共查询到17条相似文献,搜索用时 15 毫秒
1.
Zhihong XuAuthor Vitae Like ZhangAuthor VitaeRui GuoAuthor Vitae Tiancheng XiangAuthor VitaeChangzeng WuAuthor Vitae Zhi ZhengAuthor VitaeFengling YangAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):546-552
A new rhodamine B derivative colorimetric and fluorescent sensor (1) was synthesized by condensation reaction of rhodamine B hydrazide and 2,4-dihydroxybenzaldehyde, which showed reversible and highly selective and sensitive recognition toward Cu2+ over other examined metal ions. Upon addition of Cu2+, sensor 1 exhibits remarkably enhanced absorbance intensity and color change from colorless to pink in DMSO and MeCN aqueous buffer solution or pure MeCN, and shows significant off-on fluorescence accompanied by color changes from colorless to orange in MeCN. The sensor 1 was also successfully applied to the determination of Cu2+ in water samples. 相似文献
2.
Zhi-Qiang HuAuthor Vitae Yong-Cheng FengAuthor VitaeHe-Qing HuangAuthor Vitae Lei DingAuthor VitaeXiao-Ming WangAuthor Vitae Cun-Sheng LinAuthor VitaeMing LiAuthor Vitae Cui-Ping MaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(1):428-432
A Rhodamine-based fluorescent and colorimetric chemosensor for Fe3+ ion, acetyl rhodamine-hydroxamate (ARH), was designed and synthesized. Upon mixed with Fe3+ in CH3CN-H2O (1:1, v/v), the spirolactam of ARH was opened, which resulted in the dramatic enhancement of both fluorescence and absorbance intensity as well as the color change of the solution. Background metal ions showed small or no interference with the detection of Fe3+. The Job's plot indicated the formation of 1:1 complex between ARH and Fe3+. Confocal laser scanning microscopy experiments showed that ARH could be used to detect Fe3+ in living cells. 相似文献
3.
Guoqiang YangAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):848-853
A new fluorescent excited state intramolecular proton transfer compound, 2-(2-hydroxy-4-carbaldehydephenyl)benzoxazole (HCPBO), has been synthesized for the detection of Cu2+, based on its fluorescence quenching. In molecular monodispersed solution, the recognition selectivity for Cu2+ was poor as Co2+ and Ni2+ gave similar results in fluorescence quenching. However, the nanoparticles of HCPBO, prepared in ethanol-water (1:4, v/v), greatly enhanced the recognition selectivity for Cu2+. The mechanism was discussed as energy transfer (ET), energy migration (EM) and the more quantity of formed HCPBO-Cu2+ complex than other metal ions in the nanoparticle conditions enhanced the recognition selectivity for Cu2+ together. 相似文献
4.
Yu WangAuthor Vitae XueYan HuAuthor VitaeLei WangAuthor Vitae ZhuoBin ShangAuthor VitaeJianBin ChaoAuthor Vitae WeiJun JinAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(1):126-131
A new acridine fluoroionophore containing two diethanolamine ligands, 4,5-bis(N,N-di (2-hydroxyethyl)iminomethyl)acridine (BHIA), was designed and synthesized based on the fluorophore-spacer-receptor format. And its fluorescent sensing behavior towards metal ions was investigated in buffered aqueous media. The presence of Cd2+ induces the formation of a 1:1 ligand/metal complex at neutral pH, which exhibits enhanced emission at 454 nm. The fluorescence intensity is linear with the Cd2+ concentration in the range of 1.0 × 10−6 to 3.0 × 10−5 M (R = 0.9967). Experimental results show a low interference response towards other metal ions. The selective switch-on fluorescence response of BHIA to Cd2+ makes it suitable for sensing of Cd2+ in aqueous solution. The detection limit is 1.3 × 10−7 M. Moreover, the results indicated that BHIA was a reversible chemosensor for Cd2+, which makes it attractive for sensing applications. 相似文献
5.
Yangyang ZhangAuthor VitaeWen ShiAuthor Vitae Duan FengAuthor VitaeHuimin MaAuthor Vitae Yan LiangAuthor VitaeJianru ZuoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(1):261-265
Exposure to mercury causes severe damage to plants, animals and even humans. Concern over mercury toxicity has encouraged the development of efficient, sensitive, and selective methods for the in vivo detection of mercury. Although a variety of studies have been published describing fluorescence imaging of mercury in animal cells and tissues, no in vivo monitoring has been developed for plant systems until now. In this paper, we report the semi-quantitative fluorescence imaging of Hg2+ ions in a common model plant Arabidopsis thaliana (A. thaliana), with rhodamine B thiolactone (RBS) as a novel Hg2+ probe. The experimental results show that RBS is plant cell wall and cell membrane permeable, and the probe responds selectively to Hg2+ ions instead of the other species in plant systems. Real-time monitoring of Hg2+ absorption in roots of A. thaliana by RBS shows that saturation of Hg2+ uptake could occur in a short period of 3 days at most. The transportation and accumulation of Hg2+ ions in roots of A. thaliana have also been studied, revealing that most of Hg2+ ions reside in root cap and meristematic zone, and only a small amount of Hg2+ ions can reach the maturation zone. This indicates that the interaction of Hg2+ ions with any Hg2+-philic species including proteins in these regions may be responsible for plant poisoning and even death. 相似文献
6.
