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608 results on '"Li, Junfang"'

6. Detection of Clostridium perfringens Using Novel Methods Based on Recombinase-Aided Amplification Assay-Assisted CRISPR/Cas12a System

Author

Xiao, Xingxing, primary, Zhang, Qingxun, additional, Wu, Sihong, additional, Li, Yi, additional, Zhong, Zhenyu, additional, Guo, Qingyun, additional, Li, Junfang, additional, Meng, Qinghui, additional, Cheng, Zhibin, additional, Duan, Jianbin, additional, Wang, Xiaoqiong, additional, He, Hongxuan, additional, Bai, Jiade, additional, and Lou, Yongliang, additional

Published
2023
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12. A fully-nonlinear flow and quermassintegral inequalities in the sphere

Author

Chen, Chuanqiang, Guan, Pengfei, Li, Junfang, and Scheuer, Julian

Subjects
Mathematics - Analysis of PDEs, Mathematics - Differential Geometry
Abstract

This expository paper presents the current knowledge of particular fully nonlinear curvature flows with local forcing term, so-called locally constrained curvature flows. We focus on the spherical ambient space. The flows are designed to preserve a quermassintegral and to de-/increase the other quermassintegrals. The convergence of this flow to a round sphere would settle the full set of quermassintegral inequalities for convex domains of the sphere, but a full proof is still missing. Here we collect what is known and hope to attract wide attention to this interesting problem., Comment: 19 pages

Published
2021
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17. The catalytic characteristics of 2-methylnaphthalene acylation with AlCl3 immobilized on Hβ as Lewis acid catalyst

Author

Sun Jingjing, Jin Haibo, Mao Xuefeng, He Guangxiang, Li Junfang, Yan Zihao, Hu Fating, Ma Lei, Guo Xiaoyan, and Yang Suohe

Subjects
2-methylnaphthalene, β,β-methyl propyl naphthalene, acylation, immobilized alcl3, zeolite molecular sieve, Chemistry, QD1-999
Abstract

The heterogeneous supported Lewis acid catalyst prepared by immobilization technology has high reaction activity. It is an environment-friendly catalyst. Using Lewis acid immobilized as the catalyst, 2-methyl-6-propionyl naphthalene is synthesized by Friedel–Crafts reaction with 2-methylnaphthalene and propionic anhydride, which has a good development prospect. A variety of AlCl3 catalysts supported by H-zeolite molecular sieves are prepared using the solvent reflux method in the paper. It is found that AlCl3/Hβ has better catalytic performance. The results showed that AlCl3/Hβ catalyst is mainly composed of L acid. The acid content of B acid and the specific surface area increase, and the pore volume and pore size decreases. With the increase in AlCl3 concentration, the acid content of strong acid, medium strong acid, and weak acid increases, but the solubility of AlCl3 in CHCl3 is limited. When the concentration of AlCl3 is too high, too much AlCl3 is deposited on the surface of the molecular sieve, which is useless to its binding with Si–OH. AlCl3/Hβ’s activity is higher when the concentration of AlCl3 is 3 g·L−1, and the solvent is refluxed for 8 h and calcined at 550°C for 3 h. Under these conditions, the conversion of 2-methylnaphthalene is 85.86%, and the yield of β,β-methyl propyl naphthalene is increased to 81.19%.

Published
2023
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33. The catalytic performance of acid-modified Hβ molecular sieves for environmentally friendly acylation of 2-methylnaphthalene

Author

Sun Jingjing, Zhang Nan, Jin Haibo, Mao Xuefeng, He Guangxiang, Li Junfang, Yan Zihao, Hu Fating, Ma Lei, Guo Xiaoyan, and Yang Suohe

Subjects
2-methylnaphthalene, β,β-methyl propyl naphthalene, acylation, citric acid modification, molecular sieve, Chemistry, QD1-999
Abstract

2,6-Methylacylnaphthalene is an important organic chemical raw material, mainly used as a precursor for synthesizing polyethylene 2,6-naphthalene dicarboxylate (PEN). The heterogeneous catalyst molecular sieve catalyzes the acylation of 2-methylnaphthalene to synthesize β,β-methylacylnaphthalene, which has good activity, is green and environmentally friendly, with simple post-treatment. Different molecular sieves and reaction solvents were selected, and Hβ molecular sieves were more suitable for the acylation reaction of 2-methylnaphthalene. The reaction results were better when sulfolane was used as a solvent in this paper. The catalytic performances of citric acid-modified Hβ molecular sieve (SiO2/Al2O3 of 25) and unmodified molecular sieve were investigated and compared. The results showed that modification with low-concentration citric acid increased the amount of mediate strong acid and Bronsted acid, the specific surface area, pore volume, and pore size of Hβ zeolite. When the concentration of citric acid was 0.3 mol·L−1, the modification time was 48 h and the calcination at 550°C for 3 h had the best catalytic activity. By further optimizing the acylation process, the conversion rate of 2-methylnaphthalene increased to 88.82%, and the yield of β,β-methyl propyl naphthalene increased to 82.12%.

Published
2022
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