Journal of Aerosol Science最新文献

{"title":"Non-linear optics for an online probing of the specific surface area of nanoparticles in the aerosol phase","authors":"","doi":"10.1016/j.jaerosci.2024.106484","DOIUrl":"10.1016/j.jaerosci.2024.106484","url":null,"abstract":"<div><div>In the present study the generation of non-linear optical (NLO) effects, such as second harmonic generation (SHG), by black carbon particles, also named soot, and by other types of nanoparticles in aerosol phase is quantified and analysed. Its potential for measuring the specific surface area of an aerosol is put forward. SHG is a Non Linear Optical phenomenon that is typically used in biosciences and fundamental physics and has shown to have large potential for the investigation of surface sensitive phenomena. It exists in two forms, coherent SHG and incoherent SHG, also named Hyper Rayleigh Scattering (HRS). While applications on particles in solution or organic molecules located on the surface of droplets exist, the SHG naturally induced by solid nanoparticles in aerosol phase without any SHG enhancing additive has neither been detected nor quantified yet. The present work aims at narrowing this gap by exposing a jet of well-characterized nanoaerosols to a femtosecond laser featuring high peak pulse energies allowing to induce NLO phenomena. The experiments are carried out in an innovative optical setup allowing to analyse the NLO response resolved in time, wavelength and angle, thus having the capability to isolate SHG from other phenomena, such as laser filamentation. The optical setup was calibrated in order to quantify the generated signal power and optimized in order to have a high sensitivity and in order to avoid NLO generation from its own optical elements. The results confirm that soot particles, as well as DEHS droplets and arc generated carbon nanoparticles, feature SHG at intensities that are more than 7 orders of magnitude smaller than that of static light scattering. SHG depends in particular on aggregate and/or monomer size. On the other hand, SHG induced by soot does not seem to depend on the organic or elementary carbon content. The experiments also show that the detected NLO signal increases linearly with particle surface area, independently of the particle shape or composition. Finally, the angular response of NLO signal is fundamentally different from that of linear scattering. Due to the isotropic nature of the angular response, the observed SHG signal is probably non-coherent and thus related to Hyper Raleigh Scattering. These findings show the potential of non-linear optics, in particular to quantify in situ the specific surface of an aerosol. Giving access to this information which is crucial in the evaluation of toxicity of aerosols, the present work can thus give way to a new class of laser based diagnostics for aerosols.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational and experimental investigation of an aerosol extraction device for use in dentistry","authors":"","doi":"10.1016/j.jaerosci.2024.106478","DOIUrl":"10.1016/j.jaerosci.2024.106478","url":null,"abstract":"<div><div>Medical procedures carry a high risk of pathogen transmission from patients to healthcare providers, the clinic environment, and subsequent patients. While measures such as patient mask wearing can help to reduce this danger, they may not always be possible, especially in dental treatments that need access to patients’ airways. A protective device was designed and built to effectively confine airborne particles during medical procedures without interfering with medical operations. The device is evaluated and its working principles discussed.</div><div>The device resembles a dome and comprises of four primary mechanisms to inhibit the spread of potentially infected aerosols during aerosol-generating procedures (AGPs) in dental surgery: (i) a physical barrier; (ii) air curtains; (iii) an extraction point; (iv) a sustained airflow ingress. Evaluation is carried out using experiments in laboratory and clinical settings, as well as high-resolution numerical simulations.</div><div>Results of the numerical simulations of the prototype device show over 99% capture in its design configuration. The results from experiments also report high efficiency. A detailed analysis of the device and recommendations for future development are provided. The results from tests in the clinical setting will be provided in detail in another paper.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Collision frequencies across collision regimes in two-component systems","authors":"","doi":"10.1016/j.jaerosci.2024.106480","DOIUrl":"10.1016/j.jaerosci.2024.106480","url":null,"abstract":"<div><div>Agglomeration is the most important growth process in particle systems but modelling efforts typically assume mono-disperse primary particle distributions for the closure of the collision frequency that determines the growth rates. Real systems such as sooting flames, however, involve poly-disperse primary particle distributions. Also, systems with multiple components, where primary particles are of distinct but different sizes, cannot be treated as mono-disperse. Here, we introduce bi-disperse primary particle distributions and use Langevin dynamics simulations to develop closures for the collision kernels that are applicable over a wide range of agglomerate characteristics. The simulations cover fractal dimensions from 1.4 to 2.2, primary particle diameters from 5 nm to 50 nm, primary particle size ratios from 2 to 10 and agglomerates of up to a size of 200 primary particles with varying particle compositions. The Langevin dynamics simulations cover all collision regimes from ballistic to diffusive and allow to deduce expressions for the respective collision diameters, the hydrodynamic radii and the projected area as functions of particle characteristics. It is shown that existing expressions for the transition regime that were developed for the modelling of the collision kernel of spherical particles continue to hold for collision kernels of agglomerates in two-component systems under the condition that the collision diameters and drag coefficients are modelled accurately. An example ‘a posteriori’ simulation for a particle size ratio of 6 uses the population balance equation and demonstrates that bi-variate kernels are needed for the accurate prediction of the growth rates. Errors in predicted number density at the end of the simulations are less than 12 % while mono-variate kernels developed for mono-disperse primary particle systems overpredict the growth rate by 46%.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced organic aerosol formation induced by inorganic aerosol formed in laboratory photochemical experiments","authors":"","doi":"10.1016/j.jaerosci.2024.106481","DOIUrl":"10.1016/j.jaerosci.2024.106481","url":null,"abstract":"<div><div>Atmospheric inorganic gases such as NO_x, SO₂, and NH₃ have diverse effects on the formation of secondary organic aerosol (SOA). A comprehensive investigation is necessary to fully understand the atmospheric processing of SOA. In this study, we examined the photooxidation of xylene isomers in the presence of inorganic gases using a combined facility comprising a smog chamber (SC) and an oxidation flow reactor (OFR). SC experiments at higher xylene concentrations and humid conditions revealed SOA yields of 37%, 39%, and 39% with NH₃, compared to 15%, 11%, and 13% without NH₃, for o-, m-, and p-xylene, respectively. This increase was primarily attributed to the enhanced formation of secondary inorganic aerosol (SIA) in the presence of NH₃, consequently increasing aerosol surface area and aerosol water content (AWC). Vapor wall losses (VWL), estimated using a kinetic method, were substantial even with the elevated aerosol surface area provided by SIA. Additional photochemical reactions in the OFR showed a gradual increase in SOA mass and yield over an atmospheric equivalent aging time of 0.5–4.0 days. In the OFR, the SOA yield increased significantly when negligible xylene remained after SC reactions. Fresh SOA formation in the OFR might have decreased the oxygen-to-carbon ratio and oxidation state of carbon, which gradually increased with increasing OFR aging. High OH radical exposure in the OFR likely caused the photodegradation of SC-formed ON, as evidenced by an abrupt decrease in the NO⁺/NO₂⁺ ratio measured. This study indicates that SOA formation potential of the aromatic hydrocarbon is highly underestimated without considering the combined effects of inorganic gases along with aging.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a source-term migration model for a large bubble formed in a core disruptive accident","authors":"","doi":"10.1016/j.jaerosci.2024.106482","DOIUrl":"10.1016/j.jaerosci.2024.106482","url":null,"abstract":"<div><div>Because sodium-cooled fast reactors are designed with high inherent safety in mind, the probability of a core disruptive accident (CDA) is extremely low. However, from a defense-in-depth perspective, the study of CDA sequences is still worthwhile to assure the safety and reliability of reactors. During a CDA, a large bubble rapidly expands inside the sodium pool, rises from the core, and covers the gas region, providing a potential migration path for source terms (radioactive materials present within the containment barriers). Source terms released initially within the cover-gas region after a few hundred milliseconds are called instantaneous source terms. We propose here an instantaneous source-term migration model that provides a simplified evaluation of the amount of source terms absorbed by coolant sodium during the ascent of the CDA bubble. In the model, the particle motion within the CDA bubble obtained from the basic momentum equation is used to calculate the amount of source terms escaping from the bubble interface. In addition, a model analogous to aerosol scavenging by precipitation is used to assess the amount of source terms absorbed by droplets present in the bubble, especially the entrained sodium droplets that form during rapid expansion of the CDA bubble. The model is further validated by a previous source term migration experiment in which a large high-pressure bubble expands and rises in a sodium pool. Good agreement with the measured retention factor of a source term demonstrates the reliability of the developed model. Given these results, some key parameters are selected for a sensitivity analysis.