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Workers' health is jeopardized in steel rolling workshops due to the production of particulate matter. These particles' physicochemical properties have a direct impact on their effects on human health, emphasizing the importance of understanding these properties for exposure control. This study investigated particulate matter emissions in hot and cold steel rolling workshops, focusing on mass concentrations, particle size distributions, and elemental compositions. The findings revealed that particles predominantly range from 0.3 to 1.0 μm in size, with irregular block-like and fibrous morphologies. Elemental analysis showed distinct compositions: the main components in the hot rolling workshop were oxygen, calcium, silicon, carbon, and iron while those in the cold rolling workshop were oxygen, silicon, aluminum, carbon, and iron. The particulate matter concentrations were higher in the hot rolling workshop than in the cold rolling workshop. The Rosin–Rammler particle size distribution function was applied to characterize particle size distribution at emission sources. This paper highlights the dynamic variations and spatial distribution patterns of particulate matter during rolling processes, providing key data for understanding particulate matter behavior in industrial environments and informing targeted pollution control strategies. [ABSTRACT FROM AUTHOR]

This paper is devoted to the analysis of blow-up solutions for the generalized Hartree equations. To begin with, we derive the sharp threshold of global existence and blow-up. Next, we demonstrate the mass concentration properties and the limiting behavior of blow-up solutions. Furthermore, we establish the nonexistence of minimal mass blow-up solutions by using the limiting behavior of blow-up solutions. [ABSTRACT FROM AUTHOR]

Dredged sediments, which are mud suspensions with concentrations exceeding the gelling point, are utilised in reclamation and Building with Nature projects. Beyond the gelling point, flocs occupy space and begin to form a network structure. This study investigates the impact of initial conditions, specifically the concentration above the gelling point and the stress state, on the consolidation of dredged sediment. The sediment from Lake Markermeer in the Netherlands was studied, specifically in the context of the construction of the Marker Wadden wetland. Material parameters were determined using two distinct experimental methods: settling columns and Seepage Induced Consolidation (SIC) tests. The differences observed between the two sets of material parameters suggest that the stress history and plastic deformation during mixing may influence the results. These effects were analysed using a one-dimensional vertical (1DV) consolidation model. The computed profiles were then compared with the profiles measured using an Ultrasonic High Concentration Meter. An initial concentration of 558.1 g/l, achieved by remixing the equilibrium profile of a normally consolidated suspension, resulted in larger final densities and a lower sediment-water interface. Conversely, a concentration of 175.6 g/l, achieved by remixing consolidating dredged sediment, yielded the same equilibrium layer thickness and density profile as virgin consolidation, albeit after a longer consolidation time. These findings are particularly relevant for land reclamation and wetland construction projects, where the initial density may be high and the dredging process's mixing may alter the stress state. [ABSTRACT FROM AUTHOR]

As the wealth of evidence grows as to the negative impact of indoor air quality on human health, it has become increasingly urgent to investigate and characterise sources of air pollution within the home. Fine particulate matter with a diameter of 2.5 µm or less (PM2.5) is a key cause for concern, and cooking is known to be one of the most significant sources of domestic PM2.5. In this study, the aim was to demonstrate the efficacy of combining experimental techniques and cutting-edge High-Performance Computing (HPC) to characterise the dispersion of PM2.5 during stir-frying within a kitchen laboratory. This was carried out using both experimental measurement with low-cost sensors and high-fidelity Computational Fluid Dynamics (CFD) modelling, in which Lagrangian Stochastic Methods were used to model particle dispersion. Experimental results showed considerable spatio-temporal variation across the kitchen, with PM2.5 mass concentrations in some regions elevated over 1000 μg m − 3 above the baseline. This demonstrated both the impact that even a short-term cooking event can have on indoor air quality and the need to factor in such strong spatio-temporal variations when assessing exposure risk in such settings. The computational results were promising, with a reasonable approximation of the experimental data shown at the majority of monitoring points, and future improvements to and applications of the model are suggested. [ABSTRACT FROM AUTHOR]

Fuxin is located in the atmospheric channel around Bohai Bay, and its geographical location is very special. Few existing studies have investigated the pollution characteristics and health risk assessment of heavy metals in atmospheric PM2.5 during the four seasons in Fuxin, so a total of 180 PM2.5 samples were collected from four sampling sites in Fuxin from December 2021 to November 2022. The seasonal distribution characteristics of V, Cr, Mn, Co, Ni, Cu, Zn, Pb, As, Sb, Cd and Ba were analysed via inductively coupled plasma-mass spectrometry (ICP‒MS), and the source of the heavy metals was analysed via the enrichment factor (EF) and principal component analysis (PCA). A health risk model was used to assess the health risk of respiratory exposure in men, women and children in Fuxin. The results revealed that the annual average mass order of heavy metals in Fuxin PM2.5 was Zn (0.2947 μg·m−3) > Pb (0.0664 μg·m−3) > As (0.0225 μg·m−3) > Ba (0.0205 μg·m−3) > Mn (0.0187 μg·m−3) > Cu (0.0140 μg·m−3) > Cr (0.0095 μg·m−3) > V (0.0067 μg·m−3) > Ni (0.0061 μg·m−3) > Sb (0.0024 μg·m−3) > Cd (0.0019 μg·m−3) > Co (0.0007 μg·m−3). The annual average concentration of As was 3.75 times the GB3095-2012 (China) secondary standard limit, and the concentration of hazard quotient (HQ) in PM2.5 was lower than 1, but the concentration of incremental lifetime cancer risk (ILCR) in As was higher than the cancer risk threshold (10–4). These findings indicate a certain risk of cancer in the urban population of Fuxin. Therefore, it is necessary to control the emissions created from coal burning to minimize the health risks to the people of Fuxin. [ABSTRACT FROM AUTHOR]

