Modelagem dinâmica e simulação computacional de poços de petróleo verticais e direcionais com elevação por bombeio mecânico

LINS, Filipe C. A. et al. Modelagem dinâmica e simulação computacional de poços de petróleo verticais e direcionais com elevação por bombeio mecânico. In: CONGRESSO BRASILEIRO DE PESQUISA E DESENVOLVIMENTO EM PETRÓLEO E GÁS, 5. 2009, Fortaleza, CE. Anais... Fortaleza: CBPDPetro, 2009.

Desacoplamento mitocondrial e estresse oxidativo em espermatozoides suínos resfriados

A espécie suína (Sus scropha domesticus) possui relevância nos âmbitos da pesquisa, da xenotransplantação e da produção de carnes. O resfriamento de sêmen é capaz de reduzir o metabolismo celular e possibilitar o armazenamento dos gametas, sendo auxiliar durante práticas de reprodução assistida. Contudo, os espermatozoides suínos são sensíveis ao estresse oxidativo gerado durante o processo de resfriamento. O 2,4 dinitrofenol (DNP) poderia gerar o desacoplamento mitocondrial reduzindo o estresse oxidativo e prolongando indiretamente a viabilidade e capacidade fertilizante de espermatozoides suínos resfriados pela diminuição de espécies reativas de oxigênio. O objetivo do presente estudo foi avaliar os efeitos do desacoplamento mitocondrial induzido pelo DNP e os efeitos desse desacoplamento sobre as de fluidez e integridade de membrana plasmática, funcionalidade de mitocôndria, motilidade espermática, além dos parâmetros de estresse oxidativo de lipoperoxidação e produção de espécies reativas de oxigênio, durante o resfriamento a 17 °C de 24 até 96 horas. Utilizou-se 22 ejaculados expostos ao diluente Betsville Thawing Solution (BTS) (controle) e ao mesmo diluente acrescido das concentrações de 0,01 µM (T1); 0,1 µM (T2); 1,0 µM (T3) e 10 µM (T4) de DNP. Através do teste de Shapiro-Wilk as variáveis que não apresentaram normalidade, tiveram suas médias comparadas pelo teste de KruskalWallis. As análises estatísticas demonstraram que o DNP não se diferiu do controle independente do tempo de armazenamento, para nenhuma das variáveis analisadas. Possivelmente, a falta de ação sobre as mitocôndrias, ou seja, a não promoção do desacoplamento mitocondrial foi o motivo principal para a falta dos efeitos do DNP. Acredita-se que a utilização do DNP em temperaturas mais elevadas por estas promoverem aumento da fluidez de membrana e/ou o aumento das concentrações de DNP poderiam gerar efeitos significativos sobre as mitocôndrias e demais variáveis analisadas. Finalmente, o DNP nas concentrações testadas não se diferiu do controle em todas as variáveis analisadas independente do tempo de armazenamento.

Modelo de regressão beta para teste de estresse em risco de crédito de instituições financeiras

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Estatistica, 2015.

GERMINAÇÃO DE SEMENTES DE Piptadenia moniliformis Benth. SOB ESTRESSE HÍDRICO

O período de germinação e o estabelecimento de plântulas é um dos fatores mais importantes para a sobrevivência das espécies, principalmente nos locais em que a disponibilidade de água é limitada, como na região da Caatinga. Neste sentido, o objetivo deste trabalho foi avaliar o efeito do estresse hídrico sobre a germinação de sementes de Piptadenia moniliformis Benth. Foram utilizados três lotes (L1, L2 e L3), correspondentes aos anos de produção de 2006, 2007 e 2008, respectivamente. Antes do teste de germinação, as sementes foram escarificadas com ácido sulfúrico concentrado durante 30 minutos. Para induzir o deficit hídrico, foi utilizado o polietileno glicol (PEG 6000), nos seguintes potenciais osmóticos: - 0,3; -0,6; -0,9, -1,2 e -1,5 MPa e a água (0 MPa) sob as temperaturas de 25 e 30ºC. As características avaliadas foram: porcentagem de germinação e de plântulas normais, índice de velocidade de germinação e massa seca de plântulas. O processo germinativo de sementes de Piptadenia moniliformis Benth. é comprometido a partir de potenciais hídricos inferiores a -0,6 MPa a 25 e 30 °C; potenciais hídricos iguais ou inferiores a -1,2 MPa inibem a formação de plântulas normais nas duas temperaturas; a tolerância ao estresse hídrico simulado com PEG 6000 é variável entre lotes de sementes e temperaturas de germinação.

Diseño mecánico de los elementos de transmisión de un aerogenerador de 1, 3 MW

Partiendo de la potencia que ha de generar se pretende realizar el diseño de los distintos elementos de transmisión de un aerogenerador con el fin de garantizar un funcionamiento óptimo del mismo.

