El presente trabajo tuvo como objetivo estudiar el efecto de la adición de un extremo polipeptídico hidrofóbico a una enzima, en particular una cutinasa, en la producción, recuperación y purificación por Cromatografía de Interacción Hidrofóbica (HIC). Para realizar este estudio, se escogieron 3 combinaciones de los aminoácidos tirosina (Y), triptófano (W) y prolina (P), y se realizaron mutaciones en la enzima, mediante la técnica de “Polymerase Chain Reaction” (PCR). Se obtuvieron satisfactoriamente las mutantes CutinasaWPWP y Cutinasa-YYY, y en el caso de la combinación YPYPYP se obtuvo una secuencia más larga en 32 aminoácidos que la diseñada, denominada YPY*. Como resultado se obtuvo que dichos extremos aumentaron la hidrofobicidad superficial global teórica de la proteína en un 12,4% en el caso de la Cutinasa-YYY, en un 16,6% en el caso de la Cutinasa-WPWP y en el caso de una correcta construcción de la Cutinasa-YPYPYP, se hubiera incrementado en un 14,1%. En el caso de la Cutinasa-YPY* se estima que la hidrofobicidad superficial teórica es mayor a este último valor, aunque no pudo ser calculado, debido a que no fue posible aplicar los supuestos que permitían determinarla. Las cepas recombinantes de E. coli que expresan estas proteínas se crecieron e indujeron bajo condiciones definidas, y se les extrajo desde la región periplasmática de la célula, obteniéndose una gran variabilidad (> 50 % en algunos casos) en los resultados en cuanto a actividad y proteína total presentes en las muestras. En el caso de la cutinasa mutada con la secuencia YYY se observó una disminución drástica de la concentración de proteína, en comparación con la cepa nativa, al igual que escasa actividad cutinasa. Esto tendría relación con la ausencia de prolina en el extremo adicionado, ya que este aminoácido, más que otorgar hidrofobicidad a la secuencia, le otorgaría estabilidad, debido a que permite la total exposición del extremo al medio y evita que interactúe con otras regiones de la proteína. Se descartó esta mutante durante el proceso de purificación, debido a la casi nula recuperación de proteína.

A sinalização celular desencadeada na presença do hormônio andrógeno em células da próstata é dependente da ativação do receptor de andrógeno (AR), que é um fator de transcrição codificado pelo gene NR3C4. O AR quando não ligado ao hormônio andrógeno é encontrado no citoplasma, e a ligação do hormônio ao AR promove seu deslocamento para o núcleo. O AR se liga a motivos de DNA, promovendo a transcrição de determinados genes por meio de um complexo mecanismo de regulação ainda não totalmente conhecido. Neste trabalho exploramos a capacidade dos RNAs longos intergênicos não-codificadores (lincRNAs) se ligarem ao AR e contribuírem para a regulação transcricional de genes. Utilizamos a imunoprecipitação de RNA, seguida de sequenciamento em larga escala (RIP-Seq) para a identificação e quantificação de lincRNAs associados fisicamente ao AR na linhagem celular de próstata LNCaP. Em paralelo utilizamos dados de transcriptoma e de marcas epigenéticas para verificar se a interação física dos lincRNAs com o AR influenciaria a composição da cromatina e a expressão dos genes vizinhos desses ARA-lincRNAs (Androgen Receptor Associated LincRNAs). Como resultado deste estudo descrevemos pela primeira vez centenas de LincRNAs associados fisicamente ao receptor de andrógeno após o tratamento com o hormônio. Observamos que uma parte desses ARA-lincRNAs pode modificar in cis a expressão de genes codificadores de proteínas vizinhos e essa capacidade de regulação é reforçada pela presença de marcas epigenéticas que são características de reguladores in cis. Além disso, mostramos que as regiões da cromatina contendo domínios topologicamente associativos (TADs) que possuem ARA-lincRNAs apresentam fatores de transcrição, marcas epigenéticas e nível de transcrição gênica diferenciadas. Os resultados apresentados neste trabalho estendem a importância dos lincRNAs durante eventos regulatórios complexos e mostra pela primeira a atuação dessas moléculas em sinergia com um fator de transcrição modificando a cromatina e alterando a regulação gênica. / The cell signaling events triggered in the presence of the androgen hormone in prostate cells is dependent on the activation of the androgen receptor (AR), which is a transcription factor encoded by the NR3C4 gene. AR when not bound to the androgen hormone is found in the cytoplasm, and binding of the