Affiliation: | a Applied Mathematics Research Center, Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA b Department of Chemistry, Ferdowsi University of Mashhad, Mashhad 91775-1436, Iran c Applied Mathematics Research Center, Center for Research and Education in Optical Sciences and Applications, Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA |