Sentence:  Some 80 reaction tubes from 13 manifold fillings were illuminated in the temperature range from 40 to 85 ` in a further <WSD>endeavor</WSD> to determine 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:  a purposeful or industrious undertaking (especially one that requires effort or boldness)