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Shooter, Andrew James. "Living free radical polymerisation." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263817.
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Mougnier, Sébastien-Jun. "Copolymères semi-conducteurs à architectures variées : de l'ingénierie macromoléculaire à l'électronique organique." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14675/document.
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A une époque où les technologies nouvelles fleurissent chaque jour, un domaine particulier se détache : l’électronique organique. Par son utilité et sa facilité de mise en œuvre, l’électronique organique affiche de grandes promesses pour l’avenir. Dans le but d’améliorer le procédé de fabrication et la durée de vie de ces dispositifs, le travail de cette thèse s'est focalisé sur la synthèse de copolymères à architectures variées à base de poly(3-hexylthiophène) (P3HT). Après avoir exposé les problématiques et objectifs de la thèse dans une première partie, la synthèse de différents précurseurs P3HT est décrite. Ces matériaux représentent la base des travaux présentés dans cet ouvrage. Dans un premier temps, l'optimisation de la synthèse des copolymères à blocs rigide-flexible a été réalisée en suivant une stratégie adaptée pour une application en électronique organique. La conception de nouveaux matériaux semi-conducteurs à architectures ramifiées est traitée par la suite. Enfin, le dernier chapitre porte sur l'intégration d’un copolymère, le P3HT-b-Poly(4vinylpyridine), en cellule photovoltaïque organique en tant qu'additif de la couche active. Cette approche s’avère être particulièrement puissante, permettant notamment de diminuer le temps et le coût énergétique de la mise en œuvre de ces cellules en s’affranchissant d’une étape clé de la fabrication, le recuitAt a time when new technologies emerge every day, a specific domain stands out: the organic electronic. Through its low cost processing or even its utility, the organic electronic constitutes a very promising future.In order to improve the fabrication process and the lifetime of the devices, the work of this thesis was focused on the synthesis of copolymers with various architectures based on poly(3-hexylthiophene) (P3HT). After a first part where main issues and objectives are presented, the synthesis of different P3HT-based precursors is described in a part which could be considered as the heart of these works. Starting with appropriated precursors, the optimization of rod-coil diblock copolymer synthesis was performed following a strategy designed specifically for organic electronic application. Moreover, the precursors were used for the conception of new semi-conducting materials with a variety of architectures, such as graft and star copolymers. Finally, the last part deals with the integration of the P3HT-b-Poly(4-vinylpyridine) copolymer into organic solar cell as an additive of the active layer. This approach turns out to be powerful, especially allowing decreasing the time and the energy cost by avoiding the key step of the fabrication process of those devices, the annealing step
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Gonçalves, Maria Cecilia. "Estudo experimental da polimerização via radical livre controlada em presença de radicais nitroxido (NMRP)." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266346.
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Orientador: Liliane Maria Ferrareso LonaDissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Quimica
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Resumo: A polimerização via radical livre controlada mediante radicais nitróxido (NMRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com estrutura altamente controlada. Distribuições de pesos moleculares estreitas são obtidas, com polidispersidades baixas. Neste trabalho, será estudado o processo NMRP, no qual ocorre a adição de um radical nitróxido estável, como o 2,2,6,6-tetrametil-l-piperidinoxil (TEMPO) para capturar o radical em crescimento. Embora o processo NMRP de ao polímero características controladas (polidipersidades baixas e pesos moleculares que aumentam linearmente com a conversão), ainda existe um desafio nos processos controlados, por apresentarem baixas velocidades de reação. O objetivo principal deste trabalho está focado num estudo experimental do processo NMRP visando aumentar a velocidade de reação sem perder as características principais do processo. O efeito de dois iniciadores BPO (peróxido de benzoíla) e TBEC (tert-butilperóxido-2-etilhexil carbonato) foi analisado. Observou-se que o TBEC (iniciador com constante de decomposição baixa) foi capaz de aumentar significativamente a taxa de polimerização do processo NMRP, quando comparado ao BPO, pois conversões mais altas foram obtidas, num mesmo tempo de reação, mantendo a característica controlada do sistema. O uso do TBEC apresenta uma vantagem frente ao BPO em processos controlados, não somente porque reduz o tempo de reação, mas também porque concentrações menores de iniciador e controlador foram usadas, obtendo uma taxa de reação ainda maior, o que reduz o custo operacional. Para as condições estudadas, comprovou-se experimentalmente que a taxa de reação é inversamente proporcional à concentração inicial de TEMPO, para uma mesma concentração de iniciador. A análise dos resultados através da aplicação da técnica de planejamento de experimento auxiliou numa melhor compreensão do sistema e na obtenção de condições ótimas de operação para se obter baixas polidispersidades e baixos tempos de polimerização
Abstract: NMRP process (Nitroxide Mediated Radical Polymerization) has received increasing attention as a technique for production polymers with highly controlled structures, narrow molecular weight distribution (MWD) and polydispersity index dose to 1.0. In this work 2,2,6,6-tetramethyl-l-piperidinoxyl (TEMPO) is used as the stable radical to reversibly terminate the growing polymer chain. Polymerizations were performed in ampoules, using TBEC (tert-butylperoxy-2-ethylhexyl carbonate) and BPO (benzoyl peroxide) as initiators. With the purpose of enhancing the reaction rate for NMRP process maintaining the controlled and living characteristics of the polymer synthesized (low polidispersity and molecular weights increasing linearly with conversion) an experimental study was done to evaluate the effect of two different initiators (BPO and TBEC). It was observed that TBEC (initiator with low decomposition rate) was able to enhance significant1y the polymerization rate compared to BPO, keeping the living and controlled characteristics of the system. The results show that TBEC seems to be a promising initiator that make the NMRP process more efficient, not only because it reduces the polymerization time, but also because it allows smaller amounts of controller and initiator to be used. For the operational conditions studied, experimental results with TBEC exposed that the polymerization rate in inversely proportional to the initial concentration of TEMPO, for the same amount of initiator. Using a statistical planning, it was possible to obtain a better understanding of the system and to search for operating conditions that bring low polydispersity and low reaction rates. Finally, the results are expected to have significant benefits for controlled polymerization on an industrial setting
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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Fleischmann, Sven. "Alkinhaltige Blockcopolymere und ihre Modifizierung mittels 1,3-dipolarer Cycloaddition." Doctoral thesis, München Verl. Dr. Hut, 2008. http://d-nb.info/991285212/04.
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Sieczkowska, Barbara. "Functional polymer layers with protected amines." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244668077080-12212.
