Suchergebnisse

Due to rapid urbanization, industrialization and motorization, a large number of Chinese cities are affected by heavy air pollution. In order to explore progress, remaining challenges, and sustainability of air pollution control in the Beijing-Tianjin-Hebei (BTH) region after 2013, a mixed method analysis was undertaken. The quantitative analysis comprised an overview of air quality management in the BTH region. Semi-structured expert interviews were conducted with 12 stakeholders from various levels of government and research institutions who played substantial roles either in decision-making or in research and advising on air pollution control in the BTH region. The results indicated that with the stringent air pollution control policies, the air quality in BTH meets the targets of the Air Pollution Prevention and Control Action Plan. However, improvements vary across the region and for different pollutants. Although implementation has been decisive and was at least in parts effectively enforced, significant challenges remained with regard to industrial and traffic emission control, and national air quality limits continued to be significantly exceeded and competing development interests remained mainly unsolved. There were also concerns about the sustainability of the current air pollution control measures especially for industries due to the top-down enforcement, and the associated large burden of social cost including unemployment and social inequity resulting industrial restructuring. Better mechanisms for ensuring cross-sectoral coordination and for improved central-local government communication were suggested. Further suggestions were provided to improve the conceptual design and effective implementation of respective air pollution control strategies in BTH. Our study highlights some of the major hurdles that need to be addressed to succeed with a comprehensive air pollution control management for the Chinese mega-urban agglomerations.

Due to rapid urbanization, industrialization and motorization, a large number of Chinese cities are affected by heavy air pollution. In order to explore progress, remaining challenges, and sustainability of air pollution control in the Beijing-Tianjin-Hebei (BTH) region after 2013, a mixed method analysis was undertaken. The quantitative analysis comprised an overview of air quality management in the BTH region. Semi-structured expert interviews were conducted with 12 stakeholders from various levels of government and research institutions who played substantial roles either in decision-making or in research and advising on air pollution control in the BTH region. The results indicated that with the stringent air pollution control policies, the air quality in BTH meets the targets of the Air Pollution Prevention and Control Action Plan. However, improvements vary across the region and for different pollutants. Although implementation has been decisive and was at least in parts effectively enforced, significant challenges remained with regard to industrial and traffic emission control, and national air quality limits continued to be significantly exceeded and competing development interests remained mainly unsolved. There were also concerns about the sustainability of the current air pollution control measures especially for industries due to the top-down enforcement, and the associated large burden of social cost including unemployment and social inequity resulting industrial restructuring. Better mechanisms for ensuring cross-sectoral coordination and for improved central-local government communication were suggested. Further suggestions were provided to improve the conceptual design and effective implementation of respective air pollution control strategies in BTH. Our study highlights some of the major hurdles that need to be addressed to succeed with a comprehensive air pollution control management for the Chinese mega-urban agglomerations.

Reducing salt intake is one of the most cost-effective interventions to improve population health due to the subsequent reductions in blood pressure. Countries are introducing programs to lower salt consumption. Such programs usually focus on reducing salt in packaged foods and meals alongside campaigns to change consumer behavior. Thus, this paper provides an overview of the rationale for and evidence supporting the use of salt substitutes. Cur­rent approaches to salt reduction are insufficient, and more innovative solutions need to be identified. There is good evidence that salt substitutes, where some of the sodium is replaced with potassium, are effective to lower sodium total intake. The main challenge is to understand the pathways to market for salt substitutes. How do we implement programs to promote salt substitutes in different countries? What levels of government intervention are required? With more research and government investment, salt substitutes could be a game changer for increasing the impact of strategies to reduce population salt intake. ; Reducing salt intake is one of the most cost-effective interventions to improve population health due to the subsequent reductions in blood pressure. Countries are introducing programs to lower salt consumption. Such programs usually focus on reducing salt in packaged foods and meals alongside campaigns to change consumer behavior. Thus, this paper provides an overview of the rationale for and evidence supporting the use of salt substitutes. Cur­rent approaches to salt reduction are insufficient, and more innovative solutions need to be identified. There is good evidence that salt substitutes, where some of the sodium is replaced with potassium, are effective to lower sodium total intake. The main challenge is to understand the pathways to market for salt substitutes. How do we implement programs to promote salt substitutes in different countries? What levels of government intervention are required? With more research and government investment, salt ...

