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Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m3/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m3 (for Ba) to 89.62 ng/m3 (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources.

Particulate matter is a serious source of air pollution in urban areas, where it exerts adverse effects on human health. This article focuses on the study of subduction of shelterbelts for atmospheric particulates. The results suggest that (1) the PM mass concentration is higher in the morning or both morning and noon inside the shelterbelts and lower mass concentrations at other times; (2) the particle mass concentration inside shelterbelt is higher than outside; (3) the particle interception efficiency of the two forest belts over the three months in descending order was PM10 > PM1 > PM2.5; and (4) the two shelterbelts captured air pollutants at rates of 1496.285 and 909.075 kg/month and the major atmospheric pollutant in Beijing city is PM10. Future research directions are to study PM mass concentration variation of shelterbelt with different tree species and different configuration.

Background: Moxibustion is a traditional Chinese medicine (TCM) therapy in which mugwort (Artemisia vulgaris) floss is burned to warm and stimulate acupoints. The modality has been used traditionally for thousands of years. However, smoke-related safety issues have recently been of concern, and little is known about moxa smoke and air quality in the clinical moxibustion environment.

This paper is concerned with constraint minimizers of an L2-critical minimization problem (1) in RN (N ≥ 1) under an L2-subcritical perturbation. We prove that the problem admits minimizers with mass ρN/2 if and only 4 if 0 ≤ ρ < ρ* := ‖Q‖24/N for b ≥ 0 and 0 < ρ ≤ ρ* for b < 0, where the constant b comes from the coefficient of the perturbation term, and Q is the unique positive radically symmetric solution of Δu(x) - u(x) + u1+ 4/N (x) = 0 in RN . Furthermore, we analyze rigorously the concentration behavior of minimizers as ρ /' ρ* for the case where b > 0, which shows that the concentration rates are determined by the subcritical perturbation, instead of the local profiles of the potential V (x). [ABSTRACT FROM AUTHOR]

Abstract: This paper summarizes the results of long-term (2004-2016) comprehensive experimental studies of microphysical parameters and the mass concentration of aerosol particles in the atmospheric surface layer of semiarid regions of Kalmykia arranged by the Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences. Characteristic values of the mass and number concentrations of aerosol particles in the summer have been determined for different velocities. A significant decrease in the concentration of surface submicron- and micron-sized aerosols in comparison with their values observed in desert areas of Kalmykia in the 1990s has been found. Mass concentration distributions over aerosol particle fractions have been obtained. The diurnal course of the particle number concentration has been studied taking the meteorological conditions (air temperature, velocity, and humidity) and the underlying surface into consideration. The particle-size distribution functions characteristic of atmospheric aerosols in Kalmykia have been determined. The removal of particles has been coupled with the main meteorological parameters in the atmospheric near-surface layer. A large number of submicron-sized particles have been found to persist in the atmospheric surface layer of semiarid landscapes, confirming that they are the main sources of transport of fine mineral aerosol particles, which are most dangerous to human health and actively engaged in biospheric and climate change processes. [ABSTRACT FROM AUTHOR]

