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Pollution characteristics and quantitative source apportionment of heavy metals within a zinc smelting site by GIS-based PMF and APCS-MLR models

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Journal of Environmental Sciences 2024年第10期144卷 100-112页

作者： Huagang lv Zhihuang Lu Guangxuan Fu Sifang lv Jun Jiang Yi Xie Xinghua Luo Jiaqing Zeng Shengguo xue School of Metallurgy and Environment Central South UniversityChangsha 410083China Zhuzhou Qingshuitang Technology Co. Ltd.Zhuzhou 412000China New World Environment Protection Group of Hunan Changsha 410083China

The abandoned smelters present a substantial pollution threat to the nearby soil and *** this study,63 surface soil samples were collected from a zinc smelter to quantitatively describe the pollution characteristics,ecological risks,and source apportionment of heavy metal(loid)s(HMs).The results revealed that the average contents of Zn,Cd,Pb,As,and Hg were 0.4,12.2,3.3,5.3,and 12.7 times higher than the risk screening values of the construction sites,***,the smelter was accumulated heavily with Cd and Hg,and the contribution of Cd(0.38)and Hg(0.53)to ecological risk was 91.58%.ZZ3 and ZZ7 were the most polluted workshops,accounting for 25.7%and 35.0%of the pollution load and ecological risk,*** influence of soil parent materials on pollution was minor compared to various workshops within the *** with PMF,APCS-MLR and GIS analysis,four sources of HMs were identified:P1(25.5%)and A3(18.4%)were atmospheric deposition from the electric defogging workshop and surface runoff from the smelter;P2(32.7%)and A2(20.9%)were surface runoff of As-Pb foul acid;P3(14.5%)and A4(49.8%)were atmospheric deposition from the leach slag drying workshop;P4(27.3%)and A1(10.8%)were the smelting process of zinc *** paper described the distribution characteristics and specific sources of HMs in different process workshops,providing a new perspective for the precise remediation of the smelter by determining the priority control factors.

关键词： Smelter site Heavy metal(loid)s Source apportionment Positive matrix factorization Absolute principal component score-multiple linear regression

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Optical scattering imaging with sub-nanometer precision based on position-ultra-sensitive giant Lamb shift

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 96-105页

作者： Zeyang Liao Yu-wei Lu wei Li xue-Hua Wang State Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou 510275China Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong) Shenzhen 518045China

The Lamb shift of a quantum emitter in close proximity to a plasmonic nanostructure can be three or more orders of magnitude larger than that in the free space and is ultra-sensitive to the emitter position and *** demonstrate that this large Lamb shift can be sensitively observed from the scattering or absorption spectrum dip shift of the coupled system when the plasmonic nanoparticle or tip scans the *** these observations,we propose a scanning optical scattering imaging method based on the plasmonic-enhanced Lamb shift with achieves sub-nanometer *** method is based on the scattering or absorption spectrum of the plasmon-emitter coupling system,which is free of the fluorescence quenching problem and easier to implement in a plasmon-emitter coupling *** addition,our scheme works even if the quantum emitter is slightly below the dielectric surface,which can bring about broader applications,such as detecting atoms and molecules or quantum dots above or under a surface.

关键词： Lamb shift plasmon optical scattering imaging

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Additive-free synthesis of S-substituted isothioureas via visible-light-induced four-component reaction ofα-diazoesters,aryl isothiocyanates,amines and cyclic ethers

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Chinese Chemical Letters 2024年第2期35卷 415-419页

作者： Yufen lv Hongyu Ding Jinmao You wei wei Dong Yi Key Laboratory of Catalytic Conversion and Clean Energy in Universities of Shandong Province School of Chemistry and Chemical EngineeringQufu Normal UniversityQufu 273165China College of Chemistry and Chemical Engineering Shaoxing UniversityShaoxing 312000China School of Pharmacy Southwest Medical UniversityLuzhou 646000China

An additive-free and environmentally friendly strategy has been realized for the construction of S-substituted isothioureas through visible-light-induced multicomponent reaction starting fromα-diazoesters,aryl isothiocyanates,amines and cyclic *** methodology features simple operation,mild reaction conditions,favorable functional group tolerance,easily available starting materials and high efficiency.

关键词： Visible-light Additive-free Four-component reaction S-Substituted isothioureas

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A condition-based maintenance policy for reconfigurable multi-device systems

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Advances in Manufacturing 2024年第2期12卷 252-269页

作者： Shu-Lian Xie Feng xue wei-Min Zhang Jia-wei Zhu School of Mechanical Engineering Tongji UniversityShanghai201804People’s Republic of China

The exploration of component states for optimizing maintenance schedules in complex systems has garnered significant interest from ***,current literature usually overlooks the critical aspects of system flexibility and *** implementation of system reconfiguration can effectively mitigate system downtime and enhance production *** study proposes a dynamic condition-based maintenance policy considering reconfiguration for reconfigurable systems.A double-layer decision rule was constructed for the devices and *** achieve the best overall maintenance effect of the system,the remaining useful life probability distribution and recommended maintenance time of each device were used to optimize the concurrent maintenance time window of the devices and determine whether to reconfigure them.A comprehensive maintenance efficiency index was introduced that simultaneously considered the maintenance cost rate,reliability,and availability of the system to characterize the overall maintenance *** reconfiguration cost was included in the maintenance *** proposed policy was tested through numerical experiments and compared with different-level *** results show that the proposed policy can significantly reduce the downtime and maintenance costs and improve the overall system reliability and availability.

关键词： Condition-based maintenance(CBM) Reconfigurable system Remaining useful life Maintenance cost System reliability

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A brief review of tribological properties for black phosphorus

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Friction 2024年第5期12卷 823-844页

作者： Fanfan lv wei WANG Jinjin LI Yuan GAO Kuaishe WANG College of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing10084China

Black phosphorus (BP) is a new class of two-dimensional (2D) layered material, which shows the unanticipated characteristics in many aspects including electronics, transistors, sensors, energy storage, batteries, photocatalysis, and other applications due to its high charge carrier mobility, tunable direct bandgap, and unique in-plane anisotropic structure. In addition, BP has drawn tremendous attention in the field of tribology due to the low shear strength, the layered structure, and the weak connected force between the layers by van der Waals interaction. In recent years, many significant progresses have been made in experimental studies on BP materials as solid lubricants or lubrication additives. This work offers a review of researching regarding the tribological properties of BP. Moreover, the lubrication mechanisms of BP as the lubrication additive including the formation of the tribo-film, micro-bearing effect, and self-repair performance are also summarized. Finally, the current challenges and prospects of BP material as lubricant are proposed.

关键词： black phosphorus(BP) two-dimensional(2D)layered material lubrication additives tribological mechanisms

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Joint Sample Position Based Noise Filtering and Mean Shift Clustering for Imbalanced Classification Learning

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Tsinghua Science and Technology 2024年第1期29卷 216-231页

作者： Lilong Duan wei xue Jun Huang Xiao Zheng School of Computer Science and Technology Anhui University of TechnologyMaanshan 243032China Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China

The problem of imbalanced data classification learning has received much *** classification algorithms are susceptible to data skew to favor majority samples and ignore minority *** weighted minority oversampling technique(MWMOTE)is an effective approach to solve this problem,however,it may suffer from the shortcomings of inadequate noise filtering and synthesizing the same samples as the original minority *** this end,we propose an improved MWMOTE method named joint sample position based noise filtering and mean shift clustering(SPMSC)to solve these ***,in order to effectively eliminate the effect of noisy samples,SPMsC uses a new noise filtering mechanism to determine whether a minority sample is noisy or not based on its position and distribution relative to the majority *** that MWMOTE may generate duplicate samples,we then employ the mean shift algorithm to cluster minority samples to reduce synthetic replicate ***,data cleaning is performed on the processed data to further eliminate class *** on extensive benchmark datasets demonstrate the effectiveness of SPMsC compared with other sampling methods.

关键词： imbalanced data classification oversampling noise filtering clustering

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Aerosol-radiation interaction and its variation in North China within 2015–2019 period under continuous PM_(2.5)improvements

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Journal of Environmental Sciences 2024年第2期136卷 81-94页

作者： Zhe lv Xiaoqi Wang wei wei Huahua Bai Xiaoyu Liu Guohao Li Shuiyuan Cheng Department of Environmental Science and Engineering Beijing University of TechnologyBeijing 100124China Key Laboratory of Beijing on Regional Air Pollution Control Beijing 100124China Beijing Municipal Research Institute of Eco-Environmental Protection Beijing 100037China Beijing Key Laboratory of Urban Atmospheric Volatile Organic Compounds Pollution Control and Application Beijing 100037China

A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015–2019 ***-Chem simulations on 2017 showed that based on the six-city average,the aerosol load(PM_(2.5)concentrations)of 121.9,49.6,43.3,and 66.3μg/m^(3)in January,April,July,and October,mainly lowered the level of downward shortwave radiation by 38.9,24.0,59.1,and 24.4 W/m~2and reduced the boundary layer height by 79.9,40.8,87.4,and 31.0 m,via scattering and absorbing solar *** sensitivity of meteorological changes to identical aerosol loads varied in the order July>January>October and ***,the cooling and stabilizing effects of aerosols further led to increases in PM_(2.5),by23.0,3.4,4.6,and 7.3μg/m^(3)respectively in the four *** sensitivity of the effect of aerosols on PM_(2.5)was greatest in January rather than in July,contrary to the effect on ***,a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter,and between PM_(2.5)increases and aerosol loads in all *** the PM_(2.5)pollution improvements in this region,the aerosol radiative forcing was effectively *** should result in daily BLH increases of 10–24 m in fall and winter,and the estimates in Beijing agreed well with the corresponding results based on AMDAR ***,the reduction in aerosol radiation effects brought about daily PM_(2.5)decreases of 1.6-2.8μg/m^(3),accounting for 7.0%–17.7%in PM_(2.5)improvements.

