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Here, it is investigated how optical properties of single scatterers in interacting multi‐particle systems influence measurable structure factors. Both particles with linear gradients of their scattering length density and core–shell structures evoke characteristic deviations between the weighted sum ⟨S(Q)⟩ of partial structure factors in a multi‐component system and experimentally accessible measurable structure factors SM(Q). While ⟨S(Q)⟩ contains only the structural information of self‐organizing systems, SM(Q) is additionally influenced by the optical properties of their constituents, resulting in features such as changing amplitudes, additional peaks in the low‐wavevector region or splitting of higher‐order maxima, which are not related to structural reasons. It is shown that these effects can be systematically categorized according to the qualitative behaviour of the form factor in the Guinier region, which enables assessing the suitability of experimentally obtained structure factors to genuinely represent the microstructure of complex systems free from any particular model assumption. Hence, a careful data analysis regarding size distribution and optical properties of single scatterers is mandatory to avoid a misinterpretation of measurable structure factors. [ABSTRACT FROM AUTHOR]

Due to the potential danger of exposure to aerosol particles on the human body, maximum permissible concentrations of harmful substances are limited by current regulatory documentation. The formation of aerosol particles is possible during beyond design basis accidents at nuclear power plants. The consequences of the radioactive impact of radioactive aerosol particles formed during an accident at a nuclear power plant on the human body are significantly more severe than from the mechanical impact of such particles. An important characteristic of radioactive aerosol particles is their polydispersity (unevenness in size) since particles of different sizes during an accident at a nuclear power plant have different rates of removal from the atmosphere of the nuclear power plant's containment. Thus, when considering the movement of particles in the containment and the release of aerosol particles into the environment, it is important to correctly model the size distribution of aerosol particles. This paper presents the results of calculating the count and mass distributions of aerosol particles by size in the TOSQAN and Phebus-FP experiments. Methods are given for describing polydisperse systems (using particle size distribution or "average" sizes characterizing the entire distribution) and their influence on processes associated with the transfer of aerosol particles in a containment, and practical recommendations for working with particle size distributions are given. A comparison is made of the use of average size distribution characteristics and the lognormal distribution of aerosol particles to estimate the release during a hypothetical accident at a nuclear power plant with VVER. [ABSTRACT FROM AUTHOR]

Ventilation may lead to a deterioration in indoor air quality in urban environments located close to roads. Understanding the differences in the chemical compositions of size-resolved particulate matter (PM) in indoor air and outdoor air could aid in assessing the health impacts of air in these settings and establishing relevant regulation policies. In this study, indoor and outdoor size-resolved PM was collected from an office in Beijing in summer (between 5 and 25 July 2020) and winter (between 5 and 31 January 2021). Its chemical components, including sulfate, nitrate, ammonium, chlorine, organic matter (OM), elemental carbon (EC), crustal materials (CM), and heavy metals (HM), were analyzed. The mean levels of indoor and outdoor PM2.1 and PM9 were found to be much higher than those in the guidelines for PM2.5 and PM10 outlined by the National Ambient Air Quality Standard. Moreover, the levels of PM2.1 and PM2.1–9 mass were higher outdoors than they were indoors. The size distributions of mass concentrations were shown to be bimodal, peaking at 0.43–0.65 μm and 4.7–5.8 μm, respectively. The most abundant chemicals were OM, nitrate, and sulfate for PM2.1 and OM, CM, and nitrate for PM2.1–9. We found higher percentages of sulfate, nitrate, ammonium, EC, and HM in smaller-size fractions of PM. Additionally, positive matrix factorization showed that biomass burning, secondary inorganic aerosol, coal combustion, dust, traffic, and industrial pollution were the main sources of PM during the study period. The greatest non-carcinogenic and carcinogenic hazards were found at 0.43–0.65 μm in summer and 2.1–3.3 μm in winter. Our results indicate that size-resolved PM of ambient origin may infiltrate buildings near roads to varying degrees, resulting in negative health effects. [ABSTRACT FROM AUTHOR]

Most current research focusing on the health risk assessments of particulate polycyclic aromatic hydrocarbons (PAHs) have not analyzed the size distributions and human respiratory deposition rates. In the present study, size‐separated particulate matter (PM) was collected in the coastal area of Ningbo using an Anderson eight‐stage air sampler over a 1‐year period (2014–2015). The 16 US Environmental Protection Agency priority PAHs associated with PM were pretreated with rapid solvent extraction and analyzed by gas chromatography–mass spectrometry. The respiratory exposure assessment was determined using the multiple‐path particle dosimetry (MPPD) model. The results show that all PAHs exhibited bimodal distribution with one mode peak in accumulation mode (0.43–0.65 µm) and another mode peak in coarse mode (4.7–5.8 µm). In addition, a low coefficient of divergence of PAHs between PM2.1 and PM2.1−10 indicated a high spatial heterogeneity in source factor contribution and formation mechanism. The deposition fluxes (tracheobronchial + pulmonary) of PM were highest for children in the size range of 3.3 µm < particle diameter (Dp) < 9 µm, while for males and females the highest fluxes occurred in the size range of 1.1 µm < Dp < 2.1 µm. The depositions of coarse PM in children were significantly higher than those in adults. The benzo[a]pyrene equivalent (BaPeq) depositions of dibenz[a,h]anthracene ranged from 1.4e‐04 to 0.015 ng h−1, which were highest among the PAHs. The PAHs on particles with Dp >4.7 µm contributed approximately three times more to children than to males and females. Therefore, the toxicity of coarse PM to children needed attention. The incremental lifetime cancer risks (ILCR) for children, males, and females were estimated to be 2.92 × 10−7, 1.82 × 10−7, and 2.38 × 10−7, respectively, which were below the cancer risk guideline value (10−6). These ILCR values were much lower than the risks calculated without considering particle size distributions and respiratory depositions. The combination of the size‐segregated sampling technique and the MPPD model can effectively avoid the overestimation of human respiratory exposure. Environ Toxicol Chem 2024;43:1364–1377. © 2024 SETAC [ABSTRACT FROM AUTHOR]

The concentrations of anhydrosugars (levoglucosan, mannosan, and galactosan), polyols (inositol, xylitol, sorbitol, and mannitol), and glucose were measured in PM1 and PM10 samples collected during 1 year at a traffic site in the city of Elche (southeastern Spain). Levoglucosan, mannosan, and galactosan were mainly found in the PM1 fraction since they are mainly emitted from biomass burning (BB). Likewise, inositol, xylitol, and sorbitol were primarily distributed in the fine mode, suggesting a non-negligible contribution from anthropogenic sources (specifically BB) to the levels of these compounds. This was supported by their seasonal variations, with higher concentrations during winter, and their correlations with levoglucosan concentrations. The average contributions of biomass burning and biogenic sources to OC and PM levels were calculated using levoglucosan and mannitol, respectively, as tracers. On average, BB accounted for 12% and 16% of the OC in PM1 and PM10, while the estimated contribution of fungal spores to OC and PM10 levels was 1.2 and 0.8%, respectively. The results of the present study suggest that, at least in the study area, most sugar alcohols are not appropriate tracers of biogenic emissions. [ABSTRACT FROM AUTHOR]

