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Rational design of geranylgeranyl diphosphate synthase enhances carotenoid production and improves photosynthetic efficiency in Nicotiana tabacum

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Science Bulletin 2022年第3期67卷 315-327页

作者： Chen Dong Ge Qu Jinggong Guo Fang Wei Shuwen Gao Zhoutong Sun Lifeng Jin Xuwu Sun jean-david rochaix Yuchen Miao Ran Wang Zhengzhou Tobacco Research Institute Zhengzhou 450001China Key Laboratory of Plant Stress Biology State Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng 475001China College of Biological Engineering Henan University of TechnologyZhengzhou 450001China Tianjin Institute of Industrial Biotechnology Chinese Academy of SciencesTianjin 300308China School of Agricultural Sciences Zhengzhou UniversityZhengzhou 450001China Departments of Molecular Biology and Plant Biology University of GenevaGeneva 1211Switzerland

Restricted genetic diversity can supply only a limited number of elite genes for modern plant cultivation and *** this study,we demonstrate that rational design enables the engineering of geranyl-geranyl diphosphate synthase(NtGGPPS),an enzyme of the methylerythritol phosphate pathway(MEP)in the model plant Nicotiana *** the crucial bottleneck in carotenoid biosynthesis,NtGGPPS1 interacts with phytoene synthase(NtPSY1)to channel GGPP into the production of *** of this enzyme in the ntggpps1 mutant leads to decreased carotenoid *** the aim of enhanc-ing NtGGPPS1 activity,we undertook structure-guided rational redesign of its substrate binding pocket in combination with sequence *** activity of the designed NtGGPPS1(a pentuple mutant of five sites V154A/I161L/F218Y/I209S/V233E,d-NtGGPPS1)was measured by a high-throughput colorimetric assay.d-NtGGPPS1 exhibited significantly higher conversion of IPP and each co-substrate(DMAPP~1995.5-fold,GPP~25.9-fold,and FPP~16.7-fold)for GGPP synthesis compared with wild-type ***,the transient and stable expression of d-NtGGPPS1 in the ntggpps1 mutant increased carotenoid levels in leaves,improved photosynthetic efficiency,and increased biomass relative to *** findings provide a firm basis for the engineering of GGPPS and will facilitate the development of quality and yield *** results open the door for the structure-guided rational design of elite genes in higher plants。

关键词： Rational design Carotenoid Methylerythritol phosphate pathway(MEP) Geranylgeranyl diphosphate synthase(GGPPS) Nicotiana tabacum

Loss of algal Proton Gradient Regulation 5 increases reactive oxygen species scavenging and H2 evolution

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Journal of Integrative Plant Biology 2016年第12期58卷 943-946页

作者： Mei Chen Jin Zhang Lei Zhao Jiale Xing Lianwei Peng Tingyun Kuang jean-david rochaix Fang Huang Key Laboratory of Photobiology Institute of Botanythe Chinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China Departments of Molecular Biology and Plant Biology University of GenevaSwitzerland

Summary We have identified hpm91, a Chlamydomonas mutant lacking Proton Gradient Regulation5 （PGRS） capable of producing hydrogen （H2） for 25 days with more than 3o-fold yield increase compared to wild type. Thus, hpm91 displays a higher capacity of H2 production than a previously characterized pgr5 mutant. Physiological and biochemical characterization of hpm91 reveal that the prolonged H2 production is due to enhanced stability of PSII, which correlates with increased reactive oxygen species （ROS） scavenging capacity during sulfur depriva- tion. This anti-ROS response appears to protect the photosynthetic electron transport chain from photo- oxidative damage and thereby ensures electron supply to the hydrogenase.

关键词： Chlamydomonas reinhardtii hpm91 hydrogen photoproduction oxidative stress photosystem II sulfur deprivation

Global Dynamic Molecular Profiling of Stomatal Lineage Cell Development by Single-Cell RNA Sequencing

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Molecular Plant 2020年第8期13卷 1178-1193页

作者： Zhixin Liu Yaping Zhou Jinggong Guo Jiaoai Li Zixia Tian Zhinan Zhu Jiajing Wang Rui Wu Bo Zhang Yongjian Hu Yijing Sun Yan Shangguan Weiqiang Li Tao Li Yunhe Hu Chenxi Guo jean-david rochaix Yuchen Miao Xuwu Sun State Key Laboratory of Crop Stress Adaptation and Improvement State Key Laboratory of Cotton BiologyKey Laboratory of Plant Stress BiologySchool of Life SciencesHenan University85 Minglun StreetKaifeng 475001China College of Life Sciences Shanghai Normal UniversityGuilin Road 100Shanghai200234China Departments of Molecular Biology and Plant Biology University of GenevaGeneva1211Switzerland

The regulation of stomatal lineage cell development has been extensively ***,a comprehensive characterization of this biological process based on single-cell transcriptome analysis has not yet been *** this study,we performed RNA sequencing on 12844 individual cells from the cotyledons of 5-day-old Arabidopsis *** identified 11 cell clusters corresponding mostly to cells at specific stomatal developmental stages using a series of marker *** analysis of genes with the highest variable expression among these cell clusters revealed transcriptional networks that regulate development from meristemoid mother cells to guard mother *** of the developmental dynamics of marker genes via pseudo-time analysis revealed potential interactions between these ***,our study opens the door for understanding how the identified novel marker genes participate in the regulation of stomatal lineage cell development.

