WorldWideScience

Sample records for alta densidade hdpe

  1. Characterization of composite high density polyethylene and layered zirconium phosphate; Caracterizacao de composito de polietileno de alta densidade (HDPE) e fosfato de zirconio lamelar

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Zirconium phosphate (ZrP) (2 w%), synthesized by direct precipitation method, was used in the preparation of composite with high density polyethylene (HDPE), through extrusion processing in the molten state. Wide angle x-ray diffraction (WAXD), stress-strain mechanical analysis and scanning electron microscopy (SEM) techniques were used for ZrP, neat polymer and composite mechanical and morphologic characterization. Although there was a slight increase in the Young modulus, WAXD and SEM analysis showed that the intercalation of the HDPE matrix in the filler galleries did not occur, probably due to the insufficient lamellae spacing to intercalate the polymer chains. Then, a microcomposite was achieved. (author)

  2. Morfología y propiedades de politereftalato de etilen-glicol y polietileno de alta densidad

    OpenAIRE

    Guerrero, Carlos; Lozano, Tomás; González, Virgilio; Arroyo, Eliud

    2003-01-01

    Se estudiaron mezclas de politereftalato de etilen- glicol, PET y polietileno de alta densidad, HDPE, con y sin agente compatibilizante. Ambos materiales se usan ampliamente en la industria de bebidas carbonatadas. El agente compatibilizante que se usó fue un copolímero de etileno y ácido metacrílico parcialmente neutralizado con zinc (Surlyn). Como hipótesis se planteó que el segmento olefínico del Surlyn podría ser compatible con el HDPE, mientras que los grupos c...

  3. Síntesis y caracterización de un material compuesto a base de polietileno de alta densidad y magnetita pulverizada

    OpenAIRE

    Garzón Posada, Andrés Orlando

    2015-01-01

    En este trabajo se pretende producir un material compuesto a base de polietileno de alta densidad (HDPE) y magnetita pulverizada (Fe3O4) con el fin de caracterizar sus propiedades mecánicas, magnéticas y eléctricas. Este tipo de matrices poliméricas reforzadas con magnetita han sido motivo de estudio en los recientes años con el fin de desarrollar materiales con aplicaciones tecnológicas enfocadas a la ingeniería y a la biomedicina. Para optimizar el enfoque y el uso tanto de este material co...

  4. Sistemas de producción de fresa de altas densidades.

    OpenAIRE

    Ramírez Gómez, Humberto

    2011-01-01

    En México se produce fresa con alta tecnología pero existe escasa investigación sobre la productividad de la fresa en sistemas hidropónicos con altas densidades. El presente estudio se realizó con la finalidad de evaluar la fisiología, rendimiento, calidad y rentabilidad de la fresa de altas densidades en cuatro sistemas hidropónicos. Los tratamientos estudiados fueron: bolsas individuales (BI), vertical con tres tubos (V3T), vertical con cuatro tubos (V4T) y vertical con macetas hidropónicas...

  5. Cultivo de cachama blanca en altas densidades y en dos sistemas cerrados

    Directory of Open Access Journals (Sweden)

    Germán Poleo

    2011-04-01

    Full Text Available El objetivo de este trabajo fue evaluar la tolerancia de la cachama blanca, Piaractus brachypomus, a cultivos en altas densidades en sistemas cerrados. Novecientos alevines de 44,3±26 g de peso, se distribuyeron en seis tanques de concreto, con 4,8 m³ de agua. Tres tanques presentaron cero recambio de agua (SCR, y en otros tres, el agua se hizo circular a través de un bioclarificador (SRA. Ambos tratamientos presentaron fuerte aireación para mantener los sólidos en suspensión y suministrar aire. Los peces se alimentaron a saciedad con pienso comercial por 192 días. Los parámetros de calidad de agua como: oxígeno disuelto, amonio total, nitritos, nitratos, alcalinidad, dureza, temperatura y pH, se midieron semanalmente. Los peces en el SCR crecieron a una tasa de 2,34±0,05 g por día, y tuvieron conversión alimenticia de 1,5±0,06, densidad final de 12,96±0,53 kg m-3, y peso final de 449,5±99 g. En el SRA, los peces crecieron 2,33±0,03 g por día, con conversión alimenticia de 1,6±0,07, densidad final de 12,13±1,12 kg m-3, y peso final de 446,5±10 g. La cachama blanca puede ser cultivada en sistemas cerrados con cero recambio de agua en altas densidades.

  6. Cultivo de cachama blanca en altas densidades y en dos sistemas cerrados

    OpenAIRE

    Germán Poleo; José Vicente Aranbarrio; Lismen Mendoza; Oneida Romero

    2011-01-01

    El objetivo de este trabajo fue evaluar la tolerancia de la cachama blanca, Piaractus brachypomus, a cultivos en altas densidades en sistemas cerrados. Novecientos alevines de 44,3±26 g de peso, se distribuyeron en seis tanques de concreto, con 4,8 m³ de agua. Tres tanques presentaron cero recambio de agua (SCR), y en otros tres, el agua se hizo circular a través de un bioclarificador (SRA). Ambos tratamientos presentaron fuerte aireación para mantener los sólidos en suspensión y suministrar ...

  7. Nanocompósitos de blendas HDPE/LLDPE e OMMT - Parte II: avaliação das propriedades térmica, óticas e de transporte a gases

    OpenAIRE

    Fabio R. Passador; Daniel R. Travain; Eduardo H. Backes; Adhemar C. Ruvolo Filho; Luiz A. Pessan

    2013-01-01

    Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados sob fusão em extrusora de dupla-rosca, utilizando HDPE-g-MA como agente compatibilizante. Os nanocompósitos foram caracterizados através das propriedades térmicas, óticas e de transporte de gases. A blenda HDPE/LLDPE e os nanocompósitos das blendas HDPE/LLDPE como esperado comportam-se como barreira ao vapor de água e são per...

  8. Reologia de polietileno de alta densidade tenacificado com polietileno elastomérico Rheology of high density polyethylene toughened with elastomeric polyethylene

    Directory of Open Access Journals (Sweden)

    Maria José O. C. Guimarães

    2003-06-01

    Full Text Available Neste trabalho foram estudadas as propriedades reológicas de polietileno de alta densidade (HDPE tenacificado com dois tipos de elastômeros metalocênicos à base de poli(etileno-co-octeno (EOC. Estes elastômeros são polímeros comerciais com diferenças quanto ao peso molecular, índice de fluidez e índice Dow de reologia (DRI. Misturas físicas de HDPE e EOC foram processadas em extrusora monorosca Wortex (L/D=32, à 230 °C e 50 rpm, utilizando percentagem mássica dos EOCs de 5% a 80%. As propriedades reológicas foram avaliadas em experimentos estacionários e dinâmicos a 190 °C e taxas de cisalhamento na faixa de 90 s-1 a 1500 s-1 e freqüências na faixa de 10-1 rad/s a 10² rad/s. As misturas HDPE/EOC exibiram pseudoplasticidade e comportamento reológico complexo. A complexidade do comportamento reológico foi acentuada com o aumento do peso molecular e da concentração de ramificações de cadeia longa (DRI do EOC.In this work rheological properties of high density polyethylene toughened with two different grades of metallocene elastomers based on poly(ethylene-co-octene were studied. These elastomers were commercial polymers differing in molecular weight, and Dow Rheology Index (DRI. Blends were processed in a Wortex single screw extruder (L/D=32, at 230 °C and 50 rpm, using mass fractions of EOC in the range from 5% to 80%. The rheological properties were evaluated in steady and dynamic experiments at 190 °C and shear rates in the range from 90 s-1 to 1500 s-1 with frequencies from 10-1 s-1 to 10-2 s-1. The blends exhibited pseudoplasticity and complex rheological behavior. The complex rheological behavior was intensified with increasing molecular weight and long chain branching proportion (DRI in the EOC elastomers.

  9. Efecto de la temperatura en la densidad de la leche entera bajo alta presión

    OpenAIRE

    Guignon, Bérengère; Rey I.; Sanz Martínez, Pedro D.

    2012-01-01

    El procesado con alta presión se está convirtiendo en una eficaz tecnología de conservación. Con ella, se prolonga la vida útil de los alimentos, manteniendo sus cualidades. Para controlar y optimizar la uniformidad de los tratamientos, cada vez se emplea más, la modelización matemática. La realización de los correspondientes cálculos, requieren disponer de las propiedades físicas de los alimentos. Entre ellas está la densidad. Ante la carencia de estos datos, se ha llevad...

  10. Polietileno de Alta Densidade Tenacificado com Elastômero Metalocênico: 1. Propriedades Mecânicas e Características Morfológicas Rubber Toughened High Density Polyethylene: 1. Mechanical Properties and Morphological Characteristics

    Directory of Open Access Journals (Sweden)

    Maria José O. C. Guimarães

    2002-01-01

    Full Text Available Neste trabalho foram estudadas as propriedades mecânicas e morfológicas de polietileno de alta densidade (HDPE tenacificado com dois tipos de elastômeros metalocênicos à base de etileno/1- octeno (EOC. Esses elastômeros são polímeros comerciais com diferenças quanto ao peso molecular, índice de fluidez e índice Dow de reologia (DRI. Misturas físicas de HDPE e EOC foram processadas em extrusora monorosca Wortex (L/D=32, à 230°C e 50 rpm, utilizando percentagem mássica do EOC de 5% a 80%. Foi observado um efeito sinergístico nas propriedades tênseis e características de supertenacificação para materiais contendo proporções do EOC maiores do que 5%. Cavitação, deformação plástica e cavitação fibrilada foram observados nos processos de deformação. Materiais contendo até 50% do EOC apresentaram morfologias dispersas com domínios elastoméricos esféricos, distribuídos uniformemente e com tamanho médio de partícula na faixa de 0,30 a 0,45 µm. A tenacificação de HDPE com os elastômeros etilênicos produziu materiais com boas propriedades e compatibilização tecnológica devido à existência de baixa tensão interfacial entre esses polímeros.The mechanical and morphological properties of high density polyethylene (HDPE toughened with two different grades of metallocene elastomers based on ethylene/1- octene (EOC were studied. These elastomers were commercial polymers differing in molecular weight, melt flow index and Dow rheology index (DRI. Blends were processed in a Wortex single screw extruder (L/D=32, at 230°C and 50 rpm, using mass fraction weight percent of EOC in the range from 5% to 80%. A synergistic effect on the tensile properties and supertough behavior for blends with EOC concentrations higher than 5% was observed. Cavitation, plastic deformation and fibrillized cavitation were observed in the deformation processes. Materials containing up to 50% of EOC exhibited dispersed morphologies with EOC

  11. Materiales de cambio de fase basados en mezclas de polietileno de alta densidad y cera

    OpenAIRE

    Utande Clemente, Rocío

    2013-01-01

    El objetivo de este proyecto consiste en la elaboración y caracterización de mezclas de polímero-cera, constituidas por una serie de diferentes porcentajes de los compuestos principales, HDPE y cera parafina, para su potencial empleo como materiales de cambio de fase. A raíz de las necesidades planteadas por parte del actual mercado y los retos multidisciplinares a los que nos enfrentamos en el futuro de campos como, por ejemplo, el de la edificación, tanto Universidades, co...

  12. LAS LIPOPROTEÍNAS DE ALTA DENSIDAD: PROTECTORAS VASCULARES CONTRA LA ATEROSCLEROSIS / High-density lipoproteins: vascular guards against atherosclerosis

    Directory of Open Access Journals (Sweden)

    Yosit Ponce Gutiérrez

    2013-10-01

    Full Text Available Resumen El incremento de los niveles de lipoproteínas de alta densidad y sus potenciales beneficios en la aterosclerosis ha sido motivo para la realización de este artículo, en el que se efectúa una revisión sobre la información médica más reciente que existe sobre el tema y su posterior actualización. Se describen la estructura de estas lipoproteínas, sus efectos vasculares ateroprotectores, el transporte reverso de colesterol, y se exponen las nuevas estrategias que permiten incrementar sus concentraciones en el organismo, ya que estudios recientes indican que estabilizan las placas de ateroma de una manera acelerada, por lo que constituyen una novedosa alternativa terapéutica en los pacientes de alto riesgo. De esta forma se consolidan los conocimientos sobre las lipoproteínas de alta densidad, con el fin de brindar una atención de más calidad en la prevención, control y tratamiento de esta frecuente enfermedad. / Abstract Increasing levels of high-density lipoproteins and their potential benefits in Atherosclerosis motivated us to write this article in order to update knowledge on this topic. The structure of these lipoproteins is described, as well as their atheroprotective vascular effects and the reverse cholesterol transport. New strategies to increase their concentration in the body are presented, as recent studies indicate that they stabilize atherosclerotic plaques in an expedited manner. Therefore, it constitutes a novel therapeutic alternative in high risk patients. This will update the knowledge on highdensity lipoproteins, in order to provide a better quality care in the prevention, control and treatment of this common disease.

  13. Appraisal of a HDPE internal liner; Avaliacao de revestimento interno de duto em polietileno de alta densidade

    Energy Technology Data Exchange (ETDEWEB)

    Meniconi, Luiz C.M.; Perrut, Valber A.; Castellares, Lizabeth G. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Medeiros, Raimundo C. [PETROBRAS, SP (Brazil). Setor de Qualificacao e Certificacao (SEQUI)

    2005-07-01

    The mechanical properties of a high density polyethylene were evaluated by tensile and tearing tests, after ageing for up to 28 days of immersion in crude oil at 55 deg C. After that, the performance of the polymer as a liner of a metallic pipeline was appraised. A situation was simulated in which an infinitely long defect was supposed to exist along the inner bottom of the pipeline, due to pitting corrosion. Under internal pressure, the liner is pushed and bent against the empty space behind it, causing a tensile stress on its outer surface. The abrasion between the liner and the pipeline during liner installation can create scratches in the liner. The scratches would behave as notches for the initiation of a propagating defect, under the tensile load mentioned above. Finite Element Modeling was used to define the limit values of internal pressure, liner thickness and defect size that would cause defect propagation. The simulation was performed for typical values of pipeline diameter, defect size and liner thickness. (author)

  14. LEVITACIÓN MAGNÉTICA EN FLUIDOS DE ALTA VISCOSIDAD Y DENSIDAD

    Directory of Open Access Journals (Sweden)

    ELIANA RONDÓN

    2010-01-01

    Full Text Available Este artículo describe el diseño de un sistema prototipo de levitador magnético que opera sumergido en un aceite dieléctrico de viscosidad y densidad sustancialmente superior a la del aire. Se implementó un compensador de atraso de fase en cascada con la planta con el fin de posicionar un cascaron esférico metálico en un punto en particular dentro del aceite. Se analizó el comportamiento del sistema al variar la viscosidad mediante la variación de la temperatura del fluido, observándose que a medida que su viscosidad disminuye con el aumento de temperatura, el sistema se torna inestable, mientras que para el caso del incremento de su viscosidad, el tiempo de respuesta se torna muy grande y el sistema responde lentamente. El sistema se simuló obteniéndose resultados que concuerdan estrechamente con los resultados del prototipo experimental que sirvió para validar el diseño.

  15. Cinética de cristalização não-isotérmica de resíduos de polietileno de alta densidade (PEAD)

    OpenAIRE

    Helson Moreira da Costa; Mônica Calixto de Andrade; Milena Diniz Lessa; Valéria Dutra Ramos

    2014-01-01

    Nesta investigação, diversos resíduos incolores ou coloridos pós-consumo de polietileno de alta densidade (PEAD) foram caracterizados através do índice de fluidez (MFI) e da calorimetria exploratória diferencial (DSC). A equação de Avrami modificada por Jeziorny, e os modelos de Kissenger e Friedman foram utilizados para descrever a cinética de cristalização não-isotérmica das amostras. Foi verificado que os pigmentos presentes no PEAD têm diferentes habilidades nucleantes durante o processo ...

  16. EVALUACIÓN DE LA PRODUCCIÓN DE PAPA CRIOLLA Solanum phureja CLON PAISA EN CONTENEDORES DE POLIETILENO DE ALTA DENSIDAD BAJO EL MARCO DE AGRICULTURA URBANA

    OpenAIRE

    Daniel Andrés Vega Castro

    2014-01-01

    Con el fin de evaluar la producción de papa criolla Solanum phureja clon Paisa en el contexto urbano, se desarrolló una investigación pionera de tipo descriptiva en la cual se evaluaron las siguientes variables: incidencia de plagas, peso en fresco por contenedor, peso fresco total y peso por clasificación comercial. Se utilizaron contenedores de doble fondo de polietileno de alta densidad y técnicas agroecológicas de producción, de las cuales se destaca la fertilización ...

  17. Densidad de ungulados en bosques de baja y alta presión de caza en el nororiente de la Amazonía peruana

    Directory of Open Access Journals (Sweden)

    Rolando Aquino

    2015-01-01

    Full Text Available Se proporciona información sobre tamaño de rebaño en pecaríes y densidad poblacional de éstos y otros ungulados para los bosques de baja y alta presión de caza del nororiente peruano. Durante el recorrido de 610 km de transecto de Noviembre-Diciembre 2012 en bosques de baja presión de caza y de 1218 km desde Febrero-Junio y Agosto-Octubre 2013 en bosques de alta presión de caza, fueron registrados 76 y 40 encuentros pertenecientes a seis y cinco especies, respectivamente; siendo los más comunes Pecari tajacu (35% y Mazama americana  (28%. El tamaño de rebaño en P. tajacu varió desde 2 a 8 individuos (tamaño promedio: 3,4±1,6 a 6±1,2. La densidad poblacional estimada para los ungulados fueron más altas en bosques de baja presión de caza sobresaliendo Tayassu pecari con 23,8 individuos/km2, seguido por P. tajacu con 14,4 individuos/km2, en tanto que la más baja fue para Tapirus terrestris (0,08 individuos/km2 y correspondió a los bosques de alta presión de caza. En los bosques de baja presión de caza, los encuentros más frecuentes con ungulados ocurrieron en el palmal de altura (46% y palmal de planicie (31%, en tanto que en el pantano arbóreo no hubo encuentros.

  18. Cinética de cristalização não-isotérmica de resíduos de polietileno de alta densidade (PEAD

    Directory of Open Access Journals (Sweden)

    Helson Moreira da Costa

    2014-08-01

    Full Text Available Nesta investigação, diversos resíduos incolores ou coloridos pós-consumo de polietileno de alta densidade (PEAD foram caracterizados através do índice de fluidez (MFI e da calorimetria exploratória diferencial (DSC. A equação de Avrami modificada por Jeziorny, e os modelos de Kissenger e Friedman foram utilizados para descrever a cinética de cristalização não-isotérmica das amostras. Foi verificado que os pigmentos presentes no PEAD têm diferentes habilidades nucleantes durante o processo de cristalização, bem como diferentes efeitos sobre a taxa de cristalização e a energia de ativação necessária para o transporte de segmentos macromoleculares para a superfície do cristal em crescimento.

  19. Characterization of high energy milled UHMWPE and its blends with HDPE;Caracterizacao do PEUAMM e blendas de PEAD e PEUAMM processado via moagem de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Carlos A.S. de; Ditzel, Fernanda I.; Gabriel, Melina C.; Pinheiro, Luis A.; Carvalho, Benjamim de M.; Cintho, Osvaldo M., E-mail: 8carloslima8@gmail.co [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil)

    2009-07-01

    The ultra-high molecular weight polyethylene (UHMWPE) has many excellent properties as high impact resistance, low abrasion and low coefficient of friction. However, it has a high viscosity which makes its processing by conventional methods more difficult. The purpose of the present work was to study the high energy mechanical milling of UHMWPE powder in an Attritor type mill at different times of milling. Subsequently, blends of HDPE with UHMWPE were prepared. The milled UHMWPE powder was characterized by SEM, XRD, DSC, FRX and apparent density. Specimen of blends in different concentrations and its polymeric films were prepared, which were characterized by optical microscopy with polarized light. Thus it was possible to observe that the milling time influences the morphological, chemical and physical features of UHMWPE and that the blend of HDPE with milled UHMWPE showed better dispersion of the PEUAMM than the blend of HDPE with non-milled UHMWPE. (author)

  20. Compósitos de partículas de madeira de Eucalyptus grandis, polipropileno e polietileno de alta e baixa densidades Composites of Eucalyptus grandis wood, polypropylene, and high and low-density polyethylene particles

    OpenAIRE

    Emerson Gomes Milagres; Benedito Rocha Vital; Ricardo Marius Della Lúcia; Alexandre Santos Pimenta

    2006-01-01

    Este trabalho teve como objetivo determinar as propriedades de painéis fabricados com mistura de partículas de madeira de Eucalyptus grandis, polietileno de alta densidade, polietileno de baixa densidade e polipropileno. Empregaram-se duas formulações adesivas (uréia-formaldeído e uréia-formaldeído contendo 0,5% de epóxi). De modo geral, as propriedades dos painéis foram afetadas pela composição das partículas. Os painéis com melhores propriedades foram fabricados com 75% de partículas de mad...

  1. ALTAS DENSIDADES DE PLANTIO NA CULTURA DO ABACAXI CV. SMOOTH CAYENNE, SOB CONDIÇÕES DE SEQUEIRO HIGH PLANTING DENSITY FOR THE SMOOTH CAYENNE PINEAPPLE CROP, GROWN UNDER RAINFED CONDITIONS

    OpenAIRE

    LUCIANA LIMA DE ALMEIDA SANTANA; DOMINGO HAROLDO REINHARDT; GETÚLIO AUGUSTO PINTO DA CUNHA; RANULFO CORREIA CALDAS

    2001-01-01

    No Brasil têm-se usado densidades de plantio relativamente baixas para a obtenção de frutos grandes, com reflexos negativos na produtividade da cultura do abacaxi. No entanto, frutos cada vez menores têm sido comercializados no mercado internacional, o que poderá também ocorrer no mercado nacional. Este trabalho teve o objetivo de avaliar o efeito de altas densidades em sistemas de plantio em filas duplas sobre a produção quantitativa e qualitativa de abacaxi cv. Smooth Cayenne, sob condições...

  2. Efeito dos solventes orgânicos sobre o comportamento físico-químico do polietileno de alta densidade (PEAD e polipropileno (PP

    Directory of Open Access Journals (Sweden)

    Thieres Magaive Costa Pereira

    2014-06-01

    Full Text Available O mercado brasileiro de embalagens empregado ao armazenamento de petróleo e seus derivados vem crescendo a cada ano, sendo constituídas basicamente por polietileno de alta densidade (PEAD e polipropileno (PP. Contudo durante o armazenamento, a matriz polimérica fica exposta ao óleo, comprometendo suas propriedades físicas e consequentemente a durabilidade do material. Portanto, estudos relacionados com a interação entre solventes orgânicos e a matriz polimérica tornam-se importantes. Neste trabalho, a interação do PEAD e PP com diferentes solventes apolares (tolueno, n-heptano, n-decano e n-tetradecano foram estudadas em função da temperatura (25, 50 e 80 ºC. Os valores de ganho de massa, coeficientes de difusão, sorção, permeabilidade e parâmetros de mecanismo de transporte foram calculados. O ganho de massa observado para o PP foi maior do que para o PEAD, em todas as temperaturas, sendo que o tolueno foi o solvente responsável pelo maior ganho de massa, atingindo o equilíbrio em um menor intervalo de tempo. Esse resultado corrobora com os valores de coeficiente de difusão e de permeabilidade, que aumentaram na seguinte ordem: n-heptano > n-decano > n-tetradecano. Uma ordem inversa foi observada para os solventes alifáticos quando os valores de coeficiente de sorção foram calculados. O mecanismo de transporte foi também estudado através da regressão dos dados de sorção, sendo classificado como anômalo.

  3. Avaliação do efeito de um óleo parafínico sobre o comportamento físico-químico de tubulações de polietileno de alta densidade Evaluation of the effect caused by a paraphinic oil on the physicochemical behavior of high-density polyethylene pipes

    Directory of Open Access Journals (Sweden)

    Amélia A. U. Torres

    2010-01-01

    Full Text Available Nesse trabalho são investigados os efeitos causados por um óleo parafínico sobre o comportamento físico-químico de dutos de polietileno de alta densidade (PEAD. Os efeitos causados nos dutos de PEAD foram avaliados em função do tempo e da temperatura de exposição através de análises gravimétrica e termogravimétrica e por espectroscopia no infravermelho. Os dados gravimétricos puderam ser satisfatoriamente descritos pela Lei de Fick. Os resultados de FTIR indicaram que não ocorreram modificações estruturais importantes no PEAD exposto a esse óleo e que o processo de envelhecimento do PEAD foi do tipo físico, já que nenhuma alteração na estrutura química do polímero foi detectada.The effects caused by a paraphinic oil on the physicochemical behavior of high-density polyehtylene pipes were investigated, as a function of time and temperature. These effects were evaluated by thermogravimetric and gravimetric analysis and by FTIR. The gravimetric data were satisfactorily described using the Fick's law, and the FTIR results showed that no main structural modifications have occurred after exposure of the HDPE pipes to this oil. From the results obtained it was concluded that physical aging was occurring, since the chemical structure of the polymer was not altered.

  4. Ingeniería de innovación aplicada a empresa productora de empaques flexibles en polietileno de alta y baja densidad y de propileno con impresión y sin impresión

    OpenAIRE

    Jesús David Castañeda A.; Alejandro Vásquez

    2006-01-01

    Este artículo tiene como finalidad presentar los resultados obtenidos al aplicar los métodos o técnicas de innovación determinados en la investigación Ingeniería de innovación para Pyme metalmecánica. La empresa escogida fabrica empaques flexibles de polietileno de alta y baja densidad y de polipropileno con impresión y sin impresión. El análisis se centra en dos variables que afectan significativamente el proceso y la productividad de la empresa: el desperdicio ...

  5. Compósitos de partículas de madeira de Eucalyptus grandis, polipropileno e polietileno de alta e baixa densidades Composites of Eucalyptus grandis wood, polypropylene, and high and low-density polyethylene particles

    Directory of Open Access Journals (Sweden)

    Emerson Gomes Milagres

    2006-06-01

    Full Text Available Este trabalho teve como objetivo determinar as propriedades de painéis fabricados com mistura de partículas de madeira de Eucalyptus grandis, polietileno de alta densidade, polietileno de baixa densidade e polipropileno. Empregaram-se duas formulações adesivas (uréia-formaldeído e uréia-formaldeído contendo 0,5% de epóxi. De modo geral, as propriedades dos painéis foram afetadas pela composição das partículas. Os painéis com melhores propriedades foram fabricados com 75% de partículas de madeira e 25% de partículas de polietileno de alta densidade. A adição de epóxi ao adesivo uréico aumentou os valores do módulo de ruptura, dureza Janka, e reduziu o inchamento, em espessura, de alguns painéis. As propriedades mecânicas da maioria dos painéis, exceto o módulo de elasticidade, ultrapassaram os valores mínimos estabelecidos na norma ANSI/A1-208/93.The objective of this work was to establish the properties of particleboards fabricated with blends of Eucalyptus grandis, low-density polyethylene, high-density polyethylene and polypropylene particles. Two adhesives formulations were used (urea-formaldehyde and urea-formaldehyde plus 0,5% of epoxy adhesive. Panel properties were affected by particle composition. Panels with best properties were fabricated with 75% of wood particles and 25% of high density polypropylene. The addition of epoxy to the urea-formaldehyde adhesive improved of the values of modulus of rupture, hardness and reduced the amount of thickness swelling. Except for the modulus of elasticity, board properties meet grade M-2 ANSI/A1-208/93 requirements.

  6. Substituição da fibra de vidro por fibra de bananeira em compósitos de polietileno de alta densidade: parte 1. Avaliação mecânica e térmica Mechanical and thermal behavior of composites based on high density polyethylene and banana tree fiber

    Directory of Open Access Journals (Sweden)

    Thiago S. Gomes

    2013-01-01

    Full Text Available A utilização de resíduo de fibra natural em substituição à fibra de vidro foi avaliada. Foram estudados compósitos de polietileno de alta densidade, HDPE, e fibra de bananeira com 10, 20, 30 e 40% (m/m de fibra. Compósitos com fibra de vidro, mesma matriz polimérica e nas mesmas proporções, foram preparados para comparação. Os compósitos foram obtidos em extrusora dupla-rosca co-rotacional interpenetrante e os corpos de prova foram preparados por injeção. As propriedades mecânicas sob tração, flexão e impacto foram avaliadas. As propriedades térmicas foram analisadas por calorimetria diferencial de varredura (DSC e análise termogravimétrica (TG. A incorporação de fibra de bananeira no HDPE resultou no aumento de cristalinidade do polímero. Houve, também, considerável aumento no grau de reforço mecânico nos compósitos pela incorporação da fibra natural. Foi possível comprovar a substituição da fibra de vidro pela fibra de bananeira em determinados percentuais, quando misturados ao HDPE, sem prejuízo às propriedades. A análise termogravimétrica dos compósitos mostrou que o início de degradação se deu numa faixa de temperatura intermediária entre a da fibra e a da matriz polimérica.The use of banana tree fiber instead of glass fiber in polyethylene composites was evaluated. Composites of high density polyethylene with 10, 20, 30 and 40 wt. % of banana fiber were investigated. For comparison, composites with glass fiber, with the same polymeric matrix and proportions, were prepared. The samples were produced using an intermeshing co-rotating twin-screw extruder and injection molding. The mechanical properties investigated were the tensile, flexural and impact resistances of the composite. Thermal analyses were carried out by differential scanning calorimetry (DSC and thermogravimetry (TG. The incorporation of fiber resulted in an increase in the composite degree of crystallinity. A considerable increase

  7. Consumo de alimentos de alta densidad energética en los beneficiarios del programa Oportunidades. El caso del Área Metropolitana de Monterrey

    Directory of Open Access Journals (Sweden)

    Óscar Alfonso Martínez Martínez

    2012-01-01

    refrescos y frituras, entre los beneficiarios y no beneficiarios de dicho programa. Se encontró que no existen diferencias estadísticamente significativas en su consumo, pero sí que las ingestas son altas para ambos grupos.

  8. Modificação química de celulose para utilização em mistura com polietileno de alta densidade

    OpenAIRE

    Ciulik, Claudio Batista

    2010-01-01

    Resumo: O polietileno, um dos polímeros mais usados no mundo é também, um dos principais resíduos poliméricos encontrados nos lixões dos grandes centros urbanos. Este e outros problemas como a pequena resistência ao desgaste, alta transmissão de odores e baixa resistência à migração de óleos e gorduras, torna promissor o estudo de novas composições com este termoplástico, agregando ao mesmo, substâncias que enriqueçam suas propriedades tal como a celulose. Sabendo das grandes diferenças de pr...

  9. Nanocompósitos de blendas HDPE/LLDPE e OMMT - Parte II: avaliação das propriedades térmica, óticas e de transporte a gases

    Directory of Open Access Journals (Sweden)

    Fabio R. Passador

    2013-01-01

    Full Text Available Nanocompósitos de blendas de polietileno de alta densidade (HDPE com polietileno linear de baixa densidade (LLDPE e OMMT (montmorilonita organofílica foram preparados sob fusão em extrusora de dupla-rosca, utilizando HDPE-g-MA como agente compatibilizante. Os nanocompósitos foram caracterizados através das propriedades térmicas, óticas e de transporte de gases. A blenda HDPE/LLDPE e os nanocompósitos das blendas HDPE/LLDPE como esperado comportam-se como barreira ao vapor de água e são permeáveis ao CO2 e O2. A adição de nanoargila modificou o grau de cristalinidade da matriz polimérica dos nanocompósitos e a diminuição do coeficiente de permeabilidade foi atribuída ao aumento do grau de cristalinidade e do aumento ao caminho difusional para as moléculas do gás passarem pelo filme polimérico. O caminho difusional mais longo devido ao aumento da tortuosidade está relacionado a uma boa dispersão da carga inorgânica, boa molhabilidade desta pela matriz e forte interações na interface. Modelos teóricos de permeabilidade propostos por Nielsen e Bharadwaj foram utilizados para estimar a razão de aspecto da nanoargila nos nanocompósitos e forneceram resultados que se correlacionam bem com as morfologias observadas por microscopia eletrônica de transmissão.

  10. Compensatory growth of Malaysian prawns reared at high densities during the nursery phase Crescimento compensatório em camarões-da-malásia cultivados sob altas densidades durante a fase de berçário

    Directory of Open Access Journals (Sweden)

    H.L.A. Marques

    2011-04-01

    Full Text Available The objective of this work was to verify the occurrence of compensatory growth in Malaysian prawn (Macrobrachium rosenbergii reared in pens, after being stocked in cages under high densities during nursery phase. The experiment was carried out in 0.5 m² cages and 2-m² pens set in natural bottom pond with 2,400 m². Prawn post-larvae (PL with an average weight of 0.026 ± 0.012 g (nursery phase were initially stocked in 16 cages at the densities of 50, 400, 800 and 1,200 PL m-2. Sixty days later, prawns were transferred to 16 growing pens, at the density of 12 prawns m-2. Initial average weight of the prawn in this phase was the final average weight registered in the nursery phase, as follows: 50 PL m-2 = 2.3 ± 0.3 g; 400 PL m-2 = 0.5 ± 0.03 g; 800 PL m-2 = 0.3 ± 0.05 g and 1,200 PL m-2 = 0.1 ± 0.01 g. Commercial rations for prawns (35% crude protein were given once a day, in the afternoon. After 244 days, survival, average weight and biomass did not differ significantly among prawns with different initial average weight. Relative growth rate was significantly greater in prawns previously stocked at 1,200 PL m-2 and feed conversion efficiency was significantly better for those previously stocked at 400 and 1,200 PL m-2. These results suggest the existence of partial compensatory growth in M. rosenbergii, what can successfully carry on stocking of prawns of this species at high densities in the nursery phase.Este trabalho foi realizado com o objetivo de verificar a ocorrência de crescimento compensatório em camarões-da-malásia (Macrobrachium rosenbergii cultivados em cercados, após serem estocados em gaiolas sob altas densidades durante a fase de berçário. O experimento foi conduzido em gaiolas com 0,5 m² e cercados com 2 m² instalados em um viveiro de fundo natural com 2.400 m². Pós-larvas (PL de camarões com peso médio de 0,026 ± 0,012 g (fase de berçário foram inicialmente estocadas em 16 gaiolas, nas densidades de 50, 400

  11. ALTAS DENSIDADES DE PLANTIO NA CULTURA DO ABACAXI CV. SMOOTH CAYENNE, SOB CONDIÇÕES DE SEQUEIRO HIGH PLANTING DENSITY FOR THE SMOOTH CAYENNE PINEAPPLE CROP, GROWN UNDER RAINFED CONDITIONS

    Directory of Open Access Journals (Sweden)

    LUCIANA LIMA DE ALMEIDA SANTANA

    2001-08-01

    Full Text Available No Brasil têm-se usado densidades de plantio relativamente baixas para a obtenção de frutos grandes, com reflexos negativos na produtividade da cultura do abacaxi. No entanto, frutos cada vez menores têm sido comercializados no mercado internacional, o que poderá também ocorrer no mercado nacional. Este trabalho teve o objetivo de avaliar o efeito de altas densidades em sistemas de plantio em filas duplas sobre a produção quantitativa e qualitativa de abacaxi cv. Smooth Cayenne, sob condições de sequeiro. Densidades de plantio, variando de 51.280 plantas/ha a 100.000 plantas/ha, foram estudadas em delineamento experimental de blocos casualizados, com cinco repetições e doze tratamentos, distribuídos em esquema fatorial 4 x 3, correspondendo a quatro combinações de espaçamentos entre linhas duplas e entre linhas simples na fila dupla (90cm x 40 cm, 90 cm x 30 cm, 80 cm x 30 cm , 70 cm x 30 cm e três espaçamentos entre plantas nas linhas de plantio (30 cm, 25 cm, 20 cm. A análise de variância determinou diferença estatística apenas para a produtividade, em função do espaçamento entre plantas na linha de plantio, sendo mais elevada para o espaçamento de 20 cm. O peso do fruto, as suas dimensões e a sua qualidade (açucares, acidez, teor de suco, relação açúcares/acidez não foram significativamente influenciados pelas densidades de plantio estudadas, mantendo-se dentro dos padrões da cultivar. Para cada aumento de 10.000 plantas por hectare, a produtividade cresceu em 8,27 t/ha e o peso médio do fruto caiu 102 g. Nas condições ambientais dos Tabuleiros Costeiros do Norte da Bahia, a cultura do abacaxi cv. Smooth Cayenne apresenta potencial para uso em altas densidades de plantio, mesmo em cultivo de sequeiro, podendo-se atingir produtividade acima de 80t/ha e peso médio do fruto superior a 1,0 kg.In Brazil, relatively low planting densities have been used to obtain large fruits, with negative effects on pineapple

  12. Nanocompósitos poliméricos de polietileno de alta densidade contendo hidróxidos duplos lamelares intercalados com ânions derivados de corantes azo

    Directory of Open Access Journals (Sweden)

    Ademir Zimmermann

    2014-06-01

    Full Text Available O presente trabalho descreve a síntese e caracterização de hidróxidos duplos lamelares (HDL de Zn/Al na razão molar 2:1, os quais foram intercalados com íons cloreto hidratados e ânions derivados dos corantes azo alaranjado de metila (AM e alaranjado II (AII. Após caracterização, os materiais foram utilizados como cargas em polietileno de alta densidade (PEAD e nanocompósitos foram preparados por extrusão e injeção, seguindo a norma ASTM D638-10. Os teores de cargas variaram de 0,1 até 2% (incluindo-se os sais de sódio dos corantes e os nanocompósitos homogêneos foram avaliados em relação as suas propriedades estruturais, térmicas e mecânicas. De modo geral, após a adição das cargas existe somente uma pequena influência na temperatura de fusão e cristalização do PEAD. Para os HDLs contendo o pigmento intercalado com o ânion do corante AM e sais de sódio de ambos os corantes, as propriedades mecânicas apresentaram leve aumento do módulo e tensão de ruptura e diminuição do alongamento em relação ao polímero puro e um comportamento inverso foi observado para o ânion AII, além do HDL contendo ânions cloreto hidratados.

  13. Preparação e caracterização de biocompósitos baseados em fibra de curauá, biopolietileno de alta densidade (BPEAD e polibutadieno líquido hidroxilado (PBHL Preparation and characterization of biocomposites based on curaua fibers, high-density biopolyethylene (HDBPE and liquid hydroxylated polybutadiene(LHPB

    Directory of Open Access Journals (Sweden)

    Daniele O. Castro

    2013-01-01

    Full Text Available Neste trabalho, foram utilizadas fibras de curauá como reforço de matriz termoplástica de biopolietileno de alta densidade. O polietileno foi obtido por polimerização de eteno, gerado do etanol de cana de açúcar. Este polímero é também chamado de biopolietileno (BPEAD, por ser preparado a partir de material oriundo de fonte natural. Desta forma, pretendeu-se contribuir para desenvolver materiais que, dentre outras propriedades, causem menor emissão de CO2 para a atmosfera na sua produção, utilização e substituição, comparativamente a outros materiais. Adicionalmente, polibutadieno líquido hidroxilado (PBHL foi acrescentado à formulação do compósito, visando a um aumento na resistência à propagação da trinca durante impacto. Os compósitos e as fibras foram caracterizados por várias técnicas, tais como microscopia eletrônica de varredura (MEV, Calorimetria Exploratória Diferencial (DSC, Termogravimetria (TG, além da caracterização dos compósitos quanto à Análise Térmica Dinâmico-Mecânica (DMTA, propriedades mecânicas (impacto e flexão e absorção de água. A presença das fibras de curauá diminuiu algumas propriedades do BPEAD, como resistência ao impacto. A análise de DMTA mostrou que as fibras geram material mais rígido. Pode-se considerar que a introdução de PBHL na formulação do material foi eficiente, levando a uma resistência ao impacto do compósito BPEAD/PBHL/Fibra maior do que a do compósito BPEAD/Fibra.In this work, curaua fibers were used in the reinforcement of a high-density (HDPE thermoplastic matrix. The polyethylene used was obtained by polymerization of ethene produced from sugarcane ethanol. This polymer, also called high-density biopolyethylene (HDBPE, was prepared from a natural source material. The aim was to contribute to developing materials which could lead to smaller release of CO2 into the atmosphere in comparison to other materials. Additionally, liquid

  14. Características de compósitos laminados manufaturados com polietileno de alta densidade (PEAD e diferentes proporções de casca de arroz e partículas de madeira

    Directory of Open Access Journals (Sweden)

    Dalva Teresinha Pauleski

    2007-01-01

    Full Text Available The objective of this work was to analyse the feasibility of the utilization of rice husks and wood particles in the manufacture of wood plastic composites, in a way similar to particleboard fabrication. The composites were made with rice husks and Eucalyptus grandis wood particles, pure or mixed, in proportions of 0, 25, 50, 75 and 100% of ovendry weight. High density polyethylene (HDPE was used as matrix in the manufacture in three proportions: 60, 75, and 90%. Bending properties, internal bond, water absorption and thickness swelling after 24 hours of water soaking and after 15 soaking cycles were evaluated. The values of bending properties were influenced by the density of the composite. In the case of internal bond, the values were within the limits established by commercial particleboard standards, being the HDPE proportion the parameter of higher correlation with this property. Rice husk caused lower thickness swelling and, independently of the type of raw material utilised, the values decreased with the increase of HDPE. Combinations with larger percentages of HDPE presented minimal values or, in some cases, null of water absorption. For the water absorption and thickness swelling after 15 cycles the behavior was similar to that of the 24 hour period. Results allowed concluding that the composites made with HDPE, rice husks and wood particles pure or mixed present good quality, evidencing the adequacy of these raw material and process in manufacturing this type of panel.

  15. Estrutura, metabolismo e funções fisiológicas da lipoproteína de alta densidade Structure, metabolism and physiologic functions of high-density lipoproteins

    Directory of Open Access Journals (Sweden)

    Emerson Silva Lima

    2006-06-01

    Full Text Available Diversos estudos clínicos, epidemiológicos e experimentais têm mostrado de maneira incontestável a relação entre dosagem sérica dos níveis de lipoproteína de alta densidade (HDL e doença cardiovascular. Baixos níveis de HDL estão presentes em aproximadamente 10% da população e representam um dos mais freqüentes achados de dislipidemia nos pacientes com doença arterial coronariana (DAC. Esses níveis reduzidos de HDL poderiam ser incapazes de efetivamente eliminar o excesso de colesterol das paredes vasculares, contribuindo para o fenômeno inflamatório que caracteriza a patogênese da aterosclerose nas suas fases iniciais. Outros inúmeros estudos têm convincentemente mostrado que a HDL também exerce efeitos diretos sobre os processos inflamatórios, por exemplo, através da modulação da expressão de diversas proteínas de fase aguda. Além disso, a HDL também possui diversos outros efeitos antiaterogênicos, como efeitos antioxidantes, inibição da agregação plaquetária e da migração de monócitos. O presente artigo faz uma revisão da literatura atual sobre o metabolismo da HDL e suas principais ações na prevenção da doença arterial coronariana.Several experimental, clinical and epidemiological researches have shown the incontestable causal relationship between low high-density lipoprotein (HDL plasma concentrations and cardiovascular pathology on an atherosclerotic basis. Low HDL levels characterize about 10% of the general population and they represent the most frequent dyslipidemia in patients with coronary artery disease. Reduced HDL concentrations would be unable to effectively eliminate the cholesterol excess at the vascular wall, contributing to the inflammatory phenomenon that characterizes the pathogenesis of atherosclerosis since its initial phases. Results of numerous studies reasonably allow supposing that HDL is able to exert, also directly, anti-inflammatory actions through the modulation of

  16. Preparation and characterization of high density polyethylene and residual fibre of Attalea funifera Mart (piacava) composites; Preparacao e caracterizacao de compositos de polietileno de alta densidade com residuos de fibras de piacava da especie Attalea funifera Mart

    Energy Technology Data Exchange (ETDEWEB)

    Agrela, Sara P.; Guimaraes, Danilo H.; Jose, Nadia M., E-mail: saraagrela@hotmail.co [Universidade Federal da Bahia (GECIM/IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais; Carvalho, Gleidson G.P. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Escola de Medicina Veterinaria. Dept. de Producao Animal; Carvalho, Ricardo F. [Universidade Federal da Bahia (EP/UFBA), Salvador, BA (Brazil). Escola Politecnica. Curso de Mestrado em Engenharia Ambiental Urbana

    2009-07-01

    The use of natural fiber reinforcement thermoplastic polymer is continuously increasing. This fact is manly due to its advantages as low cost, availability, recyclability, low energy demand and then environmental appeal if compared to synthetics fibers. The composites were prepared in different fiber volume ratios (5%, 10% and 20%) mixed with high density polyethylene (HDPE) and heated at 190 deg C. Thermogravimetric analysis and differential scanning calorimetry were used to investigate thermal stability. The composites structure was characterized by Fourier Transform Infrared spectroscopy, X-ray diffractometry. Fiber and residue of piassava (Attalea funifera Mart) chemical composition were determined by Van Soest Method. The results indicate that thermo stability of the composites of HDPE prepared with fiber volume ratios up to 20% is only slightly lowered. (author)

  17. Fertilización de base en un cultivo inicial de pecan con dos marcos de plantación de alta densidad Effect of different fertilization strategies on pecan growth parameters under two high density plantation frames

    Directory of Open Access Journals (Sweden)

    Lidia Giuffré

    2011-07-01

    Full Text Available El pecán, Carya illinoensis Koch, es una especie cuyo fruto es reconocido como un alimento altamente saludable. Su cultivo se encuentra en expansión en la Argentina pero existen muy pocas investigaciones sobre fertilización y sistemas de plantación. Los objetivos del trabajo fueron caracterizar algunas propiedades físico-químicas y químicas de un suelo en el que se inicia un cultivo de pecán, y comparar tratamientos de fertilización de base (FB en dos marcos de plantación de alta densidad (MP. Se realizó una plantación de pecán en Villanueva (provincia de Buenos Aires, sobre un suelo Hapludol taptoárgico, con dos marcos de plantación: 10 x 10 m (marco real: MR y 8 x 8 m (tresbolillo: TR. El diseño del experimento fue en parcelas divididas con cuatro repeticiones. La parcela principal fueron los dos marcos de plantación, y las subparcelas fueron los distintos tratamientos de fertilización base: Compost (C, Fósforo (P, Nitrógeno (N y Control sin fertilización base (T. Las determinaciones para evaluar el crecimiento de las plantas de pecán fueron: la altura de las plantas y el diámetro del tronco. Con respecto a la fertilidad del suelo, la fertilización fosforada y el agregado de compost permitieron aumentar significativamente los niveles de P-Bray. El tratamiento con fertilización orgánica: compost, presentó un incremento significativo en altura de los pecanes en el marco de plantación 8 x 8 m, que no se manifestó en ningún caso en los diámetros del tronco, con una interacción MP x FB significativa (P=0,01 para la variación de altura al primer año. La variación del volumen del árbol durante el año de experimentación no presentó efectos significativos según el marco de plantación ni la fertilización base aplicada.The fruit of the pecan tree, Carya illinoensis Koch, is considered a very healthy food. In Argentina, pecan cultivation has been expanding rapidly but very little research has been conducted on

  18. Caracterização estrutural de nanocompósitos de blendas HDPE/LLDPE e OMMT obtidos por diferentes sequências de mistura Structural characterization of HDPE/LLDPE and OMMT blend-based nanocomposites obtained by different blending sequences

    Directory of Open Access Journals (Sweden)

    Fabio R. Passador

    2012-01-01

    Full Text Available Nanocompósitos de blendas de polietileno de alta densidade (HDPE com polietileno linear de baixa densidade (LLDPE e OMMT (montmorilonita organofílica foram preparados em um reômetro de torque, utilizando-se como sistema compatibilizante uma mistura de HDPE-g-MA e LLDPE-g-MA, ambos com 1% de anidrido maleico. O efeito de cinco sequências de mistura na formação da microestrutura dos nanocompósitos foi estudado. A caracterização estrutural foi realizada por análises de difração de raio X de alto ângulo (WAXD, microscopia eletrônica de transmissão (MET e comportamento reológico em regime permanente de deformação. Os resultados mostraram que a formação da microestrutura depende da ordem de mistura dos componentes e a utilização de mistura de dois agentes compatibilizantes miscíveis com os constituintes da matriz auxiliou na distribuição da polaridade, facilitando a dispersão das nanoargilas por toda a matriz. Dentre as sequências estudadas, as que a nanoargila foi primeiramente misturada com componentes de menor viscosidade e cristalinidade (LLDPE e/ou LLDPE-g-MA apresentaram melhor dispersão e distribuição da nanoargila na blenda polimérica.High density polyethylene/linear low density polyethylene (HDPE/LLDPE blend-based nanocomposites were prepared in a torque rheometer, using a mixture of HDPE-g-MA and LLDPE-g-MA both containing 1% of maleic anhydride as compatibilizer system. The effect from five blending sequences on the microstructure of the nanocomposites was investigated. The structural characterization was performed through wide angle X-ray diffraction (WAXD, transmission electron microscopy (TEM and rheological properties. The results showed that the formation of morphology is dependent on the sequence of nanocomposite preparation and that the use of a mixture of two compatibilizer agents, miscible with both components of the blend matrix, facilitated the dispersion of the nanoclay throughout the matrix. The

  19. Rejuvenecimiento de manos con ácido hialurónico de alta densidad: estudio prospectivo en 29 pacientes Hands rejuvenation with high density hyaluronic acid: prospective study in 29 patients

    Directory of Open Access Journals (Sweden)

    J.M. Alcolea

    2012-12-01

    Full Text Available El objetivo del presente estudio prospectivo es valorar a corto, medio y largo plazo, la eficacia en el rejuvenecimiento de las manos de la inyección subcutánea de ácido hialurónico (AH, Macrolane® 20, de alta densidad y partículas grandes, teniendo en cuenta el beneficio del tratamiento, la satisfacción de los pacientes y las posibles complicaciones. Este estudio se realizó entre mayo del 2010 y diciembre del 2011. Se seleccionaron 29 pacientes al azar entre 51 y 74 años de edad con fototipos II a IV, a los que se les inyectó AH para rejuvenecer las manos. La cantidad de AH inyectada en cada mano fue de 1 a 2 ml. Se realizaron controles sistemáticos en la 2ª semana, en los meses 1º, 3º, 6º, 9º y 12º. Se tuvieron en cuenta las complicaciones en cada paciente en todos los controles. En el primer control, en la 2ª semana, junto al examen clínico se practicó examen ecográfico a fin de determinar si sería necesaria una segunda inyección de AH. En cada uno de los controles los pacientes contestaron a un formulario para indagar sobre su grado de satisfacción con el tratamiento. Solo 1 paciente presentó edema y 3 tuvieron equimosis leve; 2 pacientes manifestaron dolor leve con las inyecciones y 2 requirieron una segunda inyección tras la valoración en la 2ª semana. La satisfacción de los pacientes en los controles superó la valoración clínica y fotográfica. En nuestra opinión, el rejuvenecimiento de las manos con este tipo de AH de grandes partículas tiene una baja tasa de complicaciones y es bien tolerado, con un alto grado de satisfacción por parte de los pacientes y una notable mejoría de los parámetros estudiados: arrugas, aspecto de la atrofia dérmica y subcutánea y disminución de los relieves óseos, tendinosos y venosos. La valoración tanto subjetiva como objetiva se hizo hasta el año de seguimiento con buenos resultados.The aim of this prospective study is to assess the efficacy of a high density

  20. Avaliação do efeito de um óleo parafínico sobre o comportamento físico-químico de tubulações de polietileno de alta densidade Evaluation of the effect caused by a paraphinic oil on the physicochemical behavior of high-density polyethylene pipes

    OpenAIRE

    Amélia A. U. Torres; José Roberto M. d'Almeida; Jean-Pierre Habas

    2010-01-01

    Nesse trabalho são investigados os efeitos causados por um óleo parafínico sobre o comportamento físico-químico de dutos de polietileno de alta densidade (PEAD). Os efeitos causados nos dutos de PEAD foram avaliados em função do tempo e da temperatura de exposição através de análises gravimétrica e termogravimétrica e por espectroscopia no infravermelho. Os dados gravimétricos puderam ser satisfatoriamente descritos pela Lei de Fick. Os resultados de FTIR indicaram que não ocorreram modificaç...

  1. Metodología para el diseño de diagnósticos interferométricos de alta resolución espacial para la medida de perfiles de densidad electrónica en plasmas de fusión: el interferómetro heterodino de haz expandido y de dos longitudes de onda del Stellarator TJ-II

    OpenAIRE

    Pedreira Conchado, Pablo

    2011-01-01

    Este trabajo de tesis doctoral desarrolla una metodología para el diseño de diagnósticos interferométricos multicanal para la medida de perfiles de densidad electrónica de alta resolución espacial en plasmas de fusión confinados magnéticamente y su validación a través del diseño de un diagnóstico para el stellarator TJ-II. A mediados del siglo XX surge la fusión termonuclear como una solución y alternativa a los problemas que se derivan del uso de los combustibles fósiles co...

  2. Compósitos de HDPE com resíduos de fibras têxteis. Parte I: caracterização mecânica HDPE composites with textile fibers waste. Part I: mechanical characterization

    Directory of Open Access Journals (Sweden)

    Maira Finkler

    2005-07-01

    Full Text Available Neste trabalho são apresentados e discutidos os resultados das propriedades mecânicas de novos materiais compósitos preparados com resíduos de fibras têxteis poliméricas e de polímeros commodities. As fibras naturais oferecem vantagens sobre as sintéticas, em termos de propriedades mecânicas e térmicas. Os compósitos foram preparados a partir da mistura de polietileno de alta densidade (HDPE e resíduos de fibras têxteis (50% algodão /50% acrílico em teores crescentes de 10 a 40%, em um misturador de alta velocidade, utilizando Surlyn 2601, Polybond 3009 e Polybond 1009 como agentes compatibilizantes. Corpos-de-prova para ensaios de tração, flexão e impacto foram produzidos a partir de chapas obtidas em uma prensa hidráulica. Os compósitos que utilizaram agentes compatibilizantes apresentaram os melhores resultados de resistência à tração e à flexão, principalmente com 5% do agente Polybond 3009 e 20 a 40% de resíduos de fibras têxteis.In this work, results of mechanical properties of new composites based on textile fiber residues from clothing industry and commodity polymers are discussed. Natural fibers offer some advantages over synthetic ones, regarding mechanical and thermal properties. The composites were produced by mixing high density polyethylene with the textile fibers (50% cotton /50% acrylic in increasing contents, from 10 to 40% in a thermokinetic mixer, using Surlyn 2601, Polybond 3009 and Polybond 1009 as coupling agents. The tensile, flexural and impact samples were produced by cutting sheets obtained in a hydraulic press. The composites with coupling agents showed good results of tensile and flexural strength, mainly with 5% of Polybond 3009 and 20-40% of textile fiber residues.

  3. Patella Alta

    OpenAIRE

    Cakmak, Mehmet; Taser, Omer; Karamehmetoglu, Mahmut; Domanic, Unsal

    2004-01-01

    Patella alta is investigated with Insall-Salvati method in lateral X-rays obtained with the knee in 30 flexion in 26 cases with recurrent dislocation of the patella and in 16 cases diagnosed to have chondromalasia. Patella alta is identified in 12 cases with recurrent dislocation of patella and in 9 cases with chondromalasia. Patella alta, which is one of the significaint consative agents of patella femoral instrability, is reviewed under the literature data.

  4. High population density survival of the sea urchin Diadema antillarum (Philippi 1845 to a category 5 hurricane in southern Mexican Caribbean Supervivencia de una alta densidad poblacional del erizo de mar Diadema antillarum (Philippi 1845 a un huracán categoría 5 en el sur del Caribe mexicano

    Directory of Open Access Journals (Sweden)

    Pablo Jorgensen

    2008-12-01

    Full Text Available The vulnerability of the sea urchin Diadema antillarum to the impact of the category 5 hurricane "Dean" was assessed at a back-reef area of Mahahual (Southern Mexican Caribbean. Seventy days after Dean, there was a high mean Diadema population density of 12.6 ± 4.3 (SD; from here forward ind m-2, with a large mean individual test diameter of 59.2 ±9.8 mm. This population was comparable to a previous report for the same area, just before the landfall of Dean on 21 August 2007. Immigration of adults from deeper fore-reef sites after Dean across the reef-crest was unlikely, considering the homing behavior displayed by tagged urchins. The degree of physical alteration of the habitat indicated that Diadema may survive higher hurricane-generated disturbances than those reported in previous works. These results have strong implications on the conservation of the Mexican Caribbean coral reefs since the Diadema populations surveyed have a high grazing activity and are persistent against hurricanes impact.La vulnerabilidad del erizo de mar Diadema antillarum al impacto del huracán categoría 5 "Dean" fue evaluada en el arrecife posterior de Mahahual, México. Setenta días después de la recalada de Dean fue estimada una alta densidad media poblacional de Diadema de 12.6 ind m-2 (DE = 4.3, con un elevado tamaño individual promedio de 59.2 mm de diámetro (DE = 9.8. Esta densidad fue comparable a la de un reporte previo para la misma zona, días antes del paso de Dean el 21 de agosto de 2007. Considerando la fidelidad al refugio mostrado por erizos marcados, la inmigración de adultos desde el arrecife anterior después del paso de Dean fue poco factible. El nivel de destrucción del hábitat indica que Diadema sería más persistente al impacto directo de huracanes que lo sugerido por estudios anteriores. Debido al elevado potencial de pastoreo de las poblaciones locales de Diadema, y a su persistencia al impacto de huracanes, los resultados de este

  5. FRACTIONATED CRYSTALLIZATION OF HDPE IN PS/POE/HDPE/SBS BLENDS

    Institute of Scientific and Technical Information of China (English)

    Ming-ming Ding; Xiao-ting Fu; Jing Cao; Qin Zhang; Chang-yue Yang; Qiang Fu

    2008-01-01

    The fractionated crystallization behavior of the minor dispersed HDPE phase in PS/POE/HDPE/SBS quaternaryblends was investigated by differential scanning calorimetry (DSC).Interestingly,we found that the fractionated crystallization behavior of HDPE was molecular weight dependent.At a fixed composition,HDPE with lower molecular weight showed more obvious fractionated crystallization behavior than HDPE with higher molecular weight.This was ascribed to a finer dispersion of HDPE with lower molecular weight,as evidenced by SEM observations.The fractionated crystallization behavior of HDPE in the blends became less obvious with increasing of its content,due to a change of phase morphology from droplet to co-continuous structure.Correspondingly,a change of tensile toughness of the blends from brittle to ductile mode was observed.

  6. Cultivos de alta densidad celular por retención interna: aplicación a la fermentación continua de etanol High cell density cultures produced by internal retention: application in continuous ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Godoy Rubén Darío

    2004-12-01

    Full Text Available El etanol ha generado gran interés por su potencial como combustible alternativo. No obstante, para que este producto sea competitivo económicamente, es necesario desarrollar procesos de fermentación que incrementen la baja productividad volumétrica lograda en cultivos convencionales (por lote o continuo, por medio de técnicas que permitan altas concentraciones celulares y reduzcan la inhibición por producto. Uno de los métodos empleados frecuentemente involucra la recirculación celular; por ello, en este trabajo se desarrolló un reactor de membrana incorporando un módulo de filtración, con unidades tubulares de 5 u,m en acero inoxidable, dentro de un fermentador de tanque agitado de 3L, para investigar su aplicación en la producción continua de etanol. Los efectos de la concentración celular y la caída de presión transmembranal sobre el flux de permeado fueron evaluados para probar el desempeño del módulo de filtración. Previa selección de las condiciones de fermentación (30 °C, 1,25 -1,75 vvm, pH 4,5, el sistema con retención celular interna fue operado en el cultivo continuo de Saccharomyces cerevisiae a partir de sacarosa. La permeabilidad de las unidades filtrantes fue mantenida mediante la aplicación de pulsos de aire. Más del 97% de las células cultivadas fueron retenidas en el fermentador, alcanzándose una concentración celular de 51 g/L y una productividad promedio de etanol, en el cultivo con retención celular, de 8,51 g/L.h, la cual fue dos veces mayor a la que se obtiene en un cultivo continuo convencional. Palabras clave: reactor de membrana, Saccharomyces cerevisiae, fermentación alcohólica, recirculación celular.Ethanol has provoked great interest due to its potential as an alternative fuel. Nevertheless, fermentation processes must be developed by increasing the low volumetric productivity achieved in conventional cultures (batch or continuous to make this product become economically competitive

  7. High density of defoliated tomato plants in protected cultivation and its effects on development of trusses and fruits Alta densidade com desfolhamento de plantas de tomateiro em cultivo protegido e seus efeitos sobre o desenvolvimento de inflorescências e frutos

    Directory of Open Access Journals (Sweden)

    Miguel A. Sandri

    2002-09-01

    ground area seems to be the upper limit in maximizing the number of set fruits of this crop.O número de frutos em plantas de tomateiro cultivadas em alta densidade e com índice de área foliar similar mantido através de desfolhamento foi determinado em três condições ambientais, no interior de túneis de polietileno. O experimento 1 foi conduzido no outono, com radiação solar média recebida pela cultura de 8,0 MJ m-2 dia-1 e temperatura média exterior de 18,1ºC. Os experimentos 2 e 3 foram conduzidos na primavera, com temperatura média exterior de 19,7ºC. No experimento 2, a radiação solar média recebida pela cultura foi de 12,4 MJ m-2 dia-1, enquanto no experimento 3 foi reduzida para 5,9 MJ m-2 dia-1 por meio de uma tela com 52% de sombreamento. As plantas foram cultivadas em sacolas, com 1,0 m entre fileiras e 0,3 m entre sacolas, enchidas com 5,5 L de substrato comercial. Nutrientes e água foram fornecidos via solução nutritiva, de forma a repor os volumes perdidos pela transpiração. Os tratamentos consistiram de uma (T1, duas (T2 e três (T3 plantas por sacola, correspondendo a densidades de 3,3; 6,7 e 10 plantas m-2, respectivamente. Em T1, três folhas por simpódio foram mantidas, com uma proporção de 3:1 entre o número de folhas e de inflorescências, em cada simpódio. Em T2, duas e uma folha foram mantidas respectivamente em dois simpódios consecutivos, alternativamente em ambas as plantas da sacola. A relação entre o número de folhas e de inflorescências foi de 3:2. Em T3, com três plantas por sacola, somente uma folha por simpódio foi mantida, com uma relação de 3:3. Em todos os experimentos, o número de inflorescências por unidade de área em T2 e T3 foi duas e três vezes maior que em T1, respectivamente. O número de frutos fixados por área de solo foi menor em T1 e similar em T2 e T3 no primeiro experimento, enquanto no segundo e terceiro experimentos valores similares foram observados entre os tratamentos. Os

  8. Humidity Sensing Properties of Pre-irradiation Grafted HDPE Membranes

    Institute of Scientific and Technical Information of China (English)

    Zheng Jiao; Qun Fu; Xiang Geng; Zhen Li; Haijian Zhong

    2006-01-01

    Grafted high density polyethylene (HDPE) films have been prepared by grafting sodium styrene sulfonate (SSS) and acrylic acid (AA) onto HDPE using preirradiation method. The structure and surface morphology of both grafted and ungrafted HDPE films were observed by FTIR spectroscopy and scanning electron microscope (SEM), respectively. The humidity sensing properties of grafted HDPE films were investigated. The results show that the impedance of the film decreases with increasing of relative humidity (RH). The films display high sensitivity with nearly three orders of magnitude change in the resistance during the relative humidity variation from 5% to 98%. Grafted HDPE films exhibit excellent properties as humidity sensors.

  9. 77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

    Science.gov (United States)

    2012-05-18

    ... Energy Regulatory Commission Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC... Practice and Procedure, 18 CFR 385.207, Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind... to firm transmission rights to the capacity of three transmission lines to be constructed by Alta...

  10. Numerical assessment of the HDPE pipe lifetime

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Zouhar, Michal; Ševčík, Martin; Knésl, Zdeněk; Nezbedová, E.

    Merseburg : Polymer Competence Centre Halle-Merseburg, 2011, s. 153-159. ISBN 978-3-86829-400-2. [13. Tagung Problemseminar Deformation und Bruchverhalten von Kunstoffen. Merseburg (DE), 29.06.2011-01.07.2011] R&D Projects: GA ČR GA106/09/0279; GA ČR GC101/09/J027 Institutional research plan: CEZ:AV0Z20410507 Keywords : HDPE pipe * lifetime * fracture mechanics Subject RIV: JL - Materials Fatigue, Friction Mechanics

  11. Concentração plasmática de colesterol total e lipoproteína de alta densidade em novilhas mestiças doadoras de embriões tratadas com somatotropina bovina recombinante Total plasma cholesterol and high-density lipoprotein levels in crossbred heifer embryo donors treated with bovine recombinant somatotropin

    Directory of Open Access Journals (Sweden)

    Á.M. Borges

    2001-10-01

    Full Text Available O objetivo do experimento foi o de estudar as concentrações plasmáticas de colesterol total e lipoproteína de alta densidade (HDL em novilhas mestiças tratadas com somatotropina bovina recombinante (rbST. Coletas de sangue foram feitas durante dois ciclos estrais, normal e superovulado, em 26 fêmeas distribuídas em dois tratamentos: T1 = aplicação de 500mg de rbST no terceiro dia do ciclo estral utilizado para a superovulação e T2 = controle. Análises dos metabólitos sangüíneos foram feitas utilizando-se o método enzimático, cujas concentrações médias plasmáticas de colesterol total e de HDL durante o ciclo estral normal não foram diferentes (P>0,05 entre os dois tratamentos: 87,9 e 25,8mg/dl e 85,9 e 26,7mg/dl para T1 e T2, respectivamente. O ciclo estral utilizado para a superovulação foi dividido em três períodos: P1 = do estro à inseminação artificial (0 ao15º dia, P2 = da inseminação artificial até a coleta de embriões (15º ao 21º dia e P3 = da coleta até o final do período experimental (21º ao 27º dia. As concentrações plasmáticas de colesterol total e HDL no P1 não diferiram entre os tratamentos (P>0,05. Em P2 e P3 houve diferença nas concentrações de HDL e colesterol total entre os dois tratamentos: 29,0 e 88,5mg/dl (T1 e 27,1 e 81,8mg/dl (T2 no P2; e 30,4 e 88,0mg/dl (T1 e 26,6 e 80,5mg/dl (T2 no P3, respectivamente (PThe objective of the experiment was to study the total cholesterol and high-density lipoprotein (HDL levels in crossbred heifers treated with bovine recombinant somatotropina (rbST. Blood samples were collected for two estrous cycles, normal and superovulated, from 26 animals randomly distributed into two treatments: T1 - injected with 500mg rbST on day 3 of estrous cycle and T2 - control. The lipidic metabolite levels were determined by an enzymatic method, and plasma levels of total cholesterol and HDL in normal estrous cycle did not differ (P>0.05 between treatments: 87

  12. TOTAL CHOLESTEROL, HIGH DENSITY LIPOPROTEINS (HDL AND CORTISOL PLASMA LEVELS, AND THEIR BIORHYTMICITY, IN 24 HOURS, THROUGHOUT YEAR, IN IDEAL-POLWARTH RAMS NÍVEIS PLASMÁTICOS DE COLESTEROL TOTAL, LIPOPROTEÍNAS DE ALTA DENSIDADE (HDL E CORTISOL, E SUA BIORRITMICIDADE, EM CARNEIROS IDEAL-POLWARTH

    Directory of Open Access Journals (Sweden)

    Alcides de Amorim Ramos

    2006-12-01

    Full Text Available To evaluate the mean plasma concentrations of total cholesterol (TC, high density lipoproteins (HDL and cortisol, blood samples were collected of five Ideal-Polwarth rams, maintained at 22?53’S latitude, in semi-confinement, every two months throughout the year, by 24h period, with 2-hour intervals between colects. The TC, changed 40.70?1,11mg/dL (April and 61.48?1,11mg/dL (December, between months, while HDL changed 22.16?0.23mg/dL (December as 33.40?0.23mg/dL (February, but not make evident a circannual rhythm in this levels. The TC presented the lowest value at 16:30h (50.40?1.57mg/dL and the highest value at 8:30h collect (54.67?1.57mg/dL; the HDL lowest level was at 10:30h (27.04?0.33mg/dL and the highest level also at 8:30h collect (28.49?0.33mg/dL, however without permit circadian rhythm determination in your plasma concentrations. Similarly, the cortisol plasma concentrations, between collect months, presents variable, however without demonstrate circadian rhythm in this hormone secretion. In relation to different collection’s moments, throughout months, it wasn’t possible to define, by statistical analysis, a circadian rhythm of cortisol secretion. KEY WORDS: Ovine, adrenal hormone, biochemistry metabolites, circadian rhythm. Visando avaliar as concentrações médias de colesterol total (CT, lipoproteínas de alta densidade (HDL e cortisol plasmáticos, foram colhidas amostras de sangue de cinco carneiros Ideal-Polwarth, alocados em latitude 22°53’S, em regime de semiconfinamento, a cada dois meses, ao longo de um ano, com as colheitas em um período de 24 horas, e intervalos de duas horas entre elas. O CT oscilou entre 40,70±1,11mg/dL (abril e 61,48±1,11mg/dL (dezembro, entre os meses, enquanto HDL variou de 22,16±0,23mg/dL (dezembro a 33,40±0,23mg/dL (fevereiro, mas não evidenciando um ritmo circanual em seus níveis. O CT apresentou seu valor mínimo na colheita das 16h30min (50,40±1,57mg/dL e o máximo às 8h30min

  13. Scoping study. High density polyethylene (HDPE) in salstone service

    Energy Technology Data Exchange (ETDEWEB)

    Phifer, Mark A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2005-02-18

    An evaluation of the use of high density polyethylene (HDPE) geomembranes in Saltstone service has been conducted due to the potential benefits that could be derived from such usage. HDPE is one of the simplest hydrocarbon polymers and one of the most common polymers utilized in the production of geomembranes, which means that its costs are relatively low. Additionally, HDPE geomembranes have an extremely low permeability and an extremely low water vapor diffusional flux, which means that it is a good barrier to contaminant transport. The primary consideration in association with HDPE geomembranes in Saltstone service is the potential impact of Saltstone on the degradation of the HDPE geomembranes. Therefore, the evaluation documented herein has primarily focused upon the potential HDPE degradation in Saltstone service.

