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Molecular Plant 2019年第11期12卷 1515-1523页

作者： Zai zheng zhen Wang Xiaoyue Wang Dong Liu MOE Key Laboratory of Bioinformatics Center for Plant BiologySchool of Life SciencesTsinghua UniversityBeijing 100084China

To tolerate phosphate(Pi)deficiency in the environment,plants alter their developmental and metabolic *** the past two decades,researchers have extensively used Petri dish-grown seedlings of the model plant Arabidopsis thaliana to study the molecular mechanisms underlying root developmental responses to Pi deficiency.A typical developmental response of the Petri dish-grown Arabidopsis seedlings to Pi deficiency is the inhibited growth of primary root(PR).This response is generally thought to enhance the production of lateral roots and root hairs,which increases the plant’s ability to obtain Pi and is therefore regarded as an active cellular ***,we report that direct illumination of root surface with blue light is critical and sufficient for Pi deficiency-induced inhibition of PR growth in Arabidopsis *** further show that a blue light-triggered malate-mediated photo-Fenton reaction and a canonical Fenton reaction form an Fe redox cycle in the root *** Fe redox cycle results in the production of hydroxyl radicals that inhibit PR *** addition to revealing the molecular mechanism underlying Pi deficiency-induced inhibition of PR growth,our work demonstrated that this developmental change is not an active cellular response;instead,it is a phenotype resulting from root growth in transparent Petri *** finding is significant because illuminated,transparent Petri dishes have been routinely used to study Arabidopsis root responses to environmental changes.

关键词： phosphate deficiency root response blue light Fe redox cycle hydroxyl radicals

Field-Aligned Currents at the PSBL on 17 August 2001 Storm: Relationships with solar Wind Conditions

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Chinese Physics Letters 2011年第9期28卷 267-270页

作者： CHENG zheng-Wei SHI Jian-Kui ZHANG Tie-Long WANG sheng-Guo LIU zhen-Xing State Key Laboratory of Space Weather CSSAR/CASBeijing 100190 Space Research Institute Austrian Academy of SciencesGrazAustria Beijing Institute of Applied Meteorology Beijing 100083

Using magnetic field and plasma data acquired with Cluster spacecrafts,we investigate the relationship between the field-aligned currents(FACs)at the plasma sheet boundary layer(PSBL)and solar wind dynamic pressure,as well as the interplanetary magnetic field(IMF)By on 17 August 2001 *** studies reveal that FAC density at the PSBL in the magnetotail in the storm time is controlled mainly by the solar wind dynamic pressure rather than IMF *** FACs at the PSBL are associated with the low−altitude region-1 current and have the same polarity as region-1 current in the dawn *** the polar region,the footprints of the FACs at the PSBL expand *** data analysis also shows that a very strong FAC with a density over 40 nA·m^(−2) appeared in this storm time when a substorm just occurred.

关键词： storm altitude Wind

Stability of proteins with multi-state unfolding behavior

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Science China Chemistry 2012年第7期55卷 1351-1357页

作者： YANG Binsheng SONG zhen zheng XiaoYan ZHAO YaQin Institute of Molecular Science Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of EducationShanxi UniversityTaiyuan 030006China

A new model used to calculate the free energy change of protein unfolding is presented. In this model, proteins are considered to be composed of structural elements. The unfolding of a structural element obeys a two-state mechanism and the free energy change of the element can be obtained by a linear extrapolation method. If a protein consists of the same structural elements, its unfolding will displays a two-state process, and only the average structural element free energy change 〈△G0 element（H2O）〉 can be measured. If protein consists of completely different structural elements, its unfolding will show a multi-state behavior. When a protein consists of n structural elements its unfolding will shows a （n＋1）-state behavior. A least-squares fitting can be used to analyze the contribution of each structural element to the protein and the free energy change of each structural element can be obtained by using linear extrapolation to zero denaturant concentration, not to the start of each transition. The measured △Gn protein（H2O） is the sum of the free energy change for each structural element. Using this new model, we can not only analyze the stability of various proteins with similar structure and similar molecular weight, which undergo multi-state unfolding processes, but also compare the stability of proteins with different structures and molecular weights using the average structural element free energy change 〈△G0 element（H2O）〉. Although this method cannot completely provide the exact free energy of proteins, it is better than current methods.

关键词： new model protein stability multi-state unfolding CopC

Fast radio burst search： cross spectrum vs. auto spectrum method

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Research in Astronomy and Astrophysics 2018年第6期18卷 87-92页

作者： Lei Liu Weimin zheng zhen Yan Juan Zhang Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing 210008 China Shanghai Key Laboratory of Space Navigation and Positioning Techniques Shanghai 200030 China

The search for fast radio bursts(FRBs) is a hot topic in current radio astronomy studies. In this work, we carry out a single pulse search with a very long baseline interferometry(VLBI) pulsar observation data set using both auto spectrum and cross spectrum search methods. The cross spectrum method,first proposed in Liu et al., maximizes the signal power by fully utilizing the fringe phase information of the baseline cross spectrum. The auto spectrum search method is based on the popular pulsar software package PRESTO, which extracts single pulses from the auto spectrum of each station. According to our comparison, the cross spectrum method is able to enhance the signal power and therefore extract single pulses from data contaminated by high levels of radio frequency interference(RFI), which makes it possible to carry out a search for FRBs in regular VLBI observations when RFI is present.

关键词： techniques: interferometric radio continuum: general methods: data analysis pulsars: general

Enhanced quality of Al_(2)O_(3)/SiC gate stack via microwave plasma annealing

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Rare Metals 2024年第10期43卷 5362-5371页

作者： Nan-Nan You Xin-Yu Liu Qian Zhang zhen Wang Jia-Yi Wang Yang Xu Xiu-Yan Li Yu-zheng Guo sheng-Kai Wang High-Frequency High-Voltage Device and Integrated Circuits R&D Center Institute of Microelectronics of the Chinese Academy of SciencesBeijing 100029China School of Integrated Circuits University of Chinese Academy of SciencesBeijing 100049China School of Electrical Engineering and Automation Wuhan UniversityWuhan430072China Department of Micro/Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The high-quality gate dielectric on silicon carbide(SiC)surface is critical to fabricate high-performance SiC metal-oxide-semiconductor field-effect transistors(MOSFETs).This research employs microwave plasma annealing(MPA)to obtain high-quality Al_(2)O_(3)/SiC gate *** designing MPA atmosphere and optimizing the plasma power,the SiC MOS capacitor with a Al_(2)O_(3)dielectric film shows the enhanced *** interface state density is reduced by 1 order of magnitude to 6×10^(11)cm^(-2)·eV^(-1),the breakdown electric field is increased,and the voltage shift is effectively suppressed Besides,the mechanism of MPA process is discussed in terms of the thermal effect and reactant species.X-ray photoelectron spectroscopy(XPS)results unveil oxygen plasma plays the main *** plasma power during the MPA process results in defect repairs of the firstneighbor Al-O bonding and partial removal of Al-O-H bond from the interface *** study demonstrates that MPA process is an effective option to realize highquality dielectric and interface on SiC.

关键词： Silicon carbide Al_(2)O_(3) Metal-oxide-semiconductor Microwave plasma annealing Defect repairs X-ray photoelectron spectroscopy

Numerical Studies of Estimation of Fracture Parameters for Mismatched Welded Joints with HAZ Cracks

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Journal of Iron and Steel Research International 2015年第9期22卷 846-851页

作者： Kun LING zheng-dong WANG Fu-zhen XUAN Key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and Technology

An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone（HAZ）.The fracture parameters Jand C＊are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS.A middle crack tension（M（T））specimen is utilized in the analysis for different material properties and geometries of the *** influence of mechanical property and geometry on the fracture parameters Jand C＊of the specimen is discussed for the welded joints with HAZ *** results suggest that the HAZ property is a significant factor in the estimation of Jand C＊for the mismatched welded joint with HAZ crack.