We study the two-spinless mass-critical Fermi systems with attractive interactions and trapping potentials. We prove that ground states of the system exist, if and only if the strength a of attractive interactions satisfies 0 < a < a 2 ⁎ , where 0 < a 2 ⁎ < + ∞ is the best constant of a dual finite-rank Lieb-Thirring inequality. By the blow-up analysis of many-fermion systems, we show that ground states of the system concentrate at the flattest minimum points of the trapping potential V (x) as a ↗ a 2 ⁎. [ABSTRACT FROM AUTHOR]

Abstract Brass bands that include wind instruments are heavily affected by rules established during the pandemic. The aim of this experimental work was to assess the aerosols emitted through different wind instruments. The Aerodynamic Particle Sizer (APS) was used to measure the aerosols emitted and transmit those characteristics to a database. The results revealed that the dynamic level at which a note is produced, regardless of whether it is a clarinet, trumpet, or bassoon, significantly changes in aerosol concentrations emitted. Specifically, if there is a higher dynamic level, an increase in emissions of particle concentration will occur by comparing the levels piano, mezzo forte, and forte. These aerosols are produced with a diameter of approximately 0.8 μm, except for the Navarra bagpipe, which has a diameter of 1.8 μm. In addition, this last instrument is the one that emits more particles every second, reaching a value five times larger than that with two reeds, such as the bassoon. Staccato and legato are two well-known techniques among musicians that help in articulating a musical piece. The difference between the two methods in terms of the concentration of the number of particles is not remarkable and is almost negligible.

During the production process in a lead zinc flotation plant, a large amount of particulate matter is generated, polluting the working environment. This study takes a lead zine mine as an example and analyzes the distribution of particulate matter concentration inside and outside the flotation plant. The pollution status and its health impacts are thoroughly investigated. The results show that the quantity concentration of particulate matter smaller than 10 µm inside the average plant is higher than outside, with the quantity concentration increasing as particle size decreases. The average ratio of quantity concentration of particulate matter inside to outside the plant is generally greater than 1. The mass concentrations of PM10, PM2.5, and PM1, inside the plant are significantly higher than those outside, with PM10 and PM2.5 inside the plant exceeding the Grade 1 standard by 5.333 times and 6.313 times, respectively, and the Grade 2 standard by 2.614 times and 2.134 times. The concentration of particulate matter inside the plant significantly influences the concentration outside. The distribution and concentration of particulate matter vary, and environmental factors greatly impact dust pollution. The study's findings provide valuable data for effectively controlling particulate matter in mining environments. [ABSTRACT FROM AUTHOR]

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Dredged sediments, which are mud suspensions with concentrations exceeding the gelling point, are utilised in reclamation and Building with Nature projects. Beyond the gelling point, flocs occupy space and begin to form a network structure. This study investigates the impact of initial conditions, specifically the concentration above the gelling point and the stress state, on the consolidation of dredged sediment. The sediment from Lake Markermeer in the Netherlands was studied, specifically in the context of the construction of the Marker Wadden wetland. Material parameters were determined using two distinct experimental methods: settling columns and Seepage Induced Consolidation (SIC) tests. The differences observed between the two sets of material parameters suggest that the stress history and plastic deformation during mixing may influence the results. These effects were analysed using a one-dimensional vertical (1DV) consolidation model. The computed profiles were then compared with the profiles measured using an Ultrasonic High Concentration Meter. An initial concentration of 558.1 g/l, achieved by remixing the equilibrium profile of a normally consolidated suspension, resulted in larger final densities and a lower sediment-water interface. Conversely, a concentration of 175.6 g/l, achieved by remixing consolidating dredged sediment, yielded the same equilibrium layer thickness and density profile as virgin consolidation, albeit after a longer consolidation time. These findings are particularly relevant for land reclamation and wetland construction projects, where the initial density may be high and the dredging process’s mixing may alter the stress state.

In this paper, we study the L²-critical Hartree equation with harmonic potential which arises in quantum theory of large system of nonrelativistic bosonic atoms and molecules. Firstly, by using the variational characteristic of the nonlinear elliptic equation and the Hamilton conservations, we get the sharp threshold for global existence and blow-up of the Cauchy problem. Then, in terms of a change of variables, we first find the relation between the Hartree equation with and without harmonic potential. Furthermore, we prove the upper bound of blow-up rate in R³ as well as the mass concentration of blow-up solution for the Hartree equation with harmonic potential in RN. [ABSTRACT FROM AUTHOR]

The results of continuous observations of the mass concentration of black carbon (BC) and PM10 and PM2.5 aerosols in the near-surface layer of the atmosphere in the center of Moscow metropolis in 2022 are considered. The results are interpreted applying meteorological data, backward trajectories of air mass transport to Moscow, and MERRA-2 reanalysis data on the spatial distribution of dust and BC in near-surface air of the center of European Russia. The days (less than 9%) of an extreme increase in BC and PM10 concentrations due to atmospheric transport of fire aerosols or dust to Moscow from other regions are highlighted. The variability of a typical aerosol (outside of such episodes) in the megalopolis has been studied at different time scales—from daily to monthly and seasonal. The main contribution of dust and carbon-containing aerosols to megalopolis atmosphere is made by local anthropogenic sources (transport, thermal energy, industrial enterprises, and construction facilities). A high correlation has been established between the concentrations of BC and PM2.5 particles in daily and seasonal changes. Data on BC, PM2.5, and PM10 air pollution in large cities around the world show that Moscow has no more aerosol pollution than the largest cities in Europe and North America. [ABSTRACT FROM AUTHOR]

