Search Results (253)

Electret filter media are electrostatically charged during the manufacturing process to activate effective electrical separation mechanisms. In order to investigate the influence of humidity on these mechanisms, the electric field, and filtration efficiency, a Direct Numerical Simulation (DNS) study of the aerosol deposition within wetted fibrous nonwoven filter media used in masks was carried out. Initial experimental investigations determined key properties of the filter material, including porosity, fiber diameter, and surface charge density. Using Micro-Computed Tomography (µCT), preferred locations for droplet deposition within the filter were identified. Additional experiments quantified the amount of water absorbed by the filter medium and assessed its impact on the existing electric field. Numerical simulations examined various models with differing porosity and fiber diameter, incorporating different levels of water content to analyze the changes in the electric field, flow velocity, and resulting filtration efficiency. The results provide valuable insights into the significant effects of fiber change on filtration performance, demonstrating the electret filter’s ability to partially compensate for the negative impacts of water. Full article

The growing demands for sanitary regulations in medical facilities, particularly operating rooms, highlight the importance of ensuring high air quality and minimizing airborne hospital-acquired infections. Improperly designed ventilation systems may lead to contamination of up to 90–95% of patients, especially in light of evolving threats, such as COVID-19. This study focuses on enhancing the energy efficiency and performance of air conditioning and ventilation systems for cleanrooms, where air recirculation is not permissible. A novel energy-efficient direct-flow air treatment scheme is proposed, integrating a heat pump system with adjustable thermal output. A computational fluid dynamics CFD model of a clean operating room was developed to assess the impact of inlet air velocity on aerosol particle removal and airflow stabilization time. The model also considers the effect of personnel movement. The results supported optimized air distribution, reducing microbial contamination risks, with less than 10 CFU/m³, and improved thermal performance. The proposed system was evaluated for energy and cost efficiency compared to conventional setups. Findings can inform the design and operation of cleanroom ventilation in surgical environments and other high-tech applications. This research contributes to improving indoor air quality and reducing infection risks while enhancing sustainability in healthcare infrastructure. Full article

Healthcare providers performing aerosol-generating procedures (AGPs) face significant infection risks, emphasizing the critical need for effective aerosol containment systems. In this study, we developed and validated a negative pressure chamber enhanced with an innovative aerodynamic cap structure designed to optimize aerosol containment. Initially, computational fluid dynamics (CFD) simulations were performed to evaluate multiple structural improvement ideas, including air curtains, bidirectional suction, and aerodynamic cap structures. Among these, the aerodynamic cap was selected due to its superior predicted containment performance, practical feasibility, and cost-effectiveness. The CFD analyses employed realistic transient boundary conditions, precise turbulence modeling using the shear stress transport (SST) k–ω model, and detailed droplet evaporation dynamics under realistic humidity conditions. A full-scale prototype incorporating the selected aerodynamic cap was fabricated and evaluated using physical polyalphaolefin (PAO) particle leakage tests and biological aerosol validation with aerosolized Bacillus subtilis. For the physical leakage tests, the chamber opening was divided into nine sections, and the aerosol dispersion was tested in three distinct directions: ceiling-directed, toward the suction hole, and opposite the suction hole. These tests demonstrated significantly stabilized airflow and substantial reductions in aerosol leakage, consistently maintaining containment levels below the critical threshold of 0.3%, especially under transient coughing conditions. The biological aerosol experiments, conducted in a simulated emergency department environment, involved aerosolizing bacteria continuously for one hour. The results confirmed the effectiveness of the aerodynamic cap structure in achieving at least a one millionth (10⁻⁶) reduction in the aerosolized bacterial leakage compared to the control conditions. These findings highlight the importance and effectiveness of advanced CFD modeling methodologies in accurately predicting aerosol dispersion and improving containment strategies. Although further studies assessing the structural durability, long-term operational ease, and effectiveness against pathogenic microorganisms are required, the aerodynamic cap structure presents a promising, clinically practical infection control solution for widespread implementation during aerosol-generating medical procedures. Full article

