scholarly journals Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China

2021 ◽  
Vol 21 (19) ◽  
pp. 15135-15152
Author(s):  
Mengmeng Li ◽  
Zihan Zhang ◽  
Quan Yao ◽  
Tijian Wang ◽  
Min Xie ◽  
...  
Keyword(s):  
Emission Reduction ◽  
Fine Particulate Matter ◽  
Eastern China ◽  
Yangtze River Delta ◽  
Nitrate Pollution ◽  
Nox Emission ◽  
Nox Emissions ◽  
Nonlinear Responses ◽  
Emission Controls ◽  
Reduction Of Nox

Abstract. Nitrate is an increasingly important component of fine particulate matter (PM2.5) in Chinese cities. The production of nitrate is not only related to the abundance of its precursor, but it is also supported by the atmospheric photochemical oxidants, raising a new challenge for the current emission control actions in China. This paper uses comprehensive measurements and a regional meteorology–chemistry model with optimized mechanisms to establish the nonlinear responses between particulate nitrate and the emission controls of nitrogen oxides (NOx) in the megalopolises of China. Nitrate is an essential component of PM2.5 in eastern China, accounting for 9.4 %–15.5 % and 11.5 %–32.1 % of the PM2.5 mass for the warm and cold seasons. The hypothetical NOx emission reduction scenarios (−10 % to −80 %) during summer–autumn result in almost linearly lower PM2.5 by −2.2 % in Beijing–Tianjin–Hebei (BTH) and −2.9 % in Yangtze River Delta (YRD) per 10 % reduction of NOx emissions, whereas they lead to a rather complicated response of PM components in winter. Wintertime nitrate is found to increase by +4.1 % in BTH and +5.1 % in YRD per 10 % reduction of NOx emissions, with nearly unchanged nitric acid (HNO3) and higher dinitrogen pentoxide (N2O5) intermediate products produced from the increased atmospheric oxidant levels. An inflexion point appears at 30 %–50 % NOx emission reduction, and a further reduction in NOx emissions is predicted to cause −10.5 % reduction of nitrate for BTH and −7.7 % for YRD per 10 % reduction of NOx emissions. In addition, the 2012–2016 NOx control strategy actually leads to no changes or even increases of nitrate in some areas (8.8 % in BTH and 14.4 % in YRD) during winter. Our results also emphasize that ammonia (NH3) and volatile organic compounds (VOCs) are effective in controlling nitrate pollution, whereas decreasing the sulfur dioxide (SO2) and NOx emissions may have counterintuitive effects on nitrate aerosols. This paper helps understand the nonlinear aerosol and photochemistry feedbacks and defines the effectiveness of proposed mitigations for the increasingly serious nitrate pollution in China.

scholarly journals Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China

2021 ◽  
Author(s):  
Mengmeng Li ◽  
Zihan Zhang ◽  
Tijian Wang ◽  
Min Xie ◽  
Shu Li ◽  
...  
Keyword(s):  
Emission Reduction ◽  
Fine Particulate Matter ◽  
Eastern China ◽  
Yangtze River Delta ◽  
Nox Emission ◽  
Nox Emissions ◽  
Dinitrogen Pentoxide ◽  
Nonlinear Responses ◽  
Emission Controls ◽  
Nox Control

Abstract. Nitrate is an increasingly important component of fine particulate matter (PM2.5) in Chinese cities. The production of nitrate is not only related to the abundance of its precursor, but also supported by atmospheric photochemical oxidants. The control of nitrogen oxides (NOx) emissions may thereby lead to nonlinear changes of nitrate concentrations, raising a new challenge to the current emission control actions in China. This paper uses comprehensive measurements and a regional meteorology-chemistry model with optimized mechanisms to establish the nonlinear responses between particulate nitrate and NOx emission controls in the megalopolises of China. Nitrate is an essential component of PM2.5 in eastern China, accounting for 9.4–15.5 % and 11.5–32.1 % of the PM2.5 mass for the warm and cold seasons. The hypothetical NOx emission reduction scenarios (−10 %~−80 %) during summer-autumn result in almost linearly lower PM2.5 by −2.65 % in Beijing-Tianjin-Hebei (BTH) and −2.79 % in Yangtze River Delta (YRD) per 10 % cut of NOx emissions, whereas they increase the oxidant levels and lead to a rather complicated response of PM components in winter. Wintertime nitrate is found to increase by 4.28 % in BTH and 4.60 % in YRD, with higher dinitrogen pentoxide (N2O5) intermediate products produced from increased ozone introduced by lower NOx emissions. An inflexion point appears at 40–50 % NOx emission reduction, and a further cut in NOx emission is predicted to cause −8.74 % reduction of nitrate for BTH and −10.59 % for YRD per 10 % cut of NOx emissions. In addition, the 2012–2016 NOx control strategy actually leads to no change or even increase of nitrate in some areas (8.82 % in BTH and 14.41 % in YRD) during winter. This paper helps understand the nonlinear aerosol and photochemistry feedbacks, and defines the effectiveness of proposed mitigations for the increasingly serious nitrate pollution in China.

Investigation on NOx of a Low Emission Combustor Design With Multihole Premixer-Prevaporizer

2004 ◽  
Author(s):  
Yuzhen Lin ◽  
Yunhui Peng ◽  
Gaoen Liu
Keyword(s):  
Great Influence ◽  
Nox Emission ◽  
Emissions Reduction ◽  
Inlet Temperature ◽  
Main Stage ◽  
Nox Emissions ◽  
Baseline Design ◽  
Air Mixing ◽  
Reduction Of Nox ◽  
Two Stages

A low NOx emission combustor design was presented in this paper. The design features the premixer-prevaporizer tube with multihole and two stages arranged radially in line, with the outer stage being pilot stage and inner stage being main stage. The multihole premixer and prevaporizer is a part of main stage. The results of NOx emission were provided and also compared with the baseline design that the premixer and prevaporizer tube without multihole. The double swirler prefilming airblast atomizer was installed in the premixed prevaporized duct entrance. The mean drop size and radial fuel flux distribution were measured to determine proper configurations of the multihole premixer-prevaporizer. NOx emission investigations were carried out using a test combustor with one pilot stage and one main stage under the operating condition of high inlet temperature (800K) and inlet air pressure was atmospheric pressure. The experiment results demonstrated large NOx emissions reduction of the multihole premixer-prevaporizer compared with the baseline design. The more even fuel-air mixing, which was gained by the multiple jets, intensified the fuel and air mixing within the premixer-prevaporizer, resulted in the large reduction of NOx emission. The configurations of multihole premixer-prevaporizer had great influence on NOx emissions reduction.

scholarly journals Comparison of Ozone and PM2.5 Concentrations over Urban, Suburban, and Background Sites in China

2020 ◽  
Vol 37 (12) ◽  
pp. 1297-1309
Author(s):  
Lan Gao ◽  
Xu Yue ◽  
Xiaoyan Meng ◽  
Li Du ◽  
Yadong Lei ◽  
...  
Keyword(s):  
Urban Areas ◽  
Surface Ozone ◽  
Fine Particulate Matter ◽  
Eastern China ◽  
Yangtze River Delta ◽  
River Delta ◽  
Monitoring Data ◽  
Quality Data ◽  
Urban Region ◽  
Country Level

AbstractSurface ozone (O3) and fine particulate matter (PM2.5) are dominant air pollutants in China. Concentrations of these pollutants can show significant differences between urban and nonurban areas. However, such contrast has never been explored on the country level. This study investigates the spatiotemporal characteristics of urban-to-suburban and urban-to-background difference for O3 (Δ[O3]) and PM2.5 (Δ[PM2.5]) concentrations in China using monitoring data from 1171 urban, 110 suburban, and 15 background sites built by the China National Environmental Monitoring Center (CNEMC). On the annual mean basis, the urban-to-suburban Δ[O3] is −3.7 ppbv in Beijing-Tianjin-Hebei, 1.0 ppbv in the Yangtze River Delta, −3.5 ppbv in the Pearl River Delta, and −3.8 ppbv in the Sichuan Basin. On the contrary, the urban-to-suburban Δ[PM2.5] is 15.8, −0.3, 3.5 and 2.4 µg m−3 in those areas, respectively. The urban-to-suburban contrast is more significant in winter for both Δ[O3] and Δ[PM2.5]. In eastern China, urban-to-background differences are also moderate during summer, with −5.1 to 6.8 ppbv for Δ[O3] and −0.1 to 22.5 µg m−3 for Δ[PM2.5]. However, such contrasts are much larger in winter, with −22.2 to 5.5 ppbv for Δ[O3] and 3.1 to 82.3 µg m−3 for Δ[PM2.5]. Since the urban region accounts for only 2% of the whole country’s area, the urban-dominant air quality data from the CNEMC network may overestimate winter [PM2.5] but underestimate winter [O3] over the vast domain of China. The study suggests that the CNEMC monitoring data should be used with caution for evaluating chemical models and assessing ecosystem health, which require more data outside urban areas.

scholarly journals NO<sub>x</sub> emissions in China: historical trends and future perspectives

2013 ◽  
Vol 13 (6) ◽  
pp. 16047-16112 ◽  
Author(s):  
B. Zhao ◽  
S. X. Wang ◽  
J. Y. Xu ◽  
K. Fu ◽  
Z. Klimont ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Emission Reduction ◽  
Power Plants ◽  
Ambient Air ◽  
Control Measures ◽  
Nox Emission ◽  
Nox Emissions ◽  
Emission Scenarios ◽  
Emission Reductions ◽  
Stringent Control

Abstract. Nitrogen oxides (NOx) are key pollutants for the improvement of ambient air quality. Within this study we estimated the historical NOx emissions in China for the period 1995–2010, and calculated future NOx emissions every five years until 2030 under six emission scenarios. Driven by the fast growth of energy consumption, we estimate the NOx emissions in China increased rapidly from 11.0 Mt in 1995 to 26.1 Mt in 2010. Power plants, industry and transportation were major sources of NOx emissions, accounting for 28.4, 34.0, and 25.4% of the total NOx emissions in 2010, respectively. Two energy scenarios, a business as usual scenario (BAU) and an alternative policy scenario (PC), were developed to project future energy consumption. In 2030, total energy consumption is projected to increase by 64 and 27% from 2010 level respectively. Three sets of end-of-pipe pollution control measures, including baseline, progressive, and stringent control case, were developed for each energy scenario, thereby constituting six emission scenarios. By 2030, the total NOx emissions are projected to increase (compared to 2010) by 36% in the baseline while policy cases result in reduction up to 61% in the most ambitious case with stringent control measures. More than a third of the reduction achieved by 2030 between least and most ambitious scenario comes from power sector and more than half is distributed equally between industry and transportation sectors. Selective Catalytic Reduction dominates the NOx emission reductions in power plants, while life style changes, control measures for industrial boilers and cement production are major contributors to reductions in industry. Timely enforcement of legislation on heavy duty vehicles would contribute significantly to NOx emission reductions. About 30% of the NOx emission reduction in 2020, and 40% of the NOx emission reduction in 2030 could be treated as the ancillary benefit of energy conservation. Sensitivity analysis was conducted to explore the impact of key factors on future emissions.

Weekly cycle of NOx emissions as laboratory of atmospheric chemistry

2021 ◽  
Author(s):  
Steffen Beirle ◽  
Steffen Dörner ◽  
Vinod Kumar ◽  
Thomas Wagner
Keyword(s):  
Atmospheric Chemistry ◽  
Emission Reduction ◽  
Power Plants ◽  
Nox Emissions ◽  
Satellite Measurements ◽  
Weekly Cycle ◽  
Christian Culture ◽  
Tropospheric No2 ◽  
Reduction Of Nox ◽  
The Mean

