Combined crossed molecular beam and ab initio investigation of the reaction of boron monoxide (BO; X(2)Σ(+)) with 1,3-butadiene (CH2CHCHCH2; X(1)Ag) and its deuterated counterparts.

The reactions of the boron monoxide ((11)BO; X(2)Σ(+)) radical with 1,3-butadiene (CH2CHCHCH2; X(1)Ag) and its partially deuterated counterparts, 1,3-butadiene-d2 (CH2CDCDCH2; X(1)Ag) and 1,3-butadiene-d4 (CD2CHCHCD2; X(1)Ag), were investigated under single collision conditions exploiting a crossed molecular beams machine. The experimental data were combined with the state-of-the-art ab initio electronic structure calculations and statistical RRKM calculations to investigate the underlying chemical reaction dynamics and reaction mechanisms computationally. Our investigations revealed that the reaction followed indirect scattering dynamics through the formation of (11)BOC4H6 doublet radical intermediates via the barrierless addition of the (11)BO radical to the terminal carbon atom (C1/C4) and/or the central carbon atom (C2/C3) of 1,3-butadiene.

[A case-control study on the relationship between stroke and plasma homocysteine level and the mutation of MTHFR gene].

Objective: To study the relationship of stroke and plasma homocysteine (Hcy) level and the mutation of methylenetetrahydrofolate reductase (MTHFR) gene.

Methods: Three hundred patients with stroke were included as the case group in this study while 300 subjects without stroke matched with the case group for sex and age were collected as the control group. Plasma Hcy level was measured using HPLC and MTHFR 667C-->T mutant was determined by polymerase chain reaction and restriction fragment analysis.