Estudio ab initio del mecanismo de la reacción HSO + O3

NASA Astrophysics Data System (ADS)

Nebot Gil, I.

La reacción entre el radical HSO y el ozono ha sido ampliamente estudiada desde el punto de vista experimental debido a la importancia que tiene el radical HSO en la oxidación de los compuestos de azufre reductores y a que puede contribuir a la producción de H2SO4 [1-4]. Se realizaron diversos estudios teóricos sobre la cinética de la reacción entre el radical HSO y el ozono. La reacción del HSO con el ozono presenta tres canales diferentes : HSO + O3 &rightarrow &HSO2 + O2 &rightarrow &HS + 2 O2 &rightarrow &SO + OH + O2 La controversia existente entre los grupos experimentales sobre cuál de las tres vías es la predominante, se ha resuelto mediante un estudio teórico de todas ellas utilizando métodos ab initio. La estructura de todos los reactivos, productos, intermedios y estados de transición ha sido optimizada a nivel ab initio utilizando los métodos UMP2 /6-31G** y QCISD/6-31G**.

Foot length measurements of newborns of high and low risk pregnancies.

PubMed

Salge, Ana Karina Marques; Rocha, Érika Lopes; Gaíva, Maria Aparecida Munhoz; Castral, Thaíla Correa; Guimarães, Janaína Valadares; Xavier, Raphaela Maioni

2017-03-09

Comparing foot length measurements of newborns in high and low risk pregnancies at a public hospital in Goiânia, GO, Brazil. A cross-sectional study carried out between April, 2013 and May, 2015, with a sample consisting of 180 newborns; 106 infants of women from high-risk pregnancies and 74 of women from low-risk pregnancies. Data were descriptively analyzed. Foot length measurement was performed using a stiff transparent plastic ruler, graduated in millimeters. The length of both feet was measured from the tip of the hallux (big toe) to the end of the heel. A statistically significant relationship was found between the foot length and newborn's weight, between the cephalic and thoracic perimeters in the high-risk group and between the cephalic perimeter in the control group. There is a need for creating cut-off points to identify newborns with intrauterine growth disorders using foot length. Comparar as medidas do comprimento hálux-calcâneo de recém-nascidos em gestações de alto e baixo risco em um hospital público de Goiânia, GO. Estudo transversal, realizado no período de abril de 2013 a maio de 2015, cuja amostra constituiu-se de 180 recém-nascidos, 106 filhos de mulheres com gestação de alto risco e 74 de mulheres com gestação de baixo risco. Os dados foram analisados descritivamente. A medida do comprimento hálux-calcâneo foi realizada utilizando-se de régua plástica transparente rígida, graduada em milímetros. Foram medidos ambos os pés, aferindo-se o comprimento da ponta do hálux até a extremidade do calcâneo. Foi encontrada relação estatisticamente significante entre o comprimento hálux-calcâneo e o peso do recém-nascido, entre os perímetros cefálico e torácico no grupo de alto risco e entre o perímetro cefálico no grupo controle. Existe necessidade da criação de pontos de corte para identificar recém-nascidos com desvios de crescimento intrauterino utilizando-se do comprimento hálux-calcâneo. Comparar las mediciones de la longitud hallux-calcáneo de los recién nacidos en embarazos de alto y bajo riesgo en un hospital público de Goiânia, GO.MÉTODOSEstudio transversal realizado de abril 2013 a mayo 2015, cuya muestra estuvo constituida por 180 recién nacidos, 106 de mujeres con embarazos de alto riesgo y 74 de mujeres con embarazos de bajo riesgo. Los datos se analizaron de manera descriptiva. La medida de la longitud hallux-calcáneo se realizó mediante regla de plástico rígido transparente, graduada en milímetros. Se midieron en ambos pies, las longitudes de la punta del hallux hasta el final del calcáneo. Se encontró una relación estadísticamente significativa entre la longitud hallux-calcáneo y el peso del recién nacido, entre las circunferencias cefálica y torácica en el grupo de alto riesgo y entre la circunferencia cefálica en el grupo control. Existe la necesidad de crear puntos de corte para identificar los recién nacidos con desviaciones de crecimiento intrauterino utilizando la longitud desde el hallux hasta el calcáneo.

Confidence Intervals for Omega Coefficient: Proposal for Calculus.

PubMed

Ventura-León, José Luis

2018-01-01

La confiabilidad es entendida como una propiedad métrica de las puntuaciones de un instrumento de medida. Recientemente se viene utilizando el coeficiente omega (ω) para la estimación de la confiabilidad. No obstante, la medición nunca es exacta por la influencia del error aleatorio, por esa razón es necesario calcular y reportar el intervalo de confianza (IC) que permite encontrar en valor verdadero en un rango de medida. En ese contexto, el artículo plantea una forma de estimar el IC mediante el método de bootstrap para facilitar este procedimiento se brindan códigos de R (un software de acceso libre) para que puedan realizarse los cálculos de una forma amigable. Se espera que el artículo sirva de ayuda a los investigadores de ámbito de salud.

Calidad de Imagen del Telescopio UNAM212

NASA Astrophysics Data System (ADS)

Cobos, F. J.; Teiada de Vargas, C.

1987-05-01

El telescopio UNAM2l2, del Observatorio Astronómico Nacional, situado en la Sierra de San Pedro Mártir (Baja California, México), cumplira en un futuro muy cercano siete años de uso para fines de investigación astronómica. Aunque en este tiempo no se ha efectuado un estudio sistemático acerca de su comportamiento óptico y de los factores que influyen en la calidad de las imágenes, se han realizado pruebas diversas, estudios parciales y reuniones especificas, cuyos resultados no siempre se han difundido ampliamente y generalmente no se han presentado por escrito. Es por ello que hemos creido necesario intentar una recopilación de la información existente para poder con ella establecer un diagnóstjco que, aunque no sea definitivo, sirva de base para futuros trabajos tendientes a optimizar el comportamiento óptico del telescopio. Es evidente que un buen número de las conclusiones que se presentan son resultado del trabajo de muchas personas ó de esfuerzos colectivos. Asimismo, hemos tratado de localizar información bibliográfica que pueda ser de utilidad. Nuestro objetivo primordial ha consistido en centrarnos en la óptica del telescopio y su calidad, pero también se han considerado otros aspectos que puedan afectar las imágenes obtenidas tales como: celda del primario, `seeing' local y externo, flexiones posibles en la estructura mecánica del telescopio, etc.

Calibração do sistema imageador do telescópio MASCO

NASA Astrophysics Data System (ADS)

Mejía, J.; D'Amico, F.; Villela, T.; Braga, J.

2003-08-01

O MASCO (MÁScara COdificada) é um telescópio imageador de raios-X e gama atualmente configurado para operar na faixa de 50 a 600 keV com uma resolução angular de 14 minutos de arco num campo de visada total circular de 23,5° de diâmetro. O MASCO está totalmente operacional e deverá ser lançado em um balão estratosférico no segundo semestre de 2003 para realizar observações durante ~20 horas a ~40 km de altitude. O telescópio utiliza uma máscara codificada de padrão uniformemente redundante modificado (MURA) de dimensões 19 ´ 19. Esse padrão pertence a uma subclasse de MURAs que apresenta anti-simetria de 90° e conseqüentemente permite a utilização da técnica de subtração de variações sistemáticas de ruído de fundo através de utilização da configuração anti-máscara, obtida com uma simples rotação da máscara. Neste trabalho apresentamos resultados de calibrações em laboratório que tiveram como objetivo testar o sistema imageador. Imagens de fontes radioativas foram obtidas com o telescópio em configuração de vôo, com a máscara girando. Serão discutidos os resultados desses testes e as técnicas desenvolvidas para eliminar ambigüidades de posição de fontes, otimização da relação sinal-ruído e observação de fontes fora do campo totalmente codificado. O sistema de máscara/antimáscara mostrou-se capaz de aumentar a relação sinal-ruído de ~60% para fontes intensas (100 s). Com a máscara girando, a técnica de reconstrução de imagens desenvolvida identificou a posição exata da fonte e não introduziu perda de sensibilidade. Imagens de uma fonte colocada a 8,3° - fora do campo totalmente codificado do telescópio -, mostraram uma diminuição de ~40% na relação sinal/ruído em relação ao centro do campo de visada, o que se deve à codificação incompleta pela máscara e à absorção parcial do fluxo pelos detectores de blindagem.

Survey infravermelho do braço espiral de scuttum e da barra no centro galáctico

NASA Astrophysics Data System (ADS)

Amôres, E. B.; Lépine, J. R. D.

2003-08-01

O survey infravermelho consiste de observações utilizando a CAMIV no telescópio de 60 cm do LNA. Nosso principal objetivo é melhor caracterizar a população estelar dos braços espirais e de uma estrutura existente no centro galáctico que acreditamos ser devido à existência de uma barra, cujas extremidades estariam localizadas em longitudes galácticas l~23° e l~14°. As observações realizadas em vários filtros (imagens J, H e K) são particularmente importantes nas direções que tangenciam os braços espirais, desta forma, comparamos uma direção que atravessa um braço a uma direção próxima que não passa pelo braço, sendo que ambas possuem a mesma contribuição de contagens foreground. Nas missões realizadas até o presente, observamos a região na direção tangencial ao braço de Scuttum, com observações de l = 30.04° até l = 31.04°, a cada intervalo de longitude de 0.1°, para latitude galáctica de 0.0°, 0.25°, 0.50°. Para as regiões que acreditamos serem as extremidades da barra, observamos as faixas de longitude compreendidas entre -15° £ l £ -13° e 24° £ l £ 22° a cada intervalo de 0.25°, para latitude galáctica de 0.0° e 0.25°. As observações nos filtros J e H foram feitas com tempo de integração de 60s, na banda K, as observações foram feitas utilizando o filtro C1 com tempo de integração de aproximadamente 210 s (12x15s). Elaboramos diagramas cor-cor e cor-magnitude onde podemos verificar a existência de regiões com diferentes contagens e população estelar à medida que um braço espiral é atravessado.

Medición de placas astrométricas obtenidas con el telescopio Astrográfico de La Plata

NASA Astrophysics Data System (ADS)

di Sisto, R. P.; Orellana, R.

El Observatorio de La Plata cuenta con un gran número de placas de asteroides y cometas obtenidas con el telescopio astrográfico, que cubren gran parte del cielo del hemisferio sur. En 1996 se recopilaron y clasificaron 2187 placas (Beca para estudiantes de la AAA 1996) de las cuales 2031 corresponden a asteroides. Los datos de cada placa se volcaron en una base de datos creada para facilitar su manejo y preservar la información. A partir de este trabajo se revisaron los MPC electrónicos y se identificaron aquellas placas de asteroides pertenecientes a nuestra base de datos cuyos resultados no fueron publicados en los mismos. De un total de 400 placas que no aparecían publicadas sobresalía un paquete constituído por 40 placas obtenidas en 1977. Estas últimas fueron reducidas utilizando las posiciones y movimientos propios de las estrellas de referencia obtenidas del catálogo SAO 2000 dadas para el sistema FK5. Las posiciones calculadas fueron enviadas y publicadas en los Minor Planet Circulars (MPC).

Fotometria diferencial de estrelas T Tauri

NASA Astrophysics Data System (ADS)

Pereira, P. C. R.; Santos-Júnior, J. M.; Cruz, W. S.

2003-08-01

Neste trabalho apresentamos os resultados preliminares de um monitoramento de estrelas jovens, que pretende ser de longa duração. As estrelas estão em sua maioria localizadas no complexo Lupus-Scorpius. Nosso objetivo principal é o estudo da variabilidade em escalas de tempo de minutos até vários dias para estrelas cujos períodos não estão determinados ou apresentam discrepâncias entre diferentes publicações. A técnica utilizada foi a fotometria diferencial, com exposições de 60s e 90s, com as câmaras CCD SBIG ST7E e ST8E acopladas aos telescópios Schmidt-Cassegrain LX200 (10 e 12 polegadas), instalados na Fundação Planetário da Cidade do Rio de Janeiro. Os primeiros resultados indicam que a técnica é bastante sólida com relação à instabilidade na transparência do céu, mesmo com o uso de telescópios de pequeno porte. Objetos de magnitude 14, no telescópio de 10 polegadas, apresentam dispersões na diferença de magnitudes das comparações, em torno de 0,008mag nas exposições de 60s. Note-se, ainda, que a dispersão pode ser melhorada utilizando-se a técnica de soma de imagens. Destacamos AK Sco, GW Lup, GQ Lup e TW Hya. AK Sco é uma binária que, apesar de ter a sua órbita e período cobertos espectroscopicamente (13,6dias), nunca teve seus eclipses estudados por meio de fotometria. GW Lup não tem período determinado na literatura. Temos acompanhado este objeto há alguns anos, e sugestões de períodos entre 5 e 6 dias têm sido encontradas. O objeto que mereceu maior atenção foi TW Hya por apresentar vários trabalhos fotométricos e espectroscópicos com resultados discrepantes quanto ao período rotacional, que varia de 1,8 a 4,4 dias (Rucinsky & Krautter 1983, A&A 121, 217; Herbst & Koret 1988, AJ 96, 1949; Mekkaden 1988, A&A 340, 135; Batalha et al. 2002, ApJ 580, 343). Dedicamos 13 noites para essa estrela, totalizando cerca de 2.000 pontos na curva de luz. Nossos dados indicam a presença de uma modulação com dois períodos possíveis: 2,2 ou 3,8 dias, além de variações irregulares superpostas. Foram observados, também, dois eventos súbitos, espaçados de uma hora, com amplitudes de 0,05mag e duração de aproximadamente 30 minutos. Admitindo-se que tal modulação seja originada por acréscimo sobre a superfície estelar, dois cenários são possíveis. No caso do menor período, apenas uma mancha quente seria visível. No outro caso, duas manchas seriam necessárias, explicando assim a presença de dois picos ao se colocar os pontos em fase.

[Not Available].

PubMed

Fehrman-Rosas, Pamela; Delgado-Sánchez, Claudia; Fuentes-Fuentes, Jessica; Hidalgo-Fernández, Andrea; Quintana-Muñoz, Carol; Yunge-Hidalgo, Wilma; Fernández-Godoy, Eloina; Durán-Agüero, Samuel

2016-06-30

Objetivo: asociar patrones alimentarios con la autopercepción del estado nutricional en estudiantes universitarios chilenos de Nutrición y Dietética.Material y métodos: estudio transversal en el que se evaluó a 634 estudiantes de Nutrición y Dietética, de los cuales un 86,4% eran mujeres. A cada alumno se le mostraron siete modelos anatómicos correspondientes a valores de índice de masa corporal (IMC) de 18, 22, 25, 27, 30, 35 y 40 kg/m2. Cada estudiante debía elegir el modelo con el que mejor se identificaba. Posteriormente, se realizó la evaluación antropométrica, se calculó el IMC real comparándolo posteriormente con el IMC percibido, y finalmente se le aplicó una encuesta alimentaria.Resultados: se observa que los sujetos que sobreestiman su peso presentan un menor porcentaje de cumplimiento en el consumo de frutas y verduras al día; en cambio, el mayor porcentaje de sujetos que sigue las recomendaciones se encuentra en el grupo que se ve igual. Hay unaasociación entre una buena percepción de la imagen corporal y el consumo de 3 o más porciones de frutas al día OR = 0,554 (IC 95%; 0,360-0,852), 2 o más porciones de verduras al día OR = 0,438 (IC 95%; 0,283-0,678) y un consumo de alcohol menor de una vez a la semanaOR = 0,451 (IC 95%; 0,270-0,752).Conclusión: los estudiantes que registran una ingesta adecuada de verduras y frutas autodefinen su alimentación como saludable e ideal y tienden a autopercibirse coherentemente en relación con su estado nutricional; además, estos sujetos son los que presentan una ingesta menor de alimentos poco saludables.

Reconstrução tridimensional de arcos magnéticos por tomografia

NASA Astrophysics Data System (ADS)

Simões, P. J. A.; Costa, J. E. R.

2003-08-01

Uma explosão solar é uma variação súbita do brilho que ocorre nas regiões ativas da atmosfera solar. Estas regiões são constituídas por um plasma magnetizado com intensa indução magnética e em cenários bem complexos como visto recentemente através de experimentos embarcados em satélites operando instrumentos em raios X moles e ultra-violeta distante. A energia magnética, que pode ser armazenada por um período de horas até dias em configurações magnéticas estressadas, é subitamente lançada na atmosfera solar e transferida para partículas como elétrons, prótons e núcleos pesados, que são acelerados e/ou aquecidos, produzindo radiação eletromagnética. A proposta final deste projeto é determinar as características espaciais de alta resolução da emissão e polarização girossincrotrônica de explosões solares em ambientes complexos de campos magnéticos. Os recentes resultados da emissão difusa em EUV apresentado pelos satélites TRACE e SOHO dos arcos magnéticos conectando as diferentes polaridades magnéticas sobre as regiões ativas possibilitam novas abordagens sobre o papel do campo magnético na emissão em rádio. Nesta etapa apresentamos os resultados da reconstrução da geometria tridimensional das linhas de força destes arcos utilizando técnicas tomográficas, a partir de imagens de alta resolução espacial obtidas pelo instrumento EIT (Extreme ultraviolet Imaging Telescope), além da modelagem das induções magnéticas por um campo dipolar e as densidades de partículas aceleradas. Utilizamos para a reconstrução geométrica, imagens tomadas em vários ângulos dos arcos devido à rotacão solar. Com estes resultados, daremos continuidade ao projeto, com os cálculos da transferência radiativa nos modos ordinário e extraordinário de propagação da radiação girossincrotrônica de explosões solares.

Detecção da fase impulsiva de uma explosão solar gigante até 405 GHz

NASA Astrophysics Data System (ADS)

Raulin, J.-P.; Makhmutov, V.; Kaufmann, P.; Pacini, A. A.; Luethi, T.; Hudson, H. S.; Gary, D. E.; Yoshimori, M.

2003-08-01

A explosão ocorrida no dia 25/08/2001 foi uma das mais intensas do presente ciclo solar em ondas de rádio de altas frequências. Foram medidas em ondas milimétricas e submilimétricas, aproximadamente, 105 e vários milhares de unidades de fluxo solar, respectivamente. Apresentamos um estudo deste evento em múltiplas frequências, desde microondas (1GHz), até ondas submilimétricas (405 GHz) detectadas pelo Telescópio Solar para ondas Submilimétricas (SST). Esta base de dados foi complementada utilizando-se o experimento Yohkoh, incluindo a emissão em raios-X duros e raios-g (até 100 MeV), e imagens em raios-X moles da região ativa envolvida. Enfocamos e discutimos principalmente os seguintes aspectos da fase impulsiva do evento: (i) as implicações deduzidas do espectro eletromagnético, obtido pela primeira vez até 405 GHz; (ii) a dinâmica da região ativa. Os resultados mostram que para explicar o espectro rádio observado, são necessários entre 3.5×1037 e 1.5×1039 elétrons acelerados acima de 20 keV em uma região de campo magnético entre 300 e 800 Gauss. A estimativa do fluxo de fótons que seria produzido por estes elétrons, mostra que grande parte deles não precipitou na baixa atmosfera. A evolução temporal da emissão em raios-X moles revela que a configuração magnética da região ativa foi muito dinâmica durante a fase impulsiva da explosão. Em particular, mostramos que a produção dos elétrons altamente energéticos foi iniciada junto com a aparição, na baixa coroa solar, de um novo sistema compacto de estruturas magnéticas. Este fato sugere que os locais de aceleração estão localizados na baixa atmosfera do Sol, como resultado da interação entre o novo sistema compacto e o campo magnético ambiente da região ativa.

The Douro estuarine plume: Detection, processes and dynamics =

NASA Astrophysics Data System (ADS)

Mendes, Renato Paulo dos Santos

O Douro e um dos maiores rios da Peninsula Iberica, constituindo a maior descarga de agua doce para o Oceano Atlântico na costa noroeste portuguesa. A sua pluma estuarina tem particular relevância na dinâmica costeira e na modulacao de fenomenos biogeoquimicos. Sao objetivos desta dissertacao contribuir para a compreensao dos processos fisicos associados a geracao e propagacao da pluma estuarina do Rio Douro no oceano, assim como para o conhecimento dos seus padroes de dispersao e da forma como estes alteram a hidrologia e a circulacao costeira, considerando os agentes forcadores tipicos deste fenomeno (caudal fluvial, vento e mare) e indices climaticos relevantes. Para concretizacao destes objetivos foram desenvolvidas e aplicadas metodologias inovadoras de processamento de dados de detecao remota, assim como novas implementacoes estuarinas e costeiras de modelos numericos. Atraves de imagens MODIS, otimizadas para o estudo de fenomenos costeiros, efetuou-se uma detecao rigorosa da pluma. Identificou-se uma relacao entre o sinal turbido nLw555 e o caudal, demonstrando-se este produto como um bom proxy para a observacao da pluma no oceano. As escalas temporais e espaciais da pluma foram caraterizadas atraves destas imagens, combinadas com dados de caudal fluvial, mare, vento e precipitacao, e tambem com indices climaticos relevantes. Para compreender a propagacao da pluma e caracterizar a sua dinâmica e impacto na circulacao costeira, foi desenvolvida uma aplicacao 3D de modelos estuarinos e costeiros com malhas aninhadas de resolucao variavel. Definiramse e analisaram-se diferentes cenarios de vento e descarga fluvial. A interacao da pluma do Rio Douro e do Minho foi ainda analisada atraves dos resultados de simulacoes baseadas num evento de inverno. Os compositos turbidos mostraram que a pluma e facilmente detetada quando o caudal e maior que 500 m3 s??1. A descarga fluvial e o vento sao os principais forcadores da sua propagacao, enquanto a mare e apenas importante na regiao proxima a embocadura do estuario. Observaram-se relacoes a uma escala interanual entre a turbidez da pluma e os indices climaticos East Atlantic e NAO, com uma correlacao maxima identificada com 1 e 3 meses de desfasamento, respetivamente. Com base nos resultados das simulacoes efetuadas, a pluma e classificada como de larga escala e de advecao superficial, apresentando caracteristicas de uma pluma prototipica. Em condicoes de caudal moderado a elevado, a descarga estuarina e suficiente para gerar uma corrente costeira para norte sem acao do vento. Em eventos de ventos leste, a propagacao da pluma e similar ao caso sem vento, com um aumento da velocidade da corrente. Uma corrente costeira para sul e unicamente identificada sob condicoes de forte vento de oeste. Ventos de norte tendem a estender a pluma para o largo, com uma inclinacao na direcao sudoeste, enquanto ventos de sul intensificam a corrente para norte, sendo a mistura das plumas do Douro e do Minho uma consequencia possivel. A analise desta interacao apontou a contribuicao do Douro como importante na estabilizacao da WIBP e nas trocas de agua entre o oceano e as Rias Baixas. A interacao da pluma do Douro com estuarios localizados a sul da sua foz e a confirmacao in situ da recirculacao observada nos resultados numericos afiguram-se como temas relevantes para investigacoes futuras. None

Diseno de una Actividad de Aprendizaje Basada en la Argumentacion Dialogica en un curso Virtual de Biotecnologia y su Incidencia en el Desarrollo de Competencias Cientificas

NASA Astrophysics Data System (ADS)

Ortiz Benavides, Fedra Lorena

El proposito de la investigacion fue evaluar la efectividad de una actividad de aprendizaje basado en la argumentacion dialogica en linea y su incidencia en el desarrollo de competencias cientificas. Se fundamenta en la teoria del aprendizaje socio cultural de Vigotsky (1984), los principios del diseno instruccional de la cognicion situada por Hung y Der-Thang (2001) y como estrategia se aplico la argumentacion dialogica utilizando el Modelo Argumentativo de Toulmin MAT (1984). El diseno experimental comparo dos grupos de estudiantes A y B en el curso virtual de Biotecnologia. El grupo A (experimental) desarrollo la discusion a partir de la estrategia disenada para este estudio y el grupo B (control) realizo la discusion desde las actividades tradicionales. El desarrollo de la competencia argumentativa se valoro con el instrumento de evaluacion para argumentacion dialogica en linea propuesta por Clark y Sampson (2008). La evaluacion de las competencias cientificas se realizo a partir de una postprueba. Los datos fueron analizados con pruebas estadisticas no parametricas. Los resultados de la investigacion, indicaron diferencias significativas en el nivel de la competencia argumental en el grupo experimental en comparacion al grupo control. Igualmente se demostro que existe una relacion positiva entre el nivel de desarrollo de la competencia argumentativa y el nivel de desarrollo de las competencias cientificas.

Computer and laboratory simulation in the teaching of neonatal nursing: innovation and impact on learning.

PubMed

Fonseca, Luciana Mara Monti; Aredes, Natália Del' Angelo; Fernandes, Ananda Maria; Batalha, Luís Manuel da Cunha; Apóstolo, Jorge Manuel Amado; Martins, José Carlos Amado; Rodrigues, Manuel Alves

2016-10-10

to evaluate the cognitive learning of nursing students in neonatal clinical evaluation from a blended course with the use of computer and laboratory simulation; to compare the cognitive learning of students in a control and experimental group testing the laboratory simulation; and to assess the extracurricular blended course offered on the clinical assessment of preterm infants, according to the students. a quasi-experimental study with 14 Portuguese students, containing pretest, midterm test and post-test. The technologies offered in the course were serious game e-Baby, instructional software of semiology and semiotechnique, and laboratory simulation. Data collection tools developed for this study were used for the course evaluation and characterization of the students. Nonparametric statistics were used: Mann-Whitney and Wilcoxon. the use of validated digital technologies and laboratory simulation demonstrated a statistically significant difference (p = 0.001) in the learning of the participants. The course was evaluated as very satisfactory for them. The laboratory simulation alone did not represent a significant difference in the learning. the cognitive learning of participants increased significantly. The use of technology can be partly responsible for the course success, showing it to be an important teaching tool for innovation and motivation of learning in healthcare. avaliar a aprendizagem cognitiva de estudantes de enfermagem na avaliação clínica neonatal a partir de um curso semipresencial com uso de simulação por computador e em laboratório; comparar a aprendizagem cognitiva dos estudantes em grupo controle e experimental ao testar a simulação em laboratório; e avaliar o curso semipresencial extracurricular oferecido sobre avaliação clínica do bebê pré-termo, segundo os estudantes. estudo quase-experimental com 14 estudantes portugueses contendo pré-teste, teste intermediário e pós-teste. As tecnologias oferecidas no curso foram serious game e-Baby, software instrucional de semiologia e semiotécnica e simulação em laboratório. Para a avaliação do curso e caracterização dos estudantes utilizou-se instrumentos de coleta de dados desenvolvidos para este estudo. Utilizou-se estatística não paramétrica: Mann-Whitney e Wilcoxon. O uso de tecnologias digitais validadas e de simulação em laboratório evidenciou diferença estatisticamente significativa (p=0,001) na aprendizagem dos participantes. O curso foi avaliado como muito satisfatório pelos mesmos. A simulação em laboratório isoladamente não representou diferença significativa no aprendizado. a aprendizagem cognitiva dos participantes aumentou significativamente. Considera-se que o uso de tecnologia foi responsável por parte do sucesso do curso, denotando ser uma importante ferramenta de inovação didática e motivação da aprendizagem na área da saúde. evaluar el aprendizaje cognitivo de estudiantes de enfermería en evaluación clínica neonatal, a partir de un curso semipresencial, utilizando simulación por computador y en laboratorio; comparar el aprendizaje cognitivo de los estudiantes, entre grupo control y experimental, comprobando la simulación en el laboratorio; y evaluar el curso semipresencial extracurricular ofrecido sobre evaluación clínica del bebé pretérmino, de acuerdo a los estudiantes. estudio casi experimental con 14 estudiantes portugueses, conteniendo preprueba, prueba intermedia y postprueba. Las tecnologías ofrecidas en el curso fueron serious game e-Baby, programa de instrucción en semiología y semiotecnia, y simulación en laboratorio. Para la evaluación del curso y caracterización de los estudiantes se utilizaron instrumentos de recolección de datos desarrollados para este estudio. Se utilizó la estadística no-paramétrica de Mann-Whitney y Wilcoxon. el uso de tecnologías digitales validadas y de simulación en laboratorio evidenció diferencia estadísticamente significativa (p=0,001) en el aprendizaje de los participantes. El curso fue evaluado como muy satisfactorio por los alumnos. La simulación en laboratorio, aisladamente, no presentó diferencia significativa en el aprendizaje. el aprendizaje cognitivo de los participantes aumentó significativamente. Se considera que el uso de la tecnología fue responsable por parte del éxito del curso, demostrando ser una importante herramienta de innovación didáctica y motivación del aprendizaje en el área de la salud.

Estudio de mutaciones en los genes IDH1 e IDH2 en una muestra de gliomas de población colombiana.

PubMed

Ricaurte, Orlando; Neita, Karina; Valero, Danyela; Ortega-Rojas, Jenny; Arboleda-Bustos, Carlos E; Zubieta, Camilo; Penagos, José; Arboleda, Gonzalo

2018-05-01

Introducción. Los gliomas son los tumores primarios más comunes del sistema nervioso central y se clasifican de I a IV según su grado de malignidad. En recientes investigaciones se ha encontrado que su aparición está relacionada con mutaciones en el exón 4 de los genes que codifican las deshidrogenasas de isocitrato 1 y 2 (IDH1: codón 132; IDH2: codón 172).Objetivo. Determinar la frecuencia de mutaciones en los genes IDH1 e IDH2 en una muestra de gliomas de pacientes colombianos.Materiales y métodos. La extracción de ADN se hizo a partir de tejido tumoral. El exón 4 de los genes IDH1 e IDH2 se amplificó mediante PCR utilizando iniciadores específicos y, posteriormente, se secuenciaron. Para la determinación de las mutaciones, se emplearon los programas 4Peaks y MAFFT.Resultados. Se determinó la presencia de mutaciones en el gen IDH1 en el 34 % de las muestras, con predominio de la mutación no sinónima R132H. En el 7,5 % de los casos se detectaron mutaciones en el gen IDH2, principalmente las mutaciones no sinónimas R172K y R172W.Conclusiones. La frecuencia de mutaciones en los genes IDH1 e IDH2 en la muestra fue similar a la reportada en otros estudios. El análisis de estas mutaciones puede ser importante como factor pronóstico y para su uso como potenciales blancos terapéuticos en gliomas.

Desarrollo de un receptor polarimétrico en banda S para aplicación en estudios radioastronómicos

NASA Astrophysics Data System (ADS)

Barberis, C. M.; Bava, J. A.; Sanz, A. J.

Desde el punto de vista tecnológico, el objetivo principal de este proyecto es desarrollar un cabezal de receptor en la frecuencia de 3.3 GHz, con una temperatura del sistema de 60 K y un ancho de banda de 140 MHz. El mismo será instalado en el foco primario de un reflector parabólico de 30 metros de diámetro que funcionará como radiómetro en el IAR. El receptor es del tipo polarimétrico, con lo cual permite la posibilidad de obtener las componentes de polarización lineal y circular. Para tal fin el cabezal constará de dos ramas receptoras que amplificarán la señal y la trasladarán a una frecuencia menor, (frecuencia intermedia), permitiendo de esa forma un mejor transporte de la señal a la sala de control para su posterior procesamiento. El receptor, además de tener características polarimétricas, podrá ser usado en el contínuo y en la línea, utilizando las ventajas observacionales y de procesamiento de señal que actualmente posee el IAR.

El diseño final del espectrógrafo de banco (EBASIM) para CASLEO

NASA Astrophysics Data System (ADS)

Simmons, J.; Levato, H.

Utilizando el código de óptica ACCOS V se ha finalizado el diseño del espectrógrafo de banco para CASLEO. En una comunicación anterior habíamos indicado que utilizaríamos un colimador de 150 mm de diámetro con un radio de curvatura de 1540 mm. Para el espejo cámara, que tiene un diámetro de 200 mm, el radio de curvatura es de 1200 mm, ambos radios con una tolerancia no mayor a los 3 mm. En la presente, se informa sobre los detalles finales del cálculo del espectrógrafo que incluye el cómputo para 5 longitudes de onda diferentes y alrededor de 100 rayos. En todos los casos el 75 % de energía está dentro de un diámetro de 13 micrones. El diseño ha sido probado entre 3500 Å hasta 9000 Å con resultados satisfactorios.

DEZ ANOS DE EXPERIÊNCIA DO COMITÊ DE ÉTICA EM PESQUISA DA SECRETARIA DE SAÚDE DO DISTRITO FEDERAL, BRASIL

PubMed Central

Novaes, Maria Rita C. G.; Guilhem, Dirce; Lolas, Fernando

2009-01-01

O objetivo deste artigo é relatar a experiência do Comitê de Ética em Pesquisa da Secretaria de Estado de Saúde do Distrito Federal (CEP/SES/DF) Brasil, durante o período de 10 anos a partir de sua fundação. Trata-se de uma avaliação descritiva e documental, na modalidade estudo de caso, utilizando-se a totalidade de projetos protocolados no CEP/SES/DF (N° 052/08) nesse período. As pendências mais freqüentes dos projetos foram: termo de consentimento livre e esclarecido (30%), folha de rosto (25%), metodologia (20%), curriculum vitae (12%), planilha de orçamento (9%), outros (4%). O relato das atividades do CEP/SES/DF no período de 10 anos revelou, através de sua produtividade, a legitimidade do processo de análise ética dos protocolos visando à proteção dos participantes da pesquisa. PMID:19888441

Populações estelares em galáxias HII

NASA Astrophysics Data System (ADS)

Westera, P.; Cuisinier, F.; Telles, E.; Kehrig, C.

2003-08-01

Analisamos o conteúdo estelar de 74 galáxias HII a partir do contínuo observado nos espectros ópticos dessas galáxias, utilizando métodos de síntese de população estelar. Descobrimos que todas as galáxias para as quais encontramos soluções contêm uma população estelar velha que domina a massa estelar, e numa maioria dessas também encontramos evidência de uma população de idade intermediaria além da geração jovem que está se formando agora. Concluímos que a formação estelar dessas galáxias se realiza em surtos individuais, Esses surtos são interrompidos por longos períodos de inatividade, com os primeiros consumindo a maior parte do gás. Sugerimos, portanto, que as galáxias HII sejam galáxias anãs normais flagradas em um período de surto.

Astronomy Teaching and Teachers Continuing Education: the Interdisciplinarity during a Total Lunar Eclipse. (Spanish Title: Enseñanza de la Astronomía y la Formación Continua de Profesores: la Interdisciplinariedad Durante un Eclipse Total de Luna.) Educação EM Astronomia E Formação Continuada de Professores: a Interdisciplinaridade Durante um Eclipse Lunar TOTAL

NASA Astrophysics Data System (ADS)

Langhi, Rodolfo

2009-07-01

This paper describes how 67 teachers from 23 cities, could awaken, in students, the scientific interest, using a natural astronomical phenomenon: a total lunar eclipse. Before and after of eclipse, meetings for continuing education were characterized by interdisciplinarity of astronomy and the importance of these observations. Working groups were formed by teachers and students, who organized the survey data, mobilizing the people in their cities. The results point ways about how to provide the scientific culture and the motivation to learn science in students, using approaches between the following communities: scientific, amateur and school. En este artículo se describe cómo 67 profesores de 23 ciudades, despertó el interés científico en los estudiantes mediante un fenómeno astronómico: un eclipse total de Luna. Antes y después del eclipse, reuniones para la formación continua se centraron en la interdisciplinariedad de la astronomía, y la importancia de las observaciones de este tipo de fenómeno. Profesores y estudiantes formaron grupos de trabajo para investigar datos durante el eclipse, con el participación de la comunidad en sus ciudades. Los resultados apuntan a las opciones que conducen a la cultura científica y la motivación para aprender la ciencia, utilizando las relaciones de los siguientes grupos: científicos, aficionados y la escuela. Este texto relata como 67 professores, provenientes de 23 cidades, puderam despertar, nos alunos, o interesse científico utilizando um fenômeno natural astronômico: um eclipse lunar total. O evento foi precedido e procedido por encontros de formação continuada, onde se caracterizou a interdisciplinaridade da astronomia e a importância das observações de fenômenos como estes. Grupos de trabalho foram formados por professores e alunos, que se organizaram para o levantamento conjunto de dados durante o fenômeno, além do envolvimento da comunidade em suas respectivas cidades. Os resultados apontam para caminhos que podem proporcionar a motivação e a cultura científica, através de aproximações entre as comunidades científica, amadora e escolar.

Eventos de Desconexão no Cometa P/Halley sob a Ótica do Modelo de Reconexão Magnética

NASA Astrophysics Data System (ADS)

Voelzke, M. R.; Matsuura, O. T.

1998-08-01

531 imagens contidas no The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al., 1992) cobrindo o período de setembro de 1985 a julho de 1986 foram analisadas visando identificar, caracterizar as propriedades e correlacionar estruturas morfológicas da cauda de plasma do cometa P/Halley. A análise revelou 47 eventos de desconexão (DEs) (Niedner & Brandt, 1979; Jockers, 1985; Celnik et al., 1988; Delva et al., 1991). A análise completa de todas as imagens encontra-se publicada em Voelzke & Matsuura, 1998. A distribuição dos DEs na distância heliocêntrica apresenta um caráter bimodal possivelmente associado com a distribuição espacial das fronteiras de setor magnético do meio interplanetário. Os 47 DEs fotografados em 47 imagens distintas permitiram determinar 19 origens de DEs, ou seja, o instante em que supostamente o cometa cruzou a fronteira entre setores magnéticos do vento solar. Tais dados cometários foram comparados com dados do vento solar provenientes de medidas realizadas in situ pelas sondas IMP-8, ICE e PVO, que mediram a variação da velocidade do vento solar, da densidade e da pressão dinâmica durante o intervalo analisado. Os dados destas sondas espaciais em conjunto com os da sonda Vega 1 foram usados para determinar o tempo das passagens do lençol de corrente. Com base nos dados das sondas foram calculadas as coordenadas heliográficas retroativas do lençol de corrente na "superfície fonte" dos mapas sinóticos do campo magnético de Hoeksema, 1989. O cálculo retroativo é feito através de um modelo simples de expressão do vento solar com velocidade uniforme, sendo considerada a co-rotação da magnetosfera com o Sol. Este trabalho apresenta os resultados desta comparação e a análise cinemática da origem dos DEs, determinada sob a hipótese que o plasma desconectado de um dado DE afasta-se com velocidade constante do núcleo cometário (Voelzke & Matsuura, 1998) e compara esta análise com outras que determinam o tempo de desconexão a partir de um movimento linear constantemente acelerado (Yi et al., 1994). A velocidade de um DE para outro varia enormemente. - Brandt, J.C., Niedner, M.B.Jr. and Rahe, J., (1992) The International Halley Watch Atlas of Large-Scale Phenomena (printed by: Johnson Printing Co., Boulder, CO), University of Colorado-Boulder. - Celnik, W.E., Koczet, P., Schlosser, W., Schulz, R., Svejda, P. and Weissbauer, K., (1988) Astron. Astrophys. Suppl. Ser. 72, 89. - Delva, M., Schwingenschuh, K., Niedner, M.B.Jr. and Gringauz, K.I., (1991) Planet. Space Sci. 39, Number 5, 697. - Hoeksema, J.T., (1989) Adv. Space Res. 9, 141. - Jockers, K., (1985) Astron. Astrophys. Suppl. Ser. 62, 791. - Niedner, M.B.Jr. and Brandt, J.C., (1979) Astrophys. J. 234, 723. - Voelzke, M.R. and Matsuura, O.T., (1988) Planet. Space Sci. 46, 835. - Yi, Y., Caputo, M.F. and Brandt, J.C., (1994) Planet. Space Sci. 42, Number 9, 705.

Estudio del CH interestelar

NASA Astrophysics Data System (ADS)

Olano, C.; Lemarchand, G.; Sanz, A. J.; Bava, J. A.

El objetivo principal de este proyecto consiste en el estudio de la distribución y abundancia del CH en nubes interestelares a través de la observación de las líneas hiperfinas del CH en 3,3 GHz. El CH es una molécula de amplia distribución en el espacio interestelar y una de las pocas especies que han sido observadas tanto con técnicas de radio como ópticas. Desde el punto de vista tecnológico se ha desarrollado un cabezal de receptor que permitirá la realización de observaciones polarimétricas en la frecuencia de 3,3 GHz, con una temperatura del sistema de 60 K y un ancho de banda de 140 MHz, y que será instalado en el foco primario de la antena parabólica del IAR. El cabezal del receptor es capaz de detectar señales polarizadas, separando las componentes de polarización circular derecha e izquierda. Para tal fin el cabezal consta de dos ramas receptoras que amplificarán la señal y la trasladarán a una frecuencia más baja (frecuencia intermedia), permitiendo de esa forma un mejor transporte de la señal a la sala de control para su posterior procesamiento. El receptor además de tener características polarimétricas, podrá ser usado en el continuo y en la línea, utilizando las ventajas observacionales y de procesamiento de señal que actualmente posee el IAR.

Detección automática de NEOs en imágenes CCD utilizando la transformada de Hough

NASA Astrophysics Data System (ADS)

Ruétalo, M.; Tancredi, G.

El interés y la dedicación por los objetos que se acercan a la órbita de la Tierra (NEOs) ha aumentado considerablemente en los últimos años, tanto que se han iniciado varias campañas de búsqueda sistemática para aumentar la población identificada de éstos. El uso de placas fotográficas e identificación visual está siendo sustituído, progresivamente, por el uso de cámaras CCD y paquetes de detección automática de los objetos en las imágenes digitales. Una parte muy importante para la implementación exitosa de un programa automatizado de detección de este tipo es el desarrollo de algoritmos capaces de identificar objetos de baja relación señal-ruido y con requerimientos computacionales no elevados. En el presente trabajo proponemos la utilización de la transformada de Hough (utilizada en algunas áreas de visión artificial) para detectar automáticamente trazas, aproximadamente rectilíneas y de baja relación señal-ruido, en imágenes CCD. Desarrollamos una primera implementación de un algoritmo basado en ésta y lo probamos con una serie de imágenes reales conteniendo trazas con picos de señales de entre ~1 σ y ~3 σ por encima del nivel del ruido de fondo. El algoritmo detecta, sin inconvenientes, la mayoría de los casos y en tiempos razonablemente adecuados.

INTERVENCIÓN EDUCATIVA EFECTIVA EN VIH PARA MUJERES

PubMed Central

Miner, Sarah; Poupin, Lauren; Bernales, Margarita; Ferrer, Lilian; Cianelli, Rosina

2016-01-01

RESUMEN En Chile se estima que aproximadamente 38 mil personas viven con el Virus de Inmunodeficiencia Humana [VIH]. En el año 2001, 1.092 mujeres chilenas vivían con VIH, actualmente se cree que hay más de 7.600 mujeres con el virus. Frente a estas cifras surge la necesidad de crear estrategias de prevención dirigidas a mujeres chilenas. Objetivo analizar los estudios ya realizados en la prevención de VIH para determinar qué aspectos se deben incluir en programas exitosos de prevención de VIH en mujeres. Diseño y Método se realizó una revisión de la literatura utilizando la base de datos Proquest, CINAHL, Pubmed y Scielo. Los límites comprendieron: textos completos, de los últimos 10 años, de acceso gratuito y escrito en español o inglés. Se seleccionaron 15 artículos para la revisión. Resultados todos los artículos comprenden la evaluación del efecto de una intervención sobre conocimiento y conductas relacionadas con VIH/SIDA. Catorce muestran resultados significativos en cambios positivos de conducta o conocimientos relacionados con la prevención de VIH. Conclusiones los programas de prevención de VIH en mujeres pueden ser efectivos para lograr cambios de conducta y de conocimiento. Las intervenciones exitosas son aquellas basadas en teorías o modelos de prevención y en cambios de conductas, todas adaptadas a la cultura de la población estudiada. PMID:27667897

Desarrollo de un instrumento para medir percepciones sobre el contexto de construccion del conocimiento cientifico de estudiantes universitarios de nuevo ingreso

NASA Astrophysics Data System (ADS)

Garcia-Ramirez, Jaime Antonio

En esta investigacion, se desarrollo un instrumento que permite medir percepciones relacionadas al contexto de constriccion del conocimiento cientifico. Se examinaron instrumentos existentes y se encontro que el VOSTS (Views on science, technology, and society), instrumento desarrollado empiricamente en Canada por Aikenhead, Ryan y Fleming, podia traducirse y validarse en el contexto cultural puertorriqueno. El instrumento es extenso, consta de 113 reactivos, cada uno con una premisa basica relacionada a la tematica ciencia, tecnologia y sociedad y un numero de alternativas relacionadas a la premisa que oscila entre siete y trece. Se delimito su utilizacion a los quince reactivos identificados por los autores como relacionados a la construccion social del conocimiento cientifico. Metodologicamente, se procedio a utilizar el modelo de adaptacion intercultural, que permite que el instrumento desarrollado satisfaga las dimensiones de equivalencia semantica, de contenido, tecnica, de criterio y conceptual, atemperado asi al instrumento original. Se cumplio con este proposito mediante la traduccion de la version original en ingles al espanol y viceversa. Se utilizaron comites para examinar la traduccion y la retro-traduccion del instrumento. Se realizo una prueba piloto con estudiantes universitarios de nuevo ingreso, utilizando el instrumento traducido para asegurar su intelegibilidad. La confiabilidad del instrumento se determino mediante la intervencion de un panel de expertos quienes clasificaron las distintas posiciones dentro de cada reactivo en: realista, con merito e ingenua; se transformaron estas opciones en valores numericos lo que permitio establecer una escala Likert para cada una. Se suministro el instrumento a una muestra de estudiantes universitarios de nuevo ingreso con caracteristicas similares a las de la poblacion puertorriquena en cuanto a ejecucion en las pruebas de aptitud verbal y matematica del College Board. Los resultados de sus contestaciones fueron transformados numericamente para poder obtener el coeficiente de correlacion de Spearman-Brown para el instrumento (0.661, p < 0.01). El analisis de las contestaciones de los estudiantes refleja percepciones diversas y, en algunos casos, contradictorias con respecto al contexto de construccion del conocimiento cientifico.

Fontes binárias supermoles de raios X

NASA Astrophysics Data System (ADS)

Pires, A. M.; Janot Pacheco, E.

2003-08-01

Estuda-se as características físicas das fontes supermoles (de raios X (SSS), utilizando dados ópticos e em altas energias, no âmbito de um trabalho de IC. Trata-se de binárias que apresentam espectro X muito mole, baixas temperaturas e altas luminosidades bolométricas. Esse sistemas são compostos por uma anã branca realizando fusão em sua superfície, a partir de matéria perdida pela estrela companheira. Os resíduos de fusão se acumulam na superfície da anã branca, e essa pode ultrapassar o limite de Chadrasekhar, produzir um colapso gravitacional, sendo esse um dos cenários propostos para as explosões de SN Ia. Apresentamos nesta comunicação o estado da arte das características físicas das fontes SSS, situando-as no âmbito das VCs. Procuramos também situar esses objetos em relação às variáveis galácticas V Sge, na medida em que os dois grupos apresentam certas caracerísticas bastante semelhantes.A metodologia adotada é aquela pedagógico-cognitiva clássica de um trabalho de IC na área de ciências exatas.

Estructura espacial de las órbitas caóticas en un modelo autoconsistente de galaxia elíptica

NASA Astrophysics Data System (ADS)

Muzzio, J. C.

Hemos logrado construir modelos autoconsistentes de sistemas estelares utilizando una aproximación cuadrupolar para el potencial. Esto nos permite determinar órbitas y exponentes de Lyapunov de objetos que tienen posiciones y velocidades equivalentes a las que se obtienen de la funcón de distribución del sistema. La distribución espacial de las órbitas caóticas exhibe considerable estructura y, lo que es más importante aún, los valores de los exponentes de Lyapunov calculados sobre intervalos finitos de tiempo, muestran una fuerte correlación con el comportamiento de la órbita en esos mismos intervalos, por lo que permiten reconocer distintos subsistemas con diferentes distribuciones espaciales.

Aceptabilidad del diagnóstico rápido casero para HIV entre hombres gay y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires

PubMed Central

Balán, Iván C.; Carballo-Diéguez, Alex; Marone, Rubén O.; Pando, María A.; Barreda, Victoria; Ávila, María M.

2011-01-01

Resumen El uso del diagnóstico rápido para HIV en Argentina, así como otros países de Latinoamérica, ha sido limitado hasta el momento. Este trabajo reporta los resultados provenientes de un estudio cualitativo realizado entre hombres gays y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires, Argentina. El objetivo principal del mismo fue conocer las ventajas y desventajas que los hombres G&HSH perciben en relación al diagnóstico rápido casero para HIV. Se realizaron ocho grupos focales con 73 participantes en los cuales se discutió acerca de las ventajas y desventajas del uso de los diagnósticos rápidos. Las respuestas fueron codificadas utilizando un programa para análisis de datos cualitativos (NVivo) y analizadas temáticamente. Los participantes describieron numerosas ventajas sobre el uso del diagnóstico rápido casero, aunque algunos reportaron importantes preocupaciones dentro de las cuales se destaca la posibilidad de impulsos suicidas si alguien recibe un resultado positivo estando solo. En términos generales se observó una gran aceptabilidad para el uso del diagnóstico rápido si el mismo es realizado por personal de salud en lugares acondicionados para este fin. PMID:25284951

Segundo Catálogo Estelar del Hemisferio Sur con Astrolabio Fotoeléctrico PAII

NASA Astrophysics Data System (ADS)

Manrique, W. T.; Podestá, R. C.; Alonso, E.; Actis, E. V.; Pacheco, A. M.; Bustos, G.; Lizhi, L.; Zezhi, W.; Fanmiao, Z.; Hongqi, W.; Perdomo, R.

Recordamos que entre el Observatorio Astronómico ``Félix Aguilar'', el Observatorio Astronómico de Beijing y el Observatorio Astronómico de La Plata, se ha convenido en desarrollar un Proyecto de Investigación conjunto, para la observación sistemática de estrellas en el Hemisferio Sur, con el objeto de la elaboración de un Catálogo Estelar Global utilizando un Astrolabio Fotoeléctrico PAII del Observatorio de Beijing, que ha sido usado con éxito en la República de China. En este trabajo se presenta el Segundo Catálogo Estelar del Hemisferio Sur, derivado de las observaciones realizadas con el PAII instalado en el OAFA, durante el períiodo Febrero de 1992 a Marzo de 1997. En este lapso se han observado mas de 400000 pasajes estelares, obteniéndose las correcciones Δ α y Δ δ de 5241 estrellas del FK4, FK5, FK5 Ext., SRS, CAMC y GC. Las precisiones medias son del orden de ± 3,2 ms en ascensión recta y ±0."057 en declinación. Rango de magnitudes : 2,0 a 11,5 Rango de declinaciones : -3o a -60o Epoca Media : 1994.9 Se analizan los residuos en función de la magnitud y tipo espectral, correcciones de grupo y frecuencia de distribución Δ α y Δ δ.

Aceptabilidad del diagnóstico rápido casero para HIV entre hombres gay y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires.

PubMed

Balán, Iván C; Carballo-Diéguez, Alex; Marone, Rubén O; Pando, María A; Barreda, Victoria; Avila, María M

2011-03-01

El uso del diagnóstico rápido para HIV en Argentina, así como otros países de Latinoamérica, ha sido limitado hasta el momento. Este trabajo reporta los resultados provenientes de un estudio cualitativo realizado entre hombres gays y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires, Argentina. El objetivo principal del mismo fue conocer las ventajas y desventajas que los hombres G&HSH perciben en relación al diagnóstico rápido casero para HIV. Se realizaron ocho grupos focales con 73 participantes en los cuales se discutió acerca de las ventajas y desventajas del uso de los diagnósticos rápidos. Las respuestas fueron codificadas utilizando un programa para análisis de datos cualitativos (NVivo) y analizadas temáticamente. Los participantes describieron numerosas ventajas sobre el uso del diagnóstico rápido casero, aunque algunos reportaron importantes preocupaciones dentro de las cuales se destaca la posibilidad de impulsos suicidas si alguien recibe un resultado positivo estando solo. En términos generales se observó una gran aceptabilidad para el uso del diagnóstico rápido si el mismo es realizado por personal de salud en lugares acondicionados para este fin.

Presentación del estudio "Links" de hombres que tienes sexo con hombres en Buenos Aires, Argentina.

PubMed

Carballo-Diéguez, Alex; Avila, María M; Balán, Iván C; Marone, Rubén; Pando, María A; Barreda, Victoria

2011-03-01

Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos ("teteras"), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA.

Astronomia Motivadora no Ensino Fundamental

NASA Astrophysics Data System (ADS)

Melo, J.; Voelzke, M. R.

2008-09-01

O objetivo principal deste trabalho é procurar desenvolver o interesse dos alunos pelas ciências através da Astronomia. Uma pesquisa com perguntas sobre Astronomia foi realizada junto a 161 alunos do Ensino Fundamental, com o intuito de descobrir conhecimentos prévios dos alunos sobre o assunto. Constatou-se, por exemplo, que 29,3% da 6ª série responderam corretamente o que é eclipse, 30,0% da 8ª série acertaram o que a Astronomia estuda, enquanto 42,3% dos alunos da 5ª série souberam definir o Sol. Pretende-se ampliar as turmas participantes e trabalhar, principalmente de forma prática com: dimensões e escalas no Sistema Solar, construção de luneta, questões como dia e noite, estações do ano e eclipses. Busca-se abordar, também, outros conteúdos de Física tais como a óptica na construção da luneta, e a mecânica no trabalho com escalas e medidas, e ao utilizar uma luminária para representar o Sol na questão do eclipse, e de outras disciplinas como a Matemática na transformação de unidades, regras de três; Artes na modelagem ou desenho dos planetas; a própria História com relação à busca pela origem do universo, e a Informática que possibilita a busca mais rápida por informações, além de permitir simulações e visualizações de imagens importantes. Acredita-se que a Astronomia é importante no processo ensino aprendizagem, pois permite a discussão de temas curiosos como, por exemplo, a origem do universo, viagens espaciais a existência ou não de vida em outros planetas, além de temas atuais como as novas tecnologias.

Los manuales de quimica en Espana (1788--1845): Protagonistas, terminologia, clasificaciones y orden pedagogico

NASA Astrophysics Data System (ADS)

Munoz Bello, Maria Rosa

La presente tesis doctoral es una investigacion sobre los manuales de quimica utilizados en Espana de 1788 a 1845. Este trabajo proporciona una perspectiva general de un tema relevante en las ultimas decadas en Historia de la Ciencia, el estudio de los libros de texto. De acuerdo con las ultimas investigaciones realizadas en este terreno, el acto pedagogico es considerado como un proceso creativo, como espacio de encuentro de actores e intereses muy diversos, matizando las ideas defendidas por Thomas S. Kuhn. Recordemos que segun Kuhn, los libros de texto ofrecen una vision consensuada y normalizada del estado de la ciencia de su epoca, por lo que sus autores eliminan deliberadamente toda controversia y presentan asi una imagen distorsionada de la actividad cientifica. En cambio, se ha mostrado, por ejemplo, que en la ensenanza participan no solamente profesores y alumnos sino tambien otros muchos actores y todos ellos no unicamente con intereses puramente pedagogicos sino tambien con diversos intereses politicos y economicos que pueden conocerse a traves del estudio de los manuales. En esta tesis se pretende analizar los manuales de quimica en Espana desde 1788 hasta 1845. Para poder llevar a cabo la investigacion ha sido necesario precisar el objeto de estudio (libro de texto de quimica) durante el periodo estudiado (1788-1845) ya que no es adecuado adoptar la imagen actual de una disciplina que sufrio sustanciales cambios durante la epoca estudiada. Esta investigacion se centra en un momento especialmente importante para la quimica y que algunos historiadores han llegado a considerar "revolucionario". Durante estos anos se produjo un cambio importante en las teorias quimicas sobre la combustion y el concepto de elemento, asi como una reforma terminologica que originaron la aparicion de importantes controversias. Ademas, debido a la relacion de la quimica con otras disciplinas como la historia natural o la fisica ha sido necesario restringir el objeto de estudio para poder llegar a conclusiones validas. Por ello, se ha adoptado como nucleo de este trabajo la definicion de libro de texto basada en su destino y no en su funcion, es decir, los libros que de forma explicita expresan su finalidad didactica, tanto en el titulo o como en las declaraciones del autor reflejadas en el prologo de la obra, en los que ademas aparezca la palabra quimica en su titulo. El estudio comienza en 1788 con la publicacion de algunos de los primeros manuales de quimica modernos, y acaba con la reforma educativa de 1845, que tuvo importantes consecuencias en el mercado de libros de texto en Espana. Esta reforma separaba la ensenanza media de la propiamente universitaria y, de este modo, fue impulsora de la creacion de institutos provinciales de segunda ensenanza, algunos de los cuales habian comenzado su andadura en los anos anteriores. Las regulaciones introducidas suponian una fuerte limitacion para los profesores en la eleccion de los manuales de ensenanza que debian ser aprobados cada tres anos por el Consejo de Instruccion Publica. Ademas supuso una reglamentacion clara de los estudios de filosofia y su division en los estudios elementales y superiores. La investigacion se ha distribuido a lo largo de seis capitulos: Introduccion, los protagonista, el vocabulario de la quimica, poniendo orden: las clasificaciones quimicas, conclusiones y apendice. En primer lugar, se ha elaborado un repertorio bibliografico, incluido en el apendice, constituido por 76 obras de quimica publicadas en Espana desde 1788 hasta 1845 que permite realizar un analisis estadistico de su produccion. Posteriormente, se intenta conocer los principales protagonistas en la creacion del libro: editores, impresores, autores, traductores y lectores. Tradicionalmente los historiadores de la ciencia han dado mas importancia a los laboratorios y a los personajes de la investigacion cientifica, frente a las aulas y a los protagonistas de la ensenanza. La situacion ha cambiado en las ultimas decadas pues los trabajos mas recientes han mostrado la labor creativa que se desarrolla en las aulas de ciencias, su importante influencia en la configuracion de las sucesivas generaciones de cientificos y, por ello, la necesidad de prestar atencion a los profesores y estudiantes de ciencias, a los autores, impresores y editores de los libros de texto y otros personajes poco conocidos. Siguiendo estas tendencias, se revisa los principales protagonistas de la edicion de los libros de texto: (1) Los editores, impresores y libreros (incluyendo tambien la regulacion del mercado editorial), (2) Los autores y los traductores de las obras, (3) Los publicos destinatarios. Se ofrece una descripcion general de las principales tendencias y retratos colectivos que se combinan con detalles de algunos de los protagonistas y situaciones particulares que pueden ser reveladoras de cuestiones importantes que no pueden ser abordadas mediante graficas o estadisticas. (Abstract shortened by UMI.).

Astronomy in High School: Using a Mini-Planetarium to Understand Details of the Apparent Movement of Stars. (Spanish Title: Astronomía en la Escuela Secundaria: Comprendiendo los Detalles del Movimiento Aparente de Las Estrellas con un Miniplanetario.) Astronomia no Ensino Médio: Compreendendo Detalhes do Movimento Aparente das Estrelas com um Miniplanetário

NASA Astrophysics Data System (ADS)

dos Santos Leão, Demetrius

2013-07-01

The aim of this article is to present part of the results obtained by the intervention made from the author's Master degree project, which consisted in the development of a set of Astronomy classes for first year of High School students from a private school in the "Distrito Federal", Brasilia, Brazil, making use of a didactical material called mini-planetarium (MP) as the main resource. Using Paulo Freire's contextualization and dialogicity ideas as a theoretical framework guided by these lessons, it was proposed to the students the assembly and application of that resource in a planetarium session. During the project, some subjects such as the apparent trajectory of stars through Brasilia's sky, the location of the cardinal points beginning from the Southern Cross constellation, the color of stars and the stars being seen from a particular place were emphasized. It was found that the students showed an improvement of their understanding about these subjects, as well as a significant excitement with the developed methodology. El objetivo de este trabajo es presentar algunos de los resultados obtenidos en el proyecto de la tesis de maestría del autor, que incluyó el desarrollo de algunas clases de Astronomía, con estudiantes del primer año del bachillerato de una escuela privada del Distrito Federal (Brasilia, Brasil), utilizando como materia prima didáctica el recurso llamado miniplanetario (MP). Utilizando como base teórica orientadora de esas clases las ideas de contextualización y dialógica de Paulo Freire, fue propuesto a los estudiantes el montaje y la utilización de este recurso en una función de planetario. Durante el proyecto, se enfatizaron asuntos tales como la trayectoria aparente de las estrellas del cielo de Brasilia, la ubicación de los puntos cardinales a partir de la constelación de la Cruz del Sur, los colores de las estrellas y las estrellas vistas desde una localidad determinada. Se constató que los estudiantes mostraron una mejora en la comprensión de estas cuestiones y demostraron un gran interés por esta metodología. O objetivo deste artigo é apresentar parte dos resultados obtidos com a intervenção feita como projeto da dissertação de mestrado do autor, que consistiu no desenvolvimento de um conjunto de aulas de Astronomia, com alunos do 1º Ano do Ensino Médio de uma escola da rede privada do Distrito Federal (Brasília, Brasil), empregando como recurso principal um material didático chamado miniplanetário (MP). Utilizando como pressuposto teórico norteador dessas aulas as ideias de contextualização e dialogicidade de Paulo Freire, foi proposta aos estudantes a montagem e utilização desse recurso em uma sessão de planetário. Durante o projeto, enfatizaram-se assuntos como a trajetória aparente das estrelas para o céu de Brasília, a localização dos pontos cardeais a partir da constelação do Cruzeiro do Sul, as cores das estrelas e as estrelas vistas de uma determinada localidade. Apurou-se que os alunos apresentaram melhoria na compreensão desses assuntos, bem como demonstraram expressiva empolgação com essa metodologia desenvolvida.

Construction and validation of a tool to Assess the Use of Light Technologies at Intensive Care Units.

PubMed

Marinho, Pabliane Matias Lordelo; Campos, Maria Pontes de Aguiar; Rodrigues, Eliana Ofélia Llapa; Gois, Cristiane Franca Lisboa; Barreto, Ikaro Daniel de Carvalho

2016-12-19

to construct and validate a tool to assess the use of light technologies by the nursing team at Intensive Care Units. methodological study in which the tool was elaborated by means of the psychometric method for construction based on the categorization of health technologies by Merhy and Franco, from the National Humanization Policy, using the Nursing Intervention Classification taxonomy to categorize the domains of the tool. Agreement Percentages and Content Validity Indices were used for the purpose of validation. The result of the application of the Interrater Agreement Percentage exceeded the recommended level of 80%, highlighting the relevance for the proposed theme in the assessment, with an agreement rate of 99%. the tool was validated with four domains (Bond, Autonomy, Welcoming and Management) and nineteen items that assess the use of light technologies at Intensive Care Units. construir e validar um instrumento para avaliação do uso de tecnologias leves, pela equipe de enfermagem, em Unidades de Terapia Intensiva. estudo metodológico no qual o instrumento foi elaborado utilizando o método psicométrico para construção com base na categorização das tecnologias em saúde de Merhy e Franco, da Política Nacional de Humanização, utilizando-se a taxonomia Nursing Intervention Classification para categorizar os domínios do instrumento. Utilizou-se o Percentual de Concordância e o Índice de Validade de Conteúdo (IVC) para validação. o resultado da aplicação do Percentual de Concordância entre os juízes foi superior ao recomendado de 80%, havendo destaque na avaliação da pertinência ao tema proposto, apresentando um percentual de concordância de 99%. o instrumento foi validado com quatro domínios (Vínculo, Autonomia, Acolhimento e Gestão) e dezenove itens que avaliam o uso das tecnologias leves em Unidade de Terapia Intensiva. construir y validar un instrumento para evaluación del uso de tecnologías leves, por el equipo de enfermería, en Unidades de Terapia Intensiva. estudio metodológico en el cual el instrumento fue elaborado utilizando el método psicométrico para construcción con base en la categorización de las tecnologías en salud de Merhy y Franco, de la Política Nacional de Humanización, la que utilizó la taxonomía Nursing Intervention Classification para categorizar los dominios del instrumento. Para la validación se utilizó el Porcentaje de Concordancia y el Índice de Validez de Contenido (IVC). el resultado de la aplicación del Porcentaje de Concordancia entre los jueces fue superior al recomendado de 80%, destacándose la evaluación de la pertinencia al tema propuesto, presentando un porcentaje de concordancia de 99%. el instrumento fue validado en cuatro dominios (Vínculo, Autonomía, Acogimiento y Administración) y con diecinueve ítems que evalúan el uso de las tecnologías leves en Unidad de Terapia Intensiva.

Determinacion de periodos fundamentales del suelo mediante vibraciones ambientales en el municipio de Humacao, Puerto Rico

NASA Astrophysics Data System (ADS)

Cintron Aponte, Rommel

La tecnica de Nakamura ha sido utilizada a nivel mundial para determinar periodos fundamentales del suelo. La tecnica consiste en calcular y graficar cocientes espectrales H/V de vibraciones ambientales registradas sobre el suelo. Mediciones de vibraciones ambientales fueron tomadas en 151 lugares dentro del municipio de Humacao, localizado al este de Puerto Rico. Los datos se procesaron utilizando espectros de Fourier y espectros de potencia. La tecnica fue validada al compararla con los resultados de cocientes espectrales H/V de registros de sismos debiles y tambien con una modelacion numerica realizada con datos de un ensayo "downhole". Las graficas de los cocientes espectrales H/V fueron divididas en casos y grupos, los cuales dependen de la facilidad para identificar el periodo fundamental pico y amplitudes en frecuencias menores de 1 Hz, respectivamente. Los resultados obtenidos con ambos espectros fueron comparados y se concluye que los mismos se complementan para proveer resultados mas confiables. Se crearon mapas de periodos fundamentales, factores de amplitud, isoperiodos y clasificacion sismica de sitio. Los mapas de isoperiodos fueron realizados en las zonas mas pobladas sobre depositos de suelo. El mapa de periodos fundamentales del suelo mostro buena correlacion con la geologia local. El mapa de clasificacion sismica derivado de periodos de sitio fue comparado con el mapa de clasificacion sismica derivado de barrenos geotecnicos. El mapa de clasificacion obtenido de periodos puede sobreestimar un poco algunas clasificaciones del suelo. Sin embargo, este mapa puede proveer un estimado aproximado de la velocidad de onda de corte promedio del suelo hasta una profundidad de 100 pies (30 metros).

Social support of adults and elderly with chronic kidney disease on dialysis.

PubMed

Silva, Simone Márcia da; Braido, Natalia Fernanda; Ottaviani, Ana Carolina; Gesualdo, Gabriela Dutra; Zazzetta, Marisa Silvana; Orlandi, Fabiana de Souza

2016-08-08

to evaluate the instrumental and emotional social support of patients with chronic kidney disease on hemodialysis. descriptive cross-sectional study. The sample was sized for convenience and included 103 participants under treatment in a Renal Replacement Therapy Unit. Data were collected through individual interviews, using the Social Support Scale. the mean scores of the emotional and instrumental social support were 3.92 (± 0.78) and 3.81 (± 0.69) respectively, an indication of good support received. The most frequent sources of instrumental and emotional social support mentioned by participants were partners, spouse, companion or boyfriend and friends. patients with chronic kidney disease have high social support, both instrumental and emotional, and the main support comes from the family. avaliar o suporte social instrumental e emocional de pacientes renais crônicos em tratamento hemodialítico. estudo descritivo, de corte transversal. A amostra dimensionada por conveniência foi composta por 103 participantes em tratamento em uma Unidade de Terapia Renal Substitutiva. Os dados foram coletados por meio de entrevista individual, utilizando-se a Escala de Suporte Social. o escore médio do suporte social emocional e instrumental foi de 3,92 (±0,78) e foi 3,81 (± 0,69) respectivamente, sendo um indicativo de bom suporte recebido. Entre as fontes mais frequentes de suporte social instrumental e emocional mencionadas pelos participantes encontram-se os parceiros, cônjuge, companheiro ou namorado e amigos. os pacientes com doença renal crônica apresentam elevado apoio social, tanto instrumental quanto emocional, sendo a principal forma de apoio proveniente da família. evaluar el apoyo social instrumental y emocional de los enfermos renales crónicos en hemodiálisis. estudio descriptivo, de cohorte transversal. La muestra ha sido dimensionada por conveniencia y compuesta de 103 participantes en tratamiento en una Unidad de Terapia de Reemplazo Renal. Los datos se recopilaron mediante entrevista individual, utilizando la Escala de Apoyo Social. la puntuación media del apoyo social emocional e instrumental fue de 3,92 (± 0,78) y 3,81 (± 0,69), respectivamente, lo que indica un buen apoyo recibido. Entre las fuentes más frecuentes de apoyo social instrumental y emocional mencionadas por los participantes figuran pareja, cónyuge, compañero o novio y amigos. los pacientes con enfermedad renal crónica tienen un fuerte apoyo social, tanto instrumental como emocional, y la principal forma de apoyo proviene de la familia.

Fotometría UBVI en NGC 6231

NASA Astrophysics Data System (ADS)

Baume, G. L.; Vázquez, R. A.; Feinstein, A.

Se ha realizado fotometría CCD UBVI en la zona del cúmulo abierto NGC 6231, habiéndose observado 1062 estrellas hasta una magnitud V≈ 19. Esto posibilita tener una imagen clara de la parte inferior de la secuencia principal del cúmulo. Combinando nuestros datos con tipos espectrales tomados de la literatura pudimos re-derivar la ley de absorción en dirección a este cúmulo y encontrar que los valores de R muestran variaciones de estrella a estrella. La secuencia principal inferior muestra también algunos rasgos intrigantes: hay un codo notorio en V≈ 13.5 seguido por un gran ``spread'' de magnitudes a color constante entre las estrellas débiles y una inusualmente alta densidad de estrellas a lo largo de una banda que se extiende 1.5 mag encima de la ZAMS. Los cálculos indican que el número esperado de estrellas de campo en dirección al cúmulo debería ser menor que el observado. Una re-evaluación de las funciones de luminosidad y masa dentro de los límites -7.5 < MV < 1.5 mag y 2 Msolar < M arroja pendientes planas para ambas funciones, lo que parece ser típico de cúmulos muy jóvenes. Todos estos rasgos son congruentes con un escenario joven donde las estrellas en fase de contracción están arribando a la secuencia principal.

Prevalence of hypoalbuminemia and nutritional issues in hospitalized elders.

PubMed

Brock, Felipe; Bettinelli, Luiz Antonio; Dobner, Taise; Stobbe, Júlio César; Pomatti, Gabriela; Telles, Cristina Trevizan

2016-08-08

to estimate the prevalence of hypoalbuminemia in hospitalized elders, related to socio-demographic variables, nutritional status and length of stay. crosscutting study with 200 patients hospitalized in a large hospital in the South of Brazil during three months. Evaluations, lab tests and interviews through questionnaires were performed. the average albuminemia was 2,9 ± 0,5g/dL. Hypoalbuminemia was diagnosed in 173 subjects (87%) and was absent in 27 (13%) that have normal albuminemia (p=0,000). After six days of hospitalization, the prevalence of low levels grew significantly to 90% (p=0,002), average 2,7 ± 0,5g/dL. Using the Mini Nutritional Assessment, it was observed that 41 patients were malnourished and from those, 40 had hypoalbuminemia. the prevalence of hypoalbuminemia proved to be high, in approx. nine in ten elders, and the nutritional status and the length of stay proved to be related to the decrease of serum albumin levels. Thus, it is suggested that monitoring albumin levels should be done to evaluate the risk that the patient has to develop malnutrition and other complications during hospital stays. estimar a prevalência de hipoalbuminemia em idosos hospitalizados, em relação às variáveis sociodemográficas, estado nutricional e tempo de internação. estudo transversal, com 200 pacientes internados em hospital de grande porte do sul do Brasil, durante o período de três meses. Foram realizadas avaliações, análise de exames laboratoriais e entrevista através de questionário. a média de albuminemia foi 2,9 ± 0,5g/dL. O diagnóstico de hipoalbuminemia, foi encontrado em 173 sujeitos (87%), e não revelado em 27 (13%), que apresentaram albuminemia normal (p=0,000). Constatou-se que após seis dias de internação a prevalência de níveis baixos aumentou significativamente para 90% (p=0,002), com média de 2,7 ± 0,5g/dL. Utilizando-se a Mini Avaliação Nutricional, observou-se que 41 pacientes estavam desnutridos, e que destes, 40 apresentavam hipoalbuminemia. a prevalência de hipoalbuminemia mostrou-se elevada, acometendo aproximadamente nove entre dez idosos, sendo que o estado nutricional, da mesma maneira que o tempo de internação , está relacionado à diminuição dos níveis de albumina sérica. Assim, sugere-se monitorar os níveis de albuminemia para avaliar o risco que o paciente tem de desenvolver desnutrição e demais complicações durante a internação hospitalar. estimar la prevalencia de hipoalbuminemia en ancianos hospitalizados, considerando las variables sociodemográficas, estado nutricional y tiempo de internación. estudio transversal, en 200 pacientes internados en hospital de gran porte del sur de Brasil, durante un período de tres meses. Fueron realizadas evaluaciones, análisis de exámenes de laboratorio y se realizó una entrevista usando un cuestionario. el promedio de albuminemia fue 2,9 ± 0,5g/dL. El diagnóstico de hipoalbuminemia, fue encontrado en 173 sujetos (87%), y no revelado en 27 (13%), que presentaron albuminemia normal (p=0,000). Se constató que después de seis días de internación la prevalencia de niveles bajos aumentó significativamente para 90% (p=0,002), con promedio de 2,7 ± 0,5g/dL. Utilizando la Mini Evaluación Nutricional, se observó que 41 pacientes estaban desnutridos, y que de estos, 40 presentaban hipoalbuminemia. la prevalencia de hipoalbuminemia se mostró elevada, afectando aproximadamente nueve entre diez ancianos, siendo que el estado nutricional, de la misma manera que el tiempo de internación, está relacionado a la disminución de los niveles de albúmina sérica. Así, se sugiere monitorizar los niveles de albuminemia para evaluar el riesgo que el paciente tiene de desarrollar desnutrición y demás complicaciones durante la internación hospitalaria.

Critical thinking: concept analysis from the perspective of Rodger's evolutionary method of concept analysis.

PubMed

Carbogim, Fábio da Costa; Oliveira, Larissa Bertacchini de; Püschel, Vilanice Alves de Araújo

2016-09-01

to analyze the concept of critical thinking (CT) in Rodger's evolutionary perspective. documentary research undertaken in the Cinahl, Lilacs, Bdenf and Dedalus databases, using the keywords of 'critical thinking' and 'Nursing', without limitation based on year of publication. The data were analyzed in accordance with the stages of Rodger's conceptual model. The following were included: books and articles in full, published in Portuguese, English or Spanish, which addressed CT in the teaching and practice of Nursing; articles which did not address aspects related to the concept of CT were excluded. the sample was made up of 42 works. As a substitute term, emphasis is placed on 'analytical thinking', and, as a related factor, decision-making. In order, the most frequent preceding and consequent attributes were: ability to analyze, training of the student nurse, and clinical decision-making. As the implications of CT, emphasis is placed on achieving effective results in care for the patient, family and community. CT is a cognitive skill which involves analysis, logical reasoning and clinical judgment, geared towards the resolution of problems, and standing out in the training and practice of the nurse with a view to accurate clinical decision-making and the achieving of effective results. analisar o conceito de pensamento crítico (PC), na perspectiva evolucionista de Rodgers. pesquisa documental realizada nas bases de dados Cinahl, Lilacs, Bdenf e Dedalus, utilizando-se as palavras-chave pensamento crítico e Enfermagem, sem delimitação de ano de publicação. Os dados foram analisados conforme etapas do modelo conceitual de Rodgers. Incluíram-se livros e artigos na íntegra, publicados em português, inglês ou espanhol que abordavam o PC no ensino e prática de Enfermagem, excluindo-se estudos que não abordassem aspectos relacionados ao conceito do PC. a amostra foi constituída por 42 trabalhos. Como termo substituto, destacou-se pensamento analítico e, como fator relacionado, tomada de decisão. Pela ordem, os atributos, antecedentes e consequentes mais frequentes, foram: capacidade de análise, formação do estudante de enfermagem e tomada de decisão clínica. Como implicação do PC, destaca-se o alcance de resultados efetivos na assistência ao paciente, família e comunidade. o PC é uma habilidade cognitiva que envolve análise, raciocínio lógico e julgamento clínico, orientado para resolução de problemas e destacando-se na formação e prática do enfermeiro com vistas à tomada de decisão clínica acurada e alcance de resultados efetivos. analizar el concepto de Pensamiento Crítico (PC), en la perspectiva evolucionista de Rodgers. investigación documental realizada en las bases de datos Cinahl, Lilacs, Bdenf y Dedalus, utilizando las palabras clave pensamiento crítico y Enfermería, sin delimitación de año de publicación. Los datos fueron analizados conforme etapas del modelo conceptual de Rodgers. Se incluyeron libros y artículos completos, publicados en portugués, inglés o español, que abordaban el PC en la enseñanza y práctica de Enfermería, excluyendo estudios que no abordasen aspectos relacionados al concepto del PC. la muestra estuvo constituida por 42 trabajos. Como término sustituto, se destacó el pensamiento analítico y, como factor relacionado la toma de decisiones. Por orden, los atributos, antecedentes y consecuentes más frecuentes, fueron: capacidad de análisis, formación del estudiante de enfermería y toma de decisiones clínicas. Como implicación del PC, se destaca el alcance de resultados efectivos en la asistencia al paciente, familia y comunidad. el PC es una habilidad cognitiva que envuelve análisis, raciocinio lógico y juzgamiento clínico, es orientado para la resolución de problemas y se destaca en la formación y práctica del enfermero, objetivando la toma de decisiones clínicas precisas y la obtención de resultados efectivos.

Genes del receptor variable beta de células T en células circulantes de pacientes con lupus eritematoso generalizado y sus familiares sanos.

PubMed

Jakez-Ocampo, Juan; Paulín-Vera, Carmen María; Rivadeneyra-Espinoza, Liliana; Gómez-Martín, Diana; Carrillo-Maravilla, Eduardo; Lima, Guadalupe; Vargas-Rojas, María Inés; Pérez-Romano, Beatriz; Calva-Cevenini, Gabriella; García-Carrasco, Mario; Ruiz-Argüelles, Alejandro; Llorente, Luis

Se investigó la proporción de la expresión génica del receptor variable beta de células T (Vβ TCR) en linfocitos periféricos CD3+ en pacientes con lupus eritematoso generalizado (LEG) familiar y no familiar. El repertorio de Vβ TCR se estudió en 14 familias que presentaban más de un miembro con LEG. El uso de Vβ TCR en pacientes con LEG (n = 27) se comparó con el de los miembros sanos de estas familias (n = 47), con 37 pacientes con LEG esporádico y con 15 controles sanos. La expresión del repertorio de Vβ TCR se estudió por citometría de flujo multiparamétrica utilizando un arreglo de 24 diferentes anticuerpos monoclonales específicos de genes familiares para Vβ TCR. Se encontró el mismo perfil de expresión en las comparaciones entre los casos de LEG esporádico y familiar, así como en los consanguíneos sanos de las familias multicasos, que incluía una expresión incrementada de Vβ 5.2, Vβ 11 y Vβ 16, y una menor expresión de Vβ 3, Vβ4, Vβ 7.1 y Vβ 7. De manera interesante, solo Vβ 17 se expresó de modo diferente entre casos familiares y esporádicos de LEG. Igualmente, la expresión incrementada de Vβ 9 fue el distintivo entre los casos de LEG familiar (casos y consanguíneos sanos) y los controles sanos. Estos resultados refuerzan la noción de que el perfil final del repertorio Vβ TCR observado en LEG familiar y no familiar parece surgir de la interacción de factores genéticos, ambientales e inmunorreguladores, además de que pueden explicar las alteraciones inmunitarias que se observan en los consanguíneos sanos de pacientes con LEG. Copyright: © 2018 SecretarÍa de Salud

Presentación del estudio “Links” de hombres que tienes sexo con hombres en Buenos Aires, Argentina

PubMed Central

Carballo-Diéguez, Alex; Ávila, María M; Balán, Iván C.; Marone, Rubén; Pando, María A.; Barreda, Victoria

2011-01-01

Resumen Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos (“teteras”), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA. PMID:25264397

Evolución de planetas gigantes y posibilidades de su detección directa

NASA Astrophysics Data System (ADS)

Brunini, A.; Benvenuto, O. G.

Desde la reciente detección de planetas gigantes orbitando estrellas cercanas de tipo solar por medio de efecto Doppler, uno de los principales problemas, en cuanto al estudio de los sistemas planetarios extrasolares, se refiere a la posibilidad de obtener evidencia directa de su existencia. Esto parece ser factible gracias a que en un futuro cercano entrarán en operación algunos telescopios especialmente adecuados a estos propósitos. Por tal motivo, hemos comenzado desde hace un tiempo un esfuerzo en cuanto al estudio de la evolución planetaria. A tales efectos hemos adaptado el código de evolución estelar de nuestro Observatorio al caso planetario. Las principales diferencias entre el caso estelar y el planetario se encuentran en la ecuación de estado. A tales fines hemos incluído la reciente ecuación de estado de Saumon, Chabrier y Van Horn, las opacidades radiativas de Guillot et al., procesos de quema de Deuterio, etc. También se ha considerado la posible existencia de fases de hielo y roca en el interior planetario. Por el momento hemos despreciado los efectos de la rotación planetaria. Con este código hemos computado la evolución de planetas con masas desde 10 hasta 0.3 masas de Júpiter. Utilizando nuestros resultados numéricos discutimos la detectabilidad de estos objetos en condiciones realistas.

Obstáculos a la adherencia y retención en los sistemas de salud público y privado según pacientes y personal de salud

PubMed Central

Arístegui, Inés; Dorigo, Analía; Bofill, Lina; Bordatto, Alejandra; Lucas, Mar; Cabanillas, Graciela Fernández; Sued, Omar; Cahn, Pedro; Cassetti, Isabel; Weiss, Stephen; Jones., Deborah

2016-01-01

Resumen Introducción el Programa Nacional de Sida garantiza el acceso universal a los antirretrovirales, aun así las personas que reciben medicamentos a través del sistema público no logran obtener una carga viral indetectable en la misma proporción que los pacientes del sistema privado. Este estudio cualitativo tiene como objeto identificar los factores asociados a la adherencia y retención en la cascada de atención de VIH de los sistemas de salud público y privado de Buenos Aires, según las percepciones de pacientes y del personal de salud. Métodos se registraron datos cualitativos de 12 entrevistas semi-estructuradas a informantes clave y 4 grupos focales de pacientes y personal de salud tanto del sistema público como privado. Se codificaron y analizaron temas predeterminados sobre adherencia, utilizando el software QRS Nvivo9® de análisis de datos cualitativos. Resultados pacientes y personal de salud de ambos sistemas coinciden en la importancia del estigma asociado al VIH, la relación médicopaciente, la comunicación entre ambos y la división de responsabilidades en relación al tratamiento como aspectos fundamentales para la adherencia y retención en la cascada de atención. Se observan diferencias entre los sistemas en la forma en que algunos de estos aspectos actúan. Las barreras estructurales se presentan como principales obstáculos del sistema público. Discusión se resalta la necesidad de intervenciones focalizadas en la díada médico-paciente que considere las particularidades de cada sistema de atención para facilitar el compromiso del paciente en la adherencia. PMID:26878024

Association between poor clinical prognosis and sleep duration among breast cancer patients.

PubMed

Mansano-Schlosser, Thalyta Cristina; Ceolim, Maria Filomena

2017-06-05

to investigate the association between clinical progression and the quality and duration of sleep in women with breast cancer. longitudinal study, with 114 participants, conducted in a hospital in Brazil. The instruments used were: questionnaire for sociodemographic and clinical characterization, Pittsburgh Sleep Quality Index; Beck Depression Inventory and Herth Hope Scale. Data were analyzed through descriptive statistics and survival analyses (outcome: poor clinical progression), using the Kaplan-Meier curve, Log-rank test and Cox proportional model. a higher probability of poor clinical progression was verified in women with sleep durations of less than six hours or nine hours and over (p=.0173). the results suggest the importance of further studies that seek to verify whether the quantitative management of sleep disorders would have an impact on the progression of breast cancer. Women should be encouraged to report sleep problems to nurses. mensurar a associação entre evolução clínica e qualidade e duração do sono em mulheres com câncer de mama. estudo longitudinal, com 114 participantes, realizado em um hospital do Brasil. Os instrumentos utilizados foram: questionário para caracterização sociodemográfica e clínica, Índice de Qualidade do Sono de Pittsburgh; Inventário de Depressão de Beck e Escala de Esperança de Herth. Os dados foram analisados via análises descritivas e de sobrevivência (resultado: evolução clínica desfavorável), utilizando-se a curva de Kaplan-Meier, o teste log-rank e o modelo proporcional de Cox. verificou-se maior probabilidade de evolução clínica desfavorável em mulheres com duração de sono inferior a seis ou mais de nove horas (p = 0,0173). os resultados sugerem a importância de mais estudos que buscam verificar se a gestão quantitativa dos distúrbios do sono teria um impacto sobre a evolução do câncer de mama. As mulheres devem ser encorajadas a relatar isso espontaneamente aos enfermeiros. medir la asociación entre progresión clínica y calidad y duración del sueño en mujeres con cáncer de mama. estudio longitudinal, con 114 participantes, realizado en un hospital de Brasil. Los instrumentos utilizados fueron: cuestionario para caracterización sociodemográfica y clínica; índice de calidad del sueño de Pittsburgh; Inventario de Depresión de Beck; y Escala de esperanza de Herth. Los datos se analizaron a través de análisis descriptivo y de supervivencia (resultado: evolución clínica desfavorable), utilizando la curva de Kaplan-Meier, la prueba log-rank y el modelo proporcional de Cox. se comprobó una mayor probabilidad de progresión clínica desfavorable en mujeres con duración de sueño inferior a seis horas o más de nueve horas (p = 0,0173). los resultados sugieren la importancia de realizar más estudios que busquen verificar si la gestión cuantitativa de los trastornos del sueño tendría un impacto en la progresión del cáncer de mama. Las mujeres deben ser alentadas a informar esto espontáneamente a las enfermeras.

Alfabetización en Astronomía de docentes de Educación Primaria y de Educación Secundaria en La Plata

NASA Astrophysics Data System (ADS)

De Biasi, M. S.; Orellana, R. B.

2014-10-01

La educación de este siglo tiene como uno de sus retos alcanzar la alfabetización cientfica de todos los ciudadanos para que comprendan y tomen decisiones sobre el mundo natural y sus cambios originados por la actividad humana utilizando el conocimiento científico. En esta misión los docentes de los niveles obligatorios de enseñanza juegan un papel clave por su rol de agentes multiplicadores del conocimiento. Se requiere, entonces de una adecuada alfabetización en ciencias de los docentes o, como mínimo, que dominen los temas científicos a enseñar. En el campo de la Astronomía, numerosas investigaciones han señalado que maestros de primaria y estudiantes de profesorados poseen una escasa formación en estos temas (Camino 1995 y 1999, Gangui 2010), que frecuentemente presentan a los alumnos concepciones alternativas o no científicas de los fenómenos astronómicos cotidianos (Kriner 2004, Vega Navarro 2007, Gangui et al 2010); a lo que se suma la presentación confusa o errónea de algunos temas astronómicos en los textos escolares (Kriner 2004). Desde 2011, la Facultad de Ciencias Astronómicas y Geofísicas, UNLP, ofrece un curso de capacitación destinado a fortalecer y actualizar los contenidos académicos y didácticos de los docentes del distrito La Plata utilizando diversas estrategias didácticas. Los contenidos comprenden los temas astronómicos de los diseños curriculares vigentes. La evaluación diagnóstica de los conocimientos previos de los docentes cursantes sobre los contenidos de mayor presencia en los diseños curriculares mostró resultados similares a las investigaciones arriba mencionadas. Referente a los movimientos de la Tierra, en promedio, el 54% poseía conceptos erróneos y el 16% no los sabía; con referencia a la Luna el 56% poseía conceptos erróneos y un 4% no los sabía. Los resultados del curso mostraron que el 95% de los docentes revirtió sus conceptos previos erróneos, que adquirió criterios para la búsqueda de fuentes de información confiables y que el grado de conocimientos disciplinares y didácticos alcanzados por los docentes garantiza el efecto multiplicador de esta propuesta. Esta capacitación fue acreditada con puntaje por el organismo educativo provincial en 2011, 2012 y 2013.

Precessão do jato de 3C120: simulações hidrodinâmicas 3D

NASA Astrophysics Data System (ADS)

Caproni, A.; de Gouveia dal Pino, E. M.; Abraham, Z.; Raga, A. C.

2003-08-01

Observações com técnicas de interferometria com longa linha de base têm mostrado a existência de um jato relativístico com componentes superluminais na região central de 3C 120. Estas componentes são ejetadas em distintas direções no plano do céu e com diferentes velocidades aparentes. Estas características foram interpretadas em trabalhos anteriores como efeitos da precessão do jato relativístico. Neste trabalho, realizamos simulações tri-dimensionais do jato de 3C 120 utilizando os parâmetros de precessão determinados em trabalhos anteriores e variando as características iniciais do jato e meio ambiente, tais como densidade numérica e temperatura. Todas as simulações foram feitas com o código hidrodinâmico YGUAZÚ-A, assumindo-se um jato adiabático descrito por uma equação de estado relativística. Pelo fato de estarmos utilizando um código hidrodinâmico, nós assumimos que a intensidade do campo magnético e a distribuição de partículas, necessários para se calcular a emissão sincrotron, são proporcionais à pressão hidrodinâmica. Comparação entre dois cenários distintos, nos quais o material do jato é ejetado com velocidade constante (jato contínuo) e com velocidade modulada por um padrão sinusoidal no tempo (jato intermitente), é apresentada e discutida. Para jatos que apresentam fenômenos de precessão e intermitência, com amplitude de variação na velocidade de injeção maior que dez por cento da velocidade média de injeção, a hipótese balística, controlada pela intermitencia, é mais provável. Por outro lado, para jatos com precessão mas sem intermitência (ou com amplitude de variabilidade em velocidade mais baixa que no caso anterior), o efeito da precessão na morfologia do jato não é desprezível. Portanto, de um modo geral, ambos efeitos (precessão e movimentos balísticos) devem estar concorrendo para afetar a morfologia dos jatos superluminais.

Imagens de Leitura na Literatura de Cordel (Images of Reading in "Cordel" Literature).

ERIC Educational Resources Information Center

Hata, Luli

1997-01-01

Shows, in "Cordel" literature (a popular manifestation found in northeastern Brazil) an expressive source for the analysis of popular culture in Brazil. Uses this literature to discuss images of reading. (PA)

Spatial distribution of tuberculosis in a municipality in the interior of São Paulo, 2008-2013.

PubMed

Fusco, Alcione Pereira Biffi; Arcêncio, Ricardo Alexandre; Yamamura, Mellina; Palha, Pedro Fredemir; Reis, Amanda Alessandra Dos; Alecrim, Tatiana Ferraz de Araújo; Protti, Simone Teresinha

2017-06-05

to describe the epidemiological clinical profile of tuberculosis and analyze the spatial distribution of cases in a municipality in the state of São Paulo. descriptive and ecological study of cases of tuberculosis through the records in an information system. Descriptive statistics were used to calculate central tendency (mean) and chi-square test, with Yates correction or Fisher exact test, when necessary. The Kernel technique was also used to calculate the occurrence densities of tuberculosis cases, using a radius of 1000 meters. Type I error was set at 5%. 299 cases of tuberculosis were identified, with 290 (96.98%) being geocoded. The majority of these were male (n = 212; 70.91%), median age 40 years, and the pulmonary clinical form was predominant (n = 244, 81.60%). The distribution occurred in a non-random manner, observing important areas of the municipality with a higher density of cases of the disease. the study evidenced an epidemiological profile of tuberculosis cases similar to those in the literature; however, their distribution does not occur in a random manner, pointing to specific population groups that require greater management and planning of health services for the control of tuberculosis. caracterizar o perfil clínico epidemiológico da tuberculose (TB) e analisar a distribuição espacial dos casos em município paulista. estudo descritivo e ecológico dos casos de tuberculose registrados em um sistema de informação. Recorreu-se à estatística descritiva com cálculo de medidas de tendência central (média) e aplicação do teste qui-quadrado, com correção de Yates ou teste exato de Fisher, quando necessários. Aplicou-se ainda a técnica de Kernel para o cálculo das densidades de ocorrência dos casos da TB, utilizando um raio de 1000 metros. Fixou-se o erro tipo I em 5%. identificou-se 299 casos de TB, sendo geocodificados 290 (96,98%). A maioria destes foi do sexo masculino (n=212; 70,91%), idade mediana 40 anos, sendo a forma clínica pulmonar predominante (n=244; 81,60%). A distribuição ocorreu de forma não aleatória, observando-se áreas importantes do município com maior densidade de casos da doença. o estudo evidenciou perfil epidemiológico dos casos de tuberculose semelhante ao da literatura, no entanto, a distribuição dos mesmos não ocorre de forma aleatória, apontando grupos específicos da população que necessitam de maior gestão e planejamento dos serviços de saúde para o controle da tuberculose. caracterizar el perfil epidemiológico clínico de tuberculosis y analizar la distribución espacial de casos en un municipio paulista. Estudio descriptivo y ecológico de casos de tuberculosis registrados en un sistema de información. Se utilizó estadística descriptiva con medidas de tendencia central (media) y aplicación de chi-cuadrado, con correlación de Yates o prueba exacta de Fisher según necesidad. Para el calcular la densidad en la ocurrencia de casos de tuberculosis, se aplicó la técnica uniforme Kernel utilizando una distancia de 1000 metros. El error de tipo I fue fijado en 5%. Se identificaron 299 casos de tuberculosis, siendo geocodificados 290 (96.98%). La mayoría de los casos fueron de sexo masculino (n=212; 70,91%), con edad mediana de 40 años, siendo la forma pulmonar la más predominante (n=244; 81,60%). La distribución de casos fue forma no aleatoria, identificando áreas del municipio con mayor densidad de casos con esta patología. el perfil epidemiológico de casos de tuberculosis observado fue similar a lo observado en la literatura, aunque la distribución de estos no ocurre de manera aleatoria, identificando grupos específicos de la población los cuales requieren de mayores gestión y planificación en los servicios de salud para el control de la tuberculosis.

Patient Safety Incidents and Nursing Workload.

PubMed

Carlesi, Katya Cuadros; Padilha, Kátia Grillo; Toffoletto, Maria Cecília; Henriquez-Roldán, Carlos; Juan, Monica Andrea Canales

2017-04-06

to identify the relationship between the workload of the nursing team and the occurrence of patient safety incidents linked to nursing care in a public hospital in Chile. quantitative, analytical, cross-sectional research through review of medical records. The estimation of workload in Intensive Care Units (ICUs) was performed using the Therapeutic Interventions Scoring System (TISS-28) and for the other services, we used the nurse/patient and nursing assistant/patient ratios. Descriptive univariate and multivariate analysis were performed. For the multivariate analysis we used principal component analysis and Pearson correlation. 879 post-discharge clinical records and the workload of 85 nurses and 157 nursing assistants were analyzed. The overall incident rate was 71.1%. It was found a high positive correlation between variables workload (r = 0.9611 to r = 0.9919) and rate of falls (r = 0.8770). The medication error rates, mechanical containment incidents and self-removal of invasive devices were not correlated with the workload. the workload was high in all units except the intermediate care unit. Only the rate of falls was associated with the workload. identificar a relação entre a carga de trabalho da equipe de enfermagem e a ocorrência de incidentes de segurança dos pacientes ligados aos cuidados de enfermagem de um hospital público no Chile. pesquisa transversal analítica quantitativa através de revisão de prontuários médicos. A estimativa da carga de trabalho em Unidade de Terapia Intensiva (UTI) foi realizada utilizando o Índice de Intervenções Terapêuticas-TISS-28 e para os outros serviços, foram utilizados os cocientes enfermeira/paciente e auxiliar de enfermagem/ paciente. Foram feitas análises univariada descritiva e multivariada. Para a análise multivariada utilizou-se análise de componentes principais e correlação de Pearson. foram analisados 879 prontuáriosclínicos de pós-alta e a carga de trabalho de 85 enfermeiros e 157 auxiliares de enfermagem. A taxa global de incidentes foi de 71,1%. Foi encontrada uma alta correlação positiva entre as variáveis de carga de trabalho (r = 0,9611 para r = 0,9919) e a taxa de quedas (r = 0,8770). As taxas de erro de medicação, incidentes de contenção mecânica e auto remoção de dispositivos invasivos não foram correlacionadas com a carga de trabalho. a carga de trabalho foi elevada em todas as unidades, exceto na unidade de cuidados intermédios. Apenas a taxa de quedas foi associada com a carga de trabalho. identificar la relación entre la carga laboral del equipo de enfermería y la ocurrencia de incidentes de seguridad del paciente relacionados con los cuidados de enfermería en un hospital público de Chile. investigación cuantitativa, analítica, transversal, realizada por revisión de fichas clínicas. La estimación de carga laboral en las Unidades de Cuidados Intensivos (UCI) se realizó utilizando el Índice de Intervenciones Terapéuticas (TISS-28) y, para el resto de los servicios, por la relación enfermera/paciente y auxiliar/paciente. Se realizó análisis descriptivo univariado y multivariado. Para el análisis multivariado se utilizó análisis de componentes principales y el test de correlación de Pearson. se revisaron 879 fichas clínicas posteriores al alta y la carga laboral de 85 enfermeras y 157 auxiliares de enfermería. La tasa global de incidentes fue 71,1%. Se encontró correlación positiva alta entre las variables de carga laboral (r = 0,9611 a r = 0,9919) y tasa de caídas (r = 0,8770). Las tasas de error de medicación, incidente por contención mecánica y auto retiro de invasivos no se correlacionaron con la carga laboral. la carga laboral fue elevada en todas las unidades a excepción de la unidad de cuidados intermedios. Sólo la tasa de caídas se asoció a la carga laboral.

Factors associated with young adults' knowledge regarding family history of Stroke.

PubMed

Lima, Maria Jose Melo Ramos; Moreira, Thereza Maria Magalhães; Florêncio, Raquel Sampaio; Braga, Predro

2016-11-21

to analyze the factors associated with young adults' knowledge regarding family history of stroke. an analytical transversal study, with 579 young adults from state schools, with collection of sociodemographic, clinical and risk factor-related variables, analyzed using logistic regression (backward elimination). a statistical association was detected between age, civil status, and classification of arterial blood pressure and abdominal circumference with knowledge of family history of stroke. In the final logistic regression model, a statistical association was observed between knowledge regarding family history of stroke and the civil status of having a partner (ORa=1.61[1.07-2.42]; p=0.023), abdominal circumference (ORa=0.98[0.96-0.99]; p=0.012) and normal arterial blood pressure (ORa=2.56[1.19-5.52]; p=0.016). an association was observed between socioeconomic factors and risk factors for stroke and knowledge of family history of stroke, suggesting the need for health education or even educational programs on this topic for the clientele in question. analisar os fatores associados ao conhecimento dos adultos jovens sobre histórico familiar de Acidente Vascular Cerebral (AVC). estudo transversal analítico, com 579 adultos jovens de escolas públicas, com coleta de variáveis sociodemográficas, clínicas e de fatores de risco em formulário, analisados utilizando-se regressão logística (backward elimination). detectou-se associação estatística de idade, situação conjugal, classificação da pressão arterial e circunferência abdominal com conhecimento do histórico familiar de AVC. No modelo final de regressão logística, observou-se associação estatística do conhecimento sobre histórico familiar de AVC com situação conjugal com companheiro (ORa=1,61[1,07-2,42]; p=0,023), circunferência abdominal (ORa=0,98[0,96-0,99]; p=0,012) e pressão arterial normal (ORa=2,56[1,19-5,52]; p=0,016). foi constatada associação de fatores socioeconômicos e de risco para AVC com o conhecimento do histórico familiar de AVC, sugerindo a necessidade de educação em saúde ou mesmo de programas educacionais sobre o tema junto à clientela em estudo. analizar los factores asociados al conocimiento de los adultos jóvenes sobre el histórico familiar de Accidente Vascular Cerebral (AVC). estudio transversal analítico en 579 adultos jóvenes de escuelas públicas, con recolección de variables sociodemográficas, clínicas y de factores de riesgo en formulario, los datos fueron analizados utilizando la regresión logística (backward elimination). se detectó asociación estadística de edad, situación conyugal, clasificación de la presión arterial y circunferencia abdominal con el conocimiento del histórico familiar de AVC. En el modelo final de regresión logística, se observó una asociación estadística del conocimiento sobre el histórico familiar de AVC con: situación conyugal con compañero (ORa=1,61[1,07-2,42] p=0,023); circunferencia abdominal (ORa=0,98[0,96-0,99] p=0,012); y presión arterial normal (ORa=2,56[1,19-5,52] p=0,016). fue constatada asociación de factores socioeconómicos y de riesgo para AVC con el conocimiento del histórico familiar de AVC; se sugiere la necesidad de realizar acciones de educación en salud o inclusive de preparar programas educacionales sobre el tema para la población estudiada.

PubMed

Defagó, Victor

2017-10-10

Introducción: La incorporación de la Clínica y la Imagenología permiten una mejor comprensión de la Anatomía. El objetivo de este trabajo es desarrollar un prototipo rápido en material sintético que replique detalles anatómicos para ser utilizado en la docencia y el entrenamiento quirúrgico en Pediatría.Material y Método: Presentación de caso: Paciente de un año de edad con síndrome de dificultad respiratoria. En el examen endoscópico se halló una compresión traqueal distal. La angiotomografía confirmó la presencia de una malformación vascular. Con la finalidad de analizar una conducta adecuada, se solicitó la confección de un prototipo rápido a escala 1:1 que simulara una condición idéntica a la topografía torácica del paciente, utilizando imágenes virtuales 3D almacenadas en formato DICOM.Técnica de generación de prototipo rápido: Se obtuvo una malla digital tridimensional y se generó el código "g" que se utilizó para controlar el hardware de producción. Se efectuó simulación digital y producción en material plástico (ABS) con técnica de deposición y fusión (MDF). Se validó el prototipo comparándolo con las mediciones testigos del modelo virtual en 3 D.Resultados y Discusión: El modelo replicó exactamente los defectos hallados en la tomografía y endoscopía, confirmando la presencia de la malformación vascular y su repercusión sobre el aparato respiratorio. El prototipo rápido muestra las estructuras internas y externas del cuerpo humano con máxima precisión permitiendo una visión topográfica de situaciones "normales o patológicas" que facilitaría la docencia y el entrenamiento del equipo quirúrgico para proponer un plan de tratamiento adecuado. Hay numerosas áreas de la medicina que se beneficiarían con este modelo que podría ser construído con diversos tipos de materiales de diferente flexibilidad y consistencia. Conclusiones: El prototipo rápido le da estado físico a las imágenes virtuales 3D, permitiendo la docencia y entrenamiento del equipo quirúrgico.

Prevalence of Escherichia coli O157:H7 From House Flies (Diptera: Muscidae) and Dairy Samples in North Central Florida1.

PubMed

Burrus, Roxanne G; Hogsette, Jerome A; Kaufman, Phillip E; Maruniak, James E; Simonne, Amy H; Mai, Volker

2017-05-01

La detección de Escherichia coli O157:H7 en las lecherías es importante para mejorar la seguridad de los productos lácteos, y se ha llevado a cabo principalmente mediante el aislamiento de las bacterias a partir de las muestras de estiércol. Sin embargo, los componentes biliares presentes en el estiércol complica la identificación genética utilizando la técnica del PCR, y el aislamiento microbiológico se dificulta por la presencia de bacterias competidoras que comparten características microbiológicas similares. El aislamiento de E. coli O157:H7 a partir de la mosca doméstica evita las dificultades asociadas con el estiércol del ganado. El aislamiento de patógenos a partir de las moscas domésticas proporciona información adicional sobre el potencial impacto epidemiológico de la dispersión de la mosca doméstica en la distribución de patógenos, ya que las moscas domésticas se dispersan desde las lecherías donde la E. coli O157:H7 existe en forma endémica en el ganado. En este estudio, se encontró que las moscas domésticas son 2,6 veces más sensibles para la detección de E. coli O157:H7 en las lecherías. Las moscas son más fáciles de capturar y manejar que el estiércol, y deberían ser utilizadas en cualquier ensayo para detectar E. coli O157:H7 en las lecherías y otros establecimientos. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the US.

Significado de psicólogas/os de atención primaria de salud sobre la intervención psicosocial de grupo en el tratamiento de la depresión en Chile.

PubMed

Andrade, Gonzalo; Espinoza, Adriana

2017-11-01

En Chile, el tratamiento de la depresión en salud pública promueve la realización de Intervenciones Psicosociales en Grupo (IPG) para todos los casos diagnosticados, no obstante, se observa una baja implementación de estas prestaciones. El presente artículo describe y caracteriza, desde el punto de vista de la disciplina psicológica, el significado de psicólogas/os que trabajan en consultorios de atención primaria de salud (APS) sobre las IPG en el tratamiento de la depresión. Se entrevistaron a ocho psicólogas/os de los distintos Servicios de Salud de la Región Metropolitana de Santiago. Este estudio se basó en las premisas de la Teoría Fundamentada, utilizando sus estrategias de análisis. La categoría "los grupos no nos resultan" expone las principales barreras que impiden la realización de estas intervenciones. La carga laboral centrada en atenciones individuales, el escaso presupuesto destinado a su implementación, y la falta de instalaciones adecuadas para realizar las IPG emergen como barreras institucionales. Asi mismo, la "poca fe" en la efectividad del trabajo en grupo, la figura de las/os psicólogas/os como únicas/os profesionales capacitadas/os para trabajar con las emociones, la idea de que la baja adherencia al tratamiento no depende de su ejercicio laboral, y el hecho de que la implementación de las IPG dependa del interés individual de algunas/os profesionales, emergen como las principales resistencias profesionales a su realización. Se discuten los alcances de estas barreras, y se proponen soluciones que favorezcan el cambio cultural necesario para que las/los profesionales e instituciones de salud puedan alinearse en plenitud con el modelo comunitario de salud propuesto por el Plan Nacional de Salud Mental y Psiquiatría (PNSMP).

A novel method for room temperature distribution and conservation of RNA and DNA reference materials for guaranteeing performance of molecular diagnostics in onco-hematology: A GBMHM study.