Abstract In this study, Nested Air Quality Prediction Modeling System with Advance Particle Microphysics module (NAQPMS+APM) is applied to simulate the response characteristics of aerosol particle number concentration and mass concentration to emission changes over mainland China. It is the first attempt to investigate the response of both aerosol mass concentration and number concentration to emission changes using a chemical transport model with detailed aerosol microphysics over mainland China. Results indicate that the response characteristics are obviously different between aerosol particle number concentration and mass concentration. Generally, the response of number concentration shows a more heterogeneous spatial distribution than that of mass concentration. Furthermore, number concentration has a higher sensitivity not only to primary particles emission but also to precursor gases than that of mass concentration. Aerosol particle mass concentration exhibits a consistent trend with the emission change and yet aerosol number concentration does not. Due to the nonlinearity of aerosol microphysical processes, reduction of primary particles emission does not necessarily lead to an obvious decrease of aerosol number concentration and it even increases the aerosol number concentration. Over Central-Eastern China (CEC), the most polluted regions in China, reducing primary particles emission rather than precursor gas emissions is more effective in reducing particles number concentration. By contrast, the opposite is true over the northwestern China. The features of fine particles pollution revealed in this study are associated with the spatial differences in China's population, geography, climate and economy. Considering the more adverse effects of ultrafine particles on human health and the spatial distribution of population, making different measures in controlling particles number concentration from that controlling mass concentration in different regions over mainland China is indicated. Main findings FPN concentration responds more heterogeneously to emission than FPM. Spatial difference of response of FPN to emission is distinguished by a boundary line. Graphical abstract Unlabelled Image Highlights • PN concentration responds more heterogeneously to emission change than PM concentration. • Both of primary particles and SO 2 emission reduction can decrease PM concentration. • Reducing primary particles emission is effective in reducing PN concentration over eastern China. • Reducing SO 2 emission is effective in reducing PN concentration over western China. • Spatial difference of response of PN concentration to emission is distinguished by a boundary line. [ABSTRACT FROM AUTHOR]

In order to provide a sound basis for the performance evaluation of a local government's air pollution prevention and abatement measures, the mass concentrations of PM2.5 and PM10 and the concentrations of different sized particles were measured in August 2013. Meanwhile, the influencing factors and sources of atmospheric particulate matters were analyzed by combining meteorological factors and gaseous pollutants. The results indicated that PM2.5 and PM10 in Zhuzhou were (30.3±12.2) μg·m-3 and (56.4±26.6) μg·m-3, respectively. The mean values of the particle number concentration in the size range of 0.5~1 μm and 1~2.5 μm on sunny days were (121.2±75.9) cm-3 and (6.8±3.7) cm-3, respectively, whereas in the rainy days they sharply increased to (868.7±262.1) cm-3 and (347.9±238.6) cm-3, which accounted for 71.0% and 28.4% of the total number of concentrations, respectively. Backward trajectory analysis demonstrated that the air masses in Zhuzhou city mainly came from three directions: southeast (52.2%), southwest (24.7%), and northeast (23.1%). Although accounting for a minor fraction, the northeast air mass had the largest effect on particle concentrations in Zhuzhou and also carried a lot of gaseous primary pollutants. [ABSTRACT FROM AUTHOR]

The accuracy of the particulate matter emission measurement in coal-fired power plants has been enhanced to meet stricter environmental standards. This study discusses the effect of particle size on the in situ concentration measurement of particulate matter by the integrated light scattering method and optimization of the detection angle. The mass concentration sensitivities of five common particles with aerodynamic sizes ranging from 0.05–10 μm have been calculated based on Mie scattering theory at different scattering angles. The scattering light intensity of particles at forward scattering angles has larger magnitudes than that of the back-scattering angles, and the mass sensitivity is remarkably great at small angles. In addition, the fly ash and quartz particles are found to have nearly the same sensitivities at any particle size and scattering angle, and both have maximum values near 1 μm. Then, a real-time aerosol concentration measurement setup was built to study the effect of the particle size and the best detection angle. The results indicate that the optical measurement setup performs in real time and accurately shows good agreement with the calculations. Four quartz particles were represented in the fly ash after the dust collection in power plants was tested and the size factor was found to vibrate with the detection angles. Additionally, 25° is found to be the best detection angle to reduce the size effect. Finally, the optimal detection angle is comprehensively discussed based on the sensitivity, zero drift and size factor, also allowing for the particle density and refractive index. It is found that at angles of ~25°, the size factor and zero drift are lowest, while the sensitivity is relatively high; this outcome helps to reduce the measurement error of the real time-mass concentration of particulates. [ABSTRACT FROM AUTHOR]