  14. Uniaxial Fatigue of HDPE-100 Pipe. Experimental Analysis

    OpenAIRE

    Djebli, A.; A. Aid; M. Bendouba; Talha, A.; Benseddiq, N.; M. Benguediab; S. Zengah

    2014-01-01

    In this paper, an experimental analysis for determining the fatigue strength of PE-100, one of the most used High Density Polyethylene (HDPE) materials for pipes, under cyclic axial loadings is presented. HDPE is a thermoplastic material used for piping systems, such as natural gas distribution systems, sewer systems and cold water systems, which provides a good alternative to metals such as cast iron or carbon steel. One of the causes for failures of HDPE pipes is fatigue which is the result...

  15. Efecto de la densidad en el crecimiento de juveniles tempranos de Cherax quadricarinatus (Decapoda: Parastacidae

    Directory of Open Access Journals (Sweden)

    M. C. Gallo-García

    2012-01-01

    Full Text Available En un estudio de cuatro semanas, se evaluó el efecto de tres densidades (134, 178, 223 org/ m2 sobre el crecimiento y supervivencia de juveniles tempranos (0.05 ± 0.02 g de Cherax quadricarinatus cultivados en un sistema de recirculación. Se alcanzaron pesos húmedos de 0.62 a 0.64 g, con tallas de 30.59 a 31.11 mm de longitud total y una supervivencia promedio final de 68%, sin diferencias significativas en los parámetros productivos de las diferentes densidades (p> 0.05. Los resultados sugieren la posibilidad de obtener buenos rendimientos durante el primer mes de cultivo a densidades tan altas como 223 org/m2 en un sistema de recirculación.

  16. Lifetime prediction of HDPE pipes grade

    Czech Academy of Sciences Publication Activity Database

    Nezbedová, E.; Hutař, Pavel; Ševčík, Martin; Náhlík, Luboš; Knésl, Zdeněk

    Vol. 18. Berlin : Deutscher Verband fur Materialforschung und prufung e.V, 2010 - (Klingbeil, D.; Vormwald, M.; Eulitz, G.), s. 1-9 ISBN 978-3-00-031802-3. [18th European Conference on Fracture. Dresden (DE), 30.08.2010-03.09.2010] R&D Projects: GA ČR GA106/08/1409; GA ČR GC101/09/J027; GA ČR GA106/09/0279 Institutional research plan: CEZ:AV0Z20410507 Keywords : HDPE * creep crack * time to rupture curve * PENT test * pipe failure Subject RIV: JL - Materials Fatigue, Friction Mechanics

  17. Filamentos elásticos de elastolefina de alta durabilidad obtenidos a partir de copolímeros de bloque de etileno-octeno de baja densidad mediante la tecnología de polimerización por transferencia de cadena para aplicaciones en indumentaria de uso profesional

    OpenAIRE

    Verdú Blasco, Pau

    2010-01-01

    En la actualidad el mercado carece de prendas elásticas para uso profesional puesto que los elastanos habitualmente utilizados son inestables frente a altas temperaturas y químicos agresivos, e.g. termofijado, mantenimiento de indumentaria industrial etc. Recientemente se han venido utilizado filamentos olefínicos obtenidos a partir de copolímeros al azar de etileno-octeno (Dow XLA fibers producidos por The Dow Chemical Company). Aunque más resistentes a las temperaturas...

  18. MATÉRIA SECA E ABSORÇÃO DE NUTRIENTES EM FUNÇÃO DO ESPAÇAMENTO E DA DENSIDADE DE SEMEADURA EM ARROZ DE TERRA ALTA DRY MATTER AND NUTRIENT UPTAKE OF DRYLAND RICE RELATED TO ROW SPACING AND PLANT POPULATION

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre Costa Crusciol

    1999-01-01

    Full Text Available Foi instalado um experimento em condições de campo, em um Latossolo Vermelho escuro, epi-eutrófico, textura argilosa, em Selvíria-MS, com arroz de sequeiro cv. IAC 201, estudando-se três espaçamentos entre fileiras (30, 40 e 50 cm e três densidades de semeadura (100, 150 e 200 sementes viáveis/m2. Foram avaliadas a produção de matéria seca da parte aérea no momento do florescimento e determinados os teores e quantidades de N, P, K, Ca, Mg e S absorvidos, assim como a eficiência de utilização de nutrientes. A redução do espaçamento entre fileiras aumentou a produção de matéria seca da parte aérea e a quantidade de nutrientes absorvidos. A variação da densidade de semeadura não afetou os parâmetros estudados. A redução do espaçamento entre fileiras proporcionou maior eficiência de utilização do Ca e diminuiu a do N e Mg. Os teores de nutrientes na matéria seca da parte aérea não foram afetados pela variação do espaçamento entre fileiras.A field experiment was conducted in a clayey Dark Red Latosol in Selviria, MS, Brazil, to study the effect of three row spacings (30, 40 and 50 cm and three seed densities (100, 150 and 200 viable seeds/m2 on plant dry matter yield, macronutrient (N, P, K, Ca, Mg and S uptake at flowering, and the nutrient use efficiency. A decrease in row spacing led to an increase in shoot dry matter production and nutrient uptake. There was no effect of plant densities on dry matter or nutrient uptake. The decrease in row spacing allowed a higher Ca use efficiency, but not for N and Mg. The concentration of the macronutrients in the shoots was not affected by spacing.

  19. Uniaxial Fatigue of HDPE-100 Pipe. Experimental Analysis

    Directory of Open Access Journals (Sweden)

    A. Aid

    2014-04-01

    Full Text Available In this paper, an experimental analysis for determining the fatigue strength of PE-100, one of the most used High Density Polyethylene (HDPE materials for pipes, under cyclic axial loadings is presented. HDPE is a thermoplastic material used for piping systems, such as natural gas distribution systems, sewer systems and cold water systems, which provides a good alternative to metals such as cast iron or carbon steel. One of the causes for failures of HDPE pipes is fatigue which is the result of pipes being subjected to cyclic loading, such as internal pressure, weight loads or external loadings on buried pipes, which generate stress in different directions: circumferential, longitudinal and radial. HDPE pipes are fabricated using an extrusion process, which generates anisotropic properties. By testing in the Laboratory a series of identical specimens obtained directly from PE-100 HDPE pipes in longitudinal directions, the relationships between amplitude stress and number of cycles (S-N curve test frequency 2 Hz and stress ratio R = 0.0 are established.

  20. DENSIDADE DE SEMEADURA E PRODUTIVIDADE DO PORONGO

    Directory of Open Access Journals (Sweden)

    Dilson Antônio Bisognin

    1992-04-01

    Full Text Available O trabalho teve como objetivo determinar a melhor densidade de semeadura para a cultura do porongo Lagenaria siceraria (Mol. Standi. Foi realizado um experimento na Universidade Federal de Santa Maria -RS, em 1987-88, com densidades de 2.222; 2.500; 2.666; 3.333 e 4.444 covas/ha, sendo avaliada a produção de frutos industrializáveis (número de frutos/ha e número de frutos/cova. Em outro experimento, instalado em Restinga Seca-RS, em 1988-89, usou-se densidades de 1.111, 2.222, 3.333, 4.444, 5.555 e 6.666 covas/ha, sendo avaliadas a produção de frutos industrializáveis, número de nós na ramificação primária (nós/planta, espessura do casco e volume externo da cuia O delineamento experimental foi blocos ao acaso com quatro repetições e duas plantas por cova, nos dois experimentos. Os resultados de produtividade não mostraram relação com as diferentes densidades estudada?, mas os melhores resultados foram obtidos com densidades que variaram de 3.333 à 5.555 covas por hectare. O número de frutos/cova, nós/planta e a espessura do casco diminuíram à medida que aumentou a densidade de semeadura Em densidades menores a produtividade foi compensada pelo aumento do número de frutos por cova O aumento da densidade de semeadura diminuiu o volume externo da cuia.

  1. Calibrated Pulse-Thermography Procedure for Inspecting HDPE

    Directory of Open Access Journals (Sweden)

    Mohammed A. Omar

    2008-01-01

    Full Text Available This manuscript discusses the application of a pulse-thermography modality to evaluate the integrity of a high-density polyethylene HDPE joint for delamination, in nonintrusive manner. The inspected HDPE structure is a twin-cup shape, molded through extrusion, and the inspection system comprises a high-intensity, short-duration radiation pulse to excite thermal emission; the text calibrates the experiment settings (pulse duration, and detector sampling rate to accommodate HDPE bulks thermal response. The acquired thermal scans are processed through new contrast computation named “self-referencing”, to investigate the joint tensile strength and further map its adhesion interface in real-time. The proposed system (hardware, software combination performance is assessed through an ultrasound C-scan validation and further benchmarked using a standard pulse phase thermography (PPT routine.

  2. Waist circumference is better associated with high density lipoprotein (HDL-c than with body mass index (BMI in adults with metabolic syndrome Circunferencia de la cintura es mejor asociado con lipoproteínas de alta densidad (LAD-C que con el índice de masa corporal (IMC en adultos con síndrome metabólico

    Directory of Open Access Journals (Sweden)

    S. T. Arimura

    2011-12-01

    Full Text Available Background: The measurement of waist circumference (WC is the most prevalent cause of the metabolic syndrome (MS. Objective: The aim of this study was to correlate WC and BMI with high-density lipoprotein (HDL-c levels in patients with MS being consulted by the Family Health Program (PSF, Brazil. Methods: This cross-sectional study was conducted from September to November 2008 with 42 patients (29 women and 13 men from 35 to 77 years. Dietary intake was reported, and biochemical and body composition measures were taken. Results: The HDL-c levels were higher in women when compared to men (48.4 ± 8.1 mg/dL vs. 36.4 ± 7.8 mg/dL. However, the triglycerides (TG/HDL-c ratio and TG concentrations were lower in women (3.8 ± 1.5 and 178.0 ± 57.8 mg/dL, respectively than in men (9.4 ± 8.5 and 471.5 ± 501.5 mg/dL, respectively. Regarding skinfold profile, the triceps was greater in females (37.0 ± 8.4 cm vs. 20.7 ± 10.5 cm. The dietetic profile showed that women had a lower intake of energy, fiber, phosphorus and sodium. The fruits and vegetables intake was diminished in the participants of this study, as less than 60% of the women and 50% of men met the daily recommendations. Approximately 54% of men and 28% of women had a lower intake of dairy products daily. Moreover, the results shows that the WC was negatively correlated to HDL-c (r = -0.41, p 0.06. Conclusion: Our findings showed that WC is a better predictor of changes in HDL-c than BMI.Antecedentes: La medición de la circunferencia de la cintura (CC es la causa más prevalente del síndrome metabólico (SM. Objetivo: el propósito de este estudio fue correlacionar la CC y el IMC con las concentraciones de lipoproteínas de densidad elevada (HDL-c en pacientes con SM vistos en consulta del Programa de salud familiar (PSF, de Brasil. Métodos: Este estudio trasversal se realizó entre septiembre y noviembre de 2008 en 42 pacientes (29 mujeres y 13 hombres de 35 a 77 años. Se registró la

  3. Enhanced mechanical and thermal properties of CNT/HDPE nanocomposite using MMT as secondary filler

    Science.gov (United States)

    Ali Mohsin, M. E.; Arsad, Agus; Fouad, H.; Jawaid, M.; Alothman, Othman Y.

    2014-05-01

    This study explains the influence of secondary filler on the dispersion of carbon nanotube (CNT) reinforced high density polyethylene (HDPE) nanocomposites (CNT/HDPE). In order to understand the mixed-fillers system, Montmorillonite (MMT) was added to CNT/HDPE nanocomposites. It was followed by investigating their effect on the thermal, mechanical and XRD properties of the aforesaid nanocomposite. Incorporation of 3 wt% each of MMT into CNT/HDPE nanocomposite resulted to the increased values for the tensile and flexural strength, as compared to the pure HDPE matrix. The thermal analysis result showed improved thermal stability of the formulated nanocomposites.

  4. Altas capacidades e interdisciplinariedad

    OpenAIRE

    Moreno-García, María José

    2013-01-01

    El presente trabajo fin de grado trata de abordar la importancia de dar una respuesta educativa acorde a las necesidades del alumnado de altas capacidades. Para ello, primeramente, se ha visto necesario definir el término de altas capacidades, analizar sus características, matizar la importancia de su detección temprana, desbancar falsos mitos y conocer la legislación vigente al respecto, para posteriormente elaborar una propuesta de intervención, que se ha llevado a cabo en el Colegio Nelva,...

  5. Mechanical Properties of Palm Fibre Reinforced Recycled HDPE

    Directory of Open Access Journals (Sweden)

    B. Aldousiri

    2013-01-01

    Full Text Available Recently, recycled thermoplastic polymers become an alternative resource for manufacturing industrial products. However, they have low mechanical properties compared to the thermosets. In this paper, an attempt has been made to enhance the mechanical properties of recycled high density polyethylene (HDPE with chopped strand mat (CSM glass fibres as a synthetic reinforcement and with short oil palm fibres as a biodegradable (natural reinforcement. The effects of volume fraction of both synthetic and natural fibres on tensile, compression, hardness, and flexural properties of the HDPE were investigated. The failure mechanism of the composite was studied with the aid of optical microscopy. Tensile properties of the HDPE composites are greatly affected by the weight fraction of both the synthetic and the natural fibres. The higher strength of the composites was exhibited when at higher weight fraction of both natural and syntactic fibres which was about 50 MPa. Date palm fibre showed good interfacial adhesion to the HDPE despite the untreated condition used. On the other hand, treatment of the fibres is recommended for higher tensile performance of the composites.

  6. Influence of blending sequence on the rheological behavior of HDPE/LLDPE/MMT nano composites

    International Nuclear Information System (INIS)

    The blending sequence affects the rheological behavior and the morphology formation of the nanocomposites. In this work, the blending sequences were explored to see its influence in the rheological behavior of HDPE/LLDPE/MMT nanocomposites. The nanocomposites were obtained by melt-intercalation using HDPE-g-MA as a compatibilizer in a torque rheometer (Haake Rheomix 600p at 180 deg C and rotor speed of 80rpm) and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where HDPE and HDPE-g-MA were first reinforced with organoclay and then the HDPE/HDPE-g-MA/organoclay nanocomposite was later blended with LLDPE. (author)

  7. Estonia's Alta buys Lauma lingerie

    Index Scriptorium Estoniae

    2004-01-01

    Eesti investeeringute firma Alta Capital ostis 76,4 protsenti pesutootja Lauma aktsiatest. Tulevikus plaanitakse suunduda Ida- ja Lääne-Euroopa turgudele. Alta Capital omab 79 protsenti Klementi aktsiatest

  8. Densidad y biomasa de macroinvertebrados acuáticos derivantes en una quebrada tropical de montaña (bogotá, colombia)

    OpenAIRE

    2013-01-01

    Se estimó la variación en la densidad de deriva de macroinvertebrados acuáticos y suaporte de materia orgánica en términos de biomasa de diferentes estados inmadurose imagos, en un tramo de una quebrada tropical de montaña ubicada en los cerrosorientales de Bogotá – Colombia y durante eventos de altas y bajas precipitaciones.Se colectó un total de 96 taxones de los cuales el más abundante fue Simulium con194 individuos (abundancia total). La densidad de deriva al igual que el aporte debiomasa...

  9. Operador de densidad. Operadores producto (2009)

    OpenAIRE

    Paniagua, Juan Carlos

    2009-01-01

    Breve introducción al formalismo del operador de densidad y su aplicación a la resonancia magnética nuclear. Se incluye el método de los operadores producto para analizar la evolución de sistemas de espines.

  10. Operador de densidad. Operadores producto (2006)

    OpenAIRE

    Paniagua, Juan Carlos

    2008-01-01

    Breve introducción al formalismo del operador de densidad y su aplicación a la resonancia magnética nuclear. Se incluye el método de los operadores producto para analizar la evolución de sistemas de espines.

  11. Operador de densidad. Operadores producto (2012)

    OpenAIRE

    Paniagua, Juan Carlos

    2012-01-01

    Breve introducción al formalismo del operador de densidad y su aplicación a la resonancia magnética nuclear. Incluye el método de los operadores producto para analizar la evolución de sistemas de espines.

  12. Time-resolved WAXD/SAXS Characterization on the Crystallization of Silica Filled HDPE Nanocomposite

    Science.gov (United States)

    Li, Xiaowei; Burger, Christian; Mao, Yimin; Hsiao, Benjamin

    2012-02-01

    The isothermal crystallization behavior of high density polyethylene/silica (HDPE-SiO2) with different SiO2 loading of 2% and 5%, along with the pure HDPE sample was studied by using the time-resolved wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) techniques. For isothermal crystallization at 120 ^oC, WAXD profiles show HDPE-Si2% has the highest ending crystallinity index, while HDPE-Si5% has the lowest value. Avrami exponent of pure HDPE is about 3.9, while HDPE-Si2% has a value of 3.2 which is typically heterogeneous nucleation behavior due to the addition of silica in HDPE. SAXS patterns show that the silica inside HDPE has mass fractal structure. The mass fractal dimension is determined by using the fitting method and the value is less than 3 for all HDPE-SiO2 samples. The structure of HDPE-SiO2 is sketched based on the obtained results.

  13. Modification of HDPE by γ ray radiation in oxygen atmosphere and blend with PA6

    International Nuclear Information System (INIS)

    A study on the oxidation of high density polyethylene (HDPE) by γ ray irradiation in oxygen atmosphere has been made. The influence of irradiated time on the oxidation has been investigated with the help of Fourier Transform Infrared-Photoacoustics Spectroscopy (FTIR-PAS). Results of FTIR-PAS show after irradiation groups like -C=O, -O-C-O-, O=C-O- were introduced into the HDPE. Although the γ ray has powerful penetrability, the oxidation mainly takes place on the surface of HDPE. after 4 h irradiation in oxygen (dose rate 66 Gy/min.), -C=O is the main group which was introduced into the surface of HDPE. Lengthening the irradiation process makes the pre-produced oxidized section in HDPE surface continue their reactions to yield some oxidation products with the structures of -O-C-O-, O=C-O- and so on. FTIR shows there are reactions or week interaction like hydrogen bond between the irradiated HDPE and PA6 in the binary blends, this is helpful to increase the compatibility of the phase of HDPE and polyamide-6 (PA6) in the blend. Scanning Electron Microscope (SEM) result shows that the interface between HDPE matrix and PA6 domains is much clear and smoother in 0γHDPE/PA6 blends than in 4γHDPE/PA6 and 7γHDPE/PA6 blends. These suggested the miscibility of PA6 and HDPE was improved after HDPE irradiating in oxygen by γ ray radiation

  14. Mechanical Properties of Palm Fibre Reinforced Recycled HDPE

    OpenAIRE

    Aldousiri, B.; M. Alajmi; Shalwan, A.

    2013-01-01

    Recently, recycled thermoplastic polymers become an alternative resource for manufacturing industrial products. However, they have low mechanical properties compared to the thermosets. In this paper, an attempt has been made to enhance the mechanical properties of recycled high density polyethylene (HDPE) with chopped strand mat (CSM) glass fibres as a synthetic reinforcement and with short oil palm fibres as a biodegradable (natural) reinforcement. The effects of volume fraction of both synt...

  15. Análisis del ciclo de vida del reciclado del polietileno de alta densidad

    OpenAIRE

    Garraín Cordero, Daniel; Vidal Nadal, María Rosario; Franco García, Vicente; Martínez Sebastiá, Pilar

    2008-01-01

    Thermoplastics make up roughly 80% of the plastics produced today. There are hundreds of types of them and new variations are being developed. But not all thermoplastics are recyclable in the same proportion. The most commonly recycled thermoplastics are polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC). In this study, real data from the industry is used in the analysis of the environmental impact of plastics recycling by means of the application of the ...

  16. Uropatia Obstrutiva Alta

    OpenAIRE

    Campos Pinheiro, L; Matos Ferreira, A

    1999-01-01

    As lesões obstrutivas do aparelho urinário são muito frequentes. Apresenta-se uma revisão da etiologia e fisiopatologia da uropatia obstrutiva alta. Descreve-se pormenorizadamente a sua clínica e diagnóstico realçando-se os exames complementares mais adequados. Por fim apresentam-se as orientações terapêuticas e o prognóstico das diversas situações englobadas neste capítulo.

  17. de alta frecuencia

    Directory of Open Access Journals (Sweden)

    Juan Carlos Gáquez Abab

    2007-01-01

    Full Text Available Los mercados de consumo de alta frecuencia presentan rasgos particulares en cuanto a la diversidad de estrategias de precio, constantes promociones en precio, publicidad masiva o estrategias de marca que hacen que la identificación de segmentos sea especialmente interesante para la empresa. En el presente trabajo se lleva a cabo un análisis de segmentación sobre datos de panel que pretende identificar cuántos segmentos existen y describir cuál es su comportamiento en relación a variables como el precio o las promociones de ventas.

  18. Study on Melt Grafting of GMA/St onto HDPE and Properties of HDPE/PET Blends Compatibilized by the Graft%HDPE熔融接枝GMA/St及其增容HDPE/PET合金性能的研究

    Institute of Scientific and Technical Information of China (English)

    陆丽浓; 李树材; 秦宗杰; 马伟

    2007-01-01

    利用HAAKE流变仪,采用熔融接枝法分别制备了甲基丙烯酸缩水甘油酯(GMA)、GMA/苯乙烯(St)接枝高密度聚乙烯(HDPE),将所得接枝物HDPE-g-GMA和HDPE-g-(GMA-co-St)作为HDPE/PET共混合金的反应性增容剂,研究了其对体系力学性能和热致形状记忆性能等的影响.结果表明:采用GMA/St双组分单体具有较高的接枝率,生成的接枝物对HDPE/聚对苯二甲酸乙二醇酯(PET)共混合金的增容效果较好;提高了体系的力学性能和热致形状记忆性能,且HDPE-g-(GMA-co-St)含量为5~10 phr时,合金具有较好的综合性能.

  19. MECHANICAL PROPERTIES OF OZONIZED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE

    Institute of Scientific and Technical Information of China (English)

    Mian Zhou; Yi Fu; Wen Xu; Xi Xu

    2005-01-01

    The mechanical properties of ozonized high density polyethylene (HDPE) blended with sericite-tridymitecristobalite (STC) were studied in this paper. The experimental results show that some oxygen containing polar groups are introduced on the molecular chain of HDPE through ozonization, the compatibility between HDPE and STC is thus improved, the mechanical properties of the blend are markedly enhanced. Compared with untreated HDPE/STC (60/40)blend, the yield strength and notched impact strength of ozonized HDPE/STC (60/40) blend are increased from 27.0 MPa to 29.5 MPa and from 2.8 kJ/m2 to 13.3 kJ/m2, respectively, the notched impact strength is close to that of HDPE (13.6 kJ/m2),the yield strength is in excess of 3.9 MPa of that of HDPE. The yield strength and notched impact strength will be further increased to 30.7 MPa and 32.4 kJ/m2 in case the ozonized HDPE is blended with STC pretreated with silane coupling agent.

  20. A burn-down prevention method of HDPE insulator

    International Nuclear Information System (INIS)

    Covered conductors have been used on high as well as low voltage overhead distribution lines for preventing brush contact and short circuit failure between conductors. Conductor bum-down has frequently occurred on covered conductors, but bum-down seldom occurs on bare conductors. Therefore it has become a problem. Burn-down happens because a high electric field region occurs around covered conductors. There are some factors for that. We noticed some factors and identified a bum-down prevention method of HDPE Insulator using the finite element method electric field simulation. In this paper, we propose this method because useful results were obtained. (Author)

  1. Biocompatibility and preliminary clinical application of HA/HDPE nanocomposites synthetic auditory ossicle

    Institute of Scientific and Technical Information of China (English)

    ZHU Shai-hong; WANG Guo-hui; ZHAO Yan-zhong; QI You-fei; ZHOU Ke-chao; HUANG Su-ping; LI Zhi-you; HUANG Bai-yun

    2006-01-01

    The biocompatibility of the hydroxyapatite/high density polyethtlene(HA/HDPE) nanocomposites synthetic auditory ossicle was evaluated, the percentage of S-period cells was detected by flow cytometry after L929 incubated with extraction of the HA/HDPE nanocomposites, titanium materials of clinical application as the control. Both of them were implanted in the animals and the histopathological evaluations were carried out, and the preliminary clinical trials about HA/HDPE nanocomposites synthetic auditory ossicles were also carried out. The statistical analysis show that there are no statistically significant differences between HA/HDPE test groups and control groups (P>0.05), which demonstrates that the HA/HDPE nanocomposites synthetic auditory ossicle has a good biocompatibility and clinical application outlook.

  2. Tensile strength of ramie yarn (spinning by machine)/HDPE thermoplastic matrix composites

    Science.gov (United States)

    Banowati, Lies; Hadi, Bambang K.; Suratman, Rochim; Faza, Aulia

    2016-03-01

    Technological developments should be trooped to prevent a gap between technology and environmental sustainability, then it needs to be developed "Green technology". In this research is making of green composites which use natural fiber ramie as reinforcement. Whereas the matrix used was HDPE (High Density Polyethylene) thermoplastic polymer which could be recycled and had a good formability and flexibility. The ramie yarns and fibers for unidirectional (0°) direction respectively were mixed with HDPE powder and processed using hot compression molding. The surface morphology was observed by SEM (Scanning Electrone Microscopy). Results showed that both tensile strength of the ramie fiber/HDPE composites increased in comparison with the ramie yarn (spinning by machine)/HDPE composites. However, the ramie yarn (spinning by machine)/HDPE composites have a good producibility for wider application. Analysis of the test results using the Weibull distribution as approaches to modeling the reliability of the specimens.

  3. Study on Properties of HDPE/Nano-CaCO3 Composite%HDPE/nano-CaCO3复合材料性能研究

    Institute of Scientific and Technical Information of China (English)

    崔文广; 高岩磊; 刘会茹; 郧海丽

    2012-01-01

    HDPE/nano-CaCO3 composite was prepared by melt blending. The effect of the nano-CaCO3 content on mechanical property of the HDPE/nano-CaCO 3 composite was studied. The dispersion of the nano-CaCOj in HDPE matrix was analyzed by SEM. The results showed that the impact strength and tensile strength of the HDPE/namrCaCO3 composite both increased with the namrCaCO3 content, and then decreased with the nano-CaCOj content, but the flexural modulus of the HDPE/namrCaCO3 composite evidently increased with the nano-CaCO3 content. The dispersion of the nano-CaCO3 in HDPE matrix gradually became bad.%采用熔融共混法制备出了高密度聚乙烯( HDPE)/纳米碳酸钙(nano-CaCO3)复合材料.研究了nano-CaCO3的加入量对复合材料力学性能的影响,利用扫描电镜(SEM)分析了nano-CaCO3在HDPE基体中的分散性.结果表明,随着nano-CaCO3用量的增加,HDPE/nano-CaCO3复合材料的冲击强度和拉伸强度均呈现出先增加后降低的趋势,而弯曲模量呈增加趋势;随着用量的增加,nano-CaCO3在HDPE基体中的分散性逐渐变差.

  4. Hinting en pantallas de alta resolución

    OpenAIRE

    Rodriguez, D

    2012-01-01

    Las pantallas de alta resolución no son algo nuevo —hay prototipos documentados ya en los años ochenta— pero al parecer ha llegado el momento de implantar esta tecnología: en junio de 2010 Steve Jobs presentó el iPhone 4 con la pantalla Retina como principal novedad: una superfície de 3,5 pulgadas con una densidad de 336 píxeles por pulgada. El ojo humano es incapaz de distinguir los píxeles en una imagen de esa resolución, por lo que el equipo directivo de Apple decidió bautizarla como Retin...

  5. Mechanical properties of micro-injected HDPE composites

    Science.gov (United States)

    Bongiorno, A.; Pagano, C.; Agnelli, S.; Baldi, F.; Fassi, I.

    2016-03-01

    Micro-injection moulding is one of the key manufacturing technologies for the mass production of high value polymeric miniaturized-components. However, this process is not just a straightforward down scaling of the conventional injection moulding technique. Indeed, during the micro-injection the polymer melt is forced to flow at high strain rates through very small channels in non-isothermal conditions, and this can lead to complex microstructures and to parts with unexpected performances. In this work, the relationships among the processing conditions, the mechanical properties and the microstructural characteristics of miniaturized specimens obtained by injection moulding were investigated. Two model systems were considered with the same filler content of 15% wt. (HDPE-talc and HDPE-glass beads), representative of two different types of micro-composites: containing lamellar and spherical micro-particles, respectively. The attention was focused on the influence of the filler type and the process conditions on the mechanical behaviour, examined by uniaxial tensile tests and dynamic-mechanical analyses, and on the morphological characteristics of the specimens, examined by microscopy analyses. The results highlight that mechanical response of the miniaturized specimens is significantly affected by both the filler and the process conditions that can have an influence on the polymer microstructure. Lamellar composites showed the best performance due to the orientation of the talc particles during the micro-injection process, while, different morphologies of the skin/core transition region in dependence on the process temperatures were observable.

  6. THE EFFECT OF MATRIX TOUGHNESS ON THE BRITTLE-DUCTILE TRANSITION OF HDPE/CaCO3 BLENDS

    Institute of Scientific and Technical Information of China (English)

    FU Qiang; ZHANG Yulin; WANG Guiheng

    1994-01-01

    The effects of HDPE matrix toughness on the brittle-ductile transition of HDPE/CaCO3 blends are investigated. Not all HDPE can be toughened by CaCO3 particles. The ability of the matrix to yield plays a fundamental role in determing whether HDPE can be toughened or not.There exists a critical matrix toughness (Isc≈45J/m) below which HDPE can not be toughened observably by CaCO3 particle at given average size, and above which the critical matrix ligament thickness (τc) is proportional to matrix impact strength.

  7. Influence of blending sequence on the rheological behavior of HDPE/LLDPE/MMT nano composites; Influencia da sequencia de mistura no comportamento reologico de nanocompositos HDPE/LLDPE/MMT

    Energy Technology Data Exchange (ETDEWEB)

    Passador, F.R.; Pessan, L.A., E-mail: fabiopassador@gmail.co [Universidade Federal de Sao Carlos (DEMA/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais; Ruvolo Filho, A. [Universidade Federal de Sao Carlos (PPGCEM/UFSCAR), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    The blending sequence affects the rheological behavior and the morphology formation of the nanocomposites. In this work, the blending sequences were explored to see its influence in the rheological behavior of HDPE/LLDPE/MMT nanocomposites. The nanocomposites were obtained by melt-intercalation using HDPE-g-MA as a compatibilizer in a torque rheometer (Haake Rheomix 600p at 180 deg C and rotor speed of 80rpm) and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where HDPE and HDPE-g-MA were first reinforced with organoclay and then the HDPE/HDPE-g-MA/organoclay nanocomposite was later blended with LLDPE. (author)

  8. A STUDY ON MECHANICAL PROPERTIES OF γ-RAY IRRADIATED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The effect of γ-ray irradiation on the mechanical properties of high density polyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The experimental results show that γ-ray irradiation can improve the affinity between HDPE and STC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blend are increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress and impact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.

  9. INFLUENCE OF LIGNIN CONTENT ON PHOTODEGRADATION IN WOOD/HDPE COMPOSITES UNDER UV WEATHERING

    Directory of Open Access Journals (Sweden)

    Narongrit Sombatsompop

    2011-11-01

    Full Text Available The aim of this work was to examine the influence the lignin component of wood on the photodegradation of high-density polyethylene (HDPE in wood/HDPE (WPE composites. The neat HDPE and wood/HDPE composites were prepared using a twin screw extruder followed by an injection moulder. The lignin content was varied from 0 to 29 %wt. of wood by the addition of delignified wood pulp into wood flour. The results suggested that the photodegradation of HDPE in WPE composites was accelerated by the presence of lignin; the chromophoric groups in the lignin enhanced UV adsorption onto the WPE composite surface. The carbonyl and vinyl indices, color, percentage crystallinity, and the melting temperature increased when the lignin contents were increased. The color fading in WPE composites resulted from photobleaching of lignin. In addition, the presence of lignin led to the development ofl cracks in WPE composites, especially at high lignin contents. For the effect of UV weathering time, the carbonyl and vinyl indices, discoloration, and percentage crystallinity increased as a function of UV weathering times, whereas the melting temperature of HDPE in both neat HDPE and WPE composites and water absorption of specimens decreased; the wood index in WPE composites increased during the initial UV weathering times and then decreased at 720 h weathering time.

  10. Data characterizing tensile behavior of cenosphere/HDPE syntactic foam.

    Science.gov (United States)

    Kumar, B R Bharath; Doddamani, Mrityunjay; Zeltmann, Steven E; Gupta, Nikhil; Ramakrishna, Seeram

    2016-03-01

    The data set presented is related to the tensile behavior of cenosphere reinforced high density polyethylene syntactic foam composites "Processing of cenosphere/HDPE syntactic foams using an industrial scale polymer injection molding machine" (Bharath et al., 2016) [1]. The focus of the work is on determining the feasibility of using an industrial scale polymer injection molding (PIM) machine for fabricating syntactic foams. The fabricated syntactic foams are investigated for microstructure and tensile properties. The data presented in this article is related to optimization of the PIM process for syntactic foam manufacture, equations and procedures to develop theoretical estimates for properties of cenospheres, and microstructure of syntactic foams before and after failure. Included dataset contains values obtained from the theoretical model. PMID:26937472

  11. Effect of compatibilizer on impact and morphological analysis of recycled HDPE/PET blends

    International Nuclear Information System (INIS)

    Blends based on recycled high density polyethylene (rHDPE) and recycled polyethylene terephthalate (rPET) were prepared using a corotating twin screw extruder. PET and HDPE are incompatible polymers and their blends showed poor properties. Compatibilization is a step to obtain blends with good mechanical properties and in this work, ethylene glycidyl methacrylate copolymer (E-GMA) was used as a compatibilizing agent. The effect of blends based on rHDPE and rPET with and without a compatibilizer, E-GMA were examined. From the studies clearly showed that the addition of 5% E-GMA increased the impact strength. SEM analysis of rHDPE/rPET blends confirmed the morphological interaction and improved interfacial bonding between two phases

  12. Effect of compatibilizer on impact and morphological analysis of recycled HDPE/PET blends

    Science.gov (United States)

    Salleh, Mohd Nazry; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Chen, Ruey Shan

    2013-11-01

    Blends based on recycled high density polyethylene (rHDPE) and recycled polyethylene terephthalate (rPET) were prepared using a corotating twin screw extruder. PET and HDPE are incompatible polymers and their blends showed poor properties. Compatibilization is a step to obtain blends with good mechanical properties and in this work, ethylene glycidyl methacrylate copolymer (E-GMA) was used as a compatibilizing agent. The effect of blends based on rHDPE and rPET with and without a compatibilizer, E-GMA were examined. From the studies clearly showed that the addition of 5% E-GMA increased the impact strength. SEM analysis of rHDPE/rPET blends confirmed the morphological interaction and improved interfacial bonding between two phases.

  13. Effect of compatibilizer on impact and morphological analysis of recycled HDPE/PET blends

    Energy Technology Data Exchange (ETDEWEB)

    Salleh, Mohd Nazry [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia and School of Materials Engineering, Universiti Malaysia Perlis, 02600 Jejawi, Perlis (Malaysia); Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Chen, Ruey Shan [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    Blends based on recycled high density polyethylene (rHDPE) and recycled polyethylene terephthalate (rPET) were prepared using a corotating twin screw extruder. PET and HDPE are incompatible polymers and their blends showed poor properties. Compatibilization is a step to obtain blends with good mechanical properties and in this work, ethylene glycidyl methacrylate copolymer (E-GMA) was used as a compatibilizing agent. The effect of blends based on rHDPE and rPET with and without a compatibilizer, E-GMA were examined. From the studies clearly showed that the addition of 5% E-GMA increased the impact strength. SEM analysis of rHDPE/rPET blends confirmed the morphological interaction and improved interfacial bonding between two phases.

  14. Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE

    Directory of Open Access Journals (Sweden)

    S. S. Cota

    2007-06-01

    Full Text Available This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates.

  15. Isothermal Crystallization Kinetics of HDPE/HA Compounds Irradiated with Sterilization Doses of Gamma Rays

    International Nuclear Information System (INIS)

    The objective of this work was to study the isothermal crystallization of High Density Polyethylene/Hydroxyapatite nanocomposites, with 2 and 5 ppc of HA, irradiated with 25 kGy (sterilization dose) of γ-Ray from a 60Co source, at a rate of 4.8 kGy/h in air and at room temperature. The selected crystallization temperatures were 118, 117, 116 and 115 degree. The crystallization kinetics was analyzed using the Avrami's model whose parameters were optimized using a non-linear regression technique. Regression results show that the Avrami exponent varies between 1.8 and 1.5, meaning that the spherulitic growth is mainly two dimensional. Values for specific crystallization constant 'k' were found to be higher for HDPE/HA compounds than for pure HDPE, clearly indicating the presence of an HA nucleation effect. It was also observed that values for the specific crystallization constant 'k' decreases with increasing temperatures, being this effect more noticeable for HDPE/HA compounds than for pure HDPE. Regarding to irradiated samples, their 'k' values were found to be lower than those for non irradiated samples, the difference getting more significant with decreasing crystallization temperature. Simulation of experimental data with the Avrami's model show a clear influence of the crystallization temperature, the HA content in the sample and the amount of applied radiation. It was also observed that the Avrami model correlates satisfactorily experimental data for not irradiated samples of pure HDPE and HDPE/HA compounds at the highest crystallization (Tc). However, as the crystallization temperature decreases, the values simulated with the Avrami model increasingly deviate from experimental data, specifically at the highest values of the relative crystallinity. This effect is even stronger on irradiated samples of HDPE and HDPE/HA compounds

  16. Study of the Mechanical and Morphology Properties of Recycled HDPE Composite Using Rice Husk Filler

    OpenAIRE

    Jia Ying Tong; Nishata Royan Rajendran Royan; Yong Chuen Ng; Mohd Hafizuddin Ab Ghani; Sahrim Ahmad

    2014-01-01

    WPCs are being used in a large number of applications in the automotive, construction, electronic, and aerospace industries. There are an increasing number of research studies and developments in WPC technology involving rice husk as fillers. This study investigated the effects of different compositions of rice husk (RH) filler on the mechanical and morphological properties of recycled HDPE (rHDPE) composite. The composites were prepared with five different loading contents of RH fibers (0, 1...

  17. Influence of wood species on properties of injection mould natural flour-HDPE composites

    Science.gov (United States)

    Ratanawilai, Thanate; Leeyoa, Massalan; Tiptong, Yoawanat

    2016-05-01

    Four combinations of wood flour, HDPE, and maleic anhydride (MA) include; (1) rubberwood:HDPE (30:70), (2) rubberwood: HDPE:MA (30:67:3), (3) palm oil:HDPE (30:70), and (4) palm oil:HDPE:MA (30:67:3) were studied. The injection moulding machine was used to produce wood plastic composites (WPCs). Maleic anhydride is an ingredient in bonding agents used to manufacture wood plastic composites. Extrusion molding process was conducted to prefabricate WPCs. Consequently, the effect of temperature and pressure ranging from 180, 190, 200°C and 2300, 2400, 2500 bar on injection molding was evaluated. Mechanical properties were tested including flexural testing and tensile testing according to ASTM D790 and D638, respectively. Hardness testing according to ASTM D2240 and scanning electron microscope (SEM) were also performed. Five replications were done on each test. The result showed that rubberwood:HDPE (30:70) gave a highest strength. The values of ultimate tensile strength, flexural strength, and hardness are 24.9 MPa, 33.3 MPa and 67.2 shore D, respectively. Finally, the uniform distribution of particle in WPCs, examined through SEM was achieved.

  18. A study on thermal behaviour of HDPE/CaCO3 nanocomposites

    Directory of Open Access Journals (Sweden)

    S.M. Zebarjad

    2006-04-01

    Full Text Available Purpose: In order to improve physical and mechanical properties of high density polyethylene (HDPE addition of filler, rigid particles and even elastomer to HDPE is very common. One of the most important filler which is added to it is nano size calcium carbonate (CaCO3. To avoid agglomeration of nano size calcium carbonate addition of fatty acids such as stearic acid is very common.Design/methodology/approach: In the current study, nanocomposites with 10vol% nano size calcium carbonate were prepared. To investigate the role of stearic acid on nanocomposite behaviour, nanoparticles were coated at different stearic acid content. Thermal behaviour of high density polyethylene and its nanocomposites reinforced with both uncoated and coated calcium carbonate were investigated. For this purpose differential scanning calorimetry (DSC test was used. Findings: The results of DSC test showed that addition of 10vol% calcium carbonate to HDPE causes a slightly rise in its melting point but stearic acid content has no significant effect on the melting temperature of HDPE nanocomposites.Research limitations/implications: : Agglomeration of nanosized calcium carbonate during sample preparation was the major research limitation.Originality/value: Crystallization temperature of HDPE with addition of 10vol% calcium carbonate increases, while addition of stearic acid causes to decrease it. Both stearic acid content and 10vol% calcium carbonate have no significant effect on crystallinity index of HDPE.

  19. DENSIDAD POBLACIONAL Y ESTRUCTURA DE GRUPO DE Ateles hybridus brunneus (PRIMATES: ATELIDAE) EN UN FRAGMENTO DE BOSQUE AISLADO EN EL SURORIENTE DE ANTIOQUIA, COLOMBIA

    OpenAIRE

    Néstor J. Roncancio; Lina M. García; Amilvia Acosta

    2010-01-01

    Se encontró un grupo de Ateles hybridus brunneus en un fragmento de bosque aislado de 21 ha, con una densidad de 39 individuos/km2 (IC95% = 21.3-72.9). Esta área es la más pequeña donde se ha estimado alta densidad para Ateles. El grupo de A. h. brunneus estuvo compuesto por nueve individuos, grupo más pequeño que el registrado en otras investigaciones. Ateles tiene un sistema social fisión-fusión, donde los grupos se dividen en subgrupos. El tamaño promedio de subgrupo fue de cuatro individu...

  20. Transporte de juvenis de curimbatá Prochilodus lineatus em diferentes densidades =Transportation of curimbata Prochilodus lineatus juveniles in different densities

    OpenAIRE

    André Fernando Nascimento Gonçalves; Leonardo Susumu Takahashi; Elisabeth Criscuolo Urbinati; Jaqueline Dalbello Biller; João Batista Kochenborger Fernandes

    2010-01-01

    Neste estudo foi avaliado o efeito do transporte de curimbatá Prochilodus lineatus, em três densidades (100, 150 e 250 g L-1), sobre a sobrevivência e variáveis metabólicas, iônicas e hematológicas (série vermelha). Juvenis de curimbatá foram transportados em sacos plásticos durante 6h e amostrados antes da embalagem, imediatamente após a chegada, 24 e 96h após o transporte. Os peixes transportados na densidade mais alta apresentaram maior mortalidade durante o período de recuperação. As vari...

  1. Ajuste do modelo de Reineke para estimativa da linha de máxima densidade na Floresta Estacional Decidual no Rio Grande do Sul

    Directory of Open Access Journals (Sweden)

    Evandro Alcir Meyer

    2013-08-01

    Full Text Available O objetivo deste trabalho foi estudar a relação entre a densidade de árvores por hectare e o diâmetro médio de uma Floresta Estacional Decidual, bem como ajustar o modelo Reineke para descrever esse comportamento, comparando o desempenho de diferentes métodos. A área de estudo localiza-se no Município de Silveira Martins, na região central do Rio Grande do Sul, e encontra-se em estágio inicial de sucessão, após o uso agrícola. As informações referentes ao número de árvores por hectare e ao diâmetro médio foram obtidas por meio do método de densidade pontual proposto por Spurr. As amostras foram tomadas nos estágios iniciais de uma floresta secundária, escolhendo-se áreas onde predominava o camboatá-vermelho (Cupania vernalis. Como as florestas naturais apresentam espaçamento irregular, a densidade é bastante variável. Assim, para selecionar apenas parcelas em alta densidade, foram escolhidas áreas onde se verificava a ocorrência de indivíduos mortos. Foram testados diferentes métodos para estimar o limite superior da linha de autodesbaste: a análise de regressão (para todos os dados e densidade relativa maior que 60%, corrigindo o intercepto para que os resíduos fossem negativos; o ajuste manual; o de densidade relativa (DR>90%; e a análise de fronteira estocástica. O método que melhor estimou a máxima densidade foi a análise de regressão com dados de no mínimo 60% da densidade máxima, obtendo-se um coeficiente angular de -1,563 para o modelo de Reineke. Não houve diferença significativa entre as potências fornecidas pelos diferentes métodos.

  2. Modulation of Protein Adsorption and Cell Proliferation on Polyethylene Immobilized Graphene Oxide Reinforced HDPE Bionanocomposites.

    Science.gov (United States)

    Upadhyay, Rahul; Naskar, Sharmistha; Bhaskar, Nitu; Bose, Suryasarathi; Basu, Bikramjit

    2016-05-18

    The uniform dispersion of nanoparticles in a polymer matrix, together with an enhancement of interfacial adhesion is indispensable toward achieving better mechanical properties in the nanocomposites. In the context to biomedical applications, the type and amount of nanoparticles can potentially influence the biocompatibility. To address these issues, we prepared high-density polyethylene (HDPE) based composites reinforced with graphene oxide (GO) by melt mixing followed by compression molding. In an attempt to tailor the dispersion and to improve the interfacial adhesion, we immobilized polyethylene (PE) onto GO sheets by nucleophilic addition-elimination reaction. A good combination of yield strength (ca. 20 MPa), elastic modulus (ca. 600 MPa), and an outstanding elongation at failure (ca. 70%) were recorded with 3 wt % polyethylene grafted graphene oxide (PE-g-GO) reinforced HDPE composites. Considering the relevance of protein adsorption as a biophysical precursor to cell adhesion, the protein adsorption isotherms of bovine serum albumin (BSA) were determined to realize three times higher equilibrium constant (Keq) for PE-g-GO-reinforced HDPE composites as compared to GO-reinforced composites. To assess the cytocompatibility, we grew osteoblast cell line (MC3T3) and human mesenchymal stem cells (hMSCs) on HDPE/GO and HDPE/PE-g-GO composites, in vitro. The statistically significant increase in metabolically active cell over different time periods in culture for up to 6 days in MC3T3 and 7 days for hMSCs was observed, irrespective of the substrate composition. Such observation indicated that HDPE with GO or PE-g-GO addition (up to 3 wt %) can be used as cell growth substrate. The extensive proliferation of cells with oriented growth pattern also supported the fact that tailored GO addition can support cellular functionality in vitro. Taken together, the experimental results suggest that the PE-g-GO in HDPE can effectively be utilized to enhance both mechanical and

  3. Melting and crystallization behavior of partially miscible high density polyethylene/ethylene vinyl acetate copolymer (HDPE/EVA) blends

    International Nuclear Information System (INIS)

    Highlights: • HDPE/EVA blends undergo phase separation, making it an interesting topic to investigate the relationships between miscibility and crystallization. • Influences from blending on the crystallization kinetics were successfully evaluated by Friedman's and Khanna's method. • X-ray diffraction studies revealed that blending with EVA the unit length of the unit cell of the HDPE increases. • Thermal fractionation method was successfully used to characterize the co-crystallization in HDPE/EVA blends. - Abstract: Crystallization studies on HDPE/EVA blends and the individual components were performed with differential scanning calorimetry (DSC) technique and wide angle X-ray scattering (WAXS). Influences of blending on the crystallization kinetics of each component in HDPE/EVA mixture were evaluated by Friedman's activation energy and Khanna's crystallization rate coefficient (CRC). The addition of more HDPE into the EVA matrix causes more heterogeneous nucleation while the addition of EVA would hinder the nucleation of HDPE at the beginning of cooling process. Inter-molecular interaction in the melt facilitated the crystallization of both EVA and HDPE components. X-ray diffraction studies revealed that HDPE and EVA have orthorhombic unit cell. Blending with EVA did not affect the crystalline structure of HDPE. In addition, a little shift of (1 1 0), (2 0 0) and (0 2 0) crystalline peaks toward lower 2θ values of samples indicating a little increase of unit cell parameters of the orthorhombic unit cell of polyethylene. Thermal fractionation results showed that co-crystallization took place in the HDPE/EVA blend. All those results indicated that the polymer pair we choose was partially miscible

  4. Melting and crystallization behavior of partially miscible high density polyethylene/ethylene vinyl acetate copolymer (HDPE/EVA) blends

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang; Zou, Huawei, E-mail: hwzou@163.com; Liang, Mei, E-mail: liangmeiww@163.com; Cao, Ya

    2014-06-01

    Highlights: • HDPE/EVA blends undergo phase separation, making it an interesting topic to investigate the relationships between miscibility and crystallization. • Influences from blending on the crystallization kinetics were successfully evaluated by Friedman's and Khanna's method. • X-ray diffraction studies revealed that blending with EVA the unit length of the unit cell of the HDPE increases. • Thermal fractionation method was successfully used to characterize the co-crystallization in HDPE/EVA blends. - Abstract: Crystallization studies on HDPE/EVA blends and the individual components were performed with differential scanning calorimetry (DSC) technique and wide angle X-ray scattering (WAXS). Influences of blending on the crystallization kinetics of each component in HDPE/EVA mixture were evaluated by Friedman's activation energy and Khanna's crystallization rate coefficient (CRC). The addition of more HDPE into the EVA matrix causes more heterogeneous nucleation while the addition of EVA would hinder the nucleation of HDPE at the beginning of cooling process. Inter-molecular interaction in the melt facilitated the crystallization of both EVA and HDPE components. X-ray diffraction studies revealed that HDPE and EVA have orthorhombic unit cell. Blending with EVA did not affect the crystalline structure of HDPE. In addition, a little shift of (1 1 0), (2 0 0) and (0 2 0) crystalline peaks toward lower 2θ values of samples indicating a little increase of unit cell parameters of the orthorhombic unit cell of polyethylene. Thermal fractionation results showed that co-crystallization took place in the HDPE/EVA blend. All those results indicated that the polymer pair we choose was partially miscible.

  5. Resistivity-Temperature Behavior of CB-Filled HDPE Foaming Composites

    Institute of Scientific and Technical Information of China (English)

    LI Ji-xin; ZHANG Guo; LI Zhuo-shi; WANG Xin-lei; LIU Xiu-qi

    2008-01-01

    High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black(ACET)and super conductive carbon black(HG-IP)as conductive filler,low-density polyethylene(LDPE)as the second component,ethylene-vinyl acetate(EVA)and ethylene propylene rubber(EPR) as the third component, azobisformamide(AC)as foamer,and dicumyl peroxide(DCP)as cross-linker.The structure and resistivity-temperature behavior of high-density polyethylene(HDPE)/CB foaming conductive composites were investigated.Influences of carbon black,LDPE,EVA,EPR,AC,and DCP on the foaming performance and resistivity-temperature behavior of HDPE/CB foaming conductive composites were also studied.The results reveal that HDPE/CB foaming conductive composite exhibits beaer switching characteristic;ACET-filled HDPE foaming conductive composite displays better positive temperature coefficient(PTC)effect;whereas super conductive carbon black(HG-1P)-filled HDPE foaming conducive composite shows better negative temperature coefficient(NTC)effect.

  6. Comportamento Viscoelástico Linear e Morfologia de Blendas PP/HDPE

    Directory of Open Access Journals (Sweden)

    Souza Adriana M. C. de

    2001-01-01

    Full Text Available Neste trabalho, o efeito da composição da blenda PP/HDPE e da temperatura no comportamento viscoelástico linear e na morfologia destas blendas foi estudado. A tensão interfacial entre PP e HDPE foi avaliada utilizando o espectro de relaxação das blendas, seguindo as análises de Gramespacher e Meissner[1]. Os resultados indicaram que existe uma faixa de composições da blenda PP/HDPE para a qual é possível utilizar as análises de Gramespacher e Meissner[1] na obtenção da tensão interfacial entre polímeros utilizando-se medidas reológicas. A compatibilização da blenda PP/HDPE também foi estudada através de análises morfológicas e da tensão interfacial entre os seus componentes. Três compatibilizantes foram testados: EPDM, SEBS e EVA. Curvas de emulsão relacionando o raio médio da fase dispersa e a tensão interfacial com a concentração de compatibilizante adicionado à blenda foram obtidas. Foi mostrado que o EPDM foi mais eficiente como agente emulsificante para a blenda PP/HDPE que o EVA e o SEBS.

  7. Desarrollo del proceso de moldeo por inyección de polvos para la obtención de piezas de alúmina : aplicación a la producción de brackets dentales

    OpenAIRE

    Thomas Vielma, Patricia

    2008-01-01

    En la presente Tesis Doctoral se ha desarrollado el proceso de moldeo por inyección de polvos para la obtención de piezas de alúmina con aplicaciones en ortodoncia. En primer lugar se formuló un sistema ligante constituido por polietileno de alta densidad (HDPE), parafina (PW) y ácido esteárico (SA). Para ello se estudió la miscibilidad de dos tipos de ceras, comúnmente empleadas en el proceso PIM, con el polietileno de alta densidad (HDPE) mediante la técnica de autonucleac...

  8. Preparation and characterization of electron-beam treated HDPE composites reinforced with rice husk ash and Brazilian clay

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, A.V., E-mail: angelortiz@ipen.br [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Teixeira, J.G.; Gomes, M.G.; Oliveira, R.R. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Díaz, F.R.V. [Metallurgical and Materials Engineering Department, Polytechnic School, University of São Paulo Av. Prof. Mello de Morais 2463, São Paulo, SP 05508-900 (Brazil); Moura, E.A.B. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil)

    2014-08-15

    Highlights: • We examine changes in HDPE properties when waste and clay are used as reinforcement. • The addition of only 3% of clay leads to important gains in HDPE properties. • The use of electron-beam contributes to greater improvements in material properties. • We observe 85% of cross-linking degree for the HDPE when treated with e-beam. - Abstract: This work evaluates the morphology, mechanical and thermo-mechanical properties of high density polyethylene (HDPE) composites. HDPE reinforced with rice husk ashes (80:20 wt%), HDPE reinforced with clay (97:3 wt%) and HDPE reinforced with both rice husk ashes and clay(77:20:3 wt%) were obtained. The Brazilian bentonite chocolate clay was used in this study. This Brazilian smectitic clay is commonly used to produce nanocomposites. The composites were produced by melting extrusion process and then irradiation was carried out in a 1.5 MeV electron-beam accelerator (room temperature, presence of air). Comparisons using the irradiated and non-irradiated neat polymer, and the irradiated and non-irradiated composites were made. The materials obtained were submitted to tensile, flexural and impact tests. Additionally HDT, SEM and XRD analyses were carried out along with the sol–gel analysis which aimed to assess the cross-linking degree of the irradiated materials. Results showed great improvement in most HDPE properties and a high cross-linking degree of 85% as a result of electron-beam irradiation of the material.

  9. Effects of Cross-Linking on the Hydrostatic Pressure Testing for HDPE Pipe Material using Electron Beam Machine

    International Nuclear Information System (INIS)

    One of the most inventive, sustainable strategies used in engineering field is to improve the quality of material and minimize production cost of material for example in this paper is HDPE material. This is because HDPE is an oil base material. This paper proposes to improve its hydrostatic pressure performance for HDPE pipe. The burst test is the most direct measurement of a pipe materials resistance to hydrostatic pressure. Test will be conducted in accordance with ASTM standard for HDPE pipe that undergo electron beam irradiation cross-linking. Studies show the effect of electron beam irradiation will improve the mechanical properties of HDPE pipe. When cross-linking is induced, the mechanical properties such as tensile strength and young modulus is increase correspond to the radiation dose. This happen because the structure of HDPE, which is thermoplastic change to thermosetting. This will indicate the variability of irradiation dose which regard to the pipe pressure rating. Hence, the thickness ratio of pipe will be re-examining in order to make the production of HDPE pipe become more economical. This research review the effects of electron beam on HDPE pipe, as well as to reduce the cost of its production to improve key properties of selected plastic pipe products. (author)

  10. Preparation and characterization of electron-beam treated HDPE composites reinforced with rice husk ash and Brazilian clay

    International Nuclear Information System (INIS)

    Highlights: • We examine changes in HDPE properties when waste and clay are used as reinforcement. • The addition of only 3% of clay leads to important gains in HDPE properties. • The use of electron-beam contributes to greater improvements in material properties. • We observe 85% of cross-linking degree for the HDPE when treated with e-beam. - Abstract: This work evaluates the morphology, mechanical and thermo-mechanical properties of high density polyethylene (HDPE) composites. HDPE reinforced with rice husk ashes (80:20 wt%), HDPE reinforced with clay (97:3 wt%) and HDPE reinforced with both rice husk ashes and clay(77:20:3 wt%) were obtained. The Brazilian bentonite chocolate clay was used in this study. This Brazilian smectitic clay is commonly used to produce nanocomposites. The composites were produced by melting extrusion process and then irradiation was carried out in a 1.5 MeV electron-beam accelerator (room temperature, presence of air). Comparisons using the irradiated and non-irradiated neat polymer, and the irradiated and non-irradiated composites were made. The materials obtained were submitted to tensile, flexural and impact tests. Additionally HDT, SEM and XRD analyses were carried out along with the sol–gel analysis which aimed to assess the cross-linking degree of the irradiated materials. Results showed great improvement in most HDPE properties and a high cross-linking degree of 85% as a result of electron-beam irradiation of the material

  11. FRACTURE MECHANICS TESTING OF HIGH DENSITY POLYETHYLENE (HDPE PIPE MATERIAL WITH COMPACT TENSION (CT SPECIMENS

    Directory of Open Access Journals (Sweden)

    VLAD ULMANU

    2011-09-01

    Full Text Available The lifetime of polyethylene pipes used for water and natural gas distribution is usually estimated based on relatively long-time creep tests. The pipes fail in service at room temperature and low stress in brittle mode called "long-time brittle failure". In order to economically predict the long term creep performance of HDPE pipes, short term static or fatigue tests are used, in which the crack growth rate is substantially increased. One of the recent tests capable of presenting results useful for HDPE pipe failure prediction is based on the concepts of fracture mechanics. The paper the tests performed on CT specimens cut directly from the HDPE gas pipe in order to determine the fracture toughness the crack propagation rate in fatigue and the crack propagation rate at different loading speeds. The crack propagation speed was monitored by video-controlled technique.

  12. Characterization of high energy milled UHMWPE and its blends with HDPE

    International Nuclear Information System (INIS)

    The ultra-high molecular weight polyethylene (UHMWPE) has many excellent properties as high impact resistance, low abrasion and low coefficient of friction. However, it has a high viscosity which makes its processing by conventional methods more difficult. The purpose of the present work was to study the high energy mechanical milling of UHMWPE powder in an Attritor type mill at different times of milling. Subsequently, blends of HDPE with UHMWPE were prepared. The milled UHMWPE powder was characterized by SEM, XRD, DSC, FRX and apparent density. Specimen of blends in different concentrations and its polymeric films were prepared, which were characterized by optical microscopy with polarized light. Thus it was possible to observe that the milling time influences the morphological, chemical and physical features of UHMWPE and that the blend of HDPE with milled UHMWPE showed better dispersion of the PEUAMM than the blend of HDPE with non-milled UHMWPE. (author)

  13. La densidad urbana como variable de análisis de la ciudad: El caso de Cuenca, Ecuador

    Directory of Open Access Journals (Sweden)

    M. Augusta Hermida

    2015-09-01

    Full Text Available El debate teórico sobre la ciudad dispersa versus la ciudad compacta, en el mundo y particularmente en América Latina, pone en la palestra los aspectos clave necesarios para proponer un nuevo modelo de ciudad, donde la calidad de vida de las presentes y futuras generaciones sea el punto focal de reflexión. A través del estudio del estado del arte sobre el tema se concluye que el regreso a la ciudad compacta es la alternativa para un posible desarrollo sustentable en las ciudades intermedias de América Latina. En el caso de Cuenca, se concentra el estudio en las densidades de la ciudad desde los años cincuenta hasta nuestros días. Sorprende comprobar que Cuenca fue una ciudad compacta con alta calidad de vida pero que, paulatinamente, se está expandiendo innecesariamente, con todos los problemas que ello implica.

  14. Servidores web de altas prestaciones

    OpenAIRE

    Castillo Valdivieso, Pedro; Bernier Villamor, Jos?? Luis; Mora Garc??a, Antonio Miguel; Garc??a-S??nchez, Pablo; Garc??a Arenas, Mar??a Isabel

    2013-01-01

    Para crear un sitio web exitoso debemos ser cuidadosos con muchos detalles, ya que la arquitectura, la selecci??n del hardware, o la implementaci??n de las aplicaciones afectar??n al rendimiento del sistema completo. Es m??s, un sitio que no est?? preparado para dar servicio a un n??mero creciente de clientes o usuarios, a la larga puede llevar al fracaso a la empresa. En este trabajo, se presenta una visi??n general de la nueva asignatura Servidores Web de Altas Prestaciones, del nuevo plan...

  15. Estudo da influência de resíduos catalíticos na degradação de plásticos reciclados (Blenda HDPE/PP e PET provenientes de lixo urbano

    Directory of Open Access Journals (Sweden)

    Santos Amélia S. F.

    1999-01-01

    Full Text Available A degradação derivada do processamento, uso, descarte, lavagem e reprocessamento foram caracterizados neste estudo. Para o HDPE/PP pós-consumo, a degradação foi estudada em função da presença de garrafas de HDPE/LDPE reprocessadas (recicladas e da presença de tampas e rótulos de LDPE e PP. Esses materiais mostraram uma influência significativa na degradação total de HDPE/PP apenas quando presentes em conjunto. Os resíduos que apresentaram menor estabilidade termo-oxidativa foram os rótulos e tampas de LDPE e PP. As análises usadas na caracterização da influência destes resíduos foram espectroscopia do Infra-vermelho (IR e Calorimetria Diferencial Exploratória (tempo de indução oxidativa - OIT. Além disso, a degradação do PET foi estudada em função das condições de lavagem e da presença de resíduos de soda cáustica e adesivo. Foram usadas medidas de viscosidade intrínseca e de titulação para caracterizar estas variáveis. Foi observado que apesar do uso de altas temperaturas (80 ºC durante a lavagem, a extensão de tempo desta etapa (5 ou 15 min não afetou a degradação do PET, pelo menos não em níveis detectáveis pelas análises. No entanto, a remoção do resíduo de adesivo mostrou uma influência significativa na degradação catalítica do PET.

  16. HDPE/PET共混物的原位反应增容%In Situ Reactive Compatibilization of HDPE/PET Blends

    Institute of Scientific and Technical Information of China (English)

    李海; 王玉领; 吉旭; 李忠明

    2010-01-01

    采用"一步挤出法"制备了高密度聚乙烯/聚对苯二甲酸乙二(醇)酯(HDPE/PET)共混物.通过傅里叶变换红外光谱(FT-IR)分析证明了HDPE与甲基丙烯酸缩水甘油酯(GMA)的接枝共聚物HDPE-g-GMA的形成.通过力学性能测试、扫描电镜(SEM)观察、差示扫描量热(DSC)分析和维卡软化点测试评价了共混物的增容效果.结果表明,过氧化二异丙苯(DCP)含量对体系增容效果的影响要大于单体含量的影响;当DCP含量不超过0.25 phr时,增容效果随其含量的增加而提高,但当DCP含量为0.30phr时增容效果有所下降.采用"一步挤出法"进行HDPE/PET共混物的原位反应增容是可行的.

  17. Tensile behaviour and properties of a bone analogue composite (HA, HDPE) crosslinked by gamma radiation

    International Nuclear Information System (INIS)

    A natural composite material, hydroxyapatite (HA) and high density polyethylene (HDPE) crosslinked by ionizing radiations is been developed as a bioactive analogue material for bone replacement. Mechanical properties of the composites irradiated up to 300 kGy under tensile tests was studied. Gel content and micrographs of different composite fractures are shown. (author)

  18. Structure, mechanical properties and friction behavior of UHMWPE/HDPE/carbon nanofibers

    International Nuclear Information System (INIS)

    Effects of untreated and pretreated carbon nanofibers (CNFs) on the crystallization behavior, friction behavior, and mechanical properties of ultra high molecular weight polyethylene (UHMWPE)/high density polyethylene (HDPE) nanocomposites prepared by a twin-screw extrusion were studied. The differential scanning calorimetry and wide angle X-ray diffraction measurements indicated that the addition of CNFs impacted the temperature of crystallization, but had no significant effects on the crystalline structure of the UHMWPE/HDPE blend. The degree of crystallinity, and the tensile strength and modulus of the UHMWPE/HDPE systems exhibited an increasing trend initially with addition of CNFs, followed by a decrease at higher contents. With the increase of untreated CNF content, the friction coefficient of UHMWPE/HDPE was decreasing and displayed less change in the process of friction. The microstructure features on the fracture surfaces and friction surfaces of the polymer blend and the nanocomposites were analyzed in detail by scanning electron microscope observations. The degree of crystallinity of the nanocomposites with the pretreated CNFs exhibited a decrease due to the better interface adhesion compared to that in the nanocomposites with the same loading untreated CNFs. The enhancement in tensile strength of nanocomposites containing 0.5 wt% treated CNFs was four times higher (32%) than that of the nanocomposites containing untreated CNFs (8%) over that of the pure polymer

  19. Percolation based enhancement in effective thermal conductivity of HDPE/LBSMO composites

    Indian Academy of Sciences (India)

    Madhusree Kole; D Tripathi; T K Dey

    2012-08-01

    Thermal conductivity of composites with electrically conducting La0.7Ba0.15Sr0.15MnO3 (LBSMO) filler of nanometric grain size in HDPE matrix is investigated. Volume fraction of LBSMO fillers was varied between 0 and 0.30. SEM photographs of the composites show the presence of clusters and percolative paths, particularly for composites prepared with higher filler volume fractions. The effective thermal conductivity of the composites displays significant enhancement with increasing filler content in HDPE. A maximum enhancement of ∼65% compared to that for pure HDPE has been observed for composite with 0.30 volume fraction of LBSMO filler. Most of the models those are generally used to predict the properties of two phase mixtures, has been found either to under/overestimate the measured effective thermal conductivity of the composites. We confirm that the observed rapid increase in the effective thermal conductivity of HDPE/LBSMO composite over the studied range of filler volume fraction (viz. 0–0.30), is predicted very well, considering the effect of percolation as proposed by Zhang et al (2009).

  20. Morphology and properties of SEBS block copolymer compatibilized PS/HDPE blends

    Czech Academy of Sciences Publication Activity Database

    Rek, V.; Vranješ, N.; Šlouf, Miroslav; Fortelný, Ivan; Jelčic, Ž.

    2008-01-01

    Roč. 40, č. 3 (2008), s. 237-251. ISSN 0095-2443 Grant ostatní: Ministry of Science, Education and Sport(HR) 0125059 Institutional research plan: CEZ:AV0Z40500505 Keywords : aPS/HDPE/SEBS blends * morphology * processing * rheological Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.658, year: 2008

  1. Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

    International Nuclear Information System (INIS)

    In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

  2. Morphology, rheology and electrical resistivity of PLLA/HDPE/CNT nanocomposites: Effect of maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Li-na; Chen, Jie; Dai, Jian; Chen, Hai-ming; Yang, Jing-hui [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Wang, Yong, E-mail: yongwang1976@163.com [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, Chao-liang [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China)

    2015-02-15

    As a part of serial work about tuning the selective location of carbon nanotubes (CNTs) in immiscible polymer blends, this work reports the effects of component polarity and viscosity ratio between components on the selective location of CNTs and the resultant electrical resistivity of the nanocomposites. To achieve the research aim, maleic anhydride (MA) was grafted onto poly(L-lactide) (PLLA) main chain through a reactive compounding processing. After that, different contents of CNTs were incorporated into blends of high density polyethylene (HDPE) and PLLA (or PLLA-g-MA). The morphologies of the ternary nanocomposites and the selective location of CNTs in the nanocomposites were characterized using scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructure of nanocomposites and the dispersion of CNTs were further proved by rheological measurement. Finally, the electrical resistivity of nanocomposites containing different CNT contents was measured. The results showed that through increasing the polarity of PLLA and decreasing the melt viscosity, CNTs were kinetically trapped at the blend interface region. Consequently, largely decreased percolation threshold was achieved for the PLLA-g-MA/HDPE/CNT nanocomposites. The morphological changes as well as the rheological properties were also comparatively analyzed. - Highlights: • PLLA/HDPE/CNT and PLLA-g-MA/HDPE/CNT composites were prepared. • Different selective location states of CNTs were achieved in different composites. • Selectively located CNTs at the interface resulted in lower percolation threshold.

