Orientadores: Shirlei Maria Recco Pimentel , Gisele Orlandi Introíni / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-27T14:18:00Z (GMT). No. of bitstreams: 1 Santos_JulioSergiodos_D.pdf: 6299599 bytes, checksum: 7b5ca57cc296e80450e00cfd661976ad (MD5) Previous issue date: 2015 / Resumo: Os anuros da família Leptodactylidae estão alocados em três subfamílias: Leiuperinae, Leptodactylinae e Paratelmatobiinae. Com o auxílio da microscopia eletrônica, foram observados os espermatozoides de 23 espécies de leptodactilídeos buscando-se contribuir com elementos para o entendimento de incertezas filogenéticas. Em Pseudopaludicola, gênero alocado em Leiuperinae, é comparado o espermatozoide de representantes do grupo P. pusilla e de espécies dos quatro clados recuperados na filogenia molecular, os quais correspondem aos grupos cromossômicos 2n=22, 20, 18 e 16. A análise das espécies de Pseudopaludicola mostrou que as cabeças dos espermatozoides são semelhantes e contém a vesícula acrossomal cobrindo o cone subacrossomal. Já as caudas dos espermatozoides de Pseudopaludicola apresentam diferenças marcantes. Nas espécies com número cromossômico 2n=22, Pseudopaludicola sp. 1 (grupo P. pusilla), P. saltica, P. falcipes e P. mineira, as caudas exibem fibras acessórias (justa-axonemal, membrana ondulante e a fibra axial). Essas fibras também são observadas em P. ternetzi e P. ameghini, ambas do clado com 2n=20, mas nas suas caudas a fibra axial é mais desenvolvida. Nos indivíduos do clado com número cromossômico 2n=18, P. canga, P. facureae, P. giarettai, P. atragula e Pseudopaludicola sp. 2 e com 2n=16, P. mystacalis, a cauda apresenta a membrana ondulante espessa, caracterizando um bastão para-axonemal, o qual é mais curto do que a membrana ondulante da cauda dos Pseudopaludicola com número cromossômico 2n=22 e 20. As diferenças morfológicas ultraestruturais observadas nas caudas dos espermatozoides indicam que esses caracteres podem ser filogeneticamente informativos, quando mapeados na filogenia molecular, pois os perfis ultraestruturais da cauda coincidem parcialmente com a formação dos quatro clados filogenéticos e possibilitam levantar a hipótese de uma progressiva simplificação do espermatozoide durante a evolução do gênero Pseudopaludicola. A análise comparativa de espécies entre os gêneros de leiuperíneos mostra que as caudas dos espermatozoides de Physalaemus (P. albifrons, P. centralis, P. cicada e P. cuvieri), também exibem fibras acessórias, como a fibra justa-axonemal e a membrana ondulante, contudo, a membrana ondulante nesse gênero é mais longa que aquela encontrada em Pseudopaludicola. Além disso, as caudas dos espermatozoides de Physalaemus não mostram fibra axial. Do gênero Engystomops, grupo irmão de Physalaemus, foram analisadas E. petersi, E. freibergi e E. puyango, cujas caudas apresentam fibra justa-axonemal, membrana ondulante e fibra axial. Esses gêneros diferem ainda pela membrana ondulante mais curta em Engystomops, corroborando a revalidação do gênero Engystomops. A cauda de Engystomops puyango difere de E. petersi e E. freibergi, clado Duovox, e é igual a E. pustulosus, do clado Edentulus, indicando a necessidade de ampliar os estudos desse gênero. A espécie Pleurodema diplolister, do gênero próximo a Physalaemus e Engystomops, apresenta na cauda do espermatozoide a fibra justa-axonemal e a membrana ondulante, as quais são semelhantes àquelas observadas nas espécies de Physalaemus, entretanto, a membrana ondulante de P. diplolister é menor que a observada em Physalaemus. A comparação dos espermatozoides de representantes das outras subfamílias de Leptodactylidae mostrou que Paratelmatobiinae, representada por P. poecilogaster, apresenta estruturas iguais àquelas observadas nos Pseudopaludicola do clado com número cromossômico 2n=22. Por outro lado, a espécie analisada, Leptodactylus natalensis, Leptodactylinae, apresenta fibra axial bem desenvolvida, diferente daquela exibida nos espermatozoides de Engystomops, Pseudopaludicola e P. poecilogaster. A outra espécie de Leptoctylinae, Adenomera marmorata, a qual era alocada em Leptodactylus, apresenta apenas o axonema na cauda do espermatozoide. Essa diferença ultraestrutural das caudas de A. marmorata e L. natalensis, corrobora com a re-alocação de A. marmorata como espécie válida e diferente de Leptodactylus. A descrição ultraestrutural dos gametas masculinos leptodactilídeos mostra caracteres filogenéticos informativos, principalmente aqueles das caudas dessas células, que podem ser usados para o entendimento dos relacionamentos intragenérico e intergenérico. / Abstract: The anurans of the family Leptodactylidae are distributed in three subfamilies ¿Leiuperinae, Leptodactylinae and Paratelmatobiinae. The spermatozoa of 23 leptodactylid species were analyzed under an electron microscope in order to provide evidence for the better understanding of a number of phylogenetic uncertainties. In the case of the leiuperine genus Pseudopaludicola, the sperm of the representative of the P. pusilla group and those of four clades identified in the molecular phylogeny, which correspond to well-defined chromosomal groups with 2n=22, 20, 18, and 16, were compared. The analysis of the different Pseudopaludicola species found spermatozoa with heads of similar shape, which contain an acrosomal vesicle covering the subacrosomal cone. However, the tails present marked differences. In the species with 2n=22, that is, Pseudopaludicola sp. 1 (P. pusilla group), P. saltica, P. falcipes and P. mineira the tails present accessory fibers (juxtaxonemal fiber, undulating membrane and axial fiber). Fibers of this type are also observed in P. ternetzi and P. ameghini (representatives of the 2n=20 clade), although the axial fiber is more developed. In the specimens of the 2n = 18 clade (P. canga, P. facureae, P. giarettai, P. atragula and Pseudopaludicola sp. 2) and the 2n=16 clade (P. mystacalis), the tail has a thick undulating membrane, characterized by a paraxonemal rod, which is shorter than the undulating membrane of the tail of Pseudopaludicola (2n=22 and 20). The ultrastructural morphological differences observed in the tails of the spermatozoa indicates that these traits are phylogenetically informative, given their partial correspondence to the four clades identified in the molecular studies, and provide evidence of a progressive simplification of the spermatozoa during the evolution of the genus Pseudopaludicola. The comparative analysis of the leiuperine genera indicates that in Physalaemus (P. albifrons, P. centralis, P. cicada and P. cuvieri), the tail of the spermatozoon also shows accessory fibers, such as the juxtaxonemal and the undulating membrane, although in this genus, the membrane is longer than that observed in Pseudopaludicola. In addition, there is no axial fiber on the tail of the spermatozoon in Physalaemus. In the case of Engystomops, sister group of Physalaemus, the species E. petersi, E. freibergi, and E. puyango the sperm tail presents all three types of fiber (juxtaxonemal, undulating membrane and axial fiber). The tail of these two genera also differ each other for the shorter undulating membrane in Engystomops, corroborating the revalidation of the genus Engystomops. Additionaly, the tail of E.puyango differs from E. petersi and E. freibergi, Duovox clade, and it is similar to E. pustulosus, Edentulus clade, indicating the need of more studies in this genus. In Pleurodema diplolister, representing the genus closest to Physalaemus and Engystomops, the sperm tail has a juxtaxonemal fiber and undulating membrane, which are similar to those found in Physalaemus, although the membrane observed in Pleurodema diplolister is shorter than that observed in Physalaemus. Comparisons with other leptodactylid subfamilies indicated that the Paratelmatobiinae, represented by P. poecilogaster, has the same structures as those observed in the 2n = 22 clade of Pseudopaludicola. On the other hand, the leptodactyline species analyzed, Leptodactylus natalensis, has a well-developed axial fiber, distinct from that found in the sperm of Engystomops, Pseudopaludicola and P. poecilogaster. However, in the other leptodactyline species analyzed, Adenomera marmorata, previously allocated to Leptodactylus, the sperm tail has only an axoneme. This ultrastructural difference in the tails of A. marmorata and L. natalensis supports the status of A. marmorata as a valid taxon distinct from Leptodactylus. Overall, then, the ultrastructural description of the male gametes of a selection of leptodactylid species provided informative phylogenetic characters, especially with regard to the morphology of the sperm tails, which can be used for understanding of the intrageneric and intergeneric relationships / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

