Ultrasonic attenuation monitoring of fatigue damage in low carbon steels with electromagnetic acoustic resonance (EMAR)

We studied microstructure evolution during tension-compression fatigue in low carbon steels, containing C: 0.15 mass%. In situ monitoring of axial-shear-wave attenuation and velocity was achieved with electromagnetic acoustic resonance (EMAR), which is a combination of the resonant spectroscopy technique and a noncontacting electromagnetic acoustic transducer (EMAT). Transduction occurs with the magnetostriction effect and is the key to establish a continuous monitoring of microstructural changes in the surface region of the metals with high sensitivity. We found for the first time that the attenuation is highly sensitive to the accumulated fatigue damage, showing a minimum around 20% of the whole life. This phenomenon is interpreted in terms of drastic change of dislocation mobility and rearrangement, which is supported by TEM observation for dislocation structure. This technique has the potential to assess the damage advance and to predict the fatigue life of metals.     

固溶处理对添加Si的Cu-10Ni-8Sn合金胞状沉淀的影响

利用定量金相的方法,研究了固溶-退火条件(温度和时间)对添加0.2%Si的Cu-10Ni-8Sn合金450℃时效时晶界处胞状物的形核与长大的影响.在450℃时效过程中,基体的硬度几乎不受固溶-退火条件的影响.然而,时效过程中固溶-退火条件对胞状物的形核与长大的影响却非常显著.当固溶-退火温度或时间增加时,Si对于胞状沉淀的抑制作用下降.随固溶-退火温度或者时间的增加,淬火态样品中存在于基体晶粒和晶界上的Ni31Si12相颗粒被粗化.因此,可以认为,经较高温度或较长时间固溶-退火的样品时效时,Ni31Si12相颗粒占据胞状物在晶界上的形核位置并抑制胞状物前沿界面迁移的作用降低了.     

Indentation creep in nanocrystalline Fe-TiN and Ni-TiN alloys prepared by mechanical alloying

Mechanical properties of nanocrystalline Fe-TiN and Ni-TiN alloys with various TiN contents between 17 and 64 vol pct, which are prepared by dynamically consolidating mechanically alloyed powders, have been investigated by means of hardness measurements and indentation creep tests at intermediate temperatures. The hardness increases with decreasing grain size to about 10 nm. The indentation creep curves conform well to an equation derived from a transient creep rate equation. The analysis of creep curves indicates that the deformation occurs by a dislocation mechanism controlled by grain boundary diffusion.     

Biochemical characterization of l-arabitol 2-dehydrogenase from Pantoea ananatis

Two oxidoreductases, XDH and LAD, were found in the same operon that was involved in sugar metabolism in Pantoea ananatis. LAD, whose endogenous substrate was unknown, was recombinantly prepared and biochemically analyzed. Consequently, LAD was identified as l-arabitol 2-dehydrogenase and its substrate specificity was complementary to that of XDH.     

Definition of the mitogenic factor (MF) as a novel streptococcal superantigen that is different from streptococcal pyrogenic exotoxins A, B, and C

Human T cell activation by recombinant mitogenic factor (rMF) was investigated in comparison with that by recombinant streptococcal pyrogenic exotoxins (rSPE) A, B, and C. Recombinant MF, rSPEA, and rSPEC were mitogenic for peripheral blood mononuclear cells (PBMC), whereas rSPEB was not. Recombinant MF required only HLA-DR for the stimulation of PBMC, as determined using monoclonal antibodies (mAb) to HLA class II molecules and the mouse L cells transfected with HLA class II molecules. Recombinant SPEA and rSPEC required HLA-DR or HLA-DQ molecule. Recombinant MF selectively stimulated V beta 2, V beta 7, V beta 8, V beta 18 and V beta 21-bearing T cells, whereas rSPEA and rSPEC activated V beta 2 and V beta 6-bearing T cells as evaluated by the quantitative T cell receptor (TCR) analytical method. No clonality was observed in the nucleotide sequences of complementarity determining region 3 of TCR V beta in T cells responding to rMF. The profiles of cytokine production by PBMC in response to rMF, rSPEA, and rSPEC were quite similar. In summary, these results demonstrate that both HLA class II molecules and the TCR V beta required for rMF-mediated T cell activation are distinct from those required for rSPEA or rSPEC-mediated activation. Therefore, the MF is a novel streptococcal super-antigen which is different from SPEA, SPEB, and SPEC.     

