX. Pero, a pesar de haber sido narrada en muchas obras tanto literarias como en ensayos, aún hay detalles e historias que quizás no sean conocidas por el público no especializado. Además, sobre todo en los últimos años, ha habido cada vez un mayor número de obras de periodistas o historiadores que han dado del movimiento una visión bastante alejada de la tradicionalmente dominante. En este artículo queremos dar una idea de estos episodios menos conocidos de la Resistenza partigiana y de la diatriba entre diferentes visiones de la misma.

  20. Para tener entre manos una revista

    Directory of Open Access Journals (Sweden)

    Gabriel Giannone

    2017-12-01

    Full Text Available Consideramos importante rescatar el trabajo colectivo y acumulado que precede y sucede a la labor de intermediación académica que realiza una revista. Para ello recordamos una clásica frase prologal: el texto que usted tiene en sus manos. Con cierta ironía, porque quizás muy pocos de los lectores puedan tener entre manos y oler el papel impreso de Chasqui. Desde sus pantallas, sus tablets o sus teléfonos la intención es que se comprenda este número como un solo cuerpo. Y al mismo tiempo, como un esfuerzo colectivo. Alrededor de él están las propuestas, lecturas y análisis de cientos de autores, revisores externos y lectores.

  1. Las relaciones compositivas entre cine y arquitectura

    Directory of Open Access Journals (Sweden)

    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.

  2. SI units in engineering and technology

    CERN Document Server

    Qasim, S H

    2016-01-01

    SI Units in Engineering and Technology focuses on the use of the International System of Units-Systeme International d'Unités (SI). The publication first elaborates on the SI, derivation of important engineering units, and derived SI units in science and engineering. Discussions focus on applied mechanics in mechanical engineering, electrical and magnetic units, stress and pressure, work and energy, power and force, and magnitude of SI units. The text then examines SI units conversion tables and engineering data in SI units. Tables include details on the sectional properties of metals in SI units, physical properties of important molded plastics, important physical constants expressed in SI units, and temperature, area, volume, and mass conversion. Tables that show the mathematical constants, standard values expressed in SI units, and Tex count conversion are also presented. The publication is a dependable source of data for researchers interested in the use of the International System of Units-Systeme Inter...

  3. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    International Nuclear Information System (INIS)

    Wu Yuying; Liu Xiangfa; Jiang Binggang; Huang Chuanzhen

    2009-01-01

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  4. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China)], E-mail: wyy532001@163.com; Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602, Shandong (China); Jiang Binggang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Huang Chuanzhen [School of Mechanical Engineering, Shandong University, Jinan 250061 (China)

    2009-05-27

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  5. Correlación entre los resultados de valoración funcional y de fuerza de la rodilla en pacientes con rotura del ligamento cruzado anterior

    OpenAIRE

    Álvarez Santana, David

    2016-01-01

    Programa de doctorado: Avances en Traumatología. Medicina del Deporte. Cuidado de Heridas. La fecha de publicación es la fecha de lectura [ES]Objetivos: Determinar si existen diferencias en la fuerza isométrica en la rodilla afecta con respecto a la sana en pacientes con rotura de LCA y un grupo control. Estudiar si existe correlación significativa entre el desplazamiento tibial, la fuerza isométrica generada por la musculatura de las rodillas, los resultados en cuestionarios de valoración...

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

    Science.gov (United States)

    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.

  7. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    International Nuclear Information System (INIS)

    Jeon, Bup Ju; Lee, Joong Kee

    2014-01-01

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH 4 /SiH 4 mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH 4 and SiH 4 precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium

  8. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Bup Ju [Department of Energy Resources, Shinhan University, 233-1, Sangpae-dong, Dongducheon, Gyeonggi-do, 483-777 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Advanced Energy Materials Processing Laboratory, Center for Energy Convergence Research, Green City Technology Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2014-03-25

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH{sub 4}/SiH{sub 4} mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH{sub 4} and SiH{sub 4} precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium.

  9. Circumferential tensile test method for mechanical property evaluation of SiC/SiC tube

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ju-Hyeon, E-mail: 15096018@mmm.muroran-it.ac.jp [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Park, Joon-soo [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Nakazato, Naofumi [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE SiC/SiC cooling channel system to be a candidate of divertor system in future. • Hoop strength is one of the important factors for a tube. • This research studies the relationship between deformation and strain of SiC/SiC tube. - Abstract: SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate material for the first-wall, components in the blanket and divertor of fusion reactors in future. In such components, SiC/SiC composites need to be formed to be various shapes. SiC/SiC tubes has been expected to be employed for blanket and divertor after DEMO reactor, but there is not established mechanical investigation technique. Recent progress of SiC/SiC processing techniques is likely to realize strong, having gas tightness SiC/SiC tubes which will contribute for the development of fusion reactors. This research studies the relationship between deformation and strain of SiC/SiC tube using a circumferential tensile test method to establish a mechanical property investigation method of SiC/SiC tubes.

  10. Si, Ge and SiGe wires for sensor application

    International Nuclear Information System (INIS)

    Druzhinin, A.A.; Khoverko, Yu.M.; Ostrovskii, I.P.; Nichkalo, S.I.; Nikolaeva, A.A.; Konopko, L.A.; Stich, I.

    2011-01-01

    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)

  11. Doping effect in Si nanocrystals

    Science.gov (United States)

    Li, Dongke; Xu, Jun; Zhang, Pei; Jiang, Yicheng; Chen, Kunji

    2018-06-01

    Intentional doping in semiconductors is a fundamental issue since it can control the conduction type and ability as well as modify the optical and electronic properties. To realize effective doping is the basis for developing semiconductor devices. However, by reducing the size of a semiconductor, like Si, to the nanometer scale, the doping effects become complicated due to the coupling between the quantum confinement effect and the surfaces and/or interfaces effect. In particular, by introducing phosphorus or boron impurities as dopants into material containing Si nanocrystals with a dot size of less than 10 nm, it exhibits different behaviors and influences on the physical properties from its bulk counterpart. Understanding the doping effects in Si nanocrystals is currently a challenge in order to further improve the performance of the next generation of nano-electronic and photonic devices. In this review, we present an overview of the latest theoretical studies and experimental results on dopant distributions and their effects on the electronic and optical properties of Si nanocrystals. In particular, the advanced characterization techniques on dopant distribution, the carrier transport process as well as the linear and nonlinear optical properties of doped Si nanocrystals, are systematically summarized.

  12. Reaction mechanisms at 4H-SiC/SiO2 interface during wet SiC oxidation

    Science.gov (United States)

    Akiyama, Toru; Hori, Shinsuke; Nakamura, Kohji; Ito, Tomonori; Kageshima, Hiroyuki; Uematsu, Masashi; Shiraishi, Kenji

    2018-04-01

    The reaction processes at the interface between SiC with 4H structure (4H-SiC) and SiO2 during wet oxidation are investigated by electronic structure calculations within the density functional theory. Our calculations for 4H-SiC/SiO2 interfaces with various orientations demonstrate characteristic features of the reaction depending on the crystal orientation of SiC: On the Si-face, the H2O molecule is stable in SiO2 and hardly reacts with the SiC substrate, while the O atom of H2O can form Si-O bonds at the C-face interface. Two OH groups are found to be at least necessary for forming new Si-O bonds at the Si-face interface, indicating that the oxidation rate on the Si-face is very low compared with that on the C-face. On the other hand, both the H2O molecule and the OH group are incorporated into the C-face interface, and the energy barrier for OH is similar to that for H2O. By comparing the calculated energy barriers for these reactants with the activation energies of oxide growth rate, we suggest the orientation-dependent rate-limiting processes during wet SiC oxidation.

  13. Analyses of the As doping of SiO{sub 2}/Si/SiO{sub 2} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, Francesco; Miritello, Maria [CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Tomasello, Mario Vincenzo [Scuola Superiore di Catania, via San Nullo 5/i, 95123 Catania (Italy); De Bastiani, Riccardo; Grimaldi, Maria Grazia [Dipartimento di Fisica ed Astronomia, Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Nicotra, Giuseppe; Spinella, Corrado [Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), VIII Strada 5, 95121 Catania (Italy)

    2011-03-15

    We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}(70nm)/Si(30nm)/SiO{sub 2}(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO{sub 2} interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO{sub 2} interfaces was estimated in 10{sup 14} traps/cm{sup 2}. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. El tratado secreto del Barón de Río Branco: la alianza entre Brasil y Ecuador, 1904

    Directory of Open Access Journals (Sweden)

    Luís Cláudio Villafañe G. Santos

    2016-06-01

    Full Text Available Es casi desconocida en las historiografías de Brasil y Ecuador la existencia de un tratado militar secreto entre ambos países, rmado el 5 de mayo de 1904, dirigido contra las pretensiones territoriales de Perú. El artículo estudia una creciente tensión entre Brasil y Perú, que disputaban un área de 442 mil kilómetros cuadrados en la Amazonía. Por iniciativa del Barón de Río Branco, se rmó un tratado secreto de alianza militar entre Brasil y Ecuador. Si bien este acuerdo no fue raticado por los países rmantes, fue de suma importancia para forzar al gobierno peruano a iniciar negociaciones con Brasil, que años más tarde resultaron en el tratado de límites entre los dos países.

  15. Profundidade superficial e superficialidade profunda: O dilema da pesquisa em ciências humanas entre a disciplinaridade e a interdisciplinaridade

    Directory of Open Access Journals (Sweden)

    Cláudio Clécio Vidal Eufrausino

    2008-06-01

    Full Text Available O objetivo deste artigo é discutir a necessidade de repensar o conflito entre disciplinaridade e interdisciplinaridade como se fossem opostos irreconciliáveis. Tentamos demonstrar que a riqueza das ciências humanas cresce através do confronto aberto entre estas duas modalidades de pesquisa, a fim de serem preenchidas as lacunas de ambas. Por meio desta análise, procuramos dar um novo significado para os termos superficialidade e profundidade, tentando superar a antiga oposição que considera profundidade como uma coisa boa em oposição ao caráter superficial. Ao fazermos isto, estamos revendo, com auxílio da teoria de Carlo Ginsburg, a oposição entre retórica e prova, ou, em outros termos, entre factualidade e demonstração argumentativa. Através do enfrentamento dos limites tanto da disciplinaridade quanto da interdisciplinaridade, tentamos apontar novas direções científicas, mostrando soluções marcantes não pelo poder que contêm em si mesmas, mas pela capacidade delas de estimular uma freqüente revisão dos paradigmas das ciências.

  16. Experiencias de calorimetría diferencial de barrido en aleaciones Al-Si

    Directory of Open Access Journals (Sweden)

    Carolina López-Eckerdt

    2016-01-01

    Full Text Available La observación de agujas características de una transformación displaciva en aleaciones U-Al-Si en el entorno del compuesto U3Si5 evidencia la necesidad de analizar las distintas transformaciones que ocurren durante el enfriamiento utilizando una técnica dinámica de identificación de transformaciones (calorimetría diferencial de barrido. Para evaluar la versatilidad de esta técnica, se estudiaron aleaciones Al-Si con concentraciones de Si entre 0,6% y 7,1% en peso. Se determinaron las temperaturas liquidus y eutéctica de cada aleación y se estimó la entalpía de formación de los precipitados de Si y de la reacción eutéctica. Los resultados reproducen las temperaturas de ambas reacciones según el diagrama de equilibrio del sistema binario Al-Si. Para el cálculo de las entalpías de transformación resulta indispensable obtener el porcentaje de fase transformada por otras técnicas de caracterización una vez finalizado el ensayo.

  17. High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

    Science.gov (United States)

    Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

    2018-03-01

    The influence was studied of 22-MeV electron irradiation on Si-SiO2 structures implanted with high-fluence Si+ ions. Our earlier works demonstrated that Si redistribution is observed in Si+-ion-implanted Si-SiO2 structures (after MeV electron irradiation) only in the case when ion implantation is carried out with a higher fluence (1016 cm-2). We focused our attention on the interaction of high-dose MeV electron irradiation (6.0×1016 cm-2) with n-Si-SiO2 structures implanted with Si+ ions (fluence 5.4×1016 cm-2 of the same order magnitude). The redistribution of both oxygen and silicon atoms in the implanted Si-SiO2 samples after MeV electron irradiation was studied by Rutherford back-scattering (RBS) spectroscopy in combination with a channeling technique (RBS/C). Our results demonstrated that the redistribution of oxygen and silicon atoms in the implanted samples reaches saturation after these high doses of MeV electron irradiation. The transformation of amorphous SiO2 surface into crystalline Si nanostructures (after MeV electron irradiation) was evidenced by atomic force microscopy (AFM). Silicon nanocrystals are formed on the SiO2 surface after MeV electron irradiation. The shape and number of the Si nanocrystals on the SiO2 surface depend on the MeV electron irradiation, while their size increases with the dose. The mean Si nanocrystals height is 16-20 nm after irradiation with MeV electrons at the dose of 6.0×1016 cm-2.

  18. Thermal shock properties of 2D-SiCf/SiC composites

    International Nuclear Information System (INIS)

    Lee, Sang Pill; Lee, Jin Kyung; Son, In Soo; Bae, Dong Su; Kohyama, Akira

    2012-01-01

    This paper dealt with the thermal shock properties of SiC f /SiC composites reinforced with two dimensional SiC fabrics. SiC f /SiC composites were fabricated by a liquid phase sintering process, using a commercial nano-size SiC powder and oxide additive materials. An Al 2 O 3 –Y 2 O 3 –SiO 2 powder mixture was used as a sintering additive for the consolidation of SiC matrix region. In this composite system, Tyranno SA SiC fabrics were also utilized as a reinforcing material. The thermal shock test for SiC f /SiC composites was carried out at the elevated temperature. Both mechanical strength and microstructure of SiC f /SiC composites were investigated by means of optical microscopy, SEM and three point bending test. SiC f /SiC composites represented a dense morphology with a porosity of about 8.2% and a flexural strength of about 160 MPs. The characterization of SiC f /SiC composites was greatly affected by the history of cyclic thermal shock. Especially, SiC f /SiC composites represented a reduction of flexural strength at the thermal shock temperature difference higher than 800 °C.

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

    International Nuclear Information System (INIS)

    Kowbel, W.; Tsou, K.T.; Withers, J.C.; Youngblood, G.E.

    1998-01-01

    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

  20. 32Si dating of sediments

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2004-01-01

    Brief explanation of the use of 32 Si in the dating of sediments. 32 Si , with a half-life of c.140 years, can be applied in the age range 30-1000 years. An appropriate dating tool for that time range is essential because it includes three very important epochs: the impact of human colonisation and industrialisation during the last 150 years, the Little Ice Age between about 1650 AD and 1850 AD, and the last part of the Medieval Climatic Optimum. 23 refs

  1. SI units in radiation protection

    International Nuclear Information System (INIS)

    Herrmann, D.

    1976-10-01

    In the field of radiation protection all hitherto used units for activity, activity concentrations, exposure, absorbed dose, and dose rates have to be replaced by SI units during the next years. For this purpose graphs and conversion tables are given as well as recommendations on unit combinations preferentially to be used. As to the dose equivalent, it is suggested to introduce a new special unit being 100 times greater than the rem, instead of maintaining the rem or using the gray for both absorbed dose and dose equivalent. Measures and time schedule relating to the gradual transition to SI units in measuring techniques, training, and publishing et cetera are explained. (author)

  2. No se puede asegurar la existencia de asociación entre tratamiento del síndrome de déficit de atención con estimulantes y mayor incidencia de muerte súbita

    OpenAIRE

    Fernando Carvajal, Encina; Buñuel Álvarez, José Cristóbal

    2009-01-01

    El objetivo de este artículo es determinar si existe asociación entre la muerte súbita (MS) y el tratamiento con medicamentos estimulantes del sistema nervioso central (SNC) utilizados para el tratamiento del síndrome de déficit de atención con hiperactividad (TDAH).

  3. Cavities at the Si projected range by high dose and energy Si ion implantation in Si

    International Nuclear Information System (INIS)

    Canino, M.; Regula, G.; Lancin, M.; Xu, M.; Pichaud, B.; Ntzoenzok, E.; Barthe, M.F.

    2009-01-01

    Two series of n-type Si samples α and β are implanted with Si ions at high dose (1 x 10 16 ) and high energies, 0.3 and 1.0 MeV, respectively. Both sort of samples are then implanted with 5 x 10 16 He cm -2 (at 10 or 50 keV) and eventually with B atoms. Some of the samples are annealed at temperatures ranging from 800 to 1000 deg. C to allow the thermal growth of He-cavities, located between sample surface and the projected range (R p ) of Si. After the triple ion implantation, which corresponds to defect engineering, samples were characterized by cross-section transmission electron microscopy (XTEM). Voids (or bubbles) are observed not only at the R p (He) on all annealed samples, but also at the R p (Si) on β samples implanted with He at 50 keV. The samples are also studied by positron annihilation spectroscopy (PAS) and the spectra confirm that as-implanted samples contain di-vacancies and that the annealed ones, even at high temperature have bigger open volumes, which are assumed to be the same voids observed by XTEM. It is demonstrated that a sole Si implantation at high energy and dose is efficient to create cavities which are thermally stable up to 1000 deg. C only in the presence of He.

  4. Analysis of Si/SiGe Heterostructure Solar Cell

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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...

  6. Correlación entre el Clima Organizacional Percibido por los Trabajadores de Salud y su Compromiso Organizacional en la Micro Red Edificadores Misti-Minsa, Arequipa 2008

    OpenAIRE

    Flores Flores Ricardina

    2010-01-01

    Se realizó una investigación sobre el clima organizacional percibido por los trabajadores de salud y su compromiso organizacional en la Micro Red Edificadores Misti. El tipo de estudio es transversal y correlacional para explorar si existe una correlación directa entre el clima y el compromiso organizacional. Se plantearon como objetivos caracterizar el clima y compromiso organizacional para luego determinar su correlación. El instrumento que se utiliza es de Litwin y Stinger c...

  7. ARTESANATO: ENTRE PATRIMÔNIO E MERCADO

    Directory of Open Access Journals (Sweden)

    Miriel Bilhalva Herrmann

    2016-12-01

    Full Text Available O presente trabalho busca estabelecer uma analise em relação a questão do artesanato, de como sofre modificações e interferências . Na qual no seu inicio tinha apenas valor utilitário, pois era produzido para suprir necessidades humanas. E com a revolução industrial foi relegada a marginalização, assim perdeu seu espaço para as máquinas. Mas logo com o intuito de criar identidades nacionais, começam as discussões em relação ao patrimônio. Dessa forma as concepções e ampliação sobre o seu conceito, propiciou grande valorização das diversidades culturais, assim como as técnicas artesanais. E a partir disso o artesanato passa a ser percebido como patrimônio, sendo visto e utilizado pelo turismo como fator de desenvolvimento econômico, dessa forma ocasionando um dilema entre estas técnicas artesanais de como se manter tradicionais, referência para a cultura e a identidade cultural. Ao mesmo tempo atender as necessidades do consumidor que se apresenta como turista, pois necessitam se adaptar para continuar sobrevivendo as mudanças do mercado

  8. Entre la Historia y el Cine

    Directory of Open Access Journals (Sweden)

    Luisa Fernanda Acosta

    1995-01-01

    Full Text Available Este trabajo se propone aplicar al cine el concepto de «fuente histórica». El uso de medios de comunicación como el cine está íntimamente relacionado con las necesidades y posibilidades de una sociedad, lo que implica una relación muy cercana entre el desarrollo social y económico de una comunidad, y los mecanismos que ella genera como canales de expresión y comunicación. El cine, conjugación de imagen, sonido y movimiento se convierte para la sociedades contemporáneas en una gran alternativa como fuente histórica, que provee al investigador ópticas diferentes de una realidad ya explorada. Un gesto, una mirada, un plano, una secuencia, se traducen en frases y párrafos, que generan una versión diferente de la historia, una redacción que se lee en imágenes y que narra otro punto de vista, un relato oculto que tiene todo por contar.

  9. Acidentes de trabalho ocorridos entre adolescentes

    Directory of Open Access Journals (Sweden)

    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.

  10. Relación entre work engagement y capital psicológico en una muestra de profesorado universitario

    OpenAIRE

    Freire Moure, Martina

    2016-01-01

    Traballo Fin de Grao en Psicoloxía. Curso 2015-2016 [ES] El work engagement y el capital psicológico son dos conceptos que han ganado gran popularidad en los últimos años. Sin embargo, son escasos los estudios que se han llevado a cabo para determinar si existe relación entre ambos, especialmente en profesorado universitario. En este estudio, se tiene en cuenta la conceptualización de work engagement desarrollada por Schaufeli, Salanova, González-Romá y Bakker (2002), así como la conceptua...

  11. ¿Qué relación existe entre la Perdurabilidad Empresarial Colombiana y las creencias religiosas del directivo?

    OpenAIRE

    Pinzón Mojica, Hernan Mauricio; Pinto Molina, Diana Carolina

    2011-01-01

    En el ámbito empresarial, durante mucho tiempo y aún en la actualidad, la religión se ha visto como un tema aparte. Sin embargo, la literatura del desarrollo empresarial colombiano muestra que en los inicios del siglo XX la religión tuvo una fuerte influencia tanto en los dirigentes empresariales como en la mentalidad de los empleados. No obstante, antes de entrar a discutir si existe alguna relación entre la religión que tiene el empresario y la perdurabilidad empresarial -que...

  12. Entre el silencio y la impunidad: violencia sexual en escenarios de conflicto

    Directory of Open Access Journals (Sweden)

    Marta Torres Falcón

    2015-01-01

    Full Text Available El artículo analiza la violencia sexual contra las mujeres en escenarios de conflicto armado en América Latina. Los temas principales son el vínculo entre violencia social y violencia de género, el concepto de violencia sexual en la teoría y práctica de los derechos humanos y su alta incidencia en situaciones de conflicto. En distintos espacios sociales, la violencia contra las mujeres es invisible (o invisibilizada, aun si es extrema. La definición de la violencia sexual como crimen de lesa humanidad es muy reciente y sigue siendo controvertida. Sin embargo, se han dado ya pasos importantes en este proceso.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Burnout e intenciones de jubilación anticipada entre empleados mayores

    Directory of Open Access Journals (Sweden)

    Kène Henkens

    2008-01-01

    Full Text Available 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 si existe una relación entre las intenciones de jubilación y las características del puesto de trabajo, el apoyo social y la autoeficacia, así como con las citadas dimensiones del burnout. Los datos proceden de una investigación con empleados holandeses y sus parejas (N=2.892. Los resultados permiten ver que la carga laboral excesiva, un trabajo duro desde el punto de vista físico y una ausencia demasiado grande de desafíos están relacionados con los sentimientos de agotamiento emocional. La despersonalización se explica por la escasez de desafíos en el trabajo, la carga laboral excesiva, una falta de apoyo social por parte de los compañeros y una baja autoeficacia. El agotamiento emocional, la despersonalización y las relaciones conyugales explican en gran medida las intenciones de jubilación. El burnout y el proceso de jubilación están muy relacionados, pero parecen ser hasta cierto punto dos procesos diferentes. Mientras que el burnout se determina esencialmente dentro del entorno laboral, los factores externos al trabajo son cruciales en la comprensión de la jubilación.

  16. Relación entre el período de lactancia materna y maloclusiones

    Directory of Open Access Journals (Sweden)

    Rosa Gabriela Rondón

    2012-02-01

    Full Text Available Los beneficios de la lactancia materna en la prevención de las maloclusiones han sido descritos en la literatura odontológica, destacando que lactar exclusivamente más de 6 meses disminuye su prevalencia. Objetivo: determinar la relación entre periodo de Lactancia Materna y Maloclusiones. Material y métodos: se examinó una muestra de 59 niños en edades entre 6 y 13 años en la parroquia Higuerote, Miranda, Venezuela. Se aplicó un cuestionario a cada representante para obtener datos sobre el periodo de lactancia materna recibida por el niño y se efectuó un examen clínico bucal observando variables ortodóncicas en cada niño. Se realizó un modelo de análisis de significancia p<0,05, mediante la prueba de Fisher a través del Análisis de Varianza Univariado (ANOVA, para evidenciar si existían diferencias estadísticamente significativas entre periodo de lactancia materna y las variables: relación molar permanente, mordida abierta anterior y mordida cruzada posterior. También se aplicó la prueba no paramétrica de Kruskal-Wallis en aquellos casos en donde la muestra fue menor de 30 observaciones. Resultados: existe relación estadística significativa entre un periodo de lactancia materna menor de 6 meses y relación molar en clase II de Angle y mordida abierta anterior, sin embargo para mordida cruzada posterior no se halló significancia estadística. Se encontró relación estadísticamente significativa entre un periodo de lactancia materna mayor de 6 meses con relación molar en clase I de Angle. Conclusión: se plantea que un periodo de lactancia materna mayor de 6 meses se relaciona con la ausencia de maloclusión en el grupo estudiado.

  17. Development and validation of a method for detection and quantification of ochratoxin A in green coffee using liquid chromatography coupled to mass spectrometry Desenvolvimento e validação de metodologia na detecção e na quantificação de Ocratoxina A no café verde utilizando cromatografia líquida acoplada à espectrometria de massas

    Directory of Open Access Journals (Sweden)

    Raquel Duarte da Costa Cunha Bandeira

    2012-12-01

    Full Text Available A method using Liquid Chromatography Tanden Mass Spectrometry (LC-MS/MS with matrix-matched calibration curve was developed and validated for determining ochratoxin A (OTA in green coffee. Linearity was found between 3.0 and 23.0 ng.g-1. Mean recoveries ranged between 90.45% and 108.81%; the relative standard deviation under repeatability and intermediate precision conditions ranged from 5.39% to 9.94% and from 2.20% to 14.34%, respectively. The limits of detection and quantification were 1.2 ng.g-1 and 3.0 ng.g-¹, respectively. The method developed was suitable and contributed to the field of mycotoxin analysis, and it will be used for future production of the Certified Reference Material (CRM for OTA in coffee.Um método utilizando Cromatografia Líquida de Alta Eficiência-Espectrometria de Massas Sequencial (CLAE-EM/EM com curva de calibração em matriz foi desenvolvido e validado para a determinação de ocratoxina A (OTA em café verde. A linearidade foi demonstrada entre 3,0 e 23,0 ng.g-1. As recuperações médias variaram entre 90,45% e 108,81%; o desvio padrão relativo sob condições de repetitividade e precisão intermediária foram de 5,39% e 9,94% e de 2,20% e 14,34%, respectivamente. Os limites de detecção e quantificação foram 1,2 ng.g-1 e 3,0 ng.g-, respectivamente. O método desenvolvido foi adequado, contribuiu para o campo de análises em micotoxinas e será usado para a futura produção de Material de Referência Certificado (MRC para OTA em café.

  18. Microestructura y propiedades mecánicas del SiC biomórfico obtenido a partir de eucalipto

    Directory of Open Access Journals (Sweden)

    Presas, M.

    2005-12-01

    Full Text Available The development of cellular ceramics with a biological structure, like bones and wood, has been a matter of interest in recent years. A low density highly interconnected structure, perfected by evolution, rises as the principal advantage of these materials. In the case of biomimetic SiC (biomorphic SiC, or bioSiC, the fabrication process technique is quite simple: a piece of wood is pyrolysed and is infiltrated with molten silicon after, the final product is a composite Si/SiC, which replicates the wood anisotropic microstructure This work focus on the mechanical properties of bioSiC fabricated using eucalyptus wood as precursor (hard wood with a bimodal channel distribution. It has been studied the mechanical behavior of this bioSiC (compression strength, flexure strength, fracture toughness and elastic modulus between 25 and 1350 oC. It is also discussed the relationship between mechanical behavior of the material and its microstructure.

    El desarrollo de materiales cerámicos con una estructura de tipo celular, similar a la del hueso o la madera, ha sido una cuestión que ha suscitado un gran interés en los últimos años. Su atractivo se debe al hecho de poseer una estructura porosa altamente interconectada de baja densidad, perfeccionada por la evolución. En el caso del SiC biomórfico (bio-SiC el proceso de fabricación es sencillo: se piroliza una pieza de madera y a continuación se inyecta con silicio líquido, el material así obtenido es un compuesto Si/SiC en el que el SiC mimetiza la estructura de la madera original. En este trabajo se estudian las propiedades mecánicas del SiC biomórfico fabricado a partir de eucalipto (madera dura con una distribución bimodal de poros. Se ha estudiado el comportamiento mecánico del mismo (resistencia a compresión, resistencia a flexión, tenacidad de fractura y módulo de elasticidad entre 25 y 1350 oC. Asimismo, se discute la relación entre el comportamiento mecánico del material y

  19. Relaciones entre asertividad y estilos cognitivos

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    Xu, Jie; Xu, Jun; Wang, Yuefei; Cao, Yunqing; Li, Wei; Yu, Linwei; Chen, Kunji

    2014-01-01

    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)

  1. Pressureless sintering of dense Si3N4 and Si3N4/SiC composites with nitrate additives

    International Nuclear Information System (INIS)

    Kim, J.Y.; Iseki, Takayoshi; Yano, Toyohiko

    1996-01-01

    The effect of aluminum and yttrium nitrate additives on the densification of monolithic Si 3 N 4 and a Si 3 N 4 /SiC composite by pressureless sintering was compared with that of oxide additives. The surfaces of Si 3 N 4 particles milled with aluminum and yttrium nitrates, which were added as methanol solutions, were coated with a different layer containing Al and Y from that of Si 3 N 4 particles milled with oxide additives. Monolithic Si 3 N 4 could be sintered to 94% of theoretical density (TD) at 1,500 C with nitrate additives. The sintering temperature was about 100 C lower than the case with oxide additives. After pressureless sintering at 1,750 C for 2 h in N 2 , the bulk density of a Si 3 N 4 /20 wt% SiC composite reached 95% TD with nitrate additives

  2. Si-O-Si bond-angle distribution in vitreous silica from first-principles 29Si NMR analysis

    International Nuclear Information System (INIS)

    Mauri, Francesco; Pasquarello, Alfredo; Pfrommer, Bernd G.; Yoon, Young-Gui; Louie, Steven G.

    2000-01-01

    The correlation between 29 Si chemical shifts and Si-O-Si bond angles in SiO 2 is determined within density-functional theory for the full range of angles present in vitreous silica. This relation closely reproduces measured shifts of crystalline polymorphs. The knowledge of the correlation allows us to reliably extract from the experimental NMR spectrum the mean (151 degree sign ) and the standard deviation (11 degree sign ) of the Si-O-Si angular distribution of vitreous silica. In particular, we show that the Mozzi-Warren Si-O-Si angular distribution is not consistent with the NMR data. This analysis illustrates the potential of our approach for structural determinations of silicate glasses. (c) 2000 The American Physical Society

  3. SI units in biomedical dosimetry

    International Nuclear Information System (INIS)

    Liden, K.

    1975-01-01

    The International commission on radiation units and measurements (ICRU), during the period from 1953 to 1962 presented its definitions of the quantities absorbed dose, exposure, activity, and dose equivalent and the corresponding special units the rad, the roentgen, the curie, and the rem. At the same time an international practical system of units was developed, Le Systeme International d'Unites (SI). It was adopted by the 11th Conference Generale des Poids et Mesures (CGPM) in 1960 and is now officially introduced in almost all countries. The general implementation of the SI means difficulties for the future use of the special radiation units, because the numerical factors involved prevent their adoption as SI units. In view of this, and after having sampled the opinion in the radiological field, the ICRU prepared a Statement on Units in July, 1974 which was forwarded to the Comite International des Poids et Mesures (CIPM) and its Comite Consultatif des Unites (CCU) for consideration. As a result of this statement the CIPM has now proposed, that the 15rh CGPM adopt special names for two SI units, namely the becquerel, symbol Bq, for the unit of activity of radionuclides equal to the reciprocal second, s 1- , and the gray, symbol Gy, for the unit of absorbed dose equal to the joule per kilogram, J/kg. The 15th CGPM will consider this matter in May, 1975. (author)

  4. Palladium transport in SiC

    International Nuclear Information System (INIS)

    Olivier, E.J.; Neethling, J.H.

    2012-01-01

    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 Pd 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.

  5. Palladium transport in SiC

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. La Mauritanie jusqu’au xxe siècle

    OpenAIRE

    Vanacker, Christiane

    2013-01-01

    De par sa situation, par les populations qu’elle rassemble, la République Islamique de Mauritanie apparaît en quelque sorte comme un trait d’union entre le monde maghrébin et le monde Noir. Cette vocation s’est précisée aux ixe-xie siècles mais c’est en fait toute l’histoire du pays qui est liée à celle de l’Afrique Méditerranéenne et de l’Afrique Occidentale. L’étude de l’évolution de la Mauritanie nous amène constamment à franchir le cadre strict des frontières qui sont les siennes à l’heur...

  7. Max Weber entre liberalismo y republicanismo

    Directory of Open Access Journals (Sweden)

    Villacañas Berlanga, José Luis

    2005-12-01

    Full Text Available This article attempts to analyze the differences between social democracy and political democracy as modern processes, as these were understood by Max Weber. The archetype of modernity resides, from this point of view, in a convergence of both processes, as occurred in countries like the USA and Great Britain. Weber's diagnosis is that, whereas social democracy can be organized around liberal arguments, political democracy cannot advance without republican concepts like those of virtue, rigour, responsability and representation. For Weber, these values could only become present in Germany thanks to an adequate and democratic reception of Nietzsche, and in some way this reception could make sense of the former's work.

    Este artículo pretende analizar las diferencias entre democracia social y democracia política como procesos modernos, tal y como fueron comprendidos por Max Weber. Lo arquetípico de la modernidad reside, desde este punto de vista, en una convergencia de ambos procesos, tal y como se dio en países como USA y Gran Bretaña. El diagnóstico de Weber es que, mientras la democracia social puede organizarse sobre argumentos liberales, la democracia política no puede avanzar sin conceptos republicanos como el de virtud, rigor, responsabilidad y representación. Para Weber, estos valores sólo podrían hacerse presentes en Alemania a partir de una recepción adecuada y democrática de Nietzsche y en cierto modo esta recepción daría sentido a su obra.

  8. Properties of SiMn slag as apozzolanic material in portland cement manufacture

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2005-12-01

    Full Text Available The primary purpose of this study was to evaluate the behaviour of SiMn slag as a pozzolanic material in commercial Portland cement manufacture. This necessitated exploring different scientific and technical aspects to ensure a correct valuation. The results obtained revealed that silica and calcium are the main components of SiMn slag, whose pozzolanic activity occupies an intermediate position between silica fume and fly ash; it reduces heat of hydration and mortars made with cement containing SiMn slag exhibit compressive strength values similar to the figures for standard mortar. Consequently, the use of SiMn slag as an active addition to cement is feasible, inasmuch as the resulting product meets the requirements laid down in the present legislation.

    El objetivo principal de este trabajo es evaluar el comportamiento de la escoria de SiMn como material puzolánico en la fabricación de cementos Portland comerciales. Para ello, resulta necesario investigar diferentes aspectos científicos y técnicos que conlleven a una correcta valorización de las mismas. Los resultados obtenidos en el presente trabajo han puesto de manifiesto que la escoria de SiMn presenta una naturaleza sílico-cálcica, actividad puzolúnica intermedia entre el humo de sílice y ceniza volante, reduce el calor de hidratación y los morteros con escoria de SiMn muestra alcanzan resistencias a compresión similares a las del mortero patrón. Por lo tanto, la utilización de la escoria de SiMn como adición activa al cemento es viable, cumpliendo con las exigencias recogidas en la norma vigente.

