Pub Date : 2025-10-03DOI: 10.1016/j.jaerosci.2025.106704
Mingliang Xie , Yixiong Yang
This study investigates the spatially heterogeneous shear-induced coagulation of nanoparticles in a decaying 2D Taylor-Green vortex (TGV) using a novel average kernel method integrated with direct numerical simulation (AK-iDNS). This framework resolves spatially distributed coagulation dynamics, addressing a critical gap in population balance modeling for aerosols. Key features of the approach include: 1) a moment method incorporating localized shear rates from instantaneous velocity gradients; 2) quantitative identification of coagulation-diffusion competition. Simulations reveal a three-stage process: initial uniformity, shear-driven heterogeneity (characterized by depletion in strain sheets and accumulation in vortex cores), and asymptotic re-homogenization driven by diffusion. The asymptotic solution demonstrates self-similar coagulation and exponential dependence on initial shear rate. This work provides a paradigm for predicting nanoparticle evolution in complex vortical flows and establishes a foundation for extending high-precision simulation tools to three-dimensional atmospheric nanoparticle evolution models.
{"title":"Spatially heterogeneous shear-induced coagulation of spherical nano-particles in 2D Taylor-Green vortex using AK-iDNS framework","authors":"Mingliang Xie , Yixiong Yang","doi":"10.1016/j.jaerosci.2025.106704","DOIUrl":"10.1016/j.jaerosci.2025.106704","url":null,"abstract":"<div><div>This study investigates the spatially heterogeneous shear-induced coagulation of nanoparticles in a decaying 2D Taylor-Green vortex (TGV) using a novel average kernel method integrated with direct numerical simulation (AK-iDNS). This framework resolves spatially distributed coagulation dynamics, addressing a critical gap in population balance modeling for aerosols. Key features of the approach include: 1) a moment method incorporating localized shear rates from instantaneous velocity gradients; 2) quantitative identification of coagulation-diffusion competition. Simulations reveal a three-stage process: initial uniformity, shear-driven heterogeneity (characterized by depletion in strain sheets and accumulation in vortex cores), and asymptotic re-homogenization driven by diffusion. The asymptotic solution demonstrates self-similar coagulation and exponential dependence on initial shear rate. This work provides a paradigm for predicting nanoparticle evolution in complex vortical flows and establishes a foundation for extending high-precision simulation tools to three-dimensional atmospheric nanoparticle evolution models.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106704"},"PeriodicalIF":2.9,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268101","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}
Pub Date : 2025-10-02DOI: 10.1016/j.jaerosci.2025.106703
Guilherme J.M. Garcia , Shamudra Dey
The nasal valve is a major barrier to nasal spray drug delivery to posterior structures such as the turbinates, paranasal sinuses, and olfactory region. Geometric considerations predict that the nasal spray dose that reaches the posterior nose is greater in subjects with larger nasal valve cross-sectional areas. Our analysis of the experimental data from Esmaeili et al. (2024) [Journal of Aerosol Science 179, 106387] reveals a paradoxical negative correlation between posterior dose and nasal valve area in pediatric nasal cavities. We hypothesize that the discrepancy between the theoretical prediction of the geometric model and experimental observation is due to the assumption in the geometric model that droplets are trapped and remain at the location where they hit the wall. A calculation of the Weber number suggests that nasal spray droplets >120 μm splash upon collision with the nasal walls, leading to the formation of smaller droplets that can be carried by airflow beyond the nasal valve. A study by Inthavong et al. (2015) suggests that 45 % of the spray mass is composed of droplets ≥120 μm at a distance of 0.6–1.2 cm from the nozzle tip, potentially leading to substantial splashing on the walls of the nasal vestibule. Traditionally, computational fluid dynamics models of nasal spray drug delivery have assumed a trap (stick) boundary condition and have not considered particle-wall interactions or post-deposition liquid motion. This study reviews the evidence that particle-wall interactions and post-deposition liquid motion may play a significant role in determining the regional doses of nasal sprays.
