1. A. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering Drexel University Philadelphia PA 19104 USA
2. Department of Electrical and Computer Engineering Drexel University Philadelphia PA 19104 USA
3. Department of Electrical and Computer Engineering Villanova University Villanova PA 19085 USA
4. Lockheed Martin Co. Moorestown NJ 08057 USA