• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 15
  • 13
  • 13
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 57
  • 13
  • 12
  • 12
  • 8
  • 7
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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

Superbacteria carry new gene that makes them resist all antibacterials / Superbacterias portan nuevo gen que les hace resistir a todos los antibacterianos

Marchese Morales, Adolfo 25 September 2017 (has links)
Un grupo de científicos de China ha encontrado un nuevo gen en las bacterias gram negativas, el MCR-1. Este gen ha sido responsable de otorgarle resistencia a estas bacterias patógenas ante la colistina, el antibacteriano que los médicos emplean como última arma para combatir ciertas infecciones multi-resistentes. Con este gen, las superbacterias serán potencialmente epidémicas y las enfermedades que se creían controladas, como la neumonía, la tuberculosis y las infecciones del tracto urinario, podrían ser nuevamente letales. / A group of Chinese scientists have found a new gene in gram negative bacteria, the MCR-1. This gene has given pathogenic bacteria resistance to colistin, which is the antibacterial that medical doctors use as last line of defense against multi-drug resistant infections. Superbacteria with MCR-1 will be potentially epidemic, and diseases that were believed to be controlled such as pneumonia, tuberculosis and urinary tract infections could be lethal again.
2

Estudo da influencia da radiação e pH no comportamento cinetico de antocianinas de plantas do genero hibiscus por metodos quimiometricos / Study on the influence of radiation and pH at the knetic behavior of anthocynins from plants of hibiscus gender by chemometrics methods

Março, Paulo Henrique 13 August 2018 (has links)
Orientador: Ronei Jesus Poppi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T13:10:34Z (GMT). No. of bitstreams: 1 Marco_PauloHenrique_D.pdf: 2630074 bytes, checksum: 4918a95e8c129f263c743c2c5b2a98ee (MD5) Previous issue date: 2009 / Resumo: A influência da radiação UV e pH no equilíbrio de espécies de antocianinas de plantas do gênero Hibiscus foi estudada por métodos quimiométricos. Antocianinas provenientes de extratos de 3 diferentes flores da família Malvaceae (Hibiscus Sabdariffa, Hibiscus Acetosella e Malvaviscus Penduliflorus) foram utilizadas no estudo. Análises espectrofotométricas nas regiões UV-Vis foram realizadas, comparando-se os espectros e a cinética resultante de análises realizadas com e sem exposição à radiação UV em soluções tampão com valores de pH variando de 1,5 até 12,7 e Análise por Injeção em Fluxo (FIA) para o cálculo das constantes de equilíbrio dos compostos encontrados. Para isso, foram utilizados métodos quimiométricos de Análise de Componentes Principais (PCA), PCA multi-modo (MPCA), Pure, Decomposição de Valores Singulares (SVD) e Resolução Multivariada de Curvas com Mínimos Quadrados Alternados (MCR-ALS). Com o objetivo de encontrar com maior confiabilidade o número de espécies presentes assim como caracterizá-las, o método MCR-ALS foi aplicado utilizando-se matrizes individuais e também com matrizes aumentadas. A partir dos resultados obtidos pela aplicação dos métodos quimiométricos foi sugerido um sistema de equilíbrio entre as diferentes formas químicas encontradas nos diferentes valores de pH, e a partir dos resultados obtidos por FIA, foram calculadas as constantes de equilíbrio para algumas das espécies encontradas / Abstract: The influence of UV radiation and pH at the anthocyanin species equilibra, extracted from plants of Hibiscus gender was studied with chemometric methods. Anthocyanins from different extracts of 3 different flowers of Malvaceae family (Hibiscus Sabdariffa, Hibiscus Acetosella and Malvaviscus Penduliflorus) were used at this investigation. Spectrophotometric analysis at UV-Visible range were performed, comparing spectra and kinetic behavior from analysis with and without UV radiation exposure by using buffer solutions with pH varying from 1.5 to 12.7 and Flow Injection Analysis (FIA) to calculate the equilibra constants to the compounds found in the samples. Chemometric methods as Principal Components Analysis (PCA), Multy-Way PCA, Pure, Singular Value Decomposition (SVD), Multivariate Curve Resolution with Alterning Least Squares (MCR-ALS) were applied. Aiming to find out the number of species, as well as, to characterize them, the MCR-ALS method was applied by using individual and augmented matrix strategy. From the results of the chemometric methods application it was proposed an equilibra system to the species found at different pH values and from FIA results, the equilibra constants were calculated to some of the species / Doutorado / Quimica Analitica / Doutor em Ciências
3

Aplicação de métodos de resolução de curvas multivariada a dados experimentais gerados por diferentes técnicas analíticas = uma visão exploratória da biossíntese da violaceína / Application of multivariate curve resolution of experimental data generated by several analytical techniques : an exploratory overview of violacein biosynthesis

Muniz Filho, Raimundo Clecio Dantas 07 November 2011 (has links)
Orientador: Márcia Miguel Castro Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-19T01:35:46Z (GMT). No. of bitstreams: 1 MunizFilho_RaimundoClecioDantas_D.pdf: 4450185 bytes, checksum: 93734fb6cdec46f7ac2161a230dd978c (MD5) Previous issue date: 2011 / Resumo: A aplicação de métodos de resolução de curvas multivariada (MCR-ALS e PARAFAC) a dados de espectroscopia de fluorescência multicomprimento de onda, absorção molecular e cromatografia líquida de ultra eficiência com detecção por espectrometria de massas foi avaliada como um nova e complementar metodologia para se obter informação inicial sobre a biossíntese de produtos naturais. Para demonstrar o poder dessa proposta, a biossíntese da violaceína pela Chromobacterium violaceum foi usada como exemplo. A violaceína é um metabólito secundário que exibe amplo espectro de atividade biológica e o entendimento de sua rota biossintética pode ser de grande interesse para o planejamento de fármacos. Para tanto, uma cultura da C. violaceum foi cultivada em biorreator, onde, a cada duas horas, alíquotas do meio de cultura eram coletadas para subsequentes análises. Na primeira parte deste trabalho, as matrizes de emissão-excitação das amostras revelaram o comportamento dinâmico de fluoróforos envolvidos na biossíntese. O método de análise de fatores paralelos (PARAFAC) foi aplicado para resolver os perfis de fluorescência, onde seis espectros puros de emissão e excitação foram obtidos e suas relações com a biossíntese da violaceína estabelecidas. Na segunda parte, o método de resolução de curvas multivariada por quadrados mínimos alternados (MCR-ALS) foi utilizado para extrair informações simultâneas dos dados gerados por UV-VIS, fluorescência e UPLC-MS das amostras coletadas durante a biossíntese. Cinco compostos foram resolvidos e informações espectrais e temporais dessas espécies foram obtidas. Compostos com massas moleculares de 453, 465 e 479 u, até então não reportados na literatura como intermediários dessa biossíntese, foram identificados. Por fim, a metodologia baseada na aplicação de métodos de resolução de curvas MCR-ALS e PARAFAC provou ser uma poderosa ferramenta para investigar a biossíntese de produtos naturais / Abstract:The application of Multivariate Curve Resolution methods (MCR-ALS and PARAFAC) into multi-wavelength fluorescence spectroscopy, molecular absorption and ultra-performance liquid chromatography coupled to mass spectrometry data was evaluated as a new and complementary approach for the initial analysis of the biosynthesis of fluorescent natural products. To demonstrate the usefulness of this methodology, violacein biosynthesis by Chromobacterium violaceum was used as an example. Violacein is a secondary metabolite that exhibits a broad spectrum of biological activities and the understanding of its biosynthetic pathway can be of great interest for drug design. Therefore, a culture of C. violaceum was grown in a bioreactor from which aliquots were collected every two hours for subsequent analysis. In the first part of this work, the excitation¿emission matrices of the samples have revealed the dynamic behavior of the fluorophores involved in this biosynthesis. The parallel factor analysis (PARAFAC) method was applied to resolve the fluorescence profiles where six pure emission and excitation spectra were obtained and their relationship with violacein biosynthesis established. In the second part, the multivariate curve resolution procedure based on alternating least squares optimization (MCR-ALS) was used for extracting information from fused data (UV-VIS absorption, fluorescence and ultra-performance liquid chromatography with mass spectrometry) gathered during the violacein biosynthesis. Five chemical components were resolved from which spectral and temporal information were obtained. Compounds with molecular masses 453, 465 and 479 u, until now unreported as intermediate of this biosynthesis, were identified. Finally, the methodology based on the application of curve resolution methods PARAFAC and MCR-ALS has proven to be a unique and powerful tool to achieve a deeper insight of the biosynthesis of natural products / Doutorado / Físico-Química / Doutor em Ciências
4

