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Chinese Physics Letters 2006年第5期23卷 1253-1256页

作者：侯廷平王仁卉桂嘉年王建波赵山东郭俊清 Department of Physics Wuhan University Wuhan 430072 Centre for electron microscopy Wuhan University Wuhan 430072 Furukawa Co. Ltd Tsukuba Ibaraki 305-0856 Japan

Similarity in the electron diffraction patterns of the Cd5.7 Yb icosahedral quasicrystal and its cubic approximant Cd6 Yb crystal is studied in detail by using transmission electron microscopy. The icosahedral twofold axes are parallel to the cubic （1ττ^2）（τ= 1.618…） or （0 0 1） directions, the icosahedral pseudo-twofold axes are parallel to the cubic （15 21 25） directions, the icosahedral threefold axes are parallel to the cubic 〈1 1 1〉 and the icosahedral fivefold are parallel to the cubic 〈0 1 τ〉 directions. Based on those observations a general stereographic projection is given to illustrate the exact orientation relationship.

关键词： CD-CA ALLOYS YB

Probing conformational change of T7 RNA polymerase and DNA complex by solid-state nanopores

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Chinese Physics B 2018年第11期27卷 659-664页

作者： Xm Tong Rui Hu Xiaoqing Li Qing Zhao State Key laboratory for Mesoscopic Physics and electron microscopy laboratory School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

Proteins are crucial to most biological processes, such as enzymes, and in various catalytic processes a dynamic motion is required. The dynamics of protein are embodied as a conformational change, which is closely related to the flexibility of protein. Recently, nanopore sensors have become accepted as a low cost and high throughput method to study the features of proteins. In this article, we used a SiN nanopore device to study the flexibility of T7 RNA polymerase（RNAP） and its complex with DNA promoter. By calculating full-width at half-maximum（FWHM） of Gaussian fits to the blockade histograms, we found that T7 RNAP becomes more flexible after binding DNA promoter. Moreover, the distribution of fractional current blockade suggests that flexibility alters due to a breath-like change of the volume.

关键词： solid-state nanopore T7 RNA polymerase conformational change protein flexibility

Unusual relationship between impact toughness and grain size in a high-manganese steel

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Journal of Materials Science & Technology 2021年第30期89卷 122-132页

作者： Pan Xie Shucheng Shen Cuilan Wu Jiehua Li Jianghua Chen Center for High Resolution electron microscopy College of Materials Science and EngineeringHunan UniversityChangsha410082China Institute of Casting Research Montanuniversität LeobenA-8700LeobenAustria

The high-manganese steels are important structural materials,owing to their excellent toughness at low ***,the microstructural causes for their unusual properties have not adequately been understood thus ***,we report a reversal relationship between impact toughness and grain size in a high-manganese steel and its unrevealed microscopic mechanisms,which result in an excellent low-temperature toughness of the *** investigations show that with increasing grain size the impact toughness of the steel can be improved drastically,especially at *** electron microscopy characterization reveals that the enhanced impact toughness of the coarse-grained steel is attributed to the twinning induced plasticity and transformation induced plasticity effects,which produce large quantities of deformation twins,ε_(hcp)-martensite andα'_(bcc)-***,in the fine-grained steels,the formation of deformation twins and martensite is significantly inhibited,leading to the decrease of impact *** characterizations also indicate thatε_(hcp)-martensite becomes more stable thanα'_(bcc)-martensite with decreasing temperature,resulting in characteristic microstructures in the coarse-grained samples after impact deformation at liquid nitrogen *** the coarse-grained samples under impact deformation at-80℃,ε_(hcp)-martensite transformation,α'_(bcc)-martensite transformation and deformation twinning all occur simultaneously,which greatly improves the toughness of the steel.

关键词： Toughness Grain size Twinning induced plasticity Transformations induced plasticity High-manganese steel

DETECTION OF PLATELET-DERIVED MICROPARTICLES USING FLOW CYTOMETRY AND ITS CLINICAL APPLICATION

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Chinese Medical Sciences Journal 2003年第1期18卷 26-30页

作者：崔巍马文新林其燧韩晔华 Department of Clinical laboratory Peking Union Medical College HospitalElectron-microscopy Laboratory Basic Medical Institute

*** establish a flow cytometric internal standard method for counting platelet-derived microparti-cles(PMPs)and to study its clinical significance. Methods. PMPs suspension(platelet poor plasma,PPP) was extracted by gradual centrifugation. According to the size of PMPs,3 μm and 0.8μm latex beads were used as internal standards for the quantitation. PMPs were counted by adjusting flow cytometric discrimination and voltage of forward scatter and side scatter. Results. In 30 healthy donors,the average concentration of resting PMPs was(1.2×105±5.7×104 )/ml and that of activated PMPs was(1.6×106±9.1×105)/ml. Compared with healthy donors,PMPs mean value was significantly higher(P0.05)] .Conclusions. PMPs is a useful indicator in monitoring platelet activation,and plays an important role in thrombotic disease. By flow cytometric internal standard method,PMPs can be counted rapidly and accurately,which may be very helpful in interlaboratory comparative studies.

关键词： platelet microparticles platelet activation flow cytometry

Current Induced Non-Volatile Resistive Switching Effect in Silicon Devices with Large Magnetoresistance

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Chinese Physics Letters 2014年第7期31卷 156-159页

作者：王集敏章晓中朴红光罗昭初熊成悦 Key laboratory of Advanced Materials (MOE) School of Materials Science and Engineering Tsinghua University Beijing 100084 National Center for electron microscopy (Beijing) Tsinghua University Beijing 100084

We develop a non-volatile resistive switching device in a Si-SiO2-Mg structure with an on/off ratio of about 4.5 at a certain transition voltage after being stimulated by a large current. It is observed that the resistance transition voltage Vt shifts reproducibly under a reversed large current. By applying a reading voltage in the range of Vt, non-volatile resistive switching phenomena with an endurance of more than 80 cycles are observed. Moreover, it is also found that the magnetic field could shift Vt to higher values, yielding a voltage dependent room-temperature magnetoresistance in the range of 10^3 % at 1 T. The multifunctional properties of the silicon device suggested by this work may be beneficial to the silicon based industry.

关键词： Magnetoresistance

Ag/graphene composite based on high-quality graphene with high electrical and mechanical properties

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Progress in Natural Science:Materials International 2019年第4期29卷 384-389页

作者： Yanpeng Yang Yunjie Ping Youning Gong Zhongchi Wang Qiang Fu Chunxu Pan Suzhou Institute Wuhan University School of Physics and Technology MOE Key Laboratory of Artificial Micro-and Nano-structures Wuhan University Center for electron microscopy Wuhan University

A simple and effective process has been reported to prepare the silver(Ag)/graphene composite with excellent mechanical and electrical properties based on high-quality graphene(HQG).The HQG was fabricated via hot pressing of reduced graphene oxide(RGO) from chemical exfoliation,while the Ag/HQG composite was obtained by using spark plasma sintering(SPS) treatment under high temperature(1500℃) and moderate pressure(40 MPa).With low oxygen-containing functional groups and defect density,the HQG dispersed homogeneously in the composite after high-energy ball *** comparison to pure Ag,the as-prepared Ag/RGO composite exhibited a great enhancement of 11% electrical conductivity and 42% micro-hardness with an optimal RGO adding content(1 wt%).The Ag/HQG composite is expected to open up a new way for the novel Ag-based electrical contact materials,and further to broaden its applications in micro-electronics and switching power.

关键词： Graphene Silver Composite Electrical property Mechanical property

Collagen Fibers in Crocodile Skin and Teeth:A Morphological Comparison Using Light and Scanning electron microscopy

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Journal of Bionic Engineering 2020年第4期17卷 669-676页

作者： Piotr Krzysztof Szewczyk Urszula Stachewicz Metals Engineering and Industrial Computer Science and International Centre of electron microscopy for Materials Science AGH University of Science and TechnologyKraków 30-059Al.Mickiewicza 30Poland

Collagen is one of the most versatile tissues of living organisms that comes in many shapes and sizes,providing functions ranging from tissue matrix through,ligament formation up to enabling mineralization in *** detailed light microscopy and Scanning electron microscopy(SEM)observations conducted in this study,allowed us to investigate morphology,sizes and crimp patterns of collagen fibers observed in crocodile skin and ***,the microscopy study revealed that although two completely different tissues were investigated,many similarities in their structure based on collagen fibers were *** type I is present in crocodile skin and teeth,showing the flexibility in naturally constructed tissues to obtain various *** crimp size investigation of collagen fibers confirmed experimentally the theoretical 67 nm D-periodicity expected for collagen type *** collagen in teeth provides a matrix for crystal growth and in the skin provides flexibility and is a precursor for corneous ***,these observations of the collagen in the skin and tooth structure in crocodiles play an important role in designing biomimetic materials with similar functions and properties.

