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Gamma-induced modification on optical band gap of CR-39 SSNTD
Zaki,M. F.Effect of gamma irradiation on optical absorption of nuclear track detectors like CR-39 was studied in different absorbed doses using ultraviolet-visible (UV-VIS) spectroscopy. The existence of the peaks, their shifting and broadening as a result of gamma irradiation has been discussed. The width of the tail of localized states in the band gap (Eu) was evaluated using the Urbach edge method. Finally the indirec...
New synthetic compounds as inhibitors of mycotoxin synthesis
Abrunhosa, Luís; Zaki, M.; Areias, F.; Proença, M. Fernanda R. P.; Venâncio, ArmandoOchratoxin A (OTA) is a mycotoxin produced by some Aspergillus and Penicillium species which is often detected in beer, cereals, coffee, feeds, figs, sultanas and wine. Some fungicides have been found to be effective in preventing fungal growth, but, in other cases, an increase in the synthesis of mycotoxins was reported. Also, the pressure to use less harmful compounds to the environment stimulates the explora...
Synthesis of novel 6-enaminopurines
Carvalho, M. Alice; Zaki, M.; Proença, M. Fernanda R. P.; Booth, Brian L.; Álvares, YolandaTwo different approaches have been used for the synthesis of 6-enaminopurines 6 from 5-amino-4-cyanoformimidoyl imidazoles 1. In the first approach imidazoles 1 were reacted with ethoxymethylenemalononitrile or ethoxymethylenecyanoacetate under mild experimental conditions and this led to 9-substituted-6-(1-amino-2,2-dicyanovinyl) purines 6a-f or 9-substituted-6-(1-amino-2-cyano-2-methoxycarbonylvinyl) purines ...
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