[pt] Corpos relativamente pequenos do sistema solar não possuem atmosfera (ou muito rarefeita, chamada exosfera) e nem campo magnético: encontram-se praticamente desprotegidos da influência do ambiente espacial no qual estão inseridos. Tais corpos (como a maioria dos asteroides, luas e cometas distantes do Sol), estão sujeitos aos efeitos do chamado intemperismo espacial. Com o objetivo de simular e estudar este fenômeno em laboratório, três amostras de meteoritos do tipo condrito ordinário foram irradiadas por feixes de H(positivo) com energia de 1,0 MeV. Uma das amostras foi, também, irradiada por feixe de N(positivo) de 2,0 MeV. Os efeitos da irradiação foram monitorados por espectroscopias Raman e UV-VIS-NIR. Os resultados Raman mostram variações sistemáticas do número de onda, da intensidade e da largura das bandas vibracionais estudadas, evidências de modificações estruturais. As seções de choque de destruição das ligações Si-O presentes nas estruturas cristalinas foram determinadas. A espectroscopia UV-VIS-NIR por refletância de esfera integrada foi usada para monitorar as modificações nas características espectrais. Os espectros obtidos mostram escurecimento e avermelhamento progressivos das amostras irradiadas; a amplitude destas modificações depende do conteúdo inicial de ferro na estrutura. É proposto que o avermelhamento observado com o aumento da fluência (ou dose) da irradiação deve-se ao aumento do coeficiente de absorção na faixa azul que, por sua vez, decorre da diminuição do gap óptico do material. Estes resultados são relevantes para a modelagem da evolução físico-química de asteroides expostos ao vento solar. / [en] Relatively small bodies in the solar system have no atmosphere (or very thin, called the exosphere) and no magnetic field: they are virtually unprotected from the influence of the space environment in which they are inserted. Such bodies (like most asteroids, moons, and comets far from the sun), are subject to the effects of so-called space weathering. To simulate and study this phenomenon in the laboratory, three samples of ordinary chondrite meteorites were irradiated by H(positive) beams with 1.0 MeV energy. One of the samples was also irradiated by a 2.0 MeV N(positive) beam. The effects of irradiation were monitored by Raman and UV-VIS-NIR spectroscopies. The Raman results show systematic variations in the wavenumber, intensity, and width of the studied vibrational bands, evidence of structural modifications. The shock sections of the destruction of Si-O bonds present in the crystalline structures were determined. Integrated sphere reflectance UV-VIS-NIR spectroscopy was used to monitor changes in spectral characteristics. The obtained spectra show progressive darkening and reddening of the irradiated samples; The extent of these modifications depends on the initial iron content in the structure. It is proposed that the redness observed with the increase of irradiation creep (or dose) is due to the increase in the absorption coefficient in the blue band, which, in turn, results from the decrease of the optical gap of the material. These results are relevant for modeling the physicochemical evolution of asteroids exposed to the solar Wind.

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Water extracts of saffron, a spice derived from the plant Crocus Sativus L. obtained from India and Iran, were analyzed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). The components in the extracts were separated on four different solid phase extraction cartridges with four different solvents and by silica gel column. Analysis was done by GC-MS, LC-MS and UV-Vis spectroscopy. The extracts separated into three distinct bands (two bright yellow and one orange) on the silica gel column. Based on GC-MS, the extracted compounds show many structural similarities. Using both extraction techniques, several compounds were identified that were not previously reported to be in saffron. Picrocrocin, safranal, and crocins presence in the extracts were evidenced by absorbance bands at wavelengths of 250 nm, 310 nm and 440 nm, respectively, in their UV-Vis spectra. The LC-MS analysis revealed several high molecular weight compounds that were not observed by GC-MS.