Let a > 0 , b > 0 and V (x) ≥ 0 be a coercive function in R 2 . We study the solutions with normalized L 2 -norm for the following Kirchhoff type equation - a + b ∫ R 2 | ∇ u | 2 d x Δ u + V (x) u = β | u | 2 u + λ u on a suitable weighted Sobolev space H = u ∈ H 1 (R 2) : ∫ R 2 V (x) u 2 d x < ∞. Our aim is to investigate the limit behaviors of the solutions with normalized L 2 -norm for this equation as (a , b) → (0 , 0) . Moreover, the uniqueness of the solution with normalized L 2 -norm for this equation is also discussed for a, b close to 0 [ABSTRACT FROM AUTHOR]

We devote to the analysis of blow-up solutions for the nonlinear Schrödinger equation with inhomogeneous perturbation. Firstly, we get the sharp threshold of global existence and blow-up for the Cauchy problem. Then, we show the mass concentration properties and the limiting behavior of blow-up solutions. At last, we prove the nonexistence of the minimal mass blow-up solution by using the limiting behavior of blow-up solutions. [ABSTRACT FROM AUTHOR]

It is shown that surfacing with feeding Nano oxides or Nano carbides into the weld pool leads to significant increase the wear resistance of deposited metal. Meanwhile, the information available in the literature on the optimal concentrations of Nano components corresponds only to specific surfacing conditions. Other surfacing conditions require additional experimental studies to determine optimal concentrations under these new conditions. Theoretical studies revealed that a change in the heat input of surfacing is accompanied by a change in the volume and mass of the weld pool, which leads to the changes in the mass concentrations of Nano components. It is shown that, the volume and mass of the weld pool may change almost by 3 times, and the mass percentage of Nano components by 2 times A method has been proposed for determining the mass fraction of Nano components in the weld pool at different heat inputs of surfacing. The experimental studies confirmed analytical predictions. The use of the proposed technique will make it possible to spread the technology of surfacing with feeding of Nano components into the weld pool without additional experimental studies. [ABSTRACT FROM AUTHOR]

Protection from nuclear biochemical aerosol and air pollution pays attention to aerosol mass concentration. The concentration of upstream aerosol of the commonly used filtration efficiency detection device for high-efficiency filter materials is low, making it insufficient for detecting the filtration efficiency of high-efficiency filter materials. This study designed and built a set of filtration efficiency detection devices for high-efficiency filter materials based on mass concentration. By adjusting the oil bath temperature, injection pressure, the degree of spiral-separator separation, as well as the number and size of nozzles, we investigated the effects of each condition on the concentration and particle size distribution of aerosol generation. As a result, the oil mist generator of the device can stably generate high-concentration aerosol with a mass concentration of up to 1587.9 mg/m3 and a number concentration of up to 107–108 P/cm3. The high-concentration aerosol generated can meet the E11–U15 filter material performance requirements. [ABSTRACT FROM AUTHOR]

Although most source apportionments of VOCs use mixing ratios, about 23 % of published studies use mass concentrations. Thus, systematically exploring the changes in VOC source apportioned results caused by metric differences is important to assess the differences in key precursor apportionment results given the observed increases in O3 pollution situation. Different monitoring instruments measured hourly VOC volumetric concentrations in three typical Chinese cities (i.e., Qingdao, Shijiazhuang, and Zhumadian). Converting volumetric to mass concentrations under standard and/or actual temperature–pressure conditions, VOC values with different metrics were obtained. The impacts of different metrics on the source apportionments were then investigated. Compared to the positive matrix factorization of the volumetric data (VC-PMF), the VOC species concentrations with low relative molecular mass (RMM) in the factor profiles substantially decreased in mass data analyses (MC-PMF). However, those species with high RMM substantially increased. There were no substantial differences in the apportioned source contributions based on standard and actual condition mass concentrations. However, the high-low rankings of percent contributions apportioned using the volumetric and mass data produced substantial differences. Compared with the VC-PMF results, the percent contributions of sources dominated by species with low RMM (e.g., natural gas usage and mixed sources containing natural gas usage) apportioned by MC-PMF decreased, while those of sources that emitted high RMM species (e.g., solvent usage and mixed sources containing solvent usage) increased. Source apportionments based on the volumetric concentration data had more practical significance compared to the mass concentration data results for control strategy development since the mass data analyses created issues.

We developed a single-particle optical particle counter with polarization detection (SOPC) for the real-time measurement of the optical size and depolarization ratio (defined as the ratio of the vertical component to the parallel component of backward scattering) of atmospheric particles, the polarization ratio (DR) value can reflect the irregularity of the particles. The SOPC can detect aerosol particles with size larger than 500 nm and the maximum particle count rate reaches ∼1.8 × 105 particles per liter. The SOPC uses a modulated polarization laser to measure the optical size of particles according to forward scattering signal and the DR value of the particles by backward S and P signal components. The sampling rate of the SOPC was 106 #/(sec·channel), and all the raw data were processed online. The calibration curve was obtained by polystyrene latex spheres with sizes of 0.5-10 µm, and the average relative deviation of measurement was 3.96% for sub 3 µm particles. T-matrix method calculations showed that the DR value of backscatter light at 120° could describe the variations in the aspect ratio of particles in the above size range. We performed insitu observations for the evaluation of the SOPC, the mass concentration constructed by the SOPC showed good agreement with the PM 2.5 measurements in a nearby state-controlled monitoring site. This instrument could provide useful data for source appointment and regulations against air pollution. [ABSTRACT FROM AUTHOR]

