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The effects of various operating parameters were investigated , including ultrasonic frequency , power density , initial DMP concentration , solution pH and the presence of hydrogen peroxide .
 Chemical: DMP; Chemical: hydrogen peroxide
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: DMP; Chemical: hydrogen peroxide