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This work refers to the area of bio-nanotechnology and concerns the selective immobilization of DNA or other bio-template on microstructured gold contacts and which then permit a coordinated cooperation of several of these nanotemplate, e.g., within a microreactor. The immobilization of such nano-objects should be realized through functional thin polymer films which provide binding groups. Thus, the main aim of this work was the development of polymeric materials for thin functional films which permit to deposit on different substrates a wide variation of functional elements or metal structures and to achieve a pattern formation using optical grid methods. In order to realize this concept it was necessary to design and develop a polymer system based on suitable photolabile units and in addition having anchoring groups which attach on specific substrates like gold. In this terpolymer concept was aimed for which consists of three components with particular functions in suitable molar ratios, which allow the tune the properties of the materials, and provide: amino photolabile protected groups for the photolithographic creation of patterned areas with free amino groups, which are available for further modifications like attachment of colloids, metallization or attachment of DNA strands; disulfide derivative anchor groups providing anchoring capacity for gold surface and spacer groups for adjusting the film quality. These multifunctional terpolymers should be synthesised by free radical polymerisation of suitable monomers. Although these techniques are successful, they are limited by their complexity, rigorous synthetic demands, as well as incompatibility with many functional termolabile and highly reactive functionalities. To overcome these difficulties a polymerisation technique based on “living” free radical polymerisation has been used in this work. A highly efficient polymer-analogous modification allows to introduce the functionalities after the polymer construction reaction. The production of suitable prepolymers [poly(styrene-r-4-propargyl-oxystyrene)] was carried out with the help of a controlled synthesis methodology “nitroxide mediate radical polymerization" followed by polymer analogous reaction using one of the most efficient click reactions, the Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition between terminal acetylenes and azides to attach further functionalities through the formation of a stable 1,4-disubstituted 1,2,3-triazol ring . The combination of nitroxide mediated radical polymerization (NMRP) and click chemistry was used to produce well-defined random copolymer. It could already be shown that also block copolymers can be prepared which give the chance to combine nanostructure formation in block copolymers with special functionality. Thus, the special properties of these functional polymers like the capability for photopatterning and anchoring onto gold substrates make them very interesting for nanotechnology applicationsDiese Arbeit bezieht sich auf das Gebiet der Bionanotechnologie und betrifft ein neuartiges Verfahren zur selektiven Immobilisierung der DNA oder anderer Biomoleküle auf mikrostrukturierten Goldkontakten, welche dann ein koordiniertes Zusammenwirken von einzelnen Nanomolekülen ermöglichen, z.B. in einem Mikroreaktor. Die Immobilisierung solcher Nanoobjekte soll durch dünne Funktionsschichten realisiert werden, die die Anbindungsgruppen liefern. Folglich war das Hauptziel dieser Arbeit die Entwicklung von Polymermaterialien für dünne Funktionsschichten, die die Aufbringung einer großen Vielzahl von Funktionselementen oder metallischen Strukturen auf verschiedenen Substraten gestatten und die Strukturierung durch den Einsatz von lithographischen Methoden ermöglichen. Um dieses Konzept zu realisieren, war es notwendig, ein Polymersystem zu gestalten und zu entwickeln, welches auf geeignete photolabile Einheiten basiert und zusätzlich Ankergruppen hat, die mit spezifischen Substraten wie Gold verbunden ist. Dieses Terpolymerkonzept wurde gezielt aus drei Komponenten mit speziellen Funktionen in entsprechenden molaren Verhältnissen gebildet, die eine Abstimmung der Materialeigenschaften ermöglicht und folgendes bereitstellt: photolabile geschützte Aminogruppen für die photolitographische Strukturerzeugung mit freien Aminogruppen, welche für weitere Modifikationen verfügbar sind wie das Anhängen von Kolloiden, die Metallisierung oder Anfügung von DNA-Strängen; disulfide Derivate für die kovalente Anbindung auf der Goldoberfläche und Spacer-Gruppe für Verbesserung der Schichtenbildung. Diese multifunktionalen Terpolymere sollen durch eine freie radikalische Polymerisation von entsprechenden Monomeren synthetisiert werden. Obwohl diese Techniken erfolgreich sind, sind sie eingeschränkt durch ihre Komplexität, den strengen synthetischen Anforderungen, sowie der Inkompatibilität mit vielen funktionalen thermolabilen und hochreaktiven Funktionalitäten. Um diese Schwierigkeiten zu überwinden wurde eine Polymerisationstechnik für diese Arbeit genutzt, die auf der „lebenden“ freien radikalischen Polymerisation basiert. Eine hoch effiziente polymeranaloge Modifizierung erlaubt die Einführung von Funktionalitäten nach der Polymeraufbaureaktion. Die Herstellung von entsprechenden Präpolymeren Poly(Styrol-r-4-Propargyl-oxystyrol) wurde mittels einer kontrollierten Synthesemethodik „Nitroxid-mediated controled radical polymerisation“ (NMRP) durchgeführt, gefolgt von der Polymeranalogreaktion, die eine der effizientesten Click-Reaktion - die Cu(I) katalysierte 1,3-dipolar Cycloaddition von terminalen Alkinen an Aziden nach Huisgen nutzt, um weiter Funktionalitäten durch die Bildung eines stabilen 1,4-disubstituierten-[1,2,3]-Triazolringes anzufügen. Die Kombination von NMRP und Click-Chemie wurde zur Herstellung eines exakt definierten Random Copolymers genutzt. Es konnte bereits gezeigt werden, dass auch Blockcopolymere geschaffen werden können, die eine Möglichkeit zur Kombination von Nanostrukturformationen in Blockcopolymeren mit speziellen Funktionaltäten bieten. Folglich sind die speziellen Eigenschaften dieser Funktionalpolymere wie die Fähigkeit zur Photostrukturierung und Verankerung auf Goldsubstraten für nanotechnologische Anwendungen sehr interessant
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Nogueira, Telma Regina. "Investigação experimental da copolimerização de estireno divinilbenzeno (DVB) via radical livre controlada por radicais nitroxido (NMRP)." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267631.