Com o objetivo de estudar os possíveis efeitos da administração sistêmica de glutamina ou da associação de hidrocortisona, dimetilsulfóxido, ácido ascórbico e pentoxifilina nas lesões de isquemia e reperfusão no cólon maior, foram utilizados dezoito equinos. Sob anestesia geral e controle da oximetria de pulso e pressão arterial, os equinos foram submetidos a laparotomia e em um segmento do cólon maior foi induzida isquemia venosa total. Após uma hora de isquemia, seis equinos do Grupo G receberam glutamina (25mg/Kg IV), seis equinos do Grupo A receberam uma associação de hidrocortisona (4mg/Kg IV), dimetilsulfóxido (20mg/Kg IV), ácido ascórbico (50mg/Kg IV), e pentoxifilina (10mg/Kg IV) e os seis equinos do Grupo C receberam apenas solução de Ringer com lactato e constituíram o Grupo controle. Após duas horas de isquemia o fluxo sanguíneo local foi restabelecido. Decorridas duas horas de reperfusão foi realizada a laparorrafia e permitiu-se a recuperação anestésica. Seis horas após o início da reperfusão os equinos do Grupo G receberam novamente 25mg/Kg de glutamina, enquanto os equinos dos Grupos A e C receberam apenas solução de Ringer com lactato. Doze horas após o início da reperfusão os equinos foram eutanasiados. Foram colhidas amostras de cólon antes da indução da isquemia, após duas horas de isquemia e após duas e doze horas de reperfusão, que foram submetidas a avaliação histomorfológica, ultra-estrutural e determinação da atividade de mieloperoxidase. Os resultados para todas as variáveis estudadas foram semelhantes entre os grupos, permitindo concluir que os tratamentos, nas condições em que foram empregados neste estudo, não foram eficazes em atenuar as alterações decorrentes de isquemia e reperfusão no cólon maior de equinos. / This study was designed to evaluate the effects of intravenous administration of glutamine or the association of hydrocortisone, dimethyl sulphoxide, ascorbic acid and pentoxifylline on ischemia reperfusion lesions of the large colon. A segment of the large colon was isolated in 18 horses under inhalant general anesthesia and total venous ischemia was induced. One hour after the onset of ischemia, glutamine (25mg/Kg IV) was administered to six horses (G group), an association of hydrocortisone (4mg/Kg IV), dimethyl sulphoxide (20mg/Kg IV), ascorbic acid (50mg/Kg IV) and pentoxifylline (10mg/Kg IV) was administered to six horses, and the others received only isotonic fluids and remained as the control group (C). After 2 hours of ischemia and 2 hours of reperfusion the abdomen was closed and the horses were allowed to recover from anesthesia. After 6 hours of reperfusion, horses of group G received another dose of glutamine (25mg/Kg IV) whereas groups A and C received only isotonic fluids. Horses were euthanatized 12 hours after reperfusion. Biopsies were taken from the large colon before and after 2 hours of ischemia and after 2 and 12 hours of reperfusion. Alterations were evaluated under light and scanning electronic microscopy and scored. Additionally, mieloperoxidase (MPO) activity was measured. Results showed that scores for mucosal lesion, edema, hemorrhage, neutrophil infiltration and MPO activity during IR were similar between groups G, A and C. It was concluded that treatments were not effective in attenuating effects of ischemia and reperfusion in the equine large colon.

Com o objetivo de estudar os possíveis efeitos da administração sistêmica de glutamina ou da associação de hidrocortisona, dimetilsulfóxido, ácido ascórbico e pentoxifilina nas lesões de isquemia e reperfusão no cólon maior, foram utilizados dezoito equinos. Sob anestesia geral e controle da oximetria de pulso e pressão arterial, os equinos foram submetidos a laparotomia e em um segmento do cólon maior foi induzida isquemia venosa total. Após uma hora de isquemia, seis equinos do Grupo G receberam glutamina (25mg/Kg IV), seis equinos do Grupo A receberam uma associação de hidrocortisona (4mg/Kg IV), dimetilsulfóxido (20mg/Kg IV), ácido ascórbico (50mg/Kg IV), e pentoxifilina (10mg/Kg IV) e os seis equinos do Grupo C receberam apenas solução de Ringer com lactato e constituíram o Grupo controle. Após duas horas de isquemia o fluxo sanguíneo local foi restabelecido. Decorridas duas horas de reperfusão foi realizada a laparorrafia e permitiu-se a recuperação anestésica. Seis horas após o início da reperfusão os equinos do Grupo G receberam novamente 25mg/Kg de glutamina, enquanto os equinos dos Grupos A e C receberam apenas solução de Ringer com lactato. Doze horas após o início da reperfusão os equinos foram eutanasiados. Foram colhidas amostras de cólon antes da indução da isquemia, após duas horas de isquemia e após duas e doze horas de reperfusão, que foram submetidas a avaliação histomorfológica, ultra-estrutural e determinação da atividade de mieloperoxidase. Os resultados para todas as variáveis estudadas foram semelhantes entre os grupos, permitindo concluir que os tratamentos, nas condições em que foram empregados neste estudo, não foram eficazes em atenuar as alterações decorrentes de isquemia e reperfusão no cólon maior de equinos. / This study was designed to evaluate the effects of intravenous administration of glutamine or the association of hydrocortisone, dimethyl sulphoxide, ascorbic acid and pentoxifylline on ischemia reperfusion lesions of the large colon. A segment of the large colon was isolated in 