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1.
We present all-atom molecular dynamics simulations ofn-hexane on the basal plane of graphite at monolayer and multilayer coverages. In keeping with experimental data, we find the
presence of ordered adsorbed layers both at single monolayer coverage and when the adsorbed layer coexists with excess liquid
adsorbate. Using a simulation method that does not impose any particular periodicity on the adsorbed layer, we quantitatively
compare our results to the results of neutron diffraction experiments and find a structural transition from a uniaxially incommensurate
lattice to a fully commensurate structure on increasing the coverage from a monolayer to a multilayer. The zig-zag backbone
planes of all the alkane molecules lie parallel to the graphite surface at the multilayer coverage, while a few molecules
are observed to attain the perpendicular orientation at monolayer coverage.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
2.
Yong‐Jin Kim Jin‐Woong Kim Jung‐Eun Lee Jee‐Hyun Ryu Junoh Kim Ih‐Seop Chang Kyung‐Do Suh 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5627-5635
Mesoporous polymer microspheres with gold (Au) nanoparticles inside their pores were prepared considering their surface functionality and porosity. The Au/polymer composite microspheres prepared were characterized by transmission electron microscope (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) techniques. The results showed that the adsorption of Au nanoparticles could be increased by imparting the pore structure and surface‐functional groups into the supporting polymer microspheres (in this study, poly (ethylene glycol dimethacrylate‐co‐acrylonitrile) and poly (EGDMA‐co‐AN) system). Above all, from this study, it was established that the porosity of the polymer microspheres is the most important factor that determines the distribution and adsorption amount of face‐centered cubic (fcc) Au nanoparticles in the final products. Our study showed that the continuous adsorption of Au nanoparticles with the aid of the large surface area and surface interaction sites formed more favorably the Au/polymer composite microspheres. The BET measurements of Au/poly(EGDMA‐co‐AN) composite microspheres reveals that the adsorption of Au nanoparticles into the pores kept the pore structure intact and made it more porous. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5627–5635, 2004 相似文献
3.
本文报道了用吸附溶出伏安法测定毗喳酮.以悬汞电极为工作电极,在Na}B,O,-NaOH介质(pH=10)中,毗喳酮产生一尖锐的吸附还原峰,E,二一1. 29V (vs. SCE ),峰电流与毗喳酮浓度在2. 0 X 10-'-8. 0 X 10-smol " L-’范围内呈良好的线性关系.检测限为2. 0 X 10-0mol " L-'(富集90s).本文对毗喳酮在悬汞电极上的电化学行为进行了探讨,对测定毗喳酮的最佳条件进行了详细的选择,利用本法测定了片剂中毗喳酮含量,结果满意. 相似文献
4.
This article describes the technique of fast atom bombardment mass spectrometry (FAB MS) and its applications to the analysis of organometallic and coordination complexes. Sections on ion generation and matrices are followed by a Periodic Group-based review of FAB MS results obtained from Transition Metal and Main Group compounds, organometallic cluster carbonyls and their derivatives, and salts of poly-oxo-anions. The literature has been surveyed from 1981 to approximately mid-1986. 相似文献
5.
The parameters that affect the shape of the band profiles of acido‐basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pKa are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 μL) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C18‐bonded packing materials, including the 5 μm Xterra‐C18 (121 Å), 5 μm Gemini‐C18 (110 Å), 5 μm Luna‐C18(2) (93 Å), 3.5 μm Extend‐C18 (80 Å), and 2.7 μm Halo‐C18 (90 Å). The mobile phase was an aqueous solution of methanol buffered at a constant WWpH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3‐phenyl 1‐propanol, 2‐phenyl butyric acid, amphetamine, aniline, benzylamine, p‐toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pKa and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution. 相似文献
6.
The viscosities of aqueous solutions of gelatin at different temperatures were carefully measured in a common glass‐capillary Ubbelohde viscometer at dilute to extremely dilute concentrations. The adsorption effect that occurred in the viscosity measurements was theoretically analyzed and discussed. A theory based on Langmuir isotherms could adequately describe the existing data. Some structural information was obtained by the use of an iterative fitting procedure to treat the reduced viscosity data, which disclosed that individual gelatin chains underwent a coil‐to‐helix transition as the solution cooled from 40 to 15 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1804–1812, 2006 相似文献
7.
根据CTP在离子交换树脂上的吸附容量和分离因数的大小,确定Duolite A-30树脂适合CTP与CDP,CMP之间的分离.对CTP在Duolite A-30树脂上的吸附动力学和热力学研究表明,在283.15K~303.15K之间,CTP的质量浓度在7.5g/L以上时,Duolite A-30树脂对CTP的吸附主要受颗粒扩散的控制,其有效扩散系数为D=3.47×10-7cm2/s,溶液的质量浓度≤1.0g/L时,CTP与Duolite A-30树脂之间的交换速率主要受液膜控制,其液膜扩散系数为Kf =4.112×10-4/s.同时测定了不同条件下三磷酸胞苷溶液在Duolite A-30树脂固定床离子交换柱中的穿透曲线,研究了进口浓度、进口流速、原料液温度、原料液的pH值及柱高对穿透曲线的影响.用二阶动力学推动力模型描述固定床动态过程,考察了轴向返混对穿透曲线的影响,并从穿透曲线回归得到总传质系数,模型计算值与实验数据符合良好. 相似文献
8.
Gary W. Schnuelle S. Swaminathan David L. Beveridge 《Theoretical chemistry accounts》1978,48(1):17-27
A theoretical study of ion hydration using the statistical thermodynamic supermolecule-continuum method is described. The cell and shell methods are used for configurational averaging. Enthalpies, free energies and entropies are calculated for Li+, Na+, K+, F– and Cl– each four coordinated with water. The results are in reasonable accord with experiment. A comparison of the site method, cell method and shell method results is presented. The supermolecule-continuum approach to solvent effects seems to be capable of accommodating essential features for the calculation of solvation energy and solvent effects on structure and properties. 相似文献
9.
10.