Effects of the crown ether cavity on the performance of anion exchange membranes.

Anion exchange membrane fuel cells (AEMFCs) have emerged as a promising alternative to proton exchange membrane fuel cells (PEMFCs) due to their adaptability to low-cost stack components and non-noble-metals catalysts. However, the poor alkaline resistance and low OH- conductivity of anion exchange membranes (AEMs) have impeded the large-scale implementation of AEMFCs. Herein, the preparation of a new type of AEMs with crown ether macrocycles in their main chains via a one-pot superacid catalyzed reaction was reported. The study aimed to examine the influence of crown ether cavity size on the phase separation structure, ionic conductivity and alkali resistance of anion exchange membranes. Attributed to the self-assembly of crown ethers, the poly (crown ether) (PCE) AEMs with dibenzo-18-crown-6-ether (QAPCE-18-6) exhibit an obvious phase separated structure and a maximum OH- conductivity of 122.5 mS cm-1 at 80 °C (ionic exchange capacity is 1.51 meq g-1). QAPCE-18-6 shows a good alkali resistance with the OH- conductivity retention of 94.5% albeit being treated in a harsh alkali condition. Moreover, the hydrogen/oxygen single cell equipped with QAPCE-18-6 can achieve a peak power density (PPD) of 574 mW cm-2 at a current density of 1.39 A cm-2.

Incipient Fault Detection for Rolling Element Bearings under Varying Speed Conditions.

Varying speed conditions bring a huge challenge to incipient fault detection of rolling element bearings because both the change of speed and faults could lead to the amplitude fluctuation of vibration signals. Effective detection methods need to be developed to eliminate the influence of speed variation. This paper proposes an incipient fault detection method for bearings under varying speed conditions. Firstly, relative residual (RR) features are extracted, which are insensitive to the varying speed conditions and are able to reflect the degradation trend of bearings. Then, a health indicator named selected negative log-likelihood probability (SNLLP) is constructed to fuse a feature set including RR features and non-dimensional features. Finally, based on the constructed SNLLP health indicator, a novel alarm trigger mechanism is designed to detect the incipient fault. The proposed method is demonstrated using vibration signals from bearing tests and industrial wind turbines. The results verify the effectiveness of the proposed method for incipient fault detection of rolling element bearings under varying speed conditions.

Application of COI-based DNA Barcoding for Identifying Animal Medical Materials in the Chinese Pharmacopoeia / 世界科学技术-中医药现代化

Medicinal animals are important part of Traditional Chinese medicine resources in China. Cytochrome c oxidase subunit I (COI) was selected as the standard DNA barcoding sequence for animal medical materials. In this study, the 51 animal species from 45 animal medical materials in the Chinese Pharmacopoeia were selected and the intra-specific variation and the inter-specific divergence, the barcoding gap, the identification efficiency of their COI sequences were analyzed. The results showed that the inter-specific divergence is higher than intra-specific distance. The barcoding gap existed between inter-specific sequence divergence and intra-specific dis-tance. The identification efficiencies were 100% both at the genus and species level except the Arthropoda. The cluster dendrogram exhibited that different species distinguished from others. Therefore, COI sequence as a bar-code is suitable to identify the species of animal medical materials in Chinese Pharmacopoeia.