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Insight into Reaction Mechanism of Sirtuins via Molecular Simulation and Density Functional Theory Study

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Chemical Research in Chinese Universities 2010年第5期26卷 833-837页

作者： ZHAO Yong-shan HOU Rui-zhe ZHANG Hong-xing zheng qing-chuan SUN Chia-chung State Key Laboratory of Theoretical and Computational Chemistry Institute of Theoretical Chemistry Norman Bethune College of Medicine Jilin University Changchun 130021 P. R. China School of Life Sciences ＆ Biopharmaceutical Sciences Shenyang Pharmaceutical University Shenyang 110016 P R. China

With density functional theory（DFT） and molecular mechanics method, the catalytic mechanism of silent information regulator（sirtuins） has been investigated. The calculations support the SN2-1ike reaction of the initial step of the catalysis, and are consistent with experiment results. We further explored the second step of the catalysis and proposed that this step took place in a concerted reaction. In addition, the side chain of Phenylalanine33 may help to shield the glycosidic bond from water and be in a position to protect the developing oxacabenium transition state from hydrolysis. Our results of the calculations support this hypothesis that the phenylalanine33 plays a critical role in the sirtuins biology function.

关键词： Sirtuin NAD^+ p53 Model Density functional theory

Synthesis and Crystal Structure of Ethyl 2,7,7-Trimethyl-4-(4'-methylphenyl)- 5-oxo-1,4,5,6,7,8-hexahydroquinoline-3- carboxylate in Aqueous Medium

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Chinese Journal of Structural Chemistry 2005年第6期24卷 696-700页

作者： SHIDa-qing MOUJie ZHUANGQi-Ya WANGXiang-shan DepartmentofChemistry XuzhouNormalUniversityXuzhou221116China／／KeyLaboratoryofBiotechnologyonMedicalPlantsofJiangsuProvinceXuzhou221116China DepartmentofChemistry XuzhouNormalUniversityXuzhou221116China

The title compound (C22H27NO3) was obtained by the reaction of 4-methylbenzal- dehyde, dimedone, ethyl acetoacetate and ammonium acetate in water in the presence of triethyl- benzylammonium chloride (TEBA). The crystal is of orthorhombic, space group Pbcn with a = 18.242(2), b = 15.651(1), c = 14.207(2) ?, V = 4056.15(64) ?3, Mr = 353.45, Z = 8, Dc = 1.158 g/cm3, μ = 0.076, λ(MoKα) = 0.71073 ? and F(000) = 1520. The final R = 0.0453 and wR = 0.0436 for 1156 observed reflections with I > 2σ(I). X-ray analysis revealed that the pyridine ring is of boat conformation and the six-member ring fused with it adopts half-chair conformation.

关键词： hexahydroquinoline crystal structure green synthesis

Active disturbance rejection control： between the formulation in time and the understanding in frequency

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Control Theory and Technology 2016年第3期14卷 250-259页

作者： qing zheng Zhiqiang GAO Department of Electrical and Computer Engineering Gannon University Erie PA 16541 U.S.A. Center for Advanced Control Technologies Department of Electrical and Computer Engineering Cleveland State University Cleveland OH 44115 U.S.A.

With the rapid deployments of the active disturbance rejection control （ADRC） as a bonafide industrial technology in the background, this paper summarizes some recent results in the analysis of linear ADRC and offers explanations in the frequency response language with which practicing engineers are familiar. Critical to this endeavor is the concept of bandwidth, which has been used in a more general sense. It is this concept that can serve as the link between the otherwise opaque state space formulation of the ADRC and the command design considerations and concerns shared by practicing engineers. The remarkable characteristics of a simple linear ADRC was first shown in the frequency domain, followed by the corresponding analysis in time domain, where the relationship between the tracking error and the ADRC bandwidth is established. It is shown that such insight is only possible by using the method of solving linear differential equations, instead of the more traditional techniques such as the Lyapunov methods, which tend to be more conservative and difficult to grasp by engineers. The insight obtained from such analysis is further demonstrated in the simulation validation.

