( ( Because ( of ( ( ( its ( low ( atomic number ) ) ) and ) ( ( ( very low ) absorption ) ( for X-rays ) ) ) ) ) ( , ( ( ( ( the oldest ) and ) ( ( still one ) ( of ( ( the ( ( most important ) applications ) ) ( of beryllium ) ) ) ) ) ( ( is ( in ( ( radiation windows ) ( for ( X-ray tubes ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Because) (PP (IN of) (NP (NP (PRP$ its) (JJ low) (JJ atomic) (NN number)) (CC and) (NP (NP (ADJP (RB very) (JJ low)) (NN absorption)) (PP (IN for) (NP (NNS X-rays))))))) (, ,) (NP (NP (DT the) (JJS oldest)) (CC and) (NP (NP (RB still) (CD one)) (PP (IN of) (NP (NP (DT the) (ADJP (RBS most) (JJ important)) (NNS applications)) (PP (IN of) (NP (NN beryllium))))))) (VP (VBZ is) (PP (IN in) (NP (NP (NN radiation) (NNS windows)) (PP (IN for) (NP (NN X-ray) (NNS tubes)))))) (. .)))
Because of its low atomic number and very low absorption for X-rays, the oldest and still one of the most important applications of beryllium is in radiation windows for X-ray tubes.
(ROOT (S (NP (NP (DT The) (JJ low) (JJ atomic) (NN number)) (PP (IN of) (NP (NN beryllium)))) (VP (VBZ allows) (S (NP (PRP it)) (VP (TO to) (VP (VB absorb) (NP (NNPS x-rays)))))) (. .)))