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Microstructural evolution of titanium matrix composite coatings reinforced by in situ synthesized TiB and TiC by laser cladding

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 481-488页

作者： Jun li zhi-shui Yu hui-ping Wang Man-ping li School of Materials Engineering Shanghai University of Engineering Science Shanghai 201620 China

Titanium-based composite coatings reinforced by in situ synthesized TiB and TiC particles were successfully fabricated on Ti6Al4V by laser cladding using Ti-B_4C-Al or Ti-B_4C-C-Al powders as the precursor *** microstructural and metallographic analyses were made by X-ray diffraction（XRD）,optical microscope（OM）,scanning electron microscopy（SEM）,and electron probe microanalysis （EPMA）.The results show that the coatings are mainly composed ofα-Ti cellular dendrites and a eutectic transformation product in which a large number of coarse and fine needle-shaped TiB and a few equiaxial TiC particles are homogeneously embedded.A thin dilution zone with a thickness of about 100μm is present at the interface,and it consists of a few TiB and TiC reinforcements and a large number of lamella grains growing parallel to the heat flux direction in which a thin needle-shaped microstructure exists due to the martensitic transformation. The microstructural evolution can be divided into four stages：precipitation and growth of primaryβ-Ti phase,formation of the binary eutecticumβ-Ti＋TiB,formation of the ternary eutecticumβ-Ti＋TiB＋TiC,and solid transformation fromβ-Ti toα-Ti.

关键词： coating laser cladding in-situ synthesis microstructure

Convergence proof of the DSMC method and the Gas-Kinetic Unified Algorithm for the Boltzmann equation

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Science China(Physics,Mechanics & Astronomy) 2013年第2期56卷 404-417页

作者： li zhi hui FANG Ming JIANG XinYu WU Junlin Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center National Laboratory for Computational Fluid Dynamics

This paper investigates the convergence proof of the Direct Simulation Monte Carlo(DSMC) method and the Gas-Kinetic Unified Algorithm in simulating the Boltzmann *** can be shown that the particle velocity distribution function obtained by the DSMC method converges to a modified form of the Boltzmann equation,which is the equation of the gas-kinetic unified algorithm to directly solve the molecular velocity distribution *** convergence is derived through mathematical *** collision frequency is presented using various molecular models and the local equilibrium distribution function is obtained by Enskog expansion using the converged equation of the DSMC *** two expressions agree with those used in the unified *** validation of the converging consistency between these two approaches is illustrated by simulating the pressure driven Poiseuille flow in the slip transition flow regime and the two-dimensional and three-dimensional flows around a circular cylinder and spherical-cone reentry body covering the whole flow regimes from low speed micro-channel flow to high speed non-equilibrium aerothermodynamics.

关键词： Boltzmann equation DSMC method Gas-Kinetic Unified Algorithm velocity distribution function convergence aerothermodynamics covering flow regimes

Regulation of Water Deficit-Induced Abscisic Acid Accumulation by Apoplastic Ascorbic Acid in Maize Seedlings

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Journal of Integrative Plant Biology 2005年第11期47卷 1335-1344页

作者： Jian-Fang HU Gui-Fen li zhi-hui GAO lin CHEN hui-Bo REN Wen-Suo JIA College of Agronomy and Biotechnology State Key Laboratory of Plant Physiology and Biochemistry China Agricultural University Beijing 100094 China

Water deficit-induced abscisic acid （ABA） accumulation is one of the most important stress signaling pathways in plant cells. Redox regulation of cellular signaling has currently attracted particular attention, but much less is known about its roles and mechanisms in plant signaling. Herein, we report that water deficit-induced ABA accumulation could be regulated by ascorbic acid （AA）-controlled redox status in leave apoplast. The AA content in non-stressed leaves was approximately 3 umol/g FW, corresponding to a mean concentration of 3 mmol/L in a whole cell. Because AA is mainly localized in the cytosol and chloroplasts, the volume of which is much smaller than that of the whole cell, AA content in cytosolic and chloroplast compartments should be much higher than 3 mmol/L. Water deficit-induced ABA accumulation in both leaf and root tissues of maize seedlings was significantly inhibited by AA and reduced glutathione （GSH） at concentrations of 500 umol/L and was completely blocked by 50 mmol/L AA and GSH. These results suggest that the AA-induced inhibition of ABA accumulation should not occur at sites where AA exists in high concentrations. Although water deficit led to a small increase in the dehydroascorbic acid （DHA） content, no significant changes in AA content were observed in either leaf or root tissues. When compared with the whole leaf cell, the AA content in the apoplastic compartment was much lower （i.e. approximately 70 nmol/g FW, corresponding to 0.7 mmol/L）. Water deficit induced a significant decrease （approximately 2.5-fold） in the AA content and an increase （approximately 3.4-fold） in the DHA content in the apoplastic compartment, thus leading to a considerably decreased redox status there, which may have contributed to the relief of AA-induced inhibition of ABA accumulation, alternatively, promoting water deficit-induced ABA accumulation. Reactive oxygen species （ROS） could not mimic water deficit in inducing ABA accumulation, suggesting that the

关键词： abscisic acid (ABA) ascorbic acid (AA) maize (Zea mays) reactive oxygen species waterdeficit.

