1209
The maximum activity of dextranase was observed when the sample was treated with ultrasound at 25 kHz , 40 W for 15 min , under which the enzyme activity increased by 13 . 43 % compared the routine thermal incubation at 50 degrees C .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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