Optimization process using response surface analysis of extract yield and coumarin concentration of Guaco (Mikania laevigata and Mikania glomerata) obtained by supercritical carbon dioxide extraction - Oliveira, Alessandra Lopes de; Pozza, Letícia Nasser Lauandos; Kamimura, Eliana Setsuko; Vicente, Eduardo; Cabral, Fernando Antonio (International Symposium on Supercritical Fluids, 2009)