1. The Department of Materials and Energy Science & Engineering, The Nelson Mandela African Institution of Science and Technology, P.O. Box 447Arusha, Tanzania
2. Department of Chemistry, Dar es Salaam University College of Education, P.O. Box 2329, 255Dar es Salaam, Tanzania
3. Biochemistry and Molecularbiology, University of Hamburg Institute of Biochemistry and Molecularbiology, Hamburg, Germany
4. Department of Basic Sciences, School of Medicine, University of Kinshasa, Kinshasa, Congo (Democratic Republic of the)
5. The Department of Water and Environmental Science and Engineering, The Nelson Mandela African Institution of Science and Technology, P.O. Box 447Arusha, Tanzania
6. Department of Pharmaceutical Chemistry, Martin-Luther University Halle-Wittenberg, Wolfgang-Langenbeck Str. 4, Halle (Saale)06120, Germany
7. Department of Informatics and Chemistry, University of Chemistry and Technology Prague, Technická 5, Prague 6, Dejvice 166 28, Czech Republic
8. Department of Chemistry, University of Buea, P. O. Box 63Buea, Cameroon