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Orientador: Liliane Maria Ferrareso LonaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Polimerização via radical livre controlada, também conhecida como "pseudoliving radical polymerization" tem recebido cada vez mais atenção como uma técnica para produção de polímeros com micro estrutura altamente controlada. Em particular, distribuições de pesos moleculares estreitas são obtidas, com polidispersidade muito próxima de um. Rotas convencionais para polímeros como estes têm sido polimerizações iônicas, no entanto, elas são extremamente sensíveis a impurezas e ao tipo de solvente. Processos de polimerização via radical livre, que são muito mais versáteis e robustos a impurezas, para a produção de polímeros com estruturas controladas via processo "controlado" ou "pseudo-living", têm se tornado uma importante alternativa. Como desvantagem do processo controlado aponta-se a baixa velocidade de reação quando comparada à polimerização convencional. A maioria dos trabalhos publicados sobre polimerização controlada via radicais nitróxido é feita considerando o estudo da homopolimerização de estireno. Neste projeto de pesquisa, é investigada, em nível experimental, a co-polimerização de estireno e divinilbenzeno (DVB) via polimerização controlada por nitróxidos (NMRP) usando 2,2,6,6- tetrametil-1-piperidinoxil (TEMPO) como controlador e tert-butilperóxido-2-etilhexil carbonato (TBEC) como iniciador. O DVB funciona como gerador de ramificações na cadeia polimérica, melhorando as propriedades do estireno como resistência a solvente e ao impacto. O TBEC foi utilizado em substituição a iniciadores mais convencionais como o 2,2-azo-bis-iso-butironitrila (AIBN) e peróxido de benzoíla (BPO), com o objetivo de acelerar a velocidade de reação, tentando manter o sistema controlado. Todos os experimentos foram feitos em ampolas. Para um melhor entendimento deste sistema, muitos experimentos foram realizados a diferentes temperaturas, concentrações de divinilbenzeno, concentrações de iniciador e razões molares entre as concentrações de controlador e iniciador. A conversão do monômero foi obtida por gravimetria e o polímero foi caracterizado através de Cromatografia de Permeação em Gel (GPC). Foi demonstrado que o TBEC foi capaz de aumentar a velocidade de reação em relação ao BPO e, em algumas condições operacionais utilizadas, polidispersidades próximas da unidade foram obtidas.
Abstract: Living free radical polymerization, also known as "pseudo-living radical polymerization" has received more and more attention as a technique for the production of polymers with micro structure highly controlled (narrow molecular weights distributions and polydispersity index close to one). Conventional routes to obtain polymer like this have been ionic polymerizations, however, they are extremely sensitive to impurities and solvents. Free radical polymerizations, which are more versatile and robust to impurities, for the production of polymers with controlled structures by "controlled" or "pseudo-living" process, have become an important alternative. As a disadvantage of the controlled process can be pointed the low reaction rate when compared to the conventional process. Most of the published papers about nitroxide mediated living free radical polymerization consider the homopolymerization of styrene as case study. In this research, the co-polymerization of styrene and divinylbenzene (DVB) by living free radical polymerization (NMRP) is investigated in experimental level. The stable radical used was 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO). The initiators used in this work were tertbutylperoxy- 2-ethylhexyl carbonate (TBEC) and benzoyl peroxide (BPO). DVB acts as a branching generator, improving the properties of the styrene as the solvent and impact resistance. TBEC was used in substitution to conventional initiators as 2, 2-Azo-bisisobutyronitrile (AIBN) and BPO, with the aim of accelerating the reaction rate, trying to keep a controlled/living system. All the experiments were performed in ampoules. To better understand this system, many experiments were performed at different temperatures, divinylbenzene concentrations, initiator concentrations and molar ratios between controller and initiator. Conversion was obtained by gravimetric method and the polymer was characterized by Gel Permeation Chromatograph (GPC). It was observed that, at certain operating conditions, the TBEC initiator was able to produce copolymers with polydispersity close to unity in a much faster velocity when compared to BPO.
Mestrado
Processos Quimicos
Mestre em Engenharia Química
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Thiessen, Wladimir. "Polymere und Nanopartikel - Verfahren für die Chemische Nanotechnologie." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65374.
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In der vorliegenden Arbeit soll das weit gefächerte Thema der chemischen Nanotechnologie um neue Resultate bereichert werden. Im Einzelnen handelt es sich um neue Synthesemethoden für magnetische Nanorods (Nanoteilchen mit länglicher Form) und Nanoshells (oxidische Nanokristalle mit einer Hülle aus Edelmetall), ein Verfahren zur Modifizierung diverser Oberflächen mit heterogenen Polymerbürsten durch kontrollierte binäre radikalische Polymerisation, neuartige Copolymere zur Stabilisierung und Funktionalisierung von Nanopartikeln und Herstellung von amphiphilen Nanopartikeln durch Oberflächenbehandlung mit Niotensiden. Es sollen ferner die möglichen Anwendungen diskutiert werden. Die Abb. 1 illustriert die Zusammenhänge der bearbeiteten Thematik.
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Galhardo, Eduardo 1982. "Viabilização da polimerização mediada por nitróxidos (NMRP) em emulsão por meio da variação de parâmetros de processos." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266601.
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Orientador: Liliane Maria Ferrareso LonaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: A polimerização via radical livre controlada, também conhecida como "Living Free Radical Polymerization" (LFRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com cadeias monodispersas. Em particular, distribuições de massas moleculares estreitas são obtidas, com polidispersidade muito próxima de um. Rotas convencionais para polimerizações como esta têm sido as iônicas, no entanto, elas são extremamente sensíveis a impurezas e tipo de solvente. Desta forma, processos de polimerização via radical livre, que são muito mais versáteis e robustos a impurezas, para a produção de polímeros com estruturas controladas via processo "controlado", tem se tornado uma importante alternativa. Neste projeto de pesquisa, foi feito um estudo em nível experimental para investigar a polimerização controlada mediada por nitróxidos (NMRP, do inglês, Nitroxide Mediate Radical Polymerization), utilizando-se a polimerização em emulsão. Esse tipo de polimerização apresenta alta versatilidade industrial e também um ganho ambiental, já que um solvente orgânico é, nesse caso, substituído por água. Um dos desafios enfrentados em processar a polimerização NMRP em emulsão foi à manutenção da água em seu estado líquido, já que o processo NMRP, utilizando-se TEMPO (2, 2, 6,6-tetrametil-1-piperidinoxil) como controlador, somente se dá a uma temperatura maior que 100ºC, o que exigiu a pressurização do sistema. As quantidades de surfactante (SDS) foram alteradas de forma sistemática: 5,00 7,50 e 10,00 g. Percebeu-se que, usando 5,00g de SDS, menores polidispersidades e massas moleculares foram alcançadas, o que prova uma relação entre esses parâmetros e o número de partículas nucleadas. A relação monômero/água (v/v) também foi alterada, a saber: 0,33, 0,55, 0,70 e 0,75. Percebeu-se que a relação 0,75 forneceu as menores polidispersidades e as maiores massas moleculares. Um estudo teórico realizado com o Software Gaussian 3.0 mostrou os valores da entalpia para a espécie alquociamina dormente e para a reação global
Abstract: Controlled radicalar polymerization, known also by Living Free Radical Polymerization, has received every time more attention as being a technique for production of polymer with highly controlled microstructure. Particularly, narrow molecular weight distributions are reached, with polydispersity very close to one. Conventional routes for polymerizations like this has been the ionic, however, it is extremely sensitive to impurities and kind of solvent. This way, processes of polymerization via free radical, which are much more versatile and robust to impurities for the polymer production with controlled structures via "controlled process", has been an important alternative. In this work Nitroxide Mediated Radical Polymerization (NMRP) using TEMPO (2,2,6,6-tetrametyl-1-piperidinoxyl) as controller and emulsion polymerization was investigated. Conventional emulsion polymerization presents high industrial versatility, due to range of monomers that can be applied, and also an environmentally advantage, because an organic solvent is replaced by water. One of the challenges faced was keeping the water in liquid physical state, because the maximum efficiency of the process occurs at a temperature higher than 115ºC, what demanded the pressurization of the system. The quantities of surfactant (SDS) were systematically changed: 5.00, 7.50 and 10.00 g, respectively. It was perceived that using 5.00 g of SDS, lower values of polydispersity and molecular weight were obtained, what ensures a relation between such parameters and the number of nucleated particles. The relation monomer/water (v/v) was also changed, namely: 0.33, 0.55, 0.70 and 0.75. It was noticed that the relation 0.75 provided the lowest polydispersities and the highest molecular weights. The theoretical study performed with the Software Gaussian 3.0 showed the enthalpy values for the dormant alkoxyamine specie and for the global reaction
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
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Simms, Ryan W. "Living/controlled Polymerization Conducted in Aqueous Based Systems." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/700.