关键词： molecular profiling stomatal development single-cell RNA-seq

MULTISCALE HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES

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Acta Mathematica Scientia 2011年第3期31卷 843-856页

作者： jean Louis Woukeng david Dongo Department of Mathematics and Computer Science Faculty of Science University of Dschang

We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic *** obtain an accurate homogenization *** also show that as the nonlinear term depends on the microscopic time variable,the global homogenized problem thus obtained is a system consisting of two hyperbolic *** is also shown that in spite of the presence of several time scales,the global homogenized problem is not a reiterated one.

关键词： hyperbolic multiscale nonlinear

Characterization of Particle Emissions of Turbocharged Direct Injection Gasoline Engine in Transients and Hot Start Conditions

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Journal of Thermal Science 2021年第6期30卷 2056-2070页

作者： Vincent BERTHOME david CHALET jean-François HETET Ecole Centrale de Nantes LHEEA Lab.(ECN/CNRS)Nantes 44300France

Reducing pollutant emissions,particularly soot particles emitted by internal combustion engines,is a major challenge for car *** this paper,the experimental setup is a turbocharged three-cylinders gasoline direct injection engine installed on a HORIBA dynamic test driven by a HORIBA STARS *** particle-measuring device is a Pegasor Particles Sensor that measures the current carried by previously electrically charged *** hot engine stabilized tests,with lambda parameter lower or equal to one,have very low emission levels,unlike dynamic *** a consequence,the present paper deals with experiments in transient *** diesel engine,cycle tests show that particulate emissions vary *** understand the phenomenon,a simple transient was created and reproduced a hundred times in order to obtain enough data to analyze and compare these different *** transient starts from idle to reach the speed of 2000 r/min and 60 N·m in 5 *** reach this point,it is necessary to stay in full load for about 3 *** maximum deviations of particles reaches 85%with the standard deviationσ=18%.The cylinder pressure sensor shows significant variations at the very beginning of each transient,i.e.,during the first 500 *** kind of result was observed for Worldwide harmonized Light vehicles Test Cycles(WLTC)with a maximum deviations of particles reaching 75%withσ=30%,on Real Drive Emissions Cycle(RDE)with a maximum deviations of particles reaching 45%withσ=22%and for a 300 s Mini-Cycle with a maximum deviations of particles reaching 70%withσ=17%.The Mini-cycle is made up of the five largest accelerations of the WLTP cycle.A complete analysis highlights the importance of filling the first engine *** depends on the opening speed of the throttle,the position of the crankshaft at the beginning of the transient,and the acceleration of the first ***,the NO_(x) sensor shows very slight variations between each *** a consequence,i

关键词： particles gasoline engine cycle-to-cycle variations transients oil consumption

On the relevance of analytical film thickness EHD equations for isothermal point contacts: Qualitative or quantitative predictions?

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Friction 2016年第4期4卷 369-379页

作者： jean-david WHEELER Philippe VERGNE Nicolas FILLOT david PHILIPPON Univ Lyon INSA Lyon CNRS LaMCoS-UMR5259 Villeurbanne F-69621 France

Thin film and elastohydrodynamic lubrication regimes are rather young domains of tribology and they are still facing unresolved *** they rely upon a full separation of the moving surfaces by a thin (or very thin) fluid film,the knowledge of its thickness is of paramount importance,as for instance to developing lubricated mechanisms with long lasting and efficient *** a consequence,a large collection of formulae for point contacts have been proposed in the last 40 ***,their accuracy and validity have rarely been *** purpose of this paper is to offer an evaluation of the most widespread analytical formulae and to define whether they can be used as qualitative or quantitative *** methodology is based on comparisons with a numerical model for two configurations,circular and elliptical,considering both central and minimum film thicknesses.

