1. Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-805, South Korea; Southwestern Ohio Council for Higher Education, Miami Valley Research Park, Dayton, Ohio 45420-4015; and Nanostructured & Biological Materials Branch, Materials & Manufacturing Directorate, Air Force Research Laboratory, AFRL/RXBN, Wright-Patterson Air Force Base, Dayton, Ohio 45433-7750