The biodegradation kinetics of Geropon TC-42 (trademark) by an acclimated culture was investigated in anoxic batch reactors to determine biokinetic coefficients to be implemented in two biofilm mathematical models. Geropon TC-42 (trademark) is the surfactant commonly used in space habitation. The two biofilm models differ in that one assumes a constant biofilm density and the other allows biofilm density changes based on space occupancy theory. Extant kinetic analysis of a mixed microbial culture using Geropon TC-42 (trademark) as sole carbon source was used to determine cell yield, specific growth rate, and the half-saturation constant for S0/X0 ratios of 4, 12.5, and 34.5. To estimate cell yield, linear regression analysis was performed on data obtained from three sets of simultaneous batch experiments for three S0/X0 ratios. The regressions showed non-zero intercepts, suggesting that cell multiplication is not possible at low substrate concentrations. Non-linear least-squares analysis of the integrated equation was used to estimate the specific growth rate and the half-saturation constant. Net specific growth rate dependence on substrate concentration indicates a self-inhibitory effect of Geropon TC-42 (trademark). The flow rate and the ratio of the concentrations of surfactant to nitrate were the factors that most affected the simulations. Higher flow rates resulted in a shorter hydraulic retention time, shorter startup periods, and faster approach to a steady-state biofilm. At steady-state, higher flow resulted in lower surfactant removal. Higher influent surfactant/nitrate concentration ratios caused a longer startup period, supported more surfactant utilization, and biofilm growth. Both models correlate to the empirical data. A model assuming constant biofilm density is computationally simpler and easier to implement. Therefore, a suitable anoxic packed bed reactor for the removal of the surfactant Geropon TC-42 (trademark) can be designed by using the estimated kinetic values and a model assuming constant biofilm density.

Background: Sex and stress steroids are metabolized to 3a-hydroxy-pregnane-steroid metabolites such as allopregnanolone (Allo) and tetrahydrodeoxycorticosterone (THDOC). Allo and THDOC are neuroactive steroids that are metabolized in the brain and act in brain as potent positive GABAA receptor function modulators. Allo as well as THDOC levels increase during stress. Allo has been associated with a number of symptoms and malfunctions such as impaired memory function and negative mood symptoms in a subgroup of individuals both for animals and humans. Pregnane steroids with 3b-hydroxy-configuration (3b-steroids) have been shown to reduce the Allo enhanced GABA effect. Aims: The aims for the present thesis were to investigate the effect of 3b-steroids on the GABA mediated GABAA receptor function in presence of positive GABAA receptor modulators. Further, the regional variances between the 3b-steroids as well as the mechanism of the effect were studied. Finally, the effect of stress steroid metabolites on the GABAA receptor function was investigated. Results: 3b-OH-5a-pregnane-20-one reduced the Allo enhanced GABA mediated chloride ion uptake into cortical microsacs. The 3b-isomer reduced the efficacy of Allo without shift the concentration response curve. It is therefore suggested that the 3b-isomer has a non-competitive effect. Further, it was shown that the 3b-isomer reduced the Allo effect in a selective way since the 3b-isomer did not interact with other positive modulators or with GABA itself. Five tested 3b-steroids reduced the Allo enhanced GABA mediated chloride ion uptake in cerebral cortex and hippocampus as well as the Allo prolongation on spontaneous inhibitory postsynaptic currents (sIPSCs) in preoptic nucleus. In cerebellum on the other hand the 3b-steroids showed to have weaker or no effect compared to the other tested regions. Interestingly, in absence of Allo, two of the 3b-steroids positively modulated the GABA stimulated GABAA receptor function. In absence of Allo, 5b-pregnane-3b,20(R)-diol increased the desensitization rate of current response. In contrast to the reducing effect on the Allo induced prolongation on sIPSCs, the effect of the 3b-steroid on GABA application, was not altered in presence of Allo. The mechanism of the 3b-steroid is therefore suggested being desensitization dependent in contrast to Allo, which has been suggested to decrease the GABA unbinding rate. In contrast to the enhanced effect of Allo, glucocorticoid metabolites reduced the GABA mediated chloride ion uptake in a concentration dependent way. The results in present thesis indicate that both sex and stress steroid metabolites interact with the GABAA receptor function. The knowledge that diversity of endogenous steroids interact with the GABAA receptor function is of importance for further understanding of different sex and stress steroid related symptoms and syndromes.

