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1
Al-Mugrabi, M. A. "Optimisation of instrumental neutron activation analysis." Thesis, University of Surrey, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377262.
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Farooqi, Asad Saeed. "Nuclear activation techniques and methods of elemental concentration determination in bioenvironmental studies." Thesis, University of Surrey, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280334.
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Zhang, Li 1969. "Coded aperture imaging for fast neautron activation analysis." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41018.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 107-111).
by Li Zhang.
M.S.
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Kipler-Koch, Debra Ann. "Provenance determination of Bronze Age pottery using neutron activation analysis /." Online version of thesis, 1989. http://hdl.handle.net/1850/11432.
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Blaylock, Dwayne Patrick. "Activation products in the biological shield of the Georgia Tech Research Reactor." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/19431.
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Liddy, D. J. "A study of Roman amphoras from North Africa by neutron activation analysis." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355911.
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Ames, Michael Richard. "Development and application of a methodology for measuring atmospheric mercury by instrumental neutron activation analysis." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36020.
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Inyang, Otu Effiong. "Development of a prompt-gamma, neutron-activation analysis facility at the Texas A&M University Nuclear Science Center." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2980.
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De, Chiara Alessia. "Molecular analysis of the prosurvival effect of cytosolic Proliferating Cell Nuclear Antigen (PCNA) in neutrophils." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05S002.
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Le polynucléaire neutrophile (PMN), cellule clé de l’immunité innée, est la première cellule à être recrutée sur le site inflammatoire. Après avoir détruit l’agent pathogène, il entre en apoptose puis est éliminé par les macrophages pour éviter le déversement de son contenu lytique, dangereux pour l’environnement. La régulation de la balance survie/apoptose du neutrophile est donc une étape cruciale de la résolution de l’inflammation. Notre laboratoire a mis en évidence la présence du Proliferating Cell Nuclear Antigen (PCNA) dans le neutrophile mature. PCNA est exprimé dans le noyau des cellules proliférantes, où il est impliqué dans la réplication/réparation de l’ADN et dans le contrôle du cycle cellulaire. PCNA est une protéine trimérique conservée au cours de l’évolution dépourvue d’activité enzymatique. En effet, PCNA constitue une “plateforme” qui interagit avec différents partenaires protéiques et orchestre leurs fonctions. De plus, pour assurer sa fonction, PCNA doit être obligatoirement sous forme trimérique. Dans le neutrophile mature, il a été démontré que PCNA avait une localisation exclusivement cytosolique et qu’il contrôlait spécifiquement la survie du neutrophile. La translocation de PCNA du noyau au cytosol a lieu pendant la différenciation granulocytaire. Elle est dépendante d'une séquence d'export nucléaire (NES) accessible et fonctionnelle que lorsque PCNA est monomérique. Le but de ma thèse a été d’étudier la plateforme de PCNA dans le cytosol du neutrophile afin d'identifier les protéines associées à PCNA afin de comprendre sa fonction dans les neutrophiles. Nous avons montré la présence de la forme monomérique et de la forme trimérique de PCNA dans le cytosol du neutrophile mature. Nous avons démontré une activité anti-apoptotique de la forme monomérique dans des cellules PLB985 différenciées en neutrophiles. De plus, nous avons identifié des peptides exposés sur la surface monomérique de PCNA qui sont utilisé comme des compétiteurs pour déplacer les interactions entre PCNA et ses partenaires dans le cytosol des neutrophiles. Ces peptides modulent la survie des neutrophiles. Grâce à des analyses de Spectrométrie de Masse, nous avons identifié des nouveaux partenaires de PCNA dans le cytosol du neutrophile impliqués dans plusieurs voies métaboliques. Cela suggère que PCNA régule la survie du neutrophile en interagissant avec différents protéines cytosoliques. Parmi les partenaires identifiés, nous avons trouvé les sous-unités cytosoliques de la NADPH oxydase, enzyme responsable de la production de formes réactives de l’oxygène, à la base de l’activité microbicide du neutrophile. Nous avons montré en particulier l’interaction entre p47phox et PCNA. Nous avons enfin étudié l’implication fonctionnelle de l’interaction de PCNA avec la NADPH oxydase dans des cellules PLB985 et également dans des neutrophiles humains. L’ensemble des résultats suggère que PCNA cytoplasmique maintient le neutrophile dans un état de repos, et aide l’assemblage de la NADPH oxydase lors de son activation. Le réseau protéique associé à PCNA régule l’activité et la survie du neutrophile en modulant différentes voies de signalisationPolymorphonuclear neutrophils (PMN), key cells of innate immunity are the first cell recruited to the inflammatory site. After destroying the pathogen, neutrophils undergo apoptosis and are cleared by macrophages to prevent the spillage of their lytic content that is dangerous for the environment. The regulation of the survival/apoptosis balance of neutrophil is a crucial step in the inflammation resolution. Our laboratory has shown the presence of Proliferating Cell Nuclear Antigen (PCNA) in mature neutrophils. PCNA is expressed in the nucleus of proliferating cells, where it is involved in DNA replication/repair and in cell cycle control. PCNA is a trimeric protein conserved during evolution and deprived of enzymatic activity. Indeed, PCNA is a “platform” that interacts with different partner proteins and orchestrates their functions. Furthermore, PCNA must be in trimeric form to play its role. In mature neutrophils, PCNA has an exclusively cytosolic localization where it specifically controls their survival. The PCNA translocation from nucleus to the cytosol happened during the granulocytic differentiation. This nuclear-to-cytosol relocalisation is dependent on a nuclear export sequence (NES), which is accessible and functional when PCNA is monomeric. The aim of my thesis was to study the PCNA platform in the neutrophil cytosol to identify the proteins associated with PCNA in order to understand its function in neutrophils. We have shown the expression of monomeric and trimeric forms of PCNA in the cytosol of mature neutrophils. We have demonstrated the anti-apoptotic activity of the monomeric form in PLB985 cells differentiated in neutrophils. Moreover, we have identified the surface-exposed peptides from the monomeric PCNA which are used as competitors of interactions between PCNA and its partner in the cytosol of neutrophils. These peptides modulate neutrophils survival. Thanks to the analysis of Mass Spectrometry, we have identified new partners of PCNA in the neutrophil cytosol involved in several metabolic pathways. This suggests that PCNA regulates neutrophil survival by interacting with different cytosolic proteins. Among the identified partners, we have found the cytosolic subunits of the NADPH oxidase, the enzyme responsible of the reactive oxygen species production, at the base of the neutrophil microbicidal activity. We have shown especially the interaction between p47phox and PCNA. Finally, we have investigated the functional implication of the interaction of PCNA with the NADPH oxidase in PLB985 cells and also in human neutrophils. Taken altogether, results suggest that the cytosolic PCNA maintains the resting state of neutrophils, and it helps the assembly of the NADPH oxidase when activated. The protein network associated with PCNA regulates the activity and the survival of neutrophil by modulating several pathways
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Miller, Dean Allan. "Monte Carlo dosimetry and activation calculation for a proposed fusion device : MCNP analysis of aAlcator C-MOD." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15123.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaf 109.
by Dean Allan Miller.
M.S.
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Khan, Mohammad Saeed. "Differences in the uptake of caesium by plants studied by neutron activation analysis." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357005.
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Wu, Sherry C. (Sherry Chi-Yung). "Methodology for capturing and measuring dissolved mercury in natural waters using ion exchangers and instrumental neutron activation analysis." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40217.
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BAPTISTA, TATYANA S. "Valores de referencia de elementos em sangue de cavalos da raca crioula via metodologia nuclear." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9587.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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OLIVEIRA, LAURA C. de. "Desenvolvimento de metodologia nuclear para analises clinicas." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11086.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Franco, Milton Batista. "Levantamento de parametros nucleares do reator TRIGA MARK I IPR RI com configuração concentrica visando a aplicação da tecnica de ativação neutronica Ko." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266186.
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Orientador: Elias Basile TambourgiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Este trabalho teve como objetivo determinar os parâmetros f, a, índice espectral e temperatura de nêutrons na mesa (parada e girando) e no tubo central do REATOR IPR-R1, visando a aplicação da técnica de ativação neutrônica paramétrica ko. É um método monopadrão de análise química por ativação neutrônica de aplicação bastante geral que elimina preparações tediosas de curvas de padrões, com capacidade analítica quantitativa multielementar e com uma exatidão comparável ao método relativo clássico¿Observação: O resumo, na íntegra poderá ser visualizado no texto completo da tese digital
Abstract: This research intended to determine the nuclear parameters a, f, spectral index and neutron temperature in several irradiations positions of the TRIGA MARK I IPR-R1 reactor, for use on the parametric method ko in the CDTN. Ko is a monostandard method of neutron activation analysis. It is, on the whole, experimentally simple, flexible and an important tool for accurate and convenient standardization in instrumental multi-element analysis...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Doutorado
Sistemas de Processos Quimicos e Informatica
Doutor em Engenharia Química
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Sullivan, Daniel D. "Neutron activation analysis and chemical inference for the identification of Buena Vista ceramics." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3699.
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Instrumental Neutron Activation Analysis was used for this study of stonewares collected from the site of the Buena Vista/Oregon Pottery Company (1866-1890).
The results show significant chemical signatures in the samples tested. Thorium/ytterbium and thorium/chromium ratios within their respective ranges of variation demonstrate a relative conformity among all samples of Buena Vista ceramics.
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Arnold, Michelle. "Development of an accelerator based system for In vivo neutron activation analysis measurements of manganese in humans /." *McMaster only, 2000.
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OLIVEIRA, LAURA C. de. "Estudo da distribuição de íons e metais em sangue via metodologia nuclear." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11609.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Stratton, Charles D. "Evaluation of Short Term versus Long Term Air Quality Sampling Methods Using X-ray Fluorescence and Neutron Activation Analysis." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1299180519.
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Baptista, Tatyana Spinosa. "Valores de referência de elementos em sangue de cavalos da Raça Crioula via metodologia nuclear." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-29082011-101429/.