Developing Peptide Probes for Membrane Lipids via Phage Display:

Kelly, Michael A. January 2020 (has links)
Thesis advisor: Jianmin Gao / Lipid reporters are key signaling molecules in a number of biological processes ranging from apoptosis in mammalian cells to novel resistance mechanisms in pathogenic bacteria. Developing probes to target these lipids is a worthy endeavor, especially when better reporters could mean lives saved. This is particularly true considering new antibiotic resistant pathogens emerge every year with evolving lipid compositions. To combat these pathogens and prevent a potential global pandemic, it is imperative to continue the development of novel and innovative probes/drugs to meet this daunting challenge. To fulfill this demand, we must continue to establish new strategies, enhance current technologies and advance scientific understanding. Only by pushing the boundaries of what is currently possible will we remain one step ahead of these diseases. Diseases like mcr-1 positive bacteria, first documented in 2016, remain largely uncontested. Herein, we seek to expand the available probes specific to key lipid reporters for phosphatidylserine, lysyl-phosphatidylglycerol, and phosphoethanolamine lipid A. Cyclic phage libraries were first utilized to target phosphatidylserine, ultimately producing weak binders. Refining our phage display libraries to include reversible covalent warheads allowed for the identification of more potent lipid reporters. In doing so, we have created the tools necessary to interrogate the unique resistance mechanisms expressed by these drug-resistant pathogens. A strong correlation was observed between peptides binding mcr-1 positive strains, LPS modification on the surface of these bacteria, and level of colistin resistance. To our knowledge, these peptides are the only probes capable of demonstrating this correlation. We surmise that the methods discussed here will pave the way for better diagnostic tools for these resistant pathogens. A recurring method of resistance among gram-positive and gram-negative bacteria has been to decorate their surface with positive amines to repel cationic antimicrobial peptides. As such, our current APBA library and the libraries in development in the Gao lab would be ideally suited to target these and other undiscovered resistance mechanisms. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
5

Determinantes emergentes de resistência antimicrobiana em Escherichia coli de origem clínica, fecal e de carne de aves e suínos / Emerging antimicrobial resistance determinants in poultry and swineEscherichia coli isolates from clinical, fecal and meat sources.

