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Science China(Technological Sciences) 2022年第2期65卷 481-489页

作者： LEI SaiLing WANG LiMing wang RongWu QIN XiaoHong YU JianYong Key Laboratory of Textile Science&Technology Ministry of EducationCollege of TextilesDonghua UniversityShanghai 201620China Innovation Center for Textile Science and Technology Donghua UniversityShanghai 201620China

Electrospun nanofibers are regarded as a promising candidate for filtration because of their prominent size effect.The precise control of nanofiber diameter is the key to the material’s outstanding filtration capability,but it remains a challenge.Herein,an electrohydrodynamic scaling model is established for the accurate prediction of fiber diameter based on the velocity of the whipping jet.In this model,the velocity reflects jet stretching and is tuned by adding salt.The theoretical predictions agree well with the experimental results.With the proposed diameter model,the filtration property of the membrane is significantly optimized by governing the fiber diameter.When the nanofiber is slenderized to 183 nm,an ultralight (0.521 g m;) membrane exhibits high filtration efficiency (99.93%) and low pressure drop (105.2 Pa) against ultrafine aerosol particles (≤0.26μm) under an airflow face velocity of 5.33 cm s^(-1).These findings demonstrate that the established surface charge-based diameter model provides an excellent platform to timely and accurately control the nanofiber diameter via the velocity of whipping jets for highefficiency air filtration.

关键词： electrospinning jet velocity fiber diameter filtration

Flexible, self-cleaning, and high-performance ceramic nanofiber-based moist-electric generator enabled by interfacial engineering

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Science China(Technological Sciences) 2022年第2期65卷 450-457页

作者： WANG LiMing FENG LanLan SUN Zhao Yang HE XinYang wang RongWu QIN XiaoHong YU JianYong Key Laboratory of Textile Science&Technology Ministry of EducationCollege of TextilesDonghua UniversityShanghai 201620China Innovation Center for Textile Science and Technology Donghua UniversityShanghai 201620China

Due to their long-term stability, even under extreme conditions, oxide ceramics have attracted significant attention in emerging fields like moist-electric generation. However, the inherent brittleness and low voltage output of oxide ceramic-based moistelectric generators(MEGs) limit their applications in wearable electronics. Herein, a facile strategy involving the combination of sol-gel electrospinning and calcination is used to fabricate flexible and freestanding Ti O_(2)/Zr O_(2)(TZ) composite nanofiber-based MEGs. The excellent flexibility of the TZ nanofiber membranes can be attributed to the suppression of their crystal structure transformation, dispersion of stress concentration, and reduction of crack propagation via interfacial engineering. The porous structure of the electrospun nanofiber membrane features an abundance of charged narrow channels for the diffusion of water molecules and generates a streaming potential. The optimal voltage output reached ~0.8 V, which is the highest value reported for an oxide ceramic-based MEG. Furthermore, the as-fabricated nanofiber-based MEG exhibits good self-cleaning capability to degrade organic pollutants under ultraviolet irradiation. By integrating mechanical flexibility, high performance, and a selfcleaning effect, this work presents a new idea for exploring diverse, efficient, and wearable oxide ceramic-based MEGs.

关键词： moist-electric generation ceramic nanofiber electrospinning flexible self-cleaning

Sharpness of the paired 660-km discontinuity beneath the Izu-Bonin area

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Earth and Planetary Physics 2020年第6期4卷 627-638页

作者： liming wang XiaoBo He Department of Marine Sciences Zhejiang UniversityZhoushan Zhejiang 316021China Marine Acoustics and Remote Sensing Laboratory Zhejiang Ocean UniversityZhoushan Zhejiang 316022China

The 660-km discontinuity that separates the Earth's upper and lower mantle has primarily been attributed to phase changes in olivine and other minerals.Resolving the sharpness is essential for predicting the composition of the mantle and for understanding its dynamic effects.In this study,we used S-to-P conversions from the 660-km interface,termed S660P,arriving in the P-wave coda from one earthquake in the Izu–Bonin subduction zone recorded by stations in Alaska.The S660P signals were of high quality,providing us an unprecedented opportunity to resolve the sharpness of the discontinuity.Our study demonstrated,based on the impedance contrast given by the IASP91 model,that the discontinuity has a transitional thickness of^5 km.In addition,we observed a prominent arrival right after the S660P,which was best explained by S-to-P conversions from a deeper discontinuity at a depth of^720 km with a transitional thickness of^20 km,termed S720P.The 720-km discontinuity is most likely the result of a phase transition from majoritic garnet to perovskite in the segregated oceanic crust(mainly the mid-oceanic ridge basalt composition)at the uppermost lower mantle beneath this area.The inferred phase changes are also consistent with predictions from mineral physics experiments.