In this paper, the dependence of the Young’s elastic modulus of a mesoporous material on the geometric characteristics (volume and shape) of pores has been analyzed. The geometric characteristics of pores have been determined in the framework of the fractal-geometry approach by the values of their effective diameter and fractal dimension. The presented estimates demonstrate that the effect (being characteristic of nanoscale particles), which consists a significant dependence of elastic moduli on the size and shape of a particle, can also be realized in mesoporous materials (the pore size being form 5 up to 50 nm) while the mesoporous samples themselves can be of macroscopic dimensions. Using the example of mesoporous silver, it has been shown that reducing the pore size and «complicating» the pore shape lead to a significant decrease in the Young’s elastic modulus. The results have been obtained in the framework of the cohesive energy-based model.

Particulate matter (PM) from residential combustion is an existential threat to human health. Emission factors (EFs) of multiple potential toxic components (PTCs) in size-resolved PM and gas from eight residential fuel combustion were measured, and size distribution, gas/particle partitioning and health risks of the PTCs were investigated. Average EFs from clean coal and anthracite coal were PTEs (sum of EFs of 11 Potential Toxic Elements, 6.62 mg/kg fuels) > PAHs (sum of 22 Polycyclic Aromatic Hydrocarbons, 1.12 mg/kg) > OPAHs (sum of 5 Oxygenated Polycyclic Aromatic Hydrocarbons, 0.45 mg/kg) > PAEs (sum of 6 Phthalate Esters, 0.11 mg/kg) > NPAHs (sum of 14 Nitropolycyclic Aromatic Hydrocarbons, 16.84 μg/kg) > OPEs (sum of 7 Organophosphate Esters, 7.57 μg/kg) > PCBs (sum of 6 Polychorinated Biphenyls, 0.07 μg/kg), which were 2–3 and 1–2 orders of magnitude lower than the EFs of PTCs (except PTEs) from bituminous coal and biomass. Most PAHs, OPAHs and NPAHs, which may mainly originate from chemical reactions, showed similar size distributions and averagely 85 % concentrated in PM1. PTEs, PAEs, OPEs and PCBs generated from the release from raw fuels may have a higher proportion, so their size distributions were more complex and varied with combustion temperature, volatility of compounds, binding mode of the raw fuels, and so on. In addition, clean coal and high-quality anthracite coal could reduce the health risks from the potential organic toxic components, but also reveal the stumbling block of PTEs in risk control.

Ventilation may lead to a deterioration in indoor air quality in urban environments located close to roads. Understanding the differences in the chemical compositions of size-resolved particulate matter (PM) in indoor air and outdoor air could aid in assessing the health impacts of air in these settings and establishing relevant regulation policies. In this study, indoor and outdoor size-resolved PM was collected from an office in Beijing in summer (between 5 and 25 July 2020) and winter (between 5 and 31 January 2021). Its chemical components, including sulfate, nitrate, ammonium, chlorine, organic matter (OM), elemental carbon (EC), crustal materials (CM), and heavy metals (HM), were analyzed. The mean levels of indoor and outdoor PM2.1 and PM9 were found to be much higher than those in the guidelines for PM2.5 and PM10 outlined by the National Ambient Air Quality Standard. Moreover, the levels of PM2.1 and PM2.1–9 mass were higher outdoors than they were indoors. The size distributions of mass concentrations were shown to be bimodal, peaking at 0.43–0.65 μm and 4.7–5.8 μm, respectively. The most abundant chemicals were OM, nitrate, and sulfate for PM2.1 and OM, CM, and nitrate for PM2.1–9. We found higher percentages of sulfate, nitrate, ammonium, EC, and HM in smaller-size fractions of PM. Additionally, positive matrix factorization showed that biomass burning, secondary inorganic aerosol, coal combustion, dust, traffic, and industrial pollution were the main sources of PM during the study period. The greatest non-carcinogenic and carcinogenic hazards were found at 0.43–0.65 μm in summer and 2.1–3.3 μm in winter. Our results indicate that size-resolved PM of ambient origin may infiltrate buildings near roads to varying degrees, resulting in negative health effects.

TiN, a typical nonmetallic titanium inclusion, is regarded harmful for the quality of hypereutectoid tire cord steel. At present, the effective methods of controlling the TiN inclusions in the high‐carbon tire cord steel are still uncertain. Herein, the precipitation and solid solution behavior of the TiN inclusions in SWRH92A tire cord steel are studied. The main characteristics, e.g., size distribution and morphology, of the TiN inclusions precipitated under different steel remelting conditions (e.g., Ti and N concentrations and cooling rate) are analyzed. The results indicate that the average TiN inclusion size is proportional to the Ti and N concentration product, and Ti shows larger effect on the TiN inclusion size than N. For the samples with heat treatment, the number percentage and average size of larger TiN inclusions decrease compared with reference sample. As heating temperature increases from 1150 to 1250 °C, the total TiN inclusion number decreases, and the number percentage and average size of larger TiN inclusions decrease. After heating, the sample with a higher cooling rate has a higher number percentage of finer inclusions and the average size of larger inclusions is smaller, indicating that increasing cooling rate is helpful to refining the TiN inclusions. [ABSTRACT FROM AUTHOR]

Environmental persistent free radicals (EPFRs) are receiving growing concerns owing to their potentially adverse impacts on human health. Road dust is one important source of air pollution in most cities and may pose significant health risks. Characteristics of EPFRs in urban road dusts and its formation mechanism(s) are still rarely studied. Here, we evaluated occurrence and size distributions of EPFRs in road dusts from different functional areas of an urban city, and assessed relationship between EPFRs and some transition metals. Strong electron paramagnetic resonance signals of 6.01 × 1016 − 1.3 × 1019 spins/g with the mean g value of 2.0029 ± 0.0019 were observed, indicating that EPFRs consisted of a mixture of C-centered radicals, and C-centered radicals with an adjacent oxygen atom in the urban road dust. Much more EPFRs enriched in finer dust particles. EPFRs significantly correlated with the total Fe, but not water-soluble Fe, suggesting different impacts of water-soluble and insoluble metals in the formation of EFPRs. Health risk assessment results indicated high risk potentials via the ingestion and dermal exposure to EPFRs in road dusts. Future studies are calling to look into formation mechanisms of EPFRs in urban road dusts and to quantitatively evaluate its potential risks on human health. [ABSTRACT FROM AUTHOR]

