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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caracterização do PolyParaPhenylene (PPP) dopado com FeCl3, utilizando espectroscopia de alta resolução por ressonância magnética nuclear / Characterization of FeCl3-doped PolyParaPhenylene (PPP) using high resolution nuclear magnetic resonance spectroscopy

Giotto, Marcus Vinicius 19 April 1993 (has links)
O objetivo deste trabalho consiste na caracterização do polímero PolyParaPhenylene (PPP) dopado com FeCl3, usando a técnica de Espectroscopia de Alta Resolução em Sólidos por Ressonância Magnética Nuclear. Os espectros de alta resolução de 13C foram obtidos usando, simultaneamente, as técnicas de desacoplamento em alta potencia (DEC) e rotação da amostra em torno do angulo mágico (MASS). Alterações nos espectros de 13C do PPP dopado com FeCl3 causadas por defeitos na cadeia polimérica, tal como polarons e bipolarons, foram analisadas. Efeitos de variação de temperatura e purificação sobre os espectros do PPP, também foram estudados. As amostras foram, adicionalmente, caracterizadas por outras técnicas espectroscópicas, tal como Ressonância Paramagnética Eletrônica (EPR), Efeito Mossbauer, Infra Vermelho e Absorção Atômica; bem como por medidas de Condutividade. Nos observamos que as alterações nas larguras de linha de RMN, estão relacionadas com o aparecimento de bipolarons na cadeia polimérica. / The objective of this work consist of the characterization of FeCl3 doped PolyParaPhenylene (PPP) polymer, using Solid State High Resolution Nuclear Magnetic Resonance Spectroscopy. The 13C high resolution spectra were obtained simultaneously using High Power Decoupling (DEC) and Magic Angle Sample Spinning (MASS) techniques. Alterations in the high resolution 13C spectra of FeCl3 doped PPP caused by defects in the polymer chain such as polarons and bipolarons were analyzed. Effect of temperature variation and purification upon the PPP spectra was also studied. The samples were additionally characterized by others spectroscopic techniques such as Electron Paramagnetic Resonance (EPR), Mossbauer Effect, Infrared and Atomic Absorption as well as by conductivity measurements. We observed that the NMR linewidth changes are related to appearance of the bipolaron in the polymeric chain
2

Caracterização do PolyParaPhenylene (PPP) dopado com FeCl3, utilizando espectroscopia de alta resolução por ressonância magnética nuclear / Characterization of FeCl3-doped PolyParaPhenylene (PPP) using high resolution nuclear magnetic resonance spectroscopy

Marcus Vinicius Giotto 19 April 1993 (has links)
O objetivo deste trabalho consiste na caracterização do polímero PolyParaPhenylene (PPP) dopado com FeCl3, usando a técnica de Espectroscopia de Alta Resolução em Sólidos por Ressonância Magnética Nuclear. Os espectros de alta resolução de 13C foram obtidos usando, simultaneamente, as técnicas de desacoplamento em alta potencia (DEC) e rotação da amostra em torno do angulo mágico (MASS). Alterações nos espectros de 13C do PPP dopado com FeCl3 causadas por defeitos na cadeia polimérica, tal como polarons e bipolarons, foram analisadas. Efeitos de variação de temperatura e purificação sobre os espectros do PPP, também foram estudados. As amostras foram, adicionalmente, caracterizadas por outras técnicas espectroscópicas, tal como Ressonância Paramagnética Eletrônica (EPR), Efeito Mossbauer, Infra Vermelho e Absorção Atômica; bem como por medidas de Condutividade. Nos observamos que as alterações nas larguras de linha de RMN, estão relacionadas com o aparecimento de bipolarons na cadeia polimérica. / The objective of this work consist of the characterization of FeCl3 doped PolyParaPhenylene (PPP) polymer, using Solid State High Resolution Nuclear Magnetic Resonance Spectroscopy. The 13C high resolution spectra were obtained simultaneously using High Power Decoupling (DEC) and Magic Angle Sample Spinning (MASS) techniques. Alterations in the high resolution 13C spectra of FeCl3 doped PPP caused by defects in the polymer chain such as polarons and bipolarons were analyzed. Effect of temperature variation and purification upon the PPP spectra was also studied. The samples were additionally characterized by others spectroscopic techniques such as Electron Paramagnetic Resonance (EPR), Mossbauer Effect, Infrared and Atomic Absorption as well as by conductivity measurements. We observed that the NMR linewidth changes are related to appearance of the bipolaron in the polymeric chain
3

Korozní odolnost litých duplexních ocelí / Corrosion resistance of cast duplex stainless steels

Müller, Peter January 2020 (has links)
The master’s thesis deals with corrosion resistance of cast duplex steels. In the first part the corrosion mechanisms and their individual types are described, the second part characterizes the types of stainless steels in terms of their properties, use, structural components, and their impact on mechanical and corrosion properties of steels. Individual chapter is dedicated to duplex steels. In the experimental part the resistance of 1.4517 steel against pitting corrosion depending on the alloy contents and the PREN value was investigated. Four specimens graded according to PREN were cast. Supplemented with sample stirrer blade which was affected by corrosion during service they were subjected to corrosion test according to ASTM G48-11 standard in 6% FeCl3 solution. Cast specimens were subjected to tensile test and impact test.
4

Avaliação de reator UASB assistido quimicamente para remoção de fósforo / UASB reactor chemically assisted evaluation for phosphorus removal.