采用深海适冷菌Pseudoalteromonas sp. SM9913分泌的胞外多糖(EPS)分别对Pb2+和Cu2+进行吸附,研究了多糖用量、pH、吸附时间和共存离子对EPS吸附性能的影响及EPS对Pb2+和Cu2+的吸附热力学.结果表明,EPS对Pb2+和Cu2+的吸附量随EPS投加量的增加而减小.EPS对Pb2+和Cu2+的最佳吸附pH分别为4.5~5.5和4.5~6.0. EPS对Cu2+的吸附平衡时间为90 min,对Pb2+的吸附平衡时间则长达180 min.共存离子Ca2+、Mg2+、Na+、K+的加入均降低了EPS对Pb2+的吸附量,Ca2+、Mg2+的加入降低了EPS对Cu2+的吸附量,但低浓度的Na+和实验范围浓度的K+不仅没有降低反而增加了EPS对Cu2+的吸附量.Freundlich和Dubinin-Radushkevich方程均能较好地描述SM9913胞外多糖吸附Pb2+和Cu2+的热力学过程,由Dubinin-Radushkevich方程得到SM9913胞外多糖对Pb2+和Cu2+的最大吸附量分别为243.3 mg/g (10℃) 和36.7 mg/g (40℃).胞外多糖吸附金属离子前后的红外光谱分析表明,多聚糖中C—O—C、乙酰基和羟基是起主要吸附作用的官能团. 相似文献
7.
Single quantum dot-micelles coated with gemini surfactant for selective recognition of a cation and an anion in aqueous solutions 总被引:3,自引:0,他引:3
The synthesis of quantum dot coated with cetyltrimethyl ammonium bromide (CTAB) and gemini surfactant [C12H25N+(CH3)2(CH2)4(CH3)2N+C12H25]·2Br− (C12-4-12) in aqueous solution have been described. It is characterized by photoluminescent spectroscopy, UV–vis spectroscopy and transmission electron microscopy (TEM), etc. In comparison with CTAB-coated QDs, the QDs coated with C12-4-12 respond selectively to both transition metal ion copper and fluoride ion in aqueous media. When Cu2+ is bound to C12-4-12-coated QD micelles, the fluorescence intensity is quenched. Linear relationships are found between the relative fluorescence intensity and the concentration of Cu2+ in the range 0–500 μM, which is best described by a Stern–Volmer-type equation. Meanwhile, it is found that F− enhanced the luminescence of the C12-4-12-coated QD micelles in a concentration dependence that is described by a Langmuir binding isotherm equation in the range 0–300 μM. The limits of detection of Cu2+ and F− are 1.1 and 0.68 μM, respectively. The possible mechanism is discussed. 相似文献
8.
A series of Bi3+ and Gd3+ doped ZnB2O4 phosphors were synthesized with solid state reaction technique. X-ray diffraction technique was employed to study the structure of prepared samples. Excitation and emission spectra were recorded to investigate the luminescence properties of phosphors. The doping of Bi3+ or Gd3+ with a small amount (no more than 3 mol%) does not change the structure of prepared samples remarkably. Bi3+ in ZnB2O4 can emit intense broad-band purplish blue light peaking at 428 nm under the excitation of a broad-band peaking at 329 nm. The optimal doping concentration of Bi3+ is experimentally ascertained to be 0.5 mol%. The decay time of Bi3+ in ZnB2O4 changes from 0.88 to 1.69 ms. Gd3+ in ZnB2O4 can be excited with 254 nm ultraviolet light and yield intense 312 nm emission. The optimal doping concentration of Gd3+ is experimentally ascertained to be 5 mol%. The decay time of Gd3+ in ZnB2O4 changes from 0.42 to 1.36 ms. 相似文献
9.
A new l-lysine derivative featuring an anthracene unit is synthesized and characterized by elemental analysis, ESI-MS, 1H-NMR, and 13C-NMR. It can selectively bind ATP in acidic aqueous solutions, and be used as a highly selective fluorescent chemosensor for Cu2+ at neutral pH, resulting in fluorescence quenching. According to these characters, two combinational logic circuits are fabricated on a single molecule with three chemical inputs [H+(IN1), OH−(IN2), ATP (IN31)] and [H+(IN1), OH−(IN2), Cu2+(IN32)], respectively. 相似文献
10.
This paper compares two formal methods, B and eb3, for specifying information systems. These two methods are chosen as examples of the state-based paradigm and the event-based paradigm, respectively. The paper considers four viewpoints: functional behavior expression, validation, verification, and evolution. Issues in expressing event ordering constraints, data integrity constraints, and modularity are thereby considered. A simple case study is used to illustrate the comparison, namely, a library management system. Two equivalent specifications are presented using each method. The paper concludes that B and eb3 are complementary. The former is better at expressing complex ordering and static data integrity constraints, whereas the latter provides a simpler, modular, explicit representation of dynamic constraints that are closer to the user’s point of view, while providing loosely coupled definitions of data attributes. The generality of these results from the state-based paradigm and the event-based paradigm perspective are discussed. 相似文献
11.
