[1] Institute of Materials Science, N.C.S.R. Demokritos, GR-15310 Agia Paraskevi Athens, Greece
[2] Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina, Greece
[3] Center of Excellence for Nanostructured Materials (CENMAT), Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy