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A glassy carbon electrode was modified with a copper(II) complex [Cu(Sal-β-Ala) (3,5-DMPz)2] (Sal = salicylaldehyde, β-Ala = β-alanine, 3,5-DMPz = 3,5-dimethylpyrazole) and single-walled carbon nanotubes (SWCNTs). The modified electrode was used to detect catechol (CT) and hydroquinone (HQ) and exhibited good electrocatalytic activities toward the oxidation of CT and HQ. The peak currents were linear with the CT and HQ concentrations over the range of 5–215 μmol·L−1 and 5–370 μmol·L−1 with corresponding detection limits of 3.5 μmol·L−1 and 1.46 μmol·L−1 (S/N = 3) respectively. Moreover, the modified electrode exhibited good sensitivity, stability and reproducibility for the determination of CT and HQ, indicating the promising applications of the modified electrode in real sample analysis.

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Nonlinear dynamic response of catenary flexible risers excited by ocean currents is the main reason for fatigue failures. In this work, a number of experiments are conducted to improve the understanding of the intrinsic relationship between the in-plane and out-of-plane responses of a catenary flexible riser subjected to a sheared current in the depth-averaged Reynold number range of 150-1880. It is found that the interaction between the in-plane and out-of-plane responses is sensitive to the reduced velocity. Four patterns are identified, including the weak coupling, the partial coupling, the strong coupling and the strong coupling+. The interaction is negligible at low reduced velocities. In contrast, when the reduced velocity is sufficiently large, the in-plane dominant frequency coincides with that of the out-of-plane response, signifying a strong coupling. As the reduced velocity increases, only a part of the riser possesses the same dominant frequency in the in-plane and out-of-plane directions, termed partial coupling. Such pipe section is shortened, and the interaction is finally attenuated at higher reduced velocities.