Convection in the Earth's mantle is a complicated phenomenon that causes various tectonic activities and affects mantle evolution on geologic time scales (billions of years). It is a subject as yet not fully understood. The early success of the high Rayleigh number constant viscosity theory was later tempered by the absence of plate motion when the viscosity is more realistically strongly temperature dependent. A similar problem arises if the equally strong pressure dependence of viscosity is considered, since the classical isothermal core convection theory would then imply a strongly variable mantle viscosity, which is inconsistent with results from postglacial rebound studies. We consider a mathematical model for Rayleigh-Bénard convection in a basally heated layer of a fluid whose viscosity depends strongly on both temperature and pressure, defined in an Arrhenius form. The model is solved numerically for extremely large viscosity variations across a unit aspect ratio cell, and steady solutions are obtained. To improve the efficiency of numerical computation, we introduce a modified viscosity law with a low temperature cut-off. We demonstrate that this simplification results in markedly improved numerical convergence without compromising accuracy. Continued numerical experiments suggest that narrow cells are preferred at extreme viscosity contrasts. We are then able to determine the asymptotic structure of the solution, and it agrees well with the numerical results. Beneath a stagnant lid, there is a vigorous convection in the upper part of the cell, and a more sluggish, higher viscosity flow in the lower part of the cell. We then offer some comments on the meaning and interpretation of these results for planetary mantle convection.

Introdução: Doze a 29 % dos ejaculados tem viscosidade seminal aumentada. Uma das técnicas recomendadas para diminuir a viscosidade do sêmen consiste num processo físico em que se passa o sêmen, 4 vezes, por uma seringa de 10 mL com agulha 18G. Ao fim desse processo, ter-se-ia modificado o comportamento molecular das fibrilas protéicas do esperma, tornando-o mais liquefeito, sem dano aparente a morfologia ou motilidade dos espermatozoides. Atualmente, discute-se sobre a total inocuidade desta técnica, uma vez que ela poderia provocar aumento da fragmentação do DNA dos espermatozoides. A hiperviscosidade seminal, além de reduzir a concentração e a motilidade dos espermatozoides, pode afetar a capacitação e a reação acrossômica, podendo ter implicações na integridade do DNA e no desenvolvimento embrionário normal. Objetivo: Comparar a fragmentação do DNA de espermatozoides humanos em amostras com viscosidade diminuída, fisiológica e aumentada, e avaliar se o processo de expulsão do sêmen através da agulha e seringa altera significativamente as taxas de fragmentação do DNA dos espermatozoides. Método: Após a coleta e avaliação dos parâmetros seminais das amostras de sêmen, aquelas que estiverem com viscosidade aumentada passarão pelo processo de expulsão através da seringa de 10 mL com agulha 18G por 4 vezes, para diminuir a viscosidade seminal. Posteriormente, serão feitas análises da fragmentação do DNA dos espermatozoides através da técnica de TUNEL em todas as amostras. Resultados: A fragmentação do DNA entre amostras com viscosidade fisiológica, diminuída e aumentada não apresentou diferença estatisticamente significativa (P=0,857). A fragmentação do DNA aumentou significativamente (P=0,035) nas amostras com viscosidade aumentada após passar na seringa e agulha quando comparadas com as mesmas amostras antes de passar pela mesma. Conclusão: O processo de expulsão do sêmen através de seringa e agulha visando redução da viscosidade seminal aumenta a fragmentação do DNA no espermatozoide, devendo este processo ser substituído por um processo inócuo. / Background: Twelve to 29 % of the ejaculated have the semen viscosity increased. One of the techniques recommended to decrease the viscosity of semen is a physical process in which the semen passes four times through a 10mL syringe with a 18G needle. At the end of this process would have modified the molecular behavior of the protein fibrils of the sperm making it more liquefied, without apparent damage to the morphology or motility of spermatozoa. Currently, the debate is about the complete safety of this technique since it could result in increased DNA fragmentation of spermatozoa. The seminal viscosity moreover reduces the concentration and motility of sperm, can affect the capacitation and acrosome reaction which may have implications for DNA integrity and normal embryonic development. Objective: To compare the DNA fragmentation in human semen samples with reduced, physiological and increased viscosity and evaluate if the process of expulsion of semen through the needle and syringe significantly alter rates of sperm DNA fragmentation. Methods: After collecting and evaluating semen parameters of semen samples, those that are with increased viscosity will pass through the process of expulsion through the 10 mL syringe with a 18G needle four times to reduce the viscosity of semen. After that, analysis of spermatozoa DNA fragmentation through the TUNEL technique will be made in all samples. Results: The fragmentation of DNA between samples with physiological, reduced and increased viscosity is not statistically significant (P=0.857). The DNA fragmentation increased significantly (P=0.035) in samples with increased viscosity after passing the syringe and needle when compared with the same samples before going through the same. Conclusion: The process of expulsion of semen through a syringe and needle in order to reduce the semen viscosity increases the DNA fragmentation in sperm, and this shall be replaced by a harmless process.

Part 1 The viscosity of silicate melts is a fundamental physical property that determines the mobility and transport behaviour of magma on the surface and in planetary interiors. The viscosity of liquid fayalite (Fe2SiO4), the Fe-rich end-member of the abundant upper mantle mineral olivine, was determined up to 9.2 GPa and 1850 °C using in situ falling sphere viscometry and X-ray radiography imaging. The viscosity of liquid fayalite was found to decrease with pressure both along the melting curve and an isotherm, with temperature having very little influence on viscosity at high pressure. This work is the first to determine the viscosity of a highly depolymerized silicate melt at high pressure as only recent advances in experimental techniques have allowed the difficulties associated with studying depolymerized liquids at high pressure to be overcome. The results are in contrast with previous studies on moderately depolymerized silicate melts such as diopside and peridotite which found viscosity to initially increase with pressure. In accordance with recent in situ structural measurements on liquid fayalite, the viscosity decrease is likely a result of the increase in Fe-O coordination with pressure. The results show that the behaviour of silicate melts at depth is strongly dependent on the melt structure and composition. Part 2 The magnitude of the thermal anomaly at hotspot locations has a fundamental influence on the dynamics of mantle melting and therefore has an important role in shaping the surface of our planet. The North Atlantic Igneous Province (NAIP) is the surface expression of a major mantle plume and is unique in the fact that it has a complete magmatic history. The highest 3He/4He volcanic rocks on Earth are found in the early NAIP picrites of West Greenland and Bafin Island and high 3He/4He rocks are still erupted on Iceland today. However, the relationship between 3He/4He and mantle plumes has remained enigmatic. The main aim of this work is to use the ideal opportunity provided by the NAIP to investigate the relationship between temperature, mantle melting dynamics and helium isotopes within a mantle plume. The magmatic temperatures of a suite of picrites and primitive basalts spanning the spatial and temporal range of the NAIP was determined using traditional olivine-melt thermometry, a forward mantle melting model and the newly developed Al-in-olivine thermometer. This study is the first to provide a detailed petrologic approach to investigating the mantle temperature of the NAIP throughout its magmatic history and is the first to compare all three techniques in detail. The Al-in-olivine thermometer was found to be the most robust proxy for mantle temperature. The early stage of volcanic activity in the NAIP is associated with the arrival of the ancestral Iceland plume head and resulted in a uniform temperature anomaly with Al-in-olivine temperatures 250-300° above that of ambient MORB across an area 2000 km in diameter. In addition, the temperature of the plume is shown to have been subject to large temperature fluctuations on a timescale of 107 years and is currently increasing, which has had profound effects on the melting dynamics and bathymetry of the North Atlantic region. Using existing and new 3He/4He measurements, no clear relationship between 3He/4He and temperature is observable. However, it is noted that the maximum 3He/4He of primitive basalts from the NAIP has decreased through time. These relationships are explicable if the high 3He/4He reservoir is located in either the core or the core-mantle boundary (CMB), from which helium diffuses into the lower mantle. The high 3He=4He signature is incorporated into a plume when it breaks away from the base of the mantle and over the lifetime of the plume, the 3He/4He source is gradually depleted. The temperature of the plume can vary independently in responses to heat flow at the CMB, which is in turn related to changes in mantle convection. Global plate tectonics and mantle processes are therefore intricately linked with melting dynamics at hotspot locations.

Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-15Bitstream added on 2014-06-13T19:31:45Z : No. of bitstreams: 1 souza_ac_me_sjrp.pdf: 887036 bytes, checksum: f8baf654f6ac3238cb12ab9fdef0e338 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O comportamento reológico de suspensões de cristais de sacarose em soluções aquosas saturadas de sacarose foi avaliado usando um reômetro acoplado a um agitador, mais conhecido como reômetro de turbina. Foram analisadas suspensões formadas por soluções aquosas saturadas de sacarose a diferentes temperaturas (e, portanto, com diferentes concentrações de sacarose), às quais foram adicionadas diferentes frações de cristais de sacarose de tamanho conhecido. As frações de cristais de sacarose usadas na composição das suspensões foram separadas, através de peneiramento, a partir de três diferentes tipos de açúcares comerciais: açúcar granulado, refinado e de confeiteiro. As soluções aquosas saturadas de sacarose, consideradas como meio dispersante das suspensões, foram caracterizadas reologicamente utilizando-se um reômetro rotacional de cilindros concêntricos. Todas as soluções analisadas apresentaram comportamento Newtoniano nas faixas de concentração e temperatura avaliadas. Já as suspensões de cristais de sacarose em soluções aquosas saturadas de sacarose foram avaliadas reologicamente com o auxílio do reômetro de turbina, o qual foi montado na base do reômetro rotacional de cilindros concêntricos e cujo agitador foi acoplado ao eixo originalmente destinado ao cilindro interno. O agitador usado no equipamento foi do tipo âncora e teve suas constantes determinadas através de metodologia específica. As suspensões analisadas também apresentaram comportamento reológico do tipo Newtoniano. Os resultados obtidos foram utilizados para a obtenção de modelos relacionando a viscosidade das suspensões à fração das partículas cristalinas presentes no sistema, bem como às características reológicas do meio líquido. / Rheological properties of suspensions of sucrose crystals in saturated sucrose aqueous solutions were investigated using a rheometer coupled to an agitator, also known as mixer-type rheometer. Suspensions formed by saturated solutions were analyzed at different temperatures (and, therefore, at different sucrose concentrations), and with different added fractions of sucrose crystals of known size. Three different types of commercial sugars (granulated, refined, and confectioner) were sieved in order to obtain fractions of sucrose crystals of different sizes. Saturated sucrose aqueous solutions, considered as a suspension dispersant mean, were rheologically characterized using a concentric cylinders rheometer. In the studied ranges of concentration and temperature, all analyzed solutions showed Newtonian behavior. The crystals suspensions in saturated sucrose aqueous solutions were rheologically evaluated by using the mixer-type rheometer, which was coupled to the concentric cylinders rheometer. The impeller was an anchor type agitator and had their constants determined by means of a specific methodology. The analyzed suspensions also showed Newtonian behavior. The experimental results were used to obtain mathematical models relating the suspensions viscosity to the dispersant liquid phase viscosity and to the volumetric fraction of crystals.

