• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 868
  • 456
  • 401
  • 97
  • 68
  • 32
  • 31
  • 31
  • 30
  • 22
  • 14
  • 10
  • 8
  • 7
  • 7
  • Tagged with
  • 2367
  • 295
  • 243
  • 204
  • 149
  • 144
  • 136
  • 134
  • 126
  • 122
  • 108
  • 102
  • 99
  • 91
  • 90
  • 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.
871

Parâmetros periodontais clínicos e microbiológicos de mulheres na gestação e no pós-parto

Machado, Fernanda Campos 28 August 2012 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-01T18:12:17Z No. of bitstreams: 1 fernandacamposmachado.pdf: 8104440 bytes, checksum: c6b4f12f1beb42cb6f9fe523172990b2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T16:05:52Z (GMT) No. of bitstreams: 1 fernandacamposmachado.pdf: 8104440 bytes, checksum: c6b4f12f1beb42cb6f9fe523172990b2 (MD5) / Made available in DSpace on 2016-07-13T16:05:52Z (GMT). No. of bitstreams: 1 fernandacamposmachado.pdf: 8104440 bytes, checksum: c6b4f12f1beb42cb6f9fe523172990b2 (MD5) Previous issue date: 2012-08-28 / Os níveis de estrógeno e progesterona, necessários à manutenção da gestação, podem contribuir para a maior suscetibilidade ao aparecimento de determinados micro-organismos periodontopatogênicos e consequente desenvolvimento da doença periodontal em gestantes. O objetivo desta investigação foi avaliar os parâmetros periodontais clínicos e microbiológicos de mulheres na gestação e no pós-parto. Os achados das gestantes foram comparados com os de um grupo controle de não gestantes. Este estudo longitudinal prospectivo, com desenho transversal paralelo, incluiu 31 mulheres no segundo trimestre da gestação, acompanhadas em dois momentos após o parto (48 horas e oito semanas) e 20 não gestantes na mesma faixa etária. O exame clínico determinou a condição periodontal das mulheres por meio dos seguintes indicadores: sangramento à sondagem (SS), presença de cálculo (PC), profundidade de sondagem (PS) e nível clínico de inserção (NCI). Amostras de biofilme subgengival e saliva foram coletadas e a identificação e quantificação de Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Campylobacter rectus, Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatum, Prevotella intermedia e Prevotella nigrescens foram realizadas pela técnica da hibridização in situ fluorescente (FISH). O teste U de Mann-Whitney foi utilizado para a comparação clínica e microbiológica entre os grupos de gestantes e não gestantes. Para a comparação intragrupo, foi empregado o teste de Friedman, seguido pelo teste de Wicoxon. Os grupos de gestantes e não gestantes apresentaram condições periodontais semelhantes. Em relação à microbiota verificada no biofilme subgengival, não foi encontrada diferença significativa entre as mulheres no segundo trimestre de gestação e as não gestantes. Em relação à microbiota salivar, foi observada maior abundância de P. intermedia nas gestantes, em comparação com as não gestantes. Na comparação intragrupo dos parâmetros clínicos, o teste de Friedman demonstrou diferença estatisticamente significativa em relação à PS=4-5 mm, não confirmada pelo teste de Wilcoxon. Em relação aos parâmetros microbiológicos, no biofilme subgengival foi verificado que os números de P. nigrescens diminuíram ao longo dos três momentos avaliados,que números significativamente mais altos de C. rectus foram encontrados durante o segundo trimestre, em comparação com o exame de oito 8 semanas após o parto, e que níveis significativamente mais altos de P. intermedia foram observados 48 horas após o parto, em comparação com o exame de oito semanas após o parto. Na saliva, foi verificada uma redução significativa de P. intermedia e P. nigrescens ao longo do acompanhamento longitudinal, com os maiores valores encontrados no segundo trimestre da gestação. Em conclusão, os resultados confirmaram a hipótese de que existe uma alteração na microbiota durante a gestação, pelo menos para P. nigrescens, P. intermedia e C. rectus, embora pequena diferença tenha sido verificada em relação aos parâmetros clínicos. / The levels of estrogen and progesterone necessary for maintenance of pregnancy may contribute to increased susceptibility to the occurrence of certain periodontopathogenic bacteria and subsequent development of periodontal disease in pregnant women. The aim of this study was to evaluate clinical and microbiological parameters in women during pregnancy and post-partum. The findings of the pregnant women were compared with a control group of non-pregnant ones. This longitudinal study, with a cross-sectional parallel design, included 31 women at second trimester of their pregnancy, examined one time during pregnancy and twice during post-partum (48h and 8 weeks after the delivery), and 20 non-pregnant women within the same age range. Bleeding on probing (BOP), presence de calculus (PC), probing depth (PD) and clinical attachment level (CAL) were recorded. Bacterial samples from the subgingival biofilm and saliva were collected and the fluorescence in situ hybridization (FISH) technique identified the presence and number of Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Campylobacter rectus, Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatum, Prevotella intermedia and Prevotella nigrescens. The Mann-Whitney U-test was applied to compare clinical and microbiological data from pregnant and non-pregnant women. The Friedman and Wilcoxon tests were used for intra-group comparisons. Pregnant and non-pregnant women showed similar periodontal conditions. Regarding the subgingival microbiota, no significant difference was found among women in the second trimester of pregnancy and nonpregnant women. Regarding the salivary microbiota, it was observed higher abundance of P. intermedia in pregnant compared with non-pregnant women. In intra-group comparison, for clinical parameters, Friedman test showed significant difference concerning PD = 4-5 mm, not confirmed by the Wilcoxon test. Regarding the microbiological parameters, in the subgingival biofilm it was found that numbers of P. nigrescens decreased among the three periods analyzed, increased bacterial counts were found for C. rectus from the second trimester to 48h after the delivery, as well as for P. intermedia from 48h to 8 weeks post-partum. In saliva, there was a significant reduction of P. intermedia and P. nigrescens among the longitudinal follow-up, with the highest values found in the second trimester of pregnancy. In 10 conclusion, the results confirm the hypothesis that there is a change in the microbiota during pregnancy, at least for P. nigrescens, P. intermedia and C. rectus, although little difference was observed in relation to clinical parameters.
872

