1. Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, IL 60607, USA.
2. Department of Mechanical Engineering, Chungbuk National University, Cheongju 361-763, South Korea.
3. Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
4. Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA.
5. Department of Civil Engineering, University of New Mexico, Albuquerque, NM 87131, USA.
6. Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
7. Conn Center for Renewable Energy Research, University of Louisville, Louisville, KY 40292, USA.