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9. 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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13. 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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16. 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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19. Fenamates: Forgotten treasure for cancer treatment and prevention: Mechanisms of action, structural modification, and bright future.

Author

Li, Junfang, Wang, Xiaodong, Zhang, Honghua, Hu, Xiaoling, Peng, Xue, Jiang, Weifan, Zhuo, Linsheng, Peng, Yan, Zeng, Guo, and Wang, Zhen

Subjects
DRUG repositioning, ION channels, CANCER chemotherapy, ANTINEOPLASTIC agents, CANCER treatment
Abstract

Fenamates as classical nonsteroidal anti‐inflammatory agents are widely used for relieving pain. Preclinical studies and epidemiological data highlight their chemo‐preventive and chemotherapeutic potential for cancer. However, comprehensive reviews of fenamates in cancer are limited. To accelerate the repurposing of fenamates, this review summarizes the results of fenamates alone or in combination with existing chemotherapeutic agents. This paper also explores targets of fenamates in cancer therapy, including COX, AKR family, AR, gap junction, FTO, TEAD, DHODH, TAS2R14, ion channels, and DNA. Besides, this paper discusses other mechanisms, such as regulating Wnt/β‐catenin, TGF‐β, p38 MAPK, and NF‐κB pathway, and the regulation of the expressions of Sp, EGR‐1, NAG‐1, ATF‐3, ErbB2, AR, as well as the modulation of the tumor immune microenvironment. Furthermore, this paper outlined the structural modifications of fenamates, highlighting their potential as promising leads for anticancer drugs. [ABSTRACT FROM AUTHOR]

Published
2025
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25. A Bio-inspired Geomagnetic Homing Navigation Method Based on Magnetotaxis Perception

Author

Liu, Kun, Li, Junfang, Wang, Xinhui, Akan, Ozgur, Editorial Board Member, Bellavista, Paolo, Editorial Board Member, Cao, Jiannong, Editorial Board Member, Coulson, Geoffrey, Editorial Board Member, Dressler, Falko, Editorial Board Member, Ferrari, Domenico, Editorial Board Member, Gerla, Mario, Editorial Board Member, Kobayashi, Hisashi, Editorial Board Member, Palazzo, Sergio, Editorial Board Member, Sahni, Sartaj, Editorial Board Member, Shen, Xuemin (Sherman), Editorial Board Member, Stan, Mircea, Editorial Board Member, Jia, Xiaohua, Editorial Board Member, Zomaya, Albert Y., Editorial Board Member, Wang, Xianbin, editor, Wong, Kai-Kit, editor, Chen, Shanji, editor, and Liu, Mingqian, editor

Published
2021
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26. Interference Analysis of Anti Micro and Small Unmanned Aircraft Systems and Code Division Multiple Access Systems at Frequency Band 835–845 MHz

Author

Li, Junfang, Zhang, Changqing, Liu, Jie, Zhang, Yangmei, Liu, Kun, Song, Fei, Akan, Ozgur, Editorial Board Member, Bellavista, Paolo, Editorial Board Member, Cao, Jiannong, Editorial Board Member, Coulson, Geoffrey, Editorial Board Member, Dressler, Falko, Editorial Board Member, Ferrari, Domenico, Editorial Board Member, Gerla, Mario, Editorial Board Member, Kobayashi, Hisashi, Editorial Board Member, Palazzo, Sergio, Editorial Board Member, Sahni, Sartaj, Editorial Board Member, Shen, Xuemin (Sherman), Editorial Board Member, Stan, Mircea, Editorial Board Member, Jia, Xiaohua, Editorial Board Member, Zomaya, Albert Y., Editorial Board Member, Wang, Xianbin, editor, Wong, Kai-Kit, editor, Chen, Shanji, editor, and Liu, Mingqian, editor

Published
2021
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27. A volume preserving flow and the isoperimetric problem in warped product spaces