O estudo de parâmetros cinéticos para a queima de carvão se dá através de utilização de equipamentos laboratoriais como o forno de queda livre (DTF). O presente trabalho trata do desenvolvimento e análise de um modelo numérico unidimensional de um DTF. A modelagem é realizada a partir de dados da literatura, e as equações discretizadas que caracterizam os fenômenos do escoamento, da transferência de calor e da combustão do carvão foram programadas na linguagem FORTRAN 90. Os resultados são comparados com um modelo de referência e com dados experimentais, e apresentaram boa concordância. Um estudo de sensibilidade é realizado para entender o comportamento da queima de carvão frente a mudanças de alguns parâmetros de operação do DTF. A análise de sensibilidade mostrou a versatilidade do modelo e, consequentemente, do experimento. A partir da variação da concentração de O2, da temperatura de operação e das vazões de entrada pode-se obter uma gama de resultados. O uso do modelo aqui apresentado concomitante com resultados experimentais resulta em um estudo aprofundado dos parâmetros cinéticos de combustão de carvão. / The study of kinetic parameters for coal combustion occurs through use of laboratory equipment such as drop tube furnace (DTF). The present work shows the development and analysis of a one-dimensional numerical model of a DTF. The modeling is developed from literature works, and the discrete equations that characterize the flow, heat transfer and coal combustion are programmed in FORTRAN 90 language. The results are compared with a reference model and experimental data, and showed good agreement. A sensitivity study is performed to understand the behavior of coal combustion due to changes of some working parameters of the DTF. The sensitivity analysis showed the versatility of the model and thereby the experiment. From the variation of the O2 concentration, operating temperature and input flow rates a range of results can be obtained. Using the model presented here together with experimental results leads to a detailed study of the kinetic parameters of coal combustion.

The thrombogenic process that affects the hypertensive patient is associated with regulatory mechanisms present in the vascular endothelium. These mechanisms involve the release of a endothelium-derived relaxing factor, ectonucleotidases and calcium ions. Considering that vasodilators act both on blood pressure and on homeostasis, we evaluated the interference of different vasodilators on platelet NTPDase activity in hypertensive and healthy patients, with the objective of verifying patient sensitivity to vasodilators. In addition, the kinetic behavior of NTPDase was determined in the presence of the vasodilator that showed the greatest inhibitory influence. The results showed a decrease in NTPDase activity in the presence of arginine (0.025 mM 3.0 mM), sodium nitroprusside (0.01 mM 2.0 mM) and hydralazine (20.0 μM 90.0 μM), when tested for ATP and ADP substrate. However, the hydrolysis of ATP and ADP substrates increased when tested in the presence of arginine in the control group. No effects on enzyme activities were observed when pharmacological doses of captopril were tested in vitro. Kinetic behavior studies were estimated in the presence of sodium nitroprusside, which caused a mixed inhibition. The Km values increased and Vmax decreased with increasing sodium nitroprusside concentrations. The IC50 values were 3.66 mM and 2.64 mM (control group) and 2.08 mM and 3.15 mM (hypertensive group) for ATP and ADP, respectively. The Ki values obtained were 0.345 mM and 2.00 mM for the control group and 0.167mM and 0.325 mM for the hypertensive group, using ATP and ADP as substrate, respectively. In conclusion, based on these results it is possible to speculate that there is an interaction between vasodilators, donors of nitric oxide, and the inhibition of adenine nucleotide hydrolysis on platelets of hipertensive patients. / O processo trombogênico que afeta os pacientes hipertensos está associado com mecanismos regulatórios presentes no endotélio vascular. Esses mecanismos envolvem o fator de relaxamento do endotélio, as ectonucleotidases e íons cálcio. Considerando que os vasodilatadores atuam em ambos, na pressão sangüínea e na homeostase, foi avaliada a interferência de diferentes vasodilatadores na atividade da NTPDase de plaquetas de hipertensos e pacientes saudáveis, com o objetivo de verificar a sensibilidade destes pacientes aos vasodilatadores. Além disso, foi determinado o comportamento cinético da NTPDase na presença do vasodilatador que apresentou maior influência inibitória. Os resultados mostraram uma diminuição na atividade da NTPDase na presença de arginina (0,025 mM 3.0 mM), nitroprussiato de sódio (0,01 2,0 mM) e hidralazina (20,0 μM 90,0 μM), quando testada para os substratos ATP e ADP em plaquetas do grupo hipertensos. Porém, a hidrólise dos substratos ATP e ADP aumentou quando testado na presença de arginina no grupo controle. Nenhum efeito foi observado sobre a atividade da enzima quando doses farmacológicas de captopril foram testadas in vitro. Estudos do comportamento cinético foram realizados na presença de nitroprussiato de sódio, o qual causou uma inibição mista. Os valores de Km aumentaram e os de Vmax diminuíram com o aumento da concentração de nitroprussiato de sódio. Os valores de IC50 foram 3,66 mM e 2,64 mM (grupo controle) e 2,08 mM e 3,15 mM (grupo hipertenso) para ATP e ADP, respectivamente. Os valores de Ki obtidos foram 0,167 mM e 0,325 mM para o grupo hipertensos, usando ATP e ADP como substrato, respectivamente. Contudo, baseado nos resultados encontrados, é possível sugerir que existe uma interação entre vasodilatadores, doadores de óxido nítrico e a inibição da hidrólise de nucleotídeos da adenina em plaquetas de pacientes hipertensos.

