Yes / Organic photovoltaics (OPVs) die due to their interactions with environmental gases, i.e., moisture and oxygen, the latter being the most dangerous, especially under illumination, due to the fact that most of the active layers used in OPVs are extremely sensitive to oxygen. In this work we demonstrate solution-based effective barrier coatings based on composite of poly(vinyl butyral) (PVB)and mica flakes for the protection of poly (3-hexylthiophene) (P3HT)-based organic solar cells (OSCs)against photobleaching under illumination conditions. In the first step we developed a protective layer with cost effective and environmentally friendly methods and optimized its properties in terms of transparency, barrier improvement factor, and bendability. The developed protective layer maintained a high transparency in the visible region and improved oxygen and moisture barrier quality by the factor of ~7. The resultant protective layers showed ultra-flexibility, as no significant degradation in protective characteristics were observed after 10 K bending cycles. In the second step, a PVB/mica composite layer was applied on top of the P3HT film and subjected to photo-degradation. The P3HT films coated with PVB/mica composite showed improved stability under constant light irradiation and exhibited a loss of <20% of the initial optical density over the period of 150 h. Finally, optimized barrier layers were used as encapsulation for organic solar cell (OSC) devices. The lifetime results confirmed that the stability of the OSCs was extended from few hours to over 240 h in a sun test (65◦C, ambient RH%) which corresponds to an enhanced lifetime by a factor of 9 compared to devices encapsulated with pristine PVB. / Higher Education Commission of Pakistan through NED University of Engineering and Technology, Karachi, Pakistan and “The APC was funded by Deanship of Scientific Research, King Saud University for funding through Vice Deanship of Scientific Research Chairs”.

The hyperfine interaction between carrier spins and nuclear spins is an important component in exploring spin-dependent properties in materials with strong spin orbit interaction.However hyperfine interaction has been less studied in bismuth (Bi), a heavy element exhibiting a strong Rashba-like spin-orbit interaction in its two-dimensional surface states due to the broken spatial inversion symmetry. In this dissertation we experimentally explore the carrier spin polarization due to transport under strong spin-orbit interaction and the nuclear polarization resulting from the relatively unexplored hyperfine interaction on Bi(111) films.The carrier and nuclear spin polarizations are expected to dynamically interact, a topic with ramifications to other materials where surface states with noteworthy properties play a role.To achieve this goal, an optimized van der Waals epitaxy growth technique for Bi(111) on mica substrates was developed and used, resulting in flat Bi surfaces with large grain sizes and a layered step height of 0.39±0.015 nm, corresponding to one Bi(111) bilayer height. A comparison between Bi(111) films grown on three different substrates (mica, InSb(111)B, and Si(111)) is discussed, for which scanning electron microscopy and atomic force microscopy are applied to obtain the structural and morphological characteristics on the film surface. Magnetotransport measurements are carried out to extract the transport properties of theBi(111) films. Using the high quality Bi(111) film deposited on mica, we develop quantum magnetotransport techniques as delicate tools to study hyperfine interaction. The approach is based on measuring quantum corrections to the conductivity due to weak antilocalization, which depend on the coherence of the spin state of the carriers. The carrier spin polarization is generated by a strong DC current in the Bi(111) surface states (here called the Edelstein effect), which then induces dynamic nuclear polarization by hyperfine interaction. Quantum transport antilocalization measurements in the Bi(111) thin-films grown on mica indicate a suppression of antilocalization by the in-plane Overhauser field from the nuclear polarization, and allow for the quantification of the Overhauser field, which is shown to depend on both polarization duration and the DC current magnitude. Various delay times between the polarization and the measurement result in an exponential decay of the Overhauser field, driven by relaxation time T1. We observe that in the Bi surface states, the appreciable electron density and strong spin-orbit interaction allow for dynamic nuclear polarization in the absence of an external magnetic field. / Doctor of Philosophy / This dissertation focuses on the heavy element bismuth (Bi), a semimetal with strong spin-orbit interaction at its two-dimensional surface. Given the challenge to grow high qualityBi(111) films, we present an optimized van der Waals epitaxy technique to grow Bi(111)films on mica substrates, which show a flat surface with large grain sizes and a layered step height of 0.391±0.015 nm, corresponding to one Bi(111) bilayer height. To demonstrate the high quality of the Bi(111) surface, a comparison of surface morphology was conducted among Bi(111) films deposited on three different substrates (mica, Si(111), and InSb(111)B),along with a comparison between their electronic transport properties. By applying a DC current on the high quality Bi(111) film on mica, a carrier spin polarization is established via mainly what we here call the Edelstein effect, which then induces dynamic nuclear polarization by hyperfine interaction and generates a non-equilibrium nuclear spin polarization without externally applied magnetic field. We quantified the Overhauser field from the nuclear polarization all-electrically by conducting quantum transport antilocalization experiments, which showed a suppression of antilocalization by the in-plane Overhauser field.Comparative measurements indicated that the magnitude of the Overhauser field depends onthe spin-polarizing DC current magnitude and the polarization duration. The experiments also show that antilocalization forms a sensitive probe for hyperfine interaction and nuclear polarization.

