Nonthermal plasma coupled with liquid-phase UV/Fe-C for chlorobenzene removal.

Catalyst poisoning problems limit the application of gas-solid non-thermal plasma (NTP) catalyzed decomposition of chlorinated volatile organic compounds (Cl-VOCs). To mitigate the catalyst deactivation, catalyst iron-loaded activated carbon (Fe-C) was added to the UV-activated liquid phase downstream of the NTP reactor (NTP + UV/Fe-C(L)) for the degradation of chlorobenzene (CB) in this study. The CB removal efficiency and mineralization efficiency (MR) of NTP + UV/Fe-C(L) were up to 94% and 68%, respectively, which were increased by 39% and 30% compared with the single NTP system. Compared with the conventional gas-solid NTP + UV/Fe-C(S) system, the stability of the NTP + UV/Fe-C(L) system was significantly improved due to the dissolved organic intermediates and low residuals on the catalyst surface. Reactive oxygen species ·OH and ·O2- dominated the decomposition of CB in the liquid phase, and with the help of UV, much more ·OH and ·O2- were produced by Fe-C catalytic O3. In addition, Fe-C improved the removal of CB by increasing its absorption mass transfer coefficient from 0.0016 to 0.0157 s-1. The degradation pathway of CB in the NTP + UV/Fe-C(L) system was proposed based on the detected organic intermediates. Overall, this study provides a new tactic to solve the catalyst poisoning problem in the NTP catalytic oxidation of Cl-VOCs.

Dielectric barrier discharge coupled with Fe2+, Mn2+ and Cu2+ scrubbing for toluene removal.

By-product ozone emission is one of the challenges for applying dielectric barrier discharge (DBD) technology for volatile organic compounds (VOCs) removal. In this study, a DBD reactor followed by a wet scrubber (WS) containing a solution of metal ions (Fe2+/Mn2+/Cu2+) was used to reuse ozone for further oxidation of typical VOC toluene. Compared with the degradation effect of the DBD reactor alone, DBD coupled WS/iron system not only improved the toluene removal efficiency but also significantly reduced the ozone emission. The ozone removal efficiency reached as high as 98% in the DBD coupled WS/Fe2+ system. Electron paramagnetic resonance (EPR) tests showed that ozone was converted into radicals such as hydroxyl radicals in Fe2+ and Cu2+ solution, which further oxidized toluene in WS/iron. Quenching experiments showed that the contribution for toluene degradation by radicals was up to 75% and 62% in Fe2+ and Mn2+ reactor, respectively. This study demonstrates that the DBD coupled WS system has the potential to be an environmentally friendly technology for gaseous VOCs removal.

An Electrochemical Sensor Based on Electropolymerization of ß-Cyclodextrin on Glassy Carbon Electrode for the Determination of Fenitrothion.

An electrochemical sensor enabled by electropolymerization (EP) of ß-cyclodextrin on glassy carbon electrode (ß-CDP/GCE) is built for the determination of fenitrothion (FNT). The effects of the EP cycles, pH value, and enrichment time on the electrochemical response of FNT were studied. With the optimum conditions, good linear relationships between the current of the reduction peak of the nitroso derivative of FNT and the concentration are obtained in the range of 10-150 and 150-4000 ng/mL, with a detection limit of 6 ng/mL (S/N = 3). ß-CDP/GCE also exhibits a satisfactory applicability in cabbage and tap water, with recovery values between 98.43% and 112%. These outstanding results suggest that ß-CDP/GCE could be a new effective alternative for the determination of FNT in real samples.

Kinetics study on non-thermal plasma mineralization of adsorbed toluene over γ-Al2O3 hybrid with zeolite.

Non-thermal plasma mineralization of the adsorbed toluene over γ-Al2O3 hybrid with 13X, ZSM-5, and HY was investigated in a sequential adsorption and plasma oxidation system. The γ-Al2O3-13X was shown to have a better plasma oxidation performance with fewer by-products as compared to γ-Al2O3-ZSM-5 and γ-Al2O3-HY, which was due to its better discharge performance and O3 decomposition ability. For all of the tested materials, the plasma mineralization of the adsorbed toluene process had a good match with the pseudo-second-order kinetic model: kt = 1/n - 1/no, where n0 and n are the amount of adsorbed toluene (mmol) at discharge time = 0 and t, respectively. The overall reaction constant (k) was shown to be affected by the packing materials. The reason for the kinetic model following the pseudo-second-order in the sequential process was analyzed based on the chemical reaction and mineralization mechanism.

Extended High-Frequency Audiometry (9-20 kHz) in Civilian Pilots.

INTRODUCTION: The greater sensitivity of extended high-frequency audiometry (EHFA) than conventional audiometry (CA) for identifying early changes in hearing has been well documented in previous literature. However, no studies about EHFA were conducted on civilian pilots. The aim of this study was to investigate the usefulness of EHFA as an assay to evaluate civilian pilots' hearing status. METHODS: An observational cross-sectional study was conducted on 134 civilian pilots (case group) and 101 subjects without noise exposure (control group). All of the subjects underwent CA (0.25-8 kHz) and EHFA (9-20 kHz). The potential of EHFA for identifying early changes in hearing was assessed. RESULTS: The two audiometric tools both showed significantly higher hearing thresholds in the case group for most of the frequencies tested, but the differences were more obvious for EHFA. Compared with the control group, the average thresholds in the case group increased 3.15 dB at CA and 7.83 dB at EHFA for age 20-29. The number was 2.37 dB and 9.90 dB for age 30-39; 3.80 dB and 8.19 dB for age 40-49; and 10.84 dB and 16.86 dB for age 50-59. There were 74.6% of pilots who had hearing loss in at least in one ear and at one frequency in CA and 94.8% at EHFA. Significant differences in EHFA were observed also between pilots and their controls with normal hearing thresholds at CA. CONCLUSIONS: EHFA is more sensitive than CA and could be useful in detecting subclinical changes of hearing in civilian pilots.Ma F, Gong S, Liu S, Hu M, Qin C, Bai Y. Extended high-frequency audiometry (9-20 kHz) in civilian pilots. Aerosp Med Hum Perform. 2018; 89(7):593-600.

