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Sample records for cai2-based crystals termo

  1. Teoria da estrutura a termo das taxas de juros

    OpenAIRE

    Cox,John C.; Ingersoll Jr.,Jonathan E.; Ross,Stephen A.

    2007-01-01

    Este estudo usa um modelo intertemporal de equilíbrio geral de precificação de ativos para estudar a estrutura a termo das taxas de juros. Nesse modelo, expectativas, aversão ao risco, alternativas de investimento e preferências quanto ao momento do consumo atuam na determinação dos preços. Muitos fatores tradicionalmente mencionados como influentes sobre a estrutura a termo são, assim, incluídos de uma maneira plenamente condizente com o comportamento maximizador e as expectativas racionais....

  2. Sobre termos, proposições e argumentos

    Directory of Open Access Journals (Sweden)

    Jorge de Barros Pires

    Full Text Available RESUMO: O Pragmatismo, como proposto por Charles S. Peirce, deve ser considerado um método para a produção teórica de pensamento que visa à construção de conceitos, a qual assume a forma de uma máxima lógica orientadora da conduta científica. Se um conceito é uma relação sígnica e a sua compreensão, um processo sígnico, encontramos na semiótica peirceana uma estratégia para discriminar as etapas da compreensão conceitual e avaliar os significados de termos e conceitos abstratos. Assim, o objetivo deste trabalho é explicar os princípios lógicos que governam os tipos de Signos que mais diretamente estão relacionados à construção de conceitos, a saber: o Símbolo-Remático, o Símbolo-Dicente e o Argumento. Tais signos correspondem à antiga divisão Termo, Proposição e Argumento, modificada de modo a ser aplicável aos signos em geral.

  3. Estudo evolutivo do comportamento motor em crianças nascidas pré-termo e crianças nascidas a termo

    OpenAIRE

    Eliane da Silva Mewes Gaetan

    1999-01-01

    Resumo: o objetivo deste estudo foi avaliar a evolução do controle postural nos três primeiros meses de vida em crianças nascidas pré-termo e crianças nascidas a termo. Este trabalho de pesquisa foi desenvolvido no Serviço de Fisioterapia do Hospital Universitário Regional do Norte do Paraná, da Universidade Estadual de Londrina, sendo a coleta de dadosrealizadaentre 10dejunho de 1997e 3Ode agostode 1998.O estudofoi do tipo casocontrole, comparando-se 10 crianças nascidas pré-termo com 10 cri...

  4. Compreensão do termo de consentimento informado

    Directory of Open Access Journals (Sweden)

    Maria de Lourdes Pessole Biondo-Simões

    Full Text Available OBJETIVO: O termo de consentimento informado é uma obrigação para o exercício profissional e para a pesquisa envolvendo seres humanos. Representa o respeito à autonomia. Este estudo teve por objetivo reconhecer o grau de entendimento dos indivíduos que participam de uma pesquisa ou de um tratamento. MÉTODOS: Um termo de consentimento foi preparado com linguagem potencialmente clara e acessível, com índice de facilidade de leitura de Flesch igual a 95, o que o classificou como muito fácil. Foram analisados dados como idade, grau de escolaridade, hábito de leitura, meios de acesso à informação e internet e renda familiar, como fatores que modificam o entendimento do consentimento livre e esclarecido. RESULTADOS: Apesar do termo ter sido preparado para atingir pontuação de acerto entre 9 e 10, observou-se que ele atingiu 7,5 ± 1,62 e não esteve relacionado à idade ou ao sexo. O nível de escolaridade influenciou a capacidade de entendimento (p=0,0013, bem como o hábito de leitura (p=0,0001 e o acesso à Internet (p=0,0070. A análise de ganho mostrou que os que ganham mais de dez salários mínimos são os que compreendem melhor (p=0,0041. CONCLUSÃO: Pode-se admitir que os sujeitos para pesquisa devem ser aqueles com melhor nível de escolaridade, com habitualidade para a leitura, com facilidade de acesso à internet e os que têm melhor faixa salarial. Na prática médica, observar a condição de cada um dos doentes, entender as suas limitações de compreensão, ler junto com eles, um à um, explicando todos os pontos.

  5. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  6. Termo technology programme. Final report 1993-1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    The TERMO-technology programme was realised in 1993-1997. The aim of the programme was to promote the profitability and sustainable development of district heating by means of research and development actions. The programme included 36 research projects that were distributed to four research areas. These included heat distribution, metering, information and control systems, the economy of district heating as well as system development. The costs totaled to FIM 12 million. The programme was financed by the participating companies and the Technology Development Centre TEKES. Around eighty Finnish companies and institutions participated in the programme. In addition, the programme participated in international research cooperation in the framework of the Nordic Council of Ministers and the International Energy Agency programmes. The research area Heat Distribution included projects on rehabilitation and status control of district heating networks, pumping, thermal stresses in district heating pipes, material questions, water treatment, steam pipe systems as well as drag reducing additives in district heating water. The research area Metering, Information and Control Systems included projects on forecasts of district heating load, calibration of flow meters, heat cost allocation in buildings, control systems and their qualifications in buildings and improved cooling of district heating water in the consumer equipment. The research area Economy included projects on determination of subscribed heat demand, pricing methods of district heating, success factors of energy companies as well as long term prospects of district heating in Finland. The research area System Development included projects on changing heat loads, district cooling as well as combined heat and power production. After the TERMO programme joint efforts will be continued for the development of district heating technology. The emphasis will be to improve the feasibility of combined heat and power

  7. Termos psicopatológicos em bandas e músicas de rock and roll

    OpenAIRE

    Gios,Thaísa Silva; Lotufo Neto,Francisco

    2013-01-01

    OBJETIVO: Investigar o uso de termos psicopatológicos nos nomes de bandas de rock and roll e em suas músicas. MÉTODO: Termos psicopatológicos do glossário do DSM-IV foram digitados em português e inglês na página do YouTube. Bandas e músicas de rock and roll foram identificadas. O mesmo procedimento foi realizado, a título de comparação, com o glossário de termos neurológicos da CID-10. RESULTADOS: Foram encontrados nomes de bandas ou músicas referentes a 62 termos psiquiátricos e a 24 termos...

  8. Lessons learnt from FARO/TERMOS corium melt quenching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Huhtiniemi, I.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    The influence of melt quantity, melt composition, water depth and initial pressure on quenching is assessed on the basis of seven tests performed in various conditions in the TERMOS vessel of the FARO facility at JRC-Ispra. Tests involved UO{sub 2}-based melt quantities in the range 18-176 kg at a temperature of approximately 3000 K poured into saturated water. The results suggest that erosion of the melt jet column is an efficient contributor to the amount of break-up, and thus quenching, for large pours of corium melt. The presence of Zr metal in the melt induced a much more efficient quenching than in a similar test with no Zr metal, attributed to the oxidation of the Zr. Significant amounts of H{sub 2} were produced also in tests with pure oxidic melts (e.g. about 300 g for 157 kg melt). In the tests at 5.0 and 2.0 MPa good mixing with significant melt break-up and quenching was obtained during the penetration in the water. At 0.5 MPa, good penetration of the melt into the water could still be achieved, but a jump in the vessel pressurisation occurred when the melt contacted the bottom and part (5 kg) of the debris was re-ejected from the water. (author)

  9. TERMOS AMBIENTAIS E SOCIAIS NOS RELATÓRIOS DA ADMINISTRAÇÃO

    Directory of Open Access Journals (Sweden)

    Ilse Maria Beuren

    2012-07-01

    Full Text Available O estudo objetiva verificar a tendência dos termos ambientais e sociais evidenciados nos relatórios da administração de 1997 a 2006 de empresas familiares brasileiras. Realizou-se pesquisa exploratória, com abordagem qualitativa, por meio de pesquisa documental e da técnica de análise de conteúdo nos RA de 1997 a 2006. No universo das 500 maiores empresas listadas na Revista Exame, edição 2006, identificaram-se 21 empresas familiares de capital aberto e de controle acionário brasileiro, mas dessas somente 16 publicaram seu RA nos dez anos considerados. Os resultados mostram que a oscilação na quantidade de páginas dos RA ao longo dos anos apresenta relação com algum evento ocorrido nas empresas. A evidenciação dos termos ambientais está mais relacionada às medidas tomadas para cuidar e preservar o meio ambiente do que aos passivos ambientais. A evidenciação dos termos sociais foi direcionada de maneira equilibrada ao público interno e externo. Conclui-se que há uma tendência nos termos ambientais e sociais evidenciados nos RA de 1997 a 2006 das empresas pesquisadas, ainda que tenham sido incorporados vários termos novos ao longo do período.

  10. Ocorrência de fungos filamentosos termo-resistentes em polpa de tomate envasada assepticamente

    Directory of Open Access Journals (Sweden)

    BAGLIONI Flávio

    1999-01-01

    Full Text Available Este trabalho teve como objetivo principal determinar a ocorrência de fungos filamentosos termo-resistentes durante o processamento asséptico de polpa de tomate (8° BRIX. Durante o período de safra de tomate foram feitas amostragens em 9 lotes (3 no início, 3 no pico e 3 em fim de safra e no período de entresafra em 5 lotes. Foi feita a enumeração de fungos termo-resistentes nas amostras coletadas durante as diferentes etapas do processo asséptico de cada lote. Foram obtidas contagens médias relativamente baixas, variando entre <1 e 8UFC/100mL de amostra. As maiores contagens foram obtidas na matéria prima e na água de pré lavagem e transporte. Cinqüenta linhagens de fungos termo-resistentes detectadas no procedimento de enumeração foram isoladas, codificadas e estocadas. Os esporos de cada isolado com 1 mês de cultivo foram submetidos a diferentes choques térmicos para selecionar a linhagem de fungo mais termo-resistente. O isolado de fungo mais termo-resistente (sobrevivência ao choque à 100° C/25 minutos foi identificado como Neosartorya fischeri.

  11. Auditory evoked potentials in premature and full-term infants Potenciais evocados auditivos em lactentes pré-termo e a termo

    Directory of Open Access Journals (Sweden)

    Maria Angélica de Almeida Porto

    2011-10-01

    Full Text Available Accurate information about type, degree, and configuration of hearing loss are necessary for successful audiological early interventions. Auditory brainstem response with tone burst stimuli (TB ABR and auditory steady-state response (ASSR exams provide this information. AIM: To analyze the clinical applicability of TB ABR and ASSR at 2 kHz in infants, comparing responses in full-term and premature neonates. MATERIAL AND METHOD: The study was cross-sectional, clinical and experimental. Subjects consisted of 17 premature infants and 19 full-term infants. TB ABR and ASSR exams at 2000 Hz were done during natural sleep. RESULTS: The electrophysiological minimum response obtained with TB ABR was 32.4 dBnHL (52.4 dBSPL; the ASSR minimum was 13.8 dBHL (26.4 dBSPL. The exams required 21.1 min and 22 min, respectively. Premature and full-term infant responses showed no statistically significant differences, except for auditory steady-state response duration. CONCLUSIONS: Both exams have clinical applicability at 2 kHz in infants, with 20 min of duration, on average. In general, there are no differences between premature and full-term individuals.O sucesso de uma intervenção audiológica precoce depende de informações precisas quanto ao tipo, grau e configuração da perda auditiva. O potencial evocado auditivo de tronco encefálico com o estímulo tone burst (PEATE TB e a resposta auditiva de estado estável (RAEE proporcionam tais informações. OBJETIVO: Investigar a aplicabilidade clínica, em lactentes, do PEATE TB e da RAEE na frequência de 2 kHz, comparando as respostas dos lactentes nascidos a termo e prétermo. MATERIAL E MÉTODO: O estudo (transversal, clínico e experimental foi realizado com uma casuística de 17 lactentes pré-termo e 19 a termo submetidos ao PEATE TB e RAEE em 2000 Hz. RESULTADOS: A resposta eletrofisiológica mínima obtida com o PEATE TB foi de 32,4 dBnNA (52,4 dBNPS e com a RAEE de 13,8 dBNA (26,4 dBNPS, com dura

  12. Usos de termos do ramo cervejeiro na mídia escrita

    Directory of Open Access Journals (Sweden)

    Márcia Sipavicius Seide

    2011-06-01

    Full Text Available Este artigo apresenta uma análise lexicológica que leva em consideração aspectos sociodiscursivos da utilização de termos do ramo cervejeiro na linguagem midiática. Mostra-se, primeiro, que sua utilização em textos de divulgação científica promove migração lexical da linguagem especializada para a linguagem geral. Em seguida, investiga-se se o item lexical porter é apenas um termo ou está se vocabularizando na língua inglesa, observando-se usos do termo na linguagem cotidiana e em sites especializados. Por fim, estuda-se a utilização de designações de cerveja na tradução do texto de divulgação científica e num texto jornalístico escrito em língua portuguesa com propósito publicitário. A circulação dos termos do ramo cervejeiro nos textos pesquisados indica que sua utilização na mídia faz parte de um movimento social mais amplo de divulgação e marketing dos produtos cervejeiros.

  13. All-optical tunable photonic crystal cavity

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan

    2010-01-01

    We demonstrate an ultra-small photonic crystal cavity with two resonant modes. An all-optical tuning operation based on the free-carrier plasma effect is, for the first time, realized utilizing a continuous wave light source. The termo-optical effect is minimized by isoproponal infiltration...

  14. LEVANTAMENTO, SELEÇÃO E SISTEMATIZAÇÃO DE TERMOS RELATIVOS AOS MEIOS DE HOSPEDAGEM

    Directory of Open Access Journals (Sweden)

    Júlia Moreira de Deus

    2016-12-01

    Full Text Available Está sendo realizado um projeto de pesquisa com a finalidade de elaborar um dicionário trilíngue (PortuguêsInglês-Espanhol com termos relacionados ao turismo. O dicionário visa contribuir com a comunicação no campo do turismo e disponibilizar uma fonte de consulta para profissionais e estudantes. A esta pesquisa coube levantar, selecionar e sistematizar os termos relativos aos meios de hospedagem. Para isso, foi feito um levantamento em cinco dicionários especializados e três obras que tratavam do assunto; foram selecionados os termos que designam meios de hospedagem;as definições e contextos foram inseridos em fichas e foram identificadas as principais características dos termos; foi organizado um mapa conceitual dos meios de hospedagem. Por fim, um especialista foi consultado para validar os termos. Os dados coletados nessa primeira etapa da pesquisa foram usados na redação das definições dos termos selecionados. Palavras-chave: Dicionário. Meios de Hospedagem. Terminologia.

  15. Termo de consentimento livre e esclarecido na prática reumatológica

    OpenAIRE

    Marques Filho,José

    2011-01-01

    O termo de consentimento livre e esclarecido (tcle) é um documento obrigatório nos protocolos de pesquisas com seres humanos. as normas que preconizam sua utilização são recentes na história da medicina, e o primeiro documento oficial que instituiu a necessidade do consentimento informado do sujeito de pesquisa foi o código de nuremberg (1947). Todas as normas posteriores referendaram a obrigatoriedade do consentimento informado em pesquisas. Entretanto, o consentimento informado, que represe...

  16. Comportamento de lactentes nascidos a termo pequenos para a idade gestacional no primeiro trimestre da vida

    OpenAIRE

    Mello,Bernadete Balanin A.; Gonçalves,Vanda M. Gimenes; Souza,Elisabete Abib P.

    2004-01-01

    O objetivo foi comparar o comportamento de lactentes nascidos a termo com peso adequado (AIG) a lactantes pequenos para a idade gestacional (PIG), no primeiro trimestre de vida. A amostra foi de 20 lactentes, avaliados no 1º, 2º e 3º meses. Foram utilizadas as Escalas Bayley de Desenvolvimento Infantil - II, com ênfase na Escala de Classificação do Comportamento (ECC). Houve diferença significativa entre os grupos no 2º mês, com maior número de lactentes PIG classificados como alterados na EC...

  17. Conhecendo alguns termos técnicos em inglês usados no curso de Edificações

    Directory of Open Access Journals (Sweden)

    Cláudia Regina Ponciano Fernandes

    2017-08-01

    Full Text Available Este artigo apresenta uma visão geral sobre os resultados de uma pesquisa voltada para termos técnicos em inglês, utilizados no curso Técnico em Edificações. O objetivo principal deste trabalho é proporcionar aos discentes de Língua Inglesa uma definição simples e breve de termos técnicos em Inglês que são frequentemente usados no curso. Os dados foram obtidos por meio de anotações pessoais e de material impresso dos discentes. Os procedimentos utilizados foram: identificação dos termos técnicos, sua organização em ordem alfabética e escrita de seus significados correspondentes em uma lista de termos que foi digitada e salva no Microsoft Word. Os pressupostos teóricos estão ancorados em conceitos de Lexicografia e Terminografia segundo Welker (2004 e Bevilacqua e Finatto (2006 como também em Lexicologia e Terminologia na perspectiva de Krieger (2006, 2011. Como resultado, produziu-se um glossário com 422 termos que podem ser acessados por um link do programa 4shared. O glossário também apresenta termos relacionados aos programas AutoCAD e Sketchup. Ele pode ser usado como uma ferramenta para ampliar o vocabulário técnico do discente e preencher pequenas lacunas em termos de material específico em Inglês, especialmente para os discentes que acabam de ingressar no curso Técnico em Edificações dos Institutos Federais. Esta pesquisa mostra uma maneira significativa de promover a aprendizagem do Inglês no ensino Técnico Integrado ao Ensino Médio, para além das aulas tradicionais

  18. Bebês pré-termo: aleitamento materno e evolução ponderal

    Directory of Open Access Journals (Sweden)

    Anelize Helena Sassá

    2014-07-01

    Full Text Available O objetivo do estudo foi identificar fatores associados à prática do aleitamento materno (AM, ao ganho ponderal e ao estado nutricional de bebês pré-termos durante os seis primeiros meses de vida e verificar correlação entre essas variáveis e características maternas e neonatais. Estudo analítico, tipo coorte, realizado com 42 bebês pré-termos nascidos entre maio e outubro de 2008. A prevalência de AM foi de 40,5% aos seis meses e a média de ganho ponderal variou entre 18 e 40g/dia. A prática de AM esteve associada ao menor peso e à menor idade gestacional de nascimento. O ganho ponderal apresentou correlação positiva com a idade gestacional e o peso ao nascer, a idade materna e a prática do AM aos 15 dias após a alta. Ser prematuro não impediu a prática do AM; entretanto, o ganho ponderal foi maior entre aqueles nascidos com melhores condições de crescimento e maturação intrauterina.

  19. Lapsos de língua e discurso: uma análise do termo nasciturno

    Directory of Open Access Journals (Sweden)

    Carolina P. Fedatto

    2017-03-01

    Full Text Available A partir de reflexões sobre erro, analogia e formação de palavras nos estudos da linguagem, da consideração do estatuto dos lapsos e atos falhos na psicanálise e das discussões da análise do discurso sobre o papel constitutivo da memória na estruturação da língua, o artigo apresenta uma análise do termo nasciturno, que apareceu como um lapso no contexto das polêmicas sobre o projeto de lei conhecido como Estatuto do Nascituro. Discutem-se as implicações entre a ordem da língua e a ordem do discurso na emergência de lapsos discursivos, isto é, formações lexicais que irrompem socialmente pela articulação da língua com o real da história. Pela consideração dos efeitos da poesia na língua e da exterioridade constitutiva, propõe-se uma análise do acontecimento do termo nasciturno, mostrando a imbricação entre forma linguística, incompletude do sentido e seu atravessamento pelo inconsciente e pela ideologia.

  20. Liquido cefalorraqueano no récem-nascido pré-termo sadio

    Directory of Open Access Journals (Sweden)

    F. A. C. V. Vaz

    1977-09-01

    Full Text Available Estudo da composição do LCR de 54 recém-nascidos prematuros sadios no segundo dia de vida. Os prematuros estudados precediam de gestações sem inter-corrências com parto não-traumático, apresentavam Apgar entre 6 e 9 aos 5 minutos de vida e não apresentavam anormalidades quanto ao exame clínico, neurológico, hematimétrico e gasométrico. Da composição do LCR foram estu-dades a citometria e as concentrações de proteínas totais, glicose, bilirrubina e hemoglobina. As estimativas encontradas permitem aceitar como limites das variações fisiológicas da composição do LCR do RN-PT os seguintes valores: leucócitos até 16 por mm ³; hemácias até 1.280 por mm3; proteínas totais até 300 mg/100 ml; bilirrubina de 10 a 80 µM/l; hemoglobina até 8 µM/l; glicose: cerca de 2/3 da concentração no sangue. Em relação à composição do LCR de 79 recém-nascidos normais a termo, avaliada mediante os mesmos métodos e no mesmo laboratório, são significativamente maiores as concentrações de proteínas totais e de bilirrubina, bem como estar presente a hemoglobina, pigmento não demonstrado no recém-nascido a termo. É discutida a importância da imaturidade da barreira hêmato-liquórica quanto às características do LCR apontadas, considerando-se encontrar-se ela ainda menos diferenciada no recém-nascido prematuro que no recém-nascido a termo.

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

    Directory of Open Access Journals (Sweden)

    Del Nero Ulisses

    2002-01-01

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

  2. Relevância das diferenças entre contratos futuros e a termo: o caso do trio

    OpenAIRE

    Andrade, Rafael de Godoy Oliveira

    2015-01-01

    Visando estudar as diferenças entre contratos futuros e contratos a termo no mercado cambial brasileiro, este trabalho foca no contrato de Dólar Futuro negociado na BM&FBOVESPA que, para vencimentos sem liquidez, é marcado a mercado pelo preço teórico dos contratos a termo. Uma simulação por Monte Carlo de uma carteira hedgeada contendo contratos de Dólar Futuro, DI Futuro e DDI Futuro mostra claramente que essa metodologia de marcação a mercado deveria ao menos ser revista For the purpose...

  3. Comportamento e informação na estrutura a termo das taxas de juros do Brasil

    OpenAIRE

    Novy, Luiz Gustavo Guimarães

    2010-01-01

    O comportamento da curva que relaciona o rendimento dos títulos de desconto negociados no sistema financeiro nacional e o seu prazo de vencimento, ou seja, da estrutura a termo das taxas de juros, é minusciosamenteestudado através da análise de componentes. principais. Através de duas equações de regressão busca-se discutir as ·informações implícitas nas taxas de juros a termo sobre as taxas de juros e prêmios esperados para o futuro.

  4. Cullen e a introdução do termo "neurose" na medicina

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    Mário Eduardo Costa Pereira

    2010-03-01

    Full Text Available O termo médico "neuroses" começa a ser empregado de forma técnica a partir de 1769, ano em que é publicada a primeira edição da célebre Synopsis Nosologiae Methodicae do médico escocês William Cullen (1710-1790. Tratava-se então, segundo um ordenamento classificatório inspirado na taxonomia de Lineu, da designação de uma classe de afecções gerais do sistema nervoso, não acompanhadas de febre e atingindo de forma privilegiada a sensibilidade e o movimento, reunindo quatro "ordens" específicas de fenômenos: os comas, as adinamias; as afecções espasmódicas sem febre e as vesânias, como a mania (loucura e a melancolia

  5. Determinantes Macroeconômicos da Estrutura a Termo da Taxa de Juros

    OpenAIRE

    Reis, Yuri Azevedo Pinto dos

    2014-01-01

    Este trabalho propõe a implementação de um modelo de três fatores em que os movimentos da Estrutura a Termo da Taxa de Juros são determinados por variáveis macroeconômicas observáveis. Desenvolvi o estudo com base na metodologia elaborada por Huse (2007), que propôs um novo modelo baseado nos estudos de Nelson e Siegel (1987) e Diebold e Li (2006). Os fatores utilizados foram: taxa de câmbio em reais por dólar, expectativa da taxa de inflação para daqui a doze meses, spread do Credit Default ...

  6. ARMAS NO TERMO DE MARIANA (1707-1736: LEGISLAÇÃO E DIREITO COMUM

    Directory of Open Access Journals (Sweden)

    Izabella Fátima Oliveira de Sales

    2010-12-01

    Full Text Available This paper aims to discuss the features of the legislation - related to the possession and use of weapons - established by the Portuguese Crown in their fields, as well as the influence of these procedures and customary practices of direct in Minas Gerais during the first three decades of the eighteenth century, especially in the Termo de Mariana. This approach allows us to infer issues about the nature of relations established between center and periphery, to the extent that the State created parameters that should be followed by society to maintain the established order, however, the legitimacy of such power was based on ample bargaining with social groups. In this context, one can see how the laws regarding weapons were adapted to the local context. Moreover, this study also contributes to thinking about the environment of violence and conflict that marked the mining region in its first occupations.

  7. Ruptura prematura das membranas amnióticas no pré-termo: fatores associados à displasia broncopulmonar

    OpenAIRE

    Gonçalves,Danieli Dias; Silva,Luiz Guilherme Pessoa da; Paula,Glaucio de Moraes; Bonfim,Olga; Moreira,Maria Elizabeth Lopes; Assumpção,Augusta Maria Batista; Figueira,Valéria Seild

    2010-01-01

    OBJETIVO: identificar os fatores obstétricos e neonatais associados ao desfecho de displasia broncopulmonar em pacientes com amniorrexe prematura no pré-termo. MÉTODOS: foram analisados 213 prontuários do Instituto Fernandes Figueira, entre 1998 e 2002, cujas pacientes evoluíram com quadro de amniorrexe prematura

  8. Variabilidade da frequência cardíaca em neonatos prematuros e de termo

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    Fabio Augusto Selig

    2011-06-01

    Full Text Available FUNDAMENTO: Várias publicações têm demonstrado a importância do sistema nervoso autônomo por meio dos componentes simpático e parassimpático na gerência da interação entre as diferentes partes do organismo humano. Esses estudos aplicaram técnicas lineares e não lineares (Teoria do Caos de avaliação em diferentes situações, doenças e faixas etárias, tendo como ferramenta a variabilidade da frequência cardíaca (VFC. OBJETIVO: Aplicar os conhecimentos das dinâmicas linear e não linear na avaliação de neonatos prematuros (NPT, analisando sua VFC e comparando com neonatos de termo (NT saudáveis. MÉTODOS: Quarenta e oito neonatos prematuros com diferentes idades gestacionais tiveram seus batimentos cardíacos captados com auxílio do equipamento Polar Advanced S810i e sua VFC obtida pelo registro dos intervalos RR. A VFC foi analisada nos domínios do tempo (SDNN, RMSSD, SD1/SD2, da frequência (VLF, LF, HF e a relação LF/HF e do caos (TAU e sua normalização [TAU(n], Expoente de Lyapunov e Entropia. Os NPT foram comparados com um grupo de 78 NT saudáveis e sem intercorrências perinatais com auxílio do teste não paramétrico de Kruskal-Wallis. RESULTADOS: Detectou-se diferença estatisticamente significante entre os grupos para todas as variáveis estudadas, tanto no domínio do tempo como nos da frequência e do caos. CONCLUSÃO: Neonatos prematuros exibem comportamento menos complexo da variabilidade da frequência cardíaca que neonatos de termo, fato comprovado nos domínios do tempo, da frequência e do caos. O estudo da variabilidade cardíaca nesse grupo pode ser considerado uma ferramenta a mais na avaliação da maturação autonômica e, consequentemente, da progressão para eutrofia.

  9. Transfusão de hemocomponentes em recém-nascidos de termo e prematuros

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    Albiero A.L.

    1998-01-01

    Full Text Available OBJETIVO: Comparar o consumo de hemocomponentes entre recém-nascidos (RN de termo (RNT e pré-termo (RNPT e correlacionar esse consumo ao tipo de tratamento dispensado à sua patologia: clínico ou cirúrgico; acidentes hemorrágicos e sobrevida. CASUÍSTICA E METODOLOGIA: 48 RNs classificados em dois grupos: 26 RNT e 22 RNPT receberam 251 unidades de hemocomponentes: 177 unidades de concentrado de hemácias (CH, 36 de concentrado de plaquetas (CP, 30 de plasma fresco congelado (PFC e oito de sangue total (ST, no período de 186 dias. Foi analisado o consumo de hemocomponentes em cada grupo, e na razão do número de RNs vivos por dia, até o 120º dia. RESULTADOS: O consumo médio de hemocomponentes foi de 7,31 unidades para RNPT e 3,46 para RNT. A análise de consumo diário revelou que a maior parte ocorreu em RNs sob tratamento clínico antes do 60º dia de vida (d.v. e que um aumento após o 86º d.v. pode ser atribuído a um aumento de cirurgias nessa fase. Os acidentes hemorrágicos predominaram em RNPT com plaquetometria inferior a 60.000/mm³. Foi constatada uma tendência inversamente proporcional entre o número de transfusões e a sobrevida. CONCLUSÕES: Os RNPT consumiram mais hemocomponentes que os RNT. Esse consumo estava ligado à patologia de base. Foi sugerido que a transfusão profilática de CP em RNPT poderia reduzir o número de hemorragias, além do consumo de CH nesse grupo. Mais de dez transfusões de hemocomponentes nos primeiros 120 d.v., em ambos os grupos, parece constituir marcador de mau prognóstico.

  10. UTILIZAÇÃO DE ABRIGOS TERMO-HIGROMÉTRICOS ALTERNATIVOS

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    Marcos de Oliveira Valin Júnior

    2016-03-01

    Full Text Available Este trabalho teve por objetivo levantar os tipos de abrigos alternativos para termo-higrômetros (temperatura e umidade utilizados, reproduzi-los e testa-los para comparação dos dados obtidos a partir de um padrão de referência, instalados em campo aberto para garantir o mesmo ambiente para o estudo, visando avaliar e qualificar esses abrigos quanto ao seu desempenho, custo e praticidade de manuseio para utilização em pesquisas de clima urbano. Com os dados coletados realizaram-se diversas analises gráficas e estáticas. Com base no desempenho dos abrigos alternativos analisados, tem-se que os abrigos fabricados com tubo de PVC na vertical e com pote de sorvete não se demonstram eficientes para a coleta de dados em pontos fixos, principalmente se utilizados durante o dia. Quanto aos demais tipos, o com pratos plásticos, tubo de PVC na horizontal e casa de madeira, se mostraram alternativas viáveis quanto ao desempenho, cabendo analisar o local onde será utilizado para definir qual deles melhor se adapta, pois o horizontal depende de já conhecer o sentido da direção do vento, o de madeira do espaço disponível devido ao seu tamanho e peso e o de pratos depende da disponibilidade de pratos plásticos na cor branca.

  11. Características da sucção não-nutritiva em RN a termo e pré-termo tardio Characteristics of non-nutritive sucking in full-term and late preterm infants

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    Ana Paula d'Oliveira Gheti Kao

    2011-09-01

    Full Text Available OBJETIVO: Comparar os parâmetros de sucção não nutritiva de recém-nascidos a termo e pré-termo tardio. MÉTODOS: Os recém-nascidos foram divididos em dois grupos, pré-termo tardio (RNPT tardio e a termo (RN a termo e, submetidos à avaliação da sucção não-nutritiva utilizando-se um protocolo adaptado da Escala de Avaliação Motora Oral. Foi realizada análise estatística para comparação dos grupos. RESULTADOS: Os reflexos de procura e de sucção foram menos frequentes nos RNPT tardio, comparados aos RN a termo, assim como a preensão palmar e mãos em linha média. A maioria dos RNPT tardio apresentou sono leve ou estava sonolento antes da avaliação. Os RNPT tardio apresentaram predominantemente sucção esporádica ou grupos de sucção com pausas longas e travamento e/ou tremores de mandíbula. A retração de língua e a protrusão de língua foram mais presentes nos RNPT tardio e o canolamento de língua nos RN a termo. CONCLUSÃO: Prontidão para a mamada, estado comportamental, postura corporal, padrão e força de sucção e movimentos de língua foram os parâmetros menos frequentes nos RNPT tardio em relação aos RN a termo.PURPOSE: To compare non-nutritive sucking parameters between late preterm and full-term infants. METHODS: Infants were divided into two groups, full-term and late preterm, and were submitted to non-nutritive sucking assessment using a protocol adapted from the Oral Motor Assessment Scale. Statistical analysis was conducted for comparison between the groups. RESULTS: The seeking and sucking reflexes were less frequent in late preterm than in full-term newborns, as well as palmar grip and hands in the midline. Most late preterm infants presented light sleep or drowsiness before the assessment. Late preterm subjects predominantly presented sporadic sucking or blocks of sucking with long pauses and mandibular locking and/or tremors. Tongue retraction and protrusion were mostly present in late preterm

  12. O cuidado de enfermagem ao neonato pré-termo em unidade neonatal: perspectiva de profissionais de enfermagem

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    Loiana Gomes Silva

    2012-09-01

    Full Text Available A prematuridade põe em risco a vida de neonatos pela imaturidade morfológica e funcional de seus órgãos. Objetivou-se com este estudo analisar a práxis cuidativa da equipe de enfermagem de uma Unidade Neonatal ao neonato pré-termo. Trata-se de estudo de natureza qualitativa, desenvolvido na Unidade Neonatal de um hospital público em Jequié-BA com onze profissionais da equipe de enfermagem. Utilizou-se entrevista semiestruturada para coleta de dados, estes foram analisados por meio da técnica de análise de conteúdo temática. Os resultados revelaram que os profissionais de enfermagem focam suas práticas cuidativas ao neonato pré-termo com predominância nos aspectos biológicos, embora valorizem os aspectos subjetivos que envolvem o cuidado de enfermagem. Dessa maneira, faz-se necessário a implantação das normas de humanização de cuidado aos neonatos pré-termo de modo que os profissionais de enfermagem possam incorporar na íntegra os seus pressupostos.

  13. Análise das Opiniões Emitidas nas Cartas-Comentários sobre o Termo Prudence

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    Victor Ranieri Bomfim Sampaio de Araújo

    2015-01-01

    Full Text Available Desde 2001, o International Accounting Standards Board (Iasb tem feito esforços para a revisão da Conceptual Framework ou Estrutura Conceitual (EC. Para tanto, emitiu os Discussion Papers (DP, objetivando coletar opiniões dos interessados em Contabilidade sobre diversos aspectos da EC. Entre os pontos discutidos, tem-se a inclusão, ou não, da Prudência na EC. Portanto, este estudo objetiva analisar as opiniões emitidas nas cartas-comentários em resposta aos DPs de 2006 e 2013 acerca da exclusão do termo Prudência da EC. A pesquisa foi realizada pela análise de conteúdo de 420 cartas-comentários (C omment Letters encaminhadas ao Iasb, sendo identificadas 176 que contêm os termos Prudence/Conservatism , em que 117 dessas são a favor da inclusão do termo. Entre aqueles contrários à inserção, a justificativa prevalecente é a existência do conflito entre Prudência e neutralidade. As opiniões dos respondentes também foram segregadas por localidade e grupos de interesses, constatando que os respondentes europeus são mais favoráveis à inclusão do termo, enquanto que a América Anglo-Saxônica é o que menos defende. No que diz respeito aos grupos de interesses, o que mais se mostrou a favor da inserção do termo foram os Preparadores, enquanto que as Instituições Financeiras foram os agentes mais desfavoráveis. Utilizando a Análise Kappa , observou-se que o grau de concordância de opinião entre os respondentes indica uma concordância fraca ao total das amostras, sugerindo que é preciso maior debate e reflexão sobre o tema.

  14. The influence of climate change on wine production - the case of the Touriga Nacional grape variety (Quinta dos Termos, Portugal)

    Science.gov (United States)

    Fonseca, João

    2017-04-01

    The regional and local climate, heavily influenced by global climate change, has strong implications for agriculture. Wine production which has specific characteristics in terms of climate and soil is undoubtedly one of the economic activities strongly influenced by climate change. Quinta dos Termos located in Beira Interior (Belmonte, Portugal) is the largest wine producer in the DOC Beira Interior region, producing premium to hiper premium wines of excellence, marketed at both national and international levels, and cultivates the vineyards according to the rules of Integrated Crop Management. Moreover, grapes are free from herbicides, pesticides or any other chemicals that can be harmful to the environment and health. These factors have contributed to the socio-economic development of the region, creating wealth, favoring employment and promoting tourism. The quality of the wines produced by Quinta dos Termos result from its terroir, given its granite region, the sun exposure, the wind protection, the atmospheric humidity and temperature, the soil water content, the mineralogical/organic composition and soil porosity. These factors favor unique conditions for the cultivation of Touriga Nacional grape variety, which is recognized by its extremely complex color and aroma, which allows the production of wines with great balance and a good ageing potential. Touriga Nacional, a red grape variety of Portuguese origin with high qualitative excellence and reputation and much appreciated worldwide, is versatile to several types of soils and resistant to high thermal amplitudes. Nevertheless, the climatic changes that has been gradually verified, the type of crop management, and in particular the reputation of Touriga Nacional grape variety, may be compromised in the long term, given that these characteristics are strongly influenced by the climate and soil. Aware of that, Quinta dos Termos has been performing a monitoring of the vineyards in terms of pedological treatment

  15. Algumas considerações sobre o termo afânise a partir de E. Jones e J. Lacan

    Directory of Open Access Journals (Sweden)

    Daniela Scheinkman Chatelard

    2001-12-01

    Full Text Available Em sua primeira parte, este artigo propõe-se a retomar e a desenvolver o termo afânise, tal como foi forjado por Ernest Jones. Na segunda parte, trata-se de acrescentar a importância dada por Jacques Lacan a este termo: do registro do puro desaparecimento do desejo, em sua relação com a castração, como foi sustentado por E. Jones, passamos ao registro do desaparecimento do sujeito, enquanto sujeito dividido e desejante. Para isso, recorremos ao exemplo do personagem literário, Hamlet, da tragédia de Shakespeare.Some considerations about the aphanisis term from E. Jones and J. Lacan. The aim of the article in its first part is to retake and to develop the term aphanisis, such as forged by Ernest Jones. In its second part, the purpose is to add to this term the importance given by Jacques Lacan : from the register of the pure disappearing of desire in its relation to castration, as supported by Jones, we will pass on to the register of the disappearing of the subject, while in the form of a divided and desiring subject. Therefore, we will use the example of the literary character, Hamlet, taken from Shakespeare's tragedy.

  16. COMPOSIÇÃO ELETROLÍTICA E MINERAL DO LEITE DE LACTANTES A TERMO PRÉ E PÓS-PASTEURIZAÇÃO E DE LEITE CRU DE MÃES DE RECÉM-NASCIDOS PRÉ-TERMO

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    Carla Regina Bianchi Codo

    2018-02-01

    Full Text Available RESUMO Objetivo: Determinar e comparar as concentrações de eletrólitos e minerais no leite humano em três grupos: amostras analisadas antes e após pasteurização de lactantes doadoras a termo e amostra de leite cru colhida à beira do leito de mães de recém-nascidos pré-termo. Métodos: Estudo descritivo de corte transversal. Foram dosadas concentrações de cálcio (Ca, fósforo (P, magnésio (Mg, sódio (Na e potássio (K em amostras aleatórias de leite humano nos três grupos. As amostras foram analisadas por mineralização ácida assistida por radiação micro-ondas e posteriormente por espectrometria de emissão óptica com plasma indutivamente acoplado e expressas em mg/L, com cálculo de médias e desvio padrão. A comparação entre os grupos foi feita por análise de variância (ANOVA/teste de Tukey. Nível de significância aceito de 5%. Resultados: Observou-se redução significante dos teores de Ca (259,4±96,8 vs. 217,0±54,9; p=0,003, P (139,1±51,7 vs. 116,8±33,3; p=0,004 e K (580,8±177,1 vs. 470,9±109,4; p<0,0001 após a pasteurização. As amostras de leite cru colhidas à beira do leito apresentaram teores estatisticamente mais elevados de Na (2 vezes do que o leite a termo de doadora. Ca e P só atingiriam a ingestão recomendada pela European Society of Pediatric Gastroenterology, Hepatology and Nutrition se o leite materno fosse ofertado em volume de 60 mL a cada 3 horas. Concentrações de Mg não diferiram entre os grupos. Conclusões: Houve uma redução significativa de Ca, P e K nas amostras após pasteurização e os valores de Na no leite cru coletado à beira do leito foram superiores àqueles pré-pasteurização.

  17. EVOLUCIÓN DEL COMPORTAMIENTO VISCOELÁSTICO DEL ASFALTO INDUCIDA BAJO TERMO-OXIDACIÓN IN SITU EN UN REO-REACTOR

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    XIOMARA VARGAS

    2008-01-01

    Full Text Available En este artículo se presentan los resultados del proceso de termo-oxidación de asfalto realizados por primera vez en un reo-reactor. El comportamiento viscoelástico del asfalto pudo ser representado por una ley de potencia (G'(w - wn, G'' (w - w1. La variación del exponente 'n' reflejó los cambios estructurales del asfalto inducidos por el proceso de termo-oxidación. En el intervalo de frecuencia experimental y a 200 y 250°C, los módulos elástico G' y viscoso G'' mostraron una relación del tipo: G'' (w - wn y G' (w ~ wn, este comportamiento es equivalente a un 'gel-débil' y confirma los cambios estructurales del asfalto inducidos por el envejecimiento termo-oxidativo.

  18. Equivalência lexical e aspectos morfológicos de termos em português e espanhol do domínio da dermatologia

    OpenAIRE

    Delvizio, Ivanir Azevedo [UNESP

    2006-01-01

    O objetivo principal dessa pesquisa foi realizar a busca das equivalências em espanhol para um conjunto de termos, em português, da área da Dermatologia, e analisar as relações de equivalência mantidas entre esses termos em uma abordagem contrastiva. Para tanto, tomamos como base os trabalhos de Alpízar-Castillo (1997), Dubuc (1985) e Felber (1987) sobre Terminologia Bilíngüe. Nosso primeiro passo foi realizar um breve estudo sobre a área da Dermatologia para adquirirmos uma visão geral da ex...

  19. Notas sobre o termo inicial dos juros de mora e o artigo 407 do Código Civil

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    Gustavo Tepedino

    2017-03-01

    Full Text Available A definição do termo inicial dos juros de mora exige a adequada compreensão de sua função, tal seja, a de indenizar a vítima que fora indevidamente privada do capital que lhe era devido como decorrência da violação de dever obrigacional ou legal. Assumindo como premissa esta função, deve ser superada a dificuldade em se admitir a fluência de juros relacionados à obrigação que, resultando do inadimplemento, não possui objeto previamente determinado. Contabilizar os juros somente após a fixação do valor principal devido, por meio da leitura isolada do art. 407 do Código Civil, afigura-se incompatível com a função dos juros moratórios no ordenamento jurídico brasileiro, bem como revela contrariedade à ratio do dispositivo mencionado, analisado no artigo sob perspectiva histórico-sistemática.

  20. Abuso científico do termo 'caboclo'? Dúvidas de representação e autoridade

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    Richard Pace

    Full Text Available Os 'caboclos' da Amazônia brasileira estão classificados variavelmente como camponeses, extratores, povo rústico e descendentes miscigenados de europeus, indígenas e africanos. Em quase todos os usos se reconhece um tom pejorativo e raramente usado para chamar uma pessoa do mesmo nível social. As poucas pessoas que se identificam como 'caboclo' usam a palavra para referir-se a si mesmos, a não ser em condições especiais. Aceita-se que uma das finalidades das ciências sociais, particularmente a antropologia, é entender todas as culturas no mesmo nível e dar-lhes a mesma integridade que damos a nossa. Por que, então, insistimos em usar este termo? Esta pesquisa examina esta dúvida através da discussão sobre a representação e o uso de autoridade na documentação etnográfica

  1. O termo estratégia: um conceito útil para a lingüística aplicada?

    Directory of Open Access Journals (Sweden)

    John Robert Schmitz

    2001-02-01

    Full Text Available

    O termo estratégia é usado em certos casos na literatura especializada de lingüística aplicada sem muita precisão, pois, para alguns pesquisadores, ele é uma técnica; para outros, é método, de ensino e, para outros ainda, refere-se aos hábitos de estudo ou estilo cognitivo dos aprendizes. Outro problema é a pletora de estratégias propostas sem rigor na demarcação de diferenças: estratégias de comunicação (communication strategies, estratégias de aprendizagem (learning strategies, estratégias de aquisição (acquisition strategies e estratégias de ensino (teaching strategies. Apesar desses problemas, as pesquisas na área de estratégias são promissoras, já que o treinamento explícito em sua utilização ensina os aprendizes a: (i saber usar novas estratégias, (ii avaliar a eficiência de diferentes tipos; e (iii decidir quando é procedente transferir uma determinada estratégia para uma nova situação.

  2. Research and the (free and informed consent A pesquisa e o termo de consentimento livre e esclarecido

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    Maria Helena Villas Bôas Concone

    2008-04-01

    Full Text Available The aim of this article was to reflect about the Free and Informed Consent (IC in qualitative researches in the health field. Coming from the experience of being part of a CER (Committee for Ethic in Research in the health area the authoresses place in debate some important questions, exploring them and conducting suggestions. One of these questions and topic of analysis is the meaning of IC, as for the participant as for the researcher.Este artigo teve como objetivo refletir sobre o Termo de Consentimento Livre e Esclarecido (TCLE em pesquisas qualitativas no campo da saúde. Partindo da sua experiência de pertencimento a um CEP (Comitê de Ética em Pesquisa, na área da saúde, as autoras colocam em discussão algumas questões importantes, problematizando-as e encaminhando sugestões. Uma dessas questões e objeto da reflexão é o significado do TCLE, tanto para o participante como para o pesquisador.

  3. Estudo do desenvolvimento da função motora aos 8 e 12 meses de idade em crianças pré-termo e a termo Study of motor function at 8 and 12 months of age in preterm and at term children

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    Marisa C. Mancini

    2002-12-01

    Full Text Available OBJETIVO: Comparar o desenvolvimento da função motora de crianças nascidas pré-termo com crianças nascidas a termo, aos 8 e 12 meses de idade. Investigar a relação entre a qualidade motora aos 8 meses e a habilidade motora aos 12 meses. MÉTODO: Trinta e duas crianças participaram deste estudo: 16 nascidas pré-termo (grupo de risco e 16 nascidas a termo (grupo controle. A movimentação espontânea das crianças foi avaliada aos 8 meses e as habilidades e independência em mobilidade foram avaliadas aos 12 meses de idade (idades corrigidas para grupo pré-termo, utilizando-se testes infantis padronizados (AIMS e PEDI, respectivamente. Os dados foram analisados através dos textes t de Student para grupos independentes (comparação entre grupos e de correlação de Pearson (comparação intra grupo. RESULTADOS: Não foi evidenciada diferença significativa na comparação de crianças nascidas a termo com as pré-termo nem aos 8 nem aos 12 meses de idade. No grupo controle, foi observada relação significativa (r=0,67; p=0,004 entre movimentação aos 8 meses e habilidade de mobilidade aos 12 meses. No grupo de risco, houve relação significativa entre habilidade e independência em mobilidade aos 12 meses de idade corrigida (r=0,80; p=0,0001. CONCLUSÃO: Na ausência de outros distúrbios e com correção da idade em pré-termos, o desenvolvimento motor pode ser semelhante ao de crianças nascidas a termo. A forma pela qual as crianças nascidas pré-termo adquirem suas habilidades funcionais parece ocorrer de modo diferente da observada em crianças a termo.OBJECTIVE: To compare the development of motor function in children born preterm with those born at term, at 8 and 12 months of age. To investigate the relation of motor function quality at the age of 8 months with motor ability at 12 months. METHOD: Thirty-two children participated in this study: 16 were born preterm (risk group and 16 were born at term (control group. The

  4. Dopplervelocimetria de artéria mesentérica superior em recém-nascidos a termo

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    Badaró-Marques Carmen Solange

    2002-01-01

    Full Text Available OBJETIVO: A avaliação do fluxo sangüíneo mesentérico utilizando-se a Dopplervelocimetria transcutânea de artéria mesentérica superior (AMS é método não invasivo que permite avaliar fatores envolvidos na perfusão sangüínea intestinal. Este estudo teve como objetivo determinar as variáveis Dopplervelocimétricas da AMS em recém-nascidos normais a termo, relacionando-as aos fatores ligados a gestação e crescimento fetal. MÉTODOS: A amostra continha 58 mães e 59 recém-nascidos a termo (1 gestação gemelar, cujos partos ocorreram no Hospital Israelita Albert Einstein. Utilizou-se equipamento Toshiba SSH 140 com sistema duplex-Doppler colorido de alta resolução, avaliando-se a AMS na sua origem, determinando-se calibre, velocidade sistólica, velocidade diastólica, velocidade média e índices de resistência e pulsatilidade. RESULTADOS: Verificou-se que a média do calibre da artéria mesentérica superior foi 1.94 mm, a média da velocidade sistólica. 86.47 cm/s, a média da velocidade diastólica 17.66 cm/s e a média da velocidade média, 36.93 cm/s. Os valores médios dos índices de resistência e pulsatilidade foram respectivamente 0.79 e 1.91. O calibre da AMS correlacionou-se positivamente com o peso de nascimento e negativamente com o perímetro cefálico ; velocidades e índices guardam relação com os dados antropométricos do recém-nascido, com o número de horas de vida, com o número de minutos em jejum e com o peso da mãe no fim da gestação. CONCLUSÃO: As variáveis Doppleervelocimetricas estão relacionadas a variáveis maternas e dos recém-nascidos, discutem-se fatores possivelmente implicados na associação. Sexo do recém-nascido e peso da mãe no inicio da gestação não alteraram nossos resultados.

  5. DO INCENTIVO À CRIMINALIZAÇÃO: OS TERMOS DE AJUSTE DE CONDUTA NA ORIZICULTURA EM SANTA CATARINA - BRASIL

    Directory of Open Access Journals (Sweden)

    Alfredo Celso Fantini

    2014-03-01

    Full Text Available Em Santa Catarina os Termos de Ajuste de Conduta (TACs vêm ganhando espaço como estratégia para garantir, na zona rural, a recuperação de áreas de preservação permanente, principalmente as matas ciliares. No caso dos plantadores de arroz a situação é, no mínimo, discutível: agricultores antes incentivados pelo Estado a usarem para a produção toda a área de várzea, até o limite dos rios, são obrigados agora a recuperarem a vegetação ciliar “que nunca deveria ter sido suprimida”. Ignorando a complexidade da questão, o Ministério Público adotou o comando e controle para resolver “o problema”. Passados três anos, quase nada aconteceu na prática. Neste artigo, usamos uma abordagem sistêmica para compreender a situação-problema e apontar encaminhamentos para a sua melhoria. Em um estudo de caso realizado em Jacinto Machado-SC, foram utilizados métodos qualitativos e quantitativos (análise documental, entrevistas, inventários e oficinas e principalmente a Soft System Methodology (SSM. Os resultados revelaram que a mata ciliar é só mais um elemento de um complexo sistema de interesses, onde fatores sociais, culturais, ambientais e econômicos interagem dinamicamente. Apontam, também, a necessidade de uma aproximação entre os interessados na situação-problema para tornar possível uma acomodação entre as diferentes visões de mundo dos envolvidos

  6. Estudo da Estabilização Termo-Oxidativa de Fitas e Feixes de Fibras de Poliacrilonitrila

    Directory of Open Access Journals (Sweden)

    Costa Andréa M. A. R.

    2002-01-01

    Full Text Available Os estudos relacionados ao processo de fabricação de fibras de carbono indicam que a etapa de estabilização termo-oxidativa das fibras precursoras é limitante, envolvendo reações químicas complexas e mudanças na estrutura física das fibras. Com o objetivo de se conhecer melhor a etapa de estabilização e eliminar gastos em testes experimentais, a modelagem e a simulação surgem para tentar otimizar este processo. Apresenta-se neste trabalho um modelo matemático para a etapa de estabilização de uma fita de fibras de poliacrilonitrila. As equações do modelo descrevem as principais reações químicas de estabilização, a difusão de oxigênio e a transferência de calor na fita. Para a resolução do modelo foi desenvolvido um programa computacional na linguagem Fortran, utilizando os métodos de Colocação Ortogonal e Rungefraction three-quarters Kutta Semi-implícito. Foram obtidos resultados de temperaturas e concentrações na fita de fibras de poliacrilonitrila em função do tempo de estabilização e da posição na espessura da fita. Estes resultados foram analisados e comparados com os simulados em um feixe de fibras de poliacrilonitrila e indicaram que a transferência de calor na fita é melhor do que no feixe e conseqüentemente as reações exotérmicas são mais controladas.

  7. Efeitos da corticoterapia materna nos valores hemogasométricos de cordeiros nascidos a termo e prematuros

    Directory of Open Access Journals (Sweden)

    Francisco Leydson Formiga Feitosa

    Full Text Available RESUMO: O objetivo do estudo foi avaliar as variáveis hemogasométricas de cordeiros nascidos a termo e prematuros do nascimento às 48 horas de vida. Foram constituídos quatros grupos experimentais: PN (cordeiros nascidos de parto normal, n=15, média de 146 dias de gestação; PNDEX (cordeiros nascidos de parto normal, cujas mães receberam 16 mg de dexametasona aos 141 de gestação, n=8, média de 143 dias de gestação; PRE (cordeiros prematuros nascidos de cesarianas aos 138 dias de gestação, n=10 e PREDEX (cordeiros prematuros nascidos de cesarianas aos 138 dias de gestação, cujas mães receberam 16 mg de dexametasona dois dias antes do parto, n=9. Imediatamente após o nascimento, os cordeiros de todos os grupos apresentaram quadro de acidose respiratória (pH baixo e pCO2 elevada, com maior ênfase nos animais prematuros. A concentração de HCO3 - diminuiu entre 15 e 60 minutos de vida, principalmente nos grupos PRE e PREDEX, com posterior aumento no M24h. Os valores de diferença de base foram menores nos cordeiros prematuros, os quais apresentaram respiração abdominal, intensa dispneia e grande quantidade de líquido pulmonar. A estabilização do equilíbrio ácidobase ocorreu em todos os animais ao longo das primeiras 24 horas de vida. A dexametasona teve influência positiva sobre a condição clínica dos animais prematuros, resultando em adequada ventilação e perfusão tecidual, o que garantiu maior taxa de sobrevivência.

  8. Crystals in crystals

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Schmidt, I.; Carlsson, A.

    2005-01-01

    A major factor governing the performance of catalytically active particles supported on a zeolite carrier is the degree of dispersion. It is shown that the introduction of noncrystallographic mesopores into zeolite single crystals (silicalite-1, ZSM-5) may increase the degree of particle dispersion....... As representative examples, a metal (Pt), an alloy (PtSn), and a metal carbide (beta-Mo2C) were supported on conventional and mesoporous zeolite carriers, respectively, and the degree of particle dispersion was compared by TEM imaging. On conventional zeolites, the supported material aggregated on the outer surface...

  9. Virtual Crystallizer

    Energy Technology Data Exchange (ETDEWEB)

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  10. single crystals

    Indian Academy of Sciences (India)

    2018-05-18

    May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.

  11. Crystal Systems.

    Science.gov (United States)

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  12. Monomial Crystals and Partition Crystals

    Science.gov (United States)

    Tingley, Peter

    2010-04-01

    Recently Fayers introduced a large family of combinatorial realizations of the fundamental crystal B(Λ0) for ^sln, where the vertices are indexed by certain partitions. He showed that special cases of this construction agree with the Misra-Miwa realization and with Berg's ladder crystal. Here we show that another special case is naturally isomorphic to a realization using Nakajima's monomial crystal.

  13. Análise da utilização na prática dos termos atribuídos aos fenômenos de enfermagem da CIPE-Versão Alfa

    Directory of Open Access Journals (Sweden)

    Maria Miriam Lima da Nóbrega

    2001-09-01

    Full Text Available Este estudo teve como propósito a análise da utilização dos termos atribuídos aos fenômenos de enfermagem na prática das enfermeiras paraibanas. Os resultados evidenciam que todos os termos são utilizados pelas enfermeiras, com alguma freqüência. No que diz respeito à utilização dos termos, de acordo com o estrato amostral, os resultados evidenciam que as enfermeiras dos demais Municípios Paraibanos utilizam um maior número de termos, estatisticamente significativo, quando comparado com os dois outros estratos - João Pessoa e Campina Grande. A partir dos resultados do estudo, pode-se concluir, que os termos atribuídos aos fenômenos constantes na CIPE - Versão Alfa representam problemas ou situações da prática de enfermagem das enfermeiras paraibanas, corroborando a afirmação do Conselho Internacional de Enfermeiras de que estes termos são comuns às enfermeiras de todo o mundo.

