检索结果-南通市图书馆

Nano Research 2024年第4期17卷 2555-2562页

作者： Guangyuan Yan Tianlu Wang Biwei zhao Wenjing Gao Tong Wu Liming ou School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Medium-entropy oxides(MEOs)with broad compositional tunability and entropy-driven structural stability,are receiving booming attention as a promising candidate for oxygen evolution reaction(OER)***,ultrathin two-dimensional(2D)nanostructure offers extremely large specific surface area and is therefore considered to be an ideal catalyst ***,it remains a grant challenge to synthesize ultrathin 2D MEOs due to distinct nucleation and growth kinetics of constituent multimetallic elements in 2D anisotropic *** this work,an ultrathin 2D MEO(MnFeCoNi)O was successfully synthesized by a facile and low-temperature ionic layer epitaxy *** from multi-metal synergistic effects within ultrathin 2D nanostructure,this 2D MEO(MnFeCoNi)O revealed excellent OER electrocatalytic performance with a quite low overpotential of 117 mV at 10 mA·cm^(-2) and an impressive stability for 120 h continuous operation with only 6.9%***,the extremely high mass activity(5584.3 A·g^(-1))was three orders of magnitude higher than benchmark RuO_(2)(3.4 A·g^(-1))at the same overpotential of 117 *** work opens up a new avenue for developing highly efficient and stable electrocatalysts by creating 2D nanostructured MEOs.

关键词： medium-entropy oxide two-dimensional nanomaterials ionic layer epitaxy oxygen evolution reaction electrocatalysis

An analytical solution for the elastic fields near spheroidal nano-inclusions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第6期25卷 821-830页

作者： z. Y. ou G. F. Wang T. J. Wang Department of Engineering Mechanics,MOE Key Laboratory for Strength and Vibration,Xi’an Jiaotong University, Xi’an 710049, China Department of Engineering Mechanics MOE Key Laboratory for Strength and Vibration Xi’an Jiaotong University Xi’an 710049 China

When the size of an inclusion shrinks to nanometers, interface energy plays an important role in the deformation around it. In the present paper, we consider the effect of interface energy on the elastic fields near a spheroidal nanoinclusion embedded in an elastic medium on the basis of surface elasticity theory. Using Boussinesq-Sadowsky potential function method, we obtain the deformation field near the inclusion subjected to a uniformly uniaxial loading at infinity. The results show that the elastic fields near the nano-inclusion depend strongly on the interface properties, the size and shape of inclusion. These new characteristics may be helpful to understand various relevant mechanical performances of nanosized inhomogeneities.

关键词： Interface energy .Elastic fields .Inhomogeneity - Nanometer

Yaw attitude of eclipsing GPS satellites and its impact on solutions from precise point positioning

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第32期55卷 3687-3693页

作者： zHANG BaoCheng ou JiKun YUAN YunBin zHONG ShiMing Key Laboratory of Dynamic Geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

During the period when a GPS satellite,the Earth and the Sun are approximately collinear,the phenomenon of eclipsing the satellite occurs,when the satellite yaw attitude deviates from its nominal case,i.e. the body X-axis cannot point towards the Sun for Block II&IIA or away from it for Block IIR satellites. The yaw attitude of the eclipsing satellites has a significant influence on both the satellite clock estimation at each International GNSS Service (IGS) Analysis Center (AC) and for users of the precise point positioning (PPP) implementations. It is known that,during the eclipsing periods,inconsistent yaw attitude models among the ACs will contribute to the errors of the IGS combined clock products. As for the PPP user,the influence of the eclipsing satellite is two-fold. First,as the satellite clocks are always kept fixed during PPP implementation,the above-mentioned problematic IGS clocks will inevitably be passed on to the PPP estimates. Second,the improper yaw attitude modeling of the eclipsing satellite will cause a correction bias exceeding 1 dm for the two kinds of attitude-related systematic errors,namely the phase wind-up and satellite antenna phase center offset,which will further deteriorate the accuracy of the PPP solutions. A yaw attitude model is introduced in this paper with the aim of improving the reliability of PPP solutions during the satellite eclipsing period.

