http://comum.rcaap.pt/handle/123456789/860 2013-05-22T21:10:37Z 2013-05-22T21:10:37Z Pardal, Ana Cristina Ramos, S.S. Santos, P. F. Reis, L. V. Almeida, P. http://comum.rcaap.pt/handle/123456789/1295 2011-09-27T10:46:27Z 2002-01-01T00:00:00Z

Title: Synthesis and spectroscopic characterisation of n-alkyl quaternary ammonium salts typical precursors of cyanines Authors: Pardal, Ana Cristina; Ramos, S.S.; Santos, P. F.; Reis, L. V.; Almeida, P. Abstract: The synthesis and spectroscopic characterisation of some representative N-alkylsubstituted quaternary ammonium salts derived from benzothiazole, benzoxazole, benzoselenazole, indole and quinoline are described. These heterocyclic salts, bearing an activated methyl group in the 2-position in relation to the nitrogen atom and N-methyl, -pentyl, -hexyl and -decyl chains, are typical precursors of cyanine dyes.

2002-01-01T00:00:00Z Palma, Patrícia Barbosa, I.R. http://comum.rcaap.pt/handle/123456789/1279 2011-09-23T01:14:10Z 2011-01-01T00:00:00Z

Title: Embryo-toxic effects of atrazine environmental concentrations on the crustacean Daphnia magna Authors: Palma, Patrícia; Barbosa, I.R. Abstract: Atrazine is one of the most used pesticides all over the world and it is frequently detected in surface water. The aim of this study was to evaluate the effects promoted by environmental concentrations of atrazine on the embryo development of Daphnia magna. All the concentrations induced a percentage of embryo abnormalities higher than 78%. The profile of embryo abnormalities included effects in both stages of embryo development (gastrulation and organogenesis). At the lowest concentration (1 µg L-1) we noted the appearance of 20% of arrested eggs. This effect increased with the concentrations, which indicate the increment of the effects severity. Therefore, the maximum allowable concentration proposed for atrazine by the environmental quality standards (2 µg L-1) induces high toxic effects to the exposure embryos.

2011-01-01T00:00:00Z