2461
We showed that cross - flow filtration is efficient for concentrating the droplets and reducing the concentration of free surfactant from 10wt . % to 1wt . % , without any changes in the nano - emulsion droplet morphologies or surface properties .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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