Kinds Of Aerosols Research Articles

Experimental assessment of counterfog bioaerosol fast sampler for virus detection and decontamination

The respiratory system is equipped with several defence mechanisms to protect the body from microorganisms and airborne pathogens. There are situations where the respiratory system can be overwhelmed or compromised and infection happens, especially in individuals with weakened immune systems. Airborne pathogens are a serious risk for human and animal health, as exemplified by the challenges faced during the COVID-19 pandemic. The list includes viruses of varying severity such as Influenza virus, SARS-CoV-2, measles virus, Varicella-Zoster Virus, or Respiratory syncytial virus among others. Smaller particles can remain suspended in the air for longer periods and may reach the lower respiratory tract, including the alveoli in the lungs. The real-time detection of these pathogens in the air presents a significant challenge. The aerosols, especially those carrying viruses, are so small that they often elude conventional air samplers, making it difficult both to detect their presence and to remove them effectively from the air. This work introduces a recent technique designed for rapid aerosol sampling, with a particular emphasis on virus sampling. The system underwent calibration using artificial ɸ29 virus aerosols and was subsequently tested with naturally emitted aerosols of SARS-CoV-2. A series of tests were conducted in diverse settings, including hospitals, farms, offices, and railway cars. The equipment is also capable of swiftly removing bioaerosols from the air, thereby facilitating effective decontamination. The relevance of this technology lies in its capability for swift detection and elimination of viruses and other kinds of aerosols from air, facilitating prompt decision-making during high-risk events.

Self-consistent Atmosphere Representation and Interaction in Photon Monte Carlo Simulations

We present a self-consistent representation of the atmosphere and implement the interactions of light with the atmosphere using a photon Monte Carlo approach. We compile global climate distributions based on historical data, self-consistent vertical profiles of thermodynamic quantities, spatial models of cloud variation and cover, and global distributions of four kinds of aerosols. We then implement refraction, Rayleigh scattering, molecular interactions, and Tyndall–Mie scattering to all photons emitted from astronomical sources and various background components using physics first principles. This results in emergent image properties that include: differential astrometry and elliptical point spread functions (PSFs) predicted completely to the horizon, arcminute-scale spatial-dependent photometry variations at 20 mmag for short exposures, excess background spatial variations at 0.2% due to the atmosphere, and a PSF wing due to water droplets. We use a common atmosphere representation framework to self-consistently model all phenomena by simulating individual photons. We reproduce the well-known correlations in image characteristics: correlations in altitude with absolute photometry (overall transmission) and relative photometry (spectrally dependent transmission), anticorrelations of altitude with differential astrometry (nonideal astrometric patterns) and background levels, and an anticorrelation in absolute photometry with cloud depth. However, we also find further subtle correlations including an anticorrelation of temperature with background and differential astrometry, a correlation of temperature with absolute and relative photometry, an anticorrelation of absolute photometry with humidity, a correlation of humidity with lunar background, a significant correlation of PSF wing with cloud depth, an anticorrelation of background with cloud depth, and a correlation of lunar background with cloud depth.

Analysis and Dynamic Monitoring of Indoor Air Quality Based on Laser-Induced Breakdown Spectroscopy and Machine Learning

The air quality of the living area influences human health to a certain extent. Therefore, it is particularly important to detect the quality of indoor air. However, traditional detection methods mainly depend on chemical analysis, which has long been criticized for its high time cost. In this research, a rapid air detection method for the indoor environment using laser-induced breakdown spectroscopy (LIBS) and machine learning was proposed. Four common scenes were simulated, including burning carbon, burning incense, spraying perfume and hot shower which often led to indoor air quality changes. Two steps of spectral measurements and algorithm analysis were used in the experiment. Moreover, the proposed method was found to be effective in distinguishing different kinds of aerosols and presenting sensitivity to the air compositions. In this paper, the signal was isolated by the forest, so the singular values were filtered out. Meanwhile, the spectra of different scenarios were analyzed via the principal component analysis (PCA), and the air environment was classified by K-Nearest Neighbor (KNN) algorithm with an accuracy of 99.2%. Moreover, based on the establishment of a high-precision quantitative detection model, a back propagation (BP) neural network was introduced to improve the robustness and accuracy of indoor environment. The results show that by taking this method, the dynamic prediction of elements concentration can be realized, and its recognition accuracy is 96.5%.

Mathematical Analysis of Pluviculture in the Frame of Caputo Fractional Derivative

Objectives: Climate change is a major issue the mankind is facing in the present scenario. This is a consequence of global warming that result in the change in temperature and rainfall over a long period of time. In this work, we analyze the fractional mathematical model projecting pluviculture. The Caputo fractional derivative is incorporated for better analysis of this event. Also, we discuss the boundedness, existence and uniqueness of the solutions of the proposed system. Sufficient conditions required for existence of asymptotic stability are discussed. Method: We have used the generalized Adams- Bashforth-Moulton predictor-corrector technique to solve the pluviculture model. It is the linear multistep implicit method used to solve the system of equations. Findings: It is established that, the intensity of precipitation is enhanced by introducing the aerosols to the water vapor. The incorporation of the fractional derivatives strengthens the model in a more realistic way. The influence of some parameters and fractional derivative on the rain making process are numerically analyzed. Novelty: The incorporation of Caputo fractional derivative to the pluviculture model along with the two kinds of aerosols is the novel in the model. Keywords: Pluviculture; Aerosol; Caputo fractional derivative; AdamsBashforthMoulton technique Mathematics Subject Classification: 26A33; 92D30

Analysis of hygroscopic growth properties of soluble aerosol under severe nuclear accidents conditions

Radioactive aerosol released under severe nuclear accidents conditions contains large amounts of soluble compounds. The hygroscopic growth of soluble aerosol enable to enlarge the particle size and affect the subsequent deposition behavior, which plays an important role on source term analysis. However, the investigation about hygroscopic growth properties of typical nuclear aerosol viz. Cesium iodine and cesium hydroxide, has been largely lacking and the hygroscopic model in MELCOR also need to validate and evaluate. In this paper, steady-state hygroscopic model based on Köhler theory was used to predict the hygroscopic growth factors of these two kinds of aerosols. Sensitivity analysis of surface tension and water activity of aqueous-solution droplet on hygroscopic growth factor were performed, and the prediction results were compared with the experimental data to evaluate MELCOR. The results show that the simplification of replacing surface tension of salt droplet with pure water in MELCOR is acceptable. The processing method of water activity in MELCOR overestimates the hygroscopic growth factors of cesium hydroxide, while its predictions are much close to the hygroscopic growth factors of cesium iodine. The improved model has higher prediction accuracy than MELCOR. In addition, the transient hygroscopic growth rate model was also used to analyze the effects of operating parameters on the hygroscopic growth characteristics of soluble aerosol. The hygroscopic growth rate is proportional to the relative humidity, particle size and gas temperature. Aerosol particles with larger initial size under higher relative humidity condition require longer time to attain equilibrium state, and the equilibrium time decreases with the increasing gas temperature. This study can provide theoretical reference for fundamental understanding of hygroscopic growth properties of soluble aerosol and the estimation of aerosol source terms under severe nuclear accidents conditions.

The Optical Properties of Aerosols at the Summit of Mount Tai in May and June and the Retrieval of the Complex Refractive Index

To study the optical properties of background atmospheric aerosols in East China, we carried out observations of the physical, chemical and optical properties of atmospheric aerosols at the summit of Mount Tai (Mt. Tai, 1533.7 m above sea level) from 13 May to 25 June 2017. The results show that the average scattering coefficient ( σ sca , 550 ) at 550 nm of the aerosols at the summit of Mt. Tai is 40.3 Mm−1, and the average absorption coefficient ( σ abs , 550 ) at 550 nm is 16.0 Mm−1. The complex refractive index of aerosols is a key parameter for aerosol retrieval and modeling. There are few studies on the equivalent complex refractive index of aerosol in the Taishan area. We calculated the aerosol equivalent complex refractive index using the observed aerosol scattering coefficients, absorption coefficients and particle size distribution data, providing more data support for future modeling in this region. The real part (n) of the complex refractive index at 550 nm of aerosol ranges from 1.31 to 1.98 (mostly under 1.50), with an average value of 1.38, while the imaginary part (k) ranges from 0.014 to 0.251 (less than 0.10 for over 95% samples), with an average value of 0.040. The analysis of the n and k of the aerosol average complex refractive index shows that the scattering properties of the aerosols at the summit of Mt. Tai are relatively weak and the absorption properties are relatively strong when compared with those of other kinds of aerosols. The k of the aerosol complex refractive index at the summit of Mt. Tai has strong correlations with the wind speed, temperature, as revealed by the correlation analysis.

