Assertion: lignin's group | /r/HasProperty | ; sakakibara
Facets:
Source sentences:
text: A puzzling aspect of the effects just described is the fact that the best-known molecular models of lignin structure show few if any groups that would take on a negative charge at pH values below about 9 (Pearl 1967; Sakakibara 1980; Glasser and Sarkanen 1989).