PubMed

Cayuela, Jean-Michel; Mauté, Carole; Fabre, Anne-Lise; Nibourel, Olivier; Dulucq, Stéphanie; Delabesse, Eric; Villarèse, Patrick; Hayette, Sandrine; Mozziconacci, Marie-Joelle; Macintyre, Elizabeth

2015-10-01

Performance of methods used for molecular diagnostics must be closely controlled by regular analysis of internal quality controls. However, conditioning, shipping and long lasting storage of nucleic acid controls remain problematic. Therefore, we evaluated the minicapsule-based innovative process developed by Imagene (Evry, France) for implementing DNA and RNA controls designed for clonality assessment of lymphoproliferations and BCR-ABL1 mRNA quantification, respectively. DNA samples were extracted from 12 cell lines selected for giving specific amplifications with most BIOMED-2 PCR tubes. RNA samples were extracted from 8 cell line mixtures expressing various BCR-ABL1 transcript levels. DNA and RNA were encapsulated by Imagene and shipped at room temperature to participating laboratories. Biologists were asked to report quality data of recovered nucleic acids as well as PCR results. Encapsulated nucleic acids samples were easily and efficiently recovered from minicapsules. The expected rearrangements at immunoglobulin, T-cell receptor and BCL2 loci were detected in DNA samples by all laboratories. Quality of RNA was consistent between laboratories and met the criteria requested for quantification of BCR-ABL1 transcripts. Expression levels measured by the 5 laboratories were within ±2 fold interval from the corresponding pre-encapsulation reference value. Moreover aging studies of encapsulated RNA simulating up to 100 years storage at room temperature show no bias in quantitative outcome. Therefore, Imagene minicapsules are suitable for storage and distribution at room temperature of genetic material designed for proficiency control of molecular diagnostic methods based on end point or real-time quantitative PCR. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Men's health: non-communicable chronic diseases and social vulnerability.

PubMed

Bidinotto, Daniele Natália Pacharone Bertolini; Simonetti, Janete Pessuto; Bocchi, Silvia Cristina Mangini

2016-08-15

to evaluate the relationship between absences in scheduled appointments and the number of non-communicable chronic diseases and to investigate the relationship between spatial distribution of these diseases and social vulnerability, using geoprocessing. a quantitative study of sequential mixed approach by analyzing 158 medical records of male users to relate the absences and 1250 medical records for geoprocessing. the higher the number of absences in the scheduled medical appointments, the less were the number of non-communicable chronic diseases and the ones listed in the International Classification of Diseases in single men. There were 21 significant geostatistically cases of glucose intolerance in the urban area. Of these, 62% lived in a region with a social vulnerability rating of Very Low, Medium 19%, 14% Low and 5% High. it was observed that the older the men, the greater is the number of chronic diseases and the less they miss scheduled appointments. Regarding the use of geoprocessing, we obtained a significant number of cases of glucose intolerance in urban areas, the majority classified as Very Low social vulnerability. It was possible to relate the spatial distribution of these diseases with the social vulnerability classification; however, it was not possible to perceive a relationship of them with the higher rates of social vulnerability. avaliar a relação entre as faltas em consultas agendadas e o número de doenças crônicas não transmissíveis e averiguar a relação entre distribuição espacial dessas doenças e vulnerabilidade social, utilizando-se o geoprocessamento. estudo quantitativo, de abordagem mista sequencial, sendo analisados 158 prontuários de usuários do sexo masculino para se relacionar as faltas e 1250 prontuários para o geoprocessamento. quanto maior o número de faltas nas consultas médicas agendadas, menores foram a quantidade de doenças crônicas não transmissíveis e as listadas na Classificação Internacional de Doenças em homens solteiros. Obtiveram-se 21 casos geoestatisticamente significantes de intolerância à glicose na zona urbana. Desses, 62% moravam em região com a classificação de vulnerabilidade social Muito Baixa, 19% Média, 14% Baixa e 5% Alta. observou-se que quanto mais velhos os homens, maior é o número de doenças crônicas instaladas e menos eles faltam em consultas agendadas. Quanto ao uso do geoprocessamento, obteve-se número de casos significantes de intolerância à glicose na zona urbana, sendo a maioria classificada como vulnerabilidade social Muito Baixa. Pôde-se relacionar a distribuição espacial dessas doenças com a classificação de vulnerabilidade social, porém, não foi possível perceber uma relação delas com índices mais elevados de vulnerabilidade social. evaluar la relación entre las faltas en las citas programadas y el número de enfermedades crónicas y para investigar la relación entre la distribución espacial de estas enfermedades y la vulnerabilidad social, utilizando geoprocesamiento. estudio cuantitativo de enfoque mixto secuencial y siendo analizadas 158 historias clínicas de los usuarios masculinos para relacionar las faltas y 1250 registros de geoprocesamiento. cuanto mayor eran el número de ausencias en las citas médicas programadas, menores fueron el número, para los hombres solteiros, de enfermedades crónicas y de las incluídas en la Clasificación Internacional de Enfermedades. Se obtuvieron 21 casos de intolerancia a la glucosa geoestadísticamente significativos en el área urbana. De éstos, el 62% viven en una región con calificación de vulnerabilidad social muy baja 19%, media, 14% baja y 5% Alta. se observó que cuanta mayor la edad de los hombres, mayor es el número de enfermedades crónicas instaladas y menos faltas en las citas programadas. Respecto al uso de geoprocesamiento, obtuvimos número significativo de casos de intolerancia a la glucosa en las zonas urbanas, la mayoría clasificada como vulnerabilidad social Muy baja. Se podría relacionarse la distribución espacial de estas enfermedades con la clasificación de la vulnerabilidad social, sin embargo, no fue posible ver una relación de esto con mayores tasas de vulnerabilidad social.

[In Process Citation].

PubMed

Álvarez, Cristian; Ramírez-Campillo, Rodrigo; Vallejos-Rojas, Andrea; Jaramillo-Gallardo, Javiera; Salas Bravo, Carlos; Cano-Montoya, Johnattan; Celis-Morales, Carlos

2016-03-25

 Introducción: obesidad e inactividad física son importantes factores de riesgo para el desarrollo de hipertensión en adultos. No obstante, hay poca evidencia sobre el efecto de estos factores de riesgo en el desarrollo de hipertensión en población infantil. Objetivo: investigar la asociación del estado nutricional, niveles de actividad física y etnicidad con niveles de hipertensión en escolares entre 6 y 13 años de edad. Métodos: un total de 418 escolares de ascendencia étnica europea (n = 311) y mapuche (n = 107) fueron participantes de este estudio transversal. Se midió el peso, talla, índice de masa corporal (IMC) y presión arterial, utilizando protocolos estandarizados. Resultados: no se encontraron diferencias significativas en IMC, estado nutricional y presión arterial entre niños con ascendencia europea y mapuche. No obstante, la prevalencia de prehipertensión (21,3% vs. 11,1%) e hipertensión (28,9% vs. 18,6%) fue significativamente mayor en escolares mapuches en comparación con europeos, respectivamente. Escolares con ascendencia mapuche tienen un mayor riesgo de desarrollar prehipertensión o hipertensión que escolares con ascendencia europea (OR: 1,92 [1,19 a 3,06], p < 0,01). La prevalencia de hipertensión aumenta significativamente en ambos grupos étnicos con el incremento de IMC y bajos niveles de actividad física. Conclusiones: el riesgo de desarrollar prehipertensión o hipertensión es mayor en población infantil ascendiente de mapuches que ascendiente de europeos y este riesgo se ve acentuado con el incremento de obesidad y bajos niveles de actividad física.

[Not Available].

PubMed

Villa-González, Emilio; Rodríguez-López, Carlos; Barranco-Ruiz, Yaira; Cabezas-Arévalo, Luis Fabián; Chillón, Palma

2016-06-30

Objetivo: analizar la concordancia de dos métodos de medición (Google MapsTM vs. Sistema de Información Geográfica) para la determinación de la distancia desde el domicilio familiar hasta el colegio.Métodos: un total de 542 escolares de entre 8-11 años de edad (media = 9,36 ± 0,6) del sur de España participaron en el estudio, facilitando la dirección de su domicilio familiar. La distancia desde el domicilio familiar al colegio se calculó mediante la utilización de dos programas diferentes:Google MapsTM y Sistema de Información Geográfica (GIS) en ruta y en línea recta. La asociación entre ambos métodos fue analizada utilizando la correlación de Spearman y el grado de acuerdo a través del coeficiente de correlación intraclase (ICC), así como el método Bland Altman.Resultados: la correlación entre ambos métodos de medición propuestos fue muy significativa (r = 0,966, p < 0,001; r = 0,984, p < 0,001; y r = 0,954, p < 0,001, respectivamente), y la concordancia fue excelente (ICC = 0,96, p < 0,001; ICC = 0,92, p < 0,001; ICC = 0,97, p < 0,001).Conclusiones: los métodos de medición estudiados podrían ser utilizados en función de las necesidades de la investigación, al presentar ambos una alta concordancia. Sin embargo, se recomienda la utilización del Sistema de Información Geográfica en ruta si se cuenta con medios yfinanciación, por tratarse de un método constatado en fiabilidad y validez.

Tracing the X-Ray Trail

MedlinePlus

... finalizado el examen, el radiólogo, médico entrenado para la lectura de imágenes para diagnóstico, examina las películas. El radiólogo dicta un informe que describe las técnicas utilizadas para adquirir la imagen, el motivo del examen, antecedentes relevantes del ...

Resultados a longo prazo da angioplastia de artérias renais com stent na doença aterosclerótica: revisão sistemática

PubMed Central

Siqueira, Daniel Emilio Dalledone; Guillaumon, Ana Terezinha

2017-01-01

Resumo A doença renovascular aterosclerótica é a principal causa de hipertensão secundária. A história natural da doença demonstra taxas de progressão de 4 a 12% ao ano. Entre os métodos de tratamento existe a angioplastia com stent de artérias renais; porém, poucos estudos clínicos demonstraram seus resultados a longo prazo. Esta revisão sistemática da literatura se propõe a apresentar os resultados a longo prazo (acima de 24 meses) da angioplastia com stent de artérias renais na doença aterosclerótica em relação à função renal e aos níveis pressóricos no controle da hipertensão. Foi realizada uma ampla pesquisa, utilizando os termos apropriados, nas bases de dados LILACS, EMBASE, SCIELO, Cochrane Library e MEDLINE. De um total de 2.170 referências, apenas sete artigos contemplavam todos os critérios de inclusão. Conclui-se que, a longo prazo, há uma estabilização da função renal, redução dos níveis pressóricos e diminuição do número de classes de medicamentos anti-hipertensivos. PMID:29930639

Propriedades físicas de condensações densas no Escorpião

NASA Astrophysics Data System (ADS)

Vilas-Boas, J. W. S.; Barbosa, P. R., Jr.; Hickel, G. R.

2003-08-01

O conhecimento das propriedade físicas das condensações das nuvens escuras e sua relação com a dinâmica das núvens é um dos caminhos para o entendimento dos mecanismos de formação de estrelas de massas pequenas. Nesse trabalho, 8 condensações da nuvem escura do Escorpião foram observadas através de transições das moléculas de 13CO, C18O e NH3, utilizando-se os radiotelescopios de 15 m do SEST e 64 m de PARKES. Embora localizadas na superfície de uma bolha com velocidade de expansão entre 12 km/s e 15 km/s (Vilas-Boas et al), as linhas de monóxido de carbono apresentaram características típicas daquelas observadas em nuvens escuras. Em apenas uma condensação, contendo um objeto Pre-Sequência Principal (PMS), foi detectada emissão da molécula de amônia. A comparação direta entre as propriedades dessas condensações densas (núcleos) e aquelas identificadas na Musca, que se caracteriza por ser uma núvem de baixa atividade de formação estelar, mostra que elas têm propriedades idênticas e que as eficiências de formação estelar nos núcleos de ambas as nuvens são similares.

Frank Middelburg (1936-1985)

NASA Astrophysics Data System (ADS)

Ardeberg, A.

1985-12-01

La noticia de la desaparicion de Frank Middelburg, en el dia 15 de Noviembre de 1985, conmovio a tode el mundo astronomico con un sentimiento especial de tristeza. Frank no solo era un experto reconocido en el campo de procesamiento de imagen y un ingeniero de sistemas altamente respetado, tambien era un preciado amigo y colega.

Observações no infravermelho médio de objetos estelares jovens em NGC 3576

NASA Astrophysics Data System (ADS)

Barbosa, C.; Damineli, A.; Blum, R.; Conti, P.

2003-08-01

Apresentamos os resultados de observações no infravermelho médio de candidatos a objetos estelares jovens e massivos em NGC 3576. As imagens de alta resolução foram obtidas no observatório Gemini Sul com o uso dos filtros em 10,8, 7,9, 9,8, 12,5 e 18,2 mm. Nossas imagens mostram a fonte IRS 1 resolvida em 4 objetos pela primeira vez em 10 mm. Para cada objeto obtivemos a distribuição espectral de energia de 1.2 até 18 mm, bem como a temperatura de cor, a distribuição espacial e a profundidade óptica em 9,8 mm da poeira circunstelar. Apresentamos uma estimativa das massas dos objetos estudados, baseados na luminosidade emitida no infravermelho médio, bem como um modelo para explicar as diferentes características observadas de cada objeto. Finalmente discutimos a possível localização da(s) fonte(s) de ionização de NGC 3576.

Effective Universal Coverage of Diabetes Mellitus Type 2 in Chile.

PubMed

Guerrero-Núñez, Sara; Valenzuela-Suazo, Sandra; Cid-Henríquez, Patricia

2017-04-06

determine the prevalence of Effective Universal Coverage of Diabetes Mellitus Type 2 in Chile and its relation with the variables: Health Care Coverage of Diabetes Mellitus Type 2; Average of diabetics with metabolic control in 2011-2013; Mortality Rate for Diabetes Mellitus; and Percentage of nurses participating in the Cardiovascular Health Program. cross-sectional descriptive study with ecological components that uses documentary sources of the Ministry of Health. It was established that there is correlation between the Universal Effective Coverage of Diabetes Mellitus Type 2 and the independent variables; it was applied the Pearson Coefficient, being significant at the 0.05 level. in Chile Universal Health Care Coverage of Diabetes Mellitus Type 2 (HbA1c<7% estimated population) is less than 20%; this is related with Mortality Rate for Diabetes Mellitus and Percentage of nurses participating in the Cardiovascular Health Program, being significant at the 0.01 level. effective prevalence of Universal Health Coverage of Diabetes Mellitus Type 2 is low, even though some regions stand out in this research and in the metabolic control of patients who participate in health control program; its relation with percentage of nurses participating in the Cardiovascular Health Program represents a challenge and an opportunity for the health system. determinar a prevalência de Cobertura Universal Efetiva da Diabetes Mellitus tipo 2 em Chile e sua relação com as variáveis; Cobertura da Diabetes Mellitus tipo 2, Média de diabéticos com controle metabólico em 2011-2013, Taxa de Mortalidade por Diabetes Mellitus e Percentagem de participação de enfermeiras no Programa de Saúde Cardiovascular. estudo descritivo transversal com componentes ecológicos, utilizando fontes documentais do Ministério da Saúde. Foi estabelecida correlação entre Cobertura Universal Efetiva da Diabetes Mellitus tipo 2 e as variáveis independentes, aplicando o Coeficiente de Pearson, sendo significante ao 0,05. no Chile a Cobertura Universal Efetiva da Diabetes Mellitus tipo 2 (HbA1c<7% em população estimada) é menor que 20%. Esta se relaciona com uma Taxa de Mortalidade por Diabetes Mellitus e Percentagem de participação de enfermeiras no Programa de Saúde Cardiovascular, que ademais é significativa ao 0,01. a prevalência de Cobertura Universal Efetiva da Diabetes Mellitus tipo 2 é baixa, mesmo quando algumas regiões se destacam nas pesquisas e no controle metabólico de pacientes assistentes ao controle. Sua relação com a Percentagem de participação de enfermeiras no Programa de Saúde Cardiovascular se constitui em um desafio e oportunidade em saúde. determinar la prevalencia de la Cobertura Universal Efectiva de la diabetes mellitus tipo 2 en Chile y su relación con las variables: Cobertura de Diabetes Mellitus tipo 2, Promedio de diabéticos con control metabólico en 2011-2013, Tasa de Mortalidad por Diabetes Mellitus y Porcentaje de participación de enfermeros en el Programa de Salud Cardiovascular. estudio descriptivo transversal con componentes ecológicos, utilizando fuentes documentales del Ministerio de Salud. Se estableció que existe correlación entre la Cobertura Universal Efectiva de la Diabetes Mellitus tipo 2 y las variables independientes, aplicando el Coeficiente de Pearson, siendo significativa al nivel 0,05. en Chile la Cobertura Universal Efectiva de Diabetes Mellitus tipo 2 (HbA1c<7% en población estimada) es menor que 20%; esta se relaciona con la Tasa de Mortalidad por Diabetes Mellitus y con el Porcentaje de participación de enfermeras en el Programa de Salud Cardiovascular, que es significativa al nivel 0,01. la prevalencia de Cobertura Universal Efectiva de la Diabetes Mellitus tipo 2 es baja; sin embargo algunas regiones se destacan en la cobertura y en el control metabólico de pacientes que participan del control de salud. La relación de la cobertura con el porcentaje de participación de enfermeras en el Programa de Salud Cardiovascular es un desafío y una oportunidad en salud.

Estudio comparativo de las moléculas isovalentes de interés atmosférico CF3Cl y CF3Br y sus correspondientes halógenos aislados Cl y Br.

NASA Astrophysics Data System (ADS)

Mayor, E.; Velasco, A. M.; Martín, I.; Lavín, C.

Los estados Rydberg moleculares han suscitado en los últimos años un creciente interés entre los espectroscopistas experimentales, motivado en parte por el desarrollo de nuevas técnicas espectroscópicas capaces de investigar estos estados altamente excitados electrónicamente. Los procesos de fotoabsorción que implican estados Rydberg en los derivados halogenados del metano son de gran importancia, debido a su abundancia en la atmósfera y a sus implicaciones medioambientales. Por ello, la obtención de datos relativos a sus fuerzas de oscilador es de gran interés. En este trabajo se aborda el estudio de dichas propiedades para las moléculas isovalentes CF3Cl y CF3Br. Ambas moléculas presentan idéntica estructura electrónica para el estado fundamental por lo que se espera que sus espectros Rydberg presenten grandes similitudes, en ausencia de perturbaciones. Por ello y dada la escasez de datos relativos a fuerzas de oscilador, hemos establecido la corrección de nuestros resultados en base a las analogías esperadas en las intensidades espectrales correspondientes a transiciones análogas. Por otro lado, Novak y col. [1] han encontrado experimentalmente un marcado carácter atómico en el espectro correspondiente a estas moléculas, siendo muy similar a los de los átomos de Cl y Br. Por ello en el presente trabajo, además de establecer la comparación entre ambas moléculas hemos buscado las similitudes con sus respectivos halógenos. Los cálculos relativos a las especies moleculares se han realizado utilizando la Metodología Molécular de Orbítales de Defecto Cuántico (MQDO) [2], mientras que para el estudio de los átomos de Cl y Br se empleó la versión relativista del método (RQDO) [3].

Investigaccion-accion en la sala de clases sobre las creencias de la cultura de la ciencia de un grupo de estudiantes universitarios y su relacion reciproca con el aprendizaje de las ciencias biologicas

NASA Astrophysics Data System (ADS)

Cordova-Santiago, Lizzette Astrid

La investigacion---accion que se llevo a cabo en la sala de clases tenia como punto de partida las creencias de la cultura de la ciencia de un grupo de estudiantes universitarios para luego examinar sus implicaciones en el proceso de aprendizaje de las Ciencias Biologicas. ¿Que se supone que hagan las creencias en relacion con el aprendizaje? ¿En que consiste incorporar este aspecto a la practica educativa universitaria? Utilizando el modelo de Kemmis y McTaggart (1987) la investigacion-accion se planteo como un proceso dinamico en cuatro momentos en espiral constituidos por la planificacion, la accion, la observacion y la reflexion. Cada una de las fases tuvo una intencion retrospectiva y prospectiva formando una espiral de autorreflexion del conocimiento y la accion. Se llevaron a cabo audio grabaciones en clases y analisis de documentos. Ademas, la profesora-investigadora hizo un portafolio para reflexionar sobre las creencias de la cultura de la ciencia que tienen los estudiantes y las creencias del aprendizaje que tiene la profesora y sobre como la comprension de estos elementos ayudo a mejorar su practica educativa a traves del tiempo. Los resultados obtenidos apuntan a que las creencias de la cultura de la ciencia que tiene el grupo de estudiantes son diversas. Ellos si creen que la ciencia tiene una cultura la cual describieron como: complicada y desconocida que evoluciona constantemente, que es un conjunto de metodos, que es altamente tecnologica, que resuelve problemas de salud, ayuda a interpretar la realidad del mundo que los rodea y su origen y que existen unas intersecciones entre la ciencia y el poder. Sobre las creencias del proceso de aprendizaje de la profesora-investigadora, estas senalan que el modelaje de actores, la vision de la academia que tiene ella asi como la participacion y negociacion entre todos los involucrados en el proceso educativo, son factores que inciden en el proceso de aprendizaje.

Ondas de choque em jatos de quasares e objetos BL Lacertae

NASA Astrophysics Data System (ADS)

Melo, F. E.; Botti, L. C. L.

2003-08-01

Este trabalho é parte de um projeto que vem sendo realizado há dois anos no CRAAM, cujos objetivos principais são analisar e aplicar um modelo generalizado de ondas de choque em jatos relativísticos de plasma, presentes em quasares e objetos BL Lacertae, para explicar a variabilidade observada nestes objetos. O método consiste em uma decomposição de curvas de luz em séries de explosões similares, em várias freqüências, baseando-se em uma evolução espectro-temporal média das explosões. A partir da evolução média, um ajuste de cada explosão é feito com base em equações empíricas, modificando-se apenas parâmetros específicos de cada explosão. Inicialmente o modelo foi aplicado ajustando-se as curvas de luz a explosões delineadas por uma evolução do choque em três estágios, segundo a predominância do processo de emissão: síncrotron, Compton e adiabático. Entretanto, nesta nova fase de projeto, visando uma parametrização mais concisa, uma otimização do algoritmo de ajuste e uma convergência mais rápida, a formulação para cada evento foi assumida com uma evolução em apenas dois estágios: subida e descida. Isto possibilitou uma ótima delineação das curvas de luz das fontes OV236, OJ287, 3C273 e BL Lac, entre 1980 e 2000, nas freqüências 4.8, 8.0, 14.5 e 22 GHz, utilizando-se dados do Observatório da Universidade de Michigan, do Observatório do Itapetinga (Atibaia SP) e do Observatório Metsähovi. Como conclusões importantes, verificou-se que: os parâmetros ajustados descrevem o comportamento do jato; os valores do índice que descreve a expansão do jato sugerem que o mesmo se expande de uma forma não-cônica; o campo magnético é turbulento atrás da frente de choque; e as peculiaridades das explosões são devidas à influência de grandezas tais como o coeficiente da distribuição espectral de energia dos elétrons, a intensidade de campo magnético e o fator de feixe Doppler, no início do choque.

Sentido de coherencia y mapa de activos para la salud en jóvenes presos de la Comunidad Valenciana en España.

PubMed

Vera-Remartínez, Enrique J; Paredes-Carbonell, Joan J; Aviñó Juan-Ulpiano, Dory; Jiménez-Pérez, Mercedes; Araujo Pérez, Rosa; Agulló-Cantos, José M; Mora Notario, Almudena

2017-09-01

Estudio realizado desde el enfoque de la salutogénesis que pretende determinar el sentido de coherencia (SOC) en jóvenes presos de la Comunidad Valenciana en España y elaborar un mapa de activos para la salud dirigido a promover la salud en esta población. Se utilizó el test "SOC-13" y un cuestionario de preguntas abiertas elaborado ad hoc, el cual autocompletaron los internos de 18 a 22 años de edad, de los tres centros penitenciarios de la región. Participaron 124 jóvenes varones (ya que no había ninguna mujer) y se recogieron variables sociodemográficas y penitenciarias. En el análisis cuantitativo, las variables categóricas se expresaron como frecuencias absolutas y relativas; y las cuantitativas, mediante medias con intervalos de confianza (IC) al 95%. Se realizó un estudio comparativo bivariante, utilizando las siguientes pruebas: Student t-test, análisis de variación (ANOVA), Wilcoxon y Ji-cuadrado. Del cuestionario de preguntas abiertas, se realizó un análisis cualitativo descriptivo temático de los activos identificados, clasificándolos en: internos (recursos personales, en relación con los demás y capacidad para realizar comportamientos saludables) y externos (personas, grupos, instituciones y espacios físicos, situados tanto dentro como fuera de prisión). La edad media fue de 21,1 años (IC 95%: 20,8-21,3); y el SOC de 52,4 (IC 95%: 50,5-54,3), de entre un valor mínimo de 13 y máximo de 91 para la prueba. Los internos del centro penitenciario que ofrecía más actividades escolares y deportivas obtuvieron una puntuación mayor en la dimensión de significatividad del SOC ( p = 0,024), y los internos inmigrantes presentaron un SOC superior ( p = 0,037) a los españoles, en los tres centros. Los jóvenes identificaron los activos internos que cualitativamente se vinculan con las dimensiones de comprensibilidad, manejabilidad y significatividad del SOC; y los activos externos, sobre todo los amigos, familiares y espacios relacionados con la actividad físico-deportiva, tanto dentro como fuera de prisión. Estos activos y sus interrelaciones podrían incorporarse al diseño de futuras intervenciones de promoción de la salud.

Teaching and Popularization of Astronomy in Latin America by the Liada Perspective. (Spanish Title: Enseñanza y Divulgación de la Astronomía en la América Latina en la Perspectiva de la Liada.) Ensino e Divulgação da Astronomia na América Latina na Perspectiva da Liada

NASA Astrophysics Data System (ADS)

Bretones, Paulo Sergio

2008-12-01

The goal of this work is to present an analysis of the developed activities of the Teaching and Popularization Section (SEDA) of the Liga Ibero-Americana de Astronomía (LIADA). After a history of the LIADA, are presented the projects of the section that have the support of 16 coordinators from most Latin-American countries. The projects that aim to attract the attention of the general public, teachers and students to encourage the observation and send reports to be posted at the Internet page are presented. More specifically, the projects and reports related with eclipses ocurriesd since the year 2000. Using the available files on the page of the section, an analysis and discussion about their importance for scientific education is done. It is presented a data form as a suggestion for reports buy individuais or institutions and the importance of the systematization of experiences to give more visibility and changes of informations in the area. It is concluded with an assessment of the projects, their potential and limitations, as well as suggestions of future projects looking for more interaction between the Latin American countries and making the Section available to this goal.

Esto trabajo visa divulgar y analizar las actividades de La Sección de Enseñanza y Divulgación de la Astronomía (SEDA) de la Liga Iberoamericana de Astronomía (LIADA). Después de un histórico da la LIADA, son presentados los diversos proyectos de la Sección que cuenta con la colaboración de los coordinadores locales en la mayoría de los países de la América Latina. Son presentados los proyectos que visan chamar la atención de público en general, estudiantes y profesores para la observación del cielo e posterior envío de los relatos para colocación en la página de La Sección en la Internet. Más específicamente son analizados los proyectos y relatos relacionados con los eclipses ocurridos desde el año 2000. Utilizando-se los ficheros disponibilizados en la página de la Sección, faz-se una análisis y discusión sobre la importancia de tales relatos para finalidades educacionales. Es presentada una Hoja de reporte elaborado como sugestión para presentación de relatos por parte de individuos y instituciones ben como discutida la importancia de la sistematización de experiencias visando mayor visibilidad y cambio de informaciones en el área. Concluí con una evaluación de los proyectos, su potencial y limitaciones, ben como sugestiones de proyectos futuros visando mayor interacción entre los países de la América Latina y tornando disponible la Sección para esta finalidad.

Esse trabalho visa divulgar e analisar as atividades da Seção de Ensino e Divulgação de Astronomia (SEDA) da Liga Iberoamericana de Astronomia (LIADA). Após um histórico da LIADA, são apresentados os diversos projetos da Seção que conta com a colaboração de coordenadores locais na maioria dos países da América Latina. São apresentados os projetos que visam chamar a atenção do público em geral, estudantes e professores para a observação do céu e posterior envio de relatos para colocação na página da Seção na Internet. Mais especificamente são analisados os projetos e relatos relacionados aos eclipses ocorridos desde o ano 2000. Utilizando-se os arquivos disponibilizados na página da Seção, faz-se uma análise e discussão sobre a importância de tais relatos para finalidades educacionais. É apresentado um formulário elaborado como sugestão para apresentação de relatos por parte de indivíduos e instituições bem como discutida a importância da sistematização de experiências visando maior visibilidade e troca de informações na área. Conclui com uma avaliação dos projetos, seu potencial e limitações, bem como sugestões de projetos futuros visando maior interação entre os países da América Latina e tornando disponível a Seção para esta finalidade.

Dimensions of Manic Symptoms in Youth: Psychosocial Impairment and Cognitive Performance in the IMAGEN Sample

ERIC Educational Resources Information Center

Stringaris, Argyris; Castellanos-Ryan, Natalie; Banaschewski, Tobias; Barker, Gareth J.; Bokde, Arun L.; Bromberg, Uli; Büchel, Christian; Fauth-Bühler, Mira; Flor, Herta; Frouin, Vincent; Gallinat, Juergen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Itterman, Bernd; Lawrence, Claire; Nees, Frauke; Paillere-Martinot, Marie-Laure; Paus, Tomas; Pausova, Zdenka; Rietschel, Marcella; Smolka, Michael N.; Schumann, Gunter; Goodman, Robert; Conrod, Patricia

2014-01-01

Background: It has been reported that mania may be associated with superior cognitive performance. In this study, we test the hypothesis that manic symptoms in youth separate along two correlated dimensions and that a symptom constellation of high energy and cheerfulness is associated with superior cognitive performance. Method: We studied 1755…

Muscle dysmorphia: detection of the use-abuse of anabolic adrogenic steroids in a Spanish sample.

PubMed

González-Martí, Irene; Fernández-Bustos, Juan Gregorio; Contreras Jordán, Onofre Ricardo; Sokolova, Marina

2017-07-14

Debido a una distorsión en la imagen corporal, las personas que padecen Dismorfia Muscular se perciben menos musculosas de lo que son en realidad. Con el fin de aumentar su musculatura, algunas de estas personas hacen uso de hormonas cuya función principal es la del aumento del tamaño muscular. Por lo que el objetivo de este estudio es conocer la prevalencia del uso de hormonas en personas afectadas por Dismorfia Muscular. 562 hombres y 172 mujeres fisicoculturistas y levantadores de pesas, a los que se le administraron diferentes cuestionarios para conocer, primero si padecían el trastorno, y después en qué porcentaje usaban hormonas la muestra afectada. Para la creación de los modelos de regresión de la dismorfia muscular fueron empleadas las técnicas estadísticas de árboles de decisión (R = 0.78 y R2 = 0.62). Los resultados indican que casi un 50% de participantes, afectados por este trastorno, hacen uso de estas drogas. Due to a distortion in the body image, the people who suffer from muscle dysmorphia have the self-perception of being less muscular than they currently are. With the aim of increasing their muscular development, they resort to the use of AAS. The purpose of the present study is to know the prevalence of the use of AAS in a Spanish sample affected by muscle dysmorphia. 562 male and 172 female bodybuilders and weightlifters were provided with different questionnaires in order to know, firstly, if they suffered from this disorder and, secondly, the percentage of the participants affected who use these substances. Decision trees and regression was applied to create explanatory models for muscle dysmorphia (R = 0.78 and R2 = 0.62). The results show that almost 50% of the participants, male and female, affected by this disorder use this kind of drugs.

Mental health in the Family Health Strategy as perceived by health professionals.

PubMed

Souza, Jacqueline de; Almeida, Letícia Yamawaka de; Luis, Margarita Antonia Villar; Nievas, Andreia Fernanda; Veloso, Tatiana Maria Coelho; Barbosa, Sara Pinto; Giacon, Bianca Cristina Ciccone; Assad, Francine Baltazar

2017-01-01

to analyze the management of mental health needs in primary care as perceived by Family Health Strategy professionals. this was a qualitative descriptive exploratory study developed within the coverage area of five family health teams. The data were collected using observation, group interviews, individual semi-structured interviews, and focus groups. Content analysis was conducted using text analysis software and interpretation was based on the corresponding analytical structures. numerous and challenging mental health demands occur in this setting, for which the teams identified care resources; however, they also indicated difficulties, especially related to the operationalization and integration of such resources. there is a need for a care network sensitive to mental health demands that are better coordinated and more effectively managed. analisar o manejo das necessidades de saúde mental na atenção primária à saúde de acordo com a percepção dos profissionais da Estratégia Saúde da Família. estudo qualitativo, descritivo exploratório, desenvolvido no território de abrangência de cinco equipes de saúde da família. Os participantes foram cinco enfermeiras, cinco coordenadores e 17 agentes comunitários de saúde. Os dados foram coletados utilizando observação, entrevistas grupais, entrevistas individuais semiestruturadas e grupos focais. Fez-se a análise de conteúdo com o auxílio de um Software de análise textual, e a interpretação baseou-se nas estruturas analíticas correspondentes. inúmeras e desafiadoras demandas de saúde mental têm sido acolhidas nesse setting, para as quais as equipes identificaram recursos de atendimento; no entanto, apontaram dificuldades, sobretudo relacionadas à operacionalização e integração destes recursos. destaca-se a necessidade de uma rede de cuidados sensível a tais demandas, mais articulada e gerida de modo eficaz.

Comunicación de pareja y VIH en mujeres en desventaja social

PubMed Central

Rosina Cianelli, A.; Lilian Ferrer, L.; Margarita Bernales, S.; Natalia Villegas, R.

2009-01-01

Introducción La epidemia de VIH y SIDA se ha diseminado rápidamente a nivel mundial tendiendo a la feminización, pauperización y heterosexualización. La comunicación de pareja en torno el VIH es descrita como uno de los factores protectores en la adquisición de esta enfermedad, favoreciendo la adopción de conductas sexuales seguras tales como la negociación de pareja y la utilización de preservativo, consideróndose como un pilar fundamental en la incorporación de medidas de autocuidado en la sexualidad femenina. Objetivo Determinar el nivel de comunicación de pareja en torno al VIH en mujeres chilenas en desventaja social. Metodología Cuatrocientas noventa y seis mujeres contestaron la entrevista inicial de la investigación “Testing an HIV/AIDS Prevention Intervention for Chilean Women” (RO1 TW 006977 PI Cianelli). Se utilizó la escala “Health protective sexual communication scale (HPC)” (0–10 puntos). Se realizó un análisis descriptivo utilizando el programa SPSS 16.0. Resultados El promedio del nivel de comunicación de pareja fue de 3,26 ± 2,7 puntos con la pareja principal, de 2,52 ± 2,48 puntos con una segunda pareja y de 0 puntos con una tercera pareja. Los temas de menor comunicación entre las parejas fueron el uso de preservativo y la realización del test para VIH antes de tener relaciones sexuales. Conclusión Las mujeres de la muestra presentan bajos niveles de comunicación de pareja en relación a VIH con todas sus parejas sexuales. Son necesarias estrategias que potencien este tópico dentro de las intervenciones de prevención de VIH y SIDA de manera de fortalecer la adopción de conductas de autocuidado en torno al tema. PMID:19936328

Astronomía Gamma desde El Leoncito

NASA Astrophysics Data System (ADS)

Rovero, A. C.; Colombo, E.; Sahade, J.; Weekes, T. C.

La astronomía gamma, en el extremo de energías detectadas hasta el presente, se encuentra en desarrollo en muchas partes del mundo y proporciona resultados sorprendentes a medida que la tecnología avanza en el desarrollo de nuevos detectores. La técnica Cherenkov Atmosférica es la utilizada para la detección, mediante telescopios en tierra, del efecto secundario causado por la radiación gamma de muy altas energías (E ≈ TeV). Por medio de telescopios o arreglos de detectores y utilizando la técnica mencionada, se han podido detectar algunas fuentes puntuales de mucha importancia astrofísica como la Nebulosa del Cangrejo y la galaxia de núcleo activo Markarian 421. El sistema instalado en San Juan, en cooperación con el grupo de Radiación Gamma del Observatorio Whipple, está constituído por tres colectores de 1.5m que registran pulsos de luz generados por las cascadas de partículas producidas por rayos cósmicos de todo tipo al entrar en la atmósfera terrestre. El sistema opera por barrido en ascención recta de la fuente observada que, para esta etapa del experimento, es el Centro Galáctico. Esta fuente extensa es conocida como emisor gamma de energías inferiores al TeV y ha sido observada anteriormente en este rango de energía desde el hemisferio norte pero con elevaciones bajas, situación no óptima para este tipo de técnica. Se presentan los primeros resultados del análisis de los datos obtenidos observando la región del Centro Galáctico, luego de dos años de observaciones, así como una descripción de la técnica Cherenkov Atmosférica y del equipo utilizado en la experiencia.

CONVENTIONAL VIDEOENDOSCOPY CAN IDENTIFY HELICOBACTER PYLORI GASTRITIS?

PubMed

Gomes, Alexandre; Skare, Thelma Larocca; Prestes, Manoel Alberto; Costa, Maiza da Silva; Petisco, Roberta Dombroski; Ramos, Gabriela Piovezani

2016-01-01

Studies with latest technologies such as endoscopy with magnification and chromoendoscopy showed that various endoscopic aspects are clearly related to infection by Helicobacter pylori (HP). The description of different patterns of erythema in gastric body under magnification of images revived interest in identifying these patterns by standard endoscopy. To validate the morphologic features of gastric mucosa related to H. pylori infection gastritis allowing predictability of their diagnosis as well as proper targeting biopsies. Prospective study of 339 consecutive patients with the standard videoendoscope image analysis were obtained, recorded and stored in a program database. These images were studied with respect to the presence or absence of H. pylori, diagnosed by rapid urease test and/or by histological analysis. Were studied: a) normal mucosa appearance; b) mucosal nodularity; c) diffuse nonspecific erythema or redness (with or without edema of folds and exudate) of antrum and body; d) mosaic pattern with focal area of hyperemia; e) erythema in streaks or bands (red streak); f) elevated (raised) erosion; g) flat erosions; h) fundic gland polyps. The main exclusion criteria were the use of drugs, HP pre-treatment and other entities that could affect results. Applying the exclusion criteria, were included 170 of the 339 patients, of which 52 (30.58%) were positive for HP and 118 negative. On the positive findings, the most associated with infection were: nodularity in the antrum (26.92%); presence of raised erosion (15.38%) and mosaic mucosa in the body (21.15%). On the negative group the normal appearance of the mucosa was 66.94%; erythema in streaks or bands in 9.32%; flat erosions 11.86%; and fundic gland polyps 11.86%. Endoscopic findings are useful in the predictability of the result and in directing biopsies. The most representative form of HP related gastritis was the nodularity of the antral mucosa. The raised erosion and mucosa in mosaic in the body are suggestive but not specific to the infection. The other forms were not conclusive of the presence of HP. Estudos com tecnologias mais recentes como endoscopia com magnificação e cromoscopia mostraram que vários aspectos endoscópicos estão claramente associados à infecção por Helicobacter pylori. A descrição de padrões diferenciados de enantema no corpo gástrico através da magnificação de imagens reavivou o interesse na identificação desses padrões pela endoscopia convencional. Validar os padrões morfológicos de mucosa gástrica usando videogastroendoscopia convencional relacionados à gastrite por infecção por Helicobacter pylori, permitindo previsibilidade do seu diagnóstico e o direcionamento de biópsias. Estudo prospectivo de 339 pacientes consecutivos com análise das imagens de videogastroendoscopia obtidas, gravadas e armazenadas em banco de dados. Estas imagens foram estudadas com relação à presença ou não do Helicobacter pylori diagnosticado por teste rápido de urease e/ou por pesquisa direta por estudo anatomopatológico. Foram estudados: a) aspecto normal da mucosa; b) nodularidade da mucosa; c) enantema inespecífico difuso de antro e corpo; d) enantema em mosaico ou salpicado; e) enantema em estrias ou faixas; f) erosões elevadas; g) erosões planas; h) pólipos de glândulas fúndicas. Os principais critérios de exclusão foram o uso de medicamentos, tratamento prévio de HP e outras entidades que pudessem interferir nos resultados. Aplicando os critérios de exclusão, incluíram-se 170 dos 339 pacientes sendo 52 (30,58%) positivos para Helicobacter pylori e 118 negativos. No grupo positivo os achados que mais se associaram com a infecção foram: nodularidade no antro (26,92%); presença de erosões elevadas (15,38%) e mucosa em mosaico no corpo (21,15%). No grupo negativo o aspecto normal da mucosa foi de 66,94%; enantema em estrias ou faixas em 9,32%; erosões planas em 11,86%; e pólipos de glândulas fúndicas 11,86%. Achados endoscópicos são úteis na previsibilidade de localização e direcionamento de biópsias na pesquisa do HP. A mais representativa forma de gastrite por HP foi o achado de nodularidade na mucosa antral. As erosões elevadas e mucosa em mosaico no corpo são sugestivas, mas não específicas da infecção. As demais formas não foram conclusivas da presença do HP.

Etnografía acelerada para transformar normas sociales sobre género y sexualidad en hombres puertorriqueños heterosexuales1,2

PubMed Central

Ortiz-Torres, Blanca; Rivera-Ortiz, Rafael J.; Mendoza, Sigrid

2014-01-01

Resumen La construcción de roles de género dominantes contribuyen al riesgo de contraer VIH, y por tal razón se ha urgido a que se integren las normas sociales relativas al género en las intervenciones preventivas del VIH. Este estudio pretende adaptar y desarrollar una intervención que facilite la transformación de normas sociales del género y de prácticas sexuales en hombres puertorriqueños. La intervención propone transformar normas sociales relacionadas al género y sexualidad en barras comunitarias utilizando el modelo de líderes de opinión. Luego de ser elegidos/as, los/as líderes de opinión diseminan mensajes integrando la importancia de relaciones equitativas entre parejas para la prevención del VIH. La primera fase de esta intervención es discutida en este artículo, la cual incluye un proceso de etnografía acelerada para identificar los escenarios comunitarios en los que podemos desarrollar esta intervención y permitirnos entender la cultura de las barras comunitarias. A partir de las observaciones etnográficas, pudimos: desarrollar un protocolo de seguridad para realizar las observaciones, desarrollar un perfil de la cultura de las barras, elegir las barras a participar en las dos condiciones del estudio y adaptar los instrumentos de la intervención para que respondieran a la particularidad de los/as participantes. PMID:25530828

ROBOTIC ASSISTED SINGLE SITE FOR BILATERAL INGUINAL HERNIA REPAIR.

PubMed

Bosi, Henrique Rasia; Guimarães, José Ricardo; Cavazzola, Leandro Totti

2016-01-01

The inguinal hernia is one of the most frequent surgical diseases, being frequent procedure and surgeon´s everyday practice. To present technical details in making hernioplasty using robotic equipment on bilateral inguinal hernia repair with single port and preliminary results with the method. The bilateral inguinal hernia repair was performed by using the Single-Site(c) Da Vinci Surgical Access Platform to the abdominal cavity and the placement of clamps. This technique proved to be effective for inguinal hernia and have more aesthetic result when compared to other techniques. Inguinal hernia repair robot-assisted with single-trocar is feasible and effective. However, still has higher costs needing surgical team special training. A hérnia inguinal é uma das doenças cirúrgicas mais frequentes, tornando-a procedimento frequente e do cotidiano do cirurgião. Apresentar detalhes da técnica da hernioplastia inguinal bilateral robótica por single-site e resultados preliminares com o método. Foi realizada hernioplastia inguinal bilateral assistida por robô, utilizando-se da Vinci Single-Site(c) Surgical Platform para acesso a cavidade abdominal e colocação das pinças. Esta técnica demonstrou-se efetiva para correção da hérnia inguinal, além de apresentar melhor resultado estético quando comparado às outras técnicas. A hernioplastia inguinal assistida por robô com trocarte único é viável e eficaz. Contudo, ainda apresenta custos mais elevados e necessidade de treinamento especial por parte da equipe cirúrgica.

Altered reward processing in adolescents with prenatal exposure to maternal cigarette smoking.

PubMed

Müller, Kathrin U; Mennigen, Eva; Ripke, Stephan; Banaschewski, Tobias; Barker, Gareth J; Büchel, Christian; Conrod, Patricia; Fauth-Bühler, Mira; Flor, Herta; Garavan, Hugh; Heinz, Andreas; Lawrence, Claire; Loth, Eva; Mann, Karl; Martinot, Jean-Luc; Pausova, Zdenka; Rietschel, Marcella; Ströhle, Andreas; Struve, Maren; Walaszek, Bernadeta; Schumann, Gunter; Paus, Tomáš; Smolka, Michael N

2013-08-01

Higher rates of substance use and dependence have been observed in the offspring of mothers who smoked during pregnancy. Animal studies indicate that prenatal exposure to nicotine alters the development of brain areas related to reward processing, which might be a risk factor for substance use and addiction later in life. However, no study has examined the effect of maternal smoking on the offspring's brain response during reward processing. To determine whether adolescents with prenatal exposure to maternal cigarette smoking differ from their nonexposed peers in the response of the ventral striatum to the anticipation or the receipt of a reward. An observational case-control study. Data were obtained from the IMAGEN Study, a European multicenter study of impulsivity, reinforcement sensitivity, and emotional reactivity in adolescents. The IMAGEN sample consists of 2078 healthy adolescents (age range, 13-15 years) recruited from March 1, 2008, through December 31, 2011, in local schools. We assessed an IMAGEN subsample of 177 adolescents with prenatal exposure to maternal cigarette smoking and 177 nonexposed peers (age range, 13-15 years) matched by sex, maternal educational level, and imaging site. Response to reward in the ventral striatum measured with functional magnetic resonance imaging. In prenatally exposed adolescents, we observed a weaker response in the ventral striatum during reward anticipation (left side, F = 14.98 [P < .001]; right side, F = 15.95 [P < .001]) compared with their nonexposed peers. No differences were found regarding the responsivity of the ventral striatum to the receipt of a reward (left side, F = 0.21 [P = .65]; right side, F = 0.47 [P = .49]). The weaker responsivity of the ventral striatum to reward anticipation in prenatally exposed adolescents may represent a risk factor for substance use and development of addiction later in life. This result highlights the need for education and preventive measures to reduce smoking during pregnancy. Future analyses should assess whether prenatally exposed adolescents develop an increased risk for substance use and addiction and which role the reported neuronal differences during reward anticipation plays in this development.

Trastornos mentales y consumo de drogas en la población víctima del conflicto armado en tres ciudades de Colombia.

PubMed

Castaño, Guillermo; Sierra, Gloria; Sánchez, Daniela; Torres, Yolanda; Salas, Carolina; Buitrago, Carolina

2018-05-01

Introducción. La violencia en sus diferentes modalidades incrementa el riesgo de trastornos mentales y de consumo de drogas.Objetivos. Estimar la prevalencia de los trastornos mentales, del uso y abuso de drogas, así como los factores asociados en víctimas de desplazamiento forzado en tres ciudades colombianas.Materiales y métodos. Se hizo un estudio de prevalencia en una muestra de 1.026 personas entre los 13 y los 65 años de edad, a quienes se entrevistó utilizando el instrumento Composite International Diagnostic Interview y el Alcohol Use Disorders Identification Test de la Organización Mundial de la Salud, así como un cuestionario sobre el consumo de drogas modificado a partir de la encuesta del Sistema Interamericano de Datos Uniformes sobre Drogas de la Comisión Interamericana para el Control del Abuso de Drogas de la Organización de Estados Americanos, y otro sobre aspectos relacionados con el desplazamiento forzado. El análisis se hizo mediante el programa estadístico SPSS™, versión 21.Resultados. La prevalencia de vida de los trastornos mentales fue la siguiente: fobia específica, 17,7 %; depresión mayor, 16,4 %; estrés postraumático, 9,9 %; trastorno oposicionista desafiante, 8,9 %; ansiedad por separación, 7,2 %; trastornos de conducta, 5,8 %, y déficit de atención, 5,6 %. La prevalencia de vida del consumo de alcohol fue de 68,7 %; de tabaco, 31,3 %, de marihuana, 11,2 %, de cocaína, 3,5 %, de basuco, 2,0 %, de inhalables, 2,3 %, y de medicamentos ansiolíticos sin receta, 2,5 %, en tanto que 0,7 % de los entrevistados se había inyectado drogas. El presentar cualquiera de los trastornos mentales se asoció con el sexo femenino (odds ratio, OR=1,61; IC95% 1,21-2,14), así como el haber sido sometido a más de un desplazamiento forzado (OR=1,47; IC95 1,05-2,05). El consumo de cualquiera de las drogas se asoció con ser hombre (OR=5,38; IC95% 2,35-12,34).Conclusiones. La alta prevalencia de trastornos mentales y de consumo de drogas en la población estudiada, comparada con la población general, constituye un problema de salud pública que justifica el diseño de planes y la implementación de programas orientados a la recuperación de su bienestar y salud mental.

Epinephrine in cardiac arrest: systematic review and meta-analysis.

PubMed

Morales-Cané, Ignacio; Valverde-León, María Del Rocío; Rodríguez-Borrego, María Aurora

2016-12-08

evaluate the effectiveness of epinephrine used during cardiac arrest and its effect on the survival rates and neurological condition. systematic review of scientific literature with meta-analysis, using a random effects model. The following databases were used to research clinical trials and observational studies: Medline, Embase and Cochrane, from 2005 to 2015. when the Return of Spontaneous Circulation (ROSC) with administration of epinephrine was compared with ROSC without administration, increased rates were found with administration (OR 2.02. 95% CI 1.49 to 2.75; I2 = 95%). Meta-analysis showed an increase in survival to discharge or 30 days after administration of epinephrine (OR 1.23; 95% IC 1.05-1.44; I2=83%). Stratification by shockable and non-shockable rhythms showed an increase in survival for non-shockable rhythm (OR 1.52; 95% IC 1.29-1.78; I2=42%). When compared with delayed administration, the administration of epinephrine within 10 minutes showed an increased survival rate (OR 2.03; 95% IC 1.77-2.32; I2=0%). administration of epinephrine appears to increase the rate of ROSC, but when compared with other therapies, no positive effect was found on survival rates of patients with favorable neurological status. avaliar a efetividade da adrenalina na parada cardíaca e seu efeito na sobrevivência e no estado neurológico. revisão sistemática da literatura científica com meta-análise utilizando um modelo de efeitos aleatórios. Revisão em Medline, Embase e Cochrane, desde 2005 até 2015 de ensaios clínicos e estudos observacionais. observou-se aumento nas taxas de retorno de circulação espontânea com a administração de adrenalina (OR 2,02; 95% IC 1,49-2,75; I2=95%) comparadas com a não administração de adrenalina. A meta-análise mostrou um aumento da sobrevivência na alta ou depois de 30 dias da administração de adrenalina (OR 1,23; 95% IC 1,05-1,44; I2=83%). Quando estratificados por ritmos desfibrilháveis e não desfibrilháveis apareceu um aumento da sobrevivência nos ritmos não desfibrilháveis (OR 1,52; 95% IC 1,29-1,78; I2=42%). Também observou-se um incremento de sobrevivência na alta ou depois de 30 dias, quando administrada a adrenalina antes de 10 minutos, isto comparado com administração tardia (OR 2,03; 95% IC 1,77-2,32; I2=0%). a administração de adrenalina parece incrementar a taxa de retorno da circulação espontânea, mas não se tem encontrado um efeito positivo nas taxas de sobrevivência nem nas taxas de pacientes com estado neurológico favorável, em comparação com outras terapias. evaluar la efectividad de la adrenalina en el paro cardíaco y su efecto en la supervivencia y en el estado neurológico. revisión sistemática de la literatura científica con metaanálisis utilizando un modelo de efectos aleatorios. Revisión en Medline, Embase y Cochrane, desde 2005 hasta 2015, de ensayos clínicos y estudios observacionales. se observó aumento en las tasas de retorno de circulación espontánea cuando administrada adrenalina (OR 2,02; 95% IC 1,49-2,75; I2=95%) comparada con la no administración de adrenalina. El metaanálisis mostró un aumento de la supervivencia al alta hospitalaria o a los 30 días cuando administrada adrenalina (OR 1,23; 95% IC 1,05-1,44; I2=83%). La estratificación por ritmos desfibrilables y no desfibrilables mostró un aumento de la supervivencia en ritmos no desfibrilables (OR 1,52; 95% IC 1,29-1,78; I2=42%). También, se observó un incremento en la supervivencia al alta hospitalaria o a los 30 días en la administración de adrenalina antes de 10 minutos comparada con la administración tardía (OR 2,03; 95% IC 1,77-2,32; I2=0%). la administración de adrenalina parece incrementar la tasa de retorno de circulación espontánea, pero no se ha encontrado un efecto positivo en tasas de supervivencia ni en tasas de pacientes con estado neurológico favorable, en comparación con otras terapias.

Nursing knowledge and practices regarding subcutaneous fluid administration.

PubMed

Gomes, Nathália Silva; Silva, Andrea Mara Bernardes da; Zago, Luana Barbosa; Silva, Érica Carneiro de Lima E; Barichello, Elizabeth

2017-01-01

To describe the evidence in the literature regarding the knowledge and practices of the nursing team about subcutaneous administration of drugs and fluids in adults. Integrative review of the literature using the descriptors "nursing", "hypodermoclysis", "drug administration routes", "adult health," and "knowledge," in English, Spanish, and Portuguese, with no publication deadline. Of the 569 articles found, eight made up the sample. A predominance of international journals (75%) with more than five years of publication (62.5%). The analysis of the methodological characteristics showed a predominance of literature reviews (25%), quantitative studies (62.5%), cross-sectional studies (50%), and non-experimental studies (50%). Although it is an old technique with proven efficacy, hypodermoclysis is still little used, a puzzling fact due to its advantages and indications for any age. descrever as evidências, na literatura, sobre os conhecimentos e as práticas da equipe de enfermagem na administração de medicamentos e de fluidos por via subcutânea no adulto. revisão integrativa da literatura utilizando os descritores enfermagem, hipodermóclise, vias de administração de medicamentos, saúde do adulto e conhecimento; nos idiomas inglês, espanhol e português, sem data limite de publicação. Dos 569 artigos encontrados, oito compuseram a amostra. predomínio de revistas internacionais (75%) e com mais de cinco anos de publicação (62,5%). Ao analisarem-se as características metodológicas, predominaram: revisões de literatura (25%), estudos quantitativos (62,5%), estudos transversais (50%) e não-experimentais (50%). apesar de se tratar de uma técnica antiga com eficácia comprovada, a hipodermóclise ainda é pouco utilizada, fato incoerente pelas suas vantagens e suas indicações para qualquer idade.

Densidad de desarrollo alta y baja en Puerto Rico

Treesearch

William A. Gould; Sebastian Martinuzzi; Olga M. Ramos Gonzalez

2008-01-01

Este mapa demuestra la distribución de terrenos de alta y baja densidad de desarrollo urbano en Puerto Rico (Martinuzzi et al. 2007). El mapa fue creado mediante el analisis de un mosaico de imagenes de satelite Landsat ETM+ de los años 2000 – 2003. La clasificacion no supervisada ISODATA (“Iterative Self-Organizing Data Analysis Technique”) (ERDAS 2003) fue utilizada...

Influência da termoablação com baixa e alta densidade de energia na junção safeno-femoral, utilizando laser endovenoso 1470 nm

PubMed Central

de Araujo, Walter Junior Boim; Erzinger, Fabiano Luiz; Caron, Filipe Carlos; Nejm, Carlos Seme; Timi, Jorge Rufino Ribas

2017-01-01

Resumo Contexto Faz-se importante o conhecimento técnico dos ajustes de potência e de densidade de energia linear endovenosa (linear endovenous energy density, LEED) adequados para atingir o objetivo final da termoablação endovenosa (endovenous laser ablation, EVLA). Objetivos Avaliar a influência de diferentes LEEDs em termos de patência e presença de refluxo, bem como determinar a evolução clínica. Métodos Foram incluídas 60 veias safenas magnas (VSM). Os pacientes foram randomizados em dois grupos: EVLA com baixa potência (7 W e LEED de 20-40 J/cm) e com alta potência (15 W e LEED de 80-100 J/cm). O acompanhamento com eco-Doppler e escore de severidade clínica venoso (VCSS) foi realizado nos intervalos de 3-5 dias, 30 dias, 180 dias e 1 ano após o procedimento. Resultados Dezoito pacientes (29 membros) tratados com 7W de potência e 13 pacientes (23 membros) com 15 W completaram o estudo. Não houve diferença significativa considerando idade, tempo de cirurgia e o uso de analgésicos, lateralidade, gênero e presença de comorbidades. O LEED médio foi de 33,54 J/cm no grupo de 7 W e de 88,66 J/cm no de 15 W. Ambos apresentaram melhora no VCSS, redução significativa dos diâmetros da JSF e ausência de diferença significativa quanto ao aumento do comprimento do coto da VSM e de refluxo após o tratamento. Conclusões A utilização de maior densidade de energia mostrou-se mais efetiva em relação à estabilização do comprimento do coto da VSM e do refluxo em 6 meses. Fazem-se necessários estudos com um período de acompanhamento maior para fundamentar essa hipótese. PMID:29930650

Papillary Muscle Free Strain in Patients with Severe Degenerative and Functional Mitral Regurgitation.

PubMed

Kılıcgedik, Alev; Kahveci, Gokhan; Gurbuz, Ahmet Seyfeddin; Karabay, Can Yucel; Guler, Ahmet; Efe, Suleyman Cagan; Aung, Soe Moe; Arslantas, Ugur; Demir, Serdar; Izgi, Ibrahim Akin; Kirma, Cevat

2017-04-01

The role of papillary muscle function in severe mitral regurgitation with preserved and reduced left ventricular ejection fraction and the method of choice to evaluate PM have still been the subjects of controversy. To evaluate and compare papillary muscle function in and between patients with severe degenerative and functional mitral regurgitation by using the free strain method. 64 patients with severe mitral regurgitation - 39 patients with degenerative mitral regurgitation (DMR group) and 25 patients with severe functional mitral regurgitation (FMR group) - and 30 control subjects (control group) were included in the study. Papillary muscle function was evaluated through the free strain method from apical four chamber images of the anterolateral papillary muscle (APM) and from apical three chamber images of the posteromedial papillary muscle (PPM). Global left ventricular longitudinal and circumferential strains were evaluated by applying 2D speckle tracking imaging. Global left ventricular longitudinal strain (DMR group, -17 [-14.2/-20]; FMR group, -9 [-7/-10.7]; control group, -20 [-18/-21] p < 0.001), global left ventricular circumferential strain (DMR group, -20 [-14.5/-22.7]; FMR group, -10 [-7/-12]; control group, -23 [-21/-27.5] p < 0.001) and papillary musle strains (PPMS; DMR group, -30.5 [-24/-46.7]; FMR group, -18 [-12/-30]; control group; -43 [-34.5/-39.5] p < 0.001; APMS; DMR group, (-35 [-23.5/-43]; FMR group, -20 [-13.5/-26]; control group, -40 [-32.5/-48] p < 0.001) were significantly different among all groups. APMS and PPMS were highly correlated with LVEF (p < 0.001, p < 0.001; respectively), GLS (p < 0.001, p < 0.001; respectively) and GCS (p < 0.001, p < 0.00; respectively) of LV among all groups. No correlation was found between papillary muscle strains and effective orifice area (EOA) in both groups of severe mitral regurgitation. Measuring papillary muscle longitudinal strain by the free strain method is practical and applicable. Papillary muscle dysfunction plays a small role in severe MR due to degenerative or functional causes and papillary muscle functions in general seems to follow left ventricular function. PPM is the most affected PM in severe mitral regurgitation in both groups of DMR and FMR. O papel da função do músculo papilar na regurgitação mitral grave com fração de ejeção do ventrículo esquerdo preservada e reduzida e o método de escolha para avaliar PM ainda são objetos de controvérsia. Avaliar e comparar a função dos músculos papilares entre pacientes com insuficiência mitral funcional e degenerativa pelo método free strain. 64 pacientes com insuficiência mitral grave - 39 pacientes com insuficiência mitral degenerativa grave (grupo IMD) e 25 com insuficiência mitral funcional grave (grupo IMF) - e 30 indivíduos controle (grupo controle) foram incluídos no estudo. A função dos músculos papilares foi avaliada pelo método free strain a partir de imagens apicais quatro-câmaras do músculo papilar anterolateral (MPA) e imagens apicais três-câmaras do músculo papilar posteromedial (MPP). Strains circunferenciais e longitudinais globais do ventrículo esquerdo foram avaliados por meio de imagens bidimensionais a partir do rastreamento de conjunto de pontos de cinza (speckle tracking). O strain longitudinal global do ventrículo esquerdo (grupo IMD, -17 [-14,2/-20]; grupo IMF, -9 [-7/-10,7]; grupo controle, -20 [-18/-21] p < 0,001); strain circunferencial global do ventrículo esquerdo (grupo IMD, -20 [-14,5/-22,7]; grupo IMF, -10 [-7/-12]; grupo controle, -23 [-21/-27,5] p < 0,001) e strains de músculos papilares (MPP; grupo IMD, -30,5 [-24/-46,7]; grupo IMF, -18 [-12/-30]; grupo controle; -43 [-34,5/-39,5] p < 0,001; MPA; grupo IMD, (-35 [-23,5/-43]; grupo IMF, -20 [-13,5/-26]; grupo controle, -40 [-32,5/-48] p < 0,001) mostraram-se significativamente diferentes nos grupos. MPA e MPP mostraram-se altamente correlacionados com a FEVE (p < 0,001, p < 0,00; respectivamente), SLG (p < 0,001, p < 0,001; respectivamente) e SCG (p < 0,001, p < 0,001; respectivamente) do VE entre todos os grupos. Não foi encontrada correlação entre os strains de músculos papilares e área eficaz do orifício (AEO) nos grupos de insuficiência mitral grave. A medição do strain longitudinal de músculos papilares pelo método free strain é prática e aplicável. A disfunção dos músculos papilares tem um papel pequeno em IM grave devido a causas degenerativas e funcionais, e a função dos músculos papilares, em general, parece seguir a função ventricular esquerda. O MPP é o MP mais afetado na insuficiência mitral em ambos os grupos, IMD e IMF.

Synthesis of Pure Ca(OH)2 Nanoparticles and Superhydrophobic Suspensions: Consolidation and Waterproofing of Architectural Heritage Materials

NASA Astrophysics Data System (ADS)

Madrid Mendoza, Juan Antonio

El objetivo de esta tesis es investigar sobre la sintesis, propiedades y aplicaciones de las nanoparticulas de Ca(OH)2 para consolidar materiales patrimoniales arquitectonicos. Las nanoparticulas de Ca(OH)2 se han utilizado recientemente en la conservacion del patrimonio, aunque algunos aspectos de la sintesis no son completamente comprendidos. En el presente estudio, hemos desarrollado metodos optimizados para obtener nanoparticulas de alta pureza mediante sintesis de fase homogenea y heterogenea utilizando diferentes materiales de partida. Se han realizado del orden de cien sintesis en diferentes condiciones para comprobar la validez y fiabilidad del metodo sintetico. Los resultados confirman que la temperatura de reaccion tiene una gran influencia en el tamano y la morfologia de las nanoparticulas de Ca(OH)2. Ademas, se ha investigado la estabilidad de las nanoparticulas a lo largo del tiempo en mezclas de 2-propanol / agua, en las que se encontro que la ausencia de agua era critica para evitar la aglomeracion de Ca(OH)2. Una vez dispersas en 2-propanol, las nanoparticulas se han utilizado para consolidar sustratos reales (piedra, adobe y estuco) confirmando su alto rendimiento en terminos de consolidacion superficial y - cuando se mezcla con ciertos surfactantes - en reduccion de la absorcion de agua. Asimismo, se ha investigado el uso de nanoparticulas modificadas basadas en M(OH)2, donde M=Ca2+, Mg2+, con el objetivo de mejorar tanto la cohesion superficial como la durabilidad de los materiales patrimoniales (p. ej. piedra Tabaire). Finalmente, el tratamiento de consolidacion basado en nanoparticulas puras de Ca(OH)2 se utilizo en emplazamientos con valor patrimonial, como edificios historicos y yacimientos arqueologicos (Teatro Romano de Cartagena) obteniendo resultados satisfactorios. The aim of this thesis is to investigate on the synthesis, properties and applications of Ca(OH)2 nanoparticles to consolidate architectural heritage materials. Ca(OH)2 nanoparticles have recently been used in heritage conservation, although some aspects of the synthesis are not fully-understood. In the present study, we have developed optimised methods for obtaining high-purity nanoparticles based on homogenous and heterogeneous phase synthesis using different starting materials. Around one hundred syntheses have been performed to test the validity and reliability of the synthetic method in different conditions. The results confirm that the reaction temperature has a great influence on the size and morphology of Ca(OH)2 nanoparticles. Besides, the nanoparticles stability has been investigated over time in 2-propanol / water mixtures, in which the absence of water was found to be critical to avoid Ca(OH)2 agglomeration. Once dispersed in 2-propanol, the nanoparticles have been used to consolidate real substrates (stone, adobe and stucco) confirming their high performance in terms of surface consolidation and - when mixed with certain surfactants - water absorption. Likewise, the use of modified nanoparticles based on M(OH)2, where M=Ca2+, Mg2+, has been investigated with the aim of improving both the surface cohesion and durability of heritage materials (e.g. Tabaire stone). Finally, the consolidation treatment consisting in pure Ca(OH)2 nanoparticles has been used in cultural heritage sites, such as historical buildings and archaeological monuments (Roman Theatre of Cartagena) leading to satisfactory results.

Self-Image Development: A Chicano Enfasis. Self-Programmed Counseling and Self-Programmed Control. Instructor's Guide = Desarrollo de la Imagen Propia: Enfasis en el Chicano. Sistema de Consejo y Control Auto-Programado. Manuel del Profesor.

ERIC Educational Resources Information Center

Mireles, S. Raymond

Self-Programmed Counseling, the instructor's guidance, and Self-Programmed Control (SPC), the student's response, was initially developed by Title III Project USTED (United Students and Teachers for Educational Development) for Mexican American students on academic probation to use on a non-credit, special group counseling basis. As part of a…

Análise da medição do raio solar em ultravioleta

NASA Astrophysics Data System (ADS)

Saraiva, A. C. V.; Giménez de Castro, C. G.; Costa, J. E. R.; Selhorst, C. L.; Simões, P. J. A.

2003-08-01

A medição acurada do raio solar em qualquer banda do espectro eletromagnético é de relevância na formulação e calibração de modelos da estrutura e atmosfera solar. Esses modelos atribuem emissão do contínuo do Sol calmo em microondas à mesma região da linha Ha do Hell. Apresentamos a medição do raio solar em UV com imagens do EIT (Extreme Ultraviolet Image Telescope) entre 1996 e 2002, no comprimento de onda 30,9 nm (Ha do Hell), que se forma na região de transição/cromosfera solar. A técnica utilizada para o cálculo do raio UV foi baseada na transformada Wavelet B3spline. Fizemos um banco de dados com 1 imagem por dia durante o período citado. Obtivemos como resultado o raio médio da ordem de 975.61" e uma diminuição do mesmo para o período citado variando em média -0,45" /ano. Comparamos estes dados com os valores obtidos pelo ROI (Radio Observatório de Itapetinga) em 22/48 GHz e Nobeyama Radio Heliograph em 17 GHz mostrando que os raios médios são muito próximos o que indica que a região de formação nessas freqüências é a mesma conforme os modelos. Comparamos os resultados também com outros índices de atividade solar.

Coerência espectroscópica de famílias de asteróides

NASA Astrophysics Data System (ADS)

Mothé Diniz, T.; Roig, F. V.

2003-08-01

As Famílias de asteróides são caracterizadas como agrupamentos de objetos provenientes da quebra por colisão de corpos precursores. Desta forma, seus membros devem preservar relações genéticas que podem ser traduzidas sob a análise de suas características espectrais. Neste trabalho é apresentado o primeiro estudo espectroscópico de todas as famílias de asteróides do cinturão principal. Para tal, a divisão em famílias foi refeita utilizando-se o método HCM com uma base de elementos próprios analíticos (Knezevic e Milani, Jun 2001) e para o estudo espectroscópico foram utilizadas diversas campanhas de observação espectroscópica, tais o S3OS2 e o SMASSII, bem como outros dados disponíveis na literatura. A homogeneidade espectroscópica de cada família foi avaliada através da verificação das classes espectroscópicas presentes, bem como da comparação destes espectros com os de objetos de fundo, localizados na vizinhança da família. Vinte e duas famílias foram analisadas (as que possuíam mais do que 3 membros com espectro) e, dentre as principais conclusões pode-se citar a homogeneidade espectroscópica e, provavelmente mineralógica das famílias de Vesta, Eunomia, Hoffmeister, Dora, Merxia, Agnia, Koronis e Veritas. Esta última em particular, foi tida como uma família não homogênea espectroscopicamente em trabalho anterior (Di Martino et al. 1997). Outro resultado interessante é, por um lado, a aparente falta de homogeneidade dos membros da família de Eos, e por outro sua forte distinção dos objetos de fundo. O oposto ocorre na família de Themis, esta apresentando-se espectroscopicamente compatível com os objetos de fundo, mas com grande homogeneidade taxonômica entre seus membros. Algumas das famílias apresentam asteróides "intrusos" (objetos cujas características físicas não são compatíveis com aquelas dos membros da família) que, de modo geral desaparecem ao se considerarem níveis mais baixos de corte para a divisão da família no HCM, sem prejuízo para o agrupamento dos demais membros.

A correlação índice espectral vs. luminosidade em QSOs e suas implicações

NASA Astrophysics Data System (ADS)

Garcia-Rissmann, A.

2003-08-01

Estudos de variabilidade de núcleos ativos já demonstraram ser comum o fato de seu contínuo óptico/UV tornar-se mais "duro" à medida que a luminosidade aumenta. Essa tendência ocorre tanto de forma individual quanto global, e pode ter implicações importantes (1) para estudos fotométricos de variabilidade conduzidos numa banda fixa no referencial do observador, comparando objetos a diferentes redshifts, e (2) no cálculo da correção K, com consequente impacto na determinação de massas de buracos negros e bojos de galáxias hospedeiras (através da relação de Magorrian). Confirmo aqui as correlações positivas entre o índice espectral e a luminosidade óptica, utilizando dados espectroscópicos de 11 QSOs monitorados no Brasil e no Chile, durante ~2 anos. O estudo é complementado com parâmetros extraídos de espectros e de dados fotométricos públicos de quasares. Destaco ainda as diferenças observadas em tais correlações para objetos do tipo radio-loud e radio-quiet. Este projeto é financiado pelo I. Milênio/CNPq.

Evolución de estrellas enanas blancas en el contexto de una constante de gravitación G variable en el tiempo

NASA Astrophysics Data System (ADS)

Benvenuto, O. G.; Althaus, L. G.; Torres, D. F.

En este trabajo se estudia por primera vez de manera autoconsistente la evolución de las estrellas enanas blancas en el caso de una constante de gravitación G variable en el tiempo. Teniendo en cuenta que: 1) las enanas blancas son en general estrellas muy viejas y 2) su fuente de energía es básicamente de origen térmico y gravitacional, estos objetos son en principio muy adecuados para analizar distintas teorías de gravitación. Los cálculos que aquí presentamos fueron realizados utilizando nuestro código de evolución estelar, el cual calcula la evolución de estrellas enanas blancas por medio del esquema iterativo de Henyey. Dicho código, basado en una descripción física muy detallada, ha sido modificado para tener en cuenta la variación del valor de G. Encontramos que un G variable (decreciente en el tiempo) modifica fuertemente la evolución de las enanas blancas, conduciendo a un rápido enfriamiento de la estrella. Nuestros resultados son comparados con recientes datos observacionales sobre la función de luminosidad de las enanas blancas.

The Portrayal of EFLTeachers in Official Discourse: The Perpetuation of Disdain (La imagen de los profesores de inglés como lengua extranjera en el discurso oficial: la perpetuación del desdén)

ERIC Educational Resources Information Center

Guerrero, Carmen Helena

2010-01-01

The purpose of this article is to offer an interpretation of the images of Colombian English teachers constructed in official discourse, particularly (but not exclusively) in the document "Estándares básicos de competencias en lenguas extranjeras: inglés. Formar en lenguas extranjeras, el reto". This is part of a larger critical…

Observação do abrilhantamento de limbo solar e de estruturas filamentares em 48 ghz utilizando a técnica de regularização adaptativa

NASA Astrophysics Data System (ADS)

Machado, W. R. S.; Mascarenhas, N.; Costa, J. E. R.; Silva, A. V. R.

2003-08-01

O radiotelescópio do Itapetinga tem sido utilizado em campanhas de observações de explosões solares gerando um grande número de mapas diários em 48 GHz como sub-produto destas observações. A resolução espacial do telescópio de 14m do Itapetinga nesta freqüência é de aproximadamente dois minutos de arco. Estruturas de interesse para análise da atmosfera solar quiescente tais como os filamentos e o anel de abrilhantamento do limbo são de dimensão angular moderada da ordem ou ligeiramente menores que a resolução do telescópio. É conhecido que a convolução da função de espalhamento do telescópio, PSF (padrão de ganho do feixe) borra as estruturas de dimensão angular abaixo do HPBW (largura a meia potência do feixe) e portanto é comum a busca por técnicas de restauração que eliminem pelo menos em parte este borramento. Estudamos a restauração destas radioimagens usando a técnica de regularização adaptativa e os resultados ressaltam estas estruturas espaciais de pequeno contraste. O algoritmo da regularização adaptativa faz uso de k imagens, chamadas protótipos, obtidas através da variação de parâmetros de um filtro de regularização. Para controle da qualidade da restauração utilizamos uma imagem de alta resolução espacial obtida na linha H-a e a PSF do Itapetinga para borrá-la. Pequenos desvios, entre a PSF utilizada para o borramento e a PSF utilizada na restauração, produziram alguns desvios notáveis na imagem restaurada porém a adição de ruído nas simulações de restauração foram mais influentes no cálculo da rugosidade da imagem e portanto mais limitante para a restauração. Apresentamos como nosso primeiro resultado uma imagem em 48 GHz com a presença clara do abrilhantamento de limbo que não estava evidente na imagem original e traços de estruturas filamentares, porém ainda sem grande evidência.

Observación espectroscópica de NGC 2442

NASA Astrophysics Data System (ADS)

Agüero, E.; Bajaja, E.; Paolantonio, S.

La galaxia NGC 2442 (SAB(s)bc pec) fue observada con el telescopio de 2,15 m y el espectrógrafo REOSC del CASLEO utilizando el detector CCD Tektronix de 1024 × 1024 pixels de 24 μ m (0,26"). Las exposiciones fueron realizadas con la ranura de 3,3'' × 348'', en el plano focal, ubicadas en seis posiciones, cinco a 40o de áng. de pos. y una a 79o. La mayor parte de las exposiciones se efectuó con la red de 1200 líneas mm-1, a un ángulo de 25,53o cubriendo el rango de λλ 6200 a 6900 con dispersión de 32Å mm-1 y resolución de 2,5 Å. Las relaciones entre las intensidades de las líneas de emisión en el núcleo de NGC 2442 indican que es un LINER lo cual es compatible con la sugerencia de Shobrook de que se trataría de una galaxia Seyfert u otro tipo de galaxia activa. La temperatura y densidad electrónicas nucleares son Te ~14.000 K y Ne ~ 530 cm-3, respectivamente. Una región a 87'' al NE en cambio, donde las intensidades son también altas, presenta características espectrales típicas de una Región HII con Te ~6500 K y Ne ~10 cm-3. La correlación de las intensidades con el CO en 115 GHz y con el continuo en 843 MHz y de las velocidades ópticas con las del CO, a lo largo del eje mayor, son muy buenas. La mayor resolución angular de las observaciones, sin embargo, permite apreciar la existencia de dos componentes de velocidad en el núcleo que pueden corresponder a un anillo en rotación o a un fenómeno de expansión.

Atomic layer deposition of metal oxide by non-aqueous sol-gel chemistry =

NASA Astrophysics Data System (ADS)

Marichy, Catherine

O trabalho apresentado neste manuscrito foi desenvolvido no ambito do programa doutoral intitulado “Deposicao de Camadas Atomicas (ALD) de oxido de metais por sol-gel nao-aquoso”. O objectivo deste trabalho foi a preparacao de hetero-estruturas funcionais por ALD e a sua caracterizacao. Foi desenvolvido um novo processo de deposicao de oxido de estanho a temperatura baixa-moderada, utilizando um metodo ALD nao-aquoso, o qual foi aplicado com sucesso ao revestimento controlado das paredes internas e externas de nanotubos de carbono. Uma vez que a preparacao de nanomateriais funcionais requer uma elevada exatidao do processo de deposicao, foi demonstrada a deposicao precisa de filmes que se adaptem a forma do substrato ou de filmes nano-estruturados constituidos por particulas em varios substratos. Alem disso, foram depositados com grande exatidao varios oxidos de metal em nanotubos de carbono e demonstrou-se a possibilidade de ajustar o revestimento feito por ALD atraves do controlo da funcionalizacao da superficie do substrato nano-estruturado de carbono. As hetero-estruturas obtidas foram posteriormente aplicadas como sensores de gases. O melhoramento verificado na sensibilidade foi atribuido a formacao de heterojuncoes p-n entre o filme de oxido de metais e o suporte. O trabalho desenvolvido tendo como objetivo o controlo do revestimento por ALD atraves da funcionalizacao da superficie do suporte e certamente de interesse para o design de hetero-estruturas funcionais baseadas em substratos de carbono. De facto, durante o ultimo periodo do programa de doutoramento, este conceito foi alargado a funcionalizacao e revestimento com oxidos de metal de fibras de carbono preparadas por “electrospinning”, de forma a melhorar a estabilidade e a atividade eletrocatalitica de catalisadores a base de Pt. Este trabalho foi realizado maioritariamente na Universidade de Aveiro mas tambem na Universidade Nacional de Seul e beneficiou de varias colaboracoes internacionais devido a natureza multidisciplinar da area de investigacao em que esta inserido.

Ensino de Astronomia no Ensino Médio

NASA Astrophysics Data System (ADS)

Albrecht, E.; Voelzke, M. R.

2008-09-01

O presente trabalho de intervenção foi realizado junto a Escola Estadual Colônia dos Pescadores na cidade de Caraguatatuba, com três turmas do terceiro ano do Ensino Médio, envolvendo 119 alunos, 40 na turma A, 40 na turma B e 39 na turma C. A fase inicial foi composta de um questionário de vinte questões dissertativas e objetivas para diagnosticar nos educandos os conceitos prévios sobre Astronomia e, partindo destes realizar uma interferência nas classes envolvidas utilizando metodologias diferentes sendo elas: a tradicional, onde o professor é um repassador de informações, fazendo uso exclusivo de lousa e giz; a segunda também de forma tradicional, porém com auxílio de multimídia para desenvolvimento das aulas e a terceira sob forma de seminários, elaborados e apresentados pelos educandos, no qual o educador faz apenas as intervenções necessárias. Ao final do trabalho as mesmas turmas da fase inicial orientadas pelo mesmo professor responderam novamente ao questionário proposto para diagnosticar dentre as três metodologias utilizadas qual apresentou melhores resultados, sendo os iniciais comparados com os finais. Quando questionados a respeito do significado de Astronomia observou-se inicialmente que os acertos na turma A foram de 100%,turma B: 64%, turma C: 84%, após a intervenção os acertos foram: 100%, 97% e 85% respectivamente, demonstrando claramente uma absorção de conhecimentos. Quando interrogados sobre quantos planetas você acha que existem em nosso Sistema Solar? os acertos foram: turma A: 39%, turma B: 48% e turma C: 46%, após o desenvolvimento do trabalho os acertos foram 94%, 97% e 90% respectivamente.Dentro das respostas obtidas observa-se que a metodologia tradicional com o auxílio de multimeios, aplicada na turma B, demonstrou melhores resultados, foi a mais significativa.

The applicability of the concept of treatment adherence in the context of the Brazilian mental health system.

PubMed

Alvarez, Patricia Elizabeth Sanz de; Rosendo, Ernestina; Alchieri, João Carlos

2016-06-01

To present reflections on the type of research conducted on a treatment adherence among users of Public Mental Health System in Brazil and discuss the applicability of the concept of adherence to treatment in this context. Literature review in SciELO, LILACS, Cochrane Library and PubMed / MEDLINE using the Health Sciences Descriptors (DeCS) treatment, adhesion and "mental health" and the specific vocabulary of the Medical Subject Headings (MeSH) "patient compliance/psychologist" y "mental health". They were included for review the complete texts and theses published between 2007-2012 in Portuguese, English and Spanish. 127 articles were recovered, 32 specifically related to mental health. Eight were excluded for duplicates and after reading the remaining 24 articles were selected for this study 10 conducted in the field of Mental Health in Brazil. No investigations have been identified with focus on adherence to psychosocial treatment offered in public mental health. disregard of the mental health legislation and reinforce the asylum model of assistance. Presentar reflexiones sobre el tipo de investigaciones realizadas en Brasil sobre la adhesión al tratamiento de los usuarios del Sistema Público de Salud Mental y discutir la aplicabilidad del concepto de adhesión al tratamiento en dicho contexto. Revisión bibliográfica en las bases SciELO, LILACS, Biblioteca Cochrane y PubMed/MEDLINE utilizando los descriptores de Ciencias de la Salud (DeCS) adhesión, tratamiento y "salud mental" y el vocabulario específico de Medical Subject Headings (MeSH) "patient compliance/psychologist" y "mental health". Se incluyeron los textos completos y las tesis publicadas entre 2007-2012, en portugués, inglés y español. F1eron recuperados 127 artículos, 32 específicamente de la salud mental. Se excluyeron los 8 duplicados y de los 24 restantes fueron seleccionados para el presente trabajo los 10 realizados en Brasil. No se identificaron enfoques sobre la adhesión al tratamiento de perspectiva psicosocial ofrecido en la red pública de salud mental. Las investigaciones analizadas desconsideran el contexto y la complejidad del tratamiento ofrecido desconociendo la legislación en salud mental vigente y reforzando el modelo de atención asilar.

Self-Programmed Counseling and Self-Programmed Control Manual. A Guide to Self-Image Development with Emphasis on the Chicano Student. Student's Guide = Manual de Sistema de Consejo Auto Programado y Control Auto Programado. Una Guia Para el Desarrollo de La Imagen Propia Con un Enfasis en el Estudiante Chicano.

ERIC Educational Resources Information Center

Mireles, S. Raymond

Self-Programmed Counseling, the instructor's guidance, and Self-Programmed Control (SPC), the student's response, was initially developed by Title III Project USTED (United Students and Teachers for Educational Development) for Mexican American college students on academic probation to use on a non-credit, special group counseling basis. As part…

A distância e o conteúdo estelar da região HII gigante G333.1-0.4 - vínculos para a taxa de formação estelar da galáxia

NASA Astrophysics Data System (ADS)

Figuerêdo, E.; Damineli, A.; Blum, R.; Conti, P.

2003-08-01

Neste trabalho apresentamos imagens de alta resolução angular da região HII gigante G333.1-0.4 obtidas através dos filtros J, H e K no telescópio de 4-m do CTIO. Este trabalho faz parte de um estudo de regiões HII gigantes no infravermelho próximo que tem por objetivo estudar a natureza da formação de estrelas massivas e traçar a estrutura espiral de nossa galáxia. Nossa determinação da distância é baseada no método da paralaxe espectroscópica de estrelas OB localizadas na seqüência principal de idade zero (ZAMS) do Diagrama HR. No caso de G333.1-0.4, a magnitude aparente das estrelas localizadas na ZAMS indica que a distância não pode ser maior do que o limite inferior determinado por técnica rádio (2,8 kpc). Resultados semelhantes foram encontrados para regiões estudadas anteriormente, reforçando a idéia de que a taxa de formação estelar na Via Láctea é menor do que o determinado a partir de dados rádio. Nossos resultados mais recentes sobre o conteúdo estelar de G333.1-0.4 revelaram vários objetos que possuem cores bastante avermelhadas (H-K > 2,0). Nós identificamos estes objetos usando os diagramas cor-cor e cor-magnitude dos aglomerados. Estes objetos apresentam um forte excesso em emissão na banda K e possivelmente se tratam de estrelas do tipo OB envolvidas por um disco/envelope circumestelar espesso. O estudo da função de massa inical desta região, em conjunto com resultados de nossos trabalhos anteriores, aponta para uma IMF independente da posição galática. A contagem de estrelas nos fornece um valor para o número de fótons no contínuo de Lyman que corrobora com a afirmação de que G333.1-0.4 se encontra mais próxima da menor distância determinada por rádio.

Projeto observatórios virtuais: educação através de telescópios robóticos

NASA Astrophysics Data System (ADS)

Santana, P. H. S.; Shida, R. Y.

2003-08-01

O principal objetivo do projeto Observatórios Virtuais é o ensino na área de ciências através de atividades práticas desenvolvidas em colaboração entre instituições de pesquisa em astronomia e escolas de ensino médio e fundamental. Este ano deverá ser concluída a implantação do programa piloto de estudos, pesquisas e observação astronômica direta, com utilização em tempo real de telescópios robóticos, que assim funcionarão como "observatórios virtuais". O objetivo pedagógico das atividades práticas baseadas nas imagens atronômicas é desenvolver as habilidades e competências dos alunos no uso do método científico. Para isso, serão realizados projetos interdisciplinares, a partir de observações astronômicas, já que a astronomia é uma área interdisciplinar por excelência. Essas atividades terão níveis diferenciados de complexidade, que podem ser adequados aos vários graus do ensino e realidades regionais. Será dada ênfase ao desenvolvimento e aplicação em São Paulo, onde atua a equipe do IAG/USP. Como resultados apresentados no presente trabalho, temos a criação de um software em português para o processamento de imagens obtidas através de CCDs e a elaboração de material para as atividades educacionais relacionadas.

Estudio de la influencia de la refrigeracion con aire de forma natural e inducida en el comportamiento de instalaciones fotovoltaicas

NASA Astrophysics Data System (ADS)

Mazon Hernandez, Rocio

The aim is to analyse the negative influence of high panel temperatures on electrical production when they are placed on steel roofs of industrial buildings and greenhouse roofs. Different configurations have been tested in order to allow cooling of photovoltaic panels to decrease panel temperature and improve electrical performance. To research this problem two experimental facilities have been built. The first facility includes two panels fixed on a structure. A panel is integrated on a parallel steel plate which does not allow sufficient cooling. Between both surfaces, there is an open air channel in which an air flow is created by the chimney effect thus cooling the panel by natural convection or inducing air, using a fan, by forced convection. The other panel has not any plate underneath it and is used as a referent. The electrical behaviour of the integrated panel has been studied for different air gaps and induced velocities, being also compared with the reference panel. An experimental model was developed to establish correlations which allow determine the panel temperature depending on the influential variables on the cooling ability. This research also analyses the data of a working solar plant, with the same panel model, obtaining the correlations between electrical variables and panel temperature. A comparison with the electrical behaviour in the experimental facility and the solar plant is also presented. The second experimental facility is a replica of a photovoltaic greenhouse. It consists of four photovoltaic panels placed on the plastic roof, providing an open and divergent channel between both surfaces thus creating an air flow by natural convection. This research studies the effect of high temperatures within the greenhouse which is transferred by the roof and thus affects the electrical production. In addition, two air gaps were used and the effect of adding insulating material to the plastic roof was studied. The electrical variables of the panels are analysed to compare and select the best configuration. The presented research provides a deep knowledge of how they work as well as information and results for an improvement in future designs of building integrated photovoltaic systems. Este estudio se centra en analizar la influencia negativa de la temperatura en la produccion electrica de paneles fotovoltaicos al estar emplazados sobre cubierta de acero, como sucede en naves industriales y sobre un invernadero. Se estudian diferentes configuraciones que permitan refrigerar los paneles, reduciendo su temperatura y mejorar su rendimiento. Para abordar este problema, se han construido dos instalaciones experimentales, fieles a plantas solares en funcionamiento. Una instalacion engloba dos paneles fotovoltaicos sobre estructura fija al suelo. Uno de los paneles esta integrado sobre una superficie paralela y metalica. Entre ambas superficies existe un espacio que posibilita circular aire, permitiendo refrigerar el panel por conveccion natural, o conveccion forzada impulsando el aire con un ventilador. El otro panel, libre por su cara posterior y se ha considerado de referencia. Se ha estudiado el comportamiento del panel integrado sobre cubierta para diferentes secciones de aire y velocidades inducidas, comparandolo con el panel de referencia. Se ha desarrollado un modelo experimental que nos permite determinar la temperatura del panel en funcion de las variables que influyen en su refrigeracion. Adicionalmente, se han analizado los datos de una planta solar en funcionamiento, con paneles de igual caracteristicas, obteniendo correlaciones entre la temperatura del panel y las variables electricas y comparandolos con las obtenidas en la instalacion experimental. La segunda instalacion experimental reproduce parte de una instalacion solar sobre un invernadero, formada por cuatro paneles fotovoltaicos colocados sobre el plastico del invernadero, existiendo un canal divergente entre ambas superficies. Se estudia la influencia de las altas temperaturas en el interior del invernadero sobre la produccion electrica de los paneles, decido a la transferencia de calor del interior del invernadero. Ademas, se han ensayado dos separaciones diferentes y para cada una se ha comparado con la misma, utilizando un aislante sobre la cubierta. El estudio realizado sobre ambas instalaciones ha proporcionado un conocimiento profundo del funcionamiento de cada una de ellas, asi como informacion valida para una mejora de futuros disenos de instalaciones fotovoltaicas sobre cubiertas.

Desenvolvimento de modelo clínico para predição da possibilidade de identificação da artéria de Adamkiewicz por angiotomografia

PubMed Central

Amato, Alexandre Campos Moraes; Parga, José Rodrigues; Stolf, Noedir Antônio Groppo

2018-01-01

Resumo Contexto Diferenças morfológicas da artéria de Adamkiewicz (AKA) entre a população portadora e não portadora de doença aórtica têm importância clínica, influenciando as complicações neuroisquêmicas da medula espinhal em procedimentos operatórios. Ainda não é conhecida a correlação entre parâmetros clínicos e a previsibilidade da identificação dessa artéria pela angiotomografia. Objetivo Desenvolver um modelo matemático que, através de parâmetros clínicos correlacionados com aterosclerose, possa prever a probabilidade de identificação da AKA em pacientes submetidos a angiotomografias. Método Estudo observacional transversal utilizando banco de imagens e dados de pacientes. Foi feita análise estatística multivariada e criado modelo matemático logit de predição para identificação da AKA. Variáveis significativas foram utilizadas na montagem da fórmula para cálculo da probabilidade de identificação. O modelo foi calibrado, e a discriminação foi avaliada pela curva receiver operating characteristic (ROC). A seleção das variáveis explanatórias foi guiada pela maior área na curva ROC (p = 0,041) e pela significância combinada das variáveis. Resultados Foram avaliados 110 casos (54,5% do sexo masculino, com idade média de 60,97 anos e etnia com coeficiente B -2,471, M -1,297, N -0,971), com AKA identificada em 60,9%. Índice de massa corporal: 27,06 ± 0,98 (coef. -0,101); fumantes: 55,5% (coef. -1,614/-1,439); diabéticos: 13,6%; hipertensos: 65,5% (coef. -1,469); dislipidêmicos: 58,2%; aneurisma aórtico: 38,2%; dissecção aórtica: 12,7%; e trombo mural: 24,5%. Constante de 6,262. Fórmula para cálculo da probabilidade de detecção: (e−(Coef. Etnia+(Coef. IMC×IMC)+Coef.fumante+Coef.HAS+Coef.dislip+Constante)+1)−1 . O modelo de predição foi criado e disponibilizado no link https://vascular.pro/aka-model . Conclusão Com as covariáveis etnia, índice de massa corporal, tabagismo, hipertensão arterial e dislipidemia, foi possível criar um modelo matemático de predição de identificação da AKA com significância combinada de nove coeficientes (p = 0,042). PMID:29930677

Risk management in providing specialized care for people living with AIDS.

PubMed

Leadebal, Oriana Deyze Correia Paiva; Medeiros, Leidyanny Barbosa de; Morais, Kalline Silva de; Nascimento, João Agnaldo do; Monroe, Aline Aparecida; Nogueira, Jordana de Almeida

2016-01-01

Analyzing the provision of actions related to managing clinical risk in managing specialized care for people living with AIDS. A cross-sectional study carried out in a reference outpatient clinic in Paraíba, with a sample of 150 adults with AIDS. Data were collected through primary and secondary sources using a structured questionnaire, analyzed using descriptive statistics, multiple correspondence analysis and logistic regression model to determine the association between "providing care" and "clinical risk." Actions with satisfactory provision express a biological care focus; the dimensions that most contributed to a satisfactory assessment of care provision were "clinical and laboratory evaluations" and "prevention and self-care incentivization"; 45.3% of participants were categorized into high clinical risk, 34% into average clinical risk, and 20.7% into low clinical risk; a positive association between providing care and clinical risk was found. The need to use risk classification technologies to direct the planning of local care provision became evident considering its requirements, and thus qualifying the care provided in these areas. Analisar a oferta de ações relacionadas ao manejo de risco clínico na gestão do cuidado especializado a pessoas vivendo com aids. Estudo transversal realizado em ambulatório de referência na Paraíba, com amostra de 150 adultos com aids. Os dados foram coletados por meio de fontes primárias e secundárias utilizando-se de formulário estruturado, e analisados através de estatística descritiva, análise de correspondência múltipla e modelo de regressão logística para averiguar a associação entre "oferta" e "risco clínico". As ações de oferta satisfatória expressam foco biologicista do cuidado; as dimensões que mais contribuíram para o julgamento satisfatório da oferta foram "avaliação clínica e laboratorial" e "prevenção e estímulo ao autocuidado"; 45,3% dos participantes foram categorizados em risco clínico alto, 34% em risco clínico médio, e 20,7% em risco clínico baixo; e verificou-se associação positiva entre oferta e risco clínico. Ficou evidente a necessidade da utilização de tecnologias de classificação de risco para direcionar o planejamento da oferta local, considerando-se as necessidades, e assim qualificar o cuidado produzido nestes espaços.

On efeito do achatamento nos pontos de equilíbrio e na dinâmica de sistemas coorbitais

NASA Astrophysics Data System (ADS)

Mourão, D. C.; Winter, O. C.; Yokoyama, T.

2003-08-01

Neste trabalho analisamos o efeito do achatamento do corpo principal nos pontos de equilíbrio lagrangianos e na configuração de órbitas girino-ferradura. Enfatizamos os sistemas coorbitais de satélites de Saturno, pois se encontram em relativa proximidade com o planeta, em que o efeito do achatamento se torna mais evidente. O estudo é dividido em três etapas independentes. Na primeira fase analisamos as equações de movimento do problema restrito de três corpos considerando o efeito do achatamento, e através do balanceamento de forças buscamos a nova configuração dos pontos de equilíbrio lagrangianos. Concluímos, nesta etapa, que os pontos de equilíbrio estáveis apresentam um pequeno deslocamento definido pelo parâmetro de achatamento, não podendo ser mais representados por triângulos eqüiláteros. Aplicamos este resultado aos satélites coorbitais de Tetis e Dione, encontrando as posições de equilíbrio levemente deslocadas em relação ao caso sem achatamento. Na segunda fase visamos o sistema Saturno-Jano-Epimeteu, que por se tratar de um sistema de massas comparáveis, optamos por desenvolver as equações de Yoder et al (Icarus 53, pág 431-443, 1983), que permitem determinar os pontos de equilíbrio e a amplitude de oscilação angular das órbitas girino-ferradura para o problema não-restrito de três corpos, porém, no nosso estudo consideramos o efeito do achatamento do corpo principal nestas equações. Encontramos que a distância angular entre satélites, quando em posição de equilíbrio estável, diminui quanto maior for o parâmetro de achatamento do corpo principal. Além disso, a órbita de transição girino-ferradura possui largura angular menor em relação ao caso sem achatamento. Por fim, realizamos integrações numéricas para os casos reais de coorbitais de Saturno comparando com os resultados analíticos. Nestas integrações simulamos diversas órbitas girino-ferradura com diferentes parâmetros de achatamento, utilizando condições iniciais corrigidas para a presença do achatamento.

Establishing the Empirical Relationship Between Non-Science Majoring Undergraduate Learners' Spatial Thinking Skills and Their Conceptual Astronomy Knowledge. (Spanish Title: Estableciendo Una Relación Empírica Entre el Razonamiento Espacial de los Estudiantes de Graduación de Carreras no Científicas y su Conocimento Conceptual de la Astronomía.) Estabelecendo Uma Relação Empírica Entre o RacioCínio Espacial dos Estudantes de Graduação EM Carreiras Não Científicas e Seu Conhecimento Conceitual da Astronomia

NASA Astrophysics Data System (ADS)

Heyer, Inge; Slater, Stephanie J.; Slater, Timothy F.

2013-12-01

The astronomy education community has tacitly assumed that learning astronomy is a conceptual domain resting upon spatial thinking skills. As a first step to formally identify an empirical relationship, undergraduate students in a non-major introductory astronomy survey class at a mediumsized, Ph.D. granting, mid-western US university were given pre- and post-astronomy conceptual diagnostics and spatial reasoning diagnostics, Instruments used were the "Test Of Astronomy Standards" and "What Do You Know?" Using only fully matched data for analysis, our sample consisted of 86 undergraduate non-science majors. Students' normalized gains for astronomy surveys were low at .26 and .13 respectively. Students' spatial thinking was measured using an instrument designed specifically for this study. Correlations between the astronomy instruments' pre- to post-course gain scores and the spatial assessment instrument show moderate to strong relationships suggesting the relationship between spatial reasoning and astronomy ability can explain about 25% of the variation in student achievement. La comunidad de educación en astronomía ha supuesto de forma tácita que el aprendizaje de la astronomía consiste en un dominio conceptual fundamentado en el razonamiento espacial. Como un primer paso para identificar formalmente una relación empírica entre estas dos cosas, utilizamos como muestra los estudantes de graduación de carreras no científicas de un curso experimental en una universidad norteamericana del medioeste de porte mediano con programa de Doctorado em curso, en el cual estos estudiantes se sometieron a un diagnóstico de razonamiento espacial y conceptos astronómicos antes e después del mismo. Las herramientas utilizadas fueron el Test Of Astronomy Standards (TOAST) y el cuestionario What do you know? Utilizando solo los datos completamente consistentes para este análisis, nuestra muestra consistió en 86 estudantes de graduación. Las mejoras, depués de normalizadas, en el desempeño de los estudiantes en estos dos asuntos foram pequenas, 0.26 e 0.13 respectivamente. El razonamiento espacial de los estudiantes fue medido utilizando un instrumento específico desarrollado para este trabaljo. Las correlaciones entre los resultados de los tests astronómicos y este instrumento específico, antes y después del curso mostraron una relación entre moderada y fuerte, sugiriendo que la relación entre el razonamiento espacial y el conocimiento astronómico puede explicar hasta un 25% de la variación em el desempeño de los estudiantes. A comunidade da educação em astronomia tem suposto de forma implícita que o aprendizado da astronomia consiste em um domínio conceitual fundamentado no raciocínio espacial. Como um primeiro passo para identificar formalmente uma relação empírica entre estas duas coisas, utilizamos como amostra os estudantes de graduação de carreiras não científicas de um curso exploratório em uma universidade norte-americana do meio-oeste de médio porte com programa de Doutorado em andamento, onde estes estudantes foram submetidos a um diagnóstico de raciocino espacial e conceitos astronômicos antes e depois do mesmo. As ferramentas utilizadas foram o Test Of Astronomy Standards (TOAST) e o questionário What do you know? Utilizando somente dados completamente consistentes para esta análise, nossa amostra consistiu de 86 estudantes de graduação. As melhoras, depois de normalizadas, do desempenho dos estudantes nos dois quesitos foram pequenas, 0.26 e 0.13 respectivamente. O raciocínio espacial dos estudantes foi medido utilizando um instrumento específico desenhado para este trabalho. As correlações entre os resultados dos testes astronômicos e este instrumento específico antes e depois do curso mostraram uma relação entre moderada e forte, sugerindo que a relação entre o raciocínio espacial e o conhecimento astronômico pode explicar até um 25% na variação no desempenho dos estudantes.

AIDS and jail: social representations of women in freedom deprivation situations.

PubMed

Trigueiro, Débora Raquel Soares Guedes; Almeida, Sandra Aparecida de; Monroe, Aline Aparecida; Costa, Gilka Paiva Oliveira; Bezerra, Valéria Peixoto; Nogueira, Jordana de Almeida

2016-01-01

To graspthe AIDS social representations built by freedom-deprived women. Descriptive study with a quali-quantitative approach that involved 174 convicted women in a women's prison in a capital city of the Brazilian northeastern region. Aword-association test was applied in October and November 2014, using AIDS as a stimulus. The corpuswas processed usingIramuteq software. Descending Hierarchical Classification and Correspondence Factor Analysis were applied. The content that comprises the social representation of AIDS was influenced by the prison context, which was pervaded by a lack of assistance, lack of knowledge, discrimination, and suffering that disclosed vulnerability to HIV/AIDS factors such as unprotected sex and object sharing. This underlines the stigma and fear of the illness, in addition to favoring and supporting negative feelings and a sense of rejection. To consider the use of this representational amalgam to ensure a comprehensive, contextualized care can help redirect practices, motivate self-care practices, and reduce prejudiced attitudes. Apreenderas representações sociais sobre a aids construídas por mulheres privadas de liberdade. Estudo descritivo, com abordagem quali-quantitativa que envolveu 174 apenadas de Presídio Feminino situado em capital do nordeste brasileiro. Aplicou-se o Teste de Associação Livre de Palavras, em outubro e novembro de 2014, utilizando-se do estímulo aids. O corpus foi processado pelo software Iramuteq, sendo efetuadas a Classificação Hierárquica Descendente e Análise Fatorial de Correspondência. Os conteúdos que compõem a representação social sobre aids são influenciados pelo contexto prisional, permeado dedesassistência, desconhecimento, discriminação e condições de sofrimento, revelando fatores de vulnerabilidade ao HIV/Aids como atividade sexual desprotegida e compartilhamento de objetos; reiterando o estigma e o temor à doença; e favorecendo e sustentando sentimentos negativos e de rejeição. Considerar este amálgama representacional na garantia de um cuidado integral e contextualizado pode contribuir para redirecionar práticas, motivar condutas de autocuidado e reduzir atitudes preconceituosas.

Falls in long-term care institutions for elderly people: protocol validation.

PubMed

Baixinho, Cristina Rosa Soares Lavareda; Dixe, Maria Dos Anjos Coelho Rodrigues; Henriques, Maria Adriana Pereira

2017-01-01

To validate the content of a fall management risk protocol in long-term institutions for elderly people. Methodological, quanti-qualitative study using the Delphi technique. The tool, based on the literature, was sent electronically to obtain consensus among the 14 experts that meet the defined inclusion criteria. The 27 indicators of the protocol are organized in three dimensions: prepare for the institutionalization (IRA=.88); manage the risk of falls throughout the institutionalization (IRA=.9); and lead the communication and formation (IRA=1), with a CVI=.91. Two rounds were performed to get a consensus superior to 80% in every item. The values obtained in the reliability test (>0.8) show that the protocol can be used to meet the intended goal. The next step is the clinic validation of the protocol with residents of long-term care institutions for elderly people. Validar o conteúdo de um protocolo para a gestão do risco de queda em Instituições de Longa Permanência para Idosos. Estudo metodológico, de abordagem quantiqualitativa, utilizando a técnica de Delphi. O instrumento, construído com base na literatura, foi enviado por via electrónica, para obter consenso entre os 14 peritos que respeitam os critérios de inclusão definidos. Os 27 indicadores do protocolo estão organizados em três dimensões: Preparar a Institucionalização (IRA=,88); Gerir o Risco de Queda ao longo da Institucionalização (IRA=,9) e Liderar a comunicação e formação (IRA=1), com um CVI=,91. Foram efetuadas duas rodadas para se obter consenso superior a 80% em todos os itens. Os valores obtidos no teste de fidedignidade (>0,8) atestam que o protocolo pode ser utilizado para atingir o fim que se pretende. A próxima etapa é a validação clínica do protocolo com idosos residentes em Instituições de Longa Permanência para Idosos.

Evolução química de galáxias HII anãs

NASA Astrophysics Data System (ADS)

Ferraresi, M., Jr.; Cuisinier, F.; Telles, E.

2003-08-01

Galáxias HII anãs são galáxias de baixa massa, com alto conteúdo de gás, e se encontram em uma fase intensa de formação estelar. A taxa de formação estelar está tão alta nestas galáxias que não pode ter se mantido durante sua vida inteira. O tempo máximo de duração do episódio atual de formação estelar deve ser no máximo de algumas dezenas de milhões de anos, bem inferior à idade destas galáxias. Isto leva naturalmente a idéia de que já aconteceram surtos anteriores. Abundâncias químicas oferecem uma ferramenta poderosa para investigar a história evolutiva destas galáxias, porque aumentam de geração em geração estelar. O hidrogênio, o oxigênio, o nitrogênio produzem algumas das linhas mais importantes em um gás foto-ionizado, permitindo a determinação das abundâncias destes elementos facilmente. A dispersão das abundâncias em oxigênio e nitrogênio é significativa, sendo maior que os erros observacionais. O oxigênio é produzido em estrelas massivas, que explodem quase instâneamente, enquanto o nitrogênio é produzido em estrelas de massa intermediária, que só o liberam depois de um atraso de @ 500 mihões de anos. Construímos um modelo de evolução química semi-analítico, utilizando rendimentos empíricos baseados nas abundâncias observadas destes dois elementos. Conseguimos através deste modelo rudimentar explicar nas galáxias de mais baixas metalicidades as abundâncias de oxigênio e de nitrogênio, assim como a dispersão dos dados observacionais devida a formação estelar descontínua, e isto com um número baixo de surtos (1 ou 2, no máximo 3).

Detecção inesperada de efeitos de lentes fracas em grupos de galáxias pouco luminosos em raios-X

NASA Astrophysics Data System (ADS)

Carrasco, R.; Mendes de Oliveira, C.; Sodré, L., Jr.; Lima Neto, G. B.; Cypriano, E. S.; Lengruber, L. L.; Cuevas, H.; Ramirez, A.

2003-08-01

Obtivemos, como parte do programa de verificação científica do GMOS Sul, imagens profundas de três grupos de galáxias: G97 e G102 (z~0,4) e G124 (z = 0,17). Esses alvos foram selecionados a partir do catálogo de fontes extensas de Vikhlinin (1998), por terem luminosidades em raios X menores que 3´1043 ergs s-1, valor cerca de uma ou duas ordens de grandeza inferior ao de aglomerados de galáxias. O objetivo primário dessas observações é o estudo da evolução de galáxias em grupos. Grupos são ambientes menos densos que aglomerados, contêm a grande maioria das galáxias do Universo mas que, até o momento, foram estudados detalhadamente apenas no Universo local (z~0). Com esses dados efetuamos uma análise estatística da distorção na forma das galáxias de fundo (lentes gravitacionais fracas) como forma de inferir o conteúdo e a distribuição de massa nesses grupos apesar de que, em princípio, esse efeito não deveria ser detectado uma vez que os critérios de seleção adotados previlegiam sistemas de baixa massa. De fato, para G124 obtivemos apenas um limite superior para sua massa que é compatível com sua luminosidade em raios X. De modo contrário e surpreendente, os objetos G102 e G097, aparentam ter massas que resultariam em dispersões de velocidade maiores que 1000 km s-1, muito maiores do que se espera para grupos de galáxias. Com efeito, para G097 obtivemos, a partir de dados do satélite XMM, uma estimativa para a temperatura do gás intragrupo de kT = 2,6 keV, que é tipica de sistemas com dispersões de velocidade de ~ 600 km s-1, bem característica de grupos. Essas contradições aparentes entre lentes fracas e raios X podem ser explicadas de dois modos: i) a massa obtida por lentes estaria sobreestimada devido à superposição de estruturas massivas ao longo da linha de visada ou ii) a temperatura do gás do meio intra-grupo reflete o potencial gravitacional de estruturas menores que estariam se fundindo para formar uma estrutura maior.