No description available.

Les fouilles archéologiques menées dans le cadre des travaux de contournement de la municipalité de Longue Rive, en Haute-Côte-Nord, par le Ministère des Transports du Québec en 2013 ont permis la récolte d'un nombre impressionnant d'artefacts en pierre taillée associés à une occupation à influence Meadowood (3 000 à 2 400 AA). Plus de 80 % des artefacts sont issus du façonnage d'outils dans une matière première d'origine régionale, le quartzite à mica. Ce mémoire a pour but d'apporter des précisions quant à la nature de ce matériau important dans la technologie lithique nord-côtière. Nous analysons sa variabilité au sein de l'assemblage récolté sur le site DdEh-8 et proposons une caractérisation plus précise basée sur la pétrographie sur lames minces. L'analyse pétrographique suggère qu'un phénomène de mylonitisation en marge d'une zone de cisaillement pourrait être à l'origine de la formation du quartzite à mica. Quatre variétés sont décrites et leur utilisation dans l'outillage est documentée au moyen d'analyses typomorphologiques et technologiques détaillées. La production bifaciale dont l'importance dans le corpus technologique de DdEh-8 est accentuée par le façonnage systématique de « préformes quaternaires » de style Meadowood est examinée en profondeur. Le classement par stade de réduction des pièces bifaciales est confronté à une méthode de classification dite en continuum et qui corrèle les données objectives relatives à la longueur de la marge bifaciale et au nombre d'enlèvements. Il appert que la réduction bifaciale menée sur le site n'est pas aussi phasée que l'on pourrait s'y attendre bien que l'objectif de cette taille se concentre vers la production de préformes quaternaires. Le quartzite à mica semble hautement privilégié dans cette industrie bifaciale pour des raisons pratiques, en ce qui a trait à l'accès à cette matière régionale, et des raisons idéologiques, par la valeur associée ailleurs au quartzite blanc. / Archaeological excavations at the DdEh-8 site carried out by the Ministère du Transport du Québec in 2013 as part of the Longue-Rive municipality highway bypass project in the Upper North Shore region produced an artifact collection associated with a Meadowood occupation (3000 to 2400 AA). More than 80% of the artifacts recovered are derived from the production of tools from a micaceous quartzite specific to this region. Lithologic variability of this regional micaceous quartzite remains poorly understood and its origin unknown. This thesis seeks to clarify the nature of this raw material which is ubiquitous in lithic assemblages from North Shore archaeological sites. We analyze the lithological variability of this material within the assemblage recovered at the DdEh-8 site and propose a more precise characterization based on thin-section petrography. This micaceous quartzite appears to be the result of mylonitization through shear zone deformation. Four main varieties are described and their use in tool production is documented using detailed typo-morphological and technological analyses. This thesis examines the production of lithic bifaces at DdEh-8 in depth; bifacial tools are a particularly significant part of the collection due to the systematic production of Meadowood-style “quaternary preforms” at the site. The classification of bifaces by stage of reduction was undertaken with a continuum approach correlating bifacial margin length with flake removal scar frequency. It appears that the reduction of bifaces at DdEh-8 is not strictly phased in clear technological steps although the objective of this reduction is indeed focused on the production of quaternary preforms. Mica quartzite is a highly favoured raw material in this bifacial industry for reasons that appear to us to be both practical and ideological; this material is both suitable and widely available in the region, while white quartzites appear to have been preferred in general elsewhere in the Meadowood Interaction Sphere.

