• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 97
  • 59
  • 15
  • 14
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 221
  • 55
  • 39
  • 37
  • 34
  • 32
  • 25
  • 24
  • 22
  • 21
  • 19
  • 18
  • 18
  • 17
  • 15
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Ligas à base de cobalto depositadas quimicamente: propriedades magnéticas e catalíticas / Electroless cobalt alloys: magnetic and catalytic properties

Mauro Celso Ribeiro 23 March 2009 (has links)
A influência de variáveis do banho na composição, microestrutura e nas propriedades magnéticas de filmes de CoB preparados por deposição química foi estudada. Dois diferentes tipos de agentes complexantes foram utilizados: citrato de sódio e Glicina. Filmes com menor teor de boro foram obtidos com o uso de Glicina como complexante. A deposição de Co é acelerada em presença de Glicina ou de amônia no banho, porque ambos evitam a diminuição do pH na interface solução/filme de CoB em crescimento. A coercividade dos filmes variou em função do teor de boro, sendo que filmes com maior teor de boro apresentaram mais baixa coercividade. Catalisadores de Co/Al2O3 são utilizados na síntese de combustíveis à partir de derivados do Gás Natural (Síntese de Fischer-Tropsch - SFT). O processo usual de preparação destes catalisadores, denominado impregnação úmida, consiste na impregnação do substrato em solução de sal de Co(II), secagem/calcinação e redução com H2 a 300/350 °C. Uma fração considerável do Co não é reduzida à fase metálica na etapa de redução, o que resulta em perdas de área ativa para a catálise da SFT. Normalmente pequenas quantidades de metais preciosos tais como Pt, Ru ou Pd são adicionadas para catalisar a redução dos óxidos de cobalto e aumentar a área superficial ativa do catalisador, o que representa um grande incremento no custo destes catalisadores. Nesta tese, foram investigadas duas propostas alternativas de solução para este problema: a preparação de catalisadores de Co por deposição química sobre Al2O3 e a preparação pelo método usual, mas com adição de pequenas quantidades de Cu,Ag e Au, dos quais Cu e Ag têm custo mais baixo do que os metais preciosos normalmente utilizados. Co foi depositado quimicamente sobre γ-Al2O3, previamente ativada com pequenas quantidades de Pd, utilizando NaBH4 como redutor. Uma amostra de catalisador de CoB/PdAl2O3 (contendo 13,4 % em massa de Co e c.a. 25% at. de boro) foi obtida e caracterizada por RTP, Quimissorção de H2 e XRD, assim como foram efetuados testes de SFT sob diferentes temperaturas de ativação. Para efeito de comparação, foi preparado por impregnação úmida uma amostra de Co/PdAl2O3 contendo 11% em massa de Co, sobre a mesma alumina ativada com Pd utilizada na preparação dos catalisadores de CoB/PdAl2O3. Embora a amostra de catalisador de CoB/PdAl2O3 tenha tido menor área superficial ativa do que a amostra de catalisador de Co/PdAl2O3, sua atividade catalítica foi sensivelmente maior. Essa diferença pode ser explicada supondo-se que o boro é solubilizado durante a reação, deixando uma fase de Co metálico altamente dispersa. Catalisadores de Co/Al2O3 promovidos por metais do grupo 11 foram preparados por impregnação úmida. Além da caracterização por RTP, Quimissorção de H2/titulação de O2 e XRD, a estrutura das amostras de catalisador foi estudada por XANES/EXAFS. Dos resultados de EXAFS e do fato de que altos teores de Cu e Au levaram à desativação do catalisador, é sugerido que durante a redução, o promotor é segregado para a superfície das partículas de Co. Dos três metais testados, Ag e Au apresentaram maior efeito promotor da atividade catalítica, proporcionando maior área superficial ativa para catálise da SFT. Não houve modificações importantes na seletividade dos catalisadores por conta da presença destes metais. / The influence of bath composition on the boron content, microstructure and magnetic properties CoB films deposited by chemical deposition was studied. Two different complexing agents were used in this study: sodium citrate and Glycine. CoB films with lower boron content were obtained with the use of a Glycine containing bath. The Co deposition is accelerated when either Glycine or ammonia is present in the solution because both substances prevent the decrease of the pH in the region near the CoB film/solution interface. The coercivity of the films varied in function of the boron content, as films with larger boron contents showed lower coercivities. Co/Al2O3 is used as a catalyst for the synthesis of liquid fuels from either coal or natural gas derivatives (Fischer Tropsch Synthesis FTS). The usual preparation procedure of such catalysts, known as wet impregnation, consists in the Al2O3 impregnation with a Co(II) aqueous solution, water evaporation/calcination and reduction with H2 at 300/350 °C. A considerable fraction of the cobalt oxides formed during calcination is not reduced to Co0 during reduction and this leads to active area loss. Normally, small quantities of precious metals like Pt, Ru or Pd are added to promote the reduction of cobalt oxides and therefore increase the active area of the Co/Al2O33 catalyst, yet these metals are extremely expansive. In this thesis, two different approaches to solve this problem are presented: the preparation of Co/Al2O3 by chemical deposition of the metallic phase and the use of Cu, Ag or Au (from which, Cu and Ag are cheaper metals) as promoters on wet impregnation prepared Co/Al2O3 catalysts. Cobalt was chemically deposited on γ-Al2O3, activated with a small quantity of Pd, with NaBH4 as a reducing agent. The resulting CoB/PdAl2O3 sample (with 13,4 % wt. Co and approximately 25 % at. of boron) was characterized by TPR, H2 Chemisorption and XRD, as well as SFT tests were made with the catalyst at different pre-reduction temperatures. For the sake of comparison a Co/PdAl2O3 catalyst sample with almost the same Co loading (11 % wt.) was prepared by wet impregnation on the same Pd-activated Al2O3 used to prepare the CoB/PdAl2O3 sample. Although the CoB/PdAl2O3 has a smaller active surface area (measured by H2 Chemisorption) than that of the Co/PdAl2O3 sample, it presented a much higher catalytic activity for the SFT. This difference may be explained assuming that boron impurities (present in the catalyst as boron oxides) is solubilized during the reaction leaving a highly dispersed Co phase. Group 11 promoted Co/Al2O3 catalysts were prepared by wet impregnation and characterized by TPR, H2 Chemisorption/O2 pulse oxidation, XRD and XANES/EXAFS. From the EXAFS results and from the fact that higher loadings of Cu and Au lead to catalyst deactivation, it is proposed that in the reduced catalyst the SFT inactive promoter is segregated to the surface. Silver and Gold were the most active in promoting Co reduction and therefore increasing catalytic activity for the SFT. No important modification in the selectivity of the reaction was observed.
182