鼻阀是鼻腔喷雾剂向鼻甲、鼻窦和嗅觉区等后部结构输送的主要屏障。几何因素预测，鼻阀截面积较大的受试者到达后鼻的鼻喷雾剂量更大。我们对Esmaeili等人（2024）[Journal of Aerosol Science 179, 106387]的实验数据进行了分析，发现小儿鼻腔后剂量与鼻阀面积之间存在矛盾的负相关关系。我们假设几何模型的理论预测与实验观测之间的差异是由于几何模型中假设液滴被捕获并停留在它们撞击壁面的位置。韦伯数的计算表明，120 μm的鼻喷雾剂液滴在与鼻壁碰撞时飞溅，导致形成更小的液滴，这些液滴可以被气流带出鼻阀。Inthavong等人（2015）的一项研究表明，45%的喷雾质量由距离喷嘴尖端0.6-1.2 cm处≥120 μm的液滴组成，这可能导致在鼻前庭壁上大量飞溅。传统上，鼻腔喷雾剂给药的计算流体动力学模型假设了陷阱（粘）边界条件，没有考虑颗粒-壁相互作用或沉积后的液体运动。本研究综述了颗粒-壁相互作用和沉积后液体运动可能在确定鼻腔喷雾剂的区域剂量中起重要作用的证据。
{"title":"Nasal spray drug delivery beyond the nasal valve: Evidence for the importance of particle-wall interactions and post-deposition liquid motion","authors":"Guilherme J.M. Garcia , Shamudra Dey","doi":"10.1016/j.jaerosci.2025.106703","DOIUrl":"10.1016/j.jaerosci.2025.106703","url":null,"abstract":"<div><div>The nasal valve is a major barrier to nasal spray drug delivery to posterior structures such as the turbinates, paranasal sinuses, and olfactory region. Geometric considerations predict that the nasal spray dose that reaches the posterior nose is greater in subjects with larger nasal valve cross-sectional areas. Our analysis of the experimental data from Esmaeili et al. (2024) [Journal of Aerosol Science 179, 106387] reveals a paradoxical negative correlation between posterior dose and nasal valve area in pediatric nasal cavities. We hypothesize that the discrepancy between the theoretical prediction of the geometric model and experimental observation is due to the assumption in the geometric model that droplets are trapped and remain at the location where they hit the wall. A calculation of the Weber number suggests that nasal spray droplets >120 μm splash upon collision with the nasal walls, leading to the formation of smaller droplets that can be carried by airflow beyond the nasal valve. A study by Inthavong et al. (2015) suggests that 45 % of the spray mass is composed of droplets ≥120 μm at a distance of 0.6–1.2 cm from the nozzle tip, potentially leading to substantial splashing on the walls of the nasal vestibule. Traditionally, computational fluid dynamics models of nasal spray drug delivery have assumed a trap (stick) boundary condition and have not considered particle-wall interactions or post-deposition liquid motion. This study reviews the evidence that particle-wall interactions and post-deposition liquid motion may play a significant role in determining the regional doses of nasal sprays.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106703"},"PeriodicalIF":2.9,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268103","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}
Pub Date : 2025-09-26DOI: 10.1016/j.jaerosci.2025.106682
Brenda Vara Almirall , Narinder Singh , Hua Qian Ang , Kiao Inthavong
Accurate representation of oral airway geometry during inhalation is critical for optimizing drug delivery, yet the shape of the oral cavity and oropharynx varies significantly with breathing posture. This pilot study compares airflow dynamics and particle deposition between two CT-derived airway models from a single healthy subject: one with an artificially opened mouth during nasal breathing, and another with a real oral inhalation during active oral inhalation using a 2 cm mouthpiece. Computational fluid dynamics simulations were conducted at inhalation rates of 15, 30, and 60 L/min using spherical particles. The real-oral-inhalation model showed an enlarged oral cavity, smoother and more uniform airflow, peak pharyngeal velocities of 5–6 m/s, and an anteriorly directed laryngeal jet. This airway geometry eliminated oral cavity deposition and consistently shifted particle deposition deeper into the airway, resulting in 17–19.6% deposition in the larynx across all flow rates. In contrast, the artificially opened model produced higher peak velocities ( 7.5 m/s), jet-like flow impinging on the posterior pharyngeal wall, and persistent oral cavity deposition that increased with flow rate. Tracheal deposition remained minimal in both models. Differences in tongue and soft palate positioning, likely contributed to the observed aerodynamic and deposition patterns. These results highlight the role of imaging protocols that capture true inhalation posture and soft tissue configuration. Future studies that incorporate the realistic airway geometry during physiologically realistic breathing conditions may provide new inhalation drug delivery strategies and improve clinical relevance of CFD-based inhalation models.