The term ‘vaping’ refers to the use of electronic cigarettes or other devices to inhale a variety of heated and aerosolized substances. Vaping has been promoted as a less harmful and potentially oncogenic alternative to nicotine cigarettes, particularly to help heavy smokers quit. While vaping products do not produce the same carcinogenic substances—such as polycyclic aromatic hydrocarbons—generated by the combustion of tobacco, and while their fluids lack tobacco-related carcinogens like nitrosamines, it is now well established that they still generate harmful and potentially oncogenic byproducts. Several mechanisms have been proposed to explain the potential oncogenic effects of vaping fluids, including direct chemical action, epithelial–mesenchymal transition induction, redox stress, mitochondrial toxicity, and DNA damage. In addition to cancer risk, there have been reports of adverse effects on cardiovascular health, reproductive function, and non-oncologic lung injuries. These include exogenous lipoid pneumonia, diffuse alveolar hemorrhage with proven alveolar injury, and vaping-associated bronchiolitis obliterans. The aim of this review is to examine vaping devices, their potential role in lung carcinogenesis, vaping-associated lung injury, and other clinical implications, including impacts on cardiovascular, cerebrovascular, and respiratory diseases, and also pregnancy and fetus health. Full article

A traditional SAW (surface acoustic wave) atomizer directly supplies liquid to the surface of the atomized chip through a paper strip located in the path of the acoustic beam, resulting in irregular distribution of the liquid film, which generates an aerosol with an uneven particle size distribution and poor directional controllability, and a high heating phenomenon that can easily break the chip in the atomization process. This paper presents a novel atomization method: a paper strip located at the edge of the atomizer (PSLEA), which forms a micron-sized narrow liquid film at the junction of the atomization chip edge and the paper strip under the effect of acoustic wetting. By using this method, physical separation of the atomized aerosol and jetting droplets can be achieved at the initial stage of atomizer startup, and an ideal aerosol plume with no jetting of large droplets, a uniform particle size distribution, a vertical and stable atomization direction, and good convergence of the aerosol beam can be quickly formed. Furthermore, the effects of the input power, and different paper strips and liquid supply methods on the atomization performance, as well as the heating generation capacity of the liquid in the atomization zone during the atomization process were explored through a large number of experiments, which highlighted the advantages of PSLEA atomization. The experiments demonstrated that the maximum atomization rate under the PSLEA atomization mode reached 2.6 mL/min initially, and the maximum thermal stress was 45% lower compared with that in the traditional mode. Additionally, a portable handheld atomizer with stable atomization performance and a median aerosol particle size of 3.95 μm was designed based on the proposed PSLEA atomization method, showing the great potential of SAW atomizers in treating respiratory diseases. Full article

In this study, we evaluate aerosol, cloud, and radiation interactions in GFS.V17.p8 (Global Forecast System System Version 17 prototype 8). Two experiments were conducted for the summer of 2020. In the control experiment (EXP CTL), aerosols interact with radiation only, incorporating direct and semi-direct aerosol effects. The sensitivity experiment (EXP ACI) couples aerosols with both radiation and Thompson microphysics, accounting for aerosol indirect effects and fully interactive aerosol–cloud dynamics. Introducing aerosol and cloud interactions results in net cooling at the top of the atmosphere (TOA). Further analysis shows that the EXP ACI produces more liquid water at lower levels and less ice water at higher levels compared to the EXP CTL. The aerosol optical depth (AOD) shows a good linear relationship with cloud droplet number concentration, similar to other climate models, though with larger standard deviations. Including aerosol and cloud interactions generally enhances simulations of the Indian Summer Monsoon, stratocumulus, and diurnal cycles. Additionally, the study evaluates the impacts of aerosols on deep convection and cloud life cycles. Full article

