10 results on '"Yoichi Hirano"'
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2. Total Synthesis of Bis-anthraquinone Antibiotic BE-43472B.
- Author
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Yu Yamashita, Yoichi Hirano, Akiomi Takada, Hiroshi Takikawa, and Keisuke Suzuki
- Subjects
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ANTINEOPLASTIC antibiotics , *ANTHRAQUINONES , *BENZOIN , *POLYKETIDES , *HYDROXYL group , *LACTOLS , *OXIDATION , *DEHYDROGENATION - Abstract
This is a full account of our synthetic endeavor on the total synthesis of bis-anthraquinone antibiotic BE-43472B, an unusual octacyclic aromatic polyketide with a bis-anthraquinone scaffold. Three key steps enabled a facile access to the anthraquinone unit corresponding to the ABCF rings; (1) cyclo-condensation or -addition of benzonitrile oxides with cyclic enone derivatives, (2) benzoin cyclization for the stereoselective ring fusion with an angular hydroxy group, and (3) pinacol rearrangement for stereoselective installation of the angular aryl group. Other keys for the success include, (4) diastereoselective methylation of a lactol derivative, and (5) late-stage installation of the C3 hydroxy group through stereoselective oxirane ring formation via halohydrin derivatives. Whereas oxidation of the double bond in the enone with an adjacent 1,3-diketone moiety failed, the projected oxidation was achieved with the alkene keeping the isoxazole moiety intact as a 1,3-diketone equivalent. In the racemic total synthesis, X-ray crystal structure analysis of the target was achieved, proving the three-dimensional architecture for the first time. The asymmetric total synthesis was also achieved by exploiting a cycloadduct of the nitrile oxide and the enantiomerically pure cyclohexenone, which was convertible to the common intermediate via dehydrogenation followed by alkoxycarbonylation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
3. Overview of the RFX fusion science program
- Author
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M. Gobbin, Roberto Pasqualotto, D. Bonfiglio, Enrico Zilli, Giuseppe Marchiori, Piero Martin, S. Martini, Fulvio Auriemma, E. Gazza, D.K. Mansfield, P. Zaccaria, Piergiorgio Sonato, S. Ortolani, Wolf-Dieter Schneider, D. Yadikin, Stefano Munaretto, L. Piron, M. Valisa, Fabio Sattin, Susanna Cappello, G. V. Perverezev, F. Milani, Roberto Paccagnella, Paolo Bettini, S. Fiameni, Roscoe White, A. Ruzzon, V. Antoni, Leonardo Giudicotti, Yueqiang Liu, Lionello Marrelli, Nicola Vianello, S. Dal Bello, A. Scaggion, V. Rigato, Fabio Villone, A. Zamengo, Federica Bonomo, R. Cavazzana, M. Baruzzo, L. Carraro, F. Fantini, Giuseppe Zollino, Barbara Zaniol, Rita Lorenzini, Luis Chacon, X. Garbet, C. Angioni, Andrea Rizzolo, G. De Masi, G. Rostagni, W. A. Cooper, Manabu Takechi, Piero Agostinetti, Paolo Scarin, A. Pizzimenti, Yongkyoon In, Sheena Menmuir, Silvia Spagnolo, M. Moresco, Satoru Kiyama, S. P. Hirshman, M. Okabayashi, Giuseppe Chitarin, S. C. Guo, Gabriele Manduchi, Dominique Escande, Gianluigi Serianni, Alessandro Fassina, Luca