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Electrochemical impedance spectroscopy is one of the important tools for the performance analysis and diagnosis of proton exchange membrane fuel cells. The equivalent circuit model is an effective method for electrochemical impedance spectroscopy resolution. In this paper, four typical equivalent circuit models are selected to comprehensively compare and analyze the difference in the fitting results of the models for the electrochemical impedance spectroscopy under different working conditions (inlet pressure, stoichiometry, and humidity) from the perspective of the fitting accuracy, change trend of the model parameters, and the goodness of fit. The results show that the fitting accuracy of the model with the Warburg element is the best for all under each working condition. When considering the goodness of fit, the model with constant phase components is the best choice for fitting electrochemical impedance spectroscopy under different inlet pressure and air stoichiometry. However, under different air humidity, the model with the Warburg element is best. This work can help to promote the development of internal state analysis, estimation, and diagnosis of the fuel cell based on the equivalent circuit modeling of electrochemical impedance spectroscopy.

Developing anode catalysts with substantially enhanced activity for hydrogen oxidation reaction (HOR) and CO tolerance performance is of great importance for the commercial applications of proton exchange membrane fuel cells (PEMFCs). Herein, an excellent CO‐tolerant catalyst (Pd‐WO3/C) has been fabricated by loading Pd nanoparticles on WO3 via an immersion‐reduction route. A remarkably high power density of 1.33 W cm−2 at 80 °C is obtained by using the optimized 3Pd‐WO3/C as the anode catalyst of PEMFCs, and the moderately reduced power density (73% remained) in CO/H2 mixed gas can quickly recover after removal of CO‐contamination from hydrogen fuel, which is not possible by using Pt/C or Pd/C as anode catalyst. The prominent HOR activity of 3Pd‐WO3/C is attributed to the optimized interfacial electron interaction, in which the activated H* adsorbed on Pd species can be effectively transferred to WO3 species through hydrogen spillover effect and then oxidized through the H species insert/output effect during the formation of HxWO3 in acid electrolyte. More importantly, a novel synergetic catalytic mechanism about excellent CO tolerance is proposed, in which Pd and WO3 respectively absorbs/activates CO and H2O, thus achieving the CO electrooxidation and re‐exposure of Pd active sites for CO‐tolerant HOR.

ObjectiveThe prevalence of food allergy (FA) has been increasing in recent years and has become an important public health, food safety, and clinical nutrition problem. However, population-based studies on the prevalence of FA are very limited in China. This study aims to determine the prevalence and pattern of parent-reported FA among school children in Jiangxi Province, China.MethodsA multicenter cross-sectional study on FA was conducted on primary school children aged 6-11 years old using random cluster sampling with a questionnaire survey. Parent-reported FA was used and defined as individual-reported FA by parent or guardian through a questionnaire in this study.ResultAmong the total of 8,856 (96.36%) complete questionnaires received, 727 (8.2%) children had adverse reactions to food (ARF). The prevalence rates of parent-reported FA and doctor-diagnosed FA were 6.2% and 3.3%, respectively. Animal-derived foods were the main causative source of FA, and the three leading allergenic foods were shrimp, mango, and mollusks. Skin reactions were the most common clinical manifestations of FA, accounting for 63.7%, and 45.32% of the subjects with parent-reported FA experienced severe allergic reactions. There was a significant difference in parent-reported FA between different survey centers, and FA risk increased significantly in children with other allergic diseases (P<0.001) and small family size (P=0.026). The FA prevalence was significantly higher among children aged 8-11 years than those aged 6-7 years (P=0.020).ConclusionsA high prevalence of parent-reported FA was observed among children in general primary schools in Jiangxi Province, China. Shrimp, mango, and mollusks were the most common causative foods. The main common symptoms of FA were adverse reactions relating to the skin system. The rate of severe allergic reactions was also high in Jiangxi Children with reported FA. Local standards and policies for the prevention and management of FA need to be adjusted on a timely basis according to actual local conditions.

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