O estudo de parâmetros cinéticos para a queima de carvão se dá através de utilização de equipamentos laboratoriais como o forno de queda livre (DTF). O presente trabalho trata do desenvolvimento e análise de um modelo numérico unidimensional de um DTF. A modelagem é realizada a partir de dados da literatura, e as equações discretizadas que caracterizam os fenômenos do escoamento, da transferência de calor e da combustão do carvão foram programadas na linguagem FORTRAN 90. Os resultados são comparados com um modelo de referência e com dados experimentais, e apresentaram boa concordância. Um estudo de sensibilidade é realizado para entender o comportamento da queima de carvão frente a mudanças de alguns parâmetros de operação do DTF. A análise de sensibilidade mostrou a versatilidade do modelo e, consequentemente, do experimento. A partir da variação da concentração de O2, da temperatura de operação e das vazões de entrada pode-se obter uma gama de resultados. O uso do modelo aqui apresentado concomitante com resultados experimentais resulta em um estudo aprofundado dos parâmetros cinéticos de combustão de carvão. / The study of kinetic parameters for coal combustion occurs through use of laboratory equipment such as drop tube furnace (DTF). The present work shows the development and analysis of a one-dimensional numerical model of a DTF. The modeling is developed from literature works, and the discrete equations that characterize the flow, heat transfer and coal combustion are programmed in FORTRAN 90 language. The results are compared with a reference model and experimental data, and showed good agreement. A sensitivity study is performed to understand the behavior of coal combustion due to changes of some working parameters of the DTF. The sensitivity analysis showed the versatility of the model and thereby the experiment. From the variation of the O2 concentration, operating temperature and input flow rates a range of results can be obtained. Using the model presented here together with experimental results leads to a detailed study of the kinetic parameters of coal combustion.