Atualmente, a participação da energia elétrica na matriz energética mundial é um assunto em evidência. O estudo do compósito isolante da barra estatórica, um dos componentes principais da máquina hidrogeradora, permite a obtenção de informações físico-químicas relevantes ao aperfeiçoamento do sistema, e também de estudos de comportamento térmico quando este é exposto à alta temperatura, por diferentes intervalos de tempo submetidos a estresses mecânicos, elétricos e/ou químicos. O sistema em estudo é o MICALASTIC®, desenvolvido pela empresa Siemens em 1960. Neste trabalho, as propriedades térmicas do compósito isolante, formado por uma fita de mica, resina epóxi (DGEBA), endurecedor (MHHPA) e acelerador naftenato de zinco (N-Zn) foram estudadas. Utilizando-se as técnicas termoanalíticas Calorimetria Exploratória Diferencial (DSC) e Termogravimetria e Termogravimetria Derivada (TG/DTG), o comportamento térmico de cada um dos materiais foi avaliado. As curvas DSC e TG/DTG também evidenciaram as possíveis interações químicas entre os componentes. Os estudos referentes à cura do material e da degradação térmica do compósito curado foram realizados. Observou-se claramente a influência da quantidade de acelerador na polimerização do sistema. A partir das curvas DSC, observou-se dois mecanismos de cura diferentes coexistentes, um com menor quantidade de N-Zn e outro com concentração maior, resultando em eventos de cura com início em temperaturas diferentes. Esse fato ainda não havia sido estudado desde a origem do sistema. Além disso, a perda de massa referente à evaporação do endurecedor no início do processo de cura foi confirmada a partir da caracterização do compósito por espectroscopia de absorção na região do infravermelho, comparando-se os espectros antes e após o fenômeno. Na prática, dois perfis de impregnação, o Homogêneo e o Heterogêneo, de barras condutoras são utilizados, e uma diferença significativa entre eles foi observada. Os estudos desenvolvidos devem ser associados a testes elétricos específicos para o melhor entendimento da relação entre a aplicação do material e suas propriedades teóricas termoanalíticas. Além disso, foi realizado o estudo cinético da decomposição térmica do compósito curado por métodos termogravimétricos, isotérmico e dinâmico. / Currently, the electric energy participation in the world energy matrix is a significant issue. The insulating composite in stator bars, which are one of the most important components in hydrogenerator machines, allows the attainment of relevant physical and chemical information to system optimization, in addition to study thermal behavior when the material is exposed to high temperatures, for different time intervals and mechanical, chemical and/or electrical stress. The studied system is MICALASTIC®, developed by Siemens Company in 1960. In this work, thermal properties of this insulating composite, composed by mica tape, epoxy resin (DGEBA), hardener (MHHPA) and zinc naphtenate (N-Zn) as accelerator, were studied. Using thermoananalytical techniques as Differential Scanning Calorimetry (DSC) and Thermogravimetry and Derivative Thermogravimetry (TG/DTG), thermal behavior of each material was evaluated. DSC and TG/DTG curves evidenced chemical interactions between components. The study relative to material curing and cured composite thermal degradation were described. It was clearly observed the N-Zn amount influence in the cure of system, and through DSC curves, it was possible to observe two distinct polymerization coexisting mechanisms, one with lower quantity of N-Zn and another one with bigger concentration, resulting in cure events starting in different temperatures. This fact has not been studied yet since the system has been originated. Besides that, the weight loss related to hardener evaporation starting with curing process was confirmed by composite characterization by FTIR spectra, before and after phenomenon. In practice, two impregnation patterns (Homogeneous and Heterogeneous) of conductive bars are used and a significant difference between them was observed. The developed studies have to be associated to electrical tests to a best understanding about material application and theoretical thermoanalytical properties. In addition, it was performed thermal decomposition of cured composite kinetic study by isothermic and dynamic thermogravimetric methods

