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• A novel preparation method of kapok filter paper with an excellent sheet formation. • A novel energy-efficient kapok filter paper with high DHC for solid-oil mixed aerosol. • Hollow lumen and oleophilic characteristic facilitate the filtration of oily aerosol. • Loading behavior evolution over oil content is subject to deposition behavior. • A particle deposition mechanism is proposed to explain loading behavior evolution. Although typical high efficiency filter media for gas turbine exhibit short lifespan under harsh conditions with excessive oily aerosol, rare literatures are available concerning fundamental reason or introducing filter media for addressing aforementioned conditions. Herein, we developed a novel kapok filter paper with high energy-efficiency and dust holding capacity (DHC) against solid-oil mixed aerosol. Loading behavior of filter media was characterized in terms of both macroscopic loading behavior (pressure drop and DHC evolution over oil content) and micro-scale particle deposition behavior. Owing to hollow lumen and waxy surface of kapok fiber, the novel filter paper was fluffy and oleophilic, which made it outperform typical commercial filter media (F01 and F02) in energy saving and DHC. Under harshest conditions where F01 and F02 manifested low DHC of 8.0 g/m2, 13.3 g/m2 and 29.1 g/m2, 34.7 g/m2 at the oil content of 50%, 75%, respectively, the kapok filter paper owned notably excellent DHC of 160.5 g/m2, 240.8 g/m2, respectively. Moreover, it was revealed that loading behavior evolution (resulted from the increase of oil content) was subject to deposition behavior. Once oil content was above 25%, pressure drop profiles transitioned from that of solid particles loading to that of liquid particles loading. Depositions structure varied from well-defined particles to particles-in-oil with films covered. Due to formation of a porous structure, a critical maximum DHC occurred for mixed aerosol with 25% oil content. Finally, a particle deposition mechanism was proposed, for the first time, to explain the loading behavior evolution over oil content. [ABSTRACT FROM AUTHOR]

Nebulising liquid samples and using the aerosol thus obtained for further analysis is the standard method in many current analytical techniques, also with inductively coupled plasma (ICP)-based devices. With such a set-up, quantification via external calibration is usually straightforward for samples with aqueous or close-to-aqueous matrix composition. However, there is a variety of more complex samples. Such samples can be found in medical, biological, technological and industrial contexts and can range from body fluids, like blood or urine, to fuel additives or fermentation broths. Specialized nebulizer systems or careful digestion and dilution are required to tackle such demanding sample matrices. One alternative approach is to convert the liquid into a dried solid and to use laser ablation for sample introduction. Up to now, this approach required the application of internal standards or matrix-adjusted calibration due to matrix effects. In this contribution, we show a way to circumvent these matrix effects while using simple external calibration for quantification. The principle of representative sampling that we propose uses radial line-scans across the dried residue. This compensates for centro-symmetric inhomogeneities typically observed in dried spots. The effectiveness of the proposed sampling strategy is exemplified via the determination of phosphorus in biochemical fermentation media. However, the universal viability of the presented measurement protocol is postulated. Detection limits using laser ablation-ICP-optical emission spectrometry were in the order of 40 μg mL − 1 with a reproducibility of 10 % relative standard deviation (n = 4, concentration = 10 times the quantification limit). The reported sensitivity is fit-for-purpose in the biochemical context described here, but could be improved using ICP-mass spectrometry, if future analytical tasks would require it. Trueness of the proposed method was investigated by cross-validation with conventional liquid measurements, and by analyzing IAEA-153 reference material (Trace Elements in Milk Powder); a good agreement with the certified value for phosphorus was obtained. [ABSTRACT FROM AUTHOR]

Conventional airborne virus measurement usually requires appreciable sampling and detection times. Viral aerosols should also be collected or prepared in a liquid medium whose volume typically ranges from milliliters to tens of milliliters; hence, many sampling and detection steps need to be taken with the unit horizontal or immobile. Moreover, viral aerosols need to be sufficiently enriched, which makes real-time monitoring difficult. Herein, we present a near real-time enrichment and quantification system of airborne viruses that consists of a wet-paper-based electrochemical immunosensor with a gel electrolyte and a modified electrostatic particle concentrator. A small amount of phosphate-buffered saline flowed on the electrode, which resulted in sensor electrodes that are barely wet (covered in a thin buffer film measuring several micrometers) to ensure antigen–antibody interaction and the removal of non-target particles on the electrode surface. This system ensures that airborne viruses are highly enriched on the working electrode of the immunosensor, and it is possible to measure the MS2 virus particle concentrations every 10 min for 60 min stably and selectively against non-target airborne viruses and bacteria at horizontal and tilted measurement configurations. This system thus has the potential to be used in the real-time mobile monitoring of airborne microorganisms. [Display omitted] • Wet-paper-based electrochemical immunosensor under an electrostatic field is used to sample and quantify airborne viruses. • The sensors are barely wet to ensure antigen-antibody interaction and the removal of non-targets. • The enrichment ratio for airborne viruses is very high (> 108). • Airborne viruses are sampled and stably measured every 10 min for 60 min. • Airborne viruses are measured selectively against non-targets even when the unit is tilted. [ABSTRACT FROM AUTHOR]

This technical note documents the use of paper as electrospray emitters. The porous structure of the paper automatically delivers the liquid by capillary effects without the need of a mechanical pump. The liquid flow rate can be approximately quantified using Washburn equation. Despite the limited durability, paper-based electrospray emitters exhibit unique features such as ease of multiplexing, self-regulated liquid supply without need of pumps, ultra-low cost, and versatility provided through origami. [ABSTRACT FROM AUTHOR]

The functionalized soft materials are widely used in the field of flexible electronics devices, but there are still some challenges in preparing functionalized paper with sensitive reaction. In this paper, the functionalized paper with asymmetric wettability was developed by introducing nitrocellulose (NC) and multi-walled carbon nanotubes (MWCNTs) into the paper surface. This asymmetric wettability gives the paper sensitivity to relative humidity. When functionalized paper is placed in humid environment, CNTs can be folded and unfolded correspondingly in normal and reverse bending, which leads to the change of resistance on the paper surface. Therefore, the functionalized paper shows the induction to humidity factor through such bending deformation and resistance change. Interestingly, this paper can be further applied to flexible sensors for monitoring the relative humidity and breathing steam of various soils. In addition, the modifier and matrix are non-toxic, harmless and environmentally friendly, the preparation method of the coating is simple, and the functional paper can be reused for many times, which makes it possible for the functional paper to be applied in practice. We proposed a strategy of constructing hydrophobic layer on hydrophilic printing paper with hydrophobic multi-walled carbon nanotubes and nitrocellulose by a simple coating method. The functional paper can respond to the curvature and resistance of water mist due to the water transportation imitating Mimosa pudica. [Display omitted] • The prepared functional paper has asymmetry of hydrophobicity/hydrophilicity. • The prepared functional paper still has excellent resistance to water after repeated many times. • The paper can make resistance response to water in various states (continuous liquid water, wet airflow and wet air). • The experiment is nontoxic, harmless, environmentally friendly and simple. [ABSTRACT FROM AUTHOR]

Pesticides are largely used at worldwide level to improve food production, fulfilling the needs of the global population which is increasing year by year. Although pesticides are beneficial for crop production, their extensive use has serious consequences for the pollution of the produced food as well as for soil and groundwaters. Indeed, it is reported that 50% of sprayed pesticides reach different destinations other than their target species, including soil, surface waters, and groundwaters. For this reason, we developed a flower-like origami paper-based device for pesticides detection in aerosol phase for precision agriculture. In detail, the paper-based electrochemical platform detects paraoxon, 2,4-dichlorophenoxyacetic acid, and glyphosate at ppb levels by measuring their inhibitory activity towards three different enzymes namely butyrylcholinesterase, alkaline phosphatase, and peroxidase enzyme, respectively. This integrated electrochemical device is composed of three office paper-based screen-printed electrodes and filter paper-based pads loaded with enzymes and enzymatic substrates. The pesticide detection is carried out by measuring through chronoamperometric technique the initial and residual enzymatic activity by using a smartphone-assisted potentiostat and evaluating the percentage of inhibition, proportional to the amount of aerosolized pesticides. This paper-based device was able to detect the three classes of pesticides in aerosol phase with limits of detection equal to 30 ppb, 10 ppb, and 2 ppb, respectively for 2,4-D, glyphosate, and paraoxon. [Display omitted] • Paper-based flower like biosensor for pesticide detection. • Pesticide multiclass analysis using origami paper-based devices. • Smartphone paper-based devices for boosting precision agriculture. [ABSTRACT FROM AUTHOR]

