poly(ethylene glycol) with three molec- ular weights 2000, 4000, and 8000, (NH4)2SO4,K3PO4, and soluble starch were obtained from Aldrich (Milwau- kee, WI, USA).
poly(ethylene glycol) with three molec- ular weights 2000, 4000, and 8000, (NH4)2SO4,K3PO4, and soluble starch were obtained from Aldrich (Milwau- kee, WI, USA).