{"title":"Impact of oral cavity geometry on micro-sized aerosol deposition in the upper airway during oral inhalation","authors":"Brenda Vara Almirall , Narinder Singh , Hua Qian Ang , Kiao Inthavong","doi":"10.1016/j.jaerosci.2025.106682","DOIUrl":"10.1016/j.jaerosci.2025.106682","url":null,"abstract":"<div><div>Accurate representation of oral airway geometry during inhalation is critical for optimizing drug delivery, yet the shape of the oral cavity and oropharynx varies significantly with breathing posture. This pilot study compares airflow dynamics and particle deposition between two CT-derived airway models from a single healthy subject: one with an artificially opened mouth during nasal breathing, and another with a real oral inhalation during active oral inhalation using a 2 cm mouthpiece. Computational fluid dynamics simulations were conducted at inhalation rates of 15, 30, and 60 L/min using spherical particles. The real-oral-inhalation model showed an enlarged oral cavity, smoother and more uniform airflow, peak pharyngeal velocities of 5–6 m/s, and an anteriorly directed laryngeal jet. This airway geometry eliminated oral cavity deposition and consistently shifted particle deposition deeper into the airway, resulting in 17–19.6% deposition in the larynx across all flow rates. In contrast, the artificially opened model produced higher peak velocities (<span><math><mo>≈</mo></math></span> 7.5 m/s), jet-like flow impinging on the posterior pharyngeal wall, and persistent oral cavity deposition that increased with flow rate. Tracheal deposition remained minimal in both models. Differences in tongue and soft palate positioning, likely contributed to the observed aerodynamic and deposition patterns. These results highlight the role of imaging protocols that capture true inhalation posture and soft tissue configuration. Future studies that incorporate the realistic airway geometry during physiologically realistic breathing conditions may provide new inhalation drug delivery strategies and improve clinical relevance of CFD-based inhalation models.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106682"},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221942","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}
Pub Date : 2025-09-26DOI: 10.1016/j.jaerosci.2025.106702
Mohamed Talaat , Xiuhua April Si , Jinxiang Xi
The effectiveness of metered-dose inhalers (MDIs) in drug delivery is significantly influenced by aerosol dynamics, particularly evaporation and release timing. This study examined the dynamic interactions between these two factors and their impact on deposition patterns in an anatomically realistic airway model. The airflow and thermo-humidity conditions were simulated under spray actuation conditions (i.e., 0.0, 0.7, 1.5, and 2.5 s after inhalation onset). A Lagrangian-based multiphase model, enhanced with adaptive droplet time steps, was used to track droplet evaporation, trajectory, and deposition. Experimentally measured MDI spray properties, including solution composition, polydisperse size distribution, plume angle, and release velocity, were implemented as initial/boundary conditions. Dosimetry was quantified based on both the count and mass of deposited droplets. Results revealed large differences in droplet evaporation between Case 0.0 s and the other three cases. For all release times, evaporation decreased droplet deposition in the mouth and increased deposition in the lower lung, particularly in the two upper lobes. Droplets starting at 5 μm in diameter reduced to 0.93–2.8 μm within 50–200 ms in the respiratory tract, whereas 10 μm droplets shrunk only to 7.5 μm. The spray deposition pattern varies notably depending on whether actuation occurs at the start of inhalation or is delayed by 0.7–2.5 s. This variation stems from slower airflow and extended evaporation time at the beginning of inhalation vs. relatively consistent and quicker evaporation rates in delayed actuation. Correction factors were introduced for delayed actuation cases to align deposition data obtained with and without accounting for droplet evaporation. Because of the initial polydisperse size distribution and subsequent evaporation of spray droplets, mass-based and count-based deposition fraction values in the lower lung differed by one order of magnitude. Further experimental studies are needed to validate predictions regarding droplet behavior and fate in the respiratory tract.