Promotoras Legais Populares: avançando na luta pela igualdade de gênero e na compreensão da Educação de Jovens e Adultos

Santos, Raquel Auxiliadora dos 24 February 2014 (has links)
Made available in DSpace on 2016-06-02T19:39:51Z (GMT). No. of bitstreams: 1 6475.pdf: 1412640 bytes, checksum: 1124fb478e71b1f826bf924b9193c8d4 (MD5) Previous issue date: 2014-02-24 / The Education of Youth and Adults (EJA) undergoes a process of paradigm change from a compensatory conception of basic education to lifelong learning. As a teaching modality, EJA needs to be understood in the broadest sense, connecting school experience with people s life and work expectations by seeking to contemplate their needs. The objective of this work is to describe and analyze one experience of EJA understood in the context of Lifelong Education: the Popular Legal Promoters Course (PLPs), which aims to train adult women to be multipliers of rights, laws and legal mechanisms in their communities. Women are still subordinate to hierarchies in different social contexts and struggle daily to uphold their rights. This research was carried out by conducting in-depth interviews with four PLPs graduated in the third group of the course in the city of Sao Carlos. Through content analysis and the Critical Communicative Methodology themes and categories were prepared highlighted in their transforming and exclusionary elements. Among the main elements of the PLPs course that contribute to EJA we have: practical utility of the content; the form of openly relation with knowledge; dialogical education; the importance of women's themes and feminism as well as multidisciplinary content. In this sense, the present dissertation focuses on the Popular Legal Promoters education as a Lifelong Education experience, which brings elements to the reformulation in the organization of EJA as a formative space that better suits women. / A Educação de Jovens e Adultos (EJA) passa por um processo de mudança de paradigma entre uma concepção compensatória da formação básica e uma aprendizagem ao longo da vida. Enquanto modalidade de ensino, a EJA necessita ser compreendida no sentido mais amplo, conectando a experiência escolar, com as expectativas de vida e de trabalho das pessoas, buscando contemplar as suas necessidades. Busca-se neste trabalho descrever e analisar uma experiência de EJA, compreendida na perspectiva da Educação ao Longo da Vida: o Curso Promotoras Legais Populares (PLPs), que tem como objetivo formar mulheres adultas, para que sejam multiplicadoras dos direitos, leis e mecanismos jurídicos em suas comunidades. As mulheres ainda encontram-se subordinadas à hierarquias em diversos âmbitos sociais, e lutando cotidianamente para que seus direitos sejam assegurados. Essa pesquisa se desenvolveu por meio da realização de entrevistas em profundidade, com quatro PLPs, formadas na terceira turma do curso da cidade de São Carlos. Por meio da análise de conteúdo e da Metodologia Comunicativa Crítica, foram elaboradas temáticas e categorias, destacadas em seus elementos transformadores e excludentes. Dentre os principais elementos do curso de PLPs que contribuem para a EJA, temos: utilidade prática do conteúdo; a forma de relação com o conhecimento, de maneira aberta; a formação dialógica; a importância dos temas das mulheres e do feminismo e conteúdo multidisciplinar. Desta forma, a presente dissertação trata a formação das Promotoras Legais Populares, como uma experiência de Educação ao Longo da Vida, que traz elementos para a reformulação na organização da EJA, como espaço formativo que melhor atenda as mulheres.
183

Extratos vegetais como alternativas aos antimicrobianos promotores do crescimento de leitões recém-desmamados / Herbal extracts as alternatives to antimicrobial growth promoters of weanling pigs

