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Contributions of optimized tensor interactions on the binding energies of nuclei 预览
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作者 Di Wu Chun-Lin Bai +2 位作者 H.Sagawa Zeng-Qiang Song Huan-Qiao Zhang 《核技术:英文版》 SCIE CAS CSCD 2020年第2期11-19,共9页
The tensor parts of Skyrme interactions are constrained from the collective charge-exchange spin-dipole and Gamow-Teller excitation energies in 90Zr and 208Pb,together with the isotopic dependence of energy splitting ... The tensor parts of Skyrme interactions are constrained from the collective charge-exchange spin-dipole and Gamow-Teller excitation energies in 90Zr and 208Pb,together with the isotopic dependence of energy splitting between proton h11=2 and g7=2 single-particle orbits along the Z=50 isotopes.With the optimized tensor interactions,the binding energies of spherical or weakly deformed nuclei with A=54-228 are studied systematically.The present results show that the global effect of tensor interaction is attractive and systematically increases the binding energies of all these nuclei and makes the nuclei more bound.The root mean squared deviation of the calculated binding energies from the experimental values is significantly improved by the optimized tensor interactions,and the contribution of the tensor interaction to the binding energy is estimated. 展开更多
关键词 Tensor force Binding energy Gamow-Teller transition Spin-dipole transition Single-particle energy differences
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Nanoparticle Dispersion and Glass Transition Behavior of Polyimide-grafted Silica Nanocomposites
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作者 Sha-Ni Hu Yu Lin Guo-Zhang Wu 《高分子科学:英文版》 SCIE CAS CSCD 2020年第1期100-108,I0008,共10页
How to control the spatial distribution of nanoparticles to meet different performance requirements is a constant challenge in the field of polymer nanocomposites.Current studies have been focused on the flexible poly... How to control the spatial distribution of nanoparticles to meet different performance requirements is a constant challenge in the field of polymer nanocomposites.Current studies have been focused on the flexible polymer chain systems.In this study,the rigid polyimide(PI) chain grafted silica particles with different grafting chain lengths and grafting densities were prepared by "grafting to" method,and the influence of polymerization degree of grafted chains(N),matrix chains(P),and grafting density(a) on the spatial distribution of nanoparticles in the PI matrix was explored.The glass transition temperature(Tg) of PI composites was systematically investigated as well.The results show that silica particles are well dispersed in polyamic acid composite systems,while aggregation and small clusters appear in PI nanocomposites after thermal imidization.Besides,the particle size has no impact on the spatial distribution of nanoparticles.When σ·N0.5<<(N/P)2,the grafted and matrix chains interpenetrate,and the frictional resistance of the segment increases,resulting in restricted relaxation kinetics and Tg increase of the PI composite system.In addition,smaller particle size and longer grafted chains are beneficial to improving Tg of composites These results are all propitious to complete the microstructure control theory of nanocomposites and make a theoretical foundation for the high performance and multi-function of PI nanocomposites. 展开更多
关键词 Polyimide grafted nanoparticle Dispersion morphology Glass transition temperature
三峡库区山区农业生态系统转型
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作者 梁鑫源 李阳兵 +1 位作者 邵景安 冉彩虹 《地理学报:英文版》 SCIE CSCD 2020年第2期281-296,共16页
