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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)

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

Numerical Simulation on Supersonic Flow in High-Velocity Oxy-Fuel Thermal Spray Gun

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Journal of Thermal Science 2006年第1期15卷 65-70页

作者： Hiroshi KATANODA Hideki yamamoto Kazuyasu MATSUO The University of Kitakyushu 1-1 Hibikino Wakamatsu-ku Kitakyushu Fukuoka 808-0135 Japan

This paper analyzes the behaviour of coating particles as well as the gas flow both inside and outside of the High-Velocity Oxy-Fuel （HVOF） thermal spray gun by using a quasi-one-dimensional analysis and a numerical simulation. The HVOF gun in the present analysis is an axially symmetric convergent-divergent nozzle with the design Math number of 2.0. From the present analysis, the distributions of veloeity and temperature of the coating particles flying inside and outside of the HVOF gun are predicted. The velocity and temperature of the coating particles at the exit of the gun calculated by the present method agree well with the previous experimental results. Therefore, the present method of calculation is considered to be useful for predicting the HVOF gas and particle flows.

关键词： compressible flow supersonic jet thermal spray HVOF.

Genetic factors associated with the development of inflammatory bowel disease

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World Journal of Gastroenterology 2007年第42期13卷 5594-5597页

作者： Jesus K yamamoto-Furusho Inflammatory Bowel DiseaseClinic Department of Gastroenterology Instituto Nacional deCiencias Médicas y Nutrición Vasco de Quiroga 15 ColoniaSección XVI Tlalpan C.P. 14000 México D.F. México

Crohn's disease(CD)and ulcerative colitis(UC)are complex polygenic disorders,characterized by several genes together with environmental factors contributing to the development of inflammatory bowel disease(IBD).Recent advances in research on genetic susceptibility have allowed the identification of diverse genes at different levels:(1)Innate immunity;(2)Antigen presentation molecules;(3)Epithelial integrity;(4)Drug transporter;(5)Cell *** application of genetic testing into clinical practice is close and all genetic markers may have several clinical implications:prediction of disease phenotype,molecular classification,prevention of complications,and prognosis.

关键词： Genetic Susceptibility Inflammatory bowel disease Ulcerative colitis Crohn's disease

Stability of Inverse Problems for Ultrahyperbolic Equations

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Chinese Annals of Mathematics,Series B 2014年第4期35卷 527-556页

作者： Fikret G?LGELEYEN Masahiro yamamoto Department of Mathematics Bülent Ecevit University Zonguldak 67100 Turkey Department of Mathematical Sciences The University of Tokyo 3-8-1 Komaba Meguro Tokyo 1538914 Japan

In this paper, the authors consider inverse problems of determining a coemcient or a source term in an ultrahyperbolic equation by some lateral boundary data. The authors prove HSlder estimates which are global and lo... 详细信息

关键词： Ultrahyperbolic equation Inverse problem Stability Carleman estimate

Human umbilical cord-derived mesenchymal stromal cells promote sensory recovery in a spinal cord injury rat model

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Stem Cell Discovery 2013年第3期3卷 155-163页

作者： sachiko Takikawa Akihito yamamoto Kiyoshi Sakai Ryutaro Shohara Akira Iwase Fumitaka Kikkawa Minoru Ueda Department of Oral and Maxillofacial Surgery Nagoya University Graduate School of Medicine Nagoya Japan

While paralysis is widely appreciated to impact the quality-of-life after spinal cord injuries (SCIs), neuropathic chronic pain may also occur in many cases. In this study, we investigated whether human umbilical cord-derived mesenchymal stromal cells (hUCMSCs) possess the therapeutic potential to reduce neuropathic pain following SCI in rats. Spinal cord hemitransection, which was used as a rat SCI pain model, induced tactile hypersensitivity in the hind paw and hyperexcitability of wild dynamic range neurons in response to natural cutaneous stimuli. Following hemitransection, we transplanted hUCMSCs into the spinal cord. Attenuation of neuronal hyperexcitability was observed in the hUCMSC-treated group compared with that observed in the vehicle-treated group. Immunohistochemistry showed that the transplanted hUCMSCs retained the expression of gammaamino butyric acid (GABA). The results suggest that transplanted hUCMSCs ameliorate GABAergic inhibition in the spinal cord. In summary, the production of GABA plays a critical role in the plasticity of neuropathic pain after implantation of hUCMSCs.

