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131.
杂合型全局优化法优化水分子团簇结构 总被引:2,自引:0,他引:2
基于遗传算法、快速模拟退火及共轭梯度方法提出了一种快速的杂合型全局优化方法(fast hybrid global optimization algorithm, FHGOA),并将这一方法应用于TIP3P和TIPS2模型水分子团簇(H2O)n结构的优化.在进行TIP3P模型水分子团簇结构的优化过程中,发现了能量比文献值更低的团簇结构,且执行效率有较大提高.把该方法应用到优化TIPS2模型的水分子团簇,发现最优结构和采用TTM2-F模型优化的水分子团簇结构在n < 17时完全相同,为全表面结构;而在n=17、19、22时为单中心水分子笼状结构;在n=25、27时为双中心水分子笼状结构.说明随着团簇中水分子个数的增加,采用TIPS2和TTM2-F势能函数优化的团簇最优结构有相同的变化趋势. 相似文献
132.
The controlled synthesis of SrCO3 nanostructures with different morphologies, such as rodlike, whiskerlike, ellipsoidlike, and spherelike, were successfully achieved by the cationic surfactant-CTAB-microemulsion-mediated solvothermal method. Various comparison experiments showed that fundamental experimental parameters, such as the molar ratio of H2O to CTAB and the concentration of reactants, played important roles in the morphological control of SrCO3 nanostructures. A lower molar ratio of H2O to CTAB favors rodlike products, whereas a higher molar ratio generally leads to the formation of spherical products. A rational mechanism based on fusion, aggregate, and coalescence of microemulsion droplets is proposed for the selective formation of various morphologies. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and field-emission scanning electron microscope (FE-SEM) were used to characterize the products. 相似文献
133.
The explicit tau-leaping procedure attempts to speed up the stochastic simulation of a chemically reacting system by approximating the number of firings of each reaction channel during a chosen time increment tau as a Poisson random variable. Since the Poisson random variable can have arbitrarily large sample values, there is always the possibility that this procedure will cause one or more reaction channels to fire so many times during tau that the population of some reactant species will be driven negative. Two recent papers have shown how that unacceptable occurrence can be avoided by replacing the Poisson random variables with binomial random variables, whose values are naturally bounded. This paper describes a modified Poisson tau-leaping procedure that also avoids negative populations, but is easier to implement than the binomial procedure. The new Poisson procedure also introduces a second control parameter, whose value essentially dials the procedure from the original Poisson tau-leaping at one extreme to the exact stochastic simulation algorithm at the other; therefore, the modified Poisson procedure will generally be more accurate than the original Poisson procedure. 相似文献
134.
135.
Photocatalytic oxidation of water is a promising method to realize large-scale H2O2 production without a hazardous and energy-intensive process. In this study, we introduce a Pt/TiO2(anatase) photocatalyst to construct a simple and environmentally friendly system to achieve simultaneous H2 and H2O2 production. Both H2 and H2O2 are high-value chemicals, and their separation is automatic. Even without the assistance of a sacrificial agent, the system can reach an efficiency of 7410 and 5096 μmol g–1 h–1 (first 1 h) for H2 and H2O2, respectively, which is much higher than that of a commercial Pt/TiO2(anatase) system that has a similar morphology. This exceptional activity is attributed to the more favorable two-electron oxidation of water to H2O2, compared with the four-electron oxidation of water to O2. 相似文献
136.
Substituent effects on monoboronic acid sensors for saccharides based on N-phenyl-1,8-naphthalenedicarboximides 总被引:4,自引:0,他引:4
In the course of our investigations on new monoboronic acid saccharide sensors with C(0) spacers, a series of probes 1-6 based on 1,8-naphthalenedicarboximide were synthesized. Sensor 1 displays features typical of PET monoboronic acid sensors and shows high selectivity to fructose. Sensor 2 exhibits a novel dual emission and remarkable sensitivity for glucose relative to fructose and galactose through subtle changes in pH. Sensor 3 displays significantly enhanced fluorescence in the presence of galactose at low pH. Although probes 4-6 exhibit unique properties such as high quantum yield (Phi(F) = 0.407) and excellent solubility in water, they did not show significant change in fluorescence intensity in the presence of monosaccharides. The effects of substituent on all six probes lend support to the proposed photoelectrochemical model. 相似文献
137.
Bi Xian Tonghua Li Chen Kai Tongcheng Cao Jianrong Huang Yunpeng Qi 《Journal of mathematical chemistry》2004,36(2):129-138
Orthogonal signal correction (OSC) was a data preprocessing algorithm. It ensured that the filtered information was irrelevant to concentration data while using it to filter the noise from the original data. This paper extended the OSC application range from two-way data to three-way data. Two drug data sets, Enoxacin, Norfloxacin, Ciprofloxacin and Betamethasone, cortisone acetate, prednisone acetate, showed that the application of the OSC algorithm to three-way HPLC data was feasible and needed further research. 相似文献
138.
The exact residues within severe acute respiratory syndrome coronavirus (SARS-CoV) S1 protein and its receptor, human ACE2, involved in their interaction still remain largely undetermined. Identification of exact amino acid residues that are crucial for the interaction of S1 with ACE2 could provide working hypotheses for experimental studies and might be helpful for the development of antiviral inhibitor. In this paper, a molecular docking model of SARS-CoV S1 protein in complex with human ACE2 was constructed. The interacting residue pairs within this complex model and their contact types were also identified. Our model, supported by significant biochemical evidence, suggested receptor-binding residues were concentrated in two segments of S1 protein. In contrast, the interfacial residues in ACE2, though close to each other in tertiary structure, were found to be widely scattered in the primary sequence. In particular, the S1 residue ARG453 and ACE2 residue LYS341 might be the key residues in the complex formation. 相似文献
139.
JPC – Journal of Planar Chromatography – Modern TLC - In this work we have studied the separation of a mixture of the sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron,... 相似文献
140.
The title compounds 6a—6f were prepared with high yield via intramolecular Wittig reaction of methyl 3-perfluoroalkyl-6-peifluoroacyl-2-triphenylphosphoranylidenchex-3,5-dienoates (5a—5i) which were obtained from the reaction of 3-perfluoroacylprop-2-enylidenetriphenylphosphoranes (3a—3c) with methyl perfluoroalkynoates (4a—4c). 相似文献