The Three Gorges Reservoir Area(TGRA)is typical of an ecologically vulnerable area,comprised of rural and mountainous areas,and with high immigration.Because of its economic and ecologic importance,studying the tradit... The Three Gorges Reservoir Area(TGRA)is typical of an ecologically vulnerable area,comprised of rural and mountainous areas,and with high immigration.Because of its economic and ecologic importance,studying the traditional agroecosystem changes in the TGRA is key to rural development and revitalization.In this study,we apply a framework of theoretical analysis,empirical study,and trend prediction to the Caotangxi River watershed within the TGRA.Using QuickBird high-resolution remote sensing images from 2012 to 2017 to evaluate natural resources and farmers’behavior,we analyze the transition and trends in the traditional agroecosystem in mountainous areas of the TGRA at spatial scale of the man-land relationship.We find that the agroecosystem in the TGRA can be divided into four modes using 100 m interval buffer rings:high-low-low,high-low-high,low-high-low and low-low-high mode where the different modes represent the agricultural development stages in the TGRA.Furthermore,the traditional agroecosystem in TGRA,represented by system elements such as farmers and sloping farmland,is transforming to accommodate the diversification of farmer livelihoods.For example,sloping farmland,which was dominated by a production function,now has equal emphasis on ecological and economic functions.Spatially,the range of the agroecosystem transition has migrated beyond high mountain areas to flat valley areas.Generally,this study provides an overview of land use in rural areas,controls on soil and water loss in mountainous areas,and better rural living environments in the TGRA. 展开更多
关键词 Three Gorges Reservoir Area ecologically fragile area mountainous area traditional agroecosystem transition empirical study spatial scale
比较传媒体制研究中的归类与遮蔽问题--以有关埃及传媒体制的知识生产为例
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作者 白洪谭 赵月枝 《新闻界》 CSSCI 北大核心 2020年第1期82-91,共10页
在美国传播学者不同阶段的论著中,1956-2004年间的埃及传媒体制先后被归类于威权主义媒体、动员型媒体和转型性媒体。然而,这一系列分类并非价值中立,而是暗含权力和价值取向,是埃及被纳入现代世界秩序与文明等级的一个缩影。梳理原始... 在美国传播学者不同阶段的论著中,1956-2004年间的埃及传媒体制先后被归类于威权主义媒体、动员型媒体和转型性媒体。然而,这一系列分类并非价值中立,而是暗含权力和价值取向,是埃及被纳入现代世界秩序与文明等级的一个缩影。梳理原始文献不仅可以发现西方传播学者对埃及传媒体制归类的谬误之处,还可以发现这些学者关于西方传媒体制的道德优越感和他们所持的单一线性历史观在知识生产过程中的渗透。再现归类埃及媒体的知识生产情境,不仅可以以此为例对西方媒体分类体系进行祛魅,而且可以在知识"深度去西方化"的背景下"打捞"被遮蔽的"另类媒体",讲好全球历史中的媒体变迁故事;更重要的是,这有助于我们超越方法论民族主义,在跨文化传播政治经济学的框架下重新确立书写全球传播史的马克思主义史观,进而认识到历史进程的开放性与另类可能性。 展开更多
关键词 埃及 传媒体制 威权主义 动员 转型
Effects of epidermal growth factor on transforming growth factor-beta1-induced epithelial-mesenchymal transition and potential mechanism in human corneal epithelial cells
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作者 Shu-Yang Chen Chen Xie +1 位作者 Hong Zhu Ye Shen 《国际眼科杂志:英文版》 SCIE CAS 2020年第1期11-20,共10页
AIM: To evaluate the effects of epidermal growth factor(EGF) on transforming growth factor-beta1(TGF-β1)-induced epithelial-mesenchymal transition(EMT) in human corneal epithelial cells(HCECs). METHODS: HCECs were cu... AIM: To evaluate the effects of epidermal growth factor(EGF) on transforming growth factor-beta1(TGF-β1)-induced epithelial-mesenchymal transition(EMT) in human corneal epithelial cells(HCECs). METHODS: HCECs were cultured and treated with TGF-β1 for establishing the model of EMT in vitro. Biological effect of EGF on TGF-β1-induced EMT was evaluated. Proteins and m RNAs expression changes of E-cadherin, N-cadherin and Fibronectin(EMT-relative markers) after TGF-β1 or TGF-β1 combined EGF treatment were detected by Western blot and RT-PCR, respectively. Viability and migration of HCECs were measured by CCK-8, transwell cell migration assay and cell scratch wound healing assay. Activation of Smad2, ERK, p38, JNK and Akt signaling pathways were evaluated by Western blot. Inhibitors of relevant signaling pathways were added to the HCECs to explore the key signal mechanism.RESULTS: With treatment of TGF-β1 only, three EMTrelative proteins and m RNA expression showed that EMT up-regulated in a concentration-dependent and time-dependent manner, with significantly decreasing cell viability(TGF-β1≥5 ng/m L, P<0.05) and increasing cell migration(TGF-β1≥5 ng/m L, P<0.01). The phosphorylation of Smad2 and p38 was a key process of TGF-β1-induced EMT. Meanwhile, EMT-relative proteins and m RNA expression showed that EGF inhibited TGF-β1-indued EMT, with significantly increasing cell viability(EGF≥10 ng/m L, P<0.01). It was noteworthy that EGF significantly enhanced cell migration although EMT was inhibited(EGF≥10 ng/m L, P<0.01), and the blockage of p38(by SB202190, a p38 inhibitor) was a potential mechanism of this phenomenon. CONCLUSION: EGF inhibits TGF-β1-induced EMT via suppressive p38, and promotes cells proliferation and migration in a non-EMT process by inhibiting p38 pathway. 展开更多
