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Our purpose was to test the hypothesis that ultrasonic cigarettes (u-cigarettes), which operate at relatively low temperatures, produce aerosols that are less harmful than heated-coil pod-style electronic cigarettes (e-cigarettes). The major chemicals in SURGE u-cigarette fluids and aerosols were quantified, their cytotoxicity and cellular effects were assessed, and a Margin of Exposure risk assessment was performed on chemicals in SURGE fluids. Four SURGE u-cigarette flavor variants (Blueberry Ice, Watermelon Ice, Green Mint, and Polar Mint) were evaluated. Flavor chemicals were quantified in fluids and aerosols using gas chromatography/mass spectrometry. Cytotoxicity and cell dynamics were assessed using the MTT assay, live-cell imaging, and fluorescence microscopy. WS-23 (a coolant) and total flavor chemical concentrations in SURGE were similar to e-cigarettes, while SURGE nicotine concentrations (13-19 mg/mL) were lower than many fourth generation e-cigarettes. Transfer efficiencies of dominant chemicals to aerosols in SURGE ranged from 44-100%. SURGE fluids and aerosols had four dominant flavor chemicals (>1 mg/mL). Toxic aldehydes were usually higher in SURGE aerosols than in SURGE fluids. SURGE fluids and aerosols had aldehyde concentrations significantly higher than pod-style e-cigarettes. Chemical constituents, solvent ratios, and aldehydes varied among SURGE flavor variants. SURGE fluids and aerosols inhibited cell growth and mitochondrial reductases, produced attenuated and round cells, and depolymerized actin filaments, effects that depended on pod flavor, chemical constituents, and concentration. The MOEs for nicotine, WS-23, and propylene glycol were

Environmentally persistent free radicals (EPFRs) play an important role in aerosol effects on air quality and public health, but their atmospheric abundance and sources are poorly understood. We measured EPFRs contained in PM2.5 collected in Fairbanks, Alaska, in winter 2022. We find that EPFR concentrations were enhanced during surface-based inversion and correlate strongly with incomplete combustion markers, including carbon monoxide and elemental carbon (R2 > 0.75). EPFRs exhibit moderately good correlations with PAHs, biomass burning organic aerosols, and potassium (R2 > 0.4). We also observe strong correlations of EPFRs with hydrocarbon-like organic aerosols, Fe and Ti (R2 > 0.6), and single-particle mass spectrometry measurements reveal internal mixing of PAHs, with potassium and iron. These results suggest that residential wood burning and vehicle tailpipes are major sources of EPFRs and nontailpipe emissions, such as brake wear and road dust, may contribute to the stabilization of EPFRs. Exposure to the observed EPFR concentrations (18 ± 12 pmol m-3) would be equivalent to smoking ∼0.4-1 cigarette daily. Very strong correlations (R2 > 0.8) of EPFR with hydroxyl radical formation in surrogate lung fluid indicate that exposure to EPFRs may induce oxidative stress in the human respiratory tract.

Photothermal spectroscopy, and more specifically photothermal interferometry (PTI), is a highly sensitive technique for measuring gas and aerosol concentrations. Numerous implementations of different PTI configurations have demonstrated the versatility of the technique. This theoretical study presents a comprehensive analysis and an optimization of the PTI optical path length (OPL) amplitude using characteristic times. We investigate how the OPL amplitude depends on the dimensions and orientations of the interferometer laser beam and the continuous-wave excitation laser beam. This analysis quantifies the impact of advection on the OPL amplitude based on the relative orientation of the two laser beams and the gas flow direction. It is analytically shown that the possibilities for photothermal OPL amplitude optimization are limited when thermal diffusion is dominant. Theoretically, advection has the potential to double or cancel the OPL amplitude, depending on the specific configurations. In summary, we provide an in-depth understanding of the design and parameter considerations required when tailoring and optimizing a PTI sensor for different fields of applications. [ABSTRACT FROM AUTHOR]

The production of e-cigarette aerosols through vaping processes is known to cause the formation of various free radicals and reactive oxygen species (ROS). Despite the well-known oxidative potential and cytotoxicity of fresh vaping emissions, the effects of chemical aging on exhaled vaping aerosols by indoor atmospheric oxidants are yet to be elucidated. Terpenes are commonly found in e-liquids as flavor additives. In the presence of indoor ozone (O3), e-cigarette aerosols that contain terpene flavorings can undergo chemical transformations, further producing ROS and reactive carbonyl species. Here, we simulated the aging process of the e-cigarette emissions in a 2 m3 FEP film chamber with 100 ppbv of O3 exposure for an hour. The aged vaping aerosols, along with fresh aerosols, were collected to detect the presence of ROS. The aged particles exhibited 2- to 11-fold greater oxidative potential, and further analysis showed that these particles formed a greater number of radicals in aqueous conditions. The aging process induced the formation of various alkyl hydroperoxides (ROOH), and through iodometric quantification, we saw that our aged vaping particles contained significantly greater amounts of these hydroperoxides than their fresh counterparts. Bronchial epithelial cells exposed to aged vaping aerosols exhibited an upregulation of the oxidative stress genes, HMOX-1 and GSTP1, indicating the potential for inhalation toxicity. This work highlights the indirect danger of vaping in environments with high ground-level O3, which can chemically transform e-cigarette aerosols into new particles that can induce greater oxidative damage than fresh e-cigarette aerosols. Given that the toxicological characteristics of e-cigarettes are mainly associated with the inhalation of fresh aerosols in current studies, our work may provide a perspective that characterizes vaping exposure under secondhand or thirdhand conditions as a significant health risk.

The reaction of peracetic acid (PAA) and Fe(II) has recently gained attention due to its utility in wastewater treatment and its role in cloud chemistry. Aerosol-cloud interactions, partly mediated by aqueous hydroxyl radical (OH) chemistry, represent one of the largest uncertainties in the climate system. Ambiguities remain regarding the sources of OH in the cloud droplets. Our research group recently proposed that the dark and light-driven reaction of Fe(II) with peracids may be a key contributor to OH formation, producing a large burst of OH when aerosol particles take up water as they grow to become cloud droplets, in which reactants are consumed within 2 min. In this work, we quantify the OH production from the reaction of Fe(II) and PAA across a range of physical and chemical conditions. We show a strong dependence of OH formation on ultraviolet (UV) wavelength, with maximum OH formation at λ = 304 ± 5 nm, and demonstrate that the OH burst phenomenon is unique to Fe(II) and peracids. Using kinetics modeling and density functional theory calculations, we suggest the reaction proceeds through the formation of an [Fe(II)-(PAA)2(H2O)2] complex, followed by the formation of a Fe(IV) complex, which can also be photoactivated to produce additional OH. Determining the characteristics of OH production from this reaction advances our knowledge of the sources of OH in cloudwater and provides a framework to optimize this reaction for OH output for wastewater treatment purposes.

Within aerosol-rich environments, efficient simulation of frequency-modulated continuous wave (FMCW) laser detector echo characteristics is crucial. Conventional methods often need more efficiency. To address this, we propose a photon matrix-based approach for simulating intricate photon scattering processes, enhancing simulation accuracy. This study focuses on short-range FMCW laser detection under aerosol interference, assessing performance via signal-to-noise ratio (SNR). We analyze the impact of amplitude modulation coefficient and photon count on SNR. Surprisingly, the photon count minimally affects SNR, while the amplitude modulation coefficient significantly influences it. These findings shed light on optimizing FMCW laser detection in aerosol-laden environments. Attention to the amplitude modulation coefficient can notably enhance SNR and overall detection efficiency. [ABSTRACT FROM AUTHOR]

