The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fl...The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.展开更多
A new numerical approach is presented, which is used to simulate the dynamic process of metal transfer. The process of metal transfer in gas metal arc welding is simulated based on FLUENT. A two-dimensional axisymmetr...A new numerical approach is presented, which is used to simulate the dynamic process of metal transfer. The process of metal transfer in gas metal arc welding is simulated based on FLUENT. A two-dimensional axisymmetric numerical model is developed using volume of fluid method and the distributions of physical quantities including pressure, current density, electric potential in the droplet are investigated. For improving the veracity of the simulated results and decreasing the effect of the uncertain surface tension coefficient on the simulated results, the relationship between the welding current and surface tension coefficient is modified by analysis of regression. Meanwhile for testing the accuracy of simulated results, the welding experiments are performed and the high-speed photography system is used to record the real process of metal transfer. The results show that the simulated results are in reasonably good agreement with the experimental ones.展开更多
文摘The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.
基金financially supported by the National Natural Science Foundation of China (No. 51175374)the Natural Science Foundation of Tianjin (No. 11JCY-BJC06100)the State Key Lab of Advanced Welding and Joining, Harbin Institute of Technology (No. AWPT-M12-08)
文摘A new numerical approach is presented, which is used to simulate the dynamic process of metal transfer. The process of metal transfer in gas metal arc welding is simulated based on FLUENT. A two-dimensional axisymmetric numerical model is developed using volume of fluid method and the distributions of physical quantities including pressure, current density, electric potential in the droplet are investigated. For improving the veracity of the simulated results and decreasing the effect of the uncertain surface tension coefficient on the simulated results, the relationship between the welding current and surface tension coefficient is modified by analysis of regression. Meanwhile for testing the accuracy of simulated results, the welding experiments are performed and the high-speed photography system is used to record the real process of metal transfer. The results show that the simulated results are in reasonably good agreement with the experimental ones.