Author

Guan, Pengfei, Li, Junfang, and Wang, Mu-Tao

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

In this article, we continue the work in \cite{GL} and study a normalized hypersurface flow in the more general ambient setting of warped product spaces. This flow preserves the volume of the bounded domain enclosed by a graphical hypersurface, and monotonically decreases the hypersurface area. As an application, the isoperimetric problem in warped product spaces is solved for such domains., Comment: Final version. To appear in TAMS

Published
2016

28. An integral formula for affine connections

Author

Li, Junfang and Xia, Chao

Subjects
Mathematics - Differential Geometry
Abstract

In this article, we introduce a $2$-parameter family of affine connections and derive the Ricci curvature. We first establish an integral Bochner technique. On one hand, this technique yields a new proof to our recent work in \cite{LX} for substatic manifolds. On the other hand, this technique leads to various geometric inequalities and eigenvalue estimates under a much more general Ricci curvature conditions. The new Ricci curvature condition interpolates between static Ricci tensor and $1$-Bakry-Emery Ricci, and also includes the conformal Ricci as an intermediate case., Comment: Final version, to appear in J. Geom. Anal

Published
2016

36. An integral formula and its applications on sub-static manifolds

Author

Li, Junfang and Xia, Chao

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

In this article, we first establish the main tool - an integral formula for Riemannian manifolds with multiple boundary components (or without boundary). This formula generalizes Reilly's original formula from \cite{Re2} and the recent result from \cite{QX}. It provides a robust tool for sub-static manifolds regardless of the underlying topology. Using this formula and suitable elliptic PDEs, we prove Heintze-Karcher type inequalities for bounded domains in general sub-static manifolds which recovers some of the results from Brendle \cite{Br} as special cases. On the other hand, we prove a Minkowski inequality for static convex hypersurfaces in a sub-static warped product manifold. Moreover, we obtain an almost Schur lemma for horo-convex hypersurfaces in the hyperbolic space and convex hypersurfaces in the hemi-sphere, which can be viewed as a special Alexandrov-Fenchel inequality.

Published
2016

47. A mean curvature type flow in space forms

Author

Guan, Pengfei and Li, Junfang

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

In this article, we introduce a new type of mean curvature flow for bounded star-shaped domains in space forms and prove its longtime existence, exponential convergence without any curvature assumption. Along this flow, the enclosed volume is a constant and the surface area evolves monotonically. Moreover, for a bounded convex domain in R n+1, the quermassintegrals evolve monotonically along the flow which allows us to prove a class of Alexandrov-Fenchel inequalities of quermassintegrals.

Published
2013

49. A geometric characterization of a sharp Hardy inequality

Author

Lewis, Roger T., Li, Junfang, and Li, Yanyan

Subjects
Mathematics - Analysis of PDEs, Mathematics - Functional Analysis, Mathematics - Spectral Theory, 35R45, 35J20
Abstract

In this paper, we prove that the distance function of an open connected set in $\mathbb R^{n+1}$ with a $C^{2}$ boundary is superharmonic in the distribution sense if and only if the boundary is {\em weakly mean convex}. We then prove that Hardy inequalities with a sharp constant hold on {weakly mean convex} $C^{2}$ domains. Moreover, we show that the {weakly mean convexity} condition cannot be weakened. We also prove various improved Hardy inequalities on mean convex domains along the line of Brezis-Marcus \cite{BM}., Comment: The results were improved to $C^2$ domains

Published
2011

50. Hypersurfaces of Prescribed Curvature Measure

Author

Guan, Pengfei, Li, Junfang, and Li, YanYan

Subjects
Mathematics - Differential Geometry, Mathematics - Analysis of PDEs, 53C23, 35J60, 53C42
Abstract

We consider the corresponding Christoffel-Minkowski problem for curvature measures. The existence of star-shaped $(n-k)$-convex bodies with prescribed $k$-th curvature measures ($k>0$) has been a longstanding problem. This is settled in this paper through the establishment of a crucial $C^2$ a priori estimate for the corresponding curvature equation on $\mathbb S^n$.

Published
2011
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