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To model the molten globule structure of -lactalbumin, moleculardynamics (MD) simulations were carried out for the protein inexplicit water at high temperature. In these simulations, long-rangeCoulomb interactions were evaluated explicitly with an originalmethod (particleparticle and particlecell: PPPC)to avoid artifacts caused by the cut-off. The MD simulationswere started from two initial conditions to verify that similarresults would be obtained. From the last 150 ps trajectoriesof the two MD simulations, two partially unfolded average structureswere obtained. These structures had the following common structuralfeatures which are characteristic of the molten globule state.The radii of gyration for these conformations were 7.4 and 9.6%larger than that of the native state. These values were almostthe same as the experimental value (9.6%) observed recentlyby small-angle X-ray scattering (Kataoka,M., Kuwajima,K., Tokunaga,F.and Goto,Y., 1997, Protein Sci., 6, 422430). Furthermore,aromatic residues of clusters I and II in these structures werefar apart from each other except for Try103Trp104. Thisresult is in good agreement with NMR experimental results forthe acid-denatured molten globule state (Alexandrescu et al.,1992, 1993); that is, NOE signals between the aromatic residueswere not observed, except for that of Try103Trp104 inthe molten globule state. Other structural features of thesemodels for the molten globule state are discussed with referenceto native state structures. 相似文献
57.
《Calphad》2014
Experimental investigations and Gibbs energy modelling of KCl–LiCl–UCl3 system employing CALPHAD method are reported. Gibbs energy modelling of the subsystems KCl–UCl3 and LiCl–UCl3 was carried out primarily using phase diagram data from the literature. For the Gibbs energy modelling of the KCl–LiCl subsystem, new phase boundary data corresponding to four terminal compositions , 0.05, 0.95 and 0.97) obtained through differential thermal analysis data along with thermochemical and phase diagram data from the literature were used. Thermal analysis was also carried out for KCl–LiCl eutectic mixture containing small amounts of UCl3 and ). The liquidus temperatures for these compositions were found to be 637 K and 674 K. Electromotive force data for dilute solutions of UCl3 in the KCl–LiCl eutectic melt, measured in the temperature range 708–833 K in the present work, were found to be in good agreement with the literature data. These data were also used as input for the Gibbs energy modelling of the KCl–LiCl–UCl3 system. In order to improve the quality of the resulting Gibbs energy functions of the quasibinaries and the quasiternary, enthalpies of mixing of the corresponding melts estimated using an empirical correlation based on surrounded-ion model were also used as input. Finally, the generated Gibbs energy functions were used to compute phase equilibria. 相似文献
58.
Y. Castrillejo M. R. Bermejo A. M. Martínez C. Abejón S. Sánchez G. S. Picard 《Journal of Applied Electrochemistry》1999,29(1):65-73
The stability of indium chloride and oxide as well as the electrochemical behaviour of indium ions have been studied in the equimolar CaCl2–NaCl melt at 550 C by X-ray diffraction (XRD) and different electrochemical techniques, using molybdenum and tungsten wires as working electrodes. Voltammetric and chronopotentiometric studies showed signals attributed to the presence of three oxidation states of indium, i.e. 0, i and iii. The standard potential of the redox couples, as well as the solubility products of indium oxides have been determined, showing that In(iii) ions are completely reduced to monovalent indium by the indium metal according to the reaction: In () + 2 In 3 In () and that In2O is a strong oxide donor according to the reaction: In2O(s) 2 In() + O2- These results have allowed the construction of E-pO2– equilibrium diagrams summarising the properties of In–O compounds. The electrodeposition of indium was uncomplicated at Mo and W electrodes. Very good adherence of liquid indium to the electrode materials was observed, with the formation of Na–In alloys at highly reducing potentials, and there was no evidence of indium dissolution into the melt. Moreover, the voltammograms corresponding to the electrochemical In(iii)/In(i) exchange were well defined. The two electrochemical steps were found to be quasi-reversible, and the values of the kinetic parameters, ko and , for both reactions, as well as the diffusion coefficients, DIn(III) and DIn(I) were calculated. 相似文献
59.
采用电导法研究了水溶液中盐的浓度与其电导率的关系,根据模拟水样和实际水样在电导率与全盐量的关系上有较好的吻合性,介绍了电导法测定水中全盐量的方法,结果表明在低浓度范围内电导率与盐浓度成线性关系,与传统的重量法相比,具有快速、简便、准确度高的特点。 相似文献
60.
超重力反应结晶法纳米碳酸钙浆料及粉料的表面处理 总被引:3,自引:0,他引:3
研究了脂肪酸盐A、水溶性铁酸酯偶联剂B(B1)以及铁酸酯偶联剂C对新型超重力反应结晶法所得的纳米CaCO3浆料及粉料的湿法表面处理的配方与工艺,确定了A体系的最佳改性时间为30~40min、改性温度为40~50℃、改性剂用量(质量分数)为3%~5%;B(B1)体系搅拌强度必须很高,改性时间30~40min,改性温度80℃左右,改性剂用量(质量分数)3%~5%;C体系的最佳改性时间为30~40min,改性剂用量(质量分数)为3%~5%。同时,采用红外光谱对改性前后的纳米碳酸钙进行了表征,表明改性刑已连接至CaCO3表面。最后,用分散稳定模型简要分析了改性机理。 相似文献