Operational tools and applications of EO satellite data to retrieve surface fluxes in semi-arid countries

NASA Astrophysics Data System (ADS)

Tanguy, Maliko

The objective of the thesis is to develop and evaluate useful tools and applications of Earth Observation (EO) satellite data to estimate surface fluxes in semi-arid countries. In a first part (Chapter 4), we assess the performance of a new parameterisation scheme of ground heat flux (G) to be used in remote sensing (RS) evapotranspiration (ET) estimation methods. The G-parameterisation optimized with AMMA flux data performs well and improves the sensible heat flux (H) and ET retrieved by means of the triangle method (Jiang & Islam, 2001). In a second part (Chapter 5), the triangle method is compared with ET estimated by means of a land surface model (JULES). An attempt is made to calibrate JULES using the triangle method through Monte Carlo simulations, but the two methods supply rather different results, indicating that further intercomparison tasks should be carried out to assess the performance of RS-based algorithms and land surface models in estimating the components of the land surface energy balance. Chapter 6 presents a set of operational examples for retrieving surface fluxes using RS data. The first example is the study of temporal evolution of ET-maps in Western Africa under monsoonal influence. In a second example, we apply the new scheme proposed in Chapter 4 to retrieve and analyse the long term evolution (2000-2009) of the surface energy balance components, G, H and ET at several sites of the Segura Basin (S-E Spain) using MODIS-Terra data (land surface temperature and NDVI). Temporal and spatial distribution of evapotranspiration reveals different controls on ET. (Chapter 6). In the last example, MODIS-Aqua Sea Surface Temperature (SST) is used to validate a mathematical model to retrieve surface fluxes in a Mediterranean coastal lagoon (Mar Menor, S-E Spain). El objetivo de esta tesis es de desarrollar y evaluar herramientas y aplicaciones de la teledetección para estimar flujos de superficie en zonas semiáridas. En una primera parte (Capítulo 4), se evalúa la fiabilidad de una nueva parametrización para estimar el flujo de calor en el suelo (G) con el fin de ser utilizado en métodos de estimación de la evapotranspiración (ET) usando datos de teledetección. La parametrización de G se optimiza usando datos de flujo de energía obtenido durante las campañas del proyecto AMMA, y muestra buenos resultados y una mejora de las estimaciones del flujo de calor sensible (H) y de ET cuando se utiliza conjuntamente con el método del triángulo (Jiang & Islam, 2001). En una segunda parte (Capítulo 5), el método del triángulo se compara con valores de ET estimado por un modelo de superficie terrestre (JULES). Se intenta calibrar JULES usando el método del triángulo mediante simulaciones de Monte Carlo, pero los dos métodos muestran resultados muy diferentes, indicando que se necesita tareas de comparación profundizadas para poder evaluar la eficacia de estos modelos (de superficie terrestre y basados en la teledetección) para estimar los flujos de energía a la superficie. El capítulo 6 presenta un conjunto de ejemplos de aplicaciones operacionales para estimar los flujos de superficie usando datos de teledetección. El primer ejemplo consiste en el estudio de la evolución temporal de mapas de ET en África occidental bajo la influencia del monzón africano. En el segundo ejemplo, se aplica la nueva parametrización de G descrita en el capítulo 4 para calcular y analizar la evolución a largo plazo (2000-2009) de los componentes del balance de energía a la superficie, G, H y ET, en diferentes puntos de la cuenca del río Segura (Sureste español) utilizando datos del sensor MODIS-Terra (temperatura superficial y NDVI). La distribución temporal y espacial de ET revela diferentes controles sobre ET. En el último ejemplo, datos de temperatura superficial del mar del sensor MODIS-Aqua se utilizaron para validar un modelo matemático para calcular los flujos superficiales de una laguna costera del Mediterráneo (Mar Menor en el Sureste español).

Pity and Fear: Myths and Images of the Disabled in Literature Old and New = Lastima y Miedo: Mito e Imagenes del Invalido en la Literatura Antigua y Moderna = La Pitie et la Peur: Mythes et Images des Infirmes dans la Literature Ancienne et Moderne. Proceedings of a Literary Symposium Sponsored by ICD-International Center for the Disabled in Collaboration with the United Nations (October 27, 1981).

ERIC Educational Resources Information Center

Fiedler, Leslie A.; And Others

The booklet (also in Spanish and French) presents an edited transcript of a conference dealing with images of the disabled in literature and the arts. L. Fielder's keynote paper traces the evolving role of disabled people by examining, in films and novels, the role of myth in society, the debilitating use of euphemisms, the unsatisfactory attempts…

The Role of Sex and Mating Status in the Expansion Process of Arhopalus rusticus (Coleoptera: Cerambycidae)-an Exotic Cerambycid in Argentina.

PubMed

Grilli, Mariano Pablo; Fachinetti, Romina

2017-06-01

In Córdoba province, central Argentina, there is an area of introduced pine trees, in which an invading Cerambycid, Arhopalus rusticus (L.), was detected in this region for the first time in 2006. The species has since expanded its range until it now occupies the whole area. Arhopalus rusticus is a common species in pine forests of the northern hemisphere. In this paper, we analyze how sex and mating status affects flight performance and the potential distribution of this species. The study was performed with individuals collected from introduced pine forests in the center-west of Córdoba Province (Argentina). The dispersal capability of A. rusticus was determined by measuring flight speed and distance traveled by recently emerged mated and unmated A. rusticus in flight mills. Data of preflight body weight, postflight body weight, body length, and elytron size were obtained from the individuals that were flown in the flight mill. We found that females had a greater body length, weighed more, had longer elytra, and were stronger flyers than males. We also found that mated individuals flew faster and longer distances than unmated individuals, and consumed a smaller fraction of their body weight. A positive ratio was observed between elytra size and flight speed. A map of males' and females' dispersal distances was produced for the study region, using the adjusted dispersal distance distribution of males and females. The flight performance showed that, as females disperse after copulation, they increase the chances of establishing the species in unoccupied areas.En la provincia de Córdoba, Argentina, hay una importante área de pinos implantados. En esta región durante el año 2006 se detectó por primera vez a Arhopalus rusticus (L.), un Cerambycidae invasor. A. rusticus es una especie común en los bosques de pino del hemisferio norte. En este trabajo analizamos de qué manera el sexo y el estado de apareamiento afectan el desempeño de vuelo y la distribución potencial de esta especie. Utilizamos individuos recolectados de los bosques de pino implantados en la región centro oeste de la provincia de Córdoba (Argentina). La capacidad de dispersión de Arhopalus rusticus se determinó haciendo volar individuos recién emergidos en un molino de vuelo. Se registró el peso previo y posterior al vuelo, el largo del cuerpo y el tamaño del élitro. Las hembras fueron mejores voladoras, más largas, más pesadas, con élitros más largos que los machos. Observamos diferencias entre el potencial de dispersión dependiendo del estado de apareamiento de los individuos. Los individuos apareados volaron más rápido y mayores distancias que los individuos no apareados y consumieron una menor fracción de su peso corporal. Se observó una relación positiva entre el tamaño del élitro y la velocidad de vuelo. Se generó un mapa de las distancias de dispersión potencial de los machos y de las hembras para la región de estudio utilizando las distribuciones de las distancias obtenidas del molino de vuelo. La dispersión post copulación incrementa las chances de que la especie se establezca en zonas no ocupadas. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Labeling and defining severe and enduring anorexia nervosa: A systematic review and critical analysis.

PubMed

Broomfield, Catherine; Stedal, Kristin; Touyz, Stephen; Rhodes, Paul

2017-06-01

With anorexia nervosa (AN) having various presentations, attention has been directed towards particularly durable forms of the condition in both research and clinical contexts. A major hindrance in terms of advancing the field is the inconsistent labeling and defining of this subgroup. This has two implications; first, the inconsistent recruitment of participants when researching this sample, and second, the misdiagnosing of patients who may or may not have a durable course of the disease. The current research had the purpose of providing an overview of the current labels and criteria used for defining cases of severe and enduring AN, and critically analysing the implications of these findings. In accordance with PRISMA guidelines, a literature search was conducted using four electronic databases (PsycINFO, MEDLINE, Web of Science and Scopus) in order to identify 32 records that met the standards stipulated by the criteria. Data extraction included explicit labeling, the definition or criteria used to describe the subgroup, along with participant age and study design. It was found that the terms chronic and severe and enduring were the most commonly used adjectives when referring to this subgroup. In terms of criteria, illness duration and the number of previously failed treatment attempts were the most common defining features within the literature. It is the aim of the authors to inspire further research into what is the most appropriate label and defining features for the subgroup in order to facilitate a better approach and outcome for the individuals affected. Objetivo Con la Anorexia Nervosa (AN) teniendo varias presentaciones, tanto en la investigación como en los contextos clínicos, la atención se ha dirigido particularmente hacia las formas duraderas de esta condición. Un obstáculo importante en términos de avanzar en el campo es la inconsistencia en el etiquetado y definición de este subgrupo. Esto tiene dos implicaciones; Primero, el inconsistente reclutamiento de participantes cuando se investiga esta muestra, y segundo, el diagnóstico equivocado de pacientes que pueden o no tener un curso duradero de la enfermedad. La presente investigación tiene el propósito de proporcionar una visión general de las etiquetas actuales y los criterios utilizados para definir los casos de AN severa y duradera, y analizar críticamente las implicaciones de estos hallazgos. Método: De acuerdo con las guías PRISMA, se realizó una búsqueda en la literatura utilizando cuatro bases de datos electrónicas (PsycINFO, MEDLINE, Web of Science y Scopus) para identificar 32 artículos que cumplían con los estándares estipulados por los criterios. La extracción de datos incluyó el etiquetado explícito, la definición o criterio utilizado para describir este subgrupo, junto con la edad del participante y el diseño del estudio. Resultados: Se encontró que los términos crónico, severo y duradero eran los adjetivos más comúnmente utilizados cuando se referían a este subgrupo. En términos de criterios, la duración de la enfermedad y el número de intentos de tratamiento previamente fallidos fueron las características definitorias más comunes dentro de la literatura. Discusión: Uno de los objetivos de los autores es inspirar a que se realice más investigación en torno a cuál sería el etiquetado y la definición más apropiados para este subgrupo y así facilitar un mejor abordaje y resultados para los individuos afectados. © 2017 Wiley Periodicals, Inc.

Development, health, and international policy: the research and innovation dimension.

PubMed

Buss, Paulo Marchiori; Chamas, Claudia; Faid, Miriam; Morel, Carlos

2016-11-03

This text main objective is to discuss development and health from the perspective of the influence of global health governance, using as the tracer the dimension of research, development, and innovation policies in health, which relate to both important inputs for the health system, like drugs and medicines, vaccines, diagnostic reagents, and equipment, and innovative concepts and practices for the improvement of health systems and public health. The authors examine the two main macro-processes that influence development and health: the post-2015 Development Agenda and the process under way in the World Health Organization concerning research and development, intellectual property, and access to health inputs. The article concludes, first, that much remains to be done for the Agenda to truly represent a coherent and viable international political pact, and that the two macro-processes related to innovation in health need to be streamlined. But this requires democratization of participation by the main stakeholders - patients and the general population of the poorest countries - since this is the only way to overcome a "zero sum" result in the clash in the current debates among member State representatives. Resumo: O objetivo central deste texto é discutir desenvolvimento e saúde sob a ótica da influência da governança da saúde global, utilizando como traçador a dimensão das políticas de pesquisa, desenvolvimento e inovação em saúde, que se referem, de um lado, a insumos importantes para o sistema de saúde - como fármacos e medicamentos, vacinas, reativos para diagnóstico e equipamentos e, de outro, a conceitos e práticas inovadoras para o aperfeiçoamento dos sistemas de saúde e da saúde pública. Examina os dois principais macroprocessos que influenciam o desenvolvimento e a saúde: a Agenda do Desenvolvimento para o pós-2015 e o processo sobre pesquisa e desenvolvimento, propriedade intelectual e acesso a insumos em saúde em curso na Organização Mundial da Saúde. Conclui que muito há que ser feito para que a referida Agenda possa representar um pacto político internacional coerente e viável, e que os dois macroprocessos relacionados com a inovação em saúde precisam ser agilizados, mas para isto torna-se necessária a democratização da participação dos maiores interessados - os pacientes e, de modo geral, a população dos países mais pobres - pois só desta maneira será superada a "soma zero" em que se encontra o embate entre os representantes de Estados-membros nos debates atuais.

Sociodemographic and health factors associated with mortality in community-dwelling elderly.

PubMed

Borim, Flávia Silva Arbex; Francisco, Priscila Maria Stolses Bergamo; Neri, Anita Liberalesso

2017-05-04

The objective of this study is to identify factors associated with mortality, with emphasis on gender and age differences. This is a cross-sectional study, which uses data from the FIBRA-2008-2009 network in Campinas, State of São Paulo, Brazil, with information on non-institutionalized residents of the urban area and the Mortality Information System. The dependent variable has been death, in 2013. The associations have been tested by odds ratio (OR) and their 95% confidence intervals, and the analyses have been conducted using the program Stata 12.0. Average age has been 72.3 years, 69.3% have been women, and 8.9% have died. We have found greater OR for mortality in individuals aged ≥ 75 years, classified as pre-frail or frail, and in those who have reported heart disease. In this study, the analysis of specific subgroups has allowed us to better understand the relationship between the factors associated with death in the elderly. With the exception of age, strategies based on primary and secondary care, focused on priority groups, can have a positive impact on the reduction of mortality among the elderly. Identificar fatores associados à mortalidade, com ênfase nas diferenças de gênero e idade. Trata-se de estudo transversal, utilizando dados provenientes da rede FIBRA-2008-2009 em Campinas, SP, com informações de pessoas não institucionalizadas residentes na área urbana e pelo Sistema de Informações de Mortalidade. A variável dependente foi a ocorrência de óbito, verificada em 2013. As associações foram testadas pelas razões de chances (OR) e respectivos intervalos de confiança de 95%, e as análises conduzidas no programa Stata 12.0. A média de idade foi 72,3 anos, 69,3% eram mulheres e 8,9% foram a óbito. Encontrou-se maior OR para mortalidade nos indivíduos com idade ≥ 75 anos, nos classificados como pré-frágil ou frágil e naqueles que referiram doença do coração. Neste estudo, a análise para os subgrupos específicos permitiu melhor compreender a relação entre fatores que se associam ao óbito no idoso. Com exceção da idade, estratégias baseadas no cuidado específico de atenção primária e secundária, direcionadas a grupos prioritários, podem ter um impacto positivo na redução da mortalidade entre os idosos.

A causa das estações do ano: modelos mentais

NASA Astrophysics Data System (ADS)

de Campos, J. A. S.; de Araujo, J. F. S.

2003-08-01

A década de 70 do século passado foi marcada pelo estudo das concepções alternativas que os alunos trazem para a sala de aula. A identificação destas concepções foi o ponto de partida para promover a mudança conceitual, onde as pré-concepções seriam trocadas pelas concepções científicas. Na década seguinte, surgiram muitas propostas de estratégias educacionais para facilitar esta troca, na sua maioria baseadas na idéia do conflito cognitivo, proposta por Piaget. Entretanto, os resultados pouco animadores conduziram à percepção de que a mudança conceitual é um processo mais complexo. Pelas idéias da Ciência Cognitiva, a mudança conceitual é uma mudança progressiva dos modelos mentais que o aluno tem sobre o mundo físico, através de enriquecimento e revisão. A causa das Estações do Ano é um tópico sobre o qual a maioria dos estudantes apresenta concepções alternativas. Os autores fizeram um levantamento sobre as pré-concepções encontradas em trabalhos sobre o tema (16 referências), procurando encontrar elementos comuns que indicassem a presença de modelos mentais específicos. As pré-concepções encontradas na literatura foram obtidas usando-se diversas metodologias (desde entrevistas clínicas até questionários de múltipla escolha) e envolvendo alunos e professores de diferentes regiões geográficas. A partir de uma análise aprofundada de cada trabalho, e utilizando-se a técnica das Redes Sistêmicas, chegou-se a conclusão que as diversas pré-concepções identificadas (em torno de 50), poderiam ser representadas por 6 modelos mentais, onde a explicação da causa das estações do ano tem um mecanismo causal responsável. Os mecanismos causais identificados foram: a dependência da distância, a dependência da orientação, a dependência conjunta da distância e orientação, a dependência da obstrução, a dependência da velocidade e a dependência da inclinação dos raios solares. Foram ainda identificadas associações alternativas, que são um conjunto de pré-concepções, onde não existe a idéia de um modelo científico completo mas, sim, fragmentos de observação do dia a dia das pessoas.

PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENTOF DUMPING SYNDROME AND ITS RELATION TO BARIATRIC SURGERY.

PubMed

Chaves, Yasmin da Silva; Destefani, Afrânio Côgo

The dumping syndrome is frequent in bariatric surgery. It is probably the most common syndrome following partial or complete gastrectomy. Its prevalence in partial gastrectomy can reach up to 50%, thus it can be a significant complication arising from some types of bariatric surgeries. Critical analysis on dumping syndrome, its pathophysiology, diagnosis and treatment. A literature review was performed using the key words: 'dumping syndrome', 'bariatric surgery' and 'rapid dumping syndrome'. Inclusion criteria were: books, original works, case reports and meta-analyzes, and the exclusion criterion was literature review. Concerning the publication time, articles were screened between 1960 and May 2015. The dumping syndrome is complication arising from obesity surgeries, but also can be a result of vagus nerve damage. Diagnosis is done primarily through the use of questionnaires based on scores. The Sigstad score and Arts survey are valid means for assessing the dumping syndrome. Initial therapy consists in the adoption of dietary measures, short acting drugs administration. A síndrome de dumping é frequente após operações bariátricas. É, provavelmente, a mais comum das síndromes que sucedem gastrectomias parciais ou completas. Sua prevalência, em gastrectomias parciais pode chegar a até 50%, tornando-se assim complicação significante em alguns tipos de operações bariátricas. Realizar análise crítica sobre a síndrome de dumping em sua fisiopatologia, diagnóstico e tratamento. Foi realizada revisão bibliográfica utilizando os descritores: 'síndrome de dumping', 'cirurgia bariátrica' e 'síndrome do esvaziamento rápido'. Os critérios de inclusão foram: livros, trabalhos originais, relatos de caso e metanálises; excluíram-se as revisões bibliográficas. Quanto ao tempo de publicação, foram selecionados artigos entre 1960 e maio de 2015. A síndrome de dumping é complicação gastrointestinal oriunda de operações para obesidade, mas também pode ocasionar-se como consequência de danos no nervo vago. Seu diagnóstico é realizado primordialmente através da aplicação de questionários baseados em pontuações. O escore de Sigstad e questionário de Arts são meios válidos para avaliação da síndrome de dumping. A terapia inicial consiste na adoção de medidas dietéticas, ou fármacos administráveis de ação curta.

A bone tissue engineering strategy based on starch scaffolds and bone marrow cells cultured in a flow perfusion bioreactor

NASA Astrophysics Data System (ADS)

Gomes, Maria Manuela Estima

A Engenharia de Tecidos e uma area cientifica em continua expansao. Os desenvolvimentos conseguidos por esta area tem contribuido significativamente para diversos avancos no campo da Medicina Regenerativa. Esta ciencia interdisciplinar combina os conhecimentos de diversas outras areas, tao distintas como a Engenharia de Materiais e a Biologia, com o objectivo de desenvolver substitutos sinteticos para tecidos humanos. Para se atingir este objectivo utilizam-se, de uma forma generica, combinacoes especificas de celulas e de um material de suporte tridimensional com propriedades adequadas, gerando um material hibrido cujas caracteristicas podem ainda ser moduladas atraves do sistema de cultura usado. A presente tese e centrada no desenvolvimento de estrategias de engenharia de tecido osseo baseadas na cultura in vitro de celulas previamente "semeadas" num suporte tridimensional ("scaffold"). Esta estrategia permite que as celulas adiram ao suporte, proliferem e segreguem matriz extracelular especifica do tecido osseo, ate se obter um substituto artificial funcional com caracteristicas do tecido original, que pode finalmente ser transplantado para tratar o defeito em causa. Para que uma estrategia deste tipo seja bem sucedida, pelo menos tres componentes fundamentais devem ser cuidadosamente estudados: o material de suporte (scaffold), as celulas a usar e o sistema de cultura in vitro. Dai que os principais objectivos desta tese estejam relacionados com estes tres aspectos, nomeadamente: • Desenvolvimento de scaffolds biodegradaveis a partir de polimeros a base de amido de milho que induzam a adesao e proliferacao celular e que apresentem propriedades adequadas, tais como a porosidade e interconectividade entre poros, de forma a proporcionar um ambiente que favoreca o desenvolvimento in vitro de um material hibrido com caracteristicas similares ao osso humano. • Estudo da utilizacao de celulas da medula ossea como uma potencial fonte de celulas para engenharia do tecido osseo, uma vez que estas celulas podem ser facilmente recolhidas do proprio paciente a tratar por metodos nao-invasivos (bioppsia) e em quantidades suficientes. Alem disso, tratando-se de uma fonte de celulas autologas (obtidas do proprio paciente) permitem evitar os riscos de transmissao de doencas contagiosas e/ou de rejeicao pelo sistema imunologico. • Estudo da influencia das condicoes de cultura in vitro geradas por um bioreactor de perfusao (em comparacao com os metodos tradicionais de cultura em condicoes estaticas) no desenvolvimento dos materiais hibridos, compostos pelas celulas e scaffolds, assim como as interaccoes do ambiente proporcionado por este sistema de cultura com as diferentes estruturas/arquitecturas e porosidades dos scaffolds utilizados. Estes objectivos convergem para o objectivo geral desta tese que consistiu no desenvolvimento de uma terapia de engenharia do tecido osseo alternativa as existentes e com potencial para vir a ser posteriormente utilizada na pratica clinica. Este objectivo foi avaliado atraves do estudo da funcionalidade dos materiais hibridos obtidos em diferentes condicoes de cultura in vitro (e utilizando diferentes scaffolds), partindo do principio que o sistema de perfusao poderia eventualmente superar as limitacoes de difusao tipicas dos sistema de cultura estatica e simultaneamente proporcionar estimulos mecânicos as celulas, semelhantes aos encontrados em condicoes fisiologicas. (Abstract shortened by ProQuest.).

Teaching astronomy mediated by information and communication technologies: a preliminary approach

NASA Astrophysics Data System (ADS)

Rosa, R. H. L.; Voelzke, M. R.

2014-08-01

O presente trabalho é parte preliminar de um estudo mais amplo em nível de doutorado sobre o ensino de astronomia mediado pelas tecnologias da informação e comunicação, utilizando dispositivos compactos, móveis e pessoais. Este estudo também faz parte do projeto institucional do CEFETMG sobre ambientes diversificados de aprendizagem sob fomento da agência estadual FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais). Esta apresentação aborda o resultado das concepções prévias de estudantes em relação a conhecimentos básicos de astronomia, ligados à percepção e observação direta do céu. Três turmas de estudantes de 1ª série e uma turma de 3ª série do ensino integrado médio técnico da Educação Básica, Técnica e Tecnológica (EBTT) do CEFETMG Campus II - Belo Horizonte/MG foram submetidas a uma avaliação prévia através de questionário estruturado. Este questionário foi elaborado de forma a abordar a percepção dos estudantes em relação aos recursos gráficos (figuras e desenhos) representativos de conhecimentos básicos de astronomia, comuns em livros didáticos. Após a análise dos resultados desta avaliação, organizou-se uma estratégia de intervenção didática em sala de aula sobre o conteúdo de astronomia, utilizando-se de recursos de mediação baseados nas tecnologias da informação e comunicação. Os temas selecionados para esta estratégia didática foram relacionados aos assuntos básicos de astronomia em que ocorreu maior nível de desconhecimento dos estudantes. Os estudantes foram submetidos a avaliação posterior elaborada com os mesmos pressupostos da avaliação prévia. A análise dos resultados foi realizada a partir dos pressupostos da aprendizagem significativa (Ausubel; Novak e Hanesian, 1983). O ensino de astronomia por mediação das tecnologias da informação e comunicação indica uma alternativa preliminar aos trabalhos de campo usuais orientados na prática escolar, tais como, visita a planetários e a observatórios. Os estudantes ficaram muito sensibilizados pela possibilidade de percepção do céu em tempo real e à luz do dia dentro da sala de aula no contexto escolar. Os resultados deste levantamento preliminar indicam que os níveis de ensino fundamental e médio não foram capazes de internalizar conhecimentos básicos de astronomia, a despeito das orientações específicas contidas nos documentos oficiais da educação básica brasileira (Brasil, 1997 e 2000). Os estudantes pesquisados apresentaram conhecimentos e concepções rudimentares sobre o tema astronomia básica, indicando a ausência de abordagem do tema astronomia, tampouco de observação direta do céu em trabalhos de campo escolares na educação básica. Finalmente, esta abordagem didática suscitou nos estudantes grande interesse para futuros trabalhos de observação de campo. D.P. Ausubel; J.D. Novak; H. Hanesian. Psicología Educativa: un punto de vista cognoscitivo. México: Trillas, 1983. BRASIL. Secretaria de Educação Básica. Parâmetros Curriculares Nacionais: Ensino Fundamental (PCN), 1997, e Ensino Médio (PCNEM), 2000. Brasília. MEC/SEB.

Dinámica y crecimiento de los granos de polvo en la nebulosa protoplanetaria

NASA Astrophysics Data System (ADS)

de La Fuente Marcos, Carlos

2001-06-01

En el escenario estándar de la formación planetaria, los planetesimales (cuerpos de tamaño kilométrico) crecen a partir de granos de polvo, similares a los interestelares, embebidos en un disco gaseoso denominado nebulosa protoplanetaria. Durante esta etapa, los movimientos del gas pueden tener gran influencia en la dinámica y el crecimiento de los granos de polvo, dado que el flujo kepleriano del gas frena el movimiento de los mismos haciendo que caigan hacia el Sol, y la turbulencia inhibe la inestabilidad gravitacional de la capa de polvo. Aunque se acepta que los planetesimales fueron los elementos constituyentes de los planetas, todavía se desconoce cómo se produjo la formación de los mismos. Por esta razón, en los estudios más recientes, existe un renovado interés por comprender mejor la evolución de la capa de polvo inmersa en el disco gaseoso de la Nebulosa. El gas que fluye en el disco puede engendrar estructuras carentes de simetría axial, como por ejemplo ondas espirales y vórtices, a partir de gran variedad de mecanismos de excitación e inestabilidad. En 1995, Barge y Sommeria pusieron de manifiesto que la existencia de vórtices gaseosos persistentes en la nebulosa solar tendría importantes consecuencias sobre la formación de los planetesimales y el posterior crecimiento de los planetas gigantes. La investigación desarrollada en esta Tesis analiza la relación entre el polvo y el gas debida al acoplamiento por fricción dinámica entre ambos; en concreto, se estudia el efecto del flujo medio del gas sobre la dinámica de las partículas de polvo. El primer objetivo es investigar en profundidad los procesos de captura y crecimiento de los granos de polvo dentro de un vórtice y su posible relevancia en cuanto a la formación de los planetesimales. El segundo objetivo es la exploración de los efectos de ondas espirales propagándose en el disco gaseoso sobre la dinámica y el crecimiento de las partículas. La presencia de líneas de corriente no circulares perturba significativamente el movimiento de las partículas alrededor del Sol e incrementa su vida media en la Nebulosa. El flujo medio del gas se modela de forma simple, analizándose la dinámica y el crecimiento de las partículas mediante simulaciones numéricas. Al incrementarse la vida media y la densidad superficial de las partículas sólidas, los mecanismos de confinamiento derivados de la presencia de vórtices y ondas espirales actuan sobre el material sólido de la Nebulosa (mediante agregación colisional o inestabilidades gravitacionales) de manera mucho más eficiente que la previamente considerada. Esto ofrece nuevas posibilidades para la formación de planetesimales y núcleos de planetas gigantes, y puede explicar la formación rápida de planetas extrasolares gigantes. Además, esta Tesis analiza la respuesta de las partículas, en un disco protoplanetario con un radio de 100 UA en torno a una estrella de tipo solar, al campo gravitatorio derivado de la presencia de dos estrellas compañeras ligadas en una órbita relativamente elongada (300-1600 UA). Para llevar a cabo este análisis, se han realizado una serie de simulaciones numéricas de configuraciones jerárquicas coplanares utilizando un programa FORTRAN que integra directamente las ecuaciones del movimiento con el objeto de modelar la presencia de las fuerzas gravitacionales y viscosas. El disco protoplanetario masivo se encuentra en torno a una de las componentes de la binaria. La evolución temporal del subdisco de polvo depende directamente de la naturaleza (directa o retrógrada) de la revolución relativa de la compañera estelar, y de la temperatura y la masa del disco circunestelar.

Estudio numerico y experimental del proceso de soldeo MIG sobre la aleacion 6063--T5 utilizando el metodo de Taguchi

NASA Astrophysics Data System (ADS)

Meseguer Valdenebro, Jose Luis

Electric arc welding processes represent one of the most used techniques on manufacturing processes of mechanical components in modern industry. The electric arc welding processes have been adapted to current needs, becoming a flexible and versatile way to manufacture. Numerical results in the welding process are validated experimentally. The main numerical methods most commonly used today are three: finite difference method, finite element method and finite volume method. The most widely used numerical method for the modeling of welded joints is the finite element method because it is well adapted to the geometric and boundary conditions in addition to the fact that there is a variety of commercial programs which use the finite element method as a calculation basis. The content of this thesis shows an experimental study of a welded joint conducted by means of the MIG welding process of aluminum alloy 6063-T5. The numerical process is validated experimentally by applying the method of finite element through the calculation program ANSYS. The experimental results in this paper are the cooling curves, the critical cooling time t4/3, the weld bead geometry, the microhardness obtained in the welded joint, and the metal heat affected zone base, process dilution, critical areas intersected between the cooling curves and the curve TTP. The numerical results obtained in this thesis are: the thermal cycle curves, which represent both the heating to maximum temperature and subsequent cooling. The critical cooling time t4/3 and thermal efficiency of the process are calculated and the bead geometry obtained experimentally is represented. The heat affected zone is obtained by differentiating the zones that are found at different temperatures, the critical areas intersected between the cooling curves and the TTP curve. In order to conclude this doctoral thesis, an optimization has been conducted by means of the Taguchi method for welding parameters in order to obtain an improvement on mechanical properties in aluminum metal joint. Los procesos de soldadura por arco electrico representan unas de las tecnicas mas utilizadas en los procesos de fabricacion de componentes mecanicos en la industria moderna. Los procesos de soldeo por arco se han adaptado a las necesidades actuales, haciendose un modo de fabricacion flexible y versatil. Los resultados obtenidos numericamente en el proceso de soldadura son validados experimentalmente. Los principales metodos numericos mas empleados en la actualidad son tres, metodo por diferencias finitas, metodos por elementos finitos y metodo por volumenes finitos. El metodo numerico mas empleado para el modelado de uniones soldadas, es el metodo por elementos finitos, debido a que presenta una buena adaptacion a las condiciones geometricas y de contorno ademas de que existe una diversidad de programas comerciales que utilizan el metodo por elementos finitos como base de calculo. Este trabajo de investigacion presenta un estudio experimental de una union soldada mediante el proceso MIG de la aleacion de aluminio 6063-T5. El metodo numerico se valida experimentalmente aplicando el metodo de los elementos finitos con el programa de calculo ANSYS. Los resultados experimentales obtenidos son: las curvas de enfriamiento, el tiempo critico de enfriamiento t4/3, geometria del cordon, microdurezas obtenidas en la union soldada, zona afectada termicamente y metal base, dilucion del proceso, areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Los resultados numericos son: las curvas del ciclo termico, que representan tanto el calentamiento hasta alcanzar la temperatura maxima y un posterior enfriamiento. Se calculan el tiempo critico de enfriamiento t4/3, el rendimiento termico y se representa la geometria del cordon obtenida experimentalmente. La zona afectada termicamente se obtiene diferenciando las zonas que se encuentran a diferentes temperaturas, las areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Para finalizar el trabajo de investigacion se ha realizado una optimizacion, con la aplicacion del metodo de Taguchi, de los parametros de soldeo con el objetivo de obtener una mejora sustancial en las propiedades mecanicas de las uniones metalicas de aluminio.

Structural and Dynamical Aspects of Electrodeposition

DTIC Science & Technology

1993-05-01

Lfquido Utilizando Ondas Estacionarias de Rayos X " Investigaci6n y Ciencia (Scientific American in Spanish) (invited and submitted) 10. Bommarito, G. M...investigations researchers have emphasized the underpotential deposition of metal mono and multilayers employing electrochemical, x -ray based and ultra high...of adsorbate employed. 2. The underpotential deposition of copper on an iodine covered platinum surface by x -ray based techniques with emphasis on: a

Diferentes metodologias aplicadas ao ensino de astronomia no Ensino Médio

NASA Astrophysics Data System (ADS)

Albrecht, E.; Voelzke, M. R.

2009-03-01

O presente trabalho de intervenção foi realizado junto à Escola Estadual Colònia dos Pescadores na cidade de Caraguatatuba, com très turmas do terceiro ano do Ensino Médio, envolvendo 119 alunos com idades entre 16 e 19 anos. A fase inicial foi composta de um questionário de vinte questíes dissertativas e objetivas, aplicado pelo professor titular da sala, que era o mesmo nas très turmas, para diagnosticar nos educandos os conceitos prévios sobre Astronomia e, partindo destes realizar um trabalho de intervenção nas classes envolvidas utilizando, em cada uma, metodologias diferentes: (A) sob forma de seminários, elaborados e apresentados pelos educandos, no qual o educador faz apenas as intervençíes necessárias; (B) de forma tradicional, com auxílio de multimídias para desenvolvimento das aulas e a terceira (C) tradicional, fazendo uso exclusivo de lousa e giz. Ao final do trabalho os alunos responderam novamente o questionário inicial para diagnosticar dentre as très metodologias utilizadas qual apresentou melhores aplicaçíes, os resultados iniciais foram comparados com os finais. Quando questionados a respeito do significado de Astronomia observou-se inicialmente que os acertos na turma A foram de 100%, turma B: 64%, turma C: 84%, após a intervenção os acertos foram: 100%, 97% e 85% respectivamente, demonstrando que houve um avanço significativo na turma B, a turma A manteve seu índice e a turma C evoluiu, porém não tanto quanto a B. Quando interrogados sobre quantos planetas vocè acha que existem em nosso Sistema Solar? os acertos foram: turma A: 39%, turma B: 48% e turma C: 46%, após o desenvolvimento do trabalho os acertos foram 94%, 97% e 90% respectivamente. Dentro das respostas obtidas observa-se que a metodologia tradicional com o auxílio de multimeios, aplicada na turma B, demonstrou melhores resultados, sendo a mais significativa. Outra conclusão muito importante é que apesar de o tema Astronomia ser amplamente recomendado, este não é ensinado, nem no Ensino Fundamental, nem no Ensino Médio.

Evaluation of body posture in nursing students.

PubMed

Andrade, Marília Fernandes; Chaves, Érika de Cássia Lopes; Miguel, Michele Rita Oliveira; Simão, Talita Prado; Nogueira, Denismar Alves; Iunes, Denise Hollanda

2017-08-28

To investigate the body posture of nursing students before and after clinical practice. The study was developed in two stages. Initially the body posture of students of the 2nd, 4th, 6th, and 8th periods were assessed through photogrammetry. All images were analyzed in a random and masked manner with CorporisPro® 3.1.3 software. Three evaluations were performed for each angle and then the mean value was calculated. Two years later, when the 4th period students had developed their clinical internships, their body posture was again evaluated. The total sample consisted of 112 students. Comparison of their posture with the normality pattern showed that all the angles presented significant differences (p< 0.00), except for the angle of the Thales triangle. Reassessment of these students evidenced significant differences in the angles of the acromioclavicular joint (p=0.03), knee flexion (p< 0.00) and in the tibiotarsal angle (p< 0.00). All the students presented alterations when compared to the normality values. The segments that presented significant differences between before and after practice were the acromioclavicular angle, knee flexion, and tibiotarsal angle; the latter two were in the rolling position. Investigar a postura dos estudantes de enfermagem antes e após a prática clínica. O estudo foi desenvolvido em duas etapas, inicialmente com estudantes (2º, 4°, 6° e 8º períodos) tiveram sua postural corporal avaliada por meio da fotogrametria. Todas as imagens foram analisadas, de maneira aleatória e mascarada, por meio do software CorporisPro® 3.1.3. Foram realizadas três avaliações para cada ângulo e calculada a média. Dois anos depois, quando os estudantes do 4º período desenvolveram os estágios clínicos, foram novamente avaliados quanto à postura corporal. A amostra total foi composta por 112 estudantes. Comparando-se os estudantes com o padrão de normalidade, todos os ângulos apresentaram diferença significativa (p< 0,00), com exceção do ângulo triângulo de Tales. Reavaliando os mesmos estudantes, houve diferença significativa nos ângulos da articulação acromioclavicular (p=0,03), da flexão de joelhos (p< 0,00) e no ângulo tibiotársico (p< 0,00). Todos os estudantes apresentaram alterações, comparadas aos valores de normalidade. Os segmentos com diferença significativa, comparando-se antes e após a prática, foram o ângulo acromioclavicular, flexo de joelho e ângulo tibiotársico, sendo os dois últimos na posição de rolamento.

Factors associated with problematic drug use among psychiatric outpatients.

PubMed

Corradi-Webster, Clarissa Mendonça; Gherardi-Donato, Edilaine Cristina da Silva

2016-11-28

to examine the factors associated with problematic drug use among psychiatric outpatients. a cross-sectional study was carried out in two mental health services. Eligible individuals were patients of these mental health services, who used them within the data collection period. Instruments: standardized questionnaire with sociodemographic, social network, social harm, and clinical information; Alcohol, Smoking and Substance Involvement Screening Test; Barratt Impulsiveness Scale; Holmes and Rahe Stress Scale. Statistical analysis was performed using parametric statistics considering a significance level of p ≤ 0.05. Study participants were 243 patients, with 53.9% of these presenting problematic drug use. the most important independent predictors of problematic drug use were marital status (OR = 0.491), religious practice (OR = 0.449), satisfaction with financial situation (OR = 0.469), having suffered discrimination (OR = 3.821) and practicing sports activities in previous 12 months (OR = 2.25). the variables found to be predictors were those related to the social context of the patient, there, it is recommended that mental health services valorize psychosocial actions, seeking to know the social support network of patients, their modes of socialization, their financial needs, and their experiences of life and suffering. analisar os fatores associados ao consumo problemático de droga entre pacientes psiquiátricos ambulatoriais. estudo transversal em dois serviços de saúde mental. Foram considerados indivíduos elegíveis os usuários desses serviços de saúde mental, que os utilizaram dentro do período de coleta de dados. Instrumentos: Questionário padronizado sobre dados sociodemográficos, redes sociais, prejuízos sociais e informações clínicas; Teste de Triagem do Envolvimento com Álcool, Cigarro e outras Substâncias (ASSIST); Escala de Impulsividade de Barratt; e Escala de Avaliação de Reajustamento Social de Holmes e Rahe. A análise estatística foi realizada utilizando-se estatísticas paramétricas considerando um nível de significância de p ≤ 0,05. Participaram do estudo 243 pacientes, com 53,9% destes apresentando consumo problemático de drogas. os preditores independentes mais importantes do consumo problemático de drogas foram o estado civil (OR = 0,491), a prática religiosa (OR = 0,449), a satisfação com a situação financeira (OR = 0,469), ter sofrido discriminação (OR = 3,821) e a prática de atividades esportivas nos últimos 12 meses (OR = 2,25). as variáveis consideradas preditoras foram aquelas relacionadas ao contexto social do paciente, e por isso, recomenda-se que os serviços de saúde mental valorize ações psicossociais, buscando conhecer a rede de suporte social dos pacientes, seus modos de socialização, suas necessidades financeiras e suas experiências de vida e sofrimento. analizar los factores asociados al consumo problemático de droga entre pacientes siquiátricos en ambulatorios. estudio transversal en dos servicios de salud mental. Fueron considerados individuos elegibles los usuarios de esos servicios de salud mental, que utilizaron drogas dentro del período de recolección de datos. Instrumentos: cuestionario estandarizado sobre datos sociodemográficos, redes sociales, perjuicios sociales e informaciones clínicas; Test de Detección del Involucramiento con Alcohol, Cigarro y otras Sustancias (ASSIST); Escala de Impulsividad de Barratt; y Escala de Evaluación de Readecuación Social de Holmes y Rahe. El análisis estadístico fue realizada utilizando estadísticas paramétricas considerando un nivel de significación de p ≤ 0,05. Participaron del estudio 243 pacientes, con 53,9% de estos presentando consumo problemático de drogas. los predictores independientes más importantes del consumo problemático de drogas fueron: el estado civil (OR = 0,491), la práctica religiosa (OR = 0,449), la satisfacción con la situación financiera (OR = 0,469), el haber sufrido discriminación (OR = 3,821) y la práctica de actividades deportivas en los últimos 12 meses (OR = 2,25). las variables consideradas predictoras fueron aquellas relacionadas al contexto social del paciente, y por eso, se recomienda que los servicios de salud mental valoricen acciones psicosociales, buscando conocer la red de soporte social de los pacientes, sus modos de socialización, sus necesidades financieras y sus experiencias de vida y sufrimiento.

Vínculos sobre um modelo de quartessência de Chaplygin usando observações do satélite chandra da fração de massa de gás em aglomerados de galáxias

NASA Astrophysics Data System (ADS)

de Souza, R. S.

2003-08-01

Observações de Supernovas do tipo Ia mostram que a expansão do Universo está acelerando. Segundo as equações de Einstein uma componente com pressão negativa (energia escura) é necessária para explicar a aceleração cósmica. Além da energia escura é usualmente admitido que no Universo há também uma matéria exótica com pressão zero, que é chamada de matéria escura. Essa componente possui um papel fundamental na formação de estruturas no Universo. Recentemente tem se explorado a possibilidade de que matéria e energia escura poderiam ser unificadas através de uma única componente, que tem sido denominada de quartessência. Um exemplo de fluido com essas características é o Gás de Chaplygin Generalizado, que possui uma equação de estado da forma p = -A/ra. Inicialmente consideramos o caso especial a = 1 (gás de Chaplygin) e vinculamos parâmetros do modelo utilizando observações em raios-X do satélite Chandra da fração de massa de gás em aglomerados de galáxias. Uma comparação dos vínculos obtidos com esse teste com outros testes, tais como supernovas e idade do Universo, mostra que esse teste é bastante restritivo. Exibiremos ainda resultados para o caso em que a curvatura é nula e o parâmetro a está compreendido no intervalo -1 < a 1.

ALTERNATIVE TECHNIQUE FOR CHOLECYSTECTOMY COMPARABLE TO SINGLE PORT.

PubMed

Sabbag, Carlos; Blitzckow, Ana

2017-01-01

With the advancement of laparoscopic surgery, new techniques have been proposed and disseminated in order to reduce the surgical aggression and get better cosmetic results. To present alternative technique for videocholecystectomy comparable to single port technique using conventional material for laparoscopic surgery. Introduction of laparoscopic devices using two incisions; gallbladder traction with thread, exposition of Calot triangle, and ligature of cystic pedicle with polymer clips. Nine operations were carried out with this method, without complications and no increase in operative time, being compared to conventional videocholecistectomy, however vastly superior in aesthetic results. The technique is feasible, reproducible, showing benefits to patient´s safety. Com o avanço da cirurgia laparoscópica, novas técnicas têm sido propostas e difundidas com o objetivo de diminuir a agressão cirúrgica e obter melhores resultados estéticos. Apresentar técnica alternativa para videocolecistectomia similar à técnica de single port, contudo utilizando material convencional para cirurgia laparoscópica. Procedimento de videocolecistectomia com uso de duas incisões, exposição do trígono de Calot por tração da vesícula biliar com fio e ligadura dos elementos do hilo cístico com clipes de polímero. Foram realizadas nove operações com esse método, não se observando complicações e nem aumento do tempo operatório em relação à videocolecistectomia convencional, contudo com resultado estético grandemente superior. A técnica é factível, reprodutível e mostra benefícios e segurança ao paciente.

Psyche meets matter: body and personhood in the medical-scientific project of Nise da Silveira.

PubMed

Magaldi, Felipe Sales

2018-03-01

In the early 1900s, Brazilian psychiatry was marked by the use of controversial treatments, like electroconvulsive therapy, psychosurgery, and insulin coma therapy. In 1946, the Brazilian physician Nise da Silveira took the front line in criticizing these treatments by setting up a creative activities studio in the National Psychiatric Center (Centro Psiquiátrico Nacional), in Rio de Janeiro. The article examines the theoretical basis for Silveira's medical-scientific project, drawing on documental sources and fieldwork with the study group at the Museum of Images from the Unconscious (Museu de Imagens do Inconsciente), maintained by her disciples. It is argued that her thinking constituted a rejection of the assumptions of physicalism and mechanism and was closer to the ontology of vitalism and romanticism.

Systemic Arterial Hypertension in Patients Exposed to Cesium-137 in Goiânia-GO: Prevalence Study.

PubMed

Rodrigues, José Victor Rabelo; Pinto, Murillo Macêdo; Figueredo, Roberto Miller Pires; Lima, Helen de; Souto, Rafael; Sacchetim, Sylvana de Castro

2017-01-01

Systemic Arterial Hypertension (SAH) in the Brazilian population, in populations not exposed to Césio-137, presents a prevalence of 28% nationwide. However, in the group of radioactivity victims, these values are unknown. To analyze the prevalence of hypertension in patients exposed to Cesium-137 in Goiânia, enrolled in the Sistema de Monitoramento dos Radioacidentados (SISRAD) (Radioactivtity Victims Monitoring System) of the Centro de Assistência aos Radioacidentados (C.A.R.A) (Assistence Center for Radioactivity Victims). This is a descriptive, observational cross-sectional epidemiological study carried out in Goiânia-Goiás, from August 2013 to October 2014, with a group of patients enrolled in the Sistema de Monitoramento dos Radioacidentados (SISRAD) of the Centro de Assistência a Radioacidentados (C.A.R.A.). A total of 102 radioactive patients were divided into two groups: group 1 with 40 and group 2 with 62 participants. A field survey was conducted with a closed and semi-structured questionnaire in which the following contexts were addressed: sociodemographic profile, life habits and personal background. A database was created using the Google Forms application from the Google Web technologies company. The duly collected and stored data were imported and analyzed in the statistical software SPSS, version 21. The prevalence of SAH reached a total of 25% (12 individuals) of the 48 interviewees, 50% of women (24) and 50% of men (24), of which 22.9% (11) of the radioactivity victims revealed to be smokers. The prevalence of SAH in the radioactivity victims population is similar to that of the population in general. A Hipertensão Arterial Sistêmica (HAS) na população brasileira, em populações não expostas ao Césio-137, apresenta prevalência de 28% em âmbito nacional. Porém, no grupo de radioacidentados, esses valores são desconhecidos. Analisar a prevalência da HAS em pacientes expostos ao Césio-137 ocorrido em Goiânia, cadastrados no Sistema de Monitoramento dos Radioacidentados (SISRAD) do Centro de Assistência aos Radioacidentados (C.A.R.A). Estudo epidemiológico do tipo descritivo, observacional de caráter transversal realizado em Goiânia-Goiás, no período de agosto de 2013 a outubro de 2014, com grupo de pacientes cadastrados no Sistema de Monitoramento dos Radioacidentados (SISRAD) do Centro de Assistência aos Radioacidentados (C.A.R.A). Participaram da pesquisa 48 radioacidentados de um total de 102 que foram subdivididos em dois grupos: grupo 1 com 40 e o grupo 2 com 62 participantes. Realizou-se uma pesquisa de campo com questionário fechado e semi-estruturado em que foram abordados os seguintes contextos: perfil sociodemográfico, hábitos de vida e antecedentes pessoais. Criou-se um banco de dados utilizando-se o aplicativo Google Forms, da empresa de tecnologias na Web Google. Os dados devidamente coletados e armazenados foram importados e analisados no software estatístico SPSS, versão 21. Dos 48 entrevistados a prevalência de HAS atingiu um total 25% deles (12 indivíduos), sendo 50% de mulheres (24) e 50% de homens (24), dentre estes, 22,9% (11) dos radioacidentados revelaram ser tabagistas. A prevalência de HAS na população de radioacidentados se manifesta de forma semelhante ao da população em geral.

Development and validation of the Hospitality Axiological Scale for Humanization of Nursing Care.

PubMed

Galán González-Serna, José María; Ferreras-Mencia, Soledad; Arribas-Marín, Juan Manuel

2017-08-03

to develop and validate a scale to evaluate nursing attitudes in relation to hospitality for the humanization of nursing care. Participants: the sample consisted of 499 nursing professionals and undergraduate students of the final two years of the Bachelor of Science in Nursing program. the instrument has been developed and validated to evaluate the ethical values related to hospitality using a methodological approach. Subsequently, a model was developed to measure the dimensions forming the construct hospitality. the Axiological Hospitality Scale showed a high internal consistency, with Cronbach's Alpha=0.901. The validation of the measuring instrument was performed using factorial, exploratory and confirmatory analysis techniques with high goodness of fit measures. the developed instrument showed an adequate validity and a high internal consistency. Based on the consistency of its psychometric properties, it is possible to affirm that the scale provides a reliable measurement of the hospitality. It was also possible to determine the dimensions or sources that embrace it: respect, responsibility, quality and transpersonal care. desenvolver e validar uma escala que permita avaliar a atitude dos enfermeiros em termos de hospitalidade, visando a humanização da enfermagem.Participantes: a amostra foi constituída por 499 profissionais e estudantes de enfermagem dos dois últimos anos do curso de graduação em Enfermagem. utilizando-seuma abordagem metodológica, foi desenvolvido e validado um instrumento para avaliar os valores éticos relacionados com a hospitalidade. Subsequentemente, foi formulado um modelo para mediras dimensões que constituem o construto hospitalidade. a Escala Axiológica de Hospitalidade mostrou uma consistência interna elevada, com Alfa de Cronbach=0,901. A validação do instrumento de medição foi realizada usando-se métodos de análise fatorial, exploratória e confirmatória, que apresentaram bons índices de qualidade de ajuste. o instrumento desenvolvido apresentou uma validade adequada e uma consistência interna elevada. Com base na consistência de suas propriedades psicométricas, é possível afirmar que a escala proporciona uma medida confiável da hospitalidade. Também foi possível determinar as dimensões ou fontes que a compõem: o respeito, a responsabilidade, a qualidade e o cuidado transpessoal. desarrollar y validar una escala que permita evaluar la actitud enfermera ante la hospitalidad para la humanización de enfermería. Participantes: la muestra la componen 499 profesionales de enfermería y estudiantes de los dos últimos niveles académicos de la titulación de Grado en Enfermería. mediante abordaje metodológico, se ha desarrollado y validado un instrumento para evaluar valores éticos relacionados con la hospitalidad. Posteriormente, se ha formulado un modelo de medida de las dimensiones que conforman el constructo hospitalidad. la Escala Axiológica de la Hospitalidad ha mostrado una alta consistencia interna, con un Alfa de Cronbach=0.901. La validación del instrumento de medida se realizó mediante las técnicas de análisis factorial, exploratorio y confirmatorio, que presentaron unos buenos índices de bondad de ajuste. el instrumento desarrollado ha presentado una adecuada validez y una alta consistencia interna. Sus adecuadas propiedades psicométricas permiten afirmar que la escala aporta una medición fiable de la hospitalidad. También ha permitido determinar las dimensiones o fuentes que la conforman: el respeto, la responsabilidad, la calidad y el cuidado transpersonal.

Espectroscopía de Microondas en Jets Supersónicos

NASA Astrophysics Data System (ADS)

Alonso, J. L.; López, J. C.; Lesarri, A.; Blanco, S.; Sanz, M. E.; Mata, S.; Cocinero, J. E.; Sánchez, R.

Complejos con Enlace de Hidrógeno. El entorno de bajas temperaturas de una expansión supersónica es un excelente laboratorio para estudiar el comportamiento conformacional de los complejos con enlace de hidrógeno. Nuestro grupo ha observado por vez primera enlaces de hidrógeno axial y ecuatorial en los complejos de tetrahidropirano, sulfuro de pentametileno y sulfuro de trimetileno con HCl y HF [1-6] generados en las expansiones adiabáticas en He, Ne o Ar y caracterizados por espectroscopía de microondas con transformadas de Fouier. Existe controversia a la hora de considerar a las interacciones C-H\\cdotsO como enlaces de hidrógeno o como simples interacciones de van der Waals. Las interacciones C-H\\cdotsO han sido estudiadas en el dímero del dimetil eter generado en la expansión supersónica y caracterizado por espectroscopía de microondas [7]. Estas interacciones se han analizado en los complejos formados entre los alcanos sustituidos del trifluorometano y difluorometano con oxirano [8] caracterizándose la existencia de interacciones C-F\\cdotsH-C que contribuyen a la estabilización de estos complejos. Ablación Láser: Estructura de Aminoácidos. Los aminoácidos poseen puntos de fusión elevados (>200oC) y se presentan en fases condensadas como formas dipolares (+H3N-CH(R)-COO-) distintas de las neutras de las cadenas polipéptidas. Con el fin de obtener la estructura de estas formas neutras es necesario experimentar en fase gas, en un entorno libre de interacciones como el de una expansión supersónica. Para solventar el problema de su baja presión de vapor, se ha diseñado un nuevo instrumento que combina la espectroscopía de microondas en jet supersónicos con técnicas de ablación láser [9] que evita los métodos de vaporización por calentamiento que conducen a la descomposición de los aminoácidos. Diversos confórmeros de los aminoácidos naturales de la prolina [10], valina [11], cis- y trans- hidroxiprolina, serina, cisteina, ldots han sido caracterizados hasta el presente. Con este mismo dispositivo experimental de ablación láser ha sido igualmente posible generar clusters metálicos como los de Si3, Se-Te, ldots. entre otros. Moléculas generadas por descargas eléctricas. Utilizando diferentes precursores (1,1-difluoroetileno, trifluoroacetileno, acetileno, ldots) diversos fluoropoliinos [12] y fluorometilpoliinos [13] han sido por primera vez generados y caracterizados por sus espectros de rotación en la expansión adiabática de un instrumento de MBFTMW dotado de un dispositivo de descargas. Solvatación en fase gas. La formación de complejos de biomoléculas con agua en fase gas es de gran importancia para entender la naturaleza de la solvatación a escala microscópica. Los complejos indol\\cdotsH2O [14], glicina\\cdotsH2O (mediante ablación láser) azetidinona\\cdotsH2O, azetidinona\\cdots2H2O, ldots entre otros, han sido analizados en fase gas.

TENDINOPATHY AND OBESITY.

PubMed

Castro, Adham do Amaral E; Skare, Thelma Larocca; Nassif, Paulo Afonso Nunes; Sakuma, Alexandre Kaue; Barros, Wagner Haese

Tendinopathies and tendon tears account for over 30% of all musculoskeletal consultations. Obesity, which is becoming one of the world´s most prevalent public health issues, may be associated with this condition. To review the literature about tendinopathies and obesity association. This is a descriptive exploratory study using the portal Medline. Literature in English language from 2006 to 2014 were reviewed. The pathogenesis of tendinopathies includes inflammatory, regenerative and degenerative processes that happen simultaneously from early to late phases of the disease. Mechanical stress upon tendons seems to be one of the most important factors to initiate the inflammatory response, but it´s not the only one that can deflagrate it: there are other extrinsic, genetic and metabolic factors that may be involved. Therefore, tendinopathies in obese patients can be due to tendon overload because of the excess of weight, but also because of increased production of pro-inflammatory mediators related to fat tissue such as adipokines. This pro-inflammatory state that obese people can suffer is known as adiposopathy, or sick fat syndrome. Weight loss is associated with decrease in adipokines and improvement of musculoskeletal symptoms. The relation of obesity and tendinopathies is supported by evidences of recent studies, exemplified in this review of literature. As tendinopatias e as fissuras em tendões respondem por 30% de todas as consultas médicas. A obesidade, que está se tornando um dos problemas de saúde pública mais prevalentes no mundo, pode estar associada com esta condição. Revisar a literatura acerca da associação entre obesidade e tendinopatias. Este é um estudo exploratório e descritivo utilizando artigos em língua inglesa do portal médico Medline, do período de 2006 a 2014. Na patogênese das tendinopatias incluem-se elementos inflamatórios, regenerativos e degenerativos que aparecem de maneira simultânea em todos os estágios da doença. O estresse mecânico sobre os tendões parece ser um dos mais importantes na promoção do processo inflamatório inicial. Todavia não é o único. Existem fatores ambientais, genéticos e metabólicos atuando de maneira ativa. Portanto, as tendinopatias em indivíduos obesos podem se dever à sobrecarga mecânica pelo excesso de peso, mas, também, pelo aumento na produção de mediadores pró-inflamatórios relacionados ao tecido adiposo, como as adipocinas. O estado pró-inflamatório existente no indivíduo obeso é conhecido como adiposopatia ou síndrome da "gordura doente". A perda de peso está associada com decréscimo das adipocinas e diminuição da sintomatologia musculoesquelética. A associação da obesidade com tendinopatias tem sido fundamentada em estudos recentes como os desta revisão de literatura.

SLEEVE GASTRECTOMY IN PATIENTS WITH MORBID OBESITY AND HIV.

PubMed

Pinto, José Máximo Costa; Lima, Marianna Gomes Cavalcanti Leite de; Almeida, Ana Luiza Melo Cavalcanti de; Sousa, Marcelo Gonçalves

It is estimated that there are nearly 40 million people with the human immunodeficiency virus (HIV) worldwide. Due to the advent of antiretroviral drugs, it has been observed increasing in obesity and metabolic rates among patients undergoing treatment. Thus, numerous surgical therapies for weight loss are proposed for continuous improvement in health of patients with HIV, being the vertical gastrectomy an option for intact intestinal transit. To evaluate the applicability of the vertical gastrectomy in patients with morbid obesity and HIV. Was conducted a systematic review of the literature, in the electronic databases Scopus, Pubmed, Cinahl, Scielo, Cochrane and Lilacs, from 1998 to 2015. MeSH headings used in data collection were "Gastrectomy" and "Morbid obesity" being combined with the descriptor "HIV". Were found 2148 articles in Scopus, 1234 in PubMed and 784 in Cinahl. The articles were analyzed by the Jadad Quality Scale, being reduced to 40 articles, subsequently reassessed using an elaborated form by the Critical Appraisal Skills Programme (CASP), reaching 12 articles in the end. It was found that vertical gastrectomy constitutes a safe and effective method, with low mortality and low rate of postoperative complications, being recommended as surgical technique in patients with obesity, HIV and comorbidities. Estima-se que haja quase 40 milhões de pessoas com o vírus da imunodeficiência adquirida (HIV) no mundo. Com o advento dos antirretrovirais, observou-se aumento da obesidade e de taxas metabólicas nos pacientes em tratamento. Assim, inúmeras terapias cirúrgicas para a perda de peso estão sendo estudadas para a melhoria contínua da saúde dos pacientes com HIV, sendo a gastrectomia vertical uma opção de trânsito íntegro. Avaliar a aplicabilidade da gastrectomia vertical em pacientes com obesidade mórbida e HIV. Foi realizada revisão sistemática de literatura, de artigos publicados nas bases eletrônicas de dados Scopus, Pubmed, Cinahl, Scielo, Cochrane e Lilacs, no período de 1998 a 2015. Os descritores do MeSH utilizados na coleta dos dados foram "Gastrectomia" e "Obesidade mórbida", sendo combinados com o descritor "HIV". Foram encontrados 2.148 artigos na Scopus, 1.234 no Pubmed e 784 na Cinahl. Os artigos foram analisados pela Escala de Qualidade de Jadad, reduzindo para um total de 40 artigos, os quais foram posteriormente reavaliados, utilizando um formulário elaborado pelo Critical Appraisal Skills Programme (CASP), chegando ao montante de 12 artigos ao final. Verificou-se que a gastrectomia vertical constitui método seguro e eficaz, apresentando baixa morbimortalidade e baixo índice de complicações pós-operatórias, sendo técnica cirúrgica segura para uso em pacientes com obesidade, HIV e comorbidades.

Nosema ceranae Winter Control: Study of the Effectiveness of Different Fumagillin Treatments and Consequences on the Strength of Honey Bee (Hymenoptera: Apidae) Colonies.

PubMed

Mendoza, Y; Diaz-Cetti, S; Ramallo, G; Santos, E; Porrini, M; Invernizzi, C

2017-02-01

In Uruguay, colonies of honey bees moving to Eucalyptus grandis plantation in autumn habitually become infected with the microsporidian Nosema ceranae , a parasite that attacks the digestive system of bees. Beekeepers attributed to N. ceranae depopulation of the colonies that often occurs at the end of the blooming period, and many use the antibiotic fumagillin to reduce the level of infection. The aim of this study was to compare the effectiveness of four different fumagillin treatments and determine how this antibiotic affects the strength of the colonies during the winter season. The colonies treated with fumagillin in July showed less spore load at the end of applications, being the most effective the following treatments: the four applications sprayed over bees of 30 mg of fumagillin in 100 ml of sugar syrup 1:1, and four applications of 90 mg of fumagillin in 250 ml of sugar syrup 1:1 using a feeder. However, 2 month after the treatment applications, the colonies treated with fumagillin were the same size as the untreated colonies. In September, the colonies treated and not treated with fumagillin did not differ in colony strength (adult bee population and brood area) or spores abundance. Our study demonstrates that fumagillin treatment temporarily decreased the spore load of N. ceranae , but this was not reflected in either the size of the colonies or the probability of surviving the winter regardless of the dose or the administration strategy applied. Given the results obtained, we suggest to not perform the pharmacological treatment under the conditions described in the experiment. En Uruguay las colonias de abejas melíferas que se trasladan a las forestaciones de Eucalyptus grandis en otoño indefectiblemente se infectan con el microsporido Nosema ceranae , parásito que ataca el sistema digestivo de las abejas. Los apicultores atribuyen a N. ceranae el despoblamiento de las colonias que ocurre con frecuencia al terminar el periodo de floración y muchos emplean el antibiótico fumagilina para reducir el nivel de infección. El objetivo de este estudio fue comparar la eficacia de cuatro tratamientos diferentes con fumagilina y determinar cómo incide en la fortaleza de las colonias durante la invernada. Las colonias tratadas con fumagilina en julio presentaron una menor carga de esporas al terminar las aplicaciones, siendo los tratamientos más eficaces el de 4 aplicaciones mediante asperjado sobre las abejas de 30 mg de fumagilina en 100 ml de jarabe de azúcar 1:1, y el de 4 aplicaciones de 90 mg de fumagilina en 250 ml de jarabe de azúcar 1:1 utilizando un alimentador. Sin embargo, durante el período de experimentación, las colonias tratadas con antibiótico presentaron igual tamaño que las colonias no tratadas. En setiembre, las colonias tratadas y no tratadas con fumagilina no se diferenciaron en la intensidad de infección ni en su tamaño. En las condiciones en que se realizó el estudio, la aplicación de fumagilina disminuyó temporalmente la carga de esporas de N. ceranae pero esto no se reflejó en el tamaño de las colonias ni en la probabilidad de sobrevivir el invierno. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com

New tools for subsurface imaging of 3D seismic Node data in hydrocarbon exploration =

NASA Astrophysics Data System (ADS)

Benazzouz, Omar

A aquisicao de dados sismicos de reflexao multicanal 3D/4D usando Ocean Bottom NODES de 4 componentes constitui atualmente um sector de importancia crescente no mercado da aquisicao de dados reflexao sismica marinha na industria petrolifera. Este tipo de dados permite obter imagens de sub-superficie de alta qualidade, com baixos niveis de ruido, banda larga, boa iluminacao azimutal, offsets longos, elevada resolucao e aquisicao de tanto ondas P como S. A aquisicao de dados e altamente repetitiva e portanto ideal para campanhas 4D. No entanto, existem diferencas significativas na geometria de aquisicao e amostragem do campo de ondas relativamente aos metodos convencionais com streamers rebocados a superficie, pelo que e necessario desenvolver de novas ferramentas para o processamento deste tipo de dados. Esta tese investiga tres aspectos do processamento de dados de OBSs/NODES ainda nao totalmente resolvidos de forma satisfatoria: a deriva aleatoria dos relogios internos, o posicionamento de precisao dos OBSs e a implementacao de algoritmos de migracao prestack 3D em profundidade eficientes para obtencao de imagens precisas de subsuperficie. Foram desenvolvidos novos procedimentos para resolver estas situacoes, que foram aplicados a dados sinteticos e a dados reais. Foi desenvolvido um novo metodo para deteccao e correccao de deriva aleatoria dos relogios internos, usando derivadas de ordem elevada. Foi ainda desenvolvido um novo metodo de posicionamento de precisao de OBSs usando multilateracao e foram criadas ferramentas de interpolacao/extrapolacao dos modelos de velocidades 3D de forma a cobrirem a extensao total area de aquisicao. Foram implementados algoritmos robustos de filtragem para preparar o campo de velocidades para o tracado de raios e minimizar os artefactos na migracao Krichhoff pre-stack 3D em profundidade. Os resultados obtidos mostram um melhoramento significativo em todas as situacoes analisadas. Foi desenvolvido o software necessario para o efeito e criadas solucoes computacionais eficientes. As solucoes computacionais desenvolvidas foram integradas num software standard de processamento de sismica (SPW) utilizado na industria, de forma a criar, conjuntamente com as ferramentas ja existentes, um workflow de processamento integrado para dados de OBS/NODES, desde a aquisicao e controle de qualidade a producao dos volumes sismicos migrados pre-stack em profundidade.

Estudo da região HII galática NGC 2579

NASA Astrophysics Data System (ADS)

Riffel, R.; Copetti, M. V. F.

2003-08-01

Desde a descoberta dos gradientes de abundância química em galáxias espirais, as regiões HII galáticas têm sido intensamente estudadas com o objetivo de determinar a forma do gradiente de abundância química na Via-Láctea. Entretanto, a forma do gradiente galático continua controversa e existem muitas regiões HII que continuam inexploradas. A região HII galática NGC 2579 é um objeto que aparece em imagens Ha, como uma pequena mancha brilhante de aproximadamente 2 segundos de arco de diâmetro a 20 segundos de arco ao leste de RCW 20, sendo NGC 2579 muitas vezes confundida com esta última. Apesar de seu alto brilho superficial, NGC 2579 é um objeto pouco estudado provavelmente por problemas de identificação deste objeto. Como parte de um projeto de reavaliação dos gradientes de abundância química das regiões HII na Via-Láctea, estamos realizando um estudo extensivo das propriedades físicas básicas como temperatura eletrônica, densidade eletrônica e composição química da região HII galática NGC 2579. Analisamos dados espectrofotométricos de fenda longa na faixa de 3700Å a 7750Å obtidos com o telescópio de 1.52 m do ESO, Chile, em 2002. Determinamos a temperatura eletrônica usando a razão entre as linhas do [OIII] (l4959+l5007/l4363) e a densidade eletrônica pela razão entre as linhas do [SII] (l6716/l6731). As abundâncias químicas do O, N, Cl, S, Ne e He foram determinadas. Realizamos um estudo de imagens fotométricas nas bandas UBVRI obtidas em 2000 no observatório astronômico San Pedro Mártir, México, para identificar e classificar as estrelas ionizantes de NGC 2579 e determinar a distância deste objeto.

The Astronomy Club of Araranguá: Educating Science Teachers as Science Communicators. (Breton Title: Clube de Astronomia de AraranguÁ: a Formação de Professores de Ciências Como Divulgadores Científicos. ) Club de Astronomía de Araranguá: la Formación del Profesorado Como Comunicadores de la Ciencia

NASA Astrophysics Data System (ADS)

Damasio, Felipe; Allain, Olivier; Antunes Rodrigues, Adriano

2013-07-01

The study reported in this work takes place since 2009 at the Federal Institute of Education, Science and Technology of Santa Catarina, Campus Araranguá. Our main goal is to help form teachers, training undergraduate students in Natural Sciences with specialization in Physics as science communicators, as well as to promote actions of broader scientific popularization in the region of the town of Araranguá through an Astronomy Club called CA2. Among the actions of scientific popularization that the students promote are: video production, radio broadcasts, lectures, nightly observations, preparation and exhibition of posters, physics teaching for children, continuing education activities for teachers and regular physics teaching using Astronomy as a theme. The Club's teacher education and scientific dissemination work is based on the Theory of Meaningful Learning, always trying to reach the student's predisposition to learn and produce potentially meaningful material, the two essential conditions for meaningful learning to occur. O estudo que este trabalho relata ocorre desde 2009 no Instituto Federal de Educação, Ciência e Tecnologia de Santa Catarina, campus Araranguá. Nele procura-se formar divulgadores científicos durante a formação inicial de docentes do curso de Licenciatura em Ciências da Natureza com habilitação em Física, além de promover ações de divulgação científica para o público geral da região da cidade de Araranguá por meio de um Clube de Astronomia chamado CA² (Clube de Astronomia de Araranguá). Entre as ações de divulgação científica que os licenciandos promovem estão: produção de vídeos, programas de rádio, palestras, observações noturnas, confecção e exposição de pôsteres, ensino de física para crianças, formação continuada de professores em atividades e ensino de Física regular utilizando a Astronomia como tema gerador. O trabalho de formação docente e divulgação científica do Clube fundamenta-se na Teoria da Aprendizagem Significativa, sempre procurando alcançar a pré-disposição em aprender e produzir material potencialmente significativo, as duas condições necessárias para que a aprendizagem significativa ocorra. El estudio relatado en este trabajo se lleva a cabo desde 2009 en el Instituto Federal de Educação, Ciência e Tecnología de Santa Catarina, campus Araranguá. En él se busca formar a comunicadores de la ciencia durante la formación inicial de los docentes Licenciatura en Ciencias Naturales con especialidad en Física, y también promover acciones de divulgación científica para el público en general en la región de Araranguá a través de un club de astronomía llamado CA2 (Clube de Astronomia Araranguá). Entres las acciones de los estudiantes que se promueven están: producción de videos, programas de radio, conferencias, observaciones nocturnas, la preparación y exposición de carteles, la educación en física para los niños, actividades de formación permanente del profesorado y enseñanza de la física de con el tema generador Astronomía. El trabajo de la formación del profesorado y la difusión de club científico se basa en la teoría del aprendizaje significativo, buscando siempre la predisposición para aprender y producir material potencialmente significativo, las dos condiciones necesarias para que ocurra el aprendizaje significativo.

Preparation and characterization of novel nanocomposites of inorganic/polysaccharide type =

NASA Astrophysics Data System (ADS)

Oliveira, Fabiane Costa

O uso de polimeros naturais no ambito da preparacao de nanocompositos nao tem sido tao amplamente estudado quando comparado com os polimeros sinteticos. Assim, esta tese tem como objectivo estudar metodologias para a preparacao de novos materiais nanocompositos sob a forma de dispersoes e filmes utilizando polissacarideos como matriz. A tese esta dividida em cinco capitulos sendo o ultimo capitulo dedicado as conclusoes gerais e a sugestoes para trabalhos futuros. Inicialmente e apresentada uma breve revisao bibliografica sobre os principais temas colocando esta tese em contexto. Consideracoes sobre o uso de polimeros naturais e a sua combinacao com a utilizacao de nanoparticulas inorganicas para a fabricacao de novos bionanocomposites sao descritas e os objectivos e outline da tese sao tambem apresentados. No segundo capitulo, a preparacao de particulas de silica puras ou modificadas bem como a sua caracterizacao por FTIR, SEM, TEM, TGA, DLS (tamanho e potencial zeta) e medicoes de angulo de contacto sao discutidas. De modo a melhorar a compatibilidade da silica com os polissacarideos, as particulas SiO2 foram modificados com dois compostos do tipo organosilano: 3- metacril-oxipropil-trimetoxissilano (MPS) e 3-aminopropil-trimetoxissilano (APS). As particulas SiO2 MPS foram posteriormente encapsuladas com de poli(metacrilato de glicidilo) utilizando a tecnica de polimerizacao em emulsao. A utilizacao dos nanocompositos resultantes na preparacao de dispersoes de bionanocompositos nao foi bem sucedida e por esse motivo nao os estudos nao foram prosseguidos. O uso de SiO2 APS na preparacao de dispersoes bionanocomposite foi eficiente. No terceiro capitulo e apresentada uma revisao sobre dispersoes bionanocompositas e respectiva caracterizacao destacando aspectos fundamentais sobre reologia e microestrutura. Em seguida, e discutido o estudo sistematico realizado sobre o comportamento reologico de dispersoes de SiO2 utilizando tres polissacarideos distintos no que concerne a carga e as caracteristicas gelificantes: a goma de alfarroba (nao ionica), o quitosano (cationico) e a goma xantana (anionica) cujas propriedades reologicas sao amplamente conhecidas. Os estudos reologicos realizados sob diferentes condicoes demonstraram que a formacao de geis frageis e/ou bem estruturados depende do tamanho SiO2, da concentracao, do pH e da forca ionica. Estes estudos foram confirmados por analises microestruturais usando a microscopia electronica a baixas temperaturas (Cryo-SEM). No quarto capitulo, sao apresentados os estudos relativos a preparacao e caracterizacao de filmes bionanocompositos utilizando quitosano como matriz. Primeiramente e apresentada uma revisao sobre filmes de bionanocompositos e os aspectos fundamentais das tecnicas de caracterizacao utilizadas. A escolha do plasticizante e da sua concentracao sao discutidas com base nas propriedades de filmes de quitosano preparados. Em seguida, o efeito da concentracao de silica e dos metodos utilizados para a dispersar na matriz de polissacarideo, bem como o efeito da modificacao da superficie da silica e avaliado. As caracteristicas da superficie e as propriedades de barreira, mecanicas e termicas sao discutidas para cada conjunto de filmes preparados antes e apos a sua neutralizacao. Os resultados obtidos mostraram que a dispersao das cargas no plasticizante e posterior adicao a matriz polissacaridica resultaram apenas em pequenas melhorias ja que o problema da agregacao de silica nao foi ultrapassado. Por esse motivo foram preparados filmes com SiO2 APS os quais apresentaram propriedades melhores apesar da agregacao das particulas nao ter sido completamente impedida. Tal pode estar relacionado com o processo de secagem dos filmes. Finalmente, no capitulo 5, sao apresentadas as principais conclusoes obtidas e algumas sugestoes para trabalho futuro.

Difficulties of First Years Elementary School Teachers with the Teaching of Astronomy. (Breton Title: Dificuldades de Professores dos Anos Iniciais do Ensino Fundamental em Relação ao Ensino da Astronomia. ) Dificultades de LOS Profesores de los Primeros Años de la Escuela Primaria en Relación a la Enseñanza de la Astronomía

NASA Astrophysics Data System (ADS)

Langhi, Rodolfo; Nardi, Roberto

2005-12-01

This paper reports Primary School teachers' discourses analysis about their difficulties related to the teaching of Astronomy. It reports partial data of a master's level research carried out in the last two years, named "An exploratory study for inserting Astronomy in primary school teachers' education" (LANGHI, 2004). The study took into consideration students' and teachers' common sense conceptions about astronomical phenomena, conceptual mistakes in textbooks, and Astronomy's suggestions given by the PCN (Parâmetros Curriculares Nacionais - The Brazilian National Curriculum Standards). The paper aims to characterize teachers' difficulties, in order to provide subsides to the implementation of an initial or continuing education program. This study is justified by the fact that courses plans like these only will be adapted to the teacher's (and students') reality, if there is a primary investigation about what the teachers really need to know about Astronomy. This fact was possible here by the enunciations interpretation of a teachers' sample using semi-structured interviews, according to discourse analysis procedures. The research outcomes show difficulties related to factors like: those of personal order, methodological, on teacher's formation, educational infrastructure and other related to information sources for educators. Este artigo, que relata as dificuldades de professores em relação ao ensino da Astronomia, faz parte de um estudo exploratório para a inserção da Astronomia na formação de professores dos anos iniciais do Ensino Fundamental. Esse estudo leva em consideração as concepções alternativas de alunos e professores sobre fenômenos astronômicos, os erros conceituais em livros didáticos e as sugestões de conteúdos de Astronomia constantes nos PCN (Parâmetros Curriculares Nacionais). Caracterizar as dificuldades dos professores é a questão central deste texto, apontando para o objetivo de contribuir com subsídios para um futuro programa de formação continuada neste tema. O estudo se justifica mediante o fato de que planejamentos de cursos como estes só se adequarão à realidade do professor (e do aluno) se houver uma investigação antecipada sobre o que os docentes precisam saber e saber fazer a respeito da Astronomia, o que se concretizou em nosso caso pela interpretação dos discursos de uma amostra de professores coletados através de entrevistas semi-estruturadas, utilizando para interpretação os princípios e métodos da análise do discurso em sua linha francesa. Os resultados da pesquisa indicaram dificuldades de ordem pessoal, metodológica, de formação, de infra-estrutura e outras relacionadas às fontes de informações para docentes. Este artículo que relata las dificultades de los profesores en relación a la enseñanza da laAstronomía es parte de un estudio preliminar para la implantación dela Astrnomía enla formación de profesores de ls primeros años del ciclo primario.El estudio considera las concepciones alternativas de alumnos y profesores respecto a los fenómenos astronómicos, los errores conceptuales en los libros didácticos y las sugerencias de contenidos de Astronomía que constan en los Parámetros Curriculares Nacionales del Brasil. Caracterizar las dificultades de los profesores constituye la cuestión central de este texto, apuntando para el objetivo de contribuir para un futuro programa de educación contínua en este tema. El estudio se justifica mediante el hecho que la planificación de cursos de este tipo solo se adecuarán a la realidade del profesor (y del alumno) si existe una investigación anterior a respecto de lo que los docentes precisan saber y saber realizar en Astronomía, lo cual se concretó en nuestro caso por medio de la interpretación de los discursos de una muestra de profesores obtenidos através de entrevistas semiestructuradas, utilizand para esta interpretación los principios y métodos de análisis del discurso en su línea francesa. Los resultados mostraron dificultades de orden personal, metodológica, formativa, de infraestructura y otras relacionadas a las fuentes de información para los docentes.

Un Marco Abierto: Un Manual de Matematicas y Ciencas Utilizando Inteligencias Multiples Disenado para Estudiantes Bilingues de Educacion General y Especial (An Open Framework: A Math and Science Manual Utilizing Multiple Intelligences Designed for Bilingual Students in General and Special Education).

ERIC Educational Resources Information Center

New York City Board of Education, Brooklyn, NY. Office of Bilingual Education.

This manual incorporates a Multiple Intelligences perspective into its presentation of themes and lesson ideas for Spanish-English bilingual elementary school students in grades 4-8 and is designed for both gifted and special education uses. Each unit includes practice activities, semantic maps to illustrate and help organize ideas as well as…

Revista de Saúde Pública in scientific publications on Violence and Health (1967-2015).

PubMed

Schraiber, Lilia Blima; Barros, Claudia; d'Oliveira, Ana Flávia Pires Lucas; Peres, Maria Fernanda Tourinho

2016-11-10

This article retrieved the publications from the Revista de Saúde Pública journal (from 1967 to 2015) on violence and health, on the SciELO and PubMed bases, by searching for the terms "violence", "suicide", "aggression", "bullying", and "external causes", registered in any part of the text. We found 130 articles (the first one published in 1974). We observed: increase of publications over time, with decrease in the last five years; similar production volume in lethal and non-lethal violence; later publication of the latter; few studies in qualitative research; mostly descriptive production; and visualization of the problem more by the acts than by contexts or motivations and aggressors. Social markers were little approached, appearing, from largest to smallest frequency, social class, gender, race/ethnicity, and generation. Human rights were little used and only recently used as analytical framework, connected more to gender than to social class. Although Revista de Saúde Pública has registered the theme in its publications, consolidating it as scientific production line, there is still great explanatory theoretical rarefaction and little intersectionality between violence, social inequalities, and human rights. RESUMO A produção da Revista de Saúde Pública (de 1967 até 2015) sobre violência e saúde foi recuperada nas bases SciELO e PubMed utilizando-se os termos "violência", "suicídio", "agressões", "bullying" e "causas externas", registrados em qualquer parte do texto. Foram encontrados 130 artigos (o primeiro deles publicado em 1974). Constatou-se: aumento das publicações no tempo, com decréscimo nos últimos cinco anos; volume similar de produção em violência letal e não letal; publicação mais tardia desta última; poucos estudos em pesquisa qualitativa; produção majoritariamente descritiva; e visibilização do problema, mais pelos atos que pelos contextos ou motivações e agressores. Os marcadores sociais foram pouco tematizados, aparecendo da maior para a menor frequência, classe social, gênero, raça/etnia e geração. Direitos humanos foi pouco, e apenas recentemente, usado como referencial analítico, conectado mais ao gênero do que à classe social. Embora a Revista de Saúde Pública tenha inscrito o tema em suas publicações, consolidando-o como linha de produção científica, há, ainda, grande rarefação teórica explicativa e pouca interseccionalidade entre violência, desigualdades sociais e direitos humanos.

Analysis of Service-learning activities adopted in health courses of Federal University of Bahia.

PubMed

Baldoino, Aline Silva; Veras, Renata Meira

2016-06-01

is study aimed to raise and discuss the data about the integration of health courses teaching and service activities o ered at the Federal University of Bahia (UFBA), pre- senting scenarios practices and major di culties existing in the relationship between the university and the services of health. is was a qualitative study of descriptive explo- ratory character, using a questionnaire as a research tool applied to the coordinators of selected health courses. e selection was by reading the political pedagogical project, the following courses were selected: nursing, physical therapy, speech therapy, medicine, nu- trition, dentistry and public health. e results indicated eight types of teaching-service integration activities, 57 scenarios of practice and the main di culties. It was concluded that these courses are sticking to changes in academic training in health, in view of the large number of basic health units in the teaching service process. us, it emphasizes that the UFBA includes activities in health care that enable the integration-education in the higher education process, although there are some di culties in this relationship indicated by the coordinators. Esse estudo teve como objetivo levantar e discutir os dados acerca das atividades de integração ensino-serviço de cursos de saúde oferecidos na Universidade Federal da Bahia (UFBA), apresentando os cenários de práticas e as principais di culdades existentes na relação entre a uni- versidadeeosserviçosdesaúde.Tratou-sedeumapesquisaqualitativa,decaráterdescritivoexploratório,utilizando-seumquestionáriocomo instrumento de investigação aplicado aos coordenadores dos cursos de saúde selecionados. A seleção foi mediante a leitura do projeto político pedagógico, sendo selecionados os seguintes cursos: enfermagem, sioterapia, fonoaudiologia, medicina, nutrição, odontologia e saúde coletiva. Os resultados indicaram 8 tipos de atividades de integração ensino-serviço, 57 cenários de prática e as principais di culdades. Concluiu-se que esses cursos estão aderindo às mudanças na formação acadêmica em saúde, tendo em vista o grande número de unidades básicas de saúde que integram o processo de ensino serviço. Dessa forma, ressalta-se que a UFBA contempla atividades na área de saúde que viabilizam a integração-ensino no processo de formação superior, embora existam algumas di culdades nesta relação apontadas pelos coordenadores.

Phytoreovirus-like sequences isolated from salivary glands of the glassy-winged sharpshooter Homolodisca vitripennis (Hemiptera: Cicadellidae)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsar, C.S.; Hunter, W.B.; Sinisterra, X.H.

The salivary glands of the Glassy-winged sharpshooter (GWSS), Homalodisca vitripennis Germar 1821, (syn. H. coagulata, Hemiptera: Cicadellidae) were collected and used to produce a cDNA library. Examination by BLASTX analyses identified 2 viral sequences, one a 610-base pair fragment and a second 839-base pair fragment, both of which had significant homology to viruses within the genus Phytoreovirus. Resequencing of the fragments confirmed sequence validities. These sequences were used for in silico protein translation and BLASTP analysis confirming the established homology. While the GWSS is the primary vector of Pierce's disease of grapes, this is the first report that GWSS maymore » be a vector of a phytoreoviruses. Phylogenetic and homology comparisons with BLASTX, BLASTP, and PAUP analyses indicated that the viral sequences isolated from GWSS were closely related to the viruses in the Family Reoviridae, Genus Phytoreovirus, specifically Rice Dwarf Phytoreovirus (RDV). RDV is the only plant reovirus that is not limited to the phloem. Phytoreoviruses are transmitted in a propagative manner by cicadellid leafhoppers (Hemiptera: Cicadellidae), which acquire and transmit them during feeding. Phytoreoviruses have been reported from Agallian, Agalliopsis, Nephotettix, and Recilia, genera of leafhoppers, with evidence for transovarial transmission. The GWSS, although considered to feed primarily from the xylem, ingests from other plant tissues, such as the phloem and mesophyll during probing similar to other leafhoppers. The feeding behavior and wide host range of the GWSS provides an overlapping condition for these two organisms, leafhopper and virus. GWSS will feed from grasses as a transitory host, and on herbaceous and woody plants as primary hosts, which may favor the acquisition and transmission of Phytoreovirus by this leafhopper. Monitoring for an increase of Phytoreovirus spread in graminaceous crops that are in proximity to vineyards or tree crop orchards, where GWSS occurs, such as in southern California, will provide a better understanding of the potential role of the GWSS as a disease vector in the spread of phytoreoviruses and other plant pathogens. The sequences have been deposited in NCBI database under the accession numbers (EF058280) for GWSS-V1, WHSg013C11 and (EF058281) for GWSS-V2, WHSg024H02. (author) [Spanish] Dos fragmentos de 610 y 839 pares de bases fueron aislados apartir de una genoteca de expresion derivada de las glandulas salivales del cucarron de las alas cristalinas (GWSS), Homalodisca vitripennis, Germar 1821 (syn. H. coagulata) el cual es vector de la enfermedad de Pierce de las uvas. Los resultados de alineamiento utilizando BLASTX, BLASTP y el analisis filogenetico utilizando PAUP indicaron que los fragmentos de DNA estaban relacionado de manera mas cercana a viruses en la familia Reoviridae, genero Phytoreovirus, y especificamente a los virus del enanismo del arroz (RDV) y al virus del tumor de las grietas (WTV). El cucarron de las alas cristalinas es un saltahoja que se alimenta no solo del xilema sino tambien del floema y del mesofilo. Saltahojas del genero Agallian, son los principales vectores de WTV, el cual infecta el floema de plantas dicotiledoneas tumoraciones en las hojas y en las raices. WTV es transmitido por saltahojas y es el unico reovirus que es capaz de infectar tanto tejidos del xilema como del floema. El comportamiento alimentario del GWSS y su amplio rango de hospederos que incluye pastos y plantas herbaceas y lenosas podria proveer la interaccion entre estos dos organismos facilitando la adquisicion y tranmision de fitoreovirus por el GWSS. Un adecuado monitoreo de el incremento en la expansion de reoviruses en cultivos de gramineas asociados al los vinedos en donde GWSS ocurre en regiones tales como el sur de California, y en general el sur de los Estados Unidos, podria proveer un mejor entendimiento del papel del GWSS como vector de fitoreovirus y otros patogenos de plantas. Las sequencias se depositaron en la base de datos NCBI con los siguientes numeros de identificacion: (EF058280) para GWSS-V1, WHSg013C11 y (EF058281) para GWSSV2, WHSg024H02. (author)« less

Exploration of priority actions for strengthening the role of nurses in achieving universal health coverage.

PubMed

Maaitah, Rowaida Al; AbuAlRub, Raeda Fawzi

2017-01-30

to explore priority actions for strengthening the role of Advanced Practice Nurses (APNs) towards the achievement of Universal Health Converge (UHC) as perceived by health key informants in Jordan. an exploratory qualitative design, using a semi-structured survey, was utilized. A purposive sample of seventeen key informants from various nursing and health care sectors was recruited for the purpose of the study. Content analysis utilizing the five-stage framework approach was used for data analysis. the findings revealed that policy and regulation, nursing education, research, and workforce were identified as the main elements that influence the role of APNs in contributing to the achievement of UHC. Priority actions were identified by the participants for the main four elements. study findings confirm the need to strengthen the role of APNs to achieve UHC through a major transformation in nursing education, practice, research, leadership, and regulatory system. Nurses should unite to come up with solid nursing competencies related to APNs, PHC, UHC, leadership and policy making to strengthen their position as main actors in influencing the health care system and evidence creation. analisar as ações prioritárias para o fortalecimento do papel da enfermeira em prática avançada na Cobertura Universal de Saúde , segundo a percepção dos informantes-chave na Jordânia. foi utilizado desenho qualitativo exploratório, com um questionário semiestruturado. A amostra intencional de dezessete informantes-chave de vários setores de enfermagem e de saúde foi recrutado para o propósito do estudo. A análise de conteúdo utilizando a abordagem do quadro de cinco estágios foi utilizada para a análise de dados. os resultados revelaram que as políticas e regulações, educação em enfermagem, pesquisa e força de trabalho foram identificados como os principais elementos que influenciam o papel da enfermeira em prática avançada em contribuir para a realização da Cobertura Universal de Saúde. As ações prioritárias foram identificadas pelos participantes para os quatro principais elementos. os resultados do estudo confirmam a necessidade de reforçar o papel da enfermeira em prática avançada para alcançar Cobertura Universal de Saúde através de uma grande transformação no ensino de enfermagem, prática, pesquisa, liderança e sistema regulatório. A Enfermagem deve unir-se para obter competências consistentes relacionadas com a enfermeira em prática avançada, atenção primaria de saúde, Cobertura Universal em Saúde, liderança e elaboração de políticas para reforçar sua posição como atores principais que influenciam o sistema de saúde e a geração de evidências. explorar las acciones prioritarias para el fortalecimiento del papel de las enfermeras con práctica avanzada para el logro de la Cobertura Universal de Salud según la percepción de informantes clave de la salud en Jordania. se utilizó diseño cualitativo exploratorio, utilizando una encuesta semi-estructurada. Una muestra intencional de diecisiete informantes clave de diversos sectores de enfermería y cuidados de la salud fue reclutada para el propósito de este estudio. Se utilizó análisis de contenido usando el método del marco de cinco etapas para el análisis de datos. los resultados revelaron que la política y la regulación, la formación de enfermería, la investigación y la fuerza laboral fueron identificados como los principales elementos que influyen en el papel de la enfermeras con práctica avanzada para contribuir a la consecución de la Cobertura Universal de Salud. Las acciones prioritarias fueron identificadas por los participantes para los cuatro elementos principales. los hallazgos del estudio confirman la necesidad de fortalecer el papel de la enfermeras con práctica avanzada para lograr la Cobertura Universal de Salud a través de una transformación importante en la formación, la práctica, la investigación, el liderazgo, y el sistema de regulación. Las enfermeras deben unirse para alcanzar competencias consistentes de enfermería relacionados con la enfermeras con práctica avanzada, la Atención Primaria de Salud , Cobertura Universal de Salud, liderazgo y formulación de políticas, para fortalecer su posición como actores principales que influyen en el sistema de salud y la generación de evidencias.

Infusion pumps and red blood cell damage in transfusion therapy: an integrative revision of the academic literature.

PubMed

Wilson, Ana Maria Miranda Martins; Peterlini, Maria Angélica Sorgini; Pedreira, Mavilde da Luz Gonçalves

2016-08-15

to obtain information from scientific literature concerning infusion pumps used in administering erythrocyte (red blood cells) and to evaluate the implications in the practical use of this equipment by nurses when conducting transfusions. an integrative revision of the following scientific databases: Pubmed/Medline, Scopus, the Virtual Library for Health, SciELO, Web of Science and Cochrane. The following descriptors were used: "infusion pumps", "blood transfusion", "transfused erythrocyte" and "hemolyis". There were no restrictions on the scope of the initial data and it was finalized in December 2014. 17 articles were identified in accordance with the inclusion and exclusion criteria. all of the publications included in the studies were experimental in vitro and covered the use of infusion pumps in transfusion therapy. A summary of the data was presented in a synoptic chart and an analysis of it generated the following categories: cellular damage and the infusion mechanism. infusion pumps can be harmful to erythrocytes based on the infusion mechanism that is used, as the linear peristaltic pump is more likely to cause hemolysis. Cellular damage is related to the plasmatic liberation of markers that largely dominate free hemoglobin and potassium. We reiterate the need for further research and technological investments to guide the development of protocols that promote safe practices and that can contribute to future clinical studies. identificar na literatura a produção científica acerca dos efeitos de bomba de infusão na administração de hemácias e avaliar as implicações do uso desses equipamentos na prática transfusional de enfermagem. revisão integrativa de literatura nas bases de dados Pubmed/Medline, Scopus, Biblioteca Virtual em Saúde, SciELO, Web of Science e Cochrane, utilizando os descritores "bombas de infusão", "transfusão de sangue", "transfusão de eritrócitos" e "hemólise". A data inicial não foi delimitada e a final foi dezembro de 2014. Foram identificados 17 artigos de acordo com os critérios de inclusão e exclusão. Todas as publicações incluídas eram estudos experimentais in vitro e abordavam o uso de bombas de infusão na terapêutica transfusional. A síntese dos dados foi apresentada em quadro sinóptico e a análise gerou duas categorias relevantes: lesão celular e mecanismo de infusão. bombas de infusão podem ser deletérias às hemácias de acordo o mecanismo de infusão, sendo que as peristálticas lineares foram mais predisponentes à hemólise. A lesão celular foi relacionada à liberação plasmática de marcadores, predominando a hemoglobina livre e potássio. Reitera-se a necessidade de pesquisas adicionais e investimentos tecnológicos para nortear o desenvolvimento de protocolos que promovam prática segura e que subsidiem futuros estudos clínicos. identificar en la literatura la producción científica acerca de los efectos de la bomba de transfusión en la administración de glóbulos rojos y evaluar las implicaciones del uso de esos equipos en la práctica transfusional de enfermería. revisión integradora de literatura en las bases de datos Pubmed/Medline, Scopus, Biblioteca Virtual en Salud, SciELO, Web of Science y Cochrane, utilizando los descriptores "bombas de infusión", "transfusión de sangre", "transfusión de eritrocitos" y "hemolisis". La fecha inicial no fue delimitada y la final fue en diciembre de 2014. Fueron identificados 17 artículos de acuerdo con los criterios de inclusión y exclusión. todas las publicaciones incluidas eran estudios experimentales in vitro y abordaban el uso de bombas de infusión en la terapéutica transfusional. La síntesis de los datos se presenta en un cuadro sinóptico y el análisis generó dos categorías relevantes: lesión celular y mecanismo de transfusión. las bombas de infusión pueden ser perjudiciales para los glóbulos rojos de acuerdo el mecanismo de transfusión, siendo que las peristálticas lineares fueron más predisponentes para la hemolisis. La lesión celular fue relacionada a la liberación plasmática de marcadores, predominando la hemoglobina libre y el potasio. Se reitera la necesidad de realizar investigaciones adicionales e inversiones tecnológicas que puedan orientar el desarrollo de protocolos que promuevan la práctica segura y que ayuden a futuros estudios clínicos.

Radium-223 in the treatment of bone metastasis in patients with castration-resistant prostate cancer. Review and procedure.

PubMed

Orcajo-Rincon, J; Caresia-Aróztegui, A P; Del Puig Cózar-Santiago, M; García-Garzón, J R; de Arcocha-Torres, M; Delgado-Bolton, R C; García-Velloso, M J; Alvarez-Ruiz, S; García-Vicente, A M

2018-04-13

Bone metastatic disease is the main cause of morbidity / mortality in patients with prostate cancer, presenting frequently as bone pain, pathological fractures or spinal cord compression, which requires early and timely therapy. Although, for the moment, the therapeutic window for its use has not been definitively established, radium-223 ( 223 Ra), an alpha particle emitter, has proved to be an effective therapeutic tool, pre or post-chemotherapy, in patients with castration-resistant prostate cancer with symptomatic bone metastases and absence of visceral metastases, significantly modifying the prognosis of the disease. It is therefore imperative to define the ideal scenarios and the correct protocol for the use of this therapy and thus offer the greatest possible clinical benefit to the patient. Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.

Clinical simulation with dramatization: gains perceived by students and health professionals.

PubMed

Negri, Elaine Cristina; Mazzo, Alessandra; Martins, José Carlos Amado; Pereira, Gerson Alves; Almeida, Rodrigo Guimarães Dos Santos; Pedersoli, César Eduardo

2017-08-03

to identify in the literature the gains health students and professionals perceive when using clinical simulation with dramatization resources. integrative literature review, using the method proposed by the Joanna Briggs Institute (JBI). A search was undertaken in the following databases: Latin American and Caribbean Health Sciences Literature, Web of Science, National Library of Medicine, Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library, Scopus, Scientific Electronic Library Online. 53 studies were analyzed, which complied with the established inclusion criteria. Among the different gains obtained, satisfaction, self-confidence, knowledge, empathy, realism, reduced level of anxiety, comfort, communication, motivation, capacity for reflection and critical thinking and teamwork stand out. the evidence demonstrates the great possibilities to use dramatization in the context of clinical simulation, with gains in the different health areas, as well as interprofessional gains. identificar na literatura quais os ganhos percebidos pelos estudantes e profissionais da área de saúde, utilizando-se da simulação clínica realizada com recursos da dramatização. revisão integrativa da literatura, com a metodologia proposta pelo Instituto Joanna Briggs (JBI), com busca nas bases de dados: Literatura Latino-Americana e do Caribe em Ciências da Saúde, Web of Science, National Library of Medicine, Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library, Scopus, Scientific Electronic Library Online. foram analisados 53 estudos, que atenderam os critérios de inclusão estabelecidos. Entre os diversos ganhos obtidos, destaca-se a satisfação, autoconfiança, conhecimento, empatia, realismo, diminuição do nível de ansiedade, conforto, comunicação, motivação, capacidade de reflexão e de pensamento crítico e trabalho em equipe. as evidências demonstram a ampla possibilidade de uso da dramatização no contexto de simulação clínica com ganhos nas diversas áreas de saúde e, também, interprofissionais. identificar en la literatura cuales los beneficios por los estudiantes y profesionales del área de salud, usándose la simulación clínica con recursos de dramatización. revisión integradora de la literatura, aplicándose la metodología propuesta por el Instituto Joanna Briggs (JBI), con búsqueda en las bases de datos: Literatura Latinoamericana y del Caribe en Ciencias de la Salud, Web of Science, National Library of Medicine, Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library, Scopus, Scientific Electronic Library Online. fueron analizados 53 estudios, que cumplieron con los criterios de inclusión establecidos. Entre los diversos beneficios obtenidos, se destacan la satisfacción, autoconfianza, conocimiento, empatía, realismo, disminución del nivel de ansiedad, conforto, comunicación, motivación, capacidad de reflexión y de pensamiento crítico y trabajo en equipo. las evidencias demuestran la amplia posibilidad de uso de la dramatización en el contexto de simulación clínica con beneficios en las diversas áreas de salud, y también interprofesionales.

Weathering resistance of thin plasma polymer films on pre-coated steel =

NASA Astrophysics Data System (ADS)

Serra, Ricardo Gil Henriques

O trabalho apresentado teve origem no projecto de investigacao “Tailored Thin Plasma Polymers Films for Surface Engineering of Coil Coated Steel”, financiado pelo Programa Europeu ECSC Steel Research. Sistemas de aco galvanizado pre-pintado em banda a base de poliester e poliuretano foram submetidos a um processo de polimerizacao por plasma onde um filme fino foi depositado de modo a modificar as propriedades de superficie. Foram usados reactores de catodo oco, microondas e radio frequencia para a deposicao do polimero fino. Os sistemas preparados foram analisados de modo a verificar a influencia do processo de polimerizacao por plasma na alteracao das propriedades barreira dos sistemas pre-pintados em banda. Foi estudado o efeito dos diferentes passos do processo de polimerizacao por plasma, bem como o efeito de diferentes variaveis operatorias. A mistura precursora foi variada de modo a modificar as propriedades da superficie de modo a poder vir a obter maior hidrofobicidade, maior resistencia a marcas digitais, bem como maior facilidade de limpeza. Os testes foram conduzidos em solucao de NaCl 0,5 M. Para o trabalho foram usadas tecnicas de analise da morfologia da superficie como Microscopia de Forca Atomica e Microscopia Electronica de Varrimento. As propriedades electroquimicas dos sistemas foram estudadas por Espectroscopia de Impedancia Electroquimica. A estrutura dos filmes gerados no processo de polimerizacao por plasma foi caracterizada por Microscopia de Transmissao Electronica. A modificacao das propriedades opticas devido ao processo de polimerizacao por plasma foi tambem obtida.

Acceptability of an Embodied Conversational Agent-based Computer Application for Hispanic Women

PubMed Central

Wells, Kristen J.; Vázquez-Otero, Coralia; Bredice, Marissa; Meade, Cathy D.; Chaet, Alexis; Rivera, Maria I.; Arroyo, Gloria; Proctor, Sara K.; Barnes, Laura E.

2015-01-01

There are few Spanish language interactive, technology-driven health education programs. Objectives of this feasibility study were to: 1) learn more about computer and technology usage among Hispanic women living in a rural community; and 2) evaluate acceptability of the concept of using an embodied conversational agent (ECA) computer application among this population. A survey about computer usage history and interest in computers was administered to a convenience sample of 26 women. A sample video prototype of a hospital discharge ECA was administered followed by questions to gauge opinion about the ECA. Data indicate women exhibited both a high level of computer experience and enthusiasm for the ECA. Feedback from community is essential to ensure equity in state of the art dissemination of health information. Hay algunos programas interactivos en español que usan la tecnología para educar sobre la salud. Los objetivos de este estudio fueron: 1) aprender más sobre el uso de computadoras y tecnología entre mujeres Hispanas que viven en comunidades rurales y 2) evaluar la aceptabilidad del concepto de usar un programa de computadora utilizando un agente de conversación encarnado (ECA) en esta población. Se administro una encuesta sobre el historial de uso y del interés de aprender sobre computadoras fue a 26 mujeres por muestreo de conveniencia. Un ejemplo del prototipo ECA en forma de video de un alta hospitalaria fue administrado y fue seguido por preguntas sobre la opinión que tenían del ECA. Los datos indican que las mujeres mostraron un alto nivel de experiencia con las computadoras y un alto nivel de entusiasmo sobre el ECA. La retroalimentación de la comunidad es esencial para asegurar equidad en la diseminación de información sobre la salud con tecnología de punta. PMID:26671558

Factors associated with the incidence of pressure ulcer during hospital stay.

PubMed

Matozinhos, Fernanda Penido; Velasquez-Melendez, Gustavo; Tiensoli, Sabrina Daros; Moreira, Alexandra Dias; Gomes, Flávia Sampaio Latini

2017-05-25

Estimating the incidence rate of pressure ulcers and verifying factors associated with this occurrence in a cohort of hospitalized patients. This is a cohort study in which the considered outcome was the time until pressure ulcer occurrence. Estimated effect of the variables on the cumulative incidence ratio of the outcome was performed using the Cox proportional hazards model. Variable selection occurred via the Logrank hypothesis test. The sample consisted of 442 adults, with 25 incidents of pressure ulcers. Patients with high scores on the Braden scale presented a higher risk of pressure ulcer incidence when compared to those classified into the low score category. These results reinforce the importance of using the Braden Scale to assist in identifying patients more likely to develop pressure ulcers. Estimar a taxa de incidência de úlcera por pressão e verificar fatores associados a essa ocorrência em uma coorte de pacientes hospitalizados. Trata-se de estudo de coorte no qual o desfecho foi a ocorrência da úlcera por pressão. A estimativa do efeito das variáveis para a proporção de incidência acumulada do desfecho foi realizada utilizando o modelo de riscos proporcionais de Cox. A seleção das variáveis ocorreu por meio do teste de hipóteses Logrank. A amostra foi composta de 442 adultos, com 25 casos incidentes de úlcera por pressão. Pacientes com altos escores na escala de Braden apresentaram maior risco de incidência de úlcera por pressão quando comparados com aqueles classificados na categoria de baixo escore. Os resultados reforçam a importância do uso da Escala de Braden para auxiliar na identificação dos pacientes com maior probabilidade de desenvolver úlcera por pressão.

HOW TO EVALUATE SCIENTIFIC PRODUCTION.

PubMed

Antunes, Alberto Azoubel

2015-01-01

To conduct a critical analysis of the two main bibliometric indexes used by science: the impact factor and the H index. Research was conducted on PubMed using the keywords: impact factor, Bibliometrics and H index. The citations of articles tend to follow a curve in which the articles published in a given year increase sharply to a peak occurring between two and six years after its publication. From this peak citations decline over time. The analysis of the scientific merit should not be based on only in bibliometric measure, but in the association of various parameters. The impact factor and the H index is mainly based on the number of citations of scientific papers, and this parameter, although important, should not be used alone, nor overvalued in the evaluation of teaching merit. Realizar análise crítica dos dois principais índices bibliométricos utilizados pela ciência: o fator de impacto e o índice H. Foi realizada pesquisa no Pubmed utilizando as palavras-chave: impact factor, bibliometrics, H index. As citações dos artigos tendem a seguir uma curva em que os artigos publicados em determinado ano aumentam agudamente para um pico que ocorre entre dois e seis anos após sua publicação. A partir deste pico, as citações declinam ao longo do tempo. A análise do mérito científico não deve ser baseada em apenas uma medida bibliométrica, mas em associação de medidas. O FI e o índice H se baseiam fundamentalmente no número de citações dos artigos científicos, e este parâmetro, apesar de importante, não deve ser utilizado sozinho e tampouco supervalorizado na avaliação do mérito docente.

Nursing team's conceptions about the families of hospitalized children.

PubMed

Macedo, Isabela Fornerolli de; Souza, Tania Vignuda de; Oliveira, Isabel Cristina Dos Santos; Cibreiros, Sylvia Alves; Morais, Rita de Cássia Melão de; Vieira, Rosana Fidelis Coelho

2017-01-01

to describe nursing team care and discuss the nursing team's conception of companion families of hospitalized children. The study was based on the theoretical framework of Collière's theory of nursing care identity. this was a qualitative study with 14 members of a nursing team, conducted through an unstructured group interview. Thematic data analysis was employed. habitual and repair care was delegated to families, regardless of the child's clinical condition. the team's official discourse about the families of hospitalized children, as recommended by the literature, refers to the family's alterity and participation in care provision, with sights on discharge and defending family participation as beneficial to children. In practice, however, the nursing staff makes concessions about the presence of chaperoning families and delegates care. descrever os cuidados da equipe de enfermagem e discutir as concepções da equipe de enfermagem frente à família acompanhante da criança hospitalizada. O referencial teórico está vinculado à identidade do cuidado de enfermagem de Collière. Estudo qualitativo com quatorze membros da equipe de enfermagem, utilizando a técnica de entrevista não diretiva em grupo. Foi realizada análise temática dos dados. os cuidados habituais e de reparação prestados à criança estão sendo delegados à família, independentemente da situação clínica da criança. o discurso oficial da equipe de enfermagem frente à família acompanhante da criança hospitalizada, preconizado pela literatura, refere-se à alteridade e à participação da família nos cuidados à criança, prevendo sua alta e justificando a participação como benéfica para a criança. Em contrapartida, na prática, a enfermagem faz concessões sobre a permanência da família e delega os cuidados.