关键词： Active disturbance rejection control extended state observer uncertain systems stability bandwidth

Large Time Behavior of Solutions to a 3D Keller-Segel-Stokes System Involving a Tensor-valued Sensitivity with Saturation

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Acta Mathematicae Applicatae Sinica 2023年第4期39卷 1032-1064页

作者： Yuan-yuan KE Jia-shan zheng School of Mathematics Renmin University of ChinaBeijing 100872China School of Mathematics and Statistics Science Yantai UniversityYantai 264005China

In this paper we deal with the initial-boundary value problem for the coupled Keller-Segel-Stokes system with rotational flux, which is corresponding to the case that the chemical is produced instead of consumed,■subject to the boundary conditions( n-n S(x, n, c) c) · ν = c · ν = 0 and u = 0, and suitably regular initial data(n0(x), c0(x), u0(x)), where ? ? R3is a bounded domain with smooth boundary ??. Here S is a chemotactic sensitivity satisfying |S(x, n, c)| ≤ CS(1 + n)-αwith some CS> 0 and α > 0. The greatest contribution of this paper is to consider the large time behavior of solutions for the system(KSS), which is still open even in the 2D case. We can prove that the corresponding solution of the system(KSS) decays to(■) exponentially, if the coefficient of chemotactic sensitivity is appropriately small. As a precondition to consider the asymptotic behavior, we also show the global existence and boundedness of the corresponding initial-boundary problem KSS with a simplified method. We find a new phenomenon that the suitably small coefficient CSof chemotactic sensitivity could benefit the global existence and boundedness of solutions to the model KSS.

关键词： Large time behavior Global existence Boundedness Keller-Segel-Stokes system

Effects of the continuous cooling process conditions on the crystallization and liberation characteristics of anosovite in Ti-bearing titanomagnetite smelting slag

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1120-1128页

作者： Zhen Wang Hao-yan Sun qing-shan Zhu State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

This study involved the investigation of the effects of the continuous cooling process conditions on the crystallization and liberation characteristics of anosovite in Ti-bearing titanomagnetite smelting slag. The samples were heated until melting and then the temperature was held at 1650℃ for nearly 0.5 h;subsequently, the samples were cooled at different cooling rates to different temperatures and water-quenched after being held for different times at these temperatures. Last, the obtained crystallized samples were used to analyze the crystallization and liberation characteristics. It was found that, during the continuous cooling process, anosovite particles were found to initially precipitate in the slag at a relatively high crystallization temperature, showing the characteristics of euhedral crystal. The precipitation and growth of anosovite grain is strong and the morphology of anosovite was basically not affected by the continuous cooling conditions. From the morphology perspective, the formed anosovite is an excellent Ti-rich phase to be selective separated. The formation of spinel and diopside is negative for the liberation and selective separation of the anosovite phase. The crystallization diagrams of TiO2-MgO-CaO-SiO2-Al2O3-FeO slag undergoing different continuous cooling processes were constructed to help to determine the optimal continuous cooling–quenching condition for selective separation of anosovite. Moreover, the addition of B2O3 can enlarge the range of the optimal continuous cooling–quenching conditions for selective separation of anosovite.

关键词： titanium-bearing slag crystallization anosovite liberation titanomagnetite

Driving mechanisms of nitrogen transport and transformation in lacustrine wetlands

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Science China Earth Sciences 2016年第3期59卷 464-476页

作者： ZHAO shan ZHOU Nian qing SHEN Xin Ping Department of Hydraulic Engineering Tongji UniversityKey Laboratory of Yangtze River Water Environment Ministry of Education Shanghai 200092 China School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta Georgia 30332 USA Dongting Lake Water Resources Administration Bureau of Hunan Province Changsha 410007 China

As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces(passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential(Eh) and p H, and microorganisms are the predominant pulling forces(active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.

关键词： Nitrogen Driving mechanisms Transport and transformation Excessive loading Lacustrine wetlands

Microporous metal-organic framework materials for efficient capture and separation of greenhouse gases

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Science China Chemistry 2023年第8期66卷 2181-2203页

作者： shan-qing Yang Tong-Liang Hu Banglin Chen School of Materials Science and Engineering National Institute for Advanced MaterialsNankai UniversityTianjin300350China Department of Chemistry University of Texas at San AntonioSan AntonioTexas78249-0698USA