hormone to AR promotes its displacement to the nucleus. AR binds to DNA motifs, promoting the transcription of certain genes through a complex regulatory mechanism not yet fully undestood. In this work we explore the ability of long non-coding intergenic RNAs (lincRNAs) to bind to AR and contribute to the transcriptional regulation of genes. We used immunoprecipitation of RNA, followed by large-scale sequencing (RIP-Seq) for the identification and quantification of lincRNAs physically associated with AR in the LNCaP prostate cell line. In parallel we used transcriptome data and data on epigenetic marks to verify whether the physical interaction of lincRNAs with AR would influence the chromatin composition and the expression of genes neighboring these ARA-lincRNAs (Androgen Receptor Associated LincRNAs). As a result of this study we described for the first time in the literature hundreds of LincRNAs physically associated with the androgen receptor after treatment with the hormone. We have observed that part of these ARA-lincRNAs can modify in cis the expression of neighboring protein coding genes and this regulatory ability is enhanced by the presence of epigenetic marks that are characteristic of in cis regulators. In addition, we have shown that chromatin regions containing topologically associating domains (TADs) that possess ARA-lincRNAs have different transcription factors, epigenetic marks and gene transcription levels. The results presented in this work extend the importance of the lincRNAs during complex regulatory events and shows for the first time the performance of these molecules in synergy with a transcription factor modifying the chromatin and altering gene regulation.

A tecnologia dos aços microligados para transporte de gás natural e petróleo tem sido pressionada pelo descobrimento das novas jazidas e o aumento da demanda no mundo. As solicitações ambientais e de resistência mecânica são os parâmetros para o desenvolvimento de aços de alta resistência baixa liga para o transporte de gás e petróleo a menor custo e de forma segura. Neste contexto esta pesquisa investiga, em um aço microligado para tubos API 5L X80, o efeito das transformações de fase obtidas por resfriamentos controlados na fratura induzida por hidrogênio Hydrogen Induced Cracking-(HIC) e nas propriedades mecânicas. Os testes de HIC foram realizados no material como recebido, na espessura da chapa submetida a resfriamentos contínuos e em amostras do material tratadas de forma a simular as regiões de grão grosso da zona afetada pelo calor (GGZAC). Segundo o ciclo de resfriamento, os aços microligados têm microestruturas complexas, como é caso do aço microligado em estudo, onde sua microestrutura, estudada em trabalhos anteriores, é formada principalmente por ferrita, bainita, perlita e microconstituinte austenita/martensita (AM). A morfologia, tamanho, quantidade e distribuição dos produtos de transformação na chapa mudam as propriedades do aço. Esses fenômenos são de grande interesse tecnológico em aços microligados para a fabricação de tubos soldados para o transporte de gás e petróleo, tanto quando a solda é realizada em campo como também durante o encurvamento por indução; aqui as propriedades mecânicas do tubo decorrentes do processo de fabricação termomecânico podem ser degradadas pela ação do aquecimento e dos resfriamentos experimentados na zona afetada pelo calor (ZAC), principalmente na região de GGZAC. A simulação dos ciclos térmicos para o estudo da HIC na espessura da chapa foram realizados em CP austenitizados a 900ºC e submetidos a resfriamentos contínuos no dilatômetro de têmpera. Para simular os ciclos térmicos com resfriamentos controlados focados na GGZAC e a seguir obter CP de tamanho adequado para testes de tração e Charpy, foi necessário fazer os tratamentos térmicos a 1300ºC e resfriamentos contínuos em um simulador termomecânico e dilatômetro Gleeble. O maior tamanho da amostra tratada termicamente neste último equipamento permitiu extrair amostras para avaliar as propriedades mecânicas e a HIC do material, pois as diferentes regiões da ZAC em uma solda real são restritas e não permitem este tipo de ensaios em uma região específica da ZAC. Os resultados permitiram identificar a suscetibilidade de cada microestrutura produto da transformação da austenita na espessura da chapa, sendo a região central da chapa a mais sensível ao hidrogênio no aço como recebido e quando tratado a baixas taxas