Methodological proposal for validation of the disinfecting efficacy of an automated flexible endoscope reprocessor.

PubMed

Graziano, Kazuko Uchikawa; Pereira, Marta Elisa Auler; Koda, Elaine

2016-08-08

to elaborate and apply a method to assess the efficacy of automated flexible endoscope reprocessors at a time when there is not an official method or trained laboratories to comply with the requirements described in specific standards for this type of health product in Brazil. the present methodological study was developed based on the following theoretical references: International Organization for Standardization (ISO) standard ISO 15883-4/2008 and Brazilian Health Surveillance Agency (Agência Nacional de Vigilância Sanitária - ANVISA) Collegiate Board Resolution (Resolução de Diretoria Colegiada - RDC) no. 35/2010 and 15/2012. The proposed method was applied to a commercially available device using a high-level 0.2% peracetic acid-based disinfectant. the proposed method of assessment was found to be robust when the recommendations made in the relevant legislation were incorporated with some adjustments to ensure their feasibility. Application of the proposed method provided evidence of the efficacy of the tested equipment for the high-level disinfection of endoscopes. the proposed method may serve as a reference for the assessment of flexible endoscope reprocessors, thereby providing solid ground for the purchase of this category of health products. propor e aplicar um método para a avaliação da eficácia de processadoras automáticas de endoscópios flexíveis, em um momento em que ainda não existe no Brasil um método oficial, nem tampouco laboratórios capacitados que contemplem os requisitos das normas específicas aplicáveis a esse tipo de produto para a saúde. caracterizou-se como pesquisa metodológica e foi desenvolvido com base em três referenciais teóricos: norma técnica International Organization for Standardization (ISO) - ISO 15883-4/2008, Resolução de Diretoria Colegiada (RDC) nº35/2010 e RDC nº15/2012 da Agência Nacional de Vigilância Sanitária (ANVISA). Aplicou-se o método proposto em um equipamento específico, comercialmente disponível, utilizando desinfetante de alto nível à base de ácido peracético 0,2%. o método de avaliação proposto mostrou-se robusto, à medida que as recomendações das legislações pertinentes ao equipamento avaliado foram incorporadas, com algumas adaptações para sua exequibilidade. A aplicação do método proposto permitiu atestar a eficácia do equipamento utilizado na desinfecção de alto nível de endoscópios. o método pode servir de referência para a avaliação de reprocessadoras de endoscópios flexíveis, subsidiando a aquisição dessa categoria de produtos para a saúde. elaborar y aplicar un método para evaluar la eficacia de reprocesadores automatizados de endoscopios flexibles en un momento en el que no hay un método oficial o laboratorios capacitados para cumplir con los requisitos descritos en las normas específicas para este tipo de producto para la salud en Brasil. el presente estudio metodológico fue desarrollado en base a las siguientes referencias teóricas: Organización Internacional de Normalización (International Organization for Standardization - ISO) norma ISO 15883-4/2008 y Agencia Nacional de Vigilancia de la Salud de Brasil (Agência Nacional de Vigilância Sanitária - ANVISA) Resolución del Directorio Colegiado (Resolução de Diretoria Colegiada - RDC) № 35/2010 y 15/2012. El método propuesto se aplicó a un dispositivo comercialmente disponible usando un desinfectante al 0,2% a base de ácido peracético de alto nivel. el método de evaluación propuesto se evaluó como fuerte después de que las recomendaciones formuladas en la legislación pertinente se incorporaron con algunos ajustes para garantizar su factibilidad. La aplicación del método propuesto proporciona evidencia de la eficacia de los equipos de prueba para la desinfección de alto nivel de endoscopios. el método propuesto puede servir de referencia para la evaluación de reprocesadores de endoscopios flexibles, proporcionando de este modo bases sólidas para la compra de esta categoría de productos de salud.

Nursing diagnoses in patients with immune-bullous dermatosis.

PubMed

Brandão, Euzeli da Silva; Santos, Iraci Dos; Lanzillotti, Regina Serrão; Ferreira, Adriano Menis; Gamba, Mônica Antar; Azulay-Abulafia, Luna

2016-08-15

identify nursing diagnoses in patients with immune-bullous dermatosis. a quantitative and descriptive research, carried out in three institutions located in Rio de Janeiro and Mato Grosso do Sul, Brazil, using the Client Assessment Protocol in Dermatology during a nursing consultation. Simple descriptive statistics was used for data analysis. 14 subjects participated in the study, nine with a diagnosis of pemphigus vulgaris, pemphigus two and three of bullous pemphigoid. The age ranged between 27 and 82 years, predominantly females (11). 14 nursing diagnoses were discussed and identified from a clinical rationale in all study participants, representing the most common human responses in this sample. The application of the Assessment Protocol in Dermatology facilitated the comprehensive assessment, in addition to providing the identification of diagnostics according to the North American Nursing Diagnosis Association International. the nursing diagnoses presented confirm the necessity of interdisciplinary work during the care for this clientele. For better description of the phenomena related to the client in question, it is suggested the inclusion of two risk factors related in three diagnoses of this taxonomy. It is worth noting the contribution of the findings for the care, education and research in nursing in dermatology. identificar diagnósticos de enfermagem em clientes com dermatoses imunobolhosas. pesquisa quantitativa e descritiva, realizada em três instituições localizadas no Rio de Janeiro e no Mato Grosso do Sul-Brasil, aplicando o Protocolo de Avaliação do Cliente em Dermatologia, durante consulta de enfermagem. Utilizou-se a estatística descritiva simples para análise dos dados. participaram do estudo 14 sujeitos, nove com diagnóstico médico de pênfigo vulgar, dois de foliáceo e três de penfigoide bolhoso. A idade variou entre 27 e 82 anos, predominando 11 pessoas do sexo feminino. Foram discutidos 14 diagnósticos de enfermagem identificados a partir do raciocínio clínico, em todos os participantes do estudo, representando as respostas humanas mais frequentes nesta amostra. A aplicação do Protocolo de Avaliação do Cliente em Dermatologia facilitou a avaliação integral, além de propiciar a identificação dos diagnósticos de acordo com a North American Nursing Diagnosis Association International. os diagnósticos de enfermagem apresentados ratificam a necessidade do trabalho interdisciplinar durante atendimento a esta clientela. Para melhor descrição dos fenômenos relacionados à clientela em questão, sugere-se a inclusão de dois fatores de risco/relacionados em três diagnósticos desta taxonomia. Cabe ressaltar a contribuição dos achados para o cuidar/educar/pesquisar em enfermagem em dermatologia. identificar los diagnósticos de enfermería en pacientes con inmuno dermatosis ampollosa. investigación cuantitativa y descriptiva, realizada en tres instituciones ubicadas en Río de Janeiro y Mato Grosso do Sul, Brasil, utilizando el Protocolo de Evaluación del Cliente en Dermatología en la consulta de enfermería. Se utilizó estadística descriptiva simples para el análisis de datos. 14 sujetos participaron en el estudio, nueve con diagnóstico de pénfigo vulgar, dos de pénfigo foliáceo y tres de penfigoide ampolloso. La edad osciló entre 27 y 82 años, predominio femenino con 11 mujeres. Se discutieron 14 diagnósticos de enfermería identificados desde el razonamiento clínico, en todos los participantes en el estudio, que representa las respuestas humanas más comunes en esta muestra. La aplicación del Protocolo de Evaluación de Dermatología facilitó la evaluación global, además de proporcionar la identificación de los diagnósticos de acuerdo con la North American Nursing Diagnosis Association International. los diagnósticos de enfermería presentados confirman la necesidad del trabajo interdisciplinario en el servicio a estos clientes. Para una mejor descripción de los fenómenos relacionados con los clientes en cuestión, se sugiere la inclusión de dos factores de riesgo/relacionados en tres diagnósticos de esta taxonomía. Vale la pena señalar la contribución de los hallazgos para el cuidado/educación/investigación en enfermería en dermatología.

Translation and cross-cultural adaptation of the Clinical Competence Questionnaire for use in Brazil.

PubMed

Kwiatkoski, Danielle Ritter; Mantovani, Maria de Fátima; Pereira, Evani Marques; Bortolato-Major, Carina; Mattei, Ângela Taís; Peres, Aida Maris

2017-06-05

translating and transculturally adapting the Clinical Competence Questionnaire to Brazilian senior undergraduate Nursing students, as well as measuring psychometric properties of the questionnaire. a methodological study carried out in six steps: translation of the Clinical Competence Questionnaire instrument, consensus of the translations, back-translation, analysis by an expert committee, pre-testing and then presentation of the cross-cultural adaptation process to the developers. Psychometric properties were measured using Cronbach's alpha, intraclass correlation coefficient and content validity index. the instrument was translated, transculturally adapted and its final version consisted of 48 items. Cronbach's alpha coefficient was 0.90, and the agreement index of the items was 99% for students and 98% for evaluators. the Clinical Competence Questionnaire was translated and adapted to Brazilian students, and the psychometric properties of the Portuguese version of the questionnaire presented satisfactory internal consistency regarding the studied sample. traduzir e adaptar transculturalmente o Clinical Competence Questionnaire aos estudantes brasileiros concluintes da graduação em enfermagem, bem como mensurar as propriedades psicométricas do questionário. estudo metodológico realizado em seis etapas: tradução do instrumento Clinical Competence Questionnaire, consenso das traduções, retrotradução, análise pelo comitê de especialistas, pré-teste e apresentação do processo de adaptação transcultural para os desenvolvedores. As propriedades psicométricas foram mensuradas utilizando-se o alfa de Cronbach, coeficiente de correlação intraclasse e índice de validade de conteúdo. o instrumento foi traduzido, adaptado transculturalmente e sua versão final foi constituída de 48 itens. O coeficiente alfa de Cronbach foi de 0,90, e o índice de concordância dos itens foi de 99% para os estudantes e de 98% para os avaliadores. o Clinical Competence Questionnaire foi traduzido e adaptado a estudantes brasileiros, e as propriedades psicométricas da versão em português do questionário apresentaram consistência interna satisfatória quanto à amostra estudada. traducir y adaptar transculturalmente el Clinical Competence Questionnaire para uso de los estudiantes brasileños que concluyen la graduación en enfermería, así como para medir las propiedades psicométricas del cuestionario. estudio metodológico realizado en seis etapas: traducción del instrumento Clinical Competence Questionnaire, obtención de consenso de las traducciones, retrotraducción, análisis por el comité de especialistas, pretest y presentación del proceso de adaptación transcultural para los desarrolladores. Las propiedades psicométricas fueron medidas utilizando el alfa de Cronbach, coeficiente de correlación intraclase e índice de validez de contenido. el instrumento fue traducido, adaptado transculturalmente y su versión final estuvo constituida por 48 ítems. El coeficiente alfa de Cronbach fue de 0,90; el índice de concordancia de los ítems fue de 99% para los estudiantes y de 98% para los evaluadores. el Clinical Competence Questionnaire fue traducido y adaptado para uso de estudiantes brasileños; las propiedades psicométricas, de la versión en portugués del cuestionario, presentaron consistencia interna satisfactoria encontrada en la muestra estudiada.

The Diterpene Sclareol Vascular Effect in Normotensive and Hypertensive Rats.

PubMed

Campos, Debora Ribeiro; Celotto, Andrea Carla; Albuquerque, Agnes Afrodite S; Ferreira, Luciana Garros; Monteiro, Ariadne Santana E Neves; Coelho, Eduardo Barbosa; Evora, Paulo Roberto Barbosa

2017-06-29

The diterpene Sclareol has antimicrobial action, cytotoxic and cytostatic effects and anti-tumor activities. However, researches on the cardiovascular system are scarce. This study was designed to investigate the mechanisms involved in the Sclareol cardiovascular effect in normotensive and hypertensive rats. The arterial hypertension was promoted using 2-kidneys 1-clip model in rats. The effect of sclareol on blood pressure was performed by using three dose (10, 20 and 40 mg/kg). Cumulative dose-response curves for Sclareol were determined for endothelium-intact and endothelium-denuded aortic rings in presence or absence of L-NAME and ODQ. The NOx levels were measure in the plasma sample. The Sclareol administration in vivo caused a significant reduction in blood pressure in both groups. In vitro the sclareol promoted relaxation in aorta, with endothelium, pre-contracted to Phe. The inhibitors of the nitric oxide synthase and soluble guanylate cyclase were as efficient as the removal of endothelium, in inhibiting the Sclareol-induced relaxation. Otherwise, it was no change of NOx. Also, for unknown reasons, the Sclareol is not selective for hypertensive animals. The diterpene Sclareol showed in vivo hypotensive and in-vitro vasodilator effects; The chemiluminescence plasmatic NO analysis showed no significant difference between groups and The Sclareol exhibit better effect on normotensive than hypertensive animals to reduce blood pressure. It is concluded that the diterpenes metabolites would be a promising source prototype for the development of new agents in the cardiovascular therapy. O diterpeno Esclareol tem ação antimicrobiana, efeitos citotóxicos e citostáticos e atividades antitumorais. No entanto, pesquisas sobre o sistema cardiovascular são escassas. Este estudo foi desenvolvido para investigar os mecanismos envolvidos no efeito cardiovascular de Esclareol em ratos normotensos e hipertensos. A hipertensão arterial foi promovida utilizando modelo de 2 clones de 1-clipe em ratos. O efeito do esclareol sobre a pressão arterial foi realizado utilizando três doses (10, 20 e 40 mg/kg). As curvas dose-resposta cumulativas para Esclareol foram determinadas para anéis aórticos endotélio-intactos e desprovidos de endotélio na presença ou ausência de L-NAME e ODQ. Os níveis de NOx foram medidos na amostra de plasma. A administração de Esclareol in vivo causou uma redução significativa na pressão sanguínea em ambos os grupos. In vitro o esclareol promoveu relaxamento na aorta, com endotélio, pré-contraído a Phe. Os inibidores da óxido nítrico sintase e da guanilato ciclase solúvel foram tão eficientes quanto a remoção do endotélio, na inibição do relaxamento induzido por Esclareol. Por outra parte, não houve mudança de NOx. Além disso, por razões desconhecidas, o Sclareol não é seletivo para animais hipertensos. O diterpeno Esclareol apresentou efeitos hipotensores in vivo e vasodilatadores in vitro; A análise de NO plasmático por quimioluminescência não mostrou diferença significativa entre os grupos e O Esclareol exibe melhor efeito sobre os animais normotensos do que hipertensos para reduzir a pressão arterial. Conclui-se que os metabólitos de diterpenos seriam um protótipo de fonte promissora para o desenvolvimento de novos agentes na terapia cardiovascular.

Variabilidad de la Estación de Crecimiento en la Región Sur de Tamaulipas en condiciones climaticas actuales y futuras.

NASA Astrophysics Data System (ADS)

Medina-Barrios, M.; Conde-Alvarez, C.; Gay-Garcia, C.

2007-05-01

El impacto de la variabilidad y cambio climáticos, afectan el potencial agrícola de la Región Sur de Tamaulipas. Además de los cambios estacionales, bajos rendimientos agrícolas, el manejo de los cultivos y las políticas locales de producción, existe la incertidumbre del mercado regional para los pequeños y grandes productores. La diversificación agrícola ha sido una alternativa para enfrentar las condiciones imperantes en esta región. Pero ésta ha provocado la fragmentación territorial, por lo que sólo algunos productores logran competir en un mercado nacional. Existe una preocupación generalizada por buscar soluciones que permitan que la población que es afectada por la inseguridad de la producción agrícola y económica, pueda adaptarse a las variaciones climáticas que afectan el proceso productivo. La seguridad alimentaría queda sujeta a la fluctuación de las importaciones para los sectores básicos y a las estrategias mercantiles de empresas trasnacionales. La percepción local sugiere un número creciente de eventos climatológicos extremos, constantes y severos en los últimos 20 años, con el aumento creciente de pérdidas económicas. El análisis se centra en la disponibilidad de agua, agregándose un aspecto de capital importancia como es la variabilidad interanual de la lluvia, que condiciona muy fuertemente el riesgo agrícola en el trópico seco, siendo ésta la que determina el momento de inicio de la estación favorable para el crecimiento y su duración. En este trabajo se han obtenido modelos de la distribución espacial de la precipitación y temperaturas, para el escenario base 1961-1990, el escenario actual 1971-2000, para algunos años El Niño y La Niña, así como para los escenarios de Cambio Climático HADLEY, ECHAM y GFDL, con escenarios A2 y B2, para las décadas de los 20s y 50s, para establecer el inicio y duración de la Estación de Crecimiento, utilizando Sistemas de Información Geográfica (ArcView). Estos resultados serán utilizados por los administradores de las decisiones locales, para estrategias de manejo y para la difusión entre los habitantes, de tal manera que esto les permita establecer prioridades en las medidas de mitigación, y formular las posibilidades de adaptación.

Clasificación de asterismos utilizando datos astrométricos

NASA Astrophysics Data System (ADS)

de Biasi, M. S.; Orellana, R. B.

Based on accurate positions and proper motion data up to faint magnitudes, we have studied the regions of twenty three objects known in the literature as asterisms. A parametric method was applied to confirm the nature of these objects. The following objects have been classified: Alessi 11, Alessi 17, Brosch 1, Collinder 21, Dol-Dzim 1, Dolidze 31, Dolidze 43, Dolidze 50, Dolidze 51, NGC 272, NGC2063, NGC 2413, NGC 2664, NGC 5155, NGC 5284, NGC 6222, NGC 6360, NGC 6447, NGC 6476, NGC 6480, NGC 6605, NGC 6659, NGC 6728. FULL TEXT IN SPANISH

Dispersal and longevity of wild and mass-reared Anastrepha Ludens and Anastrepha Obliqua (Diptera: Tephritidae)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, E.; Orozco, D.; Flores Breceda, S.

The rates of dispersal and survival of sterile mass-reared laboratory flies and sterile wild flies of Anastrepha ludens (Loew) and Anastrepha obliqua (Macquart) were estimated and compared with a regular rectangular array of 64 food-baited traps spaced 60 m between traps around the release point in Tapachula Chiapas, Mexico. The traps were scored every day during the first week, and then every 3 d over a 30-d period. For A. obliqua, the number of males recaptured was higher than that of females, while for A. ludens, females were recaptured more frequently than males. The recapture rate for the wild strainsmore » ranged from 0.6-24.8% for A. ludens and 1.3-16.2% for A. obliqua and the corresponding ranges for the mass-reared strains were 0.5-7.1% and 0.5-3.0% respectively. The life expectancy was 4.7 d for wild and 4.3 d for mass-reared A. obliqua males but 3 and 2 d, respectively, for wild and mass-reared A. ludens males. The net displacement of A. ludens and A. obliqua ranged approximately from 100-250 m and took place mostly on the first day. Wild A. ludens moved to the northwest from the release point while the mass-reared strain moved to the west. The A. obliqua wild flies moved to the west, while the mass-reared strain shifted to the southwest. We discuss the implications of our findings as to the spacing and frequency of sterile fly releases for the suppression of wild populations. (author) [Spanish] La dispersion y longevidad de las moscas esteriles silvestres y de cria masiva de Anastrepha ludens (Loew) y A. obliqua (Macquart) fueron determinadas y comparadas utilizando un arreglo rectangular de 64 trampas espaciadas a 60 metros entre trampas alrededor del punto de liberacion en Tapachula Chiapas, Mexico. Las trampas fueron revisadas y evaluadas diariamente durante la primera semana y despues cada tres dias hasta completar 30 dias. Para A. obliqua la cantidad de machos capturados fue mayor que la cantidad de hembras; mientras que para A. ludens las hembras fueron capturadas con mayor frecuencia que los machos. La recaptura de moscas silvestres de A. ludens fue de 0.6 a 24.8%, para A. obliqua fue del 1.3 al 16.2%, para moscas de laboratorio fue de 0.5 a 7.1 y 0.5 a 3%, respectivamente. La esperanza de vida correspondio a 4.7 y 4.3 dias para machos silvestres y de laboratorio de A. obliqua respectivamente; mientras que 3 y 2 dias fueron para los machos silvestres y de laboratorio de A. ludens . La dispersion para A. ludens y A. obliqua fue de 100 a 250 m tanto para individuos silvestres como de laboratorio. Los adultos de A. ludens silvestre se desplazaron del punto central de liberacion al noroeste, los individuos de laboratorio se movieron hacia el oeste del plano Cartesiano. A su vez los adultos de A. obliqua silvestre se movieron hacia el oeste y las de laboratorio hacia el suroeste. Discutimos las implicaciones de nuestros resultados con relacion al espaciamiento y frecuencia de las liberaciones de moscas esteriles para la supresion de poblaciones silvestres. (author)« less

Prediction of alcohol drinking in adolescents: Personality-traits, behavior, brain responses, and genetic variations in the context of reward sensitivity.

PubMed

Heinrich, Angela; Müller, Kathrin U; Banaschewski, Tobias; Barker, Gareth J; Bokde, Arun L W; Bromberg, Uli; Büchel, Christian; Conrod, Patricia; Fauth-Bühler, Mira; Papadopoulos, Dimitri; Gallinat, Jürgen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Ittermann, Bernd; Mann, Karl; Martinot, Jean-Luc; Paus, Tomáš; Pausova, Zdenka; Smolka, Michael; Ströhle, Andreas; Rietschel, Marcella; Flor, Herta; Schumann, Gunter; Nees, Frauke

2016-07-01

Adolescence is a time that can set the course of alcohol abuse later in life. Sensitivity to reward on multiple levels is a major factor in this development. We examined 736 adolescents from the IMAGEN longitudinal study for alcohol drinking during early (mean age=14.37) and again later (mean age=16.45) adolescence. Conducting structural equation modeling we evaluated the contribution of reward-related personality traits, behavior, brain responses and candidate genes. Personality seems to be most important in explaining alcohol drinking in early adolescence. However, genetic variations in ANKK1 (rs1800497) and HOMER1 (rs7713917) play an equal role in predicting alcohol drinking two years later and are most important in predicting the increase in alcohol consumption. We hypothesize that the initiation of alcohol use may be driven more strongly by personality while the transition to increased alcohol use is more genetically influenced. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Nexus copy number software for CNV detection and analysis.

PubMed

Darvishi, Katayoon

2010-04-01

Among human structural genomic variation, copy number variants (CNVs) are the most frequently known component, comprised of gains/losses of DNA segments that are generally 1 kb in length or longer. Array-based comparative genomic hybridization (aCGH) has emerged as a powerful tool for detecting genomic copy number variants (CNVs). With the rapid increase in the density of array technology and with the adaptation of new high-throughput technology, a reliable and computationally scalable method for accurate mapping of recurring DNA copy number aberrations has become a main focus in research. Here we introduce Nexus Copy Number software, a platform-independent tool, to analyze the output files of all types of commercial and custom-made comparative genomic hybridization (CGH) and single-nucleotide polymorphism (SNP) arrays, such as those manufactured by Affymetrix, Agilent Technologies, Illumina, and Roche NimbleGen. It also supports data generated by various array image-analysis software tools such as GenePix, ImaGene, and BlueFuse. (c) 2010 by John Wiley & Sons, Inc.

Early Cannabis Use, Polygenic Risk Score for Schizophrenia and Brain Maturation in Adolescence.

PubMed

French, Leon; Gray, Courtney; Leonard, Gabriel; Perron, Michel; Pike, G Bruce; Richer, Louis; Séguin, Jean R; Veillette, Suzanne; Evans, C John; Artiges, Eric; Banaschewski, Tobias; Bokde, Arun W L; Bromberg, Uli; Bruehl, Ruediger; Buchel, Christian; Cattrell, Anna; Conrod, Patricia J; Flor, Herta; Frouin, Vincent; Gallinat, Jurgen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Lemaitre, Herve; Martinot, Jean-Luc; Nees, Frauke; Orfanos, Dimitri Papadopoulos; Pangelinan, Melissa Marie; Poustka, Luise; Rietschel, Marcella; Smolka, Michael N; Walter, Henrik; Whelan, Robert; Timpson, Nic J; Schumann, Gunter; Smith, George Davey; Pausova, Zdenka; Paus, Tomáš

2015-10-01

Cannabis use during adolescence is known to increase the risk for schizophrenia in men. Sex differences in the dynamics of brain maturation during adolescence may be of particular importance with regard to vulnerability of the male brain to cannabis exposure. To evaluate whether the association between cannabis use and cortical maturation in adolescents is moderated by a polygenic risk score for schizophrenia. Observation of 3 population-based samples included initial analysis in 1024 adolescents of both sexes from the Canadian Saguenay Youth Study (SYS) and follow-up in 426 adolescents of both sexes from the IMAGEN Study from 8 European cities and 504 male youth from the Avon Longitudinal Study of Parents and Children (ALSPAC) based in England. A total of 1577 participants (aged 12-21 years; 899 [57.0%] male) had (1) information about cannabis use; (2) imaging studies of the brain; and (3) a polygenic risk score for schizophrenia across 108 genetic loci identified by the Psychiatric Genomics Consortium. Data analysis was performed from March 1 through December 31, 2014. Cortical thickness derived from T1-weighted magnetic resonance images. Linear regression tests were used to assess the relationships between cannabis use, cortical thickness, and risk score. Across the 3 samples of 1574 participants, a negative association was observed between cannabis use in early adolescence and cortical thickness in male participants with a high polygenic risk score. This observation was not the case for low-risk male participants or for the low- or high-risk female participants. Thus, in SYS male participants, cannabis use interacted with risk score vis-à-vis cortical thickness (P = .009); higher scores were associated with lower thickness only in males who used cannabis. Similarly, in the IMAGEN male participants, cannabis use interacted with increased risk score vis-à-vis a change in decreasing cortical thickness from 14.5 to 18.5 years of age (t137 = -2.36; P = .02). Finally, in the ALSPAC high-risk group of male participants, those who used cannabis most frequently (≥61 occasions) had lower cortical thickness than those who never used cannabis (difference in cortical thickness, 0.07 [95% CI, 0.01-0.12]; P = .02) and those with light use (<5 occasions) (difference in cortical thickness, 0.11 [95% CI, 0.03-0.18]; P = .004). Cannabis use in early adolescence moderates the association between the genetic risk for schizophrenia and cortical maturation among male individuals. This finding implicates processes underlying cortical maturation in mediating the link between cannabis use and liability to schizophrenia.

Quality of life and religious-spiritual coping in palliative cancer care patients.

PubMed

Matos, Ticiane Dionizio de Sousa; Meneguin, Silmara; Ferreira, Maria de Lourdes da Silva; Miot, Helio Amante

2017-07-10

to compare the quality of life and religious-spiritual coping of palliative cancer care patients with a group of healthy participants; assess whether the perceived quality of life is associated with the religious-spiritual coping strategies; identify the clinical and sociodemographic variables related to quality of life and religious-spiritual coping. cross-sectional study involving 96 palliative outpatient care patient at a public hospital in the interior of the state of São Paulo and 96 healthy volunteers, using a sociodemographic questionnaire, the McGill Quality of Life Questionnaire and the Brief Religious-Spiritual Coping scale. 192 participants were interviewed who presented good quality of life and high use of Religious-Spiritual Coping. Greater use of negative Religious-Spiritual Coping was found in Group A, as well as lesser physical and psychological wellbeing and quality of life. An association was observed between quality of life scores and Religious-Spiritual Coping (p<0.01) in both groups. Male sex, Catholic religion and the Brief Religious-Spiritual Coping score independently influenced the quality of life scores (p<0.01). both groups presented high quality of life and Religious-Spiritual Coping scores. Male participants who were active Catholics with higher Religious-Spiritual Coping scores presented a better perceived quality of life, suggesting that this coping strategy can be stimulated in palliative care patients. comparar a qualidade de vida e o coping religioso-espiritual de pacientes em cuidados paliativos oncológicos com um grupo de participantes sadios; avaliar se a percepção de qualidade de vida está associada às estratégias de coping religioso-espiritual; identificar as variáveis clínicas e sociodemográficas relacionadas à qualidade de vida e ao coping religioso-espiritual. estudo transversal, realizado com 96 pacientes de ambulatório de cuidados paliativos, em um hospital público no interior do Estado de São Paulo, e 96 voluntários saudáveis, por meio de questionário utilizando dados sociodemográficos, o McGill Quality of Life Questionnaire e o Coping Religioso-Espiritual-Breve. foram entrevistados 192 participantes que apresentaram boa qualidade de vida e alta utilização do Coping Religioso-Espiritual. Houve maior uso de Coping Religioso-Espiritual negativo no Grupo A, assim como menor bem-estar físico, psicológico e de qualidade de vida. Observou-se associação entre escores de qualidade de vida e Coping Religioso-Espiritual (p<0,01) em ambos os grupos. Sexo masculino, religião católica e escore de Coping Regioso-Espiritual-Breve influenciaram, de forma independente, os escores de qualidade de vida (p<0,01). ambos os grupos apresentaram escores altos de qualidade de vida e de Coping Espiritual-Religioso. Participantes do sexo masculino, praticantes de religião católica e com maiores escores de Coping Espiritual-Religioso apresentaram melhor percepção de qualidade de vida, sugerindo que essa estratégia de enfrentamento possa ser estimulada em pacientes sob cuidados paliativos. comparar la calidad de vida y el coping religioso-espiritual de pacientes en cuidados paliativos oncológicos con un grupo de participantes sanos; evaluar si la calidad de vida percibida está asociada a las estrategias de coping religioso-espiritual; identificar las variables clínicas y sociodemográficas relacionadas a la calidad de vida y al coping religioso-espiritual. estudio transversal, desarrollado con 96 pacientes de ambulatorio de cuidados paliativos en un hospital público en el interior del Estado de São Paulo, Brasil, y 96 voluntarios sanos, mediante cuestionario utilizando datos sociodemográficos, el McGill Quality of Life Questionnaire y el Coping Religioso-Espiritual-Breve. fueron entrevistados 192 participantes que presentaron buena calidad de vida y alta utilización del Coping Religioso-Espiritual. Fue encontrado mayor uso de Coping Religioso-Espiritual negativo en el Grupo A, y también menor bienestar físico, psicológico y de calidad de vida. Fue observada asociación entre los scores de calidad de vida y Coping Religioso-Espiritual (p<0,01) en ambos grupos. Sexo masculino, religión católica y score de Coping Religioso-Espiritual-Breve influenciaron de manera independiente los scores de calidad de vida (p<0,01). ambos grupos presentaron altas puntuaciones de calidad de vida y de Coping Espiritual-Religioso. Participantes do sexo masculino, practicantes de religión católica y con mayores scores de Coping Espiritual-Religioso presentaron mejor percepción de calidad de vida, sugiriendo la posibilidad de estimular esa estrategia de enfrentamiento en pacientes bajo cuidados paliativos.

Assessment of risk of falls in elderly living at home.

PubMed

Smith, Adriana de Azevedo; Silva, Antonia Oliveira; Rodrigues, Rosalina Aparecida Partezani; Moreira, Maria Adelaide Silva Paredes; Nogueira, Jordana de Almeida; Tura, Luiz Fernando Rangel

2017-04-06

to assess the risk of falls in elderly, by comparing the sociodemographic and cognitive factors, history of falls and self-reported comorbidities. cross-sectional and quantitative study with 240 elderly. Data were collected based on the social profile, through the instrument of risk of falls and assessment of falls, by univariate analysis, bivariate and multiple logistic regression. The Statistical Package for the Social Sciences (SPSS) version 19 was used for statistical analysis. there was a significant association of the risk of falls, as measured by the Fall Risk Score, with sex (<0.001), age (0.054), cognitive status (<0.001) and history of falls (<0.001). All variables were statistically significant and contributed to the occurrence of falls. In logistic regression, the variables that showed association with risk of falls were: fall, with whom they live, hypertension and visual impairment. female gender, older elderly (over 80 years old), with low cognitive status and occurrence of previous falls in the last six months are factors that increase the prevalence of falls. In logistic regression, the variables that were associated with risk of falls were: fall, with whom they live, visual impairment and rheumatologic diseases. avaliar o risco de quedas em idosos, comparando com os fatores sóciodemográficos, cognitivos, presença de quedas e co-morbidades autorreferidas. Estudo transversal e quantitativo com 240 idosos. Os dados foram coletados a partir do perfil social, instrumento do risco de quedas e avaliação de quedas, utilizando análise univariada, bivariada e regressão logística múltipla. Para a análise estatística, utilizou-se o Statistical Package for the Social Sciences (SPSS) versão 19. há associação entre o risco de quedas, mensurado pelo Fall Risk Score, com o sexo (<0,001), a faixa etária (0,054), o desempenho cognitivo (<0,001) e a presença de quedas (<0,001). Todas as variáveis apresentaram significância estatística e contribuíram para a ocorrência das quedas. Na regressão logística, as variáveis que apresentaram associação com o risco de quedas foram: queda, com quem mora, hipertensão arterial e déficit visual. sexo feminino, idoso mais velho (acima de 80 anos), com baixo desempenho cognitivo e apresentar quedas anteriores nos últimos seis meses, aumentam a prevalência de quedas. Na regressão logística, as variáveis que apresentaram associação com o risco de quedas foram: queda, com quem mora, visão prejudicada e doenças reumatológicas. evaluar el riesgo de caídas del adulto mayor, mediante la comparación de los factores cognitivos y sociodemográficos, antecedentes de caídas y comorbilidades auto-reportadas. estudio transversal y cuantitativo con 240 adultos mayores. Los datos fueron recolectados utilizando instrumento del riesgo de caídas y evaluación de caídas, mediante el análisis univariado, bivariado y regresión logística múltiple. Para el anpalisis estadístico, fue utilizado software Statistical Package for the Social Sciences (SPSS) versión 19, se utilizó en el análisis estadístico. hay una asociación significativa del riesgo de caídas, medido por el Fall Risk Score, con el sexo (<0.001), la edad (0.054), el desempeño cognitivo (<0.001) y los antecedentes de caídas (<0.001). Todas las variables fueron estadísticamente significativas y contribuyeron a la ocurrencia de caídas. En la regresión logística, las variables que mostraron asociación con el riesgo de caídas fueron: caída, con quien viven, hipertensión y discapacidad visual. sexo femenino, adulto mayor de edad más avanzada (más de 80 años de edad), bajo desempeño cognitivo, y antecedentes de caídas en los últimos seis meses son factores que aumentan la prevalencia de caídas. En la regresión logística, las variables que mostraron asociación con el riesgo de caídas fueron: caída, con quien vive, discapacidad visual y enfermedades reumáticas.

One-pot synthesis of hollow NiSe-CoSe nanoparticles with improved performance for hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Haichao; Fan, Meiqiang; Li, Chao; Tian, Guanglei; Lv, Chunju; Chen, Da; Shu, Kangying; Jiang, Jianjun

2016-10-01

Hollow NiSe-CoSe samples have been synthesized for the first time via a one-pot solvothermal approach. The strategy is robust enough to synthesize NiSe-CoSe nanoparticles with different NiSe to CoSe ratios but with a similar hollow structure. Co ions in the NiSe-CoSe nanoparticles play decisive role for formation of the hollow structure; otherwise, the nanoparticles become solid for the NiSe sample. When used as the positive electroactive materials for energy storage, the NiSe-CoSe samples show excellent electrochemical activity in alkaline electrolyte. Using the synergistic effect between NiSe and CoSe, the electrochemical performance of NiSe-CoSe can be tuned by varying the NiSe to CoSe ratios. The NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 shows the best electrochemical performance in terms of superior specific capacity, improved rate capability and excellent cycling stability. In addition, the electrochemical performance of NiSe-CoSe sample with a NiSe to CoSe ratio of 4:2 is also evaluated via assembling hybrid supercapacitors with RGO, and the hybrid supercapacitor delivers both high power and energy densities (41.8 Wh kg-1 at 750 W kg-1 and 20.3 Wh kg-1 at 30 kW kg-1).

Selenium fractions in organic matter from Se-rich soils and weathered stone coal in selenosis areas of China.

PubMed

Qin, Hai-bo; Zhu, Jian-ming; Su, Hui

2012-02-01

A high degree of association between Selenium (Se) and organic matter has been demonstrated in natural environments, but Se fractions and speciation in organic matter is unclear. In this study, a method for quantifying organic matter associated with Se (OM-Se) was developed to investigate Se fractions in organic matter in Se-rich soils and weathered stone coal from Enshi, China, where Se poisoning of humans and livestock has been documented. Initially, Se was extracted using water and a phosphate buffer. Subsequently, OM-Se was extracted using NaOH, and then speciated into Se associated with fulvic acids (FA-Se) and humic acids (HA-Se). Both FA-Se and HA-Se were further speciated into the weakly bound and strongly bound fractions using a customized hydride generation reactor. The results show that FA-Se (1.91-479 mg kg(-1)) is the predominant form of Se in all Se-rich soils and the weathered stone coal samples, accounting for more than 62% of OM-Se (3.07-484 mg kg(-1)). Weakly bound FA-Se (1.33-450 mg kg(-1)) was prevalent in the total FA-Se, while weakly bound HA-Se (0.62-26.2 mg kg(-1)) was variable in the total HA-Se (1.15-32.5 mg kg(-1)). These data indicate that OM-Se could play a significant source and sink role in the biogeochemical cycling of Se in the supergene environment. Weakly bound FA-Se seems to act as a potential source for bioavailable Se, whereas strongly bound HA-Se is a possible OM-Se sink which is not readily transformed into bioavailable Se. Copyright © 2011 Elsevier Ltd. All rights reserved.

Self-image and perception of mother and father in psychotic and borderline patients.

PubMed

Armelius, K; Granberg

2000-02-01

Psychotic and borderline patients rated their self-image and their perception of their mother and father using the Structural Analysis of Social Behavior model (SASB). The borderline patients had more negative images of themselves and their parents, especially their fathers, than did the psychotic patients and the normal subjects, while the psychotic patients' ratings did not differ much from those of the normal subjects. The self-image was related to the images of both parents for borderline patients and normal subjects, while for the psychotic patients only the image of the mother was important for the self-image. In addition, the psychotic patients did not differentiate between the poles of control and autonomy in the introjected self-image. It was concluded that borderline patients are characterized by negative attachment, while psychotic patients are characterized by poor separation from the mother and poor differentiation between autonomy and control. The paper also discusses how this may influence the patients' relations to others. Psychotische und Borderline Patienten beurteilten ihr Selbstbild und ihre Wahrnehmung von Mutter und Vater mit Hilfe der strukturalen Analyse sozialen Verhaltens (SASB). Die Borderline Patienten hattten negativere Selbstbilder und Elternbilder (speziell Vaterbilder) als die psychotischen Patienten und gesunde Personen. Die Beurteilungen der psychotischen Patienten unterschieden sich dagegen nicht besonders von jenen Gesunder. Das Selbstbild stand in Beziehung zu beiden Elternbildern bei den Borderline Patienten und den Gesunden, während bei den psychotischen Patienten nur das Mutterbild für das Selbstbild bedeutsam war. Außerdem konnte bei den psychotischen Patienten nicht zwischen den Polen der Kontrolle und Autonomie bzgl. der introjizierten Selbstbilder differenziert werden. Aus den Ergebnissen wird gefolgert, dass Borderline Patienten durch eine negative Bindung charackterisiert sind, psychotische Patienten dagegen durch eine mangelnde Separation von ihren Müttern und eine geringe Differenzierung zwischen Autonomie und Kontrolle. Es wird außerdem diskutiert, wie die Ergebnisse auf die realen Beziehungen der Patienten zu anderen Menschen Einflus nehmen könnten. Des patients psychotiques et Borderline ont évalué leur image d'eux-mêmes et leur perception de leur mère et père à l'aide du modèle de l'Analyse Structural du Comportement Social (SASB. Les patients Borderline avaient des imagess plus négatives d'eux-mêmes et de leurs parents, surtout de leur père, que les patients psychotiques et les sujets normaux, alors que les patients psychotiques se jugeaient à peine différemment des sujets normaux. L'image de soi était en relation avec les images des deux parents pour les patients Borderline et pour les sujets normaux, alors que pour les patients psychotiques, seulement l'image de la mère jouait un rôle pour leur image. En plus, les patients psychotiques ne différenciaient pas entre les pôles de contrôle et d'autonomie dans l'image de soi introjectée. Nous en avons conclu que les patients Borderline se caractérisent par un attachement négatif, et les patients psychotiques par une faible séparation de la mère ainsi qu'une différenciation modeste entre autonomie et contrôle. L'influence de ceci sur les relations des patients avec les autrs est discutée dans cet article. Pacientes limítrofes y psicóticos evaluaron su autoimagen y la percepción que tenían de sus padres usando el modelo de Análisis estructural del comportamiento social (SASB). Los pacientes limítrofes registraron imágenes más negativas de sí mismos y de sus progenitores, especialmente de su padre, que los pacientes psicóticos y los normales, mientras que las evaluaciones de los pacientes psicóticos no difirieron mucho de las de los sujetos normales. La autoimagen tuvo relación con la imagen de ambos progenitores tanto en el caso de los pacientes limítrofes como de los sujetos normales, mientras que para los pacientes psicóticos no diferenciaron entre control y autonomía en la autoimagen introyectada. Se concluyó que los pacientes limítrofes se caracterizan por un apego negativo, mientras que los pacientes psicóticos muestran una pobre separación de su madre y también pobre discriminación entre autonomía y control. El trabajo también discute cómo esto puede influire sobre la relación de los pacientes con los demás.

Rumen Microorganisms Decrease Bioavailability of Inorganic Selenium Supplements.

PubMed

Galbraith, M L; Vorachek, W R; Estill, C T; Whanger, P D; Bobe, G; Davis, T Z; Hall, J A

2016-06-01

Despite the availability of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study was to determine whether rumen microorganisms (RMO) alter the bioavailability of Se sources commonly used in Se supplements. Rumen microorganisms were isolated from ewes (n = 4) and incubated ex vivo with no Se (control), with inorganic Na selenite or Na selenate, or with organic selenomethionine (SeMet). Total Se incorporated into RMO and the amount of elemental Se formed were determined under equivalent conditions. Incorporation of Se from Na selenite, Na selenate, or SeMet into RMO was measured as fold change compared with control (no added Se). Incorporation of Se into microbial mass was greater for SeMet (13.2-fold greater than no-Se control) compared with inorganic Se supplements (P = 0.02); no differences were observed between inorganic Na selenate (3.3-fold greater than no-Se control) and Na selenite (3.5-fold greater than no-Se control; P = 0.97). Formation of non-bioavailable, elemental Se was less for RMO incubated with SeMet compared with inorganic Se sources (P = 0.01); no differences were observed between Na selenate and Na selenite (P = 0.09). The clinical importance of these results is that the oral bioavailability of organic SeMet should be greater compared with inorganic Se sources because of greater RMO incorporation of Se and decreased formation of elemental Se by RMO.

Liquidus Projections of Bi-Se-Ga and Bi-Se-Te Ternary Systems

NASA Astrophysics Data System (ADS)

Lin, Po-han; Chen, Sinn-wen; Hwang, Jenn-dong; Chu, Hsu-shen

2016-12-01

This study determines the liquidus projections of both Bi-Se-Ga and Bi-Se-Te ternary systems which are constituent ternary systems of promising Bi-Se-Te-Ga thermoelectric materials. Ternary Bi-Se-Ga and Bi-Se-Te alloys are prepared. Their primary solidification phases are experimentally determined, and thermal analysis experiments are carried out. The liquidus projections are determined based on the ternary experimental results and phase diagrams of constituent binary systems. The Bi-Se-Ga system includes seven primary solidification phases, Bi, Ga, GaSe, Ga2Se3, Se, Bi2Se3, and (Bi2)n(Bi2Se3)m. In the Bi-Se-Te system, there are five primary solidification phases, Bi, (Bi2)n(Bi2Te3)m, Bi2(Se,Te)3, (Se,Te), and (Bi2)n(Bi2Se3)m. Both the (Bi2)n(Bi2Te3)m and (Bi2)n(Bi2Se3)m phases are not a single phase, but a collection of series undetermined phases. Large miscibility gaps are observed in the Bi-Se-Ga system. The temperatures of the invariant reactions, Liquid + Bi + GaSe = Ga and Liquid + Ga2Se3 = Bi + GaSe, are at 495 K (222 °C) and 533 K (260 °C), respectively.

Social representations of the health care of the Mbyá-Guarani indigenous population by health workers.

PubMed

Falkenberg, Mirian Benites; Shimizu, Helena Eri; Bermudez, Ximena Pamela Díaz

2017-02-06

to analyze the social representations of health care of the Mbyá-Guarani ethnic group by multidisciplinary teams from the Special Indigenous Health District in the south coast of Rio Grande do Sul state (Distrito Sanitário Especial Indígena Litoral Sul do Rio Grande do Sul), Brazil. a qualitative method based on the theory of social representations was used. Data were collected via semi-structured interviews with 20 health workers and by participant observation. The interviews were analyzed with ALCESTE software, which conducts a lexical content analysis using quantitative techniques for the treatment of textual data. there were disagreements in the health care concepts and practices between traditional medicine and biomedicine; however, some progress has been achieved in the area of intermedicality. The ethnic boundaries established between health workers and indigenous peoples based on their representations of culture and family, together with the lack of infrastructure and organization of health actions, are perceived as factors that hinder health care in an intercultural context. a new basis for the process of indigenous health care needs to be established by understanding the needs identified and by agreement among individuals, groups, and health professionals via intercultural exchange. analisar as representações sociais do cuidado em saúde entre trabalhadores que atuam em equipes multidisciplinares no Distrito Sanitário Especial Indígena Litoral Sul do Rio Grande do Sul, junto à etnia Mbyá-Guarani. utilizou-se método qualitativo, fundamentado na teoria das Representações Sociais. Os dados foram coletados por meio de entrevistas semiestruturadas com 20 trabalhadores e da observação participante. As entrevistas analisadas com o software ALCESTE, o qual realiza a análise lexical de conteúdo por meio de técnicas quantitativas de tratamento de dados textuais. verificou-se que existe tensão entre as concepções e práticas de cuidado da medicina tradicional e da biomedicina, mas observam-se alguns avanços na perspectiva da intermedicalidade. Fronteiras étnicas estabelecidas entre os trabalhadores e os indígenas, baseadas em suas representações de cultura e família, da mesma maneira que a falta de infraestrutura e os modos de organização do trabalho em saúde são percebidos como fatores que dificultam o cuidado em contextos de interculturalidade. é preciso estabelecer novas bases para o processo de cuidar em saúde indígena, a partir da compreensão das necessidades representadas, negociadas entre sujeitos individuais e coletivos e os profissionais nas instituições de saúde em um diálogo intercultural de múltiplas vozes. analizar las representaciones sociales de la atención de la salud del grupo étnico Mbyá-Guaraní por equipos multidisciplinarios del Distrito Sanitario Especial Indígena en la costa sur del estado de Rio Grande do Sul (Distrito Sanitário Especial Indígena Litoral Sul do Rio Grande do Sul), Brasil. se utilizó un método cualitativo basado en la teoría de las representaciones sociales. Los datos fueron recogidos a través de entrevistas semi-estructuradas con 20 trabajadores de la salud y por observación de los participantes. Las entrevistas fueron analizadas con el programa ALCESTE, que realiza un análisis de contenido léxico utilizando técnicas cuantitativas para el tratamiento de datos textuales. hubo desacuerdos en los conceptos y prácticas de atención médica entre medicina tradicional y biomedicina; sin embargo, se han logrado algunos avances en el área de la intermedicina. Las barreras étnicas establecidas entre los trabajadores de la salud y los pueblos indígenas basados en sus representaciones de la cultura y la familia, junto con la falta de infraestructura y organización de las acciones de salud, son percibidas como factores que obstaculizan la atención sanitaria en un contexto intercultural. es necesario establecer una nueva base para el proceso de atención de salud indígena mediante la comprensión de las necesidades identificadas y por acuerdo entre individuos, grupos y profesionales de la salud a través del intercambio intercultural.

Selenium speciation in paired serum and cerebrospinal fluid samples of sheep.

PubMed

Humann-Ziehank, Esther; Ganter, Martin; Michalke, Bernhard

2016-01-01

This study was performed to characterise selenium (Se) and Se species in cerebrospinal fluid (CSF) of sheep and its relation to the respective Se concentrations in serum. Paired samples from 10 adult sheep were used for the study. Five sheep were fed a diet with a marginal Se concentration of <0.05mg Se/kg diet dry weight (dw, Se(-)), and five animals were fed the same diet supplemented with sodium selenite revealing a concentration of 0.2mg Se/kg diet dw (Se(+)). The feeding strategy was conducted for two years; The results on metabolic effects were published previously. At the end of the feeding period, paired samples of serum and CSF were collected and analysed using ion exchange chromatography inductively coupled plasma-dynamic reaction cell-mass spectrometry (IEC-ICP-DRC-MS) technique for total Se concentration and concentrations of Se species. Albumin concentrations were analysed additionally. The feeding strategy caused significant differences (p<0.01) in serum Se concentrations with 33.1±5.11μg Se/l in the Se(-) group and 96.5±18.3μg Se/l in the Se(+) group, respectively. The corresponding total Se concentrations in CSF were 4.38±1.02μg Se/l and 6.13±1.64μg Se/l in the Se(-) and the Se(+) group, respectively, missing statistical significance (p=0.077). IEC-ICP-DRC-MS technique was able to differentiate the Se species selenoprotein P-bound Se (SePP), selenomethionine, glutathione peroxidase-bound Se (Se-GPx), selenocystine, thioredoxin reductase-bound Se, ovine serum albumin-bound Se (Se-OSA), SeIV and SeVI in ovine serum and CSF. Quantitatively, SePP is the main selenoprotein in ovine serum followed by Se-GPx. The CSF/blood ratio of albumin (QAlbumin) reflected a physiological function of the blood-CSF barrier in all sheep. QSe-species were higher than QAlbumin both feeding groups, supporting the hypothesis of local production of Se species in the brain. Significant positive regression lines for CSF vs. serum were found for albumin and Se-OSA only, suggesting a role of albumin to convey Se across the blood-CSF barrier. The ovine model, together with the IEC-ICP-DRC-MS technique to characterise the Se species, might be a worthwhile model for further studies as repeated sample collection as well as modification of the nutritional status is feasible and effective. Copyright © 2015 Elsevier GmbH. All rights reserved.

Effects of Selenium Supplementation on the Diabetic Condition Depend on the Baseline Selenium Status in KKAy Mice.

PubMed

Febiyanto, Novian; Yamazaki, Chiho; Kameo, Satomi; Sari, Dian K; Puspitasari, Irma M; Sunjaya, Deni K; Herawati, Dewi M D; Nugraha, Gaga I; Fukuda, Toshio; Koyama, Hiroshi

2018-01-01

Oxidative stress in obesity leads to insulin resistance in type 2 diabetes. Some selenoproteins possess antioxidant properties, suggesting that selenium (Se) may protect against type 2 diabetes; however, evidence from epidemiological studies is contradictory. We hypothesized that Se status before supplementation (baseline) contributes to the supplementation outcome. This study aimed to clarify the influence of baseline Se status on the effect of Se supplementation on the diabetic condition. Six-week-old KKAy mice were fed a diet without supplemental Se or with 0.1 ppm Se in the form of L-selenomethionine (SeM) for 2 weeks to create low-Se and sufficient-Se baseline statuses, respectively. For the next 4 weeks, low-Se mice were given a SeM (0.5 ppm Se)-supplemented diet, and sufficient-Se mice were given either a SeM (0.5 ppm Se)- or sodium selenite (0.5 ppm Se)-supplemented diet; control groups continued on baseline diets. Serum Se concentrations, glutathione peroxidase (GPx) activities, adiponectin levels, glucose tolerance, and insulin sensitivity were analyzed. All mice became diabetic during the 2-week baseline induction period. At the end of the supplementation period, Se-receiving groups demonstrated significantly higher Se concentrations and GPx activities than their respective controls. Sufficient-Se mice receiving SeM had lower blood glucose levels and better insulin sensitivity than control and sodium selenite-receiving mice, whereas low-Se mice receiving SeM showed no such improvements compared with their controls. Our results suggest that Se supplementation in the form of SeM may help prevent type 2 diabetes aggravation in people taking the 55 μg/day Se recommended dietary allowance.

Asymmetry and Electronegativity in the Electron Capture Activation of the Se-Se Bond: σ*(Se-Se) vs σ*(Se-X).

PubMed

Gámez, José A; Yáñez, Manuel

2010-10-12

The effects of electron capture on the structure of XSeSeX' diselenide derivatives in which the substituents attached to the selenium atoms have different electronegativities have been investigated at different levels of theory, namely, DFT, MP2, CCSD, G2, and CASSCF/CASPT2. An analysis of the bonding changes upon electron attachment shows that when the diselenides bear low-electronegativity substituents, the Se-Se bond becomes activated upon electron capture, as previous studies have shown. However, this is no longer the case for very electronegative substituents, where this bond remains practically unaltered and is the Se-X bond the one which becomes strongly activated through a preferential population of the σ*(Se-X) antibonding orbital rather than the σ*(Se-Se) one. When this is the case, several anionic species are also encountered, namely, stretched, bent, and book structures. The present findings are similar to those obtained for a series of analogous disulfide compounds, which points out that these results are not unique and could be extrapolated to a wider range of compounds than the ones covered here. The Se-Se (Se-X) linkage in CH3SeSeOH, CH3SeSeF, FSeSeOH, and FSeSeF bears some of the characteristics of the so-called charge-shift bonds, with a clear charge fluctuation between both selenium atoms. This is more evident in their anions where the bonding reflects the important contribution of the ionic resonant forms Se-Se(-) ↔ (-)Se-Se vs the covalent component Se∴Se. This resonance changes with the nature of the substituents but also depends on the asymmetry of the substitution.

Selenium speciation in Lower Cambrian Se-enriched strata in South China and its geological implications

NASA Astrophysics Data System (ADS)

Fan, Haifeng; Wen, Hanjie; Hu, Ruizhong; Zhao, Hui

2011-12-01

To understand the impact of Selenium (Se) into the biogeochemical cycle and implications for palaeo-redox environment, a sequential extraction method was utilized for samples including black shales, cherts, a Ni-Mo-Se sulfide layer, K-bentonite and phosphorite from Lower Cambrian Se-enriched strata in southern China. Seven species (water-soluble, phosphate exchangeable, base-soluble, acetic acid-soluble, sulfide/selenide associated, residual Se) and different oxidation states (selenate Se(VI), selenite Se(IV), organic Se, Se (0) and mineral Se(-II)) were determinated in this study. We found that the Ni-Mo-Se sulfide layer contained a significantly greater amount of Se(-II) associated with sulfides/selenides than those in host black shales and cherts. Furthermore, a positive correlation between the degree of sulfidation of iron (DOS) and the percentage of the sulfide/selenide-associated Se(-II) was observed for samples, which suggests the proportion of sulfide/selenide-associated Se(-II) could serve as a proxy for palaeo-redox conditions. In addition, the higher percentage of Se(IV) in K-bentonite and phosphorite was found and possibly attributed to the adsorption of Se by clay minerals, iron hydroxide surfaces and organic particles. Based on the negative correlations between the percentage of Se(IV) and that of Se(-II) in samples, we propose that the K-bentonite has been altered under the acid oxic conditions, and the most of black shale (and cherts) and the Ni-Mo-Se sulfide layer formed under the anoxic and euxinic environments, respectively. Concerning Se accumulation in the Ni-Mo-Se sulfide layer, the major mechanism can be described by (1) biotic and abiotic adsorption and further dissimilatory reduction from oxidized Se(VI) and Se(IV) to Se(-II), through elemental Se, (2) contribution of hydrothermal fluid with mineral Se(-II).

[Preventive effects of 4 Se-enriched plants on rat stomach cancer induced by MNNG--3. Se accumulation and distribution in rats of different selenium resources for prevention of stomach cancer].

PubMed

Yang, Wenije; Chen, Jing; Li, Weidong; Chen, Xiaobin

2008-07-01

To investigate the accumulation and distribution of blood and tissue Se in rats with long-term and high-dose of Se supplementation by four Se-enriched plants (Se-enriched garlic, Se-enriched broccoli, Se-enriched green kale and Se-enriched red kale) in the N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced stomach cancer model. Ninety rats were fed by basal diet for a week, divided equally into the control, MNNG and seven Se supplementation groups. Rats were daily given 15 mg/kg bw of MNNG for ten days except those in the control group, and rats in five Se-enriched plant treatment groups were daily given 150 or 300 microg Se/kg of bw of the plant suspension by gavage for 17 weeks. Rats were sacrificed at the end of 18th week, the Se contents of blood, red blood cell, plasma, liver, kidney, spleen, heart, brain and testicle were determined. The Se contents of liver and kidney in rats supplemented by Se-enriched garlic were significantly lower than those in rats supplemented by Se-enriched broccoli and two Se-enriched kales, and the Se contents of red blood cell and spleen higher than those in rats supplemented by Se-enriched broccoli and two Se-enriched kales. The data primarily shows that the differences of the accumulation and distribution of blood and tissue Se in rats are related to the supplemented plant Se components, and that lower Se accumulation of the liver and kidney in rats supplemented by Se-enriched garlic than by other plants may be one of Se safety indices of Se-enriched garlic.

Proving the Orbits of the Galilean Moons Through Astrophotography. (Spanish Title: Comprobando Las Órbitas de Las Lunas Galileanas a Través de la Astrofotografía.) Evidenciando as Órbitas das Luas Galileanas Atravéd da Astrofotografia

NASA Astrophysics Data System (ADS)

Iachel, Gustavo

2009-12-01

An activity related to the observation of the Galilean moons and to amateur astrophotography is presented in this work. Through the reading of excerpts of the book Sidereus Nuncius (Sidereal Messenger), by Galileo, it is possible to trace a methodology to observe the planet and its natural satellites and, with the aid of the astrophotography, to analyze the field recordings. Moreover, it is possible to compare the images obtained after plotting the relative positions of these moons to prove their orbits. This activity can be conducted by teachers, students and amateur astronomers, in order to develop their capabilities of observation of astronomical phenomena. Se presenta en este trabajo una actividad relacionada a la observación de las lunas Galileanas y a la astrofotografía amateur. A través de la lectura de tramos de la obra Sidereus Nuncius (El Mensajero Sideral) de Galileo, es posible trazar una metodología para la observación del planeta y de sus satélites naturales y, con el auxilio de la astrofotografía, analizar las anotaciones de campo. Además, es posible comparar las imágenes obtenidas con el gráfico de las posiciones relativas de estas lunas para comprobar sus órbitas. Esa actividad puede ser realizada por maestros, estudiantes y astrónomos amateurs, de forma a desarrollar sus capacidades de observación de los fenómenos astronómicos. Uma atividade relacionada à observação das luas Galileanas e à astrofotografia amadora é apresentada neste trabalho. Através da leitura de trechos da obra Sidereus Nuncius (Mensageiro Sideral), de Galileu, é possível traçar uma metodologia para a observação do planeta e de seus satélites naturais e, com o auxílio da astrofotografia, analisar as anotações de campo. Além disso, é possível comparar as imagens obtidas com o gráfico das posições relativas destas luas para evidenciar suas órbitas. Essa atividade pode ser realizada por professores, estudantes e astrônomos amadores, de forma a desenvolverem suas capacidades de observar fenômenos astronômicos.

Use of a severity indicator as a predictor of the use of hepatic transplantation resources.

PubMed

Eiras, Flavia Regina Cocuzza das; Barbosa, Antonio Pires; Leão, Eliseth Ribeiro; Biancolino, César Augusto

2016-01-01

To evaluate the use of a severity indicator for end-stage liver disease as a predictor of resource use in a teaching hospital in São Paulo. Descriptive, retrospective study, classifying independent variables in seven key dimensions: identification/risk rating; length of stay/use of advanced life support; imaging; clinical analysis; special procedures; blood products in the intensive care unit; and in the operating room. The frequencies were analyzed by linear regression analysis of variance to detect relevance due to the dependent variable (severity indicator) in 76 cases seen in 2013. Among the variables studied, those that presented relevance due to the functional risk score were laboratory measurements of bilirubin, amylase, transaminase, blood count, creatine phosphokinase (p<0.05), hemotherapy procedures fresh frozen plasma (FFP) and platelet concentrate (p<0.05), and Doppler echocardiography image (p<0.07). Given the results/objective of this study, it is concluded that the indicator presents a potential predictive capability in the use of postoperative resources of liver receptors in the size, clinical analysis, images and hemotherapy dimensions. Avaliar o uso do indicador de gravidade para doenças hepáticas terminais como fator preditivo do uso de recursos em um hospital-escola de São Paulo. Estudo descritivo, retrospectivo, classificando variáveis independentes em sete dimensões principais: identificação/classificação de risco; tempo de permanência/uso de suporte avançado à vida; exames de imagem; análises clínicas; procedimentos especiais; hemoderivados em unidade de terapia intensiva; e em centro cirúrgico. As frequências foram analisadas por regressão linear com análise de variância para detecção de relevâncias face à variável dependente (indicador de gravidade) em 76 casos atendidos em 2013. Dentre as variáveis estudadas, apresentaram relevância em função do escore de risco funcional as dosagens laboratoriais de bilirrubina, amilase, transaminase, hemograma, creatinofosfoquinase (p<0,05), procedimentos hemoterápicos plasma fresco congelado (PFC) e concentrado de plaquetas (p<0,05), e imagem Ecodoppler (p<0,07). Face aos resultados/propósito do estudo conclui-se que o indicador apresenta potencial capacidade preditiva no uso de recursos pós-operatórios de receptores de fígado nas dimensões, análises clínicas, imagens e hemoterapia.

Elderly who take care of elderly: a study on the Frailty Syndrome.

PubMed

Santos-Orlandi, Ariene Angelini Dos; Brito, Tábatta Renata Pereira de; Ottaviani, Ana Carolina; Rossetti, Estefani Serafim; Zazzetta, Marisa Silvana; Pavarini, Sofia Cristina Iost

2017-01-01

Identifying prevalence of frailty in elderly caregivers inserted in a high social vulnerability context and its correlation with sociodemographic and health aspects. Descriptive, correlational and cross-sectional study. Forty elderly caregivers were evaluated with: questionnaire for caregiver characterization, Mini Mental State Examination, Katz Index, Lawton instrumental activities of daily living scale, Geriatric Depression Scale and the frailty phenotype proposed by Fried. Interviews were conducted at their residences and scheduled in advance. All ethical precautions were observed. Data were analyzed with the Stata statistical program version 11.0. 10% of elderly caregivers were frail. There was a significant correlation between frailty and sex, instrumental activities of daily living and cognition. Female caregivers, partially dependent individuals regarding instrumental activities of daily living and with worse cognitive state deserve a special attention from health services. Identificar a prevalência de fragilidade em cuidadores idosos inseridos em contexto de alta vulnerabilidade social e sua correlação com aspectos sociodemográficos e de saúde. Estudo descritivo, correlacional, transversal. Foram avaliados 40 cuidadores idosos utilizando-se: questionário para caracterização do cuidador, Mini Exame do Estado Mental, Índice de Katz, Escala de atividades instrumentais de vida diária de Lawton, Escala de Depressão Geriátrica e o fenótipo de fragilidade proposto por Fried. As entrevistas foram realizadas no domicílio, sendo previamente agendadas. Todos os cuidados éticos foram observados. Os dados foram analisados com apoio do pacote estatístico Stata versão 11.0. 10,0% dos cuidadores idosos eram frágeis. Houve correlação significativa entre fragilidade e: sexo, atividades instrumentais de vida diária e cognição. Conclusão: Cuidadoras do sexo feminino, indivíduos parcialmente dependentes em relação às atividades instrumentais de vida diária e com pior estado cognitivo merecem especial atenção dos serviços de saúde.

Revista de Saúde Pública: 50 years disseminating the knowledge in nutrition.

PubMed

Sichieri, Rosely; Pereira, Rosangela A

2016-12-22

This work describes and comments on articles in the area of Public Health Nutrition published in Revista de Saúde Pública (RSP - Public Health Journal) from 1967 to 2016. We searched in the PubMed database restricted to the periodical "Revista de Saúde Pública" and using terms related to key topics in the area of Public Health Nutrition. We retrieved 742 articles and, after exclusion of duplicates and articles unrelated to the subject, we analyzed 441 articles, grouped according to subject: dental caries, anemia, hypovitaminosis A, macro/micronutrients, malnutrition, nutritional assessment, overweight/obesity, food consumption, low birthweight, and breastfeeding. We observed significant increase in the number of articles published and diversification of subjects addressed over the 50 years, representing the consistent development of the scientific field of Nutrition in Brazil. Since its inception, RSP has played an important role in the dissemination of knowledge about the main nutritional issues in Brazil. RESUMO Este trabalho descreve e comenta os artigos na área de Nutrição em Saúde Pública, publicados na Revista de Saúde Pública (RSP) de 1967 a 2016. Foi realizada busca na base de dados PubMed restrita ao periódico "Revista de Saúde Pública" e utilizando termos relacionados com temáticas chaves da área de Nutrição em Saúde Pública. Foram recuperados 742 artigos e, após as exclusões dos artigos repetidos e daqueles não relacionados com a temática, foram analisados 441 artigos, agrupados segundo o tema: cárie dental, anemia, hipovitaminose A, macro/micronutrientes, desnutrição, avaliação do estado nutricional, sobrepeso/obesidade, consumo de alimentos, baixo peso ao nascer, e aleitamento materno. Observou-se incremento significativo no número de artigos publicados e a diversificação dos temas tratados ao longo destes 50 anos, retratando o consistente desenvolvimento do campo científico da Nutrição no Brasil. Desde seu início, a RSP desempenhou importante papel na divulgação do conhecimento sobre os principais agravos nutricionais no Brasil.

Prevendo a atividade solar através de redes neurais nebulosas

NASA Astrophysics Data System (ADS)

Martin, V. A. F.; Poppe, P. C. R.

2003-08-01

Atualmente, a integração de redes neurais com técnicas da Matemática Nebulosa (Fuzzy Sets), tem sido usada robustamente para fazer previsões em vários sistemas físicos. Este trabalho representa uma continuidade da contribuição apresentada anteriormente durante a XXVIIa Reunião Anual da SAB, onde exploramos a aplicação de redes neurais para previsões futuras de séries temporais. Para este, enfatizamos o uso da técnica ANFIS (Adaptative Neuro-Fuzzy Inference System), que consiste em uma rede do tipo back-propagation, onde os dados são processados em uma camada intermediária, tendo numa camada de saída, os dados numéricos. Para que a previsão seja feita com sucesso utilizando-se técnicas matemáticas adequadas, é fundamental a existência de uma série razoavelmente longa de modo que a dinâmica contida nesta possa ser melhor extraída pela rede neural. Nesse sentido, foram utilizados novamente os dados históricos das manchas do Sol (1818-2002) afim de verificar o comportamento futuro da atividade solar (Ciclos de Schawbe) a partir da técnica descrita acima. Previsões realizadas para o ciclo anterior (n.22, máximo de 158,5 em julho de 1989), bem como para o atual (n.23, máximo de 153 em setembro de 2000), apontam valores bastante coerentes com os publicados na literatura, levando em consideração, respectivamente, as barras de erros associadas: 166+/-18 e 160+/-14. Para o próximo ciclo de Schawbe (2006-2017), nossa previsão aponta o valor de 172+/-23 como máximo para o primeiro semestre de 2011 (Abril +/- 3 meses). A ANFIS acompanha de maneira satisfatória o movimento das séries estudadas durante o treinamento e durante a verificação (menor dispersão das funções de pertinência), com erro absoluto inferior a 20 por cento.

Optical studies of CdSe/HgSe and CdSe/Ag2Se core/shell nanoparticles embedded in gelatin

NASA Astrophysics Data System (ADS)

Azhniuk, Yu M.; Dzhagan, V. M.; Raevskaya, A. E.; Stroyuk, A. L.; Kuchmiy, S. Ya; Valakh, M. Ya; Zahn, D. R. T.

2008-11-01

CdSe/HgSe and CdSe/Ag2Se core-shell nanoparticles are obtained by colloidal synthesis from aqueous solutions in the presence of gelatin. Optical absorption, luminescence, and Raman spectra of the nanoparticles obtained are measured. The variation of the optical spectra of CdSe/HgSe and CdSe/Ag2Se core-shell nanoparticles with the shell thickness is discussed. Sharp non-monotonous variation of the photoluminescence spectra at low shell coverage is observed.

Structure and Properties of Modified and Charge-Compensated Chalcogenide Glasses in the Na/Ba-Ga-Ge Selenide System

NASA Astrophysics Data System (ADS)

Mao, Alvin W.

Chalcogenide glasses exhibit unique optical properties such as infrared transparency owing to the low-phonon energies, optical non-linearity, and photo-induced effects that have important consequences for a wide range of technological applications. However, to fully utilize these properties, it is necessary to better understand the atomic-scale structure and structure-property relationships in this important class of materials. Of particular interest in this regard are glasses in the stoichiometric system Na2Se/BaSe--Ga 2Se3--GeSe2 as they are isoelectronic with the well-studied, oxide glasses of the type M2O(M'O)--Al 2O3--SiO2 (M = alkali, M' = alkaline earth). This dissertation investigates the structure of stoichiometric Na 2Se/BaSe--Ga2Se3--GeSe2 and off-stoichiometric BaSe--Ga2Se3--GeSe 2+/-Se glasses using a combination of Fourier-transform Raman and solid state nuclear magnetic resonance (NMR) spectroscopies. The spectroscopic data is then compared to composition-dependent trends in physical properties such as density, optical band gap, glass transition temperature, and melt fragility to develop predictive structural models of the short- and intermediate-range order in the glass network. These models significantly improve our current understanding of the effects of modifier addition on the structure and properties of chalcogenide glasses, and thus enable a more efficient engineering of these highly functional materials for applications as solid electrolytes in batteries or as optical components in infrared photonics. In general, the underlying stoichiometric Ga2Se3--GeSe 2 network consists primarily of corner-sharing (Ga/Ge)Se4 tetrahedra, where the coordination numbers of Ga, Ge, and Se are 4, 4, and 2, respectively. Some edge-sharing exists, but this configuration is relatively unstable and its concentration tends to decrease with any deviation from the GeSe2 composition. Due to the tetrahedral coordination of Ga, the initial addition of Se-deficient Ga2Se3 to GeSe 2 results in the preferential formation of Ge-Ge bonds, which are distributed such that the clustering of ethane-like (Se3)Ge-Ge(Se3) units is avoided to the maximum extent. This behavior is entirely consistent with the continuously-alloyed structural scenario of chalcogenide glasses. However, for contents of Ga2Se3 greater than about 25--30 mol%, the avoidance of Ga-Ga and mixed Ga-Ge bonds results in the appearance of three-coordinated Se as an alternate mechanism to accommodate the Se deficiency. The addition of either Na2Se or BaSe to Ga2Se 3--GeSe2 glasses introduces an ionic bonding character to an otherwise largely covalently bonded network. As a result, the structure responds by adopting characteristics of the charge-compensated structural scenario of oxide glasses. In the stoichiometric Na2Se/BaSe--Ga 2Se3--GeSe2 glasses, the ratio of Na 2Se/BaSe:Ga2Se3 = 1 serves as a chemical threshold, where the network consists predominantly of corner-sharing (Ga/Ge)e4 tetrahedra, and the charge on the Na(Ba) cations is balanced by the GaSe4- tetrahedra. For glasses with Na 2Se/BaSe:Ga2Se3 < 1, the addition of Se-deficient Ga2Se3 induces the formation of Ge-Ge bonds. However, for glasses with Na2Se/BaSe:Ga2Se3 > 1, the addition of Na2Se/BaSe results in the formation of non-bridging Se atoms, which break up the connectivity of the glassy network. The major difference between the modifying elements Na and Ba is that the high field strength of the Ba cation induces a higher degree of chemical disorder in the glass network. This conclusion is evidenced by the presence of some Ge-Ge bonds in BaSe--Ga2Se3--GeSe2 glasses even at the chemical threshold composition of BaSe:Ga2Se3 = 1. The structural duality of the Na2Se/BaSe--Ga2Se 3--GeSe2 system is best observed in the off-stoichiometric BaSe--Ga2Se3--GeSe2+/-Se glasses. Here, the removal of Se from a stoichiometric glass with BaSe:Ga2Se 3 > 1 results in Ge-Ge bonds, while its addition in excess of stoichiometry forms Se-Se bonds. Although such behavior is consistent with the continuously-alloyed structural model, it should be contrasted with the response of the network to the removal or addition of BaSe. In the latter case especially, the network responds with the formation of non-bridging Se atoms, which is reminiscent of the charge-compensated structural scenario. The aforementioned structural conclusions are supported by trends in physical properties. Of all the properties measured, the glass transition temperature Tg responds most predictably to changes in glass structure in the sense that the removal of heteropolar (Ga/Ge)-Se bonds from the glassy network consistently results in a decrease in Tg. Indeed, Tg is observed to be maximized around chemical threshold compositions that are expected to have a fully-connected network of (Ga/Ge)Se¬4 tetrahedra. The formation of homopolar Ge-Ge bonds causes Tg to drop by ~40--80 °C, while the formation of Se-Se and/or non-bridging Se causes Tg to decrease by at least 120 °C. Trends in density reflect both the packing efficiency of the structural units within the glassy network as well as the masses of the constituent elements, and are generally observed to increase or decrease monotonically. As a result, an increase in density is associated with: 1) the removal of inefficiently packed structural units such as edge-sharing tetrahedra, 2) the formation of efficiently packed units such as three-coordinated Se atoms, 3) the removal of lighter elements like Na, and 4) the addition of heavier elements like Ba. Optical band gap is related to the bonding character within the glassy network, and tends to decrease as the bonding character becomes increasingly metallic. Therefore, a decrease in optical band gap is observed with the formation of homopolar Ge-Ge bonds when Ga2Se3 is added to GeSe2. However, the stoichiometric BaSe--Ga2Se 3--GeSe2 glasses show an anomaly in this regard because optical band gap decreases with the addition of BaSe, and consequently the removal of Ge-Ge bonds. This observation was ascribed instead to the formation of Ba-Se bonds, which are associated with a lower bandgap compared to the (Ga/Ge)-Se bonds that they replace. Finally, there is no straightforward structural explanation for trends in fragility, because it is related to the number of structural configurations dynamically available to the supercooled liquid. In the binary Ga2Se3--GeSe2 glasses, the fragility tends to increase with the formation of homopolar Ge-Ge bonds, which is consistent with other chalcogenide systems in which fragility increases with the removal of heteropolar bonds within corner-sharing tetrahedra and pyramids. In the stoichiometric BaSe--Ga2Se3--GeSe2 glasses on the other hand, a shift in trend near the compositions where BaSe:Ga 2Se3 = 1 coincides with a structural shift between the formation of Ge-Ge bonds and Se-Se/non-bridging Se.

Selenium Assimilation and Volatilization from Selenocyanate-Treated Indian Mustard and Muskgrass1

PubMed Central

de Souza, Mark P.; Pickering, Ingrid J.; Walla, Michael; Terry, Norman

2002-01-01

Selenocyanate (SeCN−) is a major contaminant in the effluents from some oil refineries, power plants, and in mine drainage water. In this study, we determined the potential of Indian mustard (Brassica juncea) and muskgrass (a macroalga, Chara canescens) for SeCN− phytoremediation in upland and wetland situations, respectively. The tolerance of Indian mustard to toxic levels of SeCN− was similar to or higher than other toxic forms of Se. Indian mustard treated with 20 μm SeCN− removed 30% (w/v) of the Se supplied in 5 d, accumulating 554 and 86 μg of Se g−1 dry weight in roots and shoots, respectively. Under similar conditions, muskgrass removed approximately 9% (w/v) of the Se supplied as SeCN− and accumulated 27 μg of Se g−1 dry weight. A biochemical pathway for SeCN− degradation was proposed for Indian mustard. Indian mustard and muskgrass efficiently degraded SeCN− as none of the Se accumulated by either organism remained in this form. Indian mustard accumulated predominantly organic Se, whereas muskgrass contained Se mainly as selenite and organic Se forms. Indian mustard produced volatile Se from SeCN− in the form of less toxic dimethylselenide. Se volatilization by Indian mustard accounted for only 0.7% (w/v) of the SeCN− removed, likely because the biochemical steps in the production of dimethylselenide from organic Se were rate limiting. Indian mustard is promising for the phytoremediation of SeCN−-contaminated soil and water because of its remarkable abilities to phytoextract SeCN− and degrade all the accumulated SeCN− to other Se forms. PMID:11842165

Exploration work function and optical properties of monolayer SnSe allotropes

NASA Astrophysics Data System (ADS)

Cui, Zhen; Wang, Xia; Ding, Yingchun; Li, Meiqin

2018-02-01

The work function and optical properties are investigated with density functional theory for three monolayer SnSe allotropes. The calculated results indicate that the α-SnSe, δ-SnSe, ε-SnSe are semiconductor with the band gaps of 0.90, 1.25, and 1.50 eV, respectively. Meanwhile, the work function of δ-SnSe is lower than α-SnSe and ε-SnSe, which indicates that the δ-SnSe can be prepared of photoemission and field emission nanodevices. More importantly, the α-SnSe, δ-SnSe, ε-SnSe with the large static dielectric constants are 4.22, 5.48, and 3.61, which demonstrate that the three monolayer SnSe allotropes can be fabricated the capacitor. In addition, the static refractive index of δ-SnSe is larger than α-SnSe and ε-SnSe. The different optical properties with three monolayer SnSe allotropes reveal that the allotropes can regulate the properties of the materials. Moreover, our researched results show that the three monolayer SnSe allotropes are sufficient for fabrication of optoelectronic nanodevices.

Thermoelectric properties of SrTiO3 nano-particles dispersed indium selenide bulk composites

NASA Astrophysics Data System (ADS)

Lee, Min Ho; Rhyee, Jong-Soo; Vaseem, Mohammad; Hahn, Yoon-Bong; Park, Su-Dong; Jin Kim, Hee; Kim, Sung-Jin; Lee, Hyeung Jin; Kim, Chilsung

2013-06-01

We investigated the thermoelectric properties of the InSe, InSe/In4Se3 composite, and SrTiO3 (STO) nano-particles dispersed InSe/In4Se3 bulk composites. The electrical conductivity of the InSe/In4Se3 composite with self-assembled phase separation is significantly increased compared with those of InSe and In4Se3-δ implying the enhancement of surface conductivity between grain boundaries. The thermal conductivity of InSe/In4Se3 composite is decreased compared to those of InSe. When the STO nano-particle dispersion was employed in the InSe/In4Se3 composite, a coherent interface was observed between nano-particle precipitates and the InSe bulk matrix with a reduction of the thermal conductivity.

PSYCHOLOGICAL PROFILE OF PATIENTS ELIGIBLE FOR BARIATRIC SURGERY.

PubMed

Ribeiro, Graziela Aparecida Nogueira de Almeida; Giampietro, Helenice Brizolla; Belarmino, Lídia Barbieri; Salgado-Júnior, Wilson

The psychologist who works in bariatric surgery has a role to receive, evaluate, prepare and educate the patient who will undergo the surgical procedure. Psychological evaluation becomes important in so far as allows us to obtain data on personal and familiar history and allow tracing of possible psychopathology. To collect data on psychological evaluations of patients in a bariatric surgery service of a public hospital in order to describe the psychological profile of patients in this service. Data were collected from 827 patients between 2001 and 2015, using data from an interview, Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI) and Binge Eating Scale (BES). The mean age of patients before surgery was 39 years+/- 10, the mean BMI was 51 kg/m²+7, and most patients (81%) were female. The average score on the BDI was 14.8+8 and women had significantly higher scores than men. On the BAI the average score was 11+8 and on the ECAP was 14+8, both with no difference between groups. Psychosocial characteristics of the patients points to the significant presence of indicators of depression, with low levels of anxiety and binge eating. O psicólogo que atua na área da cirurgia bariátrica tem papel de acolher, avaliar, preparar e conscientizar o paciente que vai ser submetido ao procedimento cirúrgico. A avaliação psicológica reveste-se de importância na medida em que obtém dados sobre história pessoal e familiar, além do rastreio de possíveis alterações psicopatológicas. Analisar as avaliações psicológicas dos pacientes de um serviço de cirurgia bariátrica de um hospital público, buscando traçar o perfil psicológico dos pacientes deste serviço. Foram coletados dados de 827 pacientes entre 2001 e 2015, utilizando-se dados de uma entrevista, Inventário Beck de Depressão (BDI), Inventário Beck de Ansiedade (BAI) e Escala de Compulsão Alimentar Periódica (ECAP). A idade média dos pacientes antes da operação foi 39 anos+10 e o IMC médio foi 51 kg/m²+7, sendo a maioria (81%) do gênero feminino. A pontuação média no BDI foi 14,8+8 e as mulheres tiveram pontuação significativamente maior que os homens. No BAI a pontuação média foi 11+ 8 e no ECAP 14+ 8, ambos sem diferença entre os grupos. A caracterização psicossocial dos pacientes avaliados aponta para a presença significativa de indicadores de depressão, com baixos níveis de ansiedade e de compulsão alimentar.

Selenium speciation in wheat grain varies in the presence of nitrogen and sulphur fertilisers.

PubMed

Duncan, Elliott G; Maher, William A; Jagtap, Rajani; Krikowa, Frank; Roper, Margaret M; O'Sullivan, Cathryn A

2017-08-01

This study investigated whether selenium species in wheat grains could be altered by exposure to different combinations of nitrogen (N) and sulphur (S) fertilisers in an agronomic biofortification experiment. Four Australian wheat cultivars (Mace, Janz, Emu Rock and Magenta) were grown in a glasshouse experiment and exposed to 3 mg Se kg -1 soil as selenate (Se VI ). Plants were also exposed to 60 mg N kg -1 soil as urea and 20 mg S kg -1 soil as gypsum in a factorial design (N + S + Se; N + Se; S + Se; Se only). Plants were grown to maturity with grain analysed for total Se concentrations via ICP-MS and Se species determined via HPLC-ICP-MS. Grain Se concentrations ranged from 22 to 70 µg Se g -1 grain (dry mass). Selenomethionine (SeMet), Se-methylselenocystine (MeSeCys), selenohomolanthionine (SeHLan), plus a large concentration of uncharacterised Se species were found in the extracts from grains. SeMet was the major Se species identified accounting for between 9 and 24 µg Se g -1 grain. Exposure to different N and S fertiliser combinations altered the SeMet content of Mace, Janz and Emu Rock grain, but not that of Magenta. MeSeCys and SeHLan were found in far lower concentrations (<4 µg Se g -1 grain). A large component of the total grain Se was uncharacterisable (>30 % of total grain Se) in all samples. When N fertiliser was applied (with or without S), the proportion of uncharacterisable Se increased between 60 and 70 % of the total grain Se. The data presented here indicate that it is possible to alter the content of individual Se species in wheat grains via biofortification combined with manipulation of N and S fertiliser regimes. This has potential significance in alleviating or combating both Se deficiency and Se toxicity effects in humans.

Protective Effects of Cannabidiol against Seizures and Neuronal Death in a Rat Model of Mesial Temporal Lobe Epilepsy.

PubMed

Do Val-da Silva, Raquel A; Peixoto-Santos, Jose E; Kandratavicius, Ludmyla; De Ross, Jana B; Esteves, Ingrid; De Martinis, Bruno S; Alves, Marcela N R; Scandiuzzi, Renata C; Hallak, Jaime E C; Zuardi, Antonio W; Crippa, Jose A; Leite, Joao P

2017-01-01

The present study reports the behavioral, electrophysiological, and neuropathological effects of cannabidiol (CBD), a major non-psychotropic constituent of Cannabis sativa , in the intrahippocampal pilocarpine-induced status epilepticus (SE) rat model. CBD was administered before pilocarpine-induced SE (group SE+CBDp) or before and after SE (group SE+CBDt), and compared to rats submitted only to SE (SE group), CBD, or vehicle (VH group). Groups were evaluated during SE (behavioral and electrophysiological analysis), as well as at days one and three post-SE (exploratory activity, electrophysiological analysis, neuron density, and neuron degeneration). Compared to SE group, SE+CBD groups (SE+CBDp and SE+CBDt) had increased SE latency, diminished SE severity, increased contralateral afterdischarge latency and decreased relative powers in delta (0.5-4 Hz) and theta (4-10 Hz) bands. Only SE+CBDp had increased vertical exploratory activity 1-day post SE and decreased contralateral relative power in delta 3 days after SE, when compared to SE group. SE+CBD groups also showed decreased neurodegeneration in the hilus and CA3, and higher neuron density in granule cell layer, hilus, CA3, and CA1, when compared to SE group. Our findings demonstrate anticonvulsant and neuroprotective effects of CBD preventive treatment in the intrahippocampal pilocarpine epilepsy model, either as single or multiple administrations, reinforcing the potential role of CBD in the treatment of epileptic disorders.

Effect of selenium-enriched organic material amendment on selenium fraction transformation and bioavailability in soil.

PubMed

Wang, Dan; Dinh, Quang Toan; Anh Thu, Tran Thi; Zhou, Fei; Yang, Wenxiao; Wang, Mengke; Song, Weiwei; Liang, Dongli

2018-05-01

To exploit the plant byproducts from selenium (Se) biofortification and reduce environmental risk of inorganic Se fertilizer, pot experiment was conducted in this study. The effects of Se-enriched wheat (Triticum aestivum L.) straw (WS + Se) and pak choi (Brassica chinensis L.) (P + Se) amendment on organo-selenium speciation transformation in soil and its bioavailability was evaluated by pak choi uptake. The Se contents of the cultivated pak choi in treatments amended with the same amount of Se-enriched wheat straw and pak choi were 1.7 and 9.7 times in the shoots and 2.3 and 6.3 times in the roots compared with control treatment. Soil respiration rate was significantly increased after all organic material amendment in soil (p < 0.05), which accelerated the mineralization of organic materials and thus resulted in soluble Se (SOL-Se), exchangeable Se (EX-Se), and fulvic acid-bound Se (FA-Se) fraction increasing by 25.2-29.2%, 9-13.8%, and 4.92-8.28%, respectively. In addition, both Pearson correlation and cluster analysis showed that EX-Se and FA-Se were better indicators for soil Se availability in organic material amendment soils. The Marquardt-Levenberg Model well described the dynamic kinetics of FA-Se content after Se-enriched organic material amendment in soil mainly because of the mineralization of organic carbon and organo-selenium. The utilization of Se in P + Se treatment was significantly higher than those in WS + Se treatment because of the different mineralization rates and the amount of FA-Se in soil. Se-enriched organic materials amendment can not only increase the availability of selenium in soil but also avoid the waste of valuable Se source. Copyright © 2018 Elsevier Ltd. All rights reserved.

Selenium species-dependent toxicity, bioavailability and metabolic transformations in Caenorhabditis elegans.

PubMed

Rohn, Isabelle; Marschall, Talke Anu; Kroepfl, Nina; Jensen, Kenneth Bendix; Aschner, Michael; Tuck, Simon; Kuehnelt, Doris; Schwerdtle, Tanja; Bornhorst, Julia

2018-05-17

The essential micronutrient selenium (Se) is required for various systemic functions, but its beneficial range is narrow and overexposure may result in adverse health effects. Additionally, the chemical form of the ingested selenium contributes crucially to its health effects. While small Se species play a major role in Se metabolism, their toxicological effects, bioavailability and metabolic transformations following elevated uptake are poorly understood. Utilizing the tractable invertebrate Caenorhabditis elegans allowed for an alternative approach to study species-specific characteristics of organic and inorganic Se forms in vivo, revealing remarkable species-dependent differences in the toxicity and bioavailability of selenite, selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys). An inverse relationship was found between toxicity and bioavailability of the Se species, with the organic species displaying a higher bioavailability than the inorganic form, yet being less toxic. Quantitative Se speciation analysis with HPLC/mass spectrometry revealed a partial metabolism of SeMet and MeSeCys. In SeMet exposed worms, identified metabolites were Se-adenosylselenomethionine (AdoSeMet) and Se-adenosylselenohomocysteine (AdoSeHcy), while worms exposed to MeSeCys produced Se-methylselenoglutathione (MeSeGSH) and γ-glutamyl-MeSeCys (γ-Glu-MeSeCys). Moreover, the possible role of the sole selenoprotein in the nematode, thioredoxin reductase-1 (TrxR-1), was studied comparing wildtype and trxr-1 deletion mutants. Although a lower basal Se level was detected in trxr-1 mutants, Se toxicity and bioavailability following acute exposure was indistinguishable from wildtype worms. Altogether, the current study demonstrates the suitability of C. elegans as a model for Se species dependent toxicity and metabolism, while further research is needed to elucidate TrxR-1 function in the nematode.

Neuroimaging, Genetics, and Clinical Data Sharing in Python Using the CubicWeb Framework

PubMed Central

Grigis, Antoine; Goyard, David; Cherbonnier, Robin; Gareau, Thomas; Papadopoulos Orfanos, Dimitri; Chauvat, Nicolas; Di Mascio, Adrien; Schumann, Gunter; Spooren, Will; Murphy, Declan; Frouin, Vincent

2017-01-01

In neurosciences or psychiatry, the emergence of large multi-center population imaging studies raises numerous technological challenges. From distributed data collection, across different institutions and countries, to final data publication service, one must handle the massive, heterogeneous, and complex data from genetics, imaging, demographics, or clinical scores. These data must be both efficiently obtained and downloadable. We present a Python solution, based on the CubicWeb open-source semantic framework, aimed at building population imaging study repositories. In addition, we focus on the tools developed around this framework to overcome the challenges associated with data sharing and collaborative requirements. We describe a set of three highly adaptive web services that transform the CubicWeb framework into a (1) multi-center upload platform, (2) collaborative quality assessment platform, and (3) publication platform endowed with massive-download capabilities. Two major European projects, IMAGEN and EU-AIMS, are currently supported by the described framework. We also present a Python package that enables end users to remotely query neuroimaging, genetics, and clinical data from scripts. PMID:28360851

Neuroimaging, Genetics, and Clinical Data Sharing in Python Using the CubicWeb Framework.

PubMed

Grigis, Antoine; Goyard, David; Cherbonnier, Robin; Gareau, Thomas; Papadopoulos Orfanos, Dimitri; Chauvat, Nicolas; Di Mascio, Adrien; Schumann, Gunter; Spooren, Will; Murphy, Declan; Frouin, Vincent

2017-01-01

In neurosciences or psychiatry, the emergence of large multi-center population imaging studies raises numerous technological challenges. From distributed data collection, across different institutions and countries, to final data publication service, one must handle the massive, heterogeneous, and complex data from genetics, imaging, demographics, or clinical scores. These data must be both efficiently obtained and downloadable. We present a Python solution, based on the CubicWeb open-source semantic framework, aimed at building population imaging study repositories. In addition, we focus on the tools developed around this framework to overcome the challenges associated with data sharing and collaborative requirements. We describe a set of three highly adaptive web services that transform the CubicWeb framework into a (1) multi-center upload platform, (2) collaborative quality assessment platform, and (3) publication platform endowed with massive-download capabilities. Two major European projects, IMAGEN and EU-AIMS, are currently supported by the described framework. We also present a Python package that enables end users to remotely query neuroimaging, genetics, and clinical data from scripts.

Supplementation of organic and inorganic selenium to diets using grains grown in various regions of the United States with differing natural Se concentrations and fed to grower-finisher swine.

PubMed

Mahan, D C; Azain, M; Crenshaw, T D; Cromwell, G L; Dove, C R; Kim, S W; Lindemann, M D; Miller, P S; Pettigrew, J E; Stein, H H; van Heugten, E

2014-11-01

Grains grown in various regions of the United States vary in their innate or natural Se contents. A regional study evaluated the effects of adding inorganic Se (sodium selenite) or organic Se (Se yeast) to diets with differing innate Se contents. A 2 × 2 + 1 factorial experiment evaluating 2 Se sources (organic or inorganic) at 2 Se levels (0.15 or 0.30 mg/kg) in 18 total replicates (n = 360 total pigs). A basal diet was fed without supplemental Se and served as the negative (basal) control. The study was conducted as a randomized complete block design in 9 states (Georgia, Illinois, Kentucky, Nebraska, North Carolina, Ohio, South Dakota, Texas, and Wisconsin) with each station conducting 2 replicates. Pigs were fed from 25 to approximately 115 kg BW. Similar dietary formulations were used at each station, incorporating a common source of trace mineral and Se premixes. Three pigs per treatment in 16 replicates (n = 240) were bled at 55, 85, and 115 kg BW and serum Se and glutathione peroxidase (GSH-Px) activities were determined. Three pigs (n = 260) from each treatment pen were killed at 115 kg BW and issues (liver, loin, and hair) were analyzed for Se. The corn Se content from the various states ranged from 0.026 to 0.283 mg Se/kg while the soybean meal Se content ranged from 0.086 to 0.798 mg Se/kg. Tissue and serum Se concentrations were greater (P < 0.01) when supplemental organic Se was fed, whereas serum GSH-Px was greater (P < 0.01) as Se level increased. There were linear increases (P < 0.01) in loin and quadratic increases (P < 0.01) in liver and hair Se concentrations as dietary Se level increased within each state. There was a source × level interaction (P < 0.01) for each tissue resulting in a greater increase when organic Se was fed. Serum Se and GSH-Px activity increased (P < 0.01) when both Se sources were fed and plateaued at each state at 0.15 mg Se/kg. There was a high and significant correlation between each tissue Se, serum Se, and GSH-Px activity to dietary Se level indicating that those states having greater grain natural Se contents also had greater tissue Se concentrations. These results indicate that a large difference in corn and soybean meal Se concentrations exists between states, that the addition of organic or inorganic Se to these grains increased tissue and serum Se in each state, and that organic Se was incorporated at greater concentrations in the loin, liver, and hair tissues of grower-finisher pigs than inorganic Se.

Fractionation of selenium isotopes during bacterial respiratory reduction of selenium oxyanions

USGS Publications Warehouse

Herbel, M.J.; Johnson, T.M.; Oremland, R.S.; Bullen, T.D.

2000-01-01

Reduction of selenium oxyanions by microorganisms is an important process in the biogeochemical cycling of selenium. Numerous bacteria can reduce Se oxyanions, which are used as electron acceptors during the oxidation of organic matter in anoxic environments. In this study, we used a double spike (82Se and 74Se) thermal ionization mass spectrometry technique to quantify the isotopic fractionation achieved by three different species of anaerobic bacteria capable of accomplishing growth by respiratory reduction of selenate [SeO42- or Se(VI)] or selenite [SeO32- or Se(IV)] to Se(IV) or elemental selenium [Se(0)] coupled with the oxidation of lactate. Isotopic discrimination in these closed system experiments was evaluated by Rayleigh fractionation equations and numerical models. Growing cultures of Bacillus selenitireducens, a haloalkaliphile capable of growth using Se(IV) as an electron acceptor, induced a 80Se/76Se fractionation of -8.0 ?? 0.4??? (instantaneous ?? value) during reduction of Se(IV) to Se(0). With Bacillus arsenicoselenatis, a haloalkaliphile capable of growth using Se(VI) as an electron acceptor, fractionations of -5.0 ?? 0.5??? and -6.0 ?? 1.0??? were observed for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(0), respectively. In growing cultures of Sulfurospirillum barnesii, a freshwater species capable of growth using Se(VI), fractionation was small initially, but near the end of the log growth phase, it increased to -4.0 ?? 1.0??? and -8.4 ?? 0.4??? for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(O), respectively. Washed cell suspensions of S. barnesii induced fractionations of -1.1 ?? 0.4??? during Se(VI) reduction, and -9.1 ?? 0.5% for Se(IV) reduction, with some evidence for smaller values (e.g., -1.7???) in the earliest-formed Se(0) results. These results demonstrate that dissimilatory reduction of selenate or selenite induces significant isotopic fractionation, and suggest that significant Se isotope ratio variation will be found in nature. Copyright (C) 2000 Elsevier Science Ltd.

Reparo de aneurisma de artéria ilíaca roto em criança

PubMed Central

Hoshiko, Fernando Massaru; Zampieri, Elisa Helena Subtil; Dalio, Marcelo Bellini; Dezotti, Nei Rodrigues Alves; Joviliano, Edwaldo Edner

2017-01-01

Resumo Relatamos o caso de uma menina de 12 anos que deu entrada na unidade de emergência com quadro de abdome agudo hemorrágico, massa abdominal pulsátil e instabilidade hemodinâmica. Confirmado o diagnóstico de aneurisma roto de artéria ilíaca direita, foi realizada correção cirúrgica de emergência por reparo aberto com reconstrução extra-anatômica, utilizando enxerto sintético de fino calibre, compatível com a anatomia. O tratamento foi bem-sucedido e a criança apresentou evolução favorável em curto prazo.

Assessment of the anticancer compounds Se-methylselenocysteine and glucosinolates in Se-biofortified broccoli (Brassica oleracea L. var. italica) sprouts and florets.

PubMed

Ávila, Fabricio William; Faquin, Valdemar; Yang, Yong; Ramos, Silvio Junio; Guilherme, Luiz Roberto G; Thannhauser, Theodore W; Li, Li

2013-07-03

Broccoli (Brassica oleracea L. var. italica) is a rich source of chemopreventive compounds. Here, we evaluated and compared the effect of selenium (Se) treatment on the accumulation of anticancer compounds Se-methylselenocysteine (SeMSCys) and glucosinolates in broccoli sprouts and florets. Total Se and SeMSCys content in sprouts increased concomitantly with increasing Se doses. Selenate was superior to selenite in inducing total Se accumulation, but selenite is equally effective as selenate in promoting SeMSCys synthesis in sprouts. Increasing sulfur doses reduced total Se and SeMSCys content in sprouts treated with selenate, but not in those with selenite. Examination of five broccoli cultivars reveals that sprouts generally have better fractional ability than florets to convert inorganic Se into SeMSCys. Distinctive glucosinolate profiles between sprouts and florets were observed, and sprouts contained approximately 6-fold more glucoraphanin than florets. In contrast to florets, glucosinolate content was not affected by Se treatment in sprouts. Thus, Se-enriched broccoli sprouts are excellent for simultaneous accumulation of chemopreventive compounds SeMSCys and glucoraphanin.

Selenium accumulation in plants--phytotechnological applications and ecological implications.

PubMed

Valdez Barillas, José Rodolfo; Quinn, Colin F; Pilon-Smits, Elizabeth A H

2011-01-01

Selenium (Se) is an essential trace element for many organisms including humans, yet toxic at higher levels. Both Se deficiency and toxicity are problems worldwide. Since plants readily accumulate and volatilize Se, they may be used both as a source of dietary Se and for removing excess Se from the environment. Plant species differ in their capacity to metabolize and accumulate Se, from non-Se accumulators (< 100 mg Se/kg DW), to Se-accumulators (100-1000 mg Se/kg DW) to Se hyperaccumulators (> 1,000 mg Se/kg DW). Here we review plant mechanisms of Se metabolism in these various plant types. We also summarize results from genetic engineering that have led to enhanced plant Se accumulation, volatilization, and/or tolerance, including field studies. Before using Se-accumulating plants at a large scale we need to evaluate the ecological implications. Research so far indicates that plant Se accumulation significantly affects the plant's ecological interactions below and above ground. Selenium canprotect plants from fungal pathogens and from a variety of invertebrate and vertebrate herbivores, due to both deterrence and toxicity. However, specialist (Se-tolerant herbivores), detritivores and endophytes appear to utilize Se hyperaccumulator plants as a resource. These findings are relevant for managing phytoremediation of Se and similar elements.

Characterization of a selenium-tolerant rhizosphere strain from a novel Se-hyperaccumulating plant Cardamine hupingshanesis.

PubMed

Tong, Xinzhao; Yuan, Linxi; Luo, Lei; Yin, Xuebin

2014-01-01

A novel selenium- (Se-) hyperaccumulating plant, Cardamine hupingshanesis, accumulating Se as a form of SeCys2, was discovered in Enshi, Hubei, China, which could not be explained by present selenocysteine methyltransferase (SMT) theory. However, it is interesting to investigate if rhizosphere bacteria play some roles during SeCys2 accumulation. Here, one Se-tolerant rhizosphere strain, Microbacterium oxydans, was isolated from C. hupingshanesis. Phylogenetic analysis and 16S rRNA gene sequences determined the strain as a kind of Gram positive bacillus and belonged to the family Brevibacterium frigoritolerans. Furthermore, Se tolerance test indicated the strain could grow in extreme high Se level of 15.0 mg Se L(-1). When exposed to 1.5 mg Se L(-1), SeCys2 was the predominant Se species in the bacteria, consistent with the Se species in C. hupingshanesis. This coincidence might reveal that this strain played some positive effect in SeCys2 accumulation of C. hupingshanesis. Moreover, when exposed to 1.5 mg Se L(-1) or 15.0 mg Se L(-1), As absorption diminished in the logarithmic phase. In contrast, As absorption increased when exposed to 7.5 mg Se L(-1), indicating As metabolism processes could be affected by Se on this strain. The present study provided a sight on the role of rhizosphere bacteria during Se accumulation for Se-hyperaccumulating plant.

Protective Effects of Cannabidiol against Seizures and Neuronal Death in a Rat Model of Mesial Temporal Lobe Epilepsy

PubMed Central

Do Val-da Silva, Raquel A.; Peixoto-Santos, Jose E.; Kandratavicius, Ludmyla; De Ross, Jana B.; Esteves, Ingrid; De Martinis, Bruno S.; Alves, Marcela N. R.; Scandiuzzi, Renata C.; Hallak, Jaime E. C.; Zuardi, Antonio W.; Crippa, Jose A.; Leite, Joao P.

2017-01-01

The present study reports the behavioral, electrophysiological, and neuropathological effects of cannabidiol (CBD), a major non-psychotropic constituent of Cannabis sativa, in the intrahippocampal pilocarpine-induced status epilepticus (SE) rat model. CBD was administered before pilocarpine-induced SE (group SE+CBDp) or before and after SE (group SE+CBDt), and compared to rats submitted only to SE (SE group), CBD, or vehicle (VH group). Groups were evaluated during SE (behavioral and electrophysiological analysis), as well as at days one and three post-SE (exploratory activity, electrophysiological analysis, neuron density, and neuron degeneration). Compared to SE group, SE+CBD groups (SE+CBDp and SE+CBDt) had increased SE latency, diminished SE severity, increased contralateral afterdischarge latency and decreased relative powers in delta (0.5–4 Hz) and theta (4–10 Hz) bands. Only SE+CBDp had increased vertical exploratory activity 1-day post SE and decreased contralateral relative power in delta 3 days after SE, when compared to SE group. SE+CBD groups also showed decreased neurodegeneration in the hilus and CA3, and higher neuron density in granule cell layer, hilus, CA3, and CA1, when compared to SE group. Our findings demonstrate anticonvulsant and neuroprotective effects of CBD preventive treatment in the intrahippocampal pilocarpine epilepsy model, either as single or multiple administrations, reinforcing the potential role of CBD in the treatment of epileptic disorders. PMID:28367124

Endogenous molecules released by haemocytes receiving Sargassum oligocystum extract lead to downstream activation and synergize innate immunity in white shrimp Litopenaeus vannamei.

PubMed

Shi, Yin-Ze; Chen, Jiann-Chu; Chen, Yu-Yuan; Kuo, Yi-Hsuan; Li, Hui-Fang

2018-05-01

White shrimp Litopenaeus vannamei haemocytes receiving immunostimulating Sargassum oligocystum extract (SE) caused necrosis in haemocyte cells, which released endogenous EM-SE molecules. This study examined the immune response of white shrimp L. vannamei receiving SE and EM-SE in vitro and in vivo. Shrimp haemocytes receiving SE exhibited degranulation, changes in cell size and cell viability, necrosis and a release of EM-SE. Shrimp haemocytes receiving SE, EM-SE, and the SE + EM-SE mixture (SE + EM-SE) increased their phenoloxidase (PO) activity which was significantly higher in shrimp haemocytes receiving the SE + EM-SE mixture. Furthermore, shrimp haemocytes receiving EM-SE showed degranulation and changes in cell size and cell viability. Shrimp receiving SE, EM-SE, and SE + EM-SE all increased their immune parameters, phagocytic activity, clearance efficiency and resistance to Vibrio alginolyticus, being significantly higher in shrimp receiving SE + EM-SE. Meanwhile, the recombinant lipopolysaccharide- and β-1,3-glucan binding protein of L. vannamei (rLvLGBP) was bound to SE, EM-SE, and SE + EM-SE. We conclude that in shrimp haemocytes receiving a non-self molecule, SE in dying cells released EM-SE which led to downstream activation and synergization of the immune response. This study demonstrated that the innate immunity of shrimp was elicited and enhanced by a mixture of endogenous molecules and exogenous substances (or immunostimulants). Copyright © 2018 Elsevier Ltd. All rights reserved.

Efficacy of selenium from hydroponically produced selenium-enriched kale sprout (Brassica oleracea var. alboglabra L.) in broilers.

PubMed

Chantiratikul, Anut; Pakmaruek, Pornpan; Chinrasri, Orawan; Aengwanich, Worapol; Chookhampaeng, Sumalee; Maneetong, Sarunya; Chantiratikul, Piyanete

2015-05-01

An experiment was conducted to determine the efficacy of Se from hydroponically produced Se-enriched kale sprout (HPSeKS) on performance, carcass characteristics, tissue Se concentration, and physiological responses of broilers in comparison to that of Se from Se-enriched yeast and sodium selenite. Three hundred and sixty male broilers, 10 days of age, were assigned to 6 groups, 4 replicates of 15 broilers each, according to the completely randomized design. The dietary treatments were the following: T1: control diet; T2: control diet plus 0.3 mg Se/kg from sodium selenite; T3: control diet plus 0.3 mg Se/kg from Se-enriched yeast; and T4, T5, and T6: control diet plus 0.3, 1.0, and 2.0 mg Se/kg from HPSeKS, respectively. The results found that dietary Se supplementation did not (p > 0.05) alter performance and carcass characteristics of broilers. Se supplementation increased (p < 0.05) Se concentrations in the liver and kidney of broilers. Heart tissue Se concentration of broilers fed Se from sodium selenite was lower (p < 0.05) than that of broilers fed Se from HPSeKS and Se-enriched yeast. Selenium from HPSeKS increased higher (p < 0.05) GSH-Px activity when compared to Se from sodium selenite and Se-enriched yeast. The results indicated that the efficacy of Se from HPSeKS was comparable in increasing tissue Se concentration, but higher in improving GSH-Px activity in Rbc when compared to those of Se from Se-enriched yeast.

Productivity and selenium concentrations in egg and tissue of laying quails fed selenium from hydroponically produced selenium-enriched kale sprout (Brassica oleracea var. alboglabra L.).