  9. La sociologie clinique entre psychanalyse et socioanalyse

    Directory of Open Access Journals (Sweden)

    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

  10. Las relaciones entre Chile y Suecia durante el primer gobierno de Olof Palme, 1969-1976

    Directory of Open Access Journals (Sweden)

    Fernando Camacho Padilla

    2014-06-01

    Full Text Available Durante el primer gobierno del socialdemócrata Olof Palme, las relaciones bilaterales entre Chile y Suecia fueron las más intensas de toda su historia, tanto en cercanía como en conflictividad. La razón la encontramos en los distintos fenómenos políticos que vivió Chile en ese periodo, puesto que Palme coincidió temporalmente con tres gobiernos claramente diferenciados: la Democracia Cristiana, la Unidad Popular y el Régimen Militar. Si las relaciones sueco-chilenas tuvieron su mejor momento durante el mandato de Salvador Allende, el golpe de Estado significó todo lo contrario. El compromiso que tuvo el embajador de Suecia, Harald Edelstam, por quienes eran perseguidos en Chile le llevó a su expulsión, lo que se tradujo en un claro deterioro de las relaciones y el inicio de una nueva etapa marcada por el gran contingente de exiliados que comenzaron a llegar a Suecia. Este trabajo analiza los principales acontecimientos diplomáticos ocurridos entre Chile y Suecia así como las consecuencias que tuvieron durante el gobierno de Olof Palme.

  11. CONSTRUÇÃO SOCIAL DE SENTIDOS SOBRE A RAVIDEZMATERNIDADE ENTRE ADOLESCENTES

    Directory of Open Access Journals (Sweden)

    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.

  12. Nivel de compromiso deportivo en tenistas y futbolistas entre 10 y 14 años

    Directory of Open Access Journals (Sweden)

    Paula Ortiz Marholz

    2011-12-01

    Full Text Available En el presente estudio se pretende determinar el nivel de compromiso deportivo en un grupo de tenistas y futbolistas, de manera de conocer si esta información puede ayudar a monitorear y controlar el entrenamiento deportivo, desde la perspectiva de la motivación de logro. La muestra está formada por 174 varones con edades comprendidas entre los 10 y 14 años, provenientes de las disciplinas deportivas de tenis (n=31 y fútbol (n=143. Los resultados mostraron un alto nivel de compromiso de los sujetos hacia su práctica deportiva, lo que se fundamenta en la relación existente entre los valores obtenidos por los distintos factores evaluados. Se concluye que estos deportistas exiben una disposición psicológica positiva que se refleja en el deseo y decisión de seguir participando en su respectiva disciplina deportiva, lo que se presenta como factor protector frente al abandono deportivo.

  13. O DESENVOLVIMENTO LOCAL INTEGRADO ENTRE AS CIDADES DE MACAPÁ E SANTANA (ESTADO DO AMAPÁ, BRASIL

    Directory of Open Access Journals (Sweden)

    José Alberto Tostes

    2016-06-01

    Full Text Available O presente artigo discute as relações estabelecidas entre as cidades de Macapá e Santana no estado do Amapá. Macapá e Santana juntas atuam como região indutora do desenvolvimento do Estado e influenciam as dinâmicas econômicas de um conjunto de ilhas do Pará e do interior do Amapá. Compõem as duas principais portas de entrada das atividades econômicas do Estado, o Aeroporto, localizado em Macapá, e o Porto, localizado em Santana. Também recebem influência e são estruturas indutoras e se conectam com a terceira porta de acesso ao Estado, à região de Fronteira do Oiapoque. As duas cidades articulam-se entre si por via rodoviária (Rodovia JK e Duca Serra e por via fluvial. Sendo Macapá considerada a porta aérea do Amapá, articula-se em uma relação multiescalar (regional, nacional e global.

  14. Advanced Optoelectronic Devices based on Si Quantum Dots/Si Nanowires Hetero-structures

    International Nuclear Information System (INIS)

    Xu, J; Zhai, Y Y; Cao, Y Q; Chen, K J

    2017-01-01

    Si quantum dots are currently extensively studied since they can be used to develop many kinds of optoelectronic devices. In this report, we review the fabrication of Si quantum dots (Si QD) /Si nanowires (Si NWs) hetero-structures by deposition of Si QDs/SiO 2 or Si QDs/SiC multilayers on Si NWs arrays. The electroluminescence and photovoltaic devices based on the formed hetero-structures have been prepared and the improved performance is confirmed. It is also found that the surface recombination via the surface defects states on the Si NWs, especially the ones obtained by the long-time etching, may deteriorate the device properties though they exhibit the better anti-reflection characteristics. The possible surface passivation approaches are briefly discussed. (paper)

  15. On formation of silicon nanocrystals under annealing SiO2 layers implanted with Si ions

    International Nuclear Information System (INIS)

    Kachurin, G.A.; Yanovskaya, S.G.; Volodin, V.A.; Kesler, V.G.; Lejer, A.F.; Ruault, M.-O.

    2002-01-01

    Raman scattering, X-ray photoelectron spectroscopy, and photoluminescence have been used to study the formation of silicon nanocrystals in SiO 2 implanted with Si ions. Si clusters have been formed at once in the postimplanted layers, providing the excessive Si concentration more ∼ 3 at. %. Si segregation with Si-Si 4 bonds formation is enhanced as following annealing temperature increase, however, the Raman scattering by Si clusters diminishes. The effect is explained by a transformation of the chain-like Si clusters into compact phase nondimensional structures. Segregation of Si nanoprecipitates had ended about 1000 deg C, but the strong photoluminescence typical for Si nanocrystals manifested itself only after 1100 deg C [ru

  16. Exposición a violencia entre los padres de adolescentes y adultos jóvenes víctimas de alguna conducta de maltrato en el noviazgo

    Directory of Open Access Journals (Sweden)

    César Armando Rey-Anacona

    2011-01-01

    Full Text Available Esta investigación tuvo como objetivo determinar si la exposición a violencia entre los padres podría relacionarse con el informe de haber sido objeto de algún tipo de maltrato por parte de la pareja en el noviazgo. Participaron 149 varones y 254 mujeres entre 15 y 35 años, solteros y sin hijos, comparándose los que informaron al menos una conducta maltratante con los que no, en relación con la exposición a violencia entre los padres. Se encontró que un porcentaje mayor de los participantes que informaron maltrato, presenciaron al menos un acto de violencia entre sus padres, comparado con el porcentaje de participantes que no reportaron maltrato, siendo esta relación más fuerte estadísticamente entre las mujeres que entre los varones y entre los adultos jóvenes que entre los adolescentes. Estos resultados señalan que dicha exposición podría facilitar la victimización y debería contemplarse en los programas de prevención.

  17. Nanocatalytic growth of Si nanowires from Ni silicate coated SiC nanoparticles on Si solar cell.

    Science.gov (United States)

    Parida, Bhaskar; Choi, Jaeho; Ji, Hyung Yong; Park, Seungil; Lim, Gyoungho; Kim, Keunjoo

    2013-09-01

    We investigated the nanocatalytic growth of Si nanowires on the microtextured surface of crystalline Si solar cell. 3C-SiC nanoparticles have been used as the base for formation of Ni silicate layer in a catalytic reaction with the Si melt under H2 atmosphere at an annealing temperature of 1100 degrees C. The 10-nm thick Ni film was deposited after the SiC nanoparticles were coated on the microtextured surface of the Si solar cell by electron-beam evaporation. SiC nanoparticles form a eutectic alloy surface of Ni silicate and provide the base for Si supersaturation as well as the Ni-Si alloy layer on Si substrate surface. This bottom reaction mode for the solid-liquid-solid growth mechanism using a SiC nanoparticle base provides more stable growth of nanowires than the top reaction mode growth mechanism in the absence of SiC nanoparticles. Thermally excited Ni nanoparticle forms the eutectic alloy and provides collectively excited electrons at the alloy surface, which reduces the activation energy of the nanocatalytic reaction for formation of nanowires.

  18. Research on a Micro-Nano Si/SiGe/Si Double Heterojunction Electro-Optic Modulation Structure

    Directory of Open Access Journals (Sweden)

    Song Feng

    2018-01-01

    Full Text Available The electro-optic modulator is a very important device in silicon photonics, which is responsible for the conversion of optical signals and electrical signals. For the electro-optic modulator, the carrier density of waveguide region is one of the key parameters. The traditional method of increasing carrier density is to increase the external modulation voltage, but this way will increase the modulation loss and also is not conducive to photonics integration. This paper presents a micro-nano Si/SiGe/Si double heterojunction electro-optic modulation structure. Based on the band theory of single heterojunction, the barrier heights are quantitatively calculated, and the carrier concentrations of heterojunction barrier are analyzed. The band and carrier injection characteristics of the double heterostructure structure are simulated, respectively, and the correctness of the theoretical analysis is demonstrated. The micro-nano Si/SiGe/Si double heterojunction electro-optic modulation is designed and tested, and comparison of testing results between the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation and the micro-nano Silicon-On-Insulator (SOI micro-ring electro-optic modulation, Free Spectrum Range, 3 dB Bandwidth, Q value, extinction ratio, and other parameters of the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation are better than others, and the modulation voltage and the modulation loss are lower.

  19. Effect of Ti and Si interlayer materials on the joining of SiC ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yang Il; Park, Jung Hwan; Kim, Hyun Gil; Park, Dong Jun; Park, Jeong Yong; Kim, Weon Ju [LWR Fuel Technology Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    SiC-based ceramic composites are currently being considered for use in fuel cladding tubes in light-water reactors. The joining of SiC ceramics in a hermetic seal is required for the development of ceramic-based fuel cladding tubes. In this study, SiC monoliths were diffusion bonded using a Ti foil interlayer and additional Si powder. In the joining process, a very low uniaxial pressure of ∼0.1 MPa was applied, so the process is applicable for joining thin-walled long tubes. The joining strength depended strongly on the type of SiC material. Reaction-bonded SiC (RB-SiC) showed a higher joining strength than sintered SiC because the diffusion reaction of Si was promoted in the former. The joining strength of sintered SiC was increased by the addition of Si at the Ti interlayer to play the role of the free Si in RB-SiC. The maximum joint strength obtained under torsional stress was ∼100 MPa. The joint interface consisted of TiSi{sub 2}, Ti{sub 3}SiC{sub 2}, and SiC phases formed by a diffusion reaction of Ti and Si.

  20. El lugar urbano deconstruido en correspondencias y congruencias entre mente–territorio–sociedad

    Directory of Open Access Journals (Sweden)

    Dr. Arq. Marcelo Zárate

    2012-11-01

    Full Text Available Desde el objetivo de desarrollar estrategias de conocimiento proyectual alternativas, de carácter sociofísico, dentro de un urbanismo focalizado sobre el ambiente del hombre, a partir de la premisa que considera a la ciudad como una compleja articulación de lugares (en sentido antropológico, se investiga una articulación estratégica entre las siguientes dimensiones esenciales del lugar con relación a los grupos sociales: las prácticas sociales; las significaciones de esas prácticas; los rasgos configurativos del escenario y la significación con que éstos y las prácticas sociales están cargados. La hipótesis fundamental establece que: según sea la configuración del esquema sociofísico-simbólico de articulación de estos elementos, o esquema genético del lugar, surgirán las claves para comprender si en un determinado lugar urbano están dadas o no las condiciones esenciales para desarrollar procesos participativos de planificación urbana ambiental. Con esta hipótesis, el trabajo fundamenta una respuesta posible sustentada en la articulación estratégica entre: congruencias sociofísicas (hacen referencia al nivel de adecuación de un determinado escenario para el despliegue sustentable de ciertas prácticas sociales, y correspondencias sociosimbólicas (hacen referencia a la coherencia entre las significaciones proyectadas desde distintos grupos humanos a partir de sus actividades asociadas a un escenario particular.

  1. Asociación entre enfermedad cardiovascular y anticuerpos contra Chlamydia pneumoniae

    Directory of Open Access Journals (Sweden)

    García-Elorriaga Guadalupe de los A

    2002-01-01

    Full Text Available Objetivo. Precisar si existe asociación entre enfermedad cardiovascular (ECV y anticuerpos contra Chlamydia en población mexicana. Material y métodos. Estudio transversal, realizado en la Unidad de Investigación en Inmunología e Infectología -Hospital de Infectología del Centro Médico Nacional La Raza (CMNR- y en el Servicio de Cirugía Cardiovascular y Asistencia Circulatoria, del Hospital General del CMNR, Instituto Mexicano del Seguro Social (IMSS, de agosto de 1998 a abril de 2000. Se determinaron anticuerpos IgG e IgM contra C. psittaci, C. trachomatis y C. pneumoniae mediante microinmunofluorescencia, en suero de 70 pacientes con ECV hospitalizados en el CMNR, mayores de 30 años, de uno u otro sexo, y se compararon con 140 sanos, pareados por edad y sexo. Se utilizaron muestras aleatorias simples, con un tamaño poblacional de 110, una prevalencia de 50% y un nivel de confianza de 99%. Para establecer la diferencia entre las proporciones de los títulos se utilizó ji cuadrada y se calculó la razón de momios. Resultados. El 94.3% (66/70 de los pacientes presentó IgG en contra de C. pneumoniae vs 37% (52/140 de los individuos sanos (p<0.001. Conclusiones. Existe una fuerte asociación entre anticuerpos IgG hacia C. pneumoniae y ECV.

  2. Estudo comparativo entre audiometria tonal limiar e resposta auditiva de estado estavel em normouvintes

    Directory of Open Access Journals (Sweden)

    Roberto Miquelino de Oliveira Beck

    2014-01-01

    Full Text Available Introdução: As respostas auditivas de estado estável permitem avaliar de forma objetiva limiares auditivos frequência-específica. A audiometria tonal é o exame padrão-ouro; no entanto, nem sempre pode ser conclusiva, principalmente em crianças e adultos não colaborativos. Objetivo: Comparar os limiares auditivos da RAEE aos da audiometria tonal em indivíduos com audição normal. Materiais e métodos: Foram incluídos neste estudo prospectivo de corte transversal 26 adultos (52 orelhas, de ambos os gêneros, com audiometria normal e sem queixas otológicas. Os pacientes foram submetidos a anamnese, otomicroscopia, audiometria e imitanciometria. A seguir, realizou-se avaliação de respostas auditivas de estado estável. Os resultados obtidos foram analisados estatisticamente e comparados entre si. Resultados: A diferença entre os limiares (em dB NA obtidos em ambos os exames para cada frequência testada foi de 7,12 dB para 500 Hz; 7,6 dB para 1000 Hz; 8,27 dB para 2000 Hz e 9,71 dB para 4000 Hz, com limiares mais elevados na RAEE, em todas as frequências. Não houve diferença estatística entre as médias para cada frequência testada. Conclusão: Os limiares obtidos na RAEE foram comparáveis aos da audiometria tonal em indivíduos normouvintes; entretanto, não deve ser usado como único método de avaliação auditiva.

  3. Ciberagresión entre adolescentes: prevalencia y diferencias de género

    Directory of Open Access Journals (Sweden)

    2017-01-01

    Full Text Available El presente trabajo tiene como objetivos analizar la prevalencia de la ciberagresión y la cibervictimización entre adolescentes en Asturias (España e identificar posibles diferencias de género. Para ello, fueron evaluados 3.175 adolescentes, de 12 a 18 años, seleccionados aleatoriamente de entre la población de estudiantes de Educación Secundaria Obligatoria de Asturias. Se aplicaron tres autoinformes: un cuestionario «ad hoc» sobre datos sociodemográficos y manejo de tecnologías de comunicación; el «Cuestionario de Ciberagresión para Adolescentes» (CYBA, para evaluar con qué frecuencia el adolescente evaluado reconoce haber ejercido diferentes conductas de ciberagresión durante los últimos tres meses; y el «Cuestionario de Cibervictimización para adolescentes» (CYVIC, para evaluar con qué frecuencia el adolescente reconoce haber sido víctima de diferentes tipos de ciberagresión en los últimos tres meses. Los resultados obtenidos muestran una prevalencia muy variable en función del tipo de ciberagresión o cibervictimización analizado. La ciberagresión verbal y la exclusión online son más habituales que la suplantación y la ciberagresión visual. Por lo general, no existen diferencias estadísticamente significativas entre chicos y chicas. En los casos en que existen, la tendencia general es que los chicos son más agresores que las chicas y las chicas más víctimas que los chicos, si bien las diferencias son pequeñas o muy pequeñas. Se discuten las implicaciones de estos resultados para la investigación futura y el tratamiento educativo del problema.

  4. Entrance channel excitations in the 28Si + 28Si reaction

    International Nuclear Information System (INIS)

    Decowski, P.; Gierlik, E.; Box, P.F.; Kamermans, R.; Nieuwenhuizen, G.J. van; Meijer, R.J.; Griffioen, K.A.; Wilschut, H.W.; Giorni, A.; Morand, C.; Demeyer, A.; Guinet, D.

    1991-01-01

    Velocity spectra of heavy ions produced in the 28 Si + 28 Si reaction at bombarding energies of 19.7 and 30 MeV/nucleon were measured and interpreted within the Q-optimum model extended by the inclusion of particle evaporation from excited fragments. Regions of forward angle spectra corresponding to the mutual excitation of the reaction partners with net mass transfer zero projected onto the Q-value variable show an enhancement at Q-values of -60 - -80 MeV (excitation energies of the reaction partners equal to 30 - 40 MeV). This energy range coincides with the region of 2ℎω - 3ℎω excitations characteristic for giant osciallations. This selective excitation, which occurs at a very early stage of the reaction (the cross section is the largest at very forward angles), provides an important doorway to other dissipative processes

  5. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Oxide Structure Dependence of SiO2/SiOx/3C-SiC/n-Type Si Nonvolatile Resistive Memory on Memory Operation Characteristics

    Science.gov (United States)

    Yamaguchi, Yuichiro; Shouji, Masatsugu; Suda, Yoshiyuki

    2012-11-01

    We have investigated the dependence of the oxide layer structure of our previously proposed metal/SiO2/SiOx/3C-SiC/n-Si/metal metal-insulator-semiconductor (MIS) resistive memory device on the memory operation characteristics. The current-voltage (I-V) measurement and X-ray photoemission spectroscopy results suggest that SiOx defect states mainly caused by the oxidation of 3C-SiC at temperatures below 1000 °C are related to the hysteresis memory behavior in the I-V curve. By restricting the SiOx interface region, the number of switching cycles and the on/off current ratio are more enhanced. Compared with a memory device formed by one-step or two-step oxidation of 3C-SiC, a memory device formed by one-step oxidation of Si/3C-SiC exhibits a more restrictive SiOx interface with a more definitive SiO2 layer and higher memory performances for both the endurance switching cycle and on/off current ratio.

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

    Directory of Open Access Journals (Sweden)

    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

  8. Laser-controlled stress of Si nanocrystals in a free-standing Si /SiO2 superlattice

    Science.gov (United States)

    Khriachtchev, Leonid; Räsänen, Markku; Novikov, Sergei

    2006-01-01

    We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar+ laser radiation melts Si nanocrystals in a free-standing Si /SiO2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means.

  9. Laser-controlled stress of Si nanocrystals in a free-standing Si/SiO2 superlattice

    International Nuclear Information System (INIS)

    Khriachtchev, Leonid; Raesaenen, Markku; Novikov, Sergei

    2006-01-01

    We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar + laser radiation melts Si nanocrystals in a free-standing Si/SiO 2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3 GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means

  10. Gas leak tightness of SiC/SiC composites at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hayasaka, Daisuke, E-mail: hayasaka@oasis.muroran-it.ac.jp [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Park, Joon-Soo. [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE-SiC/SiC has extremely densified microstructure compared with other SiC/SiC composite like CVI. • Excellent helium and hydrogen gas-leak tightness of SiC/SiC composites by DEMO-NITE method from prototype industrialization production line was presented. • The excellence against stainless steel and Zircaloy at elevated temperature, together with generic excellent properties of SiC will be inevitable for innovative blanket and divertors for DEMO- and power- fusion reactors. - Abstract: SiC/SiC composite materials are attractive candidates for high heat flux components and blanket of fusion reactor, mainly due to their high temperature properties, radiation damage tolerance and low induced radioactivity. One of the challenges for SiC/SiC application in fusion reactors is to satisfy sufficient gas leak tightness of hydrogen and helium isotopes. Although many efforts have been carried-out, SiC/SiC composites by conventional processes have not been successful to satisfy the requirements, except SiC/SiC composites by NITE-methods. Toward the early realization of SiC/SiC components into fusion reactor systems process development of NITE-process has been continued. Followed to the brief introduction of recently developed DEMO-NITE process, baseline properties and hydrogen and helium gas leak tightness is presented. SiC/SiC claddings with 10 mm in diameter and 1 mm in wall thickness are tested by gas leak tightness system developed. The leak tightness measurements are done room temperature to 400 °C. Excellent gas leak tightness equivalent or superior to Zircaloy claddings for light water fission reactors is confirmed. The excellent gas leak tightness suggests nearly perfect suppression of large gas leak path in DEMO-NITE SiC/SiC.

  11. 3C-SiC nanocrystal growth on 10° miscut Si(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Deokar, Geetanjali, E-mail: gitudeo@gmail.com [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); D' Angelo, Marie; Demaille, Dominique [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Cavellin, Catherine Deville [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Faculté des Sciences et Technologie UPEC, 61 av. De Gaulle, Créteil F-94010 (France)

    2014-04-01

    The growth of 3C-SiC nano-crystal (NC) on 10° miscut Si(001) substrate by CO{sub 2} thermal treatment is investigated by scanning and high resolution transmission electron microscopies. The vicinal Si(001) surface was thermally oxidized prior to the annealing at 1100 °C under CO{sub 2} atmosphere. The influence of the atomic steps at the vicinal SiO{sub 2}/Si interface on the SiC NC growth is studied by comparison with the results obtained for fundamental Si(001) substrates in the same conditions. For Si miscut substrate, a substantial enhancement in the density of the SiC NCs and a tendency of preferential alignment of them along the atomic step edges is observed. The SiC/Si interface is abrupt, without any steps and epitaxial growth with full relaxation of 3C-SiC occurs by domain matching epitaxy. The CO{sub 2} pressure and annealing time effect on NC growth is analyzed. The as-prepared SiC NCs can be engineered further for potential application in optoelectronic devices and/or as a seed for homoepitaxial SiC or heteroepitaxial GaN film growth. - Highlights: • Synthesis of 3C-SiC nanocrystals epitaxied on miscut-Si using a simple technique • Evidence of domain matching epitaxy at the SiC/Si interface • SiC growth proceeds along the (001) plane of host Si. • Substantial enhancement of the SiC nanocrystal density due to the miscut • Effect of the process parameters (CO{sub 2} pressure and annealing duration)

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

    International Nuclear Information System (INIS)

    Kohyama, Akira; Kishimoto, Hirotatsu

    2015-01-01

    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)

  13. Growth of CoSi2 on Si(001) by reactive deposition epitaxy

    International Nuclear Information System (INIS)

    Lim, C.W.; Shin, C.-S.; Gall, D.; Zuo, J.M.; Petrov, I.; Greene, J.E.

    2005-01-01

    CaF 2 -structure CoSi 2 layers were formed on Si(001) by reactive deposition epitaxy (RDE) and compared with CoSi 2 layers obtained by conventional solid phase growth (SPG). In both sets of experiments, Co was deposited by ultrahigh-vacuum magnetron sputtering and CoSi 2 formed at 600 deg. C. However, in the case of RDE, CoSi 2 formation occurred during Co deposition while for SPG, Co was deposited at 25 deg. C and silicidation took place during subsequent annealing. X-ray diffraction pole figures and transmission electron microscopy results demonstrate that RDE CoSi 2 layers are epitaxial with a cube-on-cube relationship (001) CoSi 2 parallel (001) Si and [100] CoSi 2 parallel[100] Si . In contrast, SPG films are polycrystalline with an average grain size of ≅1000 A and a mixed 111/002/022/112 orientation. We attribute the striking difference to rapid Co diffusion into the Si(001) substrate during RDE for which the high Co/Si reactivity gives rise to a flux-limited reaction resulting in the direct formation of the disilicide phase. In contrast, sequential nucleation and transformation among increasingly Si-rich phases--from orthorhombic Co 2 Si to cubic CoSi to CoSi 2 --during SPG results in polycrystalline layers with a complex texture

  14. High resolution investigation of the 30Si(þ, þ)30Si reaction

    NARCIS (Netherlands)

    Walinga, J.; Rinsvelt, H.A. van; Endt, P.M.

    The differential cross section for elastic scattering of protons on 30Si was measured with surface barrier counters at four angles. Thirty-six 30Si(þ, γ)31P resonances are known in the Ep=1–2MeV region. Fifteen of these were also observed in the 30Si(þ, þ)30Si reaction, with natural widths varying

  15. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo; Yoo, Tae Jin; Kim, Jin Tae; Pak, Yusin; Kumaresan, Yogeenth; Kim, Hyeonghun; Kim, Woochul; Lee, Byoung Hun; Jung, Gun Young

    2018-01-01

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates

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

    NARCIS (Netherlands)

    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

  17. USO DE TABACO ENTRE ADOLESCENTES: REVISÃO DE LITERATURA

    OpenAIRE

    Amanda Márcia dos Santos Reinaldo; Camila Cesar Goecking; Jennifer Perucci de Almeida; Yasmin Narciso Goulart

    2010-01-01

    Revisión sistemática de la literatura sobre el uso de tabaco entre adolescentes. La utilización del tabaco entre adolescentes, en general, puede estar asociada al éxito, a la necesidad de aceptación, a cuestiones familiares, entre otros factores que incentivan de cierta forma a su uso. Las políticas de salud para el área trabajan para prevenir y reducir el consumo, alertando en relación al riesgo al que tal población se expone cuando utiliza tabaco. Conocer el perfil de los adolescentes que u...

  18. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

  19. L' Aroumain entre dialecte et langue

    Directory of Open Access Journals (Sweden)

    Momčilo D. Savić

    1987-12-01

    Full Text Available A vant d' essayer à repondre à la question que nous avons posée et qui représente l'objet central de notre expose d'aujourd'hui, nous considérons opportun d'envisager un peu plus amplement le problème en intégrité mettant en relief aussi sa dimension historique, parce que nous savons très bien que toute solution n'est que partielle si elle ne tient pas compte de la réalité historique. D'autre part, il est aussi nécessaire de s'arrêter plus à long sur la préhistoire du problème parce que nous nous occupons d'une des questions périphériques de la Romània Orientale. En disant "question périphérique", je désire souligner que l'intérêt des romanisants est attaché aux langues romanes qui possèdent une langue traditionnelle en écrit, qui sont nationales et représentent la langue d'une formation politique, c'est-à-dire de l'autorité d'Etat. Nous savons aussi qu'il y a en Occident un intérêt bien limité pour les langues et les groupes linguistiques qui ne sont pas représentants de l'autorité d'Etat, tandis que, d'autre côté, quand nous parlons aujourd'hui de la romanité orientale, nous avons en vue en premier lieu la langue roumaine littéraire, sa littérature, ainsi que la culture exprimée dans cette langue. Quant à l'aroumain, l'intérêt qu'il suscite est assez limité, soit comme dialecte soit comme langue, ce qui reste au centre de notre attention.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    Ping Wang, Y.; 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.; Stodolna, J.; Ponchet, A.; Bahri, M.; Largeau, L.; Patriarche, G.; Magen, C.

    2015-01-01

    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

  2. Si quantum dot structures and their applications

    Science.gov (United States)

    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.

  3. Ion beam processes in Si

    International Nuclear Information System (INIS)

    Holland, O.W.; Narayan, J.; Fathy, D.

    1984-07-01

    Observation of the effects of implants of energetic ions at high dose rates into Si have produced some exciting and interesting results. The mechanism whereby displacement damage produced by ions self-anneals during high dose rate implantation is discussed. It is shown that ion beam annealing (IBA) offers in certain situations unique possibilities for damage annealing. Annealing results of the near surface in Si with a buried oxide layer, formed by high dose implantation, are presented in order to illustrate the advantages offered by IBA. It is also shown that ion irradiation can stimulate the epitaxial recrystallization of amorphous overlayers in Si. The nonequilibrium alloying which results from such epitaxial processes is discussed as well as mechanisms which limit the solid solubility during irradiation. Finally, a dose rate dependency for the production of stable damage by ion irradiation at a constant fluence has been observed. For low fluence implants, the amount of damage is substantially greater in the case of high flux rather than low flux implantation

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

    NARCIS (Netherlands)

    Dobrovolskiy, S.; Yakshin, Andrey; Tichelaar, F.D.; Verhoeven, J.; Louis, Eric; Bijkerk, Frederik

    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

  5. Stability analysis of SiO2/SiC multilayer coatings

    International Nuclear Information System (INIS)

    Fu Zhiqiang; Jean-Charles, R.

    2006-01-01

    The stability behaviours of SiC coatings and SiO 2 /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 T cp of SiC depends is the partial pressure of oxidative impurities; T cp 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 T cs of SiO 2 are both the partial pressure of impurities and the amount of impurities for l mol SiO 2 ; T cs of SiO 2 increases with the partial pressure of oxidative impurities at the same amount of the impurities for 1 mol SiO 2 while it decreases with the amount of the impurities for 1 mm SiO 2 at the same partial pressure of the impurities. The influence of other impurities on T cp of SiC in He-O 2 is studied and it is found that CO 2 , H 2 O and N-2 increase T cp of SiC in He-O 2 while H 2 , CO and CH 4 decrease T cp of SiC He-O 2 . When there exist both oxidative impurities and reductive impurities, their effect on T cs of SiO 2 can be suppressed by the other. In HTR-10 operation atmosphere, SiO 2 /SiC coatings can keep stable status at higher temperature than SiC coatings, so SiO 2 /SiC coatings is more suitable to improve the oxidation resistance of graphite in HTR-10 operation atmosphere compared with SiC coatings. (authors)

  6. (113) Facets of Si-Ge/Si Islands; Atomic Scale Simulation

    Science.gov (United States)

    Kassem, Hassan

    We have studied, by computer simulation, some static and vibrationnal proprieties of SiGe/Si islands. We have used a Valence Force Field combined to Monte Carlo technique to study the growth of Ge and SiGe on (001)Si substrates. We have focalised on the case of large pyramidal islands presenting (113) facets on the free (001)Si surface with various non uniform composition inside the islands. The deformation inside the islands and Raman spectroscopy are discussed.

  7. 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

    Directory of Open Access Journals (Sweden)

    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

  8. Porous SiC/SiC composites development for industrial application

    International Nuclear Information System (INIS)

    Maeta, S.; Hinoki, T.

    2014-01-01

    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

  9. Double transparent conducting layers for Si photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Ju-Hyung [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Kim, Joondong, E-mail: joonkim@incheon.ac.kr [Department of Electrical Engineering, Incheon National University, Incheon, 406772 (Korea, Republic of); Park, Yun Chang [Measurement and Analysis Division, National Nanofab Center (NNFC), Daejeon 305806 (Korea, Republic of); Moon, Sang-Jin [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); Anderson, Wayne A. [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States)

    2013-11-29

    Double transparent conductive oxide (TCO) film-embedded Si heterojunction solar cells were fabricated. An intentional doping was not applied for heterojunction solar cells due to the spontaneous Schottky junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedded Si (ITO/AZO/Si) heterojunction solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si (ITO/Si or AZO/Si) devices due to the optical and the electrical benefits. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme for an effective TCO film-embedded heterojunction Si solar cell. - Highlights: • Double transparent conducting oxide films form a heterojunction to Si. • A quality indium-tin-oxide film was grown above an Al-doped zinc oxide template. • Heterojunction Si solar cell was made without an intentional doping process.

  10. Dynamic behaviors of laser ablated Si particles

    International Nuclear Information System (INIS)

    Ohyanagi, T.; Murakami, K.; Miyashita, A.; Yoda, O.

    1995-01-01

    The dynamics of laser-ablated Si particles produced by laser ablation have been investigated by time-and-space resolved X-ray absorption spectroscopy in a time scale ranging from 0 ns to 120 ns with a time resolution of 10 ns. Neutral and charged particles are observed through all X-ray absorption spectra. Assignments of transitions from 2s and 2p initial states to higher Rydberg states of Si atom and ions are achieved, and we experimentally determine the L II,III absorption edges of neutral Si atom (Si 0 ) and Si + , Si 2+ , Si 3+ and Si 4+ ions. The main ablated particles are found to be Si atom and Si ions in the initial stage of 0 ns to 120 ns. The relative amounts depend strongly on times and laser energy densities. We find that the spatial distributions of particles produced by laser ablation are changed with supersonic helium gas bombardment, but no cluster formation takes place. This suggests that a higher-density region of helium gas is formed at the top of the plume of ablated particles, and free expansion of particles is restrained by this helium cloud, and that it takes more than 120 ns to form Si clusters. (author)

  11. Double transparent conducting layers for Si photovoltaics

    International Nuclear Information System (INIS)

    Yun, Ju-Hyung; Kim, Joondong; Park, Yun Chang; Moon, Sang-Jin; Anderson, Wayne A.

    2013-01-01

    Double transparent conductive oxide (TCO) film-embedded Si heterojunction solar cells were fabricated. An intentional doping was not applied for heterojunction solar cells due to the spontaneous Schottky junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedded Si (ITO/AZO/Si) heterojunction solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si (ITO/Si or AZO/Si) devices due to the optical and the electrical benefits. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme for an effective TCO film-embedded heterojunction Si solar cell. - Highlights: • Double transparent conducting oxide films form a heterojunction to Si. • A quality indium-tin-oxide film was grown above an Al-doped zinc oxide template. • Heterojunction Si solar cell was made without an intentional doping process

  12. Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures

    International Nuclear Information System (INIS)

    Varzgar, John B.; Kanoun, Mehdi; Uppal, Suresh; Chattopadhyay, Sanatan; Tsang, Yuk Lun; Escobedo-Cousins, Enrique; Olsen, Sarah H.; O'Neill, Anthony; Hellstroem, Per-Erik; Edholm, Jonas; Ostling, Mikael; Lyutovich, Klara; Oehme, Michael; Kasper, Erich

    2006-01-01

    The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q ox ) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10 4 s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10 5 s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q inj ) compared to Q inj in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10 4 s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si

  13. Innovative SiC/SiC composite for nuclear applications

    International Nuclear Information System (INIS)

    Chaffron, L.; Sauder, C.; Lorrette, C.; Briottet, L.; Michaux, A.; Gelebart, L.; Coupe, A.; Zabiego, M.; Le Flem, M.; Seran, J. L.

