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Atmospheric CH 4 is the second-largest anthropogenic contributor to global warming. However, its emissions, components, spatial–temporal variations and projected changes still remain largely uncertain from city to national scales. CH 4 emissions from waste treatment (including solid waste landfills, solid waste incineration and sewage) account for >50 % of total anthropogenic CH 4 emissions at the city scale, and considering the high temperature sensitivity of CH 4 emission factors (EFs) to biological-process-based sources such as waste treatment, large differences will occur when estimating future CH 4 emissions under different global warming scenarios. Furthermore, the relationships between temperature and waste treatment CH 4 emissions have only been studied in a few site-specific studies and lack representativity for whole cities, which contain various biophysical conditions and show heterogeneous distribution. The above factors cause uncertainty in the evaluation of city-scale CH 4 emissions (especially from waste treatments), and projected changes still remain unexplored. Here we conduct the first tower-based CH 4 observation network with three sites in Hangzhou, which is located in the developed Yangtze River Delta (YRD) area and ranks as one of the largest megacities in China. We found the a priori total annual anthropogenic CH 4 emissions and those from waste treatment were overestimated by 36.0 % and 47.1 % in Hangzhou, respectively. In contrast, the total emissions in the larger region, i.e., Zhejiang Province or the YRD area, were slightly underestimated by 7.0 %. Emissions from waste treatment showed obvious seasonal patterns following air temperature. By using the linear relationship constructed between monthly waste treatment CH 4 emissions and air temperature, we find the waste treatment EFs increase by 38 %–50 % with temperature increases of 10 ∘ C. Together with projected temperature changes from four climate change scenarios, the global-warming-induced EFs in Hangzhou will increase at the rates of 2.2 %, 1.2 %, 0.7 % and 0.5 % per decade for IPCC AR5 (Intergovernmental Panel on Climate Change, the Fifth Assessment Report) RCP (Representative Concentration Pathway) 8.5, RCP6.0, RCP4.5 and RCP2.6 scenarios, respectively. And the EFs will finally increase by 17.6 %, 9.6 %, 5.6 % and 4.0 % at the end of this century. Additionally, the derived relative changes in China also show high heterogeneity and indicate large uncertainty in projecting future national total CH 4 emissions. Hence, we strongly suggest temperature-dependent EFs and the positive feedback between global warming and CH 4 emissions should be considered in future CH 4 emission projections and climate change models. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenide (TMD) has emerged as an effective optoelectronics material due to its novel optical properties. Understanding the role of defects in exciton kinetics is crucial for achieving high-efficiency TMD devices. Here, we observe defects induced anomalous power dependence exciton dynamics and spatial distribution in hexagonal heterogeneous WS2. With transient absorption microscopy study, we illustrate that these phenomena originate from the competition between radiative and defect-related non-radiative decays. To understand the physics behind this, a decay model is introduced with two defect-related channels, which demonstrates that more excitons decay through non-radiative channels in the dark region than the bright region. Our work reveals the mechanisms of anomalous exciton kinetics by defects and is instrumental for understanding and exploiting excitonic states in emerging 2D semiconductors. [ABSTRACT FROM AUTHOR]

PM2.5 samples were collected in Hangzhou, eastern China, during the winter and summer of 2016 and 2018. Concentrations of water-soluble ions, elemental carbon (EC), and organic carbon (OC) in PM2.5 were determined. By comparing these data with previous observations, we analyzed the concentrations, variational trends, and main sources of PM2.5 and its dominant chemical components in Hangzhou since the implementation of the Air Pollution Prevention and Control Action Plan. The results indicate that the concentrations of PM2.5 and its main components have shown a declining trend since 2013, which exemplifies the significant effect of the Action Plan on the reduction of PM2.5 pollution in Hangzhou. The contribution of secondary inorganic aerosol (SIA) to PM2.5 in winter showed an increasing trend, and the percentage of SIA in PM2.5 was significantly higher in Hangzhou than in other Chinese cities reported in recent years, which showed that secondary pollution was prominent in Hangzhou. During winter 2018 and 2016, sulfate decreased by 40% and 14%, respectively, compared to that in the same period in 2013. This indicates that the impact of coal combustion emission on PM2.5 pollution has been significantly reduced in Hangzhou since the implementation of the Action Plan. The ratio of nitrate to sulfate increased in winter (winter 2018, 1.87; winter 2016, 1.44; winter 2013, 0.89), indicating that the relative contribution of motor vehicle emissions to PM2.5 is increasing in Hangzhou. The poor correlation and high ratio of OC and EC indicated that there was strong secondary organic carbon formation in summer in Hangzhou. [ABSTRACT FROM AUTHOR]