Particulate secondary organic nitrates play a key role in understanding secondary organic aerosol production, ozone formation, and the atmospheric nitrogen cycle. However, the formation of particulate secondary organic nitrates in ambient air remains poorly understood. In this study, the nighttime formation processes of particulate secondary organic nitrates were investigated based on size‐resolved aerosols measured in urban air of China with a soot particle long‐time‐of‐flight aerosol mass spectrometer. The results show a bimodal size distribution of particulate secondary organic nitrates, peaking at ∼350 nm in condensation mode (100–400 nm) and ∼750 nm in droplet mode (400–2,500 nm), respectively. The nighttime formation processes of particulate secondary organic nitrates in the two size modes were respectively governed by temperature‐dependent condensation and aqueous‐phase processing. In particular, the mass concentration of particulate secondary organic nitrates in condensation mode was positively correlated with nitrate radical production and negatively correlated with temperature, suggesting that the formation processes were associated with the gas‐particle conversion of nitrate radical oxidation products. In contrast, the enhanced particulate secondary organic nitrates in droplet mode were predominantly contributed by aqueous‐phase processing, as indicated by the strong positive correlation with aerosol liquid water content and typical fragment ions from aqueous processing products (r = 0.52–0.59, P < 0.01). Our results highlight the potential of a size‐dependent mechanism to elucidate the formation processes of particulate secondary organic nitrates. Plain Language Summary: Particulate organic nitrates are an important nitrogen‐containing compound in the ambient atmosphere and have significant effects on air quality. However, the formation processes of particulate organic nitrates are complex in ambient air, leading to difficulties in understanding of their atmospheric processes and impacts. Here, nighttime formation of particulate secondary organic nitrates in different size particles is investigated in urban air. The results show that the nighttime formation pathways of particulate secondary organic nitrates in different size particles are distinct. Furthermore, aqueous processing plays an important role in the nighttime formation of particulate secondary organic nitrates in large size particles, especially in fog‐rain days. This information provides for a better understanding of the formation of particulate secondary organic nitrates in ambient air and is useful for future design of laboratory and atmospheric chemistry model studies. Key Points: Particulate secondary organic nitrates concentrations were significantly enhanced during fog‐rain days compared to non‐fog‐rain daysSize distributions of secondary organic nitrates were characterized by bimodal structure, peaking at ∼350 and ∼750 nm, respectivelyThe nighttime formation of organic nitrates in two size modes was respectively dominated by gas‐particle partitioning and aqueous processing [ABSTRACT FROM AUTHOR]

Rainfall-triggered shallow landslides are destructive hazards and play an important role in landscape processes. A theory explaining the size distributions of such features remains elusive. Prior work connects size distributions to topography, but field-mapped inventories reveal pronounced similarities in the form, mode, and spread of distributions from diverse landscapes. We analyze nearly identical distributions occurring in the Oregon Coast Range and the English Lake District, two regions of strikingly different topography, lithology, and vegetation. Similarity in minimum sizes at these sites is partly explained by theory that accounts for the interplay of mechanical soil strength controls resisting failure. Maximum sizes, however, are not explained by current theory. We develop a generalized framework to account for the entire size distribution by unifying a mechanistic slope stability model with a flexible spatial-statistical description for the variability of hillslope strength. Using hillslope-scale numerical experiments, we find that landslides can occur not only in individual low strength areas but also across multiple smaller patches that coalesce. We show that reproducing observed size distributions requires spatial strength variations to be strongly localized, of large amplitude, and a consequence of multiple interacting factors. Such constraints can act together with the mechanical determinants of landslide initiation to produce size distributions of broadly similar character in widely different landscapes, as found in our examples. We propose that size distributions reflect the systematic scale dependence of the spatially averaged strength. Our results highlight the critical need to constrain the form, amplitude, and wavelength of spatial variability in material strength properties of hillslopes.

Clouds cast shadows on the surface and locally enhance solar irradiance by absorbing and scattering sunlight, resulting in fast and large solar irradiance fluctuations on the surface. Typical spatiotemporal scales and driving mechanisms of this intra‐day irradiance variability are not well known, hence even 1 day ahead forecasts of variability are inaccurate. Here, we use long‐term, high‐frequency solar irradiance observations combined with satellite imagery, numerical simulations, and conceptual modeling to show how irradiance variability is linked to the cloud size distribution. Cloud shadow sizes are distributed according to a power law over multiple orders of magnitude, deviating only from the cloud size distribution due to cloud edge transparency at scales below ≈750 m. Locally cloud‐enhanced irradiance occurs as frequently as shadows, and is similarly driven mostly by boundary layer clouds, but distributed over a smaller range of scales. We reconcile studies of solar irradiance variability with those on clouds, which brings fundamental understanding to what drives irradiance variability. Our findings have implications not only for weather and climate modeling, but also for solar energy and photosynthesis by vegetation, where detailed knowledge of surface solar irradiance is essential. Plain Language Summary: The amount of sunlight received at a given location on the Earth's surface varies on many temporal and spatial scales. Clouds have a large influence on the daily and local scale by creating alternating patterns of shadows and extra bright sunlight, which can fluctuate back and forth multiple times per minute. Weather and climate models do not capture these details, because they are necessarily simplified in order to save computational time. We aim to learn what the typical time and spatial scales of these shadows and sunny patterns are, and where they originate from. Our study is based on 10 yr of detailed sunlight observations, satellite imagery of clouds, and cloud‐resolving atmospheric modeling. We find that horizontal scales in sunlight variability are almost identical to those of clouds. Only at the smallest scales, where clouds are so small that they become transparent, do the observations of sunlight variability deviate from cloud sizes. These observations can be reproduced with a simple model based on the size distributions of clouds. This knowledge could help guide those who try to include sunlight variability in a simple way into their analysis and modeling of, for example, solar energy and photosynthesis. Key Points: Surface solar irradiance variability scales with a power law over multiple orders of magnitude, set by the distribution of cloud sizesBroken and scattered boundary layer clouds cause most of the intra‐day solar irradiance variabilityCloud shadow size can be constructed from cloud size by accounting for cloud edge transparency with an approximate length scale of 25 m [ABSTRACT FROM AUTHOR]

The hardness of high‐strength steel gradually decreases from the subsurface layer to the layer that is half its thickness. This hardness distribution reduces the wear resistance of steel plates. To date, there have been few reported solutions to this problem. Herein, an in situ approach is used to prepare TiC‐reinforced steel. The findings demonstrate that the introduction of TiC reinforcement enhances the wear resistance performance along the thickness direction of high‐strength steel. Although the hardness of TiC‐reinforced steel gradually decreases from the surface to the core, the wear resistance of the steel initially increases before decreasing. In addition, compared with normal steel, the wear resistance performance of TiC‐reinforced steel is increased by 15% at the subsurface, 24% at 1/4 thickness, and 31% at 1/2 thickness. This unusual phenomenon is attributed to the size features of TiC, which vary along the thickness of the plate. The proportion of small TiC particles decreases from the subsurface layer to the core, whereas the proportion of large TiC particles increases gradually. This technique can provide an avenue for improving the wear resistance of other large‐thickness wear‐resistant materials along the thickness direction. [ABSTRACT FROM AUTHOR]