Submitted by PPG Servi?o Social (servico-social-pg@pucrs.br) on 2017-10-06T20:16:53Z No. of bitstreams: 1 Paulo Roberto Martins - Disserta??o.pdf: 1278248 bytes, checksum: ea7a78a1e4d25cf3239be8795c034e84 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-10-09T13:52:31Z (GMT) No. of bitstreams: 1 Paulo Roberto Martins - Disserta??o.pdf: 1278248 bytes, checksum: ea7a78a1e4d25cf3239be8795c034e84 (MD5) / Made available in DSpace on 2017-10-09T13:57:46Z (GMT). No. of bitstreams: 1 Paulo Roberto Martins - Disserta??o.pdf: 1278248 bytes, checksum: ea7a78a1e4d25cf3239be8795c034e84 (MD5) Previous issue date: 2017-08-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / El tema de este estudio es la pol?tica de asistencia social enfocada en el medio rural, delimitando el an?lisis en el municipio de Alegrete en Rio Grande do Sul, espec?ficamente en el asentamiento del MST "Novo Alegrete". El objetivo general de esta disertaci?n es investigar la materializaci?n de la pol?tica de asistencia social, considerando la din?mica socio-hist?rica brasile?a en el medio rural, a trav?s del acceso a sus servicios p?blicos ofrecidos a la rural, a fin de contribuir en la posible ampliaci?n y en la planificaci?n de acciones para esta pol?tica. Se busca responder al siguiente problema de investigaci?n: ?Cu?l es el impacto de la din?mica socio-hist?rica capitalista en la materializaci?n de la pol?tica de asistencia social en medio rural? La investigaci?n es de tipo cualitativo, de car?cter exploratorio, se refiere en el m?todo dial?ctico cr?tico, as? como sus categor?as de an?lisis (historicidad, contradicci?n y totalidad) como base te?rica. Como categor?as explicativas de la realidad se utiliza: proceso subsistencia; necesidad de infraestructura y servicios; preconcepto; din?mica estructural de atenci?n; prestaci?n de los servicios de la pol?tica de asistencia social y las condiciones de trabajo de los profesionales; que surgieron del an?lisis de las informaciones obtenidas junto a los (as) participantes de la investigaci?n. Los datos fueron obtenidos a trav?s de la entrevista semiestructurada con gestor, profesional t?cnico de la pol?tica de asistencia social y usuarios que viven en el medio rural, utilizando el an?lisis de contenido como t?cnica para captar los elementos emergidos de los testimonios de los sujetos entrevistados. En lo que se refiere a los resultados de la investigaci?n, demostraron que el impacto de la din?mica socio-hist?rica brasile?a en el medio rural brasile?o es el mantenimiento de la desigualdad social, principalmente de la concentraci?n de la propiedad en manos de pocos propietarios, adem?s, los indicadores sociales revelan que la pobreza es estructurante al propio desarrollo del capitalismo. El pacto con las ?lites agrarias se ha mantenido y con ello los proyectos que visan democratizar la sociedad brasile?a todav?a est?n "maneados", bloqueados por las fuerzas conservadoras que sostienen sus intereses a trav?s de la reproducci?n de la pobreza del Esta din?mica influye directamente en la materializaci?n de la pol?tica de asistencia social el medio rural, donde a?n se ve la dificultad de su inserci?n, limitando sus actividades a la atenci?n individual, los (as) profesionales tienen que dividirse entre la poblaci?n urbana y del campo, que debido a la intensa demanda de los primeros, acaban quedando en segundo plano. / O tema deste estudo ? a pol?tica de assist?ncia social voltada para o meio rural, delimitando-se a an?lise no munic?pio de Alegrete no Rio Grande do Sul, especificamente no assentamento do MST ?Novo Alegrete?. O objetivo geral desta disserta??o ? investigar a materializa??o da pol?tica de assist?ncia social, considerando a din?mica s?cio-hist?rica brasileira no meio rural, atrav?s do acesso aos seus servi?os p?blicos oferecidos a popula??o rural, afim de contribuir na poss?vel amplia??o e no planejamento de a??es para esta pol?tica. Busca-se responder ao seguinte problema de pesquisa: Qual o impacto da din?mica s?cio-hist?rica capitalista na materializa??o da pol?tica de assist?ncia social no meio rural? A pesquisa ? de tipo qualitativa, de car?ter explorat?ria, referencia-se no m?todo dial?tico cr?tico, bem como suas categorias an?lise (historicidade, contradi??o e totalidade) enquanto base te?rica. Enquanto categorias explicativas da realidade utiliza-se processo de subsist?ncia; necessidade de infraestrutura e servi?os; preconceito; din?mica estrutural de atendimento; presta??o dos servi?os da pol?tica assist?ncia social e condi??es de trabalho dos profissionais; que emergiram da an?lise das dos (as) participantes da pesquisa. A coleta de dados se deu atrav?s da entrevista semi-estruturada com gestor, profissional t?cnico da pol?tica de assist?ncia social e usu?rios que vivem no meio rural, onde utilizou-se a an?lise de conte?do enquanto t?cnica para captar elementos emergidos das falas dos sujeitos entrevistados. No que se refere aos resultados da pesquisa, demonstraram que o impacto da din?mica s?cio-hist?rica brasileira no meio rural brasileiro ? a manuten??o da desigualdade social, principalmente da concentra??o da propriedade nas m?os de poucos propriet?rios, al?m disso, os indicadores sociais revelam que pobreza ? estruturante ao pr?prio desenvolvimento do capitalismo. O pacto com as elites agr?rias vem mantendo-se e com isso os projetos que visam democratizar a sociedade ainda est?o ?maneados?, contidos pelas for?as conservadoras que sustentam seus interesses atrav?s da reprodu??o da pobreza do campo. Esse din?mica influencia diretamente na materializa??o da pol?tica de assist?ncia social para o meio rural, onde ainda se v? a de sua inser??o no meio rural, restringindo suas atividades a atendimento individuais, os (as) profissionais t?m que dividir-se entre a popula??o urbana e do campo, que devido a intensa demanda dos primeiros, acabam ficando em segundo plano.

