1. Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi-2, Niigata 9050-2181, Japan
2. Faculty of Science, Tanta University, Tanta 511111, Egypt
3. Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan