Sentence:  Some 80 reaction tubes from 13 manifold fillings were illuminated in the temperature range from 40 to 85 ` in a further endeavor to <WSD>determine</WSD> the cause of the irreproducibility and to obtain information on the activation energy and the effect of light intensity . 
Meaning of the word marked with <WSD> tags:  establish after a calculation, investigation, experiment, survey, or study