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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

HCA e PCA de espectros FT-IR e UV-VIS de ácidos húmicos e DRX de solos de TPI

Loureiro, João Vitor Silva de 15 May 2015 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-10-26T15:25:30Z No. of bitstreams: 1 Dissertação - João Vitor Silva de Loureiro.pdf: 2409815 bytes, checksum: 3450dbc2ad4f05bc1bd2ccbd06e220a6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-26T18:05:45Z (GMT) No. of bitstreams: 1 Dissertação - João Vitor Silva de Loureiro.pdf: 2409815 bytes, checksum: 3450dbc2ad4f05bc1bd2ccbd06e220a6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-26T18:07:52Z (GMT) No. of bitstreams: 1 Dissertação - João Vitor Silva de Loureiro.pdf: 2409815 bytes, checksum: 3450dbc2ad4f05bc1bd2ccbd06e220a6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-26T18:21:27Z (GMT) No. of bitstreams: 1 Dissertação - João Vitor Silva de Loureiro.pdf: 2409815 bytes, checksum: 3450dbc2ad4f05bc1bd2ccbd06e220a6 (MD5) / Made available in DSpace on 2015-10-26T18:21:27Z (GMT). No. of bitstreams: 1 Dissertação - João Vitor Silva de Loureiro.pdf: 2409815 bytes, checksum: 3450dbc2ad4f05bc1bd2ccbd06e220a6 (MD5) Previous issue date: 2015-05-15 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The formation of Terra Preta (TPI) intrigued many researchers, besides it has too many hypotheses, the most likely involves human activities, whose origin is related to the deposition of material remained of pre-Columbian populations. It resulted in soils rich in humic acid (HA) that are regarded as natural binders most widely distributed in nature, which greatly contributes to soil fertility. This study applied statistical methods of multivariate analyzes such as hierarchical cluster analysis (HCA), Principal Component Analysis (PCA), infrared spectra Fourier Transform (FT-IR) and ultraviolet-visible spectra (UV-Vis) AH ICC for eight sites in the Amazon region, and applied to spectra of X-ray diffraction (XRD) of soil same eight sites of the ICC. Statistical methods were applied using the R software that makes use of normalization of the data obtained from each spectrum to generate the results of PCA and HCA. Using r software tools, it was possible observe which functional groups and stretches contributed positively OH, C=O and C=C, to generate graphics of PCA and HCA extracted from the FT-IR spectra. As for the results of UV-Vis spectra it was not possible to observe that groups could contribute to generation of HCA and PCA. For the XRD spectra it was observed that the PC1 that kaolinite and illite were the most positive contribution to the graphics, the PC2 that in most of the contribution was quartz. Thus, the simple application of HCA and PCA in the spectra allowed to compare the eight sites and classifies them according to similarity of the spectra. / A formação da Terra Preta de Índio (TPI) intriga muitos pesquisadores, por mais que exista muitas hipóteses, a mais plausível envolve atividades antrópicas, cuja origem está relacionada à deposição de restos de materiais de populações précolombianas. O que resultou em solos ricos em ácidos húmicos (AH), que são consideradas ligantes naturais mais amplamente distribuídos na natureza, o que contribui bastante para a fertilidade do solo. Neste estudo foi aplicado os métodos estatísticos de análises multivariadas como Análise de Agrupamentos Hierárquicos (HCA) e Análise de Componentes Principais (PCA) de espectros de infravermelho com Transformada de Fourier (FT-IR) e espectros de ultravioleta-visível (UV-Vis) para AH de oito sítios de TPI da região amazônica, e aplicado para espectros de difração de raios x (DRX) de solos dos mesmos oito sítios de TPI. Os métodos estatísticos foram aplicados com software R, que faz uso de normalização dos dados obtidos de cada espectro para geração dos resultados de HCA e PCA. Com ajuda das ferramentas do software R foi possível observar grupos funcionas ou estiramentos contribuíram positivamente, O-H, C=O e C=C, para gerar os gráficos de HCA e PCA extraídos dos espectros FTIR. Já para os resultados obtidos dos espectros UV-Vis não foi possível observar que grupamentos poderiam contribuir para geração do HCA e PCA. Quanto aos espectros dos de DRX foi possível observar que que na PC1 a caulinita e a ilita foram as que mais contribuíram positivamente para os gráficos, quanto que na PC2 a maior parte da contribuição foi do quartzo. Dessa forma, a simples aplicação de HCA e PCA nos espectros permitiu comparar os oitos sítios e classifica-los segundo similaridades dos espectros.
32

Vulnérabilité des ouvrages en maçonnerie à des mouvements de terrain : méthodologie d'analyse par méthodes statistiques et par plans d'expériences numériques sur les données de la ville de Joeuf / Vulnerability of masonry structures to ground movement : methodology of analysis by statistical methods and numerical experimental designs applied on Joeuf city data