Mapeamento cromossômico de DNA satélite e comportamento meiótico no complexo Poliploide Lippia alba (Mill.) N. E. Br.

Reis, Aryane Campos 03 March 2017 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-18T10:44:31Z No. of bitstreams: 1 aryanecamposreis.pdf: 2882567 bytes, checksum: 1a13439227f336c21faf2248369b319c (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: on 2017-08-18T12:29:10Z (GMT) / Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-18T13:17:38Z No. of bitstreams: 1 aryanecamposreis.pdf: 2882567 bytes, checksum: 1a13439227f336c21faf2248369b319c (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: on 2017-08-24T11:27:59Z (GMT) / Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-24T15:19:15Z No. of bitstreams: 0 / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-30T14:32:15Z (GMT) No. of bitstreams: 0 / Made available in DSpace on 2017-08-30T14:32:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-03-03 / Lippia alba (Verbenaceae), é uma espécie herbácea tropical com grande plasticidade fenotípica e genômica, amplamente utilizada na medicina popular. Recentemente, a espécie foi descrita como um novo complexo autopoliploide contendo cinco números cromossômicos (2x=30, 2x=30+8, 3x=45, 4x=60 e 6x=90), e esforços têm sido feitos a fim de entender sua origem e evolução. No presente trabalho, foram descritos perfis cariotípicos mais detalhados da espécie, por meio de mapeamento cromossômico utilizando sondas espécie-específicas e análises do comportamento meiótico e de viabilidade polínica. A partir do sequenciamento genômico de baixa cobertura (IIlumina MiSeq), foram desenvolvidos novos marcadores citogenéticos (denominados CL66 e CL98) os quais foram utilizados para o mapeamento cromossômico em acessos representando os cinco citótipos do complexo. Para a análise meiótica, seis estágios da divisão (metáfase I; anáfase I + telófase I; metáfase II; anáfase II + telófase II) foram quantificados, e aproximadamente, 100 células foram avaliadas para cada estágio. Os mesmos acessos foram avaliados quanto à viabilidade polínica (1.000 grãos de pólen foram quantificados para cada indivíduo). Os resultados da Hibridização Fluorescente in situ (FISH) revelaram que ambas as repetições satélite estão localizadas na porção terminal dos cromossomos. Em geral, a repetição CL98 mostrou um padrão uniforme nos diferentes acessos. Foram observados dois, três, quatro e seis cromossomos marcados em diploides, triploides, tetraploides e hexaploide, respectivamente, revelando que o número de cromossomos marcados variou proporcionalmente, de acordo com o nível de ploidia do acesso. Por outro lado, a repetição CL66 apresentou-se polimórfica. Variações foram observadas entre os acessos, principalmente, entre os indivíduos diploides. Com relação às análises meióticas, alto percentual de irregularidade foi observado nos citótipos poliploides. Entretanto, alguns acessos 2x também mostraram consideráveis erros durante a microsporogênese. Entre as irregularidades encontradas, destacam-se: pareamento cromossômico anormal; segregação cromossômica desigual; cromossomos perdidos; tríades e políades. Os resultados da viabilidade polínica corroboraram os dados da meiose. A partir do conjunto de dados obtidos foi possível concluir que 1) a metodologia para o desenvolvimento de marcadores cromossômicos específicos para L. alba mostrou-se eficiente; 2) as repetições satélite exibiram diferentes comportamentos (estável e dinâmico) no genoma de L. alba; 3) a ocorrência de microsporogênese irregular em diploides, associada à viabilidade polínica, sugerem que os acessos 2x sejam elementos importantes na formação do complexo poliploide e 4) a ampla variação cariotípica observada na espécie pode ser consequência de múltiplos e independentes eventos de duplicação genômica, aliado a rearranjos cromossômicos. Possivelmente, L. alba encontra-se em processo de estabilização do seu cariótipo tornando a espécie, um importante modelo para estudos de poliploides naturais nos trópicos. / Lippia alba (Verbenaceae) is a tropical aromatic shrub with extensive phenotypical and genomic plasticity widely used in traditional medicine. Recently, the species was described as a new natural autopolyploid complex with five distinct chromosome numbers (2x=30, 2x=30+8, 3x=45, 4x=60 and 6x=90). Strides have been done in order to understand the cytotypes origin and species evolution. In this study, a detailed karyotype of L. alba using Fluorescence in situ Hybridization (FISH) with species-specific probes was described. We also report the meiosis behavior and pollen viability in sixty accessions. Using massive parallel sequencing (IIlumina MiSeq platform) new cytogenetic landmarks (CL66 and CL98) were chosen for probing all cytotypes described for the species. For meiotic analysis, the percentage of abnormalities was quantified, evaluating around 100 cells in six stages (metaphase I; anaphase I + telophase I; metaphase II; anaphase II + telophase II). Around 1,000 pollen per accession were used to estimate pollen viability. FISH results revealed that both satDNA arrays are located preferentially on terminal sites of the chromosomes. In general, the CL98 repeat showed a uniform pattern in different accessions. We observed 2, 3, 4, and 6 marked chromosomes respectively in diploid, triploid, tetraploid and hexaploid accessions revealing that the number of depicted chromosomes varied proportionally according to the ploidy level. On the other hand, the CL66 repeat was polymorphic. Great variations were observed among the accessions mainly within the diploids. In general, the meiotic analysis revealed higher index of abnormalities in polyploid cytotypes. However, some 2x accessions also showed considerable irregularities during the microsporogenesis. Desynapsis, unequal segregation, lost chromosomes, triads and polyads were the most common irregularities observed. Pollen viability analysis corroborated the meiosis data. It was possible to conclude that 1) the development of specific landmarks for L. alba was efficient; 2) the karyotypic profiles of both satDNA revealed different behavior; 3) microsporogenesis analysis and pollen viability of 2x accessions suggest that diploids are the key point for the origin of the polyploid complex and 4) independent and multiples events of genome duplication associated to chromosome rearrangements may have generated great karyotypic variation in the species. L. alba karyotype is possibly under stabilization process making the species an important model to study natural polyploids in the tropics.
873

