分子印迹技术研究进展

分子印迹技术是制备对特定目标分子具有特异性识别能力的高分子材料的技术,所制备的高分子材料被称为分子印迹聚合物.分子印迹聚合物因具有预定性、识别性和实用性三大优点已广泛应用于分离、模拟抗体与受体、催化剂以及仿生传感器等方面和领域,显示出了广泛的应用前景.作者对分子印迹技术的发展历史、基本原理、分类、应用现状以及一些新的研究热点进行了综述.     

分子印迹技术研究进展

分子印迹是制备具有分子特异识别功能聚合物的一种技术。本文从分子印迹聚合物的识别机理、分子印迹聚合制备条件和制备技术三个方面综述了分子印迹的研究进展,最后展望了分子印迹发展前景。引用文献66篇。     

分子印迹-仿生传感器的研究进展

分子印迹技术是制备具有选择性分子识别能力聚合物(分子印迹聚合物)的新兴化学合成技术。分子印迹聚合物的一个重要应用是在生物传感器中取代生物分子作为识别元件,研制耐受性强、低成本的分子印迹仿生传感器。综述了分子印迹技术的基本原理及其在仿生传感器方面的应用研究现状,并对分子印迹仿生传感器的发展前景进行了评述。引用文献24篇。     

环丙沙星分子印迹聚合物的合成及识别性能研究

采用分子印迹技术合成了以环丙沙星为印迹分子,以甲基丙烯酸和4-乙烯基吡啶同时为功能单体的分子印迹聚合物。运用平衡结合实验研究了印迹聚合物的吸附特性和选择识别能力。Scatchard分析表明,在所研究的浓度范围内,分子印迹聚合物中形成了两类不同的结合位点。底物选择实验表明,这种聚合物对环丙沙星呈现高的选择结合能力。     

水相识别分子印迹技术

在各种基于超分子方法的仿生识别体系中,分子印迹聚合物已经证明是一种有潜力的合成受体,受到了广泛的关注。传统的分子印迹技术通常是在有机溶剂中制备对小分子具有选择性的印迹聚合物,而在水相中制备及识别生物大分子的研究仍具有相当的挑战性。从小分子到生物大分子、从有机相到水相,反映了分子印迹技术的发展趋势。本文对最近几年分子印迹在水相制备与识别方面的最新进展进行了总结与评述,探讨了水相识别印迹聚合物的设计策略与制备方法;着重介绍了水相识别技术在固相萃取、色谱固定相、药物控释、中药有效成份提取以及生物分子识别等方面的应用;指出了提高水相识别选择性的途径并对其将来的发展进行了建议与展望。     

分子印迹技术用于模拟酶及分子反应器的研究进展

分子印迹技术是制备特异性分子识别材料的新技术. 分子印迹聚合物(Molecularly-imprinted polymer, MIP)具有可同酶相媲美的选择性识别能力, 能够催化手性及区域选择性的反应, 是一种新型的分子反应器; 同时MIP具有良好的化学和物理稳定性, 因而在替代酶用于某些苛刻条件下的催化反应方面有良好的应用前景. 就近年来利用MIP模拟酶催化有机合成反应, 以及利用MIP作为分子反应器反面的研究进展进行了综述.     

分子印迹水相分离技术及其在分析化学中的应用

分子印迹分离技术通过模拟抗体-抗原相互作用原理,专一地与目标分子互补性结合,从而将目标分子与杂质分离,是一种非常具有发展前景的分离技术。传统的分子印迹技术通常是在有机相中制备对印迹分子具有选择性的印迹聚合物,然而分子印迹技术的实际应用环境大多是水相体系。近年来,分子印迹水相分离技术受到了科学工作者的广泛关注。本文分别从以下几个方面总结了分子印迹水相分离技术的最新研究进展:水相中分子印迹聚合物的设计原理与合成方法;印迹聚合物在水相中的作用机制;印迹水相分离技术在分析化学中的应用。最后讨论了该项技术现存的问题,并对其未来发展进行了展望。     

分子印迹技术在蛋白质识别中的应用进展

分子印迹技术是一种制备具有分子识别能力的聚合物的有效技术,已经广泛应用于制备对小分子具有选择性的分子印迹聚合物,但制备能够特异性识别生物大分子--蛋白质的分子印迹聚合物的研究仍然具有挑战性。本文讨论了制备蛋白质分子印迹聚合物的难点,评述了目前印迹蛋白质的方法及各自的优缺点,展望了蛋白质印迹技术的发展趋势。     

分子印迹电化学传感器

分子印迹电化学传感器能够选择性识别并检测特定目标化合物,因其设计简单、灵敏度高、价格低廉、携带方便、易于微型化和自动化等优点,在临床诊断、环境监测、食品分析等方面越来越受到人们的关注.本文作者主要论述分子印迹技术与电化学技术相结合构建分子印迹电化学传感器,包括分子印迹电化学传感器的种类,以及电化学方法制备分子印迹聚合物膜的常用单体等.对分子印迹电化学传感器领域新出现的分子印迹聚合物-纳米材料复合物以及纳米结构分子印迹聚合物也一并做了评述.     