  14. Avaliação neurológica pelo método Dubowitz em recém-nascidos prematuros com idade corrigida de termo comparada a de nascidos a termo Neonatal neurological assessment by the Dubowitz method in preterm infants at term corrected age compared with term infants

    Directory of Open Access Journals (Sweden)

    Marina Ortega Golin

    2009-12-01

    Full Text Available OBJETIVO: Comparar a avaliação neurológica de recém-nascidos pré-termo em idade de termo com a de recém-nascidos a termo e verificar a presença de associação entre alterações na avaliação neurológica e características e intercorrências clínicas nos prematuros. MÉTODO: Estudo transversal de 60 nascidos a termo e 30 prematuros do Hospital Estadual Mário Covas, em Santo André (SP, avaliados pelo método Dubowitz. Os pontos de corte da pontuação total foram 30,5 e 26 para comparar recém-nascidos pré-termo e a termo, respectivamente. Os prematuros foram avaliados com idade correspondente ao termo, na 37ª semana, e os do grupo controle, 48 horas após o nascimento. Todos os neonatos foram avaliados pela mesma examinadora, entre as mamadas, nos estágios 4 e 5 de sono e vigília. Para análise estatística, utilizaram-se testes de associação. RESULTADOS: 90% dos nascidos pré-termo não atingiram a pontuação esperada para a idade de termo (pOBJECTIVE: To compare neonatal neurological assessment of preterm newborn infants at term corrected age with term infants, and to identify the presence of association between neurologic abnormalities in preterm infants and demographic characteristics and neonatal clinical conditions. METHODS: This cross-sectional study enrolled 60 term and 30 preterm infants born at the Mario Covas State Hospital in Santo André, São Paulo, Brazil. The Dubowitz method was applied to assess neurobehavior. The total score cut-offs of 30.5 and 26 were used to compare respectively preterm and term infants and to analyze the variables related to performance in the preterm group. Preterm newborns were evaluated at 37 post-conceptual weeks and the control group was evaluated 48 hours after birth. All newborns were evaluated by the same neurologist, between feedings and at sleep-awake stages 4 or 5. Statistical analysis was performed by association tests. RESULTS: 90% of the preterm infants did not reach the

  15. RNA Crystallization

    Science.gov (United States)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  16. Crystallization mechanisms of acicular crystals

    Science.gov (United States)

    Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

    2008-01-01

    In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.

  17. A hípotese das expectativas na estrutura a termo de juros no Brasil: uma aplicação de modelos de valor presente

    OpenAIRE

    Lima, Alexandre Maia Correia

    2002-01-01

    Utilizando dados financeiros brasileiros da BM&F, testa-se a validade do modelo de valor pre- sente (MVP) na estrutura a termo de juros, também conhecido na literatura como Hipótese das Expectativas. Estes modelos relacionam a taxa de juros de longo prazo à uma média das taxas de juros de curto-prazo mais um prêmio de risco, invariante no tempo. Associada a estes modelos está a questão da previsibilidade dos retornos de ativos financeiros ou, mais especificamente, a previsibilidade n...

  18. Associação da presença de DNA genômico de diferentes bactérias em sangue de recém-nascidos pré-termo e termo com ruptura prematura de membrana

    OpenAIRE

    Appel, Kelly Lopes de Araújo

    2015-01-01

    A associação de ruptura prematura de membranas (RPM) e infecção neonatal precoce tem sido alvo de vários estudos, pois os microrganismos responsáveis pela infecção neonatal relacionada com RPM são aqueles encontrados na microbiota vaginal normal e patogênica das gestantes. Assim, para avaliar a associação da RPM com a presença do DNA genômico de diferentes bactérias em recém-nascidos (RNs) pré-termo e a termo foi realizado um estudo observacional, transversal, com RNs provenientes de mães com...

  19. A hipótese das expectativas na estrutura a termo de juros no Brasil: uma aplicação de modelos de valor presente

    Directory of Open Access Journals (Sweden)

    Alexandre Maia Correia Lima

    2003-12-01

    Full Text Available Utilizando dados financeiros brasileiros da BM&F, testa-se a validade do modelo de valor presente na estrutura a termo de juros, também conhecido na literatura como Hipótese das Expectativas. Estes modelos relacionam a taxa de juros de longo prazo à uma média das taxas de juros de curto-prazo mais um prêmio de risco, invariante no tempo. Associada a estes modelos está a questão da previsibilidade dos retornos de ativos financeiros ou, mais especificamente, à previsibilidade na evolução das taxas de juros. Neste artigo é realizada uma análise multivariada num arcabouço de séries temporais utilizando a técnica de Auto-Regressão Vetorial. Os resultados empíricos aceitam apenas parcialmente a Hipótese das Expectativas para a estrutura a termo de juros brasileira.Using Brazilian financial data provided by BMF we test the expectations hypothesis of interest rates present value models (Campbell and Shiller, 1987. The empirical results are ambiguos: we find a common factor for ''long'' and short interest rates (cointegration, but present-value restrictions are rejected at 10% significance but not at 5%.

  20. Abordagem holística do termo pessoa em um estudo empírico: uma análise crítica

    Directory of Open Access Journals (Sweden)

    David Lopes Neto

    Full Text Available O estudo analisa a semântica e a estrutura do termo pessoa (mulheres com HIV, mediante abordagem holística fundamentada no Modelo de Adaptação de Roy (Veritivity e na fenomenologia de Heidegger (Dasein. Pesquisa extraída da literatura das Ciências Enfermagem e Filosofia, através da técnica de documentação indireta, com utilização do modelo de análise de teoria de Chinn & Kramer, através do qual foram analisados os seguintes aspectos: objetividade, simplicidade, generalidade, acessibilidade e importância dos conceitos de pessoa e holismo no estudo empírico "Nutritional adaptation of women living with HIV: a pilot study", publicado na revista Holistic Nursing Practice, em 1997. Criticamente, a interpretação do termo pessoa se deu pela compreensão do ser enquanto um ser ôntico-ontológico, como forma de percepção verdadeira do sentido do ser (pessoa, como uma estrutura universal vivente em um mundo antropológico e social, ao qual mulheres com HIV podem se adaptar ao novo estilo de vida e receber atenção integral da enfermagem, principalmente no que concerne ao aspecto nutricional.

  1. Abordagem holística do termo pessoa em um estudo empírico: uma análise crítica

    Directory of Open Access Journals (Sweden)

    Lopes Neto David

    2002-01-01

    Full Text Available O estudo analisa a semântica e a estrutura do termo pessoa (mulheres com HIV, mediante abordagem holística fundamentada no Modelo de Adaptação de Roy (Veritivity e na fenomenologia de Heidegger (Dasein. Pesquisa extraída da literatura das Ciências Enfermagem e Filosofia, através da técnica de documentação indireta, com utilização do modelo de análise de teoria de Chinn & Kramer, através do qual foram analisados os seguintes aspectos: objetividade, simplicidade, generalidade, acessibilidade e importância dos conceitos de pessoa e holismo no estudo empírico "Nutritional adaptation of women living with HIV: a pilot study", publicado na revista Holistic Nursing Practice, em 1997. Criticamente, a interpretação do termo pessoa se deu pela compreensão do ser enquanto um ser ôntico-ontológico, como forma de percepção verdadeira do sentido do ser (pessoa, como uma estrutura universal vivente em um mundo antropológico e social, ao qual mulheres com HIV podem se adaptar ao novo estilo de vida e receber atenção integral da enfermagem, principalmente no que concerne ao aspecto nutricional.

  2. Sepse tardia em pré-termos de uma unidade de terapia intensiva neonatal: análise de três anos

    Directory of Open Access Journals (Sweden)

    Brunnella Alcantara Chagas de Freitas

    2012-03-01

    Full Text Available OBJETIVO: Avaliar a prevalência, os fatores e os agentes etiológicos associados à sepse neonatal tardia em pré-termos de uma unidade de terapia intensiva neonatal. MÉTODOS: Estudo transversal, de dados secundários de prontuários de pré-termos admitidos em uma unidade de terapia intensiva neonatal, no triênio 2008-2010. Caracterizou-se a variável desfecho sepse neonatal tardia pelos critérios da Agência Nacional de Vigilância Sanitária. Empregaram-se os testes do Qui-quadrado de Pearson, exato de Fisher ou Qui-quadrado de tendência linear para as variáveis qualitativas. Considerou-se significante p<0,05. Realizaram-se análises bivariadas e multivariadas entre as variáveis independentes e a dependente, obtendo-se como medida de efeito as razões de prevalências, considerando-se p<0,20. RESULTADOS: Participaram do estudo 267 prematuros. Destes, 28,5% evoluíram com sepse tardia, com positividade de hemocultura em 17,1%. Evoluíram a óbito 8,2% dos pré-termos e, destes, 68,2% eram do grupo sepse. Associaram-se à hemocultura positiva três óbitos, todos com a participação de Gram-negativos. Na análise bivariada para o desfecho sepse tardia observou-se que, à medida que decresceram a idade gestacional e o peso ao nascer, houve aumento de sua prevalência. A duração de ventilação mecânica e de cateter central de inserção periférica por períodos iguais ou superiores respectivamente a 10 e 11 dias se associaram ao desfecho sepse neonatal tardia em 80,8% e 76,2% dos pré-termos. Na análise multivariada, permaneceu como fator associado à sepse tardia o tempo de cateter central de inserção periférica igual ou superior a 11 dias. Houve maior participação dos Gram-negativos como agentes etiológicos, sendo mais frequentes a Klebsiella pneumoniae e a Escherichia coli. CONCLUSÕES: A sepse tardia mantém-se uma preocupação por sua prevalência nas unidades de terapia intensiva e pela associação a procedimentos

  3. Cognição, atenção, temperamento e comportamento em crianças nascidas pré-termo na fase pré-escolar

    OpenAIRE

    Fabíola Dantas Andrez Nobre Arantes de Carvalho

    2015-01-01

    O nascimento pré-termo aumenta o risco para problemas no desenvolvimento. O estudo teve por objetivos: a) examinar as associações entre condições clínicas neonatais e indicadores de cognição, atenção, temperamento e comportamento de crianças nascidas pré-termo; b) comparar esses indicadores em grupos estratificados pelo nível de prematuridade. A amostra foi composta por 50 crianças nascidas pré-termo (idade gestacional média = 31 semanas [26-35] e com peso ao nascimento médio de 1.190g [650-1...

  4. PROCESSAMENTO SENSORIAL NO PERÍODO DA INFÂNCIA EM CRIANÇAS NASCIDAS PRÉ-TERMO: REVISÃO SISTEMÁTICA

    Directory of Open Access Journals (Sweden)

    Ana Carolina Cabral de Paula Machado

    Full Text Available RESUMO Objetivo: Buscar sistematicamente evidências fundamentadas e de qualidade sobre o processamento sensorial em crianças nascidas pré-termo no período da infância. Fontes de dados: A busca da literatura disponível sobre o tema foi realizada nas bases de dados eletrônicas Sistema Online de Busca e Análise de Literatura Médica (Medline/PubMed, Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs/Biblioteca Virtual em Saúde (BVS, Índice Bibliográfico Español de Ciencias de la Salud (IBECS/BVS, Scopus e Web of Science. Foram incluídos estudos indexados, originais, quantitativos e disponíveis na íntegra em meio digital, publicados em português, inglês ou espanhol, entre 2005 e 2015, envolvendo crianças entre zero e 9 anos de idade. Síntese dos dados: A busca identificou 581 artigos, e oito foram incluídos conforme critérios de elegibilidade. Destes, seis estudos (75% encontraram alta frequência de processamento sensorial alterado em crianças pré-termo. A associação entre processamento sensorial e desfechos de desenvolvimento foi observada em três estudos (37,5%. Verificou-se associação entre processamento sensorial e características neonatais em cinco estudos (62,5%. Os resultados de processamento sensorial frequentemente se associam a idade gestacional, sexo masculino e lesões da substância branca. Conclusões: Análise da literatura atual sugere que prematuridade tem impacto negativo no processamento sensorial. Idade gestacional, sexo masculino e lesões de substância branca aparecem como fatores de risco para alterações de processamento sensorial em crianças nascidas pré-termo. O prejuízo na capacidade de receber informações sensoriais, de integrar e de adaptar-se a elas parece interferir negativamente no desenvolvimento motor, cognitivo e de linguagem dessas crianças. Destaca-se a viabilidade da identificação das alterações de processamento sensorial nos primeiros anos de vida

  5. Termo do 1º Consenso em Disfunção Temporomandibular e Dor Orofacial Statement of the 1st Consensus on Temporomandibular Disorders and Orofacial Pain

    Directory of Open Access Journals (Sweden)

    Simone Vieira Carrara

    2010-06-01

    Full Text Available O Termo do 1º Consenso em Disfunção Temporomandibular e Dor Orofacial* foi criado com o propósito de substituir divergências por evidência científica dentro dessa especialidade da Odontologia. O documento oferece informações claras e fundamentadas para orientar o cirurgião-dentista e demais profissionais de saúde sobre os cuidados demandados pelo paciente, tanto no processo de diagnóstico diferencial quanto na fase de aplicação das terapias de controle da dor e disfunção. O Termo foi aprovado no mês de janeiro de 2010 em reunião realizada durante o Congresso Internacional de Odontologia do Estado de São Paulo e converge o pensamento dos profissionais mais conceituados do Brasil na especialidade Disfunção Temporomandibular e Dor Orofacial.This Statement of the 1st Consensus on Temporomandibular Disorders and Orofacial Pain was created with the purpose of substituting controversies for scientific evidence within this specialty field of dentistry. The document provides clear and well-grounded guidance to dentists and other health professionals about the care required by patients both in the process of differential diagnosis and during the stage when they undergo treatment to control pain and dysfunction. The Statement was approved in January 2010 at a meeting held during the International Dental Congress of São Paulo and draws together the views of Brazil's most respected professionals in the specialty of Temporomandibular Disorders and Orofacial Pain.

  6. Estudo das variações dos níveis de retinol no colostro humano de parturientes a termo e pré-termo Study of retinol level variations of human colostrum among parturient women with term and pre-term newborns

    Directory of Open Access Journals (Sweden)

    Illana Louise Pereira de Melo

    2004-09-01

    Full Text Available OBJETIVOS: analisar as variações dos níveis de retinol no colostro de parturientes a termo e pré-termo. MÉTODOS: foram analisadas amostras de leite de 78 lactantes, sendo metade delas mães de recém-nascidos prematuros. As amostras de colostro foram obtidas por expressão manual de uma mama, até 72 horas após o parto, no turno vespertino e no início da mamada, até atingir um volume de 2,0 ml. A determinação do retinol foi realizada por cromatografia líquida de alta eficiência e os resultados foram submetidos à análise estatística através do teste t de Student. RESULTADOS: o valor médio do retinol no colostro de mães a termo (n = 39 e pré-termo (n = 39 foram, respectivamente, 89,4 ± 46,1 mig/dL e 55,6 ± 27,7 mig/dL. A diferença entre as médias foi estatisticamente significante (p OBJECTIVES: to analyze retinol levels variations in the colostrum of term and pre-term parturient women. METHODS: colostrum samples of 78 lactating women, half of which were mothers of premature newborns, were analyzed. The samples were manually extracted from one breast until 2.0 ml were obtained. They were collected up to 72 hours after birth, during the morning hours and right before nursing. Retinol levels were determined by high-performance liquid chromatography and analyzed by the T-test for means comparison. RESULTS: the mean retinol values in the colostrums of women with term (n = 39 and pre-term newborns (n = 39 were 89,4 ± 46,1 mug/dL and 55,6 ± 27,7 mug/dL, respectively. The difference of means was considered statistically significant at (p < 0,001. Human milk meets the need for Vitamin A in the term newborn. However, for the premature newborn, it only supplied 66% of the needs. CONCLUSIONS: results suggest that exclusive use of human milk does not meet the needs of pre-term newborn completely and that a Vitamin A supplement for the mother is necessary in order to reduce Vitamin A risk deficiency.

  7. Helium crystals

    International Nuclear Information System (INIS)

    Lipson, S.G.

    1987-01-01

    Hexagonal close-packed helium crystals in equilibrium with superfluid have been found to be one of the few systems in which an anisotropic solid comes into true thermodynamic equilibrium with its melt. The discovery of roughening transitions at the liquid-solid interface have shown this system to be ideal for the study of the statistical mechanics of interface structures. We describe the effect of roughening on the shape and growth of macroscopic crystals from both the theoretical and experimental points of view. (author)

  8. Ruptura prematura das membranas amnióticas no pré-termo: fatores associados à displasia broncopulmonar Preterm premature rupture of the fetal membranes: factors associated with bronchopulmonary dysplasia

    OpenAIRE

    Danieli Dias Gonçalves; Luiz Guilherme Pessoa da Silva; Glaucio de Moraes Paula; Olga Bonfim; Maria Elizabeth Lopes Moreira; Augusta Maria Batista Assumpção; Valéria Seild Figueira

    2010-01-01

    OBJETIVO: identificar os fatores obstétricos e neonatais associados ao desfecho de displasia broncopulmonar em pacientes com amniorrexe prematura no pré-termo. MÉTODOS: foram analisados 213 prontuários do Instituto Fernandes Figueira, entre 1998 e 2002, cujas pacientes evoluíram com quadro de amniorrexe prematura

  9. Desenvolvimento motor de crianças pré-termo moderadas aos sete e oito anos de idade Motor development of moderate preterm children at seven and eight years of age

    Directory of Open Access Journals (Sweden)

    Ana Cristina Resende Camargos

    2011-06-01

    Full Text Available Crianças pré-termo podem apresentar distúrbios leves do desenvolvimento motor, que podem ser imperceptíveis até a idade pré-escolar ou escolar. O objetivo desse estudo foi comparar o desenvolvimento motor de crianças pré-termo moderadas com crianças a termo aos sete e oito anos de idade. Foram coletados dados de 13 crianças pré-termo e 13 crianças a termo de uma escola da rede municipal de Betim. Foi utilizada a Escala de Desenvolvimento Motor para avaliar motricidade fina, motricidade global, equilíbrio, esquema corporal, organização espacial e organização temporal, bem como a idade motora geral e o quociente motor geral. O teste Mann-Whitney foi utilizado para comparar as idades motoras e os quocientes motores entre os grupos. Foi encontrada diferença significativa somente nos valores da motricidade fina entre os grupos (p=0,01, sendo que o grupo pré-termo apresentou desempenho inferior. Dessa forma, crianças pré-termo moderadas que não apresentam características de alto risco biológico ao nascimento também podem necessitar de acompanhamento ambulatorial até a idade escolar.Preterm children may have light motor developmental impairments, which may be imperceptible until pre-school age or even school age. The aim of this study was to compare the motor development of moderate preterm children with full-term ones at seven and eight years of age. Data from 13 preterm and 13 full-term children were collected from a public school in Betim-MG. The Motor Development Scale was used to access fine and global motricity, balance, body scheme, spatial organization, time organization, as well as general motor age and general motor quotient. The Mann-Whitney's Test was used to compare the motor ages and motor quotients between the groups. A significant difference was only found in the fine motricity values between the groups (p=0.01, the preterm group having shown a poorer performance. Therefore, moderate preterm children who do not

  10. Determinação dos valores hematológicos e das concentrações séricas de ferro e ferritina em sangue de cordão umbilical de recém-nascidos de termo e pré-termo no Hospital Israelita Albert Einstein de São Paulo

    Directory of Open Access Journals (Sweden)

    Silber Marcelo

    2000-01-01

    Full Text Available Determinaram-se os valores hematológicos (Hb, Ht, VCM, HCM, CHCM, reticulócitos e as concentrações séricas de ferro e ferritina no sangue de cordão umbilical de recém-nascidos (RN no Hospital Albert Einstein. A amostra continha 32 RN de termo (T e 30 RN pré-termo (PT. Os RN apresentavam-se clinicamente sadios, sendo excluídos os que apresentaram intercorrências clínicas ou no momento do parto. O sangue foi colhido por punção da veia umbilical até 5 minutos após a dequitação e encaminhado ao laboratório de patologia clínica para processamento laboratorial. Os valores hematológicos encontram-se mais elevados no grupo de RNT em relação ao grupo de RNPT (p<0,05. Ajustando-se um modelo de regressão logística múltipla, o Ht tem valor preditivo para a prematuridade, observando-se uma relação inversamente proporcional entre o valor do Ht e a idade gestacional.

  11. Tempo de aleitamento materno exclusivo em recém-nascidos prematuros e a termo Time of exclusive breastfeeding of preterm and term newborn babies

    Directory of Open Access Journals (Sweden)

    Waléria Ferreira da Silva

    2012-01-01

    Full Text Available OBJETIVOS: determinar o tempo de aleitamento materno exclusivo de recém nascidos prematuros e observar se estes apresentam um índice de aleitamento materno exclusivo diferente do apresentado pelo município de Maceió, na I e II Pesquisa de Prevalência de Aleitamento Materno nas Capitais Brasileiras e no Distrito Federal. Além de comparar o tempo de aleitamento materno e aleitamento materno exclusivo de recém nascidos prematuros e a termo e verificar as causas do desmame precoce e suas consequências. MÉTODO: trata-se de uma investigação de campo, de caráter exploratório e longitudinal da prevalência do aleitamento materno exclusivo de recém nascidos prematuro e à termo. RESULTADOS: o percentual de aleitamento materno e de aleitamento materno exclusivo de prematuros aos 6 meses. Houve diferença significante para a variável peso ao nascimento. Dentre as causas do desmame precoce, os fatores educacionais seguidos dos fatores culturais apareceram em maior porcentagem. Como consequência do desmame precoce a prática de hábitos orais ocorreu em 98,1% das crianças. CONCLUSÃO: as crianças prematuras permaneceram mais tempo em aleitamento materno e em aleitamento materno exclusivo que as nascidas a termo. Os fatores educacionais e culturais foram as principais causas do desmame precoce e sua consequência foi o uso de chupeta e mamadeira.PURPOSE: to determine the benefits of exclusive breastfeeding. However, only a minority of women engage in breastfeeding practices. This research is aimed to establish the time of exclusive breastfeeding as for preterm babies and observe whether they have a different level of exclusive breastfeeding in relation to the level achieved by the city of Maceió at the I and II PPAM-CDF. Additionally, other goals are to compare the breastfeeding and exclusive breastfeeding types of preterm and term newborns and determine the causes of early weaning and its consequences. METHOD: this is a field investigation

  12. Tempo de aleitamento materno exclusivo em recém-nascidos prematuros e a termo Time of exclusive breastfeeding of preterm and term newborn babies

    Directory of Open Access Journals (Sweden)

    Waléria Ferreira da Silva

    2013-02-01

    Full Text Available OBJETIVOS: determinar o tempo de aleitamento materno exclusivo de recém nascidos prematuros e observar se estes apresentam um índice de aleitamento materno exclusivo diferente do apresentado pelo município de Maceió, na I e II Pesquisa de Prevalência de Aleitamento Materno nas Capitais Brasileiras e no Distrito Federal. Além de comparar o tempo de aleitamento materno e aleitamento materno exclusivo de recém nascidos prematuros e a termo e verificar as causas do desmame precoce e suas consequências. MÉTODO: trata-se de uma investigação de campo, de caráter exploratório e longitudinal da prevalência do aleitamento materno exclusivo de recém nascidos prematuro e à termo. RESULTADOS: o percentual de aleitamento materno e de aleitamento materno exclusivo de prematuros aos 6 meses. Houve diferença significante para a variável peso ao nascimento. Dentre as causas do desmame precoce, os fatores educacionais seguidos dos fatores culturais apareceram em maior porcentagem. Como consequência do desmame precoce a prática de hábitos orais ocorreu em 98,1% das crianças. CONCLUSÃO: as crianças prematuras permaneceram mais tempo em aleitamento materno e em aleitamento materno exclusivo que as nascidas a termo. Os fatores educacionais e culturais foram as principais causas do desmame precoce e sua consequência foi o uso de chupeta e mamadeira.PURPOSE: to determine the benefits of exclusive breastfeeding. However, only a minority of women engage in breastfeeding practices. This research is aimed to establish the time of exclusive breastfeeding as for preterm babies and observe whether they have a different level of exclusive breastfeeding in relation to the level achieved by the city of Maceió at the I and II PPAM-CDF. Additionally, other goals are to compare the breastfeeding and exclusive breastfeeding types of preterm and term newborns and determine the causes of early weaning and its consequences. METHOD: this is a field investigation

  13. Como tornar os termos de consentimento mais fáceis de ler? How to make consent forms easier to read?

    Directory of Open Access Journals (Sweden)

    Diego Vinicius Pacheco de Araujo

    2010-01-01

    Full Text Available OBJETIVO: Reconhecer o nível de alfabetismo funcional de usuários do ambulatório do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCMFUSP com a finalidade de identificar recomendações para adequar a redação do TCLE ao nível de alfabetismo dos usuários, pois estes podem vir a ser sujeitos de pesquisa. MÉTODOS: Estudo transversal quantitativo com 399 sujeitos. A amostra foi intencional, selecionada entre usuários dos ambulatórios do HCFMUSP. A coleta de dados utilizou instrumento que continha um texto em prosa compatível para a avaliação das habilidades de leitura necessárias para a compreensão de um TCLE. RESULTADOS: Mais de 46,6% dos entrevistados foram classificados como analfabetos funcionais. Desses, 12,7% sequer foram capazes de entender a tarefa proposta no texto lido. Apesar disto, quase 50% dos entrevistados declararam ter ao menos iniciado o ensino médio. CONCLUSÃO: Os resultados e as orientações para a redação de texto centrada no leitor permitiu que elaborássemos recomendações para tornar os termos de consentimento mais fáceis de ler. Recomendamos que o pesquisador elabore o TCLE como um texto em estrutura narrativa, dirigido ao leitor, usando palavras e termos familiares, ou seja, termos comuns à linguagem dos sujeitos e à linguagem médica. Além de contribuir para melhorar a relação entre o sujeito e o pesquisador, acredita-se que estas recomendações possam contribuir para a diminuição do tempo de tramitação de projetos de pesquisa. Já que os problemas na redação do TCLE motivam boa parte das pendências que retardam este andamento.OBJECTIVE: Define the literacy level of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCMFUSP outpatients, for the purpose of identifying recommendations to adapt writing of the informed consent form to the outpatients literacy level, since these can become the subject of research. METHODS

  14. Magnetophotonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Fujikawa, R [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Baryshev, A [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Khanikaev, A [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Lim, P B [CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan (Japan); Uchida, H [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Aktsipetrov, O [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Fedyanin, A [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Murzina, T [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Granovsky, A [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation)

    2006-04-21

    When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs. (topical review)

  15. Magnetophotonic crystals

    International Nuclear Information System (INIS)

    Inoue, M; Fujikawa, R; Baryshev, A; Khanikaev, A; Lim, P B; Uchida, H; Aktsipetrov, O; Fedyanin, A; Murzina, T; Granovsky, A

    2006-01-01

    When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs. (topical review)

  16. INFLUÊNCIA DAS FLORESTAS URBANAS NA VARIAÇÃO TERMO-HIGROMÉTRICA DA ÁREA INTRAURBANA DE CURITIBA – PR

    Directory of Open Access Journals (Sweden)

    Luciana Leal

    2014-12-01

    Full Text Available De modo a entender a influência das florestas urbanas na variação termo-higrométrica da área intraurbana da cidade de Curitiba, este trabalho teve como objetivo analisar a variação temporal e espacial da temperatura e da umidade relativa do ar em cada estação do ano e relacioná-la com a presença das florestas urbanas. Para a coleta dos dados meteorológicos foram estabelecidos 44 pontos de monitoramento em quatro transectos na malha urbana da cidade. Nestes pontos foram instalados miniabrigos meteorológicos com sensores modelo Hobo®, fixados nas hastes de sinaleiros e placas de sinalização. O monitoramento da temperatura e umidade relativa do ar foi realizado em períodos correspondentes às quatro estações do ano, com 22 dias de coleta e registro contínuo de dados em intervalos de 15 minutos. Nos quatro transectos analisados na área intraurbana de Curitiba foram encontradas diferenças termo-higrométricas significativas entre os pontos de monitoramento em todos os períodos analisados. Mesmo nas estações do ano de mais baixas temperaturas, o outono e o inverno, foram encontradas diferenças térmicas, relacionadas ao calor antropogênico. Pela análise do perfil longitudinal das temperaturas, observou-se curva semelhante ao perfil clássico das ilhas de calor urbano, com as maiores temperaturas nos locais com maior intensidade de ocupação e atividades antrópicas, como na área central e região centro-sul. As menores temperaturas foram encontradas em bairros residenciais e periféricos, como nas porções norte e noroeste do município e limite sul, além de se evidenciar o efeito do resfriamento das florestas urbanas presentes na área intraurbana, como os Parques Municipais Barigui e São Lourenço. As regiões com maior quantidade de áreas permeáveis, concentração de remanescentes florestais ou espaços verdes públicos apresentaram menores temperaturas e aumento da umidade relativa do ar.

  17. Postural control of small for gestational age infants born at term Controle postural de lactentes nascidos a termo pequenos para a idade gestacional

    Directory of Open Access Journals (Sweden)

    D Campos

    2007-02-01

    Full Text Available OBJECTIVE: This study compared the postural control of small (SGA and appropriate (AGA for gestational age infants born at term, at the ages of 3, 6, 9 and 12 months. METHOD: This was a cohort study of infants born at term, with birth weight less than the 10th percentile for the SGA group and between the 10th and 90th percentiles for the AGA group. Infants with genetic syndromes, malformations, congenital infections and internment in neonatal intensive care unit were excluded. The evaluation instrument was the Alberta Infant Motor Scale. RESULTS: Comparison of the SGA and AGA groups did not show any significant differences (p>0.05 at the assessment times. However, the postural control of the SGA group was influenced by the gestational age (r=-0.83; p= 0.006 and 5th minute Apgar (r= 0.79; p= 0.01 in the 3rd month, and by maternal occupation (r= 0.67; p= 0.01 in the 6th month. CONCLUSION: It was concluded that the postural control was similar in the groups. However, the postural control of the SGA group was influenced by biological and environmental factors.OBJETIVO: Este estudo teve por objetivo comparar o controle postural de lactentes nascidos a termo, pequenos (PIG e adequados para a idade gestacional (AIG nos 3º, 6º, 9º e 12º meses. MÉTODO: Estudo longitudinal de lactentes nascidos a termo, com peso de nascimento menor que o percentil 10 para o grupo PIG e entre o percentil 10 e 90 para o grupo AIG. Síndromes genéticas, más-formações, infecções congênitas e internados em unidade de terapia intensiva neonatal foram excluídos. O instrumento de avaliação foi Alberta Infant Motor Scale. RESULTADOS: A comparação do grupo PIG e AIG não mostrou diferença significativa (p> 0,05 nos meses avaliados. Entretanto, o controle postural do grupo PIG foi influenciado pela idade gestacional (r= -0,83/p= 0,006 e Apgar de 5' (r= 0,79/p= 0,01 no 3º mês; e pela ocupação materna (r= 0,67/p= 0,01 no 6º mês. CONCLUSÃO: Concluiu-se que o

  18. Comportamento e estrutura a termo da volatilidade de empresas de grande e pequeno porte Behavior and term structure of volatility for large and small companies

    Directory of Open Access Journals (Sweden)

    Pablo Rogers

    2008-01-01

    Full Text Available Em contraposição às hipóteses para sustentação dos modelos financeiros "clássicos", como o Capital Asset Pricing Model (CAPM de Sharpe-Litner-Mossin, a literatura recente de Finanças tem documentado que algumas características das empresas se mostram relevantes para explicar retornos esperados. Este artigo tem por objetivo analisar se o tamanho da empresa no Brasil é uma característica importante para explicar uma outra dimensão da relação risco versus retorno: a volatilidade. Como metodologia, procedeu-se a uma reestruturação completa do índice IBrX da Bolsa de Valores de São Paulo (Bovespa, obtendo-se dois novos índices: um de empresas com grande porte e outro de empresas com pequeno porte. A partir dos índices construídos, analisaram-se o comportamento e a estrutura a termo da volatilidade, com ajustes dos modelos GARCH (1,1 e TARCH (1,1. Em linhas gerais, pode-se concluir que o comportamento e a estrutura a termo da volatilidade de empresas de grande e pequeno porte são diferentes, o que permite a incorporação da característica tamanho da empresa nas funções financeiras, tais como decisões de investimentos, precificação de títulos e gerenciamento de risco.Recent finance literature states that certain company characteristics are relevant to explain the returns expected, which is contrary to classic financial models such as the Capital Asset Pricing Model. The effect of company size in Brazil was investigated to verify if it explains another aspect of the relationship of risk versus return, which is volatility. The method used was to restructure the IBrX index (Sao Paulo Stock Exchange - Bovespa to obtain a new index for large sized companies and also another for small companies. The behavior and term structure of volatility was analyzed using adjustments of the GARCH (1.1 and TARCH (1.1 models for each of the two new indices. It was concluded that, in general, small and large companies have different behaviors

  19. Desenvolvimento psicológico na fase escolar de crianças nascidas pré-termo em comparação com crianças nascidas a termo Psychological development of school-age children born preterm in comparison with children born full-term

    Directory of Open Access Journals (Sweden)

    Maria Beatriz Martins Linhares

    2005-04-01

    Full Text Available O presente estudo objetivou avaliar indicadores do desenvolvimento psicológico na fase escolar de crianças nascidas pré-termo com muito baixo peso e compará-los aos de crianças nascidas a termo, quanto às áreas intelectual, emocional e comportamental. A amostra foi composta por 40 crianças de 8 a 10 anos, subdivididas em 2 grupos: Pré-termo (PT, 20 crianças nascidas 2.500g. Foram utilizados o Raven, o Desenho da Figura Humana e a Escala Comportamental Infantil. As crianças PT apresentaram mais freqüentemente nível intelectual inferior à média e problemas comportamentais em comparação às AT. Não houve diferença entre os grupos quanto aos aspectos emocionais. Os problemas de enurese, medo, tiques, impaciência e dificuldade de permanência nas atividades foram significativamente mais freqüentes no PT do que no AT. Verificou-se que, no grupo PT, quanto menor o nível intelectual das crianças, mais problemas de comportamento elas apresentavam.The present study aims to assess psychological development in terms of behavioral, intellectual and emotional indicators of preterm and very low birthweight children at school age in comparison with full-term children. The sample in this study consisted of forty children aged from 8 to 10 years. They were divided into 2 groups: Preterm (PT consisting of 20 children born 2.500g birthweight. Raven's Special Scale, Draw-a-Person and Child Behavior Scale were used in the psychological assessment. PT group presented more behavioral problems and lower intellectual level when compared to the FT group. Enuresis, fear, tics, impatience and lack of focus on activities were significantly more frequent in the PT group than in the FT group. In the PT group the lower the intellectual level of the children the more behavior problems they presented.

  20. “ÁGUA VIRA SAL LÁ NA SALINA”: O GLOSSÁRIO DOS TERMOS DO SAL NO RIO GRANDE DO NORTE NUMA PERSPECTIVA SOCIOTERMINOLÓGICA

    Directory of Open Access Journals (Sweden)

    Moisés Batista da Silva

    2016-01-01

    Full Text Available O presente trabalho tem como objetivo apresentarresultados da pesquisa sobre os termos usados na Indústriado sal, em três municípios que fazem parte da região salineirado Rio Grande do Norte. Primeiramente, abordamosas diferentes ciências do Léxico estudadas por Boutin--Quesnel (1985, Barbosa (1994,1995, Barros (2004,dando ênfase maior nas orientações teórico-metodológicasda Socioterminologia (FAULSTICH, 1995, 1996, 1998,2006. Em seguida, expomos os procedimentos tanto dametodologia de campo quanto da metodologia da organizaçãodo Glossário da Terminologia do Sal - GLOSSAL(SILVA, 2007. Depois, apresentamos uma amostra dosverbetes, as análises feitas a partir desse repertório e, porfim, as considerações finais quanto aos fatos linguísticos,observados nesse glossário. Desse modo, essa pesquisa sejustifica por possibilitar a divulgação de um produto terminográficodestinado, não só aos especialistas e pesquisadoresdas Ciências do Léxico, como também ao grandepúblico e aos interessados em aprofundar seus estudos naterminologia do sal.Palavras-chave: Sal. Indústria do Sal. Terminologia. Socioterminologia.Glossário.

  1. Comparação entre a frequência de positividade do questionário T-ACE entre mães de recém-nascidos de termo e prematuros

    Directory of Open Access Journals (Sweden)

    Inês Maria Crespo Gutierrez Pardo

    2013-12-01

    Full Text Available Objetivos: os objetivos deste estudo foram verificar a frequência de positividade do T-ACE questionário durante a gravidez de mães de recém-nascidos prematuros comparados com as de termo, e avaliar a associação de álcool referido pelo teste com o tabagismo materno e paterno. Métodos: estudo tipo observacional, transversal, com recrutamento de forma sequencial de 142 puérperas de uma maternidade pública. Foram aplicados: entrevista para coleta de dados clínicos e sociodemográficos e T-ACE questionário. Os recém-nascidos de termo e prematuros destas mulheres foram avaliados em relação ao peso, comprimento e perímetro cefálico ao nascimento. Estudo aprovado pelo comitê de Ética local e a participação das mulheres foi mediante assinatura do termo de consentimento livre e esclarecido. A análise dos dados foi realizada usando o programa SPSS, sendo adotado nível de significância de 5%. Resultados: das puérperas entrevistadas 21,1% foram consideradas consumidoras de álcool pelo T-ACE questionário. Quando divididas entre puérperas de partos de termo e prematuros, encontraram-se 21% de positividade do T-ACE teste no grupo de termo e 21,3% no grupo dos prematuros (p = 0,98. Houve importante associação entre positividade do T-ACE questionário e tabagismo materno e paterno durante a gestação (p = 0,04. Conclusões: cerca de duas em cada dez gestantes apresentaram teste T-ACE positivo, sem diferença entre o grupo de parto de termo e prematuros. A associação encontrada entre o consumo de álcool e fumo durante a gravidez sugere a importância do rastreamento rotineiro do T-ACE questionário, tendo em vista que esses dois agentes potencializam efeitos adversos no feto.

  2. Photonic time crystals.

    Science.gov (United States)

    Zeng, Lunwu; Xu, Jin; Wang, Chengen; Zhang, Jianhua; Zhao, Yuting; Zeng, Jing; Song, Runxia

    2017-12-07

    When space (time) translation symmetry is spontaneously broken, the space crystal (time crystal) forms; when permittivity and permeability periodically vary with space (time), the photonic crystal (photonic time crystal) forms. We proposed the concept of photonic time crystal and rewritten the Maxwell's equations. Utilizing Finite Difference Time Domain (FDTD) method, we simulated electromagnetic wave propagation in photonic time crystal and photonic space-time crystal, the simulation results show that more intensive scatter fields can obtained in photonic time crystal and photonic space-time crystal.

  3. Adaptação transcultural da tradução para o português de termos incluídos na CIPE® e identificados no projeto CIPESC

    Directory of Open Access Journals (Sweden)

    Maria Miriam Lima da Nóbrega

    2002-12-01

    Full Text Available Os sistemas de classificação em enfermagem têm contribuído para delimitar nosso campo de atuação, identificando conceitos que fazem parte de nossa linguagem profissional e promovendo o conhecimento acerca de seus ignificados. Neste trabalho, relata-se o processo de adaptação transcultural de 145 termos identificados no projeto CIPESC e já incluídos no eixo Foco da prática da Classificação de Fenômenos de Enfermagem da CIPE® - versão Beta, através da comparação entre a tradução destes termos para o português do Brasil e sua tradução realizada para o português de Portugal, tendo o texto original em inglês como base de comparação.

  4. Estudo de termos simples, expressões fixas e semifixas encontrados em corpora paralelos e comparáveis da subárea de economia política

    Directory of Open Access Journals (Sweden)

    Talita Serpa

    2014-01-01

    Full Text Available O principal objetivo deste trabalho é analisar os termos simples, expressões fixas e semifixas mais frequentes da subárea de Economia Política em português e seus correspondentes em inglês, extraídos de quinze artigos escritos pelo economista Bresser-Pereira, e de suas respectivas autotraduções. A metodologia utilizada fundamenta-se nos Estudos da Tradução Baseados em Corpus (Baker, 1992, 1993, 1995, 1996; Camargo, 2005, 2007, na Linguística de Corpus (Berber Sardinha, 2004 e na Teminologia (Barros, 2004. Notamos que termos e expressões empregados nos textos fonte não apresentam univocidade dentro da língua de especialidade referente às Ciências Sociais brasileiras. Os termos traduzidos para o inglês também refletem variação devido às opções adotadas pelo autotradutor ao procurar adequar os conceitos teóricos às possibilidades da Língua Meta.

  5. Validação das definições de termos identificados no projeto CIPESC para o eixo foco da prática de enfermagem da CIPE®

    Directory of Open Access Journals (Sweden)

    Telma Ribeiro Garcia

    2002-02-01

    Full Text Available Em continuidade à contribuição da Enfermagem brasileira para a elaboração da CIPEâ, que está sendo construída sob a coordenação do CIE, objetivou-se neste trabalho definir os termos identificados no projeto CIPESC e classificados no eixo foco da prática de enfermagem da Classificação de Fenômenos de Enfermagem da CIPE® - versão Beta e validar essas definições junto a um grupo de juízes composto por profissionais com envolvimento anterior na execução do projeto CIPESC, ou com envolvimento docente ou assistencial na área de Enfermagem em Saúde Coletiva. O processo foi realizado em duas fases, considerando-se validadas as definições que alcançaram um índice de Concordância (IC³ 0,80 entre o grupo de juízes. Noventa e nove definições de termos foram validadas: 26 alcançaram IC igual a 1,00; 56 alcançaram IC entre 0,90 e 0,99 e 17 alcançaram IC entre 0,80 e 0,89. A definição de um termo não foi validada.

  6. Termo de consentimento e análise de material biológico armazenado Consent procedures and research on stored biological samples

    Directory of Open Access Journals (Sweden)

    Cristiano Guedes Duque

    2010-01-01

    Full Text Available OBJETIVO: Relatar uma experiência envolvendo a obtenção de termo de consentimento livre e esclarecido (TCLE para estudo retrospectivo realizado no Instituto Nacional de Câncer (INCA. O mesmo envolvia a revisão de prontuários e a análise de blocos de parafina de pacientes com câncer de cólon operados entre 2000 e 2004. Respeitando a resolução 196/96 do Conselho Nacional de Saúde e a determinação do Comitê de Ética em Pesquisa (CEP do INCA, buscou-se obter o consentimento informado. MÉTODOS: Nas consultas agendadas, conseguiu-se aplicar o termo a apenas quatro pacientes, durante três meses. Foram enviadas então pelo correio duas cópias do TCLE, juntamente com um sumário e um envelope selado para o re-envio aos pesquisadores. Antes da postagem, tentou-se contato telefônico. RESULTADOS: Obteve-se retorno de 115 dos 155 TCLE enviados (74%. Dentre as respostas recebidas, 111 consentiram participar do estudo, houve uma recusa e foi informado que três pacientes haviam falecido. O tempo entre o envio da correspondência e o recebimento da resposta variou entre 2 e 89 dias (mediana: 10 dias. Houve sucesso no contato telefônico com 60 dos 160 pacientes (37,5%. Para os que já haviam falecido e para os que não retornaram o TCLE, o CEP aprovou a dispensa do mesmo. O custo final do envio dos envelopes foi de R$1.004,40. CONCLUSÃO: A busca de comunicação telefônica e postal com pacientes para a obtenção de TCLE de estudo clínico retrospectivo é factível. A maioria respondeu ao contato e consentiu participar. Há, porém, custos e riscos agregados que não podem ser desprezados.OBJECTIVE: To present practical experience in obtaining consent form (CF for a study performed at the "Instituto Nacional de Câncer" involving research on stored biologic samples from patients operated for colon cancer from 2000 to 2004. According to the Brazilian National Health Council resolution nº196/96, researchers must make every effort to obtain

  7. Photonic Crystal Fibers

    National Research Council Canada - National Science Library

    Kristiansen, Rene E

    2005-01-01

    This report results from a contract tasking Crystal Fibre A/S as follows: Crystal Fibre will conduct research and development of large mode area, dual clad multi-core Yb-doped photonic crystal fiber...

  8. Alimentação do recém-nascido pré-termo: aleitamento materno, copo e mamadeira Feeding preterm infants: breast, cup and bottle

    Directory of Open Access Journals (Sweden)

    Andréa Monteiro Correia Medeiros

    2011-03-01

    Full Text Available OBJETIVO: Verificar a oferta de seio materno em bebês nascidos pré-termos, internados na Unidade de Terapia Intensiva do Hospital e Maternidade Neomater, relacionando este dado com a forma de oferecer a dieta (copo ou mamadeira, na ausência da mãe, e a estimulação fonoaudiológica realizada. MÉTODOS: Participaram 48 recém-nascidos prematuros, com idade gestacional inferior ou igual a 36 6/7 semanas, com peso PURPOSE: To assess the offer of the maternal breast in preterm babies hospitalized at the Intensive Care Unit of the Hospital and Maternity Neomater, linking this datum with the manner to feed them (cup or bottle in the absence of the mother, and the speech-language stimulation carried out. METHODS: Forty-eight newborn preterm infants with gestational age less than or equal to 36 6/7 weeks, weighting <2500 grams and with stable respiratory pattern participated in this study. The newborns were divided into two groups: group A (35 newborns with bottle feeding, and group B (13 newborns with cup feeding. Speech-Language Pathology monitoring was organized in Stage 1 (non-nutritive sucking in "gloved finger" or "empty breast" concomitant with enteral feeding; Stage 2 (oral feeding offer - maternal breast, bottle or cup - with complement provided by enteral feeding; Stage 3 (exclusive oral feeding offer - maternal breast, bottle or cup; Stage 4 (effective breastfeeding offer. A comparison was carried out between the groups regarding the number of days in each phase. Data were statistically analyzed using the independent t-test, with significance level of 5%. RESULTS: There were no significant differences between the groups for any of the studied parameters. Breast feeding was equally accepted by newborns in the cup and the bottle groups. CONCLUSION: Breast feeding can be equally accepted, regardless the alternative feeding form used (cup or bottle, provided that there is adequate Speech-Language Pathology monitoring and encouragement to

  9. Computer simulation of thermal-hydraulic transient events in multi-circuits with multipumps; Simulacao computacional de eventos termo-hidraulicos transitorios em multicircuitos com multibombas

    Energy Technology Data Exchange (ETDEWEB)

    Veloso, Marcelo Antonio

    2003-07-01

    PANTERA-2 (from Programa para Analise Termo-hidraulica de Reatores a Agua - Program for Thermal-hydraulic Analysis of Water Reactors, Version 2), whose fundamentals are described in this work, is intended to carry out rod bundle subchannel analysis in conjunction with multiloop simulation. It solves simultaneously the conservation equations of mass, axial and lateral momentum, and energy for subchannel geometry coupled with the balance equations that describe the fluid flows in any number of coolant loops connected to a pressure vessel containing the rod bundle. As far as subchannel analysis is concerned, the basic computational strategy of PANTERA-2 comes from COBRA codes, but an alternative implicit solution method oriented to the pressure field has been used to solve the finite difference approximations for the balance laws. The results provided by the subchannel model comprise the fluid density, enthalpy, flow rate, and pressure fields in the subchannels. The loop model predicts the individual loop flows, total flow through the pressure vessel, and pump rotational speeds as a function of time subsequent to the failure of any number of the coolant pumps. The flow transients in the loops may initiated by partial, total or sequential loss of electric power to the operating pumps. Transient events caused by either shaft break or rotor locking may also be simulated. The changes in rotational speed of the pumps as a function of rime are determined from a torque balance. Pump dynamic head and hydraulic torque are calculated as a function of rotational speed and volumetric flow from two polar homologous curves supplied to the code in the tabular form. In order to illustrate the analytical capability of PANTERA-2, three sample problems are presented and discussed. Comparisons between calculated and measured results indicate that the program reproduces with a good accuracy experimental data for subchannel exit temperatures and critical heat fluxes in 5x5 rod bundles. It

  10. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un [Ithaca, NY; Gruner, Sol M [Ithaca, NY

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  11. Importância dos minerais na alimentação do pré-termo extremo Minerals in the nutrition of extremely low birth weight infants

    Directory of Open Access Journals (Sweden)

    Cleide E. P. Trindade

    2005-03-01

    Full Text Available OBJETIVO: Revisão crítica da literatura sobre os minerais cálcio, fósforo e microelementos na nutrição do pré-termo extremo, considerando a importância no crescimento, mineralização óssea e como componente de dietas. FONTES DOS DADOS: Utilizamos o banco de dados MEDLINE e o Cochrane Database of Systematic Reviews, de 1994 a 2004. Selecionamos artigos com enfoques originais, artigos de revisão e livros específicos. SÍNTESE DOS DADOS: As dificuldades na nutrição de prematuros extremos aumentam a freqüência de prematuros com restrição de crescimento, cujas conseqüências futuras estão para serem determinadas. Todavia, há pouca literatura sobre minerais, especialmente sobre micronutrientes na nutrição do pré-termo extremo, considerando-se o deficiente armazenamento e a importância destes em nutrição. O principal enfoque desta revisão foi sobre o cálcio e o fósforo na mineralização óssea e na suplementação em nutrição parenteral e enteral, bem como a avaliação crítica da nutrição pós-alta sobre a mineralização óssea. São abordadas as necessidades de micronutrientes, principalmente selênio e zinco, e a função antioxidante do selênio na provável prevenção de doenças do prematuro com atuação de radicais livres. CONCLUSÃO: Considerando os baixos estoques de minerais em prematuros extremos, há necessidade de mais pesquisas sobre minerais na nutrição destes prematuros para definir suas reais necessidades, os aspectos metabólicos, bem como aplicar os conhecimentos na formulação de dietas que permitam prevenir quadros de deficiência e conseqüências a longo prazo. Ainda há controvérsias sobre a influência de fórmulas pós-alta sobre a evolução da doença óssea da prematuridade.OBJECTIVE: To review the literature on the role of calcium, phosphorus and trace elements in the nutrition of extremely low birth weight infants, considering their importance for metabolism, bone mineralization

  12. Estratégias de posicionamento e contenção de recém-nascido pré-termo utilizadas em Unidades de Terapia Intensiva Neonatal

    Directory of Open Access Journals (Sweden)

    Thais Melo De Albuquerque

    2017-02-01

    Full Text Available Introdução: A Unidade de Terapia Intensiva Neonatal é um ambiente que proporciona técnicas e procedimentos aprimorados, um local repleto de equipamentos ricos em tecnologia e característica ímpar na assistência ao recém-nascido de risco. Com a evolução da neonatologia e a inserção dos cuidados humanizados dentro desse serviço nos últimos anos, observa-se uma mudança no prognóstico dos pré-termos. Objetivo: Pesquisar quais estratégias de posicionamento e contenção ao recém-nascido pré-termo estão sendo mais utilizados em hospitais públicos da Região Metropolitana do Recife. Métodos: Estudo descritivo e observacional. Foi realizado um questionário semiestruturado com 34 profissionais de saúde do serviço envolvidos na assistência ao recém-nascido pré-termo na Unidade de Terapia Intensiva Neonatal. Resultados: Dentre os participantes (91,17%, responderam nunca ter utilizado a “redinha” como um recurso de posicionamento. As estratégias mais utilizadas são o rolinho (100,0% e o swaddle (88,23%, porém um percentual relevante de participantes (44,11% assinalou acreditar no ganho oferecido pela “redinha”, embora esta técnica não seja utilizada nos serviços ao qual fazem parte. Conclusão: As estratégias mais utilizadas nos serviços pesquisados foram o rolinho e o swaddle, a maioria dos profissionais não tinham conhecimento prático de outros recursos. Sendo assim, este estudo considera que a prática destas medidas acarretam ganhos não só no campo de desenvolvimento, mas também simplificam o tratamento e viabilizam a recuperação do recém-nascido pré-termo.

  13. Fototerapia simples versus dupla no tratamento de recém-nascidos a termo com hiperbilirrubinemia não-hemolítica Single vs. double phototherapy in the treatment of full-term newborns with nonhemolytic hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Ignacia Silva

    2009-10-01

    Full Text Available OBJETIVO: Comparar a eficácia da fototerapia simples (1 painel versus dupla (2 painéis na redução da hiperbilirrubinemia não-hemolítica em recém-nascidos a termo. MÉTODOS: Os recém-nascidos a termo foram randomizados prospectivamente para receber fototerapia simples ou dupla. Os níveis de bilirrubina foram medidos no momento da internação e em intervalos de 12 horas, assim como em seguimento 48 horas após a alta. RESULTADOS: Trinta e sete pacientes receberam fototerapia simples, e 40, dupla. A redução média dos níveis de bilirrubina nas primeiras 24 horas de tratamento foi maior no grupo que recebeu fototerapia dupla (5,1±2,2 mg/dL versus 4,3±2,1 mg/dL, porém sem significância estatística (p = 0,18. As taxas de readmissão foram similares e nenhum dos grupos apresentou efeitos adversos. CONCLUSÃO: A fototerapia dupla não foi mais eficaz do que a fototerapia simples no tratamento da hiperbilirrubinemia não-hemolítica em recém-nascidos a termo. Entretanto, nossos resultados sugerem que a fototerapia dupla possa ser mais eficaz em recém-nascidos a termo com níveis de bilirrubina mais altos no momento da internação.OBJECTIVES: To compare the effectiveness of single (1 panel vs. double (2 panels phototherapy in reducing nonhemolytic hyperbilirubinemia in term newborns. METHODS: Term newborns with hyperbilirubinemia were prospectively randomized to receive double or single phototherapy. Bilirubin levels were measured at admission and at 12-hour intervals, as well as at a follow-up 48 hours after discharge. RESULTS: Thirty-seven patients received single and 40 double phototherapy. The mean decrease in bilirubin level in the first 24 hours of treatment was greater in the double phototherapy group (5.1±2.2 mg/dL vs. 4.3±2.1 mg/dL, but without statistical significance (p = 0.18. Readmission rates were similar and no adverse effects were found in either group. CONCLUSIONS: Double-surface was not more effective than single

  14. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  15. Crystallization In Multicomponent Glasses

    International Nuclear Information System (INIS)

    Kruger, A.A.; Hrma, P.R.

    2009-01-01

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  16. Termo de consentimento livre e esclarecido na prática reumatológica Informed consent in rheumatology care practice

    Directory of Open Access Journals (Sweden)

    José Marques Filho

    2011-04-01

    Full Text Available O termo de consentimento livre e esclarecido (tcle é um documento obrigatório nos protocolos de pesquisas com seres humanos. as normas que preconizam sua utilização são recentes na história da medicina, e o primeiro documento oficial que instituiu a necessidade do consentimento informado do sujeito de pesquisa foi o código de nuremberg (1947. Todas as normas posteriores referendaram a obrigatoriedade do consentimento informado em pesquisas. Entretanto, o consentimento informado, que representa a autonomia ou a autodeterminação dos pacientes nas relações com os médicos, demorou mais alguns anos para ter sua implantação na prática assistencial e nos códigos de deontologia médica. o que se discute hoje é a conveniência da implantação do tcle na prática médica como um todo e, em particular, na prática reumatológica. Nossa visão é que a obrigatoriedade do consentimento assinado formalmente pelo pacientes para todo procedimento médico não é razoável nem prática, podendo ele, evidentemente, ser utilizado para procedimentos mais invasivos ou terapêuticos com maiores riscos. Nossa posição é que o tcle não é uma garantia de que o paciente foi adequadamente esclarecido, condição obrigatória na prática reumatológica atual. Sua adoção na rotina assistencial tornaria a ação médica uma atividade burocrática, bem diferente da visão hipocrática, que vê a atenção médica como uma relação de confiança, em que a relação médico-paciente é o pilar fundamental para a adequada prática médica.Informed consent is a mandatory document in human subject research protocols. Its principles have been recently established in the history of Medicine, and the first official document to establish the need for an informed consent from the research subject was the Nuremberg Code (1947. All following documents confirmed that the informed consent is mandatory in human subject research. However, the informed consent, which

  17. Photonic crystal pioneer

    Science.gov (United States)

    Anscombe, Nadya

    2011-08-01

    Over the past ten years, Crystal Fiber, now part of NKT Photonics, has been busy commercializing photonic crystal fibre. Nadya Anscombe finds out about the evolution of the technology and its applications.

  18. Crystallization Pathways in Biomineralization

    Science.gov (United States)

    Weiner, Steve; Addadi, Lia

    2011-08-01

    A crystallization pathway describes the movement of ions from their source to the final product. Cells are intimately involved in biological crystallization pathways. In many pathways the cells utilize a unique strategy: They temporarily concentrate ions in intracellular membrane-bound vesicles in the form of a highly disordered solid phase. This phase is then transported to the final mineralization site, where it is destabilized and crystallizes. We present four case studies, each of which demonstrates specific aspects of biological crystallization pathways: seawater uptake by foraminifera, calcite spicule formation by sea urchin larvae, goethite formation in the teeth of limpets, and guanine crystal formation in fish skin and spider cuticles. Three representative crystallization pathways are described, and aspects of the different stages of crystallization are discussed. An in-depth understanding of these complex processes can lead to new ideas for synthetic crystallization processes of interest to materials science.