Atmospheric nanoparticles are crucial components contributing to fine particulate matter (PM 2.5), and therefore have significant effects on visibility, climate, and human health. Due to the unique role of atmospheric nanoparticles during the evolution process from gas-phase molecules to larger particles, a number of sophisticated experimental techniques have been developed and employed for online monitoring and characterization of the physical and chemical properties of atmospheric nanoparticles, helping us to better understand the formation and growth of new particles. In this paper, we firstly review these state-of-the-art techniques for investigating the formation and growth of atmospheric nanoparticles (e.g., the gas-phase precursor species, molecular clusters, physicochemical properties, and chemical composition). Secondly, we present findings from recent field studies on the formation and growth of atmospheric nanoparticles, utilizing several advanced techniques. Furthermore, perspectives are proposed for technique development and improvements in measuring atmospheric nanoparticles. [Display omitted]. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) are of interest for next‐generation electronics and optoelectronics owing to their unique optical and electronic functionalities. Although atomically thin flat TMD layers have been investigated in various device applications, pattern‐mediated growth serves great promise for revealing novel properties and application opportunities of TMDs. Herein, controlled size distribution of CVD‐grown monolayer MoS2 flakes by varying the distance between surface pattern features and the effects of patterning on the optical properties of MoS2 domains is reported. Larger flakes and higher uniformity in size distribution are obtained via patterning in comparison with the results from bare surface. Superior photoluminescence (PL) performances are observed for the 2D MoS2 grown on the pattern valleys when compared with the sample on the hill regions and the bare surface. The results demonstrate the notable potential of 2D TMDs for applications in electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

As an implication of their semivolatility, aerosols play a key role in the environmental transport and fate of current-use pesticides (CUPs). Size-segregated PM 10 samples were collected at each one rural, urban residential and coastal site during a pesticide application season. Out of 72 targeted CUPs, the mass size distribution of 48 CUPs was determined. Individual pesticide mass median diameters were found in the submicrometer as well as in the supermicrometer range. The findings suggest that the PM 10 mass size distribution and chemical composition influenced the CUPs mass size distributions. • Aerosol size distributions of 48 current-use pesticides determined, including 25 for the first time. • Size distributions differ across CUPs and peak in both sub- and supermicrometer modes. • Banned CUPs were predominantly found on coarse particles. • In sea spray aerosols, CUPs were predominantly in coarse particles. [ABSTRACT FROM AUTHOR]

This work addresses conflicting results in the literature regarding liquid inclusion agglomeration. To assess whether liquid calcium aluminates do agglomerate in liquid steel, laboratory experiments were performed: melting electrolytic iron, deoxidizing the melt with aluminum and subsequently calcium treating the deoxidation products (alumina and magnesia-alumina spinel inclusions). Under laboratory conditions, solid spinels and alumina inclusions were successfully modified, producing a new population of much smaller calcium aluminate inclusions. The new population of inclusions forms because the presence of calcium in the liquid steel destabilizes alumina and MgO-alumina inclusions, which then dissolve into the melt. The liquid inclusions exhibited a weak but statistically significant tendency to agglomerate. Laboratory results were assessed in the light of different collision mechanisms. Agglomeration mainly occurs by Stokes and laminar fluid flow collision when no external stirring is imposed. Monte Carlo simulations of collisions agree reasonably well with experimental results. For industrial conditions, where the liquid steel is agitated by argon bubbling and/or electromagnetic stirring, turbulent collisions dominate.

Health effects resulting from the smoke of carbonyl compounds (aldehydes and ketones) and metal-containing incense particles at temples during incense burning periods were evaluated at temple A (without incense reduction activities) and B (with incense reduction activities), Nantou County, in 2018. The predominant size fractions of particles were PM1, PM1–2.5, and PM2.5–10 at both temples. The total particle mass at temple A was approximately 1.1 times that of temple B due to incense reduction at temple B. The most abundant metal elements in all particle size fractions at both temples were Fe, Al, and Zn. Metal species of incense smoke are divided into three groups by hierarchical cluster analysis and heatmaps, showing higher metal contents in groups PM1, PM18–10, and PM18–2.5 at temple A. In contrast, higher metal contents were observed in PM18–10 and PM2.5–1 at temple B. Most of the carbonyl species were formaldehyde and acetaldehyde, released during incense burning periods, with concentrations ranging from 6.20 to 13.05 μg/m3 at both temples. The total deposited fluxes of particle-bound metals at temples A and B were determined to be 83.00% and 84.82% using the International Commission on Radiological Protection (ICRP) model. Health-risk assessments revealed that the risk values of metals and carbonyls were above recommended guidelines (10−6) at temple A. Since worshippers and staff are exposed to incense burning environments with poor ventilation over a long period, these toxic organic compounds and metals increase health risks in the respiratory tract. Therefore, incense reduction is important to achieve healthy temple environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Emission factors of multiple PM-bound PTCs from residential combustion was measured. • Most PAHs and derivatives of residential combustion originate from chemical reaction. • Absorption mechanism is the dominant mechanism for gas/particle partitioning of PTCs. • The health risks caused by potential toxic elements in clean coal cannot be ignored. • BaPeq of PM 1 -bound PTCs accounted for 82.91% of that of PM 2.5 on average. Particulate matter (PM) from residential combustion is an existential threat to human health. Emission factors (EFs) of multiple potential toxic components (PTCs) in size-resolved PM and gas from eight residential fuel combustion were measured, and size distribution, gas/particle partitioning and health risks of the PTCs were investigated. Average EFs from clean coal and anthracite coal were PTEs (sum of EFs of 11 Potential Toxic Elements, 6.62 mg/kg fuels) > PAHs (sum of 22 Polycyclic Aromatic Hydrocarbons, 1.12 mg/kg) > OPAHs (sum of 5 Oxygenated Polycyclic Aromatic Hydrocarbons, 0.45 mg/kg) > PAEs (sum of 6 Phthalate Esters, 0.11 mg/kg) > NPAHs (sum of 14 Nitropolycyclic Aromatic Hydrocarbons, 16.84 μg/kg) > OPEs (sum of 7 Organophosphate Esters, 7.57 μg/kg) > PCBs (sum of 6 Polychorinated Biphenyls, 0.07 μg/kg), which were 2–3 and 1–2 orders of magnitude lower than the EFs of PTCs (except PTEs) from bituminous coal and biomass. Most PAHs, OPAHs and NPAHs, which may mainly originate from chemical reactions, showed similar size distributions and averagely 85 % concentrated in PM 1. PTEs, PAEs, OPEs and PCBs generated from the release from raw fuels may have a higher proportion, so their size distributions were more complex and varied with combustion temperature, volatility of compounds, binding mode of the raw fuels, and so on. In addition, clean coal and high-quality anthracite coal could reduce the health risks from the potential organic toxic components, but also reveal the stumbling block of PTEs in risk control. [ABSTRACT FROM AUTHOR]