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No presente estudo valores de referência para Br (0,0008 - 0,0056 gL-1), Ca (0,089 - 0,369 gL-1), Cl (2,10 - 3,26 gL-1), Fe (0,381 - 0,689 gL-1), I (0,00018 - 0,00266 gL-1), K (1,14 - 2,74 gL-1), Mg (0,030 - 0,074 gL-1), Na (1,36 - 2,80 gL-1), P (<1,99 gL-1), S (0,99 - 2,79 gL-1) e Zn (0,0012 - 0,0048 gL-1) bem como a matriz de correlação em sangue de eqüinos da Raça Crioula foram determinados utilizando metodologia nuclear (técnica de Análise por Ativação com Nêutrons). Estes dados permitiram identificar alterações fisiológicas relacionadas ao gênero e regime de exercício em que se enquadram estes animais (produção de soros hiperimunes no Instituto Butantan, São Paulo, Brasil). Para realização dessas análises foram utilizados 20 cavalos adultos (8 machos e 12 fêmeas) sadios, na faixa etária de 1 a 3 anos e peso médio de 350 kg, mantidos na Fazenda São Joaquim do Instituto Butantan (São Paulo). Outro grupo recém imunizados, composto por 6 cavalos machos (mesmo peso e idade) foram também analisados. Estes dados auxiliaram na interpretação das funções fisiológicas desses elementos no sangue destes animais durante o processo de imunização para produção de soros.In this study the reference value for Br (0,0008 - 0,0056 gL-1), Ca (0,089 - 0,369 gL-1), Cl (2,10 - 3,26 gL-1), Fe (0,381 - 0,689 gL-1), I (0,00018 - 0,00266 gL-1), K (1,14 - 2,74 gL-1), Mg (0,030 - 0,074 gL-1), Na (1,36 - 2,80 gL-1), P (<1,99 gL-1), S (0,99 - 2,79 gL-1) and Zn (0,0012 - 0,0048 gL-1) as well as the correlation matrix in blood of Crioulo breed horses were determined using nuclear methodology (Neutron Activation Analysis Technique). These data allowed to identifying physiological alterations related to the sex and regime of exercise (hyperimmune sera production at Butantan Institute, São Paulo, Brasil). To perform these analyses was used 20 adult horses (8 males and 12 females), with average mass 350 kg, without clinical signs of disease, 1-3 years old, kept on pasture in São Joaquim Farm at Butantan Institute (São Paulo city). Other group just immunized, composed by 6 equines males (same age and weight), were also analyzed. These data are an important support to understand the physiological functions of these elements in blood during the process of sera production.
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Brockman, John Douglas. "Investigation of K₀ neutron activation analysis at MURR and investigation of the toenail as a biomonitor for Mg, Zn, Cu, Se and Hg." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/5890.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 13, 2007) Vita. Includes bibliographical references.
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Lai, Chao-Jen. "Relocation of a neutron capture prompt gamma-ray analysis facility at the University of Missouri Research Reactor and measurement of boron in various materials /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974649.
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Bertinato, Jesse. "Analysis of the Ku antigen-dependent activation of reporter genes in yeast and characterization of the nuclear import signals of Ku antigen." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6113.
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Ku antigen (Ku70/Ku80) is a heteromeric, DNA binding protein that has been implicated in DNA repair, V(D)J recombination, tumour suppression, growth, cell cycle control, telomere maintenance and the regulation of gene transcription. Ku is a DNA binding subunit of the DNA-dependent protein kinase and functions to recruit and stimulate the catalytic subunit at appropriate DNA target sites. I present the unexpected finding that expression of human Ku fused to an ectopic activation domain broadly activated reporter genes integrated into the yeast genome independent of the reporter gene, yeast minimal promoter and reporter gene integration site. Interestingly, expression of various Ku70 deletion mutants alone or in combination with Ku80 revealed that the regions of Ku identified to be required for activation share a striking resemblance to portions of Ku needed to bind DNA. Furthermore, a mutation in Ku70 that negates the Ku70-dependent activation property in yeast also disrupts the ability of Ku70 monomers to associate tightly with the nucleus in mammalian cells. Moreover, I demonstrate that human Ku80 cannot substitute for the yeast homologue (HDF2) to rescue the temperature sensitive phenotype of a yeast strain deficient in Ku80 but expression of a variant human Ku heterodimer partially rescues the phenotype. By contrast, the characteristic slow growth displayed by HDF2 deficient yeast at 30°C could not be rescued by expression of the same human Ku heterodimer. Also, I determined that Ku70 contains a bipartite nuclear localization signal between amino acids 539--556, while the core of the nuclear localization signal of Ku80 is a basic motif from 565--569. Each nuclear localization signal mediated the nuclear transfer of the individual Ku subunits and Ku heterodimer, while site directed mutagenesis of both nuclear localization signals resulted in a Ku heterodimer that was localized to the cytoplasm. Lastly, I show that mutations in Ku previously proposed to abrogate Ku70/Ku80 heterodimerization reduce the accumulation of Ku70 without affecting heterodimer formation in mammalian cells.
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Smith, Debbie A. "Analytical Methods for Toxic Metals and Proteins and Synthesis of Perovskites." Youngstown State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1289923061.
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Santos, Diogo Feliciano dos. "Caracterização dos campos neutrônicos obtidos por meio de armadilhas de nêutrons a partir da utilização de água pesada (D2O) no interior do núcleo do reator nuclear IPEN/MB-01." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-22052015-135739/.
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Os experimentos realizados e apresentados nesta dissertação resultaram na caracterização neutrônica de núcleos na configuração cilíndrica com 30 varetas combustíveis de diâmetro com um espaço, criado pela retirada de 16 varetas centrais, preenchido com água leve (H2O) ou água pesada (D2O) no reator nuclear de pesquisa IPEN/MB-01. Nestes núcleos, efetuou-se experimentos de correlação de canais nucleares, calibração de barras de controle e irradiação de detectores de ativação de diversos materiais em forma de folhas, cujas faixas energéticas de atuação abrangem grande parte do espectro de nêutrons do núcleo do reator, para a obtenção de parâmetros nucleares, como excessos de reatividade, reatividades totais, atividades saturadas por núcleo alvo, razões espectrais, razões de cádmio e fluxo de nêutrons multigrupo. Com a irradiação de fios de ativação de ouro na parte radial foram obtidas as formas espaciais dos fluxos de nêutrons térmicos e epitérmicos. Os resultados mostraram as características espectrais dessa nova configuração com o espaço das 16 varetas combustíveis preenchido com os dois materiais moderadores. No espaço com a água leve houve um aumento significativo de 294% do fluxo de nêutrons térmicos em comparação com a configuração padrão retangular de 28×26 varetas combustíveis. Com a água pesada aumentou-se a reatividade do sistema com ρ = (783 ± 54) pcm a mais de excesso de reatividade que na configuração com água leve. Os resultados calculados foram simulados nos códigos computacionais MCNP5, SANDBP e CITATION, onde se obtiveram resultados acurados e precisos para as atividades saturadas por núcleo alvo, as distribuições energéticas e espaciais dos fluxos de nêutrons da parte ativa e de parte do refletor e as comparações diretas das seções de choque entre as razões espectrais experimentais e calculadas.The experiments performed and presented in this thesis results in the neutronic characterization of the core with cylindrical configuration with 30 fuel rods diameter and a space, created by the removal of 16 central rods, filled with light water (H2O) or heavy water (D2O) in the IPEN/MB-01 nuclear research reactor. In these cores were performed experiments of nuclear channels correlation, control rod worth and irradiation of activation detectors of various materials in foils shapes, whose energy performances cover much of the reactor core neutron spectrum, to obtain nuclear parameters, such as, reactivity excesses, total reactivities, saturated activities per target nucleus, spectral ratios, cadmium ratios and multigroup neutron flux. Activation gold wires detectors were irradiated in radial part to obtain the spatial forms of thermal and epithermal neutron fluxes. The results show the spectral characteristics of this new configuration with the space of 16 fuel rods filled with the two moderator materials. In the space with light water there was a significant increase of 294% of the thermal neutron flux compared to standard rectangular configuration of 28×26 fuel rods. With heavy water the system reactivity was increased, more ρ = (783 ± 54) pcm in excess reactivity than in the light water configuration. The calculated results were simulated in computational codes MCNP5, SANDBP and CITATION, where accurate and precise results were obtained for saturated activities per target nucleus, the energy and spatial distributions of the neutron fluxes for the active part and part of the reflector and the direct comparisons of cross sections between the experimental and calculated spectral ratios.
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Turkoglu, Danyal J. "Evaluation of Prompt Gamma-ray Data and Nuclear Structure of Niobium-94 with Statistical Model Calculations." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417737555.
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Noyori, Amanda. "Estudo sobre determinação de alumínio em amostras ambientais pelo método de análise por ativação com nêutrons." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-07122017-113255/.
