PMC:7796291 / 9166-9501 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T80","span":{"begin":0,"end":4},"obj":"Sentence"},{"id":"T81","span":{"begin":5,"end":36},"obj":"Sentence"},{"id":"T82","span":{"begin":37,"end":199},"obj":"Sentence"},{"id":"T83","span":{"begin":200,"end":335},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"2.3. Electrostatic Force Measurement\nThe 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. A charge-monitoring probe was placed 4 cm above the web surface, and the surface potential was measured by line-scanning over the area."}