  3. The Tension and Puncture Properties of HDPE Geomembrane under the Corrosion of Leachate

    Directory of Open Access Journals (Sweden)

    Kai Xiao

    2013-09-01

    Full Text Available To investigate the gradual failure of high-density polyethylene (HDPE geomembrane as a result of long-term corrosion, four dynamic corrosion tests were conducted at different temperatures and durations. By combining tension and puncture tests, we systematically studied the variation law of tension and puncture properties of the HDPE geomembrane under different corrosion conditions. Results showed that tension and puncture failure of the HDPE geomembrane was progressive, and tensile strength in the longitudinal grain direction was evidently better than that in the transverse direction. Punctures appeared shortly after puncture force reached the puncture strength. The tensile strength of geomembrane was in inversely proportional to the corrosion time, and the impact of corrosion was more obvious in the longitudinal direction than transverse direction. As corrosion time increased, puncture strength decreased and corresponding deformation increased. As with corrosion time, the increase of corrosion temperature induced the decrease of geomembrane tensile strength. Tensile and puncture strength were extremely sensitive to temperature. Overall, residual strength had a negative correlation with corrosion time or temperature. Elongation variation increased initially and then decreased with the increase in temperature. However, it did not show significant law with corrosion time. The reduction in puncture strength and the increase in puncture deformation had positive correlations with corrosion time or temperature. The geomembrane softened under corrosion condition. The conclusion may be applicable to the proper designing of the HDPE geomembrane in landfill barrier system.

  4. SAXS investigation of latent track structure in HDPE irradiated with high energy Fe ions

    International Nuclear Information System (INIS)

    Semi-crystalline high density polyethylene (HDPE) samples were irradiated with 1.157 GeV 56Fe ion beams to fluences ranging from 1 × 1011 to 6 × 1012 ions/cm2. The radiation induced changes in nano/microstructure were investigated with small angle X-ray scattering (SAXS) technique. The scattering contributions from HDPE matrix and ion tracks are successfully separated and analyzed through tilted SAXS measurements with respect to the X-ray beam direction. Lorentz correction, one-dimensional correlation function calculation, fractal nature analysis of the isotropic scattering pattern reveal that HDPE long period polymeric structures are damaged and new materials, possibly clusters of carbon-rich materials, are formed inside the ion tracks. Least square curve fitting of the scattering contribution from the ion track reveals that the track is composed of a core of about 5.3 nm in radius, characterized by a significant density deficit compared to the virgin HDPE, surrounded by a shell of about 4.3 nm in thickness with less density reduction

  5. Case study installation of a HDPE curtain wall with sheetpile tie-in on both ends

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, R.M.; Maltese, P.C. [Geo-Con, Monroeville, PA (United States)

    1997-12-31

    The plans for eliminating the off-site migration of non-aqueous phase liquid (NAPL) from a refinery into a nearby river included the installation of a High Density Polyethylene (HDPE) curtain wall and an underdrain system. A 640 m (2100 lineal feet) HDPE Curtain Wall was installed along the river boundary, tying into an existing sheet pile wall on both ends. The wall varied from approximately 4.5 m (15 feet) deep at the northern end to about 7 m (23 feet) deep at the southern end, running approximately 3 to 3.6 m (10 to 12 feet) inland of an existing wooden bulkhead. The curtain wall was successfully installed through a slurry supported trench. A 930 m (3050 lineal feet) interception/collection trench was installed parallel to the HDPE Curtain Wall, continuing on beyond the curtain wall on the southern end. The depth of the trench varied from approximately 3 to 4 m (10 to 13 feet) deep. A 20.32 cm (8 inch) diameter perforated HDPE header pipe was placed in the trench to convey groundwater and product to two sumps. The trench is 53.34 cm (21 inches) wide and contained aggregate to approximately 0.9 m (3 feet) below ground. This work was accomplished using the bio-polymer slurry drainage trench (BP Drain) technique. This paper briefly describes the construction methods utilized during this project, specifically HDPE curtain wall installation thru a bentonite slurry and tie-in to the existing sheet pile wall.

  6. Case study installation of a HDPE curtain wall with sheetpile tie-in on both ends

    International Nuclear Information System (INIS)

    The plans for eliminating the off-site migration of non-aqueous phase liquid (NAPL) from a refinery into a nearby river included the installation of a High Density Polyethylene (HDPE) curtain wall and an underdrain system. A 640 m (2100 lineal feet) HDPE Curtain Wall was installed along the river boundary, tying into an existing sheet pile wall on both ends. The wall varied from approximately 4.5 m (15 feet) deep at the northern end to about 7 m (23 feet) deep at the southern end, running approximately 3 to 3.6 m (10 to 12 feet) inland of an existing wooden bulkhead. The curtain wall was successfully installed through a slurry supported trench. A 930 m (3050 lineal feet) interception/collection trench was installed parallel to the HDPE Curtain Wall, continuing on beyond the curtain wall on the southern end. The depth of the trench varied from approximately 3 to 4 m (10 to 13 feet) deep. A 20.32 cm (8 inch) diameter perforated HDPE header pipe was placed in the trench to convey groundwater and product to two sumps. The trench is 53.34 cm (21 inches) wide and contained aggregate to approximately 0.9 m (3 feet) below ground. This work was accomplished using the bio-polymer slurry drainage trench (BP Drain) technique. This paper briefly describes the construction methods utilized during this project, specifically HDPE curtain wall installation thru a bentonite slurry and tie-in to the existing sheet pile wall

  7. TransAlta: More than a utility

    International Nuclear Information System (INIS)

    TransAlta Utilities Corporation is Canada's largest privately owned utility and is also a major coal mining company. In 1989, TransAlta produced 20.9% of all coal mined in Canada. A brief history of TransAlta is presented along with TransAlta's present coal operations and plans for the next three years. An overview is presented of how TransAlta Fuel Supply is organized to utilize contracted mining operation, engineering and environmental services and in-house capabilities. Recent strategic initiatives to improve organizational efficiency and the mining operations are discussed. These range from developing a common departmental vision to modifying major mining equipment. TransAlta's proactive role in clean coal combustion such as low NOx-SOx burner, integrated combined cycle gasification, and other energy research projects is reviewed. A summary is provided of recent participation of TransAlta in environmental management initiatives. Recent successes of TransAlta's unregulated subsidiary in the development of cogeneration facilities and the future of this area of business are discussed. 8 refs., 4 figs

  8. Alta peab tasuma Kalevile mais / Kersti Saar

    Index Scriptorium Estoniae

    Saar, Kersti

    2008-01-01

    Indrek Rahumaa juhitav Alta Capital peab tasuma Oliver Kruudale Kalevi tütarfirmade eest 660 miljonit krooni hiljemalt 30. maiks. Vt. samas: Investorid teavad tehingu hinda ja lõplikku tähtaega. Diagramm: Kalevi turuväärtus jääb Alta müügihinnale alla

  9. Application of HDPE pipe in sinking plate same-story drainage system of high-rising building%HDPE 管在高层住宅降板同层排水系统中的应用

    Institute of Scientific and Technical Information of China (English)

    李庆明; 李燕敏

    2015-01-01

    北京香墅湾一号西区项目中高层住宅楼采用降板同层排水系统,生活污废水立管、支管、通气立管采用高密度聚乙烯(HDPE)管,热熔对焊连接或电熔管箍连接。介绍了 HDPE 管材选取和管道安装方法,并对管道安装质量控制重点进行了详细分析,以期为 HDPE 管在高层住宅降板同层排水系统中的应用提供参考。%The sinking plate same-story drainage system was used in the high-rising building of the west district of Beijing Xianshuwan No.1 estate.The high density polyethylene pipe (HDPE)was used as domestic sewerage vertical drainage pipe,branch pipe,and vertical venting pipe and the hot melting con-necting technique or electric melting pipe coupling connecting technique were used for pipe connection.This paper introduced the methods for HDPE pipe material selecting and pipe installing and analyzed the quality control of pipe installation in detail.This paper might be the reference for application of HDPE pipe in sinking plate same-story drainage system in high-rising building.

  10. Fabrication and materials properties of high-density polyethylene (HDPE)/biphasic calcium phosphate (BCP) hybrid bone plates

    International Nuclear Information System (INIS)

    Biphasic calcium phosphate-reinforced high-density polyethylene (BCP/HDPE) hybrid composite is a new orthopedic biomaterial, which was made to simulate a natural bone composition. Calcium phosphate systems and HDPE hybrid composites have been used in biomedical applications without any inflammatory response. Differences in natural bone of both materials have motivated the use of coupling agents to improve their interfacial interfacial interactions. The composites were prepared using medical grade BCP powder and granular polyethylene. This material was produced by replacing the mineral component and collagen soft tissue of the bone with BCP and HDPE, respectively. As expected, increased volume fraction of either reinforcement type over 0 ∼ 50 vol.% resulted in a increased Vickers hardness and Young's modulus. Thus, BCP particle-reinforced HDPE composites possessed improved material and mechanical properties. BCP particles-reinforced composites were anisotropic due to an alignment of the particles in the matrix during a processing. On the other hand, bending and tensile strength was dramatically changed in the matrix. To change the material and mechanical properties of HDPE/BCP composites, the process of a blending was used, and its effect on the microstructure and mechanical proprieties of HDPE/BCP composites were investigated by means of FT-IR/ATR spectroscopy, XRD, FE-SEM, Vickers Hardness Testing Machine, Universal Testing Machine, Mercury Porosimeter and Ultrasonic Flaw Detector at room temperature. For the evaluation of the cell viability and proliferation onto the external surface of HDPE/BCP hybrid plates with a HaCaT cell line, which is a multipotent cell line able to differentiate towards different phenotypes under the action of biological factors, has been evaluated with in vitro studies and quantified by colormetric assays. These findings indicate that the HDPE/BCP hybrid plates are biocompatible and non-toxic

  11. Studi Penggunaan Adsorben Sintetis Kalsium Maleat – Grafting – High Density Polyethylene (HDPE) Pada Pemisahan Karotenoid Dari Biodiesel Minyak Sawit

    OpenAIRE

    Lubis, Ahmad Husni

    2011-01-01

    Study of using synthetic adsorbent of Calsium Maleic – grafting – HDPE (High Density Polyethylene) has been doing in separating of palm oil biodiesel, where adsorbent was produced by grafting polyethylene with maleic anhydride homogenly with the presence of benzoil peroxide as inisiator. The product was maleic anhydride- grafting – HDPE, then continued by characterization with melting point analysis, evaluation of grafting degree and functional groups analysis by FT-IR spectrophotometer. Male...

  12. Study of the Mechanical and Morphology Properties of Recycled HDPE Composite Using Rice Husk Filler

    Directory of Open Access Journals (Sweden)

    Jia Ying Tong

    2014-01-01

    Full Text Available WPCs are being used in a large number of applications in the automotive, construction, electronic, and aerospace industries. There are an increasing number of research studies and developments in WPC technology involving rice husk as fillers. This study investigated the effects of different compositions of rice husk (RH filler on the mechanical and morphological properties of recycled HDPE (rHDPE composite. The composites were prepared with five different loading contents of RH fibers (0, 10, 20, 30, and 40 wt% using the twin screw extrusion method. Maleic acid polyethylene (MAPE was added as a coupling agent. Results showed that tensile and flexural properties improved with increasing RH loading. However, the impact strength of the composites decreased as the RH loading increased. SEM micrographs revealed good interfacial bonding between the fiber and polymer matrix.

  13. Behavior of antioxidants in HDPE geomembranes used in municipal solid waste landfills

    OpenAIRE

    Pons, Carlota; FARCAS, Fabienne; MKADEMI, Hela; Richaud, Emmanuel; Fayolle, Bruno

    2012-01-01

    The main objective of this work is to determine the behaviour of process stabilizers (such as phenolic and phosphite types) present in PE films (thin samples) and in HDPE geomembranes (thick samples) incubated in municipal solid waste (MSW) landfill leachate. In order to determine the parameters of a non-empirical kinetic model for polyethylene ageing, we have to take into account the stabilizers diffusion and extraction phenomena. Indeed antioxidants (AO) depletion can be governed by an extr...

  14. Mercado para produtos reciclados à base de PET/HDPE/Ionômero Market for PET/HDPE/Ionomer recycled products

    Directory of Open Access Journals (Sweden)

    Elen B. Pacheco

    1999-12-01

    Full Text Available A expansão do mercado de poli(tereftalato de etileno (PET, considerada um fenômeno mundial, está acontecendo no Brasil. Hoje, o principal mercado para o PET é o de bebidas carbonatadas. O uso de PET em lugar do vidro vem trazendo inúmeras vantagens, incluindo menor peso, maior resistência ao impacto e menores custos de transporte. Foram estudados possíveis mercados para a mistura PET/HDPE, na proporção de 75/25, acrescida de uma pequena quantidade de compatibilizante. Os resultados do estudo indicam que possíveis mercados para o mistura poderá incluir o de embalagens para usos especiais e partes de automóvel.The expansion of the market for polyethylene terephthalate (pet, considered a world phenomenon, is happening in brazil. The main market for pet is the soft drink bottles. The use of pet instead of glass brings several advantages, including lighter weight, better impact resistance, and lower transportation costs. Possible markets were studied for pet/hdpe blends in proportion 75/25 with small amounts of a compatibilizer. The results of the study indicate that possible markets would be containers for special uses and car parts.

  15. Study of herbicide ametryne degradation in HDPE packaging using the advanced oxidation process by ionizing radiation

    International Nuclear Information System (INIS)

    This study is part of the project with the objective to evaluate pesticides degradation for decontamination of commercial polymeric packaging of high density polyethylene, HDPE, used in agriculture. The herbicide used to this study was the herbicide ametryne (commercial name, Gesapax 500), due to its great use, mainly on field crops and on corn. Ametryne is commercialized since 1975, and, depending on the pesticide formulation and type of application, residues may be detectable in water, soil and on the surfaces for months or years. In order to evaluate the efficiency of radiation processing on removal the pesticides contamination, HDPE packaging were irradiated using Radiation Dynamics Electron Beam Accelerator with 1,5 MeV energy and 37 kW, in batch system. The samples were irradiated with water, in various absorbed doses. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.986, and the relative standard deviation was lower than 10%. The radiation processing yield was evaluated by the rate of ametryne degradation and by the destruction G-value (Gd). The electron beam irradiation processing, showed high efficiency in destroying ametryne in the HDPE packaging when the samples were irradiated in presence of small quantities of water. (author)

  16. Effect of phenol formaldehyde resin as vulcanizing agent on flow behavior of HDPE/PB blend

    Directory of Open Access Journals (Sweden)

    Moayad N. Khalaf

    2014-07-01

    Full Text Available Thermoplastic elastomer (TPE based on High density polyethylene (HDPE/polybutadiene (HDPE/PB = 70/30 parts blends containing 1, 3, 5, 7 and 10 wt.% of dimethylol phenolic resin as a vulcanizing agent in the presence of SnCl2 as catalyst was prepared. The dimethylol phenolic resin was prepared in our laboratory. The blends were compounded in mixer-60 attached to a Haake rheochord meter-90. The rheological properties were measured at temperatures 140, 160, 180 and 200 °C. The linearity of the flow curve appeared for 5% of the vulcanizing agent. The shear stress and shear viscosity have increased upon increasing the shear rate over a range of loading levels of vulcanizing agent of 1%, 3%, 5%, 7% and 10%. This may be attributed to the increased vulcanization between polyethylene and the rubber blend. The flow behavior index of the system shows a pseudo plastic nature behavior (since n < 1. The consistency index (K increased with the increase in the phenol formaldehyde resin content and the temperature. Hence, the increase in the value of the consistency index (K of the polymer melts refers to more viscous materials prepared. The activation energy for the TPE blends fluctuated indicating that there is phase separation; where each polymer behaved separately. This study showed that HDPE/PB blends are characterized with good rheological properties, which can be recommended to be processed with the injection molding technique.

  17. Electric conductivity and dielectric properties of HDPE-TlInS2 composites

    International Nuclear Information System (INIS)

    Polymer-semiconductor composites are prepared from a homogeneous mixture of powders of high density polyethylene (HDPE) and the TlInS2 semiconductor. The electric conductivity (σac) and dielectric properties (ε'and ε) of the composites as a function of the volume fraction of the TlInS2 ferroelectric (0-60%), temperature (20-150 degrees Celsius), and frequency (102-106 Hz) of the measured electric field are studied. The semi logarithmic plot of the temperature dependence of conductivity, i.e., the lnσac-temperature curve, comprises three regions; one of them corresponds to the low temperature portion of the curve where σac weakly depends on temperature, while in the other two regions σac exhibits a strong temperature dependence. The plot of the frequency dependence of σac for the HDPE-TlInS2 composites shows that σac increases exponentially and nonlinearly at low and high frequencies, respectively. The observed decrease in ε' with increasing frequency is representative of a dielectric relaxation process. The occurrence of this relaxation process is also confirmed by the fact that the ε(f) plot exhibits a maximum at 10 kHz. It is assumed that the relaxation processes in the HDPE-TlInS2 composite structures are attributed to interfacial polarization and the local mobility of the polar components and short segments of the polymer backbone. (authors)

  18. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    International Nuclear Information System (INIS)

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm−1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese

  19. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Aras, Neny Rasnyanti M., E-mail: neny.rasnyanti@gmail.com; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm{sup −1} which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese

  20. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    Science.gov (United States)

    Aras, Neny Rasnyanti M.; Arcana, I. Made

    2015-09-01

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm-1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese stearate

  1. HDPE/r-PET原位微纤物微观形态与力学性能%Micromorphology and Mechanical Properties of HDPE/r-PET In-Situ Microfibrillar Blends

    Institute of Scientific and Technical Information of China (English)

    刘伟东; 王益龙; 杨博瀚; 吕悦

    2011-01-01

    以高密度聚乙烯(HDPE)和回收聚对苯二甲酸乙二醇酯(r-PET)为原料,通过反应挤出、冷拉伸、退火工艺制备了HDPE/r-PET原位微纤物.研究了扫描电镜(SEM)的制样方法即用液氮冷冻、脆断样品、聚四氟乙烯带包覆、在沸腾的二甲苯中刻蚀7~10 min和不同r-PET用量、不同拉伸比制备出的系列HDPE/r-PET原位微纤物的力学性能.结果表明,通过SEM可清晰地看到形成的微纤,原位微纤物的拉伸强度和冲击强度都随拉伸比的增大而增大;r-PET质量分数为15%时,原位微纤物的拉伸强度和无缺口冲击强度达到最大值;HDPE/r-PET原位微纤物的适宜注塑温度为210℃.%High density polyethylene(HDPE)/recycled poly(ethylene terephthalate) (r-PET) in-situ microfibrillar blends based on HDPE/r-PET were prepared by HDPE and r-PET as raw material through reactive extrusion-cold drawing and annealing. The preparing sample methed for scanning electron microscopy(SEM) was studied in detail, namely, the brittle samples frozen in liquid nitrogen, coated with Teflon tape and etched in boiling xylene for 7 -10 minutes. The mechanical properties of a series of HDPE/r-PET in-situ microfibrillar blends prepared through different r-PET content and different draw ratio were studied. The results show that the microfibrils can be seen clearly through SEM. The greater the draw ratio, the larger the tensile strength and impact strength of in-situ microfibrillar blends. The impact strength achieves the maximum when the mass fraction of r-PET is 15%. The suitable injection molding temperature for HDPE/r-PET in-situ microfibrillar blends is 210 'C.

  2. Riqueza e densidade de aves que nidificam em cavidades em plantações abandonadas de eucalipto

    Directory of Open Access Journals (Sweden)

    Hugo de Siqueira Pereira

    2015-05-01

    Full Text Available Monoculturas de árvores, como as de espécies de eucalipto, têm substituído florestas naturais, impactando a fauna pela perda de habitat e recursos. Diversas espécies de aves necessitam de ocos em árvores para nidificar. A falta de recursos como cavidades formadas pela degradação da árvore ou locais apropriados para serem criadas cavidades leva a diminuição na abundância das populações destas espécies. Este trabalho tem o objetivo de comparar a riqueza e a densidade de aves que nidificam em ocos em áreas de plantação de eucalipto abandonadas com áreas de vegetação nativa em duas unidades de conservação em Minas Gerais. Em cada tipo de vegetação de cada reserva foram estabelecidos 25 pontos, nas quais foi utilizado o método de contagem por remoção para o levantamento das espécies de aves. A riqueza de espécies de aves de cada área foi estimada por Jackniffe e a densidade foi estimada através do método de máxima verossimilhança; modelos candidatos que poderiam influenciar a abundância das aves foram avaliados utilizando-se o Critério de Informação Akaike (AIC. Os resultados mostraram que a riqueza de espécies foi maior nas áreas de florestas nativas e que a densidade foi significantemente mais alta nas áreas de florestas nativas, e que o tipo de vegetação e a hora do dia influenciam na abundância e detecção das aves. Esses resultados indicam que as plantações de eucaliptos influenciam negativamente a comunidade de aves que nidificam em ocos, provavelmente por causa da falta de cavidades ou de sub-bosque. Plantações de eucaliptos normalmente não substituem as florestas nativas e seu uso deve ser controlado em áreas de conservação.

  3. Development of a high density fuel based on uranium-molybdenum alloys with high compatibility in high temperatures; Desenvolvimento de um combustivel de alta densidade a base das ligas uranio-molibdenio com alta compatibilidade em altas temperaturas

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fabio Branco Vaz de

    2008-07-01

    This work has as its objective the development of a high density and low enriched nuclear fuel based on the gamma-UMo alloys, for utilization where it is necessary satisfactory behavior in high temperatures, considering its utilization as dispersion. For its accomplishment, it was started from the analysis of the RERTR ('Reduced Enrichment for Research and Test Reactors') results and some theoretical works involving the fabrication of gamma-uranium metastable alloys. A ternary addition is proposed, supported by the properties of binary and ternary uranium alloys studied, having the objectives of the gamma stability enhancement and an ease to its powder fabrication. Alloys of uranium-molybdenum were prepared with 5 to 10% Mo addition, and 1 and 3% of ternary, over a gamma U7Mo binary base alloy. In all the steps of its preparation, the alloys were characterized with the traditional techniques, to the determination of its mechanical and structural properties. To provide a process for the alloys powder obtention, its behavior under hydrogen atmosphere were studied, in thermo analyser-thermo gravimeter equipment. Temperatures varied from the ambient up to 1000 deg C, and times from 15 minutes to 16 hours. The results validation were made in a semi-pilot scale, where 10 to 50 g of powders of some of the alloys studied were prepared, under static hydrogen atmosphere. Compatibility studies were conducted by the exposure of the alloys under oxygen and aluminum, to the verification of possible reactions by means of differential thermal analysis. The alloys were exposed to a constant heat up to 1000 deg C, and their performances were evaluated in terms of their reaction resistance. On the basis of the results, it was observed that ternary additions increases the temperatures of the reaction with aluminum and oxidation, in comparison with the gamma UMo binaries. A set of conditions to the hydration of the alloys were defined, more restrictive in terms of temperature, time and pre-treatment to stabilize the gamma structure. The addition of a bit low ternary excess and formation of an intergranular phase, the increase in stability, it was demonstrated that there is not a damage in the formation of their powders.(author)

  4. Effect of coupling agent on nano-ZnO modification and antibacterial activity of ZnO/HDPE nanocomposite films

    Science.gov (United States)

    Li, Y. N.; Xu, W. M.; Zhang, G. Q.

    2015-07-01

    Commercial zinc oxide nanoparticles were modified by silane coupling agent of KH550 and KH560, respectively. The obtained nanocomposite was characterized by scanning electron microscopy (SEM), Thermogravimetric analyses (TGA) and apparent sedimentation stability (Sapp). Then, nano-ZnO/high-density polyethylene (HDPE) composite films were prepared via melt blending and a hot compression-molding process. The antibacterial testing of the films against E. coli and S. aureus was carried out via plate counting. SEM, TGA and Sapp suggest the modifier of silane changed the surface hydrophilicity and effectively broke the agglomerations of nanoparticles. Antibacterial testing results indicated the antibacterial rate of the films increased with increasing nano-ZnO content. At a low doped content of 0.2 wt%, the types of coupling agent influenced the antibacterial property with that of KH560-modified nano-ZnO/HDPE KH550-modified nano-ZnO/HDPE unmodified nano-ZnO/HDPE films. When the dosage nano-ZnO was over 0.2 wt%, the differences of antibacterial activity resulted by modification was concealed by the strong antibacterial activity with near 100% of the nano- ZnO/HDPE composite films.

  5. Preparation and characterization of electron-beam treated HDPE composites reinforced with rice husk ash and Brazilian clay

    Science.gov (United States)

    Ortiz, A. V.; Teixeira, J. G.; Gomes, M. G.; Oliveira, R. R.; Díaz, F. R. V.; Moura, E. A. B.

    2014-08-01

    This work evaluates the morphology, mechanical and thermo-mechanical properties of high density polyethylene (HDPE) composites. HDPE reinforced with rice husk ashes (80:20 wt%), HDPE reinforced with clay (97:3 wt%) and HDPE reinforced with both rice husk ashes and clay(77:20:3 wt%) were obtained. The Brazilian bentonite chocolate clay was used in this study. This Brazilian smectitic clay is commonly used to produce nanocomposites. The composites were produced by melting extrusion process and then irradiation was carried out in a 1.5 MeV electron-beam accelerator (room temperature, presence of air). Comparisons using the irradiated and non-irradiated neat polymer, and the irradiated and non-irradiated composites were made. The materials obtained were submitted to tensile, flexural and impact tests. Additionally HDT, SEM and XRD analyses were carried out along with the sol-gel analysis which aimed to assess the cross-linking degree of the irradiated materials. Results showed great improvement in most HDPE properties and a high cross-linking degree of 85% as a result of electron-beam irradiation of the material.

  6. Espaçamento, densidade populacional e adubação nitrogenada na cultura do milho Row spacing, population density and nitrogen fertilization in maize

    OpenAIRE

    José Pedro Ribeiro do Amaral Filho; D. FORNASIERI FILHO; Rogerio Farinelli; José Carlos Barbosa

    2005-01-01

    A distribuição espacial de plantas por área é um recurso para aumentar a produtividade. Para materiais de alta produtividade, são necessárias mais informações quanto à resposta à adubação nitrogenada. Assim, avaliou-se na cultura do milho a influência do espaçamento, da densidade populacional e de doses de nitrogênio no teor de nitrogênio nas folhas, estimativa do teor de clorofila, número de grãos por espiga, massa de 1.000 grãos, produtividade e teor de proteína nos grãos. O trabalho foi in...

  7. Seleção de progênies S0:1 de milho em diferentes densidades de semeadura Selection of S0:1 maize progenies under different plant densities

    Directory of Open Access Journals (Sweden)

    André Gustavo Steola

    2006-01-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito da densidade de semeadura sobre o processo de seleção de progênies endogâmicas S0:1 de milho. Utilizaram-se 98 progênies S0:1 derivadas do híbrido simples GNZ 2004, avaliadas em duas densidades de semeadura (50 mil e 75 mil plantas ha-1 . Em cada densidade foram avaliadas as 98 progênies S0:1, juntamente com o híbrido GNZ 2004 e sua geração F2. O delineamento utilizado em ambas as densidades foi o látice simples 10 x 10, com duas repetições. Os experimentos foram desenvolvidos em área experimental do Departamento de Agricultura da Universidade Federal de Lavras, em Lavras (MG. As características avaliadas foram produtividade de espigas despalhadas e prolificidade. Pelos resultados obtidos constatou-se variabilidade genética entre as progênies S0:1 nas duas densidades avaliadas, havendo a possibilidade de seleção de progênies com maior potencial de produção de espigas despalhadas. A não-significância da interação entre as progênies S0:1 e as densidades de semeadura associadas às altas correlações genéticas obtidas evidenciam que a seleção poderá ser realizada em qualquer uma das duas densidades, sem comprometer o processo seletivo.The present work aimed to evaluate the effect of planting density on the selection of inbred progenies. GNZ 2004 single hybrid, its F2 generation and ninety-eight S0:1 progenies were evaluated in two plant densities, 50 thousand and 75 thousand plants ha-1in a simple 10x10 lattice design. The experiment was performed in the experimental area of the Agriculture Department of the Universidade Federal de Lavras, in Lavras, Minas Gerais State, Brazil. Yield of husked ear and prolificy were evaluated. Results showed genetic variation among the S0:1 progenies in the two densities, allowing the selection of progenies with higher potential for production of husked ear corn. Interaction of the progenies x densities was not significant that

  8. HDPE/LLDPE blend-based nanocomposites - Part I: evaluation of thermo-mechanical properties and weathering resistance; Nanocompositos de blendas HDPE/LLDPE e OMMT - parte I: avaliacao das propriedades termo-mecanicas e da resistencia ao intemperismo

    Energy Technology Data Exchange (ETDEWEB)

    Passador, Fabio R.; Backes, Eduardo H.; Travain, Daniel R.; Ruvolo Filho, Adhemar; Pessan, Luiz A., E-mail: fabiopassador@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2013-07-01

    Nano composites from high density polyethylene/ linear low density polyethylene (HDPE/LLDPE) blends were prepared at the melt state in an extruder, using HDPE-g-MA as compatibilizer agent. The structural characterization was performed through wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The results showed that adding the compatibilizer induced formation of a predominant intercalated microstructure. Dynamic-mechanical studies showed that the addition of the compatibilizer increases the interactions between the nano clay surface and the polyolefin matrix. The weathering conditions affected the mechanical behavior of HDPE/LLDPE blend-based nano composites. Both treatments performed in hot water and in a forced convection air oven provided the relief of residual stresses in the polymer matrix, while the treatment in an accelerated aging chamber provided the formation of carbonyl groups that lead to a decreased degree of crystallinity and elastic modulus of the nanocomposites. (author)

  9. Influence of the surfactant in the shear-induced crystallization kinetics of HDPE/MMT nano composites; Influencia do tratamento superficial da montmorilonita na cinetica de cristalizacao induzida por fluxo de nanocompositos de HDPE

    Energy Technology Data Exchange (ETDEWEB)

    Bonel, A.B. [Universidade Federal de Sao Carlos (DEMA/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais; Beatrice, C.A.G.; Marini, J.; Bretas, R.E.S., E-mail: bretas@ufscar.b [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    High-density polyethylene (HDPE) compatibilized with ethylene vinyl-acetate copolymer (EVA)r, with 5 wt% of two different organically modified montmorillonite (with polar and non-polar surfactant) were prepared by melt blending in a corrotational twin-screw extruder at 225 deg C, 100rpm and 3kg/h. Both nanocomposites were characterized by wide-angle x-ray scattering (WAXS), transmission electron microscopy (TEM) and rheological measurements. The nanoclay's lamellas were intercalated in both samples. The storage and the loss moduli of the nanocomposites, at low frequencies, showed that the particles of the nanoclay modified with a polar surfactant were well dispersed thru the HDPE matrix, while the particles of the other nanoclay were well distributed thru the matrix. The presence of a nanoclay modified with a non-polar surfactant reduced the induction times for the crystals growth, due to the strong interactions with the HDPE chains. (author)

  10. Structural characterization of HDPE/LLDPE blend-based nano composites obtained by different blending sequence; Caracterizacao estrutural de nanocompositos de blendas HDPE/LLDPE obtidos por diferentes sequencias de misturas

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The blending sequence affects the morphology formation of the nanocomposites. In this work, the blending sequences were explored to determine its influence in the rheological behavior of HDPE/LLDPE/OMMT nanocomposites. The nanocomposites were obtained by melt-intercalation using a mixture of LLDPE-g-MA and HDPE-g-MA as compatibilizer system in a torque rheometer at 180 deg C and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where LLDPE and/or LLDPE-g-MA were first reinforced with organoclay since the intercalation process occurs preferentially in the amorphous phase. (author)

  11. Installing a HDPE vertical containment and collection system in one pass utilizing a deep trencher

    Energy Technology Data Exchange (ETDEWEB)

    Bocchino, W.M. [Groundwater Control Inc., Jacksonville, FL (United States); Burson, B. [Groundwater Control, Houston, TX (United States)

    1997-12-31

    A unique method has been developed to install high density polyethylene (HDPE) vertical containment panels and a horizontal collection system for the containment and collection of contaminated groundwater. Unlike other means of creating this type of system, this barrier wall and collection system is installed in one step and in one narrow trench, utilizing a one-pass deep trencher. Originally HDPE vertical barriers were installed using conventional slurry trenching techniques. Use of this method raised questions of trench stability and disposal costs for the trench spoils. In addition, if a collection system was desired, a separate trench or vertical wells were required. In response to these concerns, a trenchless vibratory installation method was developed. Although this method addressed the concerns of trench stability and disposal costs, it raised a whole new set of concerns dealing with drivable soil conditions, buried debris and obstructions. Again, if a collection system was desired, a separate trench or vertical wells had to be installed. The latest development, the one-pass, deep trencher, has eliminated or significantly reduced the previously discussed construction concerns. The trencher methods reduce the amount of spoils generated because a trench width of 61 cm (24 inches) is constantly maintained by the machine. Additionally, soil classification and density are not as critical as with a vibratory installation. This is due to the trencher`s ability to trench in all but the hardest of materials (blow counts exceeding 35 blows/ft). Finally, the cost to add a collection system adjacent to the cutoff wall is substantially reduced and is limited only to the cost of the additional hydraulic fill and 4 inches HDPE collection piping. The trench itself is already constructed with the installation of the wall.

  12. Effect of Silane Crosslinker on the Thermal Properties of Rice Straw/HDPE Biocomposite

    Directory of Open Access Journals (Sweden)

    W.A.W. A. Rahman

    2009-01-01

    Full Text Available A formulation was designed to produce silane crosslinkable rice straw/high density polyethylene (RSPE compound suitable for injection molding process. The formulations consist of high density polyethylene (HDPE as the base polymer, rice straw as the filler, processing aids and a mixture of crosslink chemicals. Crosslink chemicals consist of vinyltrimethoxysilane (VTMO as crosslinking agent, dicumyl peroxide (DCP as the initiator, dibutyltin dilaurate (DBTL as the condensation catalyst. Lignocellulosic material, rice straw was oven dried at 70°C for 24 h, grinded and sieved. A counter rotating twin shaft high speed mixer was utilized to mix the rice straw, HDPE and the processing aids. Blends were then compounded on co-rotating and intermeshing twin screw extruder. Test specimens were prepared via injection molding process followed by oven curing at 90°C. Fourier Transform Infra Red (FTIR was used to determine the chemical group involved in the crosslinking reaction. Degree of crosslinking in the silane crosslinked compound was measured by determining their gel content. Thermal properties were analyzed on the Differential Scanning Calorimetry (DSC for the melt temperature, Tm, whereas Thermogravimetric (TGA analysis for its thermal stability behavior. The degree of crosslinking in RSPE increases with an increased in VTMO and DCP concentration. The results from FTIR showed the presence of Si-O-Si bond and Si-O-C indicative of crosslinks formation. Thermal behavior of the compound illustrated that the crosslinked RSPE was more stable than the uncrosslinked RSPE and pure HDPE, while the Tm was unchanged.

  13. Installing a HDPE vertical containment and collection system in one pass utilizing a deep trencher

    International Nuclear Information System (INIS)

    A unique method has been developed to install high density polyethylene (HDPE) vertical containment panels and a horizontal collection system for the containment and collection of contaminated groundwater. Unlike other means of creating this type of system, this barrier wall and collection system is installed in one step and in one narrow trench, utilizing a one-pass deep trencher. Originally HDPE vertical barriers were installed using conventional slurry trenching techniques. Use of this method raised questions of trench stability and disposal costs for the trench spoils. In addition, if a collection system was desired, a separate trench or vertical wells were required. In response to these concerns, a trenchless vibratory installation method was developed. Although this method addressed the concerns of trench stability and disposal costs, it raised a whole new set of concerns dealing with drivable soil conditions, buried debris and obstructions. Again, if a collection system was desired, a separate trench or vertical wells had to be installed. The latest development, the one-pass, deep trencher, has eliminated or significantly reduced the previously discussed construction concerns. The trencher methods reduce the amount of spoils generated because a trench width of 61 cm (24 inches) is constantly maintained by the machine. Additionally, soil classification and density are not as critical as with a vibratory installation. This is due to the trencher's ability to trench in all but the hardest of materials (blow counts exceeding 35 blows/ft). Finally, the cost to add a collection system adjacent to the cutoff wall is substantially reduced and is limited only to the cost of the additional hydraulic fill and 4 inches HDPE collection piping. The trench itself is already constructed with the installation of the wall

  14. Assessment of NDE Methods to Detect Lack of Fusion in HDPE Butt Fusion Joints

    International Nuclear Information System (INIS)

    Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, were conducted to evaluate nondestructive examinations (NDE) coupled with mechanical testing of butt fusion joints in high-density polyethylene (HDPE) pipe for assessing lack of fusion. The work provided information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques of HDPE butt fusion joints in Section III, Division 1, Class 3, buried piping systems in nuclear power plants. This paper describes results from assessments using ultrasonic and microwave nondestructive techniques and mechanical testing with the high-speed tensile impact test and the side-bend test for determining joint integrity. A series of butt joints were fabricated in 3408, 12-inch (30.5-cm) IPS DR-11 HDPE material by varying the fusion parameters to create good joints and joints containing a range of lack-of-fusion conditions. Six of these butt joints were volumetrically examined with time-of-flight diffraction (TOFD), phased-array (PA) ultrasound, and the Evisive microwave system. The outer diameter (OD) weld beads were removed for microwave evaluation and the pipes ultrasonically re-evaluated. In two of the six pipes, both the outer and inner diameter (ID) weld beads were removed and the pipe joints re-evaluated. Some of the pipes were sectioned and the joints destructively evaluated with the high-speed tensile test and the side-bend test. The fusion parameters, nondestructive and destructive evaluation results have been correlated to validate the effectiveness of what each NDE technology detects and what each does not detect. There was no single NDE method that detected all of the lack-of-fusion flaws but a combination of NDE methods did detect most of the flaws.

  15. Surface Cleaning Techniques: Ultra-Trace ICP-MS Sample Preparation and Assay of HDPE

    Energy Technology Data Exchange (ETDEWEB)

    Overman, Nicole R.; Hoppe, Eric W.; Addleman, Raymond S.

    2013-06-01

    The world’s most sensitive radiation detection and assay systems depend upon ultra-low background (ULB) materials to reduce unwanted radiological backgrounds. Herein, we evaluate methods to clean HDPE, a material of interest to ULB systems and the means to provide rapid assay of surface and bulk contamination. ULB level material and ultra-trace level detection of actinide elements is difficult to attain, due to the introduction of contamination from sample preparation equipment such as pipette tips, sample vials, forceps, etc. and airborne particulate. To date, literature available on the cleaning of such polymeric materials and equipment for ULB applications and ultra-trace analyses is limited. For these reasons, a study has been performed to identify an effective way to remove surface contamination from polymers in an effort to provide improved instrumental detection limits. Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) was utilized to assess the effectiveness of a variety of leachate solutions for removal of inorganic uranium and thorium surface contamination from polymers, specifically high density polyethylene (HDPE). HDPE leaching procedures were tested to optimize contaminant removal of thorium and uranium. Calibration curves for thorium and uranium ranged from 15 ppq (fg/mL) to 1 ppt (pg/mL). Detection limits were calculated at 6 ppq for uranium and 7 ppq for thorium. Results showed the most effective leaching reagent to be clean 6 M nitric acid for 72 hour exposures. Contamination levels for uranium and thorium found in the leachate solutions were significant for ultralow level radiation detection applications.

  16. Surface cleaning techniques. Ultra-trace ICP-MS sample preparation and assay of HDPE

    International Nuclear Information System (INIS)

    The world's most sensitive radiation detection and assay systems depend upon ultra-low-background (ULB) materials to reduce unwanted radiological backgrounds. In this study, we evaluate methods to clean HDPE, a material of interest to ULB systems and the means to provide rapid assay of surface and bulk contamination. ULB-level material and ultra-trace-level detection of actinide elements is difficult to attain, due to the introduction of contamination from sample preparation equipment such as pipette tips, sample vials, forceps, etc and airborne particulate. To date, literature available on the cleaning of such polymeric materials and equipment for ULB applications and ultra-trace analyses is limited. For these reasons, a study has been performed to identify an effective way to remove surface contamination from polymers in an effort to provide improved instrumental detection limits. Inductively Coupled Plasma Mass Spectroscopy was utilized to assess the effectiveness of a variety of leachate solutions for removal of inorganic uranium and thorium surface contamination from polymers, specifically high density polyethylene (HDPE). Leaching procedures for HDPE were tested to optimize contaminant removal of thorium and uranium. Calibration curves for thorium and uranium ranged from 15 ppq (fg/mL) to 1 ppt (pg/mL). Detection limits were calculated at 6 ppq for uranium and 7 ppq for thorium. Results showed the most effective leaching reagent to be clean 6 M nitric acid for 72 h exposures. Contamination levels for uranium and thorium found in the leachate solutions were significant for ultra-low-level radiation detection applications. (author)

  17. Elongational viscometry and bubble inflation experiments of two HDPE materials with different molecular structures, S. Eggen, A. Malmberg, P. Vainikka, E. Hinrichsen, H.K. Rasmussen

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Eggen, Svein; Malmberg, Anneli;

    2002-01-01

    The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc.......The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc....

  18. Structure and Properties of HDPE/Nano-OMMT Composite by Dynamic Packing Injection Molding%动态保压注射成型HDPE/Nano-OMMT复合材料的结构与性能

    Institute of Scientific and Technical Information of China (English)

    胡娟; 王中武; 严山明; 高雪芹; 邓聪; 张杰; 申开智

    2011-01-01

    聚合物/黏土纳米复合材料是近几年聚合物材料改性的热点.为了进一步理解复合材料性能与结构的关系,利用自行研制的动态保压装置,借助WAXD、DSC、SEM等测试方法,研究了高密度聚乙烯(HDPE)/纳米有机蒙脱土(nano-OMMT)复合材料的结构与性能.结果表明,动态保压使OMMT纳米粒子在基体中的分散性提高,并形成插层结构.与此同时,动态剪切力场使HDPE/nano-OM MT复合材料的HDPE基体结构形态亦发生变化,试样中生成串晶结构,相比常规注塑试样,动态保压试样结晶度最大提高15%,结晶形态的变化和结晶度的提高均有利于HDPE/nano-OMMT复合材料强度的提高.力学性能试验显示,拉伸强度和冲击强度同时得到提高,HDPE/nano-OMMT复合试样的拉伸强度最大提高了119%,冲击强度最大提高430%.%Polymer/clay nano-composites were extensively explored in recent years. For better understanding the relationship between structure and property of polymer material, in this paper, structure and property of HDPE/nano-OMMT composites were discussed prepared by a self-made dynamic packing injection molding (DPIM) device by WAXD, DSC and SEM. Results showed that the dispersion of nano-OMMT was exclusively improved and formed intercalated structure. On the other hand, The formation of shish-kebab was also detected in dynamic HDPE/nano-OMMT composites. Compared with conventional injection molding, the crystallinity of dynamic packing HDPE/nano-OMMT was increased by 15% , which was facilitated to improve the strength of HDPE/nano-OMMT composites. Mechanical test demonstrated both tensile strength and impact strength enhanced. In addition, the maximum increase of tensile strength and impact strength were 119% , 430% , respectively.

  19. Quasi-Static and High Strain Rate Compressive Response of Injection-Molded Cenosphere/HDPE Syntactic Foam

    Science.gov (United States)

    Bharath Kumar, B. R.; Singh, Ashish Kumar; Doddamani, Mrityunjay; Luong, Dung D.; Gupta, Nikhil

    2016-07-01

    High strain rate compressive properties of high-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10-4 s-1, 10-3 s-1 and 10-2 s-1 strain rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10-4 s-1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.

  20. Influence of the surfactant in the shear-induced crystallization kinetics of HDPE/MMT nano composites

    International Nuclear Information System (INIS)

    High-density polyethylene (HDPE) compatibilized with ethylene vinyl-acetate copolymer (EVA)r, with 5 wt% of two different organically modified montmorillonite (with polar and non-polar surfactant) were prepared by melt blending in a corrotational twin-screw extruder at 225 deg C, 100rpm and 3kg/h. Both nanocomposites were characterized by wide-angle x-ray scattering (WAXS), transmission electron microscopy (TEM) and rheological measurements. The nanoclay's lamellas were intercalated in both samples. The storage and the loss moduli of the nanocomposites, at low frequencies, showed that the particles of the nanoclay modified with a polar surfactant were well dispersed thru the HDPE matrix, while the particles of the other nanoclay were well distributed thru the matrix. The presence of a nanoclay modified with a non-polar surfactant reduced the induction times for the crystals growth, due to the strong interactions with the HDPE chains. (author)

  1. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    International Nuclear Information System (INIS)

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  2. HDPE/LLDPE blend-based nanocomposites - Part I: evaluation of thermo-mechanical properties and weathering resistance

    International Nuclear Information System (INIS)

    Nano composites from high density polyethylene/ linear low density polyethylene (HDPE/LLDPE) blends were prepared at the melt state in an extruder, using HDPE-g-MA as compatibilizer agent. The structural characterization was performed through wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The results showed that adding the compatibilizer induced formation of a predominant intercalated microstructure. Dynamic-mechanical studies showed that the addition of the compatibilizer increases the interactions between the nano clay surface and the polyolefin matrix. The weathering conditions affected the mechanical behavior of HDPE/LLDPE blend-based nano composites. Both treatments performed in hot water and in a forced convection air oven provided the relief of residual stresses in the polymer matrix, while the treatment in an accelerated aging chamber provided the formation of carbonyl groups that lead to a decreased degree of crystallinity and elastic modulus of the nanocomposites. (author)

  3. Characteristic study of pre-irradiated HDPE grafted with NIPA/AAc

    International Nuclear Information System (INIS)

    HDPE preirradiated under nitrogen protection was grafted with NIPA/AAc. The grafted hydrogel is temperature and pH sensitive. FTIR, DSC, SEM were used to study the composition, properties and surface morphology of the hydrogel. Results showing that LCST characteristics was different under different pH environment. Under acid condition, hydrogel volume increased with increasing temperature, indicating the hydrogel being heat expansive and temperature sensitive. Under neutral or alkaline condition, hydrogel volume contracted rapidly near phase transition with increasing temperature, indicating the hydrogel being heat shrinking and temperature sensitive. (authors)

  4. Surface treatment of high density polyethylene (HDPE film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    Directory of Open Access Journals (Sweden)

    Joshi Ujjwal Man

    2015-03-01

    Full Text Available Thin films of high density polyethylene (HDPE are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. HDPE samples before and after the treatment are studied using contact angle measurements, surface free energy calculations and atomic force microscopy (AFM. Distilled water (H2O, glycerol (C3H8O3 and diiodomethane (CH2I2 are used as test liquids. The contact angle measurements between test liquids and HDPE samples are used to determine total surface free energy using sessile drop technique. HDPE films show a remarkable increase in surface free energy after plasma treatment. AFM analysis of the plasma-treated HDPE films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  5. A kinetic analysis of the melting HA/Y-PSZ/HDPE nano bio composite for hard tissue materials

    OpenAIRE

    Jha, A.; Kashan, JS; Thamir, AD; Al-Haidary, JT

    2016-01-01

    Melting characteristics of high-density polyethylene (HDPE) mixed with nano-size ceramic fillers (hydroxyl apatite and yttria stabilised zirconia) was analysed using the isochronal heating rate between 10 C min 1 and 80 C min 1. In this investigation, the kinetics of melting of HDPEceramic composites was analysed using the Avrami equation and the Kissinger model, applied to the Avrami formalism. The magnitude of the apparent energy barrier for the melting of HDPE falls within a range of 12 kJ ...

  6. Alta Capital investeerib miljardeid kroone / Raigo Neudorf

    Index Scriptorium Estoniae

    Neudorf, Raigo

    2006-01-01

    Investeerimisfirma Alta Capital nõukogu esimees Indrek Rahumaa annab ülevaate sellest, kuidas ettevõte on lühikese ajaga suutnud omandada osaluse mitmetes ettevõtetes ning suunanud neisse investeeringuid 150 miljoni euro väärtuses. Vt. samas: Osalused; Omanikud

  7. Migration of residual nonvolatile and inorganic compounds from recycled post-consumer PET and HDPE

    Energy Technology Data Exchange (ETDEWEB)

    Dutra, Camila; Reyes, Felix G.R., E-mail: reyesfgr@fea.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Escola de Engenharia dos Alimentos. Dept. de Ciencias dos Alimentos; Freire, Maria Teresa de A. [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Fac. de Ciencia Animal e Engenharia dos Alimentos. Dept. de Engenharia dos Alimentos; Nerin, Cristina; Bentayeb, Karim; Rodriguez-Lafuente, Angel; Aznar, Margarita [Dept. of Analytical Chemistry, Arago Inst. of Engineering Research, University of Zaragoza (Spain)

    2014-04-15

    Migration of nonvolatile and inorganic residual compounds from post-consumer recycled polyethylene terephthalate (PET) submitted to cleaning processes for subsequent production of materials intended to food contact, as well as from multilayer packaging material containing post-consumer recycled high-density polyethylene (HDPE) was determined. Tests were carried out using food simulant. Nonvolatile organic contaminants from PET, determined by liquid chromatography-mass spectrometry (UPLC-QqQ/MS), showed significant migration reduction as consequence of the more complex cleaning technologies applied. However, contaminants not allowed by Brazilian and European Union regulations were identified even in deep cleaning samples. Results from multilayer HDPE showed a greater number of contaminants when compared to recycled pellets. Inorganic contaminants, determined by inductively coupled plasma mass spectrometry were below the acceptable levels. Additional studies for identification and quantitation of unknown molecules which were not possible to identify in this study by UPLC-QqQ/MS are required to ascertain the safety of using post-consumer recycled packaging material. (author)

  8. HDPE (High Density Polyethylene) pipeline and riser design in Guanabara Bay: challenges and solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bomfimsilva, Carlos; Jorge, Joao Paulo Carrijo; Schmid, Dominique; Gomes, Rodrigo Klim [INTECSEA, Sao Paulo, SP (Brazil); Lima, Alexander Piraja [GDK, Salvador, BA (Brazil)

    2009-12-19

    Worldwide shipments of plastic pipes are forecasted to increase 5.2% per year since 2008, being commonly used for water supply and sewage disposal. The HDPE (High Density Polyethylene) pipes have been applied recently to deliver potable water and fire fighting water for the main pier of the LNG system in Guanabara Bay, Rio de Janeiro. The system contains three sizes of pipe outside diameter, 110 mm and 160 mm for water supply, and 500 mm for the fire fighting system. The main design challenges of the pipeline system included providing on-bottom stability, a suitable installation procedure and a proper riser design. The on-bottom stability calculations, which are quite different from the conventional steel pipelines, were developed by designing concrete blocks to be assembled on the pipeline in a required spacing to assure long term stability, knowing that plastic pipes are buoyant even in flooded conditions. The installation procedure was developed considering the lay down methodology based on surface towing technique. The riser was designed to be installed together with additional steel support structure to allow the entire underwater system to have the same plastic pipe specification up to the surface. This paper presents the main challenges that were faced during the design of the HDPE pipelines for the LNG system in Guanabara Bay, addressing the solutions and recommendations adopted for the plastic underwater pipeline system.

  9. Effect of gamma irradiation on mechanical, thermal and rheological behavior of HDPE filled with seaweed residues

    Science.gov (United States)

    Cataño, L.; Albano, C.; Karam, A.; Domínguez, N.; Sánchez, Y.; González, J.

    2005-07-01

    The present work shows the results obtained during the investigation of the influence of gamma irradiation on mechanical, thermal and rheological properties of high-density polyethylene (HDPE) filled with seaweed residues (SR). The SR used was located on Venezuelan coastlines and they are composed mainly by CaCO3 in aragonite phase. The HDPE was extruded along with the filler at different compositions (20, 30 and 40 wt.%). The composites were exposed to a 60Co source irradiated at 25 and 100 kGy. From the obtained results, it was noticed that Young modulus remained constant with filler content. Moreover, the influence of filler content was found to be more prominent on properties like tensile stress and elongation at break. On the other hand, thermal analysis showed that filler content had no significant influence on thermal stability. Still, it is necessary to point out that low radiation doses improved thermal stability of the composites. From rheological studies it was observed a decreasing of melt flow index (MFI) by increasing the SR amount and radiation. Therefore, was determinate that high filler content composites are the best choice to be considered for biomedical and industrial applications.

  10. Migration of residual nonvolatile and inorganic compounds from recycled post-consumer PET and HDPE

    International Nuclear Information System (INIS)

    Migration of nonvolatile and inorganic residual compounds from post-consumer recycled polyethylene terephthalate (PET) submitted to cleaning processes for subsequent production of materials intended to food contact, as well as from multilayer packaging material containing post-consumer recycled high-density polyethylene (HDPE) was determined. Tests were carried out using food simulant. Nonvolatile organic contaminants from PET, determined by liquid chromatography-mass spectrometry (UPLC-QqQ/MS), showed significant migration reduction as consequence of the more complex cleaning technologies applied. However, contaminants not allowed by Brazilian and European Union regulations were identified even in deep cleaning samples. Results from multilayer HDPE showed a greater number of contaminants when compared to recycled pellets. Inorganic contaminants, determined by inductively coupled plasma mass spectrometry were below the acceptable levels. Additional studies for identification and quantitation of unknown molecules which were not possible to identify in this study by UPLC-QqQ/MS are required to ascertain the safety of using post-consumer recycled packaging material. (author)

  11. Effect of gamma irradiation on mechanical, thermal and rheological behavior of HDPE filled with seaweed residues

    International Nuclear Information System (INIS)

    The present work shows the results obtained during the investigation of the influence of gamma irradiation on mechanical, thermal and rheological properties of high-density polyethylene (HDPE) filled with seaweed residues (SR). The SR used was located on Venezuelan coastlines and they are composed mainly by CaCO3 in aragonite phase. The HDPE was extruded along with the filler at different compositions (20, 30 and 40 wt.%). The composites were exposed to a 60Co source irradiated at 25 and 100 kGy. From the obtained results, it was noticed that Young modulus remained constant with filler content. Moreover, the influence of filler content was found to be more prominent on properties like tensile stress and elongation at break. On the other hand, thermal analysis showed that filler content had no significant influence on thermal stability. Still, it is necessary to point out that low radiation doses improved thermal stability of the composites. From rheological studies it was observed a decreasing of melt flow index (MFI) by increasing the SR amount and radiation. Therefore, was determinate that high filler content composites are the best choice to be considered for biomedical and industrial applications

  12. y alta de la subcuenca Cohatán, Chiapas

    Directory of Open Access Journals (Sweden)

    M. Grajales

    2008-01-01

    Full Text Available El estudio consistió en un diagnóstico biofísico (fisiográfico, hidrográfico, uso actual del suelo, cobertura vegetal y socioeconómico (infraestructura social y productiva con actividades en la subcuenca Cohatán, localizado en las estribaciones de la Sierra del Soconusco Chiapas, para saber la situación que guarda y generar acciones de rehabilitación, a mediano y largo plazo. Esta subcuenca se extiende desde 350 a los 4,080 msnm, con 42 comunidades, que abarcan los municipios de Tapachula, Motozintla y Cacahotán, Chiapas; tiene una densidad de 1.2 hab/ha, con suelo de origen volcánico formado del Cenozoico terciario de unidad acrisol húmico. El 80% de la superficie presenta clima tropical húmedo y subhúmedo, con relieve de ladera fuerte hasta de 60%, con una erosión hídrica severa de 250 t/ ha/año en 42% de la superficie; tiene 25% de selva, medias altas y perennifolias. La principal actividad económica es la explotación del cultivo de café, desde el área marginal 350 hasta 2,660 msnm. A lo largo del río Cohatán el tipo de desarrollo se sustenta en el uso intensivo de los recursos naturales, originan —a su vez— fuerte deterioro neceambiental, al cambio de vegetación de la selva original por introducción de especies de sombra del café con chalum (Inga spp; en este ecosistema se observa un deficiente uso de tecnología de producción que se refleja en el bajo rendimiento del café, de 8 quintales/ha. El nivel socioeconómico de desarrollo es bajo, con nivel de educación, salud, vivienda y servicios deficientes, así como falta de apoyo social, con carente gestión ambiental

  13. IMPROVING THE PROPERTIES OF HDPE BASED SEPARATORS FOR LITHIUM ION BATTERIES BY BLENDING BLOCK WITH COPOLYMER PE-b-PEG

    Institute of Scientific and Technical Information of China (English)

    Jun-li Shi; Hao Li; Li-feng Fang; Zhi-ying Liang; Bao-ku Zhu

    2013-01-01

    To improve the performances of HDPE-based separators,polyether chains were incorporated into HDPE membranes by blending with poly(ethylene-block-ethylene glycol) (PE-b-PEG) via thermally induced phase separation (TIPS) process.By measuring the composition,morphology,crystallinity,ion conductivity,etc,the influence of PE-b-PEG on structures and properties of the blend separator were investigated.It was found that the incorporated PEG chains yielded higher surface energy for HDPE separator and improved affinity to liquid electrolyte.Thus,the stability of liquid electrolyte trapped in separator was increased while the interfacial resistance between separator and electrode was reduced effectively.The ionic conductivity of liquid electrolyte soaked separator could reach 1.28 × 10-3 S.cm-1 at 25℃,and the electrochemical stability window was up to 4.5 V (versus Li+/Li).These results revealed that blending PE-b-PEG into porous HDPE membranes could efficiently improve the performances of PE separators for lithium batteries.

  14. The Effects of Coupling Agents on the Mechanical and Thermal Properties of Eucalyptus Flour/HDPE Composite

    Directory of Open Access Journals (Sweden)

    Metanawin Siripan

    2015-01-01

    Full Text Available The aim of this research was to study the effects of the coupling agents, FusabondTM E-528 (polyethylene-grafted maleic anhydride; PE-g-MA, MA and Amino Silane (Si, on the thermal properties, and mechanical properties of Eucalyptus flour-HDPE composite. Variation of the Eucalyptus flour contents in the HDPE resulted in properties of the composite. With increasing in the contents of Eucalyptus flour in polymer matrix, the mechanical properties of the HDPE composite decreased in EU-MA series samples while they were gradually decreased in EU-Si series samples. SEM micrographs showed the fracture surface of the HDPE/Eucalyptus composite at different ratios of Eucalyptus flour. SEM micrograpgh exhibited the dispersion of EU flour in polymer matrix. The samples of both coupling agents showed an increase in interfacial adhesion, observed for the considerable decreased of gaps between the matrix and the dispersed phase. However, the EU-MA sample appeared to be more uniformly than the EU-Si sample.

  15. Measurement of heat capacity and thermal conductivity of HDPE/expanded graphite nanocomposites by differential scanning calorimetry

    Directory of Open Access Journals (Sweden)

    A. Ezan

    2011-07-01

    Full Text Available Purpose: In this study, heat capacity and thermal conductivity of nanocomposites formed by high density polyethylene (HDPE matrix and expanded graphite (EG conductive filling material were investigated.Design/methodology/approach: Nanocomposites containing up to 20 weight percent of expanded graphite filler material were prepared by mixing them in a Brabender Plasticorder. Two grades of expanded graphite fillers were used namely expanded graphite with 5 µm (EG5 and 50 µm (EG50 in diameter. Heat capacity and thermal conductivity of pure HDPE and the nanocomposites were measured using differential scanning calorimetry (DSC.Findings: A substantial increase in thermal conductivity was observed with the addition of expanded graphite to HDPE. Thermal conductivity increased from 0.442 W/m.K for pure HDPE to 0.938 W/m.K for nanocomposites containing 7% by weight of expended graphite. Heat capacity increases with the increase in temperature for both pure HDPE and the nanocomposites filled with expanded graphite and no appreciable difference in the values of heat capacity were detected due to particle size. Heat capacity decreased with increasing graphite particle content for both particle size, following the low of mixtures.Practical implications: Layers of expanded graphite have become of intense interest as fillers in polymeric nanocomposites. Upon mixing the expanded graphite intercalates and exfoliates into nanometer thickness sheets due to their sheet-like structure and week bonds normal to the graphite sheets. That way they have very big surface area and high aspect ratio (200−1500 what results in a formation of percolating network at very low filler content. The nanoparticles usage results in significant improvement in thermal, mechanical, and electrical properties of polymers even with very low loading levels compared with microparticles.Originality/value: To see the effect of conducting fillers on thermal conductivity and heat capacity two

  16. Kualitas Papan Komposit dari Sekam Padi dan Plastik HDPE Daur Ulang Menggunakan Maleic Anhydride (MAH sebagai Compatibilizer

    Directory of Open Access Journals (Sweden)

    Umi Fathanah

    2011-12-01

    Full Text Available The utilization of rice husk as raw material on preparation of composite board could be used as alternative and cheap construction material. In this research, the  composite board was prepared by mixing fined rice husk, recycledhigh density polyethylene (HDPE plastic. Maleic Anhydride (MAH was added ascompatibilizer. The objective of this research is to develop an alternative and a cheap technologyon fabrication of composite board by utilizing rice husk waste as filler and plastic from the type of recycled HDPE plastic as matrix. In order to improve the compactness of rice husk and recycled HDPE plastic thus the addition of MAH as compatibilizer is carried out. The research aspect learned is the MAH addition variation as much of 4% and 8% from HDPE plastic weight, and the mixing ratios of filler and matrix which are 30:70; 40:60; 50:50; 60:40; 70:30. Casting process of the homogonized solution was  carried out at casting temperature of 145oC for 20 minutes. The research result obtained indicates that the value of composite board density has fulfilled standard of SNI 03-2105-1996. The maximum water adsorbtion is obtained on composition of filler and matrixof 60:40 where with the addition of MAH 4% and 8% they are 10,1% and 6.9%, respectively. The addition of MAH as much of4% and 8% has resulted composite board with tensile strength value that has fulfilled SNI standard. Whereas the addition of MAH as much of 8% could increase modulus of rapture value of composite board i. e. 82.5 – 85.2 kgf/cm2and they have fulfilled standard of SNI 03-2105-1996. Keywords: Composite board, Maleic Anhydride (MAH, Recycled HDPE plastic, Tensile Strength, modulus of rapture.

  17. Equipament a la part alta de Tarragona

    OpenAIRE

    Padrós Tortares, Laura

    2010-01-01

    L'exercici proposa una solució de l'accessiblitat a nivell urbà del casc antic, al temps que l'edifici respon un equipament destinat a la població majoritaria resident de la part alta de tarragona. El projecte vol obrir i al mateix temps donar funcionalitat a una part de les runes del circ romà que se situen als baixos de l'edifici, incloent-los en l'equipament.

  18. Diffusione molecolare neLl' alta atmosfera

    Directory of Open Access Journals (Sweden)

    C. ARDUINI

    1963-06-01

    Full Text Available Le perturbazioni indotte nell'alta atmosfera dall'emissione,
    a mezzo di razzi sonda, di nubi di vapori estranei sono un utile
    mezzo per lo studio simultaneo di alcune caratteristiche fisiche e dinamiche
    degli alti strati.
    La presente relazione illustra in breve i principi di alcune tecniche
    per la misura del coefficiente di diffusione binaria tra l'aria e il vapore
    della nube artificiale.

  19. MEASUREMENT AND MODELLING OF SORPTION EQUILIBRIUM CURVE OF WATER ON PA6, PP, HDPE AND PVC BY USING FLORY-HUGGINS MODEL

    Directory of Open Access Journals (Sweden)

    Suherman Suherman

    2012-02-01

    Full Text Available The sorption of water on granular polyamide-6 (PA6, granular polypropylene (PP, and powdery high density polyethylene (HDPE and powdery polyvinyl chloride (PVC were measured using a gravimetric method in a magnetic suspension balance (MSB. The Flory-Huggins model was successfully applied on the sorption equilibrium curve of all investigated polymers. The influence of temperature is low. The value of Flory-Huggins parameters(c of PA6, PVC, PP and HDPE were 1.8, 5.8, 6.3, and 8.1, respectively. The water in PA6 is mainly bound moisture, while in PP, HDPE and PVC it is mainly surface moisture.

  20. TransAlta 2003 annual report

    International Nuclear Information System (INIS)

    This annual report presents financial information from TransAlta Corp., along with a review of its operations throughout 2003 and a summary of the how the electric utility has performed in terms of power generation, independent power producers, transmission and energy marketing. TransAlta is one of the largest non-regulated power generation and wholesale marketing companies in Canada. It's assets include coal-fired, gas-fired, hydro and renewable generation facilities in Canada, the United States, Mexico and Australia. Reported earnings in 2003 were $1.26 per share compared to $1.17 in 2002. The strong first quarter was followed by harsh market conditions, low water levels which affected hydro production, and pricing restrictions in Ontario that reduced contribution from the Sarnia plant. This report outlines the utility's progress in increasing revenue and producing more power. In 2003, unplanned outages were reduced by 7 per cent and injury frequency rate was reduced by 27 per cent. The installation of 114 wind turbines in Fort Macleod, Alberta, increased TransAlta's renewable energy capacity to 3.7 per cent in 2003. The wind farm produces 75 MW of electricity, enough to power more than 32,500 homes annually. This report summarized the company's energy resource activities and presented an operations review as well as consolidated financial statements and common share information. This included the utility's assets, liabilities, revenues, expenses and cash flows. Revenue and expenditure statements were summarized by source. refs., tabs., figs

  1. Analysis of surface degradation of high density polyethylene (HDPE) insulation material due to tracking

    Indian Academy of Sciences (India)

    R Sarathi; S Chandrasekar; V Sabari Giri; C Venkataseshaiah; R Velmurugan

    2004-06-01

    In the present work, tracking phenomena has been studied with HDPE material under a.c. voltage, with ammonium chloride as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The diffusion coefficient of the material was obtained. The thermal and chemical stability of the material were identified by carrying out a methodical experimental study. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), were carried out and it was concluded that the mechanism of tracking process is due to the surface degradation. The surface condition of the insulation structure was characterized for any surface discharges or tracking, using the leakage current measurement, utilizing the wavelet concepts.

  2. Influence of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE composites

    Science.gov (United States)

    Nobile, Maria Rossella; Somma, Elvira; Valentino, Olga; Simon, George; Neitzert, Heinz-Christoph

    2016-05-01

    Rheological and electrical properties of nanocomposites based on multi-walled carbon nanotubes (MWNTs) and high density polyethylene (HDPE), prepared by melt mixing in a micro-twin screw extruder, have been investigated. The effect of MWNT concentration (0.5 and 2.5 wt %) and nanotube surface treatment (oxidative treatment in a tubular furnace at 500°C for 1 hr in a 95% nitrogen, 5% oxygen atmosphere) has been analyzed. It has been found that the sample conductivity with oxidation of the nanotubes decreases more than 2 orders of magnitude. Scanning electron microscopy showed good adhesion and dispersion of nanotubes in the matrix, independently of the surface treatment. Electrical and rheological measurements revealed that the oxidative treatment, causing some reduction of the MWNT quality, decreases the efficiency of the nanotube matrix interaction.

  3. Post-{gamma}-irradiation reactions in vitamin E stabilised and unstabilised HDPE

    Energy Technology Data Exchange (ETDEWEB)

    Mallegol, J.; Carlsson, D.J. E-mail: dave.carlsson@nrc.ca; Deschenes, L

    2001-12-01

    The oxidation of high density polyethylene (HDPE), both unstabilised and vitamin E stabilised, has been studied by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies in the period following {gamma}-irradiation at doses from 1 to 60 kGy (range of food sterilisation). Derivatisation by reaction with sulphur tetrafluoride was used to identify macro-ketone and carboxylic acid components of the overlapped IR carbonyl region. Oxidation continued for several hundred hours after the cessation of irradiation as shown by the increase in hydroxyl, ketone and acid groups. Carboxylic acid groups are particularly important as a direct indication of backbone scission. Vitamin E, although an effective antioxidant during {gamma}-irradiation, was less effective in reducing the post-irradiation changes, which are probably driven by migration of radical sites along the polymer backbone from within the crystalline phase to the amorphous/crystalline inter-phase, where they become oxygen accessible.

