Yung-Shuen Shen

The effect of light absorbance on the decomposition of chlorophenols by ultraviolet radiation and U.V./H2O2 processes

The effect of light absorbance on the decomposition of chlorophenols in aqueous solution by ultraviolet radiation and u.v./H2O2 oxidation was studied. The light absorbance and photolytic properties of chlorophenols and H2O2 were found to be highly dependent on the solution pH and can be adequately described with the two species distribution model. For u.v./H2O2 process, the individual contribution to the decomposition of chlorophenols by direct photolysis and free hydroxyl radical destruction was differentiated by studying the u.v. light absorbance of various chlorophenols and H2O2 species.

Decomposition of gaseous trichloroethylene in a photoreactor with TiO2-coated nonwoven fiber textile

Abstract The decomposition of gaseous trichloroethylene by UV/TiO2 process in an annular photoreactor fixed with TiO2-coated nonwoven fiber textile was studied under various UV light intensities, humidities, oxygen contents and retention times of carrier gases. Experimental results indicated that the photocatalysis by UV/TiO2 process is technically feasible to decompose trichloroethylene in air streams. A design equation combining the equations of continuity and surface catalytic kinetics was developed for describing the decomposition of trichloroethylene in air streams by UV/TiO2 process at various operating conditions.

CCL5 and CCR5 Interaction Promotes Cell Motility in Human Osteosarcoma

Background Osteosarcoma is characterized by a high malignant and metastatic potential. CCL5 (previously called RANTES) was originally recognized as a product of activated T cells, and plays a crucial role in the migration and metastasis of human cancer cells. It has been reported that the effect of CCL5 is mediated via CCR receptors. However, the effect of CCL5 on migration activity and integrin expression in human osteosarcoma cells is mostly unknown. Methodology/Principal Findings Here we found that CCL5 increased the migration and expression of αvβ3 integrin in human osteosarcoma cells. Stimulation of cells with CCL5 increased CCR5 but not CCR1 and CCR3 expression. CCR5 mAb, inhibitor, and siRNA reduced the CCL5-enhanced the migration and integrin up-regulation of osteosarcoma cells. Activations of MEK, ERK, and NF-κB pathways after CCL5 treatment were demonstrated, and CCL5-induced expression of integrin and migration activity was inhibited by the specific inhibitor and mutant of MEK, ERK, and NF-κB cascades. In addition, over-expression of CCL5 shRNA inhibited the migratory ability and integrin expression in osteosarcoma cells. Conclusions/Significance CCL5 and CCR5 interaction acts through MEK, ERK, which in turn activates NF-κB, resulting in the activations of αvβ3 integrin and contributing the migration of human osteosarcoma cells.

Applying Bayesian belief networks to health risk assessment

The health risk of noncarcinogenic substances is usually represented by the hazard quotient (HQ) or target organ-specific hazard index (TOSHI). However, three problems arise from these indicators. Firstly, the HQ overestimates the health risk of noncarcinogenic substances for non-critical organs. Secondly, the TOSHI makes inappropriately the additive assumption for multiple hazardous substances affecting the same organ. Thirdly, uncertainty of the TOSHI undermines the accuracy of risk characterization. To address these issues, this article proposes the use of Bayesian belief networks (BBN) for health risk assessment (HRA) and the procedure involved is developed using the example of road constructions. According to epidemiological studies and using actual hospital attendance records, the BBN-HRA can specifically identify the probabilistic relationship between an air pollutant and each of its induced disease, which can overcome the overestimation of the HQ for non-critical organs. A fusion technique of conditional probabilities in the BBN-HRA is devised to avoid the unrealistic additive assumption. The use of the BBN-HRA is easy even for those without HRA knowledge. The input of pollution concentrations into the model will bring more concrete information on the morbidity and mortality rates of all the related diseases rather than a single score, which can reduce the uncertainty of the TOSHI.

Decomposition of gas-phase trichloroethene by the UV/TiO2 process in the presence of ozone

The decomposition of gas-phase trichloroethene (TCE) in air streams by direct photolysis, the UV/TiO2 and UV/O3 processes was studied. The experiments were carried out under various UV light intensities and wavelengths, ozone dosages, and initial concentrations of TCE to investigate and compare the removal efficiency of the pollutant. For UV/TiO2 process, the individual contribution to the decomposition of TCE by direct photolysis and hydroxyl radicals destruction was differentiated to discuss the quantum efficiency with 254 and 365 nm UV lamps. The removal of gaseous TCE was found to reduce by UV/TiO2 process in the presence of ozone possibly because of the ozone molecules could scavenge hydroxyl radicals produced from the excitation of TiO2 by UV radiation to inhibit the decomposition of TCE. A photoreactor design equation for the decomposition of gaseous TCE by the UV/TiO2 process in air streams was developed by combining the continuity equation of the pollutant and the surface catalysis reaction rate expression. By the proposed design scheme, the temporal distribution of TCE at various operation conditions by the UV/TiO2 process can be well modeled.

