1. Department of Materials Engineering; Ben Gurion University of the Negev; Beer-Sheva 84105 Israel
2. Department of Electrical and Computer Engineering; UC San Diego; La Jolla CA 92093-0407 USA
3. Institute of Chemistry and The Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
4. Department of Molecular Microbiology and Biotechnology; Department of Materials Science and Engineering; Tel Aviv University; Tel Aviv 69978 Israel