26095
In an alkane - water system containing submicrometer silica particles at high pH , double emulsion inversion from oil - in - water ( o / w ) to water - in - oil ( w / o ) to oil - in - water can be effected by increasing the concentration of a dichain cationic surfactant in water .
 silica
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 silica