1. National University of Sciences and Technology (NUST) Islamabad Pakistan
2. Department of Mathematics Bangladesh University of Engineering and Technology Dhaka 1000 Bangladesh
3. Department of Physics Abdul Wali Khan University Mardan 23200 Pakistan
4. Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Saudi Arabia
5. Section of Mathematics International Telematic University Uninettuno Corso Vittorio Emanuele II, 39 00186 Roma Italy