关键词： crocodile skin collagen crimp fiber crocodile tooth SEM

Synthesis of graphitic carbon nitride through pyrolysis of melamine and its electrocatalysis for oxygen reduction reaction

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Chinese Chemical Letters 2013年第2期24卷 103-106页

作者： He-Sheng Zhai Lei Cao Xing-Hua Xia Center for Scanning electron microscopy Xiamen University State Key laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering.Nanjing University

Received 2 December 2012 Received in revised form 26 December 2012 Accepted 31 December 2012 Available online 4 February 2013

关键词： Melamineg-C3N4Oxygen reduction reactionElectrocatalysis

A Novel Process for High-efficient Synthesis of One-dimensional Carbon Nanomaterials from Flames

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Journal of Materials Science & Technology 2008年第4期24卷 603-607页

作者： XianG QI Jun ZHANG Chunxu PAN Department of Physics and Key laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education Wuhan University Wuhan 430072 China Center for electron microscopy Wuhan University Wuhan 430072 China

The substrate pre-treatment plays a key role in obtaining hollow-cored carbon nanotubes （CNTs） and solid-cored carbon nanofibers （CNFs） from flames. This paper introduces a simply and high-efficient process by coating a NiSO4 or FeSO4 layer on the substrate as catalyst precursors. Comparing with the regular pre-treatment methods, the present experiments showed that the coating pre-treatment provided the following advantages： 1） greatly shortening the synthesis time; 2） available variant substrates and carbon sources; 3） narrowing the diameters distribution. The sulfate is considered to be a crucial factor at the growth of CNTs and CNFs, because it increases the surface energy of catalyst particles and the surface specificity of sulfurs action in metallic grains. This novel process provides a possibility for high quality and mass production of CNTs and CNFs from flames.

关键词： Carbon nanotubes Carbon nanofibers Flames Sulfate

Microstructure and formation mechanism of twins of laths of austenite with high nitrogen

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Science China(Technological Sciences) 2007年第6期50卷 755-764页

作者： WU CuiLan1,2 & LUO ChengPing2 1 Center for High Resolution electron microscopy, College of Materials Science and Engineering, Hunan University, Changsha 410082, China 2 College of Mechanical Engineering, South China University of Technology, Guangzhou 510641, China Center for High Resolution electron microscopy College of Materials Science and Engineering Hunan University Changsha China College of Mechanical Engineering South China University of Technology Guangzhou China

The microstructure of composite diffusion layer of the nitrided and chromized 0.2% carbon steel is investigated using TEM and EDS. It is found that laths of austenite with high nitrogen (γ N) precipitate from α-ferrite matrix in the deeper zone of the diffusion layer. These γ N laths are all twins, with their {111} twinning planes parallel to the lath axis, thus forming a characteristic "back-to-back" morphology. There are two types of γN lath. The first is a genuinely {111} twin, and γ N and α keep the accurate K-S relationship, and each γ N and α form a sharp and smooth γ N/α inter- face of {335}γN//{341}α, namely habit plane {335}fcc. The second is a pseudo-twin, with micro-twins {111} or faults formed within the two twin components. Localized lattice deformation (relaxation) seems to have occurred at the interfaces of the second type of γ N due to the formation of micro-twins or faults within the twin components. These micro-twins or faults make the orientation relationship (OR) between each of the γN and the α-matrix deviate from the accurate K-S OR, and the OR between two γ N twin components deviate from the genuine {111} twin relation- ship. In addition, the γ N/α interface of the second type of γ N is not as sharp or smooth as that of the first one.

关键词： austenite containing nitrogen, twins, steel 20, nitriding, composite chromizing