关键词 epidermal growth factor P38 epithelialmesenchymal transition corneal epithelial cell
Construction of Characteristic Towns in Suburban Areas 预览
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作者 XU Zhunheng 《景观研究:英文版》 2020年第1期36-38,共3页
The policy background of the construction of characteristic towns in China and the spatial characteristics of suburban towns were studied.The opportunities and challenges of the construction of characteristic towns in... The policy background of the construction of characteristic towns in China and the spatial characteristics of suburban towns were studied.The opportunities and challenges of the construction of characteristic towns in the suburbs under the background of new urbanization were discussed.And appropriate planning strategy for the construction of characteristic towns in the suburbs was explored. 展开更多
关键词 SUBURB Characteristic towns Spatial transition
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从玻尔假说到发光原理 预览
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作者 赵丽娟 《大学物理》 2020年第1期5-8,13,共5页
光是电磁波,发光即产生电磁波或光辐射,发光物理是发光材料创新设计和应用的理论基础.本文从玻尔假说出发,通过分析真空中和非真空中的孤立原子的能级和各类跃迁阐述发光的基本原理,通过分析非孤立原子激发态的能量传递阐述量子剪裁发... 光是电磁波,发光即产生电磁波或光辐射,发光物理是发光材料创新设计和应用的理论基础.本文从玻尔假说出发,通过分析真空中和非真空中的孤立原子的能级和各类跃迁阐述发光的基本原理,通过分析非孤立原子激发态的能量传递阐述量子剪裁发光和上转换发光物理机制,通过介绍与发光有关的诺贝尔奖让学生了解该领域的最新进展,实现大学物理教学中从基础到前沿的跨越. 展开更多
关键词 能级 跃迁 激发态的能量传递 上转换发光 量子剪裁发光
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Artificially induced sex-reversal leads to transition from genetic to temperature-dependent sex determination in fish species
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作者 Yang Xiong Shuai Wang +1 位作者 Jian-Fang Gui Jie Mei 《中国科学:生命科学英文版》 SCIE CAS CSCD 2020年第1期157-159,共3页
Dear Editor,Sex determination is highly plastic across vertebrates.The mechanisms of sex determination can be broadly divided into genetic sex determination(GSD)and environmental sex determination(ESD).GSD is the most... Dear Editor,Sex determination is highly plastic across vertebrates.The mechanisms of sex determination can be broadly divided into genetic sex determination(GSD)and environmental sex determination(ESD).GSD is the most popular sex-determining type in vertebrates,while ESD mainly occurred in some fish and reptiles(Li and Gui,2018a,2018b).Sex determination in teleost fish is usually controlled by the interaction between genetic and environmental factors(Mei and Gui,2015).Naturally,the coexistence of GSD and ESD(temperature・dependent sex determination)was found in several fish species including gibel carp(Carassius gibelio)and half-smooth tongue sole(Cynoglossus semilaevis)(Li and Gui,2018b),as well as in bearded dragon(Pogona vitticeps)(Holleley et al.,2015).However,the exact mechanism of transition between GSD and ESD is unclear. 展开更多
关键词 determination FISH TRANSITION
Synthesis, Spectroscopic Characterization and ThermogravimetricAnalysis of Cr(Ⅱ), Cu(Ⅱ), Zn(Ⅱ) and Mg( Ⅱ), Captopril Coordination Compounds 预览
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作者 Asma SAl-Wasidi Nawal MAl-Jafshar +4 位作者 Amal MAl-Anazi Ahmed M.Naglah Robson Fde Farias Claudio Airoldi Moamen SRefat 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2020年第2期661-664,共4页
In this work,we have reported the synthesis and spectroscopic characterization of captopril(Cap)coordination compounds:Cu(Cap)·2H 2O,Cr(Cap)·H 2O,Zn(Cap)·3H 2O and Mg(Cap)4.Herein,it is worthily mention... In this work,we have reported the synthesis and spectroscopic characterization of captopril(Cap)coordination compounds:Cu(Cap)·2H 2O,Cr(Cap)·H 2O,Zn(Cap)·3H 2O and Mg(Cap)4.Herein,it is worthily mentioned that the FTIR spectroscopic technique was employed to recognized the nature of coordination between captopril ligand and copper,chromium,zinc and magnesium(Ⅱ)metal ions.In view of the infrared spectroscopic tool,the copper(Ⅱ)metal ion coordinated toward captopril drug ligand through sulfur atom of SH group dependent on the absent of stretching vibration band of—SH.Based on this result,the stretching motion ofνa(COO)shifts clearly indicates that Cu 2+,Cr 2+,Zn 2+and Mg 2+the carboxylic group is employed as coordinative site for all compounds as a metal-ligand coordinative bond.As a general behavior,it is verified that the coordination compound thermal stability(considering the release of captopril molecules,not the release of water molecules)is affected by the metal cation radius:minor radius is associated with higher thermal stability,probably due to a higher metal-captopril bond dissociation enthalpy. 展开更多