Made available in DSpace on 2015-12-04T11:45:34Z (GMT). No. of bitstreams: 1 Robson_de_Oliveira.pdf: 643288 bytes, checksum: 18329e7e7b1f697d21ecb335826fcf40 (MD5) Previous issue date: 2005-08-29 / The companies, as integrant part of the society, are being forced to meet environmental goals, besides the economical ones, demonstrating that besides the economical return generated to the shareholders, they are also creating social return to the communities where they are located. Environmental Accounting is the system of information which main aim is to gather, measure and disclose the environmental transactions seeking to exercise the important role of communication vehicle between company and society. In this context, the accounting statements deserve attention and special study, regarding that they represent the main disclosure channel of economic-environmental items of which the Accounting uses. The objective of this work was to analyze a sample of accounting statements published in Brazil with the objective of verifying how the investments, liabilities and environmental costs have been disclosed. Unhappily, the accounting statements of this companies had revealed little adequate to the new necessities of the users of the accounting information, and parallel, insufficient to take care of to the requirements of NBC T 15 - Information of Social and Ambient Nature, approved for the Resolution of the Federal Advice of Accounting - CFC n?? 1.003, that it will enter in vigor from 1?? of January of 2006. / As empresas, como parte integrante da sociedade, est??o sendo fortemente demandadas a cumprirem metas ambientais, al??m das econ??micas; demonstrando que, al??m do retorno econ??mico gerado aos acionistas, tamb??m est??o gerando retorno social ??s comunidades em que se encontram inseridas. A Contabilidade Ambiental apresenta-se como o sistema de informa????es que tem como finalidade principal coletar, mensurar e evidenciar as transa????es ambientais visando a exercer o importante papel de ve??culo de comunica????o entre a empresa e a sociedade. Neste sentido, as demonstra????es cont??beis merecem aten????o e estudo especiais, haja vista que representam o principal canal de evidencia????o de itens econ??mico-ambientais do qual faz uso a Contabilidade. O objetivo deste trabalho foi o de analisar uma amostra de demonstra????es cont??beis publicadas no Brasil, das empresas Petrobr??s, Braskem, Refap, Copesul, Bunge Fertilizantes, Basf, Petroqu??mica Uni??o e OPP, todas do ramo qu??mico e petroqu??mico, no intuito de verificar como t??m sido evidenciados os investimentos, passivos e custos ambientais pelas referidas empresas. Infelizmente, as demonstra????es cont??beis dessas companhias mostraram-se pouco adequadas ??s novas necessidades dos usu??rios da informa????o cont??bil, e paralelamente, insuficientes para atender ??s exig??ncias da NBC T 15 - Informa????es de Natureza Social e Ambiental, aprovadas pela Resolu????o do Conselho Federal de Contabilidade - CFC n?? 1.003, que entrar?? em vigor a partir de 1?? de janeiro de 2006.