Emissions from thermal power plants have always been the central consideration for environmental protection. Existing optical sensors in thermal power plants usually measure the total mass concentration of the particulate matter (PM) by a single-wavelength laser, bearing intrinsic errors owing to the variation in particle size distribution (PSD). However, the total mass concentration alone cannot characterize all the harmful effects of the air pollution caused by the power plant. Therefore, it is necessary to measure the mass concentration and PSD simultaneously, based on which we can obtain multi-particle-size channel mass concentration. To achieve this, we designed an optical sensor based on the three-wavelength technique and tested its performance in a practical environment. Results showed that the prototype cannot only correctly measure the mass concentration of the emitted PM but also determine the mean diameter and standard deviation of the PSDs. Hence, the mass concentrations of PM10, PM2.5, and PM1 are calculated, and the air pollutants emission by a thermal power plant can be estimated comprehensively. [ABSTRACT FROM AUTHOR]

Abstract Nano-to-micron-sized coal dust can cause coal workers’ pneumoconiosis (CWP), and cutting and drilling are the main coal dust-generating processes. Based on a self-developed simulated coal cutting and drilling dust generation system, the effects of cutting parameters (tooth tip cone angle, impact angle, roller rotary speed, cutting speed) and drilling parameters (drill bit diameter, drilling speed) on the mass concentration distribution, number concentration distribution and fractal dimension of 10 nm – 10 μm coal dust were investigated. Results show that the mass concentration of 10 nm – 10 μm coal dust generated by cutting/drilling peak at 5.7 – 7.2 μm, while the number concentrations during cutting and drilling respectively peak at 60 – 90 nm and 20 – 30 nm. During both cutting and drilling processes, the generated coal dust particles in 10 – 300 nm account for > 90% of the total 10 nm – 10 μm coal particles, while PM2.5 in PM10 is generally below 18%. It is also found that smaller tooth tip cone angle, larger impact angle, lower roller rotary speed, smaller drill bit diameter, or lower drilling speed can reduce the generation of 10 nm – 10 μm coal dust with a fractal dimension of 0.94 – 1.92. This study reveals the distribution characteristics of nano- to micron-sized coal dust particles under different cutting and drilling parameters, and the research results can serve as reference for adjusting cutting and drilling parameters to lower down the 10 nm – 10 μm coal dust generation and thus prevent the CWP.

In the current paper, the Cauchy problem for the inhomogeneous nonlinear Schrödinger equation including inverse-square potential is considered. First, some criteria of global existence and finite-time blow-up in the mass-critical and mass-supercritical settings with $ 0 < c\leq c^{*} $ are obtained. Then, by utilizing the potential well method and the sharp Sobolev constant, the sharp condition of blow-up is derived in the energy-critical case with $ 0 < c < \frac{N^{2}+4N}{(N+2)^{2}}c^{*} $. Finally, we establish the mass concentration property of explosive solutions, as well as the dynamic behaviors of the minimal-mass blow-up solutions in the $ L^{2} $-critical setting for $ 0 < c < c^{*} $, by means of the variational characterization of the ground-state solution to the elliptic equation, scaling techniques and a suitable refined compactness lemma. Our results generalize and supplement the ones of some previous works.

Enormous amount of protective masks was consumed in connection with the COVID-19 pandemic and they still burden the environment. Therefore, it is necessary to look for possibilities of their disposal in an ecologically acceptable way. This article focuses on particulate matter produced concerning the energy disposal of pandemic FFP2 masks. These masks were processed into small pieces, added to spruce and beech wood (in the weight proportion 5 % and 10 % of FFP2 masks) and formed into pellets. The concentration of particulate matter formed during their combustion was measured by the gravimetric method. The inorganic elements were detected from filters with captured particulate matter by an energy-dispersive X-ray fluorescence spectrometer and verified by inductively coupled plasma-optical emission spectroscopy. It was found that higher concentrations of particulate matter were recorded predominantly with a higher mass airflow. In both airflows (40 % and 50 %), beech pellets had a higher mass concentration than spruce pellets probably caused by the presence of bark in beech wood. Based on the chemical composition, the following elements in small amounts (0–2 mg on a filter) were identified: K, S, Cl and Fe. High concentrations of harmful elements carried in particulate matter have not been detected. FFP2 masks added in a small percentage (up to 10 %) can be used in wood pellets for combustion purposes without significantly affecting the combustion process.

Toxicological data and exposure levels of fine particulate matters (PM2.5) are necessary to better understand their health effects. Simultaneous measurements of PM2.5 oxidative potential (OP) and cell toxicity in urban areas (Beijing, China and Gwangju, Korea) reveal their dependence on chemical composition. Notably, acids (Polar), benzocarboxylic acids, and Pb were the chemical components that affected both OP and cell toxicity. OP varied more significantly among different locations and seasons (winter and summer) than cell toxicity. Using the measured OP, cell toxicity, and PM2.5 concentration, a health index was developed to better assess the potential health effects of PM2.5. The health index was related to the sources of PM2.5 derived from the measured chemical components. The contributions of secondary organic aerosols and dust to the proposed health index were more significant than their contributions to PM2.5 mass. The developed regression equation was used to predict the health effect of PM2.5 without further toxicity measurements. This new index could be a valuable health metric that provides information beyond just the PM2.5 concentration level.

