Chemical characterization of organic particulate matter from on-road traffic in Sao Paulo, Brazil

This study reports emission of organic particulate matter by light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) in the city of São Paulo, Brazil, where vehicles run on three different fuel types: gasoline with 25 % ethanol (called gasohol, E25), hydrated ethanol (E100), and diesel (with 5 % biodiesel). The experiments were performed at two tunnels: Jânio Quadros (TJQ), where 99 % of the vehicles are LDVs, and RodoAnel Mário Covas (TRA), where up to 30 % of the fleet are HDVs. Fine particulate matter (PM2.5) samples were collected on quartz filters in May and July 2011 at TJQ and TRA, respectively. The samples were analyzed by thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) and by thermal–optical transmittance (TOT). Emission factors (EFs) for organic aerosol (OA) and organic carbon (OC) were calculated for the HDV and the LDV fleet. We found that HDVs emitted more PM2.5 than LDVs, with OC EFs of 108 and 523 mg kg−1 burned fuel for LDVs and HDVs, respectively. More than 700 ions were identified by TD-PTR-MS and the EF profiles obtained from HDVs and LDVs exhibited distinct features. Unique organic tracers for gasoline, biodiesel, and tire wear have been tentatively identified. nitrogen-containing compounds contributed around 20 % to the EF values for both types of vehicles, possibly associated with incomplete fuel burning or fast secondary production. Additionally, 70 and 65 % of the emitted mass (i.e. the OA) originates from oxygenated compounds from LDVs and HDVs, respectively. This may be a consequence of the high oxygen content of the fuel. On the other hand, additional oxygenation may occur during fuel combustion. The high fractions of nitrogen- and oxygen-containing compounds show that chemical processing close to the engine / tailpipe region is an important factor influencing primary OA emission. The thermal-desorption analysis showed that HDVs emitted compounds with higher volatility, and with mainly oxygenated and longer chain hydrocarbons than LDVs

What chemical species are responsible for new particle formation and growth in the Netherlands? A hybrid positive matrix factorization (PMF) analysis using aerosol composition (ACSM) and size (SMPS)

Aerosol formation acts as a sink for gas-phase atmospheric species that controls their atmospheric lifetime and environmental effects. To investigate aerosol formation and evolution in the Netherlands, a hybrid positive matrix factorization (PMF) analysis was conducted using observations from May, June, and September 2021 collected in the rural site of Cabauw in the central part of the Netherlands. The hybrid input matrix consists of the full organic mass spectrum acquired from a time-of-flight aerosol chemical speciation monitor (ToF-ACSM), ACSM inorganic species concentrations, and binned particle size distribution concentrations from a scanning mobility particle sizer (SMPS). These hybrid PMF analyses discerned four factors that describe aerosol composition variations: two size-driven factors that are related to new particle formation (NPF) and growth (F4 and F3), as well as two bulk factors driven by composition, not size (F2 and F1). The distribution of chemical species across these factors shows that different compounds are responsible for nucleation and growth of new particles. The smallest-diameter size factor (F4) contains ammonium sulfate and organics and typically peaks during the daytime. Newly formed particles, represented by F4, are mainly correlated with wind from the southwesterly-westerly and easterly sectors that transport sulfur oxides (SOx), ammonia (NH3), and organic precursors to Cabauw. As the particles grow from F4 to F3 and to bulk factors, nitrate and organics play an increasing role, and the particle loading diurnal cycle shifts from daytime to a nighttime maximum. Greater organics availability makes secondary organic aerosol (SOA) more influential in summertime aerosol growth, principally due to volatility differences produced by seasonal variation in photooxidation and temperature.</p

Methylsiloxanes from Vehicle Emissions Detected in Aerosol Particles

Methylsiloxanes have gained growing attention as emerging pollutants due to their toxicity to organisms. As man-made chemicals with no natural source, most research to date has focused on volatile methylsiloxanes from personal care or household products and industrial processes. Here, we show that methylsiloxanes can be found in primary aerosol particles emitted by vehicles based on aerosol samples collected in two tunnels in São Paulo, Brazil. The aerosol samples were analyzed with thermal desorption-proton transfer reaction-mass spectrometry (TD-PTR-MS), and methylsiloxanes were identified and quantified in the mass spectra based on the natural abundance of silicon isotopes. Various methylsiloxanes and derivatives were found in aerosol particles from both tunnels. The concentrations of methylsiloxanes and derivatives ranged 37.7–377 ng m–3, and the relative fractions in organic aerosols were 0.78–1.9%. The concentrations of methylsiloxanes exhibited a significant correlation with both unburned lubricating oils and organic aerosol mass. The emission factors of methylsiloxanes averaged 1.16 ± 0.59 mg kg–1 of burned fuel for light-duty vehicles and 1.53 ± 0.37 mg kg–1 for heavy-duty vehicles. Global annual emissions of methylsiloxanes in vehicle-emitted aerosols were estimated to range from 0.0035 to 0.0060 Tg, underscoring the significant yet largely unknown potential for health and climate impacts

Einfluss von Ozon, CO2 und Trockenstress auf das Wachstum und die Pollenproduktion der Beifuß-Ambrosie (Ambrosia artemisiifolia)

Klimaveränderungen beeinflussen das pflanzliche Wachstum und können auch einen Einfluss auf den Pollen haben. Wichtige Faktoren sind dabei erhöhte CO2-Konzentrationen, Trockenstress und Schadstoffbelastungen. Die Pollen der Beifuß-Ambrosie gehören mit zu den stärksten Allergie-Auslösern und beeinflussen die menschliche Gesundheit. In dieser Studie wurde die Beifuß-Ambrosie über die gesamte Vegetationsperiode erhöhten CO2- (700 ppm) und Ozon- (80 ppb) Konzentrationen ausgesetzt. Ferner wurde der Einfluss von Trockenstress unter unterschiedlichen CO2-Konzentrationen untersucht. Erhöhtes CO2 und Trockenstress hatten keinen Einfluss auf die Größe, Form und Oberflächenstruktur des Pollens. Bezüglich morphologischer Parameter resultierte erhöhtes CO2 in einer Zunahme des Stängelwachstums und der Hauptinfloreszenz, sowie vermehrter Pollenproduktion. Trockenstress führte zu einem reduzierten Wachstum des Stängels und der Hauptinfloreszenz und verringerter Pollen-Ausbeute. Erhöhte Ozon-Werte führten tendenziell zu einer geringeren, statistisch jedoch nicht signifikant veränderten Pollenausbeute. Diese Ergebnisse weisen darauf hin, dass Klimaveränderungen die Entwicklung von Ambrosia-Pollen beeinflussen und dadurch auch die öffentliche Gesundheit beeinträchtigen.Stichwörter: Allergie, Infloreszenz, Klimawandel, Luftschadstoff, Stängel, VegetationsperiodeEffects of ozone, CO2 and drought stress on the growth and pollen production of common ragweed (Ambrosia artemisiifolia)Climate change will affect the growth of plants and may also influence the production of pollen. The important factors influencing climate change are increased CO2 concentrations, drought and air pollution. Common ragweed pollen is known to be strongly allergenic, thereby affecting human health. In this study, common ragweed plants were grown over an entire vegetation period under conditions of twice the ambient level of CO2 (700 ppm) and ozone (80 ppm), respectively. Furthermore, the effect of soil drought combined with different CO2 levels was investigated. Scanning electron microscopy showed no change in surface morphology and size of CO2- and drought-treated pollen. Regarding morphological parameters, elevated CO2 resulted in an increased length of the stem and the main inflorescence and higher pollen yields, whereas drought reduced the stem and inflorescence lengths and resulted in a lower pollen yield, a result that was mitigated by elevated CO2. Twice the ambient level of ozone tends to result in a reduced pollen yield. However, this was not statistically significant. These findings support the idea that the conditions of climate change will influence the development of common ragweed pollen, thereby affecting public health.Keywords: Allergy, air pollution, inflorescence, climate change, stem, vegetation perio

CAR T Cells in Trials: Recent Achievements and Challenges that Remain in the Production of Modified T Cells for Clinical Applications

The adoptive transfer of chimeric antigen receptor (CAR)-modified T cells is attracting growing interest for the treatment of malignant diseases. Early trials with anti-CD19 CAR T cells have achieved spectacular remissions in B-cell leukemia and lymphoma, so far refractory, very recently resulting in the Food and Drug Administration approval of CD19 CAR T cells for therapy. With further applications and increasing numbers of patients, the reproducible manufacture of high-quality clinical-grade CAR T cells is becoming an ever greater challenge. New processing techniques, quality-control mechanisms, and logistic developments are required to meet both medical needs and regulatory restrictions. This paper summarizes the state-of-the-art in manufacturing CAR T cells and the current challenges that need to be overcome to implement this type of cell therapy in the treatment of a variety of malignant diseases and in a greater number of patients

Additive manufactured AlSi10Mg samples using Selective Laser Melting (SLM): Microstructure, high cycle fatigue, and fracture behavior

In order to produce serial parts via additive layer manufacturing, the fatigue performance can be a critical attribute. In this paper, the microstructure, high cycle fatigue (HCF), and fracture behavior of additive manufactured AlSi10Mg samples are investigated. The samples were manufactured by a particular powder-bed process called Selective Laser Melting (SLM) and machined afterwards. 91 samples were manufactured without (30°C) and with heating (300°C) of the building platform and in different directions (0°, 45°, 90°). Samples were tested in the peak-hardened (T6) and as-built condition. The Wöhler curves were interpolated by a Weibull distribution. The results were analysed statistically by design of experiments, correlation analysis, and marginal means plots. The investigations show that the post heat treatment has the most considerable effect and the building direction has the least considerable effect on the fatigue resistance. The fatigue resistance of the sampl es, however, is high in comparison to the standard DIN EN 1706. The combination of 300°C platform heating and peak-hardening is a valuable approach to increase the fatigue resistance and neutralize the differences in fatigue life for the 0°, 45°, and 90° directions