关键词： GPS卫星偏航单点定位姿态全球导航卫星系统卫星时钟购买力 IGS

Heat dissipation of carbon shell in zrC-SiC/TaC coating to improve protective ability against ultrahigh temperature ablation

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第7期13卷 1080-1091页

作者： Yuyu zhang Xuemeng zhang Hongkang ou Bozhe Wang Jia Sun Qiangang Fu Science and Technology on Thermostructural Composite Materials Laboratory Shaanxi Key Laboratory of Fiber Reinforced Light-Weight CompositesNorthwestern Polytechnical UniversityXi’an 710072China System Design Institute of Hubei Aerospace Technology Academy Wuhan 430040China

To efficiently decrease ablation heat accumulation and improve the ability of zrC-SiC/TaC coatings to protect carbon/carbon(C/C)composites,a thermally conductive nanonetwork with a ceramic@carbon core-shell structure was designed and ***-derived SiC/TaC with a graphene carbon shell was synthesized and introduced into a zrC coating by supersonic atmospheric plasma spraying(SAPS).Graphene shell paths increased the heat transfer capability by lowering the surface temperature to approximately 200℃during oxyacetylene *** heat dissipation of the graphene shell in the zrC-SiC/TaC@C coating reduced the volatilization of low-melting-point phases and delayed the sintering of zrO_(2) ***,the graphene shell in zrC-SiC/TaC@C coating decreased the mass and linear ablation rates by 91.4%and 93.7%compared to zrC-SiC/TaC coating,*** work provided a constructive idea for improving the ablation resistance of the coatings by incorporating carbon nanomaterials as a function of heat dissipation.

关键词： carbon/carbon(C/C)composites carbon nanomaterials core-shell structure polymer-derived ceramic(PDC) ablation resistance

Single-structure 3-axis Lorentz force magnetometer based on an AlN-on-Si MEMS resonator

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2024年第3期10卷 75-86页

作者： Cheng Tu Xu-heng ou-Yang Ying-jie Wu Xiao-sheng zhang School of Integrated Circuit Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

This work presents a single-structure 3-axis Lorentz force magnetometer(LFM)based on an AlN-on-Si MEMS *** operation of the proposed LFM relies on the flexible manipulation of applied excitation currents in different directions and frequencies,enabling the effective actuation of two mechanical vibration modes in a single device for magnetic field measurements in three ***,the excited out-of-plane drum-like mode at 277 kHz is used for measuring the x-and y-axis magnetic fields,while the in-plane square-extensional mode at 5.4 MHz is used for measuring the z-axis magnetic *** different configurations of applied excitation currents ensure good crossinterference immunity among the three *** to conventional capacitive LFMs,the proposed piezoelectric LFM utilizes strong electromechanical coupling from the AlN layer,which allows it to operate at ambient pressure with a high *** understand and analyze the measured results,a novel equivalent circuit model for the proposed LFM is also reported in this work,which serves to separate the effect of Lorentz force from the unwanted capacitive *** demonstrated 3-axis LFM exhibits measured magnetic responsivities of 1.74 ppm/mT,1.83 ppm/mT and 6.75 ppm/mT in the x-,y-and z-axes,respectively,which are comparable to their capacitive counterparts.

关键词： resonator Lorentz structure

A Novel Method for the Synthesis of Bioactive Benzimidazolyl-Phenoxyacetic Acid O-Acetylglucosyl Saccharide Esters

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2006年第2期11卷 419-422页

作者： CHEN Hong CHEN Yunhua ou Chunyan HUANG Siqing Department of Applied Chemistry Guangdong Ocean University Zhanjiang 524088 Guangdong China Department of Chemistry Nanchang University Nanchang 330047 Jiangxi China

A novel method of synthesis of nitro or trifluoromethyl substituted benzimidazolyl phenoxyacetic acid O-acetylglucosyl saccharide esters by the reaction of O-acetylglucosyl bromide with substituted benzimidazolyl phenoxyacetic acid at room temperature was developed. 4 dimethylaminopyridine （DMAP） was used as catalyst, triethylamine （Et3N） was used as deacid reagent, three saccharide esters were synthesized in the system of DMAP/ Et3 N. The catalytic mechanism of DMAP/Et3N was discussed. The results show that DMAP is an effective catalyst, the yields can reach 50%. The test indicates that the title compounds show better antiplantviral activity.

关键词： Saccharide Estersbenzimidazolyl-phenoxyacetic acid O-acetylglucosyl saecharide ester antiplantviral activity DMAP/Et3N

Oxidation Behavior of K4750 Alloy at Temperatures Between 750°C and 1000°C

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2021年第12期34卷 1657-1668页

作者： Yan-Li Liu Kun-Lei Hou Mei-Qiong ou Ying-Che Ma Kui Liu School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

This study investigated the oxidation behavior of a new casting Ni-based superalloy K4750 at 750°C-1000°C in air for 100 h-1000 h by isothermal oxidation *** oxidation-kinetic curves were plotted by the static discontinuous weight gain *** and identification of oxidation products were conducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),electron probe micro-analysis(EPMA)and X-ray diffraction(XRD).X-ray photoelectron spectrometer(XPS)was also used to analyze the chemical state of elements and the distribution in *** results showed that the oxidation-kinetic curves of K4750 alloy basically obeyed the parabolic *** average oxidation rate below 900°C was less than 0.1 g/m 2·h which meant the alloy was at a complete anti-oxidation grade,and the alloy was at an anti-oxidation grade at 1000°*** predominant surface oxide was Cr_(2)O_(3),and a double layer structure of the oxide scale was observed at all tested temperatures as time *** outer oxide layer contained continuous Cr_(2)O_(3)and a small amount of oxides mixed TiO2 and NiCr2O4,while the inner oxide layer was composed with Al_(2)O_(3).The oxidation process could be interpreted by the competitive oxidation of different *** diffusion rate of Ti through Cr_(2)O_(3)layer increased with increasing temperature,and thus the generation of TiO2 was *** dispersed TiO2 reaching a certain amount destroyed the continuity of the surface oxide layer,which accounted for the reduction of oxidation resistance of K4750 alloy at high temperatures.

关键词： Ni-based superalloy Oxidation Titanium Internal oxides

Modeling and optimal design of multilayer thermal cantilever microactuators

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第5期52卷 1167-1170页

作者： FU JianYu CHEN DaPeng YE TianChun JIAO BinBin ou Yi Silicon Device and Integration Technology Department Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029China

A model of curvature and tip deflection of multilayer thermal cantilever actuators is *** sim-plified expression received from the model avoids inverting complex matrices enhances understanding and makes it easier to optimize the structure *** is performed,the modeled and experimental results demonstrate the validity of the model,and it also indicates that Young's module makes great contribution to the deflection;therefore,thin layers cannot be ignored arbitrarily.

关键词： thermal microactuator tip deflection multilayer model optimization

Material Removal Characteristics of Single-Crystal 4H-SiC Based on Varied-Load Nanoscratch Tests

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2023年第4期36卷 125-138页

作者： Kun Tang Wangping ou Cong Mao Jie Liang Moke zhang Mingjun zhang Yongle Hu Hunan Provincial Key Laboratory of Intelligent Manufacturing Technology for High-performance Mechanical Equipment Changsha University of Science and TechnologyChangsha 410114China

Single-crystal silicon carbide(SiC)has been widely applied in the military and civil fields because of its excellent physical and chemical ***,as is typical in hard-to-machine materials,the good mechanical properties result in surface defects and subsurface damage during precision or ultraprecision *** this study,single-and double-varied-load nanoscratch tests were systematically performed on single-crystal 4H-SiC using a nanoindenter system with a Berkovich *** material removal characteristics and cracks under different planes,indenter directions,normal loading rates,and scratch intervals were analyzed using SEM,FIB,and a 3D profilometer,and the mechanisms of material removal and crack propagation were *** results showed that the Si-plane of the single-crystal 4H-SiC and edge forward indenter direction are most suitable for material removal and *** normal loading rate had little effect on the scratch depth,but a lower loading rate increased the ductile region and critical depth of ***,the crack interaction and fluctuation of the depth-distance curves of the second scratch weakened with an increase in the scratch interval,the status of scratches and chips changed,and the comprehensive effects of the propagation and interaction of the three cracks resulted in material fractures and chip *** calculated and experimental values of the median crack depth also showed good consistency and ***,this study provides an important reference for the high-efficiency and precision machining of single-crystal SiC to ensure high accuracy and a long service life.

关键词： Single crystal silicon carbides Varied-load nanoscratch Material removal Crack propagation

Dietary nutrient status modulates nutrient regeneration in the marine ciliate Euplotes vannus

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2023年第11期42卷 81-89页

作者： Xuejia He zhang Lu Weijie Chen zhen Shi Linjian ou Ren Hu College of Life Science and Technology and Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes Jinan UniversityGuangzhou 510000China South China Sea Institute of Oceanology Chinese Academy of ScienceGuangzhou 510000China Institute of Hydrobiology Jinan UniversityGuangzhou 510000China

Marine ciliates play important roles not only in linking the microbial loop to the classic pelagic and benthic food chains but also in regenerating nutrients,yet how dietary nutrient imbalance impacts their nutrient regeneration has not been thoroughly *** growth and physiological responses of Euplotes vannus to low dietary nitrogen(LN)and low dietary phosphorus(LP)conditions were studied,with the bacterium Pseudomonas putida as *** on LN prey reduced the growth rate of *** nutrient limitation changed the types and quantities of nutrient *** on LP prey enhanced dissolved organic carbon excretion but reduced orthophosphate excretion,whereas feeding on LN prey generally resulted in decreases in the excretion rate in all N forms(ammonium,urea,and nitrate).In addition,the proportion of ammonium in regenerated N increased significantly under the LN *** findings indicate that a nutrient-imbalanced diet triggers *** to retain limited macronutrients and promotes the recycling of excessive macronutrients,which may potentially form positive and negative feedback to ambient N and P limitations,respectively.

关键词： protist excretion bacteria microbial loop nutrient regeneration