18 horses under inhalant general anesthesia and total venous ischemia was induced. One hour after the onset of ischemia, glutamine (25mg/Kg IV) was administered to six horses (G group), an association of hydrocortisone (4mg/Kg IV), dimethyl sulphoxide (20mg/Kg IV), ascorbic acid (50mg/Kg IV) and pentoxifylline (10mg/Kg IV) was administered to six horses, and the others received only isotonic fluids and remained as the control group (C). After 2 hours of ischemia and 2 hours of reperfusion the abdomen was closed and the horses were allowed to recover from anesthesia. After 6 hours of reperfusion, horses of group G received another dose of glutamine (25mg/Kg IV) whereas groups A and C received only isotonic fluids. Horses were euthanatized 12 hours after reperfusion. Biopsies were taken from the large colon before and after 2 hours of ischemia and after 2 and 12 hours of reperfusion. Alterations were evaluated under light and scanning electronic microscopy and scored. Additionally, mieloperoxidase (MPO) activity was measured. Results showed that scores for mucosal lesion, edema, hemorrhage, neutrophil infiltration and MPO activity during IR were similar between groups G, A and C. It was concluded that treatments were not effective in attenuating effects of ischemia and reperfusion in the equine large colon.

Orientador: Helena Maria Andre Bolini Cardello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T19:15:52Z (GMT). No. of bitstreams: 1 Silva_Karla_M.pdf: 2005223 bytes, checksum: cdd75d59efe54c8d3d07fe38f86b7b39 (MD5) Previous issue date: 2004 / Resumo: O soro de leite bovino é um subproduto da manufatura de queijo ou caseína caracterizado por sua funcionalidade e valor biológico. O soro ácido, obtido da coagulação ácida do leite, apesar do seu valor funcional ainda é considerado um rejeito industrial. Neste contexto, foi proposta a adição de produto do soro ácido de leite (SAP), em cinco diferentes níveis de substituição do leite em pó, na formulação de sorvete. A avaliação do efeito provocado, pela introdução do SAP no sorvete, foi feita por teste sensorial. Considerando ainda os fabricantes de sorvete que, reconhecendo a importância funcional e nutricional dos produtos de soro de leite, gostariam de aumentar os níveis de substituição por estes produtos em suas formulações, efetuou-se aplicação de leite em pó desnatado e diferentes substituintes deste (SAP, soro desmineralizado e concentrado protéico de soro 35%), comparando-se os resultados. A primeira etapa do trabalho identificou uma boa aceitação dos provadores para o produto contendo 30% de SAP, sendo este nível selecionado para continuidade do trabalho. Na segunda etapa as misturas foram caracterizadas (proteína, gordura, minerais, açúcar, sólidos totais, pH, acidez titulável, viscosidade, temperatura de congelamento e frações protéicas) e os produtos aerados e congelados submetidos a avaliações físicas (potencial de aeração, firmeza e resistência ao derretimento), aspectos ultra-estruturais e testes sensoriais. Os resultados demonstraram que a introdução do SAP aumentou a viscosidade da mistura, manteve o potencial de aeração, estabilizou a firmeza e melhorou a estrutura microscópica do sorvete comparativamente com a formulação padrão (sem substituição do leite). Houve boa aceitação dos provadores para as formulações com substituição do leite desnatado por 30% de SAP, 100% de desmineralizado e 100% de concentrado protéico de soro / Abstract: Whey protein is a by product of cheese or casein production, which is characterized by a high functionality and biological value. Acid whey protein is obtained by acid coagulation of milk, has been viewed as dairy wastes so represent a critical environmental pollution. In this context, we proposed the acid whey addition in ice cream formulations, as a dry skim milk total or parcial substitute, ascertaining by sensory evaluation the panelists acceptance for five different substitutions levels. Ice cream manufacturers interesting in increasing the percentual of this product in ice cream formulations showed the importance of the comparative application of dry skim milk and others different replacers (acid whey product, demineralized whey and whey protein concentrate) in ice cream formulations. At the first stage of this work a good panellists acceptance for 30% acid whey product content product was obtained then this level was selected to the followed experiments. In the second level mixtures were characterized (protein, fat, minerals, sugar, total solids, pH, titratable acidity, viscosity, freezing temperature and proteins fractions) and whippened and freezing products were submitted to physical evaluations (whipping potential, firmness and melting resistance), structural electron microscopy aspects and sensory evaluations. Results showed that acid whey addition in ice cream formulations increased the viscosity of mix, maintained the whipping ability, stabilized the firmness and improved the microscopic structure, as the standard product comparison (formulation without milk substitutions). There was good sensory panel acceptance for all milk substituted formulations (30% acid whey product, 100% demineralized whey and 100% whey protein concentrate) / Mestrado / Mestre em Alimentos e Nutrição

