Per and polyfluoroalkyl substances (PFAS), a class of toxic compounds often referred to as “forever chemicals”, are increasingly detected in the atmosphere. Aerosolisation from contaminated aqueous reservoirs has been proposed as a pathway for atmospheric PFAS, drawing analogy to sea-spray processes and supported by their elevated concentrations reported near sewage treatment facilities (Kizhakkethil et al., 2025). However, aerosolisation and particle formation in anthropogenically impacted waters differ fundamentally from marine systems, and the physico chemical controls governing PFAS aerosolisation outside the marine context remain poorly understood.The aim of this work was to investigate the effect of PFAS molecular properties, including carbon chain length and functional groups, on aerosolisation from contaminated aqueous solutions. Experiments were conducted in the Chamber for Aerosol Modelling and Bio-aerosol Research (ChAMBRe), Italy. Twenty five PFAS, covering short, medium and long chain perfluoroalkyl carboxylic acids, perfluoroalkane sulfonates, fluorotelomer sulfonates and emerging alternatives representative of wastewater impacted environments were investigated. The role of bioaerosol seed particles commonly present in such environments was also assessed, as they could act as sinks or carriers for highly surface active PFAS and thereby influence their aerosol phase distribution.Aerosol mass size distributions revealed a strong dependence on molecular structure, indicating compound-specific particle-phase behaviour. The presence of biological particles did not systematically alter PFAS size-resolved distributions, suggesting that the studied PFAS exhibited limited interaction with bioaerosols and remained predominantly in the submicron size range under the investigated conditions, which may favour their atmospheric persistence and long-range transport.Overall, these findings indicate that primary aerosol formation from contaminated aqueous systems represents a chemically selective pathway for introducing PFAS into the organic aerosol, with size-resolved characteristics governed primarily by molecular properties and aerosol formation processes.Reference: Kizhakkethil, J. P., Shi, Z., Bogush, A., and Kourtchev, I.: Measurement report: Per- and polyfluoroalkyl substances (PFAS) in particulate matter (PM10) from activated sludge aeration, Atmos. Chem. Phys., 25, 5947–5958, https://doi.org/10.5194/acp-25-5947-2025, 2025.

Fine particulate matter (PM2.5) is a major air pollutant in South Asian cities; however, information on its carbonaceous composition and multi-wavelength optical properties remains limited for Lahore, Pakistan. This study investigated PM2.5 collected at an urban site in Lahore between 15 March and 29 April 2025. A total of 30 filter samples were collected; owing to sample losses during transportation, 25 filters were available for gravimetric and optical analyses, while a subset of 15 filters, selected to cover the sampling period and a broad range of PM2.5 concentrations, was used for carbonaceous aerosol analysis. Aerosol light absorption was determined using the Multi-Wavelength Absorbance Analyzer (MWAA) at five wavelengths (375, 407, 532, 635, and 850 nm). PM2.5 concentrations ranged from 40 to 417 μg m⁻³, with an average of 137 ± 84 μg m⁻³, indicating severe particulate pollution throughout the sampling period. Organic carbon was the dominant carbonaceous component, contributing 76.6% of total carbon, whereas elemental carbon accounted for 23.4%. The MWAA measurements showed the expected decrease in aerosol absorption with increasing wavelength, reflecting the spectral behaviour of carbonaceous aerosols. The average Absorption Ångström Exponent (AAE) was 1.17 ± 0.30, indicating generally weak-to-moderate wavelength dependence, with occasional enhancement of short-wavelength absorption. Based on empirical AAE intervals, 56% of the samples had values between 1.0 and 1.5, 32% had values below 1.0, and 12% exhibited values above 1.5, indicating enhanced short-wavelength absorption during a limited number of events. These intervals provide qualitative information on spectral variability rather than unambiguous source attribution. Overall, this study provides new multi-wavelength optical observations of PM2.5 from a six-week field campaign conducted in Lahore during March–April 2025 and contributes to the characterization of carbonaceous aerosols in the Indo-Gangetic Plain. The generated dataset provides a useful basis for future source-apportionment studies, air-quality management, and assessments of aerosol radiative effects in highly polluted South Asian urban environments.

Atmospheric simulation chambers are one of the best available tools to study atmospheric processes, as they enable experiments under conditions that are both reproducible and well-controlled. 16 unique simulation chamber facilities are part of the distributed pan-European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). Their research focuses on fundamental gas-phase reaction kinetics, complex reaction mechanisms, aerosol formation and cloud chemistry, as well as other aspects of atmospheric processes. They use both simplified and complex air mixtures in their research. Results of chamber experiments enable the discovery of unknown chemical mechanisms and the determination of physicochemical parameters of atmospheric constituents. Simulation chambers are ideal for testing instruments and quality assurance of their data. The variability of their research capability is reflected in differences in the size (ranging from approximately 1-270 m3), the wall material, and the type of instrumentation used to measure physical parameters, gas-phase species, physicochemical properties of aerosol particles as well as cloud droplets and ice crystals. Most chambers in ACTRIS are indoors and use artificial light sources to initiate photochemical reactions while some chambers are located outside so that natural sunlight can be used. During experiments, steady state conditions may be achieved, the evolution of initial conditions may be observed, or expansion and mixing techniques may induce cloud formation. In this paper, the ACTRIS simulation chambers are described along with the quality control measures for carrying out experiments and reporting data. An overview of how users from the research community and industry can gain access to the ACTRIS simulation chambers and associated data centre is presented. Recent developments in the application of ACTRIS simulation chambers for answering current and future atmospheric research questions are discussed.

Mineral desert dust is a major contributor to total atmospheric particulate matter1. Desert dust outbreaks degrade air quality and can pose adverse health effects2, including asthma exacerbation3 and increased mortality4. At some European locations, there has been a rise in the intensity and frequency of transported dust outbreaks from deserts in recent decades5-9. However, it remains unclear whether this increase is consistent across Europe and whether desertification and aridity or shifts in atmospheric circulation are the main drivers behind this rise. Here we compile a database of daily dust metal concentrations from European sites, establishing robust elemental ratios for transported dust. Using this database, we develop a machine learning model to estimate daily PM10 (particulate matter smaller than 10 μm) dust concentrations from 2012 to 2021, ranging from 2.09 ± 1.05 μg m-3 across northern and central Europe to 5.28 ± 2.65 μg m-3 across the south. In southern Europe, residents are exposed to transported dust events averaging 9.68 ± 4.85 μg m-3, linked to a 0.67 ± 0.02% rise in daily mortality. Intensified dust intrusions over the past decade are linked to shifts in atmospheric circulation. Data from an Alpine ice core record shows a 110% increase in dust concentrations since pre-industrial times, mostly associated with North African desertification. As climate change accelerates land degradation and affects weather patterns, worsening dust pollution may pose increasing risks to public health and air quality goals.

Bioaerosol is a significant element of Particulate Matter (PM) and comprises various components, with bacterial species ranking as some of the most important. Reliable and consistent bioaerosol generators are essential for the investigation of bioaerosol in laboratory environments. Aerosol generators are utilized to evaluate the performance of bioaerosol collectors, explore the transport and deposition of biological particles, and study the health impacts and exposure to airborne microorganisms. The main goal of the bacteria experiments is to have an aerosol generator able to aerosolize the maximum number of viable and culturable cells at elevated particle concentrations. This study performs a comparative investigation of two bioaerosol generators: the Sparging Liquid Aerosol Generator (SLAG) by CH Technologies and the 1520 Flow Focusing Monodisperse Aerosol Generator (FMAG) by TSI. The analysis concentrated on the vitality, culturability, fragmentation, and nebulization efficiency of E. coli cells. The results indicated increased fragmentation using the SLAG nebulizer, and the size distribution varied according to the concentration of the injection fluid for FMAG. Both nebulizers imposed significant stress on bacteria during nebulization, halving their viability. Ultimately, the nebulization efficiency of FMAG is twenty times higher than that of SLAG.