    2013-01-01

    Among various refractory materials, SiC/SiC ceramic matrix composites (CMC) are of prime interest for fusion and advanced fission energy applications, due to their excellent irradiation tolerance and safety features (low activation, low tritium permeability,K). Initially developed as fuel cladding materials for the Fourth generation Gas cooled Fast Reactor (GFR), this material has been recently envisaged by CEA for different core structures of Sodium Fast Reactor (SFR) which combines fast neutrons and high temperature (500 deg.C). Regarding fuel cladding generic application, in the case of GFR, the first challenge facing this project is to demonstrate the feasibility of a fuel operating under very harsh conditions that are (i) temperatures of structures up to 700 deg.C in nominal and over 1600 deg.C in accidental conditions, (ii) irradiation damage higher than 60 dpa SiC , (iii) neutronic transparency, which disqualifies conventional refractory metals as structural core materials, (iv) mechanical behavior that guarantees in most circumstances the integrity of the first barrier (e.g.: ε> 0.5%), which excludes monolithic ceramics and therefore encourages the development of new types of fibrous composites SiC/SiC adapted to the fast reactor conditions. No existing material being capable to match all these requirements, CEA has launched an ambitious program of development of an advanced material satisfying the specifications [1]. This project, that implies many laboratories, inside and outside CEA, has permitted to obtain a very high quality compound that meets most of the challenging requirements. We present hereinafter few recent results obtained regarding the development of the composite. One of the most relevant challenges was to make a gas-tight composite up to the ultimate rupture. Indeed, multi-cracking of the matrix is the counterpart of the damageable behavior observed in these amazing compounds. Among different solutions envisaged, an innovative one has been

  14. Diferencias entre la sensibilidad paterna según variables sociodemográficas

    Directory of Open Access Journals (Sweden)

    Lilliana Nieri

    2017-06-01

    Full Text Available Durante décadas, diversas investigaciones sostuvieron que la función del padre era la de proveedor económico. No obstante, con los cambios históricos que fueron sucediendo en las últimas décadas, muchos psicólogos se interesaron en conocer cuáles eran las funciones del padre y qué le ocurría durante la gestación de su hijo. Igualmente, se ha comprobado que las características socioculturales y sociodemográficas del padre influyen en el ejercicio y la transición hacia la paternidad. Por ello, esta investigación se centró en analizar si existen diferencias entre los sentimientos, las emociones y las reacciones de los padres durante la gestación y el nacimiento de su hijo con las variables sociodemográficas: edad paterna, niveles de estudio, estado civil, situación laboral, cantidad de hijos, edad de su hijo y sexo de su hijo. La muestra de este estudio estuvo compuesta por 170 padres con hijos menores de dos años de edad. El diseño de estudio fue no experimental, de tipo descriptivo. Los instrumentos que se utilizaron fueron: cuestionario de sensibilidad paterna y una encuesta sociodemográfica diseñada para dicha investigación. Los resultados demuestran que existen diferencias entre la sensibilidad del padre con respecto a la edad del padre, la edad del hijo y el nivel de estudios paternos, y no se encontraron diferencias entre esta y el estado civil, situación laboral, cantidad de hijos y sexo de los hijos. A modo de conclusión, la construcción y el desarrollo de la paternidad dependen de diversas variables tales como el contexto social y cultural, su situación actual, entre otros y la conjunción de todas determinan la manera en que el padre se vincule con su hijo.

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

    International Nuclear Information System (INIS)

    Asoka-Kumar, P.; Lynn, K.G.

    1993-01-01

    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

  16. MuSiK Projekt:Multimaterialdruck von C/Si/SiC-Keramiken

    OpenAIRE

    Marigo, Gloria; Wahl, Larissa; Nauditt, Gotthard

    2017-01-01

    Poster über den ersten 6 Monate von MuSiK Projekt. Additive Verfahren wurden ursprünglich zur effizienten Herstellung von Mustern und Prototypen entwickelt und bieten besondere Einsatzpotentiale, die mittlerweile auch für die Kleinserienproduktion hochinteressant sind. Im Bereich der keramischen Komponenten ist der Einsatz additiver Verfahren bislang nicht weit verbreitet. Ein Grund dafür ist unter anderem die eingeschränkte Verfügbarkeit der notwendigen Fertigungsanlagen und entsprech...

  17. Formation, structure, and phonon confinement effect of nanocrystalline Si1-xGex in SiO2-Si-Ge cosputtered films

    International Nuclear Information System (INIS)

    Yang, Y.M.; Wu, X.L.; Siu, G.G.; Huang, G.S.; Shen, J.C.; Hu, D.S.

    2004-01-01

    Using magnetron cosputtering of SiO 2 , Ge, and Si targets, Si-based SiO 2 :Ge:Si films were fabricated for exploring the influence of Si target proportion (P Si ) and annealing temperature (Ta) on formation, local structure, and phonon properties of nanocrystalline Si 1-x Ge x (nc-Si 1-x Ge x ). At low P Si and Ta higher than 800 deg. C, no nc-Si 1-x Ge x but a kind of composite nanocrystal consisting of a Ge core, GeSi shell, and amorphous Si outer shell is formed in the SiO 2 matrix. At moderate P Si , nc-Si 1-x Ge x begins to be formed at Ta=800 deg. C and coexists with nc-Ge at Ta=1100 deg. C. At high P Si , it was disclosed that both optical phonon frequency and lattice spacing of nc-Si 1-x Ge x increase with raising Ta. The possible origin of this phenomenon is discussed by considering three factors, the phonon confinement, strain effect, and composition variation of nc-Si 1-x Ge x . This work will be helpful in understanding the growth process of ternary GeSiO films and beneficial to further investigations on optical properties of nc-Ge 1-x Si x in the ternary matrix

  18. Oxidation protection of multilayer CVD SiC/B/SiC coatings for 3D C/SiC composite

    International Nuclear Information System (INIS)

    Liu Yongsheng; Cheng Laifei; Zhang Litong; Wu Shoujun; Li Duo; Xu Yongdong

    2007-01-01

    A CVD boron coating was introduced between two CVD SiC coating layers. EDS and XRD results showed that the CVD B coating was a boron crystal without other impurity elements. SEM results indicated that the CVD B coating was a flake-like or column-like crystal with a compact cross-section. The crack width in the CVD SiC coating deposited on CVD B is smaller than that in a CVD SiC coating deposited on CVD SiC coating. After oxidation at 700 deg. C and 1000 deg. C, XRD results indicated that the coating was covered by product B 2 O 3 or B 2 O 3 .xSiO 2 film. The cracks were sealed as observed by SEM. There was a large amount of flake-like material on hybrid coating surface after oxidation at 1300 deg. C. Oxidation weight loss and residual flexural strength results showed that hybrid SiC/B/SiC multilayer coating provided better oxidation protection for C/SiC composite than a three layer CVD SiC coating at temperatures from 700 deg. C to 1000 deg. C for 600 min, but worse oxidation protection above 1000 deg. C due to the large amount of volatilization of B 2 O 3 or B 2 O 3 .xSiO 2

  19. Mechanical behavior of SiCf/SiC composites with alternating PyC/SiC multilayer interphases

    International Nuclear Information System (INIS)

    Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

    2013-01-01

    Highlights: ► Superior combination of flexural strength and fracture toughness of the 3D SiC/SiC composite was achieved by interface tailoring. ► Resulted composite possesses a much higher flexural strength and fracture toughness than its counterparts in literatures. ► Mechanisms that PyC/SiC multilayer coatings improve the mechanical properties were illustrated. -- Abstract: In order to tailor the fiber–matrix interface of continuous silicon carbide fiber reinforced silicon carbide (SiC f /SiC) composites for improved fracture toughness, alternating pyrolytic carbon/silicon carbide (PyC/SiC) multilayer coatings were applied to the KD-I SiC fibers using chemical vapor deposition (CVD) method. Three dimensional (3D) KD-I SiC f /SiC composites reinforced by these coated fibers were fabricated using a precursor infiltration and pyrolysis (PIP) process. The interfacial characteristics were determined by the fiber push-out test and microstructural examination using scanning electron microscopy (SEM). The effect of interface coatings on composite mechanical properties was evaluated by single-edge notched beam (SENB) test and three-point bending test. The results indicate that the PyC/SiC multilayer coatings led to an optimum interfacial bonding between fibers and matrix and greatly improved the fracture toughness of the composites.

  20. An Isotope Study of Hydrogenation of poly-Si/SiOx Passivated Contacts for Si Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, Manuel; Nemeth, William; van de Loo, Bas, W.H.; Macco, Bart; Kessels, Wilhelmus, M.M.; Stradins, Paul; Young, David, L.

    2017-06-26

    For many years, the record Si solar cell efficiency stood at 25.0%. Only recently have several companies and institutes managed to produce more efficient cells, using passivated contacts of made doped poly-Si or a-Si:H and a passivating intrinsic interlayer in all cases. Common to these designs is the need to passivate the layer stack with hydrogen. In this contribution, we perform a systematic study of passivated contact passivation by hydrogen, using poly-Si/SiOx passivated contacts on n-Cz-Si, and ALD Al2O3 followed by a forming gas anneal (FGA) as the hydrogen source. We study p-type and n-type passivated contacts with implied Voc exceeding 690 and 720 mV, respectively, and perform either the ALD step or the FGA with deuterium instead of hydrogen in order to separate the two processes via SIMS. By examining the deuterium concentration at the SiOx in both types of samples, we demonstrate that the FGA supplies negligible hydrogen species to the SiOx, regardless of whether the FGA is hydrogenated or deuterated. Instead, it supplies the thermal energy needed for hydrogen species in the Al2O3 to diffuse there. Furthermore, the concentration of hydrogen species at the SiOx can saturate while implied Voc continues to increase, showing that the energy from the FGA is also required for hydrogen species already at the SiOx to find recombination-active defects to passivate.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. RELACIÓN ENTRE DECISIONES ARBITRALES Y VARIABLES DEPORTIVAS EN EL FÚTBOL PROFESIONAL DE COSTA RICA

    Directory of Open Access Journals (Sweden)

    María Clara Rodríguez

    2002-12-01

    Full Text Available Con el objetivo de determinar objetivamente si existen algunas tendencias en los juicios arbitrales del fútbol costarricense, específicamente en cuanto a amonestaciones y expulsiones, se analizaron 575 partidos de primera y segunda división jugados durante los años 2001 y 2002, a partir de los informes arbitrales oficiales. Se confirmó la hipótesis de la ventaja para el equipo local, así como la tendencia a compensar las sanciones entre los equipos contrincantes, especialmente con respecto a las expulsiones; no hubo diferencias en función del nivel de los árbitros, ni se evidenciaron sesgos en función de los equipos. Se hallaron diferencias significativas individuales entre los árbitros. También se encontraron diferencias significativas para tarjetas rojas (TA y tarjetas amarillas (TR entre primer y segundo tiempo, y con relación al número total de goles marcados. En conclusión, se observó mayor discriminación en las decisiones arbitrales frente a las TR y mayor homogeneidad frente a las TA.

  3. Variación en loci isoenzimáticos entre machos y hembras de Lutzomyia shannoni (Dyar (Diptera: Psychodidae de Colombia

    Directory of Open Access Journals (Sweden)

    Estrella Cárdenas

    2000-12-01

    Full Text Available Se analizaron por sexo poblaciones silvestres de Lutzomyia shannoni de tres localidades distantes entre si: Palambi (Nariño, Cimitarra (Santander y Chinácota (Norte de Santander, con el fin de establecer la variación en 11 isoenzimas. Estas muestras se compararon con ejemplares de una colonia mantenida en el Laboratorio de Entomologia del INS desde 1992. Se utilizó el sistema de electroforesis vertical en geles de poliacrilarnida al 6%. Se encontró una heterocigosidad promedio entre 18.5 y 24,7% en las hembras silvestres y entre 13,5 y 19.4% entre los machos silvestres. La heterocigosidad promedio en las hembras de la colonia fue de 14,8% mientras que en los machos fue de 20.1%. Se detectaron entre 2,0 y 2,5 alelos por locus. La distancia genética de Nei entre las poblaciones fue baja y osciló entre 0,005 y 0,073. En la muestra de la colonia de 79 individuos. el locus Gpifue homocigoto en todas las hembras y heterocigoto en todos los machos. Aunque esta observación es probablemente una consecuencia de la colonización, indica que el locus Gpi está fuertemente unido a los cromosomas que determinan el sexo, con el alelo Gpi0,62 unido al locus que determina hembras y el alelo Gpi0,72 asociado con el locus que determina machos.

  4. Determination of optimum Si excess concentration in Er-doped Si-rich SiO2 for optical amplification at 1.54 μm

    International Nuclear Information System (INIS)

    Savchyn, Oleksandr; Coffey, Kevin R.; Kik, Pieter G.

    2010-01-01

    The presence of indirect Er 3+ excitation in Si-rich SiO 2 is demonstrated for Si-excess concentrations in the range of 2.5-37 at. %. The Si excess concentration providing the highest density of sensitized Er 3+ ions is demonstrated to be relatively insensitive to the presence of Si nanocrystals and is found to be ∼14.5 at. % for samples without Si nanocrystals (annealed at 600 deg. C) and ∼11.5 at. % for samples with Si nanocrystals (annealed at 1100 deg. C). The observed optimum is attributed to an increase in the density of Si-related sensitizers as the Si concentration is increased, with subsequent deactivation and removal of these sensitizers at high Si concentrations. The optimized Si excess concentration is predicted to generate maximum Er-related gain at 1.54 μm in devices based on Er-doped Si-rich SiO 2 .

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

    KAUST Repository

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

    Science.gov (United States)

    Liliental-Weber, Zuzanna [El Sobrante, CA; Maltez, Rogerio Luis [Porto Alegre, BR; Morkoc, Hadis [Richmond, VA; Xie, Jinqiao [Raleigh, VA

    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.

  7. Comparative study of anisotropic superconductivity in CaAlSi and CaGaSi

    International Nuclear Information System (INIS)

    Tamegai, T.; Uozato, K.; Kasahara, S.; Nakagawa, T.; Tokunaga, M.

    2005-01-01

    In order to get some insight into the origin of the anomalous angular dependence of H c2 in a layered intermetallic compound CaAlSi, electronic, superconducting, and structural properties are compared between CaAlSi and CaGaSi. The angular dependence of H c2 in CaGaSi is well described by the anisotropic GL model. Parallel to this finding, the pronounced lattice modulation accompanying the superstructure along the c-axis in CaAlSi is absent in CaGaSi. A relatively large specific heat jump at the superconducting transition in CaAlSi compared with CaGaSi indicates the presence of strong electron-phonon coupling in CaAlSi, which may cause the superstructure and the anomalous angular dependence of H c2

  8. Switching Performance Evaluation of Commercial SiC Power Devices (SiC JFET and SiC MOSFET) in Relation to the Gate Driver Complexity

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    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. Interfacial stability of CoSi2/Si structures grown by molecular beam epitaxy

    Science.gov (United States)

    George, T.; Fathauer, R. W.

    1992-01-01

    The stability of CoSi2/Si interfaces was examined in this study using columnar silicide structures grown on (111) Si substrates. In the first set of experiments, Co and Si were codeposited using MBE at 800 C and the resulting columnar silicide layer was capped by epitaxial Si. Deposition of Co on the surface of the Si capping layer at 800 C results in the growth of the buried silicide columns. The buried columns grow by subsurface diffusion of the deposited Co, suppressing the formation of surface islands of CoSi2. The column sidewalls appear to be less stable than the top and bottom interfaces, resulting in preferential lateral growth and ultimately in the coalescence of the columns to form a continuous buried CoSi2 layer. In the second set of experiments, annealing of a 250 nm-thick buried columnar layer at 1000 C under a 100 nm-thick Si capping layer results in the formation of a surface layer of CoSi2 with a reduction in the sizes of the CoSi2 columns. For a sample having a thicker Si capping layer the annealing leads to Ostwald ripening producing buried equiaxed columns. The high CoSi2/Si interfacial strain could provide the driving force for the observed behavior of the buried columns under high-temperature annealing.

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

    OpenAIRE

    Sapin, Christian

    2010-01-01

    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...

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

    Directory of Open Access Journals (Sweden)

    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...

  12. O professor que cativa: entre a narrativa da história e o cuidado de si

    OpenAIRE

    Marcello Paniz Giacomoni

    2016-01-01

    O presente artigo apresenta e discute os primeiros passos da pesquisa “Ensino de História e narrativas: o professor e a persuasão em sala de aula”, desenvolvida no Programa de Pós Graduação de Educação da UFRGS, em nível de doutorado, sob orientação do Prof. Dr. Fernando Seffner. Partindo de uma reflexão sobre o Ensino de História e analisando o caráter narrativo da história, passando por autores como Hayden White, Peter Gay, Jörn Rüsen, Paul Ricoeur, e Walter Benjamin, desejamos compreender ...

  13. C-H and C-C activation of n -butane with zirconium hydrides supported on SBA15 containing N-donor ligands: [(≡SiNH-)(≡SiX-)ZrH2], [(≡SiNH-)(≡SiX-)2ZrH], and[(≡SiN=)(≡SiX-)ZrH] (X = -NH-, -O-). A DFT study

    KAUST Repository

    Pasha, Farhan Ahmad; Bendjeriou-Sedjerari, Anissa; Huang, Kuo-Wei; Basset, Jean-Marie

    2014-01-01

    : [(≡SiNH-)(≡SiO-)ZrH2] (A), [(≡SiNH-)2ZrH2] (B), [(≡SiNH-)(≡SiO-) 2ZrH] (C), [(≡SiNH-)2(≡SiO-)ZrH] (D), [(≡SiN=)(≡Si-O-)ZrH] (E), and [(≡SiN=)(≡SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C-H/C-C bond activation and cleavage

  14. Impact resistance of uncoated SiC/SiC composites

    International Nuclear Information System (INIS)

    Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis S.; Lee, Kang N.

    2008-01-01

    Two-dimensional woven SiC/SiC composites fabricated by melt infiltration method were impact tested at room temperature and at 1316 deg. C in air using 1.59-mm diameter steel-ball projectiles at velocities ranging from 115 to 400 m/s. The extent of substrate damage with increasing projectile velocity was imaged and analyzed using optical and scanning electron microscopy, and non-destructive evaluation (NDE) methods such as pulsed thermography, and computed tomography. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. Results indicate that at 115 m/s projectile velocity, the composite showed no noticeable surface or internal damage and retained its as-fabricated mechanical properties. As the projectile velocity increased above this value, the internal damage increased and mechanical properties degraded. At velocities >300 m/s, the projectile penetrated through the composite, but the composite retained ∼50% of the ultimate tensile strength of the as-fabricated composite and exhibited non-brittle failure. Predominant internal damages are delamination of fiber plies, fiber fracture and matrix shearing

  15. Effect of germanium concentrations on tunnelling current calculation of Si/Si1-xGex/Si heterojunction bipolar transistor

    Science.gov (United States)

    Hasanah, L.; Suhendi, E.; Khairrurijal

    2018-05-01

    Tunelling current calculation on Si/Si1-xGex/Si heterojunction bipolar transistor was carried out by including the coupling between transversal and longitudinal components of electron motion. The calculation results indicated that the coupling between kinetic energy in parallel and perpendicular to S1-xGex barrier surface affected tunneling current significantly when electron velocity was faster than 1x105 m/s. This analytical tunneling current model was then used to study how the germanium concentration in base to Si/Si1-xGex/Si heterojunction bipolar transistor influenced the tunneling current. It is obtained that tunneling current increased as the germanium concentration given in base decreased.

  16. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiN{sub x}/SiN{sub y} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiaofan; Ma, Zhongyuan, E-mail: zyma@nju.edu.cn; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan [National Laboratory of Solid State Microstructures, Jiangsu Provincial Key Laboratory of Photonic Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2014-09-28

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN{sub x}/SiN{sub y} multilayers with high on/off ratio of 10{sup 9}. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  17. Influence of substrate treatment on the growth of advanced core–shell alloys and compounds of FeSi@SiO2 and SiO2 nanowires

    CSIR Research Space (South Africa)

    Thabethe, S

    2014-12-01

    Full Text Available Advanced core–shell FeSi@SiO(subx) nanowires are observed when FeCl(sub3) vapour is made to flow over a SiO(sub2)/Si substrate at 1100 degress C. The thickness of the SiO(subx) sheath (d0) is found to depend inversely as the period of time of HF...

  18. Effects of C+ ion implantation on electrical properties of NiSiGe/SiGe contacts

    International Nuclear Information System (INIS)

    Zhang, B.; Yu, W.; Zhao, Q.T.; Buca, D.; Breuer, U.; Hartmann, J.-M.; Holländer, B.; Mantl, S.; Zhang, M.; Wang, X.

    2013-01-01

    We have investigated the morphology and electrical properties of NiSiGe/SiGe contact by C + ions pre-implanted into relaxed Si 0.8 Ge 0.2 layers. Cross-section transmission electron microscopy revealed that both the surface and interface of NiSiGe were improved by C + ions implantation. In addition, the effective hole Schottky barrier heights (Φ Bp ) of NiSiGe/SiGe were extracted. Φ Bp was observed to decrease substantially with an increase in C + ion implantation dose

  19. Si K-edge XANES study of SiOxCyHz amorphous polymeric materials

    International Nuclear Information System (INIS)

    Chaboy, J.; Barranco, A.; Yanguas-Gil, A.; Yubero, F.; Gonzalez-Elipe, A. R.

    2007-01-01

    This work reports on x-ray absorption spectroscopy study at the Si K edge of several amorphous SiO x C y H z polymers prepared by plasma-enhanced chemical-vapor deposition with different C/O ratios. SiO 2 and SiC have been used as reference materials. The comparison of the experimental Si K-edge x-ray absorption near-edge structure spectra with theoretical computations based on multiple scattering theory has allowed us to monitor the modification of the local coordination around Si as a function of the overall C/O ratio in this kind of materials

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

    Directory of Open Access Journals (Sweden)

    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.

  1. An optically controlled SiC lateral power transistor based on SiC/SiCGe super junction structure

    International Nuclear Information System (INIS)

    Pu Hongbin; Cao Lin; Ren Jie; Chen Zhiming; Nan Yagong

    2010-01-01

    An optically controlled SiC/SiCGe lateral power transistor based on superjunction structure has been proposed, in which n-SiCGe/p-SiC superjunction structure is employed to improve device figure of merit. Performance of the novel optically controlled power transistor was simulated using Silvaco Atlas tools, which has shown that the device has a very good response to the visible light and the near infrared light. The optoelectronic responsivities of the device at 0.5 μm and 0.7 μm are 330 mA/W and 76.2 mA/W at 2 V based voltage, respectively. (semiconductor devices)

  2. An optically controlled SiC lateral power transistor based on SiC/SiCGe super junction structure

    Energy Technology Data Exchange (ETDEWEB)

    Pu Hongbin; Cao Lin; Ren Jie; Chen Zhiming; Nan Yagong, E-mail: puhongbin@xaut.edu.c [Xi' an University of Technology, Xi' an 710048 (China)

    2010-04-15

    An optically controlled SiC/SiCGe lateral power transistor based on superjunction structure has been proposed, in which n-SiCGe/p-SiC superjunction structure is employed to improve device figure of merit. Performance of the novel optically controlled power transistor was simulated using Silvaco Atlas tools, which has shown that the device has a very good response to the visible light and the near infrared light. The optoelectronic responsivities of the device at 0.5 {mu}m and 0.7 {mu}m are 330 mA/W and 76.2 mA/W at 2 V based voltage, respectively. (semiconductor devices)

  3. Interfacial microstructure of NiSi x/HfO2/SiO x/Si gate stacks

    International Nuclear Information System (INIS)

    Gribelyuk, M.A.; Cabral, C.; Gusev, E.P.; Narayanan, V.

    2007-01-01

    Integration of NiSi x based fully silicided metal gates with HfO 2 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/HfO x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi x /HfO 2 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/HfO 2 , likely due to compositional non-uniformity of NiSi x . No intermixing between Hf, Ni and Si beyond interfacial roughness was observed

  4. Effect of PECVD SiNx/SiOy Nx –Si interface property on surface passivation of silicon wafer

    International Nuclear Information System (INIS)

    Jia Xiao-Jie; Zhou Chun-Lan; Zhou Su; Wang Wen-Jing; Zhu Jun-Jie

    2016-01-01

    It is studied in this paper that the electrical characteristics of the interface between SiO y N x /SiN x stack and silicon wafer affect silicon surface passivation. The effects of precursor flow ratio and deposition temperature of the SiO y N x layer on interface parameters, such as interface state density Di t and fixed charge Q f , and the surface passivation quality of silicon are observed. Capacitance–voltage measurements reveal that inserting a thin SiO y N x layer between the SiN x and the silicon wafer can suppress Q f in the film and D it at the interface. The positive Q f and D it and a high surface recombination velocity in stacks are observed to increase with the introduced oxygen and minimal hydrogen in the SiO y N x film increasing. Prepared by deposition at a low temperature and a low ratio of N 2 O/SiH 4 flow rate, the SiO y N x /SiN x stacks result in a low effective surface recombination velocity (S eff ) of 6 cm/s on a p-type 1 Ω·cm–5 Ω·cm FZ silicon wafer. The positive relationship between S eff and D it suggests that the saturation of the interface defect is the main passivation mechanism although the field-effect passivation provided by the fixed charges also make a contribution to it. (paper)

  5. Magnetron-sputter epitaxy of β-FeSi2(220)/Si(111) and β-FeSi2(431)/Si(001) thin films at elevated temperatures

    International Nuclear Information System (INIS)

    Liu Hongfei; Tan Chengcheh; Chi Dongzhi

    2012-01-01

    β-FeSi 2 thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 °C. On Si(111), the growth is consistent with the commonly observed orientation of [001]β-FeSi 2 (220)//[1-10]Si(111) having three variants, in-plane rotated 120° with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]β-FeSi 2 (431)//[110]Si(001) with four variants, which is hitherto unknown for growing β-FeSi 2 . Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between β-FeSi 2 grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of β-FeSi 2 /Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of β-FeSi 2 (431)/Si(001) is larger than that on the surface of β-FeSi 2 (220)/Si(111).

  6. Matrix densification of SiC composites by sintering process

    International Nuclear Information System (INIS)

    Kim, Young-Wook; Jang, Doo-Hee; Eom, Jung-Hye; Chun, Yong-Seong

    2007-02-01

    The objectives of this research are to develop a process for dense SiC fiber-SiC composites with a porosity of 5% or less and to develop high-strength SiC fiber-SiC composites with a strength of 500 MPa or higher. To meet the above objectives, the following research topics were investigated ; new process development for the densification of SiC fiber-SiC composites, effect of processing parameters on densification of SiC fiber-SiC composites, effect of additive composition on matrix microstructure, effects of additive composition and content on densification of SiC fiber-SiC composites, mechanical properties of SiC fiber-SiC composites, effect of fiber coating on densification and strength of SiC fiber-SiC composites, development of new additive composition. There has been a great deal of progress in the development of technologies for the processing and densification of SiC fiber-SiC composites and in better understanding of additive-densification-mechanical property relations as results of this project. Based on the progress, dense SiC fiber-SiC composites (≥97%) and high strength SiC fiber-SiC composites (≥600 MPa) have been developed. Development of 2D SiC fiber-SiC composites with a relative density of ≥97% and a strength of ≥600 MPa can be counted as a notable achievement

  7. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001).

    Science.gov (United States)

    Li, Lianbi; Zang, Yuan; Hu, Jichao; Lin, Shenghuang; Chen, Zhiming

    2017-05-25

    The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL) on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001) Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm², the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm². Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  8. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001

    Directory of Open Access Journals (Sweden)

    Lianbi Li

    2017-05-01

    Full Text Available The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001 Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 <21-1> at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm2, the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm2. Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  9. Electrical resistivity and thermal conductivity of SiC/Si ecoceramics prepared from sapele wood biocarbon

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; Gutierrez-Pardo, A.; Ramirez-Rico, J.

    2012-10-01

    Samples of β-SiC/Si ecoceramics with a silicon concentration of ˜21 vol % have been prepared using a series of consecutive procedures (carbonization of sapele wood biocarbon, synthesis of high-porosity biocarbon with channel-type pores, infiltration of molten silicon into empty channels of the biocarbon, formation of β-SiC, and retention of residual silicon in channels of β-SiC). The electrical resistivity ρ and thermal conductivity κ of the β-SiC/Si ecoceramic samples have been measured in the temperature range 5-300 K. The values of ρ{Si/chan}( T) and κ{Si/chan}( T) have been determined for silicon Sichan located in β-SiC channels of the synthesized β-SiC/Si ecoceramics. Based on the performed analysis of the obtained results, the concentration of charge carriers (holes) in Sichan has been estimated as p ˜ 1019 cm-3. The factors that can be responsible for such a high value of p have been discussed. The prospects for practical application of β-SiC/Si ecoceramics have been considered.

  10. Polarized luminescence of nc-Si-SiO x nanostructures on silicon substrates with patterned surface

    Science.gov (United States)

    Michailovska, Katerina; Mynko, Viktor; Indutnyi, Ivan; Shepeliavyi, Petro

    2018-05-01

    Polarization characteristics and spectra of photoluminescence (PL) of nc-Si-SiO x structures formed on the patterned and plane c-Si substrates are studied. The interference lithography with vacuum chalcogenide photoresist and anisotropic wet etching are used to form a periodic relief (diffraction grating) on the surface of the substrates. The studied nc-Si-SiO x structures were produced by oblique-angle deposition of Si monoxide in vacuum and the subsequent high-temperature annealing. The linear polarization memory (PM) effect in PL of studied structure on plane substrate is manifested only after the treatment of the structures in HF and is explained by the presence of elongated Si nanoparticles in the SiO x nanocolumns. But the PL output from the nc-Si-SiO x structure on the patterned substrate depends on how this radiation is polarized with respect to the grating grooves and is much less dependent on the polarization of the exciting light. The measured reflection spectra of nc-Si-SiO x structure on the patterned c-Si substrate confirmed the influence of pattern on the extraction of polarized PL.

  11. Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process

    Science.gov (United States)

    Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

    2017-11-01

    The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

  12. Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process.

    Science.gov (United States)

    Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

    2017-11-25

    The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

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

    Directory of Open Access Journals (Sweden)

    Lisandro Alejo Martinez

    2015-06-01

    Full Text Available 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 responder a dichos interrogantes, se propone llevar a cabo una lectura doble: leer a Habermas con Althusser y a Althusser con Habermas. En principio, se trata de leer a Habermas desde Althusser, con el propósito de analizar las implicancias procedentes de su crítica de las ideologías a través de un criterio normativo, cuyo punto de llegada es la comunidad de comunicación libre de dominio. Luego, en un segundo momento, se lleva a cabo una lectura de Althusser desde Habermas, con el objetivo de formularle a Althusser los interrogantes habermasianos sobre la función ideológica de la ciencia en el capitalismo tardío.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. RELAÇÃO ENTRE ENFERMEIROS E MÉDICOS NO HOSPITAL DAS CLÍNICAS DA UNIVERSIDADE FEDERAL DE GOIÁS: A PERSPECTIVA DO PROFISSIONAL DE ENFERMAGEM

    OpenAIRE

    ANA MARIA DE OLIVEIRA; ANDRÉ MOREIRA LEMES; BRUNA TEIXEIRA ÁVILA; CAROLINA ROCHA MACHADO; ELISA ORDONES; FERNANDA SOUZA MIRANDA; FERNANDA LOYOLA E SILVA; HERMANN SOARES GOETZ; JOSÉ OSCAR FERREIRA DE MIRANDA; JULIANE MOREIRA BARBOSA; LAHIS RIBEIRO LEÃO

    2010-01-01

    El conflicto en la relación entre médicos y enfermeras es un tema tabú en los servicios de salud y poco discutido en la literatura. Se sabe que el conflicto entre estas dos profesiones, identificados como los principales responsables de la atención al paciente, se debe a la combinación de diversos factores que van desde la creación del equipo multidisciplinario hasta las cuestiones salariales. El estudio tiene por objeto determinar si desde el punto de vista de enfermeria, hay un conflicto en...

  17. Disociación entre atribución de discapacidad explícita e implícita hacia adultos mayores en estudiantes de psicología

    OpenAIRE

    Serrani Azcurra, Daniel Jorge Luis

    2010-01-01

    Los adultos mayores son objeto de estereotipos negativos que pueden explorarse por medidas explícitas e implícitas. Dado que existen discrepancias entre ambas, es conveniente combinarlas. Son escasos los estudios sobre atribución de discapacidad hacia adultos mayores por parte de jóvenes en el ámbito educativo. El objetivo del estudio que se informa fue evaluar si existe una disociación entre las medidas implícitas y explícitas de atribución de discapacidad hacia adultos mayores en una cohort...

  18. De l’amour et du mariage. Une correspondance familiale au xixe siècle

    OpenAIRE

    Dauphin, Cécile; Poublan, Danièle

    2013-01-01

    L’article se propose d’explorer ce qui est dit du mariage et de l’amour dans la correspondance d’une famille bourgeoise qui couvre plusieurs générations sur un large xixe siècle. Trois épisodes ont été retenus qui permettent d’observer bien des tensions entre mariage arrangé et mariage d’inclination. D’abord, au début du siècle, la correspondance d’un jeune homme à l’aube d’une brillante carrière scientifique explicite les « raisons » sociales et économiques qui déterminent son choix matrimon...

  19. siRNA and innate immunity.

    Science.gov (United States)

    Robbins, Marjorie; Judge, Adam; MacLachlan, Ian

    2009-06-01

    Canonical small interfering RNA (siRNA) duplexes are potent activators of the mammalian innate immune system. The induction of innate immunity by siRNA is dependent on siRNA structure and sequence, method of delivery, and cell type. Synthetic siRNA in delivery vehicles that facilitate cellular uptake can induce high levels of inflammatory cytokines and interferons after systemic administration in mammals and in primary human blood cell cultures. This activation is predominantly mediated by immune cells, normally via a Toll-like receptor (TLR) pathway. The siRNA sequence dependency of these pathways varies with the type and location of the TLR involved. Alternatively nonimmune cell activation may also occur, typically resulting from siRNA interaction with cytoplasmic RNA sensors such as RIG1. As immune activation by siRNA-based drugs represents an undesirable side effect due to the considerable toxicities associated with excessive cytokine release in humans, understanding and abrogating this activity will be a critical component in the development of safe and effective therapeutics. This review describes the intracellular mechanisms of innate immune activation by siRNA, the design of appropriate sequences and chemical modification approaches, and suitable experimental methods for studying their effects, with a view toward reducing siRNA-mediated off-target effects.

  20. SiD Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. SOBRE LA TENSIÓN ENTRE ONTOLOGÍA E HISTORIA: EL SER DE LO POLÍTICO COMO DIFERENCIA

    Directory of Open Access Journals (Sweden)

    Nuria Yabkowski

    2010-12-01

    Full Text Available Resumen Proponer una ontología de lo político implica preguntarse por la relación que se establece entre ontología e historia. Si ambos términos se presentan como opuestos y excluyentes entre sí, entonces tendríamos que aceptar la posibilidad de que lo político pueda concebirse con plena autonomía de un contexto histórico determinado. Aquí, por el contrario, se trata de pensar una ontología de lo político que mantenga con la historia una relación distinta o, en otras palabras, una ontología política materialista. Para abordar esta problemática partimos de la obra de Nicos Poulantzas, para dar cuenta con ella de las dificultades que enfrentaba un marxismo en crisis a la hora de pensar la autonomía de la política. El posmarxismo enfrenta estos dilemas y elabora algunas respuestas sobre la relación entre ontología e historia. Para exponer lo que muchos de estos desarrollos comparten, recurrimos a la interpretación de Oliver Marchart sobre lo que él denomina el pensamiento político posfundacional (Cf. Lefort, Badiou, Laclau, Rancière. Luego recurrimos a los postulados de Gilles Deleuze, porque con ellos podemos desplazar de otra forma la tradicional antinomia entre ontología e historia. Entonces, asumiendo que el Ser de lo político es un ser que siempre se dice de la diferencia, nos abocamos a analizar críticamente las teorizaciones de Ernesto Laclau sobre la política y su forma hegemónica. Finalmente, la relación que propone Benjamín Arditi entre espectro y populismo permite pensar nuevas relaciones entre la ontología y la historia, lo político y la diferencia, dinamizando los conceptos.

