Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

Gas components, like carbon monoxide (CO) and dioxide (CO2), can be measured on a wet- or dry-basis depending on whether the water is left or removed from the sample before analysis. The dry concentrations of gaseous components in the exhaust from internal combustion engines are converted to wet concentrations with conversion factors based on the combustion products and the fuel properties. Recent CO2 measurements with portable emissions measurement systems (PEMS) compared to laboratory grade equipment showed differences during the first minutes after engine start. In this study we compared instruments measuring on a dry- and wet-basis using different measuring principles (non-dispersive infrared detection (NDIR) and Fourier-transform infrared spectroscopy (FTIR)) at the exhaust of gasoline, compressed natural gas (CNG), and diesel light-duty and L-category vehicles. The results showed an underestimation of the CO2 and CO mass emissions up to 13% at cold start when the conversion factor is applied and not direct “wet” measurements are taken, raising concerns about reported CO2 and CO cold start emissions in some cases. The underestimation was negligible (<1%) for CO2 when the whole test (20–30 min) was considered, but not for CO (1%–10% underestimation) because the majority of emissions takes place at cold start. Exhaust gas temperature, H2O measurements and different expressions of the dry-wet corrections confirmed that the differences are due to condensation at the exhaust pipes and aftertreatment devices when the surface temperatures are lower than the dew point of the exhaust gases. The results of this study help to interpret differences when comparing instruments with different principles of operation at the same location, instruments sampling at different locations, or the same instrument measuring different driving test cycles or at different ambient temperatures (e.g., −7 °C)

Quantification of organic P and low-molecular-weight organic acids in ferralsol soil extracts by ion chromatography

A better understanding of the composition of organic phosphorus (organic P) and low-molecular-weight organic acids (LMWOAs) in soil will make it possible to predict phosphorus cycling, improve biomass production and help phosphorus management in forest plantations. The method for quantifying organic P and LMWOAs in soil extracts was developed using ion chromatography (IC). Sodium hydroxide (0.5 N) was validated as an extractant for both organic P and LMWOAs. A mixture of 200 mM NaOH and ultrapure water was used to create a linear gradient elution. The eluent program separated five different organic P forms (glucose-6-phosphate, AMP, fructose-1,6-bisphosphate, ATP and phytate) as well as pyrophosphate from inorganic P (Pi), and four LMWOAs (malate, malonate, oxalate and citrate) in a 25 minute run through an AS11 column. The variability of the quantification was expressed as the relative standard deviation which was less than 20% for most of the analytes. The recovery rate of organic P assayed by IC to colorimetry was 110 +/- 20%. This chromatographic method was shown to be suitable for the quantification of organic P and LMWOAs in soil samples and could be an easier alternative to P-31 Nuclear Magnetic Resonance (NMR) measurement

Particle number measurements in the European legislation and future JRC activities

The solid particle number method was introduced in the European Union (EU) light-duty legislation for diesel vehicles to ensure the installation of the best-available technology for particles (i.e., wall-flow diesel particulate filters) without the uncertainties of the volatile nucleation mode and without the need of large investment for purchasing the equipment. Later it was extended to gasoline vehicles with direct injection engines, heavy-duty engines (both compression ignition and positive ignitions) and non-road mobile machinery engines. Real Driving Emissions (RDE) testing on the road with Portable Emissions Measurement Systems (PEMS) for particle number (and NOx) during type approval and in-service conformity testing was recently (in 2017) introduced for light-duty vehicles, and is under discussion for heavy-duty vehicles in-service conformity testing. This paper will summarize the existing legislation regarding solid particle number and discuss the on-going activities at EU level. The main focus at the moment is on improving the calibration procedures, and extending the lower detection size below 23 nm with interlaboratory exercises. In parallel, discussions are on-going to introduce testing at low ambient temperature, regeneration emissions in the light-duty regulation, a particle limit for other technologies such as gasoline port-fuel injection vehicles, and the feasibility of particle measurements to L-category vehicles (mopeds, motorcycles, tricycles and minicars). A short overview of periodical technical inspection investigations and the situation regarding non-exhaust traffic related sources with special focus on brakes and tyres will be described

Expression of E-cadherin and alpha-, beta-, gamma-catenins in patients with bladder cancer: identification of gamma-catenin as a new prognostic marker of neoplastic progression in T1 superficial urothelial tumors.

