where W0 and WF are the initial weight and the final weight of the cocoon pieces, respectively. The extraction yield was calculated using the following equation. The surface of the cocoon pieces was observed using a scanning electron microscope (SEM) (JSM-5410LV, JEOL, Japan). The filtered AmS solutions were dialyzed against distilled water in a dialysis tube (Spectra, USA, MWCO 6000-8000) for 3 days to remove the chemicals. Finally, the AmS powders were obtained by freezedrying.