* Corresponding authors

^a School of Engineering, University of Cyprus, 75 Kallipoleos Avenue, P.O. Box 20537, 1678 Nicosia, Cyprus
E-mail: ioannis@ucy.ac.cy
Fax: +357 22892295
Tel: +357 22892257

^b Centre for Materials Science & Engineering and School of Engineering & Electronics, The University of Edinburgh, The King's Buildings, Edinburgh, UK

^c School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, P.O. Box 88, Manchester, UK

^d Department of Crystallography, Birkbeck College, University of London, Malet Street, London, UK