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As determinações de alumínio são de grande interesse devido à sua toxicidade e sua ampla distribuição no meio ambiente. Além disso as determinações deste elemento por métodos analíticos convencionais apresentam dificuldades devido aos problemas da contaminação da amostra. O método de análise por ativação com nêutrons (NAA) para determinação de Al possui vantagens de rapidez na análise e de alta sensibilidade. Entretanto, neste método ocorrem os problemas de reações nucleares de interferência de P e Si. O Al na NAA é determinado pela medida do 28Al formado na reação 27Al (n, γ) 28Al, o mesmo radioisótopo formado nas reações nucleares 31P (n, α) 28Al e 28Si (n, p) 28Al. O objetivo deste estudo foi determinar Al pela NAA em amostras ambientais, fazendo a correção das interferências usando fatores de correção e dispondo das concentrações de P e de Si das amostras. Neste estudo foram analisados os materiais de referência certificados (MRCs) e amostras de biomonitores (cascas de árvore e líquen). O procedimento experimental consistiu na irradiação curta de uma alíquota de amostra no reator IEA-R1 juntamente com o padrão de Al, seguida de espectrometria de raios gama. O P foi determinado pela medida da radiação beta do 32P usando um contador Geiger-Müller. O Si foi determinado por meio da irradiação com nêutrons epitérmicos e medida do 29Al formado na reação 29Si (n,p) 29Al. Os resultados da determinação de Al, P e Si nos MRCs apresentaram uma boa precisão e exatidão com |Z-score| ≤ 2. As concentrações de Al obtido nos biomonitores variaram de 253 a 15783 μg g-1 e no caso da determinação de P e Si as concentrações destes elementos variaram de 283 a 1946 μg g-1 e de 0,11 a 7,8 %, respectivamente. Nos biomonitores analisados, as taxas de contribuição de interferência de P e de Si na determinação de Al foram da ordem de 2,0 % e esta contribuição depende das relações entre as concentrações dos interferentes e a do Al na amostra. Os limites de detecção de Al na análise dos biomonitores foram inferiores às suas concentrações demonstrando que procedimento de NAA proposto pode ser aplicado na determinação de Al neste tipo de matriz.Aluminum determinations are of great interest since this element is toxic to humans and it is widely distributed in the environment. Besides, the determinations of this element by conventional analytical methods present difficulties due to sample contamination during the analyses. Neutron activation analysis (NAA) for Al determination presents advantages of fast analyses and of high sensitivity. However, NAA of Al does present problems of P and Si nuclear reaction interferences. Aluminum is determined by measuring 28Al, formed in the reaction 27Al (n, γ) 28Al, the same radioisotope formed in reactions 31P (n, α) 28Al and 28Si (n, p) 28Al. The purpose of this study was to determine Al in environmental samples by NAA correcting these interferences using correction factors, and determining P and Si concentrations in the samples. In this study, certified reference materials and biomonitor samples (tree barks and lichen) were analyzed. Experimental procedure consisted of irradiating an aliquot of the sample at the IEA-R1 nuclear research reactor together with Al standard, followed by gamma ray spectrometry. Phosphorus was determined by measuring beta radiation of 32P using a Geiger-Müller counter. Silicon was determined by epithermal neutron activation analysis and measuring 29Al formed in the reaction 29Si (n, p)29Al. Results obtained in the determination of Al, P and Si in the certified reference materials showed good precision and accuracy with |Z-score| ≤ 2. Aluminum results in the biomonitor samples varied from to 253 to 15783 μg g-1. In the case of P its concentrations varied from 283 to 1946 μg g-1. Silicon determinations in biomonitors varied from 0.11 to 7.8 %. The interference contribution rates in the analyses of the biomonitor samples were of the order of 2.0 % and this contribution depends on the relation between concentrations of interfering elements and of Al in the sample. Detection limit values of Al in the biomonitor analyses were lower than their concentrations in the samples demonstrating that the proposed procedure of NAA can be applied in the Al determination in this kind of matrix.
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Eichin, Randy. "Messung und Analyse von neutroneninduzierten Aktivitäten in Materialien zukünftiger Kernfusionsreaktoren." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1102604350687-80098.
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The radioactivity induced by neutrons in the materials of future fusion devices represents a central topic of safety- and environmental-related investigations. For the design and operation of future fusion devices, like the International Experimental Thermonuclear Reactor ITER or power plants like DEMO, the activation performance of the materials during operation and after shut-down has to be simulated. The European Activation System (EASY), consisting of the inventory code FISPACT and the activation library EAF, is the world wide reference system for these calculations. The activation of the fusion reactor materials, as well as the EASY system have to be tested experimentally. In the present work several samples of materials from the European fusion technology program were irradiated in neutron fields of DT neutron generators at TU Dresden and at Sergiev Posad near Moscow. The radioactivity following irradiation was determined several times during decay by ?×-spectroscopy. The results are analysed with EASY and ratios of the calculated-to-experimental activation (C/E) are determined, to find limits for the experimental validation of EASY. For the future improvement of EASY integral cross sections are obtained from these C/E and discussed in connection with the EAF data, energy differential measurements from the EXFOR System of the International Atomic Energy Agency (IAEA), other energy integral measurements and evaluated data from libraries in the JANIS system of the Nuclear Energy Agency (NEA). The investigated materials of the present work are Tungsten, Yttrium, CuCrZr and Lead. Tungsten is the preferred material for the divertor plates of fusion devices an a constituent of reduced activation structural materials. Yttrium is used in the ODS steels, which are candidate materials for the first wall and blanket structure of. The characteristic feature of ODS steels is to introduce Y2O3 oxide particles into structural materials like EUROFER to improve the high-temperature strength and to maintain superior radiation resistance. CuCrZr alloys are used as a heat sink in the first wall of the blanket and in the divertor. The CuCrZr alloys contain impurities in consequence of the production technology, which can have an influence on the activation performance and thus have to be known accurately. In this work the neutron activation analysis has proved to be an appropriate instrument to measure the amount of some special impurities. Lead acts as a neutron multiplier and coolant in breeding blanket concepts such as the European Test Blanket Modules (TBM) with liquid Pb-17Li. Due to some large discrepancies between the measured activities and those calculated with EASY for tungsten, these cross sections are analysed with recent models of the nuclear reaction mechanisms. The sensitivity of the obtained cross sections with respect to different reaction models and parameters is investigated and limits for new evaluations are obtained with respect to the experimental resultsDie von Neutronen induzierten Aktivitäten in den Materialien zukünftiger Fusionsreaktoren stellen einen zentralen Punkt in der Forschung zur Sicherheit und Umweltverträglichkeit der gesteuerten Kernfusion dar. Für die Konstruktion und den Betrieb von Fusionsreaktoren, wie den Internationalen Thermonuklearen Experimental-Reaktor ITER oder Demonstrationskraftwerke wie DEMO, werden Simulationsrechnungen zum Aktivierungsverhalten der Materialien während des Betriebs und nach Abschalten des Reaktor durchgeführt. Das European Activation System EASY, bestehend aus dem Inventarcode FISPACT und der Datenbibliothek EAF, ist dabei weltweit das Referenzinstrument für derartige Rechnungen. Sowohl das Programmpaket als auch das Aktivierungsverhalten der im Fusionsreaktor verwendeten Materialien müssen experimentell getestet werden. Im Rahmen dieser Arbeit wurden zu diesem Zweck Proben von Materialien aus dem europäischen Fusionstechnologieprogramm in Neutronenfeldern der DT-Neutronengeneratoren der TU Dresden, bzw. an SNEG-13 im russischen Sergiev Posad bestrahlt. Die entstehende Radioaktivität wurde im Anschluss an die Bestrahlung zu verschiedenen Abklingzeiten mittels Gammaspektroskopie bestimmt. Die gemessenen Aktivitäten individueller Nuklide werden mit EASY analysiert und die Verhältnisse von gemessener Aktivität zu berechneter (C/E) werden für die einzelnen Aktivitäten bestimmt. Damit werden die Grenzen für die experimentelle Bestätigung der EASY-Berechungen ermittelt. Zur zukünftigen Verbesserung von EASY werden aus den C/E experimentelle Eingruppenwirkungsquerschnitte ermittelt, die im Kontext der EAF-Daten, energiedifferentieller Messungen aus dem EXFOR System der International Atomic Energy Agency (IAEA), vorangegangener energieintegraler Experimente und eingeschätzter Bibliotheksdaten aus dem JANIS System der Nuclear Energy Agency (NEA) diskutiert werden. Bei den untersuchten Materialien handelt es sich um Wolfram, Yttrium, CuCrZr und Blei. Wolfram ist ein bevorzugtes Material für den Divertor des Fusionsreaktors und zudem Bestandteil gering aktivierbarer Strukturmaterialien. Yttrium wird als Zusatz in den so genannten ODS Stählen verwendet, die in der ersten Wand und im Blanket eingesetzt werden. Diese entstehen aus Strukturmaterialien wie dem europäischen EUROFER, die bereits früher auf ihr Aktivierungsverhalten untersucht wurden, durch Hinzufügen von Y2O3-Partikeln, wodurch sie bei höheren Temperaturen und Neutronenflüssen einsetzbar werden. CuCrZr wird als Wärmeleiter in der ersten Wand des Blankets und im Divertor eingesetzt. Als Legierung ist CuCrZr mit technologisch bedingten Verunreinigungen versetzt, die sich auf das Aktivierungsverhalten auswirken können und deshalb genau bekannt sein müssen. Die Neutronenaktivierung hat sich dabei im Rahmen dieser Arbeit ebenfalls als geeignetes Mittel erwiesen. Blei agiert als Neutronenmultiplikator und Kühlmittel in Brutblanketkonzepten wie dem europäischen Test Blanket Module (TBM) das flüssiges Pb-17Li verwendet. Infolge der deutlichen Diskrepanzen zwischen der experimentellen und der mit EASY berechneten Aktivitäten bei Wolfram wird eine Analyse der Wirkungsquerschnitte mit Hilfe aktueller Modelle zum Mechanismus von Kernreaktionen vorgenommen. Dabei wird die Sensitivität der ermittelten Wirkungsquerschnitte auf verschiedene Reaktionsmodelle und Parameter getestet und ein Rahmen für Neueinschätzungen der Daten unter Berücksichtigung experimenteller Ergebnisse ermittelt
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Freitas, Cíntia Helena de. "Participação de complexos de lantanídeos entre as fases de reservatório de petróleo." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2007. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=72.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTraçadores são utilizados na explotação de reservatórios de petróleo para fornecer informações que auxiliam na otimização das operações envolvidas. Esta utilização já é comumente praticada fora do Brasil, sendo os mais empregados os radioativos, que apresentam sobre os compostos químicos as vantagens da simplicidade e sensibilidade de detecção e do custo. Uma possibilidade interessante é representada pelos traçadores ativáveis, que podem ser introduzidos no sistema a estudar no estado inativo e serem posteriormente amostrados e dosados por Ativação Neutrônica. Para esta aplicação os elementos da série dos lantanídeos foram testados, visto que estes oferecem características nucleares adequadas para análise. Os traçadores eficientes serão aqueles que não se atrasem ou se percam por interação com as rochas e/ou fluidos não aquosos presentes no reservatório, ou seja, que possuam elevada solubilidade em fase aquosa, coeficientes de partição nulos com a fase orgânica e que não sejam adsorvidos nas elevadas superfícies específicas disponíveis nas formações microporosas das quais desalojam as gotículas de petróleo. Deste modo foi necessário a complexação e quantificação do rendimento através da técnica de Cromatografia Líquida de Alta Eficiência (CLAE). As técnicas espectrométricas de Ressonância Magnética Nuclear (1H e 13C) e Infravermelho (IV) também foram empregadas para caracterização das espécies formadas. Foram realizados testes com o lantânio (La), o európio (Eu) e o disprósio (Dy) com os ligantes ácidos aminopolicarboxílicos (EDTA-2, DTPA) e tia-dicarboxílicos (C4H6SO4 , C7H12S2O4). Após a quantificação do rendimento e caracterização dos complexos de lantanídeos, concluiu-se que há complexação das espécies ligantes com os lantanídeos estudados. Os complexos obtidos em maior rendimento foram então submetidos a testes que simulam uma possível partição destes com a fase orgânica (Kp) e/ou sólida (Kd) do aqüífero, pela metodologia da Análise por Injeção em Fluxo (Flow Injection Analysis FIA) e por testes em um corpo de prova que simula as condições de fluxo em um reservatório de petróleo. O cálculo da partição determinada por Ativação Neutrônica e Espectrometria de Emissão Atômica com Plasma Indutivamente Acoplado (ICP/AES) apresentou um resultado nulo, o que torna possível a utilização dos respectivos complexos como traçadores ambientais em campo de petróleo. Os testes em corpo de prova evidenciaram uma excelente concordância entre o comportamento dos lantanídeos complexados e do traçador de referência (água tritiada). Um outro teste com a metaloporfirina (MnP) foi realizado como estágio prévio para o desenvolvimento de um novo traçador e os resultados positivos indicaram a viabilidade de sua futura utilização. Foram realizados os mesmos testes que para os complexos de lantanídeos, sendo que as determinações dos coeficientes de partição tanto com a fase orgânica (Kp) como com a fase sólida (Kd) foram efetuadas através da Espectrometria UV-Vis.
