Study of structural parameters on the adsorption selectivity of a molecularly imprinted polymer

This work was focused on the influence of match degree of structure parameters i.e. molecular size, volume and polarity (denoted as R_d, V_d and P_d) between imprinted cavities in Qu-MIP and Xn on the adsorption selectivity. The results presented that the influence of R_d on the adsorption selectivity was the largest and the most regular, while the influence of P_d was the smallest and the most irregular. Besides, the influence degree of V_d was decreased in general with the increase of R_d. However, as R_d was in the threshold of [0.99, 1.02], V_d would rise to the major influence factor. Furthermore, utilizing data obtained from experiment, the influence authority of R_d, V_d and P_d on the adsorption selectivity was calculated theoretically through multiple linear regression and principal component analysis of IBM SPSS Statistics 20, and results showed the authority order was R_d, V_d and P_d at any circumstance despite the value was different, which was in accordance with the result we directly inducted from the experiment.     

Effect of water on the retention on diol and amide columns in hydrophilic interaction liquid chromatography

The amount of water adsorbed on polar columns plays important role in hydrophilic interaction liquid chromatography. It may strongly differ for the individual types of polar columns used in this separation mode. We measured adsorption isotherms of water on an amide and three diol‐bonded stationary phases that differ in the chemistry of the bonded ligands and properties of the silica gel support. We studied the effects of the adsorbed water on the retention of aromatic carboxylic acids, flavonoids, benzoic acid derivatives, nucleic bases, and nucleosides in aqueous‐acetonitrile mobile phases over the full composition range. The graphs of the retention factors versus the volume fraction of water in mobile phase show “U‐profile” characteristic of a dual hydrophilic interaction–reversed phase retention mechanism. The minimum on the graph that marks the changing retention mechanism depends on the amount of adsorbed water. The linear solvation energy relationship model suggests that the retention in the hydrophilic interaction liquid chromatography mode is controlled mainly by proton–donor interactions in the stationary phase, depending on the column type. Finally, the accuracy of hydrophilic interaction liquid chromatography gradient prediction improves for columns that show a high water adsorption.     

Preparation of magnetic molecularly imprinted polymer nanoparticles by surface imprinting by a sol–gel process for the selective and rapid removal of di‐(2‐ethylhexyl) phthalate from aqueous solution

Magnetic molecularly imprinted polymer nanoparticles for di‐(2‐ethylhexyl) phthalate were synthesized by surface imprinting technology with a sol–gel process and used for the selective and rapid adsorption and removal of di‐(2‐ethylhexyl) phthalate from aqueous solution. The prepared magnetic molecularly imprinted polymer nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and vibrating sample magnetometry. The adsorption of di‐(2‐ethylhexyl) phthalate onto the magnetic molecularly imprinted polymer was spontaneous and endothermic. The adsorption equilibrium was achieved within 1 h, the maximum adsorption capacity was 30.7 mg/g, and the adsorption process could be well described by Langmuir isotherm model and pseudo‐second‐order kinetic model. The magnetic molecularly imprinted polymer displayed a good adsorption selectivity for di‐(2‐ethylhexyl) phthalate with respect to dibutyl phthalate and di‐n‐octyl phthalate. The reusability of magnetic molecularly imprinted polymer was demonstrated for at least eight repeated cycles without significant loss in adsorption capacity. The adsorption efficiencies of the magnetic molecularly imprinted polymer toward di‐(2‐ethylhexyl) phthalate in real water samples were in the range of 98–100%. These results indicated that the prepared adsorbent could be used as an efficient and cost‐effective material for the removal of di‐(2‐ethylhexyl) phthalate from environmental water samples.     

Thin Poly(Di(Ethylene Glycol)Methyl Ether Methacrylate) Homopolymer Brushes Allow Controlled Adsorption and Desorption of PaTu 8988t Cells

Poly(di(ethylene glycol)methyl ether methacrylate) (PDEGMA) brushes, which are known to suppress protein adsorption and prevent cell attachment, are reported here to possess interesting and tunable thermoresponsive behavior, if the brush thickness is reduced or the grafting density is altered. PDEGMA brushes with a dry ellipsometric thickness of 5 ± 1 nm can be switched from cell adherent behavior at 37 °C to cell nonadherent at 25 °C. This behavior coincides with the temperature‐dependent irreversible adsorption of fibronectin from phosphate saline buffer and proteins present in the cell culture medium, as unveiled by surface plasmon resonance measurements. Unlike for tissue culture polystyrene reference surfaces, swelling of the PDEGMA chains below the lower critical solution temperature results in the absence of paxillin and actin containing cellular filaments responsible for cell attachment. These tunable properties of very thin homopolymer PDEGMA brushes render this system interesting as an alternative thermoresponsive layer for continuous cell culture or enzyme‐free cell culture systems.

     

IrIII‐based Octahedral Metalloligands Derived Primitive Cubic Frameworks for Enhanced CO2/N2 Separation

We developed a metalloligand strategy to construct porous frameworks, viz. the combined use of Ir^III‐based octahedral metalloligands and the linear unit [Ni(cyclam)] easily afforded two isostructural complexes 1 and 2 with primitive cubic frameworks. Both complexes show good CO₂/N₂ separation property.     

工程结构静力分析和屈曲分析程序系统DDJTJQ及其应用

DDJTJQ是一个国内开发的组合结构静力分析和屈曲分析有限元程序系统,自1986年通过技术鉴定以来又有了许多发展。本文介绍该程序系统的功能和特点、求解能力以及在不同工程领域结构分析中的应用。     

Extraction-condensation method for solving large sets of equations in FE analysis

In static and dynamic analysis of a large complex structure, one may merely be interested in the stresses and displacements at some important locations. A new solution technique for structural analysis with FEM is proposed in this paper by which those important unknowns are separated from the rest. In static analysis the important unknows can be found directly. In dynamic analysis all mass and exciting forces can be condensed onto a small number of predetermined points in order to make the dynamic analysis much simplified. A large scale problem can be solved with a small capacity computer quickly.     

结构静动力屈曲问题研究进展

近几十年来，结构的静动力屈曲问题一直是力学工作者极为关注的一个前沿课题．本文总结和综述了这一研究领域的几个基本问题：屈曲问题的分类、动态屈曲问题的特点及其特征量；介绍了屈曲问题的处理方法和目前已取得的成果；总结评述了人们关心的热点问题；屈曲问题的模型分析和实验技术、动态屈曲判别准则．     

航空发动机压气机叶片振动频率与温度的关系

以某型航空发动机压气机第六级叶片为例，研究了温度对叶片振动频率的影响。发现由于温度的升高导致了材料弹性模量的下降，而弹性模量的下降又导致了叶片在发动机一定的转速范围内，除一阶振动外，其余各阶振动的动频均小于静频，因此与通常的工程处理方法不同，研究压气机叶片的动频时，应考虑温度的影响。     

厚壁圆柱壳的弹性静力分析

本文研究了考虑横向剪切影响的弹性厚壁圆柱壳的静力问题。利用变分原理得到平衡微分方程组和相应的边界条件。将平衡方程组归并成一个高阶微分方程,用数值法求出它的特征根,得到问题的解。