RESUMO
In this work, we report for the very first time on the thermoluminescence (TL) and afterglow (AG) properties of Li2ZrO3. The ternary oxide Li2ZrO3 was synthesized by solid state reaction of a mixture of Li2CO3 and ZrO2 subjected to thermal annealing at 400°C for 2h and 1000°C during 24h in air. The characteristic glow curves of beta particle irradiated samples exhibit an intense TL emission located around 150°C. From the shape of the TL curve, a 0.4 form factor was determined, suggesting that first order kinetics processes are involved. The afterglow decay curves were recorded after exposure to beta particle irradiation in the dose range from 0.5 up to 2kGy. The AG integrated in the time interval from 510 to 600s after radiation exposure shows a linear dependence as a function of the irradiation dose from 0.5 up to 256Gy. A method is proposed to compute the lower detection limit and the AG sensitivity and applied to the studied phosphors. Structural and morphological characterization were carried out by X-ray diffraction and Scanning Electron Microscopy, respectively. From the results presented, it is concluded that the AG response of the synthesized Li2ZrO3 presents features suitable to develop radiation detectors and dosimeters.
RESUMO
Physico-chemical and nutritional composition from four different nopalitos (young cladodes from cacti): Blanco sin Espinas, Blanco con Espinas, Verde Valtierrilla (cultivated materials) and a wild material from the central region of México were studied at different sizes of harvesting. The first three are commercial crops. None of the tested materials exhibited superior characteristics in all of the evaluated parameters in relation to each one of them. In various cases properties of the wild crop were comparable, if not superior, to commercial ones. Some important changes were observed in total soluble solids, water content, texture, acidity and pH as affected by size of cladode and specific crop. Most cladode samples appear to be a good source of beta-carotene and lutein. The presence of these compounds is important for human nutraceutical purposes.