Made available in DSpace on 2014-12-17T15:41:54Z (GMT). No. of bitstreams: 1 AlineMSS_DISSERT.pdf: 3248448 bytes, checksum: 238473f18fc530ccf887915ce75c940d (MD5) Previous issue date: 2011-07-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work, electrochemical technology was used to treat synthetic wastewater containing Methyl Red (MR) and Blue Novacron (BN) by anodic oxidation using anodes platinum (Pt) and real samples of textile effluents using DDB anodes and platinum (Pt). The removal of color from the galvanostatic electrolysis of synthetic wastewater MR and BN, and the actual sample has been observed under different conditions (different current densities and temperature variation). The investigation of these parameters was performed in order to establish the best conditions for removal of color and chemical oxygen demand (BOD). According to the results obtained in this study, the electrochemical oxidation processes suitable for the degradation process of color and COD in wastewater containing such textile dyes, because the electrocatalytic properties of Pt and BDD anodes consumption energy during the electrochemical oxidation of synthetic solutions AN and MR and real sample, mainly depend on the operating parameters of operation, for example, the synthetic sample of MR, energy consumption rose from 42,00kWhm-3 in 40 mAcm-2 and 25 C to 17,50 kWhm-3 in 40mAcm-2 and 40 C, from the BN went 17,83 kWhm-3 in 40mAcm and 40?C to 14,04 kWhm- 3 in 40mAcm-2 and 40 C (data estimated by the volume of treated effluent). These results clearly indicate the applicability of electrochemical treatment for removing dyes from synthetic solutions and real industrial effluents / Neste trabalho, a tecnologia eletroqu?mica foi utilizada no tratamento de efluentes sint?ticos, contendo Vermelho de Metila (VM) e Azul de Novacron (AN), atrav?s da oxida??o an?dica utilizando ?nodos de Ti recoberto com platina (Ti/Pt). Ap?s isso, a fim de verificar a aplicabilidade do tratamento eletroqu?mico, amostras reais de efluentes t?xteis utilizando ?nodos de DDB e platina (Ti/Pt) foram tratadas eletroquimicamente visando a elimina??o completa dos corantes dissolvidos. A remo??o da cor a partir da eletr?lise galvanost?tica dos efluentes sint?ticos de VM e AN, e da amostra real tem sido observada em diferentes condi??es operacionais (diferentes densidades de corrente e varia??o da temperatura). A investiga??o destes par?metros foi realizada com o objetivo de estabelecer as melhores condi??es para remo??o da cor e da Demanda Qu?mica de Oxig?nio (DQO). De acordo com os resultados obtidos na realiza??o deste trabalho, o processo de oxida??o eletroqu?mica ? adequado para o processo de elimina??o da cor e da redu??o da DQO em efluentes que contenham esses corantes t?xteis, gra?as as propriedades eletrocatal?ticas dos ?nodos de DDB e Pt. O consumo de energia durante a oxida??o eletroqu?mica das solu??es sint?ticas contendo VM e AN e da amostra real depende principalmente das condi??es experimentais usadas, por exemplo, para a amostra sint?tica de VM, o consumo energ?tico passou de 42,00 kWhm-3 em 40 mAcm-2 e 25?C para 17,50 kWhm-3 em 40 mAcm-2 e 40?C; no entanto, o consumo de energia na eletr?lise do AN passou de 17,83 kWhm-3 em 40 mAcm-2 e 25?C para 14,04 kWhm-3 em 40 mAcm-2 e 40?C (dados estimados por volume de efluente tratado). Estes resultados indicam claramente a aplicabilidade de tal m?todo na remo??o de corantes dissolvidos em efluentes sint?ticos ou reais

Les métaux rares, comme le niobium (Nb), le tantale (Ta), le tungstène (W) et l'étain (Sn), sont définis comme des «ressources stratégiques» ou des «matériaux critiques». Dans cette étude, nous prenons les gisements de Nb de Huangshan et de Ta de Songshugang dans le complexe de Lingshan, province de Jiangxi, en Chine du Sud, comme exemples. Les roches de ce gisement sont classées en deux catégories en fonction de la présence de micas riches en Nb et de la quantité de columbite-tantalites: granites à grain moyen avec des micas riches en Nb et sans columbite-tantalites, et granites à grain fin et pegmatites riches en columbite-tantalites. Ces columbite-tantalites sont riches en Nb et pauvres en Mn, les classant comme columbite. Ces columbites ont des zonations complexes liées à des processus répétitifs. Notre travail indique plutôt que la formation de tels minéraux est liée à des processus de mélanges multiples avec au moins deux types de magmas. Les granites à grain moyen dans la suite Huangshan sont différents des autres granites du complexe de Lingshan par la composition de leurs micas: Li-annite (granite MA) et "protolithionite" (granite MP). Ils sont caractérisés par des teneurs Nb élevées (moyenne de 144 ppm en MP et 158 ppm en MA) et des rapports Nb/Ta très élevés (moyenne 