关键词 CAPTOPRIL Transition metals SPECTROSCOPY Coordination compounds THERMOGRAVIMETRY
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General Model of Temperature-dependent Modulus and Yield Strength of Thermoplastic Polymers
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作者 Ping-Yuan Huang Zhan-Sheng Guo Jie-Min Feng 《高分子科学:英文版》 SCIE CAS CSCD 2020年第4期382-393,I0007,共13页
A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers.This model,which depends on only two parameters with clear and specific physical meanin... A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers.This model,which depends on only two parameters with clear and specific physical meanings,can describe the temperaturedependent modulus and yield strength of thermoplastic polymers over the full glass transition region.The temperature-dependent modulus and yield strength of three thermoplastic polymers were measured by uniaxial tension tests over a temperature range of 243-383 K.The predictions showed excellent agreement with the experimental data.Sensitivity analysis of model input parameters showed negligible effect on the present general model.The universality of the present general model was further validated,showing excellent agreement with published experimental data on other thermoplastic polymers and their composites. 展开更多
关键词 Thermoplastics MODULUS Yield strength MODELING Glass transition
Jianpi Bushen Recipe affects epithelial-mesenchymal transition in hepatocellular carcinoma through TGF-β and Twist 预览
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作者 Hong-Jie Liu You—Ying Lai +2 位作者 Zhi-Fen Han Jian-Jie Chen Xin-Wen Ma 《药物联合治疗》 2020年第1期1-6,共6页
Backgroud:To explore the effects of Jianpi Bushen Recipe on the epithelial-mesenchymal transition(EMT)of nude mice with transplanted human liver cancer SK-HEP-1 cells.Methods:To establish models with transplanted live... Backgroud:To explore the effects of Jianpi Bushen Recipe on the epithelial-mesenchymal transition(EMT)of nude mice with transplanted human liver cancer SK-HEP-1 cells.Methods:To establish models with transplanted liver cancer cells,nude mice were divided randomly into three groups:blank group,traditional Chinese medicine(TCM)group and control group.They were given normal saline,Jianpi Bushen Recipe and solafeni through administration by gavage for four weeks.The expression of TGF-β and twist mRNA were detected by real-time PCR.The expression of E-cadherin was detected by Western blot.Results:Compared with the blank group,the expression of transforming growth factor-P(TGF-β)mRNA and twist mRNA in the TCM group and the control group decreased significantly(P<0.05).There was no significant difference between the two groups(P>0.05).The expression of E-cadherin protein in TCM group and control group increased significantly(P<0.01).There was no significant difference between the two groups(P>0.05).Conclusion:Jianpi Bushen Recipe can inhibit the EMT of liver cancer SK-HEP-1 cells in vivo by down-regulating the expression of TGF-β/twist signaling and indirectly up-regulating E-cadherin expression in transplanted liver cancer tissue,indicating the potential of Jianpi Bushen Recipe to inhibit invasion and metastasis of liver cancer. 展开更多
关键词 Jianpi Bushen Recipe Liver cancer Epithelial-mesenchymal transition TGF-Β TWIST E-CADHERIN
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Examination of Polymeric Azomethine Compounds and Their Transition Metal Complexes by Using XRF and XRD Technique 预览
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作者 Omer Sogut Betül Demirezen Kara +2 位作者 Gokhan Apaydin Erhan Cengiz Ayse Kazanc 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2020年第1期328-332,共5页
