The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rota...The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.展开更多
Stone–Wales(SW) defects are possibly formed in graphene and other two-dimensional materials, and have multiple influence on their physical and chemical properties. In this study, the transition state of SW defects in...Stone–Wales(SW) defects are possibly formed in graphene and other two-dimensional materials, and have multiple influence on their physical and chemical properties. In this study, the transition state of SW defects in graphene is determined with the fully discrete Peierls theory. Furthermore, the atomic formation process is investigated by means of ab-initio simulations. The atomic structure change and energetics of the SW transformation are revealed. It is found that the transition state is at the SW bond rotation of 34.5°and the activation energy barrier is about 12 eV. This work provides a new method to investigate SW transformations in graphene-like materials and to explore unknown SW-type defects in other 2D materials.展开更多
Theoretical studies on the rearrangement reactions of nitropyrazoles have beeninvestigated. In order to gain a better understanding of the intermediate process of rearrangementreactions, the transition states of the r...Theoretical studies on the rearrangement reactions of nitropyrazoles have beeninvestigated. In order to gain a better understanding of the intermediate process of rearrangementreactions, the transition states of the rearrangement reactions were obtained by TS method at theB3LYP/6-311G(d, p) level of theory. The natural bond orbital charge, electrostatic potential andfrontier molecular orbital of the molecules in the process of rearrangement were analyzed, and thesolvent effect was also discussed. The rearrangement of nitropyrazoles involves two transitionstates and one intermediate, and the nitro group and hydrogen atom are two transfer groups forrearrangement reactions. The migration of these two groups leads to the change of chargedistribution and molecular structure. The structural changes of the molecules in different solventsare not significant, but the dipole moment of the molecule has obvious change.展开更多
The presence of a solvent interacting with a system brings about qualitative changes from the corresponding gas-phase reactions. A solvent can not only change the energetics along the reaction pathway, but also radica...The presence of a solvent interacting with a system brings about qualitative changes from the corresponding gas-phase reactions. A solvent can not only change the energetics along the reaction pathway, but also radically alter the reaction mechanism. Here, we investigated the water-induced transition state of the OH^-+CO2→HCO3^- reaction using a multi-level quantum mechanics and molecular mechanics method with an explicit water model. The solvent energy contribution along the reaction pathway has a maximum value which induces the highest energy point on the potential of mean force. The charge transfer from OH^- to CO2 results in the breaking of the OH^- solvation shell and the forming of the CO2 solvation shell. The loss of hydrogen bonds in the OH^- solvation shell without being compensated by the formation of hydrogen bonds in the CO2 solvation shell induces the transition state in the aqueous solution. The calculated free energy reaction barrier at the CCSD(T)/MM level of theory, 11.8 kcal/mol, agrees very well with the experimental value, 12.1 kcal/mol.展开更多
The study on transition states is one of the most important pathways to understand the essence of chemical reactions. With the development of femtoseeond pulse technique, Zewail et al. have carried out a number of exp...The study on transition states is one of the most important pathways to understand the essence of chemical reactions. With the development of femtoseeond pulse technique, Zewail et al. have carried out a number of experimental studies on the transition states, while the theoretical chemists has a great interest in the topic. In the previous展开更多
Elexible variety has all along been a hallmark of America’s global strategy withdifferentiated treatment for specific nations. In the new century, Washingtondivides the major world forces into four categories in ligh...Elexible variety has all along been a hallmark of America’s global strategy withdifferentiated treatment for specific nations. In the new century, Washingtondivides the major world forces into four categories in light of a comprehensive crite-rion of whether they have been fused into the international system, are going to-ward democracy or benefit world stability. They include: insiders or allies (Europeand Japan), marginalized ones (some underdeveloped African nations), outsidersor "rogues" (Iraq, North Korea) and finally, travelers on the way or "transitionstates". Interpretations by U.S. strategic reports define the "transition states"展开更多
In this paper, numerical simulation of shock-induced chemical reactions of intermetallic mixtures is discussed. Specifically, the paper focuses on intermetallic mixture of nickel and aluminum. To initiate the chemical...In this paper, numerical simulation of shock-induced chemical reactions of intermetallic mixtures is discussed. Specifically, the paper focuses on intermetallic mixture of nickel and aluminum. To initiate the chemical reactions, the thermal input or the shockwave should supply the energy to take the reactants, mixture of nickel and aluminum, to the transition state. Thus, for any numerical simulation or analysis of the shock or thermally induced chemical reaction in a continuum scale or a meso scale, it is necessary to identify the transition state. The transition state for the intermetallic mixture of nickel and the aluminum is identified in this paper and a result of the numerical simulation of the shock-induced chemical reaction, in a continuum scale is presented. The numerical solutions clearly show the chemical reactions, release of heat energy, increase of the temperature and the formation of products, following the transition state and the resulting shock-induced chemical reaction of a binary intermetallic energetic mixture of nickel and aluminum. The studies also show that the collapse of porosity is a mechanism that takes the reactants to the transition state, in shock-induced chemical reactions of binary intermetallic mixtures.展开更多
TiO_(2) cluster sensitivity to acetone adsorption using transition state theory is investigated.Ti_(10)O_(20) cluster is used to perform the calculations using density functional theory with dispersion corrections.Ads...TiO_(2) cluster sensitivity to acetone adsorption using transition state theory is investigated.Ti_(10)O_(20) cluster is used to perform the calculations using density functional theory with dispersion corrections.Adsorption state and transition state are calculated via thermodynamic energies,i.e.,Gibbs free energy of adsorption and activation.Reaction rate,response,response time,and recovery time as a function of temperature and acetone concentration are calculated.Acetone burning in the air due to autoignition is considered using a logistic function.The results of the theory are compared with available experimental findings that revealed the quality of both theoretical and experimental results.The response time decreases with respect to acetone concentration.On the other hand,the recovery time in the desorption phase increases with acetone concentration.The temperature of maximum response is 356℃,while the maximum response value is 2.9.展开更多
The two possible reaction paths of producing ethane on coupling reaction of methane through plasma were theoretically investigated by B3LYP and MP2 methods with 6-311G* respectively and further compared with the previ...The two possible reaction paths of producing ethane on coupling reaction of methane through plasma were theoretically investigated by B3LYP and MP2 methods with 6-311G* respectively and further compared with the previous results calculated from B3LYP/6-31G*. The new investigated results consistently confirmed the previous conclusion. And the influences of the calculation methods and basis sets on the calculated results were also dis-cussed.展开更多
1 Results Sub-and super-critical water is an attractive reaction medium for organic transformation because of their unique properties such as low viscosity,high density,low polarity,high solubility to organic compound...1 Results Sub-and super-critical water is an attractive reaction medium for organic transformation because of their unique properties such as low viscosity,high density,low polarity,high solubility to organic compounds,and,of course,the greenness of the medium[1-3]. We report herein some unique reactions of unsaturated compounds in sub-and super-critical water.When allylbenzene was treated in supercritical water (SCW: 380 ℃,10 min,water density=0.35 g/mL),double bond migrated to give a mixture of allylb...展开更多
In this paper. the abstraction reaction of CH_3SiH_3 with H has been studied by using the 'direct dynamics' method of variational transition-state theory. which is based on the information on geometries. frequ...In this paper. the abstraction reaction of CH_3SiH_3 with H has been studied by using the 'direct dynamics' method of variational transition-state theory. which is based on the information on geometries. frequencies and energies calculalcd by ab inito along the minimum energy path. The rate constants of the title reaction were calculated for the range of temperature 298-1700 K. The rate constants calculated match well with the experimental values.展开更多
In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension (KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using ...In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension (KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a reduced-gravity shallow water ocean model and the CNOP (Conditional Nonlinear Optimal Perturbation) approach. This kind of initial perturbation is called an optimal precursor (OPR). The spatial structures and evolutionary processes of the OPRs are analyzed in detail. The results show that most of the OPRs are in the form of negative sea surface height (SSH) anomalies mainly located in a narrow band region south of the KE jet, in basic agreement with altimetric observations. These negative SSH anomalies reduce the merid- ional SSH gradient within the KE, thus weakening the strength of the jet. The KE jet then becomes more convoluted, with a high-frequency and large-amplitude variability corresponding to a high eddy kinetic energy level; this gradually strengthens the KE jet through an inverse energy cascade. Eventually, the KE reaches a high-energy state characterized by two well defined and fairly stable anticyclonic meanders. Moreover, sensitivity experiments indicate that the spatial structures of the OPRs are not sensitive to the model parameters and to the optimization times used in the analysis.展开更多
Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. ...Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.展开更多
The structural features and three-dimensional nature of the charge density wave (CDW) state of the layered chalcogenide 1T-TaSe2-xTex (0≤x≤2.0) are characterized by Cs-corrected transmission electron microscopy ...The structural features and three-dimensional nature of the charge density wave (CDW) state of the layered chalcogenide 1T-TaSe2-xTex (0≤x≤2.0) are characterized by Cs-corrected transmission electron microscopy measurements. Notable changes of both average structure and the CDW state arising from Te substitution for Se are clearly demonstrated in samples with x〉0.3. The commensurate CDW state characterized by the known star-of-David clustering in the 1T-TaSe2 crystal becomes visibly unstable with Te substitution and vanishes when x=0.3. The 1T-TaSe2-xTex (0.3≤x≤1.3) samples generally adopt a remarkable incommensurate CDW state with monoclinic distortion, which could be fundamentally in correlation with the strong qq-dependent electron-phonon coupling-induced period-lattice-distortion as identified in TaTe22. Systematic analysis demonstrates that the occurrence of superconductivity is related to the suppression of the commensurate CDW phase and the presence of discommensuration is an evident structural feature observed in the superconducting samples.展开更多
State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II (PSII) and photosystem I (PSI). This pr...State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II (PSII) and photosystem I (PSI). This process depends on the reversible phosphorylation/dephosphorylation of the major light-harvesting complex II (LHCII) and its bi-directional migration between PSII and PSI. But it remains unclear how phosphorylation/dephosphorylation modulates the LHCII conformation and further regulates its reversible migration. Here molecular dynamics simulations (MDS) were employed to elucidate the impact of phosphorylation on LHCII conformation. The results indicated that N-terminal phosphorylation loosened LHCII trimer with decreased hydrogen bond (H-bond) interactions and extended the distances between neighboring monomers, which stemmed from the conformational ad- justment of each monomer itself. Global conformational change of LHCII monomer started from its stromal N- terminal (including the phosphorylation sites) by enhancing its interaction to lipid membrane and by adjusting the interaction network with surrounded inter-monomer andintra-monomer transmembrane helixes of B, C, and A, and finally triggered the reorientation of transmembrane helixes and transferred the conformational change to luminal side helixes and loops. These results further our understanding in molecular mechanism of LHCII migration during state transition from the phosphorylation-induced microstructural feature of LHCII.展开更多
The influences of silica volume fraction, electrolyte concentration and pH value upon the stress dependence of elastic modulus G′and viscous modulus G″ were investigated. The results show that the suspension transfo...The influences of silica volume fraction, electrolyte concentration and pH value upon the stress dependence of elastic modulus G′and viscous modulus G″ were investigated. The results show that the suspension transforms from a liquid-like state to a solid-like state with increasing the volume fraction of silica. Such a solid-like state can be transformed back into a liquid-like state under the application of a larger stress. At the higher volume fraction, the larger critical stress is required to induce the transition from solid-like to liquid-like state. As the electrolyte concentration decreases or pH value increases, the inter-particle force increases, which causes the state transition to occur at a higher stress.展开更多
Textured silicon (Si) substrates decorated with regular microscale square pillar arrays of nearly the same side length, height, but different intervals are fabricated by inductively coupled plasma, and then silanize...Textured silicon (Si) substrates decorated with regular microscale square pillar arrays of nearly the same side length, height, but different intervals are fabricated by inductively coupled plasma, and then silanized by self-assembly octadecyl- trichlorosilane (OTS) film. The systematic water contact angle (CA) measurements and micro/nanoscale hierarchical rough structure models are used to analyze the wetting behaviors of original and silanized textured Si substrates each as a function of pillar interval-to-width ratio. On the original textured Si substrate with hydrophilic pillars, the water droplet possesses a larger apparent CAs (〉 90~) and contact angle hysteresis (CAH), induced by the hierarchical roughness of microscale pil- lar arrays and nanoscale pit-like roughness. However, the silanized textured substrate shows superhydrophobicity induced by the low free energy OTS overcoat and the hierarchical roughness of microscale pillar arrays, and nanoscale island-like roughness. The largest apparent CA on the superhydrophobic surface is 169.8~. In addition, the wetting transition of a gently deposited water droplet is observed on the original textured substrate with pillar interval-to-width ratio increasing. Furthermore, the wetting state transition is analyzed by thermodynamic approach with the consideration of the CAH effect. The results indicate that the wetting state changed from a Cassie state to a pseudo-Wenzel during the transition.展开更多