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-stage NBI sampler for PM1 mass and five-stage NBI-NMCI sampler for PM1 mass distribution measurements","authors":"","doi":"10.1016/j.jaerosci.2024.106479","DOIUrl":"10.1016/j.jaerosci.2024.106479","url":null,"abstract":"<div><div>In recent years, concerns about the health and environmental risks associated with PM₁ particles have increased. However, existing PM₁ sampling instruments remain to be improved mainly because their PM₁ inlets have particle loading and bounce issues. To address these challenges, PM₁ inlets based on the Non-Bouncing Impactor (NBI) technique were developed. These inlets employ vacuum oil-wetted glass fiber filter (GFF) substrates to eliminate particle bounce and incorporate a daily vacuum oil injection to prevent particle loading. The 16.7 L/min PM₁ NBI, modified from the PM_2.5 M-WINS design with a reduced diameter of the single nozzle, was designed to adapt readily with current standard sampling and monitoring systems. The cut-size (D_pa50) of 0.99 ± 0.02 μm was determined by considering the effects of Reynold number and the ratio of jet-to-plate distance and nozzle diameter. Field tests comparing the 16.7 L/min PM₁ NBI sampler to the 9-stage NCTU Micro-orifice Cascade Impactor (NMCI₉) revealed small sampling biases, with a mean difference of +0.26 ± 2.28 μg/m³ for PM₁ measurements when silicone oil-coated aluminum foil (AF) and GFF-AF were used in the NMCI₉. The NBI with the oil-wetted GFF substrate effectively removed particles larger than 1.0 μm, resulting in more accurate PM₁ mass concentration measurements. Additionally, the development of a 5-stage NMCI with the 30 L/min PM₁ NBI as the first stage enabled detailed measurement of PM₁ mass distribution in two modes, which was challenging when measuring the entire mass distribution of ambient aerosols. The distribution of size-dependent water-soluble inorganic ions in PM₁ showed dominance of SO₄²⁻ and NH₄⁺ in PM₁ compared to PM_2.5. In summary, the PM₁ NBI enhances accuracy for long-term atmospheric sampling by addressing particle loading and bounce, making it a more reliable standard sampling instrument.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of relative humidity on passive spore release from substrate surfaces","authors":"","doi":"10.1016/j.jaerosci.2024.106477","DOIUrl":"10.1016/j.jaerosci.2024.106477","url":null,"abstract":"<div><div>Fungal spores are abundant in ambient air and exposure to this type of bioaerosols are found to cause significant health and climatic effects. In this study, we investigated the influence of air relative humidity (RH) on the passive release of spores from solid substrates. Preliminary investigations into the effect of RH on fungal spore release indicated an increase in spore flux with reduced air RH. The change in spore emission flux occurred very quickly in response to a change in ambient RH. To verify the hypothesis of extremely rapid drying under lower RH, experiments were conducted using a quartz crystal microbalance with dissipation (QCM-D) to understand the timescales of spore moisture uptake and drying. The analysis of mass transfer of water to and from the spores indicated that the bulk of the transfer occurred within a minute of exposure to any RH. The effect of the ambient RH was explained using a mathematical model with the spotlight on the parameter, E, that represented the energy required to aerosolise one spore. This study demonstrates the application of QCM-D to study interaction between ambient aerosol particles and various vapor phase and gas phase environments. The study enhances the overall understanding and capability to characterise passive fungal spore release under varying humidity conditions in the natural environment.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the potential of in-line particle concentration measurements in gas particle separation processes by using low-cost particulate matter sensors","authors":"","doi":"10.1016/j.jaerosci.2024.106476","DOIUrl":"10.1016/j.jaerosci.2024.106476","url":null,"abstract":"<div><div>In addition to the costly laboratory-based particle measurement devices, low-cost particulate matter sensors for ambient air quality measurements can also be employed for the detection of PM in gas cleaning devices. The ability to spatially resolve the actual level of particle number concentration with high temporal resolution within a gas-particle separation process is of significant value for process monitoring and control. The quantitative reliability of the measurement data from low-cost particulate matter sensors remains uncertain when the particle concentrations in the apparatus exceed the upper measurement limit of the sensors, whether temporarily or permanently. This study examines the potential of low-cost particulate matter sensors for in-line particle concentration measurements in gas-particle separation processes. The measurement performance of the low-cost particulate matter sensors is initially examined under idealised conditions in a dust chamber. This is done in order to quantify the deviations of the low-cost particulate matter sensors in comparison to a state-of-the-art precision laboratory high-cost sensor. Subsequently, both sensor types are installed at a wet separator test facility, following the quantification of their respective measurement performances. The low-cost particulate matter sensors are capable of measuring particle number concentration above their specified limit (up to <span><math><mrow><mo>≈</mo><mtext>6.1</mtext><mo>×</mo><mtext>10</mtext><msup><mrow></mrow><mrow><mi>4</mi></mrow></msup><mspace></mspace><mtext>cm</mtext><msup><mrow></mrow><mrow><mi>−3</mi></mrow></msup></mrow></math></span>), depending on the measurement conditions. By applying a 3rd polynomial correction function, obtained from the initial quantification measurement, the low-cost particulate matter sensors are able to reproduce the particle number concentration measured by the high-cost sensor. Furthermore, the low-cost particulate matter sensors are capable of reproducing short-term fluctuations in the particle number concentration.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of flame stability on iron oxide nanoparticle growth during FSP","authors":"","doi":"10.1016/j.jaerosci.2024.106475","DOIUrl":"10.1016/j.jaerosci.2024.106475","url":null,"abstract":"<div><div>Flame stability during flame spray pyrolysis (FSP) remains an active topic of investigation due to its impact on synthesised particle attributes and purity. The unique feature of the burner investigated here is the ability to control flame stability over newly defined stability maps. The novelty of the current work lies in understanding the influence of these broad stability modes on nanoparticle growth during FSP and on the attributes of collected products. Several distinct flame configurations are selected for iron oxide nanoparticle synthesis, ranging from stable to highly unstable flames. The flame stability regimes are characterised by OH∗ chemiluminescence and broadband flame luminescence imaging. Stability is correlated with the coefficient of variation of flame luminescence (CV) and flame height with mean OH∗ chemiluminescence. Planar Mie scattering is then used to identify the effect of flame luminescence intermittency on spray atomisation and evaporation quality. For particle analysis, in-situ thermophoretic sampling is performed from 30 to 200 mm above the burner exit plane and analysed via transmission electron microscopy (TEM). Further ex-situ analysis is also performed on the bulk-collected product via high-resolution TEM, X-ray powder diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). It is demonstrated that flames with higher instability (CV_min ≥ 0.35) maintain increased spray heights (&gt;26 %) and reduced flame heights (&gt;79 %) compared to stable flames with the same precursor volume flowrate. This reduces the high-temperature particle residence time for primary particle growth and impacts subsequent agglomeration. For example, the mean diameter of gyration and primary particle diameter are found to vary by 44 % and 29 % depending on the flame regime, respectively. Ex-situ analysis also demonstrates that the dominant iron oxide phase produced is maghemite regardless of the stability regime. However, higher concentrations of organic impurities including methyl, methylene and carboxylate functional groups are found via ATR-FTIR with increased flame instability (CV).</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Technical Note: Lifetime of evaporating droplets in a closed volume","authors":"","doi":"10.1016/j.jaerosci.2024.106472","DOIUrl":"10.1016/j.jaerosci.2024.106472","url":null,"abstract":"<div><div>The numerical modeling of heat and mass transfer of droplets within a closed volume containing gas heated in relation to the droplets was conducted. The droplet lifetime at variation of initial values of gas and droplet temperatures and droplet mass fraction has been determined. It was found that droplet lifetime exhibits a weak dependence on the initial droplet temperature and a pronounced dependence on the initial gas temperature. Moreover, it was demonstrated that the droplet lifetime in a closed volume is longer than in infinite space. This is due to the fact that the cooling of the surrounding gas by droplets results in a decrease in the evaporation rate of the droplets. A parameter is proposed which allows for the consideration of the effect of evaporating droplets on the thermal regime of the gas-drop mixture, and which enables the generalization of the results of numerical simulation to obtain an expression for the droplet lifetime in a closed volume. The error in the use of the obtained expression is estimated. It was determined that the margin of error for the calculation results is less than ten percent.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}