Leandro Batista Costa 03 February 2006 (has links)
O uso de antimicrobianos como promotores do crescimento na alimentação animal tem proporcionado uma melhora considerável no desempenho animal. Porém, seu uso vem sendo proibido em diversos países e, face a esta restrição, tem-se buscado alternativas aos antimicrobianos promotores do crescimento. Assim, o objetivo do trabalho foi avaliar extratos vegetais como alternativas aos antimicrobianos promotores do crescimento de leitões recémdesmamados, por meio do desempenho e da morfometria de órgãos dos animais. Um experimento em blocos casualizados, com 35 dias de duração, foi realizado para testar cinco tratamentos: controle - ração basal; antimicrobiano - basal com colistina + tiamutin (75 ppm de cada); extrato de cravo (Ec) – basal com 420 ppm de extrato vegetal (210 ppm de óleo essencial de cravo + 210 ppm do princípio ativo eugenol); extrato de orégano (Eo) – basal com 420 ppm de extrato vegetal (210 ppm de óleo essencial de orégano + 210 ppm do princípio ativo carvacrol) e extrato de cravo + orégano (E c+ Eo) – basal com 420 ppm de extrato vegetal (105 ppm de óleo essencial de cravo + 105 ppm de eugenol e 105 ppm de óleo essencial de orégano + 105 ppm de carvacrol), sendo todos os extratos vegetais encapsulados. Para o desempenho, foram utilizados 80 leitões, com idade média em torno de 24 dias e peso inicial de 7,19 ± 1,55, oito repetições por tratamento e dois animais por unidade experimental. Ao final do período experimental, um animal de cada baia, dos quatro primeiros blocos, foi abatido para morfometria de órgãos. Foram testados contrastes específicos de importância prática. No período de 1 a 14 dias, animais do tratamento antimicrobiano apresentaram melhor conversão alimentar (CA) que a média dos animais dos tratamentos com extratos (P=0,02), enquanto que animais do tratamento Ec apresentaram melhor CA que os do tratamento Eo (P=0,03). No período total, os animais do tratamento antimicrobiano apresentaram maior peso aos 35 dias (P35) (P=0,05) e ganho diário de peso (GDP) (P=0,06) que a média dos animais dos tratamentos com extratos. Os animais do tratamento Ec + Eo apresentaram maior P35 (P=0,02) e GDP (P=0,02) em relação à média dos animais dos outros tratamentos com extratos. Para a morfometria de órgãos os antimicrobianos proporcionaram maior peso relativo dos rins (P=0,01) em relação aos outros tratamentos de extratos. De modo geral, os antimicrobianos proporcionaram os melhores desempenhos de leitões em fase de creche. Quanto aos extratos vegetais, a combinação de Ec + Eo acarretou um desempenho muito próximo àquele obtido com os antimicrobianos, demonstrando ser uma alternativa promissora como promotor do crescimento de leitões recém-desmamados. / The use of antimicrobial as growth promoters in the animal feed has been related to an increase on animal performance. However, due to the restriction of many countries to the use of antimicrobial as growth promoters, alternatives are being studied. So, the purpose of this work was to evaluate herbal extracts as alternatives to antimicrobial growth promoters of weanling pigs based on performance and organ weights. A 35-d randomized complete block design experiment was carried out to compare five treatments: control - basal diet; antimicrobial - basal diet with colistin + tiamutin (75 ppm of each); herbal extract of clove (Ec) – basal diet with 420 ppm of herbal extract (210 ppm of essential oil of clove + 210 ppm of active compound eugenol); herbal extract of oregano (Eo) – basal diet with 420 ppm of herbal extract (210 ppm of essential oil of oregano + 210 ppm of active compound carvacrol); and herbal extract of clove + oregano (Ec + Eo) – basal diet with 420 ppm of herbal extract (105 ppm of essential oil of clove + 105 ppm of eugenol and 105 ppm of essential oil of oregano + 105 ppm of carvacrol ), being all the herbal extracts encapsulated. Eighty pigs (average age around 24 d and initial live weight of 7.19 ± 1.55 kg), eight replications per treatment, and two animals per experimental unit were used for performance data. At the end of experimental period, an animal per pen of first four blocks was slaughtered for organ morphometry data. Specific contrasts of practical importance were tested. For 1-14 d period, pigs fed antimicrobial showed better fed conversion (CA) than the mean of those fed herbal extract treatments (P=.02), while pigs fed Ec gave better CA than those fed Eo (P=.03). For the total period, pigs fed antimicrobial showed higher body weight at 35 days (P35) (P=.05) and average daily gain (GDP) (P=.06) than the mean of those fed herbal extracts. Pigs fed Ec + Eo gave higher P35 (P=.02) and GDP (P=.02) than the mean of those fed other herbal extract treatments. For the organ morphometry data, the antimicrobials provided a higher relative weight of kidneys (P=.01) than the mean of the other treatments with herbal extracts. Overall, antimicrobial agents provided the best performance of weanling pigs. Concerning to herbal extracts, the combination of clove and oregano provided performance close to that of pigs fed antimicrobials, showing that this combination can be a potential alternative as growth promoter of weanling pigs.
184

Efeito da VariaÃÃo de LÃtio em Catalisadores de Ferro tendo PotÃssio e Cobre como Promotores para a SÃntese Fischer-Tropsch / EFFECT OF LITHIUM IN IRON BASED CATALYST FOR FISCHER-TROPSCH SYNTHESIS CONTAINING POTASSIUM AND COPPER AS PROMOTERS