Les prothèses diaphragmatiques en ePTFE utilisées dans la hernie diaphragmatique congénitale à large défect ont une faible étirabilité, ce qui entrainera des récidives herniaires au cours de la croissance de l’enfant. En effet, l’analyse en imagerie montre que la surface du diaphragme grandit de 4-5 fois jusqu’à l’adolescence. De plus, les mesures de rigidité des surfaces de prothèses explantés, montrent l’influence des contraintes mécaniques appliquées sur la structure des matrices extracellulaires néoformées. Afin de favoriser l’intégration tissulaire du ePTFE, nous avons testé un moyen de fonctionnaliser le ePTFE avec la polydopamine sur une seule face. Le revêtement nanoscopique favorise la colonisation cellulaire. Enfin, ce travail de thèse présente une méthode originale de réalisation d’une nouvelle membrane bicouche avec des propriétés mécaniques conformes aux exigences chirurgicales. Ce biomatériau innovant et prometteur fait actuellement l’objet d’une Déclaration d’invention. / Electron microscopy assessments of ePTFE prosthesis explants for diaphragmatic congenital hernia repair strongly suggest that the tissue responses are directly related to the surface microstructure of the biomaterial. AFM measurements (Young moduli) emphasize the influence of the mechanical stress applied to the implant on the mechanical properties of the newly formed extracellular matrices. In order to guide the host responses, we undertook to functionalize with polydopamine the ePTFE biomaterial. Electron microscopy investigations reveal the interest of that surface treatment regarding cell colonization of implant. To optimize that approach, we developed an original method aimed to coat only one face of the biomaterial. After determination of the growth rate of the diaphragm from birth to adolescence, we explored the possibility to design a new double-faced mesh able to follow body growth. From this point of view, the initial prototypes are promising and under patent application.

La connaissance de la morphologie des faisceaux de fibres blanches, qui connectent des régions cérébrales distantes, est indispensable à la compréhension du fonctionnement cérébral. La tractographie par IRM de diffusion reconstruit indirectement cette anatomie à partir d'algorithmes mathématiques complexes. Après une revue des méthodes proposées pour la validation de la tractographie, nous proposons une méthode originale basée sur la reconstruction 3D de faisceaux disséqués. Notre méthode, FIBRASCAN, utilise des acquisitions itératives de surface en cours de dissection. Les faisceaux étaient segmentés sur chaque surface puis reconstruits par empilement. Un support rigide permettait le recalage entre surfaces puis vers l'IRM. Nous avons démontré la précision de chaque étape de reconstruction, et sa faisabilité sur plusieurs faisceaux. Dans la dernière partie de ce travail, la structure des fibres blanches et les modifications induites par la préparation et la dissection sont explorées en microscopie électronique. Nous avons montré que la dissection préservait la structure des axones et peut ainsi être considérée comme un outil de validation de la tractographie. / The knowledge of the morphology of white matter fiber tracts, which connect distant cerebral areas, is essential to better understand brain functions. Diffusion MR tractography indirectly reconstructs this anatomy using complex mathematical algorithms. After a review of the existing methods for tractography validation, we propose an original method based on 3D reconstruction of dissected tracts. Our method, FIBRASCAN, used iterative surface acquisitions during dissection. The tracts were segmented on each surface and then reconstructed by stacking these surfaces. A rigid support allowed registration between surfaces and then registration to MRI. We demonstrated the accuracy of each reconstructing step, and the feasibility of our method on several tracts. In the last part of this work, the structure of white matter fibers and the changes induced by preparation and dissection were investigated using electron microscopy. We showed that dissection preserves the structure of axons and can thus be considered as a validation tool for tractography.

Les composés intermétalliques à base de terres rares et de métaux de transition présentent des propriétés magnétiques intéressantes pour les applications technologiques (aimants permanents, enregistrement magnétique à haute densité, réfrigération magnétique…).Ce travail est dédié à l'étude des propriétés structurales, magnétiques et magnétocaloriques des composés Pr2Fe17 dérivant de la structure Th2Zn17. Les propriétés magnétiques intrinsèques recherchées pour des propriétés performantes de ces composés sont améliorées sous l'effet de la substitution (fer par aluminium et praséodyme par dysprosium) et/ou l'insertion d'un élément léger (carbone). Les nanomatériaux intermétalliques sont élaborés par broyage à haute énergie suivi de recuit, ce qui pourrait conduire à des phases hors équilibre thermodynamique. L'homogénéité des alliages a été systématiquement analysée par diffraction des rayons X suivi de l'affinement Rietveld et par microscopie électronique en transmission. Les résultats ont montré qu'on peut former la phase désirée monophasée en faisant un broyage suivi d'un recuit de 30 min au lieu d'un recuit de 7 jours pour les composés massifs. Ceci représente un gain de temps non négligeable. D'après les mesures magnétiques effectuées, tous les composés possèdent une transition de phase de second ordre. Leur température de Curie augmente avec le taux d'Al et de Dy alors que la variation d'entropie diminue légèrement. Par ailleurs, l'insertion d'atomes interstitiels tels que le carbone a été réalisée. On remarque une nette amélioration de la température de transition. Il ressort de cette étude que ces composés présentent un grand intérêt dans la recherche de futurs matériaux magnétocaloriques pour la réfrigération magnétique à température ambiante / The intermetallic compounds based on rare earth and transition metals present interesting magnetic properties for technological applications (permanent magnets, high density magnetic recording, magnetic refrigeration ...).This work is dedicated to the study of structural, magnetic and magnetocaloric of Pr2Fe17 compounds Th2Zn17-type structure. The intrinsic magnetic properties of these compounds are improved due to the substitution (iron and aluminum by praseodymium by dysprosium) and / or the insertion of a light element (carbon). Intermetallic nanomaterials are prepared by high energy milling and subsequent annealing, which could lead to non-equilibrium phases. The homogeneity of these alloys was checked by X-ray diffraction and by transmission electron microscopy. The results have showed that single-phase can be obtained by milling and annealed during 30 min instead of 7 days annealing for bulk compounds. This represents a considerable saving of time. From the magnetic measurements, all compounds exhibit a second order phase transition. Their Curie temperature increases with the rate of Al and Dy as the entropy change slightly decreases. Moreover, the insertion of interstitial atoms such as carbon was achieved. We notice a significant improvement of the transition temperature. It appears from this study that these compounds are of great interest in the search for future magnetocaloric materials for magnetic refrigeration at room temperature

A Espectroscopia Raman Intensificada pela Superfície (SERS) é um efeito de intensificação da intensidade Raman de uma molécula adsorvida numa superfície metálica nanoestruturada. Esta característica permite a utilização do SERS na caracterização vibracional de sistemas como junções moleculares (JM) (JM são sistemas constituídos de fios moleculares sintetizados em junções do tipo metal|fiomolecular|metal) e, no entendimento de quais características morfológicas de agregados metálicos mais influenciariam no sinal SERS obtido. Portanto, esta tese apresenta os seguintes objetivos: (a) síntese e caracterização de substratos SERS ativos, nanoesferas (AuNE) e nanobastões (AuNB) de ouro e eletrodo de ouro ativado eletroquimicamente; (b) síntese e caracterização SERS de fios moleculares em JM; (c) estudo do acoplamento plasmônico entre as superfícies metálicas em JM; (d) correlação entre SERS - morfologia de agregados individuais de AuNB. Os fios moleculares estudados foram os da família das oligofeniliminas (OPI) e, no melhor do nosso entendimento, esta foi a primeira vez que fios moleculares desta família foram caracterizados por Raman e SERS. As JM apresentaram um comportamento SERS não esperado. Enquanto para o modo vibracional, v(CS), a intensidade da banda se apresentou constante com o aumento do espaçamento entre as nanoestruturas metálicas (para distâncias de até 5 nm), o modo vibracional, β(CH), teve a intensidade de sua banda aumentada. Este comportamento foi explicado considerando a diferente natureza da interação dos plasmons nas JM, sendo estas interações do tipo, ressonância de plasmon de superfície (LSPR) - dipolo imagem, para ambos os modos. No entanto, para o modo β(CH) existe também uma intensificação extra devido ao aumento da polarizabilidade dos fios moleculares com o aumento do número de unidades. A correlação SERS - morfologia dos agregados de AuNB indicam que, para agregados onde predominam interações ponta a ponta, os espectros SERS apresentavam uma maior intensidade quando comparados