Abdallah, Mouhammed 06 May 2009 (has links)
Le contexte de l’étude est celui des mouvements de terrain susceptibles de se produire à la suite d’un affaissement minier caractéristique de Lorraine et de leurs conséquences sur les habitations en maçonnerie traditionnelle. Quand de tels affaissements se produisent, ces habitations subissent en effet des désordres qui résultent des efforts engendrés dans la structure par les mouvements du terrain. La réponse qui caractérise alors l’état global de la structure dépend des caractéristiques géométriques, physiques et mécaniques. Or, la nature discontinue des maçonneries et la complexité des interactions entre blocs dans ces maçonneries rend complexe et difficile la détermination de cette réponse. Il en est de même de l’interaction sol-structure. L’objectif de la recherche consiste donc à étudier, par modélisation numérique avec la méthode des éléments distincts et par la technique des plans d’expérience et des surfaces de réponse, le comportement d’ouvrages en maçonnerie soumis à un affaissement minier caractéristique et à dégager de cette étude des critères permettant d’estimer, à l’échelle d’une ville entière, la vulnérabilité de tous ses bâtiments en maçonnerie. Une première analyse simplifiée expose le principe de la démarche mise en œuvre à l’échelle de la ville de Joeuf, utilisée comme site pilote. Elle repose sur l’analyse de la longueur cumulée des joints ouverts, assimilés à la formation de fissures dans la structure. Ensuite, une analyse typologique permet de distinguer 4 groupes de maisons aux caractéristiques proches. Sur chacun de ces groupes, la démarche est ensuite appliquée de manière systématique. Elle prend en considération des caractéristiques géométriques des façades et aboutit à la formulation de fonctions de vulnérabilité qui font appel à la technique de régression orthogonale / The context of our study concerns ground movements that may occur in Lorraine as a result of mining subsidence events and their impact on traditional masonry houses. When such an event occurs, houses suffer disorders resulting from efforts in the structure caused by the movement of the ground. The response that characterizes the state of the structure depends on the geometrical, physical and mechanical characteristics. However, the discontinuous nature of the masonry and the interactions complexity between masonry blocks makes it difficult to determine that response. The same is true about the soil-structure interaction. The purpose of this research is to study, by numerical modelling with the distinct element method, experimental design planning and response surfaces, the behaviour of masonry structures subjected to a typical mining subsidence event and to define from this study some criteria making possible the estimation of the vulnerability of all the buildings of a city. A first simplified analysis describes the principle of the used methodology which is then applied to the study of all houses of the city of Joeuf, used as a pilot site. This methodology is based on an analysis of the total length of the opened joints, which are considered as similar to cracks in the structure. Then, a typology analysis helps first to distinguish 4 groups (types) of houses which have similar characteristics. On each of these groups, the methodology is applied consistently, based on the geometrical characteristics of the houses facades and then leads to the formulation of vulnerability functions that use the technique of orthogonal regression
33

Determinação de Fe, Cu, Mn, Ni, V e Ti em partículas totais em suspensão coletadas em uma área urbana da cidade de Aracaju, Sergipe

