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Contribution of Cyclic and Pseudo-cyclic Electron Transport to the Formation of Proton Motive Force in Chloroplasts

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Molecular Plant 2017年第1期10卷 20-29页

作者： Toshiharu Shikanai Hiroshi yamamoto Department of Botany Graduate School of Science Kyoto University Oiwake-cho Kitashirakawa Sakyo-ku Kyoto 606-8502 Japan CREST Japan Science and Technology Agency Chiyoda-ku Tokyo 102-0076 Japan

Photosynthetic electron transport is coupled to proton translocation across the thylakoid membrane, re- sulting in the formation of a trans-thylakoid proton gradient （△pH） and membrane potential （△ψ）. Ion trans-porters and channels localized to the thylakoid membrane regulate the contribution of each component to the proton motive force （pmf）. Although both △pH and △ψ contribute to ATP synthesis as pmf, only ~pH downregulates photosynthetic electron transport via the acidification of the thylakoid lumen by inducing thermal dissipation of excessive absorbed light energy from photosystem II antennae and slowing down of the electron transport through the cytochrome bsf complex. To optimize the tradeoff between efficient light energy utilization and protection of both photosystems against photodamage, plants have to regulate the pmf amplitude and its components, △pH and △ψ. Cyclic electron transport around photosystem I （PSI） is a major regulator of the pmf amplitude by generating pmf independently of the net production of NADPH by linear electron transport. Chloroplast ATP synthase relaxes pmf for ATP synthesis, and its activity should be finely tuned for maintaining the size of the pmf during steady-state photosynthesis. Pseudo-cyclic electron transport mediated by flavodiiron protein （FIv） forms a large electron sink, which is essential for PSI photoprotection in fluctuating light in cyanobacteria. FIv is conserved from cyanobacteria to gymno- sperms but not in angiosperms. The Arabidopsis proton gradient regulation 50（pgr5） mutant is defective in the main pathway of PSI cyclic electron transport. By introducing Physcomitrella patens genes encoding Flvs, the function of PSI cyclic electron transport was substituted by that of FIv-dependent pseudo-cyclic electron transport. In transgenic plants, the size of the pmf was complemented to the wild-type level but the contribution of △pH to the total pmf was lower than that in the wild type. In the pgr5 mutant, the size of

关键词： alternative electron transport cyclic electron transport around photosystem I ion channel flavodiironprotein proton motive force pseudo-cyclic electron transport

Numerical Simulation of Tip Leakage Vortex Effect on Hydrogen-Combustion Flow around 3D Turbine Blade

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Journal of Thermal Science 2008年第2期17卷 186-192页

作者： Naoto Miyama Kazuaki Inaba Makoto yamamoto Department of Mechanical Engineering Tokyo University of Science Graduate Aeronautical Laboratories California Institute of Technology

In these years, a lot of environmental problems such as air pollution and exhaustion of fossil fuels have been discussed intensively. In our laboratory, a hydrogen-fueled propulsion system has been researched as an alternative to conventional systems. A hydrogen-fueled propulsion system is expected to have higher power, lighter weight and lower emissions. However, for the practical use, there exist many problems that must be overcome. Considering these backgrounds, jet engines with hydrogen-fueled combustion within a turbine blade passage have been studied. Although some studies have been made on injecting and burning hydrogen fuel from a stator surface, little is known about the interaction between a tip leakage vortex near the suction side of a rotor tip and hydrogen-fueled combustion. The purpose of this study is to clarify the influence of the tip leakage vortex on the characteristics of the 3-dimensional flow field with hydrogen-fueled combustion within a turbine blade passage. Reynolds-averaged compressible Navier-Stokes equations are solved with incorporating a k-ε turbulence and a reduced chemical mechanism models. Using the computational results, the 3-dimensional turbulent flow field with chemical reactions is numerically visualized, and the three-dimensional turbulent flow fields with hydrogen combustion and the structure of the tip leakage vortex are investigated.

关键词： numerical simulation CFD gas turbine hydrogen combustion tip leakage vortex

Numerical Investigation on Super-cooled Large Droplet Icing of Fan Rotor Blade in Jet Engine

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Journal of Thermal Science 2014年第5期23卷 432-437页

作者： Keisuke Isobe Masaya Suzuki Makoto yamamoto Graduate School of Mechanical Engineering Tokyo University of Science6-3-1 NiijukuKatsushika-kuTokyo125-8585Japan Aviation Program Group Japan Aerospace Exploration Agency(JAXA)7-44-1 Jindaiji Higashi-machiChofu-shiTokyo182-8522Japan Department of Mechanical Engineering Tokyo University of Science6-3-1 NiijukuKatsushika-kuTokyo125-8585Japan

