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equilibria between the K^+ binding and cation vacancy conformations of potassium channels

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Protein & Cell 2019年第7期10卷 533-537页

作者： Yao He Bo Zhang Hao Dong Penglin Xu Xiaoying Cai Ting Zhou Mu Yu Jun Liang Xiao Zheng Changlin Tian Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences University of Science and Technology of China Hefei 230027 China Kuang Yaming Honors School and Institute for Brain Sciences Nanjing University Nanjing 210023 China Hefei National Laboratory for Physical Sciences at the Microscale and School of Chemistry and Material Sciences University of Science and Technology of China Hefei 230026 China

Dear Editor, Potassium channels are integral membrane proteins that selectively con duct K^+ ions across cell membra ne (Hille, 2001). They play essential roles in maintaining cellular ionic homoeostasis and generating action membrane potentials in excitable cells. The mechanism of K^+ selectivity has been evaluated in many biophysical and physiological studies (Zhou et al., 2001;Liu et al., 2015;Schewe et al., 2016). A highly con served signature seque nee, TVGYG, in the selectivity filter of potassium channels (e.g., KcsA) is known to coordinate K^+ ions (Zhou et al., 2001). Carbonyls of these residues point toward the pore, forming four continuous ion binding sites (S1-S4) and resulting in higher selectivity for K^+ over Na^+(Zhou et al., 2001). The NaK channel from Bacillus cereus is a norvselective cation channel that shares high structural homology with KcsA (Shi et al., 2006). Owing to a distinctive primary sequenee of 63TVGDG67, the selectivity filter of NaK preserves only two ion binding sites, allocated similarly as S3 and S4 in KcsA (Alam and Jiang, 2009a, b). Remarkably, the D66Y and N68D double mutations of NaK channel (Fig. S1) transform it into a K^+ selective channel (termed as NaK2K)(Sauer et al., 2013). Crystal structure of NaK and NaK2K have revealed distinet binding coordination of Na^+ and K^+ ions in their selectivity filter (Figs. S2 and S3)(Alam and Jiang, 2009a, b;Sauer et al., 2013). However, dynamics of the NaK and NaK2K selectivity filter with the bind泊g of Na+ or K^+ are still elusive. Especially, it has been known that the membrane environment is highly diverse from deterge nt micelles, which was con sidered to in flue nee the structure and functi on of membrane protei ns dramatically (Cross et al., 2011). Thus, it is necessary to study the cation and binding properties of NaK NaK2K channels in lipid bilayers.

关键词： equilibria K^+binding cation vacancy conformations

Free-boundary plasma equilibria with toroidal plasma flows

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Plasma Science and Technology 2022年第3期24卷 61-70页

作者：陈文锦马志为张豪伟张威严龙文 Institute for Fusion Theory and Simulation.Zhejiang University Hangzhou 310027People's Republic of China Southwestern Institute of Physics Chengdu 610225People's Republic of China

Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the'divertor-type'and'limiter-type'free boundaries in the tokamak cylindrical coordinate.With a toroidal plasma flow,the flux functions are considerably different under the isentropic and isothermal assumptions.The effects of the toroidal flow on the magnetic axis shift are investigated.In a high beta plasma,the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a_(0)(a_(0)is the minor radius)for M_(0)=0.2(the toroidal Alfvén Mach number on the magnetic axis).In addition,the X-point is slightly shifted upward by 0.0125a_(0).But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M_(0) is usually less than 0.05 in a real tokamak.The effects of the toroidal flow on the plasma parameters are also investigated.The high toroidal flow shifts the plasma outward due to the centrifugal effect.Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case.

关键词： tokamak plasma plasma flow equilibria

A G^E/Equation of State Mixing Rule for Vapor-Liquid equilibria

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Chinese Journal of Chemical Engineering 1998年第3期6卷 14-28页

作者：屈一新汪文川 Lee Y.Y. Chung K.Y. Lee Y.W. Korea Institute of Science and Technology SeoulKorea

A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and Sandler.The mixing rulewas extensively tested in terms of a comprehensive data base,consisting of 52 simple nonpolar-nonpolar,carbon dioxide containing,hydrocarbon-hydrocarbon,CFC,polar-polar,nonpolar-polarbinary and multicomponent systems.Focused on the complete predictive capability,a comparisonbetween the Wong-Sandler and the mixing rule proposed was conducted.The results indicate that thenew mixing rule is in general superior to the Wong-Sandler’s,and the binary interaction parameteras required by the latter is removed,which reduces computing effort and is reliable in predictions ofvapor-liquid equilibria from low pressures to high pressures.

关键词： vapor-liquid equilibria equation of state mixing rule

Coalitional equilibria in Coalitional Abstract Economies with Nonordered Preferences

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Journal of Systems Science & Complexity 2020年第1期33卷 137-145页

作者： YANG Zhe GONG Qingbin School of Economics Shanghai University of Finance and EconomicsShanghai 200433China Key Laboratory of Mathematical Economics(SUFE) Ministry of EducationShanghai 200433China

This paper investigates the existence of coalitional equilibria for coalitional abstract economies with nonordered preferences.Accordingly,the authors give a fuzzy extension of the coalitional equilibrium existence theorem.The main result is illustrated with applications to coalitional abstract economies with payoff functions,strong Nash equilibria and absolute optimal solutions.