&lt;p&gt;Satellite observations provide unique information on the amount and spatial distribution of tropospheric NO2. Several studies use such datasets for deriving NOx emissions. However, due to nonlinearities in the NOx chemistry (i.e., the dependency of the OH concentration and thus the NO2 lifetime on the NO2 concentration), the observed column densities of NO2 are not directly proportional to the underlying NOx emissions. Consequently, a certain reduction in NOx emissions could result in disproportionate reduction of the corresponding NO2 columns, which could be stronger or weaker depending on the chemical state (O3, NOx and VOC levels) and conditions like temperature, humidity and acitinic flux. This effect complicates the quantification of NOx emissions from satellite measurements of NO2, and e.g. biases the emission reduction as derived from the reduction of NO2 column densities observed during recent lockdowns. &amp;#160;&lt;/p&gt;&lt;p&gt;Here we quantify the nonlinearity of the NOx system for different cities as well as power plants by investigating the effect of reduced NOx emissions on days of rest, i.e. Fridays/Sundays in Muslim/Christian culture, respectively. The reduction of NOx emissions is thereby quantified based on the continuity equation by calculating the divergence of the mean NO2 flux. This method has been proven to be sensitive for localized sources, where the uncertainties due to NO2 lifetime are small (Beirle et al., Sci. Adv., 2019). This reduction in emissions is then set in relation to the corresponding reduction of NO2 columns integrated around the source, which strongly depend on the NO2 lifetime.&lt;/p&gt;

scholarly journals Non-linear response of PM<sub>2.5</sub> to changes in NO<sub><i>x</i></sub> and NH<sub>3</sub> emissions in the Po basin (Italy): consequences for air quality plans

2021 ◽  
Vol 21 (12) ◽  
pp. 9309-9327
Author(s):  
Philippe Thunis ◽  
Alain Clappier ◽  
Matthias Beekmann ◽  
Jean Philippe Putaud ◽  
Cornelis Cuvelier ◽  
...  
Keyword(s):  
Air Quality ◽  
Emission Reduction ◽  
Fine Particulate Matter ◽  
Oxidative Capacity ◽  
Nox Emission ◽  
Linear Processes ◽  
Emission Reductions ◽  
Nh3 Emission ◽  
Non Linear ◽  
Pm2.5 Concentration

Abstract. Air pollution is one of the main causes of damages to human health in Europe, with an estimate of about 380 000 premature deaths per year in the EU28, as the result of exposure to fine particulate matter (PM2.5) only. In this work, we focus on one specific region in Europe, the Po basin, a region where chemical regimes are the most complex, showing important non-linear processes, especially those related to interactions between NOx and NH3. We analyse the sensitivity of PM2.5 concentration to NOx and NH3 emissions by means of a set of EMEP model simulations performed with different levels of emission reductions, from 25 % up to a total switch-off of those emissions. Both single and combined precursor reduction scenarios are applied to determine the most efficient emission reduction strategies and quantify the interactions between NOx and NH3 emission reductions. The results confirmed the peculiarity of secondary PM2.5 formation in the Po basin, characterised by contrasting chemical regimes within distances of a few (hundred) kilometres, as well as non-linear responses to emission reductions during wintertime. One of the striking results is the slight increase in the PM2.5 concentration levels when NOx emission reductions are applied in NOx-rich areas, such as the surroundings of Bergamo. The increased oxidative capacity of the atmosphere is the cause of the increase in PM2.5 induced by a reduction in NOx emission. This process could have contributed to the absence of a significant PM2.5 concentration decrease during the COVID-19 lockdowns in many European cities. It is important to account for this process when designing air quality plans, since it could well lead to transitionary increases in PM2.5 at some locations in winter as NOx emission reduction measures are gradually implemented. While PM2.5 chemical regimes, determined by the relative importance of the NOx vs. NH3 responses to emission reductions, show large variations seasonally and spatially, they are not very sensitive to moderate (up to 50 %–60 %) emission reductions. Beyond 25 % emission reduction strength, responses of PM2.5 concentrations to NOx emission reductions become non-linear in certain areas of the Po basin mainly during wintertime.

scholarly journals A comparison study between CMAQ-simulated and OMI-retrieved NO<sub>2</sub> columns over East Asia for evaluation of NO<sub>x</sub> emission fluxes of INTEX-B, CAPSS, and REAS inventories

2015 ◽  
Vol 15 (4) ◽  
pp. 1913-1938 ◽  
Author(s):  
K. M. Han ◽  
S. Lee ◽  
L. S. Chang ◽  
C. H. Song
Keyword(s):  
East Asia ◽  
Eastern China ◽  
Influential Factors ◽  
Nox Emission ◽  
Nox Emissions ◽  
Air Quality Model ◽  
Ozone Monitoring Instrument ◽  
Model Simulations ◽  
Tropospheric No2 ◽  
Emission Fluxes

