no substitute for on-screen chemistry 
(ROOT (NP (NP (DT no) (NN substitute)) (PP (IN for) (NP (NML (PP (IN on) (HYPH -) (NP (NN screen)))) (NN chemistry)))))
(ROOT (NP (NP (DT ) (NN )) (PP (IN ) (NP (NML (PP (IN ) (HYPH ) (NP (NN )))) (NN )))))