Made available in DSpace on 2017-07-24T19:38:00Z (GMT). No. of bitstreams: 1 Marilei Casturina.pdf: 1682032 bytes, checksum: 153b370b1eb7a1287824bf96aa0d0d65 (MD5) Previous issue date: 2008-11-17 / In this work is to porphyrin free base, cationic, meso-tetrapyridylporphyrin, TMPyP,and porphyrin metal, anion, zinc (II)-meso-Tetrakis (4-sulfonatophenyl), ZnTPPS4, in order to assess its possible applications in photodynamic therapy (PDT). For both, were investigated by molecular spectroscopy and UV-Vis, some properties of these porphyrins, such as interaction with biomimetic models, the ability to aggregate in different proportions water/ethanol, the photo-bleaching before lighting the red LEDs and generation of singlet oxygen through the test of uric acid. Microbiological tests were also conducted with Artemia salina and the bacterium Escherichia coli, to assess the in vitro photodynamic action on these microorganisms. The spectral behavior of porphyrin ZnTPPS4 was estimated to be varying the pH of the solution of porphyrin in aqueous medium and acetate/phosphate in the presence and absence of surfactant SDS (anion), CTAB (cationic) and HPS (zwiterionic). Through this analysis, we found that the porphyrin spectral change due to changes in pH, occurred at pHs lower when the porphyrin found himself in the presence of surfactants CTAB and HPS, indicating that there was interaction between porphyrin/ micelle surfactant, mediated by hydrophobic and electrostatic interactions. The ability of aggregation was evaluated by adding the solution of the porphyrin mixtures water/ethanol in different proportions in order to analyze the spectral behavior of both porphyrins with the increase of water content. Through this analysis it was found the displacement of the Soret band for a wavelength smaller, and the decrease in absorbance intensity of the condition of 100% water, a fact that may be related to different coefficients of molar absorptivity of porphyrins in solvents used. The photobleaching was putting itself and ethanol aqueous solutions of porphyrin under lighting of LEDs red during a total period of 1 hour, and showed that both porphyrins do not fall apart before the light source used. As the generation of singlet oxygen conducted through the test of uric acid, found that the generation of this species is better in water than ethanol, probably because there is more molecular oxygen dissolved in the first solvent. The porphyrin TMPyP showed increased photodynamic activity (PA) that ZnTPPS4, due to higher absorption in the range of issuing LEDs employees. Regarding microbiological tests found that the highest viewing on A. salina mortality occurs in the presence of porphyrin and under illumination, indicating photodynamic action of porphyrins on the microorganism. The testing done with E. coli, it is further inhibit the growth of this microorganism colonies where they were treated with porphyrins and light, compared with the controls: I) under light and without porphyrin; II) in the presence of porphyrin and no light; III) in the absence of light and porphyrin. / Neste trabalho estudou-se a porfirina base livre, catiônica, meso-tetrakis(4-metilpiridil)porfirina, TMPyP e a porfirina metalada, aniônica, Zinco(II)-mesotetrakis(4-sulfonatofenil), ZnTPPS4, para avaliar suas possíveis aplicações em terapia fotodinâmica (TFD). Para tanto, foram investigadas através de espectroscopia molecular UV-Vis, a interação das referidas porfirinas com modelos biomiméticos, a capacidade de agregação em diferentes proporções água/etanol, o foto-branqueamento perante iluminação de LEDs vermelhos e a geração de oxigênio singlete através do teste do ácido úrico. Também foram realizados testes com a Artemia salina e com a bactéria Escherichia coli, a fim de avaliar a ação fotodinâmica in vitro sobre esses microrganismos. O comportamento espectral da porfirina ZnTPPS4, foi avaliado variando-se o pH da solução de porfirina em meio aquoso e em acetato/fosfato na presença e na ausência dos surfactantes SDS (aniônico), CTAB (catiônico) e HPS (zwiteriônico). Através dessa análise, verificou-se que a mudança espectral da porfirina em decorrência da variação de pH, ocorreu em pHs menores quando a porfirina encontrou-se na presença dos surfactantes CTAB e HPS, indicando que houve interação entre porfirina/micela de surfactante, mediada por interações hidrofóbicas e eletrostáticas. A capacidade de agregação foi avaliada, acrescentando solução das porfirinas a misturas água/etanol de diferentes proporções, a fim de analisar o comportamento espectral de ambas as porfirinas com o aumento do teor de água. Através dessa análise verificou-se o deslocamento da banda Soret para comprimentos de onda menores, bem