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Maeda, Yutaka,Higo, Junki,Amagai, Yuri,Matsui, Jun,Ohkubo, Kei,Yoshigoe, Yusuke,Hashimoto, Masahiro,Eguchi, Kazuhiro,Yamada, Michio,Hasegawa, Tadashi,Sato, Yoshinori,Zhou, Jing,Lu, Jing,Miyashita, Tok American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.16
<P>This report describes a helicity-selective photoreaction of single-walled carbon nanotubes (SWNTs) with disulfide in the presence of oxygen. The SWNTs were characterized using absorption, photoluminescence (PL), Raman, and X-ray photoelectron spectroscopy, scanning electron microscopy, and current–voltage (<I>I</I>–<I>V</I>) measurements. Results showed remarkable helicity-selective (metallic SWNTs/semiconducting SWNTs and diameter) functionalization of SWNTs. The reaction rate decreases in the order of metallic SWNTs > semiconducting SWNTs and small-diameter SWNTs > large-diameter SWNTs. Control experiments conducted under various experimental conditions and ESR and femtosecond laser flash photolysis measurements revealed that the helicity-selective reaction proceeds via a photoinduced electron transfer reaction. The PL and <I>I</I>–<I>V</I> measurements showed that the photoreaction is effective not only to control SWNT conductivity but also for the band gap modulation of semiconducting SWNTs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-16/ja402199n/production/images/medium/ja-2013-02199n_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja402199n'>ACS Electronic Supporting Info</A></P>
Maeda, Minoru,Choi, Seyong Elsevier 2019 Journal of alloys and compounds Vol.787 No.-
<P><B>Abstract</B></P> <P>Carbon-based organic molecular gas is a well-known chemical agent for controlling inorganic structures of MgB<SUB>2</SUB> single-crystal material. The utilization of such a gas can also be applied to polycrystalline materials. So far, however, few studies have dealt with the methodology and the effects, especially the structural mechanism. Herein, we have focused on hydrocarbon gas as an active carbon source for bulk and wire materials consisting of MgB<SUB>2</SUB> polycrystals. A starting material, amorphous or crystalline boron powder, was heated and exposed to the molecular gas in argon atmosphere. While the treated powder showed no major change in its structure, as characterized by X-ray diffraction profiles, its usage as a precursor powder for MgB<SUB>2</SUB> bulks resulted in a marked increase in the in-field critical current density. In order to examine and help identify the underlying causes, we have carried out further structural analysis with the Halder Wagner method, considering the integral breadths of peaks in the X-ray diffraction profiles. Finally, the gas treatment was found to improve the in-field transport properties, even for MgB<SUB>2</SUB> wires and densified conductors, which are made from crystalline boron powder.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carbon-based organic molecular gas can be utilized for MgB<SUB>2</SUB> bulk and wire materials. </LI> <LI> The precursor powder doesn't show major structural change after the gas treatment. </LI> <LI> In contrast, the structural order in MgB<SUB>2</SUB> lattice is lowered by the gas treatment. </LI> <LI> The modified structure leads to enhancement in the in-field transport property. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Maeda, Chihiro,Kim, Pyosang,Cho, Sung,Park, Jong Kang,Lim, Jong Min,Kim, Dongho,Vura-Weis, Josh,Wasielewski, Michael R.,Shinokubo, Hiroshi,Osuka, Atsuhiro WILEY-VCH Verlag 2010 Chemistry Vol.16 No.17
<P>meso-Triazolyl-appended Zn<SUP>II</SUP>–porphyrins were readily prepared by Cu<SUP>I</SUP>-catalyzed 1,3-dipolar cycloaddition of benzyl azide to meso-ethynylated Zn<SUP>II</SUP>–porphyrin (click chemistry). In noncoordinating CHCl<SUB>3</SUB> solvent, spontaneous assembly occurred to form tetrameric array (3)<SUB>2</SUB> from meso–meso-linked diporphyrins 3, and dodecameric porphyrin squares (4)<SUB>4</SUB> and (5)<SUB>4</SUB> from the L-shaped meso–meso-linked triporphyrins 4 and 5. The structures of these assemblies were examined by <SUP>1</SUP>H NMR spectra, absorption spectra, and their gel permeation chromatography (GPC) retention time. Furthermore, the structures of the dodecameric porphyrin squares (4)<SUB>4</SUB> and (5)<SUB>4</SUB> were probed by small- and wide-angle X-ray scattering (SAXS/WAXS) measurements in solution using a synchrotron source. Excitation-energy migration processes in these assemblies were also investigated in detail by using both steady-state and time-resolved spectroscopic methods, which revealed efficient excited-energy transfer (EET) between the meso–meso-linked Zn<SUP>II</SUP>–porphyrin units that occurred with time constants of 1.5 ps<SUP>−1</SUP> for (3)<SUB>2</SUB> and 8.8 ps<SUP>−1</SUP> for (5)<SUB>4</SUB>.</P> <B>Graphic Abstract</B> <P>Getting it together: In a noncoordinating solvent, spontaneous assembly occurs to form a tetrameric array from meso–meso-linked diporphyrins, and a dodecameric porphyrin square from L-shaped meso–meso-linked triporphyrins (see graphic). Efficient excited-energy transfer (EET) between the meso–meso-linked Zn<SUP>II</SUP>–porphyrin units was revealed. <img src='wiley_img_2010/09476539-2010-16-17-CHEM200903195-content.gif' alt='wiley_img_2010/09476539-2010-16-17-CHEM200903195-content'> </P>
Improvement in the Super Low Core-loss Soft Magnetic Materials
Maeda Toru,Sato Atsushi,Mochida Yasushi,Toyoda Haruhisa,Mimura Koji,Nishioka Takao 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
We reported a P/M soft magnetic material with core loss value of , which is lower than that of 0.35mm-thick laminated material, by using high purity gas-atomized iron powder. Lack of mechanical strength and high cost of powder production are significant issues for industrial use. In order to achieve both low core loss and high strength by using inexpencive powder, the improvement of powder shape and surface morphology and binder strength was conducted. As the result, the material based on water-atomized powder with 80 MPa of TRS and 108 W/kg of core loss (W10/1k) was achieved.
Study of Flow Field and Pressure Distribution on a Rotor Blade of HAWT in Yawed Flow Conditions
Maeda, Takao,Kamada, Yasunari,Okada, Naohiro,Suzuki, Jun Korean Society for Fluid machinery 2010 International journal of fluid machinery and syste Vol.3 No.4
This paper describes the flow field and the blade pressure distribution of a horizontal axis wind turbine in various yawed flow conditions. These measurements were carried out with 2.4m-diameter rotor with pressure sensors and a 2-dimensional laser Doppler velocimeter for each azimuth angle in a wind tunnel. The results show that aerodynamic forces of the blade based on the pressure measurements change according to the local angle of attack during rotation. Therefore the wake of the yawed rotor becomes asymmetric for the rotor axis. Furthermore, the relations between aerodynamic forces and azimuth angles change according to tip speed ratio. By the experimental analysis, the flow field and the aerodynamic forces for each azimuth angle in yawed flow condition were clarified.