The Bayesian approach is considered as the most general formulation of the state estimation for dynamic systems. However, most of the existing Bayesian estimators of stochastic hybrid systems only focus on the Markov ...The Bayesian approach is considered as the most general formulation of the state estimation for dynamic systems. However, most of the existing Bayesian estimators of stochastic hybrid systems only focus on the Markov jump system, few liter- ature is related to the estimation problem of nonlinear stochastic hybrid systems with state dependent transitions. According to this problem, a new methodology which relaxes quite a restrictive as- sumption that the mode transition process must satisfy Markov properties is proposed. In this method, a general approach is presented to model the state dependent transitions, the state and output spaces are discreted into cell space which handles the nonlinearities and computationally intensive problem offline. Then maximum a posterior estimation is obtained by using the Bayesian theory. The efficacy of the estimator is illustrated by a simulated example .展开更多
The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s...The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s2s, and 1s2p states of He I, are investigated using the multi-configuration Dirac–Hartree–Fock method. In the subsequent relativistic configuration interaction computations, the Breit interaction and the QED effect are considered as perturbation, separately. Our transition energies, oscillator strengths, and transition rates are in good agreement with the experimental and other theoretical results. As a result, the QED effect is not important for helium atoms, however, the effect of the Breit interaction plays a significant role in the transition energies, the oscillator strengths and transition rates.展开更多
INTRODUCTION The conformational state transition of polymer chains relates to crystallization processes, migration ofthe chains in solution, fluctuation of the end-to-end distance of random coils, and the relaxation a...INTRODUCTION The conformational state transition of polymer chains relates to crystallization processes, migration ofthe chains in solution, fluctuation of the end-to-end distance of random coils, and the relaxation and phasetransitions of polymers. A description of the conformational state transition requires questions about; 1) howmany stable conformational states for a specific σ bond; 2) the barriers between the states; 3) the mechanismof the conformational transition; 4) any cooperative behavior during the transition. Flory and his coworkers展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11074078)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)+1 种基金the Key Program for Scientific and Technological Innovations of Higher Education Institutes in Guangdong Province,China(Grant No.cxzd1011)the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant No.C10183)
文摘The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11847089)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant No. 20KJB430002)GuiZhou Provincial Department of Science and Technology, China (Grant No. QKHJC[2019]1167)。
文摘Stone–Wales(SW) defects are possibly formed in graphene and other two-dimensional materials, and have multiple influence on their physical and chemical properties. In this study, the transition state of SW defects in graphene is determined with the fully discrete Peierls theory. Furthermore, the atomic formation process is investigated by means of ab-initio simulations. The atomic structure change and energetics of the SW transformation are revealed. It is found that the transition state is at the SW bond rotation of 34.5°and the activation energy barrier is about 12 eV. This work provides a new method to investigate SW transformations in graphene-like materials and to explore unknown SW-type defects in other 2D materials.
文摘Theoretical studies on the rearrangement reactions of nitropyrazoles have beeninvestigated. In order to gain a better understanding of the intermediate process of rearrangementreactions, the transition states of the rearrangement reactions were obtained by TS method at theB3LYP/6-311G(d, p) level of theory. The natural bond orbital charge, electrostatic potential andfrontier molecular orbital of the molecules in the process of rearrangement were analyzed, and thesolvent effect was also discussed. The rearrangement of nitropyrazoles involves two transitionstates and one intermediate, and the nitro group and hydrogen atom are two transfer groups forrearrangement reactions. The migration of these two groups leads to the change of chargedistribution and molecular structure. The structural changes of the molecules in different solventsare not significant, but the dipole moment of the molecule has obvious change.
基金supported by the National Natural Science Foundation of China(Grant No.11374194)Taishan Scholarship Fund from Shandong Province,China
文摘The presence of a solvent interacting with a system brings about qualitative changes from the corresponding gas-phase reactions. A solvent can not only change the energetics along the reaction pathway, but also radically alter the reaction mechanism. Here, we investigated the water-induced transition state of the OH^-+CO2→HCO3^- reaction using a multi-level quantum mechanics and molecular mechanics method with an explicit water model. The solvent energy contribution along the reaction pathway has a maximum value which induces the highest energy point on the potential of mean force. The charge transfer from OH^- to CO2 results in the breaking of the OH^- solvation shell and the forming of the CO2 solvation shell. The loss of hydrogen bonds in the OH^- solvation shell without being compensated by the formation of hydrogen bonds in the CO2 solvation shell induces the transition state in the aqueous solution. The calculated free energy reaction barrier at the CCSD(T)/MM level of theory, 11.8 kcal/mol, agrees very well with the experimental value, 12.1 kcal/mol.
基金Supported by the National Natural Science Foundation of China
文摘The study on transition states is one of the most important pathways to understand the essence of chemical reactions. With the development of femtoseeond pulse technique, Zewail et al. have carried out a number of experimental studies on the transition states, while the theoretical chemists has a great interest in the topic. In the previous
文摘Elexible variety has all along been a hallmark of America’s global strategy withdifferentiated treatment for specific nations. In the new century, Washingtondivides the major world forces into four categories in light of a comprehensive crite-rion of whether they have been fused into the international system, are going to-ward democracy or benefit world stability. They include: insiders or allies (Europeand Japan), marginalized ones (some underdeveloped African nations), outsidersor "rogues" (Iraq, North Korea) and finally, travelers on the way or "transitionstates". Interpretations by U.S. strategic reports define the "transition states"
文摘In this paper, numerical simulation of shock-induced chemical reactions of intermetallic mixtures is discussed. Specifically, the paper focuses on intermetallic mixture of nickel and aluminum. To initiate the chemical reactions, the thermal input or the shockwave should supply the energy to take the reactants, mixture of nickel and aluminum, to the transition state. Thus, for any numerical simulation or analysis of the shock or thermally induced chemical reaction in a continuum scale or a meso scale, it is necessary to identify the transition state. The transition state for the intermetallic mixture of nickel and the aluminum is identified in this paper and a result of the numerical simulation of the shock-induced chemical reaction, in a continuum scale is presented. The numerical solutions clearly show the chemical reactions, release of heat energy, increase of the temperature and the formation of products, following the transition state and the resulting shock-induced chemical reaction of a binary intermetallic energetic mixture of nickel and aluminum. The studies also show that the collapse of porosity is a mechanism that takes the reactants to the transition state, in shock-induced chemical reactions of binary intermetallic mixtures.
文摘TiO_(2) cluster sensitivity to acetone adsorption using transition state theory is investigated.Ti_(10)O_(20) cluster is used to perform the calculations using density functional theory with dispersion corrections.Adsorption state and transition state are calculated via thermodynamic energies,i.e.,Gibbs free energy of adsorption and activation.Reaction rate,response,response time,and recovery time as a function of temperature and acetone concentration are calculated.Acetone burning in the air due to autoignition is considered using a logistic function.The results of the theory are compared with available experimental findings that revealed the quality of both theoretical and experimental results.The response time decreases with respect to acetone concentration.On the other hand,the recovery time in the desorption phase increases with acetone concentration.The temperature of maximum response is 356℃,while the maximum response value is 2.9.
基金Project supported by the Natural Science Foundation of Tianjin Education Commission (No. 20020902) and the Youth Fund Project of Tianjin Nor-mal University (No. 52LE31).
文摘The two possible reaction paths of producing ethane on coupling reaction of methane through plasma were theoretically investigated by B3LYP and MP2 methods with 6-311G* respectively and further compared with the previous results calculated from B3LYP/6-31G*. The new investigated results consistently confirmed the previous conclusion. And the influences of the calculation methods and basis sets on the calculated results were also dis-cussed.
文摘1 Results Sub-and super-critical water is an attractive reaction medium for organic transformation because of their unique properties such as low viscosity,high density,low polarity,high solubility to organic compounds,and,of course,the greenness of the medium[1-3]. We report herein some unique reactions of unsaturated compounds in sub-and super-critical water.When allylbenzene was treated in supercritical water (SCW: 380 ℃,10 min,water density=0.35 g/mL),double bond migrated to give a mixture of allylb...
