Efficacy of lidocaine spray as topical anaesthesia for outpatient rigid cystoscopy in women: A prospective, randomized, double-blind trial

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• 作者：J.H. Choe ; K.W. Kwak ; J.H. Hong ; H.M. Lee
• 关键词：Vehicle emissions ; Catalytic reduction of nitrogen oxides ; Reactive nitrogen compounds (RNCs) ; Secondary pollutants of three-way catalysts ; Time-resolved exhaust analysis ; Chemical ionization-mass spectrometry (CI-MS)
• 刊名：Acute Pain
• 出版年：2008
• 出版时间：June 2008
• 年：2008
• 卷：10
• 期：2
• 页码：98
• 全文大小：35 K

文摘

Vehicular emissions of reactive nitrogen compounds (RNCs) such as nitric oxide (NO), nitrogen dioxide (NO₂), and ammonia (NH₃) have a substantial impact on urban air quality. NO and NO₂ support the photochemical formation of ozone, and NH₃ is involved in the atmospheric formation of secondary aerosols. Vehicular NO is mainly formed during combustion, whereas NO₂ and NH₃ are both secondary pollutants of the catalytic converter systems. Herein we report on tail-pipe RNC emissions of gasoline-fueled Euro-3- and Euro-4-passenger cars at transient driving from 0 to 150 km h⁻¹. Two sets of 10 in-use vehicles with comparable engine size and mileage were studied with time-resolved chemical ionization-mass spectrometry (CI-MS). Each vehicle was tested in 7 different driving cycles including the legislative European (EDC) and the US FTP-75 driving cycles. Mean emission factors (EFs) for different traffic situations are reported and effects of cold start, velocity, acceleration, and deceleration are discussed. Furthermore, critical operating conditions supporting the de novo formation of NH₃ have been identified. In the EDC, mean NO- and NH₃-EFs of 57±26 and 16±12 mg km⁻¹ were obtained for Euro-3-vehicles; those of the Euro-4-technology were lower by about 25 % and 33 % at the levels of 43±46 and 10±7 mg km⁻¹, respectively. NO₂ emissions of the investigated three-way catalyst (TWC) vehicles accounted for <1 % of the detected RNCs, whereas NH₃ was found to be the dominant RNC for most vehicle conditions. Molar NH₃ proportions varied from about 0.4–0.8, as soon as catalyst light-off occurred. NO was found in large excess only during the cold-start period. Catalyst light-off is indicated by a fast transition from NO- to NH₃-rich exhaust. Velocity and acceleration had pronounced effects on the RNC emission characteristics. Mean velocity-dependent EFs for NO and NH₃ varied by about one order of magnitude from 10 to 74 and 15 to 161 mg km⁻¹ for Euro-3-vehicles and from 12 to 44 and 7 to 144 mg km⁻¹ for the Euro-4 fleet. We conclude that the investigated Euro-3- and Euro-4-vehicles are mainly operated under slightly reducing conditions, where the NH₃ emissions dominate over those of the NO. Under these conditions, both vehicle fleets on an average fulfilled the valid Euro-3 and Euro-4 limits for nitrogen oxides (NO_x) of 150 and 80 mg km⁻¹, respectively (as NO₂ equivalents).