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Perspectives in Biological Nitrogen Fixation Research

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Journal of Integrative Plant Biology 2008年第7期50卷 786-798页

作者： qi Cheng Department of Biochemistry Redox Biology Center University of Nebraska-Lincoln Lincoln Nebraska 68588 USA

Nitrogen fixation, along with photosynthesis is the basis of all life on earth. Current understanding suggests that no plant fixes its own nitrogen. Some plants （mainly legumes） fix nitrogen via symbiotic anaerobic microorganisms （mainly rhizobia）. The nature of biological nitrogen fixation is that the dinitrogenase catalyzes the reaction-splitting triple-bond inert atmospheric nitrogen （N2） into organic ammonia molecule （NH3）. All known nitrogenases are found to be prokaryotic, multi-complex and normally oxygen liable. Not surprisingly, the engineering of autonomous nitrogen-fixing plants would be a long-term effort because it requires the assembly of a complex enzyme and provision of anaerobic conditions. However, in the light of evolving protein catalysts, the anaerobic enzyme has almost certainly been replaced in many reactions by the more efficient and irreversible aerobic version that uses O2. On the other hand, nature has shown numerous examples of evolutionary convergence where an enzyme catalyzing a highly specific, O2-requiring reaction has an oxygen-independent counterpart, able to carry out the same reaction under anoxic conditions. In this review, I attempt to take the reader on a simplified journey from conventional nitrogenase complex to a possible simplified version of a yet to be discovered light-utilizing nitrogenase.

关键词： aerobic anaerobic anoxic convergent enzyme light-independent light-utilizing nitrogen fixation nitrogenase oxic protochlorophyllide reductase.

Spatio-temporal Distributions of Tropospheric NO_2 over Oases in Taklimakan Desert, China

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Chinese Geographical Science 2015年第5期25卷 561-568页

作者： qi Yue Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Max Planck Institute for Chemistry University of Chinese Academy of Sciences

Soil biogenic NO emission is one of the most important sources of atmospheric nitrogen oxides(NOx) worldwide. However, the estimation of soil source, especially in arid areas presents large uncertainties because of the substantial lack of measurements. In this study, we selected the Ruoqiang oases on the southeastern edge of the Taklimakan Desert, China as the study area and applied Ozone Monitoring Instrument(OMI) NO2 retrievals(DOMINO v2.0, 2005–2011) to investigate the spatial distribution and seasonal variations in tropospheric NO2 vertical column density(VCD). High NO2 VCDs were observed over the oases(farmlands and natural vegetation), with the highest value obtained during summer, and lowest during winter. Pulses were observed during spring. We conducted in-situ measurements in June 2011 in Milan oasis and employed ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS) instruments to validate satellite NO2 retrievals. The findings are as follows: 1) in the study area soil biogenic NO emission is the dominant source of tropospheric NO2; 2) oases(farmlands) are hotspots of tropospheric NO2, and a higher increase in tropospheric NO2 is found in oases from winter to summer; and 3) enhancement of soil biogenic NO emission due to soil managements is predictable. Given the rapid agricultural development in the southern Uygur Autonomous Region of Xinjiang, researches on soil biogenic NO emission and increase in tropospheric NOx should be given more importance.

关键词： NO2 vertical column density ozone monitoring instrument (OMI) soil biogenic NO emission arid area agricultural management

Bidirectional Partial Generalized Synchronization in Chaotic and Hyperchaotic Systems via a New Scheme

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Communications in Theoretical Physics 2006年第6期45卷 1049-1056页

作者： WANG qi Department of Applied Mathematics Dalian University of Technology Dalian 116024 China Key Laboratory of Mathematics Mechanization the Chinese Academy of SciencesBeijing 100080 China

In this paper, a bidirectional partial generalized （lag, complete, and anticipated） synchronization of a class of continuous-time systems is defined. Then based on the active control idea, a new systematic and concrete scheme is developed to achieve bidirectional partial generalized （lag, complete, and anticipated） synchronization between two chaotic systems or between chaotic and hyperchaotic systems. With the help of symbolic-numerical computation, we choose the modified Chua system, Lorenz system, and the hyperchaotic Tamasevicius Namajunas-Cenys system to illustrate the proposed scheme. Numerical simulations are used to verify the effectiveness of the proposed scheme. It is interesting that partial chaos synchronization not only can take place between two chaotic systems, but also can take place between chaotic and hyperchaotic systems. The proposed scheme can also be extended to research bidirectional partial generalized （lag, complete, and anticipated） synchronization between other dynamical systems.

关键词： bidirectional partial generalized (lag complete and anticipated) synchronization modified Chua system Lorenz system hyperchaotic Tamasevicius-Namajunas-Cenys system numerical simulation

The Inverse Mean Curvature Flow in Rotationally Symmetric Spaces

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Chinese Annals of Mathematics,Series B 2011年第1期32卷 27-44页

作者： qi DING School of Mathematical Sciences Fudan University Shanghai 200433 China

In this paper,the motion of inverse mean curvature flow which starts from a closed star-sharped hypersurface in special rotationally symmetric spaces is *** is proved that the flow converges to a unique geodesic spher... 详细信息

关键词： Asymptotic behavior Inverse mean curvature flow Hyperbolic space

Quenching Phenomenon for a Parabolic MEMS Equation

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Chinese Annals of Mathematics,Series B 2018年第1期39卷 129-144页

作者： qi WANG College of Science University of Shanghai for Science and Technology

This paper deals with the electrostatic MEMS-device parabolic equation u_t-?u =λf(x)/(1-u)~p in a bounded domain ? of R^N,with Dirichlet boundary condition,an initial condition u0(x) ∈ [0,1) and a nonnegative profile f,where λ > 0,p > *** study is motivated by a simplified micro-electromechanical system(MEMS for short) device *** this paper,the author first gives an asymptotic behavior of the quenching time T*for the solution u to the parabolic problem with zero initial ***,the author investigates when the solution u will quench,with general λ,u0(x).Finally,a global existence in the MEMS modeling is shown.

关键词： MEMS equation Quenching time Global existence

Numerical Solutions of Fractional Boussinesq Equation

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Communications in Theoretical Physics 2007年第3期47卷 413-420页

作者： WANG qi School of Mathematical Sciences Fudan University Shanghai 200433 China Key Laboratory of Mathematics Mechanizations the Chinese Academy of Sciences Beijing 100080 China

Based upon the Adomian decomposition method, a scheme is developed to obtain numerical solutions of a fractional Boussinesq equation with initial condition, which is introduced by replacing some order time and space derivatives by fractional derivatives. The fractional derivatives are described in the Caputo sense. So the traditional Adomian decomposition method for differential equations of integer order is directly extended to derive explicit and numerical solutions of the fractional differential equations. The solutions of our model equation are calculated in the form of convergent series with easily computable components.

关键词： fractional Boussinesq equation Adomian decomposition method

Mean Spherical Approximation-Based Partitioned Density Functional Theory

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Communications in Theoretical Physics 2003年第6X期40卷 721-726页

作者： ZHOUShi-qi InstituteofModernStatisticalMechanicsandDepartmentofPackagingEngineering ZhuzhouInstituteofTechnologyZhuzhou412008China

Previous literature claims that the density functional theory for non-uniform non-hard sphere interaction potential fluid can be improved on by treating the tail part by the third order functional perturbation expansion approximation (FPEA) with the symmetrical and intuitive consideration-based simple function C0(3)(r1, r2, r3) =ζ∫ dr4a(r4 - r1)a(r4 - r2)a(r4 - r3) as the uniform third order direct correlation function (DCF) for the tail part,here kernel function a(r) = (6/πσ3)Heaviside(σ/2 - r). The present contribution concludes that for the mean spherical approximation-based second order DCF, the terms higher than second order in the FPEA of the tail part of the non-uniform first order DCF are exactly zero. The reason for the partial success of the previous a kernel function-based third order FPEA for the tail part is due to the adjustable parameter ζ and the short range of the a kernel *** over the previous theories is proposed and tested.

关键词：球形近似密度函数理论直接相关函数 FPEA 流体力学函数扰动扩张近似

A Global Investigation About Hard Core Attractive Yukawa Approximation and Adhesive Hard Sphere Approximation for Structure of Colloidal Dispersion Systems

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Communications in Theoretical Physics 2005年第3期43卷 567-576页

作者： ZHOUShi-qi InstituteofModernStatisticalMechanics ZhuzhouInstituteofTechnologyZhuzhou412008China

The accuracy of hard core attractive Yukawa (HCAY) potential and adhesivehard sphere (AH) potential in representing the structure factor of short range square well potentialand Asakura and Oosawa (AO) depletion potential is examined by comparing theoretical predictionswith the existing simulation data and the present numerical results from the non-linear optimizedrandom phase approximation closure for Ornstein—Zernike equation. For the case of square-well (SW)potential, it is shown that the structure factor of HCAY potential based on a recently proposedsemi-analytical expression for the radial distribution function can describe the structure factor ofSW potential with reduced well width λ ≤ 2 only if the reduced contact potential βε_(sw) ≤0.25, while the analytical expression for the structure factor of AH potential under Percus-Yevick(PY) approximation completely fails for the case of λ > 1.2. For the case of AO depletionpotential, the domain of validity of both HCAY potential and AH potential is complementary. With theabove analysis and considering the solid-liquid transition of the AH potential with an adhesiveparameter τ below 1.31 cannot be predicted by modified weighted density approximation, the roleplayed by the HCAY potential about the mapping manipulation should not be ignored.

关键词： colloidal dispersion structure factor

Adaptive sampling for corrugated plate digitization using a laser displacement sensor

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Science China(Technological Sciences) 2024年第5期67卷 1510-1523页

作者： WU ChengXing qi qi CHEN BaiJin YANG JiXiang DING Han State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

The surface quality of a corrugated plate directly determines the heat transfer property of the thermal power mechanical *** detection methods are impractical for real-world production,being slow and *** contrast,the point laser displacement sensor,employing the optical triangle method,emerges as a promising device for assessing parts with variable curvature and highly reflective *** its benefits,high-density sampling by an innate frequency introduces challenges such as data redundancy and a poor signal-to-noise ratio,potentially affecting the efficiency and precision of subsequent data *** address these challenges,adjustable frequency data sampling has been developed for this sensor,allowing adaptive sampling for corrugated plate *** process begins with surface digitization to extract discrete points,which are transformed into intersection curves using the B-spline fitting ***,dominant points are identified,considering multigeometric constraints for curvature and arch ***,the sampling signal is adjusted based on the distribution information of dominant *** results indicate that the proposed method effectively minimizes redundant sampling without compromising the accurate capture of essential geometric features.

关键词： corrugated plate laser displacement sensor adaptive sampling dominant point curvature arch height