Study on ageing characteristics and evaluation methods of RTV silicone rubber in high humidity area.

Due to high humidity, the ageing of room temperature vulcanized silicone rubber (RTV) has been a serious problem in Southwestern China. In order to solve the problem of RTV life prediction, the aging classification method was established by analyzing the microtopography of RTV samples in this paper. Besides, the comprehensive analysis of RTV element content, partial element content ratio, and major chemical groups of RTV samples in each aging level were conducted. It is found that as the ageing level increases, the element contents of C, Si, O, Al change accordingly and the ratio of C:Si drops from 2.39 to 1.54, and absorption peaks of the chemical groups of Si-(CH3)2, Si-O-Si, Si-CH3 and C-H in CH3 decrease. This work can enrich the investigation of RTV, and may provide useful reference for performance evaluation and replacement of RTV in substations.

Verticillium Wilt of Okra Caused by Verticillium dahliae Kleb. in China.

Okra (Abelmoschus esculentus (L.) Moench) has gained more popularity as an economically significant plant for its nutritional and medicinal value, especially in China. During 2014-2016, the root disease of okra was discovered in four okra commercial fields surveyed in China. A fungul was isolated from the infected tissues, and was identified by Verticillium dahliae based on morphological characteristics. Pathogenicity test demonstrated that the fungus was pathogenic on okra, and fulfilled Koch's postulates. The analysis of three sequences revealed 99-100% identity with the reported V. dahliae strain in GenBank. Neighbor-joining analysis of the gene sequences revealed that the representative isolates were clustered with V. dahliae. To the best of our knowledge, this is the first report of Verticillium wilt of okra in China.