de resfriamento de 0,5°C/s após austenitizado a 900°C. As bandas grosseiras formadas por estruturas de maior dureza que a matriz na região central diminuíram a resistência à HIC. Da mesma forma nos corpos de prova que simulam a região GGZAC, a fratura induzida pelo hidrogênio foi localizada na região central da espessura embora apresente bainita e ferrita acicular. A falha possivelmente se deve aos elementos remanescentes segregados nesta região central e partição de carbono para os sub contornos de grão da bainita e ferrita que cresceram a partir a austenita primária. As inclusões e precipitados, segundo seu tipo, forma e localização na microestrutura, participam ou não da nucleação e propagação da trinca, sendo a posição mais crítica quando localizadas dentro das estruturas bandeadas. Não foi observada a nucleação de trincas na presença de hidrogênio em precipitados de Nb e Ti. / The technology of microalloyed steels for the transportation of natural gas and oil has been pressed by the discovery of new deposits and the increased demand in the world. Environmental requests for safety and ever increasing mechanical strength are the parameters for the development of high strength low alloy steels for transporting gas and oil at lower cost and safely. In this context, this research investigates, in a microalloyed steel pipe API 5L X80, the effect of phase transformations obtained by controlled cooling on the behavior when loaded with hydrogen - Hydrogen Induced Cracking - (HIC) and in the mechanical properties. HIC tests were performed on as-received material, on samples extracted from the thickness of the plate and subjected to continuous cooling and on samples of the material treated to simulate the coarse-grained regions of heat affected zone (CGHAZ). According to the cooling cycle, the microalloyed steels have complex microstructures: in the steel under evaluation its microstructure, studied in a previous work, consists mainly of ferrite, bainite, pearlite and austenite/martensite constituent (AM). The morphology, size, quantity and distribution of the products of transformation change the properties of plate steel. These phenomena are of great technological interest in microalloyed steels for the fabrication of welded tubes for the transport of gas and oil, when the welding is performed in the field as well as during hot bending; here the mechanical properties of the tube from the process of thermomechanical fabrication can be degraded by the action of heating and cooling experienced in the heat affected zone (HAZ), mainly in the region of CGHAZ. Simulations of thermal cycles for the study of HIC on sheet thickness were performed in coupons subjected to austenitization at 900ºC followed by continuous cooling in the dilatometer. To simulate the thermal cycles with controlled cooling, focused in the CGHAZ, and getting suitable sample sizes for tensile testing and Charpy, it was necessary to austenitize at 1300ºC followed by continuous cooling using the thermal and thermomechanical simulator in a Gleeble dilatometer. Samples heat treated in this equipment were suitable to evaluate the mechanical properties and the HIC of the material for different regions of HAZ, while a real weld would not have enough material to allow this type of testing on a specific region of HAZ. The results showed the susceptibility of each microstructure product of austenite transformation and of the position on the plate thickness. The central region of the plate was more sensitive to hydrogen in the steel as-received and when treated at low cooling rates of 0.5°C/s after austenitization at 900°C. The bands formed by coarse structures of greater hardness than the matrix in the central region decreased the resistance to HIC. Likewise in coupons that simulate the CGHAZ region, the fracture induced by hydrogen was located in the central thickness line, even when the microstructure were bainite and acicular ferrite. Failure there was possibly due to remnants of segregated elements in this central region and carbon partition to the subboundaries of the bainite and ferrite grain that grew from the primary austenite. Inclusions and precipitates, according to their type, shape and location in the microstructure, participating or not in the nucleation and propagation of the crack, were more critical when located within the banded structures; crack nucleation in the presence of hydrogen was not observed at Nb and Ti precipitates.

