Three Characteristic Beltrami System in Even Dimensions (I): p-Harmonic Equation

Gao, Hongya,Chu, Yuming,Sun, Lanxiang Department of Mathematics 2007 Kyungpook mathematical journal Vol.47 No.3

This paper deals with space Beltrami system with three characteristic matrices in even dimensions, which can be regarded as a generalization of space Beltrami system with one and two characteristic matrices. It is transformed into a nonhomogeneous $p$-harmonic equation $d^*A(x,df^I)=d^*B(x,Df)$ by using the technique of out differential forms and exterior algebra of matrices. In the process, we only use the uniformly elliptic condition with respect to the characteristic matrices. The Lipschitz type condition, the monotonicity condition and the homogeneous condition of the operator A and the controlled growth condition of the operator B are derived.

Regularity for Very Weak Solutions of A-Harmonic Equation with Weight

Gao, Hong-Ya,Zhang, Yu,Chu, Yu-Ming Department of Mathematics 2009 Kyungpook mathematical journal Vol.49 No.2

This paper deals with very weak solutions of the A-harmonic equation $divA(x,{\nabla}u)$ = 0 (*) with the operator $A:{\Omega}{\times}R^n{\rightarrow}R^n$ satisfies some coercivity and controllable growth conditions with Muckenhoupt weight. By using the Hodge decomposition with weight, a regularity property is proved: There exists an integrable exponent $r_1=r_1({\lambda},n,p)$ < p, such that every very weak solution $u{\in}W_{loc}^{1,r}({\Omega},{\omega})$ with $r_1$ < r < p belongs to $W_{loc}^{1,p}({\Omega},{\omega})$. That is, u is a weak solution to (*) in the usual sense.

Toxoplasma gondii induces autophagy and apoptosis in human umbilical cord mesenchymal stem cells via downregulation of Mcl−1

Chu, Jia-Qi,Jing, Kai-Peng,Gao, Xiang,Li, Peng,Huang, Rui,Niu, Yan-Ru,Yan, Shou-Quan,Kong, Jun-Chao,Yu, Cai-Yuan,Shi, Ge,Fan, Yi-Ming,Lee, Young-Ha,Zhou, Yu,Quan, Juan-Hua Landes Bioscience 2017 Cell Cycle Vol.16 No.5

<P>Autophagy and apoptosis are critical for controlling Toxoplasma gondii (T. gondii) infection. T. gondii infection during pregnancy can damage the fetus and cause birth defects; however, the molecular mechanisms of this process are poorly understood. This study aims to determine the activities of autophagy and apoptosis as well as their regulatory mechanisms during T. gondii infection by using human umbilical cord mesenchymal stem cells (hUC-MSCs) as a model of congenital diseases. LC3B, a hallmark protein of autophagy was incrementally upregulated with the infection duration, whereas p62 was downregulated in T. gondii-infected hUC-MSCs. Concurrent to this result, the invasion of T. gondii into hUC-MSCs increased in a time-dependent manner. The expression levels of Bcl-2 family proteins including Bcl-2, Bcl-xL, Bim, Bax, Bid and Bak were not altered; however, Mcl-1 levels in hUC-MSCs were dramatically decreased upon T. gondii infection. In addition, at 24h post-infection, cleaved PARP and cleaved caspase-3 protein levels were elevated in hUC-MSCs. Importantly, Mcl-1 overexpression reduced the levels of autophagy- and apoptosis-related proteins in T. gondii-infected hUC-MSCs. Mcl-1 proteins were primarily expressed in the fraction containing mitochondria and strongly interacted with Beclin-1 under normal conditions; however, these interactions were remarkably attenuated by T. gondii infection. These results suggest that mitochondrial Mcl-1 is an essential signaling mediator regulating the activation of autophagy and apoptosis during T. gondii infection.</P>

Synthesis and adsorption properties of H4Ti5O12@CNT ion sieves

Gao Yuyu,Chen Jin,Chu Suihong,Yang Bo,Zheng Lu,Liu Min 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.11

In this study, H4Ti5O12@CNT ion sieves with an encapsulated structure were fabricated by combining pretreated carbon nanotubes (CNTs) as a template and carbon source, C16H36O4Ti as a titanium source, and CH3COOLi as a lithium source. By characterizing and analyzing the pretreated and untreated CNTs, numerous COOH and OH functional groups were introduced into the pretreated CNTs, which improved their dispersion in aqueous solutions and ethanol and facilitated the adsorption of lithium ions. The ion sieves prepared with the precursor roasted at 700 °C showed the best adsorption performance. Moreover, the structural integrity of the ion sieves was not affected by acid washing. For the first adsorption cycle, the ion sieves had a lithium-ion saturated adsorption capacity of 32.32 mg/g. After five adsorption–desorption cycles, the adsorption capacity only decreased by 5.1% to 30.68 mg/g, which shows that they had good cycling stability.

FRICTION CHARACTERISTICS OF A PAPER-BASED FRICTION MATERIAL

Gao, H.,Barber, G.-C.,Chu, H. The Korean Society of Automotive Engineers 2002 International journal of automotive technology Vol.3 No.4

A bench test set-up is employed to simulate the friction characteristics of a paper-based friction material operating against a steel plate. Dry friction tests are run as well as tests with transmission fluids. Glazed friction material produces a negative coefficient of friction versus sliding velocity (f-v) curve for both dry friction and lubrication with transmission fluids. At low sliding speeds, the coefficient of friction when operating in transmission fluids for glazed friction materials is greater than that under dry friction. An appreciable negative f-v slope occurs at low sliding speeds for glazed friction materials when running with the transmission fluid. The friction material after running in produces a constant f-v curve under dry friction and a negative slope when lubricated with transmission fluid. At low sliding speeds, the coefficient of friction of the run-in friction material is lower than that of the glazed wet material. On the other hand, the run-in friction material has a larger friction coefficient than does the glazed friction material at higher sliding speeds.

