1. Department of Mathematics
and Natural Sciences, Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger, Norway
2. Department
of Chemistry and Polymer Science, Stellenbosch University, Private Bag
X1, Matieland 7602, South Africa
3. Center for Energy Resources Engineering, Department of
Chemical and Biochemical Engineering, Technical University of Denmark, Søltoft Plads, Building 229, DK-2800 Kgs., Lyngby, Denmark