Per- and polyfluoroalkyl substances (PFAS) are recognised as atmospheric contaminants, yet processes governing their aerosol formation, size distribution, and interactions with atmospheric particle surfaces remain unknown. We investigated aerosolisation and size-resolved behaviour of 25 PFAS covering short-, medium-, and long-chain perfluoroalkyl carboxylic acids (PFCA), perfluoroalkane sulfonates, fluorotelomer sulfonates and emerging alternatives. Experiments were conducted under controlled chamber conditions using a water-organic solvent system, in the absence/presence of the model bacterium Pseudomonas fluorescens seed to investigate the potential influence of microbial presence on PFAS behaviour. Most PFAS exhibited unimodal mass-size distributions peaking at 0.3 & micro;m, indicating dominant association with the fine mode. Sulfonated PFAS showed broadly similar aerosol-phase concentrations regardless of carbon-chain length, whereas PFCA displayed increasing aerosolisation with chain length. Perfluorooctane sulfonic acid (PFOS) showed additional ultrafine enrichment, 6:2 fluorotelomer sulfonate (6:2 FTS) and sodium 4,8-dioxa-3H-perfluorononanoate (NaDONA) exhibited broader size profiles, suggesting compound-specific effects linked to volatility and interfacial behaviour. Pseudomonas fluorescens seed did not enhance PFAS aerosol concentrations through condensation or heterogeneous uptake onto bacterial particles or shift in modal diameters, and no enrichment was observed at bacterial size mode, indicating limited PFAS-bioaerosol association under the tested conditions. Multiple-Path Particle Dosimetry (MPPD) modelling based on the measured size distributions predicted substantial deposition of the aerosol-bound PFAS in the pulmonary region, particularly for compounds enriched in ultrafine particles. Our findings indicate that PFAS aerosol behaviour in mixed-solvent systems is controlled primarily by physical droplet generation and evaporation, with implications for airborne transport and inhalation exposure from contaminated aqueous sources.

In today's rapidly evolving society, the sources of atmospheric particulate matter (PM) emissions are shifting significantly. Stringent regulations on vehicle tailpipe emissions, in combination with a lack of control of non-exhaust vehicular emissions, have led to an increase in the relative contribution of non-exhaust PM in Europe. This study analyzes the spatial distribution, temporal trends, and impacts of brake wear PM pollution across Europe by modeling copper (Cu) concentrations at a high spatial resolution of ∼250 m which is a key tracer of brake-wear emissions. We integrated coarse-resolution brake-wear Cu from CAMx chemical transport model and high-resolution land use data into a random forest (RF) model to predict Cu concentrations at ∼250 m over whole of continental Europe. The RF model was trained using an unprecedented dataset of over 50,000 daily Cu measurements from 152 sites. It corrected CAMx underestimation and downscaled Cu to a higher spatial resolution. In validation, the model showed robust spatial and temporal prediction with good Pearson's correlation coefficients of 0.6 and 0.7, respectively. We generated 10 years (2010-2019) of daily Cu concentrations over Europe, revealing spatial patterns aligned with urbanization and road networks, with peaks in cities and lower values in rural areas. Temporal trends reveal that Cu concentrations generally peak on weekdays and in winter. Despite a decline in PM across Europe over decades, Cu concentrations showed no decrease in many cities from 2010 to 2019. Cu levels are strongly correlated with population density with more than 12 million Europeans exposed to levels exceeding 40 ng/m3, equivalent to around 1 μg/m3 of total PM10 from brake wear. Our findings highlight the need for expanded metal measurement for non-exhaust tracers for a better understanding of the health relevance of PM composition including Cu, and more effective regulations of non-exhaust PM emissions as included in EURO 7 vehicles.