Abstract. Comparison between the CMAQ (Community Multi-scale Air Quality Model)-calculated and OMI (Ozone Monitoring Instrument)-retrieved tropospheric NO2 columns was carried out for 2006 over East Asia (100–150° E; 20–50° N) to evaluate the bottom-up NOx emission fluxes of INTEX-B, CAPSS, and REAS v1.11 inventories. The three emission inventories were applied to the CMAQ model simulations for the countries of China, South Korea, and Japan, respectively. For the direct comparison between the two NO2 columns, the averaging kernels (AKs) obtained from the Royal Netherlands Meteorological Institute (KNMI)/DOMINO v2.0 daily product were applied to the CMAQ-simulated data. The analysis showed that the two tropospheric NO2 columns from the CMAQ model simulations and OMI observations (ΩCMAQ,AK and ΩOMI) had good spatial and seasonal correlation, with correlation coefficients ranging from 0.71 to 0.96. In addition, the normalized mean errors (NMEs) between the ΩCMAQ,AK and ΩOMI were found to range from ~ 40 to ~ 63%. The ΩCMAQ,AK were, on annual average, ~ 28% smaller (in terms of the NMEs) than the ΩOMI, indicating that the NOx emissions used were possibly underestimated in East Asia. Large absolute differences between the ΩCMAQ,AK and ΩOMI were found, particularly over central eastern China (CEC) during winter (annual averaged mean error of ~ 4.51 × 1015 molecules cm−2). Although such differences between the ΩCMAQ,AK and ΩOMI are likely caused by the errors and biases in the NOx emissions used in the CMAQ model simulations, it can be rather difficult to quantitatively relate the differences to the accuracy of the NOx emissions, because there are also several uncertain factors in the CMAQ model, satellite-retrieved NO2 columns and AK products, and NOx and other trace gas emissions. In this context, three uncertain factors were selected and analyzed with sensitivity runs (monthly variations in NOx emissions; influences of different NOx emission fluxes; and reaction probability of N2O5 radicals). Other uncertain or possible influential factors were also discussed to suggest future direction of the study.

Low NOx Emission Technology for the Vx4.3A Gas Turbine Series in Fuel Oil Operation

2002 ◽  
Author(s):  
Juergen Meisl ◽  
Gerald Lauer ◽  
Stefan Hoffmann
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Nox Emission ◽  
Fuel Oil ◽  
Liquid Fuels ◽  
Nox Emissions ◽  
Premix Combustion ◽  
Reduction Of Nox ◽  
Low Nox Emission ◽  
Distillate Fuel

This contribution describes the systematic refinement of the hybrid burner used in Siemens Vx4.3A gas turbines for lean premix combustion of various liquid fuels such as Distillate fuel No. 2, Naphtha and Condensate. Additionally to the dry premix operation fuel/water emulsions are used in premix mode for a further reduction of NOx emissions or power augmentation. NOx emissions of less than 72 ppm are already achieved with the HR3 hybrid burner in dry premix mode. These can be reduced to values below of 42 ppm NOx in emulsion mode.

scholarly journals NOx emissions in China: historical trends and future perspectives

2013 ◽  
Vol 13 (19) ◽  
pp. 9869-9897 ◽  
Author(s):  
B. Zhao ◽  
S. X. Wang ◽  
H. Liu ◽  
J. Y. Xu ◽  
K. Fu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Emission Reduction ◽  
Power Plants ◽  
Ambient Air ◽  
Control Measures ◽  
Nox Emission ◽  
Nox Emissions ◽  
Emission Scenarios ◽  
Emission Reductions ◽  
Stringent Control