This article considers the formation of singularity in the one-dimensional isentropic drift-flux system of two-phase flow with the generalized Chaplygin gas. We give an appropriate initial condition that results in the formation of singularity in finite time. Notably, the formation of singularity is accompanied by the concentration of mass. Furthermore, we verify the theoretical results. [ABSTRACT FROM AUTHOR]

We deal with the attractive Bose–Einstein condensates with sinusoidal potential in a circular region S : = { x : 0 ≤ | x | ≤ π } ⊂ R 2 . The existence, non-existence and mass concentration behavior (i.e., blow-up) of constrained minimizers for the related Gross-Pitaevskii energy functional are analyzed. Once the blow-up behavior arises, we prove that the mass of positive minimizers must concentrate at center of the circular region, rather than the points of circumference. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of temporal variations in the concentration of microparticles in the surface layer of the Earth in summer. As initial data, we used the results of instrumental observations of the mass concentration of microparticles with sizes less than 2.5 μm (PM2.5) and meteorological parameters in the atmospheric surface layer for the summer period of 2021 and 2022, obtained at the mid-latitude Mikhnevo Geophysical Observatory of Sadovsky Institute of Geopshere Dynamics of Russian Academy of Sciences. In the course of data processing and analysis, diurnal variations in air temperature and PM2.5 were determined. A strong correlation was established between the average daily temperature and PM2.5, both for individual months and the summer period as a whole. In August 2022, the factor that had a significant impact on PM2.5 was forest fires in Ryazan oblast. [ABSTRACT FROM AUTHOR]

Nano-to-micron-sized coal dust can cause coal workers' pneumoconiosis (CWP), and cutting and drilling are the main coal dust-generating processes. Based on a self-developed simulated coal cutting and drilling dust generation system, the effects of cutting parameters (tooth tip cone angle, impact angle, roller rotary speed, cutting speed) and drilling parameters (drill bit diameter, drilling speed) on the mass concentration distribution, number concentration distribution and fractal dimension of 10 nm – 10 μm coal dust were investigated. Results show that the mass concentration of 10 nm – 10 μm coal dust generated by cutting/drilling peak at 5.7 – 7.2 μm, while the number concentrations during cutting and drilling respectively peak at 60 – 90 nm and 20 – 30 nm. During both cutting and drilling processes, the generated coal dust particles in 10 – 300 nm account for > 90% of the total 10 nm – 10 μm coal particles, while PM2.5 in PM10 is generally below 18%. It is also found that smaller tooth tip cone angle, larger impact angle, lower roller rotary speed, smaller drill bit diameter, or lower drilling speed can reduce the generation of 10 nm – 10 μm coal dust with a fractal dimension of 0.94 – 1.92. This study reveals the distribution characteristics of nano- to micron-sized coal dust particles under different cutting and drilling parameters, and the research results can serve as reference for adjusting cutting and drilling parameters to lower down the 10 nm – 10 μm coal dust generation and thus prevent the CWP. [ABSTRACT FROM AUTHOR]

In the current paper, the Cauchy problem for the inhomogeneous nonlinear Schrödinger equation including inverse-square potential is considered. First, some criteria of global existence and finite-time blow-up in the mass-critical and mass-supercritical settings with 0 < c ≤ c ∗ are obtained. Then, by utilizing the potential well method and the sharp Sobolev constant, the sharp condition of blow-up is derived in the energy-critical case with 0 < c < N 2 + 4 N (N + 2) 2 c ∗ . Finally, we establish the mass concentration property of explosive solutions, as well as the dynamic behaviors of the minimal-mass blow-up solutions in the L 2 -critical setting for 0 < c < c ∗ , by means of the variational characterization of the ground-state solution to the elliptic equation, scaling techniques and a suitable refined compactness lemma. Our results generalize and supplement the ones of some previous works. [ABSTRACT FROM AUTHOR]

Data from continuous observations of aerosol composition in the surface atmosphere in Moscow (in the city center) and in Moscow oblast (near the city of Zvenigorod) for three years, from the fall of 2019 to the end of 2022, are analyzed. The data were compared with the results of observations at the Moscow network of stations of the State Budgetary Institution Mosecomonitoring. The concept of conditional background aerosol pollution of the near-surface atmosphere in Moscow has been introduced for those days when the daily mean mass concentration of PM10 particles was below the maximum permissible concentration (MPC) (60 μg/m3). The number of such days exceeded 91% in Moscow over three years of observations. Previously, the authors found that all episodes of higher aerosol pollution of urban air (exceeding the MPC) are associated either with the presence of a close local source in the city or with the long-distance transport of combustion aerosols and/or dust to Moscow and its suburbs from other regions. The daily mean concentration of PM2.5 in the city and the suburb is year-round below the MPC (35 μg/m3). The conditional background aerosol pollution of the surface atmosphere is formed by both natural and anthropogenic sources of aerosols, not only of local, but also of remote origin. Its level and composition implicitly reflect the influence of meteorological parameters on the sources and sinks of aerosols and also the influence of advective transport of aerosol by air masses to and from the city. The results of analysis of seasonal variations in various indicators of aerosol composition in the surface atmosphere under conditional background pollution are presented: the mass concentration of PM10 and PM2.5 particles and individual chemical elements and the distribution of chemical elements by size of aerosol particles. Similarities and differences between these characteristics in the surface air of the city and the suburb in different seasons are specially emphasized. [ABSTRACT FROM AUTHOR]