Enio Costa 24 February 2010 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Diante das atuais exigÃncias ambientais e uma possÃvel instabilidade no mercado internacional de petrÃleo, o processo de SÃntese de Fischer-Tropsch (SFT) representa uma nova trajetÃria tecnolÃgica na busca de combustÃveis alternativos limpos. A SFT Ã uma reaÃÃo de polimerizaÃÃo, na qual o gÃs de sÃntese (H2 + CO) reage na presenÃa de um catalisador produzindo uma mistura de hidrocarbonetos. A fim de se estudar o efeito das condiÃÃes operacionais (temperatura e pressÃo) e do teor de lÃtio como promotor em catalisadores de ferro para a (SFT) foram sintetizados trÃs catalisadores suportados em sÃlica. A composiÃÃo desses catalisadores em base molar seguiu o padrÃo: 100Fe/5Cu/24K/240SiO2, variando apenas a concentraÃÃo de lÃtio, em 06Li, 12Li e 24Li. Os catalisadores foram caracterizados atravÃs das tÃcnicas de fluorescÃncia de raios-X, difraÃÃo de raios-X, anÃlise termogravimÃtrica, anÃlise textural e reduÃÃo a temperatura programada. Foi realizado um planejamento experimental fatorial para cada catalisador e as variÃveis respostas selecionadas foram o nÃmero mÃdio de carbono (Nm), a dispersÃo e a curtose da distribuiÃÃo dos produtos. A pressÃo variou de 240 a 270ÂC e a pressÃo de 20 a 30 atm. As reaÃÃes foram conduzidas em um reator de leito de lama de alta pressÃo e os produtos gerados foram analisados por cromatografia gasosa e identificados atravÃs de padrÃes internos e quantificados a partir de balanÃos molares e programa computacional de estimativa de Ãrea dos picos. A distribuiÃÃo de hidrocarbonetos resultantes da reaÃÃo da SÃntese de Fischer-Tropsch apresentou comportamento de uma distribuiÃÃo normal para fraÃÃo diesel e graxa, semelhante ao comportamento de uma Gaussiana para todos os catalisadores nas condiÃÃes estudadas. Os produtos lÃquidos obtidos nas corridas experimentais da SFT sÃo constituÃdos principalmente de n-parafinas. Os resultados de todos os experimentos para os trÃs tipos de catalisador apresentaram quantidades significativas de n-parafinas na faixa de 20 a 36 Ãtomos de carbono. A anÃlise estatÃstica da perturbaÃÃo das variÃveis independentes do processo (temperatura, pressÃo e concentraÃÃo de lÃtio no catalisador) sobre o nÃmero mÃdio de carbonos mostra que apenas a concentraÃÃo de lÃtio no catalisador tem um efeito significativo para um intervalo de confianÃa de 90%. A concentraÃÃo de lÃtio apresenta influÃncia negativa, indicando que sua utilizaÃÃo desfavorece a produÃÃo de hidrocarbonetos de maior peso molecular. / New environmental regulations and a possible instability in the international oil market have led to a renewal interest in the Fischer-Tropsch Synthesis (FTS), which is an alternative to produce more environmental friendly fuels. The FTS is a polymerization reaction, in which syngas (H2 + CO) reacts in the presence of catalyst to produce hydrocarbons. Three iron-based catalysts supported in silica and promoted with lithium were synthesized and the effects of lithium content and operating conditions (temperature and pressure) were studied. The composition of the catalysts was based on 100Fe/5Cu/24K/240SiO2 (molar basis) with varying lithium concentration 06Li, 12Li e 24Li. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, textural analysis and temperature programming reduction. An experimental planning was carried out for each catalyst, varying the temperature from 240 to 270 ÂC and the pressure from 20 to 30 atm. The answer variables were the average carbon number (Nm), dispersion and curtosis of the product distribution. The reactions were carried out in a slurry bed reactor and the products were analyzed by gas chromatography. The products were identified by means of internal standards and quantified by mass balance. The product distribution of the FTS presented a normal distribution in the diesel and wax region. The distribution was similar to a Gaussian curve for all catalysts. The liquid products consisted mainly of n-parafins. The results for all catalysts presented significant quantities of n-parafins in the range of 20 to 36 carbons. The perturbation analysis of the independent variables (temperature, pressure and lithium content) showed that only the lithium content has a significant effect over the average carbon number, at a 90% confidence level. The lithium content presented a negative effect over the average carbon number.
185

Expressão do gene uidA dirigido por promotores preferencialmente ativados no floema de plantas transgênicas de laranja doce inoculadas com Candidatus Liberibacter asiaticus / Expression of the uidA gene driven by promoters preferentially activated in the phloem of transgenic sweet orange inoculated with Candidatus Liberibacter asiaticus