Caracterização de recursos genéticos de Butia odorata no Bioma Pampa / Characterization of genetic resources of Butia odorata in Pampa Biome

Mistura, Claudete Clarice 02 May 2013 (has links)
Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-09-28T13:25:02Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) TESE 2013 - CLAUDETE CLARICE MISTURA.pdf: 1301201 bytes, checksum: 9fd5c6211a9d758b88134b60bd5a7d81 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-09-28T18:48:24Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) TESE 2013 - CLAUDETE CLARICE MISTURA.pdf: 1301201 bytes, checksum: 9fd5c6211a9d758b88134b60bd5a7d81 (MD5) / Made available in DSpace on 2016-09-28T18:48:24Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) TESE 2013 - CLAUDETE CLARICE MISTURA.pdf: 1301201 bytes, checksum: 9fd5c6211a9d758b88134b60bd5a7d81 (MD5) Previous issue date: 2013-05-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Butia odorata (Barb. Rodr.) Noblick é uma das 266 espécies de palmeiras que ocorrem no Brasil. Produz frutos que são utilizados na alimentação, tanto in natura como processados (na forma de geleias, sorvetes, sucos e licores). Apresentam elevado potencial energético, devido aos óleos existentes nas sementes. As folhas da planta, ricas em fibras, são usadas no artesanato para a confecção de objetos decorativos e utilitários. Contudo, as populações naturais sofrem intensa ação antrópica, principalmente em consequência do uso das terras para a agricultura e a expansão urbana. Além disso, mesmo em algumas áreas remanescentes, a pressão de pastoreio do gado restringe de modo expressivo a regeneração, restando somente indivíduos adultos. Com o objetivo geral de contribuir para o conhecimento relacionado aos recursos genéticos de B. odorata no Bioma Pampa, foram desenvolvidas atividades de campo na Fazenda São Miguel (Tapes, RS), análises morfológicas análises moleculares nos laboratórios de Recursos Genéticos e de Biologia Molecular da Embrapa Clima Temperado (Pelotas, RS), sistematização dos descritores morfológicos mínimos no Bioversity International (Roma/Maccarese, Itália). Os resultados são apresentados em quatro artigos. No primeiro artigo, com o objetivo de avaliar a transposição de marcadores microssatélites desenvolvidos para o genoma de coco em butiá, foram testados 50 pares de primers desenvolvidos para coco em 30 indivíduos de butiá coletados em três áreas distintas em uma população natural. Dos 50 pares de primers avaliados, 28 amplificaram, sendo que oito deles apresentaram bandas inespecíficas e não foram considerados na análise estatística. A transferibilidade dos primers testados foi de 40%, indicando que esses marcadores microssatélites desenvolvidos para o genoma de coco podem ser utilizados com sucesso para análises genéticas em butiá. No segundo artigo, com objetivo de avaliar a estrutura genética de uma população natural de B. odorata, foram avaliados 303 indivíduos, utilizando 20 pares de primers SSR. Foi constatada grande variabilidade genética, com maior variação molecular entre os indivíduos dentro de cada área do que entre aqueles de áreas distintas. A heterozigosidade observada, menor do que a esperada, indica a ocorrência de endogamia. As plantas da terceira área avaliada apresentam estruturação genética, devido à ação de fluxo gênico e/ou de deriva genética. O terceiro artigo discute a variabilidade de B.odorata com base em comparações entre o conhecimento científico e o conhecimento popular. Foram elencados como descritores morfológicos importantes para a caracterização do germoplasma as seguintes características: hábito das folhas, circunferência do caule, cor da folha, cor das flores masculinas, número de cachos por planta, cor do fruto maduro, formato do fruto, presença de fibras na polpa, diâmetro do fruto, época de floração e frutificação. Por sua vez, os agricultores costumam usar um menor número de características para distinguir as plantas: tamanho do fruto, número de cachos por planta, presença de fibras na polpa, sabor e cor dos frutos. Os resultados obtidos no terceiro artigo foram utilizados para a elaboração do quarto artigo, que consiste na lista dos descritores morfológicos mínimos para a caracterização do germoplasma de B. odorata. / Butia odorata (Barb. Rodr.) Noblick is one of 266 palm species that occur in Brazil. The plants produces fruits that are used for food, both fresh and processed (as jellies, ice creams, juices and liqueurs). It has high potential as energy source due to the oils cointained in the seeds. The leaves are rich in fibers, and are used in the crafting of decorative and utilitarian objects. However, natural populations suffer intense human activity, mainly as a result of land use for agriculture and urban expansion. Moreover, even in certain areas remaining, pressure by grazing cattle has restricted the regeneration, leaving only adult plants. With the aim of contributing to the knowledge related to genetic resources of B. odorata in Pampa Biome, field activities were developed at São Miguel Farm (Tapes, RS), morphological and molecular analyzes were done in Genetic Resources and Molecular Biology labs of Embrapa Temperate Agriculture (Pelotas, RS), and a morphological descriptors minimum list was developed at Bioversity International (Rome / Maccarese, Italy). The results are presented in four articles. The first article aimed to evaluate the implementation of microsatellite markers developed for coconut in the butiá. A total of 50 primer pairs in 30 individuals of butiá collected in three separate areas were tested in a natural population. Among 50 primer pairs evaluated, 28 amplified, and eight of them showed unspecific bands and were not considered in the statistical analysis. The transferability of primers tested was 40%, indicating that these microsatellite markers developed for the coconut genome can be successfully used for genetic analysis in pindo palm. The objective of the second article was to evaluate the genetic structure of a natural population of B. odorata. We evaluated 303 plants using 20 pairs of SSR primers. High genetic variability was observed, with higher molecular variation among individuals within each area than among those from different areas. The observed heterozygosity was lower than expected, indicating the occurrence of inbreeding. The third area of plants have genetic structure due to the action of gene flow and / or genetic drift. The third article discusses the variability of B. odorata based on comparisons between scientific and popular. As morphological descriptors important for the characterization of germplasm were the following characteristics: habit of the leaves, stem circumference, leaf color, color of male flowers, number of bunches per plant, mature fruit color, fruit shape, presence of fibers in the pulp, fruit diameter, flowering and fruiting time. In turn, farmers use usually a lower number of traits to distinguish different plants: fruit size, number of bunches per plant, presence of fibers in the pulp, flavor and color of the fruit. The results presented in the third article were used for the preparation of the fourth article, which is the minimum list of morphological descriptors for the characterization of germplasm of B. odorata.
874

