1. Department of Mathematics, University of the Aegean 1 , Karlovassi, Samos 83200, Greece
2. Department of Chemical and Biomolecular Engineering, University of Delaware 2 , Newark, Delaware 19716
3. Center for Research in Soft Matter & Polymers (CRiSP), Department of Chemical and Biomolecular Engineering, University of Delaware 3 , Newark, Delaware 19716