Queiroz, Ruy Scanho Marques de 17 May 2007 (has links)
Este trabalho visou avaliar a remoção de fósforo solúvel e total, carga orgânica, sulfetos e sólidos num esgoto doméstico fraco, ao qual se adicionou como coagulante o cloreto férrico, atravessando o manto de lodo de um tratamento anaeróbio UASB. A ETE Ribeirão Pires, aonde este estudo foi desenvolvido, conta com 4 reatores com capacidade para tratar 70 L/s, dos quais 2 foram utilizados, num deles (reator B) foram dosados 25 e 50 mg FeCl3/L e no outro (reator C) não houve dosagem, servindo como referência. Em cada uma das fases, foram realizadas 20 amostragens para DQO, fósforo total e solúvel, alcalinidade, pH e sólidos suspensos. Para DBO5,20ºC, sulfetos, sólidos totais e sedimentáveis foram obtidos 10 valores em cada dosagem. Os pontos de coleta foram: esgoto bruto e esgoto tratado dos reatores B e C. Foram coletadas amostras em 3 alturas do manto de lodo e realizadas as séries de sólidos em cada dosagem. Quanto à secagem desse lodo, os itens ciclo de desaguamento, espessura da camada e teor de sólidos foram comparados em descartes aos leitos de secagem da ETE. Da avaliação, pode-se concluir que a adição de cloreto férrico gera aumento considerável de remoção de carga orgânica (de 55% para 73% da DQO e de 63% para 82% da DBO5,20ºC, com 50 mg FeCl3/L). Quanto ao fósforo, as eficiências foram menores, sendo mais notadas nos ortofosfatos (de 28% para 36% de fósforo total e de 0% para 59% de solúvel com 50 mg FeCl3/L). Com relação ao lodo gerado, houve diminuição do ciclo de secagem e do volume da torta (do lodo com adição) em relação àquela gerada no reator sem adição de cloreto férrico. O manto de lodo se mostrou mais espesso e com menor concentração de sólidos no reator com aplicação de cloreto férrico, sugerindo uma tendência a maior perda de sólidos com o efluente clarificado. / The presented work intended to evaluate the removal of soluble and total phosphorus, organic matter (BOD5,20ºC and COD), sulfides and solids in a weak domestic wastewater, to which it was added ferric chloride as precipitant, crossing an UASB sludge blanket. The Ribeirão Pires wastewater treatment plant, where this study took place, is composed by 4 UASB reactors. In one of them (reactor B), 25 and 50 mg FeCl3/L were dosed, and in another (reactor C) there were no dosage, serving as a reference. In each of the stages, it had been carried through around 20 samplings for COD, total and soluble phosphorus, alkalinity, pH and suspended solids. For BOD5,20ºC, total sulfides, total solids and settleable solids it had been gotten 10 values in each dosage. The collection points had been: raw wastewater and treated wastewater from reactors B and C. Samples in 3 heights of the sludge blanket had been collected and carried through the solid series analysis in each dosage. About the sludge dewatering, items as dewatering period, layer thickness and total solids had been compared in some discharges to the drying beds. From this evaluation, it can be concluded that the ferric chloride addition generates an increase of organic matter removal (from 55% to 73% of the COD and from 63% to 82% of the BOD5,20ºC, with 50 mg FeCl3/L). For phosphorus, the removal efficiencies had been lower, more noticed in the soluble portion (from 28% to 36% of total and from 0% to 59% of soluble phosphorus at 50 mg FeCl3/L). Improvement in the dewatering capacity and in sludge cake volume were also noticed. The sludge blanket showed thicker and with a lower solid concentration in the reactor with ferric chloride application, suggesting a trend to solids loss in the clarified effluent.
5

Avaliação de reator UASB assistido quimicamente para remoção de fósforo / UASB reactor chemically assisted evaluation for phosphorus removal.

