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Crown ether-assisted room-temperature halide passivation for highefficiency PbS quantum dots enabling large-area and long-lifetime near-infrared QD-OLEDs

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Nano Research 2023年第5期16卷 7537-7544页

作者： Zhen Jia Haoyun Shao Jingyi xu Yu Dai juan Qiao Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China Laboratory for Flexible Electronics Technology Tsinghua UniversityBeijing 100084China

High-efficiency and low-cost near-infrared(NIR)emitting quantum dots(QDs)are highly desirable for next-generation intrinsically flexible NIR light *** passivation is commonly employed to passivate surface traps to obtain high-quality NIRemitting PbS QDs,but this procedure requires high temperature and inert *** we develop a facile roomtemperature halide passivation method for highly efficient NIR-emitting PbS QDs by employing crown ethers as a unique auxiliary *** and theoretical investigations reveal that the formation of K^(+)-crown ethers complex effectively facilitates the dissociation of KCl in toluene and releases more Cl^(−)ions for extraordinary halide passivation at room temperature and in the air,thus improving the photoluminescence quantum yield from 24%to 35%in solution and further to 44%in blend *** well-passivated PbS QD films are integrated with red organic light-emitting diodes(OLEDs)and the resulting QDOLEDs exhibit high-performance NIR emission centered at 887 nm,a high external quantum efficiency of 5.2%at a radiance of 10 W·sr^(−1)·m^(−2),superior operational stability with long lifetime T90 of 188 h at the current density of 25 mA·cm^(−2).We also construct a large-area NIR QD-OLED(5 cm×5 cm)with desirable uniform *** work opens a new avenue to achieve robust large-area NIR planar light sources for broad applications.

关键词： near-infrared emission PbS quantum dot chloride surface passivation crown ether light-emitting diode

V-shaped substrate for surface and volume enhanced Raman spectroscopic analysis of microplastics

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Frontiers of Environmental Science & Engineering 2022年第11期16卷 213-222页

作者： juan Liu Guanjun xu xuejun Ruan Kejian Li Liwu Zhang Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention Department of Environmental Science&EngineeringFudan UniversityShanghai 200433China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

Research on the microplastics(MPs)is developing towards smaller size,but corresponding methods for the rapid and accurate detection of microplastics,especially nanoplastics still present *** this work,a novel surface and volume enhanced Raman spectroscopy substrate was developed for the rapid detection of microplastic particles below 5μ*** gold nanoparticles(NPs)were deposited onto the surface and into the V-shaped nanopores of anodized aluminum oxide(AAO)through magnetron sputtering or ion sputtering,and then AuNPs@V-shaped AAO SERS substrate was obtained and studied for microplastic *** performance of AuNPs@V-shaped AAO SERS substrate was evaluated through the detection of polystyrene and polymethyl methacrylate *** indicated that individual polystyrene sphere with a diameter of 1μm can be well detected on AuNPs@V-shaped AAO SERS substrate,and the maximum enhancement factor(EF)can reach *** addition,microplastics in ambient atmospheric samples were collected and tested to verify the effectiveness of the AuNPs@V-shaped AAO SERS substrate in the real *** study provides a rapid,economic and simple method for detecting and identifying microplastics with small size.

关键词： SERS V-shaped AAO Microplastic Atmospheric aerosol

Influence of plasma peening on oxidation of H13 hot work steel in water vapor

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中国有色金属学会会刊：英文版 2004年第z1期14卷 305-309页

作者： MIN Yong-an xu Xiao WU Xiao-chun LI Lin xu Luo-ping School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China

The surface oxidation films on H13 steel samples, obtained by different oxidation processes were observed by optical microscope. It is shown that the oxidation speed of H13 steel is increased remarkably due to the surface modification of plasma peening. Further researches were made by XRD, SEM and EDS. The activation of H13 surface caused by plasma peening and the subsequent higher oxygen diffusion rate into the steel seem to be the main reasons of higher oxidation speed. The nitride layer, generally formed on the steel surface under plasma nitriding process, can be substituted by oxide in subsequent oxidation process, which can reduce the risk of heat cracking in some hot work applications. Therefore, the plasma nitriding plus oxidation process is a proper choice for some hot work dies, which demands high hardness to avoid indentation as well as high toughness to avoid cracks.

关键词： oxidation hot work tool steel plasma nitriding surface treatment

Passive, Stable and Order-Adjustable SBS Q-Switching Fiber Laser

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Chinese Physics Letters 2018年第8期35卷 28-31页

作者： Guan Wang Lixin xu chun Gu Department of Optics and Optical Engineering University of Science and Technology of China

We propose a new method to separate different orders of an all-fiber passive Q-switching stimulated Brillouin scattering（SBS） laser. We use two fiber Bragg gratings connected by two circulators for the filtering. We obtain a stabilized pulse laser and measure the pulse width of different orders. The first order of SBS has a central wavelength of 1549.75 nm, an average output power of 9 mW, and a pulse width of 400 ns. The pulse width of SBS is reduced by the higher-order signals with the larger fluctuations.

关键词： SBS Passive Stable and Order-Adjustable SBS Q-Switching Fiber Laser

An Improved Virtual Inertia Algorithm of Virtual Synchronous Generator

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Journal of Modern Power Systems and Clean Energy 2020年第2期8卷 377-386页

作者： Haizhen xu Changzhou Yu chun Liu Qinglong Wang Xing Zhang the Department of Electronic Information and Electrical Engineering Hefei UniversityHefeiChina Anhui Provincial Engineering Laboratory of Renewable Energy and Industrial Energy Conservation Hefei University of TechnologyHefeiChina

Virtual synchronous generator(VSG)simulates the first-order motion equation of a synchronous generator(SG)with the *** can improve the system voltage and frequency support capabilities of a microgrid or a weak *** is now widely applied at a high penetration level of distributed generation(DG)***,because there is a contradiction between active power steady-state deviation of VSG and dynamic impact regulation,the VSG running in grid-connected mode with existing strategies cannot meet the steady and dynamic control ***,an improved virtual inertial control strategy of VSG is proposed in this *** active power impact is reduced effectively under the circumstance of damping coefficient Dωequal to 0 and a large inertia,thus the dynamic characteristic of active power is improved and its steady-state characteristic is ***,based on the analysis of the damping coefficient effect on the system dynamic process,two forms of improved virtual inertia algorithms are put forward by cascading a differential link into different positions of the first-order virtual inertia forward ***,by comparing the characteristics of the system with the two improved algorithms,the improved virtual inertial strategy based on differential compensation is proven to be better,and the design of its parameters is ***,simulation and experimental results verify the effectiveness of the proposed algorithm.

关键词： Virtual synchronous generator(VSG) virtual inertia microgrid distributed generation(DG)

Simulation and verification of core–shell MC carbide design in Fe–C–Ni–V–Ti steel

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Journal of Iron and Steel Research International 2021年第1期28卷 58-65页

作者： Chen‑chong Wang chun‑guang Shen Zhen Zhang Wei xu State Key Laboratory of Rolling and Automation School of Materials Science and EngineeringNortheastern UniversityShenyang 110819LiaoningChina

Thermodynamic theory was used to calculate the formation temperature and site fraction of MC carbides in Fe–C–Ni–V–Ti *** calculation results showed the theoretical formation conditions of core–shell MC ***-step and two-step heat treatment processes were used in Fe–C–Ni–V–Ti alloy to,respectively,obtain homogeneous and core–shell MC carbides,which was consistent with the thermodynamic calculation *** transmission electron microscopy observations showed that the core–shell MC carbide obtained by the two-step heat treatment process contained homogeneous(Ti,V)C as the core and basically VC as the *** mechanical test results proved that compared with homogeneous MC carbides,core–shell MC carbides could improve the basic mechanical properties of the alloy because VC shell greatly increased the bonding strength and separation work of Fe/MC ***,the core–shell MC carbide with a VC shell structure can be a better grain refiner and can be used in steels with a high standard of fracture toughness.

关键词： Core–shell carbide Thermodynamic calculation Microstructure observation Grain refiner Mechanical

A Multi-dimensional Index Structure Based on Improved VA-file and CAN in the Cloud

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International Journal of Automation and computing 2014年第1期11卷 109-117页

作者： chun-Ling Cheng chun-Ju Sun Xiao-Long xu Deng-Yin Zhang College of Computer Nanjing University of Posts and Telecommunications Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and TelecommunicationsMinistry of Education Jiangsu Province

Currently,the cloud computing systems use simple key-value data processing,which cannot support similarity search efectively due to lack of efcient index structures,and with the increase of dimensionality,the existing tree-like index structures could lead to the problem of"the curse of dimensionality".In this paper,a novel VF-CAN indexing scheme is ***-CAN integrates content addressable network(CAN)based routing protocol and the improved vector approximation fle(VA-fle) *** are two index levels in this scheme:global index and local *** local index VAK-fle is built for the data in each storage ***-fle is thek-means clustering result of VA-fle approximation vectors according to their degree of *** cluster forms a separate local index fle and each fle stores the approximate vectors that are contained in the *** vector of each cluster center is stored in the cluster center information fle of corresponding storage *** the global index,storage nodes are organized into an overlay network CAN,and in order to reduce the cost of calculation,only clustering information of local index is issued to the entire overlay network through the CAN *** experimental results show that VF-CAN reduces the index storage space and improves query performance efectively.

关键词： Cloud computing index similarity search clustering vector approximation fle(VA-fle) content addressable network(CAN)

Highly dispersed Ni/MgO-mSiO_(2)catalysts with excellent activity and stability for dry reforming of methane

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Nano Research 2022年第6期15卷 5004-5013页

作者： Fang Zeng juan Zhang Run xu Rongjun Zhang Jianping Ge Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200062China Department of Coal and Syngas Conversion Research Institute of Petroleum ProcessingSINOPECBeijing 100083China

Highly dispersed Ni catalyst and alkaline promoters supported by mesoporous SiO_(2)nanospheres were synthesized and applied as an active and stable catalyst for dry reforming of methane(DRM).The as-prepared Ni/MgO-mSiO_(2)catalyst showed stable conversions of CH4 and CO_(2)around 82%and 85%in 120 h of DRM reaction,which was superior in performance compared to similar catalysts in *** on the transmission electron microscope(TEM)images,energy-dispersive spectroscopy(EDS),CO-pulse adsorption,temperature programmed reduction of the oxidized catalysts by hydrogen(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS),temperature-programmed desorption of CO_(2)(CO_(2)-TPD),and thermal gravitational analysis(TGA),the promotion effect of MgO on the Ni catalyst was systematically *** introduction of Mg^(2+)in synthesis enhanced the interaction between Ni^(2+)and mSiO_(2),which led to a high dispersion of active centers and a strong“metal–support”interactions to inhibit the sintering and deactivation of Ni at reaction *** the other hand,Ni and MgO nanoparticles formed adjacently on mSiO_(2),where the“Ni-MgO”interface not only improved the Ni0 distribution and promoted the cracking of CH_(4)but also promoted the activation of CO_(2)and the elimination of carbon deposits.A high and stable conversion of CH4 and CO_(2)were then achieved through the synergistic effect of Ni catalyst,MgO promoter,and mSiO_(2)support.

关键词： Ni-based catalyst dry reforming of methane mesoporous SiO_(2) MgO alkaline

NONLINEAR DYNAMICS MODFLING OF MECHANICAL PERIODICITY OF END DIASTOLIC VOLUME OF LEFT VENTRICLE

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Applied Mathematics and Mechanics(English Edition) 2001年第10期22卷 1183-1191页

作者： xu Shi-xiong(许世雄) MAO Xiao-chun(毛晓春) Mechanics and Engineering Science Department Fudan UniversityShanghai 200433 P R China Mechanics and Engineering Science Department Fudan UniversityShanghai 200433 P R China

The cardiovascular system with a lumped parameter model is treated, in which the Starling model is used to simulate left ventricle and the four-element Burattini & Gnudi model is used in the description of arterial system. Moreover, the feedback action of arterial pressure on cardiac cycle is taken into account. The phenomenon of mechanical periodicity (MP) of end diastolic volume (EDV) of left ventricle is successfully simulated by solving a series of one-dimensional discrete nonlinear dynamical equations. The effects of cardiovascular parameters on MP is also discussed.

关键词： left ventricle end diastolic volume mechanical periodicity nonlinear dynamics