Biomass burning (BB) aerosols are the largest source of absorbing aerosols on Earth. Coupled with marine stratocumulus clouds (MSC), their radiative effects are enhanced and can cause cloud property changes (first indirect effect) or cloud burn-off and warm up the atmospheric column (semi-direct effect). Nevertheless, the derivation of their quantity and optical properties in the presence of MSC clouds is confounded by the uncertainties in the retrieval of the underlying cloud properties. Therefore, a robust methodology is needed for the coupled retrievals of absorbing aerosol above clouds. Here, we present a new retrieval approach implemented for a Spectro radiometric multi-angle polarimetric airborne platform, the research scanning polarimeter (RSP), during the ORACLES campaign over the Southeast Atlantic Ocean. Our approach transforms the 1D measurements over multiple angles and wavelengths into a 3D image-like input, which is then processed using various deep learning (DL) schemes to yield aerosol single scattering albedos (SSAs), aerosol optical depths (AODs), aerosol effective radii, and aerosol complex refractive indices, together with cloud optical depths (CODs), cloud effective radii and variances. We present a comparison between the different DL approaches, as well as their comparison to existing algorithms. We discover that the Vision Transformer (ViT) scheme, traditionally used by natural language models, is superior to the ResNet convolutional Neural-Network (CNN) approach. We show good validation statistics on synthetic and real airborne data and discuss paths forward for making this approach flexible and readily applicable over multiple platforms. Full article

Volatile organic compound (VOC) emissions have become a critical environmental concern due to their contributions to photochemical smog formation, secondary organic aerosol generation, and adverse human health impacts in the context of accelerated industrialization and urbanization. Catalytic oxidation over perovskite-type catalysts is an attractive technological approach for efficient VOC abatement. This review systematically evaluates the advancements in perovskite-based catalysts for VOC oxidation, focusing on their crystal structure–activity relationships, electronic properties, synthetic methodologies, and nanostructure engineering. Emphasis is placed on metal ion doping strategies and supported catalyst configurations, which have been demonstrated to optimize catalytic performance through synergistic effects. The applications of perovskite catalysts in diverse oxidation systems, including photocatalysis, thermal catalysis, electrocatalysis, and plasma-assisted catalysis, are comprehensively discussed with critical analysis of their respective advantages and limitations. It summarizes the existing challenges, such as catalyst deactivation caused by carbon deposition, sulfur/chlorine poisoning, and thermal sintering, as well as issues like low energy utilization efficiency and the generation of secondary pollutants. By consolidating current knowledge and highlighting future research directions, this review provides a solid foundation for the rational design of next-generation perovskite catalysts for sustainable VOC management. Full article

(1) Background: the aim of this study is to assess the effectiveness of two protection systems for aerosol cloud reduction while playing different wind instruments. (2) Methods: The protection systems used were a cotton molton construction combined with a bell filter attached at the bell of the instruments, as well as a household paper towel. For visualization of the emitted aerosol particles, e-cigarettes were used. With three full HD cameras, cloud dispersion was captured in the forward, sideways, and upwards directions. The effectiveness of aerosol spread reduction was statistically evaluated. (3) Results: Without protection, aerosol clouds dispersed, on average, up to 1.23 m in the forward direction, 0.46 m sideways, and 0.86 m upwards. The cotton molton mask reduced forward spread by 42%, while the paper towel achieved a 15% reduction, although both systems increased lateral and vertical dispersion. Specifically, the cotton molton mask yielded a 9% increase to the side and 7% in the upward direction, while the paper towel resulted in a 66% increase to the sides and a 10% increase in the upward direction. The cotton molton mask’s effectiveness was attributed to its additional coverage of the tone holes, which contribute to aerosol emission in woodwind instruments. A statistical analysis via the Friedman test confirmed significant reductions in forward dispersion with the cotton molton system. (4) Conclusions: Protective systems can partially reduce aerosol emissions. However, these alone are not sufficient, and further measures to reduce the spread of particles are necessary. Full article