Grando, Simona Barison, Allen H. Boozer, Michael Drevlak, Diego Marcuzzi, M. Pavei, J.Q. Dong, Anton Soppelsa, B. Momo, Gianluca Spizzo, Hajime Sakakita, Neil Pomphrey, Shunsuke Ide, Donald A. Spong, J. S. Sarff, Alessandra Canton, D. Lopez Bruna, M. Brombin, Matteo Zuin, T. Bolzonella, R. Piovan, Songfen Liu, Alberto Ferro, Italo Predebon, V. Igochine, L. Zanotto, Simone Peruzzo, Elena Gaio, P. Piovesan, Cesare Taliercio, J. Adamek, Go Matsunaga, P. Zanca, A. Buffa, M. Veranda, N. Pomaro, M. Spolaore, Oliviero Barana, Francesco Gnesotto, Emilio Martines, M. Dalla Palma, Paolo Franz, David Terranova, Yoichi Hirano, Matteo Agostini, G. Mazzitelli, Alberto Alfier, L. Novello, Vanni Toigo, M. Boldrin, R. Delogu, Guglielmo Rubinacci, Maria Ester Puiatti, A. Fiorentin, Karsten McCollam, E. Spada, M. Cavinato, A. De Lorenzi, L. Apolloni, J. Brotankova, F. Fellin, P. Innocente, Raul Sanchez, Zhirui Wang, Adriano Luchetta, Martin, P, Adamek, J, Agostinetti, P, Agostini, M, Alfier, A, Angioni, C, Antoni, V, Apolloni, L, Auriemma, F, Barana, O, Barison, S, Baruzzo, M, Bettini, P, Boldrin, M, Bolzonella, T, Bonfiglio, D, Bonomo, F, Boozer, A, Brombin, M, Brotankova, J, Buffa, A, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cavinato, M, Chacon, L, Chitarin, G, Cooper, W, Dal Bello, S, Dalla Palma, M, Delogu, R, De Lorenzi, A, De Masi, G, Dong, J, Drevlak, M, Escande, D, Fantini, F, Fassina, A, Fellin, F, Ferro, A, Fiameni, S, Fiorentin, A, Franz, P, Gaio, E, Garbet, X, Gazza, E, Giudicotti, L, Gnesotto, F, Gobbin, M, Grando, L, Guo, S, Hirano, Y, Hirshman, S, Ide, S, Igochine, V, In, Y, Innocente, P, Kiyama, S, Liu, S, Liu, Y, Bruna, D, Lorenzini, R, Luchetta, A, Manduchi, G, Mansfield, D, Marchiori, G, Marcuzzi, D, Marrelli, L, Martini, S, Matsunaga, G, Martines, E, Mazzitelli, G, Mccollam, K, Menmuir, S, Milani, F, Momo, B, Moresco, M, Munaretto, S, Novello, L, Okabayashi, M, Ortolani, S, Paccagnella, R, Pasqualotto, R, Pavei, M, Perverezev, G, Peruzzo, S, Piovan, R, Piovesan, P, Piron, L, Pizzimenti, A, Pomaro, N, Pomphrey, N, Predebon, I, Puiatti, M, Rigato, V, Rizzolo, A, Rostagni, G, Rubinacci, G, Ruzzon, A, Sakakita, H, Sanchez, R, Sarff, J, Sattin, F, Scaggion, A, Scarin, P, Schneider, W, Serianni, G, Sonato, P, Spada, E, Soppelsa, A, Spagnolo, S, Spolaore, M, Spong, D, Spizzo, G, Takechi, M, Taliercio, C, Terranova, D, Toigo, V, Valisa, M, Veranda, M, Vianello, N, Villone, F, Wang, Z, White, R, Yadikin, D, Zaccaria, P, Zamengo, A, Zanca, P, Zaniol, B, Zanotto, L, Zilli, E, Zollino, G, Zuin, M, Martin, P., Adamek, J., Agostinetti, P., Agostini, M., Alfier, A., Angioni, C., Antoni, V., Apolloni, L., Auriemma, F., Barana, O., Barison, S., Baruzzo, M., Bettini, P., Boldrin, M., Bolzonella, T., Bonfiglio, D., Bonomo, F., Boozer, A. H., Brombin, M., Brotankova, J., Buffa, A., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Chacon, L., Chitarin, G., Cooper, W. A., Bello, S. D., Palma, M. D., Delogu, R., Lorenzi, A. D., Masi, G. D., Dong, J. Q., Drevlak, M., Escande, D. F., Fantini, F., Fassina, A., Fellin, F., Ferro, A., Fiameni, S., Fiorentin, A., Franz, P., Gaio, E., Garbet, X., Gazza, E., Giudicotti, L., Gnesotto, F., Gobbin, M., Grando, L., Guo, S. C., Hirano, Y., Hirshman, S. P., Ide, S., Igochine, V., In, Y., Innocente, P., Kiyama, S., Liu, S. F., Liu, Y. Q., Bruna, D. L., Lorenzini, R., Luchetta, A., Manduchi, G., Mansfield, D. K., Marchiori, G., Marcuzzi, D., Marrelli, L., Martini, S., Matsunaga, G., Martines, E., Mazzitelli, G., Mccollam, K., Menmuir, S., Milani, F., Momo, B., Moresco, M., Munaretto, S., Novello, L., Okabayashi, M., Ortolani, S., Paccagnella, R., Pasqualotto, R., Pavei, M., Perverezev, G. V., Peruzzo, S., Piovan, R., Piovesan, P., Piron, L., Pizzimenti, A., Pomaro, N., Pomphrey, N., Predebon, I., Puiatti, M. E., Rigato, V., Rizzolo, A., Rostagni, G., Rubinacci, Guglielmo, Ruzzon, A., Sakakita, H., Sanchez, R., Sarff, J. S., Sattin, F., Scaggion, A., Scarin, P., Schneider, W., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spolaore, M., Spong, D. A., Spizzo, G., Takechi, M., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Veranda, M., Vianello, N., Villone, F., Wang, Z., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zollino, G., and Zuin, M.
- Subjects
Nuclear and High Energy Physics ,RFX-mod ,Tokamak ,Nuclear engineering ,PLASMAS ,CONFINEMENT ,reversed field pinch ,magnetic confinement ,law.invention ,law ,Physics::Plasma Physics ,RFP ,Scaling ,Mod ,Physics ,Reversed field pinch ,STABILITY ,Magnetic confinement fusion ,INTERNAL TRANSPORT BARRIER ,Plasma ,Fusion power ,Condensed Matter Physics ,REVERSED-FIELD-PINCH ,Atomic physics ,Magnetohydrodynamics ,Stellarator - Abstract
This paper summarizes the main achievements of the RFX fusion science program in the period between the 2008 and 2010 IAEA Fusion Energy Conferences. RFX-mod is the largest reversed field pinch in the world, equipped with a system of 192 coils for active control of MHD stability. The discovery and understanding of helical states with electron internal transport barriers and core electron temperature >1.5 keV significantly advances the perspectives of the configuration. Optimized experiments with plasma current up to 1.8 MA have been realized, confirming positive scaling. The first evidence of edge transport barriers is presented. Progress has been made also in the control of first-wall properties and of density profiles, with initial first-wall lithization experiments. Micro-turbulence mechanisms such as ion temperature gradient and micro-tearing are discussed in the framework of understanding gradient-driven transport in low magnetic chaos helical regimes. Both tearing mode and resistive wall mode active control have been optimized and experimental data have been used to benchmark numerical codes. The RFX programme also provides important results for the fusion community and in particular for tokamaks and stellarators on feedback control of MHD stability and on three-dimensional physics. On the latter topic, the result of the application of stellarator codes to describe three-dimensional reversed field pinch physics will be presented. © 2011 IAEA, Vienna.
