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DNA methyltransferase (DNA MTase) can act as biomarker for many diseases and it is important to develop some new methods for sensitive detection of DNA MTase. In this work, a highly efficient electrochemiluminescence (ECL) sensor had been designed for detection of DNA MTase based on Ru(phen)32+ loaded double strand DNA (dsDNA- Ru(phen)32+) as signal tags. Ru(phen)32+ had been efficiently embed in the dsDNA produced through a simple hybridization chain reaction. First, a hairpin probe was designed, which can be specifically recognized by Dam MTase and modified with -SH at one end. It was modified on the surface of gold electrode by -SH as an immobilization probe (IP). This IP will be methylated in the present of Dam MTase and digested by DpnI following. Results in the release of capture probe (CP) which remains on the surface of gold electrode. The CP can hybridize with the single stand part of the dsDNA- Ru(phen)32+ and make the immobilization of ECL tags on the electrode surface, which results in a strong ECL signals detected. However, without the effect of Dam MTase, the hairpin structure of IP remains stable and cannot capture signal tags, and can only detecte weak ECL signals. The biosensor can detect the activity of Dam MTase in the concentration range of 0.01 U/mL to 20 U/mL with the ECL intensity and the logarithm of the concentration have a linear relationship, and the detection limit is calculated to be 7.6 mU/mL. The developed sensor has the ability to specifically detect Dam MTase, which can be differentiated from other types of DNA MTase. In addition, the designed method has good applicability to detect Dam MTase activity in serum samples and been applied to detect its inhibitor with high efficiency. 相似文献
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A. Lyaghfouri 《Annali dell'Universita di Ferrara》2003,49(1):209-262
In this paper we study the problem of seepage of a fluid through a porous medium, assuming the flow governed by a nonlinear Darcy law and nonlinear leaky boundary conditions. We prove the continuity of the free boundary and the existence and uniqueness of minimal and maximal solutions. We also prove the uniqueness of theS 3-connected solution in various situations. 相似文献
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J. P. Shannon D. W. Blinn G. A. Haden E. P. Benenati K. P. Wilson 《Isotopes in environmental and health studies》2013,49(3):179-191
Abstract Dual stable isotope analysis in the regulated Colorado River through Grand Canyon National Park, USA, revealed a food web that varied spatially through this arid biome. Down-river enrichment of δ13C data was detected across three trophic levels resulting in shifted food webs. Humpack chub δ13C and δ15N values from muscle plugs and fin clips did not differ significantly. Humpback chub and rainbow trout trophic position is positively correlated with standard length indicating an increase in piscivory by larger fishes. Recovery of the aquatic community from impoundment by Glen Canyon Dam and collecting refinements for stable isotope analysis within large rivers are discussed. 相似文献
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本文通过对蓬安县三元水库大坝外坡裂缝产生的原因分析,进而运用岩、土力学的理论与方法反算推论出了裂缝的产生不是深层坝体土滑动引起的,而是局部浅层坝体土在水的诱发作用下作蠕滑-拉裂变形所产生的。在明确了大坝裂缝产生的原因后,提出了一系列相应整治工程措施,以达到彻底根治裂缝和稳固大坝的目的。 相似文献
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The objective of this research work has been to conduct experimental measurements on a dam break flow over a horizontal dry bed in order to provide a detailed insight, with emphasis on the pressure loads, into the dynamics of the dam break wave impacting a vertical wall downstream the dam. The experimental setup is described in detail, comprising state of the art miniaturized pressure sensors, high sampling rate data acquisition systems and high frame-rate video camera. It is a 1:2 scale of the highly cited (Lee et al., 2002, Journal of Fluids Engineering, 124) article experimental apparatus. Kinematics has been analyzed focusing on the free surface and wave front evolution. Experimental observations regarding liquid height and wave front speed have found to be in agreement with existing literature. This agreement enables the authors, assuming a similar framework, to discuss the measured pressure loads as a consequence of the dam break wave front impacting on the downstream wall. These loads show a substantial variability which has been statistically characterized. The measured quantities have been compared with the scarce available data in the literature, whose consistency is discussed. Measurements have been conducted with two filling heights. Scaling effects for such heights are also analyzed. As a direct result of the present initiative, an extensive set of data for computational tools validation is provided as Supplementary Materials, including pressure signals, wave height measurements and experimental videos. 相似文献