Tracers are used in the explotation of petroleum reservoirs in order to obtain information that help to optimize its operations. They are presently used on a routine basis in many countries, and the more often applied are the radiotracers, due to some advantages they have over the chemical tracers, such as the simplicity and the sensitivity of their detection besides the cost factor. One of the most conspicuous applications of tracers to reservoirs production activities refers to the evaluation of the secondary recovery techniques, due to their capability to inform about what happens in between the injection and production wells, differently from the other techniques that provide information only at discrete points. An option of interest for the normally required multiple tracer tests is afforded by activable tracers that can be fed to the system under study in the inactive state and have their samples collected at the exit irradiated and measured by Neutron Activation Analysis. Some of the elements of the lanthanide series that exhibit very high thermal neutron cross sections have been tested for this purpose. A properly performing tracer should not lag behind the liquid flow nor be lost through interactions with the rocks and non aqueous fluids inside the reservoir. This means that they must be quite hydrophilic, and have nearly null partition coefficients so that they are neither adsorbed on the internal surfaces of the rock pores nor migrate to the oil phase. Hence it has been necessary to form complexes of the lanthanide metals with appropriate ligands. Besides, to certify the product and to measure the achieved yield, these complexes had to be analyzed by High Performance Liquid Chromatography (HPLC), by 1H and 13C Nuclear Magnetic Resonance (NMR), and by Infrared Spectrometry (IR). The analyses have confirmed the complexation of the lanthanides processed by a previously selected methodology. Following that the performance of these lanthanide complexes as tracers have been tested in essays that simulate the possibility their partition in the oil phase (Kp) as well as their adsorption (Kd) in the solids inside the reservoir, by means of the Flow Injection Analysis (FIA) technique and of core tests, respectively. Tests have carried with lanthanum, europium and dysprosium, that have been complexed with aminopolicarboxylic acids (EDTA2-, DTPA), and with tiacarboxylic acids (C4H6SO4, C7H12S2O4). The measurement of partition, that has been carried by both Instrumental Neutron Activation Analysis (INAA) and Internal Couple Plasma/Atomic Emission Spectrometry (ICP/AES), evidenced null partition and this qualifies these complexes as oil field tracers. The core tests also displayed an excellent match between the lanthanide complexeds and the reference tracer used (tritiated water). On e other test using metal-porphyrin (MnP) has been performed as a previous stage for the development of a novel tracer and the positive results obtained have shown its feasibility for future applications. This complex has been submitted to the same tests performed with the lanthanides and the measurement of both the water phase and the oil, phase partition coefficients (Kp and Kd, respectively) has been carried using UV-Vis spectrometry.
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Mahajanam, Sudhakar P. V. "Application of hydrotalcites as corrosion-inhibiting pigments in organic coatings." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1123787459.
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Yadav, Nirbhay Narayan. "Quantification of trace metals in an adsorbent using proton induced x-ray emission." View thesis, 2005. http://handle.uws.edu.au:8081/1959.7/27789.
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Thesis (M.Sc.)(Hons) -- University of Western Sydney, 2005."A thesis presented to the University of Western Sydney in fulfilment of the requirements for the degree of Master of Science (Honours) Physics" Bibliography: leaves 101-108.
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Martins, Polyana Fabrícia Fernandes. "Desenvolvimento de traçadores ativáveis para aplicação em recuperação secundária de reservatórios de petróleo." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2005. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=8.
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Um campo interessante para aplicação de técnicas nucleares devido à complexidade dos problemas a serem estudados e importante devido ao forte impacto econômico e estratégico é a industria de petróleo. Pelas técnicas nucleares podem ser obtidas informações preciosas. A utilização de traçadores auxilia a caracterização de um reservatório de petróleo e permite que se tomem posteriormente decisões importantes para o processo de recuperação deste recurso natural.
O estudo é feito em uma malha envolvendo poços injetores e produtores, mas com um único traçador não é possível discriminar a contribuição de diferentes injetores para um determinado produtor. Devido a necessidade de se ter vários traçadores para serem usados na recuperação de poços de petróleo é proposto o desenvolvimento de traçadores ativáveis.
Foram escolhidos para serem usados como traçadores elementos do grupo dos terras raras lantânio (La) e európio (Eu) por apresentarem elevada seção de choque e facilidade de obtenção. Estes elementos foram complexados com quelantes orgânicos para diminuir o grau de perdas ou retardo do traçador em relação à fase aquosa. Esses quelantes são os ácidos aminopolicarboxílicos EDTA, DTPA e DOTA.
Para verificar se ocorreu a complexação foi feita análise por espectrometria no infravermelho. Com o resultado observou-se que houve a complexação em todos as amostras.
Para separar interferentes como sódio, cloro e bromo presentes na água de produção foi utilizado um processo de coprecipitação. O processo foi eficiente já que conseguiu precipitar os terras raras separando-os do sódio e bromo presentes na água.
Para verificar a partição do traçador com a fase oleosa e a fase aquosa foi realizado o teste de partição e em seguida calculado o coeficiente de partição ( Kao ) para todos os complexos (traçadores) em todos os testes.
Foi realizado um teste em corpo de prova para determinar os parâmetros de interação do traçador candidato com a rocha. Foram utilizados como traçador o trítio, La-EDTA e cloreto de európio. No caso do trítio, que serviu como referência para avaliação dos demais traçadores, não ocorreu retenção do traçador no interior dos poros do corpo de prova. Para o cloreto de európio e La-EDTA observou-se a ocorrência de adsorção nas superfícies internas dos poros do corpo de prova, seguida de dessorção.The application of nuclear techniques to the oil industry has both scientific and economical interest due to the complexity of the questions that have to be answered and to the strong economic and strategic impact of the fuel production activity. Valuable information can be obtained employing nuclear methods. In particular, they are instrumental in describing detailed flow patterns and other features of oil reservoirs that are unattainable to other methods. Besides, the information they provide substantiate more sound decisions on actions related to the recovery of this important natural resource. Tracer studies in oil fields are performed in a net of injection and producing wells. Thus, the use of only one tracer species would not discriminate the contributions of distinct injector wells to the response of a given production well. Hence, a multi-tracer experiment is required, and in to meet this purpose the use of activable tracers is proposed. As additional tracers lanthanum (La) and europium (Eu) were chosen from the rare earth series due to their large neutron cross sections and availability. In order to decrease losses to the oil phase and retardation of the tracer relatively to the aqueous phase, these elements were complexed with organic chelating ligands: the polyamino-carboxylic acids EDTA, DTPA , and DOTA. Infrared spectrometry was used to check complexation. Its results showed that complexation occurred in all the samples. A coprecipitation process was used to eliminate interfering agents such as sodium, chlorine, and bromine present in the water. The procedure proved to be efficient since it succeeded in precipitating the rare earths, thus separating them from the sodium and bromine dissolved in the water. In order to check the partition of the tracer between the aqueous and organic phases, tests were carried stirring the two phases together and measuring the tracer concentrations in the aqueous phase; the partition coefficient was ( Kao ) then calculated for all the combinations of the two lanthanides and three ligands. Continuous tests pumping the tracer through reservoir rock samples were also carried. Tritiated water was used as a reference tracer and the lanthanides employed were in form of La- EDTA and EuCl3. The last two were somewhat retarded due to adsorption followed by desorption in either the rock or oil phases
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SANTOS, DIOGO F. dos. "Caracterização dos campos neutrônicos obtidos por meio de armadilhas de nêutrons a partir da utilização de água pesada (D2O) no interior do núcleo do reator nuclear IPEN/MB-01." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23825.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-07-23T11:04:17Z
No. of bitstreams: 0Made available in DSpace on 2015-07-23T11:04:17Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Viana, Camila de Oliveira. "Uso de liquens como biomonitores na avaliação da contribuição de fontes poluidoras." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2010. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=120.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorOs níveis de poluição atmosférica, em geral, são avaliados pela medida direta dos principais poluentes através, por exemplo, da coleta de aerossóis e particulados em filtros de ar. Entretanto, essa metodologia apresenta dificuldades devido ao custo elevado de aquisição dos equipamentos coletores de ar, custos de manutenção e de coleta e também devido ao grande número de pontos de amostragens necessários para o monitoramento. Uma alternativa é aplicar o biomonitoramento, que é o acompanhamento de reações demonstradas por determinados seres vivos na presença de poluentes atmosféricos. Essa metodologia tem sido útil, pois fornece informações rápidas e seguras quanto aos efeitos antropogênicos no meio ambiente. A biomonitoração por liquens tem sido considerada uma ferramenta adequada de medidas diretas de contaminantes do ar, em comparação aos métodos convencionais. Este trabalho foi o primeiro em Belo Horizonte que, utilizando liquens epifíticos como biomonitores, indicou o nível de poluição atmosférica em termos de elementos químicos no centro da cidade, informação importante, já que Belo Horizonte é a 5 maior cidade brasileira em população, apresentando um fluxo intenso de veículos leves e pesados. O foco do trabalho foi o Parque Municipal Américo René Giannetti, localizado no hipercentro da capital, onde duas coletas foram realizadas amostrando liquens e solo. O Parque das Mangabeiras, unidade de conservação e localizado no limite leste da cidade, também teve essas matrizes analisadas. A concentração elementar foi determinada pela técnica de análise por ativação neutrônica, utilizando o reator nuclear de pesquisa TRIGA MARK I IPR-R1 do CDTN/CNEN. Os resultados foram avaliados pelo cálculo de fatores de enriquecimento, análises estatísticas e confecção de mapas de distribuição de elementos e indicaram que Al, Br, Cs, Cl, Fe, K, Mg, Mn, Na, Rb e Zn contribuem significantemente na composição da atmosfera local e que, como principais fontes poluidoras, destacam-se as emissões veiculares e re-suspensão do solo. A contribuição do solo está possivelmente relacionada aos empreendimentos minerários próximos à cidade. Ainda, há evidências de variação na disposição dos elementos químicos ao longo do talo liquênico, não relacionada ao tempo de exposição, mas possivelmente, ao tipo de elemento ou necessidade metabólica do líquen.
Atmospheric pollutant levels are generally analyzed by direct measure, using air collectors. There is, thus, an ever increasing interest in using indirect monitoring methods, such as analysis of bioacumulators organisms that can lead to different and additional diagnosis of the subject. Biomonitoring allows assessing environmental conditions using organisms that respond to levels of environmental pollutants to physiological or behavioral changes. Since the late 1860s, lichens have been increasingly used in air pollutant studies because of some of their biological characteristics, which make them very sensitive to alterations on the air composition. The use of lichens in biomonitoring of the atmospheric pollution levels is nowadays considered a rather adequate tool when compared to the conventional methods of direct measure of air contaminators. Belo Horizonte, the capital of the state of Minas Gerais, is located in the southeastern region of Brazil, having 2 million inhabitants and an intense flux of vehicles. Its surrounding areas are an important industrial center, concentrating many industries in several areas, such as mineral extractive industry, metallurgy, car plant and petrochemical industries. The air quality is usually evaluated analyzing the concentration of inhalable particulate matter (PM10), however, there are very few data about the citys level of atmospheric pollution concerning chemical elements. This work was the first in Belo Horizonte using lichens as biomonitors to indicate the level of atmospheric pollution in terms of chemical elements. The focus of the work was the Parque Municipal, a municipal park located downtown. Two samplings were done and samples of lichens and soil were taken from the Parque Municipal, and some from an ecological park located in the limits of the city (named Parque das Mangabeiras). The determination of the elementary concentration was set applying the analytical nuclear technique neutron activation analysis, k0-standardization method, using the research nuclear reactor TRIGA MARK I IPR-R1, located in Belo Horizonte. The results were evaluated applying the enrichment factors calculation, statistic analysis and production of distribution maps. Observing the results it was possible to conclude that the elements Al, Br, Cl, Fe, K, Mg, Mn, Na e Zn are expressive in the local atmospheric composition pointing out vehicular emissions and soil re-suspension as the main pollutant sources, the latter possibly related to the surrounding mining areas. The results also showed evidences of variation in the arrangement of chemical elements along the lichen thallus. This fact seems to be related to the type of elements or their metabolic needs.
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Queiroz, Paula Guimarães Moura. "Estudos da poluição do ar do município de Sete Lagoas, MG utilizando técnicas nucleares." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2006. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=53.
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NenhumaMetais tóxicos, tais como Ni, V, Zn, Cu, Cr, Mn e metalóides como o As e Se e seus compostos estão associados, principalmente, com a fração fina do material particulado presente nos aerossóis. Este fato é importante, em especial, do ponto de vista de saúde pública, pois esta é considerada a fração respirável de partículas que pode penetrar nas vias pulmonares e causar danos à região alveolar. Uma vez que na atmosfera as concentrações de metais traços, em geral, encontram-se em níveis muito baixos, a determinação da composição elementar dessas partículas requer o uso de técnicas analíticas apropriadas tais como o PIXE (Particle Induced X-Ray Emission), a análise por ativação neutrônica (AAN) e a espectrometria de fluorescência de raios X (FRX), entre outras. O principal objetivo do presente estudo foi a identificação das fontes geradoras do material particulado presente nos aerossóis atmosféricos do município de Sete Lagoas, um centro urbano de médio porte, onde se concentram diferentes tipos de indústrias. Para tanto, foram coletadas amostras de solo e de resíduos sólidos gerados pelas principais tipologias industriais da região, as quais incluem as indústrias de produção de ferro-gusa a carvão vegetal, a extração e/ou beneficiamento de calcário e a fabricação de concreto e produtos cerâmicos, bem como do material particulado total em suspensão (PTS) e do particulado inalável (PM10), ou seja, de partículas com diâmetro aerodinâmico menor que 10 mm. A medida da concentração de elementos traços presentes em cada uma das amostras foi realizada utilizando-se as técnicas de AAN e FRX e a determinação da sua composição mineralógica foi feita pela técnica de difração de raiosX. As análises por ativação neutrônica e de espectrometria de raios-X dos resíduos sólidos e de solo mostraram que os elementos químicos predominantes nestas amostras são o Al, Ba, Ca, Fe, K, Mg, Na, Ti e Zn. A análise da composição mineralógica indicou a presença marcante de silicatos (quartzo, microclina) carbonatos (calcita) e óxidos de ferro (hematita) nestas amostras. Durante o período de amostragem (11/01/2005 to 13/02/2005) foram observados altos níveis de concentração de material particulado. Os resultados de concentração massa para PTS indicaram que a qualidade do ar foi considerada Inadequada ou Má em 76% dos dias de amostragem. Para PM10 foi observado que em 53 % dos dias, a qualidade do ar foi considerada como Regular. A determinação da distribuição do tamanho das partículas dos aerossóis atmosféricos sugeriu que aproximadamente 80% das partículas possuem diâmetro aerodinâmico menor que 2,5 m. Os resultados da análise por ativação neutrônica mostraram que o Al, Fe, Cl, Cu, K, Mg e Na são os elementos químicos predominantes no PTS e o Na, Cu, Fe, Ba, Cl, Eu e Sm nas partículas inaláveis PM10. A análise da composição mineralógica pelo método de difração de raios-X indicou que a calcita (> 30%) e o quartzo (10 a 30%) são os minerais predominantes nas amostras de PTS e PM10. O modelo receptor utilizado foi a Análise de Componentes Principias, o qual identificou três perfis de fontes para PTS e quatro para o material PM10. Os resultados indicaram que as fontes poluidoras que mais contribuem na degradação da qualidade do ar na região são: a ressuspensão da poeira de solo, os processos industriais (produção de ferro-gusa e fabricação de concreto e produtos cerâmicos) e a queima combustíveis fósseis.
Toxic metals, such as Ni, V, Zn, Cu, Cr, Mn and metalloids as As and Se and their compositions are associated mainly with the smaller diameter particulates present in the atmospheric aerosols. This fact is important, principally, when it concerns public health, because this is considered the breathable fraction of particles that can penetrate deeply into the lungs and cause damage to the alveoli. Once in the atmosphere the concentrations of trace metals, in general, show very low levels, the determination of the elementary composition of those particles requires the use of appropriate analytical techniques such as Particle Induced X-Ray Emission (PIXE), neutron activation analysis (NAA) and of X-rays fluorescence spectrometry (XRF), among others. The main objective of this study was the identification of the generating sources of suspended particles present in the atmospheric aerosols of the municipal district of Sete Lagoas, a medium sized urban center, where different types of industries are found. In order to achieve that, soil samples and of solid wastes generated by the main industries of the area were collected. These include the industries of pig iron production that uses charcoal, the extraction and/or improvement of limestone and the fabrication of concrete and ceramic products, as well as the amount of total suspended particles (TSP) and of PM10 particles (those with an aerodynamic diameter smaller then 10 mm). The measurement of the concentration of trace elements present in each one of the samples was accomplished using the NAA and XRF techniques and the determination of its mineralogical composition was carried out through the technique of X- ray diffraction. The analyses by NAA and XRF of the solid wastes and of soil showed that the predominant chemical elements in these samples are Al, Ba, Ca, Fe, K, Mg, Na, Ti and Zn. The mineralogical composition analysis indicated the outstanding presence of silicate (quartz, microcline) carbonates (calcite) and oxides of iron (hematite) in these samples. High levels of particulate concentrations were measured during the sampling period (01/11/2005 to 02/13/2005). The mass concentration results for TPS indicated that in 76% of the days the air quality was considered Inadequate or Bad. The PM10 results showed that in 53% of the days the air quality was considered Reasonable. The determination of the size distribution of the particles presented in the atmospheric aerosols suggested that approximately 80% of the particles possess smaller aerodynamic diameter than 2.5 m. The results of the neutron activation analysis showed that Al, Fe, Cl, Cu, K, Mg and Na are the predominant chemical elements in the TPS and Na, Cu, Fe, Ba, Cl, Eu and Sm in PM10. The analysis of the mineralogical composition by the method of X-ray diffraction indicated that calcite (> 30%) and quartz (10 to 30%) are the most abundant minerals present in both, TPS and PM10. The receptor model used was the Main Component Analysis that identified three profiles of sources for TPS and four profiles for PM10. The results indicated that the pollutant sources that contribute the most for the degradation of the quality of the air in the region are: resuspended soil dust, industrial processes (pig iron production and the fabrication of concrete and ceramic products) and the burning of fossil fuels.
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CORREA, EDUARDO DE L. "Produção, caracterização e aplicação de nanopartículas de Gd2O3 e Er2O3 como radiossensibilizadores em feixes de Radioterapia." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27968.