• Paper-based electrochemical sensors for hydrogen peroxide in aerosol phase. • Filter screen-printed electrode modified via drop casting with nanocomposite. • Electrochemical smartphone-assisted device to customize the disinfection process. The outbreak of COVID-19 is caused by high contagiousness and rapid spread of SARS-CoV-2 virus between people when an infected person is in close contact with another one. In this overall scenario, the disinfection processes have been largely improved. For instance, some countries have approved no-touch technologies by vaporizing disinfectants such as hydrogen peroxide, with the overriding goal to boost the safety of the places. In the era of sustainability, we designed an electrochemical paper-based device for the assessment of hydrogen peroxide nebulized by a cost-effective ultrasonic aroma diffuser. The paper-based sensor was fabricated by modifying via drop-casting a filter paper-based screen-printed electrode with a dispersion of carbon black-Prussian Blue nanocomposite, to assess the detection of hydrogen peroxide at −0.05 V vs Ag/AgCl. The use of paper-based modified screen-printed electrode loaded with phosphate buffer allowed for monitoring the concentration of hydrogen peroxide in aerosol, without any additional sampling instrument to capture the nebulized solution of hydrogen peroxide at a concentration up to 7% w/w. Hydrogen peroxide, a reconverted ultrasonic aroma diffuser, and the paper-based electrochemical sensor assisted by smartphone have demonstrated how different low-cost technologies are able to supply an useful and cost-effective solution for disinfection procedures. [ABSTRACT FROM AUTHOR]

• Fast separation of 18 analytes (color developers, sensitizers, dyes) in 10 min. • Quantification without references via UV chromophore concentration and Corona CAD. • Analysis of 211 thermal paper samples from the German market 2018/2019. • Determination of color developers as functional components (> 0.02 wt%). • Color developers Pergafast 201, BPA, BPS, D8, BPS-MAE, D-90, TGSA. Thermal papers (e.g. point of sale receipts, adhesive labels, tickets) significantly contribute to contamination of paper material cycles and the environment with substances of (eco-) toxicological concern. In particular, they contain color developers like endocrine disrupting bisphenols in typical concentrations of about 1–2 percent per weight (wt%). Bisphenol A (BPA) was used as the common color developer over the last decades, but it will be restricted for thermal paper application in the European Union to a limit of 0.02 wt% from 2020 onwards. Consequently, a variety of BPA substituents such as bisphenol S (BPS) and its derivatives gain importance in thermal paper application. In this study, a rapid, reliable and cost-effective method for identification and quantification of BPA, alternative color developers and related substances like sensitizers is presented based on HPLC separation coupled with diode array detection (DAD) and Corona charged aerosol detection (CAD). Quantification was performed with regard to the intended use of the substances in thermal papers. Besides traditional UV external calibration using reference standards, alternative quantification approaches, in particular UV chromophore concentration for BPS derivatives and CAD universal response technique for low-volatile color developers, were applied and compared in order to allow quantification without reference substances. A market analysis for intended used color developers and sensitizers was performed on thermal paper samples (n = 211) collected in Germany during 2018 and 2019. Pergafast 201 (in 41.7% of the samples) was the most common color developer with concentrations above 0.02 wt%, followed by BPA (36.0%), BPS (13.3%) and other BPS derivatives known as D8, D-90, BPS-MAE and TGSA, that are mainly present in adhesive labels. Sensitizers were determined in over 90% of the samples. [ABSTRACT FROM AUTHOR]

[Display omitted] Aerosols greatly influence precipitation characteristics, thereby impacting the regional climate and human life. As an indispensable factor for cloud formation and a critical radiation budget regulator, aerosols can affect precipitation intensity, frequency, geographical distribution, area, and time. However, discrepancies exist among current studies due to aerosol properties, precipitation types, the vertical location of aerosols and meteorological conditions. The development of technology has driven advances in current research, but understanding the aerosol effects on precipitation remain complex and challenging. This paper revolves around the following topics from the two perspectives of Aerosol-Radiation Interaction (ARI) and Aerosol-Cloud Interaction (ACI): (1) the influence of different vertical locations of absorbing/scattering aerosols on the atmospheric thermal structure; (2) the fundamental theories of ARI reducing surface wind speed, redistributing water vapour and energy, and then modulating precipitation intensity; (3) different aerosol types (absorbing versus scattering) and aerosol concentrations causing different precipitation diurnal and weekly variations; (4) microphysical processes (cloud water competition, invigoration effect, and evaporation cooling) and observational evidence of different effects of aerosols on precipitation intensity, including enhancing, inhibiting, and transitional effects from enhancement to suppression; and (5) how meteorology, water vapor and dynamics influencing the effect of ACI and ARI on precipitation. In addition, this review lists the existing issues and future research directions for attaining a more comprehensive understanding of aerosol effects on precipitation. Overall, this review advances our understanding of aerosol effects on precipitation and could guide the improvement of weather and climate models to predict complex aerosol-precipitation interactions more accurately. [ABSTRACT FROM AUTHOR]

The reader will come to appreciate how aerosol drug delivery to children depends on: • Selecting the right device, • Selecting the right interface, • Educating the patient and parents effectively • Optimizing patient adherence to therapy in children. Pulmonary drug delivery is complex due to several challenges including disease-, patient-, and clinicians-related factors. Although many inhaled medications are available in aerosol medicine, delivering aerosolized medications to patients requires effective disease management. There is a large gap in the knowledge of clinicians who select and provide instructions for the correct use of aerosol devices. Since improper device selection, incorrect inhaler technique, and poor patient adherence to prescribed medications may result in inadequate disease control, individualized aerosol medicine is essential for effective disease management and control. The components of individualized aerosol medicine include: (1) Selecting the right device, (2) Selecting the right interface, (3) Educating the patient effectively, and (4) Increasing patient adherence to therapy. This paper reviews each of these components and provides recommendations to integrate the device and interface into the patient for better clinical outcomes. [ABSTRACT FROM AUTHOR]

The aerosol particles present in the atmospheric region mainly affect the climate radiative forcing directly by scattering & absorbing the sunlight. Also, it indirectly influences the formation of clouds, precipitation and acts as a considerable uncertainty in assessing Earth's radiation budget. Determination of aerosol type is significant in characterizing the aerosol role in the atmospheric processes, feedback, and climate models. This paper proposes two aerosol classification models, one based on the source and another based on the composition, to classify the aerosols using aerosol optical properties. The source based aerosol classification method helps to identify the sources which cause pollution in a particular region. Based on the results, proper control measures can be taken to reduce pollution. The composition based aerosol classification helps to identify the nature of aerosol types, such as absorbing or non-absorbing. This classification helps to study the climate of the Kanpur region. The aerosol data is taken from AERONET (AErosol RObotic NETwork) for the period 2002–2018 for the Kanpur region. The composition based aerosol classification model uses Single Scattering Albedo (SSA), Angstrom Exponent (AE), and Fine Mode Fraction (FMF) parameters to categorize aerosols based on their composition. The source based aerosol classification model classifies the aerosols based on values of AE and Aerosol Optical Depth (AOD) and describes the source of the aerosol particles. Knowledge of aerosol sources and compositions helps execute policies or controls to reduce aerosol concentrations. Machine learning algorithms, Naïve Bayes, K Nearest Neighbor, Decision Tree, Support Vector Machine, and Random Forest are used to validate classification schemes. The performance analysis of machine learning algorithms is compared using ten different metrics, and the results are also compared with the existing aerosol classification models. The results of the classification show that the source based aerosols of the desert and arid background and the composition based aerosols of types, Mixture Absorbing, Coarse absorbing (Dust), and Black Carbon are dominant over the Kanpur region during the study period considered. The Number of non-absorbing (scattering) type aerosols are least in the study region considered during the study period at all the seasons. It is found that the Random Forest and Decision Tree models outperform the other machine learning models considered and the existing classification models in terms of accuracy (99.55 %) and other performance metrics considered. [ABSTRACT FROM AUTHOR]

3-methylcatechol (3MC) is a molecule of environmental interest due to its presence in the atmosphere during biomass burning events, leading to the formation of secondary organic aerosols. This paper goes one step further than the paper from A.S. Hazrah et al. (2022) [10]. A three-dimensional torsional potential energy surface was determined, confirming the existence of three rotamers for 3MC. One dimensional potential energy curves along the rotation of the methyl group were computed and fitted to estimate the barrier height in each conformer. Experiments were performed at low temperature in the microwave domain (2 − 20 GHz range) and, for the first time, in the millimeter-wave domain (70 − 110 GHz range) at T = 323 K with a specially designed heated absorption cell. The rotational linelist was fitted to provide updated spectroscopic parameters for the two 3MC conformers of lowest energies. In particular, the A − E splitting is observed in the microwave region for both conformers while in the millimeter-wave region, it is only seen for the conformer of the lowest energy. • Three-dimensional scan of the torsional potential with density functional theory. • Heated absorption cell for low vapor pressure of semi-volatile organic compounds. • First recording of the 3-methylcatechol spectrum in the millimeter-wave domain. [ABSTRACT FROM AUTHOR]

