13C CP/MAS NMR spectra recorded from a) Fortisan, b) Fortisan after ammonia treatment for 1h at 140°C, c) Fortisan after ammonia treatment for 1h at 160°C, d) mercerized ramie, e) mercerized ramie after ammonia treatment for 1h at 180°C, f) cellulose IIII produced by ammonia treatment of cellulose extracted from Cladophora,28,29 a′-e′) same as a-e) with resolution enhancement.