Tokyo Institute of Technology

About: Tokyo Institute of Technology is a education organization based out in Tokyo, Tôkyô, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 46775 authors who have published 101656 publications receiving 2357893 citations. The organization is also known as: Tokyo Tech & Tokodai.

Geotail observations of magnetic flux ropes in the plasma sheet

Abstract: [1] Examination of Geotail measurements in the near-tail (X > � 30 RE) has revealed the presence of small flux ropes in the plasma sheet. A total of 73 flux rope events were identified in the Geotail magnetic field measurements between November 1998 and April 1999. This corresponds to an estimated occurrence frequency of � 1 flux rope per 5 hours of central plasma sheet observing time. All of the flux ropes were embedded within high-speed plasma sheet flows with 35 directed Earthward, hVxi = 431 km/s, and 38 moving tailward, hVxi = � 451 km/s. We refer to these two populations as ‘‘BBF-type’’ and ‘‘plasmoid-type’’ flux ropes. The flux ropes were usually several tens of seconds in duration, and the two types were readily distinguished by the sense of their quasisinusoidal Bz perturbations, i.e., � for the ‘‘BBF’’ events and ± for the ‘‘plasmoid’’ events. Most typically, a flux rope was observed to closely follow the onset of a high-speed flow within � 1–2 min. Application of the Lepping-Burlaga constant-a flux rope model (i.e., J = aB) to these events showed that approximately 60% of each class could be acceptably described as cylindrical, force-free flux ropes. The modeling results yielded mean flux rope diameters and core field intensities of 1.4 RE and 20 nT and 4.4 RE and 14 nT for the BBF and plasmoid-type events, respectively. The inclinations of the flux ropes were small relative to the GSM X–Y plane, but a wide range of azimuthal orientations were determined within that plane. The frequent presence of these flux ropes in the plasma sheet is interpreted as strong evidence for multiple reconnection X-lines (MRX) in the near-tail. Hence, our results suggest that reconnection in the near-tail may closely resemble that at the dayside magnetopause where MRX reconnection has been hypothesized to be responsible for the generation of flux transfer events. INDEX TERMS: 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2764 Magnetospheric Physics: Plasma sheet; 2744 Magnetospheric Physics: Magnetotail; 2788 Magnetospheric Physics: Storms and substorms

Highly Selective Two-Electron Oxygen Reduction Catalyzed by Mesoporous Nitrogen-Doped Carbon

Abstract: Electrochemical reduction of oxygen molecules can produce H2O2, which is an important chemical for a green and sustainable society; therefore, the development of catalysts for this reaction is necessary. We propose mesoporous nitrogen-doped carbon prepared from (1-methyl-1H-pyrrole-2-yl)methanol in the presence of a mesoporous SiO2 template (KIT-6). The nitrogen content of the resulting carbon can be controlled in the range of 0–10 at. % and all prepared samples have well-ordered mesopores with diameters of 3.4–4.0 nm. Electrochemical studies indicate the present materials have high catalytic activities with high selectivity toward H2O2 over 90%. Such high selectivity toward H2O2 is probably due to good mass transport in the catalyst layer, which is enhanced by the mesoporous structure.

Production of copolyesters of 3-hydroxybutyrate and 3-hydroxyvalerate by Alcaligenes eutrophus from butyric and pentanoic acids

Abstract: Copolyesters of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) have been produced by Alcaligenes eutrophus in nitrogenfree culture solutions of butyric and pentanoic acids. When pentanoic acid was used as the sole carbon source, a copolyester with an unusually high 3HV fraction of 90 mol% was produced. Copolyesters with a wide range of compositions (0–90 mol% 3HV) were obtained by using butyric and pentanoic acids together as carbon sources. The biosynthetic pathways of poly(3-hydroxybutyrate) were investigated using [1-13C]acetate and [1-13C]butyrate. It is suggested that butyric and pentanoic acids are incorporated into the copolyester as 3HB and 3HV units respectively without decomposition of the carbon skeletons in the cell.