A tecnologia dos aços microligados para transporte de gás natural e petróleo tem sido pressionada pelo descobrimento das novas jazidas e o aumento da demanda no mundo. As solicitações ambientais e de resistência mecânica são os parâmetros para o desenvolvimento de aços de alta resistência baixa liga para o transporte de gás e petróleo a menor custo e de forma segura. Neste contexto esta pesquisa investiga, em um aço microligado para tubos API 5L X80, o efeito das transformações de fase obtidas por resfriamentos controlados na fratura induzida por hidrogênio Hydrogen Induced Cracking-(HIC) e nas propriedades mecânicas. Os testes de HIC foram realizados no material como recebido, na espessura da chapa submetida a resfriamentos contínuos e em amostras do material tratadas de forma a simular as regiões de grão grosso da zona afetada pelo calor (GGZAC). Segundo o ciclo de resfriamento, os aços microligados têm microestruturas complexas, como é caso do aço microligado em estudo, onde sua microestrutura, estudada em trabalhos anteriores, é formada principalmente por ferrita, bainita, perlita e microconstituinte austenita/martensita (AM). A morfologia, tamanho, quantidade e distribuição dos produtos de transformação na chapa mudam as propriedades do aço. Esses fenômenos são de grande interesse tecnológico em aços microligados para a fabricação de tubos soldados para o transporte de gás e petróleo, tanto quando a solda é realizada em campo como também durante o encurvamento por indução; aqui as propriedades mecânicas do tubo decorrentes do processo de fabricação termomecânico podem ser degradadas pela ação do aquecimento e dos resfriamentos experimentados na zona afetada pelo calor (ZAC), principalmente na região de GGZAC. A simulação dos ciclos térmicos para o estudo da HIC na espessura da chapa foram realizados em CP austenitizados a 900ºC e submetidos a resfriamentos contínuos no dilatômetro de têmpera. Para simular os ciclos térmicos com resfriamentos controlados focados na GGZAC e a seguir obter CP de tamanho adequado para testes de tração e Charpy, foi necessário fazer os tratamentos térmicos a 1300ºC e resfriamentos contínuos em um simulador termomecânico e dilatômetro Gleeble. O maior tamanho da amostra tratada termicamente neste último equipamento permitiu extrair amostras para avaliar as propriedades mecânicas e a HIC do material, pois as diferentes regiões da ZAC em uma solda real são restritas e não permitem este tipo de ensaios em uma região específica da ZAC. Os resultados permitiram identificar a suscetibilidade de cada microestrutura produto da transformação da austenita na espessura da chapa, sendo a região central da chapa a mais sensível ao hidrogênio no aço como recebido e quando tratado a baixas taxas de resfriamento de 0,5°C/s após austenitizado a 900°C. As bandas grosseiras formadas por estruturas de maior dureza que a matriz na região central diminuíram a resistência à HIC. Da mesma forma nos corpos de prova que simulam a região GGZAC, a fratura induzida pelo hidrogênio foi localizada na região central da espessura embora apresente bainita e ferrita acicular. A falha possivelmente se deve aos elementos remanescentes segregados nesta região central e partição de carbono para os sub contornos de grão da bainita e ferrita que cresceram a partir a austenita primária. As inclusões e precipitados, segundo seu tipo, forma e localização na microestrutura, participam ou não da nucleação e propagação da trinca, sendo a posição mais crítica quando localizadas dentro das estruturas bandeadas. Não foi observada a nucleação de trincas na presença de hidrogênio em precipitados de Nb e Ti. / The technology of microalloyed steels for the transportation of natural gas and oil has been pressed by the discovery of new deposits and the increased demand in the world. Environmental requests for safety and ever increasing mechanical strength are the parameters for the development of high strength low alloy steels for transporting gas and oil at lower cost and safely. In this context, this research investigates, in a microalloyed steel pipe API 5L X80, the effect of phase transformations obtained by controlled cooling on the behavior when loaded with hydrogen - Hydrogen Induced Cracking - (HIC) and in the mechanical properties. HIC tests were performed on as-received material, on samples extracted from the thickness of the plate and subjected to continuous cooling and on samples of the material treated to simulate the coarse-grained regions of heat affected zone (CGHAZ). According to the cooling cycle, the microalloyed steels have complex microstructures: in the steel under evaluation its microstructure, studied in a previous work, consists mainly of ferrite, bainite, pearlite and austenite/martensite constituent (AM). The morphology, size, quantity and distribution of the products of transformation change the properties of plate steel. These phenomena are of great technological interest in microalloyed steels for the fabrication of welded tubes for the transport of gas and oil, when the welding is performed in the field as well as during hot bending; here the mechanical properties of the tube from the process of thermomechanical fabrication can be degraded by the action of heating and cooling experienced in the heat affected zone (HAZ), mainly in the region of CGHAZ. Simulations of thermal cycles for the study of HIC on sheet thickness were performed in coupons subjected to austenitization at 900ºC followed by continuous cooling in the dilatometer. To simulate the thermal cycles with controlled cooling, focused in the CGHAZ, and getting suitable sample sizes for tensile testing and Charpy, it was necessary to austenitize at 1300ºC followed by continuous cooling using the thermal and thermomechanical simulator in a Gleeble dilatometer. Samples heat treated in this equipment were suitable to evaluate the mechanical properties and the HIC of the material for different regions of HAZ, while a real weld would not have enough material to allow this type of testing on a specific region of HAZ. The results showed the susceptibility of each microstructure product of austenite transformation and of the position on the plate thickness. The central region of the plate was more sensitive to hydrogen in the steel as-received and when treated at low cooling rates of 0.5°C/s after austenitization at 900°C. The bands formed by coarse structures of greater hardness than the matrix in the central region decreased the resistance to HIC. Likewise in coupons that simulate the CGHAZ region, the fracture induced by hydrogen was located in the central thickness line, even when the microstructure were bainite and acicular ferrite. Failure there was possibly due to remnants of segregated elements in this central region and carbon partition to the subboundaries of the bainite and ferrite grain that grew from the primary austenite. Inclusions and precipitates, according to their type, shape and location in the microstructure, participating or not in the nucleation and propagation of the crack, were more critical when located within the banded structures; crack nucleation in the presence of hydrogen was not observed at Nb and Ti precipitates.

