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191.
Microfluidic devices with their inherent advantages like the ability to handle 10−9 to 10−18 L volume, multiplexing of microchannels, rapid analysis and on-chip detection are proving to be efficient systems in various fields of life sciences. This review highlights articles published since 2010 that reports the use of microfluidic devices to separate biomolecules (DNA, RNA and proteins) using chromatography principles (size, charge, hydrophobicity and affinity) along with microchip capillary electrophoresis, isotachophoresis etc. A detailed overview of stationary phase materials and the approaches to incorporate them within the microchannels of microchips is provided as well as a brief overview of chemical methods to immobilize ligand(s). Furthermore, we review research articles that deal with microfluidic devices as analytical tools for biomolecule (DNA, RNA and protein) separation. 相似文献
192.
High pesticide use, especially in agriculture, can lead to environmental pollution and potentially adverse health effects. As result, pesticide residues end up in different media, including water and food products, which may serve as direct routes for human exposure. There is thus a continuous drive to develop analytical methods for screening and quantification of these compounds in the different environmental media in which they may occur. Development of quantum dot (QD) based sensors for monitoring pesticides has gained momentum in recent years. QD materials have excellent and unique optical properties and have high fluorescence quantum yields compared to other fluorophores. They have thus been used in numerous studies for the development of probes for organic pollutants. In this paper we specifically review their application as fluorescence probes for pesticide detection in different media including water and in fruits and vegetables. The low detection limits reported demonstrate the potential use of these methods as alternatives to expensive and time-consuming conventional techniques. We also highlight potential limitations that these probes may present when it comes to routine application. Finally we discuss possible future improvements to enhance the selectivity and robustness of these sensors. We note that there is still a need for researchers to develop standardized QD based sensors which could lead to their commercialization and routine application. 相似文献
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194.
在C/KOH/Ni(OH)2型非对称电化学电容体系中,Ni(OH)2电极需具有快速发生电化学反应的能力与活性炭负极匹配。本文通过增加微集流体的掺杂比例.对活性物质进行球磨处理、固相掺杂碳纳米管等方法对正极进行改性研究。实验发现,增加正极微集流体的掺杂比例.可明显改善非对称电容大电流条件下的容量和循环性能;对正极活性物质进行球磨处理,有利于电极活性物质的转变.加快非对称电容的活化速度;在正极固相掺杂一定比例的碳纳米管可提高非对称电容的充放电效率和容量性质。 相似文献
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196.
研究了阴离子交换树脂对水相中有机磷酸萃取剂的吸附。 通过比较不同的离子交换树脂对水相中2-乙基己基膦酸-单-2-乙基己基酯(P507)的去除率,发现大孔强碱性阴离子交换树脂(D201-OH)从水溶液中去除P507的能力最强,去除率可达99.24%。 而且当溶液在pH=1.0时,D201-OH对P507的吸附主要是分子吸附,其吸附等温线更适用于Langmuir模型;当溶液在pH=5.0时,阴离子交换反应占主导地位,其吸附等温线更适用于Freundlich模型。 研究还表明,D201-OH对P507的吸附在20 min内即达到吸附平衡时99.8%的吸附量。 通过动力学研究表明,拟一级动力学模型(R2>0.99)更适用于描述实验数据,并且吸附速率主要受膜扩散控制。 此外,吸附-解吸附循环8次后,D201-OH的吸附能力仍然保持在93%以上。 综上所述,D201-OH是有机磷酸类萃取剂的良好吸附剂,其吸附性能高效,循环过程稳定,因此可用于实际生产过程中回收有机磷酸萃取剂。 相似文献
197.
In this study, new nanoscale photocatalyst based on silver and CNTs/TiO2 was successfully prepared by photoreduction method. The prepared Ag-CNTs/TiO2 was characterized by TEM, XRD and XPS. The photocatalytic activity was also evaluated by photocatalytic degradation of Reactive Brilliant Red X-3B dye. The results indicated that the photocatalytic efficiency of CNTs/TiO2 increased in the presence of Ag nanoparticles and the photocatalysis reaction followed a first order kinetics. The kinetic constant of Ag-CNTs/TiO2 for dye degradation was nearly 1.2 times than that of CNTs/TiO2, which indicated decorating Ag nanoparticles on CNTs/TiO2 could enhance the photocatalytic ability. 相似文献
198.
Different multicasting schemes in optical packet switched networks are discussed, including the parallel mode, serial mode, and hybrid mode multicasting schemes. Simulated modeling technique is applied to compare the network-level performance of the three multicasting schemes. A conclusion can be drawn from the results that since the hybrid-mode multicasting scheme can increase the multicast success ratio and reduce the packet retransmission times compared with the other two schemes, it is the best choice for delivering multicasting sessions in the optical packet switched networks. 相似文献
199.
GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical orbit of period 2.64 days and eccentricity 0.16.
With a typical tidal dissipation factor (Q′∼106) as that of a giant planet with convective envelope, its orbital circularization timescale under internal tidal dissipation
is around 1 Ga, at least two times less than the stellar age (> 3 Ga). A plausible mechanism is that the eccentricity of GJ
436b is modulated by a planetary companion due to their mutual perturbation. Here we investigate this possibility from the
dynamical viewpoint. A general method is given to predict the possible locations of the dynamically coupled companions, including
nearby/distance non-resonant or mean motion resonance orbits with the first planet. Applying the method to GJ 436 system,
we find it is very unlikely that the eccentricity of GJ 436b is maintained at the present location by a nearby/distance companion
through secular perturbation or mean motion resonance. In fact, in all these simulated cases, GJ 436b will undergo eccentricity
damp and orbital decay, leaving the present location within the stellar age. However, these results do not rule out the possible
existence of planet companions in nearby/distance orbits, although they are not able to maintain the eccentricity of GJ 436b.
Supported by the National Natural Science Foundation of China (Grant Nos. 10833001 and 10778603) and the National Basic Research
Program of China (Grant No. 2007CB4800) 相似文献
200.