Optimization of the MSMGWB model used for the calculation of infrared remote sensing signals from hot combustion gases of hydrocarbon fuel

To address the influence of initialization on the wavenumber subinterval grouping result and calculation accuracy of the multiscale multigroup wide-band k-distribution model (MSMGWB), an optimization platform was established to determine the best combination of grouping result and Gauss quadrature scheme. An optimization objective function was established based on weighted calculation errors of the MSMGWB model in 18 1D cases, in which radiance in the 3- to 5-µm wave band emitted by hot combustion gases of hydrocarbon fuel was attenuated by the atmosphere with various thermodynamic state parameters. A new initialization method for wavenumber subinterval grouping similar to the k-means++ algorithm was established to improve the efficiency of the optimization platform. The optimization result was evaluated using additional 1D cases with and without the influences of various kinds of aerosols in the atmosphere. Finally, evaluation results are presented on the calculation of remote sensing thermal images for a supersonic aircraft exhaust system and its hot jet. The results indicate that the optimized model has a higher calculation accuracy, better compatibility and lower computational cost compared with the original one.

Stochastic stability of aerosols-stimulated rainfall model

With increasingly erratic nature of monsoon, especially in Indian Ocean region clamors for artificial rain have gathering pace recently. For artificial rain, aerosols are used which act as cloud condensation nuclei (CCN) in the formation of cloud droplets from water vapors. In this paper, a nonlinear mathematical model is proposed and analyzed to increase the intensity of rain in the rain deficient regions using aerosols. To stimulate rainfall two kinds of aerosols are used. We have considered three different stages of water involved in the process of precipitation namely, (i) the density of water vapors, (ii) the density of cloud droplets, and (iii) the density of raindrops. Previously proposed models consist of a set of ordinary differential equations (ODE), whereas the use of stochastic differential equations (SDE) depicts more realistic situation as they include environmental disturbances. First, we propose a deterministic model and then convert it into a stochastic model by introducing white noise terms. We have found that the deterministic model is globally asymptotically stable without any condition, while the stability of stochastic model solely depends on the intensity of white noise.

Evaluation of relative impact of aerosols on photovoltaic cells through combined Shannon's entropy and Data Envelopment Analysis (DEA)

One of the biggest challenge before the world today is to find a trade-off between high energy demand and mitigation of greenhouse gas emissions. Researchers and energy policy makers around the world are now resorting to renewable energy (RE), as a solution to this crisis with special focus on solar energy, as it is the most abundantly available RE source. However, the requirement of high upfront capital investment is an inhibiting factor behind seamless deployment of solar energy technologies. Hence it is of paramount importance to increase the techno-commercial viability of the projects by leveraging on the environmental factors specific to project sites. In the present work, the impact of different kind of aerosols, which characterize different distinct geographical regions, on the performance of Photovoltaic (PV) cells have been investigated experimentally under different irradiation levels. The complex set of data generated by the experiment has been analysed and indexed by application of combined Shannon's entropy and Data Envelopment Analysis (DEA) to quantify the relative performance of the system under different environmental conditions, different TSPs at their different concentration levels. Through this work a comprehensive approach is proposed for the decision makers to enhance the techno-commercial viability of the PV projects.

CHANGES OF THE 2-STROKE AEROSOL IN THE EXHAUST SAMPLING SYSTEM

Nanoparticle emissions of two 2-stroke scooters were investigated along the exhaust- and CVS-system (Constant Volume Sampling) with closed and with open line (cone). Due to their technology, the scooters produce different kind of aerosol (state of oxidation & SOF-content) and in addition to that they were operated with and without oxidation catalyst. The scooters represent a modern technology with direct injection TSDI* ) (two stroke direct injection) and with carburettor.