Cunha, Marcos Paulo Vieira 23 August 2018 (has links)
As grandes quantidades de antimicrobianos utilizados na produção de aves e suínos é um problema de saúde pública em todo mundo. O surgimento e disseminação de novos mecanismos de resistência a antibióticos de importância clínica em medicina humana e veterinária é fato que tem apontado a entrada de uma era \"pós-antibióticos\". Considerando a importância da avicultura e suinocultura na economia brasileira e os riscos para saúde humana e dos animais, o objetivo deste estudo foi determinar a ocorrência de genes emergentes de resistência aos antibióticos das classes dos β-lactâmicos, quinolonas, fosfomicina e colistina. Foram selecionados 1.152 isolados de Escherichia coli de origem clínica, fecal e de carne de suínos, frangos de corte, poedeiras e perus proveniente dos principais estados produtores e exportadores do Brasil (SP, RS, SC, PR, MG e GO). Através de métodos clássicos de biologia molecular e sequenciamento do genoma completo foi realizada a caracterização genotípica dos isolados, assim como a caracterização dos elementos genéticos móveis que carreavam esses genes. Dentre os isolados de aves (n=773), 103 (13,4%) foram produtores de ESBL: CTX-M-2 (n=61); CTX-M-55 (n=26); CTX-M-8 (n=12); CTX-M-2 + CTX-M-55 (n=3); CTX-M-2+CTX-M-8 (n=1); CTX-M-8+CTX-M-55 (n=1). 44 (5,7%) apresentaram CMY-2, presente em plasmídeos IncI1/ST12 e IncK. Em relação à resistência às quinolonas e colistina mediada por plasmídeos, os genes encontrados foram qnrA1 (1%), qnrB19 (6%) e qnrS1 (0,8%), além de 41 isolados positivos para mcr-1. A ocorrência de genes plasmidiais de resistência à fosfomicina ( fosA3) foi de 3,4%, que estiveram relacionados a plasmídeos epidêmicos IncN/F33:A-:B-. Dentre os isolados de E. coli patogênicas (ETEC, STEC), comensais e de carne de suínos ( n =378) foi encontrada uma alta prevalência de cepas positivas para mcr-1 (33,8%). Foram encontrados três isolados positivos para mcr-3 dentre os isolados de ETEC e comensais. O gene qnrS1 também teve alta prevalência (24,6%). Nos isolados de aves e suínos, o gene mcr-1 esteve presente em plasmídeos IncX4. Análises da sequência completa de DNA de vários plasmídeos mostrou relação com plasmídeos que circulam em criações animais na Ásia. Este estudo contribui para o estabelecimento de um cenário em relação à resistência antimicrobiana na produção animal no Brasil. Levando em conta que o Brasil está entre os maiores exportadores de carne de aves e suínos do mundo, é urgente a elaboração de estratégias para o controle da disseminação de bactérias resistentes a antibióticos clinicamente importantes. / The large amounts of antimicrobials used in the poultry and swine production is a public health concern worldwide. The emergence and spread of novel resistance mechanisms to important antibiotics in human and veterinary medicine is a fact that has pointed to entry into a \"post-antibiotic\" era. Considering the importance of poultry and pig farming in the Brazilian economy and the risks to human and animal health, the aim of this study was to determine the occurrence of emerging resistance genes to β-lactam, quinolones, fosfomycin and colistin antibiotics. A total of 1.152 of clinical, fecal and retail meat isolates of Escherichia coli from from swine, broilers, laying hens and turkeys from the main producing and exporting states of Brazil (SP, RS, SC, PR, MG and GO) were selected. Through classical molecular biology methods and whole genome sequencing, the characterization of the isolates was performed, as well as the characterization of the mobile genetic elements that carried these genes. Among avian isolates (n = 773), 103 (13.4%) were ESBL-producers: CTX-M-2 (n = 61); CTX-M-55 (n = 26); CTX-M-8 (n = 12); CTX-M-2 + CTX-M-55 (n = 3); CTX-M-2 + CTX-M-8 (n = 1); CTX-M-8 + CTX-M-55 (n = 1). 44 (5.7%) showed pAmpC CMY-2, present in IncI1/ST12 and IncK plasmids. An isolate belonging to ST117 harboring bla CMY2 and bla CTX-M-2 integrated into the chromosome. Regarding plasmid-mediated resistance to quinolones and colistin, the genes found were qnrA1 (1%), qnrB19 (6%) and qnrS1 (0.8%), in addition to 41 mcr-1 positive isolates. The occurrence of plasmid-mediated fosfomycin resistance ( fosA3) was 3.4%, which were related to the IncN/F33: A-: B- epidemic plasmids. A high prevalence of mcr-1 positive strains (33.8%) was found among pathogenic (ETEC, STEC) and commensal porcine E. coli isolates (n = 378). Three mcr-3 positive isolates were found among the ETEC and commensal isolates. The qnrS1 gene also had a high prevalence (24.6%). In avian and porcine isolates, the mcr-1 gene was present in IncX4 plasmids. Analyzes of the complete DNA sequence of various plasmids showed relation to plasmids circulating in animal production in Asia. This study contributes to the determination of a national scenario of antimicrobial resistance in animal production in Brazil. Taking into account that Brazil is among the largest exporters of poultry and pork in the world, it is urgent to devise strategies to control the spread of multidrug resistant bacteria to clinically important antibiotics.
6

Recherche de bactéries multi résistantes dans les fèces des animaux du bassin méditerranéen / Research of multi drug resistant zoonotic bacteria in feces of animals from Mediterranean area

