Made available in DSpace on 2017-07-24T19:22:22Z (GMT). No. of bitstreams: 1 Sandracr.pdf: 955996 bytes, checksum: 8d2e096cd1c87011d908615d47978334 (MD5) Previous issue date: 2006-02-16 / The aim of this study was to evaluate the quantity of residual monomers of a microhibrid composite resin, photocured with different types of light curing units: halogen and LEDs based on different times of photopolymerization (10, 20 and 40 seconds). Samples of the composite resin were made with Teflon bipartite matrix with a center hole of 6 mm diameter compatible with the tips of the light curing units. The distance of the light guide curing unit to the composite samples was 4 mm. The average a width of the samples Charisma® composite resin color A2 and SL were 2 mm. The curing units used were Optilux 401 (Demetron) and Optilight LD III (Gnatus). The materials were prepared and weighed on an accuracy scale and stored in solvent, in the dark, at room temperature for 24 hours. The solvent used to separate the organic and inorganic load was chloroform thirty six samples were made, stored in chloroform and analysed with infrared spectroscopy (FTIR) and the presence of carbon double bonds were found. Another solvent investigated in this study was methanol, because it is considered an efficient solvent for extracting present monomers in the resin, with an advantage because it acts as an inhibitor in this type of polymerization while maintaining the characteristic of the sample for quantitative analysis. Parallel to that, one hundred new samples were made. They were appropriately stored in methanol and analysed with UV- visible light spectroscopy (UV-Vis), through observance spectrum. The collected data was analysed in Origin 5.0 programs at the peak of observance in the same wavelength. The percentage of residual monomers was analysed by ANOVA and Games Howell tests. The results indicated that Charisma® composite resin color A2 showed less residual monomers. The halogen and LEDs light cure units showed the same percentage of residual monomers results, or rather, it showed a larger conversion of monomers in polymers. The LED based system promoted a smaller conversion degree compared to halogen light. The 10, 20 and 40 seconds of photocured presented the same quantity of residual monomers. / Neste trabalho foi avaliada a quantidade de monômeros residuais de uma resina composta micro-híbrida de duas cores, com dois aparelhos: halógena e outro à base de LEDs, em três tempos de fotoativação (10, 20 e 40 s). Para a confecção dos corpos-de-prova foi utilizada uma matriz bipartida de teflon com orifício central de 6 mm de diâmetro, compatível com as pontas dos equipamentos fotoativadores. A distância da ponta ativa do fotopolimerizador aos corpos-de-prova foi de 4 mm. A espessura média dos corpos-de-prova de resina composta Charisma® (Heraeus Kulzer) cor A2 e SL foi de 2 mm. Os aparelhos utilizados foram: lâmpada halógena Optilux 401 (Demetron) e Optilight LD III (Gnatus), à base de LEDs. Os materiais foram preparados e pesados em balança analítica e armazenados durante 24 horas em solventes ao abrigo da luz e à temperatura ambiente. O solvente utilizado para separar a fração orgânica das partículas inorgânicas foi o clorofórmio. Foram confeccionados 36 corpos-de-prova armazenados em clorofórmio e analisados em espectrômetro de infravermelho (FTIR) e foi verificada a presença das ligações duplas de carbono-carbono. Outro solvente utilizado neste experimento foi o metanol, por ser um solvente eficiente para a extração dos monômeros presentes na resina, com a vantagem de agir como inibidor deste tipo de polimerização, preservando as características da amostra para a análise quantitativa. Paralelamente foram confeccionados 120 corpos-de-prova devidamente armazenados em metanol e analisados em espectrômetro de ultravioleta-visível (UVVis) ou equipamento de espectrometria na região do ultravioleta-visível, através de espectros de absorvância. A leitura e interpretação dos dados obtidos foram feitos no programa Origin 5,0 nos picos de maior absorvância (%A) no mesmo comprimento de onda (nm). A porcentagem de monômeros residuais foi analisada pelo teste de Variância e teste de Games Howel. Os resultados evidenciaram que a resina composta Charisma® cor SL apresentou uma menor quantidade de monômero residual, ou seja, apresentou uma maior conversão de monômeros em polímeros. O sistema à base de LEDs promoveu um menor grau de conversão comparado a lâmpada halógena. Os tempos de 10, 20 e 40 s de fotoativação proporcionaram a mesma quantidade de monômeros residuais.