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Nesse trabalho foram produzidas nanopartículas (NPs) de Gd2O3 e Er2O3 para aplicação como radiossensibilizadores em feixes de radioterapia. Elas foram sintetizadas no Laboratório de Interações Hiperfinas do IPEN pelo método da decomposição térmica e caracterizadas utilizando difração de raios-X, para verificar a estrutura cristalina, microscopia eletrônica de transmissão, para obter informações sobre forma, tamanho e distribuição de tamanho, análise por ativação neutrônica, por meio da qual foi possível determinar a pureza das amostras e calcular a concentração de gadolínio e érbio. Medições de magnetização e de espectroscopia de correlação angular γ-γ perturbada (PAC) foram realizadas a fim de estudar o comportamento magnético e a interação quadrupolar das partículas, respectivamente. Os resultados da caracterização mostram a formação de uma estrutura cristalina do tipo bixbyite, com aproximadamente 5 nm de diâmetro e estreita distribuição de tamanho, para as amostras pós-síntese. A determinação da massa de terra-rara em cada amostra foi importante para realizar a normalização nas medições de susceptibilidade magnética, tornando possível a visualização de um grande aumento na magnetização abaixo de 30 K, nas amostras pós-síntese, o que não é observado em partículas maiores, além de um aumento no momento magnético efetivo das NPs em relação aos respectivos bulks e uma mudança na temperatura de ordenamento antiferromagnético para o Er2O3. Os resultados da espectroscopia PAC evidenciam possíveis efeitos de superfície. A falta de uma frequência bem definida nas amostras de 5 nm indicam que a quantidade de 111In(111Cd) na superfície da partícula é maior do que no interior da mesma, fazendo com que a interação hiperfina do núcleo de prova com o host não seja evidente. Já a união da técnica de difração de raios-X com a espectroscopia PAC foi fundamental para o entendimento do dano causado às partículas pela irradiação com 60Co. Quanto às medições de radiossensibilização a dosimetria Fricke gel foi fundamental para a verificação de um fator de aumento de dose (DEF) de até 1,67 e 1,09 para NPs de Gd2O3 irradiadas com 60Co e 6MV, respectivamente. Nas mesmas condições, para as amostras de Er2O3, foram encontrados valores de DEF de até 1,37 e 1,06. Isso comprova os efeitos radiossensibilizadores dessas NPs. Os resultados alcançados nesse trabalho não apenas fornecem dados importantes para o estudo de NPs de terra-rara na área de física da matéria condensada como também uma base sólida para a aplicação desses elementos como radiossensibilizadores em feixes de radioterapia, possibilitando a utilização da imagem por ressonância magnética para localizar e obter a concentração dessas NPs dentro do paciente, aumentando assim a eficiência do tratamento do câncer.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Sheng, Fang. "X-ray crystallographic studies of SNAP190RcRd (Small Nuclear RNA Activating Protein) complex and E. Coli glycogen synthase." Diss., Connect to online resource - MSU authorized users, 2008.
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Bangs, Peter Lawrence. "Cloning, Characterization and Functional Analysis of TPR, an Oncogene-Activating Protein of the Nuclear Pore Complex: A Dissertation." eScholarship@UMMS, 1998. http://escholarship.umassmed.edu/gsbs_diss/146.
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A monoclonal antibody, mAb 203.37, raised against purified nuclear matrix proteins identified a single ~270 kDa protein that localized to the nuclear envelope. Double-label immunofluorescent microscopy using differential permeabilization protocols showed that this protein was present exclusively on the nucleoplasmic side of the nuclear envelope and that it co-localized with components of the nuclear pore complex. The nucleotide sequence of clones isolated using mAb 203.37 identified this protein as Tpr, a protein previously shown to be involved in oncogenic fusions with a number of protein kinases. Sequence analysis showed Tpr to be a 2348 amino acid protein with a predicted molecular weight of 265 kDa protein and a bipartite structure consisting of an ~1600 amino acid N-terminal domain that is almost entirely an α-helical coiled-coil followed by a highly acidic non-coiled carboxy-terminus. Ectopic expression of epitope-tagged Tpr constructs revealed two functional domains for Tpr: a nuclear pore complex binding domain and a nuclear localization sequence. The amino-terminus of Tpr, the portion of the protein shown to activate protein kinase oncogenes, did not localize to the nuclear pore complex indicating that the transforming activity of Tpr-protein kinase chimeras did not involve interactions with the nuclear pore complex. Ectopic expression of Tpr and a number of Tpr constructs resulted in the accumulation of poly (A)+ RNA in the nuclear interior but did not effect the import of a reporter protein into the nucleus indicating a role for Tpr in the export of mRNA from the nucleus.
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Speakman, Robert J. "Mimbres Pottery. Production and Distribution." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/123805.
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Mimbres-Mogollon people inhabited areas of southwestern New Mexico from approximately A.D. 200–1150, with settlements located primarily in the Gila, Mimbres, and Rio Grande Valleys and immediate adjacent areas. Among the most recognizable of Mimbres cultural traïts is the production of a white-slipped brown-paste ceramic decorated with bold, black, geometric designs. By about A.D. 1000, Mimbres pottery came to be more elaborately decorated with finely executed geomètric designs; in some cases, vessels were decorated with naturalistic motifs of animals, humans, plants, and anthropomorphized figures. This research project examines the production and distribution of Mimbres-Mogollon pottery using instrumental neutron activation analysis (INAA, NAA) to identify pottery production sites and the movement of pottery throughout the Mimbres and adjacent regions of the American Southwest.
Since publication of Gilman et al.’s (1994) seminal study of Mimbres pottery from the American Southwest using NAA, dozens of research projects involving the analyses of Mimbres-Mogollon and Jornada-Mogollon pottery have occurred. Projects have ranged in scale from small (<30) to large (e.g., 100–200 samples). These combined efforts have resulted to date in the analyses of thousands of Mimbres-Mogollon and Jornada-Mogollon ceramics and clays. Very little of this research has been formally published, and until now there has been no comprehensive analysis and interpretation that includes most/all extant NAA data.
In addition to hundreds of recent NAA analyses conducted for this project, most extant data generated for earlier Mimbres NAA projects are incorporated into this study. In total, the dataset includes more the 3,600 NAA analyses of pottery and clays obtained from several hundred archaeological sites in Arizona, New Mexico, Texas, and northern Mexico.
Research discussed herein provides—from a chemical perspective—the most accurate and comprehensive interpretation of Mimbres pottery production and distribution to date. Statistical analysis of the NAA dataset resulted in the identification of 35 distinct pottery groups. This finding is in contrast to most previous studies that only identified on average four to six compositional groups. Knowledge of the true group structure allows for a more accurate reconstruction of Mimbres pottery production and distribution and allows for examinations of temporal changes. Ultimately, this research will serve as a basis for archaeologists seeking to examine a broad range of topics related to Mimbres social organization and interaction, gender, and ideology.Els integrants de la cultura Mimbres-Mogollón habitaven zones del sud-oest de Nou Mèxic des d'aproximadament el 200-1150 dC, en assentaments ubicats principalment a les valls de Gila, Mimbres i de Río Grande i les zones adjacents immediates. Entre el trets culturals més característics de la societat Mimbres hi ha la producció d'una ceràmica de pasta marró i d’engalba blanca decorada amb audaços dissenys negres i figures geomètriques. Cap a l'any 1000 dC, la ceràmica Mimbres va arribar a ser més elaborada, decorada amb dissenys geomètrics finament executats. En alguns casos, les peces estaven decorades amb motius naturalistes d'animals, éssers humans, plantes i figures antropomorfiques. Aquest projecte d'investigació analitza la producció i distribució de la ceràmica Mimbres-Mogollon utilitzant l’anàlisi per activació neutrònica instrumental (INAA, NAA), tècnica d’anàlisi química emprada per identificar els llocs de producció de ceràmica i el moviment de la ceràmica a través de les regions de Mimbres i les regions adjacents del sud-oest dels Estats Units. Des de la publicació de Gilman et al. (1994) i el seu estudi acadèmic de la ceràmica Mimbres del sud-oest americà a partir de NAA, s'han produït desenes de projectes de recerca que impliquen l'anàlisi de ceràmiques i argiles de Mimbres-Mogollón i Jornada-Mogollon. Els projectes han oscil•lat en escala des de petits projectes (<30) a grans projectes (per exemple, de 100 a 200 mostres). Tots aquests esforços s'han traduït fins ara en l'anàlisi de milers de ceràmiques i argiles de Mimbres-Mogollón i Jornada-Mogollón. Molt poca d'aquesta investigació ha estat publicada oficialment, i fins ara no hi ha hagut una anàlisi exhaustiva i d’interpretació que inclogui la majoria o totes les dades de NAA existents. A més dels centenars de les darreres anàlisis realitzades per NAA per aquest projecte, les dades existents generades en anteriors projectes per NAA sobre ceràmiques de Mimbres s’han incorporat en aquest estudi. En total, el conjunt de dades inclou més de 3.600 anàlisis per NAA de ceràmica i argiles obtingudes a centenars de llocs arqueològics d’Arizona, de Nou Mèxic, de Texas i del nord de Mèxic. La investigació descrita aquí ofereix, des de la perspectiva de la química i l’arqueologia, la interpretació més precisa i completa a dia d’avui de la producció de la ceràmica Mimbres i de la seva distribució. L'anàlisi estadística del conjunt de dades de NAA ha resultat en la identificació de 35 grups diferents de ceràmica. Aquesta troballa contrasta amb la majoria dels estudis anteriors, els quals només van identificar de mitjana de quatre a sis grups composicionals. El coneixement de l'estructura dels grups químics permet una reconstrucció més precisa de la producció i distribució de la ceràmica de la cultura Mimbres, així com també proporciona una important eina per avaluar els canvis culturals i temporals. En última instància, aquesta investigació servirà com a base per als arqueòlegs que busquen examinar una àmplia gamma de temes relacionats amb l'organització cultural de Mimbres i la seva interacció social, el gènere i la ideologia.
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Cope, Zackary A., Kimberly N. Huggins, A. Brianna Sheppard, Daniel M. Noel, David S. Roane, and Russell W. Brown. "Neonatal Quinpirole Treatment Enhances Locomotor Activation and Dopamine Release in the Nucleus Accumbens Core in Response to Amphetamine Treatment in Adulthood." Digital Commons @ East Tennessee State University, 2010. https://doi.org/10.1002/syn.20729.