La chromatographie en phase liquide bidimensionnelle « comprehensive » en ligne (LCxLC) est une technique à très haut pouvoir de séparation. Après avoir établi son intérêt mais aussi les enjeux liés au développement de méthodes et les conditions expérimentales utilisées, une attention particulière est portée à l'optimisation des méthodes en LCxLC. Une procédure d'optimisation basée une méthode « Pareto-optimal » est décrite. Les conditions optimales prédites sont ensuite appliquées à la séparation RPLCxRPLC d'un mélange complexe de peptides et comparée avec la 1D-RPLC en termes de capacité de pics, temps d'analyse et facteur de dilution démontrant l'avantage fournit par la RPLCxRPLC. L'optimisation d'une méthode HICxRPLC-UV/MS en ligne permettant la caractérisation exhaustive d'un anticorps conjugué est réalisée soulignant, entre autres, la grande complémentarité entre les différents modes de détection employés en 1D et 2D.Enfin, la possibilité de développer un couplage RPLCxSFC est explorée dans le but d'augmenter l'espace de séparation pour des composés neutres. La méthode RPLCxSFC optimisée est comparée avec une séparation RPLCxRPLC optimisée pour l'analyse d'une bio-huile montrant qu'elle peut-être considérée comme une alternative crédible pour la séparation de tels échantillons / Comprehensive two-dimensional liquid chromatography is a powerful but complex separative technique. After detailing the interest of such a technique, the method development issues and the experimental conditions employed throughout this work, a particular attention is paid to the optimization of LCxLC methods. Accordingly an optimization procedure based on Pareto-optimal method is described. The predicted optimal conditions are then applied to experimental RPLCxRPLC separations of complex samples of peptides and compared with 1D-RPLC in terms of peak capacity, analysis time and sensitivity clearly showing the advantage of RPLCxRPLC approach.The optimization of a HICxRPLC-UV/MS method for the exhaustive characterization of an antibody-drug conjugate is achieved highlighting the high complementarity of the different detection modes used both in 1D and 2D. Finally, a proof of concept concerning the implementation of RPLCxSFC coupling is achieved with the aim of increasing the separation space coverage for neutral compounds. The optimized RPLCxSFC separation is then compared with an optimized RPLCxRPLC approach for the analysis of a bio-oil sample showing that RPLCxSFC is a credible alternative for the separation of such a sample

L'objectif de ce travail est de prédire les risques de fissuration par H2S d'aciers au carbone à très haute limite d'élasticité utilisés en environnement pétrolier. Nous nous intéressons aux conditions de sévérité modérées, caractérisées par des teneurs faibles mais non nulles en H2S dans le milieu corrosif. Dans ces environnements, le chargement en hydrogène dans les aciers est lent, et les temps d'incubation avant apparition de fissures internes de type HIC peuvent donc être longs. En complément des essais standards de tenue à la fissuration des aciers, il est donc important de pouvoir disposer de méthodes rapides et fiables d'évaluation des risques de fissuration. La principale technique expérimentale mise en oeuvre est la perméation électrochimique d'hydrogène. Elle est mise à profit afin d'étudier le chargement, la diffusion et le piégeage de l'hydrogène dans différents aciers à haute limite d'élasticité en environnement faiblement concentré en H2S. En complément des essais de perméation, nous effectuons une étude de la fissuration assistée par l'environnement dans différentes conditions de pH et de PH2S. Ces essais permettent d'abord de vérifier l'évolution de la cinétique de fissuration interne en fonction des conditions environnementales. Dans le même temps, nous réalisons des mesures de la quantité d'hydrogène absorbée par le métal, en distinguant les parts d'hydrogène libre, piégé réversiblement et irréversiblement. La confrontation entre les données de diffusion et de piégeage issues des essais de perméation, et des données directes de fissuration et de quantités d'hydrogène absorbé permet l'établissement de seuils de concentrations critiques en hydrogène. Ces seuils sont ensuite utilisés afin de mettre en place une approche empirique prédictive de la fissuration HIC dans les aciers / The work of this thesis applies to flexible pipelines, which are used as risers or flowlines in offshore production. More specifically, it is dedicated to study the risks of hydrogen embrittlement of carbon steel wires used as armors if flexible pipes. The study is focused on low H2S containing medium inducing slow hydrogen entry in steels, thus, potentially long incubation times before embrittlement becomes effective. The first goal of this work is to study the entry, diffusion and trapping of hydrogen into different grades of carbon steel in low H2S concentration environment. The permeation technique will be used, as well as immersion tests of variable duration with characterization of the crack process. Analysis of permeation transients gives information on hydrogen diffusion and hydrogen trapping into steels in function of experimental conditions (pH, PH2S). Immersion tests will be performed complementary to permeation tests in various conditions of pH and PH2S. We verify the cracking evolution with environmental conditions. We also quantify the lattice hydrogen, the reversibly and irreversibly trapped hydrogen absorbed by the materials. Then, using both diffusion properties from permeation tests and cracking data from immersion experiments, we set up a predictive approach to link the risks of H2S cracking for each steel grade in function of the severity of the environment. Applying this method should also allow to establish faster and more reliable comparisons of the hydrogen induced cracking resistance of different steel grades. It should be used as complimentary tool for qualification purposes

Wasserstoff-induzierte Schäden sind ein verbreitetes Problem in verschiedenen Anwendungen von Metallen. In dieser Arbeit wurde Wasserstoff-induzierte Rissbildung in Eisen untersucht. Die Proben wurden elektrochemisch mit Wasserstoff beladen. Diese Beladung führt zu Rissen in den Eisenproben und Blistern auf deren Oberfläche, wenn Risse oberflächennah lokalisiert sind. Als Triebkraft der Rissbildung wurde der hohe Wasserstoffdruck in den Rissen gefolgert. Dieser Druck wurde durch eine Kombination aus Ausgasexperimenten und Dichtemessungen bestimmt. Die Mikrostruktur, die Risse und Blister umgibt, wurde mit Elektronenmikroskopie untersucht. Dafür wurden Rissflächen durch Zugversuche freigelegt. Oxidische Einschlüsse konnten als Ausgangspunkt für Risse ausgemacht werden. Mit Transmissionselektronenmikroskopie wurden duktile Merkmale in der Nähe von Rissen sichtbar. Ein Mechanismus für die Riss- und Blisterbildung wurde vorgeschlagen.