Almeida, Tarcísio Silva de 27 February 2012 (has links)
This study aimed to determine and assess the total concentration of trace elements associated with the total suspended particles (TSP) collected in an urban area of the Aracaju City, Sergipe, Brazil. Forty two samples were collected on glass fiber filters between period August/2009 and September/2010 using a high volume sampler (AGV). The concentration of Fe, Cu, Mn, Ni, V and Ti were determined employing atomic spectrometry techniques in two different work. The first used acid digestion extraction assisted by microwave and analysis by mass spectrometry and optical emission, both inductively coupled plasma (ICP OES and ICP MS). The concentrations of the elements found between <48 and 1620 ± 16 ng.m-3 for Fe; 0.70 ± 0.04 and 322 ± 4 ng.m-3 for Cu;<1,3 and 12.7 ± 6.8 ng.m-3 for Mn; 1.1 ± 0.1 and 16.0 ± 8.4 ng.m-3 for Ni; <15 and 49.3 ± 4.0 ng.m-3 for V and 4,6 ± 0,6 a 129,0 ± 12,5 ng.m-3 for Ti (n=41 samples). The exploratory data analysis results was applied. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) concluded that there are two emitters that contribute to the composition of the PTS that reach the sampling area. Soil resuspension is major contributor in the composition due to correlation between Fe, Mn, Ni and Ti, which are typical elements of the soil. The second emitter, is characteristic of the vehicular traffic. wherein the concentration of Cu, V, SO2 and smoke were likely indicative of action anthropogenic. The enrichment factor calculated for the concentration of the elements identified enrichment for the average concentration of copper found in the urban area, is another indication of anthropogenic inputs. The second study consisted of the Cu and Fe sequential determination in TSP using slurry sampling flame atomic absorption spectrometry and mode fast sequetial (FS-FAAS). The optimization univariate involved the following variables: the concentration of nitric acid used to prepare the slurry, sonication time and the sample mass. The optimized conditions, to about 50 mg of sample were: nitric acid solution 0.5 mol L-1, sonication time of 10 min and a final volume of 25 mL. The calibration curves were obtained using a slurry of a non-filter, the pattern multielement containing Cu and Fe in nitric acid 0.5 mol L-1. This strategy calibration offset the effect observed for the matrix Fe The limit of detection (LOD, 3σ, n = 10) was equal 4 μg.g-1 for Cu and 14 μg.g-1 for Fe , corresponding to 8 ng.m-3 for Cu and 20 ng.m-3 for Fe. The precison was expressed as relative standard deviation (RSD, n = 3) was smaller than 7% for the copper concentration and 8% for iron concentration in the slurries analysis (n=3). The concentrations of both elements determined by the proposed method were compared to concentrations obtained by ICP-MS after acid extraction assisted by microwave and showed no significant differences, applying the t test for a confidence level of 95%. The proposed procedure was simple, fast and reliable suitable for the sequential determination of Cu and Fe in PTS samples by FS-FAAS. / Este trabalho teve como objetivo determinar e avaliar a concentração total de elementos traço associados as partículas totais em suspensão (PTS) coletadas em uma área urbana da cidade de Aracaju, Sergipe, Brasil. Quarenta e duas amostras foram coletadas em filtros de fibra de vidro no período entre agosto/2009 e setembro/2010 utilizando um amostrador de grande volume (AGV). As concentrações de Fe, Cu, Mn, Ni, V e Ti foram determinadas empregando-se técnicas de espectrometria atômica em dois trabalhos distintos. O primeiro usou a digestão ácida assistida por micro-ondas e análise por espectrometria de massa e de emissão óptica, ambas com plasma indutivamente acoplado (ICP-MS e ICP OES). Foram encontradas as concentrações entre <48 a 1620 ± 16 ng g-1 para Fe; 0,70 ± 0,04 a 322 ± 4 ng.m-3 para Cu; 1,3 a 12,7 ± 6,8 ng.m-3 para Mn; 1,1 ± 0,1 a 16,0 ± 8,4 ng.m-3 para Ni, <15 a 49,3 ± 4,0 ng.m-3para V e 4,6 ± 0,6 a 129,0 ± 12,5 ng.m-3. Foi aplicada a análise exploratória de dados aos resultados. A partir da análise de componentes principais (PCA) e a análise de agrupamentos hierárquicos (HCA) concluiu-se que há dois emissores que contribuem na composição do PTS que atingem a área amostral. A ressuspensão do solo é o maior contribuidor na composição química, devido correlação encontrada entre Fe, Mn, Ni e Ti, que são elementos tipicos do solo. O segundo emissor é caracteristico do trafego veicular, onde a concentração de Cu, V, SO2 e Fumaça foram prováveis indicativos de ação antropogênica. O fator de enriquecimento calculado para a concentração dos elementos identificou o enriquecimento para a concentração de cobre encontrada na área urbana, sendo outro indicativo da ação antropogênica. O segundo trabalho consistiu da determinação sequencial de Cu e Fe no PTS usando amostragem em suspensão e espectrometria de absorção atômica com chama no modo seqüencial rápido ( fast sequential ) multi-elementar (FS-FAAS). A otimização univariada envolveu as seguintes variáveis: concentração da solução de ácido nítrico usada no preparo da suspensão, tempo de sonicação e massa da amostra. As condições otimizadas, para cerca de 50 mg de amostra, foram: solução de ácido nítrico 0,5 mol.L-1, tempo de sonicação de 10 min e um volume final de 25 mL. As curvas de calibrações foram obtidas, usando-se uma suspensão de um filtro não utilizado, contendo o padrão multielementar de Cu e Fe em meio de ácido nítrico 0,5 mol.L-1. Esta estratégia de calibração compensou o efeito de matriz verificado para o Fe. O limite de detecção (LD, 3σ, n=10) do método proposto foi igual a 4 μg.g-1 para Cu e igual a 14 μg.g-1 para Fe, que corresponde a 8 ng.m-3 para Cu e a 20 ng.m-3 para Fe. A precisão, expressa como o desvio padrão relativo (RSD, n=3), foi menor do que 7% para a concentração de Cu e a 8% para a concentração de Fe na análise das suspensões. As concentrações de ambos os elementos determinados pelo método proposto foram comparadas com as concentrações obtidas por ICP-MS após extração ácida assistida por micro-ondas e não apresentaram diferenças significativas, aplicando-se o teste t para um nível de confiança de 95%. O procedimento proposto é simples, rápido e confiável, adequado para a determinação sequencial de Cu e Fe em amostras de PTS por FS-FAAS.
34