Based on the data of PM2.5, PM10, O3, NO2, SO2, and CO hourly concentrations of 121 stations in 22 cities over Sichuan and Chongqing area during 2015-2016, the temporal and spatial distribution characteristics of the air pollutant concentrations and their regional differences were analyzed and discussed. Results indicate that the annual average concentration of particulate matter in most cities of the Sichuan basin is greater than the national standard, mainly centering in Zigong and Chengdu. For O3, the high concentration areas locate in the western and southern basin and Panxi region. The high concentration area of NO2 centers in Chengdu and Chongqing, while the maxima of SO2 and CO concentrations occur in Panzhihua The monthly concentration of O3 is high in summer and low in fall and winter, while the concentrations for the other five pollutants are high in winter and low in summer. The diurnal variations of PM2.5, PM10, NO2, and CO concentrations show the bimodal distribution, characteristics of two concentration peaks appear at night and in the morning with the maxima at night and the minima in the afternoon. The diurnal patterns of O3 and SO2 show the unimodal distribution. Besides, there exist regional and seasonal disparities in the diurnal cycles. For the pollutants with the diurnal pattern of the bimodal distribution, the concentration peak is higher in the morning than at night in the plateau regions, while the situation in the regions of the basin is the opposite. [ABSTRACT FROM AUTHOR]

In a smooth bounded domain Ω of R2 we consider the spectral problem - Ωuε = λ (ε )ρε uε with boundary condition ∂uε/∂ν = 0. The factor ρε plays the role of a mass density, and it is equal to a constant of order ε - 1 in an ε -neighborhood of the boundary and to a constant of order ε-1 in the rest of Ω. We study the asymptotic behavior of the eigenvalues λ(ε) and the eigenfunctions uε as ε tends to zero. We obtain explicit formulas for the first and second terms of the corresponding asymptotic expansions by exploiting the solutions of certain auxiliary boundary value problems. [ABSTRACT FROM AUTHOR]

ABSTRACT Son, M.; Bombardelli, F.A.; Park, B., and Byun, J., 2018. On the Inverse Relationship between Concentration and Size of Cohesive Sediment. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 56–70. Coconut Creek (Florida), ISSN 0749-0208. It is well accepted that the size of floc, the aggregate of cohesive sediment, increases through flocculation processes under high-mass-concentration conditions. However, field studies often show the inverse relationship between floc size and concentration. To examine the mechanism of such inverse relationship, numerical simulations using a robust 1DV model are carried out in this work. At relatively low elevations, the size of floc often has an inverse relationship with concentration under the hydrodynamic conditions of tidal flow and steady current. Nonetheless, the size of floc is proportional to concentration at high elevations. When the inverse relationship exists, the inversion of parameter representing the ratio between aggregation intensity and breakup intensity is found as the hydrodynamics becomes weak. From the findings, it is deduced that the floc size is affected by non-linear interactions between turbulence and concentration. None of them can be used to parameterize the tendency of size variation solely. [ABSTRACT FROM AUTHOR]

The TSI DustTrak monitor has been used for particulate matter (PM) monitoring at various animal facilities. The instrument determines PM concentrations based on the principle of light scattering. Several assumptions (e.g., particle size, refractive index, and density) are imposed during the calibration process; however, they may not apply to PM emanating from agricultural settings. In this study, PM10 monitoring was conducted at a broiler house and a layer breeding house with four collocated instruments: three DustTrak monitors and one tapered element oscillating microbalance (TEOM). Being a federal equivalent method (FEM) for PM10 monitoring, TEOM was selected here as a transfer standard for assessing the field performance of DustTrak. Results revealed a good linearity between DustTrak and TEOM PM10 readings (R2 =0.92 and 0.85 in the broiler and layer breeding houses, respectively). However, DustTrak significantly underestimated PM10 concentrations in both houses. To correct for the monitoring bias by DustTrak, an average correction factor was derived from correlation analysis that characterized the ratio of DustTrak's PM10 response to TEOM's. The factor was calculated as 0.267 for the broiler house and 0.244 for the layer breeding house. Mie scattering simulation was performed to further verify the derived correction factors. A factor of 0.204 was estimated from the simulation, and it accorded well with experimental results. A dependence of the correction factor on PM10 concentration was noted in both poultry houses, indicating the feasibility of developing a concentration-dependent correction factor for future monitoring efforts. Such a relationship could also be explained by Mie scattering. This study is expected to facilitate a better understanding of the limitations and perspectives of the TSI DustTrak and other light scattering PM monitors for agricultural air quality research. [ABSTRACT FROM AUTHOR]

Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226 Ra ( 238 U), 232 Th and 40 K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238 U, 232 Th and 40 K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232 Th/ 238 U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232 Th/ 238 U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection. [ABSTRACT FROM AUTHOR]

Under the condition of ultra-low emission for power plants, the particulate matter concentration is significantly lower than that of typical power plants a decade ago, which posed new challenges for the particulate matter monitoring of stationary emission. The monitoring of particulate matter mass concentration based on ensemble light scattering has been found affected by particle size. Thus, this study develops a method of using the scattering angular distribution to obtain the real-time particle size, and then correct the particulate matter concentration with the real-time measured particle size. In this study, a real-time aerosol concentration and particle size measurement setup is constructed with a fixed detector at the forward direction and a rotating detector. The mass concentration is measured by the fixed detector, and the particle size is measured from the intensity ratio of the two detectors. The simulations show that the particle size has power law functionality with the angular spacing of the ripple structure according to Mie theory. Four quartz aerosols with different particle size are tested during the experiment, and the particle size measured from the ripple width is compared with the mass median size measured by an electrical low pressure impactor (ELPI). Both techniques have the same measurement tendency, and the measurement deviation by the ripple width method compared with ELPI is less than 15%. Finally, the measurement error of the real-time mass concentration is reduced from 38% to 18% with correction of the simultaneously measured particle size when particle size has changed.

Temporal and spatial characteristics of atmospheric particulate matter (PM 10 and PM 2.5 ) and its relationship with meteorology over Shenyang, a city in northeast China, were statistically analyzed using hourly and daily averaged PM mass concentrations measured at 11 locations and surface meteorological parameters, from January 2014 to May 2016. Using averaged data from 11 stations in Shenyang, it was found that the monthly mean PM 2.5 mass concentrations were higher in winter (97.2 ± 11.2 μg m − 3 ) and autumn (85.5 ± 42.9 μg m − 3 ), and lower in spring (62.0 ± 14.0 μg m − 3 ) and summer (42.5 ± 8.4 μg m − 3 ), similar to the seasonal variation in PM 10 concentrations. The monthly ratios of PM 2.5 /PM 10 ranged from 0.41 to 0.87, and were larger in autumn and winter but lowest in spring due to dust activities. PM pollution was concentrated mainly in the central, northern, and western areas of Shenyang in most seasons mainly due to anthropogenic activities such as traffic and residential emission and construction activity as well as natural dust emission. PM concentrations observed over different areas in all seasons generally exhibited two peaks, at 08:00–10:00 local time (LT) and 21:00–23:00 LT, with the exception of PM 2.5 in summer, which showed only one peak during the daytime. In addition, PM 10 concentrations peaked around 14:00 LT during spring in the western area of Shenyang because of strong thermal and dynamic turbulence, resulting in elevated dust emissions from adjacent dust sources. The relationship between daily PM concentrations and meteorological parameters showed both seasonal and annual variation. Overall, both PM 2.5 and PM 10 concentrations were negatively correlated with atmospheric visibility, with correlation coefficients ( R ) of 0.71 and 0.56, respectively. In most seasons, PM concentrations also exhibited negative correlations with wind speed, but showed positive correlations with air pressure, air temperature, and relative humidity. Strong wind speed favored the dispersion of PM pollution, but also aided the release of coarse dust particles in spring. High air pressure and downdrafts restrained the upward movement of atmospheric PM, resulting in an accumulation of particles in the boundary layer. High air temperature favored the transformation of secondary particles through photochemical processes in summer, but also resulted in efficient vertical dispersion of pollutants in autumn and winter, leading to an inverse relationship between temperature and PM concentrations. Large relative humidity usually caused increases in PM concentrations due to the hygroscopic effect of aerosols, but not for PM 10 in spring and summer, mainly due to the suppression of dust emissions under wet air conditions in spring and the effects of wet scavenging under high summer rainfall. [ABSTRACT FROM AUTHOR]

We consider ground states of pseudo-relativistic boson stars with a self-interacting potential K ( x ) in R 3 , which can be described by minimizers of the pseudo-relativistic Hartree energy functional. Under some assumptions on K ( x ) , minimizers exist if the stellar mass N satisfies 0 < N < N ⁎ , and there is no minimizer if N > N ⁎ , where N ⁎ is called the critical stellar mass. In contrast to the case of the Coulomb-type potential where K ( x ) ≡ 1 , we prove that the existence of minimizers may occur at N = N ⁎ , depending on the local profile of K ( x ) near the origin. When there is no minimizer at N = N ⁎ , we also present a detailed analysis of the behavior of minimizers as N approaches N ⁎ from below, for which the stellar mass concentrates at a unique point. [ABSTRACT FROM AUTHOR]

In recent times, there is an intense need for a reliable non‐invasive diabetes prediction system. Some of the researches in this field suggest that acetone gas in breath has a good correlation to blood glucose levels. Hence, acetone is emerging as a promising bio‐marker in diabetes prediction. In this study, acetone levels are measured using quartz crystal microbalance sensor that has wide‐scale application as a bio‐sensor. It is a piezoelectric sensor which is used to detect and quantify mass variations. The resonant frequency of the sensor changes when there is a deposition of mass on the surface of the crystal. The shift in resonant frequency is directly proportional to the change in the mass concentration. To estimate the performance of this sensor, it is required to understand the sensor's electrical characteristics such as its conductance gain and admittance. This study studies these characteristics and evaluates the behaviour of the sensor in the presence of various acetone concentrations in breath sample for healthy, type 1 and type 2 diabetic subjects. [ABSTRACT FROM AUTHOR]

We study minimizers of the pseudo-relativistic Hartree functional $${\mathcal {E}}_{a}(u):=\Vert (-\varDelta +m^{2})^{1/4}u\Vert _{L^{2}}^{2}+\int _{{\mathbb {R}}^{3}}V(x)|u(x)|^{2}\mathrm{d}x-\frac{a}{2}\int _{{\mathbb {R}}^{3}}(\left| \cdot \right| ^{-1}\star |u|^{2})(x)|u(x)|^{2}\mathrm{d}x$$ under the mass constraint $$\int _{{\mathbb {R}}^3}|u(x)|^2\mathrm{d}x=1$$ . Here $$m>0$$ is the mass of particles and $$V\ge 0$$ is an external potential. We prove that minimizers exist if and only if a satisfies $$0\le a0$$ . [ABSTRACT FROM AUTHOR]

Background: Air pollution is a major global environmental risk factor. Since people spend most of their time indoors, the sole measure of outdoor concentrations is not sufficient to assess total exposure to air pollution. Therefore, the arising interest by the international community to indoor-outdoor relationships has led to the development of various techniques for the study of emission and exchange parameters among ambient and non-ambient pollutants. However, a standardised method is still lacking due to the complex release and dispersion of pollutants and the site conditions among studies. Methods: This review attempts to fill this gap to some extent by focusing on the analysis of the variety of site-specific approaches for the assessment of particulate matter in work and life environments. Results: First, the main analogies and differences between indoor and outdoor particles emerging from several studies are briefly described. Commonly-used indicators, sampling methods, and other approaches are compared. Second, recommendations for further studies based on recent results in order to improve the assessment and management of those issues are provided. Conclusions: This review is a step towards a comprehensive understanding of indoor and outdoor exposures which may stimulate the development of innovative tools for further epidemiological and multidisciplinary research. [ABSTRACT FROM AUTHOR]

In this paper, we study the existence and the concentration behavior of critical points for the following functional derived from the Schrödinger–Poisson system: E ( u ) = 1 2 ∫ R 3 | ∇ u | 2 + 1 4 ∫ R 3 ( | x | − 1 ∗ u 2 ) u 2 − 3 10 ∫ R 3 | u | 10 3 constrained on the L 2 -spheres S ( c ) = { u ∈ H 1 ( R 3 ) | | u | 2 = c } when c > c ∗ = | Q | 2 , where Q is up to translations, the unique positive of − Δ Q + 2 3 Q = | Q | 4 3 Q in R 3 . As such constrained problem is L 2 -critical, E ( u ) is unbounded from below on S ( c ) when c > c ∗ and the existence of critical points constrained on S ( c ) is obtained by a mountain pass argument on S ( c ) . We show that there exists c 1 > ( 9 7 ) 3 4 c ∗ such that E ( u ) has at least one positive critical point restricted to S ( c ) for c ∗ < c ≤ c 1 . As c approaches c ∗ from above, we obtain that the critical point u c behaves like ( 1 | ∇ u c | 2 ) 3 2 u c ( 1 | ∇ u c | 2 ( x + y c ) ) ≈ ( 1 c ∗ ) 3 2 Q ( ( 1 c ∗ ) x ) for some y c ∈ R 3 . [ABSTRACT FROM AUTHOR]

Meteorological parameters such as relative humidity have a significant impact on the precision of PM2.5 measurement instruments based on light scattering. Instead of adding meteorological sensors or dehumidification devices used widely in commercial PM2.5 measurement instruments, a novel particle sensor based on multi-angle light scattering and data fusion is proposed to eliminate the effect of meteorological factors. Three photodiodes are employed to collect the scattered light flux at three distinct angles. Weather index is defined as the ratio of scattered light fluxes collected at the 40° and 55° angles, which can be used to distinguish the mass median diameter variation caused by different meteorological parameters. Simulations based on Lorenz-Mie theory and field experiments establish the feasibility of this scheme. Experimental results indicate that mass median diameter has less effect on the photodiode at the 55° angle in comparison with photodiodes at the 40° angle and 140° angle. After correction using the weather index, the photodiode at the 40° angle yielded the best results followed by photodiodes at the 55° angle and the 140° angle. [ABSTRACT FROM AUTHOR]

The TSI DustTrak Aerosol Monitor is a portable real-time instrument widely used for particulate matter (PM) mass concentrations monitoring. The aim of this work is to report on issues that have arisen from the use of the latest generation models DustTrak DRX (8533 and 8534) in the BREATHE, UPTECH and IMPROVE projects that can compromise data quality. The main issue we encountered was the occurrence of sudden artefact jumps in PM concentration, which can involve an increase from a few to some hundreds of μg·m − 3 . These artefact jumps can sometimes be easily recognised (“obvious jump”), while others can be difficult to identify because the difference in the concentrations before and after the jump might be just few μg·m − 3 (“possible jump”) or because the jump is sustained over the whole monitoring period and only detectable if PM concentrations are simultaneously measured by other instruments (“hidden jump”). Moreover, in areas of relatively low PM levels, the unit reported concentration of 0 μg·m − 3 for ambient PM concentration or even negative concentration values which may seriously compromise the dataset. These data suggest issues with the detection of low PM concentrations, which could be due to an incorrect instrument offset or the factory calibration setting being inadequate for these PM concentrations. The upward and downward artefact jumps were not related to especially dusty or clean conditions, since they have been observed in many kinds of environments: indoor and outdoor school environments, subway stations and in ambient urban background air. Therefore, PM concentration data obtained with the TSI DustTrak DRX models should be handled with care and meticulously revised before being considered valid. To prevent these issues the use of auto zero module is recommended, so the DustTrak monitor is automatic re-zeroed without requiring the presence of any user. [ABSTRACT FROM AUTHOR]