分子印迹聚合物的制备及其传感器应用研究

分子印迹技术于近十年内得到了飞速的发展,已经成为当前研究的热点之一.本文主要介绍了分子印迹聚合物的原理以及一些常用制备方法.分子印迹聚合物的一个重要应用是在化学传感器中作为识别元件,研制稳定、低成本的分子印迹传感器.分子印迹聚合物在传感器领域的应用是分子印迹技术的一个重要方面,本文综述了分子印迹聚合物在化学传感器方面的应用研究现状,并对分子印迹传感器的发展前景进行了评述.     

REGULATION OF NITRATE REDUCTASE ACTIVITY IN RICE

The properties of NR from rice varieties Yuanfengzao and Jingyin 127 are the same in molecular weight of native enzyme and subunit, optimum pH, K_m value for substrates NO_3~- and NADH, stability in vitro and immunological characteristics. The decay rate in vitro of the activity of the partially purified NR from Yuanfengzao is 20％ lower than that from Jingyin 127. The results from antiserum titration and rocket immunoelectrophoresis indicated that the amount of NR in Yuanfengzao is about 1.5 times more than that in Jingyin 127. Further study on in vivo incorporation of ~3H-labeled amino acids into NR revealed that the rate of NR synthesis in Yuanfengzao is obviously higher than that in Jingyin 127. In vitro translation of mRNA showed that the products of NR-mRNA per unit of total mRNA of Yuanfengzao is much more than that of Jingyin 127. It is concluded that, therefore, NR activity in rice is regulated through NR synthesis and NR-inhibitory protein(s) system, the former is further controlled at the lev     

中低变质程度煤显微组分结构的13 C-NMR研究

利用13C-NMR核磁共振技术对中低变质程度煤显微组分（镜质组和惰质组）的分子结构进行了研究,计算了5种煤9个显微组分的13C-NMR结构参数,获得了样品的结构特征及变化规律。结果表明,惰质组结构中芳构化程度要高于镜质组;脂碳数量则少于镜质组,芳环上的烷烃侧链也没有镜质组长;随着煤变质程度的提高,煤分子中芳构化程度不断提高,但惰质组的芳香度随变质程度变化的规律明显不如镜质组;在中低变质阶段,对煤化进程起主导作用的的是芳构化作用而不是环缩合作用,但在惰质组中脂碳断裂形成芳环的现象不明显。惰质组中含氧官能团的总量要低于同等变质程度的镜质组。     

五羰基合铁分子化学键特性的研究

We have found from experimental data that, in the iron pentacarbonyl molecule, the length of Fe-C bond in axial is shorter than that in planar, but the bond is weaker; the bond distances of C-O of both planar and axial are equal, while the bond strengths are different. This is against the traditional view of “the shorter the bond is, the stronger the bond will be”. We have got through calculation and research, that the main cause of such difference is that the effects of the backdonor of Fe atom′s electrons to C-O bonds in axial and planar are different. The shorter the Fe-C bond is, the more effective the backdonor (or transfer) of electrons is. So that the population between Fe and C in axial are less than those in planar, so the bond is weaker, and the C-O bonds have gained more backdonor electrons than those in planar, thus the bond is stronger.     

Baseline changes in an isothermal titration microcalorimeter

Summary Isothermal titration microcalorimeters are submerged in an ambience at constant temperature and, this is the reason why there should not be variations in the baseline; but the experimental measures show that, in some cases, it is produced a jump in the baseline after the liquid injection. In this paper, it is studied the origin of this variation of the baseline in order to avoid it, if it is possible, or correct it and thus, to determine with the minimum error the amounts of energy or power developed in the energetic process that is being studied. The experimental results that are shown support the hypothesis that states that the cause of the baseline jump in an isothermal microcalorimeter is the variation of the thermal coupling between the content of the mixture cell and the axis of the stirrer, which is coupled, at the same time, with an area with a temperature slightly lower (in this case) than the thermostat temperature. This jump is independent from the dissipation and it always has the same sign. The magnitude of the baseline jump is variable and it mainly depends on the volume that the liquid content in a cell reaches and the placement of the stirrer within the cell, that can be changed in the handling process.     

Shrinkability of ethylene vinyl acetate/polyurethane blends and their characterization

Heat shrinkability of the polymer, which depends on the elastic memory, is being utilized in various applications, mainly in the field of encapsulation. The elastic memory is introduced into the system in the form of an elastomeric phase. Here the blends of ethylene vinyl acetate and polyurethane were studied with reference to their shrinkability, introducing crosslinking in both the phases. It is found that with increase in elastomer content the shrinkage increased to a certain level and then decreased. With increase in cure time shrinkage is decreased. It is seen that high‐temperature (HT) stretched samples showed higher shrinkage than room temperature (RT) stretched one. Generally, the crystallinity of the HT stretched sample is higher than that of low‐temperature stretched sample, which is again higher than that of original sample. From high temperature differential scanning calorimetry it is found that with increase in PU content stability towards oxygen is increased and further high temperature processing decreases the initial degradation temperature but enhances the rate of degradation. From scanning electron microscopy it is seen that an HT stretched sample is more elongated than an RT stretched one. Copyright © 2000 John Wiley & Sons, Ltd.     

5-Hydroxymethylcytosine, the sixth base of the genome

5-Hydroxymethylcytosine (hmC) was recently discovered as a new constituent of mammalian DNA. Besides 5-methylcytosine (mC), it is the only other modified base in higher organisms. The discovery is of enormous importance because it shows that the methylation of cytosines to imprint epigenetic information is not a final chemical step that leads to gene silencing but that further chemistry occurs at the methyl group that might have regulatory function. Recent progress in hmC detection--most notably LC-MS and glucosyltransferase assays--helped to decipher the precise distribution of hmC in the body. This led to the surprising finding that, in contrast to constant mC levels, the hmC levels are strongly tissue-specific. The highest values of hmC are found in the central nervous system. It was furthermore discovered that hmC is involved in regulating the pluripotency of stem cells and that it is connected to the processes of cellular development and carcinogenesis. Evidence is currently accumulating that hmC may not exclusively be an intermediate of an active demethylation process, but that it functions instead as an important epigenetic marker.     

脱发白发与微量元素关系研究

利用火焰原子吸收法测定了中国银行韶关节市分行４５８名职工头发中Ｃｕ，Ｆｅ，Ｚｎ，Ｃａ含量，运用统计学方法求出该人群中正常者与白发，脱发者Ｃｕ，Ｆｅ，ＺｎＣａ的特征含量，通过数据比较可看出，白发者Ｃｕ，Ｆｅ，Ｚｎ，Ｃａ的含量均低于正常组，而脱发者与正常组较接近，经相关性检验，证明了Ｃｕ，Ｆｅ，Ｚｎ，Ｃａ偏低的血发存在的相关性，与脱发没有相关性，经过性别比对，女性发中Ｃｕ，Ｆｅ，Ｚｎ，Ｃａ含量均高于男     

环境铅暴露对儿童智能与行为的影响

环境铅暴露对儿童的危害已成为世界范围内一种严重的公共卫生问题。既往的研究表明环境铅暴露对儿童的智力发育将产生不良影响 ,尤其是对于婴儿 ,铅暴露是影响其精神发育的决定因素之一 ;长期的铅暴露具有累加作用 ,其毒害作用也是累加的 ;铅暴露又是导致儿童行为异常的因素之一 ;大量研究显示儿童多动症与儿童铅暴露水平有关。此外 ,铅暴露还可能影响部分儿童运动功能的发育。     

Investigation of dipolar reorientation dynamics of pure bulk polymers using second harmonic generation

Second harmonic generation (SHG) in three corona-poled, pure, bulk polymers is studied as a function of temperature. It is found that this technique readily yields dynamical information that is complementary to that obtained from the technique of dielectric relaxation (DR). The SHG results are compared to those from DR in the same temperature ranges above T_g. It is found that in the temperature ranges examined, the relaxation times obtained from SHG are several orders fo magnitude longer than those measured by dielectric relaxation. This is explained as being due to the strong correlation between oriented dipoles and to trapped charges injected by the poling process. Fitting measured data to the Williams-Landau-Ferry (WLF) equation indicates that more free volume is needed in SHG for dipolar reorientation than is needed in DR. An SHG relaxation elongation phenomenon at constant temperature is found to occur in the pure bulk polymers and is similar to that found in chromophore-doped polymers previously studied. The SHG technique is developed as a new tool to directly study the reorientational dynamics of polar polymer segments. © 1994 John Wiley & Sons, Inc.     

Peak capacity optimization in comprehensive two dimensional liquid chromatography: a practical approach

In this work we develop a practical approach to optimization in comprehensive two dimensional liquid chromatography (LC x LC) which incorporates the important under-sampling correction and is based on the previously developed gradient implementation of the Poppe approach to optimizing peak capacity. The Poppe method allows the determination of the column length, flow rate as well as initial and final eluent compositions that maximize the peak capacity at a given gradient time. It was assumed that gradient elution is applied in both dimensions and that various practical constraints are imposed on both the initial and final mobile phase composition in the first dimension separation. It was convenient to consider four different classes of solute sets differing in their retention properties. The major finding of this study is that the under-sampling effect is very important and causes some unexpected results including the important counter-intuitive observation that under certain conditions the optimum effective LC x LC peak capacity is obtained when the first dimension is deliberately run under sub-optimal conditions. In addition, we found that the optimum sampling rate in this study is rather slower than reported in previous studies and that it increases with longer first dimension gradient times.