Removal of toluene by sequential adsorption-plasma oxidation: Mixed support and catalyst deactivation.

A sequential adsorption-plasma oxidation system was used to remove toluene from simulated dry air using γ-Al2O3, HZSM-5, a mixture of the two materials or their supported Mn-Ag catalyst as adsorbents under atmospheric pressure and room temperature. After 120min of plasma oxidation, γ-Al2O3 had a better carbon balance (∼75%) than HZSM-5, but the CO2 yield of γ-Al2O3 was only ∼50%; and there was some desorption of toluene when γ-Al2O3 was used. When a mixture of HZSM-5 and γ-Al2O3 with a mass ratio of 1/2 was used, the carbon balance was up to 90% and 82% of this was CO2. The adsorption performance and electric discharge characteristics of the mixed supports were tested in order to rationalize this high COx yield. After seven cycles of sequential adsorption-plasma oxidation, support and Mn-Ag catalyst deactivation occurred. The support and catalyst were characterized before and after deactivation by SEM, a BET method, XRD, XPS and GC-MS in order to probe the mechanism of their deactivation. 97.6% of the deactivated supports and 76% of the deactivated catalysts could be recovered by O2 temperature-programmed oxidation.

Toluene removal by sequential adsorption-plasma catalytic process: Effects of Ag and Mn impregnation sequence on Ag-Mn/γ-Al2O3.

A series of Ag-Mn/γ-Al2O3 were prepared under different Ag/Mn impregnation sequence and tested in the sequential adsorption-plasma catalytic removal of toluene. When Mn was impregnated first, the resulting catalyst, Ag-Mn(F)/γ-Al2O3, had longer breakthrough time, gave less emission of toluene, had higher CO2 selectivity, and had better carbon balance and COx yield compared to catalysts prepared via other impregnation sequences. After 120 min of NTP treatment, the carbon balance of Ag-Mn(F)/γ-Al2O3 was 91%, with 87% as COx contributions. A Brunauer-Emmett-Teller (BET) analysis and X-ray photoelectron spectroscopy (XPS) results show that, the impregnation sequence impacts the BET surface area and the ratio and existing state of Ag on the surface of the catalysts. The longer breakthrough time when using Ag-Mn(F)/γ-Al2O3 as catalyst is attributed to the large amount of Ag(+) on the surface. Ag(+) is a new active site for toluene adsorption. When Ag was impregnated first (Ag(F)-Mn/γ-Al2O3) or Ag and Mn co-impregnated (Ag-Mn-C/γ-Al2O3), the predominant specie was Ag(+). Both Ag(0) and Ag(+) species were detected on Ag-Mn(F)/γ-Al2O3. Ag(0) cooperation with MnOx may promote the migration of surface active oxygen. This would facilitate the oxidation of adsorbed toluene with CC bond already weakened by Ag(+) and would result in higher CO2 selectivity and better carbon balance as seen in the Ag-Mn(F)/γ-Al2O3 system.

[Expression and significance of IFN-γ and IL-4 in the effusion and peripheral blood of chronic otitis media with effusion patients].

OBJECTIVE: To explore the shift of Th2/Th1 type cytokine profiles in middle ear and peripheral blood of chronic otitis media with effusion (COME) patients. METHODS: Middle ear effusions (MEEs) and peripheral bloods were collected from 30 COME patients between April 2011 and July 2012 at Department of Otolaryngology, Beijing Tongren Hospital, Capital Medical University. Peripheral blood samples were collected from 20 healthy controls. The expressions of IFN-γ (Th1 cytokine) and IL-4 (Th2 cytokine) in peripheral blood and middle ear fluid were assessed by flow cytometry and cytometric bead array. The expression levels of cytokines in peripheral blood were compared between patient and control groups. Moreover, the levels of cytokines in the Middle ear fluid and the supernatant of COME patients were also compared. RESULTS: Compared to the control group, the level of IL-4 in peripheral blood of COME patients significantly increased (0.7% ± 0.8% vs 2.4% ± 4.5%, P < 0.05) . The ratio of IFN-γ positive cells/IL-4 positive cells was significantly lower in peripheral blood of COME patients than that of control group (17 ± 13 vs 35 ± 19, P < 0.05) . However, the level of IFN-γ showed no significant difference between two groups (12% ± 8% vs 13% ± 8%, P > 0.05) . The levels of IL-4 and IFN-γ in middle ear fluid and the supernatant of the case group showed no significant difference. CONCLUSIONS: COME may be a Th2 predominant disease. Th1/Th2 imbalance is probably involved in the pathogenesis of COME. The role of the allergic reaction in middle ear microenvironment remains uncertain.