Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiom...Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.展开更多
The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corr...The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corrosion behavior of these three samples was examined in the very aggressive solution of 50% H2SO4(mass fraction) using electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization measurements. The results show that magnesium improves in some extent the corrosion resistance of pure Zn in 50% H2SO4(mass fraction) confirmed by EIS test. Results of polarization measurment also demonstrate that small amount of Mg significantly improves the passivation of Zn in the test solution. Results of surface morphology of the samples and EDS analysis reveal that Mg reduced the corrosion attacks to pure Zn.展开更多
基金Project(20976041) supported by the National Natural Science Foundation of China
文摘Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.
文摘The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corrosion behavior of these three samples was examined in the very aggressive solution of 50% H2SO4(mass fraction) using electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization measurements. The results show that magnesium improves in some extent the corrosion resistance of pure Zn in 50% H2SO4(mass fraction) confirmed by EIS test. Results of polarization measurment also demonstrate that small amount of Mg significantly improves the passivation of Zn in the test solution. Results of surface morphology of the samples and EDS analysis reveal that Mg reduced the corrosion attacks to pure Zn.
