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Bright yellow-emitting long persistent luminescence from Mn^(2+)-activated strontium aluminate phosphor

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Journal of Rare Earths 2022年第7期40卷 1029-1036页

作者： Wenzhi Sun Tao Tan Jize cai Hongwu Zhang School of Chemistry and Materials Science Ludong UniversityYantai 264025China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

We developed bright yellow-emitting long persistent luminescence(LPL)materials Sr_(4)Al_(14)O_(25):Mn^(2+)and Sr_(4)Al_(14)O_(25):Mn^(2+),n(n=Zr^(4+),Ho^(3+),Er^(3+))by high temperature solid-state *** addition of Zr^(4+),Ho^(3+)and Er^(3+)can regulate trap distributions and improve energy storage ability of the *** LPL perfo rmance of SAO:Mn^(2+),Ho^(3+)is optimal,considering LPL intensity and duration *** LPL of SAO:Mn^(2+),Ho^(3+)can be observed for 3 h by naked eyes in dark after removing the excitation *** of LPL spectra are different from those of PL,because the two types of Mn^(2+)centers do not play equal parts in LPL and photoluminescence(PL).Trap depths of TL peaks centered at 354 K(peak 1)and 455 K(peak 2)are 0.60 and 0.72 eV,*** peak 1 at 354 K is the effective TL peak responsible for *** SAO:Mn^(2+),Ho^(3+),Mn^(2+)ions doped in Al^(3+)sites serve as emitting centers,and positively charged HoSr defects are the main effective trap ***,a feasible LPL mechanism of SAO:Mn^(2+),Ho^(3+)was proposed to clarify the generation process of LPL.

关键词： Long persistent phosphors Sr_(4)Al_(14)O_(25):Mn^(2+) Trap distributions Afterglow mechanism Rare earths

Mechanism of nitrogen loss driven by soil and water erosion in water source areas

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Journal of Forestry Research 2023年第6期34卷 1985-1995页

作者： Rongjia Wang Jianfeng Zhang Chunju cai Shufeng Wang State Key Laboratory of Subtropical Silviculture Zhejiang A&F UniversityHangzhou 311300People’s Republic of China Institute of Subtropical Forestry Chinese Academy of ForestryHangzhou 311400People’s Republic of China College of Forestry and Biotechnology Zhejiang A&F UniversityHangzhou 311300People’s Republic of China Sanya Research Base of the International Centre for Bamboo and Rattan Sanya 572000People’s Republic of China Zhejiang Provincial Key Laboratory of Forest Aromatic Plants-based Healthcare Functions Zhejiang A&F UniversityHangzhou 311300People’s Republic of China

nitrogen(n)present in drinking water as dissolved nitrates can directly affect people’s health,making it important to control n pollution in water source areas.n pollution caused by agricultural fertilizers can be controlled by reducing the amount of fertilizer applied,but pollution caused by soil and water erosion in hilly areas can only be controlled by conservation *** catchment area around Fushi Reservoir was selected as a test site and mechanisms of n loss from a vertical spatial perspective through field observations were *** main n losses occurred from June to September,accounting for 85.9-95.9%of the annual loss,with the losses in June and July accounting for 46.0%of the total,and in August and September for 41.9%.The n leakage from the water source area was effectively reduced by 38.2%through the optimization of the stand structure of the conservation *** well-structured forests for water conservation is crucial to ensure the security of drinking *** preliminary research lays the foundation for revealing then loss mechanisms in water source areas and improving the control of non-point source pollution in these areas.

关键词： Water source areas nitrogen loss non-point source pollution Water quality Surface runoff

An improved Isomap method for manifold learning

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International Journal of Intelligent Computing and Cybernetics 2017年第1期10卷 30-40页

作者： Taiguo Qu Zixing cai College of Computer Science and Technology Hengyang Normal UniversityHengyangChina Hunan Provincial Key Laboratory of Intelligent Information Processing and Application HengyangChina School of Information Science and Engineering Central South UniversityChangshaChina

Purpose-Isometric feature mapping(Isomap)is a very popular manifold learning method and is widely used in dimensionality reduction and data *** most time-consuming step in Isomap is to compute the shortest paths between all pairs of data points based on a neighbourhood *** classical Isomap(C-Isomap)is very slow,due to the use of Floyd’s algorithm to compute the shortest *** purpose of this paper is to speed up ***/methodology/approach-Through theoretical analysis,it is found that the neighbourhood graph in Isomap is *** this case,the Dijkstra’s algorithm with Fibonacci heap(Fib-Dij)is faster than Floyd’s *** this paper,an improved Isomap method based on Fib-Dij is *** using Fib-Dij to replace Floyd’s algorithm,an improved Isomap method is presented in this ***-Using the S-curve,the Swiss-roll,the Frey face database,the mixed national institute of standards and technology database of handwritten digits and a face image database,the performance of the proposed method is compared with C-Isomap,showing the consistency with C-Isomap and marked improvements in terms of the high *** also demonstrate that Fib-Dij reduces the computation time of the shortest paths from O(n3)to O(n2lgn).Research limitations/implications-Due to the limitations of the computer,the sizes of the data sets in this paper are all smaller than 3,***,researchers are encouraged to test the proposed algorithm on larger data ***/value-The new method based on Fib-Dij can greatly improve the speed of Isomap.

关键词： Dijkstra’s algorithm Fibonacci heap Floyd’s algorithm Isomap Manifold learning Shortest path Paper type Research paper

AnALYSIS On SMALL SCALE BRIDGInG In FIBROUS MOnOLITHIC CERAMICS

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Acta Mechanica Solida Sinica 1999年第3期12卷 227-238页

作者： Wu, ZJ cai, QH Tsing Hua Univ Dept Mech Engn Beijing 100084 Peoples R China

Based on shear lag model of interface between fiber and matrix, a new formula that relates the crack opening displacement and bridging force in fibrous monolithic ceramics was constructed under the framework of small scale bridging. This formula was applied to predict the fracture resistance or R-curve response of a three-point bending specimen made of fibrous monolithic ceramics. A parametric investigation on the influences of fiber volume fraction, fiber radius, characteristics of constituents, Bn's fracture toughness and specimen's geometry on the bridging forces and fracture resistance in Si3n4/Bn composite was carried out. The upper and lower limits of the R-curve of Si3n4/Bn in small scale bridging were derived. This research revealed the role played by the above parameters in the fracture toughness of fibrous monolithic ceramics.

关键词： fibrous monolithic ceramics fiber bridging R-curve fracture toughness

Giant magnetoresistance in antiferromagnetic Mn2Au-based tunnel junction

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Science China(Physics,Mechanics & Astronomy) 2020年第9期63卷 111-117页

作者： Xing-Tao Jia Xiao-Lin cai Yu Jia School of Physics and Electronic Information Engineering Henan Polytechnic UniversityJiaozuo 454000China International Laboratory for Quantum Functional Materials of Henan School of PhysicsZhengzhou UniversityZhengzhou 450001China Key Laboratory for Special Functional Materials of Ministry of Education School of Materials Science and EngineeringHenan UniversityKaifeng 475004China

Recent studies on the electrical switching of tetragonal antiferromagnet(AFM)via neél spin-orbit torque have paved the way for the economic use of antiferromagnetic *** most difficult obstacle that presently limits the application of antiferromagnetic materials in spintronics,especially in memory storage applications,could be the small and fragile magnetoresistance(MR)in the AFM-based *** this study,we investigated the spin transports in Mn2Au-based tunnel junctions based on the first-principle scattering *** MRs more than 1000%are predicted in some Fe/MgO/Ag/Mn2Au/Ta junctions that are about the same order as that in an MgO-based ferromagnetic tunnel junction with same barrier *** interplay of the spin filtering effect,the quantum well resonant states,and the interfacial resonant states could be responsible for the unusual giant and robust MRs observed in these Mn2Au-based junctions.

关键词： Mn2Au giant magnetoresistance tunnel junction

n-Heterocyclic carbene-catalyzed enantioselective(dynamic) kinetic resolutions and desymmetrizations

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Science China Chemistry 2024年第2期67卷 482-511页

作者： Yi Zhang Hui cai Xiuhai Gan Zhichao Jin national Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationGuizhou UniversityHuaxi DistrictGuiyang550025China

n-heterocyclic carbene-catalyzed enantioselective kinetic resolutions,dynamic kinetic resolutions,and desymmetrization reactions are systematically *** content is organized according to the activation modes involved i... 详细信息

关键词： n-heterocyclic carbene kinetic resolution dynamic kinetic resolution desymmetrization organocatalysis

Corrosion resistance and electrical conductivity of V/Ce conversion coating on magnesium alloy AZ31B

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International Journal of Minerals,Metallurgy and Materials 2023年第4期30卷 653-659页

作者： Jinxiao Yang Xudong Wang Yiren cai Xiuyu Yang Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China nAURA Technology Group Co. LtdBeijing 100176China

A V/Ce conversion coating was deposited in the surface of AZ31B magnesium alloy in a solution containing vanadate and cerium *** coating composition and morphology were *** conversion coating appears to consist of a thin and cracked coating with a scattering of spherical *** corrosion behavior of the substrate and conversion coating was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).Compared with AZ31B magnesium alloy,the corrosion current density of the conversion coating is decreased by two orders of *** total impedance of the V/Ce conversion coating rise to 1.6×10^(3)Ω·cm^(2)in contrast with2.2×10^(2)Ω·cm^(2)of the bare *** addition,the electrical conductivity of the coating was assessed by conductivity meter and Mott-Schottky *** results reveal a high dependence of the conductivity of the coating on the semiconductor properties of the phase compositions.

关键词： AZ31B magnesium alloy conversion coating conductivity corrosion resistance

Source identification, contamination status and health risk assessment of heavy metals from road dusts in Dhaka, Bangladesh

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Journal of Environmental Sciences 2022年第11期34卷 159-174页

作者： Aklima nargis Ahsan Habib Md nazrul Islam Kai Chen Md Shafiqul Islam Sarker A n M Al-Razee Wenbin Liu Guorui Liu Minggang cai Coastal and Ocean Management Institute&State Key laboratory of Marine Environmental Science Xiamen UniversityXiamen 361005China Department of Chemistry University of DhakaDhaka 1000Bangladesh Central Chemical Laboratory Department of Narcotics ControlMinistry of Home AffairsDhaka 1204Bangladesh Department of Analytical Chemistry&Environmental Science Training Institute for Chemical IndustriesPolashNarsingdi 1611Bangladesh State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

In this study, concentrations of Cr, Mn, ni, Cu, Zn, Cd and Pb were determined in road dusts collected from different locations in Dhaka to assess source, contamination status and health risk. Energy-dispersive X-ray fluorescence spectroscopy and energy-dispersive X-ray spectroscopy were used to determine Cr, Mn, ni, Cu, Zn, Cd and Pb and their mean concentrations were 162.27 ± 29.46, 721.18 ± 180.14, 35.65 ± 12.55, 104.56 ± 128.33, 515.32 ± 321.90,BDL, and 342.82 ± 591.20 mg/kg, respectively. Among the heavy metals, highest concentrations of Cu, Zn and Pb were found at urban sites-7(municipal waste dumping) and 8(medical waste incineration). Highest concentration of Cr followed by Cu and Zn was found at site-5(Tejgaon, urban). Principal component analysis revealed that anthropogenic activities are the potential sources for Cr, ni, Cu, Zn and Pb while earth crust for Mn. Pollution index and pollution load index results suggested that all the sites were contaminated and/or degraded by Cr, Cu, Zn and Pb except sites-9(urban), 10(sub-urban), 11(rural) while sites-7 and 8(urban) were extremely degraded. For noncarcinogenic health risk, hazard quotient values for dermal were higher compared to that of inhalation/ingestion. Though hazard index values were less than 1 at all the sites, these were at least one order of magnitude higher for children group than that of adult group, thus the children group may face more noncarcinogenic health risk at sites -7 and 8. Values of incremental lifetime cancer risk were from 10to 10showed no carcinogenic health risk by road dusts contaminated with the heavy metals.

关键词： Heavy metal Road dust Dhaka Principal component analysis Pollution status Health risk assessment

A Spatial-Temporal network Perspective for the Propagation Dynamics of Air Traffic Delays

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Engineering 2021年第4期7卷 452-464页

作者： Qing cai Sameer Alam Vu n.Duong School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

Intractable delays occur in air traffic due to the imbalance between ever-increasing air traffic demand and limited airspace *** air traffic is associated with complex air transport systems,delays can be magnified and propagated throughout these systems,resulting in the emergent behavior known as delay *** understanding of delay propagation dynamics is pertinent to modern air traffic *** this work,we present a complex network perspective of delay propagation ***,we model air traffic scenarios using spatial–temporal networks with airports as the *** establish the dynamic edges between the nodes,we develop a delay propagation method and apply it to a given set of air traffic *** on the constructed spatial-temporal networks,we suggest three metrics-magnitude,severity,and speed-to gauge delay propagation *** validate the effectiveness of the proposed method,we carry out case studies on domestic flights in the Southeastern Asia region(SAR)and the United *** demonstrate that the propagation magnitude in terms of the number of flights affected by delay propagation and the amount of propagated delays for the US traffic are respectively five and ten times those of the *** further reveal that the propagation speed for US traffic is eight times faster than that of the *** delay propagation dynamics reveal that about six hub airports in the SAR have significant propagated delays,while the situation in the United States is considerably worse,with a corresponding number of around *** work provides a potent tool for tracing the evolution of air traffic delays.

关键词： Air traffic Transport systems Delay propagation dynamics Spatial–temporal networks