1. Dipartimento di Ingegneria, Viale delle Scienze ed.8, 90128 Palermo, Italy
2. Bio/NanoMechanics for Medical Sciences Laboratory, Viale delle Scienze ed.8, 90128 Palermo, Italy
3. Department of Civil and Environmental Engineering, Carnegie Mellon University Pittsburgh, Pittsburgh, PA 15213, USA
4. Center for Nonlinear Analysis, Carnegie Mellon University Pittsburgh, Pittsburgh, PA 15213, USA
5. Department of Materials Science and Engineering, Carnegie Mellon University Pittsburgh, Pittsburgh, PA 15213, USA
6. Department of Mechanical Engineering, University of Pittsburgh, Benedum Hall, Pittsburgh, PA, USA
7. Dipartimento Civile, ambientale e meccanica, Università degli Studi di Trento, Via Mesiano, 77 - 38123 Trento, Italy
8. Department of Mechanical Engineering, Department of Civil & Env. Engineering, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
9. The Methodist Hospital Research Institute, Department of Nanomedicine, 6565 Fannin St., MS B-490, Houston, TX 77030, USA