In this study,the electronic transition properties and structural analysis of the metal complexes(Ni(Ⅱ),Co(Ⅱ),Cu(Ⅱ)and Mn(Ⅱ))of three different polymer ligands were performed by using XRF and X-ray diffraction(XRD... In this study,the electronic transition properties and structural analysis of the metal complexes(Ni(Ⅱ),Co(Ⅱ),Cu(Ⅱ)and Mn(Ⅱ))of three different polymer ligands were performed by using XRF and X-ray diffraction(XRD)techniques,respectively.The structural analysis of the polymers and their complexes were performed by XRD technique and some of the polymers were found to be in the face-centred cubic(fcc)structure.In addition,the values of the present K X-ray intensity ratios are significantly greater than the values reported in literature. 展开更多
关键词 XRF XRD Polymeric azomethine compounds and transition metal complexes
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Observation of ^1S0→^3P0 Transition of a ^40Ca^+-^27Al^+Quantum Logic Clock
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作者 晁思嘉 崔凯枫 +3 位作者 汪绍茂 曹健 舒华林 黄学人 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第12期13-16,共4页
We report the realization of quantum logic spectroscopy on the ^1S0→^3P0 clock transition of a single ^27Al^+ion.This ion is trapped together with a ^40Ca^+ion in a linear Paul trap,coupled by Coulomb repulsion,which... We report the realization of quantum logic spectroscopy on the ^1S0→^3P0 clock transition of a single ^27Al^+ion.This ion is trapped together with a ^40Ca^+ion in a linear Paul trap,coupled by Coulomb repulsion,which provides sympathetic Doppler laser cooling and also the means for internal state detection of the clock state of the ^27Al^+ion.A repetitive quantum nondemolition measurement is performed to improve the fidelity of state detection.These techniques are applied to obtain clock spectroscopy at approximately 45 Hz.We also perform the preliminary locking on the ^1S0→^3P0 clock transition.Our work is a fundamental step that is necessary toward obtaining an ultra-precision quantum logic clock based on ^40Ca^+-^27Al^+ions. 展开更多
关键词 TRANSITION QUANTUM TRANSITION
Optimization in Transition between Two Dynamic Systems Governed by a Class of Weakly Singular Integro-Differential Equations 预览
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作者 Shihchung Chiang 《应用数学(英文)》 2019年第10期826-835,共10页
This study presents numerical methods for solving the minimum energies that satisfy typical optimal requirements in the transition between two dynamic systems where each system is governed by a different kind of weakl... This study presents numerical methods for solving the minimum energies that satisfy typical optimal requirements in the transition between two dynamic systems where each system is governed by a different kind of weakly singular integro-differential equation. The class of weakly singular integro-differential equations originates from mathematical models in aeroelasticity. The proposed numerical methods are based on earlier reported approximation schemes for the equations of the first kind and the second kind. The main result of this study is the development of numerical techniques for determining the stability between two dynamic systems in the minimum energy sense. 展开更多
关键词 Optimal REQUIREMENT TRANSITION WEAKLY SINGULAR Integro-Differential EQUATIONS Stability
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Transition Specific Risk Factors Affecting the Lifestyle Disease Progression from Diabetes to Hypertension in India 预览
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作者 Wahengbam Bigyananda Meitei Laishram Ladusingh 《健康(英文)》 2019年第8期1055-1071,共17页
Diabetes and hypertension are common co-morbid associates and coexist in many of the cases. The study attempts to understand the two-way transition between diabetes and hypertension and the risk factors affecting the ... Diabetes and hypertension are common co-morbid associates and coexist in many of the cases. The study attempts to understand the two-way transition between diabetes and hypertension and the risk factors affecting the transition using the multistate model. The study used data from the first and second waves of IHDS. There is a significant rise in the level of diabetes and hypertension from 2004-05 to 2011-12. Except for transition from hypertension to diabetes, the probability of transition in all other transition decreases and the mean waiting time to stay in the healthy state increases after adjusting for several covariates. Increases in the level of smoking, drinking of alcohol, consumption of tobacco, body mass index, education and household income quintile are the major transition specific risk factors affecting the transition between diabetes and hypertension. And the risk of transitioning from a healthy state to hypertension is higher among females compared to males. 展开更多
