1. Complex Fluids Laboratory, CNRS-Rhodia, Prospect Plains Road, Cranbury, New Jersey, 08512, Centre de Recherches d'Aubervilliers, Rhodia, 52, rue de la Haie coq, 93308 Aubervilliers, France, and Institut Charles Sadron, 6 rue Boussingault, 67000 Strasbourg, France