com aqueles em que interações lado a lado predominavam. No entanto, este comportamento não foi observado para agregados contendo mais do que cinco nanopartículas onde estes dois tipos de interações ocorrem indicando que deve existir um acoplamento dos plasmons destes dois tipos de interações contribuindo para maiores valores de intensidade SERS. / Surface enhanced Raman Spectroscopy (SERS) is a Raman enhancing effect of molecules adsorbed on nanostructured metal surfaces. This characteristic allows the use of SERS in the vibrational study of Molecular Junction systems (MJ) (MJ is a system formed by Molecular Wires (pi-conjugated molecules) synthesized in metal junctions like metal|molecular-wire|metal). In addition, we can also use SERS to understand the influence of morphological characteristic of gold nanostructures. This thesis aims: (a) synthesis and characterization of gold nanospheres (AuNS), nanorods (AuNR) and gold electrode (electrochemically activated); (b) synthesis and vibrational studies of molecular wires in JM; (c) plasmon coupling studies between flat surface and gold nanorods; (d) correlation SERS - AuNR morphology of individual aggregates. For the best of our knowledge, this was the first time that oligophenilenelimine (OPI) as molecular wire was characterized by Raman and SERS. The MJ showed an unusual behavior such that the v(CS) vibrational mode remained constant in intensity with the increasing of the gap spacing (within 5 nm) while the β(CH) increased with the increase of the gap. This behaviour was related to the different nature of the interaction between plasmons resonances in JM (surface plasmon resonance (LSPR) - dipole image) for the first case and due to chemical contributions by the molecular wires for the second vibrational mode. The results for SERS - morphology AuNR aggregates correlation showed (for small aggregates) that when in the aggregate predominated end-by-end interaction SERS spectra showed a higher intensity when compared to those in which interactions side-by-side predominated. Although, this behavior was not observed for aggregates containing more than five nanoparticles indicating that there is not a preferential interaction between the nanorods for such aggregates and that a mixture of both will be preferable for large SERS intensities.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-08-26Bitstream added on 2014-06-13T19:29:33Z : No. of bitstreams: 1 simoes_rd_me_bauru.pdf: 3082806 bytes, checksum: b44fcfd386ae934a75a9814336462470 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal objetivo deste trabalho de mestrado foi a obtenção e caracterização estrutural de um material com propriedades físico-químicas compatíveis com aquelas requeridas por um biomaterial. Filmes contendo diferentes volumes de látex de borracha natural em uma massa fixa de poli(fluoreto de vinilideno) (PVDF), na forma de pó foram fabricados por compressão/aquecimento de uma mistura de ambos os materiais sem o uso de qualquer solvente. Este é um fator importante considerando o uso destes filmes no futuro próximo como biomateriais em diferentes aplicações (indução do crescimento do tecido ósseo, por exemplo), uma vez que os solventes convencionais usados para dissolver o PVDF têm se mostrado tóxicos ao organismo humano. Os filmes foram submetidos a um tratamento via descarga corona de forma que amostras com e sem tal tratamento foram caracterizadas através das técnicas de espectroscopia vibracional via espalhamento Raman e absorção no infravermelho (FTIR), análise térmica via termogravimetria (TG), calorimetria exploratória diferencial (DSC) e análise dinâmico-mecânica (DMA) e microscopias ótica e eletrônica (MEV). As medidas termomecânicas mostraram que os filmes obtidos possuem características mecânicas similares àquelas encontradas no osso humano e boa estabilidade térmica considerando-se a aplicação desejada. As medidas via espectroscopia vibracional indicaram que o PVDF e o látex não interagem quimicamente, compondo uma blenda polimérica. Além disto, os resultados obtidos via micro-Raman mostraram que o aumento da quantidade de látex na blenda permite uma melhor dispersão deste látex na matriz de PVDF quando da produção dos filmes... / The main goal of this work was to obtain and characterize structurally a material with physical-chemical properties compatible with those required for a biomaterial. Films containing different volumes of latex of natural rubber in a fixed mass of poly (vinylidene fluoride) (PVDF) powder were fabricated by compressing/annealing a mixture of both materials without using any solvent. This is an important issue having in mind to use these films in the future as biomaterials in different applications (growing of the bone tissue, for instance) once the solvents used to dissolve the PVDF are toxic to human being. The films were submitted to a corona discharge treatment in a way that samples with and without such treatment were characterized using micro-Raman scattering and Fourier transform infrared absorption (FTIR) spectroscopies, thermo-mechanical techniques using thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamical-mechanical analysis (DMA) and optical and scanning electron microscopies (SEM). The thermo-mechanical