15,3 en MP et 31,2 en MA). Le niobium est principalement hébergé dans les micas, avec une teneur moyenne en Nb de 1347 ppm dans les Li annites, et 884 ppm dans le «protolithionite», concentrations encore jamais mesurées dans les micas d’origine magmatique. Avec un contenu estimé à ~80 kt Nb, les granites de Huangshan représentent un nouveau style potentiel de ressource de Nb. Le granite à albite de Songshugang est localisé dans l'ouest du complexe de Lingshan et est enrichi en Ta. Le granite de Songshugang n’affleure pas et est se trouve sous des couches de granites à feldspath K-topaze, de greisens et de pegmatite. Tous les granites et pegmatites sont fortement peralumineux. Les minéraux de columbite-tantalites, de zircons et de cassitérites sont constants pour chaque type de roches et présentent les mêmes textures bi-phasées. Les caractéristiques pétrographiques indiquent que le stade précoce de columbite et de zircon ont été formés dans un environnement strictement magmatique. Le stade postérieur de ces minéraux a été influencé par des circulations fluides à la transition magmatique-hydrothermale. Les micas montrent également une texture en deux étapes, avec une grande quantité de d’inclusions de columbite-tantalites. L'enrichissement en Rb dans les bordures (Znw-II) est le résultat d’un fractionnement magmatique, comme démontré par la diminution de la teneur en Nb (16,3-108 ppm comparé avec 109-313 ppm pour le coeur). Cependant, les teneurs faibles et invariables du Ta, W et Sn démontrent que le magma résiduel n'a eu aucune influence sur les processus post-magmatiques postérieurs, contrairement aux minéraux de columbite-tantalites. Enfin, les datations U-Pb in-situ sur zircons et columbite-tantalites démontrent que les granites de Huangshan et de Songshugang se sont mis en place vers 130 Ma durant l’épisode tardi-Yanshanien (Crétacé), au même moment que l’ensemble des roches magmatiques formant le complexe de Lingshan. Ce résultat indique que cette période géologique est d’intérêt pour la formation de ressources en Nb-Ta, définissant une nouvelle période géologique prospective pour ces ressources / Rare metals, including niobium (Nb), tantalum (Ta), tungsten (W) and tin (Sn), are defined as “strategic resources” or “critical materials”. For this work, we studied the Huangshan Nb deposit and Songshugang Ta deposit, in the Lingshan complex, Jiangxi Province, South China, as examples. The rocks from Huangshan granite are classified in two categories based on the occurrence of Nb-rich mica and the amount of columbite-tantalites minerals: medium-grained granites with Nb-rich mica and devoided of columbite-tantalites and fine-grained granites and pegmatites rich in columbite-tantalite minerals. Columbite-tantalite minerals are classified as columbite-(Fe), and characterized by complex zonings with various “go and back” processes, indicating that their formation is linked to multi-mixing processes of two different magma sources. The medium-grained granites in the Huangshan suite differed from the other granites of the Lingshan complex by their mica compositions: lithian annite (MA granite) and “protolithionite” (MP granite). They are characterized by elevated Nb contents (average 144 ppm in MP and 158 ppm in MA) and very high Nb/Ta ratios (average 15.3 in MP and 31.2 in MA). Niobium is mainly hosted in the micas, with an average Nb content of 1,347 ppm in the lithian annite, and 884 ppm in the “protolithionite”. Such contents are the highest ever reported in magmatic-related micas. With an estimated content of ~80 kt Nb, the Huangshan granites represent a new style of potential Nb resource. The Songshugang albite granite is found in the west of Lingshan complex and is specifically enriched in Ta. The major Songshugang albite granite is buried and covered by layers of K-feldspar granite, greisen and pegmatite. All the granites are strongly peraluminous. The compositions of columbite-tantalite minerals, the zircons and cassiterites are constant and display a similar two-stage texture. Petrographic features indicate that the early-stage columbite and zircon were formed in magmatic environment, whereas the later-stage of rare-element minerals were influenced by fluid fluxes at the magmatic-hydrothermal transitional stage. Micas also show a two-stage texture. The Rb-enrichment in the margin of the zinnwaldite is the result of magmatic fractionation, as also demonstrated by the decrease of Nb contents (16.3-108 ppm compare with core of 109-313 ppm). The invariable low contents of Ta, W and Sn demonstrate that the residual melt has no influence on later post-magmatic stages, contrary to the columbite minerals. Finally, in-situ U-Pb dating of zircon and columbite-tantalite by SIMS and LA-ICP-MS indicates that both Huangshan and Songshugang granites were emplaced at ca. 130 Ma during Later Yanshanian (or Cretaceous) and contemporary with the formation of the Lingshan complex. This result indicates that the Later Yanshanian is a prospective geological period for Nb-Ta deposits, and this result enlarges the time frame of rare-metal mineralization.