20182
The presence of ammonium groups induces a weak activation of the complement whatever the size and the concentration of particles , whereas hydroxyethylenebisphosphonate ( HEBP ) - coated particles are poor complement activators only at the lowest concentration .
 Chemical: ammonium; Chemical: hydroxyethylenebisphosphonate; Chemical: HEBP
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: ammonium; Chemical: hydroxyethylenebisphosphonate; Chemical: HEBP