We develop a model for the thermodynamics and evaporation dynamics of aerosol droplets of a liquid, such as water, surrounded by gas. When the temperature and the chemical potential (or equivalently the humidity) are such that the vapor phase is in the thermodynamic equilibrium state, then, of course, droplets of the pure liquid evaporate over a relatively short time. However, if the droplets also contain nanoparticles or any other non-volatile solute, then the droplets can become thermodynamically stable. We show that the equilibrium droplet size depends strongly on the amount and solubility of the nanoparticles within, i.e., on the nature of the particle interactions with the liquid and, of course, also on the vapor temperature and chemical potential. We develop a simple thermodynamic model for such droplets and compare predictions with results from a lattice density functional theory that takes as input the same particle interaction properties, finding very good agreement. We also use dynamical density functional theory to study the evaporation/condensation dynamics of liquid from/to droplets as they equilibrate with the vapor, thereby demonstrating droplet stability. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to verify that aerosolization ocular surface microorganisms (AOSMs) accumulated during non-contact tonometry (NCT) measurements. Methods: A total of 508 participants (740 eyes) were enrolled in the study. In Experiment 1, before NCT was performed on each eye, the air was disinfected, and environment air control samples were collected via Air ideal® 3P (Bio Merieux). During NCT measurements, microbial aerosol samples were collected once from each eye. In Experiment 2, we collected initial blank control samples and then repeated Experiment 1. Finally, in Experiment 3, after the background microbial aerosol investigation, we cumulatively sampled AOSMs from each 10 participants then culture once, without any interventions to interrupt the accumulation. The collected samples were incubated and identified using matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Results: Pathogenic Aerococcus viridans and other microorganisms from human eyes can spread and accumulate in the air during NCT measurements. The species and quantity of AOSMs produced by NCT measurements can demonstrate an accumulation effect. Conclusion: AOSMs generated during NCT measurements are highly likely to spread and accumulate in the air, thereby may increase the risk of exposure to and transmission of bio-aerosols. Precis: Pathogenic Aerococcus viridans and other species of aerosolization ocular surface microorganisms (AOSMs) can spread and accumulate with the increase of NCT measurement person times, demonstrating an accumulation effect. [ABSTRACT FROM AUTHOR]

Global and South African populations continue to increase exponentially, with large flows of persons into urban centres. Urban air quality and bioaerosol are therefore becoming an increasingly important consideration in the face of a growing burden of allergic respiratory diseases. More than 20% of South Africans have asthma, with morbidity being disproportionately high compared to high-income countries (HICs). Air pollutants (particularly particulate matter and ozone), pollen and fungal spores are known triggers and exacerbating factors in asthma and, alarmingly, the levels of air pollutants remain high in hotspot areas despite robust air-quality legislation in South Africa. The concern is that genetically and environmentally vulnerable children in low- and middle-income countries (LMICs) such as South Africa will have asthma triggered and exacerbated disproportionately by poor air quality. Urban green areas are increasingly being recognised by many stakeholders as important possible mitigation tools. However, multiple factors must be considered for having an optimal green space design. In this review, we bring together experts across the fields of health, air quality and aerobiology to outline the intersection between asthma and air quality and/or aerobiology in South Africa. We highlight the importance of careful multidisciplinary green space design as a possible healing tonic. We conclude that detailed studies combining air quality, pollen dispersal and health issues are needed to derive more precise exposure--response functions of the green spaces in South Africa and other LMICs. [ABSTRACT FROM AUTHOR]

Aerosol science is of utmost importance for both climate and public health research, and in recent years X‐ray techniques have proven effective tools for aerosol‐particle characterization. To date, such methods have often involved the study of particles collected onto a substrate, but a high photon flux may cause radiation damage to such deposited particles and volatile components can potentially react with the surrounding environment after sampling. These and many other factors make studies on collected aerosol particles challenging. Therefore, a new aerosol sample‐delivery system dedicated to X‐ray photoelectron spectroscopy studies of aerosol particles and gas molecules in‐flight has been developed at the MAX IV Laboratory. The aerosol particles are brought from atmospheric pressure to vacuum in a continuous flow, ensuring that the sample is constantly renewed, thus avoiding radiation damage, and allowing measurements on the true unsupported aerosol. At the same time, available gas molecules can be used for energy calibration and to study gas‐particle partitioning. The design features of the aerosol sample‐delivery system and important information on the operation procedures are described in detail here. Furthermore, to demonstrate the experimental range of the aerosol sample‐delivery system, results from aerosol particles of different shape, size and composition are presented, including inorganic atmospheric aerosols, secondary organic aerosols and engineered nanoparticles. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols partly compensate for the warming due to greenhouse gases by perturbing the radiation balance of the Earth–Atmosphere system. In this study, the impacts of aerosols on surface temperature are examined over the Indo-Gangetic Plain (IGP) and Himalayan Tibetan Plateau (HTP), where diverse aerosol and climatic conditions prevail. Both regions have significant impacts on the regional climate and hydrological cycles in South Asia. The IGP experiences high aerosol loading throughout the year and is expected to affect surface temperature significantly. In contrast, the HTP exhibits relatively pristine or lower aerosol loading, whose effects on surface temperature are highly uncertain due to snow albedo feedback. Climate model simulations are used to decompose the surface temperature changes due to aerosol forcing to its radiative and non-radiative components over the IGP and HTP. The shortwave cooling due to aerosols is mostly compensated by the decrease in sensible heat over the IGP. On the other hand, HTP experiences surface cooling due to the direct effects and surface warming due to aerosol-induced snow-darkening effects (deposition of absorbing aerosols on snow). The net effect of aerosols on shortwave radiation is further redistributed into non-radiative heat fluxes. This study provides a better understanding of aerosol-induced surface temperature change and its partitioning into radiative and non-radiative components. [ABSTRACT FROM AUTHOR]

The effects of polydisperse aerosol slit and classified aerosol outlet widths on the performance of a cylindrical differential mobility analyzer (DMA) were investigated using numerical simulations and measurements. The approach was verified by comparing the MF-DMA experimental voltages with numerical results. The study shows that the polydisperse aerosol slit width plays an important role in the performance of a cylindrical DMA and has an optimal value. When deviating from this optimal value, the DMA resolution decreases, specifically, increasing the radial ratio and aspect ratio while decreasing the optimal value. However, the enhanced classification length increases the resolution. It is also shown that the performance of DMA deteriorates as the classified aerosol outlet width increases. [ABSTRACT FROM AUTHOR]

Studying the elemental composition of aerosol particles on a single particle level is of importance when determining the internal and external mixing state of the aerosol population. We present a field-deployable platform for the elemental analysis of ambient single particles using laser-induced breakdown spectroscopy (LIBS). The platform utilizes a wideband spectrometer for simultaneous multi-element detection and size-amplification-aided aerosol charging (SAAC) for efficient particle focusing via a linear electrodynamic quadrupole (LEQ). Carefully designed emission collection system allows minimization of the plasma background emission, which allows us to use short gate delays for increased yield of analyte emission. Performance evaluation with a set of well-defined salt aerosols show excellent capability in determining the relative mass percentage and absolute mass of elements spanning multiple orders of magnitude on a single particle level. Limits of detection for Mg, Na and K were determined to be approximately 2 fg, 40 fg, and 70 fg, respectively. An outdoor aerosol sample was analyzed in the size range of 1–3 µm in diameter, and the particles were classified into distinct categories based on their elemental composition. The maximum analysis speed is about 20 particles per minute and the minimum detectable particle size is, depending on the constituent elements, about 300–800 nm. Emission signals of Al, B, C, Ca, Cu, Fe, K, Mg, Na, Si, and Ti were detected during the measurements of generated or outdoor aerosols. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-flow nasal cannula (HFNC) systems employ different methods to provide aerosol to patients. This study compared delivery efficiency, particle size, and regional deposition of aerosolized bronchodilators during HFNC in neonatal, pediatric, and adult upper-airway and lung models between a proximal aerosol adapter and distal aerosol circuit chamber. METHODS: A filter was connected to the upper airway to a spontaneously breathing lung model. Albuterol was nebulized using the aerosol adapter and circuit at different clinical flow settings. The aerosol mass deposited in the upper airway and lung was quantified. Particle size was measured with a laser diffractometer. Regional deposition was assessed with a gamma camera at each nebulizer location and patient model with minimum flow settings. RESULTS: Inhaled lung doses ranged from 0.2-0.8% for neonates, 0.2-2.2% for the small child, and 0.5-5.2% for the adult models. Neonatal inhaled lung doses were not different between the aerosol circuit and adapter, but the aerosol circuit showed marginally greater lung doses in the pediatric and adult patient models. Impacted aerosols and condensation in the non-heated HFNC and aerosol delivery components contributed to the dispersion of coarse liquid droplets, high deposition (11-44%), and occlusion of the supine neonatal upper airway. In contrast, the upright pediatric and adult upper-airway models had minimal deposition (0.3-7.0%) and high fugitive losses (~24%) from liquid droplets leaking out of the nose. The high impactive losses in the aerosol adapter (56%) were better contained than in the aerosol circuit, resulting in less cannula sputter (5% vs 22%), fewer fugitive losses (18% vs 24%), and smaller inhaled aerosols (5 µm vs 13 µm). CONCLUSIONS: The inhaled lung dose was low (1-5%) during HFNC. Approaches that streamline aerosol delivery are needed to provide safe and effective therapy to patients receiving aerosolized medications with this HFNC system. [ABSTRACT FROM AUTHOR]

Statement of the Problem: Chemotherapy-induced mucositis is the most common complication during cancer treatment. This complication can lead to pain, increased risk of infection and malnutrition. Therefore, it is important to find a solution to reduce the severity and duration of side effects. Purpose: This study aimed to assess the efficacy of Mucosamin spray as an adjunct for prevention of oral mucositis in children under chemotherapy. Materials and Method: This parallel-design clinical trial evaluated 48 patients aged 5 to 15 years with leukemia and lymphoma presenting to the Hematology Department of Mofid and Mahak Hospitals. The patients were randomly divided into two groups (n=24). Before starting chemotherapy, all patients received oral hygiene instructions (toothbrushing without flossing). Patients in both groups were requested to use a mouthwash composed of nystatin, aluminum-magnesium hydroxide suspension (aluminum MgS), and diphenhydramine for 1 min every morning on a daily basis starting the day before treatment. Patients in the intervention group were also requested to spray their entire oral mucosa with Mucosamin spray 3 times a day in addition to using the mouthwash. Patients were requested to refrain from eating and drinking for 1h after spraying. The patients were clinically examined by a senior dental student once every other day for 20 days regarding the occurrence, severity, and duration of oral mucositis. Data were analyzed using the Chi-square and Mann-Whitney tests, Kaplan-Meier survival analysis, and log rank test. Results: No significant difference was noted between the two groups in the incidence, severity, or time of development of mucositis (p> 0.05). The 7-day non-recovery percentage was 72.7% (SE= 13.4) and 25.0% (SE= 15.3) in the control and test groups, respectively, indicating shorter duration (faster healing) of mucositis in the intervention group (p= 0.01). Conclusion: Within the limitations of this study, it seems that prophylactic application of Mucosamin spray can shorten the course of oral mucositis, in case of its occurrence. [ABSTRACT FROM AUTHOR]

Electronic cigarettes (ECs) are battery-powered gadgets that heat liquid to produce an aerosol. Nicotine is a primary ingredient in some e-liquids; however, due to a lack of quality control regulations, the nicotine may become tainted, or the measured and labelled values may not correspond. To avoid such issues, it is essential to identify the components that contribute to erroneous nicotine quantification. Herein, the differences between free-base nicotine and nicotine salts are discussed, highlighting the lower volatility of nicotine salts and their longer persistence in the body. Discrepancies were noted in the concentration of nicotine salts in some e-liquid samples, with labelled and measured values of 48 and 68.8 mg/mL, respectively, in one sample, and 24 and 33.1 mg/mL, respectively, in another. Inconsistencies were also observed in e-liquids labelled as nicotine-free: one sample had a nicotine concentration of 21.80 mg/cartridge, while another had a concentration of 23.91 mg/mL. The review also covers differences in the potency, flavour, and storage of nicotine under various conditions. Additionally, the literature suggests that the components in ECs are separated into the liquid and vapour phases; thus, phase selection should be considered to ensure optimal experimental outcomes. For instance, the vapour phase comprises the greatest quantities of volatile organic compounds, even though nicotine has been detected in all phases. Finally, the role of ECs in smoking cessation is discussed. The reviewed findings underscore the need for further research on e-liquids, particularly regarding their long-term clinical effects. [ABSTRACT FROM AUTHOR]

Rationale: The sources and chemical compositions of organic aerosol (OA) exert a significant influence on both regional and global atmospheric conditions, thereby having far‐reaching implications on environmental chemistry. However, existing mass spectrometry (MS) methods have limitations in characterizing the detailed composition of OA due to selective ionization as well as fractionation during cold‐water extraction and solid‐phase extraction (SPE). Methods: A comprehensive MS study was conducted using aerosol samples collected on dusty, clean, and polluted days. To supplement the data obtained from electrospray ionization (ESI), a strategy for analyzing OAs collected using the quartz fiber filter directly utilizing laser desorption ionization (LDI) was employed. Additionally, the ESI method was conducted to explore suitable approaches for determining various OA compositions from samples collected on dusty, clean, and polluted days. Results: In situ LDI has the advantages of significantly reducing the sample volume, simplifying sample preparation, and overcoming the problem of overestimating sulfur‐containing compounds usually encountered in ESI. It is suitable for the characterization of highly unsaturated and hydrophobic aerosols, such as brown carbon‐type compounds with low volatility and high stability, which is supplementary to ESI. Conclusions: Compared with other ionization methods, in situ LDI helps provide a complementary description of the molecular compositions of OAs, especially for analyzing OAs in polluted day samples. This method may contribute to a more comprehensive MS analysis of the elusive compositions and sources of OA in the atmosphere. [ABSTRACT FROM AUTHOR]

Brown carbon (BrC) in China is of great interest to the regional and global climate due to its strong absorption of sunlight. However, the contribution of BrC to total carbonaceous aerosol light absorption and its direct radiative effects (DRE) in China remains largely uncertain. To better assess its climate impact in China, we develop an explicit BrC scheme and implement it in a global climate model, which includes optical parameters of primary BrC derived from local measurements, secondary BrC absorption, and a photobleaching parameterization of BrC. By comparing with multi‐type observational data, we find that with the implementation of this scheme, the model captures the seasonal variations of BrC light absorption well in China. The model estimates that BrC contributes 19% and 12% to the total light absorption of carbonaceous aerosol in China in winter and summer, resulting in 0.110 and 0.205 W m−2 of DRE, respectively. Plain Language Summary: While the existing research on the direct radiative effects (DRE) of brown carbon (BrC) predominantly focuses on biomass‐burning sources, little attention has been given to BrC originating from anthropogenic sources. Coal combustion and residential fuels used for cooking and heating release many brown carbon aerosols in China. Source of BrC in China is different from that in Europe and North America. Therefore, studying the light‐absorbing properties and climate effects of BrC in China is of great scientific significance. Here, we introduce local optical parameters of primary BrC based on observations in China, secondary BrC absorption, and chemical bleaching of BrC in a global climate model (GCM). We find that the model can simulate the strong seasonal variations of BrC absorption observed in China. With the help of the model and multi‐type measurement data, we estimate the contribution of BrC to the total carbonaceous aerosol absorption and the DRE of BrC in China in different seasons. This study is the first attempt to introduce an explicit BrC scheme in a GCM to estimate the DRE of BrC in China. Key Points: An explicit brown carbon (BrC) scheme is introduced in a climate model together with observations to constrain light absorption of BrCBrC contributes 19% and 12% of total carbonaceous aerosol absorption in China in winter and summer, respectivelySimulated direct radiative effects due to BrC absorption over China are 0.110 and 0.205 W m2 in the winter and summer seasons [ABSTRACT FROM AUTHOR]

This study aimed to measure telomere length in healthy children living next to Urmia Lake, Iran, which is exposed to salt dust from a drying lakebed. In this case-control pilot study, we recruited 39 sex- and age-matched healthy children from two different geographic regions to study the relative telomere lengths using qPCR. We categorized the study samples into high-impact and low-impact areas based on wind direction, aerosol particle level, and distance from the lake. Our main results revealed that children living in high-impact areas have shorter telomeres than those living in low-impact areas. Furthermore, according to our statistical model, parental age significantly affected telomere length in children, but inversely. When the father’s age impact was positive, the mother had a negative effect. Based on our results, to prevent Urmia Lake from dying out completely, national and international organizations should implement comprehensive visions and strategies for its restoration. [ABSTRACT FROM AUTHOR]

With the growth of additive manufacturing (AM), there has been increasing demand for fabricating conformal electronics that directly integrate with larger components to enable unique functionality. However, fabrication of conformal electronics is challenging because devices must merge with host substrates regardless of curvilinearity, topography, or substrate material. In this work, we employ aerosol jet (AJ) printing, an AM method for jet printing electronics using ink-based materials, and a custom-made lathe mechanism for mounting flexible substrates and 3D objects on a rotating axis. Using this method of lathe-based AJ printing, conformal electronics are printed around the circumference of rotational bodies with 3D curvilinear surfaces through cylindrical-coordinate motion. We characterize the diverse capabilities of lathe AJ (LAJ) printing and demonstrate flexible conformal electronics including multilayer carbon nanotube transistors. Lastly, a graphene sensor is conformally printed on an inflated catheter balloon for temperature and inflation monitoring, thus highlighting the versatilities of LAJ printing. [ABSTRACT FROM AUTHOR]

