Caustic singularities of the spatial distribution of particles in turbulent aerosols enhance collision rates and accelerate coagulation. Here we investigate how and where caustics form at weak particle inertia, by ana...
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A detailed analysis of the distributions of the electric potential obtained during the simulation of several thunderstorms in Moscow and Siberia was carried out. The aim of this work was to study the effect of aerosol...
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Fine particulate matter (PM2.5) significantly impacts global air quality and human health due to its smaller particle size and larger specific surface area. Nitrogen and carbon aerosols, as the main components of PM2....
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Objective: We designed an in vitro study to evaluate the efficiency of an 0.5 vol% hydrogen peroxide-based spray in reducing Coronavirus 229E spread during a conventional dental procedure. Methods: A class III cabinet...
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Objective: We designed an in vitro study to evaluate the efficiency of an 0.5 vol% hydrogen peroxide-based spray in reducing Coronavirus 229E spread during a conventional dental procedure. Methods: A class III cabinet-like chamber was custom-built, using phantoms for both patient and operator. A suspension of HCoV-229E in artificial saliva having a similar viral load to SARS-CoV-2 asymptomatic patients was inoculated inside the patient's phantom mouth. A 10 s-lasting dental procedure was performed using an aerosol-generating air-turbine, with or without high-volume evacuation (HVE). The effect of 0.5 vol% H2O2 cooling spray in reducing viral loads was tested. Viral presence on the operator phantom was assessed by Real-Time quantitative PCR on the mask's outer surface, on the phantom's forehead, and inside its mouth. Results: When the H2O2 cooling spray was used, as compared to the conventional spray, viral loads were significantly lower on all tested sites, falling below the detection limit. Viral loads did not significantly change in any tested site when HVE was used. Conclusion: The use of 0.5 vol% H2O2 cooling spray by dental handpieces drastically reduced the possibility of coronaviruses spread during aerosol-generating dental procedures. This strategy deserves further consideration among the preventive measures to be adopted during the SARS-CoV-2 pandemic.
Field experiments measuring the volatility of e-cig generated aerosols using a deep learning-enabled portable holographic microscope were conducted in a vape shop, showing a link between e-cig usage and the volatility...
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ISBN:
(数字)9781957171050
ISBN:
(纸本)9781665466660
Field experiments measuring the volatility of e-cig generated aerosols using a deep learning-enabled portable holographic microscope were conducted in a vape shop, showing a link between e-cig usage and the volatility of aerosols.
A wide-angle camera based imaging lidar was used to measure altitude dependent aerosol single angle side scattering. Aerosol extinction was derived for several continuous hours to monitor spatial and temporal distribu...
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ISBN:
(数字)9781957171050
ISBN:
(纸本)9781665466660
A wide-angle camera based imaging lidar was used to measure altitude dependent aerosol single angle side scattering. Aerosol extinction was derived for several continuous hours to monitor spatial and temporal distributions of boundary layer aerosols.
Continuous measurements of the near-surface black carbon (BC) aerosol mass concentration and columnar spectral aerosol optical depth (AOD) have been analyzed over rural and urban regions of peninsular India for the pe...
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ISBN:
(纸本)9781665462013
Continuous measurements of the near-surface black carbon (BC) aerosol mass concentration and columnar spectral aerosol optical depth (AOD) have been analyzed over rural and urban regions of peninsular India for the period of five years (2014 – 2018). The goal of this study is to gain a better understanding of the BC aerosols caused by anthropogenic emissions by using ground-based measurements from two different regions at the same time. Both regions exhibit similar monthly variations, however, annually, the urban region emits 2.5 times more BC aerosols. We found that urban activities account for the majority of roughly 50% of BC contributions. In addition, on weekdays BC levels are 20% higher than on weekends in the urban region. Furthermore, BC peaks in the morning and late evening with urban having a higher magnitude compared to rural region. One of the interesting findings is that even though surface-based BC mass concentration is 60% lower in the rural region, the AOD was almost similar in both regions, which could be attributed to the presence of elevated aerosol layers.
The presence of unfavorable meteorological conditions triggers pollution, and then further weakens turbulence, especially in the stable boundary layer (SBL), which is a frequent situation in heavy pollution episodes i...