Airborne biological particles, such as pollen, fungi, bacteria, viruses, and plant or animal detritus, are known as bioaerosols. Understanding bioaerosols’ behavior, especially their reaction to pollutants and atmospheric conditions, is crucial for addressing environmental and health issues related to air quality. Such complex investigations can benefit from experiments in controlled but realistic environments, such as the Atmospheric Simulation Chamber facility ChAMBRe (Chamber for Aerosol Modeling and Bio-aerosol Research). In this work, we report on the results of several experiments that were conducted at ChAMBRe using three strains of bacteria: E. coli, B. subtilis, and P. fluorescens. The goal of these experiments was to quantitively study how the culturability of these bacteria is affected by exposure to NO, NO2, and light. The experimental approach was simple but carefully controlled: before being introduced into ChAMBRe, the bacteria samples were characterized using three different methods to determine the ratio of viable to total bacteria. The bacteria suspension was then aerosolized and introduced into ChAMBRe, where it was exposed to two different concentrations of NO and NO2, in dark conditions and with simulated solar radiation. The culturability of the bacteria was assessed by collecting bacteria samples directly onto Petri dishes by an Andersen impactor at various time intervals after the end of injection. Finally, the formed bacteria colonies were counted after 24–48 h of incubation to measure their culturability and the temporal trend. The results show a reduction of culturability for all bacteria strains when exposed to NO2 (from 50 to 70%) and to high concentrations of NO (i.e. around 30% at more than 1200 ppb) at concentration values higher than the typical urban ambient values. Even higher effects were observed exposing the bacteria strain to a proxy of solar light. The findings show how atmospheric simulation chambers help the comprehension of interactions between pollutants and bioaerosols in controlled atmospheric environments.

Bioaerosol is generally defined as solid airborne particles of biological origin suspended in the gaseous medium ubiquitously with an aerodynamic diameter of up to 100 µm. They can either be naturally released from the biosphere to the atmosphere or are released due to human activities. Here, we present the results of several experiments, performed inside a confined and controlled artificial environment, such as the Atmospheric Simulation Chamber, providing valuable information on bio-aerosol viability, dispersion, and impact. At ChAMBRe (Chamber for Aerosol Modelling and Bio-aerosol Research), managed by INFN at the Physics Department of the University of Genoa, Italy, the research on bioaerosol is focused on the investigation of the airborne bacteria behavior in different atmospheric and air quality conditions (Massabò et al., 2018). A multi-step protocol was developed (Vernocchi et al, 2023) and thoroughly tested to cultivate a suitable bacteria population (E. coli, B. subtilis, B. licheniformis, and P. fluorescens). Then, bacteria are nebulized, and injected inside ChAMBRe, where they are exposed to different gas concentration values. The viability variation, due to the pollutant exposure inside ChAMBRe, was determined by monitoring the concentration of viable bacteria. The bacteria survival rate inside ChAMBRe is first evaluated by a set of baseline experiments (clean air condition) and successively exposing the bacterial strands to NO2 and NO concentration values up to 1200 ppb for both pollutants. A WIBS-NEO instrument measured bacteria total concentration inside ChAMBRe while the viable concentration was determined by active sampling on Petri dishes by an Andersen impactor and then counting the Colonies Forming Units (CFU). In addition, a liquid impinger was used to maintain the integrity of the microorganisms and their physiological state to investigate a sampling strategy to assess viability and simultaneously cultivability, taking into account the VBNC status (viable but not cultivable). To this end, we present the results of impactor experiments and preliminary assessments with live and dead assays examined by fluorescence microscopy for quantitative and qualitative analysis.ReferencesMassabò, D., Danelli, S. G., Brotto, P., Comite, A., Costa, C., Di Cesare, A., Doussin, J. F., Ferraro, F., Formenti, P., Gatta, E., Negretti, L., Oliva, M., Parodi, F., Vezzulli, L., and Prati, P.: ChAMBRe: a new atmospheric simulation chamber for aerosol modelling and bio-aerosol research, Atmos. Meas. Tech., 11, 5885–5900, https://doi.org/10.5194/amt-11-5885-2018, 2018.Vernocchi, V., Abd El, E., Brunoldi, M., Danelli, S. G., Gatta, E., Isolabella, T., Mazzei, F., Parodi, F., Prati, P., and Massabò, D. (2023) Atmos. Meas. Tech., 16, 5479–5493. https://doi.org/10.5194/amt-16-5479-2023, 2023.