Proteinaceous matter (PrM) is a substantial component of bioaerosols. Although numerous studies have examined the characteristics and sources of PrM in the atmosphere, its interactions with atmospheric oxidants remain uncertain. A 1‐year observation of PrM characteristics in PM2.5 was performed in both urban Nanchang (eastern China) and suburban Guiyang (southwestern China), respectively. Glycine was the dominant free amino acid (FAA) species in urban Nanchang. In contrast, proline dominated both total free amino acids (FAAs) and total combined amino acids (CAAs) in suburban Guiyang. We found that oxidative degradation can significantly promote the release of FAAs, especially glycine, from CAAs in Nanchang. The controlled experiment on protein oxidation by hydroxyl radical suggested that the contribution of free glycine to the total FAA fraction tended to increase during the oxidative degradation of CAAs, supporting the predominance of glycine in FAAs in Nanchang and most previous observations. The composition of FAAs was mainly influenced by primary sources in suburban Guiyang with weak atmospheric degradation of PrM. These results suggest that the degradation of aerosol PrM by atmospheric oxidants can be responsible for the difference in FAA composition between the biosphere and the atmosphere, and also imply that the oxidative degradation of aerosol PrM may be a potential source of secondary organic nitrogen compounds in aerosols. Thus, this study can improve the current understanding of the composition characteristics of PrM in the biosphere and the atmosphere, as well as the liquid phase reactions of proteinaceous compounds with atmospheric oxidants. Plain Language Summary: Proteinaceous matter (PrM) is a ubiquitous component in both the biosphere and the atmosphere, which has seen intense research over years. This study, for the first time, combines a large amount of observational data with controlled experiments to reveal the potential atmospheric transformation of combined and free amino acids. The observed increase in the mass fraction of glycine in the total free amino acids from the biosphere to the atmosphere can be attributed to the fact that glycine has a higher release potential from the oxidative degradation of combined amino acids and is more resistant to further oxidative degradation. The overall results provide field evidence for the strong dependence of free glycine release from aerosol PrM on the hydroxyl radical, likely improving the current understanding of the composition characteristics of PrM and the multiphase reactions of proteinaceous compounds with atmospheric oxidants. Key Points: Atmospheric oxidation can cause an increase in the contribution of Gly to the aerosol TFAA fraction from the biosphere to the atmosphereThe controlled experiment suggests that the contribution of Gly to the TFAA fraction increased during the oxidative degradation of combined amino acidsThe composition profile of aerosol free amino acids depends on the oxidative degradation of proteinaceous matter after release from the biosphere to the atmosphere [ABSTRACT FROM AUTHOR]

The source of dust in the global atmosphere is an important factor to better understand the role of dust aerosols in the climate system. However, it is a difficult task to attribute the airborne dust over the remote land and ocean regions to their origins since dust from various sources are mixed during long‐range transport. Recently, a multi‐model experiment, namely the AeroCom‐III Dust Source Attribution (DUSA), has been conducted to estimate the relative contribution of dust in various locations from different sources with tagged simulations from seven participating global models. The BASE run and a series of runs with nine tagged regions were made to estimate the contribution of dust emitted in East‐ and West‐Africa, Middle East, Central‐ and East‐Asia, North America, the Southern Hemisphere, and the prominent dust hot spots of the Bodélé and Taklimakan Deserts. The models generally agree in large scale mean dust distributions, however models show large diversity in dust source attribution. The inter‐model differences are significant with the global model dust diversity in 30%–50%, but the differences in regional and seasonal scales are even larger. The multi‐model analysis estimates that North Africa contributes 60% of global atmospheric dust loading, followed by Middle East and Central Asia sources (24%). Southern hemispheric sources account for 10% of global dust loading, however it contributes more than 70% of dust over the Southern Hemisphere. The study provides quantitative estimates of the impact of dust emitted from different source regions on the globe and various receptor regions including remote land, ocean, and the polar regions synthesized from the seven models. Plain Language Summary: As the most abundant aerosol type in the Earth's atmosphere, mineral dust plays an important role in global climate by interacting with incoming and outgoing radiation, providing liquid and ice cloud nuclei, and affecting atmospheric stability. The global dust sources are relatively well characterized by the remote sensing and modeling studies as the majority of dust is emitted from the so‐called dust belt which expands from North Africa to East Asia. However, it is challenging to attribute dust sources over the remote land and ocean regions, since dust is mixed during long‐range transport, where it experiences complex atmospheric processes, including horizontal and vertical‐advection, wet deposition, and dry deposition. Using the multi‐model simulations in the Aerocom/Dust Source Attribution experiment, the present study (a) examines the model diversity in dust source attribution and (b) estimates the contribution of dust sources to various receptor regions, including remote land/ocean and the polar regions in different altitudes, from the multi‐model statistics. Beyond dust sources, many remote land, ocean, and polar regions are affected by a mixture of dust from various sources around the globe. Key Points: Contributions of various dust sources are quantitatively estimated in a multi‐model experimentContributions of various sources have different horizontal and vertical distributions and seasonalityDust near source regions are dominated by dust emitted in the upwind source regions; however many remote land, ocean, and polar regions are affected by a mixture of dust from various sources around the globe [ABSTRACT FROM AUTHOR]

The Geostationary Environment Monitoring Spectrometer (GEMS) is the world's first ultraviolet–visible instrument for air quality monitoring in geostationary orbit. Since its launch in 2020, GEMS has provided hourly daytime air quality information over Asia. However, to date, validation and applications of these data are lacking. Here we evaluate the effectiveness of the first 1.5-year GEMS aerosol optical depth (AOD) data in estimating ground-level particulate matter (PM) concentrations at an hourly scale. To do so, we employ random forest models and use GEMS AOD data and meteorological variables as input features to estimate PM10 and PM2.5 concentrations, respectively, in South Korea. The model-estimated PM concentrations are strongly correlated with ground measurements, but they exhibit negative biases, particularly during high aerosol loading months. Our results indicate that GEMS AOD values represent underestimates compared to ground-measured AOD values, possibly leading to negative biases in the final PM estimates. Further, we demonstrate that more training data could significantly improve random forest model performance, thus indicating the potential of GEMS for high-resolution surface PM prediction when sufficient data are accumulated over the coming years. Our results will serve as a reference to aid the evaluation of future GEMS AOD retrieval algorithm improvements and also provide initial guidance for data users. [ABSTRACT FROM AUTHOR]

We report on a method of measuring the stiffness in photophoretic force tweezers in air by using an experimental configuration with two counter-propagating hollow beams. By setting the optical traps of both beams in the same focal plane of the camera, we are able to record the flight procedure of a trapped particle into the other trap after the initial trapping beam is switched off. Then, the stiffness of optical trap can be obtained by fitting the relationship of particle position vs time during the flight procedure. It is found that the measurement is tolerant to the distance between the traps and laser power variation. In addition, the measured stiffness is demonstrated applicable in determining the size of aerosol particles. The reliable method provided in this work is not only useful in studying the physical behavior of signal particle under atmosphere condition but also meaningful in the applications of aerosol studies, such as in situ aerosol characterization and the local surrounding environment sensing. [ABSTRACT FROM AUTHOR]

The article presents the correction for a article titled "Towards reliable retrievals of cloud droplet number for non-precipitating planetary boundary layer clouds and their susceptibility to aerosol" published on August 12, 2024.

Remote sensing has been a key resource for developing extensive and detailed datasets for studying and constraining aerosol-cloud-climate interactions. However, aerosol-cloud collocation challenges, algorithm limitations, as well as difficulties in unraveling dynamic from aerosol-related effects on cloud microphysics, have long challenged precise retrievals of cloud droplet number concentrations. By combining a series of remote sensing techniques and in situ measurements at ground level, we developed a semiautomated approach that can address several retrieval issues for a robust estimation of cloud droplet number for non-precipitating Planetary Boundary Layer (PBL) clouds. The approach is based on satellite retrievals of the PBL cloud droplet number (Ndsat) using the geostationary meteorological satellite data of the Optimal Cloud Analysis (OCA) product, which is obtained by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) of the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT). The parameters of the retrieval are optimized through closure with droplet number obtained from a combination of ground-based remote sensing data and in situ observations at ground level. More specifically, the remote sensing data are used to retrieve cloud-scale vertical velocity, and the in situ aerosol measurements at ground level were used constrain as input to a state-of-the-art droplet activation parameterization to predict the respective Cloud Condensation Nuclei (CCN) spectra, cloud maximum supersaturation and droplet number concentration (Nd), accounting for the effects of vertical velocity distribution and lateral entrainment. Closure studies between collocated Nd and Nd sat are then used to evaluate exising droplet spectral width parameters used for the retrieval of droplet number, and determine the optimal values for retrieval. This methodology, used to study aerosol-cloud interactions for non-precipitating clouds formed over the Athens Metropolitan Area (AMA), Greece, during the springtime period from March to May 2020, shows that droplet closure can be achieved to within ±33.4%, comparable to the level of closure obtained in many in situ studies. Given this, the ease of applying this approach with satellite data obtained from SEVIRI with high temporal (15 min) and spatial resolution (3.6 km Ã--4.6 km), opens the possibility of continuous and reliable Ndsat, giving rise to high value datasets for aerosol-cloud-climate interaction studies. [ABSTRACT FROM AUTHOR]

Previous studies have shown that aerosols invigorate deep convective systems (DCS). However, the magnitude or even the existence of aerosol invigoration of DCS remains controversial. Here, we aimed to observationally quantify the full aerosol effects on DCS by tracking their entire lifecycle and spatial extent in tropical regions. We found that fine aerosols (FA) can invigorate DCS, making them taller and longer lived, and resulting in up to ×5 increase in total area and rainfall amount. In contrast, added coarse sea salt aerosols (CSA) over the ocean can inhibit the vertical development of DCS through enhancing warm rain formation, yet resulting in longer lived and extensive DCSs. Notably, combining FA and CSA generates the strongest aerosol invigoration effect at the concentrations of ~5 and ~80 μg/m³, leading up to ×10 increase in rainfall amount. Our results indicate that aerosols significantly redistribute convective precipitation and climate effects, greatly underestimated in previous studies. [ABSTRACT FROM AUTHOR]

Utilizing a computed tomography (CT)‐based realistic nasal‐to‐lung respiratory tract model allows for a comprehensive investigation of the transport and deposition of nasal sprayed aerosols. This study has three main objectives: first, to determine the optimal mesh that achieves the quickest convergence for computational fluid‐particle dynamics (CFPD) simulations of a nasal‐to‐lung nasal respiratory tract by assessing the performance of different element types, sizes, and prism boundary layers; second, to design and validate a numerical method to compare grid data with different mesh structures and densities for simulation result validation; and finally, to observe and analyze fluid‐particle dynamics in the respiratory tract to aid in the development of nasal sprayed medications. This study involves reverse‐engineering a realistic and anatomically accurate respiratory tract model from CT scans. Results reveal that the optimal numerical approach for minimum calculation time is the polyhedral hybrid mesh with four boundary prism layers and the SIMPLE pressure‐velocity coupling scheme. Furthermore, observations of particle dynamics reveal that the vocal cords' location contains a concentration site of deposited small aerosols due to the turbulent airflow in the region. The optimal diameters of nasal sprayed aerosols to target each region are concluded in the end. [ABSTRACT FROM AUTHOR]

This study introduces a laser scattering system to protect a low-speed aircraft. Scattering was selected to reduce the laser's intensity targeting the sensor of an aircraft and simultaneously maintaining the functionality of aircraft optics. Mie scattering, known for effectively decreasing short-wave infrared light, was employed by utilizing water aerosols having a diameter of 1 to 5 μm. Experimental results regarding the decrease of the laser intensity via scattering confirmed that the theoretical and experimental values resulted in a similar decrease rate under static conditions. To validate the theoretical values, the path length, which the laser passing through water aerosols, was changed. To assess the system's feasibility in flow conditions, a low-speed wind tunnel was employed to generate two flow speeds: 5.5 m/s and 17.6 m/s. Remarkably, the reduction of laser intensity was only affected by the path length, and was somewhat unaffected regardless of flow speed and the uniformity of the flow, only to the path length. In all cases, the initial laser intensity was set to 10 mW. Under static conditions, the intensity dropped to 8.21 mW, showing a decrease of 17.9%. In flow conditions of 5.5 m/s, 17.6 m/s, and in distorted flow, the laser intensity decreased by 18.3%, 18.1%, and 18% respectively. As a preliminary study, these results demonstrate the system's capability to protect a low-speed aircraft targeted by lasers even under dynamic flow conditions, may suggest a possibility of providing a practical defence solution. [ABSTRACT FROM AUTHOR]

We provide an extensive review of 14 studies (11 independent and three industryfunded) on emissions generated by Electronic Cigarettes (ECs), specifically focusing on the evaluation of carbonyls present in these emissions and emphasizing a meticulous evaluation of their analytical methods and experimental procedures. Since the presence of carbonyl by-products in EC aerosol is concerning, it is important to evaluate the reliability of emission studies quantifying these compounds by verifying their compliance with the following criteria of experimental quality: authors must 1) supply sufficient information on the devices and experimental procedures to allow for potentially reproducing or replicating the experiments, 2) use of appropriate puffing protocols that approach consumer usage as best as possible, 3) use of appropriate analytical methods and 4) usage of blank samples to avoid false positive detection. Outcomes were classified in terms of the fulfilment of these conditions as reliable in seven studies, partially reliable in five studies, and unreliable in two studies. However, only five studies used blank samples and six studies failed the reproducibility criterion. Carbonyl yields were far below their yields in tobacco smoke in all reproducible studies, even in the partially reliable ones, thus supporting the role of ECs (when properly tested and operated) as harm reduction products. This review highlights the necessity to evaluate the quality of laboratory standards in testing EC emissions to achieve an objective assessment of the risk profile of ECs. [ABSTRACT FROM AUTHOR]

As the health impact of ultrafine particles is getting better understood, modelling the size distribution and the number concentration with chemistry transport models becomes an increasingly important matter. The number concentrations is strongly affected by processes linked to aerosol dynamics: coagulation, condensation and gas/particle phase partitioning, nucleation. Coagulation is usually solved using an Eulerian approach, using a fixed diameter size discretization. In opposition, condensation/evaporation is rather solved using a Lagrangian approach, requiring redistribution of particles on the fixed grid size. Here, a new analytic formulation is presented to compute efficiently coagulation partition coefficients, allowing to dynamically adjust the discretization of the coagulation operator to the Lagrangian size mesh evolution, and therefore solve all the processes linked to aerosol dynamics with a Lagrangian approach, avoiding the redistribution on the fixed size grid. This new approach has the advantage of reducing the numerical diffusion introduced by condensation. The significance of these effects on number concentrations is assessed over Greater Paris with the chemistry transport model Polyphemus/Polair3D coupled to the aerosol model SSH-aerosol, using different size resolution of the particle distribution. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) and their composites have garnered significant attention in recent years due to their exceptional properties and diverse applications across various fields. The conventional batch synthesis methods for MOFs and their composites often suffer from challenges such as long reaction times, poor reproducibility, and limited scalability. Continuous flow synthesis has emerged as a promising alternative for overcoming these limitations. In this short review, we discuss the recent advancements, challenges, and future perspectives of continuous flow synthesis in the context of MOFs and their composites. The review delves into a brief overview of the fundamental principles of flow synthesis, highlighting its advantages over batch methods. Key benefits, including precise control over reaction parameters, improved scalability and efficiency, rapid optimization capabilities, enhanced reaction kinetics and mass transfer, and increased safety and environmental sustainability, are addressed. Additionally, the versatility and flexibility of flow synthesis techniques are discussed. The article then explores various flow synthesis methods applicable to MOF and MOF composite production. The techniques covered include continuous flow solvothermal synthesis, mechanochemical synthesis, microwave and ultrasound-assisted flow synthesis, microfluidic droplet synthesis, and aerosol synthesis. Notably, the combination of flow chemistry and aerosol synthesis with real-time characterization is also addressed. Furthermore, the impact of flow synthesis on the properties and performance of MOFs is explored. Finally, the review discusses current challenges and future perspectives in the field of continuous flow MOF synthesis, paving the way for further development and broader application of this promising technique. [ABSTRACT FROM AUTHOR]

Background: Tuberculosis (TB), a major cause of disease and antimicrobial resistance, is spread via aerosols. Aerosols have diagnostic potential and airborne-microbes other than Mycobacterium tuberculosis complex (MTBC) may influence transmission. We evaluated whether PneumoniaCheck (PMC), a commercial aerosol collection device, captures MTBC and the aeromicrobiome of people with TB. Methods: PMC was done in sputum culture-positive people (≥ 30 forced coughs each, n = 16) pre-treatment and PMC air reservoir (bag, corresponding to upper airways) and filter (lower airways) washes underwent Xpert MTB/RIF Ultra (Ultra) and 16S rRNA gene sequencing (sequencing also done on sputum). In a subset (n = 6), PMC microbiota (bag, filter) was compared to oral washes and bronchoalveolar lavage fluid (BALF). Findings: 54% (7/13) bags and 46% (6/14) filters were Ultra-positive. Sequencing read counts and microbial diversity did not differ across bags, filters, and sputum. However, microbial composition in bags (Sphingobium-, Corynebacterium-, Novosphingobium-enriched) and filters (Mycobacterium-, Sphingobium-, Corynebacterium-enriched) each differed vs. sputum. Furthermore, sequencing only detected Mycobacterium in bags and filters but not sputum. In the subset, bag and filter microbial diversity did not differ vs. oral washes or BALF but microbial composition differed. Bags vs. BALF were Sphingobium-enriched and Mycobacterium-, Streptococcus-, and Anaerosinus-depleted (Anaerosinus also depleted in filters vs. BALF). Compared to BALF, none of the aerosol-enriched taxa were enriched in oral washes or sputum. Interpretation: PMC captures aerosols with Ultra-detectable MTBC and MTBC is more detectable in aerosols than sputum by sequencing. The aeromicrobiome is distinct from sputum, oral washes and BALF and contains differentially-enriched lower respiratory tract microbes. [ABSTRACT FROM AUTHOR]

This study explores aerosol direct, indirect, and feedback effects on meteorology and fine particulate matter during heat waves of August 2022 over eastern China by using an online coupled regional climate–chemistry–aerosol model. In this period, aerosols exerted mean direct (DRE) and indirect (IRE) radiative effects of −3.9 Wm−2 and −2.4 Wm−2 at TOA, which totally caused a decrease in average surface air temperature by 0.3 °C over east China, accompanied by decreases in PBLH (planetary boundary layer height) and precipitation and an increase in PM2.5 concentration. With the anthropogenic emission reduction from 2013 to 2022, DRE apparently decreased while IRE changed little, leading to a decrease in total aerosol radiative effect (TRE) by 27% at TOA. The weakened TRE resulted in increases in surface air temperature and precipitation by 0.14 °C and 2.7 mm, respectively, on average over east China, with the maximum warming exceeding 0.5 °C in BTH (Beijing–Tianjin–Hebei province). This study highlights a warming trend due to weakened TRE, which may exacerbate heat wave, and an increasing importance of aerosol IRE relative to DRE due to weak sensitivity of cloud properties to aerosol change during the emission reduction. [ABSTRACT FROM AUTHOR]

Ships brighten low marine clouds from emissions of sulfur and aerosols, resulting in visible "ship tracks". In 2020, new shipping regulations mandated an ∼80% reduction in the allowed fuel sulfur content. Recent observations indicate that visible ship tracks have decreased. Model simulations indicate that since 2020 shipping regulations have induced a net radiative forcing of +0.12 Wm−2. Analysis of recent temperature anomalies indicates Northern Hemisphere surface temperature anomalies in 2022–2023 are correlated with observed cloud radiative forcing and the cloud radiative forcing is spatially correlated with the simulated radiative forcing from the 2020 shipping emission changes. Shipping emissions changes could be accelerating global warming. To better constrain these estimates, better access to ship position data and understanding of ship aerosol emissions are needed. Understanding the risks and benefits of emissions reductions and the difficultly in robust attribution highlights the large uncertainty in attributing proposed deliberate climate intervention. Plain Language Summary: Ships have a unique climate effect due to brightening of low marine clouds, resulting in visible "ship tracks". These ship tracks are due to clouds interacting with ship emissions, particularly sulfur. Recently, regulations have drastically reduced allowable ship sulfur emissions. This has resulted in a decrease in observable ship tracks. Modeling and observations indicate that the reduction in ship sulfur emissions could have slightly warmed the planet starting in 2020. These changes are remarkably co‐incident with observed patterns of cloud changes and may have accelerated global warming. Key Points: Recent regulations on ship sulfur emissions have decreased ship tracks and resulted in +0.12 Wm−2 of radiative forcingObserved cloud anomalies are correlated with observed ocean temperature anomalies and shipping radiative forcingReduced ship emissions may have accelerated global warming contributing to recent warm Northern Hemisphere surface temperatures [ABSTRACT FROM AUTHOR]

In August 2017, a smoke plume from wildfires in British Columbia and the Northwest Territories recirculated and persisted over northern Canada for over two weeks. We compared a full‐factorial set of NASA Goddard Institute for Space Studies ModelE simulations of the plume to satellite retrievals of aerosol optical depth and carbon monoxide, finding that ModelE performance was dependent on the model configuration, and more so on the choice of injection height approach, aerosol scheme and biomass burning emissions estimates than to the choice of horizontal winds for nudging. In particular, ModelE simulations with free‐tropospheric smoke injection, a mass‐based aerosol scheme and comparatively high fire NOx emissions led to unrealistically high aerosol optical depth. Using paired simulations with and without fire emissions, we estimated that for 16 days over an 850,000 km2 region, the smoke decreased planetary boundary layer heights by between 253 and 547 m, decreased downward shortwave radiation by between 52 and 172 Wm−2, and decreased surface temperature by between 1.5°C and 4.9°C, the latter spanning an independent estimate from operational weather forecasts of a 3.7°C cooling. The strongest surface climate effects were for ModelE configurations with more detailed aerosol microphysics that led to a stronger first indirect effect. Plain Language Summary: Smoke from biomass burning is known to have effects on surface weather. We used the NASA GISS ModelE to estimate these effects for a large 2017 smoke plume over northern Canada that persisted for two weeks. We first found that the height of the smoke release at the source was the most important factor influencing agreement between ModelE and satellite retrievals of aerosols and carbon monoxide, and that specific, plausible configurations of the model led to unrealistically high aerosol amounts. By comparing simulations with and without fire, we estimated a 16‐day cooling over a 850,000 km2 region of between 1.5°C and 4.9°C, depending on the model configuration. Key Points: We captured the overall pattern and magnitude of a large 2017 smoke plume over Canada with the NASA GISS ModelEOf the sixteen plausible model configurations tested under a full‐factorial design, two with higher NOx emissions, free‐tropospheric smoke release and mass‐based aerosols led to unrealistically high aerosol optical depthOver an 850,000 km2 region, we estimated a 16‐day surface cooling of between 1.5°C and 4.9°C [ABSTRACT FROM AUTHOR]

Satellite remote sensing of aerosol is largely conducted at moderate or coarse spatial resolution around 1–10 km. Nevertheless, at urban areas with high human activity, aerosol can originate from complex emission sources and may also vary strongly in space. Therefore, aerosol characterization at fine spatial resolution is essential for air quality study and assessment of anthropogenic pollution as well as climate effects. However, space‐borne instruments with high spatial resolution are usually limited in swath width or spectral coverage which result in lowering information content required for aerosol and surface retrieval. Based on the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm, we propose a hybrid approach by combining fine and coarse spatial resolution measurements to retrieve aerosol and surface properties simulataneously at fine spatial resolution. The instruments with coarse spatial resolution and high revisting time can provide advanced aerosol characterization. At the same time, the instruments with fine spatial resolution are sensitive to spatial variability of aerosol nearby sources. In this study, the GRASP/Hybrid approach is demonstrated and tested based on the European Space Agency Sentinel‐5p/TROPOMI together with the Italian Space Agency PRISMA satellite data. Specifically, the detailed aerosol microphysical properties from Sentinel‐5p/TROPOMI 10 km retrievals are used as a priori information for PRISMA to derive aerosol loading and surface properties at 100 meter (m) spatial resolution. The PRISMA 100 m aerosol and surface retrieval based on the developed GRASP/Hybrid approach are evaluated using available ground‐based and satellite measurements, including AERONET, VIIRS/DB aerosol and PRISMA Level 2 surface reflectance products. Plain Language Summary: Both aerosol and surface characterization at high spatial resolution are always highly demanded especially over densely populated urban areas. However, the high spatial resolution space‐borne instruments typically have small swaths that, in general, reduce the possibility of aerosol and surface decoupling. In this paper, we develop a hybrid approach based on GRASP algorithm (GRASP/Hybrid) to retrieve aerosol and surface properties at fine spatial granularity by combining fine and coarse spatial resolution satellite data. The GRASP/Hybrid approach is demonstrated using European Space Agency (ESA) Sentinel‐5p/TROPOMI and Italian Space Agency (ASI) PRISMA (Hyperspectral Precursor of the Application Mission) measurements. Specifically, the detailed aerosol microphysical properties from Sentinel‐5p/TROPOMI 10 km retrievals are used as a priori information to derive aerosol loading and surface properties exploiting PRISMA at 100 m spatial resolution. Overall, the results obtained in this study demonstrate the big potential of the approach based on the combination of instruments for a number of climate and environment monitoring studies. Key Points: Generalized Retrieval of Atmosphere and Surface Properties (GRASP)/Hybrid approach is developed and demonstrated using Sentinel‐5p/TROPOMI and PRISMA measurementsPRISMA 100 m aerosol and surface properties are retrieved based on GRASP/Hybrid approach and evaluated using reference data setsWe demonstrate the big potential of hybrid approach based on the combination of instruments for climate and environment studies [ABSTRACT FROM AUTHOR]

