21307
The isolation of semiconducting carbon nanotubes ( CNTs ) to ultrahigh ( ppb ) purity is a prerequisite for their integration into high - performance electronic devices .
 Chemical: carbon
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: carbon 
Answer:
 Chemical: carbon