PubMed

Chinrasri, Orawan; Chantiratikul, Piyanete; Maneetong, Sarunya; Chookhampaeng, Sumalee; Chantiratikul, Anut

2013-12-01

This study aimed to determine the effectiveness of Se from hydroponically produced Se-enriched kale sprout (HPSeKS) on productive performance, egg quality, and Se concentrations in egg and tissue of laying quails. Two-hundred quails, 63 days of age, were divided into four groups. Each group consisted of five replicates and each replicate had ten birds, according to a completely randomized design. The experiment lasted for 6 weeks. The dietary treatments were T1 (control diet), T2 (control diet plus 0.2 mg Se/kg from sodium selenite), T3 (control diet plus 0.2 mg Se/kg from Se-enriched yeast), T4 (control diet plus 0.2 mg Se/kg from HPSeKS). The findings revealed that productive performance and egg quality of quails were not altered (p > 0.05) by Se sources. Whole egg Se concentrations of quails fed Se from HPSeKS and Se-enriched yeast were higher (p < 0.05) than that of quails fed the control diet. Breast muscle Se concentrations in quails fed Se from HPSeKS were higher (p < 0.05) than that of quails fed Se from sodium selenite and Se-enriched yeast. Heart tissue Se concentrations of quails fed Se from Se-enriched yeast and HPSeKS were similar (p > 0.05), but higher (p < 0.05) than that of quails fed Se from sodium selenite. The results reveal that Se from HPSeKS did not change the performance and egg quality of quails. The effectiveness of Se from HPSeKS was comparable to that of Se-enriched yeast, which was higher than that of Se from sodium selenite.

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prakash, Jai; Mesbah, Adel; ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex

2015-11-15

The compound Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} has been synthesized by solid-state methods at 1173 K. Its crystal structure features one-dimensional chains of {sup 1}{sub ∞}[Th(Se){sub 3}(Se{sub 2}){sub 2}{sup 6−}] separated by Ba{sup 2+} cations. Each Th atom in these chains is coordinated to two Se–Se single-bonded pairs and four Se atoms to give rise to a pseudooctahedral geometry around Th. The Th–Se distances are consistent with Th{sup 4+} and hence charge balance of Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} is achieved as 3×Ba{sup 2+}, 1×Th{sup 4+}, 3×Se{sup 2−}, and 2×Se{sub 2}{sup 2−}. From optical measurements the band gap of Ba{submore » 3}ThSe{sub 3}(Se{sub 2}){sub 2} is 1.96(2) eV. DFT calculations indicate that the compound is a semiconductor. - Graphical abstract: Local coordination environment of Th atoms in the Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} structure. - Highlights: • Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} has been synthesized by solid-state methods at 1173 K. • The structure features chains of {sup 1}{sub ∞}[Th(Se){sub 3}(Se{sub 2}){sub 2}{sup 6−}] separated by Ba{sup 2+} cations. • Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} is a semiconductor with a band gap of 1.96(2) eV.« less

Effect of feed selenium supplementation on milk selenium distribution and mozzarella quality.

PubMed

Liu, H Y; Zhu, W Z; Lu, B Y; Wei, Z H; Ren, D X

2015-12-01

In the present study, the effect of feed Se supplementation on the Se content of raw milk and mozzarella cheese as well as the effect on cheese quality and functionality were determined. The Se milk was produced by supplying dairy cow feed with Se yeast (0.3mg of Se/kg of dry matter), resulting in a Se concentration in milk of 35.81μg/L. The fat, casein, and whey protein of Se milk were separated by ultracentrifugation, and the Se content was determined by atomic absorption spectroscopy. The Se distribution in different milk fractions of fat, casein, and whey protein were 9.82, 45.56, and 44.62%, respectively. The Se mozzarella cheese was made by Se milk, and the composition and texture of Se cheese did not significantly differ from that of the control. However, the functional properties (meltability, flowability, and stretchability) of the Se cheese were better after 8 wk of storage. Moreover, the pH and water activity were lower in Se cheese, which decreased the total plate count. The Se content in mozzarella cheese was 4 fold higher than that in milk, and Se was found in the whey, hot water, and brine collected during cheesemaking. Organic and inorganic Se was found in the Se cheese after 8 wk of storage, and most Se peptides detected after storage were Se-Met and Se-Cys. The results of this study show that feed Se supplementation can improve the Se content of milk and cheese without affecting mozzarella cheese quality. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Selenium speciation and partitioning within Burkholderia cepacia biofilms formed on α-Al 2O 3 surfaces

NASA Astrophysics Data System (ADS)

Templeton, Alexis S.; Trainor, Thomas P.; Spormann, Alfred M.; Brown, Gordon E.

2003-10-01

The distribution and speciation of Se within aerobic Burkholderia cepacia biofilms formed on α-Al 2O 3 (1-102) surfaces have been examined using grazing-angle X-ray spectroscopic techniques. We present quantitative information on the partitioning of 10 -6 M to 10 -3 M selenate and selenite between the biofilms and underlying alumina surfaces derived from long-period X-ray standing wave (XSW) data. Changes in the Se partitioning behavior over time are correlated with microbially induced reduction of Se(VI) and Se(IV) to Se(0), as observed from X-ray absorption near edge structure (XANES) spectroscopy. Selenite preferentially binds to the alumina surfaces, particularly at low [Se], and is increasingly partitioned into the biofilms at higher [Se]. When B. cepacia is metabolically active, B. cepacia rapidly reduces a fraction of the SeO 32- to red elemental Se(0). In contrast, selenate is preferentially partitioned into the B. cepacia biofilms at all [Se] tested due to a lower affinity for binding to the alumina surface. Rapid reduction of SeO 42- by B. cepacia to Se(IV) and Se(0) subsequently results in a vertical segregation of Se species at the B. cepacia/α-Al 2O 3 interface. Elemental Se(0) accumulates within the biofilm with Se(VI), whereas Se(IV) intermediates preferentially sorb to the alumina surface. B. cepacia/α-Al 2O 3 samples incubated with SeO 42- and SeO 32- when the bacteria were metabolically active result in a significant reduction in the mobility of Se vs. X-ray treated biofilms. Remobilization experiments show that a large fraction of the insoluble Se(0) produced within the biofilm is retained during exchange with Se-free solutions. In addition, Se(IV) intermediates generated during Se(VI) reduction are preferentially bound to the alumina surface and do not fully desorb. In contrast, Se(VI) is rapidly and extensively remobilized.

Quality of life in the workplace for nursing staff at public healthcare institutions.

PubMed

Zavala, María Olga Quintana; Klinj, Tatiana Paravic; Carrillo, Katia Lorena Saenz

2016-08-08

to determine the quality of life in the workplace for nursing staff at public institutions in Hermosillo, Sonora, Mexico. quantitative, correlational, cross-sectional, and comparative. We used a probabilistic sample of 345 nurses with data collected in 2013 using an instrument created by the authors to gather bio-socio-demographic data and the CVT-GOHISALO instrument with a Cronbach's alpha of 0.95. SPSS 15 was used to analyze the data. A Kolmogorov-Smirnov test was used to calculate the normality of the data; the medians were compared using the Mann-Whitney U test and Kruskal-Wallis test with the significance level set at 0.05. the average overall quality of life in the workplace for nursing staff was 207.31 (DE 41.74), indicating a moderate level. The quality of life in the workplace was higher for people with permanent contracts (p=0.007) who did not engage in other remunerative activities (p=0.046). Differences in the quality of life in the workplace were observed depending on the institution where the subjects worked (p=0.001). the nursing staff perceives itself as having a moderate-level quality of life in the workplace. This level was determined in the statistical analysis based on the type of contract, whether the person performed other remunerated activities, and the institution where the person worked. determinar el nivel de calidad de vida en el trabajo del personal de enfermería de instituciones públicas en Hermosillo, Sonora, México. cuantitativo, correlacional, transversal y comparativo. Muestreo probabilístico, de 345 enfermeras, datos recolectados en 2013, a través de instrumentos que recogen datos biososiodemográficos; creado por las autoras y CVT -GOHISALO con Alpha de Cronbach de 0.95. Para el análisis de datos se usó SPSS 15, para conocer la normalidad de los datos se utilizó Kolmogorov- Smirnov, se compararon medianas con U de Mann Whitney y Kruskal-Wallis, nivel de significancia admitido 0.05. promedio de calidad de vida en el trabajo global del personal de enfermería de 207.31 (DE 41.74), que indica un nivel medio. Según forma de contratación la calidad de vida en el trabajo fue mayor en las personas con contrato indefinido (p=0.007), que no realizan otra actividad remunerada (p=0.046), con diferencias en la calidad de vida en el trabajo, según la institución en donde labora (p=0.001). el personal de enfermería se percibe con mediana calidad de vida en el trabajo, la cual está determinada de forma estadísticamente significativa por el tipo de contrato, realizar o no otra actividad remunerada y por la institución donde labora. determinar a qualidade de vida no trabalho do pessoal de enfermagem de instituições públicas em Hermosillo, Sonora, México. quantitativo, correlacional, transversal e comparativo. Amostra probabilística de 345 enfermeiras, dados coletados em 2013 utilizando instrumentos que coletam dados biossociodemográficos; elaborado pelas autoras e o instrumento CVT-GOHISALO com um alfa de Cronbach de 0.95. Para a análise de dados, foi utilizado o SPSS 15. Para determinar a normalidade dos dados, foi utilizado o teste de Kolmogorov-Smirnov; as medianas foram comparadas pelos testes U de Mann-Whitney e Kruskal-Wallis, com os níveis de significância estabelecidos em 0,05. a média da qualidade de vida do pessoal de enfermagem no trabalho é de 207,31 (DP 41,74), o que indica um nível moderado. Em relação ao tipo de contrato, a qualidade de vida no trabalho foi mais alta para pessoas com contratos permanentes (p=0,007), que não exercem outras atividades remuneradas (p=0,046), com diferenças na qualidade de vida no trabalho dependendo da instituição onde trabalham (p=0,001). o pessoal de enfermagem percebe uma média qualidade de vida no trabalho, o que é determinado de maneira significativa pelo tipo de contrato, pelo fato de exercer ou não outras atividades remuneradas e pela instituição em que a pessoa trabalha.

76 FR 37296 - Revision of Patent Fees for Fiscal Year 2012

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-27

..., (SE) $110 $230, (SE) $115 $10, (SE) $5. Application (CPA) (on or after 12/8/2004). 1.16(b)(2) Design... Application $380, (SE) $190 $390, (SE) $195 $10, (SE) $5. Filing (CPA) (before 12/8/2004). 1.16(c)(1) Filing...). 1.16(e)(1) Filing of Reissue $330, (SE) $165 $340, (SE) $170 $10, (SE) $5. Patent Application (CPA...

Selenium accumulation by plants

PubMed Central

White, Philip J.

2016-01-01

Background Selenium (Se) is an essential mineral element for animals and humans, which they acquire largely from plants. The Se concentration in edible plants is determined by the Se phytoavailability in soils. Selenium is not an essential element for plants, but excessive Se can be toxic. Thus, soil Se phytoavailability determines the ecology of plants. Most plants cannot grow on seleniferous soils. Most plants that grow on seleniferous soils accumulate <100 mg Se kg–1 dry matter and cannot tolerate greater tissue Se concentrations. However, some plant species have evolved tolerance to Se, and commonly accumulate tissue Se concentrations >100 mg Se kg–1 dry matter. These plants are considered to be Se accumulators. Some species can even accumulate Se concentrations of 1000–15 000 mg Se kg–1 dry matter and are called Se hyperaccumulators. Scope This article provides an overview of Se uptake, translocation and metabolism in plants and highlights the possible genetic basis of differences in these between and within plant species. The review focuses initially on adaptations allowing plants to tolerate large Se concentrations in their tissues and the evolutionary origin of species that hyperaccumulate Se. It then describes the variation in tissue Se concentrations between and within angiosperm species and identifies genes encoding enzymes limiting the rates of incorporation of Se into organic compounds and chromosomal loci that might enable the development of crops with greater Se concentrations in their edible portions. Finally, it discusses transgenic approaches enabling plants to tolerate greater Se concentrations in the rhizosphere and in their tissues. Conclusions The trait of Se hyperaccumulation has evolved several times in separate angiosperm clades. The ability to tolerate large tissue Se concentrations is primarily related to the ability to divert Se away from the accumulation of selenocysteine and selenomethionine, which might be incorporated into non-functional proteins, through the synthesis of less toxic Se metabilites. There is potential to breed or select crops with greater Se concentrations in their edible tissues, which might be used to increase dietary Se intakes of animals and humans. PMID:26718221

Selenium accumulation by plants.

PubMed

White, Philip J

2016-02-01

Selenium (Se) is an essential mineral element for animals and humans, which they acquire largely from plants. The Se concentration in edible plants is determined by the Se phytoavailability in soils. Selenium is not an essential element for plants, but excessive Se can be toxic. Thus, soil Se phytoavailability determines the ecology of plants. Most plants cannot grow on seleniferous soils. Most plants that grow on seleniferous soils accumulate <100 mg Se kg(-1) dry matter and cannot tolerate greater tissue Se concentrations. However, some plant species have evolved tolerance to Se, and commonly accumulate tissue Se concentrations >100 mg Se kg(-1) dry matter. These plants are considered to be Se accumulators. Some species can even accumulate Se concentrations of 1000-15 000 mg Se kg(-1 )dry matter and are called Se hyperaccumulators. This article provides an overview of Se uptake, translocation and metabolism in plants and highlights the possible genetic basis of differences in these between and within plant species. The review focuses initially on adaptations allowing plants to tolerate large Se concentrations in their tissues and the evolutionary origin of species that hyperaccumulate Se. It then describes the variation in tissue Se concentrations between and within angiosperm species and identifies genes encoding enzymes limiting the rates of incorporation of Se into organic compounds and chromosomal loci that might enable the development of crops with greater Se concentrations in their edible portions. Finally, it discusses transgenic approaches enabling plants to tolerate greater Se concentrations in the rhizosphere and in their tissues. The trait of Se hyperaccumulation has evolved several times in separate angiosperm clades. The ability to tolerate large tissue Se concentrations is primarily related to the ability to divert Se away from the accumulation of selenocysteine and selenomethionine, which might be incorporated into non-functional proteins, through the synthesis of less toxic Se metabilites. There is potential to breed or select crops with greater Se concentrations in their edible tissues, which might be used to increase dietary Se intakes of animals and humans. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} and the role of dimensionality in the Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} series

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trump, Benjamin A., E-mail: btrump1@jhu.edu; Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218; Livi, Kenneth J.T.

The synthesis and physical properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} are reported. Transmission electron microscopy and powder X-ray diffraction show that the structure consists of alternating rock-salt type BiSe layers and hexagonal (TiSe{sub 2}){sub 2} double layers. Resistivity, specific heat, and magnetization measurements show that it has metallic and diamagnetic behaviors. These results are interpreted and discussed in the context of the transition between single-layer (BiSe){sub 1.13}(TiSe{sub 2}), which shows no charge density wave, and infinite-layered (bulk) 1T-TiSe{sub 2}, which undergoes a charge density wave transition at T=202 K. Intercalation with copper, Cu{sub x}(BiSe){sub 1.15}(TiSe{sub 2}){submore » 2}, (0≤x≤0.10) is also reported, but unlike Cu{sub x}TiSe{sub 2}, no superconductivity is observed down to T=0.05 K. Thus, the series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} provides an effective approach to elucidate the impact of dimensionality on charge density wave formation and superconductivity. - Graphical abstract: The newly discovered misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} shown in the series (BiSe){sub 1+δ}(TiSe{sub 2}){sub n}. Display Omitted - Highlights: • Reports the structure and properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2}. • The structure consists of a rock salt type BiSe layer and a double (TiSe{sub 2}){sub 2} layer. • The n=1, 2 misfits (BiSe){sub 1+δ}(TiSe{sub 2}){sub n} are found not to exhibit CDW transitions. • Evidence is presented that there is likely a low-lying CDW excited state. • The series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub 2} does not superconduct, unlike Cu{sub x}TiSe{sub 2}.« less

Comparison of the metabolism of inorganic and organic selenium species between two selenium accumulator plants, garlic and Indian mustard.

PubMed

Ogra, Yasumitsu; Ogihara, Yurie; Anan, Yasumi

2017-01-25

The metabolism of selenomethionine (SeMet) in two major selenium (Se) accumulator plants, garlic and Indian mustard, was compared to that of stable isotope labeled selenate. Indian mustard more efficiently transported Se from roots to leaves than garlic. In addition, Indian mustard accumulated larger amounts of Se than garlic. γ-Glutamyl-Se-methylselenocysteine (γ-GluMeSeCys) and Se-methylselenocysteine (MeSeCys) were the common metabolites of selenate and SeMet in garlic and Indian mustard. Indian mustard had a specific metabolic pathway to selenohomolanthionine (SeHLan) from both inorganic and organic Se species. SeMet was a more effective fertilizer for cultivating Se-enriched plants than selenate in terms of the production of selenoamino acids.

Reverse Monte Carlo simulation of Se{sub 80}Te{sub 20} and Se{sub 80}Te{sub 15}Sb{sub 5} glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel-Baset, A. M.; Rashad, M.; Moharram, A. H.

2013-12-16

Two-dimensional Monte Carlo of the total pair distribution functions g(r) is determined for Se{sub 80}Te{sub 20} and Se{sub 80}Te{sub 15}Sb{sub 5} alloys, and then it used to assemble the three-dimensional atomic configurations using the reverse Monte Carlo simulation. The partial pair distribution functions g{sub ij}(r) indicate that the basic structure unit in the Se{sub 80}Te{sub 15}Sb{sub 5} glass is di-antimony tri-selenide units connected together through Se-Se and Se-Te chain. The structure of Se{sub 80}Te{sub 20} alloys is a chain of Se-Te and Se-Se in addition to some rings of Se atoms.

[Selenium uptake and transport of rice under different Se-enriched natural soils].

PubMed

Jiang, Chao-qiang; Shen, Jia; Zu, Chao-long

2015-03-01

In this study, a pot experiment was conducted with "Wandao 205" as test materials to investigate Se uptake and translocation in rice under different Se concentrations (0.5, 1.0, and 1.5 mg . kg-1). Results showed that there was no significant change in rice yield when Se concentration in soil was lower than 1.5 mg . kg-1. Significant linear correlations existed between Se concentration in soil and different rice plant tissues. Se concentration in rice plant followed the order of root > straw > grain. Se concentration in different rice grain fractions followed the order of bran > polished rice > hull. The root absorption index of Se was more than 1.86, suggest that the rice could absorpt Se from soil effectively. However, the transport and accumulation of Se in seeds from Se-enriched soil was relatively constant. The Se transport index in seeds was between 0.53 and 0.59. Soil Se concentration within the range of 0.5 to 1.0 mg . kg-1 could produce Se-enriched rice, which might be enough for human requirement of 60-80 µg . d-1 Se. However, polished rice at high-Se treatment (1.5 mg . kg-1) exceeded the maximum standard limit of Se (0.3 mg . kg-1) for cereals in China. These results suggested that we could produce Se-enriched rice under soil Se concentration in the range of 0.5 to 1.0 mg . kg-1 without spraying Se fertilizer, thus reducing the cost and avoiding soil and water pollution caused by exogenous Se.

A selenium-deficient Caco-2 cell model for assessing differential incorporation of chemical or food selenium into glutathione peroxidase.

PubMed

Zeng, Huawei; Botnen, James H; Johnson, Luann K

2008-01-01

Assessing the ability of a selenium (Se) sample to induce cellular glutathione peroxidase (GPx) activity in Se-deficient animals is the most commonly used method to determine Se bioavailability. Our goal is to establish a Se-deficient cell culture model with differential incorporation of Se chemical forms into GPx, which may complement the in vivo studies. In the present study, we developed a Se-deficient Caco-2 cell model with a serum gradual reduction method. It is well recognized that selenomethionine (SeMet) is the major nutritional source of Se; therefore, SeMet, selenite, or methylselenocysteine (SeMSC) was added to cell culture media with different concentrations and treatment time points. We found that selenite and SeMSC induced GPx more rapidly than SeMet. However, SeMet was better retained as it is incorporated into proteins in place of methionine; compared with 8-, 24-, or 48-h treatment, 72-h Se treatment was a more sensitive time point to measure the potential of GPx induction in all tested concentrations. Based on induction of GPx activity, the cellular bioavailability of Se from an extract of selenobroccoli after a simulated gastrointestinal digestion was comparable with that of SeMSC and SeMet. These in vitro data are, for the first time, consistent with previous published data regarding selenite and SeMet bioavailability in animal models and Se chemical speciation studies with broccoli. Thus, Se-deficient Caco-2 cell model with differential incorporation of chemical or food forms of Se into GPx provides a new tool to study the cellular mechanisms of Se bioavailability.

Biomarkers in critically ill patients with systemic inflammatory response syndrome or sepsis supplemented with high-dose selenium.

PubMed

Brodska, Helena; Valenta, Jiri; Malickova, Karin; Kohout, Pavel; Kazda, Antonin; Drabek, Tomas

2015-01-01

Low levels of selenium (Se) and glutathione peroxidase (GSHPx), a key selenoenzyme, were documented in systemic inflammatory response syndrome (SIRS) and sepsis, both associated with high mortality. Se supplementation had mixed effects on outcome. We hypothesized that Se supplementation could have a different impact on biomarkers and 28-day mortality in patients with SIRS vs. sepsis. Adult patients with SIRS or sepsis were randomized to either high-dose (Se+, n = 75) or standard-dose (Se-, n = 75) Se supplementation. Plasma Se, whole blood GSHPx activity, C-reactive protein (CRP), procalcitonin (PCT), prealbumin, albumin and cholesterol levels were measured serially up to day 14. There was no difference in mortality between Se- (24/75) vs. Se+ group (19/75; p = 0.367) or between SIRS and septic patients (8/26 vs. 35/124; p = 0.794). There was a trend to reduced mortality in SIRS patients in the Se+ vs. Se- group (p = 0.084). Plasma Se levels increased in the Se+ group only in patients with sepsis but not in patients with SIRS. Plasma Se levels correlated with GSHPx. In SIRS/Se+ group, Se correlated only with GSHPx. In SIRS/Se- group, Se correlated with cholesterol but not with other biomarkers. In sepsis patients, Se levels correlated with cholesterol, GSHPx and prealbumin. Cholesterol levels were higher in survivors in the Se- group. Se levels correlated with GSHPx activity and other nutritional biomarkers with significant differences between SIRS and sepsis groups. High-dose Se supplementation did not affect mortality but a strong trend to decreased mortality in SIRS patients warrants further studies in this population. Copyright © 2015 Elsevier GmbH. All rights reserved.

Microbial oxidation of elemental selenium in soil slurries and bacterial cultures

USGS Publications Warehouse

Dowdle, P.R.; Oremland, R.S.

1998-01-01

The microbial oxidation of elemental selenium [Se(O)] was studied by employing 75Se(O) as a tracer. Live, oxic soil slurries demonstrated a linear production of mostly Se(IV), with the formation of smaller quantities of Se(VI). Production of both Se(IV) and Se(VI) was inhibited by autoclaving, formalin, antibiotics, azide, and 2,4-dinitrophenol, thereby indicating the involvement of microbes. Oxidation of Se(O) in slurries was enhanced by addition of acetate, glucose, or sulfide, which implied involvement of chemoheterotrophs as well as chemoautotrophic thiobacilli. Cultures of Thiobacillus ASN-1, Leptothrix MnB1, and a heterotrophic soil enrichment all oxidized Se(O) with Se(VI) observed as the major product rather than Se(IV). This indicated that microbial oxidation in soils is partly constrained by the adsorption of Se(IV) onto soil surfaces. Rate constants for unamended soil slurry Se(O) oxidation ranged from 0.0009 to 0.0117 day-1 which were 3-4 orders of magnitude lower than those reported for dissimilatory Se(VI) reduction in organic-rich, anoxic sediments.The microbial oxidation of elemental selenium [Se(0)] was studied by employing 75Se(0) as a tracer. Live, oxic soil slurries demonstrated a linear production of mostly Se(IV), with the formation of smaller quantities of Se(VI). Production of both Se(IV) and Se(VI) was inhibited by autoclaving, formalin, antibiotics, azide, and 2,4-dinitrophenol, thereby indicating the involvement of microbes. Oxidation of Se(O) in slurries was enhanced by addition of acetate, glucose, or sulfide, which implied involvement of chemoheterotrophs as well as chemoautotrophic thiobacilli. Cultures of Thiobacillus ASN-1, Leptothrix MnB1, and a heterotrophic soil enrichment all oxidized Se(O) with Se(VI) observed as the major product rather than Se(IV). This indicated that microbial oxidation in soils is partly constrained by the adsorption of Se(IV) onto soil surfaces. Rate constants for unamended soil slurry Se(O) oxidation ranged from 0.0009 to 0.0117 day-1 which were 3-4 orders of magnitude lower than those reported for dissimilatory Se(VI) reduction in organic-rich, anoxic sediments.

[Effects of sulfur on transformation of selenium in soil and uptake of selenium in rape].

PubMed

Liu, Xin-wei; Duan, Bi-huil; Xia, Quan-jie; Jiao, Wei; Guo, Zai-hua; Hu, Cheng-xiao; Zhao, Zhu-qing

2014-09-01

The high-quality, high-yield rape (Brassica napus L. cv. Xiangnongyou 571) was chosen as the experimental material to undergo seedling stage soil cultivation and solution cultivation. This study was aimed to investigate the effects of sulfur (S) on the fraction and species of amend selenium (Se) in soil by applying S fertilizer, and to reveal the mechanism through which S controls the Se uptake of rape. The results showed that applications of both Se at 5 mg.kg-1 and S at 150 mg.kg-1 could provide some boost to rape growth, however such boost was unremarkable; S application could significantly reduce Se content in shoots and roots by as much as 64. 0% and 39. 1% , respectively; S application could significantly decrease the pH value and increase the organic matter content by as much as 0. 65 units and 1.76 g.kg-1 , respectively; S application could significantly decrease soluble Se and Fe/Mn oxide-bound Se, and significantly increase organic matter-bound Se, however, there was no remarkable effect on exchangeable and residual Se. S could significantly decrease the content of Se(IV) in the soluble Se and significantly increase the content of Se(IV) in the exchangeable Se, with remarkable decrease in Se(VI) content in both fractions, and no remarkable effect on Se(II). S had a profound effect on the uptake of Se by rape seedlings when Se( IV) and Se( VI) were applied. The Se contents in shoot and root of the Se( VI)-treated rape were 7.3 and 3.2 times respectively as high as that of the Se( IV)-treated rape, while with a S rate of 2 mmolL-1, their Se contents were lower than 32.6% and 8.7% of that of the Se(IV)-treated rape. In conclusion, in addition to improving crop growth, appropriate amount of S fertilizer could also reduce soil pH and increase organic content, causing available Se in soil to be Fe/Mn oxide-bound and organic matter-bound, and retarding its transformation to Se( VI), thus reducing Se uptake by rape. This has significant value for regulation of Se content in crops from Se-rich regions, ensuring food quality and safety, benefiting the long-term use of soil Se resources and regional economic development.

Stable selones in glutathione-peroxidase-like catalytic cycle of selenonicotinamide derivative.

PubMed

Prabhu, Parashiva; Singh, Beena G; Noguchi, Masato; Phadnis, Prasad P; Jain, Vimal K; Iwaoka, Michio; Priyadarsini, K Indira

2014-04-21

Selenonicotinamide, 2,2'-diselenobis[3-amidopyridine] (NictSeSeNict) exhibits glutathione-peroxidase (GPx)-like activity, catalyzing the reduction of hydrogen peroxide (H2O2) by glutathione (GSH). Estimated reactivity parameters for the reaction of selenium species, according to the Dalziel kinetic model, towards GSH (ϕGSH) and H2O2 (ϕH2O2), indicated that the rate constant for the reaction of NictSeSeNict with GSH is higher as compared to that with H2O2, indicating that the activity is initiated by reduction. (77)Se NMR spectroscopy, HPLC analysis, mass spectrometry (MS) and absorption spectroscopy were employed to understand the nature of selenium intermediates responsible for the activity. The (77)Se NMR resonance at 525 ppm due to NictSeSeNict disappeared in the presence of GSH with the initial appearance of signals at δ 364 and 600 ppm, assigned to selone (NictC=Se) and selenenyl sulfide (NictSeSG), respectively. Reaction of H2O2 with NictSeSeNict produced a mixture of selenenic acid (NictSeOH) and seleninic acid (NictSeO2H) with (77)Se NMR resonances appearing at 1069 and 1165 ppm, respectively. Addition of three equivalents of GSH to this mixture produced a characteristic (77)Se NMR signal of NictSeSG. HPLC analysis of the product formed by the reaction of NictSeSeNict with GSH confirmed the formation of NictC=Se absorbing at 375 nm. Stopped-flow kinetic studies with global analysis revealed a bimolecular rate constant of 4.8 ± 0.5 × 10(3) M(-1) s(-1) and 1.7 ± 0.6 × 10(2) M(-1) s(-1) for the formation of NictC=Se produced in two consecutive reactions of NictSeSeNict and NictSeSG with GSH, respectively. Similarly the rate constant for the reaction of NictC=Se with H2O2 was estimated to be 18 ± 1.8 M(-1) s(-1). These studies clearly indicated that the GPx activity of NictSeSeNict is initiated by reduction to form NictSeSG and a stable selone, which is responsible for its efficient GPx activity.

Selenium requirements based on muscle and kidney selenoprotein enzyme activity and transcript expression in the turkey poult (Meleagris gallopavo).

PubMed

Taylor, Rachel M; Sunde, Roger A

2017-01-01

The current NRC selenium (Se) requirement for turkeys is 0.2 μg Se/g diet. We previously fed turkey poults a Se-deficient diet (0.005 μg Se/g) supplemented with 10 graded levels of Se (0, 0.025, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0 μg Se/g as Na2SeO3, 5/treatment) for 4 wk, and found that the minimum dietary Se requirement was 0.3 μg Se/g based on selenoprotein enzyme activity in blood, liver, gizzard and pancreas. Because the turkey is primarily a production animal, we expanded this analysis to kidney, heart, breast and thigh. Se concentrations in Se-deficient poults were 5.0, 9.8, 33, and 15% of levels in poults fed 0.4 μg Se/g in liver, kidney, thigh and breast, respectively. Increasing Se supplementation resulted in hyperbolic response curves for all tissues; breakpoint analysis indicated minimum Se requirements of 0.34-0.36 μg Se/g based on tissue Se levels in liver, kidney and thigh. Similarly, GPX1 activity in muscle tissues and kidney responded hyperbolically to increasing dietary Se, reaching well-defined plateaus with breakpoints at 0.30-0.36 μg Se/g. Minimum Se requirements based on GPX4 activity were 0.30-0.32 μg Se/g for breast and thigh. Selenoprotein transcript expression decreased significantly in Se deficiency for only 2, 3, 5, and 6 mRNA in breast, thigh, heart, and kidney, respectively, out of 24 known avian selenoproteins. Se response curves for regulated selenoprotein transcripts were hyperbolic, and reached well-defined plateaus with breakpoints in a narrow range of 0.08-0.19 μg Se/g. No selenoprotein transcript was altered by supernutritional Se. In summary, these results clearly indicate that the NRC dietary Se requirement should be raised to 0.4 μg Se/g, at least for poults, to meet the nutritional needs of the young turkey. The Se response curve plateaus further show that limits for turkey supplementation with selenite could safely be raised to 0.5 μg Se/g diet.

Continued selenium biofortification of carrots and broccoli grown in soils once amended with Se-enriched S. pinnata

USDA-ARS?s Scientific Manuscript database

Selenium (Se) biofortification has been practiced in Se-deficient regions throughout the world primarily by adding inorganic sources of Se to the soil. Adding organic sources of Se could be useful as an alternative Se amendment for the production of Se-biofortified food crops needed in Se-deficient ...

Delayed formation of zero-valent selenium nanoparticles by Bacillus mycoides SeITE01 as a consequence of selenite reduction under aerobic conditions

PubMed Central

2014-01-01

Background Selenite (SeO32−) oxyanion shows severe toxicity to biota. Different bacterial strains exist that are capable of reducing SeO32− to non-toxic elemental selenium (Se0), with the formation of Se nanoparticles (SeNPs). These SeNPs might be exploited for technological applications due to their physico-chemical and biological characteristics. The present paper discusses the reduction of selenite to SeNPs by a strain of Bacillus sp., SeITE01, isolated from the rhizosphere of the Se-hyperaccumulator legume Astragalus bisulcatus. Results Use of 16S rRNA and GyrB gene sequence analysis positioned SeITE01 phylogenetically close to B. mycoides. On agarized medium, this strain showed rhizoid growth whilst, in liquid cultures, it was capable of reducing 0.5 and 2.0 mM SeO32− within 12 and 24 hours, respectively. The resultant Se0 aggregated to form nanoparticles and the amount of Se0 measured was equivalent to the amount of selenium originally added as selenite to the growth medium. A delay of more than 24 hours was observed between the depletion of SeO32 and the detection of SeNPs. Nearly spherical-shaped SeNPs were mostly found in the extracellular environment whilst rarely in the cytoplasmic compartment. Size of SeNPs ranged from 50 to 400 nm in diameter, with dimensions greatly influenced by the incubation times. Different SeITE01 protein fractions were assayed for SeO32− reductase capability, revealing that enzymatic activity was mainly associated with the membrane fraction. Reduction of SeO32− was also detected in the supernatant of bacterial cultures upon NADH addition. Conclusions The selenite reducing bacterial strain SeITE01 was attributed to the species Bacillus mycoides on the basis of phenotypic and molecular traits. Under aerobic conditions, the formation of SeNPs were observed both extracellularly or intracellullarly. Possible mechanisms of Se0 precipitation and SeNPs assembly are suggested. SeO32− is proposed to be enzimatically reduced to Se0 through redox reactions by proteins released from bacterial cells. Sulfhydryl groups on peptides excreted outside the cells may also react directly with selenite. Furthermore, membrane reductases and the intracellular synthesis of low molecular weight thiols such as bacillithiols may also play a role in SeO32− reduction. Formation of SeNPs seems to be the result of an Ostwald ripening mechanism. PMID:24606965

Selenium status in adult cats and dogs fed high levels of dietary inorganic and organic selenium.

PubMed

Todd, S E; Thomas, D G; Bosch, G; Hendriks, W H

2012-08-01

Cats (Felis catus) maintain greater blood Se concentrations compared with dogs (Canis familiaris) and, unlike dogs, show no signs of chronic Se toxicity (selenosis) when fed dietary organic Se (selenomethionine) concentrations of 10 μg/g DM. This study investigated the response of cats and dogs to high dietary concentrations of sodium selenite and organic Se to determine differences in metabolism between both species. In 2 consecutive studies, 18 adult cats and 18 adult dogs of with equal numbers of each sex were fed a control diet (0.6 μg Se/g DM) or the control diet supplemented to 8 to 10 μg Se/g DM from Na(2)SeO(3) or organic Se for 3 wk. All animals were fed the control diet 1 mo before the start of the study and blood samples were taken on d 0 and 21. The Se balance was assessed during the final week and a liver biopsy was obtained on the final day of the study. Measurements included plasma Se concentrations, plasma glutathione peroxidise (GPx) activities, plasma Se clearance, Se intake, and urinary Se excretion. No clinical signs of selenosis were observed in the cats or dogs, and apart from Se clearance, form of Se had no effect on any of the measurements. Apparent fecal Se absorption was greater in the dogs fed both forms of Se, while greater plasma Se concentrations were observed in the cats on both the control and supplemented diet (P = 0.034). Cats fed the supplemented diets had lower hepatic Se concentrations (P < 0.001) and excreted more Se in urine (P < 0.001) compared with dogs. Furthermore, cats fed the Na(2)SeO(3) supplement had greater Se clearance rates than dogs (P < 0.001). There was no effect of species on plasma GPx activity. We conclude that cats can tolerate greater dietary Se concentrations as they are more efficient at excreting excess Se in the urine and storing less Se in the liver.

[Effect of nano-selenium on the activities of glutathione peroxidase and type-I deiodinase in the liver of weanling pigs].

PubMed

Zhang, Hongmei; Xia, Meisheng; Hu, Caihong

2007-02-01

To study the effects of nano elemental selenium (Nano-Se) or sodium selenite (Na2SeO3) on the activities of glutathione peroxidase (GSH-Px) and Type-I deiodinase in the liver. A total of 234 weanling pigs (Duroc x Landrace x Yorkshire) at an average initial body weight of 8.3 kg were allocated to 13 treatments. The thirteen dietary treatments were basal diet only (containing 0.04 mg/kg Se), basal diet + 0.1, 0.2, 0.3, 0.4, 0.5, 1.0 mg/kg Se as Na2SeO3 or Nano-Se, respectively. The results were as follows: Supplementation with 1.0 mg/ kg Se as Na2SeO3 reduced (P < 0.05) growth performance and GSH-Px activities as compared with the addition of a concentration range of 0.20-0.40 mg/kg Se. When Nano-Se was added to the diet, the growth and GSH-Px activities remained steady at the peak value as at a concentration of 1.0 mg/kg Se; There were no difference in the activities of GSH-Px between the treatments of Nano-Se and Na2SeO3 when added concentration of Se was 0.10-0.40 mg/kg. The pigs had higher (P < 0.05) activities of GSH-Px at a concentration range of 0.50 and 1.0 mg/kg as Nano-Se than Na2SeO3; Supplentation with Se increased the activity of Type- I deiodinase in liver, however, the increased extent was affected by neither Se sources nor added concentration of Se. The results implicated that for the best concentration range of Weinberg curve, Nano-Se is wider than Na2SeO3.

Bioaccumulation of organic and inorganic selenium in a laboratory food chain

USGS Publications Warehouse

Besser, John M.; Canfield, Timothy J.; La Point, Thomas W.

1993-01-01

Aquatic organisms accumulated selenium (Se) from inorganic and organic Se species via aqueous and food-chain exposure routes. We measured aqueous and food-chain Se bioaccumulation from selenate, selenite, and seleno-L-methionine in a laboratory food chain of algae (Chlamydomonas reinhardtii), daphnids (Daphnia magna), and fish (bluegill, Lepomis macrochirus). Selenium concentrations were monitored radiometrically with 75Se-labeled compounds. All three organisms concentrated Se more strongly from aqueous selenomethionine than from either inorganic Se species. Bioconcentration factors (BCFs) estimated from 1 μg Se/L Se-methionine exposures were approximately 16,000 for algae, 200,000 for daphnids, and 5,000 for bluegills. Algae and daphnids concentrated Se more strongly from selenite (BCFs = 220–3,600) than selenate (BCFs = 65–500) whereas bluegills concenrated Se about equally from both inorganic species (estimated BCFs = 13 to 106). Bioaccumulation of foodborne Se by daphnids and bluegills was similar in food chains dosed with different Se species. Daphnids and bluegills did not accumulate Se concentrations greater than those in their diet, except at very low dietary Se concentrations. Food-chain concentration factors (CFs) for daphnids decreased from near 1.0 to 0.5 with increases in algal Se concentrations, whereas CFs estimated from bluegill exposures averaged 0.5 over a range of foodborne Se concentrations. In exposures based on selenite, bluegills accumulated greater Se concentrations from food than from water. Aqueous and food-chain Se uptakes were approximately additive, and depuration rates were similar in aqueous, food-chain, and combined exposures. Our results suggest that bluegills in Secontaminated habitats accumulate inorganic Se species primarily via food-chain uptake, although organoselenium compounds such as Se-methionine may contribute significantly to Se bioaccumulation by bluegills via both aqueous and food-chain uptake.

Early Cannabis Use, Polygenic Risk Score for Schizophrenia, and Brain Maturation in Adolescence

PubMed Central

French, Leon; Gray, Courtney; Leonard, Gabriel; Perron, Michel; Pike, G. Bruce; Richer, Louis; Séguin, Jean R.; Veillette, Suzanne; Evans, C. John; Artiges, Eric; Banaschewski, Tobias; Bokde, Arun W. L.; Bromberg, Uli; Bruehl, Ruediger; Buchel, Christian; Cattrell, Anna; Conrod, Patricia J.; Flor, Herta; Frouin, Vincent; Gallinat, Jurgen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Lemaitre, Herve; Martinot, Jean-Luc; Nees, Frauke; Orfanos, Dimitri Papadopoulos; Pangelinan, Melissa Marie; Poustka, Luise; Rietschel, Marcella; Smolka, Michael N.; Walter, Henrik; Whelan, Robert; Timpson, Nic J.; Schumann, Gunter; Smith, George Davey; Pausova, Zdenka; Paus, Tomáš

2016-01-01

IMPORTANCE Cannabis use during adolescence is known to increase the risk for schizophrenia in men. Sex differences in the dynamics of brain maturation during adolescence may be of particular importance with regard to vulnerability of the male brain to cannabis exposure. OBJECTIVE To evaluate whether the association between cannabis use and cortical maturation in adolescents is moderated by a polygenic risk score for schizophrenia. DESIGN, SETTING, AND PARTICIPANTS Observation of 3 population-based samples included initial analysis in 1024 adolescents of both sexes from the Canadian Saguenay Youth Study (SYS) and follow-up in 426 adolescents of both sexes from the IMAGEN Study from 8 European cities and 504 male youth from the Avon Longitudinal Study of Parents and Children (ALSPAC) based in England. A total of 1577 participants (aged 12–21 years; 899 [57.0%] male) had (1) information about cannabis use; (2) imaging studies of the brain; and (3) a polygenic risk score for schizophrenia across 108 genetic loci identified by the Psychiatric Genomics Consortium. Data analysis was performed from March 1 through December 31, 2014. MAIN OUTCOMES AND MEASURES Cortical thickness derived from T1-weighted magnetic resonance images. Linear regression tests were used to assess the relationships between cannabis use, cortical thickness, and risk score. RESULTS Across the 3 samples of 1574 participants, a negative association was observed between cannabis use in early adolescence and cortical thickness in male participants with a high polygenic risk score. This observation was not the case for low-risk male participants or for the low- or high-risk female participants. Thus, in SYS male participants, cannabis use interacted with risk score vis-à-vis cortical thickness (P = .009); higher scores were associated with lower thickness only in males who used cannabis. Similarly, in the IMAGEN male participants, cannabis use interacted with increased risk score vis-à-vis a change in decreasing cortical thickness from 14.5 to 18.5 years of age (t137 = −2.36; P = .02). Finally, in the ALSPAC high-risk group of male participants, those who used cannabis most frequently (≥61 occasions) had lower cortical thickness than those who never used cannabis (difference in cortical thickness, 0.07 [95% CI, 0.01–0.12]; P = .02) and those with light use (<5 occasions) (difference in cortical thickness, 0.11 [95% CI, 0.03–0.18]; P = .004). CONCLUSIONS AND RELEVANCE Cannabis use in early adolescence moderates the association between the genetic risk for schizophrenia and cortical maturation among male individuals. This finding implicates processes underlying cortical maturation in mediating the link between cannabis use and liability to schizophrenia. PMID:26308966

Selenium and breast-feeding.

PubMed

Dorea, Jose G

2002-11-01

The objective of the present review is to discuss Se nutrition during breast-feeding, encompassing environmental and maternal constitutional factors affecting breast-milk-Se metabolism and secretion. A literature search of Medline and Webofscience was used to retrieve and select papers dealing with Se and breast milk. Although Se in natural foods occurs only in organic form, breast milk responds to organic and inorganic Se in supplements. Inorganic Se (selenite, selenate), which is largely used in maternal supplements, is not detectable in breast milk. The mammary-gland regulating mechanism controls the synthesis and secretion of seleno-compounds throughout lactation, with a high total Se level in colostrum that decreases as lactation progresses. Se appears in breast milk as a component of specific seleno-proteins and seleno-amino-acids in milk proteins that are well tolerated by breast-fed infants even in high amounts. Se in breast milk occurs as glutathione peroxidase (4-32 % total Se) > selenocystamine > selenocystine > selenomethionine. The wide range of breast-milk Se concentrations depends on Se consumed in natural foods, which reflects the Se content of the soils where they are grown. Se prophylaxis, either through soil Se fertilization or maternal supplements, is effective in raising breast-milk Se concentration. In spite of wide variation, the median Se concentration from studies worldwide are 26, 18, 15, and 17 microg/l in colostrum (0-5 d), transitional milk (6-21 d), mature milk (1-3 months) and late lactation (>5 months) respectively. Se recommendations for infants are presently not achieved in 30 % of the reported breast-milk Se concentrations; nevertheless Se status is greater in breast-fed than in formula-fed infants.

Review: Selenium contamination, fate, and reactive transport in groundwater in relation to human health

NASA Astrophysics Data System (ADS)

Bailey, Ryan T.

2017-06-01

Selenium (Se) is an essential micro-nutrient for humans, but can be toxic at high levels of intake. Se deficiency and Se toxicity are linked with serious diseases, with some regions worldwide experiencing Se deficiency due to Se-poor rocks and soils and other areas dealing with Se toxicity due to the presence of Se-enriched geologic materials. In addition, Se is consumed primarily through plants that take up Se from soil and through animal products that consume these plants. Hence, the soil and groundwater system play important roles in determining the effect of Se on human health. This paper reviews current understanding of Se fate and transport in soil and groundwater systems and its relation to human health, with a focus on alluvial systems, soil systems, and the interface between alluvial systems and Cretaceous shale that release Se via oxidation processes. The review focuses first on the relation between Se and human health, followed by a summary of Se distribution in soil-aquifer systems, with an emphasis on the quantitative relationship between Se content in soil and Se concentration in underlying groundwater. The physical, chemical, and microbial processes that govern Se fate and transport in subsurface systems then are presented, followed by numerical modeling techniques used to simulate these processes in study regions and available remediation strategies for either Se-deficient or Se-toxic regions. This paper can serve as a guide to any field, laboratory or modeling study aimed at assessing Se fate and transport in groundwater systems and its relation to human health.

Selenium hyperaccumulation by Astragalus (Fabaceae) does not inhibit root nodule symbiosis.

PubMed

Alford, Elan R; Pilon-Smits, Elizabeth A H; Fakra, Sirine C; Paschke, Mark W

2012-12-01

A survey of the root-nodule symbiosis in Astragalus and its interaction with selenium (Se) has not been conducted before. Such studies can provide insight into how edaphic conditions modify symbiotic interactions and influence partner coevolution. In this paper plant-organ Se concentration ([Se]) was investigated to assess potential Se exposure to endophytes. • Selenium distribution and molecular speciation of root nodules from Se-hyperaccumulators Astragalus bisulcatus, A. praelongus, and A. racemosus was determined by Se K-edge x-ray absorption spectroscopy. A series of greenhouse experiments were conducted to characterize the response of root-nodule symbiosis in Se-hyperaccumulators and nonhyperaccumulators. • Nodules in three Se-hyperaccumulators (Astragalus crotalariae, A. praelongus, and A. preussii) are reported for the first time. Leaves, flowers, and fruits from Se-hyperaccumulators were routinely above the hyperaccumulator threshold (1,000 µg Se g(-1) DW), but root samples rarely contained that amount, and nodules never exceeded 110 µg Se g(-1) DW. Nodules from A. bisulcatus, A. praelongus, and A. racemosus had Se throughout, with a majority stored in C-Se-C form. Finally, an evaluation of nodulation in Se-hyperaccumulators and nonhyperaccumulators indicated that there was no nodulation inhibition because of plant Se tolerance. Rather, we found that in Se-hyperaccumulators higher levels of Se treatment (up to 100 µM Se) corresponded with higher nodule counts, indicating a potential role for dinitrogen fixation in Se-hyperaccumulation. The effect was not found in nonhyperaccumulators. • As the evolution of Se hyperaccumulation in Astragalus developed, root-nodule symbiosis may have played an integral role.

Preparation and antioxidant properties of selenium nanoparticles-loaded chitosan microspheres.

PubMed

Bai, Kaikai; Hong, Bihong; He, Jianlin; Hong, Zhuan; Tan, Ran

2017-01-01

Selenium nanoparticles (SeNPs), as a special form of selenium (Se) supplement, have attracted worldwide attention due to their favorable properties and unique bioactivities. Herein, an eco-friendly and economic way to prepare stable SeNPs is introduced. SeNPs were synthesized in aqueous chitosan (CTS) and then embedded into CTS microspheres by spray-drying, forming selenium nanoparticles-loaded chitosan microspheres (SeNPs-M). The physicochemical properties including morphology, elemental state, size distribution and surface potential were investigated. Institute of Cancer Research mice were used as model animal to evaluate the bioactivities of SeNPs-M. Trigonal-phase SeNPs of ~35 nm were synthesized, and SeNPs-M physically embedding those SeNPs were successfully prepared. Amazingly, acute toxicity test indicated that SeNPs-M were much safer than selenite in terms of Se dose, with a LD 50 of around 18-fold of that of selenite. In addition, SeNPs-M possessed powerful antioxidant activities, as evidenced by a dramatic increase of both Se retention and the levels of glutathione peroxidase, superoxide dismutase and catalase. The design of SeNPs-M can offer a new way for further development of SeNPs with a higher efficacy and better biosafety. Thus, SeNPs-M may be a potential candidate for further evaluation as an Se supplement with antioxidant properties and be used against Se deficiency in animals and human beings.

Preparation and antioxidant properties of selenium nanoparticles-loaded chitosan microspheres

PubMed Central

Bai, Kaikai; Hong, Bihong; He, Jianlin; Hong, Zhuan; Tan, Ran

2017-01-01

Selenium nanoparticles (SeNPs), as a special form of selenium (Se) supplement, have attracted worldwide attention due to their favorable properties and unique bioactivities. Herein, an eco-friendly and economic way to prepare stable SeNPs is introduced. SeNPs were synthesized in aqueous chitosan (CTS) and then embedded into CTS microspheres by spray-drying, forming selenium nanoparticles-loaded chitosan microspheres (SeNPs-M). The physicochemical properties including morphology, elemental state, size distribution and surface potential were investigated. Institute of Cancer Research mice were used as model animal to evaluate the bioactivities of SeNPs-M. Trigonal-phase SeNPs of ~35 nm were synthesized, and SeNPs-M physically embedding those SeNPs were successfully prepared. Amazingly, acute toxicity test indicated that SeNPs-M were much safer than selenite in terms of Se dose, with a LD50 of around 18-fold of that of selenite. In addition, SeNPs-M possessed powerful antioxidant activities, as evidenced by a dramatic increase of both Se retention and the levels of glutathione peroxidase, superoxide dismutase and catalase. The design of SeNPs-M can offer a new way for further development of SeNPs with a higher efficacy and better biosafety. Thus, SeNPs-M may be a potential candidate for further evaluation as an Se supplement with antioxidant properties and be used against Se deficiency in animals and human beings. PMID:28684913

Influence of Dietary Selenium Species on Selenoamino Acid Levels in Rainbow Trout.

PubMed

Godin, Simon; Fontagné-Dicharry, Stéphanie; Bueno, Maïté; Tacon, Philippe; Prabhu, Philip Antony Jesu; Kaushik, Sachi; Médale, Françoise; Bouyssiere, Brice

2015-07-22

Two forms of selenium (Se) supplementation of fish feeds were compared in two different basal diets. A 12-week feeding trial was performed with rainbow trout fry using either a plant-based or a fish meal-based diet. Se yeast and selenite were used for Se supplementation. Total Se and Se speciation were determined in both diets and whole body of trout fry using inductively coupled plasma mass spectrometry (ICP MS) and high-performance liquid chromatography (HPLC). The two selenoamino acids, selenomethionine (SeMet) and selenocysteine (SeCys), were determined in whole body of fry after enzymatic digestion using protease type XIV with a prior derivatization step in the case of SeCys. The plant-based basal diet was found to have a much lower total Se than the fish meal-based basal diet with concentrations of 496 and 1222 μg(Se) kg(-1), respectively. Dietary Se yeast had a higher ability to raise whole body Se compared to selenite. SeMet concentration in the fry was increased only in the case of Se yeast supplementation, whereas SeCys levels were similar at the end of the feeding trial for both Se supplemented forms. The results show that the fate of dietary Se in fry is highly dependent on the form brought through supplementation and that a plant-based diet clearly benefits from Se supplementation.

Responses of growing Japanese quails that received selenium from selenium enriched kale sprout (Brassica oleracea var. alboglabra L.).

PubMed

Chantiratikul, Anut; Chinrasri, Orawan; Pakmaruek, Pornpan; Chantiratikul, Piyanete; Thosaikham, Withpol; Aengwanich, Worapol

2011-12-01

The objectives of this study were to determine the effect of selenium (Se) from Se-enriched kale sprout (Brassica oleracea var. alboglabra L.) on the performance and Se concentrations in tissues of growing Japanese quails. Two hundred quails were divided into five treatments. Each treatment consisted of four replicates and each replicate contained ten quails in a completely randomize design. The experiment was conducted for 5 weeks. The treatments were T1, control diet; T2, control diet plus 0.2 mg Se/kg from sodium selenite; T3, T4, and T5, control diet plus 0.2, 0.5, and 1.0 mg Se/kg from Se-enriched kale sprout. The results revealed that Se supplementation had no impact on feed intake, performance, and carcass characteristics of quails (p > 0.05). However, Se supplementation from both sodium selenite and Se-enriched kale sprout increased (p < 0.05) Se concentrations in the heart and breast meat of quails. Se concentrations in the liver and breast meat of quails increased (p < 0.05) with increasing Se concentration from Se-enriched kale sprout. The results indicate that Se from Se-enriched kale sprout offers no advantage over Se from sodium selenite on tissue Se concentration.

Biofortification and phytoremediation of selenium in China

PubMed Central

Wu, Zhilin; Bañuelos, Gary S.; Lin, Zhi-Qing; Liu, Ying; Yuan, Linxi; Yin, Xuebin; Li, Miao

2015-01-01

Selenium (Se) is an essential trace element for humans and animals but at high concentrations, Se becomes toxic to organisms due to Se replacing sulfur in proteins. Selenium biofortification is an agricultural process that increases the accumulation of Se in crops, through plant breeding, genetic engineering, or use of Se fertilizers. Selenium phytoremediation is a green biotechnology to clean up Se-contaminated environments, primarily through phytoextraction and phytovolatilization. By integrating Se phytoremediation and biofortification technologies, Se-enriched plant materials harvested from Se phytoremediation can be used as Se-enriched green manures or other supplementary sources of Se for producing Se-biofortified agricultural products. Earlier studies primarily aimed at enhancing efficacy of phytoremediation and biofortification of Se based on natural variation in progenitor or identification of unique plant species. In this review, we discuss promising approaches to improve biofortification and phytoremediation of Se using knowledge acquired from model crops. We also explored the feasibility of applying biotechnologies such as inoculation of microbial strains for improving the efficiency of biofortification and phytoremediation of Se. The key research and practical challenges that remain in improving biofortification and phytoremediation of Se have been highlighted, and the future development and uses of Se-biofortified agricultural products in China has also been discussed. PMID:25852703

Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review

PubMed Central

Winkel, Lenny H.E.; Vriens, Bas; Jones, Gerrad D.; Schneider, Leila S.; Pilon-Smits, Elizabeth; Bañuelos, Gary S.

2015-01-01

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels. PMID:26035246

Selenium cycling across soil-plant-atmosphere interfaces: a critical review.

PubMed

Winkel, Lenny H E; Vriens, Bas; Jones, Gerrad D; Schneider, Leila S; Pilon-Smits, Elizabeth; Bañuelos, Gary S

2015-05-29

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.

Tracking Se Assimilation and Speciation through the Rice Plant – Nutrient Competition, Toxicity and Distribution

PubMed Central

Eiche, Elisabeth; Riemann, Michael; Nick, Peter; Winkel, Lenny H. E.; Göttlicher, Jörg; Steininger, Ralph; Brendel, Rita; von Brasch, Matthias; Konrad, Gabriele; Neumann, Thomas

2016-01-01

Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations. We studied hydroponic Se uptake for 0–2500 ppb Se, potential phyto-toxicological effects of Se and the speciation of Se along the shoots and roots as a function of added Se species, concentrations and other nutrients supplied. We found that rice germinating directly in a Se environment increased plant-Se by factor 2–16, but that nutrient supplementation is required to prevent phyto-toxicity. XANES data showed that selenite uptake mainly resulted in the accumulation of organic Se in roots, but that selenate uptake resulted in accumulation of selenate in the higher part of the shoot, which is an essential requirement for Se to be transported to the grain. The amount of organic Se in the plant was positively correlated with applied Se concentration. Our results indicate that biofortification of seedlings with selenate is a successful method to increase Se levels in rice. PMID:27116220

Selenium-Containing Phycocyanin from Se-Enriched Spirulina platensis Reduces Inflammation in Dextran Sulfate Sodium-Induced Colitis by Inhibiting NF-κB Activation.

PubMed

Zhu, Chenghui; Ling, Qinjie; Cai, Zhihui; Wang, Yun; Zhang, Yibo; Hoffmann, Peter R; Zheng, Wenjie; Zhou, Tianhong; Huang, Zhi

2016-06-22

Selenium (Se) plays an important role in fine-tuning immune responses. Inflammatory bowel disease (IBD) involves hyperresponsive immunity of the digestive tract, and a low Se level might aggravate IBD progression; however, the beneficial effects of natural Se-enriched diets on IBD remain unknown. Previously, we developed high-yield Se-enriched Spirulina platensis (Se-SP) as an excellent organic nutritional Se source. Here we prepared Se-containing phycocyanin (Se-PC) from Se-SP and observed that Se-PC administration effectively reduced the extent of colitis in mouse induced by dextran sulfate sodium. Supplementation with Se-PC resulted in significant protective effects, including mitigation of body weight loss, bloody diarrhea, and colonic inflammatory damage. The anti-inflammatory effects of Se-PC supplementation were found to involve modulation of cytokines, including IL-6, TNF-α, MCP-1, and IL-10. Mechanistically, Se-PC inhibited the activation of macrophages by suppressing the nuclear translocation of NF-κB, which is involved in the transcription of these pro-inflammatory cytokines. These results together suggest potential benefits of Se-PC as a functional Se supplement to reduce the symptoms of IBD.

Reduction of elemental selenium to selenide: Experiments with anoxic sediments and bacteria that respire Se-oxyanions

USGS Publications Warehouse

Herbel, M.J.; Blum, J.S.; Oremland, R.S.; Borglin, S.E.

2003-01-01

A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe-) when supplied with Se(O). B. selenitireducens was also able to reduce selenite [Se(IV)] through Se(O) to Se(-II). Reduction of Se(O) by B.selenitireducens was more rapid in cells grown on colloidal sulfur [S(O)] or Se(IV) as their electron acceptor than for cell lines grown on fumarate. In contrast, three cultures of selenate-respiring bacteria, Sulfurospirillum barnesii, B. arsenicoselenatis, and Selenihalanaerobacter shriftii either were unable to reduce Se(O) to Se(-II) or had only a very limited capacity to achieve this reduction. Biological reduction of Se(O) to Se(-II) was observed during incubation of estuarine sediment slurries, while no such activity was noted in formalin-killed controls. The majority of the Se(-II) produced was found in the sediments as a solid precipitate of FeSe, rather than in solution as HSe-. These results demonstrate that certain anaerobic bacteria have the capacity to reduce Se(O) to Se(-II), providing a possible biological explanation for the occurrence of the selenide species in some sedimentary rocks.

Topological interface states in the natural heterostructure (PbSe)5(Bi2Se3 )6 with BiPb defects

NASA Astrophysics Data System (ADS)

Momida, Hiroyoshi; Bihlmayer, Gustav; Blügel, Stefan; Segawa, Kouji; Ando, Yoichi; Oguchi, Tamio

2018-01-01

We study theoretically the electronic band structure of (PbSe) 5(Bi2Se3 )6, which consists of an ordinary insulator PbSe and a topological insulator Bi2Se3 . The first-principles calculations show that this material has a gapped Dirac-cone energy dispersion inside the bulk, which originates from the topological states of Bi2Se3 layers encapsulated by PbSe layers. Furthermore, we calculate the band structures of (BixPb1 -xSe )5(Bi2Se3 )6 with BiPb antisite defects included in the PbSe layers. The result shows that a high density of BiPb defects can exist in real materials, consistent with the experimentally estimated x of more than 30%. The BiPb defects strongly modify the band alignment between Bi2Se3 and PbSe layers, while the topological interface states of Bi2Se3 are kept as a gapped Dirac-cone-like dispersion.

The Antiphagocytic Activity of SeM of Streptococcus equi Requires Capsule.

PubMed

Timoney, John F; Suther, Pranav; Velineni, Sridhar; Artiushin, Sergey C

2014-01-01

Resistance to phagocytosis is a crucial virulence property of Streptococcus equi (Streptococcus equi subsp. equi; Se), the cause of equine strangles. The contribution and interdependence of capsule and SeM to killing in equine blood and neutrophils were investigated in naturally occurring strains of Se. Strains CF32, SF463 were capsule and SeM positive, strains Lex90, Lex93 were capsule negative and SeM positive and strains Se19, Se1-8 were capsule positive and SeM deficient. Phagocytosis and killing of Se19, Se1-8, Lex90 and Lex93 in equine blood and by neutrophils suspended in serum were significantly (P ≤ 0.02) greater compared to CF32 and SF463. The results indicate capsule and SeM are both required for resistance to phagocytosis and killing and that the anti-phagocytic property of SeM is greatly reduced in the absence of capsule.

Reaction-diffusion-induced explosive crystallization in a metal-selenium nanometer film structure

NASA Astrophysics Data System (ADS)

Kogai, V. Ya.

2016-03-01

Experimental data for reaction-diffusion-induced explosive crystallization in a nanodimensional metal (Cu, Ag)/selenium structure are presented. It is found that after the metal layer has completely diffused into the amorphous Se film, the electrical potential rises from 0.14 to 1.21 V in the Cu(30 nm)/Se(140 nm) heterolayer and from 0.01 to 1.17 V in the Ag(30 nm)/Se(140 nm) heterolayer. The metals diffusing into the amorphous Se layer interact with Se, forming nuclei of a new phase (CuSe or Ag2Se). The intense growth of the CuSe and Ag2Se crystallization centers results in a considerable liberation of latent energy in the form of phase transformation heat and in explosive growth of CuSe and Ag2Se nanocrystalline particles. The mean size of CuSe and Ag2Se crystallites equals 25 and 50 nm, respectively.

Water selenium speciation and sediment fractionation in a California flow-through wetland system

USGS Publications Warehouse

Gao, S.; Tanii, K.K.; Peters, D.W.; Herbel, M.J.

2000-01-01

A flow-through wetland system was established in the Tulare Lake Drainage District (TLDD) in California to determine if selenium (Se) from saline irrigation drainage can be removed prior to impoundment in evaporation basins to reduce potential toxicity to waterbirds. The objective of this research was to evaluate Se speciation, accumulation, and fractionation in the waters and sediments of the newly developed wetland system. The inlet water was dominated by selenate [Se(VI), 92%], with smaller percentages of selenite [Se(IV), 5%] and organic Se [org-Se(-II), 3%]. For the outflow water, the average percentage of Se(VI) was 72% in November 1997 and 59% in February 1999. This change may be due to an increase in either residence time and/or accumulation of organic detrital matter, which may enhance Se(VI) reduction processes. Selenium accumulation, transformation, and incorporation with the solid phase were all intensified in the surface sediment (<20 cm). The highest total Se concentrations in the sediments were found in the top 5 cm and concentrations dramatically decreased with depth. Elemental Se [Se(0)], as extracted by Na2SO3, was the largest fraction (average of 46%) of the total sediment Se, followed by organic matter-associated Se (OM-Se) extracted by NaOH (average of 34%). Soluble, adsorbed, and carbonate-associated Se, as extracted by KCl, K2HPO4 (pH 8.0), and NaOAc (pH 5.0), were about 3, 10, and 3% of the total sediment Se, respectively. After establishing the wetland for 2 yr, significant Se removal from the flowing water was observed. The major sink mechanisms in the sediment are reduction to Se(0) and immobilization into the organic phase.A flow-through wetland system was established in the Tulare Lake Drainage District (TLDD) in California to determine if selenium (Se) from saline irrigation drainage can be removed prior to impoundment in evaporation basins to reduce potential toxicity to waterbirds. The objective of this research was to evaluate Se speciation, accumulation, and fractionation in the waters and sediments of the newly developed wetland system. The inlet water was dominated by selenate [Se(VI), 92%], with smaller percentages of selenite [Se(IV), 5%] and organic Se [org-Se(-II), 3%]. For the outflow water, the average percentage of Se(VI) was 72% in November 1997 and 59% in February 1999. This change may be due to an increase in either residence time and/or accumulation of organic detrital matter, which may enhance Se(VI) reduction processes. Selenium accumulation, transformation, and incorporation with the solid phase were all intensified in the surface sediment (<20 cm). The highest total Se concentrations in the sediments were found in the top 5 cm and concentrations dramatically decreased with depth. Elemental Se [Se(0)], as extracted by Na2SO3, was the largest fraction (average of 46%) of the total sediment Se, followed by organic matter-associated Se (OM-Se) extracted by NaOH (average of 34%). Soluble, adsorbed, and carbonate-associated Se, as extracted by KCl, K2HPO4 (pH 8.0), and NaOAc (pH 5.0), were about 3, 10, and 3% of the total sediment Se, respectively. After establishing the wetland for 2 yr, significant Se removal from the flowing water was observed. The major sink mechanisms in the sediment are reduction to Se(0) and immobilization into the organic phase.

Selenium-fertilized forage as a way to supplement lactating dairy cows.

PubMed

Séboussi, R; Tremblay, G F; Ouellet, V; Chouinard, P Y; Chorfi, Y; Bélanger, G; Charbonneau, É

2016-07-01

Fertilization with Se improves forage organic Se concentration, but comparisons with other forms of Se supplementation in feeding lactating dairy cows are scarce. Our objective was to compare the effect of Se-enriched forages to dietary sources of inorganic and organic Se. Digestibility, retention, and balance were assessed by measuring Se concentrations in feces, urine, milk, and blood. The resulting effect on antioxidant status and lactation performance of dairy cows was also determined. High-Se silages [1.72 mg of Se/kg of dry matter (DM)] were produced following a spring application of 2.5 kg/ha of Selcote Ultra, whereas low-Se silages (0.05 mg of Se/kg of DM) were produced in the Se-unfertilized portion of the same fields. After a 77±17 d period of Se depletion, 33 late-lactation primiparous Holstein cows were blocked and randomly assigned for 43 d to 1 of 4 experimental total mixed rations fed for ad libitum intake in an unbalanced randomized block design. Treatments consisted of 4 diets: control with low-Se silages, without Se supplement (0.12±0.04 mg of Se/kg of DM); ISe with low-Se silages and inorganic Se (0.80±0.14 mg of Se/kg of DM); YSe with low-Se silages and organic Se from yeast (0.70±0.11 mg of Se/kg of DM); and FSe with high-Se silages, without Se supplement (0.79±0.14 mg of Se/kg of DM). Organic Se, either as YSe or FSe, was more available and more effective to increase blood and milk Se concentrations than ISe. Moreover, FSe was more available than YSe, as cows fed FSe excreted 16 and 22% less Se (as percentage of intake) in feces and urine, respectively, had higher Se apparent absorption (17%), retention (37%), and balance (45%), and had greater concentration of Se in serum (16%) and milk (11%) than cows fed YSe. Antioxidant status (whole blood and plasma glutathione peroxidase, and milk thioredoxin reductase and malondialdehyde) was not affected by treatments. Dry matter intake, yield of actual, energy-corrected, and fat-corrected milk, as well as milk fat and lactose concentrations, were not affected by the dietary treatments. Cows fed ISe had lower milk protein concentration (3.44%) than cows fed YSe (3.58%) or FSe (3.51%). Cows fed Se-supplemented diets had a lower milk somatic cell count than cows fed the control diet. Results from the current study showed that the production of Se-enriched forages is an effective method to supplement dairy cows in Se as it was more available than YSe, and did not alter antioxidant status and performances of lactating dairy cows. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Meta-analysis of selenium accumulation and expression of antioxidant enzymes in chicken tissues.

PubMed

Zoidis, E; Demiris, N; Kominakis, A; Pappas, A C

2014-04-01

A meta-analysis integrating results of 40 selenium (Se) supplementation experiments that originated from 35 different controlled randomized trials was carried out in an attempt to identify significant factors that affect tissue Se accumulation in chicken. Examined factors included: Se source (12 different sources examined), type of chicken (laying hens or broilers), age of birds at the beginning of supplementation, duration of supplementation, year during which the study was conducted, sex of birds, number of chickens per treatment, method of analysis, tissue type, concentration of Se determined and Se added to feed. A correlation analysis was also carried out between tissue Se concentration and glutathione peroxidase activity. Data analysis showed that the factors significantly affecting tissue Se concentration include type of chicken (P=0.006), type of tissue (P<0.001) and the analytical method used (P=0.014). Although Se source was not found to affect tissue Se concentration (overall P>0.05), certain inorganic (sodium selenite), calcium selenite, sodium selenate and organic sources (B-Traxim Se), Se-yeast, Se-malt, Se-enriched cabbage and Se-enriched garlic as well as background Se level from feed ingredients were found to significantly affect tissue Se concentration. The Se accumulation rate (estimated as linear regression coefficient of Se concentrations to Se added to feed) discriminated between the various tissues with highest values estimated in the leg muscle and lowest in blood plasma. Correlation analysis has also shown that tissue Se concentration (pooled data) was correlated to Se added to feed (r=0.529, P<0.01, log values) and to glutathione peroxidase activity (r=0.332, P=0.0478), with the latter not being correlated with Se added to feed. Although significant factors affecting Se concentration were reported in the present study, they do not necessarily indicate the in vivo function of the antioxidant system or the level of accumulated Se as other factors, not examined in the present study, may interact at the level of trace element absorption, distribution and retention.

Novel red-emission of ternary ZnCdSe semiconductor nanocrystals

NASA Astrophysics Data System (ADS)

Chung, Shu-Ru; Wang, Kuan-Wen; Chen, Hong-Shuo; Chen, Hong-Hong

2015-02-01

The effect of chain lengths of fatty acids on the physical properties of CdSe and ZnCdSe semiconductor nanocrystals (NCs) synthesized by the colloidal chemistry procedure is investigated. The fatty acids, lauric acid (LA), and stearic acid (SA), with different lengths of carbon chains, are used to prepare CdSe and ZnCdSe NCs when hexyldecylamine (HDA) is applied as the sole surfactant. For CdSe-SA and ZnCdSe-SA, they have the same emission wavelength at 592 nm and the same particle size of 3.3 nm; however, their quantum yield (QY) is 75 and 16 %, respectively. In contrast, the emission wavelength of CdSe-LA and ZnCdSe-LA NCs is 609 and 615 nm, the particle size is about 3.5 and 4 nm under the same reaction time, and the QY of them are 33 and 59 %, respectively. The X-ray diffraction pattern shows that ZnCdSe NCs all have the wurtzite structure, and their main peaks are located between those of pure CdSe and ZnSe materials. The main phase of ZnCdSe-SA and ZnCdSe-LA is ZnSe and CdSe, respectively, implying that alloyed ZnCdSe NC can be prepared and ZnSe and CdSe phase can be promoted by SA and LA, respectively. Moreover, the QY of red-emission ZnCdSe-LA is higher than 50 %. These results suggest that the growth rate of CdSe as well as ZnCdSe NC can be enhanced by using LA as complex reagent and HDA as sole surfactant. It is expected that the reported effective synthetic strategy can be developed as a very practical, easy and not time-consuming approach to prepare red emissive NCs with high QY and high reproducibility.

Minimum Selenium Requirements Increase When Repleting Second-Generation Selenium-Deficient Rats but Are Not Further Altered by Vitamin E Deficiency.

PubMed

Sunde, Roger A; Thompson, Kevin M; Fritsche, Kevin L; Evenson, Jacqueline K

2017-05-01

Second-generation selenium-deficient weanling rats fed graded levels of dietary Se were used (a) to study the impact of initial Se deficiency on dietary Se requirements; (b) to determine if further decreases in selenoperoxidase expression, especially glutathione peroxidase 4 (Gpx4), affect growth or gross disease; and (c) to examine the impact of vitamin E deficiency on biochemical and molecular biomarkers of Se status. Rats were fed a vitamin E-deficient and Se-deficient crystalline amino acid diet (3 ng Se/g diet) or that diet supplemented with 100 μg/g all-rac-α-tocopheryl acetate and/or 0, 0.02, 0.05, 0.075, 0.1, or 0.2 μg Se/g diet as Na 2 SeO 3 for 28 days. Se-supplemented rats grew 6.91 g/day as compared to 2.17 and 3.87 g/day for vitamin E-deficient/Se-deficient and vitamin E-supplemented/Se-deficient groups, respectively. In Se-deficient rats, liver Se, plasma Gpx3, red blood cell Gpx1, liver Gpx1 and Gpx4 activities, and liver Gpx1 mRNA levels decreased to <1, <1, 21, 1.6, 49, and 11 %, respectively, of levels in rats fed 0.2 μg Se/g diet. For all biomarkers, ANOVA indicated significant effects of dietary Se, but no significant effects of vitamin E or vitamin E × Se interaction, showing that vitamin E deficiency, even in severely Se-deficient rat pups, does not result in compensatory changes in these biochemical and molecular biomarkers of selenoprotein expression. Se requirements determined in this study, however, were >50 % higher than in previous studies that started with Se-adequate rats, demonstrating that dietary Se requirements determined using initially Se-deficient animals can result in overestimation of Se requirements.

Comparative oral dose toxicokinetics of selenium compounds commonly found in selenium accumulator plants

USDA-ARS?s Scientific Manuscript database

Consumption of Se accumulator plants by livestock can result in Se intoxication. Recent research indicates that the Se forms most common in Se accumulator plants are selenate and Se-methylselenocysteine (MeSeCys). In this study the absorption, distribution, and elimination kinetics of Se in serum ...

Assessment of selenium bioavailability from naturally produced high-selenium soy foods in selenium-deficient rats.

PubMed

Yan, Lin; Reeves, Philip G; Johnson, LuAnn K

2010-10-01

We assessed the bioavailability of selenium (Se) from a protein isolate and tofu (bean curd) prepared from naturally produced high-Se soybeans. The Se concentrations of the soybeans, the protein isolate and tofu were 5.2±0.2, 11.4±0.1 and 7.4±0.1mg/kg, respectively. Male weanling Sprague-Dawley rats were depleted of Se by feeding them a 30% Torula yeast-based diet (4.1μg Se/kg) for 56 days, and then they were replenished with Se for an additional 50 days by feeding them the same diet containing 14, 24 or 30 μg Se/kg from the protein isolate or 13, 23 or 31 μg Se/kg from tofu, respectively. l-Selenomethionine (SeMet) was used as a reference. Selenium bioavailability was determined on the basis of the restoration of Se-dependent enzyme activities and tissue Se concentrations in Se-depleted rats, comparing those responses for the protein isolate and tofu to those for SeMet by using a slope-ratio method. Dietary supplementation with the protein isolate or tofu resulted in linear or log-linear, dose-dependent increases in glutathione peroxidase activities in blood and liver and in thioredoxin reductase activity in liver. Furthermore, supplementation with the protein isolate or tofu resulted in linear or log-linear, dose-dependent increases in the Se concentrations of plasma, liver, muscle and kidneys. These results indicated an overall bioavailability of approximately 101% for Se from the protein isolate and 94% from tofu, relative to SeMet. We conclude that Se from naturally produced high-Se soybeans is highly bioavailable in this model and that high-Se soybeans may be a good dietary source of Se. Published by Elsevier GmbH.

Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves

PubMed Central

Hall, Jean A.; Bobe, Gerd; Hunter, Janice K.; Vorachek, William R.; Stewart, Whitney C.; Vanegas, Jorge A.; Estill, Charles T.; Mosher, Wayne D.; Pirelli, Gene J.

2013-01-01

Selenium (Se) is an essential micronutrient in cattle, and Se-deficiency can affect morbidity and mortality. Calves may have greater Se requirements during periods of stress, such as during the transitional period between weaning and movement to a feedlot. Previously, we showed that feeding Se-fertilized forage increases whole-blood (WB) Se concentrations in mature beef cows. Our current objective was to test whether feeding Se-fertilized forage increases WB-Se concentrations and performance in weaned beef calves. Recently weaned beef calves (n = 60) were blocked by body weight, randomly assigned to 4 groups, and fed an alfalfa hay based diet for 7 wk, which was harvested from fields fertilized with sodium-selenate at a rate of 0, 22.5, 45.0, or 89.9 g Se/ha. Blood samples were collected weekly and analyzed for WB-Se concentrations. Body weight and health status of calves were monitored during the 7-wk feeding trial. Increasing application rates of Se fertilizer resulted in increased alfalfa hay Se content for that cutting of alfalfa (0.07, 0.95, 1.55, 3.26 mg Se/kg dry matter for Se application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively). Feeding Se-fertilized alfalfa hay during the 7-wk preconditioning period increased WB-Se concentrations (P Linear<0.001) and body weights (P Linear = 0.002) depending upon the Se-application rate. Based upon our results we suggest that soil-Se fertilization is a potential management tool to improve Se-status and performance in weaned calves in areas with low soil-Se concentrations. PMID:23536788

Comparative study of a new organic selenium source v. seleno-yeast and mineral selenium sources on muscle selenium enrichment and selenium digestibility in broiler chickens.

PubMed

Briens, Mickaël; Mercier, Yves; Rouffineau, Friedrich; Vacchina, Veronique; Geraert, Pierre-André

2013-08-01

Two experiments were conducted on broiler chickens to compare the effect of a new organic Se source, 2-hydroxy-4-methylselenobutanoic acid (HMSeBA; SO), with two practical Se additives, sodium selenite (SS) and Se yeast (SY). The relative bioavailability of the different Se sources was compared on muscle (pectoralis major) total Se, selenomethionine (SeMet) and selenocysteine (SeCys) concentrations and apparent digestibility of total Se (ADSe). In the first experiment, from day (d) 0 to d21, Se sources were tested at different supplied levels and compared with an unsupplemented diet (NC). No significant effects were observed on growth performance during the experimental period. However, the different Se sources and levels improved muscle Se concentration compared with the NC, with a significant source effect in the following order: SS < SY < SO (P<0·05). Seleno-amino acids speciation results for NC, SY and SO at 0·3 mg Se/kg feed indicated that muscle Se was only present as SeMet or SeCys, showing a full conversion of Se by the bird. The second experiment (d0-d24) compared SS, SY or SO at 0·3 mg Se/kg feed. The ADSe measurements carried out between d20 and d23 were 24, 46 and 49% for SS, SY and SO, respectively, with significant differences between the organic and mineral Se sources (P<0·05). These results confirmed the higher bioavailability of organic Se sources compared with the mineral source and demonstrated a significantly better efficiency of HMSeBA compared with SY for muscle Se enrichment.

Chemical and structural evolution in the Th-SeO3(2-)/SeO4(2-) system: from simple selenites to cluster-based selenate compounds.

PubMed

Xiao, Bin; Langer, Eike; Dellen, Jakob; Schlenz, Hartmut; Bosbach, Dirk; Suleimanov, Evgeny V; Alekseev, Evgeny V

2015-03-16

While extensive success has been gained in the structural chemistry of the U-Se system, the synthesis and characterization of Th-based Se structures are widely unexplored. Here, four new Th-Se compounds, α-Th(SeO3)2, β-Th(SeO3)2, Th(Se2O5)2, and Th3O2(OH)2(SeO4)3, have been obtained from mild hydrothermal or low-temperature (180-220 °C) flux conditions and were subsequently structurally and spectroscopically characterized. The crystal structures of α-Th(SeO3)2 and β-Th(SeO3)2 are based on ThO8 and SeO3 polyhedra, respectively, featuring a three-dimensional (3D) network with selenite anions filling in the Th channels along the a axis. Th(Se2O5)2 is a 3D framework composed of isolated ThO8 polyhedra interconnected by [Se2O5](2-) dimers. Th3O2(OH)2(SeO4)3 is also a 3D framework constructed by octahedral hexathorium clusters [Th6(μ3-O)4(μ3-OH)4](12+), which are interlinked by selenate groups SeO4(2-). The positions of the vibrational modes associated with both Se(IV)O3(2-) and Se(VI)O4(2-) units, respectively, were determined for four compounds, and the Raman spectra of α- and β-Th(SeO3)2 are compared and discussed in detail.

Bioavailability of particle-associated Se to the bivalve Potamocorbula amurensis

USGS Publications Warehouse

Schlekat, C.E.; Dowdle, P.R.; Lee, B.-G.; Luoma, S.N.; Oremland, R.S.

2000-01-01

Elemental selenium, Se(0), is a prevalent chemical form in sediments, but little is known about its bioavailability. We evaluated the bioavailability of two forms of Se(0) by generating radioisotopic 75Se(0) through bacterial dissimilatory reduction of 75SeO32- by pure bacterial cultures (SES) and by an anaerobic sediment microbial consortium (SED). A third form was generated by reducing 75SeO32- with ascorbic acid (AA). Speciation determinations showed that AA and SES were >90% Se(0), but SED showed a mixture of Se(0), selenoanions, and a residual fraction. Pulse-chase techniques were used to measure assimilation efficiencies (AE) of these particulate Se forms by the bivalve Potamocorbula amurensis. Mean AE values were 3 ?? 2% for AA, 7 ?? 1% for SES, and 28 ?? 15% for SED, showing that the bioavailability of reduced, particle-associated Se is dependent upon its origin. To determine if oxidative microbial processes increased Se transfer, SES 75Se(0) was incubated with an aerobic sediment microbial consortium. After 113 d of incubation, 36% of SES Se(0) was oxidized to SeO32-. Assimilation of total particulate Se was unaffected however (mean AE = 5.5%). The mean AE from the diatom Phaeodactylum tricornutum was 58 ?? 8%, verifying the importance of Se associated with biogenic particles. Speciation and AE results from SED suggest that selenoanion reduction in wetlands and estuaries produces biologically available reduced selenium.Elemental selenium, Se(0), is a prevalent chemical form in sediments, but little is known about its bioavailability. We evaluated the bioavailability of two forms of Se(0) by generating radioisotopic 75Se(0) through bacterial dissimilatory reduction of 75SeO32- by pure bacterial cultures (SES) and by an anaerobic sediment microbial consortium (SED). A third form was generated by reducing 75SeO32 with ascorbic acid (AA). Speciation determinations showed that AA and SES were > 90% Se(0), but SED showed a mixture of Se(0), selenoanions, and a residual fraction. Pulse-chase techniques were used to measure assimilation efficiencies (AE) of these particulate Se forms by the bivalve Potamocorbula amurensis. Mean AE values were 3 ?? 2% for AA, 7 ?? 1% for SES, and 28 ?? 15% for SED, showing that the bioavailability of reduced, particle-associated Se is dependent upon its origin. To determine if oxidative microbial processes increased Se transfer, SES 75Se(0) was incubated with an aerobic sediment microbial consortium. After 113 d of incubation, 36% of SES Se(0) was oxidized to SeO32-. Assimilation of total particulate Se was unaffected however (mean AE = 5.5%). The mean AE from the diatom Phaeodactylum tricornutum was 58 ?? 8%, verifying the importance of Se associated with biogenic particles. Speciation and AE results from SED suggest that selenoanion reduction in wetlands and estuaries produces biologically available reduced selenium.

Extraordinarily High Leaf Selenium to Sulfur Ratios Define ‘Se-accumulator’ Plants

PubMed Central

White, Philip J.; Bowen, Helen C.; Marshall, Bruce; Broadley, Martin R.

2007-01-01

Background and Aims Selenium (Se) and sulfur (S) exhibit similar chemical properties. In flowering plants (angiosperms) selenate and sulfate are acquired and assimilated by common transport and metabolic pathways. It is hypothesized that most angiosperm species show little or no discrimination in the accumulation of Se and S in leaves when their roots are supplied a mixture of selenate and sulfate, but some, termed Se-accumulator plants, selectively accumulate Se in preference to S under these conditions. Methods This paper surveys Se and S accumulation in leaves of 39 angiosperm species, chosen to represent the range of plant Se accumulation phenotypes, grown hydroponically under identical conditions. Results The data show that, when supplied a mixture of selenate and sulfate: (1) plant species differ in both their leaf Se ([Se]leaf) and leaf S ([S]leaf) concentrations; (2) most angiosperms show little discrimination for the accumulation of Se and S in their leaves and, in non-accumulator plants, [Se]leaf and [S]leaf are highly correlated; (3) [Se]leaf in Se-accumulator plants is significantly greater than in other angiosperms, but [S]leaf, although high, is within the range expected for angiosperms in general; and (4) the Se/S quotient in leaves of Se-accumulator plants is significantly higher than in leaves of other angiosperms. Conclusion The traits of extraordinarily high [Se]leaf and leaf Se/S quotients define the distinct elemental composition of Se-accumulator plants. PMID:17525099

Controlling factors of soil selenium distribution in a watershed in Se-enriched and longevity region of South China.

PubMed

Shao, Ya; Cai, Chongfa; Zhang, Haitao; Fu, Wei; Zhong, Xuemei; Tang, Shen

2018-05-10

Selenium (Se) is an essential nutritional element for human beings. Many studies have been conducted on concentration and distribution patterns of soil Se in low Se, Se-enriched, and selenosis areas; however, soil Se has not been systematically studied in a watershed, especially in Se-enriched longevity region and karst area in South China. This study is carried out to explore the controlling factors of Se-enriched soils in Baishou river tributary watershed, where soils are Se-enriched, and local people have the phenomenon of longevity. The area-weighted average rock Se concentration in the watershed is 0.054 mg/kg, and there are no significant differences in rock Se concentration between different strata and between different lithological rocks. The area-weighted average concentration of Se in soils (0-20 cm) is 0.80 mg/kg, and the soil Se concentration is of high level in the watershed. Soil Se concentration decreases from upstream to downstream in the watershed, and significantly correlated with elevation. Climate is the main factor causing high content of soil Se in the watershed which lacks black rock series. The difference of clastic and carbonate parent materials in soil forming process and the physical and chemical properties (pH, OM, etc.) are the main reasons for the spatial variation of Se distribution in the watershed. The research will be beneficial to the development and utilization of Se-enriched soil in Se-enriched area.

The Effect of Risk Factors on the Levels of Chemical Elements in the Tibial Plateau of Patients with Osteoarthritis following Knee Surgery.

PubMed

Lanocha-Arendarczyk, Natalia; Kosik-Bogacka, Danuta Izabela; Prokopowicz, Adam; Kalisinska, Elzbieta; Sokolowski, Sebastian; Karaczun, Maciej; Zietek, Pawel; Podlasińska, Joanna; Pilarczyk, Bogumila; Tomza-Marciniak, Agnieszka; Baranowska-Bosiacka, Irena; Gutowska, Izabela; Safranow, Krzysztof; Chlubek, Dariusz

2015-01-01

The aim of this study was to evaluate the aforementioned chemical elements in tibial plateau samples obtained during knee arthroplasty. The gender-specific analysis of chemical element levels in the bone samples revealed that there were statistically significant differences in the concentration of Pb and Se/Pb ratio. The contents of elements in the tibial plateau in the patients with osteoarthritis (OA) can be arranged in the following descending order: F(-) > K > Zn > Fe > Sr > Pb > Mn > Se > Cd > THg. We observed statistical significant effects of environmental factors including smoking, seafood diet, and geographical distribution on the levels of the elements in tibial bone. Significant positive correlation coefficients were found for the relationships K-Cd, Zn-Sr, Zn-F(-), THg-Pb, Pb-Cd, Se-Se/Pb, Se-Se/Cd, Se/Pb-Se/Cd, Pb-Cd/Ca, Cd-Cd/Ca, and F(-)-F(-)/Ca·1000. Significant negative correlations were found for the relationships THg-Se/Pb, Pb-Se/Pb, Cd-Se/Pb, K-Se/Cd, Pb-Se/Cd, Cd-Se/Cd, THg-Se/THg, Pb-Se/THg, Se-Pb/Cd, Zn-Cd/Ca, and Se/Cd-Cd/Ca. The results reported here may provide a basis for establishing reference values for the tibial plateau in patients with OA who had undergone knee replacement surgery. The concentrations of elements in the bone with OA were determined by age, presence of implants, smoking, fish and seafood diet, and sport activity.

Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whanger, P.D.; Robinson, M.F.; Feldman, E.B.

1986-03-01

The majority of erythrocyte (RBC) selenium (Se) is associated with glutathione peroxidase (GPx) in animals, but most of it is with hemoglobin (Hb) in human RBCs. Dietary forms of Se may influence this distribution since a rat study showed that selenite promoted the deposition of Se in GPx but selenomethionine (SeMet) resulted in greater amounts with Hb. Three different populations of people were chosen to investigate some possible reasons for the Se distribution in human RBC proteins. An average of 12% of the RBC Se (0.71 ng Se/mg Hb) was associated with GPx in people living in Oregon, but nearlymore » 30% of the Se was associated with GPx in RBC (0.26 ng Se/mg Hb) from New Zealanders. Georgia residents with low RBC Se levels (0.35 ng Se/mg Hb) had 38% of the Se associated with GPx as compared to 29% for those with higher RBC levels (0.56 ng Se/mg Hb). In a third group of people the amount of Se tended to be higher in RBC GPx from non-vegetarian OSU students than from vegetarians. The predominant form of Se in meat appears to be selenocysteine, which is metabolized similarly to selenite, and presumably contributes to this difference since many plant foods contain Se as SeMet. These are examples of many possible factors affecting the relative distribution of Se in human RBC proteins.« less

Bis(dicyclohexylselenophosphinyl)selenide, [Cy2P(Se)]2Se: Synthesis, molecular structure and application for self-assembly of a tetrahedral Cu(I) cluster

NASA Astrophysics Data System (ADS)

Artem'ev, Alexander V.; Doronina, Evgeniya P.; Bagryanskaya, Irina Yu; Klyba, Lyudmila V.

2018-05-01

The molecular structure of the selenides of [R2P(Se)]2Se type has been systematically studied on example of bis(dicyclohexylselenophosphinyl)selenide, [Cy2P(Se)]2Se. This selenide has been synthesized in 65% yield by oxidation of Cy2PH with elemental selenium in 1:2 M ratio. Its structure has been investigated by X-ray diffractometry (XRD), NMR, FT-IR and MALDI-TOF/MS techniques. In the solid, the Se1sbnd Psbnd Se2sbnd Psbnd Se3 chain of (Cy2P = Se)2Se molecule adopts a syn-anti conformation with the Se1sbnd Psbnd Se2sbnd P and Psbnd Se2sbnd Psbnd Se3 torsion angles of -179.64 (3)° and 4.69 (4)°. The vibrational band assignments, performing at B3LYP/6-311++G (d,p) theory level, are in a good agreement with the experimental FT-IR frequencies. The synthetic utility of the prepared selenide has been exemplified by its reaction with CuCl2 resulted in the formation of [Cu4(Se2PCy2)4] cluster in 53% yield. The structure of latter is formed by a Cu4 tetrahedron, wherein each triangular face is bridged by a [Se2PCy2] ligand in a trimetallic triconnective (μ2, μ1) pattern.

Anion-Anion Bonding and Topology in Ternary Iridium Seleno-Stannides.

PubMed

Trump, Benjamin A; Tutmaher, Jake A; McQueen, Tyrel M

2015-12-21

The synthesis and physical properties of two new and one known Ir-Sn-Se compound are reported. Their crystal structures are elucidated with transmission electron microscopy and powder X-ray diffraction. IrSn0.45Se1.55 is a pyrite phase which consists of tilted corner-sharing IrX6 octahedra with randomly distributed (Sn-Se)(4-) and (Se-Se)(2-) dimers. Ir2Sn3Se3 is a known trigonally distorted skutterudite that consists of cooperatively tilted corner-sharing IrSn3Se3 octahedra with ordered (Sn-Se)2(4-) tetramers. Ir2SnSe5 is a layered, distorted β-MnO2 (pyrolusite) structure consisting of a double IrSe6 octrahedral row, corner sharing in the a direction and edge sharing in the b direction. This distorted pyrolusite contains (Se-Se)(2-) dimers and Se(2-) anions, and each double row is "capped" with a (Sn-Se)n polymeric chain. Resistivity, specific heat, and magnetization measurements show that all three have insulating and diamagnetic behavior, indicative of low-spin 5d(6) Ir(3+). Electronic structure calculations on Ir2Sn3Se3 show a single, spherical, nonspin-orbit split valence band and suggest that Ir2Sn3Se3 is topologically nontrivial under tensile strain due to inversion of Ir-d and Se-p states.

Selenium speciation in seleniferous agricultural soils under different cropping systems using sequential extraction and X-ray absorption spectroscopy.

PubMed

Qin, Hai-Bo; Zhu, Jian-Ming; Lin, Zhi-Qing; Xu, Wen-Po; Tan, De-Can; Zheng, Li-Rong; Takahashi, Yoshio

2017-06-01

Selenium (Se) speciation in soil is critically important for understanding the solubility, mobility, bioavailability, and toxicity of Se in the environment. In this study, Se fractionation and chemical speciation in agricultural soils from seleniferous areas were investigated using the elaborate sequential extraction and X-ray absorption near-edge structure (XANES) spectroscopy. The speciation results quantified by XANES technique generally agreed with those obtained by sequential extraction, and the combination of both approaches can reliably characterize Se speciation in soils. Results showed that dominant organic Se (56-81% of the total Se) and lesser Se(IV) (19-44%) were observed in seleniferous agricultural soils. A significant decrease in the proportion of organic Se to the total Se was found in different types of soil, i.e., paddy soil (81%) > uncultivated soil (69-73%) > upland soil (56-63%), while that of Se(IV) presented an inverse tendency. This suggests that Se speciation in agricultural soils can be significantly influenced by different cropping systems. Organic Se in seleniferous agricultural soils was probably derived from plant litter, which provides a significant insight for phytoremediation in Se-laden ecosystems and biofortification in Se-deficient areas. Furthermore, elevated organic Se in soils could result in higher Se accumulation in crops and further potential chronic Se toxicity to local residents in seleniferous areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparing functional metabolic effects of marginal and sufficient selenium supply in sheep.

PubMed

Humann-Ziehank, Esther; Renko, Kostja; Mueller, Andreas S; Roehrig, Petra; Wolfsen, Jacqueline; Ganter, Martin

2013-10-01

This study was performed to characterise key data of long-term ovine Se metabolism and to work out the best biomarker of Se status. An upgrade from marginal (<0.05 mg Se/kg diet, 'Se-') to sufficient (0.2mg Se/kg diet, 'Se+') nutritional Se supply using sodium selenite was monitered biweekly by analysing Se concentration, glutathione peroxidase (Gpx) activity and routine biochemistry in blood/serum over 2 years. Se, Cu, Zn, cytosolic Gpx and thioredoxin reductase (TrxR) activity were measured in the liver (biopsies/post-mortem). Se, Gpx, TrxR, glutathione-S-transferase-alpha (aGST) and iodothyronine deiodinase (Dio1) were analysed in the kidney, heart muscle and thyroid. Relative mRNA expression of hepatic aGST1 and Gpx1 was determined. Improvement of Se supply strongly increased serum and liver Se concentration within 10 and 20 days, respectively followed by a plateau. Whereas the achievement of a maximum whole blood Gpx activity was reached after 3 months, serum Gpx3 activity increased with high variations. Hepatic Gpx activity reached a maximum during days 100-200, decreasing thereafter. Distinct group differences in Se and cytosolic Gpx activity were evident in all organs (except Se in kidney). TrxR and Dio1 activity was affected only in the liver. The Se- sheep showed an ongoing decrease in serum Se concentration within 2 years, whereas liver Se remained almost unaffected. High relative Gpx1 mRNA expression in the Se+ group was consensual to high hepatic Gpx activity. Relative mRNA expression of hepatic aGST1 was higher in the Se- sheep. Clinical signs and abnormalities in routine biochemistry were absent. In summary, the best biomarker of Se deprivation and nutritional Se upgrade, respectively was Se in serum. Moreover, hepatic Se concentrations reliably reflected the upgrade of Se supply within days. Whole blood Gpx reacts slowly depending on newly formed erythrocytes restricting its diagnostic use. Vital organs are affected by Se deficiency due to a decrease of cytosolic Gpx activity attenuating the antioxidative system. Cellular up-regulation of aGST1 mRNA expression in the Se- group is assumed to partially compensate for the decreased antioxidant defence due to a loss in Gpx activity. This sheep model appears advantageous for long-term studies on sub-clinical metabolic effects in experimental modifiable nutritional Se supply. Copyright © 2013 Elsevier GmbH. All rights reserved.

Biofortification of UK food crops with selenium.

PubMed

Broadley, Martin R; White, Philip J; Bryson, Rosie J; Meacham, Mark C; Bowen, Helen C; Johnson, Sarah E; Hawkesford, Malcolm J; McGrath, Steve P; Zhao, Fang-Jie; Breward, Neil; Harriman, Miles; Tucker, Mark

2006-05-01

Se is an essential element for animals. In man low dietary Se intakes are associated with health disorders including oxidative stress-related conditions, reduced fertility and immune functions and an increased risk of cancers. Although the reference nutrient intakes for adult females and males in the UK are 60 and 75 microg Se/d respectively, dietary Se intakes in the UK have declined from >60 microg Se/d in the 1970s to 35 microg Se/d in the 1990s, with a concomitant decline in human Se status. This decline in Se intake and status has been attributed primarily to the replacement of milling wheat having high levels of grain Se and grown on high-Se soils in North America with UK-sourced wheat having low levels of grain Se and grown on low-Se soils. An immediate solution to low dietary Se intake and status is to enrich UK-grown food crops using Se fertilisers (agronomic biofortification). Such a strategy has been adopted with success in Finland. It may also be possible to enrich food crops in the longer term by selecting or breeding crop varieties with enhanced Se-accumulation characteristics (genetic biofortification). The present paper will review the potential for biofortification of UK food crops with Se.

Chemical form of selenium affects its uptake, transport, and glutathione peroxidase activity in the human intestinal Caco-2 cell model.

PubMed

Zeng, Huawei; Jackson, Matthew I; Cheng, Wen-Hsing; Combs, Gerald F

2011-11-01

Determining the effect of selenium (Se) chemical form on uptake, transport, and glutathione peroxidase activity in human intestinal cells is critical to assess Se bioavailability at nutritional doses. In this study, we found that two sources of L-selenomethionine (SeMet) and Se-enriched yeast each increased intracellular Se content more effectively than selenite or methylselenocysteine (SeMSC) in the human intestinal Caco-2 cell model. Interestingly, SeMSC, SeMet, and digested Se-enriched yeast were transported at comparable efficacy from the apical to basolateral sides, each being about 3-fold that of selenite. In addition, these forms of Se, whether before or after traversing from apical side to basolateral side, did not change the potential to support glutathione peroxidase (GPx) activity. Although selenoprotein P has been postulated to be a key Se transport protein, its intracellular expression did not differ when selenite, SeMSC, SeMet, or digested Se-enriched yeast was added to serum-contained media. Taken together, our data show, for the first time, that the chemical form of Se at nutritional doses can affect the absorptive (apical to basolateral side) efficacy and retention of Se by intestinal cells; but that, these effects are not directly correlated to the potential to support GPx activity.

Dietary selenium requirements based on tissue selenium concentration and glutathione peroxidase activities in old female rats.

PubMed

Sunde, Roger A; Thompson, Kevin M

2009-01-01

Dietary nutrient requirements for older animals have been studied far less than have requirements for young growing animals. To determine dietary selenium (Se) requirements in old rats, we fed female weanling rats a Se-deficient diet (0.007 microg Se/g) or supplemented rats with graded levels of dietary Se (0-0.3 microg Se/g) as Na(2)SeO(3) for 52 weeks. At no point did Se deficiency or level of Se supplementation have a significant effect (P>0.05) on growth. To determine Se requirements, Se response curves were determined for 7 Se-dependent parameters. We found that minimum dietary Se requirements in year-old female rats were at or below 0.05 microg Se/g diet based on liver Se, red blood cell glutathione peroxidase (Gpx1) activity, plasma Gpx3 activity, liver and kidney Gpx1 activity, and liver and kidney Gpx4 activity. In conclusion, this study found that dietary Se requirements in old female rats were decreased at least 50% relative to requirements found in young, rapidly growing female rats. Collectively, this indicates that the homeostatic mechanisms related to retention and maintenance of Se status are still fully functional in old female rats.

Selenium distribution in the Chinese environment and its relationship with human health: A review.

PubMed

Dinh, Quang Toan; Cui, Zewei; Huang, Jie; Tran, Thi Anh Thu; Wang, Dan; Yang, Wenxiao; Zhou, Fei; Wang, Mengke; Yu, Dasong; Liang, Dongli

2018-03-01

This paper reviewed the Se in the environment (including total Se in soil, water, plants, and food), the daily Se intake and Se content in human hair were also examined to elucidate Se distribution in the environment and its effects on human health in China. Approximately 51% of China is Se deficiency in soil, compared with 72% in the survey conducted in 1989. Low Se concentrations in soil, water, plants, human diet and thus human hair were found in most areas of China. The only significant difference was observed between Se-rich and Se-excessive areas for Se contents in water, staple cereal, vegetables, fruits, and animal-based food, no remarkable contrast was found among other areas (p>0.05). This study also demonstrated that 39-61% of Chinese residents have lower daily Se intakes according to WHO/FAO recommended value (26-34μg/day). Further studies should focus on thoroughly understanding the concentration, speciation, and distribution of Se in the environment and food chain to successfully utilize Se resources, remediate Se deficiency, and assess the Se states and eco-effects on human health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Macro- and microscale investigation of selenium speciation in Blackfoot river, Idaho sediments.

PubMed

Oram, Libbie L; Strawn, Daniel G; Marcus, Matthew A; Fakra, Sirine C; Möller, Gregory

2008-09-15

The transport and bioavailability of selenium in the environment is controlled by its chemical speciation. However, knowledge of the biogeochemistry and speciation of Se in streambed sediment is limited. We investigated the speciation of Se in sediment cores from the Blackfoot River (BFR), Idaho using sequential extractions and synchrotron-based micro-X-ray fluorescence (micro-SXRF). We collected micro-SXRF oxidation state maps of Se in sediments, which had not been done on natural sediment samples. Selective extractions showed that most Se in the sediments is present as either (1) nonextractable Se or (2) base extractable Se. Results from micro-SXRF showed three defined species of Se were present in all four samples: Se(-II,O), Se(IV), and Se(VI). Se(-II,O) was the predominant species in samples from one location, and Se(IV) was the predominant species in samples from a second location. Results from both techniques were consistent, and suggested that the predominant species were Se(-II) species associated with recalcitrant organic matter, and Se(IV) species tightly bound to organic materials. This information can be used to predict the biogeochemical cycling and bioavailability of Se in streambed sediment environments.

Size effect of elemental selenium nanoparticles (Nano-Se) at supranutritional levels on selenium accumulation and glutathione S-transferase activity.

PubMed

Peng, Dungeng; Zhang, Jinsong; Liu, Qingliang; Taylor, Ethan Will

2007-10-01

It has been shown that 36 nm Nano-Se has lower toxicity than selenite or selenomethionine, but these forms of selenium (Se) all possess similar ability to increase selenoenzyme levels. The size of nanoparticles plays an important role in their biological activity: as expected, 5-200 nm Nano-Se can directly scavenge free radicals in vitro in a size-dependent fashion. However, in Se-deficient cells and Se-deficient mice, the size effect of Nano-Se on increasing selenoenzymes and liver Se disappears unexpectedly. We hypothesize that under conditions of Se deficiency, the avidity of Se uptake mechanisms may be increased to maintain the biosynthesis of selenoenzymes, which are fundamental for redox homeostasis. This increased avidity may override the potential advantage of small size Nano-Se seen under Se-replete conditions, thereby eliminating the size effect. Once selenoenzymes have been saturated, Se uptake mechanisms may downregulate; accordingly, the size effect of Nano-Se can then reappear. To test this hypothesis, Se-deficient mice were administered either 36 or 90 nm Nano-Se at supranutritional doses, in both a short-term model and a single-dose model. Under these conditions, Nano-Se showed a size effect on Se accumulation and glutathione S-transferase (GST) activity. A size effect of Nano-Se was found in 15 out of 18 total comparisons between sizes at the same dose and time in the two models. Furthermore, the magnitude of the size effect was more prominent on Se accumulation than on GST activity. GST is strictly regulated by transcriptional and translational mechanisms, so its increase in activity normally does not exceed 3-fold. In contrast, the homeostasis of Se accumulation is not as tightly controlled. In the present experiments, GST activity had reached or was approaching saturation, but liver Se was far below saturation. Therefore, our results strongly suggest that the saturation profile of the tested biomarker has an impact on the size effect of Nano-Se. Since both GST and small molecular weight selenocompounds accumulated in vivo are important intermediates for chemoprevention by Se, our results also suggest that Nano-Se should be most effective as a chemopreventive agent at smaller particle size.

Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi.

PubMed

Tran, Thi Anh Thu; Dinh, Quang Toan; Cui, Zeiwei; Huang, Jie; Wang, Dan; Wei, Tianjiao; Liang, Dongli; Sun, Xin; Ning, Ping

2018-01-01

Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se 4+ and Se 6+ ) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl 2 ) and selenite (Na 2 SeO 3 ) or selenate (Na 2 SeO 4 ) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg I R values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), I R values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the I R indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se 4+ or Se 6+ ). Copyright © 2017 Elsevier Inc. All rights reserved.

Selenium biofortification of broccoli and carrots grown in soil amended with Se-enriched hyperaccumulator Stanleya pinnata.

PubMed

Bañuelos, Gary S; Arroyo, Irvin; Pickering, Ingrid J; Yang, Soo In; Freeman, John L

2015-01-01

Amending soils with Se-hyperaccumulator plant derived sources of selenium (Se) may be useful for increasing the Se content in food crops in Se-deficient regions of the world. In this study we evaluated total Se and the different chemical species of Se in broccoli and carrots grown in soils amended with ground shoots of the Se-hyperaccumulator Stanleyapinnata. With increasing application rates of S. pinnata, total plant Se concentrations increased to nutritionally ideal levels inside edible parts. Selenium compounds in aqueous extracts were analyzed by SAX-HPLC-ICPMS and identified as a variety of mainly organic-Se forms. Together with bulk Se K-edge X-ray absorption near-edge structure (XANES) analysis performed on broccoli florets, carrot roots and shoots, dried ground S. pinnata, and the amended soil at post-plant, we demonstrate that Se-enriched S. pinnata is valuable as a soil amendment for enriching broccoli and carrots with healthful forms of organic-Se. Published by Elsevier Ltd.

Selenium supplementation has beneficial and detrimental effects on immunity to influenza vaccine in older adults.