Aços de alta resistência e baixa liga (ARBL) têm sido bastante utilizados na fabricação de tubulações para o transporte de petróleo e gás. Entretanto, o uso destes materiais em meios com elevadas concentrações de H2S, denominados sour, tem resultado em falhas frequentes, devido à suscetibilidade destes materiais ao desenvolvimento do fenômeno de trincamento induzido pelo hidrogênio (Hydrogen Induced Cracking - HIC), assim como devido a problemas de corrosão. O desenvolvimento de diferentes processos tecnológicos para a produção de tubos de aços ARBL, tais como a laminação controlada e resfriamento acelerado, a adição de microligantes, assim como a diminuição do teor de enxofre, fósforo, carbono e manganês, tem levado à elaboração de materiais com propriedades mecânicas otimizadas, permitindo também um melhor controle da microestrutura. As perdas de dureza e resistência mecânica devidas à redução do teor de manganês, são compensadas pela adição de elementos como cromo e nióbio. Neste trabalho estão sendo comparadas a resistência à corrosão e os parâmetros de permeabilidade do hidrogênio de dois tubos de aço API 5L X65 e uma chapa API 5L X65, todos do tipo ARBL e com baixo manganês (0,27%) e alto nióbio (0,083% a 0,090%), na solução B da norma NACE, TM-0284 (2011). Para isto, foram realizados ensaios de potencial de circuito aberto (Open Circuit Potential - OCP), espectroscopia de impedância eletroquímica (Electrochemical Impedance Spectroscopy - EIS) e curvas de polarização potenciodinâmicas no eletrólito naturalmente aerado, desaerado e saturado com H2S. Os testes de permeabilidade do hidrogênio foram realizados com base na norma ASTM INTERNATIONAL G148 - 97, porém usando a célula modificada de DEVANATHAN e STACHURSKY (1962) e com H2S como veneno catódico. Os materiais foram caracterizados por microscopia óptica (MO), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva de Raios-X (X-Ray Energy Dispersive Spectroscopy - EDS) antes e depois de testes de imersão nos diferentes eletrólitos. Caracterização dos produtos de corrosão por difração de raios-X (DRX) também foi realizada após imersão em meio saturado com H2S (sour). As análises por MO e MEV mostraram matrizes ferríticas para os três aços, com a presença de baixos teores do microconstituinte martensita/austenita (M/A), de perlita e com baixo nível de inclusões uniformemente distribuídas e com composições químicas semelhantes. Os resultados dos ensaios de corrosão mostraram que, para todos os meios investigados, o aço denominado como B apresentou a melhor resistência à corrosão, enquanto aquele denominado como C se mostrou o mais suscetível em todas as condições estudadas. Para os três aços, a resistência à corrosão apresentou a seguinte ordem crescente de acordo com o meio de exposição: meio saturado com H2S < meio naturalmente aerado < meios desaerados. Ensaios de OCP e EIS no meio saturado com H2S em um período de 24h mostraram que a resistência à corrosão aumenta com o tempo em razão da formação de uma camada de sulfeto de ferro, que, no entanto, se apresentou pouco aderente. Os resultados dos ensaios de permeação de hidrogênio mostraram que o aço denominado B, que apresentou maior resistência à corrosão em todos os meios e que não apresenta perlita em sua microestrutura, teve o maior valor de difusividade efetiva de hidrogênio, menor concentração de hidrogênio atômico na sub-superfície e menor quantidade de traps por unidade de volume. Quanto aos outros dois materiais, os resultados dos testes de permeabilidade ficaram em desacordo com os resultados da caracterização