Human Carbonic Anhydrase Ii; Preparation, Metal-Substitution, Activity, and Inhibition

Wilson, David L 14 August 2015 (has links)
This report details the activities and inhibition of metal-substituted human carbonic anhydrase II (M-HCA-II). The traditional activities (hydrolysis of CO2 and para-nitrophenol acetate) in addition to new activities (oxidation of 2-aminophenol, disproportionation of H2O2, and disproportionation of superoxide) were investigated. Values reported for the relative hydrolytic activities of M-HCA-IIs are reported here for the first time, ranging from 47.5 % (plus or minus 0.6) to 86 % (plus or minus 4) for the hydrolysis of CO2 and from 0.299 % (plus or minus 0.012) to 4.72 % (plus or minus 0.015) for the hydrolysis of para-nitrophenol acetate. With respect to new activities, only the oxidation of 2-aminophenol was observed. Turnover was observed for Fe-HCA-II (kcat/KM = 3.6 plus or minus 1.3 mM-1 s-1) and Cu-HCA-II (kcat/KM = 8 plus or minus 2 mM-1 s-1). Inhibition of Zn-, (di-substituted) Cu2-, and Cu/Zn-HCA-II hydrolysis of CO2 and para-nitrophenol acetate by sulfanilamide, coumarin, and ortho-coumaric acid were investigated. Sulfanilamide was shown to inhibit: Zn-HCA-II, Cu2-HCA-II, and Cu/Zn-HCA-II - (with CO2) KM = 8.9 plus or minus 1.1 microM, 11 plus or minus 2 microM, 8.8 plus or minus 1.4 microM and (with p-nitrophenyl acetate) KM = 8.4 plus or minus 1.0 microM, (none), 8.4 plus or minus 1.4 microM, respectively. No inhibition was observed for coumarin or ortho-coumaric acid or its derivatives for any CAs studied.
35

Reconnaissance de surfaces de protéines par les foldamères d'oligoamides aromatiques / Protein surface recognition using aromatic oligoamide foldamers

Vallade, Maëlle 29 September 2016 (has links)
Les protéines étant au coeur d’un grand nombre de processus biologiques, elles sont des cibles thérapeutiques largement convoitées. Les foldamères, notamment les oligoamides aromatiques, présentent une structure bien définie, prévisible, stable en solution et à l’état solide. Ajouté à cela, leur taille moyenne en fait de bons candidats pour la reconnaissance de surfaces de protéines, grâce à leurs chaînes latérales protéinogènes. Cette thèse présente les différentes étapes de leur conception, de la synthèse de la brique constitutive à l’obtention d’un foldamère fonctionnalisé grâce à la synthèse en phase supportée. La stratégie d’investigation des interactions entre un foldamère et une protéine est détaillée. L’originalité réside dans le fait que le foldamère est ancré directement à la protéine et le dichroïsme circulaire sert de méthode de screening. L’analyse structurale des hits permet de générer de nouveaux foldamères dans le but d’améliorer les interactions avec la protéine : c’est une stratégie itérative. Cette approche est appliquée premièrement à l’anhydrase carbonique humaine II, protéine modèle qui sert de preuve de principe pour cette approche ; puis à des protéines d’intérêt thérapeutique plus important : l’interleukine 4 et la cyclophiline A. Enfin, une étude concernant l’introduction de flexibilité au sein de foldamères de quinolines est présentée. / Since proteins are at the basis of many biological processes, they are widely studied as therapeutic targets. Aromatic oligoamide foldamers have a very well defined structure, predictable and stable both in solution and solid state. Because of their medium size, they appear as potent candidates for protein surface recognition thanks to their proteinogenic side chains. This manuscript presents the different steps of their design, from the scaffold’s synthesis to obtaining a functionalized foldamer, thanks to solid phase synthesis. The strategy to investigate protein/foldamer interactions will be detailed. Its originality lies in the fact that the foldamer is anchored to the protein. Circular dichroism has been used as a screening method to detect foldamer/protein interactions. Structural analysis of the hits will allow the design of new foldamers with the objective of enhancing foldamer/protein interactions: it is an iterative strategy. This approach has been applied firstly to human carbonic anhydrase II (HCA). This protein is used as a model system and proof of concept before moving to more therapeutically relevant proteins; interleukin 4 and cyclophilin A. Finally, a study on introducing flexibility in quinoline foldamers is presented.
36