Icing(or ice accretion) is a phenomenon in which super-cooled water droplets impinge and accrete on a *** is well known that ice accretion on blades and vanes leads to performance degradation and has caused severe *** various anti-icing and deicing systems have been developed,such accidents still ***,it is important to clarify the phenomenon of ice accretion on an aircraft and in a jet ***,flight tests for ice accretion are very expensive,and in the wind tunnel it is difficult to reproduce all climate conditions where ice accretion can ***,it is expected that computational fluid dynamics(CFD),which can estimate ice accretion in various climate conditions,will be a useful way to predict and understand the ice accretion *** the other hand,although the icing caused by super-cooled large droplets(SLD) is very dangerous,the numerical method has not been established *** is why SLD icing is characterized by splash and bounce phenomena of droplets and they are very complex in *** the present study,we develop an ice accretion code considering the splash and bounce phenomena to predict SLD icing,and the code is applied to a fan rotor *** numerical results with and without the SLD icing model are *** this study,the influence of the SLD icing model is numerically clarified.

关键词： Ice Accretion Fan Rotor Blade Super-cooled Large Droplet Multi-physics Simulation

3D Computation of Hydrogen-Fueled Combustion around Turbine Blade-Effect of Arrangement of Injector Holes

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Journal of Thermal Science 2006年第3期15卷 233-239页

作者： Makoto yamamoto Junichi IKEDA Kazuaki INABA Department of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-kuTokyo162-8601Japan Graduate School of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-kuTokyo162-8601Japan

Recently, a number of environmental problems caused from fossil fuel combustion have been focused on. In addition, with the eventual depletion of fossil energy resources, hydrogen gas is expected to be an alternative energy resource in the near future. It is characterized by high energy per unit weight, high reaction rate, wide range of flammability and the low emission property. On the other hand, many researches have been underway in several countries to improve a propulsion system for an advanced aircraft. The system is required to have higher power, lighter weight and lower emissions than existing ones. In such a future propulsion system, hydrogen gas would be one of the promising fuels for realizing the requirements. Considering these backgrounds, our group has proposed a new cycle concept for hydrogen-fueled aircraft propulsion system. In the present study, we perform 3 dimensional computations of turbulent flow fields with hydrogen-fueled combustion around a turbine blade. The main objective is to clarify the influence of arrangement of hydrogen injector holes. Changing the chordwise and spanwise spacings of the holes, the 3 dimensional nature of the flow and thermal fields is numerically studied.

关键词： computational fluid dynamics turbine blade hydrogen combustion injector hole arrangement

Numerical Simulation of Sand Erosion Phenomena in Rotor/Stator Interaction of Compressor

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Journal of Thermal Science 2008年第2期17卷 125-133页

作者： Masaya Suzuki Kazuaki Inaba Makoto yamamoto Department of Mechanical Engineering Tokyo University of Science

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with each other. On the other hand, aircraft engines operating in a particulate environment are subjected to the performance and lifetime deterioration due to sand erosion. Especially, the compressor of the aircraft engines is severely damaged. The flow fields of the compressor have strongly three dimensional and unsteady natures. In order to estimate the deterioration due to sand erosion, the sand erosion simulation for a compressor is required under the consideration of the rotor-stator interaction. In the present study, we apply our three dimensional sand erosion prediction code to a single stage axial flow compressor. We numerically investigate the change of the flow field, the particle trajectories, and the eroded wall shape in the compressor, to clarify the effects of sand erosion in the compressor.

关键词： sand erosion axial compressor rotor/stator interaction computational fluid dynamics

QUADRANT ANALYSIS OF BUBBLE INDUCED VELOCITY FLUCTUATIONS IN A TRANSITIONAL BOUNDARY LAYER

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Journal of Hydrodynamics 2009年第1期21卷 93-99页

作者： HUANG Jian MURAI Yuichi yamamoto Fujio Graduate School of Engineering Fiber Amenity Engineering Course University of Fukui Bunkyo 3-9-1 Fukui 910-8507 Japan Division of Energy and Environment System School of Engineering Hokkaido University Sapporo Japan Graduate School of Engineering University of Fukui Bunkyo 3-9-1 Fukui 910-8507 Japan

Our previous study showed that the frictional drag decreases with increasing void fraction at Re〉1300, while it increases at Re 〈 1000. Decomposition of the Reynolds shear stress also implied that bubbles induce isotropy of turbulence. In order to confirm our previous analysis and to further investigate flow fields in the vicinity of bubbles, we analyze velocity fluctuations on the quadrant space in the streamwise and transverse directions （u′-v′ plane）. Here, we focus on two specific Reynolds numbers （at Re≈900 and ≈1410, which are close to the laminar-to-turbulent transition regime） and discuss bubble effects on sweep （u′〉 0, v′〈 0 ） and ejection （u′〈 0, v′〉 0） events as a function of the Reynolds number. We also illustrate velocity fluctuations in the vicinity of an individual bubble and a swarm of bubbles on the u′- v′ coordinates. The results show that a bubble swarm suppresses the velocity fluctuations at Re≈1410.

