Remediation of heavy metal contaminated soils via integrated electrochemical processes

The thrust of this study is to develop an in-situ method/technique capable of modifying the contaminated soil environment and maximizing contaminant extraction. Contaminated soils were compacted in electrokinetic cells to densities similar to natural field conditions. Conditioning fluids were used during the application of a direct current to solubilize the precipitated forms of heavy metals. Mobilization of contaminants as a function of time was quantified by analysing metal ion concentrations in the extracted effluents at both the anode and cathode and in the compacted specimens. For each conditioning fluid used, the removal efficiencies were evaluated based on both effluent and soil concentrations.     

Kinetic adsorption of application of carbon nanotubes for Pb(Ⅱ) removal from aqueous solution

The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(Ⅱ) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coeffcients from Langmuir isotherm model indicates the strong adsorptions of Pb(Ⅱ) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates tha...     

Antenatal corticosteroids and outcomes in gastroschisis: A multicenter retrospective cohort study

Objective

In gastroschisis, there is evidence to suggest that gut dysfunction develops secondary to bowel inflammation; we aimed to evaluate the effect of maternal antenatal corticosteroids administered for obstetric reasons on time to full enteral feeds in a multicenter cohort study of gastroschisis infants.

Methods

A three center, retrospective cohort study (1992-2013) with linked fetal/neonatal gastroschisis data was conducted. The primary outcome measure was time to full enteral feeds (a surrogate measure for bowel function) and secondary outcome measure was length of hospital stay. Analysis included Mann-Whitney and Cox regression.

Results

Of 500 patients included in the study, 69 (GA at birth 34 [25-38] weeks) received antenatal corticosteroids and 431 (GA at birth 37 [31-41] weeks) did not. Antenatal corticosteroids had no effect on the rate of reaching full feeds (Hazard ratio HR 1.0 [95% CI: 0.8-1.4]). However, complex gastroschisis (HR 0.3 [95% CI: 0.2-0.4]) was associated with an increased time to reach full feeds and later GA at birth (HR 1.1 per week increase in GA [95% CI: 1.1-1.2]) was associated with a decreased time to reach full feeds.

Conclusion

Maternal antenatal corticosteroids use, under current antenatal steroid protocols, in gastroschisis is not associated with an improvement in neonatal outcomes such as time to full enteral feeds or length of hospital stay.     

Pesticide resistance externalities and optimal mosquito management

A simultaneous equation model of the behavior of a mosquito abatement district based on biological and economic data is presented. Results indicate high long term costs if heavy reliance on chemical pesticide control methods continue, due to a pesticide resistance buildup in the mosquito populations. Physical source reduction methods were shown to be more efficient both in the short and long run. A linear programming model is presented which optimizes the inix of chemical and physical control methods. Results indicate increasing costs of mosquito abatement as pesticide effectiveness declines.     

Appraisal of methane production and anaerobic fermentation kinetics of livestock manures using artificial neural networks and sinusoidal growth functions

This study aimed to perform a comparative analysis of the performance of five models (Gompertz, logistic, Richards, the first-order, artificial neural networks) in predicting methane production rate from anaerobic digestion of livestock manures. The input variables were fermentation time, digestion temperature, biogas temperature, ambient temperature, pH, and specific biogas production rate. The physicochemical compositions of cow manure and sheep manure showed that volatile solid (VS) contents were close to each other in manure compositions (77.6% and 64.7%, respectively), while the potential of methane production from cow manure (673.44 mL CH₄/g VS) was greater than that from sheep manure (320.32 mL CH₄/g VS). The determination coefficients (R²) for logistic function, Gompertz, Richards, the first-order, and ANN models were obtained as 0.968, 0.967, 0.975, 0.825, and 0.995 for the cow manure, respectively. In case of the sheep manure, the R² values obtained from these models were 0.976, 0.979, 0.981, 0.968 and 0.991, respectively. Although the determination coefficients of all models were in satisfactory agreement with the experimental data, the ANN model showed competitive lower RMSE values of 0.111 and 0.164 for cow and sheep manure data sets, respectively, indicating its superior performance than other models.