Determination and Analysis on Flammability Grade of Two Kinds of Household Spray Aerosols Commonly Used in China

Most common household spray aerosols, such as insecticide aerosols and air freshener aerosols, are often regarded as same kind of products by many users. Flammable grades of the two kinds of spray aerosols most available in China were researched based on the tests of UN Recommendations of the Transport of Dangerous Goods - Model Regulations. According to the tests, though the two aerosols are both labeled with “Flammable” marks, insecticide aerosols sold in China, mostly can be classified as “Extremely Flammable” grade, and most air freshener aerosols are “Not Flammable”. Such research is benefit to the good manage of transportation, storage and usage for these two kinds of aerosol products.

Comparison of instruments for particle number size distribution measurements in air quality monitoring

Number size distributions of airborne particles are relevant to fields including ambient monitoring, pharmaceutical and automotive measurements. A number of commercially available instruments can be used to determine particle number size distributions including the Electrical Low Pressure Impactor (ELPI), Scanning Mobility Particle Sizer (SMPS), Fast Mobility Particle Sizer (FMPS) and the Aerodynamic Particle Sizer (APS). The comparability of the data provided by these instruments has not been fully tested for different kinds of aerosols. This study compared number size distributions of laboratory generated aerosols (TiO2, NaCl, fumed silica and soot) in a wind tunnel. Reasonable agreement was noted between the different instruments, though there were divergences. For example the ELPI was inconsistent at the upper and lower limits of its working size (at low concentrations). Instruments responded variably to different particle types, which has important implications for sampling heterogeneous particle mixtures such as those found in urban air. This study highlights the need for caution when comparing data obtained from different particle instruments, and demonstrates the requirement for further comparison studies in controlled settings using an assortment of particle types with the aim to standardise and harmonise particle sampling protocols.

Dependence of Precipitation Scaling Patterns on Emission Scenarios for Representative Concentration Pathways

AbstractPattern scaling is an efficient way to generate projections of regional climate change for various emission scenarios. This approach assumes that the spatial pattern of changes per degree of global warming (scaling pattern) is the same among emission scenarios. The hypothesis was tested for the scaling pattern of precipitation by focusing on the scenario dependence of aerosol scaling patterns. The scenario dependence of aerosol scaling patterns induced the scenario dependence of the surface shortwave radiation scaling pattern. The scenario dependence of the surface shortwave radiation scaling pattern over the ocean tended to induce the scenario dependence of evaporation scaling patterns. The scenario dependence of evaporation scaling patterns led to the scenario dependence of precipitation scaling patterns locally and downwind. Contrariwise, when the scenario dependence of aerosol scaling patterns occurred over land, the scenario dependence of surface shortwave radiation scaling patterns induced the scenario dependence of the scaling patterns of evaporation, surface longwave radiation, and sensible heat. Consequently, the scenario dependence of evaporation scaling patterns was smaller over land, and the scenario dependence of precipitation scaling patterns tended to be insignificant. Moreover, the scenario dependence of the southern annular mode and polar amplification caused some of the scenario dependence of precipitation scaling patterns. In this study, only one global climate mode was analyzed. In addition, sensitivity experiments that remove aerosol emissions from some regions or some kinds of aerosols are ideal to separate the impacts of aerosols. Thus, an analysis of the dependencies of precipitation scaling pattern among global climate models and the sensitivity experiments are required in future work.

Role of mineral dust, soot, and bacteria in cloud and precipitation formation processes over Indian subcontinent using an atmospheric general circulation model

An aerosol-type specific heterogeneous nucleation parameterization that based on the classical nucleation theory has been implemented into the atmospheric general circulation model (AGCM), ECHAM5. The microphysical responses in precipitation formation to the variation of ice nuclei (IN) species over Indian subcontinent were analyzed using AGCM, considering the immersion freezing nucleation from mineral dust, dust with ammonium sulfate coating, soot and bacteria species. Immersion freezing by bacteria species is found to be dominating in October–December, whereas dust with ammonium sulfate produces more cloud ice in January–March. There are very little differences in cloud ice formation during April–May and June–September among various IN species. There is also a geographic dependence in the role of different IN species in precipitation formation, like bacteria is important in Southern Peninsula and dust particles play a significant role in central India. In nature the emission of ice nucleating active bacteria and non-biological dust, soot into the atmosphere is important and highly dependent on temperature, and precipitation. So it is the worthy of investigation on the role of different kind of aerosols on the microphysics and precipitation processes, the biosphere–atmosphere interaction and climatic research.