  4. Post-/γ-irradiation reactions in vitamin E stabilised and unstabilised HDPE

    Science.gov (United States)

    Mallégol, J.; Carlsson, D. J.; Deschênes, L.

    2001-12-01

    The oxidation of high density polyethylene (HDPE), both unstabilised and vitamin E stabilised, has been studied by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies in the period following γ-irradiation at doses from 1 to 60 kGy (range of food sterilisation). Derivatisation by reaction with sulphur tetrafluoride was used to identify macro-ketone and carboxylic acid components of the overlapped IR carbonyl region. Oxidation continued for several hundred hours after the cessation of irradiation as shown by the increase in hydroxyl, ketone and acid groups. Carboxylic acid groups are particularly important as a direct indication of backbone scission. Vitamin E, although an effective antioxidant during γ-irradiation, was less effective in reducing the post-irradiation changes, which are probably driven by migration of radical sites along the polymer backbone from within the crystalline phase to the amorphous/crystalline inter-phase, where they become oxygen accessible.

  5. Post-γ-irradiation reactions in vitamin E stabilised and unstabilised HDPE

    International Nuclear Information System (INIS)

    The oxidation of high density polyethylene (HDPE), both unstabilised and vitamin E stabilised, has been studied by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies in the period following γ-irradiation at doses from 1 to 60 kGy (range of food sterilisation). Derivatisation by reaction with sulphur tetrafluoride was used to identify macro-ketone and carboxylic acid components of the overlapped IR carbonyl region. Oxidation continued for several hundred hours after the cessation of irradiation as shown by the increase in hydroxyl, ketone and acid groups. Carboxylic acid groups are particularly important as a direct indication of backbone scission. Vitamin E, although an effective antioxidant during γ-irradiation, was less effective in reducing the post-irradiation changes, which are probably driven by migration of radical sites along the polymer backbone from within the crystalline phase to the amorphous/crystalline inter-phase, where they become oxygen accessible

  6. HDPE/HA composites obtained in solution: Effect of the gamma radiation

    International Nuclear Information System (INIS)

    Radiation is employed to sterilize composite materials used in the biomedical field. Due to the changes induced by radiation onto polymeric materials, it is important to study variations in their melt flow index (MFI), as well as in their mechanical and thermal properties. In this work, those previous parameters were determined in composites obtained via solution of a high-density polyethylene (HDPE) in decalin, with different amounts of hydroxyapatite (HA), varying from 10 to 30 parts per hundred, after being exposed to gamma radiation at absorbed doses between 25 and 100 kGy. After the irradiation, the MFI of HDPE dissolved in decalin and precipitated afterwards and without filler increased from 6 to 24 g/10 min at the highest absorbed doses. This behavior was also observed in composites with 10 pph of HA, being the increase less pronounced, specifically in the range between 50 and 100 kGy. Composites with 20 and 30 pph of HA showed a maximum MFI value at 50 kGy, which decreased at higher doses. This implies that the filler begin to exert an influence because it does not melt at the test temperature and consequently, it does not flow. It was observed that Young's modulus increased with HA addition due to rigidity of the ceramic filler. Radiation did not significantly affect this tensile property. On the other hand, the tensile strength did not show significant variations at the different doses but the filler content did affect this property improving it. Finally, elongation at break showed a drastic decrease with filler addition. When the thermal behavior was studied it was noticed that crystallization and melting temperatures remained unchanged. Instead, crystallinity degree slightly increased in the composites, and a little decrease was obtained when they were irradiated

  7. Surface treatment of high density polyethylene (HDPE) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    OpenAIRE

    Joshi Ujjwal Man; Subedi Deepak Prasad

    2015-01-01

    Thin films of high density polyethylene (HDPE) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. HDPE samples before and after the treatment are studied using contact angle measurements, surface free energy calculations and atomic force microscopy (AFM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liqu...

  8. 加工工艺对HDPE/CaCO3共混体系性能的研究%Study of processing on properties of HDPE/CaCO3 blends

    Institute of Scientific and Technical Information of China (English)

    李清江

    2016-01-01

    采用偏光显微镜研究了4种不同加工工艺对改性HDPE结晶结构的影响,并且通过SEM分析方法研究了纳米CaCO3在HDPE基体中的分散特性.研究结果表明:在HDPE/CaCO3共混体系配方不变的情况下,加工工艺d更有利于提高纳米CaCO3粒子在HDPE基体中的最终分散性和HDPE/CaCO3共混体系的力学性能.

  9. Comportamiento viscoso de lubricantes e altas presiones

    OpenAIRE

    Paredes Méndez, Xavier

    2012-01-01

    Esta Tesis Doctoral se centra en el estudio del comportamiento viscoso a alta presión de diferentes lubricantes de tipo mineral, vegetal y sintético. Cinco líquidos analizados a lo largo de este trabajo pueden ser usados como materiales de referencia para la calibración de viscosímetros a presión: di (2-etilhexil) sebacato, di (2-etilhexil) ftalato, diisodecilftalato, escualano y dipentaeritritol hexaisononanoato. Además se estudian cinco bases sintéticas para sistemas de refrigeración con di...

  10. Aprendizaje cooperativo con alumnos de altas capacidades

    OpenAIRE

    Herrera Lara, Inmaculada

    2016-01-01

    El presente Trabajo Fin de Grado tiene como finalidad conocer e investigar la intervención educativa que se lleva a cabo con los alumnos de altas capacidades a través del aprendizaje cooperativo. Estos alumnos necesitan de la ayuda y colaboración de los otros para lograr verdaderos procesos de aprendizaje. Sin la colaboración de docentes, padres y demás organismos del centro educativo no sería posible ofrecer una respuesta válida y eficaz a las necesidades que presenta este colectivo. Tal com...

  11. Environmental and economic analysis of end of life management options for an HDPE product using a life cycle thinking approach.

    Science.gov (United States)

    Simões, Carla L; Pinto, Lígia M Costa; Bernardo, C A

    2014-05-01

    Manufacturers have been increasingly considering the implication of materials used in commercial products and the management of such products at the end of their useful lives (as waste or as post-consumer secondary materials). The present work describes the application of the life cycle thinking approach to a plastic product, specifically an anti-glare lamellae (used for road safety applications) made with high-density polyethylene (HDPE). This study shows that optimal environmental and economic outcomes associated with this product can be realized by recovering the material at the end of its useful life (end of life, EoL) and by using the recycled HDPE as a raw material in the production of new similar products. The study confirmed the applicability of the life cycle thinking approach by industry in sustainable products development, supporting the development of robust environmental and economic guidelines. PMID:24692456

  12. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ferreto, H. F. R., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Parra, D. F., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br; Lugão, A. B., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br [Center of Chemistry and Environment, Institute of Energy and Nuclear Research - IPEN (Brazil); Gaia, R., E-mail: renan-gaia7@hotmail.com [Faculdades Oswaldo Cruz (Brazil)

    2014-05-15

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  13. Optimization of high filler loading on tensile properties of recycled HDPE/PET blends filled with rice husk

    Science.gov (United States)

    Chen, Ruey Shan; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Salleh, Mohd Nazry

    2014-09-01

    Biocomposites of recycled high density polyethylene / recycled polyethylene terephthalate (rHDPE/rPET) blend incorporated with rice husk flour (RHF) were prepared using a corotating twin screw extruder. Maleic anhydride polyethylene (MAPE) was added as a coupling agent to improve the fibre-matrix interface adhesion. The effect of high filler loadings (50-90 wt%) on morphology and tensile properties of compatibilized rHDPE/rPET blend was investigated. The results of our study shown that composite with 70 wt% exhibited the highest tensile strength and Young's modulus, which are 22 MPa and 1752 MPa, respectively. The elongation at break decreased with increasing percentage of RHF. SEM micrograph confirmed fillers dispersion, morphological interaction and enhanced interfacial bonding between recycled polymer blends and rice husk. It can be concluded that the optimum RHF content is 70 wt% with maximum tensile strength.

  14. procesos de alta temperatura en pymes

    Directory of Open Access Journals (Sweden)

    ANDRÉS AMELL

    2007-01-01

    Full Text Available La búsqueda de tecnologías de calentamiento que reduzcan el consumo de combustible, disminuyan las emisiones contaminantes y mejoren la productividad de los procesos y calidad de los productos en procesos de alta temperatura, ha motivado la investigación y desarrollo tecnológico de sistemas térmicos. En este contexto el artículo presenta los resultados del proyecto “Desarrollo y Evaluación de un Sistema de Combustión Autoregenerativo y Radiante para Procesos de Alta Temperatura en Pequeñas y Medianas Empresas PyMES”, presentando la configuración, funcionamiento, caracterización, parámetros de operación y comportamiento de un prototipo desarrollado que opera con 28 kW de potencia térmica con base al poder calorífico inferior, factores de aireación de 1.05 y 1.20 y temperaturas de precalentamiento de aire hasta de 700ºC.

  15. Utilização de filmes de polietileno de baixa densidade(PEBD) para prolongar a vida pós-colheita de morangos, cv. oso grande The use of low density polyethylene packing to prolong the postharvest life of 'oso grande' strawberries

    OpenAIRE

    Joel Donazzolo; Maurício Hunsche; Auri Brackmann; Alessandro Jaquiel Waclawovsky

    2003-01-01

    Desenvolveu-se um experimento com o objetivo de avaliar o efeito da atmosfera modificada (AM), utilizando filmes de polietileno de baixa densidade (PEBD), sobre a manutenção da qualidade de morangos (Fragaria ananassa L.), cv. Oso Grande, acondicionados em câmara frigorífica, a 0ºC, e em câmara de climatização, a 20ºC, simulando transporte/armazenamento refrigerado e o transporte/armazenamento convencional, sob altas temperaturas respectivamente. Os morangos foram acondicionados em bandejas p...

  16. Dosimetric evaluation of multi-sided irradiation on HDPE pipes under 2 MeV electron beam

    International Nuclear Information System (INIS)

    The use of electron beam technology has enabled the production of heat resistant pipe for hot water circulation. One of the difficulties in the irradiation of pipe products is the uneven penetration of electrons. Quality of the radiation process depends on radiation dose and homogeneity of the dose distribution, which becomes a major concern when treatments of circular objects like pipes are performed. One method to achieve uniformity in the absorbed dose in the product is to use multi-sided irradiation. The paper discusses the importance of dosimetry mapping in industrial electron beam radiation processing and outlines the challenges in delivering a uniform dose to cylindrical objects. In this study, HDPE pipe of 5 mm thickness of homogeneous material (40 mm outer diameter and 30 mm inner diameter) has been chosen for multi-sided irradiation under 2 MeV scanned electron beam from the ILU-6 accelerator. - Highlights: • The paper outlines the challenges in delivering uniform dose to cylindrical objects at 2 MeV industrial electron beam facility. • HDPE pipe of 40 mm outer diameter and 30 mm inner diameter has been chosen for the study. • The circumferential dose distribution inside and outside of the pipes were evaluated by using calibrated CTA dosimeter strips. • Using stack of dosimeter strips, changes in circumferential dose distribution in the annular region of the pipe was evaluated. • Optimization of multi-sided irradiation on the HDPE pipes for better dose homogeneity is reported in the paper

  17. Research on the suitability of organosolv semi-chemical triticale fibers as reinforcement for recycled HDPE composites

    Directory of Open Access Journals (Sweden)

    Nour-Eddine El Mansouri

    2012-11-01

    Full Text Available The main objective of this research was to study the feasibility of incorporating organosolv semi-chemical triticale fibers as the reinforcing element in recycled high density polyethylene (HDPE. In the first step, triticale fibers were characterized in terms of chemical composition and compared with other biomass species (wheat, rye, softwood, and hardwood. Then, organosolv semi-chemical triticale fibers were prepared by the ethanolamine process. These fibers were characterized in terms of its yield, kappa number, fiber length/diameter ratio, fines, and viscosity; the obtained results were compared with those of eucalypt kraft pulp. In the second step, the prepared fibers were examined as a reinforcing element for recycled HDPE composites. Coupled and non-coupled HDPE composites were prepared and tested for tensile properties. Results showed that with the addition of the coupling agent maleated polyethylene (MAPE, the tensile properties of composites were significantly improved, as compared to non-coupled samples and the plain matrix. Furthermore, the influence of MAPE on the interfacial shear strength (IFSS was studied. The contributions of both fibers and matrix to the composite strength were also studied. This was possible by the use of a numerical iterative method based on the Bowyer-Bader and Kelly-Tyson equations.

  18. Dispersing hydrophilic nanoparticles in hydrophobic polymers: HDPE/ZnO nanocomposites by a novel template-based approach

    Directory of Open Access Journals (Sweden)

    G. Filippone

    2014-05-01

    Full Text Available The efficiency of a novel template-based approach for the dispersion of hydrophilic nanoparticles within hydrophobic polymer matrices is investigated. The procedure envisages the permeation of a well dispersed nanoparticle suspension inside a micro-porous matrix, obtained through selective extraction of a sacrificial phase from a finely interpenetrated co-continuous polymer blend. Specifically, a blend of high density polyethylene (HDPE and polyethylene oxide (PEO at 50/50 wt% is prepared by melt mixing. The addition of small amounts of organo-clay promotes the necessary refinement of the blend morphology. Once removed the PEO, the micro-porous HDPE matrix is dipped in a colloidal suspension of zinc oxide nanoparticles which exhibits low interfacial tension with HDPE. A system prepared by traditional melt mixing is used as reference. Melt- and solid-state viscoelastic measurements reveal a good quality of the filler dispersion despite the uneven distribution on micro-scale. The latter can be capitalized to minimize the filler content to attain a certain improvement of the material properties or to design nano-structured polymer composites.

  19. Photocatalytic degradation of methylene blue in water solution by multilayer TiO2 coating on HDPE

    International Nuclear Information System (INIS)

    A multilayer photocatalytic TiO2 coating on a high-density polyethylene (HDPE) disk was found to degrade aqueous methylene blue in a batch reactor study. The TiO2 coating was fabricated by a low-temperature method using polyurethane resin (PU) as a barrier layer for HDPE and as a binding agent for two TiO2 layers. Adequate adhesion between the HDPE substrate and PU barrier in aqueous environment was ensured with an oxygen plasma treatment. The photocatalytic effect of immersed TiO2 coating on the degradation of methylene blue in aqueous solution was monitored by UV-vis spectrometry as a function of UV-illumination time. Samples were allowed to adsorb methylene blue in the dark for 1 h before the UV-degradation experiments were started. The percentages of methylene blue degraded during 6 h UV illumination (λ = 365 nm) varied from 80% to 92%. The degradation followed pseudo-first order reaction kinetics, and the observed rate constants (kobs) were between 0.27 and 0.43 h-1.

  20. Transporte de juvenis de curimbatá Prochilodus lineatus em diferentes densidades =Transportation of curimbata Prochilodus lineatus juveniles in different densities

    Directory of Open Access Journals (Sweden)

    André Fernando Nascimento Gonçalves

    2010-04-01

    Full Text Available Neste estudo foi avaliado o efeito do transporte de curimbatá Prochilodus lineatus, em três densidades (100, 150 e 250 g L-1, sobre a sobrevivência e variáveis metabólicas, iônicas e hematológicas (série vermelha. Juvenis de curimbatá foram transportados em sacos plásticos durante 6h e amostrados antes da embalagem, imediatamente após a chegada, 24 e 96h após o transporte. Os peixes transportados na densidade mais alta apresentaram maior mortalidade durante o período de recuperação. As variáveis físico-químicas da água: condutividade e amônia total apresentaram maiores valores quanto maior a densidade (p This study evaluated the effects of curimbata Prochilodus lineatus transportation in three densities (100, 150 and 250 g L-1 on survival, metabolic, ionic and hematological (red series variables. Curimbata juveniles were transported in plastic bag during six hours, and sampled before packing, immediately after the arrival, 24 and 96 hours after transportation. During recovery, higher mortality was seen in fish transported in the highest density. Water variables, such as conductivity and total ammonia, presented increased values as density increased (p < 0.05, whereas the opposite occurred with dissolved oxygen. Glucose level observed in the arrival was high, significantly reducing after 96 hours. Among ionic variables, chloride decreased in higher fish densities and according to sampling times. Red series hematological variables, such as hematocrit, red blood cell and hemoglobin, increased in arrival, but diminished 96 hours after transportation. There were no significant differences in the interaction between density and time of sampling for mentioned variables. 250 g L-1 density induced the highest mortality rate and the worst variables values measured. 96 hours of recovery after the stressing event was enough to return to initial values for hematological variables, but was not sufficient to return to initial values for

  1. HDPE/纳米SiO2杂化材料的动态流变行为研究%The Study of the Dynamic Rheological Behavior of the HDPE/Nano-SiO2 Hybrid Materials

    Institute of Scientific and Technical Information of China (English)

    施海华; 周井隆; 龚方红; 熊煦; 刘春林; 陶国良

    2011-01-01

    Vinyl trimethoxysilane (VTMS) was grafted to the chain of the high density-polyethylene (HDPE) via melt grafting reaction. The tetraethoxysilane (TEOS) which acts as precursor was mixed with grafted HDPE,and then the HDPE/SiO2 hybrid materials were prepared by sol-gel process. The dynamic rheological behavior of the prepared high density-polyethylene/nano-silica hybrid composites was investigated by plate rheometer.Experimental results show that the complex viscosity (η*) of the composites increases with increasing the content of SiO2. When the SiO2 content of the hybrid composite reaches 1.2%, its complex viscosity η* increases suddenly and the shear thinning behavior appears. In the low frequency region, both the curves of the storage module G' vs. frequency ω and loss module G" vs. ω of the HDPE/SiO2 appear a second flat; and on the curve of the strain γ vs. storage module G', there appears two linear viscoelastic sections. These phenomena can be attributed to the links between the nano-SiO2 particles and polymer matrix in the hybrid system by chemical bonds and the uniform distribution of the nano-SiO2 particles; while when the nano-SiO2 content reaches 1.2%, the "solid-like" behavior may occur between the particles.%通过熔融接枝反应将乙烯基三甲氧基硅烷(VTMS)接枝到高密度聚乙烯(HDPE)分子链上,以四乙氧基硅烷(TEOS)为前驱体,加入接枝的HDPE中,通过溶胶-凝胶法(Sol-Gel)制备了HDPE/SiO2杂化材料,使用平板流变仪研究了纳米SiO2对HDPE/纳米SiO2杂化材料的动态流变行为的影响.结果表明,当SiO2含量达到1.2%时,复数黏度η*发生突变,并出现强烈的剪切变稀:低频区,储能模量G'、损耗模量G"出现第二平台;对应的应变y-G'曲线上,体系出现两段线性粘弹区域.这些现象表明由于杂化体系中纳米SiO2粒子与基体聚合物间通过化学键链接,并且均匀分布,在纳米粒子的含量达到1.2%时,粒子间就

  2. High density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) polymer blend studies related to recycling co-mingled plastics

    Science.gov (United States)

    Tsai, Pang-Yen

    Polymer blends of virgin high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) were studied as an attempt to relate the microstructure to the mechanical properties of the blends. The virgin blends were prepared by extrusion and then injection molded into specimens for characterization. Two of the virgin blends were tested for possible compatibilization using a styrene-ethylene-butylene-styrene (SEBS) block copolymer. In addition, six blends of post-consumer resins (PCRs) of HDPE and PET were included in this work for comparison. The moduli of the virgin blends showed positive deviation from those expected from the rule of mixtures. The synergism of the composite moduli can be explained partly by a Poisson's effect. Yield strengths of the blends molded at low injection chamber temperatures (200sp°, 230sp°, and 250sp°C) followed the rule of mixtures well, because PET filaments found in the composites had very high length to diameter ratios. When the injection chamber temperature was above the PET melting point (˜254sp°C), PET filaments were found to break down into particles, and the yield strengths of the blends coincided with the values expected from the inverse rule of mixtures. Impact strengths of the virgin blends were much less than that of a HDPE homopolymer due to poor interfacial bonding between HDPE and PET. Compatibilization appeared to be advantageous since it dramatically improved the impact strength of the virgin blends. SEM micrographs of impact fractured surfaces revealed that the improved adhesion from compatibilization and the presence of numerous uniaxially aligned PET filaments in the HDPE substrate can account for the significant increases in fracture resistance of the compatibilized blends. Mechanical performance of the PCRs was inferior to that of the virgin blends. Aside from polymer degradation and contamination due to repeated processing and handling, absence of PET filaments and interfacial bonding could be

  3. Calibration of Big Bottle RAD H2O set-up for radon in water using HDPE bottles

    International Nuclear Information System (INIS)

    Glass bottles are generally employed for water sampling because glass is impervious to radon and is not lost during sample storage. On the other hand, glass is fragile and may break, so 1 L High Density PolyEthylene (HDPE) bottles (Thermo Scientific Nalgene) are tested in place of glass vessels employing Big Bottle RAD H2O device (Durridge Company) coupled with RAD7 monitor. The purpose of this calibration is to quantify radon loss during storage in HDPE bottles, evaluate possible radon uptake by known volume of desiccant (Drierite, granular CaSO4) and quantify radon interaction with the rubber and plastic parts of the experimental circuit. These processes have been separately investigated, performing proper experiments for the assessment of their influence on resulting radon data using seven series of solutions at known activity concentrations in the range from 27 to 194 Bq/L. Percent radon loss during storage in 1 L HDPE bottles has been estimated at 0.0045 min−1. Radon absorption by desiccant, expressed as ‘equivalent’ volume of Drierite is 0.673 ± 0.092 L and is somehow independent, within errors, from i) the amount of water already absorbed in Drierite, ii) a recirculation time greater than 30 min and iii) radon concentrations. Radon absorption/desorption from rubber and plastic parts of the experimental device has been assessed as a function of concentration gradient between the inner volume of the circuit and the pores of polymer's. A final algorithm accounting for the above described physical processes has been developed for long runs (2–3 h). A simplified calculation method for short measurements (30 min) is also provided. - Highlights: • Big Bottle RAD H2O set-up for measuring radon in water was calibrated. • Glass bottles were replaced with HDPE vessels because too fragile for water sampling. • Radon diffusion coefficient through HDPE was calculated. • Radon absorption by Drierite and polymers in the setup was quantified.

  4. High efficiency motors; Motores de alta eficiencia

    Energy Technology Data Exchange (ETDEWEB)

    Uranga Favela, Ivan Jaime [Energia Controlada de Mexico, S. A. de C. V., Mexico, D. F. (Mexico)

    1992-12-31

    This paper is a technical-financial study of the high efficiency and super-premium motors. As it is widely known, more than 60% of the electrical energy generated in the country is used for the operation of motors, in industry as well as in commerce. Therefore the importance that the motors have in the efficient energy use. [Espanol] El presente trabajo es un estudio tecnico-financiero de los motores de alta eficiencia y los motores super premium. Como es ampliamente conocido, mas del 60% de la energia electrica generada en el pais, es utilizada para accionar motores, dentro de la industria y el comercio. De alli la importancia que los motores tienen en el uso eficiente de la energia.

  5. Effect of titanium dioxide (TiO{sub 2}) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shichao; Zhang, Jun, E-mail: zhangjun@njtech.edu.cn

    2014-12-25

    Highlights: • HDPE/TiO{sub 2} composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO{sub 2} composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO{sub 2}) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO{sub 2} particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO{sub 2} particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO{sub 2} particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO{sub 2} particles in HDPE matrix. It was found the rutile TiO{sub 2} could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result.

  6. Thermal characterization of the HDPE/LDPE blend (10/90) irradiated using gamma-rays

    Energy Technology Data Exchange (ETDEWEB)

    Puig, C.C., E-mail: cpuig@usb.v [Universidad Simon Bolivar, Departamento de Ciencia de los Materiales, Grupo de Polimeros USB, Apdo. 89000, Caracas 1080-A (Venezuela, Bolivarian Republic of); Albano, C., E-mail: calbano@ivic.v [Instituto Venezolano de Investigaciones Cientificas (IVIC), Centro de Quimica, Laboratorio de Polimeros, Apdo. 21827, Caracas 1020-A (Venezuela, Bolivarian Republic of); Universidad Central de Venezuela, Facultad de Ingenieria, Escuela de Ingenieria Quimica, Laboratorio de Polimeros, Caracas (Venezuela, Bolivarian Republic of); Laredo, E. [Universidad Simon Bolivar, Departamento de Fisica, Grupo de Fisica de Materiales Amorfos y Cristalinos, Apdo. 89000, Caracas 1080-A (Venezuela, Bolivarian Republic of); Quero, E. [Universidad Simon Bolivar, Departamento de Ciencia de los Materiales, Grupo de Polimeros USB, Apdo. 89000, Caracas 1080-A (Venezuela, Bolivarian Republic of); Karam, A. [Instituto Venezolano de Investigaciones Cientificas (IVIC), Centro de Quimica, Laboratorio de Polimeros, Apdo. 21827, Caracas 1020-A (Venezuela, Bolivarian Republic of)

    2010-05-01

    Gamma irradiation effect over the properties of slow cooled and fast cooled HDPE/LDPE 10/90 blend was studied. The blend and the neat polyethylenes were irradiated at room temperature in the presence of air using the following doses (4.8 kGy/h): 0, 50, 150, 400 and 1000 kGy. Differential scanning calorimetry (DSC) experiments were carried out using the following heating rates: 5, 10 and 20 deg. C/min. DSC results for the slow and fast cooled blend showed traces with three melting peaks and with increasing irradiation dose two melting peaks were obtained, i.e. the high melting peak shifts toward lower temperatures to merge with the intermediate melting peak into one endotherm. No changes in crystal structure by X-ray diffraction were found as a result of samples irradiation. Radiation crosslinking prevents crystal rearrangements during heating in the DSC. Gel content and melt flow index (MFI) measurements showed that radiation induced a high degree of crosslinking for all samples; gel content values were above 50% and a drop of more than 90% in the MFI was found. Irradiation of slow cooled samples resulted in larger values of gel content and lower MFI values than for fast cooled samples, mainly because of the higher degree of crosslinking for the former.

  7. Thermal characterization of the HDPE/LDPE blend (10/90) irradiated using γ-rays

    International Nuclear Information System (INIS)

    Gamma irradiation effect over the properties of slow cooled and fast cooled HDPE/LDPE 10/90 blend was studied. The blend and the neat polyethylenes were irradiated at room temperature in the presence of air using the following doses (4.8 kGy/h): 0, 50, 150, 400 and 1000 kGy. Differential scanning calorimetry (DSC) experiments were carried out using the following heating rates: 5, 10 and 20 deg. C/min. DSC results for the slow and fast cooled blend showed traces with three melting peaks and with increasing irradiation dose two melting peaks were obtained, i.e. the high melting peak shifts toward lower temperatures to merge with the intermediate melting peak into one endotherm. No changes in crystal structure by X-ray diffraction were found as a result of samples irradiation. Radiation crosslinking prevents crystal rearrangements during heating in the DSC. Gel content and melt flow index (MFI) measurements showed that radiation induced a high degree of crosslinking for all samples; gel content values were above 50% and a drop of more than 90% in the MFI was found. Irradiation of slow cooled samples resulted in larger values of gel content and lower MFI values than for fast cooled samples, mainly because of the higher degree of crosslinking for the former.

  8. Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP)

    International Nuclear Information System (INIS)

    The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution/reprecipitation method, as well as pyrolysis. In the first technique, different solvents/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail outlets). The recovery of polymer in every case was greater than 90%. FT-IR spectra and tensile mechanical properties of the samples before and after recycling were measured. Furthermore, catalytic pyrolysis was carried out in a laboratory fixed bed reactor with an FCC catalyst using again model polymers and waste products as raw materials. Analysis of the derived gases and oils showed that pyrolysis gave a mainly aliphatic composition consisting of a series of hydrocarbons (alkanes and alkenes), with a great potential to be recycled back into the petrochemical industry as a feedstock for the production of new plastics or refined fuels

  9. Optical properties of carbon materials filled HDPE composites in THz region

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiliang; MA Mingwang; YANG Xiaomin; YANG Kang; LIU Dan; JI Te; WU Shengwei; ZHU Zhiyong

    2009-01-01

    The optical and electrical properties of several composites,formed by filling the high density polyethylene (HDPE) with similar amount of carbon black (CB),multi-walled carbon nanotubes (MWNT) and fullerene (C60),respectively,were characterized using a THz-TDS setup.It was found that the optical parameters and the details of their variation with frequency differ significantly for different kinds of carbon materials.The results are analyzed by using Cole-Cole formula of dipole relaxation under the assumption that carbon particles dispersed in the matrix behave like dipoles and contribute mainly to the dielectric loss in the THz frequency range.Fitting results indicate that MWNT and CB filled composites have a broader distribution of the relaxation time compared with C60 which possesses a nearly single relaxation time.Compared with CB and C60,MWNT filled composite possesses the larger relaxation strength due to its higher electron density and larger conductive clusters.The real part of conductivity for three kinds of composites all follows power law behavior with respect to frequency but the exponents are quite different.These phenomena may be related to the special properties of the fillers as well as their particulate structures,such as aspect ratio,particle size,and aggregate structure,etc.

  10. Pyrolysis and Gasification of Solid, Organic, Low-Level Nuclear Waste: HDPE as a Case Study

    International Nuclear Information System (INIS)

    As environmental concerns have become a high priority matter, treatment of waste and especially radioactive waste are considered as a big global issue. The Israeli national radioactive waste disposal site is situated at the Nuclear Research Center Negev (NRCN). Radioactive waste from hospitals, research institutions and industry is delivered to the site. Pyrolysis is the thermochemical decomposition process of organic materials in the absence of oxygen to produce char, pyrolysis oil and gas. Gasification is defined as the thermal, non combustion, decomposition of organic material with a limited amount of oxygen and/or steam. Both processes are considered today as advanced thermal treatment technologies leading to mass and volume reduction of radioactive/hazardous organic waste, while retaining the radionuclides and inorganic material in solid form to be further disposed. In the present study, the thermal decomposition of High Density Poly-Ethylene (HDPE) was investigated combining two experimental systems. Thermo-Gravimetric Analysis (TGA) was used to measure the maximal decomposition rates at different pyrolytic experimental conditions and obtain the activation energy of the decomposition reaction. Product distribution and the extent of conversion to gas under pyrolytic and partial oxidating conditions (gasification) have been obtained from experiments performed in the pyrolysis/gasification system. Gas analysis was performed using Gas Chromatography (GC).

  11. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    International Nuclear Information System (INIS)

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials

  12. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    Energy Technology Data Exchange (ETDEWEB)

    Tazi, M.; Erchiqui, F. [Engineering department, Université de Quebec en Abitibi-Témiscamingue (Canada); Kaddami, H. [Université Caddi Ayad Marrakech, Laboratoire ’LCO2MC’, B.P. 549, Marrakech 40000, Maroc (Morocco); Bouazara, M. [Mechanical department, Université de Québec à Chicoutimi Canada (Canada); Poaty, B. [Technology Center of industrial residuals, QC Canada (Canada)

    2015-05-22

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials.

  13. Controlling Short-Range Interactions by Tuning Surface Chemistry in HDPE/Graphene Nanoribbon Nanocomposites.

    Science.gov (United States)

    Sadeghi, Soheil; Zehtab Yazdi, Alireza; Sundararaj, Uttandaraman

    2015-09-01

    Unique dispersion states of nanoparticles in polymeric matrices have the potential to create composites with enhanced mechanical, thermal, and electrical properties. The present work aims to determine the state of dispersion from the melt-state rheological behavior of nanocomposites based on carbon nanotube and graphene nanoribbon (GNR) nanomaterials. GNRs were synthesized from nitrogen-doped carbon nanotubes via a chemical route using potassium permanganate and some second acids. High-density polyethylene (HDPE)/GNR nanocomposite samples were then prepared through a solution mixing procedure. Different nanocomposite dispersion states were achieved using different GNR synthesis methods providing different surface chemistry, interparticle interactions, and internal compartments. Prolonged relaxation of flow induced molecular orientation was observed due to the presence of both carbon nanotubes and GNRs. Based on the results of this work, due to relatively weak interactions between the polymer and the nanofillers, it is expected that short-range interactions between nanofillers play the key role in the final dispersion state. PMID:26266528

  14. Estudio de la densidad mamográfica como modificador de riesgo de cáncer de mama en mujeres con mutación BRCA1/2

    OpenAIRE

    Tamayo Orjuela, Luisa Fernanda

    2015-01-01

    El cáncer de mama es el tumor más frecuente en la mujer y uno de los problemas de salud más importante por los índices de mortalidad y morbilidad asociados. Los factores de riesgo más frecuentes para desarrollar esta enfermedad son la historia familiar y la edad de la mujer. En un 5-10% de la población con cáncer de mama se detecta un tumor hereditario debido a una mutación heredada de los padres. Actualmente, la alta densidad mamográfica medida en las mamografías, se considera un factor ...

  15. World Wide Web Search Engines: AltaVista and Yahoo.

    Science.gov (United States)

    Machovec, George S., Ed.

    1996-01-01

    Examines the history, structure, and search capabilities of Internet search tools AltaVista and Yahoo. AltaVista provides relevance-ranked feedback on full-text searches. Yahoo indexes Web "citations" only but does organize information hierarchically into predefined categories. Yahoo has recently become a publicly held company and currently…

  16. Crecimiento de Colossoma macropomum en estanques de tierra en dependencia de la densidad.

    OpenAIRE

    Jorge Günther; Jorge Boza; Nazira Gálvez

    2016-01-01

    Se analiza el crecimiento y la utilización de alimento del tambaquí, Colossoma macropomum, cultivado a densidades de 0,5, 1 y 2 peces/m2 en estanques de tierra de 60m2 con alimento balanceado con 35% proteína. No se encontraron diferencias estadísticas significativas con respecto a la densidad. Sin embargo, el crecimiento obtenido fue mucho menor que en otro ensayo realizado en las mismas condiciones y simultáneamente en un estanque de 3000 m2, por lo que se discute la hipótesis de que el cre...

  17. Fitomassa de adubos verdes e controle de plantas daninhas em diferentes densidades populacionias de leguminosas.

    OpenAIRE

    Fernandes, Marcelo Ferreira; Barreto, Antônio Carlos; Emídio Filho, João

    1999-01-01

    O objetivo deste trabalho foi avaliar a fitomassa de calopogônio, mucuna-preta, mucunarajada,feijão-de-porco, guandu de porte alto, Crotalaria spectabilis e C. breviflora sob diferentes densidades de semeadura (10, 20, 40, 80 e 160 sementes viáveis m-2), e o crescimento de plantas daninhas nessas densidades, em área de tabuleiros costeiros. O experimento foi desenvolvido de maio a agosto de 1996, no Campo Experimental “Antônio Martins”(EMDAGRO/Embrapa-CPATC), em Lagarto, SE. O número de plant...

  18. Turismo em territórios de grande densidade religiosa

    Directory of Open Access Journals (Sweden)

    Siegrid Guillaumon

    2012-12-01

    Full Text Available Resumo ----- O turismo tem sido entendido por organismos internacionais como atividade com grande potencial para promover o desenvolvimento econômico e, ao mesmo tempo, que valoriza a cultura e promove a preservação das paisagens naturais. Seguindo as diretrizes internacionais, no Brasil, o turismo passou a ser entendido como uma indústria com grande potencial para gerar empregos e divisas, e se fortalece por meio da promoção da diversidade cultural, que pode estar associada às diversas culturas materiais e religiosas. Para compreender a gestão do turismo em contextos que articulam cultura, religião e desenvolvimento territorial, este ensaio teórico aponta limitações nos dois conceitos disponíveis na literatura, quais sejam, o conceito de turismo cultural e o conceito de turismo religioso, ao mesmo tempo que propõe o conceito de ‘turismo em territórios de grande densidade religiosa’, o qual incorpora o reconhecimento das dinâmicas de poder presentes nos territórios como elementos que interferem na forma como se planeja o turismo. Mobilizam-se entendimentos do campo da antropologia e da geografi a para a gestão a fim de sustentar que a discussão teórica conduzida tem um potencial explicativo para o turismo em diversas escalas territoriais, e, também, em contextos nos quais existe o diálogo entre turismo e religião. ----- Tourism in Territories of High Religious Density ----- Abstract ----- Tourism has been understood by international organizations as an activity with great potential to promote economic development, while valuing cultures and promoting the protection of natural landscapes. Following international guidelines, tourism in Brazil has begun to be understood as an industry with great potential to generate jobs and income and is strengthened through the promotion of cultural diversity which may be associated with material and religious cultures. To understand the management of tourism in contexts that

  19. Densidades de carga utilizadas para el transporte de bovinos destinados a matadero en Chile Stocking densities used to transport cattle to slaughter in Chile

    Directory of Open Access Journals (Sweden)

    C Gallo

    2005-01-01

    Full Text Available Se determinaron las densidades de carga empleadas en el transporte de 413 cargas (camionadas de bovinos, que comprendieron un total de 12.931 animales, recibidos en dos plantas faenadoras en Chile durante el año 2002, una en la X Región y la otra en la Región Metropolitana. Para las cargas recibidas en la planta de la X Región, las densidades de carga registradas fluctuaron entre 106 y 693 kg/m² (promedio 457 ± 6,6 kg/m² y en la Región Metropolitana fluctuaron entre 268 y 632 kg/m² (promedio 453 ± 9,7 kg/m². En ambas regiones se observó una tendencia a que las densidades de carga usadas en los vehículos de mayor tamaño (camiones simples y con carro fueran mayores; la mayoría de las cargas animales eran transportadas en este tipo de vehículo. Las densidades de carga encontradas para los viajes más largos no difirieron de aquellas usadas para los viajes cortos en el caso de la Región Metropolitana; sin embargo, en el caso de las cargas recibidas en la X Región se observó que en general los animales transportados por distancias más largas viajaron a densidades de carga mayores. En general, 32,4% de las 413 cargas revisadas, que correspondieron a 35,6% de todos los bovinos, sobrepasaron el límite de densidad de carga permitido por la legislación vigente (500 kg/m². Considerando que la literatura indica que el ganado bovino transportado a muy altas densidades, particularmente sobre 500 kg/m², sufre mayor estrés y produce inferior calidad de carne, especialmente en términos de mayor incidencia de contusiones, y que, además, en Chile las canales con contusiones que afectan el tejido muscular sufren una degradación en cuanto a la categoría de tipificación, reduciendo su valor económico, se recomienda, tanto desde el punto de vista de bienestar animal como de calidad de carne, al menos respetar el límite máximo de densidad de carga establecido para el transporte de ganado bovino en ChileThe stocking densities employed in

  20. Evaporation of carbon using electrons of a high density plasma; Evaporacion de carbono usando los electrones de un plasma de alta densidad

    Energy Technology Data Exchange (ETDEWEB)

    Muhl, S.; Camps, E.; Escobar A, L.; Garcia E, J.L.; Olea, O. [Instituto de Investigaciones en Materiales, UNAM, C.P. 04510 Mexico D.F. (Mexico)

    2000-07-01

    The high density plasmas are used frequently in the preparation of thin films or surface modification, for example to nitridation. In these processes, are used mainly the ions and the neutrals which compose the plasma. However, the electrons present in the plasma are not used, except in the case of chemical reactions induced by collisions, although the electron bombardment usually get hot the work piece. Through the adequate polarization of a conductor material, it is possible to extract electrons from a high density plasma at low pressure, that could be gotten the evaporation of this material. As result of the interaction between the plasma and the electron flux with the vapor produced, this last will be ionized. In this work, it is reported the use of this novelty arrangement to prepare carbon thin films using a high density argon plasma and a high purity graphite bar as material to evaporate. It has been used substrates outside plasma and immersed in the plasma. Also it has been reported the plasma characteristics (temperature and electron density, energy and ions flux), parameters of the deposit process (deposit rate and ion/neutral rate) as well as the properties of the films obtained (IR absorption spectra and UV/Vis, elemental analysis, hardness and refractive index). (Author)

  1. EFEITO DAS ALTAS DENSIDADES DE ESTOCAGEM NO CRESCIMENTO E SOBREVIVÊNCIA DE Litopenaeus vannamei NA FASE FINAL DE ENGORDA, CULTIVADOS EM SISTEMAS DE BIOFLOCOS (BFT

    Directory of Open Access Journals (Sweden)

    Adriana Ferreira Silva

    2013-09-01

    Full Text Available The aim of this study was to evaluate the effect of high stocking densities on survival, growth and feed conversion rates of Litopenaeus vannamei shrimp, in final growout phase, in a Biofloc Technology (BFT culture system, keeping the same water parameters for all treatments. Shrimps (11.96 ± 1.14 g were stocked in microcosms (0.50/m2 tanks, connected to a BFT system raceway. The study was carried out for 45 days. The shrimp were stocked at densities of 150, 300, 450 and 600 shrimp/m2. Bioflocs were collected for analysis of proximate composition. The results were submitted to one-way ANOVA, and differences were compared by Tukey test (α = 0.05. In T300 and T450, growth and survival were not affected by high stocking densities. The highest biomass reached (T450 was 5.1kg/m² and the best feed conversion rate was 1.54 in T150. The results of this study indicate that stocking densities in the proposed system can be high, but not exceeding 450 shrimp/m². Furthermore, even maintaining the same water parameters for all treatments, there was a negative effect between density and shrimp growth, confirming that this effect is behavioral.

  2. Efecto del ejercicio en subpoblaciones de lipoproteínas de alta densidad y en la presión arterial

    OpenAIRE

    Nieto Cárdenas, Olga Alicia; García Cardona, Diana María; Jiménez, Jorge Alberto; Landázuri, Patricia

    2013-01-01

    Objetivo Determinar la relación del ejercicio con los niveles séricos de la apoA-I y las subpoblaciones de HDL2 y HDL3, en personas hipertensas de la Ciudad de Armenia - Quindío.Métodos La intervención fueron dos meses de ejercicio. La presión arterial se tomó con las recomendaciones del Ministerio de Salud de Colombia. Las subpoblaciones de HDL se midieron con el método del precipitado ionico y la apoA-I se midió con la técnica de nefelometría de bindig site.Resultados Los datos se analizaro...

  3. Operador de densidad y operadores producto en resonancia magnética nuclear

    OpenAIRE

    Paniagua, Juan Carlos

    2015-01-01

    Breve introducción al formalismo del operador de densidad y su aplicación a la resonancia magnética nuclear. Incluye el método de los operadores producto para analizar la evolución de sistemas de espines.

  4. Grafting of Glycidylmethacrylate onto HD-PE by reactive injection moulding

    International Nuclear Information System (INIS)

    In this work, the free radical grafting of Glycidylmethacrylate (GMA) onto HD-PE, initiated by Di-tert-butyl-peroxide and Di(tert -butylperoxy)-2,5-dimethylhex-3-ine, was studied. Experiments were carried out in solution with 1,2-Dichlorobenzene as solvent and by reactive injection moulding. Monomer- and initiator-concentrations were varied and the influence of these parameters on the grafting yields and the content of residual monomer and homopolymer of GMA were studied. Additionally the mechanical and thermal properties of the grafting products were determined. Grafting yields were analyzed by FT-IR-spectroscopy, the residual monomer content by TGA, and the mechanical and thermal properties by means of tensile tests, TGA, and DSC. It was found, that the compositions of the grafted products were subject to change in a wide range depending on the initial concentrations of monomer and initiator. Grafting yields could be raised by increasing the initial content of peroxide as well as of monomer, the addition of high monomer concentrations lead to a decrease of the grafting yields. The amount of homopolymer and monomer residuals was varied by varying the monomer- and initiator-concentrations, too. Consequently the Youngs-Modulus, crystallinity, and the melting and degradation behaviour varied as well as function of the composition, whereby the content of monomer residuals showed the highest impact on the mechanical properties, while the crystallinity was subject to change as a function of the grafting yield. This was most probably due to variations in length and the distribution of the grafted chains, which was shown through IR-spectroscopy. The results indicated a significant impact on the mechanical and thermal properties by the formation of crosslinks between the PE-chains and β-cleavage reactions. (author)

  5. Influence of processing variables on the mechanical behavior of HDPE/clay nanocomposites

    Directory of Open Access Journals (Sweden)

    Renata Barbosa

    2012-06-01

    Full Text Available Nanocomposites were processed using the technique of melt intercalation, starting from a concentrated polar compatibilizer/organoclay (PE-g-MA/organoclay prepared in an internal mixer. The concentrate was incorporated into the matrix of HDPE by two methods: I counter-rotating twin-screw extruder and II co-rotating twin-screw extruder, using two screw profiles (ROS and 2KB90. After extrusion, the specimens of the extruded composites were injection molded. The X-ray diffraction (XRD technique was used to analyze the degree of expansion of the prepared clays. To analyze the degree of exfoliation of obtained nanocomposites, XRD and TEM (transmission electron microscopy were used. The influence of processing variables on mechanical properties was studied through the behavior of the modulus and tensile strength of nanocomposite systems. By XRD and TEM, it was seen that the clay was well dispersed in the matrix and the presence of intercalated and partially exfoliated hybrid structure for nanocomposites was observed when the systems were prepared in counter-rotating twin-screw extruder. A similar behavior was observed in the use of screws (2KB90 or ROS of the nanocomposites, with a reduction in modulus and tensile strength. Although the mixing process by extruding be the most common industrial practice, and also it is the preferred strategy for the preparation of polymer nanocomposites, much of the literature was directed to the study of chemical modification of clay, type and level of compatibilizer, in order to maximize the compatibility between clay and the polymeric matrix. On the other hand, studies about the role of the processing and configurations of screws are relatively scarce. The main motivation of this work was to expand and to contribute to spread a better understanding of the effects of processing to obtain polymer nanocomposites.

  6. Technical Letter Report - Preliminary Assessment of NDE Methods on Inspection of HDPE Butt Fusion Piping Joints for Lack of Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Susan L.; Cumblidge, Stephen E.; Doctor, Steven R.; Hall, Thomas E.; Anderson, Michael T.

    2008-05-29

    The U.S. Nuclear Regulatory Commission (NRC) has a multi-year program at the Pacific Northwest National Laboratory (PNNL) to provide engineering studies and assessments of issues related to the use of nondestructive evaluation (NDE) methods for the reliable inspection of nuclear power plant components. As part of this program, there is a subtask 2D that was set up to address an assessment of issues related to the NDE of high density polyethylene (HDPE) butt fusion joints. This work is being driven by the nuclear industry wanting to employ HDPE materials in nuclear power plant systems. This being a new material for use in nuclear applications, there are a number of issues related to its use and potential problems that may evolve. The industry is pursuing ASME Code Case N-755 entitled “Use of Polyethylene (PE) Plastic Pipe for Section III, Division 1, Construction and Section XI Repair/Replacement Activities” that contains the requirements for nuclear power plant applications of HDPE. This Code Case requires that inspections be performed after the fusion joint is made by visually examining the bead that is formed and conducting a pressure test of the joint. These tests are only effective in general if gross through-wall flaws exist in the fusion joint. The NRC wants to know whether a volumetric inspection can be conducted on the fusion joint that will reliably detect lack-of-fusion conditions that may be produced during joint fusing. The NRC has requested that the work that PNNL is conducting be provided to assist them in resolving this inspection issue of whether effective volumetric NDE can be conducted to detect lack of fusion (LOF) in the butt HDPE joints. PNNL had 24 HDPE pipe specimens manufactured of 3408 material to contain LOF conditions that could be used to assess the effectiveness of NDE in detecting the LOF. Basic ultrasonic material properties were measured and used to guide the use of phased arrays and time-of-flight diffraction (TOFD) work that

  7. Efeito da densidade de estocagem no desenvolvimento inicial do acará-bandeira (Pterophyllum scalare

    Directory of Open Access Journals (Sweden)

    L.P. Gonçalves Júnior

    2013-08-01

    Full Text Available Avaliou-se a influência da densidade de estocagem no desenvolvimento inicial do acará-bandeira (Pterophyllum scalare. O desempenho produtivo foi avaliado pelo ganho de peso (GP, ganho de comprimento total (GCT, ganho de comprimento padrão (GCP, ganho de altura (GA, taxa de crescimento específico (TCE, taxa de desenvolvimento específico (TDE e sobrevivência (S. Para realização do experimento, foram utilizadas 300 pós-larvas de peso médio inicial de 0,0012g, comprimento total médio de 4,11±0,93mm, altura média inicial de 4,84±0,87mm e comprimento padrão médio de 1,54±0,25mm. Essas foram distribuídas em delineamento inteiramente ao acaso, em cinco tratamentos com quatro repetições. Os tratamentos (T foram constituídos por cinco diferentes densidades de estocagem, em que T1: 5 pós-larvas L-1; T2: 10 pós-larvas L-1; T3: 15 pós-larvas L-1; T4: 20 pós-larvas L-1; T5: 25 pós-larvas L-1. A densidade de 5 pós-larvas L-1 foi a que proporcionou o maior valor para crescimento. Contudo, essa densidade subestimou a utilização do espaço se comparada com a produtividade final da densidade de 15 pós-larvas L-1.

  8. SURFACE MODIFICATION OF SUGARCANE BAGASSE CELLULOSE AND ITS EFFECT ON MECHANICAL AND WATER ABSORPTION PROPERTIES OF SUGARCANE BAGASSE CELLULOSE/ HDPE COMPOSITES

    Directory of Open Access Journals (Sweden)

    Daniella Regina Mulinari

    2010-05-01

    Full Text Available Cellulose fibres from sugarcane bagasse were bleached and modified by zirconium oxychloride in order to improve the mechanical properties of composites with high density polyethylene (HDPE. The mechanical properties of the composites prepared from chemically modified cellulose fibres were found to increase compared to those of bleached fibres. Tensile strengths of the composites showed a decreasing trend with increasing filler content. However, the values for the chemically modified cellulose fibres/HDPE composites at all mixing ratios were found to be higher than that of neat HDPE. Results of water immersion tests showed that the water absorption affected the mechanical properties. The fracture surfaces of the composites were recorded using scanning electron microscopy (SEM. The SEM micrographs revealed that interfacial bonding between the modified filler and the matrix was significantly improved by the fibre modification.

  9. Research on electromagnetic interference shielding effectiveness of sisal fiber/carbon black/HDPE composites by tri-screw extrusion molding

    Science.gov (United States)

    Zhou, Li-Ying; Wu, Ming-Chun; Huang, Zhao-Xia; He, He-Zhi

    2016-03-01

    Polymer composites filled with fillers such as carbon black(CB) can become an electrical conductor, which is gaining popularity for electromagnetic shielding applications. In this paper, the method of tri-screw compounding was adopted to prepare SF/CB/HDPE composites, and the influence of different content of CB and SF on the properties such as shielding effectiveness(SE) and conductivity were studied. It was found that the composites with higher content of CB showed higher electromagnetic SE. Added 8% SF to CB/HDPE system, the performance of composites was significantly improved. Finally, values of theoretical and experimental SE of SF/CB/HDPE composites were compared and the results were in good correlation, which proved out the significance of theoretical guidance of Schelkunoff formula.

  10. Comportamento de cultivares de cafeeiro em diferentes densidades de plantio The behavior of coffee cultivars under different plant densities

    Directory of Open Access Journals (Sweden)

    Edison Martins Paulo

    2005-01-01

    Full Text Available Avaliou-se em Adamantina, na Região da Alta Paulista, em São Paulo, entre maio de 1995 e junho de 2000, o crescimento e quatro produções de cafeeiros das cultivares de porte baixo Catuaí Amarelo IAC 47 e Obatã IAC 1669-20 de Coffea arabica L., submetidas às densidades de plantio de 2.500, 5.000, 7.519 e 10.000 plantas ha-1, com uma planta por cova. Estudou-se também a população de 2.500 plantas.ha-1 em covas com duas plantas com 2,0 m de distância na linha de plantio. Adotou-se o delineamento estatístico de blocos ao acaso com três repetições, com parcelas subdivididas, onde as parcelas foram as populações e as subparcelas, as cultivares. Os resultados permitiram inferir que, no período estudado, o aumento da densidade influenciou positivamente a altura e negativamente o diâmetro do caule e da base da copa dos cafeeiros, mas não a altura da inserção do primeiro ramo plagiotrópico a partir do nível do solo. O aumento da população de cafeeiros acarretou menor produção de café beneficiado por planta, mas concorreu para o aumento da produtividade no período de 1997 a 2000. O plantio de duas mudas de café por cova acarretou também diminuição do diâmetro do caule e da produção individual dos cafeeiros. Observou-se na cultivar Catuaí Amarelo IAC 47 maior diâmetro da base da copa e maior crescimento em altura, enquanto a cv. Obatã IAC 1669-20 evidenciou seu maior diâmetro do caule. As cultivares Catuaí Amarelo IAC 47 e Obatã IAC 1669-20 não diferiram entre si quanto à produção individual e à produtividade de café beneficiado no quadriênio (1997-2000.This experiment was developed at Adamantina, west region of the State of São Paulo, Brazil, during May of 1995 to June of 2000. The plant growth and productivity of two coffee cultivars Catuaí Amarelo IAC 47 and Obatã IAC 1669-20, were evaluated considering to plant densities of 2.500, 5.000, 7.519 and 10.000 plants ha-1. The density of 2500 also was

  11. Effect of Photostablizers on Surface Color and Mechanical Property of Wood-flour/HDPE Composites after Weathering

    Institute of Scientific and Technical Information of China (English)

    XUE Ping; JIA Mingyin; WANG Kejian; DING Yun; WANG Linna

    2012-01-01

    The effects of photostabilizers of ultraviolet absorbers (UVA),hindered amine light stabilizer (HALS) and pigment on surface color change and mechanical properties of weathered wood-flour/polyethylene (HDPE) composites were investigated.After being added UVA with high UV absorbance,the WPC exhibites better ability to resist color fading and mechanical property loss.High molecular weight HALS is found to be the most effective in controlling long term fading and yellowing changes.Pigments cover the composites for remaining the original color after weathering regardless of less contribution to mechanical property.Addition of photostabilizer and pigment together show great synergism in decreasing color fading and flexural property loss.

  12. Determination of thermal and mechanical properties of HDPE-based polymer blends for use in traffic signs

    Directory of Open Access Journals (Sweden)

    Andrea San-Gil-León

    2016-06-01

    Full Text Available Two recycled high-density polyethylene specimens and two recycled high-density polyethylene blends were characterized in terms of their thermal and mechanical properties with the purpose of assessing their suitability for the construction of traffic signs. Traffic signs constructed from recycled plastics provide an application for materials that otherwise with end up in landfills. The HDPE composite containing 25% LDPE and 5% ABS had the best mechanical and thermal performance. Of importance is the recycling of ABS that traditionally had not been recycled locally and found its final fate in landfills.

  13. MEASUREMENT AND MODELLING OF SORPTION EQUILIBRIUM CURVE OF WATER ON PA6, PP, HDPE AND PVC BY USING FLORY-HUGGINS MODEL

    OpenAIRE

    Suherman Suherman; Mirko Peglow; Evangelos Tsotsas

    2012-01-01

    The sorption of water on granular polyamide-6 (PA6), granular polypropylene (PP), and powdery high density polyethylene (HDPE) and powdery polyvinyl chloride (PVC) were measured using a gravimetric method in a magnetic suspension balance (MSB). The Flory-Huggins model was successfully applied on the sorption equilibrium curve of all investigated polymers. The influence of temperature is low. The value of Flory-Huggins parameters(c) of PA6, PVC, PP and HDPE were 1.8, 5.8, 6.3, and 8.1, respect...

  14. Alta Capital venitab Kruudale tasumisega / Sten-Aleks Pihlak

    Index Scriptorium Estoniae

    Pihlak, Sten-Aleks

    2008-01-01

    Alta Capital Partnersid pole veel maksnud Oliver Kruudale 2007. aasta septembris müüdud Tere ja Kalevi eest. Vt. samas: Rahasaamise venimine on lükanud Kalevi viimastel kuudel laenurallile. Kommenteerib Aivar Häelm

  15. A densidade básica e característica anatômicas variam radialmente na madeira de Astronium graveolens Jacq. (Anacardiaceae. Basic density and anatomical features vary in the radial direction in the wood of Astronium graveolens Jacq. (Anacardiaceae.

    Directory of Open Access Journals (Sweden)

    Camila Moura SANTOS

    2011-12-01

    Full Text Available Estudos sobre variações nas dimensões celulares de espécies arbóreas de clima tropical são escassos. Sendo assim, o objetivo deste trabalho foi caracterizar a variação da densidade básica e da anatomia no sentido radial da madeira de Astronium graveolens Jacq. Coletaram-se cinco indivíduos da espécie, provenientes da Estação Experimental Luiz Antônio (SP. Os métodos empregados nas análises foram os usualmente utilizados em pesquisas de densidade e anatomia de madeira. De acordo com os resultados foram constatadas altas correlações entre densidade básica, comprimento de fibra, espessura da parede da fibra, diâmetro de vaso e frequência de vaso com a distância da medula. A densidade básica da madeira é altamente dependente do comprimento das fibras, espessura da parede das fibras e diâmetro dos vasos, ocorrendo aumento no sentido da medula para a casca.Studies on variations in cell sizes of tree species in tropical climate are scarce. Thus, the aim was characterize the radial variation of basic density and wood anatomy of Astronium graveolens Jacq. Five specimens were collected at the Luiz Antônio Experimental Station,(SP. Sstandard methods for studying the density and wood anatomy were employed. According to the results we observed high correlation among basic density,fiber length, fiber wall thickness, vessel diameter and vessel frequency with distance fromthe pith. The wood density is highly dependent on fiber length, fiber wall thicknessand vessel diameter, there was an increase towards the pith to bark.

  16. Degradação de poliolefinas utilizando catalisadores zeolíticos Degradation of polyolefins using zeolitic catalysts

    OpenAIRE

    Maria Letícia M. Valle; Maria José O. C. Guimarães; Cristiane M. S. Sampaio

    2004-01-01

    Neste trabalho foi estudada a degradação de alguns dos principais constituintes dos rejeitos plásticos (polietileno de alta densidade (HDPE), polietileno de baixa densidade (LDPE) e polipropileno (PP)), empregando-se um catalisador exausto de unidades de craqueamento de fluidos (FCC) e um catalisador zeolítico (ADZ3) sintetizado em laboratório. Utilizando técnicas de termogravimetria (TG-DTG) e cromatografia gasosa (CG), foi possível avaliar os produtos gerados no craqueamento destas poliolef...

  17. Substitution potentials of recycled HDPE and wood particles from post-consumer packaging waste in Wood-Plastic Composites.

    Science.gov (United States)

    Sommerhuber, Philipp F; Welling, Johannes; Krause, Andreas

    2015-12-01

    The market share of Wood-Plastic Composites (WPC) is small but expected to grow sharply in Europe. This raises some concerns about suitable wood particles needed in the wood-based panels industry in Europe. Concerns are stimulated by the competition between the promotion of wooden products through the European Bioeconomy Strategy and wood as an energy carrier through the Renewable Energy Directive. Cascade use of resources and valorisation of waste are potential strategies to overcome resource scarcity. Under experimental design conditions, WPC made from post-consumer recycled wood and plastic (HDPE) were compared to WPC made from virgin resources. Wood content in the polymer matrix was raised in two steps from 0% to 30% and 60%. Mechanical and physical properties and colour differences were characterized. The feasibility of using cascaded resources for WPC is discussed. Results indicate the technical and economic feasibility of using recycled HDPE from packaging waste for WPC. Based on technical properties, 30% recycled wood content for WPC is feasible, but economic and political barriers of efficient cascading of biomass need to be overcome. PMID:26376122

  18. Sugarcane bagasse ash reinforced HDPE composites: effects of electron-beam radiation crosslinking on tensile and morphological properties

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Jaciele G.; Gomes, Michelle G.; Oliveira, Rene R.; Silva, Valquiria A.; Sartori, Mariana M.; Ortiz, Angel V.; Moura, Esperidiana A.B., E-mail: jacielegteixeira@yahoo.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Environmental issues have led to the development of polymeric materials reinforced with fibers originated from renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Although sugarcane bagasse fiber residues has been extensively studied and used as a source of reinforcement of polymers, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries and as a result of its burning, tons of ashes are produced. Due to the inorganic composition, ashes can be used as reinforcement in polymeric materials. This study presents the preparation and characterization of a composite based on HDPE matrix and sugarcane bagasse ashes as reinforcement cross-linked by electron-beam radiation. The HDPE /Ash composite (95:5 wt %) was obtained by using a twin-screw extruder machine followed by injection molding. After extrusion and injection molding process, the composites were subjected to electron-beam radiation, at radiation doses of 150 kGy and 250 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The irradiated and non-irradiated composite specimens were characterization by tensile and MFI tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and sol-gel analysis. In addition, ash from bagasse fiber was characterized by WDXRF. (author)

  19. Crecimiento de Colossoma macropomum en estanques de tierra en dependencia de la densidad.

    Directory of Open Access Journals (Sweden)

    Jorge Günther

    2016-03-01

    Full Text Available Se analiza el crecimiento y la utilización de alimento del tambaquí, Colossoma macropomum, cultivado a densidades de 0,5, 1 y 2 peces/m2 en estanques de tierra de 60m2 con alimento balanceado con 35% proteína. No se encontraron diferencias estadísticas significativas con respecto a la densidad. Sin embargo, el crecimiento obtenido fue mucho menor que en otro ensayo realizado en las mismas condiciones y simultáneamente en un estanque de 3000 m2, por lo que se discute la hipótesis de que el crecimiento del tambaquí esté relacionado con el tamaño del estanque.

  20. Preparation and characterizations of HDPE-EVA alloy/OMT nanocomposites/paraffin compounds as a shape stabilized phase change thermal energy storage material

    International Nuclear Information System (INIS)

    A kind of shape stabilized phase change nanocomposites materials (PCNM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA) alloy, organophilic montmorillonite (OMT), paraffin and intumescent flame retardant (IFR) are prepared using twin-screw extruder technique. The structures of the HDPE-EVA alloy/OMT nanocomposites are evidenced by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that an ordered intercalated nanomorphology of the HDPE-EVA alloy/OMT nanocomposites is formed. Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy (SEM). The HDPE-EVA alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure. The paraffin acts as a phase change material and disperses in the three-dimensional network structure. Its latent heat is given by differential scanning calorimeter (DSC) method. The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM, respectively. The thermal stability properties are characterized by thermogravimetric analysis (TGA). The TGA analysis results indicate that the flame retardant shape stabilized PCNM produce a larger amount of char residue at 800 deg. C than that of shape stabilized PCNM, although the onset of weight loss of the flame retardant shape stabilized PCNM occur at a lower temperature. The formed multicellular char residue contributes to the improvement of thermal stability performance. The probable combustion mechanisms are also discussed in this paper

  1. Comportamento de poedeiras criadas a diferentes densidades e tamanhos de grupo em ambiente enriquecido

    Directory of Open Access Journals (Sweden)

    Danilo Florentino Pereira

    2013-06-01

    Full Text Available O objetivo deste trabalho foi determinar diferenças comportamentais entre poedeiras criadas sob diferentes densidades e tamanhos de grupo, em condições de ambiente enriquecido. Foram utilizadas poedeiras Isa Brown com idade entre 30 e 32 semanas alojadas em galpões de escala reduzida e distorcida. As aves foram criadas durante 28 dias, em baias com cama de maravalha, poleiro e ninho. Foram avaliados dois tamanhos de grupos (6 e 12 aves e duas densidades de criação (774 e 1.440 cm² por ave, em arranjo fatorial com três repetições. Em amostras de vídeo de 15 min, foram registrados as frequências e os tempos de expressão dos comportamentos: arrumar penas, banho de areia, bater asas, beber água, bicar, coçar a cabeça, ciscar, comer, empoleirar, esticar perna, perseguir, sentar e visitar o ninho. Foram observados efeitos significativos dos tratamentos e da interação entre eles. O grupo de seis aves manifestou aumento da frequência de comportamentos que indicam maior frustração das aves, independentemente da densidade. O tamanho de grupo é o fator mais importante para o bem-estar das aves.

  2. Carriles para alta velocidad. Comportamiento en fatiga

    Directory of Open Access Journals (Sweden)

    Duart, J. M.

    2005-02-01

    -aire inducido. Los ensayos de fatiga de los carriles soldados se llevan a cabo por flexión en cuatro puntos en concordancia con la norma europea. El método Locati, descrito en esta nota, está basado en la Ley de Miner de daño acumulado y en las curvas de Wohler del material ensayado. Permite calcular, con precisión suficiente, las tensiones límites de fatiga al 50%. Así, los valores obtenidos, en ensayos a dos millones de ciclos, para carriles sin soldar (Sf = 353 MPa, carriles soldados con precalentamiento de oxipropano (Sf = 225 MPa y carriles soldados con precalentamiento de propano-aire inducido (Sf = 210 MPa son muy similares y aceptables a los estipulados por los métodos de determinación del límite de fatiga según norma europea. Debido a la comodidad, rapidez y bajo coste del método Locati resulta, en nuestra opinión, muy adecuado para el control de calidad de los procesos de soldadura aluminotérmica en vigor, de carriles de alta resistencia.

  3. 聚乙烯管韧性破坏寿命预测方法研究%Prediction of Ductile Rupture Failure Life of HDPE Pipe

    Institute of Scientific and Technical Information of China (English)

    徐成; 徐平; 施建峰; 郭伟灿

    2012-01-01

    There are three typical failure modes of high density polyethylene (HDPE) pipe under hydrostatic pressure, which are ductile rupture caused by creep, slow crack growth and degradation. The duration time of HDPE pipe under hydrostatic pressure before ductile rupture failure is predicted based on a visco - elastic model. It is found that hoop stress increases due to reduction in wall thickness of HDPE pipe, while yielding stress decreases owing to decrease of strain rate. When the hoop stress approaches the instant yielding stress, HDPE pipe quickly deforms and then structural failure will follow. The relationship between hydrostatic pressure and failure life of HDPE pipe are obtained.%聚乙烯管在静液压作用下有3种失效模式:蠕变韧性破坏、慢速裂纹脆性破坏和材料劣化破坏.提出基于粘弹性应力分析模型的聚乙烯管材蠕变韧性破坏寿命预测方法.在内压作用下,聚乙烯管材的蠕变导致其壁厚不断减薄,环向应力逐渐增大.同时,基于粘弹性应力分析模型得到管材蠕变的应变率逐渐减小,由于聚乙烯的屈服应力具有明显的率相关性,屈服应力也随之逐渐减小.当增加后的环向应力值与管材瞬时屈服应力相等时,聚乙烯管材发生韧性失效,从而得到韧性失效寿命与内压载荷之间的关系.

  4. Metodologia para estudo do volume e densidade absoluta da placenta humana de termo

    Directory of Open Access Journals (Sweden)

    Del Nero Ulisses

    2002-01-01

    Full Text Available OBJETIVO: comparar duas metodologias para o cálculo do volume placentário em gestações normais de termo: a do princípio de Arquimedes e a do volume do cilindro, para estimar a densidade absoluta da placenta. Definir a metodologia mais adequada para o cálculo do volume e densidade placentários, que se relacione com o peso e classificação do recém-nascido. MÉTODOS: foram estudadas 50 placentas provenientes de gestações de termo sem complicações e calculados o volume e a densidade absoluta placentários: a pelo princípio de Arquimedes e b na suposição de que a placenta seria uma secção de cilindro com duas alturas diferentes do bolo placentário: com a altura média e com a altura da média aritmética do centro e extremidades. As densidades absolutas placentárias foram calculadas pelo quociente entre o peso ao ar da placenta e os diferentes volumes. RESULTADOS: a maioria das gestantes eram multíparas, idade média de 25,4 anos, volume placentário médio entre 547,8 e 610 cmsuperscript three e densidade média entre 0,94 e 1,14 g/cmsuperscript three, dependendo da metodologia empregada. CONCLUSÕES: a metodologia mais adequada para estimar o volume placentário no termo foi a do princípio de Arquimedes, pela melhor correlação com o peso dos recém-nascidos, o índice placentário e a classificação do peso dos recém-nascidos em relação à idade gestacional.