Estratégias analíticas para determinação de espécies inorgânicas em medicamentos utilizados no tratamento de anemia ferropriva

Barbosa, Uenderson Araújo 28 September 2015 (has links)
Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-02-25T13:31:28Z No. of bitstreams: 1 Tese Uenderson Araujo Barbosa -final.pdf: 2006362 bytes, checksum: 7f8502d02bb06b7f75032fb7a79d79bc (MD5) / Approved for entry into archive by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-05-10T17:54:24Z (GMT) No. of bitstreams: 1 Tese Uenderson Araujo Barbosa -final.pdf: 2006362 bytes, checksum: 7f8502d02bb06b7f75032fb7a79d79bc (MD5) / Made available in DSpace on 2016-05-10T17:54:24Z (GMT). No. of bitstreams: 1 Tese Uenderson Araujo Barbosa -final.pdf: 2006362 bytes, checksum: 7f8502d02bb06b7f75032fb7a79d79bc (MD5) / CAPES e CNPq / Neste trabalho foram propostas estratégias analíticas visando à avaliação toxicológica de metais e metaloides em medicamentos utilizados no tratamento da anemia ferropriva, empregando técnicas cromatográficas e não cromatográficas. Na primeira parte desta tese determinou-se chumbo nos medicamentos aplicando espectrometria de absorção atômica com atomização eletrotérmica (ETAAS). O preparo da amostra foi realizado fazendo uso de digestão ácida em bloco digestor com sistema de refluxo “dedo frio” usando 3 mL de HNO3 (69% v/v) e 1 mL de H2O2 (30% v/v). Foram otimizadas as temperaturas de pirólise e atomização usando uma mistura de paládio e magnésio como modificador químico convencional, obtendo-se 1100ºC e 2000ºC para pirólise e atomização, respectivamente. Com uma massa característica de 21,3 pg e 0,25 e 0,82 µg L-1, para os limites de detecção (LD) e de quantificação (LQ), respectivamente. A precisão, expressa pelo desvio padrão relativo de 5.92% para uma amostra com concentração de chumbo igual a 2,98 µg g-1. A exatidão foi estimada por comparação entre os resultados obtidos por ETAAS e espectrometria de massas com plasma indutivamente acoplado (ICP-MS). As concentrações de chumbo nas amostras variaram entre 0,096 e 7,068 µg g-1. Na segunda parte deste trabalho, foi efetuada a determinação de mercúrio através de amostragem em suspensão e espectrometria de absorção atômica com alta resolução e fonte contínua com geração de vapor frio (HR-CS CVAAS). As condições ótimas de preparo das suspensões (1,5 mol L-1 de HCl, 1,25% (m/v) de tioureia e 15 minutos de sonicação) foram otimizadas por planejamento fatorial completo. Os limites de detecção e quantificação foram 0,63 ng g-1 e 2,11 ng g-1, respectivamente. O desvio padrão relativo para avaliação da precisão foi calculado usando duas amostras com concentrações 4,82 e 9,61 ng g-1 com resultados 10,89 e 6,84%, respectivamente. Foi estimada a possível perda de mercúrio durante o procedimento proposto e a exatidão, mediante testes de adição e recuperação, variando entre 85,0 e 106,0%. As concentrações de mercúrio ficaram entre 3,17 e 34,86 ng g-1. A terceira parte deste trabalho descreve a determinação de macro e microelementos e o estudo in vitro da bioacessibilidade de ferro em medicamentos usados no tratamento da anemia ferropriva. Foi escolhida a espectrometria de emissão ótica com plasma indutivamente acoplado (ICP OES) como técnica analítica de medida. Foi efetuada digestão ácida para tratamento das amostras e o método foi validado, demonstrando boa sensibilidade, com limites de quantificação (mg L-1) 0,52 para Ca, 0,14 para K, 0,03 para Mg, 0,07 para Mn, 0,40 para Na, 0,36 para P e 0,24 para Zn. A precisão do método foi reconhecida mediante experimentos repetitivos intradia e interdia com resultados abaixo de 20%. Durante estudo da exatidão, testes de adição e recuperação foram executados em diferentes concentrações com resultados entre 81,85 e 114,97%. A robustez do plasma foi calculada mediante uma razão entre as linhas iônica e atômica de magnésio, Mg(II)/Mg(I) e os resultados, mediante análise componentes principais (PCA) e análise por agrupamentos hierárquicos (HCA). O estudo de bioacessibilidade in vitro de Fe demonstrou que alguns medicamentos são melhores bioacessíveis, sendo portanto, mais recomendados para o tratamento da anemia, comprovando dados da literatura farmacológica. Na quarta parte deste trabalho descreve-se o estudo da determinação e especiação simultânea de arsênio e cromo por 11 cromatografia líquida de alta eficiência acoplada à ICP-MS (HPLC-ICP-MS). A determinação total de arsênio e cromo foi realizada usando uma digestão ácida em forno de micro-ondas, uma mistura de 4 mL HNO3 (69% v/v) e 1 mL de H2O2 (30% v/v) e análise por ICP-MS. Para o estudo de especiação foi elaborado um estudo com três possíveis procedimentos para extração das espécies, sendo selecionado um procedimento com água a 80ºC por 30 minutos em energia de micro-ondas. Usando uma fase móvel contendo 1,0 mM de hidróxido de tetrabutilamônio (TBAH), 0,7 mM de ácido