Os ésteres são importantes compostos orgânicos, obtidos por síntese química ou extraídos de alguns produtos naturais utilizando-se solvente em meio adequado. Estudos mostram que enzimas, em particular lipases, podem ser aplicadas na síntese de diversos ésteres. O principal objetivo deste trabalho foi a obtenção de acetato de butila, um éster de aroma característico de abacaxi, utilizando lipase de Geotrichum candidum produzida em fermentação submersa e imobilizada em matriz polimérica de alginato de bário e gelatina reticulada com glutaraldeído. A caracterização bioquímica foi realizada tanto para a lipase na forma livre como para a lipase na forma imobilizada. O rendimento em conversão molar de substrato foi determinado por cromatografia gasosa. A enzima apresentou atividade enzimática máxima após 48 horas de fermentação de 37,7 U/mL. Os valores ótimos para pH e temperatura da enzima na forma livre e imobilizada foram pH 6,5 e 40 °C e pH 7,5 e 45 °C, respectivamente. A enzima na forma livre foi estável do pH 6,0 ao 8,0 e à temperatura de 35 a 45 °C, já na forma imobilizada, foi estável do pH 5,5 ao 8,5 e na faixa de temperatura de 30 a 55 °C. A lipase imobilizada teve seus parâmetros cinéticos determinados, e os valores obtidos para o Km e Vmax, foram 0,115 mmol e 0,718 µmol.mL-1.min-1, respectivamente. As melhores condições de síntese do bioaroma para a enzima na forma livre foram: temperatura de 30 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 97,2 % de conversão molar em acetato de butila. Para a enzima imobilizada as melhores condições foram: temperatura de 45 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 99,1%, que demonstra que lipase produzida por Geotrichum candidum na forma imobilizada apresenta excelente capacidade de sintetizar acetato de butila (bioaroma de abacaxi). / Esters are important organic compounds obtained by chemical synthesis or derived from some natural products using a solvent in appropriate medium. Studies have shown that enzymes, particularly lipases, ca be applied in the synthesis of various esters. The main objective of this study was to obtain butyl acetate, a characteristic ester aroma of pineapple, using lipase from Geotrichum candidum produced in submerged fermentation and immobilized in a barium alginate and gelatin polymer matrix crosslinked with glutaraldehyde. The biochemical characterization was performed for both free and immobilized lipases. The yield in molar conversion of substrate was determined by gas chromatography. The enzyme showed maximum enzymatic activity after 48 hours of fermentation of 37.7 U/mL. The optimum values for pH and temperature of the enzyme in free and immobilize form were pH 6.5 and 40 °C and pH 7.5 and 45 °C, respectively. The enzyme was stable in free form from pH 6.0 to 8.0 and at temperatures from 35 to 45 °C, and in the immobilized form from pH 5.5 to 8.5 and at temperatures from 30 to 55 °C. Kinetic parameters of the immobilized lipase were determined, and the values obtained for Km and Vmax were 0.115 mmol and 0.718 µmol.mL-1.min-1, respectively. The best conditions for the synthesis of flavor by enzyme in free form were: 30 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 97.2% of molar conversion in butyl acetate. For the immobilized enzyme the best conditions were: 45 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 99.1%, demonstrating that lipase produced by Geotrichum candidum in immobilized form has an excellent ability to synthesize butyl acetate (pineapple flavor).

O estudo de parâmetros cinéticos para a queima de carvão se dá através de utilização de equipamentos laboratoriais como o forno de queda livre (DTF). O presente trabalho trata do desenvolvimento e análise de um modelo numérico unidimensional de um DTF. A modelagem é realizada a partir de dados da literatura, e as equações discretizadas que caracterizam os fenômenos do escoamento, da transferência de calor e da combustão do carvão foram programadas na linguagem FORTRAN 90. Os resultados são comparados com um modelo de referência e com dados experimentais, e apresentaram boa concordância. Um estudo de sensibilidade é realizado para entender o comportamento da queima de carvão frente a mudanças de alguns parâmetros de operação do DTF. A análise de sensibilidade mostrou a versatilidade do modelo e, consequentemente, do experimento. A partir da variação da concentração de O2, da temperatura de operação e das vazões de entrada pode-se obter uma gama de resultados. O uso do modelo aqui apresentado concomitante com resultados experimentais resulta em um estudo aprofundado dos parâmetros cinéticos de combustão de carvão. / The study of kinetic parameters for coal combustion occurs through use of laboratory equipment such as drop tube furnace (DTF). The present work shows the development and analysis of a one-dimensional numerical model of a DTF. The modeling is developed from literature works, and the discrete equations that characterize the flow, heat transfer and coal combustion are programmed in FORTRAN 90 language. The results are compared with a reference model and experimental data, and showed good agreement. A sensitivity study is performed to understand the behavior of coal combustion due to changes of some working parameters of the DTF. The sensitivity analysis showed the versatility of the model and thereby the experiment. From the variation of the O2 concentration, operating temperature and input flow rates a range of results can be obtained. Using the model presented here together with experimental results leads to a detailed study of the kinetic parameters of coal combustion.