Impact radiatif des aérosols de haute altitude / Radiative impact of aerosols at high altitude

Chauvigné, Aurélien 01 December 2016 (has links)
La présence des particules d’aérosols dans l’atmosphère influencent le bilan radiatif de notre planète et ainsi son équilibre climatique. Selon les différents mécanismes d’émission et processus de transports atmosphériques, les aérosols peuvent être entrainés dans la troposphère libre et ainsi y résider pendant plusieurs semaines. Les contributions optiques et radiatives des aérosols de troposphère libre par rapport à celles de la colonne atmosphérique sont encore mal évaluées du fait de la difficulté d’accès et du manque de mesures sur de longues périodes. Ces travaux de thèse se sont donc appuyés sur deux sites d’altitude présentant des topographies adéquates pour l’analyse des aérosols de troposphère libre : le site ACTRIS/GAW du puy de Dôme (PUY, 1 465 m, France) et le site ACTRIS/GAW de Chacaltaya (CHC, 5 240 m, Bolivie). Ces deux sites disposent d’un large jeu de données in-situ et de télédétection. Les résultats montrent ainsi l’importance de la prise en compte de la structure verticale de l’atmosphère et de l’effet de l’humidité sur les propriétés des aérosols dans l’analyse des mesures. Pour la première fois à notre connaissance, l’utilisation de ces techniques instrumentales depuis la station de mesures météorologiques la plus haute du monde (Chacaltaya) a permis d’établir les propriétés optiques des aérosols dans cette région largement influencée par la ville de La Paz et par les émissions de la forêt amazonienne. Les résultats montrent que l’influence des feux de forêt amazoniens à la fin de la saison sèche peut accroitre les propriétés optiques de l’aérosol à cette altitude d’un facteur de 3,5 en moyenne et celles de la troposphère libre de 28 à 80%. La station est d’ailleurs régulièrement influencée par les conditions de la troposphère libre (30% du temps en journée et 60% la nuit). Ce manuscrit présente également des méthodes originales pour la détermination des contributions optiques et radiatives des aérosols de troposphère libre avec l’utilisation conjointe des mesures in-situ, photométriques et LIDAR. Les résultats établissent ainsi des contributions optiques de la troposphère libre au-dessus du puy de Dôme variant de 20%en hiver à 80% en été en moyenne. L’utilisation du modèle de transfert radiatif SBDART permet d’évaluer les contributions radiatives correspondantes qui oscillent entre 13 et 40% pour les courtes longueurs d’onde, soit des forçages radiatifs de -1 W.m-2 à -10 W.m-2. Les différentes sources d’aérosols en surface influencent donc fortement la composition de la troposphère libre, qu’il est alors nécessaire de prendre en compte dans le bilan radiatif global de notre planète. / Atmospheric aerosols impact the earth radiative budget and its climate. Depending on their emission mechanisms and atmospheric transport processes, aerosols can be injected into the free tropophere where their lifetime is increased to up to several weeks. Optical and radiative properties of free tropospheric aerosols are still poorly known because of the difficulties to access high altitudes over long periods of time. The present work is based on two high altitude sites measurements: the ACTRIS/GAW station of puy de Dôme (PUY, 1 465 m, France) and the ACTRIS/GAW station of Chacaltaya (CHC, 5 240 m, Bolivia). These two sites are equipped with a unique set of both in-situ and remote sensing measurements. Results first show the importance of taking into account the vertical atmospheric structure and the hygroscopic properties of aerosols when combining in situ and remote sensing measurements. Measurements from the highest atmospheric station in the world (Chacaltaya), provide for the first time to our knowledge, the aerosol optical properties from this region of the world, segregated into mixing layer aerosols and free tropospheric aerosols.The site is both influenced by anthropogenic emissions from the nearby city, La Paz and pristine emissions from the Amazonian forest. From these measurements, we observe that biomass burning emissions can increase column aerosol optical properties by an average factor of 3,5 and the free tropospheric aerosol optical properties between 28 and 80%. The station is regularly influenced by free tropospheric conditions (30% of the time during daytime and 60% during nighttime). This manuscript is also presenting original methods for retrieving the optical and radiative aerosol contributions from the free tropospheric layer to the total atmospheric column using a combination of in-situ, photometric and LIDAR measurements. Results show that free tropospheric contributions above puy de Dôme station vary from 20% during winter to 80% during summer. The use of the radiative transfer model SBDART allows to evaluate the corresponding shortwave radiative contributions of free tropospheric aerosols between 13 and 40% (between -1 and -10 W.m-2). Thus, the different surface aerosol emissions influence significantly the free tropospheric composition which is essential for radiative budget determination.