The release of anthropogenic greenhouse gases into the atmosphere poses serious risks to the environment and human health,and is a global threat of growing *** order to ameliorate the greenhouse gas emission problems,the efficient capture and separation of these greenhouse gases are greatly ***-organic framework(MOF)materials,a relatively new kind of organic-inorganic hybrid porous materials with unique framework features,tunable pore environment and high surface areas,have been widely studied as regards their applicability to this *** the well-defined structures of MOF materials greatly promote the understanding of structure-property *** this review,we intend to provide a profound account of significant progress in the field of capture and separation of greenhouse gases using MOFs as adsorbents,including carbon dioxide,methane,nitrous oxide and fluorocompounds(such as perfluorocarbons,sulfur hexafluoride,hydrochlorocarbons,and hydrofluocarbons).The strategies used to realize the efficient capture and separation of greenhouse gases have been summarized,and the relationships between the frameworks,their capture and separation performances and mechanisms are ***,the existing challenges and perspectives with regard to the development of MOF materials for the capture and separation of greenhouse gases and industrial practical application are outlined to further promote this very significant and active emerging topic.

关键词： porous materials metal-organic frameworks greenhouse gases capture and separation structure-property relationship

Defect passivation of CsPbI2Br perovskites through Zn（Ⅱ） doping:toward efficient and stable solar cells

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Science China Chemistry 2019年第8期62卷 1044-1050页

作者： Jiajun Lu shan-Ci Chen qingdong zheng State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050China

Defect passivation is an important strategy to achieve perovskite solar cells(PVSCs) with enhanced power conversion efficiencies(PCEs) and improved stability because the trap states induced by defects in the interfaces and grain boundaries of perovskites are harmful to both large open circuit voltage and high photocurrent of devices. Here, zinc cations(Zn^2+) were used as a dopant to passivate defects of the CsPbI2Br perovskite leading to Zn^2+-doped CsPbI2Br film with fewer trap states, improved charge transportation, and enhanced light-harvesting ability. Thus, the best-performance PVSC based on CsPbI2 Br with the optimal Zn^2+doping shows a higher PCE of 12.16% with a larger open-circuit voltage(VOC) of 1.236 V, an improved shortcircuit current(JSC) of 15.61 mA cm^-2 in comparison with the control device based on the pure CsPbI2Br which exhibits a PCE of 10.21% with a VOCof 1.123 V, a JSCof 13.27 mA cm^-2. Time-resolved photoluminescence results show that the Zn^2+doping leads to perovskite film with extended photoluminescence lifetime which means a longer diffusion length and subsequently enhanced photocurrent and open circuit voltage. This work provides a simple strategy to boost the performance of PVSCs through Zn^2+doping.

关键词： CsPbI2Br perovskites defect passivation Zn(Ⅱ) doping all-inorganic perovskite solar cells power conversion efficiency

Adsorption behavior of Pd(Ⅱ) from aqueous solutions by D201 resin

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Rare Metals 2011年第5期30卷 470-476页

作者： XIONG Chunhua ZHU shan YAO Caiping CHEN qing Department of Applied Chemistry Zhejiang Gongshang University Hangzhou 310012 China

The adsorption and desorption behaviors of Pd（Ⅱ） on D201 resin were investigated. The effects of parameters including HCl concentrations, initial metal ion concentrations, contact time, and temperature on the adsorption of Pd（Ⅱ） were studied by batch method. The HCl concentration for studying the effects was set from 0.01 to 2 mol·L-1 and the optimal adsorption condition is in 0.01 mol·L-1 HCl solution. The adsorption isotherm of Pd（Ⅱ） on D201 resin was determined and the equilibrium data fitted the Langmuir model better than the Freundlich model. The maximum uptake capacity of Pd（Ⅱ） was 253 mg·g-1 at 298 K. The adsorption could be best described by the liquid film diffusion model. The enthalpy variation （ΔH） and entropy change （ΔS） of adsorption were equal to 2.49 kJ·mol-1 and 74.8 J·（mol·K）-1 respectively, indicating that the adsorption was endothermic in nature. Furthermore, the negative value of ΔG showed that movement of adsorbate from the solution to adsorbent surface was a spontaneous process. Pd（Ⅱ） could be eluted with 0.5 mol·L-1 HNO 3 solution. Thomas model was applied to experimental column data to determine the characteristic parameters of the column useful for process design.

关键词： adsorption palladium resins thermodynamics kinetics