Assessing aerosol mixing states, which primarily depend on aerosol chemical compositions, is indispensable to estimate direct and indirect effects of aerosols. The limitations of the direct measurements of aerosol chemical composition and mixing states necessitate modeling approaches to infer the aerosol mixing states. The Optical Properties of Aerosols and Clouds (OPAC) model has been extensively utilized to construct optically equivalent aerosol chemical compositions from measured aerosol optical properties using Mie inversion. However, the representation of real atmospheric aerosol mixing scenarios in OPAC has perennially been challenged by the exclusive assumption of external mixing. A Python successor to the aerosol module of the OPAC model is developed, named AeroMix, with novel capabilities to (1) model externally and core–shell mixed aerosols, (2) simulate optical properties of aerosol mixtures constituted by any number of aerosol components, and (3) define aerosol composition and relative humidity in up to six vertical layers. Designed as a versatile open-source aerosol optical model framework, AeroMix is tailored for sophisticated inversion algorithms aimed at modeling aerosol mixing states and also their physical and chemical properties. AeroMix's performance is demonstrated by modeling the probable aerosol mixing states over Kanpur (urban) and the Bay of Bengal (marine) in south Asia. The modeled mixing states are consistent with independent measurements using a single-particle soot photometer (SP2) and transmission electron microscopy (TEM), substantiating the potential capability of AeroMix to model complex aerosol mixing scenarios involving multiple internally mixed components in diverse environments. This work contributes a valuable tool for modeling aerosol mixing states to assess their impact on cloud-nucleating properties and radiation budget. [ABSTRACT FROM AUTHOR]

Long-term ground-based lidar observations are important in estimating the contribution of different sources (mostly volcanic eruptions and wildfires) to aerosol loading of the atmosphere and in developing and improving various climate models. In this paper, we carefully analyse aerosol scattering ratio profiles and aerosol layers, observed with 532-nm lidar measurements at the Siberian Lidar Station in Tomsk (56.48°N, 85.05°E) over the period 2018–2022, and identify the layers' potential sources. To compare aerosol loading over Tomsk for the last five years (2018–2022) with that for previous years, we also present and discuss time series of integrated aerosol backscatter coefficient (IABC) for three altitude ranges. The first range (15–30 km) reveals the pure stratospheric aerosol loading provided by volcanic eruptions, the second range (11–15 km) is responsible mainly for aftereffects of wildfire smoke plumes, and the third one (11–30 km) demonstrates aerosol contribution from both sources. In particular, we found for the period 2001–2022 that the annual average IABC reached its maximal values of 2.91 × 10−4 sr−1 (15–30 km) and 8.21 × 10−4 sr−1 (11–30 km) in 2022 due to the Hunga Tonga-Hunga Ha'apai volcanic eruption. The period 2020–2022 exhibited a significant increase in the relative aerosol content at altitudes of 11–15 km in the total aerosol loading at 11–30 km over Tomsk from 54.4% in 2020 to 64.8% in 2022, which indicates a shift of the main part of aerosol loading to altitudes of 11–15 km due to the increased wildfire activity in North America and north-eastern Asia. The Arctic polar vortex is also revealed to distort the real aerosol vertical distribution over Tomsk by replacing it with the aerosol distribution inside the vortex on measurement days when the vortex is over the lidar site. [ABSTRACT FROM AUTHOR]

The Advanced Geostationary Radiation Imager (AGRI) sensor on board the geostationary satellite Fengyun-4B (FY-4B) is capable of capturing particles in different phases in the atmospheric environment and acquiring aerosol observation data with high spatial and temporal resolution. To understand the quality of the Land Aerosol (LDA) product of AGRI and its application prospects, we conducted a comprehensive evaluation of the AGRI LDA AOD. Using the 550 nm AGRI LDA AOD (550 nm) of nearly 1 year (1 October 2022 to 30 September 2023) to compare with the Aerosol Robotic Network (AERONET), MODIS MAIAC, and Himawari-9/AHI AODs. Results show the erratic algorithmic performance of AGRI LDA AOD, the correlation coefficient (R), mean error (Bias), root mean square error (RMSE), and the percentage of data with errors falling within the expected error envelope of ± (0.05 + 0.15 × AOD A E R O N E T) (within EE15) of the LDA AOD dataset are 0.55, 0.328, 0.533, and 34%, respectively. The LDA AOD appears to be overestimated easily in the southern and western regions of China and performs poorly in the offshore areas, with an R of 0.43, a Bias of 0.334, a larger RMSE of 0.597, and a global climate observing system fraction (GCOSF) percentage of 15% compared to the inland areas (R = 0.60, Bias = 0.163, RMSE = 0.509, GCOSF = 17%). Future improvements should focus on surface reflectance calculation, water vapor attenuation, and more suitable aerosol model selection to improve the algorithm's accuracy. [ABSTRACT FROM AUTHOR]

Secondhand vaping exposure is an emerging public health concern that remains understudied. In this study, saliva and exhaled emissions from ENDS users (secondhand) and non-ENDS users (baseline) were collected, firsthand emissions were generated using an automated ENDS aerosol generation system programmed to simulate puffing topography profiles collected from ENDS users. Particulate concentrations and sizes along with volatile organic compounds were characterized. We revealed puffing topography metrics as potential mediators of firsthand and secondhand particle and chemical exposures, as well as metabolic and respiratory health outcomes. Particle deposition modeling revealed that while secondhand emissions displayed smaller deposited mass, total and pulmonary particle deposition fractions were higher than firsthand deposition levels, possibly due to smaller secondhand emission particle diameters. Lastly, untargeted metabolomic profiling of salivary biomarkers of lung injury due to firsthand ENDS exposures revealed potential early indicators of respiratory distress that may also be relevant in bystanders exposed to secondhand vaping scenarios. By leveraging system toxicology, we identified 10 metabolites, including leukotriene D4, that could potentially serve as biomarkers for ENDS use, exposure estimation, and the prediction of vaping-related disease. This study highlights characterization of vaping behavior is an important exposure component in advancing our understanding of potential health effects in ENDS users and bystanders. [ABSTRACT FROM AUTHOR]

This study presents the hygroscopic properties of aerosols from the Arctic free troposphere by means of contemporary lidar and radiosonde observations only. It investigates the period from the Arctic Haze in spring towards the summer season in 2021. Therefore, a one-parameter growth curve model is applied to lidar data from the Koldewey Aerosol Raman Lidar (AWIPEV in Ny-Ålesund, Svalbard) and simultaneous radiosonde measurements. Hygroscopic growth depends on different factors like aerosol diameter and chemical composition. To detangle this dependency, three trends in hygroscopicity are additionally investigated by classifying the aerosol first by its dry color ratio, and then by its season and altitude. Generally, we found a complex altitude dependence with the least hygroscopic particles in the middle of the troposphere. The most hygroscopic aerosol is located in the upper free troposphere. A hypothesis based on prior lifting of the particles is given. The expected trend with aerosol diameter is not observed, which draws attention to the complex dependence of hygroscopic growth on geographical region and altitude, and to the development of backscatter with the aerosol size itself. In a seasonal overview, two different modes of stronger or weaker hygroscopic particles are additionally observed. Furthermore, two special days are discussed using the Mie theory. They show, on the one hand, the complexity of analyzing hygroscopic growth by means of lidar data, but on the other hand, they demonstrate that it is in fact measurable with this approach. For these two case studies, we calculated that the aerosol effective radius increased from 0.16 μ m (dry) to 0.18 μ m (wet) and from 0.28 μ m to 0.32 μ m for the second case. [ABSTRACT FROM AUTHOR]