Effects of bleaching variables on residual sulfite content of salted jelly-fish

Summary The effects of bleaching variables on the residual sulfite content of jelly-fish were evaluated. The primary factor that affects the residual sulfite content appears to be the concentration of sodium bisulfite used as bleaching agent. The use of sodium bisulfite of less than 300 mg/kg as SO₂ the legally regulated level (below 30 mg/kg as SO₂). The ratio of combined to total sulfite was not less than 90% regardless of the total sulfite content.

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Einflüsse von Bleichbedingungen auf den Sulfitgehalt der gesalzenen Qualle

Zusammenfassung Es wurden die Einflüsse von Bleichbedingungen auf den Sulfitgehalt der Qualle untersucht. Der primäre Faktor, der den bleibenden Sulfitgehalt der Qualle bewirkt, war die Konzentration von Natriumbisulfit. Der verbleibende Sulfitgehalt in der Qualle, die mit Natriumbisulfit von 100–300 mg/kg (als SO₂) gebleicht wurde, betrug weniger als 30 mg/kg. Das Verhältnis von gebundenem Sulfit zu Gesamtsulfit betrug 9:1.

     

Fabrication of Ternary Phase Composition-Spread Thin Film Libraries and Their High-Throughput Characterization: Ti1?x?yZrxHfyO2 for Bandgap Engineering

Ternary phase composition-spread thin film libraries, TiO₂-ZrO₂-HfO₂, were synthesized by using a combinatorial pulsed laser deposition system. The composition, crystalline structure, and optical transmission properties were characterized in a high-throughput way. TiO₂ doped with Zr and Hf was found to exhibit a wider bandgap than pure TiO₂; hence, these compounds can be used as wide gap semiconductors for heteroepitaxial spintronics devices, based on a ferromagnetic semiconductor, Co-doped TiO₂.     

An approach to discovering risks in development process of large and complex systems

When building a large and complex system, such as satellites, all sorts of risks have to be managed if it were to be successful. For risks in the design of an artifact, various reliability analysis techniques such as FTA or FMEA have been employed in the engineering domain. However, risks exist as well in the development process, and they could result in a failure of the system. In this paper, we present an approach to discovering risks in development process by collecting and organizing information produced during development process at low cost. We describe a prototype system called IDIMS, and show how it can be used to discover risks from e-mail communications between developers. The motivation of our work is to overcome thecapture bottleneck problem, and utilize now wasted information to improve development process. Yoshikiyo Kato: He received his B. Eng. (1998) and M.Eng. (2000) degrees in aeronautics and astronautics from The University of Tokyo. From September 1998 to July 1999, he was an exchange student at Department of Computer Science and Engineering of University of California, San Diego, and worked on software engineering tools. From May 2001 to July 2002, he was a research assistant at National Institute of Informatics (Japan). He is currently a Ph.D. student at Department of Advanced Interdisciplinary Studies of the University of Tokyo. His research interests include knowledge management, CSCW, HCI and software engineering He is a member of AAAI and JSAI. Takahiro Shirakawa: He received his B.Eng. (2000) and M.Eng. (2002) degrees in aeronautics and astronautics from the University of Tokyo. He is currently an assistant examiner at Japan Patent Office. Kohei Taketa: He received his B.Eng. (2000) and M.Eng. (2002) degrees in aeronautics and astronautics from the University of Tokyo. He is currently a software engineer at NTT Data Corp. Koichi Hori, Dr.Eng.: He received B.Eng, M.Eng, and Dr.Eng. degrees in electronic engineering from the University of Tokyo, Japan, in 1979, 1981, and 1984, respectively. In 1984, he joined National Institute of Japanese Literature where he developed AI systems for literature studies. Since 1988, he has been with the U University of Tokyo. He is currently a professor with Department of Advanced Interdisciplinary Studies, The University of Tokyo. From September 1989 to January 1990, he also held a visiting position at University of Compiegne, France. His current research interests include AI technology for supporting human creative activities, cognitive engineering, and Intelligent CAD systems. He is a member of IEEE, ACM, IEICE, IPSJ, JSAI, JSSST and JCSS.