1. Department of Civil Engineering, National Advanced School of Engineering, University of Yaoundé I, Yaoundé, Cameroon
2. Ceramic Department, Faculty of Fine Arts, Afyon Kocatepe University, Afyonkarahisar, Turkey
3. Department of Minerals Engineering, School of Chemical Engineering and Mineral Industries (EGCIM), University of Ngaound´er´e, Ngaoundere, Cameroon
4. Department of Physics, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia