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[Display omitted] • The multichannel Airy beam generator can independently generate the Airy beams for circular polarized and linear polarized waves. • The multichannel beam focusing for circular polarized and linear polarized waves is realized by combining two multichannel Airy beam generators. • The multichannel Airy beam generator is constructed through the antenna theory analysis and the Jones matrix analysis. • The generated Airy beams possess the obvious diffraction-free, self-bending and self-healing features in the broad frequency band. • The low channel crosstalk ensures the high quality of the Airy beams generated simultaneously in three polarization channels. The Airy beam has intrigued long-held research interests and developed various striking applications attributed to the unprecedented diffraction-free, self-bending and self-healing properties. Metasurfaces with superior design freedom and small structure size open a fire-new avenue for generating efficient and broadband Airy beam. Nevertheless, most existing Airy beam generators can only respond to one polarization state of electromagnetic waves and produce the single Airy beam, which immensely limit the serviceability and utilization of the Airy beam generators. Herein, an inspiring strategy of multichannel Airy beam generator based on the multichannel amplitude and phase controlled metasurface is proposed to independently generate the Airy beams for linear polarized waves in 20–24 GHz and orthogonal circular polarized waves in 12–14 GHz and 15–17 GHz. Notably, an appealing paradigm of multichannel beam focusing can be realized by the integrated multichannel Airy beam generator, which possesses strong ability to circumvent the obstacle owing to the self-healing feature of the Airy beam. A proof-of-concept prototype is constructed to verify the feasibility of our methodology, and multitudinous simulations and experiments are in excellent accordance with our theoretical predictions. This novel design of multichannel Airy beam generator will have tremendous application potential in sensing, communication and other multifunctional metadevices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Rayleigh-Sommerfeld diffraction theory and the diffractive neural network algorithm are used to construct the multiplexing meta-hologram. • Low channel crosstalk of the designed helicity-assisted meta-atom ensures the high fidelity of the reconstructed multiple images. • The multiplexing meta-hologram is proposed to independently and simultaneously reconstruct four images in three amplitude-phase channels and one phase-only channel. • The multiplexing meta-hologram can theoretically achieve perfect holography in sixteen imaging channels by easily rotating, mirroring, and arranging the structures. • The multiplexing meta-hologram is able to realize information display, storage and encryption by encoding all imaging channels. Holography has been continuously spurring tremendous interest of researchers attributed to its unparalleled capability of photographically reconstructing the desired images. Based on the metasurfaces with multiple degrees of freedom, multiplexing meta-holograms are experiencing the research upsurge because of enormous application potential. However, existing multiplexing meta-holograms cannot tailor the amplitude information, and possess limited imaging channels and high channel crosstalk, which hinder the improvement of information capacity and imaging quality of multiplexing meta-holograms. Herein, an innovative multiplexing meta-hologram based on the helicity-assisted meta-atoms is proposed, which can perfectly reconstruct four independent images by altering the working frequency, polarization state and propagation direction of incident waves, and theoretically realize the holography in sixteen different channels by easily rotating, mirroring, and arranging the structures of meta-atoms. Numerous simulations and experiments collectively corroborate the feasibility of our methodology, and the quantitative analyses verify the high fidelity of the reconstructed images, which results from the low crosstalk between the amplitude modulation and phase modulation in different imaging channels. This inspiring strategy of multiplexing meta-hologram with large channel capacity and high imaging quality will have promising application prospects in information display, storage and encryption, and provide an alternative path for the design of multifunctional microwave devices. [ABSTRACT FROM AUTHOR]

The gaseous or particulate forms of divalent mercury (HgII) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux (FLX). In the new nested-grid GEOS-Chem model, we try to modify the HgII gas-particle partitioning relationship with synchronous and hourly observations at four sites in China. Observations of gaseous oxidized Hg (GOM), particulate-bound Hg (PBM), and PM 2.5 were used to derive an empirical gas-particle partitioning coefficient as a function of temperature (T) and organic aerosol (OA) concentrations under different relative humidity (RH). Results showed that with increasing RH, the dominant process of HgII gas-particle partitioning changed from physical adsorption to chemical desorption. And the dominant factor of HgII gas-particle partitioning changed from T to OA concentrations. We thus improved the simulated OA concentration field by introducing intermediate-volatility and semi-volatile organic compounds (I/SVOCs) emission inventory into the model framework and refining the volatile distributions of I/SVOCs according to new filed tests in the recent literatures. Finally, normalized mean biases (NMBs) of monthly gaseous element mercury (GEM), GOM, PBM, WFLX were reduced from −33%–29%, 95%–300%, 64%–261%, 117%–122% to −13%–0%, −20%–80%, −31%–50%, −17%–23%. The improved model explains 69%–98% of the observed atmospheric Hg decrease during 2013–2020 and can serve as a useful tool to evaluate the effectiveness of the Minamata Convention on Mercury. [ABSTRACT FROM AUTHOR]

