One of the advantages of using RDF in combination with ontology annotation is that the ontological tree structure can be used to group the materials using their annotation of material type. For example, MWCNTs and SWCNTs can be grouped by the parent term CNTs, or information related to all metal oxides can be queried at once. This is a useful feature that makes exploring groups of related nanomaterials possible. For example, to get all silver nanoparticles in the RDF, the following query takes the ontology term we assigned to each nanomaterial (dcterms:type ?t) and queries for the parent of this term (rdfs:subClassOf* ?parent), filtering it to be a silver particle.