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The first 2D organic-inorganic hybrid relaxor-ferroelectric single crystal

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Science China Chemistry 2023年第2期66卷 466-474页

作者： Wenjuan Wei hongqiang gao Ming Fang Yang Yang Yan Guan Yen Wei Yunzhi Tang Department of Chemistry Tsinghua UniversityBeijing100084China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou341000China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing100084China The Analytical Instrumentation Center of Peking University the Center for Physicochemical Analysis and Measurements in ICCASBeijing100871China

Inorganic relaxor ferroelectric solid solution single crystals are spurring new generations of high performance electromechanical devices,including transducers,sensors,and actuators,due to their ultrahigh electric field induced strain,large piezoelectric constant,high electromechanical coupling factor and low dielectric ***,relaxor ferroelectric single crystals found in organic-inorganic hybrid perovskites are very limited,but achieving these superior properties in them will be of great significance in the design of modern functional ***,here the first two-dimensional(2D)organic-inorganic hybrid relaxor ferroelectric single crystal,[Br(CH_(2))_(3)NH_(3)]_(2)PbBr_(4)(BPA_(2)-PbBr_(4),BPA=3-bromopropylamine),achieves some of superior ***,BPA_(2)-PbBr_(4)reveals a successive relaxor ferroelectric-ferroelectric-paraelectric phase transitions accompanying by a large degree of relaxationΔT_(relax)=61 K and ultralow energy loss(tanδ<0.001).Meanwhile,it exhibits a superior second harmonic generation(SHG)effect with maximum value accounts for 95%of the standard KDP due to great deformation of structure(3.2302×10^(-4)).In addition,temperature dependent luminescence spectra(80-415 K)exhibit fluorescence and phosphorescence overlapping emission originated from inorganic and organic components with the nanosecond-scale short lifetime and the millisecond-scale long lifetime,respectively,and the color of the emitted light is continuously adjustable,which is the first to achieve luminescence and relaxor ferroelectricity compatibility.

关键词： 2D organic-inorganic hybrid perovskites ferroelectrics relaxor ferroelectrics paraelectrics luminescence

Rational design of imine-linked three-dimensional mesoporous covalent organic frameworks with bor topology

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SusMat 2022年第2期2卷 197-205页

作者： Zonglong Li Chouhung Hsueh Zhuozhuo Tang Jia Chen Xiaolin Wang Hao Cui Yang Yang Xiaodan Wang Dongsheng Ren hongqiang gao Mingyang Li Hong Xu Xiangming He Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijingChina

Three-dimensional(3D)covalent organic frameworks(COFs)possess great potential applications in various *** 3D COFs with large pore sizes is extremely challenging due to the interpenetration and ***,we report a series of crystalline imine-linked 3D COFs(3D-bor-COF-1,3D-borCOF-2,3D-bor-COF-3)with mesoporous channels through rationally designing the topology *** 3D-bor-COFs display permanent porosity and Brunauer–Emmett–Teller(BET)surfaces of 3205.5,1752.7,and 2077.3 m2 g−1(SLangmuir=4277.7,2480.3,and 2698.0 m2 g−1),*** pore sizes of 3Dbor-COFs were confirmed by the lattice fringes from high-resolution transmission electron microscopy,as well as structural simulation and nitrogen adsorption isotherm analysis.3D-bor-COFs display large pore sizes(3.8 nm for 3D-borCOF-3),which is among the highest record of 3D *** to the unstackedaromatic pore environment and high specific surface area,3D-bor-COFs display excellent adsorption capacity for benzene vapor(1203.9 mg g−1 for 3D-bor-COF-3)under 298 K,which is three times higher than that of the best-reported 2D *** work not only provides inspiration for designing 3D mesoporous imineCOFs,but also demonstrates a strategy for constructing aromatics adsorption materials.