  19. Photonic Crystal Nanocavity Arrays

    National Research Council Canada - National Science Library

    Altug, Hatice; Vuckovic, Jelena

    2006-01-01

    We recently proposed two-dimensional coupled photonic crystal nanocavity arrays as a route to achieve a slow-group velocity of light in all crystal directions, thereby enabling numerous applications...

  20. Growth of dopamine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu [D. G. Ruparel College, Senapati Bapat Marg, Mahim, Mumbai – 400 016 (India)

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  1. Apparatus for mounting crystal

    Science.gov (United States)

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  2. ALICE photon spectrometer crystals

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Members of the mechanical assembly team insert the last few crystals into the first module of ALICE's photon spectrometer. These crystals are made from lead-tungstate, a crystal as clear as glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, emitting a flash of light allowing the energy of photons, electrons and positrons to be measured.

  3. Crystal Growth Technology

    Science.gov (United States)

    Scheel, Hans J.; Fukuda, Tsuguo

    2004-06-01

    This volume deals with the technologies of crystal fabrication, of crystal machining, and of epilayer production and is the first book on industrial and scientific aspects of crystal and layer production. The major industrial crystals are treated: Si, GaAs, GaP, InP, CdTe, sapphire, oxide and halide scintillator crystals, crystals for optical, piezoelectric and microwave applications and more. Contains 29 contributions from leading crystal technologists covering the following topics: General aspects of crystal growth technology Silicon Compound semiconductors Oxides and halides Crystal machining Epitaxy and layer deposition Scientific and technological problems of production and machining of industrial crystals are discussed by top experts, most of them from the major growth industries and crystal growth centers. In addition, it will be useful for the users of crystals, for teachers and graduate students in materials sciences, in electronic and other functional materials, chemical and metallurgical engineering, micro-and optoelectronics including nanotechnology, mechanical engineering and precision-machining, microtechnology, and in solid-state sciences.

  4. Food crystallization and eggs.

    Science.gov (United States)

    Egg products can be utilized to control crystallization in a diverse realm of food products. Albumen and egg yolk can aid in the control of sugar crystal formation in candies. Egg yolk can enhance the textural properties and aid in the control of large ice crystal formation in frozen desserts. In...

  5. Método de prevenção de lesão nasal causada por CPAP em recém-nascido pré-termo: relato de caso

    Directory of Open Access Journals (Sweden)

    Cristiane Raupp Nunes

    2013-02-01

    Full Text Available A administração de pressão positiva contínua nas vias aéreas através do CPAP nasal tem sido utilizada no tratamento das doenças respiratórias neonatais como meio de prover suporte ventilatório nos RN pré-termo, produzindo adequada troca gasosa, decréscimo das complicações induzidas pela ventilação mecânica invasiva e redução da displasia broncopulmonar. A pronga nasal é o dispositivo de conexão às vias aéreas mais utilizado para este fim, estando disponível em diferentes tamanhos e constituída de material leve e flexível. Apesar das vantagens, esse dispositivo pode lesionar as narinas causando desconforto e desfiguramento nasal. Relatamos o caso de um pré-termo de extremo baixo peso que fez uso de CPAP nasal com um sistema desenvolvido pelas enfermeiras da Unidade de Tratamento Intensivo Neonatal do HCPA para proteção da pele, mucosa e septo nasal, sendo este objetivo satisfatoriamente atingido.

  6. Protein Crystal Growth

    Science.gov (United States)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  7. Photonic crystal light source

    Science.gov (United States)

    Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  8. Respostas fisiológicas da Posição Mãe-Canguru em bebês pré-termos, de baixo peso e ventilando espontaneamente

    Directory of Open Access Journals (Sweden)

    Miltersteiner Aline R

    2003-01-01

    Full Text Available OBJETIVO: avaliar as respostas fisiológicas - freqüência cardíaca, saturação periférica de oxigênio, temperatura axilar e freqüência respiratória - em bebês pré-termos estáveis e em ventilação espontânea, submetidos à observação na incubadora e à Posição Mãe-Canguru. MÉTODOS: foram estudados 23 pré-termos estáveis hemodinamicamente, em ventilação espontânea, sem doença pulmonar diagnosticada, provenientes do Centro de Neonatologia do Hospital Conceição, Porto Alegre. Os pacientes foram distribuídos em Grupo I (incubadora e Grupo II (Posição Mãe-Canguru para um estudo de intervenção, de amostras pareadas, sendo cada paciente controle de si mesmo. Os dados foram registrados no primeiro minuto (T01, aos 30 (T30 e aos 60 minutos (T60. Utilizou-se o teste t de Student para comparação entre os grupos. RESULTADOS: os pacientes apresentaram uma média de idade gestacional de 34 semanas, média de peso pós-natal de 1780 g e mediana de 264 horas de vida. Observou-se um aumento estatisticamente significante na freqüência cardíaca em T30, na saturação de oxigênio em T30 e T60 e na temperatura axilar em T60, comparando o grupo da Posição Mãe-Canguru ao grupo controle. CONCLUSÕES: a Posição Mãe-Canguru promoveu aumento nos valores das respostas fisiológicas estudadas em pré-termos, quando instituída por uma hora, em comparação ao mesmo período na incubadora, sendo possível sua utilização durante atendimento fisioterapêutico.

  9. Scintillation crystal mounting apparatus

    International Nuclear Information System (INIS)

    Engdahl, L.W.; Deans, A.J.

    1982-01-01

    An improved detector head for a gamma camera is disclosed. The detector head includes a housing and a detector assembly mounted within the housing. Components of the detector assembly include a crystal sub-assembly, a phototube array, and a light pipe between the phototube array and crystal sub-assembly. The invention provides a unique structure for maintaining the phototubes in optical relationship with the light pipe and preventing the application of forces that would cause the camera's crystal to crack

  10. CMS lead tungstate crystals

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    These crystals are made from lead tungstate, a crystal that is as clear as glass yet with nearly four times the density. They have been produced in Russia to be used as scintillators in the electromagnetic calorimeter on the CMS experiment, part of the LHC project at CERN. When an electron, positron or photon passes through the calorimeter it will cause a cascade of particles that will then be absorbed by these scintillating crystals, allowing the particle's energy to be measured.

  11. Macromolecular crystallization in microgravity

    International Nuclear Information System (INIS)

    Snell, Edward H; Helliwell, John R

    2005-01-01

    Density difference fluid flows and sedimentation of growing crystals are greatly reduced when crystallization takes place in a reduced gravity environment. In the case of macromolecular crystallography a crystal of a biological macromolecule is used for diffraction experiments (x-ray or neutron) so as to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal then the greater the molecular structure detail that can be extracted. It is this structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences, with major potential in understanding disease pathologies. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyse the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural advances. Finally, limitations and alternatives to microgravity and future directions for this research are covered. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry and mathematics meet to enable insight to the fundamentals of life. As the reader will see, there is a great deal of physics involved when the microgravity environment is applied to crystallization, some of it known, and undoubtedly much yet to

  12. Active Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Ek, Sara

    This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... due to photonic crystal dispersion. The observations are explained by the enhancement of net gain by light slow down. Another application based on active photonic crystal waveguides is micro lasers. Measurements on quantum dot micro laser cavities with different mirror configurations and photonic...

  13. A crystal barrel

    CERN Multimedia

    2007-01-01

    The production of crystals for the barrel of the CMS electromagnetic calorimeter has been completed. This is an important milestone for the experiment, which received the last of its 62,960 crystals on 9 March. The members of the team responsible for the crystal acceptance testing at CERN display the last crystal for the CMS electromagnetic calorimeter barrel. From left to right: Igor Tarasov, Etiennette Auffray and Hervé Cornet.One of the six machines specially developed to measure 67 different parameters on each crystal. Igor Tarasov is seen inserting the last batch of crystals into the machine. The last of the 62,960 CMS barrel crystals arrived at CERN on 9 March. Once removed from its polystyrene protection, this delicate crystal, like thousands of its predecessors, will be inserted into the last of the 36 supermodules of the barrel electromagnetic calorimeter in a few days' time. This marks the end of an important chapter in an almost 15-year-long journey by the CMS crystals team, some of whose member...

  14. Automation in biological crystallization.

    Science.gov (United States)

    Stewart, Patrick Shaw; Mueller-Dieckmann, Jochen

    2014-06-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given.

  15. Crystallization Formulation Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

  16. Estrutura a termo da taxa de juros e imunização: novas perspectivas na gestão do risco de taxa de juros em fundo de pensão

    OpenAIRE

    Machado,Sérgio Jurandyr; Motta,Luis Felipe Jacques da

    2007-01-01

    O termo imunização denota a construção de uma carteira de títulos de forma a torná-la imune a variações nas taxas de juros. No caso dos fundos de pensão, o objetivo da imunização é distribuir os recebimentos intermediários e finais dos ativos de acordo com a previsão para o fluxo de pagamentos dos benefícios. Nesse sentido, o artigo busca comparar o desempenho de duas alternativas de imunização ao método tradicional que restringe o gerenciamento do risco de taxa de juros à compatibilização da...

  17. Construção da permanência do objeto em crianças nascidas pré-termo muito baixo peso Object permanence construction in very low birth weight preterm infants

    Directory of Open Access Journals (Sweden)

    Karina Elena Bernardis Bühler

    2007-09-01

    Full Text Available OBETIVO: descrever e comparar o processo de construção da permanência do objeto entre crianças com histórico de prematuridade e muito baixo peso e crianças nascidas a termo com desenvolvimento típico. MÉTODOS: participaram deste estudo 22 crianças, sendo 8 crianças nascidas pré-termo e muito baixo peso (grupo pesquisa - GP e 14 crianças nascidas a termo (grupo controle - GC. Os sujeitos foram submetidos a avaliações mensais de cognição e linguagem, contendo a avaliação da noção de permanência do objeto. Todas as sessões foram registradas em vídeo e transcritas em protocolo específico. As crianças de ambos os grupos foram avaliadas dos 6 aos 12 meses, sendo considerada para o GP, a idade corrigida. Os dados foram analisados de forma quantitativa e qualitativa. RESULTADOS: observou-se diferença estatisticamente significante entre os dois grupos para todas as fases da construção da permanência do objeto, evidenciando o atraso (uma média de 2 a 3 meses de atraso no desenvolvimento cognitivo, apresentado pelo GP, em relação ao GC, durante o período sensório-motor. CONCLUSÃO: os resultados reforçam a idéia de que as crianças nascidas pré-termo e muito baixo peso apresentam risco para alterações ou atrasos no desenvolvimento cognitivo e de linguagem, justificando a elaboração de programas de intervenção fonoaudiológica junto a essas crianças, já durante o primeiro ano de vida.PURPOSE: to describe and compare the process of object permanence construction in very low birth weight preterm and full-term typical developing infants. METHODS: eight very low birth weight infants (experimental group - EG and 14 full-term infants (control group - CG were monthly evaluated as for language and cognition abilities, including the assessment of the object permanence notion. All sessions were recorded in video and transcribed in specific protocols. Children of both groups were evaluated from 6 to 12 months of age

  18. Acompanhamento da icterícia neonatal em recém-nascidos de termo e prematuros tardios Follow-up of neonatal jaundice in term and late premature newborns

    Directory of Open Access Journals (Sweden)

    Fernando Perazzini Facchini

    2007-08-01

    Full Text Available OBJETIVO: Relatar os resultados de um projeto de acompanhamento de recém-nascidos de termo e próximos ao termo ictéricos no período neonatal. MÉTODOS: Foram encaminhados a ambulatório especializado neonatos com peso > 2.000 g e/ou idade gestacional > 35 semanas, cuja icterícia na alta foi avaliada inicialmente com o icterômetro de Ingram, Bilicheck® e, se indicado, com bilirrubinômetro Unistat (Leica. A bilirrubinemia destes recém-nascidos situava-se no ou acima do percentil 40 do nomograma elaborado por Bhutani. Todos recém-nascidos tratados com fototerapia durante internação foram reavaliados laboratorialmente 24 horas após suspensão do tratamento. A indicação de reinternação para tratamento fototerápico intensivo foi para paciente com nível > 20 mg/dL. RESULTADOS: De um total de 11.259 neonatos, 2.452 (21,8% foram encaminhados para acompanhamento, dos quais 87,2% (2.140 retornaram. Oitenta neonatos retornados foram reinternados. Dos 2.452 encaminhados para retorno, 180 (7,3% tinham bilirrubinemia > 15 mg/dL na alta. Destes, 151 retornaram para acompanhamento. Vinte (13,2% foram reinternados para tratamento. Do total de reinternados, dois recém-nascidos apresentaram nível > 25 mg/dL e nenhum > 30 mg/dL. Todos responderam rapidamente à fototerapia intensiva, e não houve necessidade de utilizar exsangüinotransfusões. CONCLUSÕES: Nossos resultados sugerem que o esquema adotado é eficiente na detecção e prevenção de hiperbilirrubinemias de risco para produzir encefalopatia bilirrubínica em recém-nascidos de termo e próximos ao termo.OBJECTIVE: To report on the results of a project following term and near term newborn infants who were jaundiced during the neonatal period. METHODS: Neonates were referred to the follow-up clinic with weight > 2,000 g and/or gestational age > 35 weeks, and jaundice at discharge was initially assessed with an Ingram icterometer or Bilicheck and, if indicated, with a Unistat

  19. Respostas fisiológicas e comportamentais de recém-nascidos pré-termos submetidos a duas técnicas de banho de imersão: ensaio clínico cruzado

    OpenAIRE

    Patricia de Freitas

    2015-01-01

    Introdução: a revisão de literatura aponta que os recém-nascidos submetidos ao banho de imersão produzem menor variação térmica pós-banho comparado aos submetidos ao banho com esponja. No Brasil, o Ministério da Saúde vem capacitando profissionais que atuam em unidades de internação neonatal para implementar o Método Mãe Canguru e, entre outras práticas, recomenda que o recém-nascido pré-termo (RNPT) e com baixo peso seja submetido ao banho de imersão envolto em cueiro ou lençol, sugerindo mu...

  20. Serious game e-Baby-Família: tecnologia educacional digital direcionada a oxigenação de bebês pré-termo desenvolvida junto ao pais

    OpenAIRE

    Marcela Mobiglia D\\'Agostini

    2015-01-01

    Mundialmente, estima-se que nasçam, por ano, 15 milhões de bebês pré-termo com alto risco de morbi-mortalidade neonatal, pós-neonatal e durante a infância, devido à imaturidade dos órgãos/sistemas, principalmente respiratório. Tanto que, re-hospitalizações, por afecções respiratórias, são comuns nesta população. Objetivou-se desenvolver uma tecnologia educacional digital, serious game, em e-learning e m-learning, que possua subsídios para suprir as necessidades de aprendizagem dos pais...

  1. Influência da estimulação sensório-motora-oral em recém-nascidos pré-termo Influence of sensory-motor-oral stimulation on preterm newborns

    Directory of Open Access Journals (Sweden)

    Patricia Pereira Costa

    2011-08-01

    Full Text Available OBJETIVO: verificar a influência da estimulação sensório-motora-oral em recém-nascidos pré-termo. MÉTODOS: a amostra constou de 28 recém-nascidos pré-termo internados na Unidade de Terapia Intensiva Neonatal de um Hospital Universitário. Os sujeitos foram alocados em dois grupos, o estimulado e o controle. O grupo estimulado recebeu estimulação sensório-motora-oral duas vezes por dia. Realizaram-se duas avaliações, mensurando frequência respiratória e cardíaca, taxa de transferência, tempo de transição entre sonda e via oral plena, bem como incremento de peso. Os resultados foram analisados por meio do software STATA (10, comparando-se os grupos com o Teste T Student independente (pPURPOSE: to evaluate the influence of a sensory-motor-oral stimulation in preterm newborns. METHODS: twenty-eight preterm newborns in a neonatal intensive care unit of a University Hospital were randomly placed into stimulated and control groups. The stimulated group received a sensory-motor-oral stimulation twice a day. There were two ratings, measuring respiratory rate and heart rate, transfer tax, transition time between tube and oral feeding and weight increase. The results were analyzed through STATA 10 software, and the groups were compared through the Independent T Student Test (p<0,05. RESULTS: no statistically significant difference was found between the groups. CONCLUSION: there was no influence of sensory-motor-oral stimulation on the evaluated parameters.

  2. Intraempreendedorismo: Um Estudo de Caso sobre o Entendimento e a Aplicação do Termo em uma Instituição Bancária [doi: 10.5329/RECADM.20080702006

    Directory of Open Access Journals (Sweden)

    Nelson Chieh

    2008-11-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 RESUMO O objetivo deste artigo é analisar o entendimento dos funcionários de um grande banco brasileiro sobre o tema intraempreendedorismo, bem como sua aplicabilidade à empresa. Para tanto, foram efetuadas 19 entrevistas com gestores, executivos e funcionários da organização estudada. Como resultado, verificou-se que o termo intraempreendedorismo ainda é pouco conhecido na empresa, muito embora os conceitos e fundamentos ligados ao termo sejam compreendidos. A existência de diversos programas institucionais relacionados ao intraempreen-dedorismo é um forte indício de que a empresa busca valorizar e atrair cada vez mais funcionários com perfil intraempreendedor. Contudo, o entendimento sobre essas iniciativas organizacionais não é homogêneo entre as áreas. Verificou-se também que o incentivo e reconhecimento ao profissional intraempreendedor ainda é muito dependente de ações individuais dos gestores diretos.   Palavras-Chave Intraempreendedorismo, intraempreendedor, empreendedorismo corporativo, inovação.     ABSTRACT This paper aims at analyzing the understanding of company staff observed concerning matters associated to the theme intrapreneurship, as well as its application within the company. In this study, the existence of corporate practices will also be verified that aim towards the encouragement of intrapreneurship. Using interview techniques, it is intended to verify the level of staff knowledge about the concepts associated to intrapreneurship. The human resource corporate programs and the cultural change will be analyzed through the light of the characteristics of an intrapreneurial organization with the purpose of identifying the existence or not of institutional incentive.   Keywords Intrapreneurship, intrapreneur, corporate entrepreneurship, innovation.

  3. Uma Análise das Diferenças em Termos da Cultura a Partir do Projeto de Substituição da IAS 39: Financial Instruments – Recognition and Measurement

    Directory of Open Access Journals (Sweden)

    Cláudia Daniela Ferreira da Mota Carvalho

    2015-01-01

    Full Text Available A cultura contabilística de cada país é frequentemente encaradacomo um obstáculo à plena harmonização contabilística.Este trabalho propõe-se a analisar as diferenças em termos dacultura a partir da participação dos respondentes nos processosde emissão/alteração de normas do International AccountingStandard Board (Iasb. Para o efeito, foram analisadas as commentletters enviadas ao Iasb no contexto da primeira parte da primeirafase do projeto de substituição da International AccountingStandard (IAS 39: Financial Instruments – Recognition andMeasurement pela International Financial Reporting Standard(IFRS 9. Os países respondentes foram identificados em funçãoda classificação proposta por Gray (1988, sendo posteriormenteos dados recolhidos submetidos ao teste não paramétrico do quiquadrado.Os resultados deste estudo evidenciam a existênciade diferenças em termos da cultura nas respostas obtidas dospaíses, particularmente no contexto do valor contabilísticodo conservadorismo, não se identificando evidências de taisdiferenças para os valores do secretismo, do profissionalismo eda uniformidade. Conclui-se, assim, que os países classificadoscomo conservadores têm preferência por práticas de mensuraçãomais conservadoras, baseadas, designadamente, no custo ou nocusto amortizado, em detrimento de critérios de mensuraçãobaseados no justo valor. Pretende-se que os resultados obtidosneste estudo prestem o suporte necessário à tomada de decisõespor parte dos organismos emissores de normas internacionais,bem como pelos responsáveis nacionais pela subscrição dasreferidas normas.

  4. Thermotropic Ionic Liquid Crystals

    Science.gov (United States)

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. PMID:28879986

  5. Thermotropic Ionic Liquid Crystals.

    Science.gov (United States)

    Axenov, Kirill V; Laschat, Sabine

    2011-01-14

    The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  6. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  7. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  8. Tactical Miniature Crystal Oscillator.

    Science.gov (United States)

    1980-08-01

    manufactured by this process are expected to require 30 days to achieve minimum aging rates. (4) FUNDEMENTAL CRYSTAL RETRACE MEASUREMENT. An important crystal...considerable measurement time to detect differences and characterize components. Before investing considerable time in a candidate reactive element, a

  9. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

  10. Optically Anomalous Crystals

    CERN Document Server

    Shtukenberg, Alexander; Kahr, Bart

    2007-01-01

    Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...

  11. Progress on photonic crystals

    CERN Document Server

    Lecoq, P; Gundacker, S; Hillemanns, H; Jarron, P; Knapitsch, A; Leclercq, J L; Letartre, X; Meyer, T; Pauwels, K; Powolny, F; Seassal, C

    2010-01-01

    The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well ...

  12. Organic semiconductor crystals.

    Science.gov (United States)

    Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

    2018-01-22

    Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

  13. Intraempreendedorismo: Um Estudo de Caso sobre o Entendimento e a Aplicação do Termo em uma Instituição Bancária

    Directory of Open Access Journals (Sweden)

    Nelson Chieh

    2008-11-01

    ; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} -->

    RESUMO

    O objetivo deste artigo é analisar o entendimento dos funcionários de um grande banco brasileiro sobre o tema intraempreendedorismo, bem como sua aplicabilidade à empresa. Para tanto, foram efetuadas 19 entrevistas com gestores, executivos e funcionários da organização estudada. Como resultado, verificou-se que o termo intraempreendedorismo ainda é pouco conhecido na empresa, muito embora os conceitos e fundamentos ligados ao termo sejam compreendidos. A existência de diversos programas institucionais relacionados ao intraempreen-dedorismo é um forte indício de que a empresa busca valorizar e atrair cada vez mais funcionários com perfil intraempreendedor. Contudo, o entendimento sobre essas iniciativas organizacionais não é homogêneo entre as áreas. Verificou-se também que o incentivo e reconhecimento ao profissional intraempreendedor ainda é muito dependente de a

  14. Disorder in Protein Crystals.

    Science.gov (United States)

    Clarage, James Braun, II

    1990-01-01

    Methods have been developed for analyzing the diffuse x-ray scattering in the halos about a crystal's Bragg reflections as a means of determining correlations in atomic displacements in protein crystals. The diffuse intensity distribution for rhombohedral insulin, tetragonal lysozyme, and triclinic lysozyme crystals was best simulated in terms of exponential displacement correlation functions. About 90% of the disorder can be accounted for by internal movements correlated with a decay distance of about 6A; the remaining 10% corresponds to intermolecular movements that decay in a distance the order of size of the protein molecule. The results demonstrate that protein crystals fit into neither the Einstein nor the Debye paradigms for thermally fluctuating crystalline solids. Unlike the Einstein model, there are correlations in the atomic displacements, but these correlations decay more steeply with distance than predicted by the Debye-Waller model for an elastic solid. The observed displacement correlations are liquid -like in the sense that they decay exponentially with the distance between atoms, just as positional correlations in a liquid. This liquid-like disorder is similar to the disorder observed in 2-D crystals of polystyrene latex spheres, and similar systems where repulsive interactions dominate; hence, these colloidal crystals appear to provide a better analogy for the dynamics of protein crystals than perfectly elastic lattices.

  15. Estudo retrospectivo de crianças pré-termo no Ambulatório de Especialidades Jardim Peri-Peri Retrospective study of preterm newborn infants at the ambulatory of specialities Jardim Peri-Peri

    Directory of Open Access Journals (Sweden)

    Silvia Helena Tavares Lorena

    2009-06-01

    Full Text Available OBJETIVO: Determinar a prevalência da retinopatia da prematuridade em recém-nascidos pré-termo, associando-a com seus fatores de risco, além de comparar a incidência do vício refracional do tipo miopia e estrabismo entre as crianças pré-termo que desenvolveram a retinopatia da prematuridade (Grupo I e as que não manifestaram esta retinopatia (Grupo II. MÉTODOS: Neste trabalho, empregou-se um estudo do tipo transversal, retrospectivo e documental dos prontuários de 147 crianças pré-termo, as quais foram atendidas no Ambulatório de Especialidades Jardim Peri-Peri, oriundas da Maternidade Mário Degni, nascidas no período de 7 de julho de 2004 a 10 de julho de 2008. O mapeamento de retina, com depressão escleral foi realizado, inicialmente entre 3 e 8 semanas de vida pós-natal e repetido a cada 1 a 4 semanas, dependendo dos achados fundoscópicos, até que a vascularização da retina se completasse ou a retinopatia da prematuridade se estabelecesse, e seguidos em consulta oftalmológica anual constituída por mapeamento de retina e exame refracional. Para a classificação da retinopatia da prematuridade foram utilizados os critérios da "International Classification of Retinopathy of Prematurity". Procedeu-se à análise do grupo total de prematuros, classificando-os em grupo I e grupo II, analisando a incidência de miopia e astigmatismo em cada grupo estudado. RESULTADOS: Nesta casuística, verificou-se a retinopatia da prematuridade em 35 crianças pré-termo (23%, sendo que 112 crianças pré-termo (77% não desenvolveram esta retinopatia. No grupo I, 34 crianças (97% apresentaram-se no estágio 1 da retinopatia da prematuridade com regressão espontânea, e 1 criança (3% apresentou-se no estágio 2, evoluindo para doença limiar, tendo sido submetida ao tratamento cirúrgico por fotocoagulação a laser. Todos os recém-nascidos que manifestaram a retinopatia da prematuridade fizeram uso de oxigenoterapia, sendo a ventila

  16. Crystals in light.

    Science.gov (United States)

    Kahr, Bart; Freudenthal, John; Gunn, Erica

    2010-05-18

    We have made images of crystals illuminated with polarized light for almost two decades. Early on, we abandoned photosensitive chemicals in favor of digital electrophotometry with all of the attendant advantages of quantitative intensity data. Accurate intensities are a boon because they can be used to analytically discriminate small effects in the presence of larger ones. The change in the form of our data followed camera technology that transformed picture taking the world over. Ironically, exposures in early photographs were presumed to correlate simply with light intensity, raising the hope that photography would replace sensorial interpretation with mechanical objectivity and supplant the art of visual photometry. This was only true in part. Quantitative imaging accurate enough to render the separation of crystalloptical quantities had to await the invention of the solid-state camera. Many pioneers in crystal optics were also major figures in the early history of photography. We draw out the union of optical crystallography and photography because the tree that connects the inventors of photography is a structure unmatched for organizing our work during the past 20 years, not to mention that silver halide crystallites used in chemical photography are among the most consequential "crystals in light", underscoring our title. We emphasize crystals that have acquired optical properties such as linear birefringence, linear dichroism, circular birefringence, and circular dichroism, during growth from solution. Other crystalloptical effects were discovered that are unique to curiously dissymmetric crystals containing embedded oscillators. In the aggregate, dyed crystals constitute a generalization of single crystal matrix isolation. Simple crystals provided kinetic stability to include guests such as proteins or molecules in excited states. Molecular lifetimes were extended for the preparation of laser gain media and for the study of the photodynamics of single

  17. Magnetic ions in crystals

    CERN Document Server

    Stevens, K W

    2014-01-01

    There have been many demonstrations, particularly for magnetic impurity ions in crystals, that spin-Hamiltonians are able to account for a wide range of experimental results in terms of much smaller numbers of parameters. Yet they were originally derived from crystal field theory, which contains a logical flaw; electrons on the magnetic ions are distinguished from those on the ligands. Thus there is a challenge: to replace crystal field theory with one of equal or greater predictive power that is based on a surer footing. The theory developed in this book begins with a generic Hamiltonian, on

  18. Silumins alloy crystallization

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2009-07-01

    Full Text Available This paper presents the results of research, by ATD method, of hypo-, near- and hyperutectic silumins crystallization containing the following alloying additives: Mg, Ni, Cu, Cr, Mo, W, V. It has been shown that, depending on their concentration may crystallize pre-eutectic or eutectic multicomponent phases containing these alloy additives. It has been revealed that any subsequent crystallizable phase nucleate and grows near the liquid/former crystallized phase interface. In multiphases compound also falls the silicon, resulting in a reduction in its quantity and the fragmentation in the eutectic mixture. As a result, it gets a high hardness of silumins in terms of 110-220HB.

  19. Hypersonic phononic crystals.

    Science.gov (United States)

    Gorishnyy, T; Ullal, C K; Maldovan, M; Fytas, G; Thomas, E L

    2005-03-25

    In this Letter we propose the use of hypersonic phononic crystals to control the emission and propagation of high frequency phonons. We report the fabrication of high quality, single crystalline hypersonic crystals using interference lithography and show that direct measurement of their phononic band structure is possible with Brillouin light scattering. Numerical calculations are employed to explain the nature of the observed propagation modes. This work lays the foundation for experimental studies of hypersonic crystals and, more generally, phonon-dependent processes in nanostructures.

  20. Avaliação do desenvolvimento inicial de crianças nascidas pré-termo Evaluación del desarrollo inicial de niños nacidos prematuramente Assessment of preterm children's early development

    Directory of Open Access Journals (Sweden)

    Cibelle Kayenne Martins Roberto Formiga

    2009-06-01

    Full Text Available O nascimento prematuro é um evento que traz implicações ao desenvolvimento saudável da criança. Diversos estudos têm sido desenvolvidos sobre a avaliação de crianças nascidas pré-termo e a influência de múltiplos fatores de risco na trajetória de desenvolvimento. Este estudo realizou uma revisão sistemática da literatura de 2000 a 2005 sobre a avaliação do desenvolvimento de crianças pré-termo até 24 meses de idade. Os fatores de risco biológicos estiveram presentes em todos os estudos, destacando-se a hemorragia intraventricular, enterocolite necrotizante, doença pulmonar crônica e retardo do crescimento intra-uterino como os mais estudados. O desenvolvimento motor da criança foi a área mais investigada. Quanto à idade, as primeiras avaliações foram direcionadas aos seis primeiros meses de vida. O risco neonatal, baixo peso ao nascimento, sexo masculino do bebê, lesões cerebrais e movimentos espontâneos anormais nas primeiras semanas foram fatores preditores do desenvolvimento das crianças pré-termo aos dois anos de idade.El nacimiento prematuro es un evento que trae implicaciones en el desarrollo saludable del niño. Diversos estudios han sido efectuados sobre la evaluación de niños nacidos prematuramente y la influencia de múltiples factores de riesgo en la trayectoria de su desarrollo. Este estudio realizó una revisión sistemática de la literatura de 2.000 a 2,005 sobre la evaluación del desarrollo de niños prematuros hasta los 24 meses de edad. Los factores de riesgo biológicos estuvieron presentes en todos los estudios, destacándose la hemorragia interventricular, la enterocolitis necrosante, la enfermedad pulmonar crónica y el retardo del crecimiento intrauterino como los más estudiados. El desarrollo motor del niño fue el área más investigada. En lo que se refiere a la edad, las primeras evaluaciones fueron dirigidas a los seis primeros meses de vida. El riesgo neonatal, bajo peso al nacer

  1. Crystal Genetics, Inc.

    Science.gov (United States)

    Kermani, Bahram G

    2016-07-01

    Crystal Genetics, Inc. is an early-stage genetic test company, focused on achieving the highest possible clinical-grade accuracy and comprehensiveness for detecting germline (e.g., in hereditary cancer) and somatic (e.g., in early cancer detection) mutations. Crystal's mission is to significantly improve the health status of the population, by providing high accuracy, comprehensive, flexible and affordable genetic tests, primarily in cancer. Crystal's philosophy is that when it comes to detecting mutations that are strongly correlated with life-threatening diseases, the detection accuracy of every single mutation counts: a single false-positive error could cause severe anxiety for the patient. And, more importantly, a single false-negative error could potentially cost the patient's life. Crystal's objective is to eliminate both of these error types.

  2. Diffusion in Coulomb crystals.

    Science.gov (United States)

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  3. Bipolarons in nonmetallic crystals

    International Nuclear Information System (INIS)

    Vinetskii, V.L.; Pashitskii, E.A.; Yanchuk, V.A.

    1987-01-01

    The binding energy of a bipolaron in an ionic crystal increases substantially in the case of strong anisotropy of the effective masses of the free carriers of the easy plane type or easy axis type. In the second case the polaron is cigar-like in shape and the coaxial configuration of bipolarons is energetically favorable. In this case a significant gain in the binding energy and in the width of the region of existence of the bipolaron, with respect to the dielectric constant and the magnitude of the electron-phonon interaction constant, compared with an isotropic crystal, is obtained only for quasi-two-dimensional, or layered, and quasi-one-dimensional, or chainlike, crystals. This work shows that a significant gain in the binding energy can be obtained by taking into account the anisotropy of the dielectric constant of the crystal and localization of the electron wave functions in directions perpendicular to the layers and chains of atoms

  4. Liquid Crystal Colloids

    Science.gov (United States)

    Smalyukh, Ivan I.

    2018-03-01

    Colloids are abundant in nature, science, and technology, with examples ranging from milk to quantum dots and the colloidal atom paradigm. Similarly, liquid crystal ordering is important in contexts ranging from biological membranes to laboratory models of cosmic strings and liquid crystal displays in consumer devices. Some of the most exciting recent developments in both of these soft matter fields emerge at their interface, in the fast-growing research arena of liquid crystal colloids. Mesoscale self-assembly in such systems may lead to artificial materials and to structures with emergent physical behavior arising from patterning of molecular order and nano- or microparticles into precisely controlled configurations. Liquid crystal colloids show exceptional promise for new discovery that may impinge on composite material fabrication, low-dimensional topology, photonics, and so on. Starting from physical underpinnings, I review the state of the art in this fast-growing field, with a focus on its scientific and technological potential.

  5. Creep of crystals

    International Nuclear Information System (INIS)

    Poirier, J.-P.

    1988-01-01

    Creep mechanisms for metals, ceramics and rocks, effect of pressure and temperature on deformation processes are considered. The role of crystal defects is analysed, different models of creep are described. Deformation mechanisms maps for different materials are presented

  6. Thermotropic Ionic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Sabine Laschat

    2011-01-01

    Full Text Available The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  7. Fototerapia causa danos ao DNA de leucócitos mononucleares periféricos em recém-nascidos a termo Phototherapy causes DNA damage in peripheral mononuclear leukocytes in term infants

    Directory of Open Access Journals (Sweden)

    Ali Aycicek

    2008-04-01

    Full Text Available OBJETIVO: Determinar se a fita de DNA de leucócitos mononucleares endógenos é alvo de fototerapia. MÉTODOS: O estudo incluiu 65 recém-nascidos a termo com idades entre 3 e 10 dias que haviam sido expostos a fototerapia intensiva (n = 23 ou convencional (n = 23 por pelo menos 48 horas devido à icterícia neonatal, além de um grupo controle (n = 19. Dano ao DNA foi avaliado por eletroforese alcalina em gel de célula única (ensaio cometa. A capacidade antioxidante total plasmática e os níveis de estado oxidativo total também foram medidos, e a correlação entre danos ao DNA e estresse oxidativo foi investigada. RESULTADOS: Os valores médios de escores de danos ao DNA nos grupos de fototerapia intensiva e convencional foram significativamente maiores do que os do grupo controle (p 0,05. Não houve correlações significativas entre escores de danos ao DNA e bilirrubina, estado oxidante total e níveis de estresse oxidativo entre os grupos de fototerapia (p > 0,05. CONCLUSÕES: Tanto a fototerapia intensiva quanto a convencional causam danos ao DNA dos leucócitos mononucleares endógenos em recém-nascidos a termo com icterícia.OBJECTIVE: Our aim was to determine whether endogenous mononuclear leukocyte DNA strand is a target of phototherapy. METHODS: The study included 65 term infants aged between 3-10 days that had been exposed to intensive (n = 23 or conventional (n = 23 phototherapy for at least 48 hours due to neonatal jaundice, and a control group (n = 19. DNA damage was assayed by single-cell alkaline gel electrophoresis (comet assay. Plasma total antioxidant capacity and total oxidant status levels were also measured, and correlation between DNA damage and oxidative stress was investigated. RESULTS: Mean values of DNA damage scores in both the intensive and conventional phototherapy groups were significantly higher than those in the control group (p 0.05. There were no significant correlations between DNA damage scores and

  8. Uma análise das diferenças em termos da cultura a partir do projeto de substituição da IAS 39: financial instruments - recognition and measurement

    Directory of Open Access Journals (Sweden)

    Cláudia Daniela Ferreira da Mota Carvalho

    2015-03-01

    Full Text Available A cultura contabilística de cada país é frequentemente encarada como um obstáculo à plena harmonização contabilística. Este trabalho propõe-se a analisar as diferenças em termos da cultura a partir da participação dos respondentes nos processos de emissão/alteração de normas do International Accounting Standard Board (Iasb. Para o efeito, foram analisadas as comment letters enviadas ao Iasb no contexto da primeira parte da primeira fase do projeto de substituição da International Accounting Standard (IAS 39: Financial Instruments - Recognition and Measurement pela International Financial Reporting Standard (IFRS 9. Os países respondentes foram identificados em função da classificação proposta por Gray (1988, sendo posteriormente os dados recolhidos submetidos ao teste não paramétrico do qui-quadrado. Os resultados deste estudo evidenciam a existência de diferenças em termos da cultura nas respostas obtidas dos países, particularmente no contexto do valor contabilístico do conservadorismo, não se identificando evidências de tais diferenças para os valores do secretismo, do profissionalismo e da uniformidade. Conclui-se, assim, que os países classificados como conservadores têm preferência por práticas de mensuração mais conservadoras, baseadas, designadamente, no custo ou no custo amortizado, em detrimento de critérios de mensuração baseados no justo valor. Pretende-se que os resultados obtidos neste estudo prestem o suporte necessário à tomada de decisões por parte dos organismos emissores de normas internacionais, bem como pelos responsáveis nacionais pela subscrição das referidas normas.

  9. Estudo vídeo-polissonográfico em recém-nascidos de termo pequenos para a idade gestacional Video-polygraphic-EEG study in the full-term newborn with low birthweight for their gestational age

    Directory of Open Access Journals (Sweden)

    NIURA A.M R. PADULA

    1999-09-01

    Full Text Available Analisamos o exame video-polissonográfico de 26 recém-nascidos de termo (RNT com 24 horas de vida. Os RN tinham exame neurológico e ultrassonográfico cerebral normais e apresentaram período perinatal isento de complicações. Foram subdivididos em dois grupos, um controle constituído de 11 RNT com peso adequado para a idade gestacional; e um grupo de 15 RN com peso abaixo do esperado para o termo (RNT-PIG. Do segundo grupo, 13 RN apresentaram algum tipo de alteração ao exame video-polissonográfico. As alterações mais frequentes foram na arquitetura do sono, 11 casos, e no comportamento, em que oito RN apresentaram número excessivo de sobressaltos ("startle" em relação ao grupo controle e dois RN uma atividade motora reduzida. Os resultados deste estudo demonstram a utilidade da video-polissonografia quando aplicada a RNT-PIG. O exame mostrou-se sensível em detectar diferenças no comportamento, arquitetura do sono e padrão eletrencefalográfico dos RNT-PIG quando comparados ao grupo controle.Video-polygraphic-EEG studies were performed in the first 24 life-hours of 26 healthy full-term newborns without perinatal injuries. The neurological examination and cranial ultrasonography were normal. The newborns were divided into two groups: one, with full-term appropriate - birth weight 11 newborns (control group and the other with full-term low-birth weight 15 newborns. Thirteen newborns of the second group had video-polygraphic-EEG study abnormalities. The most frequent abnormalities were found in 11 cases, as far as sleep architecture is concerned. Also, when compared with the control group, 8 cases of an excessive amount of startles and 2 cases of low behavior activities were found. The results demonstrate the usefulness of video-polygraphic-EEG study in the full-term newborns with intra-uterine growth retard. This examination was sensitive to detect behavior, sleep architecture and EEG standard differences in the low birth

  10. Cisão de cadeia na degradação termo-mecânica do poliestireno sob múltiplas extrusões Scission in the thermo mechanical degradation of polystyrene under multiple extrusions

    Directory of Open Access Journals (Sweden)

    Carlos A. Cáceres

    2008-01-01

    Full Text Available Determinou-se o número de cisões de cadeia gerado pela degradação termo-mecânica do poliestireno quando submetido a múltiplas extrusões. A degradação foi acompanhada pelas mudanças nas curvas de distribuição de massa molar. Seguindo-se o significado físico das massas molares médias de uma curva de MWD mostrou-se que a massa molar numérica media Mn é a única que pode ser relacionada diretamente com o número de moléculas do sistema. A partir desta calculou-se o número de cadeias clivadas (ns como uma relação entre a Mn da amostra degradada e a virgem. A função de distribuição de cisão de cadeia (CSDF mostra que o processo de degradação termo-mecânica do poliestireno submetido a múltiplas extrusões à 240 °C é do tipo aleatório, independente da massa molar inicial.The number of chain scissions during thermo-degradation of polystyrene under multiple extrusions was calculated. The degradation produces changes in the molecular weight distribution MWD curves. Following the physical meaning of the average molecular weights of a MWD curve it was shown that the number average molecular weight Mn is the only average that can be directly related to the number of molecules in the system. From that it was calculated the number of sectioned chains (ns as a ratio between the number of chains in the degraded and original polymers. The chain scission distribution function (CSDF shows that the thermo-mechanical degradation process of polystyrene under multiple extrusions at 240 °C is of a random type, independent of the initial molecular weight.

  11. Building a crystal palace

    CERN Multimedia

    2007-01-01

    The end-caps of the CMS electromagnetic calorimeter (ECAL) take shape as the first quadrant was completed on Wednesday 3 October. 1831 crystals, organised into five by five blocks named ‘supercrystals’, make up the first quadrant of Dee 1.With the 61,200-crystal barrel of its electromagnetic calorimeter (ECAL) complete, CMS is now building the endcaps, on the tenth anniversary of their initial design. Crystals for the endcaps were the last to be made, so the race is now on to have them all in place and ready for the turn-on of the LHC next year. Assembly of the first of eight quadrants began in June and crystal mounting was completed on Wednesday 3 October. Each crystal is transparent, has a volume just larger than a CERN coffee cup yet weighs a huge 1.5kg. 1831 of these lead tungstate crystals went into the first quadrant from a total 14,648 in the endcaps. The lead and tungsten account for 86% of each crystal’s weight, but as project leader Dave Cockerill expl...

  12. Padrão e ritmo de aquisição das habilidades motoras de lactentes pré-termo nos quatro primeiros meses de idade corrigida Pattern and rate of motor skill acquisition among preterm infants during the first four months corrected age

    Directory of Open Access Journals (Sweden)

    Elaine P. Raniero

    2010-10-01

    Full Text Available OBJETIVOS: Este estudo objetivou caracterizar o padrão e o ritmo de aquisição das habilidades motoras de lactentes nascidos pré-termo nos quatro primeiros meses de idade corrigida, comparando-os com um grupo de lactentes a termo. MÉTODOS: Participaram do estudo 12 lactentes pré-termo saudáveis, (MD=33,6 semanas de idade gestacional, ± 1,25 e 10 lactentes a termo saudáveis (MD=39,1 semanas de idade gestacional, ± 0,73. Eles foram avaliados mensalmente (zero a quatro meses de idade com o Test of Infant Motor Performance (TIMP. RESULTADOS: O padrão de desempenho motor aumentou ao longo dos meses em ambos os grupos, constatando variabilidade nos escores totais em todas as idades. O grupo pré-termo apresentou escore médio mais elevado do que o a termo entre um e quatro meses de idade. Nesse grupo, o ritmo de aquisição motora foi maior de zero a um do que de três a quatro meses. Verificou-se também que os cuidadores desses lactentes iniciaram a estimulação com brinquedos anteriormente aos cuidadores do grupo a termo. Ambos os grupos apresentaram escores médios inferiores aos do TIMP. CONCLUSÕES: Os lactentes pré-termo apresentaram padrão de desenvolvimento motor semelhante aos típicos quanto à sequência de habilidades adquiridas e ritmo acelerado no período de recém-nascido (RN a um mês de idade. Sugere-se que lactentes pré-termo com essas características não necessitam de correção do grau de prematuridade e que programas de acompanhamento orientem os pais e cuidadores a estimulá-los, desde o primeiro mês, com brinquedos, propiciando a exploração precoce de diversos padrões motores.OBJECTIVES: This study aimed to characterize the pattern and rate of motor skill acquisition among preterm infants from newborn to four months corrected age, in comparison with a group of full-term infants. METHODS: Twelve healthy preterm infants (mean gestational age=33.6 weeks ± 1.25 and 10 healthy full-term infants (mean

  13. Do termo à estruturação semântica: representação ontológica do domínio da Nanociência e Nanotecnologia utilizando a Estrutura Quali

    Directory of Open Access Journals (Sweden)

    Deni Yuzo Kasama

    2011-01-01

    Full Text Available O presente artigo apresenta as etapas de elaboração de uma ontologia do domínio da Nanociência e Nanotecnologia com vistas à sistematização do léxico dessa área de especialidade, por meio de formalismos descritos na Teoria do Léxico Gerativo, com ênfase na Estrutura Qualia e seus quatro papéis semânticos, a saber: Formal, Constitutivo, Agentivo e Télico. A partir de um córpus da área, e valendo-nos de métodos semiautomáticos para a extração de candidatos a termos e identificação de relações semânticas, delineamos um mapeamento semântico partindo de relações de herança conceitual, cuja representação foi feita em linguagem OWL, com o auxílio da ferramenta Protégé. 

  14. Consentindo ambigüidades: uma análise documental dos termos de consentimento informado, utilizados em clínicas de reprodução humana assistida

    Directory of Open Access Journals (Sweden)

    Vera Mincoff Menegon

    Full Text Available Elegendo a reprodução humana assistida como estudo de caso, este artigo apresenta resultados de pesquisa realizada com termos de consentimento informado, que articulou a compreensão do uso de linguagens sociais - com ênfase na linguagem dos riscos - e suas implicações nas relações entre profissionais e clientes. A pesquisa qualitativa, na perspectiva da Psicologia Social, apoiou-se na abordagem teórica sobre práticas discursivas, compreendendo a linguagem dos riscos como uma linguagem que permite falar da aspiração de controle futuro dos riscos. Analisaram-se os textos de 27 formulários, cedidos por oito clínicas brasileiras. Além de entender especificidades lingüísticas, buscou-se responder à pergunta: o que está sendo consentido? Os resultados mostraram a ambigüidade desse documento, que pressupõe o uso da metáfora correr ou não correr riscos: ele pode ser democrático, burocrático ou mesmo autoritário; a comunicação de riscos e benefícios subsidia tanto o processo de tomada de decisão como dilui as responsabilidades pela rede relacional.

  15. Consentindo ambigüidades: uma análise documental dos termos de consentimento informado, utilizados em clínicas de reprodução humana assistida

    Directory of Open Access Journals (Sweden)

    Menegon Vera Mincoff

    2004-01-01

    Full Text Available Elegendo a reprodução humana assistida como estudo de caso, este artigo apresenta resultados de pesquisa realizada com termos de consentimento informado, que articulou a compreensão do uso de linguagens sociais - com ênfase na linguagem dos riscos - e suas implicações nas relações entre profissionais e clientes. A pesquisa qualitativa, na perspectiva da Psicologia Social, apoiou-se na abordagem teórica sobre práticas discursivas, compreendendo a linguagem dos riscos como uma linguagem que permite falar da aspiração de controle futuro dos riscos. Analisaram-se os textos de 27 formulários, cedidos por oito clínicas brasileiras. Além de entender especificidades lingüísticas, buscou-se responder à pergunta: o que está sendo consentido? Os resultados mostraram a ambigüidade desse documento, que pressupõe o uso da metáfora correr ou não correr riscos: ele pode ser democrático, burocrático ou mesmo autoritário; a comunicação de riscos e benefícios subsidia tanto o processo de tomada de decisão como dilui as responsabilidades pela rede relacional.

  16. Development of data acquisition system for test circuit for the Thermo-Hydraulic Laboratory of CDTN; Desenvolvimento de sistema de aquisicao de dados para circuito de testes do Laboratorio de Termo-Hidraulica do CDTN

    Energy Technology Data Exchange (ETDEWEB)

    Corrade, Thales Jose Rodrigues; Mesquita, Amir Zacarias; Santos, Andre Augusto Campagnole dos, E-mail: thalescorrade@hotmail.com, E-mail: amir@cdtn.br, E-mail: aacs@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico de Tecnologia de Reatores

    2013-07-01

    The Circuit Water-Air (CWA), present in the Laboratorio de Termo-Hidraulica of the Centro de Desenvolvimento da Tecnologia Nuclear/Comissao Nacional de Energia Nuclear (CDTN / CNEN), has been used to evaluate devices present in nuclear fuel elements of a PWR (Pressurized Water Reactor). Currently, a segment of 5x5 beam simulators grids with spacer bars is being tested, serving one of the activities under the Project FUJB / FINEP / INB - 'Development of New Generation of Nuclear Fuel Element '. For the measurements of pressure drop along this beam, a system of data acquisition based on Basic language was created. Although this system is efficient and robust, their resources are very limited. Therefore, it was decided to use the software LabVIEW® implementing a more versatile and modern system. This article describes the new data acquisition system, and presents some results. The main parameters are monitored: temperature, density, dynamic viscosity, Reynolds number. The values of standard deviation, mean and uncertainty of an arbitrary channel are calculated. The system was installed and tested in the circuit under experimental conditions and showed satisfactory results.

  17. Ruptura prematura das membranas amnióticas no pré-termo: fatores associados à displasia broncopulmonar Preterm premature rupture of the fetal membranes: factors associated with bronchopulmonary dysplasia

    Directory of Open Access Journals (Sweden)

    Danieli Dias Gonçalves

    2010-10-01

    Full Text Available OBJETIVO: identificar os fatores obstétricos e neonatais associados ao desfecho de displasia broncopulmonar em pacientes com amniorrexe prematura no pré-termo. MÉTODOS: foram analisados 213 prontuários do Instituto Fernandes Figueira, entre 1998 e 2002, cujas pacientes evoluíram com quadro de amniorrexe prematura 10 dias (OR: 54,00 [11,55-278,25] p=0,000; idade gestacional 10 dias (p=0,001 e "uso de surfactante" (p=0,040 permaneceram independentemente associadas ao desfecho. CONCLUSÕES: observou-se que os fatores associados à displasia broncopulmonar são de natureza neonatal, sendo que a ventilação mecânica duradoura e o uso de surfactante neonatal influenciaram no desenvolvimento dessa doença.PURPOSE: to analyze obstetric and neonatal factors associated with bronchopulmonary dysplasia outcome in patients with preterm premature amniorrhexis. METHODS: we analyzed 213 medical records of patients of Fernandes Figueira Institute who suffered premature amniorrhexis (10 days (p=0.001 and "use of a surfactant" (p=0.040 remained independently associated with bronchopulmonary dysplasia. CONCLUSIONS: the factors associated with bronchopulmonary dysplasia are related to neonatal features, asprolonged mechanical ventilation and the use of a surfactant influencethe development of thedisease.

  18. Desenvolvimento mental e motor aos 24 meses de crianças nascidas a termo com baixo peso Mental and motor development at 24 months of full-term low birthweight infants

    Directory of Open Access Journals (Sweden)

    Sophie Helena Eickmann

    2002-09-01

    Full Text Available Este estudo teve como objetivo comparar o desenvolvimento aos 24 meses de 152 crianças nascidas a termo, com baixo peso (The objective of this study was to compare the development at 24 months of 152 full-term infants, born with low (<2500g and appropriate birth weight (3000 to 3499g, paired in a proportion of 1:1 by sex and age. Mental and motor development were assessed through the Bayley scale. A variety of sociodemographic and environmental stimulation conditions were also assessed. The infants born with low weight had on average significantly lower mental and motor indexes than those born with appropriate weight (p<0.001, with a difference of 9.1 and 10.2 points, respectively. The multiple linear regression analysis showed that socioeconomic conditions and environmental stimulation explained 11% and 12% of the variation of mental index, and 12% and 9% of motor development, respectively. All together, they explained 23% and 21% of the variation of these indexes. Low birth weight influenced only 3% of the variation of mental index and 5% of motor index.

  19. Desenvolvimento motor e funcional em crianças nascidas pré-termo e a termo: influência de fatores de risco biológico e ambiental Desarrollo motor y funcional en niños nacidos pretérmino y a término: influencia de factores de riesgo biológico y ambiental Motor and functional development in infants born preterm and full term: influence of biological and environmental risk factors

    Directory of Open Access Journals (Sweden)

    Edifrance Sá de Souza

    2012-12-01

    Full Text Available OBJETIVO: Comparar o desenvolvimento motor de crianças de 12 a 18 meses nascidas pré-termo e a termo e investigar sua relação com o desempenho funcional e com a quantidade e qualidade de estímulos ambientais. MÉTODOS: Estudo quantitativo e longitudinal com 30 crianças prematuras (idade gestacional de 30,0±2,3 semanas e peso ao nascimento de 1178±193g e 30 nascidas a termo (idade gestacional de 39,0±1,3 semanas e peso ao nascimento de 3270±400g. O desenvolvimento motor foi avaliado pelos testes Alberta Infant Motor Scale e Peabody Developmental Motor Scales. O ambiente domiciliar foi avaliado com o Home Observation Measurement of the Environment. Com o intuito de examinar as habilidades funcionais, utilizou-se o Pediatric Evaluation of Disability Inventory. RESULTADOS: Houve maior lentidão para aquisição da marcha no grupo pré-termo (p=0,005, embora não tenha sido encontrada diferença significativa entre os grupos no Alberta Infant Motor Scale aos 12 (p=0,19 e aos 15 meses (p=0,80. Aos 18 meses foram encontradas diferenças significativas no desenvolvimento motor grosso (pOBJETIVO: Comparar el desarrollo motor de los 12 a los 18 meses de niños nacidos pretérmino y a término e investigar la relación entre desarrollo motor, desempeño funcional y la cantidad y calidad de estímulos ambientales. MÉTODOS: Estudio cuantitativo, direccional y longitudinal, que incluyó a 30 niños prematuros (edad gestacional: 30,0±2,3 semanas y peso al nacer: 1178±193 gramas y 30 nacidos a término (edad gestacional: 39,0±1,3 semanas y peso al nacer: 3270±400 gramas. El desarrollo motor fue evaluado con el uso de las pruebas Alberta Infant Motor Scale (AIMS y Peabody Developmental Motor Scales (PDMS-2. El ambiente domiciliar fue evaluado con el Home Observation Measurement of the Enviroment (HOME. Para examinar las habilidades funcionales se utilizó el Pediatric Evaluation of Disability Inventory (PEDI. RESULTADOS: Hubo mayor lentitud para

  20. Time crystals: a review

    Science.gov (United States)

    Sacha, Krzysztof; Zakrzewski, Jakub

    2018-01-01

    Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications of discrete (or Floquet) time crystals—the structures that appear in the time domain due to spontaneous breaking of discrete time translation symmetry. The struggle to observe discrete time crystals is reviewed here together with propositions that generalize this concept introducing condensed matter like physics in the time domain. We shall also revisit the original Wilczek’s idea and review strategies aimed at spontaneous breaking of continuous time translation symmetry.

  1. Thermodynamics of Crystals

    Science.gov (United States)

    Navrotsky, Alexandra

    Thermodynamics of Crystals is a gold mine of a references bargain with more derivations of useful equations per dollar, or per page, than almost any other book I know. Useful to whom? To the solid state physicist, the solid state chemist working the geophysicist, the rock mechanic, the mineral physicist. Useful for what? For lattice dynamics, crystal potentials, band structure. For elegant, rigorous, and concise derivations of fundamental equations. For comparison of levels of approximation. For some data and physical insights, especially for metals and simple halides. This book is a reissue, with some changes and additions, of a 1970 treatise. It ages well, since the fundamentals do not change.

  2. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    Photonic crystal fibres represent one of the most active research areas today in the field of optics. The diversity of applications that may be addressed by these fibres and their fundamental appeal, by opening up the possibility of guiding light in a radically new way compared to conventional...... optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...

  3. The Crystal Hotel: A Microfluidic Approach to Biomimetic Crystallization.

    Science.gov (United States)

    Gong, Xiuqing; Wang, Yun-Wei; Ihli, Johannes; Kim, Yi-Yeoun; Li, Shunbo; Walshaw, Richard; Chen, Li; Meldrum, Fiona C

    2015-12-02

    A "crystal hotel" microfluidic device that allows crystal growth in confined volumes to be studied in situ is used to produce large calcite single crystals with predefined crystallographic orientation, microstructure, and shape by control of the detailed physical environment, flow, and surface chemistry. This general approach can be extended to form technologically important, nanopatterned single crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hydrothermally grown zeolite crystals

    International Nuclear Information System (INIS)

    Durrani, S.K.; Qureshi, A.H.; Hussain, M.A.; Qazi, N.K.

    2009-01-01

    The aluminium-deficient and ferrosilicate zeolite-type materials were synthesized by hydrothermal process at 150-170 degree C for various periods of time from the mixtures containing colloidal reactive silica, sodium aluminate, sodium hydroxide, iron nitrate and organic templates. Organic polycation templates were used as zeolite crystal shape modifiers to enhance relative growth rates. The template was almost completely removed from the zeolite specimens by calcination at 550 degree C for 8h in air. Simultaneous thermogravimetric (TG) and differential thermal analysis (DTA) was performed to study the removal of water molecules and the amount of organic template cations occluded inside the crystal pore of zeolite framework. The 12-13% weight loss in the range of (140-560 degree C) was associated with removal of the (C/sub 3/H/sub 7/)/sub 4/ N+ cation and water molecules. X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) techniques were employed to study the structure, morphology and surface features of hydrothermally grown aluminium-deficient and ferrosilicate zeolite-type crystals. In order to elucidate the mode of zeolite crystallization the crystallinity and unit cell parameters of the materials were determined by XRD, which are the function of Al and Fe contents of zeolites. (author)

  5. Poet Lake Crystal Approval

    Science.gov (United States)

    This September 19, 2016 letter from EPA approves the petition from Poet Biorefining-Lake Crystal, regarding non-grandfathered ethanol produced through a dry mill process, qualifying under the Clean Air Act for renewable fuel (D-code 6) RINs under the RFS

  6. Liquid crystal display

    International Nuclear Information System (INIS)

    Takami, K.

    1981-01-01

    An improved liquid crystal display device is described which can display letters, numerals and other necessary patterns in the night time using a minimized amount of radioactive material. To achieve this a self-luminous light source is placed in a limited region corresponding to a specific display area. (U.K.)

  7. Soap Bubbles and Crystals

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 6. Soap Bubbles and Crystals. Jean E Taylor. General Article Volume 11 Issue 6 June 2006 pp 26-30. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/011/06/0026-0030. Keywords. Soap bubble ...

  8. Agile Photonic Crystals

    Science.gov (United States)

    2011-01-03

    75, pp. 3253-3256, Oct. 1995. [24] F. Benabid, J. C. Knight, and P. S. J. Russell, “Particle levitation and guidance in hollow-core photonic crystal...B. Mizaikoff, “Midinfrared sensors meet nanotechnology: Trace gas sensing with quantum cascade lasers inside photonic band-gap hollow waveguides

  9. The Crystal Set

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2014-01-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…

  10. WORKSHOP: Scintillating crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-12-15

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry.

  11. The CMS crystal calorimeter

    CERN Document Server

    Lustermann, W

    2004-01-01

    The measurement of the energy of electrons and photons with very high accuracy is of primary importance far the study of many physics processes at the Large Hadron Collider (LHC), in particular for the search of the Higgs Boson. The CMS experiment will use a crystal calorimeter with pointing geometry, almost covering 4p, as it offers a very good energy resolution. It is divided into a barrel composed of 61200 lead tungstate crystals, two end-caps with 14648 crystals and a pre-shower detector in front of the end-cap. The challenges of the calorimeter design arise from the high radiation environment, the 4 Tesla magnetic eld, the high bunch crossing rate of 40 MHz and the large dynamic range, requiring the development of fast, radiation hard crystals, photo-detectors and readout electronics. An overview of the construction and design of the calorimeter will be presented, with emphasis on some of the details required to meet the demanding performance goals. 19 Refs.

  12. Positrons in ionic crystals

    International Nuclear Information System (INIS)

    Pareja, R.

    1988-01-01

    Positron annihilation experiments in ionic crystals are reviewed and their results are arranged. A discussion about the positron states in these materials is made in the light of these results and the different proposed models. The positronium in alkali halides is specially considered. (Author)

  13. WORKSHOP: Scintillating crystals

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry

  14. Thermoelectricity in liquid crystals

    Science.gov (United States)

    Mohd Said, Suhana; Nordin, Abdul Rahman; Abdullah, Norbani; Balamurugan, S.

    2015-09-01

    The thermoelectric effect, also known as the Seebeck effect, describes the conversion of a temperature gradient into electricity. A Figure of Merit (ZT) is used to describe the thermoelectric ability of a material. It is directly dependent on its Seebeck coefficient and electrical conductivity, and inversely dependent on its thermal conductivity. There is usually a compromise between these parameters, which limit the performance of thermoelectric materials. The current achievement for ZT~2.2 falls short of the expected threshold of ZT=3 to allow its viability in commercial applications. In recent times, advances in organic thermoelectrics been significant, improving by over 3 orders of magnitude over a period of about 10 years. Liquid crystals are newly investigated as candidate thermoelectric materials, given their low thermal conductivity, inherent ordering, and in some cases, reasonable electrical conductivity. In this work the thermoelectric behaviour of a discotic liquid crystal, is discussed. The DLC was filled into cells coated with a charge injector, and an alignment of the columnar axis perpendicular to the substrate was allowed to form. This thermoelectric behavior can be correlated to the order-disorder transition. A reasonable thermoelectric power in the liquid crystal temperature regime was noted. In summary, thermoelectric liquid crystals may have the potential to be utilised in flexible devices, as a standalone power source.

  15. Chemistry of microporous crystals

    International Nuclear Information System (INIS)

    Inui, Tomoyuki; Namba, Seitaro; Tatsumi, Takashi

    1991-01-01

    This volume contains three papers which are in INIS scope, entitled respectively: 129 Xe-NMR study of the crystallization of SAPO-37, NMR studies of cation localization in zeolites, developments in x-ray and neutron diffraction methods for zeolites. (H.W.). refs.; figs.; tabs

  16. Neurocomportamento de recém-nascidos a termo, pequenos para a idade gestacional, filhos de mães adolescentes Neurobehavior of full-term small for gestational age newborn infants of adolescent mothers

    Directory of Open Access Journals (Sweden)

    Marina C. de Moraes Barros

    2008-06-01

    Full Text Available OBJETIVO: Comparar o neurocomportamento de recém-nascidos a termo pequenos (PIG e adequados (AIG para a idade gestacional, filhos de mães adolescentes. MÉTODOS: Estudo transversal prospectivo de nascidos a termo AIG e PIG, com 24-72 horas de vida, sem afecções do sistema nervoso central. Os neonatos foram avaliados por meio da Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS para: habituação, atenção, despertar, controle, manobras para a orientação, qualidade dos movimentos, excitabilidade, letargia, reflexos não ótimos, assimetria, hipertonia, hipotonia e sinais de estresse e abstinência. A comparação dos grupos AIG e PIG foi feita por análise de variância e teste do qui-quadrado. Aplicou-se a regressão multivariada para analisar os fatores associados ao escore de cada variável do NNNS. RESULTADOS: Dos 3.685 nascidos no local do estudo, 928 (25% eram de mães adolescentes. Desses, 477 satisfizeram os critérios de inclusão, sendo 419 (88% AIG e 58 (12% PIG. A análise univariada não mostrou diferença em nenhuma das variáveis da NNNS entre os PIG e os AIG. Na análise multivariada, os PIG nascidos de parto vaginal apresentaram menor escore na variável qualidade de movimentos do que os nascidos por cesárea. Os PIG nascidos com anestesia local ou sem anestesia apresentaram maior escore na variável excitabilidade do que os nascidos sob anestesia loco-regional. Os PIG femininos tiveram menor escore na variável sinais de estresse/abstinência que os masculinos. CONCLUSÃO: Os recém-nascidos PIG de mães adolescentes mostraram menor qualidade de movimento, mais excitabilidade e mais sinais de estresse, em associação com o sexo do neonato e com variáveis relacionadas ao parto.OBJECTIVE: To compare the neurobehavior of small (SGA and adequate (AGA for gestational age full-term neonates born to adolescent mothers. METHODS: This prospective cross-sectional study included full-term newborn infants aged 24

  17. Prevalence of dental caries in children born prematurely or at full term Prevalência de cárie dentária em crianças nascidas prematuramente e a termo

    Directory of Open Access Journals (Sweden)

    Danuze Batista Lamas Gravina

    2006-12-01

    Full Text Available The objective of this study was to evaluate the prevalence of dental caries in 192 children, 96 born prematurely and 96 at full term, in a regional hospital in Brazil. Mean age at clinical examination was 40.72 months in the full-term group (G1 and 30.44 months in the premature group (G2. The children were divided in two age subgroups: 0 to 3 and 4 to 6 years. Statistical results (Student's t and Kruskal-Wallis tests showed that dmft was 0.43 for G1 and 0.01 for G2 in the 0-3 age subgroup, and 1.7 for G1 and 1.1 for G2 in the 4-6 age subgroup. Differences were significant between G1 and G2 only in the 0-3 age subgroup (p = 0.047. Caries evaluation showed that, of the 96 children in G1, 75 were caries free, while in G2, 84 did not have the disease. These differences were not significant (p = 0.088. The lower mean dmft found in the 0-3 age subgroup in G2 may be attributed to routines established by the hospital's neonatology staff, such as frequent dental visits and preventive instructions about oral habits, oral hygiene and diet. After this age, with the completion of the primary dentition, values increased and became similar between the G1 and G2 groups. Results also suggested a highly skewed distribution since most caries were found in only a small number of children.O objetivo deste estudo foi avaliar a prevalência da cárie dentária em 192 crianças, 96 nascidas prematuramente e 96 a termo, em um hospital regional no Brasil. A média de idade ao exame clínico foi de 40,72 meses e 30,44 meses para os grupos a termo (G1 e prematuro (G2, respectivamente. As crianças foram divididas em faixas etárias de 0 a 3 e 4 a 6 anos. Os resultados estatísticos (testes t de Student e Kruskal-Wallis mostraram que, entre 0 a 3 anos, o ceo-d foi 0,43 para o G1 e 0,01 para o G2. Entre 4 e 6 anos, o ceo-d foi 1,7 e 1,1 para G1 e G2, respectivamente. Os resultados foram significativos entre G1 e G2 apenas na faixa etária entre 0 e 3 anos (p = 0,047. A

  18. Avaliação neurológica de recém-nascidos pré-termo de muito baixo peso com displasia broncopulmonar Neurological assessment of very low birth weight infants with bronchopulmonary dysplasia

    Directory of Open Access Journals (Sweden)

    Tathiana Ghisi de Souza

    2009-03-01

    Full Text Available OBJETIVO: Descrever e comparar a avaliação neurológica e comportamental de recém-nascidos pré-termos com e sem displasia broncopulmonar (DBP. MÉTODOS: Recém-nascidos prematuros com peso ao nascer inferior a 1500g e idade gestacional menor de 32 semanas foram avaliados com 40 semanas de idade gestacional corrigida, no Centro de Atenção Integral à Saúde da Mulher da Universidade Estadual de Campinas. Utilizou-se a Avaliação Neurológica de Dubowitz, com 29 itens divididos em seis categorias: tônus, padrões de tônus, reflexos, movimentos, sinais anormais e comportamento. O estado de consciência do recém-nascido foi graduado segundo Brazelton (1973. Utilizaram-se os testes do qui-quadrado e exato de Fischer para variáveis qualitativas e o de Mann-Whitney para as numéricas não-paramétricas, com nível de significância de 5%. RESULTADOS: No período de janeiro de 2005 a setembro de 2007, 24 recém-nascidos, 12 com DBP e 12 controles, com idade gestacional ao nascer de 28±1 semana e peso de 884±202g no grupo com DBP e 31±1 semana e 1156±216g no Grupo Controle foram avaliados. Dos 29 itens avaliados, 18 foram homogêneos entre os grupos e a pontuação geral dos dois grupos não apresentou diferença (p=0,30. Observou-se maior anormalidade neurológica no grupo com DBP em oito itens e, no Grupo Controle, em três itens. CONCLUSÕES: A comparação da avaliação neurológica de Dubowitz de recém-nascidos pré-termos com e sem DBP não apresentou diferença significante com 40 semanas de idade gestacional corrigida. Nas categorias reflexos e postura/tônus, observou-se tendência a anormalidade no grupo DBP.OBJECTIVE: To compare the neurological assessment of preterm newborn infants with and without bronchopulmonary dysplasia (BPD. METHODS: Preterm newborn infants with birth weight less than 1,500g and gestational age less than 32 weeks were evaluated by Dubowitz Method at 40 weeks of corrected gestational age. All infants

  19. Electrical properties of molecular crystals

    International Nuclear Information System (INIS)

    Barraud, A.

    1968-01-01

    This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [fr

  20. Comportamento de lactentes nascidos a termo pequenos para a idade gestacional no primeiro trimestre da vida Behavior of full term infants small for gestational age in the first three months of life

    Directory of Open Access Journals (Sweden)

    Bernadete Balanin A. Mello

    2004-12-01

    Full Text Available O objetivo foi comparar o comportamento de lactentes nascidos a termo com peso adequado (AIG a lactantes pequenos para a idade gestacional (PIG, no primeiro trimestre de vida. A amostra foi de 20 lactentes, avaliados no 1º, 2º e 3º meses. Foram utilizadas as Escalas Bayley de Desenvolvimento Infantil - II, com ênfase na Escala de Classificação do Comportamento (ECC. Houve diferença significativa entre os grupos no 2º mês, com maior número de lactentes PIG classificados como alterados na ECC. O Fator Qualidade Motora demonstrou valores da mediana significativamente menores no grupo PIG, nos itens Motricidade Axial, Controle de Movimentos e Hipertonia Muscular. O Fator Atenção/Vigília não mostrou diferença entre os grupos. Entretanto, quando analisados os itens Exploração de Objetos e de Ambiente e Interação com o Examinador, houve diferença significativa no 2º mês, com valores da mediana menores no grupo PIG.The objective was to compare the behavior of full-term infants small-for-gestational age (SGA with full-term appropriate-for-gestational age (AGA. The sample considered 20 infants in the 1st, 2nd and in the 3rd months of life. The Bayley Scales of Infant Development-II were used, with attention to items related to Behavior Rate Scale (BRS. It was found that SGA infants showed lower average values in the BRS in the 2nd month. The Motor Quality Factor displayed significantly lower average values in SGA group, in the items Gross-motor Movement Required by Tasks, Control of Movements and Hypertonicity. The Attention/Arousal Factor in the items Exploration of Objects/Surroundings and Orientation to Examiner displayed significantly lower average values in the SGA group.

  1. Extração automática de candidatos a termos do Curso de Linguística Geral com apoio de recursos da Linguística de Corpus e do Processamento de Linguagem Natural

    Directory of Open Access Journals (Sweden)

    Lucelene Lopes

    2015-12-01

    Full Text Available Este trabalho apresenta um estudo em que técnicas de Processamento de Linguagem Natural (PLN e de Linguística de Corpus (LC são utilizadas para extrair e estruturar termos relacionados a conceitos importantes de Saussure no texto em português do Curso de Linguística Geral (CLG. Tomando o CLG como um corpus, busca-se um método de representação automática de conteúdo através de ferramentas computacionais. Uma vez submetido ao parser PALAVRAS, um etiquetador morfossintático para a língua portuguesa, o corpus do CLG é processado pela ferramenta extratora de sintagmas nominais relevantes, denominada ExATOlp, que implementa diversas técnicas de PLN de base linguística e de base estatística. Em seguida, são geradas listas e gráficos hierarquizados dos sintagmas nominais do CLG, elencados pela ferramenta como os mais específicos/relevantes do corpus em questão. Esses resultados são comparados com dados gerados pela ferramenta AntConc, ferramenta de acesso livre bastante empregada em trabalhos de LC, aplicada ao mesmo corpus. Os resultados mostram o potencial da ferramenta ExATOlp para trabalhos em LC e para o levantamento de dados lexicais para estudos terminológicos, para a mineração de dados e para a geração de ontologias em língua portuguesa.

  2. Estudo da proporcionalidade corporal de recém-nascidos a termo segundo o Índice Ponderal de Rohrer e grau de retardo de crescimento intra-uterino

    Directory of Open Access Journals (Sweden)

    José Carneiro Leão Filho

    2003-12-01

    Full Text Available Trata-se de estudo do tipo observacional, de corte transversal, para descrever as características antropométricas e proporcionalidade corporal de 549 recém-nascidos a termo (RNT. As medidas antropométricas usadas foram: peso (P, comprimento (C, perímetro cefálico (PC, índice ponderal de Rohrer (IP, razão peso/perímetro cefálico (P/PC e razão comprimento/ perímetro cefálico (C/PC. Também foi estudada a severidade do retardo de crescimento intra-uterino (RCIU, através da distribuição do escore z quanto ao desvio do peso ao nascer. Os recém-nascidos pequenos para idade gestacional (PIG foram definidos como aqueles com escore z < -2, e o ponto de corte do IP, P/PC e C/PC foi definido como a média menos 1 desvio-padrão na população local de referência. De acordo com o IP, 72,8% dos PIG e 12,8% dos adequados para idade gestacional (AIG foram classificados como desproporcionais. Segundo o C/PC, 25,6% dos PIG e 11,6% dos AIG foram classificados como desproporcionais, o que ocorreu com todos os PIG e 16,3% dos AIG quando se usou a P/PC. Em todos os critérios, observou-se tendência linear significativa para aumento da desproporcionalidade à medida que aumenta o grau de severidade do RCIU.

  3. Estudo da proporcionalidade corporal de recém-nascidos a termo segundo o Índice Ponderal de Rohrer e grau de retardo de crescimento intra-uterino

    Directory of Open Access Journals (Sweden)

    Leão Filho José Carneiro

    2003-01-01

    Full Text Available Trata-se de estudo do tipo observacional, de corte transversal, para descrever as características antropométricas e proporcionalidade corporal de 549 recém-nascidos a termo (RNT. As medidas antropométricas usadas foram: peso (P, comprimento (C, perímetro cefálico (PC, índice ponderal de Rohrer (IP, razão peso/perímetro cefálico (P/PC e razão comprimento/ perímetro cefálico (C/PC. Também foi estudada a severidade do retardo de crescimento intra-uterino (RCIU, através da distribuição do escore z quanto ao desvio do peso ao nascer. Os recém-nascidos pequenos para idade gestacional (PIG foram definidos como aqueles com escore z < -2, e o ponto de corte do IP, P/PC e C/PC foi definido como a média menos 1 desvio-padrão na população local de referência. De acordo com o IP, 72,8% dos PIG e 12,8% dos adequados para idade gestacional (AIG foram classificados como desproporcionais. Segundo o C/PC, 25,6% dos PIG e 11,6% dos AIG foram classificados como desproporcionais, o que ocorreu com todos os PIG e 16,3% dos AIG quando se usou a P/PC. Em todos os critérios, observou-se tendência linear significativa para aumento da desproporcionalidade à medida que aumenta o grau de severidade do RCIU.

  4. Optimization of photonic crystal cavities

    DEFF Research Database (Denmark)

    Wang, Fengwen; Sigmund, Ole

    2017-01-01

    We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....

  5. Production of polarizing Heusler crystals

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, P. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1999-11-01

    Heusler crystals simultaneously produce monochromatized and polarized neutrons. However, in the past, it was difficult to produce these crystals. In collaboration with the neutron scattering group of CEA Grenoble and LLB Saclay, the production of high quality Heusler crystals has been established at ILL. (author) 3 refs., 2 figs., 1 tab.

  6. Níveis de ferro, cobre e zinco em colostro de puérperas adultas de recém-nascidos a termo e pré-termo, segundo variáveis maternas e socioeconômicas Levels of iron, copper and zinc in the colostrum of adult puerpera of term and pre-term infants, as a function of maternal and socioeconomic variables

    Directory of Open Access Journals (Sweden)

    Roseli S. S. da Costa

    2002-04-01

    Full Text Available OBJETIVOS: descrever os níveis de Fe, Cu e Zn em amostras de colostro de puérperas adultas brasileiras de recém-nascidos a termo (RNAT e pré-termo (RNPT e avaliar a influência das variáveis maternas (idade materna, estado nutricional pré-gestacional, paridade, intercorrências gestacionais, renda familiar per capita e condições de saneamento sobre os níveis desses oligoelementos, visando apontar as mulheres em risco de produzirem colostro com menores níveis destes minerais. MÉTODOS: coletaram-se 50 amostras de colostro de puérperas de RNAT e 38 de puérperas de RNPT, do Instituto Fernandes Figueira, Rio de Janeiro, RJ, Brasil. Os oligoelementos foram analisados através da técnica de Fluorescência de Raios X por Reflexão Total com radiação Síncrotron. RESULTADOS: os níveis de Fe nos grupos RNPT e RNAT foram semelhantes (p > 0,05. As concentrações de Cu foram maiores no colostro de RNPT (p OBJECTIVES: to investigate the concentrations of Fe, Cu and Zn in samples of colostrum from Brazilian adult women puerpera of term infants (TI and pre-term infants (PTI and to evaluate the influence of some maternal variables (age, pre-pregnancy nutritional status, parity, maternal health alterations during the gestational period, per capita familiar income and living conditions on the concentration of those elements, aiming to identify the women who were prone to produce colostrum with low levels of oligoelements. METHODS: 50 samples of colostrum from puerpera of TI and 38 from puerpera of PTI were collected from women interned at Instituto Fernandes Figueira, Rio de Janeiro, RJ, Brazil. The levels of trace elements were determined by Total Reflection X-ray Fluorescence Analysis (TXRF with Synchrotron Radiation. RESULTS: no differences were observed in the Fe levels between PTI and TI groups (p > 0,05. The Cu concentrations were higher in the PTI colostrum (p < 0,05 and those of Zn were higher in the TI colostrum (p < 0,05. We observed

  7. Graphene-based photonic crystal

    International Nuclear Information System (INIS)

    Berman, Oleg L.; Boyko, Vladimir S.; Kezerashvili, Roman Ya.; Kolesnikov, Anton A.; Lozovik, Yurii E.

    2010-01-01

    A novel type of photonic crystal formed by embedding a periodic array of constituent stacks of alternating graphene and dielectric discs into a background dielectric medium is proposed. The photonic band structure and transmittance of such photonic crystal are calculated. The graphene-based photonic crystals can be used effectively as the frequency filters and waveguides for the far infrared region of electromagnetic spectrum. Due to substantial suppression of absorption of low-frequency radiation in doped graphene the damping and skin effect in the photonic crystal are also suppressed. The advantages of the graphene-based photonic crystal are discussed.

  8. Liquid crystals in tribology.

    Science.gov (United States)

    Carrión, Francisco-José; Martínez-Nicolás, Ginés; Iglesias, Patricia; Sanes, José; Bermúdez, María-Dolores

    2009-09-18

    Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs), only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs). Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.

  9. Liquid crystal dimers

    CERN Document Server

    Kumar Pal, Santanu

    2017-01-01

    This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

  10. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    Despite the general recession in the global economy and the collapse of the optical telecommunication market, research within specialty fibers is thriving. This is, more than anything else, due to the technology transition from standard all-glass fibers to photonic crystal fibers, which, instead....... The freedom to design the dispersion profile of the fibers is much larger and it is possible to create fibers, which support only a single spatial mode, regardless of wavelength. In comparison, the standard dispersion-shifted fibers are limited by a much lower index-contrast between the core and the cladding...... in 1996, and are today on their way to become the dominating technology within the specialty fiber field. Whether they will replace the standard fiber in the more traditional areas like telecommunication transmission, is not yet clear, but the nonlinear photonic crystal fibers are here to stay....

  11. Liquid crystal colloids

    CERN Document Server

    Muševič, Igor

    2017-01-01

    This book brings together the many concepts and discoveries in liquid crystal colloids contributed over the last twenty years and scattered across numerous articles and book chapters. It provides both a historical overview of the development of the field and a clear perspective on the future applications in photonics. The book covers all phenomena observed in liquid crystal colloids with an emphasis on experimental tools and applications of topology in condensed matter, as well as practical micro-photonics applications. It includes a number of spectacular manifestations of new topological phenomena not found or difficult to observe in other systems. Starting from the early works on nematic colloids, it explains the basics of topological defects in ordered media, charge and winding, and the elastic forces between colloidal particles in nematics. Following a detailed description of experimental methods, such as optical tweezing and particle tracking, the book eases the reader into the theoretical part, which de...

  12. Dosimetry for Crystals Irradiation

    CERN Document Server

    Lecomte, Pierre

    2005-01-01

    Before shipment to CMS, all PbWO4 crystals produced in China are irradiated there with 60 Co , in order to insure that the induced absorption coefficient is within specifications. Acceptance tests at CERNand at ENEA also include irradiation with gamma rays from 60 Co sources. There were initially discrepancies in quoted doses and doserates as well as in induced absorption coefficients. The present work resolves the discrepancies in irradiation measurements and defines common dosimetry methods for consistency checks between irradiation facilities.

  13. Crystals against cancer

    CERN Multimedia

    2009-01-01

    This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  14. On crystallization of law

    Directory of Open Access Journals (Sweden)

    Szmodis Jenő

    2014-01-01

    Full Text Available The article introduces the problem of autonomy of law. The paper examines the medieval origins of legal positivism from a historical approach, sketching the main theories concerning the emergence of law, and phrasing some preliminary consideration for a historical and philosophical view of the problem of the birth of law. As a result of reasoning the article suggests some legal historical and human ethological ideas relating to the phenomena of crystallization of the law.

  15. Phononic crystals fundamentals and applications

    CERN Document Server

    Adibi, Ali

    2016-01-01

    This book provides an in-depth analysis as well as an overview of phononic crystals. This book discusses numerous techniques for the analysis of phononic crystals and covers, among other material, sonic and ultrasonic structures, hypersonic planar structures and their characterization, and novel applications of phononic crystals. This is an ideal book for those working with micro and nanotechnology, MEMS (microelectromechanical systems), and acoustic devices. This book also: Presents an introduction to the fundamentals and properties of phononic crystals Covers simulation techniques for the analysis of phononic crystals Discusses sonic and ultrasonic, hypersonic and planar, and three-dimensional phononic crystal structures Illustrates how phononic crystal structures are being deployed in communication systems and sensing systems.

  16. Quartz crystal fabrication facility

    Science.gov (United States)

    Ney, R. J.

    1980-05-01

    The report describes the design and operation of a five chamber, interconnected vacuum system, which is capable of cleaning, plating, and sealing precision quartz crystal units in ceramic flatpack enclosures continuously in a high vacuum environment. The production rate design goal was 200 units per eight hour day. A unique nozzle beam gold deposition source was developed to operate for extended periods of time without reloading. The source puts out a narrow beam of gold typically in the order of 2 1/2 deg included cone angle. Maximum deposition rates are in the order of 400 a/min at 5.5 in. 'throw' distance used. Entrance and exit air lock chambers expedite the material throughput, so that the processing chambers are at high vacuum for extended periods of time. A stainless steel conveyor belt, in conjunction with three vacuum manipulators, transport the resonator components to the various work stations. Individual chambers are normally separated from each other by gate valves. The crystal resonators, mounted in flatpack frames but unplated, are loaded into transport trays in a lid-frame-lid sequency for insertion into the system and exit as completed crystal units. The system utilizes molybdenum coated ball bearings at essentially all friction surfaces. The gold sources and plating mask heads are equipped with elevators and gate valves, so that they can be removed from the system for maintenance without exposing the chambers to atmosphere.

  17. Slotted Photonic Crystal Sensors

    Science.gov (United States)

    Scullion, Mark G.; Krauss, Thomas F.; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  18. Slotted Photonic Crystal Sensors

    Directory of Open Access Journals (Sweden)

    Andrea Di Falco

    2013-03-01

    Full Text Available Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  19. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting.

  20. Unifying the crystallization behavior of hexagonal and square crystals with the phase-field-crystal model

    International Nuclear Information System (INIS)

    Yang Tao; Chen Zheng; Zhang Jing; Wang Yongxin; Lu Yanli

    2016-01-01

    By employing the phase-field-crystal models, the atomic crystallization process of hexagonal and square crystals is investigated with the emphasis on the growth mechanism and morphological change. A unified regime describing the crystallization behavior of both crystals is obtained with the thermodynamic driving force varying. By increasing the driving force, both crystals (in the steady-state) transform from a faceted polygon to an apex-bulged polygon, and then into a symmetric dendrite. For the faceted polygon, the interface advances by a layer-by-layer (LL) mode while for the apex-bulged polygonal and the dendritic crystals, it first adopts the LL mode and then transits into the multi-layer (ML) mode in the later stage. In particular, a shift of the nucleation sites from the face center to the area around the crystal tips is detected in the early growth stage of both crystals and is rationalized in terms of the relation between the crystal size and the driving force distribution. Finally, a parameter characterizing the complex shape change of square crystal is introduced. (paper)

  1. Principles of crystallization, and methods of single crystal growth

    International Nuclear Information System (INIS)

    Chacra, T.

    2010-01-01

    Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

  2. Persistência de canal arterial e comunicação interventricular em recém-nascida a termo filha de pais testemunha de Jeová

    Directory of Open Access Journals (Sweden)

    Robson Luis de Andrade Filho

    2015-10-01

    Full Text Available Introdução: A Declaração Universal dos Direitos do Homem, no inciso XVII, afirma que todo homem tem direito à liberdade de pensamento, consciência e religião; este direito inclui a liberdade de manifestar essa religião ou crença pelo ensino, pela prática, pelo culto e pela observância, isolada ou coletivamente, em público ou em particular. Diante disso, o objetivo é relatar o impasse médico diante do caso de uma paciente a termo de três meses de idade, portadora de canal arterial permanente e comunicação interventricular, cujos pais que professam a religião das testemunhas de Jeová, não autorizam a realização de cirurgia devido à necessidade do uso de componentes sanguíneos. Método: as informações foram obtidas mediante revisão de prontuário, entrevista com o médico responsável pelo caso e levantamento para estudo de literatura específica. Considerações finais e relevância: o caso relatado e o estudo das referências ressaltam que diante das condições previamente esclarecidas do paciente, a melhor intervenção possível é cirúrgica devido à persistência da condição, não sendo, porém permitida, devido a não aprovação por parte dos pais da criança. Evidencia-se assim, que a recusa ao recebimento de sangue total ou de seus componentes possui importante repercussão na esfera médica – acarretando dilemas éticos pois os médicos são instruídos a cuidar da manutenção da vida, porém no âmbito jurídico, se debate se é direito do paciente recusar um tratamento médico por objeção de consciência quando este, possivelmente, é o melhor a fim de preservar a vida do paciente.

  3. Comportamento mecânico e termo-mecânico de blendas poliméricas PBT/ABS Mechanical and thermo-mechanical behavior of PBT/ABS polymer blends

    Directory of Open Access Journals (Sweden)

    Luís Antonio S. Ferreira

    1997-03-01

    Full Text Available RESUMO: Blendas de poli(tereftalato de butileno (PBT e copolímero ABS foram estudadas usando-se três tipos diferentes de ABS. As blendas foram caracterizadas mecanicamente através de ensaios de tração e de impacto, e termo-mecanicamente através da determinação da temperatura de deflexão térmica (HDT. Uma influência mais pronunciada foi observada para a variação da composição química do ABS, em relação às diferentes composições de fase, onde blendas com ABS de maior proporção de acrilonitrila mostraram melhor comportamento. Foi observado que baixos níveis de ABS nas blendas proporcionam principalmente um aumento pronunciado da HDT e sem variação da resistência ao impacto, em relação ao PBT puro. Por outro lado, baixos níveis de PBT nas blendas não alteram as propriedades em relação ao ABS puro, com exceção da resistência ao impacto, que mostrou uma redução significativa.ABSTRACT: Polymer blends of poly(butylene terephthalate, PBT, and three grades of Acrylonitrile-Butadiene-Styrene copolymer, ABS, were studied. Polymer blends were characterized by impact resistance, tensile strength and heat deflection temperature tests. It was observed a stronger influence of the chemical composition of the ABS resin on the blends properties, mainly for the blends with higher ABS content which show better properties, than the phase composition of the ABS. It was observed that low levels of ABS in the blends promote mainly a high increase in HDT at the same level of impact resistance, as compared to neat PBT. On the other hand, low levels of PBT in the blend basically keep all the properties at the same level except the impact resistance which shows a significant decrease.

  4. Caracterização da imunogenicidade das proteínas recombinantes Virb9, Virb10 e fator termo instável de Elongação de Peptídeos de Anaplasma marginale em camundongos

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Canevari Castelão

    2012-10-01

    Full Text Available Considerando as limitações dos atuais métodos de controle contra a anaplasmose bovina, o desenvolvimento de uma vacina efetiva se faz necessário. A partir do advento da análise genômica e proteômica, novas proteínas de membrana de Anaplasma marginale foram identificadas como possíveis candidatas a componentes de uma vacina, tais como, VirB9,VirB10 e Fator Termo Instavél de Elongação de Peptídeos (EF-Tu. Embora estas proteínas ainda não estejam bem caracterizadas na membrana de A. marginale, a produção destas na forma recombinante (rVirB 9, rVirB10 e rEF-Tutem sido realizada, mas as mesmas ainda não foram exploradas em formulações vacinais. Neste trabalho, avaliou-se ouso de rVirB9, rVirB10 e rEF-Tu emulsionadas em adjuvante Montanide em camundongos. Nas condições testadas, verificou-se a indução de forte resposta imune humoral com a produção de IgG1 e IgG2a, sendo que as proporções dos níveis de produção destas subclasses indicam predomínio de IgG1. Entretanto, esplenócitos de animais, que foram injetados com rVirB9 ou rVirB10, produziram interferon-gama acima do limite de detecção do ensaio após estimulação in vitro, sinalizando assim resposta celular específica. Assim, novas avaliações serão realizadas com a finalidade de modular o perfil de resposta imune obtido em bovinos e avaliar a proteção contra A. marginale.

  5. Crystal structure and magnetic susceptibility of UOSe single crystals

    International Nuclear Information System (INIS)

    Kaczorowski, D.; Muenster Univ.; Poettgen, R.; Jeitschko, W.; Gajek, Z.; Zygmunt, A.

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T N =100±2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author)

  6. Crystal structure and magnetic susceptibility of UOSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaczorowski, D. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Poettgen, R.; Jeitschko, W. (Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Gajek, Z.; Zygmunt, A. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research)

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T[sub N]=100[+-]2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author).

  7. Crystallized Schroedinger cat states

    International Nuclear Information System (INIS)

    Castanos, O.; Lopez-Pena, R.; Man'ko, V.I.

    1995-01-01

    Crystallized Schroedinger cat states (male and female) are introduced on the base of extension of group construction for the even and odd coherent states of the electromagnetic field oscillator. The Wigner and Q functions are calculated and some are plotted for C 2 , C 3 , C 4 , C 5 , C 3v Schroedinger cat states. Quadrature means and dispersions for these states are calculated and squeezing and correlation phenomena are studied. Photon distribution functions for these states are given explicitly and are plotted for several examples. A strong oscillatory behavior of the photon distribution function for some field amplitudes is found in the new type of states

  8. Crystal structure of cafenstrole

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound (systematic name: N,N-diethyl-3-mesitylsulfonyl-1H-1,2,4-triazole-1-carboxamide, C16H22N4O3S, is a triazole herbicide. The dihedral angle between the planes of the triazole and benzene ring planes is 88.14 (10°. In the crystal, C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming one-dimensional chains along the a axis.

  9. Liquid Crystal Airborne Display

    Science.gov (United States)

    1977-08-01

    Cum.nings, J. P., et al., Properties and Limitations oe Liquid Crystals for Aircraft Displays, Honeywell Corporate Researc ."I Center, Final Report HR-72...basic module could be used to build displays for both the commercial and military! 157- marhecs, and so would establi sh a broad and sizable market ... market for the display becomes a reality; therein lies, f TABLE 16 THE COURSE OF FUTURE DISPLAY DEVELOPMENT Today 1976-77 1980 1985 Display Size 2" 1 3.2

  10. Crystal structure of pseudoguainolide

    Directory of Open Access Journals (Sweden)

    Noureddine Beghidja

    2015-03-01

    Full Text Available The lactone ring in the title molecule, C15H22O3 (systematic name: 3,4a,8-trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione, assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methylene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific interactions are noted in the the crystal packing.

  11. Radiation Damage in Scintillating Crystals

    CERN Document Server

    Zhu Ren Yuan

    1998-01-01

    Crystal Calorimetry in future high energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals, and concludes that the predominant radiation damage effect in crystal scintillators is the radiation induced absorption, or color center formation, not the loss of the scintillation light yield. The importance of maintaining crystal's light response uniformity and the feasibility to build a precision crystal calorimeter under radiation are elaborated. The mechanism of the radiation damage in scintillating crystals is also discussed. While the damage in alkali halides is found to be caused by the oxygen or hydroxyl contamination, it is the structure defects, such as oxygen vacancies, cause damage in oxides. Material analysis methods used to reach these conclusions are presented in details.

  12. Hopper Growth of Salt Crystals.

    Science.gov (United States)

    Desarnaud, Julie; Derluyn, Hannelore; Carmeliet, Jan; Bonn, Daniel; Shahidzadeh, Noushine

    2018-06-07

    The growth of hopper crystals is observed for many substances, but the mechanism of their formation remains ill understood. Here we investigate their growth by performing evaporation experiments on small volumes of salt solutions. We show that sodium chloride crystals that grow very fast from a highly supersaturated solution form a peculiar form of hopper crystal consisting of a series of connected miniature versions of the original cubic crystal. The transition between cubic and such hopper growth happens at a well-defined supersaturation where the growth rate of the cubic crystal reaches a maximum (∼6.5 ± 1.8 μm/s). Above this threshold, the growth rate varies as the third power of supersaturation, showing that a new mechanism, controlled by the maximum speed of surface integration of new molecules, induces the hopper growth of cubic crystals in cascade.

  13. Quasimetallic silicon micromachined photonic crystals

    International Nuclear Information System (INIS)

    Temelkuran, B.; Bayindir, Mehmet; Ozbay, E.; Kavanaugh, J. P.; Sigalas, M. M.; Tuttle, G.

    2001-01-01

    We report on fabrication of a layer-by-layer photonic crystal using highly doped silicon wafers processed by semiconductor micromachining techniques. The crystals, built using (100) silicon wafers, resulted in an upper stop band edge at 100 GHz. The transmission and defect characteristics of these structures were found to be analogous to metallic photonic crystals. We also investigated the effect of doping concentration on the defect characteristics. The experimental results agree well with predictions of the transfer matrix method simulations

  14. Termo de consentimento informado: a visão dos advogados e tribunais Término de consentimiento informado: la visión de los abogados y tribunales Informed consent: the understanding of lawyers and courts

    Directory of Open Access Journals (Sweden)

    Adriano Marteleto Godinho

    2010-04-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: Nos últimos anos, houve no Brasil um aumento do número de ações judiciais em função de erros médicos, devido, sobretudo, a uma conscientização cada vez maior da população em busca de qualidade no atendimento que lhe é oferecido. De acordo com a Constituição da República de 1988 e o Código de Defesa do Consumidor, o médico não pode submeter o seu paciente a tratamento ou procedimento terapêutico sem antes obter seu consentimento. O objetivo deste artigo foi conferir aos profissionais da medicina uma visão jurídica acerca do universo do consentimento informado. CONTEÚDO: O texto aborda o histórico, conceitos e fundamentos do Termo de Consentimento, requisitos para validade, a saber: capacidade do paciente, voluntariedade, compreensão e prestação das informações relevantes, assim como circunstâncias que dispensam o consentimento. CONCLUSÕES: Por meio da assinatura do Termo de Consentimento Informado o paciente declara estar ciente da natureza da intervenção médica e dos correspondentes riscos, assumindo-os livremente. Espera-se com este artigo tornar a classe médica mais consciente dos aspectos legais que giram em torno do tema, para que, a partir daí, sejam evitados os equívocos que costumeiramente transferem a sagrada relação médico-paciente dos consultórios e hospitais para os fóruns e tribunais.JUSTIFICATIVA Y OBJETIVOS: En los últimos años, se dio en Brasil un aumento del número de demandas judiciales en función de los errores médicos, principalmente, a causa de una concientización cada vez más fuerte de la población que busca la calidad en la atención que le ofrecen. De acuerdo con la Constitución de la República de 1988 y el Código de la Defensa del Consumidor, el médico no puede someter a su paciente a un tratamiento o procedimiento terapéutico sin que antes tenga su autorización. El objetivo de este artículo fue darles a los profesionales de la medicina una

  15. Variabilidade da frequência cardíaca em neonatos prematuros e de termo Variabilidad de la frecuencia cardíaca en neonatos prematuros y de término Heart rate variability in preterm and term neonates

    Directory of Open Access Journals (Sweden)

    Fabio Augusto Selig

    2011-06-01

    Full Text Available FUNDAMENTO: Várias publicações têm demonstrado a importância do sistema nervoso autônomo por meio dos componentes simpático e parassimpático na gerência da interação entre as diferentes partes do organismo humano. Esses estudos aplicaram técnicas lineares e não lineares (Teoria do Caos de avaliação em diferentes situações, doenças e faixas etárias, tendo como ferramenta a variabilidade da frequência cardíaca (VFC. OBJETIVO: Aplicar os conhecimentos das dinâmicas linear e não linear na avaliação de neonatos prematuros (NPT, analisando sua VFC e comparando com neonatos de termo (NT saudáveis. MÉTODOS: Quarenta e oito neonatos prematuros com diferentes idades gestacionais tiveram seus batimentos cardíacos captados com auxílio do equipamento Polar Advanced S810i e sua VFC obtida pelo registro dos intervalos RR. A VFC foi analisada nos domínios do tempo (SDNN, RMSSD, SD1/SD2, da frequência (VLF, LF, HF e a relação LF/HF e do caos (TAU e sua normalização [TAU(n], Expoente de Lyapunov e Entropia. Os NPT foram comparados com um grupo de 78 NT saudáveis e sem intercorrências perinatais com auxílio do teste não paramétrico de Kruskal-Wallis. RESULTADOS: Detectou-se diferença estatisticamente significante entre os grupos para todas as variáveis estudadas, tanto no domínio do tempo como nos da frequência e do caos. CONCLUSÃO: Neonatos prematuros exibem comportamento menos complexo da variabilidade da frequência cardíaca que neonatos de termo, fato comprovado nos domínios do tempo, da frequência e do caos. O estudo da variabilidade cardíaca nesse grupo pode ser considerado uma ferramenta a mais na avaliação da maturação autonômica e, consequentemente, da progressão para eutrofia.FUNDAMENTO: Varias publicaciones han demostrado la importancia del sistema nervioso autónomo por medio de los componentes simpático y parasimpático en el manejo de la interacción entre las diferentes partes del organismo

  16. Baixas doses de misoprostol vaginal (12,5 versus 25 mcg para indução do parto a termo Low-dose vaginal misoprostol (12.5 versus 25 µg for induction of labor at term

    Directory of Open Access Journals (Sweden)

    Francisco Airton Rangel Filho

    2007-12-01

    Full Text Available OBJETIVO: comparar a efetividade de baixas doses de misoprostol vaginal (12,5 versus 25 mcg para indução do trabalho de parto. MÉTODOS: ensaio clínico controlado, randomizado, duplo-cego, realizado entre maio de 2005 e abril de 2006. Foram incluídas 62 gestantes com gravidez a termo, membranas íntegras, que necessitaram de indução do parto. Foi administrado 25 mcg (32 ou 12,5 mcg de misoprostol (30, a cada quatro horas, até, no máximo, oito doses. Estudaram-se o tipo de parto, tempo entre o início da indução e o parto, complicações perinatais e efeitos maternos adversos. As variáveis de controle foram idades materna e gestacional, paridade e índice de Bishop. Os testes estatísticos utilizados foram cálculos de médias, desvios padrão e teste t de Student (variáveis numéricas contínuas, c² (variáveis categóricas e Mann-Whitney (variáveis discretas. RESULTADOS: não houve diferença significante entre o Grupo de 12,5 e 25 mcg em relação ao intervalo de tempo entre a primeira dose e o parto (1.524 minutos versus 1.212 minutos, p=0,3, na freqüência de partos vaginais (70 versus 71,8%, p=0,7, no escore de Apgar inferior a sete ao quinto minuto (3,3 versus 6,25%, p=0,5 e na freqüência de taquissistolia (3,3 versus 6,2%, p=0,5. A média da dose total administrada de misoprostol foi significativamente maior no Grupo de 25 mcg (40 versus 61,2 mcg, p=0,03. CONCLUSÕES: misoprostol vaginal na dose de 12,5 mcg foi eficiente, com efeitos colaterais semelhante, à dose de 25 mcg de misoprostol vaginal, para indução do parto a termo.PURPOSE: to compare the effectiveness of low doses of vaginal misoprostol (12.5 versus 25 µg for induction of labor. METHODS: a double-blind, randomized, controlled clinical trial was performed in Santa Casa de Misericórdia de Sobral, from May 2005 to April 2006. Sixty-two term pregnant women, with intact membranes and with indication for labor induction, were included. They randomly received 25

  17. Prevalência e fatores de risco para a retinopatia da prematuridade: estudo com 450 pré-termos de muito baixo peso Prevalence and risk factors for retinopathy of prematurity: study with 450 very low birth weight preterm infants

    Directory of Open Access Journals (Sweden)

    João Borges Fortes Filho

    2009-02-01

    Full Text Available OBJETIVO:Analisar prevalência e fatores de risco para a retinopatia da prematuridade (ROP entre pré-termos com peso de nascimento (PN d"1.500 gramas e/ou idade gestacional (IG d"32 semanas admitidos em uma instituição hospitalar universitária de nível terciário. MÉTODOS: Estudo de coorte institucional, prospectivo e descritivo, realizado entre outubro de 2002 e julho de 2008, incluindo todos os pré-termos com PN d"1.500 gramas e/ou com IG d"32 semanas, que sobreviveram até a 42ª semana de IG corrigida. Foram determinadas a prevalência da ROP em seus vários estadiamentos evolutivos. Os principais fatores de risco para o surgimento da ROP no período pós-natal foram comparados por análises uni e multivariadas entre os pacientes que desenvolveram e os que não desenvolveram a doença. Para a análise das variáveis contínuas entre os dois grupos, foi usado o Teste t (Student para amostras independentes e para a comparação das variáveis categóricas, o Qui-Quadrado. A regressão logística incluiu as variáveis com significância após a análise univariada. RESULTADOS:Foram estudadas 450 crianças cuja média de PN e IG foram 1.213,50 gramas (± 277,4 e 30,3 semanas (± 2,2, respectivamente. A ROP, em qualquer estadiamento, afetou 24,2% das crianças. Doença limiar, necessitando de tratamento pela fotocoagulação, ocorreu em 24 pacientes (5,3%. Após análise univariada, a IG, o PN, o ganho ponderal do nascimento até a 6ª semana de vida, o uso de oxigenioterapia em ventilação mecânica e de indometacina, as ocorrências de sepse e hemorragia intraventricular e a necessidade de transfusões sanguíneas, estiveram associados com a ROP. A regressão logística confirmou a importância da IG (OR: 0,856; IC95%: 1,141-1,447; P=0,014, do baixo ganho ponderal (OR: 0,997; IC95%: 0,996-0,999; PPURPOSE: This study aims to analyze prevalence and risk factors for retinopathy of prematurity (ROP among preterms with birth weight (BW d"1

  18. Cuidado ao desenvolvimento: intervenções de proteção ao desenvolvimento inicial de recém-nascidos pré-termo Developmental care: protection approach for early development of preterm infants

    Directory of Open Access Journals (Sweden)

    Cláudia Maria Gaspardo

    2010-03-01

    Full Text Available OBJETIVO: Revisar ensaios clínicos randomizados, publicados entre 2002 e 2009, sobre a eficácia de intervenções em Cuidado ao Desenvolvimento em recém-nascidos pré-termo em Unidade de Terapia Intensiva Neonatal. FONTES DE DADOS: Foram selecionados estudos randomizados dos bancos de dados Medline, PsycINFO, ISI Web of Science, LILACS e SciELO, usando-se as palavras-chave "developmental care" e "neonate". Realizou-se uma análise metodológica dos estudos, com base nos critérios: randomização, estimativa do tamanho amostral, perda amostral, critérios de inclusão e exclusão, controle de variáveis de confusão, validade dos instrumentos, condição "cega" do pesquisador, realização de seguimento, validades externa e ecológica e cuidados éticos. SÍNTESE DOS DADOS: As intervenções em Cuidado ao Desenvolvimento promoveram melhora em curto prazo nos resultados fisiológicos, comportamentais, neurológicos e clínicos dos recém-nascidos. Observou-se diminuição da reatividade à dor nos recém-nascidos durante procedimentos de pesagem e troca de fraldas. Os pais que receberam intervenções em Cuidado ao Desenvolvimento passaram a apresentar maior senso de competência para cuidar do recém-nascido. Os profissionais treinados em Cuidado ao Desenvolvimento demonstraram melhor desempenho na assistência ao recém-nascido e valorizaram mais os estímulos ambientais, físicos e sociais. CONCLUSÕES: Intervenções em Cuidado ao Desenvolvimento na Unidade de Terapia Intensiva Neonatal promoveram benefícios ao desenvolvimento e saúde dos recém-nascidos pré-termo no período neonatal e no primeiro ano de vida. Em estudos futuros, recomenda-se maior rigor metodológico no que se refere à condição de pesquisador "cego" em relação às intervenções e controle das variáveis de confusão. Estudos prospectivo-longitudinais são necessários para avaliar a eficácia das intervenções em médio e longo prazo no desenvolvimento

  19. Aluminum-air battery crystallizer

    Science.gov (United States)

    Maimoni, A.

    1987-01-01

    A prototype crystallizer system for the aluminum-air battery operated reliably through simulated startup and shutdown cycles and met its design objectives. The crystallizer system allows for crystallization and removal of the aluminium hydroxide reaction product; it is required to allow steady-state and long-term operation of the aluminum-air battery. The system has to minimize volume and maintain low turbulence and shear to minimize secondary nucleation and energy consumption while enhancing agglomeration. A lamella crystallizer satisfies system constraints.

  20. Physical Properties of Liquid Crystals

    CERN Document Server

    Gray, George W; Spiess, Hans W

    1999-01-01

    This handbook is a unique compendium of knowledge on all aspects of the physics of liquid crystals. In over 500 pages it provides detailed information on the physical properties of liquid crystals as well as the recent theories and results on phase transitions, defects and textures of different types of liquid crystals. An in-depth understanding of the physical fundamentals is a prerequisite for everyone working in the field of liquid crystal research. With this book the experts as well as graduate students entering the field get all the information they need.

  1. Wetting of cholesteric liquid crystals.

    Science.gov (United States)

    Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

    2016-02-01

    We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal.

  2. Preventing Crystal Agglomeration of Pharmaceutical Crystals Using Temperature Cycling and a Novel Membrane Crystallization Procedure for Seed Crystal Generation

    Directory of Open Access Journals (Sweden)

    Elena Simone

    2018-01-01

    Full Text Available In this work, a novel membrane crystallization system was used to crystallize micro-sized seeds of piroxicam monohydrate by reverse antisolvent addition. Membrane crystallization seeds were compared with seeds produced by conventional antisolvent addition and polymorphic transformation of a fine powdered sample of piroxicam form I in water. The membrane crystallization process allowed for a consistent production of pure monohydrate crystals with narrow size distribution and without significant agglomeration. The seeds were grown in 350 g of 20:80 w/w acetone-water mixture. Different seeding loads were tested and temperature cycling was applied in order to avoid agglomeration of the growing crystals during the process. Focused beam reflectance measurement (FBRM; and particle vision and measurement (PVM were used to monitor crystal growth; nucleation and agglomeration during the seeded experiments. Furthermore; Raman spectroscopy was used to monitor solute concentration and estimate the overall yield of the process. Membrane crystallization was proved to be the most convenient and consistent method to produce seeds of highly agglomerating compounds; which can be grown via cooling crystallization and temperature cycling.

  3. Inelastic light scattering in crystals

    Science.gov (United States)

    Sushchinskii, M. M.

    The papers presented in this volume are concerned with a variety of problems in optics and solid state physics, such as Raman scattering of light in crystals and disperse media, Rayleigh and inelastic scattering during phase transitions, characteristics of ferroelectrics in relation to the general soft mode concept, and inelastic spectral opalescence. A group-theory approach is used to classify the vibrational spectra of the crystal lattice and to analyze the properties of idealized crystal models. Particular attention is given to surface vibrational states and to the study of the surface layers of crystals and films by light scattering methods.

  4. Tunable Topological Phononic Crystals

    KAUST Repository

    Chen, Zeguo; Wu, Ying

    2016-01-01

    Topological insulators first observed in electronic systems have inspired many analogues in photonic and phononic crystals in which remarkable one-way propagation edge states are supported by topologically nontrivial band gaps. Such band gaps can be achieved by breaking the time-reversal symmetry to lift the degeneracy associated with Dirac cones at the corners of the Brillouin zone. Here, we report on our construction of a phononic crystal exhibiting a Dirac-like cone in the Brillouin zone center. We demonstrate that simultaneously breaking the time-reversal symmetry and altering the geometric size of the unit cell result in a topological transition that we verify by the Chern number calculation and edge-mode analysis. We develop a complete model based on the tight binding to uncover the physical mechanisms of the topological transition. Both the model and numerical simulations show that the topology of the band gap is tunable by varying both the velocity field and the geometric size; such tunability may dramatically enrich the design and use of acoustic topological insulators.

  5. Crystal growth and doping

    International Nuclear Information System (INIS)

    Paorici, C.

    1980-01-01

    Section 1 contains a self-consistent review of the basic growth features. After a short introduction concerning the driving force acting in a crystallization process, three main topics are broadly discussed: (i) interface kinetics; (ii) transport kinetics, and (iii) growth stability conditions. On point (i), after definition of the nature of interface, using Temkin's model, the growth mechanisms predicted by Burton, Cabrera and Frank (BCF) and bidimensional nucleation theories are fully developed. On points (ii) and (iii), the differential equations of the constitutional (concentration) and thermal fields are presented and discussed in terms of relevant approximations, suitable boundary conditions and limit values expected in order to have growth stability. Section 2 reports various experimental procedures for growing bulk crystals from the melt, from solutions and from the vapour phase. The basic concepts of Section 1 are amply employed for a critical discussion of possibilities, advantages and drawbacks of the methods described. Along the same lines, in Section 3 the principal epitaxial deposition procedures are highlighted. Section 4 contains a brief account of doping and of stoichiometry-defect control procedures. There is a long, carefully chosen list of bibliographical references. (author)

  6. Liquid Crystals in Tribology

    Directory of Open Access Journals (Sweden)

    María-Dolores Bermúdez

    2009-09-01

    Full Text Available Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs, only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs. Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.

  7. Tunable Topological Phononic Crystals

    KAUST Repository

    Chen, Zeguo

    2016-05-27

    Topological insulators first observed in electronic systems have inspired many analogues in photonic and phononic crystals in which remarkable one-way propagation edge states are supported by topologically nontrivial band gaps. Such band gaps can be achieved by breaking the time-reversal symmetry to lift the degeneracy associated with Dirac cones at the corners of the Brillouin zone. Here, we report on our construction of a phononic crystal exhibiting a Dirac-like cone in the Brillouin zone center. We demonstrate that simultaneously breaking the time-reversal symmetry and altering the geometric size of the unit cell result in a topological transition that we verify by the Chern number calculation and edge-mode analysis. We develop a complete model based on the tight binding to uncover the physical mechanisms of the topological transition. Both the model and numerical simulations show that the topology of the band gap is tunable by varying both the velocity field and the geometric size; such tunability may dramatically enrich the design and use of acoustic topological insulators.

