Sentence:  At the end of the run , the strips in the third and sixth positions in each chamber were dried , stained for 1 hr , washed and dried , while the other strips were <WSD>maintained</WSD> in a horizontal position at 1 ` C . 
Meaning of the word marked with <WSD> tags:  keep in a certain state, position, or activity; e.g., "keep clean"