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It was found that uniform ZnO nanorods with diameter around 50 nm were formed after 15 min of ultrasonication while flowerlike ZnO - NS was formed after 30 min .
 Chemical: ZnO; Chemical: ZnO
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: ZnO; Chemical: ZnO