  8. Crystal Compton Camera

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, Klaus-Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Braverman, Joshua B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Harrison, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hornback, Donald Eric [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fabris, Lorenzo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Newby, Jason [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2013-09-26

    Stand-off detection is one of the most important radiation detection capabilities for arms control and the control of illicit nuclear materials. For long range passive detection one requires a large detector and a means of “seeing through” the naturally occurring and varying background radiation, i.e. imaging. Arguably, Compton imaging is the best approach over much of the emission band suitable for long range detection. It provides not only imaging, but more information about the direction of incidence of each detected gamma-ray than the alternate approach of coded-aperture imaging. The directional information allows one to reduce the background and hence improve the sensitivity of a measurement. However, to make an efficient Compton imager requires localizing and measuring the simultaneous energy depositions when gamma-rays Compton scatter and are subsequently captured within a single, large detector volume. This concept has been demonstrated in semi-conductor detectors (HPGe, CZT, Si) but at ~ $1k/cm3 these materials are too expensive to build the large systems needed for standoff detection. Scintillator detectors, such as NaI(Tl), are two orders of magnitude less expensive and possess the energy resolution required to make such an imager. However, they do not currently have the ability to localize closely spaced, simultaneous energy depositions in a single large crystal. In this project we are applying a new technique that should, for the first time ever, allow cubic-millimeter event localization in a bulk scintillator crystal.

  9. Electron spectroscopy of crystals

    CERN Document Server

    Nemoshkalenko, V V

    1979-01-01

    This book is conceived as a monograph, and represents an up-to-date collection of information concerning the use of the method of X-ray photoelectron spec­ troscopy in the study of the electron structure of crystals, as well as a personal interpretation of the subject by the authors. In a natural way, the book starts in Chapter 1 with a recapitulation of the fundamentals of the method, basic relations, principles of operation, and a com­ parative presentation of the characteristics and performances of the most com­ monly used ESCA instruments (from the classical ones-Varian, McPherson, Hewlett Packard, and IEEE-up to the latest model developed by Professor Siegbahn in Uppsala), and continues with a discussion of some of the difficult problems the experimentalist must face such as calibration of spectra, prepara­ tion of samples, and evaluation of the escape depth of electrons. The second chapter is devoted to the theory of photoemission from crystal­ line solids. A discussion of the methods of Hartree-Fo...

  10. Reconfigurable topological photonic crystal

    Science.gov (United States)

    Shalaev, Mikhail I.; Desnavi, Sameerah; Walasik, Wiktor; Litchinitser, Natalia M.

    2018-02-01

    Topological insulators are materials that conduct on the surface and insulate in their interior due to non-trivial topology of the band structure. The edge states on the interface between topological (non-trivial) and conventional (trivial) insulators are topologically protected from scattering due to structural defects and disorders. Recently, it was shown that photonic crystals (PCs) can serve as a platform for realizing a scatter-free propagation of light waves. In conventional PCs, imperfections, structural disorders, and surface roughness lead to significant losses. The breakthrough in overcoming these problems is likely to come from the synergy of the topological PCs and silicon-based photonics technology that enables high integration density, lossless propagation, and immunity to fabrication imperfections. For many applications, reconfigurability and capability to control the propagation of these non-trivial photonic edge states is essential. One way to facilitate such dynamic control is to use liquid crystals (LCs), which allow to modify the refractive index with external electric field. Here, we demonstrate dynamic control of topological edge states by modifying the refractive index of a LC background medium. Background index is changed depending on the orientation of a LC, while preserving the topology of the system. This results in a change of the spectral position of the photonic bandgap and the topological edge states. The proposed concept might be implemented using conventional semiconductor technology, and can be used for robust energy transport in integrated photonic devices, all-optical circuity, and optical communication systems.

  11. Optics of globular photonic crystals

    International Nuclear Information System (INIS)

    Gorelik, V S

    2007-01-01

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter ∼200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  12. Amine free crystal structure: The crystal structure of d(CGCGCG)2 and methylamine complex crystal

    International Nuclear Information System (INIS)

    Ohishi, Hirofumi; Tsukamoto, Koji; Hiyama, Yoichi; Maezaki, Naoyoshi; Tanaka, Tetsuaki; Ishida, Toshimasa

    2006-01-01

    We succeeded in the crystallization of d(CGCGCG) 2 and methylamine Complex. The crystal was clear and of sufficient size to collect the X-ray crystallographic data up to 1.0 A resolution using synchrotron radiation. As a result of X-ray crystallographic analysis of 2F o - F c map was much clear and easily traced. It is First time monoamine co-crystallizes with d(CGCGCG) 2 . However, methylamine was not found from the complex crystal of d(CGCGCG) 2 and methylamine. Five Mg ions were found around d(CGCGCG) 2 molecules. These Mg ions neutralized the anion of 10 values of the phosphate group of DNA with five Mg 2+ . DNA stabilized only by a metallic ion and there is no example of analyzing the X-ray crystal structure like this. Mg ion stabilizes the conformation of Z-DNA. To use monoamine for crystallization of DNA, we found that we can get only d(CGCGCG) 2 and Mg cation crystal. Only Mg cation can stabilize the conformation of Z-DNA. The method of using the monoamine for the crystallization of DNA can be applied to the crystallization of DNA of long chain of length in the future like this

  13. The Morse code effect: A crystal-crystal transformation observed in gel-grown lead (II) oxalate crystals

    Science.gov (United States)

    Lisgarten, J. N.; Marks, J. A.

    2018-05-01

    This paper reports on an unusual crystal-crystal transformation phenomenon, which we have called the Morse Code Effect, based on the change in appearance of lead(II) oxalate crystals grown in agarose gels.

  14. Growing Crystals on the Ceiling.

    Science.gov (United States)

    Christman, Robert A.

    1980-01-01

    Described is a method of studying growing crystals in a classroom utilizing a carrousel projector standing vertically. A saturated salt solution is placed on a slide on the lens of the projector and the heat from the projector causes the water to evaporate and salt to crystalize. (Author/DS)

  15. Photonic-crystal fibers gyroscope

    Directory of Open Access Journals (Sweden)

    Ali Muse Haider

    2015-01-01

    Full Text Available In this paper we proposed to use of a photonic crystal fiber with an inner hollow defect. The use of such fibers is not affected by a material medium on the propagation of optical radiation. Photonic crystal fibers present special properties and capabilities that lead to an outstanding potential for sensing applications

  16. Dipole plasma in molecular crystals

    International Nuclear Information System (INIS)

    Kotel'nikov, Yu.E.; Kochelaev, B.I.

    1976-01-01

    Collective oscillations in a system of electric dipoles of molecular crystals are investigated. It has been proved in the exciton approximation that in an elementary cell of a molecular crystal with one molecule there may exist energy fluctuations of the ''dipole'' plasma, analogous to plasma oscillations in the charged Fermi liquid

  17. Diffraction. Single crystal, magnetic

    International Nuclear Information System (INIS)

    Heger, G.

    1999-01-01

    The analysis of crystal structure and magnetic ordering is usually based on diffraction phenomena caused by the interaction of matter with X-rays, neutrons, or electrons. Complementary information is achieved due to the different character of X-rays, neutrons and electrons, and hence their different interactions with matter and further practical aspects. X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (K.A.)

  18. Raman study of ? crystals

    Science.gov (United States)

    Pimenta, M. A.; Oliveira, M. A. S.; Bourson, P.; Crettez, J. M.

    1997-09-01

    In this work we present a polarized Raman study of 0953-8984/9/37/020/img7 single crystals for several values of the concentration 0953-8984/9/37/020/img8 made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range 0953-8984/9/37/020/img9. In each of the spectra we found two bands at about 590 and 0953-8984/9/37/020/img10, probably associated with the existence of 0953-8984/9/37/020/img11 structures in the solid solutions.

  19. Taub-Nut Crystal

    Science.gov (United States)

    Imazato, Harunobu; Mizoguchi, Shun'ya; Yata, Masaya

    We consider the Gibbons-Hawking metric for a three-dimensional periodic array of multi-Taub-NUT centers, containing not only centers with a positive NUT charge but also ones with a negative NUT charge. The latter are regarded as representing the asymptotic form of the Atiyah-Hitchin metric. The periodic arrays of Taub-NUT centers have close parallels with ionic crystals, where the Gibbons-Hawking potential plays the role of the Coulomb static potential of the ions, and are similarly classified according to their space groups. After a periodic identification and a Z2 projection, the array is transformed by T-duality to a system of NS5-branes with the SU(2) structure, and a further standard embedding yields, though singular, a half-BPS heterotic 5-brane background with warped compact transverse dimensions. A discussion is given on the possibility of probing the singular geometry by two-dimensional gauge theories.

  20. Natural photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vigneron, Jean Pol, E-mail: jean-pol.vigneron@fundp.ac.be [Research Center in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), rue de Bruxelles, 61, B-5000 Namur (Belgium); Simonis, Priscilla [Research Center in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), rue de Bruxelles, 61, B-5000 Namur (Belgium)

    2012-10-15

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  1. Crystal Ball at PEP

    International Nuclear Information System (INIS)

    Bartel, W.; Bulos, F.; Luke, D.; Peck, C.; Strauch, K.

    1975-01-01

    The modifications to the SPEAR version of the Crystal Ball required by the higher energies at PEP are discussed. Since the hadron multiplicity is expected to rise as log s, their average energy must rise. On the other hand, if the hadrons are produced in jets, the low energy part of their spectrum is not heavily depleted. This implies that modifications for high energy particles should not deteriorate low energy performance. An external iron calorimeter for measuring the high energy hadrons, charged and neutral, is considered. To improve the angular resolution on γ's, an active internal converter has been studied, estimates have been made of its expected performance, and difficulties requiring further study have been outlined

  2. Natural photonic crystals

    International Nuclear Information System (INIS)

    Vigneron, Jean Pol; Simonis, Priscilla

    2012-01-01

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  3. Modeling liquid crystal polymeric devices

    Science.gov (United States)

    Gimenez Pinto, Vianney Karina

    The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.

  4. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  5. General crystal in prebiotic context

    International Nuclear Information System (INIS)

    Simon, I.

    1993-09-01

    General crystal is an extension of the crystal concept to any form of matter which exhibit neighbour structure determination. This extension makes many results of solid state physics applicable to heterogeneous matter. Among other it includes the description of phase transition from random to unique structure. The advantage of the general crystal approach is demonstrated on globular protein, on of the most important macromolecules of life, which are capable to adopt unique 3D structure spontaneously, regardless of the heterogeneous character of their chemical structure and conformation. It is suggested that the use of general crystal concept may help to find candidates among heterogeneous matters capable to spontaneous self-organization in the same way as crystallization results in unique structure of homogeneous matter, and to apply some of the results of solid state physics to describe the phase transition and other behaviour of this matter. (author). 10 refs

  6. Bacterial Ice Crystal Controlling Proteins

    Science.gov (United States)

    Lorv, Janet S. H.; Rose, David R.; Glick, Bernard R.

    2014-01-01

    Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

  7. Crystallization of glycine with ultrasound

    DEFF Research Database (Denmark)

    Louhi-Kultanen, Marjatta; Karjalainen, Milja; Rantanen, Jukka

    2006-01-01

    Sonocrystallization has proved to be an efficient tool to influence the external appearance and structure of a crystalline product obtained by various crystallization methods. The present work focuses on high intensity sonocrystallization of glycine by varying amplitude of ultrasound with an ultr...... ultrasound power. This study also showed, the higher the ultrasound amplitude the smaller the crystals obtained.......Sonocrystallization has proved to be an efficient tool to influence the external appearance and structure of a crystalline product obtained by various crystallization methods. The present work focuses on high intensity sonocrystallization of glycine by varying amplitude of ultrasound...... with an ultrasound frequency of 20kHz at two temperature ranges 40-50 and 20-30 degrees C in a jacketed 250-ml cooling crystallizer equipped with a stirrer. The polymorph composition of the obtained crystals was analyzed with a temperature variable X-ray powder diffractometer (XRPD). XRPD results showed that...

  8. Springer Handbook of Crystal Growth

    CERN Document Server

    Dhanaraj, Govindhan; Prasad, Vishwanath; Dudley, Michael

    2010-01-01

    Over the years, many successful attempts have been made to describe the art and science of crystal growth. Most modern advances in semiconductor and optical devices would not have been possible without the development of many elemental, binary, ternary, and other compound crystals of varying properties and large sizes. The objective of the Springer Handbook of Crystal Growth is to present state-of-the-art knowledge of both bulk and thin-film crystal growth. The goal is to make readers understand the basics of the commonly employed growth processes, materials produced, and defects generated. Almost 100 leading scientists, researchers, and engineers from 22 different countries from academia and industry have been selected to write chapters on the topics of their expertise. They have written 52 chapters on the fundamentals of bulk crystal growth from the melt, solution, and vapor, epitaxial growth, modeling of growth processes and defects, techniques of defect characterization as well as some contemporary specia...

  9. Growth of emerald single crystals

    International Nuclear Information System (INIS)

    Bukin, G.V.; Godovikov, A.A.; Klyakin, V.A.; Sobolev, V.S.

    1986-01-01

    In addition to its use for jewelry, emerald can also be used in low-noise microwave amplifiers. The authors discuss flux crystallization of emerald and note that when emerald is grown by this method, it is desirable to use solvents which dissolve emerald with minimum deviations from congruence but at the same time with sufficient high efficiency. Emerald synthesis and crystal growth from slowly cooled solutions is discussed as another possibility. The techniques are examined. Vapor synthesis and growht of beryl crystals re reviewed and the authors experimentally study the seeded CVD crystallization of beryl from BeO, Al 2 O 3 and SiO 2 oxides, by using complex compounds as carrier agents. The color of crystals of emerald and other varieties of beryl is detemined by slelective light absorption in teh visible part of the spectrum and depends on the density and structural positions of chromphore ions: chromium, iron, vanadium, nickel, manganese and cobalt

  10. MyCrystals - a simple visual data management program for laboratory-scale crystallization experiments

    DEFF Research Database (Denmark)

    Løvgreen, Monika Nøhr; Løvgreen, Mikkel; Christensen, Hans Erik Mølager

    2009-01-01

    MyCrystals is designed as a user-friendly program to display crystal images and list crystallization conditions. The crystallization conditions entry fields can be customized to suit the experiments. MyCrystals is also able to sort the images by the entered crystallization conditions, which...

  11. Problemas oftalmológicos mais freqüentes e desenvolvimento visual do pré-termo extremo Frequent ophthalmologic problems and visual development of preterm newborn infants

    Directory of Open Access Journals (Sweden)

    Rosa Maria Graziano

    2005-03-01

    Full Text Available OBJETIVO: Revisar conceitos do desenvolvimento visual e principais alterações oculares do recém-nascido prematuro. Salientar a importância do exame oftalmológico preventivo e tratamento precoce das doenças oculares. FONTE DOS DADOS: Dados de literatura. SÍNTESE DE DADOS: A visão é um dos mais importantes sentidos no desenvolvimento físico e cognitivo normal da criança. Em recém-nascido prematuro, as funções visual, motora e cognitiva, quando comparadas às de crianças de termo em idade escolar, são prejudicadas. Isto se deve mais à imaturidade do sistema nervoso central do que a lesões localizadas em estruturas oculares e/ou corticais. A retinopatia da prematuridade, o estrabismo e os erros de refração são as principais alterações oftálmicas secundárias à prematuridade descritas na literatura. A retinopatia da prematuridade é uma das principais causas de cegueira prevenível na infância. Calcula-se que, em média, 562 crianças fiquem cegas por ano no Brasil, um custo socioeconômico alto, principalmente por se tratar de uma doença passível de tratamento. Muito pode ser feito pela criança com deficiência visual; programas de estimulação visual precoce permitem que a criança possa ter uma integração maior com seu meio. CONCLUSÕES: Recomenda-se que todo recém-nascido prematuro com p OBJECTIVES: To review the concepts of visual development and the major ocular abnormalities in preterm newborns. To emphasize the importance of preventive ophthalmologic examination and early treatment of ocular disorders. SOURCES OF DATA: A review of published data. SUMMARY OF FINDINGS: Vision is one of the most important senses in the normal physical and cognitive development of children. Schoolchildren who were born preterm have impaired visual, motor and cognitive functions when compared to those of children born full term. This is more a consequence of central nervous system immaturity than of localized injuries to ocular and

  12. Intervenção fonoaudiológica em recém-nascido pré-termo com gastrosquise Speech language therapy in a preterm newborn infant with gastroschisis

    Directory of Open Access Journals (Sweden)

    Marilene de Souza Rocha

    2007-03-01

    Full Text Available O objetivo deste estudo foi descrever a intervenção fonoaudiológica para a adequação da função alimentar por meio da avaliação e tratamento do sistema estomatognático e suas funções. O estudo foi feito a partir do relato de caso de um recém-nascido pré-termo com gastrosquise que foi alimentado por sonda, atendido na Neonatologia do Hospital Luterano, no período de 29/03/2005 a 22/04/2005. A avaliação fonoaudiológica foi realizada, seguindo o protocolo padronizado do serviço de Neonatologia e apresentou os seguintes resultados: órgãos do sistema estomatognático no que se refere à postura, conformação e mobilidade dentro da normalidade; reflexos orais presentes; força e ritmo adequados na sucção não nutritiva; alteração na sensibilidade oral com reflexo nauseoso anteriorizado e exacerbado; sinal de estresse de alteração respiratória durante a sucção nutritiva na mamadeira; e dificuldade de pegar o seio materno. Foram realizadas três sessões de intervenção fonoaudiológica, uma vez por semana, com orientação para a equipe de enfermagem dar continuidade na estimulação oral nos demais dias. Em uma das sessões, a mãe recebeu orientações sobre os benefícios da amamentação e a importância do uso adequado de chupetas e bico de mamadeira do tipo ortodôntico para o desenvolvimento adequado das funções orais. O recém-nascido do relato de caso teve alta sem alterações orais, mamando no seio materno com complementação de mamadeira, sugerindo desta forma, a importância da intervenção fonoaudiológica para a adequação da função alimentar.The aim of this study was to describe the speech-language therapy regarding the adequation of the feeding function by assessing and treating the stomatognathic system and its functions. The study was carried out based on a case report of a preterm newborn infant with gastroschisis, who was tube fed while assisted in the Neonatology division of Lutheran Hospital

  13. Exfoliated epithelial cells: potentials to explore gastrointestinal maturation of preterm infants Células epiteliais exfoliadas: potencial para investigar a maturação gastrointestinal em crianças pré-termo

    Directory of Open Access Journals (Sweden)

    Bertrand Kaeffer

    2010-03-01

    microscópico para demonstrar a presença de células típicas com medições sobre um número limitado de biomarcadores. Apenas uns poucos estudos usando proteômica ou transcriptômica estão disponíveis e discutem sobre referenciais de tecidos e normalização. A principal vantagem de medidas realizadas em células epiteliais exfoliadas é que elas são estritamente não invasivas e abertas à possibilidade de avaliar a maturação de tecidos gástricos e intestinais em experimentos de longo prazo feitos no mesmo animal ou em pesquisas translacionais com amostras obtidas de crianças pré-termo.

  14. Efeitos do Método Mãe Canguru nos sinais vitais de recém-nascidos pré-termo de baixo peso Effects of Kangaroo Mother Care on the vital signs of low-weight preterm newborns

    Directory of Open Access Journals (Sweden)

    CM Almeida

    2007-02-01

    Full Text Available OBJETIVO: Avaliar as freqüências cardíaca e respiratória, a pressão arterial média, a temperatura e a saturação periférica de oxigênio dos recém-nascidos pré-termo (RNPT de baixo peso, antes e após a aplicação do MMC. MÉTODOS: Foram avaliados 22 RNPT de baixo peso, saudáveis, de ambos os sexos, não portadores de deficiências neurológicas, cardíacas e/ou respiratórias. A avaliação foi realizada após trinta minutos de permanência do RNPT em berço comum e após trinta minutos de aplicação do MMC, por 3 dias consecutivos. Para a avaliação, foram utilizados monitor cardíaco com dispositivo para medida da pressão arterial média de forma não invasiva e sensor para a oximetria de pulso, termômetro e cronômetro. RESULTADOS: Os resultados não mostraram alterações significativas quanto à pressão arterial média (p> 0,05 e freqüência cardíaca (p> 0,05 após a aplicação do MMC, mas, por outro lado, houve aumento significativo da temperatura axilar (pOBJECTIVE: The aim of this study was to evaluate the heart and respiration rates, mean arterial pressure, temperature and peripheral oxygen saturation of low-weight preterm newborns, before and after the application of kangaroo mother care. METHOD: Twenty-two healthy low-weight preterm newborns of both sexes were studied. None of them had neurological, cardiac and/or respiratory deficiencies. Assessments were made after the newborn had been left in an ordinary cot for 30 minutes and after 30 minutes of kangaroo mother care, on three consecutive days. For these evaluations, a heart monitor with a device for non-invasively measuring mean arterial pressure, a sensor for pulse oximetry, a thermometer and a chronometer were utilized. RESULTS: There were no significant changes in mean arterial pressure (p> 0.05 or heart rate (p> 0.05 after applying kangaroo mother care. However, there were significant increases in axillary temperature (p< 0.05 and peripheral oxygen

  15. Razão peso/comprimento: um bom indicador do estado nutricional em recém-nascidos a termo? Weight/length ratio: is it a good index to assess the nutritional status of full-term newborns?

    Directory of Open Access Journals (Sweden)

    Taciana D. de A. Braga

    2002-01-01

    Full Text Available Objetivo: uma avaliação acurada do estado nutricional da criança ao nascer tem importância na identificação precoce de eventos mórbidos relacionados com a aceleração ou desaceleração do crescimento intra-útero. Os índices antropométricos resultantes das razões entre o peso e o comprimento e aqueles que resultam da razão entre o perímetro braquial e o perímetro cefálico podem ser uma alternativa, dentro da antropometria, para esse fim. O objetivo principal deste estudo foi verificar o grau de correlação entre a prega cutânea triciptal e os índices antropométricos - índice ponderal de Rohrer, índice de massa corpórea, razão peso/comprimento, razão perímetro braquial/perímetro cefálico - utilizados como critério de avaliação do estado nutricional de recém-nascidos. Métodos: realizou-se um estudo de corte transversal em 390 recém-nascidos a termo na maternidade do Centro de Atenção à Saúde da Mulher do Instituto Materno-Infantil de Pernambuco, no período de maio a julho de 1999. Os recém-nascidos foram avaliados quanto ao peso, comprimento, perímetros cefálico e braquial e prega cutânea triciptal. Resultados: os resultados mostraram que os índices antropométricos apresentaram correlação significante com a prega cutânea triciptal, tendo sido a razão simples entre o peso e o comprimento aquele que se correlacionou mais fortemente (r = 0,63; p Objective: An accurate assessment of the nutritional status of an infant at birth is very important, since it provides information on early identification of pathological events related to intrauterine growth acceleration or retardation. Anthropometric ratios such as weight/length and mid-arm circumference/head circumference may be used as alternative tools for this purpose. The main objective of this study was to verify the correlation between triceps skinfold thickness with Rohrer Index, Body Mass Index, weight/length ratio, and mid-arm circumference

  16. Velocimetria Doppler no período neonatal em recém-nascidos a termo pequenos para idade gestacional Neonatal Doppler velocimetry in full term small-for-gestational age newborns

    Directory of Open Access Journals (Sweden)

    Iracema Augusta Carvalho Cortez Muniz

    2003-09-01

    Full Text Available Este estudo teve como objetivo avaliar o fluxo sanguíneo cerebral em recém-nascidos a termo pequenos para idade gestacional, utilizando ultra-sonografia Doppler craniana ao nascimento. O estudo foi desenvolvido no CAISM/UNICAMP (Centro de Saúde Terciário para Mulheres. Foram selecionados sessenta recém-nascidos e divididos em 2 grupos: 36 adequados para idade gestacional (AIG e 24 pequenos para idade gestacional (PIG. Foi realizada a avaliação de ultra-sonografia Doppler craniana nos grupos, entre 24-48 horas após o nascimento. A velocidade de fluxo sanguíneo cerebral foi menor no grupo PIG na artéria cerebral anterior (ACA. As medidas Doppler foram estatisticamente diferentes entre os grupos apenas para valores relacionados à velocidade de fluxo de pico sistólico (VFPS e velocidade de fluxo médio (VFM na ACA. Não houve diferenças significantes para nenhum dos parâmetros avaliados de velocidade de fluxo na artéria cerebral média (ACM. Concluiu-se que recém-nascidos PIG apresentaram VFPS e VFM significativamente menores apenas na ACA. A adequação peso/idade gestacional, presença de policitemia neonatal e valores de pressão arterial média estiveram estatisticamente associados a VFM na ACA. A presença de sofrimento fetal, valores de pressão arterial média e hábito de fumar durante a gestação estiveram estatisticamente associados a VFM na ACM.This study aimed to evaluate the cerebral blood flow of full term small-for-gestational age newborns, using cranial ultrasound Doppler at birth. This study was performed at CAISM/UNICAMP (Tertiary Health Center for Women. Sixty term newborns were selected and divided in two groups: appropriate-for-gestational age (AGA (36 neonates and small-for-gestational age (SGA (24 neonates. Cranial ultrasound Doppler evaluation was performed on both groups, between 24 and 48 hours after birth. Cerebral blood flow velocity (CBFV was lower in the small-for-gestational age group, in the anterior

  17. Suplementação enteral e parenteral com glutamina em neonatos pré-termo e com baixo peso ao nascer Enteral and parenteral supplementation with glutamine in preterm and low-birth-weight neonates

    Directory of Open Access Journals (Sweden)

    Maria Carolina Borges

    2008-03-01

    Full Text Available A glutamina é o aminoácido livre mais abundante no sangue e no músculo esquelético, bem como é o principal substrato energético para células de elevado turnover, como enterócitos e leucócitos. Adicionalmente, a glutamina representa o principal aminoácido transferido para o feto pela placenta e, juntamente com o glutamato, constituem os aminoácidos mais abundantes no leite materno. Todavia, bebês nascidos prematuramente sofrem interrupção abrupta do fornecimento placentário de glutamina, o que acarreta em dependência exclusiva da síntese endógena ou do fornecimento exógeno deste aminoácido. Aliado a isso, neonatos pré-termo (PT e com baixo peso ao nascer (BPN, freqüentemente, recebem apenas nutrição parenteral total nas primeiras semanas de vida, a qual não contém glutamina. Cabe ainda destacar que esses bebês possuem pouca massa muscular e, portanto, seus estoques de glutamina são limitados. Uma vez que neonatos PT e com BPN estão sujeitos a intenso crescimento e a inúmeros estresses fisiológicos, é possível que a glutamina seja um nutriente condicionalmente essencial nessa fase da vida, fato que estimulou a realização de estudos com a finalidade de avaliar os possíveis benefícios clínicos da suplementação enteral e parenteral com glutamina em neonatos PT e com BPN.Glutamine is the most abundant amino acid found in the blood and skeletal muscle, and is the principal energetic substrate for cells with a high turnover, such as enterocytes and leucocytes. Furthermore, glutamine is the most important amino acid that is passed to the foetus via the placenta, and together with glutamate, is the most abundant amino acid in maternal milk. Preterm infants suffer an abrupt interruption in the supply of glutamine via the placenta, which leads to an exclusive dependence on the endogenous synthesis or the exogenous supply of this amino acid. Preterm neonates (PT as well as low-birth-weight neonates (LBW frequently

  18. Student Augmentation for Crystal Growth Research

    National Research Council Canada - National Science Library

    Prasad, V

    1999-01-01

    ... intelligent modeling, design and control of crystal growth processes. One doctoral student worked on integrating the radiation heat transfer model into MASTRAPP, the crystal growth model developed by the Consortium for Crystal Growth Research...

  19. Effects of impurities on crystal growth in fructose crystallization

    Science.gov (United States)

    Chu, Y. D.; Shiau, L. D.; Berglund, K. A.

    1989-10-01

    The influence of impurities on the crystallization of anhydrous fructose from aqueous solution was studied. The growth kinetics of fructose crystals in the fructose-water-glucose and fructose-water-difructose dianhydrides systems were investigated using photomicroscopic contact nucleation techniques. Glucose is the major impurity likely to be present in fructose syrup formed during corn wet milling, while several difructose dianhydrides are formed in situ under crystallization conditions and have been proposed as a cause in the decrease of overall yields. Both sets of impurities were found to cause inhibition of crystal growth, but the mechanisms responsible in each case are different. It was found that the presence of glucose increases the solubility of fructose in water and thus lowers the supersaturation of the solution. This is probably the main effect responsible for the decrease of crystal growth. Since the molecular structures of difructose dianhydrides are similar to that of fructose, they are probably "tailor-made" impurities. The decrease of crystal growth is probably caused by the incorporation of these impurities into or adsorption to the crystal surface which would accept fructose molecules in the orientation that existed in the difructose dianhydride.

  20. Nanoparticles in liquid crystals, and liquid crystals in nanoparticles

    Science.gov (United States)

    de Pablo, Juan

    2015-03-01

    Liquid crystals are remarkably sensitive to interfacial interactions. Small perturbations at a liquid crystal interface, for example, can be propagated over relatively long length scales, thereby providing the basis for a wide range of applications that rely on amplification of molecular events into macroscopic observables. Our recent research efforts have focused on the reverse phenomenon; that is, we have sought to manipulate the interfacial assembly of nanoparticles or the organization of surface active molecules by controlling the structure of a liquid crystal. This presentation will consist of a review of the basic principles that are responsible for liquid crystal-mediated interactions, followed by demonstrations of those principles in the context of two types of systems. In the first, a liquid crystal is used to direct the assembly of nanoparticles; through a combination of molecular and continuum models, it is found that minute changes in interfacial energy and particle size lead to liquid-crystal induced attractions that can span multiple orders of magnitude. Theoretical predictions are confirmed by experimental observations, which also suggest that LC-mediated assembly provides an effective means for fabrication of plasmonic devices. In the second type of system, the structure of a liquid crystal is controlled by confinement in submicron droplets. The morphology of the liquid crystal in a drop depends on a delicate balance between bulk and interfacial contributions to the free energy; that balance can be easily perturbed by adsorption of analytes or nanoparticles at the interface, thereby providing the basis for development of hierarchical assembly of responsive, anisotropic materials. Theoretical predictions also indicate that the three-dimensional order of a liquid crystal can be projected onto a two-dimensional interface, and give rise to novel nanostructures that are not found in simple isotropic fluids.

  1. Dichroic Liquid Crystal Displays

    Science.gov (United States)

    Bahadur, Birendra

    The following sections are included: * INTRODUCTION * DICHROIC DYES * Chemical Structure * Chemical and Photochemical Stability * THEORETICAL MODELLING * DEFECTS CAUSED BY PROLONGED LIGHT IRRADIATION * CHEMICAL STRUCTURE AND PHOTOSTABILITY * OTHER PARAMETERS AFFECTING PHOTOSTABILITY * CELL PREPARATION * DICHROIC PARAMETERS AND THEIR MEASUREMENTS * Order Parameter and Dichroic Ratio Of Dyes * Absorbance, Order Parameter and Dichroic Ratio Measurements * IMPACT OF DYE STRUCTURE AND LIQUID CRYSTAL HOST ON PHYSICAL PROPERTIES OF A DICHROIC MIXTURE * Order Parameter and Dichroic Ratio * EFFECT OF LENGTH OF DICHROIC DYES ON THE ORDER PARAMETER * EFFECT OF THE BREADTH OF DYE ON THE ORDER PARAMETER * EFFECT OF THE HOST ON THE ORDER PARAMETER * TEMPERATURE VARIATION OF THE ORDER PARAMETER OF DYES IN A LIQUID CRYSTAL HOST * IMPACT OF DYE CONCENTRATION ON THE ORDER PARAMETER * Temperature Range * Viscosity * Dielectric Constant and Anisotropy * Refractive Indices and Birefringence * solubility43,153-156 * Absorption Wavelength and Auxochromic Groups * Molecular Engineering of Dichroic Dyes * OPTICAL, ELECTRO-OPTICAL AND LIFE PARAMETERS * Colour And CIE Colour space120,160-166 * CIE 1931 COLOUR SPACE * CIE 1976 CHROMATICITY DIAGRAM * CIE UNIFORM COLOUR SPACES & COLOUR DIFFERENCE FORMULAE120,160-166 * Electro-Optical Parameters120 * LUMINANCE * CONTRAST AND CONTRAST RATIO * SWITCHING SPEED * Life Parameters and Failure Modes * DICHROIC MIXTURE FORMULATION * Monochrome Mixture * Black Mixture * ACHROMATIC BLACK MIXTURE FOR HEILMEIER DISPLAYS * Effect of Illuminant on Display Colour * Colour of the Field-On State * Effect of Dye Linewidth * Optimum Centroid Wavelengths * Effect of Dye Concentration * Mixture Formulation Using More Than Three Dyes * ACHROMATIC MIXTURE FOR WHITE-TAYLOR TYPE DISPLAYS * HEILMEIER DISPLAYS * Theoretical Modelling * Threshold Characteristic * Effects of Dye Concentration on Electro-optical Parameters * Effect of Cholesteric Doping * Effect of Alignment

  2. Pressure sensor using liquid crystals

    Science.gov (United States)

    Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

    1994-01-01

    A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.

  3. Spatial filtering with photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Maigyte, Lina [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Staliunas, Kestutis [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, Barcelona 08010 (Spain)

    2015-03-15

    Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

  4. Crystal ball single event display

    International Nuclear Information System (INIS)

    Grosnick, D.; Gibson, A.; Allgower, C.; Alyea, J.; Argonne National Lab., IL

    1997-01-01

    The Single Event Display (SED) is a routine that is designed to provide information graphically about a triggered event within the Crystal Ball. The SED is written entirely in FORTRAN and uses the CERN-based HICZ graphing package. The primary display shows the amount of energy deposited in each of the NaI crystals on a Mercator-like projection of the crystals. Ten different shades and colors correspond to varying amounts of energy deposited within a crystal. Information about energy clusters is displayed on the crystal map by outlining in red the thirteen (or twelve) crystals contained within a cluster and assigning each cluster a number. Additional information about energy clusters is provided in a series of boxes containing useful data about the energy distribution among the crystals within the cluster. Other information shown on the event display include the event trigger type and data about π o 's and η's formed from pairs of clusters as found by the analyzer. A description of the major features is given, along with some information on how to install the SED into the analyzer

  5. Crystallization of copper metaphosphate glass

    Science.gov (United States)

    Bae, Byeong-Soo; Weinberg, Michael C.

    1993-01-01

    The effect of the valence state of copper in copper metaphosphate glass on the crystallization behavior and glass transition temperature has been investigated. The crystallization of copper metaphosphate is initiated from the surface and its main crystalline phase is copper metaphosphate (Cu(PO)3),independent of the (Cu sup 2+)/(Cu(total)). However, the crystal morphology, the relative crystallization rates, and their temperature dependences are affected by the (Cu sup 2+)/(Cu (total)) ratio in the glass. On the other hand, the totally oxidized glass crystallizes from all over the surface. The relative crystallization rate of the reduced glass to the totally oxidized glass is large at low temperature, but small at high temperature. The glass transition temperature of the glass increases as the (Cu sup 2+)/(Cu(total)) ratio is raised. It is also found that the atmosphere used during heat treatment does not influence the crystallization of the reduced glass, except for the formation of a very thin CuO surface layer when heated in air.

  6. Crystallization in polydisperse colloidal suspensions

    International Nuclear Information System (INIS)

    Martin, S.; Bryant, G.; Van Megen, W.

    2004-01-01

    Full text: Crystallization and glass formation in colloidal hard spheres has been a very active area of research over the last 15-20 years. For most of this time particle polydispersity has been considered to be a minor concern in these studies. However, over the last few years an increasing number of simulations, theoretical work and experiments have shown that consideration of the polydispersity is critical in understanding these phenomena. In this paper we provide an overview of recent crystallization studies on particles with two very different particle size distributions. These particles exhibit very different equilibrium crystal structures and crystallization kinetics. Based on these measurements and time lapse photographs, we propose a growth mechanism whereby crystallization occurs in conjunction with a local fractionation process near the crystal-fluid interface, which significantly alters the kinetics of crystallite nucleation and growth. This fractionation effect becomes more significant as polydispersity or skewness increases. The unusual crystal structures observed are explained using a schematic model that explains the structure in terms of stacks of planes, which are unregistered due to a high incidence of stacking faults caused by the incorporation of a large number of small particles

  7. Changes in copper sulfate crystal habit during cooling crystallization

    Science.gov (United States)

    Giulietti, M.; Seckler, M. M.; Derenzo, S.; Valarelli, J. V.

    1996-09-01

    The morphology of technical grade copper(II) sulfate pentahydrate crystals produced from batch cooling experiments in the temperature range of 70 to 30°C is described and correlated with the process conditions. A slow linear cooling rate (batch time of 90 min) predominantly caused the appearance of well-formed crystals. Exponential cooling (120 min) resulted in the additional formation of agglomerates and twins. The presence of seeds for both cooling modes led to round crystals, agglomerates and twins. Fast linear cooling (15 min) gave rise to a mixture of the former types. Broken crystals and adhering fragments were often found. Growth zoning was pronounced in seeded and linear cooling experiments. Fluid inclusions were always found and were more pronounced for larger particles. The occurrence of twinning, zoning and fluid inclusions was qualitatively explained in terms of fundamental principles.

  8. Thermal expansion of LATGS crystals

    International Nuclear Information System (INIS)

    Kassem, M.E.; Kandil, S.H.; Hamed, A.E.; Stankowska, J.

    1989-04-01

    The thermal expansion of triglycine sulphate crystals doped with L-α alanine (LATGS) has been studied around the phase transition temperature (30-60 deg. C) using thermomechanical analysis TMA. With increasing the content of admixture, the transition temperature (T c ) was shifted towards higher values, while the relative changes in the dimension of the crystals (ΔL/L 0 ) of the studied directions varied both in the para- and ferroelectric phases. The transition width in the case of doped crystals was found to be broad, and this broadening increases with increasing the content of L-α alanine. (author). 12 refs, 3 figs

  9. Crystallization peculiarities in metallic glasses

    International Nuclear Information System (INIS)

    Serebryakov, A.V.; Abrosimova, G.E.; Aronin, A.S.

    1985-01-01

    Methods of X-ray electron microscopy and X-ray diffraction analysis were used to investigate the peculiarities of crystallization of amorphous metallic Fe-B and Fe-Si-B alloys related to sufficient change of volume when passing from amorphous to crystalline state and the effect of sample prehistory on its thermal stability and crystallization kinetics. The dependence of morphology of crystalline phases formed during crystallization of amorphous Fe-B alloys on sample thickness was revealed and investigated. The model explaining this dependence was suggested. The observed differences are related, according to the model, with different diffusion ways of ''poles'' - elementary carriers of empty volume to their sinks

  10. Crystal structure determination of Efavirenz

    International Nuclear Information System (INIS)

    Popeneciu, Horea; Dumitru, Ristoiu; Tripon, Carmen; Borodi, Gheorghe; Pop, Mihaela Maria

    2015-01-01

    Needle-shaped single crystals of the title compound, C 14 H 9 ClF 3 NO 2 , were obtained from a co-crystallization experiment of Efavirenz with maleic acid in a (1:1) ratio, using methanol as solvent. Crystal structure determination at room temperature revealed a significant anisotropy of the lattice expansion compared to the previously reported low-temperature structure. In both low- and room temperature structures the cyclopropylethynyl fragment in one of the asymmetric unit molecules is disordered. While at low-temperature only one C atom exhibits positional disorder, at room temperature the disorder is present for two C atoms of the cyclopropane ring

  11. Random photonic crystal optical memory

    International Nuclear Information System (INIS)

    Wirth Lima Jr, A; Sombra, A S B

    2012-01-01

    Currently, optical cross-connects working on wavelength division multiplexing systems are based on optical fiber delay lines buffering. We designed and analyzed a novel photonic crystal optical memory, which replaces the fiber delay lines of the current optical cross-connect buffer. Optical buffering systems based on random photonic crystal optical memory have similar behavior to the electronic buffering systems based on electronic RAM memory. In this paper, we show that OXCs working with optical buffering based on random photonic crystal optical memories provides better performance than the current optical cross-connects. (paper)

  12. The influence of gestational age and birth weight in the clinical assesment of the muscle tone of healthy term and preterm newborns A influência da idade gestacional e do peso ao nascimento na avaliação clínica do tono muscular de recém nascidos a termo e prematuros hígidos

    Directory of Open Access Journals (Sweden)

    Edla S. da Silva

    2005-12-01

    Full Text Available OBJECTIVE: To evaluate the influence of gestational age (GA and birth weight (BW in the clinical assessment of the muscle tone of healthy term and preterm newborns. METHOD: Cross sectional study. The muscle tone of healthy 42 preterm and 47 term newborns was quantified and measured with a goniometer (an instrument for measuring angles respectively between 7th-14th day of life and 24-48 hours of life. Newborns were grouped according to GA and BW and evaluated at fixed time intervals by one examiner. Preterm newborns were matched to term at 40 weeks postconceptional age (PCA. RESULTS: The evolution of muscle tone in the preterm occurred gradually, following PCA, independent of birth weight. Preterm newborns had lower scores in all muscle tone indicators when compared to term at the first assessment. Differences were observed among preterm small for GA and adequate to GA for the indicator heel to ear (pOBJETIVO: Verificar a influência da idade gestacional (IG e do peso ao nascimento (PN na avaliação do tono muscular de recém nascidos (RN a termo e prematuros hígidos. MÉTODO: Estudo transversal. O tono muscular de 42 RN prematuros e 47 termo foi quantificado e mensurado com goniômetro (instrumento para medir ângulos, respectivamente entre 7-14 dias de vida e 24-48 horas de vida. Os RN foram agrupados de acordo com IG e PN, sendo avaliados em intervalos fixos. RN prematuros foram comparados aos a termo na 40ª semana de idade concepcional (IC. RESULTADOS: A evolução do tono muscular nos RN prematuros ocorreu de forma gradual de acordo com IC e independente do PN. RN prematuros, na primeira avaliação apresentaram escores de tono muscular inferiores aos de RN a termo em todos os indicadores. Foram observadas diferenças entre RN prematuros pequenos e adequados para a IG em relação ao indicador calcanhar-orelha (p<0,001. O pareamento dos grupos na 40ª semana de IC mostra, exceto pela postura, diferença significativa entre os grupos (p< 0

  13. Desenvolvimento motor de crianças prematuras e a termo: uso da Alberta Infant Motor Scale Desarrollo motor de niños prematuros y a término: uso de la Alberta Infant Motor Scale Motor development of preterm and term infants: using the Alberta Infant Motor Scale

    Directory of Open Access Journals (Sweden)

    Polyana Candeia Maia

    2011-01-01

    Full Text Available OBJETIVOS: Comparar o desenvolvimento motor de crianças nascidas pré-termo e a termo aos quatro e seis meses de idade, aplicando a Alberta Infant Motor Scale-AIMS na versão brasileira. MÉTODOS: Estudo longitudinal, comparativo, realizado em Fortaleza-Ceará, entre novembro/ 2009 e maio/2010. amostragem por conveniência, foi constituída por 24 crianças pré-termo e 24 a termo. RESULTADOS: Nas crianças de quatro meses, verificou-se diferença estatisticamente significante na posição em pé (p=0,014 e, nas de seis meses, em todas as posições (prono, supina, sentada, em pé e escores totais. Quanto ao percentil, aos quatro e seis meses, respectivamente, 37,5% das crianças pré-termo mostraram desempenho excelente e 54,2%, normais. CONCLUSÃO: A análise estatística do desempenho motor grosso entre os grupos de crianças estudadas mostrou diferenças no desenvolvimento e evolução dos percentis da AIMS.OBJETIVOS: Comparar el desarrollo motor de niños nacidos pretérmino y a término a los cuatro y seis meses de edad, aplicando la Alberta Infant Motor Scale-AIMS en la versión brasileña. MÉTODOS: Estudio longitudinal, comparativo, realizado en Fortaleza-Ceará, entre noviembre/2009 y mayo/2010. La muestra por conveniencia, estuvo constituída por 24 niños pretérmino y 24 a término. RESULTADOS: En los niños de cuatro meses, se verificó una diferencia estadísticamente significativa en la posición podálica (p=0,014 y, en las de seis meses, en todas las posiciones (prona, supina, sentada, podálica y scores totales. En cuanto al percentil, a los cuatro y seis meses, respectivamente, el 37,5% de los niños pretérmino mostraron desempeño excelente y el 54,2%, normales. CONCLUSIÓN: El análisis estadístico del desempeño motor grueso entre los grupos de niños estudiados mostró diferencias en el desarrollo y evolución de los percentiles de la AIMS.OBJECTIVES: To compare the motor development of infants born preterm and term at

  14. Crystal plasticity study of single crystal tungsten by indentation tests

    International Nuclear Information System (INIS)

    Yao, Weizhi

    2012-01-01

    Owing to its favorable material properties, tungsten (W) has been studied as a plasma-facing material in fusion reactors. Experiments on W heating in plasma sources and electron beam facilities have shown an intense micro-crack formation at the heated surface and sub-surface. The cracks go deep inside the irradiated sample, and often large distorted areas caused by local plastic deformation are present around the cracks. To interpret the crack-induced microscopic damage evolution process in W, one needs firstly to understand its plasticity on a single grain level, which is referred to as crystal plasticity. In this thesis, the crystal plasticity of single crystal tungsten (SCW) has been studied by spherical and Berkovich indentation tests and the finite element method with a crystal plasticity model. Appropriate values of the material parameters included in the crystal plasticity model are determined by fitting measured load-displacement curves and pile-up profiles with simulated counterparts for spherical indentation. The numerical simulations reveal excellent agreement with experiment. While the load-displacement curves and the deduced indentation hardness exhibit little sensitivity to the indented plane at small indentation depths, the orientation of slip directions within the crystals governs the development of deformation hillocks at the surface. It is found that several factors like friction, indentation depth, active slip systems, misoriented crystal orientation, misoriented sample surface and azimuthal orientation of the indenter can affect the indentation behavior of SCW. The Berkovich indentation test was also used to study the crystal plasticity of SCW after deuterium irradiation. The critical load (pop-in load) for triggering plastic deformation under the indenter is found to depend on the crystallographic orientation. The pop-in loads decrease dramatically after deuterium plasma irradiation for all three investigated crystallographic planes.

  15. Single Crystal Surfaces

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2014-06-01

    The present work studies (0001) Al2O3 and (111) Al2MgO4 wetting with pure molten Al by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) under Ar at PO2 10-15 Pa. Al pure liquid wets a smooth and chemically homogeneous surface of an inert solid, the wetting driving force ( t, T) can be readily studied when surface solid roughness increases in the system. Both crystals planes (0001) Al2O3 and (111) Al2MgO4 have crystallographic surfaces with identical O-2 crystalline positions however considering Mg2+ content in Al2MgO4 structure may influence a reactive mode. Kinetic models results under similar experimental conditions show that Al wetting on (0001) Al2O3 is less reactive than (111) Al2MgO4, however at >1273 K (1000 °C) (0001) Al2O3 transformation occurs and a transition of wetting improves. The (111) Al2MgO4 and Al system promotes interface formations that slow its wetting process.

  16. Patterned Colloidal Photonic Crystals.

    Science.gov (United States)

    Hou, Jue; Li, Mingzhu; Song, Yanlin

    2018-03-01

    Colloidal photonic crystals (PCs) have been well developed because they are easy to prepare, cost-effective, and versatile with regards to modification and functionalization. Patterned colloidal PCs contribute a novel approach to constructing high-performance PC devices with unique structures and specific functions. In this review, an overview of the strategies for fabricating patterned colloidal PCs, including patterned substrate-induced assembly, inkjet printing, and selective immobilization and modification, is presented. The advantages of patterned PC devices are also discussed in detail, for example, improved detection sensitivity and response speed of the sensors, control over the flow direction and wicking rate of microfluidic channels, recognition of cross-reactive molecules through an array-patterned microchip, fabrication of display devices with tunable patterns, well-arranged RGB units, and wide viewing-angles, and the ability to construct anti-counterfeiting devices with different security strategies. Finally, the perspective of future developments and challenges is presented. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Crystal structure of pymetrozine

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2015-07-01

    Full Text Available The title compound, C10H11N5O {systematic name: 6-methyl-4-[(E-(pyridin-3-ylmethylideneamino]-4,5-dihydro-1,2,4-triazin-3(2H-one}, C10H11N5O, is used as an antifeedant in pest control. The asymmetric unit comprises two independent molecules, A and B, in which the dihedral angles between the pyridinyl and triazinyl ring planes [r.m.s. deviations = 0.0132 and 0.0255 ] are 11.60 (6 and 18.06 (4°, respectively. In the crystal, N—H...O, N—H...N, C—H...N and C—H...O hydrogen bonds, together with weak π–π interactions [ring-centroid separations = 3.5456 (9 and 3.9142 (9 Å], link the pyridinyl and triazinyl rings of A molecules, generating a three-dimensional network.

  18. Environmental effects of the TermoPernambuco; Impactos ambientais da TermoPernambuco

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves Filho, Luiz Carlos; Costa, Heitor Scalambrini [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Nucleo de Apoio a Projetos de Energias Renovaveis]. E-mail: naper@ufpe.br

    2006-07-01

    In a world scale, 80% of the total energy consumed by mankind comes fossil fuel (charcoal, petroleum and natural gas). The massive use of that energy resource has lead to the exhaustion of its reserves and has turned itself into a real menace to the environment, as a consequence of the earth global warming (greenhouse effect), of the risk to the public health and of the acidification of the water cycle. Whenever that type of fuel is burned in thermoelectric power plants, in transportation vehicles and in the industry, it liberates highly toxic gases and other pollutants (carbonic gas, nitrogen oxides, sulfur dioxide, among others), which are largely the responsible for the mentioned environmental impacts to the point of putting at stake the very survival of the human race. In the context of the Thermoelectricity Priority Program, launched by the federal government in February 24th, 2000 (Decree 3.371), the Pernambuco State Government has authorized the construction of a thermoelectric power plant powered by natural gas - the Thermo Pernambuco - in the harbor region of Suape, with a installed capacity of generating 520 MW. In this work the environmental impacts of the Thermo Pernambuco are shown in which concerns to the production of toxic gases. Those results were obtained through a bibliographic research about similar situations and through the detailed analysis of the EIA/RIMA reports (needed for the complying with the Brazilian environmental laws). We show that that plant will be responsible for a considerable increase in the air pollution. Considering an 80% capacity factor , that is, the power plant operating for 7,000 hours per year, it will send yearly 1.8 million ton of C0{sub 2} (5,000 per day) and 836 ton of No{sub x} (2.3 ton per day). (author)

  19. Channeling crystals for positron production

    International Nuclear Information System (INIS)

    Decker, F.J.

    1991-05-01

    Particles traversing at small angles along a single crystal axis experience a collective scattering force of many crystal atoms. The enormous fields can trap the particles along an axis or plane, called channeling. High energy electrons are attracted by the positive nuclei and therefore produce strongly enhanced so called coherent bremsstrahlung and pair production. These effects could be used in a positron production target: A single tungsten crystal is oriented to the incident electron beam within 1 mrad. At 28 GeV/c the effective radiation length is with 0.9 mm about one quarter of the amorphous material. So the target length can be shorter, which yields a higher conversion coefficient and a lower emittance of the positron beam. This makes single crystals very interesting for positron production targets. 18 refs., 2 figs

  20. Molecular mechanisms of crystal growth

    International Nuclear Information System (INIS)

    Pina, C. M.

    2000-01-01

    In this paper I present an example of the research that the Mineral Surface Group of the Munster University is conducting in the field of Crystal Growth. Atomic Force Microscopy (Am) in situ observations of different barite (BaSO4) faces growing from aqueous solutions, in combination with computer simulations of the surface attachment of growth units allows us to test crystal growth models. Our results demonstrate the strong structural control that a crystal can exert on its own growth, revealing also the limitation of the classical crystal growth theories (two dimensional nucleation and spiral growth models) in providing a complete explanation for the growth behaviour at a molecular scale. (Author) 6 refs

  1. Size effects in crystal plasticity

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    Numerical analyses of plasticity size effects have been carried out for different problems using a developed strain gradient crystal plasticiy theory. The theory employs higher order stresses as work conjugates to slip gradients and uses higher order boundary conditions. Problems on localization...... of plastic flow in a single crystal, grain boundary effects in a bicrystal, and grain size effects in a polycrystal are studied. Single crystals containing micro-scale voids have also been analyzed at different loading conditions with focus on the stress and deformation fields around the voids, on void...... growth and interaction between neighboring voids, and on a comparison between the developed strain gradient crystal plasticity theory and a discrete dislocation plasticity theory. Furthermore, voids and rigid inclusions in isotropic materials have been studied using a strain gradient plasticity theory...

  2. SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURES ...

    African Journals Online (AJOL)

    B. S. Chandravanshi

    ABSTRACT. Reaction of [VO(acac)2] (acac = acetylacetonate) with ... Single crystal X-ray structural studies indicate that the hydrazone ligands coordinate to ..... Molecular structure of complex (1) at 30% probability displacement. Figure 4.

  3. SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE ...

    African Journals Online (AJOL)

    Preferred Customer

    Reaction of [MoO2(acac)2] (where acac = acetylacetonate) with N'-(2-hydroxy-4- ... Single crystal X-ray structural studies indicate that the hydrazone ligand coordinates .... Molecular structure of the complex at 30% probability displacement.

  4. SYNTHESIS, CHARACTERIZATION, AND CRYSTAL STRUCTURE ...

    African Journals Online (AJOL)

    a

    KEY WORDS: Barium, Crystal structure, 2,6-Pyridinedicarboxylic acid .... The rational design of novel metal-organic frameworks has attracted great ..... Bond, A.D.; Jones, W. Supramolecular Organization and Materials Design, Jones, W.; Rao,.

  5. Absence of Quantum Time Crystals.

    Science.gov (United States)

    Watanabe, Haruki; Oshikawa, Masaki

    2015-06-26

    In analogy with crystalline solids around us, Wilczek recently proposed the idea of "time crystals" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state or in the canonical ensemble of a general Hamiltonian, which consists of not-too-long-range interactions.

  6. Magnonic crystals for data processing

    International Nuclear Information System (INIS)

    Chumak, A V; Serga, A A; Hillebrands, B

    2017-01-01

    Magnons (the quanta of spin waves) propagating in magnetic materials with wavelengths at the nanometer-scale and carrying information in the form of an angular momentum can be used as data carriers in next-generation, nano-sized low-loss information processing systems. In this respect, artificial magnetic materials with properties periodically varied in space, known as magnonic crystals, are especially promising for controlling and manipulating magnon currents. In this article, different approaches for the realization of static, reconfigurable, and dynamic magnonic crystals are presented along with a variety of novel wave phenomena discovered in these crystals. Special attention is devoted to the utilization of magnonic crystals for processing of analog and digital information. (paper)

  7. Nanoparticles Doped, Photorefractive Liquid Crystals

    National Research Council Canada - National Science Library

    Kaczmarek, Malgosia

    2005-01-01

    ...: The main objectives of this exploratory, short project will concern the study of the quality of liquid crystal cells with diluted suspensions of ferroelectric nanoparticles and their photorefractive properties...

  8. Protein Crystal Recombinant Human Insulin

    Science.gov (United States)

    1994-01-01

    The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

  9. Modeling of photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Barkou, Stig Eigil

    1999-01-01

    Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated.......Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated....

  10. Semiconductor crystal high resolution imager

    Science.gov (United States)

    Levin, Craig S. (Inventor); Matteson, James (Inventor)

    2011-01-01

    A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).

  11. Charge transport in organic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ortmann, Frank

    2009-07-01

    The understanding of charge transport is one of the central goals in the research on semiconducting crystals. For organic crystals this is particularly complicated due to the strength of the electron-phonon interaction which requires the description of a seamless transition between the limiting cases of a coherent band-transport mechanism and incoherent hopping. In this thesis, charge transport phenomena in organic crystals are studied by theoretical means. A theory for charge transport in organic crystals is developed which covers the whole temperature range from low T, where it reproduces an expression from the Boltzmann equation for band transport, via elevated T, where it generalizes Holstein's small-polaron theory to finite bandwidths, up to high T, for which a temperature dependence equal to Marcus' electron-transfer theory is obtained. Thereby, coherent band transport and thermally induced hopping are treated on equal footing while simultaneously treating the electron-phonon interaction non-perturbatively. By avoiding the approximation of narrow polaron bands the theory allows for the description of large and small polarons and serves as a starting point for computational studies. The theoretical description is completed by using ab initio material parameters for the selected crystals under study. These material parameters are taken from density functional theory calculations for durene, naphthalene, and guanine crystals. Besides the analysis of the transport mechanism, special focus is put on the study of the relationship between mobility anisotropy and structure of the crystals. This study is supported by a 3D-visualization method for the transport channels in such crystals which has been derived in this thesis. (orig.)

  12. Polariton effects in naphthalene crystals

    International Nuclear Information System (INIS)

    Robinette, S.L.