875

Conception et réalisation de capteurs biomimétiques à base de polymères à empreintes moléculaires à transduction électrochimique / Design and implementation of biomimetic electrochemical sensors transduction based on molecularly imprinted polymers

Betatache, Amina 13 December 2013 (has links)
Les biocapteurs sont des moyens d'analyse en plein essor à la fois rapides, sélectifs et peu coûteux, applicables à des domaines très variés (environnement, santé, agroalimentaire…). La capacité de reconnaissance moléculaire extraordinaire de biomolécules telles que les enzymes ou les anticorps a été exploitée avec succès pour la réalisation de nombreux biocapteurs. Cependant, l'inconvénient majeur de ces récepteurs biologiques est qu'ils sont difficiles à produire et fragiles. Une manière de surmonter ces inconvénients consiste à les remplacer par des récepteurs artificiels présentant des propriétés de reconnaissance similaires. Parmi les matériaux biomimétiques prometteurs figurent les polymères à empreintes moléculaires (MIPs). Dans ce travail, nous nous sommes intéressés au développement de deux capteurs biomimétiques impédimétriques, le premier basé sur l'utilisation de poly(éthylène co-alcool vinylique) imprimé pour la détection de la créatinine et le deuxième sur des MIPs de polyméthacrylate pour la détection de la testostérone. Dans le premier cas, le polymère imprimé a été produit et déposé à la surface d'électrodes en or, soit par drop-coating, soit sous forme de nanofibres par la technique d'électrofilage. Dans le deuxième, le MIP a été synthétisé par polymérisation radicalaire de l'acide méthacrylique en présence d'éthylèneglycol diméthacrylate (réticulant), d'initiateur et de testostérone en utilisant la méthode du « grafting from » qui consiste à greffer d'abord l'initiateur sur la surface du transducteur mais pour la polymérisation on a utilisé deux approches (spin-coating d'une solution de prépolymérisation sur la surface du transducteur ou l'immersion de ce dernier dans la solution de monomère plus testostérone) suivie de l'exposition à une source d'energie pour effectuer la polymérisation. Les performances des capteurs (limite de détection, sélectivité, reproductibilité) ont ensuite été évaluées / Biosensors are rapid, selective and low-cost analytical devices of growing interest for a wide range of application fields (e.g. environment, food, health). The extraordinary molecular recognition capabilities of sensing biomolecules such as enzymes and antibodies have been successfully exploited in the elaboration of a number of biosensors. However, these biorecognition elements are often produced via complex and costful protocols and require specific handling conditions because of their poor stability. To circumvent these limitations, artificial receptors of similar recognition properties are now proposed as alternatives to natural receptors in sensor technology. Molecular imprinted polymers are among the most promising biomimetic materials reported. In this work, we developed two impedimetric biomimetic sensors. The first one is based on imprinted poly(ethylene co-vinyl alcohol) for creatinine detection and the second on polymethacrylate MIPs for testosterone analysis. In the first case, MIP was produced and deposited onto gold microelectrodes, either by spin-coating of a pre-polymerization solution, or by electrospinning. In the second case, MIPs were synthetized by photopolymerization of methacrylic acid in presence of ethyleneglycoldimethacrylate (cross-linker), an azo-initiator and testosterone as template using the “grafting from” method in which the initiator is first attached to the transducer surface but to effect polymerization we used two different approaches (dip-coating of a prepolymerization solution on the transducer surface functionalized with the initiator or immersing it in the solution of monomers and testosterone) followed by exposure to an energy source to effect polymerization. Then, analytical performances (linear range, detection limit, selectivity and reproducibility) of both creatinine and testosterone sensors were determined and compared
876