Chabou, Selma 05 July 2018 (has links)
Notre travail de thèse a porté sur la recherche des bactéries multirésistantes zoonotiques dans les fèces des animaux du bassin méditerranéen, région pour laquelle peu de données sont disponibles. Cette thèse s’articule autour de quatre objectifs principaux ; (1) épidémiologie et prévalence des bactéries productrices de β-lactamases et de carbapénèmases chez les poulets d’Algérie, (2) étude et détection de la résistance plasmidique à la colistine chez les animaux d’Algérie, (3) recherche de vecteur et/ou réservoirs de bactéries zoonotiques résistantes à la colistine, (4) épidémiologie des bactéries résistantes à la colistine chez les humains en France, au Laos et au Liban. A travers ces investigations nous avons montré l’émergence et la dissémination du gène mcr-1 chez les animaux (poulets et caprins) dans plusieurs sites en Algérie. Nous avons également rapporté la détection de souches résistantes à la colistine dans des isolats humains en France et au Liban. Ces travaux ont participé à la description de l’épidémiologie du gène mcr-1 dans le monde chez les animaux et les humains et soulèvent la question du devenir de l’usage de la colistine chez l’homme et l’animal. Pour faire face à ces risques, nous pensons que des mesures de restriction d’usage des antibiotiques (y compris de la colistine) chez les animaux doivent s’appliquer, notamment en Algérie, pour limiter la propagation de ces gènes de résistance à l’homme. Il apparait donc nécessaire et urgent de mettre en place des enquêtes de surveillance de l’usage des antibiotiques chez les animaux notamment en Algérie pour éviter la propagation de souches résistantes chez l’homme. / This thesis is divided into 6 chapters with four objectives; (1) the epidemiology and prevalence of β-lactamases in chickens from Algeria, (2) contribution to the study and detection of plasmid resistance to colistin in animals from Algeria, (3) vectors/ reservoirs of zoonotic bacteria resistant to colistin, and (4) Epidemiology of bacteria resistant to colistin in humans in France, Laos and Lebanon.Throughout these investigations, we can conclude that there is an emergence and spread of mcr-1 in animals (chickens and goats) in several sites in Algeria. We also noted the detection of colistin-resistant bacteria in human isolates in France and in Lebanon. This indicates a spread of mcr-1 and colistin resistance genes worldwide in animals and humans and raises the question on the colistin usage in animals. To prevent this end, we believe that restrictions on the use of antibiotics (including colistin) should be applied, particularly in Algeria, to limit the spread of these resistance genes. Use control of colistin should be routinely performed in humans and animals through colistin resistance surveys in animals and humans.
7

Multi drug resistant organisms in Lebanese livestock / Etude des organismes multirésistants dans le bétail libanais

Dandachi, Iman 05 July 2018 (has links)
De nos jours, l'épidémiologie des bactéries multi-résistantes a évolué et ne se limite plus aux milieux hospitaliers. En effet, les animaux sont désormais considérés comme d’importants réservoirs de bactéries multi-résistantes, notamment des Bacilles à Gram négatif sécréteurs de bêta-lactamases et/ou résistant à la colistine. L'émergence de ces bactéries chez les animaux est due principalement à l’utilisation excessive d’antibiotiques en tant que prophylaxie et facteurs de croissance. Le transfert d’organismes multi-résistants aux antibiotiques provenant d’animaux vers les humains est un problème majeur pouvant entrainer de graves infections. La transmission zoonotique se fait par contact direct/indirect mais aussi par voie environnementale. Au Liban, plusieurs études ont été menées dans les hôpitaux et ont montré une prévalence élevée de bactéries multi-résistantes. En revanche, ces études sont rares dans le milieu vétérinaire. Le but de ce travail de thèse est de décrire l'épidémiologie des organismes multi-résistants dans les animaux d’élevage destinés à la consommation au Liban. Le typage des bactéries par MLST et le séquençage du génome entier ont été utilisés pour décrire la prévalence des organismes multi-résistants et les mécanismes de résistance chez les souches isolées. Nous pouvons ainsi conclure que les élevages de poulets et de porcs sont de puissants réservoirs de gènes de résistance BLSE et mcr-1 au Liban. La dissémination de la résistance semble être polyclonale et liée à la propagation de plasmides porteurs de gènes de résistance. Par conséquent, l'utilisation de la colistine en médecine vétérinaire au Liban doit être interdite. / Nowadays, the epidemiology of multi-drug resistance has changed and is no more confined to the hospital settings. Food producing animals are increasingly regarded as potent reservoirs of multi-drug resistant organisms i.e. beta lactamase producers and colistin-resistant Gram-negative bacilli. The emergence of multi-drug resistance in animals is thought to be mainly driven by the overuse of antibiotics as growth promoters and prophylaxis. The dissemination of resistant organisms in animals is sparked by the concern of being transferred to humans where they can be candidates for infections with limited therapeutic options. The zoonotic transmission of resistant organisms from animals to humans occurs mainly via direct/indirect contact but also via environmental routes. In Lebanon, several studies were conducted in hospitals and showed a high prevalence of multi-drug resistance; unlikely, these studies are scarce in animals. The aim of this thesis research was thus to describe the epidemiology of multi-drug resistant organisms in Lebanese Livestock Multi-locus sequence typing and whole genome sequencing were used to describe the prevalence of multi-drug resistant organisms and the corresponding mechanisms of resistance in the isolated strains from chicken, pigs, farmers and environment. Chicken and swine farms showed to be potent reservoirs of ESBL and mcr-1 genes in Lebanon. The dissemination of multi-drug resistance appears to be multi-clonal and related to the spread of plasmid carrying resistance genes. Colistin use in veterinary medicine in Lebanon should be banned.
8