  3. Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    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 O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} 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.

  4. Characterization of SiC–SiC composites for accident tolerant fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Deck, C.P., E-mail: Christian.Deck@ga.com; Jacobsen, G.M.; Sheeder, J.; Gutierrez, O.; Zhang, J.; Stone, J.; Khalifa, H.E.; Back, C.A.

    2015-11-15

    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.

  5. Mechanism of Si intercalation in defective graphene on SiC

    KAUST Repository

    Kaloni, Thaneshwor P.; Cheng, Yingchun; Schwingenschlö gl, Udo; Upadhyay Kahaly, M.

    2012-01-01

    Previously reported experimental findings on Si-intercalated graphene on SiC(0001) seem to indicate the possibility of an intercalation process based on the migration of the intercalant through atomic defects in the graphene sheet. We employ density

  6. Formation mechanism of SiC in C-Si system by ion irradiation

    International Nuclear Information System (INIS)

    Hishita, Shunichi; Aizawa, Takashi; Suehara, Shigeru; Haneda, Hajime

    2003-01-01

    The irradiation effects of 2 MeV He + , Ne + , and Ar + ions on the film structure of the C-Si system were investigated with RHEED and XPS. The ion dose dependence of the SiC formation was kinetically analyzed. The SiC formation at moderate temperature was achieved by 2 MeV ion irradiation when the thickness of the initial carbon films was appropriate. The evolution process of the SiC film thickness consisted of the 3 stages. The first stage was the steep increase of the SiC, and was governed by the inelastic collision. The second was the gentle increase of the SiC, and was governed by the diffusion. The last was the decrease of the SiC, and was caused by the sputtering. The formation mechanism of the SiC was discussed. (author)

  7. Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111/Si(111

    Directory of Open Access Journals (Sweden)

    Abe Shunsuke

    2010-01-01

    Full Text Available Abstract Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111 thin films on Si(111 has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D2-TPD and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111/Si(111 is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001 proceeds.

  8. Dielectric Properties of SiCf/PyC/SiC Composites After Oxidation

    Institute of Scientific and Technical Information of China (English)

    SONG Huihui; ZHOU Wancheng; LUO Fa; QING Yuchang; CHEN Malin; LI Zhimin

    2016-01-01

    In this paper, the SiC fiber-reinforced SiC matrix composites with a 0.15mm thick pyrocarbon interphase (notedas SiCf/PyC/SiC) were prepared by chemical vapor infiltration (CVI). The SiCf/PyC/SiC were oxidized in air at 950℃ for 50h. The dielectric properties after this high temperature oxidation were investigated in X-band from room temperature (RT) to 700℃. Results suggested that:e' of the SiCf/PyC/SiC after oxidation increased at first then de-creased with temperature elevating;e" increased with temperature raising in the temperature range studied.

  9. Fermi surfaces of YRu2Si2 and LaRu2Si2

    International Nuclear Information System (INIS)

    Settai, R.; Ikezawa, H.; Toshima, H.; Takashita, M.; Ebihara, T.; Sugawara, H.; Kimura, T.; Motoki, K.; Onuki, Y.

    1995-01-01

    We have measured the de Haas-van Alphen effect of YRu 2 Si 2 and LaRu 2 Si 2 to clarify the Fermi surfaces and cyclotron masses. Main hole-Fermi surfaces of both compounds with a distorted ellipsoid shape are similar, occupying about half of the Brillouin zone. The small hole-Fermi surfaces with the shape of a rugby ball are three in number for LaRu 2 Si 2 , and one for YRu 2 Si 2 . An electron-Fermi surface consists of a doughnut like shape for LaRu 2 Si 2 , while a cylinder along the [001] direction and a multiply-connected shape exist for YRu 2 Si 2 . The cyclotron masses of YRu 2 Si 2 are a little larger than those of LaRu 2 Si 2 . ((orig.))

  10. A sensitive optical sensor based on DNA-labelled Si@SiO2 core ...

    Indian Academy of Sciences (India)

    2017-10-31

    Oct 31, 2017 ... Si@SiO2 core–shell nanoparticles were proposed for the development of fluorescent mercury ... orophores, due to their unique optical properties, such as .... were made by evaporating one drop of the sample solution on.

  11. Ni-Si oxide as an inducing crystallization source for making poly-Si

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Zhiguo; Liu, Zhaojun; Li, Juan; Wu, Chunya; Xiong, Shaozhen [Institute of Photo-electronics, Nankai University, Tianjin (China); Zhao, Shuyun; Wong, Man; Kwok, Hoi Sing [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong (China)

    2010-04-15

    Nickel silicon oxide mixture was sputtered on a-Si with Ni-Si alloy target with Ni:Si weight ratio of 1:9 and used as a new inducing source for metal induced lateral crystallization (MILC). The characteristics of the resulted poly-Si materials induced by Ni-Si oxide with different thickness were nearly the same. This means the metal induced crystallization with this new inducing source has wide processing tolerance to make MILC poly-Si. Besides, it reduced the residual Ni content in the resulted poly-Si film. The transfer characteristic curve of poly-Si TFT and a TFT-OLED display demo made with this kind of new inducing source were also presented in this paper. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Rod-like β-FeSi2 phase grown on Si (111) substrate

    International Nuclear Information System (INIS)

    Han Ming; Tanaka, Miyoko; Takeguchi, Masaki; Furuya, Kazuo

    2004-01-01

    Pure Fe with coverage of 0.5-2.0 nm was deposited on Si (111) 7x7 surfaces by reactive deposition epitaxy (RDE) in an integrated ultrahigh vacuum (UHV) system. Transmission electron microscopy (TEM) confirmed that the as-deposited epitaxial phase exhibits rod-like and equilateral triangular morphology. The as-deposited phase was identified as c-FeSi 2 by electron diffraction and high-resolution transmission electron microscopy. It was found that there exists lattice distortion in epitaxial c-FeSi 2 phase. Upon annealing at 1073 K, the metastable c-FeSi 2 transforms into equilibrium β-FeSi 2 phase, the latter inherits completely the morphology of c-FeSi 2 phase. Based on RDE and subsequent annealing, a new fabrication technique to grow rod-like semiconducting β-FeSi 2 on a Si substrate has been proposed in the present work

  13. Development of SiC/SiC composite for fusion application

    International Nuclear Information System (INIS)

    Kohyama, A.; Katoh, Y.; Snead, L.L.; Jones, R.H.

    2001-01-01

    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)

  14. Divergencias en la conceptualización de la relación entre culturas

    Directory of Open Access Journals (Sweden)

    César Cisternas Irarrázabal

    Full Text Available Resumen La conceptualización de la relación entre culturas es un tópico que está lejos de un acuerdo sobre cuál es el mejor término para analizar aquella realidad. Desde diferentes corrientes filosóficas, tales como el liberalismo, republicanismo, comunitarismo o postcolonialismo, se han dado miríadas de visiones sobre la materia, en las cuales también ha jugado un papel el uso pragmático que se le da a los conceptos. El presente artículo pretende mapear la discusión en este campo. Para esto, se dividió el debate geopolíticamente; de este modo, se presenta, por una parte, la realidad en la modernidad central, y por la otra, el estado del arte en Latinoamérica. Se llega a la conclusión que, en muchos casos, las diferencias entre los enfoques no son tan radicales como pareciera a primera vista en la discusión. Asimismo, se observa que existen ciertos puntos sobre los cuales cualquier sugerencia en materia de interculturalidad debe pronunciarse, a saber, la naturaleza de las identidades, las características deseadas del Estado-nación, la postura frente a la modernidad occidental, la aceptabilidad de la democracia y los derechos humanos como valores universales, quiénes son los sujetos interculturales y si las relaciones se deben basar en la igualdad o el reconocimiento. 1

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Effect of irradiation on thermal expansion of SiCf/SiC composites

    International Nuclear Information System (INIS)

    Senor, D.J.; Trimble, D.J.; Woods, J.J.

    1996-06-01

    Linear thermal expansion was measured on five different SiC-fiber-reinforced/SiC-matrix (SiC f /SiC) composite types in the unirradiated and irradiated conditions. Two matrices were studied in combination with Nicalon CG reinforcement and a 150 nm PyC fiber/matrix interface: chemical vapor infiltrated (CVI) SiC and liquid-phase polymer impregnated precursor (PIP) SiC. Composites of PIP SiC with Tyranno and HPZ fiber reinforcement and a 150 nm PyC interface were also tested, as were PIP SiC composites with Nicalon CG reinforcement and a 150 nm BN fiber/matrix interface. The irradiation was conducted in the Experimental Breeder Reactor-II at a nominal temperature of 1,000 C to doses of either 33 or 43 dpa-SiC. Irradiation caused complete fiber/matrix debonding in the CVI SiC composites due to a dimensional stability mismatch between fiber and matrix, while the PIP SiC composites partially retained their fiber/matrix interface after irradiation. However, the thermal expansion of all the materials tested was found to be primarily dependent on the matrix and independent of either the fiber or the fiber/matrix interface. Further, irradiation had no significant effect on thermal expansion for either the CVI SiC or PIP SiC composites. In general, the thermal expansion of the CVI SiC composites exceeded that of the PIP SiC composites, particularly at elevated temperatures, but the expansion of both matrix types was less than chemical vapor deposited (CVD) β-SiC at all temperatures

  17. Hybrid Integrated Si/SiN Platforms for Wideband Optical Processing

    Science.gov (United States)

    2017-05-08

    annealing process, makes the process prone to dopant redistribution, that hinderers the SiN deposition after full Si device fabrication. To resolve...with 220 nm of crystalline Si. In parallel, a Si die goes through a wet oxidation process to grow 5 μm of thermal oxide. In the next step, 400 nm of... annealing methods. As a figure of merit in hydrophilic bonding, we monitored the surface roughness and bonding strength of a thin oxide layer to

  18. Formation of ferromagnetic interface between β-FeSi2 and Si(111) substrate

    International Nuclear Information System (INIS)

    Hattori, Azusa N.; Hattori, Ken; Kodama, Kenji; Hosoito, Nobuyoshi; Daimon, Hiroshi

    2007-01-01

    Epitaxial β-FeSi 2 thin films were grown on Si(111)7x7 clean surfaces by solid phase epitaxy in ultrahigh vacuum: iron deposition at low temperature and subsequent annealing. We found that a ferromagnetic interface layer of iron-rich silicides forms between a β-FeSi 2 surface layer and a Si(111) substrate spontaneously from transmission electron microscopy observations and magnetization measurements

  19. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    International Nuclear Information System (INIS)

    Youngblood, G.E.; Jones, R.H.

    1998-01-01

    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 x 6 x 2 mm 3 with a span-to-depth ratio of 10/1

  20. Passivation of surface-nanostructured f-SiC and porous SiC

    DEFF Research Database (Denmark)

    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....

  1. A FOTOGRAFIA ENTRE A ARTE POPULAR E A ARTE ERUDITA

    Directory of Open Access Journals (Sweden)

    Marcos Fabris

    2013-09-01

    Full Text Available Este artigo pretende discutir alguns dos aspectos que marcam o estabelecimento e a dissolução das fronteiras entre dois pólos convencionalmente descritos como arte culta e arte popular, tecendo paralelos entre o teatro de variedades, forma de expressão popular por excelência, e a fotografia, expressão artística que desde seus primórdios circula entre os dois extremos deste contínuo. Nestes termos, ambiciona-se verificar como determinadas condições sócio-históricas favorecem a criação de recursos formais que minimizam, ou suprimem, tais distinções consagradas pela crítica de arte.

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

    Directory of Open Access Journals (Sweden)

    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

  3. Relaciones cuantitativas entre los contenidos de azufre y de sulfuros en los aceros inoxidables tipo AISI 303: influencia de la composición química de los sulfuros

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1999-06-01

    Full Text Available The work has been done with ten AISI 303 stainless steel rods which have similar chemical compositions, except for sulphur which varies between 0.25 and 0.36%. These steels are studied by Scanning Electron Microscopy (SEM and Energy Dispersive X-Ray Spectrometry (EDX. The sulphides are chemically microanalysed and the occupied volume determined by automatic image analysis. It can be inferred that the chemical composition of sulphides in AISI 303 steels is variable to some extent even though the steel chemistry is almost invariable. This could mean that solidification conditions and thermomechanical transformations are able to affect resulting in variations of sulphide compositions. Quantitative relations between sulphur and sulphide contents are established and the influence of sulphide chemical compositions on those relations is studied. The experimental results are compared with those obtained from theoretical calculations. A good approach is obtained when the difference between chemical compositions of real sulphides and the theoretical one, MnS, is taken into account.

    Se trabaja con una serie de diez redondos de aceros inoxidables tipo AISI 303 de composiciones químicas prácticamente iguales a excepción del azufre que varía entre 0,25 y 0,36%. Se examinan los aceros mediante Microscopía Electrónica de Barrido (MEB y Espectrometría de Dispersión de Energías de Rayos X (EDX acoplada al MEB, analizándose químicamente los sulfuros y determinando, mediante análisis automático de imágenes, los volúmenes ocupados por los sulfuros. Parece deducible que la composición química de los sulfuros en el AISI 303 puede ser discretamente variable aún siendo prácticamente invariable la composición química del acero. Ello podría significar que las condiciones de solidificación y las transformaciones termomecánicas pueden influir, dando como resultado variaciones en la composición química de los sulfuros. Se establecen

  4. Determinantes de la precarización laboral en Argentina entre 2003-2013: entre los cambios y las continuidades

    Directory of Open Access Journals (Sweden)

    Marcelo Delfini

    2016-03-01

    Full Text Available El crecimiento económico experimentado por Argentina desde 2003 ha tenido su correlato en la mejora de los indicadores laborales. No obstante, la precarización laboral se ha mantenido, luego de una baja importante hasta el año 2007, en valores muy elevados. Partiendo de la idea central que la precarización constituye para el capital, una reducción de costos, el objetivo de este artículo es dar cuenta de los determinantes de la informalidad entre los trabajadores asalariados, estableciendo continuidades y cambios entre los años 2003 y 2013. Para ello utilizamos una metodología cuantitativa con fuentes secundarias de información, a partir de las cuales realizamos dos tipo de análisis, el primero de carácter descriptivo a partir del cual se busca dar cuenta de las características del mercado de trabajo argentino entre 1990 y 2013 y el segundo se realiza por medio de una regresión logística binomial, que permite acercarnos a los determinantes de la precarización de las condiciones de trabajo. En este sentido, se pudo observar que entre los años 2003 y 2013, se consolidó una precarización laboral, cuyos determinantes no lograron modificarse sustancialmente entre los años de referencia.

  5. La enseñanza de la salud pública en la formación de grado : Estudio comparativo entre las carreras de Medicina de la UNLP, la UNR y la UNC

    OpenAIRE

    Alconada Magliano, Juan P.

    2013-01-01

    Objetivo general Evaluar, a través de un estudio comparativo entre tres universidades públicas argentinas (La Plata, Córdoba y Rosario), si la propuesta de enseñanza de la salud pública en la formación de Grado, permite la formación de un médico acorde a las necesidades de la comunidad. Objetivos específicos Evaluar si la propuesta de enseñanza capacita al futuro médico para: - Identificar grupos de riesgo en una comunidad determinada. - Ide...

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

    NARCIS (Netherlands)

    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

  7. Thermal Stability of siRNA Modulates Aptamer- conjugated siRNA Inhibition

    Directory of Open Access Journals (Sweden)

    Alexey Berezhnoy

    2012-01-01

    Full Text Available Oligonucleotide aptamer-mediated in vivo cell targeting of small interfering RNAs (siRNAs is emerging as a useful approach to enhance the efficacy and reduce the adverse effects resulting from siRNA-mediated genetic interference. A current main impediment in aptamer-mediated siRNA targeting is that the activity of the siRNA is often compromised when conjugated to an aptamer, often requiring labor intensive and time consuming design and testing of multiple configurations to identify a conjugate in which the siRNA activity has not been significantly reduced. Here, we show that the thermal stability of the siRNA is an important parameter of siRNA activity in its conjugated form, and that siRNAs with lower melting temperature (Tm are not or are minimally affected when conjugated to the 3′ end of 2′F-pyrimidine-modified aptamers. In addition, the configuration of the aptamer-siRNA conjugate retains activity comparable with the free siRNA duplex when the passenger strand is co-transcribed with the aptamer and 3′ overhangs on the passenger strand are removed. The approach described in this paper significantly reduces the time and effort necessary to screening siRNA sequences that retain biological activity upon aptamer conjugation, facilitating the process of identifying candidate aptamer-siRNA conjugates suitable for in vivo testing.

  8. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Science.gov (United States)

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-28

    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.

  9. Tunable Synthesis of SiC/SiO2 Heterojunctions via Temperature Modulation

    Directory of Open Access Journals (Sweden)

    Wei Li

    2018-05-01

    Full Text Available A large-scale production of necklace-like SiC/SiO2 heterojunctions was obtained by a molten salt-mediated chemical vapor reaction technique without a metallic catalyst or flowing gas. The effect of the firing temperature on the evolution of the phase composition, microstructure, and morphology of the SiC/SiO2 heterojunctions was studied. The necklace-like SiC/SiO2 nanochains, several centimeters in length, were composed of SiC/SiO2 core-shell chains and amorphous SiO2 beans. The morphologies of the as-prepared products could be tuned by adjusting the firing temperature. In fact, the diameter of the SiO2 beans decreased, whereas the diameter of the SiC fibers and the thickness of the SiO2 shell increased as the temperature increased. The growth mechanism of the necklace-like structure was controlled by the vapor-solid growth procedure and the modulation procedure via a molten salt-mediated chemical vapor reaction process.

  10. Status and prospects for SiC-SiC composite materials development for fusion applications

    International Nuclear Information System (INIS)

    Sharafat, S.; Jones, R.H.; Kohyama, A.; Fenici, P.

    1995-01-01

    Silicon carbide (SiC) composites are very attractive for fusion applications because of their low afterheat and low activation characteristics coupled with excellent high temperature properties. These composites are relatively new materials that will require material development as well as evaluation of hermiticity, thermal conductivity, radiation stability, high temperature strength, fatigue, thermal shock, and joining techniques. The radiation stability of SiC-SiC composites is a critical aspect of their application as fusion components and recent results will be reported. Many of the non-fusion specific issues are under evaluation by other ceramic composite development programs, such as the US national continuous fiber ceramic composites.The current development status of various SiC-SiC composites research and development efforts is given. Effect of neutron irradiation on the properties of SiC-SiC composite between 500 and 1200 C are reported. Novel high temperature properties specific to ceramic matrix composite (CMC) materials are discussed. The chemical stability of SiC is reviewed briefly. Ongoing research and development efforts for joining CMC materials including SiC-SiC composites are described. In conclusion, ongoing research and development efforts show extremely promising properties and behavior for SiC-SiC composites for fusion applications. (orig.)

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

    Directory of Open Access Journals (Sweden)

    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

  12. Thermochemical instability effects in SiC-based fibers and SiC{sub f}/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  14. Relaciones entre los salarios y la productividad en Colombia

    OpenAIRE

    Méndez Sayago, Jhon Alexander

    2017-01-01

    Esta tesis de doctorado está compuesta de cuatro artículos que tienen como propósito estudiar las relaciones entre los salarios y la productividad laboral en Colombia. Los dos primeros artículos denominados “Salario real y eficiencia del trabajo en el sector manufacturero en Colombia” y “Análisis de causalidad y sensibilidad entre los salarios reales y la productividad laboral en el sector manufacturero a partir de cifras de los departamentos en Colombia” aportan evidencia empírica sobre la d...

  15. Arquitectura de comunicación entre frameworks jadesymfony

    OpenAIRE

    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...

  16. Entre ritmo e poesia: rap e literatura oral urbana

    Directory of Open Access Journals (Sweden)

    Marcus Rogerio Salgado

    2015-11-01

    Full Text Available O objetivo do presente artigo é um estudo do rap enquanto manifestação de literatura oral urbana e forma de oralidade tecnológica. Para tanto, o artigo passará em revista as relações entre literatura e palavra falada/cantada, assim como as possibilidades de interface estética entre a literatura e a música que estão em questão quando tratamos do rap.

  17. Factores de riesgo que condicionan la conducta machista entre adolescentes.

    OpenAIRE

    Sánchez Alonso, Isabel

    2016-01-01

    Este trabajo sobre los factores de riesgo que condicionan la violencia machista entre adolescentes, recoge las principales argumentaciones que explican el origen de la desigualdad entre hombres y mujeres y de cómo la diferencia biológica ha incidido en la división del trabajo según el sexo y en las funciones y roles que debe desempeñar cada uno. A continuación señala los principales factores de riesgo que condicionan la violencia machista en las primeras relaciones am...

  18. Encuentros improbables: Cervantes y Shakespeare entre Borges y Burgess

    OpenAIRE

    Martínez, Zenón Luis

    2016-01-01

    En sus biografías sobre Cervantes y Shakespeare, Luis Astrana Marín especuló con un encuentro entre ambos con ocasión de la ratificación en 1605 en Valladolid del Tratado de Londres. Este improbable encuentro ha seguido alimentando ficciones históricas y fantasías literarias. El cruce de caminos entre Cervantes y Shakespeare tiene lugar en torno a la perdida tragicomedia The History of Cardenio (1612?), atribuida a John Fletcher y William Shakespeare. La recon...

  19. Entre Madres: Talleres de Comunicación

    OpenAIRE

    Cardoso Moreno, María Jesús; Aragonés, Lucía Tomás

    2015-01-01

    En el presente artículo se expone el trabajo de investigación cuyo objetivo fue conocer el grado de satisfacción de las madres con un taller de formación denominado "Entremadres". Las 150 mujeres madres que participaron en el taller en la ciudad de Zaragoza, España, se conformaron en un grupo de 7 u 8 madres y estuvo compuesto por seis sesiones de dos horas cada una, entre los años 2008 y 2013. Este taller fue dirigido a madres con hijos de edades comprendidas entre 2 y 16 años. La frecuencia...

  20. Addimer diffusions on Si(100)

    International Nuclear Information System (INIS)

    Lee, Gun Do; Wang, C. Z.; Lu, Z. Y.; Ho, K. M.

    1999-01-01

    The diffusion pathways along the trough and between the trough and the dimer row on the Si(100) surface are investigated by tight-binding molecular dynamics calculations using the environment dependent tight-binding silicon potential and by ab initio calculations using the Car-Parrinello method. The studies discover new diffusion pathways consisting of rotation of addimer. The calculated energy barrier are in excellent agreement with experiment. The rotational diffusion pathway between the trough and the dimer row is much more energetically favorable than other diffusion pathways by parallel and perpendicular addimer. The new pathway along the trough is nearly same as the energy barrier of the diffusion pathway by dissociation of the addimer

  1. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  2. L’histoire entre la guerre des mémoires et la Justice

    Directory of Open Access Journals (Sweden)

    François Dosse

    2017-07-01

    Full Text Available La question se pose de savoir si la Justice est capable de réparer le tragique de l’histoire. François Dosse situe son analyse sur l’axe pragmatique de la préoccupation citoyenne exprimée par Ricœur, dès les premières lignes de La mémoire, l’histoire, l’oubli, lorsqu’il se dit troublé par le trop de mémoire ici et le trop d’oubli ailleurs. On assiste en effet à une judiciarisation progressive de la discipline historique. Elle se traduit par une inquiétante inflation mémorielle depuis la loi Gayssot de 1990. La fonction du juge et de l’historien a certes des points communs, comme l’a montré Marc Bloch dans Apologie pour l’histoire ou Carlo Ginzburg dans Le juge et l’historien. Le juge d’instruction peut s’apparenter à l’historien, mais pas celui du siège qui doit rendre un jugement. Cette emprise progressive de la justice sur le passé a pour effet pervers une tentative de sanctuarisation des questions historiques. Ricœur nous aide à repenser les relations entre justice, histoire et mémoire en distinguant et en articulant ces diverses dimensions par un travail de clarification des concepts. Il permet de mieux articuler la fonction judiciaire, le travail de mémoire et l’opération historiographique en respectant la validité de chacune de ces dimensions.

  3. Correlación entre actitud hacia homosexualidad femenina y masculina en estudiantes de Medicina/ Correlation between the attitude toward female and male homosexuality in medical

    Directory of Open Access Journals (Sweden)

    Adalberto Campo-Arias

    2017-04-01

    Full Text Available Este artículo es resultado de una investigación cuyo objetivo fue explorar la correlación cuantitativa entre homofobia y lesbofobia en estudiantes de medicina de una universidad de Bogotá, Colombia. El estudio transversal se llevó a cabo con estudiantes de medicina mayores de 18 años. La homofobia y la lesbofobia se midieron con la Escala para Actitud hacia Gais y Lesbianas (ATGL. La ATGL se compone de dos escalas de diez ítems: Escala para Actitud hacia Hombres Gais (ATG y la Escala para Actitud hacia Mujeres Lesbianas (ATL. La correlación entre puntuaciones para homofobia y lesbofobia se calculó con coeficiente de Pearson (r. Se planteó la hipótesis de que homofobia y lesbofobia eran diferentes construcciones si la correlación entre las escalas era inferior a 0,60. Un total de 359 estudiantes de medicina participaron en la investigación, la media para la edad fue de 20,2 años (DE=1,9, y el 59,1% eran mujeres. Las puntuaciones en la ATG (alfa de Cronbach de 0,85 se observaron entre 10 y 50, con una media de 27,9 (DE=8,1 y en la ATL (alfa de Cronbach de 0,73 entre 10 y 45, con media de 24,8 (DE=6,8. La correlación entre homofobia (ATG y lesbofobia (ATL fue r=0,64 (p<0,001. Se concluye que la ATG y ATL muestran correlación altamente significativa, lo que sugiere que homofobia y lesbofobia no son constructos completamente diferentes y podrían incluirse en el concepto general de prejuicio sexual. Otras investigaciones deben corroborar el presente hallazgo.

  4. Evidencia morfológica de hibridación entre las subespecies de Ramphocelus flammigerus (Passeriformes: Thraupidae en Colombia

    Directory of Open Access Journals (Sweden)

    M. Juliana Bedoya

    2012-03-01

    Full Text Available Las modificaciones de los hábitats naturales, tales como la deforestación y el incremento de las actividades agrícolas, han conducido a interacciones faunísticas inusuales. En Colombia, esta situación ha generado el contacto secundario entre las poblaciones de las subespecies de Ramphocelus flammigerus del Valle del Cauca y de la costa Pacífica; y se han encontrado individuos con rabadillas de colores intermedios entre las subespecies que se han catalogado como híbridos. El objetivo del presente estudio fue evaluar si existe evidencia morfológica que sugiera hibridación y que pueda explicar el origen de los individuos de coloración intermedia. Con este fin, se obtuvieron muestras de 15 localidades; 10 zonas alopátricas (cinco por cada subespecie y cinco zonas simpátricas. Para la captura de individuos se utilizaron redes de niebla y fueron tomados siete caracteres morfológicos. Asimismo, se predijo que si las subespecies están hibridando, las mismas, podrían ser morfológicamente más similares cuando coexisten que cuando se encuentran separadas. Alternativamente, cuando las subespecies coexisten, éstas pueden divergir en simpatría debido a presiones selectivas para reducir la competencia por recursos (desplazamiento de caracteres. Para identificar los patrones de variación morfológica, se comparó la morfología de las subespecies, de poblaciones simpátricas y alopátricas de ambas subespecies y de los individuos de cloración intermedia. Consecuentemente, se realizó un análisis discriminante y se evaluaron las diferencias entre los grupos con la utilización de intervalos de confianza del 95% para las relaciones logarítmicas. Y se capturaron un total de 112 individuos (46 de coloraciones intermedias, 20 R. f. flammigerus y 46 R. f. icteronotus. Los análisis discriminantes mostraron que las subespecies se diferencian entre ellas y que los individuos de coloraciones intermedias se traslapan con estas. Las relaciones logar

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

    Directory of Open Access Journals (Sweden)

    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

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

    Directory of Open Access Journals (Sweden)

    Javier Llorca Díaz

    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.

  7. Transformation of sludge Si to nano-Si/SiOx structure by oxygen inward diffusion as precursor for high performance anodes in lithium ion batteries

    Science.gov (United States)

    Hua, Qiqi; Dai, Dongyang; Zhang, Chengzhi; Han, Fei; Lv, Tiezheng; Li, Xiaoshan; Wang, Shijie; Zhu, Rui; Liao, Haojie; Zhang, Shiguo

    2018-05-01

    Although several Si/C composite structures have been proposed for high-performance lithium-ion batteries (LIBs), they have still suffered from expensive and complex processes of nano-Si production. Herein, a simple, controllable oxygen inward diffusion was utilized to transform Si sludge obtained from the photovoltaic (PV) industry into the nano-Si/SiOx structure as a result of the high diffusion efficiency of O inside Si and high surface area of the sludge. After further process, a yolk/shell Si/C structure was obtained as an anode material for LIBs. This composite demonstrated an excellent cycling stability, with a high reversible capacity (˜ 1250 mAh/g for 500 cycles), by void space originally left by the SiOx accommodate inner Si expansion. We believe this is a rather simple way to convert the waste Si into a valuable nano-Si for LIB applications.

  8. Formation of metallic Si and SiC nanoparticles from SiO2 particles by plasma-induced cathodic discharge electrolysis in chloride melt

    International Nuclear Information System (INIS)

    Tokushige, M.; Tsujimura, H.; Nishikiori, T.; Ito, Y.

    2013-01-01

    Silicon nanoparticles are formed from SiO 2 particles by conducting plasma-induced cathodic discharge electrolysis. In a LiCl–KCl melt in which SiO 2 particles were suspended at 450 °C, we obtained Si nanoparticles with diameters around 20 nm. During the electrolysis period, SiO 2 particles are directly reduced by discharge electrons on the surface of the melt just under the discharge, and the deposited Si atom clusters form Si nanoparticles, which leave the surface of the original SiO 2 particle due to free spaces caused by a molar volume difference between SiO 2 and Si. We also found that SiC nanoparticles can be obtained using carbon anode. Based on Faraday's law, the current efficiency for the formation of Si nanoparticles is 70%

  9. SI konkurss / Anna Roomet

    Index Scriptorium Estoniae

    Roomet, Anna

    2006-01-01

    Konkursist, auhinnatseremooniast ja ekspositsioonist Arhitektuuri- ja Disainigaleriis, žürii koosseis. Intervjuu eesti parima noore disaineri preemia SÄSI pälvinud Pavel Sidorenko ning väikese SÄSI saanud Björn Koobi, Ülle Jehe ja Igor Volkoviga

  10. Intranasal delivery of antiviral siRNA.

    Science.gov (United States)

    Barik, Sailen

    2011-01-01

    Intranasal administration of synthetic siRNA is an effective modality of RNAi delivery for the prevention and therapy of respiratory diseases, including pulmonary infections. Vehicles used for nasal siRNA delivery include established as well as novel reagents, many of which have been recently optimized. In general, they all promote significant uptake of siRNA into the lower respiratory tract, including the lung. When properly designed and optimized, these siRNAs offer significant protection against respiratory viruses such as influenza virus, parainfluenza virus and respiratory syncytial virus (RSV). Nasally administered siRNA remains within the lung and does not access systemic blood flow, as judged by its absence in other major organs such as liver, heart, kidney, and skeletal muscle. Adverse immune reaction is generally not encountered, especially when immunogenic and/or off-target siRNA sequences and toxic vehicles are avoided. In fact, siRNA against RSV has entered Phase II clinical trials in human with promising results. Here, we provide a standardized procedure for using the nose as a specific route for siRNA delivery into the lung of laboratory animals. It should be clear that this simple and efficient system has enormous potential for therapeutics.

  11. Self-aligned indium–gallium–zinc oxide thin-film transistors with SiNx/SiO2/SiNx/SiO2 passivation layers

    International Nuclear Information System (INIS)

    Chen, Rongsheng; Zhou, Wei; Zhang, Meng; Kwok, Hoi-Sing

    2014-01-01

    Self-aligned top-gate amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) with SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed in this paper. The resulting a-IGZO TFT exhibits high reliability against bias stress and good electrical performance including field-effect mobility of 5 cm 2 /Vs, threshold voltage of 2.5 V, subthreshold swing of 0.63 V/decade, and on/off current ratio of 5 × 10 6 . With scaling down of the channel length, good characteristics are also obtained with a small shift of the threshold voltage and no degradation of subthreshold swing. The proposed a-IGZO TFTs in this paper can act as driving devices in the next generation flat panel displays. - Highlights: • Self-aligned top-gate indium–gallium–zinc oxide thin-film transistor is proposed. • SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed. • The source/drain areas are hydrogen-doped by CHF3 plasma. • The devices show good electrical performance and high reliability against bias stress

  12. Back-contacted BaSi

    NARCIS (Netherlands)

    Vismara, R.; Isabella, O.; Zeman, M.

    2017-01-01

    We present the optical investigation of a novel back-contacted architecture for solar cells based on a thin barium (di)silicide (BaSi2) absorber. First, through the analysis of absorption limits of different semiconducting materials, we show the potential of BaSi2 for

  13. Natural 32Si as environmental tracer

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2005-01-01

    There is a pressing need for an effective dating tool to cover the historical past. Cosmogenic 32 Si, with a half-life of ca. 140 years, is ideally suited to provide time information in the range 50-1000 years. Detection of 32 Si is, however, very difficult due to extremely low natural concentrations and isotopic ratios. (author). 2 refs

  14. SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

    Science.gov (United States)

    Chanadee, Tawat

    2017-11-01

    Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

  15. Low-temperature Au/a-Si wafer bonding

    International Nuclear Information System (INIS)

    Jing, Errong; Xiong, Bin; Wang, Yuelin

    2011-01-01

    The Si/SiO 2 /Ti/Au–Au/Ti/a-Si/SiO 2 /Si bonding structure, which can also be used for the bonding of non-silicon material, was investigated for the first time in this paper. The bond quality test showed that the bond yield, bond repeatability and average shear strength are higher for this bonding structure. The interfacial microstructure analysis indicated that the Au-induced crystallization of the amorphous silicon process leads to big Si grains extending across the bond interface and Au filling the other regions of the bond interface, which result into a strong and void-free bond interface. In addition, the Au-induced crystallization reaction leads to a change in the IR images of the bond interface. Therefore, the IR microscope can be used to evaluate and compare the different bond strengths qualitatively. Furthermore, in order to verify the superiority of the bonding structure, the Si/SiO 2 /Ti/Au–a-Si/SiO 2 /Si (i.e. no Ti/Au layer on the a-Si surface) and Si/SiO 2 /Ti/Au–Au/Ti/SiO 2 /Si bonding structures (i.e. Au thermocompression bonding) were also investigated. For the Si/SiO 2 /Ti/Au–a-Si/SiO 2 /Si bonding structure, the poor bond quality is due to the native oxide layer on the a-Si surface, and for the Si/SiO 2 /Ti/Au–Au/Ti/SiO 2 /Si bonding structure, the poor bond quality is caused by the wafer surface roughness which prevents intimate contact and limits the interdiffusion at the bond interface.