etilenodiaminotetracético (EDTA) e 5% de metanol (v/v) em pH 7,2 foi possível separar as espécies presentes com tempo de retenção de 5 minutos com separação de As(III), As(V), Cr(III) e Cr(VI), com limites de detecção de 0,002, 0,003, 0,140 e 0,042 µg g-1, respectivamente. A exatidão do método foi avaliada conforme testes de adição e recuperação, entre 80,64 e 109,36%. O método foi aplicado em amostras do Brasil e Espanha, com concentrações entre 0,1-1,3 e 0,18-62,27 µg g-1 para As e Cr, respectivamente. / In this thesis work analytical strategies have been proposed for toxicological assessment of metals and metalloids in medicines used to treat iron deficiency anemia, using chromatographic and non-chromatographic techniques. In the first part of this thesis, lead was determined in drugs using electrothermal atomic absorption spectrometry (ETAAS). Sample preparation was performed using acid digestion in digester block with reflux system "cold finger" using 3 mL of HNO3 (69% v / v) and 1 mL of H2O2 (30% v / v). Pyrolysis and atomization temperatures were optimized using a mixture of palladium and magnesium as conventional chemical modifier, yielding 1100°C and 2000°C for pyrolysis and atomization, respectively. With a characteristic mass of 21.3 pg and 0.25 and 0.82 µg g-1, for limit of detection (LOD) and limit of quantification (LOQ), respectively. The accuracy, expressed as relative standard deviation was 5.92% for a sample with lead concentration of 2.98 µg g-1. The accuracy was evaluated by comparing the results obtained by ETAAS and inductively coupled plasma mass spectrometry (ICP-MS). Lead concentrations found in samples ranged between 0.096 and 7.068 µg g-1. In the second part of this work, the determination of mercury using slurry sampling and high resolution continuous source cold vapor atomic absorption spectroscopy (HR-CS CVAAS) was performed. The optimum conditions for preparation of slurries (1.5 mol L-1 HCl, 1.25% (w / v) thiourea and 15 minutes sonication) were optimized using a two level full factorial design. The limits of detection and quantification were 0.63 ng g-1 and 2.11 ng g-1, respectively. The relative standard deviation for accuracy evaluation was calculated using two samples with concentrations 4.82 and 9.61 ng g-1 from which was obtained as results 10.89 and 6.84%, respectively. The possible loss of mercury was evaluated for the proposed procedure and the accuracy was studied by addition/recovery test, with recoveries ranging from 85.0 to 106.0%. Mercury concentrations ranged between 3.17 and 34.86 ng g-1. The third part of this work describes the determination of macro and micro elements and the in vitro study of iron bioaccessibility in medicines used to treat iron deficiency anemia. It was used inductively coupled plasma optical emission spectrometry (ICP OES) measured as an analytical technique. Acid digestion treatment was conducted to the samples and the method was fully validated by demonstrating good sensitivity with quantification limits (mg L-1) 0.52 for Ca, 0.14 for K, 0.03 for Mg, 0.07 for Mn, 0.40 for Na, 0.36 for P and 0.24 for Zn. The precision of the method was evaluated by intraday and interday repetitive experiments with results below 20%. During accuracy evaluation, addition/recovery tests were performed at different concentrations with results between 81.85 and 114.97%. The robustness of plasma was evaluated by a ratio between magnesium atomic and ionic lines, Mg(II)/Mg(I). The results were evaluated by multivariate analysis tools, principal component analysis (PCA) and hierarchical cluster analysis (HCA). The study of in vitro bioaccessibility of Fe showed that some drugs are better bioaccessible, being therefore more recommended for anemia treatment, confirming data of pharmacological literature. The fourth part of this work describes the simultaneous determination of arsenic and chromium speciation using high-performance liquid chromatography coupled to ICP-MS (HPLC-ICP- MS). The total arsenic and chromium determination was carried out using an acid digestion in microwave oven, using a mixture of 4 mL HNO3 (69% v / v) 9 and 1 mL of H2O2 (30% v / v) and analyzed by ICP-MS. For speciation, a study was performed with three possible procedures for extraction of species, being employed a procedure with water at 80 °C for 30 minutes in microwave energy. Using a mobile phase containing 1.0 mM tetrabutylammonium hydroxide (TBAH), 0.7 mM ethylenediaminetetraacetic acid (EDTA) and 5% methanol (v / v) under pH 7.2 was possible the separation of the species present with retention time of 5 minutes with separation of As(III) As(V), Cr(III) and Cr(VI), with a LOD of 0.002, 0.003, 0.140 and 0.042 µg g-1, respectively. The accuracy was assessed using addition/recovery tests, ranging between 80.64 and 109.36%. The method was applied in samples from Brazil and Spain.
37

