The frequent transport of Sahara dust toward Europe degrades the air quality and poses risk to human health. In this study we use GEOS-Chem (a global transport model) to examine the impact of Sahara ...dust on air quality and the consequent health effect in Europe (10°W – 20°E, 35°N – 60°N) for the year 2016–2017. The model performance is evaluated by comparisons with surface observations including aerosol optical depth (AOD) from AERONET, and PM2.5 and PM10 concentrations from numerous monitoring stations. The spatial distribution of dust concentrations, frequency of dust episodes, as well as the exposure and health effects are studied. The concentrations of Sahara dust decrease from 5–20 μg m−3 in south to 0.5–1.0 μg m−3 in north of Europe. Spain and Italy are most heavily influenced by Sahara dust in terms of both concentration levels and frequencies of occurrence. Strong dust episodes (>50 μg m−3) occur predominately in Southern Spain and Italy with frequency of 2–5%, while light dust episodes (>1 μg m−3) are often detected (5–30%) in Central and Western Europe. The population-weighted dust concentrations are higher in Southern European countries (3.3–7.9 μg m−3) and lower in Western European countries (0.5–0.6 μg m−3). We estimate a total of 41884 (95% CI: 2110–81658) deaths per year attributed to the exposure to dust in the 13 European countries studied. Due to high contribution to PM10 in Spain, Italy and Portugal, dust accounts for 44%, 27% and 22% of the total number of deaths linked to PM10 exposure, respectively.
•Transport of Sahara dust to Europe is successfully modelled using GEOS-Chem.•Dust levels are high in Spain and Italy, and decrease from south to north of Europe.•Light dust events (>1 μg m−3) occur 5–30% in Western and Central Europe.•41884 (CI95: 2110–81658) deaths per year attributed to dust in 13 European countries.•Dust accounts for 27–44% of the N. of deaths related to PM10 in Italy and Spain.
A novel heterogeneous manganese/graphitic carbon nitride (Mn3O4-CN) catalyst for activating peroxymonosulfate (PMS) was successfully assembled using alkali precipitation. The g-C3N4 improved the ...composite’s surface morphology, micro-porous structure, surface area, and particle size distribution, and an electron-rich center with Mn site was created. The Mn3O4-CN/PMS system exhibited high efficiency and stability when the solution pH varied from 3.0 to 9.0, with more than 90% of p-acetaminophen (ACT) removal in 30 min under experimental conditions. A possible reaction mechanism was proposed, primarily involving electron transfer from Mn (II) and Mn (III) to PMS along with the generation of·O2- and 1O2, and the degradation of ACT was attributed to the 1O2. Specifically, the degradation rate of phenolic compounds varied with their molecular structure in the following order: ACT > bisphenol A (BPA) > p-cresol (MP) > p-chlorophenol (CP) > phenol (Ph) > p-nitrophenol (NP). Further, the density functional theory (DFT) calculations indicated that the phenols’ degradation efficiency was related to their adsorption energy and Bader charge value. These results improved our understanding of the manganese-based PMS non-radical dominated process and provided a method for predicting the degradation performance of phenols for the first time.
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•Mn3O4-CN exhibited promoting effect on ACT degradation in the PMS activation system.•The PMS activation coordinated with the Mn valence change.•Electron transfer between ACT and high valence Mn renewed the catalyst surface.•ACT degradation was primarily attributed to 1O2.•The structure-dependence degradation of phenols in the PMS system was confirmed.
Previous studies have demonstrated some associations between dietary vitamin A intake and ovarian cancer risk with an inconsistent relationship. We therefore performed the present study to further ...explore the association between them.
Databases of PubMed, Embase, and Web of Science were retrieved up to September 1, 2019. Summarized relative risk (RR) with corresponding 95% confidence intervals (CI) were calculated. Stata 14.0 software was used for data analysis.
Fifteen articles involving 4882 cases and 443,179 participants were included in this meta-analysis. A positive association between dietary vitamin A intake and ovarian cancer risk was found (RR = 0.816, 95%CI = 0.723-0.920, I2 = 48.4%, Pfor heterogeneity = 0.019). Significant association was also found in case-control studies (RR = 0.769, 95%CI = 0.655-0.902), but not in cohort studies. When we performed the analysis between ovarian cancer risk and geographic locations, we found an inverse association in North American populations (RR = 0.825, 95%CI = 0.720-0.946), instead of other populations.
In summary, findings from the present study suggested that higher dietary intake of vitamin A may contribute to the lower development of ovarian cancer, especially among North Americans.
Near infrared (NIR)-emitting persistent luminescent nanoparticles have been developed as potential agents for bioimaging. However, synthesizing uniform nanoparticles with long afterglow for long-term ...imaging is lacking. Here, we demonstrated the synthesis of spinel structured Zn
3
Ga
2
Ge
2
O
10
:Cr
3+
(ZGGO:Cr
3+
) and Zn
3
Ga
2
Ge
2
O
10
:Cr
3+
,Eu
3+
(ZGGO:Cr
3+
,Eu
3+
) nanoparticles by a sol-gel method in combination with a subsequent reducing atmosphere-free calcination. The samples were investigated via detailed characterizations by combined techniques of XRD, TEM, STEM, selected area electron diffraction, photoluminescence excitation (PLE)/photoluminescence (PL) spectroscopy, and temperature-dependent PL analysis. The single-crystalline nanoparticles are homogeneous solid solution, possessing uniform cubic shape and lateral size of ~ 80–100 nm. Upon UV excitation at 273 nm, ZGGO:Cr
3+
,Eu
3+
exhibited a NIR emission band at 697 nm (
2
E →
4
A
2
transition of distorted Cr
3+
ions in gallogermanate), in the absence of Eu
3+
emission. NIR persistent luminescence of the sample can last longer than 7200 s and still hold intense intensity. Eu
3+
incorporation increased the persistent luminescence intensity and the afterglow time of ZGGO:Cr
3+
, but it did not significantly affect the thermal stability. The obtained ZGGO:Cr
3+
,Eu
3+
-NH
2
nanoparticles possessed an excellent imaging capacity for cells in vitro.
We use a global chemical transport model (GEOS‐Chem) to interpret aircraft curtain observations of black carbon (BC) aerosol over the Pacific from 85°N to 67°S during the 2009–2011 HIAPER ...(High‐Performance Instrumented Airborne Platform for Environmental Research) Pole‐to‐Pole Observations (HIPPO) campaigns. Observed concentrations are very low, implying much more efficient scavenging than is usually implemented in models. Our simulation with a global source of 6.5 Tg a−1 and mean tropospheric lifetime of 4.2 days (versus 6.8 ± 1.8 days for the Aerosol Comparisons between Observations and Models (AeroCom) models) successfully simulates BC concentrations in source regions and continental outflow and captures the principal features of the HIPPO data but is still higher by a factor of 2 (1.48 for column loads) over the Pacific. It underestimates BC absorbing aerosol optical depths (AAODs) from the Aerosol Robotic Network by 32% on a global basis. Only 8.7% of global BC loading in GEOS‐Chem is above 5 km, versus 21 ± 11% for the AeroCom models, with important implications for radiative forcing estimates. Our simulation yields a global BC burden of 77 Gg, a global mean BC AAOD of 0.0017, and a top‐of‐atmosphere direct radiative forcing (TOA DRF) of 0.19 W m−2, with a range of 0.17–0.31 W m−2 based on uncertainties in the BC atmospheric distribution. Our TOA DRF is lower than previous estimates (0.27 ± 0.06 W m−2 in AeroCom, 0.65–0.9 W m−2 in more recent studies). We argue that these previous estimates are biased high because of excessive BC concentrations over the oceans and in the free troposphere.
Key Points
A global distribution of BC is simulated in GEOS‐Chem
Results imply more efficient BC removal than is usually included in models
Previous estimates of DRF from BC were biased high due to excessive remote BC
Wildfires inject large amounts of black carbon (BC) particles into the atmosphere, which can reach the lowermost stratosphere (LMS) and cause strong radiative forcing. During a 14-month period of ...observations on board a passenger aircraft flying between Europe and North America, we found frequent and widespread biomass burning (BB) plumes, influencing 16 of 160 flight hours in the LMS. The average BC mass concentrations in these plumes (∼140 ng·m−3, standard temperature and pressure) were over 20 times higher than the background concentration (∼6 ng·m−3) with more than 100-fold enhanced peak values (up to ∼720 ng·m−3). In the LMS, nearly all BC particles were covered with a thick coating. The average mass equivalent diameter of the BC particle cores was ∼120 nm with a mean coating thickness of ∼150 nm in the BB plume and ∼90 nm with a coating of ∼125 nm in the background. In a BB plume that was encountered twice, we also found a high diameter growth rate of ∼1 nm·h−1 due to the BC particle coatings. The observed high concentrations and thick coatings of BC particles demonstrate that wildfires can induce strong local heating in the LMS and may have a significant influence on the regional radiative forcing of climate.
Black carbon (BC) plays an important role in the climate system because of its strong warming effect, yet the magnitude of this effect is highly uncertain owing to the complex mixing state of ...aerosols. Here we build a unified theoretical framework to describe BC's mixing states, linking dynamic processes to BC coating thickness distribution, and show its self-similarity for sites in diverse environments. The size distribution of BC-containing particles is found to follow a universal law and is independent of BC core size. A new mixing state module is established based on this finding and successfully applied in global and regional models, which increases the accuracy of aerosol climate effect estimations. Our theoretical framework links observations with model simulations in both mixing state description and light absorption quantification.
Autonomous vehicles (AVs) are supposed to make appropriate strategies to ensure driving safety and improve traffic efficiency. However, not all collisions will be avoidable. In a typical dilemma ...scenario of this paper, we have to make hard decisions from two evils, sparing a child with red-light running behavior or crashing into a well-equipped motorcycle driver without violation of the traffic law. Combined with the existing traffic laws and the accident liability judgment cases in China, 12 typical dilemma scenarios are established. In order to acquire data to analyze the driving decision-making factors involving ethics and legal under the moral dilemma of AVs, we conduct a series of experiments in virtual reality environments. Furthermore, key factors are extracted to characterize the driving decisions under different scenarios and quantified by the gray relation entropy analysis method. Particularly, the ethical factor is represented by the quantity and type of collision targets, the legal factor is qualified by rights of way. The results showed that priority levels of the influencing factors in each moral dilemma were considerably different. Nevertheless, when the quantity of collision targets on two sides is equal, more participants prefer to protect the ones that comply with traffic rules. The research results can provide the basis for designing moral algorithms for the AVs.
Molecular visualization is often challenged with rendering of large molecular structures in real time. The key to LOD (level-of-detail), a classical technology, lies in designing a series of ...hierarchical abstractions of protein. In the paper, we improved the smoothness of transition for these abstractions by constructing a complete binary tree of a protein. In order to reduce the degree of expansion of the geometric model corresponding to the high level of abstraction, we introduced minimum ellipsoidal enveloping and some post-processing techniques. At the same time, a simple, ellipsoid drawing method based on graphics processing unit (GPU) is used that can guarantee that the drawing speed is not lower than the existing sphere-drawing method. Finally, we evaluated the rendering performance and effect on series of molecules with different scales. The post-processing techniques applied, diffuse shading and contours, further conceal the expansion problem and highlight the surface details.
Brown carbon (BrC) is a type of organic carbon with light-absorbing abilities, especially in ultraviolet (UV) radiation, which could significantly contribute to global warming. Observations have ...shown high BrC concentrations and absorption in China, suggesting potentially large BrC emissions. The potential contribution of fossil fuel combustion to BrC emission has been ignored in most previous studies. Here, we use GEOS-Chem to simulate BrC distribution and absorption in China, accounting for three major primary BrC sources: residential coal and biofuel combustion, vehicle exhausts, and open biomass burning. Based on the literature and related energy consumption data, we estimate the specific emission ratio of BrC versus BC, and BrC mass absorption efficiency (MAE) for each source. Combined with BC emission, total BrC emission in China is then estimated to be 3.42 Tg yr−1 in 2018, of which 71% is from residential combustion, 14% is from vehicle exhaust, and 15% is from open biomass burning. Residential combustion is the main source of surface BrC in China, accounting for 60% on average, followed by open biomass burning (23%) and vehicle exhaust emissions (17%). There is a clear seasonality in surface BrC concentrations with the maximum in winter (5.1 µg m−3), followed by spring (2.8 µg m−3), autumn (2.3 µg m−3), and summer (1.3 µg m−3). BrC AAOD at 365 nm ranges from 0.0017 to 0.060 in China, mainly dominated by residential combustion (73%), followed by open biomass burning (16%), and vehicle exhaust emissions (11%). It is also estimated that BrC accounts for 45–67% (52% on average) of total carbonaceous aerosol AAOD at 365 nm, implying an equal importance of BrC and BC regarding the absorption in UV radiation.
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