关键词： thin film lubrication elastohydrodynamic lubrication (EHL) film thickness prediction EHD analytical equation central film thickness minimum film thickness circular contacts elliptical contacts

Oil Strategies Benefits over Different Driving Cycles using Numerical Simulation

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Journal of Thermal Science 2017年第4期26卷 371-377页

作者： Hanna SARA david CHALET Mickael CORMERAIS jean-Francois HETET Ecole Centrale de Nantes LHEEA lab.(ECN/CNRS)NantesFrance MANN+HUMMEL France LavalFrance

95 g/kin is the allowed quantity of CO2 emission normalized to NEDC to be set in 2020. In addition, NEDC will be replaced by more severe driving cycles and will be united worldwide. To respond to those criteria, automotive industries are working on every possible field. Thermal management has been proved to be effective in reducing fuel consumption. Cold start is a primordial reason of ovcrconsumption, as the engine highest efficiency is at its optimal temperature. At cold start, the engine＇s oil is at its lowest temperature and thus its higher viscosity level. A high viscosity oil generates more friction, which is one of the most important heat losses in the engine. In th/s paper, hot oil storage is studied. Numerical simulations on GT-suite model were done. The model consists of a 4-cylinder turbocharged Diesel engine using a storage volume of 1 liter of hot oil. Ambient temperature vari- ation were taken into consideration as well as different driving cycles. Furthermore, different configurations of the thermal strategy （multifunction oil sump） were proposed and evaluated. Lubricant temperature and viscosity profiles are presented in the article as well as fuel consumption savings for different configurations, driving cycles and ambient temperatures.

关键词： Thermal management Hot oil storage Oil sump Oil viscosity Fuel consumption

Covalent functionalization/polycarboxylation of tungsten disulfide inorganic nanotubes （INTs-WS2）

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Nano Research 2015年第5期8卷 1454-1463页

作者： Daniel Raichman david A. Strawser jean-Paul Lellouche Department of Chemistry Nanomaterials Research Center Institute of Nanotechnology & Advanced Materials Bar-Ilan University Ramat-Gan 5290002 Israel

Inorganic nanotubes of tungsten disulfide （INTs-WS2） are insoluble in common solvents and practically inert, hindering their usefulness in both research and commercial applications. The covalent attachment of functional species onto the surface of INT-WS2 is a critical first step in realizing the potential that INT-WS2 offer for high-performance materials and products. Although a few attempts have been reported regarding preparing modified nanotubes, only a limited range of surface functionalities is possible with these methods. We have developed a versatile method, based on a modified, highly electrophilic acidic Vilsmeier- Haack reagent, to produce covalently bonded, polycarboxylated functional WS2 nanotubes that are dispersible in polar liquids, including water. The surface polycarboxylated shell provides a means for additional derivatization, enabling matching compatibility of derivatized nanotubes to both hydrophobic and hydrophilic materials. Nanocomposites incorporating derivatized INT-WS2 are expected to show improved properties as a result of enhanced interfacial compatibility, made possible by the large number of classes of functionalization available through the initial polycarboxylation step.

关键词： tungsten disulfide nanotubes inorganic nanotube of tungsten disulfide(INT-WS2) Vilsmeier-Haack reagents polycarboxylation inorganic nanotube functionalization

Modelling of Electrical Conductivity of a Silver Plasma at Low Temperature

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Plasma Science and Technology 2016年第8期18卷 812-820页

作者： Pascal ANDRE William BUSSIERE Alain COULBOIS jean-Louis GELET david ROCHETTE Université Clermont Auvergne LAEPT MERSEN 15 rue Jacques de Vaucanson

During the working of electrical fuses, inside the fuse element the silver ribbon first begins to melt, to vaporize and then a fuse arc appears between the two separated parts of the element. Second, the electrodes are struck and the burn-back phenomenon takes place. Usually, the silver ribbon is enclosed inside a cavity filled with silica sand. During the vaporization of the fuse element, one can consider that the volume is fixed so that the pressure increase appears to reach pressures higher than atmospheric pressure. Thus, in this paper two pressures, 1 atm and 10 atm, are considered. The electrical field inside the plasma can reach high values since the distance between the cathode surface and the anode surface varies with time. That is to say from zero cm to one cm order. So we consider various electrical fields： 102 V/m, 103 V/m, 5×103 V/m, 104 V/m at atmospheric pressure and 105 V/m at a pressure of 10 atm. This study is made in heavy species temperature range from 2,400 K to 10,000 K. To study the plasma created inside the electric fuse, we first need to determine some characteristics in order to justify some hypotheses. That is to say： are the classical approximations of the thermal plasmas physics justified？ In other words： plasma frequency, the ideality of the plasma, the Debye-Hückel approximation and the drift velocity versus thermal velocity. These characteristics and assumptions are discussed and commented on in this paper. Then, an evaluation of non-thermal equilibrium versus considered electrical fields is given. Finally, considering the high mobility of electrons, we evaluate the electrical conductivities.

关键词： electrical conductivity silver fuses non-ideal plasma Debye-Hiickelapproximation drift velocity thermal velocity thermal non-equilibrium electrical fields