We introduce a new instrument to measure spectral light absorption by aerosol particles. BLAnCA (Broadband Light Analyzer of Complex Aerosol) is an automatic laboratory instrument for offline measurement of aerosol collected on suitable media. BLAnCA is equipped with a white light source and a high-resolution spec-trometer, and measures in the range between 375 and 1000 nm with a spectral resolution of 5 nm. This allows for the determination of fine structure of the ab-sorption properties of a sampled aerosol, which can lead to improvement in the robustness and scope of source apportionment and the evaluation of climate-relevant properties such as the aerosol mass absorption cross-section. The new instrument has been validated against a multi-wavelength absorbance analyzer, obtaining an agreement of up to 99 % between absorption coefficient measurements. The absorption coefficient limit of detection for BLAnCA has been estimated at 1.20 Mm-1 (2.70 Mm-1 ) for standard EU (EPA) sampling conditions, corresponding to an elemental carbon detection limit of about 1.3 mu g cm-2 , if a mass absorption cross-section of 4.7 m 2 g-1 at 1000 nm is considered. The instrument has been used to characterize several types of aerosol samples, each with its own distinct absorp-tion features, which show the potential for BLAnCA to identify different kinds of particulate matter based on their optical properties.

Abstract. The joint use of hourly resolution sampling and analyses with accelerated ion beams such as Particle Induced X-ray Emission (PIXE) technique has allowed the measurement of hourly temporal patterns of particulate matter (PM) composition at many sites in different parts of the world. The demand within the scientific community for this type of analysis has been continuously increasing in recent years, but hourly resolution samplers suitable for PIXE analysis are now discontinued and/or suffer from some technical limitations. In this framework, a new hourly sampler, STRAS (Size and Time Resolved Aerosol Sampler), was developed for the collection of PM10, PM2.5 or PM1. It allows automatic sequential sampling of up to 168 hourly samples (1 week), it is mechanically robust, compact, and easily transportable. To increase PIXE sensitivity, each sample is concentrated on a small surface area on a polycarbonate membrane. The comparison between the elemental concentrations retrieved by STRAS samples and samples collected using a standard sequential sampler operated in parallel shows a very good agreement; indeed, if both the samplers use the same kind of membrane, the concentrations of all detected elements are in agreement within 10 %.

In this paper, we applied the Dispersion Normalised Positive Matrix Factorisation (DN-PMF) approach recently proposed in the literature to provide a more realistic picture of the relative importance of emission strength vs. atmospheric dispersion conditions. The disentanglement of such effects is of great concern in pollution hot spots like the Po Valley (Italy), where particulate matter limit values are exceeded despite the existing abatement measures. To explore the potentiality of the DN-PMF approach - still scarcely applied in the literature - a well -chemically characterised PM1 (atmospheric particles with aerodynamic diameter <1 mu m) dataset comprising samples collected at different time resolutions at an urban background site (Bologna) in the southern Po Valley was used. Indeed, it is well known that shallow mixing layers promote pollutant accumulation but this obser-vation is not enough to exclude an enhancement of emission strength which could be tackled by appropriate abatement strategies.The source apportionment of sub-micron sized aerosols having a quite long atmospheric residence time in a complex environment like the Po Valley -which is also strongly impacted by secondary aerosol formation on a basin-scale -is generally quite challenging when using receptor models. Due to the availability of a huge dataset with variables having multiple time resolutions, in this work the DN-PMF was implemented in a multi-time resolution approach (MT) to achieve a better source identification and to gain knowledge about the relative importance of atmospheric dilution vs. emissions. A comparison between results obtained by the application of the regular multi time resolution (REG-MT) vs. the DN-MT approach is presented here for the five factors identified (nitrate-dominated, sulphate-dominated, biomass burning, mineral dust, and urban aerosol). The first interesting outcome is that REG-MT and DN-MT results do not point at significant differences in temporal pat-terns for aerosol components and sources impacting at the basin-scale (i.e. sulphate-and nitrate-dominated aerosol, biomass burning) thus suggesting that the diel modulation of these PM1 emissions is somehow masked by the stronger variability of the mixing layer. Conversely, contributions from local sources with more pronounced diel variation like traffic are quite well reproduced by DN-MT and the ambient concentrations are enhanced compared to REG-MT. This is an important piece of information highlighting that PM1 concentrations from local sources have been likely underestimated by REG-MT assessments.To our knowledge, this is one of the very few applications of DN-MT and the first one at a European site where the huge effort made to implement air pollution containment measures is still not very much effective in reducing PM levels; moreover, in this paper a detailed discussion about the possible interpretation of the output of DN-MT in terms of temporal patterns is reported.