Luzia Yuriko Miyata 15 May 2014 (has links)
O Brasil é o maior produtor de laranja doce do mundo, mas a história da citricultura brasileira é marcada por sucessivas perdas devido a pragas e doenças que atacam os pomares. Entre as doenças que afetam os pomares de citros, o huanglongbing (HLB) tem merecido destaque nos últimos anos. O HLB já é conhecido desde 1900 na China, mas no Brasil essa doença está presente desde 2004 e tem causado perdas significativas a citricultura. Essa doença é associada a três espécies de \"Candidatus Liberibacter\", mas no Brasil a espécie Candidatus Liberibacter asiaticus (CLas) é a mais comum. Devido à ausência de plantas de laranja doce resistentes a essa doença, a busca por plantas transgênicas que apresentem resistência a essa doença têm se intensificado nos últimos anos. Uma estratégia para projetar uma construção gênica visando a CLas é a utilização de promotores floema-específico, pois a CLas coloniza o floema das plantas de citros infectadas. Entretanto, para provar que uma sequência promotora funciona é preciso desafiar a construção gênica na presnça da CLas. Portanto, conduziu-se este trabalho com o objetivo de multiplicar plantas de Citrus sinensis Osbeck (L.) cv. \'Hamlin\' transgênicas contendo o gene uidA sob controle dos promotores floema-específicos Arabidopsis thaliana phloem protein 2 (AtPP2), Citrus phloem protein 2 (CsPP2) e Arabidopsis thaliana sucrose transporter 2 (AtSUC2), inocular com CLas por Diaphorina citri, avaliar a interdependência entre a expressão do transgene (gene uidA) e a concentração de CLas, para poder inferir sobre o controle da expressão dos promotores quando as plantas são inculadas com CLas. Para isso, cinco eventos de transformação de cada construção gênica, contendo apenas uma cópia do transgene foram selecionados, multiplicados e inoculados com CLas por Diaphorina citri, dezoito meses após a inoculação, o DNA e o RNA das plantas foram coletados. Foi realizada análise para verificar a concentração de CLas em todas as plantas inoculadas e a expressão do gene uidA foi realizada em uma linhagem transgênica de cada construção gênica. Com o auxílio da análise de coeficiente de correlação de Person, foi possível classificar qualitativamente a interdependência entre a concentração bacteriana e a expressão gênica. A frequência média de inoculação de CLas por Diaphorina citri foi de 30 %, demostrando que é possível incular CLas via Diaphorina citri. A análise de coeficiente de correlação de Person mostrou que nas construções com promotores AtPP2 e CsPP2 há baixa interdependência entre o controle da expressão gênica e a concentração de CLas. A construção sob controle do promotor AtSUC2 apresentou correlação forte e positiva, mostrando que quanto maior a concentração de CLas maior a expressão do transgene. / Brazil is the largest producer of sweet oranges in the world, however the Brazilian citrus history is marked by successive losses due to pests and diseases attacking orchards. Among the diseases affecting citrus groves, the huanglongbing (HLB) has been highlighted in recent years. The HLB is known in China since 1900, although in Brazil this disease has been present since 2004 and has caused significant losses to citrus industry. This disease is associated with three species of \"Candidatus Liberibacter\", however, in Brazil Candidatus Liberibacter asiaticus species (CLas) is the most common. Due to the absence of sweet orange plants resistant to this disease, the search for transgenic plants with resistance to this disease have intensified in recent years. One strategy to design a genetic construct targeting the CLas includes the use of phloem-specific promoters, because the CLas colonizes the phloem of infected citrus plants. On the other hand, to prove that a promoter sequence works it is necessary to challenge the genetic construct in the presence of CLas. Therefore, we conducted this study with the objectives of multiplying transgenic Citrus sinensis Osbeck (L.) cv. \'Hamlin\' bearing the uidA gene under the control of the phloem-specific promoters Arabidopsis thaliana phloem protein 2 (AtPP2), Citrus phloem protein 2 (CsPP2) and Arabidopsis thaliana sucrose transporter 2 (AtSUC2), inoculate CLas with Diaphorina citri, and evaluate the interdependence between the expression of the transgene (uidA gene) and the concentration of CLas, to infer the promoter expression when the plants are inoculated with CLas. Five events processing of each gene construct, containing only one copy of the transgene, and inoculated with CLas by Diaphorina citri. The DNA and RNA of plants were collected after eighteen months of inoculation. The concentration of CLas in the inoculated plants and the expression of the uidA gene were performed in each transgenic line of each gene construct, with the aid of the analysis of Person correlation coefficient. Thus it was possible to classify qualitatively the interdependence between bacterial concentration and gene expression. The average frequency of CLas inoculation by Diaphorina citri was 30%, demonstrating that it was possible to inoculate CLas via Diaphorina citri. Person correlation coefficient values suggested low interdependence between the control of gene expression and the concentration of CLas in constructions with promoters AtPP2 and CsPP2. The construction under AtSUC2 promoter control showed strong positive correlation, indicating that the higher the concentration of CLas the greater is the transgene expression.
186

Avaliação como probióticos para frangos de corte de Pichia pastoris e Pichia pastoris recombinante contendo o gene da fosfolipase C de Clostridium perfringens / Evaluation of the probiotic properties in broilers of Pichia pastoris and a recombinant Pichia pastoris containing the Clostridium perfringens fosfolipase C gene

