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        검색결과 7

        1.
        2008.10 구독 인증기관·개인회원 무료
        Borrelia, which is transmitted by arthropod, is known as an infectious agent to vertebrate, such as Lyme disease (LD) Borrelia and Relapsing fever (RF) Borrelia. LD Borrelia is only transmitted by hard-bodied ticks classified into the Ixodes ticks. In contrast, almost of RF Borrelia was transmitted by soft-bodied ticks, Argasid ticks. Thus so far, the co-evolution was thought to be established between Borrelia and tick. In this study, we found unknown borreliae from imported reptiles and its associated ticks (we preliminary named as ‘REP Borrelia’). Ticks were introduced into Japan with world-wide trading of reptiles. Ticks were classified into genus Amblyomma or Hyalomma. Out of 82 ticks, 76 were positive for PCR of tickmitochondrial gene for 16S rRNA, and we used these 76 ticks for our examination. From 57 ticks (75%), Borrelia turcica and unknown three Borrelia spp. were detected or isolated. In addition, we examined imported reptiles which were infested exotic ticks. A total of 15 reptiles including 5 of Testudo graeca, 1 of T. horsfieldii, 2 of Phelsuma dubia and 7 of Geochelone pardalis were used for isolation study of Borrelia. Borrelia was isolated from 11 reptiles (73.3%) as follows: T. graeca, T. horsfieldii, G. pardalis. It suggested that, these imported reptiles and exotic ticks were highly infected with Borrelia. Phylogenetic analysis based on the DNA sequences of Borrelia, it was indicated that REP Borrelia constituted a cluster which was independent from RF and LD Borrelia. Surprisingly, this REP Borrelia was expected that was transmitted by hard-bodied tick, although it was thought to be diverged from ancestor RF Borrelia. From quantitative analysis of divergence based on 16S rRNA gene, it was expected that REP and RF Borrelia were differentiated around 50 million years ago (MYA). On the other hand, the oldest soft-bodied tick fossil from New Jersey amber was indicated that soft-bodied tick was speciated since ~92 MYA. In fact, soft-bodied tick was already diverged into genus level when RF and REP Borrelia were diverged. This may suggest that the vector switching event was occurred in ancestor REP/RF Borrelia.
        2.
        2006.09 구독 인증기관·개인회원 무료
        Lanthanide tantalite (Ln= La, Nd, Sm, Dy, Er and Tm) was synthesized by a solid state reaction between mixed powders of and . The single-phase was prepared by sintering at temperatures of 1423-1673 K in air. The SEM observation showed that the particles were provided with the growth steps and the depeloped facets. The photocatalytic activity for water splitting of prepared was measured under UV light irradiation. The activity obtained was higher than that previously reported. These results suggested the crystallinity of photocatalysts correlates closely with the efficiency of water splitting.
        3.
        2006.09 구독 인증기관·개인회원 무료
        New Al-based alloys with very high ultimate tensile strength were developed in high Al concentration range of 91-95 at.% for Al-Fe-Cr-Ti-M (M: Co and Mo) systems and Al-Fe-Cr-Mo-Ti-Co system by the dispersion of nanoscale quasicrystalline particles in Al phase. The effect of adding elements, M was discussed in the viewpoint of stability of super-cooled liquid state and formation ability of quasicrystalline phase. The P/M Al-Fe-Cr-Ti-M alloys with dispersed nanoscale quasicrystalline particles exhibited ultimate tensile strength of 350MPa at 573K and 200MPa at 673K.
        4.
        2006.04 구독 인증기관·개인회원 무료
        Thermoelectric conversion efficiency of thermoelectric elements can be increased by using a structure combining n-type and p-type semiconductors. From the above point of view, attention was directed at ZnO as a candidate n-type semiconductor material and investigations were made. As the result, a dimensionless figure of merit ZT close to 0.28 (1073K) was obtained for specimens produced by the PCS (Pulse Current Sintering) method with addition of specified quantities of , CoO, and to ZnO. It was found that the interstitial in the ZnO restrains the grain growth and CoO acts onto the bond between grains. The influence of the inclusion of and CoO onto the sintering behavior also was investigated.
        5.
        2006.04 구독 인증기관·개인회원 무료
        The influence of the internal current for the ZnO ceramics on the sintering behavior by pulse current sintering (PCS) method was investigated. To clear the dependence of inner current on the sintering behavior of ZnO ceramics, direct measurement of electric resistance of ZnO specimen under sintering by SPS device was carried out. It was observed that electric resistance of specimen decreases with increase in the temperature. The electric resistance begins to decrease from the low temperature of . The internal structure of sintered ZnO ceramics changed by the control of the internal current in the specimen using plate.
        6.
        2006.04 구독 인증기관·개인회원 무료
        The spherical and high quality Titanium fine powder "Tilop" has been produced with gas atomization furnace, Sumitomo Titanium Corporation originally designed. Recently, a new process which can produce Ti-alloy(Ti-6Al-4V) powders by utilizing our gas atomization process, of which raw material is sponge titanium pre-mixed with alloy chips or granules has been also developed. The particle size of gas atomized Ti-alloy powder and the mechanical properties of sintered Ti-alloy compacts prepared by metal injection molding were discussed in this study.
        7.
        2000.12 KCI 등재 서비스 종료(열람 제한)
        This paper introduces the equivalent frequency response method(EFRM) into runoff analysis. This EFRM originally had been developed to analyze dynamic behavior of nonlinear elements such as threshold and saturation in control engineering. Many runoff model