    1977-10-01

    The experimental verification of the two-step nature of energy dissipation of photon energy by a crystal is the subject of this dissertation. The α(O,O) Davydov component of the lowest energy singlet transition in pure strain-free napthalene single crystals is shown to exhibit an increase in absorption with increasing temperature, due to an increase in polariton damping via polariton-phonon scattering processes

  13. Adaptive Liquid Crystal Windows

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31

    Energy consumption by private and commercial sectors in the U.S. has steadily grown over the last decade. The uncertainty in future availability of imported oil, on which the energy consumption relies strongly, resulted in a dramatic increase in the cost of energy. About 20% of this consumption are used to heat and cool houses and commercial buildings. To reduce dependence on the foreign oil and cut down emission of greenhouse gases, it is necessary to eliminate losses and reduce total energy consumption by buildings. To achieve this goal it is necessary to redefine the role of the conventional windows. At a minimum, windows should stop being a source for energy loss. Ideally, windows should become a source of energy, providing net gain to reduce energy used to heat and cool homes. It is possible to have a net energy gain from a window if its light transmission can be dynamically altered, ideally electronically without the need of operator assistance, providing optimal control of the solar gain that varies with season and climate in the U.S. In addition, the window must not require power from the building for operation. Resolution of this problem is a societal challenge and of national interest and will have a broad global impact. For this purpose, the year-round, allclimate window solution to provide an electronically variable solar heat gain coefficient (SHGC) with a wide dynamic range is needed. AlphaMicron, Inc. (AMI) developed and manufactured 1ft × 1ft prototype panels for the world’s first auto-adjusting Adaptive Liquid Crystal Windows (ALCWs) that can operate from sunlight without the need for external power source and demonstrate an electronically adjustable SHGC. This novel windows are based on AlphaMicron’s patented e-Tint® technology, a guesthost liquid crystal system implemented on flexible, optically clear plastic films. This technology is suitable both for OEM and aftermarket (retro-fitting) lamination to new and existing windows. Low level of

  14. Protein crystal nucleation in pores.

    Science.gov (United States)

    Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E

    2017-01-16

    The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the pore is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the pore walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.

  15. Hydrothermal Growth of Polyscale Crystals

    Science.gov (United States)

    Byrappa, Kullaiah

    In this chapter, the importance of the hydrothermal technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the hydrothermal technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine hydrothermal research, including the continuous production of nanosize crystals, are discussed. The latest trends in the hydrothermal growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the hydrothermal technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the hydrothermal technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.

  16. Spin waves in quantum crystals

    International Nuclear Information System (INIS)

    Kondratenko, P.S.

    1975-01-01

    The paper considers the spectrum of spin waves of a quantum magnetic crystal. It has been assumed that the crystal is characterized by gapless Fermi excitations. The properties of a single-particle Green function for a magnetic crystal are briefly outlined. The dispersion equation system describing the spin wave spectrum has been derived. The spectrum described by the equation system comprises a group of Goldstone modes and a family of spin waves of the zero sound type, associated with the group by an interaction. The maximum number of Goldstone modes in an antiferromagnet is three, whereas in a ferromagnet it is two. At frequencies higher than the characteristic frequencies of magnetic interactions, in an antiferromagnet all three modes have a linear spectrum, whereas in a ferromagnet the longitudinal mode is represented by a linear spectrum and the transverse mode, by a quadratic one. The dynamical susceptibility of a magnetically ordered crystal has been calculated. The thermodynamical potential of the crystal has been proved to vary as a function of the angular crystal orientation in a spin subspace. The results have been obtained by methods of the quantum field theory for the case of zero temperature

  17. Avaliação do teste de respiração espontânea na extubação de neonatos pré-termo Spontaneous breathing trial evaluation in preterm newborns extubation

    Directory of Open Access Journals (Sweden)

    Lívia Barboza Andrade

    2010-06-01

    Full Text Available OBJETIVO: O teste de respiração espontânea (TRE antes da extubação fornece informações sobre a capacidade de respirar espontaneamente. O objetivo desse estudo foi verificar se o TRE é preditor de sucesso da extubação. MÉTODOS: Estudo de perfil observacional, longitudinal e prospectivo. Após eleitos para extubação, 60 recém nascidos pré-termo foram divididos em dois grupos: TRE (n= 30, pressão positiva contínua de vias aéreas durante 30 minutos, e controle (n=30, extubados sem o teste. Foram avaliados antes, aos 10, 20 e 30 minutos do grupo TRE, a freqüência respiratória e cardíaca, saturação de pulso de oxigênio e boletim de Silverman e Andersen. Peso, idade gestacional, Apgar, pressão média de vias aéreas, fração inspirada de oxigênio (FiO2 e tempo de cânula orotraqueal foram analisadas intra-grupos e quanto ao sucesso e falha na extubação. O Qui-quadrado para associações das variáveis categóricas e Mann-Whitney para distribuição não-normal. O sucesso na extubação foi 48 horas sem necessidade de reintubação. RESULTADOS: Não houve diferença significante nas variáveis analisadas, exceto pressão média de vias aéreas. As variáveis analisadas durante o TRE (freqüência respiratória e cardíaca, saturação de oxigênio e boletim de Silverman e Andersen não demonstraram alterações significantes. Comparado sucesso e falha na extubação houve diferença significativa para FiO2 e peso atual no controle, indicando que a FiO2 maior e o peso menor indicam falha na extubação. Houve associação significante entre realização do TRE e sucesso na extubação. CONCLUSÃO: Houve associação significante do TRE e o sucesso na extubação, indicando que, no grupo que realizou o teste observou-se maior sucesso na extubação comparado ao controle.OBJECTIVE: Neonates mechanic ventilation weaning has become a major clinical challenge, and constitutes a large portion of neonatal intensive care units

  18. Second crystal cooling on cryogenically cooled undulator and wiggler double crystal monochromators

    International Nuclear Information System (INIS)

    Knapp, G. S.

    1998-01-01

    Simple methods for the cooling of the second crystals of cryogenically cooled undulator and wiggler double crystal monochromators are described. Copper braids between the first and second crystals are used to cool the second crystals of the double crystal monochromators. The method has proved successful for an undulator monochromator and we describe a design for a wiggler monochromator

  19. Phase-field crystal simulation facet and branch crystal growth

    Science.gov (United States)

    Chen, Zhi; Wang, Zhaoyang; Gu, Xinrui; Chen, Yufei; Hao, Limei; de Wit, Jos; Jin, Kexin

    2018-05-01

    Phase-field crystal model with one mode is introduced to describe morphological transition. The relationship between growth morphology and smooth density distribution was investigated. The results indicate that the pattern selection of dendrite growth is caused by the competition between interface energy anisotropy and interface kinetic anisotropy based on the 2D phase diagram. When the calculation time increases, the crystal grows to secondary dendrite at the dimensionless undercooling equal to - 0.4. Moreover, when noise is introduced in the growth progress, the symmetry is broken in the growth mode, and there becomes irregular fractal-like growth morphology. Furthermore, the single crystal shape develops into polycrystalline when the noise amplitude is large enough. When the dimensionless undercooling is less than - 0.3, the noise has a significant effect on the growth shape. In addition, the growth velocity of crystal near to liquid phase line is slow, while the shape far away from the liquid adapts to fast growth. Based on the simulation results, the method was proved to be effective, and it can easily obtain different crystal shapes by choosing the different points in 2D phase diagram.

  20. A multistep single-crystal-to-single-crystal bromodiacetylene dimerization

    Science.gov (United States)

    Hoheisel, Tobias N.; Schrettl, Stephen; Marty, Roman; Todorova, Tanya K.; Corminboeuf, Clémence; Sienkiewicz, Andrzej; Scopelliti, Rosario; Schweizer, W. Bernd; Frauenrath, Holger

    2013-04-01

    Packing constraints and precise placement of functional groups are the reason that organic molecules in the crystalline state often display unusual physical or chemical properties not observed in solution. Here we report a single-crystal-to-single-crystal dimerization of a bromodiacetylene that involves unusually large atom displacements as well as the cleavage and formation of several bonds. Density functional theory computations support a mechanism in which the dimerization is initiated by a [2 + 1] photocycloaddition favoured by the nature of carbon-carbon short contacts in the crystal structure. The reaction proceeded up to the theoretical degree of conversion without loss of crystallinity, and it was also performed on a preparative scale with good yield. Moreover, it represents the first synthetic pathway to (E)-1,2-dibromo-1,2-diethynylethenes, which could serve as synthetic intermediates for the preparation of molecular carbon scaffolds. Our findings both extend the scope of single-crystal-to-single-crystal reactions and highlight their potential as a synthetic tool for complex transformations.

  1. Prediction of molecular crystal structures

    International Nuclear Information System (INIS)

    Beyer, Theresa

    2001-01-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol -1 of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

  2. Prediction of molecular crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Theresa

    2001-07-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol{sup -1} of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

  3. Uso do copo e da mamadeira e o aleitamento materno em recém-nascidos prematuros e a termo: uma revisão sistemática Cup and bottle feeding and breastfeeding in premature and term infants: a systematic review

    Directory of Open Access Journals (Sweden)

    Cínthia Tiago Paes de Almeida Pedras

    2008-03-01

    Full Text Available OBJETIVOS: revisar ensaios clínicos randomizados que avaliaram a prevalência e/ou duração do aleitamento materno na alta hospitalar e/ou durante o primeiro ano de vida, em recém-nascidos a termo ou prematuros. Foram selecionados estudos que incluíram neonatos e que receberam suplementação por copo ou por mamadeira, durante a estadia hospitalar. MÉTODOS: foram pesquisados artigos publicados em português ou inglês, no período de 1966 a 2006, nas bases de dados Medline, Lilacs e Scielo. Os seguintes termos foram utilizados: "amamentação + mamadeira" combinado com "prevalência", "métodos de alimentação", "duração", "baixo peso", "prematuro" e "recém-nascido". RESULTADOS: cinco artigos preencheram os critérios de inclusão, suas casuísticas variaram de 14 a 686 recém-nascidos, totalizando 1552 crianças. O uso do copo para a suplementação da amamentação foi associado a maior prevalência de aleitamento materno em neonatos a termo, nascidos de parto cesárea e em prematuros no momento da alta hospitalar. CONCLUSÕES: parece haver uma influência favorável do uso do copo sobre o aleitamento materno, embora a presente revisão não seja conclusiva e definitiva.OBJECTIVES: to review randomized clinical trials that investigated breastfeeding prevalence and/or duration at maternity discharge and/or during first year of life, in term or premature infants. The focus was on studies that have included neonates fed by cup or by bottle during their hospital stay. METHODS: authors examined articles published in English or Portuguese between 1996 and 2006, and included on the Medline, Lilacs and Scielo databases. The following keywords were used: "breastfeeding + bottle feeding" plus "prevalence", "feeding methods", "duration", "low birth weight", "premature" and "neonate". RESULTS: five articles met the inclusion criteria. The number of subjects covered ranged from 14 to 686, amounting to a total of 1552 infants. Cup-feeding for

  4. Synchrotron/crystal sample preparation

    Science.gov (United States)

    Johnson, R. Barry

    1993-01-01

    The Center for Applied Optics (CAO) of the University of Alabama in Huntsville (UAH) prepared this final report entitled 'Synchrotron/Crystal Sample Preparation' in completion of contract NAS8-38609, Delivery Order No. 53. Hughes Danbury Optical Systems (HDOS) is manufacturing the Advanced X-ray Astrophysics Facility (AXAF) mirrors. These thin-walled, grazing incidence, Wolter Type-1 mirrors, varying in diameter from 1.2 to 0.68 meters, must be ground and polished using state-of-the-art techniques in order to prevent undue stress due to damage or the presence of crystals and inclusions. The effect of crystals on the polishing and grinding process must also be understood. This involves coating special samples of Zerodur and measuring the reflectivity of the coatings in a synchrotron system. In order to gain the understanding needed on the effect of the Zerodur crystals by the grinding and polishing process, UAH prepared glass samples by cutting, grinding, etching, and polishing as required to meet specifications for witness bars for synchrotron measurements and for investigations of crystals embedded in Zerodur. UAH then characterized these samples for subsurface damage and surface roughness and figure.

  5. Crystallization of isoelectrically homogeneous cholera toxin

    International Nuclear Information System (INIS)

    Spangler, B.D.; Westbrook, E.M.

    1989-01-01

    Past difficulty in growing good crystals of cholera toxin has prevented the study of the crystal structure of this important protein. The authors have determined that failure of cholera toxin to crystallize well has been due to its heterogeneity. They have now succeeded in overcoming the problem by isolating a single isoelectric variant of this oligomeric protein (one A subunit and five B subunits). Cholera toxin purified by their procedure readily forms large single crystals. The crystal form has been described previously. They have recorded data from native crystals of cholera toxin to 3.0-angstrom resolution with our electronic area detectors. With these data, they have found the orientation of a 5-fold symmetry axis within these crystals, perpendicular to the screw dyad of the crystal. They are now determining the crystal structure of cholera toxin by a combination of multiple heavy-atom isomorphous replacement and density modification techniques, making use of rotational 5-fold averaging of the B subunits

  6. Last crystals for the CMS chandelier

    CERN Multimedia

    2008-01-01

    In March, the last crystals for CMS’s electromagnetic calorimeter arrived from Russia and China. Like dedicated jewellers crafting an immense chandelier, the CMS ECAL collaborators are working extremely hard to install all the crystals before the start-up of the LHC. One of the last CMS end-cap crystals, complete with identification bar code. Lead tungstate crystals mounted onto one section of the CMS ECAL end caps. Nearly 10 years after the first production crystal arrived at CERN in September 1998, the very last shipment has arrived. These final crystals will be used to complete the end-caps of the electromagnetic calorimeter (ECAL) at CMS. All in all, there are more than 75,000 crystals in the ECAL. The huge quantity of CMS lead tungstate crystals used in the ECAL corresponds to the highest volume ever produced for a single experiment. The excellent quality of the crystals, both in ter...

  7. Classificações de enfermagem: mapeamento entre termos do foco da prática Clasificaciones de enfermería: mapeamento entre los términos del foco de la práctica Nursing classification: cross-mapping between focus axis terms

    Directory of Open Access Journals (Sweden)

    Romana Reis da Silva

    2008-12-01

    Full Text Available Devido às mudanças estruturais das classificações: CIPE®beta 2, versão 1.0 e CIPESC®, este estudo descritivo tem como objetivo construir um mapeamento entre os termos do foco da prática, identificando semelhanças e diferenças. A CIPE® 1.0 em relação à beta 2 apresenta: 41% dos termos novos; 33% idênticos; 4% com conceito ampliado; 12% modificados; 8% diferentes; e 2% conceituados apenas na beta 2. A CIPE® 1.0 em relação à CIPESC® apresenta: 79% são novos; 8% idênticos; 1% ampliado; 5% modificados; 4% diferentes; e 3% sem conceito. Houve dificuldades oriundas do processo de tradução e editoração da CIPE® 1.0 e da inexistência de conceitos em alguns termos da CIPESC®. Este trabalho desencadeará um processo de validação dos termos não equivalentes.Debido a los cambios estructurales de las clasificaciones: CIPE® beta-2, versión 1.0 y CIPESC®, este estudio descriptivo tiene como objetivo construir un mapeamiento entre los términos del foco de la práctica, identificando semblenzas y diferencias. La CIPE® 1.0 en relación a beta-2 presenta: 41% de los términos nuevos; 33% idénticos; 4% con el concepto ampliado; 12% modificados; 8% diferentes y 2% conceptuados solamente en la versión beta-2. La CIPE® 1.0 en relación a CIPESC® presenta: 79% son nuevos; 8% idéntico, 1% ampliado; 5% modificados; 4% diferentes y 3% sin concepto. Hubieron dificultades provenientes del proceso brasileiro de traducción y editoración de la CIPE® 1.0 y de la ausencia de algunos conceptos en términos de CIPESC®. Este trabajo va a iniciar un proceso de validación de los términos no equivalentes.Due to structural changes of classifications: ICNP® beta-2, version 1.0 and CIPESC®, this descriptive study aims to identify similarities and differences by building a map between the terms of the focus of practice. The ICNP® 1.0 on the beta-2 shows: 41% are new terms, 33% identical, 4% with expanded concepts, 12% modified; 8

  8. Cálculos neutrônicos, termo-hidráulicos e de segurança de um dispositivo para irradiação de miniplacas (DIM) de elementos conbustíveis tipo dispersão

    OpenAIRE

    Douglas Borges Domingos

    2010-01-01

    Neste trabalho foram desenvolvidos calculos neutrônicos, termo-hidráulicos e de segurança para avaliar a seguranca operacional de um dispositivo de irradiação a ser colocado no núcleo do reator IEA-R1 do IPEN-CNEN/SP. Este dispositivo de irradiação é utilizado para alojar miniplacas de combustvel do tipo dispers~ao de U3O8-Al e U3Si2-Al, com 19,75% em peso de 235U e densidades, respectivamente, de ate 3,2 gU/cm3 e 4,8 gU/cm3. Estas miniplacas serão irradiadas a queimas acima de 50% do 235U, d...

  9. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  10. Channeling and related crystal effects

    International Nuclear Information System (INIS)

    Uggerhoj, Erik

    1995-01-01

    Channeling, the interaction of particles with oriented crystals, has been applied in a wide variety of scientific and technological areas. A workshop at Aarhus, Denmark, this summer highlighted progress and future directions. Radiation emission has been explored and linked to coherent bremsstrahlung and other oriented crystal radiations. Dramatic effects have been found for ultra-relativistic electrons with Lorentz factors of 105 6. Single crystals are unique for investigations of quantum electrodynamics in strong external fields because probabilities for processes in axial/ planar fields are determined by the magnitude of these fields in the particle rest frame. Erik Uggerhoj of Aarhus reported on an extensive series of experiments concerning radiation emission, pair production, and shower formation carried out at CERN by the NA43 collaboration. As Vladimir Baier of Novosibirsk and Yuri Kononets of Kurchatov noted, theoretical treatment of these interconnected radiation distributions is challenging and much work needs to be done. In general, the agreement with the CERN experiments is good, but many areas like polarization phenomena and particle production need investigation. Prominent among high energy applications is extraction from accelerators. At the workshop, Alexei Asseev reported on beam extraction using a bent crystal at Serpukhov. Konrad Elsener and Jukka Klem reviewed recent CERN SPS studies driven by the possibility of using crystals for extraction of LHC beams. Thornton Murphy of Fermilab announced a step in that direction, with a demonstration this summer of extraction from the Tevatron at 900 GeV. Bent crystal channeling is also used for handling extracted high energy beams. Niels Doble presented a beautiful example of a beam for the CERN NA48 CP-violation experiment. Yuri Chesnokov reported that beams had been deflected through angles up to 150 milliradians at Serpukhov

  11. Respostas fisiológicas de recém-nascidos pré-termo submetidos à musicoterapia clássica Respuestas fisiológicas de recién nacidos pretérmino sometidos a musicoterapia clásica Physiological responses of preterm newborn infants submitted to classical music therapy

    Directory of Open Access Journals (Sweden)

    Camila Mendes da Silva

    2013-03-01

    Full Text Available OBJETIVO: Avaliar o efeito da musicoterapia nas respostas fisiológicas de recém-nascidos pré-termo hospitalizados. MÉTODOS: Ensaio clínico não controlado realizado com 12 recém-nascidos pré-termo, com idade gestacional OBJETIVO: Evaluar el efecto de la musicoterapia en las respuestas fisiológicas de recién nacidos pretérmino hospitalizados. MÉTODOS: Ensayo clínico no controlado realizado con 12 recién nacidos pretérmino internados en la Unidad de Terapia Intensiva Neonatal y en la Unidad Intermediaria, con edad gestacional OBJECTIVE: To evaluate the physiological effects of music therapy on hospitalized preterm newborns. METHODS: A noncontrolled clinical trial including 12 newborn infants with gestational age <36 weeks, spontaneously breathing. The preterm infants were submitted to 15-minute sessions of classical music therapy twice a day (morning and afternoon for three consecutive days. The variables: heart and respiratory rates, oxygen saturation, diastolic and systolic arterial pressures, and body temperature were analyzed before and immediately after each music therapy session. RESULTS: There was a decrease in the heart rate after the second session of music therapy (paired t-test; p=0.002, and an increase at the end of the third session (paired t-test; p=0.005. Respiratory rate decreased during the fourth and fifth sessions (paired t-test; p=0.01 and 0.03, respectively. Regarding oxygen saturation, there was an increase after the fifth session (p=0.008. Comparison of physiological parameters among sessions, for the six studied sessions, showed only that the gain in oxygen saturation during the fifth session was significantly higher than during the sixth one (Tukey's test after variance analysis; p=0.04. CONCLUSIONS: Music therapy may modify short-term physiological responses of hospitalized preterm newborn infants.

  12. Importância da avaliação dos movimentos generalizados espontâneos no prognóstico neurológico de recém-nascidos pré-termo The role of spontaneous general movement assessment in the neurological outcome of cerebral lesions in preterm infants

    Directory of Open Access Journals (Sweden)

    Juliana M. Garcia

    2004-08-01

    Full Text Available OBJETIVO: Estudar a relação entre a qualidade, tipos e trajetória dos movimentos generalizados espontâneos em recém-nascidos pré-termo com os achados da ultra-sonografia de crânio neonatal e com a evolução neurológica. MÉTODO: 40 recém-nascidos pré-termo, com idade gestacional OBJECTIVE: To study the relationship among the quality, type, and trajectory of general movements in preterm infants and neonatal cranial ultrasonography findings and neurological outcome. METHOD: Forty preterm newborn infants, with gestational ages under 35 weeks, had their general movements recorded through video-tape during the preterm, term (37th - 42nd postconceptional weeks of age and post-term (49th - 56th postconceptional weeks of age periods, and were prospectively followed up to one-year conceptional age. RESULTS: Our results showed that the quality of general movements, particularly in the post-term period (p = 0.009, were related with the presence of severe cerebral lesions in the neonatal cranial ultrasonography and the neurological outcome. While the presence of severe ultrasonography lesions was associated with an adverse neurological outcome (p = 0.01, the finding of normal general movements patterns was associated with a normal neurological outcome, with negative predictive values of 100%, for the preterm, and 80%, for both term and post-term periods. CONCLUSIONS: When concurrently used, these evaluation methods may increase the specificity and sensitivity in detecting the group of preterm infants at high-risk for neurological disturbances in long-term follow-up.

  13. Modelagem e Simulação da Polimerização Termo e Foto-Iniciada de Resinas Di-Carbonato Di-Alila do Etileno Glicol para a Produção de Lentes Oftálmicas

    Directory of Open Access Journals (Sweden)

    Brogna Fábio M. S.

    2002-01-01

    Full Text Available O polímero termofixo conhecido comercialmente como CR-39 é amplamente utilizado em aplicações ópticas. No processo convencional, utilizam-se peróxidos orgânicos como termo-iniciadores da polimerização. Devido à natureza altamente exotérmica da reação de polimerização, esse processo deve ser conduzido em baixas temperaturas e ocorre lentamente para se evitar defeitos, especialmente no caso de se produzir lentes mais espessas. A utilização de foto-iniciação com ultravioleta, por exemplo, permite uma polimerização mais rápida e reduz os efeitos exotérmicos da reação; por outro lado, a alta taxa de reação e a rápida liberação de calor podem causar defeitos nas lentes. O conhecimento dos perfis de temperatura e de conversão dentro do material durante a polimerização é essencial para se otimizar os processos, tanto termo quanto foto-iniciado. Neste trabalho são estudados modelos para simular esses processos. Os balanços de massa e de energia resultam em equações diferenciais parciais que são resolvidas através do método da Colocação Ortogonal e do método de Runge-Kutta-Gill.

  14. Crystal study and econometric model

    Science.gov (United States)

    1975-01-01

    An econometric model was developed that can be used to predict demand and supply figures for crystals over a time horizon roughly concurrent with that of NASA's Space Shuttle Program - that is, 1975 through 1990. The model includes an equation to predict the impact on investment in the crystal-growing industry. Actually, two models are presented. The first is a theoretical model which follows rather strictly the standard theoretical economic concepts involved in supply and demand analysis, and a modified version of the model was developed which, though not quite as theoretically sound, was testable utilizing existing data sources.

  15. Metadynamics studies of crystal nucleation

    Science.gov (United States)

    Giberti, Federico; Salvalaglio, Matteo; Parrinello, Michele

    2015-01-01

    Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation. PMID:25866662

  16. Metadynamics studies of crystal nucleation

    Directory of Open Access Journals (Sweden)

    Federico Giberti

    2015-03-01

    Full Text Available Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation.

  17. Crystallization inhibitors for amorphous oxides

    International Nuclear Information System (INIS)

    Reznitskij, L.A.; Filippova, S.E.

    1993-01-01

    Data for the last 10 years, in which experimental results of studying the temperature stabilization of x-ray amorphous oxides (including R 3 Fe 5 O 12 R-rare earths, ZrO 2 , In 2 O 3 , Sc 2 O 3 ) and their solid solution are presented, are generalized. Processes of amorphous oxide crystallization with the production of simple oxides, solid solutions and chemical compounds with different polyhedral structure, are investigated. Energy and crystallochemical criteria for selecting the doping inhibitor-components stabilizing the amorphous state are ascertained, temperatures and enthalpies of amorpous oxide crystallization are determined, examination of certain provisions of iso,orphous miscibility theory is conducted

  18. Fundamentals of liquid crystal devices

    CERN Document Server

    Yang, Deng-Ke

    2014-01-01

    Revised throughout to cover the latest developments in the fast moving area of display technology, this 2nd edition of Fundamentals of Liquid Crystal Devices, will continue to be a valuable resource for those wishing to understand the operation of liquid crystal displays. Significant updates include new material on display components, 3D LCDs and blue-phase displays which is one of the most promising new technologies within the field of displays and it is expected that this new LC-technology will reduce the response time and the number of optical components of LC-modules. Prof. Yang is a pion

  19. Liquid Crystals for Nondestructive Evaluation

    Science.gov (United States)

    1978-09-01

    polarizers (e.g., where p is the distance of alignment or pitch, X is the Nicol, Rochon, and Wollaston prisms ) are based upon peak wavelength of scattered...RANGE OF so 45" 45 - EVENT SEVENT T(°C) TEMPERATUJRE TC)4"TEMPERATURE 40RANGE OF T(°) 0-RANGE OF 40LIQUID ’ ൫" CRYSTAL S 36 3S. 30 0 IS 90 180 - I...Temperatures TI > T2 > - > TS defects was possible using the liquid crystal. are the Average TemperatursI Thes Resptivegi. Kapfer , Burns, Salvo, and Doyle

  20. Lattice dynamics of ionic crystals

    International Nuclear Information System (INIS)

    Mahan, G.D.

    1990-01-01

    The theory of lattice dynamics for ionic and rare-gas crystals is derived in the harmonic approximation. We start from a Hamiltonian and average over electron coordinates in order to obtain an effective interaction between ion displacements. We assume that electronic excitations are localized on a single ion, which limits the theory to ionic crystals. The deformation-dipole model and the indirect-ionic-interaction model are derived. These two contributions are closely linked, and together provide an accurate description of short-range forces

  1. Functional possibilities of nonlinear crystals for frequency conversion: uniaxial crystals

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, Yu M [Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Arapov, Yu D; Kasyanov, I V [E.I. Zababakhin All-Russian Scientific-Research Institute of Technical Physics, Russian Federal Nuclear Centre, Snezhinsk, Chelyabinsk region (Russian Federation); Grechin, S G; Nikolaev, P P [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)

    2016-01-31

    The method and results of the analysis of phase-matching and nonlinear properties for all point groups of symmetry of uniaxial crystals that determine their functional possibilities for solving various problems of nonlinear frequency conversion of laser radiation are presented. (nonlinear optical phenomena)

  2. Liquid Crystals in Decorative and Visual Arts

    Science.gov (United States)

    Makow, David

    The following sections are included: * INTRODUCTION * PIGMENT AND STRUCTURAL COLOURS AND THEIR RELEVANCE TO LIQUID CRYSTALS * LIQUID CRYSTAL MATERIALS AND TECHNIQUES FOR DECORATIVE AND VISUAL ARTS * Free cholesteric liquid crystals (FCLC's) * Encapsulated liquid crystals (ECLC's) * Nonsteroid Chiral nematics * Polymers with liquid crystalline properties (PLCs) * COLOUR PROPERTIES OF CHOLESTERIC LIQUID CRYSTALS (CLC's) * Molecular structure and the mechanism of colour production * Dependence of perceived colours on the angle of illumination and viewing * Dependence of perceived colours on temperature * Additive colour properties * Methods of doubling the peak reflectance of cholesteric liquid crystals * Colour gamut * Colours of superimposed and pigmented coatings * Colours in transmission * ACKNOWLEDGEMENTS * REFERENCES

  3. Introduction to crystal growth and characterization

    CERN Document Server

    Benz, Klaus-Werner

    2014-01-01

    This new textbook provides for the first time a comprehensive treatment of the basics of contemporary crystallography and crystal growth in a single volume. The reader will be familiarized with the concepts for the description of morphological and structural symmetry of crystals. The architecture of crystal structures of selected inorganic and molecular crystals is illustrated. The main crystallographic databases as data sources of crystal structures are described. Nucleation processes, their kinetics and main growth mechanism will be introduced in fundamentals of crystal growth. Some phase d

  4. Lunar Magma Ocean Crystallization: Constraints from Fractional Crystallization Experiments

    Science.gov (United States)

    Rapp, J. F.; Draper, D. S.

    2015-01-01

    The currently accepted paradigm of lunar formation is that of accretion from the ejecta of a giant impact, followed by crystallization of a global scale magma ocean. This model accounts for the formation of the anorthosite highlands crust, which is globally distributed and old, and the formation of the younger mare basalts which are derived from a source region that has experienced plagioclase extraction. Several attempts at modelling the crystallization of such a lunar magma ocean (LMO) have been made, but our ever-increasing knowledge of the lunar samples and surface have raised as many questions as these models have answered. Geodynamic models of lunar accretion suggest that shortly following accretion the bulk of the lunar mass was hot, likely at least above the solidus]. Models of LMO crystallization that assume a deep magma ocean are therefore geodynamically favorable, but they have been difficult to reconcile with a thick plagioclase-rich crust. A refractory element enriched bulk composition, a shallow magma ocean, or a combination of the two have been suggested as a way to produce enough plagioclase to account for the assumed thickness of the crust. Recently however, geophysical data from the GRAIL mission have indicated that the lunar anorthositic crust is not as thick as was initially estimated, which allows for both a deeper magma ocean and a bulk composition more similar to the terrestrial upper mantle. We report on experimental simulations of the fractional crystallization of a deep (approximately 100km) LMO with a terrestrial upper mantle-like (LPUM) bulk composition. Our experimental results will help to define the composition of the lunar crust and mantle cumulates, and allow us to consider important questions such as source regions of the mare basalts and Mg-suite, the role of mantle overturn after magma ocean crystallization and the nature of KREEP

  5. NATO Advanced Research Workshop on Incommensurate Crystals, Liquid Crystals, and Quasi-Crystals

    CERN Document Server

    Clark, N

    1988-01-01

    In this NATO-sponsored Advanced Research Workshop we succeeded in bringing together approximately forty scientists working in the three main areas of structurally incommensurate materials: incommensurate crystals (primarily ferroelectric insulators), incommensurate liquid crystals, and metallic quasi-crystals. Although these three classes of materials are quite distinct, the commonality of the physics of the origin and descrip­ tion of these incommensurate structures is striking and evident in these proceedings. A measure of the success of this conference was the degree to which interaction among the three subgroups occurred; this was facili­ tated by approximately equal amounts of theory and experiment in the papers presented. We thank the University of Colorado for providing pleasant housing and conference facilities at a modest cost, and we are especially grate­ ful to Ann Underwood, who retyped all the manuscripts into camera-ready form. J. F. Scott Boulder, Colorado N. A. Clark v CONTENTS PART I: INCO...

  6. Phenomenon of ''self-cleaning'' of crystals

    International Nuclear Information System (INIS)

    Matveev, O.A.; Arkad'eva, E.N.; Goncharov, L.A.

    1975-01-01

    Crystals of germanium and cadmium telluride have been produced having the characteristics corresponding to the low content of electrically active impurities and crystal defects. The crystals have been grown under conditions of an equilibrium diffusion-concentration interaction of the impurities and crystal defects, with the donor alloying and controlling the acceptors concentration. These crystals have been studied with the help of the mass-spectral analysis, the Hall effect, photoelectroscopy, spectral photoconductivity and losses of collection of a charge from an ionizing particle on gamma-detectors fabricated of the crystals. Herein the doped composition of the crystals has been determined, the concentrations of the shallow and deep acceptors and donors have been measured separately, the life-times of the electrons and holes have been measured, the energetic position and the concentration of the carrier capture levels have been determined. The crystals grown possess all the characteristic features of rather pure crystals. The results of the mass-spectral analysis have shown that in the cadmium telluride crystals the impurities are present within 10 14 to 10 17 cm -3 . Therefore, a deep ''self-refining'' of the crystal takes place, which proceeds by means of deactivation of the electrically active centers with their associating into electrically inactive complexes. Thus a fact of the deep ''self-refining'' of germanium- and cadmium telluride crystals is stated. It is presumed that such a ''self-refining'' can actually proceed practically in all the crystals

  7. Homogeneous crystal nucleation in polymers.

    Science.gov (United States)

    Schick, C; Androsch, R; Schmelzer, J W P

    2017-11-15

    The pathway of crystal nucleation significantly influences the structure and properties of semi-crystalline polymers. Crystal nucleation is normally heterogeneous at low supercooling, and homogeneous at high supercooling, of the polymer melt. Homogeneous nucleation in bulk polymers has been, so far, hardly accessible experimentally, and was even doubted to occur at all. This topical review summarizes experimental findings on homogeneous crystal nucleation in polymers. Recently developed fast scanning calorimetry, with cooling and heating rates up to 10 6 K s -1 , allows for detailed investigations of nucleation near and even below the glass transition temperature, including analysis of nuclei stability. As for other materials, the maximum homogeneous nucleation rate for polymers is located close to the glass transition temperature. In the experiments discussed here, it is shown that polymer nucleation is homogeneous at such temperatures. Homogeneous nucleation in polymers is discussed in the framework of the classical nucleation theory. The majority of our observations are consistent with the theory. The discrepancies may guide further research, particularly experiments to progress theoretical development. Progress in the understanding of homogeneous nucleation is much needed, since most of the modelling approaches dealing with polymer crystallization exclusively consider homogeneous nucleation. This is also the basis for advancing theoretical approaches to the much more complex phenomena governing heterogeneous nucleation.

  8. Photonic-crystal waveguide biosensor

    DEFF Research Database (Denmark)

    Skivesen, Nina; Têtu, Amélie; Kristensen, Martin

    2007-01-01

    A photonic-crystal waveguide sensor is presented for biosensing. The sensor is applied for refractive index measurements and detection of protein-concentrations. Concentrations around 10 μg/ml (0.15μMolar) are measured with excellent signal to noise ratio, and a broad, dynamic refractive index se...

  9. Neutron Transmission through Sapphire Crystals

    DEFF Research Database (Denmark)

    of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Those simulations were part of the effort of validating and improving the newly developed interface between the Monte-Carlo neutron transport code MCNP and the Monte Carlo ray-tracing code McStas....

  10. The isotopic dating of crystals

    International Nuclear Information System (INIS)

    Giuliani, G.; Cheilletz, A.

    1995-01-01

    The first part of this work deals with the answer to the question : why are the crystals dated ? Then, some isotopic dating methods are described : U-Th-Pb, K-Ar, 40 Ar/ 39 Ar, Rb-Sr, Sm-Nd, fission traces, carbon 14 methods. Examples concerning emeralds and diamonds are given. (O.L.). 12 refs., 2 figs

  11. Thermotropic liquid crystals recent advances

    CERN Document Server

    Ramamoorthy, Ayyalusamy

    2007-01-01

    This book covers developments in the field of thermotropic liquid crystals and their functional importance. It also presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these areas. New physical techniques that are powerful in characterizing these materials are discussed.

  12. SYNTHESIS, CRYSTAL STRUCTURE AND MAGNETIC ...

    African Journals Online (AJOL)

    Preferred Customer

    Much of the current effort on such extended hybrid metal organic complexes is ... In this paper, we report the synthesis, single crystal X-ray diffraction analysis and ..... with g = 2.0 (0.37 cm3 mol−1 K), and smoothly increases to a value of 0.45 ...

  13. Crystallization: Key thermodynamic, kinetic and hydrodynamic aspects

    Indian Academy of Sciences (India)

    Crystallization is extensively used in different industrial applications, ... In batch crystallization, a crystalline product with uniform size and shape is desirable, .... y concentration, metastable zone width. C hoi. G. J at. Urbana-Champagne,. USA.

  14. Hybrid colloidal plasmonic-photonic crystals.

    Science.gov (United States)

    Romanov, Sergei G; Korovin, Alexander V; Regensburger, Alois; Peschel, Ulf

    2011-06-17

    We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Determination of crystal water in uranium tetrafluoride

    International Nuclear Information System (INIS)

    Cheng Yingfang

    1991-01-01

    A gravimetric method for measuring crystal water in uranium tetrafluoride is reported. Being convenient, reliable and quick, it can be used as a routine analytical method measure crystal water in uranium tetrafluoride, thorium tetrafluoride etc

  16. Crystal collimator systems for high energy frontier

    CERN Document Server

    AUTHOR|(CDS)2100516; Tikhomirov, Viktor; Lobko, Alexander

    2017-01-01

    Crystalline collimators can potentially considerably improve the cleaning performance of the presently used collimator systems using amorphous collimators. A crystal-based collimation scheme which relies on the channeling particle deflection in bent crystals has been proposed and extensively studied both theoretically and experimentally. However, since the efficiency of particle capture into the channeling regime does not exceed ninety percent, this collimation scheme partly suffers from the same leakage problems as the schemes using amorphous collimators. To improve further the cleaning efficiency of the crystal-based collimation system to meet the requirements of the FCC, we suggest here a double crystal-based collimation scheme, to which the second crystal is introduced to enhance the deflection of the particles escaping the capture to the channeling regime in its first crystal. The application of the effect of multiple volume reflection in one bent crystal and of the same in a sequence of crystals is simu...

  17. Computer modeling of liquid crystals

    International Nuclear Information System (INIS)

    Al-Barwani, M.S.

    1999-01-01

    In this thesis, we investigate several aspects of the behaviour of liquid crystal molecules near interfaces using computer simulation. We briefly discuss experiment, theoretical and computer simulation studies of some of the liquid crystal interfaces. We then describe three essentially independent research topics. The first of these concerns extensive simulations of a liquid crystal formed by long flexible molecules. We examined the bulk behaviour of the model and its structure. Studies of a film of smectic liquid crystal surrounded by vapour were also carried out. Extensive simulations were also done for a long-molecule/short-molecule mixture, studies were then carried out to investigate the liquid-vapour interface of the mixture. Next, we report the results of large scale simulations of soft-spherocylinders of two different lengths. We examined the bulk coexistence of the nematic and isotropic phases of the model. Once the bulk coexistence behaviour was known, properties of the nematic-isotropic interface were investigated. This was done by fitting order parameter and density profiles to appropriate mathematical functions and calculating the biaxial order parameter. We briefly discuss the ordering at the interfaces and make attempts to calculate the surface tension. Finally, in our third project, we study the effects of different surface topographies on creating bistable nematic liquid crystal devices. This was carried out using a model based on the discretisation of the free energy on a lattice. We use simulation to find the lowest energy states and investigate if they are degenerate in energy. We also test our model by studying the Frederiks transition and comparing with analytical and other simulation results. (author)

  18. Reporting with Visual Studio and Crystal Reports

    CERN Document Server

    Elkoush, Mahmoud

    2013-01-01

    A fast-paced, example-based guide to learn how to create a reporting application using Visual Studio and Crystal Reports.""Reporting with Visual Studio and Crystal Reports"" is for developers new to Crystal Reports. It will also prove useful to intermediate users who wish to explore some new techniques in Crystal Reports using Microsoft Visual Studio. Readers are expected to have basic knowledge of C#, Microsoft Visual Studio, and Structured Query Language (SQL).

  19. Crystallization of nodular cast iron with carbides

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-12-01

    Full Text Available In this paper a crystallization process of nodular cast iron with carbides having a different chemical composition have been presented. It have been found, that an increase of molybdenum above 0,30% causes the ledeburutic carbides crystallization after (γ+ graphite eutectic phase crystallization. When Mo content is lower, these carbides crystallize as a pre-eutectic phase. In this article causes of this effect have been given.

  20. Spatial solitons in nonlinear photonic crystals

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2000-01-01

    We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero.......We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero....

  1. Preparation of TiC single crystals

    International Nuclear Information System (INIS)

    Scheerer, B.; Fink, J.; Reichardt, W.

    1975-07-01

    TiC single crystals were prepared by vertical zone melting for measurements of the phonon dispersion by inelastic neutron scattering. The influence of the starting material and of the growing conditions on the growth of the crystal were studied. The crystals were characterized by chemical methods, EMX and neutron diffraction. It was possible to grow single crystals with a volume of up to 0.6 cm 3 and mosaic spread of less then 0.4 0 . (orig.) [de

  2. Framework for the analysis of crystallization operations

    DEFF Research Database (Denmark)

    Meisler, Kresten Troelstrup; Abdul Samad, Noor Asma Fazli Bin; Gernaey, Krist

    Crystallization is often applied in the production of salts and/oractive pharmaceutical ingredients (API), and the crystallization step is an essential part of the manufacturing process for many chemicals-based products.In recent years the monitoring and analysis of crystallization operations has...

  3. Economic analysis of crystal growth in space

    Science.gov (United States)

    Ulrich, D. R.; Chung, A. M.; Yan, C. S.; Mccreight, L. R.

    1972-01-01

    Many advanced electronic technologies and devices for the 1980's are based on sophisticated compound single crystals, i.e. ceramic oxides and compound semiconductors. Space processing of these electronic crystals with maximum perfection, purity, and size is suggested. No ecomonic or technical justification was found for the growth of silicon single crystals for solid state electronic devices in space.

  4. Crystallization Kinetics within a Generic Modelling Framework

    DEFF Research Database (Denmark)

    Meisler, Kresten Troelstrup; von Solms, Nicolas; Gernaey, Krist

    2013-01-01

    An existing generic modelling framework has been expanded with tools for kinetic model analysis. The analysis of kinetics is carried out within the framework where kinetic constitutive models are collected, analysed and utilized for the simulation of crystallization operations. A modelling...... procedure is proposed to gain the information of crystallization operation kinetic model analysis and utilize this for faster evaluation of crystallization operations....

  5. Formation of Piroxicam Polymorphism in Solution Crystallization

    DEFF Research Database (Denmark)

    Bruun Hansen, Thomas; Qu, Haiyan

    2015-01-01

    also explored, and new insights into polymorphic control are documented and discussed. The crystal landscape was mapped for cooling crystallization of piroxicam from acetone/water mixtures (0.5 K/min) and for antisolvent crystallization from acetone with water as the antisolvent. Varying cooling rates...

  6. Approaches to automated protein crystal harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Deller, Marc C., E-mail: mdeller@scripps.edu; Rupp, Bernhard, E-mail: mdeller@scripps.edu

    2014-01-28

    Approaches to automated and robot-assisted harvesting of protein crystals are critically reviewed. While no true turn-key solutions for automation of protein crystal harvesting are currently available, systems incorporating advanced robotics and micro-electromechanical systems represent exciting developments with the potential to revolutionize the way in which protein crystals are harvested.

  7. Co-crystallization as a separation technology: controlling product concentrations by co-crystals

    NARCIS (Netherlands)

    Urbanus, J.; Roelands, C.P.M.; Verdoes, D.; Jansens, P.J.; Horst, J.H. ter

    2010-01-01

    Co-crystallization is known as a product formulation technology, but it can also be used as a tool to solve crystallization problems. Product removal by co-crystallization in fermentations is used as a showcase to demonstrate the potential of co-crystallization as a separation technique. In

  8. Avaliação da medida do comprimento do colo e da ausência do eco glandular endocervical para predição do parto pré-termo Evaluation of risk for preterm delivery by measurement of uterine cervix and cervical gland area

    Directory of Open Access Journals (Sweden)

    Claudio Rodrigues Pires

    2004-04-01

    Full Text Available OBJETIVO: verificar a prevalência do sinal eco glandular endocervical (EGE e o comprimento cervical menor ou igual a 20 mm em gestantes entre a 21ª e a 24ª semana e comparar estes sinais ecográficos como fatores indicadores de parto pré-termo espontâneo. MÉTODOS: estudo prospectivo transversal no qual foram incluídas 361 gestantes da população geral, para realização de exame ultra-sonografico em idade gestacional entre a 21ª a 24ª semana. Os critérios de exclusão do estudo foram malformações müllerianas, gestações múltiplas, malformações fetais, óbito fetal, alterações da quantidade de líquido amniótico, placenta com inserção segmentar, antecedentes de cirurgia no colo uterino (conização, amputação, cerclagem e procedimentos cirúrgicos durante a gestação. Após a realização do exame ultra-sonográfico obstétrico morfológico efetuado por via abdominal, seguiu-se o exame ecográfico por via vaginal para observação de uma faixa hipoecóica ou hiperecóica adjacente ao canal endocervical correpondente às glândulas do epitélio endocervical (EGE e mensuração do comprimento cervical. As variáveis qualitativas são representadas por freqüência absoluta e relativa, ao passo que as variáveis quantitativas, por média, desvio-padrão, mediana e valores mínimo e máximo. A associação entre as variáveis qualitativas foi avaliada pelo teste c² ou teste exato de Fisher. Para cada variável estudada, foi calculado o risco relativo seguido do intervalo com 95% de confiança. A técnica de análise de regressão logística univariada foi utilizada para verificar, entre as variáveis estudadas, quais foram indicativas de parto pré-termo espontâneo. O nível de significância adotado foi de 95% (alfa = 5% e descritivos (p iguais ou inferiores a 0,05 foram considerados significantes. RESULTADOS: a incidência do parto pré-termo espontâneo foi de 5,0%. O comprimento do colo uterino revelou-se igual ou

  9. Goos-Haenchen shift in complex crystals

    Energy Technology Data Exchange (ETDEWEB)

    Longhi, Stefano; Della Valle, Giuseppe; Staliunas, Kestutis [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Departament de Fisica i Enginyeria Nuclear, Instituci Catalana de Recerca i Estudis Avanats (ICREA), Universitat Politcnica de Catalunya, Colom 11, E-08222 Terrassa, Barcelona (Spain)

    2011-10-15

    The Goos-Haenchen (GH) effect for wave scattering from complex PT-symmetric periodic potentials (complex crystals) is theoretically investigated, with specific reference to optical GH shift in photonic crystal slabs with a sinusoidal periodic modulation of both real and imaginary parts of the dielectric constant. The analysis highlights some distinct and rather unique features as compared to the GH shift found in ordinary crystals. In particular, as opposed to GH shift in ordinary crystals, which is large at the band gap edges, in complex crystals the GH shift can be large inside the reflection (amplification) band and becomes extremely large as the PT symmetry-breaking threshold is approached.

  10. Amorphous Phase Mediated Crystallization: Fundamentals of Biomineralization

    Directory of Open Access Journals (Sweden)

    Wenjing Jin

    2018-01-01

    Full Text Available Many biomineralization systems start from transient amorphous precursor phases, but the exact crystallization pathways and mechanisms remain largely unknown. The study of a well-defined biomimetic crystallization system is key for elucidating the possible mechanisms of biomineralization and monitoring the detailed crystallization pathways. In this review, we focus on amorphous phase mediated crystallization (APMC pathways and their crystallization mechanisms in bio- and biomimetic-mineralization systems. The fundamental questions of biomineralization as well as the advantages and limitations of biomimetic model systems are discussed. This review could provide a full landscape of APMC systems for biomineralization and inspire new experiments aimed at some unresolved issues for understanding biomineralization.

  11. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  12. Molecular dynamics of liquid crystals

    Science.gov (United States)

    Sarman, Sten

    1997-02-01

    We derive Green-Kubo relations for the viscosities of a nematic liquid crystal. The derivation is based on the application of a Gaussian constraint algorithm that makes the director angular velocity of a liquid crystal a constant of motion. Setting this velocity equal to zero means that a director-based coordinate system becomes an inertial frame and that the constraint torques do not do any work on the system. The system consequently remains in equilibrium. However, one generates a different equilibrium ensemble. The great advantage of this ensemble is that the Green-Kubo relations for the viscosities become linear combinations of time correlation function integrals, whereas they are complicated rational functions in the conventional canonical ensemble. This facilitates the numerical evaluation of the viscosities by molecular dynamics simulations.

  13. Crystallization method employing microwave radiation

    Energy Technology Data Exchange (ETDEWEB)

    Chu, P; Dwyer, F G; Vartuli, J C

    1992-12-01

    This invention relates to a method of crystallizing materials from aqueous crystallization media. Zeolite materials, both natural and synthetic, have been demonstrated in the past to have catalytic properties for various types of hydrocarbon conversion. Certain zeolitic materials are ordered, porous crystalline metallosilicates having a definite crystalline structure as determined by X-ray diffraction within which there are a number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolite material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of large dimensions, these materials have come to be known as molecular sieves and are utilized in a variety of ways to take advantage of these properties. (author). 3 tabs.

  14. Ionic Liquid Crystals: Versatile Materials.

    Science.gov (United States)

    Goossens, Karel; Lava, Kathleen; Bielawski, Christopher W; Binnemans, Koen

    2016-04-27

    This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.

  15. Modelling of photonic crystal fibres

    DEFF Research Database (Denmark)

    Knudsen, Erik

    2003-01-01

    , as well as a honeycomb bandgap fibre and the first analysis of semi-periodic layered air-hole fibres. Using the modelling framework established as a basis, we provide an analysis of microbend loss, by regarding displacement of a fibre core as a stationary stochastic process, inducing mismatch between......In the presenta ph.d. work a theoretical study of aspects of modelling photonic crystal fibres was carried out. Photonic crystal fibres form a class of optical waveguides where guidance is no longer provided by a difference in refractive index between core and cladding. Instead, guidance...... is provided by an arrangement of air-holes running along the length of the fibre. Depending on the geometry of the fibre, the guiding mechanism may be either arising from the formation of a photonic bandgap in the cladding structure (photonic bandgap fibre), or by an effect resembling total internal...

  16. Crystallization method employing microwave radiation

    International Nuclear Information System (INIS)

    Chu, P.; Dwyer, F.G.; Vartuli, J.C.

    1992-01-01

    This invention relates to a method of crystallizing materials from aqueous crystallization media. Zeolite materials, both natural and synthetic, have been demonstrated in the past to have catalytic properties for various types of hydrocarbon conversion. Certain zeolitic materials are ordered, porous crystalline metallosilicates having a definite crystalline structure as determined by X-ray diffraction within which there are a number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolite material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of large dimensions, these materials have come to be known as molecular sieves and are utilized in a variety of ways to take advantage of these properties. (author). 3 tabs

  17. CMS Industries awarded gold, crystal

    CERN Multimedia

    2006-01-01

    The CMS collaboration honoured 10 of its top suppliers in the seventh annual awards ceremony The representatives of the firms that recieved the CMS Gold and Crystal Awards stand with their awards after the ceremony. The seventh annual CMS Awards ceremony was held on Monday 13 March to recognize the industries that have made substantial contributions to the construction of the collaboration's detector. Nine international firms received Gold Awards, and General Tecnica of Italy received the prestigious Crystal Award. Representatives from the companies attended the ceremony during the plenary session of CMS week. 'The role of CERN, its machines and experiments, beyond particle physics is to push the development of equipment technologies related to high-energy physics,'said CMS Awards Coordinator Domenico Campi. 'All of these industries must go beyond the technologies that are currently available.' Without the involvement of good companies over the years, the construction of the CMS detector wouldn't be possible...

  18. Symmetry of crystals and molecules

    CERN Document Server

    Ladd, Mark

    2014-01-01

    This book successfully combines a thorough treatment of molecular and crystalline symmetry with a simple and informal writing style. By means of familiar examples the author helps to provide the reader with those conceptual tools necessary for the development of a clear understanding of what are often regarded as 'difficult' topics. Christopher Hammond, University of Leeds This book should tell you everything you need to know about crystal and molecular symmetry. Ladd adopts an integrated approach so that the relationships between crystal symmetry, molecular symmetry and features of chemical interest are maintained and reinforced. The theoretical aspects of bonding and symmetry are also well represented, as are symmetry-dependent physical properties and the applications of group theory. The comprehensive coverage will make this book a valuable resource for a broad range of readers.

  19. Crystal structure refinement with SHELXL

    Energy Technology Data Exchange (ETDEWEB)

    Sheldrick, George M., E-mail: gsheldr@shelx.uni-ac.gwdg.de [Department of Structural Chemistry, Georg-August Universität Göttingen, Tammannstraße 4, Göttingen 37077 (Germany)

    2015-01-01

    New features added to the refinement program SHELXL since 2008 are described and explained. The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as ‘a CIF’) containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

  20. Modeling the isochronal crystallization kinetics

    International Nuclear Information System (INIS)

    Sahay, S.S.; Krishnan, Karthik

    2004-01-01

    The classical Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, originally formulated for the isothermal condition, is often used in conjunction with additivity principle for modeling the non-isothermal crystallization kinetics. This approach at times results in significant differences between the model prediction and experimental data. In this article, a modification to this approach has been imposed via an additional functional relationship between the activation energy and heating rate. The methodology has been validated with experimental isochronal crystallization kinetic data in Se 71 Te 20 Sb 9 glass and Ge 20 Te 80 systems. It has been shown that the functional relationship between heating rate and activation energy, ascribed to the reduction in apparent activation energy due to increasing non-isothermality, provides better phenomenological description and therefore improves the prediction capability of the JMAK model under isochronal condition

  1. Crystal potential retrieval in HRTEM

    International Nuclear Information System (INIS)

    Beeching, M.J.; Spargo, A.E.C.

    1993-01-01

    A possible method for obtaining the crystal potential by inversion of the complex wavefield at the exit surface of the specimen, based on reversal of the multi-slice algorithm, is outlined. Results from preliminary testing of the method using computer simulated data are presented and appear promising, although the limits of applicability of the method are yet to be defined. 13 refs., 5 figs

  2. Electron damage in organic crystals

    International Nuclear Information System (INIS)

    Howitt, D.G.; Thomas, G.

    1977-01-01

    The effects of radiation damage in three crystalline organic materials (l-valine, cytosine, copper phthalocyanine) have been investigated by electron microscopy. The degradation of these materials has been found to be consistent with a gradual collapse of their crystal structures brought about by ionization damage to the comprising molecules. It is inferred that the crystallinity of these materials is destroyed by ionizing radiation because the damaged molecules cannot be incorporated into the framework of their original structures. (author)

  3. Optical Magnetometer Incorporating Photonic Crystals

    Science.gov (United States)

    Kulikov, Igor; Florescu, Lucia

    2007-01-01

    According to a proposal, photonic crystals would be used to greatly increase the sensitivities of optical magnetometers that are already regarded as ultrasensitive. The proposal applies, more specifically, to a state-of-the-art type of quantum coherent magnetometer that exploits the electromagnetically-induced-transparency (EIT) method for determining a small change in a magnetic field indirectly via measurement of the shift, induced by that change, in the hyperfine levels of resonant atoms exposed to the field.

  4. Biogenic Crystal and New Materials

    International Nuclear Information System (INIS)

    Bigi, A.; Falini, G.; Gazzano, M.; Roveri, N.; Ripamonti, A.; CNR, Bologna

    1998-01-01

    Organism use inorganic compounds to form inorganic-organic structured composites, with remarkable properties and functions. The target of many laboratory experiments is the natural processes simulation, in order to understand the molecular recognition process between the nucleation sites on the macromolecular matrix and the ions on the growing crystal nuclei. The understanding of biological phenomena opens new routes to the design of new materials or to the improvement of ceramics, polymers, semiconductors and composites [it

  5. Monolayer atomic crystal molecular superlattices

    Science.gov (United States)

    Wang, Chen; He, Qiyuan; Halim, Udayabagya; Liu, Yuanyue; Zhu, Enbo; Lin, Zhaoyang; Xiao, Hai; Duan, Xidong; Feng, Ziying; Cheng, Rui; Weiss, Nathan O.; Ye, Guojun; Huang, Yun-Chiao; Wu, Hao; Cheng, Hung-Chieh; Shakir, Imran; Liao, Lei; Chen, Xianhui; Goddard, William A., III; Huang, Yu; Duan, Xiangfeng

    2018-03-01

    Artificial superlattices, based on van der Waals heterostructures of two-dimensional atomic crystals such as graphene or molybdenum disulfide, offer technological opportunities beyond the reach of existing materials. Typical strategies for creating such artificial superlattices rely on arduous layer-by-layer exfoliation and restacking, with limited yield and reproducibility. The bottom-up approach of using chemical-vapour deposition produces high-quality heterostructures but becomes increasingly difficult for high-order superlattices. The intercalation of selected two-dimensional atomic crystals with alkali metal ions offers an alternative way to superlattice structures, but these usually have poor stability and seriously altered electronic properties. Here we report an electrochemical molecular intercalation approach to a new class of stable superlattices in which monolayer atomic crystals alternate with molecular layers. Using black phosphorus as a model system, we show that intercalation with cetyl-trimethylammonium bromide produces monolayer phosphorene molecular superlattices in which the interlayer distance is more than double that in black phosphorus, effectively isolating the phosphorene monolayers. Electrical transport studies of transistors fabricated from the monolayer phosphorene molecular superlattice show an on/off current ratio exceeding 107, along with excellent mobility and superior stability. We further show that several different two-dimensional atomic crystals, such as molybdenum disulfide and tungsten diselenide, can be intercalated with quaternary ammonium molecules of varying sizes and symmetries to produce a broad class of superlattices with tailored molecular structures, interlayer distances, phase compositions, electronic and optical properties. These studies define a versatile material platform for fundamental studies and potential technological applications.