The CNO cycle is one of the most important nuclear energy sources in stars. At temperatures of hydrostatic H-burning (20  MK<T<80  MK) the ^{17}O(p,γ)^{18}F reaction rate is dominated by the poorly constrained 64.5 keV resonance. Here, we report on the first direct measurements of its resonance strength and of the direct capture contribution at 142 keV, performed with a new high sensitivity setup at LUNA. The present resonance strength of ωγ_{(p,γ)}^{bare}=(30±6_{stat}±2_{syst})  peV is about a factor of 2 higher than the values in literature, leading to a Γ_{p}^{bare}=(34±7_{stat}±3_{syst})  neV, in agreement with the LUNA result from the (p,α) channel. Such agreement strengthens our understanding of the oxygen isotopic ratios measured in red giant stars and in O-rich presolar grains.

Instruments measuring aerosol light absorption, such as the Aethalometer and the Multi-Wavelength Absorbance Analyzer (MWAA), have been extensively used to characterize optical absorption of atmospheric particulate matter. Data retrieved with such instruments can be analysed with mathematical models to apportion different aerosol sources (Aethalometer model) and components (MWAA model). In this work we present an upgrade to the MWAA optical apportionment model. In addition to the apportionment of the absorption coefficient babs in its components (black carbon and brown carbon) and sources (fossil fuels and wood burning), the extended model allows for the retrieval of the absorption Ångström exponent of each component and source, thereby avoiding initial assumptions regarding these parameters. We also present a new open-source software toolkit, the MWAA model toolkit (MWAA_MT), written in both Python and R, that performs the entire apportionment procedure.

The D(p, gamma ) 3He reaction, where 'D' denotes '2H', is of primary importance in cosmology and nuclear physics since it offers a unique opportunity to test predictions based on the description of nuclear interactions. We present a novel approach to extract the angular distribution of the photons emitted by the D(p, gamma ) 3He reaction inferred from the shape of the experimental gamma spectra. The measurement was performed in the Gran Sasso Laboratories by the LUNA collaboration. By using a HPGe detector faced to an extended deuterium gas target, it was possible to derive the angular distribution in the 30-280 keV kinetic energy range and to compare the results with recent ab initio predictions.

The effects of bioaerosol, the biological component of atmospheric aerosol, on the environment and health are numerous but still little known, studies on the subject are continually growing. Experiments conducted in Atmospheric Simulation Chambers (ASCs), can provide valuable information on the viability, dispersion and interactions of microorganisms in the aerosols. For this purpose, a multi-step experimental procedure was developed; systematic studies have been carried out in our ASC, to expose bioaerosol to controlled atmospheric conditions. This study reports the results of the experiments conducted on Escherichia coli and Bacillus subtilis, , which highlight how the two bacterial strains react, in terms of viability, to the aerosolization process and to remaining in an aerosolized state in controlled atmospheric conditions.

Background: Among the several inhomogeneities in the composition of globular cluster stars, an overabundance of 23 Na is interpreted as the signature of the operation of the neon-sodium (NeNa) cycle. One of the hypothesis to explain the observed O-Na anticorrelation invokes massive asymptotic giant branch stars as the main agents. At temperatures relevant for nucleosynthesis in asymptotic giant branch stars the 22 Ne( p , gamma ) 23 Na reaction rate has been the most uncertain so far, giving rise to considerable experimental efforts in recent years. While overall there is a good agreement between reported cross section results, some tensions still remain on the branching ratios of resonance gamma-ray modes and direct capture to excited sates. Purpose: The present paper offers full details and a partial analysis of the high sensitivity study, of both direct capture and low-energy resonances in the 22 Ne( p , gamma ) 23 Na reaction, performed at LUNA, and whose results were previously published in abbreviated form [F. Ferraro et al. , Phys. Rev. Lett. 121 , 172701 (2018)]. Methods: During the LUNA measurement an intense proton beam was delivered to a 22 Ne gas target. The gamma rays from the 22 Ne( p , gamma ) 23 Na reaction were detected by a high efficiency 4 pi , sixfold segmented bismuth germanate (BGO) detector. In the present paper the data from individual detector segments were combined with simulated detector responses to obtain cascade branching ratios. Results: For the three resonances at E p = 156 . 2 and 259.7 keV new gamma-decay branchings are provided. Moreover, partial cross sections for the direct capture to different states of 23 Na are reported down to E p = 188 keV, the lowest energy measured to date. Conclusions: A revised reaction rate has been calculated based on a new R-matrix fit of the recent 22 Ne( p , gamma ) 23 Na S-factor data and results for the resonances. The thermonuclear reaction rate is provided in tabular form to be used in stellar models.