文摘In this paper. the abstraction reaction of CH_3SiH_3 with H has been studied by using the 'direct dynamics' method of variational transition-state theory. which is based on the information on geometries. frequencies and energies calculalcd by ab inito along the minimum energy path. The rate constants of the title reaction were calculated for the range of temperature 298-1700 K. The rate constants calculated match well with the experimental values.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41576015, 41306023, 41490644 and 41490640)the Natural Science Foundation Of China (NSFC) Innovative Group (Grant No. 41421005)+1 种基金the NSFC–Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)support from the University of Naples Parthenope (Grant No. DSTE315)
文摘In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension (KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a reduced-gravity shallow water ocean model and the CNOP (Conditional Nonlinear Optimal Perturbation) approach. This kind of initial perturbation is called an optimal precursor (OPR). The spatial structures and evolutionary processes of the OPRs are analyzed in detail. The results show that most of the OPRs are in the form of negative sea surface height (SSH) anomalies mainly located in a narrow band region south of the KE jet, in basic agreement with altimetric observations. These negative SSH anomalies reduce the merid- ional SSH gradient within the KE, thus weakening the strength of the jet. The KE jet then becomes more convoluted, with a high-frequency and large-amplitude variability corresponding to a high eddy kinetic energy level; this gradually strengthens the KE jet through an inverse energy cascade. Eventually, the KE reaches a high-energy state characterized by two well defined and fairly stable anticyclonic meanders. Moreover, sensitivity experiments indicate that the spatial structures of the OPRs are not sensitive to the model parameters and to the optimization times used in the analysis.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047 and 61071025)
文摘Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.
基金Supported by the National Basic Research Program of China under Grant Nos 2015CB921300 and 2012CB821404the National Key Research and Development Program of China under Grant Nos 2016YFA0300300 and 2016YFA0300404+1 种基金the National Natural Science Foundation of China under Grant Nos 11474323,11604372,11274368,91221102,11190022,11674326 and 91422303the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant No XDB07020000
文摘The structural features and three-dimensional nature of the charge density wave (CDW) state of the layered chalcogenide 1T-TaSe2-xTex (0≤x≤2.0) are characterized by Cs-corrected transmission electron microscopy measurements. Notable changes of both average structure and the CDW state arising from Te substitution for Se are clearly demonstrated in samples with x〉0.3. The commensurate CDW state characterized by the known star-of-David clustering in the 1T-TaSe2 crystal becomes visibly unstable with Te substitution and vanishes when x=0.3. The 1T-TaSe2-xTex (0.3≤x≤1.3) samples generally adopt a remarkable incommensurate CDW state with monoclinic distortion, which could be fundamentally in correlation with the strong qq-dependent electron-phonon coupling-induced period-lattice-distortion as identified in TaTe22. Systematic analysis demonstrates that the occurrence of superconductivity is related to the suppression of the commensurate CDW phase and the presence of discommensuration is an evident structural feature observed in the superconducting samples.
基金supported by the National Key Basic Research Foundation of China(2006CB910303 and 2011CB710904)the National Natural Science Foundation of China(11072251 and31230027)+1 种基金the CAS Knowledge Innovation Program(KJCX2YW-L08)the Scientific Research Equipment Project(Y2010030)
文摘State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II (PSII) and photosystem I (PSI). This process depends on the reversible phosphorylation/dephosphorylation of the major light-harvesting complex II (LHCII) and its bi-directional migration between PSII and PSI. But it remains unclear how phosphorylation/dephosphorylation modulates the LHCII conformation and further regulates its reversible migration. Here molecular dynamics simulations (MDS) were employed to elucidate the impact of phosphorylation on LHCII conformation. The results indicated that N-terminal phosphorylation loosened LHCII trimer with decreased hydrogen bond (H-bond) interactions and extended the distances between neighboring monomers, which stemmed from the conformational ad- justment of each monomer itself. Global conformational change of LHCII monomer started from its stromal N- terminal (including the phosphorylation sites) by enhancing its interaction to lipid membrane and by adjusting the interaction network with surrounded inter-monomer andintra-monomer transmembrane helixes of B, C, and A, and finally triggered the reorientation of transmembrane helixes and transferred the conformational change to luminal side helixes and loops. These results further our understanding in molecular mechanism of LHCII migration during state transition from the phosphorylation-induced microstructural feature of LHCII.