关键词 DIABETES HYPERTENSION TRANSITION Disease PROGRESSION INDIA
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Anisotropic iron-doping patterns in two-dimensional cobalt oxide nanoislands on Au(111)
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作者 Anthony Curto Zhaozong Sun +5 位作者 Jonathan Rodriguez-Fernandez Liang Zhang Ayush Parikh Ting Tan Jeppe V. Lauritsen Aleksandra Vojvodic 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第9期2364-2372,共9页
An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported ... An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported on Au(111).The focus is on the structure and distribution of Fe dopants within these nanoislands of CoO as a function of Fe to Co ratio.The DFT and STM results agree strongly and complement each other to allow for a more complete un dersta nding of the dopa nt structure trends on the nano scale.Using Fe as a marker,we first find that the stacki ng seque nee of the moire structure of the host cobalt oxide nano islands can be ide ntified un ambiguously through a combinati on of DFT and STM.Using the distinct con trast of the embedded Fe dopa nt atoms as observed with atom-resolved STM,we find correlatio ns betwee n Fe dopa nt positi on and the CoO/Au(111)moire patter n at varyi ng Fe dopa nt den sities.Formatio n of Fe-dopa nt clusters within the nano islands is investigated in detail through DFT and found to agree with the dopant patter ns observed in STM.We find that the structural effects of Fe dopants throughout the nanoislands with the basal planes and the two types of edges—the oxygen and metal edges—have different nature.Both DFT calculations and STM images show a strong preferenee for Fe dopants to be located directly on or near the oxygen edge of the nanoislands as opposed to being directly on or n ear the metal edge.Take n together,our results illustrate that Fe dopa nt incorporati on and distributi on within CoO nanoislands are highly an isotropic and gover ned by both the moire structure of the basal planes as well as nano-size effects present at the under-coordinated edges of different local geometry and chemistries. 展开更多
关键词 seanning TUNNELING microscopy(STM) density functional theory(DFT) cobalt oxide TRANSITION METAL OXIDES mixed TRANSITION METAL OXIDES
Urban Transition Dynamics in the Regional Rescaling of the Pearl River Delta Area:a Qualitative Approach 预览
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作者 Yang Fu 《宏观管理与公共政策(英文)》 2019年第1期7-17,共11页
The Pearl River Delta region has been the hub of urban vibrancy and boom ever since the country’s opening up and devolution reforms.However,the political and economic institutions of the cities in this region are so ... The Pearl River Delta region has been the hub of urban vibrancy and boom ever since the country’s opening up and devolution reforms.However,the political and economic institutions of the cities in this region are so different and complicated that they pose great challenges to the integration of the whole region.This study takes one prominent experiment of urban expansion,Hengqin in Zhuhai,as a case study to investigate how institutional innovations are forged and managed to boost urban development and transitions towards sustainable growth and regional integration.We adopt a multi-level perspective framework to analyze Hengqin’s urban transition.Government archives,master plans,various documents and interviews with government officials,planners,residents,and businesses from Zhuhai,Hong Kong,and Macau are chosen as sources of the analysis,which delineates the complex interactions from a variety of stakeholders.Despite difficulties in the early days,Hengqin is now transitioning quickly,although still confronted with inter-scalar challenges.A better understanding of the governance and economic innovations that have taken place,and the investment-driven development strategies involved,will help shed light on the urban transition of other similar city regions. 展开更多
