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Antioxidative potential of metformin:Possible protective mechanism against generating OH radicals

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Frontiers of Environmental Science & Engineering 2021年第2期15卷 55-63页

作者： Huibin guo Ning Wang xiang Li College of Environmental Science and Engineering Xiamen University of TechnologyXiamen361024China Department of Environmental Science&Engineering Fudan UniversityShanghai 200032China Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Fudan UniversityShanghai 20032China Environment Research Institute Shandong UniversityQingdao 266237China

Exposure to particulate matter(PM)can lead to the excessive accumulation of reactive oxygen species(ROS),which causes oxidative stress and endangers human *** this study,the effects of metformin on PM-induced radicals were investigated,and the antioxidation reaction mechanism of metformin was analyzed by the density functional theory(DFT)*** corresponding results revealed that the consumption rate of dithiothreitol(DTT)increased as the metformin concentration(0–40 mmol/L)increased under exposure to PM active ***,the OH radical content decreased as the metformin concentration *** result may be related to the consumption of PM-induced OH radicals by metformin,which promotes the DTT consumption ***,because the initiation reaction has a high barrier,the oxidation reaction rate between metformin and·O_(2)–is not very fast,although various catalysts may be present in the human ***,we found that the barrier of metformin induced by OH radicals is only 9.6 kcal/mol while the barrier of metformin induced by oxygen is 57.9 kcal/mol,which shows that the rate of the·OH-initiated oxidative reaction of metformin is much faster and that this reaction path occurs more *** sample analysis,the mean OH radical generation was 55 nmol/min/g(ranging from 5 to 105 nmol/min/g)on haze days and 30 nmol/min/g(ranging from 10 to 50 nmol/min/g)on non-haze ***,OH radical generation was higher on haze days than on neighboring non-haze *** together,all data suggest that metformin could consume the PM-induced radicals,such as OH radicals and·O_(2)–,thereby providing health protection.

关键词： Antioxidative potential Metformin Mechanism OH radical Health protection

Modeling static friction behavior of elastic–plastic spherical adhesive microcontact in full-stick condition

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Friction 2024年第11期12卷 2594-2610页

作者： guo xiang Roman GOLTSBERG Izhak ETSION Department of Mechanical Engineering TechnionHaifa 32000Israel

The static friction behavior of an elastic–plastic spherical adhesive microcontact between a rigid flat and a deformable sphere under combined normal and tangential loading is studied by the finite element method(FEM).The contact between the sphere and the rigid flat is assumed to be full-stick,and the sliding inception is related to a loss of tangential *** intermolecular force between the rigid flat and the sphere is assessed by the Lennard–Jones(LJ)potential,which is applied to the sphere and the rigid flat by a user *** evolution of the adhesive force with tangential displacement in the full-stick condition is *** results indicate that the increasing effect of adhesive energy on the static friction coefficient gradually diminishes with an increase in the adhesive energy and the external normal ***,based on an extensive parametric study,an empirical dimensionless expression is obtained to predict the static friction coefficient of the spherical adhesive microcontact considering the intermolecular force.

关键词： adhesive spherical microcontact Lennard–Jones(LJ)potential elastic–plastic static friction

Korteweg-de Vries Description of Dark Solitons in Bose-Einstein Condensates

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Chinese Physics Letters 2001年第5期18卷 628-630页

作者： HUANG guo-xiang Key Laboratory for Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal UniversityShanghai 200062

We investigate the dynamics of pulses in a cigar-shaped Bose-Einstein condensate with repulsive atom-atom interactions without using Thomas-Fermi *** the linear level our results give the Bogoliubov excitation spectrum for sound propagation with speed c=c0/√2,where c_(0) is the speed for the case without *** develop a Korteweg-de Vries(KdV)description for dark soliton propagation in the system and show that it is the quantum pressure that contributes the dispersion necessary for the formation of the dark solitons.