  16. Gas-source molecular beam epitaxy of Si(111) on Si(110) substrates by insertion of 3C-SiC(111) interlayer for hybrid orientation technology

    Energy Technology Data Exchange (ETDEWEB)

    Bantaculo, Rolando, E-mail: rolandobantaculo@yahoo.com; Saitoh, Eiji; Miyamoto, Yu; Handa, Hiroyuki; Suemitsu, Maki

    2011-11-01

    A method to realize a novel hybrid orientations of Si surfaces, Si(111) on Si(110), has been developed by use of a Si(111)/3C-SiC(111)/Si(110) trilayer structure. This technology allows us to use the Si(111) portion for the n-type and the Si(110) portion for the p-type channels, providing a solution to the current drive imbalance between the two channels confronted in Si(100)-based complementary metal oxide semiconductor (CMOS) technology. The central idea is to use a rotated heteroepitaxy of 3C-SiC(111) on Si(110) substrate, which occurs when a 3C-SiC film is grown under certain growth conditions. Monomethylsilane (SiH{sub 3}-CH{sub 3}) gas-source molecular beam epitaxy (GSMBE) is used for this 3C-SiC interlayer formation while disilane (Si{sub 2}H{sub 6}) is used for the top Si(111) layer formation. Though the film quality of the Si epilayer leaves a lot of room for betterment, the present results may suffice to prove its potential as a new technology to be used in the next generation CMOS devices.

  17. Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

    International Nuclear Information System (INIS)

    Wang Qudong; Chen Yongjun; Chen Wenzhou; Wei Yinhong; Zhai Chunquan; Ding Wenjiang

    2005-01-01

    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 Mg 2 Si and a litter blocky primary Si, middle layer contains without primary Mg 2 Si and primary Si, outer layer contains primary Mg 2 Si and primary Si. The position, quantity and distribution of primary Mg 2 Si 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 Mg 2 Si and make primary Mg 2 Si 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 Mg 2 Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing

  18. Afectividad como mediador de la relación entre optimismo y calidad de vida en hombres que tienen sexo con hombres con VIH

    Directory of Open Access Journals (Sweden)

    Pablo Vera-Villarroel

    2016-01-01

    Full Text Available Antecedente/Objetivos : El aumento de la esperanza de vida ha hecho de la calidad de vida (CV el objetivo fundamental en el cuidado de pacientes crónicos y en personas que viven con VIH. Se ha encontrado evidencia del vínculo entre optimismo, calidad de vida y bienestar. El propósito del presente estudio fue determinar si la afectividad en sus dos dimensiones (positiva y negativa desempeña un rol mediador en la asociación entre op - timismo y calidad de vida en hombres viviendo con VIH que tienen sexo con hombres. Método : Ciento dieciséis hombres con VIH (edad promedio de 36,8 años; DT = 9,06; tiem - po medio desde el diagnóstico de 8,2 años contestaron tres instrumentos: Life Orientation Test Revised Version (LOT-R, Positive and Negative Affect Schedule (PANAS y World Health Organization Quality of Life-Bref (WHOQoL-Bref. Resultados : Los resultados mostraron que el afecto positivo no tuvo efecto mediador, mientras el afecto negativo medió la relación entre optimismo y dos dimensiones de la calidad de vida (calidad de vida general y ambiente. Conclusiones : Se encontró que el afecto negativo participa parcialmente como una variable mediadora entre el optimismo y calidad de vida.

  19. Diffusion in ordered Fe-Si alloys

    International Nuclear Information System (INIS)

    Sepiol, B.; Vogl, G.

    1995-01-01

    The measurement of the diffusional Moessbauer line broadening in single crystalline samples at high temperatures provides microscopic information about atomic jumps. We can separate jumps of iron atoms between the various sublattices of Fe-Si intermetallic alloys (D0 3 structure) and measure their frequencies. The diffusion of iron in Fe-Si samples with Fe concentrations between 75 and 82 at% shows a drastic composition dependence: the jump frequency and the proportion between jumps on Fe sublattices and into antistructure (Si) sublattice positions change greatly. Close to Fe 3 Si stoichiometry iron diffusion is extremely fast and jumps are performed exclusively between the three Fe sublattices. The change in the diffusion process when changing the alloy composition from stoichiometric Fe 3 Si to the iron-rich side is discussed. (orig.)

  20. DLC-Si protective coatings for polycarbonates

    Directory of Open Access Journals (Sweden)

    Damasceno J.C.

    2003-01-01

    Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

  1. SiC for microwave power transistors

    Energy Technology Data Exchange (ETDEWEB)

    Sriram, S.; Siergiej, R.R.; Clarke, R.C.; Agarwal, A.K.; Brandt, C.D. [Northrop Grumman Sci. and Technol. Center, Pittsburgh, PA (United States)

    1997-07-16

    The advantages of SiC for high power, microwave devices are discussed. The design considerations, fabrication, and experimental results are described for SiC MESFETs and SITs. The highest reported f{sub max} for a 0.5 {mu}m MESFET using semi-insulating 4H-SiC is 42 GHz. These devices also showed a small signal gain of 5.1 dB at 20 GHz. Other 4H-SiC MESFETs have shown a power density of 3.3 W/mm at 850 MHz. The largest SiC power transistor reported is a 450 W SIT measured at 600 MHz. The power output density of this SIT is 2.5 times higher than that of comparable silicon devices. SITs have been designed to operate as high as 3.0 GHz, with a 3 cm periphery part delivering 38 W of output power. (orig.) 28 refs.

  2. Pseudomorphic GeSiSn, SiSn and Ge layers in strained heterostructures

    Science.gov (United States)

    Timofeev, V. A.; Nikiforov, A. I.; Tuktamyshev, A. R.; Mashanov, V. I.; Loshkarev, I. D.; Bloshkin, A. A.; Gutakovskii, A. K.

    2018-04-01

    The GeSiSn, SiSn layer growth mechanisms on Si(100) were investigated and the kinetic diagrams of the morphological GeSiSn, SiSn film states in the temperature range of 150 °C-450 °C at the tin content from 0% to 35% were built. The phase diagram of the superstructural change on the surface of Sn grown on Si(100) in the annealing temperature range of 0 °C-850 °C was established. The specular beam oscillations were first obtained during the SiSn film growth from 150 °C to 300 °C at the Sn content up to 35%. The transmission electron microscopy and x-ray diffractometry data confirm the crystal perfection and the pseudomorphic GeSiSn, SiSn film state, and also the presence of smooth heterointerfaces between GeSiSn or SiSn and Si. The photoluminescence for the multilayer periodic GeSiSn/Si structures in the range of 0.6-0.8 eV was detected. The blue shift with the excitation power increase is observed suggesting the presence of a type II heterostructure. The creation of tensile strained Ge films, which are pseudomorphic to the underlying GeSn layer, is confirmed by the results of the formation and analysis of the reciprocal space map in the x-ray diffractometry. The tensile strain in the Ge films reached the value in the range of 0.86%-1.5%. The GeSn buffer layer growth in the Sn content range from 8% to 12% was studied. The band structure of heterosystems based on pseudomorphic GeSiSn, SiSn and Ge layers was calculated and the valence and conduction band subband position dependences on the Sn content were built. Based on the calculation, the Sn content range in the GeSiSn, SiSn, and GeSn layers, which corresponds to the direct bandgap GeSiSn, SiSn, and Ge material, was obtained.

  3. Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

    DEFF Research Database (Denmark)

    Pankratov, V.; Osinniy, Viktor; Kotlov, A.

    2011-01-01

    done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence properties of the embedded Si nanocrystals...... is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO2....

  4. Luminescence of solar cells with a-Si:H/c-Si heterojunctions

    Science.gov (United States)

    Zhigunov, D. M.; Il'in, A. S.; Forsh, P. A.; Bobyl', A. V.; Verbitskii, V. N.; Terukov, E. I.; Kashkarov, P. K.

    2017-05-01

    We have studied the electroluminescence (EL) and photoluminescence (PL) of solar cells containing a-Si:H/c-Si heterojunctions. It is established that both the EL and PL properties of these cells are determined by the radiative recombination of nonequilibrium carriers in crystalline silicon (c-Si). The external EL energy yield (efficiency) of solar cells with a-Si:H/c-Si heterojunctions at room temperature amounts to 2.1% and exceeds the value reached in silicon diode structures. This large EL efficiency can be explained by good passivation of the surface of crystalline silicon and the corresponding increase in lifetime of minority carrier s in these solar cells.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. 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

    OpenAIRE

    Lorena Torres Ronda; Joan Solé Fortó; Lisímaco Vallejo Cuéllar; Xavier Balius Matas

    2010-01-01

    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 medicione...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. La discapacidad entre poblaciones refugiadas y afectadas por conflictos

    OpenAIRE

    Reilly, Rachael

    2010-01-01

    La Comisión de Mujeres Refugiadas lanzó en el año 2007 un importante proyecto de investigación para evaluar la situación de las personas con discapacidad entre las poblaciones desplazadas o afectadas por conflictos.

  11. Positron annihilation in SiO 2-Si studied by a pulsed slow positron beam

    Science.gov (United States)

    Suzuki, R.; Ohdaira, T.; Uedono, A.; Kobayashi, Y.

    2002-06-01

    Positron and positronium (Ps) behavior in SiO 2-Si have been studied by means of positron annihilation lifetime spectroscopy (PALS) and age-momentum correlation (AMOC) spectroscopy with a pulsed slow positron beam. The PALS study of SiO 2-Si samples, which were prepared by a dry-oxygen thermal process, revealed that the positrons implanted in the Si substrate and diffused back to the interface do not contribute to the ortho-Ps long-lived component, and the lifetime spectrum of the interface has at least two components. From the AMOC study, the momentum distribution of the ortho-Ps pick-off annihilation in SiO 2, which shows broader momentum distribution than that of crystalline Si, was found to be almost the same as that of free positron annihilation in SiO 2. A varied interface model was proposed to interpret the results of the metal-oxide-semiconductor (MOS) experiments. The narrow momentum distribution found in the n-type MOS with a negative gate bias voltage could be attributed to Ps formation and rapid spin exchange in the SiO 2-Si interface. We have developed a two-dimensional positron lifetime technique, which measures annihilation time and pulse height of the scintillation gamma-ray detector for each event. Using this technique, the positronium behavior in a porous SiO 2 film, grown by a sputtering method, has been studied.

  12. Improving Passivation Process of Si Nanocrystals Embedded in SiO2 Using Metal Ion Implantation

    Directory of Open Access Journals (Sweden)

    Jhovani Bornacelli

    2013-01-01

    Full Text Available We studied the photoluminescence (PL of Si nanocrystals (Si-NCs embedded in SiO2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm inside the SiO2 achieving a robust and better protected system. After metal ion implantation (Ag or Au, and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2 and Ar to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  13. First-principles calculations of orientation dependence of Si thermal oxidation based on Si emission model

    Science.gov (United States)

    Nagura, Takuya; Kawachi, Shingo; Chokawa, Kenta; Shirakawa, Hiroki; Araidai, Masaaki; Kageshima, Hiroyuki; Endoh, Tetsuo; Shiraishi, Kenji

    2018-04-01

    It is expected that the off-state leakage current of MOSFETs can be reduced by employing vertical body channel MOSFETs (V-MOSFETs). However, in fabricating these devices, the structure of the Si pillars sometimes cannot be maintained during oxidation, since Si atoms sometimes disappear from the Si/oxide interface (Si missing). Thus, in this study, we used first-principles calculations based on the density functional theory, and investigated the Si emission behavior at the various interfaces on the basis of the Si emission model including its atomistic structure and dependence on Si crystal orientation. The results show that the order in which Si atoms are more likely to be emitted during thermal oxidation is (111) > (110) > (310) > (100). Moreover, the emission of Si atoms is enhanced as the compressive strain increases. Therefore, the emission of Si atoms occurs more easily in V-MOSFETs than in planar MOSFETs. To reduce Si missing in V-MOSFETs, oxidation processes that induce less strain, such as wet or pyrogenic oxidation, are necessary.

  14. EFFECT OF THE Si POWDER ADDITIONS ON THE PROPERTIES OF SiC COMPOSITES

    Directory of Open Access Journals (Sweden)

    GUOGANG XU

    2012-09-01

    Full Text Available By means of transient plastic phase process, the SiC silicon carbide kiln furniture materials were produced through adding Si powder to SiC materials. At the condition of the same additions of SiO2 powder, the effect of the Si powder additions on properties of silicon carbide materials after sintered at 1450°C for 3 h in air atmosphere was studied by means of SEM and other analysis methods. The results showed that silicon powder contributes to both sintering by liquid state and plastic phase combination to improve the strength of samples. When the Si powder additions is lower than 3.5 %, the density and strength of samples increase and porosity decrease with increasing Si powder additions. However when the Si powder additions is higher than 3.5 %, the density and strength of samples decrease and porosity increase with increasing Si powder additions. With increasing of Si additions, the residual strength of sample after thermal shocked increased and linear change rate decreased, and get to boundary value when Si additions is 4.5 %. The results also indicated that at the same sintering temperature, the sample with 3.5 % silicon powder has maximum strength.

  15. Uniform Si nano-dot fabrication using reconstructed structure of Si(110)

    Science.gov (United States)

    Yano, Masahiro; Uozumi, Yuki; Yasuda, Satoshi; Asaoka, Hidehito

    2018-06-01

    Si nano-dot (ND) formation on Si(110) is observed by means of a scanning tunneling microscope (STM). The initial Si-NDs are Si crystals that are continuous from the substrate and grow during the oxide layer desorption. The NDs fabricated on the flat surface of Si(110)-1 × 1 are surrounded by four types of facets with almost identical appearance probabilities. An increase in the size of the NDs increases the variety of its morphology. In contrast, most Si-NDs fabricated on straight-stepped surface of Si(110)-16 × 2 reconstructed structure are surrounded by only a single type of facet, namely the \\text{Si}(17,15,1)-2 × 1 plane. An appearance probability of the facet in which the base line is along the step of Si(110)-16 × 2 exceeds 75%. This finding provides a fabrication technique of uniformed structural Si-NDs by using the reconstructed structure of Si(110).

  16. Preparation and Characterization of SiO2/SiCN Core-shell Ceramic Microspheres

    Directory of Open Access Journals (Sweden)

    ZHANG Hai-yuan

    2017-05-01

    Full Text Available The SiO2/PSN core-shell microspheres were prepared via an emulsion reaction combined with the polymer-derived ceramics (PDCs method using polysilazane (PSN in situ polymerization on the surface of SiO2 modified by silane coupling agents MPS, followed by pyrolysis process to obtain SiO2/SiCN core-shell ceramic microspheres. The effects of raw mass ratio, curing time and pyrolysis temperature on the formation and the morphology of core-shell microspheres were studied. The morphology, chemical composition and phase transformation were characterized by SEM, EDS, TEM, FT-IR and XRD. The results show that after reaction for 4h at 200℃, SiO2 completely coated PSN forms a core-shell microsphere with rough surface when the mass ratio of SiO2 and PSN is 1:4; when pyrolysis temperature is at 800-1200℃, amorphous SiO2/SiCN core-shell ceramic microspheres are prepared; at 1400℃, the amorphous phase partially crystallizes to produce SiO2, SiC and Si3N4 phase.

  17. Neutron tolerance of advanced SiC-fiber/CVI-SiC composites

    International Nuclear Information System (INIS)

    Katoh, Y.; Kohyama, A.; Snead, L.L.; Hinoki, T.; Hasegawa, A.

    2003-01-01

    Fusion blankets employing a silicon carbide (SiC) fiber-reinforced SiC matrix composite (SiC/SiC composite) as the structural material provide attractive features represented by high cycle efficiency and extremely low induced radioactivity. Recent advancement in processing and utilization techniques and application studies in ceramic gas turbine and advanced transportation systems, SiC/SiC composites are steadily getting matured as industrial materials. Reference SiC/SiC composites for fusion structural applications have been produced by a forced-flow chemical vapor infiltration (FCVI) method using conventional and advanced near-stoichiometric SiC fibers and extensively evaluated primarily in Japan-US collaborative JUPITER program. In this work, effect of neutron irradiation at elevated temperatures on mechanical property of these composites is characterized. Unlike in conventional SiC/SiC composites, practically no property degradation was identified in advanced composites with a thin carbon interphase by a neutron fluence level of approximately 8dpa at 800C. (author)

  18. Time-resolved photoluminescence of SiOx encapsulated Si

    Science.gov (United States)

    Kalem, Seref; Hannas, Amal; Österman, Tomas; Sundström, Villy

    Silicon and its oxide SiOx offer a number of exciting electrical and optical properties originating from defects and size reduction enabling engineering new electronic devices including resistive switching memories. Here we present the results of photoluminescence dynamics relevant to defects and quantum confinement effects. Time-resolved luminescence at room temperature exhibits an ultrafast decay component of less than 10 ps at around 480 nm and a slower component of around 60 ps as measured by streak camera. Red shift at the initial stages of the blue luminescence decay confirms the presence of a charge transfer to long lived states. Time-correlated single photon counting measurements revealed a life-time of about 5 ns for these states. The same quantum structures emit in near infrared close to optical communication wavelengths. Nature of the emission is described and modeling is provided for the luminescence dynamics. The electrical characteristics of metal-oxide-semiconductor devices were correlated with the optical and vibrational measurement results in order to have better insight into the switching mechanisms in such resistive devices as possible next generation RAM memory elements. ``This work was supported by ENIAC Joint Undertaking and Laser-Lab Europe''.

  19. Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

    Institute of Scientific and Technical Information of China (English)

    蔡艳芝; 殷小玮; 尹洪峰

    2015-01-01

    The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

  20. Investigation on fabrication of SiC/SiC composite as a candidate material for fuel sub-assembly

    International Nuclear Information System (INIS)

    Lee, Jae-Kwang; Naganuma, Masayuki; Park, Joon-Soo; Kohyama, Akira

    2005-01-01

    The possibility of SiC/SiC (Silicon carbide fiber reinforced Silicon carbide) composites application for fuel sub-assembly of Fast Breeder Reactor was investigated. To select a raw material of SiC/SiC composites, a few kinds of SiC nano powder was estimated by SEM observation and XRD analysis. Furthermore, SiC monolithic was sintered from them and estimated by flexural test. SiC nano-powder which showed good sinterability, it was used for fabrication of SiC/SiC composites by Hot Pressing method. From the sintering condition of 1800, 1820degC temperature and 15, 20 MPa pressure, SiC/SiC composite was fabricated and then estimated by tensile test. SiC/SiC composite, which made by 1820degC and 20 MPa condition, showed the highest mechanical strength by the monotonic tensile test. SiC/SiC composite, which made by 1800degC and 15 MPa condition, showed a stable fracture behavior at the monotonic and cyclic tensile test. And then, the hoop stress of ideal model of SiC/SiC composites was discussed. It was confirmed that applicability of SiC/SiC composites by Hot Pressing method for fuel sub-assembly structural material. To make it real attractive one, to maintain the reliability and safety as a high temperature structural material, the design and process study on SiC/Sic composites material will be continued. (author)

  1. Positron annihilation spectroscopy of the interface between nanocrystalline Si and SiO2

    International Nuclear Information System (INIS)

    Pi, X.D.; Coleman, P.G.; Harding, R.; Davies, G.; Gwilliam, R.M.; Sealy, B.J.

    2003-01-01

    Positron annihilation spectroscopy has been employed to study changes in the interface region between nanocrystalline Si and SiO 2 , following annealing between 400 deg. C and 900 deg. C in nitrogen or oxygen. With the support of photoluminescence spectroscopy we find that nitrogen and oxygen are trapped in voids at the interface at low temperatures. At temperatures above 700 deg. C both nitrogen and oxygen react with Si nanocrystals, and the resulting volume increase introduces stress in the SiO 2 matrix which is relaxed by the shrinkage of its intrinsic open volume. Oxygen appears to enhance Si diffusion in SiO 2 so that the agglomeration of Si nanocrystals occurs more readily during annealing in oxygen than in nitrogen

  2. Thickness dependent formation and properties of GdSi2/Si(100) interfaces

    International Nuclear Information System (INIS)

    Peto, G.; Molnar, G.; Dozsa, L.; Horvath, Z.E.; Horvath, Zs.J.; Zsoldos, E.; Dimitriadis, C.A.; Papadimitriou, L.

    2005-01-01

    Epitaxial and polycrystalline orthorhombic GdSi 2 films were grown on Si(100) substrates by solid phase reaction between Si and Gd films at different thicknesses of the Gd film. The most important property of these GdSi 2 /Si interfaces was defect formation. This was investigated by studying the properties of the Schottky barriers by means of current voltage and capacitance-voltage characteristics, deep level transient spectroscopy by double crystal X-ray diffractometry, and transmission electron microscopy. Epitaxial growth of the silicide layer ensured a relatively low interface defect density (about 10 10 cm -2 ), while the non-epitaxial growth induced defects of a much higher density (about 10 12 cm -2 ). The defects generated during the silicide formation are located within a depth of about 10 nm from the GdSi 2 /Si interface. (orig.)

  3. Structural and electrical evaluation for strained Si/SiGe on insulator

    International Nuclear Information System (INIS)

    Wang Dong; Ii, Seiichiro; Ikeda, Ken-ichi; Nakashima, Hideharu; Ninomiya, Masaharu; Nakamae, Masahiko; Nakashima, Hiroshi

    2006-01-01

    Three strained Si/SiGe on insulator wafers having different Ge fractions were evaluated using dual-metal-oxide-semiconductor (dual-MOS) deep level transient spectroscopy (DLTS) and transmission electron microscopy (TEM) methods. The interface of SiGe/buried oxide (BOX) shows roughness less than 1 nm by high resolution TEM observation. The interface states densities (D it ) of SiGe/BOX are approximately 1 x 10 12 cm -2 eV -1 , which is approximately one order of magnitude higher than that of Si/BOX in a Si on insulator wafer measured as reference by the same method of dual-MOS DLTS. The high D it of SiGe/BOX is not due to interface roughness but due to Ge atoms. The threading dislocations were also clearly observed by TEM and were analyzed

  4. Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

    Science.gov (United States)

    Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

    2017-04-01

    Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

  5. Silicon Effects on Properties of Melt Infiltrated SiC/SiC Composites

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Gyekenyesi, John Z.; Hurst, Janet B.

    2000-01-01

    Silicon effects on tensile and creep properties, and thermal conductivity of Hi-Nicalon SiC/SiC composites have been investigated. The composites consist of 8 layers of 5HS 2-D woven preforms of BN/SiC coated Hi-Nicalon fiber mats and a silicon matrix, or a mixture of silicon matrix and SiC particles. The Hi-Nicalon SiC/silicon and Hi-Nicalon SiC/SiC composites contained about 24 and 13 vol% silicon, respectively. Results indicate residual silicon up to 24 vol% has no significant effect on creep and thermal conductivity, but does decrease the primary elastic modulus and stress corresponding to deviation from linear stress-strain behavior.

  6. Structural and photoluminescence properties of Si-based nanosheet bundles rooted on Si substrates

    Science.gov (United States)

    Yuan, Peiling; Tamaki, Ryo; Kusazaki, Shinya; Atsumi, Nanae; Saito, Yuya; Kumazawa, Yuki; Ahsan, Nazmul; Okada, Yoshitaka; Ishida, Akihiro; Tatsuoka, Hirokazu

    2018-04-01

    Si-based nanosheet bundles were synthesized by the extraction of Ca atoms from CaSi2 microwalls grown on Si substrates by inositol hexakisphosphate solution or thermal treatment in FeCl2 vapor. The structural and photoluminescence properties of the Si-based nanosheet bundles were examined. The photoluminescence emissions in the visible region were clearly observed, and the temperature and excitation intensity dependences of the emissions were characterized. The observed Si-based nanosheets consist of thin Si layers, and a superlattice-like layered structural model is proposed to describe the Si-based nanosheet bundle structures and their photoluminescence property. The photoluminescence property of the nanosheets significantly depends on their treatment process. The luminescence mechanism of the nanosheets was discussed.

  7. Light emissions from LiNbO sub 3 /SiO sub 2 /Si structures

    CERN Document Server

    Wu, X L; Tang, N; Deng, S S; Bao, X M

    2003-01-01

    LiNbO sub 3 (LN) films with a high degree of (006) texture were deposited on Si-based dense SiO sub 2 layers by pulsed laser deposition. After annealing, the LN/SiO sub 2 /Si structures were revealed to have ultraviolet-, green-, and red-emitting properties related to self-trapped excitons and E' defect pairs in the SiO sub 2 surface, which are induced by the photorefractive effect of the LN films. The emission wavelength can be tuned by introducing different dopants into the LN films. Waveguiding properties of the structures were demonstrated. The results obtained indicate that the LN/SiO sub 2 /Si structures could be expected to have important applications in modern optoelectronic integration. (letter to the editor)

  8. Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

    International Nuclear Information System (INIS)

    Rivas Mercury, J.M.; Pena, P.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

    2007-01-01

    Partially deuterated Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x hydrates prepared by a reaction in the presence of D 2 O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29 Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x was followed by 27 Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 5 environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data

  9. Isotopic effects in sub-barrier fusion of Si + Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

    2018-04-01

    Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion

  10. Mushroom-free selective epitaxial growth of Si, SiGe and SiGe:B raised sources and drains

    Science.gov (United States)

    Hartmann, J. M.; Benevent, V.; Barnes, J. P.; Veillerot, M.; Lafond, D.; Damlencourt, J. F.; Morvan, S.; Prévitali, B.; Andrieu, F.; Loubet, N.; Dutartre, D.

    2013-05-01

    We have evaluated various Cyclic Selective Epitaxial Growth/Etch (CSEGE) processes in order to grow "mushroom-free" Si and SiGe:B Raised Sources and Drains (RSDs) on each side of ultra-short gate length Extra-Thin Silicon-On-Insulator (ET-SOI) transistors. The 750 °C, 20 Torr Si CSEGE process we have developed (5 chlorinated growth steps with four HCl etch steps in-between) yielded excellent crystalline quality, typically 18 nm thick Si RSDs. Growth was conformal along the Si3N4 sidewall spacers, without any poly-Si mushrooms on top of unprotected gates. We have then evaluated on blanket 300 mm Si(001) wafers the feasibility of a 650 °C, 20 Torr SiGe:B CSEGE process (5 chlorinated growth steps with four HCl etch steps in-between, as for Si). As expected, the deposited thickness decreased as the total HCl etch time increased. This came hands in hands with unforeseen (i) decrease of the mean Ge concentration (from 30% down to 26%) and (ii) increase of the substitutional B concentration (from 2 × 1020 cm-3 up to 3 × 1020 cm-3). They were due to fluctuations of the Ge concentration and of the atomic B concentration [B] in such layers (drop of the Ge% and increase of [B] at etch step locations). Such blanket layers were a bit rougher than layers grown using a single epitaxy step, but nevertheless of excellent crystalline quality. Transposition of our CSEGE process on patterned ET-SOI wafers did not yield the expected results. HCl etch steps indeed helped in partly or totally removing the poly-SiGe:B mushrooms on top of the gates. This was however at the expense of the crystalline quality and 2D nature of the ˜45 nm thick Si0.7Ge0.3:B recessed sources and drains selectively grown on each side of the imperfectly protected poly-Si gates. The only solution we have so far identified that yields a lesser amount of mushrooms while preserving the quality of the S/D is to increase the HCl flow during growth steps.

  11. Relación entre las Competencias Laborales de los Servidores y la Calidad en el Servicio Percibida por los Usuarios/Clientes

    OpenAIRE

    López Carrilles, Angélica B.

    2004-01-01

    A lo largo de la investigación, se presenta el proceso para determinar si existe una relación entre las competencias laborales de los servidores y la calidad en el servicio que los usuarios/clientes perciben al recibir el servicio En el Capítulo I de la investigación se presenta lo relacionado con el tema de la investigación, el marco teórico sobre calidad, calidad en el servicio, así como también características de las personas y competencias, algunas clasificaciones de éstas Últimas y toda ...

  12. A distinção entre o sentido negativo e positivo da liberdade na Fundamentação da Metafísica dos Costumes

    OpenAIRE

    Hipolito, Marco André de Freitas

    2011-01-01

    O presente trabalho pretende analisar a distinção entre o conceito de liberdade em sentido negativo e o de liberdade em sentido positivo, enfatizando, também, os conceitos que Kant utiliza para fundamentar a moral sob a idéia da liberdade em sentido positivo. No primeiro capítulo analisamos a tese kantiana de que somente mediante uma boa vontade haveria a possibilidade de agir moralmente. A boa vontade é tida por Kant como um princípio do querer, que deve ser determinado por si...

  13. ¿Chindia o China más India? : complementariedad y competencia económicas entre dos gigantes asiáticos

    OpenAIRE

    Bustelo Gómez, Pablo

    2010-01-01

    Este trabajo explora si las economías de China y de la India son y van a ser fundamentalmente complementarias (el escenario Chindia) o, por el contrario, esencialmente competitivas (el escenario China + India) entre ellas. En el primer caso, los efectos podrían ser un desplazamiento más rápido hacia Asia del centro de gravedad de la economía mundial y quizás la aparición de un nuevo tipo de globalización, alternativa basada en la hegemonía de Occidente. En el segundo, esos efectos se verían r...

  14. Relación entre hiperlaxitud articular, dismetría de miembros inferiores y control postural con los trastornos posturales

    OpenAIRE

    Farro-Uceda, Luis; Tapia-Egoavil, Raquel; Valverde-Tarazona, César; Bautista-Chirinos, Luz; Amaya-Solis, Karen

    2016-01-01

    Objetivos: Determinar si existe relación entre hiperlaxitud articular, dismetría de miembros inferiores y la estabilidad o control postural en bipedestación con los trastornos posturales en adolescentes. Material y métodos: Estudio relacional-transversal, realizado en el Instituto Nacional de Rehabilitación “Dra. Adriana Rebaza Flores” Amistad Perú-Japón, Chorrillos-Perú. Participaron todos los estudiantes del 5º año de secundaria de un colegio privado de la ciudad de Lima. La hiperlaxitud ar...

  15. Relación entre hiperlaxitud articular, dismetría de miembros inferiores y control postural con los trastornos posturales

    OpenAIRE

    Farro-Uceda, Luis; Tapia-Egoavil, Raquel; Valverde-Tarazona, César; Bautista-Chirinos, Luz; Amaya-Solis, Karen

    2017-01-01

    Objetivos: Determinar si existe relación entre hiperlaxitud articular, dismetría de miembros inferiores y la estabilidad o control postural en bipedestación con los trastornos posturales en adolescentes. Material y métodos: Estudio relacionaltransversal, realizado en el Instituto Nacional de Rehabilitación “Dra. Adriana Rebaza Flores” Amistad Perú-Japón,Chorrillos-Perú. Participaron todos los estudiantes del 5º año de secundaria de un colegio privado de la ciudad de Lima. La hiperlaxitud arti...

  16. Estudio de viabilidad para la ejecución de un aparcamiento subterráneo entre las calles Ciudad de Granada, Bolivia y Badajoz de Barcelona

    OpenAIRE

    Domínguez Quinoya, Inmaculada

    2014-01-01

    Este trabajo, punto final a los estudios de Ciencias y Tecnología de Edificación, pretende aplicar todos los conocimientos adquiridos en estos cuatro años en un proyecto concreto y real. Se trata de confirmar o negar la viabilidad de la construcción de un aparcamiento subterráneo en un solar situado entre las calles Ciudad de Granada, Bolivia y Badajoz de Barcelona. 1.- VIABILIDAD EN EL TERRITORIO: Empezamos conociendo la zona donde se ubica el aparcamiento, estudiando si ex...

  17. Correlación entre bilirrubina serica y bilirrubinometría transcutánea en neonatos estratificados por edad gestacional

    OpenAIRE

    Furzán, Jaime A; Expósito, Mercedes; Luchón, Consuelo

    2007-01-01

    Introducción: La ictericia neonatal es un dilema diagnóstico y terapéutico muy común. Las decisiones basadas en mediciones seriadas de bilirrubina sérica se asocian con dolor en el niño, tiempo de espera y ansiedad por los resultados. La bilirrubinometría transcutánea puede ser una alternativa confiable si se demuestra su validez para poblaciones e instituciones particulares. Objetivos: Establecer el grado de correlación entre bilirrubina sérica total (BST) y bilirrubina transcutánea (BTC) en...

  18. LA RELACIÓN ENTRE LA RELIGIÓN REVELADA Y LA RELIGIÓN RACIONAL EN IMMANUEL KANT.

    Directory of Open Access Journals (Sweden)

    Luis Tapia

    2012-06-01

    Full Text Available El presente artículo se centra en el estudio de la filosofía de Kant en el ámbito religioso y, de manera específica, en la relación que puede establecerse entre la religión revelada y lo que Kant propone como religión racional. Se busca establecer si con la noción de religión racional quedan superadas, y negadas como caminos viables, las religiones históricas concretas. Se destaca cómo, en el pensamiento de Kant, la religión revelada existe en función de la religión racional, como un medio o vehículo hacia ella.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. A natureza humana do comportamento individual nos primórdios do pensamento econômico: uma comparação entre Hume, Smith e Bentham

    Directory of Open Access Journals (Sweden)

    Glaucia Campregher

    Full Text Available Resumo Busca-se compreender como a relação entre indivíduo e contexto social-histórico fazia-se presente nas teorias e especulações filosóficas de Hume, Smith e Bentham - enfocando o papel concedido à natureza individual, suas supostas tendências ou predisposições inatas, sejam elas racionais ou passionais. Principalmente em Hume e Smith, observa-se que a capacidade natural de nos importarmos com o outro, sympathy, não diz muito em si mesma, mas ganha concretude com o hábito. Já em Bentham, a sympathy, que faz o indivíduo sair de si e se reconhecer no outro, dará lugar ao indivíduo isolado, o que impossibilita a superação de uma “natureza natural” por uma natureza histórico-social do homem.

  1. Luminescence properties of Si-capped β-FeSi{sub 2} nanodots epitaxially grown on Si(001) and (111) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Amari, Shogo; Ichikawa, Masakazu [Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

    2014-02-28

    We studied the luminescence properties of Si-capped β-FeSi{sub 2} nanodots (NDs) epitaxially grown on Si substrates by using photoluminescence (PL) and electroluminescence (EL) spectroscopies. Codepositing Fe and Si on ultrathin SiO{sub 2} films induced the self-assembly of epitaxial β-FeSi{sub 2} NDs. The PL spectra of the Si/β-FeSi{sub 2} NDs/Si structure depended on the crystal orientation of the Si substrate. These structures exhibited a broad PL peak near 0.8 eV on both Si(001) and (111) substrates. The PL intensity depended on the shape of the β-FeSi{sub 2} NDs. For the flat NDs, which exhibited higher PL intensity, we also recorded EL spectra. We explained the luminescence properties of these structures by the presence of nanostructured Si offering radiative electronic states in the Si cap layers, generated by nano-stressors for upper Si layer: the strain-relaxed β-FeSi{sub 2} NDs.

  2. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    Gueneau, C.; Ansara, I.

    1994-01-01

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

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

    Directory of Open Access Journals (Sweden)

    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.

  4. RELACIÓN ENTRE EXPERIMENTAR EVENTOS VITALES ESTRESANTES Y SU SEVERIDAD

    Directory of Open Access Journals (Sweden)

    Flora J. García-Camargo

    2016-01-01

    Full Text Available Experimentar eventos vitales predice un deterioro en la salud , pero se desconocía si dicha experiencia afecta l a magnitud de los puntajes para cuantificar el estrés. El estudio averiguó la relación entre haber experimentado eventos vitales y su severidad . Adultos (N = 670 juzgaron la severidad de eventos que habían y que no habían experimentado . Los participantes juzgaron como más severos los eventos experimentados que los no experimentados . Esto sugirió que los puntajes empleados actualmente para cuantificar e l estrés subestiman el impacto nocivo de los eventos. Las mujeres juzgaron todos los eventos como más severos que los hombres . L os jóvenes juzgaron como más severos los eventos no experimentados mientras que las personas de clase baja juzgaron como más severos que sus contrapartes los eventos que habían experimentado. Se concluyó que la asignación de puntajes de una cierta magnitud está relacionada con experimentar los sucesos y no con las características socio -demográficas de los jueces.

