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Fall M.,University of Rouen | Fall M.,Cheikh Anta Diop University | Haddouk H.,Center International Of Toxicologie | Loriot S.,University of Rouen | And 4 more authors.
Toxicological and Environmental Chemistry | Year: 2011

The aim of this study was to investigate the potential mutagenic activity of diesel engine exhaust in the Ames/Salmonella assay using a direct aerosol exposure system. So, TA 98 and TA 100 strains, with or without added S9 mix, were exposed to diesel emissions after varying degrees of filtration. Variants of these two strains, deficient in nitroreductase (TA 98NR and TA 100NR) or over-expressing O-Acetyl Transferase (YG 1024 and YG 1029), were also exposed to total (unfiltered) diesel exhaust to highlight the putative mutagenicity of any nitro-PAHs present in these emissions. Mutagenic activity of the diesel exhaust was demonstrated on Salmonella typhimurium, strains TA 100 and variants TA 100 NR and YG1029. The use of a particle filter did not modify the genotoxicity of the diesel emissions, indicating a major contribution of the gas phase to the mutagenicity of these diesel emissions. The prominent role of the particulate-associated nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) claimed by some authors working on diesel exhaust organic extracts was not confirmed by our results with native diesel exhaust exposure. Our results show that the gas phase is potentially more mutagenic than the particles alone. © 2011 Copyright Taylor and Francis Group, LLC. Source

Morin J.-P.,French Institute of Health and Medical Research | Preterre D.,Certam | Keravec V.,Certam | Monteil C.,University of Rouen | Dionnet F.,Certam
SAE International Journal of Engines | Year: 2011

One 4-stroke scooter and two 2-stroke scooters (50 cc bore) were run on dynamic test benches according to the EC47 driving cycle. Emissions from these scooters were continuously monitored, sampled and hot- diluted prior being driven to continuous flow through chambers containing organotypic cultures of lung tissue under bi-phasic Air/liquid culture conditions for three hours. Lung tissue was evaluated for viability (ATP), anti-oxidant defenses (intracellular GSH, Catalase, superoxide-dismutases, glutathione-S-Transferase, glutathione peroxidase, glutathione-reductase activity levels) and inflammatory reaction through the measurement of TNFalpha secretion in the culture medium. 4-stroke engine emissions had a moderate impact on lung tissue viability but induced a marked GSH depletion concomitant of increased GPx activity. 2-strokes engine emissions had variable impacts according to after-treatment technology and lube oil quality. Lower oxidation catalysis and mineral lube oil were found to be the worse situation inducing a marked lung tissue viability loss and high intracellular glutathione depletion, a marked decrease in SOD activity both Mn and Cu/Zn iso-enzymes being affected and a decrease in TNF alpha secretion. On the other hand, thigh oxidation catalysis and semi-synthetic lube oil was found to be the best situation with only minor tissue viability loss, moderate glutathione depletion, moderate elevation of glutathione peroxidase, almost no impact on superoxide dismutase activities and a moderate increase in TNFalpha secretion. The measurement of regulated emissions (CO, NO, NO2, HC, and particulate matter showed that under warm engine conditions, 2-stroke engine with high oxidation catalysis and semi-synthetic lube oil was the least emitting situation especially when CO, HC and particulate matter are considered. 4-stroke engine proved to have intermediate emissions levels especially for CO, HC and particulate matter. 2-stroke engine with low oxidation catalysis and mineral oil was found to be the worse situation especially for HC and particulate matter. In conclusion: emissions from small scooters may have detrimental impacts on lung tissue which may be highly reduced by the use of an oxidation catalyst on the exhaust line and by using high quality grade oil like semi-synthetic oil compared to mineral oil. Suitable recently designed after-treatment strategies allow a very efficient reduction of 2-stroke engine emissions and toxic potential leading to an even lesser impact than for the 4stroke commercially available engine emissions. © 2011 SAE International. Source

Portet-Koltalo F.,CNRS Organic Chemistry, Bioorganic Chemistry: Reactivity and Analysis | Preterre D.,Certam | Dionnet F.,Certam
Journal of Chromatography A | Year: 2011

A new sampling method was developed to collect vapor-phase polycyclic aromatic compounds (PAHs) downstream of a diesel engine equipped with a diesel particulate filter (DPF). This configuration allowed us to collect separately the particulate phase, which was trapped inside the DPF, and the vapor phase, which was sampled downstream of the DPF. PAHs, which were not predominantly absorbed into the poor organic fraction of the diesel soot, but were rather physically sorbed on high energetic adsorption sites, should be extracted using very drastic extraction conditions Microwave-assisted extraction using solvent mixtures composed of pyridine and diethylamine were used to desorb particulate PAHs, and the total PAH amounts corresponded to a very low value, i.e., 8μgg-1 or 0.24μgkm-1, with a predominance of low weight PAHs. For collection of the vapor phase, gas bubbling in an aqueous medium was preferred to conventional methods, e.g., trapping on solid sorbents, for several reasons: aqueous trapping allowed us to use a solid phase enrichment process (SPE) that permitted PAH sampling at the sub-picogram levels. Consequently, low volume sampling was possible even if the sampling duration was very short (20min). Additionally, the amount of time saved for the analysis was considerable when coupling SPE to the analytical system (liquid chromatography with fluorimetric detection). Solvent consumption for the overall sampling and analytical processes was also drastically reduced. Experiments on a diesel engine showed that vapor phase samples collected downstream of the DPF contained all of the 15 target priority PAHs, even the heaviest ones. The total vapor-phase PAH amount was 6.88μgNm-3 or 10.02μgkm-1, which showed that the gaseous fraction contains more PAHs than the particulate fraction. Partitioning coefficients (Kp) were estimated showing the predominance in the vapor phase of all the PAHs. However, the DPF technology effects a considerable decrease in the total PAH emission when compared to non-equipped diesel vehicles. © 2011 Elsevier B.V. Source

Salaun E.,CNRS Complex Interprofessional Research in Aerothermochemistry | Apeloig J.,CNRS Complex Interprofessional Research in Aerothermochemistry | Grisch F.,CNRS Complex Interprofessional Research in Aerothermochemistry | Yvonnet C.-E.,Certam | And 2 more authors.
SAE Technical Papers | Year: 2016

Dual-fuel engines are recognized as a short-medium term solution to reduce fuel consumption and pollutant emissions of CI engines, while maintaining high energy efficiency. Methane (CH4) was chosen as it offers the best compromise between its heating value and H/C ratio. The high auto-ignition temperature of CH4 requires auto-igniting a small quantity of liquid diesel before it initiates the combustion of the mixture. Therefore, new engine operations need to be specifically developed. This investigation explores the impact of time sequences of injection of the liquid fuel on the ignition of homogenous methane/air mixture. Experiments were performed on a Rapid Compression Expansion Machine (RCEM), to reproduce the operating and dynamic conditions encountered in a diesel engine cycle, allowing visualizations of fuel injection and combustion processes through a transparent piston. For the purpose of this work, the RCEM was modified to operate under dual-fuel conditions, while controlling the amount of diesel and methane-gas fueled. Experiments were performed for a wide range of equivalence ratios of the premixed charge. The study of the liquid fuel penetration and its consequence on igniting the homogenous charge was achieved using high-speed optical diagnostics. High-speed Schlieren technique (∼22 kHz) was applied to characterize the diesel spray penetration, as well as the in-cylinder liquid fuel distribution. High-speed shadowgraphy and OH∗-chemiluminescence techniques were used to determine ignitions delays. Moreover, the latest diagnostic was used to analyze the flame structure propagation and the heat release evolution. © Copyright 2016 SAE International. Source

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