1. Pan African University Institute of Basic Sciences and Technology, PAUSTI, Nairobi, Kenya
2. Jomo Kenyatta University of Agriculture and Technology, JKUAT, Nairobi, Kenya
3. Laboratory of Energy, Materials, Modeling, and Method of the University of Douala, Douala, Cameroon
4. National higher polytechnic school of Douala, University of Douala, Douala, Cameroon