关键词： Einstein soliton propagation

Highly efficient electrocatalysts derived from carbon black supported non-precious metal macrocycle catalysts for oxygen reduction reaction

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Journal of Energy Chemistry 2019年第1期28卷 73-78页

作者： Lijie Hou jianing guo Zhonghua xiang State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical Technology

For the sake of accelerating the commercial application of fuel cells, non-noble metal catalysts with high activity and high stability have been widely developed to replace platinum-based catalysts. Here, we report a simple but cost-effective synthetic strategy using iron tetra-amino phthalocyanine(FePC-NH_2)and modified carbon black(HCB) to obtain a novel oxygen reduction electrocatalyst(named as FePCNH_2/HCB-800) with Fe_2O_3 wrapped in nitrogen-doped carbon(N-carbon) as active site. The HCB as template can effectively promotes the formation of Fe_2O_3 active site in the catalysts. Compared to commercial Pt/C catalyst, the Fe PC-NH_2/HCB-800 catalyst exhibits high electrocatalytic activity for oxygen reduction reaction(ORR) with onset potential of 0.98 V and half-wave potential with 0.84 V vs. reversible hydrogen electrode(RHE). Meanwhile, the catalyst also shows excellent circulation stability. We believe that this work provides a platform for ORR and is conducive to the commercialization of fuel cells and metal-air batteries.

关键词： Oxygen reduction reaction Iron tetra-amino phthalocyanine Fuel cell Electrocatalyst

A Facile Modifier-free Approach to Fabricate Antistatic Superhydrophobic Composite Coatings with Remarkable Thermal Stability and Corrosion Resistance

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Journal of Bionic Engineering 2020年第3期17卷 421-435页

作者： xiang Liu Dekun Zhang Zhiguang guo School of Mechatronic Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China School of Materials Science and Engineering China University of Mining and TechnologyXuzhou 221116China Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials Hubei UniversityWuhan 430062China

Research on antistatic superhydrophobic surfaces has attracted widespread attention in some ***,in the application of superhydrophobic materials,fabricating stable and practical superhydrophobic surfaces through facile and low-cost approaches still faces considerable ***,a polyphenylene sulfide(PPS)-based antistatic superhydrophobic composite coating with a high water contact angle(166°)and a low sliding angle(2°)was fabricated on a Q345 steel surface through a simple spray-coating method without any ***,the as-prepared superhydrophobic coating also displayed excellent superhydrophobicity for water droplets at different pH values,as well as self-cleaning,anti-fouling and anti-icing ***,the superhydrophobic coating still exhibited superhydrophobicity after calcination at 350°C for 1 h,indicating its outstanding thermal *** antistatic and anticorrosion properties were obtained on the prepared coating surface,which allows the coating to be applied under harsh *** from the above characteristics,compared with the commercial coating,the as-obtained antistatic superhydrophobic coating may be applied more widely in related fields.

关键词： no-modifier superhydrophobicity thermal stability antistatic property anticorrosion

Efficient Processing of Distributed Twig Queries Based on Node Distribution

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Journal of Computer Science & Technology 2017年第1期32卷 78-92页

作者： Xin Bi xiang-guo Zhao guo-Ren Wang College of Computer Science and Engineering Northeastern University Shenyang 110815 China

Massive XML data are increasingly generated for the representation, storage and exchange of web information. Twig query processing over massive XML data has become a research focus. However, most traditional algorithms cannot be directly implemented in a distributed manner. Some of the existing distributed algorithms generate a lot of useless intermediate results and execute many join operations of partial results in most cases; others require the priori knowledge of query pattern before XML partition, storage and query processing, which is impractical in the cases of large-scale data or frequent incoming new queries. To improve efficiency and scalability, in this paper, we propose a 3-phase distributed algorithm DisT3 based on node distribution mechanism to avoid unnecessary intermediate results. Furthermore, we propose a lightweight local index ReP with an enhanced XML partitioning approach using arbitrary partitioning strategy, and based on ReP we propose an improved 2-phase distributed algorithm DisT2ReP to further reduce the communication cost. After the performance guarantees are analyzed, extensive experiments are conducted to verify the efficiency and scalability of our proposed algorithms in distributed twig query applications.