Nickel, as a toxic trace element in fine particulate matter (PM_2.5), has detrimental effects on both air quality and human health. Based on measurements from 2020 to 2021 using a single-particle aerosol mass spectrometer (SPAMS), this study investigates the properties of nickel-containing particles (NCPs) in Guangzhou. The composition, sources, and temporal trends of NCPs were evaluated and the impact of the clean ship fuel policy introduced in 2020 was also examined. The key findings include: (1) Nickel particles account for 0.08% number fraction of PM_2.5, which is consistent with previously reported mass fraction in PM_2.5. (2) Three distinct types of NCPs were identified, including Ni-fresh, Ni-aged, and Ni-ash. Each type exhibits unique characteristics in size distribution, wind direction dependence, sources, and temporal variations. Ni-fresh particles originate from shipping emissions in the Huangpu Port area 2 km away and are the major contributors to fine nickel particles in the region. (3) Ni-aged and Ni-ash particles, which carry secondary components, tend to be larger (>500 nm) and are representative of regional or background nickel particles. (4) The implementation of the clean ship fuel policy has effectively reduced the number concentrations of NCPs and is beneficial to regional and local air quality. Full article

This study focused on addressing the issue of delayed root system development in mulberry trees during aerosol cultivation, which is attributed to the asynchronous growth of branches and buds. To tackle this challenge, we propose an intelligent foliar fertilizer spraying system based on deep learning. The system incorporates a parallel robotic arm spraying device and employs trinocular vision to capture image datasets of mulberry tree branches. After comparing YOLOv8n with other YOLO versions, we made several enhancements to the YOLOv8n model. These improvements included the introduction of the Asymptotic Feature Pyramid Network (AFPN), the optimization of feature extraction using the MSBlock module, the adoption of a dynamic ATSS label assignment strategy, and the replacement of the CIoU loss function with the Focal_XIoU loss function. Furthermore, an artificial neural network was utilized to calculate the coordinates of the robotic arm. The experimental results demonstrate that the enhanced YOLOv8n model achieved an average precision of 94.48%, representing a 6.05% improvement over the original model. Additionally, the prediction error for the robotic arm coordinates was maintained at ≤1.3%. This system effectively enables the precise location and directional fertilization of mulberry branches exhibiting lagging growth, thereby significantly promoting the synchronous development of mulberry seedlings. Full article

This research aims to estimate long-term aerosol radiative effects by combining radiation and Aerosol Optical Depth (AOD) observations in Barcelona, Spain. Aerosol Radiative Forcing and Aerosol Forcing Efficiency (ARF and AFE) were estimated by combining shortwave radiation measurements from a SolRad-Net CM-21 pyranometer (level 1.5) and AERONET AOD (level 2), using the direct method. The shortwave AFE was derived from the slope between net solar radiation and AOD at 440, 675, 879, and 1020 nm, and the ARF was computed by multiplying the AFE by AOD at six solar zenith angles (20°, 30°, 40°, 50°, 60°, and 70°). Clear-sky conditions were selected from all-skies days by a quadratic fitting. The aerosol was classified to investigate the forcing contributions from each aerosol type. The aerosol classification was based on Pace and Toledano’s thresholds from AOD vs. Ångström Exponent (AE). The GRASP inversions were performed by combined AOD, radiation, Degree of Linear Polarization (DoLP) by zenith angles from the polarized sun–sky–lunar photometer and the elastic signal from the UPC-ACTRIS lidar system. The long-term AFE and ARF are both negative, with an increasing tendency (in absolute value) of +24% (AFE) and +40% (ARF) in 14 years. The yearly AFE varied from −331 to −10 Wm⁻²τ⁻¹, and the ARF varied from −64 to −2 Wm⁻², associated with an AOD (440 nm) from 0.016 to 0.690. The three types of aerosols on clear-sky days are mixed aerosols (61%), desert dust (10%), and urban/industrial-biomass burning aerosols (29%). Combined with Gobbi’s method, this classification clustered the aerosols into four groups by AE analysis (two coarse- and two fine-mode aerosols). Then, the contribution of the aerosol types to the ARF showed that the desert dust forcing had the largest cooling effect in Barcelona (−61.5 to −37.4 Wm⁻²), followed by urban/industrial-biomass burning aerosols (−40.4 to −20.4 Wm⁻²) and mixed aerosols (−31.8 and −24.0 Wm⁻²). Regarding the comparison among Generalized Retrieval of Atmosphere and Surface Properties (GRASP) inversions, AERONET inversions, and direct method estimations, the AFE and ARF had some differences owing to their definitions in the algorithms. The DoLP, used as GRASP input, decreased the ARF overestimation for high AOD. Full article

