29604
The O2 and / or H2O pressure acts quantitatively as an instantaneously reversible " molecular gating " force , providing orders of magnitude broader control of carrier density and light emission than conventional electric field gating .
 Chemical: O2; Chemical: H2O
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: O2; Chemical: H2O