  5. Imaginar con tecnologías: relaciones entre tecnologías y conocimiento

    Directory of Open Access Journals (Sweden)

    Depetris, Beatriz

    2006-01-01

    Full Text Available La masiva inclusión de tecnologías en los procesos de enseñanza y de aprendizaje no está, muchas veces, precedida de la necesaria reflexión sobre los tiempos, los modos y los contextos en los que deben incorporarse. Es por ello que todo aporte que la incentive resulta sumamente valioso. Carina Lion es Doctora en Educación de la Universidad de Buenos Aires, Especialista en Formación de Formadores, Licenciada y Profesora en Ciencias de la Educación de la Facultad de Filosofía y Letras de la Universidad de Buenos Aires. Ha desarrollado una importante trayectoria docente en las áreas de educación a distancia y educación y tecnologías. Si bien este libro constituye su primera producción individual, son variadas sus publicaciones sobre las complejas relaciones entre tecnología y educación, tanto en obras colectivas como en revistas (con y sin referato, abarcando tanto cuestiones académicas como de difusión.

  6. Los juegos y deportes tradicionales en Europa: entre la tradición y la modernidad

    Directory of Open Access Journals (Sweden)

    Pere Lavega

    2006-06-01

    Full Text Available El juego es un elemento básico de socialización: es una creación cultural en el marco de una sociedad determinada. La visión contextualizada de todo juego tradicional debe considerar las propiedades que caracterizan su lógica interna, así como las condiciones socioculturales y los significados simbólicos que le atribuyen sus protagonistas (lógica externa. En esta investigación se realiza un inventario y análisis de la lógica interna y la lógica externa de los juegos tradicionales de adultos que se practican actualmente en 11 regiones europeas. Entre las conclusiones más relevantes destacar que existe un gran repertorio de juegos psicomotores y sociomotores. Se trata de juegos con un alto componente competitivo, en los que se distinguen vencedores y perdedores. Los grupos son básicamente masculinos y mixtos y sin la presencia de un líder o capitán, excepto en las regiones más deportivizadas en las que si aparece esta figura. Se observa que muchas de estas prácticas se están transformando en deportes (regionales, sobre todo aquellas que son protagonizadas por el género masculino. En definitiva, esta investigación aporta datos muy relevantes para comprender la naturaleza de la cultura lúdica tradicional europea.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Influence of SiC coating thickness on mechanical properties of SiCf/SiC composite

    Science.gov (United States)

    Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

    2013-11-01

    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 SiCf/SiC) composites were fabricated using polymer infiltration and pyrolysis (PIP) process. Influences of the fibre coating thickness on mechanical properties of SiC fibre and SiCf/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. A chemical attack of hydrogen or other ions (e.g. a C-H group) on the surface of SiC fibres during the coating process, owing to the formation of volatile hydrogen, lead to an increment of the surface defects of the fibres. This was confirmed by Wang et al. [35] in their work on the SiC coating of the carbon fibre. In the present study, the existing ˜30 nm carbon on the surface of KD-I fibre [36] made the fibre easy to be attacked. Deposition of non-stoichiometric SiC, causing a decrease in strength. During the CVD process, a small amount of free silicon or carbon always existed [35]. The existence of free silicon, either disordered the structure of SiC and formed a new source of cracks or attacked the carbon on fibre surface resulting in properties degeneration of the KD-I fibre. The effect of residual stress. The different thermal expansion coefficient between KD-I SiC fibre and CVD SiC coating, which are 3 × 10-6 K-1 (RT ˜ 1000 °C) and 4.6 × 10-6 K-1 (RT ˜ 1000 °C), respectively, could cause residual stress

  9. Cuidado de si e relações de poder: enfermeira cuidando de outras mulheres

    Directory of Open Access Journals (Sweden)

    Ana Renata Moura Rabelo

    Full Text Available RESUMO Objetivo: analisar o cuidado de si de enfermeiras e as relações de poder estabelecidas por elas no cuidado de outras mulheres. Método: revisão integrativa da literatura publicada entre os anos de 2005 e 2015. Compuseram a amostra 25 publicações. Resultados: estado da arte majoritariamente qualitativo com domínio de referenciais de uma perspectiva libertadora, pautada na humanização, autonomia e empoderamento como estratégia de redução de riscos na prática do cuidado à mulher. Os achados sugerem relações de poder solidificadas entre enfermeiras-mulheres, centradas no domínio profissional com forte concentração na formação da enfermeira sob o discurso patriarcal e de normalização da sociedade. Alguns estudos ponderam a importância da compreensão do poder na forma capilar, operando nos corpos dos indivíduos. Conclusão: há pouca discussão sobre o cuidado de si de enfermeiras e dos efeitos na sua prática profissional, indicando lacunas no conhecimento neste campo.

  10. Passivation of defect states in Si and Si/SiO2 interface states by cyanide treatment: improvement of characteristics of pin-junction amorphous Si and crystalline Si-based metal-oxide-semiconductor junction solar cells

    International Nuclear Information System (INIS)

    Fujiwara, N.; Fujinaga, T.; Niinobe, D.; Maida, O.; Takahashi, M.; Kobayashi, H.

    2003-01-01

    Defect states in Si can be passivated by cyanide treatment which simply involves immersion of Si materials in KCN solutions, followed by rinse. When the cyanide treatment is applied to pin-junction amorphous Si [a-Si] solar cells, the initial conversion efficiency increases. When the crown-ether cyanide treatment using a KCN solution of xylene containing 18-crown-6 is performed on i-a-Si films, decreases in the photo- and dark current densities with the irradiation time are prevented. The cyanide treatment can also passivate interface states present at Si/SiO 2 interfaces, leading to an increase in the conversion efficiency of 2 / Si (100)> solar cells.. Si-CN bonds formed by the reaction of defect states with cyanide ions have a high bond energy of about 4.5 eV and hence heat treatment at 800 0 C does not rupture the bonds, making thermal stability of the cyanide treatment.. When the cyanide treatment is applied to ultrathin SiO 2 /Si structure, the leakage current density is markedly decreased (Authors)

  11. Si Wire-Array Solar Cells

    Science.gov (United States)

    Boettcher, Shannon

    2010-03-01

    Micron-scale Si wire arrays are three-dimensional photovoltaic absorbers that enable orthogonalization of light absorption and carrier collection and hence allow for the utilization of relatively impure Si in efficient solar cell designs. The wire arrays are grown by a vapor-liquid-solid-catalyzed process on a crystalline (111) Si wafer lithographically patterned with an array of metal catalyst particles. Following growth, such arrays can be embedded in polymethyldisiloxane (PDMS) and then peeled from the template growth substrate. The result is an unusual photovoltaic material: a flexible, bendable, wafer-thickness crystalline Si absorber. In this paper I will describe: 1. the growth of high-quality Si wires with controllable doping and the evaluation of their photovoltaic energy-conversion performance using a test electrolyte that forms a rectifying conformal semiconductor-liquid contact 2. the observation of enhanced absorption in wire arrays exceeding the conventional light trapping limits for planar Si cells of equivalent material thickness and 3. single-wire and large-area solid-state Si wire-array solar cell results obtained to date with directions for future cell designs based on optical and device physics. In collaboration with Michael Kelzenberg, Morgan Putnam, Joshua Spurgeon, Daniel Turner-Evans, Emily Warren, Nathan Lewis, and Harry Atwater, California Institute of Technology.

  12. Joining SiC/SiC composites for fusion applications

    International Nuclear Information System (INIS)

    Henager, C.J.

    2007-01-01

    Full text of publication follows: The use of SiC-reinforced composites for fusion reactors or other nuclear applications will likely require some form of joining in order to form large structural or functional sections. Joints must be able to allow load transfer to the composite material so that the fiber reinforcements are able to carry their designed loads and the joint should not fail in a brittle manner. In addition, joints must be tolerant of radiation damage similar to the composite material to maintain the structural integrity of the joined section. Other requirements of interest are low activation joints and ease of joining application and processing, which are a difficult set of criteria to meet. Research at PNNL has been directed at high-strength joints using solid-state displacement reactions and pre-ceramic polymer joints that are easy to apply and that could be used in field repair situations. This research will report on the further development and testing of such joints using a double notch shear (DNS) specimen that is suitable for in-reactor testing. The results reveal that the solid-state joints are stronger than the polymer-based joints but require high-temperature, high-pressure processing. The polymer-based joints can be applied with reduced pressure and temperature processing compared to the solid-state joints. The polymer-based joints may have adequate strength for some applications where ease of application and in situ processing are required. Although irradiation testing is not reported in this study the use of the DNS specimen is discussed with regard to future neutron irradiations. (authors)

  13. Sodome à Paris : protohistoire de l’homosexualité masculine fin XVIIIe-milieu XIXe siècle

    OpenAIRE

    Pastorello, Thierry

    2018-01-01

    Entre la fin du XVIIIe siècle et jusqu’aux alentours du milieu du XIXe siècle, l’homosexualité masculine, comme catégorie désignant et stigmatisant certains hommes, est en voie de construction. Nous avons pris pour exemple Paris. Ce travail examine ce processus, par un croisement des discours et des vécus. Le cadre parisien offre un laboratoire suffisamment important : les faits d’homosexualité peuvent être observés à travers tout un ensemble de comportements et de pratiques identifiables dan...

  14. Quantitative détermination of aluminium and silicon in SiO2 and Al2O3 by X ray fluorescence

    Directory of Open Access Journals (Sweden)

    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.

  15. Light trapping of crystalline Si solar cells by use of nanocrystalline Si layer plus pyramidal texture

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Kentaro; Nonaka, Takaaki; Onitsuka, Yuya; Irishika, Daichi; Kobayashi, Hikaru, E-mail: h.kobayashi@sanken.osaka-u.ac.jp

    2017-02-15

    Highlights: • Ultralow reflectivity Si wafers with light trapping effect can be obtained by forming a nanocrystalline Si layer on pyramidal textured Si surfaces. • Surface passivation using phosphosilicate glass improved minority carrier lifetime of the nanocrystalline Si layer/Si structure. • A high photocurrent density of 40.1 mA/cm{sup 2}, and a high conversion efficiency of 18.5% were achieved. - Abstract: The surface structure chemical transfer (SSCT) method has been applied to fabrication of single crystalline Si solar cells with 170 μm thickness. The SSCT method, which simply involves immersion of Si wafers in H{sub 2}O{sub 2} plus HF solutions and contact of Pt catalyst with Si taking only ∼30 s for 6 in. wafers, can decrease the reflectivity to less than 3% by the formation of a nanocrystalline Si layer. However, the reflectivity of the nanocrystalline Si layer/flat Si surface/rear Ag electrode structure in the wavelength region longer than 1000 nm is high because of insufficient absorption of incident light. The reflectivity in the long wavelength region is greatly decreased by the formation of the nanocrystalline Si layer on pyramidal textured Si surfaces due to an increase in the optical path length. Deposition of phosphosilicate glass (PSG) on the nanocrystalline Si layer for formation of pn-junction does not change the ultralow reflectivity because the surface region of the nanocrystalline Si layer possesses a refractive index of 1.4 which is nearly the same as that of PSG of 1.4–1.5. The PSG layer is found to passivate the nanocrystalline Si layer, which is evident from an increase in the minority carrier lifetime from 12 to 44 μs. Hydrogen treatment at 450 °C further increases the minority carrier lifetime approximately to a doubled value. The solar cells with the Si layer/pyramidal Si substrate/boron-diffused back surface field/Ag rear electrode> structure show a high conversion efficiency of 18

  16. Microstructural optimization of high temperature SiC/SiC composites by nite process

    International Nuclear Information System (INIS)

    Shimoda, K.; Park, J.S.; Hinoki, T.; Kohyama, A.

    2007-01-01

    Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

  17. Microstructural optimization of high temperature SiC/SiC composites by nite process

    Energy Technology Data Exchange (ETDEWEB)

    Shimoda, K. [Kyoto Univ., Graduate School of Energy Science (Japan); Park, J.S. [Kyoto Univ., Institute of Advanced Energy (Japan); Hinoki, T.; Kohyama, A. [Kyoto Univ., lnstitute of Advanced Energy, Gokasho, Uji (Japan)

    2007-07-01

    Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

  18. Práticas de si de cuidadores familiares na atenção domiciliar

    Directory of Open Access Journals (Sweden)

    Bruna Ferreira Ribeiro

    2017-09-01

    Full Text Available Introdução: Atualmente há expansão de serviços de atenção domiciliar, sendo necessário que algum familiar seja o cuidador. Deste modo, é relevante compreender as práticas de si dos cuidadores familiares no contexto da atenção domiciliar. Materiais e Métodos: Pesquisa qualitativa, inserida na vertente pós-estruturalista. Participaram da pesquisa 18 cuidadores familiares de pacientes com doenças crônicas ou terminais vinculados ao serviço de atenção domiciliar de um hospital do sul do Brasil. A produção de informações ocorreu por meio de entrevista narrativa, realizada entre julho de 2015 e março de 2016. Os participantes foram entrevistados em três encontros, com periodicidade semanal. A análise se constituiu de questões elaboradas diante das informações produzidas articuladas com as teorizações foucaultianas, sobre cuidado de si, relações de poder e discurso. Resultados e Discussão: Duas categorias foram elaboradas: Constituição do sujeito cuidador: quais os discursos que o atravessam? e práticas de si como caminho de ressignificação ao cuidado. As práticas de si foram configuradas como modo de acesso a verdade, se caracterizando como fio condutor do cuidado de si, levando os cuidadores, nas suas mais diversas formas de ser, a se subjetivarem e se reconstituírem, através de si e do outro. Conclusões: Ser cuidador familiar é circundado por diversos discursos que atravessam seu modo de cuidar e que as práticas de si foram configuradas como modo de acesso a verdade. Como citar este artigo: Ribeiro BF, Oliveira SG, Tristão FSA, Santos-Júnior JRG, Farias TA. Práticas de si de cuidadores familiares na atenção domiciliar. Rev Cuid. 2017; 8(3: 1809-25. http://dx.doi.org/10.15649/cuidarte.v8i3.429

  19. Fabrication of poly-crystalline Si-based Mie resonators via amorphous Si on SiO2 dewetting.

    Science.gov (United States)

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Bidault, Sebastien; Bonod, Nicolas; Abbarchi, Marco

    2016-02-07

    We report the fabrication of Si-based dielectric Mie resonators via a low cost process based on solid-state dewetting of ultra-thin amorphous Si on SiO2. We investigate the dewetting dynamics of a few nanometer sized layers annealed at high temperature to form submicrometric Si-particles. Morphological and structural characterization reveal the polycrystalline nature of the semiconductor matrix as well as rather irregular morphologies of the dewetted islands. Optical dark field imaging and spectroscopy measurements of the single islands reveal pronounced resonant scattering at visible frequencies. The linewidth of the low-order modes can be ∼20 nm in full width at half maximum, leading to a quality factor Q exceeding 25. These values reach the state-of-the-art ones obtained for monocrystalline Mie resonators. The simplicity of the dewetting process and its cost-effectiveness opens the route to exploiting it over large scales for applications in silicon-based photonics.

  20. Characterization of SiCf/SiC and CNT/SiC composite materials produced by liquid phase sintering

    International Nuclear Information System (INIS)

    Lee, J.K.; Lee, S.P.; Cho, K.S.; Byun, J.H.; Bae, D.S.

    2011-01-01

    This paper dealt with the microstructure and mechanical properties of SiC based composites reinforced with different reinforcing materials. The composites were fabricated using reinforcing materials of carbon nanotubes (CNT) and Tyranno Lox-M SiC chopped fibers. The volume fraction of carbon nanotubes was also varied in this composite system. An Al 2 O 3 -Y 2 O 3 powder mixture was used as a sintering additive in the consolidation of the SiC matrix. The characterization of the composites was investigated by means of SEM and three point bending tests. These composites showed a dense morphology of the matrix region, by the creation of a secondary phase. The composites reinforced with SiC chopped fibers possessed a flexural strength of about 400 MPa at room temperature. The flexural strength of the carbon nanotubes composites had a tendency to decrease with increased volume fraction of the reinforcing material.

  1. SiC-SiC and C-SiC Honeycomb for Advanced Flight Structures, Phase II

    Data.gov (United States)

    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...

  2. Narrow photoluminescence peak from Ge(Si) islands embedded between tensile-strained Si layers

    Energy Technology Data Exchange (ETDEWEB)

    Shaleev, Mikhail; Novikov, Alexey; Baydakova, Nataliya; Yablonskiy, Artem; Drozdov, Yuriy; Lobanov, Dmitriy; Krasilnik, Zakhary [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Kuznetsov, Oleg [Physical-Technical Research Institute, Nizhny Novgorod State University, pr. Gagarina 23, 603950 Nizhny Novgorod (Russian Federation)

    2011-03-15

    The influence of thickness of the strained Si layers, measurement temperature and optical pumping power on width of the photoluminescence line from Ge(Si) self-assembled nanoislands grown on relaxed SiGe/Si(001) buffer layers and embedded between tensile-stained Si layers was studied. This line appears due to the II-type optical transition between the holes localized in islands and the electrons confined in tensile-strained Si layers under and above the islands. The possibility of tuning the photoluminescence line width by changing the strained Si layer thicknesses under and above the islands is showed. The decrease of the photoluminescence line width from Ge(Si) islands down to values comparable with width of the PL line from InAs/GaAs quantum dots was achieved due to the quantum confinement of electrons in thin strained Si layers and taking into account of the higher diffusion-induced smearing of strained Si layer above the islands. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Control of the graphene growth rate on capped SiC surface under strong Si confinement

    International Nuclear Information System (INIS)

    Çelebi, C.; Yanık, C.; Demirkol, A.G.; Kaya, İsmet İ.

    2013-01-01

    Highlights: ► Graphene is grown on capped SiC surface with well defined cavity size. ► Graphene growth rate linearly increases with the cavity height. ► Graphene uniformity is reduced with thickness. - Abstract: The effect of the degree of Si confinement on the thickness and morphology of UHV grown epitaxial graphene on (0 0 0 −1) SiC is investigated by using atomic force microscopy and Raman spectroscopy measurements. Prior to the graphene growth process, the C-face surface of a SiC substrate is capped by another SiC comprising three cavities on its Si-rich surface with depths varying from 0.5 to 2 microns. The Si atoms, thermally decomposed from the sample surface during high temperature annealing of the SiC cap /SiC sample stack, are separately trapped inside these individual cavities at the sample/cap interface. Our analyses show that the growth rate linearly increases with the cavity height. It was also found that stronger Si confinement yields more uniform graphene layers.

  4. The Degradation Behavior of SiCf/SiO2 Composites in High-Temperature Environment

    Science.gov (United States)

    Yang, Xiang; Cao, Feng; Qing, Wang; Peng, Zhi-hang; Wang, Yi

    2018-04-01

    SiCf/SiO2 composites had been fabricated efficiently by Sol-Gel method. The oxidation behavior, thermal shock property and ablation behavior of SiCf/SiO2 composites was investigated. SiCf/SiO2 composites showed higher oxidation resistance in oxidation atmosphere, the flexural strength retention ratio was larger than 90.00%. After 1300 °C thermal shock, the mass retention ratio was 97.00%, and the flexural strength retention ratio was 92.60%, while after 1500 °C thermal shock, the mass retention ratio was 95.37%, and the flexural strength retention ratio was 83.34%. After 15 s ablation, the mass loss rate was 0.049 g/s and recession loss rate was 0.067 mm/s. The SiO2 matrix was melted in priority and becomes loosen and porous. With the ablation going on, the oxides were washed away by the shearing action of the oxyacetylene flame. The evaporation of SiO2 took away large amount of heat, which is also beneficial to the protection for SiCf/SiO2 composites.

  5. Studies on Kondo insulating FeSi

    International Nuclear Information System (INIS)

    Bharathi, A.; Mani, Awadhesh; Ravindran, Nithya; Mathi Jaya, S.; Sundar, C.S.; Hariharan, Y.

    2000-01-01

    Temperature dependent electrical resistivity measurements have been carried out in Fe (1-x) Ru x Si and FeSi (1-x) Ge x to examine the robustness of the Kondo Insulating gap to substitution in the Fe and Si sublattices. The gap is seen to decrease with Ge substitution, while for Ru substitution the gap shows an initial decrease followed by an increase at higher concentration. The results can be understood in terms of the shift in the mobility edge due to disorder and/or pressure effects in combination with changes in band structure

  6. Properties of tribology for Si implanted PET

    International Nuclear Information System (INIS)

    Wu Yuguang; Zhang Tonghe; Zhang Xu; Liu Andong; Xie Mengxia; Zhang Aimin; Chen Jianmin

    2002-01-01

    Polyethylene terephthalate (PET) has been modified with Si ions from a metal vapor arc source (MEVVA). After implantation, the surface structure has been greatly changed. The experimental results of infrared absorption indicated that the particles are referred to rich carbon and SiC particles. The PET has been strengthened by these dispersed particles. The measurement results using nanometer hardness tester reveal that both surface hardness and modulus increase obviously. Therefore the surface wear resistance improved extremely. Finally the modification mechanism of Si implanted PET was discussed

  7. Implantation of P ions in SiO{sub 2} layers with embedded Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kachurin, G.A. E-mail: kachurin@isp.nsc.ru; Cherkova, S.G.; Volodin, V.A.; Kesler, V.G.; Gutakovsky, A.K.; Cherkov, A.G.; Bublikov, A.V.; Tetelbaum, D.I

    2004-08-01

    The effect of 10{sup 13}-10{sup 16} cm{sup -2} P ions implantation and of subsequent annealing on Si nanocrystals (Si-ncs), formed preliminarily in SiO{sub 2} layers by the ion-beam synthesis, has been studied. Photoluminescence (PL), Raman spectroscopy, high resolution electron microscopy (HREM), X-Ray Photoelectron Spectroscopy (XPS) and optical absorption were used for characterizations. The low fluence implantations have shown even individual displacements in Si-ncs quench their PL. Restoration of PL from partly damaged Si-ncs proceeds at annealing less than 1000 deg. C. In the low fluence implanted and annealed samples an increased Si-ncs PL has been found and ascribed to the radiation-induced shock crystallization of stressed Si nanoprecipitates. Annealing at temperatures under 1000 deg. C are inefficient when P ion fluences exceed 10{sup 14} cm{sup -2}, thus becoming capable to amorphize Si-ncs. High crystallization temperature of the amorphized Si-ncs is attributed to a counteraction of their shell layers. After implantation of the highest P fluences an enhanced recovery of PL was found from P concentration over 0.1 at.%. Raman spectroscopy and HREM showed an increased Si-ncs number in such layers. The effect resembles the impurity-enhanced crystallization, known for heavily doped bulk Si. This effect, along with the data obtained by XPS, is considered as an indication P atoms are really present inside the Si-ncs. However, no evidence of free electrons appearance has been observed. The fact is explained by an increased interaction of electrons with the donor nuclei in Si-ncs.

  8. Implantation of P ions in SiO2 layers with embedded Si nanocrystals

    International Nuclear Information System (INIS)

    Kachurin, G.A.; Cherkova, S.G.; Volodin, V.A.; Kesler, V.G.; Gutakovsky, A.K.; Cherkov, A.G.; Bublikov, A.V.; Tetelbaum, D.I.

    2004-01-01

    The effect of 10 13 -10 16 cm -2 P ions implantation and of subsequent annealing on Si nanocrystals (Si-ncs), formed preliminarily in SiO 2 layers by the ion-beam synthesis, has been studied. Photoluminescence (PL), Raman spectroscopy, high resolution electron microscopy (HREM), X-Ray Photoelectron Spectroscopy (XPS) and optical absorption were used for characterizations. The low fluence implantations have shown even individual displacements in Si-ncs quench their PL. Restoration of PL from partly damaged Si-ncs proceeds at annealing less than 1000 deg. C. In the low fluence implanted and annealed samples an increased Si-ncs PL has been found and ascribed to the radiation-induced shock crystallization of stressed Si nanoprecipitates. Annealing at temperatures under 1000 deg. C are inefficient when P ion fluences exceed 10 14 cm -2 , thus becoming capable to amorphize Si-ncs. High crystallization temperature of the amorphized Si-ncs is attributed to a counteraction of their shell layers. After implantation of the highest P fluences an enhanced recovery of PL was found from P concentration over 0.1 at.%. Raman spectroscopy and HREM showed an increased Si-ncs number in such layers. The effect resembles the impurity-enhanced crystallization, known for heavily doped bulk Si. This effect, along with the data obtained by XPS, is considered as an indication P atoms are really present inside the Si-ncs. However, no evidence of free electrons appearance has been observed. The fact is explained by an increased interaction of electrons with the donor nuclei in Si-ncs

  9. Reduced Pressure-Chemical Vapour Deposition of Si/SiGe heterostructures for nanoelectronics

    International Nuclear Information System (INIS)

    Hartmann, J.M.; Andrieu, F.; Lafond, D.; Ernst, T.; Bogumilowicz, Y.; Delaye, V.; Weber, O.; Rouchon, D.; Papon, A.M.; Cherkashin, N.

    2008-01-01

    We have first of all quantified the impact of pressure on Si and SiGe growth kinetics. Definite growth rate and Ge concentration increases with the pressure have been evidenced at low temperatures (650-750 deg. C). By contrast, the high temperature (950-1050 deg. C) Si growth rate either increases or decreases with pressure (gaseous precursor depending). We have then described the selective epitaxial growth process we use to form Si or Si 0.7 Ge 0.3 :B raised sources and drains on ultra-thin patterned Silicon-On-Insulator (SOI) substrates. We have afterwards presented the specifics of SiGe virtual substrates and of the tensile-strained Si layers grown on top (used as templates for the elaboration of tensily strained-SOI wafers). The tensile strain, which can be tailored from 1.3 up to 3 GPa, leads to an electron mobility gain by a factor of 2 in n-Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) built on top. High Ge content SiGe virtual substrates can also be used for the elaboration of compressively strained Ge channels, with impressive hole mobility gains (x9) compared to bulk Si. After that, we have described the main structural features of thick Ge layers grown directly on Si (that can be used as donor wafers for the elaboration of GeOI wafers or as the active medium of near infrared photo-detectors). Finally, we have shown how Si/SiGe multilayers can be used for the formation of high performance 3D devices such as multi-bridge channel or nano-beam gate-all-around FETs, the SiGe sacrificial layers being removed thanks to plasma dry etching, wet etching or in situ gaseous HCl etching

  10. Si cycling in a forest biogeosystem - the importance of transient state biogenic Si pools

    Science.gov (United States)

    Sommer, M.; Jochheim, H.; Höhn, A.; Breuer, J.; Zagorski, Z.; Busse, J.; Barkusky, D.; Meier, K.; Puppe, D.; Wanner, M.; Kaczorek, D.

    2013-07-01

    The relevance of biological Si cycling for dissolved silica (DSi) export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi) might contribute > 50% to DSi (Gerard et al., 2008). However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%). Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007-04/2011), we quantified (i) internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr) by BIOME-BGC (version ZALF), (ii) related Si budgets, and (iii) Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae). We quantified an average Si plant uptake of 35 kg Si ha-1 yr-1 - most of which is recycled to the soil by litterfall - and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha-1. The comparatively high DSi concentrations (6 mg L-1) and DSi exports (12 kg Si ha-1 yr-1) could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

  11. Si cycling in a forest biogeosystem – the importance of transient state biogenic Si pools

    Directory of Open Access Journals (Sweden)

    M. Sommer

    2013-07-01

    Full Text Available The relevance of biological Si cycling for dissolved silica (DSi export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi might contribute > 50% to DSi (Gerard et al., 2008. However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%. Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007–04/2011, we quantified (i internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr by BIOME-BGC (version ZALF, (ii related Si budgets, and (iii Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae. We quantified an average Si plant uptake of 35 kg Si ha−1 yr−1 – most of which is recycled to the soil by litterfall – and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha−1. The comparatively high DSi concentrations (6 mg L−1 and DSi exports (12 kg Si ha−1 yr−1 could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

  12. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo

    2018-02-28

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates. Then, bottom-contact graphene field effect transistors (G-FETs) were fabricated on the NP SiO2/Si substrate to measure the transfer curves. The graphene transferred onto the NP SiO2/Si substrate showed relatively n-doped behavior compared to the graphene transferred onto a flat SiO2/Si substrate, as evidenced by the blue-shift of the 2D peak position (∼2700 cm−1) in the Raman spectra due to contact doping. As the porosity increased within the substrate, the Dirac voltage shifted to a more positive or negative value, depending on the initial doping type (p- or n-type, respectively) of the contact doping. The Dirac voltage shifts with porosity were ascribed mainly to the compensation for the reduced capacitance owing to the SiO2–air hetero-structured dielectric layer within the periodically aligned nanopores capped by the suspended graphene (electrostatic doping). The hysteresis (Dirac voltage difference during the forward and backward scans) was reduced when utilizing an NP SiO2/Si substrate with smaller pores and/or a low porosity because fewer H2O or O2 molecules could be trapped inside the smaller pores.

  13. Chemical vapor deposition of Si/SiC nano-multilayer thin films

    International Nuclear Information System (INIS)

    Weber, A.; Remfort, R.; Woehrl, N.; Assenmacher, W.; Schulz, S.

    2015-01-01

    Stoichiometric SiC films were deposited with the commercially available single source precursor Et_3SiH by classical thermal chemical vapor deposition (CVD) as well as plasma-enhanced CVD at low temperatures in the absence of any other reactive gases. Temperature-variable deposition studies revealed that polycrystalline films containing different SiC polytypes with a Si to carbon ratio of close to 1:1 are formed at 1000 °C in thermal CVD process and below 100 °C in the plasma-enhanced CVD process. The plasma enhanced CVD process enables the reduction of residual stress in the deposited films and offers the deposition on temperature sensitive substrates in the future. In both deposition processes the film thickness can be controlled by variation of the process parameters such as the substrate temperature and the deposition time. The resulting material films were characterized with respect to their chemical composition and their crystallinity using scanning electron microscope, energy dispersive X-ray spectroscopy (XRD), atomic force microscopy, X-ray diffraction, grazing incidence X-ray diffraction, secondary ion mass spectrometry and Raman spectroscopy. Finally, Si/SiC multilayers of up to 10 individual layers of equal thickness (about 450 nm) were deposited at 1000 °C using Et_3SiH and SiH_4. The resulting multilayers features amorphous SiC films alternating with Si films, which feature larger crystals up to 300 nm size as measured by transmission electron microscopy as well as by XRD. XRD features three distinct peaks for Si(111), Si(220) and Si(311). - Highlights: • Stoichiometric silicon carbide films were deposited from a single source precursor. • Thermal as well as plasma-enhanced chemical vapor deposition was used. • Films morphology, crystallinity and chemical composition were characterized. • Silicon/silicon carbide multilayers of up to 10 individual nano-layers were deposited.

  14. Characterization of Si3N4-Al interface after corrosion tests Caracterização da interface Si3N4-Al após testes de corrosão

    Directory of Open Access Journals (Sweden)

    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

  15. Alpha-particle irradiation induced defects in SiO2 films of Si-SiO2 structures

    International Nuclear Information System (INIS)

    Koman, B.P.; Gal'chynskyy, O.V.; Kovalyuk, R.O.; Shkol'nyy, A.K.

    1996-01-01

    The aim of the work was to investigate alpha-particle irradiation induced defects in Si-SiO 2 structures by means of the thermostimulated discharge currents (TSDC) analysis. The object of investigation were (p-Si)-SiO 2 structures formed by a combined oxidation of the industrial p-Si wafers in dry and wet oxygen at temperature of 1150 C. The TSD currents were investigated in the temperature range between 90 and 500 K under linear heating rate. Pu 238 isotopes were the source of alpha-particles with an energy of 4-5 MeV and a density of 5.10 7 s -1 cm -2 . The TSD current curves show two peculiar maxima at about 370 and 480 K. Alpha-particle irradiation doesn't affect the general shape of the TSDC curves but leads to a shift of the maximum at 370 K and reduces the total electret charge which is accumulated in the Si-SiO 2 structures during polarization. The energy distribution function of the defects which are involved in SiO 2 polarization has been calculated. It showes that defects with activation energies of about 0.8 and 1.0 eV take part in forming the electret state, and these activation energies have certain energy distributions. It has been found that the TSDC maximum at 370 K has space charge nature and is caused by migration of hydrogen ions. In irradiated samples hydrogen and natrium ions localize on deeper trapping centres induced by alpha-particle irradiation. (orig.)

  16. C/SiC/MoSi2-Si multilayer coatings for carbon/carbon composites for protection against oxidation

    International Nuclear Information System (INIS)

    Zhang Yulei; Li Hejun; Qiang Xinfa; Li Kezhi; Zhang Shouyang

    2011-01-01

    Highlights: → A C/SiC/MoSi 2 -Si multilayer coating was prepared on C/C by slurry and pack cementation. → Multilayer coating can protect C/C for 300 h at 1873 K or 103 h at 1873 K in air. → The penetration cracks in the coating result in the weight loss of the coated C/C. → The fracture of the coated C/C in wind tunnel result from the excessive local stress. - Abstract: To improve the oxidation resistance of carbon/carbon (C/C) composites, a C/SiC/MoSi 2 -Si multilayer oxidation protective coating was prepared by slurry and pack cementation. The microstructure of the as-prepared coating was characterized by scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The isothermal oxidation and erosion resistance of the coating was investigated in electrical furnace and high temperature wind tunnel. The results showed that the multilayer coating could effectively protect C/C composites from oxidation in air for 300 h at 1773 K and 103 h at 1873 K, and the coated samples was fractured after erosion for 27 h at 1873 K h in wind tunnel. The weight loss of the coated specimens was considered to be caused by the formation of penetration cracks in the coating. The fracture of the coated C/C composites might result from the excessive local stress in the coating.

  17. Removal of C and SiC from Si and FeSi during ladle refining and solidification

    Energy Technology Data Exchange (ETDEWEB)

    Klevan, Ole Svein

    1997-12-31

    The utilization of solar energy by means of solar cells requires the Si to be very pure. The purity of Si is important for other applications as well. This thesis mainly studies the total removal of carbon from silicon and ferrosilicon. The decarburization includes removal of SiC particles by stirring and during casting in addition to reduction of dissolved carbon by gas purging. It was found that for three commercial qualities of FeSi75, Refined, Gransil, and Standard lumpy, the refined quality is lowest in carbon, followed by Gransil and Standard. A decarburization model was developed that shows the carbon removal by oxidation of dissolved carbon to be a slow process at atmospheric pressure. Gas stirring experiments have shown that silicon carbide particles are removed by transfer to the ladle wall. The casting method of ferrosilicon has a strong influence on the final total carbon content in the commercial alloy. Shipped refined FeSi contains about 100 ppm total carbon, while the molten alloy contains roughly 200 ppm. The total carbon out of the FeSi-furnace is about 1000 ppm. It is suggested that low values of carbon could be obtained on an industrial scale by injection of silica combined with the use of vacuum. Also, the casting system could be designed to give low carbon in part of the product. 122 refs., 50 figs., 24 tabs.

