1. Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588 89694, Tehran, Iran
2. Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran, Iran
3. Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box: 11155-9466, Tehran, Iran
4. Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box: 14115-175, Tehran, Iran