PMC:7796291 / 9203-9365 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T82","span":{"begin":0,"end":162},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"The surface potential of filter media was measured using an electrostatic voltmeter (Model 542A, Trek, Lockport, NY, USA), by holding the filter media in the air."}