Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (Koc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the ...Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (Koc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to 2 mg/L. In comparing with existing methods of Koc, SCLC possesses rapid, online and accurate characteristics.展开更多
Quantum chemistry parameters of 22 fluorobenzenes were computed at six levels using Hartree-Fock and DFT methods. Based on the experimental data of n-octanol/water partition coefficient (lgKow), a three-parameter (dip...Quantum chemistry parameters of 22 fluorobenzenes were computed at six levels using Hartree-Fock and DFT methods. Based on the experimental data of n-octanol/water partition coefficient (lgKow), a three-parameter (dipole moments (μ), zero point energy (ZPE) and free energy (G°)) quantitative correlation equation that can predict lgKow was developed using structural and thermodynamic parameters as theoretical descriptors. Similarly, based on experimental data of soil organic carbon sorption coefficient (lgKoc), the other three-parameter (the most negative atomic net charge of molecule (q-), dipole moments (μ) and molecular volume (Vi)) quantitative correlation equation that can predict lgKoc was given. Quantitative correlation equations based on B3LYP/6- 311G** calculation were validated by VIF (variance inflation factors) and t-test and used to predict lgKow and lgKoc of a series of compounds. The result showed that the correlation and prediction ability of lgKoc equations based on three levels of HF/STO-3G, B3LYP/6-31G* and B3LYP/6- 311G** are all more advantageous than those based on AM1.展开更多
On the basis of Jacobson’s free length theory and the theory of pressure coefficient and temperature coefficient of free length in liquids, the relationship between the pressure coefficient of ultrasonic velocity and...On the basis of Jacobson’s free length theory and the theory of pressure coefficient and temperature coefficient of free length in liquids, the relationship between the pressure coefficient of ultrasonic velocity and the pressure coefficient of free length, and the relationship between the temperature coefficient of ultrasonic velocity and the temperature coefficient of free length were studied. Relevant equations were given, and the pressure coefficient and temperature coefficient of ultrasonic velocity were calculated, which are in agreement with the measured values.展开更多
基金Bayer AG and Chinese Academy of Agricultural Sciences for kindly supplying the pesticides.
文摘Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (Koc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to 2 mg/L. In comparing with existing methods of Koc, SCLC possesses rapid, online and accurate characteristics.
基金Project supported by the Chinese Postdoctoral Science Foundation (No. 2003033486) and the National Natural Science Foundation of China (20477018)
文摘Quantum chemistry parameters of 22 fluorobenzenes were computed at six levels using Hartree-Fock and DFT methods. Based on the experimental data of n-octanol/water partition coefficient (lgKow), a three-parameter (dipole moments (μ), zero point energy (ZPE) and free energy (G°)) quantitative correlation equation that can predict lgKow was developed using structural and thermodynamic parameters as theoretical descriptors. Similarly, based on experimental data of soil organic carbon sorption coefficient (lgKoc), the other three-parameter (the most negative atomic net charge of molecule (q-), dipole moments (μ) and molecular volume (Vi)) quantitative correlation equation that can predict lgKoc was given. Quantitative correlation equations based on B3LYP/6- 311G** calculation were validated by VIF (variance inflation factors) and t-test and used to predict lgKow and lgKoc of a series of compounds. The result showed that the correlation and prediction ability of lgKoc equations based on three levels of HF/STO-3G, B3LYP/6-31G* and B3LYP/6- 311G** are all more advantageous than those based on AM1.
文摘On the basis of Jacobson’s free length theory and the theory of pressure coefficient and temperature coefficient of free length in liquids, the relationship between the pressure coefficient of ultrasonic velocity and the pressure coefficient of free length, and the relationship between the temperature coefficient of ultrasonic velocity and the temperature coefficient of free length were studied. Relevant equations were given, and the pressure coefficient and temperature coefficient of ultrasonic velocity were calculated, which are in agreement with the measured values.