  18. Medidas de desempeño competitivo entre empresas con diferente estructura de la propiedad del capital

    Directory of Open Access Journals (Sweden)

    Josefina Fernández-Guadaño

    2013-01-01

    Full Text Available Este trabajo analiza la evolución del comportamiento económico comparado entre las empresas propiedad de sus trabajadores y las empresas capitalistas convencionales, con la finalidad, en función de los resultados, de potenciar el reconocimiento legal europeo del modelo de sociedad limitada laboral. Se trata de un estudio de corte exploratorio, la metodología utilizada para estudiar si existen diferencias entre los dos tipos de empresas ha sido la realización de pruebas paramétricas. Los resultados del análisis no evidencian de forma empírica los efectos positivos que se presuponían a las empresas propiedad de sus trabajadores, no siendo determinantes, por tanto, para hacer una recomendación regulatoria a nivel europeo, aunque encontrándose motivos suficientes para ampliar el estudio al análisis comparado de otros sujetos con regulación legal propia e, incluso, al análisis comparado de otras formas regulatorias existentes en otros Estados Miembros de la Unión Europea.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Relación entre el receptor de la favina y la galactosil uridil transferasa de la membrana de eritrocitos

    Directory of Open Access Journals (Sweden)

    María Inés Silva

    2010-07-01

    Full Text Available La extracción y purificación de un receptor de la favina fue realizada a partir de la membrana de eritrocitos, empleando para ello básicamente la cromatografía de intercambio iónico sobre DEAE-celulosa con miras a establecer su relación con la actividad de la Galactosa 1-fosfato Uridil Transferasa (EC 2.7.7.12, OUT. Se obtuvo una proteína con un alto grado de pureza (determinada por electroforesis sobre poliacrilamida en ausencia y presencia de SDS que presenta un peso molecular de 58.000 daltons y otra fracción que también interacttía con la favina y que contiene por lo menos seis proteínas de pesos moleculares entre 23.000 y 71.000 daltons. La fracción cromatográfica que contiene la proteína de 58.000 daltons presenta actividad de OUT, sin embargo esta actividad es inestable y se pierde después de mantener la muestra a 4'C durante 24 horas. De acuerdo a nuestros resultados, la dos actividades (receptor y actividad enzimática no interfieren entre si a pesar de encontrarse sobre la misma fracción proteica.

  2. Sentidos sobre a Amizade Entre Travestis: Construção de Repertórios Interpretativos

    Directory of Open Access Journals (Sweden)

    Rita Matins Godoy Rocha

    Full Text Available RESUMOConsiderando a necessidade de outros olhares sobre a complexidade do universo das travestis, este estudo objetiva descrever e analisar os repertórios interpretativos sobre as relações de amizade entre elas. Participaram 10 travestis do sudeste brasileiro. A entrevista individual semiestruturada foi o recurso metodológico escolhido, apoiada pelo caderno de campo. O estudo se baseou nas propostas de análise do discurso construcionista social. Cinco repertórios interpretativos sobre amizade foram identificados: Babado; Batalha; Família; Segredo e Uó. O uso dos repertórios, em diferentes arranjos, apresenta a maneira como as travestis contam sobre si, seja ressaltando seus potenciais, seja legitimando sentidos de marginalidade e estigma. Esses sentidos criam a possibilidade de existência entre elas e podem subsidiar a construção e implementação de intervenções e políticas direcionadas a essa população.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. Relação espacial entre a falange distal e o estojo córneo em éguas Campolinas jovens com e sem sinais de obesidade

    Directory of Open Access Journals (Sweden)

    Jéssica F. Magalhães

    Full Text Available RESUMO: Estudos prévios têm demonstrado alterações radiográficas em cascos de equinos obesos. Os objetivos foram estudar, com avaliação radiográfica, a relação espacial entre estojo córneo e falange distal de éguas jovens da raça Campolina com e sem obesidade. Foram utilizadas 22 éguas entre três e cinco anos de idade, sendo analisadas varáveis de adiposidade e medidas radiográficas dos cascos dos membros torácicos de éguas com escore corporal de 5 a 7/9 (Grupo Controle e de 8 a 9 (Grupo Obeso. Foram feitas comparações entre os grupos e correlacionaram-se as variáveis de adiposidade entre si, variáveis adiposidade com variáveis casco e variáveis de casco entre si. Utilizou-se o teste t de Student para variáveis paramétricas e o teste Mann-Whitney para as não-paramétricas, para as medidas de correlação, utilizou o teste de Pearson para duas amostras paramétricas e o teste de Spearman para comparações que envolvam pelo menos uma variável não paramétrica (P<0,05. Os resultados demonstraram que éguas Campolinas obesas, ainda jovens, já apresentam indícios de alteração na relação espacial entre estojo córneo e falange distal.

  5. Comportamiento a la corrosión electroquímica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyección térmica

    Directory of Open Access Journals (Sweden)

    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.

  6. RBS characterization of the deposition of very thin SiGe/SiO2 multilayers by LPCVD

    International Nuclear Information System (INIS)

    Munoz-Martin, A.; Climent-Font, A.; Rodriguez, A.; Sangrador, J.; Rodriguez, T.

    2005-01-01

    Multilayer structures consisting of several alternated layers of SiGe and SiO 2 with thickness ranging from 2 or Si as well as the deposition of SiO 2 on Si show negligible incubation times. The deposition of SiO 2 on SiGe, however, exhibits an incubation time of several minutes, which would be related to the oxidation of the surface necessary for the SiO 2 deposition to start. In all cases the film thickness increases linearly with deposition time, thus allowing the growth rates to be determined. These data allow the deposition process of these very thin layers to be accurately controlled

  7. Study of two-dimensional hole gas at Si/SiGe/Si inverted interface

    International Nuclear Information System (INIS)

    Sadeghazdeh, M.A.; Mironov, O.A.; Parry, C.P.; Philips, P.J.; Parker, E.H.C.; Wahll, T.E.; Emeleus, C.J.

    1998-01-01

    We have studied the transport of two-dimensional hole gas (2DHG) at the inverted interface of a strained Si 0.8 Ge 0.2 quantum well. By application of bias voltage to a Schottky gate on top of this inverted heterostructure the 2DHG density n s can be controlled, in the range of (1.5-5.2)x10 11 cm -2 . At temperature T = 033 K, the Hall mobility is 4650 cm 2 V -1 s -1 at the maximum carrier density. For lower sheet densities (n s 11 cm -2 ) the system undergoes a transition from a weak to strongly localised phase of significantly reduced mobility. From low temperature Shubnikov-de Haas oscillation measurements we have extracted the hole effective masses m* = (0.25 → 0.28)m o and the ratio of transport to quantum lifetimes α = (0.92 → 0.85) for the corresponding carrier density change of n s = (5.2 → 2.5)x10 11 cm -2 . These results can be explained in terms of the abnormal movement of the hole wave function towards the interface with decreasing n s , short range interface roughness scattering. (author)

  8. RELAÇÕES ENTRE ENSINO E APRENDIZAGEM NA EJA

    Directory of Open Access Journals (Sweden)

    José Moisés Nunes da Silva

    2010-01-01

    Full Text Available Este artigo tem por objetivo apresentar uma distinção clara e objetiva entre os processos de ensinar e aprender. Nessa perspectiva, primeiramente destaca a educação no contexto e como parte integrante dos processos de transformações do mundo contemporâneo. Em seguida, sustentado por diversos autores, discute-se a distinção entre ensinar e aprender. Espera-se contribuir para uma reflexão sobre a prática pedagógica docente e da necessidade de melhoria do processo de ensino e aprendizagem a fim de possibilitar uma educação em consonância com a concepção de formação integral do cidadão, à medida que tal distinção seja introjetada pelos professores. PALAVRAS-CHAVE: Ensinar. Aprender. Aprendizagem do jovem e do adulto.

  9. Afetividade entre professor e aluno no processo ensino-aprendizagem

    Directory of Open Access Journals (Sweden)

    Jéssica Simone Galdino Schaefer

    2015-06-01

    Full Text Available Este artigo tem como objetivo analisar as relações de afetividade entre professor e aluno no processo ensino-aprendizagem. Utiliza de metodologia com abordagem qualitativa, observação participante, e entrevistas semi-estruturadas. O lócus da pesquisa foi a Escola Municipal de Educação Básica Lizamara Aparecida Oliva de Almeida em Sinop, entre Fevereiro e Maio de 2014. Enquanto sujeitos, contou-se com professores e alunos do 3º ano do Ensino Fundamental. Dos resultados parciais, verificou-se que mesmo que a afetividade e a aprendizagem sejam reconhecidas teoricamente por Henri Wallon como elos fundamentais para o processo ensino-aprendizagem, ainda não é bem compreendido pelos sujeitos professores. Palavras-chave: psicologia educacional; afetividade; professores e alunos. 

  10. The Effect of Si Morphology on Machinability of Al-Si Alloys

    Directory of Open Access Journals (Sweden)

    Muhammet Uludağ

    2015-12-01

    Full Text Available Many of the cast parts require some sort of machining like milling, drilling to be used as a finished product. In order to improve the wear properties of Al alloys, Si is added. The solubility of Si in Al is quite low and it has a crystallite type structure. It behaves as particulate metal matrix composite which makes it an attractive element. Thus, the wear and machinability properties of these type of alloys depend on the morphology of Si in the matrix. In this work, Sr was added to alter the morphology of Si in Al-7Si and Al-12Si. Cylindrical shaped samples were cast and machinability characteristics of Sr addition was studied. The relationship between microstructure and machinability was evaluated.

  11. SiC/SiC fuel cladding R and D Project 'SCARLET': Status and future plan

    International Nuclear Information System (INIS)

    Kishimoto, Hirotatsu; Kohyama, Akira

    2015-01-01

    This paper provides the recent progress in SiC/SiC development towards early utilisation for LWRs based on NITE method. After the March 11 Disaster in East-Japan, ensuring safe technology for LWR became a top priority R and D in nuclear energy policy of Japan. Along this line, replacement of Zircaloy claddings with SiC/SiC based fuel cladding is becoming one of the most attractive options and a MEXT fund based project, SCARLET, and a METI fund based project have been launched as 5-year termed projects at Muroran Institute of Technology. These projects care for NITE process for making long SiC/SiC fuel pins and connecting technology integration. The SCARLET project also includes coolant compatibility and irradiation effect evaluations as LWR and LMFBR materials. The outline and the present status of the SCARLET project will be briefly introduced in the present paper. (authors)

  12. Si/SiC heterojunction optically controlled transistor with charge compensation layer

    Directory of Open Access Journals (Sweden)

    Pu Hongbin

    2016-01-01

    Full Text Available A novel n-SiC/p-Si/n-Si optically controlled transistor with charge compensation layer has been studied in the paper. The performance of the device is simulated using Silvaco Atlas tools, which indicates excellent performances of the device in both blocking state and conducting state. The device also has a good switching characteristic with 0.54μs as rising time and 0.66μs as falling time. With the charge compensation layer, the breakdown voltage and the spectral response intensity of the device are improved by 90V and 33A/W respectively. Compared with optically controlled transistor without charge compensation layer, the n-SiC/p-Si/n-Si optically controlled transistor with charge compensation layer has a better performance.

  13. Self-assembled epitaxial NiSi2 nanowires on Si(001) by reactive deposition epitaxy

    International Nuclear Information System (INIS)

    Chen, S.Y.; Chen, L.J.

    2006-01-01

    Self-assembled epitaxial NiSi 2 nanowires have been fabricated on Si(001) by reactive deposition epitaxy (RDE). The RDE method promoted nanowire growth since it provides deposited atoms sufficient kinetic energy for movement on the Si surface during the growth of silicide islands. The twin-related interface between NiSi 2 and Si is directly related to the nanowire formation since it breaks the symmetry of the surface and leads to the asymmetric growth. The temperature of RDE was found to greatly influence the formation of nanowires. By RDE at 750 deg. C, a high density of NiSi 2 nanowires was formed with an average aspect ratio of 30

  14. Structure and chemistry of passivated SiC/SiO{sub 2} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Houston Dycus, J.; Xu, Weizong; LeBeau, James M. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States); Lichtenwalner, Daniel J.; Hull, Brett; Palmour, John W. [Power Devices R& D, Wolfspeed, A Cree Company, Research Triangle Park, North Carolina 27709 (United States)

    2016-05-16

    Here, we report on the chemistry and structure of 4H-SiC/SiO{sub 2} interfaces passivated either by nitric oxide annealing or Ba deposition. Using aberration corrected scanning transmission electron microscopy and spectroscopy, we find that Ba and N remain localized at SiC/SiO{sub 2} interface after processing. Further, we find that the passivating species can introduce significant changes to the near-interface atomic structure of SiC. Specifically, we quantify significant strain for nitric oxide annealed sample where Si dangling bonds are capped by N. In contrast, strain is not observed at the interface of the Ba treated samples. Finally, we place these results in the context of field effect mobility.

  15. The structure modification of Si-SiO2 irradiated by Fe+ ion

    International Nuclear Information System (INIS)

    Jin Tao; Ma Zhongquan; Guo Qi

    1992-01-01

    The effect of the iron ion implantation on the oxide surface and SiO 2 -Si interface of MOS structure was studied by X-ray photo-electron spectroscopy (XPS), and the chemical states of compounds formed were examined. The results obtained show that in the surface layers of SiO 2 the pure Si micro-regions are formed under the implantation and the interface layers of SiO 2 the pure Si micro-regions are formed under the implantation and the interface thickness is almost doubled that leads to failure of MOS capacitors. The physical and chemical mechanisms of MOS structure change by Fe + ion implantation are also discussed and analyzed

  16. SiC Discrete Power Devices

    National Research Council Canada - National Science Library

    Baliga, B

    2000-01-01

    .... The investigation of the poor performance of the 4H-SiC ACCUFETs provided insights for changes in device design and process flow, for improving their breakdown voltage and specific on-resistance...

  17. Mass and QEC value of 26Si

    International Nuclear Information System (INIS)

    Eronen, T.; Elomaa, V.-V.; Hager, U.; Hakala, J.; Jokinen, A.; Kankainen, A.; Kessler, T.; Moore, I. D.; Rahaman, S.; Rissanen, J.; Weber, C.; Aeystoe, J.

    2009-01-01

    The Q EC value of the superallowed β emitter 26 Si has been measured with the JYFLTRAP Penning trap facility to be 4840.85(10) keV which is ten times more precise than any previous measurement. This leaves only the branching ratio to be improved before the Ft value of 26 Si can be used to test the conserved vector current hypothesis. As a consequence, the 25 Al(p,γ) 26 Si reaction Q-value (Q pγ ) was improved to be 5513.7(5) keV, limited now by the mass excess of 25 Al. The new Q pγ value changes the stellar production rate of 26 Si in nova ignition temperatures by about 10%

  18. Comparação do desempenho de duas bombas acopladas diretamente a geradores fotovoltaicos

    OpenAIRE

    Marco Antônio Steigleder

    2006-01-01

    No Brasil, assim como em outros países que recebem abundantes quantidades de radiação solar durante todo o ano, há um grande potencial para os sistemas que usam a tecnologia fotovoltaica para promover o bombeamento de água. Entretanto, a escolha dos conjuntos de motores e bombas mais adequados para cada situação passa pela análise do desempenho dos sistemas de bombeamento. Portanto, devem ser analisadas tanto as melhores configurações de geradores fotovoltaicos destinados a operar os conjunto...

  19. Estudo de arquiteturas de memória para máquinas MIMD fortemente acopladas

    OpenAIRE

    Carlos Eduardo Rodrigues Alves

    1993-01-01

    O uso de técnicas de processamento paralelo tem se tornado bastante comum na implementação de sistemas computacionais de alto desempenho. Uma destas técnicas, o uso de múltiplos processadores independentes ligados a um sistema de memória compartilhado(normalmente denominada paralelismo MIMD fortemente acoplado), tem sido pesquisado de maneira especial, devido a sua flexibilidade e facilidade de programação. No entanto, a implementação de sistemas de memória compartilhada apresenta d...

  20. Ternary alloying study of MoSi2

    International Nuclear Information System (INIS)

    Yi, D.; Li, C.; Akselsen, O.M.; Ulvensoen, J.H.

    1998-01-01

    Ternary alloying of MoSi 2 with adding a series of transition elements was investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Iron, Co, Ni, Cr, V, Ti, and Nb were chosen as alloying elements according to the AB 2 structure map or the atomic size factor. The studied MoSi 2 base alloys were prepared by the arc melting process from high-purity metals. The EDS analysis showed that Fe, Co, and Ni have no solid solubility in as-cast MoSi 2 , while Cr, V, Ti, and Nb exhibit limited solid solubilities, which were determined to be 1.4 ± 0.7, 1.4 ± 0.4, 0.4 ± 0.1, and 0.8 ± 0.1. Microstructural characterization indicated that Mo-Si-M VIII (M VIII = Fe, Co, Ni) and Mo-Si-Cr alloys have a two-phase as-cast microstructure, i.e., MoSi 2 matrix and the second-phase FeSi 2 , CoSi, NiSi 2 , and CrSi 2 , respectively. In as-cast Mo-Si-V, Mo-Si-Ti, and Mo-Si-Nb alloys, besides MoSi 2 and C40 phases, the third phases were observed, which have been identified to be (Mo, V) 5 Si 3 , TiSi 2 , and (Mo, Nb) 5 Si 3

  1. Si-Sb-Te materials for phase change memory applications

    International Nuclear Information System (INIS)

    Rao Feng; Song Zhitang; Ren Kun; Zhou Xilin; Cheng Yan; Wu Liangcai; Liu Bo

    2011-01-01

    Si-Sb-Te materials including Te-rich Si 2 Sb 2 Te 6 and Si x Sb 2 Te 3 with different Si contents have been systemically studied with the aim of finding the most suitable Si-Sb-Te composition for phase change random access memory (PCRAM) use. Si x Sb 2 Te 3 shows better thermal stability than Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 in that Si x Sb 2 Te 3 does not have serious Te separation under high annealing temperature. As Si content increases, the data retention ability of Si x Sb 2 Te 3 improves. The 10 years retention temperature for Si 3 Sb 2 Te 3 film is ∼ 393 K, which meets the long-term data storage requirements of automotive electronics. In addition, Si richer Si x Sb 2 Te 3 films also show improvement on thickness change upon annealing and adhesion on SiO 2 substrate compared to those of Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 films. However, the electrical performance of PCRAM cells based on Si x Sb 2 Te 3 films with x > 3.5 becomes worse in terms of stable and long-term operations. Si x Sb 2 Te 3 materials with 3 < x < 3.5 are proved to be suitable for PCRAM use to ensure good overall performance.

  2. Relações entre geografia e natureza

    Directory of Open Access Journals (Sweden)

    Jérome FOURNIER

    2001-12-01

    Full Text Available Este artigo aborda as relações entre geografia e natureza a partir dos seguintes tópicos: A geografia - uma ciência dos lugares e dos homens? Como definir a geografia física? A biogeografia e as relações com as disciplinas conexas. As contribuições da teoria da ecologia da paisagem. A paisagem deve ser estudada a partir de uma perspectiva sistêmica - geosistêmica, portanto interdisciplinar.

  3. Entre el erotismo y la pornografía

    Directory of Open Access Journals (Sweden)

    Edmundo Ribadeneira

    2015-01-01

    Full Text Available ¿Dónde termina el erotismo y comienza la pornografía? ¿Cuál el lugar de la obscenidad? Son algunas de las inquietudes que el autor aborda al tratar sobre estas tres expresiones de la sexualidad humana, que se ubican entre la indecencia más crasa y la imaginación artística, bastante atravesadas por la obscenidad de la política y el mercantilismo

  4. Association entre les hormones sexuelles, les marqueurs de ...

    African Journals Online (AJOL)

    Introduction: Le présent travail se propose d'étudier la relation entre les hormones sexuelles, notamment l'oestradiol et l'indice de l'oestradiol libre, le sulfate de déhydroépiandrosterone et la sex hormone binding globulin, les marqueurs de remodelage osseux et la densité minérale osseuse chez une population de ...

  5. Uso del profiláctico entre la juventud en sus relaciones de coito vaginal

    Directory of Open Access Journals (Sweden)

    Bimbela J.L.

    2002-01-01

    Full Text Available Objetivo: Describir el uso del profiláctico entre jóvenes en sus relaciones de coito vaginal e identificar los factores asociados a dicho uso. Método: La información se recogió mediante un cuestionario realizado en domicilio y con presencia del entrevistador, a 1.000 jóvenes (14-24 años residentes en Andalucía (España. Se llevó a cabo un análisis bifactorial y se ajustaron las ecuaciones de regresión logística jerárquica para verificar asociaciones entre la variable dependiente «uso del profiláctico en el coito vaginal» y las variables clasificadas por el modelo PRECEDE (predisponentes, facilitadores y reforzantes. El ajuste del modelo fue de un 38% según el estadístico de Nagelkerke. Resultados: 750 jóvenes mantuvieron relaciones afectivas y/o sexuales con contacto físico y un 63% de ellos practicó el coito vaginal (47% del total de la muestra. Los que tuvieron una sola relación de coito vaginal (12% del total de la muestra usaron profiláctico el 83% (un 10,3% del total de la muestra, y entre los que tuvieron más de una relación con coito vaginal (34% del total de la muestra, utilizaron siempre profiláctico un 49% (16,9% del total de la muestra. Las variables asociadas a su utilización siempre fueron dos: tener una intención de conducta «segura» con la pareja habitual y una baja frecuencia de la práctica. Las variables asociadas a no utilizarlo nunca fueron: estar emancipado, pensar que infectarse depende de factores externos (locus de control externo, identificar pocas zonas del cuerpo como sensibles al placer, pensar que no es necesario usar profiláctico si se confía en la pareja, tener una intención de conducta «insegura» con la pareja habitual y no hablar con la pareja sobre métodos preventivos antes de llevar a cabo la práctica sexual. Discusión: Los factores más asociados con el uso o no del profiláctico en el coito vaginal son predisponentes (actitudes, valores y creencias relacionados con el

  6. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia); Mitchell, I.V. [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1996-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  7. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T R [Australian National Univ., Canberra, ACT (Australia); Mitchell, I V [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1997-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  8. Silicon Photonics Cloud (SiCloud)

    DEFF Research Database (Denmark)

    DeVore, P. T. S.; Jiang, Y.; Lynch, M.

    2015-01-01

    Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

  9. La sauvegarde des grandes oeuvres de l'ingénierie du XXème siècle

    CERN Document Server

    Graf, Franz

    2016-01-01

    Consacré à la sauvegarde des grandes oeuvres de l’ingénierie du XXe siècle, ce premier numéro des Cahiers du TSAM explore le devenir de certaines des plus remarquables et emblématiques structures en béton du siècle passé. A travers les fi gures d’héroïques constructeurs, il interroge l’héritage construit des ingénieurs, convoquant les plus audacieux d’entre eux (Freyssinet, Isler, Maillart, Nervi, Vierendeel, etc.). Alors que la sauvegarde de l’architecture du XXe siècle s’est récemment constituée en discipline à part entière, la préservation des ouvrages de l’ingénierie de cette période est encore balbutiante. Considérés trop souvent sous le seul point de vue de la sécurité ou de la maintenance, ces ouvrages s’avèrent parfois de véritables chefs-d’oeuvre, jalons d’un «art de l’ingénieur» à la frontière entre performance technique et beauté plastique. Ces cahiers sont donc l’occasion d’initier, à l’appui d’exemples et de projets de sauvegarde con...

  10. Violencia contra mujeres embarazadas entre las usuarias del Instituto Mexicano del Seguro Social: un estudio sobre determinantes, prevalencia y severidad

    Directory of Open Access Journals (Sweden)

    Roberto Castro

    2002-01-01

    Full Text Available Se presentan los resultados de una encuesta entre 446 mujeres usuarias de los servicios de salud del Instituto Mexicano del Seguro Social (IMSS en Morelos, que se encontraban en su tercer trimestre de embarazo. El objetivo era indagar si la violencia contra mujeres se incrementa durante el embarazo o si, por el contrario, disminuye. Se encontró que la prevalencia no varió en ambos periodos (aproximadamente 15 por ciento, en general. En cambio, la severidad de la violencia emocional se incrementó durante el embarazo, mientras que la de la violencia física y sexual se mantuvo constante. Un análisis de regresión logística mostró que las variables que mejor predicen la violencia durante el embarazo son el número de hijos, el consumo de alcohol por parte de la pareja, la historia de violencia en la infancia de la pareja y la existencia de violencia durante el año previo al embarazo.

  11. La relación entre la inclusión financiera y el rezago social en México

    Directory of Open Access Journals (Sweden)

    José E. Calzada Rovirosa

    2015-06-01

    Full Text Available El objetivo del presente trabajo es analizar si en México existe relación entre la inclusión financiera y los indicadores de pobreza, con el fin de identificar si el acceso a los servicios financieros se relaciona con mejores condiciones de vida. Este tema es de relevancia para las políticas públicas, ya que el propósito de la reforma financiera promulgada en 2014 es contribuir al crecimiento económico incluyente. Para ello, se llevó a cabo un análisis utilizando la regresión lineal múltiple y el índice de correlación de Pearson, con los que se identificó que los rezagos de seguridad social tienen mayor relación con la inclusión financiera, particularmente con los puntos de acceso de corresponsales y los contratos de captación vía nómina. Asimismo, se encontró que las actividades de ahorro y crédito popular, aunque se dirigen a los sectores más vulnerables, no tienen relación con los indicadores de pobreza.

  12. Surface acoustic wave devices on AlN/3C–SiC/Si multilayer structures

    International Nuclear Information System (INIS)

    Lin, Chih-Ming; Lien, Wei-Cheng; Riekkinen, Tommi; Senesky, Debbie G; Pisano, Albert P; Chen, Yung-Yu; Felmetsger, Valery V

    2013-01-01

    Surface acoustic wave (SAW) propagation characteristics in a multilayer structure including a piezoelectric aluminum nitride (AlN) thin film and an epitaxial cubic silicon carbide (3C–SiC) layer on a silicon (Si) substrate are investigated by theoretical calculation in this work. Alternating current (ac) reactive magnetron sputtering was used to deposit highly c-axis-oriented AlN thin films, showing the full width at half maximum (FWHM) of the rocking curve of 1.36° on epitaxial 3C–SiC layers on Si substrates. In addition, conventional two-port SAW devices were fabricated on the AlN/3C–SiC/Si multilayer structure and SAW propagation properties in the multilayer structure were experimentally investigated. The surface wave in the AlN/3C–SiC/Si multilayer structure exhibits a phase velocity of 5528 m s −1 and an electromechanical coupling coefficient of 0.42%. The results demonstrate the potential of AlN thin films grown on epitaxial 3C–SiC layers to create layered SAW devices with higher phase velocities and larger electromechanical coupling coefficients than SAW devices on an AlN/Si multilayer structure. Moreover, the FWHM values of rocking curves of the AlN thin film and 3C–SiC layer remained constant after annealing for 500 h at 540 °C in air atmosphere. Accordingly, the layered SAW devices based on AlN thin films and 3C–SiC layers are applicable to timing and sensing applications in harsh environments. (paper)

  13. Si nanoparticle-decorated Si nanowire networks for Li-ion battery anodes

    KAUST Repository

    Hu, Liangbing

    2011-01-01

    We designed and fabricated binder-free, 3D porous silicon nanostructures for Li-ion battery anodes, where Si nanoparticles electrically contact current collectors via vertically grown silicon nanowires. When compared with a Si nanowire anode, the areal capacity was increased by a factor of 4 without having to use long, high temperature steps under vacuum that vapour-liquid-solid Si nanowire growth entails. © 2011 The Royal Society of Chemistry.

  14. Antioxidant migration resistance of SiOx layer in SiOx/PLA coated film.

    Science.gov (United States)

    Huang, Chongxing; Zhao, Yuan; Su, Hongxia; Bei, Ronghua

    2018-02-01

    As novel materials for food contact packaging, inorganic silicon oxide (SiO x ) films are high barrier property materials that have been developed rapidly and have attracted the attention of many manufacturers. For the safe use of SiO x films for food packaging it is vital to study the interaction between SiO x layers and food contaminants, as well as the function of a SiO x barrier layer in antioxidant migration resistance. In this study, we deposited a SiO x layer on polylactic acid (PLA)-based films to prepare SiO x /PLA coated films by plasma-enhanced chemical vapour deposition. Additionally, we compared PLA-based films and SiO x /PLA coated films in terms of the migration of different antioxidants (e.g. t-butylhydroquinone [TBHQ], butylated hydroxyanisole [BHA], and butylated hydroxytoluene [BHT]) via specific migration experiments and then investigated the effects of a SiO x layer on antioxidant migration under different conditions. The results indicate that antioxidant migration from SiO x /PLA coated films is similar to that for PLA-based films: with increase of temperature, decrease of food simulant polarity, and increase of single-sided contact time, the antioxidant migration rate and amount in SiO x /PLA coated films increase. The SiO x barrier layer significantly reduced the amount of migration of antioxidants with small and similar molecular weights and similar physical and chemical properties, while the degree of migration blocking was not significantly different among the studied antioxidants. However, the migration was affected by temperature and food simulant. Depending on the food simulants considered, the migration amount in SiO x /PLA coated films was reduced compared with that in PLA-based films by 42-46%, 44-47%, and 44-46% for TBHQ, BHA, and BHT, respectively.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Diálogo entre el islamismo y occidente

    Directory of Open Access Journals (Sweden)

    Ana María MARTÍN GÓMEZ

    2011-05-01

    Full Text Available Este artículo analiza uno de los fenómenos más actuales de nuestras sociedades pluralistas y multiculturales: el encuentro entre la civilización occidental y la islámica. La elaboración de esta nota crítica se ha llevado a cabo tras la lectura de tres libros fundamentales acerca de esta temática: Un paseo por el laberinto. Sobre política y religión en el diálogo entre civilizaciones, de José María García Gómez-Heras, Laicismo, agnosticismo y fundamentalismo de Antonio García-Santesmases, y El islamismo contra el Islam. Las claves para entender el terrorismo yihadista, de Gustavo de Arístegui. A partir de estos tres ensayos, se ha emprendido un estudio filosófico de la situación actual entre el islamismo y Occidente.

  17. Proyectos educativos: estudio comparativo entre Venezuela y Colombia

    Directory of Open Access Journals (Sweden)

    Mineira Finol

    2005-09-01

    Full Text Available El Proyecto Educativo Integral Comunitario (PEIC y el Proyecto Educativo Institucional constituyen la categoría de comparación entre Venezuela y Colombia; a tal fin, este estudio de tipo comparativo-documental se centró en determinar congruencias y discrepancias entre PEIC y PEI, utilizando el método comparativo estructurado en cuatro fases: descripción, interpretación, yuxtaposición y comparación, propuesto por Hilker y Bereday (1972 Entre los resultados se tienen: congruencias en cuanto surgen sobre las bases de diagnóstico externos efectuados por organismos internacionales UNESCO, CEPAL ante la inefectividad y baja productividad de ambos países; a nivel interno responden a políticas educativas reformadoras de currículum y leyes,. Discrepancias referidas al tiempo de implementación; en Venezuela a partir de 1996; Colombia en 1992; este último, consolidó las bases para la participación a través del gobierno escolar y de un sistema de evaluación institucional, muy incipiente en Venezuela.

  18. SiPM properties at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Biroth, Maik; Achenbach, Patrick; Thomas, Andreas [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, Mainz (Germany); Downie, Evangeline [George Washington University, DC (United States); Collaboration: A2-Collaboration

    2015-07-01

    At the electron accelerator Mainzer Mikrotron (MAMI) an active target build of polarizable scintillators will be operated at approximately 25 mK. To read out the scintillation light, the photodetectors have to withstand cryogenic temperatures of 4 K and high count rates. Therefore the properties of different types of silicon photomultipliers (SiPMs) were studied at cryogenic temperatures. In liquid nitrogen at 77 K, problems with quenching in Hamamatsu SiPMs and with the protective epoxy layer covering Zecotek SiPMs were observed. Tests with one Zecotek SiPM were successful after removal of the epoxy layer in liquid helium at 4 K and no after-pulses could be observed. Fundamental parameters like break-down voltage, single-pixel gain, crosstalk probability and the dark-count rate were measured and compared to room temperature. The photon detection efficiency was estimated by SiPMs response to short LED pulses. All these parameters were extracted by curve-fitting of SiPM charge spectra with a new analytical function.

  19. Separation of stress-free AlN/SiC thin films from Si substrate

    International Nuclear Information System (INIS)

    Redkov, A V; Osipov, A V; Mukhin, I S; Kukushkin, S A

    2016-01-01

    We separated AlN/SiC film from Si substrate by chemical etching of the AlN/SiC/Si heterostructure. The film fully repeats the size and geometry of the original sample and separated without destroying. It is demonstrated that a buffer layer of silicon carbide grown by a method of substitution of atoms may have an extensive hollow subsurface structure, which makes it easier to overcome the differences in the coefficients of thermal expansion during the growth of thin films. It is shown that after the separation of the film from the silicon substrate, mechanical stresses therein are almost absent. (paper)

  20. Transformation of point defects under annealing of neutron-irradiated Si and Si:Ge

    International Nuclear Information System (INIS)

    Pomozov, Yu.V.; Khirunenko, L.I.; Shakhovtsev, V.I.; Yashnik, V.I.

    1990-01-01

    Transformation of point radiation defects under isochronous annealing of neurton-irradaited Si and Si:Ge is studied. It is determined, that occurence of several new centers which produce A-centre range absorption bands is observed at annealing within 423-493 K temperature range. It is shown that vacancy and oxygen are included in the centers composition. It is found that VO centre transformation into VO 2 at annealing occurs via intermediate stage in contrast to that occuring in electron-irradiated crystals via VO direct diffusion to interstitial oxygen. Transformation of centers under Si ansd Si:Ge annealing occurs similarly

  1. Stability of Ta-encapsulating Si clusters on Si(111)-(7x7) surfaces

    CERN Document Server

    Uchida, N; Miyazaki, T; Kanayama, T

    2003-01-01

    Tantalum containing Si cluster ions TaSi sub 1 sub 0 sub - sub 1 sub 3 H sub x sup + were synthesized in an ion trap and deposited onto Si(111)-(7x7) surfaces with a kinetic energy of 18 eV. Scanning tunnelling microscope observations revealed that the clusters adsorbed on the surface without decomposition, consistent with ab initio calculation results, that predicted the clusters would have stable Si-cage structures with a Ta atom at the centre. (rapid communication)

  2. Vertical epitaxial wire-on-wire growth of Ge/Si on Si(100) substrate.

    Science.gov (United States)

    Shimizu, Tomohiro; Zhang, Zhang; Shingubara, Shoso; Senz, Stephan; Gösele, Ulrich

    2009-04-01

    Vertically aligned epitaxial Ge/Si heterostructure nanowire arrays on Si(100) substrates were prepared by a two-step chemical vapor deposition method in anodic aluminum oxide templates. n-Butylgermane vapor was employed as new safer precursor for Ge nanowire growth instead of germane. First a Si nanowire was grown by the vapor liquid solid growth mechanism using Au as catalyst and silane. The second step was the growth of Ge nanowires on top of the Si nanowires. The method presented will allow preparing epitaxially grown vertical heterostructure nanowires consisting of multiple materials on an arbitrary substrate avoiding undesired lateral growth.