  5. Rendimiento de plantas de tomate injertadas y efecto de la densidad de tallos en el sistema hidropónico Yield of tomato crop as a result of grafting and shoot density in hydroponic system

    Directory of Open Access Journals (Sweden)

    Roberta M.N. Peil

    2004-06-01

    Full Text Available El cultivo de tomate en primavera con baja densidad inicial de plantas y luego aumentar-se la densidad efectiva mediante el desarrollo de tallos laterales, cuando las integrales diarias de radiación son altas, parece ser una manera prometedora de incrementar el número de frutos m-2 y uniformizar el tamaño del fruto; y presenta la ventaja adicional de requerir-se un menor número de plantas para la superficie de cultivo. Por lo tanto, se ha llevado a cabo un ensayo cuyo objetivo ha sido evaluar los efectos de la densidad de tallos sobre el rendimiento y la uniformidad de los frutos de un cultivo de tomate injertado y no injertado. El cultivo se realizó de marzo a julio de 1998, en las condiciones de invernadero en Almería (sudeste español. La densidad inicial de plantación fue de 2,4 y 3,0 plantas m-2, en el caso de las plantas no injertadas, que presentaban un único tallo en el transplante; y 1,2 plantas m-2 en las plantas injertadas, que tenían dos tallos (2,4 tallos m-2. A partir del mes de abril, mediante el desarrollo de tallos laterales (cuando el tratamiento así lo exigía se pasó a tener las siguientes densidades: 2,4; 3,0 y 3,5 tallos m-2 (plantas injertadas y no injertadas; y 3,0 plantas no injertadas m-2 a un tallo durante todo el ciclo. Los resultados muestran que plantas de tomate injertadas y transplantadas a dos tallos tuvieron igual producción total, pero frutos de tamaño más uniforme, que plantas no injertadas transplantadas a un tallo y con doble densidad de plantas. Dentro del rango de 2,4 a 3,5 tallos m-2, una mayor densidad de tallos aumentó la producción precoz y dio un tamaño más uniforme de frutos, no afectando su peso promedio y la producción total. La adición de tallos laterales (3,0 tallos m-2 supuso una reducción de un 20% en el rendimiento total, pero vino acompañada por un ahorro de un 21% y de un 39% en el número de plantas no injertadas e injertadas, respectivamente, necesarias para la misma

  6. Densidade microvascular no carcinoma de língua Microvascular density in carcinoma of the tongue

    Directory of Open Access Journals (Sweden)

    ALI AMAR

    2002-09-01

    Full Text Available OBJETIVO: Avaliar a densidade microvascular no carcinoma epidermóide de língua oral, no sítio primário e em suas metástases linfáticas. MÉTODOS: Foram avaliados retrospectivamente 30 pacientes com carcinoma epidermóide restrito à língua oral, submetidos a tratamento cirúrgico incluindo esvaziamento cervical. A densidade microvascular foi avaliada por imunohistoquímica empregando o anticorpo anti-CD34 e quantificada à microscopia óptica, no tumor primário e em suas metástases linfonodais. Foi avaliada a relação entre a densidade microvascular, as variáveis clínicas e histológicas e o prognóstico. RESULTADOS: A densidade microvascular apresentou mediana de 15,4 vasos/campo (5,5 a 25,3 nos tumores primários e 16,4 vasos/campo (12 a 32,2 nas metástases linfáticas. Foi observada uma relação inversa entre a densidade microvascular no tumor primário e na respectiva metástase linfática (r= -0,68 e p=0,04. A densidade microvascular não apresentou relação com outras variáveis histológicas ou com o prognóstico. CONCLUSÃO: Há Uma relação inversa entre a densidade microvascular no sítio primário e na metástase linfonodal, sugerindo um controle regional ou sistêmico da angiogênese.BACKGROUND. Assessment of microvascular density in squamous cell carcinoma of the oral tongue (primary lesion and metastasis. METHODS. Immunohistochemical analysis by anti CD-34 of neoangiogenesis density and its relation with clinical and histological data concerning the prognosis. After optic microscopy amplification, the relation between microvascular density, clinico-histological data and prognosis, was established. RESULTS. The microvascular density presented 15.4 vessels/field (5.5 to 25.3 in primary tumors and 16.4 vessels/field (12 to 32.2 in lymph node metastases. It was observed an inverse relation between microvascular density in primary lesions and their lymph node metastasis (r= -0.68 and p=0,04. CONCLUSIONS. No evidence was

  7. Modeling of the cooling rate effect on the residual stress formation in the cantala fiber/recycled HDPE composites

    Science.gov (United States)

    Probotinanto, Yosafat C.; Raharjo, Wijang W.; Budiana, Eko P.

    2016-03-01

    Residual stress has great influence on the mechanical properties of polymer composites. Therefore, its formation during the manufacturing process needs to be investigated. The aim of this study is to investigate the influences of cooling rate on the residual stress distribution of the cantala/rHDPE composite by simulation. The simulation was done by using a SOLID227 element type of ANSYS. The cooling rates that used in this study are 0.5°C/minute, 1°C/minute, and 60°C/minute. The values of the residual stress correspond to the increasing of the cooling rate are 1171.31 kPa, 1171.42 kPa, 1172.36 kPa. In the radial direction, the residual stress was tensile inside the fibers, while in the longitudinal direction, the tensile residual stress occurred in the matrix zones and compressive in the fiber zones.

  8. The influence of dose rate and oxygen on the irradiation induced degradation in high density polyethylene (HDPE)

    International Nuclear Information System (INIS)

    High density polyethylenes (HDPE), used in orthopedic implants was irradiated using γ rays at room temperature (250C) in air and in N 2 for different dose and dose rate, and it was then stored in the same environment for 3 days at 250C. Electronic paramagnetic resonance (EPR) measurements showed decay as well as changes from radicals in air due to reaction with oxygen. In presence of N 2 on the other hand, free radicals decayed without any observable transformation from one type to another. Concerning FTIR and DSC measurements, it was found that the oxidative degradation takes place during irradiation and the oxidation products increase with decreasing dose rate. The expressiveness of these processes depends on the dose and on the presence of oxygen. Also, the fusion and crosslinking temperatures where established along with the increase of irradiation dose. In contrary the area related to the DSC spectrum was found to increase with increasing dose

  9. Parâmetros sangüíneos de pacu Piaractus mesopotamicus (Holmberg, 1887 alimentados com dietas suplementadas com cromo trivalente em duas densidades de estocagem = Hematological parameters of pacu Piaractus mesopotamicus (Holmberg, 1887 fed diets supplemented with trivalent chromium in two stocking densities

    Directory of Open Access Journals (Sweden)

    Rodrigo Yudi Fujimoto

    2007-10-01

    Full Text Available O objetivo deste trabalho foi avaliar os efeitos da suplementação com cromo trivalente (0, 6, 12 e 18 mg kg-1 de ração sobre as variáveis hematológicas de Piaractus mesopotamicus, mantidos em duas densidades de estocagem (4 e 20 kg m-3. Os mantidos na maior densidade e alimentados com dietas suplementadas com 0 e 6 mg de cromo kg-1apresentaram redução do número de linfócitos circulantes, sugerindo má adaptação a essa condição de alta densidade. Nas dietas suplementadas com 12 e 18 mg kg-1, tal efeito não foi observado, porém verificou-se aumento do número de trombócitos no tratamento com 12 mg de cromo kg-1. A inexistência de diferença significativa entre os tratamentos, aos 30 dias, sugere a adaptação dos peixes ao tipo de alimento e à situação de alta densidade. Portanto, nas condições deste ensaio, a suplementação com 12 e 18 mg de cromo kg-1 é interessante como estratégia alimentar durante 15 dias.This work evaluated the effects of chromium supplementation on thehematological parameters of Piaractus mesopotamicus Holmberg, 1887 maintained in two stocking densities. Fish were fed diets supplemented with 0, 6, 12 and 18 mg trivalent chromium kg-1 dry ration and maintained at 4 and 20 kg m-3. The fish under high stockingdensity and fed diets supplemented with 0 and 6 mg kg-1 showed reduction in the number lymphocytes, which suggests non-adaptation to this condition of high density. This was not observed in fish fed diets supplemented with 12 and 18 mg chromium kg-1, but an increasein the number of thrombocytes was evident. The lack of difference between treatments after 30 days may suggest a possible adaptation of fish to the situation. It can be added that supplementation with 12 and 18 mg chromium kg-1 is an interesting feeding strategy for aperiod of 15 days.

  10. Efeito da adição de diferentes copolímeros em blendas HDPE/HIPS pós-consumo: morfologia de fases e propriedades térmicas The effect of different block copolymers on post consumer HDPE/HIPS Blends: phase morphology and thermal properties

    Directory of Open Access Journals (Sweden)

    Igor S. B. Perez

    2008-09-01

    Full Text Available Blendas de poliolefinas/HIPS têm sido exploradas para obter filmes especiais com determinadas propriedades desejadas, tornando imperativo desenvolver vários estudos para um melhor conhecimento do comportamento desses materiais. Neste trabalho, efeitos da adição dos copolímeros comerciais de estireno-butadieno multibloco (SBS e de estireno-(etileno-co-butileno-estireno (SEBS tribloco linear em blendas pós-consumo de HDPE e HIPS são reportados. A diminuição nas dimensões da microfase dispersa, aliada à rugosidade superficial da fase HDPE após extração seletiva do HIPS, independentemente de a fase matriz ser HIPS ou HDPE, mostraram mais eficiência do SEBS como modificador interfacial de tensão ou como surfactante entre os diferentes domínios quando comparado com o SBS. Os resultados das caracterizações térmicas, por exemplo, menor Tm e menor grau de cristalinidade do HDPE, e maior Tg do poliestireno na presença de SEBS corroboraram esta conclusão, como será discutido posteriormente.Blending of post-consumer polyolefins/HIPS has been exploited for obtaining special films with a desired set of properties, which has required studies to understand the behavior of these materials. In this work the effects of commercial multiblock styrene-butadiene (SBS and linear triblock styrene-(ethylene-co-butylene-styrene (SEBS copolymers in blends of post-consumer high density polyethylene (HDPE and HIPS are reported. Thermal properties and phase morphology were comparatively analyzed for the additives aiming at verifying possible correlations between them. Decreased dimensions of the minor micro phase along with HDPE surface roughness after HIPS selective extraction, independently of the matrix being HIPS or HDPE, showed better effectiveness for SEBS as interfacial tension modifier or as surfactant at the different domains interface when compared with SBS. The results of thermal characterizations, e.g. lower HDPE melting temperature, lower

  11. High intensity Discharge lighting; Alumbrado de alta intensidad de descarga

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza E, Ernesto J. [Manufacturera de Reactores, S. A., Mexico, D. F. (Mexico)

    1993-12-31

    This paper gets into contact with some fundamentals in the operation of high discharge intensity lamps. There are useful definitions, as well as the study of the operation of high pressure sodium lamps and of metallic additives operating at less than nominal power. [Espanol] Este trabajo pone al lector en contacto con algunos fundamentos de la operacion de las lamparas de alta intensidad de descarga (HID). Se encuentra con definiciones utiles, asi como el estudio de la operacion de las lamparas de sodio en alta presion y de aditivos metalicos operando a una potencia menor que la nominal.

  12. Enriquecimiento curricular para el alumnado con altas capacidades en primaria

    OpenAIRE

    Boldú Caballero, Tomás

    2013-01-01

    La finalidad de este documento es proporcionar al lector, primero, una rápida ojeada a la trayectoria histórica de la atención a las NEE (más concretamente de las altas capacidades); segundo, una conceptualización de las altas capacidades y sus necesidades educativas específicas tomando como punto de referencia algunos de lo más eminentes autores y corrientes psicopedagógicas actuales o del pasado reciente; y por último, facilitar ejemplos prácticos desde la perspectiva del doc...

  13. Cócs. Hallmark of the Terra Alta

    OpenAIRE

    Maria Del Loreto Meix

    2004-01-01

    This article looks at the traditional cake making in the Terra Alta (Catalonien) area linked to festivities, and in particular the pastries usually made. In this area the pastries are known as cócs, a word common to Terra Alta and the neighbouring districts of Ribera d'Ebre and the Priorat. Locally produced mistelle, sweet or rancid wine is served with the pastries. Nowadays, the bakeries and cake makers in the area's towns and villages also produce traditionally crafted products, tha...

  14. A tomografia computadorizada de alta resolução na avaliação da toxicidade pulmonar por amiodarona High-resolution computed tomography of amiodarone pulmonary toxicity

    Directory of Open Access Journals (Sweden)

    Daniela Peixoto Consídera

    2006-04-01

    Full Text Available OBJETIVO: Avaliar as principais alterações identificadas na tomografia computadorizada de alta resolução do tórax em pacientes com toxicidade pulmonar pela amiodarona. MATERIAIS E MÉTODOS: Foram avaliadas dez tomografias computadorizadas de alta resolução de tórax de pacientes com pneumonite pela amiodarona, seis desses pacientes do sexo masculino e quatro do sexo feminino, com idade média de 73,5 anos. RESULTADOS: Os achados tomográficos mais relevantes foram opacidades lineares ou reticulares em seis casos (60%, pequenos nódulos com densidade elevada em seis casos (60%, consolidações densas em três casos (30% e aumento da densidade do parênquima hepático em cinco de oito casos em que havia estudo tomográfico do abdome superior (62,5%. CONCLUSÃO: A tomografia computadorizada de alta resolução é um exame importante na avaliação de pacientes com toxicidade pulmonar pela amiodarona, devendo ser realizada sempre que houver suspeita deste diagnóstico. O achado de espessamento de septos interlobulares associado a lesões com aumento de densidade é altamente sugestivo deste diagnóstico.OBJECTIVE: To evaluate the main findings of chest high-resolution computed tomography in patients with amiodarone pulmonary toxicity. MATERIALS AND METHODS: Ten patients - six male and four female, average age of 73.5 years - with amiodarone-induced pneumonitis have undergone chest high-resolution computed tomography. RESULTS: The most relevant tomographic findings were linear or reticular opacities in six cases (60%, small high density nodules in six cases (60%, dense consolidations in three cases (30% and increased density in the hepatic parenchyma in five of eight cases in which there was a superior abdomen CT scan (62.5%. CONCLUSION: The high-resolution computed tomography is a valuable non-invasive test for evaluating patients with amiodarone pulmonary toxicity and should always be performed when one suspects of the presence of this

  15. Competition in a rice - cowpea intercrop as affected by nitrogen fertilizer and plant population Competição em uma cultura consorciada de arroz-guandu em função do fertilizante nitrogenado e da densidade populacional de plantas

    Directory of Open Access Journals (Sweden)

    Frank Oke Oroka

    2007-12-01

    Full Text Available The increased productivity or yield advantage provided by intercropping is attributed to a better use of resources by crops grown in mixtures, as compared to the same species grown in sole stands. In an intercropping system with upland rice and cowpea, the intra and inter-competition was quantified, as affected by plant population density and rate of nitrogen. Reductions in number of panicles per rice plant and number of grains per panicle were obtained with high density in both sole and mixture rice populations. Increasing nitrogen rate did not affect yield and yield components in both populations, but number and weight of pods per plant of cowpea in sole stands increased. Land equivalent ratios exceeding unity were obtained, indicating an improved resource use by the crop mixture. Relative crowding coefficient and aggressivity indices showed cowpea to be the dominant crop, with rice being dominated. Nitrogen utilization efficiency was high with intercrops, but was generally poor in stands of high population density.O aumento em produtividade devido a plantios consorciados é atribuído ao melhor uso dos recursos presentes pelas plantas em desenvolvimento conjunto, em comparação às mesmas espécies crescendo em dosséis separados. Em um sistema consorciado de arroz e guandu quantificou-se as inter- e intra competições em relação à densidade populacional e taxa de aplicação de nitrogênio. Reduções significativas do número de panículas por planta de arroz e número de grãos por panícula foram observados para alta densidade, tanto para culturas solteira de arroz como em populações mistas. O aumento das doses de nitrogênio não afetou a produção e os componentes de produção em ambos os sistemas, ao passo que o número e peso de vagens por planta do guandu aumentaram em culturas solteiras. Foram obtidas razões de área equivalente maiores que a unidade, mostrando melhoria no uso da terra nas culturas mistas. O coeficiente

  16. Densidade de plantio, crescimento, produtividade e qualidade das frutas de morangueiro "Camino Real" em hidroponia

    Directory of Open Access Journals (Sweden)

    Isabelita Pereira Portela

    2012-09-01

    Full Text Available Com o objetivo de determinar o efeito da densidade de plantio sobre o crescimento da planta, a produtividade e características químicas relacionadas à qualidade organoléptica das frutas da cultivar de morangueiro Camino Real em sistema hidropônico do tipo NFT, diferentes densidades de plantio foram avaliadas: 15,0; 12,5; 10,7 e 9,3 plantas m-2, correspondentes ao espaçamento entre plantas de 0,25; 0,30; 0,35 e 0,40 m, sendo fixado o espaçamento entre linhas de 0,18 m. O sistema NFT foi constituído por bancadas de telhas de fibrocimento de 1,10 x 2,44 m, considerando-se cada ondulação côncava da telha como um canal de cultivo. O transplante foi realizado em 26-04-2010, encerrando-se o experimento em 05-01-2011. Avaliaram-se a matéria fresca e seca de folhas, coroa, raízes e frutas, a área foliar, o número de frutas e o peso médio das frutas. Amostras das frutas foram analisadas em relação ao teor de sólidos solúveis totais (SST e à acidez total titulável (ATT. Com base nos resultados obtidos, conclui-se que o crescimento e a produtividade individual das plantas da cultivar de morangueiro Camino Real não são afetados pela elevação da densidade de plantio, no intervalo entre 9,3 e 15,0 plantas m-2. O crescimento e a produtividade por unidade de área, bem como a concentração de sólidos solúveis totais e a relação SST/ATT apresentam resposta linear ao incremento da densidade de plantio. Sugere-se a adoção da densidade de 12,5 plantas m-2, que proporcionaria rendimento mais elevado (2,79 kg m-2 de frutas com adequadas características organolépticas e redução no número de mudas necessárias, em relação à densidade de 15,0 plantas m-2. Existe a necessidade de desenvolver estudos adicionais com a cultivar Camino Real, a fim de promover adaptações no sistema e verificar a viabilidade econômica de seu cultivo em hidroponia.

  17. Características del alumnado con altas capcidades

    OpenAIRE

    Grau Rubio, Claudia

    2012-01-01

    Se describen las características del alumnado con altas capacidades, la terminología más usual y la clasificación. Asimismo, se expone la teoría de la disincronía y los mitos relacionados con este alumnado.

  18. El niño, oscilación del sur (ENOS, con relación a la transmisión de malaria, densidad y paridad de An. albimanus y An. darlingi (diptera: culicidae en dos regiones de Colombia

    Directory of Open Access Journals (Sweden)

    Ricardo Mantilla

    2000-02-01

    Full Text Available

    Una fuerte asociación ha sido registrada entre los incrementos en la transmisiónas forzadas por el fenómeno El Niño. Entre las posibles explicaciones para esta asociación está el efecto del clima sobre la dinámica de población de vectores, por ejemplo, generando cambios en la densidad y en las tasas de sobrevivencia de la población, y en la cantidad y calidad de sitios de reproducción, como también a través de cambios en el período de incubación extrínseco del parásito dentro del vector. Con el propósito de evaluar la influencia de ENOS sobre la densidad y paridad de Anopheles albimanus y An. darlingi, y su relación con la transmisión de malaria, se realizó un estudio longitudinal en Chocó y Casanare. En cada área se seleccionaron dos localidades y se realizaron muestreos entomológicos durante una semana cada mes, desde finales de 1997 hasta 1999. Este período cubrió los eventos El Niño 1997 -1998 y La Niña 1998 - 2000. En las localidades de Chocó se observó un importante incremento en el número de casos de malaria durante el evento ENOS, asociado con la temperatura. No se observó una asociación estadísticamente significativa entre los casos de malaria y la precipitación o la humedad relativa. La relación entre el incremento de malaria durante El Niño y las variables entomológicas no fue evidente. La densidad y paridad de ambas especies de vectores fluctuaron durante el período de estudio y no se encontró una asociación significativa entre estas variables y los factores climáticos como la temperatura. La precipitación y la humedad relativa. La densidad de larvas de An. albimanus fluctuó durante el estudio, y mostró altas densidades alrededor de julio - agosto. No se observó asociación entre la densidad de larvas con la densidad de adultos o las variables climáticas. El efecto del evento ENOS sobre las poblaciones de vectores

  19. Variabilidade espacial da densidade e da porosidade de um Latossolo Vermelho Eutroférrico sob semeadura direta por vinte anos Spatial variability of soil bulk density and soil porosity on Rhodic Eutrudox under no tillage for twenty years

    Directory of Open Access Journals (Sweden)

    Glécio Machado Siqueira

    2009-09-01

    Full Text Available Todas as práticas de manejo causam impacto sobre os atributos do solo que se traduzem em influência sobre o desenvolvimento das culturas. Sabe-se que no sistema de semeadura direta ocorre compactação do solo na camada superficial, com tendência a progredir com o tempo de cultivo. Este trabalho teve como objetivo avaliar a variabilidade espacial da densidade e da porosidade de um Latossolo Vermelho eutroférrico sob semeadura direta por vinte anos. O trabalho foi desenvolvido em Campinas (SP considerando o período entre 1985 e 2005. Os atributos analisados neste estudo foram: argila (g kg-1, silte (g kg-1, areia (g kg-1, densidade (kg dm-3, porosidade total (%, macroporosidade (% e microporosidade (%. Ferramentas de geoestatística foram utilizadas para análise dos dados e construção de mapas de variabilidade espacial da densidade e da porosidade do solo. A amostragem realizada em 1985 não foi capaz de detectar a variabilidade espacial da densidade e porosidade do solo. Nos atributos físicos amostrados em 2005, observou-se alta razão de dependência espacial. Nos mapas de variabilidade espacial não se constatou relação clara entre a textura, a densidade e a porosidade do solo. Na área após vinte anos de manejo com semeadura direta não havia problemas com compactação. O manejo do solo com semeadura direta influenciou favoravelmente a variabilidade espacial dos atributos amostrados em 2005.Soil management practices affect its attributes which will further affect crop development. It is generally known and accepted that soil surface compaction occurs in no tillage system and that this compaction tends to increase with time. However, most of the research do not evaluate adequately soil physical properties behavior as affected by time of management. The objective of this work was to evaluate spatial variability of soil bulk density and soil porosity on a Rhodic Eutrudox under no tillage with annual crops for twenty years. The work

  20. Densidades de plantio na produtividade e qualidade de frutos de melancia

    OpenAIRE

    Anamaria RP Ramos; Rita de Cássia de S. Dias; Carlos Alberto Aragão

    2009-01-01

    O experimento foi conduzido na Embrapa Semi-Árido em Petrolina-PE, de setembro a dezembro de 2007, para avaliar o desempenho agronômico e a qualidade dos frutos de melancia cultivadas sob diferentes densidades de plantio. Foram avaliados três espaçamentos combinados com seis cultivares de melancia, sendo duas diplóides de polpa amarela (BRS Soleil e BRS Kuarah), duas triplóides (Híbrido Triplóide CPATSA e Extasy Seedless) e duas cultivares comerciais, também diploídes e de fruto pequeno (Smil...

  1. Chorros laminares de gas con valores muy dispares de las densidades del chorro y del ambiente

    OpenAIRE

    Sánchez Sanz, Mario

    2007-01-01

    En esta tesis se analiza la estructura de chorros laminares cuya densidad es muy diferente a la del ambiente en el que descargan debido a que, bien su temperatura o bien su peso molecular, son muy distintos. El estudio se centra en valores del número de Reynolds Re moderadamente grandes en los que el chorro continua siendo esbelto y estable. En este régimen, los términos correspondientes a la difusión axial y las variaciones transversales de presión pueden despreciarse en prime...

  2. Resultados da conjuntivodacriocistorrinostomia com implante de prótese lacrimal de polietileno de baixa densidade

    OpenAIRE

    Bison Simone; Soccol Ovídio; Scarpi Marinho Jorge

    2002-01-01

    Objetivos: Estabelecer quais são as complicações pós-operatórias da conjuntivodacriocistorrinostomia (CDCR) com implante de prótese lacrimal de polietileno de baixa densidade e relacionar a etiologia da obstrução e o aparecimento destas complicações e, conseqüentemente, o sucesso pós-operatório. Métodos: Foram analisadas 35 vias lacrimais submetidas a conjuntivodacriocistorrinostomia com implante de prótese lacrimal de polietileno. Com a finalidade de estudar as possíveis relações entre as va...

  3. Efeito da densidade de estocagem no desenvolvimento inicial do acará-bandeira (Pterophyllum scalare)

    OpenAIRE

    L.P. Gonçalves Júnior; S L Pereira; M.D. Matielo; P.P. Mendonça

    2013-01-01

    Avaliou-se a influência da densidade de estocagem no desenvolvimento inicial do acará-bandeira (Pterophyllum scalare). O desempenho produtivo foi avaliado pelo ganho de peso (GP), ganho de comprimento total (GCT), ganho de comprimento padrão (GCP), ganho de altura (GA), taxa de crescimento específico (TCE), taxa de desenvolvimento específico (TDE) e sobrevivência (S). Para realização do experimento, foram utilizadas 300 pós-larvas de peso médio inicial de 0,0012g, comprimento total médio de 4...

  4. Densidade e diversidade fenotípica de bactérias diazotróficas não simbióticas em solos da Reserva Biológica Serra dos Toledos, Itajubá (MG

    Directory of Open Access Journals (Sweden)

    Talita Filomena Silva

    2011-04-01

    Full Text Available Bactérias diazotróficas não simbióticas (BDNS atuam no desenvolvimento das plantas por meio da fixação biológica de nitrogênio e também pela produção e liberação de substâncias reguladoras do crescimento vegetal. Este estudo objetivou avaliar a densidade e diversidade fenotípica desse grupo de bactérias em fragmentos de solo da Reserva Biológica Serra dos Toledos e entorno, em Itajubá/MG. Essa reserva localiza-se na Área de Proteção Ambiental da Mantiqueira, constituindo-se em uma importante área de recarga e de abrigo à flora e fauna endêmicas. Amostras de solo superficial foram coletadas em áreas com diferentes declividades na reserva, em épocas representativas das estações de inverno (setembro/2006 e verão (abril/2007. A densidade, avaliada pelo número mais provável, utilizando os meios de cultura NFb, JNFb e Fam, para Azospirillum spp., Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0,12 a 75,60 (NMP x 10(5 bactérias g-1 solo seco. Foram obtidos 172 e 174 isolados, respectivamente para as amostras de inverno e verão, dos quais 30 e 55 % apresentaram similaridade igual ou superior a 70 % com as estirpes-tipo Azospirillum brasilense, A. amazonense, A. lipoferum, Herbaspirillum seropedicae e Burkholderia brasilensis. O resultado do comportamento dos isolados com base na tolerância à salinidade nem sempre foi semelhante ao obtido pelas características fenotípicas culturais a 70 % de similaridade, sendo indicado para estudos complementares de diversidade desses organismos. As BDNS apresentam potencial de utilização em estudos de avaliação da qualidade e sustentabilidade de ecossistemas. No entanto, apesar da alta densidade e diversidade fenotípica em solos da reserva, maiores valores foram obtidos no entorno, evidenciando o efeito positivo da cobertura vegetal do tipo gramíneas sobre elas, independentemente da variação climática.

  5. Investigación en materiales sometidos a altas presiones

    Directory of Open Access Journals (Sweden)

    Juan Carlos Fallas

    2010-10-01

    Full Text Available El estudio de materiales sometidos a altas presiones es un tema de profundo interés en el campo científico e ingenieril actual. Diferentes análisis experimentales permiten descubrir los efectos que esta condición genera en la estructura molecular de un determinado compuesto.La implementación de la celda de diamante para altas presiones ha revolucionado este tema en las últimas décadas, al ser una herramienta vital en el desarrollo de estas pruebas. Presiones superiores, inclusive a los 20 Gpa, pueden ser generadas con este artefacto.Adicionalmente, la posibilidad de caracterizar muestras bajo estos parámetros y la inclusión de otras variables, como altas temperaturas, ofrecen un ambiente propicio para la evaluación de materiales bajo condiciones extremas.Este artículo explica los fundamentos básicos de la ciencia de materiales a altas presiones. Aspectos relevantes acerca de la celda de diamante y de la ejecución de experimentos son tratados en diferentes apartados. Se quiere compartir los alcances que esta disciplina posee, así como diferentes resultados que se han logrado en varias aplicaciones.Investigaciones en materiales para el almacenamiento de hidrógeno y energía, así como la simulación de condiciones presentes a muy altas profundidades en la Tierra, son casos que se tomaron en cuenta para ejemplificar áreas donde existen aplicaciones sustanciales.

  6. Study of properties and the preparation of composite of wheat straw and HDPE/PP%麦秸粉与HDPE/PP基复合材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    杨兆哲; 许民

    2014-01-01

    本文采用麦秸粉为增强体,分别与高密度聚乙烯(HDPE)、聚丙烯(PP)热塑性塑料基体采用挤出方式混合制备木塑复合材料,研究麦秸粉与HDPE、PP的配比对复合材料性能的影响。利用高速混合机在一定条件下对麦秸粉、热塑性塑料和其他助剂进行混合,利用双螺杆挤出机熔融造粒,单螺杆挤出机挤出成型,对制备的麦秸粉/塑料复合材料进行物理力学性能测试。结果表明:加入少量麦秸粉使木塑复合材料力学性能降低,随着麦秸粉含量的增加,复合材料的力学性能呈提高的趋势;当麦秸粉含量超过一定比例时,木塑复合材料力学性能降低,且冲击性能降低明显;本次试验HDPE基木塑复合材料力学强度略高于PP基木塑复合材料。%The paper is mixing the raw materials of wheat straw as enhanceosome and high-density polyethylene/pohyprpylene (HDPE/PP) of thermoplastic to produced wood-plastic com-posite by adopting extrusion way and researching effect about the content of HDPE and PP on the properties of composite. Under a certain conditions,the high-speed mixer mixed the com-pound of wheat straw powder and thermoplastics and other auxiliaries,and then the compound were melting prilling by twin-screw extruder followed and molding by the single screw extrud-er. The mechanical properties of composite of wheat straw and thermoplastic were measured . The results indicated that adding a small amount of wheat straw powder caused the reduction of mechanical properties of wood plastic composite,the mechanical properties of wood plastic composite increased with increasing wheat straw powder content,mechanical properties de-creased when the content of wheat straw was more than a certain percentage,especially,the impact property decreased obviously;the test indicated that the mechanical properties of HDPE were higher than PP.

  7. The effects of particle size and content on the thermal conductivity and mechanical properties of Al2O3/high density polyethylene (HDPE composites

    Directory of Open Access Journals (Sweden)

    2011-07-01

    Full Text Available The influences of filler size and content on the properties (thermal conductivity, impact strength and tensile strength of Al2O3/high density polyethylene (HDPE composites are studied. Thermal conductivity and tensile strength of the composites increase with the decrease of particle size. The dependence of impact strength on the particle size is more complicated. The SEM micrographs of the fracture surface show that Al2O3 with small particle size is generally more efficient for the enhancement of the impact strength, while the 100 nm particles prone to aggregation due to their high surface energy deteriorate the impact strength. Composite filled with Al2O3 of 0.5 µm at content of 25 vol% show the best synthetic properties. It is suggested that the addition of nano-Al2O3 to HDPE would lead to good performance once suitably dispersed.

  8. Caracterización de unidades biofísicas a partir de indicadores ambientales en Milpa Alta, Centro de México

    Directory of Open Access Journals (Sweden)

    María de Lourdes Rodríguez Gamiño

    2006-01-01

    Full Text Available En este trabajo se delimitaron y caracterizaron a las unidades biofísicas a partir de indicadores ambientales en Milpa Alta, Centro de México. Se trazaron las unidades geomorfológicas morfogenéticas que sirvieron de base para la caracterización de las unidades ambientales biofísicas (UAB. Se llevaron a cabo recorridos de campo para la verificación de las UAB y para la toma de muestras de suelos y levantamientos botánicos. En laboratorio se determinaron las propiedades físicas y químicas de los suelos. Se determinaron los indicadores de los factores de relieve, suelo, cobertura vegetal y uso de suelo. Las UAB se caracterizaron considerando los indicadores de relieve, pendiente y altitud; clima, temperatura y precipitación; suelo, humedad, materia orgánica, densidad aparente, pH; vegetación, densidad de la cobertura vegetal y uso de suelo. Las unidades se caracterizan por ser de origen endógeno volcánico acumulativo de flujos lávicos. Los tipos de relieve que predominan en los sitios muestreados son laderas de montaña superiores, medias e inferiores, de flujos lávicos; laderas de montaña superiores, internas y externas, de cono cinerítico; laderas superiores e inferiores de lomeríos medios y bajos; piedemonte acumulativo local; piedemonte acumulativo de lomeríos medios y bajos y planicie aluvial. La caracterización de las UAB mediante los indicadores ambientales permite contar con información básica para la toma de decisiones en el manejo adecuado de los recursos naturales y en la planeación socioambiental.

  9. Study of mechanical and morphological properties of bio-based polyethylene (HDPE) and sponge-gourds (Luffa-cylindrica) agroresidue composites

    Science.gov (United States)

    Escocio, Viviane A.; Visconte, Leila L. Y.; Cavalcante, Andre de P.; Furtado, Ana Maria S.; Pacheco, Elen B. A. V.

    2015-05-01

    Brazil has a remarkable position in the use of renewable energy. The potential of natural resources in Brazil has motivated the use of these renewable resources to make technologies more sustainable. From the large variety of commercially available High Density Polyethylene (HDPE) from different sources, two were chosen for investigation: one produced from sugarcane ethanol, and the other one, a conventional polyethylene, produced from fossil resources. In the preparation of the composites, sponge-gourds also called Luffa cylindrica were selectec. The main application of this product is as bath sponge, whose production generates scraps that are generally burnt. In this work, the composites were prepared by blending the sponge scrap at different proportions (10, 20, 30 and 40% wt/wt) with high density polyethylene (HDPE) from renewable source by extrusion. The melt flow index analysis of the composites was determined and specimens were obtained by injection molding for the assessment of mechanical properties such as tensile (elasticity modulus), flexural and Izod impact strengths. The microstructure of the impact fractured surface of the specimen also was determined. The results showed that the addition of sponge scrap affects positively all the properties studied as compared to HDPE. The results of tensile strength, elasticity modulus and flexural strength were similar to those observed in the literature for composites of HDPE from fossil source. The microstructure corroborates the results of mechanical properties. It was shown that the sponge scrap has potential to be applied as cellulosic filler for renewable polyethylene, providing a totally renewable material with good mechanical properties.

  10. Synergistic effect of combination of Irganox 1010 and zinc stearate on thermal stabilization of electron beam irradiated HDPE/EVA both in hot water and oven

    International Nuclear Information System (INIS)

    Thermo-oxidative stability of HDPE/EVA blends can be considerably increased by combination of a high-molecular weight phenolic antioxidant and zinc stearate. In this work, the post-irradiation thermal stability of HDPE/EVA blends has been studied. High-density polyethylene and its blends with ethylene-vinylacetate copolymer in both pure form and mixed with Irganox 1010 and zinc stearate were exposed to electron beam radiation at doses between 80 and 150 kGy, at room temperature, in air. In order to evaluate the thermal stability of the samples, post-irradiation heat treatments were done in both hot water bath at 95 deg. C and in an oven at 140 deg. C. The mechanical properties and changes in the chemical structure were determined during thermal aging in hot water and oven. The gel content was enhanced by increasing EVA concentration in all applied doses. The stabilized blends have lower gel content than the unstabilized samples. From the results of heat aging treatments it was observed that the thermal stability of the unstabilized blend samples was lower than HDPE. Thermal stability of the samples has been improved by incorporation of Irganox 1010 and zinc stearate. Formation of hydroxyl group was insignificant for stabilized samples during heat aging in both conditions. Also, the changes in the value of oxidation induction time (OIT) for the stabilized samples were negligible after prolonged immersion in hot water

  11. Alta Velocità e innovazioni tecnologiche e funzionali

    Directory of Open Access Journals (Sweden)

    Emilia Giovanna Trifiletti

    2008-05-01

    Full Text Available La realizzazione di linee e di stazioni dell’Alta Velocità, oltre ad influire sullo sviluppo urbanistico delle aree interessate, sta cambiando radicalmente le relazioni spazio-temporali fra i diversi centri urbani connessi dalla rete del trasporto su ferro. Da un lato sono mutate le funzioni assunte dai contenitori-stazione e dall’altro sta mutando la domanda di trasporto che promuove, per le tratte coperte dalle linee dell’Alta Velocità, il treno rispetto all’aereo e alla macchina. In Italia, sulla scia del modello francese, il Gruppo Ferrovie dello Stato RFI, al fine di rendere più confortevole ed efficiente il viaggio sui treni ad Alta Velocità, ha dotato i nuovi treni di numerose innovazioni tecnologiche. Per quanto riguarda l’utilizzo di nuove tecnologie lungo le linee dell’A.V., l’articolo individua la variazione delle abitudini degli utenti al mutare dell’offerta dei servizi predisposti dalle compagnie trasportistiche. La tecnologia utilizzata sui nuovi treni dell’Alta Velocità cambia dunque il concept del viaggio: il valore aggiunto della tecnologia Wi-Fi introdotta sui treni rende la scelta del trasporto su ferro più produttiva rispetto gli altri modi di trasporto quali la macchina o l’aereo. La finalità dell’articolo è da un lato individuare il ruolo urbano assunto delle stazioni dell’Alta Velocità e dall’altro evidenziare come al mutare dell’offerta di trasporto, in termini di servizi offerti ad alto contenuto tecnologico, muta contestualmente anche la domanda di trasporto sul territorio e come tutto questo incida dunque sul governo delle trasformazioni territoriali. Questo è il nuovo importante ruolo della pianificazione: alcune delle nostre più importanti città stanno radicalmente trasformandosi proprio inserendo nei loro cuori le stazioni dell’Alta Velocità come elementi-chiave di accessibilità, vitale per la competitività in tutti i settori economici. Allo stesso modo le stazioni

  12. Efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (termotratada y micropropagada) de las variedades CP 65-357 y LCP 85-384 Effect of planting date on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated)

    OpenAIRE

    Patricia A. Digonzelli; Eduardo R. Romero; Jorge Scandaliaris; Juan Giardina; Osvaldo Arce

    2005-01-01

    Se evalúa el efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (micropropagada y termotratada) de las variedades CP 65-357 y LCP 85-384, en condiciones de disponibilidad hídrica adecuada. La caña semilla micropropagada y termotratada (50ºC, 2 hs) se plantó, con una densidad de 15 yemas/m, en tres épocas contrastantes: otoño, invierno y primavera. El material empleado estaba libre de escaldadura de la hoja (Xanthomonas albilineans) y achaparramien...

  13. Densidad poblacional y uso del hábitat de la codorniz Moctezuma (Cyrtonyx montezumae) en Hualtepec, Hidalgo

    OpenAIRE

    Lilia Hernández Palafox; Germán David Mendoza Martínez; Juan Ignacio Valdez Hernández; José Luis Alcántara Carbajal; Fernando Clemente Sánchez; Marivel Hernández Téllez

    2007-01-01

    El presente estudio se realizó para determinar la densidad poblacional y el uso del hábitat de la codorniz Moctezuma (Cyrtonyx montezumae) en Hualtepec, Hidalgo, México, en tres tipos de vegetación: bosque, pastizal y zona de transición (ecotono). Dicho sitio se localiza en el extremo oeste de Hidalgo, con área de muestreo de 5 715 ha. Se realizó un muestreo en 55 unidades, para evaluar el uso del hábitat por medio de indicios (excretas, rascaderos, plumas y nidos), y densidad de pob...

  14. Caracterización de las densidades en autómatas celulares binarios unidimensionales con retardo

    OpenAIRE

    José Manuel Gómez Soto; McIntosh, Harold V.

    2010-01-01

    La caracterización de las densidades de los autómatas celulares es un tema relevante en el estudio de estos modelos. Los autómatas celulares se han utilizado en muchas aplicaciones tales como la modelación de problemas de dinámica de fluidos, el estudio de materiales magnéticos en el procesamiento de imágenes, etcétera. Una caracterización de la densidad de estos autómatas permite realizar estudios matemáticos más profundos de los fenómenos que simulan. En este trabajo se propone caracterizar...

  15. Estructura metropolitana y funciones de densidad residencial. El caso de la región metropolitana de Barcelona

    OpenAIRE

    Muñiz, Iván; Galindo, Anna

    2006-01-01

    La relación que se establece entre el nivel de densidad residencial y la accesibilidad al lugar de empleo en el interior de una área urbana parece ser más compleja que la supuesta en el Modelo de Ciudad Monocéntrica. Las estimaciones de funciones de densidad residencial más simples, sustentadas en un modelo teórico que suponía una concentración total del empleo en el distrito central y que utilizaban como única medida de accesibilidad la distancia al centro, han dado paso a estimaciones más s...

  16. Variaciones en la densidad del oxígeno en el aire y su influencia sobre la salud humana

    OpenAIRE

    Olcina Cantos, Jorge; Martín Estévez, David

    2012-01-01

    La falta de oxígeno puede conllevar serias consecuencias en la salud de los seres vivos, incluida la muerte. La modificación de su densidad en el aire pueda tener efectos sobre la salud humana, especialmente en grupos de riesgo y personas con afecciones pulmonares o cardiacas previas. Se analiza el efecto de las variaciones en la densidad de oxígeno, originadas por los cambios en las masas de aire presentes en la atmósfera, sobre los ingresos hospitalarios por enfermedad cardiaca y vásculo-ce...

  17. Densidad poblacional del venado cola blanca (Odocoileus virginianus) en sabana inindable de Paz De Ariporo (Casanare), Orinoquia colombiana

    OpenAIRE

    Montenegro Olga Lucía; Pérez Moreno Heidi Yohana

    2006-01-01

    Esta investigación buscó estimar y analizar las diferencias en la densidad poblacional del venado cola blanca
    (Odocoileus virginianus) en dos hatos de la Orinoquia colombiana, con miras a aportar elementos para su manejo
    sostenible en la región. Para la estimación de densidad se realizaron conteos de individuos y grupos en transectos
    lineales de ancho variable acumulando 54,3 km y 48,65 km en los hatos Taparas y Miramar respectivamente.
    Estos recorr...

  18. Densidad poblacional y uso del hábitat de la codorniz Moctezuma (Cyrtonyx montezumae) en Hualtepec, Hidalgo

    OpenAIRE

    Lilia Hernández Palafox; Germán David Mendoza Martínez; Juan Ignacio Valdez Hernández; José Luis Alcántara Carbajal; Fernando Clemente Sánchez; Marivel Hernández Téllez

    2007-01-01

    El presente estudio se realizó para determinar la densidad poblacional y el uso del hábitat de la codorniz Moctezuma (Cyrtonyx montezumae) en Hualtepec, Hidalgo, México, en tres tipos de vegetación: bosque, pastizal y zona de transición (ecotono). Dicho sitio se localiza en el extremo oeste de Hidalgo, con área de muestreo de 5 715 ha. Se realizó un muestreo en 55 unidades, para evaluar el uso del hábitat por medio de indicios (excretas, rascaderos, plumas y nidos), y densidad de población, c...

  19. Variación espacio-temporal de la densidad poblacional de erizo rojo Strongylocentrotus franciscanus (Echinodermata: Echinoidea: Strongylocentrotidae en Baja California Spatial and temporal variation of the population density of the red sea urchin Stronngylocenntrotus franciscanus (Echinodermata: Echinoidea: Strongylocentrotidae in Baja California

    Directory of Open Access Journals (Sweden)

    Julio S. Palleiro-Nayar

    2012-04-01

    Full Text Available Se estimó la densidad poblacional de erizo rojo, Strongylocentrotus franciscanus, en 10 localidades de la costa occidental de Baja California, México, donde se realiza la extracción comercial de este recurso pesquero. Se compararon las estimaciones realizadas en cuatro años muestreados: 2003, 2005, 2006 y 2008. Las variaciones observadas en las localidades analizadas indicaron diferencias espacio-temporales para la densidad de erizo rojo y diferencias en la estructura de tallas, las cuales estuvieron influenciadas principalmente por la intensidad de la pesca y al esporádico reclutamiento en cada sitio. Se encontraron dos localidades (Isla San Jerónimo y Arrecife Sacramento que destacaron por presentar una alta densidad de erizo rojo y una amplia estructura de tallas, predominando individuos de tallas entre 50 a 80 mm diámetro de caparazón, lo que podría indicar que la intensidad de pesca aparentemente tiene un menor efecto que en los otros sitios.Density estimations of red sea urchin Strongylocentrotus franciscanus were recorded in ten sites with commercial fisheries on the west coast of Baja California, Mexico. The estimations for the years 2003, 2005, 2006 and 2008 were compared. The variations observed in the study sites indicate important spatial and temporal differences in density and size structure, influenced by fishing intensity and sporadic recruitment in each site. We found two sites (San Jeronimo Island and Sacramento Reef with a high density and wide size structure; with a predominance of individuals of sizes from 50 to 80 mm with lest impact possible in fishing mortality for all sites.

  20. Estabilidad y funcionalidad de sellantes dentales en altas temperaturas ambientales

    OpenAIRE

    Mishina, Anastasia; Mayelín Guerra, Rosa; Durán Ramos, Ivette; Juan D. Sabatier

    2000-01-01

    Los sellantes dentales son materiales que se emplean en estomatología para sellar las fosas y fisuras oclusales de los dientes y evitar la adherencia del estreptococus mutans agente que produce la caries dental. Estos materiales se suministran en dos partes que al mezclarse producen el endurecimiento de la resina. Sin embargo, estos productos presentan dificultades para su comercialización en los países tropicales, debido a que las altas temperaturas ambientales traen problemas en...

  1. Luces y sombras de la lectura en voz alta

    OpenAIRE

    Cassany, Daniel

    2007-01-01

    En el siguiente artículo aborda una práctica tan extendida en las aulas de todos los niveles educativos como es la lectura en voz alta. A partir de su experiencia personal y profesional, formula un análisis ameno, provocador y fundamentado, una constante en sus textos y conferencias, que suscitará en el lector docente nuevas perspectivas acerca de su trabajo.

  2. Cuaderno de Prácticas: Altas Capacidades

    OpenAIRE

    García Fernández, José Manuel; Vicent Juan, Maria; Gonzálvez Macià, Carolina

    2016-01-01

    Este material, centrado en el estudio de las Altas Capacidades, pretende favorecer la adquisición de destrezas en el conocimiento e intervención en el ámbito de la educación especial para conocer de primera mano las diferentes formas que se tienen para actuar e intervenir ante niños con necesidades específicas de apoyo educativo.

  3. Los colosos del campo: tractores de alta potencia

    OpenAIRE

    Moya Gonzalez, Adolfo; Diezma Iglesias, Belen

    2014-01-01

    Revisión y descripción de las principales características de los tractores de alta potencia en el sector agrícola español. La agricultura profesional es una empresa compleja y la inversión en formación de los agentes implicados en el sector (agricultores e ingenieros) es la llave para conseguir aprovechar toda la tecnología disponible y optimizar los recursos usados.

  4. Cócs. Hallmark of the Terra Alta

    Directory of Open Access Journals (Sweden)

    Maria Del Loreto Meix

    2004-04-01

    Full Text Available This article looks at the traditional cake making in the Terra Alta (Catalonien area linked to festivities, and in particular the pastries usually made. In this area the pastries are known as cócs, a word common to Terra Alta and the neighbouring districts of Ribera d'Ebre and the Priorat. Locally produced mistelle, sweet or rancid wine is served with the pastries. Nowadays, the bakeries and cake makers in the area's towns and villages also produce traditionally crafted products, that used only to be homemade.The article, resulting from the final degree project produced by the author for her Humanities degree at the UOC, offers a privileged look at the richness of the Terra Alta in terms of its gastronomic history, customs and its high regard for its cakes. The author, who has previous experience in the field, places the specific aspects of Terra Alta cake making in the context of the Mediterranean cultures with common roots dating back to the ancient and medieval worlds and which still have an easily identifiable "family feel", whilst looking, from an ethnographic point of view, at what she calls the "world of wheat" in the area, (the dough for bread, the craft of the baker, the ovens and other tools, and the associated traditions, among other things. In short, she rescues a living part of the local day-to-day activities and places it under the microscope of food history, whilst providing information that may well be of interest for study from other points of view.

  5. Caracterización morfométrica de la cuenca alta del río Sauce Grande.

    Directory of Open Access Journals (Sweden)

    Fernanda Julia Gaspari

    2013-01-01

    Full Text Available La cuenca alta del río Sauce Grande abastece el complejo hidráulico Embalse Paso de las Piedras, comportándose como servicio ambiental primordial para el consumo hídrico de Bahía Blanca. El análisis de las características morfométricas y funcionales de una cuenca hidrográfica a través de parámetros de forma, relieve y red de drenaje, es básico en la modelación hidrológica para determinar el movimiento y captación del agua de lluvia. Estos indicadores pueden apoyar una formulación de un Sistema de Pago por Servicios Ambientales, como estrategia básica de ordenamiento territorial y desarrollo local, centrado en la oferta de agua generada por la cuenca. El objetivo fue caracterizar morfométricamente la cuenca alta del río Sauce Grande. La metodología aplicada se basó en establecer y analizar los parámetros morfométricos mediante el uso de Sistemas de Información Geográfica y planillas de cálculo, a partir de un modelo digital del terreno e imágenes satelitales. Los resultados alcanzados definieron que la cuenca posee un área de 1502.6 km2. La longitud axial es de 41.6 km con un ancho promedio de 36.1 km. El Factor de forma (0.87 indica que posee forma alargada, siendo rectangular oblonga según el coeficiente de compacidad de Gravelius (2.8. La longitud del cauce principal es 58.34 km con pendiente media de 0.48 %. La densidad de drenaje es 0.27 km.km-2 y su coeficiente de sinuosidad 1.42. El tiempo de concentración es 11.8 hs. La curva hipsométrica adimensional corresponde a una cuenca con un avanzado grado de desarrollo. Todos estos parámetros facilitan la cuantificación del caudal líquido en la cuenca.

  6. Investigation of Time Effect on Resistivity Variation of 10 MeV Electron Beam Irradiated LDPE and HDPE

    International Nuclear Information System (INIS)

    Charges occur in both the physical and/or chemical nature and concentration of defects in the crystalline region, and traps at chain fold-amorphous interfaces. In this work attempt has bean made to investigate the time effect on the variation of surface and volume resistivity of the LDPE and HDPE samples were irradiated under the 10 MeV electron beam of Rhodotron accelerator. In fact, the aim was to investigate these variations during about one mount after irradiation which is changing due to the charge storage in the polyethylene. The samples were prepared in sheet form with the thickness of 0.6±0.1 mm and irradiated at the dose range of 70 to 370 kGy. All the samples were kept at room temperature in laboratory. The results show an increment at about 25 days after irradiation in surface resistivity and decreasing later on for all the samples. The results of volume resistivity measurements didn't show any significant variation

  7. Characterization of the crystal orientation in mono-oriented films of HDPE/LLDPE blends by IR dichroism

    Science.gov (United States)

    Canevarolo, Sebastião V.; Elias, Marcelo; Ravazzi, Camila; Silva, Jorge

    2016-03-01

    Polyethylene films are a common packaging material. The level and type of chain orientation in these films are a very important property which is of great care and concern of the converter personnel during the conformation process. Usually bi-orientation is the conventional procedure but when easy tear in one direction is needed mono-orientation is sought. This paper deal with the characterization of the crystalline orientation in films of polyethylene blends (HDPE/LLDPE) which have being oriented in two steps: initially the polymer was bi-oriented via extrusion-blown, cooled, and then in a second process hot stretched along the machine direction in order to produce mono-oriented films. In order to evaluate the orientation of the film, the polarization of the FT-IR beam was rotated 360° in steps of 5° by rotating the polarizer. In each step the absorbance spectrum was recorded and the corresponding dichroic ratio (DR) calculated after subtracting the baseline. With differential scanning calorimetry (DSC) was possible to infer about the changes in the morphology caused by the stretching.

  8. Effect of Rice Husk Surface Modification by LENR the on Mechanical Properties of NR/ HDPE Reinforced Rice Husk Composite

    International Nuclear Information System (INIS)

    Surface modification of rice husk (RH) with alkali pre-treatment (NaOH solution 5 % w/ v) was carried out at the initial state to investigate the effect of surface treatment of fibre on the surface interaction between fibre and rubber. Further modification of RH surfaces after alkali treatment was using Liquid Epoxidized Natural Rubber (LENR) coating at three concentrations, 5 %, 10 %, and 20 % wt LENR solution in toluene. Interfacial morphology and chemical reactions between RH fibre and rubber were analyzed by FTIR and Scanning Electron Microscope (SEM). It was found that 10 % wt LENR solution gave the optimum interaction between fibre and rubber. Matrix and composite blends derived from 60 % natural rubber (NR), 40 % high density polyethylene (HDPE) reinforced with RH fibre were prepared using an internal mixer (Brabender Plasticoder). Result showed that pre-treatment of RH treated with 5 % NaOH followed by treatment with 10 % LENR solution given the maximum interaction between fibre and matrix that gave rise to better mechanical properties of the composites. (author)

  9. Weather, cultivar and density-dependent processes influence on aphid in alfalfa Influência do clima, da cultivar e de processos dependentes da densidade sobre afídeos em alfafa

    Directory of Open Access Journals (Sweden)

    Alexandre de Almeida e Silva

    2007-01-01

    Full Text Available It is important to understand the effects of weather, insect density and plant cultivar on insect abundance to predict and prevent crop production loss. The present work investigated the influence of such factors on aphid in alfalfa during one year (short term. Data was collected from September/1997 to August/1998 at Canchin Farm (CCPSE-EMBRAPA, São Carlos, State of São Paulo, Brazil. Weather conditions had, in general, little effect on the variation of aphid populations, but Therioaphis maculata abundance was negatively correlated to humidity. Moreover, high maximum temperatures and low levels of rainfall possible favored T. maculata high abundance on Crioula and P3 cultivars. Therefore, appropriate management of this species is required during hot and dry periods. Population variation of Acyrthosiphon spp., T. maculata and Aphis craccivora seems to be regulated by density dependent processes. Resistant cultivar CUF 101 had a lower abundance of T. maculata and A. craccivora and a narrower population variation than the other cultivars and may reduce their abundance on field. Long-term studies on population dynamics including the effect of climatic conditions and density-dependent factors on plant quality will contribute to pest management in alfalfa fields.É importante entender os efeitos do clima, da densidade dos insetos e da cultivar sobre a abundância de insetos para se predizer e prevenir perdas na produção das culturas. O objetivo do presente trabalho foi analisar a influência desses fatores sobre afídeos em alfafa no período de um ano. Os dados foram coletados de setembro/1997 a agosto/1998 na Fazenda Canchin (CPPSE-EMBRAPA, São Carlos, São Paulo, Brasil. As condições climáticas, em geral, tiveram pequeno efeito sobre a variação populacional dos afídeos, mas a abundância de Therioaphis maculata esteve negativamente correlacionada à umidade. Além disso, as altas temperaturas máximas e os baixos níveis de precipita

  10. CRECIMIENTO Y PRODUCTIVIDAD DE CHAYA (Cnidoscolus chayamansa MCVAUGH, EUPHORBIACEAE) CON DENSIDAD DE PLANTACIÓN VARIABLE

    OpenAIRE

    Jesús Mao E. Aguilar Luna; Pedro A. Macario Mendoza; Esperanza Huerta Lwanga; Salvador Hernández Daumás; Ramiro de Alba Becerra; Eduardo García Villanueva

    2011-01-01

    Se evaluó el efecto que tiene la competenciainterespecífica en el crecimiento y la productividad de la chayacon densidad de plantación (DP) variable, en un suelocalcimórfico de tipo rendzina negra en Noh-Bec, Quintana Roo,México. La chaya se estableció a 1.50 x 3.00 m, utilizando estacassin hojas; se asoció con árboles jóvenes (menores de dosaños) de Cedrela odorata y Citrus latifolia en un diseño deplantación en círculo 'Nelder' de 3154 m2. Se establecieron ochoDP de 2602 a 3772 plantas.ha-1...

  11. EFECTO DEL RALEO SOBRE EL CRECIMIENTO Y LA DENSIDAD DE LA MADERA DE Pinus taeda IMPLANTADO EN MISIONES, ARGENTINA

    Directory of Open Access Journals (Sweden)

    Rodolfo Martiarena

    2014-01-01

    Full Text Available El mayor incremento en crecimiento de la plantación puede causar variación en las propiedades físicas de la madera, pudiendo disminuir la calidad de la misma para la industria. El objetivo del presente trabajo es evaluar el efecto de los tratamientos de raleo sobre el crecimiento y densidad de la madera de Pinus taeda implantado en Misiones, Argentina (25º 59’S - 54º24’O. La plantación se estableció en 1985 con densidad inicial de 1644 pl.ha -1 y se manejó con tres intensidades de raleo (0, 33 y 66 % del área basal del testigo sin ralear, bajo un diseño de bloques completos al azar (3 bloques. A los 20 años se efectuó tala rasa, cuyas densidades eran 711 (0 %, 364 (33 % y 122 (66 % plantas por hectárea, momento en el cual se seleccionaron 45 árboles para determinar la densidad básica de la madera. La misma se determinó a través de la realización de 2.700 probetas. El crecimiento de la plantación fue afectado por la intensidad de raleo, registrando diámetros promedio de 28,7, 34,8 y 45,9 cm, respectivamente, en los tratamientos 0, 33 y 66 % de raleo. El volumen de la plantación, al momento del apeo, fue superior en el tratamiento sin raleo, no obstante el tratamiento 66 % de raleo generó mayor cantidad de madera de grandes dimensiones. La densidad básica como promedio simple y ponderado por volumen no presentó diferencias significativas entre tratamientos. Los valores de densidad ponderada fueron de 0,406, 0,418 y 0,420 g.cm -3 para los tratamientos 0, 33 y 66 % de raleo, respectivamente, mientras que el análisis de correlación entre diámetro y densidad no fue significativo. El estudio mostró que la intensidad de raleo puede ser manejada para maximizar la producción, manteniendo idéntica la calidad de la madera para la industria.

  12. Parâmetros sangüíneos de pacu Piaractus mesopotamicus (Holmberg, 1887 alimentados com dietas suplementadas com cromo trivalente em duas densidades de estocagem - DOI: 10.4025/actascianimsci.v29i4.1019 Hematological parameters of pacu Piaractus mesopotamicus (Holmberg, 1887 fed diets supplemented with trivalent chromium in two stocking densities - DOI: 10.4025/actascianimsci.v29i4.1019

    Directory of Open Access Journals (Sweden)

    Flávio Ruas de Moraes

    2008-03-01

    Full Text Available O objetivo deste trabalho foi avaliar os efeitos da suplementação com cromo trivalente (0, 6, 12 e 18 mg kg-1 de ração sobre as variáveis hematológicas de Piaractus mesopotamicus, mantidos em duas densidades de estocagem (4 e 20 kg m-3. Os mantidos na maior densidade e alimentados com dietas suplementadas com 0 e 6 mg de cromo kg-1 apresentaram redução do número de linfócitos circulantes, sugerindo má adaptação a essa condição de alta densidade. Nas dietas suplementadas com 12 e 18 mg kg-1, tal efeito não foi observado, porém verificou-se aumento do número de trombócitos no tratamento com 12 mg de cromo kg-1. A inexistência de diferença significativa entre os tratamentos, aos 30 dias, sugere a adaptação dos peixes ao tipo de alimento e à situação de alta densidade. Portanto, nas condições deste ensaio, a suplementação com 12 e 18 mg de cromo kg-1 é interessante como estratégia alimentar durante 15 dias.This work evaluated the effects of chromium supplementation on the hematological parameters of Piaractus mesopotamicus Holmberg, 1887 maintained in two stocking densities. Fish were fed diets supplemented with 0, 6, 12 and 18 mg trivalent chromium kg-1 dry ration and maintained at 4 and 20 kg m-3. The fish under high stocking density and fed diets supplemented with 0 and 6 mg kg-1 showed reduction in the number lymphocytes, which suggests non-adaptation to this condition of high density. This was not observed in fish fed diets supplemented with 12 and 18 mg chromium kg-1, but an increase in the number of thrombocytes was evident. The lack of difference between treatments after 30 days may suggest a possible adaptation of fish to the situation. It can be added that supplementation with 12 and 18 mg chromium kg-1 is an interesting feeding strategy for a period of 15 days.

  13. Espaçamento, densidade populacional e adubação nitrogenada na cultura do milho Row spacing, population density and nitrogen fertilization in maize

    Directory of Open Access Journals (Sweden)

    José Pedro Ribeiro do Amaral Filho

    2005-06-01

    Full Text Available A distribuição espacial de plantas por área é um recurso para aumentar a produtividade. Para materiais de alta produtividade, são necessárias mais informações quanto à resposta à adubação nitrogenada. Assim, avaliou-se na cultura do milho a influência do espaçamento, da densidade populacional e de doses de nitrogênio no teor de nitrogênio nas folhas, estimativa do teor de clorofila, número de grãos por espiga, massa de 1.000 grãos, produtividade e teor de proteína nos grãos. O trabalho foi instalado no ano agrícola 2000/2001 e constou de tratamentos representados pela combinação de dois espaçamentos entre as linhas (0,80 e 0,60 m com três densidades populacionais (40, 60 e 80.000 plantas ha-1 e quatro doses de nitrogênio em cobertura (0, 50, 100 e 150 kg ha-1 N. O aumento na doses de N em cobertura promoveram acréscimo no teor de N foliar, na estimativa do teor de clorofila, no número de grãos por espiga, na massa de 1.000 grãos, na produtividade e no teor de proteína nos grãos de milho. A maior produtividade de grãos foi obtida de acordo com as doses crescentes de N em cobertura juntamente com o espaçamento entre as linhas de 0,80 m e 80.000 plantas ha-1.The alteration of spatial distribution of plants is an option to increase the grain yield. For high-yielding materials more information about the influence of nitrogen fertilization is needed. Thus, the influence of row spacing, population densities and nitrogen rates on the leaf nitrogen concentration, estimated concentration of chlorophyll, number of grains per ear, mass of thousand grains, grain yield, and protein content were evaluated. This study was carried out in the 2000/2001growth season; the treatments were two row spacings (0.60 and 0.80 m; three population densities (40,000, 60,000 and 80,000 plants ha-1 and four nitrogen rates (0, 50, 100, and 150 kg ha-1 N. Increased nitrogen rates in top dressing led to a increase in the leaf nitrogen and

  14. Fitomorfologia e produção de cultivares de trigo duplo propósito em diferentes manejos de corte e densidades de semeadura Phytomorphology and production of dual purpose wheat with different cutting regimes and seeding density

    Directory of Open Access Journals (Sweden)

    Thomas Newton Martin

    2010-08-01

    Full Text Available A diversificação de cultivares e finalidades da cultura do trigo podem alterar as indicações de manejo no sistema de integração lavoura-pecuária. Dessa forma, este trabalho tem como objetivo verificar o desempenho das cultivares de trigo duplo propósito em diferentes densidades de semeadura, com e sem corte. As cultivares de trigo utilizados foram: 'BRS Figueira', 'BRS Guatambu', 'BRS Tarumã' e 'BRS Umbu', e as densidades de semeadura utilizadas foram de 50, 200, 350, 500 e 650 sementes por metro quadrado. As variáveis fitomorfológicas e de produção possuem um desempenho diferenciado conforme a cultivar, o manejo e a densidade de semeadura. A cultivar 'Figueira' possui o maior potencial produtivo dentro dos limites de densidades estudados quanto à produção de massa seca, em relação aos demais cultivares. A produção de grãos teve interação significativa entre as cultivares e o manejo (com e sem corte. As cultivares com maiores produções de grãos foram, respectivamente, 'Figueira', 'Umbu', 'Tarumã' e 'Guatambu' no manejo sem corte, já no sistema com corte a cultivar 'Tarumã' foi a que obteve o maior rendimento de grãos, diferenciando-se das demais. A maioria das correlações altas e significativas ocorreu nos manejos com e sem corte. O corte diminuiu todos os valores dos componentes de rendimento, bem como a produção de grãos de todos as cultivares.The diversification of cultivars and purposes of wheat crop may alter the information management system of crop-livestock integration. Therefore, this research has the objective to verify the performance of dual purpose wheat with different cutting regimes and seeding density. The whet cultivate used were: 'BRS Figueira', 'BRS Guatambu', 'BRS Tarumã' and 'BRS Umbu'. The seeding density was of 50, 200, 350, 500 and 650 seeds for square meter. The phitomorfological and production variables have a different performance depending on as cultivar, management and seeding

  15. Use of solaria to predict weed density and floristic composition in no-till cropping systems Uso de solaria na predição da densidade de ervas daninhas e da composição florística no sistema de semeadura direta

    Directory of Open Access Journals (Sweden)

    Pablo Antonio Calviño

    2006-03-01

    a densidade de espécies com densidades altas e baixas de indivíduos em áreas de 10 ha com o uso apenas de cinco solaria. Espécies com baixas densidades tornam o método particularmente útil para ajudar a decidir o uso ou não de herbicidas para evitar a contaminação da terra.

  16. TransForm: TransAlta 2000 annual report

    International Nuclear Information System (INIS)

    Financial information from TransAlta Corp. was presented along with a review of their operations throughout 2000 and a summary of the how the electric utility is doing in terms of power generation, independent power producers, transmission and energy marketing. The utility has changed from a regulated vertically integrated utility into one of Canada's largest non-regulated electric power generators. The utility sold its retail businesses in Alberta and New Zealand and now focuses on coal and hydro generation, gas generation, high-voltage transmission and energy marketing. The newly constructed Centralia, Washington generation facility was brought on line with 1,340 MW in May 2000, on time and on budget. This was the platform to diversify their generation into the United States. The utility reported a solid financial year with $177.9 million in earnings from continuing operations, an 83 per cent increase from 1999, driven mostly by the results of Centralia and power marketing and trading businesses. A financial loss was suffered when the Wabamum power plant in Alberta was shut down for several months to repair a boiler. The utility made excellent progress toward their goal of 15,000 megawatts by 2005 by starting with the construction of what will be one of Canada's largest cogeneration facilities at Sarnia, Ontario. TransAlta also commissioned a 360 MW cogeneration facility at Poplar Creek at Suncor's Fort McMurray oil sand facility. TransAlta also has an excellent track record in developing power generation projects internationally. refs., tabs., figs

  17. Alta disponibilidad para componentes de fabricación

    OpenAIRE

    Maciá Pérez, Francisco; Marcos Jorquera, Diego; Gilart Iglesias, Virgilio

    2006-01-01

    A medida que las tecnologías de la información van calando en el tejido productivo industrial, tanto más compleja se vuelve su organización. Es imprescindible introducir sistemas de gestión proactivos y autogestionados que aseguren su funcionamiento continuado y, en consecuencia, la continuidad en el negocio. En este artículo se propone un sistema de regeneración de los elementos de producción industrial que traslada el concepto de alta disponibilidad a los niveles de fabricación de la organi...

  18. Comportamiento a alta temperatura de paneles de cemento de magnesio

    OpenAIRE

    Tapia García, Mario

    2015-01-01

    El objeto principal de este proyecto final de máster es analizar el comportamiento a altas temperaturas de paneles de cemento de magnesio. Para completar el estudio se realiza un comparativo con paneles de alma de yeso, utilizados habitualmente en construcción. Dado su alto contenido en Cloruro de Magnesio, se marca como objetivo paralelo determinar si la dosificación de los diferentes componentes condiciona la cantidad de HCl emitido. Por último, se investiga la existencia de normas de refer...

  19. Endoscopia digestiva alta :análise de 100 exames

    OpenAIRE

    Afonso, Sofia Isabel Sousa

    2012-01-01

    Objetivo: Aplicando as indicações da American Society for Gastrointestinal Endoscopy (ASGE), um dos objetivos deste estudo foi avaliar o uso apropriado da Endoscopia Digestiva Alta (EDA) e a sua relação com os achados endoscópicos. A taxa de complicações e do uso da anestesia, as principais dificuldades, a tolerância e satisfação dos doentes também foram alvo de análise neste estudo. Métodos: Para este estudo prospetivo foram obtidos dados de 100 casos através de um inquérit...

  20. MCU para multiconferencias en alta definición

    OpenAIRE

    López Rubio, Javier

    2007-01-01

    En este trabajo se describen todos los pasos seguidos para el desarrollo de una MCU (Multipoint Control Unit), capaz de gestionar videoconferencias de alta definición. En el se incluyen las especificaciones y el diseño tanto a nivel de arquitectura como a nivel de aplicación. La MCU resultante es el resultado de la investigación que la fundación i2Cat, encargó al grupo de investigación de banda ancha del departamento de ingeniería telemática. Este trabajo se encuentra inclui...

  1. Vulnerabilidad en la cuenca alta del rio Lerma

    OpenAIRE

    Cedeño Valdiviezo, Alberto; Torres Lima, Pablo

    2013-01-01

    La subcuenca Alta del Río Lerma en el Estado de México, importante abastecedor de agua para la Ciudad de México, ha estado expuesta a una fuerte contaminación en los últimos años, misma que ha tenido como consecuencia el Cambio Climático y los consecuentes problemas de salud pública que se están manifestando de diferentes maneras. No obstante, el Estado Mexicano insiste en seguir apoyando a empresas trasnacionales asociadas al cultivo de transgénicos, producción de plaguicidas, pesticidas y P...

  2. Sistemi di alimentazione della rete Alta Val Tiberina

    OpenAIRE

    Cattaneo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Alema, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; Frapiccini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Marzorati, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; Monachesi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia

    2011-01-01

    Nell’ambito del progetto FIRB-Airplane [“Piattaforma di ricerca multidisciplinare su terremoti e vulcani”, fondi MIUR 2007-2011 responsabili: Cocco, Amato e Stucchi1] dalla seconda metà del 2009 è stata installata una rete densa di stazioni sismiche nell’area dell’Alta Val Tiberina (AVT, Figura 1), i cui dati in continuo vengono trasmessi alla sede di Ancona del CNT attraverso una dorsale Wi-Fi HYPERLAN [Monachesi e Cattaneo, 2010]. La rete è stata progettata cer...

