14781
After the last self - administration session , rats were moved to polycarbonate cages for a 10 - day abstinence period where they either had access to a locked or unlocked running wheel for 2 h / day .
 polycarbonate
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 polycarbonate