“Transition States” Testing America's Global Strategy

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"

Shock Induced Chemical Reactions of Intermetallic Mixture of Nickel and Aluminum and Associated Transition States

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.

8-Membered-ring Transition States of Water Assisted Reactions in Sub-and Super-critical Water

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...

Charge Density Wave States and Structural Transition in Layered Chalcogenide TaSe_(2-x)Te_x

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.

Density Functional Theory and MP2 Calculations of the Transition States and Reaction Paths on Coupling Reaction of Methane through Plasma

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.

Transition Between Solid-like and Liquid-like States in Soft Silica Suspensions

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.

Effect of Electron Correlation and Breit Interaction on Energies, Oscillator Strengths, and Transition Rates for Low-Lying States of Helium

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.

A circular zone counting method of identifying a Duffing oscillator state transition and determining the critical value 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.

Multimodal process monitoring based on transition-constrained Gaussian mixture model

Reliable process monitoring is important for ensuring process safety and product quality.A production process is generally characterized bymultiple operation modes,and monitoring thesemultimodal processes is challenging.Most multimodal monitoring methods rely on the assumption that the modes are independent of each other,which may not be appropriate for practical application.This study proposes a transition-constrained Gaussian mixture model method for efficient multimodal process monitoring.This technique can reduce falsely and frequently occurring mode transitions by considering the time series information in the mode identification of historical and online data.This process enables the identified modes to reflect the stability of actual working conditions,improve mode identification accuracy,and enhance monitoring reliability in cases of mode overlap.Case studies on a numerical simulation example and simulation of the penicillin fermentation process are provided to verify the effectiveness of the proposed approach inmultimodal process monitoring with mode overlap.

Optimal Precursors Triggering the Kuroshio Extension State Transition Obtained by the Conditional Nonlinear Optimal Perturbation Approach

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.

Ab Initio Calculation of 4f→5d Transition Energy and Electronic Structure of Ce^(3+) Doped in LiYF_4 Crystal

The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.

Transition state to mode locking in a passively mode-locked erbium-doped fibre ring laser

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.

Ab initio calculation of electronic structures and 4f-5d transitions of some rare earth ions doped in crystal YPO_4

The ab initio self-consistent DV-Xa （discrete variational Xa） method was used in its relativistic and spin-polarized model to investigate the ground-state electronic structttres of the crystal YPO4 and YPO4：RE^3＋ （RE=Ce, Pr and Sm） and f-d transition energies of the lattice. The calculation was performed on the clusters Y5P10O32 and REY4P10O32 embedded in a microcrystal containing about 1500 ions, respectively. The ground-state calculation provided the locations of the 4f and 5d crystal-field one-electron levels of RE^3＋ relative to the valence and conduction bands of host, the curve of total and the partial density of states, and the corresponding occupation numbers, etc. Especially, the transition-state calculation was performed to obtain the 4f→5d transition energies of RE^3＋ in comparison to the experimental observations. The lattice relaxation caused by the dopant ion RE3＋ was discussed based on the total energy calculation and the transition-state calculation of the f-d transition energies.

Transition state and formation process of Stone–Wales defects in graphene

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.

Theoretical Study on the Transition State of N-nitropyrazoles Rearrangement Reaction

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.

Precisely quantifying bulk transition metal valence evolution in conventional battery electrode by inverse partial fluorescence yield

Precisely quantifying transition metal(TM) redox in bulk is a key to understand the fundamental of optimizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard X-ray absorption spectroscopy(hXAS) and soft X-ray absorption spectroscopy(sXAS).However, they are both facing challenges to precisely quantify the valence states of some transition metals such as Mn. In this paper, Mn-L iPFY(inverse partial fluorescence yield) spectra extracted from Mn-L m RIXS(mapping of resonant inelastic X-ray scattering) is adopted to quantify Mn valence states. Mn-L i PFY spectra has been considered as a bulk-sensitive, non-distorted probe of TM valence states.However, the exact precision of this method is still unclear in quantifying practical battery electrodes.Herein, a series of LiMn_(2)O_(4) electrodes with different charge and discharge states are prepared. Based on their electrochemical capacity(generally considered to be very precise), the precision of Mn iPFY in quantifying bulk Mn valence state is confirmed, and the error range is unraveled. Mn-L mRIXS iPFY thus is identified as one of the best methods to quantify the bulk Mn valence state comparing with hXAS and sXAS.

Ab Initio Calculation of 4f→5d Transition Energy and Electronic Structure of Ce^(3+) Doped in LiYF_(4) Crystal

The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.

Combined multi-level quantum mechanics theories and molecular mechanics study of water-induced transition state of OH^- + CO_2 reaction in aqueous solution

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.

The impact of N-terminal phosphorylation on LHCII conformation in state transition

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.

Transition State and Catastrophe Set

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