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In May 2007 , researchers from two Japanese universities , Tohoku University in Sendai and Osaka University , reported an ambipolar light-emitting transistor made of a single tetracene crystal .
 Tohoku University, Sendai, Osaka University
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Tohoku University, Sendai, Osaka University