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Huiqiang Wu,Xiangmin Wang,Yang Liu,Yu Zhao,Xinyue Wang,Woo-Kyoung Lee,심영기,Il Yoon,Xinming Xu,Jiazhu Li 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.5
In this article, we report the stereoselective Horner?Wadsworth?Emmons reaction of reactive carbonyl-substituted chlorophyll a derivatives with diethyl cyanomethylphosphonate. We found that the formyl or keto group at the chlorin periphery can react stereoselectively with phosphonate carbanions to produce a series of cyanomethylene-substituted chlorins with predominantly E geometry. Considering that no consistent records are available in the literature on the results of the allomerization of methyl pyropheophorbide a, we propose a reliable process for the transformation of this chlorophyll derivative. Our methodology represents a simple and efficient way for the preparation of novel, differently functionalized long-wavelength absorbing chlorins, those can be applied for photodynamic therapy, solar cells, and other relevant purposes.
Temperature characteristics of indentation rolling resistance of belt conveyor
Lidong Zhou,Zengfa Wu,Yongchao Li,Huiqiang Yao,Yuan Liu,Yuan Yuan,Wenjun Meng,Liangliang Han,Xueqin Cao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8
In order to study the influence of temperature on the indentation rolling resistance of belt conveyor, theoretical analysis, numerical simulation analysis and experimental study of conveyor belt indentation rolling resistance with temperature characteristics were carried out in this paper, and the influence rules of different factors on the indentation rolling resistance of belt conveyor were obtained. First, the three-component Maxwell model is chosen as the viscoelastic model for the conveyor belt rubber material, and the viscoelastic modulus function based on temperature effects is constructed from the DMA experimental data fitting. Second, we introduce the one-dimensional Winkler foundation model to derive a mathematical expression for the indentation rolling resistance based on temperature properties. Then, a mathematical model of the indentation rolling resistance of a conveyor belt with temperature characteristics is developed in MATLAB and numerical simulations are performed. Finally, using the existing experimental equipment to conduct experiments, the experimental results are compared with the numerical simulation result. The results show that the theoretical numerical simulation results of the indentation rolling resistance with temperature effect presented in this paper have a consistent change trend with the experimental results; at constant temperature and constant load, the indentation rolling resistance increases with increasing band velocity; at constant temperature and constant velocity, the indentation rolling resistance increases with increasing load; at constant load and speed, when the temperature is lower than 0 °C or higher than 25 °C, the rolling resistance increases with the increase of temperature, when the temperature is between 0 °C and 25 °C, the rolling resistance decreases gradually with the increase of temperature.