  3. Matrices estructuradas y alta precisión relativa

    OpenAIRE

    Barreras Peral, Álvaro; Peña Ferrández, Juan Manuel

    2014-01-01

    Esta memoria se enmarca, dentro del Algebra Lineal Numérica, en el campo de estudio de métodos numéricos adaptados a clases de matrices con estructura especial, que es un campo que muestra una intensa y creciente actividad investigadora. Concretamente, considerará clases de matrices para las que se encontrarán métodos numéricos cuyo cálculo se podrá llevar a cabo con alta precisión relativa. Conseguir cálculos precisos es una propiedad muy deseable para cualquier método numérico. El ideal es ...

  4. Proyecto de Historia como respuesta educativa a las altas capacidades

    OpenAIRE

    Miguel Yoldi, Yohanna

    2014-01-01

    Este trabajo presenta una propuesta de intervención en el aula que responde a las necesidades educativas del alumnado con altas capacidades, desde una escuela inclusiva. Para realizarlo, nos hemos basado en dos autores: Roger J. Sternberg y Joseph S. Renzulli, que no sólo definen las características y necesidades educativas de este colectivo, sino que también proponen posibles respuestas que respondan a su forma de aprender. Desde el área de Ciencias Sociales, apostamos por el aprendizaje bas...

  5. Todos iguales, todos diferentes. Altas capacidades en el aula.

    OpenAIRE

    Soloaga Martín, Beatriz

    2012-01-01

    El presente trabajo se centra en el alumnado de altas capacidades y las posibilidades de atención en el marco del modelo de escuela inclusiva. Se comienza explicando las características de estos alumnos, los estereotipos que existen sobre ellos y las disincronías que es frecuente encontrar en su desarrollo. Se sigue la clasificación de varios autores para distinguir entre superdotación y talento viendo las diferencias significativas que existen entre ellos. De forma breve se ha...

  6. Assessment of NDE Methods on Inspection of HDPE Butt Fusion Piping Joints for Lack of Fusion with Validation from Mechanical Testing

    International Nuclear Information System (INIS)

    Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, are being conducted to evaluate nondestructive examinations (NDE) coupled with mechanical testing of butt fusion joints in high-density polyethylene (HDPE) pipe for assessing lack of fusion. The work provides information to the U.S. Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques of HDPE butt fusion joints in Section III, Division 1, Class 3, buried piping systems in nuclear power plants. This paper describes results from preliminary assessments using ultrasonic and microwave nondestructive techniques and mechanical testing with the high-speed tensile impact test and the side-bend test for determining joint integrity. A series of butt joints were fabricated in 3408, 12-in. IPS DR-11 HDPE material by varying the fusion parameters to create good joints and joints containing a range of lack-of-fusion conditions. Six of these butt joints were volumetrically examined with time-of-flight diffraction (TOFD), phased-array (PA) ultrasound, and the Evisive microwave system. The outer-diameter weld beads were removed for the microwave inspection. In two of the four pipes, both the outer and inner weld beads were removed and the pipe joints re-evaluated. The pipes were sectioned and the joints destructively evaluated with the side-bend test by cutting portions of the fusion joint into slices that were planed and bent. The last step in this limited study will be to correlate the fusion parameters, nondestructive, and destructive evaluation results to validate the effectiveness of what each NDE technology detects and what each does not detect. The results of the correlation will be used in identifying any future work that is needed.

  7. MODELAGEM DE MISTURAS NA FABRICAÇÃO DE COMPÓSITOS POLÍMERO-FIBRA, UTILIZANDO POLIETILENO E SERRAGEM DE Pinus sp.

    Directory of Open Access Journals (Sweden)

    Karla Pocai

    2006-07-01

    Full Text Available Neste trabalho, foi estudado o efeito da composição de diferentes misturas de polietileno de alta densidade (HDPE virgem, HDPE reciclado e serragem de Pinus sp., nas propriedades físico-mecânicas de placas confeccionadas pelo processo de compressão. As misturas foram homogeneizadas em um misturador tipo Drais, sem controle de temperatura e moldadas por compressão em prensa hidráulica a 150oC. Partindo das placas, foram confeccionados corpos-de-prova para ensaios de tração, flexão, impacto e dureza, segundo normas ASTM, e também foram determinadas as densidades médias das placas. A modelagem estatística foi realizada segundo o planejamento centróide simplex, utilizando sete misturas dos três componentes e três repetições de cada mistura. Os resultados mostraram que a resistência à tração, a resistência à flexão, a dureza e a densidade das placas, são explicadas pelo modelo linear, enquanto a resistência ao impacto é explicada pelo modelo quadrático. Não houve diferença significativa nas propriedades físico-mecânicas dos compósitos confeccionados com HDPE virgem, daqueles confeccionados com HDPE reciclado, exceto para resistência ao impacto, no qual o HDPE virgem apresentou maiores valores.

  8. Construction Application of HDPE Pipe in Municipal Drainage Engineering%市政排水工程中HDPE管的施工应用

    Institute of Scientific and Technical Information of China (English)

    王端喜

    2009-01-01

    该文结合工程实践经验,详细论述了HDPE管的性能特点,及其在市政排水工程中的施工工艺过程,并提出了施工中应注意的若干问题.%Combined with the engineering practical experience, the article discusses in detail the performance characteristics of HDPE pipe and its construction technological process in the municipal drainage project, and puts forward the some caution for attention in the construction.

  9. Studi Pembuatan Komposit Termoplastik Elastomer Dari HDPE Bekas Dan Karet EPDM Dengan Pengisi serbuk Tandan Kosong Kelapa Sawit Dengan Pendispersi Gliserol Monostearat

    OpenAIRE

    Ashari, Dian

    2016-01-01

    Dynamic vulcanization has been done on the mixtureTPE HDPE-Rubber EPDM filled oil palm empty fruit bunches at a temperature of 175 0C with variations addition of glycerol monostearate 0; 2; 4; 6; 8; 10 g. Then molded into specimens by means of pressing the compressor at a temperature of 175oC in according with ASTM D638 specimens were characterized by a tensile strength test , test sound absorption coefficient and analysis of surface morphology by SEM. The results showed that the mixture of T...

  10. Alta parasitemia pelo Trypanosoma cruzi em paciente com lupus eritematoso sistêmico

    OpenAIRE

    Santos-Neto Leopoldo Luiz dos; Polcheira Máira F.; Castro Cleudson; Lima Rodrigo Aires Corrêa; Simaan César Kozak; Corrêa-Lima Francisco Aires

    2003-01-01

    É descrito um caso de doença de Chagas com alta parasitemia pelo Trypanosoma cruzi em paciente com lupus eritematoso sistêmico. O xenodiagnóstico foi útil na identificação da parasitemia e o benznidazol foi capaz de reduzir a alta e incomum parasitemia. Em indivíduos com doenças auto-imunes e immunossuprimidos, o benznidazol pode ser uma alternativa no controle da alta parasitemia por Trypanosoma cruzi.

  11. Densidades de siembra de dos variedades comerciales de crisantemo, Chrysantemum morifolium Ramat en Piendamo (Cauca

    Directory of Open Access Journals (Sweden)

    Posada D. Adolfo

    1986-09-01

    Full Text Available The behavior and agricultural characteristics of two kinds of Chrysanthemum (White Marble and Yellow Polaris were evaluated in terms of yield and quality of the product. Two different kinds of planting systems were applied (single stem and pinched stem. The experimental design in randomized whole blocks for each variety and system including four density treatments (80, 90, 110 and 115 sterns per 1.05 m2 was repeated six times. The experimental unit was of 2.10 m2; 1.26 m2 were harvested. A strong discrepancy between the quantity and quality of the product was observed. The highest yields were obtained with densities of 110 and 115 stems per 1.05 m2. However, the experimental units dis not always met both requirements of a diameter greater than seven cm and three or more marketable flowers per stem. If maximizing production of acceptable bunches is taken as a decision variable, a density of 90 sterns per 1.05 m2 with a 3/3/2/2/2/3/3 arrangement with pinched stern for Yellow Polar is seems a better alternative. As for White Marble, it would be better to have 80 stems per 1.05 m2 with a 3/2/2/2/2/2/3 arrangement in the single stem, but the probability of acceptance is only 0.666. In addition, White Marble showed more susceptibility to dwarfism.Se evaluó el comportamiento y características agronómicas asociadas con el rendimiento y la calidad del producto en las variedades White Marble y Yellow Polaris, en los sistemas de tallo único y tallo despuntado. El diseño experimental de bloques completos al azar para cada variedad y sistema incluía cuatro tratamientos de densidad (80, 90, 110 Y 115 tallos por 1.05 m2, con seis repeticiones. La unidad experimental fue de 2.10 m2, cosechando 1. 26m2(1.05 x 1.20. Se observó marcado antagonismo entre la cantidad y la calidad del producto comercial. Los mayores rendimientos se obtuvieron con densidades de 110 y 115 tallos por 1.05 m2, pero no siempre la producción cumplía con los requisitos de di

  12. Estudio de la densidad y de la viscosidad de algunos ácidos grasos puros

    Directory of Open Access Journals (Sweden)

    Cedeño González, Fidel Oscar

    1999-10-01

    Full Text Available An experimental study is carried out according to ASTM analysis methods of two physical properties, density and viscosity, of palmitic, stearic and oleic fatty acids; compounds which are present in the deodorization effluents of edible oils, with a view to their physics chemical characterisation needed for the design of surface condensers and freezers that could be employed in the recovery of these effluents. The measures are carried out every 5 °C, from temperatures close to those of solidification in each compound, of great interest in our study, to 100 °C. The values of these properties are contrasted with those that appear in the literature, and the experimental measures are correlated. Values of the density are also obtained applying Rackett's equation and those of dynamic viscosity using Andrade's equation, and then compared with experimental measures. Experimental data of the dynamic viscosity for oleic acid at low temperatures (between 0 and 24 °C are also presented, because of their interest in the design of the previously mentioned equipment.

    En este trabajo se realiza un estudio experimental de acuerdo con los métodos de análisis de la ASTM de las propiedades físicas, densidad y viscosidad en los ácidos grasos palmítico, esteárico y oleico; compuestos que están presentes en los efluentes de la desodorización de aceites comestibles, con vistas a la caracterización físico química necesaria en el diseño de condensadores y congeladores de superficie que pueden aplicarse a la recuperación de estos efluentes. Las medidas se realizan de 5 en 5 °C entre temperaturas muy próximas a las de solidificación en cada compuesto, de gran interés en nuestro estudio, y los 100 °C. Se contrastan los valores de estas propiedades, con los que aparecen en la literatura y se correlacionan las medidas experimentales. También se obtienen valores de la densidad aplicando la ecuación de Rackett y de la viscosidad din

  13. Resultados da conjuntivodacriocistorrinostomia com implante de prótese lacrimal de polietileno de baixa densidade

    Directory of Open Access Journals (Sweden)

    Bison Simone

    2002-01-01

    Full Text Available Objetivos: Estabelecer quais são as complicações pós-operatórias da conjuntivodacriocistorrinostomia (CDCR com implante de prótese lacrimal de polietileno de baixa densidade e relacionar a etiologia da obstrução e o aparecimento destas complicações e, conseqüentemente, o sucesso pós-operatório. Métodos: Foram analisadas 35 vias lacrimais submetidas a conjuntivodacriocistorrinostomia com implante de prótese lacrimal de polietileno. Com a finalidade de estudar as possíveis relações entre as variáveis encontradas (etiologia x complicações e etiologia x sucesso realizou-se o teste exato de Fisher. Resultados: As etiologias de obstrução mais freqüentes foram a dacriocistite crônica e pós-dacriocistorrinostomia que, em conjunto, foram responsáveis por 53,9% dos casos. Os traumatismos ocasionaram 16,3% das obstruções. A taxa de complicações encontrada foi 74,3%. A conjuntivodacriocistorrinostomia apresentou sucesso em uma única intervenção cirúrgica em 9 vias lacrimais (25,7%. Após duas ou mais intervenções cirúrgicas, 17 próteses lacrimais tornaram-se pérvias e bem localizadas (48,6%. O insucesso ocorreu em 9 vias lacrimais (25,7%. Não houve relação estatisticamente significante entre etiologia e ocorrência de complicações nem entre etiologia e sucesso pós-operatório. Conclusões: As complicações encontradas são similares às descritas na literatura e não tiveram relação com a etiologia da obstrução canalicular. O mesmo pode ser considerado no que se refere ao sucesso da conjuntivodacriocistorrinostomia. As vantagens da prótese lacrimal de polietileno de baixa densidade são a grande disponibilidade, a fácil confecção no per-operatório de acordo com o comprimento e o diâmetro do colarete desejados e pode ser substituída pela prótese lacrimal de vidro de borosilicato assim que o edema regrida.

  14. Performance of juvenile turbot (Scophthalmus maximus fed varying dietary L-carnitine levels at different stocking densities Desempenho de juvenis de pregado (Scophthalmus maximus em função da densidade de estocagem e de níveis dietéticos de L-carnitina

    Directory of Open Access Journals (Sweden)

    José Fernando Magalhães Gonçalves

    2010-04-01

    (75,6 ± 2,8 g alimentados durante 75 dias a dois níveis dietéticos de L-carnitina (40 ou 240 mg kg¹. Após esse período, determinou-se a excreção de amônia pós-prandial durante 24 horas. Os peixes cultivados na menor densidade, 4 kg m², apresentaram melhores taxas de crescimento e ganho de peso (94-96 g em comparação aos mantidos em altas densidades (80-87 g. A taxa de eficiência proteica foi mais elevada a 4 kg m² (1,33-1,36, do que a densidades de 8 kg m² (0,98 ou 14 kg m² (0,45. A ingestão voluntária de alimento decresceu de 0,70 para 0,56% do peso corporal com o incremento da densidade. A suplementação de carnitina não afetou o crescimento e a composição corporal, com exceção do conteúdo de carnitine da carcaça que passou de 75 a 128 mg kg¹. Peixes alimentados com suplementos de 240 mg L-carnitina apresentam excreção de amônia mais baixa comparativamente aos alimentados com 40 mg L-carnitina (p < 0,05.

  15. Caracterización de las densidades en autómatas celulares binarios unidimensionales con retardo

    Directory of Open Access Journals (Sweden)

    José Manuel Gómez Soto

    2010-01-01

    La caracterización de la densidad en estos autómatas celulares es importante ya que las transmisiones de señales con retardo están en muchos sistemas de la naturaleza. Entre ellos se encuentra la regularización del gen, las neuronas cerebrales y las señales en cascada en organismos multicelulares. Determinar entonces el comportamiento de la densidad en estos modelos nos dirá más acerca del fenómeno que se simula con ellos y acerca del modelo mismo, obtendremos más información sobre que tan robusto es el espacio temporal, cómo cambia su dinámica y cómo se afecta su capacidad de procesamiento de información.

  16. DENSIDAD Y DISTRIBUCIÓN SOBRE CSMA/CA EN REDES IEEE 802.11G EN MODO AD HOC

    OpenAIRE

    José Domínguez

    2009-01-01

    El propósito principal de la presente investigación, fue determinar la influencia de la densidad y distribución de hosts sobre el control de acceso al medio en redes IEEE 802.11g, tomando como variables fundamentales la densidad y distribución de los mismos y el protocolo CSMA/CA para el acceso al medio de transmisión. La investigación fue de tipo explicativa, con un diseño experimental puro. La misma se basó en los postulados teóricos de Bates (2003), Comer (2000), León García (2001), Sta...

  17. EVALUACIÓN DE DENSIDADES DE PLANTACIÓN EN EL CULTIVO DE LA JAMAICA (Hibiscus sabdariffa L.

    Directory of Open Access Journals (Sweden)

    Z. Terán

    2004-01-01

    Full Text Available La investigación se llevó a cabo en el Instituto Nacional de Ciencias Agrícolas (INCA, en el verano del 2001, con el objetivo de comparar seis distancias de plantación en el cultivo de la Jamaica ( Hibiscus sabdariffa L. y su influencia en los rendimientos y sus componentes por superficie para definir la densidad óptima. Las distancias empleadas fueron: 1.20x1.00m; 1.20x0.90m; 1.00x1.00m; 1.00x0.90m; 0.90x0.90m y 0.90x0.80m; a esos marcos de plantación correspondieron las siguientes densidades: 8 333, 9 260, 10 000, 11 111, 12 345 y 13 888 plantas.ha -1 . Se utilizó un diseño de bloques al azar con cuatro repeticiones. Se evaluaron el peso de frutos más el cáliz fresco y seco por separado. Los datos se procesaron mediante un Análisis de Varianza de Clasificación Simple, encontrándose di- ferencias significativas entre los tratamientos. Los resultados mostraron que los rendimientos se comportaron en correspon- dencia con las densidades de plantación, obteniéndose 7.53 t.ha -1 de cálices frescos en la mayor densidad y 4.5 t.ha -1 en la menor.

  18. Densidad poblacional del venado cola blanca (Odocoileus virginianus en sabana inindable de Paz De Ariporo (Casanare, Orinoquia colombiana

    Directory of Open Access Journals (Sweden)

    Montenegro Olga Lucía

    2006-12-01

    Full Text Available Esta investigación buscó estimar y analizar las diferencias en la densidad poblacional del venado cola blanca
    (Odocoileus virginianus en dos hatos de la Orinoquia colombiana, con miras a aportar elementos para su manejo
    sostenible en la región. Para la estimación de densidad se realizaron conteos de individuos y grupos en transectos
    lineales de ancho variable acumulando 54,3 km y 48,65 km en los hatos Taparas y Miramar respectivamente.
    Estos recorridos se realizaron entre junio y julio de 2005, que corresponde a la época de lluvias. La densidad tanto
    de individuos como de grupos de venados fue mayor en el hato Taparas (0,44 venados/ha y 0,148 grupos/ha
    respectivamente que en el hato Miramar (0,11 venados/ha y 0,086 grupos/ha respectivamente. El número de hembras observadas fue mayor que el número de machos tanto en el hato Taparas (c2=165,8, p <0,05 como en el hato Miramar (c2=18, p <0,05. En los dos hatos la distribución de edades se caracterizó por una mayor proporción de adultos seguido por juveniles y crías. En el hato Taparas el tamaño promedio de grupo fue de 3,01, mientras en el hato Miramar éste fue de 1,55 individuos. Se discuten las diferencias en densidad en los dos hatos a la luz de presiones de cacería, variaciones en el hábitat e interacciones con el ganado vacuno de la zona.

  19. Medida de densidades con el picnómetro y de tensión superficial con el estalagmómetro

    OpenAIRE

    Espinosa Tomás, Julián; Pérez Rodríguez, Jorge; Miret Marí, Juan José; Caballero Caballero, María Teresa

    2010-01-01

    Guión de la práctica de Física de primero de grado de Óptica y Optometría "MEDIDA DE DENSIDADES CON EL PICNÓMETRO Y DE TENSIÓN SUPERFICIAL CON EL ESTALAGMÓMETRO" Objetivos: Medir densidades de sólidos y líquidos. Medir la tensión superficial de un líquido problema con el estalagmómetro.

  20. Optimization of Injection Molding Parameters for HDPE/TiO2 Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

    Directory of Open Access Journals (Sweden)

    Hifsa Pervez

    2016-08-01

    Full Text Available The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO2 nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO2, barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L9 orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO2, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA has also been applied to identify the most significant factor, and the percentage of TiO2 nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO2 nanocomposites fabricated through the injection molding process.

  1. Resistance of different materials used in sewers systems:Polyvinyl chloride (PVC, polypropylene (PP and High density polyethylene (HDPE, to sulfuric acid and sodium sulfate attack.

    Directory of Open Access Journals (Sweden)

    LASFAR Sara

    2014-02-01

    Full Text Available The behaviour of PVC, PP and HDPE used in sewer systems exposed to acid and sulfate solutions was investigated at 25°C and 40°C. Gravimetric characterization proves that PVC has a fickian behavior. It shows also, that PP has a non-fickian behavior, characterized by a rapid acceleration of water absorption, and the HDPE has a fickian behavior at 25°C, while it has a non-fickian behavior at 40°C, characterized by a weight loss after a certain aging period. The prolongation of the time of exposure to sulfuric acid solution leads to a progressive increase in tensile strength followed by a slight decrease at 40°C. The unaged samples of all materials have a much lower tensile strength than those of the aged samples, and a drop in elongation at break could be observed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density due to the diffusion of the solvent and the effect of the temperature as the exposure time increases. These results prove that there is a correlation between the diffusion of the solvent as well as the increased exposure time and temperature on the mechanical properties of polymer.

  2. Effects of Rice Husk Modification with Liquid Natural Rubber and Exposure to Electron Beam Radiation on the Mechanical Properties of NR/ HDPE/ Rice Husk Composites

    International Nuclear Information System (INIS)

    Rice husk (RH) powder is a natural fibre capable of reinforcing natural rubber thermoplastic (TPNR) NR/ HDPE composites on specific modification of the particle surface. In this study the modification of RH powder involved pre-treatment with 5 % sodium hydroxide (NaOH) solution, soaking in LNR solution and exposure of LNR coated RH to electron beam (EB) irradiation. Preparation of NR/ HDPE/ RH composites was via melt-mixing in an internal mixer at predetermined conditions. Morphology study of the composites using scanning electron microscope (SEM) showed a homogeneous distribution of modified RH particles and particle-matrix interaction in the composite. Modified RH filled composites exhibited a significant change in mechanical properties. The maximum stress and impact strength were 6.7 MPa and 13.2 kJ/ m2, respectively at 20 kGy radiation, while the tensile modulus was 79 MPa at 30 kGy dose. The interfacial RH-TPNR interaction for the LNR-EB treated RH particles had improved in the EB dosage range of 20-30 kGy. However, over exposure to radiation caused degradation of rubber coat and interaction between particles to increase. Agglomeration of filler particles would occur and caused inhomogeneous distribution of filler in the composite. (author)

  3. Aclimatação de mudas de acariquara à alta irradiância Acclimation of manwood seedlings to full sunlight

    Directory of Open Access Journals (Sweden)

    Nilvanda dos Santos Magalhães

    2009-07-01

    Full Text Available O objetivo deste trabalho foi determinar as mudanças fisiológicas que ocorrem em acariquara (Minquartia guianensis durante o processo de aclimatação à alta irradiância, bem como a estratégia de aclimatação dessa espécie. Plantas mantidas em baixa irradiância foram transferidas para alta irradiância por 290 dias. Durante esse período, foi medida a relação entre fluorescência variável e máxima (Fv/Fm, em folhas desenvolvidas à sombra e, após a senescência prematura por foto-oxidação, em folhas aclimatadas ao sol. Ao final do experimento, foram determinadas as características fotossintéticas e anatômicas da folha. A exposição à alta irradiância causou, logo após a transferência, forte fotoinibição e foto-oxidação parcial da folhagem, mas não provocou a morte da planta. Folhas produzidas no ambiente ensolarado apresentaram valores de Fv/Fm similares aos do controle. A fotossíntese saturada por luz e a fotossíntese saturada por CO2 foram 90 e 50% maiores em plantas aclimatadas à alta irradiância. A velocidade máxima de carboxilação da rubisco e a taxa máxima de regeneração da ribulose bisfosfato seguiram a mesma tendência. Folhas produzidas ao sol apresentaram maior densidade estomática e maior espessura foliar. A produção de folhas novas é a principal estratégia de aclimatação da acariquara à alta irradiância.The aim of this work was to determine the physiological changes that occur in manwood (Minquartia guianensis during the acclimation process to high irradiance, and also to determine the acclimation strategy of this species. Plants kept in low light were transferred to high irradiance for 290 days. During this period the ratio between variable fluorescence and maximum fluorescence (Fv/Fm was measured in leaves developed in the shade, and after premature senescence due to photooxidation, in sun-acclimated leaves. At the end of the experimental period the anatomic and photosynthetic

  4. Material management providing best value to TransAlta Utilities

    International Nuclear Information System (INIS)

    Materials management functions at TransAlta Utilities were outlined in several overhead viewgraphs. The system includes purchasing, contracts, fleet management, inventory control and warehouses management. Various components of the system are depicted, including: (1) integrated information system, (2) materials management (MM) process flow, (3) key suppliers, (4) commodity categories, (5) performance evaluation process, (6) new ways of working with service suppliers, (7) location of staff in the field and head office, (8) contracts, (9) tracking key performance indicators, (10) blocked invoice performance, and (11) warehouse optimization and inventory control. Current initiatives are being reviewed with a view to reduce operations to a single service centre, based on the corporate objective to increase the value of MM by 20 per cent by the year 2000. 3 tabs., 4 figs

  5. MICROTOMOGRAFIA DE ALTA RESOLUÇÃO NO SETOR MINERAL

    OpenAIRE

    Daniel Uliana; Henrique Kahn; Renato Contessotto; Juliana Livi Antoniassi

    2014-01-01

    A técnica de microscopia por tomografia de raios X (MRX) oferece uma capacidade única para análise de associações, morfologia e liberação de múltiplas fases através da aquisição direta de imagens tridimensionais de alta resolução. Trata-se de uma técnica de análise 3D não invasiva atualmente utilizada no setor mineral para caracterização de carvão, minerais industriais e de base, além de metais preciosos, complementando técnicas de microscopia já existentes como MLA e QEMSCAN. A técnica já é ...

  6. Chemical characterization earthenware on the Alta California Frontier

    International Nuclear Information System (INIS)

    Throughout what was Alta California archaeological have found in Spanish and Mexican Period missions, presides, pueblos, and ranchos fragments of hand-modeled and wheel-thrown, unglazed, low fired earthenware's. the extraordinary visual similarities between earthenware's found hundreds of miles apart has been explained by some as the most of the ceramics were produced and used locally. The research presented in this paper is based on the use of neutron activation analysis to compositionally characterize the paste of a sample of these earthenware's. Samples from the missions sites of Dolores, Santa Clara, San Jose, Santa Cruz, San Antonio and San Juan Capistrano and the presiders of san Francisco, Monterey, and San Diego have been analyzed

  7. Nano-CaCO3/HDPE复合材料流变性能的研究%Study on Rheological Behavior of Nano-CaCO3/HDPE Composites

    Institute of Scientific and Technical Information of China (English)

    常杰云; 张帆

    2012-01-01

    通过熔融共混法制备了纳米碳酸钙/高密度聚乙烯( nano-CaCO3/HDPE)复合材料,使用旋转流变仪研究了复合材料的动态流变性能.结果表明,当nano-CaCO3加入量≤4%(质量分数)时,随着nano-CaCO3含量的增加,nano-CaCO3/HDPE复合材料的储能模量、损耗模量和复数黏度均高于纯HDPE,并逐渐上升.%By the method of melt blending, HDPE/nano-CaCO3composites were prepared and the dy-namic rheological properties were studied by rotational rheometer. The results indicated after nano-CaCO 3 was treated with silane coupling agent, with the increasing content ( ≤4% ) of namo-CaCO3, the storage modu-lus , loss modulus and complex viscosity were rising with the nano-CaCO3 content, and higher than that of pure HDPE.

  8. Analytical protocol to study the food safety of (multiple-)recycled high-density polyethylene (HDPE) and polypropylene (PP) crates: Influence of recycling on the migration and formation of degradation products

    NARCIS (Netherlands)

    Coulier, L.; Orbons, H.G.M.; Rijk, R.

    2007-01-01

    An analytical protocol was set up and successfully applied to study the food safety of recycled HDPE and PP crates. A worst-case scenario was applied that focused not only on overall migration and specific migration of accepted starting materials but also on migratable degradation products of polyme

  9. Densidades de plantio na produtividade e qualidade de frutos de melancia

    Directory of Open Access Journals (Sweden)

    Anamaria RP Ramos

    2009-12-01

    Full Text Available O experimento foi conduzido na Embrapa Semi-Árido em Petrolina-PE, de setembro a dezembro de 2007, para avaliar o desempenho agronômico e a qualidade dos frutos de melancia cultivadas sob diferentes densidades de plantio. Foram avaliados três espaçamentos combinados com seis cultivares de melancia, sendo duas diplóides de polpa amarela (BRS Soleil e BRS Kuarah, duas triplóides (Híbrido Triplóide CPATSA e Extasy Seedless e duas cultivares comerciais, também diploídes e de fruto pequeno (Smile e Sugar Baby. O delineamento experimental utilizado foi em blocos ao acaso, com esquema fatorial em três repetições. Os tratamentos resultaram da combinação de três espaçamentos (2,0 x 0,3 m; 2,0 x 0,4 m e 2,0 x 0,5 m e seis cultivares de melancia. Foram realizadas duas colheitas, para o Hibrido Triplóide CPATSA e Extasy Seedless, aos 68 DAP (dias após o plantio e 82 DAP. O primeiro e o segundo "corte", respectivamente, para as outras cultivares aconteceram aos 63 DAP e 77 DAP. Avaliaram-se a massa fresca da parte aérea (g, massa média de frutos (g, produção comercial e refugo (g,; diâmetro do fruto (cm, comprimento do fruto (cm, espessura de casca (cm, teor de sólidos solúveis (SS, acidez titulável (AT, relação SS/AT e firmeza da polpa. As análises de variância foram realizadas usando-se o teste F e as médias comparadas através do teste de Tukey ao nível de 5% de probabilidade. De modo geral, os espaçamentos não afetaram a qualidade dos frutos, de modo que o aumento da densidade de plantas permitiu a obtenção de maior produtividade.The experiment was carried out in Petrolina, Pernambuco State, Brazil, from September to December 2007, to evaluate the agronomic performance and fruit quality of watermelon cultivated under different planting densities. Three planting spaces and six cultivars were evaluated, where two cultivars were of yellow pulp (BRS Soleil and BRS Kuarah, two cultivars were triploid (Triploid Hybrid

  10. PTC Effect of Graphene Nanoplatelets/PP/HDPE Composite%石墨烯微片聚丙烯/高密度聚乙烯的复合材料的正温效应

    Institute of Scientific and Technical Information of China (English)

    吴福荣; 洪江彬; 李健鹏; 陈国华

    2012-01-01

    In this paper, the KNG-150 graphene nanoplatelets (GNPs) was used as the conductive filler, and the polypropylene (PP) /high density polyethylene (HDPE) composite system were used as the matrix material, produced the GNPs/PP/HDPE conductive composite, the effect of the GNPs contents and the proportion of PP/HDPE on the intensity PTC and NTC are invented. The result showed that the intensity PTC of this composite reach the max when the content of the GNPs was 6% j The PTC intensity efficiently enhanced and the NTC intensity was inhibited as the PP was added into the composite. When the proportion of m(PP) ! m(HDPE) was 3 ! 7, this composite reached the best result, the PTC and NTC intensity was 5. 58 and 0. 25.%以KNG-150石墨烯微片(GNPs)为导电填料,PP(聚丙烯)/HDPE(高密度聚乙烯)复合体系为基体材料,制备石墨烯微片/PP/HDPE导电复合材料,研究GNPs质量分数,PP/HDPE质量比对材料的正温度系数效应(PTC)强度和负温度系数效应(NTC)强度的影响.结果表明:GNPs质量分数处在渗滤区间6%时,材料的PTC强度达到最大值;PP的加入可以有效地提高材料的PTC强度,同时还抑制了NTC效应;当PP/HDPE质量比为3∶7时,效果最佳,此时PTC强度为5.58,NTC强度仅为0.25.

  11. TransAlta Corporation 1996 annual report : new directions, new opportunities

    International Nuclear Information System (INIS)

    TransAlta Corp. is an energy management company that operates through two subsidiaries: (1) TransAlta Utilities Corp. which owns and operates electricity generation, transmission and distribution assets in Alberta, and (2) TransAlta Energy Corp. which is in the business of electric and thermal energy supply, gas and electricity distribution, energy services and energy marketing in regions of Canada, New Zealand, Australia, Argentina and the United States. This report presents a summary of operations, and provides consolidated financial statements and common share information for 1996. During the year the corporation advanced three significant initiatives (1) operational effectiveness, as shown by impressive productivity increases, and major investments in three independent power projects, (2) improved strategic direction through a review of plans and options, resulting in a clearer, more focused vision of the future, and (3) realignment of the organizational structure by centralizing marketing and sales functions, and establishing a corporate business development group. Details of operational and financial results were provided for both subsidiaries, i. e. TransAlta Utilities and TransAlta Energy. Sales of electric energy for TransAlta Utilities amounted to 27.8 billion kWh; 4.6 billion kWh for TransAlta Energy. Return on equity was 11.4 per cent, down from 11.8 per cent in 1995. Net earnings per common share were $1.14 per share (including one-time items), the same as in 1995. tabs., figs

  12. Impact of Nursery Seeding Density, Nitrogen, and Seedling Age on Yield and Yield Attributes of Fine Rice Impacto de la Densidad de Siembra en Vivero, Nitrógeno, y Edad de Plántula sobre Rendimiento y Atributos de Rendimiento de Arroz Fino

    Directory of Open Access Journals (Sweden)

    Naeem Sarwar

    2011-09-01

    diferentes densidades de siembra (alta y baja y condiciones de N (con y sin en el cultivo del arroz temporadas 2008 y 2009. Independiente de la densidad de siembra y la aplicación de fertilizantes, plántulas de vivero de 10-d presentaron mayores rendimientos y componentes de rendimiento (tallos productivos, altura de planta, peso de 1000 granos, y rendimiento de paja, mientras que en etapas posteriores se observó una interacción significativa con el manejo de vivero. El trasplante de plántulas fértiles de 20 d cultivadas con baja densidad de siembra en la cama del vivero, se tradujo en un mayor número de macollos productivos m-2 (233,3; 227,3, producción de paja (11,1; 10,7 t ha-1, y rendimiento final (3,6; 3,4 t ha-1, en los años 2008 y 2009 respectivamente. Los atributos de rendimiento y el rendimiento se redujeron significativamente después del trasplante plántulas mayores cultivadas con alta densidad de siembra y sin fertilizante en vivero. Producción de macollos (165,7; 133, rendimiento de paja (8,7; 8,1 t ha-1 y rendimiento de arroz (2,0; 1,8 t ha-1 mínimos se registraron con trasplante de plántulas mayores de 40 d cultivadas con alta de densidad de siembra y sin aplicación de N. Estos hallazgos sustentan el uso de plántulas jóvenes en un sistema de intensificación de arroz e ilustran que con una pequeña inversión adicional en el cultivo de plántulas sanas y vigorosas en la cama de semillas del vivero, los agricultores pueden aumentar los rendimientos.

  13. Three-dimensional observation of the phase structure of high density polyethylene (HDPE)/poly(ethylene-co-butene) (PEB) blend by laser scanning confocal microscopy

    Institute of Scientific and Technical Information of China (English)

    ZHANG ChengGui; DONG Xia; WANG DuJin; HAN Charles C

    2007-01-01

    In this paper, high density polyethylene (HDPE)/poly(ethylene-co-butene) (PEB) blend (50/50 wt%) was prepared through solution blending and then compression molding, and subsequently examined by laser scanning confocal microscopy (LSCM). The PEB used in this experiment was labeled with a small quantity of a fluorescein derivative to render fluorescence. The initial films showed uniform dye distribution and no indication of phase separation within the resolution of optical microscopy. Sample films annealing at 140℃ followed by rapid cooling to room temperature showed obvious phase separation and bicontinuous structure. The present work indicates that by labeling one component with fluorescein derivative, LSCM can efficiently perform in situ depth profiling of polymer blends.

  14. Effect of Extractant and Cold-drawing on the Structure and Performance of HDPE Hollow Fiber Membranes Fabricated via Thermally Induced Phase Separation Method

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-li; RUAN Wen-xiang; SONG Yi-lin; JI Jian-bing; YAO Ke-jian

    2006-01-01

    Microporous polyolefin hollow fiber membranes were prepared from high density polyethylene (HDPE)-paraffin solution via thermally induced phase separation (TIPS)method. Effects of extraction and cold-drawing condition on membrane structure and performance were investigated.Five volatile solvents were used as extractant. Dimension of hollow fiber and gas permeation rate of membrane were measured. Microstructure of membrane was examined by Scanning Electronic Microscope (SEM). The results show that the membrane treated by pentane possesses a higher porosity, nitrogen permeability and lower shrinkage than those of membranes extracted by other three extractants. It is also found that thc membrane stretched 133% shows the highest porosity and gas permeability in this study.

  15. Basic density and pulp yield relationship with some chemical parameters in eucalyptus trees Densidade e rendimento em polpa celulósica e sua relação com alguns parâmetros químicos no eucalipto

    Directory of Open Access Journals (Sweden)

    Ana Maria Loureiro da Seca

    2006-12-01

    /guaiacilo (S/G e seringaldeído/vanilina (S/V. As amostras dos quartis de alta densidade e as de baixo rendimento foram semelhantes, ambas com baixos valores de S/V (3,99-4,09 e S/G (3,88-4,12 e os mais elevados teores de fenóis totais (13,3-14,3 g de ácido gálico por quilograma. As madeiras do quarto quartil de rendimento são estatisticamente distintas das outras, com as maiores razões S/G (5,15 e S/V (4,98 e os menores teores de fenóis totais (8,7 g de ácido gálico por quilograma. Os parâmetros grupos metoxílicos e açúcares totais são os mais adequados para a diferenciação das amostras provenientes do primeiro quartil de densidade.

  16. Sistema de monitorización continua de descargas parciales para trasformadores de alta potencia

    OpenAIRE

    Lastra Rodríguez, Daniel

    2012-01-01

    La monitorización de transformadores de alta potencia se presenta como una tarea crucial dentro del mantenimiento de las subestaciones eléctricas. Además de pérdidas de suministro, los fallos en los transformadores de alta potencia llevan asociados una serie de costes que en ocasiones pueden llegar a dispararse. Mientras se encuentra en servicio, un transformador de alta potencia proporciona gran variedad de información entre la que podemos destacar la facilitada por las descargas parciales p...

  17. Hemorragia digestiva alta em idosos e não idosos

    OpenAIRE

    Pereira, Tiago José Felizardo

    2012-01-01

    A Hemorragia Digestiva Alta tem vindo apresentar um crescimento significativo em idosos, contribuindo com 35 a 45% dos casos de Hemorragia Digestiva Alta. Foi realizado um estudo descritivo, observacional e transversal, com o objetivo de identificar quais as características epidemiológicas das Hemorragias Digestivas Altas em idosos e não idosos admitidos na Unidade de Endoscopia Digestiva do Centro Hospitalar Cova da Beira, na Região da Cova da Beira – Portugal, no período de 1...

  18. Estudio de capas delgadas de dieléctricos de alta permitividad depositadas por ALD

    OpenAIRE

    Fuentes Díaz, Lissa María

    2014-01-01

    El impulso acelerado de la industria microelectrónica ha conducido al empleo de dieléctricos de alta permitividad (K) como una alternativa para continuar el escalado. Tanto en aplicaciones espaciales, médicas, como de física de alta energía los transistores son sometidos a ambientes de fuertes irradiaciones provocando una degradación progresiva de los dispositivos. La respuesta de la fiabilidad de los dieléctricos de alta K frente la irradiación determinará su viabilidad e inco...

  19. Altas Capacidades en Educación Infantil en Guipúzcoa

    OpenAIRE

    Omaetxebarria-Aldarono, Ainara

    2013-01-01

    El trabajo fin de grado que se presenta a continuación aporta información acerca de las altas capacidades en Educación Infantil y su relación con las inteligencias múltiples. Se propone una perspectiva de la realidad actual del tema en el contexto de la provincia de Guipúzcoa. Las altas capacidades se proponen aludiendo a varios aspectos, entre ellos, se define el término, se aportan características de los alumnos con altas capacidades, se señalan alternativas de intervención en las aulas y s...

  20. Altas capacidades intelectuales. Diagnóstico y seguimiento de una NEE.

    OpenAIRE

    Pérez-i-Martra, Pep

    2013-01-01

    Según la OMS, el 2,3% de la población mundial tiene altas capacidades intelectuales, es decir, en la vida académica de un profesor, éste tendría que descubrir una media de 40 alumnos con capacidades superiores a la media. Saber en qué consisten las altas capacidades y hacer un pre diagnóstico de las mismas será, en muchas ocasiones, trabajo del profesor de secundaria. Pero, ¿tiene éste conocimientos para percatarse de la presencia en clase de un alumno con altas capacidades? ¿Y una vez estudi...

  1. El alumnado con altas capacidades intelectuales: programas de intervención.

    OpenAIRE

    González Arranz, Raquel

    2015-01-01

    El presente Trabajo de Fin de Grado se centra en alumnos considerados de Educación Especial, concretamente en aquellos que poseen Altas Capacidades Intelectuales y las posibilidades de respuesta educativa que se les puede ofrecer dentro del modelo de aula ordinaria. En la primera parte, se afronta el estudio de alumnos con altas capacidades intelectuales en educación primaria. Los temas que se tratan son: conceptualización y definiciones, fundamentación teórica de alumnos con altas capaci...

  2. Espondiloartritis y su relación con las fracturas vertebrales y la densidad mineral ósea

    OpenAIRE

    Sánchez González, María Dolores

    2016-01-01

    [ES] En el presente trabajo se estudia la espondilitis anquilosante (EA), enfermedad inflamatoria crónica más común en varones, y la relación de la misma con las fracturas vertebrales y la densidad mineral ósea, debido a que en los varonos como resultado de una respuesta inmune, se produce una inflamación en las articulaciones sacroiliacas, vertebrales y otras adyacentes. Es frecuente que los pacientes también tengan inflamación en las entesis (inserción del tendón o del ligamento en el hues...

  3. Biomasa y densidad de dos especies de pastos marinos en el sur de Quintana Roo, México

    OpenAIRE

    Martha Angélica Gutiérrez-Aguirre; María Gabriela de la Fuente-Betancourt; Adrián Cervantes-Martínez

    2000-01-01

    La biomasa y productividad de una comunidad de pastos marinos es útil para determinar el estado ecológico de la costa. Se comparó la biomasa foliar y la densidad de vainas en praderas de Thalassia testudinum Banks & Sol. ex K. D. Koenig, en dos ambientes de la costa del Caribe mexicano (N= 6 cuadrantes/sitio) en Noviembre de 1998. Los valores de vainas y biomasa foliar fueron más bajos en la pradera asociada al manglar, que en la pradera establecida en una laguna arrecifal. Esto probablemente...

  4. Densidad ósea y frecuencias de restos humanos en Tierra del Fuego. Análisis exploratorio

    OpenAIRE

    Suby, Jorge A.; Guichón, Ricardo Aníbal

    2003-01-01

    La disponibilidad del registro biológico humano para su estudio esta condicionada por procesos paleoecológicos y tafonómicos. Cuales probablemente van a ser los especimenes mejor y peor representados constituye un dato importante al momento de decidir que preguntar. En relación con esta problemática nos interesa explorar la relación entre la densidad mineral ósea y las frecuencias relativas con que se presenta el registro biológico humano en varias colecciones del norte de Tierra del Fuego. L...

  5. Densidad del Mono aullador Alouatta seniculus (Linnaeus, 1766) Mammalia: primates en el arroyo coloso, Departamento de Sucre, Colombia

    OpenAIRE

    Fajardo Patiño Alirio; De la Ossa Velasquez Jaime L.

    1996-01-01

    Nueve manadas de Alouatta seniculus, fueron estudiadas a lo largo de tres meses y medio, entre Mayo y Agosto de 1983. Se tomaron en cuenta aspectos relativos al estado y densidad poblacional en el Arroyo Colosó, Departamento de Sucre. Se establece una relación de los datos obtenidos y procesados en este trabajo con los suministrados por otros autores en estudios similares con la misma especie y en diferentes lugares.Nine troops of Alouatta seniculus, were studied for a period of three and hal...

  6. Densidad y biomasa de Pterois volitans/miles (Teleostei: Scorpaenidae) en arrecifes del litoral oeste de La Habana, Cuba

    OpenAIRE

    García-Rodríguez, Alain; Chevalier Monteagudo, Pedro P.; Cabrera Sansón, Erlán; Caballero Aragón, Hansel; Luis Hernández López, Jorge

    2015-01-01

    El pez león (Pterois volitans/miles) es la primera especie (s) de pez arrecifal del Indo- Pacífico que invade el Atl{ntico Occidental, constituyendo una de las invasiones de peces marinos m{s r{pida de la historia. El objetivo fue determinar la densidad y biomasa de las poblaciones del pez león y sus posibles variaciones temporales y espaciales en arrecifes del oeste de La Habana, Cuba. Los muestreos fueron realizados mediante censos visuales con buceo autónomo en los períodos ...

  7. Densidade de semeadura de duas espécies de ervilhaca sobre caracteres agronômicos e composição bromatológica

    Directory of Open Access Journals (Sweden)

    Sidney Ortiz

    2015-02-01

    Full Text Available O estande de plantas é um dos principais componentes do rendimento que altera a produtividade das culturas, maximizando o ambiente produtivo para a cultura. Nesse sentido, objetivou-se com este trabalho avaliar a produção de forragem e a composição química de duas espécies de ervilhaca em diferentes densidades de semeadura. O experimento foi conduzido no ano de 2011, em área experimental do Departamento de Fitotecnia da Universidade Federal de Santa Maria, Rio Grande do Sul. Os tratamentos constaram de duas espécies de ervilhaca (ervilhaca peluda e ervilhaca comum em quatro densidades de semeadura (50, 100, 150 e 200 sementes m-2. O delineamento experimental utilizado foi o de blocos ao caso, disposto em fatorial (2x4, em quatro repetições. Os valores de FDA aumentaram conforme o aumento da densidade de semeadura, o que não ocorreu para as demais características bromatológicas avaliadas. A densidade ótima de semeadura deve ser ajustada conforme a espécie e o corte, variando de 66 a 200 sementes viáveis por metro quadrado. A produção de massa seca total é maximizada quando a densidade de semeadura for de 136 sementes viáveis m-2

  8. Monitorización del estrés hídrico en un olivar en seto de alta densidad con sondas de presión de turgencia en hojas

    OpenAIRE

    Rodríguez Domínguez, Celia M.

    2011-01-01

    70 páginas.-- 15 figuras.-- 1 tabla.-- 71 referencias.-- Curso 2010-2011. Trabajo de iniciación a la investigación. Memoria para optar al Diploma de Estudios Avanzados por la Universidad de Sevilla. Línea de investigación "Efecto medioambiental de los fertilizantes y el riego en la agricultura"

  9. Dosimetry characterization and clinical application of Exa skin: Bolus of high of high density for use with photons; Caracterizacion dosimetrica y aplicacion clinica de Exaskin: bolus de alta densidad para uso con fotones

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz Seidel, M.; Velazquez Miranda, S.

    2013-07-01

    Bolus of high density eXaSkin of density 1.6 g/cm{sub 3} is calculated correctly in the planning systems, is easy to use and generates optimum coupling with the radiation area, at the same time which is easily reproducible in their placement, avoiding the use of electron beams. On the other hand its behavior varies very slightly with the presence of air gaps. (Author)

  10. Higher glandular trichome density in tomato leaflets and repellence to spider mites Alta densidade de tricomas glandulares em tomateiro e aumento da repelência a ácaros rajados

    OpenAIRE

    Wilson Roberto Maluf; Irene Fumi Inoue; Raphael de Paula Duarte Ferreira; Luiz Antonio Augusto Gomes; Evaristo Mauro Castro; Maria das Graças Cardoso

    2007-01-01

    The objective of this work was to evaluate the feasibility of selection for higher glandular trichome densities, as an indirect criterion of selection for increasing repellence to spider mites Tetranychus urticae, in tomato populations derived from an interspecific cross between Lycopersicon esculentum x L. hirsutum var. glabratum PI 134417. Trichome densities were evaluated in 19 genotypes, including 12 from advanced backcross populations, derived from the original cross L. esculentum x L. h...

  11. Transporte de juvenis de curimbatá Prochilodus lineatus em diferentes densidades - doi: 10.4025/actascianimsci.v32i2.8415 Transportation of curimbata Prochilodus lineatus juveniles in different densities - doi: 10.4025/actascianimsci.v32i2.8415

    Directory of Open Access Journals (Sweden)

    João Batista Kochenborger Fernandes

    2010-07-01

    Full Text Available Neste estudo foi avaliado o efeito do transporte de curimbatá Prochilodus lineatus, em três densidades (100, 150 e 250 g L-1, sobre a sobrevivência e variáveis metabólicas, iônicas e hematológicas (série vermelha. Juvenis de curimbatá foram transportados em sacos plásticos durante 6h e amostrados antes da embalagem, imediatamente após a chegada, 24 e 96h após o transporte. Os peixes transportados na densidade mais alta apresentaram maior mortalidade durante o período de recuperação. As variáveis físico-químicas da água: condutividade e amônia total apresentaram maiores valores quanto maior a densidade (p -1 induziu maior mortalidade e os piores valores nas variáveis avaliadas. O período de 96h de recuperação após evento estressante foi suficiente para o retorno aos valores basais das variáveis hematológicas, mas não foi suficiente para as metabólicas e iônicas. aThis study evaluated the effects of curimbata Prochilodus lineatus transportation in three densities (100, 150 and 250 g L-1 on survival, metabolic, ionic and hematological (red series variables. Curimbata juveniles were transported in plastic bag during six hours, and sampled before packing, immediately after the arrival, 24 and 96 hours after transportation. During recovery, higher mortality was seen in fish transported in the highest density. Water variables, such as conductivity and total ammonia, presented increased values as density increased (p -1 density induced the highest mortality rate and the worst variables values measured. 96 hours of recovery after the stressing event was enough to return to initial values for hematological variables, but was not sufficient to return to initial values for metabolic and ionic variables.

  12. Neuromielitis óptica con alta expresión de acuaporina-4 y anticuerpos anti-acuaporina-4 positivos en suero

    Directory of Open Access Journals (Sweden)

    Alejandra Báez

    2012-04-01

    Full Text Available La presencia de anticuerpos IgG en suero, con blanco en los canales de acuaporina-4, es específica de la neuromielitis óptica (NMO. El 60% de los pacientes con NMO presentan lesiones cerebrales en la resonancia magnética (RM; en un 8% (mayoría niños estas lesiones se consideraron "atípicas". Presentamos dos pacientes con NMO y lesiones en el SNC de alta expresión de acuaporina-4. Caso 1: varón de 50 años, que comenzó con pérdida de visión en ojo derecho (OD. Recibió tratamiento empírico con metilprednisolona 1 g/d x 3 días. Al mes presentó dolor generalizado y hemiparesia derecha; nuevamente recibió metilprednisolona 1 g/d x 5 días e IgG IV 400 mg/kg/d × 5 días. Recuperó la deambulación persistiendo el dolor y fenómenos paroxísticos en los 4 miembros. Potenciales evocados visuales: P100, ojo izquierdo (OI 123 mseg. OD sin respuesta. La RM de cerebro (FLAIR mostró hiperintensidad en nervio óptico derecho, hipotálamo y comisura blanca anterior. RM cervical: lesión medular extensa (5 cuerpos vertebrales. Caso 2: mujer de 53 años, con disminución de la agudeza visual en ambos ojos y parestesias en miembros inferiores que remitieron espontáneamente. Evolucionó al mes con cuadriparesia e incontinencia esfinteriana. Recibió metilprednisolona 1 g/d x 5 días, sin mejoría. Potenciales evocados visuales: P100 OI 124 mseg. OD 128 mseg. RM cerebro: (FLAIR hiperintensidad hipotalámica y periacueductal. RM cervical: lesión medular extensa (7 cuerpos vertebrales. Anticuerpos anti-acuaporina-4 positivos en ambos pacientes (inmunofluorescencia indirecta. Las lesiones consideradas "atípicas", como aquí, en sitios con alta densidad de proteínas canales de agua AQP4 deberán considerarse para el diagnóstico diferencial.

  13. Caracterización morfométrica de la cuenca alta del arroyo Las Lajas, Córdoba: Un análisis estadístico

    Directory of Open Access Journals (Sweden)

    N. Doffo

    2005-03-01

    Full Text Available En base a un análisis estadístico de los principales parámetros morfomé tricos, se hace una caracterización hidrológica de la cuenca alta del arroyo Las Lajas. En particular se discute la influencia de la estructura y litología sobre el diseño de la red de drenaje. La cuenca alta del arroyo Las Lajas drena una superficie aproximada de 41 km² y se desarrolla sobre un basamento plutónico-metamórfico del Precámbrico-Paleozoico superior. El relieve está conformado por serranías bajas, valles de fondo plano, con relleno aluvial y coluvial. La precipitación media anual es de 860 mm. La forma de la cuenca está parcialmente controlada por la Falla Las Lajas. Los parámetros morfométricos utilizados son: densidad de drenaje, frecuencia de cursos de primer orden, rugosidad de la cuenca, relación de bifurcación, relación de longitudes y relación de elongación. Estos se aplicaron a subcuencas de tercer orden, agrupadas en un sector oriental y otro occidental, delimitados por la Falla Las Lajas. De cada parámetro medido se obtuvieron estadísticos de posición y de dispersión y se realizaron, previa prueba de normalidad y de correlación, tests estadísticos, análisis de agrupamiento y factorial. El resultado no demuestra que exista un control litológico sobre el diseño de la red de drenaje. Un análisis de agrupamiento sobre las subcuencas indica una división en dos conjuntos que no muestran una relación obvia con la estructura ni la litología del sustrato.

  14. Efeitos da atividade física na densidade mineral óssea e na remodelação do tecido ósseo Efectos de la actividad física en la densidad mineral ósea y en la remodelacion del tejido óseo Effects of the physical activity on the bone mineral density and bone remodelation

    Directory of Open Access Journals (Sweden)

    Eduardo Lusa Cadore

    2005-12-01

    Full Text Available Este artigo revisa os efeitos de diferentes modalidades esportivas e do treinamento de força na remodelação óssea e discutir as possíveis relações da densidade mineral óssea (DMO com a força muscular e a composição corporal. Numerosos estudos indicam que a atividade física de alto impacto, ou que exija alta produção de força, pode ter um efeito benéfico na DMO, devido à deformação desse tecido, ocorrida durante a atividade. Alguns autores têm avaliado os efeitos do treinamento físico em alguns marcadores bioquímicos da remodelação óssea, já que a variação das concentrações desses marcadores pode indicar um estado de formação ou reabsorção óssea. Entretanto, a inconsistência dos resultados encontrados sugere que a análise dos efeitos da atividade física na remodelação óssea, através desses marcadores, deve ser mais investigada. Existem muitas discrepâncias a respeito da relação entre a DMO com a força muscular e a composição corporal, principalmente na determinação de qual desses fatores está mais associado com a DMO. A determinação de qual o tipo de atividade física seja ideal para aumentar o pico de massa óssea na adolescência, ou mesmo mantê-la após a idade adulta, é muito importante para a prevenção e o possível tratamento da osteoporose.Este artículo busca revisar los efectos de modalidades deportivas diferentes y del entrenamiento de fuerza en la remodelación del hueso y discutir las posibles relaciones entre la densidad mineral del hueso (DMO con la fuerza muscular y la composición corporal. Los numerosos estudios indican que la actividad física de alto impacto o que exige producción alta de fuerza, pueden tener un efecto beneficioso en la DMO, debido a la deformación que ese tejido, pasa durante la actividad física. Algunos autores han estado evaluando los efectos de la educación física en algunos marcadores bioquímicos de la remodelación del hueso, desde la variaci

  15. Audiitor kaebas Alta Capitali arve pärast Läti kohtusse / Henrik Ilves

    Index Scriptorium Estoniae

    Ilves, Henrik

    2008-01-01

    Eesti Päevalehe andmetel kaebas rahvusvaheline audiitorfirma Ernst & Young Lätis kohtusse investeerimisfirma Alta Capital, kuna firma ei ole maksnud esitatud arvet. Nõude suuruseks on 4,69 miljonit krooni

  16. Il programma italiano di ricerche nella alta atmosfera

    Directory of Open Access Journals (Sweden)

    l. BROGLIO

    1962-06-01

    Full Text Available La Commissione per le Ricerche Spaziali, nominata dal ConsiglioNazionale delle Ricerche diciotto mesi fa, ha intrapreso un programmadi studio dell'alta atmosfera a mezzo di razzi sonda. Questa ricerca,che nella attuale prima fase di lavoro e sviluppo deve essere consideratauna delle attività basilari della Commissione, aveva ed ha un duplicescopo: uno scopo diretto, immediato, che consiste nell'acquisizione didati scientifici, in maggior copia possibile, tali da ampliare ed approfondirele attuali conoscenze sulla struttura e sulla dinamica della altaatmosfera.Il secondo scopo è, se così si può dire, proiettato nel futuro. L'organizzazionepredisposta, sia in uomini che in attrezzature ed installazioni,per questa ricerca può considerarsi infatti come il nocciolo di unapiù ampia organizzazione che potrà operare negli anni successivi permaggiori e più impegnativi compiti.I fondi necessari per lo sviluppo del programma di ricerche nell'altaatmosfera sono stati forniti alla Commissione delle Ricerche Spazialiin base ad un accordo fra il C.N.R. e il Comitato Razzi e Missili delMinistero della Difesa, secondo il quale i due Enti si impegnavano acontribuire alle spese necessarie su base paritetica.II C.N.R. stipulò anche un accordo di natura scientifica con l'Entespaziale statunitense N.A.S.A., sia per ottenere dalla Commissione delleRicerche Spaziali un appoggio tecnico, sia per altre finalità di cui siparlerà più diffusamente in seguito.

  17. Demografia e densidade de perfilhos de capim-braquiária sob pastejo em lotação intermitente

    Directory of Open Access Journals (Sweden)

    Jorge Nunes Portela

    2011-03-01

    Full Text Available O objetivo deste trabalho foi avaliar os efeitos de intensidades de pastejo e de frequências de desfolha na demografia e densidade de perfilhos de capim-braquiária (Urochloa decumbens syn. Brachiaria decumbens sob lotação intermitente. Foram avaliados duas intensidades de pastejo (5 e 10 cm de altura pós-pastejo e duas frequências de desfolha (período de descanso até que o dossel atingisse 95 e 100% de interceptação luminosa, IL, de agosto de 2007 a agosto de 2008. Utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial com quatro repetições. Avaliaram-se as densidades populacionais e as taxas de aparecimento e sobrevivência de perfilhos basais (DPPb, TAPb e TSPb, respectivamente e aéreos+basais (DPPab, TAPab e TSPab. As maiores TAPb e TAPab, no outono, foram obtidas nos pastos desfolhados a 10 cm. Porém, no final da primavera e no verão, a intensidade de 5 cm resultou em maiores taxas, que promoveram maior DPPb. No verão, a TSPb foi maior para pastos manejados à intensidade de 10 cm. O manejo da pastagem que resulta em maiores DPPab, TAPab e TSPab, durante as épocas de rápido crescimento dos pastos, é o de 10 cm de intensidade de pastejo e 95% de IL de frequência de desfolha.

  18. Efecto de la densidad de siembra y la adición de ácido ascórbico en el cultivo de Osteoglossum bicirrhosum

    Directory of Open Access Journals (Sweden)

    Carolina Cuaical T.

    2013-11-01

    Full Text Available Objetivo. Evaluar el efecto de la densidad de siembra y la adición de ácido ascórbico en la alimentación de alevinos de O. bicirrhosum, cultivados en jaulas. Materiales y métodos. Se incluyeron 396 alevinos y se distribuyeron en nueve tratamientos, resultado de la combinación de los niveles del factor densidad de siembra: 1pez/5 L; 1pez/10 L y 1pez/15 L y los niveles de ácido ascórbico: 0; 500 y 1000 mg/kg. Los datos obtenidos se evaluaron mediante el análisis de varianza del diseño factorial 32. Resultados. La densidad de siembra presentó diferencias estadísticas significativas en el incremento de peso. Las variables incremento de longitud y tasa de crecimiento específico no presentaron diferencias estadísticas. En cuanto a la conversión alimenticia aparente, se demostraron diferencias significativas en los dos factores: La densidad de 1pez/10 L indicó la mejor conversión con un valor de 1.50, asimismo, la inclusión de 1000 mg de ácido ascórbico por Kg de alimento mostró los mejores promedios con 1.55. En la sobrevivencia se precisaron diferencias estadísticas entre los tratamientos de la densidad de 1pez/5 L, siendo mejores aquellos que incluyeron ácido ascórbico en la dieta. Conclusiones. La densidad de 1pez/10 L registró el mayor incremento de peso con 31.83 g en 87 días. La sobrevivencia general fue del 96%, lo que demuestra la eficiencia del sistema de cultivo utilizado, al tiempo que actúa de manera positiva en el desarrollo de esta especie.

  19. Transmissividade a radiação solar do polietileno de baixa densidade utilizado em estufas Solar radiation transmissivity through low density polyethylene used in greenhouses

    OpenAIRE

    Galileo Adeli Buriol; Nereu Augusto Streck; Cláudia Petry; Flavio Miguel Schneider

    1995-01-01

    Determinou-se a transmissividade à radiação solar do polietileno de baixa densidade utilizado em estufas. O experimento foi conduzido em uma estufa tipo Capela com dimensões de 10m x 25m, coberta com polietileno transparente de baixa densidade, com espessura de 100µm e aditivado com anti-UV, instalada no Departamento de Fitotecnia da Universidade Federal de Santa Maria, RS - Brasil. A radiação solar global diária incidente no interior e exterior da estufa foi medida no período de julho de 199...

  20. Produção do milho híbrido 30F35HR cultivado na savana de Roraima em diferentes densidades de plantio.

    OpenAIRE

    Valle, Ítalo César Aguiar; Alves, José Maria Arcanjo; Silva, Luana dos Santos; Uchôa, Sandra Cátia Pereira; Albuquerque, José de Anchieta Alves de; Silva, Deyse Cristina Oliveira da

    2013-01-01

    A densidade de plantas pode maximizar o potencial produtivo de variedades de milho melhoradas, uma vez que, em geral, estas apresentam porte mais baixo e arquitetura foliar mais ereta. Objetivou-se com esse trabalho avaliar o efeito de três densidades de plantios nos componentes de produção do milho transgênico híbrido Pioneer 30F35HR cultivado na savana de Roraima. O experimento foi conduzido na área experimental do Centro de Ciências Agrárias da Universidade Federal de Roraima, no Campus do...

  1. Densidades de plantio e doses de biofertilizante na produção de capim-limão Density and biofertilizer levels for lemon grass production

    OpenAIRE

    Blank, Arie F.; Maria de Fátima Arrigoni-Blank; Verônica F Amancio; Marcelo da C Mendonça; Luiz G M de Santana Filho

    2007-01-01

    O objetivo do trabalho foi avaliar o efeito de densidades de plantio e doses de biofertilizante comercial na produção de capim-limão (Cymbopogon citratus (D.C.) Stapf). O experimento foi implantado em parcelas subdivididas com três repetições, colocando-se nas parcelas as densidades de plantio (33.333, 49.382, 55.555 e 111.111 plantas ha-1) e nas subparcelas as doses de biofertilizante (0; 20; 40 e 60 t ha-1). Foram realizadas nove colheitas em intervalos de 42 dias. Avaliou-se a sobrevivênci...

  2. Influencia de tres densidades de siembra y cuatro niveles de fertilización en la variedad de maíz INIA 612-Maselba

    OpenAIRE

    Walker Cubas Pérez; Christian Córdova Díaz

    2013-01-01

    El experimento se realizó el año 2008, en el Campo Experimental San Miguel de la EEA. San Roque del INIA - Loreto, con el objetivo de determinar el efecto de diferentes densidades de siembra y niveles de fertilización nitrogenada en el rendimiento de grano de la variedad de maíz amarillo duro, INIA 612 – MASELBA; en condiciones de suelos aluviales de restinga inundable. Se evaluaron tres densidades de siembra, 0,80m x 0,50m con 2 plantas por sitio (50 000 plantas/ha), 0,8m x 0,60m con 3 plant...

  3. MICROTOMOGRAFIA DE ALTA RESOLUÇÃO NO SETOR MINERAL

    Directory of Open Access Journals (Sweden)

    Daniel Uliana

    2014-07-01

    Full Text Available A técnica de microscopia por tomografia de raios X (MRX oferece uma capacidade única para análise de associações, morfologia e liberação de múltiplas fases através da aquisição direta de imagens tridimensionais de alta resolução. Trata-se de uma técnica de análise 3D não invasiva atualmente utilizada no setor mineral para caracterização de carvão, minerais industriais e de base, além de metais preciosos, complementando técnicas de microscopia já existentes como MLA e QEMSCAN. A técnica já é empregada há algum tempo na indústria do petróleo para a caracterização de tamanho e distribuição de poros, permitindo simular o fluxo de óleo em rochas reservatório. Além disso, a caracterização de poros em 3D permite a simulação de fluxo em processos de lixiviação. Requerendo pouca ou nenhuma preparação da amostra, comparativamente às técnicas de microscopia bi ou unidimensionais proporciona vantagens como a preparação muito mais ágil da amostra, aquisição direta de dados volumétricos, análise quantitativa em 3D e menor tempo de análise aliado a maior representatividade do material analisado. Particularmente em estudos de metais preciosos, tem-se um significativo aumento na probabilidade de detecção dos minerais de interesse. Recentes avanços com o emprego de dupla magnificação – projeção cônica aliada à utilização de lentes ópticas - possibilitam a aquisição de imagens com resolução submicrométrica com sensível melhoria no contraste entre as fases.

  4. Caracterização de ambientes com alta ocorrência natural de araticum (Annona crassiflora Mart. no Estado de Goiás Environmental characterization with high natural occurrence of araticum (Annona crassiflora Mart. in Goiás State

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Machado Mesquita

    2007-04-01

    Full Text Available Foram selecionadas 14 áreas no Estado de Goiás, Brasil, com alta densidade da espécie araticum (Annona crassiflora Mart. e com menor ação antrópica possível. Cada área possuía 1,0ha, estando subdividida em quatro quadrantes (0,25ha. Foram levantados os dados relativos às características físicas das áreas, das plantas e dos solos (0-20cm. Os resultados demonstraram que o araticum tende a ocorrer em maior densidade em Latossolos não concrecionários dos chapadões, em formação de cerrado típico. A área basal total das plantas entre as áreas em estudo é influenciada positivamente pela concentração de Ca, Mg e K no solo. A densidade de plantas de araticum é influenciada negativamente pela concentração de Fe no solo. A distância geográfica entre as áreas não influenciou na densidade de plantas, na área basal média e na área basal total das plantas de araticum.14 areas were selected in the State of Goiás, Brazil, with high occurrence of the araticum specie (Annona crassiflora Mart. and with smaller human being action possible. Each area had 1ha, and these areas were subdivided in four quadrants of 0,25ha. The relative data of the areas, plants and soils physical characteristics (0-20cm was collected. The results demonstrated that the araticum tends to happen in larger density in "latossolos" in "concrecionários" of the plains in formation of typical cerrado. The total basal area of the araticum plants among the areas in study is influenced positively by the concentration of Ca, Mg and K in the soil. The density of araticum plants is influenced negatively by the concentration of iron in the soil. The geographical distance among the areas did not influence the density of plants, in the medium and total basal area of the araticum plants.

  5. Larvicultura do Mandi-amarelo Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae em Diferentes Densidades de Estocagem nos Primeiros Dias de Vida

    Directory of Open Access Journals (Sweden)

    Luz Ronald Kennedy

    2002-01-01

    Full Text Available Este trabalho foi realizado na Estação de Piscicultura de São Carlos (EPISCar, São Carlos, SC. O efeito da densidade de estocagem de Pimelodus maculatus na larvicultura foi avaliado em pós-larvas alimentadas diariamente com zooplâncton selvagem na proporção de 300 organismos/pós-larva/dia e submetidas aos seguintes tratamentos: T1 - 5 pós-larvas/litro; T2 - 15 pós-larvas/litro; T3 - 30 pós-larvas/litro. No terceiro e quinto dias de experimento, foi avaliada a taxa de sobrevivência. Decorridos três dias de experimento, não foi observada influência da densidade na sobrevivência, embora, no quinto dia de experimento, houvesse maior sobrevivência na menor densidade testada, com valores médios de sobrevivência final de T1 (35,6%, T2 (28,9% e T3 (20,6%. Os maiores valores de peso foram encontrados no tratamento de menor densidade, sendo os valores de comprimento semelhantes entre os tratamentos. O tratamento contendo 30 pós-larvas/L apresentou as menores taxas de sobrevivência e a maior produtividade final.