Evaluation of photocatalytic activity of porous films by in-situ environmental ellipsometric analysis / Evolution de l'activité photocatalytique de films minces poreux par analyse ellipsométrique environnementale in-situ

Li, Ronghua 02 March 2016 (has links)
Les matériaux à base de TiO2 ont déjà été très étudiés. En particulier, les films minces mésoporeux cristallins de TiO2 montrent une activité photo-catalytique élevée due à leur surface spécifique incomparable. Cependant, l'étude et l'optimisation de la photocatalyse dans un tel milieu poreux n'est pas si simple car le processus catalytique dépend de plusieurs paramètres environnementaux et structuraux. Les activités de recherche se sont essentiellement focalisées sur (i) la conception de couches mésoporeuses à base de TiO2 avec une composition et une nanostructure variée et (ii) leur mise en œuvre comme plateforme pour une étude fondamentale par ellipsométrie concernant le processus photocatalytique. Des films mésoporeux ont été produits en couplant la chimie sol-gel, et des procédés de dépôt. Parmi des outils de caractérisation analytiques, 2D-GISAXS, ellipsométrie, SEM-FEG, HR-TEM et WAXS sont notamment les techniques qui ont été utilisées pour obtenir des informations. Premièrement, un film mésoporeux de TiO2 a été analysé par ellipsométrie in-situ pour des investigations fondamentales sur les cinétiques de son processus photocatalytique dans l'air en fonction de la composition environnementale et du polluant organique. La grosse quantité d'information obtenue a d'ailleurs permis la proposition de mécanismes de photo-dégradation dans les conditions étudiées. Dans la seconde partie, des films minces mésoporeux mixtes TiO2/SiO2 avec des propriétés optiques ajustables ont été préparées. Une étude structurale a été conduite sur le réseau et la composition des films poreux. L'ellipsométrie a été également mis en œuvre pour étudier leur le activité photocatalytique. / TiO2-based materials have been extensively studied as potential material to be used in photocatalysis. In particular crystalline mesoporous thin films exhibit increased photocatalytic activities due to their exceptionally high surface area. However the study and the optimization of the photocatalysis in such porous media is not easy to be done due to the fact that the catalytic process is highly dependent from several environmental and structural parameters. The research activities of this thesis were essentially focused on (i) the fabrication of mesoporous TiO2-based photoactive thin films with tunable composition and nanostructure and (ii) their utilization as platform for fundamental study of the photocatalytic process by ellipsometry. The mesoporous films with tunable nanostructure will be fabricated by coupling sol-gel chemistry and highly controlled liquid deposition techniques. Among modern analytical tools, 2D-GISAXS, ellipsometry and ellipso-porosimetry, SEM-FEG, HR-TEM and WAXS, were used to obtain a large set of relevant information. In the first part, a model TiO2 mesoporous film was analysed by ellipsometry for fundamental investigations of the photocatalytic process kinetics in air as function of the environmental and the organic pollutant. The information obtain by ellipsometry has allowed the proposition of photodegradation mechanisms in the studied conditions. In the second part, composite mesoporous TiO2/SiO2 films with tunable optical properties were fabricated by sol-gel chemistry. A structural study on the films porous network and composition was conducted. In-situ ellispometry was also used to study the photocatalytic activity.
877

Determination of the stress field in polycrystalline materials by Laue microdiffraction / Détermination du champ de contraintes dans les matériaux cristallins par microdiffraction Laue

