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Selective monitoring and targeted identification of various noxious ions have received significant attention in biology, industry and environments. Herein, we developed an easily available colorimetric and fluorescence sensor (PZ) based on phenazine derivative, successfully achieving the discriminative detection of Hg2+ and CN− ions. Compared with other interfering ions, PZ had high sensitivity and specificity towards Hg2+ and CN−. The lowest limits of Hg2+ and CN- by PZ were 1.52 × 10−8 M and 7.05 × 10−7 M, respectively. Significantly, this chemosensor PZ allowed visual monitoring of toxic Hg2+ and CN− ions in a few seconds, presenting a great potential in the practical application (skin-whitening cosmetic, water samples, and nutlet). Such an effective strategy is expected to offer some guidance for distinguishing the identification of toxic ions in optical sensing. [ABSTRACT FROM AUTHOR]

A simple and unique dual-channel chemical probe (DH) was designed and synthesized, which not only realized sequential recognition of Cu2+ and CN− by colorimetric and fluorometric methods, but also realized fluorescence detection of CN−. When different cations (Co2+, Mg2+, Ni2+, Cd2+, Hg2+, Al3+, Ag+, Cu2+, Pb2+, Fe3+, Zn2+ and Ca2+) were added into the solution containing the probe molecule DH, only Cu2+ induced an observable change in the UV-vis and fluorescence spectra, indicating that the probe molecule can be applied for specific recognition of Cu2+. The anti-interference experiment of DH to Cu2+ showed that DH has good selectivity for detecting Cu2+, with a detection limit of 7.05 × 10−7 M. In particular, the fluorescence "ON–OFF–ON" process can be recycled by sequentially adding Cu2+ and EDTA, and the fluorescence intensity remained unchanged after ten times. This observation suggested that DH can achieve reversible highly sensitive response to Cu2+ and EDTA, and can be used as a hypersensitive logic gate for Cu2+ detection. More interestingly, when different anions (CH3COO−, SO32−, H2PO4−, ClO4−, NO3−, HSO4−, I−, Cl−, F−, Br−, N3− and CN−) were added into the solution containing DH and Cu2+, only CN− induced color change of the solution from red to yellowish green, and the fluorescence intensity greatly enhanced, indicating that DH-Cu2+ has a specific response to CN−. The anti-interference experiment showed that DH-Cu2+ has good selectivity for CN−, with a detection limit of 8.11 × 10−6 M. Moreover, the probe molecule DH can detect CN−, with a detection limit of 7.61 × 10−6 M. Experimental and theoretical methods were applied to deeply study the detection mechanism of DH, present great potential in practical application for ion test strips and HeLa cell imaging reagents. [ABSTRACT FROM AUTHOR]

A catechol-functionalized phenazine imidazole (PD) was tailored with 2,3-diaminophenazine and 3,4-dihydroxy benzaldehyde, and it served as a hybrid acceptor for capturing HSO4− anions. The selectivity and sensitivity of the PD receptor for anion sensing were studied. It was found that the PD receptor could not only display a preferable sensitivity to HSO4− ions with a "turn–off" fluorescence response, but also have a strong anti-interference ability toward other common anions, especially basic anions such as CH3COO−, HPO42−, and H2PO4−. The anion recognition mechanism of PD towards HSO4− is based on multiple hydrogen bond interactions. Finally, the strips for anion detection were prepared, which were verified to be a convenient and high-efficiency test kit for detecting HSO4− ions with the naked eye. [ABSTRACT FROM AUTHOR]

A mathematical model of thermal reversal oxidation of the low concentration methane was established in this paper. The computational fluid dynamics method was used to simulate the temperature distribution and methane concentration distribution under various operating parameters. The calculated values of methane conversion showed good agreement with the corresponding available experimental data. The model was used to investigate the effects of operational conditions such as the approach velocity and equivalence ratio on the oxidation of methane. The results show that the temperature distribution within the bed is substantially M-typed;the high temperature zone and the methane concentration distribution curve along the direction of gas flow move periodically; the greater the inlet methane concentration, the higher the temperature peak, the closer to the inlet end of the temperature curve and the wider the high-temperature region; if the premixed methane gas flow rate increases from 0. 15 m/s to 0. 70 m/s,the maximum temperature peak and the high temperature zone change little, because as the gas flow velocity increases, both the heat releasing in the reaction bed and the heat carried out by the flow increase. [ABSTRACT FROM AUTHOR]

Composite porous scaffolds have attracted extensive attention in the biomedical material field. The aim of this research was to prepare a novel tri-component composite porous scaffold and to evaluate its relevant properties. The porous scaffold was composed of chitosan (CS), silk fibroin (SF), and nanohydroxyapatite particles (nHA), which we named CS/SF/nHA scaffold and prepared via salt fractionation method combined with lyophilization. The porous structure was achieved using a porogen (salt), and the pore size was controlled by the size of porogen. To evaluate the characteristics of the tri-component scaffold, three bi-component scaffolds, CS/SF, CS/nHA, and SF/nHA, were simultaneously prepared for comparison. The scaffolds were subjected to morphological, micro-structural, and biodegradation analyses. Results demonstrated that all of the scaffolds had pore sizes of 100-300 μm and a porosity of 90.5-96.1%. The biodegradation characteristics of all scaffolds meet the requirements of good biomedical materials. The investigation of the mechanical properties showed that the tri-component scaffold has better properties than the bi-component scaffolds. The in vitro biocompatibility with osteoblast-like MG-63 cells showed that all the scaffolds are suitable for cell attachment and proliferation; however, the CS/SF/nHA composite porous scaffold is much more effective than the others., (© 2013 Wiley Periodicals, Inc.)