More than 900 million people worldwide live in slums. These slums mainly can be found in cities of the global south and are characterized by poor living conditions and usually insufficient access to basic infrastructure such as water or energy. In order to improve the living conditions of slum inhabitants, information about the number, location and size of the slums is required to plan supply infrastructure. We therefore identify morphological slums in eight different cities in Africa, South America and Asia, using remote sensing data and analyse their size distributions. We show that 84.6% of all observed morphological slums have a size between 0.001 and 0.1 km2. These results rely on a consistent approach using a clear ontology and conceptual frame for classification. However, classification methods for these underserved areas differ. We show slum classifications based on different methods reveal a strong dependency between the particular method and the resulting size distribution. The study shows the relevance of remote sensing for the investigation of slums and the results can be used for infrastructure planning, as infrastructure improvement projects are often limited to the large known slums. Whereas, the large number of small slums distributed across the city is often neglected.

Microwave heating is a developing noncontact heating method in dewatering technology. It has been proved to be effective to dewater high moisture content in mineral substance via the application of the dielectric loss of materials. In this study, the effects of microwave power levels (250–550 W) and different sample masses (20–40 g) on microwave drying behavior of pyrolusite have been investigated. For the purpose of the mechanism and morphological changes to the pyrolusite in the process of drying, thermogravimetric analysis, scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were used, respectively. The experiment results demonstrated that an increase in the microwave power as well as sample mass was found to increase the drying rate during pyrolusite drying processes, with there are four main mass loss stages from 20 to 900 °C. The SEM-EDS analysis results show that morphological changes with the presence of more pores and appearance in spiral cross-linking way reduced the particle size and the shrinkage of the faces and edges, in which it can been concluded that the microwave drying is an effective method to produce the high-grade pyrolusite. By analysis, the increased pore structure and shrinkage phenomena can be observed, which increase the specific surface area of manganese ore effectively and may benefit the subsequent reduction process of high valence manganese, after the process of microwave heating. [ABSTRACT FROM AUTHOR]

We show the ranges of droplet size reduction depending on the relative velocity before interaction, initial dimensions of each of the droplets and their ratio, as well as the Weber, Ohnesorge, Reynolds, and capillary numbers. Experiments are conducted for water, Diesel fuel emulsion, and castor oil emulsion. The ranges of a prospective increase in the liquid surface area due to droplet collisions as a function of the variable parameters are determined. We single out three Weber variation intervals: <50 (drastic change in the number of child droplets), 50–150 (lower increment rate of the number of child droplets), >150 (the number and dimensions of child droplets remain the same with an increase in the Weber number). The number and average size of child droplets are influenced by the relative velocity of the two parent drops, the ratio of their dimensions, as well as the angular and linear collision parameters. Unlabelled Image • The size of child droplets varies most significantly at We = 50–150. • The greatest number of child droplets can be obtained at B > 0.85. • Maximum child droplets number is provided when the impact angle is 0–15° or 80–90°. • Ratio of the average size of satellite and initial droplets may reach 0.05. • Liquid surface area can be increased by 5–7 times at collision-induced disruption. [ABSTRACT FROM AUTHOR]

Growth is a key attribute influencing population dynamics and fishery production, and understanding factors that affect the growth of individuals in a population is essential in fisheries science and management. This study analyses 18 years of fishery-independent trawl data to determine the relationships among temperature, density, primary productivity and growth of the blue swimmer crab, Portunus armatus , in a temperate marine embayment. Growth was modelled using mixture distribution analyses and cohort-specific seasonal growth curves to estimate the size of crabs at the age of 0.5 and 1.5 years. Growth was highly seasonal, with size-at-age increasing during the austral summer periods and slowing/ceasing during the cooler winter months. The results from the mixture models were used to estimate the mean size of the 0.5- and 1.5-year-old crabs in each year. Linear models showed that the mean size of adult P. armatus at 1.5 years was negatively related to the density of juvenile (0.5 year) crabs in the previous year (i.e. the same cohort) and chlorophyll a concentrations in this year. Increased chlorophyll a levels may increase the survival of larval and megalopal P. armatus , leading to density-dependent effects such as increased competition among juveniles for food and spatial resources, and ultimately, reduced growth. [ABSTRACT FROM AUTHOR]

Cylindrical particles have been widely used in fixed bed reactors for their better mechanical strength by extrusion granulation. The size of cylindrical particle often varies each other in industrial application. How size distributions and packing rates of particles influence the packing structures and flow behaviors in fixed bed are still not clear. In present study, Discrete Element Method (DEM) was employed to simulate packing processes of cylindrical particles. The influences of particle size distributions and packing rates of particles on packing structures of fixed bed were investigated. Subsequently, local fluid flow behaviors and overall pressure drops inside fixed bed were studied in detail by Computational Fluid Dynamic (CFD). It can be found that the wider the size distributions are, the bigger the bed porosities are. Smaller packing rate of particles is beneficial to obtain denser packing beds. The radial porosity distribution is not uniform only near the wall region for wide size distributions. The local non-uniform flow exists and the average axial velocity shows similar distribution tendency with the local porosity. Pressure drops along the bed were obtained based on detailed flow simulations and compared with empirical correlations. The equation parameters were modified for smaller deviations based on the CFD results. The present study gives a detailed understanding of packing process for polydisperse cylindrical particles and the fluid behaviors inside fixed bed, which is very useful for guiding industrial reactor installation and reactor design. Unlabelled Image • Packing processes of polydisperse cylindrical particles were investigated by DEM. • Wider size distribution results in larger porosity than uniform size. • Smaller packing rate of particles is beneficial to obtain denser packing beds. • Local flow behaviors and pressure drops were obtained by CFD method. [ABSTRACT FROM AUTHOR]

Data collected by a ground-based solar spectrometer at Collegeville, MN, was used to generate Aerosol Optical Depths (AODs) throughout the 2017 calendar year. The AOD data was then visualized at 13 selected wavelengths throughout the year and analyzed in comparison to satellite imagery, upper air charts and backwards trajectories of air masses moving towards Central Minnesota in order to determine key dates of interest that correspond to times before (20170615), during (20170729), and at the conclusion of (20170914) forest fires that burned in British Columbia (BC) during the summer of 2017. The data from these specific days were analyzed further by inputting the maximum and minimum AODs for each day into a Parameter Based Particle Swarm Optimization (PBPSO) algorithm in order to generate bimodal lognormal particle size distributions. The bimodal distributions were chosen because they carry more information about the aerosol loads across the entire spectrum of particle radii. The resulting distributions show an increase in number density and decrease in median radius in the Aitken mode during the BC forest fires and a relatively constant (within uncertainty) number density of accumulation mode particles at daily maximum AODs. Comparing the resulting bimodal lognormal distribution for daily minimum AODs (where evaporation and other diurnal effects are at a minimum) shows an increased number density of Aitken mode particles by two orders of magnitude from pre- to postforest fires. This measured increase in the number density of smaller radii particles due to forest fires illustrates the PBPSO's capability of distinguishing variations in atmospheric aerosol particle number size distributions in the Aitken mode based on data collected by the Kipp-Zonen PGS-100 solar spectrometer. [ABSTRACT FROM AUTHOR]