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Dias, Rafael Silva. "Investigação experimental e computacional da polimerização via radical livre controlada em presença de radicais nitroxido (NMRP) utilizando-se iniciadores difuncionais." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266460.
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Orientador: Liliane Maria Ferrareso LonaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Polimerização via radical livre controlada, ou Living Free Radical Polymerization (LFRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com micro estrutura altamente controlada. Em particular, distribuições de pesos moleculares estreitas são obtidas, com polidispersidade próxima de um. Rotas usuais para obtenção de polímeros como estes têm sido polimerizações iônicas, mas elas são extremamente sensíveis a impurezas. Dentre os processos controlados, a polimerização mediada por nitróxidos (Nitroxide-Mediated Radical Polymerization-NMRP) permite a introdução de funcionalidades químicas na cadeia polimérica e apresenta como vantagens a possibilidade de polimerizações em meio aquoso, síntese de materiais híbridos, copolímeros, além de ser a rota química com menor impacto no meio-ambiente. Contudo, um dos desafios a ser enfrentado na LFRP, inclusive na NMRP, é o aumento da velocidade de reação, uma vez que as polimerizações controladas são muito mais lentas em função da existência de uma etapa de equilíbrio intrínseca. Na busca de maiores produtividades, utilizam-se temperaturas de operação ou concentração de iniciadores monofuncionais elevadas que, por conseqüência, geram polímeros com pesos moleculares mais baixos. Nos processos de polimerização convencional, o uso de iniciadores difuncionais permite o aumento da produtividade sem alterações ou mesmo com um aumento dos pesos moleculares. Sendo assim, nesta tese, foi feito um estudo experimental (polimerização em ampolas) e de simulação (desenvolvimento de modelos determinísticos e empíricos) para investigar a NMRP, no sentido de tentar reduzir o tempo gasto na polimerização, através do uso de iniciadores difuncionais. Particularmente, foram avaliadas as massas moleculares e a polidispersidade do poliestireno sintetizado usando o TEMPO (2,2,6,6, tetrametil-1-piperidinoxil) como controlador através de uma comparação com iniciadores monofuncionais (BPO e TBEC). Através de um planejamento de experimentos, determinou-se a influência da concentração do iniciador difuncional L531, da razão controlador/iniciador, e da temperatura na conversão, nos pesos moleculares e na polidispersidade e chegou-se a um modelo empírico. Foi proposto um mecanismo de reação com a derivação de equações de balanço de massa e de momentos para um reator batelada. Fez-se um bom ajuste do modelo com a estimativa de alguns parâmetros. Finalmente, desenvolveu-se uma análise de sensibilidade (dinâmica) dos parâmetros do modelo. Ambos os resultados experimentais e de simulação mostraram que foi possível obter um aumento na conversão aliado a um incremento nas massas moleculares ao se usar o iniciador difuncional L531 em relação ao monofuncionais, sendo mantido o processo controlado. Esta abordagem é inédita, pois não foi encontrado na literatura aberta nenhum tipo de polimerização radicalar controlada por nitróxidos que faça uso de iniciadores com funcionalidade superior a um.
Abstract: Controlled/Living Free Radical Polymerization (LFRP) is one of the most important techniques for production of polymeric materials with good control of the microstructure (e.g., narrow molecular weight distributions). Such properties can also be achieved via ionic polymerizations, but being a free radical polymerization process, LFRP is much less sensitive to impurities and solvents. The Nitroxide-Mediated Radical Polymerization (NMRP), as well as other LFRP processes, provides end functional polymers, and recently it has shown advantages related to polymerization in aqueous media, synthesis of hybrid materials, block copolymers, and environmental issues. However, one challenge that still must be overcome in LFRP, as well as in NMRP process, is to increase slow polymerization rates experienced due to the establishment of an intrinsic equilibrium. In order to achieve higher productivities, higher reaction temperatures or higher (monofunctional) initiator concentrations are usually used, but as a result, polymers with lower molecular weight are produced. It is well known that the use of di-functional initiators provides an enhancement of the reaction rate of conventional free radical polymerization with either no change or even an increase in molecular weight averages. Therefore, in this thesis, it was taken an experimental (polymerization in ampoules) and computational (deterministic and empirical methods) investigation of the effect of di-functional initiators on nitroxide-mediated radical polymerization with the purpose of enhancing the reaction rate. Particularly, the molecular weight development (number average molecular weight and polydispersity) of polystyrene synthesized by using TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) as controller was evaluated by making a comparison with polymerizations using mono-functional initiators (BPO and TBEC). From the use of a design of experiments, the influence of the L531 initiator concentration, the TEMPO/initiator ratio, and the temperature on the reaction rate, molecular weights and polidispersity were determined, and an empirical model was generated. A kinetic mechanism has been proposed, from which mass balance and moment equations were derived for a batch reactor. The model was well adjusted to the experimental data with the estimation of some parameters. Lastly, a dynamic sensitivity analysis of the parameters was developed. It was shown both in experimental and simulation results that in the case of the bi-functional initiator L531, the reaction rate and molecular weights were increased when comparing to the performance of the mono-functional initiators keeping the livingness of the system. To the best of our knowledge, this is the first report of TEMPO-mediated polymerization of styrene using difunctional initiators.
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
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Corten, Cathrin Carolin. "Synthese und Charakterisierung dünner Hydrogelschichten mit modulierbaren Eigenschaften." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1209463829168-95283.