Abstract: Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature. [Copyright &y& Elsevier]

Abstract: Graphene, a new member of carbon family, has been prepared, characterized and used as adsorbent to remove phenol from aqueous solution. The effect parameters including pH, dosage, contact time, and temperature on the adsorption properties of phenol onto graphene were investigated. The results showed that the maximum adsorption capacity can reach 28.26mg/g at the conditions of initial phenol concentration of 50mg/L, pH 6.3 and 285K. Adsorption data were well described by both Freundlich and Langmuir models. The kinetic study illustrated that the adsorption of phenol onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of phenol onto graphene was endothermic and spontaneous. [Copyright &y& Elsevier]

We describe a facile synthesis of Mn 3 O 4 nanoplates (NPs)-anchored graphene microspheres (GSs) and their applications as electrode materials for supercapacitors. The use of GSs as substrate significantly improve the electrochemical performance of Mn 3 O 4 , which can be attributed to unique spherical structure of graphene and excellent stability and anti-reunion of Mn 3 O 4 NPs. The success of this synthesis depends on the in situ reduction of Mn cations by carbon from GSs under hydrothermal conditions. The resultant Mn 3 O 4 NPs with an average thickness of 37 nm were uniformly distributed on the surface of GSs. Material characterizations, including XRD, Raman, FTIR and XPS, have been performed to confirm their shape, composition and structure. As a positive material, the as-prepared Mn 3 O 4 NPs/GSs composites exhibited excellent electrochemical property in a three-electrode system. In particular, their specific capacitance reached as high as 317 F g −1 at a scan rate of 10 mV s −1 , and a remarkable stability (about 100% retention of its initial capacitance) was achieve after 4000 galvanostatic charge-discharge cycles at the current density of 2 A g −1 . Therefore, Mn 3 O 4 NPs/GSs can have been used as an electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • We propose the orthogonality-simplified machine learning framework to design vectorial-holography metasurface. • A structure with orthogonality is designed to independently control x- and y- polarized waves. • Resistors are embedded in meta -atoms to tailor amplitude. • The design of machine learning architecture is simplified based on the physical principle of orthogonality. • The vectorial-holography metasurface is designed by customizing the polarization. Metasurfaces can provide unprecedented degree of freedom in manipulating electromagnetic waves and have been introduced to holography. Aiming to explore the full capability for information presentation, vectorial metasurface holography is sprung up, which exhibits mesmerizing capability in carrying information compared with scalar counterpart. However, the more flexible modulation means the more complex design dimension, which hinders the development of vectorial metasurface holography. In this work, we propose an orthogonal I-shaped structure embedded with resistors to synthesize arbitrary polarization with less crosstalk. Benefiting from the independent control of phase and amplitude on orthogonal base, the orthogonality-simplified machine learning framework is employed to assist vectorial metasurface holography design. As a proof-of-concept, a vectorial metasurface holography carrying multi-polarization information was designed, simulated and measured. All the results exhibit a high degree of consistency, which fully demonstrates the effectiveness of our design. Encouragingly, our method paves a new route to simplify machine learning framework based on physical significance, which can be handily extended to more functional structures. [ABSTRACT FROM AUTHOR]

Abstract: China's air pollution control policies during the 12th Five Year Plan (2011–2015) are characterized by the targets of 10% nitrogen oxides (NO x ) reduction and 8% sulfur dioxide (SO2) reduction from the 2010 levels. In this study, the Community Multi-scale Air Quality (CMAQ) modeling system was used to evaluate the impact of only SO2, only NO x , and joint SO2/NO x control measures on particulate matter pollution, the greatest concern for urban air quality in China. Four emission scenarios were developed for 2015, including a business-as-usual scenario, a reference NO x control scenario based on the governmental plan, an accelerated NO x control technology scenario, and a scenario assuming joint controls of NO x and SO2 based on the governmental plan. Under the planned NO x control measures, the annual mean concentrations of particulate matter less than or equal to 2.5 μm (PM2.5) decline by 1.5–6 μg m−3, i.e. 1.6%–8.5%, in the majority of eastern China. The largest reduction occurs in the middle reach of the Yangtze River. Under accelerated NO x control measures, the annual average PM2.5 concentration reductions (compared with the business-as-usual scenario) in eastern China are 65% higher than the reductions under planned control measures. The unusual increase of PM2.5 concentrations in the North China Plain and the Yangtze River Delta during January after the reductions of NO x emissions was an integrated effect of excessive NO x , the ammonia-rich inorganic aerosol chemistry, and the non-methane volatile organic compounds (NMVOC) sensitive photochemical regime. Under the joint controls of NO x and SO2, the annual mean PM2.5 concentrations decline over 3 μg m−3, i.e. 3.2%–13%, in the majority of eastern China, and some areas in the middle reach of the Yangtze River have reductions as large as 6–8.3 μg m−3, i.e. 5.0%–13%. The average PM2.5 concentration reductions in eastern China are 1.20 μg m−3, 3.14 μg m−3, 3.57 μg m−3, 4.22 μg m−3 in January, May, August, and November, respectively. The corresponding declining rates are 2.3%, 12.2%, 14.3%, and 8.1%, respectively. More stringent policies should be implemented in winter to reduce the heavy pollution periods. The annual average PM2.5 concentration reductions in three major city clusters are comparable with the average reductions of eastern China. Stringent regional control policies are required for the significant improvement of particulate air quality in major city clusters. [Copyright &y& Elsevier]

Abstract: A new adsorbent manganese oxide coated graphene oxide (MOGO) was synthesized and characterized by TEM, XRD, FTIR, and BET analysis. The effects of different parameters such as pH, adsorbent dose, contact time and temperature were studied to understand the adsorption behavior of the adsorbent under various conditions. Adsorption studies revealed that optimum removal of fluoride occurred in a pH range of 5.5–6.7. The Langmuir isotherm model demonstrated that the maximum fluoride adsorption capacity of MOGO was 11.93mg/g and 8.34 times higher than that of GO. The kinetic adsorption data were analyzed using the pseudo first-order model, the pseudo second-order model and the intra-particle diffusion model. Thermodynamic adsorption results showed that adsorption of fluoride by MOGO was a spontaneous and endothermic process. [Copyright &y& Elsevier]

The serious fine particle (PM 2.5) pollution in China causes millions of premature deaths. Driven by swift economic growth and stringent control policies, air pollutant emissions in China have changed significantly in the last decade, but the change in the source contribution of PM 2.5 -related health impacts remains unclear. In this study, we develop a multi-pollutant emission inventory in China for 2005–2015, and combine chemical transport modeling, ambient/household exposure evaluation and health impact assessment to quantify the contribution of eight emission sectors to PM 2.5 exposure and associated health risk. From 2005 to 2015, the mortality due to PM 2.5 from ambient air pollution (AAP) decreases from 1.04 (95% confidence interval, 0.84–1.25) million to 0.87 (0.70–1.04) million. The agricultural sector contributes 25% and 32% to ambient PM 2.5 -attributed mortality in 2005 and 2015, respectively, representing the largest contributor during this period. The contribution of power plants drops monotonously from 13% to 6%. The percentage contribution of industrial process drops significantly while the contribution of industrial combustion stays the same level. The overall contribution of industry is still as large as 26% in 2015 in spite of strict control measures. For transportation, despite strict emission standards, its contribution increases remarkably due to the rapid growth of vehicle population. When both ambient and household PM 2.5 exposures are taken into account, the mortality due to integrated population-weighted exposure to PM 2.5 (IPWE) drops from 1.78 (1.46–2.09) million in 2005 to 1.28 (1.05–1.52) million in 2015. Most of the IPWE reduction comes from domestic combustion as a result of urbanization and improved income, whereas this sector remains the largest contributor (58%) to IPWE-related health risk in 2015. Our results suggest that the government should dynamically adjust the air pollution control strategy according to the change in source contributions. Domestic combustion and agriculture should be prioritized considering their predominant contributions to mortality and the lack of effective control policies. More stringent control measures for industry and transportation are necessary since the existing policies have not adequately reduced their health impacts. Electricity production is no longer the top priority of air pollution control policies given its lower health impact compared with that of other sources. • We analyze source contribution to PM 2.5 exposure and related mortality in China. • Domestic combustion and agriculture contribute most but lack control policies. • More stringent control measures are needed for industry and transportation. • Electricity is no longer the top priority of air pollution control policies. [ABSTRACT FROM AUTHOR]