Síntese e estudo de ortossilicatos de zinco luminescentes com aplicação da técnica sol-gel

Usually, the concepts of the Sol-Gel technique are not applied in experimental chemistry courses. This work presents a feasible experiment for chemistry instruction, which involves the synthesis of luminescent materials - Zn2SiO4, with and without Mn2+ as a dopant - by the Sol-Gel technique. The obtained materials were analyzed by scanning electron microscopy, X-Ray diffraction, IR spectroscopy and luminescence measures by UV-vis spectroscopy. The results allow the students to confirm the luminescent properties of the zinc orthosilicate luminophores as well as the structural features expected from literature data.

Féculas fermentadas na fabricação de biscoitos: estudo de fontes alternativas

The fermented cassava starch has been used as raw material for many products of the Brazilian culinary mainly in the biscuit manufacturing. Starch of arrowroot, english potato, baroa-potato and cassava were extracted and fermented in order to investigate other fermented starch sources for manufacturing biscuits. The fermented starch showed characteristics similar to those of commercial fermented cassava starch. The biscuits manufactured from the fermented starch of english potato didn?t expand and was very hard and the biscuits manufactured from the fermented starch of arrowroot and of baroa-potato were approved by the consumers and can be used in the biscuit manufacturing the same way as the fermented cassava starch.