关键词： bubbly channel flow Particle Tracking Velocimetry (PTV) quadrant analysis velocity fluctuation boundary layer,laminar-to-turbulent transition

Performance of a Thermal Bipedal Walker on Inclined Surfaces with Different Leg CoMs

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Journal of Bionic Engineering 2019年第3期16卷 540-549页

作者： Lingchao Su Takeru Nemoto Akio yamamoto Department of Precision Engineering School of Engineering The University of Tokyo Japan

This paper investigates the walking performance of a thermal walker on various inclined surfaces. The thermal walker can walk only by ground heat energy using bimetal sheets. The walking performance on slopes is analyzed using a simplified walker model. The analytical result is compared with the two sets of walking experiments, on slopes with either pitch or roll inclinations. The analyses and the experiments are done with different Center-of-Mass (CoM) positions of the legs, which considerably influence the walking performance. It was found that, on up/down slopes, the stride of the thermal walker changes almost linearly with the slope angle. When the CoM was close to the center of the walker body, the walker walked backward on upward slopes. With CoM largely shifted backward, the walker could walk up slopes but did not walk down slopes well. On the other hand, when walking along a contour line of a slope, the stride decreased as the slope angle increased. The smaller leg swing distances would be caused by the change of leg swing time on such slopes.

关键词： bipedal walker bimetal thermal walker thermal actuator slope

Thermal Conductivity and Tensile Properties of Carbon Nanofiber-Reinforced Aluminum-Matrix Composites Fabricated via Powder Metallurgy: Effects of Ball Milling and Extrusion Conditions on Microstructures and Resultant Composite Properties

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Acta Metallurgica Sinica(English Letters) 2019年第5期32卷 573-584页

作者： Fumio Ogawa Shuji yamamoto Chitoshi Masuda Department of Mechanical Engineering College of Science and Engineering Ritsumeikan University Kanto Gakuin University Kagami Memorial Institute for Materials Science and Technology Waseda University

Carbon nanofiber(CNF)-reinforced aluminum-matrix composites were fabricated via ball milling and spark plasma sintering(SPS), SPS followed by hot extrusion and powder extrusion. Two mixing conditions of CNF and aluminum powder were adopted: milling at 90 rpm and milling at 200 rpm. After milling at 90 rpm, the mixed powder was sintered using SPS at 560 °C. The composite was then extruded at 500 °C at an extrusion ratio of 9. Composites were also fabricated via powder extrusion of powder milled at 200 rpm and 550 °C with an extrusion ratio of 9(R9) or 16(R16). The thermal conductivity and tensile properties of the resultant composites were evaluated. Anisotropic thermal conductivity was observed even in the sintered products. The anisotropy could be controlled via hot extrusion. The thermal conductivity of composites fabricated via powder extrusion was higher than those fabricated using other methods. However, in the case of specimens with a CNF volume fraction of 4.0%, the thermal conductivity of the composite fabricated via SPS and hot extrusion was the highest. The highest thermal conductivity of 4.0% CNF-reinforced composite is attributable to networking and percolation of CNFs. The effect of the fabrication route on the tensile strength and ductility was also investigated. Tensile strengths of the R9 composites were the highest. By contrast, the R16 composites prepared under long heating duration exhibited high ductility at CNF volume fractions of 2.0% and 5.0%. The microstructures of composites and fracture surfaces were observed in detail, and fracture process was elucidated. The results revealed that controlling the heating and plastic deformation during extrusion will yield strong and ductile composites.

关键词： Al composite Carbon nanofiber Ball milling Hot extrusion Microstructure and performance

PHOTOCHROMISM AND LUMINESCENCE OF DOPANT CHROMOPHORES THROUGH TWO-PHOTON IONIZATION IN POLYMER FILMS

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Chinese Journal of Polymer Science 2001年第2期19卷 129-134页

作者： Masahide yamamoto Hideo Ohkita Shinzaburo Ito Faculty of Science and Engineering Ritsumeikan University Kusatsu Shiga 525-8577 JapanDepartment of Polymer Chemistry Graduate School of Engineering Kyoto University Sakyo Kyoto 606-8501 JapanDepartment of Polymer Chemistry Graduate School of Engineering Kyoto University Sakyo Kyoto 606-8501 Japan

Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic moleculehaving low ionization potential, e.g., N,N,N',N'-tetramethyl-p-phenylene diamine doped in poly(methyl methacrylate)(PMMA) film was easily photoionized by intense laser ligh excitation, giving a colored radical cation (photochromism) anda trapped electron in PMMA matrix. As a reversed process, the radical cation recombined with the trapped electron, showingdiscoloration and emitting luminescence, either isothermal luminescence (ITL), or thermoluminescence (TL). In this report,ITL and TL through the charge recombination process were studied and the luminescence was suggested as a mean of the read-out of photorecording.

关键词： Two-photon ionization Photochromism Charge recombination Trapped electron Isothermal luminescence Thermoluminescence Aromatic amines Poly(methyl methacrylate)