Photoluminescence of Di-ureasil Hybrids Doped with Ag Silica Coated Nanoparticles “Abstracts of the Materiais 2005 /Materials´2005-XII Portuguese Materials Society Meeting and III Materials Symposium SPM” – Universidade de Aveiro, 20-23 de Março de 2005, Aveiro, Portugal, pp.136-137.