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101.
N‐(2,4‐dinitrophenyl)‐proline and N‐(2,4‐dinitrophenyl)‐serine were enantiomerically resolved on the BSA chiral stationary phase by HPLC in reversed‐phase mode. Effects of chromatographic conditions on enantioseparation and elution order have been investigated in detail. For these two samples, reversal of enantiomer elution order was observed by changing buffer pH, the content of acetonitrile, or alcohol modifiers in mobile phase, which is firstly reported in the BSA chiral stationary phase studies. More interestingly, combined effect between buffer pH and the content of acetonitrile was also observed. In addition, coelution range of enantiomers varied along with the content of acetonitrile in mobile phase.  相似文献   
102.
Water is an important component in living systems and deserves better understanding in chemistry and biology. However, due to the difficulty of investigating the water functions in protein structures, it is usually ignored in computational modeling, especially in the field of computer‐aided drug design. Here, using the potential of mean forces (PMFs) approach, we constructed a water PMF (wPMF) based on 3946 non‐redundant high resolution crystal structures. The extracted wPMF potential was first used to investigate the structure pattern of water and analyze the residue hydrophilicity. Then, the relationship between wPMF score and the B factor value of crystal waters was studied. It was found that wPMF agrees well with some previously reported experimental observations. In addition, the wPMF score was also tested in parallel with 3D‐RISM to measure the ability of retrieving experimentally observed waters, and showed comparable performance but with much less computational cost. In the end, we proposed a grid‐based clustering scheme together with a distance weighted wPMF score to further extend wPMF to predict the potential hydration sites of protein structure. From the test, this approach can predict the hydration site at the accuracy about 80% when the calculated score lower than ?4.0. It also allows the assessment of whether or not a given water molecule should be targeted for displacement in ligand design. Overall, the wPMF presented here provides an optional solution to many water related computational modeling problems, some of which can be highly valuable as part of a rational drug design strategy. © 2012 Wiley Periodicals, Inc.  相似文献   
103.
Amidoxime (AO)/amine co-functionalized polypropylene fiber adsorbents were prepared. The all-polymeric structures were characterized by using Fourier transform infrared spectroscopy (FTIR), optical microscope, contact angle meter and electron spin resonance (ESR) analysis methods, confirming the grafting, modification, and amidoximation stages gravimetrically, spectroscopically, and visually. The properties for the removal of uranyl(VI) from aqueous solutions were investigated. For amidoxime (AO) fiber, high adsorption rate was observed within the first 30 minutes and the plateau value of 40.6% uranium loading (0.0812 mg/g) was reached at around 30 minutes. The adsorption equilibrium for AO/amine fiber was attained within 20 minutes, resulting in the adsorption of 92.6% uranium loading (0.185 mg/g). The percentage of adsorption increases with increasing pH value (2–6), reaches a maximum at pH 6.0 and then remains almost constant for AO/amine fiber, whereas reduces slightly for AO fiber.  相似文献   
104.
A novel cationic gemini surfactant has been readily synthesised in 70 % total yield. The functional gemini surfactant can act both as an emulsifier and an atom transfer radical polymerisation (ATRP) initiator in mini-emulsion polymerisation of methyl methacrylate (MMA), in which no other emulsifier was required. 1-(Dimethylamino)dodecane (N,N-dimethyldodecylamine, DMDA) was found to be a good ligand in the activator generated by electron transfer (AGET) ATRP reaction. Kinetic studies indicated that the polymerisation featured controlled/living radical polymerisation.  相似文献   
105.
The unique features of high porosity, shape selectivity, and multiple active sites make metal–organic frameworks (MOFs) promising as novel stationary phases for high‐performance liquid chromatography (HPLC). However, the wide particle size distribution and irregular shape of conventional MOFs lead to lower column efficiency of such MOF‐packed columns. Herein, the fabrication of monodisperse MOF@SiO2 core–shell microspheres as the stationary phase for HPLC to overcome the above‐mentioned problems is reported. Zeolitic imidazolate framework 8 (ZIF‐8) was used as an example of MOFs due to its permanent porosity, uniform pore size, and exceptional chemical stability. Unique carboxyl‐modified silica spheres were used as the support to grow the ZIF‐8 shell. The fabricated monodisperse ZIF‐8@SiO2 packed columns (5 cm long × 4.6 mm i.d.) show high column efficiency (23 000 plates m?1 for bisphenol A) for the HPLC separation of endocrine‐disrupting chemicals (bisphenol A, β‐estradiol, and p‐(tert‐octyl)phenol) and pesticides (thiamethoxam, hexaflumuron, chlorantraniliprole, and pymetrozine) within 7 min with good relative standard deviations for 11 replicate separations of the analytes (0.01–0.39, 0.65–1.7, 0.70–1.3, and 0.17–0.91 % for retention time, peak area, peak height, and half peak width, respectively). The ZIF‐8@SiO2 microspheres combine the advantages of the good column packing properties of the uniform monodisperse silica microspheres and the separation ability of the ZIF‐8 crystals.  相似文献   
106.
107.
用FeCl3·6H2O催化3-甲基环己酮与丙酮酸乙酯交叉羟醛缩合,制得2-(2-氧代-4-甲基环己叉基)丙酸乙酯和7a-羟基薄荷内酯,皂化后用硼氢化钠还原、酸化制得(±)-薄荷内酯,产率为51%。考察了3-甲基环己酮的烯醇式异构化的位置选择性和粗产物中(±)-薄荷内酯与(±)-异薄荷内酯异构体的比例。  相似文献   
108.
采用溶液自由基聚合,合成甲基丙烯酰氧乙基磷酰胆碱(MPC)-甲基丙烯酰氧丙基三甲氧基硅(TSMA)二元共聚物(PMT82),将其涂覆在戊二醛交联壳聚糖(CS-GA)表面,通过三乙胺蒸汽催化处理获得具有仿细胞外层膜结构(CS-GA-PMT82b)的表面.用动态接触角(DCA)、X-射线光电子能谱(XPS)对改性后交联壳聚糖表面的亲疏水性、元素组成等进行表征,并通过血小板黏附实验对其抗凝血性进行评价.研究结果表明,这种利用涂覆催化交联的方式将含有三甲氧基硅可交联基团的磷酰胆碱聚合物交联固定在壳聚糖表面,获得了较为稳定的仿细胞外层膜结构的CS-GA-PMT82b涂层表面.与壳聚糖相比,改性后壳聚糖的血小板黏附显著减少,抗凝血性能显著提高.这种改善材料的方式有望成为生物医用材料表面改性领域的有效的新手段.  相似文献   
109.
针对TE化工过程高度非线性、复杂性的特点,本文提出了一种基于相关分析和最小二乘支持向量机对TE过程进行多模型建模方法,以提高模型性能。首先对TE过程采用相关分析法划分为3个子系统,对每个子系统分别采用基于C-均值聚类的最小二乘支持向量机建模和基于k均值聚类的最小二乘支持向量机多模型建模。实验表明,基于K-均值聚类的多模型建模能简化计算、提高模型精度、并且能更好的预测模型输出。  相似文献   
110.
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