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In 1946 , he returned to Imperial College as Professor and Head of the Department of Mechanical Engineering .
 organization: Imperial; organization: Mechanical Engineering
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Imperial, Mechanical Engineering 
Answer:
 organization: Imperial; organization: Mechanical Engineering