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Im Mittelpunkt dieser Arbeit stand die Darstellung sensitiver Blockcopolymere und deren Gele, die als Ausgangsmaterialien in Sensor- und Aktorsystemen einsetzbar sind. Die Vereinigung verschiedener Ansprechparameter stellt erhöhte Anforderung an die Synthese. Geringe Ansprechzeiten lassen sich mit einer Gelgröße im µm-Bereich erreichen. Hydrogele dieser Größenordnungen können durch nachträgliche Vernetzung funktioneller linearer Polymere ermöglicht werden. Die Makroinitiatormethode ermöglichte den Aufbau verschiedener linearer photovernetzbarer Blockcopolymere. Zum Einen wurde das temperatursensitive P(n-BuAc)-block-P(PNIPAAm-co-DMIAAm) erhalten, des Weiteren gelang die Darstellung der multi-sensitiven Blockcopolymere P2VP-block-P(NIPAAm-co-DMIAAm) und P4VP-block-P(NIPAAm-co-DMIAAm). Die Blockcopolymere wurden mit variierenden Blocklängen und Verhältnissen sowie mit unterschiedlichem Vernetzergehalt dargestellt. Die Charakterisierung der Blockcopolymere erfolgte mittels 1H-NMR-Spektroskopie, GPC-Messungen (Zusammensetzung) und DSC-Messungen (thermische Eigenschaften). Das Löslichkeitsverhalten in wässrigen Medien wurde durch Dynamische Lichtstreuung bestimmt. Die Beschreibung des Quellverhaltens der vernetzten Schichten erfolgte durch vornehmlich durch optische Methoden (SPR/OWS, WAMS, Ellipsometrie). Die Veränderung des E-Moduls in Abhängigkeit äußerer Parameter konnte mittels AFM untersucht werden. Die Reaktion der Schichten wurde gegenüber Temperatur, pH-Wert und Salzkonzentrationen getestet. Die charakterisierten Filme konnten im Anschluss als sensitive Schichten in piezoresistiven Sensorsystemen verwendetet werden.
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Messerschmidt, Martin. "Partiell geschützte Blockcopolymere zur Darstellung von Polymerfilmen mit strukturierbarer und modifizierbarer Morphologie." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1164976535005-04944.
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Gemäß der Zielstellung der Dissertation wurden verschiedene partiell tert.-Butyl- (TBU) und tert.-Butyloxycarbonyl- (Boc) geschützte Blockcopolymere auf der Basis von Poly(4-hydroxystyrol) mit engen Molmassenverteilungen sowie mit verschiedenen Blockzusammensetzungen dargestellt. Die Synthese dieser partiell TBU- und Boc-geschützten Blockcopolymere umfasste drei wesentliche Schritte: 1) Darstellung von Makroinitiatoren mittels NMRP, 2) Synthese von orthogonal geschützten Precursor-Blockcopolymeren durch Reinitiierung der Makroinitiatoren in Gegenwart eines weiteren orthogonal geschützten Monomeren und 3) orthogonale und quantitative polymeranaloge Umsetzungen ausgehend von den orthogonal geschützten Precursor-Blockcopolymeren. Mit den partiell TBU- und Boc-geschützten Blockcopolymeren wurden dünne Polymerfilme mittels „dip-coating“ präpariert. Die Untersuchung der Topographie und Morphologie der Filme erfolgte mit dem AFM. Aus den erhaltenen Topographie- und Phasenverschiebungsbildern ging eindeutig hervor, dass die verschiedenen Blöcke der jeweiligen partiell TBU- und Boc-geschützten Blockcopolymere in allen Polymerfilmen phasensepariert vorlagen. Reguläre Mikrostrukturen konnten allerdings nur bei den Polymerfilmen erhalten werden, deren Blockcopolymere sich allesamt durch asymmetrische Blockzusammensetzungen auszeichnen. Auf der Grundlage des statistischen Modellpolymeren Poly(styrol-r-4-hydroxystyrol) konnte ferner gezeigt werden, dass sich die phenolischen Hydroxylgruppen durch die Umsetzung mit Propargylbromid quantitativ in Propargylether-Gruppen umwandeln lassen und diese dann ihrerseits mit Hilfe der Cu(I)-katalysierten 1,3-dipolaren Cycloaddition (Click-Chemie) weiter mit einer Reihe von verschiedenen Aziden funktionalisiert werden können.
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Dolgov, Alex V. "EXPLORATION OF GRADIENT-TYPE POLY(ARYLENE ETHER)S VIA AN ABB' MONOMER SYSTEM." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1222006664.
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Hoffmann, Dirk. "NMR-Untersuchungen an Nanokapsel-Dispersionen - NMR investigations on nanocapsule dispersions." Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-05302001-102514/.
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Nanocapsules are generally considered as spherical, hollow structures. Important potential applications are pharmaceutically related such as drug targeting and controlled release. Typically, the capsules consist of a polymeric wall, filled with an oil which can dissolve lipophilic agents. To enable a stable aqueous dispersion, the capsule surface is covered by an amphiphilic surfactant. Nanocapsule-dispersions were investigated by means of solid-state nmr. Cross polarization experiments revealed the morphology of the polymeric wall. Further, the spin-lattice relaxation times for the proton magnetization in the rotating frame were studied under direct excitation as well as under cross polarization conditions. Based on the results, a special mechanism of cross polarization is proposed, initiated by a temporary adsorption of mobile oil- and surfactant-molecules to the more rigid capsule surface. - Nanokapseln sind sphärische, hohle Objekte, die in der Medizin als gewebespzifische Wirkstoff-Träger-Systeme eingesetzt werden sollen. Vereinfacht bestehen die Kapseln aus einem Öltropfen, der von einem Polymergerüst umgeben ist. In die innere Ölphase können lipophile Wirkstoffe eingeschlossen werden. Die Nanokapselwand ist mit einer Tensidschicht umgeben, die stabilisierend wirkt und ermöglicht, dass die Kapseln in einer wässerigen Phase dispergiert werden können. Als analytische Methode wurde die Festkörper-NMR-Spektroskopie gewählt. Die Morphologie der Polymerwand wurde mit Kreuzpolarisationsexperimenten aufgeklärt. Zusätzlich wurden die Relaxationszeiten im rotierenden Koordinatensystem der Protonen unter Direktanregungs- und Kreuzpolarisationsbedingungen untersucht. Die Ergebnisse dieser Untersuchungen konnten mit einer temporären Adsorption der Öl- und Tensidmoleküle an der Nanokapseloberfläche interpretiert werden.
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Lenz, Eva-Maria. "Multinuclear NMR and HPLC-NMR spectroscopic studies on xenobiotic metabolism." Thesis, Birkbeck (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267785.
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Sarala, J. (Jouni). "Low field NMR." Bachelor's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201907252707.
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Abstract. The subject of this thesis is NMR in low magnetic field. Traditionally NMR instruments utilize a superconducting high field magnet, but recently, compact instruments are getting more common with the use of lower magnetic fields. In this thesis, the basic theory of NMR is explained and the instrumentation and different ways of producing homogeneous magnetic fields are described. An experimental set-up was constructed and tested. The theory of relaxation and dependence of resonance frequency on the magnetic field were demonstrated.
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Lee, Jaehyuk. "A portable NMR." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609637.
