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Synthesis and Magnetic Properties of DyMnO3 Nanoparticles in Mesoporous Silica
Takayuki Tajiri,Atsushi Kohno,Kenta Hamamoto,Yuhki Ando,Hiroyuki Deguchi,Masaki Mito 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We synthesized nanoparticles of the perovskite manganite DyMnO3 in pores of mesoporous silicaSBA-15 and investigated their magnetic properties. X-ray diffraction patterns of the nanoparticlesindicated successful synthesis of the DyMnO3 nanoparticles with a particle size of about 10 nmin the pores of SBA-15. The temperature dependence of the DC magnetic susceptibility for theDyMnO3 nanoparticles exhibited a pronounced magnetic irreversibility between the field-coolingand the zero-field-cooling susceptibility due to the blocking phenomena and indicated a change ofthe magnetic exchange interactions from those for the bulk crystal. The in-phase susceptibility χ" and the out-of-phase susceptibility χ" of the AC susceptibility for the nanoparticles exhibited apeak at the blocking temperature, and that peak shifted toward higher temperature with increasingfrequency. Magnetization curves for the nanoparticles were reproduced by using a Langevin functionand exhibited a hysteresis loop at temperatures below the blocking temperature. Magnetic sizeeffects and superparamagnetic behaviors were observed in the DyMnO3 nanoparticles.
Nakamura, Akihiko,Watanabe, Hiroki,Ishida, Takuya,Uchihashi, Takayuki,Wada, Masahisa,Ando, Toshio,Igarashi, Kiyohiko,Samejima, Masahiro American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.12
<P>Analysis of heterogeneous catalysis at an interface is difficult because of the variety of reaction sites and the difficulty of observing the reaction. Enzymatic hydrolysis of cellulose by cellulases is a typical heterogeneous reaction at a solid/liquid interface, and a key parameter of such reactions on polymeric substrates is the processivity, i.e., the number of catalytic cycles that can occur without detachment of the enzyme from the substrate. In this study, we evaluated the reactions of three closely related glycoside hydrolase family 7 cellobiohydrolases from filamentous fungi at the molecular level by means of high-speed atomic force microscopy to investigate the structure–function relationship of the cellobiohydrolases on crystalline cellulose. We found that high moving velocity of enzyme molecules on the surface is associated with a high dissociation rate constant from the substrate, which means weak interaction between enzyme and substrate. Moreover, higher values of processivity were associated with more loop regions covering the subsite cleft, which may imply higher binding affinity. Loop regions covering the subsites result in stronger interaction, which decreases the velocity but increases the processivity. These results indicate that there is a trade-off between processivity and hydrolytic velocity among processive cellulases.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-12/ja4119994/production/images/medium/ja-2013-119994_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja4119994'>ACS Electronic Supporting Info</A></P>
Management of Remnant or Recurrent Lesions after Endoscopic Papillectomy
Ichiro Yasuda,Saito Kobayashi,Kosuke Takahashi,Sohachi Nanjo,Hiroshi Mihara,Shinya Kajiura,Takayuki Ando,Kazuto Tajiri,Haruka Fujinami 대한소화기내시경학회 2020 Clinical Endoscopy Vol.53 No.6
Endoscopic papillectomy (EP) for ampullary adenomas achieves cure rates ranging from 76% to 90%, and recurrence rates are as high as 33%. If remnant or recurrent lesions after prior EP are endoscopically visible and are not suspected of intraductal extension into the biliary or pancreatic duct, repeated snaring and cutting can be performed until all visible lesions are completely resected. However, endoscopic ablative therapies, particularly argon plasma coagulation, can be attempted for tiny or uncertain remnant and recurrent lesions. In addition, intraductal radiofrequency ablation has recently been attempted for residual intraductal lesions after EP at several institutions. Although still under investigation, it has shown some promise. It might be offered as an alternative to surgery, particularly in patients who are unfit for surgery or those who refuse to undergo surgery