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We describe a simple and homogenous fluorimetric method for sensitive determination of DNA. It is based on target-triggered isothermal cycling and a cascade exponential amplification reaction that generates a large amount of a G-quadruplex. This results in strong fluorescence signal when using thioflavin T as a G-quadruplex-specific light-up fluorescent probe. Tedious handling after amplification is widely eliminated by the addition of thioflavin T. No other exogenous reagent is required. This detection platform is inexpensive and rapid, and displays high sensitivity for target DNA, with a detection limit as low as 91 pM.
相似文献33.
Bi3TiNbO9:Er3+:Yb3+ (BTNEY) thin films were fabricated on fused silica by pulsed laser deposition. It was demonstrated that different laser fluence and substrate temperature during growth of BTNEY upconversion photoluminescence (UC-PL) samples control the film’s grain size and hence influences the UC-PL properties. The average grain size of BTNEY thin films deposited on fused silica substrates with laser fluence 4, 5, 6, and 7 J/cm2 are 30.8, 35.9, 40.6, and 43.4 nm, respectively. The 525 nm emission intensities increase with the deposition laser fluence and the emission intensities of BTNEY thin film deposited under 700 and 600 °C are almost 24 and 4 times, respectively, as strong as those of samples under 500 °C. The grain size of BTNEY thin film increases with the increasing temperature. UC-PL of BTNEY films is enhanced by increasing grain size of the films. 相似文献
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A Direct‐SIMPLE scheme is further extended for numerical simulations of heat and species mass transfer, and liquid flow behaviours in solidification processes of shaped alloy castings under various electromagnetic (EM) fields, based on a binary continuum model (a solidification transport phenomena/processes (STP)‐based dendrite solidification model). Unlike in a SIMPLE scheme, no iterative computations are needed to achieve the final pressure and velocity corrections in the extended Direct‐SIMPLE procedure, therefore extremely high computational efforts can be avoided. Using three different types of model alloys, pseudo‐binary In718 base‐4.85 wt% Nb, γ(TiAl)‐55 at% Al and Al‐4.5 wt% Cu systems, sample computations for solving strongly coupled solidification transport phenomena in directionally solidifying shaped castings under static and harmonic EM‐fields of different strengths are carried out, to demonstrate the feasibility and efficient calculation performance of the present model and numerical methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Chunjuan Cui Jun Zhang Kun Wu Youping Ma Lin Liu Hengzhi Fu 《Physica B: Condensed Matter》2012,407(17):3566-3569
Ni–Ni3Si composites are prepared by the Bridgman directional solidification technology under different growth conditions, aiming to improve the ductility of the Ni3Si compound and investigate the relationship between solidification microstructure and the properties. Microstructure of the Ni–Ni3Si hypoeutectic in situ composites transforms from regular lamellar eutectic to cellular structure then to dendritic crystal with the increase of the solidification rate. Ni–Ni3Si eutectic composites display regular lamellar eutectic structure at the solidification rate R=6.0–40.0 μm/s and the lamellar spacing is decreased with the increase of the solidification rate. Moreover, the Ni–Ni3Si hypoeutectic composites present lower micro-hardness than pure Ni3Si, which indicate Ni–Ni3Si hypoeutectic composites have higher ductility, whereas the ductility of the Ni–Ni3Si eutectic composites has scarcely been improved. This is caused by the formation of the metastable Ni31Si12 phase in the Ni–Ni3Si eutectic composites. 相似文献
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针对聚合物材料在使用过程中难以检测的损伤,人们引入了自修复概念。本文就近年来自修复聚合物材料的研究进展作了系统综述。根据自修复过程是否使用修复剂,聚合物材料(包括聚合物基复合材料)的自修复可分为外援型和本征型两大类。外援型自修复借助于外加修复剂实现自修复,主要包括埋植微胶囊化修复剂和埋植中空纤维化修复剂两种方法。微裂纹的破坏使微胶囊或中空纤维释放修复剂,修复剂发生化学反应,键合裂纹面,达到自修复的效果。这种方法相对比较简单,修复效果较好,但不能重复进行,而且可选用的修复剂种类有限。本征型自修复则借助于体系内存在的Diels-Alder反应、动态共价化学、双硫键反应、含有氢键的超分子结构、π-π堆叠及离子聚合物等来完成,这些特殊的分子结构所涉及的化学反应是可逆的。本征型自修复聚合物材料的制备过程较为复杂,但这种自修复可以反复多次有效,从而延长了聚合物材料的使用寿命。本文针对以上两大类自修复聚合物材料体系的特点和应用进行综述,并展望其发展方向。 相似文献
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水性聚氨酯硬段含量对其氢键相互作用及性能的影响 总被引:2,自引:0,他引:2
异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)作为硬段,合成了水性聚氨酯。 研究了硬段含量(质量分数)对乳液稳定性、膜耐热和力学性能等的影响。 当硬段质量分数低于26%时,乳液贮存稳定性较差。 随着硬段含量增加,聚氨酯膜拉伸强度迅速增加,断裂伸长率略有降低;红外光谱显示,自由的N-H伸缩振动峰强度减弱,氢键化N-H的振动峰强度增加;同时C=O伸缩振动峰整体向低波数方向移动,C=O伸缩振动峰峰形有明显的变化;DSC测试在50~125 ℃出现明显的氢键解离现象,吸热峰增强,证实了氢键作用力随着硬段含量的增加逐渐增强。 TG测试表明,水性聚氨酯硬段和软段分步解离,随着硬段含量的增加,硬段分解温度降低,水性聚氨酯耐热性能下降。 相似文献
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Mi Ouyang Lina Zhang Yuwen Li Lu Chen Bowen Tao Weijun Li Xiaojing Lv Ru Bai Hengzhi Zhou Alexander Nekrasov Cheng Zhang 《Journal of polymer science. Part A, Polymer chemistry》2023,61(1):56-66
Two reported D-A-D monomers based on 3,4-ethylenedioxythiophene (EDOT) were selected for electrochemical copolymerization to obtain copolymer film, named pRG. Then, a soluble polymer poly[3,4-ethylenedioxythiophene-alt-3,4-bis([2-ethylhexyl]oxy)thiophene] (pEA) based on the EDOT derivative was screened out, which is complementary to the absorption trough of the pRG film in visible region and matched with its working potential. The bilayer composite film pRG/pEA was obtained by spinning pEA basement membrane on fluorine doped tin oxide (FTO) coated glass surface, and then in situ electrochemical polymerization of pRG film. Compared to the pRG monolayer film, the bilayer composite film shows a more saturated black color in the neutral state and significant improvement on cyclic stability (only decreased by 1.7% after 250 cycles, while pRG film decreased by 17.1%). The introduction of pEA buffer layer not only achieves the full spectral absorption of the composite film in the visible region, but also significantly improves the cyclic stability of the bilayer composite film. The assembled EC prototype device based on the pRG/pEA composite film exhibits a “black to high transmission” reversible switch. Finally, this method combining electrochemical copolymerization, spin-coating, lamination and other methods provides a new research idea for designing and preparing black to transmissive electrochromic materials. 相似文献