关键词： XML twig query distributed computing node distribution

Induction of Differentiation of Mesenchymal Stem Cells into Retinal Pigment Epithelial Cells for Retinal Regeneration by Using Ciliary Neurotrophic Factor in Diabetic Rats

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Current Medical Science 2021年第1期41卷 145-152页

作者： Qing HUANG Yi DING ji-guo YU jing LI Yi xiang Na TAO Department of Ophthalmology The Central Hospital of WuhanTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430014China

Diabetic retinopathy(DR)is a common cause of blindness all over the *** marrow mesenchymal stem cells(BMSCs)have been considered as a promising strategy for retinal regeneration in the treatment of ***,the poor viability and low levels of BMSCs engraftment limit the therapeutic potential of *** present study aimed to examine the direct induction of BMSCs differentiation into the cell types related to retinal regeneration by using soluble cytokine ciliary neurotrophic factor(CNTF).We observed remarkably increased expression of cellular retinaldehyde-binding protein(CRALBP)and retinoid isomerohydrolase(RPE65)in BMSCs treated with CNTF in vitro,indicating the directional differentiation of BMSCs into the retinal pigment epithelium(RPE)cells,which are crucial for retinal *** vivo,the diabetic rat model was established by use of streptozotocin(STZ),and animals treated with BMSCs+CNTF exhibited better viability and higher delivery efficiency of the transplanted cells than those treated with BMSCs injection *** to the in-vitro result,treatment with BMSCs and CNTF combined led to the differentiation of BMSCs into beneficial cells(RPE cells),and accelerated retinal healing characterized by the activation of rod photoreceptor cells and phagocytosis function of RPE *** conclusion,CNTF contributes to the differentiation of BMSCs into RPE cells,which may help overcome the current stem cell therapy limitations in the field of retinal regeneration.

关键词： mesenchymal stem cells differentiation ciliary neurotrophic factor retinal regeneration retinal pigment epithelium(RPE)

THE LARGE TIME CONVERGENCE OF SPECTRAL METHOD FOR GENERALIZED KURAMOTO-SIVASHINSKY EQUATIONS

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Journal of Computational Mathematics 1997年第1期15卷 1-13页

作者： guo, B xiang, XM SHANGHAI NORMAL UNIV SHANGHAIPEOPLES R CHINA INST APPL PHYS & COMPUTAT MATH BEIJINGPEOPLES R CHINA

In this paper we use the spectral method to analyse the generalized Kuramoto-Sivashinsky equations. We prove the existence and uniqueness of global smooth solution of the equations. Finally, we obtain the error estima... 详细信息

关键词： UN EH THE LARGE TIME CONVERGENCE OF SPECTRAL METHOD FOR GENERALIZED KURAMOTO-SIVASHINSKY EQUATIONS

Towards High Molecular Weight Poly(bisphenol A carbonate) with Excellent Thermal Stability and Mechanical Properties by Solid-State Polymerization

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Chinese Journal of Polymer Science 2015年第8期33卷 1176-1185页

作者： Yu-ling He Yi-lan guo Rui He Tian-xiang jin 陈枫傅强 Nan Zhou ji Shen College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan University China Bluestar Chengrand Chemical Co. Ltd.

Poly（bisphenol A carbonate）（BPA-PC） was post-polymerized by solid-state polymerization （SSP） after supercritical CO2-induced crystallization in low molecular weight particles prepolymerized via melt transesterification reaction. The effects of the crystallization conditions on melting behavior and SSP of BPA-PC were investigated with differential scanning calorimetry （DSC）, Ubbelohde viscosity method and gel permeation chromatography （GPC）. The reaction kinetics of the SSP of crystallized prepolymers was studied as a function of reaction temperatures for various reaction periods. As a result, the viscosity average molecular weight of BPA-PC particles （2 mm） increased from 1.9 × 10^4 g/mol to 2.8 × 10^4 g/mol after SSP. More importantly, the significantly enhanced thermal stability and mechanical properties of solid-state polymerized BPA-PC, compared with those of melt transesterification polymerized BPA-PC with the same molecular weight, can be ascribed to the substantial avoidance of undergoing high temperature during polymerization. Our work provides a useful method to obtain practical product of BPA-PC with high quality and high molecular weight.

关键词： Poly(bisphenol A carbonate) Solid-state polymerization Supercritical C02-induced crystallization Highmolecular weight High quality.