1. Institute of Ground Water Studies, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9301, South Africa; Department of Basic Sciences and Related Studies, Mehran University of Engineering and Technology, Jamshoro 76020, Pakistan
2. Institute of Ground Water Studies, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9301, South Africa; Department of Medical Research, China Medical University Hospital, China, Medical University, Taichung 110122, Taiwan