microestrutural e dos testes de resistência à corrosão, indicando que fatores diferentes dos detectados neste estudo são importantes para governar essas propriedades. / High strength low alloy (HSLA) steels have been widely used in the manufacture of pipelines for the transport of oil and gas. However, the application of these steels in media with high H2S concentrations, denominated sour, has resulted in frequent failures due to the susceptibility of these materials to the development of Hydrogen Induced Cracking (HIC) phenomena, as well as due to corrosion problems. The development of different technological processes for HSLA piping production, like controlled rolling and accelerated cooling, the addition of microalloying elements, as well as the reduction of the amounts of sulphur, phosphorus, carbon and manganese, has led to the development of materials with optimized mechanical properties, also allowing a better microstructural control. Hardness and mechanical resistance reduction due to the lowering of Mn content are compensated by niobium and chromium addition. In this work, the corrosion resistance and the hydrogen permeability parameters of two API 5L X65 steel tubes and an API 5L X65 plate, all HSLA type and with low manganese (0.27%) and high niobium (0.083% to 0.090%) contents, are compared in solution B of NACE standard TM-0284 (2011). For this, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves were carried out in the naturally aerated, deaerated and H2S saturated electrolyte. Hydrogen permeability tests were performed based on ASTM INTERNATIONAL G148-97, but using a modified DEVANATHAN and STACHURSKY (1962) cell and with H2S as cathodic poison. The materials were characterized by means of optical microscopy (OM), scanning electron microscopy (SEM) and X-Ray Energy Dispersive Spectroscopy (EDS) prior and after immersion tests in the different electrolytes. Characterization of the corrosion products by X-ray diffraction (XRD) was also performed after immersion in the H2S-saturated (sour) medium. The OM and SEM characterization showed ferritic matrices for the three steels, with the presence of low levels of the martensite/austenite (M/A) microconstituent, perlite and with a low level of inclusions evenly distributed and with similar chemical compositions. The results of the corrosion tests showed that, for all investigated media, the steel denominated as B presented the best resistance to corrosion, whereas the one denominated as C showed to be the most susceptible in all the conditions studied. For the three steels, the corrosion resistance showed the following ascending order according to the exposure medium: H2S saturated < naturally aerated medium < deaerated media. OCP and EIS tests in the H2S-saturated medium in a period of 24 hours showed that the corrosion resistance increases over time due to the formation of an iron sulphide layer, which, however, presented little adhesion. The results of the hydrogen permeation tests showed that the steel denominated B, that presented greater corrosion resistance in all media and that does not present perlite in its microstructure, had the highest values of effective hydrogen diffusivity, the lowest concentration of atomic hydrogen in the subsurface and the smallest amount of traps per unit volume. Concerning the other two materials, the results of the permeability tests were at variance with the results of the microstructural characterization and corrosion resistance tests, indicating that factors other than those detected in this study are important to govern such properties.