PubMed

Ivory, Kamal; Prieto, Elena; Spinks, Caroline; Armah, Charlotte N; Goldson, Andrew J; Dainty, Jack R; Nicoletti, Claudio

2017-04-01

Mortality resulting from influenza (flu) virus infections occurs primarily in the elderly through declining immunity. Studies in mice have suggested beneficial effects of selenium (Se) supplementation on immunity to flu but similar evidence is lacking in humans. A dietary intervention study was therefore designed to test the effects of Se-supplementation on a variety of parameters of anti-flu immunity in healthy subjects aged 50-64 years. A 12-week randomized, double-blinded, placebo-controlled clinical trial (ClinicalTrials.govNCT00279812) was undertaken in six groups of individuals with plasma Se levels <110 ng/mL. Four groups were given daily capsules of yeast enriched with 0 μg Se/day (SeY-0/d; n = 20), 50 μg Se/d (SeY-50/d; n = 18), 100 μg Se/d (SeY-100/d; n = 21) or 200 μg Se/d (SeY-200/d; n = 23). Two groups were given onion-containing meals with either <1 μg Se/d (SeO-0/d; n = 17) or 50 μg Se/d (SeO-50/d; n = 18). Flu vaccine was administrated at week 10 and immune parameters were assessed until week 12. Primary study endpoints were changes in cellular and humoral immune responses. Supplementation with SeY and SeO affected different aspects of cellular immunity. SeY increased Tctx-ADCC cell counts in blood (214%, SeY-100/d) before flu vaccination and a dose-dependent increase in T cell proliferation (500%, SeY-50/100/200/d), IL-8 (169%, SeY-100/d) and IL-10 (317%, SeY-200/d) secretion after in vivo flu challenge. Positive effects were contrasted by lower granzyme B content of CD8 cells (55%, SeY-200/d). SeO (Se 50 μg/d) also enhanced T cell proliferation after vaccination (650%), IFN-γ (289%), and IL-8 secretion (139%), granzyme (209%) and perforin (190%) content of CD8 cells but inhibited TNF-α synthesis (42%). Onion on its own reduced the number of NKT cells in blood (38%). These effects were determined by comparison to group-specific baseline yeast or onion control groups. Mucosal flu-specific antibody responses were unaffected by Se-supplementation. Se-supplementation in healthy human adults with marginal Se status resulted in both beneficial and detrimental effects on cellular immunity to flu that was affected by the form of Se, supplemental dose and delivery matrix. These observations call for a thorough evaluation of the risks and benefits associated with Se-supplementation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Complexation of Sn{sub 2}Se{sub 6} with lanthanide(III) centers influenced by ethylene polyamines: Solvothermal syntheses, crystal structures, and optical properties of lanthanide selenidostannates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Chunying; Wang, Fang; Chen, Ruihong

Lanthanide selenidostannates (H{sub 3}O){sub n}[Ce(tepa)(μ-1κ{sup 2}:2κ{sup 2}-Sn{sub 2}Se{sub 6})]{sub n} (1), [(Yb(tepa)(μ-OH)){sub 2}(μ-1κ:2κ-Sn{sub 2}Se{sub 6})]{sub n}·nH{sub 2}O (2), [Htrien]{sub 2}[(Ln(trien)(tren)){sub 2}(μ-1κ:2κ-Sn{sub 2}Se{sub 6})][Sn{sub 2}Se{sub 6}] (Ln=Ce(3), Nd(4)) and [(Yb(dien){sub 2}){sub 2}(μ-OH){sub 2}]Sn{sub 2}Se{sub 6} (5) were solvothermally prepared in different ethylene polyamines. The Sn{sub 2}Se{sub 6} unit connects [Ce(tepa)]{sup 3+} and [(Yb(tepa)(μ-OH)){sub 2}]{sup 4+} fragments with tetradentate μ-1κ{sup 2}Se{sup 1},Se{sup 2}:2κ{sup 2}Se{sup 5},Se{sup 6} and bidentate μ-1κSe{sup 1}:2κSe{sup 5} bridging coordination modes in tepa, to form polymers 1 and 2, respectively. It joins two [Ln(trien)(tren)]{sup 3+} fragments as a μ-1κSe{sup 1}:2κSe{sup 5} ligand to form binuclear complexes 3 and 4more » in trien. Unlike the Sn{sub 2}Se{sub 6} units in 1–4 that bind with Ln(III) centers as Se-donor ligands, the Sn{sub 2}Se{sub 6} unit in 5 exists as a discrete ion. The syntheses of 1–5 show that the ethylene polyamines play an important role in the complexation of Sn{sub 2}Se{sub 6} ligand with Ln(III) centers. Compounds 1–5 exhibit optical band gaps in the range of 2.09–2.42 eV, which are influenced by the complexation of Sn{sub 2}Se{sub 6} with Ln(III) centers. - Graphical abstract: New lanthanide complexes concerning the Sn{sub 2}Se{sub 6} ligand were solvothermally prepared, and the effect of ethylene polyamines on the complexation of Sn{sub 2}Se{sub 6} with Ln(III) centers are observed. Highlights: • Lanthanide complexes concerning the selenidostannates have been solvothermally prepared in different ethylene polyamines. • A tetradentate μ-1κ{sup 2}Se{sup 1},Se{sup 2}:2κ{sup 2}Se{sup 5},Se{sup 6} and a bidentate μ-1κSe{sup 1}:2κSe{sup 5} bridging coordination modes for the Sn{sub 2}Se{sub 6} ligand is obtained. • The complexation of the Sn{sub 2}Se{sub 6} ligand with Ln(III) centers are influenced by the ethylene polyamines.« less

Facile fabrication of CNTs@C@MoSe2@Se hybrids with amorphous structure for high performance anode in lithium-ion batteries.

PubMed

Jin, Rencheng; Cui, Yuming; Wang, Qingyao; Li, Guihua

2017-12-15

Amorphous MoSe 2 and Se anchored on amorphous carbon coated multiwalled carbon nanotubes (CNTs@C@MoSe 2 @Se) have been synthesized by a facile solvothermal strategy. The one dimensional CNTs@C@MoSe 2 @Se can effectively buffer the volume variation, prohibit the aggregation and facilitate electron and ion transport throughout the electrode. Furthermore, the combination of MoSe 2 and Se also provides buffer spaces for the volumetric change during cycling. Thus, the obtained CNTs@C@MoSe 2 @Se hybrids display the enhanced cycle stability and excellent high rate capacity. The reversible capacity of 1010mAhg -1 can be achieved after 100 cycles at the current density of 0.1Ag -1 . Even after 500 cycles, a reversible capacity of 508mAhg -1 is still retained at 5Ag -1 . Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanistic investigations of Se(VI) treatment in anoxic groundwater using granular iron and organic carbon: an EXAFS study.

PubMed

Gibson, Blair D; Blowes, David W; Lindsay, Matthew B J; Ptacek, Carol J

2012-11-30

The removal of aqueous Se(VI) from a simulated groundwater by granular iron (GI), organic carbon (OC), and a mixture of these reactive materials (GI-OC) was evaluated in laboratory batch experiments. The experiments were performed under anoxic conditions to simulate subsurface treatment. A total reaction time of 120 h (5 d) was chosen to investigate the rapid changes in speciation occurring over reaction times that are reasonable for permeable reactive barrier (PRB) systems. After 120 h, concentrations of Se decreased by >90% in the GI system, 15% in the OC system and 35% in the GI-OC mixture. Analysis of the materials after contact with Se using synchrotron-radiation based X-ray absorption spectroscopy (XAS) indicated the presence of Se(IV) and Se(0) on the margins of GI grains after 6h with evidence of SeO and SeSe bonding, whereas Se(VI) was not observed. After 72 h, Se(0) was the only form of Se present in the GI experiments. In the OC batches, the XAS analysis indicated binding consistent with sorption of aqueous Se(VI) onto the OC with only minor reduction to Se(IV) and Se(0) after 120 h. Selenium XAS spectra collected for the GI-OC mixture were consistent with spectra for Se(IV) and Se(0) on both the margins of GI grains and OC particles, suggesting that the presence of dissolved Fe may have mediated the reduction of sorbed Se(VI). The results suggest that the application of granular Fe is effective at inducing aqueous Se removal in anoxic conditions through reductive precipitation processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Selecting Lentil Accessions for Global Selenium Biofortification.

PubMed

Thavarajah, Dil; Abare, Alex; Mapa, Indika; Coyne, Clarice J; Thavarajah, Pushparajah; Kumar, Shiv

2017-08-26

The biofortification of lentil ( Lens culinaris Medikus.) has the potential to provide adequate daily selenium (Se) to human diets. The objectives of this study were to (1) determine how low-dose Se fertilizer application at germination affects seedling biomass, antioxidant activity, and Se uptake of 26 cultivated lentil genotypes; and (2) quantify the seed Se concentration of 191 lentil wild accessions grown in Terbol, Lebanon. A germination study was conducted with two Se treatments [0 (control) and 30 kg of Se/ha] with three replicates. A separate field study was conducted in Lebanon for wild accessions without Se fertilizer. Among cultivated lentil accessions, PI533690 and PI533693 showed >100% biomass increase vs. Se addition significantly increased seedling Se uptake, with the greatest uptake (6.2 µg g -1 ) by PI320937 and the least uptake (1.1 µg g -1 ) by W627780. Seed Se concentrations of wild accessions ranged from 0 to 2.5 µg g -1 ; accessions originating from Syria (0-2.5 µg g -1 ) and Turkey (0-2.4 µg g -1 ) had the highest seed Se. Frequency distribution analysis revealed that seed Se for 63% of accessions was between 0.25 and 0.75 µg g -1 , and thus a single 50 g serving of lentil has the potential to provide adequate dietary Se (20-60% of daily recommended daily allowance). As such, Se application during plant growth for certain lentil genotypes grown in low Se soils may be a sustainable Se biofortification solution to increase seed Se concentration. Incorporating a diverse panel of lentil wild germplasm into Se biofortification programs will increase genetic diversity for effective genetic mapping for increased lentil seed Se nutrition and plant productivity.

Selecting Lentil Accessions for Global Selenium Biofortification

PubMed Central

Thavarajah, Dil; Abare, Alex; Mapa, Indika; Coyne, Clarice J.; Thavarajah, Pushparajah; Kumar, Shiv

2017-01-01

The biofortification of lentil (Lens culinaris Medikus.) has the potential to provide adequate daily selenium (Se) to human diets. The objectives of this study were to (1) determine how low-dose Se fertilizer application at germination affects seedling biomass, antioxidant activity, and Se uptake of 26 cultivated lentil genotypes; and (2) quantify the seed Se concentration of 191 lentil wild accessions grown in Terbol, Lebanon. A germination study was conducted with two Se treatments [0 (control) and 30 kg of Se/ha] with three replicates. A separate field study was conducted in Lebanon for wild accessions without Se fertilizer. Among cultivated lentil accessions, PI533690 and PI533693 showed >100% biomass increase vs. controls. Se addition significantly increased seedling Se uptake, with the greatest uptake (6.2 µg g−1) by PI320937 and the least uptake (1.1 µg g−1) by W627780. Seed Se concentrations of wild accessions ranged from 0 to 2.5 µg g−1; accessions originating from Syria (0–2.5 µg g−1) and Turkey (0–2.4 µg g−1) had the highest seed Se. Frequency distribution analysis revealed that seed Se for 63% of accessions was between 0.25 and 0.75 µg g−1, and thus a single 50 g serving of lentil has the potential to provide adequate dietary Se (20–60% of daily recommended daily allowance). As such, Se application during plant growth for certain lentil genotypes grown in low Se soils may be a sustainable Se biofortification solution to increase seed Se concentration. Incorporating a diverse panel of lentil wild germplasm into Se biofortification programs will increase genetic diversity for effective genetic mapping for increased lentil seed Se nutrition and plant productivity. PMID:28846602

Selenium-Induced Toxicity Is Counteracted by Sulfur in Broccoli (Brassica oleracea L. var. italica).

PubMed

Tian, Ming; Hui, Maixia; Thannhauser, Theodore W; Pan, Siyi; Li, Li

2017-01-01

Selenium (Se) is an essential micronutrient for humans. Increasing Se content in food crops offers an effective approach to enhance the consumption of Se in human diets. A thoroughly understanding of the effects of Se on plant growth is important for Se biofortification in food crops. Given that Se is an analog of sulfur (S) and can be toxic to plants, its effect on plant growth is expected to be greatly affected by S nutrition. However, this remains to be further understood. Here, we evaluated the influence of Se treatments on broccoli ( Brassica oleracea L. var. italica ) growth when S was withheld from the growth nutrient solution. We found that Se was highly toxic to plants when S nutrition was poor. In contrast to Se treatments with adequate S nutrition that slightly reduced broccoli growth, the same concentration of Se treatments without S supplementation dramatically reduced plant sizes. Higher Se toxicity was observed with selenate than selenite under low S nutrition. We examined the bases underlying the toxicity. We discovered that the high Se toxicity in low S nutrition was specifically associated with an increased ratio of Se in proteins verse total Se level, enhanced generation of reactive oxygen species, elevated lipid peroxidation causing increased cell membrane damage, and reduced antioxidant enzyme activities. Se toxicity could be counteracted with increased supplementation of S, which is likely through decreasing non-specific integration of Se into proteins and altering the redox system. The present study provides information for better understanding of Se toxicity and shows that adequate S nutrition is important to prevent Se toxicity during biofortification of crops by Se fertilization.

Recrystallization method to selenization of thin-film Cu(In,Ga)Se.sub.2 for semiconductor device applications

DOEpatents

Albin, David S.; Carapella, Jeffrey J.; Tuttle, John R.; Contreras, Miguel A.; Gabor, Andrew M.; Noufi, Rommel; Tennant, Andrew L.

1995-07-25

A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550.degree. C.) at which Cu(In,Ga)Se.sub.2 is solid and Cu.sub.x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu.sub.x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu.sub.x (In,Ga).sub.y Se.sub.z. The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450.degree. C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100.degree. C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.

Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts

NASA Astrophysics Data System (ADS)

Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

2013-09-01

Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields.Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields. Electronic supplementary information (ESI) available: Fig. S1-S8 and Table S1. See DOI: 10.1039/c3nr03601d

Influence of defects and doping on phonon transport properties of monolayer MoSe2

NASA Astrophysics Data System (ADS)

Yan, Zhequan; Yoon, Mina; Kumar, Satish

2018-07-01

The doping of monolayer MoSe2 by tungsten (W) can suppress the Se vacancy concentration, but how doping and resulting change in defect concentration can tune its thermal properties is not understood yet. We use first-principles density functional theory (DFT) along with the phonon Boltzmann transport equation (BTE) to study the phonon transport properties of pristine MoSe2 and W doped MoSe2 with and without the presence of Se vacancies. We found that for samples without Se vacancy, the W doping could enhance the thermal transport of monolayer MoSe2 due to reduced three-phonon scattering phase space. For example, we observed that the 16.7% W doping increases the thermal conductivity of the monolayer MoSe2 with 2% Se vacancy by 80% if all vacancies can be suppressed by W-doping. However, the W doping in the defective MoSe2 amplifies the influence of the phonon scattering caused by the Se vacancies, which results in a further decrease in thermal conductivity of monolayer MoSe2 with defects. This is found to be related with higher phonon density of states of Mo0.83W0.17Se2 and larger mass difference between W and Se atoms compared to Mo and Se atoms. This study deciphers the effect of defects and doping on the thermal conductivity of monolayer MoSe2, which helps us understand the mechanism of defect-induced phonon transport, and provides insights into enhancing the heat dissipation in MoSe2-based electronic devices.

Production of Se-methylselenocysteine in transgenic plants expressing selenocysteine methyltransferase

PubMed Central

Ellis, Danielle R; Sors, Thomas G; Brunk, Dennis G; Albrecht, Carrie; Orser, Cindy; Lahner, Brett; Wood, Karl V; Harris, Hugh H; Pickering, Ingrid J; Salt, David E

2004-01-01

Background It has become increasingly evident that dietary Se plays a significant role in reducing the incidence of lung, colorectal and prostate cancer in humans. Different forms of Se vary in their chemopreventative efficacy, with Se-methylselenocysteine being one of the most potent. Interestingly, the Se accumulating plant Astragalus bisulcatus (Two-grooved poison vetch) contains up to 0.6% of its shoot dry weight as Se-methylselenocysteine. The ability of this Se accumulator to biosynthesize Se-methylselenocysteine provides a critical metabolic shunt that prevents selenocysteine and selenomethionine from entering the protein biosynthetic machinery. Such a metabolic shunt has been proposed to be vital for Se tolerance in A. bisulcatus. Utilization of this mechanism in other plants may provide a possible avenue for the genetic engineering of Se tolerance in plants ideally suited for the phytoremediation of Se contaminated land. Here, we describe the overexpression of a selenocysteine methyltransferase from A. bisulcatus to engineer Se-methylselenocysteine metabolism in the Se non-accumulator Arabidopsis thaliana (Thale cress). Results By over producing the A. bisulcatus enzyme selenocysteine methyltransferase in A. thaliana, we have introduced a novel biosynthetic ability that allows the non-accumulator to accumulate Se-methylselenocysteine and γ-glutamylmethylselenocysteine in shoots. The biosynthesis of Se-methylselenocysteine in A. thaliana also confers significantly increased selenite tolerance and foliar Se accumulation. Conclusion These results demonstrate the feasibility of developing transgenic plant-based production of Se-methylselenocysteine, as well as bioengineering selenite resistance in plants. Selenite resistance is the first step in engineering plants that are resistant to selenate, the predominant form of Se in the environment. PMID:15005814

Two-dimensional GaSe/MoSe2 misfit bilayer heterojunctions by van der Waals epitaxy.

PubMed

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; Huang, Bing; Puretzky, Alexander A; Ma, Cheng; Wang, Kai; Zhou, Wu; Pantelides, Sokrates T; Chi, Miaofang; Kravchenko, Ivan; Fowlkes, Jason; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

2016-04-01

Two-dimensional (2D) heterostructures hold the promise for future atomically thin electronics and optoelectronics because of their diverse functionalities. Although heterostructures consisting of different 2D materials with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) epitaxy, constructing heterostructures from layered semiconductors with large lattice misfits remains challenging. We report the growth of 2D GaSe/MoSe2 heterostructures with a large lattice misfit using two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientation between the two layers, forming a periodic superlattice. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe2 monolayer domains in lateral GaSe/MoSe2 heterostructures, GaSe monolayers are found to overgrow MoSe2 during CVD, forming a stripe of vertically stacked vdW heterostructures at the crystal interface. Such vertically stacked vdW GaSe/MoSe2 heterostructures are shown to form p-n junctions with effective transport and separation of photogenerated charge carriers between layers, resulting in a gate-tunable photovoltaic response. These GaSe/MoSe2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.

Two-dimensional GaSe/MoSe2 misfit bilayer heterojunctions by van der Waals epitaxy

PubMed Central

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; Huang, Bing; Puretzky, Alexander A.; Ma, Cheng; Wang, Kai; Zhou, Wu; Pantelides, Sokrates T.; Chi, Miaofang; Kravchenko, Ivan; Fowlkes, Jason; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

2016-01-01

Two-dimensional (2D) heterostructures hold the promise for future atomically thin electronics and optoelectronics because of their diverse functionalities. Although heterostructures consisting of different 2D materials with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) epitaxy, constructing heterostructures from layered semiconductors with large lattice misfits remains challenging. We report the growth of 2D GaSe/MoSe2 heterostructures with a large lattice misfit using two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientation between the two layers, forming a periodic superlattice. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe2 monolayer domains in lateral GaSe/MoSe2 heterostructures, GaSe monolayers are found to overgrow MoSe2 during CVD, forming a stripe of vertically stacked vdW heterostructures at the crystal interface. Such vertically stacked vdW GaSe/MoSe2 heterostructures are shown to form p-n junctions with effective transport and separation of photogenerated charge carriers between layers, resulting in a gate-tunable photovoltaic response. These GaSe/MoSe2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells. PMID:27152356

The response of broccoli (Brassica oleracea convar. italica) varieties on foliar application of selenium: uptake, translocation, and speciation.

PubMed

Šindelářová, Kristýna; Száková, Jiřina; Tremlová, Jana; Mestek, Oto; Praus, Lukáš; Kaňa, Antonín; Najmanová, Jana; Tlustoš, Pavel

2015-01-01

A model small-scale field experiment was set up to investigate selenium (Se) uptake by four different varieties of broccoli plants, as well as the effect of Se foliar application on the uptake of essential elements for plants calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), sulfur (S), and zinc (Zn). Foliar application of sodium selenate (Na2SeO4) was carried out at two rates (25 and 50 g Se/ha), and an untreated control variant was included. Analyses of individual parts of broccoli were performed, whereby it was found that Se in the plant accumulates mainly in the flower heads and slightly less in the leaves, stems, and roots, regardless of the Se rate and broccoli variety. In most cases, there was a statistically significant increase of Se content in all parts of the plant, while there was no confirmed systematic influence of the addition of Se on the changing intake of other monitored elements. Selenization of broccoli leads to an effective increase in the Se content at a rate of 25 g/ha, whereas the higher rate did not result in a substantial increase of Se content compared to the lower rate in all varieties. Therefore, the rate of 25 g/ha can be recommended as effective to produce broccoli with an increased Se content suitable for consumption. Moreover, Se application resulted in an adequate increase of the main organic compounds of Se, such as selenocystine (SeCys2), selenomethionine (SeMet), and Se-methylselenocysteine (Se-MeSeCys).

Selenium biofortification of broccoli and carrots grown in soil amended with Se-enriched hyperaccumulator Stanleya pinnata

USDA-ARS?s Scientific Manuscript database

Amending soils with Se-hyperaccumulator plant derived sources of selenium (Se) may be useful for increasing Se content in food crops in Se-deficient regions of the world. In this study, we evaluated total Se and the different chemical species of Se in broccoli and carrots grown in soils amended with...

Three-Dimensional Volumetric Assessment of Diastolic Function by Cardiac Magnetic Resonance Imaging: The Multi-Ethnic Study of Atherosclerosis (MESA).

PubMed

Nacif, Marcelo S; Almeida, Andre L C; Young, Alistair A; Cowan, Brett R; Armstrong, Anderson C; Yang, Eunice; Sibley, Christopher T; Hundley, W Gregory; Liu, Songtao; Lima, Joao Ac; Bluemke, David A

2017-01-01

Cardiac Magnetic Resonance is in need of a simple and robust method for diastolic function assessment that can be done with routine protocol sequences. To develop and validate a three-dimensional (3D) model-based volumetric assessment of diastolic function using cardiac magnetic resonance (CMR) imaging and compare the results obtained with the model with those obtained by echocardiography. The study participants provided written informed consent and were included if having undergone both echocardiography and cine steady-state free precession (SSFP) CMR on the same day. Guide points at the septal and lateral mitral annulus were used to define the early longitudinal relaxation rate (E'), while a time-volume curve from the 3D model was used to assess diastolic filling parameters. We determined the correlation between 3D CMR and echocardiography and the accuracy of CMR in classifying the diastolic function grade. The study included 102 subjects. The E/A ratio by CMR was positively associated with the E/A ratio by echocardiography (r = 0.71, p < 0.0001). The early diastolic relaxation velocity by tissue Doppler and longitudinal relaxation rate for the lateral mitral annulus displacement were positively associated (p = 0.007), as were the ratio between Doppler E/e' and CMR E/E' (p = 0.01). CMR-determined normalized peak E (NE) and deceleration time (DT) were able to predict diastolic dysfunction (areas under the curve [AUCs] = 0.70 and 0.72, respectively). In addition, the lateral E/E' ratio showed good utility in identifying diastolic dysfunction (AUC = 0.80). Overall, echocardiography and CMR interobserver and intraobserver agreements were excellent (intraclass correlation coefficient range 0.72 - 0.97). 3D modeling of standard cine CMR images was able to identify study subjects with reduced diastolic function and showed good reproducibility, suggesting a potential for a routine diastolic function assessment by CMR. A ressonância magnética cardíaca necessita de um método simples e robusto para a avaliação da função diastólica que pode ser feito com sequências protocolares de rotina. Desenvolver e validar a avaliação volumétrica da função diastólica através de um modelo tridimensional (3D) com utilização de imagens de ressonância magnética cardíaca (RMC) e comparar os resultados obtidos com este modelo com os obtidos por ecocardiografia. Os participantes do estudo assinaram um termo de consentimento e foram incluídos se tivessem sido submetidos no mesmo dia tanto à ecocardiografia quanto à cine RMC com precessão livre no estado estacionário (steady-state free precession, SSFP). Pontos-guia foram utilizados no anel mitral septal e lateral para definir a velocidade de estiramento no início da diástole (E'), enquanto curvas de volume-tempo do modelo 3D foram utilizadas para avaliar os parâmetros de enchimento diastólico. Foram determinadas a correlação entre a RMC 3D e a ecocardiografia, além da acurácia da RMC em classificar o grau de função diastólica. Ao todo, 102 sujeitos foram incluídos no estudo. A razão E/A pela RMC esteve positivamente associada com a razão E/A obtida pela ecocardiografia (r = 0,71, p < 0,0001). Estiveram positivamente associadas a velocidade de relaxamento diastólico inicial ao Doppler tecidual e a velocidade de relaxamento longitudinal de deslocamento do anel mitral lateral (p = 0,007), bem como a razão entre E/e' por Doppler e E/E' pela RMC (p = 0,01). A velocidade normalizada de pico de enchimento (EM) determinada pela RMC e o tempo de desaceleração (TD) foram capazes de predizer a disfunção diastólica (áreas sob a curva [AUCs] = 0,70 e 0,72, respectivamente). Além disso, a razão E/E' lateral mostrou boa utilidade para a identificação da disfunção diastólica (AUC = 0,80). No geral, a ecocardiografia e a RMC apresentaram excelente concordância interobservador e intraobservador (coeficiente de correlação intraclasse 0,72 - 0,97). Uma modelagem 3D de imagens padrões de cine RMC foi capaz de identificar os indivíduos do estudo com função diastólica reduzida e mostrou uma boa reprodutibilidade, sugerindo ter potencial na avaliação rotineira da função diastólica por RMC.

Effects of selenite and selenate application on distribution and transformation of selenium fractions in soil and its bioavailability for wheat (Triticum aestivum L.).

PubMed

Ali, Fayaz; Peng, Qin; Wang, Dan; Cui, Zewei; Huang, Jie; Fu, Dongdong; Liang, Dongli

2017-03-01

This study investigated the effect of selenate and selenite application on the distribution, transformation of selenium (Se) fractions in soil, as well as the accumulation and availability of Se in each part of wheat plants. A pot experiment was conducted using different concentrations of exogenous selenite or selenate (0.5, 1, 2.5, 5, and 10 mg Se kg -1 soil). Sequential extraction was used to determine the Se fractions in soil, and different models were used to study the behavior of Se in soil and its availability to wheat. Results showed that the distribution and availability of Se in soil and its accumulation in wheat affected both by Se concentrations and forms of exogenous Se. In selenite-treated soil, the proportion of exchangeable and carbonate-bound Se (EXC-Se) (21-42%) fraction increased compared to that in control (12%), while organic matter-bound Se (OM-Se) (23-33%) and Fe-Mn oxide-bound Se (FMO-Se) (11-15%) fractions decreased compare with those in control (37 and 32%, respectively). In selenate-treated soil, soluble-Se (SOL-Se) fraction (30-54%) increased and the OM-Se (9.8-20%) and FMO-Se (4.7-14.2%) fractions decreased compared with those in control. Residual Se (RES-Se) fraction was increased for selenite (7.4-13.4%) and selenate (12-20%) treatments compared with that in control (6.5%). In comparison with control, the available Se (SOL-Se + EXC-Se) fraction increased for both selenite (32-47%) or selenate (54-72%) treatments. Moreover, at the same rate of Se application, Se availability was higher in wheat grown in selenate-treated soils than that in selenite-treated soils. The redistribution index (U ts ) of Se increased from 1 (in control) to 1.2-1.9 and 1.5-2 for selenite and selenate treatments, respectively; additionally, the mobility factor (MF) in selenate-treated soil was 40-90% higher than that in selenite-treated soil. Furthermore, relative bonding intensity (I R ) for both selenite (0.38-0.45) and selenate treatment (0.33-0.41) decreased compared with that in control (0.55). These differences indicated that selenite and selenate varied in terms of fixation capacities in soil, in transformation and distribution of Se in soil fractions, and in their availability to plants. The results of Michaelis-Menten equation demonstrated the high affinity of leaf to selenate, and the high affinity of roots and grains to selenite. Selenate was dominant in nearly all parts of wheat plants and in each application level. However, the affinity of selenite to wheat grains suggests that selenite is a useful Se fertilizer that must be considered in biofortification programs. In-depth studies at the pot and field scales by using different wheat varieties and application methods of Se in different ecological zones must be conducted to elucidate the mechanism and biochemical properties of Se in soil-plant system and ultimately produce Se-rich staple foods.

Exploring the Behavior and Metabolic Transformations of SeNPs in Exposed Lactic Acid Bacteria. Effect of Nanoparticles Coating Agent

PubMed Central

Palomo-Siguero, Maria; Madrid, Yolanda

2017-01-01

The behavior and transformation of selenium nanoparticles (SeNPs) in living systems such as microorganisms is largely unknown. To address this knowledge gap, we examined the effect of three types of SeNP suspensions toward Lactobacillus delbrueckii subsp. bulgaricus LB-12 using a variety of techniques. SeNPs were synthesized using three types of coating agents (chitosan (CS-SeNPs), hydroxyethyl cellulose (HEC-SeNPs) and a non-ionic surfactant, surfynol (ethoxylated-SeNPs)). Morphologies of SeNPs were all spherical. Transmission electron microscopy (TEM) was used to locate SeNPs in the bacteria. High performance liquid chromatography (HPLC) on line coupled to inductively coupled plasma mass spectrometry (ICP-MS) was applied to evaluate SeNP transformation by bacteria. Finally, flow cytometry employing the live/dead test and optical density measurements at 600 nm (OD600) were used for evaluating the percentages of bacteria viability when supplementing with SeNPs. Negligible damage was detected by flow cytometry when bacteria were exposed to HEC-SeNPs or CS-SeNPs at a level of 10 μg Se mL−1. In contrast, ethoxylated-SeNPs were found to be the most harmful nanoparticles toward bacteria. CS-SeNPs passed through the membrane without causing damage. Once inside, SeNPs were metabolically transformed to organic selenium compounds. Results evidenced the importance of capping agents when establishing the true behavior of NPs. PMID:28783048

Structure and properties of ZnSxSe1-x thin films deposited by thermal evaporation of ZnS and ZnSe powder mixtures

NASA Astrophysics Data System (ADS)

Valeev, R. G.; Romanov, E. A.; Vorobiev, V. L.; Mukhgalin, V. V.; Kriventsov, V. V.; Chukavin, A. I.; Robouch, B. V.

2015-02-01

Interest to ZnSxSe1-x alloys is due to their band-gap tunability varying S and Se content. Films of ZnSxSe1-x were grown evaporating ZnS and ZnSe powder mixtures onto SiO2, NaCl, Si and ITO substrates using an original low-cost method. X-ray diffraction patterns and Raman spectroscopy, show that the lattice structure of these films is cubic ZnSe-like, as S atoms replace Se and film compositions have their initial S/Se ratio. Optical absorption spectra show that band gap values increase from 2.25 to 3 eV as x increases, in agreement with the literature. Because S atomic radii are smaller than Se, EXAFS spectra confirm that bond distances and Se coordination numbers decrease as the Se content decreases. The strong deviation from linearity of ZnSe coordination numbers in the ZnSxSe1-x indicate that within this ordered crystal structure strong site occupation preferences occur in the distribution of Se and S ions. The behavior is quantitatively confirmed by the strong deviation from the random Bernoulli distribution of the three sight occupation preference coefficients of the strained tetrahedron model. Actually, the ternary ZnSxSe1-x system is a bi-binary (ZnS+ZnSe) alloy with evanescent formation of ternary configurations throughout the x-range.

Selenium Distribution and Speciation in the Hyperaccumulator Astragalus bisulcatus and Associated Ecological Partners1[W][OA

PubMed Central

Valdez Barillas, José R.; Quinn, Colin F.; Freeman, John L.; Lindblom, Stormy D.; Fakra, Sirine C.; Marcus, Matthew A.; Gilligan, Todd M.; Alford, Élan R.; Wangeline, Ami L.; Pilon-Smits, Elizabeth A.H.

2012-01-01

The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may affect ecological interactions and whether associated partners may affect Se hyperaccumulation. The Se hyperaccumulator Astragalus bisulcatus was collected in its natural seleniferous habitat, and x-ray fluorescence mapping and x-ray absorption near-edge structure spectroscopy were used to characterize Se distribution and speciation in all organs as well as in encountered microbial symbionts and herbivores. Se was present at high levels (704–4,661 mg kg−1 dry weight) in all organs, mainly as organic C-Se-C compounds (i.e. Se bonded to two carbon atoms, e.g. methylselenocysteine). In nodule, root, and stem, up to 34% of Se was found as elemental Se, which was potentially due to microbial activity. In addition to a nitrogen-fixing symbiont, the plants harbored an endophytic fungus that produced elemental Se. Furthermore, two Se-resistant herbivorous moths were discovered on A. bisulcatus, one of which was parasitized by a wasp. Adult moths, larvae, and wasps all accumulated predominantly C-Se-C compounds. In conclusion, hyperaccumulators live in association with a variety of Se-resistant ecological partners. Among these partners, microbial endosymbionts may affect Se speciation in hyperaccumulators. Hyperaccumulators have been shown earlier to negatively affect Se-sensitive ecological partners while apparently offering a niche for Se-resistant partners. Through their positive and negative effects on different ecological partners, hyperaccumulators may influence species composition and Se cycling in seleniferous ecosystems. PMID:22645068

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matetskiy, A. V., E-mail: mateckij@iacp.dvo.ru; Kibirev, I. A.; Saranin, A. A.

The formation, structure and electronic properties of SnSe{sub 2}–Bi{sub 2}Se{sub 3} van der Waals heterostructures were studied. Both heterostructures, SnSe{sub 2} on Bi{sub 2}Se{sub 3} and Bi{sub 2}Se{sub 3} on SnSe{sub 2}, were grown epitaxially with high crystallinity and sharp interfaces. Their electron band structures are of trivial and topological insulators, respectively. The Dirac surface states of Bi{sub 2}Se{sub 3} survive under the SnSe{sub 2} overlayer. One triple layer of SnSe{sub 2} was found to be an efficient spacer for separating a Bi{sub 2}Se{sub 3} topological-insulator slab into two and creating the corresponding topological surface states.

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE PAGES

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.; ...

2016-08-22

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

The fascinating facets of plant selenium accumulation - biochemistry, physiology, evolution and ecology.

PubMed

Schiavon, Michela; Pilon-Smits, Elizabeth A H

2017-03-01

Contents 1582 I. 1582 II. 1583 III. 1588 IV. 1590 V. 1592 1592 References 1592 SUMMARY: The importance of selenium (Se) for medicine, industry and the environment is increasingly apparent. Se is essential for many species, including humans, but toxic at elevated concentrations. Plant Se accumulation and volatilization may be applied in crop biofortification and phytoremediation. Topics covered here include beneficial and toxic effects of Se on plants, mechanisms of Se accumulation and tolerance in plants and algae, Se hyperaccumulation, and ecological and evolutionary aspects of these processes. Plant species differ in the concentration and forms of Se accumulated, Se partitioning at the whole-plant and tissue levels, and the capacity to distinguish Se from sulfur. Mechanisms of Se hyperaccumulation and its adaptive significance appear to involve constitutive up-regulation of sulfate/selenate uptake and assimilation, associated with elevated concentrations of defense-related hormones. Hyperaccumulation has evolved independently in at least three plant families, probably as an elemental defense mechanism and perhaps mediating elemental allelopathy. Elevated plant Se protects plants from generalist herbivores and pathogens, but also gives rise to the evolution of Se-resistant specialists. Plant Se accumulation affects ecological interactions with herbivores, pollinators, neighboring plants, and microbes. Hyperaccumulation tends to negatively affect Se-sensitive ecological partners while facilitating Se-resistant partners, potentially affecting species composition and Se cycling in seleniferous ecosystems. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Comparative effects of selenite and selenate on nitrate assimilation in barley seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Harbit, K. B.; Huffaker, R. C.

1990-01-01

The effect of SeO3= and SeO4= on NO3- assimilation in 8-d-old barley (Hordeum vulgare L.) seedlings was studied over a 24-h period. Selenite at 0.1 mol m-3 in the uptake solutions severely inhibited the induction of NO3- uptake and active nitrate reductases. Selenate, at 1.0 mol m-3 in the nutrient solution, had little effect on induction of activities of these systems until after 12 h; however, when the seedlings were pretreated with 1.0 mol m-3 SeO4= for 24 h, subsequent NO3- uptake from SeO4(=) -free solutions was inhibited about 60%. Sulphate partially alleviated the inhibitory effect of SeO3= when supplied together in the ambient solutions, but had no effect in seedlings pretreated with SeO3=. By contrast, SO4= partially alleviated the inhibitory effect of SeO4= even in seedlings pretreated with SeO4=. Since uptake of NO3- by intact seedlings was also inhibited by SO3=, the percentage of the absorbed NO3- that was reduced was not affected. By contrast, SeO4=, which affected NO3- uptake much less, inhibited the percentage reduced of that absorbed. However, when supplied to detached leaves, both SeO3= and SeO4= inhibited the in vivo reduction of NO3- as well as induction of nitrate reductase and nitrite reductase activities. Selenite was more inhibitory than SeO4= ; approximately a five to 10 times higher concentration of SeO4= than SeO3= was required to achieve similar inhibition. In detached leaves, the inhibitory effect of both SeO3= and SeO4= on in vivo NO3- reduction as well as on the induction of nitrate reductase activity was partially alleviated by SO4=. The inhibitory effects of Se salts on the induction of the nitrite reductase were, however, completely alleviated by SO4=. The results show that in barley seedlings SeO3= is more toxic than SeO4=. The reduction of SeO4= to SeO3= may be a rate limiting step in causing Se toxicity.

Implicit and explicit self-esteem discrepancies in people with psychogenic nonepileptic seizures.

PubMed

Dimaro, Lian V; Roberts, Nicole A; Moghaddam, Nima G; Dawson, David L; Brown, Ian; Reuber, Markus

2015-05-01

Self-esteem (SE), or one's sense of competence and worth, is reduced in many mental and physical disorders. Low SE is associated with perceived stigma and disability and poor treatment outcomes. The present study examined implicit and explicit SE (automatic and deliberate views about the self) in people with epilepsy and people with psychogenic nonepileptic seizures (PNESs). Discrepancies between implicit SE and explicit SE have been found to correlate with psychological distress in disorders often associated with PNESs but are relatively unexplored in PNESs. We hypothesized that, compared with epilepsy, PNESs would be associated with lower self-reported SE and greater discrepancies between implicit SE and explicit SE. Thirty adults with PNESs, 25 adults with epilepsy, and 31 controls without a history of seizures were asked to complete the Rosenberg Self-esteem Scale as a measure of explicit SE and an Implicit Relational Assessment Procedure as a measure of implicit SE. The State-Trait Anxiety Inventory and Patient Health Questionnaire-15 (a somatic symptom inventory) were also administered. We found significant group differences in explicit (p<0.001) but not implicit SE. Patients with PNESs reported lower SE than the other groups. No group differences were found in implicit SE. Implicit-explicit SE discrepancies were larger in the group with PNESs than in the other groups (p<0.001). Higher frequency of PNESs (but not epileptic seizures) was associated with lower explicit SE (rs=-.83, p<0.01) and greater SE discrepancies (i.e., lower explicit relative to implicit SE; rs=.65, p<0.01). These relationships remained significant when controlling for anxiety and somatization. Patients with PNESs had lower explicit SE than those with epilepsy or healthy controls. In keeping with our expectations, there were greater discrepancies between implicit SE and explicit SE among patients with PNESs than in the other groups. Our results, including the strong relationship between PNES frequency, anxiety, and explicit-implicit SE discrepancies, support the interpretation that PNESs serve to reduce cognitive dissonance, perhaps protecting patients' implicit SE. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

The effect of dietary bacterial organic selenium on growth performance, antioxidant capacity, and Selenoproteins gene expression in broiler chickens.

PubMed

Dalia, A M; Loh, T C; Sazili, A Q; Jahromi, M F; Samsudin, A A

2017-08-18

Selenium (Se) is an essential trace mineral in broilers, which has several important roles in biological processes. Organic forms of Se are more efficient than inorganic forms and can be produced biologically via Se microbial reduction. Hence, the possibility of using Se-enriched bacteria as feed supplement may provide an interesting source of organic Se, and benefit broiler antioxidant system and other biological processes. The objective of this study was to examine the impacts of inorganic Se and different bacterial organic Se sources on the performance, serum and tissues Se status, antioxidant capacity, and liver mRNA expression of selenoproteins in broilers. Results indicated that different Se sources did not significantly (P ≤ 0.05) affect broiler growth performance. However, bacterial organic Se of T5 (basal diet +0.3 mg /kg feed ADS18 Se), T4 (basal diet +0.3 mg /kg feed ADS2 Se), and T3 (basal diet +0.3 mg /kg feed ADS1 Se) exhibited significantly (P ≤ 0.05) highest Se concentration in serum, liver, and kidney respectively. Dietary inorganic Se and bacterial organic Se were observed to significantly affect broiler serum ALT, AST, LDH activities and serum creatinine level. ADS18 supplemented Se of (Stenotrophomonas maltophilia) bacterial strain showed the highest GSH-Px activity with the lowest MDA content in serum, and the highest GSH-Px and catalase activity in the kidney, while bacterial Se of ADS2 (Klebsiella pneumoniae) resulted in a higher level of GSH-Px1 and catalase in liver. Moreover, our study showed that in comparison with sodium selenite, only ADS18 bacterial Se showed a significantly higher mRNA level in GSH-Px1, GSH-Px4, DIO1, and TXNDR1, while both ADS18 and ADS2 showed high level of mRNA of DIO2 compared to sodium selenite. The supplementation of bacterial organic Se in broiler chicken, improved tissue Se deposition, antioxidant status, and selenoproteins gene expression, and can be considered as an effective alternative source of Se in broiler chickens.

Temporal variations in dissolved selenium in Lake Kinneret (Israel)

USGS Publications Warehouse

Nishri, A.; Brenner, I.B.; Hall, G.E.M.; Taylor, Howard E.

1999-01-01

Selenium is an essential micronutrient for the growth of the dinoflagellate Peridinium gatunense that dominates the spring algal bloom in Lake Kinneret (LK). The relationship between the levels of dissolved selenium species and the occurance of algal blooms in this lake was studied. During algal blooms of P. gatunense in spring and of the blue-green Aphanizomenon ovalisporum in fall (in 1994) the concentration of epilimnetic dissolved organic Se (Se(org)) increased whereas that of selenite (SeIV) decreased, to levels below the limit of detection: 5 ng/l. The disappearance of SeIV during these blooms is attributed to algal uptake and it is suggested that the growth of both algae may have depended on Se(org) regeneration. A budget performed for selenate (SeVI) suggests that this species is also consumed by algae but to a lesser extent than SeIV (in 1994 ~40% of the epilimnetic load). During the stratification period the hypolimnion of Lake Kinneret becomes anoxic, with high levels of dissolved sulfide. The affects of this environment on the distribution of Se oxy-anions, selenite (SeIV) and selenate(SeVI), were also studied. At the onset of thermal stratification (March) about 35% of the lake inventory of both Se oxidized species are entrapped in the hypolimnion. During stages of oxygen depletion and H2S accumulation, SeIV is completely and SeVI partially removed from this layer. The removal is attributed to reduction followed by formation of particulate reduced products, such as elemental selenium Se(o). The ratio between SeVI to total dissolved selenium (SE(T)) in water sources to the lake is ~0.84, about twice the corresponding ratio in the lake (~0.44, during holomixis). In the lake about 75% of annual SeVI inflow from external sources undergoes reduction to selenide (Se-II) and Se(o) through epilimnetic algal assimilation and hypolimnetic anoxic reduction, respectively. It is suggested that the latter oxidation of the dissolved organic selenide released from biogenic particles and of Se(o) only to the tetravalent species is the cause for the lower ratio of SeVI/Se(T) in the lake.

Selenium bioaccumulation and hazards in a fish community affected by coal fly ash effluent

USGS Publications Warehouse

Besser, John M.; Giesy, John P.; Brown, Russell W.; Buell, Julie M.; Dawson, G. A.

1996-01-01

Bioaccumulation of selenium (Se) in the fish community of Pigeon River/Pigeon Lake, which receives inputs of Se from a coal fly ash disposal facility, was studied to assess potential hazards of Se to fish, wildlife, and humans. Se concentrations in fish from sites receiving seepage and effluents from fly ash disposal ponds were significantly greater than those in fish from upstream, where Se concentrations were near background concentrations. Se concentrations differed among fish species, and interspecific variation was greatest at the most contaminated locations. Differences in Se bioaccumulation among fish species were not consistently associated with differences in trophic status. Although Se concentrations in northern pike were consistently less than those in likely prey species, large yellow perch contained Se concentrations as great as those in spottail shiners, their likely prey. Se bioaccumulation may have been influenced by differences in habitat preferences, as limnetic species generally contained greater Se concentrations than benthic species. Se concentrations in fish from the lower Pigeon River and Pigeon Lake did not exceed lowest observable adverse effect concentrations (LOAECs) for Se in tissues of fish species, but exceeded LOAECs for dietary Se exposure of sensitive species of birds and mammals. Human consumption of moderate quantities of fish from the areas studied should not result in excessive Se intake.

Thermodynamic consideration and ground-state search of icosahedral boron subselenide B12(B1-xSex) 2 from a first-principles cluster expansion

NASA Astrophysics Data System (ADS)

Ektarawong, A.

2018-05-01

The phase stability of icosahedral boron subselenide B12(B1-xSex) 2 , where 0.5 ≤x ≤1 , is explored using a first-principles cluster expansion. The results shows that, instead of a continuous solid solution, B12(B1-xSex) 2 is thermodynamically stable as an individual line compound at the composition of B9.5Se . The ground-state configuration of B9.5Se is represented by a mixture of B12(Se-Se), B12(B-Se), and B12(Se-B) with a ratio of 1:1:1, where they form a periodic A B C A B C ⋯ stacking sequence of B12(Se-Se), B12(B-Se), and B12(Se-B) layers along the c axis of the hexagonal conventional unit cell. The structural and electronic properties of the ground-state B9.5Se are also derived and discussed. By comparing the derived ground-state properties of B9.5Se to the existing experimental data of boron subselenide B˜13Se , I proposed that the as-synthesized boron subselenide B˜13Se , as reported in the literature, has the actual composition of B9.5Se .

Superior Na-ion storage properties of high aspect ratio SnSe nanoplates prepared by a spray pyrolysis process

NASA Astrophysics Data System (ADS)

Park, Gi Dae; Lee, Jong-Heun; Kang, Yun Chan

2016-06-01

SnSe nanoplates with thin and uniform morphology are prepared by one-pot spray pyrolysis, and are examined as anode materials for Na-ion batteries. During the spray pyrolysis process, metallic Se and Sn are prepared from SeO2 and SnO2, respectively, under a reducing atmosphere. Metallic Sn and metalloid Se, with melting points of 232 and 221 °C, respectively, form a melted Sn-Se mixture, which reacts exothermally to form SnSe nanocrystals. Several of these nanocrystals are grown simultaneously forming a micron-sized powder. Complete elimination of the excess amount of metalloid Se, by forming H2Se gas, results in aggregation-free SnSe nanoplates. The aspect ratio of these nanoplates is as high as 11.3. The discharge capacities for the SnSe nanoplates, prepared from spray solutions containing 100, 400, and 800% of the stoichiometric SeO2 content needed to form SnSe, are 407, 558, and 211 mA h g-1, respectively, after 50 cycles at a constant current density of 0.3 A g-1 their capacity retentions calculated from the second cycle onwards are 77, 100, and 60%, respectively. The phase pure SnSe nanoplates with a high aspect ratio show good cycling and rate performances for Na-ion storage.SnSe nanoplates with thin and uniform morphology are prepared by one-pot spray pyrolysis, and are examined as anode materials for Na-ion batteries. During the spray pyrolysis process, metallic Se and Sn are prepared from SeO2 and SnO2, respectively, under a reducing atmosphere. Metallic Sn and metalloid Se, with melting points of 232 and 221 °C, respectively, form a melted Sn-Se mixture, which reacts exothermally to form SnSe nanocrystals. Several of these nanocrystals are grown simultaneously forming a micron-sized powder. Complete elimination of the excess amount of metalloid Se, by forming H2Se gas, results in aggregation-free SnSe nanoplates. The aspect ratio of these nanoplates is as high as 11.3. The discharge capacities for the SnSe nanoplates, prepared from spray solutions containing 100, 400, and 800% of the stoichiometric SeO2 content needed to form SnSe, are 407, 558, and 211 mA h g-1, respectively, after 50 cycles at a constant current density of 0.3 A g-1 their capacity retentions calculated from the second cycle onwards are 77, 100, and 60%, respectively. The phase pure SnSe nanoplates with a high aspect ratio show good cycling and rate performances for Na-ion storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02983c

The Impact of Phosphorus Supply on Selenium Uptake During Hydroponics Experiment of Winter Wheat (Triticum aestivum) in China.

PubMed

Liu, Hongen; Shi, Zhiwei; Li, Jinfeng; Zhao, Peng; Qin, Shiyu; Nie, Zhaojun

2018-01-01

Selenium (Se) is a necessary trace element for humans and animals, and Se fertilization is an efficient way to increase Se concentration in the edible parts of crops, thus enhance the beneficiary effects of Se in human and animal health. Due to the similarity of physical and chemical properties between phosphate () and selenite (), phosphorus (P) supply often significantly impacts the absorption of Se in plants, but little is known about how P supply influences the subcellular distribution and chemical forms of Se. In this study, the effects of P supply on subcellular distribution and chemical forms of Se in winter wheat were investigated in a hydroponic trial with medium Se level (0.1 mg Se L -1 ). P was applied with three concentrations (0.31, 3.1, and 31 mg P L -1 ) in the experiment. The results showed that increasing P supply significantly decreased the concentration and accumulation of Se in the roots, stems, and leaves of winter wheat. An increase in P supply significantly inhibited Se accumulation in the root cell wall, but enhanced Se distribution in the organelles and soluble fraction of root cells. These findings suggest that increased P supply inhibited the root-to-shoot transport of Se. An increase in P supply enhanced Se accumulation in the cell wall of plant stems (both apical and axillary stem) and cell organelles of plants leaves, but inhibited Se distribution in the soluble fraction of stems and leaves. This suggests that P supply enhances Se transportation across the cell membrane in shoots of winter wheat. In addition, increased P supply also altered the chemical forms of Se in tissues of winter wheat. These findings will help in understanding of the regulation grain Se accumulation and provide a practical way to enhance Se intake for humans inform Se-enriched grains.

Selenium in Cattle: A Review.

PubMed

Mehdi, Youcef; Dufrasne, Isabelle

2016-04-23

This review article examines the role of selenium (Se) and the effects of Se supplementation especially in the bovine species. Selenium is an important trace element in cattle. Some of its roles include the participation in the antioxidant defense the cattle farms. The nutritional requirements of Se in cattle are estimated at 100 μg/kg DM (dry matter) for beef cattle and at 300 μg/kg DM for dairy cows. The rations high in fermentable carbohydrates, nitrates, sulfates, calcium or hydrogen cyanide negatively influence the organism's use of the selenium contained in the diet. The Se supplementation may reduce the incidence of metritis and ovarian cysts during the postpartum period. The increase in fertility when adding Se is attributed to the reduction of the embryonic death during the first month of gestation. A use of organic Se in feed would provide a better transfer of Se in calves relative to mineral Se supplementation. The addition of Se yeasts in the foodstuffs of cows significantly increases the Se content and the percentage of polyunsaturated fatty acids (PUFA) in milk compared to the addition of sodium selenite. The enzyme 5-iodothyronine deiodinase is a seleno-dependent selenoprotein. It is one of the last proteins to be affected in the event of Se deficiency. This delay in response could explain the fact that several studies did not show the effect of Se supplementation on growth and weight gain of calves. Enrichment of Se in the diet did not significantly affect the slaughter weight and carcass yield of bulls. The impact and results of Se supplementation in cattle depend on physiological stage, Se status of animals, type and content of Se and types of Se administration. Further studies in Se supplementation should investigate the speciation of Se in food and yeasts, as well as understanding their metabolism and absorption. This constitute a path to exploit in order to explain certain different effects of Se.

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods1[OA

PubMed Central

Bañuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.; Marcus, Matthew A.; Yang, Soo In; Pickering, Ingrid J.; Pilon-Smits, Elizabeth A.H.; Freeman, John L.

2011-01-01

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping (μXRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). μXRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tips contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a “free” nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. μXRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers. PMID:21059825

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping ({micro}XRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). {micro}XRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tipsmore » contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a 'free' nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. {micro}XRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers.« less

Kinetics and equilibrium adsorption study of selenium oxyanions onto Al/Si and Fe/Si coprecipitates.

PubMed

Chan, Y T; Liu, Y T; Tzou, Y M; Kuan, W H; Chang, R R; Wang, M K

2018-05-01

Inappropriate treatments for the effluents from semiconductor plants might cause the releases and wide distributions of selenium (Se) into the ecosystems. In this study, Al/Si and Fe/Si coprecipitates were selected as model adsorbents as they often formed during the wastewater coagulation process, and the removal efficiency of selenite (SeO 3 ) and selenate (SeO 4 ) onto the coprecipitates were systematically examined. The removal efficiency of SeO 3 and SeO 4 was highly related to surface properties of Al/Si and Fe/Si coprecipitates. The surface-attached Al shell of Al/Si coprecipitates shielded a portion of negative charges from the core SiO 2 , resulting in a higher point of zero charge than that of Fe/Si coprecipitates. Thus, adsorption of SeO 3 /SeO 4 was favorable on the Al/Si coprecipitates. Adsorptions of both SeO 3 and SeO 4 on Al/Si coprecipitates were exothermic reactions. On Fe/Si coprecipitates, while SeO 3 adsorption also showed the exothermic behavior, SeO 4 adsorption occurred as an endothermic reaction. The kinetic adsorption data of SeO 3 /SeO 4 on Al/Si and Fe/Si coprecipitates were described well by the pseudo-second-order kinetic model. SeO 4 and SeO 3 adsorption on Fe/Si or Al/Si were greatly inhibited by the strong PO 4 ligand, whereas the weak ligand such as SO 4 only significantly affected SeO 4 adsorption. The weakest complex between SeO 4 and Al was implied by the essentially SeO 4 desorption as SeO 4 /PO 4 molar ratios decreased from 0.5 to 0.2. These results were further confirmed by the less SeO 4 desorption (41%) from Fe/Si coprecipitates than that from Al/Si coprecipitates (78%) while PO 4 was added sequentially. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced Sb 2Se 3 solar cell performance through theory-guided defect control: Enhanced Sb 2Se 3 solar cell performance

DOE PAGES

Liu, Xinsheng; Xiao, Xun; Yang, Ye; ...

2017-05-30

Defects present in the absorber layer largely dictate photovoltaic device performance. Recently, a binary photovoltaic material, Sb 2Se 3, has drawn much attention due to its low-cost and nontoxic constituents and rapid performance promotion. So far, however, the intrinsic defects of Sb 2Se 3 remain elusive. Here in this work, through a combined theoretical and experimental investigation, we revealed that shallow acceptors, SeSb antisites, are the dominant defects in Sb 2Se 3 produced in an Se-rich environment, where deep donors, SbSe and VSe, dominate in Sb 2Se 3 produced in an Se-poor environment. We further constructed a superstrate CdS/Sb 2Semore » 3 thin-film solar cell achieving 5.76% efficiency through in situ Se compensation during Sb 2Se 3 evaporation and through careful optimization of absorber layer thickness. In conclusion, the understanding of intrinsic defects in Sb 2Se 3 film and the demonstrated success of in situ Se compensation strategy pave the way for further efficiency improvement of this very promising photovoltaic technology.« less

Elemental selenium at nano size (Nano-Se) as a potential chemopreventive agent with reduced risk of selenium toxicity: comparison with se-methylselenocysteine in mice.

PubMed

Zhang, Jinsong; Wang, Xufang; Xu, Tongwen

2008-01-01

Selenium (Se) is an essential trace element with a narrow margin between beneficial and toxic effects. As a promising chemopreventive agent, its use requires consumption over the long term, so the toxicity of Se is always a crucial concern. Based on clinical findings and recent studies in selenoprotein gene-modified mice, it is likely that the antioxidant function of one or more selenoproteins is responsible for the chemopreventive effect of Se. Furthermore, upregulation of phase 2 enzymes by Se has been implicated as a possible chemopreventive mechanism at supranutritional dietary levels. Se-methylselenocysteine (SeMSC), a naturally occurring organic Se product, is considered as one of the most effective chemopreventive selenocompounds. The present study revealed that, as compared with SeMSC, elemental Se at nano size (Nano-Se) possessed equal efficacy in increasing the activities of glutathione peroxidase, thioredoxin reductase, and glutathione S-transferase, but had much lower toxicity as indicated by median lethal dose, acute liver injury, survival rate, and short-term toxicity. Our results suggest that Nano-Se can serve as a potential chemopreventive agent with reduced risk of Se toxicity.

Do selenium hyperaccumulators affect selenium speciation in neighboring plants and soil? An X-Ray Microprobe Analysis.

PubMed

El Mehdawi, Ali F; Lindblom, Stormy D; Cappa, Jennifer J; Fakra, Sirine C; Pilon-Smits, Elizabeth A H

2015-01-01

Neighbors of Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus were found earlier to have elevated Se levels. Here we investigate whether Se hyperaccumulators affect Se localization and speciation in surrounding soil and neighboring plants. X-ray fluorescence mapping and X-ray absorption near-edge structure spectroscopy were used to analyze Se localization and speciation in leaves of Artemisia ludoviciana, Symphyotrichum ericoides and Chenopodium album growing next to Se hyperaccumulators or non-accumulators at a seleniferous site. Regardless of neighbors, A. ludoviciana, S. ericoides and C. album accumulated predominantly (73-92%) reduced selenocompounds with XANES spectra similar to the C-Se-C compounds selenomethionine and methyl-selenocysteine. Preliminary data indicate that the largest Se fraction (65-75%), both in soil next to hyperaccumulator S. pinnata and next to nonaccumulator species was reduced Se with spectra similar to C-Se-C standards. These same C-Se-C forms are found in hyperaccumulators. Thus, hyperaccumulator litter may be a source of organic soil Se, but soil microorganisms may also contribute. These findings are relevant for phytoremediation and biofortification since organic Se is more readily accumulated by plants, and more effective for dietary Se supplementation.

Stable isotope fractionation of selenium by natural microbial consortia

USGS Publications Warehouse

Ellis, A.S.; Johnson, T.M.; Herbel, M.J.; Bullen, T.D.

2003-01-01

The mobility and bioavailability of Se depend on its redox state, and reduction of Se oxyanions to less mobile, reduced species controls transport of this potentially toxic element in the environment. Stable isotope fractionation of Se is currently being developed as an indicator of Se immobilization through reduction. In this study, Se isotope fractionation resulting from reduction of Se(VI) and Se(IV) oxyanions by natural microbial consortia was measured in sediment slurry experiments under nearly natural conditions, with no substrate added. Experiments were conducted with a wide range of initial Se concentrations and with sediment and water from three locations with contrasting environmental settings. The products of Se(VI) and Se(IV) reduction were enriched in the lighter isotopes relative to the reactants. Shifts of -2.60/00 to -3.10/00 and -5.50/00 to -5.70/00, respectively, were observed in the 80Se/76Se ratio. These isotopic fractionations did not depend significantly on initial Se concentrations, which were varied from 22 μg/l to 8 mg/l, or on geochemical differences among the sediments. These results provide estimates of Se isotope fractionation in organic-rich wetland environments but may not be appropriate for substrate-poor aquifers and marine sediments.

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

USGS Publications Warehouse

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.; Zawislanski, P.T.

1999-01-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are needed to confirm this preliminary assessment. We have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields ??0.2??? precision on 80Se/76Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 ??g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.

1999-09-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. The authors report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are neededmore » to confirm this preliminary assessment. The authors have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields {+-}0.2% precision on {sup 80}Se/{sup 76}Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 {micro}g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.« less

Semiconductor-metal transition of Se in Ru-Se Catalyst Nanoparticles

NASA Astrophysics Data System (ADS)

Babu, P. K.; Lewera, Adam; Oldfield, Eric; Wieckowski, Andrzej

2009-03-01

Ru-Se composite nanoparticles are promising catalysts for the oxygen reduction reaction (ORR) in fuel cells. Though the role of Se in enhancing the chemical stability of Ru nanoparticles is well established, the microscopic nature of Ru-Se interaction was not clearly understood. We carried out a combined investigation of ^77Se NMR and XPS on Ru-Se nanoparticles and our results indicate that Se, a semiconductor in elemental form, becomes metallic when interacting with Ru. ^77Se spin-lattice relaxation rates are found to be proportional to T, the well-known Korringa behavior characteristic of metals. The NMR results are supported by the XPS binding energy shifts which suggest that a possible Ru->Se charge transfer could be responsible for the semiconductor->metal transition of Se which also makes Ru less susceptible to oxidation during ORR.

A new methodology involving stable isotope tracer to compare short- and long- term selenium mobility in soils

NASA Astrophysics Data System (ADS)

Tolu, Julie; Thiry, Yves; Potin-gautier, Martine; Le hécho, Isabelle; Bueno, Maïté

2013-04-01

Selenium is an element of environmental concern given its dual beneficial and toxic character to animal and human health. Its radioactive isotope 79Se, a fission product of 235U, is considered critical in safety assessment of nuclear waste repositories in case of leakage and hypothetical soil contamination. Therefore, Se species transformations and interactions with soil components have to be clearly understood to predict its dispersion in the biosphere (e.g., accumulation in soils, migration to waters, transfer to living organisms). While natural Se interactions with soils run over centuries to millennia time scales, transformations and partitioning are generally studied with short-term experiments (often inferior to 1 month) after Se addition. The influence of slower, long-term processes involved in Se speciation and mobility in soils is thus not properly accounted for. We tested if using ambient Se would be relevant for long-term risk assessment while added Se would be more representative of short-term contamination impact. For that purpose, we developed a new methodology to trace the differential reactivity of ambient and spiked Se at trace level (µg kg-1) in soils. It combined the use of a stable isotopically enriched tracer with our previous published analytical method based on specific extractions and HPLC-ICP-MS to determine trace Se species partition in different soil phases. Given that soil extracts contains very high concentrations of various elements interfering Se (e.g., Fe, Cl, Br), the ICP-MS parameters and mathematical corrections were optimized to cope with such interferences. Following optimization, three correct and accurate (<2%) isotope ratios were obtained with 77Se, 78Se, 80Se and 82Se. The optimized method was then applied to an arable and a forest soil submitted to an aging process (drying/wetting cycles) during three months, to which 77Se(IV) was previously added. The results showed that ambient Se was at steady state in terms of water leachability, partition between soil solid phases (exchangeable Se and Se associated to organic matter) and speciation. At the opposite, the retention strength, solid phase partition and speciation of 77Se(IV) were modified during the experiment time-course and presented different kinetics. 77Se(IV) behavior tended to be similar to the one of ambient Se but still remained less strongly retained and chemically transformed at three months. We concluded that kinetically limited processes are involved in Se retention and transformation in soils and that commonly used short-term experiments (<1 month) do not consider them properly. Otherwise, it seems more judicious to study ambient Se to infer the processes and parameters used in long-term risk assessment modeling. Since three correct and accurate Se isotope ratios were obtained, this new methodology can be further used to simultaneous monitor the reactivity of three different Se forms (e.g., added Se(IV), Se(VI) or Se(0), ambient Se), that will be useful for both soil Se contamination and supplementation contexts.

Growth process and magnetic properties of α-FeSe nanostructures

NASA Astrophysics Data System (ADS)

Li, S. J.; Li, D.; Jiang, J. J.; Liu, G. B.; Ma, S.; Liu, W.; Zhang, Z. D.

2014-05-01

Growth process and magnetic properties of PbO-type α-FexSe nanostructures with shape changing from nanocacti to nanopetals and then to nanosheets are investigated. With iron acetylacetonate [Fe(acac)3] and Se powder as raw materials, the diffusion process of Fe atoms dominates the synthesis of α-FexSe nanocacti following phase transitions from FeSe2 to Fe3Se4 and finally to α-FexSe. When a mixed solution containing Se precursor and Fe(acac)3 was used as the raw material, the formation of FeSe2 and Fe3Se4 can be avoided and, bended α-FexSe nanopetals can be prepared at 345 °C, which became flat nanosheets with a [001] preferred orientation as extending the reaction time from 1 to 4 h. No superconducting transition occurs in the α-FexSe (0.84 ≤ x ≤ 1.05) nanostructures due to composition heterogeneity or size effect. Magnetic measurements indicate that an antiferromagnetic component with a Néel point at about 45 K dominates the magnetic properties of the α-Fe0.87Se nanosheets.

Distribution of soil selenium in China is potentially controlled by deposition and volatilization?

PubMed Central

Sun, Guo-Xin; Meharg, Andrew A.; Li, Gang; Chen, Zheng; Yang, Lei; Chen, Song-Can; Zhu, Yong-Guan

2016-01-01

Elucidating the environmental drivers of selenium (Se) spatial distribution in soils at a continental scale is essential to better understand it’s biogeochemical cycling to improve Se transfer into diets. Through modelling Se biogeochemistry in China we found that deposition and volatilization are key factors controlling distribution in surface soil, rather than bedrock-derived Se (<0.1 mg/kg). Wet deposition associated with the East Asian summer monsoon, and dry deposition associated with the East Asian winter monsoon, are responsible for dominant Se inputs into northwest and southeast China, respectively. In Central China the rate of soil Se volatilization is similar to that of Se deposition, suggesting that Se volatilization offsets it’s deposition, resulting in negligible net Se input in soil. Selenium in surface soil at Central China is roughly equal to low petrogenic Se, which is the main reason for the presence of the Se poor belt. We suggest that both deposition and volatilization of Se could play a key role in Se balance in other terrestrial environments worldwide. PMID:26883576

Isolation, purification and characterisation of selenium-containing polysaccharides and proteins in selenium-enriched Radix puerariae.

PubMed

Zou, Ye; Zhao, Ting; Mao, Guanghua; Zhang, Min; Zheng, Daheng; Feng, Weiwei; Wang, Wei; Wu, Xiangyang; Yang, Liuqing

2014-01-30

Selenium (Se) is an essential dietary mineral and Radix puerariae (RP) (the dried root of Pueraria lobata Willd.) is a botanical supplement widely used as a nutraceutical. Food enriched with Se provides a feasible and economic approach for production of organic Se compounds. However, little is known about Se-enriched RP and the structure of Se-containing polysaccharides and proteins derived from Se-enriched RP. The organic form of Se accounted for 82.42% of total content. Purification by DEAE-52 and Sephadex G-100 column chromatography yielded three single fractions--RP-SeP-11, RP-SeP-22 and RP-SeP-33--with Se contents of 0.9562 × 10⁻³, 0.6113 × 10⁻³ and 0.3827 × 10⁻³ g kg⁻¹, respectively. RP-SeP-11 (3.5 kDa) was made of glucose, RP-SeP-22 (19.6 kDa) was composed of xylose and glucose, and RP-SeP-33 (97.9 kDa) was made up galactose, mannose and glucose. Two Se-containing proteins were obtained with Se content of 3.175 × 10⁻³ and 4.328 × 10⁻³ g kg⁻¹, respectively. One appeared as three subunits with molecular masses of 43.0, 29.0 and 17.8 kDa while the other appeared as two subunits with molecular masses of 43.0 and 26.3 kDa. The results provide a basis for promoting the utilisation of RP resources enriched with Se as a promising tool for the food industry and are significant for its contribution to Se biochemistry in plants. © 2013 Society of Chemical Industry.

Two-dimensional GaSe/MoSe 2 misfit bilayer heterojunctions by van der Waals epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xufan; Lin, Ming-Wei; Lin, Junhao

Two-dimensional (2D) heterostructures hold the promise for future atomically-thin electronics and optoelectronics due to their diverse functionalities. While heterostructures consisting of different transition metal dichacolgenide monolayers with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) or edge epitaxy, constructing heterostructures from monolayers of layered semiconductors with large lattice misfits still remains challenging. Here, we report the growth of monolayer GaSe/MoSe 2 heterostructures with large lattice misfit by two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe 2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientationmore » between the two layers, forming an incommensurate vdW heterostructure. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe 2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe 2 monolayer domains in lateral GaSe/MoSe 2 heterostructures, GaSe monolayers are found to overgrow MoSe 2 during CVD, forming a stripe of vertically stacked vdW heterostructure at the crystal interface. Such vertically-stacked vdW GaSe/MoSe 2 heterostructures are shown to form p-n junctions with effective transport and separation of photo-generated charge carriers between layers, resulting in a gate-tunable photovoltaic response. In conclusion, these GaSe/MoSe 2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.« less

[Preventive effects of 4 Se-enriched plants on rat stomach cancer induced by MNNG 2. Safety of different selenium resources for prevention of stomach cancer].

PubMed

Yang, Wenjie; Chen, Jing; Li, Weidong; Chen, Xiaobin

2008-01-01

To guide the application of selenium (Se) in the prevention of human chronic diseases, the safety of different Se resources (selenite, Se-enriched garlic, Se-enriched broccoli, Se-enriched green kale and Se-enriched red kale) was investigated. Ninety rats were fed the basal diet for a week, divided equally into the control, N-methyl- N'-nitro-N-nitrosoguanidine (MNNG) and seven Se treatment groups. Rats were daily given 15 mg/kg bw of MNNG for ten days except those in the control group, and rats in seven Se supplementation groups were daily given 75 microg/kg bw or 150 microg/kg bw sodium selenite solution, 150 or 300 microg/kg bw Se as of Se-enriched plant suspension by gavage for 17 weeks. Rats were sacrificed at the end of 18th week, the liver glutathione S-transferase (GST), serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were detected. Rats were given with the basal diet and water freely during the experiment. The data was statistically analyzed by SPSS 12.0 software. All rats in Se 75 microg/kg bw of Se as sodium selenite group died within 6 weeks, the body weights of rats in 75 microg/kg bw of Se as sodium selenite group were significantly lower than those of rats in other groups, the serum AST and ALT activities of rats in 75 microg/kg bw of Se as sodium selenite group were significantly higher than those of rats in other groups, and only the Se supplementation of 75 microg/kg bw of Se as selenite led to rat liver pathological change. Selenite is at least 4 times as toxic as Se-enriched higher plants selected in this experiment.

Flow injection for the determination of Se(IV) and Se(VI) by hydride generation atomic absorption spectrometry with microwave oven on-line prereduction of Se(VI) to Se(IV)

NASA Astrophysics Data System (ADS)

Burguera, J. L.; Carrero, P.; Burguera, M.; Rondon, C.; Brunetto, M. R.; Gallignani, M.

1996-12-01

An on-line flow injection system has been developed for the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters by hydride generation atomic absorption spectrometry with microwave-aided heating prereduction of Se(VI) to Se(IV). The samples and the prereductant solutions (4 mol l -1 HCl for Se(IV) and 12 mol l -1 HCl for Se(VI)) which circulated in a closed-flow circuit were injected by means of a time-based injector. This mixture was displaced by a carrier solution of 1% v/v of hydrochloric acid through a PTFE coil located inside the focused microwave oven and mixed downstream with a borohydride solution to generate the hydride. The linear ranges were 0-120 and 0-100 μg l -1 of Se(IV) and Se(VI), respectively. The detection limits were 1.0 μg l -1 for Se(IV) and 1.5 μg l -1 for Se(VI). The precision (about 2.0-2.5% RSD) and recoveries (96-98% for Se(IV) and 94-98% for Se(VI)) were good. Total selenium values were also obtained by electrothermal atomic absorption spectrometry which agreed with the content of both selenium species. The sample throughput was about 50 measurements per hour. The main advantage of the method is that the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters is performed in a closed system with a minimum sample manipulation, exposure to the environment, minimum sample waste and operator attention.

Selenium bioavailability from soy protein isolate and tofu in rats fed a torula yeast-based diet.

PubMed

Yan, Lin; Graef, George L; Reeves, Philip G; Johnson, LuAnn K

2009-12-23

Selenium (Se) is an essential nutrient, and soy is a major plant source of dietary protein to humans. The United States produces one-third of the world's soybeans, and the Se-rich Northern Plains produce a large share of the nation's soybeans. The present study used a rat model to determine the bioavailability of Se from a protein isolate and tofu (bean curd) prepared from a soybean cultivar we recently developed specifically for food grade markets. The soybean seeds contained 2.91 mg Se/kg. Male Sprague-Dawley rats were depleted of Se by feeding them a 30% Torula yeast-based diet containing 5 microg Se/kg; after 56 days, they were replenished of Se for an additional 50 days by feeding them the same diet supplemented with 20, 30, or 40 microg Se/kg from soy protein isolate or tofu. l-Selenomethionine (SeMet) was used as a reference. Selenium bioavailability was determined on the basis of the responses of Se-dependent enzyme activities and tissue Se contents, comparing those responses for each soy product to those for SeMet using a slope-ratio method. Dietary supplementation with the protein isolate or tofu resulted in dose-dependent increases in glutathione peroxidase activities in blood and liver and thioredoxin reductase activity in liver, as well as dose-dependent increases in the Se contents of plasma, liver, muscle, and kidneys. These responses indicated an overall bioavailability of approximately 97% for Se from both the protein isolate and tofu, relative to SeMet. These results demonstrate that Se from this soybean cultivar is highly bioavailable in this model and that high-Se soybeans can be good dietary sources of Se.

Two-dimensional GaSe/MoSe 2 misfit bilayer heterojunctions by van der Waals epitaxy

DOE PAGES

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; ...

2016-04-01

Two-dimensional (2D) heterostructures hold the promise for future atomically-thin electronics and optoelectronics due to their diverse functionalities. While heterostructures consisting of different transition metal dichacolgenide monolayers with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) or edge epitaxy, constructing heterostructures from monolayers of layered semiconductors with large lattice misfits still remains challenging. Here, we report the growth of monolayer GaSe/MoSe 2 heterostructures with large lattice misfit by two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe 2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientationmore » between the two layers, forming an incommensurate vdW heterostructure. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe 2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe 2 monolayer domains in lateral GaSe/MoSe 2 heterostructures, GaSe monolayers are found to overgrow MoSe 2 during CVD, forming a stripe of vertically stacked vdW heterostructure at the crystal interface. Such vertically-stacked vdW GaSe/MoSe 2 heterostructures are shown to form p-n junctions with effective transport and separation of photo-generated charge carriers between layers, resulting in a gate-tunable photovoltaic response. In conclusion, these GaSe/MoSe 2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.« less

A comparison of fate and toxicity of selenite, biogenically, and chemically synthesized selenium nanoparticles to zebrafish (Danio rerio) embryogenesis.

PubMed

Mal, Joyabrata; Veneman, Wouter J; Nancharaiah, Y V; van Hullebusch, Eric D; Peijnenburg, Willie J G M; Vijver, Martina G; Lens, Piet N L

2017-02-01

Microbial reduction of selenium (Se) oxyanions to elemental Se is a promising technology for bioremediation and treatment of Se wastewaters. But a fraction of biogenic nano-Selenium (nano-Se b ) formed in bioreactors remains suspended in the treated waters, thus entering the aquatic environment. The present study investigated the toxicity of nano-Se b formed by anaerobic granular sludge biofilms on zebrafish embryos in comparison with selenite and chemogenic nano-Se (nano-Se c ). The nano-Se b formed by granular sludge biofilms showed a LC 50 value of 1.77 mg/L, which was 3.2-fold less toxic to zebrafish embryos than selenite (LC 50  =   0.55 mg/L) and 10-fold less toxic than bovine serum albumin stabilized nano-Se c (LC 50  =   0.16 mg/L). Smaller (nano-Se cs ; particle diameter range: 25-80 nm) and larger (nano-Se cl ; particle diameter range: 50-250 nm) sized chemically synthesized nano-Se c particles showed comparable toxicity on zebrafish embryos. The lower toxicity of nano-Se b in comparison with nano-Se c was analyzed in terms of the stabilizing organic layer. The results confirmed that the organic layer extracted from the nano-Se b consisted of components of the extracellular polymeric substances (EPS) matrix, which govern the physiochemical stability and surface properties like ζ-potential of nano-Se b . Based on the data, it is contented that the presence of humic acid like substances of EPS on the surface of nano-Se b plays a major role in lowering the bioavailability (uptake) and toxicity of nano-Se b by decreasing the interactions between nanoparticles and embryos.

Spatial Imaging, Speciation, and Quantification of Selenium in theHyperaccumulator Plants Astragalus bisulcatus and Stanleya pinnata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, J.L.; Zhang, L.H.; Marcus, M.A.

2006-09-01

Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and {gamma}-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in additionmore » to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism.« less

Effects of feeding pregnant beef cows selenium-enriched alfalfa hay on selenium status and antibody titers in their newborn calves.

PubMed

Wallace, L G; Bobe, G; Vorachek, W R; Dolan, B P; Estill, C T; Pirelli, G J; Hall, J A

2017-06-01

In newborn dairy calves, it has been demonstrated that supranutritional maternal and colostral Se supplementation using Se yeast or sodium selenite, respectively, improves passive transfer of IgG. In beef cattle, agronomic biofortification with Se is a more practical alternative for Se supplementation, whereby the Se concentration of hay is increased through the use of Se-containing fertilizer amendments. It has been previously demonstrated that agronomic Se biofortification is an effective strategy to improve immunity and performance in Se-replete weaned beef calves. The objective of this experiment was to determine the effects of feeding beef cows Se-enriched alfalfa () hay during the last 8 to 12 wk of gestation on passive transfer of antibodies to calves. At 10 wk ± 16 d before calving, 45 cows were assigned to 1 of 3 treatment groups with 3 pens (5 cows/pen) per treatment: Control cows were fed non-Se-fortified alfalfa hay plus a mineral supplement containing 120 mg/kg Se from sodium selenite, Med-Se cows were fed alfalfa hay fertilized with 45.0 g Se/ha as sodium selenate, and High-Se cows were fed alfalfa hay fertilized with 89.9 g Se/ha as sodium selenate; both the Med-Se and the High-Se groups received mineral supplement without added Se. Colostrum and whole blood (WB) were collected from cows at calving, and WB was collected from calves within 2 h of calving and at 12, 24, 36, and 48 h of age. Concentrations of IgG1 and J-5 antibody in cow colostrum and calf serum were quantified using ELISA procedures. Selenium concentrations linearly increased in WB ( < 0.001) and colostrum ( < 0.001) of cows and in WB of newborn calves ( < 0.001) with increasing Se concentration in alfalfa hay. Colostrum concentrations of IgG1 ( = 0.03) were increased in cows fed Se-biofortified alfalfa hay, but J-5 antibody ( = 0.43) concentrations were not. Calf serum IgG1 ( = 0.43) and J-5 antibody ( = 0.44) concentrations during the first 48 h of age were not affected by prior Se treatment of cows. These data suggest that feeding Se-biofortified alfalfa hay promotes the accumulation of Se and antibodies in colostrum but does not affect short-term serum antibody concentrations in calves.

Thermoelectric prospects of chemically deposited PbSe and SnSe thin films

NASA Astrophysics Data System (ADS)

Nair, P. K.; Martínez, Ana Karen; Rosa García Angelmo, Ana; Barrios Salgado, Enue; Nair, M. T. S.

2018-03-01

Thin films of PbSe of 400-600 nm in thickness, were obtained via chemical deposition from a solution containing lead nitrate, thiourea and selenosufate. SnSe thin films of 90-180 nm in thickness, were also obtained by chemical deposition from a solution containing selenosulfate. Optical and electrical properties of these thin films were significantly altered by heating them in selenium vapor at 300 °C. Thin film PbSe has a bandgap (Eg) of 1.17 eV (direct gap, forbidden transitions), which decreases to 0.77 eV when it has been heated. Its electrical conductivity (σ) is p-type: 0.18 Ω-1 cm-1 (as-prepared), and 6.4 Ω-1 cm-1 when heated. Thin film SnSe is of orthorhombic crystalline structure which remains stable when heated at 300 °C, but its Eg increases from 1.12 eV (indirect) in as-prepared film to 1.5 eV (direct, forbidden transitions) upon heating. Its electrical conductivity is p-type, which increases from 0.3 Ω-1 cm-1 (as-prepared) to 1 Ω-1 cm-1 when heated (without Se-vapor). When SnSe film is heated at 300 °C in the presence of Se-vapor, they transform to SnSe2, with Eg of 1.5 eV (direct, forbidden) with n-type electrical conductivity, 11 Ω-1 cm-1. The Seebeck coefficient for the PbSe films is: +0.55 mV K-1 (as prepared) and +0.275 mV K-1 (heated); for SnSe films it is: +0.3 mV K-1 (as prepared) and +0.20 mV K-1 (heated); and for SnSe2 film, - 0.35 mV K-1. A five-element PbSe-SnSe2-PbSe-SnSe2-PbSe thermoelectric device demonstrated 50 mV for a temperature difference ΔT = 20 °C (2.5 mV K-1). For SnSe-SnSe2-SnSe-SnSe2-SnSe device, the value is 15 mV for ΔT = 20 °C (0.75 mV K-1). Prospect of these thin films in thermoelectric devices of hybrid materials, in which the coatings may be applied on distinct substrate and geometries is attractive.

Multiple sources of selenium in ancient seafloor hydrothermal systems: Compositional and Se, S, and Pb isotopic evidence from volcanic-hosted and volcanic-sediment-hosted massive sulfide deposits of the Finlayson Lake District, Yukon, Canada

NASA Astrophysics Data System (ADS)

Layton-Matthews, Daniel; Leybourne, Matthew I.; Peter, Jan M.; Scott, Steven D.; Cousens, Brian; Eglington, Bruce M.

2013-09-01

Volcanic-hosted massive sulfide (VHMS) and volcanic-sediment-hosted massive sulfide (VSHMS; i.e., hosted by both volcanic and sedimentary rocks) deposits in the Finlayson Lake District, Yukon, Canada, provide a unique opportunity to study the influence of seafloor and sub-seafloor hydrothermal processes on the formation of Se-poor (GP4F VHMS deposit; 7 ppm Se average), intermediate (Kudz Ze Kayah—KZK VHMS deposit; 200 ppm Se average), and Se-enriched (Wolverine VSHMS deposit; 1100 ppm Se average) mineralization. All three deposits are hosted by mid-Paleozoic (˜360-346 Ma) felsic volcanic rocks, but only the Wolverine deposit has voluminous coeval carbonaceous argillites (black shales) in the host rock package. Here we report the first application of Se isotope analyses to ancient seafloor mineralization and use these data, in conjunction with Pb and S isotope analyses, to better understand the source(s) and depositional process(es) of Se within VHMS and VSHMS systems. The wide range of δ82Se (-10.2‰ to 1.3‰, relative to NIST 3149), δ34S (+2.0‰ to +12.8‰ CDT), and elevated Se contents (up to 5865 ppm) within the Wolverine deposit contrast with the narrower range of δ82Se (-3.8‰ to -0.5‰), δ34S (9.8‰ to 13.0‰), and lower Se contents (200 ppm average) of the KZK deposit. The Wolverine and KZK deposits have similar sulfide depositional histories (i.e., deposition at the seafloor, with concomitant zone refining). The Se in the KZK deposit is magmatic (leaching or degassing) in origin, whereas the Wolverine deposit requires an additional large isotopically negative Se source (i.e. ˜-15‰ δ82Se). The negative δ82Se values for the Wolverine deposit are at the extreme light end for measured terrestrial samples, and the lightest observed for hypogene sulfide minerals, but are within calculated equilibrium values of δ82Se relative to NIST 3149 (˜30‰ at 25 °C between SeO4 and Se2-). We propose that the most negative Se isotope values at the Wolverine deposit record the δ82Se of the Se-source, and that the wide range in δ82Se values results from the combined effects of thermal and chemical degradation and Se-loss from the carbonaceous argillite source to a hydrothermal fluid (including magmatic Se i.e., leached and/or magmatic-hydrothermal) with deposition at or near the paleoseafloor. Pristine unaltered black shales show little variation in δ82Se relative to bulk earth; Se accumulation and fractionation to more negative isotopic values is interpreted to have been produced by post-sediment deposition, but pre-ore stage, reduction of seawater Se within the black shales.

NiSe-Ni0.85 Se Heterostructure Nanoflake Arrays on Carbon Paper as Efficient Electrocatalysts for Overall Water Splitting.

PubMed

Chen, Yajie; Ren, Zhiyu; Fu, Huiying; Zhang, Xin; Tian, Guohui; Fu, Honggang

2018-06-01

Fabricating cost-effective, bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in basic media is critical for renewable energy generation. Here, NiSe/CP, Ni 0.85 Se/CP, and NiSe-Ni 0.85 Se/CP heterostructure catalysts with different phase constitutions are successfully prepared through in situ selenylation of a NiO nanoflake array oriented on carbon paper (CP) by tuning the original Ni/Se molar ratio of the raw materials. The relationship between the crystal phase component and electrocatalytic activity is systematically studied. Benefiting from the synergetic effect of the intrinsic metallic state, facile charge transport, abundant catalytic active sites, and multiple electrolyte transmission paths, the optimized NiSe-Ni 0.85 Se/CP exhibits a remarkably higher catalytic activity for both the HER and OER than single-phase NiSe/CP and Ni 0.85 Se/CP. A current density of 10 mA cm -2 at 1.62 V and a high stability can be obtained by using NiSe-Ni 0.85 Se/CP as both the cathode and anode for overall water splitting under alkaline conditions. Density functional theory calculations confirm that H and OH - can be more easily adsorbed on NiSe-Ni 0.85 Se than on NiSe and Ni 0.85 Se. This study paves the way for enhancing the overall water splitting performance of nickel selenides by fabricating heterophase junctions using nickel selenides with different phases. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts.

PubMed

Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

2013-10-21

Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields.

Phototransistor based on single In2Se3 nanosheets

NASA Astrophysics Data System (ADS)

Li, Qin-Liang; Liu, Chang-Hai; Nie, Yu-Ting; Chen, Wen-Hua; Gao, Xu; Sun, Xu-Hui; Wang, Sui-Dong

2014-11-01

Micrometer-sized single-crystalline In2Se3 nanosheets are synthesized by epitaxial growth from In2Se3 nanowires. The In2Se3 nanosheets possess anisotropic structural configuration with intralayer covalent bonding and interlayer van der Waals bonding. Phototransistors based on the In2Se3 nanosheets are realized, and the devices show high photoresponsivity and high photo On/Off ratio up to two orders. The photo-gating effect can be modulated by the gate bias, indicating potential utility of the In2Se3 nanosheets in a variety of optoelectronic applications.Micrometer-sized single-crystalline In2Se3 nanosheets are synthesized by epitaxial growth from In2Se3 nanowires. The In2Se3 nanosheets possess anisotropic structural configuration with intralayer covalent bonding and interlayer van der Waals bonding. Phototransistors based on the In2Se3 nanosheets are realized, and the devices show high photoresponsivity and high photo On/Off ratio up to two orders. The photo-gating effect can be modulated by the gate bias, indicating potential utility of the In2Se3 nanosheets in a variety of optoelectronic applications. Electronic supplementary information (ESI) available: SEM images of typical In2Se3 nanosheets, TEM-EDX spectrum of single In2Se3 nanosheets, STEM image and elemental mapping of an In2Se3 nanosheet, Scherrer sizes of In2Se3 nanosheets derived from the XRD pattern, statistics of In2Se3 nanosheet thickness, and photoresponse of an In2Se3 nanosheet phototransistor. See DOI: 10.1039/c4nr04404e

Effective mRNA Inhibition in PANC-1 Cells in Vitro Mediated via an mPEG-SeSe-PEI Delivery System.

PubMed

Zhang, Yuefeng; Yang, Bin; Liu, Yajie; Qin, Wenjie; Li, Chao; Wang, Lantian; Zheng, Wen; Wu, Yulian

2016-05-01

RNA interference (RNAi)-mediated gene therapy is a promising approach to cure various diseases. However, developing an effective, safe, specific RNAi delivery system remains a major challenge. In this study, a novel redox-responsive polyetherimide (PEI)-based nanovector, mPEG-SeSe-PEI, was developed and its efficacy evaluated. We prepared three mPEG-SeSe-PEI vector candidates for small interfering glyceraldehyde-3-phosphate dehydrogenase (siGADPH) and determined their physiochemical properties and transfection efficiency using flow cytometry and PEG11.6-SeSe-PEI polymer. We investigated the silencing efficacy of GADPH mRNA expression in PANC-1 cells and observed that PEG11.6-SeSe-PEI/siGADPH (N/P ratio=10) polyplexes possessed the appropriate size and zeta-potential and exhibited excellent in vitro gene silencing effects with the least cytotoxicity in PANC-1 cells. In conclusion, we present PEG11.6-SeSe-PEI as a potential therapeutic gene delivery system for small interfering RNA (siRNA).

Effects of Different Forms of Selenium Fertilizers on Se Accumulation, Distribution, and Residual Effect in Winter Wheat-Summer Maize Rotation System.

PubMed

Wang, Qi; Yu, Yao; Li, Jixiang; Wan, Yanan; Huang, Qingqing; Guo, Yanbin; Li, Huafen

2017-02-15

Foliar Se fertilizers were applied to investigate the effects of Se forms on Se accumulation and distribution in the wheat-maize rotation system and residual concentration of Se in subsequent crops. Sodium selenite, sodium selenate, selenomethionine, chemical nano-Se, humic acid + sodium selenite, and compound fertilizer + sodium selenite were applied once at the flowering stage of wheat (30 g ha -1 ) and at the bell stage of maize (60 g ha -1 ). Compared with the control treatment, foliar Se applications significant increased the grain Se concentration of wheat and maize by 0.02-0.31 and 0.07-1.09 mg kg -1 , respectively. Wheat and maize grain Se recoveries were 3.0-10.4 and 4.1-18.5%, respectively. However, Se concentrations in the grain of subsequent wheat and maize significantly decreased by 77.9 and 91.2%, respectively. The change of Se concentration in soil was a dynamic process with Se depletion after harvest of maize.

Thioether coordination to divalent selenium halide acceptors--synthesis, properties and structures.

PubMed

Jolleys, Andrew; Levason, William; Reid, Gillian

2013-02-28

The tetravalent SeCl(4) and SeBr(4) are reduced in the presence of thioether ligands L (SMe(2), tht) or L-L (MeS(CH(2))(n)SMe (n = 2 or 3), o-C(6)H(4)(SMe)(2)) in MeCN solution at 0 °C, forming Se(II) thioether complexes, including the crystallographically characterised halo-bridged chain polymers [SeX(2)(SMe(2))] (X = Cl or Br), molecular trans-[SeX(2)(tht)(2)], cis-[SeBr(2){MeS(CH(2))(2)SMe}] and the thioether-bridged polymer [SeBr(2){MeS(CH(2))(3)SMe}], as the main products, together with halogenated ligand. The [SeX(2)(L)(2)] and [SeX(2)(L-L)] complexes are all based upon distorted square planar coordination, with two Se-based lone pairs assumed to occupy the (vacant) axial sites, and Se-S bond distances of ca. 2.4-2.6 Å. The 1:1 species [SeX(2)(SMe(2))] are T-shaped with trans X groups and weak intermolecular SeX contacts. The SeCl(2)-thioether complexes are less stable than the bromides, both in solution in CH(2)Cl(2) and as solids at ambient temperature. Reaction of SeBr(4) with o-C(6)H(4)(SMe(2))(2) leads to the red complex cis-[SeBr(2){κ(1)-o-C(6)H(4)(SMe)(2)}(2)] as the major product; together with a minor (yellow) product formed via bromination of the aromatic ring, [SeBr(2){4-Br-1,2-(SMe)(2)-C(6)H(3)}(2)]. The crystal structure confirms a V-shaped SeBr(2) unit with long (weak) κ(1)-interactions to one S donor (meta to the Br) from two brominated ligands--an extremely rare coordination mode for an o-phenylene dithioether. Similar reaction of o-C(6)H(4)(SMe(2))(2) with SeCl(4) leads to several species, including monosulfonium cation, [1](+) formed by coupling of one thioether group to the C4-position of the phenylene backbone in an adjacent molecule, confirmed crystallographically. Carbon-sulfur coupling is also evident in the reaction of SeX(4) with o-C(6)H(4)(CH(2)SMe)(2), leading to two related cyclic sulfonium species, [2](+) and [3](+), which were structurally characterised as [SeBr(4)](2-) and [Se(2)Cl(6)](2-) salts respectively. Reaction of SeX(4) with SeMe(2) leads to halogenation of the ligand to form Me(2)SeX(2) and reduction of the SeX(4) to elemental selenium.

Constitution diagram on the system TlSe-Tb-Se

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guseinov, G.D.; Kerimova, E.M.; Agamaliev, D.G.

1988-03-01

The constitution diagram of the system TlSe-TbSe was constructed based on the results of differential-thermal, x-ray phase, and microstructural analyses and measurements of the microhardness. The compound TlTbSe/sub 2/, forming by a peritectic reaction, was observed. It was established that the solubility of TbSe in TlSe at room temperature equals 4.0 mole %.

Characterization of a Selenium-Tolerant Rhizosphere Strain from a Novel Se-Hyperaccumulating Plant Cardamine hupingshanesis

PubMed Central

Yuan, Linxi; Luo, Lei; Yin, Xuebin

2014-01-01

A novel selenium- (Se-) hyperaccumulating plant, Cardamine hupingshanesis, accumulating Se as a form of SeCys2, was discovered in Enshi, Hubei, China, which could not be explained by present selenocysteine methyltransferase (SMT) theory. However, it is interesting to investigate if rhizosphere bacteria play some roles during SeCys2 accumulation. Here, one Se-tolerant rhizosphere strain, Microbacterium oxydans, was isolated from C. hupingshanesis. Phylogenetic analysis and 16S rRNA gene sequences determined the strain as a kind of Gram positive bacillus and belonged to the family Brevibacterium frigoritolerans. Furthermore, Se tolerance test indicated the strain could grow in extreme high Se level of 15.0 mg Se L−1. When exposed to 1.5 mg Se L−1, SeCys2 was the predominant Se species in the bacteria, consistent with the Se species in C. hupingshanesis. This coincidence might reveal that this strain played some positive effect in SeCys2 accumulation of C. hupingshanesis. Moreover, when exposed to 1.5 mg Se L−1 or 15.0 mg Se L−1, As absorption diminished in the logarithmic phase. In contrast, As absorption increased when exposed to 7.5 mg Se L−1, indicating As metabolism processes could be affected by Se on this strain. The present study provided a sight on the role of rhizosphere bacteria during Se accumulation for Se-hyperaccumulating plant. PMID:25478582

Selenium is critical for cancer-signaling gene expression but not cell proliferation in human colon Caco-2 cells.

PubMed

Zeng, Huawei; Botnen, James H

2007-01-01

Selenium (Se) is a potential anticarcinogenic nutrient, and the essential role of Se in cell growth is well recognized but certain cancer cells appear to have acquired a survival advantage under conditions of Se-deficiency. To understand the molecular basis of Se-anticancer effects at nutritional doses (nmol/L) for cultured cells, we generated Se-deficient colon Caco-2 cells by gradually reducing serum in media because serum contains a trace amount of Se. The glutathione peroxidase (GPx) activity of Se-deficient Caco-2 cells was 10.8 mU/mg protein compared to 133.6 approximately 146.3 mU/mg protein in Caco-2 cells supplemented with 500 nmol/L selenite, SeMSC or SeMet (three tested Se-chemical forms) after 7-d culture in serum free media. Interestingly, there were no detectable differences in cell growth, cell cycle progression between Se-deficient cells and cells supplemented with 500 nmol/L Se. To examine differential cancer signaling-gene expression between Se-deficient and Se-supplemented cells, we employed a cancer signal pathway-specific array assay coupled with the real time PCR analysis. Our data demonstrate that although Caco-2 cells are resistant to Se deprivation, Se may exert its anticancer property through increasing the expression of humoral defense gene (A2M) and tumor suppressor-related genes (IGFBP3, HHIP) while decreasing pro-inflammatory gene (CXC L9, HSPB2) expression.

Effect of adding Te to layered GaSe crystals to increase the van der Waals bonding force

NASA Astrophysics Data System (ADS)

Tanabe, Tadao; Zhao, Shu; Sato, Yohei; Oyama, Yutaka

2017-10-01

The interplanar binding strength of layered GaSe1-xTex crystals was directly measured using a tensile testing machine. The GaSe1-xTex crystals were grown by a low temperature liquid phase solution method under a controlled Se vapor pressure. The stoichiometry-controlled GaSe1-xTex crystal has the ɛ-polytype structure of GaSe, where the Te atoms are substituted for some of the Se atoms in the GaSe crystal. The effect of adding Te on the bonding strength between the GaSe layers was determined from direct measurements of the van der Waals bonding energy. The bonding energy was increased from 0.023 × 106 N/m2 for GaSe to 0.16 × 106 N/m2 for GaSe1-xTex (x = 0.106).

Selenium-assisted controlled growth of graphene-Bi2Se3 nanoplates hybrid Dirac materials by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Sun, Zhencui; Man, Baoyuan; Yang, Cheng; Liu, Mei; Jiang, Shouzhen; Zhang, Chao; Zhang, Jiaxin; Liu, Fuyan; Xu, Yuanyuan

2016-03-01

Se seed layers were used to synthesize the high-quality graphene-Bi2Se3 nanoplates hybrid Dirac materials via chemical vapor deposition (CVD) method. The morphology, crystallization and structural properties of the hybrid Dirac materials were characterized by SEM, EDS, Raman, XRD, AFM and HRTEM. The measurement results verify that the Se seed layer on the graphene surface can effectively saturate the surface dangling bonds of the graphene, which not only impel the uniform Bi2Se3 nanoplates growing along the horizontal direction but also can supply enough Se atoms to fill the Se vacancies. We also demonstrate the Se seed layer can effectively avoid the interaction of Bi2Se3 and the graphene. Further experiments testify the different Se seed layer on the graphene surface can be used to control the density of the Bi2Se3 nanoplates.

Effects of temperature and dissolved oxygen on Se(IV) removal and Se(0) precipitation by Shewanella sp. HN-41.

PubMed

Lee, Ji-Hoon; Han, Jaehong; Choi, Heechul; Hur, Hor-Gil

2007-08-01

Facultative anaerobic Shewanella sp. strain HN-41 was able to utilize selenite (Se(IV)) as a sole electron acceptor for respiration in anaerobic condition, resulting in reduction of Se(IV) and then precipitation of elemental Se nano-sized spherical particles, which were identified using energy-dispersive X-ray spectroscopy and X-ray absorption near-edge structure spectroscopy. When the effects on Se(IV) reduction to elemental Se were studied by varying incubation temperatures and dissolved oxygen contents, Se(IV) reduction occurred more actively with higher removal rate of Se(IV) in aqueous phase and well-shaped spherical Se(0) nanoparticles were formed from the incubations under N(2) (100%) or N(2):O(2) (80%:20%) at 30 degrees C with average diameter values of 181+/-40 nm and 164+/-24 nm, respectively, while relatively less amounts of irregular-shaped Se(0) nanoparticles were produced with negligible amount of Se(IV) reduction and removal under 100% of O(2). The Se particle size distributions based on scanning electron microscopy also showed a general tendency towards decreased Se particle size as oxygen content increased, whereas the particle size seemed uncorrelated to the change in the incubation temperature. These results also suggest that the size-controlled biological Se(0) nanospheres production may be achieved simply by changing the culture conditions.

Anion–Anion Bonding and Topology in Ternary Iridium Seleno–Stannides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trump, Benjamin A.; Tutmaher, Jake A.; McQueen, Tyrel M.

2015-12-21

The synthesis and physical properties of two new and one known Ir–Sn–Se compound are reported. Their crystal structures are elucidated with transmission electron microscopy and powder X-ray diffraction. IrSn0.45Se1.55 is a pyrite phase which consists of tilted corner-sharing IrX6 octahedra with randomly distributed (Sn–Se)4– and (Se–Se)2– dimers. Ir2Sn3Se3 is a known trigonally distorted skutterudite that consists of cooperatively tilted corner-sharing IrSn3Se3 octahedra with ordered (Sn–Se)24– tetramers. Ir2SnSe5 is a layered, distorted β-MnO2 (pyrolusite) structure consisting of a double IrSe6 octrahedral row, corner sharing in the a direction and edge sharing in the b direction. This distorted pyrolusite contains (Se–Se)2– dimersmore » and Se2– anions, and each double row is “capped” with a (Sn–Se)n polymeric chain. Resistivity, specific heat, and magnetization measurements show that all three have insulating and diamagnetic behavior, indicative of low-spin 5d6 Ir3+. Electronic structure calculations on Ir2Sn3Se3 show a single, spherical, nonspin–orbit split valence band and suggest that Ir2Sn3Se3 is topologically nontrivial under tensile strain due to inversion of Ir-d and Se-p states.« less

Speciation of Se and DOC in soil solution and their relation to Se bioavailability.

PubMed

Weng, Liping; Vega, Flora Alonso; Supriatin, Supriatin; Bussink, Wim; Van Riemsdijk, Willem H

2011-01-01

A 0.01 M CaCl(2) extraction is often used to asses the bioavailability of plant nutrients in soils. However, almost no correlation was found between selenium (Se) in the soil extraction and Se content in grass. The recently developed anion Donnan membrane technique was used to analyze chemical speciation of Se in the 0.01 M CaCl(2) extractions of grassland soils and fractionation of DOC (dissolved organic carbon). The results show that most of Se (67-86%) in the extractions (15 samples) are colloidal-sized Se. Only 13-34% of extractable Se are selenate, selenite and small organic Se (<1 nm). Colloidal Se is, most likely, Se bound to or incorporated in colloidal-sized organic matter. The dominant form of small Se compounds (selenate, selenite/small organic compounds) depends on soil. A total of 47-85% of DOC is colloidal-sized and 15-53% are small organic molecules (<1 nm). In combination with soluble S (sulfur) and/or P (phosphor), concentration of small DOC can explain most of the variability of Se content in grass. The results indicate that mineralization of organic Se is the most important factor that controls Se availability in soils. Competition with sulfate and phosphate needs to be taken into account. Further research is needed to verify if concentration of small DOC is a good indicator of mineralization of soil organic matter.

The Interface Structure of FeSe Thin Film on CaF2 Substrate and its Influence on the Superconducting Performance.

PubMed

Qiu, Wenbin; Ma, Zongqing; Patel, Dipak; Sang, Lina; Cai, Chuanbing; Shahriar Al Hossain, Mohammed; Cheng, Zhenxiang; Wang, Xiaolin; Dou, Shi Xue

2017-10-25

The investigations into the interfaces in iron selenide (FeSe) thin films on various substrates have manifested the great potential of showing high-temperature-superconductivity in this unique system. In present work, we obtain FeSe thin films with a series of thicknesses on calcium fluoride (CaF 2 ) (100) substrates and glean the detailed information from the FeSe/CaF 2 interface by using scanning transmission electron microscopy (STEM). Intriguingly, we have found the universal existence of a calcium selenide (CaSe) interlayer with a thickness of approximate 3 nm between FeSe and CaF 2 in all the samples, which is irrelevant to the thickness of FeSe layers. A slight Se deficiency occurs in the FeSe layer due to the formation of CaSe interlayer. This Se deficiency is generally negligible except for the case of the ultrathin FeSe film (8 nm in thickness), in which the stoichiometric deviation from FeSe is big enough to suppress the superconductivity. Meanwhile, in the overly thick FeSe layer (160 nm in thickness), vast precipitates are found and recognized as Fe-rich phases, which brings about degradation in superconductivity. Consequently, the thickness dependence of superconducting transition temperature (T c ) of FeSe thin films is investigated and one of our atmosphere-stable FeSe thin film (127 nm) possesses the highest T c onset /T c zero as 15.1 K/13.4 K on record to date in the class of FeSe thin film with practical thickness. Our results provide a new perspective for exploring the mechanism of superconductivity in FeSe thin film via high-resolution STEM. Moreover, approaches that might improve the quality of FeSe/CaF 2 interfaces are also proposed for further enhancing the superconducting performance in this system.

Comparative study of selenium and selenium nanoparticles with reference to acute toxicity, biochemical attributes, and histopathological response in fish.

PubMed

Kumar, Neeraj; Krishnani, Kishore Kumar; Singh, Narendra Pratap

2018-03-01

Recent studies have demonstrated that selenium (Se) and selenium nanoparticles (Se-NPs) exhibited toxicity at a higher concentration. The lethal concentration of Se and Se-NPs was estimated as 5.29 and 3.97 mg/L at 96 h in Pangasius hypophthalmus. However, the effect of different definite concentration of Se (4.5, 5.0, 5.5, and 6.0 mg/L) and Se-NPs (2.5, 3.0, 3.5, and 4.0 mg/L) was decided for acute experiment. Selenium and Se-NPs alter the biochemical attributes such as anti-oxidative status [catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities], neurotransmitter enzyme, cellular metabolic enzymes, stress marker, and histopathology of P. hypophthalmus in a dose- and time-dependent manner. CAT, SOD, and GST were significantly elevated (p < 0.01) when exposed to Se and Se-NPs, and similarly, a neurotransmitter enzyme (acetylcholine esterase (AChE)) was significantly inhibited in a time- and dose-dependent manner. Further, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and malate hydrogenase were noticeably (p < 0.01) affected by Se and Se-NPs from higher concentration to lower concentration. Stress markers such as cortisol and HSP 70 were drastically enhanced by exposure to Se and Se-NPs. All the cellular metabolic and stress marker parameters were elevated which might be due to hyperaccumulation of Se and Se-NPs in the vital organ and target tissues. The histopathology of liver and gill was also altered such as large vacuole, cloudy swelling, focal necrosis, interstitial edema, necrosis in liver, and thickening of primary lamellae epithelium and curling of secondary lamellae due to Se and Se-NP exposure. The study suggested that essential trace element in both forms (inorganic and nano) at higher concentration in acute exposure of Se and Se-NPs led to pronounced deleterious alteration on histopathology and cellular and metabolic activities of P. hypophthalmus.

Nano-Se Assimilation and Action in Poultry and Other Monogastric Animals: Is Gut Microbiota an Answer?

NASA Astrophysics Data System (ADS)

Surai, Peter F.; Kochish, Ivan I.; Velichko, Oksana A.

2017-12-01

Recently, a comprehensive review paper devoted to roles of nano-Se in livestock and fish nutrition has been published in the Nanoscale Research Letters. The authors described in great details an issue related to nano-Se production and its possible applications in animal industry and medicine. However, molecular mechanisms of nano-Se action were not described and the question of how nano-Se is converted into active selenoproteins is not resolved. It seems likely that the gut microbiota can convert nano-Se into selenite, H2Se or Se-phosphate with the following synthesis of selenoproteins. This possibility needs to be further studied in detail, and advantages and disadvantages of nano-Se as a source of Se in animal/poultry/fish nutrition await critical evaluations.

Speciation of inorganic selenium and selenoamino acids by an HPLC-UV-HG-AFS system.

PubMed

Ipolyi, I; Corns, W; Stockwell, P; Fodor, P

2001-01-01

For the on-line speciation of selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (SeEt), selenite (Se(IV)) and selenate (Se(VI)), a high-performance liquid chromatography-UV irradiation-hydride generation-atomic fluorescence spectro- metric method is described. Separation was carried out on a conventional reversed-phase C18 column modified with didodecyl- dimethylammonium bromide with gradient elution applying two concentrations of ammonium acetate as the mobile phase. UV irradiation and hydride generation parameters were optimized. The obtained detection limits for SeCys, SeMet, SeEt, Se(IV) and Se(VI) were 0.31, 0.43, 0.7, 0.44 and 0.32 ng ml(-1), respectively, using a 100-microl loop. The method was tested with spiked mineral water and two volunteers' urine samples.

Speciation of inorganic selenium and selenoamino acids by an HPLC-UV-HG-AFS system

PubMed Central

Ipolyi, I.; Corns, W.; Stockwell, P.; Fodor, P.

