In this study, carbon nanodots (C-dots)/WO photocatalysts were prepared via a two-step hydrothermal method. The morphologies and optical properties of the as-prepared materials were investigated. Compared with the prepared WO and C-dots, the C-dots/WO possessed stronger photocatalytic capability and excellent recyclability for photocatalytic elimination of Rhodamine B. For example, the achieved first order reaction rate constant of 0.01942 min for C-dots/WO was ∼7.7 times higher than that of the prepared WO. The enhanced photocatalytic activity of C-dots/WO was attributed to the enhanced light harvesting ability and efficient spatial separation of photo-excited electron-hole pairs resulting from the synergistic effect of WO and C-dots. The high photocatalytic activity of C-dots/WO remained unchanged even after 3 cycles of use. Meanwhile, a possible mechanism of C-dots/WO for the enhanced photocatalytic activity was proposed.

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One of the critical failure modes caused by dust contamination in electronics is surface insulation resistance degradation, or impedance degradation. Impedance degradation can lead to intermittent or permanent failure of PCB assemblies. In this study, two outdoor natural dust samples were collected from the field. We experimentally demonstrated that natural dust can cause impedance degradation under controlled temperature (20°C to 60°C) and relative humidity (50% to 95%) conditions. Critical transition ranges of relative humidity for the two dust samples were determined. Below the starting point of the transition range, the impedance was constant. Above the starting point of the range, the impedance degraded by orders of magnitude. The value of the critical transition range decreased with an increase in dust deposition density. Significant impedance degradation was observed as the temperature was raised from 20°C to 50°C. For each 10°C increase of temperature, the impedance dropped by approximately one order of magnitude. The failure mechanisms behind the impedance degradation processes associated with dust are discussed. Critical relative humidity of mixed salts, percentage of deliquescent substance, deposition density, and moisture sorption capacity were found to be key factors of dust that determine the effect of dust on impedance degradation.

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The effect of different Ce content on the hot ductility of C-Mn steel containing arsenic was investigated at the temperature ranging from 700 to 1100°C conducting Gleebel-1500 thermal-mechanical simulator. The reduction of area (RA%) was used to evaluate the hot ductility. The 0.16 mass% As widened the ductility trough range and especially, decreased the RA value at 850-950°C. Conversely, adding Ce in the steel could remedy the arsenic-induced hot ductility deterioration. Moreover, with the increase of Ce content from 0 to 0.035 mass%, the RA value at 800-950°C significantly increased, compared to that of the arsenic steel. When the content of Ce reached 0.027-0.035 mass%, the RA value at 800-850°C was even higher than that of steel without As. Besides, the corresponding fracture morphology was changed from intergranular feature to ductile and/or interdendritic feature. Grain refinement by Ce addition, the formation of arsenious rare earth inclusions and grain boundary segregation of Ce were considered to improve the hot ductility of the steel containing As.Keywords: arsenic and cerium / hot ductility / austenite grain refinement / arsenious rare earth inclusions / grain boundaries *