An Aerodyne quadrupole aerosol mass spectrometry (Q-AMS) was utilized to measure the size-resolved chemical composition of non-refractory submicron particles (NR-PM 1 ) from October 27 to December 3, 2014 at an urban site in Lanzhou, northwest China. The average NR-PM 1 mass concentration was 37.3 μg m −3 (ranging from 2.9 to 128.2 μg m −3 ) under an AMS collection efficiency of unity and was composed of organics (48.4%), sulfate (17.8%), nitrate (14.6%), ammonium (13.7%), and chloride (5.7%). Positive matrix factorization (PMF) with the multi-linear engine (ME-2) solver identified six organic aerosol (OA) factors, including hydrocarbon-like OA (HOA), coal combustion OA (CCOA), cooking-related OA (COA), biomass burning OA (BBOA) and two oxygenated OA (OOA1 and OOA2), which accounted for 8.5%, 20.2%, 18.6%, 12.4%, 17.8% and 22.5% of the total organics mass on average, respectively. Primary emissions were the major sources of fine particulate matter (PM) and played an important role in causing high chemically resolved PM pollution during wintertime in Lanzhou. Back trajectory analysis indicated that the long-range regional transport air mass from the westerly was the key factor that led to severe submicron aerosol pollution during wintertime in Lanzhou. [ABSTRACT FROM AUTHOR]

Air quality has increasingly been a great concern all over the world, and the good command of indoor and outdoor air qualities is of benefit to the air pollution alleviation by various measures. In this work, the indoor and outdoor particle concentration distributions of a typical meeting room during the haze and clear-sky days were measured. The results show that the mass concentrations of the indoor and outdoor PM, PM, PM10 in heavy haze days are 114±1.8, 135.5±3.2, 161.7±12.8 μg/m and 146.4±8.4, 192.3±10.2, 431.4±34.8 μg/m respectively, corresponding to 39.3±1.5, 58.5±2.5, 127.9±10.5 μg/m and 54.5±4.0, 77.8±6.0, 173.4±21.6 μg/m in clear-sky days. Both in the haze and clear-sky days, the number distribution of particles reaches its peak value at the diameter of 0.25 μm, but the particle number concentration in the haze day is two times greater than the clear-sky day. The indoor particle concentration is not uniform with the peak value at the corner, which can be effectively alleviated by the air cleaner. The in-situ measurements of particle concentrations in a meeting room are helpful for the indoor air quality control. [ABSTRACT FROM AUTHOR]

In this paper we consider a two-dimensional attractive Bose–Einstein condensate with periodic potential, described by Gross–Pitaevskii (GP) functional. By concentration-compactness lemma we show that minimizers of this functional exist when the interaction strength a satisfies a ⁎ < a < a ⁎ for some constants a ⁎ ≥ 0 , a ⁎ > 0 , and there is no minimizer for a ≥ a ⁎ . When a approaches a ⁎ , using concentration-compactness arguments again we obtain an optimal energy estimate depending on the shape of periodic potential. Moreover, we analyze the mass concentration. [ABSTRACT FROM AUTHOR]

This paper considers ground states of mass subcritical rotational nonlinear Schrödinger equation − Δ u + V (x) u + i Ω (x ⊥ ⋅ ∇ u) = μ u + ρ p − 1 | u | p − 1 u in R 2 , where V (x) is an external potential, Ω > 0 characterizes the rotational velocity of the trap V (x) , 1 < p < 3 , and ρ > 0 describes the strength of the attractive interactions. It is shown that ground states of the above equation can be described equivalently by minimizers of the L 2 -constrained variational problem. We prove that minimizers exist for any ρ ∈ (0 , ∞) when 0 < Ω < Ω ∗ , where 0 < Ω ∗ ≔ Ω ∗ (V) < ∞ denotes the critical rotational velocity. While Ω > Ω ∗ , there admits no minimizers for any ρ ∈ (0 , ∞). For fixed 0 < Ω < Ω ∗ , by using energy estimates and blow-up analysis, we also analyze the mass concentration behavior of minimizers as ρ → ∞. Finally, we prove that up to a constant phase, there exists a unique minimizer when Ω ∈ (0 , Ω ∗) is fixed and ρ > 0 is large enough. [ABSTRACT FROM AUTHOR]

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 PM 10 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 PM 10 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 PM 10 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 PM 10 , 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.