Particulate matter (PM), one of the major air pollutants, is generated by variety of natural or man-made sources, leading to acute and chronic diseases in humans since the last few decades. Employing satellite-derived aerosol optical depth (AOD) data, a wide technique that allows the retrieval of the PM concentration to support diverse on-field applications, including eliminating regular monitor stations and enhancing quality of breathing air. In this current review, the collection of data like ground-level particulate matter concentration, AOD, and metrological data, along with data screening, model grid and grid alignment, have been discussed. This paper endeavours the various development of models like single-stage, multi-stage, hierarchical, and ensemble models for PM prediction. Furthermore, the multicollinearity problem in developing the optimization model has been addressed. In order to evaluate the model efficiency, different performance evaluation techniques have been explored. Finally, the paper presents future directions for PM retrieval with the help of AOD data, such as the need for increased spatial and temporal resolution satellite data, incorporating more sophisticated machine learning models, and developing a global PM product from satellite AOD. The present review also accentuated the determination of PM in the air, which might be advantageous for the environment and human beings. • Satellite-derived aerosol optical depth (AOD) data is used to retrieve PM concentration for on-field applications. • Data collection, screening, model development, and performance evaluation for PM prediction were discussed. • Parameter selection considerations. • Delineates PM retrieval from AOD and summarize the various models used for retrieving PM. • Future directions for PM retrieval using AOD data with machine learning models. [ABSTRACT FROM AUTHOR]

Characterization of the onset of combustion reactions within organic materials, such as the tobacco in tobacco products, is very complex. Such materials are commonly used as a porous matrix and the combustion reactions, if present, are generally heterogeneous in nature and compete with drying, vaporization, endothermic and exothermic pyrolysis, as well as assisted exothermal degradation. Fundamental approaches towards the characterization of the onset of combustion reactions are not well established and therefore the literature only provides information that can be used as signatures that aim to reflect the presence or absence of a combustion reaction. These signatures many times link characteristic emissions to specific temperature bands in the organic material assuming local thermal equilibrium between solid and gas phases. This paper presents a review of the literature that reports on the characterization of ignition of heterogeneous combustion within porous combustible materials and the processes commonly associated with thermal degradation and combustion. The review covers emissions and other signatures that aim to establish the onset of heterogeneous combustion, and while the discussion remains general, this review focuses on the evidence that serves to differentiate thermal degradation from the onset of combustion of tobacco products. The literature shows consistency in that below a characteristic temperature of 400 °C, thermal degradation of the tobacco in tobacco products is net endothermic, the formation of products that can be related to oxidation is limited, yields of polycyclic aromatic hydrocarbons (PAHs) are negligible and atmospheric oxygen has very limited influence on the degradation chemistry. Furthermore, the reactions leading to the conversion of PAHs into soot do not occur until much higher temperatures. Therefore, the characteristic signatures associated to the effluent released below a characteristic temperature of 400 °C consist of gaseous compounds and liquid droplets. These liquid-based aerosols are fundamentally different from the carbonaceous soot particles that represent a characteristic signature of combustion. Moreover, an extensive review of the effluent of heated tobacco products during operation establishes that the effluent exhibits the signatures of liquid-based aerosols and does not show the characteristic signatures of combustion processes. • This paper reviews the literature that characterizes the onset of combustion reactions within organic materials, such as the tobacco in tobacco products. • Literature review on fundamental approaches towards the characterization of the onset of combustion reactions. • Information that can be used as signatures that aim to reflect the presence or absence of a combustion reaction. • Signatures that many times link characteristic emissions to specific temperature bands in the organic material are presented. • The review covers emissions and other signatures that aim to establish the onset of heterogeneous combustion, and while the discussion remains general, this review focuses on the evidence that serves to differentiate thermal degradation from the onset of combustion of tobacco products. [ABSTRACT FROM AUTHOR]

Effective evaluation and prediction of aerosol transport deposition in the human respiratory tracts are critical to aerosol drug delivery and evaluation of inhalation products. Establishment of an in vitro - in vivo correlation (IVIVC) requires the understanding of flow and aerosol behaviour and underlying mechanisms at the microscopic scale. The achievement of the aim can be facilitated via computational fluid dynamics (CFD) based in silico modelling which treats the aerosol delivery as a two-phase flow. CFD modelling research, in particular coupling with discrete phase model (DPM) and discrete element method (DEM) approaches, has been rapidly developed in the past two decades. This paper reviews the recent development in this area. The paper covers the following aspects: geometric models of the respiratory tract, CFD turbulence models for gas phase and its coupling with DPM/DEM for aerosols, and CFD investigation of the effects of key factors associated with geometric variations, flow and powder characteristics. The review showed that in silico study based on CFD models can effectively evaluate and predict aerosol deposition pattern in human respiratory tracts. The review concludes with recommendations on future research to improve in silico prediction to achieve better IVIVC. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new method to invert the complex refraction index (CRI) and particle morphology of non-spherical aerosols based on the full Stokes parameters of non-spherical aerosols is proposed. • The method has fewer limitations, and does not need to assume a function to describe the aerosol size distribution. It can invert the CRI and particle morphology for unknown non-spherical aerosol particles accurately. • A new Stokes parameters measurement system for non-spherical aerosol particles is designed. The full Stokes parameters and backscattering matrix of dust aerosols particles are measured and inverted. • The light scattering parameters calculated by the full Stokes parameters can be used for fine classification of particles of different morphology. The complex refraction index (CRI) and particle morphology of aerosols are the most important microphysical parameters of aerosols. They are related to the light scattering parameters of aerosols closely. However, the variation of polarization state of light scattering parameters of non-spherical particles is very sensitive to the CRI and particle morphology. In order to accurately obtain the CRI and particle morphology of non-spherical aerosols, a new method of inversion the CRI and particle morphology for non-spherical aerosols using the full Stokes parameters of non-spherical aerosols is proposed. In this paper, a new Stokes parameters measurement system for non-spherical aerosol is designed. The backscattering (180°) full Stokes parameters of the typical non-spherical aerosol (dust aerosol particle population) are measured. The CRI value of dust aerosols estimated using this method is consistent with those of the references. The feasibility of our retrieval method is confirmed. In this paper, the relationship between the dust aerosol CRI and the change of particle size during the dust settling process is investigated. The results show that the average CRI of dust aerosol does not vary with the particle size distribution in settling process. At the same time, the linear depolarization ratio and the ellipticity of backscattered polarized light of the dust aerosol particles are calculated using the full Stokes parameters. It is found that the non-spherical aerosol linear depolarization ratio and the ellipticity of backscattering polarized light are very sensitive to particle morphology. They can be used for fine classification of particles of different morphology in the dust aerosol particle population. [ABSTRACT FROM AUTHOR]

In the process industries, the flammable and explosive hazards of aerosols receive less attention and have less understanding as compared to gases and dust clouds. Numerous incidents in various industries have revealed the distinct differences between the hazards of a bulk liquid compared to those of aerosols. Flash point, the criterion for liquid flammability becomes insignificant when the liquid is present in aerosol form. A practical discussion of the criteria for aerosol flammability hazard assessment is needed. Unlike standard measurements for gas and dust clouds, an aerosol flammability standard test method, such as ASTM D3065−01, has not been widely adopted owing to the lack of quantification. Therefore, it is important to establish quantitative aerosol flammability and aerosol explosion testing procedures. This paper comprehensively reviews the methodologies to generate aerosols, both lab and large-scale aerosol combustion and explosion experiments, and liquid flammability risk assessments. Additionally, this paper reviews important but sparsely studied areas such as aerosol deflagration to detonation transition (DDT) and proposes a systematic strategy to investigate the complicated mechanism and consequences of aerosol combustion and explosions. [ABSTRACT FROM AUTHOR]