关键词： Human Umbilical Cord Mesenchymal Stromal Cell Mesenchymal Stem Cell GABA

Boundary Conditions for Combustion Field and LB Simulation of Diesel Particulate Filter

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Communications in Computational Physics 2013年第3期13卷 769-779页

作者： Kazuhiro yamamoto Department of Mechanical Science and Engineering Faculty of EngineeringNagoya UniversityFuro-choChikusa-kuNagoya464-8603 Japan

A diesel particulate filter(DPF)is a key technology to meet future emission standards of particulate matters(PM),mainly *** is generally consists of a wall-flow type filter positioned in the exhaust stream of a diesel *** is difficult to simulate the thermal flow in DPF,because we need to consider the soot deposition and combustion in the complex geometry of filter *** our previous study,we proposed an approach for the conjugate simulation of gas-solid *** is,the gas phase was simulated by the lattice Boltzmann method(LBM),coupled with the equation of heat conduction inside the solid filter ***,its numerical procedure was slightly *** this study,to reduce numerical costs,we have tested a new boundary condition with chemical equilibrium in soot combustion at the surface of filter *** on the soot oxidation rate with catalysts evaluated in experiments,the lattice Boltzmann simulation of soot combustion in the catalyzed DPF is firstly presented to consider the process in the after-treatment of diesel exhaust *** heat and mass transfer is shown to discuss the effect of catalysts.

关键词： Lattice Boltzmann method DPF heat conduction X-ray CT multiphase flow

Precipitation of Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

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材料热处理学报 2004年第5期25卷 229-233页

作者： Keisuke yamamoto Yoshisato Kimura Yoshinao Mishima Department of Materials Science and Engineering Tokyo Institute of Technology Yokohama JapanDepartment of Materials Science and Engineering Tokyo Institute of Technology Yokohama JapanDepartment of Materials Science and Engineering Tokyo Institute of Technology Yokohama Japan

Ferritic heat resistant steels involving precipitation of intermetallic phases have drawn a growing interest for the enhancement of creep strength, while the brittleness of the intermetallic phases may lower the toughness of the alloy. Therefore, it is necessary to optimize the dispersion characteristics of the intermetallics phase through microstructural control to minimize the trade-off between the strength and toughness. The effects of -Fe matrix substructures on the precipitation sequence, morphology, dispersion characteristics, and the stability of the intermetallic phases are investigated in Fe-Cr-W-Co-Si system. The precipitates of the Si-free Fe-10Cr-l.4W-4.5Co (at%) alloy aged at 873K are the R-phase but those of the Si-added Fe-10Cr-l.4W-4.5Co-0.3Si (at%) alloy are the icosahedral quasicrystalline phase. The precipitates in both the Si-free and Si-added alloys aged at 973K are the Laves phase. Matrix of the alloys is controlled by heat treatments as to provide three types of matrix substructures; ferrite, ferrite/martensite mixture and martensite. The hardening behavior of the alloys depends on the matrix substructures and is independent of the kinds of precipitates. In the alloys with ferrite matrix, the peak of hardness during aging at 873K shifts to longer aging time in comparison with that in the alloys with lath martensite matrix which contain numbers of nucleation sites.

关键词：过渡电子扫描仪准晶体 R相拉夫斯相铁素体钢

Numerical Investigation on Detonation Wave through U-bend

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Journal of Thermal Science 2010年第6期19卷 540-544页

作者： Shinobu Otsuka Masaya Suzuki Makoto yamamoto Department of Mechanical Engineering Tokyo University of Science

Pulse detonation engine (PDE) is expected for a next-generation propulsion system. PDE is a promising engine that can generates power and thrust by using intermittent detonation. Promotion of deflagration to detonation transition (below DDT) is a key issue to realize this system. PDE has experimentally been investigated, and it was confirmed that detonation tubes with U-shaped bends are useful for fast DDT. However, the mechanism of DDT promotion due to U-bends has not been well clarified. In the present study, the influence of a U-bend on detona-tion wave propagation is researched with computational fluid dynamics (CFD). The numerical results show that detonation wave disappears once near the U-bend inlet and restarts after passing through it. In addition, it was found that the use of the U-bend with small channel width and curvature radius can induce fast DDT.

关键词： Detonation Deflagration to Detonation Transition (DDT) U-bend Computational Fluid Dynamics