The classes and concentrations of volatile organic compounds (VOC) released from fresh and decaying strawberries were investigated and compared. In this study, a total of 147 strawberry volatiles were quantified before and after nine days of storage to explore differences in the aroma profile between fresh strawberries (storage days (SRD) of 0, 1, and 3) and those that had started to decay (SRD = 6 and 9). In terms of concentration, seven compounds dominated the aroma profile of fresh strawberries (relative composition (RC) up to 97.4% by mass, sum concentration): (1) ethyl acetate = 518 mg∙m−3, (2) methyl acetate = 239 mg∙m−3, (3) ethyl butyrate = 13.5 mg∙m−3, (4) methyl butyrate = 11.1 mg∙m−3, (5) acetaldehyde = 24.9 mg∙m−3, (6) acetic acid = 15.2 mg∙m−3, and (7) acetone = 13.9 mg∙m−3. In contrast, two alcohols dominated the aroma profile of decayed samples (RC up to 98.6%): (1) ethyl alcohol = 94.2 mg∙m−3 and (2) isobutyl alcohol = 289 mg∙m−3. Alternatively; if the aroma profiles are re-evaluated by summing odor activity values (ΣOAV); four ester compounds ((1) ethyl butyrate (6,160); (2) ethyl hexanoate (3,608); (3) ethyl isovalerate (1,592); and (4) ethyl 2-methylbutyrate (942)) were identified as the key constituents of fresh strawberry aroma (SRD-0). As the strawberries began to decay; isobutyl alcohol recorded the maximum OAV of 114 (relative proportion (RP) (SRD = 6) = 58.3%). However, as the decay process continued, the total OAV dropped further by 3 to 4 orders of magnitude—decreasing to 196 on SRD = 6 to 7.37 on SRD = 9. The overall results of this study confirm dramatic changes in the aroma profile of strawberries over time, especially with the onset of decay.

Background and Aims : Many systems and processes can cause the introduction of radioactivity into the environment. Human activities in nuclear industry such as nuclear fuel cycle and reactor operation, lead to a significant production and release of radioactivity to the environment. Understanding the physical and chemical nature, including size, chemical composition and radioactivity of aerosol particles in the safety chamber of Tehran research reactor is indispensable for evaluation of exposure level and methods of prevention. The aim of this study was to measure the size distribution of aerosols and their activities, which was determined using an Anderson cascade Impactor (ACI) ACFM model and liquid scintillation respectively. The measurements were performed in three workstations in the safety chamber of Tehran research reactor. Methods: The identification of existing radio nuclides on suspended particles were carried out in the safety chamber by means of environmental sampler and mass size distribution of particles was measured using an Anderson cascade Impactor (ACI). To determine the type and amount of radio nuclides in the aerosol particles the γ-ray spectrometry with a high –purity germanium (HPGe) detector and ultra-low level liquid scintillation spectrometer were used respectively. Results : The results showed that the activities median aerodynamic diameter (AMAD) value for three selected workstations were 2.4, 3.1 and 3µm with geometric standard deviation of 2.3, 2.12 and 2 respectively. Furthermore, the results of particle activity size distribution showed that the most fraction of activity was related to nucleation and accumulation mode, especially particles with the aerodynamic diameter less than 0.4µm. Conclusion: The most activity was related to the number of particles in the accumulation and nucleation mode (fine particles). The origin of these particles can be the coagulation of particles in the nucleation mode. The accumulation mode also contains droplets formed by the chemical conversion of gases to vapors that condense.