A Novel Colorimetric and Fluorescent “Off-On” Chemosensor for Cu2+ Based on a Rhodamine Derivative Bearing Naphthyridine Group

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.     

A New Method for Filter Design Based on Long-Period Fibre Grating

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.     

An Eavesdropping Detecting Approach Based on Mode-Mode Correlation

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.     

Fluorene Based Ferric Complex as Colorimetric and Fluorometric Probe for Highly Selective Detection of CN− and S2− Anions

Journal of Fluorescence - A series of new chemosensor molecules bearing benzothiazole-, quinoline- and phthalazine-functionalized fluorene derivatives were synthesized and their complexation...     

A Novel Series Colorimetric and Off–On Fluorescent Chemosensors for Fe3+ Based on Rhodamine B Derivative

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.     

A New Criterion for Disruption Prediction on HL-2A

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.     

A Strain Sensor Based on OTDR for Gas Trunk Pipelines

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Programming for a Vacuum Remote-control System Based on MSP430F149

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.     

A Scheme for Generating Entangled Squeezed States Based on Cavity QED

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.     

A New Sensitive and Selective Off-On Fluorescent Zn<Superscript>2+</Superscript> Chemosensor Based on 3,3′,5,5′-Tetraphenylsubstituted Dipyrromethene

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⁺.     

A Novel Colorimetric and Off–On Fluorescent Chemosensor for Cr3+ in Aqueous Solution and its Application in Live Cell Imaging

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.     

Wavelength–Ratiometric Probes for the Selective Detection of Fluoride Based on the 6-Aminoquinolinium Nucleus and Boronic Acid Moiety

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.     

A Novel Coumarin-based Fluorescent Probe with Aggregation Induced Emission for Detecting CN− and its Applications in Bioimaging

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...     

Two Highly Sensitive and Selective Colorimetric “Off-On” Rhodamine-Based Fluorescent Chemosensor for Hg(II) in Aqueous Media

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).     

A New Approach for Calculating Vacuum Susceptibility

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.     

Formation for Bass-Relief Microprofiles Based on an Analytic Formulation

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）.     

A High-Order Meshless Bhatnagar-Gross-Krook Scheme Based on Point Collocation

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.