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

Explorando novas metodologias em espectrometria de massas com ionização ambiente e fluorescência de raios X por dispersão em energia / Exploring new methodologies in ambient ionization mass spectrometry and energy dispersive X-ray fluorescence

Schwab, Nicolas Vilczaki, 1986- 25 February 2015 (has links)
Orientadores: Marcos Nogueira Eberlin, Maria Izabel Maretti Silveira Bueno / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T15:37:04Z (GMT). No. of bitstreams: 1 Schwab_NicolasVilczaki_D.pdf: 3814064 bytes, checksum: 830504748a20c22da41317192a1c7d9b (MD5) Previous issue date: 2015 / Resumo: O atual avanço na tecnologia em instrumentação analítica permite análises químicas cada vez mais rápidas e eficientes. Assim, o desenvolvimento de métodos que consistem em minimizar ou eliminar o preparo de amostra apresentam um grande diferencial em relação aos procedimentos tradicionais. Duas técnicas se destacam nesse sentido: a espectrometria de massas com ionização ambiente e a fluorescência de raios X por dispersão em energia. Com características distintas, essas técnicas abrangem um enorme campo de aplicações na ciência. Seguindo este conceito, esta tese de doutorado está dividida em três partes, que ilustram as diferentes aplicações utilizando uma das técnicas mencionadas. Primeiramente, foi relatada a produção e caracterização de superfícies funcionalizadas à base de silício poroso, como substrato para espectrometria de massas com ionização ambiente por dessorção via electrospray (DESI-MS). Os resultados encontrados mostraram que estas superfícies são excelentes alternativas como substrato para análises em DESI-MS, levando a baixos limites de detecção, eliminação de problemas referentes à contaminação cruzada e melhora na estabilidade do sinal analítico. O capítulo seguinte descreve o desenvolvimento de uma fonte portátil para ionização ambiente de moléculas por espectrometria de massas, que elimina a necessidade do uso de cilindros de gás e bombas injetoras. Sua eficiência foi comprovada por meio de análises de diversos compostos, gerando expectativas futuras para aplicações em campo, para resolução de casos analíticos conjuntamente com uso de equipamentos miniaturizados de espectrômetros de massas. Na parte final, foi demonstrado o uso da técnica de fluorescência de raios X na filatelia. Trata-se de uma técnica não destrutiva, onde, obteve-se o perfil elementar característico de diversas amostras de selos postais antigos como, por exemplo, os elementos relacionados à composição das tintas utilizadas na impressão. Como consequência, essa metodologia pode ser utilizada na discriminação em casos de falsificação de peças raras / Abstract: The advancement in analytical instrumentation allows today faster and more efficient chemical analysis. The development of new methods with regards to minimize or eliminate sample preparation steps has a great advantage over traditional procedures. Two techniques stand out in this concept: the ambient ionization mass spectrometry and energy dispersive X-ray fluorescence. With different characteristics, both techniques cover a huge range of applications in analytical chemistry. Following this idea, this thesis is divided into three parts that demonstrates some applications using the techniques mentioned earlier. The first chapter describes the production and characterization of functionalized porous silicon surfaces as substrates for desorption ionization electrospray mass spectrometry (DESI-MS). The results showed that specific surfaces provides an excellent alternative for spot analysis in DESI-MS, increasing detectability, eliminating cross-contamination problems and improving the analytical signal stability. The next chapter reports the development of a portable ambient ionization source for mass spectrometry, which eliminates the use of gas cylinders and injection pumps. Its efficiency was confirmed by analysis of several compounds leading to prospects for field applications; using for example with miniaturized mass spectrometers. Finally, the last chapter demonstrates the use of X-ray fluorescence in philately. The method developed is nondestructive and is a suitable technique to detect elements related with the composition of inks that are used to print stamps. For this reason, this is a powerful methodology to identify counterfeit samples of rare stamps mainly / Doutorado / Quimica Analitica / Doutor em Ciências
2