Results of experimental studies of aerosol in the surface air layer in the southeastern part of the Crimean Peninsula at the background environmental monitoring Vyazemsky Karadag Scientific Station from March 21 to June 17, 2020, are presented. The daily average mass concentration of aerosol ranged from 3 to 35 μg/m3 over the measurement period, with an average value of 13 μg/m3. The exception are high concentrations during the episode of March 25–27, 2020 (48, 195, and 49 μg/m3, respectively), when an extreme eastward transfer from sources in Kazakhstan (a dust storm in the region of the Aral Sea) through Kalmykia to the Crimea took place. Accounting this episode, the daily average mass concentration of aerosol was 16 μg/m3. Days with different directions of airmass arrival and days with the highest daily average mass concentrations of aerosol are distinguished out of 89 observation days. For this set (31 samples), the concentrations of 64 chemical elements in the samples are determined. Accumulation of chemical elements in soil and in aerosol particles is estimated; the clarkes of concentrations of chemical elements in soil, aerosol concentration coefficients, and enrichment factors of chemical elements in aerosols are calculated. The dependences of the mass concentration, size distribution, and elemental composition of the surface aerosol on long-range aerosol transport are considered. [ABSTRACT FROM AUTHOR]

The outcome of the first tests of a measuring system designed for the monitoring of atmospheric aerosol and meteorological parameters is considered. Based on the measurement results from August 2022, the data of the system prototypes, a calibrated optical aerosol sensor, and the on-site meteorological station are compared. The revealed drawbacks of the system design are described. The plans to improve and extend the system capabilities are discussed. A blueprint of a future multipoint aerosol monitoring network in Yekaterinburg and its neighborhood is presented. [ABSTRACT FROM AUTHOR]

The results of experimental determination of near-surface aerosol density for particles of different composition and size have been published over many years. Based on the generalization of these data, as well as the results of our own field observations of microphysical characteristics and composition of Moscow aerosol, an algorithm and parameters for numerical estimation of mass concentration of submicron and micron urban aerosol are suggested. Using this algorithm, on the basis of experimental data on the size distribution function of aerosol particles in the diameter range 0.3–10 μm obtained during regular observations at IAP RAS in Moscow in 2020–2022, the mass concentration of near-surface aerosol of various fractions was calculated. A comparative analysis of the results of such an assessment and the data of synchronous measurements of mass concentration of aerosol particles using a portable aerosol spectrometer GRIMM 1.108 over the past two years has shown a good correspondence between the calculated and measured values. Density values for four ranges of aerosol particle sizes are selected for more correct numerical estimation of the mass concentration of urban aerosol of fractions PM2.5 and PM10. [ABSTRACT FROM AUTHOR]

