Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural ...Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was investigated.The physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium ions.Simulations indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the material.The dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at 5C.Additionally,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at 1C.These results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.展开更多
In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dy...In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long span suspension bridges during erection.展开更多
This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments...This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments and GDAZ （geodynamic active zones） are presented on the map. Geodynamic active zones are linear or isometric crust volumes of different scales that localized spatially, where conditions for tectonic stress concentration and relaxation, and high gradients of movements and rocks deformity are favorable by different reasons. They differ from active faults, which are rare on geodynamic-stable platform territories, by absence of noticeable displacements in rocks and a more geodynamic stability. Nevertheless, GDAZ can be hazard to engineering buildings, since these zones are favorable for developing exogenous （such as erosion, impoundment, karst, sliding, etc.） and endogenous geological processes （such as seismicity, water-fluid permeability and heat flux）. They can also become migration and localization channels of nature-anthropogenic pollution.展开更多
Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows ...Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows that some proteins have even lower free energy in inter- mediate states and their native states are kinetically trapped in the higher free energy region. This article explores the stability condition of protein structures on the basis of our study of complex chemical systems. We believe that sep- arating one from another is not reasonable since they should be coupled, and protein structures should be dom- inated by at least two mechanisms resulting in different characteristic states. It is concluded that： （1） Structures of proteins are dynamic, showing multiple characteristic states emerging alternately and each dominated by a respective mechanism. （2） Compromise in competition of multiple dominant mechanisms might be the key to understanding the stability of protein structures. （3） The dynamic process of protein folding should be depicted through the time series of both its energetic and structural changes, which is much meaningful and applicable than the free energy landscape.展开更多
We propose and study a predator prey model with state-dependent delay where the prey population is assumed to have an age structure. The state-dependent delay appears due to the mature condition that the prey must spe...We propose and study a predator prey model with state-dependent delay where the prey population is assumed to have an age structure. The state-dependent delay appears due to the mature condition that the prey must spend an amount of time in the immature stage sufficient to accumulate a threshold amount of food. We perform a qualitative analysis of the solutions, which includes studying positivity and boundedness, existence and local stability of equilibria. For the global dynamics of the system, we discuss an attracting region which is determined by solutions, and the region collapses to the interior equilibrium in the constant delay case.展开更多
This paper studies the dynamics of the analytic family z + 1/z + b alld describes the topologyof the parameter space, structural stability and J-stability. The mapping class group of almostall maps of the above family...This paper studies the dynamics of the analytic family z + 1/z + b alld describes the topologyof the parameter space, structural stability and J-stability. The mapping class group of almostall maps of the above family is determined.展开更多
We formulate an age-structured model based on a system of nonlinear partial differen- tial equations to assist the early and catch up female vaccination programs for human papillomavirus （HPV） types 6 and 11. Since ...We formulate an age-structured model based on a system of nonlinear partial differen- tial equations to assist the early and catch up female vaccination programs for human papillomavirus （HPV） types 6 and 11. Since these HPV types do not induce permanent immunity, the model, which stratifies the population based on age and gender, has a susceptible-infectious-susceptible （SIS） structure. We calculate the effective reproduction number Rv for the model and describe the local-asymptotic stability of the disease-free equilibrium using Rv. We prove the existence of an endemic equilibrium for Rv 〉 1 for the no vaccine case. However, analysis of the model for the vaccine case reveals that it undergoes the phenomenon of backward bifurcation. To support our theoretical results, we estimate the age and time solution with the given data for Toronto population, when an early and catch up female vaccine program is adopted, and when there is no vaccine. We show that early and catch up female vaccine program eliminates the infection in both male and female populations over a period of 30 years. Finally, we introduce the optimal control to an age-dependent model based on ordinary differential equations and solve it numerically to obtain the most cost-effective method for introducing the catch up vaccine into the population.展开更多
Using the particle swarm optimization algorithm on crystal structure prediction,we first predict that Mg Y alloy undergoes a first-order phase transition from Cs Cl phase to P4/NMM phase at about 55 GPa with a small v...Using the particle swarm optimization algorithm on crystal structure prediction,we first predict that Mg Y alloy undergoes a first-order phase transition from Cs Cl phase to P4/NMM phase at about 55 GPa with a small volume collapse of 2.63%.The dynamical stability of P4/NMM phase at 55 GPa is evaluated by the phonon spectrum calculation and the electronic structure is discussed.The elastic constants are calculated,after which the bulk moduli,shear moduli,Young's modui,and Debye temperature are derived.The brittleness/ductile behavior,and anisotropy of two phases under pressure are discussed in details.Our results show that external pressure can change the brittle behavior to ductile at10 GPa for Cs Cl phase and improve the ductility of Mg Y alloy.As pressure increases,the elastic anisotropy in shear of Cs Cl phase decreases,while that of P4/NMM phase remains nearly constant.The elastic anisotropic constructions of the directional dependences of reciprocals of bulk modulus and Young's modulus are also calculated and discussed.展开更多
基金financial support from the National Natural Science Foundation of China(No.52377220)the Natural Science Foundation of Hunan Province,China(No.kq2208265)。
文摘Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was investigated.The physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium ions.Simulations indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the material.The dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at 5C.Additionally,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at 1C.These results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.
