In recent years, ground-level ozone pollution in China has become an increasingly prominent problem. This study simulated and analyzed spatiotemporal distribution of ozone and exposure level by the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) models and monitoring data from 1516 national air quality monitoring stations in China during 2015. The simulation results show that the Sichuan Basin, Shandong, Shanxi, Henan, Anhui, Qinghai-Tibetan Plateau, Yangtze River Delta (YRD), Pearl River Delta (PRD) and Beijing-Tianjin-Hebei (BTH) region had relatively high average annual concentrations of ozone. The regions with more than 10% nonattainment days of 160 mu g/m(3) (daily maximum 8-h) are mainly concentrated in BTH, Shandong Peninsula and YRD, where large seasonal variations were also found. Exposure levels were calculated based on population data and simulated ozone concentrations. The cumulative population exposed to daily maximum 8-h concentration greater than or equal to 100 mu g/m(3) was 816.04 million, 61.17% of the total. Three methods were used to estimate the mortality of chronic obstructive pulmonary disease (COPD) attributable to ozone. A comparative study using different exposure concentrations and threshold concentrations found large variations among these methods, although they were all peer-reviewed methods. The estimated mortality of COPD caused by ozone in China in 2015 ranged from 55341 to 80280, which mainly distributed in Beijing, Shandong, Henan, Hubei and Sichuan Province, the YRD and PRD region.
Graphene oxide (GO) coatings on membranes can improve antifouling performance against a variety of microorganisms and organics. However, the effects of GO coatings on mineral scaling were not investigated. Here gypsum scaling on bare (ESPA2) and GO-modified thin-film polyamide membranes (ESPA2-GO) followed by cleaning with deionized (DI) water were investigated with a bench-scale reverse osmosis setup. The flux decline caused by gypsum scaling on ESPA2-GO was slightly reduced than on ESPA2. This is because the ESPA2-GO membrane is more hydrophilic than ESPA2, indicating a higher energy barrier for heterogeneous nucleation and/or the deposition of gypsum on it. Moreover, the more negatively charged ESPA2-GO membrane lead to stronger electrostatic repulsive forces between the membrane and the negatively charged gypsum particles and thus further inhibiting gypsum deposition onto membranes. Interestingly, during the cleaning process, smaller flux recovery was observed for ESPA2-GO. This is because ESPA2-GO surfaces have higher densities of carboxyl (–COOH) groups, which form complexes with Ca2+, building strong bonds between GO coatings and gypsum. This study provided unique insights on the physicochemical interactions among membrane, the scaling mineral, and aqueous species, which can help the rational design of coatings for better simultaneous anti-scaling and anti-fouling performances.
Yang T, Gong J, Zhang H, Zou L, Shi L, Li X. HeavyGuardian: Separate and Guard Hot Items in Data Streams, in Proceedings of the 24th ACM SIGKDD International Conference on Knowledge Discovery & Data Mining, KDD 2018, London, UK, August 19-23, 2018.; 2018:2584–2593. link
Phosphate is added to Pb-contaminated soils to induce lead immobilization through lead phosphate precipitation. Organic coatings on soils, which may affect heterogeneous lead phosphate nucleation, can impact the effectiveness of lead immobilization. Here, SiO2 surfaces were coated with silanol self-assembled thin films terminated with −COOH and −OH functional groups to act as model organic coatings on soil particles. Using grazing incidence small-angle X-ray scattering (GISAXS), heterogeneous lead phosphate nucleation on coatings was measured from mixed Pb(NO3)2 and Na2HPO4/NaH2PO4 solutions at pH 7 with varied ionic strengths (IS = 0.58, 4, and 11 mM). Raman spectroscopy identified the homogeneous precipitates in solution as hydroxylpyromorphite (Pb5(PO4)3OH). The smallest lead phosphate nuclei (4.5 ± 0.5 nm) were observed on −COOH coatings, which resulted from the highest level of lead and phosphate ion adsorption on −COOH coatings. The IS of the solution also affected the sizes of the heterogeneous precipitates on −COOH coating, with smaller nuclei (1.3 ± 0.4 nm) forming under higher IS (4 and 11 mM). This study provided new findings that can improve our understanding of lead immobilization in contaminated soil environments.
Despite the rapid progress that has been made in increasing the power conversion efficiency (PCE) of organic solar cells (OSCs) over the past decade, it is a challenge to realize efficient and environment-friendly OSCs. In this contribution, all polymer solar cells were fabricated with a blend of poly[4,8-bis(5-(2ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate](PTB7Th) donor and vinylene-bridged perylenediimide-based polymer (PDI-V) acceptor, in which non-halogenated tetrahydrofuran (THF) was used as the host solvent. A conventional ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/PTB7-Th:PDI-V/zirconium device structure of ITO/poly(3,4acetylacetonate(ZrAcac)/Al was employed, where PEDOT:PSS functioned as the hole transporting layer (HTL) and ZrAcac functioned as the electron transporting layer (ETL). The mixed solution of PTB7-Th and PDI-V was spin cast on the top of PEDOT:PSS layer to form the active layer. After that, ZrAcac solution was spin cast on the top of PTB7-Th:PDI-V layer. Different thermal annealing temperatures were used to optimize the active layer morphology. In details, OSCs without thermal annealing showed a PCE of 7.1%, with a short-circuit current (JSC) of 14.9 mA/cm2, an open-circuit voltage (VOC) of 0.74 V, and a fill factor (FF) of 64%. The devices annealed at 120 °C showed a high PCE of 8.1% with a JSC of 15.5 mA/cm2, a VOC of 0.74 V, and a FF of 70%. Further increasing the annealing temperature to 150 °C led to decreased FF and thereby a relatively lower PCE (7.4%). To the best of our knowledge, the PCE of ~ 8.1% is one of the highest PCE values reported in the literature so far for all polymer solar cells. The high and balanced hole and electron mobility partially contributed to such a high performance. These results suggest that THF as good non-halogenated solvent can be used to fabricate high-performance all polymer solar cells. Higher efficiency can be achieved for OSCs with THF solvent when better polymer acceptors are employed. 以聚合物PTB7-Th为给体、聚合物PDI-V为受体和四氢呋喃为溶剂，构筑了全聚合物太阳能电池.PTB7-Th与PDI-V光谱互补，有效地拓宽了活性层在可见光区的吸收范围，这有利于提高光电流.在器件优化过程中，发现热退火的方法可以有效地提高器件的光伏性能.尽管热退火处理对器件的开路电压影响不大，但是可以一定程度上提高器件的短路电流和填充因子，从而将电池的效率从7.1%提高到8.1%.8.1%的效率也是目前采用非卤素溶剂加工的基于苝酰亚胺类聚合物受体电池效率的最高值.该实验结果表明，四氢呋喃作为一种低毒性的有机非卤素溶剂，可以用来制备高性能有机光伏器件.