Zhang, Fengguo 07 July 2015 (has links)
La microdiffraction Laue permet l'estimation des déformations élastiques à l'échelle du micron. La procédure d'analyse standard, bien établie, utilisée pour extraire les déformations élastiques des images de Laue est limitée par deux sources d'erreurs : la détermination de la positions des taches de Laue sur le détecteur, et la sensibilité aux paramètres de calibration du montage. Pour améliorer la procédure, nous avons développé une procédure appelée Laue-DIC qui utilise la très bonne résolution de la technique de corrélation d'images numériques (DIC). Cette méthode utilise, pour la détermination de l'incrément de déformation élastique et de rotation, le déplacement des pics entre deux configurations mécaniques, estimé par DIC, au lieu de leur position. Nous montrons que cette méthode donne un profil de contrainte en meilleur accord avec les solutions analytiques et numériques, pour des échantillons monocristallins déformés en flexion 4-points. Nous proposons également une méthode Laue-DIC améliorée, dans laquelle les paramètres de calibration sont estimés à chaque point de mesure, simultanément à la déformation élastique.En parallèle à la formulation de la méthode Laue-DIC (améliorée), nos efforts ont porté sur l'estimation de l'incertitude obtenue sur les déformations élastiques. Nous avons développé un modèle de bruit pour les images de Laue mesurées en rayonnement synchrotron, qui a été validé sur des séries de données, et qui nous a permis d'estimer les erreurs statistiques de la DIC, à partir d'images de Laue synthétiques. Ces erreurs ont ensuite été propagées dans la méthode Laue-DIC afin d'estimer les incertitudes sur les déformations élastiques, que l'on trouve en bon accord avec la fluctuation des contraintes locales estimées. / Laue microdiffraction is a powerful technique to characterize the intragranular elastic strain field at the scale of micrometer. Although a standard procedure extracting elastic strain and crystal orientation from Laue image has been well-established, it can suffer from two sources of uncertainties: the determination of peaks' positions and the sensitivity to calibration parameters. In light of the high accuracy of digital image correlation (DIC), we developed the so-called Laue-DIC method which used the peaks' displacements measured by DIC instead of peaks' positions to determine the elastic strain increment and rotation between two mechanical configurations. This method has been proved more efficient than the standard procedure in terms of stress profiles of bended beam. We also developed the enhanced version of Laue-DIC. By using the term “enhanced”, we mean that we attempt to obtain both lattice matrices and calibration parameters of two configurations rather than solely the elastic strain increment and rotation from peaks' displacements.Aside from the formulation of Laue-DIC, we also developed a procedure of statistically estimating the errors of elastic strain/stress resulted from DIC errors and calibration accuracy. We have first validated a classical noise model, Poissonian-Gaussian model, from diffraction images acquired at synchrotron radiation facility. With the noise model, we could statistically estimate the DIC errors by synthesizing artificial spots. The estimated DIC errors were further transmitted into the errors of Laue-DIC through statistical tests.
878

Les énoncés nominaux en français au regard du japonais / Nominal Utterances in Written French compared to Japanese / フランス語書き言葉における名詞発話文 ー日本語の理論に照らしてー

Kurihara, Yui 16 June 2017 (has links)
Le travail présenté dans cette thèse traite les séquences nominales en français écrit employées seules en dehors des énoncés verbaux, munies cependant d’une référence au monde. Dans le but d’apporter un nouvel éclairage sur de telles séquences nominales, traitées traditionnellement dans le cadre de la phrase, i.e. d’une relation prédicative entre deux termes, nous les appelons énoncés nominaux et adoptons la perspective de la grammaire japonaise qui n’est que partiellement influencée par la logique occidentale. Dans la théorie des Jutsu-tai/ Kan-tai (énoncés verbaux/ énoncés nominaux) de YAMADA Yoshio 山田孝雄 (1936), l’un des précurseurs de la grammaire japonaise, à laquelle nous recourons particulièrement, l’énonciation nominale s’explique, et ainsi s’oppose à l’énonciation verbale, par son mode d’embrayage particulier ; alors que la référence au monde des Jutsu-tai (énoncés verbaux) se définit au plan sémantico-syntaxique par la présence d’un verbe saturé et conjugué, les Kan-tai, les énoncés composés d’une séquence nominale qui n’a en soi aucune prédilection pour une fonction syntaxique spécifique, acquièrent leur énonçabilité en énonciation, par le mode même de l’énonciation. Ce mode, « Yobikake shij-suru yôtai (mode de désigner par appellation) » (YAMADA), que nous traduisons plutôt « désignation in situ », se caractérise par la mise en relation in situ entre l’énonciateur et l’entité désignée par la séquence nominale. Ce qui distingue l’énonciation nominale d’avec l’énonciation verbale qui n’est autre chose qu’une mise en relation prédicative entre deux termes du même niveau sémantico-syntaxique. / The purpose of this study is to investigate the noun phrases in written French outside of the context of verbal utterances, but nevertheless referring to the world. In order to illuminate such nominal phrases from a new angle, which have traditionally only been considered with respect to the sentence, i.e. to the predication between a subject and a predicate, this study calls them nominal utterances and adopts the perspective of Japanese grammar, which has not been influenced by the logic of Occidental grammar. In the definitions of Jutsu-tai and Kan-tai put forth by YAMADA Yoshio 山田孝雄 (1936), — verbal utterance and nominal utterance, respectively — a foundational text on Japanese grammar to which this study engages with, YAMADA defines nominal enunciations in contrast to verbal enunciations as a specific mode of anchoring. Whereas the reference to the world of Jutsu-tai (verbal utterances) is defined at the semantic-syntactic level by the presence of a conjugated verb with its arguments, (Kan-tai), utterances consisting of a noun phrase, which are not intended to assume a specific syntactic role per se, acquire the possibility of functioning as an utterance by the mode of enunciation itself. This mode, called « Yobikake shij-suru yôtai (mode of designation by naming) » (YAMADA), which this study translates as “designation in situ,” is characterised by establishing the relationship between the utterer and the referent of the noun phrase. This relationship distinguishes the nominal enunciation from the verbal enunciation by establishing the relationship between two arguments at semantic-syntactic level.
879

Caractérisation des systèmes hydro-climatiques à l'échelle locale dans l'Himalaya népalais / Characterization hydro-climatic systems at the local scale in the Nepalese Himalayas