measurements revealed that the films present mechanical properties close to that found for the human bone and high thermal stability considering the desired applications. The vibrational spectroscopies showed that the latex and PVDF do not interact chemically leading to the formation of a polymeric blend. Besides, the results recorded using the micro-Raman technique revealed that the higher the amount of latex in the blend, the better the miscibility between both materials. In terms of morphology, the blend surface is formed by two domains: one is rougher and contains the latex well dispersed into the PVDF matrix while the other is smoother and contains both materials as well but in a less homogeneous dispersion. However, as the volume of latex is increased from 0.3 to 1.0 mL, the smoother domains become rarer to be found... (Complete abstract, click electronic address below)

Le virus influenza de type A est un virus à ARN simple brin de polarité négative qui se réplique dans le noyau des cellules infectées. Son génome se compose de huit segments d'ARN viral (ARNv). Chaque segment est recouvert de multiples copies de nucléoprotéines virales (NP). Chacune des extrémités strictement conservées 3' et 5' des huit segments d'ARNv interagit avec une ARN-polymérase ARN-dépendante. Le complexe entre l'ARNv, NP et l'ARN-polymérase ARN-dépendante forme une particule appelée ribonucléoprotéine (RNP) constituant l'entité fonctionnelle pour la réplication du génome viral et sa transcription en ARN messagers. Dans le contexte de la RNP, ces deux processus sont assurés par l'ARN-polymérase ARN-dépendante formée de trois protéines (PA, PB1 et PB2). L'ARN-polymérase du virus influenza A fait l'objet de nombreuses études. Son étude structurale se heurte à la difficulté d'obtenir ce complexe hétérotrimérique sous forme soluble et en grande quantité, deux conditions qu'impose la biologie structurale. Ainsi, durant les huit dernières années, les données structurales à l'échelle atomique n'ont été obtenues que sur des domaines isolés de l'ARN-polymérase laissant l'essentiel de la structure de PB1 inconnue. Pour contourner ce problème, une nouvelle stratégie s'appuyant sur le système d'expression en cellules d'insecte infectées par baculovirus a été développée. Cette stratégie a permis la production d'une forme tronquée de l'ARN-polymérase du virus influenza de type A qui a été étudiée d'un point de vue structural et fonctionnel. Plusieurs reconstructions en trois dimensions ont été obtenues par microscopie électronique et une structure cristalline à faible résolution (7,7 Å) a pu être résolue. Les études fonctionnelles se sont axées sur les activités portées par l'hétérotrimère tronqué et un accent particulier a été mis sur l'étude des interactions avec l'ARN. Les informations sur les activités catalytiques obtenues in vitro ont mis en évidence un rôle clef de certains ions métalliques. Afin de connaitre l'environnement en ions métalliques et cibler leur rôle à l'échelle cellulaire, leur distribution dans la cellule infectée par le virus influenza A a été étudiée par microscopie rayons-X. Cet aspect de l'infection étant très peu documenté, cette étude s'inscrit dans une démarche originale et a offert l'opportunité d'intégrer les données biochimiques et biophysiques à l'échelle de la cellule entière. / Influenza A virus is a negative single stranded RNA virus that replicates in the nucleus of infected cells. Its genome contains eight single stranded negative-sense RNA segments (vRNA) covered by the viral nucleoprotein (NP). The highly conserved 3' and 5' ends of the vRNA are bound to the RNA-dependent RNA-polymerase (RdRp) which consists of three subunits, PA, PB1 and PB2. The complex between vRNA, NP and the RdRp forms a particle called ribonucleoprotein (RNP). The RNP acts as an independent molecular machine for transcription and replication in the nucleus. Within the context of the RNP, these two processes are mediated by the RdRp. The influenza A RdRp complex has been remarkably intractable to structural analysis and in the last eight years, crystal structures of independent domains covering roughly half of the heterotrimeric RdRp have been determined. In addition, electron microscopy reconstructions have described the RdRp. Nonetheless, a complete model characterizing the RdRp as a whole is still lacking. To overcome this issue, a new strategy has been developed to obtain the RdRp heterotrimeric complex using the baculovirus infected cells expression system. This method has produced a truncated form of the flu A RdRp which has been studied from a structural and functional point of view. Several three-dimensional reconstructions by electron microscopy have been obtained and a crystal structure at low resolution (7,7 Å) has been solved. Functional studies focused on the activities carried by the truncated RdRp and a particular emphasis was placed on the study of the interactions with RNA. In vitro functional data showed highly metal ion-dependent activities. To know more about the subcellular metal context, metallic ions distribution in influenza A infected cells has been studied by X-ray microscopy giving the opportunity to integrate biochemical and biophysical data in the context of the whole cell.