  6. Rentabilidade da cultura da macieira cultivar Gala em duas densidades de plantio Investment return for Gala apple cultivar using two planting densities

    Directory of Open Access Journals (Sweden)

    Carlos Leomar Kreuz

    2002-03-01

    Full Text Available O presente trabalho discute, com base em um estudo de caso, a viabilidade econômica de ampliar a densidade de plantio de macieiras cultivar Gala de 1.000 plantas por hectare para 3.378 plantas por hectare. Os resultados mostraram que a taxa interna de retorno não variou (próxima de 1,61% ao mês, independentemente da densidade utilizada, o que sugere o uso da menor densidade de plantio, uma vez que esta requer um menor volume de recursos financeiros. O custo unitário de produção também se mantém praticamente o mesmo ao se variar a densidade de plantio.The present study was carried out to analyse economic performances of Gala apple orchards at different planting densities. Two orchard densities (1,000 and 3,378 plants/ha were evaluated in an orchard near Fraiburgo, SC, Brazil. The use of both planting densities resulted in the same internal rate of return (approximately 1.6% a month. It is suggested to use a lower planting system, once it requires less capital. Unit cost also remained the same for both planting densities used in this study.

  7. Reflexões acerca das nanotecnologias e as novas densidades técnicas-científicas-informacionais na agricultura

    Directory of Open Access Journals (Sweden)

    Soraia de Fátima Ramos

    2009-01-01

    Full Text Available As pesquisas sobre os potenciais usos das nanotecnologias no agronegócio suscitam enormes dúvidas sobre os reais benefícios ou malefícios em relação à adoção desta inovação. Daí a preocupação desta investigação em incluir as ciências humanas nos debates sobre a difusão das nanotecnologias. Pressupõe-se que, dada a efetiva incorporação dos novos produtos e processos nanotecnológicos, irá se configurar um aprofundamento das densidades técnicas-científicas- informacionais no espaço agrário brasileiro.

  8. EVALUACIÓN DE DENSIDADES DE PLANTACIÓN EN EL CULTIVO DE LA JAMAICA (Hibiscus sabdariffa L.)

    OpenAIRE

    Z. Terán; F. De Soto(Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Sevilla, Spain)

    2004-01-01

    La investigación se llevó a cabo en el Instituto Nacional de Ciencias Agrícolas (INCA), en el verano del 2001, con el objetivo de comparar seis distancias de plantación en el cultivo de la Jamaica ( Hibiscus sabdariffa L.) y su influencia en los rendimientos y sus componentes por superficie para definir la densidad óptima. Las distancias empleadas fueron: 1.20x1.00m; 1.20x0.90m; 1.00x1.00m; 1.00x0.90m; 0.90x0.90m y 0.90x0.80m; a esos marcos de plantación correspondieron las siguientes densida...

  9. Força muscular e densidade mineral óssea em idosos eutróficos e desnutridos

    OpenAIRE

    Karla Helena Coelho Vilaça; Eduardo Ferriolli; Nereida Kilza da Costa Lima; Francisco José Albuquerque de Paula; Julio Sérgio Marchini; Julio Cesar Moriguti

    2011-01-01

    OBJETIVO: Este estudo teve como objetivo avaliar a associação do estado nutricional com a força muscular de preensão manual e a densidade mineral óssea em idosos do sexo masculino. MÉTODOS: Participaram do estudo 41 idosos do sexo masculino, sendo 20 eutróficos (peso: M=69,6, DP=8,4; índice de massa corporal: M=25,7, DP=2,2) e 21 desnutridos (peso: M=50,9, DP=6,1; índice de massa corporal: M=18,7, DP=1,8), classificados subjetivamente segundo a Mini Avaliação Nutricional. A avaliação antropom...

  10. El funcional de densidad local: una aplicacion a problemas de física de la materia condensada

    OpenAIRE

    Takeuchi, Noboru

    2012-01-01

    Se presenta una breve introducción al funcional de densidad local. Esta teoría permite la simplificación de las ecuaciones matemáticas que describen la estructura electrónica de los átomos, moléculas y sólidos. Durante muchos años se han buscado métodos que permitan el entendimiento de cómo funcionan los enlaces entre átomos. Con el nacimiento de la mecánica cuántica a principios de los años 1900 se sentaron las bases, formulando las leyes que rigen el comportamiento a nivel atómico. Sin emba...

  11. Densidade do solo, atributos químicos e sistema radicular do milho afetados pelo pastejo e manejo do solo

    Directory of Open Access Journals (Sweden)

    V. R. Silva

    2000-03-01

    Full Text Available A integração lavoura-pecuária é uma alternativa de renda dos produtores no sul do Brasil. Entretanto, o pisoteio animal e, ou, o preparo de solo podem compactá-lo, prejudicando o crescimento radicular e a produtividade das plantas. Estudaram-se os efeitos do pisoteio animal em regime de pastejo contínuo durante o inverno/primavera e do impacto do plantio direto e do preparo convencional de solo no estado de compactação, atributos químicos e distribuição radicular. Em Podzólico Vermelho-Amarelo de textura superficial franca, foi implantada uma pastagem de estação fria composta por aveia (Avena strigosa Schreb e azevém (Lolium multiflorum L.. A carga animal variou conforme o crescimento da pastagem. Em dezembro de 1996, foi implantada a cultura do milho (Zea mays L. para a produção de silagem, usando os seguintes tratamentos: plantio direto na área não pastejada, plantio direto após o pastejo, preparo convencional de solo na área não pastejada e preparo convencional de solo após pastejo. As avaliações apresentadas neste estudo são referentes ao terceiro ano de cultivo, no qual houve um período de pastejo de 107 dias. Aos 45 dias da emergência do milho, foram abertas trincheiras (100 x 40 cm para visualizar a distribuição do sistema radicular e coletar amostras de solo, a cada 5 cm, para caracterização química e determinação da densidade do solo e de raízes. Ao longo do perfil (0-40 cm, o desenho da distribuição de raízes indicou maior quantidade de raízes no preparo convencional de solo, concordando com os resultados de densidade de raízes. O pisoteio animal não teve efeito sobre as características físicas, possivelmente pelo fato de o resíduo da pastagem permanecer próximo a 1,0 Mg ha-1 de matéria seca. A densidade do solo no plantio direto, na camada de 5-10 cm, foi de 1,41 Mg m-3, tanto na área pastejada como na não pastejada. No preparo convencional de solo, esses valores foram de 1,15 Mg m-3

  12. Densidad del Mono aullador Alouatta seniculus (Linnaeus, 1766 Mammalia: primates en el arroyo coloso, Departamento de Sucre, Colombia

    Directory of Open Access Journals (Sweden)

    Fajardo Patiño Alirio

    1996-12-01

    Full Text Available Nueve manadas de Alouatta seniculus, fueron estudiadas a lo largo de tres meses y medio, entre Mayo y Agosto de 1983. Se tomaron en cuenta aspectos relativos al estado y densidad poblacional en el Arroyo Colosó, Departamento de Sucre. Se establece una relación de los datos obtenidos y procesados en este trabajo con los suministrados por otros autores en estudios similares con la misma especie y en diferentes lugares.Nine troops of Alouatta seniculus, were studied for a period of three and half months betwen May and August of 1983. Relevant facts of the condition and population density in the Colosó stream, located in Sucre Deparment, were taken. A relation is stablished among the facts obtained and processed in this investigation with facts provided by another authors in similar studies with the same specie in different locations.

  13. AVALIAÇÃO AGROTECNOLÓGICA E DO CICLO DE VARIEDADES DE ABACAXIZEIRO, EM DUAS DENSIDADES, EM VOTUPORANGA (SP

    Directory of Open Access Journals (Sweden)

    ADEMAR SPIRONELLO

    1997-01-01

    Full Text Available Desenvolveu-se um experimento, no Noroeste paulista, em duas densidades de cultivo, com o objetivo de estudar as variedades de abacaxizeiro existentes no Estado, com potencial produtivo e de qualidade de fruto, e muito mais resistentes à fusariose que as duas comerciais, a saber: Smooth Cayenne, Pérola (únicas cultivadas comercialmente no Brasil e ambas muito suscetíveis à fusariose, Rondon e Turi Verde. As densidades de cultivo foram D1 = 60.606 plantas/hectare - linhas duplas de 30 x 30 x 80 cm, e D2 = 35.714 plantas/hectare - 40 x 40 x 100 cm. Efetuou-se o experimento em parcelas subdivididas, com as principais (densidades dispostas em blocos ao acaso com seis repetições. As subparcelas (variedades constaram de duas linhas duplas com doze plantas úteis. Mediram-se, em cada planta, os períodos de emissão natural da inflorescência, os tempos decorridos desde essa emissão até o início e o término de florescimento e, deste último, até a colheita. Determinaram-se as dimensões e a massa dos frutos e das coroas, o número de mudas produzidas e, na polpa dos frutos, o grau Brix, a acidez, o pH, o teor de vitamina C e de textura. A variedade Smooth Cayenne apresentou maior produtividade de frutos (47% e maior teor de sólidos solúveis da polpa (30% que a média de `Pérola' e `Rondon'. Os resultados indicam a viabilidade de utilização da `Rondon' no cultivo comercial, como opção para substituir a `Pérola'. O aproveitamento da soca das variedades foi viável apenas na `Rondon', que mostrou frutos precoces e pouco menores que os da primeira produção. A maior densidade de cultivo proporcionou, na média das variedades, maior produtividade de frutos (56%, menor massa média de frutos e de coroas (10% e menor número de filhotes por planta (14%.A field trial has been carried out at the Northwestern region of São Paulo State, aiming at studying four pineapple cultivars (Smooth Cayenne, Pérola, Rondon and Turi Verde in two plant

  14. On the synonymy of Stictocephala alta (Walker and Thelia constans Walker (Hemiptera: Membracidae Sobre a sinonímia de Stictocephala alta (Walker e Thelia constans Walker (Hemiptera: Membracidae

    Directory of Open Access Journals (Sweden)

    Gabriel Simões de Andrade

    2008-03-01

    Full Text Available This paper deals with the synonymy of Ceresa alta Walker, 1851, now Stictocephala alta, and its junior synonym, Thelia constans Walker, 1851. Notes on Stictocephala bisonia Kopp & Yonke, 1977 are also presented.São abordadas a sinonímia de Ceresa alta Walker, 1851, atualmente Stictocephala alta, e de Thelia constans Walker, 1851, como seu sinônimo júnior. Comentários sobre Stictocephala bisonia Kopp & Yonke, 1977 são apresentados também.

  15. Variabilidade Espacial e Densidade Amostral da Suscetibilidade Magnética e dos Atributos de Argissolos da Região de Manicoré, AM

    Directory of Open Access Journals (Sweden)

    Ivanildo Amorim de Oliveira

    2015-06-01

    Full Text Available A dificuldade em encontrar informações recentes sobre o comportamento espacial dos atributos dos solos na Região Amazônica tem sido preocupação de muitos pesquisadores. Em razão da grande dificuldade e dos custos para avaliar os atributos dos solos, têm-se utilizados métodos alternativos para predição de atributos do solo como a suscetibilidade magnética. Sendo assim, o objetivo deste trabalho foi avaliar a variabilidade espacial da suscetibilidade magnética (SM, os atributos físicos e químicos e determinar a densidade amostral de coleta em Argissolo Vermelho sob floresta nativa, Terra Preta Arqueológica (TPA sob cultivo, e pastagem na região de Manicoré, Amazonas. Nessas áreas, foram estabelecidas malhas com dimensão de 70 × 70 m e demarcados pontos nessas malhas, espaçados a cada 10 m, totalizando 64 pontos. Esses pontos foram georreferenciados e, em seguida, realizaram-se as coletas de solo em cada ponto da malha nas camadas de 0,00-0,20 e 0,40-0,60 m para determinar atributos químicos (pH em água, matéria orgânica, P, K, Ca, Mg e acidez potencial, físicos (textura, macroporosidade, microporosidade, diâmetro médio ponderado, densidade do solo e densidade de partículas e suscetibilidade magnética. Os dados foram submetidos à análise de variância, e as médias, comparadas pelo teste de Tukey a 5 %. Realizou-se a estatística descritiva. Para caracterizar a variabilidade, fez-se a geoestatística com uso de semivariograma escalonado. O alcance dos semivariogramas escalonados foi utilizado para determinar a densidade amostral mínima de coleta para estimar a variabilidade dos atributos estudados. As áreas de TPA e pastagem apresentaram maior variabilidade, apresentando menor alcance e maior densidade amostral (cinco pontos por hectare. A SM apresentou comportamento espacial similar aos atributos físicos e químicos estudados, sendo a densidade amostral da SM próxima à densidade amostral dos atributos nos

  16. Influencias de la densidad y podas sobre la producción de Pinus taeda L. a los 7 años de edad.

    Directory of Open Access Journals (Sweden)

    Rubén Costas

    2010-08-01

    Full Text Available En un ensayo con 3 niveles de densidad y 12 tratamientos de poda, se evaluaron los efectos de la densidad, la altura de poda, el número de levantes de poda y la interacción entre la densidad y las podas sobre la producción de la masa de Pinus taeda L. a los 7 años de edad. Las variables evaluadas fueron el diámetro a la altura de pecho medio (DAP, la altura media, el volumen individual, el volumen por unidad de superficie, el área basal, el diámetro máximo sobre muñón (DMSM, el coeficiente de forma de Girard (CFG, el diámetro de ramas (DRBC y el ángulo de inserción de las ramas (ARBC en la base de la copa. En los tratamientos con mayor densidad de plantación se observaron mayores volúmenes por unidad de superficie, área basal y CFG que en los tratamientos con menor densidad. Estos produjeron mayores DAP, volúmenes individuales, DMSM, DRBC y ARBC que los tratamientos con mayores densidades. Los tratamientos con menores alturas finales de poda produjeron mayores DAP, volúmenes individuales, área basal y volúmenes por unidad de superficie que los tratamientos con mayores alturas de poda. Los menores DMSM se obtuvieron con alturas finales de poda de 3,30 m y 4,40 m realizadas a los 4 años de edad y los mayores DMSM ocurrieron al no efectuarse podas a los 5 años hasta 5,50 m y 6,60 m. No se encontraron diferencias significativas entre los valores medios de DRBC, ARBC y CFG producidos por los 12 tratamientos de poda. La interacción entre densidad y los tratamientos de poda no fue significativa para ninguna de las variables respuestas.

  17. Niche conservatism of Eulophia alta, a trans-Atlantic orchid species

    Directory of Open Access Journals (Sweden)

    Marta Kolanowska

    2014-03-01

    Full Text Available The genus Eulophia embraces over 230 species distributed through the tropical and subtropical Africa, Asia, Australia and the Americas. In Neotropics it is represented by a sole species – E. alta. The aim of the presented study was to evaluate the difference between ecological niches occupied by American and African populations of this species based on the ecological niche modeling. The similarity between the glacial and present niches occupied by E. alta was calculated and the factors limiting the species occurrence were identified. Areas of seasonal tropical forest, tropical savanna and woodland served as refugia for the studied species during last glacial maximum and they were more widespread in Neotropics than in Africa. No significant niche shift after last glacial maximum was observed. The distribution of E. alta in its whole range is restricted mainly by temperature seasonality. The differences in the niches occupied by African and Neotropical populations of E. alta suggest preglacial disjunction of the species range and independent adaptation of both groups. Despite the significant range disjunction of E. alta the species is characterized by relatively high degree of niche conservatism.

  18. ENFERMEDADES Y COMPONENTES DE RENDIMIENTO EN LÍNEAS DE FRÉJOL BAJO TRES DENSIDADES DE SIEMBRA

    Directory of Open Access Journals (Sweden)

    Felipe Rafael Garc\\u00E9s-Fiallos

    2014-01-01

    Full Text Available El objetivo fue evaluar las enfermedades, el rendimiento y sus componen - tes en líneas de fréjol bajo tres distanciamientos de siembra. El trabajo se realizó durante la época seca del año 2011, en la Universidad Técnica Estatal de Quevedo (UTEQ, Quevedo, Ecuador. Se determinó la incidencia y severidad de la roya ( Uromyces appendiculatus y mustia hilachosa ( Rizoctonia solani en los estadíos R7 (formación en legumbres y R8 (llenado de legumbres, y después de la cosecha la incidencia de las pudriciones radiculares ( Macrophomina phaseolina y R. solani . Los componentes de rendimiento (número de nudos, legumbres, granos, granos por legumbre, legumbres estériles y granos por planta y peso de granos. Se empleó un Diseño de Bloques Completos al Azar (DBCA con doce tratamientos y tres repeticiones, con arreglo factorial de 4 (líneas promisorias x 3 (planta/m. Para la comparación entre las medias de los tratamientos se empleó la prueba de Tukey al 5% de probabilidad del error. Las líneas promisorias de fréjol EVG 06-103 y SER-03 presentaron menor intensidad de enfermedades. Un aumento en la densidad poblacional causó un acrecentamiento en la intensidad de la roya. Las líneas SER-08 y SER-03 obtuvieron la mayor productividad según la mayoría de componentes de rendimiento y peso de granos. Finalmente, el incremento de la densidad de plantas promovió reducción significativa en el número de legumbres, granos y granos por legumbre por planta, contrario al aumento observado en el peso de granos

  19. Evaluation of alcohol outlet density and its relation with violence Avaliação da densidade de pontos de vendas de álcool e sua relação com a violência

    Directory of Open Access Journals (Sweden)

    Ronaldo Laranjeira

    2002-08-01

    , buscou-se investigar a disponibilidade de bebidas alcoólicas em uma região densamente povoada e melhorar o entendimento sobre o acesso a essa substância, para que ações preventivas futuras possam beneficiar-se dessas informações. MÉTODOS: O estudo foi realizado em uma região do Município de São Paulo, SP, Brazil. Foram treinados 24 entrevistadores, moradores da região, para fazerem a coleta de dados. Foi selecionada uma área de 19 ruas, cobrindo uma distância de 3.7 km. Foi feito um perfil de cada ponto de venda de bebidas alcoólicas dessa região. RESULTADOS: Foram registrados 107 pontos de venda de álcool. O número de outras propriedades nessa região foi de 1.202. Duas medidas de densidade de pontos de venda podem ser calculadas: número de pontos de venda por kilômetro de rua (29 pontos/km e proporção de todas as propriedades de venda de álcool (1 em 12. CONCLUSÕES: Comparado a estudos internacionais principalmente de países desenvolvidos, a área estudada tem a mais alta densidade de pontos de vendas de álcool registrada na literatura médica. As informações sobre as vendas de álcool e os locais de venda contribuíram para melhorar o entendimento do acesso ao álcool na região estudada. Ações preventivas futuras poderão beneficiar-se dessas informações.

  20. DOSES DE NITROGÊNIO E DENSIDADES DE PLANTAS COM E SEM UM REGULADOR DE CRESCIMENTO AFETANDO O TRIGO, CULTIVAR OR-1 NITROGEN DOSES AND PLANT DENSITIES WITH AND WITHOUT A GROWTH REGULATOR AFFECTING WHEAT, CULTIVAR OR-1

    Directory of Open Access Journals (Sweden)

    Jeferson Zagonel

    2002-02-01

    Full Text Available Doses de nitrogênio e elevadas populações de plantas são utilizadas visando a obtenção de altas produtividades em trigo. Porém, estes fatores podem promover o acamamento das plantas, especialmente para as cultivares de porte médio ou alto. O uso de produtos que reduzem a estatura das plantas pode minimizar este problema. Visando avaliar o efeito do regulador de crescimento trinexapc-ethyl em diferentes populações de plantas e doses de nitrogênio, na cultivar de trigo OR-1, instalou-se um experimento na Fazenda Escola "Capão da Onça", da Universidade Estadual de Ponta Grossa, em Ponta Grossa, PR, no ano de 1999. O delineamento experimental foi blocos ao acaso em esquema fatorial 2 x 3 x 4, em quatro repetições. Os vinte e quatro tratamentos constaram da aplicação de 125 g i.a./ha de trinexapac-ethyl e testemunha; densidades de 55, 75 e 112 plantas/m no espaçamento de 0,17m entre fileiras e doses de 0, 45, 90 e 135kg/ha de nitrogênio em cobertura. A aplicação do trinexapac-ethyl resultou em plantas com entre-nós mais curtos; em aumento do número de espigas/m e da produtividade. Com o aumento da dose de nitrogênio, ocorreu aumento da estatura das plantas, do número de espigas/m e da produtividade. Com o aumento da densidade de plantas, o diâmetro do caule, a massa seca das plantas e o número de grãos por espiga diminuíram mas o número de espigas/m e o peso de mil grãos aumentaram, sem afetarem a produtividade. Não ocorreu acamamento em nenhum dos tratamentos.Elevated nitrogen rates and high plant populations are adopted with the purpose of achieving high wheat yields. However, these factors may promote the lodging of the plants, especially for the medium and tall height cultivars. The utilization of products which reduce plant height could minimize this problem. With the aim of evaluating the effects of a growth regulator on different plant populations and nitrogen rates for the wheat cultivar OR-1, an experiment was

  1. Measurement of tritium production rate distribution in natural LiAlO2/HDPE assembly irradiated by D-T neutrons

    International Nuclear Information System (INIS)

    A neutronics experiment was performed to measure the tritium production rate (TPR) profile in the breeder assembly with LiAlO2 as breeder and high density polyethylene (HDPE) as neutron reflector. The breeder assembly was irradiated with 14 MeV neutrons from DT neutron generator at IPR Neutronics Laboratory. The objective of the experiment was to validate the tritium production prediction capability of the Monte-Carlo code MCNP and FENDL 2.1 data library. The tritium production rate profile in the breeding assembly was measured by irradiating Li2CO3 pellets kept at various locations and then tritium counting liquid scintillation technique. Experiment was analyzed with 3D Monte-Carlo code MCNP with FENDL 2.1 cross-section data library. The calculation results were found to agree with the measured tritium production rates except one point near to the source. This experiment is a starting experiment in the series of benchmark experiments for the Indian Demo breeding blanket.

  2. Stress responses of juvenile matrinxã (Brycon amazonicus after transport in a closed system under different loading densities Respostas de estresse de matrinxã (Brycon amazonicus juvenil após transporte em sistema fechado sob diferentes densidades de carga

    Directory of Open Access Journals (Sweden)

    Janessa Sampaio de Abreu

    2008-08-01

    , a temperatura esteve em torno de 32°C, pH 6,5-6,78, a amônia total foi de 1,09-1,7mg L-1, a amônia não-ionizada foi de 3,58-9,33 x 10³mg L-1 e alcalinidade 134-165mg CaCO3 L-1. O cortisol plasmático e a glicose sanguínea aumentaram após o transporte nos peixes em todas as densidades ensaiadas, voltando aos valores controle 24h depois. Os valores de osmolaridade não mudaram logo após o transporte, mas aumentaram 24h depois de modo igual em todas as densidades. O cloreto plasmático diminuiu na chegada, de modo inversamente proporcional à densidade de carga. O hematócrito diminuiu 24h depois da chegada dos peixes, em todas as densidades testadas, mas não houve diferença no número de eritrócitos. Não houve mortalidade até uma semana após o transporte. O matrinxã mostrou ser uma espécie tolerante a altas densidades de carga em embalagens para transporte além de suportar baixos níveis de oxigênio na água.

  3. Consumo energético de sistemas de computación de altas prestaciones

    OpenAIRE

    Balladini, Javier; Morán, Marina; Rozas, Claudia; De Giusti, Armando Eduardo; Suppi, Remo; Rexachs del Rosario, Dolores; Luque, Emilio

    2015-01-01

    En la última década, el consumo energético ha dirigido el diseño de todos los sistemas de cómputo, desde dispositivos móviles a los cuales cada vez se le piden más prestaciones que deben ser soportadas por una pequeña batería, hasta los sistemas de Cómputo de Altas Prestaciones (HPC, de High Performance Computing), objeto de nuestro interés, los cuales consumen enormes cantidades de energía. Esta alta demanda energ ética tiene serias consecuencias financieras, medioambientales, y en muchos c...

  4. Papel de la enfermería en las hemorragias digestivas altas en urgencias y emergencias

    OpenAIRE

    Ibáñez García, Patricia

    2015-01-01

    La hemorragia digestiva alta es la complicación gastroenterológica más importante. Está delimitada por el esfínter esofágico superior y el ángulo de Treitz, es decir, es aquella que se produce en esófago, estómago o duodeno. El objetivo de esta revisión bibliográfica es conocer cuál es el papel que ejerce la enfermería ante una hemorragia digestiva alta en las emergencias extrahospitalarias y urgencias hospitalarias. Se diferencian dos tipos de hemorragias según la causa que las produzc...

  5. Estudo da miscibilidade das misturas de PHB e PLA, com um PHB de alta polidispersividade

    Directory of Open Access Journals (Sweden)

    Wagner Mauricio Pachekoski

    2015-02-01

    Full Text Available Neste trabalho, foi estudada a miscibilidade de misturas de um PHB constituído de frações de alta e baixa massa molar com um PLA de alta massa molar. Os materiais extrudados foram analisados pelas técnicas de calorimetria exploratória diferencial (DSC, espectroscopia dielétrica (DE e análises dinâmico-mecânicas (DMA. A partir dos resultados observou-se o distinto comportamento cristalino das frações de PHB, assim como a miscibilidade parcial do PLA com o PHB de baixa massa molar.

  6. Estudo da miscibilidade das misturas de PHB e PLA, com um PHB de alta polidispersividade

    OpenAIRE

    Wagner Mauricio Pachekoski; Carla Dalmolin; José Augusto Marcondes Agnelli

    2015-01-01

    Neste trabalho, foi estudada a miscibilidade de misturas de um PHB constituído de frações de alta e baixa massa molar com um PLA de alta massa molar. Os materiais extrudados foram analisados pelas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia dielétrica (DE) e análises dinâmico-mecânicas (DMA). A partir dos resultados observou-se o distinto comportamento cristalino das frações de PHB, assim como a miscibilidade parcial do PLA com o PHB de baixa massa molar.

  7. Computación de altas prestaciones: problemáticas y aplicaciones

    OpenAIRE

    Balladini, Javier; Morán, Marina; Rozas, Claudia; Frati, Fernando Emmanuel; De Giusti, Armando Eduardo; Suppi, Remo; Rexachs del Rosario, Dolores; Luque, Emilio

    2016-01-01

    Nuestra investigación está centrada en dos lí- neas. Por un lado, el estudio del consumo energé- tico de los sistemas de Cómputo de Altas Prestaciones (HPC, de High Performance Computing) cuya alta demanda energética tiene serias consecuencias nancieras, medioambientales, y en muchos casos también sociales. El aumento de la e ciencia energética de los sistemas de HPC no solo proviene de las nuevas arquitecturas hardware, también está involucrado el software, quien debe gestionar y con gurar ...

  8. ALTAS CAPACIDADES: COMPARATIVA ENTRE EL MODELO ESPAÑOL Y BRITÁNICO

    OpenAIRE

    Rodríguez-Vázquez, María

    2012-01-01

    El presente trabajo de investigación exploratoria reflexiona sobre el concepto de alumno con altas capacidades y propone una comparación legislativa entre el modelo de atención a los alumnos con altas capacidades británico y español y cómo ese modelo afecta al sistema educativo general, ya que aunque tienen puntos en común entre ambos países, pero se trata dos formas de enfocar completamente distintas. Además también pretende recoger información sobre iniciativas y proyectos que reflejen l...

  9. Altas capacidades: Proyecto educativo para el aula de Educación Primaria

    OpenAIRE

    López-Presedo, Iria Flavia

    2015-01-01

    El presente TFG tiene como principal finalidad dar una respuesta educativa, eminentemente práctica, al alumnado de altas capacidades dentro del grupo-clase. En primer lugar, se han revisado las teorías de varios autores sobre las altas capacidades, los métodos de detección e intervención con este tipo de alumnado y, finalmente, se ha elaborado un proyecto en forma de programa de enriquecimiento curricular. Este proyecto se inscribe dentro de la Teoría de las inteligencias múltiples de Gard...

  10. Altas capacidades intelectuales : investigación y propuesta desde las inteligencias múltiples

    OpenAIRE

    Pulido Vinuesa, Salomé

    2015-01-01

    El presente trabajo trata sobre las altas capacidades, investigando sobre ello acerca de su historia y evolución, los diversos tipos existentes, sus características, su identificación, su evaluación, sus metodologías, entre otros. Además, se ha realizado un resumen de cómo es tratada esta necesidad educativa por las leyes, antiguas y en vigor. De igual modo, se trata la educación inclusiva, ya que es un tema que afecta a alumnos/as con altas capacidades. El programa de intervención en rel...

  11. Procesos de fractura dinámica en hormigón de alta resistencia

    OpenAIRE

    Tarifa Crespo, Manuel Agustín

    2012-01-01

    El objetivo de la presente tesis se centra en el estudio de los procesos de fractura en régimen dinámico, de un material tan importante en grandes obras de ingeniería civil como es el hormigón de alta resistencia. Muchas son las investigaciones realizadas hasta la fecha sobre el comportamiento dinámico en fractura del hormigón convencional, pero muy pocas las llevadas a cabo sobre el hormigón de alta resistencia. En esta tesis se desarrolla un programa experimental dirigido a estudiar l...

  12. 50 años de alta velocidad en Japón

    OpenAIRE

    Pigem Cameselle, Ramiro

    2008-01-01

    Al inaugurar los 515 kilómetros de línea de alta velocidad entre Tokio y Osaka en octubre de 1964, Japón alcanzó un logro todavía mayor que el de impulsar su propia economía. Abrió una era del transporte completamente nueva con un innovador sistema ferroviario. Con ello prestó un innegable servicio al mundo ferroviario, desencadenando un auge global de la alta velocidad e inyectando aire fresco a una industriar que estaba en claro declive. Casi 50 años más tarde, los 210 km/h inic...

  13. Respostas lactacidêmicas de ratos ao treinamento intermitente de alta intensidade

    OpenAIRE

    Ana Carolina Panveloski-Costa; Marcelo Papoti; Rafael Junges Moreira; Patricia Monteiro Seraphim

    2012-01-01

    Durante contrações musculares de alta intensidade intervaladas por curtos períodos de tempo há importante participação do metabolismo glicolítico e, consequentemente, aumento das concentrações de lactato sanguíneo. O objetivo do estudo foi avaliar as respostas lactacidêmicas agudas e crônicas de ratos Wistar submetidos a um treinamento intermitente de alta intensidade (salto tipo jump squat) de três sessões semanais, a cada 24h, três séries de 12 repetições com intervalos de 60s entre cada um...

  14. Neurociências, altas habilidades e implicações no currículo

    OpenAIRE

    Amauri Betini Bartoszeck

    2014-01-01

    http://dx.doi.org/10.5902/1984686X14284O presente estudo inicialmente define e descreve as sub-disciplinas que compõem as neurociências com potenciais aplicações educacionais para crianças e adultos  identificados com altas habilidades. Objetiva-se com uma breve introdução morfofuncional ao sistema nervoso que serve de pano de fundo para auxiliar o entendimento da ponte teórico-experimental da relação de neurociências e altas habilidades. São salientados aspectos da base evolucionista e bioló...

  15. Densidad y preferencia de hábitat del perezoso de dos dedos Choloepus hoffmanni en un bosque andino (Bojacá, Cundinamarca, Colombia

    Directory of Open Access Journals (Sweden)

    Polanco Rocío

    2004-12-01

    Full Text Available Se estimó la densidad de perezosos de dos dedos Choloepus hoffmanni en un bosque andino fragmentado, a partir del conteo de restos fecales en parcelas fijas. Se caracterizó la vegetación del área y los árboles usados por los perezosos, con el fin de evaluar la preferencia de hábitat a dos escalas diferentes, así como la relación de las características del hábitat sobre la densidad de perezosos y la frecuencia de uso de los árboles. La densidad de perezosos en el área de estudio fue de 1,5 individuos/ha y varió entre tres fragmentos de bosque evaluados, diferentes en composición y estructura. Las densidades estimadas en las tres áreas de bosque resultaron
    en amplios intervalos de confianza, lo que es común a técnicas de conteo de heces. Aunque ninguna de las variables evaluadas de la vegetación explicó las diferencias de densidad entre bosques, el mayor desarrollo de la vegetación arbórea de una de las áreas de bosque dominado por Quercus humboldtii, y la evasión de la especie Miconia tonduzzi por los perezosos explicaría las diferencias en la densidad de perezosos, así como la evasión de una de las áreas de bosque. C. hoffmanni utiliza una gran variedad de especies arbóreas, pero con mayor frecuencia las especies Q. humboldtii y Brunellia tonduzii. Los árboles donde se realizaron avistamientos difieren de los árboles cercanos a restos fecales de Choloepus hoffmanni en cuanto a altura, DAP y porcentaje de la copa expuesta al sol. Ninguna de las variables evaluadas fue relevante para el uso
    de algunas especies de árboles con mayor frecuencia.

  16. Avaliação dos efeitos da adição de sal e da densidade no transporte de tambaqui

    Directory of Open Access Journals (Sweden)

    Gomes Levy de Carvalho

    2003-01-01

    Full Text Available Os objetivos deste trabalho foram testar a eficiência do sal como redutor de estresse e verificar a melhor densidade de transporte de juvenis de tambaqui (Colossoma macropomun em caixas de plástico adaptadas. No primeiro experimento foram testadas diferentes concentrações de sal de cozinha (NaCl na água; no segundo, o transporte foi realizado por três horas em caixas de plástico de 200 L estocadas com diferentes densidades de peixe, com 8 g de sal/L de água. O cortisol plasmático dos peixes sofreu aumento significativo após o transporte no tratamento sem sal e com 2 g de sal/L de água, retornando para níveis normais após 96 horas. A glicose plasmática dos peixes sofreu aumento após o transporte em todas as concentrações de sal testadas, com exceção da com 8 g/L de água, retornando para níveis normais em 24 horas. Nos peixes transportados no segundo experimento, com 8 g de sal/L de água, não foi verificada mudança significativa no cortisol plasmático, mas a glicose aumentou significativamente em todas as densidades após o transporte, retornando para níveis normais em 24 horas. Houve mortalidade de 11% em uma das repetições da densidade de 200 kg/m³ de água. Para o transporte com 8 g de sal/L de água, a densidade máxima deve ser de 150 kg/m³ de água. Nesta densidade os parâmetros físico-químicos de qualidade de água se mantêm com características adequadas, as respostas ao estresse são mínimas e não há mortalidade.

  17. Diseño de decodificadores de altas prestaciones para código LDPC

    OpenAIRE

    Angarita Preciado, Fabian Enrique

    2013-01-01

    En esta tesis se han investigado los algoritmos de decodificación para códigos de comprobación de paridad de baja densidad (LDPC) y las arquitecturas para la implementación hardware de éstos. El trabajo realizado se centra en los algoritmos del tipo de intercambio de mensajes para códigos estructurados los cuales se incluyen en varios estándares de comunicaciones. Inicialmente se han evaluado las prestaciones de los algoritmos existentes Sum-product, Min-Sum y las principales variantes de...

  18. 77 FR 35669 - AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Science.gov (United States)

    2012-06-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial... notice in the above-referenced proceeding of AltaGas Renewable Energy Colorado LLC application for...

  19. 77 FR 23712 - Alta Wind VII, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Science.gov (United States)

    2012-04-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Alta Wind VII, LLC; Supplemental Notice That Initial Market-Based Rate...-referenced proceeding of Alta Wind VII, LLC's application for market-based rate authority, with...

  20. Sistema de cómputo reconfigurable de alta performance (proyecto HPRC)

    OpenAIRE

    Kunysz, Eduardo; Rapallini, José Antonio; Osio, Jorge R.

    2015-01-01

    El objetivo de este trabajo es el estudio de las nuevas tendencias en cómputo paralelo con la finalidad de mejorar el rendimiento de cálculo. Cómo una alternativa interesante para optimizar la relación costo-prestaciones, se exploran tecnologías de computadoras de alta performance reconfigurable (HPCR).

  1. Grounding the past : the praxis of participatory archaeology in the Mixteca Alta, Oaxaca, Mexico

    NARCIS (Netherlands)

    Geurds, Alexander

    2007-01-01

    "Grounding the Past" addresses archaeological field praxis and its role in the political present of Santiago Tilantongo and Santiago Apoala, two communities in the Mixteca Alta region of Oaxaca, Mexico. Efforts to involve local stakeholder communities in archaeology have become an important issue wo

  2. La evaluación psicopedagógica del alumnado con altas capacidades

    OpenAIRE

    Grau Rubio, Claudia

    2012-01-01

    Se describen los instrumentos de evaluación psicopedagógica aplicables al alumnado con altas capacidades. Instrumentos referidos al alumno, al contexto escolar, a las variables socio-familiares y la determinación de las necesidades educativas especiales.

  3. Respostas lactacidêmicas de ratos ao treinamento intermitente de alta intensidade

    Directory of Open Access Journals (Sweden)

    Ana Carolina Panveloski-Costa

    2012-04-01

    Full Text Available Durante contrações musculares de alta intensidade intervaladas por curtos períodos de tempo há importante participação do metabolismo glicolítico e, consequentemente, aumento das concentrações de lactato sanguíneo. O objetivo do estudo foi avaliar as respostas lactacidêmicas agudas e crônicas de ratos Wistar submetidos a um treinamento intermitente de alta intensidade (salto tipo jump squat de três sessões semanais, a cada 24h, três séries de 12 repetições com intervalos de 60s entre cada uma. Houve aumento das concentrações de lactato sanguíneo durante a sessão aguda do treinamento (lactacidemia basal vs. lactacidemia após último esforço, P < 0,001. Contrariamente, após seis semanas de treinamento, ocorreu redução de 49% na resposta lactacidêmica ao exercício em relação à primeira sessão, P = 0,0002. O exercício intermitente de alta intensidade intervalado favorece a participação do sistema glicolítico; no entanto, o treinamento intermitente de alta intensidade promove redução das respostas lactacidêmicas, sugerindo melhora da capacidade de ressíntese de fosfocreatina e da biogênese mitocondrial.

  4. Pneumonia lipoídica em adultos: aspectos na tomografia computadorizada de alta resolução Lipoid pneumonia in adults: findings on high-resolution computed tomography

    Directory of Open Access Journals (Sweden)

    Edson Marchiori

    2007-10-01

    Full Text Available OBJETIVO: Apresentar os aspectos na tomografia computadorizada de alta resolução do tórax da pneumonia lipoídica exógena por aspiração de óleo mineral, em pacientes adultos MATERIAIS E MÉTODOS: Foram estudados oito pacientes adultos - quatro mulheres e quatro homens - com média de idade de 69,4 anos, todos usuários de óleo mineral para tratamento de constipação intestinal. Os exames foram avaliados por dois radiologistas, de forma independente RESULTADOS: Os achados tomográficos mais comuns foram as consolidações com áreas de densidade de gordura de permeio, e o padrão de pavimentação em mosaico. As lesões foram bilaterais em seis pacientes, e unilaterais em dois CONCLUSÃO: O encontro de consolidações pulmonares com áreas de densidade de gordura de permeio, associado à história clínica do uso de óleo mineral, é diagnóstico de pneumonia lipoídica exógena.OBJECTIVE: The present study was aimed at describing the findings on high-resolution computed tomography in patients with exogenous lipoid pneumonia secondary to mineral oil aspiration MATERIALS AND METHODS: Eight adult patients - four men and four women - with mean age of 69.4 years were studied. All of the patients were users of mineral oil for treating intestinal constipation. High-resolution computed tomography studies of these patients were blindly evaluated by two radiologists. RESULTS: Air-space consolidation with areas of fat density and crazy paving pattern were the most frequent findings. The lesions were bilateral in six cases and unilateral in two CONCLUSION: Air-space consolidation with areas of fat density, associated with a clinical history of mineral oil ingestion virtually indicates a diagnosis of exogenous lipoid pneumonia.

  5. INFLUENCIA DE LA ALTA TEMPERATURA EN LOS TEJIDOS RADICULARES DE TOMATE (Lycopersicon esculentum Mill.

    Directory of Open Access Journals (Sweden)

    Ofelia Sam

    2006-01-01

    Full Text Available Los cambios cualitativos en los tejidos radiculares, como consecuencia de la alta temperatura empleada en este trabajo (38oC durante 1.5 horas, fueron estudiados en plántulas de dos variedades de tomate (Lycopersicon esculentum Mill., con diferentes grados de tolerancia a altas temperaturas. A los siete días de puestas a germinar las semillas de arroz, se aplicó el tratamiento de alta temperatura a las radículas de cada variedad, que fueron puestas en recipientes con agua, por separado, y colocadas en la estufa durante 1.5 h a 380C y el tratamiento control consistió en dejar al otro grupo de radículas en las condiciones del laboratorio durante la aplicación de la alta temperatura; a continuación se tomaron las muestras de radículas, que fueron procesadas para microscopía de luz, incluidas en resina epon y se realizaron cortes de 2 ¿m de grosor, los que fueron teñidos con azul de toluidina, observados y fotografiados en un microscopio con cámara digital acoplada. En las secciones longitudinales de las radículas, se pudo apreciar que la alta temperatura provocó aumento en el tamaño de las vacuolas y dilatación de las paredes celulares, entre otras alteraciones; estos cambios se hicieron más evidentes en la variedad considerada como tolerante a ese estrés.

  6. Análise de agrupamento de diferentes densidades de marcadores no mapeamento genético por varredura genômica

    OpenAIRE

    Marcelo Jangarelli; Ricardo Frederico Euclydes; Cosme Damião Cruz; Paulo Roberto Cecon; Antonio Policarpo Souza Carneiro

    2010-01-01

    A simulação tem contribuído para o avanço da genômica nas diversas áreas do melhoramento genético. Foram simulados mapeamentos genéticos utilizando diferentes densidades de marcadores para estimar os valores fenotípicos na seleção assistida por marcadores (SAM), em características quantitativas com valores de herdabilidade de 0,10; 0,40; e 0,70. Procedeu-se a análise de agrupamento com os desempenhos fenotípicos, cuja finalidade foi obter estruturas de classificação entre as densidades visand...

  7. Heliconia acuminata reproductive success is independent of local floral density O sucesso reprodutivo de Heliconia acuminata é independente da densidade floral local

    Directory of Open Access Journals (Sweden)

    Emilio M. Bruna

    2004-09-01

    Full Text Available Reproductive plants in tropical forests are patchily distributed, with some in large aggregations of reproductive consepecifics while others are relatively isolated. This variation in floral density is hypothesized to have a major effect on plant reproductive success, since individuals in higher density neighborhoods can attract more or higher quality pollinators. We experimentally tested this hypothesis with populations of the understory herb Heliconia acuminata in central Amazonia. We created replicated plots in which reproductive plant density spanned the range of naturally occurring floral neighborhood size, then measured three surrogates of plant fitness in focal plants in each array. There was no significant difference between any of the three floral neighborhood treatments in total seed production, fruit set, or the number of seeds produced per fruit. Pollinator visitation rates to plants in all treatments were extremely low, with many plants not visited at all during the observation period. This could be because H. acuminata's hummingbird pollinators are unable to find the widely scattered reproductive plants, however this hypothesis appears unlikely. Instead, natural flowering plant densities may simply be below the threshold value at which neighborhood effects become important, even in "high-density" aggregations. Nutrient limitation, selective fruit abortion, and reproduction via male rather than female function may also be playing a role. We argue the absence of neighborhood effects may be a general phenomenon in central Amazonian forests, though additional experiments with other plant-pollinator systems are needed to determine the extent to which this hypothesis is supported.Plantas reprodutivas em florestas tropicas são distribuidas em manchas, com algumas em grandes agregações coespecíficas e outras relativamente isoladas. A hipótese é que esta variação na densidade de flores em um local tem um grande efeito no sucesso

  8. Efecto de la densidad de siembra y la adición de ácido ascórbico en el cultivo de Osteoglossum bicirrhosum

    OpenAIRE

    Carolina Cuaical T.; Evelyn Vallejo V.; Hugo Franco R.; Wilmer Sanguino O.

    2015-01-01

    RESUMENObjetivo. Evaluar el efecto de la densidad de siembra y la adición de ácido ascórbico en la alimentación de alevinos de O. bicirrhosum, cultivados en jaulas. Materiales y métodos. Se incluyeron 396 alevinos y se distribuyeron en nueve tratamientos, resultado de la combinación de los niveles del factor densidad de siembra: 1pez/5 L; 1pez/10 L y 1pez/15 L y los niveles de ácido ascórbico: 0; 500 y 1000 mg/kg. Los datos obtenidos se evaluaron mediante el análisis de varianza del diseño fa...

  9. Rendimiento de maíz forrajero en respuesta a fertilización nitrogenada y densidad de población

    OpenAIRE

    José Antonio Cueto Wong; David Guadalupe Reta Sánchez; José Luis Barrientos Ríos; Guillermo González Cervantes; Enrique Salazar Sosa

    2006-01-01

    En este estudio se determinó el efecto de la densidad de población y dosis de fertilización nitrogenada sobre el rendimiento y eficiencia de uso de nitrógeno en maíz (Zea mays L.) forrajero durante el ciclo de verano en la Comarca Lagunera, México, mediante dos experimentos, uno en 1998 y otro en 1999. Se estudiaron tres dosis de fertilización nitrogenada (125, 250 y 375 kg ha-1) y cinco densidades de población (9.0, 12.0, 15.0, 18.0 y 21.0 plantas/m2 en 1998; y 8.5, 11.0, 13.5, 16.0 y 18.5 p...

  10. DENSIDAD DE POBLACIÓN Y FERTILIZACIÓN NITROGENADA EN LA PRODUCCIÓN DE SEMILLA HÍBRIDA DE MAÍZ

    OpenAIRE

    Francisco Cervantes-Ortíz; Jorge Covarrubias-Prieto; José Antonio Rangel-Lucio; Arturo Daniel Terrón-Ibarra; Mariano Mendoza-Elos; Ricardo Ernesto Preciado-Ortiz

    2013-01-01

    El presente estudio tuvo como objetivo determinar el efecto de la densidad de población y la fertilización nitrogenada en el rendimiento y calidad de semilla híbrida de maíz. El experimento se realizó en el Instituto de Nacional de Investigaciones Forestales, Agrícolas y Pecuarias-Campo Experimental Bajío (INIFAP-CEBAJ), en el ciclo P-V 2009. En la cruza CML 142 x CML 176, progenitor femenino del híbrido H-374C, se evaluaron tres densidades de población (60, 75 y 90 mil plantas/ha) y tres niv...

  11. Aplicación de relaciones de densidad-diámetro y de área potencial aprovechable en bosques de Nothofagus Dombeyi (mirb.) Oerst, como herramientas de planificación silvícola .

    OpenAIRE

    Cruz Johnson, Pablo Christian

    2013-01-01

    Uno de los objetivos de esta tesis de doctorado fue analizar la aplicación de relaciones de densidad ¿ diámetro en bosques de Nothofagus dombeyi (Mirb.) oerst, para la localidad del Río Mirta en la XI Región de Chile, como herramientas de planificación silvícola. El método de análisis consistió en la generación de una muestra de densidad¿diámetro a partir de la que se determinó el índice de densidad máximo (IDmax) a partir del cual se estimaron las máximas densidades que la especie podría alc...

  12. Variação da densidade anofélica com o uso de mosquiteiros impregnados com deltametrina em uma área endêmica de malária na Amazônia Brasileira Variation of anopheles density with deltamethrin-impregnated mosquito nets in an endemic malaria area of the Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    João Barberino Santos

    1999-04-01

    Full Text Available Em 1992, foi realizado um ensaio de campo com mosquiteiros impregnados com deltametrina, em uma área endêmica de malária no Município de Costa Marques, Rondônia. No período de baixa transmissão, os mosquiteiros impregnados (MI diminuíram a densidade vetorial no intradomicílio, de modo semelhante, porém, aos mosquiteiros não impregnados (NI na maioria das avaliações-controle. Por outro lado, na época de alta transmissão, os MI provocaram diminuição significante da média horária de anofelinos capturados, ao passo que, nas casas com NI, verificou-se aumento do número de mosquitos capturados. No peridomicílio, em geral, não houve diferença do número de anofelinos capturados entre MI e NI. No grupo MI, a espécie mais capturada foi o An. darlingi (63,2%, mais freqüente no peridomicílio, seguida pelo An. deaneorum (35,3%, mais freqüente no intradomicílio. Os MI diminuíram a densidade vetorial no intradomicílio pelo efeito excito-repelente, sem diminuí-la, contudo, no peridomicílio.In 1992 a survey on the use of deltamethrin-impregnated mosquito nets was conducted in the municipality of Costa Marques, Rondonia. In the intradomicile, impregnated nets decreased the vector density at rates similar to those for non-impregnated nets during low-transmission periods; during high anopheline density periods, they led to a significant reduction in vector density, while in the non-impregnated net group there was an increase in the number of anophelines captured. There was no change in vector density in the peridomicile. In the impregnated net group, the most frequently captured species was Anopheles darlingi (63.2%, found mostly in the peridomicile, while Anopheles deaneorum (35.3% was most frequent indoors. The impregnated mosquito nets' excitatory-repellent effect decreased the intradomiciliary vector density but did not alter density in the peridomicile.

  13. Influência da densidade de estocagem no cultivo de juvenis de robalo-flecha mantidos em laboratório

    Directory of Open Access Journals (Sweden)

    Souza-Filho José Jerônimo de

    2003-01-01

    Full Text Available O objetivo deste trabalho foi analisar a influência da densidade de estocagem no crescimento, conversão alimentar e sobrevivência de juvenis de robalo-flecha (Centropomus undecimalis. Os peixes foram coletados em ambiente natural e treinados a aceitar dietas artificiais. Os indivíduos, com comprimento total de 13±0,4 cm e peso de 23±0,3 g foram estocados em tanques circulares de fibra de vidro de 5 m³, com água do mar e aeração contínua, nas densidades de 3, 6 e 9 peixes/m³, por 180 dias. Os valores de amônia total (0 a 0,5 mg/L, temperatura da água (23,3 a 30,6ºC, salinidade (17 a 34 g/L, pH (7,8 a 8,4 e oxigênio dissolvido (4,8 a 6,9 mg/L apresentaram padrão similar entre os tratamentos. A conversão alimentar (1,88, 2,06 e 2,31 e a sobrevivência (100%, 98,9% e 96,3% foram significativamente melhores nos tratamentos com 3 e 6 peixes/m³. As médias finais de peso (110, 87 e 80 g e comprimento total (20, 18,5 e 18 cm apresentaram diferença significativa. A maior taxa de crescimento foi observada com 3 peixes/m³; entre as demais não houve diferença. Entretanto, a biomassa final (332, 511 e 703 g/m³ foi diretamente proporcional à densidade. A baixa densidade favorece o cultivo do robalo em relação ao crescimento, sobrevivência e conversão alimentar.

  14. Densidad y distribución sobre CSMA/CA en redes IEEE 802.11g en modo AD HOC

    Directory of Open Access Journals (Sweden)

    José Domínguez

    2010-09-01

    Full Text Available El propósito  principal de la presente investigación, fue determinar la influencia de la densidad y distribución de hosts sobre el control de acceso al medio en redes IEEE 802.11g, tomando como variables fundamentales la densidad y distribución de los mismos y el protocolo CSMA/CA para el acceso al medio de transmisión.  La investigación fue de tipo explicativa, con un diseño  experimental puro. La misma se basó en los postulados teóricos de Bates (2003, Comer (2000, León García (2001, Stallings (2005, Tanenbaum (2003, entre otros. El procedimiento a utilizar fue diseñado por el investigador y consistió de cuatro (04 fases: Enfoque teórico, experimentación, Recolección y análisis de los datos y elaboración de conclusiones y recomendaciones.  La cantidad de hosts a utilizar en la red se ubicó en seis 06 equipos portátiles con especificaciones técnica similares. Para la recolección de la información se diseño un (1 instrumento, tipo formato de datos, en el cual se registraron diez (10 parámetros diferentes para evaluar el desempeño de la red en diversos escenarios. Seguidamente se tabularon los datos en cuadros, para proceder al análisis cuantitativo de los mismos. Se concluye que la densidad y distribución de los hosts en redes IEEE 802.11g afectan el acceso al medio de transmisión.Palabras clave: Densidad, distribución, red, ad hoc, control de acceso al medio.

  15. Participação do colmo principal e dos afilhos na produtividade do arroz irrigado, em função da densidade de semeadura

    Directory of Open Access Journals (Sweden)

    Eduardo do Valle Lima

    2010-01-01

    Full Text Available Entre as práticas culturais a serem consideradas na implantação da cultura do arroz destaca-se a densidade de semeadura, que deve estabelecer, em grande parte, a participação do colmo principal e dos afilhos nos componentes da produção, possibilitando a obtenção da máxima produtividade. O trabalho teve como objetivo avaliar a participação do colmo principal e dos afilhos na produtividade de grãos de arroz, cv. IAC 102, no sistema irrigado por inundação, em função da densidade de semeadura. O experimento foi desenvolvido sob túnel plástico, em Botucatu (SP, em caixas d'água de cimento amianto de 500 L, contendo Neossolo Flúvico Ta Eutrófico, com profundidade de 30 cm. O delineamento experimental foi o inteiramente casualizado, com quatro repetições. As densidades de semeadura foram: 100, 200, 300, 400, 500 e 600 sementes viáveis por m², em 4 linhas de 1 m por caixa, espaçadas com 20 cm. A elevação da densidade de semeadura diminui o afilhamento e proporciona a maior participação dos colmos principais, porém, não resultando em incremento de produtividade, devido à plasticidade das plantas de arroz, que proporciona o ajustamento dos componentes da produção.

  16. Estudio del comportamiento durante la sinterización de mezclas WC-Co finas, ultrafinas y nanocristalinas obtenidas por molienda de alta energía

    Directory of Open Access Journals (Sweden)

    Salvador, M. D.

    2008-10-01

    Full Text Available In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well as commercial nanopowders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and microstructurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM. The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 1800 HV.

    En este trabajo se ha estudiado el comportamiento, durante la sinterización, de mezclas WC-12Co finas, ultrafinas y nanométricas obtenidas por molienda de alta energía y de material nanométrico comercial, a fin de evaluar el efecto del tamaño de partícula y del proceso de obtención del polvo en la densificación, desarrollo microestructural y propiedades mecánicas del producto final. La consolidación de las mezclas se ha realizado mediante compactación uniaxial y sinterización en vacío y por compactación isostática en caliente. Los materiales sinterizados se han evaluado mediante medidas de densidad, dureza y tenacidad a fractura por indentación y se han caracterizado microestructuralmente mediante microscopía óptica y microscopía electrónica de barrido y de transmisión. Los resultados obtenidos ponen de manifiesto las mejoras en comportamiento resistente de los materiales obtenidos a partir polvos nanométricos, a

  17. EFECTOS DE LA DENSIDAD DE SIEMBRA Y FERTILIZACIÓN SOBRE LA BACTERIOSIS DEL PALMITO DE PEJIBAYE (Bactris gasipaes K.

    Directory of Open Access Journals (Sweden)

    Francisco Paulo Chaimsohn

    2008-01-01

    Full Text Available Se determinó el efecto de la densidad (3.333, 5.000 y 6.666 plantas/ha, el arreglo de siembra (rectangular y triangular y el tipo de fertilización (químico, orgánico y químico-orgánico sobre la incidencia y severidad de la enfermedad conocida como "bacteriosis del palmito", causada por la bacteria Pantoea stewartii (sin. Erwinia stewartii y el hongo Fusarium sp, en el periodo de julio de 2004 a agosto de 2005, en Guápiles, Costa Rica. El porcentaje de incidencia de la enfermedad varió de 14,1 a 80,8%. En las parcelas con el arreglo triangular hubo menor porcentaje de plantas enfermas. El porcentaje de incidencia de la bacteriosis fue mayor en las cepas de las parcelas fertilizadas con abono químico, seguido de aquellas fertilizadas con abono químico-orgánico y enmienda orgánica. La enfermedad se correlacionó de forma inversa a los contenidos de Ca, Mg, Zn, K y Mn del suelo, y al contenido foliar de Mn. Por otra parte, se correlacionó de forma directa con el contenido de Al del suelo, con los contenidos foliares de B y Cu, y con el porcentaje de interceptación de la radiación solar.

  18. DENSIDADES Y PROPIEDADES VOLUMÉTRICAS DE LA MEZCLA N,N-DIMETILFORMAMIDA (DMF + 1-BUTANOL A DIFERENTES TEMPERATURAS

    Directory of Open Access Journals (Sweden)

    MANUEL PÁEZ

    2013-01-01

    Full Text Available Se determinaron las densidades de la mezcla binaria de N,N-Dimetilformamida (DMF + 1-Butanol usando un densímetro de tubo vibrador DMA 5000, sobre todo el intervalo de fracciones molares en el intervalo de temperaturas de 283.15K a 313.15K y 1.011 bar. Se calcularon los volúmenes molares de exceso (V e m volúmenes molares parciales (Vi, volúmenes molares parciales a dilución infinita (V i ∞ , volúmenes molares parciales de exceso ( V i E del soluto y del solvente. Los volúmenes molares de exceso se correlacionaron usando la ecuación de Redlich-Kister. Adicionalmente, se calcularon los coeficientes viriales (bv de acuerdo a la teoría de McMillan-Mayer. Los valores obtenidos para estos parámetros fueron discutidos en términos de las interacciones presentes en solución.

  19. Espaçamento, densidade e uniformidade de semeadura na produtividade e características agronômicas da soja

    Directory of Open Access Journals (Sweden)

    Tourino Maria Cristina Cavalheiro

    2002-01-01

    Full Text Available O objetivo do presente estudo foi avaliar o efeito do espaçamento entre linhas (45 e 60 cm, da densidade das plantas nas linhas (10, 13, 16, 19 e 22 plantas m-1 e da uniformidade da semeadura (espaçamentos aceitáveis 25%, 35%, 60% e 100%, sobre a produtividade da soja. O experimento foi conduzido nos anos 1997/1998 e 1998/1999, com a cultivar CAC-1. O delineamento experimental utilizado foi o de blocos ao acaso, com três repetições, com os tratamentos em esquema de parcelas sub-subdivididas. Houve aumento na produtividade da soja no espaçamento de 45 cm com a redução da densidade para 10 plantas m-1, e com a uniformidade de espaçamento entre plantas dentro das linhas acima de 60%. A altura das plantas e o grau de acamamento foram reduzidos significativamente; porém, a porcentagem de sobrevivência das plantas aumentou à medida que ocorreu redução da densidade populacional das plantas. Também foi detectado que o aumento da uniformidade de espaçamento entre as plantas dentro das linhas reduziu-lhes o acamamento.

  20. Variação da densidade básica da madeira de progênies de Eucalyptus urophylla em dois locais.

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Mourão Brasil

    2009-09-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 Estudou-se neste trabalho a variação da densidade básica da madeira entre procedências e progênies de eucalipto plantados em duas localidades. As progênies de Eucalyptus urophylla originárias da ilha de Timor na Indonésia foram plantadas em Belo Oriente (MG e Linhares (ES no delineamento de blocos compactos em famílias (compact family blocks com 3 repetições no espaçamento de 3,0 x 2,0m. Após 4 anos as  árvores  foram amostradas ao nível do DAP com a sonda Pressler e sua densidade básica determinada pelo método do máximo teor de umidade. Os resultados mostraram que as progênies tiveram  comportamento similar nos dois locais. A maior variação entre progênies ocorreu naquelas provenientes da região Oebaha II. Os valores médios de densidade básica* das progênies não foram diferentes das procedências brasileiras utilizadas como testemunhas no experimento.

  1. Implementación de un protocolo de alta precoz en pacientes con hemorragia digestiva alta y bajo riesgo de resangrado (1996-2000)

    OpenAIRE

    Ramón Vila, Begoña de

    2004-01-01

    INTRODUCCIÓN:La hemorragia digestiva alta (HDA) es una urgencia médica frecuente. El pronóstico de los pacientes con HDA, así como la duración de la estancia hospitalaria, vienen determinados en gran medida por la persistencia o recidiva de la hemorragia. En los últimos años, varios autores han desarrollado una serie de sistemas de puntuación, basados en criterios clínicos y endoscópicos, para tratar de predecir el riesgo de resangrado o persistencia. Basándonos en el algoritmo propuesto por ...

  2. Implementación de un protocolo de alta precoz en pacientes con hemorragia digestiva alta y bajo riesgo de resangrado (1996-2000)

    OpenAIRE

    Ramón Vila, Begoña de

    2004-01-01

    [spa] INTRODUCCIÓN: La hemorragia digestiva alta (HDA) es una urgencia médica frecuente. El pronóstico de los pacientes con HDA, así como la duración de la estancia hospitalaria, vienen determinados en gran medida por la persistencia o recidiva de la hemorragia. En los últimos años, varios autores han desarrollado una serie de sistemas de puntuación, basados en criterios clínicos y endoscópicos, para tratar de predecir el riesgo de resangrado o persistencia. Basándonos en el algoritmo propues...

  3. Percepção de cuidadores familiares sobre um programa de alta hospitalar Percepciones de los cuidadores familiares sobre el programa de preparo de alta hospitalar Family caregivers' perception about a program of hospital discharge

    OpenAIRE

    Alesssandra Mendonça Cesar; Beatriz Regina Lara dos Santos

    2005-01-01

    O preparo de alta hospitalar, enquanto uma estratégia de Educação em Saúde, pode contribuir para a família dar continuidade aos cuidados no contexto domiciliar, após a alta hospitalar. Este estudo descritivo com abordagem qualitativa objetiva analisar a percepção do cuidador familiar de idosos com Acidente Vascular Cerebral (AVC) em relação a um programa de preparo de alta em um hospital universitário, para isso 12 cuidadores familiares foram entrevistados. Os dados foram analisados conforme ...

  4. Densidade de estocagem de juvenis de tambaqui durante a recria em tanques-rede Stocking density of tambaqui juveniles during second growth phase in cages

    Directory of Open Access Journals (Sweden)

    Franmir Rodrigues Brandão

    2004-04-01

    Full Text Available O objetivo deste trabalho foi determinar a densidade de estocagem mais adequada para a fase de recria de juvenis de tambaqui (Colossoma macropomum em tanque-rede. Foram utilizados 12 tanques-rede de 1 m³ cada, com peixes distribuídos nas densidades de 200, 300, 400 e 500 peixes/m³ em três repetições. Os peixes foram alimentados seis vezes por semana em três refeições diárias com ração comercial com 36% de proteína bruta, durante 60 dias. Foram analisados o crescimento em peso e em comprimento, o coeficiente de variação do comprimento, a taxa de crescimento específico e a glicose sanguínea aos 30 e 60 dias de criação. Ao final do experimento, foram analisados os seguintes parâmetros de produtividade: sobrevivência, conversão alimentar aparente, ganho de peso e produção por área. Os parâmetros físico-químicos da água foram avaliados a cada sete dias. O crescimento em peso e em comprimento, aos 60 dias, foi maior na densidade de 200 peixes/m³ do que na de 500 peixes/m³. O coeficiente de variação, a taxa de crescimento específico e a glicose não diferiram entre as densidades aos 30 e 60 dias. A sobrevivência final, a conversão alimentar aparente e o ganho de peso foram iguais em todas as densidades. A produção por área foi significativamente maior nas duas maiores densidades. Os resultados indicaram que a densidade de 400 peixes/m³ é a mais adequada para recria de juvenis de tambaqui em tanque-rede.The objective of this work was to determine the adequate stocking density to second growth phase of tambaqui (Colossoma macropomum juveniles in cage. Twelve cages of 1 m³ were used to stock fish in four different densities, with three replicate: 200, 300, 400 and 500 fish/m³. Fish were fed with commercial diets with 36% of crude protein six times a week, in three daily meals during 60 days. The growth in weight and in length, coefficient of variation of length, specific growth rate and glucose were analyzed at

  5. Recomendaciones europeas para el empleo de tornillos de alta resistencia en las estructuras de acero

    Directory of Open Access Journals (Sweden)

    Batanero, J.

    1962-10-01

    Full Text Available Con el enlace de los perfiles de acero por medio de tornillos de alta resistencia, pretensados, se ha introducido en la construcción metálica un nuevo tipo de uniones, que resisten por rozamiento. Los tomillos de alta resistencia (exceptuados los calibrados deberán quedar en el agujero con una cierta holgura; y, mediante apretadura de la tuerca o de la cabeza, tensarse en forma que las superficies de contacto de las piezas unidas quedan fuertemente presionadas, una contra otra, muy especialmente en las proximidades del agujero. Con ello el esfuerzo que actúa perpendicularmente al eje del tomillo es resistido por el rozamiento estático entre las superficies unidas; en tanto que, como consecuencia, la espiga del tomillo queda sometida a una tracción axil y a una torsión.

  6. Metais pesados, densidade e atividade microbiana em solo contaminado por rejeitos de indústria de zinco

    Directory of Open Access Journals (Sweden)

    H. E. Dias-Júnior

    1998-12-01

    Full Text Available As atividades relacionadas com mineração e indústria metalúrgica são responsáveis pela poluição de extensas áreas de solo em todo o mundo, sendo seus efeitos ainda pouco conhecidos nas condições brasileiras. No presente trabalho, os teores totais e solúveis em água de metais pesados, a densidade e a atividade microbiana foram avaliados em 1996, em sete locais de uma área de deposição de rejeitos da industrialização de zinco, em elevado estádio de degradação, e num local fora da área contaminada, considerado como referência, no estado de Minas Gerais. Todos os locais contaminados apresentaram elevados teores de metais pesados totais e solúveis em água, atingindo, respectivamente, os seguintes valores máximos, em mg kg-1: 11.969 e 726 de Zn; 109 e 18 de Cd; 1.016 e 0 de Pb e 887 e 8 de Cu. Todas as características biológicas avaliadas foram afetadas pelos elevados teores de metais com exceção do número de amonificadores. O C-biomassa apresentou redução acima de 80% em quatro locais contaminados em relação ao local fora da área contaminada. A respiração basal do solo foi maior no local contaminado coberto com Andropogon sp. e menor nos sítios sem vegetação. O número de actinomicetos e de fungos cultiváveis foi menos afetado pela contaminação que o número total de bactérias. Azospirillum spp. foram detectados apenas no local de referência. Oxidantes de amônio foram verificados em somente dois locais que continham vegetação, enquanto os oxidantes de nitrito foram detectados na maioria dos locais amostrados. Verificou-se a tendência de maior densidade e atividade microbiana nos locais contaminados e com algum tipo de vegetação. A concentração total e solúvel de Zn, de Cd e de Cu correlacionou-se fracamente com as características biológicas, exceto para o qCO2, o qual se mostrou promissor como indicador da contaminação com esses metais. Os dados indicaram uma interação qu

  7. Comparative study of three different kinds of geo membranes (PVC-P, HDPE, EPDM) used in the waterproofing of reservoirs; Estudio comparativo de tres geomembranas de distinta naturaleza (PVC-P, PEAD, EPDM) empleadas en la impermeabilizacion de balsas

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Fernandez, M.; Castillo Rubi, F.; Soriano Carrillo, J.; Noval Arango, A. M.; Touze-Foltz, N.; Pargada Iglesias, L.; Rico Arnaiz, G.; Aguilar gonzalez, E.

    2014-02-01

    This work describes the long-term behaviour of three kinds of geo membranes which are constituted by plasticised poly vinyl chloride (PVC-P), high density polyethylene (HDPE) and terpolymer rubber of ethylene-propylene-dienic monomer (EPDM) used as the waterproofing system of the reservoirs Los Llanos de Mesa, San Isidro and El Golfo, respectively. Characteristics of the three original geo membranes and their behaviour along time are presented. Thicknesses, content and nature of the plasticizers ( in PVC-P), tensile properties dynamic and static puncture, fold ability at low temperature, shore hardness, tear resistance and carbon black ( in HDPE), joint strength (shear and peeling test) and microscopy, both optical and electronic scanning tests were carried out. Results obtained conclude with a long-term durability of geo membranes, independently of their macromolecular nature. These characteristics were determined by advanced analytical techniques in PVC-P samples, such as fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography (GC) and Mass Spectrometry (MS). Spectrometry (MS). (Author)

  8. Studio di approfondimento sullo stato di salute nei Comuni dell'Alta Val di Cecina

    OpenAIRE

    Romanelli, Anna Maria; Bartolacci, Simone; Capocchi, Rachele; Mariani, Silvia; Minichilli, Fabrizio; Protti, Maria Angela; Salvadori, Patrizia; Tacconi, Giorgia; Vigotti, Maria Angela; Bianchi, Fabrizio

    2009-01-01

    Uno studio preliminare sull'Alta Val di Cecina, AVC, (Pisa) aveva evidenziato che tra le cause di morte, 1970-2004, alcune avevano un impatto pi? elevato o in controtendenza rispetto alla media regionale toscana; l'area presenta un sottosuolo geologicamente attivo, industrie chimiche, di produzione di energia, estrattive, documentate contaminazioni di acqua e suolo da metalli pesanti. Si segnalano eccessi di mortalit? e/o di ospedalizzazione per alcune patologie per le quali in letteratura ri...

  9. Inbreeding incidence on biological fitness in an isolated Mediterranean population: La Alta Alpujarra Oriental (Southeastern Spain)

    OpenAIRE

    Luna, Francisco; Valls, A.; Fernández Santander, Ana

    1998-01-01

    The incidence of parental inbreeding on biological fitness was analysed in a sample of the Alpujarrenian population. Fitness was estimated as the fertility and offspring viability from conception to reproductive age. The analysed sample represents about 45% of the population from the Alta Alpujarra Oriental in southeastern Spain, and includes 847 families and 2916 pregnancies. The results showed slightly higher reproduction in consanguineous marriages, but the differences observed were not st...