como, a diminuição da intensidade da absorbância em condição de 100% de água, fato que pode estar relacionado aos diferentes valores de coeficiente de absortividade molar das porfirinas nos solventes utilizados. A análise de foto-branqueamento foi realizado colocando-se soluções aquosas e etanólicas de porfirina sob iluminação de LEDs vermelhos durante um período total de 1 hora, e mostrou que ambas as porfirinas não se decompõem perante a fonte de luz empregada. Quanto a geração de oxigênio singlete realizado através do teste do ácido úrico, verificou-se que a geração dessa espécie é melhor em água que etanol. A porfirina TMPyP mostrou maior atividade fotodinâmica (AF) que a ZnTPPS4, por possuir maior absorção na faixa de emissão dos LEDs empregados. Em relação aos testes microbiológicos verificou-se que o maior índice de mortalidade sobre A. salina ocorre na presença das porfirina e sob iluminação, indicando ação fotodinâmica das porfirinas sobre esse microrganismo. No teste feito com a E. coli, evidenciou-se maior inibição no crescimento das colônias desse microrganismo quando as mesmas foram tratadas com porfirinas e luz, em comparação com os controles: I) sob luz e sem porfirina; II) na presença de porfirina e sem luz; III) na ausência de luz e porfirina.

Este trabalho apresenta a síntese de novos compostos fotoativos contendo os grupos uréia e tiouréia e suas potenciais aplicações como sensores de ânions. Os compostos sintetizados foram caracterizados pelas técnicas de FTIR, RMN de 1H e 13C, onde foi possível confirmar obtenção dos compostos. Os compostos obtidos apresentam absorção na região do ultravioleta com valores de extinção molar de acordo com as transições -*. Com objetivo de testar os novos compostos sintetizados como sensor de ânions foi realizado um estudo fotofísico na presença de diferentes ânions, sendo todos como sais de tetrabutilamônio. Esses testes também foram realizados utilizando o método de detecção visual e a espectroscopia de RMN 1H indicando que os compostos 32 e 33 apresentaram resposta colorimétrica após a adição de fluoreto. / This work presents the synthesis of novel photoactive compounds containing the urea and thiourea groups and its potential application as sensors for anions in solution. The synthesized compounds were characterized by FTIR, 1H and 13C NMR techniques. The compounds show absorption in the ultraviolet region with values of molar extinction accordingly to -* electronic transitions. In order to test the new compounds as optical sensors for anions, photophysical studies, as well as the method of visual detection and 1H NMR titration were performed in the presence of different anions as tetrabutylammonium salts. Fluoride could be successfully detected by UVVis and 1H NMR titration using compounds 32 and 33.

The replacement of artificial with natural dyes is one of the most challenging research fields in the food production area. Recent studies have shown that some frequently used synthetic colours, called the “Southampton 6 Colours” may be linked with hyperactivity in children. The purpose of this work is to analyse the degradation behaviour of black carrot, a natural, red dye commonly used for colouring food products, and subsequently improve its stability during heat and storage conditions. The stability of the black carrot mixture to heat exposure was investigated at a range of pH values by heat-treating aqueous solutions in a domestic oven at around 180oC to maintain the temperature at 100oC and the powdered material in a furnace at 180oC (typical baking conditions). 1H NMR (800 MHz) spectroscopy was used for the assignment of the aromatic chemical shifts of the black carrot mixture by overlaying them with the characterised 1H NMR chemical shifts of the individual components separated by RP-HPLC. Integration of high-resolution 1H NMR (800 MHz) spectra was used to follow the relative degradation of each of the components. Different procedures for the complexation of black carrot with metal oxides were developed, for which colourants of different colour shades were prepared. Spectroscopic techniques were used to follow the degradation of the complexes which were heat-treated at 180oC. Nano-scale investigation of the metal oxide powders was also carried out. The optimised colourants were tested on a bench scale and subsequently on an industrial scale in food pilot procedures. The successful complexes produced were found to be more heat stable compared to the commercial black carrot dye. The developed technologies are cheap and easy-to-produce methods to create intense heat and storage stable coloured pigments which can be used for the replacement of existing artificial dyes during food processing.

Density Functional Theory (DFT) and time-dependent Density Functional Theory (TD-DFT) are powerful tools for modeling orbital energy in conjugated molecules and have been useful tools for research in organic photovoltaics. In this work, DFT is first used to explain the red shift in the absorption spectrum and increased absorption observed in MEH-PPV. Initially, the modeling of the red-shift in the absorption peak of MEH-PPV is studied using Gaussian 03 software with the global hybrid functional B3LYP for exchange-correlation and the 6-31G basis set. DFT and TD-DFT are used to separately study the effects of polymer chain length, carbon-carbon double-bond stretching, and the polymer in solution vs. in gas space on red shift in absorption spectrum. Next, Gaussian 09 software and the same B3LYP functional and 6-31G basis set are used to study interchain and intrachain interactions of MEH-PPV in solution. The red shift in the absorption peaks for three MEH-PPV configurations (single-chain pentamer, two stacked pentamers, and decamer) are compared with experimental results for five different solvents (chloroform, toluene, xylene, dichloromethane, and chlorobenzene). This investigation indicates that inter-chain interactions dominate in “good” aromatic solvents as compared to “poor” non-aromatic solvents. The results suggest that inter-chain charge transfer interactions play a critical role in real solutions and inter-chain aggregation takes precedence over intra-chain aggregation in aromatic solvents. In the final section of the study, accurate values for the range-separation parameter (w) for three lengths of MEH-PPV polymer (trimer, tetramer, and pentamer) in five different solvents (chloroform, chlorobenzene, xylene, Tetrahydrofuran, and dichloromethane) are reported using the range-separated functionals wB97XD and CAM-B3LYP. Using these data, range separation parameters are predicted and used for longer polymer chains in chloroform solution. The differences in the range separation parameters for the different solvents is statistically significant and gives further insight into the polymer/solvent interaction.

The main aim of this thesis work is to investigate the electrical, optical and thermal impact characteristics of cobalt oxide doped antimony tin oxide (CoO-ATO) in the form of thin films and nanofiber membranes. CoO-ATO is a novel composite material that has the potential to be used as reinforced aircraft coatings, military garment coatings, or more specifically as an anti-reflective (AR) top coating for photovoltaic (PV) cells. This work will be critical in determining the effectiveness of using a CoO-ATO layer in these applications. Electrospun nanofibers and spin coated thin films consisting of a polymeric solution of CoO-ATO will be used. Thin films are created using spin coating techniques, and nanofiber membranes are created using an electrospinning technique. Polystyrene (PS) will be used as a solute, and chloroform as a solvent, to create the solution. It is hypothesized that coatings of this material will have improved optical characteristics as compared to traditional ATO coatings and minimum impact from thermal cycling making it a favorable candidate for PV cells. This work will do an electrical, optical and thermal cycling impact characterization of CoO-ATO thin films and nanofiber membranes for a doping range of x% CoO where x ranged from 0.2

Iron is an essential element for life. It is involved in a number of biological processes, including iron sulfur (Fe/S) cluster assembly and heme biosynthesis. However it is also potentially toxic due to its ability to induce formation of reactive oxygen species (ROS) via Fenton chemistry. Therefore its uptake, trafficking and utilization must be regulated to avoid its toxicological effect. It has been recently discovered that Fe/S cluster biosynthesis machinery plays a key role in the cellular iron regulation and its disruption leads to impaired iron regulation and iron accumulation within mitochondria. The iron accumulation resulted from impaired Fe/S cluster assembly in the eukaryotic model organism Saccharomyces cerevisiae (baker’s yeast) was studied. Various biophysical (e.g. Mössbauer, EPR, UV-vis spectroscopy) and biochemical (e.g. Western blots, PCR, enzyme activity assay, etc.) techniques were used to characterize the iron content in yeast mitochondria isolated from several mutants strains. In these mutants one of the proteins involved in Fe/S cluster biosynthesis (Yah1p and Atm1p) is mutated and iron regulation and metabolism are disrupted. By integrating the results obtained from these different methods, it was determined that excess iron accumulates in the mutant mitochondria as inorganic phosphate Fe(III) nano-particles exhibiting superparamagnetic behaviors. Oxygen is required for iron accumulation and nanoparticle formation. The Fe(III) nano-particles can be chemically reduced to Fe(II) then largely exported from the mitochondria. These biophysical and biochemical methods were also used to examine the iron distribution in whole yeast cells of the Aft1-1up strain in which iron regulon genes are constitutively activated and compared to that of Yah1p-depleted and wild type yeast. Constitutive activation of iron regulon genes does not alter the cellular iron distribution significantly. However disruption of Fe/S cluster assembly by Yah1p depletion causes dramatic cellular iron redistribution: the vacuolar iron is largely evacuated and most of the cellular iron probably precipitates in mitochondria as Fe(III) nanoparticles. The results provide novel insights into iron trafficking and possible signal communications between organelles within cells.