STORCH, Otávio Brod 17 November 2008 (has links)
Made available in DSpace on 2014-08-20T14:37:56Z (GMT). No. of bitstreams: 1 dissertacao_otavio_brod.pdf: 418993 bytes, checksum: 32f13d3584050e87ad3df6842a8e5496 (MD5) Previous issue date: 2008-11-17 / Antibiotics used for the last decades as growth promoters for animals, were banned in several countries because of the risk of inducing the appearance of antibiotic resistant bacteria. Probiotics, live microorganisms that benefit health promoting the stability of the gut microbiota, are their most promising substitutes. The objective of this research was to determine the probiotic properties of Pichia pastoris and a recombinant P. pastoris containing the Clostridium perfringens fosfolipase C gene. Ross® P8 female chicks were randomly distributed in four groups of ten each, in three repeats, and fed with a commercial food devoid of antibacterials. Group 1 was fed with un-supplemented food; group 2 was supplemented with 1x106 viable P. pastoris strain KM71H gr-1; group 3 with 1x106 viable recombinant P. pastoris containing the C. perfringens fosfolipase C gene gr-1 and group 4 with 1x106 viable spores of Bacillus cereus var. Toyoi gr-1. Water and food were supplied ad libitum. Weight gain of each animal and food conversion of each group at 49 days of age, were estimated. Individual seroconversions against C. perfringens &#945; toxin at days 1, 10, 20, 30 and 49 were estimated. At the end of the experiment the animals were slaughtered and samples from different organs examined histologically. Mean live weights at 49 days of age were 2.172, 2.228, 2.410 and 2.333 Kg for groups 1, 2, 3 and 4, respectively, different at P<0.05. Mean food conversions were 2.58, 2.41, 2.35 and 2.50 for groups 1, 2, 3 and 4, respectively. Seroconversions at 49 days of age were 1.1, 1.4, 1.5 and 1.3 for groups 1, 2, 3 and 4, respectively, different at P<0.05. Histological alterations were not detected. It was concluded that P. pastoris and recombinant P. pastoris may be used as probiotics for broilers due to their capacity of increasing food efficiency and seroconversion without undesirable effects. / Os antibióticos utilizados como promotores de crescimento nas últimas décadas foram banidos em vários países devido ao risco de induzir o surgimento de bactérias resistentes. Entre as alternativas para sua substituição, os probióticos, suplementos alimentares compostos de microrganismos vivos que beneficiam a saúde do hospedeiro através do equilíbrio da microbiota intestinal, aparecem como a mais plausível. Este trabalho objetivou determinar as propriedades como probiótico da levedura Pichia pastoris e sua variante recombinante contendo o gene da fosfolipase C de Clostridium perfringens. Frangas de um dia de idade da linhagem Ross® P8 foram distribuídas aleatoriamente em quatro grupos de dez animais cada, em três repetições, e alimentadas com ração comercial isenta de antibacterianos. O grupo 1 (Controle) recebeu ração não suplementada, o grupo 2 recebeu a mesma ração suplementada com 1x106 células viáveis gr-1 de P. pastoris cepa KM71H, o grupo 3 ração suplementada com 1x106 gr-1 de células viáveis de P. pastoris recombinante contendo o gene da toxina &#945; de C. perfringens, e o grupo 4 ração suplementada com 1x106 gr-1 de esporos viáveis de Bacillus cereus var. Toyoi. Ração e água foram oferecidos ad libitum. Estimou-se o ganho de peso de cada animal aos 49 dias de idade, e a conversão alimentar de cada grupo. Determinou-se a soroconversão individual por ELISA, utilizando como antígeno a toxina &#945; padrão de C. perfringens, a partir de amostras de sangue coletadas aos 1, 10, 20, 30 e 49 dias de idade. Ao término do experimento os animais foram abatidos e amostras de órgãos submetidos a análise histopatológica. No dia 49, os pesos vivos médios foram 2,172, 2,228, 2,410 e 2,333 kg, significativamente diferentes (P<0,05) ao grupo controle, para os grupos 1, 2, 3 e 4, respectivamente. As conversões alimentares médias foram 2,58, 2,41, 2,35 e 2,5 para os grupos 1, 2, 3 e 4, respectivamente. As soroconversões ao dia 49 foram 1,1, 1,4, 1,5 e 1,3 para os grupos 1, 2, 3 e 4, respectivamente, significativamente diferentes (P<0,05) ao grupo controle. Nos estudos histopatológicos não foram encontradas alterações. Concluiu-se que P. pastoris e P. pastoris recombinante podem ser utilizadas como probiótico em frangos de corte por aumentar a eficiência alimentar e a soroconversão, sem apresentar contraindicações.
187

Biochemical characterization of ArsI: a novel C-As lyase for degradation of environmental organoarsenicals

Pawitwar, Shashank Suryakant 26 June 2017 (has links)
Organoarsenicals such as methylarsenical methylarsenate (MAs(V)) and aromatic arsenicals including roxarsone (4-hydroxy-3-nitrophenylarsenate or Rox(V)) have been extensively used as an herbicide and growth enhancers in animal husbandry, respectively. They undergo environmental degradation to more toxic inorganic arsenite (As(III)) that contaminates crops and drinking water. We previously identified a bacterial gene (arsI) responsible for aerobic MAs(III) demethylation. The gene product, ArsI, is a Fe(II)-dependent extradiol dioxygenase that cleaves the carbon-arsenic (C-As) bond in MAs(III) and trivalent aromatic arsenicals. The objective of this study was to elucidate the ArsI mechanism. Using isothermal titration calorimetry, we determined the dissociation constants (Kd) and ligand-to-protein stoichiometries (N) of ArsI for Fe(II), MAs(III) and aromatic phenyl arsenite. Using a combination of methods including chemical modification, site-directed mutagenesis, and fluorescent spectroscopy, we demonstrated that amino acid residues predicted to participate in Fe(II)-binding (His5-His62-Glu115) and substrate binding (Cys96-Cys97) are all involved in catalysis. Finally, the products of Rox(III) degradation were identified as As(III) and 4-hydroxy-2-nitrophenol, demonstrating that ArsI is a dioxygenase that incorporates one oxygen atom from dioxygen into the carbon and the other to the arsenic to catalyze the cleavage of the C-As bond. These results augment our understanding of the mechanism of this novel C-As lyase.
188