关键词 URBAN TRANSITION MULTI-LEVEL Perspective Governance TRANSITION NICHE management URBAN RESCALING
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由击到养:太极拳功能价值变迁探缘
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作者 杨玉山 《中华武术(研究)》 2019年第5期20-21,45共3页
该文以太极拳功能价值变迁为研究对象,运用文献资料、逻辑分析等方法,期望探究太极拳功能价值发生变迁的原因。研究发现,太极拳功能价值变迁是始于技击,盛于养生的发展路径。这两方面是相辅相成的。
关键词 太极拳 功能价值 变迁 探缘
Boundary-layer transition of advanced fighter wings at high-speed cruise conditions
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作者 Yiming DU Zhenghong GAO +1 位作者 Chao WANG Qianhuan HUANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期799-814,共16页
The achievement of laminar flow in the boundary layer at high-speed cruise conditions may further, in addition to shock-wave control, reduce the drag and extend the range of military fighter aircraft. To this end, a f... The achievement of laminar flow in the boundary layer at high-speed cruise conditions may further, in addition to shock-wave control, reduce the drag and extend the range of military fighter aircraft. To this end, a further investigation on transitional boundary-layer flow of fighter wings is needed due to different configurations from the wings used on conventional transport aircraft. In this paper, wind tunnel experiments and numerical simulations were conducted on three-dimensional transition of thin diamond-shaped wings used on advanced fighter aircraft at tran/supersonic design points. A newly proposed correlation of crossflow transition which includes the effect of surface roughness was introduced into the c-Rehttransition model. Predicted results were in good agreement with flow visualizations. Results showed that the strength of the crossflow component grew rapidly around the leading edge because of the severe flow acceleration, just as the same as wings with a large aspect ratio. However, there seemed no regular pattern of instabilitydominance variation in span-wise for a diamond configuration. The dominance of different instability mechanisms strongly depended on the local pressure distribution. Hereby, the research recommended a ‘‘roof- like ' shape of pressure distribution to suppress both crossflow and Tollmien-Schlichting(T-S) instabilities. Besides, a sharp suction peak with a serious pressure rise should be cut off to avoid stronger instabilities. Further discussions also revealed an independence of the unit Reynolds number when transition was triggered by T-S instabilities. Aerodynamic force comparisons indicated that further benefit on drag reduction could be expected by including the three-dimensional transition effect into a wing design process. 展开更多
关键词 Boundary layer TRANSITION FIGHTER AIRCRAFT design Supersonic AIRCRAFT WINGS TRANSONIC wing AERODYNAMICS Wind tunnel measurements
The viscosity at the glass transition of a liquid lubricant
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作者 Scott BAIR 《摩擦(英文版)》 CSCD 2019年第1期86-91,共6页
In the classical study of elastohydrodynamic lubrication(EHL)which does not employ real,measurable viscosity in analysis,the possibility of a glass transition has not been considered in many years.Indeed,the two rheol... In the classical study of elastohydrodynamic lubrication(EHL)which does not employ real,measurable viscosity in analysis,the possibility of a glass transition has not been considered in many years.Indeed,the two rheological assumptions of classical EHL,the Newtonian inlet and the equivalence of a traction curve to a flow curve,would not have persisted so long had the pressure dependence of the viscosity been accurately stated.With the recent appearance of viscosity obtained from viscometers in EHL analysis,the possibility of a glass transition in the contact should be reexamined,especially for the fragile traction fluids.This article employs published data for a synthetic cycloaliphatic hydrocarbon to estimate the glass transition viscosity so that,when using real viscosities in EHL simulations,the state of the liquid may be assessed.Far into the glassy state the liquid should be treated as an elastic solid with a yield stress. 展开更多
关键词 ELASTOHYDRODYNAMIC LUBRICATION glass transition high pressure VISCOSITY EHL FRICTION
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