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Karvonen, V. (Ville). "NMR-spektroskopia lääkeaineanalytiikassa." Bachelor's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201705232041.
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NMR-spektroskopia perustuu ytimien ydinmagnettisen resonanssin mittaamiseen. Menetelmä on kasvattanut suosiotaan lääkeaineanalytiikassa aina ilmiön löytämisestä lähtien. Tässä tutkielmassa perehdytään NMR-spektroskopian teoriaan ja sen käyttöön lääkeaineanalytiikassa, jossa NMR-menetelmä tulee päivä päivältä tärkeämmäksi ja yleisemmäksi. NMR-spektroskopia on nopea, informatiivinen, eikä kalliiden tai monimutkaisten standardien käyttö ole menetelmässä tarpeellista. Menetelmää voidaan periaatteessa soveltaa kaikille ydinaktiivisille ytimille, mutta yleisimmin menetelmällä mitataan 1H-ydintä.
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Vuorinen, J. (Jere). "Maaperänäytteiden NMR-analyysi." Bachelor's thesis, University of Oulu, 2018. http://urn.fi/URN:NBN:fi:oulu-201812183292.
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Tässä tutkielmassa olemme kiinnostuneita miten NMR-spektroskopiaa voidaan käyttää maaperänäytteiden tutkimiseen. Maaperässä on erilaisia hiiliyhdisteitä ja niitä voidaan havaita kiinteän aineen 13C NMR-spektroskopialla. Tutkielmassa käydään läpi perinteisen NMR:n ja kiinteän aineen NMR:n perusasioita. Lopuksi perehdytään maaperänäytteiden tutkimiseen.
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Norris, David G. "NMR flow imaging." Thesis, University of Aberdeen, 1986. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU009818.
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The phase-encoded method of NMR flow imaging is examined in detail. The motion of isochromatic groups in the direction of suitably balanced magnetic field gradients will give a phase change in the NMR signal directly proportional to the velocity, acceleration, or higher derivative of position, dependent upon the form of the field gradient. If a simple bipolar pulse is used then the phase change, for isochromats moving with constant velocity, will be proportional to the velocity. If two such pulses are placed back to back then the phase change is proportional to the acceleration. The motion of isochromats in the magnetic field gradients used for imaging will also cause phase changes. These effects are considered, and simple methods of reducing them presented. Phase errors due to main field inhomogeneity are shown to be eliminated by a simple phase difference technique. In this two image data sets having different flow sensitivities are obtained, and the phase difference between them calculated. Velocity images were obtained using this technique, both by the manipulation of the frequency-encoding and selection gradients, and by the insertion of bipolar pulses in the imaging sequence. Acceleration images were also produced by adding double bipolar pulses to the imaging sequence. Both spin-echo and field-echo sequences were used. Field-echo sequences were shown to be superior for high velocities, particularly when the direction of flow is through the slice, otherwise spin-echo sequences were preferred. The Fourier imaging of velocity is also examined, and images presented. This technique is only considered to be useful for projective imaging, where it is shown to have an SNR advantage over established methods. Using two specially designed phantoms the accuracy of all these techniques is shown to be within 5%.
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Ferrari, Maude, J. P. Mérel, Sébastien Leclerc, Christian Moyne, and Didier Stemmelen. "Study of dispersion by NMR: comparison between NMR measurements and stochastic simulation." Diffusion fundamentals 18 (2013) 11, S. 1-4, 2013. https://ul.qucosa.de/id/qucosa%3A13718.
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Dispersion remains, today, a highly topical subject. Our group has been interested in characterizing this phenomenon by pulsed-field-gradient NMR technique. Direct measurement of the dispersion coefficient can be done with a Pulsed Gradient Spin Echo (PGSE) sequence by assuming that the asymptotic regime is reached. In unsteady state, the propagator formalism is used. To better understand these measurements, the NMR experiment is modeled using a stochastic simulation (random walks) and compared with experimental results. The comparison is made for the simple case of Poiseuille flow in a circular tube (Taylor-Aris dispersion).
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Perlo, Juan. "Single sided NMR tomography /." Aachen : Shaker, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016031200&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Veitch, Nigel Charles. "NMR studies of peroxidases." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306025.
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Harvey, P. R. "Hyper-fast NMR imaging." Thesis, University of Nottingham, 1991. http://eprints.nottingham.ac.uk/13753/.
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The work presented in this thesis was carried out in the Physics Department at the University of Nottingham between October 1988 and October 1991. It is the original work of the author except where indicated by reference. This thesis describes the continuation of the development of Echo Volumar Imaging (EVI) to facilitate snapshot imaging of a volume within the human body. Variants of the technique which have also been investigated include a spin echo version, SE-EVI, and a zoomed version ZEVI. All formats acquired data in a modulus fashion in times ranging from 64 ms to 120 ms. Hardware limitations have restricted the image matrix size to 64 x 32 x 8 voxels and prompted the employment of more efficient gradient driver circuitry. A multi-mode resonant gradient circuit is described for use in both Echo Planar Imaging (EPI) and EVI. The circuit behaves in an overall resonant manner but at a fixed number of discrete frequencies. By choosing the number of resonant modes, the circuit can be used to generate approximations to a square wave or trapezoidal waveform. Because of the energy conserving nature of the circuit design much faster current rise times can be achieved with a given amplifier and gradient coil. The multi-mode gradient driver circuit was utilized both for planar imaging and to investigate the effect of rapidly modulated magnetic fields on the human body. A simple neural stimulation model is used to evaluate the stimulation threshold current density for a variety of magnetically induced waveforms and for sinusoidal stimulation as a function of frequency. Experimental results correlate well with the model showing that for short times, contrary to the widely held view, neural stimulation is independent of the magnetic field switching rate dB / dt, but depends on the final magnetic field value.
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Furby, Michael Ian Charles. "NMR of liquid crystals." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263471.
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Welch, John. "Multidimensional in vivo NMR." Thesis, University of Oxford, 2001. http://ora.ox.ac.uk/objects/uuid:876ed795-9e23-4d53-a407-0a29f7c9ea21.
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A proton nuclear magnetic resonance spectrum of the brain in vivo contains peaks from every proton-containing molecule in the brain. Sensitivity limitations mean that only those molecules present at concentrations of at least a few millimolar are detectable in a reasonable period of time; this still leaves many important molecules such as amino acids and other small metabolites. Most of their resonance frequencies fall in the region between 1.0 and 4.5 p.p.m. A typical linewidth in vivo is about 0.05 p.p.m., so the number of distinct peaks observable is restricted. The use of two-dimensional NMR techniques such as COSY can spread peaks out into a second dimension enabling otherwise overlapping peaks to be resolved. This thesis describes the development, testing and application of two such 2D NMR pulse sequences, dubbed ISIS-COSY and ISIS-JRES. They are based on an existing magnetisation localisation sequence and excite detected magnetisation in a manner analogous to the high-resolution sequences COSY and 2D J-resolved spectroscopy. A method for quantifying the metabolites visible in an ISIS-COSY spectrum from their cross-peak intensities is described, and results presented from both control rat brains and those of animals treated with vigabatrin, an inhibitor of GABA-transaminase that has the effect of increasing brain γ-amino butyric acid (GABA) levels. Further applications mentioned are in the study of neutrophil-infiltrated rat brain and adaptation of the ISIS-COSY technique for human use.
