[Simultaneous Determination of Hydroquinone and Catechol Based on L-Histidine-Erythrosine Composite Film Modified Glassy Carbon Electrode].

By using cyclic voltammetry method, L-histidine and erythrosine was electrodeposited on the surface of glassy carbon electrode (GCE) to obtain the modified electrode (denoted as L-His-Erythrosine/GCE). The morphology of L-His-Erythrosine/GCE was characterized by scanning electron microscopy (SEM), and the electrochemical property characterization of L-His-Erythrosine/ GCE was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The electrocatalytic oxidation of hydroquinone (HQ) and catechol (CC) on the modified electrode was discussed by differential pulse voltammetry (DPV) in this study. The L-His-Erythrosine/GCE had shown an excellent electrocatalytic activity for HQ and CC. The oxidation overpotentials of HQ and CC decreased significantly and the corresponding oxidation currents increased remarkably. Due to the large separation of oxidation peak potentials (108 mV), concentrations of HQ and CC can be easily determined simultaneously. Under the optimum conditions, the oxidation peak currents for both HQ and CC increased linearly with the respective concentrations in the 1.2 x 10(-6) to 1.1 x 10(-4) mol x L(-1) concentration range, with the detection limits of 0.19 and 0.16 µmol x L(-1) (S/N = 3), respectively. Furthermore, the modified electrode exhibited good reproducibility and selectivity. The modified electrode was successfully applied to the simultaneous determination of HQ and CC in actual water samples, the recoveries got by standard addition method were in ranges of 99.9% - 100.6% (HQ) and 99.2% - 100.2% (CC).

Ultrasonic renal-stone tracking with mesh regularization.

The efficacy of Extracorporeal Shock Wave Lithotripsy (ESWL) depends greatly on the capability to focus shock waves on renal stone. To achieve automatic focusing on moving target, the target must be under tracking. A mesh-based block matching algorithm is proposed for renal stone tracking using ultrasound image sequence. Since multiple targets are tracked together, the mesh-based tracking algorithm can provide a function of contextual regularization for solving the target missing and image degradation problems in renal stone tracking. Recorded ultrasound images of kidney during ESWL treatment are modified for demonstrating the capability of this algorithm.