Study of cloud microphysical properties over India during CAIPEEX using a mesoscale model with new cloud microphysical scheme—Part I

Incorporation of aerosol interaction in cloud microphysics is being the central issue now a day. In the present study, an improved and modified cloud microphysical scheme comprising bulk-formula two-moment mixed-phase cloud scheme has been incorporated with a regional model to study the cloud–aerosol interaction in the mixed-phase cloud system. The paper intends to sensitivity study as to what extent this new microphysical scheme can capture the observed cloud microphysical properties. The observed cloud microphysical hydrometeors are evaluated from MODIS (Moderate Resolution Imaging Spectrometer) and CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement EXperiment) data set over the Indian peninsular region. Surface accumulated precipitation is collected from TRMM-3B42 data sets. One active convection (case study 1) and two suppressed convection events (case study 2 and case study 3) during Indian south west monsoon are simulated over three different locations of the Indian peninsular region with the help of a multi nested mesoscale model based on microphysical modification. The cloud microphysical properties such as cloud water path from satellite data retrieval and cloud drop number concentration, cloud droplet radius from CAIPEEX, are reproduced well by the modified microphysical scheme. The rainfall is also reasonably well simulated during active monsoon convection event (6th July, 2009) as well as suppressed monsoon convection events (15th June and 19th August, 2009). Moreover, another sensitivity experiment is done to include natural aerosols, like dust as a representation of heterogeneous ice nucleation. The inclusion of mineral dust effect as ice nuclei provides realistic cloud microphysical properties during present case studies successfully. So it is a worthy investigation of the role of different kinds of aerosols on the microphysics and precipitation processes.

Measurement and Statistic Analysis of Combustion Heat of Two Kinds of Household Spray Aerosols in China

Abstract High volatility makes it difficult to measure the combustion heat of spray aerosols’ content. However, calorific value is a precondition to grade the fire hazard classification of aerosol products according to UN Recommendations of the Transport of Dangerous Goods -Model Regulations. With auxiliary of empty medical capsule, injector and adhesive tape, etc., a series of combustion heat tests on some household aerosol products including insecticide aerosol and air freshener aerosol products sold in China were completed with a commercial oxygen bomb calorimeter. The confidence interval of different kinds of aerosols’ combustion heats were researched at 95% confidence level. The results show that the confidence interval range of combustion heat of insecticide aerosol is from 43359 J/g to 49911 J/g, higher than 20 kJ/g, which is the critical quota to determine the flammability of aerosol products. The heat of air freshener aerosols are less than one-tenth of insecticide aerosols, which is from 2743 J/g to 3430 J/g. According to the UN regulation, insecticide aerosol products at least belong to the flammable ones at 95% confidence level, and the air freshener aerosol products are relatively safe on the characteristic of fire risk.

The Suitability of the IOM Foam Sampler for Bioaerosol Sampling in Occupational Environments

Concurrent samples were collected with Andersen and IOM foam samplers to determine whether if the IOM foam sampler can be applied to collect culturable microorganisms. Two different kinds of aerosols were studied: peat dust in a power plant and mist from coolant fluid aerosolized during grinding of blades and rollers in a paper mill. In the power plant, the concentrations of fungi were 2–3 times higher in the IOM samples than in the Andersen samples. However, more fungal genera were identified in the latter case. The methods yielded similar concentrations of bacteria and actinobacteria in the power plant. On the other hand, the performance of the IOM foam sampler was very poor in the paper mill, where stress-sensitive gram-negative bacteria dominated; low concentration of bacteria was detected in only one IOM sample even though the concentration of bacteria often exceeded even the upper detection limit in the Andersen impactor samples. It could be concluded that the IOM foam sampler performs quite well for collecting inhalable fungi and actinobacteria. However, the Andersen sampler provides better information on fungal genera and concentrations of gram-negative bacteria. Personal sampling with the IOM foam sampler provided an important benefit in the power plant, where the concentration ratio of personal to stationary samples was much higher for bacteria than for inhalable or respirable dust.