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 FranciscoFN_DISSERT.pdf: 2089554 bytes, checksum: 7f494e90c450d766696575e9a76682d2 (MD5) Previous issue date: 2012-02-29 / Universidade Federal do Rio Grande do Norte / This work is combined with the potential of the technique of near infrared spectroscopy - NIR and chemometrics order to determine the content of diclofenac tablets, without destruction of the sample, to which was used as the reference method, ultraviolet spectroscopy, which is one of the official methods. In the construction of multivariate calibration models has been studied several types of pre-processing of NIR spectral data, such as scatter correction, first derivative. The regression method used in the construction of calibration models is the PLS (partial least squares) using NIR spectroscopic data of a set of 90 tablets were divided into two sets (calibration and prediction). 54 were used in the calibration samples and the prediction was used 36, since the calibration method used was crossvalidation method (full cross-validation) that eliminates the need for a validation set. The evaluation of the models was done by observing the values of correlation coefficient R 2 and RMSEC mean square error (calibration error) and RMSEP (forecast error). As the forecast values estimated for the remaining 36 samples, which the results were consistent with the values obtained by UV spectroscopy / Neste trabalho s?o combinadas as potencialidades da t?cnica de espectroscopia no infravermelho pr?ximo NIR e da quimiometria visando ? determina??o do teor de diclofenaco em comprimidos, sem destrui??o da amostra, para o qual utilizou-se como refer?ncia o m?todo de espectroscopia no ultravioleta, que ? um dos m?todos oficiais. Na constru??o dos modelos de calibra??o multivariada estudou-se v?rios tipos de pr?processamento dos dados espectrais NIR, como corre??o do espalhamento da luz, primeira derivada. O m?todo de regress?o usado na constru??o dos modelos de calibra??o foi o PLS (m?nimos quadrados parciais) utilizando dados espectrosc?picos do NIR de um conjunto de 90 comprimidos divididos em dois conjuntos (calibra??o e previs?o). Na calibra??o foram usadas 54 amostras e na previs?o foram usadas 36, uma vez que o m?todo de calibra??o utilizada foi o m?todo de valida??o cruzada (full cross validation) que dispensa a necessidade de um conjunto de valida??o. A avalia??o dos modelos foi feita observando os valores de coeficiente de correla??o R2 e os erros quadrados m?dios RMSEC (erro de calibra??o) e RMSEP (erro de previs?o). Sendo os valores de previs?o estimados para as demais 36 amostras, o qual os resultados se mostraram coerentes com os valores obtidos por espectroscopia no ultravioleta

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: N. Werstiuk. Includes bibliographical references (leaves 148-156). Also available via World Wide Web.

Thesis (Ph.D.)--Baylor University, 2009. / Includes bibliographical references (p. 184-195).

Warfarin is a well-known anticoagulant drug that is used to prevent cardiovascular disease and blood coagulation such as thrombosis. In this study, the main aim was to investigate the photo physical characteristics of warfarin in the different molecular environments provided by sodium dodecyl sulfate (SDS) micelles by using ultraviolet absorption and fluorescence emission spectroscopic techniques. Warfarin and a structural analogue not existing in solution as a cyclic hemiketal, phenprocoumon, were mixed with different concentrations of SDS and spectral changes for these warfarin and phenprocoumon were recorded. Interestingly, results demonstrated, based on an evident increase in the absorption intensity at 273 nm and an evident blue shift in the fluorescence emission spectrum after the addition of an increasing concentration of SDS, that primarily the cyclic hemiketal isomer of warfarin was found to be solvated by SDS micelles at an apparent recorded critical micelle concentration of ~8mM.  Altogether these observations suggest that warfarin may be used as a molecular probe to explore the polarities of complex colloidal mixtures. Moreover, the possibility of using micelles for controlling the isomeric state of warfarin is interesting and can potentially be used for better controlling dosage of warfarin thereby reducing side effects.