The novel coronavirus disease 2019 (COVID-19) epidemic that emerged in December 2019 has rapidly evolved in recent months to become a worldwide and ongoing pandemic. Shortage of medical masks remains an unresolved problem. This study aims to investigate the filtration efficiency (FE) of home-made masks that could be used as alternatives for community mitigation of COVID-19. Experimental observational analytic study. The FE of home-made masks and medical masks (as the control) were tested under laminar flow within a scaled air duct system using nebulised NaCl aerosols sized 6–220 nm. The size-resolved NaCl aerosol count was measured using a scanning mobility particle-sizer spectrometer. Home-made masks with an external plastic face shield also underwent a splash test. In addition, the fibre structures of medical masks were studied under an electron microscope after treatment with either 75% alcohol or soap and water at 60 °C. The FE of the home-made masks at 6–200 nm were non-inferior to that of medical masks (84.54% vs 86.94%, P = 0.102). Both types of masks achieved an FE of 90% at 6–89 nm. A significantly higher FE was achieved when one piece of tissue paper was added adjacent to the inner surface of the medical mask than medical mask alone (6–200 nm: 91.64% vs 86.94%, P < 0.0001; 6–89 nm: 94.27% vs 90.54%, P < 0.0001; 90–200 nm: 82.69% vs 73.81%, P < 0.0001). The plastic face shield prevented the home-made mask from fluid splash. The fibre structures of the external surface of medical masks were damaged after treatment with either 75% alcohol or soap and water at 60 °C. The home-made masks in this study, which were made of one piece of tissue paper and two pieces of kitchen towels, layered from face to external, had an FE at 6–200 nm non-inferior to that of medical mask materials, which had a certified FE of ≥95% at 3 μm. In the current COVID-19 pandemic with the shortage of medical masks, these home-made masks combined with an external plastic shield could be used as an alternative to medical masks for community mitigation. In addition, one piece of tissue paper could be placed adjacent to the inner surface of a medical mask to prolong effective lifespan of the medical mask. These demand reduction strategies could be used to reserve medical masks for use in healthcare and certain high-risk community settings, such as symptomatic persons, caregivers and attendees to healthcare institutions. • Our home-made masks have filtration efficiency comparable to medical masks. • They may be used as alternatives in low-risk community settings. • Plastic face shields may be used in situations when social distancing and/or face masks are not feasible. • Decontamination of medical masks with 75% alcohol or soap and water damages the fibres and is not recommended. • Community mitigation measures are an important part of the global efforts in combating COVID-19. [ABSTRACT FROM AUTHOR]

• Development of a new cloud model for Venus. • Modal Aerosol Dynamics applied to microphysical processes on Venus. • All processes behave as expected in the tested cases. For decades, clouds have remained a central open question in understanding the climate system of Venus. We have developed a new microphysical model for the clouds of Venus that we describe in this paper. The model is a modal aerosol dynamical model that treats the formation and evolution of sulfuric acid solution droplets with a moderate computational cost. To this end, the microphysical equations are derived to describe the evolution of the size distribution of the particles using the moments of the distribution. We describe the derivation of the equations and their implementation in the model. We tested each microphysical process of the model separately in conditions of the Venus' atmosphere and show that the model behaves in a physically sound manner in the tested cases. The model will be coupled in the future with a Venus Global Climate Model and used for elucidating the remaining mysteries. [ABSTRACT FROM AUTHOR]

• The complex dynamics physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging mainly based on the results of photochemical smog chamber simulation studies were reviewed. • The properties of the precursor VOCs, the oxidates (such as OH radicals), and the atmospheric environment (such as NO X , SO 2 , NH 3 , light intensity, temperature, humidity and seed aerosols) work together to influence the products and yield of SOA. ► Nucleation and vapor pressure of the products were found to be the most fundamental reasons for interpreting dynamics of SOA formation and aging process. • The prospects for the study direction of the SOA formation and aging are predicted. The formation and aging mechanism of secondary organic aerosol (SOA) and its influencing factors have attracted increasing attention in recent years because of their effects on climate change, atmospheric quality and human health. However, there are still large errors between air quality model simulation results and field observations. The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences. In this paper, we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging. And all these results were mainly based the studies of photochemical smog chamber simulation. Although the properties of precursor volatile organic compounds (VOCs), oxidants (such as OH radicals), and atmospheric environmental factors (such as NO x , SO 2 , NH 3 , light intensity, temperature, humidity and seed aerosols) jointly influence the products and yield of SOA, the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process. The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research. [Display omitted] [ABSTRACT FROM AUTHOR]

The quality of printed electronic sensors by aerosol jet printing (AJP) process is hard to guarantee due to an insufficient reproducibility of the AJP process. This paper proposes a novel quality inspection method to identify defects on the printed sensor by AJP process using infrared imaging and machine learning. Potentially defective regions with high temperature distributions on printed lines are estimated from the infrared imaging when the current is applied. Demanded regions for the repair are identified by a machine learning algorithm. Finally, the applicability of the proposed method has been demonstrated by repair experiments. [ABSTRACT FROM AUTHOR]

This paper describes a theoretical model which computes the collection efficiency of aerosol particles by droplets, due to the combined action of dynamic (inertia, weight and drag) and electrophoresis forces acting on an aerosol particle of radius 0.004 ≤ a ≤ 1.3 μm around a droplet of radius 15 ≤ A ≤ 100 μm. The electrostatic forces are defined following the concept of image charges. In the given particle range, the Brownian motion must be considered and was consequently added to the model. A novel approach is developed, based on the Langevin's theory and solved using an Itô process. Results of electroscavenging related to natural atmospheric ionisation, as well as for strongly charged aerosol particles released after a nuclear accident, are presented with pressure and temperature representative of the mid-troposphere (-17°C, 540 hPa). The droplet charges considered in the paper are representative of weakly and strongly electrified clouds. The values of collection efficiency computed are convenient for incorporation into cloud models and to study scavenging of aerosol particles by clouds whether for climate, pollution or nuclear safety issues. • Huge impact of the electrostatic forces on the aerosol particle collection by clouds. • Enhancement of the collection efficiency sometimes up to four orders of magnitude. • Collection efficiency increasing even with repulsive Coulomb inverse square force. • Rigorous Lagrangian model implemented for the collection efficiency computation. • Collection efficiencies available for few droplet/aerosol particle charges and radii. [ABSTRACT FROM AUTHOR]

Sea spray aerosols (SSA) are important contributors to the global aerosol load, and they have a significant impact on the global climate system and chemical processes. To better assess the environmental impact of SSA emissions, it is important to quantitatively characterize the parametric dependence of SSA production fluxes on other environmental variables, and assess their role in global climate models (GCMs) and chemical transport models (CTMs). There are currently significant differences in the simulation of global SSA production fluxes in various models, and these differences are mainly attributed to the differences in the sea spray source functions (SSSFs). Research in the literature over the last decade has greatly broadened the knowledge of SSSFs and improved our understanding of SSA production fluxes and how they are applied in models. This paper clarifies the derivation process of different SSSFs, and provides a critical review of the application progress of different SSSFs in different models, which plays an important role in improving the accuracy of model simulations to evaluate the impact of SSA. More specifically, we review the studies related to the parameterization of sea spray aerosol production fluxes in the last decade, mainly focusing on the influencing factors of SSA production, the research progress of SSSFs, and the application of SSSFs in the models. The main environmental factors that alter the production flux in SSA include wind speed, sea surface temperature, wave state, salinity, surface active organic matter, etc. To better parameterize the SSA production flux, different expressions of SSSFs have been proposed. This paper mainly summarizes from different variables such as particle size distribution dependence, whitecap coverage, sea surface temperature dependence and wave state dependence. Moreover, many studies have incorporated different SSSFs in different GCMs and CTMs to evaluate the reasonableness of SSSFs and the climate impact of SSA emissions. Finally, we summarize the current results and inadequacy of SSA production flux parameterization, and put forward the prospect of future research direction. [Display omitted] • Sea spray aerosols (SSA) are important contributors to the global aerosol load. • SSA emissions are usually parameterized by sea spray source functions (SSSFs). • The development of SSSFs is comprehensively reviewed. • SSSFs play a key role in evaluating the climate impact of SSA in models. [ABSTRACT FROM AUTHOR]

This paper evaluates the relative bias of submicron aerosol coagulation and gravity deposition experiments and model prediction results under water vapor conditions, and discusses the model prediction bias results at high steam fraction. When submicron aerosols are at room temperature and lower vapor molar ratios, the model predictions and experimental results are in good agreement. When the molar fraction of steam is high, the prediction results of the model are poor. Through analyzing thermal data and conducting gas superheating experiments, it was found that under saturated steam conditions in the experimental vessel, the number of suspended small droplets also increases with the increase of steam molar fraction. The presence of these droplets alters the coagulation and sedimentation results of submicron aerosols. Based on experimental data, this paper adds correction coefficients of coalescence and sedimentation to the original model, making it suitable for predicting submicron aerosol coagulation and sedimentation under high steam molar fraction. • Independent acquisition of aerosol experimental data at high vapor fractions. • The aerosol convergence model was established by using discretization method. • The experiment shows that there are small droplets in the saturated state. • The droplets have influence on the agglomeration and settlement of aerosol. • Correction are given for the model prediction results under high vapor fraction. [ABSTRACT FROM AUTHOR]