2001-01-01

For the on-line speciation of selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (SeEt), selenite (Se(IV)) and selenate (Se(VI)), a high-performance liquid chromatography-UV irradiation-hydride generation-atomic fluorescence spectro- metric method is described. Separation was carried out on a conventional reversed-phase C18 column modified with didodecyl- dimethylammonium bromide with gradient elution applying two concentrations of ammonium acetate as the mobile phase. UV irradiation and hydride generation parameters were optimized. The obtained detection limits for SeCys, SeMet, SeEt, Se(IV) and Se(VI) were 0.31, 0.43, 0.7, 0.44 and 0.32 ng ml−1, respectively, using a 100-wl loop. The method was tested with spiked mineral water and two volunteers' urine samples. PMID:18924707

Preparation and characterization of selenite substituted hydroxyapatite.

PubMed

Ma, Jun; Wang, Yanhua; Zhou, Lei; Zhang, Shengmin

2013-01-01

Selenite-substituted hydroxyapatite (Se-HA) with different Se/P ratios was synthesized by a co-precipitation method, using sodium selenite (Na2SeO3) as a Se source. Selenium has been incorporated into the hydroxyapatite lattice by partially replacing phosphate (PO4(3-)) groups with selenite (SeO3(2-)) groups. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) techniques reveal that substitutions of phosphate groups by selenite groups cause lower carbonate groups occupying at phosphate sites and change the lattice parameters of hydroxyapatite. The powders obtained are nano-crystalline hydroxyapatite when the Se/P ratios are not more than 0.1. The particle shape of Se-HA has not been altered compared with selenite-free hydroxyapatite but Se-incorporation reduces the crystallite size. The crystallinity was reduced as the Se/P ratios increased until amorphous phase (Se/P=0.3) appeared in the Se-HA powder obtained, and then another crystal phase presented as calcium selenite hydrate (Se/P=10). In addition, the sintering tests show that the Se-HA powders with the Se/P ratio of 0.1 have thermal stability at 900 °C for 2 h; hence they have great potential in the fabrication of bone repair scaffolds. Copyright © 2012 Elsevier B.V. All rights reserved.

Measurement of the half-life of 79Se with accelerator mass spectrometry

DOE PAGES

Dou, Liang; Jiang, Shan; Wang, Xiao-Bo; ...

2014-10-01

The accelerator mass spectrometry (AMS) is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of 79Se. The number of 79Se atoms was determined from measured 79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of 79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an 79Se sample which was cooled for many years to exclude the interference of short-livedmore » nuclides, the extraction of SeO 2 - molecular ions, that results in a suppression of the 79 Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of 79 Se/Se was developed to avoid systematic errors. The results show that 79 Se/Se is (2.35±0.12)×10 -7 in the reference sample and the radioactivity of 79Se is (1.24±0.05) Bq/g, so the half-life of 79Se is (2.78±0.18)×10 5 a.« less

Growth and optical properties of Dy doped and undoped n-type InSe single crystal

NASA Astrophysics Data System (ADS)

Gürbulak, B.

1999-02-01

Undoped n-InSe and Dy doped n-InSe (n-InSe : Dy) single crystals were grown by a method which is similar to direct freezing method. Ingots had no cracks and voids on the surface. There were no processes to polish and clean treatment at cleavage faces of these samples because of the natural mirror-like cleavage faces. The absorption measurements were carried out in n-InSe and n-InSe : Dy samples in the temperature range 10-320 K. The first exciton energies for n=1 were calculated as 1.331, 1.248 eV in n-InSe and were 1.326, 1.244 eV in n-InSe : Dy at 10 and 300 K, respectively. The second exciton energies for n=2 in n-InSe were calculated as 1.346, 1.336 eV and in n-InSe : Dy were 1.340, 1.332 eV at 10 and 80 K, respectively. Binding energies of n-InSe and n-InSe : Dy were calculated as 19.47 and 18.87 meV, respectively. The direct bands gap for n-InSe are 1.350, 1.267 eV and for n-InSe : Dy are 1.344, 1.263 eV at 10, 300 K, respectively.

A method for measurement of ultratrace 79Se with accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Wang, Wei; Guan, Yongjing; He, Ming; Jiang, Shan; Wu, Shaoyong; Li, Chaoli

2010-04-01

79Se is a long-lived fission product with chemical and radiological toxicity. It is one of the radionuclides of interest in nuclear waste disposal due to its potential migration capacity to the surface environment. Furthermore, 79Se is an ideal tracer in biomedicine. One of the major obstacles in the measurement of ultratrace 79Se with AMS is the strong interference from the isobaric nuclide 79Br. This paper presents a new ultra-sensitive method for 79Se measurements with AMS. The novel aspects of our procedures include the extraction of SeO2- molecular ions, that results in a suppression of 79Br background by as much as about five orders of magnitude; the selection of Ag 2SeO 3 as the chemical form of Se in the target sample, that brings about a relatively large and stable SeO2- beam current; and the renovation of the multi-anode detector, that makes 79Se better identified from the interfering nuclide 79Br. By using these procedures, a sensitivity of better than 1.0 × 10 -12 has been achieved for 79Se/Se measurement with the CIAE-AMS system. It is then possible to quantify the tracer 79Se in biological samples. Recently, we are prepared to develop the 79Se-AMS biological tracer methodology.

Selenium speciation in malt, wort, and beer made from selenium-biofortified two-rowed barley grain.

PubMed

Rodrigo, Sara; Santamaria, Oscar; Chen, Yi; McGrath, Steve P; Poblaciones, Maria J

2014-06-25

Selenium (Se) biofortification of barley is a suitable strategy to increase the Se concentration in grain. In the present paper, the suitability of this Se-biofortified grain for making Se-enriched beer is analyzed. The aim of the present study was to evaluate the effect of different Se fertilizer doses (0, 10, and 20 g of Se ha(-1)) and forms (sodium selenate or sodium selenite) on the Se loss during the malting and brewing processes and Se speciation in grain, malt, wort, and beer. Samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS for total Se and speciation. Mashing-lautering was the process with the greatest Se loss (83.8%). After malting and brewing, only 7.3% of the initial Se was retained in beer, mainly in selenite form. Even so, the fertilizer application of sodium selenate at 20 g ha(-1) increased the total Se concentration almost 6-fold in the final beer in comparison to the use of grain derived from unfertilized barley. The present paper provides evidence that the use of Se-biofortified barley grain as a raw material to produce Se-enriched beer is possible, and the results are comparable to other methods in terms of efficiency.

Selenium speciation using capillary electrophoresis coupled with modified electrothermal atomic absorption spectrometry after selective extraction with 5-sulfosalicylic acid functionalized magnetic nanoparticles.

PubMed

Yan, Lizhen; Deng, Biyang; Shen, Caiying; Long, Chanjuan; Deng, Qiufen; Tao, Chunyao

2015-05-22

A new method for selenium speciation in fermented bean curd wastewater and juice was described. This method involved sample extraction with 5-sulfosalicylic acid (SSA)-functionalized silica-coated magnetic nanoparticles (SMNPs), capillary electrophoresis (CE) separation, and online detection with a modified electrothermal atomic absorption spectrometry (ETAAS) system. The modified interface for ETAAS allowed for the introduction of CE effluent directly through the end of the graphite tube. Elimination of the upper injection hole of the graphite tube reduced the loss of the anlayte and enhanced the detection sensitivity. The SSA-SMNPs were synthesized and used to extract trace amounts of selenite [Se(IV)], selenite [Se(VI)], selenomethionine (SeMet), and selenocystine (SeCys2) from dilute samples. The concentration enrichment factors for Se(VI), Se(IV), SeMet, and SeCys2 were 21, 29, 18, and 12, respectively, using the SSA-SMNPs extraction. The limits of detection for Se(VI), Se(IV), SeMet, and SeCys2 were 0.18, 0.17, 0.54, 0.49ngmL(-1), respectively. The RSD values (n=6) of method for intraday were observed between 0.7% and 2.9%. The RSD values of method for interday were less than 3.5%. The linear range of Se(VI) and Se(IV) were in the range of 0.5-200ngmL(-1), and the linear ranges of SeMet and SeCys2 were 2-500 and 2-1000ngmL(-1), respectively. The detection limits of this method were improved by 10 times due to the enrichment by the SSA-SMNP extraction. The contents of Se(VI) and Se(IV) in fermented bean curd wastewater were measured as 3.83 and 2.62ngmL(-1), respectively. The contents of Se(VI), Se(IV), SeMet, and SeCys2 in fermented bean curd juice were determined as 6.39, 4.08, 2.77, and 4.00ngmL(-1), respectively. The recoveries were in the range of 99.14-104.5% and the RSDs (n=6) of recoveries between 0.82% and 3.5%. Copyright © 2015 Elsevier B.V. All rights reserved.

Safe surgery: validation of pre and postoperative checklists.

PubMed

Alpendre, Francine Taporosky; Cruz, Elaine Drehmer de Almeida; Dyniewicz, Ana Maria; Mantovani, Maria de Fátima; Silva, Ana Elisa Bauer de Camargo E; Santos, Gabriela de Souza Dos

2017-07-10

to develop, evaluate and validate a surgical safety checklist for patients in the pre and postoperative periods in surgical hospitalization units. methodological research carried out in a large public teaching hospital in the South of Brazil, with application of the principles of the Safe Surgery Saves Lives Programme of the World Health Organization. The checklist was applied to 16 nurses of 8 surgical units and submitted for validation by a group of eight experts using the Delphi method online. the instrument was validated and it was achieved a mean score ≥1, level of agreement ≥75% and Cronbach's alpha >0.90. The final version included 97 safety indicators organized into six categories: identification, preoperative, immediate postoperative, immediate postoperative, other surgical complications, and hospital discharge. the Surgical Safety Checklist in the Pre and Postoperative periods is another strategy to promote patient safety, as it allows the monitoring of predictive signs and symptoms of surgical complications and the early detection of adverse events. elaborar, avaliar e validar um checklist de segurança cirúrgica para os períodos pré e pós-operatório de unidades de internação cirúrgica. pesquisa metodológica, realizada em hospital de ensino público de grande porte do Sul do Brasil, com aplicação dos fundamentos do Programa Cirurgias Seguras Salvam Vidas da Organização Mundial da Saúde. O checklist foi aplicado a 16 enfermeiros de oito unidades cirúrgicas, e submetido à validação por meio da técnica Delphi on-line com oito especialistas. o instrumento foi validado, obtendo-se ranking médio ≥1, grau de concordância ≥75% e Alfa de Cronbach >0,90. A versão final contemplou 97 indicadores de segurança organizados em seis categorias: identificação, pré-operatório, pós-operatório imediato, pós-operatório mediato, outras complicações cirúrgicas, e alta hospitalar. o Checklist de Segurança Cirúrgica Pré e Pós-Operatório é mais uma estratégia na promoção da segurança do paciente, pois possibilita monitorar sinais e sintomas preditivos de complicações cirúrgicas e detecção precoce de eventos adversos. desarrollar, evaluar y validar un checklist de seguridad quirúrgica para los períodos pre y postoperatorio de unidades de hospitalización quirúrgica.. investigación metodológica llevada a cabo en un amplio hospital público de enseñanza del Sur de Brasil, con aplicación de los principios del Programa de Cirugía Segura Salva Vidas de la Organización Mundial de la Salud. El checklist se aplicó a 16 enfermeros de 8 unidades quirúrgicas y fue sometida a validación por ocho expertos utilizando el método Delphi en línea. el instrumento fue validado y se logró una puntuación media ≥1, grado de acuerdo ≥75% y alfa de Cronbach >0.90. La versión final incluyó 97 indicadores de seguridad organizados en seis categorías: identificación, preoperatorio, postoperatorio inmediato, postoperatorio inmediato, otras complicaciones quirúrgicas y alta hospitalaria. el Checklist de Seguridad Quirúrgica en el Período Pre y Postoperatorio es otra estrategia más para promover la seguridad del paciente, ya que permite monitorear los signos y síntomas predictivos de las complicaciones quirúrgicas y la detección temprana de eventos adversos.

High dietary intake of sodium selenite does not affect gene mutation frequency in rat colon and liver.

PubMed

Zeng, Huawei; Uthus, Eric O; Ross, Sharon A; Davis, Cindy D

2009-10-01

Our previous studies have shown that selenium (Se) is protective against dimethylhydrazine (DMH)-induced preneoplastic colon cancer lesions, and protection against DNA damage has been hypothesized to be one mechanism for the anticancer effect of Se. The present study was designed to determine whether dietary selenite affects somatic mutation frequency in vivo. We used the Big Blue transgenic model to evaluate the in vivo mutation frequency of the cII gene in rats fed either a Se-deficient (0 microg Se/g diet) or Se-supplemented diet (0.2 or 2 microg Se/g diet; n = 3 rats/diet in experiment 1 and n = 5 rats/group in experiment 2) and injected with DMH (25 mg/kg body weight, i.p.). There were no significant differences in body weight between the Se-deficient and Se-supplemented (0.2 or 2 microg Se/g diet) rats, but the activities of liver glutathione peroxidase and thioredoxin reductase and concentration of liver Se were significantly lower (p < 0.0001) in Se-deficient rats compared to rats supplemented with Se. We found no effect of dietary Se on liver 8-hydroxy-2'-deoxyguanosine. Gene mutation frequency was significantly lower in liver (p < 0.001) than that of colon regardless of dietary Se. However, there were no differences in gene mutation frequency in DNA from colon mucosa or liver from rats fed the Se-deficient diet compared to those fed the Se-supplemented (0.2 or 2 microg Se/g diet) diet. Although gene mutations have been implicated in the etiology of cancer, our data suggest that decreasing gene mutation is not likely a key mechanism through which dietary selenite exerts its anticancer action against DMH-induced preneoplastic colon cancer lesions in a Big Blue transgenic rat model.

The Effect of Lactobacillus acidophilus PTCC 1643 on Cultured Intestinal Epithelial Cells Infected with Salmonella enterica serovar Enteritidis.

PubMed

Moshiri, Mona; Dallal, Mohammad Mehdi Soltan; Rezaei, Farhad; Douraghi, Masoumeh; Sharifi, Laleh; Noroozbabaei, Zahra; Gholami, Mehrdad; Mirshafiey, Abbas

2017-02-01

Gastrointestinal disorders caused by Salmonella enterica serovar Enteritidis ( Se sE) are a significant health problem around the globe. Probiotic bacteria have been shown to have positive effects on the immune responses. Lactobacillus acidophilus was examined for its capability to influence the innate immune response of HT29 intestinal epithelial cells towards Se sE. The purpose of this work was to assess the effect of L. acidophilus PTCC 1643 on cultured intestinal epithelial cells infected with Se sE. HT29 cells were cultured in Roswell Park Memorial Institute medium supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin. The cells were treated with L. acidophilus PTCC 1643 after or before challenge with Se sE. At 2 and 4 hours post-infection, we measured changes in the expression levels of TLR2 and TLR4 via real-time polymerase chain reaction. Treatment with L. acidophilus inhibited Se sE-induced increases in TLR2 and TLR4 expression in the infected HT29 cells. Moreover, the expression of TLR2 and TLR4 in cells that were pretreated with L. acidophilus and then infected with Se sE was significantly higher than that in cells infected with Se sE without pretreatment. Taken together, the results indicated that L. acidophilus had an anti-inflammatory effect and modulated the innate immune response to Se sE by influencing TLR2 and TLR4 expression. Our findings suggested that L. acidophilus PTCC 1643 was able to suppress inflammation caused by Se sE infection in HT29 cells and reduce TLR2 and TLR4 expression. Additional in vivo and in vitro studies are required to further elucidate the mechanisms underlying this anti-inflammatory effect.

Selenium hyperaccumulators facilitate selenium-tolerant neighbors via phytoenrichment and reduced herbivory.

PubMed

El Mehdawi, Ali F; Quinn, Colin F; Pilon-Smits, Elizabeth A H

2011-09-13

Soil surrounding selenium (Se) hyperaccumulator plants was shown earlier to be enriched in Se, impairing the growth of Se-sensitive plant species. Because Se levels in neighbors of hyperaccumulators were higher and Se has been shown to protect plants from herbivory, we investigate here the potential facilitating effect of Se hyperaccumulators on Se-tolerant neighboring species in the field. We measured growth and herbivory of Artemisia ludoviciana and Symphyotrichum ericoides as a function of their Se concentration and proximity to hyperaccumulators Astragalus bisulcatus and Stanleya pinnata. When growing next to hyperaccumulators, A. ludoviciana and S. ericoides contained 10- to 20-fold higher Se levels (800-2,000 mg kg(-1) DW) than when growing next to nonaccumulators. The roots of both species were predominantly (70%-90%) directed toward hyperaccumulator neighbors, not toward other neighbors. Moreover, neighbors of hyperaccumulators were 2-fold bigger, showed 2-fold less herbivory damage, and harbored 3- to 4-fold fewer arthropods. When used in laboratory choice and nonchoice grasshopper herbivory experiments, Se-rich neighbors of hyperaccumulators experienced less herbivory and caused higher grasshopper Se accumulation (10-fold) and mortality (4-fold). Enhanced soil Se levels around hyperaccumulators can facilitate growth of Se-tolerant plant species through reduced herbivory and enhanced growth. This study is the first to show facilitation via enrichment with a nonessential element. It is interesting that Se enrichment of hyperaccumulator neighbors may affect competition in two ways, by reducing growth of Se-sensitive neighbors while facilitating Se-tolerant neighbors. Via these competitive and facilitating effects, Se hyperaccumulators may affect plant community composition and, consequently, higher trophic levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Teeth as biomonitors of selenium concentrations in tissues of beluga whales (Delphinapterus leucas).

PubMed

Kinghorn, April; Humphries, Murray M; Outridge, Peter; Chan, Hing Man

2008-08-25

Selenium (Se) is an essential element which has been shown to play an important role in protecting marine mammals against the toxic effects of mercury (Hg) and other metals. It has been suggested that metal concentration in marine mammal teeth can potentially be used as bioindicators for body burden. The objective of this study was to investigate the relationship between Se concentrations in beluga (Delphinapterus leucas) teeth and those previously measured in soft tissues (liver, kidney, muscle and muktuk). Tooth Hg concentrations are also measured, and the relationships between Se and Hg in teeth and soft tissues are examined. Se in the teeth of beluga was measured using hydride generation atomic fluorescence spectrometry (HG-AFS) and Hg in beluga teeth was measured by cold-vapour atomic absorption. Tooth Se concentrations ranged from 108 ng/g to 245 ng/g dry weight, and tooth Hg concentrations ranged from 10 to 189 ng/g dry weight. In the soft tissues, Se concentrations were highest in the liver, followed by kidney, muktuk, and muscle. There were significant correlations between tooth Se concentrations and animal age, tooth Se and liver and muscle Se, and between liver Se and animal age. The molar ratio of Hg:Se in the liver was found to be 0.70. This study is the first to measure Se in the teeth of a marine mammal species, and HG-AFS is found to be an effective technique for determining Se in beluga teeth. Tooth Se can be used as predictor for liver and muscle Se, although these relationships may be strongly influenced by the association of Se with Hg in marine mammal tissues. This study contributes to an increased understanding of the storage and metabolism of Se in marine mammals.

Microbial oxidation and solubilization of precipitated elemental selenium in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Losi, M.E.; Frankenberger, W.T. Jr.

1998-07-01

Oxidation of elemental selenium (Se{sup 0}) leads to increased solubilization and enhanced bioavailability. In this work, laboratory microcosm experiments were conducted to study oxidation of Se{sup 0} in soil and liquid cultures. Major objectives were to examine the oxidation rates of four San Joaquin Valley, California soils, and to assess the contribution of biological vs. chemical processes. For these experiments, red, crystalline Se{sup 0} was prepared by both chemical and biological synthesis, and its presence was confirmed by synchrotron-based x-ray absorption spectroscopy. The amount of Se{sup 0} oxidized over 125 d was from 1 to 10% of Se{sup 0} inmore » soils spiked to 250 mg Se{sup 0} kg{sup {minus}1} and approximately half that in soils spiked to 100 mg Se{sup 0} kg{sup {minus}1}. First order rate constants for oxidation of Se{sup 0} were from 0.05 to 0.32 yr{sup {minus}1} and 0.04 to 0.39 yr{sup {minus}1} at 250 and 100 mg Se{sup 0} kg{sup {minus}1} soil, respectively. The amount of Se{sup 0} oxidized was generally correlated with prior exposure of the soil to Se. Products included either selenite (SeO{sub 3}{sup 2{minus}}), or both (SeO{sub 3}{sup 2{minus}}) and selenate (SeO{sub 4}{sup 2{minus}}). Biotic processes were shown to be of major importance. Both heterotrophic and autotrophic oxidation were observed, and an inorganic C source (NaHCO{sub 3}) was favored relative to glucose. This study demonstrates that Se{sup 0} oxidation in soils is largely biotic in nature, occurs at relatively slow rates and yields both SeO{sub 3}{sup 2{minus}} and SeO{sub 4}{sup 2{minus}}.« less

Distribution of selenium in soils of agricultural fields, western San Joaquin Valley, California

USGS Publications Warehouse

Fujii, Roger; Deverel, S.J.; Hatfield, D.B.

1987-01-01

Soils from three agricultural fields in the western San Joaquin Valley were analyzed for soluble, adsorbed, and total concentrations of selenium (Se) to assess the distribution and forms of Se, and the relation of the distribution and forms of Se to the leaching of Se from soils. Soil samples were collected in three fields with drainage systems of different ages (6, 15, 1.5 yr) and different Se concentrations in drain water (58, 430, 3700 micrograms/L respectively). Preliminary methods to determine total Se and estimate adsorbed Se were developed. Of the three fields, concentrations of soluble Se and salinity were highest in soils from the field drained for 1.5 yr and lowest in the field drained for 6 yr. The field drained for 1.5 yr also had the highest concentration of total Se in soil; a median of 1.2 microgram/gm. Of the total concentration of Se in soil from all three fields, the proportion of adsorbed Se and soluble Se ranged from 1 to 11% and < 1 to 63%, respectively. Most of the variance in soluble Se is explained by salinity ( r sq > 0.68) in saturation extracts of soils sampled from below the water table, reflecting evaporative concentration of Se and salinity. In contrast, most soluble salts and Se apparently have been leached from the unsaturated soils in the fields drained for 6 and 15 yr; therefore, the correlation was lower between Se and salinity in saturation extracts of those soils (r sq < 0.33). Among soils from all three fields, the ratio of Se to salinity in saturation extracts increased with increasing salinity. (Author 's abstract)

Cancer chemoprevention research with selenium in the post-SELECT era: Promises and challenges

PubMed Central

Lü, Junxuan; Zhang, Jinhui; Jiang, Cheng; Deng, Yibin; Özten, Nur; Bosland, Maarten C.

2016-01-01

The negative efficacy outcomes of double-blinded, randomized, placebo-controlled Phase III human clinical trials with selenomethionine (SeMet) and SeMet-rich selenized-yeast (Se-yeast) for prostate cancer prevention and Se-yeast for prevention of non-small cell lung cancer (NSCLC) in North America lead to rejection of SeMet/Se-yeast for cancer prevention in Se-adequate populations. We identify two major lessons from the outcomes of these trials: 1) The antioxidant hypothesis was tested in wrong subjects or patient populations. 2) The selection of Se agents was not supported by cell culture and preclinical animal efficacy data as is common in drug development. We propose that next-generation forms of Se (next-gen Se), such as methylselenol precursors, offer biologically appropriate approaches for cancer chemoprevention but these are faced with formidable challenges. Solid mechanism-based preclinical efficacy assessments and comprehensive safety studies with next-gen Se will be essential to re-vitalize the idea of cancer chemoprevention with Se in the post-SELECT era. We advocate smaller mechanism-driven Phase I/II trials with these next-gen Se to guide and justify future decisions for definitive Phase III chemoprevention efficacy trials. PMID:26595411

Cancer chemoprevention research with selenium in the post-SELECT era: Promises and challenges.

PubMed

Lü, Junxuan; Zhang, Jinhui; Jiang, Cheng; Deng, Yibin; Özten, Nur; Bosland, Maarten C

2016-01-01

The negative efficacy outcomes of double-blinded, randomized, placebo-controlled Phase III human clinical trials with selenomethionine (SeMet) and SeMet-rich selenized-yeast (Se-yeast) for prostate cancer prevention and Se-yeast for prevention of nonsmall cell lung cancer (NSCLC) in North America lead to rejection of SeMet/Se-yeast for cancer prevention in Se-adequate populations. We identify 2 major lessons from the outcomes of these trials: 1) the antioxidant hypothesis was tested in wrong subjects or patient populations, and 2) the selection of Se agents was not supported by cell culture and preclinical animal efficacy data as is common in drug development. We propose that next-generation forms of Se (next-gen Se), such as methylselenol precursors, offer biologically appropriate approaches for cancer chemoprevention but these are faced with formidable challenges. Solid mechanism-based preclinical efficacy assessments and comprehensive safety studies with next-gen Se will be essential to revitalize the idea of cancer chemoprevention with Se in the post-SELECT era. We advocate smaller mechanism-driven Phase I/II trials with these next-gen Se to guide and justify future decisions for definitive Phase III chemoprevention efficacy trials.

Distribution and speciation of ambient selenium in contrasted soils, from mineral to organic rich.

PubMed

Tolu, Julie; Thiry, Yves; Bueno, Maïté; Jolivet, Claudy; Potin-Gautier, Martine; Le Hécho, Isabelle

2014-05-01

Selenium adsorption onto oxy-hydroxides mainly controls its mobility in volcanic soils, red earths and soils poor in organic matter (OM) while the influence of OM was emphasized in podzol and peat soils. This work aims at deciphering how those solid phases influence ambient Se mobility and speciation under less contrasted conditions in 26 soils spanning extensive ranges of OM (1-32%), Fe/Al oxy-hydroxides (0.3-6.1%) contents and pH (4.0-8.3). The soil collection included agriculture, meadow and forest soils to assess the influence of OM quality as well. Trace concentrations of six ambient Se species (Se(IV), Se(VI) and 4 organo-Se compounds) were analyzed by HPLC-ICP-MS in three extractants (ultrapure water, phosphate and sodium hydroxide) targeting Se associated to different soil phases. The Kd values determined from ultrapure water extraction were higher than those reported in commonly used short-term experiments after Se-spiking. Correlations of ambient Se content and distribution with soil parameters explained this difference by an involvement of slow processes in Se retention in soils. The 26 Kd values determined here for a wide variety of soils thus represent a relevant database for long-term prediction of Se mobility. For soils containing less than 20% OM, ambient Se solubility is primarily controlled by its adsorption onto crystalline oxy-hydroxides. However, OM plays an important role in Se mobility by forming organo-mineral associations that may protect adsorbed Se from leaching and/or create anoxic zones (aggregates) where Se is immobilized after its reduction. Although for the first time, inorganic Se(IV), Se(VI) and organo-Se compounds were simultaneously investigated in a large soil collection, high Se proportions remain unidentified in each soil extract, most probably due to Se incorporation and/or binding to colloidal-sized OM. Variations of environmental factors regulating the extent of OM-mineral associations/aggregation may thus lead to changes in Se mobility and bio-availability. Copyright © 2014 Elsevier B.V. All rights reserved.

[Preventive effects of 4 Se-enriched plants on rat stomach cancer induced by MNNG--1. inhibitary effects of different selenium resources on rat aneuploid cell incidence in mucosal epithelium of gastric antrum].

PubMed

Yang, Wenjie; Li, Weidong; Chen, Jing; Chen, Xiaobin

2007-09-01

To obtain new Se resources with high healthy value (both high activity and low toxicity), the preventive efficacies of three Se-enriched higher plants on stomach cancer were compared with selenite and Se-enriched garlic. Ninety weanling male Wistar rats were fed the basal diet for a week, divided equally into nine groups, control, MNNG,Se 75 and 150 microg/kg bw of selenite, Se 150 and 300 microg/kg bw of Se-enriched garlic, Se 150 microg/kg bw of Se-enriched broccoli, Se 300 microg/kg bw of Se-enriched red kales and green kales group. Rats in MNNG and Se supplementation groups were daily given 15 mg/kg bw of MNNG (solved in 1 ml distilled water) and the rats of control group were given 1 ml distilled water by gavage for ten days. Meanwhile, the rats of the control and MNNG group were daily given 1 ml distilled water and the rats of other groups were given 1 ml water suspension of Se-enriched garlic, red kavas, green kavas, broccoli or 1 ml solution of sodium selenite by gavage for seventeen weeks. All rats were freely fed the basal diet and water during the period of the experiment. At the end of 18th week, the rats were sacrificed, the incidence of aneuploid cells (IAC) in mucosal epithelium of the gastric antrum was detected, and the IAC data were analyzed by SPSS 12.0. The results showed that the IACs were 25% and 30%, respectively, in the Se 150 microg/kg bw of Se-enriched garlic and -broccoli group, and were in turn 22%, 50% and 30% in the 300 microg/kg bw of Se-enriched garlic, -red kale and -green kale. No significant differences of IACs were found in the same level of Se supplementation groups by Se-enriched plants. The data showed that Se-enriched broccoli, red kale and green kale had high activities similar to Se-enriched garlic in stomach cancer prevention and lower toxicity than selenite.

Formation of highly luminescent Zn1-xCdxSe nanocrystals using CdSe and ZnSe seeds

NASA Astrophysics Data System (ADS)

Zhang, Ruili; Yang, Ping

2013-05-01

High-quality colloidal Zn1-xCdxSe nanocrystals (NCs) with tunable photoluminescence (PL) from blue to orange were synthesized using oleic acid as a capping agent. The Zn1-xCdxSe NCs were prepared through two approaches: using CdSe or ZnSe seeds. In the case of CdSe NCs as seeds, Zn1-xCdxSe NCs were fabricated by the reaction of Zn, Cd, and Se precursors in the coordinating solvent system at high temperature. The Zn1-xCdxSe NCs revealed orange emitting. A significant blue-shift of absorption and PL spectra were observed with time, indicating the formation of ternary NCs. In contrast, Zn1-xCdxSe NCs revealed blue to green PL for ZnSe NCs as seeds. This is ascribed to an embryonic nuclei-induced alloying process. With increasing time, the Zn1-xCdxSe NCs exhibited a red-shift both in their absorption and PL spectra. This is attributed to the engineering in band gap energy via the control of NC composition. The PL properties of as-prepared alloyed NCs are comparable or even better than those for the parent binary systems. The PL peak wavelength of the Zn1-xCdxSe NCs depended strongly on reaction time and the molar ratio of Cd/Zn. The Zn1-xCdxSe NCs revealed a spherical morphology and exhibited a wurtzite structure according to transmission electron microscopy observation and an X-ray diffraction analysis.

Primary care for diabetes mellitus patients from the perspective of the care model for chronic conditions.

PubMed

Salci, Maria Aparecida; Meirelles, Betina Hörner Schlindwein; Silva, Denise Maria Guerreiro Vieira da

2017-03-09

to assess the health care Primary Health Care professionals provide to diabetes mellitus patients from the perspective of the Modelo de Atenção às Condições Crônicas. qualitative study, using the theoretical framework of Complex Thinking and the Modelo de Atenção às Condições Crônicas and the methodological framework of assessment research. To collect the data, 38 interviews were held with health professionals and managers; observation of the activities by the health teams; and analysis of 25 files of people who received this care. The data analysis was supported by the software ATLAS.ti, using the directed content analysis technique. at the micro level, care was distant from the integrality of the actions needed to assist people with chronic conditions and was centered on the biomedical model. At the meso level, there was disarticulation among the professionals of the Family Health Strategy, between them and the users, family and community. At the macro level, there was a lack of guiding strategies to implement public policies for diabetes in care practice. the implementation of the Modelo de Atenção às Condições Crônicas represents a great challenge, mainly needing professionals and managers who are prepared to work with chronic conditions are who are open to break with the traditional model. evaluar la atención de salud desarrollada por los integrantes de la Atención Primaria de Salud a las personas con diabetes mellitus en la perspectiva del Modelo de Atenção às Condições Crônicas. estudio cualitativo, con referencial teórico del Pensamiento Complejo y del Modelo de Atenção às Condições Crônicas y metodológico de la investigación evaluativa. Para recolectar los datos fueron efectuadas 38 entrevistas con profesionales de salud y gestores; observación de las actividades practicadas por los equipos de salud: y análisis de 25 archivos de personas que recibían esa atención. Los datos fueron analizados con auxilio del software ATLAS.ti, utilizando la técnica de análisis de contenido dirigida. en el ámbito micro, la atención estaba distante de la integralidad de las acciones necesarias para asistir a las personas con enfermedad crónica y estaba centrada en el modelo biomédico. En el ámbito meso, existía desarticulación entre los profesionales de la Estrategia Salud de la Familia, entre estos y los usuarios, familia y comunidad. En el ámbito macro, se identificó ausencia de estrategias directivas para la implementación de las políticas públicas para la diabetes en la práctica asistencial. la implementación del Modelo de Atención a las Condiciones Crónicas representa un gran reto, necesitando principalmente de profesionales y gestores preparados para trabajar con enfermedades crónicas y abiertos a romper con el modelo tradicional. avaliar a atenção à saúde desenvolvida pelos integrantes da Atenção Primária à Saúde às pessoas com diabetes mellitus na perspectiva do Modelo de Atenção às Condições Crônicas. estudo qualitativo, com referencial teórico do Pensamento Complexo e do Modelo de Atenção às Condições Crônicas e metodológico da pesquisa avaliativa. Para a coleta de dados foram realizadas 38 entrevistas com profissionais de saúde e gestores; observação das atividades realizadas pelas equipes de saúde; e análise de 25 prontuários de pessoas que recebiam esse atendimento. A análise de dados teve auxílio do software ATLAS.ti, utilizando a técnica de análise de conteúdo dirigida. no âmbito micro, a assistência estava distante da integralidade das ações necessárias para assistir às pessoas com doença crônica e estava centrada no modelo biomédico. No âmbito meso, existia desarticulação entre os profissionais da Estratégia Saúde da Família, destes com os usuários, família e comunidade. No âmbito macro, identificou-se ausência de estratégias diretivas para a implementação das políticas públicas para o diabetes na prática assistencial. a implementação do Modelo de Atenção às Condições Crônicas constitui um grande desafio, necessitando, principalmente, de profissionais e gestores preparados para trabalharem com doenças crônicas e abertos a romperem com o modelo tradicional.

Procedures for measuring and verifying gastric tube placement in newborns: an integrative review.

PubMed

Dias, Flávia de Souza Barbosa; Emidio, Suellen Cristina Dias; Lopes, Maria Helena Baena de Moraes; Shimo, Antonieta Keiko Kakuda; Beck, Ana Raquel Medeiros; Carmona, Elenice Valentim

2017-07-10

to investigate evidence in the literature on procedures for measuring gastric tube insertion in newborns and verifying its placement, using alternative procedures to radiological examination. an integrative review of the literature carried out in the Cochrane, LILACS, CINAHL, EMBASE, MEDLINE and Scopus databases using the descriptors "Intubation, gastrointestinal" and "newborns" in original articles. seventeen publications were included and categorized as "measuring method" or "technique for verifying placement". Regarding measuring methods, the measurements of two morphological distances and the application of two formulas, one based on weight and another based on height, were found. Regarding the techniques for assessing placement, the following were found: electromagnetic tracing, diaphragm electrical activity, CO2 detection, indigo carmine solution, epigastrium auscultation, gastric secretion aspiration, color inspection, and evaluation of pH, enzymes and bilirubin. the measuring method using nose to earlobe to a point midway between the xiphoid process and the umbilicus measurement presents the best evidence. Equations based on weight and height need to be experimentally tested. The return of secretion into the tube aspiration, color assessment and secretion pH are reliable indicators to identify gastric tube placement, and are the currently indicated techniques. investigar, na literatura, evidências sobre procedimentos de mensuração da sonda gástrica em recém-nascidos e de verificação do seu posicionamento, procedimentos alternativos ao exame radiológico. revisão integrativa da literatura nas bases Biblioteca Cochrane, LILACS, CINAHL, EMBASE, MEDLINE e Scopus, utilizando os descritores "intubação gastrointestinal" e "recém-nascido" em artigos originais. dezessete publicações foram incluídas e categorizadas em "método de mensuração" ou "técnica de verificação do posicionamento". Como métodos de mensuração, foram encontrados os de tomada de duas distâncias morfológicas e os de aplicação de duas fórmulas, uma baseada no peso e outra na altura. Para técnicas de verificação do posicionamento, encontrou-se traçado eletromagnético, atividade elétrica do diafragma, detecção de CO2, solução de índigo carmim, ausculta do epigástrio, aspiração de secreção gástrica, inspeção da cor, avaliação de pH, enzimas e bilirrubina. o método de mensuração que utiliza as medidas do nariz ao lóbulo da orelha ao ponto médio entre apêndice xifoide e cicatriz umbilical apresenta melhores evidências. As equações baseadas em peso e altura necessitam ser testadas experimentalmente. O retorno de secreção na aspiração da sonda, avaliação da cor e do pH da secreção são indicadores confiáveis na identificação do posicionamento da sonda gástrica, e são as técnicas atualmente indicadas. investigar, en la literatura, evidencias sobre procedimientos de medición de la sonda gástrica en recién nacidos y de verificación de su posicionamiento, procedimientos alternativos al examen radiológico. revisión integradora de la literatura en las bases Biblioteca Cochrane, LILACS, CINAHL, EMBASE, MEDLINE y Scopus, utilizando los descriptores "intubación gastrointestinal" y "recién nacido" en artículos originales. diecisiete publicaciones fueron incluidas y categorizadas en "método de medición" o "técnica de verificación del posicionamiento". Como métodos de medición, fueron encontrados los de medida de dos distancias morfológicas y los de aplicación de dos fórmulas (una basada en el peso y otra en la altura). Para las técnicas de verificación del posicionamiento, se encontró: trazado electromagnético, actividad eléctrica del diafragma, detección de CO2, solución de índigo carmín, auscultación del epigastrio, aspiración de secreción gástrica, inspección del color, evaluación de pH, enzimas y bilirrubina. el método de medición que utiliza las medidas de la nariz al lóbulo de la oreja al punto medio entre apéndice xifoideo y cicatriz umbilical, presenta las mejores evidencias. Las ecuaciones basadas en peso y altura necesitan ser comprobadas experimentalmente. El retorno de secreción en la aspiración de la sonda, evaluación del color y del pH de la secreción son indicadores confiables en la identificación del posicionamiento de la sonda gástrica, y son las técnicas actualmente indicadas.

Applicability and methodology of determining sustainable yield in groundwater systems

NASA Astrophysics Data System (ADS)

Kalf, Frans R. P.; Woolley, Donald R.

2005-03-01

There is currently a need for a review of the definition and methodology of determining sustainable yield. The reasons are: (1) current definitions and concepts are ambiguous and non-physically based so cannot be used for quantitative application, (2) there is a need to eliminate varying interpretations and misinterpretations and provide a sound basis for application, (3) the notion that all groundwater systems either are or can be made to be sustainable is invalid, (4) often there are an excessive number of factors bound up in the definition that are not easily quantifiable, (5) there is often confusion between production facility optimal yield and basin sustainable yield, (6) in many semi-arid and arid environments groundwater systems cannot be sensibly developed using a sustained yield policy particularly where ecological constraints are applied. Derivation of sustainable yield using conservation of mass principles leads to expressions for basin sustainable, partial (non-sustainable) mining and total (non-sustainable) mining yields that can be readily determined using numerical modelling methods and selected on the basis of applied constraints. For some cases there has to be recognition that the groundwater resource is not renewable and its use cannot therefore be sustainable. In these cases, its destiny should be the best equitable use.

Selenium-induced toxicity is counteracted by sulfur in broccoli (Brassica oleracea L. var. italic)

USDA-ARS?s Scientific Manuscript database

Selenium (Se) is an essential micronutrient for humans. Increasing Se content in food crops offers an effective approach to enhance the consumption of Se in human diets. A thoroughly understanding of the effects of Se on plant growth is important for Se biofortification in food crops. Given that Se ...

Assessing the anticancer compounds Se-methylselenocysteine and glucosinolates in Se-biofortified broccoli (brassica oleracea L. var. italica) sprouts and florets

USDA-ARS?s Scientific Manuscript database

Broccoli (Brassica oleracea L. var. italica) is a rich source of chemopreventive compounds. Here, we evaluated and compared the effect of selenium (Se) treatment on the accumulation of anticancer compound Se-methylselenocysteine (SeMSCys) and glucosinolates in broccoli sprouts and florets. Total Se ...

Biogenic selenium nanoparticles: current status and future prospects.

PubMed

Wadhwani, Sweety A; Shedbalkar, Utkarsha U; Singh, Richa; Chopade, Balu A

2016-03-01

Selenium nanoparticles (SeNPs) are gaining importance in the field of medicine owing to their antibacterial and anticancer properties. SeNPs are biocompatible and non-toxic compared to the counterparts, selenite (SeO3 (-2)) and selenate (SeO4 (-2)). They can be synthesized by physical, chemical, and biological methods and have distinct bright orange-red color. Biogenic SeNPs are stable and do not aggregate owing to natural coating of the biomolecules. Various hypotheses have been proposed to describe the mechanism of microbial synthesis of SeNPs. It is primarily a two-step reduction process from SeO4 (-2) to SeO3 (-2) to insoluble elemental selenium (Se(0)) catalyzed by selenate and selenite reductases. Phenazine-1-carboxylic acid and glutathione are involved in selenite reduction. Se factor A (SefA) and metalloid reductase Rar A present on the surface of SeNPs confer stability to the nanoparticles. SeNPs act as potent chemopreventive and chemotherapeutic agents. Conjugation with antibiotics enhances their anticancer efficacy. These also have applications in nanobiosensors and environmental remediation.

Enhancing Thermoelectric Performance of PbSe by Se Vacancies

NASA Astrophysics Data System (ADS)

Liu, Yefeng; You, Li; Wang, Chenyang; Zhang, Jiye; Yang, Jiong; Guo, Kai; Luo, Jun; Zhang, Wenqing

2018-02-01

Self-doped n-type PbSe1-δ thermoelectric compounds have been successfully synthesized by the melting and annealing method. The Se vacancies are created by intentionally produced deficiency of Se elements during the sample preparation. Such intrinsic doping can raise the electron concentration to a value as high as 1.2 × 1019 cm-3, leading to greatly improved electrical conductivity and power factor in the n-type PbSe1-δ . Furthermore, the presence of Se vacancies effectively enhances the phonon scattering, resulting in reduced lattice thermal conductivity. Thus, the thermoelectric performance of n-type PbSe1-δ is significantly improved by the formation of intrinsic Se vacancies. The achieved ZT value for the Se-vacancy-rich sample varies from ˜ 0.4 at 330 K to ˜ 1.0 at 675 K, which is comparable to those of the reported n-type PbSe materials with extrinsic doping. In addition, the average ZT of our n-type PbSe system reaches 0.77, which approaches the value of p-type PbTe.

Surface Passivation of CdSe Quantum Dots in All Inorganic Amorphous Solid by Forming Cd1-xZnxSe Shell.

PubMed

Xia, Mengling; Liu, Chao; Zhao, Zhiyong; Wang, Jing; Lin, Changgui; Xu, Yinsheng; Heo, Jong; Dai, Shixun; Han, Jianjun; Zhao, Xiujian

2017-02-07

CdSe quantum dots (QDs) doped glasses have been widely investigated for optical filters, LED color converter and other optical emitters. Unlike CdSe QDs in solution, it is difficult to passivate the surface defects of CdSe QDs in glass matrix, which strongly suppress its intrinsic emission. In this study, surface passivation of CdSe quantum dots (QDs) by Cd 1-x Zn x Se shell in silicate glass was reported. An increase in the Se/Cd ratio can lead to the partial passivation of the surface states and appearance of the intrinsic emission of CdSe QDs. Optimizing the heat-treatment condition promotes the incorporation of Zn into CdSe QDs and results in the quenching of the defect emission. Formation of CdSe/Cd 1-x Zn x Se core/graded shell QDs is evidenced by the experimental results of TEM and Raman spectroscopy. Realization of the surface passivation and intrinsic emission of II-VI QDs may facilitate the wide applications of QDs doped all inorganic amorphous materials.

Tuning the emission of aqueous Cu:ZnSe quantum dots to yellow light window

NASA Astrophysics Data System (ADS)

Wang, Chunlei; Hu, Zhiyang; Xu, Shuhong; Wang, Yanbin; Zhao, Zengxia; Wang, Zhuyuan; Cui, Yiping

2015-07-01

Synthesis of internally doped Cu:ZnSe QDs in an aqueous solution still suffers from narrow tunable emissions from the blue to green light window. In this work, we extended the emission window of aqueous Cu:ZnSe QDs to the yellow light window. Our results show that high solution pH, multiple injections of Zn precursors, and nucleation doping strategy are three key factors for preparing yellow emitted Cu:ZnSe QDs. All these factors can depress the reactivity of CuSe nuclei and Zn monomers, promoting ZnSe growth outside CuSe nuclei rather than form ZnSe nuclei separately. With increased ZnSe QD size, the conduction band and nearby trap state energy levels shift to higher energy sites, causing Cu:ZnSe QDs to have a much longer emission.

Selenium Preferentially Accumulates in the Eye Lens Following Embryonic Exposure: A Confocal X-ray Fluorescence Imaging Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Sanjukta; Thomas, Jith; Sylvain, Nicole J.

Maternal transfer of elevated selenium (Se) to offspring is an important route of Se exposure for fish in the natural environment. However, there is a lack of information on the tissue specific spatial distribution and speciation of Se in the early developmental stages of fish, which provide important information about Se toxicokinetics. The effect of maternal transfer of Se was studied by feeding adult zebrafish a Se-elevated or a control diet followed by collection of larvae from both groups. Novel confocal synchrotron-based techniques were used to investigate Se within intact preserved larvae. Confocal X-ray fluorescence imaging was used to comparemore » Se distributions within specific planes of an intact larva from each of the two groups. The elevated Se treatment showed substantially higher Se levels than the control; Se preferentially accumulated to highest levels in the eye lens, with lower levels in the retina, yolk and other tissues. Confocal X-ray absorption spectroscopy was used to determine that the speciation of Se within the eye lens of the intact larva was a selenomethionine-like species. Preferential accumulation of Se in the eye lens may suggest a direct cause-and-effect relationship between exposure to elevated Se and Se-induced ocular impairments reported previously. This study illustrates the effectiveness of confocal X-ray fluorescence methods for investigating trace element distribution and speciation in intact biological specimens« less

Lentic, lotic, and sulfate-dependent waterborne selenium screening guidelines for freshwater systems.

PubMed

DeForest, David K; Brix, Kevin V; Elphick, James R; Rickwood, Carrie J; deBruyn, Adrian M H; Tear, Lucinda M; Gilron, Guy; Hughes, Sarah A; Adams, William J

2017-09-01

There is consensus that fish are the most sensitive aquatic organisms to selenium (Se) and that Se concentrations in fish tissue are the most reliable indicators of potential toxicity. Differences in Se speciation, biological productivity, Se concentration, and parameters that affect Se bioavailability (e.g., sulfate) may influence the relationship between Se concentrations in water and fish tissue. It is desirable to identify environmentally protective waterborne Se guidelines that, if not exceeded, reduce the need to directly measure Se concentrations in fish tissue. Three factors that should currently be considered in developing waterborne Se screening guidelines are 1) differences between lotic and lentic sites, 2) the influence of exposure concentration on Se partitioning among compartments, and 3) the influence of sulfate on selenate bioavailability. Colocated data sets of Se concentrations in 1) water and particulates, 2) particulates and invertebrates, and 3) invertebrates and fish tissue were compiled; and a quantile regression approach was used to derive waterborne Se screening guidelines. Use of a regression-based approach for describing relationships in Se concentrations between compartments reduces uncertainty associated with selection of partitioning factors that are generally not constant over ranges of exposure concentrations. Waterborne Se screening guidelines of 6.5 and 3.0 μg/L for lotic and lentic water bodies were derived, and a sulfate-based waterborne Se guideline equation for selenate-dominated lotic waters was also developed. Environ Toxicol Chem 2017;36:2503-2513. © 2017 SETAC. © 2017 SETAC.

Bacterial reduction of selenium in coal mine tailings pond sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siddique, T.; Arocena, J.M.; Thring, R.W.

2007-05-15

Sediment from a storage facility for coal tailings solids was assessed for its capacity to reduce selenium (Se) by native bacterial community. One Se{sup 6+}-reducing bacterium Enterobacter hormaechei (Tar11) and four Se{sup 4+}-reducing bacteria, Klebsiella pneumoniae (Tar1), Pseudomonasfluorescens (Tar3), Stenotrophomonas maltophilia (Tar6), and Enterobacter amnigenus (Tar8) were isolated from the sediment. Enterobacter horinaechei removed 96% of the added Se{sup 6+} (0.92 mg L{sup -1} from the effluents when Se6+ was determined after 5 d of incubation. Analysis of the red precipitates showed that Se{sup 6+} reduction resulted in the formation of spherical particles ({lt}1.0 {mu} m) of Se 0 asmore » observed under scanning electron microscope (SEM) and confirmed by EDAX. Selenium speciation was performed to examine the fate of the added Se{sup 6+} in the sediment with or without addition of Enterobacter hormaechei cells. More than 99% of the added Se{sup 6+} (about 2.5 mg L{sup -1}) was transformed in the nonsterilized sediment (without Enterobacter hormaechei cells) as well as in the sterilized (heat-killed) sediment (with Enterobacter hormaechei cells). The results of this study suggest that the lagoon sediments at the mine site harbor Se{sup 6+}- and Se{sup 4+} -reducing bacteria and may be important sinks for soluble Se (Se{sup 6+} and Se{sup 4+}). Enterobacter hormaechei isolated from metal-contaminated sediment may have potential application in removing Se from industrial effluents.« less

Selenium stable isotope investigation into selenium biogeochemical cycling in a lacustrine environment: Sweitzer Lake, Colorado.

PubMed

Clark, Scott K; Johnson, Thomas M

2010-01-01

We present a comprehensive set of Se concentration and isotope ratio data collected over a 3-yr period from dissolved, sediment-hosted, and organically bound Se in a Se-contaminated lake and littoral wetland. Median isotope ratios of these various pools of Se spanned a narrow isotopic range (delta80/76Se(SRM-3149)) = 1.14-2.40 per thousand). Selenium (VI) reduction in the sediments is an important process in this system, but its isotopic impact is muted by the lack of direct contact between surface waters and reduction sites within sediments. This indicates that using Se isotope data as an indicator of microbial or abiotic Se oxyanion reduction is not effective in this or other similar systems. Isotopic data suggest that most Se(IV) in the lake originates from oxidation of organically bound Se rather than directly through Se(VI) reduction. Mobilization of Se(VI) from bedrock involves only a slight isotopic shift. Temporally constant isotopic differences observed in Se(VI) from two catchment areas suggest the potential for tracing Se(VI) from different source areas. Phytoplankton isotope ratios are close to those of the water, with a small depletion in heavy isotopes (0.56 per thousand). Fish tissues nearly match the phytoplankton, being only slightly depleted in the heavier isotopes. This suggests the potential for Se isotopes as migration indicators. Volatile, presumably methylated Se was isotopically very close to median values for phytoplankton and macrophytes, indicating a lack of isotopic fractionation during methylation.

Effects of supplementation of fertilizers on human selenium status in Finland.

PubMed

Aro, A; Alfthan, G; Varo, P

1995-03-01

The Se concentration of foods can be increased by supplementing fertilizers with soluble Se compounds. In Finland the availability of soil Se for plants is poor owing to the relatively low Se concentration, low pH and high iron content of the soil. Since 1984 multimineral fertilizers have been supplemented with Se (16 mg kg-1 to fertilizers for grain production and 6 mg kg-1 to those for fodder production) in the form of sodium selenate. Within two years a three-fold increase of mean Se intake was observed. The supplementation affected the Se content of all major food groups with the exception of fish. The concomitant human serum Se concentration increased by 70%. In 1990 the amount of Se that was supplemented was reduced to 6 mg kg-1 for all fertilizers. This reduced the mean Se intake by 30% and the serum Se concentration decreased by 25% from the highest levels observed in 1989. Plants take up part of the supplemented selenate and transform it into organic Se compounds, mainly selenomethionine. This affects human nutrition by increasing the Se content of foods of both animal and vegetable origin. According to data obtained in Finland, supplementation of fertilizers with Se is a safe and effective means of increasing the Se intake of both animals and humans that is feasible in countries with relatively uniform geochemical conditions. This kind of intervention requires careful monitoring of the effects on both animal and human nutrition and the environment.

[Effects of selenium compounds on proliferation, migration and adhesion of HeLa cells].

PubMed

Sun, Licui; Lu, Jiaxi; Wang, Qin; Liu, Yiqun; Han, Feng; Yang, Yanhua; Zhang, Hongkun; Huang, Zhenwu

2015-03-01

To explore the effects of methylseleninic acid (MeSeA), selenomethionine (SeMet) and methylselenocysteine (MeSeCys) on proliferation, migration and adhesion of HeLa cells. HeLa cells were cultured and treated with MeSeA, SeMet and MeSeCys for 12 - 72 h respectively. MTT assay, healing assay and in vitro cell Matrigel adhesion assay were used to detect the proliferation, migration and adhesion of HeLa cells. Compared to the control group, the proliferation of HeLa cells was remarkably inhibited by MeSeA (P <0. 01). The migration of HeLa cells in MeSeA group was inhibited by 34% (P < 0. 05) and 26% (P < 0. 05) in 4 h and 8 h, respectively. However, the migration of HeLa cells with inhibitions of 18% and 13% was in SeMet group in 4 h and 8 h. The inhibitions of HeLa cell migration in MeSeCys group was 28% (P < 0.05) and 5% in 4 h and 8 h, respectively. In addition, the adhesive function of HeLa cells in the MeSeA group, the SeMet group as well as the MeSeCys group were inhibited by 36% (P < 0. 01), 25% and 49% (P < 0. 01). The proliferation and migration of HeLa cell were effectively inhibited by MeSeA, while the adhesive function of HeLa cell was remarkably inhibited by MeSeCys.

First-principles calculations of nitrogen-doped antimony triselenide: A prospective material for solar cells and infrared optoelectronic devices

NASA Astrophysics Data System (ADS)

Sajid-ur-Rehman; Butt, Faheem K.; Li, Chuanbo; Ul Haq, Bakhtiar; Tariq, Zeeshan; Aleem, F.

2018-06-01

This study is focused on calculation of the electronic structure and optical properties of non-metal doped Sb2Se3 using the first-principles method. One and two N atoms are introduced to Sb and Se sites in a Sb2Se3 crystal. When one and two N atoms are introduced into the Sb2Se3 lattice at Sb sites, the electronic structure shows that the doping significantly modifies the bandgap of Sb2Se3 from 1.11 eV to 0.787 and 0.685 eV, respectively. When N atoms are introduced to Se sites, the material shows a metallic behavior. The static dielectric constants ɛ1(0) for Sb16Se24, Sb15N1Se24, Sb14N2Se24, Sb16Se23N1, and Sb16Se22N2 are 14.84, 15.54, 15.02, 18.9, and 39.29, respectively. The calculated values of the refractive index n(0) for Sb16Se24, Sb15N1Se24, Sb14N2Se24, Sb16Se23N1, and Sb16Se22N2 are 3.83, 3.92, 3.86, 4.33, and 6.21, respectively. The optical absorbance and optical conductivity curves of the crystal for N-doping at Sb sites show a significant redshift towards the short-wave infrared spectral region as compared to N-doping at Se sites. The modulation of the static refractive index and static dielectric constant is mainly dependent on the doping level. The optical properties and bandgap narrowing effect suggest that the N-doped Sb2Se3is a promising new semiconductor and can be a replacement for GaSb due to its very similar bandgap and low cost.

Distinguishing in-hospital and out-of-hospital status epilepticus: clinical implications from a 10-year cohort study.

PubMed

Sutter, R; Semmlack, S; Spiegel, R; Tisljar, K; Rüegg, S; Marsch, S

2017-09-01

The aim was to determine differences of clinical, treatment and outcome characteristics between patients with in-hospital and out-of-hospital status epilepticus (SE). From 2005 to 2014, clinical data were assessed in adults with SE treated in an academic medical care centre. Clinical characteristics, treatment and outcomes were compared between patients with in-hospital and out-of-hospital SE. Amongst 352 patients, 213 were admitted with SE and 139 developed in-hospital SE. Patients with in-hospital SE had more acute/fatal aetiologies (60% vs. 35%, P < 0.001), fewer previous seizures (33% vs. 50%, P = 0.002), a higher median Charlson Comorbidity Index (3 vs. 2, P < 0.001), longer median SE duration (1 vs. 0.5 days, P = 0.001), more refractory SE (52% vs. 39%, P = 0.022), less return to functional baseline (38% vs. 54%, P = 0.006) and increased mortality (29% vs. 19%, P = 0.001). Whilst in multivariable analyses an increasing Status Epilepticus Severity Score (STESS) was an independent predictor for death in both groups, increased Charlson Comorbidity Index and treatment refractory SE were associated with death only in patients with in-hospital SE. Continuous anaesthesia for refractory SE was associated with increased mortality only in patients with out-of-hospital SE. The area under the receiver operating curve was 0.717 for prediction of death by STESS in patients with in-hospital SE and 0.811 in patients with out-of-hospital SE. Patients with in-hospital SE had more fatal aetiologies and comorbidities, refractory SE, less return to functional baseline, and increased mortality compared to patients with out-of-hospital SE. Whilst the STESS was a robust predictor for death in both groups, the association between continuous anaesthesia and death was limited to out-of-hospital SE. © 2017 EAN.

71Ga-77Se connectivities and proximities in gallium selenide crystal and glass probed by solid-state NMR

NASA Astrophysics Data System (ADS)

Nagashima, Hiroki; Trébosc, Julien; Calvez, Laurent; Pourpoint, Frédérique; Mear, François; Lafon, Olivier; Amoureux, Jean-Paul

2017-09-01

We introduce two-dimensional (2D) 71Ga-77Se through-bond and through-space correlation experiments. Such correlations are achieved using (i) the J-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer (J-RINEPT) method with 71Ga excitation and 77Se Carr-Purcell-Meiboon-Gill (CPMG) detection, as well as (ii) the J- or dipolar-mediated Hetero-nuclear Multiple-Quantum Correlation (J- or D-HMQC) schemes with 71Ga excitation and quadrupolar CPMG (QCPMG) detection. These methods are applied to the crystalline β-Ga2Se3 and the 0.2Ga2Se3-0.8GeSe2 glass. Such glass leads to a homogeneous and reproducible glass-ceramic, which is a good alternative to single-crystalline Ge and polycrystalline ZnSe materials for making lenses transparent in the IR range for thermal imaging applications. We show that 2D 71Ga-77Se correlation experiments allow resolving the 77Se signals of molecular units, which are not resolved in the 1D 77Se CPMG spectrum. Additionally, the build-up curves of the J-RINEPT and the J-HMQC experiments allow the estimate of the 71Ga-77Se J-couplings via one and three-bonds in the three-dimensional network of β-Ga2Se3. Furthermore, these build-up curves show that the one-bond 1J71Ga-77Se couplings in the 0.2Ga2Se3-0.8GeSe2 glass are similar to those measured for β-Ga2Se3. We also report 2D 71Ga Satellite Transition Magic-Angle Spinning (STMAS) spectrum of β-Ga2Se3 using QCPMG detection at high magnetic field and high Magic-Angle Spinning frequency using large radio frequency field. Such spectrum allows separating the signal of β-Ga2Se3 and that of an impurity.

Liquid chromatography-mass spectrometry (LC-MS): a powerful combination for selenium speciation in garlic (Allium sativum).

PubMed

Dumont, Emmie; Ogra, Yasumitsu; Vanhaecke, Frank; Suzuki, Kazuo T; Cornelis, Rita

2006-03-01

Liquid chromatography (LC) hyphenated with both elemental and molecular mass spectrometry has been used for Se speciation in Se-enriched garlic. Different species were separated by ion-pair liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) after hot-water extraction. They were identified by on-line reversed-phase liquid chromatography-electrospray ionization tandem mass spectrometry (RPLC-ESI-MS-MS). Se-methionine and Se-methylselenocysteine were determined by monitoring their product ions. Another compound, gamma-glutamyl-Se-methylselenocysteine, shown to be the most abundant form of Se in the garlic, was determined without any additional sample pre-treatment after extraction and without the need for a synthesized standard. Product ions for this dipeptide were detected by LC-ESI-MS-MS for three isotopes of Se-78 Se, 80Se: and 82Se. The method was extended to the species extracted during in-vitro gastrointestinal digestion. Because both Se-methylselenocysteine and gamma-glutamyl-Se-methylselenocysteine have anticarcinogenic properties, their extractability and stability during human digestion are very important. Garlic was also treated with saliva, to enable detection and analysis of species extracted during mastication. Detailed information on the extractability of selenium species by both simulated gastric and intestinal fluid are given, and variation of the distribution of Se among the different species with time is discussed. Although the main species in garlic is the dipeptide gamma-glutamyl-Se-methylselenocysteine, Se-methylselenocysteine is the main compound present in the extracts after treatment with gastrointestinal fluids. Two more, so far unknown compounds were observed in the chromatogram. The extracted species and their transformations were analysed by combining LC-ICP-MS and LC-ESI-MS-MS. In both the simulated gastric and intestinal digests, Se-methionine, Se-methylselenocysteine, and gamma-glutamyl-Se-methylselenocysteine could be determined by LC-ESI-MS-MS by measuring their typical product ions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shiyan; Mei, Dajiang, E-mail: meidajiang718@pku.edu.cn; Du, Xin

Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe{sub 4} has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe{sub 4} is composed of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4}(M=Si, Ga) tetrahedra. AgGaSiSe{sub 4} is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe{sub 4} and the value is 0.33 eV larger than that of Ag{sub 3}Ga{sub 3}SiSe{sub 8} (2.30more » eV). - Graphical abstract: The Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe{sub 4} was synthesized for the first time. AgGaSiSe{sub 4} crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4} (M=Si, Ge) tetrahedra. Display Omitted - Highlights: • Study of Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2). • Successful synthesis of new compound named AgGaSiSe{sub 4}. • AgGaSiSe{sub 4} crystallizes in space group Aea2 and adopts a three-dimensional framework. • The energy band gap of AgGaSiSe{sub 4} is enlarged compared with Ag{sub 3}Ga{sub 3}SiSe{sub 8}.« less

A new generation of alloyed/multimetal chalcogenide nanowires by chemical transformation.

PubMed

Yang, Yuan; Wang, Kai; Liang, Hai-Wei; Liu, Guo-Qiang; Feng, Mei; Xu, Liang; Liu, Jian-Wei; Wang, Jin-Long; Yu, Shu-Hong

2015-11-01

One-dimensional metal chalcogenide nanostructures are important candidates for many technological applications such as photovoltaic and thermoelectric devices. However, the design and synthesis of one-dimensional metal chalcogenide nanostructured materials with controllable components and properties remain a challenge. We report a general chemical transformation process for the synthesis of more than 45 kinds of one-dimensional alloyed/hybrid metal chalcogenide nanostructures inherited from mother template Te x Se y @Se core-shell nanowires with tunable compositions. As many as nine types of monometal chalcogenide alloy nanowires (including AgSeTe, HgSeTe, CuSeTe, BiSeTe, PbSeTe, CdSeTe, SbSeTe, NiSeTe, and CoSeTe) can be synthesized. Alloyed and hybrid nanowires integrated with two or more alloyed metal chalcogenide phases can also be prepared. The compositions of all of these metal chalcogenide nanowires are tunable within a wide range. This protocol provides a new general route for the controllable synthesis of a new generation of one-dimensional metal chalcogenide nanostructures.

Selenium Biofortification in Rice ( Oryza sativa L.) Sprouting: Effects on Se Yield and Nutritional Traits with Focus on Phenolic Acid Profile.

PubMed

D'Amato, Roberto; Fontanella, Maria Chiara; Falcinelli, Beatrice; Beone, Gian Maria; Bravi, Elisabetta; Marconi, Ombretta; Benincasa, Paolo; Businelli, Daniela

2018-04-25

The contents of total Se and of inorganic and organic Se species, as well as the contents of proteins, chlorophylls, carotenoids, and phenolic acids, were measured in 10-day old sprouts of rice ( Oryza sativa L.) obtained with increasing levels (15, 45, 135, and 405 mg Se L -1 ) of sodium selenite and sodium selenate and with distilled water as control. Increasing Se levels increased organic and inorganic Se contents of sprouts, as well as the content of phenolic acids, especially in their soluble conjugated forms. Moderate levels of sodium selenite (i.e., not higher that 45 mg L -1 ) appeared the best compromise to obtain high Se and phenolic acid yields together with high proportion of organic Se while limiting residual Se in the germination substrate waste. Se biofortification of rice sprouts appears a feasible and efficient way to promote Se and phenolic acid intake in human diet, with well-known health benefits.

Selenomethionine as a Safer Substitute for Barium Selenate in Long-Acting Injectable Se Supplements for Food-Producing Animals.

PubMed

Knowles, Scott O; Grace, Neville D

2017-09-20

Nutritional supplementation with selenium (Se) can prevent Se deficiency in food-producing animals. Injection with slow-release formulations is a preferred method for free-range grazing sheep and cattle, and barium selenate (BaSeO 4 ) provides optimal efficacy. This chemical can become a health risk to humans if the concentrated depot of an injection site is consumed, and consequently such use is recently banned in the EU. A possible replacement is selenomethionine (SeMet), a naturally occurring form of Se supplementation hitherto only administered orally. In four animal studies we found that injection with SeMet maintained nutritionally adequate concentrations of Se in blood and tissues of lambs for at least 191 days and in blood and milk of dairy cows for at least 95 days. Stereoisomer forms L- and DL-SeMet were functionally equivalent. This is the first demonstration that injectable SeMet can deliver efficacy similar to BaSeO 4 but with less risk of undesirable residues in edible tissues.

Study of selenocompounds from selenium-enriched culture of edible sprouts.

PubMed

Funes-Collado, Virginia; Morell-Garcia, Albert; Rubio, Roser; López-Sánchez, José Fermín

2013-12-15

Selenium is recognised as an essential micronutrient for humans and animals. One of the main sources of selenocompounds in the human diet is vegetables. Therefore, this study deals with the Se species present in different edible sprouts grown in Se-enriched media. We grew alfalfa, lentil and soy in a hydroponic system amended with soluble salts, containing the same proportion of Se, in the form of Se(VI) and Se(IV). Total Se in the sprouts was determined by acidic digestion in a microwave system and by ICP/MS. Se speciation was carried out by enzymatic extraction (Protease XIV) and measured by LC-ICP/MS. The study shows that the Se content of plants depends on the content in the growth culture, and that part of the inorganic Se was biotransformed mainly into SeMet. These results contribute to our understanding of the uptake of inorganic Se and its biotransformation by edible plants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Li3Ge3Se6: the first ternary lithium germanium selenide with interesting ∞[Ge6Se12]n chains constructed by ethane-like [Ge2Se6]6- clusters.

PubMed

Li, Guangmao; Zhen, Ni; Chu, Yu; Zhou, Zhongxiang

2017-12-21

Li 3 Ge 3 Se 6 , the first compound of the ternary Li/Ge/Se system, has been synthesized. Note that interesting 1D ∞ [Ge 6 Se 12 ] n chains constructed by ethane-like [Ge 2 Se 6 ] 6- clusters were discovered in its structure. Investigations on the structures of all the [Ge 2 Se 6 ] 6- cluster-containing compounds have shown that only in Li 3 Ge 3 Se 6 are there 1D chains composed of [Ge 2 Se 6 ] 6- clusters, which result from the space limitation within the tunnels surrounded by LiSe 6 octahedra. Raman spectrum was obtained to demonstrate the existence of Ge-Ge bonds. UV-visible-NIR diffuse reflection spectrum showed an optical bandgap of 2.08 eV. Theoretical calculations based on first principles have also been performed for its band structure and density of states to analyze its structure-property relationship.

Method of fabricating high-efficiency Cu(In,Ga)(SeS).sub.2 thin films for solar cells

DOEpatents

Noufi, Rommel; Gabor, Andrew M.; Tuttle, John R.; Tennant, Andrew L.; Contreras, Miguel A.; Albin, David S.; Carapella, Jeffrey J.

1995-01-01

A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositing a first layer of (In,Ga).sub.x (Se,S).sub.y followed by depositing just enough Cu+(Se,S) or Cu.sub.x (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga).sub.x (Se,S).sub.y is deposited first, followed by deposition of all the Cu+(Se,S) or Cu.sub.x (Se,S) to go near stoichiometric, possibly or even preferably slightly Cu-rich, and then in turn followed by deposition of the remainder (about 1 to 10%) of the (In,Ga).sub.x (Se,S).sub.y to end with a slightly Cu-poor composition. In yet another variation, a small portion (about 1 to 10%) of the (In,Ga).sub.x (Se,S).sub.y is first deposited as a seed layer, followed by deposition of all of the Cu+(Se,S) or Cu.sub.x (Se,S) to make a very Cu-rich mixture, and then followed deposition of the remainder of the (In,Ga).sub.x (Se,S).sub.y to go slightly Cu-poor in the final Cu(In,Ga)(Se,S).sub.2 thin film.

Method of fabricating high-efficiency Cu(In,Ga)(Se,S){sub 2} thin films for solar cells

DOEpatents

Noufi, R.; Gabor, A.M.; Tuttle, J.R.; Tennant, A.L.; Contreras, M.A.; Albin, D.S.; Carapella, J.J.

1995-08-15

A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S){sub 2} comprises depositing a first layer of (In,Ga){sub x} (Se,S){sub y} followed by depositing just enough Cu+(Se,S) or Cu{sub x} (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga){sub x} (Se,S){sub y} is deposited first, followed by deposition of all the Cu+(Se,S) or Cu{sub x} (Se,S) to go near stoichiometric, possibly or even preferably slightly Cu-rich, and then in turn followed by deposition of the remainder (about 1 to 10%) of the (In,Ga){sub x} (Se,S){sub y} to end with a slightly Cu-poor composition. In yet another variation, a small portion (about 1 to 10%) of the (In,Ga){sub x} (Se,S){sub y} is first deposited as a seed layer, followed by deposition of all of the Cu+(Se,S) or Cu{sub x} (Se,S) to make a very Cu-rich mixture, and then followed deposition of the remainder of the (In,Ga){sub x} (Se,S){sub y} to go slightly Cu-poor in the final Cu(In,Ga)(Se,S){sub 2} thin film. 5 figs.

Construction of a Cordyceps sinensis exopolysaccharide-conjugated selenium nanoparticles and enhancement of their antioxidant activities.

PubMed

Xiao, Yidong; Huang, Qilin; Zheng, Zhaomin; Guan, Han; Liu, Shiyu

2017-06-01

A Cordyceps sinensis exopolysaccharide (EPS)-conjugated selenium nanoparticles (SeNPs) were successfully constructed through the reduction of SeO 3 2- . The EPS-SeNPs were characterized in terms of formation, morphology, size, Se distribution and phase by UV-vis, FT-IR, transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray (EDX) and wide angle X-ray diffraction (WAXD) measurements. Results revealed that the SeNPs conjugated to EPS were amorphous and could be well dispersed at a size range of 80-125nm. The interactions between the OH groups of EPS and SeNPs substituted for intermolecular interaction in native EPS to form new CO⋯Se bonds, resulting in good dispersion of SeNPs in the EPS matrix. Besides, the EPS-SeNPs at different Se/P ratios exhibited significant scavenging ability on superoxide anion radical (O 2 - ) and ABTS radical cation (ABTS + ) when compared to pure EPS, indicating that the conjugated SeNPs reinforced antioxidant effect of EPS. This work not only provides a simple and efficient way to construct well-dispersed SeNPs in aqueous system, and demonstrates the vital role of the EPS as a biopolymer template for dispersion, stabilization and size control of SeNPs, but also finds the EPS-SeNPs can potentially serve as a good antioxidant towards O 2 - and ABTS + . Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanistic understanding of MeHg-Se antagonism in soil-rice systems: the key role of antagonism in soil

PubMed Central

Wang, Yongjie; Dang, Fei; Evans, R. Douglas; Zhong, Huan; Zhao, Jiating; Zhou, Dongmei

2016-01-01

Methylmercury (MeHg) accumulation in rice has great implications for human health. Here, effects of selenium (Se) on MeHg availability to rice are explored by growing rice under soil or foliar fertilization with Se. Results indicate that soil amendment with Se could reduce MeHg levels in soil and grain (maximally 73%). In contrast, foliar fertilization with Se enhanced plant Se levels (3–12 folds) without affecting grain MeHg concentrations. This evidence, along with the distinct distribution of MeHg and Se within the plant, demonstrate for the first time that Se-induced reduction in soil MeHg levels (i.e., MeHg-Se antagonism in soil) rather than MeHg-Se interactions within the plant might be the key process triggering the decreased grain MeHg levels under Se amendment. The reduction in soil MeHg concentrations could be mainly attributed to the formation of Hg-Se complexes (detected by TEM-EDX and XANES) and thus reduced microbial MeHg production. Moreover, selenite and selenate were equally effective in reducing soil MeHg concentrations, possibly because of rapid changes in Se speciation. The dominant role of Se-induced reduction in soil MeHg levels, which has been largely underestimated previously, together with the possible mechanisms advance our mechanistic understanding about MeHg dynamics in soil-rice systems. PMID:26778218

A Novel Selenocystine-Accumulating Plant in Selenium-Mine Drainage Area in Enshi, China

PubMed Central

Yuan, Linxi; Zhu, Yuanyuan; Lin, Zhi-Qing; Banuelos, Gary; Li, Wei; Yin, Xuebin

2013-01-01

Plant samples of Cardamine hupingshanesis (Brassicaceae), Ligulariafischeri (Ledeb.) turcz (Steraceae) and their underlying top sediments were collected from selenium (Se) mine drainage areas in Enshi, China. Concentrations of total Se were measured using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) and Se speciation were determined using liquid chromatography/UV irradiation-hydride generation-atomic fluorescence spectrometry (LC-UV-HG-AFS). The results showed that C. hupingshanesis could accumulate Se to 239±201 mg/kg DW in roots, 316±184 mg/kg DW in stems, and 380±323 mg/kg DW in leaves, which identifies it as Se secondary accumulator. Particularly, it could accumulate Se up to 1965±271 mg/kg DW in leaves, 1787±167 mg/kg DW in stem and 4414±3446 mg/kg DW in roots, living near Se mine tailing. Moreover, over 70% of the total Se accumulated in C. hupingshanesis were in the form of selenocystine (SeCys2), increasing with increased total Se concentration in plant, in contrast to selenomethionine (SeMet) in non-accumulators (eg. Arabidopsis) and secondary accumulators (eg. Brassica juncea), and selenomethylcysteine (SeMeCys) in hyperaccumulators (eg. Stanleya pinnata). There is no convincing explanation on SeCys2 accumulation in C. hupingshanesis based on current Se metabolism theory in higher plants, and further study will be needed. PMID:23750270

Effect of organic and inorganic selenium supplementation on semen quality and blood enzymes in buffalo bulls.

PubMed

El-Sharawy, Mohamed; Eid, Entsar; Darwish, Samy; Abdel-Razek, Ibrahim; Islam, Md Rashedul; Kubota, Kaiyu; Yamauchi, Nobuhiko; El-Shamaa, Ibrahim

2017-07-01

The present study aimed to evaluate the effect of organic and inorganic selenium (Se) supplementation on semen quality and blood serum profiles of buffalo bulls. Nine mature buffalo bulls were divided into three groups: control (non-supplemented); organic Se (10 mg Sel-Plex®/head twice weekly) and inorganic Se (10 mg sodium selenite/head twice weekly). Semen was collected twice a week for 3 months during Se supplementation. Semen properties were evaluated from fresh ejaculate. Moreover, fructose concentration, aspartate and alanine transaminase (AST and ALT) activities, total protein and total cholesterol were assayed in seminal plasma. Additionally AST, ALT, testosterone and Se levels were determined in the blood serum. Results showed that Se supplementation significantly (P < 0.05) influences the semen parameters during 3 months of treatment. Organic Se significantly (P < 0.05) increased the percentage of viable sperms compared to inorganic Se and the control group. Fructose concentration was significantly higher (P < 0.05) in the seminal plasma of organic Se-treated bulls. Serum testosterone and Se concentrations were significantly (P < 0.05) increased in the Se supplemented groups than the control group. In conclusion, Se supplementation improved the parameters of buffalo bull semen and more precisely, organic Se was more effective for the improvement of semen quality and some blood components than inorganic Se. © 2016 Japanese Society of Animal Science.

Manganese

MedlinePlus

... de Manganèse, Dioxyde de Manganèse, Gluconate de Manganèse, Glycérophosphate de Manganèse, Manganèse, Manganese Amino Acid Chelate, Manganese ... Chloridetetrahydrate, Manganese Citrate, Manganese Dioxide, Manganese ... Sulfate, Manganese Sulfate Monohydrate, Manganese Sulfate Tetrahydrate, ...

Selenium content in blood fractions and liver of beef heifers is greater with a mix of inorganic/organic or organic versus inorganic supplemental selenium but the time required for maximal assimilation is tissue-specific.

PubMed

Brennan, Kristen M; Burris, Walter R; Boling, James A; Matthews, James C

2011-12-01

Selenium (Se) content of feedstuffs is dependent on the Se level of the soil. Even though Se in grass and forage crops is primarily present in organic forms, Se is commonly supplemented in cattle diets in an inorganic (sodium selenite) form in geographic regions where Se soil concentrations are low. The purpose of this study was to answer two important questions about inorganic (ISe) vs organic (OSe) forms of dietary supplementation of Se (3 mg/day) to growing beef heifers (0.5 kg/day): (1) what would the effect of supplementing Se with an equal blend of ISe:OSe (Mix) have on Se tissue concentrations and (2) how long does it take for the greater assimilation with OSE to occur and stabilize? A long-term (224 day) Se dietary supplementation trial was conducted with serial sampling performed (days 28, 56, 112, and 224) to determine the length of time required to achieve Se supplement (OSE, Mix, and ISe)-dependent changes in Se assimilation in blood fractions and liver tissue. Forty maturing Angus heifers were fed a corn silage-based diet for 98 days with no Se supplementation, and then a cracked corn/cottonseed hull-based diet (basal diet) without Se supplementation for 74 days. Liver biopsies were taken for Se analysis, and heifers were fed the same diet for another 14 days. Heifers were assigned (n = 10) to one of four Se treatment groups such that basal liver Se contents were stratified among groups, and then fed enough of the basal diet (0.08 mg Se per day) and a mineral-vitamin mix that provided 0.16 (control) or 3.0 mg Se per day in ISe (sodium selenite), OSe (Sel-Plex(®)), or Mix (1:1 ISe:OSe) form to support 0.5 kg/day growth for 224 days. More Se was found in whole blood, red blood cells, serum, and liver of Mix and OSe heifers than ISe heifers, and all were greater than control. Se content either increased until day 56 then was stable (liver and plasma), or was stable until day 56 (whole blood) or day 112 (red blood cells) and then increased steadily through day 224, for all supplemental Se treatments. These data indicate that a 1:1 mix (1.5 mg Se:1.5 mg Se) of supplemental ISe and OSe is equal to 3 mg/day OSe supplementation and greater than 3 mg/day ISe supplementation. The data also indicate that Se levels stabilized in liver and plasma by 56 to 112 days whereas whole blood and red blood cell concentrations were still increasing through 224 days of supplementation, regardless of the form of supplemental Se.

Testing the Late-Veneer hypothesis with selenium isotopes

NASA Astrophysics Data System (ADS)

Labidi, J.; Koenig, S.; Bennett, N.; Kurzawa, T.; Aierken, E.; Shahar, A.; Schoenberg, R.

2016-12-01

Selenium (Se) is a siderophile element displaying an excess abundance in Earth's mantle compared to experimental predictions [1], which may be attributed to the Late-Veneer. As Se is also volatile, testing the late-veneer addition of Se can constrain the origin of other volatile elements on Earth. Here we combine high-precision Se isotope measurements of metal-silicate partitioning experiments and chondrites to assess whether planetary differentiation could leave a measurable Se isotopic signature on planetary mantles. We performed Se isotopic measurements of 5 metal-silicate partitioning experiments and 20 chondrites of all major classes. Experiments were conducted at 1 GPa and 1650 C for 1 to 4 hours using the piston-cylinder apparatus at Carnegie's Geophysical Laboratory. After wet chemistry, data were obtained on a ThermoFisher Scientific™ NeptunePlus MC-ICP-MS at the University of Tübingen with a 74Se/77Se double spike technique. δ82/76Se values are given relative to NIST SRM-3149 and the external reproducibility calculated from duplicate meteorite analyses is ≤ 0.1‰ (2 s.d.). Chondrites vary over a 0.8‰ range of δ82/76Se values. CIs and CMs show evidence for heavier 82Se/76Se ratios, likely due to mixing processes in the proto-planetary nebula. When these isotopically heavier meteorites are excluded, remaining chondrites have δ82/76Se values varying over a 0.3‰ range, within uncertainty of previous results [2]. We suggest that these chondrites may be used to estimate a δ82/76Se value of bulk planets. At the conditions of our experiments, the partition coefficients for Se log Dmetal-silicate range from 0.7±0.1 to 1.9±0.1, consistent with previous work [1]. A small but resolvable Se isotopic fractionation was observed: 82Se/76Se ratios were enriched by ≤ 0.5‰ in the silicates relative to the metals. Thus, given current uncertainties for Se isotopic measurements, marginal differences between planetary mantles and chondrites may be resolved. [1] Rose-Weston et al. 2009, GCA, 73(15), 4598-4615. [2] Vollstaedt et al. 2016, 450, 372-380.

Selenium speciation profiles in biofortified sangiovese wine.

PubMed

Fontanella, Maria Chiara; D'Amato, Roberto; Regni, Luca; Proietti, Primo; Beone, Gian Maria; Businelli, Daniela

2017-09-01

Biofortification is an agronomic-based strategy, utilized by farmers, to produce selenium (Se)-enriched food products that may help reduce dietary deficiencies of Se occurring throughout susceptible regions of the world. The foliar exposure route application ensures a high efficiency of Se assimilation by the plant since it does not depend on root-to-shoot translocation. In this study we treated grapevines of Sangiovese variety in the pre-flowering period with sodium selenate (100mg Se L -1 ). Se content was measured in leaves, fruit at harvest time and in wine respectively in treated and not treated samples with ICP-MS. At harvest, a higher amount of Se in the treated leaves compared to untreated ones was found, 16.0±3.1mgkg -1 dry weight (dw) against 0.17±0.006mgkg -1 dw in the untreated ones. The treated grapes had a content of Se of 0.800±0.08mgkg -1 dw, while that untreated one 0.065±0.025mgkg -1 dw. Immediately after the malolactic fermentation, the wine obtained from treated and untreated vines had a Se content of 0.620±0.09mg Se L -1 and 0.024±0.010mg Se L -1 respectively. In our case the percentage of inorganic Se is 26% of the total Se in the untreated wine, while in Se enriched wine this percentage increase to 47.5% of the total Se. The Se(VI) was the inorganic chemical form more present in enriched wine, probably due to foliar application with selenate. Distributions of Se species suggested being careful to the choice of the enrichment solutions to promote a balanced distribution of different chemical forms, perhaps favouring the accumulation of organic forms. Copyright © 2016 Elsevier GmbH. All rights reserved.

Effects of dietary organic, inorganic, and nanoparticulate selenium sources on growth, hemato-immunological, and serum biochemical parameters of common carp (Cyprinus carpio).

PubMed

Saffari, Sadegh; Keyvanshokooh, Saeed; Zakeri, Mohammad; Johari, Seyed Ali; Pasha-Zanoosi, Hossein; Mozanzadeh, Mansour Torfi

2018-04-16

An 8-week feeding trial was conducted to compare the effects of supplementing (0.7 mg kg -1 ) different dietary selenium (Se) sources including organic [selenomethionine (SeMet)], inorganic [sodium selenite (Na 2 SeO 3 )], and nanoparticulate Se (nano-Se) on physiological responses of common carp, Cyprinus carpio juveniles (9.7 ± 0.1 g). Basal diet without Se supplementation used as control. Fish fed nano-Se supplemented diet had the highest weight gain (97.2 ± 10.8%) and feed efficiency ratio (42.4 ± 0.8%). Intestinal villi height was significantly taller in fish fed nano-Se diet than in the control group in both foregut and midgut sections. Serum glutathione peroxidase and superoxide dismutase activities were significantly higher in nano-Se and SeMet groups than in control and sodium selenite groups. Fish fed Se-supplemented diets had greater red blood cell counts and hematocrit and hemoglobin values than the control group (P < 0.05). Nano-Se and SeMet groups showed a significant increase in white blood cell counts, neutrophil percentage, and serum lysozyme activity than the other groups. Fish fed nano-Se diet had the highest serum hemolytic activity, total immunoglobulin, and total protein and albumin contents, as well as the lowest serum total cholesterol and low density lipoprotein levels (P < 0.05). Overall, significant improvements in growth performance, feed utilization, intestinal morphology, and hemato-immunological and serum biochemical parameters of common carp juveniles suggest nano-Se as an efficient source for providing dietary Se in this species.

Selenium speciation in radix puerariae using ultrasonic assisted extraction combined with reversed phase high performance liquid chromatography-inductively coupled plasma-mass spectrometry after magnetic solid-phase extraction with 5-sulfosalicylic acid functionalized magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Cao, Yupin; Yan, Lizhen; Huang, Hongli; Deng, Biyang

2016-08-01

A new method for determination of selenium species in radix puerariae was described. The method consists of sample enrichment with 5-sulfosalicylic acid (SSA)-functionalized silica-coated magnetic nanoparticles (SMNPs), high performance liquid chromatography (HPLC) separation, and online detection using inductively coupled plasma mass spectrometry (ICP-MS). The selenium species were extracted using ultrasonic extraction system with a mixture of protease K and lipase. The SSA-SMNPs were used to enrich trace amounts of selenite [Se(IV)], selenate [Se(VI)], selenomethionine (SeMet), and selenocystine (SeCys2) from lower selenium containing samples. Under the optimal conditions, the limits of detection (3σ) for SeCys2, Se(IV), SeMet and Se(VI) were observed as 0.0023, 0.0015, 0.0043, and 0.0016 ng mL- 1, respectively. The RSD values (n = 6) of method for intraday were observed between 0.5% and 0.9%. The RSD values of method for interday were less than 1.3%. The linear concentration ranges for SeCys2, Se(IV), SeMet and Se(VI) were 0.008-1000, 0.005-200, 0.015-500 and 0.006-200 ng mL- 1, respectively. The detection limits of this method were improved by 10 times due to the enrichment with the SSA-SMNP extraction. The contents of SeCys2, Se(IV), SeMet, and Se(VI) in radix puerariae were determined as 0.0140, 0.171, 0.0178, and 0.0344 μg g- 1, respectively. The recoveries were in the range of 95.6%-99.4% and the RSDs (n = 6) of recoveries were less than 1.5%.

Selenium deposition kinetics of different selenium sources in muscle and feathers of broilers.

PubMed

Couloigner, Florian; Jlali, Maamer; Briens, Mickael; Rouffineau, Friedrich; Geraert, Pierre-André; Mercier, Yves

2015-11-01

The objective of this study was to determine selenium (Se) deposition kinetics in muscles and feathers of broilers in order to develop a rapid method to compare bioavailability of selenium sources. Different Se sources such as 2-hydroxy-4-methylselenobutanoic acid (HMSeBA, SO), sodium selenite (SS) and seleno-yeast (SY) were compared for their kinetics on Se deposition in muscles and feathers in broiler chicks from 0 to 21 d of age. A total of 576 day-old broilers were divided into four treatments with 8 replicates of 18 birds per pen. The diets used in the experiment were a negative control (NC) not supplemented with Se and 3 diets supplemented with 0.2 mg Se/kg as SS, SY or SO. Total Se content in breast muscle and feathers were assessed on days 0, 7, 14 and 21. At 7 d of age, SO increased muscle Se content compared to D0 (P < 0.05), whereas with the other treatments, muscle Se concentration decreased (P < 0.05). After 21 days, organic Se sources maintained (SY) or increased (SO) (P < 0.05) breast muscle Se concentration compared to hatch value whereas inorganic source (SS) or non-supplemented group (NC) showed a significant decrease in tissue Se concentration (P < 0.05). At D21, Se contents of muscle and feathers were highly correlated (R(2) = 0.927; P < 0.0001). To conclude, these results indicate that efficiency of different Se sources can be discriminated through a 7 d using muscle Se content in broiler chickens. Muscle and feathers Se contents were highly correlated after 21 days. Also feather sampling at 21 days of age represents a reliable and non-invasive procedure for Se bioefficacy comparison. © 2015 Poultry Science Association Inc.

Extraction, characterization and antioxidant activities of Se-enriched tea polysaccharides.

PubMed

Wang, Yuanfeng; Li, Yongfu; Liu, Yangyang; Chen, Xueqing; Wei, Xinlin

2015-01-01

Se-polysaccharides from Se-enriched tea leaves were purified by DEAE-sepharose fast flow gel column (2.5×60cm) and three polysaccharide fractions (Se-TPS1, Se-TPS2, and Se-TPS3) were isolated and purified with yields of 6.5, 37.14, and 8.57%, respectively. The average sizes of Se-TPS1 and Se-TPS2 were determined by HPGPC system, with molecular weights of 1.1×10(5) and 2.4×10(5)Da, respectively. Se-TPS3 was a polysaccharide polymer with two peaks with molecular weights of 9.2×10(5) and 2.5×10(5)Da. Monosaccharide components analysis by ion chromatography revealed Se-polysaccharides were acidic polysaccharoses and different from each other in monosaccharide kinds and molar ratio. Elements of Se, C, H, N, S, and 14 kinds of mineral elements were analyzed by AFS, EA, and ICP-AES, respectively. Spectral analysis (IR and UV) indicated Se-polysaccharides were typical glycoproteins. Morphological analyses of the samples were determined by SEM and AFM. In addition, the DPPH and superoxide radicals scavenging activities were also discussed to assess antioxidant activities of the samples, and Se-polysaccharides showed higher antioxidant activities compared to the ordinary polysaccharides. Copyright © 2015 Elsevier B.V. All rights reserved.

Distribution and metabolism of selenite and selenomethionine in the Japanese quail.

PubMed

Anan, Yasumi; Ohbo, Ai; Tani, Yuta; Hatakeyama, Yoshiko; Yawata, Ayako; Ogra, Yasumitsu

2012-05-01

Compared to the many studies on the physiological and toxicological effects of selenium (Se) in mammals, avian Se metabolism is still an unexplored topic. Some birds are useful as poultry for human nutrition. Moreover, birds belong to higher trophic levels in the biosphere and thus may play an important role in Se circulation in the ecosystem in the same way as mammals do. In this study, we analyzed the distribution and metabolism of Se in an experimental bird, the Japanese quail, which was fed drinking water containing sodium selenite or selenomethionine (SeMet). The highest concentration of Se was detected in the pancreas, followed by down feathers, liver, and kidneys. SeMet was more efficiently incorporated into the quail than selenite. The specific and preferable distribution of Se to the high molecular weight fraction in the serum of the quail was observed only in the SeMet-ingestion group. As in mammals, selenosugar and trimethylselenonium were the major metabolites in quail excreta. Three unknown Se metabolites were detected by HPLC-ICP-MS. Although part of the metabolic pathway of Se in the Japanese quail fed selenite and SeMet was the same as that observed in mammals, the bird also showed certain avian-specific metabolic process for Se.

Biological activity of selenium: Revisited.

PubMed

Wrobel, Jagoda K; Power, Ronan; Toborek, Michal

2016-02-01

Selenium (Se) is an essential micronutrient that exerts multiple and complex effects on human health. Se is essential for human well-being largely due to its potent antioxidant, anti-inflammatory, and antiviral properties. The physiological functions of Se are carried out by selenoproteins, in which Se is specifically incorporated as the amino acid, selenocysteine. Importantly, both beneficial and toxic effects of Se have been reported suggesting that the mode of action of Se is strictly chemical form and concentration dependent. Additionally, there is a relatively narrow window between Se deficiency and toxicity and growing evidence suggests that Se health effects depend greatly on the baseline level of this micronutrient. Thus, Se supplementation is not an easy task and requires an individualized approach. It is essential that we continue to explore and better characterize Se containing compounds and mechanisms of action, which could be crucial for disease prevention and treatment. © 2015 International Union of Biochemistry and Molecular Biology.

Physics of bandgap formation in Cu-Sb-Se based novel thermoelectrics: the role of Sb valency and Cu d levels.

PubMed

Do, Dat; Ozolins, Vidvuds; Mahanti, S D; Lee, Mal-Soon; Zhang, Yongsheng; Wolverton, C

2012-10-17

In this paper we discuss the results of ab initio electronic structure calculations for Cu(3)SbSe(4) (Se4) and Cu(3)SbSe(3) (Se3), two narrow bandgap semiconductors of thermoelectric interest. We find that Sb is trivalent in both the compounds, in contrast to a simple nominal valence (ionic) picture which suggests that Sb should be 5 + in Se4. The gap formation in Se4 is quite subtle, with hybridization between Sb 5s and the neighboring Se 4s, 4p orbitals, position of Cu d states, and non-local exchange interaction, each playing significant roles. Thermopower calculations show that Se4 is a better p-type system. Our theoretical results for Se4 agree very well with recent experimental results obtained by Skoug et al (2011 Sci. Adv. Mater. 3 602).

Aqueous synthesis of high bright and tunable near-infrared AgInSe2-ZnSe quantum dots for bioimaging.

PubMed

Che, Dongchen; Zhu, Xiaoxu; Wang, Hongzhi; Duan, Yourong; Zhang, Qinghong; Li, Yaogang

2016-02-01

Efficient synthetic methods for near-infrared quantum dots with good biophysical properties as bioimaging agents are urgently required. In this work, a simple and fast synthesis of highly luminescent, near-infrared AgInSe2-ZnSe quantum dots (QDs) with tunable emissions in aqueous media is reported. This method avoids high temperature and pressure and organic solvents to directly generate water-dispersible AgInSe2-ZnSe QDs. The photoluminescence emission peak of the AgInSe2-ZnSe QDs ranged from 625 to 940nm, with quantum yields up to 31%. The AgInSe2-ZnSe QDs with high quantum yield, near-infrared and low cytotoxic could be used as good cell labels, showing great potential applications in bio-imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

Selenium Nanoparticles Formed by Modulation of Carrageenan Enhance Osteogenic Differentiation of Mesenchymal Stem Cells.

PubMed

Kim, Jin; Lee, Ki-Young; Lee, Chang-Moon

2016-03-01

Fabrication of nano-sized selenium (Se) particles may help to expend the applications of Se. In this study, we focused on the preparation and characterization of Se nanoparticles (Se NPs) modulated with carrageenan (CA). Furthermore, their influence on osteoblast cell growth was investigated in vitro. Spherical Se-NPs, of 100-200 nm diameter, were prepared simply by adding κ-, ι-, and λ-CA, which has sulfate groups, hydroxyl groups, and carboxyl groups. CA-modulated Se NPs (CA-Se NPs) were readily suspended in liquid medium with no precipitation over long time periods. In particular, it was found through Alizarin Red S staining that the growth of osteoblast D1 cells treated with λ-CA-Se NPs was improved significantly. These results suggest that Se NPs can be prepared simply, using CA, have good suspension stability in liquid medium, and λ-CA-Se NPs may induce the growth of osteoblast cells.

Band lineup of lattice mismatched InSe/GaSe quantum well structures prepared by van der Waals epitaxy: Absence of interfacial dipoles

NASA Astrophysics Data System (ADS)

Lang, O.; Klein, A.; Pettenkofer, C.; Jaegermann, W.; Chevy, A.

1996-10-01

Epitaxial growth of the strongly lattice mismatched (6.5%) layered chalcogenides InSe and GaSe on each other is obtained with the concept of van der Waals epitaxy as proven by low-energy electron diffraction and scanning tunnel microscope. InSe/GaSe/InSe and GaSe/InSe/GaSe quantum well structures were prepared by molecular beam epitaxy and their interface properties were characterized by soft x-ray photoelectron spectroscopy. Valence and conduction band offsets are determined to be 0.1 and 0.9 eV, respectively, and do not depend on deposition sequence (commutativity). As determined from the measured work functions the interface dipole is 0.05 eV; the band lineup between the two materials is correctly predicted by the Anderson model (electron affinity rule).

Prevalence and correlates of treatment failure among Kenyan children hospitalised with severe community-acquired pneumonia: a prospective study of the clinical effectiveness of WHO pneumonia case management guidelines

PubMed Central

Agweyu, Ambrose; Kibore, Minnie; Digolo, Lina; Kosgei, Caroline; Maina, Virginia; Mugane, Samson; Muma, Sarah; Wachira, John; Waiyego, Mary; Maleche-Obimbo, Elizabeth

2014-01-01

Objective To determine the extent and pattern of treatment failure (TF) among children hospitalised with community-acquired pneumonia at a large tertiary hospital in Kenya. Methods We followed up children aged 2–59 months with WHO-defined severe pneumonia (SP) and very severe pneumonia (VSP) for up to 5 days for TF using two definitions: (i) documentation of pre-defined clinical signs resulting in change of treatment (ii) primary clinician's decision to change treatment with or without documentation of the same pre-defined clinical signs. Results We enrolled 385 children. The risk of TF varied between 1.8% (95% CI 0.4–5.1) and 12.4% (95% CI 7.9–18.4) for SP and 21.4% (95% CI 15.9–27) and 39.3% (95% CI 32.5–46.4) for VSP depending on the definition applied. Higher rates were associated with early changes in therapy by clinician in the absence of an obvious clinical rationale. Non-adherence to treatment guidelines was observed for 70/169 (41.4%) and 67/201 (33.3%) of children with SP and VSP, respectively. Among children with SP, adherence to treatment guidelines was associated with the presence of wheeze on initial assessment (P = 0.02), while clinician non-adherence to guideline-recommended treatments for VSP tended to occur in children with altered consciousness (P < 0.001). Using propensity score matching to account for imbalance in the distribution of baseline clinical characteristics among children with VSP revealed no difference in TF between those treated with the guideline-recommended regimen vs. more costly broad-spectrum alternatives [risk difference 0.37 (95% CI −0.84 to 0.51)]. Conclusion Before revising current pneumonia case management guidelines, standardised definitions of TF and appropriate studies of treatment effectiveness of alternative regimens are required. Objectif Déterminer l'ampleur et les caractéristiques de l’échec du traitement (ET) chez les enfants hospitalisés avec une pneumonie acquise dans la communauté dans un grand hôpital tertiaire du Kenya. Méthodes Nous avons suivi des enfants âgés de 2 à 59 mois avec une pneumonie sévère (PS) et une pneumonie très sévère (PTS) telles que définies par l’OMS, sur un maximum de cinq jours pour l’ET, en utilisant deux définitions: (a) documentation des signes cliniques prédéfinis ayant entraîné un changement du traitement, (b) décision primaire du clinicien de changer de traitement avec ou sans documentation des mêmes signes cliniques prédéfinis. Résultats Nous avons recruté 385 enfants. Le risque d’ET variait de 1,8% (IC95%: 0,4 à 5,1) à 12,4% (IC95%: 7,9 à 18,4) pour la PS et de 21,4% (IC95%: 15,9 à 27) à 39,3% (IC95%: 32,5 à 46,4) pour la PTS selon la définition appliquée. Des taux plus élevés étaient associés à des changements précoces du traitement par le clinicien en l'absence d'une justification clinique évidente. Le non-respect des directives de traitement a été observé pour 70/169 (41,4%) et 67/201 (33,3%) enfants avec une PS et une PTS respectivement. Chez les enfants avec une PS, le respect des directives de traitement était associé avec la présence d'une respiration sifflante au cours l’évaluation initiale (P = 0,02) tandis que le non respect par les cliniciens des traitements recommandés pour la PTS tendait à se produire chez les enfants avec une altération de la conscience (P <0,001). L'utilisation du score de propension correspondant pour tenir compte du déséquilibre dans la répartition des caractéristiques cliniques de base chez les enfants avec une PTS n'a révélé aucune différence dans l’ET entre ceux traités avec le régime recommandé par les directives et ceux traités par des alternatives plus coûteuses à large spectre (différence de risque: 0,37 (IC95%: -0,84 à 0,51). Conclusion Avant la révision des directives actuelles de prise en charge des cas de pneumonie, des définitions standard d’ET et des études appropriées de l'efficacité des traitements alternatifs sont nécessaires. Objetivo Determinar la extensión y el patrón del fallo en el tratamiento (FT) en niños hospitalizados con una neumonía adquirida en la comunidad, ingresados en un gran hospital terciario de Kenia. Métodos Hemos seguido a niños con edades entre los 2-59 meses con una neumonía severa (NS) y neumonía muy severa (NMS) según definición de la OMS de hasta cinco días para FT utilizando dos definiciones: (a) documentación de signos clínicos pre-definidos que resultaron en un cambio de tratamiento (b) decisión del clínico principal de cambiar el tratamiento con o sin documentación de los mismos signos clínicos pre-definidos. Resultados Incluimos a 385 niños. El riesgo de FT varió entre un 1.8% (IC 95% 0.4 a 5.1) y 12.4% (IC 95% 7.9 a 18.4) para NS y 21.4% (IC 95% 15.9 a 27) y 39.3% (IC 95% 32.5 a 46.4) para NMS dependiendo de la definición que se aplicase. Unas mayores tasas estaban asociadas con cambios tempranos en la terapia por el clínico y en ausencia de un razonamiento clínico obvio. Se observaba una no adherencia a las guías de tratamiento en 70/169 (41.4%) y 67/201 (33.3%) de los niños con NS y NMS respectivamente. Entre los niños con SP, la adherencia a las guías de tratamiento estaba asociada con la presencia de sibilancias en la evaluación inicial (P=0.02) mientras que la no adherencia del clínico a los tratamientos recomendados por las guías para NMS tendían a ocurrir en niños con un estado alterado de consciencia (P<0.001). Utilizando el pareamiento por puntaje de propensión para equilibrar los grupos en la distribución de las características clínicas de base de los niños con NMS, se observó que no existían diferencias en FT entre aquellos tratados con el régimen recomendado por las guías versus alternativas más costosas de amplio espectro (diferencias de riesgo 0.37 (IC 95% -0.84 a 0.51). Conclusión Antes de revisar las actuales guías de manejo de casos de neumonía, se requieren definiciones estandarizadas de FT y estudios apropiados de la efectividad del tratamiento de regímenes alternativos. PMID:25130866

Response of duckweed to various concentrations of selenite.

PubMed

Mechora, Špela; Stibilj, Vekoslava; Germ, Mateja

2015-02-01

The uptake of Se(IV) and its effects on the physiological and biochemical characteristics of duckweed (Lemna minor L.) have been studied. Duckweed plants were cultivated in controlled conditions for 7 weeks in different concentrations of Na selenite: 0.5, 1, 2, 5 (exposed 42 days) and 10 mg Se L(-1) (survived 7-21 days). The addition of 1 mg Se L(-1) did not negatively affect photochemical efficiency whilst respiratory potential increased in weeks 2-4 compared to control. The addition of 1 mg Se(IV) L(-1) increased the amount of chlorophyll a in weeks 3 and 4 and the amount of carotenoids in weeks 1, 3 and 5. Concentrations of 2 and 5 mg Se L(-1) negatively affected photochemical efficiency in weeks 3 and 4, and increased respiratory potential in comparison to the control in weeks 1-4, whilst beyond week 4, the respiratory potential decreased. Plants exposed to the highest concentration of Se(IV) had to be replaced twice during the experiment because they were dying. That was reflected in photochemical efficiency as well as in respiratory potential, which decreased in time. The content of Se in duckweed increased with the increasing concentration of Se: plants growing in 0.5 mg Se L(-1) contained 0.9 mg Se g(-1) DM and plants exposed to 5 mg Se L(-1) contained 5.8 mg Se g(-1) DM. The group of plants exposed to 10 mg Se L(-1) for 21 days contained 19.5 mg Se g(-1) DM. Our study revealed that duckweed absorbed high amount of Se(IV) from the water.

Attempting to realize n-type BiCuSeO

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxuan; Feng, Dan; He, Jiaqing; Zhao, Li-Dong

2018-02-01

As an intrinsic p-type semiconductor, BiCuSeO has been widely researched in the thermoelectric community, however, n-type BiCuSeO has not been reported so far. In this work, we successfully realized n-type BiCuSeO through carrying out several successive efforts. Seebeck coefficient of BiCuSeO was increased through introducing extra Bi/Cu to fill the Bi/Cu vacancies that may produce holes, and the maximum Seebeck coefficient was increase from +447 μVK-1 for undoped BiCuSeO to +638 μVK-1 for Bi1.04Cu1.05SeO. The Seebeck coefficient of Bi1.04Cu1.05SeO was changed from p-type to n-type through electron doping through introducing Br/I in Se sites, the maximum negative Seebeck coefficient can reach ∼ -465 μVK-1 and -543 μVK-1 for Bi1.04Cu1.05Se1-xIxO and Bi1.04Cu1.05Se1-xBrxO, respectively. Then, after compositing Bi1.04Cu1.05Se0.99Br0.01O with Ag, n-type BiCuSeO can be absolutely obtained in the whole temperature range of 300-873 K, the maximum ZT 0.05 was achieved at 475 K in the Bi1.04Cu1.05Se0.99Br0.01O+15% Ag. Our report indicates that it is possible to realize n-type conducting behaviors in BiCuSeO system.

Room Temperature Intrinsic Ferromagnetism in Epitaxial Manganese Selenide Films in the Monolayer Limit

NASA Astrophysics Data System (ADS)

O'Hara, Dante J.; Zhu, Tiancong; Trout, Amanda H.; Ahmed, Adam S.; Luo, Yunqiu Kelly; Lee, Choong Hee; Brenner, Mark R.; Rajan, Siddharth; Gupta, Jay A.; McComb, David W.; Kawakami, Roland K.

2018-05-01

Monolayer van der Waals (vdW) magnets provide an exciting opportunity for exploring two-dimensional (2D) magnetism for scientific and technological advances, but the intrinsic ferromagnetism has only been observed at low temperatures. Here, we report the observation of room temperature ferromagnetism in manganese selenide (MnSe$_x$) films grown by molecular beam epitaxy (MBE). Magnetic and structural characterization provides strong evidence that in the monolayer limit, the ferromagnetism originates from a vdW manganese diselenide (MnSe$_2$) monolayer, while for thicker films it could originate from a combination of vdW MnSe$_2$ and/or interfacial magnetism of $\\alpha$-MnSe(111). Magnetization measurements of monolayer MnSe$_x$ films on GaSe and SnSe$_2$ epilayers show ferromagnetic ordering with large saturation magnetization of ~ 4 Bohr magnetons per Mn, which is consistent with density functional theory calculations predicting ferromagnetism in monolayer 1T-MnSe$_2$. Growing MnSe$_x$ films on GaSe up to high thickness (~ 40 nm) produces $\\alpha$-MnSe(111), and an enhanced magnetic moment (~ 2x) compared to the monolayer MnSe$_x$ samples. Detailed structural characterization by scanning transmission electron microscopy (STEM), scanning tunneling microscopy (STM), and reflection high energy electron diffraction (RHEED) reveal an abrupt and clean interface between GaSe(0001) and $\\alpha$-MnSe(111). In particular, the structure measured by STEM is consistent with the presence of a MnSe$_2$ monolayer at the interface. These results hold promise for potential applications in energy efficient information storage and processing.

