3875
A periodically aligned array of graphene nanorings ( GRNRs ) with a sub - 15 nm linewidth at a pitch of 450 nm is fabricated with a large area , 9 cm ( 2 ) , through conventional nanoimprint lithography coupled with sophisticated metal deposition and plasma - etching processes .
 Chemical: graphene
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: graphene