Filtration of Bioaerosols Using Fibrous Air Filter Media

Airborne microorganisms cause many serious health problems. To control contamination and achieve acceptable indoor air quality (IAQ), it is necessary to study air filtration of bioaerosols systematically. The authors of this paper designed a test system to determine the removal efficiencies of fibrous air filter media for traditional nonbiological airborne particles (Dioctylphthalate, polystyrene latex, etc.) and bioaerosols. Escherichia coli and Serratia marcescens, generated by a Collison nebulizer, were used as two microbiological markers in evaluating the filtration efficiencies of air filter media. The removal efficiencies for challenge bioaerosols were compared with those of nonbiological particles of the same aerodynamic diameter. The efficiencies for the two kinds of aerosols were found to have similar characteristics, with the efficiency for the former generally found to be a little higher. A formula of a proposed filtration model for bioaerosols is suggested to roughly predict the filtration performance of the air filter medium. According to the experimental results, medium efficiency air filters are suitable for filtering biological particles in air-handling units. The filter efficiency measured with dioctylphthalate particles of 1 μm is useful for predicting the removal efficiency of bioaerosols for the filter medium.

Atmospherically deposited major and trace elements in the winter snowpack along a gradient of altitude in the Central Pyrenees: The seasonal record of long-range fluxes over SW Europe

The chemistry of high mountain snowpacks is a result of the long-range atmospheric transport and deposition of elements. Pyrenean snowpacks contain information about the fluxes of elements over SW Europe in winter. Here we analysed Al, Ti, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb in the 2004–05 winter snowpack in the Central Pyrenees, at an altitude range of 1820–3200 m a.s.l. Ni, As, Se and Cd were not detected in most cases. The concentrations of the remaining elements were comparable to those found in other high mountain areas in Europe and North America considered representative of regional background of atmospheric deposition in populated areas. In contrast, our measurements were higher than those of polar areas, which represent the global background. Single measurements of concentrations and snow accumulation were subject to considerable spatial variability, which may be attributable to strong wind drift and other post-depositional processes. The major ions chemistry of the snow indicated three possible origins for the solutes: terrigenous dust, sea salt spray and polluting S and N aerosols. We found no association between Cu, Zn and Pb and any of these possible sources. This observation therefore indicates that these elements were not preferentially bound to any particular kind of aerosol. Snow collected at altitudes of up to 2050 m a.s.l. presented higher concentrations of several elements than snow above this altitude, thereby indicating a local influence. Snow collected above 2300 m a.s.l. was therefore more representative of broad regional inputs. At these higher altitudes, snow was not enriched in Al, Ti, Mn, Fe or As compared with the composition of the upper continental crust and the local lithology, and these elements (except Mn) appeared almost exclusively in the particulate fraction. This observation indicates that Al, Ti, Mn, Fe and As were present mainly as part of dust particles of terrigenous origin. In contrast, Cu, Zn, and Pb presented medium to high enrichment factors and showed a higher proportion of soluble forms, thereby indicating their polluting character.

Virological investigation on aerosol from waste depuration plants.

Aerosol from activated mud decontamination plants used for the treatment of urban sewage can represent a vehicle for bacteria, virus and fungi. As a result, they become an infective hazard for plant personnel, the general population residing in the surrounding area and the occasional visitor. The present investigation focuses on the identification of enteric-type viruses in this kind of aerosol. The following methods were employed on 214 samples collected in the 1999-2000 period: cell culture (BGM, RD, Hep-2), electron microscopy, and polymerase chain reaction (PCR). Cytopathic effect was mild in 180 samples, and severe in 14, upon their first passage in culture. Virus identification was based on positivity to both electron microscopy (EM) and PCR. Thus, one positive sample was recognized to be of enteric-type virus and two positive samples were recognized as reovirus-type. All samples were negative for Norwalk-type virus or HAV. There was considerable discrepancy between electron microscopy and PCR concerning the number of enteric-type viruses recognized. A possible explanation is contamination with animal-type enterovirus.