Ruy Scanho Marques de Queiroz 17 May 2007 (has links)
Este trabalho visou avaliar a remoção de fósforo solúvel e total, carga orgânica, sulfetos e sólidos num esgoto doméstico fraco, ao qual se adicionou como coagulante o cloreto férrico, atravessando o manto de lodo de um tratamento anaeróbio UASB. A ETE Ribeirão Pires, aonde este estudo foi desenvolvido, conta com 4 reatores com capacidade para tratar 70 L/s, dos quais 2 foram utilizados, num deles (reator B) foram dosados 25 e 50 mg FeCl3/L e no outro (reator C) não houve dosagem, servindo como referência. Em cada uma das fases, foram realizadas 20 amostragens para DQO, fósforo total e solúvel, alcalinidade, pH e sólidos suspensos. Para DBO5,20ºC, sulfetos, sólidos totais e sedimentáveis foram obtidos 10 valores em cada dosagem. Os pontos de coleta foram: esgoto bruto e esgoto tratado dos reatores B e C. Foram coletadas amostras em 3 alturas do manto de lodo e realizadas as séries de sólidos em cada dosagem. Quanto à secagem desse lodo, os itens ciclo de desaguamento, espessura da camada e teor de sólidos foram comparados em descartes aos leitos de secagem da ETE. Da avaliação, pode-se concluir que a adição de cloreto férrico gera aumento considerável de remoção de carga orgânica (de 55% para 73% da DQO e de 63% para 82% da DBO5,20ºC, com 50 mg FeCl3/L). Quanto ao fósforo, as eficiências foram menores, sendo mais notadas nos ortofosfatos (de 28% para 36% de fósforo total e de 0% para 59% de solúvel com 50 mg FeCl3/L). Com relação ao lodo gerado, houve diminuição do ciclo de secagem e do volume da torta (do lodo com adição) em relação àquela gerada no reator sem adição de cloreto férrico. O manto de lodo se mostrou mais espesso e com menor concentração de sólidos no reator com aplicação de cloreto férrico, sugerindo uma tendência a maior perda de sólidos com o efluente clarificado. / The presented work intended to evaluate the removal of soluble and total phosphorus, organic matter (BOD5,20ºC and COD), sulfides and solids in a weak domestic wastewater, to which it was added ferric chloride as precipitant, crossing an UASB sludge blanket. The Ribeirão Pires wastewater treatment plant, where this study took place, is composed by 4 UASB reactors. In one of them (reactor B), 25 and 50 mg FeCl3/L were dosed, and in another (reactor C) there were no dosage, serving as a reference. In each of the stages, it had been carried through around 20 samplings for COD, total and soluble phosphorus, alkalinity, pH and suspended solids. For BOD5,20ºC, total sulfides, total solids and settleable solids it had been gotten 10 values in each dosage. The collection points had been: raw wastewater and treated wastewater from reactors B and C. Samples in 3 heights of the sludge blanket had been collected and carried through the solid series analysis in each dosage. About the sludge dewatering, items as dewatering period, layer thickness and total solids had been compared in some discharges to the drying beds. From this evaluation, it can be concluded that the ferric chloride addition generates an increase of organic matter removal (from 55% to 73% of the COD and from 63% to 82% of the BOD5,20ºC, with 50 mg FeCl3/L). For phosphorus, the removal efficiencies had been lower, more noticed in the soluble portion (from 28% to 36% of total and from 0% to 59% of soluble phosphorus at 50 mg FeCl3/L). Improvement in the dewatering capacity and in sludge cake volume were also noticed. The sludge blanket showed thicker and with a lower solid concentration in the reactor with ferric chloride application, suggesting a trend to solids loss in the clarified effluent.
6

Graphene and functionalised graphene for flexible and optoelectric applications

Bointon, Thomas H. January 2015 (has links)
The landscape of consumer electronics has drastically changed over the last decade. Technological advances have led to the development of portable media devices, such as the iPod, smart phones and laptops. This has been achieved primarily through miniaturisation and using materials such as Lithium and Indium Tin Oxide (ITO) to increase energy density in batteries and as transparent electrodes for light emitting displays respectively. However, ten years on there are now new consumer demands, which are dictating the direction of research and new products are under constant development. Graphene is a promising next-generation material that was discovered in 2004. It is composed of a two-dimensional lattice made only from carbon. The atoms are arranged in a two atom basis hexagonal crystal structure which forms a fundamental building block of all sp2 hybrid forms of carbon. The production of large area graphene has a high cost, due to the long growth times and the high temperatures required. This is relevant as graphene is not viable compared to other transparent conductors which are produced on industrial scales for a fraction of the cost of graphene growth. Furthermore, graphene has a high intrinsic resistivity (2KW/_) which is three orders of magnitude greater than the current industry standard ITO. This limits the size of the electrodes as there is dissipation of energy across the electrode leading to inefficiency. Furthermore a potential drop occurs across the electrode leading to a non-uniform light emission when the electrode is used in a light emitting display. I investigate alternative methods of large area graphene growth with the aim of reducing the manufacturing costs, while maintaining the quality required for graphene human interface devices. Building on this I develop new fabrication methods for the production of large-area graphene devices which are flexible and transparent and show the first all graphene touch sensor. Focusing on the reducing the high resistivity of graphene using FeCl3 intercalation, while maintaining high optical transmission, I show low resistivity achieved using this process for microscopic graphene flakes, large-area graphene grown on silicon carbide and large-area graphene grown by CVD. Furthermore, I explore the stability of FeCl3 intercalated graphene and a process to transfer a material to arbitrary flexible substrates.

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