Institution: | a Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, P.O. Box 12, 2300 Annaba, Algeria b Department of Mathematics, Qaid-i-Azam University, Islamabad-44000, Pakistan c Department of Physics, King Saud University, P.O. Box 2455, Riyadh-11451, Saudi Arabia d Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA |