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[Display omitted] With the increased usage of electromagnetic microwaves (EM) in wireless communication technology, the problem of electromagnetic radiation pollution has grown dramatically. This study successfully prepared novel Co/C magnetic nanocomposite fibers for EM absorption using the electrospinning and carbonization methods. The morphology, composition, magnetic properties, and EM absorption performance were extensively characterized. This material shows exceptional EM absorption performance, achieving −72.01 dB (at 2.08 mm) for minimum reflection loss (RL min) and 5.4 GHz (at 1.68 mm) for effective absorption bandwidth (EAB). The performance surpasses not only any single precursor but also stands as the best in similar investigations. It can be attributed to the microstructure of magnetic Co nanoparticles encapsulated in carbon nanofibers and the macrostructure of cross-linked three-dimensional (3D) conductive networks. The combination of these structures resulted in excellent dielectric loss, magnetic loss, and impedance matching. This research offers new insights into the production of one-dimensional (1D) carbon-based absorbers, while also establishing a theoretical foundation for exploring the application potential of this material. These findings may contribute to the development of more efficient and practical EM absorption materials in the future. [ABSTRACT FROM AUTHOR]

With the development of information technology, the problem of electromagnetic pollution was increasingly prominent. At present, it had brought serious harm to electronic equipment and biology. Microwave absorption (MA) materials were the key to solve this problem. One-dimensional (1D) carbon-based magnetic composites were prepared by compounding with carbon materials, which improved the deficiency of ferromagnetic MA materials. In this review, the unique advantages of 1D carbon-based magnetic composites were discussed in detail. Firstly, the preparation methods of carbon fibers with different structures were reviewed, including the important roles of these structures in MA. After that, the properties of carbon nanotubes (CNTs) combined with different magnetic materials were introduced. The biomass-derived 1D carbon materials possessed the unique structure, which was obtained difficultly by artificial ways. Their advantages and current progress for MA were analyzed in detail. Finally, according to the current development of MA materials, the challenges and research prospects of 1D carbon-based magnetic composites were discussed, and some suggestions were proposed as well. [ABSTRACT FROM AUTHOR]

Electrospinning is one of the attractive technologies for fabrication carbon-based fibers due to its high efficiency, component controllability and functionalities. Here, a multi-step strategy was used for the efficient synthesis of one-dimensional (1D) MOF-derived C@Co/N-doped carbon@polypyrrole (C@Co/NC@PPy) composite fibers. The composite fibers synthesized by introducing the electrospinning method possessed unique structural anisotropy and multiple absorption mechanisms. The electromagnetic parameters, the absorption performance and the internal mechanisms of samples were thoroughly illustrated. By adjusting the filler loadings of samples, the electromagnetic wave (EMW) absorption could be optimized. The C@Co/NC@PPy with 35 wt% filler loading showed the optimal performance. Impressively, with a thickness of merely 1.65 mm, the C@Co/NC@PPy composite fibers delivered high performance with the minimum reflection loss (RL min) of -72.14 dB. Correspondingly, the maximum effective absorption bandwidth (EAB max) could reach 5.6 GHz with the thickness of 1.88 mm. Furthermore, the 35 wt% loading C@Co/NC@PPy composite fibers could reach 14.28 GHz (89.25% of 2–18 GHz) effective absorption, showing the ultrawide absorption. Those positive results forcefully verified that the 1D MOF-derived C@Co/NC@PPy composites showed great potential and superiority as EMW absorption material. [Display omitted] [ABSTRACT FROM AUTHOR]

Wastewater treatment has become a research hot issue in recent decade. Organic dyes as one of the main pollutants can change the water behavior. To deracinate the organic pollutants from wastewater, there are numerous methods have been taken into consideration. Photocatalysis is the promising strategy for the dye degradation with low cost, high efficiency, and environmental friendliness. Hence, a novel one‐dimensional (1D) magnetic Bi2Fe4O9/C@AgBr composite photocatalyst was prepared employing electrospinning, calcination, and deposition–precipitation methods. The morphology and composition of photocatalyst were characterized, as well as the photocatalytic activities of degrading methylene blue (MB) under visible light were investigated. And the results exhibited that the efficiency of Bi2Fe4O9/C@AgBr under visible light for 60 min is 97.4%. After three cycles, the degradation efficiency of MB could still reach 88.0%. Moreover, radical quenching experiment implicated superoxide radical anions as the primary active species responsible for photodegradation of MB. This work provides a new insight into the design of effective photocatalysts for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] Increasing electromagnetic (EM) radiation has driven the rapid development of carbon-based EM wave absorption materials, but the design of light-weight and efficient carbon-based materials remains a huge challenge. Herein, N -doped carbon fibers embedded with CoNi alloy particles (CoNi/C fibers) were synthesized via electrospinning technology and carbonization. Then, conductive polypyrrole-coated CoNi/C fibers (CoNi/C@PPy composites) were synthesized by chemical polymerization. As-synthesized CoNi/C@PPy composites showed outstanding EM wave absorption property due to the synergistic effect between CoNi, N -doped carbon fibers and PPy. The optimal reflection loss (RL) is -68.78 dB (12.90 GHz) with the thickness of 2.43 mm and the low filler loading of 15 wt%. The widest effective absorption bandwidth (EAB) is 5.62 GHz with the thickness of 2.10 mm and the low filler loading of 20 wt%. The outstanding EM wave absorption property is mainly attributed to 3D network structure, great impedance matching and strong dielectric loss. The results showed that embedding magnetic alloy particles in carbon fibers coated with conductive polymers is an effective strategy for constructing efficient lightweight EM wave absorption materials. [ABSTRACT FROM AUTHOR]

[Display omitted] At present, the magnetic metal/carbon composites have been widely explored for microwave absorption (MA), which effectively integrate the characteristics of magnetic and dielectric materials. As a typical material, metal–organic framework (MOF) shows tremendous potential as a precursor or template. However, its development is limited by the inferior impedance matching. Herein, a novel rod-like Fe/Fe 3 O 4 /FeN/N-doped carbon (FON/NC) composite was synthesized via dual-ligand strategy and following calcination. The outer polypyrrole (PPy) shell, obtained by a facile polymerization method, effectively optimized the impedance matching and observably enhanced the MA capacity. Both the multi-component loss mechanism and unique porous core–shell structures of MOF-derived composites were beneficial for microwave attenuation. The effects of filler loadings (20 wt%, 25 wt%, 30 wt% and 35 wt%) on electromagnetic (EM) properties of FON/NC@PPy composites were discussed. Remarkably, as-obtained composites exhibited a minimum reflection loss (RL) value of −60.08 dB at the layer thickness of merely 1.44 mm and the widest effective absorption bandwidth (EAB, RL ≤ −10 dB) of 5.06 GHz at 1.64 mm with 30 wt% filler loading. This work provides a great reference for designing MOF-derived absorbers with high MA performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Advanced microwave absorption (MA) materials have attracted widespread attention to meet the challenges of electromagnetic (EM) pollution. Herein, MgFe 2 O 4 /MgO/C fibers were successfully prepared via electrospinning technology and carbonization, and their surfaces were coated by MoS 2 via hydrothermal method. The EM wave absorption performance of composites was enhanced due to the introduction of MoS 2. The results showed that the EM wave absorption performance of MgFe 2 O 4 /MgO/C could not meet the requirements due to low dielectric loss and poor impedance matching. The performance of the composites was improved after coating of MoS 2 , which showed the strong wave absorption capability and the broad absorption bandwidth. The optimal reflection loss (RL) is −56.94 dB at 9.5 GHz and the effective absorption bandwidth is 3.9 GHz (8.08–11.98 GHz) with a thickness of 2.7 mm. The excellent MA performance can be mainly attributed to excellent synergistic effect between MgFe 2 O 4 /MgO/C and MoS 2. Furthermore, MoS 2 also contributes to dielectric loss and ideal impedance matching. MgFe 2 O 4 /MgO/C@MoS 2 composites may be utilized for lightweight and high-efficient MA materials. [ABSTRACT FROM AUTHOR]

[Display omitted] The conductive networks for electron hopping and migration constructed by one-dimensional (1D) composite absorbers are highly desirable to improve the electromagnetic (EM) wave attenuation capacity. Herein, the Ni@Co/C@polypyrrole (PPy) composites integrating the advantages of component and microstructure were fabricated. The addition of Co/C and PPy effectively optimized the impedance matching and improved the EM attenuation. Under the comprehensive impacts of multiple reflections/scattering, conduction loss and interface polarization, the Ni@Co/C@PPy composites showed superior EM wave absorption with the reflection loss (RL) value of −48.76 dB and the effective absorption bandwidth (EAB) of 5.10 GHz at a corresponding thickness of 2.0 mm. The largest EAB could reach 5.54 GHz (7.24–12.78 GHz) at the thickness of 2.2 mm. This work provides a great reference for fabricating 1D novel EM wave absorption materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Nowadays, ferrites/carbon fibers have attracted considerable attention as microwave absorption materials (MA) due to the synergistic effect between dielectric and magnetic loss. Herein, the ZnFe 2 O 4 /C fibers were fabricated via electrospinning and calcination methods, and then polypyrrole (PPy) successfully coated on the fibers via oxidative polymerization. The ZnFe 2 O 4 /C@PPy composites exhibit enhanced EM wave absorption performance with the loading of 25 wt%. The optimal reflection loss (RL) value is up to −66.34 dB (13.80 GHz) and effective absorption bandwidth (EAB) is 5.74 GHz (11.78–17.52 GHz) with a matching thickness of 1.93 mm. Besides, high-efficient absorption performance of the ZnFe 2 O 4 /C@PPy composites is mainly attributed to the dielectric loss and ideal impedance matching. This study reveals a novel approach to development of ferrites/carbon fibers coated with PPy, and the ZnFe 2 O 4 /C@PPy composites exhibit great potential application as the materials with high-efficient absorption properties. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal-organic framework (MOF) materials have caused widespread concerns in the field of microwave absorption, due to the unique microstructure and electronic state. Herein, the CoZn/C@MoS 2 @polypyrrole (PPy) composites were prepared through MOF self-template method. The MoS 2 sheets and PPy shell incorporated for optimizing impedance matching of two-dimensional (2D) CoZn/C composites. The introduction of MoS 2 sheets and PPy shell endowed the composites with enhanced microwave absorption. The as-prepared CoZn/C@MoS 2 @PPy composites showed a minimum reflection loss (RL) of −49.18 dB with the thickness of 1.5 mm. In addition, the effective absorption bandwidth (EAB, RL values exceeding −10 dB) covered 4.56 GHz, which showed greater performances than CoZn/C composites under a lower thickness (<2 mm). This work not only provides a facile route for fabricating MOF-derived carbon-based composites as microwave absorbers, but also broadens the application of MOF materials. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, one-dimensional (1D) ZnFe 2 O 4 @carbon@MoS 2 /FeS 2 composites were synthesized by hydrothermal method, magnetic-field-induced distillation-precipitation polymerization and high-temperature carbonization. The structure, morphology, composition, magnetic performance and electromagnetic (EM) wave absorbing properties of the composites were systematically studied. The composites show strong microwave absorption (MA) capacity with a minimum reflection loss (RL min) value of −52.5 dB at 13.2 GHz, and have an effective absorption frequency range of 10.10–15.08 GHz with a bandwidth of 4.98 GHz when the thickness is 2.23 mm. It is expected that as-synthesized 1D ZnFe 2 O 4 @carbon@MoS 2 /FeS 2 composites can be a promising EM wave absorption material. [ABSTRACT FROM AUTHOR]

The serious problems of environmental pollution and energy shortage have pushed the green economy photocatalysis technology to the forefront of research. Therefore, the development of an efficient and environmentally friendly photocatalyst has become a hotpot. In this work, magnetic Fe3O4/C/MnO2/C3N4 composite as photocatalyst was synthesized by combining in situ coating with low-temperature reassembling of CN precursors. Morphology and structure characterization showed that the composite photocatalyst has a hollow core–shell flower-like structure. In the composite, the magnetic Fe3O4 core was convenient for magnetic separation and recovery. The introduction of conductive C layer could avoid recombining photo-generated electrons and holes effectively. Ultra-thin g-C3N4 layer could fully contact with coupled semiconductor. A Z-type heterojunction between g-C3N4 and flower-like MnO2 was constructed to improve photocatalytic performance. Under the simulated visible light, 15 wt% photocatalyst exhibited 94.11% degradation efficiency in 140 min for degrading methyl orange and good recyclability in the cycle experiment. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) ZnFe 2 O 4 @SiO 2 (ZS) nanochains were prepared with Stöber method under external magnetic field. Then, 1D ZS nanochains were covered with a uniform polydopamine (PDA) shell, and the pyrolysis process was completed to obtain 1D ZnFe 2 O 4 @SiO 2 @C (ZSC) nanochains. Finally, 1D flower-like ZnFe 2 O 4 @SiO 2 @C@NiCo 2 O 4 (ZSCNC) nanochains were fabricated through a simple hydrothermal method. The carbon layer with strong dielectric loss enabled the 1D ZSC nanochains to achieve an ultra-wide effective absorption bandwidth (EAB) of 6.22 GHz. Compared with the above nanochains, the 1D ZSCNC nanochains showed more excellent microwave absorption (MA) properties because of the unique 1D flower-like architectures having large surfaces and multiple interfaces. The sample loaded with 30 wt% 1D flower-like ZSCNC nanochains showed strong MA performances with a minimum reflection loss (RL) value of −54.29 dB (11.14 GHz) and an EAB of 5.66 GHz (11.94–17.60 GHz) at the thickness of 2.39 mm. The 1D flower-like ZSCNC nanochains with strong absorption, broad absorption bandwidth (almost the entire Ku band) and thin layer has a good application prospect for the absorption of electromagnetic waves in Ku band. [ABSTRACT FROM AUTHOR]

Abstract Atmospheric fine particulate matters (PM 2.5) have raised global concerns because of their markedly adverse effects on public health and environmental quality. In parallel with technological variations and social changes in the evolving industrialization pathways in China, there is an acute need to evaluate the long-term spatiotemporal trend of PM 2.5 concentrations across China after years of elevation. Toward this end, an integrated high-resolution satellite-derived (1998–2016) and ground-measured (2015–2017) PM 2.5 data base was applied. Satellite-derived annual mean PM 2.5 grids were firstly validated via comparison with collocated surface in situ PM 2.5 measurements and were then used for trend analyses. The estimated linear trends from gridded PM 2.5 data indicated that PM 2.5 concentrations in China increased mainly before 2008 and have decreased since then, with prominent decreases observed primarily in south China. To corroborate the satellite-based PM 2.5 trend estimations, surface in situ PM 2.5 measurements from the period from 2015 to 2017 were applied to further evaluate the decreasing rate after 2014, at which time the Chinese "Air Pollution Prevention and Control Action Plan" was enforced. The results revealed that the national mean PM 2.5 concentrations decreased by about 6.5 μg/m3 from 2015 to 2017, with prominent decreases (by a rate of 5–10 μg/m3 per year) observed primarily associated with large PM 2.5 concentrations in Central China, North China, Northeast China, and East China during the period from October to December. Our systematic trend assessment provides a deepened understanding of PM 2.5 variations across China in the past few years in association with the newly promoted action plan and offers a brief guideline for relevant policy making in the future. Highlights • 20-year long PM 2.5 trends are indicative of pollution control thrust in China. • PM 2.5 in China increased mainly before 2008 and have decreased since then. • PM 2.5 concentrations decreased more prominently in Central China than other regions. • Most significant decreases were observed in wintertime high PM 2.5 concentrations. [ABSTRACT FROM AUTHOR]

Fe3O4/P(GMA-DVB)/PAMAM/Au microspheres are fabricated to research the catalytic performances to 4-nitrophenol. In the preparation process, Fe3O4 microspheres act as magnetic cores, PAMAM dendrimers growing up on the surface of P(GMA-DVB) polymer work as carriers, and Au nanoparticles serve as catalytic materials. The stability of the prepared microspheres is evaluated by successively catalytic experiments to measure the conversion of 4-nitrophenol, and catalytic efficiency can still maintain up to 78.7% after ten cycles. Moreover, the effects of major factors including the concentration of the prepared microspheres and the temperature of reaction system on the conversion of 4-nitrophenol are also investigated in detail. The manuscript reveals that 4-nitrophenol can be almost converted to 4-aminophenol within 7 min at 45 °C in the case of using 1.0 g/L Fe3O4/P(GMA-DVB)/PAMAM/Au microspheres. Such excellent catalytic properties are ascribed to the optimum structure of the prepared microspheres, which favors the sufficient contact between Au nanoparticles and 4-nitrophenol. The results and strategies exhibited here provide insight into the preparation of sophisticated structures of catalysts to treat wastewater. [ABSTRACT FROM AUTHOR]

Abstract Crop residue burning has been proved to have negative impacts on regional atmospheric environment. In this study, an evidence-based statistical modeling framework was established to quantify potential impacts of crop residue burning in the North China Plain (NCP) on summertime tropospheric ozone increase over East Asia during 2004–2016. To assess the intensity of crop residue burning, fire occurrence counts derived from the MODerate-resolution Imaging Spectroradiometer onboard the Terra and Aqua satellites were used as a proxy. Additionally, another six factors were employed as potent explanatory variables. Maximum covariance analysis was first applied to decouple spatiotemporal interactions between tropospheric ozone and each explanatory variable. Based on the decoupled modes, multivariate linear regression (MLR) and artificial neural network (ANN) were used to establish statistical relationships between tropospheric ozone and contributing factors, respectively. The results indicate that the ANN-based modeling scheme enables to approximate the observed tropospheric ozone variations better than MLR. Further investigations reveal that the summertime crop residue burning in the NCP is the predominant factor contributing to the observed additive tropospheric ozone increases over East Asia, yielding extra 8% tropospheric ozone elevation on average in June. Moreover, UV radiation and wind also played critical roles in modulating the observed tropospheric ozone variations therein. In general, the critical role of crop residue burning over the NCP in modulating summertime tropospheric ozone increase over East Asia have been well demonstrated based on the proposed evidenced-based modeling framework. Highlights • A novel statistical modeling framework was established to quantify tropospheric ozone response. • Associations between crop residue burning in the NCP and tropospheric ozone increase over East Asia were examined. • Crop residue burning in the NCP could result in extra 8% tropospheric ozone increase over East Asia in June. [ABSTRACT FROM AUTHOR]

Abstract The dimension of polyaniline (PANI) is effectively tuned by changing the end groups of additive surfactants. PANI fiberboards, dendrites, and rods are separately obtained through the guidance of micelle soft templates formed by the corresponding surfactants, i.e., sodium dodecyl sulfonate (SDS), sodium lauryl sulfonate (SLS), and sodium dodecyl benzene sulfonate (SDBS). Detailed mechanistic studies reveal that PANI structures are fabricated from a bottom-up self-assembly process where one-dimensional (1D) nanostructures are aggregated into higher order architectures. Electrochemical properties of these PANI nanostructures are examined in details, and exhibit morphological dependence. The PANI rods having high specific surface area and rough surface favor more ions enter into their body contact with active sites. As a consequence, they have higher specific capacitance (192 F g−1) than fiberboards (55 F g−1) and dendrites (64 F g−1) at 3.0 A g−1. Varying the substituent of additive molecules is in a position to alter the dimension of PANI that plays a decisive role in resulting electrochemical performances. This strategy may control the dimension and the properties of other conducting polymers for future applications. Graphical abstract Image Highlights • The dimension of PANI was effectively tuned by varying the end groups of additive surfactants. • PANI fiberboards, dendrites, and rods exhibited morphology dependent electrochemical properties. • PANI rods exhibited higher specific capacitance (192 F g−1) than fiberboards (55 F g−1) and dendrites (64 F g−1) at 3.0 A g−1. [ABSTRACT FROM AUTHOR]

[Display omitted] In recent years, electromagnetic pollution has become more and more serious, and there is an urgent need for microwave absorbing materials with superior performance. Prussian blue analogue (PBA) is a metal organic framework material with the advantages of diverse morphology and tunable composition. Therefore, PBA has attracted a lot of attention in the field of microwave absorption. In this work, PBA was coated on the surface of carbon composites by hydrothermal method, and then PPy was compounded on its surface after carbonization treatment to construct hierarchical core–shell CoC@CoFe/C@PPy fibers. The fibers have Co-doped C composites as the core and CoFe/C decorated with PPy as the shell. This unique hierarchical structure and various microwave absorption mechanisms are described in detail. The microwave absorption performance is optimized by adjusting the filling of the sample. The best microwave absorption performances are achieved at 25 wt% filling of CoC@CoFe/C@PPy. At a thickness of just 1.69 mm, CoC@CoFe/C@PPy fiebrs have a minimum reflection loss (RL min) of −64.32 dB. When the thickness is 1.88 mm, CoC@CoFe/C@PPy achieves a maximum effective absorption bandwidth (EAB max) of 5.38 GHz. The results indicate that the CoC@CoFe/C@PPy composite fibers have a great potential in the field of microwave absorption. [ABSTRACT FROM AUTHOR]

An efficient stereoselective route for the preparation of six stereoisomers of tert-butyl ((1 R , 2 S , 5 S )-2-amino-5-(dimethylcarbamoyl)cyclohexyl)carbamate 1 starting from simple 3-cyclohexene-1-carboxylic acid has been described. Stereochemistry of the title compounds was controlled at C2 center by Mitsunobu reaction and at C5 via a base-catalyzed epimerization. Only a limited usage of column chromatography has provided a direct and scalable route for the six stereoisomers. [ABSTRACT FROM AUTHOR]

At present, the development of electromagnetic wave absorption (EWA) materials is of great significance with the rapid development of electronic products. Based on the adjustable mechanical and electromagnetic properties of epoxy (EP)-based composite materials, research in the field of EWA has been continuously expanded. This review summarized recent developments of EP-based composites for their applications in EWA and classified composite materials according to the coating order and mixing ratio. In addition, the mechanisms of EWA were also introduced, including dielectric loss and magnetic loss. Finally, current challenges and opportunities for the development of EP-based EWA materials were proposed and the future development trend was pointed out. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) FeO/poly( N-isopropylacrylamide-methacrylic acid- N,N′ -methylenebisacrylamide)(FeO/P(NIPAM-MAA-MBA)) peapod-like nanochains have been successfully synthesized by magnetic field-induced precipitation polymerization. FeO microspheres modified with vinyl groups can be arranged with the direction of the external magnetic field in a line and linked permanently via P(NIPAM-MAA-MBA) coating during precipitation polymerization. The properties of 1D FeO/P(NIPAM-MAA-MBA) were characterized by transmission electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), vibrating sample magnetometry, X-ray photoelectron spectroscopy, and UV-Vis spectrophotometer. Magnetic measurement revealed that these 1D peapod-like nanochains showed highly magnetic sensitivity. The thermal- and pH- response of 1D magnetic FeO/P(NIPAM-MAA-MBA) nanochains was investigated by the temperature/pH dependence of hydrodynamic radius of FeO/P(NIPAM-MAA-MBA) microspheres. The release behavior of phenolphthalein from 1D magnetic FeO/P(NIPAM-MAA-MBA) nanochains could be effectively controlled by changing the temperature/pH values. [ABSTRACT FROM AUTHOR]

Gas sensors are essential for detecting toxic gases that can harm social life or industrial production. Traditional metal oxide semiconductor (MOS)-based sensors suffer from shortcomings such as high operating temperature and slow response time, which limits their detection capabilities. Thus, there is a need to improve their performance. One useful technique is noble metal functionalization, which can effectively enhance the response/recovery time, sensitivity and selectivity, sensing response, and optimum operating temperature of MOS gas sensors. Among the noble metals, Au NPs are considered a promising material for forming composite sensing materials to achieve better sensing performance. This paper aims to review and discuss the recent research on Au-decorated MOS-based sensors, including Au/n-type MOS-based sensors, Au/p-type MOS-based sensors, Au/MOS/carbon composite materials, and Au/MOS/perovskite composite materials. The sensing mechanism of Au-functionalized MOS-based materials will also be examined. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe3O4@TiO2 core–shell structured nanocomposites have been successfully synthesized by mixed-solvent with solvothermal method. [•] The morphology of Fe3O4@TiO2 nanochains can be controlled by the amount of ammonia. [•] The thickness of shell can be tuned by the amount of TBOT. [•] These Fe3O4@TiO2 nanocomposites exhibited high degree of crystallinity and excellent magnetic properties at room temperature. [Copyright &y& Elsevier]

Fe3O4 nanoparticles were prepared by solvothermal reaction, and structure-tailored Fe3O4/poly(glycidyl methacrylate-ethyleneglycol dimethacrylate- N-vinylcarbazole) (FeO/P(GMA-EGDMA-NVCz)) core-shell microspheres were achieved by distillation-precipitation polymerization of GMA, EGDMA, and NVCz in the presence of Fe3O4 nanoparticles. The properties of Fe3O4/P(GMA-EGDMA-NVCz) microspheres were characterized by transmission electron microscopy(TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and fluorescence spectroscopy. The results showed that the size of Fe3O4/P(GMA-EGDMA-NVCz) core-shell microspheres could be controlled to 930-470 nm by adjusting the amount of shell monomers, corresponding magnetic content of 45-82 wt%, and saturation magnetization of 32-63 emu/g. Moreover, the intensity of the fluorescence increased considerably with the decrease of shell thickness and the increase of NVCz concentration in the monomer mixture. [ABSTRACT FROM AUTHOR]

Tetraamido-oxacalix[4]arene derivatives have been synthesized via the reactions of tetraamino-oxacalix[4]arene with excess butyryl chloride, octanoyl chloride, benzoyl chloride and p-toluenesulfonyl chloride, respectively. 1H NMR results suggest that these oxacalix[4]arene derivatives preferentially adopt the 1,3-alternate (saddle-like) conformation in solution, which were also the case in the solid state as demonstrated by single crystal X-ray analysis. A dimerized slipped capsule could be formed by tetra-butyramido-oxacalix[4]arene in the solid state via intermolecular hydrogen bond interactions under the assistance of two encapsulated methanol molecules. On the other hand, a molecular cavity was formed by tetra- p-toluenesulfonamido-oxacalix[4]arene which can encapsulate a solvent molecule of ethyl acetate. [ABSTRACT FROM AUTHOR]

One-dimensional (ID) magnetic thermosensitive FeO/poly( N-isopropylacrylamide- N, N′-methylenebisacrylamide) (P(NIPAM-MBA)) peapod-like nanochains have been successfully synthesized by magnetic-field-induced precipitation polymerization using FeO as building blocks and P(NIPAM-MBA) as linker. FeO microspheres can be arranged with the direction of an external magnetic field in a line via the dipolar interaction between FeO microspheres and linked permanently via P(NIPAM-MBA) coating during precipitation polymerization. 1D magnetic FeO/P(NIPAM-MBA) peapod-like nanochains can be oriented and aligned along the direction of the external magnetic field. More interestingly, FeO microspheres in each peapod were regularly arranged in a line and periodically separated through the P(NIPAM-MBA) layers with a visible interparticle spacing. [ABSTRACT FROM AUTHOR]

Highly monodisperse P(Glycidyl methacrylate-Styrene) (P(GMA-St)) microspheres with spherical shape and smooth surface were prepared via batch dispersion copolymerization of GMA and St in ethanol medium, using 2,2′-azobisisobutyronitrile (AIBN) as initiator and polyvinylpyrrolidone (PVP) as stabilizer, respectively. The effects of various polymerization parameters such as St/GMA ratio and total monomer concentration on the morphology, particle size and size distribution were investigated. It was found that P(GMA-St) microspheres could be obtained with a size range of 2 to 9 µm by changing the solubility parameter of reaction mixture. St/GMA ratio had an important effect on the particle size and size distribution, and increasing the relative percentage of styrene in the mixture lead to an increase in particle size and a decrease in the molecular weight of copolymer when the St/GMA ratio was not more than 1. Monodisperse microspheres were obtained when the total monomers loading ranged from 10 to 25 wt%. Inner structure was observed by optical microscopy and a reasonable formation mechanism of P(GMA-St) was proposed. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional (1D) magnetic Fe3O4/P(GMA–DVB) peapod-like nanochains have been successfully synthesized by magnetic-field-induced precipitation polymerization using Fe3O4 as building blocks and P(GMA–DVB) as linker. The Fe3O4 microspheres without surface modification can be arranged with the direction of the external magnetic field in a line via the dipolar interaction between Fe3O4 microspheres and linked permanently via P(GMA–DVB) coating during precipitation polymerization. The length of peapod-like nanochains can be controlled by magnetic field intensity, and the thickness of polymer shell can be tuned by the amount of monomers. Magnetic measurement revealed that these 1D peapod-like nanochains showed highly magnetic sensitivity. In the presence of magnetic field, 1D magnetic Fe3O4/P(GMA–DVB) peapod-like nanochains can be oriented and aligned along the direction of external magnetic field. [Copyright &y& Elsevier]

Abstract: A magnetically separable Fe3O4–NH2–Pd (0) catalyst was easily synthesized by immobilizing Pd nanoparticles on the surface of magnetic Fe3O4–NH2 microspheres. It was found that the combination of Fe3O4 and triethylene tetramine (TETA) could give rise to structurally stable catalytic sites. Furthermore, the high-magnetization Fe3O4–NH2–Pd(0) catalyst can be recovered by magnet and reused for six runs for Heck reaction without significant loss in catalytic activity. [Copyright &y& Elsevier]

Abstract: TaC nanopowders were synthesized by a liquid precursor route. The synthesis procedures include (1) preparation of tantalum ethylate solution by sufficient mixing TaCl5 powders with ethanol, (2) adding activated carbon nanopowders to the solution, (3) dispersing activated carbon nanopowders in the solution evenly to form a liquid precursor by an ultrasonic equipment, (4) brushing the liquid precursor on an alumina crucible and blowing the liquid precursor to dry, (5) heat treatment in a graphitization furnace in a vacuum, and (6) brushing the alumina crucible to obtain products. X-ray diffraction patterns indicated that the products were cubic TaC. The formation temperature (1300°C) of TaC in this process is lower than that (1700°C) in the conventional method. The reaction time of forming TaC in this process is half an hour. The observed size of TaC powders by TEM was smaller than 50nm. The specific surface area of the powders by a surface area analyzer was 28.399m2/g. [ABSTRACT FROM AUTHOR]

Abstract: ortho-Linked oxacalix[n]arene[n]hetarenes (n=2, 3) were prepared by one-step cyclooligomerization of catechol and meta-dichlorinated nitrogen containing heterocycles or via a two-step reaction process. Solid state structure of the ortho-linked oxacalix[n]arene[n]hetarenes (n=2, 3) has been determined by X-ray crystallography. 1,3-Alternate and 1,3,5-alternate conformations were found for ortho-linked oxacalix[2]arene[2]pyrazine (1) and oxacalix[3]arene[3]pyrazine (2), respectively. However, a core conformation with C 3 symmetry was found for ortho-linked oxacalix[3]arene[3]pyrimidine (4), which is completely different from that of its isomer, compound 2. [Copyright &y& Elsevier]

With the seriously environmental pollution, photocatalytic technology has been extensively studied for ensuring the continuous development of society. As a type of appealing semiconductor, bismuth-based materials have become a research hotspot in the field of photocatalysis due to their unique electronic structure, appropriate bandgap energy, high light quantum and outstanding electronic transmission efficiency. However, the separation and recovery of photocatalyst from reaction systems is difficult. The most promising strategy to facilitate separation process is to introduce a magnetic component. This review has mainly involved a classification, current challenges and prospects on the recent progress in fabrication of magnetic bismuth-based photocatalytic materials, as well as the list of their degrade object, dosage, initial concentration and reaction time. [ABSTRACT FROM AUTHOR]

The parts of engineering machinery quickly generate rusty oxides in the working process, which seriously affects their service life and safety. How to remove oxides efficiently without damaging the surface of the matrix is a crucial problem. This paper analyzes the critical laser parameters that affect the distribution of material temperature field, which determines the ablation depth of different oxides, by using the central composite experimental design method and taking the surface-ablation depth of Fe2O3 and Fe3O4 before and after laser cleaning as response variables to establish the prediction model of single removal volume with the help of Comsol Multiphysics software. The results show a positive correlation between ablation depth and peak power density and a negative correlation with scanning speed. In this process, the experimental results show that the prediction model is natural and effective. A flow chart of laser stepwise cleaning of layered corroded oxides can provide theoretical guidance for the laser cleaning of engineering machinery. [ABSTRACT FROM AUTHOR]

• First long-term gap-free aerosol type grids were retrieved in China. • A 21-year daily 1-km resolution fine mode fraction dataset in China was generated. • Aerosol variations in China were resolved with long-term aerosol-type grids. • Haze reduction was confirmed by declining trends in anthropogenic aerosols. Spatially contiguous aerosol type grids were rarely available for air quality management in the past. To bridge the gap, we developed an integrated remote sensing and big data analytics framework to generate spatially gap-free aerosol type grids between 2000 and 2020 in China. The effect of emission control via environmental management on haze reduction was fully realized for the first time with the aid of satellite-based gap-free aerosol type data. Daily gap-free aerosol fine mode fraction (FMF) data were first derived via a data-driven regression model based on remote sensing big data. According to empirically determined FMF probability distributions over regions with typical emission sources, aerosols in China were classified into eight major types, including typical/atypical/mixed anthropogenic aerosols, typical/atypical/mixed dust, and typical mixed and multiple modes. The results indicated that the gridded FMF estimates derived in this study agreed well with FMF retrievals from AERONET, with correlation coefficient of 0.81 and root mean square error of 0.13. The long-term variations in major aerosol types showed that in China the territory covered by typical anthropogenic aerosols was reduced from 21.38% to 11.76% over the past two decades, while dust aerosols decreased from 6.99% to 2.15%. The declining trend in anthropogenic aerosols could be attributed to reduced coal consumption and/or favorable dispersion conditions, whereas decreasing dust aerosols were largely associated with increased vegetation cover and/or weakened wind speed in the west. Overall, such advancements provide fresh evidence to improve our understanding of the emission control effect on haze pollution variations in China. [ABSTRACT FROM AUTHOR]

With the advancement of wireless communication and electronic equipment, microwave absorption materials (MAMs) have more and more broad applications in related fields. Ti 3 C 2 T x -MXene with unique two-dimensional structure and excellent dielectric properties is often used as a precursor of nano-TiO 2 , which is a potential MAMs. Carbon nanofibers, as a one-dimensional material, have great electrical conductivity and can form interconnected three-dimensional conductive networks. In this study, Ti 3 C 2 T x -MXene was prepared by in-situ HF etching method, and further combined with the benefits of Co, Ce metals, and carbon nanofibers. Co/CeO 2 /TiO 2 /CNFs were prepared via a facile technique for electromagnetic microwave (EM) absorption, exhibiting excellent EM absorption performance due to the synergistic effects of dielectric and magnetic properties. The minimum reflection loss (RL min) and effective absorption bandwidth (EAB) reache −63.35 dB (11.2 GHz) and 3.6 GHz (9.5–13.1 GHz), with a thickness of only 2.35 mm and a filling rate of 30 wt%, while the maximum EAB reaches 5.4 GHz (12.4–17.8 GHz) with a thickness of 1.82 mm, covering nearly the entire Ku band. By offering a novel strategy to the creation of brand-new, high-performance MAMs based on 1D carbon nanofibers with dielectric/magnetic synergy, this work is believed to support the development of upcoming MAMs. [ABSTRACT FROM AUTHOR]

Polyurea elastomers exhibit superior mechanical properties due to their unique molecular structure, including significant tensile strength, elongation at break, and efficient energy absorption. Many studies have shown that polyurea elastomers can effectively reduce structural damage caused by blast loads, thus attracting widespread attention in the field of blast protection. This review presents a comprehensive analysis of the formulation optimization, energy absorption mechanism and the close relationship between microstructure and macroscopic properties of polyurea elastomers. Additionally, recent research advances in the blast resistance of sprayed polyurea elastomers in various protective structures are summarized. Finally, this review summarizes the current challenges in polyurea elastomer research and provides a forward-looking perspective on its future development. Future research should prioritize the design of formulations and material optimization to systematically study the factors influencing the protective performance of polyurea composite structures. It should also explore the application of advanced technologies in polyurea research to investigate the protection mechanisms at the microlevel. [ABSTRACT FROM AUTHOR]

A better knowledge of surface ozone variations and the relevant influential factors is of great significance for controlling frequent ozone pollution events. In this study, we first examined the primary variation patterns of surface ozone in space and time across China via a clustering analysis on the basis of daily maximum 8h average surface ozone (MDA8) between 2015 and 2018. Statistical models were then established between MDA8 and a set of influential factors to pinpoint dominant factors contributing to regional MDA8 variations. The clustering results revealed four typical variation patterns of MDA8 in China given distinct pollution levels, seasonality, and long-term trends. Statistical modeling results indicated that the seasonal variability of MDA8 was closely associated with UV radiation and meteorological factors like boundary layer height, temperature and relative humidity. In contrast, the long-term trends of MDA8 were largely linked to ozone precursors and meteorological variables including temperature, relative humidity, and total cloud cover. Moreover, the phenomenal increasing trends of MDA8 in North China were found to be statistically associated with the depletion of nitrogen dioxide (NO 2) and carbon monoxide (CO). Specifically, substantial increases in volatile organic compounds (VOCs) along with depletions in NO 2 and CO significantly boosted the photochemical ozone formation chain process in a VOC-limited regime like the North China plain. Overall, the inferred linkage in this study provides evidence and clues to help control increasing ozone pollution events in North China. • Surface ozone in China exhibited four distinct clustering patterns. • Ozone variability was modulated by diverse influential factors at distinct time scales. • Seasonality of surface ozone was regulated by UV radiation and temperature. • Increase in VOCs boosted the ozone photochemical production in North China. [ABSTRACT FROM AUTHOR]

• MnO 2 was designed as flower-like structure to obtain a larger surface area. • BiOBr and Bi metals were combined with MnO 2 to construct a heterojunction. • The magnetic core facilitated the recycling of the photocatalyst. • The core-shell structure can generate synergistic effects of different components. • Composite materials exhibited excellent dyes degradation capabilities. The flower-like Fe 3 O 4 /SiO 2 /MnO 2 /BiOBr-Bi magnetic composite photocatalyst was prepared in this work. The combination of BiOBr and Bi metal with flower-like MnO 2 constituted a heterojunction structure, which increased the specific surface area of the photocatalyst and promoted the separation of photo-generated carriers, resulting in the enhanced catalytic performance. The morphologies and the compositions of the photocatalyst were characterized in detail. Under simulated light, the degradation of organic dye methylene blue (MB) was used to research the photocatalytic activity. In the case of 15 mg photocatalyst, it was found that the photocatalytic degradation efficiency to the MB solution was 95.23% within 150 min. Moreover, the degradation rate of MB could still reach 81.11% after four cycles. The design of flower-like composites with magnetic core-shell structure provided a new method for fabricating photocatalysts having excellent catalytic performance and cyclic stability. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) microwave absorbers have attracted wide attention in the field of microwave absorption (MA) because of the significant anisotropy and great dielectric attenuation of 1D architecture. In this work, the novel 1D flower-like yolk-shell Fe 3 O 4 @SiO 2 @NiO (FSN) nanochains have been fabricated through a modified Stöber and a simple hydrothermal method. The unique 1D flower-like yolk-shell architectures have large surfaces, multiple interfaces and void spaces. Benefitting from these advantages, the FSN nanochains showed excellent MA properties. Compared with the sample loaded with 10 wt% 1D flower-like yolk-shell FSN nanochains, the sample loaded with 30 wt% showed strong MA performance with a minimum reflection loss (RL) value of −54.28 dB (12.9 GHz) and an effective absorption bandwidth of 4.0 GHz (11.05–15.05 GHz) at the thickness of 2.54 mm. The 1D flower-like yolk-shell FSN nanochains with strong absorption, broad absorption bandwidth and thin layers, provided a new method for fabricating 1D MA materials and will become the promising candidates in the practical MA fields. • One-dimensional yolk-shell flower-like Fe 3 O 4 @SiO 2 @NiO nanochains were synthesized successfully. • The yolk-shell structure was obtained while the NiO nanosheets grew on Fe 3 O 4 @SiO 2 nanochains by the hydrothermal method. • The microwave absorption properties of Fe 3 O 4 @SiO 2 @NiO nanochains composites were elucidated in depth. • The strongest absorption of −54.28 dB and the effective absorption bandwidth of 4.0 GHz can be obtained. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) microwave absorbing materials (MAMs) can induce self-assembly of graphene into aerogels, which provides ideas for the preparation of new MAMs. In here, 3D flower-like Fe 3 O 4 @SiO 2 @MnO 2 @reduced graphene oxide (RGO) (FSMG) composite aerogels have been fabricated via hydrothermal method, in which 1D Fe 3 O 4 @SiO 2 (FS) nanochains and two-dimensional (2D) MnO 2 sheets form a nano-scale core-shell structure on the surface of the RGO nanosheets. The unique microstructure of aerogels greatly enhances the microwave absorption capability. Particularly, the addition of RGO regulates the complex permittivity and improves the impedance matching of 1D Fe 3 O 4 @SiO 2 @MnO 2 (FSM) nanochains. Results demonstrate that the well-designed 3D conductive networks with significant oxygen vacancy defects powerfully favor the electromagnetic wave (EMW) absorption. The as-prepared FSMG composite aerogels show efficient microwave absorption (MA) properties with the maximum effective absorption bandwidth (EAB) of 4.26 GHz (7.13–11.39 GHz) at the corresponding coating thickness of 3.2 mm, accompanied by the minimum reflection loss (RL min) of about −55.01 dB. This work indicates that the FSMG composite aerogels are excellent absorbers with wide bandwidth, strong absorption, thin thickness and light weight, which can become a hopeful candidate in the field of MA. Unlabelled Image • The novel lightweight composite aerogels of Fe 3 O 4 @SiO 2 @MnO 2 @RGO were fabricated successfully. • One-dimensional flower-like Fe 3 O 4 @SiO 2 @MnO 2 nanochains were uniformly anchored onto the surface of the RGO nanosheets. • The microwave absorption mechanism of Fe 3 O 4 @SiO 2 @MnO 2 @RGO composite aerogels was elucidated in depth. • The composite aerogels exhibit strong absorption (RL min = −55.01 dB at 7.78 GHz) and broad bandwidth (7.13–11.39 GHz). [ABSTRACT FROM AUTHOR]

Yolk-shell magnetic Fe 3 O 4 /P(MAA-MBAA)-PPy/Au/void/TiO 2 microspheres have been prepared as visible light active photocatalyst. In this structure, the Fe 3 O 4 /P(MAA-MBAA)-PPy core-shell support provides magnetic properties for the catalyst and a large number of binding sites for the Au nanoparticles. In addition, coupling TiO 2 with Au nanoparticles can extend the range of absorbable sunlight and enhance electron hole separation. The test of degrading rhodamine B (RhB) under simulated visible light was used to verify the photocatalytic activity of the photocatalyst. The results showed that the photocatalyst exhibited favorable catalytic properties within 90 min in the case of using 4 mg itself. The improved performances were ascribed to the unique yolk-shell structure, which on the one hand greatly improves the light utilization, on the other hand favors full contact of the dye because of the porous appearance of the outer shell. Furthermore, the existence of magnetic core was beneficial to the recycling of the photocatalyst. And the recycling results demonstrated that the catalyst efficiency was maintained at 70.2% even after six recycling experiments. This work not only displays a new material for the degradation of organic dyes, but also provides a new approach for the synthesis of yolk-shell structure photocatalysts. A magnetic recyclable Fe 3 O 4 /P(MAA-MBAA)-PPy/Au/void/TiO 2 photocatalyst with yolk-shell structure is synthesized and has excellent catalytic properties. Image 1 • Two-step Ostwald ripening method was used to prepare hollow yolk-shell catalyst. • The magnetic polymer core was first used to anchor the Au NPs to couple with TiO 2. • The magnetic core facilitates the recycling of the photocatalyst. • The yolk shell structure can increase light capture and increase light utilization. • The SPR effect of Au NPs can extend the light absorption range of TiO 2 catalysts. [ABSTRACT FROM AUTHOR]

Developing a big data analytics framework for generating the Long-term Gap-free High-resolution Air Pollutant concentration dataset (abbreviated as LGHAP) is of great significance for environmental management and Earth system science analysis. By synergistically integrating multimodal aerosol data acquired from diverse sources via a tensor-flow-based data fusion method, a gap-free aerosol optical depth (AOD) dataset with a daily 1 km resolution covering the period of 2000–2020 in China was generated. Specifically, data gaps in daily AOD imageries from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Terra were reconstructed based on a set of AOD data tensors acquired from diverse satellites, numerical analysis, and in situ air quality measurements via integrative efforts of spatial pattern recognition for high-dimensional gridded image analysis and knowledge transfer in statistical data mining. To our knowledge, this is the first long-term gap-free high-resolution AOD dataset in China, from which spatially contiguous PM 2.5 and PM 10 concentrations were then estimated using an ensemble learning approach. Ground validation results indicate that the LGHAP AOD data are in good agreement with in situ AOD observations from the Aerosol Robotic Network (AERONET), with an R of 0.91 and RMSE equaling 0.21. Meanwhile, PM 2.5 and PM 10 estimations also agreed well with ground measurements, with R values of 0.95 and 0.94 and RMSEs of 12.03 and 19.56 µ g m -3 , respectively. The LGHAP provides a suite of long-term gap-free gridded maps with a high resolution to better examine aerosol changes in China over the past 2 decades, from which three major variation periods of haze pollution in China were revealed. Additionally, the proportion of the population exposed to unhealthy PM 2.5 increased from 50.60 % in 2000 to 63.81 % in 2014 across China, which was then reduced drastically to 34.03 % in 2020. Overall, the generated LGHAP dataset has great potential to trigger multidisciplinary applications in Earth observations, climate change, public health, ecosystem assessment, and environmental management. The daily resolution AOD, PM 2.5 , and PM 10 datasets are publicly available at https://doi.org/10.5281/zenodo.5652257 (Bai et al., 2021a), https://doi.org/10.5281/zenodo.5652265 (Bai et al., 2021b), and https://doi.org/10.5281/zenodo.5652263 (Bai et al., 2021c), respectively. Monthly and annual datasets can be acquired from https://doi.org/10.5281/zenodo.5655797 (Bai et al., 2021d) and https://doi.org/10.5281/zenodo.5655807 (Bai et al., 2021e), respectively. Python, MATLAB, R, and IDL codes are also provided to help users read and visualize these data. [ABSTRACT FROM AUTHOR]

A series of fluorescent molecules with 1,1-dimethylnaphthalene-2(1H)-one as the core were synthesized to overcome aggregation quenching and emit bright green fluorescence. The low molecular weight of these molecules led to them to smoothly pass through the cell membrane and penetrate deep into the nucleus to emit the corresponding fluorescence. Among them, NC-4-Br and NC-5-3O have good optical and in vitro properties and showed potential for use as fluorescent probes. [ABSTRACT FROM AUTHOR]

Summary Natural language inference (NLI) is a task to infer the relationship between the premise and hypothesis sentences, whose models have essential applications in the many natural language processing (NLP) fields, for example, machine reading comprehension and recognizing textual entailment. Due to the data‐driven programming paradigm, bugs inevitably occur in NLI models during the application process, which calls for novel automatic testing techniques to deal with NLI testing challenges. The main difficulty in achieving automatic testing for NLI models is the oracle problem; that is, it may be too expensive to label NLI model inputs manually and hence be too challenging to verify the correctness of model outputs. To tackle the oracle problem, this study proposes a novel automatic testing method hybrid mutation driven testing (HMT), which extends the mutation idea applied in other NLP domains successfully. Specifically, as there are two sets of sentences, that is, premise and hypothesis, to be mutated, we propose four mutation operators to achieve the hybrid mutation strategy, which mutate the premise and the hypothesis sentences jointly or individually. We assume that the mutation would not affect the outputs; that is, if the original and mutated outputs are inconsistent, inconsistency bugs could be detected without knowing the true labels. To evaluate our method HMT, we conduct experiments on two widely used datasets with two advanced models and generate more than 520,000 mutations by applying our mutation operators. Our experimental results show that (a) our method, HMT, can effectively generate mutated testing samples, (b) our method can effectively trigger the inconsistency bugs of the NLI models, and (c) all four mutation operators can independently trigger inconsistency bugs. [ABSTRACT FROM AUTHOR]

