1. Department of Chemistry and Exact Sciences, Universidad Técnica Particular de Loja, P.O. Box 11 01 608, Loja, Ecuador
2. School of Architecture and Cities, University of Westminster, London, UK
3. Departamento de Ingeniería Civil, Universidad de Burgos, Avda. Cantabria s/n, Burgos 09006, Spain
4. Department of Applied Mathematics & Comp Science, Universidad de Cantabria, Santander, Spain