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structural stability in discrete singular systems

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Chinese Physics B 2002年第12期11卷 1221-1227页

作者：吴健荣杨成梧 DepartmentofAppliedMathematics UniversityofScienceandTechnologyofSuzhouSuzhou215011China SchoolofPowerEingineering NanjingUniversityofScienceandTechnologyNanjing210094China Sc

In this paper, we study the structural stability of singular discrete systems with perturbations in coefficient matrices. Some sufficient and necessary conditions of structurally stable singular discrete systems are g... 详细信息

关键词： singular discrete system structural stability normal compensator

Effects of Fe solid solute on grain boundaries of bi-crystal Cu: A molecular dynamics simulation

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Nano Materials Science 2024年第1期6卷 86-95页

作者： Shuohan Yang Hongwei Bao Huizhong Bai Yan Li Haodong Xu Fei Ma State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049ShaanxiChina

Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.

关键词： CuFe alloy Grain boundary structural stability MD simulations

Exact Geometric Relationships, Symmetry Breaking and structural stability for Single-Walled Carbon Nanotubes

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Nano-Micro Letters 2011年第4期3卷 228-235页

作者： Tong Zhang Ze Shuai Yuan Li Hao Tan Research Center for Solid Mechanics Beihang University

We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.

关键词： Geometry structural stability Symmetry Breaking Fractal Dimension

The existence form and synergistic effect of P in improving the structural stability and electrochemical performance of Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode materials

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Journal of Materiomics 2018年第3期4卷 179-186页

作者： Lei Wei Shi-Xi Zhao Xia Wu Shu-Jin Zhao Ce-Wen Nan Graduate School at Shenzhen Tsinghua UniversityShenzhen518055China School of Materials Science and Engineering Tsinghua UniversityBeijing100084China School of Materials Science and Engineering Jiamusi UniversityJiamusi154007China

Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution content,P element completely enters into the lattice,forms[PO_(4)]tetrahedrons and partially replaces[SiO_(4)]tetrahedrons,which is confirmed by X-ray diffraction and X-ray photoelectron spectroscope measurements.Phosphorus substitution helps to suppress the change of coordination number of Mn and stabilize the material structure to some extent,obtaining better electrochemical performance in the early cycle.With the increase of P content,parts of P element exist in Li_(3)PO_(4)which distributes uniformly and co-exists with active substance.Electrochemical tests prove that existing Li_(3)PO_(4)has positive impacts on cycle and rate performance,and the lithium ion diffusion coefficient increases by about 14 times than pristine sample.Under the synergistic effects of phosphate substation and proper Li_(3)PO_(4),Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C shows enhanced electrochemical performances.

关键词： Lithium-ion batteries Cathode material Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C P-doping Synergistic effect structural stability

Enhanced structural stability of adenovirus nanocapsule

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Progress in Natural Science:Materials International 2014年第2期24卷 171-174页

作者： Ding Weng Ziyue Karen Jiang Jing Jin Lily Wu Yunfeng Lu Chemical and Biomolecular Engineering University of California at Los Angeles Tissue Engineering Laboratories VA Boston Healthcare System Department of Orthopaedic Surgery Brigham and Women's Hospital Harvard Medical School Molecular and Medical Pharmacology University of California at Los Angeles Getein Biotechnology Co. Ltd.

Application of viral vector in gene therapy and vaccination is still limited by their structural stability, which significantly increased avoidable cost in storage and transportation. Herein a non-covalent conjugated low-pH degradable nanocapsule has been adopted to stabilize viral vectors. By utilizing a luciferase expressing adenovirus, AdCMVLuc, we succeeded in a raise of over 11 folds in AdCMVLuc’s structural stability after 12 days storage at 4 1℃.