Estudo fitoquímico de Palicourea officinalis e distribuição espacial dos metabólitos secundários das folhas de espécies de Psychotria e Palicourea por DESI-MS direto e indireto / Phytochemical study of Palicourea officinalis and spatial distribution of secondary metabolites of leaves of Psychotria and Palicourea species by direct and indirect DESI-MS imaging

Moraes, Aline Pereira 07 April 2017 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-07-25T12:53:59Z No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-07-26T11:58:55Z (GMT) No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-07-26T11:58:55Z (GMT). No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-04-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Palicourea and Psychotria (Rubiaceae) are known for the presence of compounds with potential biological activity, such as the indole alkaloids, flavonoids and norisoprenoids. In order to increase the chemical knowledge of Palicourea species, the phytochemical study of the aerial parts of Palicourea officinalis was carried out for the first time, through the isolation by chromatography and structural elucidation of the compounds by NMR and mass spectrometry. The following secondary metabolites were identified: the novel alkaloid 18-epi-brachycerine; the norisoprenoids: guettardionoside, 3-oxo--ionol 9-O--D-apiofuranosyl-(1®6)--D-glucopyranoside, vomifoliol 9-O--D - apiofuranosyl-(1®6)--D-glucopyranoside and 7,8-dihydro-vomifolol 9-O--D-apiofuranosyl-(1®6)--D-glucopyranoside; the lignan syringaresinol--D-glucoside; the pyrazines 2,5-deoxyfructosazine, 2,6-deoxyfructosazine and fructosazine; the flavonoids quercetin 3-O-sophoroside and kampferol 3-O-sophoroside; 3-caffeoyl and 4-caffeoylquinic acids; feruloylquinic acids; salicylic acid; coumarin scopoletin; besides ursolic and oleanolic triterpenes acids and glycosylated sitesterol and stigmasterol steroids. In addition, for the first time, the indirect and direct DESI-MSI techniques were applied in the study of the spatial distribution of alkaloids in the leaves of Palicourea coriacea and Psychotria prunifolia. The indirect approach was applied successfully and showed distinct distribution patterns of the alkaloids detected. The image data were confirmed by LC-MS. / Palicourea e Psychotria (Rubiaceae) são gêneros conhecidos pela presença de compostos com potencial atividade biológica, tais como os alcaloides indólicos, flavonoides e norisoprenoides. Com o objetivo de ampliar o conhecimento químico de espécies de Palicourea, foi realizado pela primeira vez o estudo fitoquímico das partes aéreas de P. officinalis, através do isolamento por cromatografia e elucidação estrutural dos compostos por RMN e espectrometria de massas. Os seguintes metabólitos secundários foram isolados e identificados: o alcaloide inédito 18-epi-braquicerina; os norisoprenoides: guettardionosídeo e 3-oxo--ionol 9-O--D-apiofuranosil(1”®6’)- -D-glicopiranosídeo e a mistura vomifoliol 9-glicopiranosídeo, vomifoliol 9-O--D-glucopiranosil-(1®6)--D-apiofuranosídeo e 7,8-diidro-vomifoliol 9-O--D-glucopiranosil-(1®6)--D-apiofuranosídeo; a lignana siringaresinol-4’--D-glicosídeo; a mistura de pirazinas 2,5-desoxifructosazina, 2,6-desoxifructosazina e fructosazina; os flavonoides quercetina 3-O-soforosídeo e canferol 3-O-soforosídeo; os ácidos clorogênicos 3-cafeoil e 4-cafeoil-quínicos; uma mistura de ácidos feruloil-quínicos; ácido salicílico; a cumarina escopoletina; além das misturas dos triterpenos ácidos ursólico e oleanólico e dos esteroides sitosterol e estigmasterol glicosilados. Além disso, pela primeira vez, as técnicas de produção de imagem química por DESI-MS direto e indireto foram aplicadas no estudo da distribuição espacial dos alcaloides nas folhas de Palicourea coriacea e Psychotria prunifolia. O método indireto apresentou melhores resultados, com distintos padrões de distribuição dos alcaloides detectados. Os dados da imagem foram confirmados por LC-MS.
3