The frequent occurrence of highly infectious diseases in recent years has posed a serious threat to human life and public health safety and has received close attention from governments and all sectors of society in all regions of the world. The spread of pathogenic microorganisms by means of aerosols is one of the important ways to cause large-scale epidemics of mass infectious diseases. To address this issue, this paper first analyses the structural characteristics of pathogenic biological aerosols and introduces their movement coupling behavior. Secondly, based on the three main strategies currently implemented for infectious disease management engineering control, the various bioaerosol control techniques included are discussed in terms of 4 aspects: personal protective equipment, concentration dilution, filtration and clearance, and extermination and inactivation. Finally, the building and environment to which each technique is applicable is presented with respect to its characteristics. The aim of this work is to summarize the existing suppression strategies and techniques and to assist researchers in complementing and combining them. At the same time, it is hoped that the buildings and environments to which each of the technologies summarized in this paper applies will lead to further, more in-depth findings, which are not only essential for improving the current epidemic control chain but will also be useful in addressing possible future challenges. [ABSTRACT FROM AUTHOR]

A novel methodology was presented for determining the representative effective density of aerosols of a given size distribution, using a lab-made two-stage low-pressure impactor and an aerosol electrometer. Electrical currents upstream (I measured, up) and downstream (I measured, down) of the 2nd stage of the impactor were measured using a corona charger and the aerosol electrometer. In addition, the electrical currents upstream (I calculated, up) and downstream (I calculated, down) of the 2nd stage of the impactor were calculated using the aerosol charging theory. Then, the difference between the ratio of I measured, down to I measured, up and the ratio of I calculated, down to I calculated, up was iterated with varying the presumed effective density until the difference was smaller than 0.001. The methodology was validated using poly-disperse sodium chloride (NaCl) particles. The effective densities of ambient aerosols were then obtained from indoor and outdoor environments and compared with those calculated from a relation between mobility (scanning mobility particle sizer (SMPS) measurement) and aerodynamic (electrical low-pressure impactor (ELPI) measurement) diameters. Compared to the effective densities obtained with SMPS and ELPI measurements, the effective densities obtained using the methodology introduced in this paper differed within 10 % deviation, depending on measurement location. After an averaged effective density for given size distribution is obtained at a measurement location, the number-based size distribution can be easily converted to mass-based size distribution using the representative effective density. [Display omitted] • A novel method for calculating the effective density ( ρ eff) was presented. • A lab-made low-pressure impactor (LPI) and an aerosol electrometer (AE) were used. • Using LPI and AE is convenient to carry out for the field observation. • The number-based size distribution is converted to mass-based one with the density. • The density was within 10 % deviation from that obtained with reference instruments. [ABSTRACT FROM AUTHOR]

The paper investigates the physical phenomena that govern raindrop size distribution and cloud characteristics across the diverse climatic regions of the Indian subcontinent. The study focuses on four locations, Kolkata, Bhopal, Desalpar, and Kavaratti Island, during the monsoon period from 2014 to 2016. It employs various techniques, encompassing ground-based measurements from disdrometers, space-borne observations from MODIS, along with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, MEERA-2, and ERA-5 reanalysis outputs. The study found that there is a predominance of larger raindrops in Kolkata and Kavaratti Island during the monsoon season. This is due to the high atmospheric instability in these regions, which is expressed through convective available potential energy (CAPE). Locations with noticeable diurnal CAPE variations also exert influence over rainfall rates and the occurrence of raindrop sizes at different times throughout the day. Airflow patterns combined with anthropogenic activities affect aerosol levels in India. Bhopal and Desalpar have high dust levels during monsoon due to airflow from desert regions. In urban centers with significant anthropogenic activity, such as Kolkata and Bhopal, sulfate aerosols dominate, while Desalpar and Kavaratti Islands are characterized by a greater prevalence of sea salt aerosols. The dominance of different aerosol types impacted the cloud features, and, as a result, the occurrence of mean raindrop sizes at the four locations. The investigation also found that regions characterized by the predominance of larger raindrops during the monsoon season exhibit a lower cloud-effective radius normalized by the liquid water path. The variability of the raindrop size distribution impacts the empirical relationships between radar reflectivity (Z) and rain rate (R) , as well as between mass-weighted mean drop diameter (D m) and R , over the four locations. The study emphasizes the importance of considering varying Z-R relationships for accurate estimation of rain rates from radar reflectivity measurements in different climatic regions. • Varied rain microstructure observed over the different geographical locations of the Indian subcontinent. • Drop size occurrence probability is controlled by the prevailing CAPE. • CER/LWP ratio is inversely related to mean drop size. • The aerosol types influence the cloud features and as a result the prevailing DSD in a region. • The aerosol environment is controlled by the airflow pattern, geographical location, and anthropogenic activities. [ABSTRACT FROM AUTHOR]

• A generalized expression for the angular spacing of EIPI is derived. • Theoretical derivation is validated through both simulation and experimentation. • EIPI serves as an innovative application in nasal spray. • The droplet size, location, and refractive index are measured. Nasal-drug-delivery is an effective way to improve therapeutic effect. Droplet diameter and its distribution directly impact the deposition position and bioavailability of the drug in nasal passage. In this paper, the spatial distribution of the droplet size, location and refractive index of spray are explored with extended interferometric particle imaging technique. A generalized expression of the spatial spacing of interference fringes is derived theoretically. The fringe spacing for two counter-propagating beams is the same as that for a single beam along one of the two-beam directions at the sideward scattering region, which is verified by simulation and experiment. The polystyrene microsphere and the nasal spray of physiological saline and oxytocin are tested experimentally. The relative error of microsphere size is less than 0.3 %, the refractive index accuracy of spray can reach 10−4. The method presented herein is promising for many relevant applications, such as fuel spray and nasal spray. [ABSTRACT FROM AUTHOR]

This paper evaluates a three-dimensional scene construction algorithm that assigns CALIPSO-observed profiles to receiving pixels in MODIS imagery through spectral radiance matching (SRM), so that a limited number of vertically resolved aerosol observations can be expanded into a regionally continuous three-dimensional aerosol structure. The SRM algorithm was tested using moderate resolution imaging spectro-radiometer (MODIS) and cloud-aerosol lidar and infrared pathfinder satellite observation (CALIPSO) data for the period of April 10–25, 2015. First, the spectral radiance channel and the surface reflectance channel were selected for combination tests to select the best channel combination 01-04-07-26 for the application of SRM algorithm in the field of aerosol three-dimensional reconstruction. The average aerosol matching rate for this channel combination can reach 90.57%, 81.64%, 78.6%, 74.12%, and 65.96% at extended distances of 5, 20, 30, 50, and 100 km, respectively. In addition, the combination of the average correct match rate and the reconstructed aerosol structure revealed that the most suitable extension distance is up to 100 km. Then, for the reconstruction profile validation, lidar sites under four weather conditions (clean sky, aerosol loading, thin clouds, and thick clouds) were selected for validation. The comparison results reveal that the average relative errors are about 30%, 60%, 30%–60%, and 70% for these four conditions, respectively. Overall, the average relative error of the reconstructed profiles within 100 km of the orbital track of CALIPSO (except under thick cloud conditions) is less than 60%, which is within a reasonable error envelop. There are also some limitations that can be improved later by adding more constraints: 1) it is difficult to reconstruct some short-time, small-scale aerosol or cloud features; 2) it is difficult to reconstruct some hierarchical structures under thick clouds due to signal attenuation caused by thick clouds; 3) there is an underestimation of the attenuated backscatter coefficient under clouds. Finally, for aerosol optical depth (AOD), the SRM algorithm largely underestimates AOD. The reconstructed AOD is in good agreement with aerosol robotic network (AERONET), with R 2 = 0.8231 after removal of outliers. [Display omitted] • The average relative error of the 3D reconstructed profiles is between 30% and 70%. • Adding layer information can effectively enhance the reconstruction. • The reconstructed AOD is in good agreement with AeroNet observations, R 2 = 0.8231. [ABSTRACT FROM AUTHOR]

The electrostatic precipitator (ESP) is widely used in the purification of oil mist particles in the industrial workshops. Different from the solid particles, the deposition of oil mist particles in the ESP can reach a steady state and form a saturated oil film on the electrode plate. Based on the deposition experiment data, this paper has established the oil film flow model in ESP coupled with the corona discharge, the gas flow and the oil mist particle deposition model. The characteristics of oil mist particles deposition and the oil film flow were studied. The results show that the oil film is thin in the electrode plate where the current density is high. The oil film is thick at the inlet of ESP and the corresponding collection plate in the middle of the adjacent electrode wires. The peak value appears at the corresponding plate in the middle of the first two electrode wires, which is more than 50 µm. The average oil film thickness is about 9 µm in the current study. As the inlet velocity increases or the applied voltage decreases, the oil film distribution becomes more uniform, and the oil holding capacity of the electrode plate increases. [ABSTRACT FROM AUTHOR]