To investigate the influence of pollution events on the chemical composition and formation processes of aerosol particles, 24-h integrated size-segregated particulate matter (PM) was collected during the fall season at an urban site of Gwangju, Korea and was used to determine the concentrations of mass, water-soluble organic carbon (WSOC) and ionic species. Furthermore, black carbon (BC) concentrations were observed with an aethalometer. The entire sampling period was classified into four periods, i.e., typical, pollution event I, pollution event II, and an Asian dust event. Stable meteorological conditions (e.g., low wind speed, high surface pressure, and high relative humidity) observed during the two pollution events led to accumulation of aerosol particles and increased formation of secondary organic and inorganic aerosol species, thus causing PM2.5 increase. Furthermore, these stable conditions resulted in the predominant condensation or droplet mode size distributions of PM, WSOC, NO3 -, and SO4 2-. However, difference in the accumulation mode size distributions of secondary water-soluble species between pollution events I and II could be attributed to the difference in transport pathways of air masses from high-pollution regions and the formation processes for the secondary chemical species. The average absorption Ångström exponent (AAE370-950) for 370-950 nm wavelengths > 1.0 indicates that the BC particles from traffic emissions were likely mixed with light absorbing brown carbon (BrC) from biomass burning (BB) emissions. It was found that light absorption by BrC in the near UV range was affected by both secondary organic aerosol and BB emissions. Overall, the pollution events observed during fall at the study site can be due to the synergy of unfavorable meteorological conditions, enhanced secondary formation, local emissions, and long-range transportation of air masses from upwind polluted areas. [ABSTRACT FROM AUTHOR]

Abstract TSP and 9-stage size-segregated samples were simultaneously collected in Xi'an during the spring of 2013 and analyzed for organic aerosols (OA) on a molecular level. n -Alkanes were the dominant compound class during the whole campaign, followed by fatty acids. High molecular weight (HMW) n -alkanes and fatty acids dominated in the coarse mode particles (>1.1 μm) during the dust event, indicating they were mostly originated from surface soil and plants in the upwind regions. Low-volatile anthropogenic compounds such as benzo (e) pyrene (BeP) and bisphenol A (BPA) dominated in the fine mode particles during the whole campaign. In contrast, semi-volatile anthropogenic compounds such as phenanthrene (Phe) and di- n -butyl phthalates (DBP) showed a bimodal size distribution with a significant increase in the coarse mode during the dust event due to their vaporization from the fine mode particles and the subsequent adsorption on the dust surface. Secondary organic aerosols (SOA) in Xi'an during the dust storm period were predominantly enriched on the coarse particles, which can be ascribed to the adsorption and subsequent oxidation of gas-phase hydrophilic organics on the aqueous-phase of hygroscopic dust surface (e.g., mirabilite). Our work suggested an important role of multiphase reaction in evolution of aerosol chemistry during the dust long-range transport process. Highlights • n -Alkanes were the dominant organic compound class during the whole campaign. • Low-volatile anthropogenic compounds dominated in the fine mode particles. • SOA were predominantly enriched on the coarse particles during the dust storm. • Multiphase reaction has an important role in evolution of aerosol chemistry. [ABSTRACT FROM AUTHOR]

Abstract To identify the sources and heterogeneous reactions of sulfate and nitrate with dust in the atmosphere, airborne particles in Xi'an, inland China during the spring of 2017 were collected and measured for chemical compositions, along with a laboratory simulation of the heterogeneous formation of ammonium nitrate on the dust surface. Our results showed that concentrations of Ca2+, Na+ and Cl− in the TSP samples were enhanced in the dust events, with the values of 41.8, 5.4 and 4.0 μg m−3, respectively, while NO 3 − (7.1 μg m−3) and NH 4 + (2.4 μg m−3) remarkably decreased, compared to those in the non-dust periods. During the dust events, NH 4 + correlated only with NO 3 − (R2 = 0.52) and abundantly occurred in the coarse mode (>2.1 μm), in contrast to that in the non-dust periods, which well correlated with sulfate and nitrate and enriched in the fine mode (<2.1 μm). SO 4 2− in Xi'an during the dust events existed mostly as gypsum (CaSO 4 · 2H 2 O) and mirabilite (Na 2 SO 4 · 10H 2 O) and dominated in the coarse mode, suggesting that they were directly transported from the upwind Gobi Desert region. Our laboratory simulation results showed that during the long-range transport hygroscopic salts in the Gobi dust such as mirabilite can absorb water vapor and form a liquid phase on the particle surface, then gaseous NH 3 and HNO 3 partition into the aqueous phase and form NH 4 NO 3 , resulting in the strong correlation of NH 4 + with NO 3 − and their accumulation on dust particles. The dry deposition flux of total inorganic nitrogen (NH 4 + + NO 3 −) in Xi'an during the dust events was 0.97 mg-N m−2 d−1 and 37% higher than that in the non-dust periods. Such a significant enhanced N-deposition is ascribed to the heterogeneous formation of NH 4 NO 3 on the dust particle surface, which has been ignored and should be included in future model simulations. Graphical abstract Image 1 Highlights • SO 4 2− during the dust events existed mostly as gypsum (CaSO 4 · 2H 2 O) and mirabilite (Na 2 SO 4 · 10H 2 O). • Hygroscopic salts in dust absorb water vapor and form a liquid phase on the particle surface, resulting in the heterogeneous formation of NH 4 NO 3 on the coarse mode particles. • The accumulation of NH 4 NO 3 on the dust particles enhanced the N-deposition. [ABSTRACT FROM AUTHOR]

More than 900 million people worldwide live in slums. These slums mainly can be found in cities of the global south and are characterized by poor living conditions and usually insufficient access to basic infrastructure such as water or energy. In order to improve the living conditions of slum inhabitants, information about the number, location and size of the slums is required to plan supply infrastructure. We therefore identify morphological slums in eight different cities in Africa, South America and Asia, using remote sensing data and analyse their size distributions. We show that 84.6% of all observed morphological slums have a size between 0.001 and 0.1 km2. These results rely on a consistent approach using a clear ontology and conceptual frame for classification. However, classification methods for these underserved areas differ. We show slum classifications based on different methods reveal a strong dependency between the particular method and the resulting size distribution. The study shows the relevance of remote sensing for the investigation of slums and the results can be used for infrastructure planning, as infrastructure improvement projects are often limited to the large known slums. Whereas, the large number of small slums distributed across the city is often neglected. [ABSTRACT FROM AUTHOR]