Many studies are being conducted to determine the optimal cooling arrangement for solar panels. One of the main issues that persists is the cooling effect used to lower the temperature of PV cells. The issue with natural convection air cooling surrounding solar panels is that it is thought to need to be more efficient in absorbing heat. It is necessary to implement effective and efficient cooling techniques. Phase Change Material (PCM) can be used as a cooling agent; the material should be chosen based on its melting point. The choice of a PCM depends on the climate and the material's thermal properties. PCM will absorb more heat throughout the melting process due to its higher latent heat than other materials. Analyzing PCM applications with nano-material addition was investigated numerically with Ansys Fluent. Pure PCM and a combination of nanomaterials were used in the cooling setup. A novel NPCM blend was made using the nanomaterials SiO2 and Al2O3. The mass fraction of the additional nanomaterial is 1%, 5%, and 10%, respectively. Viscous laminar and transient flow conditions were used as methods for this study. The aim of this study is to examine the impact of paraffin-40 combined with nanomaterials on PV cell temperature lowering. PV cell temperature is reduced to 85.98 oC by applying pure paraffin-40 cooling at a heat flux of 1000 W/m². When Al2O3 composition is added at 1%, 5%, and 10%, the PV cell temperature decreases to 59.20, 53.46, and 48.06 OC, respectively. PV cells' temperature with the addition of SiO2 at compositions of 60.95, 59.62, and 57.46 oC, respectively. Blended materials with NPCM work well for solar panel passive cooling. A higher mass concentration of nanomaterials added to the composition has a more significant cooling effect. When added as an extra nanomaterial to PCM, Al2O3 performs better at cooling than SiO2. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The job exposure matrix (JEM) provides annual means of PM10 concentrations for Parisian subway workers. Annual PM10 concentrations are estimated over the period of 2004–2020. What is the implication of the main finding? The JEM approach is relevant to assess occupational long-term exposure to subway PM10. The JEM will allow to examen the health effects of long-term exposure to subway PM10. Introduction: Health effects after long-term exposure to subway particulate matter (PM) remain unknown due to the lack of individual PM exposure data. This study aimed to apply the job exposure matrix (JEM) approach to retrospectively assess occupational exposure to PM in the Parisian subway. Methods: Job, the line and sector of the transport network, as well as calendar period were four JEM dimensions. For each combination of these dimensions, we generated statistical models to estimate the annual average PM10 concentration using data from an exhaustive inventory of the PM measurement campaigns conducted between 2004 and 2020 in the Parisian subway and historical data from the Parisian air pollution monitoring network. The resulting JEM and its exposure estimates were critically examined by experts using the uncertainty analysis framework. Results: The resulting JEM allows for the assignment of the estimated annual PM10 concentration to three types of professionals working in the subway: locomotive operators, station agents, and security guards. The estimates' precision and validity depend on the amount and quality of PM10 measurement data used in the job-, line-, and sector-specific models. Models using large amounts of personal exposure measurement data produced rather robust exposure estimates compared to models with lacunary data (i.e., in security guards). The analysis of uncertainty around the exposure estimates allows for the identification of the sources of uncertainty and parameters to be addressed in the future in order to refine and/or improve the JEM. Conclusions: The JEM approach seems relevant for the retrospective exposure assessment of subway workers. When applied to available data on PM10, it allows for the estimation of this exposure in locomotive operators and station agents with an acceptable validity. Conversely, for security guards, the current estimates have insufficient validity to recommend their use in an epidemiological study. Therefore, the current JEM should be considered as a valid prototype, which shall be further improved using more robust measurements for some jobs. This JEM can also be further refined by considering additional exposure determinants. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advanced Textile Technology is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the atmospheric particulate matter mass concentration of Shandong Qingdao from January 2017 to December 2020， the conventional meteorological observation data and GDAS data， the pollution characteristics of atmospheric particulate matter in this area are studied， and the transmission path of atmospheric particulate matter in Qingdao are analyzed based on HYSPLIT model and TrajStat software.the potential source area and concentration contribution are studied by the Potential Source Contribution Function （PSCF） and Concentration Weighted Trajectory （CWT）.The research findings show： （1） The average annual value of PM2.5 mass concentration in Qingdao was 35.3 µg·m-3.The mass concentration was the highest in winter， followed by spring and autumn， and the lowest in summer.The annual exceeding standard rates of PM2.5 mass concentration were 8.22%， 7.40%， 11.51% and 7.38% respectively.The heavy pollution days only occurred in winter and the pollution days never occurred in summer.（2） The seasonal and diurnal variation of PM2.5 mass concentration presents a "double peak and double Valley" type.The peak value appears at 08:00 （Beijing Time， the same as after） -10:00 and 21:00 -22:00， and the valley value appears at 16:00 -18:00 and 02:00 -04:00.The seasonal diurnal variation of SO2 mass concentration shows a "single peak" type.The daytime concentration is higher than that at night， and the diurnal variation curve fluctuates more obviously in heating season.The diurnal variation of NO2 shows a "double peak and double Valley" type， and the peak time is slightly earlier than that of the diurnal variation of PM2.5.（3） The PM2.5 mass concentration is negatively correlated with air temperature， daily precipitation， wind speed and initial height of inversion， and the correlation coefficients are -0.422， -0.212， -0.106 （wind speed≤2.5 m·s-1） and -0.15 respectively； It is positively correlated with air pressure and inversion intensity， and the correlation coefficients are 0.319 and 0.10 respectively.There is an unobvious correlation between PM2.5 mass concentration and the thickness of atmospheric inversion layer， and the correlation between PM2.5 mass concentration and relative humidity is not unique.（4） The air flow trajectory in spring， autumn and winter comes from the northwest and northerly directions.The northwest air flow accounts for the highest proportion， and they are 70.27%、 75.39% and 100% respectively.The PM2.5 mass concentration in the pollution trajectory is the highest， which is the most important transport path of foreign atmospheric particles in spring， autumn and winter in Qingdao.The southeast air flow trajectory accounts for the largest proportion in summer， accounting for 45.89%.The PM2.5 mass concentration in the pollution track is the highest， which is the main transport path of foreign atmospheric particles in Qingdao in summer.The potential source area of PM2.5 mass concentration has the widest distribution range in winter， the highest WPSCF value， the second in spring and autumn， and the smallest in summer.The main potential pollution source areas and high concentration contribution potential source areas in spring， autumn and winter are located in the south of Hebei， the Middle East of Henan， the west of Anhui， the west of Shanxi and the southwest of Shandong.They are the main source areas for the external transportation of PM2.5 pollution in spring， autumn and winter in Qingdao.The potential source areas of high concentration contribution in summer are located in the southeast of Hebei， the northeast of Henan and the southwest of Shandong and so on.

Low-cost sensors (LCSs) for particulate matter (PM) concentrations have attracted the interest of researchers, supplementing their efforts to quantify PM in higher spatiotemporal resolution. The precision of PM mass concentration measurements from PMS 5003 sensors has been widely documented, though limited information is available regarding their size selectivity and number concentration measurement accuracy. In this work, PMS 5003 sensors, along with a Federal Referral Methods (FRM) sampler (Grimm spectrometer), were deployed across three sites with different atmospheric profiles, an urban (Germanou) and a background (UPat) site in Patras (Greece), and a semi-arid site in Almería (Spain, PSA). The LCSs particle number concentration measurements were investigated for different size bins. Findings for particles with diameter between 0.3 and 10 μm suggest that particle size significantly affected the LCSs' response. The LCSs could accurately detect number concentrations for particles smaller than 1 μm in the urban (R2 = 0.9) and background sites (R2 = 0.92), while a modest correlation was found with the reference instrument in the semi-arid area (R2 = 0.69). However, their performance was rather poor (R2 < 0.31) for coarser aerosol fractions at all sites. Moreover, during periods when coarse particles were dominant, i.e., dust events, PMS 5003 sensors were unable to report accurate number distributions (R2 values < 0.47) and systematically underestimated particle number concentrations. The results indicate that several questions arise concerning the sensors' capabilities to estimate PM2.5 and PM10 concentrations, since their size distribution did not agree with the reference instruments. [ABSTRACT FROM AUTHOR]