The primary purpose of this paper is to reveal the mechanism of suppressing hydrogen cloud explosion by micron-size water mist. On the basis of experimentally obtaining the characteristics of flame behavior and explosion pressure by changing equivalence ratio and water mist density, the physical and chemical mechanism of suppressing hydrogen cloud explosion is analyzed. The results indicated that with the increase of micron-size water mist density, the explosion-related parameters (including mean flame front speed, peak explosion pressure, peak rate of pressure rise and positive pressure impulse) of ER = 0.8 and ER = 1.0 decrease monotonously, the explosion-related parameters of ER = 2.0 increases firstly and then decreases which peak value is appeared at 26.73 g/m3. A considerable part of micron-size water mist is difficult to be completely evaporated in the reaction region, the temperature of combustion products region will be reduced due to subsequent continuous evaporation. In addition, the gasified micron-size water mist mainly interacts with H radicals through the elementary reactions of R3, R38 and R84. Due to incompletely evaporated micron-size water mist, the mist-induced turbulence is generated, which is the reason of enhancing hydrogen cloud explosion at lower micron-size water mist density of ER = 2.0. • Fine flame structure under micron-size water mist is captured. • Explosion pressure characteristics are obtained. • Physical and chemical mechanism of micron-size water mist is revealed. [ABSTRACT FROM AUTHOR]

Abstract High quality observational data with a firm uncertainty assessment are essential for the proper validation of biogeochemical models for trace metals such as iron. Typically, concentrations of these metals are very low in oceanic waters (nM and sub nM) and ICP-MS is therefore a favoured technique for quantitative analysis. Uncertainties in the measurement step are generally well constrained, even at sub-nM concentrations. However, the measurement step is only part of the overall procedure. For the determination of trace metal solubilities from aerosols in the surface ocean, aerosol collection on a filter paper followed by a leaching procedure is likely to make a significant contribution to the overall uncertainty. This paper quantifies the uncertainties for key trace metals (cobalt, iron, lead and vanadium), together with aluminium as a reference element, for a controlled, flow through laboratory leaching procedure using filters collected from three different sampling sites (Tudor Hill (Bermuda), Heraklion (Crete) and Tel-Shikmona (Israel)) and water, glucuronic acid and desferrioxamine B as leachants. Relative expanded uncertainties were in the range of 12–29% for cobalt, 12–62% for iron, 13–45% for lead and 5–11% for vanadium. Fractional solubilities for iron ranged from 0.2 ± 0.1% to 16.9 ± 3.5%. Graphical abstract fx1 Highlights • Protocol for the leaching of aerosol filters for the determination of metals. • Aerosol samples from three different locations (Tudor Hill (Bermuda), Heraklion (Crete) and Tel-Shikmona (Israel). • Three contrasting leachants used (water, desferrioxamine B and glucuronic acid). • The relative expanded uncertainty for the total amount of each metal leached from a filter paper was 7% or better. • Sufficient replication essential to achieve acceptable relative expanded uncertainty. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper is to determine an accurate formulation for the sea-spray source function characteristic for the North-Western Mediterranean. To this end, the MACMod aerosol transport model was implemented in the study area using different sea-state dependent flux formulations. The simulations were compared to a large data set of aerosol size distributions acquired over the last ten years in the study area, yielding the evolution of the sea-spray concentrations with increasing fetch and hence, with the development of the wave field. This allowed for an improvement of the Demoisson et al. (2013) sea-spray source function (S3F) for the Mediterranean. The new formulation extends its validity to shorter fetch and larger radii and turned out to be most suitable for predicting the atmospheric concentrations of sea-spray aerosols in this region. Highlights • This paper deals with the study of the sea-spray contribution to the atmospheric aerosol in the North-Western Mediterranean. • The objective is the determination of an accurate sea-spray-source function in the 0.5–20 μm size range. [ABSTRACT FROM AUTHOR]

Being able to model sodium pool fires, containment pressurization, and aerosol transport is an essential part of sodium fast reactor safety studies and source term evaluation. This paper describes recent developments to incorporate these capabilities into ASTEC-Na, a sodium-specific severe accident simulation tool currently under development by IRSN. In addition, this paper presents a comprehensive set of historical small, medium, and large-scale sodium fire experiments with which to compare experimental results. The gas temperature, gas pressure, and aerosol concentration predictions produced by the code are compared against this set of 1980’s-era sodium pool fire experiments. The code and experiments tend to agree fairly well for temperatures and pressures. There are some important discrepancies for the aerosol concentration, but these tend to be more during the cool down phase of an experiment after the fire had been extinguished. That being said, important areas for improvement have been identified that can be implemented in the ASTEC-Na in the future, e.g., new models the aerosol generation rates, are discussed. [ABSTRACT FROM AUTHOR]

Two-dimensional nano metal oxides (2D-NMOs) have attracted great concerns due to high exposure of active sites and short ion transport distance. However, 2D-NMOs with the layered structure render to restack into bulk ones, resulting in the active-sites coverage and ion-transport blockage. Here, crumpled 2D NMOs with paper-ball-like shape was proposed to avoid the restacking. Our new strategy can convert diversity of metal oxide into paper-ball-like structure with controllable composition by overcoming the fragile nature of metal oxide and limitation of growth pattern. Resultantly, as-prepared 2D NMOs demonstrated superior catalytic activity and durability in both oxygen evolution reaction (OER) and organic dye degradation reaction, owing to their high exposure of active sites and low ionic diffusion resistance. [Display omitted] • More than 18 crumpled ball-like metal oxide-based catalysts enabled by aerosol synthesis, which was to assemble 2D NMOs into 3D crumpled morphology. • Ultrafine nanocrystals interconnected to form 2D nanosheets in NMOs, endowing more active sites and highly exposed surface. • The crumpled morphology demonstrated superior catalytic activity and durability in both OER and degradation. • Crumpled ball-like metal oxide-based catalysts were assembled by aerosol synthesis, which has more active sites, highly exposed surface and efficient channels. [ABSTRACT FROM AUTHOR]

• The relationship between the explosion overpressure and flame evolution of ethanol aerosols has been elucidated. • The intensity of the ethanol aerosol explosion and the speed of flame propagation increase with the initial pressure. • When P0 ≤ 70 kPa, an orange-yellow transitional phase occurs during the development of the flame. Ethanol is one of the most common renewable fuels and chemical raw materials, and there is a risk of aerosol explosion disasters at all stages of its production, transport, storage, and use. This paper investigates the explosion overpressure and flame propagation characteristics of ethanol aerosols at different equivalence ratio under sub-atmospheric pressure conditions in a square closed vessel. The results show that the maximum explosion pressure (P max), the maximum rate of pressure rise ((dP/dt) max), and the explosion index (K a) of ethanol aerosol explosions increase with the equivalence ratio, peaking at an equivalence ratio of 1.45, reaching values of 0.92 MPa, 20.25 MPa/s, and 4.73 MPa·m/s, respectively. The variation in Pmax with equivalence ratio can be fitted by a cubic polynomial function. P max , (dP/dt) max , and K a all increase linearly with the initial pressure. The evolution speed and luminosity of the ethanol aerosol explosion flames are stronger in rich fuel conditions than in lean fuel conditions, and the explosion combustion time is also shorter in rich fuel conditions. Moreover, when the initial pressure is less than or equal to 70 kPa, the blue flame of the ethanol aerosol explosion is initially dim in color, displaying an orange-yellow transitional phase before turning into a dazzling white. The flame propagation speed undergoes four stages as displacement increases: rapid increase, high-speed maintenance, rapid decline, and oscillatory weakening. The findings provide experimental data and theoretical support for preventing and mitigating explosion disasters of alcohol-based fuel aerosols under sub-atmospheric pressure conditions. [ABSTRACT FROM AUTHOR]

The radioactive aerosols deposited wash-down by condensate on walls in containment is one of the pathways for radioactive migration. Condensate film coverage is critical to the transport properties of aerosol particles during wash-down. In this paper, an experimental study was carried out to visualize the processes of condensation and aerosol wash-down on an aerosol-containing wall. The evolutionary pattern of condensate was observed in the experiment. Variations in condensate coverage on walls with different inclination angles of 0°, 0.4°, 2°, 30°, and 90° were noted. The effect of coverage on aerosol removal efficiency was also analyzed based on the results. Experimental results show that wall coverage on horizontal (0°) or quasi-horizontal walls (0.4°) is close to 100 %. For inclined or vertical walls, under the influence of thermal capillary forces, rivulets are the main forms of condensate coverage, with the maximum area that can be covered by rivulets being about 2/3 of the wall area. The experimental results show that the removal efficiency of aerosol during washing will be higher than the coverage rate of condensate. In the experiments, both condensation rate and aerosol loading tended to promote the spreading of condensate. [ABSTRACT FROM AUTHOR]