关键词： Radiative forcing Aerosol PM_(2.5) Boundary layer height(BLH) North China

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Dynamic cooperations between lattice oxygen and oxygen vacancies for photocatalytic ethane dehydrogenation by a self-restoring LaVO_(4)catalyst

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Chinese Chemical Letters 2024年第3期35卷 171-176页

作者： Fen wei weichao xue Zhiyang Yu xue Feng Lu Sibo Wang wei Lin Xinchen Wang State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhou 350108China

Thermocatalytic nonoxidative ethane dehydrogenation(EDH)is a promising strategy for ethene production but suffers from intense energy consumption and poor catalyst durability;exploring technology that permits efficient EDH by solar energy remains a giant ***,we present that an oxygen vacancy(O_v)-rich LaVO_(4)(LaVO_(4)-O_v)catalyst is highly active and stable for photocatalytic EDH,through a dynamic lattice oxygen(O_(latt.))and O_(v)co-mediated *** by simulated sunlight at mild conditions,LaVO_(4)-O_(v)effectively dehydrogenates undiluted ethane to produce C_(2)H_(4)and CO with a conversion of 2.3%.By loading a small amount of Pt cocatalyst,the evolution and selectivity of C_(2)H_(4)are enhanced to 275μmol h^(-1)g^(-1)and 96.8%.Of note,LaVO_(4)-O_(v)appears nearly no carbon deposition after the *** isotope tracked reactions reveal that the consumed O_(latt.)recuperates by exposing the used catalyst with O_(2),thus establishing a dynamic cycle of O_(latt.)and achieving a facile catalyst regeneration to preserve its intrinsic *** refreshed LaVO_(4)-O_(v)exhibits superior reusability and delivers a turnover number of about *** O_(v)promotes photo absorption,boosts ethane adsorption/activation,and accelerates charge separation/transfer,thus improving the photocatalytic *** possible photocatalytic EDH mechanism is proposed,considering the key intermediates predicted by density functional theory(DFT)and monitored by in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).

关键词： Photocatalysis Ethane dehydrogenation Ethene LaVO_(4) Oxygen vacancy

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Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

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Chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： Jing lv Xu Chen Zi-Shuo Wu Ya-Hui Li wei Chen National Synchrotron Radiation Laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR *** plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich *** time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific *** quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is *** ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation *** origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen ***,the existence of a mobility gradient in the VB unit has been ***,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first *** indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

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Equilibrium Reinsurance Strategy and Mean Residual Life Function

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 758-777页

作者： Dan-ping LI lv CHEN Lin-yi QIAN wei WANG School of Statistics Key Laboratory of Advanced Theory and Application in Statistics and Data Science-MOEEast China Normal UniversityShanghai 200062China Academy of Statistics and Interdisciplinary Sciences Key Laboratory of Advanced Theory and Application in Statistics and Data Science-MOEEast China Normal UniversityShanghai 200062China School of Mathematics and Statistics Ningbo UniversityNingbo 315211China

In this paper,we analyze the relationship between the equilibrium reinsurance strategy and the tail of the distribution of the *** Mean Residual Life(MRL)has a close relationship with the tail of the distribution,we consider two classes of risk distributions,Decreasing Mean Residual Life(DMRL)and Increasing Mean Residual Life(IMRL)distributions,which can be used to classify light-tailed and heavy-tailed distributions,*** assume that the underlying risk process is modelled by the classical CramérLundberg model *** the mean-variance criterion,by solving the extended Hamilton-Jacobi-Bellman equation,we derive the equilibrium reinsurance strategy for the insurer and the reinsurer under DMRL and IMRL,***,we analyze how to choose the reinsurance premium to make the insurer and the reinsurer agree with the same reinsurance *** find that under the case of DMRL,if the distribution and the risk aversions satisfy certain conditions,the insurer and the reinsurer can adopt a reinsurance premium to agree on a reinsurance strategy,and under the case of IMRL,the insurer and the reinsurer can only agree with each other that the insurer do not purchase the reinsurance.

关键词： mean residual life excess-of-loss reinsurance insurer reinsurer stochastic control

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