共查询到20条相似文献,搜索用时 15 毫秒
1.
A new rhodamine-based derivative bearing a naphthyridine group (compound 1) was synthesized as a colorimetric and fluorescent “off-on” chemosensor for Cu2+ in aqueous solutions. The sensing behaviors of 1 toward various metal ions in neutral aqueous solutions were investigated by absorption and fluorescence spectroscopies. Compound 1 is found to exhibit a significant increase in absorbance at 561 nm and an amplified fluorescence at 590 nm toward Cu2+ in a selective, sensitive and rapid manner. The quantification of Cu2+ by 1 using an absorption spectroscopy method was satisfactory in the linear working range 0.9–10 μM, with a detection limit of 5.4?×?10?8?M for Cu2+ and good tolerance of other metal ions. Upon addition of Cu2+, the spirolactam ring (colorless and nonfluorescent) of 1 was opened to ring-opened amide (red color and fluorescent) and a 1:1 stoichiochemetry for the 1-Cu2+ complex was formed with an association constant of 1.57?×?104?M?1. 相似文献
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We present a simple method to induce mechanically a long-period fibre grating in a general sing mode fibre.The transmission spectrum of the new type of grating can be tailored by changing the external applied pressure or by introducing a phase-shift in the grating.The tunability this kind of gratings exhibit will be particularly useful for the filter design. 相似文献
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We find that second-order coherence as well as a Hanbury-Brown-Twiss intensity interferometer may provide an optimal approach for eavesdropping detection in the quantum key distribution based on two-mode squeezed vacuum states. With this approach, eavesdropping can be easily detected without sacrificing extra secret bits as the test key. In addition, the efficiency of the quantum key distribution protocol is enhanced greatly. 相似文献
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Journal of Fluorescence - A series of new chemosensor molecules bearing benzothiazole-, quinoline- and phthalazine-functionalized fluorene derivatives were synthesized and their complexation... 相似文献
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Di Zhang Ruyi Zou Min Wang Meimei Chai Xubin Wang Yong Ye Yufen Zhao 《Journal of fluorescence》2013,23(1):13-19
A novel series colorimetric and off–on fluorescent chemosensors (2a, 2b, 2c) were designed and synthesized, which showed reversible and highly selective and sensitive recognition toward Fe3+ over other examined metal ions. Upon addition of Fe3+, sensors (2a, 2b) exhibit remarkably and 2c exhibits moderate enhanced absorbance intensity and color change from colorless to pink in CH3OH–H2O(1:1, v/v). The three compounds (2a, 2b, 2c) may therefore be applicable as rhodamine-based turn-on type fluorescent chemosensors. 相似文献
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A new criterion has been proposed to predict the major disruptions caused by tearing mode instabilities. According to the HL-2A experimental results, the statistical analyses are employed to investigate the relationships between MHD activities and the plasma disruptions. Two kinds of the tearing mode activities can finally cause the disruption on HL-2A operations. By introducing a new parameter, i.e. an integral of poloidal magnetic field over time, as the criterion of disruption precursor, almost all of the disruptions can be predicted. 相似文献
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1 Introduction Thelandsubsidenceeffectonundergroundpipelineissevere ,becausethesepipelinesareusuallyburiedbelowgroundabout1 .5m .Forexample,theaverageheightoflandsubsidenceis 50~ 1 0 0mminXiqinDistrict,anactivesubsidingregioninTianjin .Theaccumulatedsubsidence… 相似文献
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GuoYuhui WangYanyu LiXiaoqiang QiaoWeimin 《近代物理研究所和兰州重离子加速器实验室年报》2003,(1):109-109
A vacuum remote-control system transmits the information of the vacuum equipment‘s controlling and state by use of RS-485 series bus of intranet. The control system module VAC400 adapts MSPF149 of mixture signal process chip produced by TI, which has advantages of ultra-low-power and high-integration. This control net has the characteristics of strong function, simple structure, high reliability, strong resistance of noise, no peripheral chip, etc. The control architecture diagram is shown in Fig.1. 相似文献
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We propose a scheme for generating entangled squeezed vacuum states of electromagnetical fields. The scheme is based on cavity QED. In this scheme, an atom interacts, successively, with a classical field, two quantum cavity fields, and another classical field. By detecting the final states of the atom, the two quantum cavity fields will be projected to an entangled state. 相似文献
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Natalia A. Bumagina Elena V. Antina Anna Yu. Nikonova Mikhail B. Berezin Alexander A. Ksenofontov Anatoly I. Vyugin 《Journal of fluorescence》2016,26(6):1967-1974