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Neonatal quinpirole treatment to rats produces long-term increases in D(2) receptor sensitivity that persists throughout the animal's lifetime, a phenomenon referred to as D(2) priming. Male and female Sprague-dawley rats were administered quinpirole (1 mg kg(-1)) or saline from postnatal days (P)1-11. At P60, all animals were given an injection of quinpirole (100 microg kg(-1)), and results showed that rats neonatally treated with quinpirole demonstrated enhanced yawning in response to quinprole, verifying D(2) receptor priming because yawning is a D(2) receptor mediated event. Beginning 1-3 days later, locomotor sensitization was tested through administration of d-amphetamine (1 mg kg(-1)) or saline every other day over 14 days, and horizontal activity and turning behavior were analyzed. Findings indicated that D(2)-priming enhanced horizontal activity in response to amphetamine in females compared to males at Days 1 and 4 of locomotor sensitization testing, and D(2)-priming enhanced turning in response to amphetamine. Seven to ten days after sensitization was complete, microdialysis of the NAcc core was performed using a cumulative dosing regimen of amphetamine (0.1-3.0 mg kg(-1)). D(2)-primed rats administered amphetamine demonstrated a 500% increase in accumbal DA overflow compared to control rats administered amphetamine. Additionally, amphetamine produced a significant increase in NE overflow compared to controls, but this was unaffected by D(2) priming. These results indicate that D(2) receptor priming as is produced by neonatal quinpirole treatment robustly enhances behavioral activation and accumbal DA overflow in response to amphetamine, which may underlie increases in psychostimulant use and abuse within the psychotic population where increased D(2) receptor sensitivity is a hallmark.
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Bouças, Janaína Gonçalves. "Aplicação de técnicas nucleares no estudo e avaliação da poluição do ar na Região Metropolitana de Belo Horizonte." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2009. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=112.
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Metais tóxicos, tais como Ni, V, Zn, Cu, Cr, Mn, e metalóides, como As e Se e seus compostos estão associados normalmente com as partículas de pequeno diâmetro presentes nos aerossóis atmosféricos. Esse fato é importante, principalmente, quando se refere à saúde pública, pois esta é considerada a fração respirável das partículas que podem penetrar profundamente dentro dos pulmões e causar danos aos alvéolos. A concentração de metais traço na atmosfera, em geral, mostram níveis muito baixos, a determinação da composição elementar destas partículas requer o uso de técnicas analíticas apropriadas tais como: Indução de Partículas por Emissão de Raios X (PIXE), Análise por Ativação Neutrônica (AAN) e Espectrometria por Fluorescência de Raios X, dentre outras. O principal objetivo deste estudo foi a identificação das fontes de emissão de partículas grossas (MP10) e finas (MP2.5) presentes nos aerossóis atmosféricos da Região Metropolitana de Belo Horizonte. A Análise por Ativação Neutrônica pelo método-k0 (k0-AAN) combinada com a Fluorescência de Raios X por Energia Dispersiva (ED-XFR) foram usadas para medir a concentração dos elementos traço presentes em cada amostra. Altos níveis de concentração de particulados especialmente MP2.5, foram medidos durante o período de amostragem. Em geral, a qualidade do ar variou de Razoável a Inadequada. O modelo receptor usado para a identificação das principais fontes emissoras foi a Análise dos Componentes Principais (APC). Os resultados mostraram que os principais elementos presentes no material particulado inalável (MP2.5 e MP10) foram Ag, Al, As, Au, Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mn, Na, , S, Sb, Sc, Si, Ti, W e Zn. Os resultados para análise multivariada mostram claramente quatro fontes poluidoras, sendo estas: emissões veiculares; re-suspensão de poeira de solo/asfalto; aerossóis secundários associados com a emissão de SO2; e emissões industriais associadas com a queima de combustíveis fósseis.Toxic metals, such as Ni, V, Zn, Cu, Cr, Mn and metalloids as As and Se and their compounds are mainly associated with the smaller diameter particulates present in the atmospheric aerosols. This fact is important, principally, when it concerns public health, because this is considered the breathable fraction of particles that can penetrate deeply into the lungs and cause damage to the alveoli. Once in the atmosphere the concentrations of trace metals, in general, show very low levels, thus the determination of the elementary composition of those particles requires the use of appropriate analytical techniques such as Particle Induced X-Ray Emission (PIXE), Neutron Activation Analysis (NAA) and X-Rays Fluorescence spectrometry (XRF), among others. The main objective of this study was the identification of the generating sources of gross (PM10) and fine (PM2.5) particles present in the atmospheric aerosols of the metropolitan region of Belo Horizonte. Neutron Activation Analyses by k0-method (k0-NAA) combined with Energy Dispersed by X-Ray Fluorescence was used to measurement of the concentration of trace elements present in each sample. High levels of particulate concentrations, especially PM2.5, were measured during the sampling period. In general, the air quality varied from Reasonable to Inadequate. The receptor model used to assist in the identification of the main emission sources was the Principal Components Analysis. The results showed that the main elements presents in particulate inhalable matter (PM2.5 and PM10) were Ag, Al, As, Au, Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mn, Na, , S, Sb, Sc, Si, Ti, W and Zn. The results for multi-variable analyses shown clearly four pollutant sources, these being: vehicular emissions; resuspended soil/asphalt powder; secondary aerosols associated with emission of SO2; and industrial emissions associated with fossil oil burning.
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Padro, Martinez Luz Teresa. "Towards an understanding of the cloud formation potential of carbonaceous aerosol laboratory and field studies /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31780.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Nenes, Athanasios; Committee Member: Huey, Greg; Committee Member: Meredith, Carson; Committee Member: Teja, Amyn; Committee Member: Weber, Rodney J. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Apone, Lynne Marie. "Analysis of TAF II Function in the Yeast Saccharomyces Cerevisiae." eScholarship@UMMS, 1998. https://escholarship.umassmed.edu/gsbs_diss/183.
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Transcription by RNA polymerase II is a highly regulated process requiring a number of general and promoter specific transcription factors. Although many of the factors involved in the transcription reaction are known, exactly how they function to stimulate or repress transcription is not well understood. Central to understanding gene regulation is understanding the mechanism by which promoter specific transcription activators (activators) stimulate transcription.
A group of factors called coactivators have been shown to be required for activator function in vitro. The best characterized coactivators to date are members of the TFIID complex. TFIID is a multisubunit complex composed of the TATA box binding protein (TBP) and 8-12 TBP associated factors (TAFIIs). Results from numerous in vitro experiments indicate that TAFIIs function by binding to activators and forming a bridge between the activator and the basal transcription machinery. In order to gain insight into the mechanism by which activators stimulate transcription, we chose to analyze the in vivo function of TAFIIs, their proposed targets.
Results from the genetic disruption of a number of TAFIIs in the yeast Saccharomyces cerevisiae showed that most are encoded by essential genes. In order to study their function, temperature-sensitive and conditional alleles were constructed. Cells depleted of individual TAFIIs by either of these two methods displayed no defect in global transcription activation. Inactivation of yTAFII17, however, resulted in a promoter specific defect. In addition, inactivation of yTAFII145, yTAFII90, or TSM1, resulted in an inability of cells to progress through the cell-cycle.
In an attempt to identify genes whose expression required yTAFII90, we performed subtractive hybridization on strains containing wild-type and temperature-sensitive alleles. Although this technique successfully identified genes differentially expressed in the two strains, it failed to identify genes whose expression required yTAFII90.
These results indicate that TAFIIs are not the obligatory targets of activators, and that other factors must provide this role in vivo. Furthermore, that many of TAFIIs are required for cell-cycle progression.
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CHIESA, DAVIDE. "Development and experimental validation of a Monte Carlo simulation model for the Triga Mark II reactor." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50064.
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In recent years, many computer codes, based on Monte Carlo methods or deterministic calculations, have been developed to separately analyze different aspects regarding nuclear reactors.
Nuclear reactors are very complex systems, which require an integrated analysis of all the variables which are intrinsically correlated: neutron fluxes, reaction rates, neutron moderation and absorption, thermal and power distributions, heat generation and transfer, criticality coefficients, fuel burnup, etc.
For this reason, one of the main challenges in the analysis of nuclear reactors is the coupling of neutronics and thermal-hydraulics simulation codes, with the purpose of achieving a good modeling and comprehension of the mechanisms which rule the transient phases and the dynamic behavior of the reactor. This is very important to guarantee the control of the chain reaction, for a safe operation of the reactor.
In developing simulation tools, benchmark analyses are needed to prove the reliability of the simulations. The experimental measurements conceived to be compared with the results coming out from the simulations are really precious and can provide useful information to improve the description of the physics phenomena in the simulation models.
My PhD research activity was held in this framework, as part of the research project Analysis of Reactor COre (ARCO, promoted by INFN) whose task was the development of modern, flexible and integrated tools for the analysis of nuclear reactors, relying on the experimental data collected at the research reactor TRIGA Mark II, installed at the Applied Nuclear Energy Laboratory (LENA) at the University of Pavia. In this way, once the effectiveness and the reliability of these tools for modeling an experimental reactor have been demonstrated, these could be applied to develop new generation systems.
In this thesis, I present the complete neutronic characterization of the TRIGA Mark II reactor, which was analyzed in different operating conditions through experimental measurements and the development of a Monte Carlo simulation tool (relied on the MCNP code) able to take into account the ever increasing complexity of the conditions to be simulated.
First of all, after giving an overview of some theoretical concepts which are fundamental for the nuclear reactor analysis, a model that reconstructs the first working period of the TRIGA Mark II reactor, in which the “fresh” fuel was not heavily contaminated with fission reaction products, is described.
In particular, all the geometries and the materials are described in the MCNP simulation model with good detail, in order to reconstruct the reactor criticality and all the effects on the neutron distributions.
The very good results obtained from the simulations of the reactor at low power condition -in which the fuel elements can be considered to be in thermal equilibrium with the water around them- are then used to implement a model for simulating the full power condition (250kW), in which the effects arising from the temperature increase in the fuel-moderator must be taken into account. The MCNP simulation model was exploited to evaluate the reactor power distribution and a dedicated experimental campaign was performed to measure the water temperature within the reactor core. In this way, through a thermal-hydraulic calculation tool, it has been possible to determine the temperature distribution within the fuel elements and to include the description of the thermal effects in the MCNP simulation model.
