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Aspectos fisiológicos do fruto de açaí sob armazenamento refrigerado
(Universidade Federal de São Carlos, 2010-08-10) Stefanini, Thais França; Pessoa, José Dalton Cruz; https://lattes.cnpq.br/4212703554284544; https://lattes.cnpq.br/6293022488155409
The açaí berry market has been increasing due to its high calorie characteristic and antioxidant activity, that contributes to diseases prevention. The market growth makes it the center of attention, upcoming the necessity to study its storage, transportation and processing chain. So this study has the objective to analyze the physiology and storage conditions of the açaí berry through measures of respiration, based on temperature and water content, freezing point detection, water potential due to water content function, cohesion of the mesocarp, color of the parenchymal reserve, pH level, acidity and contents of anthocyanins. The respiration based on the temperature of the açaí berry can be fitted by Arrhenius curve with activation energy of 79.6 kJ.mol-1. Q10 values for the açaí berry were between 2 and 3.The metabolism of the açaí berry showed and exponential result related to the reduction in water content. The average freezing temperature was around -3.4 º C, and maximum of -1.8 ° C. The hidroconservation storage reduces oxidation of anthocyanins, due to its low temperature. However, fruits stored in hidroconservation showed possible characteristics of freezing injury and anaerobic conditions, indicated by the presence of aqueous solution produced by the fruit inside the package, reducing the mesocarp cohesive force, changing the parenchyma s reserves colour and acidity variations. The refrigerator storage leads to a fast decrease in total anthocyanins. The gas permeability of the used packaging process reduces the anaerobic process, and its higher storage temperature decreases the symptoms of freezing injury, but increases fruit water loss.
Fotoluminescência de nanopartículas de Ni(OH)2 e avaliação catalítica de NiO na redução de NO com CO
(Universidade Federal de São Carlos, 2010-08-10) Moura, Ana Paula de; Longo, Elson; https://lattes.cnpq.br/9848311210578810; https://lattes.cnpq.br/5657905412702016
In recent years, nanostructured oxides have attracted great interest from different areas of technology due to the possibility of developing new devices or electro-optical equipment. In principle, the physical and chemical properties of these compounds are governed by the distribution, shape and size of their particles. Currently, conventional hydrothermal methods have enabled the training of various oxides with different morphologies and degree of crystallinity, with the use of low temperature synthesis or processing (> 200 oC). Moreover, the main disadvantage of these systems lies in their long treatment times, which was circumvented by the use of microwave radiation as the heating source. This new equipment has become known as microwave hydrothermal (MH). So in this work, nickel hydroxide (Ni (OH) 2) was synthesized by hydrothermal microwave in the presence of cetyl trimethyl ammonium (CTAB) and polyethylene glycol (PEG). Also, these summaries were analyzed the influence of different chemical bases (ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH)) and the effect of hydrothermal treatment times. The nickel oxide was obtained through the thermal decomposition of precursor (Ni(OH)2) previously formed. For this we used thermal treatment temperature of 300 oC and 500 oC in a microwave oven for a period of 2 min. These samples were investigated by X-ray diffraction (XRD), infrared analysis (FTIR) spectroscopy, micro-Raman (MR) scanning electron microscope by field emission gun high resolution (FEG-SEM), electron microscopy transmission (TEM) and reduction with hydrogen temperature programmed (TPR-H2). The optical properties were studied by ultraviolet-visible spectroscopy (UV-vis) and photoluminescence measurements. The X-ray diffraction showed that both Ni(OH)2 and NiO have a high degree of crystallinity and are structurally ordered at long range. The FTIR spectra and MR exhibited characteristic bands for these materials. The microscopy images of FEG-MEV and TEM indicate the formation of plaques with irregular shapes, nature and agglomerated nanometric dimensions. The UV-vis spectra suggested the existence of intermediate energy levels within the band gap. When excited with a Tese de doutorado Ana Paula de Moura VI wavelength of 350 nm, Ni(OH)2 showed a broadband emission photoluminescence in the blue and also red in the visible spectrum. RTP-H2 curves for NiO showed the presence of peaks on the reduction of Ni2 + to nickel metal. The samples showed catalytic properties of NiO on the reaction of CO / NO.