A crescente necessidade de se obter fontes de energia e materiais mais sustentáveis tem aumentado o interesse em processos baseados na conversão de biomassa. Microalgas são particularmente interessantes por não competirem com alimentos e serem facilmente adaptáveis ao meio de crescimento. Além disso, microalgas podem ser processadas termicamente para geração tanto de biocombustíveis quanto de produtos químicos úteis. Estudos de conversão térmica de microalgas tem aparecido apenas em anos recentes, endereçando principalmente temperaturas entre 350 e 500 ºC. Neste estudo, a pirólise em temperaturas entre 500 e 900 ºC foi avaliada pelo interesse em se obter biocombustíveis e produtos químicos úteis. As classes de compostos obtidos a partir da pirólise isotérmica da microalga da espécie Chlorella vulgaris foram investigadas através de um sistema composto por um pirolisador conectado a um CG/MS. Dentre as classes identificadas, houve uma predominância de compostos aromáticos e nitrogenados, principalmente derivados de proteínas. Além disso, a maioria dos compostos identificados na corrente de produtos voláteis está presente em todas as temperaturas de reação estudadas. Os parâmetros cinéticos de energia de ativação aparente, constante de reação e ordem de reação foram determinados através de três modelos cinéticos conhecidos como K-A-S, Osawa e Freeman-Carroll, a partir de dados termogravimétricos. A energia de ativação determinada para Chlorella apresentou valores entre 60 e 206 kJ/mol, enquanto a ordem de reação teve como resultado valores entre segunda e décima ordem, de acordo com o modelo cinético. / The increasing need to obtain more sustainable sources of energy and raw materials has attracted attention to processes based on biomass conversion. Microalgae are particularly interesting because they do not compete with human food and they are easily adaptable to the growth medium. Besides, microalgae can be thermally processed to produce both biofuels and useful chemicals. Studies on thermal conversion of microalgae have appeared only in recent years, addressing mainly reaction temperatures between 350 and 500 °C. In this study, pyrolysis in temperatures ranging from 500 to 900 ºC have been investigated considering the interest in producing biofuels and useful chemical compounds. The classes of products obtained by isothermal pyrolysis of the Chlorella vulgaris microalgae have been investigated using a pyrolyzer directly connected to a GC/MS system. Among the classes identified, there was a predominance of aromatic and nitrogenous compounds, mainly protein derived compounds. In addition, most products identified in the volatile products stream are present in all reaction temperatures investigated. The kinetic parameters of apparent activation energy, reaction constant and order of reaction were determined through three kinetic models known as K-A-S, Osawa and Freeman-Carroll, calculated from thermogravimetric data. The activation energy for Chlorella presented values within the range of 60 and 206 kJ/mole, while the order of reaction resulted in values between second and tenth order, from the different methods.

In the post-genomic era, there is a dire need for tools to perform metabolic analyses that include the structural, functional, and regulatory analysis of metabolic networks. This need arose because of the lag between the two phases of metabolic engineering, namely, synthesis and analysis. Molecular biological tools for synthesis like recombinant DNA technology and genetic engineering have advanced a lot farther than tools for systemic analysis. Consequently, bioinformatics is poised to play an important role in bridging the gap between the two phases of metabolic engineering, thereby accelerating the improvement of organisms by using predictive simulations that can be done in minutes rather than mutant constructions that require weeks to months. In addition, metabolism occurs at a rapid speed compared to other cellular activities and has two states, dynamic state and steady state. Dynamic state analysis sheds more light on the mechanisms and regulation of metabolism than its steady state counterpart. Currently, several in silico tools exist for steady-state analysis of metabolism, but tools for dynamic analysis are lacking. This research focused on simulating the dynamic state of metabolism for predictive analysis of the metabolic changes in an organism during metabolic engineering. The goals of this research were accomplished by developing two software tools. Metabolome Searcher, a web-based high throughput tool, facilitates putative compound identification and metabolic pathway mapping of mass spectrometry data by applying genome-restriction. The second tool, DynaFlux, uses these compound identifications along with time course data obtained from a mass spectrometer in conjunction with the pathways of interest to simulate and estimate dynamic-state metabolic flux, as well as to analyze the network properties. The features available in DynaFlux are: 1) derivation of the metabolic reconstructions from Pathway Tools software for the simulation; 2) automated building of the mathematical model of the metabolic network; 3) estimation of the kinetic parameters, KR, v, Vmaxf, Vmaxr, and Kdy, using hybrid-mutation random-restart hill climbing search; 4) perturbation studies of enzyme activities; 5) enumeration of feasible routes between two metabolites; 6) determination of the minimal enzyme set and dispensable enzyme set; 7) imputation of missing metabolite data; and 8) visualization of the network.

No description available.