Anthony J.T. LeeAuthor Vitae Han-Pang ChiuAuthor VitaePing YuAuthor Vitae 《Pattern recognition》2002,35(11):2521-2537
In video database systems, one of the most important methods for discriminating the videos is by using the objects and the perception of spatial and temporal relations that exist between objects in the desired videos. In this paper, we propose a new spatio-temporal knowledge representation called 3D C-string. The knowledge structure of 3D C-string, extended from the 2D C+-string, uses the projections of objects to represent spatial and temporal relations between the objects in a video. Moreover, it can keep track of the motions and size changes of the objects in a video. The string generation and video reconstruction algorithms for the 3D C-string representation of video objects are also developed. By introducing the concept of the template objects and nearest former objects, the string generated by the string generation algorithm is unique for a given video and the video reconstructed from a given 3D C-string is unique too. This approach can provide us an easy and efficient way to retrieve, visualize and manipulate video objects in video database systems. Finally, some experiments are performed to show the performance of the proposed algorithms. 相似文献
12.
《国际计算机数学杂志》2012,89(3):679-689
In this paper, quadrature formulas with remaining term in integral form for functions partially holomorphic with respect to each variable in a Jordan polydomain in C 2 and a complex double integral formula are given. For this, we used the Cauchy Integral formula for Jordan polydomain in C 2. 相似文献
13.
This article proposes a linear dynamic anti-windup strategy for the alleviation of performance and stability problems in systems which are linear apart from saturating sensors. Unlike anti-windup compensation for systems subject to actuator saturation, there is no agreed architecture for applying anti-windup to systems with sensor saturation and therefore attention is devoted to the discussion of various candidate configurations which can be interpreted as a particular choice of a static non-linear map. The main results of the article give existence conditions for compensators which yield global exponential stability and finite ?2 gain of the overall non-linear closed-loop system. The existence conditions are different to those which have appeared hitherto in the literature. 相似文献
14.
A new Mn(II) complex of MnL2Cl2 (L = azino-di(5,6-azafluorene)-κ2-NN′) was synthesized and utilized as an electrochemical indicator for the determination of hepatitis B virus (HBV) based on its interaction with MnL2Cl2. The electrochemical behavior of interaction of MnL2Cl2 with salmon sperm DNA was investigated on glassy carbon electrode (GCE). In the presence of salmon sperm DNA, the peak current of [MnL2]2+ was decreased and the peak potential was shifted positively without appearance of new peaks. The binding ratio between [MnL2]2+ and salmon sperm DNA was calculated to be 2:1 and the binding constant was 3.72 × 108 mol2 L−2. The extent of hybridization was evaluated on the basis of the difference between signals of [MnL2]2+ with probe DNA before and after hybridization with complementary sequence. Control experiments performed with non-complementary and mismatch sequence demonstrated the good selectivity of the biosensor. With this approach, a sequence of the HBV could be quantified over the range from 1.76 × 10−8 to 1.07 × 10−6 mol L−1, with a linear correlation of r = 0.9904 and a detection limit of 6.80 × 10−9 mol L−1. Additionally, the binding mechanism was preliminarily discussed. The mode of interaction between MnL2Cl2 and DNA was found to be primary intercalation binding. 相似文献
15.
In this paper, we introduce a new iterative method of a k-strictly pseudo-contractive mapping for some 0≤k<1 and prove that the sequence {xn} converges strongly to a fixed point of T, which solves a variational inequality related to the linear operator A. Our results have extended and improved the corresponding results of Y.J. Cho, S.M. Kang and X. Qin [Some results on k-strictly pseudo-contractive mappings in Hilbert spaces, Nonlinear Anal. 70 (2008) 1956–1964], and many others. 相似文献
16.
The concept of a μ-basis was introduced in the case of parametrized curves in 1998 and generalized to the case of rational ruled surfaces in 2001. The μ-basis can be used to recover the parametric equation as well as to derive the implicit equation of a rational curve or surface. Furthermore, it can be used for surface reparametrization and computation of singular points. In this paper, we generalize the notion of a μ-basis to an arbitrary rational parametric surface. We show that: (1) the μ-basis of a rational surface always exists, the geometric significance of which is that any rational surface can be expressed as the intersection of three moving planes without extraneous factors; (2) the μ-basis is in fact a basis of the moving plane module of the rational surface; and (3) the μ-basis is a basis of the corresponding moving surface ideal of the rational surface when the base points are local complete intersections. As a by-product, a new algorithm is presented for computing the implicit equation of a rational surface from the μ-basis. Examples provide evidence that the new algorithm is superior than the traditional algorithm based on direct computation of a Gröbner basis. Problems for further research are also discussed. 相似文献
17.
Nonlocal boundary value problems at resonance for a higher order nonlinear differential equation with a p-Laplacian are considered in this paper. By using a new continuation theorem, some existence results are obtained for such boundary value problems. An explicit example is also given in this paper to illustrate the main results. 相似文献