- Published
- 2011
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4. High Beta and High Density Operation in TPE-RX
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Fulvio Auriemma, Paolo Innocente, Haruhisa Koguchi, Hajime Sakakita, Kiyoyuki Yambe, David Terranova, Yoichi Hirano, Satoru Kiyama, and Tomohiko Asai
- Subjects
Toroid ,Materials science ,Particle number ,reversed-field pinch (RFP) ,Plasma ,Condensed Matter Physics ,pulsed poloidal current drive (PPCD) ,Deuterium ,Beta (plasma physics) ,Pinch ,Particle ,Electron temperature ,high-beta plasma ,Atomic physics ,pellet injection - Abstract
A high poloidal beta, βp, was achieved using pulsed poloidal current drive (PPCD) in a toroidal pinch experiment-RX (TPE-RX). The plasma electron density and temperature increased, hence improving βp from 5 to 30% during PPCD. βp is almost equal to the total beta in the reversed-field pinch (RFP). D-alpha emission from recycling deuterium by the plasma-wall interaction decreased during the PPCD. An improved particle confinement time was indicated by a ten fold increase in the ratio of the total number of particles to the D-alpha emission. Single pellet injection into the good particle confinement plasma, achieved by the PPCD, produced high density plasma with high beta values. The plasma electron density rapidly increased to triple that of standard plasma, and high density was maintained till the end of the PPCD period. The electron temperature was lower than that of PPCD without ice pellet injection, but βp remained almost the same because the plasma electron density was higher with pellet injection.
- Published
- 2009
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5. Improved Particle Confinement in Transition from Multiple-Helicity to Quasi-Single-Helicity Regimes of a Reversed-Field Pinch
- Author
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Gianluca Spizzo, Yoichi Hirano, Haruhisa Koguchi, Italo Predebon, Yasuyuki Yagi, Lorenzo Frassinetti, Roscoe White, and Hajime Sakakita
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Physics ,Condensed matter physics ,Reversed field pinch ,General Physics and Astronomy ,Plasma ,reversed field pinch ,Helicity ,Magnetic flux ,transport properties ,Physics::Plasma Physics ,Tearing ,Pinch ,Particle ,Dynamo ,particle orbit and trajectory - Abstract
The quasi-single-helicity (QSH) state of a reversed-field pinch (RFP) plasma is a regime in which the RFP configuration can be sustained by a dynamo produced mainly by a single tearing mode and in which a helical structure with well-defined magnetic flux surfaces arises. In this Letter, we show that spontaneous transitions to the QSH regime enhance the particle confinement. This improvement is originated by the simultaneous and cooperative action of the increase of the magnetic island and the reduction of the magnetic stochasticity.
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- 2006
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6. Deuterium ice pellet injection during pulsed poloidal current drive operation in toroidal pinch Experiment-RX reversed-field pinch device
- Author
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Tomohiko Asai, Kiyoyuki Yambe, Yasuyuki Yagi, David Terranova, Haruhisa Koguchi, Paolo Innocente, Rita Lorenzini, Hajime Sakakita, and Yoichi Hirano
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Electron density ,Toroid ,Materials science ,Physics and Astronomy (miscellaneous) ,Reversed field pinch ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,High density ,Deuterium ,Pellet ,Pinch ,Current (fluid) ,Atomic physics - Abstract
Deuterium ice pellet injection has been used to control the density profile and expand the operation region of a reversed-field pinch (RFP) experiment on a toroidal pinch experiment-RX (TPE-RX) device. With pellet injection during the pulsed poloidal current drive (PPCD) operation, which is one of the good confinement operation conditions in RFP, electron density increases to more than three times that of standard discharge. The pellet is ablated within only approximately 1 ms, nevertheless, this high density can be almost constantly sustained for ~10 ms until completion of the PPCD period. When compared with ordinary discharge without PPCD, particle confinement time increases by a factor of five in the latter part of the PPCD period when the pellet is injected at the start of PPCD discharge.
