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Zhu H.J.,Yunnan University | Zhu H.J.,Beijing Municipal Tobacco Company | Cheng W.X.,Yunnan University | Chen Y.L.,Yunnan University | And 3 more authors.
Asian Journal of Chemistry | Year: 2013

The gas phase Cu+-activated fragmentation of D-alanine was theoretically investigated at B3LYP and MP2 levels. The experimentally observed products can be rationalized by the mechanism as: Cu++D-alanine → η 2 (NH2, C=O) complex → Cα-COOH bond insertion → O=C-OH bond insertion → H migration from -NH2 to -OH → [CH3CHNH-(H2O)Cu(CO)]+. Dissociations of the final intermediate in different forms produce the products corresponding to loss of H2O, CO and H2O + CO, respectively. Another product channel leading to elimination of HCOOH was also identified but it is energetically less favourable than the first one. By comparing the Cu + + alanine reaction with previously studied Cu+ + phenylalanine reaction, it was concluded that different a-amino acids may share common reaction mechanisms for the same product channels. Different side chains change the reactivity but do not change the mechanisms significantly.

Liu Y.,Beijing Municipal Tobacco Company | Zhu H.,Beijing Municipal Tobacco Company | Yang L.,Beijing Municipal Tobacco Company | Zhang Y.,Beijing Municipal Tobacco Company
Tobacco Science and Technology | Year: 2013

The distribution of 5 volatile organic compounds (VOCs, including 1,3-butadiene, isoprene, acrylonitrile, benzene and toluene) between mainstream and sidestream cigarette smoke, affected by cigarette physical indexes (CPIs, including the weight, length, circumference, hardness and draw resistance of cigarette and the ventilation rates of filter and cigarette paper) was investigated with regression analysis and path analysis. The results showed that: 1) the distribution ratio of VOCs significantly correlated with CPI by multiple regression relationships. 2) The said ratio was extremely significantly affected by filter ventilation rate, while the effects of other CPIs differed depending on properties of each compound.

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