Made available in DSpace on 2014-10-09T12:53:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:48Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:40:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:11Z (GMT). No. of bitstreams: 1 02951.pdf: 3722798 bytes, checksum: 4c42b3ba1eb1c51f8f47bb210f5763f4 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:41:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:42Z (GMT). No. of bitstreams: 1 04028.pdf: 4334494 bytes, checksum: 3b9778498dc6bdac0e8a5c8f8ad038da (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Efetuou-se, de forma inédita, a avaliação da viscosidade de dois óleos Newtonianos em velocidades distintas de escoamento (1000rpm e 1500rpm) e em função da temperatura (24ºC a 50ºC), através de um método de reologia a laser, que consiste num interferômetro óptico acoplado a um spinner. Para a obtenção dos dados experimentais desenvolveu-se um sistema de aquecimento, o qual foi acoplado ao spinner, garantindo assim a estabilidade térmica durante o processo. Os dados experimentais obtidos através do método de reologia a laser corroboraram com o modelo de Emslie, Bonner e Peck (EBP), considerando que o modelo do coeficiente de determinação múltipla (R²) para o ajuste linear dos dados manteve-se muito próximo a 1. Já em comparação com o método tradicional, que utiliza a imersão de um spindle dentro de um Becker com fluído, e, dentro das incertezas experimentais, obteve-se boa concordância dos dados. Além disso, encontrou-se boa concordância com o modelo de Arrhenius que descreve o comportamento da viscosidade de fluídos em função da temperatura. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-05-11T18:45:09Z No. of bitstreams: 1 Dissertacao Leticia Reinheimer.pdf: 7991063 bytes, checksum: 0c9c7a9c3f121a460c217d4225c87ef1 (MD5) / Made available in DSpace on 2015-05-11T18:45:09Z (GMT). No. of bitstreams: 1 Dissertacao Leticia Reinheimer.pdf: 7991063 bytes, checksum: 0c9c7a9c3f121a460c217d4225c87ef1 (MD5) / The viscosity assessment of two Newtonian oil was done in an unprecedented way in different flow speeds (1000rpm e 1500rpm), and as temperature function (24ºC to 50ºC), through a laser rheology method, which consists of an optical interferometer coupled to a spinner. To obtain the experimental data, a heatingsystem was developed, which was coupled to the spinner, thus ensuring the thermal stability during the process. The experimental data obtained through rheology laser method corroborated with the Emslie, Bonner e Parker (EBP) model, in which the coefficient of multiple determination, R² for a linear adjustment was close to 1. Therefore, in comparison to the traditional method and within the experimental uncertainty great data concordance was obtained. Also, great data concordance was found with the Arrhenius model, which describes the behavior of fluids viscosity due to the temperature.

A qualidade dos combustíveis é um dos principais fatores que afetam o desempenho dos motores de combustão interna e é caracterizada por um conjunto de propriedades físicas e químicas. Neste trabalho foi investigada a influência da temperatura sobre algumas propriedades como a densidade, viscosidade dinâmica, ponto de névoa e de fluidez de diferentes combustíveis. Além disso, medidas envolvendo termogravimetria e espectrometria na região do infravermelho médio também foram conduzidas. Medidas de densidade em função da temperatura ou da concentração de biodiesel na amostra revelaram uma dependência linear, de forma que a redução da temperatura ou o aumento da concentração de biodiesel provocaram um aumento da densidade. O estudo reológico a partir de medidas de viscosidade permitiu identificar o comportamento de fluido Newtoniano para todas as amostras analisadas. Um ajuste exponencial do tipo Arrhenius foi utilizado para analisar a correlação entre viscosidade dinâmica e temperatura, possibilitando identificar uma temperatura limite, T*, abaixo da qual esse ajuste não é mais satisfeito e o processo de solidificação da amostra é desencadeado. Um diagrama de fases em função das temperaturas T*, do ponto de névoa e de fluidez foi elaborado, possibilitando identificar, em função da concentração de biodiesel da amostra, faixas de temperaturas onde as fases líquidas e/ou sólidas podem ser encontradas, bem como onde o ajuste entre a viscosidade dinâmica e a temperatura pode ser obtido por uma equação exponencial do tipo Arrhenius. Além disso, medidas calorimétricas revelaram uma maior energia por unidade de massa para as amostras de diesel padrão, e que esta energia decresce linearmente com o incremento da concentração de biodiesel na amostra. Termogramas revelaram diferentes perfis de degradação térmica para as amostras, de forma que um deslocamento da curva de degradação para temperaturas mais elevadas foi observado em função do aumento do teor de enxofre nas amostras de diesel padrão assim como pelo incremento da concentração de biodiesel nas amostras produzidas pela mistura entre diesel e biodiesel. A análise das amostras líquidas utilizando radiação com comprimento de ondas no infravermelho permitiram identificar diferentes grupos funcionais presentes nas amostras e estabelecer, em termos da intensidade da absorbância característica da dupla ligação Carbono-Oxigênio presentes nos ésteres do biodiesel, uma relação com a concentração de biodiesel presente na amostra. Neste sentido, por meio da análise de diferentes propriedades físicas e químicas das amostras estudadas, foi possível avaliar características e interdependências destas propriedades, principalmente no que diz respeito a variações da temperatura. Sendo assim, ao longo deste trabalho, são apresentados dados e apontamentos importantes para tratar do tema abordado. / Fuel quality is a major factor affecting the performance of internal combustion engines and it is characterized by a combination of physical and chemical properties. In this study, the influence of temperature on some properties such as density, dynamic viscosity, cloud point and pour point were investigated in different samples of fuels. In addition, measurements involving thermogravimetry and infrared spectroscopy were also performed. Density measurements as a function of temperature or concentration of biodiesel in the sample revealed a linear dependence, indicating that the temperature reduction or increase of the concentration of biodiesel results in a density increase. The rheological study from dynamic viscosity measurements identified the Newtonian fluid behavior for all samples. It was also observed an increase in the dynamic viscosity caused by the increase of the concentration of biodiesel in the sample and also the reducing the temperature. An exponential fit of the Arrhenius type equation was used to analyze the correlation between dynamic viscosity and temperature, allowing to identify a temperature limit, T*, below which this adjustment is lost and the sample solidification process is triggered. A phase diagram as a function of the biodiesel concentration and the temperature T*, the cloud point and poor point was prepared. This diagram shows the temperature ranges in which liquid and/or solid phases can be found, and where the fit between the temperature and dynamic viscosity can be obtained by an exponential equation of Arrhenius type. In addition, calorimetric measurements revealed a higher energy per mass unit for the standard diesel samples, and that this energy decreases linearly with increasing of biodiesel content. Thermal analysis showed different degradation profiles for the samples. Thermograms indicated a shift of the degradation curve at higher temperatures due to the increase in the sulfur content in the samples of standard diesel and also increasing the biodiesel concentration in the samples produced by mixture of diesel and biodiesel. The analysis of liquid samples using infrared radiation allowed the identification of different functional groups present in the samples and to establish, in terms of the intensity of the absorbance characteristic of the carbon-oxygen double bond present in the esters of biodiesel, a relation with the concentration of biodiesel present in the sample. In this sense, through the analysis of different physical and chemical properties of the samples, it was possible to evaluate characteristics and interrelationships of these properties, particularly in respect of temperature variations, which can favor or disfavor the increased biodiesel concentration in blends with diesel. Thus, throughout this study are presented important data and notes related with the theme.

