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Cysteine (Cys) plays important roles in many physiological processes of eukaryotic cells and its detection in cells is of fundamental significance. However, glutathione (GSH), homocysteine, N-acetyl-L-cysteine and other thiols greatly hamper the detection of Cys. In particular, GSH strongly interferes with the detection of cellular Cys (30–200 μM) due to its high intracellular concentration (1–10 mM). In this work, an off–on fluorescent probe (HOTA) for the detection of Cys is presented. This probe possesses both excellent sensitivity and satisfactory selectivity for cellular Cys detection: with the addition of 200 μM Cys, the fluorescence intensity of the probe (10 μM) enhanced 117-fold and the detection limit was calculated to be 13.47 μM, which is lower than the cellular Cys concentration; the probe also selectively detected 30–200 μM cysteine over 1–10 mM glutathione. Consequently, cell imaging experiments were performed with probe HOTA. Furthermore, the results of the thiol-blocking and GSH synthesis inhibiting experiments confirmed that the intracellular emission mainly originates from the interaction between Cys and HOTA.

The effect of retrogression re-aging treatment (RRA) on the corrosion behavior of 7055 Al-Zn-Mg alloy was studied in this paper. Results provided that corrosion resistance could be greatly improved by RRA. After the RRA treatment, the isolated precipitates occurred on grain boundaries (GBs) and the low angle grain boundaries (LAGBs) presented a larger fraction compared to that of single-stage peaking aging treatment. The samples after RRA treatment also show better corrosion resistance than that of single-stage peak aging treatment. In addition, of the electrochemical impedance spectroscopy (EIS) analysis showed that the impedance spectrum was consisted of semi-infinite layer diffusion impedance and stagnant Weber impedance. The semi-infinite layer diffusion impedance corresponded to a limited retention layer on the electrode surface while the Weber impedance represented a stagnant layer of corrosion products generated by the anode branches. The aluminum alloy after RRA treatment achieved higher Rf and low Cf, Cp values and its corrosion current density was ten times smaller compared to the single-stage peak aging samples with the 10% hardness losing.

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