International audienceLoss of intercellular adhesion facilitates tumor invasion. To clarify the relation between altered expression of cell adhesion molecules and progression of T1 superficial bladder tumors, 101 cases (71 T1 tumors, 30 T2/T3 tumors) were examined immunohistochemically for E-cadherin and alpha-, beta-, and gamma-catenins. A highly significant correlation was observed between the decreased expression of all molecules and increased TNM stage (P < .001). Univariate analysis, performed in cases of T1 tumors, revealed association of abnormal E-cadherin with beta-catenin diminution. Survival curves were established with the Kaplan-Meier method and analyzed according to clinical and histopathologic parameters using the log-rank test. Cox multivariate analysis revealed only gamma-catenin as an independent predictor of progression-free survival in patients with stage T1 bladder urothelial tumors. The characterization of T1 tumors that will progress could lead to the identification of patients who might benefit from surgery to avoid vesical muscle invasion and, consequently, metastasis

Improvement in spectral library-based quantification of soil properties using representative spiking and local calibration – The case of soil inorganic carbon prediction by mid-infrared spectroscopy

International audienceMid-infrared reflectance spectroscopy (MIRS) is time- and cost-effective. It was used for quantifying soil inorganic carbon (SIC) concentration in France based on a national library, and performances were evaluated on an independent regional set. Our objective was to improve the accuracy of MIRS predictions based on common multivariate regression, through spiking (enrichment of the national library with some representative target samples) with possible extra-weighting (replication of spiking samples) and local calibration (only using calibration samples that are spectral neighbours of each target samples), which have not been fully explored yet, in combination especially.Global (i.e. common) calibration yielded accurate prediction (standard error of prediction, SEP, was ≈ 5 g kg−1), which could be improved when the library was completed with spiking samples (optimally 10 samples extra-weighted 40 times; SEP = 3.3 g kg−1). Using spiking samples only (without the library) yielded slightly less accurate results (SEP = 3.6 g kg−1). Prediction was more accurate using local calibration without spiking, but on a validation set that was reduced because some validation samples lacked calibration neighbours (SEP = 2.5–2.7 g kg−1). Local calibration with spiking (optimally 10 samples without extra-weight) yielded somewhat less accurate prediction but for the full validation set when few calibration neighbours were required (SEP = 2.7 g kg−1), or higher accuracy on the reduced validation set when many neighbours were required (SEP = 2.3 g kg−1).These accurate predictions demonstrated the usefulness of representative spiking and local calibration for rendering large soil spectral libraries fully operational, while extra-weighting had no additional benefit. Along with more exhaustive spectral libraries, this paves the way for extensive use of MIRS for SIC determination

Real-time analysis of aromatics in combustion engine exhaust by Resonance-Enhanced Multiphoton Ionisation Time-Of-Flight Mass Spectrometry (REMPI-TOF-MS): A robust tool for chassis dynamometer testing.

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes&#39; photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated

Chemical analysis and ozone formation potential of exhaust from dual-fuel (liquefied petroleum gas/gasoline) light duty vehicles.

Measures must be undertaken to lower the transport sector&#39;s contribution to anthropogenic emissions. Vehicles powered by liquefied petroleum gas (LPG) are an option due to their reduced emissions of air pollutants compared to engines with conventional fuels. In the present study, ten different dual-fuel LPG/gasoline light duty vehicles were tested, which all complied with European emission level legislation EURO-4. Tests with LPG and gasoline were performed on a chassis dynamometer by applying the New European Driving Cycle (NEDC) and emission factors and ozone formation potentials of both kinds of fuels were compared. The components investigated comprised regulated compounds. CO(2), volatile hydrocarbons and carbonyls. On-line analysis of aromatic species was carried out by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). We demonstrate that utilization of LPG can entail some environmental benefits by reducing emissions. However, for dual-fuel LPG/gasoline vehicles running on LPG the benefits are less than expected. The main reason is that dual-fuel vehicles usually start the engine up on gasoline even when LPG is selected as fuel. This cold-start phase is crucial for the quality of the emissions. Moreover, we demonstrate an influence on the chemical composition of emissions of vehicle performance, fuel and the evaporative emission system of the vehicles