Mercury removal from aqueous solutions by zinc cementation

The main purpose of this research is to study the addition effect of the surfactant and other operating factors on the treatment of wastewater containing mercury ions in aqueous solution by cementation with sacrificing metal, zinc. The removal of mercury ions from aqueous solutions by cementation of zinc powder was found to be a function of solution pH and temperature, amount of zinc, concentration of mercury ion, contact time and the addition of several organic surfactants. Cementation of mercury was shown to be a feasible process to achieve a very high degree of mercury removal over a broad operational range within a fairly reasonable contact time. The reaction rate is approximately first order with respect to the concentration of mercury ion in aqueous solution. Among the surfactants used in this study, only the presence of SDS, an anionic surfactant, slightly enhanced the cementation rate of mercury. The presence of CTAB and Triton-X100 retarded the cementation of mercury by zinc.

Decomposition of phenols in aqueous solution by a UV/O3 process

Abstract The decomposition of several non‐biodegradable phenols by the UV/O3 and ozonation processes was studied and compared under various solution pH values, O3 input mass flow rates and UV intensities to investigate the removal efficiencies of reactants and organic intermediates. The decomposition rate of phenols by the UV/O3 process was found to increase with increasing O3 input dosage, light intensity and solution pH value. The mineralization efficiencies of phenols in aqueous solution would be above 98% under adequate reaction conditions within three hours, but would be retarded for alkaline solutions because of the dissolution of CO2 formed by mineralization of phenols. The increment of ozone input dosage had little effect on the mineralization of organic intermediates at the latter course of the reaction. The order of the decomposition rate of the phenols used in this research was 2,4‐dichlorophenol > 2‐chlorophenol > 2‐nitrophenol for low and neutral pH solutions, whereas they were nearly alike f...

A study on the cadmium removal from aqueous solutions by zinc cementation

The cementation of cadmium ions from aqueous solutions on zinc powder was studied as a function of solution pH and temperature, amount of zinc, concentration of cadmium ion, contact time, and the addition of several organic compounds, including surfactant and chelating agent. Cementation of cadmium was shown to be a feasible treatment process to achieve a high degree of cadmium removal within a fairly reasonable contact time. The deposition of cadmium and zinc consumption are highly dependent on solution pH conditions and is most practically operated at weak acidic conditions of pH 4–5. The reaction rate is approximately first order with respect to both the amount of zinc and the concentration of cadmium ion. Among the surfactants used in this study, only the presence of sodium dodecyl sulfonate, an anionic surfactant, noticeably enhanced the cementation rate of cadmium by zinc powder. The presence of ethylene-diaminetetraacetic acid (EDTA) in aqueous solutions inhibited the removal of cadmium by zinc due to the possible formation of Cd–EDTA chelates, which possess higher redox potential than that of free cadmium ions.

Photooxidation Contribution Study on the Decomposition of Azo Dyes in Aqueous Solutions by VUV-Based AOPs

The effects of pH value, VUV intensity, initial dye concentration, initial H2O2 concentration, and TiO2 loading dose on the degradation of three azo dyes: acid Orange 8, acid Blue 29, and acid Blue 113 were studied to explore and compare the treatment efficiencies among the adopted AOPs. It was found that pH played an important role in the degradation of dyes using VUV irradiation. For VUV/H2O2, VUV/TiO2, and VUV/TiO2/H2O2 processes, the decoloration rates of the three azo dyes were more efficient under acidic conditions relative to alkaline conditions. The degradation rates of dyes increased with increasing concentrations of H2O2, but reaction rates were retarded at high concentrations of H2O2 because the H2O2 compound acted as a scavenger of the hydroxyl radical. In this paper, three azo dyes were decomposed efficiently by VUV irradiation only demonstrating the effectiveness of VUV direct photolysis.

Treatment of gas-phase trichloroethene in air by the UV/O3 process

Abstract The reaction behavior of the photolysis of gas-phase trichloroethene (TCE) in the presence of ozone was studied. The temporal distributions of TCE and chlorinated intermediates under various operating conditions were studied and described in terms of a two-step consecutive dechlorination kinetic model. The enhancement of UV light intensity would promote the decomposition of TCE more effectively than the addition of ozone. The presence of ozone contributed more to the dechlorination of chlorinated intermediates than of TCE by the UV/O3 process.