Structural Feature of Prokaryotic Promoters and their Role in Gene Expression

Aditya Kumar, * January 2015 (has links) (PDF)
Transcription initiation is an important step in the process of gene regulation in prokaryotes. Promoters are stretches of DNA sequence that are present in the upstream region of transcription start sites (TSSs), where RNA polymerase and other transcription factors bind to initiate transcription. Recent advancement in sequencing technologies has resulted in huge amount of raw data in the form of whole genome sequences. This sequence data has to be annotated, in order to identify coding, non-coding and regulatory regions. Computational tools are useful for a quick and fairly reliable annotation of many genome sequences. Promoter prediction is an important step in genome annotation process which is needed, not only for the validation of predicted genes, but also for the identification of novel genes, especially those coding for non-coding RNA, which are missed by gene prediction programs. DNA sequence dependent structural properties such as DNA duplex stability, bendability and intrinsic curvature have been found to be associated with promoter regions in all domains of life. The work presented in this thesis focuses on the analysis of these structural features in the promoter regions of published prokaryotic transcriptome data. Furthermore, promoters were predicted using these structural features and their role in gene expression were studied. The organization of thesis is as follows. An overview of transcription machinery of prokaryotes, promoter architecture, available promoter prediction programs and sequence dependent structural features is presented in chapter 1. Chapter 2 describes the datasets and methods used in entire study. Structural features of promoters associated with primary and operon TSSs of H.pylori26695 genes and their orthologs (chapter 3) Promoter regions in genomic sequences from all domains of life show similar trends in their structural properties such as stability, bendability, curvature. This chapter dis-cuss the DNA duplex stability and bendability of various classes of promoter regions (based on the identification of different classes of transcription start sites, viz. primary, secondary, internal, operon TSSs etc, in transcriptome study) of Helicobacter pylori 26695 strain. It is found that the primary TSS and operon associated TSS promoters show significantly strong structural features in their promoter regions. DNA free energy based promoter prediction tool PromPredict has been used to annotate promoters of different classes and very high recall values (80%) are obtained for primary TSS. Orthologous genes from 10 different strains of H. pylori show conservation of structural properties in promoter regions as well as coding regions. PromPredict annotates promoters of orthologous genes with very high recall and precision values. DNA duplex stability of promoter region is conserved in the orthologous genes in 10 different strains of Helicobacter pylori genome. Sequence dependent structural features of promoters in prokaryotic transcriptome (chapter 4) Next-generation sequencing studies have revealed that a wide range of transcripts such as primary, internal, antisense and non-coding RNA, are present in the prokaryotic transcriptome and a large fraction of them are functionally involved in various regulatory activities. Identification of promoters associated with different transcripts is important for characterization of transcriptome. The current chapter discusses DNA sequence dependent structural properties like stability, bendability and curvature in the promoter region of six different prokaryotic transcriptomes (Helicobacter pylori, Anabaena, Synechocystis, Escherichia coli, Salmonella and Klebsiella). Using these structural features, promoters associated with different category of transcripts were predicted, which constitute an integral part of the transcriptome. Promoter annotation using structural features is fairly accurate and reliable as compared to motif-based approach since different category of transcripts show poor sequence conservation in the promoter region. Most importantly, it is universal in nature unlike sequence-based approach that is generally organism specific. Role of sequence dependent structural properties in gene expression in prokaryotes (chapter 5) DNA duplex stability, bendability and intrinsic curvature play crucial roles in the process of transcription initiation. Hence, in order to understand the relationship be-tween these structural features and gene expression, the relative differences in stability, bendability and curvature in the promoter regions of high and low expressed genes were studied. It is found that these features are relatively accentuated in the promoter regions associated with high gene expression as compared to low gene expression. Promoter regions associated with high gene expression are annotated more reliably using DNA structural features, compared to those for low gene expression. Sequence dependent structural properties in the promoter region of essential and non-essential genes of the prokaryotes (chapter 6) Essential genes are the minimal possible set of genes required for the survival of organism. These sets of genes can be identified by experiments such as single gene deletion and transposon mediated inactivation. Here, the analysis of DNA duplex stability and bendability in the promoter regions of essential and nonessential genes of prokaryotes is reported. It is found that the average free energy and bendability pro-files are distinct in the promoters regions of essential and nonessential genes. Whole genome promoter predictions using in-house program, PromPredict, for essential and nonessential genes has also been carried out. Chapter 7 present the summary and conclusion of the entire thesis work followed by future perspectives in the field. Optimization of PromPredict algorithm and updating PromBase with newly sequenced genomes (Appendix A) PromPredict is an in-house program, which is based on the relative stability of the DNA in flanking regions. It was found to perform well in predicting promoters across all organisms. In previous studies, it was observed that for organisms having low genomic GC content (<35%), promoter prediction resulted in low precision values, which indicates higher false positive rate. Threshold values of PromPredict algorithm were re-vised in order to optimize the algorithm with low false positive rate. PromBase is a comparative genomics database of microbial genomes. It stores different genomic and structural properties of the microbial genomes. It also displays the predictions obtained from PromPredict in a graphical as well as tabular format. Newly sequenced genomes were downloaded from NCBI and processed using in-house programs and added to the mysql database (back end of the PromBase). Stability profiles for predictions were also added for the RNA coding genes, earlier only profiles for protein coding genes were displayed. Comparative genomics of asymmetric gene orientation in prokaryotes (Appendix B) Transcription proceeds in 5’ to 3’ direction on the template strand, hence it provides directionality. Prokaryotic genomes show asymmetry in gene orientation on leading and lagging strands. The different phyla of prokaryotes were analyzed in terms of asymmetry in gene orientation. It is found that organisms belonging to a particular phyla known as “Firmicutes”, show high asymmetry in gene orientation, which are known to have different DNA polymerase systems for replication.
189

