Study of the PM Gas-Phase Filter Artifact Using a Setup for Mixing Diesel-Like Soot and Hydrocarbons

The filter artifact is a significant source of error in gravimetric measurements of particulate matter (PM) exhaust. However, only a few studies on the subject exist. Results from these studies show a large discrepancy mainly because the experiments were performed using real diesel vehicle exhaust with varying exhaust composition. In this study, a setup for mixing diesel-like soot and hydrocarbon vapor was constructed for generating a stable exhaust aerosol with adjustable composition. The particle size distribution of the diesel-fueled soot generator (GMD [geometric mean diameter] adjustable between 27 and 164 nm) was found to represent “real” exhaust particulate emission. This setup was applied for studying the filter artifact on Teflon-coated glass fiber filters using pentadecane as the hydrocarbon vapor. Experiments were performed using particle and hydrocarbon concentrations of 130–700 μg/m3 and 10–12 ppm, respectively. It was found that the particle concentration of the aerosol affects the filter artifact. At lower particle concentrations, more hydrocarbon adsorption was detected. In the absence of particles, the adsorption was highest. Furthermore, filter soot load, corresponding to 0.13%–0.66% of the clean filter mass, was found to affect adsorption. Sooty filters adsorbed less vapor than clean filters. However, increasing the soot load resulted in more adsorption. Moreover, it was found that the backup filter serves as a reasonable estimate of the filter artifact only for low particle concentrations and filter soot loads. These results indicate that the filter soot load is an important parameter influencing the filter artifact, and therefore, it should be considered when performing gravimetric sampling. The setup was proven to be a unique tool for quantitative studies of the filter artifact

#ScienceForUkraine: an Initiative to Support the Ukrainian Academic Community. “3 months since Russia’s invasion in Ukraine”, February 26 – May 31, 2022

here was an immediate ad-hoc response of the international scientific community to help scholars from universities affected by Russia's war in Ukraine. Official government-backed funding programmes later allowed the ad-hoc help offers to be sustainable and stable. The #ScienceForUkraine initiative is a grass-root initiative that emerged out of the desire to help; initially created as a central database for the worldwide offers for help. Its 133 active volunteers engaged with policy-makers and funding bodies to improve support to the Ukrainian academic community. The website scienceforukraine.eu became a central and well-known hub with a general database for help listings but also extensive curated link lists for further help. There were more than 120k visits in the past three months, 12k of which are reportedly from Ukraine. #ScienceForUkraine has many active country groups that flexibly respond to needs in their geographic area. Collecting information, creating posters for border stations, mentoring, consulting on how to organise transfers, and engaging with policy makers are some of the tasks performed by members. #ScienceForUkraine is active on all major social networks to be in touch with both the Western academic community (primarily Twitter and LinkedIn) and the Ukrainian academic community (mainly Facebook and Telegram); whereas students are reached mostly via Instagram. The initiative fulfils an important function by transmitting information from one sphere to the other. #ScienceForUkraine recorded well over 2,600 support listings (one listing may be directed at several scholars). 15% of these were offered by German institutions (410), followed by French (227) and Polish (183) institutions