A simple model of chromatographic mechanical mechanism is present, and then a scrics of theoretical chromatographic equations and fundamental Formulae are derived. These theoretical equations and formulae not only res...A simple model of chromatographic mechanical mechanism is present, and then a scrics of theoretical chromatographic equations and fundamental Formulae are derived. These theoretical equations and formulae not only reserve thermodynamic characteristics in the current fundamental chromatographic formulae, but also introduce one or more kinetic parameter, so it is possible to make the macroscopic-control on the effect of kinetic characteristics on chromatographic system.展开更多
The theory of if-E curve in cyclic derivative chronopotentiometry is presented. Theoretical equations of if-E curves in the case of quasi-reversible and irreversible electrode reactions are deduced respectively.
The settlement of particles is of great importance in many areas. The accurate determination of drag coefficient and settling velocity in wide Reynolds number （Re） range remains a problem. In this paper, a series of...The settlement of particles is of great importance in many areas. The accurate determination of drag coefficient and settling velocity in wide Reynolds number （Re） range remains a problem. In this paper, a series of new formulas for drag coefficient of spherical particles based on theoretical laws, such as the Stokes law, the Oseen law, and the Goldstein law, were developed and fitted using 480 groups of experimental data （Re 〈 2 × 10^5）. The results show that the 2nd approximation of a rational function containing only one parameter can describe Co-Re relationship accurately over the whole Re range of 0-2× 10^5. The new developed formulas containing five parameters show higher goodness over wide Re range than presently existing equations. The introduction of the Oseen law is helpful for improving the fitting goodness of the empirical formulas. On the basis of one of the Oseen-based Co-Re formulas giving the lowest sum of squared relative errors Qover the whole Re range （Re 〈 2 × 10^5）, a general formula for settling velocity ut based on dimensionless parameters was proposed showing high goodness.展开更多
Aim To investigate the combined effect of hydroxypropyl-β-cyclodextrin （HP-β-CD） and media pH on the solubility of prostaglandin E1 （PGE1） and construct a theoretical equation for the drug solubility as a functi...Aim To investigate the combined effect of hydroxypropyl-β-cyclodextrin （HP-β-CD） and media pH on the solubility of prostaglandin E1 （PGE1） and construct a theoretical equation for the drug solubility as a function of HP-β-CD concentration and media pH. Methods The solubility of PGE1 under different pH conditions was determined. Then, the drug solubility in different concentrations of HP-β-CD acidic or pH neutral solutions was measured, respectively. Finally, a theoretical solubility equation for the drug as a function of HP-β-CD concentration and media pH was deduced and confirmed in experiment. Results PGEs was solubilized by HP-β-CD or by increasing media pH. The drug solubility as a function of HP-β-CD concentration was found to follow the AL-type complexation model in acidic or neutral pH media, suggesting that both the ionized and neutral drugs form 1：1 molecular ratio complexes. Conclusions The solubility of PGE1 may be improved by increasing media pH or by using HP-β-CD as a solubilizer. HP-β-CD and media pH can produce combined effect on the solubility of PGE1. The deduced equation for the drug solubility in this study effectively characterizes the roles of HP-β-CD and media pH in determining total solubility of the drug.展开更多
A simple theoretical equation of state is derived by applying the Tower-Well potential model about the molecular distribution based on the generalized van der Waals partition function. It needs only three molecular pa...A simple theoretical equation of state is derived by applying the Tower-Well potential model about the molecular distribution based on the generalized van der Waals partition function. It needs only three molecular parameters which have distinct physical meanings. The resulting equation of state predicts rather well the Vapor pressures, saturate liquid volumes, saturated vapor volumes and PVT thermodynamic properties of polar and structurally complex molecules over a wide temperature and pressure range.展开更多
文摘A simple model of chromatographic mechanical mechanism is present, and then a scrics of theoretical chromatographic equations and fundamental Formulae are derived. These theoretical equations and formulae not only reserve thermodynamic characteristics in the current fundamental chromatographic formulae, but also introduce one or more kinetic parameter, so it is possible to make the macroscopic-control on the effect of kinetic characteristics on chromatographic system.
基金Supported by the National Natural Science Foundation of China
文摘The theory of if-E curve in cyclic derivative chronopotentiometry is presented. Theoretical equations of if-E curves in the case of quasi-reversible and irreversible electrode reactions are deduced respectively.
基金financial support of the Natural Science Foundation of China (NSFC,No.50974094)
文摘The settlement of particles is of great importance in many areas. The accurate determination of drag coefficient and settling velocity in wide Reynolds number （Re） range remains a problem. In this paper, a series of new formulas for drag coefficient of spherical particles based on theoretical laws, such as the Stokes law, the Oseen law, and the Goldstein law, were developed and fitted using 480 groups of experimental data （Re 〈 2 × 10^5）. The results show that the 2nd approximation of a rational function containing only one parameter can describe Co-Re relationship accurately over the whole Re range of 0-2× 10^5. The new developed formulas containing five parameters show higher goodness over wide Re range than presently existing equations. The introduction of the Oseen law is helpful for improving the fitting goodness of the empirical formulas. On the basis of one of the Oseen-based Co-Re formulas giving the lowest sum of squared relative errors Qover the whole Re range （Re 〈 2 × 10^5）, a general formula for settling velocity ut based on dimensionless parameters was proposed showing high goodness.
文摘Aim To investigate the combined effect of hydroxypropyl-β-cyclodextrin （HP-β-CD） and media pH on the solubility of prostaglandin E1 （PGE1） and construct a theoretical equation for the drug solubility as a function of HP-β-CD concentration and media pH. Methods The solubility of PGE1 under different pH conditions was determined. Then, the drug solubility in different concentrations of HP-β-CD acidic or pH neutral solutions was measured, respectively. Finally, a theoretical solubility equation for the drug as a function of HP-β-CD concentration and media pH was deduced and confirmed in experiment. Results PGEs was solubilized by HP-β-CD or by increasing media pH. The drug solubility as a function of HP-β-CD concentration was found to follow the AL-type complexation model in acidic or neutral pH media, suggesting that both the ionized and neutral drugs form 1：1 molecular ratio complexes. Conclusions The solubility of PGE1 may be improved by increasing media pH or by using HP-β-CD as a solubilizer. HP-β-CD and media pH can produce combined effect on the solubility of PGE1. The deduced equation for the drug solubility in this study effectively characterizes the roles of HP-β-CD and media pH in determining total solubility of the drug.
文摘A simple theoretical equation of state is derived by applying the Tower-Well potential model about the molecular distribution based on the generalized van der Waals partition function. It needs only three molecular parameters which have distinct physical meanings. The resulting equation of state predicts rather well the Vapor pressures, saturate liquid volumes, saturated vapor volumes and PVT thermodynamic properties of polar and structurally complex molecules over a wide temperature and pressure range.