关键词： 660-km discontinuity S-to-P conversions Izu-Bonin sharpness mid-oceanic ridge basalt

Stress and Strain in Perovskite/Silicon Tandem Solar Cells

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Nano-Micro Letters 2023年第4期15卷 272-276页

作者： Kong Liu Zhijie wang Shengchun Qu liming Ding Key Laboratory of Semiconductor Materials Science(CAS) Beijing Key Laboratory of Low Dimensional Semiconductor Materials and DevicesInstitute of SemiconductorsChinese Academy of SciencesBeijing 100083People’s Republic of China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049People’s Republic of China Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190People’s Republic of China

Tandem solar cells based on metal halide perovskites are advancing rapidly during last few years[1–17].The certified power conversion efficiency(PCE)for monolithic perovskite/silicon tandem solar cell reaches 32.5%[18].Since tandem solar cells contain more layers than single-junction solar cells,stress/strain control is an issue during fabrication and further practical operation.The stress can not only affect the stability of the perovskite layer but also change the optoelectronic properties of the films[19–23].

关键词： perovskite halide stability

Improved Mechanical Properties in Carbon Martensitic Steel Achieved by Continuous Carbon Gradient and Multilayered Structure

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Acta Metallurgica Sinica(English Letters) 2023年第12期36卷 2069-2078页

作者： Jian wang Jiantao Fan liming Fu Aidang Shan School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory of High Temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China

Increasing carbon content in martensite enhances the strength of carbon steel but reduces ductility and toughness.In this study,a multilayered carbon gradient steel was developed to overcome this trade-off by stacking high-carbon(1 wt%)and low-carbon(0.2 wt%)steel plates through preliminary diffusion and multi-pass hot rolling.The resulting microstructure showed a continuous gradient from high-carbon martensite to low-carbon martensite.After low-temperature tempering,the tempered samples exhibited hardness fluctuations along the normal direction,with a maximum value of approximately 700 HV or more in high-carbon regions and a lower value of 500 HV or less in low-carbon regions.Compared to low-carbon steel,the sample tempered at 200℃showed significant improvements in both strength and ductility,with 1880 MPa ultimate tensile strength and 4.7%uniform elongation.This larger uniform elongation than that of the plain low-carbon steel can be attributed to the greater strain hardening rate in high-carbon regions with a high carbon solid solution strengthening.Simultaneously,it is believed that more slip systems in high-carbon regions could be activated under the multiaxial stress around the layer interface,then showing a better ductility than that of the plain high-carbon steel.Additionally,the gradient structure between different regions effectively helped to avoid abrupt stress and deliver multiaxial stress at any location along the normal direction.The stepped path of the cracks under uniaxial tensile stress suggested a higher fracture toughness.

关键词： Carbon steel Multilayer Gradient Strength and ductility Multiaxial stress

Mineralization of the Lianhuashan Sn-polymetallic deposits associated with dynamic metamorphism:Constraints from cassiterite geochemistry and U-Pb geochronology

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Science China Earth Sciences 2023年第7期66卷 1664-1677页

作者： Jun wang liming wang Shuang YAN Yong MA Diankui XU CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China Geology Bureau for Nonferrous Metal of Guangdong Province Guangzhou 510080China Nonferrous Geological Exploration Institute of Guangdong Province Guangzhou 510080China Nonferrous Metal Geological Bureau of Guangdong Province 931 Battalion Shantou 515041China

The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the Tashan,Xianshuili,and Jiangxikeng.However,the metallogenic mechanism of these deposits remains hotly debated.In this paper,two types of cassiterites(Cst1 and Cst2)have been identified in the Xianshuili and Jiangxikeng Sn deposits,which are hosted in the biotite-mylonite and garnetcordierite-muscovite blastomylonite,respectively.The euhedral Cst1(0.50–1.8 mm)coexists with biotite,feldspar,and quartz.It is platy and zoned with a mosaic structure.The subhedral to anhedral Cst2(0.02–0.35 mm)coexists with metamorphic minerals such as garnet and cordierite,and it is characterized by well-developed porosity and has no zonation.In-situ U-Pb dating of the Cst1 and Cst2 yielded ages of 149.5±1.0 Ma(MSWD=1.6,n=45)and 125.1±2.3 Ma(MSWD=4.5,n=43),respectively.Cst1 is most likely to be related to the intermediate-felsic magmatism that formed Gaojiping Group,whereas Cst2 has relatively high Ta,Nb,Fe,and W contents with obvious rare earth tetragroup effect,and may have formed by the late Early Cretaceous dynamic metamorphism.Results presented here,when combined with regional geology and geochemistry,led us to suggest that the Mesozoic intermediate-felsic volcanic rocks in the LMB are significantly enriched in Sn and F,with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related Cst1.In the late Early Cretaceous period,due to the NW-dipping subduction of the paleo-Pacific plate,the intermediate-felsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization,migration,and precipitation in the regional ductile shear zones,and eventually generating Sn mineralization.We propose that areas beneath Xianshuili and Jiangxikeng have great potential for discovery of new Sn resources.Our findings likely offer practical importance to regional geological ore prospecting.

关键词： Lianhuashan metallogenic belt(LMB) Sn-polymetallic deposit Cassiterite U-Pb geohronology Dynamic metamorphism

In situ identification of active sites during electrocatalytic hydrogen evolution

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Nano Research 2023年第12期16卷 12910-12918页

作者： Dongge wang Juanxia Wu Liying Jiao liming Xie CAS Key Laboratory of Standardization and Measurement for Nanotechnology National Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China

The rational design of efficient,low cost,and durable catalysts is critical for the industrial applications of electrocatalytic hydrogen production.A key step towards the structure design of high-performance catalysts for hydrogen evolution reaction(HER)relies on the in situ identification of the catalytic active sites in the process of HER,which is of great challenge.In this review,we summarize the recent advances on the in situ investigation of the active sites on low dimensional catalysts for HER.We highlight the characterization techniques used for this purpose,including scanning electrochemical microscopy(SECM),scanning electrochemical cell microscopy(SECCM),electrochemical scanning tunneling microscopy(EC-STM),in situ liquid phase transmission electron microscopy(LP-TEM),and in situ spectroscopic tools.We conclude with an overview of the main technical limitations for the current approaches and give an outlook to future opportunities in this emerging field.

关键词： in situ hydrogen evolution reaction active sites electrocatalyst

Research of cycloaliphatic epoxy resin and silicone rubber composite insulator interface based on four-electrode system and temperature rise model

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High Voltage 2023年第3期8卷 560-569页

作者： Yunsong wang Yuhao Liu Hongwei Mei Min Xie liming wang Shenzhen International Graduate School(SIGS) Tsinghua UniversityShenzhenChina Research Institute of Tsinghua Pearl River DeltaGuangzhouChina

Interface degradation between mandrel and sheath can cause a decrease in insulation performance and mechanical strength of composite insulators.In this study,the interface ageing properties of cycloaliphatic epoxy resin and silicone rubber composite insulator were compared.A water diffusion test was adopted to simulate the composite insulator ageing in a hot and humid environment.A four-electrode system was built to detect leakage current at different locations(mandrel,sheath and interface),which is an important basis for evaluating insulator performance.The ageing degree of insulator could be quantitatively characterised by leakage current change.It was found that the infiltrated moisture had a great effect on insulation performance.Based on the water absorption test result,the interface performance of two insulators was mainly influenced by their sheath sealing quality.As an auxiliary evaluation method,temperature rise during the test was recorded using an infrared camera.The experiment results showed that interface degradation was the main factor for the insulation performance decrease of silicone rubber composite insulators.However,insulation level reduction of the cycloaliphatic epoxy resin was caused by the wet sheath.In addition,a model for temperature rise of cycloaliphatic epoxy resin insulators was proposed based on good correspondence between sheath material and insulation.The model incorporated multiple processes such as ageing and heating of insulators,and it can predict the early temperature rise well.

关键词： insulator composite interface

Wetting characteristics of the hydrophobic material surface through condensation

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High Voltage 2023年第1期8卷 31-37页

作者： Xiaohan Wu Bin Cao liming wang Chuyan Zhang Department of Tsinghua-Berkeley Shenzhen Institute(TBSI) Tsinghua UniversityShenzhenChina Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhenChina School of Information Engineering China University of Geosciences(Beijing)BeijingChina

Composite insulators are generally considered to have excellent anti-pollution flashover performance,but recently there has been a flashover accident on the indoor clean insulator in China,which is suspected to be related to the wetting of insulators through condensation.Therefore,this paper studied the water condensation on hydrophobic surfaces.The changes in the mass,length,and proportion of the water droplets on the hydrophobic surface during the wetting process were measured,and the influence of wetting degree on the flashover characteristics was studied.It was found that the insulator surface temperature lower than the dew point is a prerequisite for the wetting of the clean hydrophobic surface,and the wetting velocity increases with the electric field.The results could provide some reference for understanding the insulator flashover accidents.

关键词： surface characteristics flash

The dynamics of delayed models for interactive wild and sterile mosquito populations

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生物数学学报:英文版 2023年第5期16卷 137-164页

作者： Juan wang Peixia Yue liming Cai College of Mathematics and Statistics Xinyang Normal University Xinyang 464000P.R.China

The sterile insect technique(SIT)has been applied as an alternative method to reduce or eradicate mosquito-borne diseases.To explore the impact of the sterile mosquitoes on controlling the wild mosquito populations,in this paper,we further extend the work in[J.Li,New revised simple models for interactive wild and sterile mosquito populations and their dynamics,J.Biol.Dyn.11(S2)(2017)316-333]and formulate delayed models for interactive wild and sterile mosquitoes,which can depict wild mosquito population undergoing distinct stages of development during a lifetime.By performing mathematical analysis,the threshold dynamics of the proposed models are explored,respectively.In particular,Hopf bifurcation phenomena are observed as the delay T is varying.Numerical examples illustrateourfindings.

关键词： Sterile mosquito release control strategy time-delay stability Hopf bifurcation