$npo = {
  "Localized Surface Plasmon Resonance (LSPR) index" => "http://bioportal.bioontology.org/ontologies/OBI?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FOBI_0001136",
  "ZETA POTENTIAL" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.bioontology.org%2Fontology%2Fnpo%23NPO_1302",
  "Total protein (BCA assay)" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FOAE_0001659",
  "Core size" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.enanomapper.org%2Fonto%2FENM_8000039",
  "Z-Average Hydrodynamic Diameter" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.bioontology.org%2Fontology%2Fnpo%23NPO_1915",
  "Volume Mean Hydrodynamic Diameter" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.bioontology.org%2Fontology%2Fnpo%23NPO_1915",
  "Intensity Mean Hydrodynamic Diameter" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.bioontology.org%2Fontology%2Fnpo%23NPO_1915",
  "Autot (ICP-AES)" => "http://bioportal.bioontology.org/ontologies/ERO?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FERO_0001675",
  "Polydispersity index" => "http://bioportal.bioontology.org/ontologies/ENM?p=classes&conceptid=http%3A%2F%2Fpurl.bioontology.org%2Fontology%2Fnpo%23NPO_1155"
}