The goals of the International Global Atmospheric Chemistry (IGAC) Program's First Aerosol Characterization Experiment (ACE 1) are to determine and understand the properties and controlling factors of the aerosol in the remote marine atmosphere that are relevant to radiative forcing and climate. A key question in terms of this goal and the overall biogeochemical sulfur cycle is what factors control the formation, growth, and evolution of particles in the marine boundary layer (MBL). To address this question, simultaneous measurements of dimethylsulfide (DMS), sulfur dioxide (SO2), the aerosol chemical mass size distribution, and the aerosol number size distribution from 5 to 10,000 nm diameter were made on the National Oceanic and Atmospheric Administration (NOAA) ship Discoverer. From these data we conclude that the background MBL aerosol during ACE 1 often was composed of four distinct modes: an ultrafine (UF) mode (Dp  = 5–20 nm), an Aitken mode (Dp  = 20–80 nm), an accumulation mode (Dp  = 80–300 nm), and a coarse mode (Dp  > 300 nm). The presence of UF mode particles in the MBL could be explained by convective mixing between the free troposphere (FT) and the MBL associated with cloud pumping and subsidence following cold frontal passages. There was no evidence of major new particle production in the MBL. Oceanic emissions of DMS appeared to contribute to the growth of Aitken and accumulation mode particles. Coarse mode particles were comprised primarily of sea salt. Although these particles result from turbulence at the air-sea interface, the instantaneous wind speed accounted for only one third of the variance in the coarse mode number concentration in this region.

Continuous measurements of particle number size distributions in the size range from 10 nm to 800 nm were performed from 2015 to 2019 at the ECO Environmental-Climate Observatory of Lecce (Global Atmosphere Watch Programme/Aerosol, Clouds and Trace Gases Research Infrastructure (GAW/ACTRIS) regional station). The main objectives of this work were to investigate the daily, weekly and seasonal trends of particle number concentrations and their dependence on meteorological parameters gathering information on potential sources. The highest total number concentrations were observed during autumn-winter with average values nearly twice as high as in summer. More than 52% of total particle number concentration consisted of Aitken mode (20 nm < particle diameter (Dp) < 100 nm) particles followed by accumulation (100 nm < Dp < 800 nm) and nucleation (10 nm < Dp < 20 nm) modes representing, respectively, 27% and 21% of particles. The total number concentration was usually significantly higher during workdays than during weekends/holidays in all years, showing a trend likely correlated with local traffic activities. The number concentration of each particle mode showed a characteristic daily variation that was different in cold and warm seasons. The highest concentrations of the Aitken and accumulation particle mode were observed in the morning and the late evening, during typical rush hour traffic times, highlighting that the two-particle size ranges are related, although there was significant variation in the number concentrations. The peak in the number concentrations of the nucleation mode observed in the midday of spring and summer can be attributed to the intensive formation of new particles from gaseous precursors. Based on Pearson coefficients between particle number concentrations and meteorological parameters, temperature, and wind speed had significant negative relationships with the Aitken and accumulation particle number concentrations, whereas relative humidity was positively correlated. No significant correlations were found for the nucleation particle number concentrations.

Growth pervades all areas of life from single cells to cell populations to tissues. Cell size often fluctuates significantly from cell to cell and from generation to generation. Here we present a unified framework to predict the statistics of cell size variations within a lineage tree of a proliferating population. We analytically characterize (i) the distributions of cell size snapshots, (ii) the distribution within a population tree, and (iii) the distribution of lineages across the tree. Surprisingly, these size distributions differ significantly from observing single cells in isolation. In populations, cells seemingly grow to different sizes, typically exhibit less cell-to-cell variability and often display qualitatively different sensitivities to cell cycle noise and division errors. We demonstrate the key findings using recent single-cell data and elaborate on the implications for the ability of cells to maintain a narrow size distribution and the emergence of different power laws in these distributions.

Humans emit large salivary particles when talking, singing, and playing musical instruments, which have implications for respiratory disease transmission. Yet little work has been done to characterize the emission rates and size distributions of such particles. This work characterized large particle ( d p > 35 μm in aerodynamic diameter) emissions from 70 volunteers of varying age and sex while vocalizing and playing wind instruments. Mitigation efficacies for face masks (while singing) and bell covers (while playing instruments) were also examined. Geometric mean particle count emission rates varied from 3.8 min -1 (geometric standard deviation [GSD] = 3.1) for brass instruments playing to 95.1 min -1 (GSD = 3.8) for talking. On average, talking produced the highest emission rates for large particles, in terms of both number and mass, followed by singing and then instrument playing. Neither age, sex, CO 2 < 35 μm). Size distributions were similar between talking and singing (count median diameter = 53.0 μm, GSD = 1.69). Bell covers did not affect large particle emissions from most wind instruments, but face masks reduced large particle count emissions for singing by 92.5% (95% CI: 97.9%, 73.7%).d p < 35 μm). Size distributions were similar between talking and singing (count median diameter = 53.0 μm, GSD = 1.69). Bell covers did not affect large particle emissions from most wind instruments, but face masks reduced large particle count emissions for singing by 92.5% (95% CI: 97.9%, 73.7%).

Below‐cloud aerosol scavenging is an important process to remove particles from the atmosphere. In this study, both precipitation (measured with a laser disdrometer registering drops between 0.125 and 8 mm) and atmospheric aerosol particles (measured with a Passive Cavity Aerosol Spectrometer Probe registering aerosol sizes between 0.1 and 24 µm) have been sampled on a 1 min basis. Based on 6 months of outdoor measurements in León (northwest Iberian Peninsula), the scavenging coefficients were calculated for the aerosol particles measured, with a mean value of 2.6 × 10−5 ± 6.0 × 10−5 s−1 for the fine mode and 5.8 × 10−5 ± 9.6 × 10−5 s−1 for the coarse mode in 54 rain events. Likewise, the particle concentration decreased during rain by 10%, and by 18% between the time before and after the rain. In the Greenfield Gap (sizes between 0.3 and 1 µm) the scavenging is less effective, mainly between 0.6 and 1 µm, than with smaller particles. The number of drops between 0.75 and 3 mm shows statistically significant (p < 0.05) negative correlations with the number of particles between 0.16 and 1.76 µm, thus illustrating the potential of those raindrops to favour the scavenging of particles of that size. In addition, there were statistically significant negative correlations between the total volume removed by falling drops (mm3/m3) and the variation of the number of particles in channels with diameters between 0.12 and 0.19 µm. This study focuses on the role of raindrop sizes in the scavenging of aerosol particles based on 6 months of outdoor measurements in León, Spain. Raindrops with diameters between 0.75 and 3 mm produce a higher scavenging on particles between 0.16 and 1.76 µm. The scavenging coefficients had a mean value of 2.6 × 10–5 s–1 for the fine mode and 5.8 × 10–5 s–1 for the coarse mode. [ABSTRACT FROM AUTHOR]

