Loading an electrocatalyst on poorly conducting substrate can easily lead to undervaluation of its intrinsic property. In this study, the excellent activity of MoS|NiS|MoO nanowires for hydrogen evolution is revealed. The precursor NiMoO synthesized on chemically polished Ti foil can be successfully converted to MoS|NiS|MoO catalyst via gas-phase sulfurization. Without deep polish in sulfuric acid for 2 h, the as-synthesized materials do not show competitive results. After sulfurization, the surface morphology of the precursor is transformed into rough features, and the peripheries of these electrocatalysts are coated by multilayered and misaligned MoS with a high density of active sites and conductive component NiS. Further analysis shows that defect MoO is embedded inside each nanowire, which may facilitate fast electron transfer. Such nanostructured architecture shows promising results for hydrogen evolution reaction in alkaline medium with only 91 mV overpotential for the current density of 10 mA cm and robust long-term stability during more than 20 h of tests.

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For the first time, a novel, simple and reliable method for analysis of pymetrozine residues in flue-cured tobacco leaves has been developed utilizing HPLC-UV with liquid-liquid partition cleanup. Pre-treatment with ultrasonic extraction and liquid-liquid partition procedures gave preferable baseline separation and clean chromatograms by removing water-soluble and fat-soluble components which interfere with pymetrozine in the test. The performance of the method was evaluated and validated: the detection limit (LOD) was 0.005 microg x mL(-1), the relative standard deviation (RSD) was 1.2% (n = 5), and the overall recovery was above 90% at fortification levels of 0.200, 0.500, 1.000, and 5.000 mg x kg(-1). The proposed method was successfully employed for the determination of pymetrozine residues in twelve flue-cured tobacco samples collected from different regions of China.

A novel hydrogen peroxide (H 2 O 2 ) sensor was fabricated by using a submonolayer of 3-mercaptopropionic acid (3-MPA) adsorbed on a polycrystalline gold electrode further reacted with poly(amidoamine) (PAMAM) dendrimer (generation 4.0) to obtain a film on which Prussian Blue (PB) was later coordinated to afford a mixed and stable electrocatalytic layer for H 2 O 2 reduction. On the basis of the electrochemical behaviors, atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), it is suggested that the PB molecules are located within the dendritic structure of the surface attached PAMAM dendrimers. It was found that the PB/PAMAM/3-MPA/Au modified electrode showed an excellent electrocatalytic activity for H 2 O 2 reduction. The effects of applied potential and pH of solution upon the response of the modified electrode were investigated for an optimum analytical performance. Even in the presence of dissolved oxygen, the sensor exhibited highly sensitive and rapid response to H 2 O 2 . The steady-state cathodic current responses of the modified electrode obtained at À 0.20 V (vs. SCE) in air-saturated 0.1 mol L À1 phosphate buffer solution (PBS, pH 6.50) showed a linear relationship to H 2 O 2 concentration ranging from 1.2 Â 10 À6 mol L À1 to 6.5 Â 10 À4 mol L À1 with a detection limit of 3.1 Â 10 À7 mol L À1. Performance of the electrode was evaluated with respected to possible interferences such as ascorbic acid and uric acid etc. The selectivity, stability, and reproducibility of the modified electrode were satisfactory.

Electrochemical preparation of the Prussian blue (PB)/poly (N‐acetylaniline) (PNAANI) composite film was carried out by cyclic voltammetry (CV). Its surface morphology, which was evaluated by Atom Force Microscope (AFM), revealed that PNAANI film provides lots of redox centers for PB growth so that the electrodeposition of PB showed high current densities, and the composite film is much denser than pure PB film. The surface microstructure of the composite film was also characterized by X‐ray photoelectron spectrum (XPS). Due to the existence of electrostatic interaction between the PNAANI (polycation) film and the PB (polyanion) film, the composite film cannot be considered as a simple adherent bilayer of PB film and PNAANI film. The electroactivity and stability of the PB/PNAANI composite film in acidic electrolytes containing potassium ions were comparatively higher than that of the pure PB film. The functional composite film is expected for use in the system capable of effective accumulation of charge, and for the analytical applications towards the reduction of hydrogen peroxide due to its high electrocatalytic activity. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

As an important sensor of an unmanned surface vehicle (USV), an electro-optical device is usually used to detect ships and obstacles in USV autonomous navigation and collision avoidance. However, the installation perpendicularity error of the electro-optical device greatly impacts the line-of-sight (LOS) stability control. This error is difficult to eliminate through mechanical calibration because the platform inertial navigation axis cannot be led out. This study aims to establish the model for the perpendicularity error of electro-optical devices during circumferential scanning and analyze its impact on the stability of LOS. In addition, we present a measurement technique for perpendicularity errors utilizing sea–sky line images. Through this method, we find an error function of LOS elevation angle, which is a convex function that can quickly search out high-precision perpendicularity errors step by step. Finally, we measured and compensated the perpendicularity error according to experimental data collected by the electro-optical device. The findings of this research demonstrate that the suggested approach can efficiently mitigate low-frequency disruptions and minor amplitude high-frequency vibrations of LOS in the elevation direction. As a result, it considerably enhances the precision of stability and image observation effect of electro-optical devices.