A selective and validated stability-indicating LC method was developed for the kinetic study of the degradation of PAC-1, which was carried out in aqueous solutions at 37, 60, 80 and 100 °C with pH 1.5–9.0. Separation was performed on a Kromasil C18 column with acetonitrile–water–fomic acid (30:70:0.1, v/v/v) as mobile phase with a flow rate of 1.0 mL min−1 at 281 nm. The degradation rate obtained indicated a first-order reaction law and the activation energy (Ea) was calculated. The results showed that temperature and pH values were significant factors affecting the degradation of PAC-1. An unknown degradation product in alkaline condition was isolated using a reverse-phase semi-preparative LC system. The structure of the degradation product is identified as 2-hydroxy-3-(2-propenyl)-[[2-hydroxy-3-(2-propenyl)phenyl]methylene]hydrazone utilizing the 1H NMR, 13C NMR, IR and Q-TOF-MS techniques.
This communication reports on a novel amperometric hydrazine sensor of CuO nanoarray based on a Cu substrate. Copper oxide nanoarray was directly grown on Cu substrates using a one-step facile hydrothermal method and was characterized using scanning electron microscopy and X-ray powder diffraction. The electrochemical study has shown that the CuO nanoarray exhibits higher catalytic effect on the hydrazine than the normal CuO nanoparticles. This may be attributed to the special structure of the nanomaterials esp. the substrate of the electric Cu. And the amperometric response showed that the CuO nanoarray modified glassy carbon electrode has a low detection and a high sensitivity for hydrazine. 相似文献
In this paper, we consider a generalized system in the framework of the formulation proposed by Blum and Oettli. The concepts
of feasibility and strict feasibility are introduced for a generalized system and a feasibility-solvability theorem is obtained.
This work was supported by the Foundation for Young Teacher in Sichuan University (07069), the National Natural Science Foundation
of China (10826064, 10671135) and the Specialized Research Fund for the Doctoral Program of Higher Education (20060610005).
The authors thank Professor L.D. Muu (Hanoi) and the referee for valuable comments and suggestions which lead to improvements
of this paper. 相似文献
The dissociation of [CuII(L)His]•2+ complexes [L=diethylenetriamine (dien) or 1,4,7-triazacyclononane (9-aneN3)] bears a strong resemblance to the previously reported behavior of [CuII(L)GGH]•2+ complexes. We have used low-energy collision-induced dissociation experiments and density functional theory (DFT) calculations
at the B3LYP/6-31+G(d) level to study the macrocyclic effect of the auxiliary ligands on the formation of His•+ from prototypical [CuII(L)His]•2+ systems. DFT revealed that the relative energy barriers of the same electron-transfer (ET) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ are very similar, with the ET reactions of [CuII(9-aneN3)His]•2+ leading to the generation of two distinct His•+ species; in contrast, the proton transfer (PT) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ differ considerably. The PT reactions of [CuII(9-aneN3)His]•2+ are associated with substantially higher barriers (>13 kcal/mol) than those of [CuII(dien)His]•2+. Thus, the sterically encumbered auxiliary 9-aneN3 ligand facilitates ET reactions while moderating PT reactions, allowing the formation of hitherto nonobservable histidine
radical cations. 相似文献
The reaction mechanism of phenylamine reacting with 1,4-butanediol to give N- phenylpyrrolidine was investigated with traditional transition state theory. Based on the experimental results, two reaction channels were discussed. The geometries of their reactants, products, intermediates and transition states were optimized. The possible transition State and activation energy were determined by vibrational analysis and IRC verification. And finally, the main reaction channel was given. 相似文献
As an important intermediate to study cyclin-dependent kinase(CDK)inhibitors,2-aryl-8-(piperidin-4-yl)-5,7-dimethoxy-4H- chromen-4-one derivatives were prepared usingβ-diketone route with low yield.In our study,chalcone route has been investigated and the result suggested that the benzaldehydes substituted with electron-donating group give much better yield thanβ-diketone route.This new method will be an efficient way to start further research on new anticancer flavonoids. 相似文献
Here we generalize the “BBH”-asymptotic analysis to a simplified mathematical model for the planar ferromagnets and antiferromagnets.
To develop such a static theory is a necessary step for a rigorous mathematical justification of dynamical laws for the magnetic
vortices formally derived in [1] and [2].
Received March 15, 2001, Accepted May 16, 2001 相似文献
The physiological functions of the two ions, Ca2+ and H+, in controlling mechanical properties of plant cell wall are reviewed. The interactions of these ions with major cell wall
polysaccharides during cell growth and development are described. Experimental results for Ca2+/H+-induced molecular associations of some polysaccharides in solutions are also given. This article aims to bridge the understandings
of molecular associations in solutions (in vitro) with those occurring in cell wall matrix of high order structure (in vivo). 相似文献