  10. Procesos de automatización cognitiva en alumnado con altas capacidades intelectuales

    Directory of Open Access Journals (Sweden)

    Juan Montero-Linares

    2013-05-01

    Full Text Available Proponemos desde el enfoque del procesamiento de la información, el estudio de características cognitivas que faciliten la identificación de las altas capacidades. A tal fin, elaboramos una tarea de habilidad de segmentación silábica que, a partir del modelo propuesto por Baddeley sobre la memoria de trabajo y la distinción entre procesos automáticos y controlados, nos permitiese comprobar las diferencias en cuanto a la capacidad de automatización de la información y si los indicadores propuestos en la misma, tenían suficiente poder clasificatorio o predictivo en la identificación de la alta capacidad intelectual. Participaron 480 niños y niñas de primero a cuarto de Educación Primaria. Se clasificaron, en función de su CI, en dos grupos: alumnado de altas capacidades y alumnado de capacidades medias. Se les administró una batería de pruebas entre las que se encontraba el test de habilidad de segmentación silábica, lo que permitió realizar su estandarización. Los resultados mostraron que los alumnos con CI superior a 130 fueron capaces de automatizar la segmentación de forma más eficiente que los de inteligencia media. La medición de los procesos automáticos a través del test de habilidad de segmentación silábica, permitió diferenciar a los participantes de altas capacidades de los que no lo eran.

  11. Neurossífilis resistente a altas doses de penicilina: registro de um caso

    Directory of Open Access Journals (Sweden)

    Ricardo Nitrini

    1984-03-01

    Full Text Available É relatado caso de paciente com neurossífilis que apresentou deterioração clínica e persistência de alterações do líquido cefalorraqueano após repetidas tentativas terapêuticas com altas doses de penicilina. Tratamento com cloranfenicol resultou em estabilização do quadro clínico e melhora laboratorial.

  12. Vital Signs – Presión arterial alta (High Blood Pressure)

    Centers for Disease Control (CDC) Podcasts

    2012-10-02

    En los EE. UU. casi un tercio de la población adulta tiene presión arterial alta, el principal factor de riesgo de enfermedades cardiacas y accidentes cerebrovasculares, dos de las principales causas de muerte en el país.  Created: 10/2/2012 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 10/17/2012.

  13. Basic specific gravity and anatomy of Peltophorum dubium wood as a function of provenance and radial position. Densidade aparente e anatomia da madeira de Peltophorum dubium em função da procedência e posição radial.

    Directory of Open Access Journals (Sweden)

    Israel Luiz de LIMA

    2015-06-01

    da madeira em comparação com as características externas mais sensíveis a estresses ambientais, como as folhas. Com base na literatura e em nossos resultados anteriores, a variação radial em P. dubium foi semelhante à encontrada em muitas espécies nativas, incluindo, por exemplo, aumento na densidade aparente, comprimento e espessura da parede das fibras, aumento no diâmetro e diminuição na frequência de vasos na direção da casca. Concluímos que P. dubium tem alta adaptabilidade em diferentes locais e que a consistência na qualidade de sua madeira pode ser mantida entre procedências, com implicações concomitantes, tanto para produção quanto para a utilização.

  14. Avaliação de germoplasma de camomila e densidade de semeadura na produção e composição do óleo essencial Evaluation of germplasm and seeding rate over the production and composition of chamomile essential oil

    Directory of Open Access Journals (Sweden)

    Wanderlei do Amaral

    2012-06-01

    Full Text Available O cultivo de camomila na região Sul do Brasil tem sido realizado utilizando-se como material genético a cultivar Mandirituba. Apesar da produção de capítulos florais e teor de óleos essenciais apresentado por esta cultivar ser considerado satisfatório, tem sido observada nas regiões produtoras a ocorrência de problemas fitossanitários que resultam em perdas significativas da produção. Este trabalho teve como objetivos comparar materiais genéticos de camomila provenientes da Holanda, Dinamarca e Mandirituba, e avaliar o efeito de diferentes densidades de semeadura no desenvolvimento das plantas, produção de capítulos, rendimento e qualidade do óleo essencial da cultivar Mandirituba, atualmente cultivada na região. Os experimentos foram conduzidos no município de Piraquara (PR. A extração do óleo essencial foi realizada por hidrodestilação em aparelho tipo Clevenger e a determinação da composição do óleo foi feita por cromatografia em fase gasosa acoplada ao espectrômetro de massa (GC/MS. Os materiais genéticos provenientes da Holanda e de Mandirituba apresentaram maior produção de biomassa seca de capítulos, em relação ao material genético da Dinamarca. A cultivar Mandirituba apresentou o maior rendimento de óleo essencial (4,71 mL g-1 ms, sendo também superior em relação à produtividade de óleo essencial (2,40 L ha-1. Os materiais procedentes da Dinamarca e de Mandirituba apresentaram composição do óleo essencial semelhantes. A densidade de plantio de 1,0 kg ha-1 da cultivar Mandirituba resultou em melhor desenvolvimento das plantas e maior produção de óleo essencial. Quantidades superiores a 3,0 kg ha-1 de sementes não resultaram em maior densidade de plantas tendo em vista a alta competição e percentual de plântulas mortas.The cultivar Mandirituba is the only genetic material for chamomile cultivation in southern Brazil. Besides the limitations regarding floral buds and the yield of

  15. Funcionalización de polietileno de baja densidad con anhídrido maleico en estado fundido

    Directory of Open Access Journals (Sweden)

    Manuel Guzmán

    2014-01-01

    Full Text Available En este estudio, polietileno de baja densidad (PEBD fue modificado con anhídrido maleico (AM en estado fundido usando concentraciones diferentes de peróxido de dicumilo (DCP (0.25, 0.50, 0.75 y 1.0 %. Los materiales obtenidos fueron caracterizados por contenido de gel, titulaciones ácido-base, análisis infrarrojo (IR, calorimetría de barrido diferencial (DSC, análisis termogravimétrico (TGA, análisis reológico, propiedades mecánicas, dureza y permeabilidad al oxígeno. El análisis reométrico indicó que el tiempo óptimo para obtener las mezclas es alrededor de 7.5 minutos. El análisis IR mostró que el AM fue injertado en el esqueleto del PEBD, el grado de injerto incrementó con el contenido de DCP y el más alto grado de injerto (1.12 ± 0.015 %, fue exhibido por la muestra obtenida empleando la mayor cantidad de DCP (1 %. La estabilidad térmica de las muestras funcionalizadas fue ligeramente mayor que la del PEBD. La cristalinidad de las muestras funcionalizadas fue diferente a la exhibida por el PEBD. El comportamiento reológico presentado por las muestras fue seudoplástico. Las propiedades mecánicas, dureza y la permeabilidad al oxigeno fueron dependientes de la cantidad de DCP y AM injertado en el PEBD.

  16. ESTRUTURA E POTENCIAL FUTURO DE UTILIZAÇÃO DA REGENERAÇÃO NATURAL DE FLORESTA DE VÁRZEA ALTA NO MUNICÍPIO DE AFUÁ, ESTADO DO PARÁ

    Directory of Open Access Journals (Sweden)

    José Roberto Soares Scolforo

    2003-05-01

    Full Text Available O presente estudo teve como objetivo analisar a estrutura e indicar as probabilidade de utilização futura da regeneração natural de uma floresta não-explorada de várzea alta localizada no município de Afuá (0° 09’ 24” S e 50° 23’ 12” W, ao norte do estado do Pará. Foram amostradas 29 subparcelas de 100 m2 nas quais se mediu a altura (h de árvores e palmeiras com h  0,30 m até o diâmetro a 1,30 m do nível do solo (DAP  15 cm, e o diâmetro das árvores compreendidas entre h  3,0 m até DAP  15 cm. A densidade total foi 30.969 indivíduos/ha, pertencentes a setenta espécies, 57 gêneros e 25 famílias botânicas, com índice de diversidade de Shannon (H’ de 2,68. As espécies mais importantes foram: Virola surinamensis, Euterpe oleracea, Astrocaryum murumuru, Geonoma laxiflora e Guarea guidonia. Muitas espécies são utilizadas como alimento pela fauna local, além de servirem como fonte de madeira e/ou, de produtos florestais não-madeireiros; algumas destas funcionam como complementação à dieta alimentar dos ribeirinhos, tais como: Eschweilera coriacea, Gustavia augusta, Inga Alba, Nectandra cf. risi e Protium spruceanum.

  17. Caracterització microestructural i mecànica de compòsits hdpe/fibres lignocel.lulòsiques

    OpenAIRE

    Colom Fajula, Xavier

    1999-01-01

    A partir de polietilè d'alta densitat i de fibres lignocel·lulòsiques provinents del trèmol (Populus tremula) s'han obtingut uns materials amb propietats úniques denominats compòsits. Aquests compòsits, amb un màxim de 40% de fibres lignocel·lulòsiques han estat tractats i modificats amb diferents agents (silà A-174 i epolè C-18) per millorar la compatibilitat entre la matriu de polietilè i el reforç fibrós. En una primera etapa les fibres lignocel·lulòsiques han estat pretractades amb cada u...

  18. Anestesia espinal alta para mastoplastia reductora. Experiencia de tres años

    Directory of Open Access Journals (Sweden)

    Néstor Parets Correa

    2012-05-01

    Full Text Available Fundamento: la aplicación de anestesia neuroaxial espinal alta en las intervenciones quirúrgicas resulta un tema controversial. Objetivo: describir los resultados de la aplicación de anestesia neuroaxial espinal alta en intervenciones quirúrgicas para mastoplastia reductora. Métodos: estudio descriptivo realizado en el Hospital General Universitario Dr. Gustavo Aldereguía Lima, de Cienfuegos, desde junio de 2006 hasta junio de 2009, que incluyó 90 pacientes operadas, en las cuales se empleó anestesia neuroaxial espinal alta. Se analizaron las variables: edad, índice de masa corporal, saturación de HBO2, tensión arterial, frecuencia cardiaca, uso de analgesia preventiva, comportamiento de la  analgesia posoperatoria, estado de satisfacción, presencia de complicaciones, técnica quirúrgica, duración del acto quirúrgico y de la anestesia. Resultados: el 50 % tenía  entre 35 y 44 años; 46, 7 % estaban sobrepeso; el 80 % se operó de hipertrofia mamaria; en el 97, 8 % se utilizó la mastopalstia reductora; ninguna presentó cifras altas de tensión arterial antes ni después de la aplicación de la anestesia, el 41,1 % presentó cifras bajas de tensión arterial después de la anestesia; la frecuencia cardiaca estuvo baja en el 31, 1 % después de aplicada la anestesia y alta en el 4, 4 %. La analgesia posoperatoria fue buena en el 87, 8 % de las pacientes; no hubo compromiso ventilatorio en ningún caso y el 100 % mostró satisfacción con la técnica anestésica. Conclusiones: la aplicación de la técnica anestésica permite desarrollar exitosamente las intervenciones quirúrgicas con un mínimo de riesgos y complicaciones para las pacientes.

  19. Rural Electrification of Coban Municipality, Alta Verapaz Department (Guatemala) using Intigis Model; Electrificacion Rural en el Municipio de Coban, Departamento de Alta Verapaz (Guatemala) segun el Modelo Intigis

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez Bravo, J.; Pinedo Pascua, I.; Auger Campos, C.; Cedillo Heine, A.; Gil Garcia, M.

    2009-05-15

    The present project started as an educational exercise for the Renewable Energies and Environment Masters given by the Polytechnic University of Madrid (UPM). It has been developed in collaboration with the research centre CIEMAT, the NGO Energy without Borders (ESF) and the University UPM, with the purpose of analyzing in a real context the application of Geographic Information Systems in renewable energies regional integration. The final aim of our study is to provide the isolated communities, specifically 13 communities in Alta Verapaz (Department of Coban, Guatemala), with the necessary conditions of electrification. This improvement will make possible the sustainable development of the area. Through the analysis of the geographic, technical and economic information gathered, using the IntiGIS methodology we will identify which is the most suitable autonomous generating system to cover the basic needs of the rural population in these Guatemalan communities. (Author) 9 refs.

  20. Alta miopia

    OpenAIRE

    Neves, Ana Raquel Borges

    2012-01-01

    O presente conjunto de apontamentos surge no âmbito de um estágio observacional realizado na Clínica Leite & Leite, em Lisboa, no decorrer do 2º ano do Mestrado em Optometria em Ciências da Visão. Neste relatório é relatada uma descrição do local onde se realizou o estágio, na qual constam todas as informações do percurso que qualquer paciente terá dentro da clínica em questão. De referir que, durante o tempo de estágio, foram observados 179 pacientes com diversas patologias, dados que pos...

  1. Plant densities of Urochloa decumbens in coexistence with Corymbia citriodoraDensidades de plantas de Urochloa decumbens em convivência com Corymbia citriodora

    Directory of Open Access Journals (Sweden)

    Jose Iran Cardoso Silva

    2011-12-01

    Full Text Available This study aimed to evaluate the effects of plant densities of Urochloa decumbens on the early growth of Corymbia citriodora. The experimental design was completely randomized design with four replications, each plot consisted of a of 60 L capacity vase. The signal grass densities were 0, 20, 40, 80 and 160 plants m-2, along with one eucalyptus plant. At the end of eight months of living together increase in height and in diameter and plant dry mass of eucalyptus and signal grass were carried out. The eucalyptus characteristics were influenced by all the weed populations, the effect being more pronounced with the increasing of grass density.O presente estudo teve como objetivo avaliar os efeitos da convivência de densidades crescentes de plantas Urochloa decumbens no crescimento inicial de plantas de Corymbia citriodora. O delineamento experimental adotado foi inteiramente casualisado, com quatro repetições; cada parcela constou de um vaso de 60 L de capacidade. As densidades de capim-braquiária foram: 0, 20, 40, 80 e 160 plantas m-2, juntamente com uma planta de eucalipto. Foram realizadas, ao final de oito meses de convivência, as avaliações de: incremento em altura e em diâmetro e massa seca das plantas de eucalipto e de capimbraquiária. Para todas as características estudadas a população infestante influenciou no desenvolvimento das plantas de eucalipto, sendo o efeito mais acentuado à medida que se aumentou a densidade de plantas de capim-braquiária.

  2. Estabilidad fenotípica y densidades de planta de genotipos de estevia (Stevia rebaudiana Bert. en la región Caribe de Colombia

    Directory of Open Access Journals (Sweden)

    Jarma Orozco Alfredo

    2011-06-01

    Full Text Available Los estudios de estabilidad fenotípica son importantes para la siembra de genotipos que muestranun adecuado comportamiento en una o varias zonas. Estevia (Stevia rebaudiana Bert. es una especierecientemente introducida en Colombia, por tanto, los estudios sobre su adaptación en áreas productorasdel país son escasos. Esta planta se caracteriza por sintetizar glucósidos de diterpeno altamenteedulcorantes con bajo aporte calórico. El presente estudio se realizó en Montería (8º 52' N y 76º 48'O, Colombia, con el objeto de determinar la estabilidad fenotípica de los genotipos Morita 1 y Morita 2de estevia, sembrados en tres densidades de plantas (25, 12.5 y 6.25 plantas/m2 y dispuestos en undiseño de bloques completos al azar, en tres épocas de siembra en el Caribe húmedo de Colombia. Losresultados más importantes señalan que Morita 2, en densidades de 25 plantas/m2, registró los mejoresíndices de estabilidad para el rendimiento de hoja seca/ha (Pig = 0; Pid = 0. Por su parte, éste mismogenotipo presentó una mayor relación hoja/tallo (1.17 ± 0.3 y mayor contenido de glucósidos totales(0.1586 ± 0.024 cuando la radiación solar fue mayor y las densidades eran entre 12.5 y 25 plantas/m2.

  3. Densidade e tamanho de formigueiros de Acromyrmex crassispinus em plantios de Pinus taeda Density and size of Acromyrmex crassispinus nests in Pinus taeda plantations

    Directory of Open Access Journals (Sweden)

    Mariane Aparecida Nickele

    2009-04-01

    Full Text Available O objetivo deste trabalho foi avaliar a densidade e o tamanho dos formigueiros de Acromyrmex crassispinus, ao longo do ano, em plantios de Pinus taeda de diferentes idades. Os experimentos foram realizados, em Rio Negrinho e em Três Barras, SC, em talhões de P. taeda com diferentes idades (recém-plantado, três anos e seis anos de idade. Em cada tratamento, foram demarcadas três parcelas de 1 ha. Os formigueiros foram classificados em três classes de tamanho: classe I, até 30 cm de diâmetro; classe II, 31 a 60 cm; e classe III, mais que 61 cm. A densidade de formigueiros de A. crassispinus foi menor no início do desenvolvimento da floresta, praticamente duplicou nos plantios com três anos, e reduziu quando a floresta estava com seis anos. A maior densidade de formigueiros ocorreu no período de dezembro a abril. Os formigueiros aumentaram de tamanho com a idade do pínus.The objective of this work was to evaluate the density and size of Acromyrmex crassispinus nests in Pinus taeda plantations along the year. The experiments were carried out in Rio Negrinho and Três Barras, SC, Brazil, in P. taeda plantations of different ages (recently planted and three and six years old. Three plots of one hectare were delimited in each treatment. The nests were classified according to three size classes: class I, up to 30 cm diameter; class II, 31 up to 60 cm; class III, above 61 cm. The density of A. crassispinus nests was low in recently planted areas, nearly twofold in three year-old plantations, and it reduced when the forest was six years old. The greatest nest density occurred in the period from December to April. The nests size increased along with the age of the P. taeda plantations.

  4. Estabilidad fenotípica y densidades de planta de genotipos de estevia (Stevia rebaudiana Bert. en la región Caribe de Colombia

    Directory of Open Access Journals (Sweden)

    Alfredo Jarma Orozco

    2011-04-01

    Full Text Available Los estudios de estabilidad fenotípica son importantes para la siembra de genotipos que muestran un adecuado comportamiento en una o varias zonas. Estevia (Stevia rebaudiana Bert. es una especie recientemente introducida en Colombia, por tanto, los estudios sobre su adaptación en áreas productoras del país son escasos. Esta planta se caracteriza por sintetizar glucósidos de diterpeno altamente edulcorantes con bajo aporte calórico. El presente estudio se realizó en Montería (8° 52' N y 76° 48' O, Colombia, con el objeto de determinar la estabilidad fenotípica de los genotipos Morita 1 y Morita 2 de estevia, sembrados en tres densidades de plantas (25, 12.5 y 6.25 plantas/m² y dispuestos en un diseño de bloques completos al azar, en tres épocas de siembra en el Caribe húmedo de Colombia. Los resultados más importantes señalan que Morita 2, en densidades de 25 plantas/m², registró los mejores índices de estabilidad para el rendimiento de hoja seca/ha (Pig = 0; Pid = 0. Por su parte, éste mismo genotipo presentó una mayor relación hoja/tallo (1.17 ± 0.3 y mayor contenido de glucósidos totales (0.1586 ± 0.024 cuando la radiación solar fue mayor y las densidades eran entre 12.5 y 25 plantas/m².

  5. Lipoproteínas de baja densidad y remanentes: diferentes mecanismos de oxidación y aterogénesis

    Directory of Open Access Journals (Sweden)

    Regina Wigdorovitz de Wikinski

    2010-12-01

    Full Text Available Las lipoproteínas de baja densidad oxidadas (LDLOX son factores cruciales en los mecanismos aterogénicos. Las LDL nativas y LDL pequeñas, densas, pasan al subendotelio por injuria endotelial, se oxidan en el subendotelio por efecto de radicales libres de oxígeno o disminución en la biodisponibilidad de óxido nítrico. Las LDLOX tienen propiedades quimiotácticas sobre los monocitos residentes, los cuales derivan de los monocitos circulantes que migraron al subendotelio con la cooperación de moléculas de adhesión. Las LDLOX se depositan en monocitos residentes/ macrófagos, formando células espumosas que evolucionan a estrías grasas y ateromas. En las lesiones no se encuentran LDL nativas, sino LDLOX que estimulan la esterificación del colesterol y son degradadas por macrófagos. Las lipoproteínas de muy baja densidad (VLDL y los quilomicrones son precursoras de las lipoproteínas de densidad intermedia (IDL y de los remanentes (QR, respectivamente. El conjunto de IDL y QR forma las lipoproteínas remanentes (RLP. Su papel aterogénico es atribuible a su oxidabilidad en plasma y en células endoteliales. Las RLP se oxidan en receptores específicos de las células endoteliales, que son dañadas por liberación de citoquinas, inflamación y apoptosis celular. En el subendotelio son captadas por células espumosas y se depositan en ateromas. Su efecto aterogénico está potenciado por los ácidos grasos libres, que dañan al endotelio.

  6. EFECTO DE LA DENSIDAD DE SIEMBRA Y DEL APORQUE EN LA PRODUCCIÓN Y CALIDAD DE LA CEBOLLA PUERRO (Allium ampeloprasum L. var. porrum J. Gay

    Directory of Open Access Journals (Sweden)

    Fernando Javier Peña Baracaldo

    2015-06-01

    Full Text Available La cebolla puerro y otras liliáceas, tradicionalmente, se han localizado en valles de climas medios y fríos moderados de las regiones andinas y cercanos a los centros de consumo. La producción y consumo de Allium ampeloprasum L. var. porrum J. Gay, se ha incrementado por sus cualidades condimentarias y por los beneficios de carácter medicinal. Los sistemas productivos implementados para esta hortaliza adoptan tecnologías procedentes de países con condiciones diferentes a las nuestras. Por lo tanto, para optimizar el cultivo y satisfacer la demanda creciente de mercados especializados, se requiere evaluar prácticas agronómicas, lo cual, se constituyó en el propósito del presente trabajo. Se determinó el efecto de cinco densidades de siembra y del aporque, sobre el peso, el diámetro y la longitud del tallo. Los resultados mostraron que a mayor densidad, el peso y el diámetro del fuste disminuyeron, sin ser afectadas por el aporque, mientras que la longitud de pseudotallo presentó una relación directamente proporcional: a mayor densidad, mayor longitud. Se obtuvieron puerros con longitudes superiores a la media del mercado, con las distancias de 20 x 25cm y 30 x 25cm, en donde también se lograron los mayores pesos frescos promedios, 354,93g y 354,42g, respectivamente. A una distancia de siembra de 30cm x 5cm, se cosecharon puerros largos y delgados. La práctica del aporque es necesaria dentro del sistema de producción de la cebolla puerro para el blanqueado del tallo; sin embargo, dicha práctica no influyó directamente sobre los parámetros de producción, como el peso y el diámetro del pseudotallo.

  7. GÉNEROS BACTERIANOS DOMINANTES EN LOS ESTRATOS FOLIARES DEL TABACO CURADO PARA CAPAS. INFLUENCIA DE LA NICOTINA Y EL pH SOBRE SU DENSIDAD POBLACIONAL

    Directory of Open Access Journals (Sweden)

    Yunior M. Morán Gómez

    2013-01-01

    Full Text Available Aunque las bacterias juegan un papel importante en el proceso fermentativo del tabaco, en Cuba no se han identificado los géneros presentes en el tabaco curado para capas, ni las variables que afectan a sus poblaciones. Este conocimiento pudiera contribuir al manejo de los procesos en los que estos microorganismos intervienen. El objetivo de esta investigación fue determinar la relación que existe entre la densidad poblacional de los géneros bacterianos dominantes en los diferentes estratos foliares de la planta de tabaco luego de la curación y la concentración de nicotina y los valores de pH en estos ambientes. Se realizó el aislamiento e identificación genérica de la microbiota bacteriana y se determinó el contenido de nicotina y el pH de las hojas de tabaco para cada estrato foliar. Las poblaciones de Bacillus en todos los estratos foliares siempre fueron superiores a otros géneros aislados como Staphylococcus y Arthrobacter . Desde los niveles foliares inferiores hasta los superiores el contenido de nicotina se incrementó significativamente, el pH mostró una ligera disminución (no significativa p<0,01 y disminuyó la densidad poblacional de bacterias de todos los géneros aislados. El modelo de regresión reveló que la disminución de la densidad poblacional de los géneros bacterianos que se aprecia al ascender por los diferentes niveles foliares estuvo más relacionada con el incremento de la concentración de nicotina en las hojas que con la variación del pH.

  8. Densidad mineral ósea y adecuación de la dieta en pacientes con enfermedad renal crónica en hemodiálisis

    OpenAIRE

    Fernando Carrasco; Marcelo Cano; Jean Camousseigt; Pamela Rojas; Jorge Inostroza; Rubén Torres

    2013-01-01

    Introducción: La desnutrición es común en la enfermedad renal crónica (ERC), junto a una menor masa muscular y densidad mineral ósea (DMO), aumentando el riesgo de morbilidad. Objetivo: Comparar la composición corporal (CC), DMO y el contenido mineral óseo (CMO) entre pacientes con ERC y sujetos sanos, relacionándolos con ingesta energética, de macro y micronutrientes. Métodos: Se evaluó CC en 30 pacientes en hemodiálisis y 28 voluntarios sanos con DEXA. Los pacientes llenaron tres registros ...

  9. Densidad poblacional de la codorniz Moctezuma (Cyrtonyx montezumae) en la región noroeste del Estado de México, México

    OpenAIRE

    Jaime Tapia Robles; Salvador Ibarra Zimbrón; Germán David Mendoza Martínez; Cecilia Zaragoza Hernández; Fernando Clemente Sánchez; Luis Antonio Tarango Arámbula

    2002-01-01

    El presente estudio se realizó para determinar la densidad poblacional de la codorniz Moctezuma ( Cyrtonyx montezumae) en la región noroeste del Estado de México, México. El área de estudio correspondió a la región cinegética II del calendario cinegético 1997, con un marco de muestreo de 249 700 ha, 73% forestal y 27% pastizales, mismos que fueron considerados como estratos. Se realizó un muestreo en 22 unidades, en las cuales se realizaron transectos de 5 km de longitud por 50 m ...

  10. Estudio de la adaptabilidad de cuatro genotipos de guisante (pisum setivum l. var. macrocarpon) bajo dos densidades y en dos localidades

    OpenAIRE

    Aguilar, Miguel; Brusco, Patricia; Martínez, Ricardo

    2011-01-01

    Se evaluó y comparó el comportamiento agronómico de cuatro variedades de guisante Pisum satim L. var. macrocarpon bajo dos densidades y en dos localidadesmediante cultivos a libre exposición durante dos semestres. Se midieron variables de tipo morfofisiológico y reproductivo. Las cuatro variedades se adaptaron bien al medio ambiente ya que sus rendimientos fueron bastante aceptables. La variedad Super Mel Sugar logró los mejores puntajesen rendimiento y calidad además de la mayor capacidad de...

  11. Fabricación y comportamiento de espumas de aluminio con diferente densidad a partir de un precursor AlSi12

    Directory of Open Access Journals (Sweden)

    Gutiérrez-Vázquez, J. A.

    2010-06-01

    Full Text Available Closed cell aluminium foams were prepared by powder metallurgical method in three different ranges of density using AlSi12 precursor. The objective has been to determine by means of tests the effect that has the density of these materials regarding its mechanical behaviour. The used precursor contained 0.4% of foaming agent of titanium hydride (TiH2, mixed with aluminum and silicon in appropriate amounts to achieve the commercial composition of the AlSi12 precursor. Once cut the samples thermal treatments of foaming were made of 630 °C to 750 °C, by 3 to 20 minutes. The best solidification conditions were determined to avoid the collapse by means of forced air. The samples were prepared with the same weight to different densities, having itself obtained that the best mechanical behaviour was achieved in the high density foams, of 0.70 to 0.81 g/cm3.

    Se han fabricado espumas de aluminio de poro cerrado, de tres diferentes rangos de densidad, utilizando un precursor AlSi12 producido por pulvimetalurgia. El objetivo ha sido determinar el efecto que tiene la densidad de estos materiales respecto a su comportamiento mecánico. El precursor utilizado contenía un 0,4 % de hidruro de titanio (TiH2 como agente espumante, mezclado con aluminio y silicio en cantidades adecuadas para lograr la composición comercial del precursor AlSi12. Una vez cortadas las muestras, se efectuaron tratamientos térmicos de espumación entre 630 y 750 °C, a tiempos de espumación variables entre 3 y 20 min. Se determinaron las mejores condiciones de solidificación para evitar el colapso mediante aire forzado. Las muestras se prepararon con el mismo peso a diferentes densidades, habiéndose obtenido, que el mejor comportamiento mecánico se lograba en las espumas de mayor densidad, comprendidas entre 0,70 y 0,81 g/cm3.

  12. DENSIDAD DE PALOMA DOMÉSTICA (Columbia livia domestica GMELIN, 1789) EN EL NUEVO MERCADO PÚBLICO DE SINCELEJO, SUCRE, COLOMBIA

    OpenAIRE

    Carmen Villalba-Sánchez; Alejandro De La Ossa-Lacayo; Jaime De La Ossa V

    2015-01-01

    El presente trabajo determinó la densidad poblacional de Columba livia domestica en el nuevo mercado de la ciudad de Sincelejo, Sucre, Colombia. Se conoce que cuando las poblaciones de esta especie se incrementan desmedidamente, se convierte en un serio problema de salud pública, que debe ser atendido, para evitar la transmisión de enfermedades zoonóticas. En Sincelejo, especialmente en la zona de estudio, se tenía desconocimiento de la magnitud de su población, al igual que sucede para mucha...

  13. Evolución del peso, densidad mineral ósea y metabolismo lipídico en el paciente trasplantado renal.

    OpenAIRE

    Fernández-Castillo, Rafael

    2015-01-01

    [ES]Tras el trasplante se producen una serie de alteraciones metabólicas que podrían llegar a poner en riesgo la supervivencia del injerto y comprometer seriamente el estado de salud del paciente trasplantado renal. Entre las complicaciones metabólicas mas importantes se encuentran las alteraciones del metabolismo mineral y óseo y las alteraciones del metabolismo lipídico. Este trabajo tiene como objetivo investigar la ganancia de peso, las modificaciones en la densidad mineral ósea y la hip...

  14. Larvicultura do Mandi-amarelo Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae) em Diferentes Densidades de Estocagem nos Primeiros Dias de Vida

    OpenAIRE

    Luz Ronald Kennedy; Zaniboni Filho Evoy

    2002-01-01

    Este trabalho foi realizado na Estação de Piscicultura de São Carlos (EPISCar), São Carlos, SC. O efeito da densidade de estocagem de Pimelodus maculatus na larvicultura foi avaliado em pós-larvas alimentadas diariamente com zooplâncton selvagem na proporção de 300 organismos/pós-larva/dia e submetidas aos seguintes tratamentos: T1 - 5 pós-larvas/litro; T2 - 15 pós-larvas/litro; T3 - 30 pós-larvas/litro. No terceiro e quinto dias de experimento, foi avaliada a taxa de sobrevivência. Decorrido...

  15. Património e turismo em áreas de baixas densidade : o caso das aldeias do Pessegueiro e do Esquio

    OpenAIRE

    Ventura, Marta Sofia Gomes

    2010-01-01

    Este trabalho apresenta uma reflexão sobre as trajectórias, dinâmicas e desenvolvimento das áreas rurais de montanha. A crescente valorização ambiental das áreas rurais trouxe novos dinamismos e potencialidades a estes espaços de baixas densidades. Outrora afectados por um intenso êxodo rural e por um paulatino e doloroso despovoamento e esquecimento, começam a ser redescobertos e a ganharem multifuncionalidades, vinculando-se a actividades lúdicas, desportivas ou terapêuticas. As áreas...

  16. Balance hídrico del suelo en pinares con diferente densidad de arbolado. Efectos sobre el establecimiento de brinzales de especies rebrotadoras bajo el dosel

    OpenAIRE

    Chirino Miranda, Esteban; Heredia-Osorio, Miriam; Granados, María Elena; Vilagrosa Carmona, Alberto; Manrique-Alba, Ángela; Ruiz-Yanetti, Samantha; Andarcio, Carlos; Bellot Abad, Juan Francisco

    2015-01-01

    El objetivo del presente trabajo fue determinar el balance hídrico del suelo en bosques de pino carrasco con diferente densidad de arbolado utilizando el modelo ecohidrológico HYDROBAL, y evaluar sus efectos sobre la introducción y establecimiento bajo el dosel, de brinzales de especies ampliamente utilizadas en la restauración forestal. En este contexto, en La Hunde (Ayora, Valencia), y como consecuencia de previas labores de aclareo con diferente intensidad, se definieron tres tratamientos ...

  17. Densidad ósea y frecuencias de hallazgos en restos humanos en el Norte de Tierra del Fuego: Análisis exploratorio

    OpenAIRE

    Suby, Jorge A.; Ricardo A. Guichón

    2004-01-01

    La disponibilidad del registro biológico humano para su estudio está condicionada por procesos paleoecológicos y tafonómicos. Vinculado con esta problemática interesa explorar la relación entre Densidad Mineral Ósea (DMO) y frecuencias relativas de restos óseos humanos en el norte de Tierra del Fuego. La determinación de DMO ha sido poco empleada para el estudio de restos óseos humanos arqueológicos. Se contrastó la información densitométrica de restos provenientes del sitio Las Mandíbulas (T...

  18. Densidade e tamanho de formigueiros de Acromyrmex crassispinus em plantios de Pinus taeda Density and size of Acromyrmex crassispinus nests in Pinus taeda plantations

    OpenAIRE

    Mariane Aparecida Nickele; Wilson Reis Filho; Edilson Batista Oliveira; Edson Tadeu Iede

    2009-01-01

    O objetivo deste trabalho foi avaliar a densidade e o tamanho dos formigueiros de Acromyrmex crassispinus, ao longo do ano, em plantios de Pinus taeda de diferentes idades. Os experimentos foram realizados, em Rio Negrinho e em Três Barras, SC, em talhões de P. taeda com diferentes idades (recém-plantado, três anos e seis anos de idade). Em cada tratamento, foram demarcadas três parcelas de 1 ha. Os formigueiros foram classificados em três classes de tamanho: classe I, até 30 cm de diâmetro; ...

  19. Evaluación forestal y de combustiblesen bosques de Pinus hartwegiien el Estado de México según densidades de cobertura y vulnerabilidad a incendios

    OpenAIRE

    Mario Fermin Castañeda Rojas; Angel Rolando Endara Agramont; María de Lourdes Villers Ruiz; Eufemio Gabino Nava Bernal

    2015-01-01

    En el presente estudio se hace una evaluación forestal asociada a la cantidad y calidad de combustibles muertos en bosques de P. hart-wegii para señalar condiciones de vulnerabilidad y propensión a incendios. Con interpretación de imágenes de satélite multiespectrales del 2010, se determinaron tres densidades de cobertura para 23 685 ha de bosque de P. hartwegii del Estado de México. Se realizó un inventario forestal, presencia de actividad humana, carga de combustibles y parámetros físicos e...

  20. LA DENSIDAD Y TAMAÑO DE PLÁNTULAS CON CEPELLÓN EN LA PRODUCCIÓN DE ESPÁRRAGO VERDE

    Directory of Open Access Journals (Sweden)

    Ana Mar\\u00EDa Castagnino

    2011-01-01

    Full Text Available Con el objetivo de determinar la influencia del tamaño de la celda utilizada para la obtención de plántulas de espárrago y la densidad o marco de plantación empleado, sobre la producción de turiones, se evaluó en invernadero tres tamaños de celda: 1 PG: grande (70 cm3, 2 PM: mediana (30 cm3 y 3 PCh: pequeña (20 cm3 y tres densidades (35 714 (D1; 23 810 (D2 y 17 857 (D3 plantas/ha. Se efectuó un trabajo en la Chacra Experimental de la Facultad de Agronomía, en Azul, provincia de Buenos Aires. La plantación en el campo se efectuó en noviembre 2002, setenta días después de la siembra del almácigo con plántulas con cepellón. La cosecha se realizó del 25/09 al 18/10 del año 2006, en el cuarto año desde la plantación, con una frecuencia de cosecha de día por medio. Se realizó un análisis de la varianza, con un diseño completamente al azar y considerando como factor: el tamaño de las plántulas que provenían de cada contenedor y tres densidades. En el segundo año evaluado, la densidad D1 fue la de mayor producción (4450 kg/ha netos totales y mayor cantidad de turiones (380 166. Las plantas provenientes de los dos mayores tamaños de celda produjeron 4 t/ha netas en promedio. Las bandejas de siembra de tamaño G y D1 resultaron más apropiados para la producción de espárrago ya que permitieron obtener el mayor rendimiento en peso y número, y obtener un mejor aparato radical.

  1. Densidade e diversidade fenotípica de bactérias diazotróficas endofíticas em solos de mineração de bauxita, em reabilitação Density and phenotypic diversity of endophytic nitrogen fixing bacteria in soils under rehabilitation after bauxite mining

    Directory of Open Access Journals (Sweden)

    R. Melloni

    2004-02-01

    Full Text Available Bactérias diazotróficas endofíticas contribuem para o desenvolvimento das plantas por meio da fixação biológica do nitrogênio, produção e liberação de substâncias reguladoras do crescimento vegetal, podendo, assim, facilitar a revegetação de solos degradados por atividades antrópicas. No entanto, pouco se conhece sobre as populações destas bactérias em solos ou plantas de áreas de mineração. Objetivando avaliar o efeito de diferentes tipos de vegetação e tempo de reabilitação de áreas degradadas por mineração de bauxita na densidade e diversidade de algumas espécies de bactérias diazotróficas endofíticas, realizaram-se, em duas épocas, amostragens de solo, de dois ambientes distintos, submetidos a diferentes processos de reabilitação. A densidade, avaliada pelo número mais provável, utilizando os meios de cultura: NFb, JNFb e Fam, para Azospirillum brasilense e A. lipoferum, Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0 a 2,0 x 10(4 bactérias por grama de solo e mostrou que o tipo de vegetação influiu nas populações destas bactérias. Foram encontradas densidades maiores em solos revegetados com gramíneas: braquiária (Brachiaria decumbens, capim-azevém (Lolium multiflorum e capim-gordura (Melinis minutiflora. Contudo, estas densidades podem ser consideradas baixas, se comparadas às de solos agrícolas, e não apresentaram relação com o tempo de reabilitação da área. Foram encontrados 36 fenótipos culturais em meio batata, entre os 72 isolados obtidos dos três meios de cultura utilizados. A partir destes, foram formados sete grandes grupos com similaridade superior ou igual a 63 %, dos quais cinco, representando 62,5 % do total de isolados obtidos, continham as estirpes-tipo de Burkholderia brasilensis, Herbaspirillum seropedicae e Azospirillum spp. (A. brasilense, A. amazonense, A. lipoferum, A. irakense. Apesar da baixa densidade, este grupo de bactérias apresentou alta

  2. Efeitos do treinamento resistido na lipoproteína de baixa densidade Effects of resistance training on low density lipoprotein

    Directory of Open Access Journals (Sweden)

    Jeferson Luis da Silva

    2010-02-01

    Full Text Available Os benefícios da prática regular do exercício físico estão claramente estabelecidos na literatura. Entretanto, a escolha do tipo de exercício ideal pode ser mais salutar para indivíduos com doenças específicas e patologias associadas. O propósito desta revisão foi verificar se o treinamento resistido (TR exerce alguma alteração no colesterol da lipoproteína de baixa densidade (LDL-C. Foram observadas grandes diferenças na literatura, dificultando uma conclusão em relação aos benefícios do TR nesta revisão. No entanto, foi visto que o TR pode ser promissor na redução dos níveis de LDL-C, principalmente em homens e mulheres adultos, em pacientes com diabetes mellitus tipo 1 e tipo 2 e em mulheres pré-menopausa, não mostrando diferenças na população idosa. Os autores concluem que o TR é uma boa opção de exercício físico para indivíduos, principalmente quando o treinamento aeróbio (TA é contraindicado.The benefits of exercise regular practice are clearly established in the literature. However, the choice of the ideal exercise may be more beneficial for individuals with specific diseases and associated pathologies. The aim of this review was to determine whether resistance training (RT promotes any change on low density lipoprotein cholesterol. Important differences were observed in research protocols, making it difficult to define the benefits of RT in this review. However, it was noticed that RT may be promising in reducing LDL-C levels mainly in adult men and women, in patients with diabetes mellitus type 1 and type 2 and in pre-menopausal women, not presenting differences in the elderly population. It was concluded that the RT is an option good of physical exercise for individuals, especially when the aerobic training (AT is contra-indicated.

  3. Densidade mineral óssea de adolescentes com sobrepeso e obesidade Bone mineral density in overweight and obese adolescents

    Directory of Open Access Journals (Sweden)

    Fernanda Cobayashi

    2005-08-01

    Full Text Available OBJETIVO: Estudar a densidade óssea como fator concomitante da obesidade em adolescentes pós-púberes, controlando outras variáveis que possam interferir nessa relação. MÉTODOS: Estudo com 83 sobrepesos e obesos (IMC > P85 e 89 não obesos (P5 OBJECTIVE: to study bone density as a concomitant factor for obesity in post-pubertal adolescents, controlling for other variables that may interfere in such a relation. METHODS: Study comprising 83 overweight and obese adolescents (BMI > P85 and 89 non obese ones (P5 < BMI < P85. Cases and controls were selected out of 1,420 students (aged 14-19 from a public school in the city of São Paulo. The bone mineral density of the lumbar spine (L2-L4 in g/cm² was assessed by dual-energy x-ray absorptiometry (LUNAR™ DPX-L. The variable bone density was dichotomized using 1.194 g/cm² as cutoff point. Bivariate analyses were conducted considering the prevalence of overweight and obesity followed by multivariate analysis (logistic regression according to a hierarchical conceptual model. RESULTS: The prevalence of bone density above the median was twice more frequent among cases (69.3% than among controls (32.1%. In the bivariate analysis such prevalence resulted in an odds ratio (OR of 4.78. The logistic regression model showed that the association between obesity and mineral density is yet more intense with an OR of 6.65 after the control of variables related to sedentary lifestyle and intake of milk and dairy products. CONCLUSION: Obese and overweight adolescents in the final stages of sexual maturity presented higher bone mineral density in relation to their normal-weight counterparts; however, cohort studies will be necessary to evaluate the influence of such characteristic on bone resistance in adulthood and, consequently, on the incidence of osteopenia and osteoporosis at older ages.

  4. Densidad de población de pequeños mamíferos en dos comunidades del bosque Andino Densidad de población de pequeños mamíferos en dos comunidades del bosque Andino

    Directory of Open Access Journals (Sweden)

    Rodríguez Jane Rose

    1988-06-01

    Full Text Available

    The density of small mammals living in two communities of the Andean Forest of the eastern slopes of the Sabana de Bogota in the western Cordillera (Cerro Cueva Grande and Cerro Majuy, was studied. The two places were tramped for six months between March and September 1981, using livetraps and snaptraps during six days per month in each community. Densities for each species were obtained by the Hayne Melbod, the Lincoin and Jolly Indexes and by absolute density. Flora, climate and soil characteristics and their influence in the species were also considered in the two communities.

    Se estudió la densidad de población de pequeños mamíferos en dos comunidades de Bosque Andino, Cerro Cueva Grande, en el flanco occidental de la Sabana de Bogotá y Cerro Majuy, en la Sabana, localizadas sobre la Cordillera Oriental. Los dos sitios fueron trampeados en un periodo de seis meses desde marzo hasta septiembre del año 1981, uti1izando trampas para captura de animales vivos y trampas de golpe durante seis días por mes en cada comunidad. Se obtuvieron densidades para cada especie por el método de Hayne, y los índices de Lincoln, de Jolly y de densidad absoluta. Se tuvieron en cuenta las características de flora, clima y suelo para las dos comunidades y la manera como influye en las especies estudiadas.

  5. El ferulado con caños de polietileno de baja densidad PBDE para agua en la reparación de las fracturas acrales

    OpenAIRE

    Baraboglia, E. R.

    2010-01-01

    ResumenDesde el principio de los tiempos se le ha presentado al hombre el problema de las fracturas traumáticas y es de imaginar que tal vez en tan o más alta proporción que ahora, dado el sistema rudo en que les tocaba vivir.

  6. Plan de alta para personas con enfermedad pulmonar obstructiva crónica

    Directory of Open Access Journals (Sweden)

    Luz Marina Céspedes Salgado

    2006-01-01

    Full Text Available El plan de alta busca asegurar unos cuidados acordes con las necesidades y los requerimientos de la persona una vez egresa de la institución de salud, y debe constituirse en una guía básica en especial para la atención de aquéllos con patologías crónicas, como es la enfermedad pulmonar obstructiva crónica, que por su complejidad demanda múltiples cuidados para asegurar una intervención integral con miras al logro de una mejor adaptación, a identificar posibles complicaciones y a mejorar su calidad de vida. La experiencia de haber asumido el rol de hija y enfermera de un padre con enfermedad pulmonar obstructiva crónica (EPOC, y la alta incidencia de esta enfermedad, motivaron la elaboración de este plan de alta; fueron muchos los cuidados y muchas las necesidades y los cuestionamientos que se daban día a día, desde asegurar una adecuada comunicación hasta un conocimiento de los signos y síntomas de urgencia que indicaban una exacerbación, del uso adecuado de los medicamentos, de la importancia de la oxigenoterapia a largo plazo, de proporcionarle una dieta acorde con las recomendaciones y un ambiente favorable para sus condiciones de salud para, en últimas, alcanzar un entorno armónico, físico, familiar y espiritual.

  7. Recubrimientos depositados por cvd-fbr para protección a alta temperatura

    OpenAIRE

    Jose Luddey Marulanda-Arevalo; Saul Castañeda-Quintana; Aduljay Remolina-Millan

    2013-01-01

    La deposición química de vapor por lecho fl uidizado (CVD-FBR) es una variante de la técnica de deposición química de vapor; que combina las ventajas de la activación térmica por calentamiento y el lecho fl uidizado. Los recubrimientos mediante CVD-FBR son ampliamente investigados y usados debido a la necesidad de proteger superfi cialmente los componentes que operan a altas temperaturas, el cual ha aumentado perceptiblemente. Además, tiene la ventaja de ser una técnica de bajo costo, puede c...

  8. Anticorpos policlonais em dietas com alta inclusão de concentrado para bovinos confinados

    OpenAIRE

    Danilo Domingues Millen; João Ricardo Ronchesel; Fernando Salvador Parra; Rodrigo Dias Lauritano Pacheco; Cyntia Ludovico Martins; Mário de Beni Arrigoni

    2013-01-01

    Dentre as alternativas para substituir o uso de ionóforos classificados como antibiótico por alguns comitês, a utilização de anticorpos policlonais classificados como promotores de crescimento naturais tem se mostrado alternativa interessante e economicamente eficiente. Recentes estudos demonstraram pontos positivos na utilização desse aditivo em dietas com alta inclusão de ingredientes concentrados para bovinos confinados, traduzido por melhora de desempenho e saúde ruminal, em alguns casos,...

  9. Contabilidad Financiera y Social de la Alta Velocidad en España

    OpenAIRE

    Ofelia Betancor; Gerard Llobet

    2015-01-01

    Este trabajo estudia la rentabilidad financiera y social de la alta velocidad ferroviaria en España. El análisis se realiza para los cuatro corredores en funcionamiento a finales de 2013. Ambos análisis son contrafactuales, es decir, toman como punto de referencia lo que habría sucedido en caso de no acometer estas inversiones. Asimismo ambos se realizan para un horizonte temporal de 50 años que nos lleva a utilizar como criterios de decisión el VAN financiero y social en términos de valor es...

  10. El entrenamiento interválico de alta intensidad para el rendimiento deportivo

    OpenAIRE

    Alvarez Fernández, Iker

    2014-01-01

    El entrenamiento interválico de alta intensidad (HIIT) ha sido una parte más de los programas de entrenamiento para mejorar el rendimiento deportivo, pero su efecto puntual en los entrenamientos de deportistas altamente entrenados no se conoce en su totalidad, a pesar de ser un elemento importante de la preparación deportiva. En esta revisión veremos cómo diversas investigaciones demuestran los diferentes efectos y adaptaciones que provoca el HIIT en estos deportistas con el fin de la mejora ...

  11. USO DE IMÁGENES SATELITALES DE ALTA RESOLUCIÓN PARA GENERAR CARTOGRAFÍA

    OpenAIRE

    Patricio Zavala; Carlos Zavala

    2002-01-01

    Se presenta la metodología aplicada en la ciudad de Arica, Norte de Chile, para generar cartografía de altura de construcciones, mediante el análisis digital de una imagen satelital de alta resolución. Para ello, nos basamos en el cálculo de la longitud de las sombras que se derivan de distintas edificaciones, y del azimut solar de una imagen IRS 1C, que fue remuestreada mediante convolución cúbica a 5 metros. Este trabajo está basado fundamentalmente en los logros alcanzados en el desarrollo...

  12. Ampliación de un generador de impulsos de alta tensión

    OpenAIRE

    Hernández Anguita, Iker

    2011-01-01

    El primer objetivo de este proyecto fin de carrera será hallar el valor de la capacidad del objeto de ensayo, en este caso un transformador de corriente de alta tensión con el bobinado secundario cortocircuitado a tierra. Se realizara la medición por distintos métodos para contrastar los resultados. Este valor de capacidad será necesario para el dimensionado de las resistencias de descarga del generador. Una vez obtenido el valor de la capacidad se procederá a la construcción de los nuevos el...

  13. La identificación de alumnos con altas habilidades: enfoques y dimensiones actuales

    OpenAIRE

    Rojo Martínez, Angela

    1996-01-01

    La tesis ha quedado estructurada en dos partes. En la primera, se desarrolla y fundamenta el marco teórico de este trabajo de investigación, desde el que se presentan los principales planteamientos conceptuales que han ayudado y están contribuyendo a definir la alta habilidad intelectual, haciendo especial hincapié en enfoques amplios y variados, que permitan que la identificación de esos sujetos se realice considerando junto a su potencial intelectual otras muchas y diferentes variables. Y l...

  14. CARCINOMA BRONQUÍOLO-ALVEOLAR: ASPECTOS NA TOMOGRAFIA COMPUTADORIZADA DE ALTA RESOLUÇÃO

    OpenAIRE

    Moreira Luiza Beatriz Melo; Marchiori Edson; Melo Alessandro Severo Alves de; Magnago Marcelo; Muniz Maria Angélica Soares; Irion Klaus

    2002-01-01

    O carcinoma bronquíolo-alveolar é um tipo de carcinoma broncogênico de crescimento insidioso, que surge nas paredes das vias aéreas distais e se dissemina utilizando o septo alveolar como um estroma, preservando a arquitetura pulmonar. Neste trabalho foram analisadas as tomografias computadorizadas de alta resolução de 17 pacientes com carcinoma bronquíolo-alveolar. Ao contrário do relatado na literatura, foram observados predomínio no sexo masculino (71%) e maior freqüência da associação das...

  15. Factores de riesgo que incrementan la morbimortalidad en pacientes con hemorragia digestiva alta

    OpenAIRE

    Rodríguez Hernández, Iyemai

    2011-01-01

    La Hemorragia digestiva alta (HDA) es una emergencia médico quirúrgica frecuente que presenta una elevada morbimortalidad, constituyendo la principal urgencia en gastroenterología. El cuidado de enfermería, como el conjunto de funciones fundamentadas en la relación interpersonal y en el dominio de lo técnico-científico orientada a comprender al otro en el entorno en el que se desenvuelve, interviene en una forma importante en la prevención, la curación y la rehabilitación de la persona en el ...

  16. Efeito de alta pressão no processo de demolha de bacalhau

    OpenAIRE

    Salvador, Ângelo Miguel Correia

    2009-01-01

    Este trabalho experimental teve como objectivo recorrer à tecnologia de alta pressão hidrostática com o intuito de acelerar o processo de demolha de bacalhau, em termos de saída de sal e entrada de água. Inicialmente tentou-se desenvolver uma metodologia rápida para quantificação do NaCl mediante condutivimetria. Contudo, como se verificaram diferenças entre os resultados obtidos por este método e o método químico usado neste trabalho, a quantificação do sal por condutivimet...

  17. Estudio del comportamiento en flexocompresión de los hormigones de alta resistencia

    OpenAIRE

    Arenas de Pablo, Juan José; Gutiérrez Martín, Germán; Vicente Cabrera, Miguel Ángel; González Cabrera, Dorys Carmen

    2004-01-01

    RESUMEN. Este artículo describe la máquina de ensayo desarrollada en el Laboratorio de Estructuras de la Universidad de Cantabria para obtener experimentalmente la distribución de tensiones en hormigones de diferentes resistencias, desde hormigones convencionales hasta hormigones de alta resistencia. Utilizando la máquina de ensayo anteriormente mencionada han sido ensayadas 240 probetas bajo carga creciente y excéntrica hasta rotura. Las variables de ensayo han sido la forma de la probeta, e...

  18. Determinación de aminas aromaticas por cromatografia liquida de alta resolución.

    OpenAIRE

    Gutiérrez Bouzán, Mª Carmen; Crespi Rosell, Martin

    1989-01-01

    Este trabajo consiste en la puesta a punto del metodo analítico para la determinación por cromatografia liquida de alta resolución (HPLC) de las aminas aromáticas empleadas más frecuentemente en la fabricación de colorantes sulfurosos: m-tolilendiamina, p-fenilendiamina, o-toluidina, p-toluidina, anilina, p-aminofenol, difenilamina, y p-hidroxidifenilamina. La longitud de onda de detección es de 260 nm. El principal objetivo del presente estudio es la consecución de un método de análisis p...

  19. Estudio del feedback docente de los entrenadores de tenis de alta competición

    OpenAIRE

    Fuentes García, Juan Pedro; García González, Luis; Sanz Rivas, David; Moreno Arroyo, M. Perla; Villar Álvarez, Fernando del

    2005-01-01

    El presente artículo trata de analizar la aplicación del feedback durante las sesiones de entrenamiento, en relación a las siguientes variables: recursos didácticos empleados en la corrección de la ejecución, tipo de feedback empleado en función de la intención del entrenador, recursos didácticos empleados para mejorar la conducta de corrección. Para llevarlo a cabo, se utilizó un cuestionario de autocumplimentación sobre una muestra compuesta por 20 entrenadores españoles de alta competi...

  20. Factores de riesgo, asociados a intento de suicidio, comparando factores de alta y baja letalidad

    OpenAIRE

    Garcia Rabago, Horacio; Sahagun Flores, Jose Ernesto; Ruiz Gomez, Alfonso; Sanchez Ureña, Gustavo Manuel; Tirado Vargas, Juan Carlos; Gonzalez Gamez, Jaime Guillermo

    2012-01-01

    Objetivo El propósito del estudio fue Identificar los factores de riesgo más frecuentes asociados a intento de suicidio para determinar si existen diferencias entre los factores de riesgo presentes en pacientes con tentativa de baja letalidad y los de alta letalidad. Método Se entrevistaron 106 pacientes de ambos sexos, con diagnóstico de intento de suicidio, hospitalizados en una unidad psiquiátrica, divididos en dos grupos: uno pacientes con tentativa suicida de baja letalidad y otro con te...

  1. Resultados del relevamiento de HI en el Cielo Austral: 3. Relevamiento de Nubes de Alta Velocidad

    Science.gov (United States)

    Morras, R.; Bajaja, E.; Arnal, E. M.; Pöppel, W. G. L.

    Los resultados del relevamiento de HI del Hemisferio Austral fueron reprocesados con el fin de incrementar su sensibilidad. Así, se utilizó esta nueva base de datos con el fin de obtener un nuevo relevamiento de Nubes de Alta Velocidad en el cielo austral. El ruido r.m.s. alcanzado es de 0.015-0.020 K, con una resolución espectral de 8 km/seg. El cubrimiento espacial del relevamiento mejora en un factor 16 al realizado por Bajaja et al (1985).

  2. Contribución al modelado unidimensional en motores de dos tiempos de altas prestaciones

    OpenAIRE

    JIMENEZ MACEDO, VICTOR DANIEL

    2013-01-01

    Un modelo de simulación presenta muchas ventajas en el campo del desarrollo de motores de combustión interna alternativos. Su utilidad es doble. Por un lado, para entender la naturaleza de los fenómenos físicos que suceden en el interior del motor, y por otro, con el fin de optimizar el diseño de los sistemas que integran el mismo. El principal objetivo de esta tesis es desarrollar un modelo de un motor de dos tiempos de 125 cc de altas prestaciones para caracterizar la fluidodinámica interna...

  3. Diseño de sistemas WIFI en trenes de alta velocidad

    OpenAIRE

    Alonso Barbero, Carlos

    2015-01-01

    En este Trabajo Fin de Grado se realiza el diseño de un sistema que proporcione acceso a internet a los usuarios en un tren de alta velocidad. Se busca conseguir un sistema inalámbrico (WIFI) que permita un gran número de conexiones simultáneas con un ancho de banda suficiente para todas ellas. En este proyecto se buscará una tecnología capaz de cumplir estos requisitos, realizando un estudio de las tecnologías disponibles actualmente (WiMAX, satélite, 3G/4G). Las diferentes tecnologías pr...

  4. Simulación de altas prestaciones para modelos orientados al individuo

    OpenAIRE

    Mostaccio, Diego Javier

    2007-01-01

    Existen diversos campos de la biología que necesitan realizar experimentos para estudiar el modelo de comportamiento de diferentes especies. En la presente tesis, se analizan las diferentes posibilidades de análisis en base a sistemas de simulación de altas prestaciones donde se ha desarrollado un laboratorio virtual que permite a los científicos experimentar con sus modelos y realizar pruebas mediante métodos de simulación distribuida. El modelo utilizado es un Modelo Orientado al Individuo ...

  5. ESTUDIO DE ALUMNOS DE EDUCACIÓN SECUNDARIA OBLIGATORIA CON ALTAS CAPACIDADES INTELECTUALES

    OpenAIRE

    Anda-Moreno, Verónica

    2012-01-01

    El presente Trabajo de Fin de Máster realizado para la obtención del título del Máster en Formación de Profesorado de Educación Secundaria Obligatoria, Bachillerato, Formación Profesional y Enseñanza de Idiomas, Especialidad en Física y Química, de la Universidad Internacional de La Rioja trata del estudio de Alumnos con Altas Capacidades Intelectuales de la Educación Secundaria Obligatoria del sistema educativo español. En el entorno escolar, siempre se han presentado casos de niños...

  6. Herramientas TIC para la intervención educativa en estudiantes con altas capacidades

    OpenAIRE

    Tárraga Mínguez, Raúl; Sanz-Cervera, Pilar; Pastor Cerezuela, Gemma; Fernández Andrés, María Inmaculada

    2014-01-01

    Los estudiantes con altas capacidades procesan la información de manera distinta, ya que estos poseen una elevada creatividad e implicación en la tarea. Este hecho implica la necesidad de llevar acabo una intervención educativa específica. Algunos modelos teóricos han demostrado la efectividad del uso de las TICs en la intervención de este tipo de alumnado, por lo que en el presente artículo se incluyen diferentes herramientas TIC que pueden ser de gran utilidad para los docentes. Entre estas...

  7. Altas capacidades. Propuesta de intervención para el aprendizaje de la historia

    OpenAIRE

    Gárriz Forné, Javier

    2013-01-01

    El presente estudio de carácter teórico, es una aproximación al conocimiento de las necesidades educativas del alumnado con altas capacidades intelectuales y pretende desarrollar una propuesta educativa que responda a esas necesidades, desde las ciencias sociales, concretamente desde la historia. Partiendo de la legislación vigente y teniendo en cuenta el planteamiento de algunos autores que abordan esta problemática, primero, comenzaré perfilando las características de este alumnado; pos...

  8. Alumnado con altas capacidades intelectuales: Programa de intervención

    OpenAIRE

    Arranz Melado, Luis Alfonso

    2015-01-01

    En el presente trabajo se hace un breve resumen conceptual de la literatura científica sobre las altas capacidades intelectuales. Se hace referencia a conceptos, teorías y modelos. Luego se analiza algunas de las características del alumnado con necesidades educativas especiales. Seguidamente, se hace referencia a los procedimientos y técnicas de evaluación de los estudiantes con necesidades educativas especiales. Se hace mención de las diferentes modalidades de respuesta educativa aplica...

  9. Procesos de automatización cognitiva en alumnado con altas capacidades intelectuales

    OpenAIRE

    Juan Montero-Linares; José I. Navarro-Guzmán; Manuel Aguilar-Villagrán

    2013-01-01

    Proponemos desde el enfoque del procesamiento de la información, el estudio de características cognitivas que faciliten la identificación de las altas capacidades. A tal fin, elaboramos una tarea de habilidad de segmentación silábica que, a partir del modelo propuesto por Baddeley sobre la memoria de trabajo y la distinción entre procesos automáticos y controlados, nos permitiese comprobar las diferencias en cuanto a la capacidad de automatización de la información y si los indicadores propue...

  10. Alumnos con altas capacidades intelectuales: Propuesta de Intervención

    OpenAIRE

    Cano-Aguirre, María Isabel

    2012-01-01

    En este trabajo se ha realizado una revisión bibliográfica acerca de las características de los alumnos de altas capacidades intelectuales, su funcionamiento cerebral y los proyectos que se aplican en la actualidad. En la segunda parte se ha realizado una investigación con un enfoque cualitativo en la cual se proporcionó un cuestionario a un grupo de profesionales que participan en proyectos dirigidos a este tipo de alumnado con el fin de detectar la situación actual en la que se encuentran. ...

  11. Género, adolescencia y altas capacidades : un acercamiento a la afectividad

    OpenAIRE

    González González, Leybiz

    2012-01-01

    El presente estudio fue realizado en un grupo de chicas y chicos adolescentes pertenecientes a la Asociación Onubense de Altas Capacidades ARETÉ. Sus propósitos consistieron en analizar el aspecto afectivo-relacional a través de una perspectiva de género, en la que fueron identificadas las vivencias y áreas de conflictos psicológicos, las preocupaciones, temores, satisfacciones e insatisfacciones presentes. Asimismo, se pretendió develar algunos elementos de la conformación de ...

  12. La evaluación psicopedagógica del alumnado con altas capacidades intelectuales

    OpenAIRE

    Moliner García, Odet; Comes Nolla, Gabriel; Luque, Antonio; Díaz Pareja, Elena María

    2008-01-01

    Tras un análisis de la normativa estatal y autonómica sobre la evaluación psicopedagógica del alumnado con altas capacidades intelectuales, se presentan los aspectos más relevantes que toda evaluación psicopedagógica debe contemplar para que resulte lo más eficaz posible, y permita ofrecer una respuesta educativa adecuada a dicho alumnado e identifique los recursos y apoyos que pueda precisar. Tales decisiones se concretan en el informe psicopedagógico y este artículo recoge...

  13. Alumnos con indicios de altas capacidades en Educación Infantil

    OpenAIRE

    López-Gómez, Sheila

    2012-01-01

    En las aulas se encuentran niños de altas capacidades que no han sido diagnosticados y por lo tanto no se está atendiendo a sus necesidades como se debiera. Mediante este trabajo de fin de grado se ha pretendido señalar las características principales que permiten al tutor del aula reconocer a estos alumnos y poderles derivar a los orientadores que señalarán las pautas necesarias para conseguir que el alumno se desarrolle en plenitud y se sienta integrado en el aula. Para ello se van a exp...

  14. SAÓ, sistema de ayuda ortoépica para la lectura en voz alta del valenciano

    OpenAIRE

    Forcada, Mikel L.; Beltran i Calvo, Vicent; Segura i Llopes, Carles; Colomina i Castanyer, Jordi

    2003-01-01

    Este proyecto se propone elaborar un programa informático que ayudará a los locutores de radio y televisión y, en general, a cualquier persona, a leer el valenciano correctamente en voz alta. El sistema resultante, denominado SAÓ (sistema de ayuda ortoépica), anotará automáticamente el texto con marcas sencillas que indicarán la pronunciación correcta en algunos casos difíciles, usando un ordenador de sobremesa común. En particular, podrá ser usado para enseñar l...

  15. Alta hospitalar do recém-nascido prematuro: experiência do pai

    OpenAIRE

    Bruna de Souza Lima Marski; Natália Custodio; Flávia Corrêa Porto de Abreu; Débora Falleiros de Melo; Monika Wernet

    2016-01-01

    RESUMO Objetivo: descrever a experiência do pai frente à alta do filho prematuro da Unidade de Terapia Intensiva Neonatal e apontar intervenções para a promoção dessa experiência. Método: pesquisa qualitativa com oito pais que adotou o Interacionismo Simbólico como referencial teórico e a pesquisa de narrativa temática como referencial metodológico. Resultados: a análise dos dados permitiu descrever a experiência do pai a partir de três unidades temáticas: 'limites para a paternidade', 'al...

  16. The Alta Stock, Utah: An Exemplar Rock Suite for Learning Metamorphic Concepts

    Science.gov (United States)

    Davidson, C.; Haileab, B.

    2003-12-01

    Using rock suites in a discovery-based setting is a terrific way to learn important petrologic processes and concepts such as the role of fluids during metamorphism, phase equilibrium, and metastability to name just a few. A particularly effective rock suite we use in our petrology course is from the contact aureole of the Tertiary Alta stock in Utah. The intrusion of the Alta stock into Paleozoic dolostone containing chert nodules produced a well-defined contact metamorphic aureole that includes talc-, tremolite-, forsterite-, and periclase-in field isograds (Cook and Bowman, 2000). Students work in free-form groups with collaboration between groups to define the mineral assemblages using hand samples and thin sections from throughout the areole and then work out what they think are the important petrologic processes that worked together to form what they see. The main goals of the exercise include: 1) learning to identify mineral assemblages common to metamorphosed siliceous dolostones; 2) learning to infer metamorphic reactions from progressive changes in mineral assemblages; 3) being able to identify balanced metamorphic reactions responsible for isograds mapped in the field; 4) begin to develop an understanding of how bulk composition and fluid composition controls mineral assemblages; and 5) learning how to infer the temperature and fluid composition evolution of the Alta stock aureole based on published T-X(CO2)diagrams. This suite is particularly effective because all the important minerals the students observe in thin section can be defined by the easy to plot and understand CaO-MgO-SiO2 system. This offers the opportunity to introduce (or reinforce) the concept of plotting minerals in composition space, using the phase rule to define the variance of your system, using tie lines to define stable mineral assemblages, and the flipping of tie lines to produce univariant reactions. In addition, the students work out the topology of these reactions in P-T space

  17. Impacto de la regulación ambiental en las actividades de la alta gerencia corporativa

    OpenAIRE

    Rina Tigrera Carneiro

    2003-01-01

    El presente ensayo tiene por finalidad exponer algunas consideraciones y reflexiones acerca del impacto que ha generado la regulación ambiental en las actividades de la alta gerencia corporativa. Para tal fin, fue necesario realizar una revisión documental de las distintas bibliografías, documentos y escritos especializados en el área, tanto en el ámbito nacional como latinoamericano; la cual, permitió llegar a las siguientes conclusiones: la introducción de las distintas regulaciones de índo...

  18. Computación de altas prestaciones ecológica

    OpenAIRE

    González, Lucía; Uribe, Federico; Balladini, Javier; Sánchez, Laura

    2011-01-01

    La computación de altas prestaciones ha tenido, por décadas, el único objetivo de incrementar la velocidad de procesamiento de las aplicaciones computacionalmente complejas. Dado el tamaño actual de las supercomputadoras, el consumo energético de las mismas es tan elevado que producen un tremendo impacto económico. Además, la falta de explotaci ón de las energías renovables y limpias hacen que la producción energética afecte signi- cativamente en lo ecológico y social. Estos factores nos ...

  19. Sincronização em sistemas integrados a alta velocidade

    OpenAIRE

    Figueiredo, Mónica Jorge Carvalho de

    2012-01-01

    A distribui ção de um sinal relógio, com elevada precisão espacial (baixo skew) e temporal (baixo jitter ), em sistemas sí ncronos de alta velocidade tem-se revelado uma tarefa cada vez mais demorada e complexa devido ao escalonamento da tecnologia. Com a diminuição das dimensões dos dispositivos e a integração crescente de mais funcionalidades nos Circuitos Integrados (CIs), a precisão associada as transições do sinal de relógio tem sido cada vez mais afectada por varia ções de proce...

  20. Neurodesarrollo en egresados de la terapia intensiva neonatal a los 6 meses del alta hospitalaria

    OpenAIRE

    Dayami Armas-Guerra; Tania Mejías-Martín; Ana Nastia Tamayo-Ortiz; María Caridad Jardines-Carballosa

    2012-01-01

    Se abordó estudio descriptivo longitudinal de 16 recién nacidos egresados del servicio de Neonatología del Hospital Pediátrico de Holguín, desde febrero a junio del 2009. Se les evaluó desde el punto de vista neurológico a los seis meses del alta hospitalaria. Un 25% presentaron anormalidad del examen neurológico. Las alteraciones leves y moderadas se comportaron igual. El sexo femenino fue el más afectado, la menor edad gestacional y el peso menor de 1500 gramos predispusieron a la aparición...