New Two-Weight Imbedding Inequalities for A-Harmonic Tensors

GAO, HONGYA,CHEN, YANMIN,CHU, YUMING 대한수학회 2007 Kyungpook mathematical journal Vol.47 No.1

In this paper, we first define a new kind of two-weight-A_(r)^(λ_(3))(λ_(1), λ_(2), Ω)-weight, and then prove the imbedding inequalities for A-harmonic tensors. These results can be used to study the weighted norms of the homotopy operator T from the Banach space L^(P)(D, ∧^(l)) to the Sobolev space W^(1, p)(D, ∧^(l-l), l= 1, 2, · · , n, and to establish the basic weighted L^(P)-estimates for A-harmonic tensors.

Degenerate Weakly (k₁, k₂)-Quasiregular Mappings

Gao, Hongya,Tian, Dazeng,Sun, Lanxiang,Chu, Yuming Department of Mathematics 2011 Kyungpook mathematical journal Vol.51 No.1

In this paper, we first give the definition of degenerate weakly ($k_1$, $k_2$-quasiregular mappings by using the technique of exterior power and exterior differential forms, and then, by using Hodge decomposition and Reverse H$\"{o}$lder inequality, we obtain the higher integrability result: for any $q_1$ satisfying 0 < $k_1({n \atop l})^{3/2}n^{l/2}\;{\times}\;2^{n+1}l\;{\times}\;100^{n^2}\;\[2^l(2^{n+3l}+1)\]\;(l-q_1)$ < 1 there exists an integrable exponent $p_1$ = $p_1$(n, l, $k_1$, $k_2$) > l, such that every degenerate weakly ($k_1$, $k_2$)-quasiregular mapping f ${\in}$ $W_{loc}^{1,q_1}$ (${\Omega}$, $R^n$) belongs to $W_{loc}^{1,p_1}$ (${\Omega}$, $R^m$), that is, f is a degenerate ($k_1$, $k_2$)-quasiregular mapping in the usual sense.

$\bar{WT}$-Classes of Differential Forms on Riemannian Manifolds

Hongya, Gao,Zhihua, Gu,Yuming, Chu Department of Mathematics 2008 Kyungpook mathematical journal Vol.48 No.1

The purpose of this paper is to study the relations between quasilinear elliptic equations on Riemannian manifolds and differential forms. Two classes of differential forms are introduced and it is shown that some differential expressions are connected in a natural way to quasilinear elliptic equations.

Involvement of Estrogen Receptor-α in the Activation of Nrf2-Antioxidative Signaling Pathways by Silibinin in Pancreatic β-Cells

( Chun Chu ),( Xiang Gao ),( Xiang Li ),( Xiaoying Zhang ),( Ruixin Ma ),( Ying Jia ),( Dahong Li ),( Dongkai Wang ),( Fanxing Xu ) 한국응용약물학회 2020 Biomolecules & Therapeutics(구 응용약물학회지) Vol.28 No.2

Silibinin exhibits antidiabetic potential by preserving the mass and function of pancreatic β-cells through up-regulation of estrogen receptor-α (ERα) expression. However, the underlying protective mechanism of silibinin in pancreatic β-cells is still unclear. In the current study, we sought to determine whether ERα acts as the target of silibinin for the modulation of antioxidative response in pancreatic β-cells under high glucose and high fat conditions. Our in vivo study revealed that a 4-week oral administration of silibinin (100 mg/kg/day) decreased fasting blood glucose with a concurrent increase in levels of serum insulin in high-fat diet/streptozotocin- induced type 2 diabetic rats. Moreover, expression of ERα, NF-E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in pancreatic β-cells in pancreatic islets was increased by silibinin treatment. Accordingly, silibinin (10 μM) elevated viability, insulin biosynthesis, and insulin secretion of high glucose/palmitate-treated INS-1 cells accompanied by increased expression of ERα, Nrf2, and HO-1 as well as decreased reactive oxygen species production in vitro. Treatment using an ERα antagonist (MPP) in INS-1 cells or silencing ERα expression in INS-1 and NIT-1 cells with siRNA abolished the protective effects of silibinin. Our study suggests that silibinin activates the Nrf2-antioxidative pathways in pancreatic β-cells through regulation of ERα expression.

FRICTION CHARACTERISTICS OF A PAPER-BASED FRICTION MATERIAL

H. GAO,G. C. BARBER,H. CHU 한국자동차공학회 2002 International journal of automotive technology Vol.3 No.4

A bench test set-up is employed to simulate the friction characteristics of a paper-based friction material operating against a steel plate. Dry friction tests are well as well as tests with transmission fluids. Glazed friction material produces a negative coefficient of friction versus sliding velocity (f-ν) curve for both dry friction and lubrication with transmission fluids. At low sliding speeds, the coefficient of friction when operating in transmission fluids for glazed friction materials is greater than that under dry friction. An appreciable negative f-ν slope occurs at low sliding speeds for glazed friction materials when running with the transmission fluid. The friction material after running in produces a constant f-ν curve under dry friction and a negative slope when lubricated with transmission fluid. At low sliding speeds, the coefficient of friction of the run-in friction material is lower than that of the glazed wet material. On the other hand, the run-in friction material has a larger friction coefficient than does the glazed friction material at higher sliding speeds.<br/>