文摘In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long span suspension bridges during erection.
文摘This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments and GDAZ （geodynamic active zones） are presented on the map. Geodynamic active zones are linear or isometric crust volumes of different scales that localized spatially, where conditions for tectonic stress concentration and relaxation, and high gradients of movements and rocks deformity are favorable by different reasons. They differ from active faults, which are rare on geodynamic-stable platform territories, by absence of noticeable displacements in rocks and a more geodynamic stability. Nevertheless, GDAZ can be hazard to engineering buildings, since these zones are favorable for developing exogenous （such as erosion, impoundment, karst, sliding, etc.） and endogenous geological processes （such as seismicity, water-fluid permeability and heat flux）. They can also become migration and localization channels of nature-anthropogenic pollution.
基金supported by the National Natural Science Foundation of China(21103195)the Knowledge Innovation Program of Chinese Academy of Sciences(KGCX2-YW-124)
文摘Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows that some proteins have even lower free energy in inter- mediate states and their native states are kinetically trapped in the higher free energy region. This article explores the stability condition of protein structures on the basis of our study of complex chemical systems. We believe that sep- arating one from another is not reasonable since they should be coupled, and protein structures should be dom- inated by at least two mechanisms resulting in different characteristic states. It is concluded that： （1） Structures of proteins are dynamic, showing multiple characteristic states emerging alternately and each dominated by a respective mechanism. （2） Compromise in competition of multiple dominant mechanisms might be the key to understanding the stability of protein structures. （3） The dynamic process of protein folding should be depicted through the time series of both its energetic and structural changes, which is much meaningful and applicable than the free energy landscape.
文摘We propose and study a predator prey model with state-dependent delay where the prey population is assumed to have an age structure. The state-dependent delay appears due to the mature condition that the prey must spend an amount of time in the immature stage sufficient to accumulate a threshold amount of food. We perform a qualitative analysis of the solutions, which includes studying positivity and boundedness, existence and local stability of equilibria. For the global dynamics of the system, we discuss an attracting region which is determined by solutions, and the region collapses to the interior equilibrium in the constant delay case.
文摘This paper studies the dynamics of the analytic family z + 1/z + b alld describes the topologyof the parameter space, structural stability and J-stability. The mapping class group of almostall maps of the above family is determined.
文摘We formulate an age-structured model based on a system of nonlinear partial differen- tial equations to assist the early and catch up female vaccination programs for human papillomavirus （HPV） types 6 and 11. Since these HPV types do not induce permanent immunity, the model, which stratifies the population based on age and gender, has a susceptible-infectious-susceptible （SIS） structure. We calculate the effective reproduction number Rv for the model and describe the local-asymptotic stability of the disease-free equilibrium using Rv. We prove the existence of an endemic equilibrium for Rv 〉 1 for the no vaccine case. However, analysis of the model for the vaccine case reveals that it undergoes the phenomenon of backward bifurcation. To support our theoretical results, we estimate the age and time solution with the given data for Toronto population, when an early and catch up female vaccine program is adopted, and when there is no vaccine. We show that early and catch up female vaccine program eliminates the infection in both male and female populations over a period of 30 years. Finally, we introduce the optimal control to an age-dependent model based on ordinary differential equations and solve it numerically to obtain the most cost-effective method for introducing the catch up vaccine into the population.
基金Supported by the Henan Joint Funds of the National Natural Science Foundation of China under Grant Nos.U1304612,U1404608the National Natural Science Foundation of China under Grant Nos.51501093,51374132+2 种基金the Special Fund of the Theoretical Physics of China under Grant No.11247222Postdoctoral Science Foundation of China under Grant No.2015M581767Young Core Instructor Foundation of Henan Province under Grant No.2015GGJS-122
文摘Using the particle swarm optimization algorithm on crystal structure prediction,we first predict that Mg Y alloy undergoes a first-order phase transition from Cs Cl phase to P4/NMM phase at about 55 GPa with a small volume collapse of 2.63%.The dynamical stability of P4/NMM phase at 55 GPa is evaluated by the phonon spectrum calculation and the electronic structure is discussed.The elastic constants are calculated,after which the bulk moduli,shear moduli,Young's modui,and Debye temperature are derived.The brittleness/ductile behavior,and anisotropy of two phases under pressure are discussed in details.Our results show that external pressure can change the brittle behavior to ductile at10 GPa for Cs Cl phase and improve the ductility of Mg Y alloy.As pressure increases,the elastic anisotropy in shear of Cs Cl phase decreases,while that of P4/NMM phase remains nearly constant.The elastic anisotropic constructions of the directional dependences of reciprocals of bulk modulus and Young's modulus are also calculated and discussed.