Estudo do estresse oxidativo e expressão da aromatase e receptor relacionado ao estrógeno gama na placenta humana

 Introdução: Durante a gravidez, devido ao aumento da exigência metabólica placentária há um aumento na produção das espécies reativas de oxigénio (ROS) que podem causar, por exemplo, oxidação de ácidos graxos poli-insaturados na placenta, além disso, nesta fase ocorre um aumento na expressão da aromatase e do receptor relacionado ao estrógeno gama (ERRgama) na placenta humana. Objetivo: O objetivo do estudo foi avaliar os parâmetros de estresse oxidativo e imunomarcação da aromatase e do ERRgama na placenta humana. Métodologia: A capacidade antioxidante total (ACAP), atividade da glutamato cisteína ligase (GCL), concentração glutationa (GSH), peroxidação lipídica e imunomarcação da aromatase e do ERRgama foram analisados em tecido placentário de 58 parturientes. Estas análises foram relacionadas com os dados socio-demográficos das participantes. Resultados: Os recém-nascidos de mães fumantes nasceram com menor peso (p=0,001). A concentração de GSH diminuiu a produção da peroxidação lipídica (p<0,05), por outro lado, a atividade de GCL teve efeito oposto (p<0,001). Encontramos uma diminuição na capacidade antioxidante total e aumento da peroxidação lipídica (p<0,05) na placenta. A placenta de mães fumantes tinham menos marcação da aromatase (p=0,037) já, as mães mais velhas tiveram menos marcação do ERRgama (p=0,009) na placenta. A GSH teve efeito positivo na imunomarcação de ERRgama (p=0,001). Conclusões: A expressão da aromatase e do ERRgamma na placenta são alterados tanto por fatores exógenos, tais como o fumo do cigarro, como por fatores endógenos, tais como a concentração de GSH e a idade da mãe. Os marcadores de estresse oxidativo na placenta são mais elevados em mães mais velhas e em placenta com menor capacidade antioxidante total. 

Avaliação do estresse oxidativo induzido por superfícies de titânio

Commercially pure Titanium (cp Ti) is a material largely used in orthopedic and dental implants due to its biocompatibility properties. Changes in the surface of cp Ti can determine the functional response of the cells such as facilitating implant fixation and stabilization, and increased roughness of the surface has been shown to improve adhesion and cellular proliferation. Various surface modification methods have been developed to increase roughness, such as mechanical, chemical, electrochemical and plasma treatment. An argon plasma treatment generates a surface that has good mechanical proprieties without chemical composition modification. Besides the topography, biological responses to the implant contribute significantly to its success. Oxidative stress induced by the biomaterials is considered one of the major causes of implant failure. For this reason the oxidative potential of titanium surfaces subjected to plasma treatment was evaluated on this work. CHO-k1 cells were cultivated on smooth or roughed Ti disks, and after three days, the redox balance was investigated measuring reactive oxygen species (ROS) generation, total antioxidant capacity and biomarkers of ROS attack. The results showed cells grown on titanium surfaces are subjected to intracellular oxidative stress due to hydrogen peroxide generation. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular ability. Our data suggest that plasma treated titanium may be a more biocompatible biomaterial.

Identificação de genes em Chromobacterium violaceum relacionados à resposta ao estresse

The sequencing of the genome of Chromobacterium violaceum identified one single circular chromosome of 4.8 Mb, in which approximately 40% of the founded ORFs are classified as hypothetical conserved or hypothetical. Some genic regions of biotechnological and biological interest had been characterized, e. g., environmental detoxification and DNA repair genes, respectively. Given this fact, the aim of this work was to identify genes of C. violaceum related to stress response, as the ones involved with mechanisms of DNA repair and/or genomic integrity maintenance. For this, a genomic library of C. violaceum was built in Escherichia coli strain DH10B (RecA-), in which clones were tested to UVC resistance, resulting in five candidates clones. In the PLH6A clone were identified four ORFs (CV_3721 to 3724). Two ORFs, CV_3722 and CV_3724, were subcloned and a synergic complementation activity was observed. The occurrence of an operon was confirmed using cDNA from C. violaceum in a RT-PCR assay. Further, it was observed the induction of the operon after the treatment with UVC. Thus, this operon was related to the stress response in C. violaceum. The mutagenesis assay with rifampicin after the treatment with UVC light showed high frequency of mutagenicity for the ORF CV_3722 (Pol III δ subunit). In this way, we propose that the C. violaceum δ subunit can act in DH10B in the translesion synthesis using Pol IV in a RecA independent-manner pathway. In growth curve assays other four clones (PLE1G, PLE7B, PLE10B and PLE12H) were able to complement the function at the dose 5 J/m2 and in mutagenicity assays PLE7B, PLE10B and PLE12H showed frequencies of mutation with significant differences upon the control (DH10B), demonstrating that in some way they are involved with the stress response in C. violaceum. These clones appear to be interrelated, probably regulated by a messenger molecule (eg., nucleotide c-di-GMP) and/or global regulatory molecule (eg., σS subunit of RNA polymerase).The results obtained contribute for a better genetic knowledge of this specie and its response mechanisms to environmental stress.

