1. Department of Energy Engineering; Hanyang University; Seoul 133-791 South Korea
2. Qatar Environment and Energy Research Institute; HBKU; Qatar Foundation; P.O. Box 5825 Doha Qatar
3. College of Science and Engineering; HBKU; Qatar Foundation; P.O. Box 5825 Doha Qatar
4. Materials Science and Engineering Program and Texas Materials Institute; The University of Texas at Austin; Austin TX 78712 USA