Analytical methodologies based on chemometrics to optimize the photodegradation of dyes

Fernández Barrat, Cristina 23 January 2012 (has links)
El objeto de la presente tesis es el desarrollo de metodologías analíticas rápidas para optimizar los procesos de degradación de colorantes orgánicos presentes en aguas residuales. Se ha llevado a cabo una revisión bibliográfica acerca de dichos procesos y las técnicas analíticas utilizadas para su monitorización y la identificación de posibles intermedios. Se han establecido nuevas metodologías analíticas basadas en herramientas quimiométricas tales como diseño de experimentos para optimizar procesos de fotodegradación con y sin catalizador. Se ha empleado resolución de curvas multivariante para la determinación simultánea de colorantes e intermedios durante estos procesos. Dado que la velocidad de degradación es el parámetro mas utilizado para evaluar la eficiencia de las fotodegradaciones se han evaluado todas las constantes involucradas en la degradación y/o la adsorción sobre el catalizador mediante HS-MCR-ALS. Se ha establecido una metodología analítica rápida para la determinación de colorantes basada en cromatografía de inyección secuencial (SIC). / The main aim of this thesis is the development of rapid analytical methodologies to optimize the photodegradation processes of organic azo dyes from industrial wastewater. A bibliographic review has been done concerning the most employed processes for dye removal and the analytical techniques used for the monitoring and the identification of intermediates. New analytical methodologies based on chemometric tools such as experimental designs have been established to optimize photodegradation processes with and without using heterogeneous catalysts. Multivariate curve resolution has been employed to determine simultaneously different dyes and intermediates along degradation processes. Since the degradation rate is the most employed parameter to evaluate the photodegradation efficiency all the kinetic constants involved in the degradation and/or the adsorption of the dye onto the catalyst have been evaluated by HS-MCR-ALS. Furthermore a rapid analytical methodology for dye determination based on sequential injection chromatography (SIC) has been established.
9

Espectroscopia Raman amplificada por superfície em aplicações analíticas assistidas por ferramentas quimiométricas / Chemometric-assisted analytical applications using surface-enhanced Raman spectroscopy