Eeckman, Judith 30 October 2017 (has links)
La partie centrale de la chaîne himalayenne présente d’importantes hétérogénéités, en particulier en termes de topographie et de climatologie. La caractérisation des processus hydro-climatiques dans cette région est limitée par le manque de descriptif des milieux. La variabilité locale est alors difficilement représentée par les modélisations mises en œuvre à une échelle régionale.L’approche proposée dans ce travail est de caractériser les systèmes hydro-climatiques à l’échelle locale pour réduire les incertitudes liées à l’hétérogénéité du milieu. L’intégration de données localement précises est testée pour la modélisation de bassins versants peu instrumentés et fortement hétérogènes.Deux sous-bassins du bassin de la Dudh Koshi (Népal) sont utilisés comme échantillons représentatifs des milieux de haute et moyenne montagne, hors contribution glaciaire. Le schéma de surface ISBA est appliqué à la simulation des réponses hydrologiques des types de surface décrits à partir d’observations de terrain. Des mesures de propriétés physiques des sols sont intégrées pour préciser la paramétrisation des surfaces dans le modèle. Les données climatiques nécessaires sont interpolées à partir des observations in situ disponibles. Une approche non déterministe est appliquée pour quantifier les incertitudes liées à l’influence de la topographie sur les précipitations, ainsi que leur propagation aux variables simulées. Enfin, les incertitudes liées à la structure des modèles sont évaluées à l’échelle locale à travers la comparaison des paramétrisations et des résultats de simulation obtenus d'une part avec le schéma de surface ISBA, couplé à un module de routage à réservoir et d'autre part avec le modèle hydrologique J2000. / The central part of the Hindukush-Himalaya region presents tremendous heterogeneity, in particular in terms of topography and climatology. The representation of hydro-climatic processes for Himalayan catchments is limited due to a lack of knowledge regarding their hydrological behavior. Local variability is thus difficult to characterize based on modeling studies done at a regional scale. The proposed approach is to characterize hydro-climatic systems at the local scale to reduce uncertainties associated with environmental heterogeneity.The integration of locally reliable data is tested to model sparsely instrumented, highly heterogeneous catchments. Two sub-catchments of the Dudh Koshi River basin (Nepal) are used as representative samples of high and mid-mountain environments, with no glacier contribution. The ISBA surface scheme is applied to simulate hydrological responses of the surfaces that are described based on in-situ observations. Measurements of physical properties of soils are integrated to precise surface parametrization in the model. Necessary climatic data is interpolated based on available in-situ measurements. A non deterministic approach is applied to quantify uncertainties associated with the effect of topography on precipitation and their propagation through the modeling chain. Finally, uncertainties associated with model structure are estimated at the local scale by comparing simulation methods and results obtained on the one hand with the ISBA model, coupled with a reservoir routing module, and on the other hand, with the J2000 hydrological model.
880

Modelling and experimental validation of the hygrothermal performances of earth as a building material / Modélisation et validation expérimentale des performances hygrothermiques de la terre comme matériau de construction

Soudani, Lucile, Caroline, Laurence 09 December 2016 (has links)
La thèse s'inscrit dans un projet de recherche national (ANR Primaterre) qui a pour but d'étudier les performances (mécaniques et thermiques) réelles des matériaux de construction premiers à faible énergie grise que sont la terre crue et la limousinerie.Le travail de thèse se concentre sur les aspects thermiques et hygrothermiques de la terre crue, c'est-à-dire le couplage entre les transferts de masse d'eau (liquide et vapeur) et de chaleur au sein du matériau. Dans une première partie, une analyse des performances thermiques et hydriques d'une habitation comportant des murs en pisé (terre crue compactée) instrumentés a été réalisée. Cette étude a été complétée par la mesure, en laboratoire, des propriétés thermiques et hydriques du matériau. Le lien entre les paramètres matériaux mesurés et les performances (hygro)-thermiques a été appréhendé à la lumière d'un modèle numérique couplé, adapté aux caractéristiques particulières du matériau. Cette étude a mis en évidence que, de par leur aptitude à stocker puis restituer l'énergie solaire, leur capacité de stockage hydrique et la complexité des transports et changements de phases de l'eau se produisant en leur sein, les murs en terre crue présentent de nombreuses particularités qu'il convient de prendre en compte pour une bonne prédiction de leur impact sur les performances d'une habitation. / The Ph.D. is part of a national research project (ANR Primaterre) aiming at promoting real performances (mechanical and thermal) of primary construction materials with low embodied energy such as raw earth.This work focuses on the thermal and hygrothermal behaviour of rammed earth, i.e. coupled transfers of heat and moisture (liquid water and water vapour) within the material. On the one hand, an evaluation of the thermal and hygric performances of a monitored house with rammed earth walls is provided. This study is completed with laboratory measurements of the thermal and hydric properties of the material. A numerical coupled model, suitable for the specific characteristics of the material, provides a better understanding of the link between the characterization parameters measured and its (hygro)thermal performances. Because of their ability to store and release heat from the sun, their capacity to store moisture and the complexity of the transfers occurring in their pores, earthen walls display many distinctive features that are essential to count for in order to provide an accurate prediction of their impact on the global performances of a building.

Page generated in 0.064 seconds