关键词： Non-covalent nanocapsule Adenovirus structural stability

Assessment of structural stability in Bohai Sea area based on AHP-GDM model

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Acta Oceanologica Sinica 2013年第4期32卷 41-48页

作者： XIU Zongxiang LIU Baohua XIE Qiuhong LI Xishuang LIU Chenguang PEI Yanliang ZHENG Yanpeng The First Institute of Oceanography State Oceanic Administration Key Laboratory of Marine Sedimentology and Environmental Geology National Deep Sea Center

The AHP-GDM model is used for the assessment of structural stability, with the Bohai Sea area as an exam- ple. In this model, the credit degree of each expert is calculated through the assessment matrix based on the similarity and diversity of vector. The comprehensive opinions of expert panel are quantitatively obtained by considering the effect ofcredit degree. According to the geological structural setting, the Bohai Sea is di- vided into twelve assessment zones of structural stability by non-uniform element method. The structural stability grade of each zone is obtained on the basis of the latest geophysical data, earthquake statistical data, and the information of fault activities, current stress field and crustal deformation. The results show that there are one relatively stable area, three relatively sub-stable areas, six relatively sub-unstable areas and two relatively unstable areas. The assessment results of non-uniform element method are very close with those of uniform grid method with size of 0.25 in longitude direction and 0.14 in latitude direction. However the workload of non-uniform element method is only 1 / 16 of the latter. Compared with traditional assessment methods of structural stability, a more objective and reliable assessment result can be obtained by combining non-uniform element method and AHP-GDM model.

关键词： AHP-GDM Mode Bohai Sea structural stability non-uniform element method

Study of high pressure structural stability of CeO_2 nanoparticles

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Chinese Physics C 2013年第9期37卷 94-98页

作者：刘波刘然李全军姚明光邹勃崔田刘冰冰刘景 State Key Laboratory of Superhard Materials Jilin University Institute of High Energy Physics Chinese Academy of Sciences

In situ high pressure XRD diffraction and Raman spectroscopy have been performed on 12 nm CeO2 nanoparticles. Surprisingly, under quasihydrostatic conditions, 12 nm CeO2 nanoparticles maintain the fluorite- type structure in the whole pressure range （0-51 GPa） during the experiments, much more stable than the bulk counterpart （PT-31 GPa）. In contrast, they experienced phase transition at pressure as low as 26 GPa under non- hydrostatic conditions （adopting CsC1 as pressure medium）. Additionally, 32-36 nm CeO2 nanoparticles exhibit an onset pressure of phase transition at 35 GPa under quasihydrostatic conditions, and this onset pressure is much lower than our result. Further analysis shows both the experimental condition （i.e., quasihydrostatic or non-hydrostatic） and grain size effect have a significant impact on the high pressure behaviors of CeO2 nanomaterials.

关键词： Ce02 nanomaterials high pressure experimental conditions grain size effect structural stability

Mechanistic Insights into structural stability of the Selectivity Filters in Typical Cation Channels

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Journal of Materials Science and Chemical Engineering 2022年第7期10卷 17-32页

作者： Zhoubin Tang Hu Qiu Wanlin Guo Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education State Key Laboratory of Mechanics and Control of Mechanical Structure College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing China

The reliable functioning of ion channels should be closely related to their structural stability. The selectivity filter in the KcsA potassium channel possesses four stable ion binding sites that can coordinate nearly fully dehydrated ions, whereas only two of such binding sites exist in the non-selective NaK channel, and none of them is found in the NavAb sodium channel. Here we show that the stability of the selectivity filters in these tetrameric cation channels is inversely correlated with the number of stable binding sites by extensive molecular dynamics simulations. While the presence of coordinated ions is crucial for the selectivity filters of the KcsA and NaK channels to stabilize the conformations in their crystal structures, the selectivity filter of the NavAb channel shows higher stability, independent of the presence of ions. We further show that the distinct repulsive electrostatic interactions between negatively charged oxygen atoms in the selectivity filter which form the stable binding sites are responsible for the different stability of these cation channels. The hydrogen bonding networks between residues in the selectivity filter and its adjacent pore helix also play an important role in maintaining stability. Together, these results provide important mechanistic insights into the structural stability of the selectivity filters in typical cation channels.

关键词： Ion Channel structural stability Molecular Dynamics Electrostatic Potential Hydrogen Bonds

First-Principle Investigation of the structural stability and Electronic Property of Precipitates on the Cu-Rich Side of Cu-Ni-Si Alloys

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Journal of Shanghai Jiaotong university(Science) 2011年第3期16卷 266-271页

作者：龙永强刘平刘勇贾淑果田宝红 School of Materials Science and Engineering Shanghai Jiaotong University School of Materials Science and Engineering Henan University of Science and Technology College of Mechanical Engineering University of Shanghai for Science and Technology School of Materials Science and Engineering Henan University of Science and Technology

The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.

关键词： precipitate first-principles electronic structure structural stability Cu-Ni-Si alloy