  6. REVIEW: Optics of globular photonic crystals

    Science.gov (United States)

    Gorelik, V. S.

    2007-05-01

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter ~200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported.

  7. Frequency Doubling Broadband Light in Multiple Crystals

    International Nuclear Information System (INIS)

    Alford, William J.; Smith, Arlee V.

    2000-01-01

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth

  8. Protein-crystal growth experiment (planned)

    Science.gov (United States)

    Fujita, S.; Asano, K.; Hashitani, T.; Kitakohji, T.; Nemoto, H.; Kitamura, S.

    1988-01-01

    To evaluate the effectiveness of a microgravity environment on protein crystal growth, a system was developed using 5 cubic feet Get Away Special payload canister. In the experiment, protein (myoglobin) will be simultaneously crystallized from an aqueous solution in 16 crystallization units using three types of crystallization methods, i.e., batch, vapor diffusion, and free interface diffusion. Each unit has two compartments: one for the protein solution and the other for the ammonium sulfate solution. Compartments are separated by thick acrylic or thin stainless steel plates. Crystallization will be started by sliding out the plates, then will be periodically recorded up to 120 hours by a still camera. The temperature will be passively controlled by a phase transition thermal storage component and recorded in IC memory throughout the experiment. Microgravity environment can then be evaluated for protein crystal growth by comparing crystallization in space with that on Earth.

  9. FDTD simulation for plasma photonic crystals

    International Nuclear Information System (INIS)

    Liu Shaobin; Zhu Chuanxi; Yuan Naichang

    2005-01-01

    Plasma photonic crystals are artificially periodic structures, which are composed of plasmas and dielectric structures (or vacuum). In this paper, the piecewise linear current density recursive convolution (PLCDRC) finite-difference time-domain (FDTD) method is applied to study the plasma photonic crystals and those containing defects. In time-domain, the electromagnetic (EM) propagation process and reflection/transmission electric field of Gauss pulses passing through the plasma photonic crystals are investigated. In frequency-domain, the reflection and transmission coefficients of the pulses through the two kinds of crystals are computed. The results illustrate that the plasma photonic crystals mostly reflect for the EM wave of frequencies less than the plasma frequency, and mostly transmit for EM wave of frequencies higher than the plasma frequency. In high frequency domain, the plasma photonic crystals have photonic band gaps, which is analogous to the conventional photonic crystals. (authors)

  10. Numerical simulation of distorted crystal Darwin width

    International Nuclear Information System (INIS)

    Wang Li; Xu Zhongmin; Wang Naxiu

    2012-01-01

    A new numerical simulation method according to distorted crystal optical theory was used to predict the direct-cooling crystal monochromator optical properties(crystal Darwin width) in this study. The finite element analysis software was used to calculate the deformed displacements of DCM crystal and to get the local reciprocal lattice vector of distorted crystal. The broadening of direct-cooling crystal Darwin width in meridional direction was estimated at 4.12 μrad. The result agrees well with the experimental data of 5 μrad, while it was 3.89 μrad by traditional calculation method of root mean square (RMS) of the slope error in the center line of footprint. The new method provides important theoretical support for designing and processing of monochromator crystal for synchrotron radiation beamline. (authors)

  11. The dissolution phenomenon of lysozyme crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, C.; Ulrich, J. [Martin Luther University Halle-Wittenberg, Department of Thermal Separation Processes, Centre of Engineering Science, Halle/Saale (Germany)

    2012-02-15

    Dissolution studies on lysozyme crystals were carried out since the observed dissolution pattern look different from non-protein dissolved crystals. The Tetragonal, High Temperature and Low Temperature Orthorhombic morphologies, crystallized using sodium chloride, were chosen and the influence of different pH, salt and protein concentration on their dissolution was investigated. An increase in pH and/or salt concentration can modify the dissolution behaviour. The pattern of the crystals during the dissolution process will, therefore, develop differently. Frequently a skeleton like crystal pattern followed by a falling apart of the crystals is observed. The multi-component character of the lysozyme crystal (protein, water, buffer, salt) as well as ''solvatomorphism'' gives first insights in the phenomena happening in the dissolution process. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The effective crystal field potential

    CERN Document Server

    Mulak, J

    2000-01-01

    As it results from the very nature of things, the spherical symmetry of the surrounding of a site in a crystal lattice or an atom in a molecule can never occur. Therefore, the eigenfunctions and eigenvalues of any bound ion or atom have to differ from those of spherically symmetric respective free ions. In this way, the most simplified concept of the crystal field effect or ligand field effect in the case of individual molecules can be introduced. The conventional notion of the crystal field potential is narrowed to its non-spherical part only through ignoring the dominating spherical part which produces only a uniform energy shift of gravity centres of the free ion terms. It is well understood that the non-spherical part of the effective potential "seen" by open-shell electrons localized on a metal ion plays an essential role in most observed properties. Light adsorption, electron paramagnetic resonance, inelastic neutron scattering and basic characteristics derived from magnetic and thermal measurements, ar...

  13. Large-area photonic crystals

    Science.gov (United States)

    Ruhl, Tilmann; Spahn, Peter; Hellmann, Gotz P.; Winkler, Holger

    2004-09-01

    Materials with a periodically modulated refractive index, with periods on the scale of light wavelengths, are currently attracting much attention because of their unique optical properties which are caused by Bragg scattering of the visible light. In nature, 3d structures of this kind are found in the form of opals in which monodisperse silica spheres with submicron diameters form a face-centered-cubic (fcc) lattice. Artificial opals, with the same colloidal-crystalline fcc structure, have meanwhile been prepared by crystallizing spherical colloidal particles via sedimentation or drying of dispersions. In this report, colloidal crystalline films are introduced that were produced by a novel technique based on shear flow in the melts of specially designed submicroscopic silica-polymer core-shell hybrid spheres: when the melt of these spheres flows between the plates of a press, the spheres crystallize along the plates, layer by layer, and the silica cores assume the hexagonal order corresponding to the (111) plane of the fcc lattice. This process is fast and yields large-area films, thin or thick. To enhance the refractive index contrast in these films, the colloidal crystalline structure was inverted by etching out the silica cores with hydrofluoric acid. This type of an inverse opal, in which the fcc lattice is formed by mesopores, is referred to as a polymer-air photonic crystal.

  14. Hanging drop crystal growth apparatus

    Science.gov (United States)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  15. Crystal growth of various ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Kunkemoeller, Stefan; Braden, Markus [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Nugroho, Agung [Institut Teknologi Bandung (Indonesia)

    2013-07-01

    Ruthenates of the Ruddlesdon-Popper series exhibit a variety of interesting phenomena ranging from unconventional superconductivity to orbitally polarized Mott insulators. Unfortunately the crystal growth of most of these ruthenates is extremely difficult partially due to the high evaporation of ruthenium; this strongly limits the research on these fascinating materials. We have started to grow single crystals of layered and perovskite ruthenates by the travelling floating-zone method using a Canon SC1-MDH mirror furnace. For the layered Ca{sub 2-x}Sr{sub x}RuO{sub 4} series we focused first on the range of concentration where recent My-SR experiments reveal spin-density wave ordering to occur at relatively high temperature and with a sizeable ordered moment. Good quality crystals of Ca{sub 1.5}Sr{sub 0.5}RuO{sub 4} can be obtained, when an excess of 15 percent of ruthenium is added to the initial preparation of the rod and when a high growth speed up to 40mm/h is used. Even slight modifications of the growing conditions result in large amounts of (Sr/Ca)RuO{sub 3} and (Sr/Ca){sub 3}Ru{sub 2}O{sub 7} intergrowth phases. First attempts to grow perovskite and double-layered ruthenates are discussed as well.

  16. Quartz substrate infrared photonic crystal

    Science.gov (United States)

    Ghadiri, Khosrow; Rejeb, Jalel; Vitchev, Vladimir N.

    2003-01-01

    This paper presents the fabrication of a planar photonic crystal (p2c) made of a square array of dielectric rods embedded in air, operating in the infrared spectrum. A quartz substrate is employed instead of the commonly used silicon or column III-V substrate. Our square structure has a normalized cylinder radius-to-pitch ratio of r/a = 0.248 and dielectric material contrast ɛr of 4.5. We choose a Z-cut synthetic quartz for its cut (geometry), and etching properties. Then a particular Z-axis etching process is employed in order to ensure the sharp-edged verticality of the rods and fast etching speed. We also present the computer simulations that allowed the establishment of the photonic band gaps (PBG) of our photonic crystal, as well as the actual measurements. An experimental measurement have been carried out and compared with different simulations. It was found that experimental results are in good agreement with different simulation results. Finally, a frequency selective device for optical communication based on the introduction of impurity sites in the photonic crystal is presented. With our proposed structure Optical System on a Chip (OsoC) with micro-cavity based active devices such as lasers, diodes, modulators, couplers, frequency selective emitters, add-drop filters, detectors, mux/demuxes and polarizers connected by passive waveguide links can be realized.

  17. Crystal collimator systems for high energy frontier

    Science.gov (United States)

    Sytov, A. I.; Tikhomirov, V. V.; Lobko, A. S.

    2017-07-01

    Crystalline collimators can potentially considerably improve the cleaning performance of the presently used collimator systems using amorphous collimators. A crystal-based collimation scheme which relies on the channeling particle deflection in bent crystals has been proposed and extensively studied both theoretically and experimentally. However, since the efficiency of particle capture into the channeling regime does not exceed ninety percent, this collimation scheme partly suffers from the same leakage problems as the schemes using amorphous collimators. To improve further the cleaning efficiency of the crystal-based collimation system to meet the requirements of the FCC, we suggest here a double crystal-based collimation scheme, to which the second crystal is introduced to enhance the deflection of the particles escaping the capture to the channeling regime in its first crystal. The application of the effect of multiple volume reflection in one bent crystal and of the same in a sequence of crystals is simulated and compared for different crystal numbers and materials at the energy of 50 TeV. To enhance also the efficiency of use of the first crystal of the suggested double crystal-based scheme, we propose: the method of increase of the probability of particle capture into the channeling regime at the first crystal passage by means of fabrication of a crystal cut and the method of the amplification of nonchanneled particle deflection through the multiple volume reflection in one bent crystal, accompanying the particle channeling by a skew plane. We simulate both of these methods for the 50 TeV FCC energy.

  18. Avaliação dos fatores associados ao estado nutricional na idade corrigida de termo em recém-nascidos de muito baixo peso Evaluation of the nutritional status at 40 weeks corrected gestational age in a cohort of very low birth weight infants

    Directory of Open Access Journals (Sweden)

    Nicole M. Gianini

    2005-02-01

    Full Text Available OBJETIVO: Avaliar a adequação do peso ao termo em uma coorte de recém-nascidos com peso de nascimento menor que 1.500 g e correlacioná-la a variáveis clínicas e nutricionais. MÉTODOS: Estudo longitudinal onde recém-nascidos de muito baixo peso de oito hospitais (divididos em duas categorias: tipo I - aporte nutricional agressivo; tipo II - outras práticas foram acompanhados prospectivamente de novembro de 1999 a abril de 2000. O estado nutricional foi avaliado pelo escore z, sendo considerado como desnutrição o escore z menor ou igual a -2, segundo a curva do Canadian Perinatal Surveillance System. Os dados foram analisados por meio de regressão linear múltipla e regressão logística. Este estudo foi aprovado pelo Comitê de Ética em Pesquisa. RESULTADOS: 63% da população estudada (126/200 foi classificada como desnutrida ao termo. O peso ao termo apresentou correlação negativa com o tempo de internação, com a idade gestacional ao nascimento, com o tempo para a recuperação do peso de nascimento e com o clinical risk index for babies (p OBJECTIVE: To evaluate the nutritional status at term of a cohort of newborn babies with birth weights of less than 1,500 g and to correlate this with nutritional practices and clinical variables. METHODS: Very low birth weight infants admitted to eight neonatal intensive care units from November 1999 to April 2000 were studied prospectively. The units were defined as Type I if they employed aggressive nutritional support techniques and Type II if other nutritional practices were used. Babies' were defined as malnourished if their z-score for weight was less than or equal to -2 on the Canadian Perinatal Surveillance System growth curves. Data was analyzed using multivariate linear regression and logistic regression. The study was approved by the Committee for Ethics in Research. RESULTS: Sixty-three percent (126/200 of the study population were classed as being malnourished at term. Weight

  19. Suporte informacional como elemento para orientação de pais de pré-termo: um guia para o serviço de acompanhamento do desenvolvimento no primeiro ano de vida Information support as an element for advising parents of preterm infants: a guide for development follow-up services during the first year of life

    Directory of Open Access Journals (Sweden)

    CMS Martinez

    2007-02-01

    Full Text Available INTRODUÇÃO: A literatura aponta o alto risco de distúrbios biológicos e psicossociais aos quais o bebê pré-termo está susceptível, necessitando de atenção diferenciada daquela dada ao bebê a termo. OBJETIVO: Elaborar um guia de orientação e acompanhamento do desenvolvimento no primeiro ano de vida para pais que freqüentam um serviço de acompanhamento do desenvolvimento de bebês. MÉTODO: Os critérios para inclusão dos participantes foram: ser pais de bebê pré-termo de zero a seis meses de idade corrigida que não apresentavam doença neurológica e não necessitaram de intervenção fisioterápica. O presente estudo, de caráter qualitativo, empregou, na etapa de coleta de dados, a observação direta e a entrevista, efetivadas com as mães e profissionais deste serviço de acompanhamento do desenvolvimento de bebês. A elaboração do Guia baseou-se nas análises das observações dos atendimentos no serviço, na freqüência das respostas das entrevistas com profissionais e mães sobre necessidades e dúvidas no manuseio e cuidado com o bebê e a associação com a literatura. RESULTADOS: Obteve-se um guia contendo informações sobre o desenvolvimento do bebê, distribuído nos quatro primeiros trimestres de vida, e o alerta sobre a importância de calcular a idade corrigida para o acompanhamento adequado dos marcos do desenvolvimento. CONCLUSÃO: A utilização deste guia pode ser feita por diferentes profissionais da saúde e por aqueles que desenvolvem atividades educativas para pais.INTRODUCTION: The literature shows that preterm infants are at high risk of biological and psychological disorders and consequently require a higher level of care than is provided for full-term infants. OBJECTIVE: To draw up a guide advising on development follow-up during the first year of life, for parents who attend a child development follow-up service. METHOD: The inclusion criteria were that participants should be parents of preterm

  20. How many low birthweight babies in low- and middle-income countries are preterm? Cuantos de los recién nacidos de bajo peso de países emergentes son pre-término? Quantos dos recém-nascidos de baixo peso de países emergentes são pré-termo?

    Directory of Open Access Journals (Sweden)

    Fernando C Barros

    2011-06-01

    Full Text Available OBJECTIVE: To assess the prevalence of preterm birth among low birthweight babies in low and middle-income countries. METHODS: Major databases (PubMed, LILACS, Google Scholar were searched for studies on the prevalence of term and preterm LBW babies with field work carried out after 1990 in low- and middle-income countries. Regression methods were used to model this proportion according to LBW prevalence levels. RESULTS: According to 47 studies from 27 low- and middle-income countries, approximately half of all LBW babies are preterm rather than one in three as assumed in studies previous to the 1990s. CONCLUSIONS: The estimate of a substantially higher number of LBW preterm babies has important policy implications in view of special health care needs of these infants. As for earlier projections, our findings are limited by the relative lack of population-based studies.OBJETIVO: Estimar la prevalencia de recién nacidos pre-término entre los recién nacidos de bajo peso al nacer de países de renta media o baja. MÉTODOS: En consulta a bases de datos (PubMed, LILACS, Google Scholar fueron procurados estudios sobre la prevalencia de recién nacidos a término y pre-término entre aquellos de bajo peso al nacer conducidos posteriores a 1990 en países emergentes. Modelos de regresión fueron usados para evaluar la proporción de acuerdo con las prevalencias de bajo peso. RESULTADOS: Con base en 47 estudios de 27 países emergentes, aproximadamente la mitad de todos los recién nacidos con bajo peso serían prematuros, y no uno de cada tres, como se estimó en estudios anteriores a la década de 1990. CONCLUSIONES: La estimación de números sustancialmente más altos de prematuros con bajo peso tiene importantes consecuencias en la planificación de salud, ya que tales recién nacidos demandan cuidados especiales. Aún, los resultados son limitados por la falta de estudios poblacionales.OBJETIVO: Estimar a prevalência de recém-nascidos pré-termo

  1. A Test of Macromolecular Crystallization in Microgravity: Large, Well-Ordered Insulin Crystals

    Science.gov (United States)

    Borgstahl, Gloria E. O.; Vahedi-Faridi, Ardeschir; Lovelace, Jeff; Bellamy, Henry D.; Snell, Edward H.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Crystals of insulin grown in microgravity on space shuttle mission STS-95 were extremely well-ordered and unusually large (many > 2 mm). The physical characteristics of six microgravity and six earth-grown crystals were examined by X-ray analysis employing superfine f slicing and unfocused synchrotron radiation. This experimental setup allowed hundreds of reflections to be precisely examined for each crystal in a short period of time. The microgravity crystals were on average 34 times larger, had 7 times lower mosaicity, had 54 times higher reflection peak heights and diffracted to significantly higher resolution than their earth grown counterparts. A single mosaic domain model could account for reflections in microgravity crystals whereas reflections from earth crystals required a model with multiple mosaic domains. This statistically significant and unbiased characterization indicates that the microgravity environment was useful for the improvement of crystal growth and resultant diffraction quality in insulin crystals and may be similarly useful for macromolecular crystals in general.

  2. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  3. Avaliação de sintomas de ansiedade e depressão em mães de neonatos pré-termo durante e após hospitalização em UTI-Neonatal Anxiety and depression symptoms assessment in pre-term neonates' mothers during and after hospitalization in neonatal intensive care unit

    Directory of Open Access Journals (Sweden)

    Flávia Helena Pereira Padovani

    2004-12-01

    Full Text Available OBJETIVO: Identificar sintomas em nível clínico de ansiedade, disforia e depressão em mães de neonatos pré-termo, comparando dois momentos, durante e após a hospitalização do bebê em Unidade de Terapia Intensiva Neonatal (UTIN. MÉTODOS: 43 mães de neonatos pré-termo de muito baixo peso, sem antecedentes psiquiátricos, foram avaliadas através dos Inventários de Ansiedade Traço-Estado e de Depressão de Beck. Foram realizadas duas avaliações, uma durante a hospitalização do bebê e outra após a alta hospitalar. RESULTADOS: Na primeira avaliação, 44% das mães apresentaram sintomas clínicos de ansiedade, disforia e/ou depressão. Após a alta hospitalar do bebê, houve redução significativa do número de mães (26% com esses sintomas clínicos em relação à primeira avaliação (pOBJECTIVE: To identify clinical level of anxiety, dysphoria and depression symptoms of pre-term infants' mothers between two moments, during and after hospitalization in Neonatal Intensive Care Unit (NICU. METHODS: Previously, mothers with psychiatric background were excluded of the study. Forty-three pre-term and very low birthweight infants' mothers were assessed through State-Trait Anxiety Inventory and Beck Depression Inventory. The assessments were done during and after hospitalization, respectively. RESULTS: In the first assessment, 44% mothers showed clinical level in one or more of the emotional symptoms, such as anxiety, dysphoria or depression. After infants' discharge, the number of mothers with clinical level of emotional symptoms decreased significantly (26% in comparison of the first assessment (p<0.008. The anxiety-state level decreased significantly from the first to the second assessment (from 35% to 12%; p<0.006. No difference in depression and dysphoria symptoms between two assessments were found. CONCLUSION:The pre-term infants' mothers presented situational anxiety and required emotional support to cope with the infants

  4. Os efeitos da estimulação sensório motora oral na sucção nutritiva na mamadeira de recém-nascidos pré-termo The sensory-motor-oral stimulation effects on nutritive sucking of preterm infants during bottle feeding

    Directory of Open Access Journals (Sweden)

    Raquel Coube de Carvalho Yamamoto

    2010-04-01

    Full Text Available OBJETIVO: verificar o desempenho da sucção nutritiva, na mamadeira, em recém-nascidos pré-termo submetidos à estimulação sensório-motora-oral. MÉTODOS: pesquisa do tipo ensaio clínico controlado de intervenção. 20 recém-nascidos pré-termo foram distribuídos em grupo estimulado e grupo controle. Estes grupos foram submetidos à avaliação fonoaudiológica em dois diferentes momentos: na liberação da alimentação por via oral; e quando atingiam alimentação plena por via oral num período de 24 horas. As avaliações foram filmadas, e os resultados foram analisados pela pesquisadora. Para análise dos dados utilizou-se o Teste exato de Fishe r e o Teste "T" de Studen t do software estatístico STATA 10.0. Considerou-se p PURPOSE: to check the nutritive sucking performance in preterm infants that underwent sensory-motororal stimulation. METHODS: a controlled clinical trial of intervention was performed in 20 preterm infants divided into experimental and control group. The infants received a speech therapist evaluation in two different times: at the beginning of the oral feeding (first speech therapist evaluation and when they reached full oral feeding (second evaluation. Statistical data analyses used STATA 10 package and they were analyzed for treatment group differences with Fisher's exact Test and Student's unpaired t-test (p<0.05. RESULTS: infants in the experimental group, in the second evaluation, differed statistically in the pressure of strong sucking (p=0.003, presence of the three adaptive reflexes (p=0.001, coordination among sucking, swallowing and breathing (p=0.003, the total time for sucking (p=0.01 and of number of sucking/time (p<0.01. The total number of sucks showed a statistically significant difference (p<0.05 among the evaluations of the control group. No differences were observed among the groups as for sucking rhythm, and prescribed and ingested milk volume. CONCLUSION: in this study, sensory

  5. Desempenho de crianças pré-termo com muito baixo peso e extremo baixo peso segundo o teste Denver-II The performance of pre-term children with very and extreme low weight according to the Denver-II test

    Directory of Open Access Journals (Sweden)

    Lívia de Castro Magalhães

    2011-12-01

    Full Text Available OBJETIVOS: analisar o desempenho de crianças da região metropolitana Belo Horizonte/MG nascidas pré-termo com muito e extremo baixo peso nos itens do teste Denver II. MÉTODOS: as crianças foram selecionadas em um programa de acompanhamento do desenvolvimento de crianças de risco. A amostra incluiu 177 crianças, nas quais o Teste de Denver II foi aplicado nas idades corrigidas de 4, 8, 12, 18 e 24 meses. As respostas foram comparadas (χ2 aos dados da amostra normativa do instrumento. RESULTADOS: crianças pré-termo de muito e extremo baixo peso apresentaram desempenho superior no primeiro ano de vida com desvantagem a partir dos 12 meses em relação à amostra normativa do Denver II. O grupo de extremo baixo peso foi o que apresentou pior desempenho. CONCLUSÕES: houve diferenças no padrão de respostas das crianças examinadas em relação à amostra normativa do Denver II, sendo importante fazer mais estudos acerca da validade do teste para a população brasileira.OBJECTIVES: to evaluate the performance on the Denver II test of preterm children with very and extreme low weight from the Belo Horizonte/MG metropolitan region. METHODS: the children were selected as part of a program to monitor the development of children at risk. The sample included 177 children, to whom the Denver II Test was applied at corrected ages of 4, 8, 12, 18 and 24 months. The responses were compared (χ2 to data from a normative sample. RESULTS: preterm children with very or extremely low weight showed improved performance in the first year of life, although disadvantages began to emerge after twelve months in relation to the normative Denver II sample. The extremely low weight group performed the worst. CONCLUSIONS: there were differences in the pattern of children's responses compared to those of the normative Denver II sample, and it is important to carry out further studies of the validity of this test for the Brazilian population.

  6. The MORPHEUS II protein crystallization screen

    International Nuclear Information System (INIS)

    Gorrec, Fabrice

    2015-01-01

    MORPHEUS II is a 96-condition initial crystallization screen formulated de novo. The screen incorporates reagents selected from the Protein Data Bank to yield crystals that are not observed in traditional conditions. In addition, the formulation facilitates the optimization and cryoprotection of crystals. High-quality macromolecular crystals are a prerequisite for the process of protein structure determination by X-ray diffraction. Unfortunately, the relative yield of diffraction-quality crystals from crystallization experiments is often very low. In this context, innovative crystallization screen formulations are continuously being developed. In the past, MORPHEUS, a screen in which each condition integrates a mix of additives selected from the Protein Data Bank, a cryoprotectant and a buffer system, was developed. Here, MORPHEUS II, a follow-up to the original 96-condition initial screen, is described. Reagents were selected to yield crystals when none might be observed in traditional initial screens. Besides, the screen includes heavy atoms for experimental phasing and small polyols to ensure the cryoprotection of crystals. The suitability of the resulting novel conditions is shown by the crystallization of a broad variety of protein samples and their efficiency is compared with commercially available conditions

  7. The MORPHEUS II protein crystallization screen

    Energy Technology Data Exchange (ETDEWEB)

    Gorrec, Fabrice, E-mail: fgorrec@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom)

    2015-06-27

    MORPHEUS II is a 96-condition initial crystallization screen formulated de novo. The screen incorporates reagents selected from the Protein Data Bank to yield crystals that are not observed in traditional conditions. In addition, the formulation facilitates the optimization and cryoprotection of crystals. High-quality macromolecular crystals are a prerequisite for the process of protein structure determination by X-ray diffraction. Unfortunately, the relative yield of diffraction-quality crystals from crystallization experiments is often very low. In this context, innovative crystallization screen formulations are continuously being developed. In the past, MORPHEUS, a screen in which each condition integrates a mix of additives selected from the Protein Data Bank, a cryoprotectant and a buffer system, was developed. Here, MORPHEUS II, a follow-up to the original 96-condition initial screen, is described. Reagents were selected to yield crystals when none might be observed in traditional initial screens. Besides, the screen includes heavy atoms for experimental phasing and small polyols to ensure the cryoprotection of crystals. The suitability of the resulting novel conditions is shown by the crystallization of a broad variety of protein samples and their efficiency is compared with commercially available conditions.

  8. Magnetostriction of Tb-Dy-Fe crystals

    International Nuclear Information System (INIS)

    Mei Wu; Okane, T.; Umeda, T.

    1998-01-01

    left angle 111 right angle -oriented twin free Tb-Dy-Fe single crystals, left angle 112 right angle - and left angle 110 right angle -oriented twinned ''single'' Tb-Dy-Fe crystals were prepared using floating zone melting crystal growth methods. Magnetostrictive performances of the crystals were investigated. Better low-field properties were observed in the left angle 110 right angle twinned crystals than in the left angle 112 right angle crystals. The highest properties were achieved in the left angle 111 right angle twin free single crystals. Even though there were still oxidized particles in the present left angle 111 right angle single crystals, a large magnetostrictive jump of 1700 ppm and a very low saturation magnetic field of 500 Oe were obtained. To understand magnetization and magnetostriction of different Tb-Dy-Fe crystals, theoretical modeling was carried out based on a simplified domain rotation model. Magnetization moment rotation paths of different domains were simulated and hence the resultant magnetostriction was obtained, which could adequately account for the experimental results of different crystals. The limitation of the domain rotation model was also discussed. (orig.)

  9. Crystallization of carbohydrate oxidase from Microdochium nivale

    International Nuclear Information System (INIS)

    Dušková, Jarmila; Dohnálek, Jan; Skálová, Tereza; Østergaard, Lars Henrik; Fuglsang, Claus Crone; Kolenko, Petr; Štěpánková, Andrea; Hašek, Jindřich

    2009-01-01

    Industrially used carbohydrate oxidase was successfully crystallized in several forms, diffraction data suitable for structural analysis were collected. Microdochium nivale carbohydrate oxidase was produced by heterologous recombinant expression in Aspergillus oryzae, purified and crystallized. The enzyme crystallizes with varying crystal morphologies depending on the crystallization conditions. Several different crystal forms were obtained using the hanging-drop vapour-diffusion method, two of which were used for diffraction measurements. Hexagon-shaped crystals (form I) diffracted to 2.66 Å resolution, with unit-cell parameters a = b = 55.7, c = 610.4 Å and apparent space group P6 2 22. Analysis of the data quality showed almost perfect twinning of the crystals. Attempts to solve the structure by molecular replacement did not give satisfactory results. Recently, clusters of rod-shaped crystals (form II) were grown in a solution containing PEG MME 550. These crystals belonged to the monoclinic system C2, with unit-cell parameters a = 132.9, b = 56.6, c = 86.5 Å, β = 95.7°. Data sets were collected to a resolution of 2.4 Å. The structure was solved by the molecular-replacement method. Model refinement is currently in progress

  10. Realisation of a novel crystal bender for a fast double crystal monochromator

    CERN Document Server

    Zaeper, R; Wollmann, R; Luetzenkirchen-Hecht, D; Frahm, R

    2001-01-01

    A novel crystal bender for an X-ray undulator beamline as part of a fast double crystal monochromator development for full EXAFS energy range was characterized. Rocking curves of the monochromator crystal system were recorded under different heat loads and bending forces of the indirectly cooled first Si(1 1 1) crystal. The monochromator development implements new piezo-driven tilt tables with wide angular range to adjust the crystals' Bragg angles and a high pressure actuated bender mechanism for the first crystal.

  11. Phonon manipulation with phononic crystals.

    Energy Technology Data Exchange (ETDEWEB)

    Kim Bongsang; Hopkins, Patrick Edward; Leseman, Zayd C.; Goettler, Drew F.; Su, Mehmet F. (University of New Mexico, Albuquerque, NM); El-Kady, Ihab Fathy; Reinke, Charles M.; Olsson, Roy H., III

    2012-01-01

    In this work, we demonstrated engineered modification of propagation of thermal phonons, i.e. at THz frequencies, using phononic crystals. This work combined theoretical work at Sandia National Laboratories, the University of New Mexico, the University of Colorado Boulder, and Carnegie Mellon University; the MESA fabrication facilities at Sandia; and the microfabrication facilities at UNM to produce world-leading control of phonon propagation in silicon at frequencies up to 3 THz. These efforts culminated in a dramatic reduction in the thermal conductivity of silicon using phononic crystals by a factor of almost 30 as compared with the bulk value, and about 6 as compared with an unpatterned slab of the same thickness. This work represents a revolutionary advance in the engineering of thermoelectric materials for optimal, high-ZT performance. We have demonstrated the significant reduction of the thermal conductivity of silicon using phononic crystal structuring using MEMS-compatible fabrication techniques and in a planar platform that is amenable to integration with typical microelectronic systems. The measured reduction in thermal conductivity as compared to bulk silicon was about a factor of 20 in the cross-plane direction [26], and a factor of 6 in the in-plane direction. Since the electrical conductivity was only reduced by a corresponding factor of about 3 due to the removal of conductive material (i.e., porosity), and the Seebeck coefficient should remain constant as an intrinsic material property, this corresponds to an effective enhancement in ZT by a factor of 2. Given the number of papers in literature devoted to only a small, incremental change in ZT, the ability to boost the ZT of a material by a factor of 2 simply by reducing thermal conductivity is groundbreaking. The results in this work were obtained using silicon, a material that has benefitted from enormous interest in the microelectronics industry and that has a fairly large thermoelectric power

  12. Patterning of Perovskite Single Crystals

    KAUST Repository

    Corzo, Daniel

    2017-06-12

    As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are

  13. Crystal growth and properties of novel organic nonlinear optical crystals of 4-Nitrophenol urea

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, M. Krishna, E-mail: krishnamohan.m@ktr.srmuniv.ac.in; Ponnusamy, S.; Muthamizhchelvan, C.

    2017-07-01

    Single crystals of 4-Nitrophenol urea have been grown from water using slow evaporation technique at constant temperature, with the vision to improve the properties of the crystals. The unit cell parameters of the grown crystals were determined by single crystal and powder X-Ray diffraction. FTIR studies reveals the presence of different vibrational bands. The Optical studies confirmed that the crystal is transparent up to 360 nm .TGA and DSC studies were carried out to understand the thermal behavior of crystals. The SHG studies show the suitability of the crystals for NLO applications. The etching studies were carried out to study the behavior of the crystals under different conditions.These studies reveal that the crystals of 4-Nitrophenol urea are suitable for device applications. - Highlights: • 4-Nitrophenol urea crystals of dimensions 14 mm × 1 mm were grown. • UV–Visible studies indicate the crystal is transparent in the region of 370–800 nm. • Thermal studies show the crystal starts decomposing at 170 °C. • SHG studies indicate that the crystals have NLO efficiency 3.5 times that of KDP.

  14. Carboxylic acids in crystallization of macromolecules: learning from successful crystallization experiments.

    Science.gov (United States)

    Offermann, Lesa R; He, John Z; Mank, Nicholas J; Booth, William T; Chruszcz, Maksymilian

    2014-03-01

    The production of macromolecular crystals suitable for structural analysis is one of the most important and limiting steps in the structure determination process. Often, preliminary crystallization trials are performed using hundreds of empirically selected conditions. Carboxylic acids and/or their salts are one of the most popular components of these empirically derived crystallization conditions. Our findings indicate that almost 40 % of entries deposited to the Protein Data Bank (PDB) reporting crystallization conditions contain at least one carboxylic acid. In order to analyze the role of carboxylic acids in macromolecular crystallization, a large-scale analysis of the successful crystallization experiments reported to the PDB was performed. The PDB is currently the largest source of crystallization data, however it is not easily searchable. These complications are due to a combination of a free text format, which is used to capture information on the crystallization experiments, and the inconsistent naming of chemicals used in crystallization experiments. Despite these difficulties, our approach allows for the extraction of over 47,000 crystallization conditions from the PDB. Initially, the selected conditions were investigated to determine which carboxylic acids or their salts are most often present in crystallization solutions. From this group, selected sets of crystallization conditions were analyzed in detail, assessing parameters such as concentration, pH, and precipitant used. Our findings will lead to the design of new crystallization screens focused around carboxylic acids.

  15. Local fields in ionic crystals

    International Nuclear Information System (INIS)

    Claro, F.

    1981-08-01

    Local fields arising from the electronic distortion in perfect ionic crystals are described in terms of multipolar excitations. Field factors for the alkali halides and chalcogenide ions are found to differ significantly from the Lorentz value of 4π/3, the correction size following an exponential dependence on the difference in ionic radii. Local fields are only slightly modified by these corrections however, and together with the Clausius-Mossotti relation may be regarded as accurate to within 2% if the Lorentz value is adopted. (author)

  16. Electrically controlled liquid crystal fiber

    Science.gov (United States)

    Corella-Madueño, A.; Reyes, J. Adrián

    2006-08-01

    We consider a cylindrical fiber whose core is a liquid crystal (LC) subject to the action of a low frequency field applied parallel to the axis of the cylinder and having initially the escaped configuration. We find the distorted textures of the nematic inside the cylinder by assuming arbitrary anchoring boundary conditions. In the optical limit we calculate the ray trajectories followed by a low intensity beam along the fiber parametrized by a low frequency electric field. Finally, we calculate exactly the spatial dependence of the transverse magnetic modes distribution in the guide, on the electric field, by using a numerical scheme. We summarize our paper and discuss our results.

  17. Crystallography beyond periodic Crystal perfection

    International Nuclear Information System (INIS)

    Estevez-Rams, E.

    2008-01-01

    Full text: The discovery of the quasi-crystals [D. Schechtman et. Al., Phys.] Rev. Lett. [53, 1951-1953 (1984)] made very narrow definition of the crystalline state based on the periodicity of a local arrangement of atoms. Since the definition of this State has been a matter of much controversy [G.R. Desiraju, Nature 423, 485 (2003); S. van Smaalen, IUCR Aperiodic Commission Reports. August 7, 2002; International Union of Crystallography. Report of the Executive Committee for 1991; ACTA Cryst. A48, 922-946 (1992)]. We will make a presentation of the current time of the crystallography in this regard from the conceptual point of view. We show the use of the formalism of algorithmic complexity or Kolmogorov [M. Li and P. Vitanyi, An Introduction to Kolmogorov Complexity and Its Applications (Springer Verlag, Heidelberg, 1993), W.H. Zurek, Phys.] Rev. 40, 4731 (1989); Nature 341, 119-124 (1989)] provides a different perspective on the nature of the Crystallographic order. Infinite crystals can be considered solid with zero algorithmic complexities by atom. Show statistical analysis of inorganic compounds [J.L.C. Daams et al., Atlas of Crystal Structure Types for Intermetallic Phases (ASM International, Ohio, 1991), Fachinformationszentrum/NIST Inorganic Crystal Structure Database, Karlsruhe (2003) icsd.fkf.mpg.de] demonstrating that the minimization of complexity is a trend in the crystalline arrangement. We will then compare the degree of disorder of some typical solids according to their algorithmic complexity. Finally, space diffraction will be studied from this same perspective and will be discussed that zero algorithmic complexities by point in space of diffraction does not necessarily imply the same thing for the Atomic arrangement. The discrete portion of the diffraction pattern is a fingerprint of the underlying order but not the actual existence of long-range order. Experimental results will be showcased [E. Estévez-Rams et al., Physical Review B, 63 (2001

  18. Shock compression of diamond crystal

    OpenAIRE

    Kondo, Ken-ichi; Ahrens, Thomas J.

    1983-01-01

    Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the and crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and th...

  19. Crystal ball data acquisition system

    International Nuclear Information System (INIS)

    Chestnut, R.; Kiesling, C.; Bloom, E.; Bulos, F.; Gaiser, J.; Godfrey, G.; Oreglia, M.; Partridge, R.; Peck, C.; Porter, F.; Aschman, D.; Cavali-Sforza, M.; Coyne, D.; Sadrozinski, H.; Kollmann, W.; Richardson, M.

    1979-01-01

    The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A ''physics pipeline'' allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented

  20. Time Operators and Time Crystals

    OpenAIRE

    Nakatsugawa, K.; Fujii, T.; Saxena, A.; Tanda, S.

    2017-01-01

    We investigate time operators in the context of quantum time crystals in ring systems. We demonstrate that a self-adjoint time operator with a periodic time evolution can be derived for a free particle on a ring system: The conventional Aharonov-Bohm time operator is obtained by taking the infinite-radius limit. We also reveal the relationship between our time operator and a $\\mathcal PT$-symmetric time operator. We find that both time operators indeed describe the periodic time evolution of ...

  1. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexei; Pagnoux, Dominique

    2008-01-01

    Just like the periodical crystalline potential in solid state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as cages for storing, filtering or guiding light at the wavelength scale paves the way to the realization of optical and optoelectronic devices with ultimate properties and dimensions. This will contribute towards meeting the demands for greater miniaturization imposed by the processing of an ever increasing number of data. Photonic Crystals will provide students and researchers from different fields with the theoretical background required for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, ranging from optics to microwaves, where photonic crystals have found application. As such, it aims at building bridges between...

  2. DKDP crystal growth controlled by cooling rate

    Science.gov (United States)

    Xie, Xiaoyi; Qi, Hongji; Shao, Jianda

    2017-08-01

    The performance of deuterated potassium dihydrogen phosphate (DKDP) crystal directly affects beam quality, energy and conversion efficiency in the Inertial Confinement Fusion(ICF)facility, which is related with the initial saturation temperature of solution and the real-time supersaturation during the crystal growth. However, traditional method to measure the saturation temperature is neither efficient nor accurate enough. Besides, the supersaturation is often controlled by experience, which yields the higher error and leads to the instability during the crystal growth. In this paper, DKDP solution with 78% deuteration concentration is crystallized in different temperatures. We study the relation between solubility and temperature of DKDP and fit a theoretical curve with a parabola model. With the model, the measurement of saturation temperature is simplified and the control precision of the cooling rate is improved during the crystal growth, which is beneficial for optimizing the crystal growth process.

  3. Photonic Crystals Towards Nanoscale Photonic Devices

    CERN Document Server

    Lourtioz, Jean-Michel; Berger, Vincent; Gérard, Jean-Michel; Maystre, Daniel; Tchelnokov, Alexis

    2005-01-01

    Just like the periodical crystalline potential in solid-state crystals determines their properties for the conduction of electrons, the periodical structuring of photonic crystals leads to envisioning the possibility of achieving a control of the photon flux in dielectric and metallic materials. The use of photonic crystals as a cage for storing, filtering or guiding light at the wavelength scale thus paves the way to the realisation of optical and optoelectronic devices with ultimate properties and dimensions. This should contribute toward meeting the demands for a greater miniaturisation that the processing of an ever increasing number of data requires. Photonic Crystals intends at providing students and researchers from different fields with the theoretical background needed for modelling photonic crystals and their optical properties, while at the same time presenting the large variety of devices, from optics to microwaves, where photonic crystals have found applications. As such, it aims at building brid...

  4. Thermally stimulated luminescence of KDP activated crystals

    International Nuclear Information System (INIS)

    Tagaeva, B.S.

    2005-01-01

    The aim of this work is the study of recombination luminescence pure and doped by the ions Tl, Se, Pb and Cu of crystals double potassium phosphates (KDP) at irradiation by X-rays. It is established that in the given crystals mechanisms for under-threshold defect formation are realize. The impurity ions results the basic crystal light sum redistribution in the TL peaks. Explanations for some phenomena are given. (author)

  5. Butterfly wing color: A photonic crystal demonstration

    Science.gov (United States)

    Proietti Zaccaria, Remo

    2016-01-01

    We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

  6. Edge rotational magnons in magnonic crystals

    International Nuclear Information System (INIS)

    Lisenkov, Ivan; Kalyabin, Dmitry; Nikitov, Sergey

    2013-01-01

    It is predicted that in 2D magnonic crystals the edge rotational magnons of forward volume magnetostatic spin waves can exist. Under certain conditions, locally bounded magnons may appear within the crystal consisting of the ferromagnetic matrix and periodically inserted magnetic/non-magnetic inclusions. It is also shown that interplay of different resonances in 2D magnonic crystal may provide conditions for spin wave modes existence with negative group velocity

  7. Crystal-field effect in UO2

    International Nuclear Information System (INIS)

    Gajek, Z.; Lahalle, M.P.; Krupa, J.C.; Mulak, J.

    1988-01-01

    Simple ab initio model perturbation calculations of the crystal-field parameters for the U 4+ ion in UO 2 crystals are reported. The crystal-field parameters obtained, B 0 4 = -7130 cm -1 and B 0 6 = 2890 cm -1 , turn out to be much lower in value, particularly the first one, than those usually assumed for this compound. They are found, however, to agree with new spectroscopic data and recent inelastic neutron scattering measurements. (orig.)

  8. Measurements of Protein Crystal Face Growth Rates

    Science.gov (United States)

    Gorti, S.

    2014-01-01

    Protein crystal growth rates will be determined for several hyperthermophile proteins.; The growth rates will be assessed using available theoretical models, including kinetic roughening.; If/when kinetic roughening supersaturations are established, determinations of protein crystal quality over a range of supersaturations will also be assessed.; The results of our ground based effort may well address the existence of a correlation between fundamental growth mechanisms and protein crystal quality.

  9. Atuação fonoaudiológica na estimulação precoce da sucção não-nutritiva em recém-nascidos pré-termo Action of speech therapy on early stimulation of non-nutritive sucking in preterm newborns

    Directory of Open Access Journals (Sweden)

    Larisse Taliane Lira Moura

    2009-01-01

    Full Text Available TEMA: estimulação precoce da sucção não-nutritiva em recém-nascidos pré-termo. PROCEDIMENTOS: análise detalhada de três prontuários de recém-nascidos pré-termos com idade gestacional de 33 semanas que apresentavam apenas dificuldade na sucção, sem patologias associadas. Na análise dos prontuários foram levantados os seguintes dados para comparação: peso ao nascer, total de dias no alto risco, total de dias no médio risco, tônus, peso/ganho, tempo de intervenção fonoaudiológica e alta hospitalar. Os bebês foram atendidos na UTI do Hospital Regional de Taguatinga, em Brasília/DF. RESULTADOS: o primeiro recém-nascido (RN1 passou 19 dias no alto risco, o RN2 passou três dias e o RN3 quatro dias. A estimulação da sucção do RN1 foi mais tardia, pela longa permanência no alto risco, na qual não há a atuação fonoaudiológica. O RN1 teve maior dificuldade para desenvolver seu reflexo de sucção e recebeu alta com auxílio do banco de leite. Os RN2 e RN3 receberam alta realizando sucção eficaz no seio materno sem nenhuma recomendação. CONCLUSÃO: os dados obtidos nessa pesquisa apontam para a eficácia da intervenção fonoaudiológica com relação à estimulação precoce da sucção em recém-nascido pré-termo, estando relacionada com a alta hospitalar e o desenvolvimento global do bebê. A estimulação precoce da fonoaudiologia nos recém-nascidos pré-termos é fundamental para uma alimentação no seio materno eficaz, prazerosa e funcional. Além de proporcionar maior vínculo entre mãe e bebê ainda no âmbito hospitalar, a atuação da fonoaudiologia pode favorecer a diminuição do tempo de internação.BACKGROUND: early stimulation of non-nutritive sucking in preterm newborns. PROCEDURES: review of three charts of preterm newborn infants with gestational age of 33 weeks who had difficulty only in sucking, without associated pathologies. In the analysis of the records, the following data were collected

  10. História de desenvolvimento e comportamento de crianças nascidas pré-termo e baixo peso (< 1.500 g Developmental history and behavior of pre-term and low birth-weight children (<1.500g

    Directory of Open Access Journals (Sweden)

    Ana Emilia Vita Carvalho

    2001-01-01

    Full Text Available O presente estudo comparou a história de desenvolvimento, aprendizagem e comportamento de 20 crianças de 8 a 10 anos nascidas pré-termo The aim of this study is to compare the developmental history, learning and behavior of 20 pre-term and very low birth-weight children (VLB and 20 full- term children at eight- ten years old. Data collection included interviews and the Child Behavioral Scale administered to the mothers and the Raven test to the children. Signs of delay in psychomotor behaviors acquisitions and predominance of the left hand use in the VLB compared to the control group were detected. In the school phase, most of the children of both groups presented average intellectual level and were attending regular schools. In the VLB group there was a significantly higher proportion of school failure than in the control group and there were 20% of children with hearing impairment. Authough both groups had signs of behavior problems, the VLB group showed more respiratory problems, enuresis, school-refuse, agitation, impatience and attachment to the mother than school children from Ribeirão Preto.

  11. Os efeitos da posição canguru em resposta aos procedimentos dolorosos em recém-nascidos pré-termo: uma revisão da literatura Effects of kangaroo care during painful procedures in preterm infants: a review

    Directory of Open Access Journals (Sweden)

    Fernanda de Almeida Maia

    2011-09-01

    Full Text Available Apesar de ser conhecido que recém-nascidos de baixo peso são capazes de vivenciar a dor, muitos procedimentos de rotina ainda são realizados sem o uso de analgésicos farmacológicos ou não farmacológicos. A posição canguru é uma estratégia de baixo custo e pode ser utilizado como medida de escolha no manejo da dor de recém-nascidos pré-termos. Torna-se importante encorajar a prática desse método pelas mães, uma vez que é fácil e pode ser realizado antes e durante procedimentos dolorosos invasivos em unidades neonatais contribuindo para a redução álgicaAlthough low-birth neonates are acknowledged to experience pain, many routine procedures continue to be conducted without proper pharmacological or non-pharmacological analgesia. Kangaroo care is a low-cost strategy that can be used in the preterm newborn. Mothers should be encouraged to use this easy-to-perform method, which is feasible both before and during neonatal units' invasive procedures, therefore contributing to pain reduction

  12. 3D DNA Crystals and Nanotechnology

    Directory of Open Access Journals (Sweden)

    Paul J. Paukstelis

    2016-08-01

    Full Text Available DNA’s molecular recognition properties have made it one of the most widely used biomacromolecular construction materials. The programmed assembly of DNA oligonucleotides has been used to create complex 2D and 3D self-assembled architectures and to guide the assembly of other molecules. The origins of DNA nanotechnology are rooted in the goal of assembling DNA molecules into designed periodic arrays, i.e., crystals. Here, we highlight several DNA crystal structures, the progress made in designing DNA crystals, and look at the current prospects and future directions of DNA crystals in nanotechnology.

  13. Crystal Deflectors for High Energy Ion Beams

    CERN Document Server

    Scandale, W

    2013-01-01

    The motion of charged particles entering a crystal at small angles with respect to a crystalline plane is strongly influenced by the average electric field of the ordered nuclei. For sufficiently small angles the particles can be captured in channeling states, thus performing quasi-harmonic oscillations in the potential well between the crystal planes. Channeled particles in a bent crystal are deflected along the bent planes of the crystal. This provides a powerful method to steer and control particle trajectories that has been investigated and occasionally exploited for some decades already.

  14. Use of Plastic Capillaries for Macromolecular Crystallization

    Science.gov (United States)

    Potter, Rachel R.; Hong, Young-Soo; Ciszak, Ewa M.

    2003-01-01

    Methods of crystallization of biomolecules in plastic capillaries (Nalgene 870 PFA tubing) are presented. These crystallization methods used batch, free-interface liquid- liquid diffusion alone, or a combination with vapor diffusion. Results demonstrated growth of crystals of test proteins such as thaumatin and glucose isomerase, as well as protein studied in our laboratory such dihydrolipoamide dehydrogenase. Once the solutions were loaded in capillaries, they were stored in the tubes in frozen state at cryogenic temperatures until the desired time of activation of crystallization experiments.

  15. Pressure-induced melting of micellar crystal

    DEFF Research Database (Denmark)

    Mortensen, K.; Schwahn, D.; Janssen, S.

    1993-01-01

    that pressure improves the solvent quality of water, thus resulting in decomposition of the micelles and consequent melting of the micellar crystal. The combined pressure and temperature dependence reveals that in spite of the apparent increase of order on the 100 angstrom length scale upon increasing......Aqueous solutions of triblock copolymers of poly(ethylene oxide) and poly(propylene oxide) aggregate at elevated temperatures into micelles which for polymer concentrations greater-than-or-equal-to 20% make a hard sphere crystallization to a cubic micellar crystal. Structural studies show...... temperature (decreasing pressure) the overall entropy increases through the inverted micellar crystallization characteristic....

  16. Crystal modifications and dissolution rate of piroxicam.

    Science.gov (United States)

    Lyn, Lim Yee; Sze, Huan Wen; Rajendran, Adhiyaman; Adinarayana, Gorajana; Dua, Kamal; Garg, Sanjay

    2011-12-01

    Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced both needle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

  17. Controlled nucleation and crystallization of fluorozirconate glasses

    International Nuclear Information System (INIS)

    Frischat, G.H.

    1993-01-01

    Pt, Se, and Ag, respectively, were used as nucleating agents for a ZrF 4 -BaF 4 -YF 3 -AlF 3 glass. Nucleation and crystal growth rates were determined as a function of experimental conditions. In all cases the bulk crystals mainly consist of β-BaZrF6, leading to a relatively coarse-grained microstructure. However, in the case of Ag used as a nucleating agent, the microstructure is bimodal with an additional fine-grained crystal phase. In the cases of Se and Ag the relative crystal fraction could be developed in a controlled way between 0 and 100%

  18. The enigma of cooking salt crystals

    International Nuclear Information System (INIS)

    Nikolskaya, E.

    1987-01-01

    Two Soviet experts, Vladimir Gromov and Valentin Krylov, have discovered an unexpected phenomenon on irradiating cooking salt crystals with electrons. When the crystals are subsequently ground the rate at which they are dissolved increases, but not always. The electrons cause the salt molecules to polarize thus creating an internal electric field. This acts against the double electric layer which is inevitably formed in the part of the solution touching the crystal surface. So, if the permittivity of the solution is much greater than that of the molecules of the crystal, the rate of dissolution is increased, and vice versa. (G.T.H.)

  19. Radiation hardness of undoped BGO crystals

    International Nuclear Information System (INIS)

    Sahu, S.K.; Peng, K.C.; Huang, H.C.; Wang, C.H.; Chang, Y.H.; Hou, W.S.; Ueno, K.; Chou, F.I.; Wei, Y.Y.

    1997-01-01

    We measured the radiation hardness of undoped BGO crystals from two different manufacturers. Such crystals are proposed to be used in a small-angle calorimeter of the BELLE detector of the KEK B-factory. Transparency and scintillation light output of the crystals were monitored to see the effect of radiation damage. The crystals show considerable radiation hardness up to 10.2 Mrad equivalent dose, which is much higher than the maximum expected dosage of 500 krad per year of running at BELLE. (orig.)

  20. Plastic crystal phases of simple water models

    International Nuclear Information System (INIS)

    Aragones, J. L.; Vega, C.

    2009-01-01

    We report the appearance of two plastic crystal phases of water at high pressure and temperature using computer simulations. In one of them the oxygen atoms form a body centered cubic structure (bcc) and in the other they form a face centered cubic structure (fcc). In both cases the water molecules were able to rotate almost freely. We have found that the bcc plastic crystal transformed into a fcc plastic crystal via a Martensitic phase transition when heated at constant pressure. We have performed the characterization and localization in the phase diagram of these plastic crystal phases for the SPC/E, TIP4P, and TIP4P/2005 water potential models. For TIP4P/2005 model free energy calculations were carried out for the bcc plastic crystal and fcc plastic crystal using a new method (which is a slight variation of the Einstein crystal method) proposed for these types of solid. The initial coexistence points for the SPC/E and TIP4P models were obtained using Hamiltonian Gibbs–Duhem integration. For all of these models these two plastic crystal phases appear in the high pressure and temperature region of the phase diagram. It would be of interest to study if such plastic crystal phases do indeed exist for real water. This would shed some light on the question of whether these models can describe satisfactorily the high pressure part of the phase diagram of water, and if not, where and why they fail.

  1. Crystal nucleation in simple and complex fluids.

    Science.gov (United States)

    Oxtoby, David W

    2003-03-15

    The application of density-functional methods from statistical mechanics to the nucleation of crystals from the melt is described. Simple fluids such as metals, with sizes comparable with the range of their attractive forces, are compared with complex fluids such as colloidal suspensions and proteins dissolved in solution. A different mechanism for crystal nucleation is proposed in the latter case, in which density (concentration) changes before periodic crystalline order appears. This leads to a theoretical foundation for empirical observations on the 'crystallization window' in protein crystallization. Comparisons are made with the results of computer simulation via molecular dynamics.

  2. Nanoscopic Manipulation and Imaging of Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Rosenblatt, Charles S. [Case Western Reserve Univ., Cleveland, OH (United States)

    2014-02-04

    This is the final project report. The project’s goals centered on nanoscopic imaging and control of liquid crystals and surfaces. We developed and refined techniques to control liquid crystal orientation at surfaces with resolution as small as 25 nm, we developed an optical imaging technique that we call Optical Nanotomography that allows us to obtain images inside liquid crystal films with resolution of 60 x 60 x 1 nm, and we opened new thrust areas related to chirality and to liquid crystal/colloid composites.

  3. Method of fabricating patterned crystal structures

    KAUST Repository

    Yu, Liyang

    2016-12-15

    A method of manufacturing a patterned crystal structure for includes depositing an amorphous material. The amorphous material is modified such that a first portion of the amorphous thin-film layer has a first height/volume and a second portion of the amorphous thin-film layer has a second height/volume greater than the first portion. The amorphous material is annealed to induce crystallization, wherein crystallization is induced in the second portion first due to the greater height/volume of the second portion relative to the first portion to form patterned crystal structures.

