1. Photoenergy Center, Faculty of Science, Ain Shams University, Abbassia, Cairo 11566, Egypt
2. Dessert Environment Research Institute, Sadat City, Menoufia University, Egypt
3. Polymer Chemistry Department, National Center for Radiation Research and Technology, 3 Ahmed El-Zohor St., El-Zohor Distr., Nasr City, P.O. box 29, Cairo, Egypt