{"title":"Computational insights into dynamic impacts of droplet evaporation and spray release timing on MDI dosimetry in the respiratory tract","authors":"Mohamed Talaat , Xiuhua April Si , Jinxiang Xi","doi":"10.1016/j.jaerosci.2025.106702","DOIUrl":"10.1016/j.jaerosci.2025.106702","url":null,"abstract":"<div><div>The effectiveness of metered-dose inhalers (MDIs) in drug delivery is significantly influenced by aerosol dynamics, particularly evaporation and release timing. This study examined the dynamic interactions between these two factors and their impact on deposition patterns in an anatomically realistic airway model. The airflow and thermo-humidity conditions were simulated under spray actuation conditions (i.e., 0.0, 0.7, 1.5, and 2.5 s after inhalation onset). A Lagrangian-based multiphase model, enhanced with adaptive droplet time steps, was used to track droplet evaporation, trajectory, and deposition. Experimentally measured MDI spray properties, including solution composition, polydisperse size distribution, plume angle, and release velocity, were implemented as initial/boundary conditions. Dosimetry was quantified based on both the count and mass of deposited droplets. Results revealed large differences in droplet evaporation between Case 0.0 s and the other three cases. For all release times, evaporation decreased droplet deposition in the mouth and increased deposition in the lower lung, particularly in the two upper lobes. Droplets starting at 5 μm in diameter reduced to 0.93–2.8 μm within 50–200 ms in the respiratory tract, whereas 10 μm droplets shrunk only to 7.5 μm. The spray deposition pattern varies notably depending on whether actuation occurs at the start of inhalation or is delayed by 0.7–2.5 s. This variation stems from slower airflow and extended evaporation time at the beginning of inhalation vs. relatively consistent and quicker evaporation rates in delayed actuation. Correction factors were introduced for delayed actuation cases to align deposition data obtained with and without accounting for droplet evaporation. Because of the initial polydisperse size distribution and subsequent evaporation of spray droplets, mass-based and count-based deposition fraction values in the lower lung differed by one order of magnitude. Further experimental studies are needed to validate predictions regarding droplet behavior and fate in the respiratory tract.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106702"},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221943","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}
Pub Date : 2025-09-20DOI: 10.1016/j.jaerosci.2025.106699
Taewon T. Han , Atila Lima , Dong Ming He , Gary Brewer , Gediminas Mainelis
This research aimed to advance the development of a novel personal nasal sampler (PNS). PNS attaches to a user's nostrils and utilizes the user's breathing to capture airborne infectious agents on an advanced filter inside the PNS, thereby directly measuring actual personal exposure to those agents. Here, we designed, developed, and tested a hybrid filter (HF) to be used in PNS. The HF was designed by overlaying electrospun polyvinylidene fluoride (PVDF) nanofibers on a selected substrate for different durations. A suitable substrate was selected from meltblown and spunbond fabric filters of different densities, a MERV-5 carbon filter, and a pulmonary function test filter (PTF) based on their collection efficiencies and pressure drop. The candidate hybrid filters (HF) were then challenged with Arizona Road Dust particles aerosolized from a 2 % w/w slurry. The HF was 12.5 mm in diameter, corresponding to an average nostril diameter, and was operated at 5 and 10 L/min flow rates to simulate sedentary conditions and moderate exertion, respectively. The final HF showed collection efficiency of 60–70 % at 0.2–0.3 μm (most penetrating particle size) and >90 % for particles <0.05 μm and >0.7 μm. Its pressure drop was about 200 Pa. When challenged with enveloped bacteriophage Phi6, this HF showed recovery efficiencies of 99 % and 80 % at 5 and 10 L/min flow rates, respectively. In the next steps, the HF will be incorporated into a biocompatible holder and extensively tested in laboratory and field conditions for its ability to measure exposure to bioaerosols.
{"title":"Development of an advanced personal nasal sampler (PNS) to access exposure to bioaerosols","authors":"Taewon T. Han , Atila Lima , Dong Ming He , Gary Brewer , Gediminas Mainelis","doi":"10.1016/j.jaerosci.2025.106699","DOIUrl":"10.1016/j.jaerosci.2025.106699","url":null,"abstract":"<div><div>This research aimed to advance the development of a novel personal nasal sampler (PNS). PNS attaches to a user's nostrils and utilizes the user's breathing to capture airborne infectious agents on an advanced filter inside the PNS, thereby directly measuring actual personal exposure to those agents. Here, we designed, developed, and tested a hybrid filter (HF) to be used in PNS. The HF was designed by overlaying electrospun polyvinylidene fluoride (PVDF) nanofibers on a selected substrate for different durations. A suitable substrate was selected from meltblown and spunbond fabric filters of different densities, a MERV-5 carbon filter, and a pulmonary function test filter (PTF) based on their collection efficiencies and pressure drop. The candidate hybrid filters (HF) were then challenged with Arizona Road Dust particles aerosolized from a 2 % w/w slurry. The HF was 12.5 mm in diameter, corresponding to an average nostril diameter, and was operated at 5 and 10 L/min flow rates to simulate sedentary conditions and moderate exertion, respectively. The final HF showed collection efficiency of 60–70 % at 0.2–0.3 μm (most penetrating particle size) and >90 % for particles <0.05 μm and >0.7 μm. Its pressure drop was about 200 Pa. When challenged with enveloped bacteriophage Phi6, this HF showed recovery efficiencies of 99 % and 80 % at 5 and 10 L/min flow rates, respectively. In the next steps, the HF will be incorporated into a biocompatible holder and extensively tested in laboratory and field conditions for its ability to measure exposure to bioaerosols.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106699"},"PeriodicalIF":2.9,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119716","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}
Pub Date : 2025-09-20DOI: 10.1016/j.jaerosci.2025.106701
Aonan He , Zhenhai Qin , Jie Luo , Yupin Sun , Yuxin Miao , Qixing Zhang
Necking substantially improves the representation of black carbon (BC) morphology. However, recent studies placed more focused on bare BC particles and overlooked that the realistic BC emitted from biomass burning are often thickly coated. This paper investigates the effect of necking on the coated BC optical properties and applies the modified cylindrical connector model for necking and the parameter-tunable algorithm for coating. Results indicate that necking enhances the scattering matrix elements, and its effect increases with coating thickness and fractal dimension. Necking contributes a 10 %–30 % increase in absorption and scattering cross-sections, which is crucial for assessment of the radiative effects of the BC fraction in wildfire smoke. Additionally, necking provides a better explanation for high linear depolarization ratios observed in wildfire smoke. For low fractal dimension cases, necking reduces the lidar ratio. Conversely, necking has a minimal influence on single-scattering albedo.
{"title":"The effects of necking on the optical properties of coated black carbon aggregates","authors":"Aonan He , Zhenhai Qin , Jie Luo , Yupin Sun , Yuxin Miao , Qixing Zhang","doi":"10.1016/j.jaerosci.2025.106701","DOIUrl":"10.1016/j.jaerosci.2025.106701","url":null,"abstract":"<div><div>Necking substantially improves the representation of black carbon (BC) morphology. However, recent studies placed more focused on bare BC particles and overlooked that the realistic BC emitted from biomass burning are often thickly coated. This paper investigates the effect of necking on the coated BC optical properties and applies the modified cylindrical connector model for necking and the parameter-tunable algorithm for coating. Results indicate that necking enhances the scattering matrix elements, and its effect increases with coating thickness and fractal dimension. Necking contributes a 10 %–30 % increase in absorption and scattering cross-sections, which is crucial for assessment of the radiative effects of the BC fraction in wildfire smoke. Additionally, necking provides a better explanation for high linear depolarization ratios observed in wildfire smoke. For low fractal dimension cases, necking reduces the lidar ratio. Conversely, necking has a minimal influence on single-scattering albedo.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106701"},"PeriodicalIF":2.9,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156569","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}
Pub Date : 2025-09-19DOI: 10.1016/j.jaerosci.2025.106700
Anton Patarashvili, Alexey Efimov, Dmitry Maslennikov, Matthew Ivanov, Dmitry Labutov, Ekaterina Kameneva, Olesya Vershinina, Victor Ivanov
This study presents an optimized spark-discharge generator circuit that enhances unipolar ion production (up to 109 ions/cm3) without any ionizers, enabling efficient generation of charged ultrafine nanoparticles (<5 nm). By sustaining high voltage on both electrodes during discharge, the system achieves stable and controllable unipolar ionization. Systematic evaluation of key parameters (interelectrode gap, electrode material, discharge frequency, capacitance, gas flow/type, and voltage polarity) reveals optimal conditions for ion generation. Deposition experiments on silicon substrates and TEM grids confirm a 4-fold increase in sub-5 nm charged nanoparticle production compared to conventional designs, as validated by TEM, SEM and optical profilometry.