基金the National Natural Science Foundation of China(No.2 0 2 4 30 0 2 )
文摘The influences of silica volume fraction, electrolyte concentration and pH value upon the stress dependence of elastic modulus G′and viscous modulus G″ were investigated. The results show that the suspension transforms from a liquid-like state to a solid-like state with increasing the volume fraction of silica. Such a solid-like state can be transformed back into a liquid-like state under the application of a larger stress. At the higher volume fraction, the larger critical stress is required to induce the transition from solid-like to liquid-like state. As the electrolyte concentration decreases or pH value increases, the inter-particle force increases, which causes the state transition to occur at a higher stress.
基金Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No.NCET-09-0211)the Fundamental Research Funds for the Central Universities (Grant Nos.2012YJS105 and M13JB00240)
文摘Textured silicon (Si) substrates decorated with regular microscale square pillar arrays of nearly the same side length, height, but different intervals are fabricated by inductively coupled plasma, and then silanized by self-assembly octadecyl- trichlorosilane (OTS) film. The systematic water contact angle (CA) measurements and micro/nanoscale hierarchical rough structure models are used to analyze the wetting behaviors of original and silanized textured Si substrates each as a function of pillar interval-to-width ratio. On the original textured Si substrate with hydrophilic pillars, the water droplet possesses a larger apparent CAs (〉 90~) and contact angle hysteresis (CAH), induced by the hierarchical roughness of microscale pil- lar arrays and nanoscale pit-like roughness. However, the silanized textured substrate shows superhydrophobicity induced by the low free energy OTS overcoat and the hierarchical roughness of microscale pillar arrays, and nanoscale island-like roughness. The largest apparent CA on the superhydrophobic surface is 169.8~. In addition, the wetting transition of a gently deposited water droplet is observed on the original textured substrate with pillar interval-to-width ratio increasing. Furthermore, the wetting state transition is analyzed by thermodynamic approach with the consideration of the CAH effect. The results indicate that the wetting state changed from a Cassie state to a pseudo-Wenzel during the transition.
基金supported by the National Natural Science Foundation of China (6097400161104121)the Fundamental Research Funds for the Central Universities (JUDCF11039)
文摘The Bayesian approach is considered as the most general formulation of the state estimation for dynamic systems. However, most of the existing Bayesian estimators of stochastic hybrid systems only focus on the Markov jump system, few liter- ature is related to the estimation problem of nonlinear stochastic hybrid systems with state dependent transitions. According to this problem, a new methodology which relaxes quite a restrictive as- sumption that the mode transition process must satisfy Markov properties is proposed. In this method, a general approach is presented to model the state dependent transitions, the state and output spaces are discreted into cell space which handles the nonlinearities and computationally intensive problem offline. Then maximum a posterior estimation is obtained by using the Bayesian theory. The efficacy of the estimator is illustrated by a simulated example .
基金Supported by the National Key Research and Development Program of China (Grant No. 2017YFA0402300)the National Natural Science Foundation of China (Grant Nos. 11774344 and 11474033)。
文摘The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s2s, and 1s2p states of He I, are investigated using the multi-configuration Dirac–Hartree–Fock method. In the subsequent relativistic configuration interaction computations, the Breit interaction and the QED effect are considered as perturbation, separately. Our transition energies, oscillator strengths, and transition rates are in good agreement with the experimental and other theoretical results. As a result, the QED effect is not important for helium atoms, however, the effect of the Breit interaction plays a significant role in the transition energies, the oscillator strengths and transition rates.
文摘INTRODUCTION The conformational state transition of polymer chains relates to crystallization processes, migration ofthe chains in solution, fluctuation of the end-to-end distance of random coils, and the relaxation and phasetransitions of polymers. A description of the conformational state transition requires questions about; 1) howmany stable conformational states for a specific σ bond; 2) the barriers between the states; 3) the mechanismof the conformational transition; 4) any cooperative behavior during the transition. Flory and his coworkers