During the South Asian Summer Monsoon (SASM), intense large-scale uplift and strong deep convective activity over South Asia lead to the formation of a high aerosol concentration zone in the Upper Troposphere and Lower Stratosphere (UTLS), known as the Asian Troposphere Aerosol Layer (ATAL), which appears from June to August. ATAL not only influences the exchange processes of material and energy between the troposphere and stratosphere, but also affects the global climate by altering radiation, cloud formation, and precipitation processes. Therefore, examining the spatiotemporal distribution and climate impacts of ATAL is essential for understanding climate change and evaluating the feasibility of geoengineering. This study systematically reviews research progress on the three-dimensional spatiotemporal distribution, trends, sources, and climatic effects of ATAL. Findings reveal a prominent aerosol layer at the top of the Asian troposphere, and the SASM region potentially serving as a critical conduit for constituents of the boundary layer to reach the stratosphere. However, simulated ATAL components differ significantly across models, particularly in terms of vertical distribution patterns. The precise three-dimensional structure and long-term evolution of ATAL remain unclear, presenting challenges for assessing its climate impact. To advance the understanding of the roles of ATAL in climate change, three future research directions are proposed. Full article

The COVID-19 pandemic has highlighted the significant infection risks posed by aerosol generating procedures (AGPs). We developed a hood that covers the patient’s respiratory area, incorporating a negative pressure system to contain aerosols. This study analyzed the movement and containment of aerosols within a developed negative pressure isolation chamber. Using particle image velocimetry (PIV) technology, in the optimized design, the characteristics of aerosols were analyzed under both negative and non-negative pressure conditions. The results demonstrated that in the absence of negative pressure, droplets dispersed widely, with diffusion angles ranging from 26.9° to 34.2°, significantly increasing the risk of external leakage. When negative pressure was applied, the diffusion angles narrowed to 20.0–35.1° and inward airflow effectively directed droplets away from the chamber boundary, preventing external dispersion. Additionally, sensor data measuring particle concentrations confirmed that droplets smaller than 10 µm were fully contained under negative pressure, strongly supporting the chamber’s effectiveness. The strong agreement between PIV flow patterns and sensor measurements underscores the reliability of the experimental methodology. These findings highlight the chamber’s ability to suppress external leakage while offering superior flexibility and portability compared to conventional isolation systems, making it ideal for emergency responses, mobile healthcare units, and large-scale infectious disease outbreaks. Full article

Zoonotic viruses have significant pandemic potential, as evidenced by the coronavirus pandemic, which underscores that zoonotic infections have historically caused numerous outbreaks and millions of deaths over centuries. Zoonotic viruses induce numerous types of illnesses in their natural hosts. These viruses are transmitted to humans via biological vectors, direct contact with infected animals or their bites, and aerosols. Zoonotic viruses continuously evolve and adapt to human hosts, resulting in devastating consequences. It is very important to understand pathogenesis pathways associated with zoonotic viral infections across various hosts and develop countermeasure strategies accordingly. In this review, we briefly discuss advancements in diagnostics and therapeutics for zoonotic viral infections. It provides insight into recent outbreaks, viral dynamics, licensed vaccines, as well as vaccine candidates progressing to clinical investigations. Despite advancements, challenges persist in combating zoonotic viruses due to immune evasion, unpredicted outbreaks, and the complexity of the immune responses. Most of these viruses lack effective treatments and vaccines, relying entirely on supportive care and preventive measures. Exposure to animal reservoirs, limited vaccine access, and insufficient coverage further pose challenges to preventive efforts. This review highlights the critical need for ongoing interdisciplinary research and collaboration to strengthen preparedness and response strategies against emerging infectious threats. Full article