{"title":"Charged ultrafine nanoparticle synthesis by spark-discharge","authors":"Anton Patarashvili, Alexey Efimov, Dmitry Maslennikov, Matthew Ivanov, Dmitry Labutov, Ekaterina Kameneva, Olesya Vershinina, Victor Ivanov","doi":"10.1016/j.jaerosci.2025.106700","DOIUrl":"10.1016/j.jaerosci.2025.106700","url":null,"abstract":"<div><div>This study presents an optimized spark-discharge generator circuit that enhances unipolar ion production (up to 10<sup>9</sup> ions/cm<sup>3</sup>) without any ionizers, enabling efficient generation of charged ultrafine nanoparticles (<5 nm). By sustaining high voltage on both electrodes during discharge, the system achieves stable and controllable unipolar ionization. Systematic evaluation of key parameters (interelectrode gap, electrode material, discharge frequency, capacitance, gas flow/type, and voltage polarity) reveals optimal conditions for ion generation. Deposition experiments on silicon substrates and TEM grids confirm a 4-fold increase in sub-5 nm charged nanoparticle production compared to conventional designs, as validated by TEM, SEM and optical profilometry.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106700"},"PeriodicalIF":2.9,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156568","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}
Pub Date : 2025-09-18DOI: 10.1016/j.jaerosci.2025.106697
Kawkab Ahasan, Md Sadiqul Islam, Pranav Shrotriya, Todd A. Kingston
Growing concerns about public health and national security necessitate the development of compact, integrated systems capable of continuous, real-time collection and detection of biothreats (e.g., viruses and bacteria). In this work, we report an inertial microfluidic-based aerosol capture device for the real-time collection and analysis of airborne particles (e.g., biothreats), motivated by the need for rapid detection capabilities. A two-stage spiral microchannel is designed, fabricated, and evaluated for capturing aerosolized particles with diameters ranging from 0.20 to 1.60 μm, and its performance is compared to a traditional U-shaped microchannel. The spiral microchannel design is developed with the aid of multiphase computational fluid dynamics (CFD) simulations and tested experimentally to investigate the flow dynamics and particle capture efficiencies. Overall, the experimentally measured particle capture efficiencies agreed well with the simulation results and the two-stage spiral microchannel resulted in significant improvement over the traditional U-shaped microchannel. Both the simulations and experiments on the spiral microchannel design demonstrated approximately a two-fold increase in diversion efficiency and a five-fold increase in entrapment efficiency, on average, while having less than a two-fold increase in pressure drop. The performance improvement in the two-stage spiral microchannel design suggests a promising avenue for the development of next-generation devices capable of providing real-time collection and enrichment of aerosolized biothreats.
{"title":"Stratified two-phase microfluidic device for continuous sampling of sub-micron aerosolized particles","authors":"Kawkab Ahasan, Md Sadiqul Islam, Pranav Shrotriya, Todd A. Kingston","doi":"10.1016/j.jaerosci.2025.106697","DOIUrl":"10.1016/j.jaerosci.2025.106697","url":null,"abstract":"<div><div>Growing concerns about public health and national security necessitate the development of compact, integrated systems capable of continuous, real-time collection and detection of biothreats (e.g., viruses and bacteria). In this work, we report an inertial microfluidic-based aerosol capture device for the real-time collection and analysis of airborne particles (e.g., biothreats), motivated by the need for rapid detection capabilities. A two-stage spiral microchannel is designed, fabricated, and evaluated for capturing aerosolized particles with diameters ranging from 0.20 to 1.60 μm, and its performance is compared to a traditional U-shaped microchannel. The spiral microchannel design is developed with the aid of multiphase computational fluid dynamics (CFD) simulations and tested experimentally to investigate the flow dynamics and particle capture efficiencies. Overall, the experimentally measured particle capture efficiencies agreed well with the simulation results and the two-stage spiral microchannel resulted in significant improvement over the traditional U-shaped microchannel. Both the simulations and experiments on the spiral microchannel design demonstrated approximately a two-fold increase in diversion efficiency and a five-fold increase in entrapment efficiency, on average, while having less than a two-fold increase in pressure drop. The performance improvement in the two-stage spiral microchannel design suggests a promising avenue for the development of next-generation devices capable of providing real-time collection and enrichment of aerosolized biothreats.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106697"},"PeriodicalIF":2.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221940","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}
Pub Date : 2025-09-17DOI: 10.1016/j.jaerosci.2025.106681
Maximilian Karsch, Andreas Kronenburg
Agglomeration dynamics of nano-sized particles in aerosol flame reactors are dominated by the effects of Brownian diffusion and turbulent shear. In this study, we perform population balance calculations to predict the evolution of an initially monodisperse nanoparticle population in a turbulent carrier gas. To evaluate the required coagulation rate coefficients for the resulting agglomerates, we extend a recently developed model for spherical particles by a suitable expression for the effective collision cross-section. Population balance calculations are validated by detailed particle simulations where trajectories of all primary particles and agglomerates are directly resolved and the structure of the agglomerates is preserved. The primary particle sizes considered here range from 50 to , corresponding to Knudsen numbers between 2.3 and 4.6.
Our results show that collision rates measured from detailed particle simulations are in good agreement with predictions by the extended collision kernel model. In contrast, comparisons with a standard model from the literature reveal systematic differences which can be as large as an order of magnitude and more depending on the conditions. In addition, the effect of morphology on the measured collision rates is found to be rather small due to an opposing effect of the effective collision diameter and the particle inertia.
An a posteriori comparison between direct numerical simulations and population balance calculations suggests that the extended collision kernel model is able to correctly reproduce the evolution of the agglomerate population. The standard model, on the contrary, yields slower agglomeration rates compared to the direct simulation as it neglects particle inertia effects and thus underestimates turbulence-driven collision rates between large nanoparticle agglomerates.
{"title":"Modelling the collision kernel of fractal nanoparticle agglomerates in homogeneous isotropic turbulence","authors":"Maximilian Karsch, Andreas Kronenburg","doi":"10.1016/j.jaerosci.2025.106681","DOIUrl":"10.1016/j.jaerosci.2025.106681","url":null,"abstract":"<div><div>Agglomeration dynamics of nano-sized particles in aerosol flame reactors are dominated by the effects of Brownian diffusion and turbulent shear. In this study, we perform population balance calculations to predict the evolution of an initially monodisperse nanoparticle population in a turbulent carrier gas. To evaluate the required coagulation rate coefficients for the resulting agglomerates, we extend a recently developed model for spherical particles by a suitable expression for the effective collision cross-section. Population balance calculations are validated by detailed particle simulations where trajectories of all primary particles and agglomerates are directly resolved and the structure of the agglomerates is preserved. The primary particle sizes considered here range from 50 to <span><math><mrow><mn>100</mn><mspace></mspace><mi>nm</mi></mrow></math></span>, corresponding to Knudsen numbers between 2.3 and 4.6.