The Development and Applications of Soft Visible-Wavelength LDI, UV LDI, and DESI Sources for the Analyses of Biomolecules by Mass Spectrometry

West, Raymond Edward, III January 2016 (has links)
No description available.
4

Marine natural products as antimicrobial chemical defenses and sources of potential drugs

Lane, Amy L. 11 November 2008 (has links)
Marine organisms are widely recognized sources of an impressive array of structurally unusual compounds. Marine natural products have exhibited interesting biomedical activities, provided targets for synthetic organic chemists, and afforded opportunities for elucidation of enzymatic mechanisms involved in biosyntheses of these molecules. Secondary metabolite pathways probably evolved to mediate interactions between organisms in their natural habitats; however, the ecological functions of natural products remain poorly understood for the vast majority of cases. In the present series of investigations, I evaluate the hypothesis that macroalgal natural products play a role in defending these organisms against potentially pathogenic microbes in the marine environment. Further, I combine these ecology-driven investigations with evaluation of algal natural products as sources of novel human drugs. This combined approach resulted in discovery of 15 novel natural products from two tropical red algae, Callophycus serratus and an unidentified crustose red alga. These new molecules included seven novel carbon-carbon connectivity patterns, not previously reported in the synthetic or natural product literature, illustrating the abundance of secondary metabolite diversity among marine macroalgae. Further, many compounds exhibited both biomedical and ecological activities, suggesting the synergistic potential of combined biomedical/ecological investigations in providing drug leads as well as insights into the natural functions of secondary metabolites. Bromophycolides and callophycoic acids, natural products from C. serratus, inhibited growth of the marine fungal pathogen Lindra thalassiae. Spatially-resolved desorption ionization mass spectrometry (DESI-MS) revealed that antifungal natural products were found at specific sites on algal surfaces. The heterogeneous presentation of antimicrobial chemical defenses on host surfaces suggests the potential importance of spatial scale in understanding host-pathogen interactions, and illustrates the capacity of mass spectrometry imaging in understanding chemically-mediated biological processes. Finally, assessment of antimicrobial chemical defenses among extracts from 72 collections of tropical red algae revealed that nearly all algae were defended against at least one marine pathogen or saprophyte and further suggested the untapped potential of ecological investigations in the discovery of novel chemistry.
5

Využití DESI/DAPPI-MS a MALDI-MS pro studium biologických objektů / Utilization of DESI/DAPPI-MS and MALDI-MS for studying biological objects

Kaftan, Filip January 2013 (has links)
(EN) Presented PhD thesis was aimed at the utilization of desorption ionization mass spectrometric techniques to study different types of biological samples. An important part of this thesis was the construction of a universal platform for ambient ionization techniques (AIT) in mass spectrometry (MS) for the experiments performed in combination with desorption electrospray ionization (DESI) and desorption atmospheric pressure photoionization (DAPPI). Initially manual platform for AIT was during the development rebuild into a motorized platform operated by software via user interface of the mass spectrometer. Using the motorized platform it was possible to carry out a one- dimensional (1-D) and two dimensional (2-D) samples analysis with a defined step size of imaging. Platform designed for AIT in MS was tested in DESI-MS mode by model analyte Rhodamine B and by plant samples which were represented by Aconitum plicatum. The platform was also tested on biological samples of vernix caseosa using DAPPI-MS ion source. Model analyte rhodamine B was in DESI-MS technique used to study the basic desorption ionization processes occurring in the DESI during the sample analysis. In order to highlight the surface structures the colloidal solution of ferrite nanoparticles was added into the sprayed liquid. For...

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