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Jaroszkiewicz, E. M. "NMR of entangled polymers." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371126.
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McJury, Mark. "NMR microscopy at 500MHz." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293694.
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Rourke, David E. "Selective pulses in NMR." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259620.
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Cheah, Kien Yoo. "NMR studies of catalysis." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262980.
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Ghaoui, Nora. "Process applications of NMR." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621156.
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Bushell, Mary-Clare. "Intermediate scale NMR imaging." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847283/.
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The design, construction and calibration of an intermediate scale NMR imaging system is described. The system is based on a 7" diameter, room temperature bore superconducting magnet at a field of 0.4T. Using selective excitation and projection reconstruction techniques, the production of density, spin-lattice and spin-spin relaxation weighted images has been achieved. An investigation of the feasibility of in-vivo tissue characterisation using NMR parameters has been carried out. Tissue characterisation using healthy animals of different ages, sex and species has shown that characterisation with the NMR parameters of T1** and T2** is feasible on a given system, where 1/T1** and 1/T2** are the spin-lattice and spin-spin relaxation rates calculated from the images assuming these rates to be mono-exponential. It is shown that the scatter in results which previously was believed by other authors to be due to biological variation is in fact due to experimentation and instrumentation, and that the biological limit has yet to be reached. The successful employment of quantitative characterisation in the observation and monitoring of diseased states is illustrated by two examples. The first shows the growth of a tumour and the second uses T1* to observe the effect of toxic drugs on the kidney. In the latter case, little evidence of damage was visible on the image. Following characterisation, it is demonstrated that it is possible to optimise an imaging sequence by careful selection of the timing parameters. Optimisation of the sequences used in this work gave an increase of upto a factor of two in the signal-to-noise ratio and increased the accuracy of the relaxation rate evaluation. Finally, a technique for obtaining a map of the spatial distribution of the molecular translational diffusion coefficient together with perfusion and flow information has been developed. These parameters may well enhance the contrast as well as providing new information on the biological system.
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Bendell, David. "NMR of mycoprotein systems." Thesis, University of Sunderland, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284753.
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Gerhalter, Teresa. "Characterization of the dystrophic muscle by ²³Na NMR and ¹H NMR T₂ spectrum." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS219/document.
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Le but de la thèse était d'étudier la sensibilité de nouveaux biomarqueurs RMN visant à quantifier les changements pathologiques dans le muscle dystrophique. La dystrophie musculaire (DM) désigne un groupe hétérogène de maladies avec une atrophie musculaire progressive associée à un état de faiblesse. Elle est caractérisée par des degrés variables de nécrose, de régénération, de troubles de l'homéostasie ionique, d'inflammation chronique et finalement par le remplacement des muscles par du tissu fibro-graisseux. Mon objectif était d’évaluer la RMN du ²³Na et les techniques avancées de mesure du temps de relaxation transversal ¹H (T₂) en tant que des biomarqueurs sensibles et précoces. La RMN du ²³Na mesure les concentrations de sodium étroitement contrôlées et donne sa distribution dans le tissu. Cette information peut être utilisée pour évaluer l'homéostasie ionique et l'intégrité cellulaire. Cependant, la concentration in vivo en ²³Na est faible, la RMN du ²³Na souffre donc d'une faible sensibilité par rapport à ¹H. L’altération du T₂ ¹H du muscle, communément interprétée comme un indicateur de l'activité de la maladie, est liée à une variété d’événements non-spécifiques tels que l'œdème, l'inflammation ou la nécrose, qui précèdent le remplacement musculaire par la graisse. Des protocoles comprenant diverses méthodes de RMN du ²³Na et de ¹H T₂ ont été mis en œuvre pour évaluer les tissus musculaires squelettiques sains et dystrophiques sur des modèles animaux et sur patients. Ce travail fournit des preuves que la RMN du ²³Na pourrait offrir un biomarqueur sensible capable de surveiller l'altération spécifique du muscle dystrophique à un stade très précoceThe aim of the thesis is to investigate the sensitivity of novel NMR outcome measures (OM) aiming to quantify pathological changes in the dystrophic muscle. Muscular dystrophy (MD) refers to a heterogeneous group of diseases with progressive muscle wasting and associated weakness characterized by variable degrees of necrosis, regeneration, ionic homeostasis disturbances, chronic inflammation, and, ultimately, resulting in the replacement of muscles by fibro-fatty tissue. My focus was on the evaluation of ²³Na NMR and advanced ¹H transverse relaxation time (T₂) techniques as early, sensitive OM. ²³Na NMR measures the tightly controlled sodium concentrations and distribution in skeletal muscle tissue. This biophysical information can be used to assess ion homeostasis and cell integrity. However, ²³Na NMR suffers from a low sensitivity and in vivo concentration compared to ¹H. Alterations in the muscle ¹H T₂, commonly interpreted as an indicator of disease activity, are linked to a variety of non-specific events like oedema, inflammation, or necrosis that precede the actual muscle replacement by fat. Protocols including different ²³Na NMR and ¹H T₂ methods were implemented to evaluate healthy and dystrophic skeletal muscle tissues of animal models and patients. This work provides evidence that ²³Na NMR could offer a sensitive outcome measure able to monitor specific alteration of the dystrophic muscle at a very early stage
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Francke, Volkhard. "Festkörper-NMR-, 129Xe-NMR- und BET-Studien an adsorbierten benzoiden Verbindungen auf mesoporösen Materialien." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964532301.
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Wiesmath, Anette. "NMR methods for strongly inhomogeneous magnetic fields: application on elastomers using the NMR-mouse." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=96487721X.
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Hartl, Rainer. "Berechnung der NMR-Struktur der PPARgamma-LBD und Hochdruck-NMR-Messungen an HPr I14A." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2009/1025/.
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Uluca, Boran [Verfasser]. "Solid-State NMR and DNP-Enhanced NMR Studies on Intrinsically Disordered Proteins / Boran Uluca." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2018. http://d-nb.info/1164763237/34.
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Dvoyashkina, Nina, Dieter Freude, Christopher F. Seidler, Michael Wark, and Jürgen Haase. "Composite fuel cell materials studied by MAS PFG NMR diffusometry and MAS NMR spectroscopy." Diffusion fundamentals 24 (2015) 12, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14526.
