摘要：
Weak organic acids including tartaric and citric acids were applied to a typical paddy soil in southern China to test their effects on rice in the field for three years. Their effects were also compared with top dressings of the two acids, basal application of diammonium acid phosphate, calcium carbonate, and the control. The results showed that rice grain yield of the citric acid treatment was significantly higher than that of the control and the same difference was also observed for the filled spikelets per panicle. There were no significant difference among all the treatments and the control on the accumulation of above ground dry matter. However the root dry matter, length, peroxidase activity, and white root number of citric acid treatment were significantly higher than that of the control, while no significant differences among other treatments were observed. Basal application of citric acid played a positive role on this soil.
期刊：
International Journal of Mass Spectrometry,2009年286(2-3):112-121 ISSN：1387-3806
通讯作者：
Liang, Yi-Zeng
作者机构：
[Ouyang, Yong-Zhong; Xu, Xiaona; Zhang, Liangxiao; Luo, Xiao; Liang, Yi-Zeng; Tang, Zhonghai] Cent S Univ, Coll Chem & Chem Engn, Res Ctr Modernizat Chinese Med, Changsha 410083, Peoples R China.;[Li, Shuhua] Nanjing Univ, Key Lab Mesoscop Chem MOE, Dept Chem, Inst Theoret & Computat Chem, Nanjing 210093, Peoples R China.;[Tang, Zhonghai] Hunan Agr Univ, Coll Biosci & Biotechnol, Changsha 410128, Hunan, Peoples R China.;[Xu, Xiaona] Univ S China, Coll Chem & Chem Engn, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Liang, Yi-Zeng] C;Cent S Univ, Coll Chem & Chem Engn, Res Ctr Modernizat Chinese Med, Changsha 410083, Peoples R China.
关键词：
Characteristic fragmentation mechanism;Initial ionization site;Radical site;Atomic spin density;Ionization energy
摘要：
The characteristic fragmentation mechanisms of the derivatives of tryptophan and tryptamine are investigated by the density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The main primary alpha-cleavage fragmentation has been predicted through determining the initial ionization site by calculated spin density of molecular radical cation and the variation of molecular structures from neutral to cationic form. The results show that the more intensive base peak produced by main primary alpha-cleavage fragmentation predicted in the present agrees well with those of experimental mass spectra, which is useful for characterizing the fragmentation mechanisms of such indole alkaloids. More importantly, the novel method for determining the most likely initial ionization site proposed in this study is prior to that based on the ionization energy (IE). It will play an important role in unraveling the mechanisms of radical-driven fragmentation not only for small molecules, but also for gas-phase peptides occurring in electron capture dissociation (ECD), electron transfer dissociation (ETD), or low-energy CID of peptide radical cations. However, this study is inappropriate for negative systems. (C) 2009 Elsevier B.V. All rights reserved.
摘要：
Xiao, H., JunFang, Lu, X., Liu, Z., Chen, X., Liu, J., Su, J., Yi, J. and Sun, Z. 2009. Protective effect of soluble fiber from Undaria pinnatifida on vascular endothelium in hypercholesterolemic rabbits. Can. J. Anim. Sci. 89: 361-367. Dietary fiber could improve endothelial function and abnormal production of nitric oxide (NO) and elevated endothelin-1 (ET-1) concentration induce endothelial dysfunction. In the present study, we tested the effect of soluble fiber extracted from Undaria pinnatifida (UP) on endothelial function and NO and ET-1 production in hypercholesterolemic rabbits. After treatment with UP soluble fiber (5 or 10%) for 8 wk, endothelium-dependent vasorelaxation in isolated aortic rings, the concentrations of NO and ET-1 and malondialdehyde (MDA), and the expression of endothelial NO synthase (eNOS) gene were measured. The UP soluble fiber (5 or 10%) treatment significantly attenuated the impairment of endotheliumdependent vasorelaxation concomitantly with increase of plasma NO concentration and expression of aortic endothelial nitric oxide synthase (eNOS), reduction of plasma MDA level and ET-1 concentration and aortic ET-1 concentration. The present study indicates that the protective effects of UP soluble fiber on endothelium-mediated vasorelaxation may be related to an improved NO production and a reduced ET-1 concentration in hypercholesterolemic rabbits.