Spatial Distribution of Soil Organic Matter and Nutrients in the Pear Orchard Under Clean and Sod Cultivation Models

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Journal of Integrative Agriculture 2013年第2期12卷 344-351页

作者： XU ling-fei ZHOU Peng HAN Qing-fang li zhi-hui YANG Bao-ping NIE Jun-feng College of Horticulture Northwest A&F University Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China Ministry of Agriculture Key Laboratory of Crop Production and Ecology Minister of Agriculture

The soil organic matter and nutrients are fundamental for the sustainability of pear production, but little is known about the spatial distribution of soil organic matter and nutrients in a pear orchard. With the soil of the pear （cv. Dangshansu on *** Bunge. rootstock） orchard under clean and sod cultivation models as test materials, the experiment was conducted to evaluate spatial variability of soil organic matter （SOM）, total nitrogen （STN）, total phosphorus （STP）, total potassium （STK）, available nitrogen （SAN）, and available potassium （SAK） in and between rows at different soil depths （0-60 cm）. The SOM, STN, STP, STK, SAN and SAK of the different soil layers under the two tillage models were different in the vertical direction. The SOM, STN, STP and SAN in the 0-20 cm soil layer were higher than those in the 20-40 and 40- 60 cm soil layers. The STK of 40-60 cm soil layer was higher than that in the 0-20 and 20-40 cm soil layers. The STK increased with the depth of soil in the vertical direction in the clean cultivated pear orchard. Variability of the SOM, STN, STP, STK, SAN and SAK of sample sites in between rows of the same soil layer was found in the pear orchard soil in the horizontal direction under clean and sod cultivation management systems, except that STK of all sites did not show the difference in identical soil layers in the pear orchard under clean cultivation. The sod cultivation model improved the SOM, STN, and STK in the 0-20 cm soil layer in the pear orchard, and the three components increased by 12.8, 12.7 and 7.3% compared to clean cultivation, respectively. The results can be applicable to plan collection of orchard soil samples, assess orchard soil quality, and improve orchard soil management practices.

关键词： spatial distribution soil organic matter soil nutrients clean cultivation sod cover pear orchard

Effect of li addition on mechanical properties and ageing precipitation behavior of extruded Al-3.0 Mg-0.5 Si alloy

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Journal of Central South University 2021年第9期28卷 2636-2646页

作者： YANG Xiao-kun XIONG Bai-qing li Xi-wu YAN li-zhen li zhi-hui ZHANG Yong-an li Ya-nan WEN Kai liU Hong-wei State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The effect of li(2.0 wt%)addition on mechanical properties and ageing precipitation behavior of Al-3.0 Mg 0.5 Si was investigated by tensile test,dynamic elasticity modulus test,scanning electron microscopy(SEM),transmission electron microscopy(TEM)and high-resolution transmission electron microscopy(HRTEM)*** results show that the tensile strength of the li-containing alloy can be significantly improved;however,the ductility is sharply decreased and the fracture mechanism changes from ductile fracture to intergranular *** elasticity modulus of the li-containing alloy increases by 11.6%compared with the base *** microstructure observation shows that the li addition can absolutely change the precipitation behavior of the base alloy,andδ′-Al_(3)li phase becomes the main ***,β′′-Mg_(2)Si andδ′-Al_(3)li dual phases precipitation can be visibly observed at 170℃ ageing for 100 h,although the quantity ofδ′-Al_(3)li phase is more thanβ′′-Mg_(2)Si *** width of the precipitate-free zone(PFZ)of the li-containing alloy is much wider at the over-ageing state than the base alloy,which has a negative impact on the ductile and results in the decrease of elongation.