Thereafter, since the neutron flux is a crucial parameter affecting the reaction rates and thus the fuel burnup, its energy and space distributions are analyzed presenting the results of several neutron activation measurements.
Particularly, the neutron flux was firstly measured in the reactor's irradiation facilities through the neutron activation of many different isotopes. Hence, in order to analyze the energy flux spectra, I implemented an analysis tool, based on Bayesian statistics, which allows to combine the experimental data from the different activated isotopes and reconstruct a multi-group flux spectrum. Subsequently, the spatial neutron flux distribution within the core was measured by activating several aluminum-cobalt samples in different core positions, thus allowing the determination of the integral and fast flux distributions from the analysis of cobalt and aluminum, respectively.
Finally, I present the results of the fuel burnup calculations, that were performed for simulating the current core configuration after a 48 years-long operation. The good accuracy that was reached in the simulation of the neutron fluxes, as confirmed by the experimental measurements, has allowed to evaluate the burnup of each fuel element from the knowledge of the operating hours and the different positions occupied in the core over the years. In this way, it has been possible to exploit the MCNP simulation model to determine a new optimized core configuration which could ensure, at the same time, a higher reactivity and the use of less fuel elements.
This configuration was realized in September 2013 and the experimental results confirm the high quality of the work done.
The results of this Ph.D. thesis highlight that it is possible to implement analysis tools -ranging from Monte Carlo simulations to the fuel burnup time evolution software, from neutron activation measurements to the Bayesian statistical analysis of flux spectra, and from temperature measurements to thermal-hydraulic models-, which can be appropriately exploited to describe and comprehend the complex mechanisms ruling the operation of a nuclear reactor.
Particularly, it was demonstrated the effectiveness and the reliability of these tools in the case of an experimental reactor, where it was possible to collect many precious data to perform benchmark analyses.
Therefore, for as these tools have been developed and implemented, they can be used to analyze other reactors and, possibly, to project and develop new generation systems, which will allow to decrease the production of high-level nuclear waste and to exploit the nuclear fuel with improved efficiency.
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Guerriero, Andrew. "Variable pressure NMR analyses to assess compressive motion in PETNR and catalytically germane PETNR:Ligand complexes." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/variable-pressure-nmr-analyses-to-assess-compressive-motion-in-petnr-and-catalytically-germane-petnrligand-complexes(f9d8a882-b05b-47ac-86c4-3987c78e5494).html.
Full textAbstract:
The involvement of dynamical fluctuations in driving enzymatic processes is widely accepted. With respect to NQM tunnelling enzymes, the role of promoting motions in facilitating hydrogenic transfers is well studied. Few studies have however, specifically attributed, dedicated dynamical fluctuations characterised by their timescales and magnitudes, as a function of a reaction coordinate, to specific groups in a protein system. An effectively full suite of backbone resonance assignments were obtained for PETNR and on relevant ligand complexes. This provided an essential platform on which residue specific, backbone amide fluctuations were assessed. This thesis documents the application of pressure up to 1500 bar, in tandem with high resolution TROSY based NMR analysis, as a means of studying residue specific, conformer exchange perturbations. Residue specific amide compression profiles of the PETNR:FMN free enzyme system, and complexes with progesterone and tetrahydropyridine dinucleotides have been obtained. The binding of progesterone appears to induce conformational tightening of residues within the active site vicinity. The complexation of PETNR:FMN with tetrahydropyridine dinucleotides, appears to stimulate conformational shifts towards intermediate, and in some cases, slow exchange regimes in multiple residues about the active site vicinity. This is evidenced by extensive intensity attenuation of 1H-15N TROSY resonances, on the binding of tetrahydropyridine dinucleotides at 1 bar pressure, and on going from 1 bar to 1500 bar pressure. Multiple regions of sequence, spatially clustering about the active site vicinity within a 10 Å sphere of the FMN binding pocket, display appreciable sensitivity to ligand binding. Differential responses of residues to the application of high pressure between complexes was noted within segments of these regions. A region of sequence, named the β-hairpin flap displays significant differential compression profiles between the PETNR:FMN free enzyme system, and associated progesterone and tetrahydropyridine dinucleotide complexes. A role in mediating ligand engagement is proposed for R130 and R142 in the β-hairpin flap. A central hydrogen bonding network, perhaps constituting a putative proton wire in the active site of the PETNR:FMN:Progesterone complex, has been identified that could enable the shuttling of protons following catalytic protonation of oxidative substrate. The resonance response behaviour of G185 acts as a sensitive reporter on the formation of these interactions, revealed by an interrogation of the differences in chemical shift changes on progesterone binding, and in response to high pressure. The recruitment of high resolution crystallographic data sets readily supported a structural and dynamical interpretation of the observed chemical shift responses to ligand binding at 1 bar pressure, and on the application high pressure. A definitive atomistic identification of fast motion contribution to activation barrier compression was not obtained. Nevertheless, detailed, residue specific amide compression profiles, and shifts in backbone amide conformational exchange regimes in response to ground state ligand binding, and at high pressure, have been catalogued in the PETNR:FMN free enzyme system. These dynamical profiles in the free enzyme are contrasted against comparative, residue specific observations in analogue complexes of the oxidative and reductive half reactions of PETNR.
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Lycoudi, Maria. "Neutron activation analysis for the determination of gold and the platinum group elements in large samples." Thesis, 1994. https://hdl.handle.net/10539/31189.
Full textAbstract:
A dissertation submitted to the Faculty of Science
University of the Witwatersrand, Johannesburg,
for the Degree of Master of Science.The method of activation analysis is extended to the analysis of very large samples (up to 1kg) of ores and minerals. The use of such large samples has two advantages: first, the sensitivity of the method is greatly increased, and secondly, inhomogeneity of distribution and hence sampling problems are greatly reduced. Samples are used without any kind of treatment and the method is non - destructive. There are also disadvantages associated with the use of large samples. Absorption effects (both of neutron and y - rays) become important and as a result the calibration curves are influenced by the bulk density and composition of the samples. In certain cases, the calibration curves may also be non - linear. These effects have been studied in detail for the determination of gold, through the reaction 198Au(n,y)l98Au. After irradiating various samples of known concentrations of gold, calibration curves for gold in gold ore and carbon samples have been established. The effect of y -ray and neutron absorption has been studied in carbon samples using either thermal or epithermal neutrons and the optimum sample thickness has been established. In addition, the curve for the optimum decay time has been obtained for gold in ore samples. Based on the experimental results, a theoretical model has been applied to study the variation of the statistical error with the various factors involv~d, i.e. irradiation, decay, counting times, source strength and sample size. It has been also used to analyse theoretically the results for the optimum thickness and the variation of the background under the 411. 8 keV peak of Au-198. Further work has been undertaken to investigate whether the method can be used to determine elements from the platinum group which are much less active than the gold. Gamma ray peaks from Ir - 192, Au - 199, Pt - 199 Rh - 104m and Os-193 could be identified and possibly from Pd-109. Further work is necessary to study each element separately. In the case of gold, very satisfactory results were obtained. It is too early to state that it provides a replacement for the fire - essay method for gold, but the potential definitely exists.
Andrew Chakane 2021
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Damarupurshad, Ashok Kumar. "Geochemistry of single diamond crystals by instrumental neutron activation analysis." Thesis, 2015. http://hdl.handle.net/10539/17024.
Full text
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Sedumedi, Lerato. "Radiometry of milk and mineral water from the Western Cape / Lerato Sedumedi." Thesis, 2003. http://hdl.handle.net/10394/11421.
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Pitout, Richard. "Pharos : pluri-director, high-resolution, analyser of radiometric properties of soil cores." Thesis, 2001. http://hdl.handle.net/10413/5467.
Full textAbstract:
The core-logger has been designed for the high-resolution radiometric analysis of soil
cores using multiple detectors. This device allows for the automation of the
measuring process and eliminates the need to dissect the cores. The design is aimed
at measuring soil-cores with a 10cm radius and a length of 1m and allows for up to 4
detectors to be mounted on the measuring platform. Currently a combination of
Bismuth-German.te (BGO) and C.esiwn-Iodide (CsI) detectors are used.
The core logger required a good spatial resolution of - 1 cm. This has been difficult to
obtain and has required extensive investigation. The shielding configurations were
varied and the effect of background radiation was looked at in detail to determine an
optimal construction. A secondary objective has been the complete measurement of a
single core in 24 hours. This has also been difficult to achieve because the low
activity of natural radiation in the core samples needs longer measuring times. The
BGO detectors were used as a more efficient detector (than, e.g. CsI) which helped to
reduce the required measuring time.
Measured spectra have been analysed to determine the activity concentrations of the
specific radionuclides of interest: 232Th, 238U, 40K and 137Cs. These activity profiles of
the measured cores provide information that can then be used to radiometrically
fingerprint the sample to determine soil characteristics such as grain size and mineral
content. However, because the actual resolution of the system ( ~3cm) is greater than
the typical core slice (~ 2cm), the radiometric information in a specific core-slice
contains contributions from its adjacent slices. This folding or convolution of the
measured spectra can be undone using a deconvolution method. which was examined
and commented on.Thesis (M.Sc.)-University of Natal, Durban, 2001.
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Copple, Blake Robert. "Development of a fully automated rapid irradiated sample transport system for neutron activation analysis." Thesis, 2014. http://hdl.handle.net/2152/28282.
Full textAbstract:
The need for trace, minor and main element analysis becomes more prevalent each year with an every expanding variety of applications. Neutron Activation Analysis (NAA) is an attractive non-destructive analysis tool that can be utilized on small samples regardless of what physical state the material is in. The analysis process however, typically requires researchers to physically handle a radioactive sample in order to transport the sample to detection systems for data gathering. The purpose of this project was to design a Fully Automated Rapid Irradiated Sample Transit (FARIST) system that could deliver samples into a reactor core and then transfer them to a detector for analysis with zero human interaction. The system would be designed to hold up to 30 samples prior to analysis with the irradiation, decay, and counting times programmed in initially so that once analysis was initiated, no user interaction was required for the next 29 samples. The last requirement of the system was that it supports cyclic NAA. This work discusses the science and history behind NAA as well as the design, construction, installation, and testing of the new FARIST system.text