Onkogenní promotor c-myc jako cíl pro nový typ heterocyklických dikationtů stabilizujících G-kvadruplex. / The promoter of c-myc oncogene as a target for a novel type of heterocyclic cations stabilizing G-quadruplex.

Pohlová, Lenka January 2015 (has links)
Targeting oncogene promoters: a novel heterocyclic cations as G-quadruplex stabilizing ligands Lenka Pohlová Abstract: The diploma thesis studies an effect of newly synthesized group of compounds - helquats - on the expression of c-myc as a major player in malignant transformation and tumorigenesis via the stabilization of G-quadruplex in c-myc promotor. The G-quadruplex c-myc stabilization ability was tested for 101 helquats using dual luciferase reporter assay. The G-quadruplex c-myc stabilization ability was found for 13 helquats by this method. 8 successful helquats was selected by a comparison of the results from dual luciferase reporter assay and FRET melting assay. Effect on cell viability of tumor (HeLa S3) and non-tumor (HUVEC) cell lines was evaluated for these 8 helquats. Three of them exhibited cytotoxic effect on tumor cells but no effect was observed on viability of non-tumor cells. Moreover, an effect of these 3 helquats on c-myc expression on both mRNA and protein level, where significant effect on c-myc mRNA expression was not found for most of incubation periods. The 30% decrease in mRNA level was observed only for 24 hours incubation period for two helquats (LS702 and MJ656). The decrease in the expression on protein level was observed for all tested helquats, and helquat LS702 had the...
190

Les SARMs (Selective Androgen Receptor Modulators) : une nouvelle famille d'agents anabolisants. Etude des effets zootechniques associés et développement de stratégies analytiques visant la mise en évidence de leur utilisation chez le jeune bovin / SARMs (Selective Androgen Receptor Modulators) : a new class of anabolic agents. Zootechnical effects and analytical strategies to detect their administration in bovines

Cesbron, Noura 04 June 2017 (has links)
De nouveaux composés anabolisants sont devenus accessibles via Internet : les modulateurs spécifiques des récepteurs androgènes (SARMs) actuellement développés pour le traitement des pertes musculaires. L’Ostarine® (MK-2866, GTX-024, enobosarm) en particulier, exerce ses effets sur les muscles squelettiques et ne présente pas d'activité androgénique. Sur la base de son mécanisme d’action et des résultats cliniques préliminaires, ce produit pourrait être utilisé comme promoteur de croissance en élevage bovin. Dans ce contexte, les objectifs de la thèse sont de valider des outils permettant de décrire les effets zootechniques pouvant être induits par l’administration orale d'enobosarm à des bovins et de développer des stratégies analytiques dédiées à la mise en évidence de son utilisation frauduleuse. En comparant animaux contrôles et animaux traités avec l'enobosarm, aucun effet morphologique n'a été mis en évidence en termes de croissance ou de conformation. Il a été ensuite démontré que l'enobosarm et ses principaux métabolites de phase II sont éliminés dans les urines et les fèces à des concentrations permettant leur détection par des techniques analytiques impliquant le couplage chromatographie en phase liquide et spectrométrie de masse. Enfin, une stratégie de type métabolomique conduite sur matrices urinaire et fécale a conduit à la description d’empreintes spécifiques et discriminantes pouvant signer l’administration d'enobosarm. Ce travail de recherche pluridisciplinaire contribue à générer des connaissances sur une nouvelle classe d'anabolisants, permettant par extension de contribuer à garantir au consommateur une sécurité chimique accrue des denrées d’origine animale. / New compounds with anabolic properties have recently become accessible via Internet-based suppliers: selective androgens receptor modulators (SARMs) currently developed for the treatment of chronic diseases with wasting muscle. Ostarine® (MK-2866, GTX-024, enobosarm), in particular, exerts its anabolic effects exclusively on the skeletal muscles and has no androgenic activity. Based on its mechanism of action and clinical preliminary results, this product could potentially be used as a growth promoter in cattle. In this context, the aims of this thesis are to validate tools allowing to describe the zootechnical effects that may be induced by an oral administration of enobosarm in calves and to develop analytical strategies dedicated to highlight its fraudulent use. Following a comparison between control animals and enobosarm treated animals, no morphological effect was visible and measurable in terms of growth and conformation. It was then demonstrated that enobosarm and its main phase II metabolites are eliminated in urine and feces at concentrations allowing their detection with analytical techniques using a liquid chromatography-mass spectrometry coupling. Finally, a metabolomics approach on urine and fecal matrices led to the description of specific and discriminant fingerprints signaling the administration of enobosarm. This multidisciplinary research work helps to generate knowledge on a new class of anabolic substance and therefore contributes to guarantee a more chemically-safe food of animal origin to the consumer.

Page generated in 0.1002 seconds