The role of selenium in protecting plants against prairie dog herbivory: implications for the evolution of selenium hyperaccumulation.

PubMed

Quinn, Colin F; Freeman, John L; Galeas, Miriam L; Klamper, Erin M; Pilon-Smits, Elizabeth A H

2008-03-01

Some plants can hyperaccumulate the element selenium (Se) up to 10,000 mg Se kg(-1) dry weight. Hyperaccumulation has been hypothesized to defend against herbivory. In laboratory studies high Se levels protect plants from invertebrate herbivores and pathogens. However, field studies and mammalian herbivore studies that link Se accumulation to herbivory protection are lacking. In this study a combination of field surveys and manipulative field studies were carried out to determine whether plant Se accumulation in the field deters herbivory by black-tailed prairie dogs (Cynomys ludovicianus). The Se hyperaccumulator Astragalus bisulcatus (two-grooved milkvetch) occurs naturally on seleniferous soils in the Western USA, often on prairie dog colonies. Field surveys have shown that this Se hyperaccumulator is relatively abundant on some prairie dog colonies and suffers less herbivory than other forb species. This protection was likely owing to Se accumulation, as judged from subsequent manipulative field experiments. When given a choice between pairs of plants of the Se hyperaccumulator Stanleya pinnata (prince's plume) that were pretreated with or without Se, prairie dogs preferred to feed on the plants with low Se; the same results were obtained for the non-hyperaccumulator Brassica juncea (Indian mustard). Plants containing as little as 38 mg Se kg(-1) DW were protected from herbivory. Taken together these results shed light on the functional significance of Se hyperaccumulation and the possible selection pressures driving its evolution. They also have implications for the use of plants in Se phytoremediation, or as Se-fortified crops.

Bioavailability of seleno-compounds in the lactating rat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, A.M.; Picciano, M.F.

Previously the authors reported an increased selenium (Se) requirement for lactating rats of at least 0.2 ppm dietary Se if provided as selenite (SEL). In the present study bioavailability of selenomethionine (SEM), Se yeast (SEY) and SEL was assessed. A casein-based diet (0.025 ppm Se) was fed to 9 groups of 8 rats each during pregnancy to produce a marginal Se deficiency. During lactation each group was fed the same diet containing either 0.1, 0.25, or 0.5 ppm Se as SEL, SEM, or SEY. On day 18 of lactation dams and pups were sacrificed and tissue Se and glutathione peroxidasemore » activities (GPx) determined. Although food intake of the dams and growth of the pups did not vary, selenium and GPx activities were dependent upon quantity and form of Se consumed. Using slope-ratio analysis linear increases in blood, tissue and milk Se content the bioavailabilities were SEM>SEY>SEL. Maximal GPx depended on the form of dietary Se with SEM>SEY>SEL. Maximal GPx occurred at 0.25 ppm dietary Se as SEM and SEY, but did not reach this activity when fed at 0.5 ppm Se as SEL. These results indicate that regardless of form, the NRC requirement for growing rats of 0.1 ppm Se, is not adequate during lactation to maintain maximum tissue GSH-Px in nursing pups. Based on higher tissue Se in dams and GPx in nursing pups the bioavailability of dietary Se to the lactating rat is greater when fed as SEM and SEY than as SEL.« less

Organizational Considerations for Implementing Systems Engineering and Integration in the Ares Projects Office

NASA Technical Reports Server (NTRS)

Thomas, LeAnn; Doreswamy, Rajiv N.

2008-01-01

Systems Engineering and Integration (SE&I) is a critical discipline in developing new space systems. In 2005, NASA performed an internal study of 24 agency and Department of Defense (DoD) programs to evaluate methods of integrating SE&I practices and determine their effectiveness. The goal of the study was to determine the best SE&I implementation strategy for the Ares Projects Office. The study identified six SE&I organizational structures: 1. Lead systems integrator (LSI) with SE&I responsibility and government technical insight. 2a. Integration contractor with government SE&I responsibility (government insight). 2b. Integration contractor with government SE&I responsibility (government oversight). 3a. Prime contractor with SE&I responsibility (government insight). 3b. Prime contractor with SE&I responsibility (government oversight). 3c. Prime contractor with SE&I responsibility (government/industry partnership). 4a.Prime contractor with government SE&I responsibility (government insight). 4b. Prime contractor with government SE&I responsibility (government oversight). 4d.Prime contractors with total system performance responsibility (TSPR). 5. Prime contractor with government SE&I responsibility and integration products through a Federally Funded Research and Development Center (FFRDC). 6. Government/FFRDC in-house development with SE&I responsibility and function. The organizational structure used most often was number 4, using a prime contractor with government SE&I responsibility and government technical insight. However, data analyses did not establish a positive relationship between program development costs and specific SE&I organizational types, nor did it positively determine the relationship between successful programs or projects and their SE&I structure. The SE&I study reached the following conclusions: (1) Large, long-duration, technically complex programs or projects reach their technical goals, but rarely meet schedule or cost goals. NASA's recent successes have been smaller, short-duration development projects using heritage hardware/software, focused technology development, technical oversight and stable external factors. (2) Programs and projects have failed or been terminated due to lack of technical insight, relaxing of SE&I processes, and unstable external factors. (3) The study did not find a single, clear optimum SE&I organization type to fit all projects. However, while any organizational structure can be made to work, the fewer complexities in the program, the better the likelihood of success. (4) The most common successful SE&I organization structure type in the study was type 4b, where the government maintained integration responsibility, with the prime contractor providing SE&I products and the government providing technical oversight. This study was instrumental in helping the APO select organization structure 4, following the same SE&I and oversight process used during humanlund7s last voyages to the Moon.

Multiple biological complex of alkaline extract of the leaves of Sasa senanensis Rehder.

PubMed

Sakagami, Hiroshi; Zhou, Li; Kawano, Michiyo; Thet, May Maw; Tanaka, Shoji; Machino, Mamoru; Amano, Shigeru; Kuroshita, Reina; Watanabe, Shigeru; Chu, Qing; Wang, Qin-Tao; Kanamoto, Taisei; Terakubo, Shigemi; Nakashima, Hideki; Sekine, Keisuke; Shirataki, Yoshiaki; Zhang, Chang-Hao; Uesawa, Yoshihiro; Mohri, Kiminori; Kitajima, Madoka; Oizumi, Hiroshi; Oizumi, Takaaki

2010-01-01

Previous studies have shown anti-inflammatory potential of alkaline extract of the leaves of Sasa senanensis Rehder (SE). The aim of the present study was to clarity the molecular entity of SE, using various fractionation methods. SE inhibited the production of nitric oxide (NO), but not tumour necrosis factor-α by lipopolysaccharide (LPS)-stimulated mouse macrophage-like cells. Lignin carbohydrate complex prepared from SE inhibited the NO production to a comparable extent with SE, whereas chlorophyllin was more active. On successive extraction with organic solvents, nearly 90% of SE components, including chlorophyllin, were recovered from the aqueous layer. Anti-HIV activity of SE was comparable with that of lignin-carbohydrate complex, and much higher than that of chlorophyllin and n-butanol extract fractions. The CYP3A inhibitory activity of SE was significantly lower than that of grapefruit juice and chlorophyllin. Oral administration of SE slightly reduced the number of oral bacteria. When SE was applied to HPLC, nearly 70% of SE components were eluted as a single peak. These data suggest that multiple components of SE may be associated with each other in the native state or after extraction with alkaline solution.

Anomalous correlation effects and unique phase diagram of electron-doped FeSe revealed by photoemission spectroscopy

PubMed Central

Wen, C. H. P.; Xu, H. C.; Chen, C.; Huang, Z. C.; Lou, X.; Pu, Y. J.; Song, Q.; Xie, B. P.; Abdel-Hafiez, Mahmoud; Chareev, D. A.; Vasiliev, A. N.; Peng, R.; Feng, D. L.

2016-01-01

FeSe layer-based superconductors exhibit exotic and distinctive properties. The undoped FeSe shows nematicity and superconductivity, while the heavily electron-doped KxFe2−ySe2 and single-layer FeSe/SrTiO3 possess high superconducting transition temperatures that pose theoretical challenges. However, a comprehensive study on the doping dependence of an FeSe layer-based superconductor is still lacking due to the lack of a clean means of doping control. Through angle-resolved photoemission spectroscopy studies on K-dosed thick FeSe films and FeSe0.93S0.07 bulk crystals, here we reveal the internal connections between these two types of FeSe-based superconductors, and obtain superconductivity below ∼46 K in an FeSe layer under electron doping without interfacial effects. Moreover, we discover an exotic phase diagram of FeSe with electron doping, including a nematic phase, a superconducting dome, a correlation-driven insulating phase and a metallic phase. Such an anomalous phase diagram unveils the remarkable complexity, and highlights the importance of correlations in FeSe layer-based superconductors. PMID:26952215

Age dependent mortality in the pilocarpine model of status epilepticus

PubMed Central

Blair, Robert E.; Deshpande, Laxmikant S.; Holbert, William H.; Churn, Severn B.; DeLorenzo, Robert J.

2010-01-01

Status epilepticus (SE) is an acute neurological emergency associated with significant morbidity and mortality. Age has been shown to be a critical factor in determining outcome after SE. Understanding the causes of this increased mortality with aging by developing an animal model to study this condition would play a major role in studying mechanisms to limit the mortality due to SE. Here we employed pilocarpine to induce SE in rats aged between 5 to 28 weeks. Similar to clinical studies in man, we observed that age was a significant predictor of mortality following SE. While no deaths were observed in 5-week old animals, mortality due to SE increased progressively with age and reached 90% in 28-week old animals. There was no correlation between the age of animals and severity of SE. With increasing age mortality occurred earlier after the onset of SE. These results indicate that pilocarpine-induced SE in the rat provides a useful model to study age-dependent SE-induced mortality and indicates the importance of using animal models to elucidate the mechanisms contributing to SE-induced mortality and the development of novel therapeutic interventions to prevent SE-induced death. PMID:19429042

Age-dependent mortality in the pilocarpine model of status epilepticus.

PubMed

Blair, Robert E; Deshpande, Laxmikant S; Holbert, William H; Churn, Severn B; DeLorenzo, Robert J

2009-04-10

Status epilepticus (SE) is an acute neurological emergency associated with significant morbidity and mortality. Age has been shown to be a critical factor in determining outcome after SE. Understanding the causes of this increased mortality with aging by developing an animal model to study this condition would play a major role in studying mechanisms to limit the mortality due to SE. Here we employed pilocarpine to induce SE in rats aged between 5 and 28 weeks. Similar to clinical studies in man, we observed that age was a significant predictor of mortality following SE. While no deaths were observed in 5-week-old animals, mortality due to SE increased progressively with age and reached 90% in 28-week-old animals. There was no correlation between the age of animals and severity of SE. With increasing age mortality occurred earlier after the onset of SE. These results indicate that pilocarpine-induced SE in the rat provides a useful model to study age-dependent SE-induced mortality and indicates the importance of using animal models to elucidate the mechanisms contributing to SE-induced mortality and the development of novel therapeutic interventions to prevent SE-induced death.

Effect of sucrose ester concentration on the interfacial characteristics and physical properties of sodium caseinate-stabilized oil-in-water emulsions.

PubMed

Zhao, Qiangzhong; Liu, Daolin; Long, Zhao; Yang, Bao; Fang, Min; Kuang, Wanmei; Zhao, Mouming

2014-05-15

The effect of sucrose ester (SE) concentration on interfacial tension and surface dilatational modulus of SE and sodium caseinate (NaCas)-SE solutions were investigated. The critical micelle concentration (CMC) of SE was presumed to be 0.05% by measuring interfacial tension of SE solution. The interfacial tension of NaCas-SE solution decreased with increased SE concentration. A sharp increase in surface dilatational modulus of NaCas solution was observed when 0.01% SE was added and a decline was occurred at higher SE level. The influence of SE concentration on droplet size and confocal micrograph, surface protein concentration, ζ-potential and rheological properties of oil-in-water (O/W) emulsions prepared with 1% NaCas was also examined. The results showed that addition of SE reduced droplet size and surface protein concentration of the O/W emulsions. The ζ-potential of the O/W emulsions increased initially and decreased afterward with increased SE concentration. All the O/W emulsions exhibited a shear-thinning behaviour and the data were well-fitted into the Herschel-Bulkley model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ab initio phonon thermal transport in monolayer InSe, GaSe, GaS, and alloys

NASA Astrophysics Data System (ADS)

Pandey, Tribhuwan; Parker, David S.; Lindsay, Lucas

2017-11-01

We compare vibrational properties and phonon thermal conductivities (κ) of monolayer InSe, GaSe, and GaS systems using density functional theory and Peierls-Boltzmann transport methods. In going from InSe to GaSe to GaS, system mass decreases giving both increasing acoustic phonon velocities and decreasing scattering of these heat-carrying modes with optic phonons, ultimately giving {κ }{InSe}< {κ }{GaSe}< {κ }{GaS}. This behavior is demonstrated by correlating the scattering phase space limited by fundamental conservation conditions with mode scattering rates and phonon dispersions for each material. We also show that, unlike flat monolayer systems such as graphene, in InSe, GaSe and GaS thermal transport is governed by in-plane vibrations. Alloying of InSe, GaSe, and GaS systems provides an effective method for modulating their κ through intrinsic vibrational modifications and phonon scattering from mass disorder giving reductions ˜2-3.5 times. This disorder also suppresses phonon mean free paths in the alloy systems compared to those in their crystalline counterparts. This work provides fundamental insights of lattice thermal transport from basic vibrational properties for an interesting set of two-dimensional materials.

A Novel Organic Selenium Compound Exerts Unique Regulation of Selenium Speciation, Selenogenome, and Selenoproteins in Broiler Chicks.

PubMed

Zhao, Ling; Sun, Lv-Hui; Huang, Jia-Qiang; Briens, Mickael; Qi, De-Sheng; Xu, Shi-Wen; Lei, Xin Gen

2017-05-01

Background: A new organic selenium compound, 2-hydroxy-4-methylselenobutanoic acid (SeO), displayed a greater bioavailability than sodium selenite (SeNa) or seleno-yeast (SeY) in several species. Objective: This study sought to determine the regulation of the speciation of selenium, expression of selenogenome and selenocysteine biosynthesis and degradation-related genes, and production of selenoproteins by the 3 forms of selenium in the tissues of broiler chicks. Methods: Day-old male chicks ( n = 6 cages/diet, 6 chicks/cage) were fed a selenium-deficient, corn and soy-based diet [base diet (BD), 0.05 mg Se/kg] or the BD + SeNa, SeY, or SeO at 0.2 mg Se/kg for 6 wk. Plasma, livers, and pectoral and thigh muscles were collected at weeks 3 and 6 to assay for total selenium, selenomethionine, selenocysteine, redox status, and selected genes, proteins, and enzymes. Results: Although both SeY and SeO produced greater concentrations ( P < 0.05) of total selenium (20-172%) and of selenomethionine (≤15-fold) in the liver, pectoral muscle, and thigh than those of SeNa, SeO further raised ( P < 0.05) these concentrations by 13-37% and 43-87%, respectively, compared with SeY. Compared with the BD, only SeO enhanced ( P < 0.05) the mRNA of selenoprotein ( Seleno ) s and methionine sulfoxide reductase B1 ( Msrb1 ) in the liver and thigh (62-98%) and thioredoxin reductase (TXRND) activity in the pectoral and thigh muscles (20-37%) at week 3. Furthermore, SeO increased ( P < 0.05) the expression of glutathione peroxidase ( Gpx ) 3 , GPX4, SELENOP, and SELENOU relative to the SeNa group by 26-207%, and the expression of Selenop, O-phosphoseryl-transfer RNA (tRNA):selenocysteinyl-tRNA synthase , GPX4, and SELENOP relative to the SeY group by 23-55% in various tissues. Conclusions: Compared with SeNa or SeY, SeO demonstrated a unique ability to enrich selenomethionine and total selenium depositions, to induce the early expression of Selenos and Mrsb1 mRNA and TXRND activity, and to enhance the protein production of GPX4, SELENOP, and SELENOU in the tissues of chicks. © 2017 American Society for Nutrition.

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids.

PubMed

Schiavon, Michela; Berto, Chiara; Malagoli, Mario; Trentin, Annarita; Sambo, Paolo; Dall'Acqua, Stefano; Pilon-Smits, Elizabeth A H

2016-01-01

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2-3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20-30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7-15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5-10 μM selenate supply in hydroponics. The radishes metabolized selenate to the anticarcinogenic compound Se-methyl-selenocysteine. Selenate treatment enhanced levels of other nutraceuticals in radish roots, including glucoraphanin. Therefore, Se biofortification can produce plants with superior health benefits.

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids

PubMed Central

Schiavon, Michela; Berto, Chiara; Malagoli, Mario; Trentin, Annarita; Sambo, Paolo; Dall'Acqua, Stefano; Pilon-Smits, Elizabeth A. H.

2016-01-01

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2–3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20–30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7–15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5–10 μM selenate supply in hydroponics. The radishes metabolized selenate to the anticarcinogenic compound Se-methyl-selenocysteine. Selenate treatment enhanced levels of other nutraceuticals in radish roots, including glucoraphanin. Therefore, Se biofortification can produce plants with superior health benefits. PMID:27683583

Selenium biotransformations into proteinaceous forms by foodweb organisms of selenium-laden drainage waters in California

USGS Publications Warehouse

Spallholz, J.E.; Hoffman, D.J.

2002-01-01

Selenium contamination represents one of the few clear cases where environmental pollution has led to devastation of wildlife populations, most notably in agricultural drainage evaporation and power plant coal-fly ash receiving ponds. Complex biogeochemistry, in particular extensive biotransformations and foodchain transfer, governs Se ecotoxicology and toxicology, for which the mechanism(s) are still elusive. However, total waterborne Se concentration has been widely used as a criterion for regulating and mitigating Se risk in aquatic ecosystems, which does not account for Se biogeochemistry and its site-dependence. There is a need for more reliable indicator(s) that encompass Se ecotoxicity and/or toxicity. Selenomethionine warrants special attention since it simulates Se toxicosis of wildlife in laboratory feeding studies. While low in free selenomethionine, microphytes isolated from Se-laden agricultural evaporation ponds were abundant in proteinaceous selenomethionine. This prompted a more extensive survey of Se speciation in foodchain organisms including microphytes, macroinvertebrates, fish, and bird embryos residing mainly in the agricultural drainage systems of the San Joaquin Valley, California. Total Se in biomass, water-soluble fractions, and protein-rich fractions were measured along with GC-MS analysis of proteinaceous selenomethionine. In all foodchain organisms, water-soluble Se constituted the major fraction of total biomass Se, while proteinaceous Se was a substantial, if not dominant, fraction of the water-soluble Se. In turn, proteinaceous selenomethionine comprised an important fraction of proteinaceous Se. In terms of total biomass Se, an average 1400-fold of Se biomagnification from water to microphytes was observed while subsequent transfer from microphytes to macroinvertebrates exhibited an average of only 1.9-fold. The latter transfer was more consistent and greater in extent for proteinaceous Se and proteinaceous selenomethionine, which is consistent with their importance in foodchain transfer. Proteinaceous Se in the omnivorous carp (Cyprinus carpio) liver also demonstrated a relation to ovarian lesions, while deformed stilt (Himantopus mexicanus) embryo was more abundant in proteinaceous selenomethionine than were normal embryos. Although limited in the number of organisms surveyed, these findings provide an impetus for further field and laboratory feeding studies to substantiate the hypothesis that proteinaceous selenomethionine underlies Se ecotoxicity, which may in turn prove to be a reliable indicator of Se risk in aquatic ecosystems. Copyright ?? 2002 Elsevier Science B.V.

Effect of forms of selenium on the accumulation of selenium, sulfur, and forms of nitrogen and phosphorus in forage cowpea (Vigna sinensis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, M.; Singh, N.

1979-05-01

The effects of forms of selenium on the accumulation of sulfur, selenium, and forms of nitrogen and phosphorus in cowpea (Vigna sinensis) were studied in pots in the greenhouse at Haryana Agricultural University, Hissar, India. The soil used was sandy, and forms of selenium added were Na/sub 2/SeO/sub 4/ 10H/sub 2/O, Na/sub 2/SeO/sub 3/ 5H/sub 2/O, H/sub 2/SeO/sub 3/, and elemental selenium at the rate of 0, 1, 2.5 and 5 ppM. Dry matter yield and sulfur content decreased with increased selenium application. This inhibition in plants, attributable to applied selenium, was in the order SeO/sub 4/ > H/sub 2/SeO/submore » 3/ > SeO/sub 3/ > elemental selenium. Plant selenium increased with increasing application of all forms of selenium. The highest plant selenium (11.58 ppM) was in the plants treated with SeO/sub 4/, followed by the plants treated with H/sub 2/SeO/sub 3/, SeO/sub 3/, and elemental selenium. The total plant phosphorus increased with increased selenium application in any form, but maximum phosphorus occurred in SeO/sub 3/-treated plants. The inorganic phosphorus increased similarly, the largest amount occurring in SeO/sub 4/-treated plants. Organic phosphorus decreased with selenium application; minimum concentration was recorded in SeO/sub 4/-treated plants. Soluble nitrogen decreased, relative to the control, with applications of 2.5 and 5 ppM selenium. This decrease was minimal for elemental selenium and maximum for SeO/sub 4/. Soluble nitrogen, in the case of SeO/sub 3/ was higher than for H/sub 2/SeO/sub 3/. Total plant nitrogen and protein also decreased. Amino N, amide N, and ammoniacal and nitrate N increased, compared to the control. The largest amount of all these forms was noted in SeO/sub 4/-treated plants. Overall, among the forms of selenium normally reported in soils, the SeO/sub 4/ form showed the highest inhibition, whereas SeO/sub 3/ showed less than both SeO/sub 4/ and H/sub 2/SeO/sub 3/.« less

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

USGS Publications Warehouse

Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith C.; Keith, Gabrielle L.

2016-01-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (< 0.5 μg L− 1) to 4070 μg L− 1, and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted.

Coexistence of strongly and weakly confined energy levels in (Cd,Zn)Se quantum dots: Tailoring the near-band-edge and defect-levels for white light emission

NASA Astrophysics Data System (ADS)

Das, Tapan Kumar; Ilaiyaraja, P.; Sudakar, C.

2017-05-01

We demonstrate white light emission (WLE) from (Cd,Zn)Se system, which is a composite of Zn alloyed CdSe quantum dot and ZnSe-amorphous (ZnSe-a) phase. Detailed structural and photoluminescence emission studies on pure CdSe and (Cd,Zn)Se show cubic zinc blende structure in the size range of 2.5 to 5 nm. (Cd,Zn)Se quantum dots (QDs) also have a significant fraction of ZnSe-a phase. The near-band-edge green-emission in crystalline CdSe and (Cd,Zn)Se is tunable between 500 to 600 nm. The (Cd,Zn)Se system also exhibits a broad, deep defect level (DL) red-emission in the range 600 to 750 nm and a sharp ZnSe near-band-edge blue-emission (ZS-NBE) between 445 to 465 nm. While DL and CdSe near-band-edge (CS-NBE) emissions significantly shift with the size of QD due to strong confinement effect, the ZS-NBE show minimal change in peak position indicating a weak confinement effect. The intensities of ZS-NBE and DL emissions also exhibit a strong dependence on the QD size. A gamut of emission colors is obtained by combining the CS-NBE with the ZS-NBE emission and broad DL emission in (Cd,Zn)Se system. Interestingly, we find the convergence of Commission Internationale de l'Eclairage (CIE) coordinates towards the white light with increasing Zn concentration in CdSe. We demonstrate by combining these three emissions in a proper weight ratio WLE can be achieved. Cd1-yZnySe (y = 0. 5; QD size ˜4.9 nm) alloy with a maximum quantum yield of 57% exhibits CIE coordinates of (0.39, 0.4), color rendering index (CRI) of 82, correlated color temperature (CCT) of 3922 K, and Duv of 0.0078 which is very promising for white light applications.

Graphene oxide-TiO2 composite solid phase extraction combined with graphite furnace atomic absorption spectrometry for the speciation of inorganic selenium in water samples.

PubMed

Zhang, Yanan; Chen, Beibei; Wu, Shaowei; He, Man; Hu, Bin

2016-07-01

In this paper, a method of graphene oxide (GO)-TiO2 composite solid phase extraction followed by graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the speciation of inorganic selenium in environmental waters. The adsorption behavior of inorganic Se(IV) and Se(VI) on the GO-TiO2(1:1) composite was investigated. It was found that Se(IV) was quantitatively retained on the GO-TiO2 composites within a wide pH range of 0.5-10, while Se(VI) was quantitatively adsorbed on GO-TiO2(1:1) composite at pH 0.5-2, and no obvious adsorption of Se(VI) within the pH range of 4-10 was found. By selecting pH 6.0, Se(IV) could be easily determined. After reduction of Se(VI), total Se was determined by the proposed method, and Se(VI) was calculated as the difference between the total Se and Se(IV). The factors affecting the separation/preconcentration of Se(IV) and Se(VI) were studied. Under the optimum conditions, the isothermal adsorption of Se(IV) on the GO-TiO2(1:1) composite fitted Langmuir model; a linear range over 0.1-12ngmL(-1) was obtained. The limit of detection (LOD) and precision of the method for Se(IV) was 0.04ngmL(-1) and 9.4% (cSe(IV)=0.5ngmL(-1), n=7), respectively. In order to verify the accuracy of the method, a standard water sample (GSBZ50031-94) was analyzed, and the determined value was in a good agreement to the certified value. The established method was applied to inorganic Se speciation in environmental water samples and the recovery of 87.4-102% was obtained for the spiked samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA.

PubMed

Mills, Taylor J; Mast, M Alisa; Thomas, Judith; Keith, Gabrielle

2016-10-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (<0.5μgL(-1)) to 4070μgL(-1), and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted. Published by Elsevier B.V.

Selenium bioavailability of infant milk diets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghib, H.; Chan, W.Y.; Rennert, O.M.

1986-03-01

The effects of age, types of milk diet and chemical forms of SE on its bioavailability were studied using suckling rats as a model. Human milk, bovine milk and infant formula (regular Similac) extrinsically labeled with either (/sup 75/Se) selenite or (/sup 75/Se) selenomethionine were fed by gastric intubation to 8, 10, 15 and 20 (or 30)-day-old rats. Retention of /sup 75/Se in gut free carcass and liver was measured 3 hours after feeding. At any given age the corresponding absorption of /sup 75/Se from the 3 diets was similar except at 15 days of age when significantly more (/supmore » 75/Se) selenomethionine was absorbed from human milk (83%) than from bovine milk or formula (72%). Much higher amount of (/sup 75/Se) selenomethionine was absorbed by any age group from the 3 milk diets compared to (/sup 75/Se) selenite. An age related change in both (/sup 75/Se) selenite and (/sup 75/Se) selenomethionine absorption was noticed in all 3 diets. Gut free carcass (/sup 75/Se) selenite absorption was 32% in 8-d-old rats and increased to 46% in 20-d-old rats. The corresponding liver /sup 75/Se retention was 7.5 and 19.5%. On the other hand, (/sup 75/Se) selenomethionine retention by the gut free carcass decreased with age from an average of 83% in 8-d-old rats to 72% in 20-d-old rats. The corresponding /sup 75/Se incorporation into the liver increased from 15.5% in 8-d-old rats to 21.9% in 20-d-old rats. It is concluded that twice as much /sup 75/Se) selenite and an age related change in /sup 75/Se absorption was noticed between the 2 chemical forms of Se and between human milk and the other 2 milk diets.« less

Fullerene-like MoSe2 nanoparticles-embedded CNT balls with excellent structural stability for highly reversible sodium-ion storage

NASA Astrophysics Data System (ADS)

Choi, Seung Ho; Kang, Yun Chan

2016-02-01

Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls.Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07733h

Incomplete Hippocampal Inversion: A Comprehensive MRI Study of Over 2000 Subjects.

PubMed

Cury, Claire; Toro, Roberto; Cohen, Fanny; Fischer, Clara; Mhaya, Amel; Samper-González, Jorge; Hasboun, Dominique; Mangin, Jean-François; Banaschewski, Tobias; Bokde, Arun L W; Bromberg, Uli; Buechel, Christian; Cattrell, Anna; Conrod, Patricia; Flor, Herta; Gallinat, Juergen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Ittermann, Bernd; Lemaitre, Hervé; Martinot, Jean-Luc; Nees, Frauke; Paillère Martinot, Marie-Laure; Orfanos, Dimitri P; Paus, Tomas; Poustka, Luise; Smolka, Michael N; Walter, Henrik; Whelan, Robert; Frouin, Vincent; Schumann, Gunter; Glaunès, Joan A; Colliot, Olivier

2015-01-01

The incomplete-hippocampal-inversion (IHI), also known as malrotation, is an atypical anatomical pattern of the hippocampus, which has been reported in healthy subjects in different studies. However, extensive characterization of IHI in a large sample has not yet been performed. Furthermore, it is unclear whether IHI are restricted to the medial-temporal lobe or are associated with more extensive anatomical changes. Here, we studied the characteristics of IHI in a community-based sample of 2008 subjects of the IMAGEN database and their association with extra-hippocampal anatomical variations. The presence of IHI was assessed on T1-weighted anatomical magnetic resonance imaging (MRI) using visual criteria. We assessed the association of IHI with other anatomical changes throughout the brain using automatic morphometry of cortical sulci. We found that IHI were much more frequent in the left hippocampus (left: 17%, right: 6%, χ(2)-test, p < 10(-28)). Compared to subjects without IHI, subjects with IHI displayed morphological changes in several sulci located mainly in the limbic lobe. Our results demonstrate that IHI are a common left-sided phenomenon in normal subjects and that they are associated with morphological changes outside the medial temporal lobe.

Incomplete Hippocampal Inversion: A Comprehensive MRI Study of Over 2000 Subjects

PubMed Central

Cury, Claire; Toro, Roberto; Cohen, Fanny; Fischer, Clara; Mhaya, Amel; Samper-González, Jorge; Hasboun, Dominique; Mangin, Jean-François; Banaschewski, Tobias; Bokde, Arun L. W.; Bromberg, Uli; Buechel, Christian; Cattrell, Anna; Conrod, Patricia; Flor, Herta; Gallinat, Juergen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Ittermann, Bernd; Lemaitre, Hervé; Martinot, Jean-Luc; Nees, Frauke; Paillère Martinot, Marie-Laure; Orfanos, Dimitri P.; Paus, Tomas; Poustka, Luise; Smolka, Michael N.; Walter, Henrik; Whelan, Robert; Frouin, Vincent; Schumann, Gunter; Glaunès, Joan A.; Colliot, Olivier

2015-01-01

The incomplete-hippocampal-inversion (IHI), also known as malrotation, is an atypical anatomical pattern of the hippocampus, which has been reported in healthy subjects in different studies. However, extensive characterization of IHI in a large sample has not yet been performed. Furthermore, it is unclear whether IHI are restricted to the medial-temporal lobe or are associated with more extensive anatomical changes. Here, we studied the characteristics of IHI in a community-based sample of 2008 subjects of the IMAGEN database and their association with extra-hippocampal anatomical variations. The presence of IHI was assessed on T1-weighted anatomical magnetic resonance imaging (MRI) using visual criteria. We assessed the association of IHI with other anatomical changes throughout the brain using automatic morphometry of cortical sulci. We found that IHI were much more frequent in the left hippocampus (left: 17%, right: 6%, χ2−test, p < 10−28). Compared to subjects without IHI, subjects with IHI displayed morphological changes in several sulci located mainly in the limbic lobe. Our results demonstrate that IHI are a common left-sided phenomenon in normal subjects and that they are associated with morphological changes outside the medial temporal lobe. PMID:26733822

High-pressure study of the structural and elastic properties of defect-chalcopyrite HgGa2Se4

NASA Astrophysics Data System (ADS)

Gomis, O.; Vilaplana, R.; Manjón, F. J.; Santamaría-Pérez, D.; Errandonea, D.; Pérez-González, E.; López-Solano, J.; Rodríguez-Hernández, P.; Muñoz, A.; Tiginyanu, I. M.; Ursaki, V. V.

2013-02-01

In this work, we focus on the study of the structural and elastic properties of mercury digallium selenide (HgGa2Se4) which belongs to the family of AB2X4 ordered-vacancy compounds with tetragonal defect chalcopyrite structure. We have carried out high-pressure x-ray diffraction measurements up to 13.2 GPa. Our measurements have been complemented and compared with total-energy ab initio calculations. The equation of state and the axial compressibilities for the low-pressure phase of HgGa2Se4 have been experimentally and theoretically determined and compared to other related ordered-vacancy compounds. The theoretical cation-anion and vacancy-anion distances in HgGa2Se4 have been determined. The internal distance compressibility in HgGa2Se4 has been compared with those that occur in binary HgSe and ɛ-GaSe compounds. It has been found that the Hg-Se and Ga-Se bonds behave in a similar way in the three compounds. It has also been found that bulk compressibility of the compounds decreases following the sequence "ɛ-GaSe > HgGa2Se4 > HgSe." Finally, we have studied the pressure dependence of the theoretical elastic constants and elastic moduli of HgGa2Se4. Our calculations report that the low-pressure phase of HgGa2Se4 becomes mechanically unstable above 13.3 GPa.

Wide emission-tunable CdTeSe/ZnSe/ZnS core–shell quantum dots and their conjugation with E. coli O-157

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Haifeng; Zhou, Guangjun, E-mail: gjzhou@sdu.edu.cn; Zhou, Juan

2015-05-15

Highlights: • QDs with variety morphology were obtained via an injection controlled process. • 3-D PL spectra of core–shell QDs show different excitation wavelength dependence. • The PL intensity of QDs with ZnSe transition layer increases dramatically. • Core–shell QDs were processed into aqueous phase and conjugated with E. coli O-157. - Abstract: Wide emission-tunable and different morphological alloyed CdTeSe quantum dots (QDs), CdTeSe/ZnS and CdTeSe/ZnSe/ZnS core–shell QDs were successfully synthesized via an injection controlled process. The effect of injection procedure and reaction temperature were systematically discussed and the growth mechanism was proposed. Most efficient PL wavelength was correlated withmore » reaction time and temperature. The 3-D PL spectra of spherical bare CdTeSe and core–shell QDs with different passivation showed different excitation wavelength dependency. The PL intensity of CdTeSe/ZnSe/ZnS core–shell QDs increased greatly in comparison with that of CdTeSe and CdTeSe/ZnSe QDs. ZnSe transition layer played an important role in improving the PL intensity by providing a smoothened interface and gradient band offsets. The core–shell QDs were transferred into aqueous phase and successfully conjugated with Escherichia coli O-157. The proposed phase-transfer and bio-labeling strategy may be applicable to various QDs with different compositions.« less

Daily intake of selenium and concentrations in blood of residents of Riyadh City, Saudi Arabia.

PubMed

Al-Othman, Abdulaziz M; Al-Othman, Zeid A; El-Desoky, Gaber E; Aboul-Soud, Mourad A M; Habila, Mohamed A; Giesy, John P

2012-08-01

Concentrations of selenium (Se) in food from local markets of Riyadh, Kingdom of Saudi Arabia (KSA) were measured and daily intake calculated based on information from a questionnaire of foods eaten by healthy Saudis. The daily intake of Se was then compared to concentrations of Se in blood serum. Primary sources of Se in the diet of Saudis were as follows: meat and meat products (31%), egg (20.4%), cereals and cereal products (16%), legumes (8.7%), fruits (6.8%), milk and dairy products (2.0%), beverages (2%), sweets (1.8%), pickles (0.2%), and oil (0.02%). Daily intake of Se, estimated to be 93 μg Se/person/day, was slightly greater than that calculated from the Food and Agriculture Organization (FAO) food balance sheet for KSA, which was approximately 90 μg Se/person/day. The daily intake of Se by Saudis in Riyadh was greater than that of Australians or Dutch but less that of Canadians and Americans. There was a statistically significant correlation (R = +0.38, P < 0.05) between daily intake of Se and concentrations of Se in blood serum of Saudis in Riyadh. The mean concentration of Se in serum was 1.0 × 10(2) ± 30.5 μg Se/l. Taken together, the results suggest that the average Se intake and Se serum concentrations are within the known limits and recommendations, making it unlikely that Saudis are on average at risk of deficiency or toxicity.

Natural variation of selenium in Brazil nuts and soils from the Amazon region.

PubMed

Silva Junior, E C; Wadt, L H O; Silva, K E; Lima, R M B; Batista, K D; Guedes, M C; Carvalho, G S; Carvalho, T S; Reis, A R; Lopes, G; Guilherme, L R G

2017-12-01

Brazil nut tree (Bertholletia excelsa) is native of the Amazon rainforest. Brazil nuts are consumed worldwide and are known as the richest food source of selenium (Se). Yet, the reasoning for such Se contents is not well stablished. We evaluated the variation in Se concentration of Brazil nuts from Brazilian Amazon basin, as well as soil properties, including total Se concentration, of the soils sampled directly underneath the trees crown, aiming to investigate which soil properties influence Se accumulation in the nuts. The median Se concentration in Brazil nuts varied from 2.07 mg kg - 1 (in Mato Grosso state) to 68.15 mg kg - 1 (in Amazonas state). Therefore, depending on its origin, a single Brazil nut could provide from 11% (in the Mato Grosso state) up to 288% (in the Amazonas state) of the daily Se requirement for an adult man (70 μg). The total Se concentration in the soil also varied considerably, ranging from <65.76 to 625.91 μg kg - 1 , with highest Se concentrations being observed in soil samples from the state of Amazonas. Se accumulation in Brazil nuts generally increased in soils with higher total Se content, but decreased under acidic conditions in the soil. This indicates that, besides total soil Se concentration, soil acidity plays a major role in Se uptake by Brazil nut trees, possibly due to the importance of this soil property to Se retention in the soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of supranutritional maternal and colostral selenium supplementation on passive absorption of immunoglobulin G in selenium-replete dairy calves.

PubMed

Hall, Jean A; Bobe, Gerd; Vorachek, William R; Estill, Charles T; Mosher, Wayne D; Pirelli, Gene J; Gamroth, Mike

2014-07-01

Selenium (Se) is an essential micronutrient for ruminant animals affecting both performance and immune functions. Adding 3 mg of Se/L (in the form of Na selenite) to colostrum has been shown to improve IgG absorption in Se-deficient newborn dairy calves. The objective of our study was to determine the effect of supranutritional maternal and colostral Se supplementation on IgG status of Se-replete dairy calves. The study design was a 2 × 2 × 2 factorial design. During the last 8 wk before calving, dairy cows at a commercial dairy were fed either 0 (control cows) or 105 mg of Se-yeast once weekly (supranutritional Se-yeast-supplemented cows), in addition to Na selenite at 0.3 mg of Se/kg of DM in their ration. After birth, calves were fed pooled colostrum from control or supranutritional Se-yeast-supplemented cows to which 0 or 3 mg of Se/L (in the form of Na selenite) was added. Concentrations of whole-blood (WB) Se and serum Se measured at birth and at 48 h and 14 d of age, and serum IgG concentrations measured at 48 h and 14 and 60 d of age were determined. Calves born to Se-yeast-supplemented cows had higher WB-Se and serum-Se concentrations for the first 2 wk, and higher IgG absorption efficiency (62% at 48 h), resulting in higher serum-IgG concentrations (43% at 48 h and 65% at 14 d) and higher total serum-IgG content (50% at 48 h and 75% at 14 d), compared with calves born to control cows. Calves that received colostrum with added Na selenite had higher WB-Se concentrations for the first 2 wk, but only at 14 d of age were serum-Se concentrations, serum-IgG concentrations (53% higher), and total serum-IgG content (56% higher) higher, compared with calves that were fed colostrum without added Na selenite. Calves born to Se-yeast-supplemented cows that received colostrum from Se-yeast cows without added Na selenite had a higher IgG absorption efficiency compared with all other treatment groups. Our results support that feeding cows supranutritional Se-yeast supplement during the dry period or spiking colostrum with Na selenite both improve IgG status of Se-replete calves. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Bioaccessibility of selenium, selenomethionine and selenocysteine from foods and influence of heat processing on the same.

PubMed

Khanam, Anjum; Platel, Kalpana

2016-03-01

Selenium (Se) is an essential nutrient with diverse physiological functions. The selenium content of commonly consumed cereals, pulses and green leafy vegetables (GLV) was determined. Bioaccessibility of Se, and its organic forms selenomethionine (SeMet), and selenocysteine (SeCys2) was also examined, and the effect of heat processing on the same was studied. The bioaccessibility of Se in cereals ranged from 10% to 24%, that of pulses was between 12% and 29%, and of GLV, 10-31%. The concentration of SeMet in the dialysates of the cereals, pulses and GLV ranged from 5.15 to 28.7, 2.7 to 36.2, and 0.03 to 5ngg(-1), respectively. The concentration of SeCys2 in the dialysates of the foods examined was negligible. Heat processing significantly decreased the bioaccessibility of Se, SeMet and SeCys2. This is the first report on the bioaccessibility of Se and its major organic forms from commonly consumed staples, and the effect of heat processing on the same. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extending the spectral range of CdSe/ZnSe quantum wells by strain engineering

NASA Astrophysics Data System (ADS)

Finke, A.; Ruth, M.; Scholz, S.; Ludwig, A.; Wieck, A. D.; Reuter, D.; Pawlis, A.

2015-01-01

We demonstrate efficient room-temperature photoluminescence and spectral tuning of epitaxially grown ZnSe/CdSe quantum well structures almost over the whole visible spectrum (470-600 nm wavelength). The key element to achieve the observed high quantum efficiency and enormous tuning range was the implementation of a special strain engineering technique, which allows us to suppress substantial lattice relaxation of CdSe on ZnSe. Previous studies indicated that a CdSe coverage exceeding 3 ML on ZnSe results in the formation of extensive lattice defects and complete quenching of the photoluminescence at low and room temperature. In contrast, our approach of strain engineering enables the deposition of planar CdSe quantum wells with a thickness ranging from 1 to 6 ML with excellent optical properties. We attribute the observed experimental features to a controllable strain compensation effect that is present in an alternating system of tensile and compressively strained epitaxial layers and supported this model by calculations of the transition energies of the ZnSe/CdSe quantum wells.

The behavior of dissolved inorganic selenium in the Changjiang Estuary

NASA Astrophysics Data System (ADS)

Chang, Yan; Zhang, Jing; Qu, Jianguo; Zhang, Guosen; Zhang, Anyu; Zhang, Ruifeng

2016-02-01

To investigate the behavior of inorganic selenium species in the Changjiang Estuary, samples were taken during summer (July 2011) and winter (March 2012). Dissolved inorganic selenium (DISe) concentrations averaged 1.79 nmol/L in summer and 1.24 nmol/L in winter; the average selenite [Se(IV)] to selenate [Se(VI)] ratio [Se(IV)/Se(VI)] was 0.42 in summer and 0.61 in winter. The data show that Se(IV) and Se(VI) concentrations in the estuary behaved strictly conservatively during winter but non-conservatively during summer due to adsorption by suspended particulate matter (SPM) and assimilation by phytoplankton. In addition, the Se concentration distributions in the Changjiang Estuary were controlled by three water masses, each with a specific Se(IV)/Se(VI) ratio "signature": the Changjiang Water input, the Taiwan Warm Current, and the Yellow Sea Coastal Current. The Se(IV) concentrations were related to the nitrate, silicate, and phosphate concentrations in the estuary. The DISe and Se(IV) concentrations were comparable to those found in other coastal regions and estuaries, which were considered to be natural levels.

Structural and electronic properties of ultrathin FeSe films grown on Bi2Se3(0 0 0 1) studied by STM/STS

NASA Astrophysics Data System (ADS)

Singh, Udai Raj; Warmuth, Jonas; Markmann, Verena; Wiebe, Jens; Wiesendanger, Roland

2017-01-01

We report scanning tunnelling microscopy and spectroscopy (STM/STS) studies on one and two unit cell (UC) high FeSe thin films grown on Bi2Se3(0 0 0 1). In our thin films, we find the tetragonal phase of FeSe and dumb-bell shaped defects oriented along Se-Se bond directions. In addition, we observe striped moiré patterns with a periodicity of (7.3  ±  0.1) nm generated by the mismatch between the FeSe lattice and the Bi2Se3 lattice. We could not find any signature of a superconducting gap in the tunneling spectra measured on the surface of one and two UC thick islands of FeSe down to 6.5 K. The spectra rather show an asymmetric behavior across and a finite density of states at the Fermi level (E F) resembling those taken in the normal state of bulk FeSe.

Structural control of In2Se3 polycrystalline thin films by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Okamoto, T.; Nakada, Y.; Aoki, T.; Takaba, Y.; Yamada, A.; Konagai, M.

2006-09-01

Structural control of In2Se3 polycrystalline thin films was attempted by molecular beam epitaxy (MBE) technique. In2Se3 polycrystalline films were obtained on glass substrates at substrate temperatures above 400 °C. VI/III ratio greatly affected crystal structure of In2Se3 polycrystalline films. Mixtures of -In2Se3 and γ-In2Se3 were obtained at VI/III ratios greater than 20, and layered InSe polycrystalline films were formed at VI/III ratios below 1. γ-In2Se3 polycrystalline thin films without α-phase were successfully deposited with VI/III ratios in a range of 2 to 4. Photocurrent spectra of the γ-In2Se3 polycrystalline films showed an abrupt increase at approximately 1.9 eV, which almost corresponds with the reported bandgap of γ-In2Se3. Dark conductivity and photoconductivity measured under solar simulator light (AM 1.5, 100 mW/cm2) were approximately 10-9 and 10-5 S/cm in the γ-In2Se3 polycrystalline thin films, respectively.

Socioeconomic and regional differences in active transportation in Brazil.

PubMed

Sá, Thiago Hérick de; Pereira, Rafael Henrique Moraes; Duran, Ana Clara; Monteiro, Carlos Augusto

2016-06-27

To present national estimates regarding walking or cycling for commuting in Brazil and in 10 metropolitan regions. By using data from the Health section of 2008's Pesquisa Nacional por Amostra de Domicílio (Brazil's National Household Sample Survey), we estimated how often employed people walk or cycle to work, disaggregating our results by sex, age range, education level, household monthly income per capita, urban or rural address, metropolitan regions, and macro-regions in Brazil. Furthermore, we estimated the distribution of this same frequency according to quintiles of household monthly income per capita in each metropolitan region of the country. A third of the employed men and women walk or cycle from home to work in Brazil. For both sexes, this share decreases as income and education levels rise, and it is higher among younger individuals, especially among those living in rural areas and in the Northeast region of the country. Depending on the metropolitan region, the practice of active transportation is two to five times more frequent among low-income individuals than among high-income individuals. Walking or cycling to work in Brazil is most frequent among low-income individuals and the ones living in less economically developed areas. Active transportation evaluation in Brazil provides important information for public health and urban mobility policy-making. Apresentar estimativas nacionais sobre o deslocamento a pé ou de bicicleta no trajeto casa-trabalho no Brasil e em 10 de suas regiões metropolitanas. Utilizando dados do Suplemento sobre Saúde da Pesquisa Nacional por Amostra de Domicílios de 2008, estimamos a frequência de pessoas empregadas que se deslocam a pé ou de bicicleta no trajeto casa-trabalho estratificada por sexo, e segundo faixa etária, escolaridade, renda domiciliar per capita, residência em área urbana ou rural, regiões metropolitanas e macrorregiões do país. Adicionalmente, estimamos a distribuição da mesma frequência segundo quintos da distribuição da renda domiciliar per capita em cada região metropolitana. Um terço dos homens e mulheres empregados desloca-se a pé ou de bicicleta de casa para o trabalho no Brasil. Em ambos os sexos, esta proporção diminui com o aumento da renda e da escolaridade e é maior entre os mais jovens, entre os que residem em área rural e naqueles residentes na região Nordeste. A depender da região metropolitana, a prática de deslocamento ativo entre os mais pobres é de duas a cinco vezes maior do que entre os mais ricos. O deslocamento a pé ou de bicicleta para o trabalho no Brasil é mais frequente entre os mais pobres e entre pessoas que vivem em áreas e regiões economicamente menos desenvolvidas. A avaliação do deslocamento ativo no País traz informações importantes para a discussão de políticas públicas de mobilidade.

Biochemical polymorphisms in Spanish Avileña-Negra Iberica cattle.

PubMed

Arranz, J J; Bayón, Y; Medjugorac, I; Primitivo, F

1994-01-12

Thirteen biochemical blood polymorphisms were analysed in a population of 149 Spanish Avileña-Negra Ibérica cattle. The study revealed variation at the following nine loci: HBB, CA, NP, CP, AMY1, ALB, GC, TF and PTF2. The following systems were monomorphic: CAT, DIA1, MDH1 and ME1. Using polyacrylamide-gel electrophoresis, a slow, migrating pair of bands was found in the GC protein system. This pattern is probably controlled by the GC(C) allele, described in only a few cases in cattle. Furthermore, starch-gel electrophoresis allowed the detection of a variant with intermediate mobility between the ALB(A) and the ALB(B) alleles at the albumin locus. A variant with a similar electrophoretic pattern has occasionally been reported in cattle. However, utilizing IEF under denaturing conditions, such a variant could not be differentiated from the ALB(A) allele and thus its significance is not clear. ZUSAMMENFASSUNG: Biochemischer Polymorphismus in spanischen Avileña-Negra Iberica Rindern Insgesamt 13 biochemische Systeme wurden in einer Population von 149 spanischen Avilena-Negra-Iberika-Rindern hinsichtlich Polymorphismus analysiert. Es zeigten sich Varianten bei folgenden Loci: HBB, CA, NP, CP, AMY1, ANB, GC, TF und BTF2, während CAT, DEA, MDH1 und ME1 monomorph sind. Bei stärke Gel-Elektrophorese wurde im Albumin-Locus eine Variante mit intermediärer Mobilität zwischen ALB(A) und ÄLB(B) Allel entdeckt. Eine solche Variante wurde bisher nur sehr selten bei Rindern beobachtet. Darüber hinaus wurde bei Polyacrylamid-Gel-Elektrophorese ein langsam wanderndes Paar von Bändern im GC-Proteinsystem gefunden. Dieses Muster ist wahrscheinlich von dem selten vorkommenden GC(C) -Allel verursacht. RESUMEN: Se analizaron trece polimorfismos bioquímicos sanguíneos en una población de 149 animales de la raza Avileña-Negra Ibérica de ganado vacuno. El estudio reveló la existencia de variación en los nueve loci siguientes: HBB, CA, NP, CP, AMY1, ALB, GC, TF y PTF2. Fueron monomórficos los sistemas siguientes: CAT, DIA1, MDH1 y ME1. Utilizando eletroforesis en gel de poliacrilamida se encontró un par de bandas de migración lenta en el sistema de la proteína GC. Este patrón probablemente está controlado por el infrecuente alelo GC(C) , descrito en unos pocos casos en el ganado vacuno. Además, la electroforesis en gel de almidón permitió detectar en el locus de la albúmina una banda con movilidad intermedia entre los alelos ALB(A) y ALB(B) . Una variante con un patrón electroforético similar ha sido descrita en muy pocas ocasiones en el ganado vacuno. Sin embargo, la utilización de IEF en condiciones desnaturalizantes no permitió diferenciar esta variante del alelo ALB(A) y, por lo tanto, el significado de la misma no está claro. 1994 Blackwell Verlag GmbH.

Distribution of toenail selenium levels in young adult Caucasians and African Americans in the United States: The CARDIA Trace Element Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xun, Pengcheng; Bujnowski, Deborah; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC

Background: Data on selenium (Se) levels in American young adults, especially in African Americans, are lacking. Objective: This study presented toenail Se distributions in American young adults of both genders, including both Caucasians and African Americans; and explored potential predictors of toenail Se levels. Data and methods: Data from the Coronary Artery Risk Development in Young Adults study among 4252 American young adults, aged 20-32 in 1987 was used to examine toenail Se levels by instrumental neutron-activation analysis. The distribution of Se levels was described and multivariable linear regression was used to examine potential modifiers of toenail Se concentration withinmore » ethnicity-gender subgroups. Results: The geometric mean of toenail Se in this cohort was 0.844 {mu}g/g (95% CI, 0.840-0.849 {mu}g/g) and the median was 0.837 {mu}g/g (95% CI, 0.833-0.844 {mu}g/g). Median levels from lowest to highest quintile were 0.691, 0.774, 0.838, 0.913 and 1.037 {mu}g/g. Se levels varied geographically, and were generally in accordance with its concentrations in local soil. Males, African Americans, current smokers, heavy drinkers and less educated participants were more likely to have low Se levels. Conclusion: This study suggests that toenail Se levels vary geographically depending on soil Se concentrations. In addition to gender, ethnicity and education level, smoking status and alcohol consumption are two important indicators of Se status since they are modifiable lifestyle factors. Findings from this study might aid public health professionals in identifying people at relatively high or low Se levels, so that chronic disease prevention efforts can be directed toward these subgroups. - Research highlights: {yields} Average of toenail Se levels in this cohort was 0.844 {mu}g/g (95% CI, 0.840-0.849 {mu}g/g). {yields} Toenail Se levels vary geographically depending on soil Se concentrations. {yields} Males, African Americans and less educated participants have low Se levels. {yields} Smoking status and alcohol consumption are two important indicators of Se status.« less

[Effect of selenium deficiency on the F344 inbred line offspring rats' neuro-behavior, ability of learning and memory].

PubMed

Hong, Liang-Li; Tian, Dong-Ping; Su, Min; Shen, Xiu-Na; Gao, Yuxia

2006-01-01

To establish the selenium (Se) deficient animal model on F344 inbred line rats and observe the effects of a long-term Se-deficiency on the offspring's neuro-behavior, abilities of learning and memory. Feeding F344 inbred line rats on Se-deficient diet to establish Se-deficient animal model. For the offspring, the body weight, physiological indexes nervous reflections for growth and development were monitored during the early postnatal period. The Se-deficient diet contained less than 0.01 mg/kg and the glutathione peroxidase (GSH-Px) activity in blood of the Se-deficient group rats is lower than the Se-normal group after feeding on Se-deficient diet for 4 weeks. For the offspring, the birth weight and the body weight of Se-deficient group were obviously lower than the Se-normal group before weaning. Se-deficient offspring rats differed from Se-normal controls in lower scores in surface righting reflex (RR) test at postnatal 4th day after delivery, cliff avoidance test at postnatal 7th day and auditory acuity trial at postnatal 10th day respectively. But these differences disappear after a few days in the same tests. In addition, no significant differences between two groups in suspending test and walking ability test at postnatal 12th and 14th day. In open field test, Se-deficient male offspring stayed less time in the middle grid and moved less. In Morris water maze test, the Se-deficient offspring spent more time to find the hidden platform at the 6th and 9th training tests in the place navigation trial. Furthermore, the Se-deficient group spent less time in target quadrant when giving the spatial probe trial. A Se-deficient animal model have been established on F344 inbred line rats successfully. A long-term Se deficiency could retard the development of the offspring in uterus and after delivery. Se deficiency also decreased the offspring's abilities of spatial learning and memory in Morris water maze test and resulted in the male offspring's nervousness to new stimulant.

Prostatic Response to Supranutritional Selenium Supplementation: Comparison of the Target Tissue Potency of Selenomethionine vs. Selenium-Yeast on Markers of Prostatic Homeostasis

PubMed Central

Waters, David J.; Shen, Shuren; Kengeri, Seema S.; Chiang, Emily C.; Combs, Gerald F.; Morris, J. Steven; Bostwick, David G.

2012-01-01

Prostate cancer is the product of dysregulated homeostasis within the aging prostate. Supplementation with selenium in the form of selenized yeast (Se-yeast) significantly reduced prostate cancer incidence in the Nutritional Prevention of Cancer Trial. Conversely, the Selenium and Vitamin E Cancer Prevention Trial (SELECT) showed no such cancer-protective advantage using selenomethionine (SeMet). The possibility that SeMet and Se-yeast are not equipotent in promoting homeostasis and cancer risk reduction in the aging prostate has not been adequately investigated; no direct comparison has ever been reported in man or animals. Here, we analyzed data on prostatic responses to SeMet or Se-yeast from a controlled feeding trial of 49 elderly beagle dogs—the only non-human species to frequently develop prostate cancer during aging—randomized to one of five groups: control; low-dose SeMet, low-dose Se-yeast (3 μg/kg); high-dose SeMet, high-dose Se-yeast (6 μg/kg). After seven months of supplementation, we found no significant selenium form-dependent differences in toenail or intraprostatic selenium concentration. Next, we determined whether SeMet or Se-yeast acts with different potency on six markers of prostatic homeostasis that likely contribute to prostate cancer risk reduction—intraprostatic dihydrotestosterone (DHT), testosterone (T), DHT:T, and epithelial cell DNA damage, proliferation, and apoptosis. By analyzing dogs supplemented with SeMet or Se-yeast that achieved equivalent intraprostatic selenium concentration after supplementation, we showed no significant differences in potency of either selenium form on any of the six parameters over three different ranges of target tissue selenium concentration. Our findings, which represent the first direct comparison of SeMet and Se-yeast on a suite of readouts in the aging prostate that reflect flux through multiple gene networks, do not further support the notion that the null results of SELECT are attributable to differences in prostatic consequences achievable through daily supplementation with SeMet, rather than Se-yeast. PMID:23201838

Organic and inorganic selenium: IV. passive transfer of immunoglobulin from ewe to lamb.

PubMed

Stewart, W C; Bobe, G; Vorachek, W R; Stang, B V; Pirelli, G J; Mosher, W D; Hall, J A

2013-04-01

Newborn lambs depend on their dams for passive transfer of immunoglobulins, primarily IgG, for protection from harmful pathogens until their own immunological defenses have developed. Previous studies have suggested that supplementation with Se results in a modest increase in IgG concentration in serum of newborn calves and lambs. To evaluate the effect of the Se source and supplementation rate in ewes during pregnancy on passive transfer of IgG to their lambs, 210 Polypay, Suffolk, or Suffolk × Polypay cross ewes were divided into 7 treatment groups (n = 30 each) and drenched weekly with no Se, at the maximum FDA-allowed concentration with inorganic Na-selenite or organic Se-yeast (4.9 mg Se/wk), or with inorganic Na-selenite and organic Se-yeast at supranutritional concentrations (14.7 and 24.5 mg Se/wk). Ewe serum IgG concentrations were measured within 30 d of parturition, ewe colostrum and lamb serum IgG concentrations were measured at parturition before suckling, and lamb serum IgG concentrations were measured again at 48 h postnatal. Ewes receiving 24.5 mg Se/wk tended to have or had, independent of Se source, greater colostral IgG concentrations than ewes receiving 4.9 mg Se/wk overall (81.3 vs. 66.2 mg/mL; P = 0.08) and for Polypay ewes only (90.1 vs. 60.7 mg/mL; P = 0.03). Polypay ewes receiving Se-yeast at 24.5 mg Se/wk transferred a greater calculated total IgG amount to their lambs than Polypay ewes receiving Se-yeast at 4.9 mg Se/wk (15.5 vs. 11.6 g; P = 0.02), whereas the converse was true (interaction between Se source and dose concentration; P = 0.03) for Polypay ewes receiving inorganic Na-selenite at 24.5 mg Se/wk vs. Na-selenite at 4.9 mg/wk (11.6 vs. 15.7 g; P = 0.08). Our results suggest that supranutritional Se supplementation of Polypay ewes during pregnancy increases colostral IgG concentrations but that the optimal supplementation rate for IgG transfer from ewe to lamb may differ for Na-selenite and Se-yeast.

Dietary antioxidants and the biochemical response to oxidant inhalation. II. Influence of dietary selenium on the biochemical effects of ozone exposure in mouse lung

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elsayed, N.M.; Hacker, A.D.; Kuehn, K.

The influence of dietary selenium (Se) on the pulmonary biochemical response to ozone (O/sub 3/) exposure was examined. For 11 weeks, weanling female strain A/St mice were fed a test diet containing Se either at 0 ppm (-Se) or 1 ppm (+Se). Each diet contained 55 ppm vitamin E (vit E). Mice from each dietary group were exposed to 0.8 +/- 0.05 ppm (1568 +/- 98 micrograms/m3) O/sub 3/ continuously for 5 days. After O/sub 3/ exposure, they were killed along with a matched number of unexposed controls, and their lungs were analyzed for various biochemical parameters. The Se contentsmore » of lung tissue and whole blood were determined, and the levels were seven- to eightfold higher in +Se mice than in -Se mice, reflecting the Se intake of the animals. In unexposed control mice, Se deficiency caused a decline in glutathione peroxidase (GP) activity relative to +Se group. After O/sub 3/ exposure, the GP activity in the -Se group was associated with a lack of stimulation of glutathione reductase (GR) activity and the pentose phosphate cycle (PPC) as assessed by measuring glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) activities. In contrast, the +Se group after O/sub 3/ exposure exhibited increases in all four enzyme activities. Other parameters, e.g., lung weight, total lung protein, DNA and nonprotein sulfhydryl contents, and O/sub 2/ consumption, were not affected by dietary Se in the presence or absence of O/sub 3/ exposure. The data indicate that dietary Se alters the GP activity, which in turn influences the GR and PPC activities in the lung evidently through a reduced demand for NADPH. The level of vit E in the lung was found to be twofold higher in the -Se group than in the +Se group, suggesting a compensatory relationship between Se and vit E in the lung. With O3 exposure, both Se and vit E contents further increased in the lungs of each dietary group.« less

Biokinetic food chain modeling of waterborne selenium pulses into aquatic food chains: Implications for water quality criteria.

PubMed

DeForest, David K; Pargee, Suzanne; Claytor, Carrie; Canton, Steven P; Brix, Kevin V

2016-04-01

We evaluated the use of biokinetic models to predict selenium (Se) bioaccumulation into model food chains after short-term pulses of selenate or selenite into water. Both periphyton- and phytoplankton-based food chains were modeled, with Se trophically transferred to invertebrates and then to fish. Whole-body fish Se concentrations were predicted based on 1) the background waterborne Se concentration, 2) the magnitude of the Se pulse, and 3) the duration of the Se pulse. The models were used to evaluate whether the US Environmental Protection Agency's (USEPA's) existing acute Se criteria and their recently proposed intermittent Se criteria would be protective of a whole-body fish Se tissue-based criterion of 8.1 μg g(-1) dry wt. Based on a background waterborne Se concentration of 1 μg L(-1) and pulse durations of 1 d and 4 d, the Se pulse concentrations predicted to result in a whole-body fish Se concentration of 8.1 μg g(-1) dry wt in the most conservative model food chains were 144 and 35 μg L(-1), respectively, for selenate and 57 and 16 μg L(-1), respectively, for selenite. These concentrations fall within the range of various acute Se criteria recommended by the USEPA based on direct waterborne toxicity, suggesting that these criteria may not always be protective against bioaccumulation-based toxicity that could occur after short-term pulses. Regarding the USEPA's draft intermittent Se criteria, the biokinetic modeling indicates that they may be overly protective for selenate pulses but potentially underprotective for selenite pulses. Predictions of whole-body fish Se concentrations were highly dependent on whether the food chain was periphyton- or phytoplankton-based, because the latter had much greater Se uptake rate constants. Overall, biokinetic modeling provides an approach for developing acute Se criteria that are protective against bioaccumulation-based toxicity after trophic transfer, and it is also a useful tool for evaluating averaging periods for chronic Se criteria. © 2015 SETAC.

First-principles study of defect formation in a photovoltaic semiconductor Cu2ZnGeSe4

NASA Astrophysics Data System (ADS)

Nishihara, Hironori; Maeda, Tsuyoshi; Wada, Takahiro

2018-02-01

The formation energies of neutral Cu, Zn, Ge, and Se vacancies in kesterite-type Cu2ZnGeSe4 were evaluated by first-principles pseudopotential calculations using plane-wave basis functions. The calculations were performed at typical points in Cu-(Zn1/2Ge1/2)-Se and Cu3Se2-ZnSe-GeSe2 pseudoternary phase diagrams for Cu2ZnGeSe4. The results were compared with those for Cu2ZnSnSe4, Cu2ZnGeS4, and Cu2ZnSnS4 calculated using the same version of the CASTEP program code. The results indicate that Cu vacancies are easily formed in Cu2ZnGeSe4 under the Cu-poor condition as in the above compounds and CuInSe2, suggesting that Cu2ZnGeSe4 is also a preferable p-type absorber material for thin-film solar cells. The formation energies of possible antisite defects, such as CuZn and CuGe, and of possible complex defects, such as CuZn+ZnCu, were also calculated and compared within the above materials. The antisite defect of CuZn, which has the smallest formation energy within the possible defects, is concluded to be the most hardly formed in Cu2ZnGeSe4 among the compounds.

The effect of defect emissions on enhancement photocatalytic performance of ZnSe QDs and ZnSe/rGO nanocomposites

NASA Astrophysics Data System (ADS)

Yousefi, Ramin; Azimi, H. R.; Mahmoudian, M. R.; Basirun, Wan Jeffrey

2018-03-01

A systematic study about the origin of defects emission of ZnSe structure was conducted by photoluminescence (PL) spectrometer at room temperature. It was observed that different intermediate energy levels in band-gap space of ZnSe structure were generated by different defects such as Se-, Zn-vacancies, Se-, Zn-interstitials, and surface states. Effects of these defects on the photocatalytic performance of ZnSe quantum dots (QDs) and ZnSe/graphene nanocomposites were investigated. The pristine ZnSe QDs and ZnSe/graphene nanocomposites were synthesized by a co-precipitation method. The PL spectra of the samples showed four emissions from four regions of the visible spectrum such as violet, green, orange, and red emissions. The violet emission was associated with the near-band-edge (NBE) of the ZnSe nanostructures, while, the other emissions were related to different defects of ZnSe structures. Annealing the samples in the H2 atmosphere caused to increase orange emission intensity and indicated that origin of orange emission was a donor-acceptor pair (DAPs) related to singly positively charged Se-vacancies (VSe) to singly negatively charged zinc vacancy (VZn-). Photocatalytic study of the samples to remove the methylene blue (MB) dye showed that the photocatalytic performance of the samples improved by graphene as an additive and increasing the orange emission intensity.

Facile synthesis of hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure for high performance photodetectors.

PubMed

Chen, Shuo; Qiao, Xvsheng; Wang, Fengxia; Luo, Qun; Zhang, Xianghua; Wan, Xia; Xu, Yang; Fan, Xianping

2016-01-28

An effective colloidal process involving the hot-injection method is developed to synthesize uniform single-crystalline Sb2Se3 nanorods in high yields. The photoconductive characteristics of the as-synthesized Sb2Se3 nanorods are investigated by developing a film-based photodetector and this device displays a remarkable response to visible light with an "ON/OFF" ratio as high as 50 (with an incident light density of 12.05 mW cm(-2)), short response/recovery times and long-term durability. To overcome the challenge of the intrinsic low electrical conductivity of Sb2Se3, hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure having a type-II band alignment are firstly prepared. The electric current of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film has been significantly increased both in the dark and under light illumination. The responsivity of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film is about 4.2 times as much as that of the photodetector based on the Sb2Se3 nanorod film. This improvement can be considered as an important step to promote Sb2Se3 based semiconductors for applications in high performance photodetectors.

Developmental and Persistent Toxicities of Maternally Deposited Selenomethionine in Zebrafish (Danio rerio).

PubMed

Thomas, Jith K; Janz, David M

2015-08-18

The objectives of this study were (1) to establish egg selenium (Se) toxicity thresholds for mortality and deformities in early life stages of zebrafish (Danio rerio) after exposure to excess selenomethionine (SeMet, the dominant chemical species of Se in diets) via in ovo maternal transfer and (2) to investigate the persistent effects of developmental exposure to excess SeMet on swim performance and metabolic capacities in F1-generation adult zebrafish. Adult zebrafish were fed either control food (1.3 μg Se/g, dry mass or d.m.) or food spiked with increasing measured concentrations of Se (3.4, 9.8, or 27.5 μg Se/g, d.m.) in the form of SeMet for 90 d. In ovo exposure to SeMet increased mortality and deformities in larval zebrafish in a concentration-dependent fashion with threshold egg Se concentrations (EC10s) of 7.5 and 7.0 μg Se/g d.m., respectively. Impaired swim performance and greater respiration and metabolic rates were observed in F1-generation zebrafish exposed in ovo to 6.8 and 12.7 μg Se/g d.m and raised to adulthood in clean water. A species sensitivity distribution (SSD) based on egg Se developmental toxicity thresholds suggests that zebrafish are the most sensitive fish species studied to date.

Understanding reduced inorganic mercury accumulation in rice following selenium application: Selenium application routes, speciation and doses.

PubMed

Tang, Wenli; Dang, Fei; Evans, Douglas; Zhong, Huan; Xiao, Lin

2017-02-01

Selenium (Se) has recently been demonstrated to reduce inorganic mercury (IHg) accumulation in rice plants, while its mechanism is far from clear. Here, we aimed at exploring the potential effects of Se application routes (soil or foliar application with Se), speciation (selenite and selenate), and doses on IHg-Se antagonistic interactions in soil-rice systems. Results of our pot experiments indicated that soil application but not foliar application could evidently reduce tissue IHg concentrations (root: 0-48%, straw: 15-58%, and brown rice: 26-74%), although both application routes resulted in comparable Se accumulation in aboveground tissues. Meanwhile, IHg distribution in root generally increased with amended Se doses in soil, suggesting antagonistic interactions between IHg and Se in root. These results provided initial evidence that IHg-Se interactions in the rhizosphere (i.e., soil or rice root), instead of those in the aboveground tissues, could probably be more responsible for the reduced IHg bioaccumulation following Se application. Furthermore, Se dose rather than Se speciation was found to be more important in controlling IHg accumulation in rice. Our findings regarding the importance of IHg-Se interactions in the rhizosphere, together with the systematic investigation of key factors affecting IHg-Se antagonism and IHg bioaccumulation, advance our understanding of Hg dynamics in soil-rice systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bioaccumulation of selenium from coal fly ash and associated environmental hazards in a freshwater fish community

DOE Office of Scientific and Technical Information (OSTI.GOV)

Besser, J.; Giesy, J.; Brown, R.

1995-12-31

Bioaccumulation of Se by fish from Pigeon River and Pigeon Lake, Michigan, which receive inputs of Se from a coal fly-ash disposal facility, was studied to assess potential hazards of Se toxicity to fish and wildlife. Se concentrations in fish from sites receiving Se inputs from fly ash disposal ponds were significantly greater than concentrations in fish from upstream sites, which were near normal background concentrations. Se bioaccumulation differed substantially among fish species, especially in the most contaminated site, where whole-body Se concentrations for the five species analyzed ranged from 1.4 to 3.8 {micro}g/g (wet wt.). The top predator inmore » the community, northern pike (Esox lucius), had Se concentrations less than those in likely prey species. Among lower-order consumers, Se concentrations were greater in limnetic species (spottail shiner, Notropis hudsonius, and yellow perch, Perca flavescens), than in benthic species (white sucker, Catostomus commersoni, and rock bass, Ambloplites rupestris). Se concentrations in tissues of fish from the lower Pigeon River and Pigeon Lake approached, but did not exceed lowest observable effect concentrations (LOAECs) for Se in tissues of sensitive fish species. However, Se concentrations in several fish species exceeded LOAECs for dietary Se exposure of sensitive species of birds and mammals, suggesting that consumption of fish in these areas may pose a hazard to piscivorous wildlife.« less

Toenail selenium as an indicator of environmental exposure: A cross-sectional study.

PubMed

Filippini, Tommaso; Ferrari, Angela; Michalke, Bernhard; Grill, Peter; Vescovi, Luciano; Salvia, Chiara; Malagoli, Carlotta; Malavolti, Marcella; Sieri, Sabina; Krogh, Vittorio; Bargellini, Annalisa; Martino, Antonio; Ferrante, Margherita; Vinceti, Marco

2017-05-01

The relation between toxicity and essentiality of selenium (Se) is of growing interest in human health, as the effects may widely differ depending of its different chemical species and the exposure levels. Toenail Se has been proposed as a reliable biomarker of long-term Se exposure, but few studies investigated the correlation between its toenail content and environmental determinants (i.e., dietary food intake). We aimed to determine the relation of toenail Se levels with serum Se species as well as food items. We recruited a random sample of Modena (Northern Italy) municipal residents, from whom we collected detailed personal information, dietary habits, toenail specimen for Se determination and a blood sample for serum Se speciation analysis. Toenail Se mean value was 0.96 µg/g (range, 0.47‑1.60), with slightly higher levels in females, in non-obese subjects and in Se supplements users, while it was lower in current smokers. Toenail Se positively correlated with organic Se forms, mainly selenoprotein P and selenocysteine, and inversely with the inorganic forms (selenite and selenate). Toenail Se was not associated with meat, cereals and dairy products consumption, positively correlated with fruit and slightly with vegetable intake, and negatively with fish and seafood consumption. Finally, no clear association emerged with estimated air Se exposure.

Plasma levels of selenium-containing proteins in Inuit adults from Nunavik.

PubMed

Achouba, Adel; Dumas, Pierre; Ouellet, Nathalie; Lemire, Mélanie; Ayotte, Pierre

2016-11-01

Selenium (Se) is highly abundant in marine foods traditionally consumed by Inuit of Nunavik (Northern Quebec, Canada) and accordingly, their Se intake is among the highest in the world. However, little is known regarding the biological implications of this high Se status in this Arctic indigenous population. We used a method combining affinity chromatography and inductively coupled plasma-mass spectrometry with quantification by post-column isotope dilution to determine total Se levels and concentrations of Se-containing proteins in archived plasma samples of Inuit adults who participated to the 2004 Nunavik Inuit Health Survey (N = 852). Amounts of mercury (Hg) associated with Se-containing proteins were also quantified. Results show that glutathione peroxidase 3 (GPx3), selenoprotein P (SelP) and selenoalbumin (SeAlb) represented respectively 25%, 52% and 23% of total plasma Se concentrations. In addition, small amounts of Hg co-eluted with each Se-containing protein and up to 50% of plasma Hg was associated to SelP. Total plasma Se concentrations (median = 139 μg L− 1; interquartile range (IQR) = 22.7 μg L− 1) were markedly lower and less variable than whole blood Se concentration (median = 261 μg L− 1, IQR = 166 μg L− 1). A non linear relation was observed between whole blood Se and plasma Se levels, with plasma Se concentrations leveling off at approximately 200 μg L− 1, whereas 16% and 3% of individuals exhibited whole blood concentrations higher than 500 μg L− 1 and 1000 μg L− 1, respectively. In contrast, a linear relationship was previously reported in communities consuming Brazil nuts which are rich Se, mainly present as selenomethionine. This suggests that a different selenocompound, possibly selenoneine, is present in the Arctic marine food chain and accumulates in the blood cellular fraction of Inuit.

Involvement of a Broccoli COQ5 Methyltransferase in the Production of Volatile Selenium Compounds[C][OA

PubMed Central

Zhou, Xin; Yuan, Youxi; Yang, Yong; Rutzke, Michael; Thannhauser, Theodore W.; Kochian, Leon V.; Li, Li

2009-01-01

Selenium (Se) is an essential micronutrient for animals and humans but becomes toxic at high dosage. Biologically based Se volatilization, which converts Se into volatile compounds, provides an important means for cleanup of Se-polluted environments. To identify novel genes whose products are involved in Se volatilization from plants, a broccoli (Brassica oleracea var italica) cDNA encoding COQ5 methyltransferase (BoCOQ5-2) in the ubiquinone biosynthetic pathway was isolated. Its function was authenticated by complementing a yeast coq5 mutant and by detecting increased cellular ubiquinone levels in the BoCOQ5-2-transformed bacteria. BoCOQ5-2 was found to promote Se volatilization in both bacteria and transgenic Arabidopsis (Arabidopsis thaliana) plants. Bacteria expressing BoCOQ5-2 produced an over 160-fold increase in volatile Se compounds when they were exposed to selenate. Consequently, the BoCOQ5-2-transformed bacteria had dramatically enhanced tolerance to selenate and a reduced level of Se accumulation. Transgenic Arabidopsis expressing BoCOQ5-2 volatilized three times more Se than the vector-only control plants when treated with selenite and exhibited an increased tolerance to Se. In addition, the BoCOQ5-2 transgenic plants suppressed the generation of reactive oxygen species induced by selenite. BoCOQ5-2 represents, to our knowledge, the first plant enzyme that is not known to be directly involved in sulfur/Se metabolism yet was found to mediate Se volatilization. This discovery opens up new prospects regarding our understanding of the complete metabolism of Se and may lead to ways to modify Se-accumulator plants with increased efficiency for phytoremediation of Se-contaminated environments. PMID:19656903

Biomagnification of mercury and selenium in two lakes in southern Norway.

PubMed

Økelsrud, Asle; Lydersen, Espen; Fjeld, Eirik

2016-10-01

We have investigated bioaccumulation and trophic transfer of both mercury (Hg) and selenium (Se) in two lakes in southern Norway to reveal a suggested mitigating effect of Se on Hg biota accumulation. The study included analysis of total Se (Se), total Hg (Hg), and methyl-mercury (MeHg) in water, littoral and pelagic invertebrates and perch (Perca fluviatilis), together with stable isotope analysis (δ(15)N and δ(13)C) in biota. Mean dissolved Se ranged from 22 to 59ngL(-1), while Hg and MeHg in lake water ranged from 1 to 3ngL(-1) and 0.01 to 0.06ngL(-1). Biota Se and Hg concentrations (dry weight) ranged from 0.41mgSekg(-1) and 0.06mgHgkg(-1) in primary littoral invertebrates and up to 2.9mg Sekg(-1) and 3.6mgHgkg(-1) in perch. Both Hg and Se biomagnified in the food web, with a trophic magnification factor (TMF) of 4.64 for Hg and 1.29 for Se. The reported positive transfer of Se in the food web, despite the low measured dissolved Se, suggest that a major proportion of the Se in these lakes are both highly bioavailable and bioaccumulative. However, we did not find support for a Se-facilitated inhibition in the accumulation of Hg in perch, as Se and Hg concentrations in perch muscle correlated positively and Se did not explain any variations in Hg after we controlled for the effects of other important covariates. We postulate that this may be a result of insufficient concentrations of dissolved Se and subsequently in biota in our studied lakes for an efficient Hg sequestration up the food web. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Selenium Supplementation Restores Innate and Humoral Immune Responses in Footrot-Affected Sheep

PubMed Central

Hall, Jean A.; Vorachek, William R.; Stewart, Whitney C.; Gorman, M. Elena; Mosher, Wayne D.; Pirelli, Gene J.; Bobe, Gerd

2013-01-01

Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source (organic Se-yeast, inorganic Na-selenite or Na-selenate) and Se-dosage (1, 3, 5 times FDA-permitted level) on FR severity, 120 ewes with and 120 ewes without FR were drenched weekly for 62 weeks with different Se sources and dosages (30 ewes/treatment group). Innate immunity was evaluated after 62 weeks of supplementation by measuring neutrophil bacterial killing ability. Adaptive immune function was evaluated by immunizing sheep with keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. At baseline, FR-affected ewes had lower whole-blood and serum-Se concentrations; this difference was not observed after Se supplementation. Se supplementation increased neutrophil bacterial killing percentages in FR-affected sheep to percentages observed in supplemented and non-supplemented healthy sheep. Similarly, Se supplementation increased KLH antibody titers in FR-affected sheep to titers observed in healthy sheep. FR-affected sheep demonstrated suppressed cell-mediated immunity at 24 hours after intradermal KLH challenge, although there was no improvement with Se supplementation. We did not consistently prevent nor improve recovery from FR over the 62 week Se-treatment period. In conclusion, Se supplementation does not prevent FR, but does restore innate and humoral immune functions negatively affected by FR. PMID:24340044

Biomimetic synthesis of selenium nanospheres by bacterial strain JS-11 and its role as a biosensor for nanotoxicity assessment: a novel se-bioassay.

PubMed

Dwivedi, Sourabh; Alkhedhairy, Abdulaziz A; Ahamed, Maqusood; Musarrat, Javed

2013-01-01

Selenium nanoparticles (Se-NPs) were synthesized by green technology using the bacterial isolate Pseudomonas aeruginosa strain JS-11. The bacteria exhibited significant tolerance to selenite (SeO3(2-)) up to 100 mM concentration with an EC50 value of 140 mM. The spent medium (culture supernatant) contains the potential of reducing soluble and colorless SeO3(2-) to insoluble red elemental selenium (Se(0)) at 37°C. Characterization of red Se° product by use of UV-Vis spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) with energy dispersive X-ray spectrum (EDX) analysis revealed the presence of stable, predominantly monodispersed and spherical selenium nanoparticles (Se-NPs) of an average size of 21 nm. Most likely, the metabolite phenazine-1-carboxylic acid (PCA) released by strain JS-11 in culture supernatant along with the known redox agents like NADH and NADH dependent reductases are responsible for biomimetic reduction of SeO3(2-) to Se° nanospheres. Based on the bioreduction of a colorless solution of SeO3(2-) to elemental red Se(0), a high throughput colorimetric bioassay (Se-Assay) was developed for parallel detection and quantification of nanoparticles (NPs) cytotoxicity in a 96 well format. Thus, it has been concluded that the reducing power of the culture supernatant of strain JS-11 could be effectively exploited for developing a simple and environmental friendly method of Se-NPs synthesis. The results elucidated that the red colored Se° nanospheres may serve as a biosensor for nanotoxicity assessment, contemplating the inhibition of SeO3(2-) bioreduction process in NPs treated bacterial cell culture supernatant, as a toxicity end point.

Chemical Kinetic and Molecular Genetic Study of Selenium Oxyanion Reduction by Enterobactor cloacae SLD1a-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma,J.; Kobayashi, D.; Yee, N.

2007-01-01

Microbial processes play an important role in the redox transformations of toxic selenium oxyanions. In this study, we employed chemical kinetic and molecular genetic techniques to investigate the mechanisms of Se(IV) and Se(VI) reduction by the facultative anaerobe Enterobacter cloacae SLD1a-1. The rates of microbial selenium oxyanion reduction were measured as a function of initial selenium oxyanion concentration (0-1.0 mM) and temperature (10-40 C), and mutagenesis studies were performed to identify the genes involved in the selenium oxyanion reduction pathway. The results indicate that Se(IV) reduction is significantly more rapid than the reduction of Se(VI). The kinetics of the reductionmore » reactions were successfully quantified using the Michaelis-Menten kinetic equation. Both the rates of Se(VI) and Se(IV) reduction displayed strong temperature-dependence with Ea values of 121 and 71.2 kJ/mol, respectively. X-ray absorption near-edge spectra collected for the precipitates formed by Se(VI) and Se(IV) reduction confirmed the formation of Se(0). A miniTn5 transposon mutant of E. cloacae SLD1a-1 was isolated that had lost the ability to reduce Se(VI) but was not affected in Se(IV) reduction activity. Nucleotide sequence analysis revealed the transposon was inserted within a tatC gene, which encodes for a central protein in the twin arginine translocation system. Complementation by the wild-type tatC sequence restored the ability of mutant strains to reduce Se(VI). The results suggest that Se(VI) reduction activity is dependent on enzyme export across the cytoplasmic membrane and that reduction of Se(VI) and Se(IV) are catalyzed by different enzymatic systems.« less

Differences in the responses of three plasma selenium-containing proteins in relation to methylmercury-exposure through consumption of fish/whales.

PubMed

Ser, Ping Han; Omi, Sanae; Shimizu-Furusawa, Hana; Yasutake, Akira; Sakamoto, Mineshi; Hachiya, Noriyuki; Konishi, Shoko; Nakamura, Masaaki; Watanabe, Chiho

2017-02-05

Putative protective effects of selenium (Se) against methylmercury (MeHg) toxicity have been examined but no conclusion has been reached. We recently reported the lack of serious neurological symptoms in a Japanese fish-eating population with high intakes of MeHg and suggested a potential protective role for Se. Here, relationships between levels of Hg and Se in the blood and plasma samples, with a quantitative evaluation of Se-containing proteins, obtained from this population were examined. While levels of the whole-blood Hg (WB-Hg) and plasma Se (P-Se) showed a positive correlation, stratified analysis revealed that they correlated only in samples with higher (greater than the median) levels of MeHg. A food frequency questionnaire showed that consumption of fish/whales correlated with WB-Hg, but not with P-Se, suggesting that the positive correlation between WB-Hg and P-Se might not be the result of co-intake of these elements from seafood. Speciation of plasma Se revealed the differences in the responses of two plasma selenoproteins, glutathione peroxidase (GPx) and selenoprotein P (SePP), in relation to Hg exposure. In the high-Hg group, SePP showed a positive correlation with WB-Hg, but GPx did not. In the low-Hg group, neither SePP nor GPx showed any correlation with WB-Hg. These observations suggest that the increase in P-Se in the high-Hg group might be associated with an increase in SePP, which may, in turn, suggest an increased demand for one or more selenoproteins in various organs, for which SePP supplies the element. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The selenium isotopic variations in chondrites are mass-dependent; Implications for sulfide formation in the early solar system

NASA Astrophysics Data System (ADS)

Labidi, J.; König, S.; Kurzawa, T.; Yierpan, A.; Schoenberg, R.

2018-01-01

Element transfer from the solar nebular gas to solids occurred either through direct condensation or via heterogeneous reactions between gaseous molecules and previously condensed solid matter. The precursors of altered sulfides observed in chondrites are for example attributed to reactions between gaseous hydrogen sulfide and metallic iron grains. The transfer of selenium to solids likely occurred through a similar pathway, allowing the formation of iron selenides concomitantly with sulfides. The formation rate of sulfide however remains difficult to assess. Here we investigate whether the Se isotopic composition of meteorites contributes to constrain sulfide formation during condensation stages of our solar system. We present high precision Se concentration and δ 82 / 78 Se data for 23 chondrites as well as the first δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se data for a sub-set of seven chondrites. We combine our dataset with previously published sulfur isotopic data and discuss aspects of sulfide formation for various types of chondrites. Our Se concentration data are within uncertainty to literature values and are consistent with sulfides being the dominant selenium host in chondrites. Our overall average δ 82 / 78 Se value for chondrites is - 0.21 ± 0.43 ‰ (n = 23, 2 s.d.), or - 0.14 ± 0.21 ‰ after exclusion of three weathered chondrites (n = 20, 2 s.d.). These average values are within uncertainty indistinguishable from a previously published estimate. For the first time however, we resolve distinct δ 82 / 78 Se between ordinary (- 0.14 ± 0.07 ‰, n = 9, 2 s.d.), enstatite (- 0.27 ± 0.05 ‰, n = 3, 2 s.d.) and CI carbonaceous chondrites (- 0.01 ± 0.06 ‰, n = 2, 2 s.d.). We also resolve a Se isotopic variability among CM carbonaceous chondrites. In addition, we report on δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se values determined for 7 chondrites. Our data allow evaluating the mass dependency of the δ 82 / 78 Se variations. Mass-independent deficits ro excesses of 74Se, 76Se and 77Se are calculated relative to the observed 82Se/78Se ratios, and were observed negligible. This rules out poor mixing of nucleosynthetic components to account for the δ 82 / 78 Se variability and implies that the mass dependent Se isotopic variations were produced in a once-homogeneous disk. The mass-dependent isotopic difference between enstatite and ordinary chondrites may reflect the contribution of a kinetic sulfidation process at anomalously high H2S-H2Se contents in the region of enstatite chondrite formation. Experimental studies showed that high H2S contents favor the formation of compact sulfide layers around metallic grains. This decreases the reactive surface, which tends to inhibit the continuation of the sulfidation reaction. Under these conditions sulfide growth likely occurs under isotopic disequilibrium and favors the trapping of light S and Se isotopes in solids; This hypothesis provides an explanation for our Se isotope as well as for previously published S isotope data. On the other hand, high δ 82 / 78 Se values in carbonaceous chondrites may result from sample heterogeneities generated by parent body aqueous alteration, or could reflect the contribution of ices carrying photo-processed Se from the outer solar system.

Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Jing; Liang Jingjing; Pan Yingli

Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en){sub 2}(dien)({eta}{sup 2}-SbSe{sub 4})] (Ln=Ce(1a), Nd(1b)), [Ln(en){sub 2}(dien)(SbSe{sub 4})] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)({mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4})]{sub {infinity}} (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)({eta}{sup 2}-SbSe{sub 4})] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe{sub 4}]{sup 3-} acts as a monodentate ligand mono-SbSe{sub 4}, a bidentate chelating ligand {eta}{sup 2}-SbSe{sub 4} or a tridentate bridging ligand {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} to the lanthanide(III) center depending on themore » Ln{sup 3+} ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with E{sub g} between 2.08 and 2.51 eV. - Graphical Abstract: Two structural types of lanthanide(III) selenidoantimonates are formed in both en-dien and en-trien mixed polyamines across lanthanide series, indicating the lanthanide contraction effect on the structures of the lanthanide(III) selenidoantimonates. Highlights: > Two structural types of lanthanide selenidoantimonates are prepared across the lanthanide series in both Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) systems. > The [SbSe{sub 4}]{sup 3-} anion acts as a mono-SbSe{sub 4}, a {eta}{sup 2}-SbSe{sub 4} or a {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} ligand to the Ln{sup 3+} ions. > The soft base ligand [SbSe{sub 4}]{sup 3-} can be controlled to coordinate to the Ln{sup 3+} ions with en+dien and en+trien as co-ligands.« less

Physiological adaptation of maternal plasma volume during pregnancy: a systematic review and meta-analysis.

PubMed

de Haas, S; Ghossein-Doha, C; van Kuijk, S M J; van Drongelen, J; Spaanderman, M E A

2017-02-01

To describe the physiological pattern of gestational plasma volume adjustments in normal singleton pregnancy and compare this with the pattern in pregnancies complicated by pregnancy-induced hypertension, pre-eclampsia or fetal growth restriction. We performed a meta-analysis of the current literature on plasma volume adjustments during physiological and complicated pregnancies. Literature was retrieved from PubMed (NCBI) and EMBASE (Ovid) databases. Included studies reported both reference plasma volume measurements (non-pregnant, prepregnancy or postpartum) and measurements obtained during predetermined gestational ages. Mean differences bet ween the reference and pregnancy plasma volume measurements were calculated for predefined intervals of gestational age using a random-effects model described by DerSimonian and Laird. Thirty studies were included in the meta-analysis with publication dates ranging from 1934 to 2007. Plasma volume increased in the first weeks of pregnancy, with the steepest increase occurring during the second trimester. Plasma volume continued to increase in the third trimester with a pooled maximum increase of 1.13 L (95% CI, 1.07-1.19 L), an increase of 45.6% (95% CI, 43.0-48.1%) in physiological pregnancies compared with the reference value. The plasma volume expansion in gestational hypertensive and growth-restricted pregnancies was 0.80 L (95% CI, 0.59-1.02 L), an increase of 32.3% (95% CI, 23.6-41.1%) in the third trimester, a smaller increase than in physiological pregnancies (P < 0.0001). During physiological pregnancy, plasma volume increases by, on average, more than 1 L as compared with non-pregnant conditions. In pregnancies complicated by pregnancy-induced hypertension, pre-eclampsia or fetal growth restriction, plasma volume increase in the third trimester is 13.3% lower than in normal pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Adaptación fisiológica del volumen del plasma materno durante el embarazo: una revisi\\xF3n sistemática y metaanálisis RESUMEN OBJETIVO: Describir el patrón fisiológico de los cambios en el volumen del plasma gestacional en embarazos normales con feto único y compararlo con el patrón en los embarazos complicados por hipertensión gestacional, preeclampsia o restricción del crecimiento fetal. MÉTODOS: Se realizó un metaanálisis de la literatura actual sobre los cambios en el volumen de plasma durante embarazos complicados y fisiológicos. La literatura se obtuvo de las bases de datos PubMed (NCBI) y EMBASE (Ovid). Los estudios incluidos mencionaban tanto mediciones de referencia del volumen plasmático (no embarazada, antes del embarazo o después del parto) como mediciones tomadas a edades gestacionales predeterminadas. Se calcularon las medias de las diferencias entre las mediciones de referencia y las del embarazo para el volumen plasmático a intervalos predefinidos de la edad gestacional, utilizando un modelo de efectos aleatorios descrito por DerSimonian y Laird. En el metaanálisis se incluyeron treinta estudios con fechas de publicación entre 1934 y 2007. El volumen plasmático aumentó en las primeras semanas de embarazo y el mayor incremento se produjo durante el segundo trimestre. El volumen de plasma continuó aumentando en el tercer trimestre con un aumento combinado máximo de 1,13L (IC 95%, 1,7-1,19 L), lo que supone un aumento del 45,6% (IC 95%, 43,0-48,1%) en embarazos fisiológicas en comparación con el valor de referencia. El aumento del volumen plasmático en los embarazos con hipertensión y con crecimiento intrauterino restringido fue de 0,80L (IC 95%, 0,59-1,02 L), lo que supone un aumento del 32,3% (IC 95%, 23,6-41,1%) en el tercer trimestre, y un incremento menor que en los embarazos fisiológicos (P <0,0001). Durante el embarazo fisiológico el volumen de plasma aumenta, en promedio, más de 1L, en comparación con el de las no embarazadas. En los embarazos complicados por hipertensión gestacional, preeclampsia o restricción del crecimiento fetal, el aumento del volumen plasmático en el tercer trimestre es un 13,3% menor que en el embarazo normal. :meta : ,、。 : meta。PubMed(NCBI)EMBASE(Ovid)。(、)。DerSimonianLaird,。 : Meta30,19342007。,。,1.13 L(95% CI,1.07~1.19 L),,45.6%(95% CI,43.0%~48.1%)。0.80 L(95%CI,0.59~1.02 L),32.3%(95% CI,23.6%~41.1%),(P<0.0001)。 : ,,1 L。、,13.3%。. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

An Overview of Selenium Uptake, Metabolism, and Toxicity in Plants

PubMed Central

Gupta, Meetu; Gupta, Shikha

2017-01-01

Selenium (Se) is an essential micronutrient for humans and animals, but lead to toxicity when taken in excessive amounts. Plants are the main source of dietary Se, but essentiality of Se for plants is still controversial. However, Se at low doses protects the plants from variety of abiotic stresses such as cold, drought, desiccation, and metal stress. In animals, Se acts as an antioxidant and helps in reproduction, immune responses, thyroid hormone metabolism. Selenium is chemically similar to sulfur, hence taken up inside the plants via sulfur transporters present inside root plasma membrane, metabolized via sulfur assimilatory pathway, and volatilized into atmosphere. Selenium induced oxidative stress, distorted protein structure and function, are the main causes of Se toxicity in plants at high doses. Plants can play vital role in overcoming Se deficiency and Se toxicity in different regions of the world, hence, detailed mechanism of Se metabolism inside the plants is necessary for designing effective Se phytoremediation and biofortification strategies. PMID:28123395

Impact of selenium supply on Se-methylselenocysteine and glucosinolate accumulation in selenium-biofortified Brassica sprouts.

PubMed

Avila, Fabricio William; Yang, Yong; Faquin, Valdemar; Ramos, Silvio Junio; Guilherme, Luiz Roberto G; Thannhauser, Theodore W; Li, Li

2014-12-15

Brassica sprouts are widely marketed as functional foods. Here we examined the effects of Se treatment on the accumulation of anticancer compound Se-methylselenocysteine (SeMSCys) and glucosinolates in Brassica sprouts. Cultivars from the six most extensively consumed Brassica vegetables (broccoli, cauliflower, green cabbage, Chinese cabbage, kale, and Brussels sprouts) were used. We found that Se-biofortified Brassica sprouts all were able to synthesize significant amounts of SeMSCys. Analysis of glucosinolate profiles revealed that each Brassica crop accumulated different types and amounts of glucosinolates. Cauliflower sprouts had high total glucosinolate content. Broccoli sprouts contained high levels of glucoraphanin, a precursor for potent anticancer compound. Although studies have reported an inverse relationship between accumulation of Se and glucosinolates in mature Brassica plants, Se supply generally did not affect glucosinolate accumulation in Brassica sprouts. Thus, Brassica vegetable sprouts can be biofortified with Se for the accumulation of SeMSCys without negative effects on chemopreventive glucosinolate contents. Published by Elsevier Ltd.

Preparation and Enhanced Thermoelectric Performance of Cu2Se-SnSe Composite Materials

NASA Astrophysics Data System (ADS)

Peng, Zhi; He, Danqi; Mu, Xin; Zhou, Hongyu; Li, Cuncheng; Ma, Shifang; Ji, Pengxia; Hou, Weikang; Wei, Ping; Zhu, Wanting; Nie, Xiaolei; Zhao, Wenyu

2018-03-01

A series of p-type xCu2Se-SnSe (x = 0%, 0.10%, 0.15%, 0.20%, and 0.25%) composite thermoelectric materials have been prepared by the combination of ultrasonic dispersion and spark plasma sintering methods. The effects of secondary phase Cu2Se on the phase composition, microstructure, and thermoelectric properties of the composites were investigated. Microstructure characterization and elemental maps indicated Cu2Se grains uniformly distributed on the boundaries of the matrix. Transport measurements demonstrated that enhancement of the power factor and reduction of the thermal conductivity can be realized simultaneously by optimizing the adding content of Cu2Se. The highest ZT value of 0.51 at 773 K was achieved for the sample with x = 0.15%, increased by 24% compared with that of the SnSe matrix. These results demonstrate that optimizing the Cu2Se content can improve the thermoelectric performance of p-type SnSe polycrystalline materials.

A new generation of alloyed/multimetal chalcogenide nanowires by chemical transformation

PubMed Central

Yang, Yuan; Wang, Kai; Liang, Hai-Wei; Liu, Guo-Qiang; Feng, Mei; Xu, Liang; Liu, Jian-Wei; Wang, Jin-Long; Yu, Shu-Hong

2015-01-01

One-dimensional metal chalcogenide nanostructures are important candidates for many technological applications such as photovoltaic and thermoelectric devices. However, the design and synthesis of one-dimensional metal chalcogenide nanostructured materials with controllable components and properties remain a challenge. We report a general chemical transformation process for the synthesis of more than 45 kinds of one-dimensional alloyed/hybrid metal chalcogenide nanostructures inherited from mother template TexSey@Se core-shell nanowires with tunable compositions. As many as nine types of monometal chalcogenide alloy nanowires (including AgSeTe, HgSeTe, CuSeTe, BiSeTe, PbSeTe, CdSeTe, SbSeTe, NiSeTe, and CoSeTe) can be synthesized. Alloyed and hybrid nanowires integrated with two or more alloyed metal chalcogenide phases can also be prepared. The compositions of all of these metal chalcogenide nanowires are tunable within a wide range. This protocol provides a new general route for the controllable synthesis of a new generation of one-dimensional metal chalcogenide nanostructures. PMID:26601137

When one becomes two: Ba12In4Se20, not quite isostructural to Ba12In4S19

NASA Astrophysics Data System (ADS)

Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Yao, Jiyong; Mar, Arthur

2017-09-01

The ternary selenide Ba12In4Se20 was synthesized by reaction of BaSe, In2Se3, and Se at 1023 K. Single-crystal X-ray diffraction revealed a trigonal structure (space group R 3 bar, Z = 6, a = 10.0360(6) Å, c = 78.286(4) Å at room temperature) consisting of one-dimensional stacks of InSe4 tetrahedra, In2Se7 double tetrahedra, selenide Se2- anions, and diselenide Se22- anions, with Ba2+ cations in the intervening spaces. The selenide Ba12In4Se20 can be derived from the corresponding sulfide Ba12In4S19 by replacing one monoatomic Ch2- anion with a diatomic Ch22- anion. An optical band gap of 1.70(2) eV, consistent with the dark red colour of the crystals, was deduced from the UV-vis-NIR diffuse reflectance spectrum.

Preparation and Enhanced Thermoelectric Performance of Cu2Se-SnSe Composite Materials

NASA Astrophysics Data System (ADS)

Peng, Zhi; He, Danqi; Mu, Xin; Zhou, Hongyu; Li, Cuncheng; Ma, Shifang; Ji, Pengxia; Hou, Weikang; Wei, Ping; Zhu, Wanting; Nie, Xiaolei; Zhao, Wenyu

2018-06-01

A series of p-type xCu2Se-SnSe ( x = 0%, 0.10%, 0.15%, 0.20%, and 0.25%) composite thermoelectric materials have been prepared by the combination of ultrasonic dispersion and spark plasma sintering methods. The effects of secondary phase Cu2Se on the phase composition, microstructure, and thermoelectric properties of the composites were investigated. Microstructure characterization and elemental maps indicated Cu2Se grains uniformly distributed on the boundaries of the matrix. Transport measurements demonstrated that enhancement of the power factor and reduction of the thermal conductivity can be realized simultaneously by optimizing the adding content of Cu2Se. The highest ZT value of 0.51 at 773 K was achieved for the sample with x = 0.15%, increased by 24% compared with that of the SnSe matrix. These results demonstrate that optimizing the Cu2Se content can improve the thermoelectric performance of p-type SnSe polycrystalline materials.

[Effects of nano-selenium on the capability of learning memory and the activity of Se-protein of mice].

PubMed

Qin, Fenju; Ye, Yaxin; Yao, Xuemei

2008-07-01

To investigate the effects of Nano-Selenium on learning memory capability and activity of two kinds of Se-protein in brain and liver of mice, Na, SeO3 as the controls. The mice were administred two kinds of origin (doses of 1 microgSe/d, 2 microgSe/d, 4 microgSe/d) Se by intra-gastric injection respectively. The learning memory ability of the mice was measured by Y-type maze test. Activities of glutathione peroxidase (GSH-Px) and iodothyronine deiodinase (ID) in brain and liver were also measured. In comparison with the control groups of Na2 Se03, learning memory abilities were improved and activities of ID and GSH-Px (P < 0.01 or P < 0.05) of brain and liver were increased in Nano-Se treatment groups. Nano-Se could improve learning memory ability of mice, and enhance ID and GSH-Px activities of brain and liver in mice.

Isomorphism and solid solutions among Ag- and Au-selenides

NASA Astrophysics Data System (ADS)

Palyanova, Galina A.; Seryotkin, Yurii V.; Kokh, Konstantin A.; Bakakin, Vladimir V.

2016-09-01

Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag2-xAuxSe with a step of х=0.25 (0≤х≤2) to 1050 °С and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag2Se - Ag1.94Au0.06Se, fischesserite Ag3AuSe2 - Ag3.2Au0.8Se2 and gold selenide AuSe - Au0.94Ag0.06Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe.

LPE growth of crack-free PbSe layers on Si(100) using MBE-Grown PbSe/BaF2CaF2 buffer layers

NASA Astrophysics Data System (ADS)

Strecker, B. N.; McCann, P. J.; Fang, X. M.; Hauenstein, R. J.; O'Steen, M.; Johnson, M. B.

1997-05-01

Crack-free PbSe on (100)-oriented Si has been obtained by a combination of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) techniques. MBE is employed first to grow a PbSe/BaF2/CaF2 buffer structure on the (100)-oriented Si. A 2.5 μm thick PbSe layer is then grown by LPE. The LPE-grown PbSe displays excellent surface morphology and is continuous over the entire 8×8 mm2 area of growth. This result is surprising because of the large mismatch in thermal expansion coefficients between PbSe and Si. Previous attempts to grow crack-free PbSe by MBE alone using similar buffer structures on (100)-oriented Si have been unsuccessful. It is speculated that the large concentration of Se vacancies in the LPE-grown PbSe layer may allow dislocation climb along higher order slip planes, providing strain relaxation.

Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system

NASA Astrophysics Data System (ADS)

Simonelli, L.; Paris, E.; Wakita, T.; Marini, C.; Terashima, K.; Miao, X.; Olszewski, W.; Ramanan, N.; Heinis, D.; Kubozono, Y.; Yokoya, T.; Saini, N. L.

2017-12-01

We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE) of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

The effects of staggered bandgap in the InP/CdSe and CdSe/InP core/shell quantum dots.

PubMed

Kim, Sunghoon; Park, Jaehyun; Kim, Sungwoo; Jung, Won; Sung, Jaeyoung; Kim, Sang-Wook

2010-06-15

New type-II structures of CdSe/InP and InP/CdSe core-shell nanocrystals which have staggered bandgap alignment were fabricated. Using a simple model for the wave function for electrons and holes in InP/CdSe and CdSe/InP core/shell nanocrystals showed the wave function of the electron and hole spread into the shell, respectively. The probability density of the InP/CdSe and CdSe/InP core/shell QDs also showed a similar tendency. As a result, the structure exhibits increased delocalization of electrons and holes, leading to a red-shift in absorption and emission. Quantum yield increased in the InP/CdSe, however decreased in the CdSe/InP. The reason may be due to the surface trap and high activation barrier for de-trapping in the InP shell. 2010 Elsevier Inc. All rights reserved.

Preconcentration and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples with nano-sized TiO2 colloid and determination by HG-AFS.

PubMed

Fu, Jiaqi; Zhang, Xu; Qian, Shahua; Zhang, Lin

2012-05-30

A united method for speciation analysis of Se (IV) and Se (VI) in environmental water samples was developed using nano-sized TiO(2) colloid as adsorbent and hydride generation atomic fluorescence spectrometry (HG-AFS) as determination means. When the pH values of bulk solution were between 6.0 and 7.0, successful adsorption onto 1 mL nano-sized TiO(2) colloid (0.2%) was achieved for more than 97.0% of Se (IV) while Se (VI) barely got adsorbed. Therefore, the method made it possible to preconcentrate and determine Se (IV) and Se (VI) separately. The precipitated TiO(2) with concentrated selenium was directly converted to colloid without desorption. Selenium in the resulting colloid was then determined by HG-AFS. The detection limits (3σ) and relative standard deviations (R.S.D) of this method were 24 ng/L and 42 ng/L, 7.8% (n=6) and 7.0% (n=6) for Se (IV) and Se (VI), respectively. This simple, sensitive, and united method was successfully applied to the separation and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Ab initio phonon thermal transport in monolayer InSe, GaSe, GaS, and alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandey, Tribhuwan; Parker, David S.; Lindsay, Lucas

We compare vibrational properties and phonon thermal conductivities (κ) of monolayer InSe, GaSe and GaS systems using density functional theory and Peierls-Boltzmann transport methods. In going from InSe to GaSe to GaS, system mass decreases giving both increasing acoustic phonon velocities and decreasing scattering of these heat-carrying modes with optic phonons, ultimately giving κInSe< κGaSe< κGaS. This behavior is demonstrated by correlating the scattering phase space limited by fundamental conservation conditions with mode scattering rates and phonon dispersions for each material. We also show that, unlike flat monolayer systems such as graphene, thermal transport is governed by in-plane vibrations inmore » InSe, GaSe and GaS, similar to buckled monolayer materials such as silicene. Alloying of InSe, GaSe and GaS systems provides an effective method for modulating their κ through intrinsic vibrational modifications and phonon scattering from mass disorder giving reductions ~2-3.5 times. This disorder also suppresses phonon mean free paths in the alloy systems compared to those in their crystalline counterparts. This work provides fundamental insights of lattice thermal transport from basic vibrational properties for an interesting set of two-dimensional materials.« less