Sentence:  A significant effect discovered during the study is the existence of Prandtl numbers reaching values of more than unity in the <WSD>nitrogen</WSD> dissociation region . 
Meaning of the word marked with <WSD> tags:  a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissues