Prediction of Infinite Dilution Activity Coefficients of Halogenated Hydrocarbons in Water

Geometrical optimization and electrostatic potential calculations have been performed for a series of halogenated hydrocarbons at the HF/Gen-6d level. A number of electrostatic potentials and the statistically based structural descriptors derived from these electrostatic potentials have been obtained. Multiple linear regression analysis and artificial neural network are employed simultaneously in this paper. The result shows that the parameters derived from electrostatic 2 potentials σtot^2, V s and ∑ Vs^＋, together with the molecular volume （Vine） can be used to express the quantitative structure-infinite dilution activity coefficients （γ^∞） relationship of halogenated hydrocarbons in water. The result also demonstrates that the model obtained by using BFGS quasiNewton neural network method has much better predictive capability than that from multiple linear regression. The goodness of the model has been validated through exploring the predictive power for the external test set. The model obtained via neural network may be applied to predict γ^∞ of other halogenated hydrocarbons not present in the data set.

Ant Colony Optimization as a Powerful Tool for Descriptor Selection in QSPR Study of Infinite Dilution Activity Coefficients of Halogenated Hydrocarbons in Water

A quantitative structure-property relationship （QSPR） study was suggested for the prediction of infinite dilution activity coefficients of halogenated hydrocarbons, γ∞ , in water at 298.15 K. After optimization of 3D geometry of the halogenated hydrocarbons with semi-empirical quantum chemical calculations at the AM1 level, different descriptors （1514 descriptors） were calculated by the HyperChem and Dragon softwares. A major problem of QSPR is the high dimensionality of the descriptor space; therefore, descriptor selection is the most important step. In this paper, an ant colony optimization （ACO） algorithm was proposed to select the best descriptors. Then the selected descriptors were applied for model development using multiple linear regression. The average absolute relative deviation and correlation coefficient for the training set were obtained as 4.36% and 0.951, respectively, while the corresponding values for the test set were 5.96% and 0.929, respectively. The results showed that the applied procedure is suitable for the prediction of γ∞ of halogenated hydrocarbons in water.

Aliphatic Halogenated Hydrocarbons: Report and Analysis of Liver Injury in 60 Patients

Background and Aims:Intoxications by aliphatic halogenated hydrocarbons(AHH),used as effective solvents,are rare and may cause life-threatening liver injury.Patients with acute intoxications by AHH received an innovative treatment.Methods:Analyzed were data of 60 patients intoxicated by AHH,such as dichloromethane(n=3),chloroform(n=2),carbon tetrachloride(n=12),1,2-dichloroethane(n=18),1,1,2-trichloroethane(n=2),trichloroethylene(n=2),tetrachloroethylene(n=13)or mixed AHH chemicals(n=8),who received a new treatment consisting of CO2-induced hyperventilation to accelerate toxin removal via the lungs.Results:Added to the inspiration air at a flow rate of 2-3 Liter min-1,CO2 increased the respiratory volume up to 25-30 Liter min-1,ensuring forced AHH exhalation.This CO2-induced hyperventilation therapy was commonly well tolerated by the 60 patients and lasted for 106.0±10.5 hours.In most cases,initially increased liver test results of aminotransferases normalized quickly under the therapy,and liver histology obtained at completion of the therapy revealed,in the majority of patients,normal findings or fatty changes,and rarely severe single cell necrosis but no confluent liver cell necrosis.Despite therapy,clinical outcome was unfavorable for 4/60 patients(6.7%)of the study cohort,due to single or combined risk factors.These included late initiation of the CO2-induced hyperventilation therapy,intentional intoxication,uptake of high amounts of AHH,concomitant ingestion of overdosed drugs,consumption of high amounts of alcohol,and history of alcohol abuse.Conclusions:For intoxications by AHH,effective therapy approaches including forced hyperventilation to increase toxin removal via the lungs are available and require prompt initiation.