关键词： mismatched welded joint tri-material assumption heat affected zone(HAZ) J-integral C*parameter

Study on the subgrade deformation under high-speed train loading and water–soil interaction

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Acta Mechanica Sinica 2016年第2期32卷 233-243页

作者： Jian Han Guo-Tang Zhao Xiao-zhen sheng Xue-Song Jin State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China China Railway Corporation Beijing 100844 China

It is important to study the subgrade characteristics of high-speed railways in consideration of the water–soil coupling dynamic problem,especially when high-speed trains operate in rainy *** study develops a nonlinear water–soil interaction dynamic model of slab track coupling with subgrade under high-speed train loading based on vehicle–track coupling *** using this model,the basic dynamic characteristics,including water–soil interaction and without water induced by the high-speed train loading,are *** main factors-the permeability coefficien and the porosity-influencin the subgrade deformation are *** developed model can characterize the soil dynamic behaviour more realistically,especially when considering the influenc of water-rich soil.

关键词： Water–soil interaction High-speed train loading Finite difference method Subgrade deformation Permeability coefficien Porosity

Biomechanical and dynamic mechanism of locust take-off

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Acta Mechanica Sinica 2014年第5期30卷 762-774页

作者： Dian-sheng Chen Jun-Mao Yin Ke-Wei Chen zhen Li Robotics Institute Beihang University

The biomimetic locust robot hopping vehicle has promising applications in planet exploration and reconnaissance. This paper explores the bionic dynamics model of locust jumping by using high-speed video and force analysis. This paper applies hybrid rigid-flexible mechanisms to bionic locust hopping and studies its dynamics with emphasis laid on the relationship between force and jumping performance. The hybrid rigid-flexible model is introduced in the analysis of locust mechanism to address the principles of dynamics that govern locust joints and mechanisms during energy storage and take-off. The dynamic response of the biomimetic mechanism is studied by considering the flexi- bility according to the locust jumping dynamics mechanism. A multi-rigid-body dynamics model of locust jumping is established and analyzed based on Lagrange method; elastic knee and tarsus mechanisms that were proposed in previous works are analyzed alongside the original bionic joint configurations and their machinery principles. This work offers primary theories for take-off dynamics and establishes a theoretical basis for future studies and engineering applications.

关键词： Locust take-off- Dynamics Hybrid rigid- flexible Hopping mechanism

Influence of Re-Ti modification on the high impact wear resistance of high Si bainitic cast steel

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 756-762页

作者： Jin-feng Huang Hong-sheng Fang Yan-kang zheng State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijnig 100083 China Department of Materials Science and Engineering Tsinghna University Beijing 100084 China

The effect of rare earth （Re） and titanium （Ti） multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically. The experiments show that the impact wear resistance can be improved greatly with the addition of Re and Ti. Its wear loss is only about 1/3-1/2 as large as that of the unmodified bainitic cast steel. By the Re/Ti modification, coarse dendrite grains and bainitic/martensite duplex structure have been refined effectively, and the impact toughness of the bainitic cast steel is nearly tripled （10 mm×10 mm×55 mm, with unnotched sample）. Consequently, the modified bainitic cast steel possesses good wear resistance under high im- pact. For both modified and unmodified bainitic cast steels, high hardness white layer and deformed zone are developed beneath the worn surface under the high impact wear, but the formation and propagation of cracks are different for these bainitic casting steels. Different mod- els for the formation and propagation of cracks for both modified and unmodified bainitic cast steels under high impact wear are proposed.

关键词： cast steel modification grain refmement impact wear spalling

Feasibility and safety of sorafenib treatment in hepatocellular carcinoma patients with spontaneous rupture

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World Journal of Gastroenterology 2014年第43期20卷 16275-16281页

作者： Shun-zhen zheng De-Jie Liu Ping Sun Guang-sheng Yu Yan-Tian Xu Wei Gong Jun Liu Department of Liver Transplantation and Hepatobiliary Surgery Shandong Provincial Hospital Affiliated to Shandong University Department of Anesthesiology Qilu HospitalShandong University Department of Biochemistry and Molecular Biology Shandong University School of Medicine

AIM: To report the outcome of patients with ruptured hepatocellular carcinoma (HCC) treated at a single center during a 5-year period.

关键词： Sorafenib Hepatocellular carcinoma Spontaneous rupture Efficacy Safety