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A regional distribution of Fe ( 3 ) O ( 4 ) - NPs was observed in rat brains after the particles were intranasally instilled for seven days .
 Chemical: Fe ( 3 ) O ( 4 )
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: Fe ( 3 ) O ( 4 )