About: http://webisa.webdatacommons.org/5939348

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	A negative pressure means a pressure less than atmospheric pressure, i.e. less than 1 atm.
http://www.w3.org/ns/prov#wasQuotedFrom	freepatentsonline.com