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-19T13:34:45Z No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-20T10:58:08Z (GMT) No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-20T10:58:09Z (GMT). No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-20 / L-Dopa ? convertida em dopamina no c?rebro e continua a ser a droga mais amplamente prescrita no tratamento da doen?a de Parkinson. Um sens?vel e seletivo sensor foi desenvolvido para a determina??o voltam?trica de L-Dopa em formula??es farmac?uticas usando um Eletrodo de Grafite Pirol?tico de Plano Basal (EGPPB) modificado com cloro(piridil)bis(dimetilglioximato) de cobalto (III) (Co(DMG)2ClPy), um modelo sint?tico da vitamina B12, adsorvido em Nanotubos de Carbono de Paredes M?ltiplas (NCPM), o qual foi denominado EGPPB/NCPM/Co(DMG)2ClPy. Microscopia Eletr?nica de Varredura e Espectroscopia no Infravermelho por Transformada de Fourier foram utilizadas para caracterizar os materiais. A oxida??o de L-Dopa utilizando o EGPPB/NCPM/Co(DMG)2ClPy foi investigada por Voltametria C?clica, Amperometria, Voltametria de Pulso Diferencial e Voltametria de Onda Quadrada. O eletrodo modificado apresentou uma excelente atividade catal?tica para a oxida??o de L-Dopa em 180 mV vs. Ag/AgCl. Os par?metros que influenciam a resposta do eletrodo foram investigados. As condi??es ?timas foram encontradas para o eletrodo modificado com 100 ?mol L-1 de Co(DMG)2ClPy, 2 mg mL-1 de NCPM, em solu??o tamp?o fosfato na concentra??o de 0,2 mol L-1 (pH 7,4). O n?mero de el?trons envolvidos na oxida??o de L-Dopa foi igual a dois. As correntes de pico voltam?tricas apresentaram uma resposta linear para a concentra??o de L-Dopa no intervalo de 3 a 100 ?mol L-1 para n = 12 (R = 0,9992), com sensibilidade, limite de detec??o e limite de quantifica??o iguais a 4,43 ?A cm-2/?mol L-1, 0,86 e 2,87 ?mol L-1, respectivamente. O Desvio Padr?o Relativo para 10 determina??es de solu??o 50 ?mol L-1 de L-Dopa foi de 1,63%. Os resultados obtidos para a determina??o de L-Dopa em formula??es farmac?uticas est?o de acordo com o m?todo de compara??o oficial. Estudos de adi??o e recupera??o do analito foram realizados para avaliar a exatid?o do m?todo e verificou-se que foi poss?vel uma porcentagem de recupera??o entre 99,4 e 101,5% para a L-Dopa. Portanto, o sensor desenvolvido pode ser aplicado com sucesso para a determina??o do referido f?rmaco em medicamentos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011. / ABSTRACT L-Dopa is converted to dopamine in the brain and remains the most widely prescribed drug in the treatment of Parkinson's disease. A sensitive and selective method was developed for the voltammetric determination of L-Dopa in pharmaceutical formulations using a Basal Plane Pyrolytic Graphite Electrode (BPPGE) modified with chloro(pyridil)bis(dimethylglyoximato)cobalt(III) (Co(DMG)2ClPy), synthetic model of vitamin B12, absorbed on Multi-walled Carbon Nanotube (MWCNT), denominated MWCNT/Co(DMG)2ClPy/BPPGE. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were used to characterize the materials. The oxidation of L-Dopa using the MWCNT/Co(DMG)2ClPy/BPPGE was investigated by Cyclic Voltammetry, Amperometry, Differential Pulse Voltammetry and Square Wave Voltammetry. The modified electrode showed an excellent catalytic activity for L-Dopa oxidation at 180 mV vs. Ag/AgCl. The parameters that influence on the electrode response were investigated. The optimum conditions were found to the modified electrode with 100 ?mol L-1 Co(DMG)2ClPy, 2 mg mL-1 MWCNT, in 0.2 mol L-1 phosphate buffer solution (pH 7.4). The number of electrons involved in L-Dopa oxidation was two. Voltammetric peak currents showed a linear response for L-Dopa concentration in the range from 3 up to 100 ?mol L-1 for n = 12 (R = 0.9992), with a sensitivity, detection limit and quantification limit of 4.43 ?A cm-2/?mol L-1, 0.86 and 2.87 ?mol L-1, respectively. The Relative Standard Deviation for 10 determinations of 50 ?mol L-1 L-Dopa was 1.63%. The results obtained for L-Dopa determination in pharmaceutical formulations was in accordance with the official method of comparison. Studies of addition and recovery of the analyte were carried out to evaluate the error of the method and was verified a recovery percentage between 99.4 and 101.5% for L-Dopa. Therefore the sensor developed can be applied successfully to the determination of this drug in pharmaceuticals formulations.