The Long-term Gap-free High-resolution Air Pollutants (LGHAP) concentration dataset generated in our previous study has provided spatially contiguous daily aerosol optical depth (AOD) and fine particulate matter (PM 2.5) concentrations at a 1 km grid resolution in China since 2000. This advancement empowered unprecedented assessments of regional aerosol variations and their influence on the environment, health, and climate over the past 20 years. However, there is a need to enhance such a high-quality AOD and PM 2.5 concentration dataset with new robust features and extended spatial coverage. In this study, we present version 2 of a global-scale LGHAP dataset (LGHAP v2), which was generated using improved big Earth data analytics via a seamless integration of versatile data science, pattern recognition, and machine learning methods. Specifically, multimodal AODs and air quality measurements acquired from relevant satellites, ground monitoring stations, and numerical models were harmonized by harnessing the capability of random-forest-based data-driven models. Subsequently, an improved tensor-flow-based AOD reconstruction algorithm was developed to weave the harmonized multisource AOD products together for filling data gaps in Multi-Angle Implementation of Atmospheric Correction (MAIAC) AOD retrievals from Terra. The results of the ablation experiments demonstrated better performance of the improved tensor-flow-based gap-filling method in terms of both convergence speed and data accuracy. Ground-based validation results indicated good data accuracy of this global gap-free AOD dataset, with a correlation coefficient (R) of 0.85 and a root mean square error (RMSE) of 0.14 compared to the worldwide AOD observations from the AErosol RObotic NETwork (AERONET), outperforming the purely reconstructed AODs (R = 0.83, RMSE = 0.15), but they were slightly worse than raw MAIAC AOD retrievals (R = 0.88, RMSE = 0.11). For PM 2.5 concentration mapping, a novel deep-learning approach, termed the SCene-Aware ensemble learning Graph ATtention network (SCAGAT), was hereby applied. While accounting for the scene representativeness of data-driven models across regions, the SCAGAT algorithm performed better during spatial extrapolation, largely reducing modeling biases over regions with limited and/or even absent in situ PM 2.5 concentration measurements. The validation results indicated that the gap-free PM 2.5 concentration estimates exhibit higher prediction accuracies, with an R of 0.95 and an RMSE of 5.7 µg m -3 , compared to PM 2.5 concentration measurements obtained from former holdout sites worldwide. Overall, while leveraging state-of-the-art methods in data science and artificial intelligence, a quality-enhanced LGHAP v2 dataset was generated through big Earth data analytics by cohesively weaving together multimodal AODs and air quality measurements from diverse sources. The gap-free, high-resolution, and global coverage merits render the LGHAP v2 dataset an invaluable database for advancing aerosol- and haze-related studies as well as triggering multidisciplinary applications for environmental management, health-risk assessment, and climate change attribution. All gap-free AOD and PM 2.5 concentration grids in the LGHAP v2 dataset, as well as the data user guide and relevant visualization codes, are publicly accessible at https://zenodo.org/communities/ecnu%5flghap (last access: 3 April 2024, Bai and Li, 2023a). [ABSTRACT FROM AUTHOR]

In this manuscript, hollow flower-like ferric oxide/manganese dioxide/trimanganese tetraoxide (Fe3O4/MnO2/Mn3O4) magnetically separable microspheres were prepared by combining a simple hydrothermal method and reduction method. As the MnO2 nanoflower working as precursor was partially reduced, Mn3O4 nanoparticles were in situ grown from the MnO2 nanosheet. The composite microspheres were characterized in detail by employing scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), vibration sample magnetometer (VSM) and UV–visible spectrophotometer (UV–vis). Under visible light conditions, the test for degrading rhodamine B (RhB) was used to verify the photocatalytic activity of the photocatalyst. The results showed that the efficiency of the Fe3O4/MnO2/Mn3O4 photocatalyst in visible light for 130 min is 94.5%. The catalytic activity of photocatalyst far exceeded that of the Fe3O4/MnO2 component, and after four cycles, the catalytic performance of the catalyst remained at 78.4%. The superior properties of the photocatalyst came from improved surface area, enhanced light absorption, and efficient charge separation of the MnO2/Mn3O4 heterostructure. This study constructed a green and efficient valence heterostructure composite that created a promising photocatalyst for degrading organic contaminants in aqueous environments. [ABSTRACT FROM AUTHOR]

In this paper, a simple route for palladium (Pd) nanoparticles attached to the surface of hollow magnetic Fe3O4/P (GMA‐DVB)‐polyethyleneimine (PEI) microspheres was established. Due to the large amount of imidogen groups and tertiary amine groups presenting in the PEI, Pd2+ ions could be anchored to the support by complexation with a polyfunctional organic ligand. Thereafter, a magnetic Pd catalyst having a high loading amount and good dispersibility was obtained by reducing Pd2+ ions. Afterwards, the prepared catalyst was characterized by TEM, SEM, FTIR, XRD, TGA, VSM, and UV–vis in detail. Ultimately, their catalytic activity was evaluated using the reduction of 4‐nitrophenol (4‐NP). Research showed that the Fe3O4/P (GMA‐DVB)‐PEI/Pd catalyst possessed high catalytic performances for the reduction of 4‐NP with a conversion rate of 98.43% within 540 s. Furthermore, the catalyst could be easily recovered and reused at least for nine successive cycles. [ABSTRACT FROM AUTHOR]

A strategy has been developed for the synthesis, characterization and catalysis of magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd core‐shell structure supported catalyst. The P(GMA‐EGDMA) polymer layer was coated on the surface of hollow magnetic Fe3O4 microspheres through the effect of KH570. The core‐shell magnetic Fe3O4/P(GMA‐EGDMA) modified by ‐NH2 could be grafted with HPG. Then, the hyperbranched glycidyl (HPG) with terminal ‐OH were modified by ‐COOH and adsorbed Pd nanoparticles. The hyperbranched polymer layer not only protected the Fe3O4 magnetic core from acid–base substrate corrosion, but also provided a number of functional groups as binding sites for Pd nanoparticles. The prepared catalyst was characterized by UV–vis, TEM, SEM, FTIR, TGA, ICP‐OES, BET, XRD, DLS and VSM. The catalytic tests showed that the magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd catalyst had excellent catalytic performance and retained 86% catalytic efficiency after 8 consecutive cycles. Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd microspheres are prepared with hyperbranched polymer layer, which can convent 4‐nitrophenol to 4‐aminophenol efficiently, and whose catalytic efficiency can still maintain up to 86% after eight cycles catalytic experiments. [ABSTRACT FROM AUTHOR]

The cover image is based on the Full Paper Preparation and characterization of magnetic hollow Fe3O4/P(GMA‐EGDMA)‐SO3H/Au‐PPy recyclable catalyst for catalytic reduction of 4‐nitrophenol by Na An et al., https://doi.org/10.1002/aoc.4739. [ABSTRACT FROM AUTHOR]

A highly effective and stable hollow Fe3O4/P(GMA‐EGDMA)‐SO3H/Au‐PPy catalyst was prepared. Monodisperse hollow Fe3O4 microspheres were synthesized using a hydrothermal method. As the catalyst support, magnetic hollow Fe3O4/P(GMA‐EGDMA) microspheres with core–shell structure were prepared by distillation precipitation polymerization. Then sulfonic acid groups (─SO3H) were introduced into the surface of the support by surface modification. Au3+ could be adsorbed by coordination with ─SO3H and underwent redox reactions with added pyrrole monomers. Finally, an Au–polypyrrole (PPy) layer was formed on the surface of the Fe3O4/P(GMA‐EGDMA)‐SO3H microspheres. The synthesized material was characterized using various techniques. Results indicated that the as‐prepared hollow Fe3O4/P(GMA‐EGDMA)‐SO3H/Au‐PPy catalyst had excellent catalytic activity and exhibited reusability for the reduction reaction of 4‐nitrophenol. In addition, the catalyst was reusable for at least ten successive cycles. A highly effective and stable hollow Fe3O4/P(GMA‐EGDMA)‐SO3H/Au‐PPy catalyst was prepared and characterized. The catalyst had excellent activity and exhibited reusability for the reduction reaction of 4‐nitrophenol. In addition, the catalyst was reusable for at least 10 successive cycles. [ABSTRACT FROM AUTHOR]