Mamián López, Mónica Benicia, 1978- 12 December 2013 (has links)
Orientador: Ronei Jesus Poppi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-24T17:49:24Z (GMT). No. of bitstreams: 1 MamianLopez_MonicaBenicia_D.pdf: 23169913 bytes, checksum: cf40556e2a6f09ccb3f2b2bf36b0b234 (MD5) Previous issue date: 2014 / Resumo: Foi utilizada a espectroscopia Raman amplificada por superfície SERS, em conjunto com ferramentas quimiométricas de resolução de curvas e alguns algoritmos complementares, em quatro aplicações analíticas que incluíram imagem SERS, monitoramento de um sistema dinâmico multicomponente e quantificação de nicotina e moxifloxacina em urina. Como intensificadores do sinal foram empregados um sistema coloidal de ouro, sintetizado segundo o método de Lee-Miesel e um substrato sólido comercial de ouro nanoestruturado / Abstract: In this work, four chemometric-assisted analytical procedures using surface-enhanced Raman spectroscopy are proposed. A multivariate curve resolution method in conjuction with others algorithms were employed to quantify the alkalloid nicotine in presence of two related compounds; determinate the antibiotic moxifloxacin in urine and to study its photolyitic degradation. Besides, SERS imaging was applied to study the paracetamol distribution in polymeric films. As SERS enhancers were used colloidal gold and a nanostructured gold substrate / Doutorado / Quimica Analitica / Doutora em Ciências
10

Caracterização de biodiesel e misturas BXX por GCxGC-FID e GCxGC qMS / Characterization of biodiesel and mixtures of BXX GCxGC-FID and GCxGC qMS

Mogollón, Noroska Gabriela Salazar, 1986- 21 August 2018 (has links)
Orientadores: Fabio Augusto, Ronei Jesus Poppi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T16:37:50Z (GMT). No. of bitstreams: 1 Mogollon_NoroskaGabrielaSalazar_M.pdf: 3540897 bytes, checksum: 1c33a87e76ee946114306b0838e6978b (MD5) Previous issue date: 2012 / Resumo: Neste trabalho,foram aplicadas metodologias quimiométricas para a caracterização de biodieseis de diversas origens, junto à sua quantificação em misturas BXX (biodiesel em diesel mineral), por meio de dados fornecidos por GC×GC-FID, com uma alta capacidade de separação e detectabilidade, em conjunto com algoritmos de classificação e de resolução de curvas para quantificação de misturas complexas. Primeiramente, foram otimizadas as condições de trabalho aplicadas no preparo de biodiesel, escolhendo-se em seguida o melhor conjunto de colunas que separou os ésteres metílicos provenientes do biodiesel. Foram analisadas amostras de biodieseis de soja com tempos de envelhecimento diferentes nos distintos conjuntos de colunas. Com os dados fornecidos, foi aplicado o algoritmo de classificação analise de componente principal multimodo (MPCA), observando-se a separação entre os biodieseis de óleo de soja novo e envelhecido e, com tais dados, escolheu-se o conjunto que melhor executou a classificação. Em seguida, foram analisadas amostras de biodieseis de diferentes matérias primas, realizando-se a classificação dos mesmos pelo MPCA, observando-se os compostos responsáveis pela diferença entre os mesmos, também identificados por GC×GC-qMS. Finalmente, para a quantificação, foi construída uma curva de calibração analítica com misturas BXX de biodiesel de óleo de soja novo, e para a validação da curva, utilizaram-se biodieseis de diferentes matérias primas, desprezando-se os compostos que diferiram nas diferentes amostras, resultando em um algoritmo útil para quantificar misturas BXX com biodieseis de qualquer fonte / Abstract: Chemometric methods were applied for characterization of biodiesel from different origins, along with their quantification in mixtures BXX (biodiesel in mineral diesel) through data collected from GCxGC-FID. This takes advantage of the high separation capacity and the detectability of the two-dimensional system along with classification algorithms and curve resolution for complex mixture quantification. And the first step, the working conditions for preparing biodiesel were optimized, taking the best set of columns that separated the methyl esters from the biodiesel. Samples of soybean oil biodiesel were analyzed with different aging times in different sets of columns. With the data obtained, the MPCA classification algorithm was applied. Observing the separation between the biodiesels, the data was used for picking the best set of columns for the execution of the classification. Next, biodiesel samples from different raw materials were analysis, performing their classifications by MPCA, observing the compounds responsible for the difference between the biodiesels. These were also identified by GCxGC-qMS. Finally for quantification, a calibration curve with BXX mixtures of new soybean oil biodiesel was constructed for validation. Using biodiesel made out of different raw materials from various sources, ignoring compounds that differ in the biodiesel, a useful algorithm to quantify biodiesel blends BXX with any raw material was obtained / Mestrado / Quimica Analitica / Mestra em Química

Page generated in 0.0302 seconds