Predators alter abundances and life history characteristics of prey, and effects of predator-prey interactions can be altered by third-party species. Here, we examine size structures of the caddisfly, Phylloicus hansoni, in Trinidadian streams with two distinct fish assemblages: upstream reaches where the predatory killifish, Anablepsoides hartii, is the only fish species (Killifish-Only reaches), and downstream reaches where killifish and the omnivorous guppy, Poecilia reticulata, coexist (Killifish-Guppy reaches). We asked: Do P. hansoni larvae exhibit differences in size structure between reaches with differing fish assemblages? We found that size distributions of larvae differed between reaches in the majority of replicate streams, with smaller median body lengths in Killifish-Only reaches. Killifish-Guppy reaches had higher proportions of the largest instar, but we did not find differences in body length within an instar. No evidence of size-selective predation was found through analysis of killifish stomach contents, and environmental variables were largely similar between upstream and downstream reaches of the five study streams, aside from higher killifish abundances in upstream reaches. Our results, coupled with previous evidence of guppies altering killifish populations, suggest that the mediating effects of a third-party species (guppies) on predator-prey (killifish-caddisfly) interactions can affect the population size structure of prey populations. [ABSTRACT FROM AUTHOR]

Abstract: Tropical convective clouds evolve over a wide range of temporal and spatial scales, which makes them difficult to simulate numerically. Here we propose that cloud statistical properties can be derived within a simplified time‐independent coordinate system of cloud number n, saturated static energy h⋆, and cloud perimeter λ. Under the constraint that circulations around cloud edge compete with each other for total buoyant energy and air, we show that the product of cloud number and cloud perimeter nλ is invariant with λ and that cloud number follows a negative exponential with respect to cloud‐edge deviations of h⋆ with respect to the mean. Overall, the summed perimeter of all clouds scales as the square root of the atmospheric static stability. These theoretical results suggest that the complexity of cloud field structures can be viewed statistically as an emergent property of atmospheric bulk thermodynamics. Comparison with a detailed tropical cloud field simulation shows general agreement to within ≤13%. For the sake of developing hypotheses about cloud temporal evolution that are testable in high resolution simulations, the shapes of tropical cloud perimeter distributions are predicted to be invariant as climate warms, although with a modest increase in total cloud amount. [ABSTRACT FROM AUTHOR]

The control of the wet agglomeration processes of powders depends on the contribution of the characteristics of the native powders. The objective of this work is to specifically investigate the contribution of the size distribution (d 50 and span) and composition (the protein contents) of the native particles, on the dimensional and structural characteristics of the wet agglomerates. Different fractions of native semolina with contrasted size properties (d 50 and span) and protein content are used as raw materials. The wet granulation is conducted using a low shear granulator and liquid spraying condition at constant dimensionless spray flux. The structure properties are evaluated by the distribution of the measured values of the size, water content and compactness. We observed specific effects of the span and the median diameter of native powders on the size distributions of the wet agglomerates. Using small native particles (d 50 < 250 μm) improves the homogeneity of the size distributions. Using slightly dispersed native particles (span < 1.0) leads to a better uniformity on the size distributions. Using semolina with high protein content could lead to a narrow size distribution by limiting the process of fragmentation and the formation of fragments in the bed. We showed that the mechanisms involved in the agglomeration process are similar whatever the size distribution and the protein content of the native powders. [ABSTRACT FROM AUTHOR]

The health effects of metal-containing carbon black (CB) particles obtained from the CB feeding area of a tire manufacturing plant were investigated. Atmospheric samples were collected over 24 h for 20 working days in 2016 using the 12 impaction stages of micro-orifice uniform deposit impactor, and metal-containing particles were analyzed using an inductively coupled plasma optical emission spectrometer. The concentration of total particulate matter in the CB feeding area was 944.8 ± 456.4 μg/m, and the most abundant elements in the samples include Zn (8622.0 ± 5679.0 ng/m), Al (3113.3 ± 2017.1 ng/m), and Fe (1519.1 ± 875.0 ng/m). Carcinogenic metals (Cd, Co, Cr, and Ni) with the mass median diameter were incorporated in submicron particles. The mean total deposition flux in the head airway (HA) region was approximately 16-30 times higher than that in the tracheobronchial (TB) region and alveolar region (AR). The most abundant deposition flux of heavy metals in the AR and TB region was distributed in particles of less than 3.2 μm. The cancer risk presented by carcinogenic metals (Cd, Co, Cr, and Ni) in total particles to CB feeding workers ranged from 5.52 × 10 to 5.65 × 10, which is substantially higher than the acceptable cancer risk range 10-10. In particular, the cancer risk presented by these four metals in ultrafine particles (UFPs) exceeded the 10 benchmark level. These results demonstrate the high health risk presented by particle-bound heavy metals to workers in a CB feeding area via inhalation exposure. [ABSTRACT FROM AUTHOR]

A synthetic set of aerosol optical depths (AODs) generated from a standard set of aerosol size distributions was analyzed by a parameter based particle swarm optimization (PBPSO) routine in order to test the reproducibility of the results. Junge and lognormal size distributions were consistently reproduced. Gamma and bimodal distributions showed large variability in solutions. χ-2 values were used to determine the best subset of possible solutions allowing quantification of parameters with uncertainties when using PBPSO. AODs measured by a sun photometer on a clear day (20160413) and a foggy day (20160508) were then processed by the PBPSO program for both bimodal and lognormal distributions. Results showed that in general the foggy day has smaller χ-2 values indicating that the PBPSO algorithm is better able to match AODs when there is a larger aerosol load in the atmosphere. The bimodal distribution from the clear day best describes the aerosol size distribution since the χ-2 values are lower. The lognormal distribution best describes the aerosol size distribution on the foggy day (20160508). [ABSTRACT FROM AUTHOR]

The French national project MERMOSE gathers the capabilities of seven organizations to better characterize commercial aircraft engine emissions and to better understand their impact on nucleation processes in the atmosphere. In this frame, a measurement campaign has been performed on a Snecma/NPO Saturn SaM146-1S17 turbofan. During this work, we used a complete set of on-line and off-line techniques to measure radial and angular profiles of particulate matter (PM) properties in the engine exhaust hot flow. We studied different engine thrust settings, selected to match the aircraft main operating conditions (idle, climb, take-off, approach and “ground” cruise). The mode of the emitted particles size distribution ranged from 17 nm to 55 nm and was sensitive to the thrust. The sampled PM showed a complex morphology and were formed by primary nanoparticles of about 15 nm in diameter. They were mainly composed of carbon (with traces of oxygen, sulfur and calcium) and their organic carbon to total carbon ratio (OC/TC) ratio showed a decrease as a function of the maximum thrust from ~80% for 30% thrust setting to ~12% for 100%. [ABSTRACT FROM AUTHOR]