The last component of the NanoLinks semantic model is the nanomaterial characteristics description (Figure ). This part is based on the NanoParticle Ontology (NPO) to represent a nanomaterial entity. According to the NPO ontology, the nanomaterial class npo:NPO 199 is equivalent to being both a chemical substance chebi:CHEBI 59999 and a nanoparticle npo:NPO 707, which is the case in Figure . Moreover, the nanomaterial entity is annotated with another class, molecular entity bao:BAO 0003043 to establish the link between the bioassay and the nanomaterial model parts. The molecular entity describes the participant or the perturbagen that is related to both the bioassay and measure groups using the predicates "has participant" (bao:BAO 0090012 ) and "has perturbagen" (bao:BAO 0000185 ), respectively.