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- 2006
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7. Quasi-single helicity state at shallow reversal in TPE-RX reversed-field pinch experiment
- Author
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Yasuyuki Yagi, Lorenzo Frassinetti, Satoru Kiyama, Yoichi Hirano, Roberto Paccagnella, H. Koguchi, and H. Sakakita
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Physics ,Toroid ,Reversed field pinch ,Phase (waves) ,Pinch ,Plasma ,Magnetohydrodynamics ,Atomic physics ,Condensed Matter Physics ,Helicity ,Magnetic field - Abstract
The operating conditions for obtaining a quasi-single helicity (QSH) state with a good reproducibility are found in a reversed-field pinch (RFP) experiment on the large RFP machine, TPE-RX [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. In these conditions, the reversal of toroidal magnetic field (Bta) is maintained at a very shallow value (∼−0.2mT) after the setting up phase and the following fast current rising phase. After a certain period at this shallow reversal (∼15–25ms), the m∕n=1∕6 mode (m and n being the poloidal and toroidal Fourier mode numbers, respectively) rapidly grows and saturates before the termination of discharge. The growth of this mode dominates the other modes and the QSH state with m∕n=1∕6 is finally achieved. This QSH state can be sustained for a long period (up to ∼45ms) almost until the end of discharge by applying a delayed reversal of Bta with appropriate trigger timing and magnitude. The initial setup of the QSH states shows a reproducibility of almost 100%, but its susta...
- Published
- 2005
8. Synthetic Study on Acremoxanthone A: Construction of Bicyclo [3.2.2]nonane CD Skeleton and Fusion of AB Rings.
- Author
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Yoichi Hirano, Kensei Tokudome, Hiroshi Takikawa, and Keisuke Suzuki
- Subjects
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XANTHONE , *RING formation (Chemistry) , *NITRILE oxides - Abstract
Toward the total synthesis of acremoxanthone A, a model study has revealed a convergent approach to construct the ABCDE ring system. The key steps include: (1) an effective construction of the bicyclo[ 3.2.2]nonane skeleton, (2) protocol for generating the bridgehead anion and trapping, and (3) 1,3-dipolar cycloaddition of a nitrile oxide to the internal alkene. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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9. Magnetic fluctuation behavior during the transition between quasi-single helicity and multi helicity states in the reversed-field pinch plasma.
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Kiyoyuki Yambe, Hajime Sakakita, Yoichi Hirano, and Haruhisa Koguchi
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PLASMA fluctuations ,MAGNETIC fluids ,REVERSED field pinches ,ELECTROSTATIC actuators ,ELECTRONS - Abstract
We measured the variation of magnetic and electrostatic fluctuations observed during the transition between the quasi-single helicity (QSH) and multi helicity (MH) states in the edge region of the Toroidal Pinch Experiment-Reversed eXperiment reversed-field pinch plasma [Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. The high-frequency magnetic fluctuations largely decrease at the start of the QSH state. During the QSH state, the toroidal and radial magnetic fluctuations slightly increase again between 12 and 18 kHz but the decrease in the poloidal magnetic fluctuation is maintained. The confinement of fast electrons may be improved in the period of the QSH state although the radial magnetic fluctuation increases between 12 and 18 kHz. It is suggested that the improved confinement of fast electrons may be obtained by the decrease in the fast radial magnetic fluctuation having the frequency higher than 20 kHz in the period of the QSH state. Contrarily, the transition from QSH to MH states occurs with the increase in the slow toroidal magnetic fluctuation having the frequency lower than 10 kHz. The QSH state may bring a good confinement of fast electrons by the reduced high-frequency magnetic fluctuation compared with the MH state. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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10. Variation of Magnetic Fluctuation due to Gas Puffing in Edge Region of Reversed-Field Pinch Plasma.
- Author
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Kiyoyuki Yambe, Yoichi Hirano, Hajime Sakakita, and Haruhisa Koguchi
- Abstract
We measured the variation of magnetic and electrostatic fluctuations observed during the gas puffing in the edge region of the toroidal pinch experiment-reversed experiment (TPE-RX) reversed-field pinch plasma. In the short period in which the electron density increased slowly just after the gas puffing, the confinement of fast electrons in the core region was maintained by the decrease in the fast radial magnetic fluctuation with the deepening of the reversal of the toroidal field. During the following period in which the electron density increased rapidly, the radial gradient of electron density decreased, and the loss of fast electrons from the core region increased owing to the increase in the toroidal and radial magnetic fluctuations in the high-frequency band, although the poloidal magnetic fluctuation decreased. Therefore, the confinement of fast electrons would be maintained by keeping the radial gradient of plasma thermal pressure with a moderate neutral particle supply of small quantity in a short time. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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