Abstract The aim of this investigation was to assess the effects of gamma radiation on nanocomposite films (NC films) formed by PCL (polycaprolactone) with MCM-48 nanoparticles (PCL/MCM-48) and PCL with MCM-48 NPs modified with (3-aminopropyl)triethoxysilane (APTES) (PCL/MCM-48-NH2). The nanocomposite films were obtained using the solvent casting method. After preparing the films, they were irradiated at 25 kGy in the presence of air and analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), transmission electronic microscopy (TEM), as well as for their mechanical properties. The exposure of NC films to gamma radiation at 25 kGy did not cause major changes in either thermal or mechanical properties such as tensile strength and modulus of elasticity. The results revealed that gamma radiation was a successful choice for the sterilization of these materials.

The production of fatty acid methyl esther (FAME) via transesterification was studied, assessing the influence of CaO heterogeneous catalysts obtained from four different fishery residues: sururu, crab, clam and mussel. Characterization and properties of the residues were obtained via thermogravimetric analysis, X-ray diffraction, X-ray fluorescence, Fourier transform infrared (FTIR) spectra, nitrogen adsorption/desorption, chemical composition and scanning electron microscopy (SEM). Catalytic activities and reaction kinetics of FAME synthesis from the transesterification of soybean oil were performed. FAME yield was determined by 1H nuclear magnetic resonance (NMR). A higher efficiency and reaction rate were observed for the catalysts obtained from the sururu residues with 93.7% FAME yield after 3.5 h of reaction at the first usage, reducing only to 91.0% after four consecutive cycles of reuse. The best activities were assigned to the presence of SrO, to smaller particle size, higher pore volumes and the higher Ca leaching, yielding Ca-diglyceroxide which is an important active phase for transesterification.

RESUMO Matrizes de hidroxiapatita (HAp) dopadas com os íons lantanídeos Eu3+, Ce3+ e Gd3+, [Ca10-xLnx(PO4)6(OH)2], foram obtidas pelo método da precipitação com o objetivo de estudar suas propriedades fotofísicas. A partir de análises de Microscopia Eletrônica de Varredura observou-se que amostras dopadas com íons lantanídeos (Ln3+) apresentaram similaridade com a morfologia da HAp pura, por outro lado nos difratogramas de Raios X a partir do refinamento Rietveld verificou-se que a matriz aparece como fase majoritária (≈ 70%) enquanto (≈ 30%) de uma fase secundária de tricálcio fosfato (TCP) foi conferida em função das diferentes dopagens. Isotermas de adsorção obtidas pela técnica BET indicaram que todos os materiais sintetizados são classificados como mesoporosos. Os espectros de emissão dos materiais exibem bandas características dos íons Ln3+ incorporados à estrutura da matriz em 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), e 698 nm (5D0→F4) para HAp/Eu, 337-360 nm (5d→4f) para HAp/Ce e em 425 nm para HAp/Gd.

ABSTRACT Hydroxyapatite (HAp) matrices doped with lanthanide ions Eu3+, Ce3+ and Gd3+, [Ca10-xLnx(PO4)6(OH)2] were obtained through the precipitation method so their photophysical properties could be studied. From the Scanning Electron Microscopy analyzes it was observed that samples doped with lanthanide ions (Ln3+) showed similarity with the morphology of pure HAp, whereas Rietveld-refined X-ray diffractograms showed that the matrix appears as the major phase (≈70%) while (≈30%) of a second phase of tricalcium phosphate (TCP) was due to the different doping levels. Adsorption isotherms obtained by the BET technique indicated that all the synthesized materials are classified as mesoporous. The emission spectra of the materials exhibit bands typical of the Ln3+ ions incorporated into the matrix structure at 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), and 698 nm (5D0 → F4) for HAp/Eu, 337-360 nm (5d → 4f) for HAp/Ce and at 425 nm for HAp/Gd.

Neste trabalho, ferramentas teóricas foram utilizadas no estudo de propriedades espectroscópicas do conjugado microcistina-LR-criptato de európio. O modelo Sparkle/AM1 foi aplicado na previsão da geometria do sistema e o modelo INDO/S-CIS foi utilizado no cálculo das energias dos estados excitados. Os parâmetros de Intensidade foram previstos baseados na teoria Judd-Ofelt e o modelo teórico baseado na teoria das transições 4f-4f foi aplicado no cálculo das taxas de transferência e de retrotransferência de energia, taxas de decaimento radiativo e não radiativo, eficiência e rendimento quânticos. Um estudo detalhado das propriedades luminescentes do conjugado microcistina-LR-criptato de európio foi realizado. Os resultados mostram que o rendimento quântico teórico de 23% está em bom acordo com valores experimentais publicados. Este fato sugere que este protocolo teórico pode ser usado para a concepção de novos sistemas objetivando melhorar as propriedades luminescentes. Os resultados sugerem que este sistema luminescente pode ser um bom conjugado para ser usado no teste ELISA para detecção por fluorescência da microcistina-LR em água.

In this work, theoretical tools were used to study spectroscopic properties of the conjugate microcystin-LR-europium cryptate. The Sparkle/AM1 model was applied to predict the geometry of the system and the INDO/S-CIS model was used to calculate the excited state energies. Based on the Judd-Ofelt theory, the intensity parameters were predicted and a theoretical model based on the theory of the 4f-4f transitions was applied to calculate energy transfer and backtransfer rates, radiative and non-radiative decay rates, quantum efficiency and quantum yield. A detailed study of the luminescent properties of the conjugate Microcystin-LR-europium cryptate was carried out. The results show that the theoretical quantum yield of luminescence of 23% is in good agreement with the experimental value published. This fact suggests that this theoretical protocol can be used to design new systems in order to improve their luminescence properties. The results suggest that this luminescent system may be a good conjugate for using in assay ELISA for detection by luminescence of the Microcystin-LR in water.