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146 results on '"Zhang, Zhaoxian"'

20. Pyrrolizidine Alkaloids in Tea (Camellia sinensisL.) from Weeds through Weed–Soil–Tea Transfer and Risk Assessment of Tea Intake

Author

Jiao, Weiting, Zhu, Lei, Li, Qing X., Shi, Taozhong, Zhang, Zhaoxian, Wu, Xiangwei, Yang, Tianyuan, Hua, Rimao, and Cao, Haiqun

Abstract

Pyrrolizidine alkaloids (PAs) have been detected in tea and can threaten human health. However, the specific source of PAs in tea is still unclear. Here, 88 dried tea products collected from six major tea-producing areas in Anhui Province, China, were analyzed. The detection frequency was 76%. The content of total PAs in dried tea was between 1.1 and 90.5 μg/kg, which was all below the MRL recommended by the European Union (150 μg/kg). In the Shexian tea garden, PAs in the weeds and weed rhizospheric soil around tea plants and the fresh tea leaves were analyzed. Intermedine (Im), intermedine-N-oxide (ImNO), and jacobine-N-oxide (JbNO) were transferred through the weed-to-soil-to-tea route into the fresh tea leaves; only Im and ImNO were detected in dried tea samples. Potential risk of the total PAs in the tea infusion was assessed according to the margin of exposure method, and it might be a low concern for public health.

Published
2023
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30. Channel selection of atmospheric remote sensing

Author

Yin, Qiu, Zhang, Zhaoxian, and Kuang, Dingbo

Subjects
Atmospheric temperature -- Research, Remote sensing -- Research, Astronomy, Physics
Abstract

We introduce a channel selection method for atmospheric remote-sensing problems described by a Fredholm integral equation of the first kind. Whether one set of channels (CH) is more suitable than another (CH[prime]) can be judged by whether (1) the degree of predominance (DP) value of CH is larger than that of CH[prime], i.e., if the number of channels is the same and (2) the number of channels of CH is more than that of CH[prime], if the DP values of both are acceptable. One can calculate the DP of the unknown function f(y) for a set of remote-sensing channels by [Mathematical Expression Omitted], [Mathematical Expression Omitted where [R.sub.a], [R.sub.b], [R.sub.c], and [(1 - [[R.sub.d].sup.2]).sup.1/2] of this channel set represent the influences on the ability to recover the unknown function caused by various measurement errors, the noise parameter, the relativity of the kernel functions, and the blindness of remote sensing means, respectively. Our channel selection method can be simplified to a conventional method when there are no differences in the relative measurement errors, no blind components of the unknown function and no noise parameters in the kernel function. Key words: Remote sensing, channel selection, atmosphere, aerosol, inversion method, radiative transfer, humidity, temperature.

Published
1996

39. Stereoselective bioactivity, toxicity and degradation of the chiral triazole fungicide bitertanol.

Author

Li, Lianshan, Gao, Beibei, Wen, Yong, Zhang, Zhaoxian, Chen, Rou, He, Zongzhe, Kaziem, Amir E, Shi, Haiyan, and Wang, Minghua

Subjects
CHLORELLA pyrenoidosa, MYCOSES, STEREOISOMERS, BOTRYTIS cinerea, PATHOGENIC fungi, FUNGICIDES
Abstract

BACKGROUND: The chiral pesticide bitertanol has been widely used in the prevention and treatment of fungal diseases on many crops. However, research on bitertanol at the stereoisomer level has not been reported. Here, we study the stereoselective bioactivity, toxicity, and degradation of this pesticide under laboratory and field conditions. RESULT: (1S,2R)‐Bitertanol was the most effective stereoisomer, showing 4.3–314.7 times more potent bioactivity than other stereoisomers against eight target pathogenic fungi. (1S,2R)‐Bitertanol showed 10.2 times greater inhibition of Botrytis cinerea spore germination than (1R,2S)‐bitertanol. According to the receptor‐drug docking results, the distances from the nitrogen atom in the heterocycle of (1S,2R)‐, (1R,2S)‐, (1R,2R)‐, and (1S,2S)‐bitertanol to the central Fe + atoms in the ferriporphyrin were 2.5, 3.8, 2.6, and 3.8 Å, respectively. (1S,2S)‐Bitertanol was 1.6–2.7 times more toxic than (1R,2R)‐bitertanol to Chlorella pyrenoidosa. The half‐lives of (1R,2S)‐, (1S,2R)‐, (1R,2R)‐, and (1S,2S)‐bitertanol were 3.7, 4.1, 4.1, and 4.8 d, respectively, in tomato. CONCLUSION: The stereoselective bioactivity, toxicity, and degradation for bitertanol were first studied here. (1S,2R)‐Bitertanol was a high efficiency and low toxicity stereoisomer. Moreover, the stereoselective bioactivity among all stereoisomers correlated with the binding distances and calculated energy differences between stereoisomers and the target protein. This study also provides a foundation for a systematic evaluation of bitertanol at the stereoisomer level. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Published
2020
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