Aerosol pollution in eastern China is an unfortunate consequence of the region's rapid economic and industrial growth. Here, sun photometer measurements from seven sites in the Yangtze River Delta (YRD) from 2011 to 2015 were used to characterize the climatology of aerosol microphysical and optical properties, calculate direct aerosol radiative forcing (DARF) and classify the aerosols based on size and absorption. Bimodal size distributions were found throughout the year, but larger volumes and effective radii of fine-mode particles occurred in June and September due to hygroscopic growth and/or cloud processing. Increases in the fine-mode particles in June and September caused AOD440 nm > 1.00 at most sites, and annual mean AOD440 nm values of 0.71–0.76 were found at the urban sites and 0.68 at the rural site. Unlike northern China, the AOD440 nm was lower in July and August (∼ 0.40–0.60) than in January and February (0.71–0.89) due to particle dispersion associated with subtropical anticyclones in summer. Low volumes and large bandwidths of both fine-mode and coarse-mode aerosol size distributions occurred in July and August because of biomass burning. Single-scattering albedos at 440 nm (SSA440 nm) from 0.91 to 0.94 indicated particles with relatively strong to moderate absorption. ; This work was supported by a grant from the National Key R & D Program Pilot Projects of China (2016YFA0601901), the National Natural Science Foundation of China (41590874, 41475138 & 41375153), the Natural Science Foundation of Zhejiang Province (LY16010006), the CAMS Basis Research Project (2016Z001 & 2014R17), the Climate Change Special Fund of CMA (CCSF201504), the Special Project of Doctoral Research supported by Liaoning Provincial Meteorological Bureau (D201501), the Hangzhou Science and Technology Innovative project (20150533B17) and the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 262254.

Perovskite quantum dots (QDs) are of interest for solution-processed lasers; however, their short Auger lifetime has limited lasing operation principally to the femtosecond temporal regime the photoexcitation levels to achieve optical gain threshold are up to two orders of magnitude higher in the nanosecond regime than in the femtosecond. Here the authors report QD superlattices in which the gain medium facilitates excitonic delocalization to decrease Auger recombination and in which the macroscopic dimensions of the structures provide the optical feedback required for lasing. The authors develope a self-assembly strategy that relies on sodiumd—an assembly director that passivates the surface of the QDs and induces self-assembly to form ordered three-dimensional cubic structures. A density functional theory model that accounts for the attraction forces between QDs allows to explain self-assembly and superlattice formation. Compared to conventional organic-ligand-passivated QDs, sodium enables higher attractive forces, ultimately leading to the formation of micron-length scale structures and the optical faceting required for feedback. Simultaneously, the decreased inter-dot distance enabled by the new ligand enhances exciton delocalization among QDs, as demonstrated by the dynamically red-shifted photoluminescence. These structures function as the lasing cavity and the gain medium, enabling nanosecond-sustained lasing with a threshold of 25 μJ cm–2. ; C.Z., J.M.P., and T.Z. contributed equally to this work. L.Z. and H.D. acknowledge the National Natural Science Foundation of China (Grant Nos. 61875256, 61675219, and 91950201). This work was partially funded by the Natural Sciences and Engineering Research Council of Canada (NSERC). M.I.S. acknowledges the support of Banting Postdoctoral Fellowship Program, administered by the Government of Canada. WAXS and SAXS measurements were performed in the Canadian Light Source CLS, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), NSERC, the National Research Council (NRC), the Canadian Institutes ofHealth Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan. The authors acknowledge the technical assistance and scientific guidance of C.-Y. Kim and A. Leontowich at the CLS. The authors also acknowledge the help and useful discussions of A. Johnston, S. Teale, and J. Fan regarding the WAXS and SAXS data. They also acknowledge the useful discussions with R. Sabatini regarding transient PL data. H.D. acknowledges the Youth Top-notch Talent Support Program in Shanghai. The authors again acknowledge the University of Chinese Academy of Sciences (UCAS) Joint Ph.D. Training Program.