28078
Radiosynthesis and evaluation of [ ( 11 ) C ] EMPA as a potential PET tracer for orexin 2 receptors .
 [ ( 11 ) C ] EMPA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 [ ( 11 ) C ] EMPA