关键词： Al-3.0 Mg-0.5 Si alloy li addition microstructure ageing behavior mechanical properties dynamic elasticity modulus

Inactivation gating determines drug potency:a common mechanism for drug blockade of HERG channels

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Acta Pharmacologica Sinica 2004年第5期25卷 12-18页

作者： Bao-feng YANG1, Dong-hui XU2, Chao-qian XU, Zhe li, zhi-min DU, hui-zhen WANG, De-li DONGDepartment of Pharmacology, Harbin Medical University, Harbin 150086, China 2Department of Pharmacy, Sun Yat-sen University, Guangzhou 510080, China Department of Pharmacology Harbin Medical University Department of Pharmacy Sun Yat-sen University

AIM: To determine the mechanisms of interactions between different drugs and HERG channels. METHODS:Various antiarrhythmic (dofetilide, quinidine, azimilide, RP58866) and non-antiarrhythmic (terfenadine, nicotine)agents were used on HERG channels expressed in Xenopus oocyte. Whole-cell voltage-clamp techniques wereused. RESULTS: All drugs produced concentration-dependent block of HERG current. The inhibition was mark-edly facilitated with voltage protocols favoring channel inactivation (eg, less negative holding potentials). Maneu-vers that weakened channel inactivation (eg, elevation of external K+), relieved HERG blockade by all drugs. Moreover,the inhibitory potency was reduced by at least 20-300 fold with varying compounds when rapid C-type inactivationwas removed by a mutation located between the transmembrane domains 5 and 6 (S631A). CONCLUSION: Theinactivation gating of HERG channels determines the blocking potency of drugs. This mechanism might be com-mon to drugs of various classes.

关键词： antiarrhythmic agents potassium channels mutation channel inactivation patch-clamp techniques oocytes Xenopus

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加速器电容耦合的研究

高能物理与核物理 2006年第7期30卷 680-683页

作者：李智慧中国科学院近代物理研究所兰州730000

首先从腔体的等效集总参数电路出发,推导出了腔体等效输入阻抗和腔体特性参数,如谐振频率、并联阻抗及耦合电容的关系．以此为出发点,得到了理想耦合所需要的耦合电容大小和腔体参数的关系,总结出了高频腔体电容耦合系统设计的一般方法... 详细信息

首先从腔体的等效集总参数电路出发,推导出了腔体等效输入阻抗和腔体特性参数,如谐振频率、并联阻抗及耦合电容的关系．以此为出发点,得到了理想耦合所需要的耦合电容大小和腔体参数的关系,总结出了高频腔体电容耦合系统设计的一般方法．以一台质子回旋加速器模型腔体为例,对计算结果和测量结果进行对比分析,讨论了其结果的可靠性及使用范围．

关键词：电容耦合匹配反射系数

How R&D investment promotes green technology innovation in the context of digitalization?-An empirical analysis based on provincial panel data

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Ecological Economy 2024年第1期20卷 39-52页

作者： liU Jie li zhi-hui WEI Fang-xin School of Business Beijing Union UniversityBeijing 100025CHINA China Railway 22^(nd) Bureau Group Second Engineering Co. LtdBeijing 100041CHINA Center for Nuclear and Radiation Safety Ministry of Ecology and EnvironmentBeijing 100082CHINA

Green technology innovation is an important driving force and source to promote my country’s high-quality development,and it is the core path to achieve sustainable *** paper uses my country’s provincial panel data from 2016 to 2019 to study the impact mechanism of R&D investment on green technology innovation,and introduces the level of digitization,using the panel threshold model to discuss its role in the impact mechanism of R&D investment on green technology *** study found that when the level of digitalization in a region is low,increasing R&D investment does not necessarily improve the ability of green technology innovation;when the level of digitalization is relatively high,R&D investment has a positive role in promoting green technology ***,it is necessary to improve policies to encourage enterprises to increase investment in research and development;at the same time,it is necessary to promote the coordinated development of digital foundation,digital investment,digital literacy,digital economy and digital application,and promote the deep integration of digitalization and green technology innovation.

关键词： green technology innovation R&D investment digital level panel model

Iris Identification Technology Based on Multiwavelets

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Journal of Bionic Engineering 2005年第4期2卷 203-207页

作者： Wei lian-xin Ma Fu-ming Xu Tao li zhi-hui Wu Deng-feng Institute of Mathematic. Qianwei Campns Jilin University Changchan 130012 P. R. China College of Mechanical Science and Engineering Nanling Campus Jilin University Changchun 130022 P. R. China College of Computer Science and Technology Qianwei Campus Jilin University Changchun 130012 P. R. China

A new method for iris identification based on multiwavelets is proposed. By means of the properties of multiwavelets, such as orthogonality, symmetry, vanishing moments and approximation order, the iris texture can be simply presented. A brief overview of muhiwavelets is presented at first. Iris identification system and iris texture feature presentation and recognition based on multiwavelets a,e introduced subsequently. And the experiment indicates the validity of this method finally.

关键词： multiwavelets iris identification texture feature