Investigating the vertical distribution of mineral dust masses and their microphysical properties is crucial for accurately assessing the climate effects of dust. However, there are limited studies related to relevant in situ observations over dust source areas. In this study, the near-surface vertical characteristics (within 500 m a.g.l) of dust mass concentrations in five size fractions (PMs: TSP, PM10, PM4, PM2.5, and PM1) were investigated using an unmanned aerial vehicle (UAV) in Tazhong (TZ) in the Taklimakan Desert (TD) in July 2021. To the best of our knowledge, the vertical profiles of particle number concentration (PNC), effective radius (Reff), and volume concentration (Cv) were obtained for the first time by UAV over the TD. Four scenarios of clear sky, floating dust, blowing sand, and dust storm were selected based on the classification criteria for PMs. The PMs, PNC, Reff, and Cv decreased with height for all scenarios. From clear-sky to dust-storm scenarios PMs, PNC, Reff, and Cv in the column gradually increased. Reff (Cv) increased from 1.15 μm (0.08 μm3/μm2) to 4.53 μm (0.74 μm3/μm2). The diurnal variations of PMs, PNC, and Reff (Cv) revealed a unimodal pattern, with the peak occurring between 13:00 and 16:00, due to the evolution of wind speed and the atmospheric boundary layer in TZ. Unexpectedly, among the three postprecipitation scenarios (P1, P2, and P3), the PNC of P2 was smaller than those of P1 and P3. The Reff (Cv) for P2 was similar to or greater than that for dust storms, which may be associated with moist dust particles on the ground surface being carried into the air by wind. These investigations add to our understanding of the mineral dust vertical characteristics over the source area, and provide a meaningful reference for colocated lidar inversion and dust simulations. [ABSTRACT FROM AUTHOR]

A new model for the control of financial processes based on metric graphs is presented. Our motivation has its roots in the current interest in finding effective algorithms to detect and classify relations among elements of a social network. For example, the analysis of a set of companies working for a given public administration or other figures in which automatic fraud detection systems are needed. Given a set Ω and a proximity function ϕ : Ω × Ω → ℝ + , we define a new metric for Ω by considering a path distance in Ω that is considered as a graph. We analyze the properties of such a distance, and several procedures for defining the initial proximity matrix (ϕ (a , b)) (a , b) ∈ Ω × Ω . Using this formalism, we state our main idea regarding fraud detection: financial fraud can be detected because it produces a meaningful local change of density in the metric space defined in this way. [ABSTRACT FROM AUTHOR]

A kitchen is an important part of a residence, and air quality in kitchens is a major factor affecting residents' health and performance. Its influence is especially more evident in kitchens with typical Chinese cooking. Thus, it is important to understand distribution characteristics of oil fume particles in Chinese kitchens, and research on typical Chinese kitchen environments and movement characteristics of soot particles should be emphasized. Therefore, to understand the air pollution in kitchen environments, a full-scale experimental platform was built based on common Chinese-style residential kitchens to monitor the soot particles, explore the space–time distribution characteristics of the soot particles, and analyze the variation characteristics and distribution laws of number concentration (NC) and mass concentration (MC). The results indicated that NC0.3μm value fluctuated slightly during the whole cooking process, while NC0.3μm~0.5μm and NC0.5μm~1.0μm fluctuated sharply. During the peak period, NC0.3μm~0.5μm and NC0.5μm~1.0μm were significantly higher than those at the beginning and end of cooking (p < 0.05), and there was no significant difference between values of NC0.3μm~0.5μm and NC0.5μm~1.0μm at the beginning and end of cooking (p > 0.05 for both). NC0.3μm and NC0.3μm~0.5μm were significantly different between each position (p < 0.05 for all). There were also significant differences in NC0.3μm between pure meat dishes, pure vegetable dishes, and mixed dishes (p < 0.001). The proportion of cooking meat will significantly affect the composition and concentration of lampblack particles. Type of dishes is an important influencing factor for the emission rates of particulate pollutants. Small-sized lampblack particles were more likely to diffuse to the surroundings and affected the air quality of the whole room. Particulate matter in the kitchen space during the frying process is more harmful to the health of personnel. [ABSTRACT FROM AUTHOR]

The loading of particulate matter (PM) and levels of particle-bound n-alkanes (C21–C33) in size-segregated aerosols were studied in Delhi on the occasion of Diwali during 3–5 November 2021. Three sets of samples were collected, i.e., Before Diwali (BD), Diwali Day (DD), and After Diwali (AD), in different size ranges. The mass loading was the highest in all size fractions in the DD sample. In the BD sample, the coarse fraction contributed the maximum (49%) to the total mass loading, whereas in DD and AD samples, submicron fractions contributed the most (50% and 46%, respectively). Local meteorology (low temperature, high RH, and low wind speed) played a significant role in the high buildup of pollutants in the atmosphere. Total n-alkanes concentration in the size-segregated PM was several times higher in DD (~ 11–37 times) and AD (~ 9–14 times) samples than in BD samples. Lower n-alkanes (C ≤ 25) with maxima at C25 indicated emissions from increased vehicular activities due to extra movement of people for shopping and meeting friends and relatives during the occasion. The higher n-alkanes (C > 25) with odd–even predominance and maxima at C29 indicated biogenic emissions mainly from candles/oil lamps, wood, and refuse burning during Diwali. CWT analysis of total n-alkanes showed the contribution of local emissions during the Diwali festival. To the best of authors' knowledge, the levels of n-alkanes (C21–C33) in size-segregated PM were studied for the first time during the Diwali festival in Delhi. [ABSTRACT FROM AUTHOR]

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The paper deals with the measurement of individual size components of particulate matter focusing on typical particle size, mass, and number concentrations primarily in the city of Košice (Slovak republic) and the surrounding countryside. The deployment of the sensor IPS-7100 in the 2nd half of December 2022 allowed us to measure the particles smaller than the detection limit of other low-cost optical sensors—namely SPS30 and SEN54. The results show that although the mass concentration of ultrafine particles is negligible in comparison to fine and coarse particles, in terms of number concentration ultrafine particles make up the dominant component of particulate matter, which stands as a warning from the health point of view. [ABSTRACT FROM AUTHOR]