The airborne transmission of bacterial pathogens poses a significant challenge to public health, especially with the emergence of antibiotic-resistant strains. This study investigated environmental factors influencing the survival of airborne bacteria, focusing on the effects of different carbon dioxide (CO2) and dust concentrations. The experiments were conducted in an atmospheric simulation chamber using the non-resistant wild-type E. coli K12 (JM109) and a multi-resistant variant (JM109-pEC958). Different CO2 (100 ppm, 800 ppm, 3000 ppm) and dust concentrations (250 µg m−3, 500 µg m−3, 2000 µg m−3) were tested to encompass a wide range of CO2 and dust levels. The results revealed that JM109-pEC958 exhibited greater resilience to high CO2 and dust concentrations compared to its non-resistant counterpart. At 3000 ppm CO2, the survival rate of JM109 was significantly reduced, while the survival rate of JM109-pEC958 remained unaffected. At the dust concentration of 250 µg m−3, JM109 exhibited significantly reduced survival, whereas JM109-pEC958 did not. When the dust concentration was increased to 500 and 2000 µg m−3, even the JM109-pEC958 experienced substantially reduced survival rates, which were still significantly higher than those of its non-resistant counterpart at these concentrations. These findings suggest that multi-resistant E. coli strains possess mechanisms enabling them to endure extreme environmental conditions better than non-resistant strains, potentially involving regulatory genes or efflux pumps. The study underscores the importance of understanding bacterial adaptation strategies to develop effective mitigation approaches against antibiotic-resistant bacteria in atmospheric environments. Overall, this study provides valuable insights into the interplay between environmental stressors and bacterial survival, serving as a foundational step towards elucidating the adaptation mechanisms of multi-resistant bacteria and informing strategies for combating antibiotic resistance in the atmosphere.

The C-13(alpha,n)O-16 reaction is the main neutron source of the s-process taking place in thermally pulsing AGB stars and it is one of the main candidate sources of neutrons for the i-process in the astrophysical sites proposed so far. Therefore, its rate is crucial to understand the production of the nuclei heavier than iron in the Universe. For the first time, the LUNA collaboration was able to measure the C-13(alpha,n)O-16 cross section at E c.m. = 0.23-0.3 MeV drastically reducing the uncertainty of the S(E)-factor in the astrophysically relevant energy range. In this paper, we provide details and critical thoughts about the LUNA measurement and compare them with the current understanding of the C-13(alpha,n)O-16 reaction in view of future prospect for higher energy measurements. The two very recent results (from the University of Notre Dame and the JUNA collaboration) published after the LUNA data represent an important step forward. There is, however, still room for a lot of improvement in the experimental study of the C-13(alpha,n)O-16 reaction, as emphasized in the present manuscript. We conclude that to provide significantly better constraints on the low-energy extrapolation, experimental data need to be provided over a wide energy range, which overlaps with the energy range of current measurements. Furthermore, future experiments need to focus on the proper target characterisation, the determination of neutron detection efficiency having more nuclear physics input, such as angular distribution of the C-13(alpha,n)O-16 reaction below E alpha < 0.8 MeV and study of nuclear properties of monoenergetic neutron sources and/or via the study of sharp resonances of C-13(alpha,n)O-16. Moreover, comprehensive, multichannel R-matrix analysis with a proper estimate of uncertainty budget of experimental data are still required.

The CNO cycle is one of the most important nuclear energy sources in stars. At temperatures of hydrostatic H-burning (20 MK