| 31. |
- Cai, Jing, et al.
(författare)
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Size-segregated particle number and mass concentrations from different emission sources in urban Beijing
- 2020
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 20:21, s. 12721-12740
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Tidskriftsartikel (refereegranskat)abstract
- Although secondary particulate matter is reported to be the main contributor of PM2.5 during haze in Chinese megacities, primary particle emissions also affect particle concentrations. In order to improve estimates of the contribution of primary sources to the particle number and mass concentrations, we performed source apportionment analyses using both chemical fingerprints and particle size distributions measured at the same site in urban Beijing from April to July 2018. Both methods resolved factors related to primary emissions, including vehicular emissions and cooking emissions, which together make up 76% and 24% of total particle number and organic aerosol (OA) mass, respectively. Similar source types, including particles related to vehicular emissions (1.6 +/- 1.1 mu gm(-3); 2.4 +/- 1.8 x 10(3) cm(-3) and 5.5 +/- 2.8 x 10(3) cm(-3) for two traffic-related components), cooking emissions (2.6 +/- 1.9 mu gm(-3) and 5.5 +/- 3.3 x 10(3) cm(-3)) and secondary aerosols (51 +/- 41 mu gm(-3) and 4.2 +/- 3.0 x 10(3) cm(-3)), were resolved by both methods. Converted mass concentrations from particle size distributions components were comparable with those from chemical fingerprints. Size distribution source apportionment separated vehicular emissions into a component with a mode diameter of 20 nm (traffic-ultrafine) and a component with a mode diameter of 100 nm (traffic-fine). Consistent with similar day- and nighttime diesel vehicle PM2.5 emissions estimated for the Beijing area, traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor resulting from source apportionment using chemical fingerprints) and black carbon (BC) showed similar diurnal patterns, with higher concentrations during the night and morning than during the afternoon when the boundary layer is higher. Traffic-ultrafine particles showed the highest concentrations during the rush-hour period, suggesting a prominent role of local gasoline vehicle emissions. In the absence of new particle formation, our re-sults show that vehicular-related emissions (14% and 30% for ultrafine and fine particles, respectively) and cooking-activity-related emissions (32 %) dominate the particle number concentration, while secondary particulate matter (over 80 %) governs PM2.5 mass during the non-heating season in Beijing.
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| 32. |
- Cao, Lin-Ying, et al.
(författare)
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Structure-dependent activity of polybrominated diphenyl ethers and their hydroxylated metabolites on estrogen related receptor gamma : in vitro and in silico study
- 2018
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:15, s. 8894-8902
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen-related receptor gamma (ERR gamma) is an orphan nuclear receptor having functional cross-talk with classical estrogen receptors. Here, we investigated whether ERR gamma is a potential target 8 of polybrominated diphenyl ethers (PBDEs) and their hydroxylated metabolites (OH-PBDEs). By using a fluorescence competitive binding method established in our laboratory, the binding potencies of 30 PBDEs/OH-PBDEs with ERR gamma were determined for the first time. All of the tested OH-PBDEs and some PBDEs bound to ERR gamma with K-d values ranging from 0.13-13.61 mu M. The OH-PBDEs showed much higher binding potency than their parent PBDEs. A quantitative structure-activity relationship (QSAR) model was developed to analyze the chemical binding potencies in relation to their structural and chemical characteristics. The QSAR model indicated that the molecular size, relative ratios of aromatic atoms, and hydrogen bond donors and acceptors were crucial factors for PBDEs/OH-PBDEs binding. By using a reporter gene assay, we found that most of the low-brominated PBDEs/OH-PBDEs exerted agonistic activity toward ERR gamma, while high-brominated PBDEs/OH-PBDEs had no effect on the basal ERR gamma activity. The docking results showed that the low-brominated PBDEs/OH-PBDEs tended to take an agonistic binding mode while the high-brominated ones tended to take an antagonistic binding mode. Overall, our results suggest ERR gamma to be a potential novel target for PBDEs/OH-PBDEs.
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| 33. |
- Cao, Yuehan, et al.
(författare)
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Modulating electron density of vacancy site by single Au atom for effective CO2 photoreduction
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The surface electron density significantly affects the photocatalytic efficiency, especially the photocatalytic CO2 reduction reaction, which involves multi-electron participation in the conversion process. Herein, we propose a conceptually different mechanism for surface electron density modulation based on the model of Au anchored CdS. We firstly manipulate the direction of electron transfer by regulating the vacancy types of CdS. When electrons accumulate on vacancies instead of single Au atoms, the adsorption types of CO2 change from physical adsorption to chemical adsorption. More importantly, the surface electron density is manipulated by controlling the size of Au nanostructures. When Au nanoclusters downsize to single Au atoms, the strong hybridization of Au 5d and S 2p orbits accelerates the photo-electrons transfer onto the surface, resulting in more electrons available for CO2 reduction. As a result, the product generation rate of AuSA/Cd1−xS manifests a remarkable at least 113-fold enhancement compared with pristine Cd1−xS.
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| 34. |
- Dan, Meng, et al.
(författare)
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A dual-interfacial system with well-defined spatially separated redox-sites for boosting photocatalytic overall H2S splitting
- 2021
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 423
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Tidskriftsartikel (refereegranskat)abstract
- Integration of high activity, selectivity, and stability is urgently desired to achieve more ideal photocatalysts. Herein, we reported the rational design of MoS2-MnS@(InxCu1-x)2S3 (M-M@IC) catalysts with dual interface to integrate separated redox sites for boosting photocatalytic hydrogen sulphide (H2S) splitting and the resource utilization of sacrificial reagents (Na2S/Na2SO3). The spatially separated reduction (MnS) and oxidation (In2S3) sites in MnS/In2S3 heterojunction, on which MoS2 and Cu were selectively loaded, can drive electrons and holes near the surface to flow along opposite directions, while the heterojunction between MnS and In2S3 inhibits the bulk charge recombination. Furthermore, the introduction of Cu atoms creates a d-band center, which favours mass diffusion of reactants/products species and greatly facilitates sunlight response. The MoS2 serves to provide abundant sites for proton reduction due to the unsaturated-sulfur-edge-rich (US-rich) nature. As a result, the M−M@IC shows a state-of-the-art visible-light photocatalytic H2 evolution rate (126.5 mmol g-1h−1), inspiring stability of >50 h, and nearly 100% selectivity toward value-added Na2S2O3 production under optimized condition. This work opens up new opportunities for the construction and design of spatially separated catalytic site in photocatalysts.
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| 35. |
- Dan, Meng, et al.
(författare)
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Beyond hydrogen production : Solar−driven H2S−donating value−added chemical production over MnxCd1−xS/CdyMn1−yS catalyst
- 2021
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373. ; 284
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous hydrogen (H2) evolution and value−added chemicals production are highly attractive but have not drawn enough attention. Here, we demonstrate a hydrogen sulphide (H2S)−induced product−targeting (HIPT) strategy for the coproduction of H2 and valuable chemical feedstocks from Na2S/Na2SO3 via overall H2S splitting using a MnxCd1−xS/CdyMn1−yS catalyst driven by visible light excitation. With this chemistry, 113 mmol g−1 h−1 of hydrogen evolution rate is achieved, surpassing most of the previously reported state-of-the-art photocatalyst, together with the production of value−added Na2S2O3 with nearly 100% selectivity. This work not only provides a good example for solar energy conversion via overall H2S splitting, but also offers new insights into the resource utilization of sacrificial donor (Na2S/Na2SO3) in various catalytic fields such as H2O splitting and CO2 reduction.
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| 36. |
- de Vries, Paul S., et al.
(författare)
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Multiancestry Genome-Wide Association Study of Lipid Levels Incorporating Gene-Alcohol Interactions
- 2019
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Ingår i: American Journal of Epidemiology. - : Oxford University Press. - 0002-9262 .- 1476-6256. ; 188:6, s. 1033-1054
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Tidskriftsartikel (refereegranskat)abstract
- A person's lipid profile is influenced by genetic variants and alcohol consumption, but the contribution of interactions between these exposures has not been studied. We therefore incorporated gene-alcohol interactions into a multiancestry genome-wide association study of levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides. We included 45 studies in stage 1 (genome-wide discovery) and 66 studies in stage 2 (focused follow-up), for a total of 394,584 individuals from 5 ancestry groups. Analyses covered the period July 2014-November 2017. Genetic main effects and interaction effects were jointly assessed by means of a 2-degrees-of-freedom (df) test, and a 1-df test was used to assess the interaction effects alone. Variants at 495 loci were at least suggestively associated (P < 1 x 10(-6)) with lipid levels in stage 1 and were evaluated in stage 2, followed by combined analyses of stage 1 and stage 2. In the combined analysis of stages 1 and 2, a total of 147 independent loci were associated with lipid levels at P < 5 x 10(-8) using 2-df tests, of which 18 were novel. No genome-wide-significant associations were found testing the interaction effect alone. The novel loci included several genes (proprotein convertase subtilisin/kexin type 5 (PCSK5), vascular endothelial growth factor B (VEGFB), and apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 (APOBEC1) complementation factor (A1CF)) that have a putative role in lipid metabolism on the basis of existing evidence from cellular and experimental models.
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| 37. |
- Duan, Zheng, et al.
(författare)
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Aquatic environment monitoring using a drone-based fluorosensor
- 2019
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Ingår i: Applied Physics B: Lasers and Optics. - : Springer Science and Business Media LLC. - 0946-2171. ; 125
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Tidskriftsartikel (refereegranskat)abstract
- A drone-based system for monitoring of laser-induced fluorescence from the aquatic environment was constructed. Fixed-range remote-sensing demonstration measurements were performed, and field recordings of natural river water fluorescence, oil-slicks as well as dye-marked natural water volumes were taken at drone flying heights of about 10 m. Our fluorosensor, weighing only 1.5 kg, and carried by a commercial drone, illustrates how airborne remote sensing based on fluorescence can be made cost-effective and readily applicable, while presently only in ambient low-light-level conditions.
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| 38. |
- Duan, Zheng, et al.
(författare)
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Remote LIBS Measurements on Metals Using a Mobile Lidar System
- 2018
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Ingår i: 2018 Asia Communications and Photonics Conference, ACP 2018. - 9781538661581 ; 2018-October
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Konferensbidrag (refereegranskat)abstract
- The preliminary remote laser-induced breakdown spectroscopy measurement of metals is performed on a mobile lidar system. The Nd:YAG laser synchronized with an ICCD spectrometer, the detection range can be achieved up to 45 m.
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| 39. |
- El-Serafi, Ahmed, 1977-, et al.
(författare)
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Vitamin D levels and busulphan kinetics in patients undergoing hematopoietic stem cell transplantation, a multicenter study
- 2021
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Ingår i: Bone Marrow Transplantation. - : SPRINGERNATURE. - 0268-3369 .- 1476-5365. ; 56, s. 807-817
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Tidskriftsartikel (refereegranskat)abstract
- Vitamin D (Vit-D), an essential nutrient, interacts with different drugs including chemotherapeutic agents like busulphan, an alkylating agent used for conditioning prior to stem cell transplantation. The correlation between Vit-D plasma levels and busulphan clearance was investigated in an uncontrolled prospective study in patients and mice. Plasma 25(OH)D levels were measured and busulphan pharmacokinetics calculated in 81 patients. Adults received oral busulphan (n = 34) while children received busulphan orally (n = 19) or intravenously (n = 28). Patients received no Vit-D supplementation. To confirm our findings, pharmacokinetics after a single dose of busulphan (oral or intravenous) were evaluated in two groups of mice (n = 60) receiving high or standard-level Vit-D supplementation. Both busulphan clearance (P < 0.0001) and 25(OH)D levels (P = 0.0004) were significantly higher in adults compared to children. A significant negative correlation (P = 0.041) was found between busulphan clearance and 25(OH)D levels in children treated orally. No such correlation was observed in adults or in children receiving intravenous busulphan. In addition, no significant effect of Vit-D levels on busulphan pharmacokinetics in mice regardless of the administration route. In conclusion, 25(OH)D can affect oral busulphan pharmacokinetics in children and its level should be considered when personalizing oral busulphan treatment. Further studies are warranted to confirm the underlying mechanisms.
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| 40. |
- Fan, Zheyong, et al.
(författare)
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GPUMD: A package for constructing accurate machine-learned potentials and performing highly efficient atomistic simulations
- 2022
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 157:11
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Tidskriftsartikel (refereegranskat)abstract
- We present our latest advancements of machine-learned potentials (MLPs) based on the neuroevolution potential (NEP) framework introduced in Fan et al. [Phys. Rev. B 104, 104309 (2021)] and their implementation in the open-source package gpumd. We increase the accuracy of NEP models both by improving the radial functions in the atomic-environment descriptor using a linear combination of Chebyshev basis functions and by extending the angular descriptor with some four-body and five-body contributions as in the atomic cluster expansion approach. We also detail our efficient implementation of the NEP approach in graphics processing units as well as our workflow for the construction of NEP models and demonstrate their application in large-scale atomistic simulations. By comparing to state-of-the-art MLPs, we show that the NEP approach not only achieves above-average accuracy but also is far more computationally efficient. These results demonstrate that the gpumd package is a promising tool for solving challenging problems requiring highly accurate, large-scale atomistic simulations. To enable the construction of MLPs using a minimal training set, we propose an active-learning scheme based on the latent space of a pre-trained NEP model. Finally, we introduce three separate Python packages, viz., gpyumd, calorine, and pynep, that enable the integration of gpumd into Python workflows.
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