Multivariate spectroscopic methods for the analysis of solutions

Wiberg, Kent January 2004 (has links)
<p>In this thesis some multivariate spectroscopic methods for the analysis of solutions are proposed. Spectroscopy and multivariate data analysis form a powerful combination for obtaining both quantitative and qualitative information and it is shown how spectroscopic techniques in combination with chemometric data evaluation can be used to obtain rapid, simple and efficient analytical methods. These spectroscopic methods consisting of spectroscopic analysis, a high level of automation and chemometric data evaluation can lead to analytical methods with a high analytical capacity, and for these methods, the term high-capacity analysis (HCA) is suggested. It is further shown how chemometric evaluation of the multivariate data in chromatographic analyses decreases the need for baseline separation. </p><p>The thesis is based on six papers and the chemometric tools used are experimental design, principal component analysis (PCA), soft independent modelling of class analogy (SIMCA), partial least squares regression (PLS) and parallel factor analysis (PARAFAC). The analytical techniques utilised are scanning ultraviolet-visible (UV-Vis) spectroscopy, diode array detection (DAD) used in non-column chromatographic diode array UV spectroscopy, high-performance liquid chromatography with diode array detection (HPLC-DAD) and fluorescence spectroscopy. The methods proposed are exemplified in the analysis of pharmaceutical solutions and serum proteins.</p><p>In Paper I a method is proposed for the determination of the content and identity of the active compound in pharmaceutical solutions by means of UV-Vis spectroscopy, orthogonal signal correction and multivariate calibration with PLS and SIMCA classification. Paper II proposes a new method for the rapid determination of pharmaceutical solutions by the use of non-column chromatographic diode array UV spectroscopy, i.e. a conventional HPLC-DAD system without any chromatographic column connected. In Paper III an investigation is made of the ability of a control sample, of known content and identity to diagnose and correct errors in multivariate predictions something that together with use of multivariate residuals can make it possible to use the same calibration model over time. In Paper IV a method is proposed for simultaneous determination of serum proteins with fluorescence spectroscopy and multivariate calibration. Paper V proposes a method for the determination of chromatographic peak purity by means of PCA of HPLC-DAD data. In Paper VI PARAFAC is applied for the decomposition of DAD data of some partially separated peaks into the pure chromatographic, spectral and concentration profiles. </p>
38

Multivariate spectroscopic methods for the analysis of solutions

Wiberg, Kent January 2004 (has links)
In this thesis some multivariate spectroscopic methods for the analysis of solutions are proposed. Spectroscopy and multivariate data analysis form a powerful combination for obtaining both quantitative and qualitative information and it is shown how spectroscopic techniques in combination with chemometric data evaluation can be used to obtain rapid, simple and efficient analytical methods. These spectroscopic methods consisting of spectroscopic analysis, a high level of automation and chemometric data evaluation can lead to analytical methods with a high analytical capacity, and for these methods, the term high-capacity analysis (HCA) is suggested. It is further shown how chemometric evaluation of the multivariate data in chromatographic analyses decreases the need for baseline separation. The thesis is based on six papers and the chemometric tools used are experimental design, principal component analysis (PCA), soft independent modelling of class analogy (SIMCA), partial least squares regression (PLS) and parallel factor analysis (PARAFAC). The analytical techniques utilised are scanning ultraviolet-visible (UV-Vis) spectroscopy, diode array detection (DAD) used in non-column chromatographic diode array UV spectroscopy, high-performance liquid chromatography with diode array detection (HPLC-DAD) and fluorescence spectroscopy. The methods proposed are exemplified in the analysis of pharmaceutical solutions and serum proteins. In Paper I a method is proposed for the determination of the content and identity of the active compound in pharmaceutical solutions by means of UV-Vis spectroscopy, orthogonal signal correction and multivariate calibration with PLS and SIMCA classification. Paper II proposes a new method for the rapid determination of pharmaceutical solutions by the use of non-column chromatographic diode array UV spectroscopy, i.e. a conventional HPLC-DAD system without any chromatographic column connected. In Paper III an investigation is made of the ability of a control sample, of known content and identity to diagnose and correct errors in multivariate predictions something that together with use of multivariate residuals can make it possible to use the same calibration model over time. In Paper IV a method is proposed for simultaneous determination of serum proteins with fluorescence spectroscopy and multivariate calibration. Paper V proposes a method for the determination of chromatographic peak purity by means of PCA of HPLC-DAD data. In Paper VI PARAFAC is applied for the decomposition of DAD data of some partially separated peaks into the pure chromatographic, spectral and concentration profiles.
39