Endometriosis is one of the most common gynecological diseases as it is thought to affect up to 15% of the female population. Characterized by the growth and proliferation of endometrial tissue outside of the uterine cavity, it is a complex condition with varying degrees of severity and can affect multiple regions of the body with symptoms ranging from a total lack of symptoms to debilitating pain and infertility. The most accepted theory of how endometriosis initiates is that of retrograde menstruation; however, approximately 90% of women with unobstructed fallopian tubes are thought to have some menstrual debris in the peritoneal cavity. Therefore, this theory does not explain in full why endometriosis occurs in some but not all women who experience retrograde bleeding. Genetic factors are thought to play a major role in the pathogenesis of endometriosis as women with a family history are 5 to 10 times more likely to develop the disease. The goal of this study was to determine if common chromosomal aberrations in the form of additions, deletions, or regions of loss of heterozygosity that may contribute to the establishment or progression of the disease are present in a population of endometriosis patients. DNA was isolated from the peripheral blood of endometriosis patients and endometriosis tissue biopsies, and it was analyzed using oligonucleotide based array comparative genomic hybridization. The results suggest that an addition on chromosome 17p13.3 may play a role in the biological mechanisms involved in endometriosis as it was identified in 75% of the DNA samples obtained from the peripheral blood and 100% of the DNA samples obtained from the tissue biopsies. This chromosomal imbalance is of particular interest as it is located in a region that harbors the tumor suppressor gene, hypermethylated in cancer-1 (HIC-1), whose aberrant expression has been reported in multiple cancers. Endometriosis has long been thought of as a benign disease despite its malignant characteristics, and individuals with endometriosis have been demonstrated to have an increased chance of developing ovarian cancer. This was the first study to examine the DNA from endometriosis patients using oligonucleotide based array comparative genomic hybridization to investigate genetic abnormalities in endometriosis. The findings may provide a novel target for future therapeutic options as well as indicate a link between endometriosis and cancer that has not been previously reported.

Falls among the elderly population continue to be a growing concern in the healthcare industry and are marked by staggeringly high social and economic costs. The incidence of falls is known to increase with age, and currently the elderly population is growing at an astounding rate as baby-boomers are now entering this age group. Also, recovery following fall-related injuries decreases with increased age. These confounding factors currently make falls a very important area of research. Of the injuries typically seen in falls among the elderly, head injuries are one of the most debilitating. Death due to head trauma among the elderly is gaining national attention; head trauma is now considered the number one cause of death among elders who fall1. Among other technologies, medical helmets are often employed to protect against such injuries, but patient compliance with these helmets remains an issue. Current helmets use foams and cotton as padding, contributing to clumsy designs. Dilatent and honeycomb materials may be the future of this industry as their low weight and high efficacy per thickness make them ideal materials for thinner, lighter, less cumbersome head protection devices. This study outlines various modes of head injury and then highlights several head protection measures. The newer materials are tested using various methods to determine the most promising candidates for prototype designs. Next, three prototypes are assembled from the newer materials and compared directly based on the protection measures established. Finally, the top-performing prototype is compared against two existing medical helmets in a similar fashion. The results show that the best prototype significantly outperforms one of the existing medical helmets, and shows slight improvement over the other. These results establish the promise of these newer materials in the application of head protection devices.