( ( ( ( ( Low-temperature ( light emission ) ) , ) ( also ( known ( as luminescence ) ) ) ) , ) ( ( ( has always ) ( ( surrounded us ) ( in ( the ( natural world ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Low-temperature) (JJ light) (NN emission)) (, ,) (VP (ADVP (RB also)) (VBN known) (PP (IN as) (NP (NN luminescence)))) (, ,)) (VP (VBZ has) (ADVP (RB always)) (VP (VBN surrounded) (NP (PRP us)) (PP (IN in) (NP (DT the) (JJ natural) (NN world))))) (. .)))
Low-temperature light emission, also known as luminescence, has always surrounded us in the natural world.
(ROOT (S (NP (NP (NNP Producing) (NN light)) (PP (IN without) (NP (DT a) (JJ high) (NN temperature)))) (VP (VBZ is) (VP (VBN called) (S (ADJP (JJ luminescence))))) (. .)))