关键词： Absolute optimal solution coalitional abstract economy coalitional equilibria equilibrium existence strong Nash equilibria

The Performance of EOS Models in the Prediction of Vapor-Liquid equilibria in Asymmetric Natural Gas Mixtures

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Chinese Journal of Chemical Engineering 1998年第3期6卷 29-37页

作者：王利生 H.Gardeler J.Gmehling Department of Technical Chemisity University of OldenburgP.O.Box 2503D-26111 OldenburgGermany

The aim of this work is to apply cubic equations of state(EOS)to vapor-liquid equilibriacalculations of gas-heavy hydrocarbon systems,which are asymmetric in molecular size and areusually found in natural gases.Investigation has been done to test the validity of the original PSRKand the cubic simplified perturbed hard-chain(CSPhC)models for global phase diagrams.Thecalculation results show that both equations overpredict vapor pressure in the near critical region.In the prediction of the solubilities of high molecular weight(MW)hydrocarbons in the naturalgas,the PSRK model gives good agreement for the dew point pressure-vapor composition diagrams.Adjustment of the pure component parameters of the CSPHC EOS for heavy components to fit thevapor-liquid equilibrium(VLE)data has been proved to give significant promoting in predictionaccuracy.However,further improvement of a van der Waals EOS,such as SRK,PT and DG modelsfor the asymmetric systems by adjusting the three pure component properties,T_c, p_c and ?

关键词： equation of state natural gas vapor-liquid equilibria asymmetric systems

ROBUSTNESS OF equilibria IN THE GRAPH MODEL FOR CONFLICT RESOLUTION

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Journal of Systems Science and Systems Engineering 2015年第4期24卷 450-465页

作者： Yasser T.Matbouli D.Marc Kilgour Keith W.Hipel Department of Industrial Engineering King Abdulaziz University Department of Systems Design Engineering University of Waterloo Department of Mathematics Wilfrid Laurier University Centre for International Governance Innovation(CIGI)

A novel approach for assessing the robustness of an equilibrium in conflict resolution is presented. Roughly, an equilibrium is robust if it is resilient, or resistant to deviation. Robustness assessment is based on a new concept called Level of Freedom, which evaluates the relative freedom of a decision maker to escape an equilibrium. Resolutions of a conflict can be affected by changes in decision makers＇ preferences, which may destabilize an equilibrium, causing the conflict to evolve. Hence, a conflict may become long-term and thereby continue to evolve, even after reaching an equilibrium. The new robustness measure is used to rank equilibria based on robustness, to facilitate distinguishing equiiibria that are relatively sustainable. An absolutely robust equilibrium is a special case in which the level of freedom is at an absolute minimum for each individual stability definition.

关键词： Robustness equilibria level of freedom conflict evolution graph model

Phase equilibria of supercritical CO_2-ethanol-stearic acid ternary system and hydrogen bonding between ethanol and stearic acid

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Science China Chemistry 1998年第4期41卷 410-417页

作者：关冰鲁洁韩布兴闫海科 Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

Solubility of stearic acid in supercritical CO 2 with ethanol cosolvent was determined at 308.15 K in the pressure range from 8 to 16 MPa, and the cosolvent concentration ranges from 0 mol% to 4 mol%. The corresponding densities of the fluid phases were also measured. It was observed that ethanol enhances the solubility significantly. The solubility increases with pressure noticeably at lower pressure, especially at lower cosolvent concentrations. The effect of pressure on the solubility is very limited at higher pressures or higher cosolvent concentrations. The hydrogen bonding between ethanol and stearic acid in supercritical CO 2 was also studied using FTIR in order to understand the mechanism of the solubility enhancement by ethanol.

关键词： phase equilibria supercritical CO 2 stearic acid ethanol hydrogen bonding.

STABILITY OF equilibria OF NEMATIC LIQUID CRYSTALLINE POLYMERS

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Acta Mathematica Scientia 2011年第6期31卷 2289-2304页

作者： Hong Zhou Hongyun Wang Department of Applied MathematicsNaval Postgraduate School Monterey CA 93943 USA Department of Applied Mathematics and StatisticsUniversity of California Santa Cruz CA 95064 USA

We provide an analytical study on the stability of equilibria of rigid rodlike nematic liquid crystalline polymers （LCPs） governed by the Smoluchowski equation with the Maier-Saupe intermolecular potential. We simplify the expression of the free energy of an orientational distribution function of rodlike LCP molecules by properly selecting a coordinate system and then investigate its stability with respect to perturbations of orientational probability density. By computing the Hessian matrix explicitly, we are able to prove the hysteresis phenomenon of nematic LCPs： when the normalized polymer concentration b is below a critical value b＊（6.T314863965）, the only equilibrium state is isotropic and it is stable; when b＊〈 b 〈 15/2, two anisotropic （prolate） equilibrium states occur together with a stable isotropic equilibrium state. Here the more aligned prolate state is stable whereas the less aligned prolate state is unstable. When b 〉 15/2, there are three equilibrium states： a stable prolate state, an unstable isotropie state and an unstable oblate state.

关键词： equilibria stability nematic liquid crystalline polymers hysteresis phenomenon

Solid and liquid phase equilibria and solid-hydrate formation in binary mixtures of water with amines

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Science China Chemistry 1997年第5期40卷 491-494页

作者：车冠全彭文烈黄良恩古喜兰车飙 Department of Chemistry Zhongshan UniversityGuangzhou 510275China

Solid and liquid phase diagrams have been constructed for {water+triethylamine,or+N,N-dimethylformamide(DMF) or+N,N-dimethlacetamide (DMA)} Solid-hydrates form with the empirical formulae N(C2H5)3 3H2O,DMF 3H2O,DMF 2H2O,DMA 3H2O and (DMA)2 3H2O.All are congruently melting except the first which melts incongruently.The solid-hydrate formation is attributed to hydrogen bond.The results are compared with the

关键词： phase diagram solid and liquid equilibria hydrate amide triethylamine