关键词： benzene vapor uptake covalent organic framework large pore size lattice fringes topology configuration

“第一感觉”可靠吗?——高考语文选择题答题情况调查研究

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上海教育科研 2011年第6期 51-52页

作者：高洪强闫凤芹华东师范大学心理与认知科学学院 200062 福建省厦门海沧实验中学 361026

本文对考生完成高考语文选择题时的修改答案行为进行了实证研究,通过抽取3550份试卷的两道选择题的答题情况,统计了考生在真实考试中修改答案的比例、修改次数、修改前的正确率和修改后的争取率。研究发现,考生修改行为很少,一次修改是... 详细信息

本文对考生完成高考语文选择题时的修改答案行为进行了实证研究,通过抽取3550份试卷的两道选择题的答题情况,统计了考生在真实考试中修改答案的比例、修改次数、修改前的正确率和修改后的争取率。研究发现,考生修改行为很少,一次修改是有利的,而多次修改并不有利。

关键词：高考语文选择题第一感觉实证研究

Record-high efficiency perovskite LEDs achieved by accelerating radiative recombination

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Science China Materials 2024年第9期67卷 3039-3040页

作者： Feng gao Department of Physics Chemistry and BiologyLinköping UniversityLinköping58183Sweden

Light-emitting diodes(LEDs)have revolutionized the lighting and displays due to their superior energy *** increasing demand for more efficient and brighter thin-film LEDs in flat-panel displays and solid-state lighting applications has driven extensive research into perovskite materials,which show great promise for high brightness and efficiency.

关键词： lighting radiative high

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Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1637-1648页

作者： Guiyun gao Chenghu Wang Ke gao National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing100085China Beijing Engineering Research Center of Earthquake Observation Beijing100085China Key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing100085China Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen518055China

The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor ***,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable *** this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests *** shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo ***,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress *** inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress *** stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)*** results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress *** inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints *** M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole.

关键词： Stress tensor Hydraulic tests on pre-existing fractures Mean stress Stress constraint Hydraulic fracturing

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即刻种植中采用上颌磨牙后区取骨的临床观察

中国口腔种植学杂志 2020年第2期25卷 80-81,89页

作者：高洪强沈阳市第一人民医院口腔科 116000

目的:探讨上颌磨牙后区取出骨在即刻种植中的应用效果观察。方法:选择2017年5月到2018年5月来就诊的40名患者,均为即刻种植患者,共48枚种植体,其中采用上颌磨牙后区取骨26枚,设为实验组;植入人工骨粉的22枚,设为对照组。比较两组负重1... 详细信息

目的:探讨上颌磨牙后区取出骨在即刻种植中的应用效果观察。方法:选择2017年5月到2018年5月来就诊的40名患者,均为即刻种植患者,共48枚种植体,其中采用上颌磨牙后区取骨26枚,设为实验组;植入人工骨粉的22枚,设为对照组。比较两组负重1年的存留率;探诊深度(PD)、种植体周改良出血指数(m BI)、种植体周菌斑指数(PLI)。数据用PASW statistic 16.0软件进行统计学分析。结果:两组负重1年存留率为100%;两组骨吸收量、牙龈稳定性没有显著性差异。结论:即刻种植中使用上颌磨牙后区取骨可以取得满意的临床效果。

关键词：上颌磨牙后区即刻种植人工骨粉

Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： Kun gao Yan Peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting *** effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in *** each rotation,the casting wheel passes through four different spray *** results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,*** temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

Numerical simulation of fluid flow and free surface fluctuations during wheel and belt casting process

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Journal of Iron and Steel Research International 2024年第5期31卷 1117-1126页

作者： Kun gao Yan Peng National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast *** lower level height tends to entrap inclusions in the molten *** the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was *** transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid *** results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the *** is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in *** jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged *** with the industrial observation and simulation results,the shape of the free surface is a wave that varies with *** addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.

关键词： Fluid flow Free surface Wheel and belt caster Large eddy simulation Volume of fluid method

On the core entropy of Newton maps

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Science China Mathematics 2024年第1期67卷 77-128页

作者： Yan gao Department of Mathematics Shenzhen UniversityShenzhen 518060China

In this paper,we define the core entropy for postcritically-finite Newton maps and study its continuity within this *** show that the entropy function is not continuous in this family,which is different from the polyn... 详细信息

关键词： core entropy extended Newton graph critical marking polynomial Newton map