  3. Next Generation, Si-Compatible Materials and Devices in the Si-Ge-Sn System

    Science.gov (United States)

    2015-10-09

    and conclusions The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8...Abstract The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8, SnD4. The...AFRL-AFOSR-VA-TR-2016-0044 Next generation, Si -compatible materials and devices in the Si - Ge -Sn system John Kouvetakis ARIZONA STATE UNIVERSITY Final

  4. SiNx layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

    International Nuclear Information System (INIS)

    Cho, Yunae; Kim, Eunah; Gwon, Minji; Kim, Dong-Wook; Park, Hyeong-Ho; Kim, Joondong

    2015-01-01

    We compared nanopatterned Si solar cells with and without SiN x layers. The SiN x layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN x layer played a crucial role in the improved carrier collection of the nanostructured solar cells

  5. White photoluminescence from Si/SiO{sub 2} nanostructured film

    Energy Technology Data Exchange (ETDEWEB)

    Duong, P.H.; Ngan, N.T.T.; Tuan, C.A. [Institute of Materials Science, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Huy, P.T. [International Training Institute of Materials Science, Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Itoh, T. [Graduate School of Engineering Science, Osaka University, Toyonaka (Japan)

    2008-12-15

    We present in this work the results of PL measurement of Si-NC embedded in Si/SiO{sub 2} multilayer system. A very intense broad luminescence band was observed in the sample under illumination in vacuum by UV laser line. The PL intensity enhancement and quenching effect observed in different ambients can be attributed to the energy exchange from NC to MO. The storage of the annealed sample in vacuum for a long time drastically changed the PL properties of Si-NC. The origin of these phenomena will be discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Specimen size effect considerations for irradiation studies of SiC/SiC

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-10-01

    For characterization of the irradiation performance of SiC/SiC, limited available irradiation volume generally dictates that tests be conducted on a small number of relatively small specimens. Flexure testing of two groups of bars with different sizes cut from the same SiC/SiC plate suggested the following lower limits for flexure specimen number and size: Six samples at a minimum for each condition and a minimum bar size of 30 x 6.0 x 2.0 mm{sup 3}.

  7. Residual stresses and mechanical properties of Si3N4/SiC multilayered composites with different SiC layers

    International Nuclear Information System (INIS)

    Liua, S.; Lia, Y.; Chena, P.; Lia, W.; Gaoa, S.; Zhang, B.; Yeb, F.

    2017-01-01

    The effect of residual stresses on the strength, toughness and work of fracture of Si3N4/SiC multilayered composites with different SiC layers has been investigated. It may be an effective way to design and optimize the mechanical properties of Si3N4/SiC multilayered composites by controlling the properties of SiC layers. Si3N4/SiC multilayered composites with different SiC layers were fabricated by aqueous tape casting and pressureless sintering. Residual stresses were calculated by using ANSYS simulation, the maximum values of tensile and compressive stresses were 553.2MPa and −552.1MPa, respectively. Step-like fracture was observed from the fracture surfaces. Fraction of delamination layers increased with the residual stress, which can improve the reliability of the materials. Tensile residual stress was benefit to improving toughness and work of fracture, but the strength of the composites decreased. [es

  8. Marker experiments in growth studies of Ni2Si, Pd2Si, and CrSi2 formed both by thermal annealing and by ion mixing

    International Nuclear Information System (INIS)

    Hung, L.S.; Mayer, J.W.; Pai, C.S.; Lau, S.S.

    1985-01-01

    Inert markers (evaporated tungsten and silver) were used in growth studies of silicides formed both by thermal annealing and by ion mixing in the Ni/Si, Pd/Si, and Cr/Si systems. The markers were initially imbedded inside silicides and backscattering spectrometry was used to determine the marker displacement after different processing conditions. The results obtained in thermal annealing are quite consistent with that found in previous investigations. Ni is the dominant diffusing species in Ni 2 Si, while Si is the diffusing species in CrSi 2 . In Pd 2 Si, both Pd and Si are moving species with Pd the faster of the two. In contrast, in growth of silicides by ion irradiation Si is the faster diffusing species in all three systems

  9. Silicon electrodeposition from chloride-fluoride melts containing K2SiF6 and SiO2

    Directory of Open Access Journals (Sweden)

    Zhuk Sergey I.

    2017-01-01

    Full Text Available Silicon electrodeposition on glassy carbon from the KF-KCl-K2SiF6, KF-KCl-K2SiF6-KOH and KF-KCl-K2SiF6-SiO2 melts was studied by the cyclic voltammetry. Тhe electroreduction of Si(IV to metallic Si was observed as a single 4-electron wave under all considered conditions. The reactions of cathode reduction of silicon from fluoride and oxyfluoride complexes were suggested. It was shown that the process can be controlled by the preliminary transformation of SiO44- to SiF62- and SiOxFyz-. The influence of the current density on structure and morphology of silicon deposits obtained during galvanostatic electrolysis of the KF-KCl-K2SiF6-SiO2 melt was studied.

  10. MeV Si ion modifications on the thermoelectric generators from Si/Si + Ge superlattice nano-layered films

    Science.gov (United States)

    Budak, S.; Heidary, K.; Johnson, R. B.; Colon, T.; Muntele, C.; Ila, D.

    2014-08-01

    The performance of thermoelectric materials and devices is characterized by a dimensionless figure of merit, ZT = S2σT/K, where, S and σ denote, respectively, the Seebeck coefficient and electrical conductivity, T is the absolute temperature in Kelvin and K represents the thermal conductivity. The figure of merit may be improved by means of raising either S or σ or by lowering K. In our laboratory, we have fabricated and characterized the performance of a large variety of thermoelectric generators (TEG). Two TEG groups comprised of 50 and 100 alternating layers of Si/Si + Ge multi-nanolayered superlattice films have been fabricated and thoroughly characterized. Ion beam assisted deposition (IBAD) was utilized to assemble the alternating sandwiched layers, resulting in total thickness of 300 nm and 317 nm for 50 and 100 layer devices, respectively. Rutherford Backscattering Spectroscopy (RBS) was employed in order to monitor the precise quantity of Si and Ge utilized in the construction of specific multilayer thin films. The material layers were subsequently impregnated with quantum dots and/or quantum clusters, in order to concurrently reduce the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and raise the cross plane electrical conductivity. The quantum dots/clusters were implanted via the 5 MeV Si ion bombardment which was performed using a Pelletron high energy ion beam accelerator. We have achieved remarkable results for the thermoelectric and optical properties of the Si/Si + Ge multilayer thin film TEG systems. We have demonstrated that with optimal setting of the 5 MeV Si ion beam bombardment fluences, one can fabricate TEG systems with figures of merits substantially higher than the values previously reported.

  11. MeV Si ion modifications on the thermoelectric generators from Si/Si + Ge superlattice nano-layered films

    Energy Technology Data Exchange (ETDEWEB)

    Budak, S., E-mail: satilmis.budak@aamu.edu [Department of Electrical Engineering and Computer Science, Alabama A and M University, Huntsville, AL (United States); Heidary, K. [Department of Electrical Engineering and Computer Science, Alabama A and M University, Huntsville, AL (United States); Johnson, R.B.; Colon, T. [Department of Physics, Alabama A and M University, Huntsville, AL (United States); Muntele, C. [Cygnus Scientific Services, Huntsville, AL (United States); Ila, D. [Department of Physics, Fayetteville St. University, Fayetteville, NC (United States)

    2014-08-15

    The performance of thermoelectric materials and devices is characterized by a dimensionless figure of merit, ZT = S{sup 2}σT/K, where, S and σ denote, respectively, the Seebeck coefficient and electrical conductivity, T is the absolute temperature in Kelvin and K represents the thermal conductivity. The figure of merit may be improved by means of raising either S or σ or by lowering K. In our laboratory, we have fabricated and characterized the performance of a large variety of thermoelectric generators (TEG). Two TEG groups comprised of 50 and 100 alternating layers of Si/Si + Ge multi-nanolayered superlattice films have been fabricated and thoroughly characterized. Ion beam assisted deposition (IBAD) was utilized to assemble the alternating sandwiched layers, resulting in total thickness of 300 nm and 317 nm for 50 and 100 layer devices, respectively. Rutherford Backscattering Spectroscopy (RBS) was employed in order to monitor the precise quantity of Si and Ge utilized in the construction of specific multilayer thin films. The material layers were subsequently impregnated with quantum dots and/or quantum clusters, in order to concurrently reduce the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and raise the cross plane electrical conductivity. The quantum dots/clusters were implanted via the 5 MeV Si ion bombardment which was performed using a Pelletron high energy ion beam accelerator. We have achieved remarkable results for the thermoelectric and optical properties of the Si/Si + Ge multilayer thin film TEG systems. We have demonstrated that with optimal setting of the 5 MeV Si ion beam bombardment fluences, one can fabricate TEG systems with figures of merits substantially higher than the values previously reported.

  12. Parrains et voisins? Espace et parrainage en banlieue parisienne au XIXe siècle

    Directory of Open Access Journals (Sweden)

    Vincent Gourdon

    2017-07-01

    Full Text Available Située à proximité de Paris, Aubervilliers, au cours du XIXe siècle, connaît une forte croissance de sa population et une transformation de son tissu social avec l’arrivée de migrants et l’orientation des activités économiques vers l’industrie au détriment de l’agriculture traditionnelle. Dans le cadre d’une réfl exion générale concernant la place du parrainage dans la construction des liens sociaux et particulièrement de la sociabilité communautaire à l’échelle locale, la distribution spatiale des parrains et marraines des enfants baptisés dans l’unique église paroissiale de la localité a été analysée sur trois siècles, afi n de montrer la fi n progressive du parrainage entre voisins appartenant à une même communauté, la paroisse, entre XVIIIe siècle et XIXe siècle, et l’élargissement du bassin de recrutement des parents spirituels, celui-ci témoignant du recul de l’esprit communautaire ancien. Au XIXe siècle, quand les choix dans la parenté n’amènent pas à aller quérir des parrains loin d’Aubervilliers, d’autres types de parrains voisins apparaissent: les gens du quartier, voire les voisins d’immeuble, prennent alors une place importante, notamment dans le quartier ouvrier peuplé de migrants de Quatre Chemins-Champ Blanc, au sud de la commune. Il ressort ainsi de l’analyse détaillée des baptêmes de 1881 que l’espace de la banlieue était loin d’être uniforme. Par beaucoup d’aspects dont le parrainage, Aubervilliers était bien une «périphérie» de Paris (cf. la proportion de parrains et marraines vivant dans la capitale, mais en son sein plusieurs quartiers, où des logiques de choix diff érentes étaient mises en oeuvre au moment des baptêmes, coexistaient.

  13. On the interplay between Si(110) epilayer atomic roughness and subsequent 3C-SiC growth direction

    Science.gov (United States)

    Khazaka, Rami; Michaud, Jean-François; Vennéguès, Philippe; Nguyen, Luan; Alquier, Daniel; Portail, Marc

    2016-11-01

    In this contribution, we performed the growth of a 3C-SiC/Si/3C-SiC layer stack on a Si(001) substrate by means of chemical vapor deposition. We show that, by tuning the growth conditions, the 3C-SiC epilayer can be grown along either the [111] direction or the [110] direction. The key parameter for the growth of the desired 3C-SiC orientation on the Si(110)/3C-SiC(001)/Si(001) heterostructure is highlighted and is linked to the Si epilayer surface morphology. The epitaxial relation between the layers has been identified using X-ray diffraction and transmission electron microscopy (TEM). We showed that, regardless of the top 3C-SiC epilayer orientation, domains rotated by 90° around the growth direction are present in the epilayer. Furthermore, the difference between the two 3C-SiC orientations was investigated by means of high magnification TEM. The results indicate that the faceted Si(110) epilayer surface morphology results in a (110)-oriented 3C-SiC epilayer, whereas a flat hetero-interface has been observed between 3C-SiC(111) and Si(110). The control of the top 3C-SiC growth direction can be advantageous for the development of new micro-electro-mechanical systems.

  14. PAPEL DE LA CONFIANZA en las relaciones entre organizaciones

    Directory of Open Access Journals (Sweden)

    Irene Juana Guillén Mondragón

    2006-07-01

    Full Text Available El objetivo del presente documento es analizar las definiciones y la importancia de la confianza para crear relaciones de cooperación entre organizaciones de naturaleza distinta. Se hace referencia a los modelos de organización dominantes para acercarnos a los nuevos mecanismos de regulación social propuestos por la sociología para tratar la organización, debido a que en el contexto actual las nuevas concepciones de la organización del trabajo han promovido en las organizaciones formas distintas de competir en el mercado. Procesos de cambio que obligan a las organizaciones a construir una nueva identidad y a renovar los contratos psicológicos con sus integrantes. La noción de confianza ha sido llevada del ámbito social al organizacional con la finalidad de lograr acuerdos entre organizaciones y al mismo tiempo lograr el compromiso de los integrantes de tales entidades. Para que estas puedan funcionar bajo este marco de transformaciones requieren de relaciones de colaboración regidas por la  confianza; relaciones que se dan en los niveles individual, dentro de la organización, entre organizaciones e institucionalmente. Los diferentes niveles de confianza están presentes en las relaciones que entablan los individuos, tanto dentro de la organización como en su entorno. Algunas de las reflexiones en torno a esta problemática nos llevan a pensar que el papel de la confianza es dinámico e incide en la transferencia y el intercambio de conocimientos, técnicas y procedimientos científicos, tecnologías, productos, capitales, entre otros. Además, las relaciones fundadas en la confianza requieren de la suspensión del propio interés, en beneficio de unaorientación colectiva (Mangematin y Thuderoz, 2003. Sin embargo, también se reconoce que con todo y la posibilidad que el hombre tiene de deliberar y de generar confianza, es evidente que entre los hombres prevalecen tanto la confianza calculada como los deseos de altruismo para entrar

  15. Revision of the Li13Si4 structure.

    Science.gov (United States)

    Zeilinger, Michael; Fässler, Thomas F

    2013-11-06

    Besides Li17Si4, Li16.42Si4, and Li15Si4, another lithium-rich representative in the Li-Si system is the phase Li13Si4 (trideca-lithium tetra-silicide), the structure of which has been determined previously [Frank et al. (1975 ▶). Z. Naturforsch. Teil B, 30, 10-13]. A careful analysis of X-ray diffraction patterns of Li13Si4 revealed discrepancies between experimentally observed and calculated Bragg positions. Therefore, we redetermined the structure of Li13Si4 on the basis of single-crystal X-ray diffraction data. Compared to the previous structure report, decisive differences are (i) the introduction of a split position for one Li site [occupancy ratio 0.838 (7):0.162 (7)], (ii) the anisotropic refinement of atomic displacement parameters for all atoms, and (iii) a high accuracy of atom positions and unit-cell parameters. The asymmetric unit of Li13Si4 contains two Si and seven Li atoms. Except for one Li atom situated on a site with symmetry 2/m, all other atoms are on mirror planes. The structure consists of isolated Si atoms as well as Si-Si dumbbells surrounded by Li atoms. Each Si atom is either 12- or 13-coordinated. The isolated Si atoms are situated in the ab plane at z = 0 and are strictly separated from the Si-Si dumbbells at z = 0.5.

  16. Electrospun a-Si using Liquid Silane/Polymer Inks

    Energy Technology Data Exchange (ETDEWEB)

    Doug Schulz

    2010-12-09

    Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  20. Entre-sons, entre-mundos, entre-idades: ações dialógicas, cultura adolescente e educação musical

    OpenAIRE

    Vertamatti, Leila Rosa Gonçalves [UNESP

    2012-01-01

    O presente trabalho tem como ponto central a reflexão a respeito da prática da Educação Musical de jovens entre 11 e 14 anos, do Colégio São José de São Bernardo do Campo, a partir de uma proposta que dialogue com o universo do adolescente, a invenção, a percepção do ambiente acústico, visual, social e cultural e o contexto escolar. A principal questão da investigação é a discussão de processos de elaboração de ações musicais com base em um conceito de prática que leve em conta a distância ex...

  1. Comparative study of SiC- and Si-based photovoltaic inverters

    Science.gov (United States)

    Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Shirahata, Yasuhiro; Ushijima, Kazufumi; Murozono, Mikio

    2017-01-01

    This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching frequency of 20 kHz. The power loss analysis also indicated a decreased loss of the DC-DC converter built with SiC Schottky barrier diodes led to the high efficiency for its increased switching frequency. These results clearly indicated feasibility of SiC devices even for sub-kW photovoltaic inverters, which will be available for the applications where compactness and efficiency are of tremendous importance.

  2. Mobility-limiting mechanisms in single and dual channel strained Si/SiGe MOSFETs

    International Nuclear Information System (INIS)

    Olsen, S.H.; Dobrosz, P.; Escobedo-Cousin, E.; Bull, S.J.; O'Neill, A.G.

    2005-01-01

    Dual channel strained Si/SiGe CMOS architectures currently receive great attention due to maximum performance benefits being predicted for both n- and p-channel MOSFETs. Epitaxial growth of a compressively strained SiGe layer followed by tensile strained Si can create a high mobility buried hole channel and a high mobility surface electron channel on a single relaxed SiGe virtual substrate. However, dual channel n-MOSFETs fabricated using a high thermal budget exhibit compromised mobility enhancements compared with single channel devices, in which both electron and hole channels form in strained Si. This paper investigates the mobility-limiting mechanisms of dual channel structures. The first evidence of increased interface roughness due to the introduction of compressively strained SiGe below the tensile strained Si channel is presented. Interface corrugations degrade electron mobility in the strained Si. Roughness measurements have been carried out using AFM and TEM. Filtering AFM images allowed roughness at wavelengths pertinent to carrier transport to be studied and the results are in agreement with electrical data. Furthermore, the first comparison of strain measurements in the surface channels of single and dual channel architectures is presented. Raman spectroscopy has been used to study channel strain both before and after processing and indicates that there is no impact of the buried SiGe layer on surface macrostrain. The results provide further evidence that the improved performance of the single channel devices fabricated using a high thermal budget arises from improved surface roughness and reduced Ge diffusion into the Si channel

  3. Si/C and H coadsorption at 4H-SiC{0001} surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wachowicz, E., E-mail: elwira@ifd.uni.wroc.pl [Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, PL-50-204 Wrocław (Poland); Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Pawińskiego 5a, PL-02-106 Warsaw (Poland)

    2016-06-15

    Highlights: • Si on C-terminated and C on Si-terminated surface adsorb in the H{sub 3} hollow site. • The preferred adsorption site is in contrary to the stacking order of bulk crystal. • The presence of hydrogen increases the adsorption energy of Si/C. • Hydrogen weakens the bonds between the adsorbed Si or C and the surface. • Carbon adsorbs on top of the surface carbon on the C-terminated surface. • With both C and H on Si-terminated surface the surface state vanishes. - Abstract: Density functional theory (DFT) study of adsorption of 0.25 monolayer of either Si or C on 4H-SiC{0001} surfaces is presented. The adsorption in high-symmetry sites on both Si- and C-terminated surfaces was examined and the influence of the preadsorbed 0.25 ML of hydrogen on the Si/C adsorption was considered. It was found out that for Si on C-terminated surface and C on Si-terminated the most favourable is threefolded adsorption site on both clean and H-precovered surface. This is contrary to the bulk crystal stacking order which would require adsorption on top of the topmost surface atom. In those cases, the presence of hydrogen weakens the bonding of the adsorbate. Carbon on the C-terminated surface, only binds on-top of the surface atom. The C−C bond-length is almost the same for the clean surface and for one with H and equals to ∼1.33 Å which is shorter by ∼0.2 than in diamond. The analysis of the electronic structure changes under adsorption is also presented.

  4. Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy.

    Science.gov (United States)

    Timpel, M; Wanderka, N; Schlesiger, R; Yamamoto, T; Isheim, D; Schmitz, G; Matsumura, S; Banhart, J

    2013-09-01

    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". Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Nietzsche entre Gide et Valéry

    OpenAIRE

    Large, Duncan

    2017-01-01

    Cette intervention a pour objet la réception et l’interprétation de Nietzsche chez deux auteurs qui dominaient la scène littéraire française dans la première moitié du XXe siècle: André Gide (1869-1951) et Paul Valéry (1871-1945). Ces deux écrivains exceptionnels – l’un, futur Prix Nobel, l’autre nominé pas moins de douze fois pour le même Prix et élu membre de l’Académie française – étaient au tournant du XXe siècle déjà des porte-étendards de l’avantgarde littéraire en France grâce à leurs ...

  6. siMS Score: Simple Method for Quantifying Metabolic Syndrome

    OpenAIRE

    Soldatovic, Ivan; Vukovic, Rade; Culafic, Djordje; Gajic, Milan; Dimitrijevic-Sreckovic, Vesna

    2016-01-01

    Objective To evaluate siMS score and siMS risk score, novel continuous metabolic syndrome scores as methods for quantification of metabolic status and risk. Materials and Methods Developed siMS score was calculated using formula: siMS score = 2*Waist/Height + Gly/5.6 + Tg/1.7 + TAsystolic/130?HDL/1.02 or 1.28 (for male or female subjects, respectively). siMS risk score was calculated using formula: siMS risk score = siMS score * age/45 or 50 (for male or female subjects, respectively) * famil...

  7. Ultrathin SiO{sub 2} layer formed by the nitric acid oxidation of Si (NAOS) method to improve the thermal-SiO{sub 2}/Si interface for crystalline Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Taketoshi; Nakajima, Hiroki; Irishika, Daichi; Nonaka, Takaaki; Imamura, Kentaro; Kobayashi, Hikaru, E-mail: h.kobayashi@sanken.osaka-u.ac.jp

    2017-02-15

    Highlights: • The density of interface states at the SiO{sub 2}/Si interface is decreased by NAOS. • The minority carrier lifetime is increased by the NAOS treatment. • Great interfacial properties of the NAOS layer are kept after thermal oxidation. - Abstract: A combination of the nitric acid oxidation of Si (NAOS) method and post-thermal oxidation is found to efficiently passivate the SiO{sub 2}/n-Si(100) interface. Thermal oxidation at 925 °C and annealing at 450 °C in pure hydrogen atmosphere increases the minority carrier lifetime by three orders of magnitude, and it is attributed to elimination of Si dangling bond interface states. Fabrication of an ultrathin, i.e., 1.1 nm, NAOS SiO{sub 2} layer before thermal oxidation and H{sub 2} annealing further increases the minority carrier lifetime by 30% from 8.6 to 11.1 ms, and decreased the interface state density by 10% from 6.9 × 10{sup 9} to 6.3 × 10{sup 9}eV{sup −1} cm{sup −2}. After thermal oxidation at 800 °C, the SiO{sub 2} layer on the NAOS-SiO{sub 2}/Si(100) structure is 2.26 nm thick, i.e., 0.24 nm thicker than that on the Si(100) surface, while after thermal oxidation at 925 °C, it is 4.2 nm thick, i.e., 0.4 nm thinner than that on Si(100). The chemical stability results from the higher atomic density of a NAOS SiO{sub 2} layer than that of a thermal oxide layer as reported in Ref. [28] (Asuha et al., 2002). Higher minority carrier lifetime in the presence of the NAOS layer indicates that the NAOS-SiO{sub 2}/Si interface with a low interface state density is preserved after thermal oxidation, which supports out-diffusion oxidation mechanism, by which a thermal oxide layer is formed on the NAOS SiO{sub 2} layer.

  8. Concordância entre citologia, colposcopia e histopatologia cervical Agreement between cytology, colposcopy and cervical histopathology

    Directory of Open Access Journals (Sweden)

    Letícia Maria Correia Katz

    2010-08-01

    Full Text Available OBJETIVO: avaliar a concordância da citologia convencional por Papanicolaou repetida no momento da colposcopia com os achados colposcópicos e a histopatologia. MÉTODOS: o estudo foi realizado no Laboratório Central de Saúde Pública do Estado de Pernambuco (LACEN, de janeiro a julho de 2008, em 397 mulheres com exame citopatológico alterado encaminhadas para avaliação colposcópica. No momento da colposcopia, repetiu-se a citologia em meio convencional, pesquisando-se os achados colposcópicos anormais. A nomenclatura citológica utilizada foi a de Bethesda e a histopatológica, da Organização Mundial de Saúde. A citologia no momento da colposcopia e a colposcopia foram comparadas entre si e com o resultado do histopatológico obtido por biópsia dirigida. A concordância entre os métodos foi avaliada pelo coeficiente Kappa (K, além do teste χ2 a um nível de significância de 5%. RESULTADOS: foi encontrada uma concordância fraca entre a citologia realizada no momento da colposcopia e a colposcopia, K=0,33 (IC95%=0,21-0,45 e entre a colposcopia e a histopatologia, K=0,35 (IC95%=0,39-0,51. Para a concordância entre citologia no momento da colposcopia e histopatologia, o Kappa foi de 0,41 (IC95%=0,29-0,530, considerado moderado. CONCLUSÕES: houve melhor concordância entre citologia e histopatologia do que entre colposcopia e citologia ou colposcopia e histopatologia.PURPOSE: to evaluate the agreement between conventional cytology using the Papanicolaou test, repeated at the time of colposcopy, with colposcopic and histopathological findings. METHODS: the study was carried out at the central public health laboratory of the state of Pernambuco between January and July, 2008, involving 397 women referred for colposcopic evaluation following an abnormal cervical smear test. Cytology was repeated at the time of colposcopy using conventional method, with particular attention being paid to the presence of abnormal colposcopic findings

  9. Near-surface segregation in irradiated Ni3Si

    International Nuclear Information System (INIS)

    Wagner, W.; Rehn, L.E.; Wiedersich, H.

    1982-01-01

    The radiation-induced growth of Ni 3 Si films on the surfaces of Ni(Si) alloys containing = 3 Si phase has been observed. Post-irradiation depth profiling by Auger electron spectroscopy, as well as in situ analysis by high-resolution Rutherford backscattering spectrometry, reveals Si-enrichment at the surfaces of Ni(Si) alloys in excess of stoichiometric Ni 3 Si during irradiation. Thin, near-surface layers with silicon concentrations of 28 to 30 at.% are observed, and even higher Si enrichment is found in the first few atom layers. Transmission electron microscopy and selected area-electron diffraction were employed to characterize these Si-enriched layers. A complex, multiple-spot diffraction pattern is observed superposed on the diffraction pattern of ordered Ni 3 Si. The d-spacings obtained from the extra spots are consistent with those of the orthohexagonal intermetallic compound Ni 5 Si 2 . (author)

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

    Directory of Open Access Journals (Sweden)

    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

  11. La Evolución de la RSC en Brasil entre las empresas cotizadas en Bovespa

    Directory of Open Access Journals (Sweden)

    Ana Gisbert

    2012-01-01

    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 mues - tra analizada está compuesta por 48 compañías cotizadas. En el análisis empírico se ha analizado el conte - nido 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 en 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 responsabilidad social corporativa debido a la ausencia de uniformidad. Asimismo, se observa que las empresas invierten en proyectos que en la mayor parte de los casos están muy relacionados con la actividad principal que desar - rollan. 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 consi - derable. La inversión medioambiental es la que se ha mantenido, debido especialmente a una significativa reducción en el sector petrolífero

  12. Traducción automatizada de programas entre lenguajes de operaciones

    Directory of Open Access Journals (Sweden)

    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

  13. Gate-stack engineering for self-organized Ge-dot/SiO2/SiGe-shell MOS capacitors

    Directory of Open Access Journals (Sweden)

    Wei-Ting eLai

    2016-02-01

    Full Text Available We report the first-of-its-kind, self-organized gate-stack heterostructure of Ge-dot/SiO2/SiGe-shell on Si fabricated in a single step through the selective oxidation of a SiGe nano-patterned pillar over a Si3N4 buffer layer on a Si substrate. Process-controlled tunability of the Ge-dot size (7.5−90 nm, the SiO2 thickness (3−4 nm, and as well the SiGe-shell thickness (2−15 nm has been demonstrated, enabling a practically-achievable core building block for Ge-based metal-oxide-semiconductor (MOS devices. Detailed morphologies, structural, and electrical interfacial properties of the SiO2/Ge-dot and SiO2/SiGe interfaces were assessed using transmission electron microscopy, energy dispersive x-ray spectroscopy, and temperature-dependent high/low-frequency capacitance-voltage measurements. Notably, NiGe/SiO2/SiGe and Al/SiO2/Ge-dot/SiO2/SiGe MOS capacitors exhibit low interface trap densities of as low as 3-5x10^11 cm^-2·eV^-1 and fixed charge densities of 1-5x10^11 cm^-2, suggesting good-quality SiO2/SiGe-shell and SiO2/Ge-dot interfaces. In addition, the advantage of having single-crystalline Si1-xGex shell (x > 0.5 in a compressive stress state in our self-aligned gate-stack heterostructure has great promise for possible SiGe (or Ge MOS nanoelectronic and nanophotonic applications.

  14. Metallization of ion beam synthesized Si/3C-SiC/Si layer systems by high-dose implantation of transition metal ions

    International Nuclear Information System (INIS)

    Lindner, J.K.N.; Wenzel, S.; Stritzker, B.

    2001-01-01

    The formation of metal silicide layers contacting an ion beam synthesized buried 3C-SiC layer in silicon by means of high-dose titanium and molybdenum implantations is reported. Two different strategies to form such contact layers are explored. The titanium implantation aims to convert the Si top layer of an epitaxial Si/SiC/Si layer sequence into TiSi 2 , while Mo implantations were performed directly into the SiC layer after selectively etching off all capping layers. Textured and high-temperature stable C54-TiSi 2 layers with small additions of more metal-rich silicides are obtained in the case of the Ti implantations. Mo implantations result in the formation of the high-temperature phase β-MoSi 2 , which also grows textured on the substrate. The formation of cavities in the silicon substrate at the lower SiC/Si interface due to the Si consumption by the growing silicide phase is observed in both cases. It probably constitutes a problem, occurring whenever thin SiC films on silicon have to be contacted by silicide forming metals independent of the deposition technique used. It is shown that this problem can be solved with ion beam synthesized contact layers by proper adjustment of the metal ion dose

  15. Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

    International Nuclear Information System (INIS)

    Suvorova, N.A.; Lopez, C.M.; Irene, E.A.; Suvorova, A.A.; Saunders, M.

    2004-01-01

    (Ba,Sr)TiO 3 (BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO 2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO 2 on Si or 3.5 nm SiO 2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO 2 . Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density D it of an order of magnitude for oxidized Si substrates with a thicker SiO 2 underlayer. Further reduction of D it was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization

  16. Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

    Science.gov (United States)

    Suvorova, N. A.; Lopez, C. M.; Irene, E. A.; Suvorova, A. A.; Saunders, M.

    2004-03-01

    (Ba,Sr)TiO3(BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO2 on Si or 3.5 nm SiO2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO2. Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density Dit of an order of magnitude for oxidized Si substrates with a thicker SiO2 underlayer. Further reduction of Dit was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization.

  17. Exceptional cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si heterostructures

    Science.gov (United States)

    Chen, Da; Wang, Dadi; Chang, Yongwei; Li, Ya; Ding, Rui; Li, Jiurong; Chen, Xiao; Wang, Gang; Guo, Qinglei

    2018-01-01

    The cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si structures after thermal annealing was investigated. The crack formation position is found to closely correlate with the thickness of the buried Si0.70Ge0.30 layer. For H-implanted Si containing a buried 3-nm-thick B-doped Si0.70Ge0.30 layer, localized continuous cracking occurs at the interfaces on both sides of the Si0.70Ge0.30 interlayer. Once the thickness of the buried Si0.70Ge0.30 layer increases to 15 and 70 nm, however, a continuous sharp crack is individually observed along the interface between the Si substrate and the B-doped Si0.70Ge0.30 interlayer. We attribute this exceptional cracking behavior to the existence of shear stress on both sides of the buried Si0.70Ge0.30 layer and the subsequent trapping of hydrogen, which leads to a crack in a well-controlled manner. This work may pave the way for high-quality Si or SiGe membrane transfer in a feasible manner, thus expediting its potential applications to ultrathin silicon-on-insulator (SOI) or silicon-germanium-on-insulator (SGOI) production.

  18. Transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si1-xCx nanocomposites mixed with Si nanoparticles and C atoms

    International Nuclear Information System (INIS)

    Shin, J.W.; Oh, D.H.; Kim, T.W.; Cho, W.J.

    2009-01-01

    Bright-field transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images, and fast-Fourier transformed electron-diffraction patterns showed that n-butyl terminated Si nanoparticles were aggregated. The formation of Si 1-x C x nanocomposites was mixed with Si nanoparticles and C atoms embedded in a SiO 2 layer due to the diffusion of C atoms from n-butyl termination shells into aggregated Si nanoparticles. Atomic force microscopy (AFM) images showed that the Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms existed in almost all regions of the SiO 2 layer. The formation mechanism of Si nanoparticles and the transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms are described on the basis of the TEM, HRTEM, and AFM results. These results can help to improve the understanding of the formation mechanism of Si nanoparticles.

  19. A paixão pela imagem: o eu como cenógrafo das virtualidades do si mesmo

    Directory of Open Access Journals (Sweden)

    Marina Pinheiro

    2016-03-01

    Full Text Available É propósito do presente trabalho perscrutar, através das expressões culturais da virtualização do si mesmo, a equivocidade pendular entre o fetichismo comum e as formas de estetização do desejo na atualidade tecnológica. Desde a primeira formação egoica, “projeção de superfície” do olhar materno, ao ego virtualizado nas marcações corporais extremas, ou mesmo avatarizado nos games e redes sociais; torna-se necessário à psicanálise a discussão sobre a dialética entre objetificação e possibilidades de autoração simbólica da existência na contemporaneidade.

  20. Si/SiGe heterointerfaces in one-, two-, and three-dimensional nanostructures: their impact on SiGe light emission

    Science.gov (United States)

    Lockwood, David; Wu, Xiaohua; Baribeau, Jean-Marc; Mala, Selina; Wang, Xialou; Tsybeskov, Leonid

    2016-03-01

    Fast optical interconnects together with an associated light emitter that are both compatible with conventional Si-based complementary metal-oxide- semiconductor (CMOS) integrated circuit technology is an unavoidable requirement for the next-generation microprocessors and computers. Self-assembled Si/Si1-xGex nanostructures, which can emit light at wavelengths within the important optical communication wavelength range of 1.3 - 1.55 μm, are already compatible with standard CMOS practices. However, the expected long carrier radiative lifetimes observed to date in Si and Si/Si1-xGex nanostructures have prevented the attainment of efficient light-emitting devices including the desired lasers. Thus, the engineering of Si/Si1-xGex heterostructures having a controlled composition and sharp interfaces is crucial for producing the requisite fast and efficient photoluminescence (PL) at energies in the range 0.8-0.9 eV. In this paper we assess how the nature of the interfaces between SiGe nanostructures and Si in heterostructures strongly affects carrier mobility and recombination for physical confinement in three dimensions (corresponding to the case of quantum dots), two dimensions (corresponding to quantum wires), and one dimension (corresponding to quantum wells). The interface sharpness is influenced by many factors such as growth conditions, strain, and thermal processing, which in practice can make it difficult to attain the ideal structures required. This is certainly the case for nanostructure confinement in one dimension. However, we demonstrate that axial Si/Ge nanowire (NW) heterojunctions (HJs) with a Si/Ge NW diameter in the range 50 - 120 nm produce a clear PL signal associated with band-to-band electron-hole recombination at the NW HJ that is attributed to a specific interfacial SiGe alloy composition. For three-dimensional confinement, the experiments outlined here show that two quite different Si1-xGex nanostructures incorporated into a Si0.6Ge0.4 wavy