1. São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560-970, São Carlos, SP, Brazil
2. Department of Physics, Federal University of Pelotas, P.O. Box 354, 96010-900, Pelotas, RS, Brazil
3. Department of Biological Sciences, Federal University of Piauí, P.O. Box 64900-000, 64900-000 Bom Jesus, PI, Brazil