Proteômica diferencial da Chromobacterium violaceum em resposta ao estresse oxidativo induzido por peróxido de hidrogênio

The β-proteobacterium Chromobacterium violaceum is a Gram-negative, free-living, saprophytic and opportunistic pathogen that inhabits tropical and subtropical ecosystems among them, in soil and water of the Amazon. It has great biotechnological potential, and because of this potential, its genome was completely sequenced in 2003. Genome analysis showed that this bacterium has several genes with functions related to the ability to survive under different kinds of environmental stresses. In order to understand the physiological response of C. violaceum under oxidative stress, we applied the tool of shotgun proteomics. Thus, colonies of C. violaceum ATCC 12472 were grown in the presence and absence of 8 mM H2O2 for two hours, total proteins were extracted from bacteria, subjected to SDS-PAGE, stained and hydrolysed. The tryptic peptides generated were subjected to a linear-liquid chromatography (LC) followed by mass spectrometer (LTQ-XL-Orbitrap) to obtain quantitative and qualitative data. A shotgun proteomics allows to compare directly in complex samples, differential expression of proteins and found that in C. Violaceum, 131 proteins are expressed exclusively in the control condition, 177 proteins began to be expressed under oxidative stress and 1175 proteins have expression in both conditions. The results showed that, under the condition of oxidative stress, this bacterium changes its metabolism by increasing the expression of proteins capable of combating oxidative stress and decreasing the expression of proteins related processes bacterial growth and catabolism (transcription, translation, carbon metabolism and fatty acids). A tool with of proteomics as an approach of integrative biology provided an overview of the metabolic pathways involved in the response of C. violaceum to oxidative stress, as well as significantly amplified understanding physiological response to environmental stress. Biochemical and "in silico" assays with the hypothetical ORF CV_0868 found that this is part of an operon. Phylogenetic analysis of superoxide dismutase, protein belonging to the operon also showed that the gene is duplicated in genome of C. violaceum and the second copy was acquired through a horizontal transfer event. Possibly, not only the SOD gene but also all genes comprising this operon were obtained in the same manner. It was concluded that C. violaceum has complex, efficient and versatile mechanisms in oxidative stress response

Influência do teor de calcário no comportamento físico, mecânico e microestrutural de cerâmicas estruturais

There are ores of clay in Piauí State that are used for red structural ceramics, which are naturally contaminated with calcareous vein. This is one thing that impedes its exploration in an adequate way, especially for tile production. The present work aims at verifying the influence of the calcareous contents in the technological structural ceramics area, seeking to determine a maximum permissible calcareous proportion/contents in the ceramic mass using the patterns of the local industry production. For the consecution of this paper, it was characterized the clay and calcareous material by FRX, DRX, TGA and DTA. It was also configurated by extrusion and burnt in the temperatures of 850°C, 900°C, 950°C and 1000°C pieces of the corpus with 0, 5, 10, 15 e 20% of calcareous proportion. After that, it was carried out technological samples of linear retraction, water absortion, apparent porosity, specific apparent mass and mechanic resistance. The results showed the possibility of using calcareous in the ceramic mass and in some cases the technological properties got better

Estudo do comportamento plástico, mecânico, microestrutural e térmico do concreto produzido com resíduo de porcelanato

Population growth experienced in major cities, allied to society s need of infra-structure, especially ones related to habitational demands, increases the consumption of construction materials. As a consequence, consumption of natural resources itself. Thus, due to this process, concrete is one of the most produced materials in civil construction. This is also due to the great diversity of its application, easiness in its execution and adequate mechanical performance, as well as low production costs. Following the same tendencies in construction development, the ceramic industry has intensified the production of porcelain ceramic tiles and floors. These are achieved by a fine finishing and receive polishing at the end of the fabrication process. This work researched the use of porcelain residues in polishing for the production of concrete. All of which; due to economical and environmental issues. This process aims to prove adequate destiny for this type of residue, due to environmental issues, incorporating it to the concrete itself; all of which provides economy in consumption of the materials that constitute concrete. Thus, the main characteristics of concrete were investigated through the inclusion of different concentration of the porcelain residue as additional trait element. The residue rates incorporated to the trait varied from 10% to 50% in relation to the cement mass, in the traits with plastic additives and without plastic additives. It is observed that the inclusion of porcelain residue produced a meaningful alteration in the consistency of fresh concrete. This residue has a fine granulometry and it considerably absorbed the water used in the concrete spreading, influencing the way this material is dealt with. Thus, the value of cement striking decreases with the increase of residues present in trait. The maximal incorporation of the residue was of 50%, massively, for the same factor water/initial cement. The use of residues in concrete results in an 40% increase in the compression resistance. It is also proportional to residue concentration of porcelain in the trait. The microstructure was also favored once porosity and concrete absorption decreases with the use of this residue. The parameters demonstrate the quality and durability of the concrete produced with this residue. The use of porcelain residue in concrete composition has not produced meaningful thermal behavior changes. Thermal conductivity, heat capacity and thermal diffusivity have been maintained basically constant