Recently, in China, during the period of transition between spring and summer, the combination of sandstorms and ozone (O3) pollution has posed a significant challenge to the strategy of coordinated control of fine particulate matters (PM2.5) and O3. On the one hand, the dust invasion brings many primary aerosols and causes a large range of transboundary transport. On the other hand, the high concentration of aerosol causes a severe disturbance to the distribution of O3. Traditionally, high-resolution assessments of the spatial distribution of aerosols and O3 can be carried out using LiDAR technology. However, the negligence of the influence of aerosols in the process of O3 retrieval in traditional differential absorption lidar (DIAL) leads to an error in the accuracy of ozone concentration. Especially when dust transit occurs, the errors become bigger. In this study, a self-customized four-wavelength differential-absorption LiDAR system was used to synchronously obtain the accurate vertical distributions of ozone and high-concentration aerosol. The wavelength index of concentrated aerosol was inverted and applied to the differential equation framework for O3 calculation. This novel approach to retrieving the vertical profile of O3 was proposed and verified by applying it to a dust pollution event that occurred from April to May 2021 in Anyang City Henan Province, which is located in Northern China. It was found that the extinction coefficient of aerosol reached 2.5 km−1 during the dust period, and O3 was mainly distributed between 500 m and 1500 m. The O3 error exceeded over 10% arising from the high-concentration aerosol below 1.5 km during the dust storm event. By employing the inversion algorithm while considering the aerosol effects, the ozone concentration error was improved by over 10% compared with the error recorded without considering the aerosol influence especially in dust events. Through this study, it was found that the algorithm could effectively realize the synchronous and accurate inversion of high-concentration aerosols and O3 and can provide key technical support for air pollution control in China in the future. [ABSTRACT FROM AUTHOR]

Particulate organic nitrates (pON) significantly contribute to the mass of organic aerosol and influence the nitrogen oxides cycle in the atmosphere, but their evolution and lifetime remain uncertain. This study performed simultaneous measurements on the anthropogenically affected surface site and the mountain site on top of the polluted planetary boundary layer (PBL). After aging in the PBL, organic nitrate was converted from primary sources (decreased from 8.7% to 4.3%) to secondary sources (increased from 6.3% to 36.1%), spanning from the surface to the mountain. The evaporation of more volatile inorganic nitrate and the production of secondary organic nitrate during aging in the PBL contributed to the enhanced pON fraction over the top of PBL. The contribution of light absorption by brown carbon increased by 57% at the top of PBL compared to the surface, consistent with the higher fraction of nitrogenous organic aerosols over the mountain. The results provide field evidence that the nitrogenous organic aerosols (OA) may be preserved by adding into secondary OA and significantly contribute to the enhanced importance of brown carbon after aging during vertical transport in the PBL. [ABSTRACT FROM AUTHOR]

Climate models commonly overestimate warm rain frequency and underestimate its intensity over the ocean, primarily due to insufficient representation of the aerosol effects. This pertains to both fine aerosols (FA) and coarse sea spray aerosols (CSA), where the latter is mostly absent in the models. Here, our observations show that adding CSA enhances vertical warm rain structure, in contrast to the effect of FA. The magnitude of the effect of CSA is larger than the opposite effect of the FA. For rain with top heights of 2–3 km, the raindrop size, concentration, and rain rate can be increased by factors of 1.03, 1.47, and 1.60, respectively. These CSA-induced changes are larger for thicker clouds, reaching a maximum by factors of 1.12, 1.85, and 2.21, respectively. Therefore, the combined FA and CSA effects should be incorporated into climate models for accurately simulated precipitation microphysical processes. [ABSTRACT FROM AUTHOR]

The Southern Ocean (SO) provides a unique natural laboratory for studying cloud formation and cloud-aerosol interactions with minimal anthropogenic influence. The Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES), was an aircraft-based campaign conducted from January 15 to February 28, 2018, off the coast of Hobart, Tasmania. During SOCRATES, the NSF/NCAR GV research aircraft, equipped with in-situ probes and remote sensors, observed aerosol, cloud, and precipitation properties, and provided detailed vertical structure of clouds over the SO, particularly for the low-level clouds (below 3 km). The HIAPER Cloud Radar (HCR) and in-situ cloud and drizzle probes (CDP and 2DS) measurements were used to provide comprehensive statistical and phase-relevant macrophysical properties for the low-level clouds sampled by the 15 research flights during SOCRATES. A new method based on HCR reflectivity and spectrum width gradient was developed to estimate cloud boundaries (cloud-base and -top heights) and classify cloud types based on their top and base heights. Low-level clouds were found to be the most prevalent, with an almost 90 % occurrence frequency. A new phase determination method was also developed to identify the single-layered low-level clouds as liquid, ice, and mixed phases, with occurrence frequencies of 45.4 %, 32.5 %, and 22.2 %, respectively. Low-level clouds over the SO have significantly higher SLW concentrations, with liquid being most prevalent at higher temperatures, ice phase dominating at lower temperatures, and mixed-phase being least common due to its thermodynamic instability. Regarding their vertical distributions, the liquid phase occurs most frequently in the lower mid-cloud range (from 500 m to 1 km), the mixed phase dominates at cloud bases lower than 1 km but is well distributed along the vertical cloud layer, while the ice phase is prevalent from the middle to upper cloud levels (1–3 km). The higher occurrence of the mixed phase at the cloud base could be attributed to large drizzle-sized drops and/or ice particles. [ABSTRACT FROM AUTHOR]

We develop the Japan Aerospace Exploration Agency (JAXA) level 2 cloud mask and cloud type classification algorithms for the Earth Clouds, Aerosols, and Radiation Explorer (EarthCARE), a joint JAXA and European Space Agency (ESA) satellite mission. Cloud profiling radar (CPR)-only, atmospheric lidar (ATLID)-only, and combined CPR–ATLID algorithms for the cloud mask and cloud particle type are described. The algorithms are developed and evaluated using ground-based data, space-borne data from CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and simulation data from a Japanese global cloud-resolving model, the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) with Joint simulator. The algorithms are based on our algorithms for CloudSat and CALIPSO with several improvements. The cloud particle type for ATLID is derived from an attenuation–depolarization diagram trained using 355 nm multiple-field-of-view multiple-scattering polarization lidar and changing the diagram from that developed for CALIPSO. The retrieved cloud particle phases (ice, water, and mixed phases) and those reported in the NICAM output data are compared. We found that the agreement for CPR-only, ATLID-only, and combined CPR–ATLID algorithms averaged roughly 80 %, 85 %, and 80 %, respectively, for 15 different cloud scenes corresponding to two EarthCARE orbits. [ABSTRACT FROM AUTHOR]

The contents of water-soluble major's ions (MSA, Cl−, NO3−, SO42−, Na+, NH4+, K+, Mg2+, and Ca2+) in the PM10 particle fraction were investigated thanks to detailed measurements of the main chemical constituents of PM10 in remote coastal areas in Bou-Ismail; in the South-West of the Mediterranean Sea (Algeria), during a 2-year period; from July 2011 to August 2013, under the framework of the ChArMEx project (Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr). The total water-soluble ion concentrations in PM10 at the Bou-Ismail measurement station varied from 3.3 µg/m3 (July 2011) to 49.6 µg/m3 (March 2012). The annual mean mass concentrations of ions in the PM10 particulate fraction were Cl− > Na+ > SO42− > Mg2+ > NO3− > Ca2+ > K+ > NH4+ > Oxalate. The change in potassium nss-K + concentrations in PM10 over the course of a year reveals that biomass burning (BB) has an effect on three separate seasons: the beginning of winter (February and March), the end of summer (August), and the autumn (September and October). The origin periods of biomass burning BB identified employing the mapping of hotspots and fires during periods of August and September 2011, 2012, and 2013 underlined the important fires in the surrounding areas of the Mediterranean Sea (Sardinia Islands from Italy, Corsica from France). [ABSTRACT FROM AUTHOR]