Abstract. Nitrogen oxides (NOx) are key pollutants for the improvement of ambient air quality. Within this study we estimated the historical NOx emissions in China for the period 1995–2010, and calculated future NOx emissions every five years until 2030 under six emission scenarios. Driven by the fast growth of energy consumption, we estimate the NOx emissions in China increased rapidly from 11.0 Mt in 1995 to 26.1 Mt in 2010. Power plants, industry and transportation were major sources of NOx emissions, accounting for 28.4%, 34.0%, and 25.4% of the total NOx emissions in 2010, respectively. Two energy scenarios, a business as usual scenario (BAU) and an alternative policy scenario (PC), were developed to project future energy consumption. In 2030, total energy consumption is projected to increase by 64% and 27% from 2010 level respectively. Three sets of end-of-pipe pollution control measures, including baseline, progressive, and stringent control case, were developed for each energy scenario, thereby constituting six emission scenarios. By 2030, the total NOx emissions are projected to increase (compared to 2010) by 36% in the baseline while policy cases result in reduction up to 61% in the most ambitious case with stringent control measures. More than a third of the reduction achieved by 2030 between least and most ambitious scenario comes from power sector, and more than half is distributed equally between industry and transportation sectors. Selective catalytic reduction dominates the NOx emission reductions in power plants, while life style changes, control measures for industrial boilers and cement production are major contributors to reductions in industry. Timely enforcement of legislation on heavy-duty vehicles would contribute significantly to NOx emission reductions. About 30% of the NOx emission reduction in 2020 and 40% of the NOx emission reduction in 2030 could be treated as the ancillary benefit of energy conservation. Sensitivity analysis was conducted to explore the impact of key factors on future emissions.

Burning Methanol and its Blends Attractive Alternative for Emission Reduction

2016 ◽  
Author(s):  
B. Chudnovsky ◽  
D. Livshits ◽  
S. Baitel
Keyword(s):  
Emission Reduction ◽  
Liquid Fuel ◽  
Turbulent Energy ◽  
Diesel Oil ◽  
Fuel Oil ◽  
Nox Emissions ◽  
So2 Emissions ◽  
Heavy Fuel Oil ◽  
Reduction Of Nox ◽  
Reduction Of Emissions

Traditional methods for reducing emissions, by modification of the firing system to control the mixing of fuel and air, the reduction of flame temperatures (for NOx emission reduction), and/or the post combustion treatment of the flue gas to remove NOx, SO2 particulates are very expensive. Hence, before implementation of expensive measures for the reduction of emissions, it is necessary to evaluate all low cost alternatives, such as burning alternative fuels and mixing it with other liquid fuels. Methanol offers these advantages, being a derivative of natural gas which is partly de-linked from oil, and is a clean burning fuel. Existing experience [1, 2] has shown that with inexpensive and minimal system modifications, methanol is easily fired and is fully feasible as an alternative fuel. Relative to heavy fuel and light fuel, methanol can achieve improved efficiency and lower NOx emissions due to the lower flame temperature and nitrogen content. Since methanol contains no sulfur, there are no SO2 emissions. The clean burning characteristics of methanol are expected to lead to clean pressure parts and lower maintenance costs. In this paper we present results for the specific 10 ton/hr industrial boiler (results of the burning of methanol in large utility boilers we presented in our earlier publications) located at DOR Chemicals. In this study we experimented with methanol fractions (from 0 to 100 % by heat) at different boiler loads and found that the methanol and heavy fuel oil mixtures enabled us to meet the commonly accepted emissions limit for NOx with zero CO emissions. SO2 emissions were also reduced according to methanol heat fraction. Methanol burning leads to a more than 10 % reduction of CO2. It should be noted that in our tests we used a special patented mixing device (the “Fuel Activation Device – FAD) developed by Turbulent Energy Inc. for preparing premixed or in-line blends. The results show that more than 50% of NOx reduction is achieved when light fuel oil is replaced by methanol and more than an 80% reduction when heavy fuel oil is replaced by methanol. For all boiler operation modes 100% of combustion efficiency is achieved. Methanol and liquid fuel blends lead to significant reduction of emissions depending on the methanol heat fraction. Burning of a blend of liquid fuel with water leads to a significant reduction of NOx. In addition, the usage of the FAD in our tests had positive effects on boiler efficiency improvement both for LFO and methanol firing. In this paper we also present the study of methanol and diesel fuel burning in diesel engine. It should be noted that blends were prepared by a using special mixing device developed by Turbulent Energy Inc. The performance of the engine using blended fuel compared to the performance of the engine with diesel fuel. It was also found that with using the blend one may achieve a more than 75 % reduction of NOx emissions when diesel oil is replaced by 20% methanol. Methanol and diesel oil co-firing leads to a reduction of SO2 emissions depending on the heat fraction of methanol. We believe that the conclusions of the work presented are general and can be applied to any other industrial, utility boiler, or diesel engine as well.

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