3,3′,5,5′-Tetraphenyl-2,2′-dipyrromethene was described as a highly sensitive and selective Off-on fluorescent colorimetric chemosensor for Zn2+ based on the chelation-enhanced fluorescence (CHEF) effect. The reaction of dipyrromethene ligand with Zn2+ induces the formation of the [ZnL2] complex, which exhibits the increasing fluorescence in 120 fold compared with ligand in the propanol-1/cyclohexane (1:30) binary mixture. The Zn2+ detection limit was 1.4 × 10?7 М. The UV-Vis and fluorescence spectroscopic studies demonstrated that the dipyrromethene sensor was highly selective toward Zn2+ cations over other metal ions (Na+, Mg2+, Co2+, Ni2+, Fe3+, Cu2+, Mn2+, Cd2+ and Pb2+), excluding Hg2+. 相似文献
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Man Li Di Zhang Yaqi Liu Peigang Ding Yong Ye Yufen Zhao 《Journal of fluorescence》2014,24(1):119-127
A novel colorimetric and off–on fluorescent chemosensor 2 was designed and synthesized, which showed reversible and highly selective and sensitive recognition toward Cr3+ over other examined metal ions in aqueous solution. Upon addition of Cr3+, the solution of chemosensor 2 resulted in a color change from colorless to obvious pink color, these significant changes in color could be used for naked-eye detection. Chemosensor 2 exhibited a stable response for Cr3+ in the range 0–10 μM with a detection limit of 1 ppm. Furthermore, fluorescence imaging experiments of Cr3+ ions in living MGC803 cells demonstrated its value of practical applications in biological systems. 相似文献
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Herein we report a set of new water-soluble fluorescent probes (N-boronobenzyl-6-aminoquinolinium bromides, BAQBAs) sensitive to aqueous fluoride. These probes shows spectral shifts and intensity changes in the presence of fluoride, in a wavelength ratiometric and colorimetric manner, enabling the detection of fluoride concentrations at visible wavelengths, in the concentration range approximately 1-300 mM. Although the sensing mechanism is different for fluoride as compared to the other halides, we have tested the utility of these probes towards the other halides, and the results reveal that the BAQBAs are in fact potential candidates towards the sensing of the all the halides, but in different concentration ranges. As the probes are based on the boronic acid moiety, which is a well-known fluoride and sugar chelator group, we have investigated the response of sugars (such as glucose and fructose, which are present in biological fluids and foodstuffs) as interferences in fluoride detection using these probes. Interestingly, the BAQBAs show a suppressed sugar response potentially allowing for the predominant fluoride sensitivity. In addition to physiological sugars, we also have assessed the response of aqueous halides as potential interferents, or indeed analytes to be sensed, and show that the new boronic acid containing probes respond well to aqueous fluoride in the presence of a high background of other species, such as in a biological cocktail of 50 mM Glucose, 50 mM aqueous Chloride and 5 mM Fructose. 相似文献
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Journal of Fluorescence - Although cyanogen ion (CN?) plays important role in industry which also bring acute environmental pollution. More serious, trace CN? enters the human body can... 相似文献
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Di Zhang Min Wang Cuicui Wang Man Li Yong Ye Yufen Zhao 《Journal of fluorescence》2013,23(5):1045-1052
Two novel rhodamine derivatives were designed and synthesized. They were successfully characterized by HR-MS, 1H NMR and 13C NMR. They were found to exhibit a reversible colorimetric response and exhibit high selectivity and sensitivity for Hg(II) ion over other commonly coexistent metal ions. Their selectivity is excellent, and the detection of Hg(II) at ppb level is possible. The colorimetric and fluorescent response to Hg(II) can be conveniently detected even by the naked eye, which provides a facile method for visual detection of Hg(II). 相似文献
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Based on the Dyson-Schwinger approach, we propose a new method for calculating vacuum susceptibilities. As an example, the vector vacuum susceptibility is calculated. A comparison with the results of the previous approaches is presented. 相似文献
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A method of fast design and fabrication for bass-relief micro-profiles is developed by using an analytic formulation to determine the exposure distribution. Based on an equivalent exposure threshold model, the formulation is simplified for the case of bass-relief profile corresponding to the smaller exposure dose. The mask function for a microlens array is designed without iteration involved by the analytic formulation. The experiment is performed to validate the method, and the fabrication result is obtained with the profile error less than 30nm (rms). 相似文献
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A point collocation method is combined with the Bhatnagar-Gross-Krook (BGK) scheme.The point collocation method is based on reproducing kernel approximations.The BGK scheme developed is evaluated under the finite difference method framework.After the construction of local equilibrium distribution function,the second-order accurate least-square kinetic upwind method is employed to improve the accuracy.Some test cases are explored to validate this meshless method. 相似文献