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The presence of unfavorable meteorological conditions triggers pollution, and then further weakens turbulence, especially in the stable boundary layer (SBL), which is a frequent situation in heavy pollution episodes in China. The inapplicability of the classical Monin-Obukhov similarity theory and the uncertainty of the planetary boundary layer height can lead to large deviation of turbulent diffusion in the SBL in numerical simulations. However, in current mesoscale models, no term has been used to accurately describe the turbulent diffusion of aerosols. Therefore, we use the Mixing-Length theory to obtain the turbulent diffusion term of aerosols based on high-resolution observational data, and, for the first time, embed this term into a mesoscale model, which makes the turbulent diffusion process of aerosols more truly depicted. Results from a two-way coupled atmospheric-chemistry mesoscale model demonstrate that the turbulent diffusion term of aerosols can improve the problem of overestimated PM2.5 concentration in Eastern China.
Lightning activity is one of the global natural hazards that poses significant risks on human life and numerous aspects of the society's technological infrastructure. Understanding the linkage between aerosols pre...
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Lightning activity is one of the global natural hazards that poses significant risks on human life and numerous aspects of the society's technological infrastructure. Understanding the linkage between aerosols present in the atmosphere and lightning activity is important to further advance our knowledge of the global lightning activity cycle. The southwestern region of the Arabian Peninsula (AP) is home to one of the 500 hottest lightning spots in the world, and is not far from the largest contiguous sand desert in the world, the Empty Quarter (al-Rubea Al-Khali). Using data of individual lightning strokes from the the Global Lightning Detection Network (GLD360), in conjunction with remote sensing measurements of the aerosol optical depth (AOD) obtained at 500 nm from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra and Aqua satellites during active lightning days, we examine the evolution of lightning activity in two geographically and topologically different regions over the AP. One region extends inland to the desert (R1) and the other is in the southwest mountainous region that is close to the Red Sea (R2). In both regions, results from thunderdays-only indicate that lightning is strongly and positively correlated with the AOD loading, up to AOD similar to 0.8, after which the trend flattens or reverses direction. Results suggest the two opposite effects that aerosols could indirectly have on lightning activity are at play. Mountainous region exhibits much stronger linear relation compared to the inland region. Furthermore, both regions exhibit seasonal and asynchronous lightning activity and AOD loading. Year 2018 in R1 shows very high lightning activity, likely linked to the 2018 intense dust storms in the region.
Time series analyses and stochastic modeling assessments of aerosols are critical for climate change and human health studies. However, the precise characterization of the aerosol optical depth (AOD), its variability,...
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Time series analyses and stochastic modeling assessments of aerosols are critical for climate change and human health studies. However, the precise characterization of the aerosol optical depth (AOD), its variability, trends, and predictability, and its associated uncertainty at the global scale is largely unexplored. In addition, gaps in satellite-retrieved AODs across space and time remain an obstacle to accurately revealing aerosol properties. This study uses MODIS Collection 6 AOD retrievals for a time series analysis and modeling of global aerosols from 2003 to 2015. Random forest (RF) regression is first applied to replace the missing data in the satellite AOD retrievals. AOD variations and trends are then investigated and future values are predicted using a Mann-Kendall analysis approach and an autoregressive integrated moving average (ARIMA) model, respectively. The results indicate that the developed RF model enhances the AOD data coverage significantly, with the root mean square error and mean absolute error statistical metrics well below 0.13 and 0.08, respectively. High AOD loadings are found over East, South, and Southwest Asia, West and Central Africa, and northern South America. Prominent discrepancies are shown in aerosol variations and trends likely because of dust emissions, biomass burning, fossil fuel combustion, and socioeconomic practices, which has significant implications for climate systems and mitigation policy-making. The ARIMA model delineates AOD features with clear annual and seasonal variations and with high accuracy over most regions. The performance of the model is jointly impacted by the data quality and data values. Overall, our study suggests the feasibility and applicability of the RF model in reconstructing area-scale satellite missing AOD retrievals, as well as the ability of the stochastic ARIMA model to accurately depict and forecast AOD profiles. The globally simulated and predicted aerosols will improve evaluations of aeros
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