Combined Computational-Experimental Design of High-Temperature, High-Intensity Permanent Magnetic Alloys with Minimal Addition of Rare-Earth Elements

Jha, Rajesh 20 May 2016 (has links)
AlNiCo magnets are known for high-temperature stability and superior corrosion resistance and have been widely used for various applications. Reported magnetic energy density ((BH) max) for these magnets is around 10 MGOe. Theoretical calculations show that ((BH) max) of 20 MGOe is achievable which will be helpful in covering the gap between AlNiCo and Rare-Earth Elements (REE) based magnets. An extended family of AlNiCo alloys was studied in this dissertation that consists of eight elements, and hence it is important to determine composition-property relationship between each of the alloying elements and their influence on the bulk properties. In the present research, we proposed a novel approach to efficiently use a set of computational tools based on several concepts of artificial intelligence to address a complex problem of design and optimization of high temperature REE-free magnetic alloys. A multi-dimensional random number generation algorithm was used to generate the initial set of chemical concentrations. These alloys were then examined for phase equilibria and associated magnetic properties as a screening tool to form the initial set of alloy. These alloys were manufactured and tested for desired properties. These properties were fitted with a set of multi-dimensional response surfaces and the most accurate meta-models were chosen for prediction. These properties were simultaneously extremized by utilizing a set of multi-objective optimization algorithm. This provided a set of concentrations of each of the alloying elements for optimized properties. A few of the best predicted Pareto-optimal alloy compositions were then manufactured and tested to evaluate the predicted properties. These alloys were then added to the existing data set and used to improve the accuracy of meta-models. The multi-objective optimizer then used the new meta-models to find a new set of improved Pareto-optimized chemical concentrations. This design cycle was repeated twelve times in this work. Several of these Pareto-optimized alloys outperformed most of the candidate alloys on most of the objectives. Unsupervised learning methods such as Principal Component Analysis (PCA) and Heirarchical Cluster Analysis (HCA) were used to discover various patterns within the dataset. This proves the efficacy of the combined meta-modeling and experimental approach in design optimization of magnetic alloys.
40

Natural and Anthropogenic Sources Controlling Regional Groundwater Geochemistry on the Niagara Peninsula

Smal, Caitlin January 2017 (has links)
Groundwater chemistry on the Niagara Peninsula has been identified as highly mineralized in comparison to groundwaters collected from the same bedrock formations elsewhere in southern Ontario. Three geochemical zones were discerned using hierarchical cluster analysis and other geochemical and isotopic methods. The Escarpment Zone, located along the Niagara and Onondaga Escarpments, is characterized by unconfined aquifer conditions, parameters reflective of surficial contaminants, including road salt, and elevated HCO3, DOC, NO3-, coliform bacteria and tritium. In contrast, in the Salina Zone thick, low-permeability sediments and gypsiferous bedrock results in highly mineralized groundwaters with Ca-SO4 geochemical facies and elevated S2-, Ca2+, Mg2+, K+, Na+, SO42-, Cl-, Br-, Sr2+, NH4+ and CH4. The Guelph Zone contains the lowest electrical conductivity of the three zones and elevated F-. Outliers exist with groundwater geochemistry that differs from the local geochemical zone and the host aquifer. These sites have elevated SO42- (>1000 to 5200 mg/L) with depleted δ34SSO4 (-2.2 to 14.3‰ VCDT) signatures that differs starkly from Devonian and Silurian evaporites (~20 to 32 ‰) in the host formations. This exogenic SO4 was identified in a cross-formational northeast – southwest linear trend crossing three major groundwater flow systems. The lack of down-stream impact in these systems and tritium groundwater ages that are typically only decades old indicate a young, non-geological origin and implicate anthropogenic activities. Additionally, nine samples were identified with elevated methane concentrations and δ13CCH4 signatures within the thermogenic range. As thermogenic methane is not produced within shallow aquifers and would be short-lived in the presence of the ubiquitous sulfate, these samples imply recent upward migration of methane from depth through vertical conduits. Taken together, the evidence supports large-scale upward movement of fluids in the centre of the Niagara geochemical anomaly and more sporadic upward transport of gases over a wider area of the peninsula. The most likely vector is through corroded and leaking casings or boreholes of abandoned (century) gas wells that are common across the peninsula. / Thesis / Master of Science (MSc)

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