</div><div>Our results show that collision rates measured from detailed particle simulations are in good agreement with predictions by the extended collision kernel model. In contrast, comparisons with a standard model from the literature reveal systematic differences which can be as large as an order of magnitude and more depending on the conditions. In addition, the effect of morphology on the measured collision rates is found to be rather small due to an opposing effect of the effective collision diameter and the particle inertia.</div><div>An a posteriori comparison between direct numerical simulations and population balance calculations suggests that the extended collision kernel model is able to correctly reproduce the evolution of the agglomerate population. The standard model, on the contrary, yields slower agglomeration rates compared to the direct simulation as it neglects particle inertia effects and thus underestimates turbulence-driven collision rates between large nanoparticle agglomerates.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106681"},"PeriodicalIF":2.9,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145097631","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}
Ionic liquids (ILs) are ambient-temperature molten salts that exhibit excellent CO2 absorption properties. Because ILs are composed of anions and cations, they have high conductivity. Electrospray is one of the key atomization techniques used to enhance the CO2 absorption performance of ILs by increasing the specific surface area of IL nanodroplets. To improve CO2 absorption performance further, in this study, a novel opposing-electrospray configuration was developed, in which two nozzles are placed facing each other so that the IL sprays from both nozzles interfere with each other. The effects of opposing electrospray were clarified through spray visualization, droplet diameter measurements, and CO2 absorption performance in a flow reactor. Spray visualization shows that the opposing-electrospray configuration generates a radially wider spray owing to electric field variation and Coulomb repulsion between positively charged droplets. In addition, the enhanced atomization of the IL for the opposing-electrospray configuration was confirmed through droplet size distribution measurements. Consequently, the opposing electrospray of the IL clearly improves the CO2 absorption amount and loading rate (the ratio of molar amount of absorbed CO2 to that of supplied IL) owing to the enhanced atomization with a more widely spreading spray. However, when the distance between the facing nozzles is increased, the spray interference is suppressed, leading to no significant change in the droplet diameter distribution and less improvement of CO2 absorption performance. These findings suggest that the opposing-electrospray configuration induces spray interference, which in turn enhances the CO2 absorption by promoting radially wider spray and atomization.
{"title":"Enhanced CO2 selective absorption by opposing ionic liquid electrospray","authors":"Yutaka Kaneko , Yusuke Onodera , Takashi Makino , Mitsuhiro Kanakubo , Hidemasa Takana","doi":"10.1016/j.jaerosci.2025.106695","DOIUrl":"10.1016/j.jaerosci.2025.106695","url":null,"abstract":"<div><div>Ionic liquids (ILs) are ambient-temperature molten salts that exhibit excellent CO<sub>2</sub> absorption properties. Because ILs are composed of anions and cations, they have high conductivity. Electrospray is one of the key atomization techniques used to enhance the CO<sub>2</sub> absorption performance of ILs by increasing the specific surface area of IL nanodroplets. To improve CO<sub>2</sub> absorption performance further, in this study, a novel opposing-electrospray configuration was developed, in which two nozzles are placed facing each other so that the IL sprays from both nozzles interfere with each other. The effects of opposing electrospray were clarified through spray visualization, droplet diameter measurements, and CO<sub>2</sub> absorption performance in a flow reactor. Spray visualization shows that the opposing-electrospray configuration generates a radially wider spray owing to electric field variation and Coulomb repulsion between positively charged droplets. In addition, the enhanced atomization of the IL for the opposing-electrospray configuration was confirmed through droplet size distribution measurements. Consequently, the opposing electrospray of the IL clearly improves the CO<sub>2</sub> absorption amount and loading rate (the ratio of molar amount of absorbed CO<sub>2</sub> to that of supplied IL) owing to the enhanced atomization with a more widely spreading spray. However, when the distance between the facing nozzles is increased, the spray interference is suppressed, leading to no significant change in the droplet diameter distribution and less improvement of CO<sub>2</sub> absorption performance. These findings suggest that the opposing-electrospray configuration induces spray interference, which in turn enhances the CO<sub>2</sub> absorption by promoting radially wider spray and atomization.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"191 ","pages":"Article 106695"},"PeriodicalIF":2.9,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156570","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}
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