Metallic nanoparticle-over-mirror (NPOM) represents as a versatile plasmonic configuration for surface enhanced spectroscopy, sensing and light-emitting metasurfaces. However, experimentally identifying the high-order localized surface plasmon modes in NPOM, especially for the best plasmonic material silver, is often hindered by the small scattering cross-section of high-order plasmon modes and the poor reproducibility of the spectra across different NPOMs, resulted from the polyhedral morphology of the colloidal nanoparticles or the rough surface of deposited polycrystalline metals. In this study, we identify the high-order localized surface plasmon modes in silver NPOM by using differential reflection spectroscopy. We achieved reproducible single-particle absorption spectra by constructing uniform NPOM consisting of silver nanospheres, single-crystallized silver microplates, and a self-assembled monolayer of 1,10-decanedithiol. For comparison, silver NPOM created from typical polycrystalline films exhibits significant spectral fluctuations, even when employing template stripping methods to minimize the film roughness. Identifying high-order plasmon modes in the NPOM configuration offers a pathway to construct high-quality plasmonic substrates for applications such as colloidal metasurface, surface-enhanced Raman spectroscopy, fluorescence, or infrared absorption.

Background: Limited evidence is available on the health effects of particulate matter with an aerodynamic diameter of <1 μm (PM 1 ), mainly due to the lack of its ground measurement worldwide., Objectives: To identify and examine the mortality risks and mortality burdens associated with PM 1 , PM 2.5 , and PM 10 in Zhejiang province, China., Methods: We collected daily data regarding all-cause (stratified by age and gender), cardiovascular, stroke, respiratory, and chronic obstructive pulmonary disease (COPD) mortality, and PM 1 , PM 2.5 , and PM 10 , from 11 cities in Zhejiang province, China during 2013 and 2017. We used a quasi-Poisson regression model to estimate city-specific associations between mortality and PM concentrations. Then we used a random-effect meta-analysis to pool the provincial estimates. To show the mortality burdens of PM 1 , PM 2.5 , and PM 10 , we calculated the mortality fractions and deaths attributable to these PMs., Results: Daily concentrations of PM 1 , PM 2.5 , and PM 10 ranged between 0-199 μg/m 3 , 0-218 μg/m 3 , and 0-254 μg/m 3 , respectively; Mortality effects were significant in lag 0-2 days. The relative risks for all-cause mortality were 1.0064 (95% CI: 1.0034, 1.0094), 1.0061 (95% CI: 1.0034, 1.0089), and 1.0060 (95% CI: 1.0038, 1.0083) associated with a 10 μg/m 3 increase in PM 1 , PM 2.5, and PM 10 , respectively. Age- and gender-stratified analysis shows that elderly people (aged 65+) and females are more sensitive to PMs. The mortality fractions of all-cause mortality were estimated to be 2.39% (95% CI: 1.28, 3.48) attributable to PM 1 , 2.53% (95% CI: 1.42, 3.63) attributable to PM 2.5 , and 3.08% (95% CI: 1.95, 4.19) attributable to PM 10 . The ratios of attributable cause-specific deaths for PM 1 /PM 2.5 , PM 1 /PM 10 , and PM 2.5 /PM 10 were higher than the ratios of their respective concentrations., Conclusions: PM 1 , PM 2.5 and PM 10 are risk factors of all-cause, cardiovascular, stroke, respiratory, and COPD mortality. PM 1 accounts for the vast majority of short-term PM 2.5 - and PM 10 -induced mortality. Our analyses support the notion that smaller size fractions of PM have a more toxic mortality impacts, which suggests to develop strategies to prevent and control PM 1 in China, such as to foster strict regulations for automobile and industrial emissions., (Copyright © 2018 Elsevier Ltd. All rights reserved.)