The role of atmospheric aerosols has remained hugely uncertain due to lack of long-term systematic observations. This is particularly the case in the global emission hotspot the Indo-Gangetic Plain. In this paper, we apply a machine learning (ML) approach to fill gaps in aerosol observations by combining meteorological reanalysis, and satellite-observations. Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA), and Asymmetry Parameter (AP) are critical parameters for understanding the atmospheric aerosol properties, radiative forcing and climate patterns. We considered AOD, SSA, and AP over an urban site, Kanpur, in the Indo-Gangetic Plain, which is a global hot-spot of high aerosol loading. We used ML technique to fill the observational gaps in AOD, SSA, and AP at 440 nm. Accurate ground-based daily observations of AOD, SSA, and AP from AERONET (Aerosol Robotic Network) over a period of ∼2 decades (2001–2022) are used in the analysis, which have ∼ 37%, ∼62%, and ∼58% data gap, respectively. To reduce observational gaps, an ML model was trained with reanalysis (meteorological parameters) and satellite (angstrom exponent and absorbing aerosol index) datasets by optimally tuning the hyperparameters. The model tested on unseen data showed that it could simulate the AOD (coefficient of determination, R2 = 0.51 and refined index of agreement, RIA = 0.66), SSA (R2 = 0.60 and RIA = 0.70), and AP (R2 = 0.64 and RIA = 0.71), successfully with moderate accuracies: root mean square error of 0.25, 0.018, and 0.018, respectively. This magnitude of error in AOD is comparable to the errors, 0.26 and 0.25, in satellite (MODIS-Moderate Resolution Imaging Spectroradiometer) derived and reanalysis (MERRA-2- Modern-Era Retrospective analysis for Research and Applications, Version 2) AODs, respectively for the study region. When MODIS AOD was included as a predictor in the ML model, it could reproduce AOD with much smaller errors of 0.14, reproducing 84% of total variability. Thus, based on available input data, we reduced observational gaps of daily AOD, SSA, and AP by ∼10% (∼2 years), ∼23% (∼5 years), and ∼21% (∼4 years), respectively, at the study region. Aerosol Radiative Forcing (ARF) at the top-of-atmosphere was estimated using AOD, SSA, and AP both with and without gap-filling. We found that data gaps can significantly impact the estimations of aerosol climate forcing. A considerable change in ARF, ∼ ± 3 Wm−2 indicating that the observational gaps can mislead our understanding of aerosols' impact on climate. This points toward the need for more comprehensive measurements with minimal observational gaps. Our study highlights the possibility of compensating observational gaps by an optimised ML model and that such innovative approach can potentially lead to better understanding of impact of aerosols on climate. Further, the present study could be of immense interest for the community as our validated approach can be applied for other pollutants and for other data-scarce regions in the South and Southeast Asia. • Machine-learning approach to fill up the gaps in aerosol observations over a global hotspot region. • Validated ML model used to fill ∼ 23% data exploiting meteorological and satellite datasets. • Uncertainty in presented ML model smaller than those in satellite/chemical-transport model. • Data gaps affect estimation of aerosols climate forcing by ∼ 3 Wm−2. • The optimised ML model can improve our understanding on aerosol-climate interactions. [ABSTRACT FROM AUTHOR]

• Acoustic pulsations enhance mass transferin the aerosol phase. • Micrometer-size dropletsare translocatedlaterally from the aerosol stream. • Aerosol deposition in the nasal cast is enhanced by pulsations. • Process intensification concepts can be successfullyapplied to medicine. Process intensification (PI) concepts have potential applications beyond the classic industrial problems solved by chemical engineering. This paper discusses the flow and mass transfer intensification using acoustic waves to enhance drug delivery to the nasal cavity. The efficiency of drug delivery to the nose still needs improvement, and the mechanisms related to using acoustic waves to increase it have yet to be studied. The influence of pressure pulsations induced by an acoustic wave (∼100 Hz) on the concentration, droplet size, and flow structure of the mists delivered from medical nebulizers was studied. The direct visualization showed that pulsations intensify aerosol deposition inside narrow channels due to particle displacement perpendicularly to the main flow direction. This motion also allows for particle penetration via narrow openings. UV-assisted observation of the intensified aerosol deposition inside the anatomical cast of the nasal cavity confirmed the importance of acoustic pulsations for intranasal drug delivery, also helping aerosol penetrate hard-to-reach areas (including the paranasal sinuses). A new idea regarding appropriate time control of acoustic pulsations has been proposed to improve the aerosol drug mass transfer in the nose. The study shows that PI has great potential to expand into new and interdisciplinary areas. [Display omitted] [ABSTRACT FROM AUTHOR]

This study presents a microscale simulation method that allows one to study the impact of particle loading on the aerosol capture efficiency of an electrostatically charged filter. This was done by considering a bipolarly charged fiber loaded with different amounts of neutral and charged particles with a diameter of 300 nm. The simulations predicted the deposition pattern of the aerosol particles as well as their impact on the electrostatic field of the bipolar fiber. The particle-loaded fiber was then challenged with aerosol particles in the range of 50 nm to 1 μm and with different charge polarities to study how the electrostatic field of the deposited particles interacts with that of the fiber to attract or repel the incoming airborne particles. More specifically, our simulations revealed that particle deposition can enhance the capture efficiency of a bipolar fiber when it is challenged with small particles (smaller than about 400 nm) regardless of the charge polarity of the airborne or deposited particles. The numerical simulations reported in this paper were conducted using the ANSYS CFD code enhanced with in-house subroutines to superimpose the electrostatic field of the deposited particles to that of the bipolar fiber and to include Brownian, polarization, and Coulomb forces in particle trajectory calculations. [Display omitted] • Simulated the electrostatic field around a particle-loaded corona-charged fiber. • Demonstrated the impact of particles' electrostatic field on fiber's capture efficiency. • Discussed the effects of fiber polarity on particle loading. • Demonstrated agreement between simulation results and experimental observations. [ABSTRACT FROM AUTHOR]

This paper investigates performance of seven photovoltaic (PV) array topologies experimentally under cumulative impact of partial shading and deposition of aerosols at different irradiance levels and aerosol types at their different concentration levels. Different array topologies respond differently with regard to their mismatch power loss and fill factor under partial shaded condition. However, a comprehensive analysis of their behavior under the influence of other environmental phenomena is neglected so far by the researchers. The topologies studied in the present work, include four conventional topologies viz . series-parallel (SP), honey comb (HC), bridge link (BL) and total cross-tied (TCT) along with three novel hybrid topologies proposed in this paper (CT-SP, CT-BL and CT-HC). The complex and large amount of data generated from the experimental study have been analyzed using combined Shannon's entropy and data envelopment analysis to quantify the relative performances of different PV array topologies under different environmental conditions. The proposed methodology of comprehensive analysis will help the policy makers and researchers to enhance the performance ratio of PV projects by leveraging on the environmental factors and thereby increase techno-commercial viability of the PV projects. [ABSTRACT FROM AUTHOR]