In der vorliegenden Arbeit wurde der Einfluß der Oberflächeneigenschaften der verwendeten oxidischen Katalysatoren mit sauren Oberflächenzentren, der Elektrophilie des oberflächengenerierten Carbeniums und der Nucleophilie des Nucleophils auf die Reaktivität carbokationischer Zwischenstufen bei heterogen induzierten Reaktionen untersucht. Dazu wurde die modifizierte Geschwindigkeitskonstante k´ der Reaktion von oberflächengeneriertem Triphenylmethylium mit Nucleophilen bestimmt. Es konnte gezeigt werden, daß der Wert für k´ mit zunehmender Acidität, ausgedrückt durch den a-Wert des Katalysators, mit abnehmendem pKR+ des oberflächengenerierten Carbeniums und mit zunehmender Nucleophilie N des Nucleophils ansteigt. Dies ließ den Schluß zu, daß Konzepte wie z.B. die pKR+-Skala, die für Carbeniumionen in Lösung entwickelt wurden, qualitativ auf oberflächengenerierte Carbeniumionen übertragbar sind. Die Umsetzungen von auf Alumosilikaten generiertem Styrylium mit Aromaten ergaben, daß der Anteil des 1,1-Diphenylethanderivats im Verhältnis zu den ebenfalls gebildeten Styroldimeren mit zunehmender Nucleophilie N des Aromats zunahm. Untersuchungen zur Struktur und Konzentration von oberflächengeneriertem Triphenylmethylium bei Verwendung unterschiedlicher Katalysatoren und Triphenylmethyliumprecursoren wurden mittels UV-Vis- sowie Emissionsspektroskopie durchgeführt. Dabei hatte der verwendete Triphenylmethyliumprecursor keinen, der zur Aktivierung des Precursors verwendete Katalysator jedoch Einfluß auf die Struktur des oberflächengenerierten Triphenylmethyliums. Daraus wurden Vorschläge zur Wechselwirkung des Triphenylmethyliumprecursors mit den aciden Oberflächenzentren des Katalysators entwickelt. Es konnte weiterhin gezeigt werden, daß die Triphenylmethyliumkonzentration auf der Oberfläche von Aerosil® 300 linear von der eingesetzten Masse und der damit korrespondierenden BET-Oberfläche abhängt. / The relative rate constant k´ (s-1m-2) of the surface mediated hydride transfer reaction of 1,4-cyclohexadiene towards triphenylmethylium is significantly dependend on the nature of the solid acid catalyst used. This hydride transfer reaction has been studied to be catalysed by various moderatly strong acid catalysts, e.g. silicas, aluminas, alumosilicates and titan dioxide particles. For the kinetic measurements the triphenylmethylium was generated by chemisorbing chloro triphenylmethane to the solid acid catalyst. The individual pseudo first order rate constant k (s-1) of the hydride transfer reaction increases linearly with the amount of the solid acid catalyst. k´ is then determined as quotient of k through the product of the used amount of the catalyst and its specific BET surface area. The k´ value was used as the reference parameter in order to quantify the catalytic activity of a solid acid.