A relation which is between a process, a continuant and a time whenever the continuant is a participant in the process and is at the same time directly causally responsible for its occurrence.

Emulsification has_agent Emulsifier

Smith B, Ceusters W, Klagges B, Kohler J, Kumar A, Lomax J, Mungall C, Neuhaus F, Rector AL, Rosse C: Relations in biomedical ontologies. Genome Biol 2005, 6: R46.