  4. Crystal Clear - New crystals for LHC experiments help to improve PET scanners Exhibition LEPFest 2000

    CERN Multimedia

    2000-01-01

    Better resolution through smaller crystals Better images through higher light yieldHigh efficiency, stability and gain by using avalanche photodiodes and low noise electronics Reduced cost of crystals (1/10) through mass production

  5. Cooling Crystallization of Indomethacin: Effect of Supersaturation, Temperature and Seeding on Polymorphism and Crystal Size Distribution

    DEFF Research Database (Denmark)

    Malwade, Chandrakant Ramkrishna; Qu, Haiyan

    2018-01-01

    In this work, effect of crystallization parameters i.e., supersaturation, seeding, and temperature on polymorphism and crystal size of a non-steroidal anti-inflammatory drug, indomethacin (IMC), was investigated. Firstly, several crystallization solvents (ethanol, methanol, ethyl acetate, acetone...... of IMC from ethanol confirmed that the supersaturation, operating temperature and seeding does affect the polymorphism as well as crystal size distribution of IMC. Fine needle shaped crystals of metastable α-IMC were obtained at 5 °C with high supersaturation even in presence of γ-IMC seeds, while...... rhombic plates like crystals of thermodynamically stable γ-IMC were obtained in remaining experiments. The amount of seed loading only marginally influenced the crystal growth rate and median particle diameter (d50). Particle size analysis of crystals obtained showed bimodal distribution in all...

  6. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

    KAUST Repository

    Saidaminov, Makhsud I.

    2015-07-06

    Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

  7. Crystal growth and magnetic property of YFeO3 crystal

    Indian Academy of Sciences (India)

    2Department of Physics, Shanghai University, Shanghai 200444, China. 3School ... YFeO3 and other rare earth substituted crystals with distorted orthorhombic pervoskite-like struc- .... gen, with rotation rates of 30 rpm for the growing crystal or.

  8. Alignment of crystal orientations of the multi-domain photonic crystals in Parides sesostris wing scales

    Science.gov (United States)

    Yoshioka, S.; Fujita, H.; Kinoshita, S.; Matsuhana, B.

    2014-01-01

    It is known that the wing scales of the emerald-patched cattleheart butterfly, Parides sesostris, contain gyroid-type photonic crystals, which produce a green structural colour. However, the photonic crystal is not a single crystal that spreads over the entire scale, but it is separated into many small domains with different crystal orientations. As a photonic crystal generally has band gaps at different frequencies depending on the direction of light propagation, it seems mysterious that the scale is observed to be uniformly green under an optical microscope despite the multi-domain structure. In this study, we have carefully investigated the structure of the wing scale and discovered that the crystal orientations of different domains are not perfectly random, but there is a preferred crystal orientation that is aligned along the surface normal of the scale. This finding suggests that there is an additional factor during the developmental process of the microstructure that regulates the crystal orientation. PMID:24352678

  9. Advances in nonlinear polymers and inorganic crystals, liquid crystals, and laser media

    International Nuclear Information System (INIS)

    Musikant, S.

    1987-01-01

    These proceedings collect papers on laser materials. Topics include: solid state lasers, fracture mechanics in laser materials, optical second harmonic generation, nonlinear optics, molecular crystals, crystal-phase transformation, and materials for laser fusion reactors

  10. LITERATURE SURVEY FOR FRACTIONAL CRYSTALLIZATION STUDY

    International Nuclear Information System (INIS)

    PERSON, J.C.

    2004-01-01

    The literature survey for the fractional crystallization study of material from tank 241-S-112 is completed, fulfilling the requirements of the Test Plan for Tank 241-S-112 Fractional Crystallization Study (Herting 2003). Crystallization involves the formation of one or more solid phases from a fluid phase or an amorphous solid phase. It is applied extensively in the chemical industry, both as a purification process and a separation process. The main advantage of crystallization over distillation is the production of substances with a very high purity, at a low level of energy consumption, and at relatively mild process conditions. Crystallization is one of the older operations in the chemical industry; therefore, practical experience can usually be used for the design and operation of industrial crystallizers. In addition, advances in the understanding of crystallization kinetics can be useful in the control, design, and scale-up of industrial crystallizers. Research work is currently underway; e.g., the CrysCODE (Crystallizer Control and Design) project, littu://www.aui.tudelft.nl/uroiect/Cn/scode/crvscode.htm, at the Delft University of Technology, with the goal of improving the performance and controllability of industrial crystallizers by means of better control and improved design methodologies. Recent developments in fluid dynamics and reactor technology (e.g., compartment approaches) have led to a better understanding of processes and scale-up phenomena. The ultimate aim of such research is to develop a knowledge-based design frame for optimization of industrial crystallization units. Development work is in progress on a rigorous design analysis model for the description of the crystallization process as a function of the reactor geometry, crystallization kinetics, and operating conditions. One modeling effort is aimed at improving the predictive crystallizer model by implementing a population balance equation that depends on two variables: the size and

  11. Crystals: animal, vegetable or mineral?

    Science.gov (United States)

    Hyde, Stephen T

    2015-08-06

    The morphologies of biological materials, from body shapes to membranes within cells, are typically curvaceous and flexible, in contrast to the angular, facetted shapes of inorganic matter. An alternative dichotomy has it that biomolecules typically assemble into aperiodic structures in vivo, in contrast to inorganic crystals. This paper explores the evolution of our understanding of structures across the spectrum of materials, from living to inanimate, driven by those naive beliefs, with particular focus on the development of crystallography in materials science and biology. The idea that there is a clear distinction between these two classes of matter has waxed and waned in popularity through past centuries. Our current understanding, driven largely by detailed exploration of biomolecular structures at the sub-cellular level initiated by Bernal and Astbury in the 1930s, and more recent explorations of sterile soft matter, makes it clear that this is a false dichotomy. For example, liquid crystals and other soft materials are common to both living and inanimate materials. The older picture of disjoint universes of forms is better understood as a continuum of forms, with significant overlap and common features unifying biological and inorganic matter. In addition to the philosophical relevance of this perspective, there are important ramifications for science. For example, the debates surrounding extra-terrestrial life, the oldest terrestrial fossils and consequent dating of the emergence of life on the Earth rests to some degree on prejudices inferred from the supposed dichotomy between life-forms and the rest.

  12. Photonic Crystals: Physics and Technology

    CERN Document Server

    Sibilia, Concita; Marciniak, Marian; Szoplik, Tomasz

    2008-01-01

    The aim of the work is give an overview of the activity in the field of Photonic Crystal developed in the frame of COST P11 action . The main objective of the COST P11 action was to unify and coordinate national efforts aimed at studying linear and nonlinear optical interactions with Photonic Crystals (PCs), without neglecting an important aspect related to the material research as idea and methods of realizations of 3D PC, together with the development and implementation of measurement techniques for the experimental evaluation of their potential applications in different area, as for example telecommunication with novel optical fibers, lasers, nonlinear multi-functionality, display devices , opto-electronics, sensors. The book contain contributions from authors who gave their lecture at the Cost P11 Training School. Training School was held at the Warsaw University (2007) and National Institute of Telecommunications (May 23), Warsaw. It was attended by 23 students. The focus of the School was on the work of...

  13. 3D DNA Origami Crystals.

    Science.gov (United States)

    Zhang, Tao; Hartl, Caroline; Frank, Kilian; Heuer-Jungemann, Amelie; Fischer, Stefan; Nickels, Philipp C; Nickel, Bert; Liedl, Tim

    2018-05-18

    3D crystals assembled entirely from DNA provide a route to design materials on a molecular level and to arrange guest particles in predefined lattices. This requires design schemes that provide high rigidity and sufficiently large open guest space. A DNA-origami-based "tensegrity triangle" structure that assembles into a 3D rhombohedral crystalline lattice with an open structure in which 90% of the volume is empty space is presented here. Site-specific placement of gold nanoparticles within the lattice demonstrates that these crystals are spacious enough to efficiently host 20 nm particles in a cavity size of 1.83 × 10 5 nm 3 , which would also suffice to accommodate ribosome-sized macromolecules. The accurate assembly of the DNA origami lattice itself, as well as the precise incorporation of gold particles, is validated by electron microscopy and small-angle X-ray scattering experiments. The results show that it is possible to create DNA building blocks that assemble into lattices with customized geometry. Site-specific hosting of nano objects in the optically transparent DNA lattice sets the stage for metamaterial and structural biology applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Atomic crystals resistive switching memory

    International Nuclear Information System (INIS)

    Liu Chunsen; Zhang David Wei; Zhou Peng

    2017-01-01

    Facing the growing data storage and computing demands, a high accessing speed memory with low power and non-volatile character is urgently needed. Resistive access random memory with 4F 2 cell size, switching in sub-nanosecond, cycling endurances of over 10 12 cycles, and information retention exceeding 10 years, is considered as promising next-generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory. (topical reviews)

  15. Tunable bandpass filter based on photonic crystal fiber filled with multiple liquid crystals

    DEFF Research Database (Denmark)

    Scolari, Lara; Tartarini, G.; Borelli, E.

    2007-01-01

    A tunable bandpass filter based on a photonic crystal fiber filled with two different liquid crystals is demonstrated. 130 nm bandwidth tunability is achieved by tuning the temperature from 30degC to 90degC.......A tunable bandpass filter based on a photonic crystal fiber filled with two different liquid crystals is demonstrated. 130 nm bandwidth tunability is achieved by tuning the temperature from 30degC to 90degC....

  16. Systematic Modelling and Crystal Size Distribution Control for Batch Crystallization Processes

    DEFF Research Database (Denmark)

    Abdul Samad, Noor Asma Fazli; Singh, Ravendra; Sin, Gürkan

    Crystallization processes form an important class of separation methods that are frequently used in the chemical, the pharmaceutical and the food industry. The specifications of the crystal product are usually given in terms of crystal size, shape and purity. In order to predict the desired cryst...

  17. Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic...

  18. Crystallization in metglass: growth mechanism of crystals and radiation effects in Fe Ni P B

    International Nuclear Information System (INIS)

    Limoge, Y.; Barbu, A.

    1981-08-01

    Studying crystallization mechanisms and transport properties in amorphous metallic alloys we propose a model for systems wich are displaying eutectoid decomposition. Bringing together self diffusion, electron microscopy and electron irradiation experiments on a Fe Ni P B alloys we have shown that crystallization controlled by interfacial diffusion at the crystal surface can explain all the observed features of the experimental behaviour

  19. Protein crystal growth in low gravity

    Science.gov (United States)

    Feigelson, Robert S.

    1993-01-01

    This Final Technical Report for NASA Grant NAG8-774 covers the period from April 27, 1989 through December 31, 1992. It covers five main topics: fluid flow studies, the influence of growth conditions on the morphology of isocitrate lyase crystals, control of nucleation, the growth of lysozyme by the temperature gradient method and graphoepitaxy of protein crystals. The section on fluid flow discusses the limits of detectability in the Schlieren imaging of fluid flows around protein crystals. The isocitrate lyase study compares crystals grown terrestrially under a variety of conditions with those grown in space. The controlling factor governing the morphology of the crystals is the supersaturation. The lack of flow in the interface between the drop and the atmosphere in microgravity causes protein precipitation in the boundary layer and a lowering of the supersaturation in the drop. This lowered supersaturation leads to improved crystal morphology. Preliminary experiments with lysozyme indicated that localized temperature gradients could be used to nucleate crystals in a controlled manner. An apparatus (thermonucleator) was designed to study the controlled nucleation of protein crystals. This apparatus has been used to nucleate crystals of materials with both normal (ice-water, Rochelle salt and lysozyme) and retrograde (horse serum albumin and alpha chymotrypsinogen A) solubility. These studies have lead to the design of an new apparatus that small and more compatible with use in microgravity. Lysozyme crystals were grown by transporting nutrient from a source (lysozyme powder) to the crystal in a temperature gradient. The influence of path length and cross section on the growth rate was demonstrated. This technique can be combined with the thermonucleator to control both nucleation and growth. Graphoepitaxy utilizes a patterned substrate to orient growing crystals. In this study, silicon substrates with 10 micron grooves were used to grow crystals of catalase

  20. Crystallization and Characterization of Galdieria sulphuraria RUBISCO in Two Crystal Forms: Structural Phase Transition Observed in P21 Crystal Form

    Directory of Open Access Journals (Sweden)

    Boguslaw Stec

    2007-10-01

    Full Text Available We have isolated ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCOfrom the red algae Galdieria Sulphuraria. The protein crystallized in two different crystalforms, the I422 crystal form being obtained from high salt and the P21 crystal form beingobtained from lower concentration of salt and PEG. We report here the crystallization,preliminary stages of structure determination and the detection of the structural phasetransition in the P21 crystal form of G. sulphuraria RUBISCO. This red algae enzymebelongs to the hexadecameric class (L8S8 with an approximate molecular weight 0.6MDa.The phase transition in G. sulphuraria RUBISCO leads from two hexadecamers to a singlehexadecamer per asymmetric unit. The preservation of diffraction power in a phasetransition for such a large macromolecule is rare.

  1. Growth morphologies of crystal surfaces

    Science.gov (United States)

    Xiao, Rong-Fu; Alexander, J. Iwan D.; Rosenberger, Franz

    1991-03-01

    We have expanded our earlier Monte Carlo model [Phys. Rev. A 38, 2447 (1988); J. Crystal Growth 100, 313 (1990)] to three dimensions and included reevaporation after accommodation and growth on dislocation-induced steps. We found again that, for a given set of growth parameters, the critical size, beyond which a crystal cannot retain its macroscopically faceted shape, scales linearly with the mean free path in the vapor. However, the three-dimensional (3D) the systems show increased shape stability compared to corresponding 2D cases. Extrapolation of the model results to mean-free-path conditions used in morphological stability experiments leads to order-of-magnitude agreement of the predicted critical size with experimental findings. The stability region for macroscopically smooth (faceted) surfaces in the parameter space of temperature and supersaturation depends on both the surface and bulk diffusion. While surface diffusion is seen to smooth the growth morphology on the scale of the surface diffusion length, bulk diffusion is always destabilizing. The atomic surface roughness increases with increase in growth temperature and supersaturation. That is, the tendency of surface kinetics anisotropies to stabilize the growth shape is reduced through thermal and kinetic roughening. It is also found that the solid-on-solid assumption, which can be advantageously used at low temperatures and supersaturations, is insufficient to describe the growth dynamics of atomically rough interfaces where bulk diffusion governs the process. For surfaces with an emerging screw dislocation, we find that the spiral growth mechanism dominates at low temperatures and supersaturations. The polygonization of a growth spiral decreases with increasing temperature or supersaturation. When the mean free path in the nutrient is comparable to the lattice constant, the combined effect of bulk and surface diffusion reduces the terrace width of a growth spiral in its center region. At elevated

  2. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-01-01

    -23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating

  3. Confinement stabilises single crystal vaterite rods.

    OpenAIRE

    Schenk, AS; Albarracin, EJ; Kim, YY; Ihli, J; Meldrum, FC

    2014-01-01

    Single-crystals of vaterite, the least-stable anhydrous polymorph of CaCO3, are rare in biogenic and synthetic systems. We here describe the synthesis of high aspect ratio single crystal vaterite rods under additive-free conditions by precipitating CaCO3 within the cylindrical pores of track-etch membranes.

  4. Experimental investigation of 4-dimensional superspace crystals

    International Nuclear Information System (INIS)

    Rasing, T.; Janner, A.

    1983-09-01

    The symmetry of incommensurate crystals can be described by higher dimensional space groups in the so called superspace approach. The basic ideas are explained and used for showing that superspace groups provide an adequate frame for analyzing experimental results on incommensurate crystals

  5. Demonstrations with a Liquid Crystal Shutter

    Science.gov (United States)

    Kraftmakher, Yaakov

    2012-01-01

    The experiments presented show the response of a liquid crystal shutter to applied electric voltages and the delay of the operations. Both properties are important for liquid crystal displays of computers and television sets. Two characteristics of the shutter are determined: (i) the optical transmittance versus applied voltage of various…

  6. Photonic crystal fiber based antibody detection

    DEFF Research Database (Denmark)

    Duval, A; Lhoutellier, M; Jensen, J B

    2004-01-01

    An original approach for detecting labeled antibodies based on strong penetration photonic crystal fibers is introduced. The target antibody is immobilized inside the air-holes of a photonic crystal fiber and the detection is realized by the means of evanescent-wave fluorescence spectroscopy...

  7. Vibrating crystals as possible neutron monochromators

    International Nuclear Information System (INIS)

    Stoica, A.D.; Popovici, M.

    1983-09-01

    The Bragg reflection of neutrons of vibratinq perfect crystals is considered. The additional possibilities offered by the Doppler effect for shaping neutron beams in the k-space are discussed. A simple model for computing the vibrating crystal reflectivity is proposed. (author)

  8. Dispersion properties of photonic crystal fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim

    1998-01-01

    Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...

  9. Electron crystallography of three dimensional protein crystals

    NARCIS (Netherlands)

    Georgieva, Dilyana

    2008-01-01

    This thesis describes an investigation of the potential of electron diffraction for studying three dimensional sub-micro-crystals of proteins and pharmaceuticals. A prerequisite for using electron diffraction for structural studies is the predictable availability of tiny crystals. A method for

  10. Photonic crystals: towards nanoscale photonic devices

    National Research Council Canada - National Science Library

    Lourtioz, J.-M

    2005-01-01

    .... From this point of view, the emergence of photonic bandgap materials and photonic crystals at the end of the 1980s can be seen as a revenge to the benefit this time of optics and electromagnetism. In the same way as the periodicity of solid state crystals determines the energy bands and the conduction properties of electrons, the periodical structur...

  11. A high compression crystal growth system

    International Nuclear Information System (INIS)

    Nieman, H.F.; Walton, A.A.; Powell, B.M.; Dolling, G.

    1980-01-01

    This report describes the construction and operating procedure for a high compression crystal growth system, capable of growing single crystals from the fluid phase over the temperature range of 4.2 K to 300 K, at pressures up to 900 MPa. Some experimental results obtained with the system are given for solid β-nitrogen. (auth)

  12. What makes a crystal structure report valid?

    NARCIS (Netherlands)

    Spek, Anthony L.|info:eu-repo/dai/nl/156517566

    2018-01-01

    Single crystal X-ray crystallography has developed into a unique, highly automated and accessible tool to obtain detailed information on molecular structures. Proper archival makes that referees, readers and users of the results of reported crystal structures no longer need to depend solely on the

  13. SERPUKHOV: Focusing particles by a crystal

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    With several Laboratories having shown how bent crystals can be used to steer particle beams, a team working at the Institute for High Energy Physics (IHEP) at Serpukhov, near Moscow, has shown how these crystals can also be used to focus particle beams

  14. A Genetic Analysis of Crystal Growth

    DEFF Research Database (Denmark)

    Brown, Stanley; Sarikaya, Mehmet; Johnson, E.

    2000-01-01

    The regulation of crystal morphology by proteins is often observed in biology. It is a central feature in the formation of hard tissues such as bones, teeth and mollusc shells. We have developed a genetic system in the bacterium Escherichia coli to study the protein-mediated control of crystal...

  15. Precursors in photonic crystals - art. no. 618218

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.; DeLaRue, RM; Viktorovitch, P; Lopez, C; Midrio, M

    2006-01-01

    We derive the Sommerfeld precursor and present the first calculations for the Brillouin precursor that result from the transmission of a pulse through a photonic crystal. The photonic crystal is modelled by a one-dimensional N-layer medium and the pulse is a generic electromagnetic plane wave packet

  16. TRANSMISSION ION CHANNELING IMAGES OF CRYSTAL DEFECTS

    NARCIS (Netherlands)

    KING, PJC; BREESE, MBH; WILSHAW, PR; SMULDERS, PJM; GRIME, GW

    This paper demonstrates how images of crystal defects can be produced using ion channeling. A focused, scanned beam of MeV protons from the University of Oxford Nuclear Microprobe has been used. With the beam aligned with a channeling direction of the crystal, protons transmitted through the thinned

  17. Application-oriented Crystallization of Pharmaceutical Products

    DEFF Research Database (Denmark)

    Bruun Hansen, Thomas

    The purpose of this PhD thesis is to investigate various options for controlling the crystallization process of pharmaceutical products, both with regards to polymorphic control and crystal morphology. During this process, several model compounds were used, depending on the goal of the studies...

  18. Nanoimprinted polymer photonic crystal dye lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Smith, Cameron; Buss, Thomas

    2010-01-01

    Optically pumped polymer photonic crystal band-edge dye lasers are presented. The photonic crystal is a rectangular lattice providing laser feedback as well as an optical resonance for the pump light. The lasers are defined in a thin film of photodefinable Ormocore hybrid polymer, doped...

  19. Scaling-Up Eutectic Freeze Crystallization

    NARCIS (Netherlands)

    Genceli, F.E.

    2008-01-01

    A novel crystallization technology, Eutectic Freeze Crystallization (EFC) has been investigated and further developed in this thesis work. EFC operates around the eutectic temperature and composition of aqueous solutions and can be used for recovery of (valuable) dissolved salts (and/or or acids)

  20. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre...

  1. Photonic crystal scintillators and methods of manufacture

    Science.gov (United States)

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  2. Hybrid photonic-crystal fiber

    DEFF Research Database (Denmark)

    Markos, Christos; Travers, John C.; Abdolvand, Amir

    2017-01-01

    This article offers an extensive survey of results obtained using hybrid photonic-crystal fibers (PCFs) which constitute one of the most active research fields in contemporary fiber optics. The ability to integrate novel and functional materials in solid- and hollow-core PCFs through various...... is reviewed from scientific and technological perspectives, focusing on how different fluids, solids, and gases can significantly extend the functionality of PCFs. The first part of this review discusses the efforts to develop tunable linear and nonlinear fiber-optic devices using PCFs infiltrated...... with various liquids, glasses, semiconductors, and metals. The second part concentrates on recent and state-of-the-art advances in the field of gas-filled hollow-core PCFs. Extreme ultrafast gas-based nonlinear optics toward light generation in the extreme wavelength regions of vacuum ultraviolet, pulse...

  3. Crystal structure of levomepromazine maleate

    Directory of Open Access Journals (Sweden)

    Gyula Tamás Gál

    2016-05-01

    Full Text Available The asymmetric unit of the title salt, C19H25N2OS+·C4H3O4− [systematic name: (S-3-(2-methoxyphenothiazin-10-yl-N,N,2-trimethylpropanaminium hydrogen maleate], comprises two (S-levomepromazine cations and two hydrogen maleate anions. The conformations of the two cations are similar. The major difference relates to the orientation of the methoxy substituent at the phenothiazine ring system. The crystal components form a three-dimensional supramolecular network via N—H...O, C—H...O and C—H...π interactions. A comparison of the conformations of the levomepromazine cations with those of the neutral molecule and similar protonated molecules reveals significant conformational flexibility of the phenothiazine ring system and the substituent at the phenothiazine N atom.

  4. Grain Interactions in Crystal Plasticity

    International Nuclear Information System (INIS)

    Boyle, K.P.; Curtin, W.A.

    2005-01-01

    The plastic response of a sheet metal is governed by the collective response of the underlying grains. Intragranular plasticity depends on intrinsic variables such as crystallographic orientation and on extrinsic variables such as grain interactions; however, the role of the latter is not well understood. A finite element crystal plasticity formulation is used to investigate the importance of grain interactions on intragranular plastic deformation in initially untextured polycrystalline aggregates. A statistical analysis reveals that grain interactions are of equal (or more) importance for determining the average intragranular deviations from the applied strain as compared to the orientation of the grain itself. Furthermore, the influence of the surrounding grains is found to extend past nearest neighbor interactions. It is concluded that the stochastic nature of the mesoscale environment must be considered for a proper understanding of the plastic response of sheet metals at the grain-scale

  5. Surface states in photonic crystals

    Directory of Open Access Journals (Sweden)

    Vojtíšek P.

    2013-05-01

    Full Text Available Among many unusual and interesting physical properties of photonic crystals (PhC, in recent years, the propagation of surface electromagnetic waves along dielectric PhC boundaries have attracted considerable attention, also in connection to their possible applications. Such surfaces states, produced with the help of specialized defects on PhC boundaries, similarly to surfaces plasmons, are localized surfaces waves and, as such, can be used in various sensing applications. In this contribution, we present our recent studies on numerical modelling of surface states (SS for all three cases of PhC dimensionality. Simulations of these states were carried out by the use of plane wave expansion (PWE method via the MIT MPB package.

  6. Single Crystal Diffuse Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Richard Welberry

    2018-01-01

    Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.

  7. Resonantly scattering crystals and surfaces

    International Nuclear Information System (INIS)

    Gunn, J.M.F.; Mahon, P.J.

    1990-12-01

    We examine coherence effects from forming a crystal of resonant scatterers by generalising the Fano model for autoionising resonances in electron scattering from atoms to a lattice of such scatterers. (We have in mind the case of neutron scattering from nuclei.) We solve this problem to yield two branches to the dispersion relation for the neutron in general and three when the resonance coincides with a Brillouin Zone boundary. The 'width' of the resonance is enhanced over the isolated nucleus, the best candidate for observation being the 2eV 185 Re resonance near the Bragg condition. We use these results to calculate the reflection coefficient from a surface, revealing total external reflection near resonance. We discuss experimental feasibility in both the neutron and electron cases. (author)

  8. Rotons, Superfluidity, and Helium Crystals

    Science.gov (United States)

    Balibar, Sébastien

    2006-09-01

    Fritz London understood that quantum mechanics could show up at the macroscopic level, and, in 1938, he proposed that superfluidity was a consequence of Bose-Einstein condensation. However, Lev Landau never believed in London's ideas; instead, he introduced quasiparticles to explain the thermodynamics of superfluid 4He and a possible mechanism for its critical velocity. One of these quasiparticles, a crucial one, was his famous "roton" which he considered as an elementary vortex. At the LT0 conference (Cambridge, 1946), London criticized Landau and his "theory based on the shaky grounds of imaginary rotons". Despite their rather strong disagreement, Landau was awarded the London prize in 1960, six years after London's death. Today, we know that London and Landau had both found part of the truth: BEC takes place in 4He, and rotons exist. In my early experiments on quantum evaporation, I found direct evidence for the existence of rotons and for evaporation processes in which they play the role of photons in the photoelectric effect. But rotons are now considered as particular phonons which are nearly soft, due to some local order in superfluid 4He. Later we studied helium crystals which are model systems for the general study of crystal surfaces, but also exceptional systems with unique quantum properties. In our recent studies of nucleation, rotons show their importance again: by using acoustic techniques, we have extended the study of liquid 4He up to very high pressures where the liquid state is metastable, and we wish to demonstrate that the vanishing of the roton gap may destroy superfluidity and trigger an instability towards the crystalline state.

  9. Coupled Photonic Crystal Cavity Array Laser

    DEFF Research Database (Denmark)

    Schubert, Martin

    in the quadratic lattice. Processing techniques are developed and optimized in order fabricate photonic crystals membranes in gallium arsenide with quantum dots as gain medium and in indium gallium arsenide phosphide with quantum wells as gain medium. Several key issues in process to ensure good quality....... The results are in good agreement with standard coupled mode theory. Also a novel type of photonic crystal structure is proposed called lambda shifted cavity which is a twodimensional photonic crystal laser analog of a VCSEL laser. Detailed measurements of the coupled modes in the photonic crystals...... with quantum dots are carried out. In agreement with a simple gain model the structures do not show stimulated emission. The spectral splitting due to the coupling between single cavities as well as arrays of cavities is studied theoretically and experimentally. Lasing is observed for photonic crystal cavity...

  10. Crystallization dynamics in glass-forming systems

    Energy Technology Data Exchange (ETDEWEB)

    Cullinan, Timothy Edward [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    Crystallization under far-from-equilibrium conditions is investigated for two different scenarios: crystallization of the metallic glass alloy Cu50Zr50 and solidification of a transparent organic compound, o-terphenyl. For Cu50Zr50, crystallization kinetics are quanti ed through a new procedure that directly fits thermal analysis data to the commonly utilized JMAK model. The phase evolution during crystallization is quantified through in-situ measurements (HEXRD, DSC) and ex-situ microstructural analysis (TEM, HRTEM). The influence of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined. For o-terphenyl, the relationship between crystal growth velocity and interface undercooling is systematically studied via directional solidification.

  11. An Overview of Biological Macromolecule Crystallization

    Directory of Open Access Journals (Sweden)

    Irene Russo Krauss

    2013-05-01

    Full Text Available The elucidation of the three dimensional structure of biological macromolecules has provided an important contribution to our current understanding of many basic mechanisms involved in life processes. This enormous impact largely results from the ability of X-ray crystallography to provide accurate structural details at atomic resolution that are a prerequisite for a deeper insight on the way in which bio-macromolecules interact with each other to build up supramolecular nano-machines capable of performing specialized biological functions. With the advent of high-energy synchrotron sources and the development of sophisticated software to solve X-ray and neutron crystal structures of large molecules, the crystallization step has become even more the bottleneck of a successful structure determination. This review introduces the general aspects of protein crystallization, summarizes conventional and innovative crystallization methods and focuses on the new strategies utilized to improve the success rate of experiments and increase crystal diffraction quality.

  12. Theory of fluorescence in photonic crystals

    International Nuclear Information System (INIS)

    Vats, Nipun; John, Sajeev; Busch, Kurt

    2002-01-01

    We present a formalism for the description of fluorescence from optically active materials embedded in a photonic crystal structure possessing a photonic band gap or pseudogap. An electromagnetic field expansion in terms of Bloch modes of the crystal is used to develop the equations for fluorescence in terms of the local density of photon modes available to the emitting atoms in either the high or low dielectric regions of the crystal. We then obtain expressions for fluorescence spectra and emission dynamics for luminescent materials in photonic crystals. The validity of our formalism is demonstrated through the calculation of relevant quantities for model photon densities of states. The connection of our calculations to the description of realistic systems is discussed. We also describe the consequences of these analyses on the accurate description of the interaction between radiative systems and the electromagnetic reservoir within photonic crystals

  13. Photonic crystals physics, fabrication and applications

    CERN Document Server

    Ohtaka, Kazuo

    2004-01-01

    "Photonic Crystals" details recent progress in the study of photonic crystals, ranging from fundamental aspects to up-to-date applications, in one unified treatment It covers most of the worldwide frontier fields in photonic crystals, including up-to-date fabrication techniques, recent and future technological applications, and our basic understanding of the various optical properties of photonic crystals Brand-new theoretical and experimental data are also presented The book is intended for graduate course students and specialists actively working in this field, but it will also be useful for newcomers, especially the extensive chapter dealing with fundamental aspects of photonic crystals, which paves the way to a full appreciation of the other topics addressed

  14. Monolithic I-Beam Crystal Monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Bagnasco, John

    2001-10-16

    Curved crystal, focusing monochromators featuring cubed-root thickness profiles typically employ side-clamped cooling to reduce thermally induced overall bend deformation of the crystal. While performance is improved, residual bend deformation is often an important limiting factor in the monochromator performance. A slightly asymmetric ``I-beam'' crystal cross section with cubed-root flange profiles has been developed to further reduce this effect. Physical motivation, finite-element modeling evaluation and performance characteristics of this design are discussed. Reduction of high mounting stress at the fixed end of the crystal required the soldering of an Invar support fixture to the crystal. Detailed descriptions of this process along with its performance characteristics are also presented.

  15. Co-Crystal Screening of Diclofenac

    Directory of Open Access Journals (Sweden)

    John Desper

    2011-08-01

    Full Text Available In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac—an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined—a range of pyrazoles, pyridines, and pyrimidines were screened for co-crystal formation using solvent assisted grinding and infrared spectroscopy with an overall success rate of 50%. The crystal structures of three new diclofenac co-crystals are reported herein: (diclofenac∙(2-aminopyrimidine, (diclofenac∙(2-amino-4,6-dimethylpyrimidine, and (diclofenac∙(2-amino-4-chloro-6-methylpyrimidine.

  16. Co-crystal screening of diclofenac.

    Science.gov (United States)

    Aakeröy, Christer B; Grommet, Angela B; Desper, John

    2011-08-31

    In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API) without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac-an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined-a range of pyrazoles, pyridines, and pyrimidines were screened for co-crystal formation using solvent assisted grinding and infrared spectroscopy with an overall success rate of 50%. The crystal structures of three new diclofenac co-crystals are reported herein: (diclofenac)∙(2-aminopyrimidine), (diclofenac)∙(2-amino-4,6-dimethylpyrimidine), and (diclofenac)∙(2-amino-4-chloro-6-methylpyrimidine).

  17. Crystallization of Ulex europaeus lectin I.

    Science.gov (United States)

    Vandonselaar, M; Delbaere, L T

    1994-10-21

    The lectin I from Ulex europaeus (UEAI) has a strong affinity for the H-type 2 human blood group determinant. Single crystals of UEAI have been grown in the monoclinic crystal system. Initial crystals were obtained after 11 months from a solution of 10 mg/ml protein, 40% 2,4-methylpentanediol and 0.1 N acetate buffer at pH 5.2. The technique of washing and reseeding was used to generate large suitable crystals. The space group is C2 with a = 78.84 A, b = 69.85 A, c = 120.62 A, beta = 108.74 degrees and Z = 4; there is one molecular dimer per asymmetric unit and the solvent content is estimated to be 58%. The crystals diffract to at least 2.8 A d spacings and are stable in the X-ray beam for more than three days.

  18. Crystal shapes on striped surface domains

    International Nuclear Information System (INIS)

    Valencia, Antoni

    2004-01-01

    The equilibrium shapes of a simple cubic crystal in contact with a planar chemically patterned substrate are studied theoretically using an effective interface model. The substrate is primarily made of lyophobic material and is patterned with a lyophilic (easily wettable) stripe domain. Three regimes can be distinguished for the equilibrium shapes of the crystal. The transitions between these regimes as the volume of the crystal is changed are continuous or discontinuous depending on the strength of the couplings between the crystal and the lyophilic and lyophobic surface domains. If the crystal grows through a series of states close to equilibrium, the discontinuous transitions correspond to growth instabilities. These transitions are compared with similar results that have been obtained for a volume of liquid wetting a lyophilic stripe domain

  19. Rapid Crystallization of the Bishop Magma

    Science.gov (United States)

    Gualda, G. A.; Anderson, A. T.; Sutton, S. R.

    2007-12-01

    Substantial effort has been made to understand the longevity of rhyolitic magmas, and particular attention has been paid to the systems in the Long Valley area (California). Recent geochronological data suggest discrete magma bodies that existed for hundreds of thousands of years. Zircon crystallization ages for the Bishop Tuff span 100-200 ka, and were interpreted to reflect slow crystallization of a liquid-rich magma. Here we use the diffusional relaxation of Ti zoning in quartz to investigate the longevity of the Bishop magma. We have used such an approach to show the short timescales of crystallization of Ti-rich rims on quartz from early- erupted Bishop Tuff. We have now recognized Ti-rich cores in quartz that can be used to derive the timescales of their crystallization. We studied four samples of the early-erupted Bishop. Hand-picked crystals were mounted on glass slides and polished. Cathodoluminescence (CL) images were obtained using the electron microprobe at the University of Chicago. Ti zoning was documented using the GeoSoilEnviroCARS x-ray microprobe at the Advanced Photon Source (Argonne National Lab). Quartz crystals in all 4 samples include up to 3 Ti-bearing zones: a central core (50-100 μm in diameter, ca. 50 ppm Ti), a volumetrically predominant interior (~40 ppm Ti), and in some crystals a 50-100 μm thick rim (50 ppm Ti). Maximum estimates of core residence times were calculated using a 1D diffusion model, as the time needed to smooth an infinitely steep profile to fit the observed profile. Surprisingly, even for the largest crystals studied - ca. 2 mm in diameter - core residence times are less than 1 ka. Calculated growth rates imply that even cm-sized crystals crystallized in less than 10 ka. Crystal size distribution data show that crystals larger than 3 mm are exceedingly rare, such that the important inference is that the bulk of the crystallization of the early-erupted Bishop magma occurred in only a few thousand years. This timescale

  20. Innovation in crystal growth: A personal perspective

    Science.gov (United States)

    Mullin, J. B.

    2008-04-01

    The evolution of crystal growth has been crucially dependent on revolutionary innovations and initiatives involving ideas, technology and communication. A personal perspective is presented on some of these aspects in connection with the early history of semiconductors that have helped evolve our knowledge and advance the science and technology of crystal growth. The presentation considers examples from work on germanium, silicon, indium antimonide, gallium arsenide, indium phosphide, gallium phosphide and mercury cadmium telluride. In connection with metal organic vapour phase epitaxy (MOVPE), the influence of adduct purification for alkyls is noted together with the growth of Hg xCd 1-xTe. The role of crystal growth organisations together with initiatives in the publication of the Journal of Crystal Growth (JCG) and the pivotal role of the International Organisation of Crystal Growth (IOCG) are also highlighted in the quest for scientific excellence.

  1. Single Crystals Grown Under Unconstrained Conditions

    Science.gov (United States)

    Sunagawa, Ichiro

    Based on detailed investigations on morphology (evolution and variation in external forms), surface microtopography of crystal faces (spirals and etch figures), internal morphology (growth sectors, growth banding and associated impurity partitioning) and perfection (dislocations and other lattice defects) in single crystals, we can deduce how and by what mechanism the crystal grew and experienced fluctuation in growth parameters through its growth and post-growth history under unconstrained condition. The information is useful not only in finding appropriate way to growing highly perfect and homogeneous single crystals, but also in deciphering letters sent from the depth of the Earth and the Space. It is also useful in discriminating synthetic from natural gemstones. In this chapter, available methods to obtain molecular information are briefly summarized, and actual examples to demonstrate the importance of this type of investigations are selected from both natural minerals (diamond, quartz, hematite, corundum, beryl, phlogopite) and synthetic crystals (SiC, diamond, corundum, beryl).

  2. Separation of enantiomers by continuous preferential crystallization: Experimental realization using a coupled crystallizer configuration

    DEFF Research Database (Denmark)

    Chaaban, Joussef Hussein; Dam-Johansen, Kim; Kiil, Søren

    2013-01-01

    The experimental realization of a continuous preferential crystallization process, consisting of two mixed-flow crystallizers coupled via crystal-free liquid exchange streams and with only the liquid phases operating continuously, is addressed. Experiments in triplicate, using the conglomerate....... Successful enantioseparation by crystal growth, with the repeatability being within ±10% deviation, was obtained. However, slow crystal growth, due to a low surface integration rate, led to a negligible consumption of the desired enantiomer added in the feed solution, resulting in low productivities....... Productivities, yields, and purities of solid products were influenced by the morphological differences in the seed crystals. Due to irregularly shaped seed crystals, increase in the productivities and yields were achieved in the L-Tank. Lower purities of solid products from the L-Tank compared to purities...

  3. Nonlinear and quantum optics with liquid crystals

    International Nuclear Information System (INIS)

    Lukishova, Svetlana G

    2014-01-01

    Thermotropic liquid crystals' usual application is display technology. This paper describes experiments on light interaction with pure and doped liquid crystals under for these materials unconventional incident light powers: (1) under high-power laser irradiation, and (2) at the single-photon level. In (1), I will outline several nonlinear optical effects under high-power, nanosecond laser irradiation which should be taken into account in the design of lasers with liquid crystal components and in fabrication of optical power limiters based on liquid crystals: (1.1) athermal helical pitch dilation and unwinding of cholesteric mirrors (both in free space and inside laser resonators); (1.2) some pitfalls in measurements of refractive nonlinearity using z-scan technique under two-photon or linear absorption of liquids; (1.3) the first observation of thermal lens effects in liquid crystals under several-nanosecond, low-pulse-repetition rate (2-10 Hz) laser irradiation in the presence of two-photon absorption; (1.4) feedback-free kaleidoscope of patterns (hexagons, stripes, etc.) in dye-doped liquid crystals. In (2), at the single-photon level, it will be shown that with a proper selection of liquid crystals and a single-emitter dopant spectral range, liquid crystal structures can be used to control emitted single photons (both polarization and count rate). The application of the latter research is absolutely secure quantum communication with polarization coding of information. In particular, in (2.1), definite handedness, circular polarized cholesteric microcavity resonance in quantum dot fluorescence is reported. In (2.2), definite linear polarization of single (antibunched) photons from single-dye-molecules in planar-aligned nematic host is discussed. In (2.3), some results on photon antibunching from NV-color center in nanodiamond in liquid crystal host and circularly polarized fluorescence of definite handedness from nanocrystals doped with trivalent ions of

  4. Porphyroblast crystallization kinetics: the role of the nutrient production rate

    DEFF Research Database (Denmark)

    Schwarz, Jens-Oliver; Engi, Martin; Berger, Alfons

    2011-01-01

    The mechanisms that govern porphyroblast crystallization are investigated by comparing quantitative textural data with predictions from different crystallization models. Such numerical models use kinetic formulations of the main crystallization mechanism to predict textural characteristics, such ...

  5. Characterization of lime mortar additivated with crystallization modifiers

    NARCIS (Netherlands)

    Granneman, S.J.C.; Lubelli, B.; van Hees, R.P.J.

    2018-01-01

    Additivating mortars with crystallization modifiers is a novel approach to mitigate salt crystallization damage in historic masonry. Once verified the effectiveness of crystallization modifiers in bulk solution, the next step consists in verifying whether: (i) modifiers are still effective when

  6. Biosynthesis of Silver and Gold Crystals Using Grapefruit Extract

    Directory of Open Access Journals (Sweden)

    Chen Long

    2016-01-01

    crystals is discussed, indicating that the soluble biomolecules such as protein(s and vitamin C in grapefruit extract may play a crucial role in defining the morphology and/or crystal phase of silver and gold crystals.

  7. Synthesis and characterization of gel-grown cobalt tartrate crystals

    Indian Academy of Sciences (India)

    ... in electronics, optics and industries. A series of pure and mixed crystals ... bility method. A few researchers reported the growth of crystals of strontium tartrate ... grow it by chemical reaction method using the gel technique. The crystallization ...

  8. Induction of labor with titrated oral misoprostol solution versus oxytocin in term pregnancy: randomized controlled trial Indução do trabalho de parto por meio de solução oral titulada de misoprostol versus oxitocina em gestação a termo: estudo controlado randomizado

    Directory of Open Access Journals (Sweden)

    Rezvan Aalami-Harandi

    2013-02-01

    Full Text Available PURPOSE: To evaluate the effectiveness and the safety of orally administered misoprostol in comparison to intravenously infused oxytocin for labor induction in term pregnant women. METHODS: Between 2008 and 2010, a total of 285 term pregnant women whom were candidate for vaginal delivery were assessed for eligibility to enter the study. Twenty five patients were excluded for different reasons; and 260 included women were randomly assigned to one of the two groups according to the method of treatment, misoprostol or oxytocin. The misoprostol group received 25 µg every 2 hours for up to 24 hours for induction. The oxytocin group received an infusion of 10 IU which was gradually increased. The time from induction to delivery and induction to the beginning of the active phase and successful inductions within 12, 18, and 24 hours were recorded. The trial is registered at irct.ir, number IRCT2012061910068N1. RESULTS: Failure of induction, leading to caesarean section was around 38.3% in the oxytocin group and significantly higher than that of the misoprostol group (20.3% (pOBJETIVO: Avaliar a eficácia e segurança do misoprostol administrado por via oral em comparação à infusão de oxitocina para a indução do trabalho de parto em gestantes a termo. MÉTODOS: Entre 2008 e 2010, um total de 285 gestantes a termo candidatas para parto vaginal foram avaliadas quanto à eligibilidade para inclusão no estudo. Vinte e cinco pacientes foram excluídas por várias razões, e as 260 mulheres incluídas foram divididas aleatoriamente em dois grupos de acordo com o método de tratamento, misoprostol ou oxitocina. O grupo tratado com o misoprostol recebeu 25 µg cada 2 horas durante um máximo de 24 horas para indução. O grupo tratado com oxitocina recebeu infusão de 10 UI, que foi aumentada gradativamente. O tempo a partir da indução até o início da fase ativa e as induções bem-sucedidas dentro de 12, 18 e 24 horas foram registrados. O ensaio foi

  9. Small-angle neutron scattering technique in liquid crystal studies

    International Nuclear Information System (INIS)

    Shahidan Radiman

    2005-01-01

    The following topics discussed: general principles of SAS (Small-angle Neutron Scattering), liquid crystals, nanoparticle templating on liquid crystals, examples of SAS results, prospects of this studies

  10. Shape Evolution of Detached Bridgman Crystals Grown in Microgravity

    Science.gov (United States)

    Volz, M. P.; Mazuruk, K.

    2015-01-01

    A theory describing the shape evolution of detached Bridgman crystals in microgravity has been developed. A starting crystal of initial radius r0 will evolve to one of the following states: Stable detached gap; Attachment to the crucible wall; Meniscus collapse. Only crystals where alpha plus omega is great than 180 degrees will achieve stable detached growth in microgravity. Results of the crystal shape evolution theory are consistent with predictions of the dynamic stability of crystallization (Tatarchenko, Shaped Crystal Growth, Kluwer, 1993). Tests of transient crystal evolution are planned for ICESAGE, a series of Ge and GeSi crystal growth experiments planned to be conducted on the International Space Station (ISS).

  11. Fatores perinatais associados a recém-nascidos de termo com pH<7,1 na artéria umbilical e índice de Apgar <7,0 no 5º minuto Perinatal factors associated with pH<7.1 in umbilical artery and Apgar 5 min <7.0 in term newborn

    Directory of Open Access Journals (Sweden)

    Patrícia de Moraes De Zorzi

    2012-08-01

    Full Text Available OBJETIVO: Avaliar os fatores perinatais associados a recém-nascidos de termo com pHPURPOSE: To assess perinatal factors associated with term newborns with pH<7.1 in the umbilical artery and 5th min Apgar score<7,0. METHODS: Retrospective case-control study carried out after reviewing the medical records of all births from September/1998 to March/2008, that occurred at the General Hospital of Caxias do Sul. The inclusion criterion was term newborns who presented a 5th min Apgar score <7.0 and umbilical artery pH<7.10. In the univariate analysis, we used the Student's t-test and the Mann-Whitney test for continuous variables, the c² test for dichotomous variables and risk estimation by the odds ratio (OR. The level of significance was set at p<0.05. RESULTS: Of a total of 15,495 consecutive births, 25 term neonates (0.16% had pH<7.1 in the umbilical artery and a 5th min Apgar score <7.0. Breech presentation (OR=12.9, p<0.005, cesarean section (OR=3.5, p<0.01 and modified intrapartum cardiotocography (OR=7.8, p<0.02 presented a significant association with the acidosis event. Among the fetal characteristics, need for hospitalization in the neonatal intensive care unit (OR=79.7, p <0.0001, need for resuscitation (OR=12.2, p <0.0001 and base deficit were associated with the event (15.0 versus -4.5, p<0.0001. CONCLUSION: Low Apgar score at the 5th min of life associated with pH<7.1 in the umbilical artery can predict adverse neonatal outcomes.

  12. Macromolecular Crystal Growth by Means of Microfluidics

    Science.gov (United States)

    vanderWoerd, Mark; Ferree, Darren; Spearing, Scott; Monaco, Lisa; Molho, Josh; Spaid, Michael; Brasseur, Mike; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    We have performed a feasibility study in which we show that chip-based, microfluidic (LabChip(TM)) technology is suitable for protein crystal growth. This technology allows for accurate and reliable dispensing and mixing of very small volumes while minimizing bubble formation in the crystallization mixture. The amount of (protein) solution remaining after completion of an experiment is minimal, which makes this technique efficient and attractive for use with proteins, which are difficult or expensive to obtain. The nature of LabChip(TM) technology renders it highly amenable to automation. Protein crystals obtained in our initial feasibility studies were of excellent quality as determined by X-ray diffraction. Subsequent to the feasibility study, we designed and produced the first LabChip(TM) device specifically for protein crystallization in batch mode. It can reliably dispense and mix from a range of solution constituents into two independent growth wells. We are currently testing this design to prove its efficacy for protein crystallization optimization experiments. In the near future we will expand our design to incorporate up to 10 growth wells per LabChip(TM) device. Upon completion, additional crystallization techniques such as vapor diffusion and liquid-liquid diffusion will be accommodated. Macromolecular crystallization using microfluidic technology is envisioned as a fully automated system, which will use the 'tele-science' concept of remote operation and will be developed into a research facility for the International Space Station as well as on the ground.

  13. Discovery Mondays: crystals and particles for medicine

    CERN Multimedia

    2003-01-01

    Question: what are as heavy as lead, as clear as glass, and appear as tiny specks in a doctor's scanner but large as life in a physicist's detector? Answer: the crystals you will be able to observe in all their facets on 1 September at the start of a new season of Discovery Mondays at Microcosm. Come along and meet the CERN physicists who use crystals not only in their detectors but also in the latest generation of scanners. Four workshops will be organised, each devoted to a different medical imaging technique. The first workshop will be run by a physicist from the Crystal Clear collaboration, who will present her collaboration's special breed of crystals, which emit light when they are traversed by high-energy particles, and explain to you these crystals' role in Positron Emission Tomographs. The second workshop will focus on an imaging technique known as the Compton Camera, also based on scintillating crystals. Crystals worth looking at and admiring. Come to the next Discovery Monday to find out how they ...

  14. Growth and Characterization of Tetraphenylphosphonium Bromide Crystal

    Directory of Open Access Journals (Sweden)

    Guangqiang Wang

    2017-05-01

    Full Text Available Multiple-phenyl phosphorous compounds are a group of chemical materials that have been used as reactants, pharmaceutical intermediates, extractants, and catalysts in organic synthetic reactions. However, the crystal growth of bulk crystals of multiple-phenyl phosphorous compounds, which may expand their applications in photonics technology, have been largely overlooked. In this article, the crystal growth of tetraphenylphosphonium bromide (TPPB has been studied in organic solvents and water. The crystal structures and crystallization features are analyzed by X-ray diffraction data. By a slow temperature-lowering method, a single-crystal of TPPB (2H2O with the size of 27 × 20 × 20 mm3 has been obtained in water. The basic thermal and optical properties were characterized. We find that the TPPB (2H2O crystal shows excellent transparent property in the near-IR region. Large Raman shifts and strong Raman scattering intensity indicate that TPPB is a potential candidate in Raman-scattering-based nonlinearity applications.

  15. Kinetics of Crystallization in Polydisperse Emulsions.

    Science.gov (United States)

    Kashchiev; Kaneko; Sato

    1998-12-01

    The kinetics of isothermal crystallization of the droplets in polydisperse emulsions are analyzed under the condition that each emulsion droplet gives birth to one nucleus only. Expressions are derived for the time dependences of the number of crystallized droplets and the fraction of crystallized droplet volume in the cases of either volume or surface nucleation of the crystals in the droplets. The time for half-crystallization is determined as a function of the emulsion polydispersity, and it is found that the more polydisperse the emulsion, the shorter this time in comparison with that for the corresponding monodisperse emulsion. Formulae are also obtained for the change of the velocity Kv of propagation of ultrasound through polydisperse emulsions during the time t of isothermal crystallization of the droplets in them. Good agreement is found between theory and experiment in an analysis of available Kv(t) data for crystallization in polydisperse palm oil-in-water and n-hexadecane-in-water emulsions. The results obtained are directly applicable to devitrification and polymorphic transformation of disperse solid phases. Copyright 1998 Academic Press.

  16. Design of Double PG Crystal Neutron Diffractometer

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; El-Mesiry, M.S.; Fathallah, M.

    2011-01-01

    The design of a diffractometer containing two pyrolytic graphite (PG) crystals to select monochromatic neutrons in the range of wavelengths longer than 0.26 nm is given. The first crystal is high oriented pyrolytic graphite (HOPG) set at glancing angle to reflect monochromatic neutrons with a selected wavelength. The second is a low quality PG crystal filter, set at take-off-angle such that, it transmits the selected monochromatic neutrons and rejects the higher order contaminations accompanying the first order reflection. It was shown that, 2 mm thick of PG crystal having 0.30 FWHM on mosaic spread are the optimum parameters of monochromator PG crystal. While the optimum thickness and mosaic spread of the PG crystal filter were selected to have low contamination factor of higher order reflections. The optimum parameters of the PG filter crystal were calculated using the computer package Graphite recently developed in our laboratory. Calculation shows that, 3 cm thick PG filter (20 on mosaic spread) is sufficient to almost eliminate the higher order contaminations accompanying the main monochromatic neutrons with

  17. Surface deterioration of ammonium acid phthalate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Barrus, D.M.; Blake, R.L.; Burek, A.J.

    1976-01-01

    In working with various acid phthalate crystals for low energy X-ray spectroscopy, we have observed a relatively rapid surface degradation of ammonium acid phthalate in comparison with similar crystals was observed. It was found that two different samples degraded in a few days upon exposure to high vacuum (10/sup -6/ - 10/sup -7/ torr). The same crystals showed similar effects when exposed to room atmosphere for two to three weeks. One of these crystals deteriorated while kept constantly in a desiccator jar for about two years. The desiccator environment seems to be the most favorable. The observed difference in the surface of these crystals might be described as a change from a transparent, glasslike condition to a white, powderlike haze somewhat akin to frosted glass. A two week exposure to vacuum for a freshly cleaved crystal caused the integrated coefficient of reflection at 23.6 A to decrease by a factor of 2.5. The degraded surface areas tend to form definite rhombohedral patterns. Since the external symmetry of ammonium acid phthalate crystals is rhombohedral, this suggests that the degradation we observe takes place in the form of large etched figures. A possible mechanism may be sublimation, which would proceed more rapidly in vacuum than in air. It is concluded that ammonium acid phthalate should be kept in a desiccator environment as much as possible. Exposures to vacuum should be brief and critical diffraction measurements should be done using a freshly cleaved surface.

  18. Neutrons and the crystal ball experiments

    International Nuclear Information System (INIS)

    Alyea, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H.; Stanislaus, S.

    1997-01-01

    The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4π st (20 degree le θ le 160degree and 0degree le φ le 360degree) from the center. The Crystal Ball detector was used for two long series of experiments at the e + e - colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include π - pr a rrow neutrals with pion beam momenta approximately400-750 MeV/c and K - pr a rrow neutrals with kaon beam momenta approximately600-750 MeV/c. Each of these reactions will include a neutron in the final state. whereas the fraction of e + e - interactions with neutrons at SLAC or DESY was quite small. Consequently, there is relatively little experience understanding the behavior of neutrons in the Crystal Ball

  19. Crystal growth and characterization of new semiorganic nonlinear optical single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kulshrestha, Shobha, E-mail: shobha011986@gmail.com; Shrivastava, A. K., E-mail: ashwaniaks@rediffmail.com [School of Studies in Physics, Jiwaji University Gwalior (M.P.) – 474 011 (India)

    2016-05-06

    An organic material of a L-histidine monohydrochloride single crystal was grown in a distilled water solution using the slow evaporation method at 40–45°C. The grown crystal was transparent and colourless, with a size of about 20 × 9 × 5 mm{sup 3}, obtained within a period of 21 days. The solubility of grown crystals have found out at various temperatures. The UV-visible transmittance studies show that the grown crystals have wide optical transparency in the entire visible region It is observed that the crystal has transparency window from 255nm to 700nm and its energy gap (Eg) found to be is 3.1eV. The grown crystal was subjected to powder X-ray diffraction analysis, confirming that the orthorhombic crystalline nature of the crystal. To identify the surface morphology, the as grown crystal was subjected to FE-SEM technique. The chemical composition of the grown crystal was estimated by Energy dispersive X-ray analysis. The optical behaviour of the grown crystal was analyzed by PL study.

  20. On-line monitoring of the crystallization process: relationship between crystal size and electrical impedance spectra

    International Nuclear Information System (INIS)

    Zhao, Yanlin; Yao, Jun; Wang, Mi

    2016-01-01

    On-line monitoring of crystal size in the crystallization process is crucial to many pharmaceutical and fine-chemical industrial applications. In this paper, a novel method is proposed for the on-line monitoring of the cooling crystallization process of L-glutamic acid (LGA) using electrical impedance spectroscopy (EIS). The EIS method can be used to monitor the growth of crystal particles relying on the presence of an electrical double layer on the charged particle surface and the polarization of double layer under the excitation of alternating electrical field. The electrical impedance spectra and crystal size were measured on-line simultaneously by an impedance analyzer and focused beam reflectance measurement (FBRM), respectively. The impedance spectra were analyzed using the equivalent circuit model and the equivalent circuit elements in the model can be obtained by fitting the experimental data. Two equivalent circuit elements, including capacitance ( C 2 ) and resistance ( R 2 ) from the dielectric polarization of the LGA solution and crystal particle/solution interface, are in relation with the crystal size. The mathematical relationship between the crystal size and the equivalent circuit elements can be obtained by a non-linear fitting method. The function can be used to predict the change of crystal size during the crystallization process. (paper)