The 1,3-dipolar cycloaddition reactions of nitrilimine with thiazolo[3,2-a]pyrimidine derivatives was investigated. Bis-cycloadducts were obtained through a domino 1,3-dipolar cycloaddition/ring-opening/ring-opening/ ...
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The 1,3-dipolar cycloaddition reactions of nitrilimine with thiazolo[3,2-a]pyrimidine derivatives was investigated. Bis-cycloadducts were obtained through a domino 1,3-dipolar cycloaddition/ring-opening/ring-opening/ 1,3-dipolar cycloaddition processes. The structures of the products were characterized thoroughly by NMR, IR, MS, elemental analysis together with X-ray crystallographic analysis.
The ground- and excited-state intramolecular proton transfer processes of 2-(2-R (R=OH, NH2, SH) phenyl (or pyridyl)) benzoxazoles (or benzothiazoles) are investigated by the DFT methods. The calculated result...
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The ground- and excited-state intramolecular proton transfer processes of 2-(2-R (R=OH, NH2, SH) phenyl (or pyridyl)) benzoxazoles (or benzothiazoles) are investigated by the DFT methods. The calculated results indicate that in the ground state there is a high correlation (R=0.9950) between the proton transfer barrier and the intramolecular hydrogen bonds (IMHB) strength. The increase of the strength of IMHB in the proton transfer processes leads to a larger barrier contributions. Intramolecular proton transfer process pathway is along with the minimal difference of change value in the IMHB angle. In the excited-state, there is a similar relationship between the IMHB and the bartier.
Titanium-supported nanoporous palladium catalyst (Pd/Ti) was prepared by a hydrothermal method using PdC12 as a precursor, ethylenediamine tetraacetic acid (EDTA) as a ligand, and formaldehyde as a reduction agent...
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Titanium-supported nanoporous palladium catalyst (Pd/Ti) was prepared by a hydrothermal method using PdC12 as a precursor, ethylenediamine tetraacetic acid (EDTA) as a ligand, and formaldehyde as a reduction agent. Complex Pd-EDTA^2- is favorable for the formation of Pd particles with nanoscale sizes. The electroactivity of the Pd/Ti catalyst towards the electroreduction of hydrogen peroxide in 1 mol/L NaOH solution was evaluated by voltammetric techniques. Both linear scan voltammetric and chronoamperometric data present significantly large steady-state reduction current density of the hydrogen peroxide electroreduction on the prepared Pd/Ti catalyst. The results show that the prepared Pd/Ti catalyst is an effective electrocatalyst for the electroreduction of hydrogen peroxide in alkaline media.
This paper considers the Legendre Galerkin spectral approximation for the unconstralnea optimal control problems. The authors derive a posteriori error estimate for the spectral approximation scheme of optimal control...
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This paper considers the Legendre Galerkin spectral approximation for the unconstralnea optimal control problems. The authors derive a posteriori error estimate for the spectral approximation scheme of optimal control problem. By choosing the appropriate basis functions, the stiff matrix of the discretization equations is sparse. And the authors use the Fast Legendre Transform to improve the efficiency of this method. Two numerical experiments demonstrating our theoretical results are presented.
In this paper,we propose several solar cell designs based on *** numerical simulations of various designs with different materials are carried *** tests show that metamaterial solar cells are quite efficient,and over ...
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In this paper,we propose several solar cell designs based on *** numerical simulations of various designs with different materials are carried *** tests show that metamaterial solar cells are quite efficient,and over 80%and 90%absorption rates can be attained for solar spectrum and visible rays,respectively.
We present a novel adaptive finite element method(AFEM)for elliptic equations which is based upon the Centroidal Voronoi Tessellation(CVT)and superconvergent gradient *** constructions of CVT and its dual Centroidal V...
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We present a novel adaptive finite element method(AFEM)for elliptic equations which is based upon the Centroidal Voronoi Tessellation(CVT)and superconvergent gradient *** constructions of CVT and its dual Centroidal Voronoi Delaunay Triangulation(CVDT)are facilitated by a localized Lloyd iteration to produce almost equilateral two dimensional *** with finite element solutions on such high quality triangulations,superconvergent recovery methods become particularly effective so that asymptotically exact a posteriori error estimations can be *** a seamless integration of these techniques,a convergent adaptive procedure is *** demonstrated by the numerical examples,the new AFEM is capable of solving a variety of model problems and has great potential in practical applications.
Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, aceto...
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Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter o-~c and polar substituent constant crp. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (ET(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.
作者:
Bin LiuXiaofang LiKey Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education
Hunan Province College Key Laboratory of QSAR/QSPR School of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan Hunan 411201China Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education Hunan Province College Key Laboratory of QSAR/QSPR School of Chemistry and Chemical Engineering Hunan University of Science
This paper focuses on the stability analysis for uncertain Takagi–Sugeno (T–S) fuzzy systems with interval time-varying delay. The uncertainties of system parameter matrices are assumed to be time-varying and norm-b...
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This paper focuses on the stability analysis for uncertain Takagi–Sugeno (T–S) fuzzy systems with interval time-varying delay. The uncertainties of system parameter matrices are assumed to be time-varying and norm-bounded. Some new Lyapunov–Krasovskii functionals (LKFs) are constructed by nonuniformly dividing the whole delay interval into multiple segments and choosing different Lyapunov functionals to different segments in the LKFs. By employing these LKFs, some new delay-derivative-dependent stability criteria are established for the nominal and uncertain T–S fuzzy systems in a convex way. These stability criteria are derived that depend on both the upper and lower bounds of the time derivative of the delay. By employing the new delay partitioning approach, the obtained stability criteria are stated in terms of linear matrix inequality (LMI). They are equivalent or less conservative while involving less decision variables than the existing results. Finally, numerical examples are given to illustrate the effectiveness and reduced conservatism of the proposed results.
A simple A green protocol for synthesis of high quality, water-soluble and biocompatible Cd S QDs have been developed in aqueous solution with amylum as stabilizing agentThe QDs were characterized by AMF and spectral ...
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A simple A green protocol for synthesis of high quality, water-soluble and biocompatible Cd S QDs have been developed in aqueous solution with amylum as stabilizing agentThe QDs were characterized by AMF and spectral methodsA fluorescence quenching method was developed for determination of iron(ΙΙΙ) with water soluble Cd S quantum dots(QDs) as fluorescence probeIn p H 8.5 boric acid–borax buffer solution, the QDs show a high selective to ferric ionThe common cations, such as Ca2+, Mg2+, Zn2+, Fe2+ et al, have no effect on interference but copper ionThe fluorescence intensity of the QDs decreased linearly with the iron(QDs) concentration in the range of 200 μM to 60 n M with a detection limit of 20 n MIt has been applied to determinate of iron in Angelica, Astragalus, Shouwu, ligusticum wallichii and radix rehmanniae recen.
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