In this paper, a climatological study focused on the analysis of atmospheric aerosols properties over Burjassot and Aras de los Olmos AERONET sites, located at Eastern Spain, is performed. Computed mean values for Aerosol Optical Depth (AOD 440), Ångström exponent (α 440 − 870) and columnar water vapor (w) in Burjassot (Aras de los Olmos) are 0.19 ± 0.08 (0.10 ± 0.02), 1.21 ± 0.16 (1.18 ± 0.25) and 1.87 ± 0.68 cm (0.94 ± 0.10 cm), respectively. From the monthly statistics of w and AOD , it is concluded that summer months are characterised by higher humidity and turbidity, being the latter favoured by particle stagnation, recirculation, secondary aerosol formation, hygroscopic processes and North African dust intrusions. Regarding the volume size distribution, well developed fine and coarse modes are found in summer. On the other hand, the spectral dependence of the asymmetry parameter (g) describes a decrease in λ up to 870 nm , and then a slight increase due to the influence of dust particles. The computed mean values for the asymmetry parameter (g 440) are 0.700 ± 0.013 (0.709 ± 0.016) for Burjassot (Aras de los Olmos). With respect to the Single Scattering Albedo (SSA) and the complex refractive index, an additional analysis using Level 1.5 data is performed, as relatively few data points pass the filters imposed by the Level 2.0 conditions. In the case of SSA, which is found to be larger in spring and summer months, the obtained mean annual values at 440 nm are 0.94 ± 0.03 (0.95 ± 0.03) for Burjassot (Aras de los Olmos). Finally, regarding the complex refractive index, the mean values of the real part (m 440) are 1.50 ± 0.03 (1.49 ± 0.03), and for the imaginary part (∣ k 440 ∣) are 0.007 ± 0.004 (0.004 ± 0.003) in Burjassot (Aras de los Olmos). The present study is complemented with three analyses based on the distinction between the different aerosol types. To begin with, these are classified according to their nature, being the most abundant continental clean aerosols. Next, Gobbi diagrams are plotted for both sites, depicting a clustered region of coarse aerosols, as well as particle growth traces. Finally, the different air masses affecting the measurement sites are studied, reaching to the conclusion that these originated in the European and the African continents are the most turbid ones. To conclude this study, a seasonal Mann-Kendall test is applied to AOD, α , w and SSA measurements in order to study possible trends. Hence, a statistically significant (> 80 %) decreasing trend in AOD is observed for most months; whereas α , w and SSA do not show statistically significant long-term trends, only for a few months of the year. • 20 (6) years AERONET data studied for Burjassot (Aras de los Olmos) in Eastern Spain. • Continental clean aerosols are dominant over Burjassot and Aras de los Olmos. • AOD, α and ω higher at Burjassot than Aras de los Olmos due to its urban character. • European and African air masses are responsible for high turbidity measurements. • AOD decreases with 80% confidence level; but α and SSA trends are not statistically significant. [ABSTRACT FROM AUTHOR]

Aerosol types have crucial and distinguished impacts on climate effects and cause the difference of air pollution. However, direct retrieval of aerosol type by satellite remote sensing is difficult, and the satellite products of aerosol type are seriously lacking. At present, the identification of aerosol type is mainly based on ground-based observation data, but the coverage area of ground-based stations is limited, and large-scale spatial continuous monitoring cannot be carried out. The existing aerosol type identification methods based on satellite data need to combine multiple satellites data (e.g. Moderate-resolution Imaging Spectroradiometer (MODIS), Ozone Monitoring Instrument (OMI), etc.) which leads to a low temporal resolution. The research about aerosol type identification only based on geostationary satellite data is lacking. Therefore, aerosol type identification based on the multi-parameter threshold method and the neural network method are proposed and compared in this paper. The neural network jointly using spectral and temporal information was trained and tested by the measurements from 26 sites of Aerosol Robotic Network (AERONET) and Sun-Sky Radiometer Observation Network (SONET). For the overall validation, the aerosol type identification based on the neural network is better than that based on the multi-parameter threshold method, and the accuracy reaches 71.44%. Atmospheric environment monitoring and quantitative remote sensing can be supported by this study. • Aerosol type, neural network, geostationary satellite [ABSTRACT FROM AUTHOR]

Elongated drug particles have the potential to be superior to spherical drug particles for delivery to the deep lung due to their increased ability to align with the airflow. However, the performance of elongated particles within dry powder inhalers (DPIs) has been largely unexplored. This paper presented a CFD-DEM study to simulate the dispersion of elongated active pharmaceutical ingredient (API) particles with equivalent sizes of 1.55–5.53 μm in a commercial DPI device Turbuhaler ®. The model, which adopted a multi-sphere approach to mimic the shape of elongated spherocylindrical particles, was validated by comparing experimental data of fluidized beds. The model was then utilized to simulate the dispersion of powders with different aspect ratios in Turbuhaler. Findings revealed that the depositions of elongated particles in the chamber and the mouthpiece were significantly higher than those of spherical particles, and the depositions increased with higher aspect ratios. The higher deposition of the elongated particles was due to much stronger inter-particle cohesion when particles were in flat contact with particles or wall surfaces. Similar to spherical particles, both emitted dose and fine particle fraction (FPF, % mass of particles below 5 μm) of elongated particles increased with flow rates due to intensified particle-wall collisions. On the other hand, the FPF of elongated particles in the device decreased more significantly with increasing cohesion than spherical particles. Results indicated that while elongated particles are preferred for drug delivery to deeper lungs, their poor dispersion in inhalers due to higher deposition needs to be considered. [Display omitted] • Dispersion of elongated particles in Turbuhaler® was studied by a CFD-DEM model. • Model was validated with fluidised bed experiments. • Elongated particles showed higher device deposition than spherical particles. • Particle-wall collisions dominated dispersion of elongated particles. • Higher flow rate and lower particle surface energy enhanced collisions. [ABSTRACT FROM AUTHOR]

Summer 2019 is remembered as one of the most intense biomass burning (BB) seasons on record for the Northern Hemisphere. During the MOSAiC expedition, a smoke-dominated layer was identified in the upper troposphere over the North Pole region. The origin of this layer remains unclear, and no evidence has been found to indicate the intrusion of such particles into the Arctic Boundary Layer. The main aim of this work was to evaluate if biomass burning events in the summer 2019 were detectable at Gruvebadet Atmospheric Laboratory, close to Ny-Å lesund (Svalbard Islands) during the second half of 2019. This paper proposes an innovative approach to discriminate biomass burning events based on optical measurements combined with chemical analysis and air mass back-trajectories. Monthly background values of optical coefficients were defined using multi-annual (2018–2021) statistics and twelve possible events were identified. Source apportionment through positive matrix factorization (PMF) identified that the biomass burning factor by PMF accounted for only 2% of the total investigated concentration. The specific biomass burning tracers such as levoglucosan and phenolic compounds were compared with optical measurements and with the PMF results. Air mass trajectory analysis revealed that the early summer fires detected at Ny-Å lesund originated mainly from North America, as also confirmed by the presence of BB factor of PMF, levoglucosan and also vanillic species (softwood combustion tracers). In contrast, the chemical composition and air masses analysis of the highest peak detected in early December suggested residential heating as plausible source, further amplified by the onset of the harsh winter season and the expansion of the polar vortex towards mid-latitudes. • 12 mild pollution events have been identified investigating optical properties. • Biomass burning's contribution accounted for 2% of the total concentration. • Most of the events were detected during the fall. • The latest events in December may have been impacted by emissions from home heating. [ABSTRACT FROM AUTHOR]

• The first study of indoor air pollution by LIBS and SPAMS technology. • The whole detection process is carried out in real time. • The monitoring of indoor carbon concentration is realized by LIBS technology. • Machine learning is applied to identify pollutants with different concentrations. With the improvement of science and technology, more and more activities can be carried out indoors. Generally speaking, people spend 70–90 % of their life indoors. Therefore, the quality of indoor air is closely related to people's health. It is very important and necessary to carry out the online in situ detection of indoor air pollution. In this paper, laser induced breakdown spectroscopy (LIBS) technology and single particles aerosol mass spectrometer (SPAMS) technology are used to detect indoor air pollution caused by electronic welding operation. In the process of electric welding operation, a large amount of smoke containing metal particles is produced, which is very harmful to human health and the environment. According to the experimental results, the main components in the smoke are Pb and Sn. Their isotope and abundance information are also obtained. Moreover, the online monitoring of indoor carbon concentration during continuous operation is conducted. In addition, the semi quantitative analysis of Pb and Sn in smoke is performed. Finally, combined with principal component analysis (PCA) and error back propagation artificial neural network (BP-ANN), different smoke are classified and identified. [ABSTRACT FROM AUTHOR]

This paper presents new findings on polycyclic aromatic hydrocarbon oxidation products–quinones that were collected in ambient air samples in the proximity of oil sands exploration. Quinones were characterized for their diurnal concentration variability, phase partitioning, and molecular size distribution. Gas-phase (GP) and particle-phase (PM) ambient air samples were collected separately in the summer; a lower quinone content was observed in the PM samples from continuous 24-h sampling than from combined 12-h sampling (day and night). The daytime/nocturnal samples demonstrated that nighttime conditions led to lower concentrations and some quinones not being detected. The highest quinone levels were associated with wind directions originating from oil sands exploration sites. The statistical correlation with primary pollutants directly emitted from oil sands industrial activities indicated that the bulk of the detected quinones did not originate directly from primary emission sources and that quinone formation paralleled a reduction in primary source NO x levels. This suggests a secondary chemical transformation of primary pollutants as the origin of the determined quinones. Measurements of 19 quinones included five that have not previously been reported in ambient air or in Standard Reference Material 1649a/1649b and seven that have not been previously measured in ambient air in the underivatized form. This is the first paper to report on quinone characterization in secondary organic aerosols originating from oil sands activities, to distinguish chrysenequinone and anthraquinone positional isomers in ambient air, and to report the requirement of daylight conditions for benzo[ a ]pyrenequinone and naphthacenequinone to be present in ambient air. [ABSTRACT FROM AUTHOR]