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Palfreyman, Stuart A. "Sonically induced narrowing of the NMR spectra of solids and other novel NMR techniques." Thesis, Aston University, 1996. http://publications.aston.ac.uk/9610/.
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A typical liquid state NMR spectrum is composed of a number of discrete absorptions which can be readily interpreted to yield detailed information about the chemical environment of the nuclei found within the sample. The same cannot be said about the spectra of solid samples. For these the absorptions are typically broad, featureless and yield little information directly. This situation may be further exacerbated by the characteristically long T1 values of nuclei bound within a solid lattice which, consequently, require long inter-sequence delays that necessitate lengthy experiments. This work attempts to address both of these inherent problems. Classically, the resolution of the broad-line spectra of solids into discrete resonances has been achieved by imparting to the sample coherent rotation about specific axes in relation to the polarising magnetic field, as implemented in the magic-angle spinning (MAS) [1], dynamic angle spinning (DAS) [2] and double rotation (DOR) [3] NMR experiments. Recently, an alternative method, sonically induced narrowing of the NMR spectra of solids (SINNMR) [4], has been reported which yields the same well resolved solid-state spectra as the classic solid-state NMR experiments, but which achieves the resolution of the broad-line spectra through the promotion of incoherent motion in a suspension of solid particles. The first part of this work examines SINNMR and, in particular, concentrates on ultrasonically induced evaluation, a phenomenon which is thought to be essential to the incoherent averaging mechanism. The second part of this work extends the principle of incoherent motion, implicit in SINNMR, to a new genre of particulate systems, air fluidized beds, and examines the feasibility of such systems to provide well resolved solid state NMR spectra. Samples of trisodium phosphate dodecahydrate and of aluminium granules are examined using the new method with partially resolved spectra being reported in the case of the latter.
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Dvoyashkina, Nina, Dieter Freude, Christopher F. Seidler, Michael Wark, and Jürgen Haase. "Composite fuel cell materials studied by MAS PFG NMR diffusometry and MAS NMR spectroscopy." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198097.
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Schmid, Michael. "NMR investigations on alkali intercalated carbon nanotubes." [S.l. : s.n.], 2005. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-25673.
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Khajeh, Maryam. "Kinetic measurements using time-resolved NMR spectroscopy." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/kinetic-measurements-using-timeresolved-nmr-spectroscopy(aae85bb3-de19-450a-96ab-50e2dfd89da7).html.
Full textAbstract:
Many thousands of pounds are spent every year by pharmaceutical companies on understanding the mechanisms and kinetics of chemical reactions involved in drug discovery and production. NMR spectroscopy is often at the core of these studies as it is a powerful, non-destructive method for structure elucidation. As such investigations can be time-consuming and cost-inefficient, AstraZeneca, the project sponsor, is interested in more efficient methods for studying the kinetics of pharmaceutical reactions. In this work a number of different techniques have been devised, studied, and implemented to study the kinetics of chemical reactions by time-resolved NMR spectroscopy, in which every species in a reaction can be monitored simultaneously. These novel techniques allow the study of reactions which are difficult or impossible to study by conventional NMR methods (such as heterogeneous reactions), or which are complicated by having overlapping signals. It is possible to monitor the kinetics of a reaction very simply by acquiring a series of 1H spectra, and obtaining the integrals of the signals by least squares fitting. This technique has been used for kinetic studies of static and on-flow reactions. In the static systems the reaction mixture was placed in the normal NMR tube in the magnet, while in the flow system the reaction mixture was placed outside of the magnet, and the solution flowed through an NMR tube placed in the magnet. The novel flow system designed, constructed and tested here has been used for kinetic studies of illustrative homogeneous and heterogeneous reactions, and is suitable for use in a wide range of NMR instrumentation. Kinetic studies have also been carried out by acquiring a series of DOSY datasets, analysing the results using the multi-way method PARAFAC (PARAllel FACtor analysis). A series of DOSY datasets contains multivariate information on spectrum, time evolution and diffusion. Without providing any predetermined model, the data can be decomposed by PARAFAC to yield the spectrum, kinetics, and diffusion profiles for each of the components. It has also been shown that PARAFAC is remarkably robust to low signal-to-noise ratio data, significantly below the level at which conventional methods would fail.
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Boero, Giovanni. "Integrated NMR probe for magnetometry /." [S.l.] : [s.n.], 2000. http://library.epfl.ch/theses/?nr=2211.
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Schick, Martin Christopher. "High pressure NMR of ubiquitin /." Zürich, 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12586.
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Kaufmann, Ilja. "Funktionelle NMR-Mikroskopie an Pflanzenwurzeln." kostenfrei, 2008. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2009/3415/.
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Rademacher, Martin. "NMR-spektroskopische Untersuchungen an Fettsäurebindungsproteinen." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964224984.
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Titze, Andreas. "87Rb-NMR-Untersuchungen an Trirubidiumhydrogendisulfat." [S.l. : s.n.], 2000. http://ArchiMeD.uni-mainz.de/pub/2000/0113/diss.pdf.
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Gröger, Adriane. "NMR-spektroskopische Untersuchungen von Proteinen." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962026921.
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Nikkhou, Aski Sahar. "NMR Studies of Inclusion Compounds." Doctoral thesis, Stockholm University, Department of Physical, Inorganic and Structural Chemistry, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8223.
Full textAbstract:
This thesis presents the application of some of the NMR methods in studying host-guest complexes, mainly in solution. The general focus of the work is on investigating the reorientational dynamics of some small molecules that are bound inside cavities of larger moieties. In the current work, these moieties belong to two groups: cryptophanes and cyclodextrins. Depending on the structure of the cavities, properties of the guest molecules and the formed complexes vary. Chloroform and dichloromethane are in slow exchange between the cage-like cavity of the cryptophanes and the solvent, on the chemical shift time scale, whereas adamantanecarboxylic acid, quinuclidine and 1,7-heptanediol in complex with cyclodextrins are examples of fast exchange. Kinetics and thermodynamics of complexation are studied by measuring exchange rates and translational self-diffusion coefficients by means of 1-dimenssional exchange spectroscopy and pulsed-field gradient (PFG) NMR methods, respectively. The association constants, calculated using the above information give estimates of the thermodynamic stability of the complexes. Carbon-13 spin relaxation data were obtained using conventional relaxation experiments, such as inversion recovery and dynamic NOE, and in some cases HSQC-type (Hetereonuclear Single Quantum Correlation Spectroscopy) experiments. Motional parameters for the free and bound guest, and the host molecules were extracted using different motional models, such as Lipari-Szabo, axially symmetric rigid body, and Clore models. Comparing the overall correlation times and the order parameters of the free and bound guest with the overall correlation time of the host molecule one can estimate the degree of the motional restriction, brought by the complexation, and the coupling between the motion of the bound guest and the reorientation of the host molecule. In one case, the guest motions were also investigated inside the cavities of a solid host material.