A qualidade dos combustíveis é um dos principais fatores que afetam o desempenho dos motores de combustão interna e é caracterizada por um conjunto de propriedades físicas e químicas. Neste trabalho foi investigada a influência da temperatura sobre algumas propriedades como a densidade, viscosidade dinâmica, ponto de névoa e de fluidez de diferentes combustíveis. Além disso, medidas envolvendo termogravimetria e espectrometria na região do infravermelho médio também foram conduzidas. Medidas de densidade em função da temperatura ou da concentração de biodiesel na amostra revelaram uma dependência linear, de forma que a redução da temperatura ou o aumento da concentração de biodiesel provocaram um aumento da densidade. O estudo reológico a partir de medidas de viscosidade permitiu identificar o comportamento de fluido Newtoniano para todas as amostras analisadas. Um ajuste exponencial do tipo Arrhenius foi utilizado para analisar a correlação entre viscosidade dinâmica e temperatura, possibilitando identificar uma temperatura limite, T*, abaixo da qual esse ajuste não é mais satisfeito e o processo de solidificação da amostra é desencadeado. Um diagrama de fases em função das temperaturas T*, do ponto de névoa e de fluidez foi elaborado, possibilitando identificar, em função da concentração de biodiesel da amostra, faixas de temperaturas onde as fases líquidas e/ou sólidas podem ser encontradas, bem como onde o ajuste entre a viscosidade dinâmica e a temperatura pode ser obtido por uma equação exponencial do tipo Arrhenius. Além disso, medidas calorimétricas revelaram uma maior energia por unidade de massa para as amostras de diesel padrão, e que esta energia decresce linearmente com o incremento da concentração de biodiesel na amostra. Termogramas revelaram diferentes perfis de degradação térmica para as amostras, de forma que um deslocamento da curva de degradação para temperaturas mais elevadas foi observado em função do aumento do teor de enxofre nas amostras de diesel padrão assim como pelo incremento da concentração de biodiesel nas amostras produzidas pela mistura entre diesel e biodiesel. A análise das amostras líquidas utilizando radiação com comprimento de ondas no infravermelho permitiram identificar diferentes grupos funcionais presentes nas amostras e estabelecer, em termos da intensidade da absorbância característica da dupla ligação Carbono-Oxigênio presentes nos ésteres do biodiesel, uma relação com a concentração de biodiesel presente na amostra. Neste sentido, por meio da análise de diferentes propriedades físicas e químicas das amostras estudadas, foi possível avaliar características e interdependências destas propriedades, principalmente no que diz respeito a variações da temperatura. Sendo assim, ao longo deste trabalho, são apresentados dados e apontamentos importantes para tratar do tema abordado. / Fuel quality is a major factor affecting the performance of internal combustion engines and it is characterized by a combination of physical and chemical properties. In this study, the influence of temperature on some properties such as density, dynamic viscosity, cloud point and pour point were investigated in different samples of fuels. In addition, measurements involving thermogravimetry and infrared spectroscopy were also performed. Density measurements as a function of temperature or concentration of biodiesel in the sample revealed a linear dependence, indicating that the temperature reduction or increase of the concentration of biodiesel results in a density increase. The rheological study from dynamic viscosity measurements identified the Newtonian fluid behavior for all samples. It was also observed an increase in the dynamic viscosity caused by the increase of the concentration of biodiesel in the sample and also the reducing the temperature. An exponential fit of the Arrhenius type equation was used to analyze the correlation between dynamic viscosity and temperature, allowing to identify a temperature limit, T*, below which this adjustment is lost and the sample solidification process is triggered. A phase diagram as a function of the biodiesel concentration and the temperature T*, the cloud point and poor point was prepared. This diagram shows the temperature ranges in which liquid and/or solid phases can be found, and where the fit between the temperature and dynamic viscosity can be obtained by an exponential equation of Arrhenius type. In addition, calorimetric measurements revealed a higher energy per mass unit for the standard diesel samples, and that this energy decreases linearly with increasing of biodiesel content. Thermal analysis showed different degradation profiles for the samples. Thermograms indicated a shift of the degradation curve at higher temperatures due to the increase in the sulfur content in the samples of standard diesel and also increasing the biodiesel concentration in the samples produced by mixture of diesel and biodiesel. The analysis of liquid samples using infrared radiation allowed the identification of different functional groups present in the samples and to establish, in terms of the intensity of the absorbance characteristic of the carbon-oxygen double bond present in the esters of biodiesel, a relation with the concentration of biodiesel present in the sample. In this sense, through the analysis of different physical and chemical properties of the samples, it was possible to evaluate characteristics and interrelationships of these properties, particularly in respect of temperature variations, which can favor or disfavor the increased biodiesel concentration in blends with diesel. Thus, throughout this study are presented important data and notes related with the theme.