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49 results on '"Hirai, Shota"'

3. Status of geospace x-ray imager mission (GEO-X)

Author

den Herder, Jan-Willem A., Nikzad, Shouleh, Nakazawa, Kazuhiro, Ezoe, Yuichiro, Funase, Ryu, Nagata, Harunori, Miyoshi, Yoshizumi, Nakajima, Hiroshi, Mitsuishi, Ikuyuki, Ishikawa, Kumi, Numazawa, Masaki, Sato, Yuki, Kawabata, Yosuke, Fuse, Ryota, Nakajima, Shintaro, Boden, Ralf, Kamps, Landon, Nobuhara, Yuki, Hirai, Shota, Yoneyama, Tomokage, Hagino, Kouichi, Matsumoto, Yosuke, Hosokawa, Keisuke, Kasahara, Satoshi, Ishi, Daiki, Hiraga, Junko, Mitsuda, Kazuhisa, Fujimoto, Masaki, Ueno, Munetaka, Yamazaki, Atsushi, Hasegawa, Hiroshi, Mitani, Takefumi, Kawakatsu, Yasuhiro, Iwata, Takahiro, Koizumi, Hiroyuki, Sahara, Hironori, Kanamori, Yoshiaki, and Morishita, Kohei

Published
2024
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4. GEOspace X-ray imager (GEO-X)

Author

Ezoe, Yuichiro, primary, Funase, Ryu, additional, Nagata, Harunori, additional, Miyoshi, Yoshizumi, additional, Nakajima, Hiroshi, additional, Mitsuishi, Ikuyuki, additional, Ishikawa, Kumi, additional, Numazawa, Masaki, additional, Kawabata, Yosuke, additional, Nakajima, Shintaro, additional, Fuse, Ryota, additional, Boden, Ralf C., additional, Kamps, Landon, additional, Yoneyama, Tomokage, additional, Hagino, Kouichi, additional, Matsumoto, Yosuke, additional, Hosokawa, Keisuke, additional, Kasahara, Satoshi, additional, Hiraga, Junko, additional, Mitsuda, Kazuhisa, additional, Fujimoto, Masaki, additional, Ueno, Munetaka, additional, Yamazaki, Atsushi, additional, Hasegawa, Hiroshi, additional, Mitani, Takefumi, additional, Kawakatsu, Yasuhiro, additional, Iwata, Takahiro, additional, Koizumi, Hiroyuki, additional, Sahara, Hironori, additional, Kanamori, Yoshiaki, additional, Morishita, Kohei, additional, Ishi, Daiki, additional, Fukushima, Aoto, additional, Inagaki, Ayata, additional, Ueda, Yoko, additional, Morishita, Hiromi, additional, Tsuji, Yukine, additional, Sekiguchi, Runa, additional, Murakawa, Takatoshi, additional, Yamaguchi, Kazuma, additional, Ishikawa, Rei, additional, Morimoto, Daiki, additional, Yamada, Yudai, additional, Hirai, Shota, additional, Nobuhara, Yuki, additional, Leung, Yownin Albert M., additional, Itoigawa, Yamato, additional, Onodera, Ryo, additional, Kotaki, Satoru, additional, Nakamura, Shotaro, additional, Kiuchi, Ayumi, additional, Matsumoto, Takuya, additional, Hirota, Midori, additional, and Kashiwakura, Kazuto, additional

Published
2023
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10. Excited Carrier Dynamics in a Dye-Sensitized Niobate Nanosheet Photocatalyst for Visible-Light Hydrogen Evolution

Author

Nishioka, Shunta, Oshima, Takayoshi, Hirai, Shota, Saito, Daiki, Hojo, Koya, Mallouk, Thomas E., and Maeda, Kazuhiko

Subjects
Materials science, 010405 organic chemistry, General Chemistry, 010402 general chemistry, Photochemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Excited state, Photocatalysis, Surface modification, Hydrogen evolution, Carrier dynamics, Visible spectrum, Nanosheet
Abstract

Dye-sensitized photocatalysts that consist of a light-absorbing dye and a wide-gap oxide semiconductor have been studied extensively as components of solar energy conversion systems. Although surfa...

Published
2020

11. 観測ロケットS-520を用いた宇宙環境下でのハイブリッドキックモータ実験の提案

Author

KAMPS, Landon, HIRAI, Shota, and NAGATA, Harunori

Abstract

第4回観測ロケットシンポジウム（2022年3月14-15日. ハイブリッド開催（JAXA相模原キャンパス& オンライン）), 4th Sounding Rocket Symposium(March 14-15, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000175012, レポート番号: Ⅱ-7

Published
2022

14. Protective Effect of Antioxidative Liposomes Co-encapsulating Astaxanthin and Capsaicin on CCl4-Induced Liver Injury

Author

Fukuta, Tatsuya, Hirai, Shota, Yoshida, Tatsusada, Maoka, Takashi, and Kogure, Kentaro

Subjects
astaxanthin, antioxidant, liposome, stereochemistry, intermolecular interaction, capsaicin
Abstract

Our previous study reported that co-encapsulation of potent antioxidants astaxanthin (Asx) and capsaisin (Cap) into liposomes brought about synergistically higher antioxidative activity than the calculated additive activity of each single antioxidant encapsulating liposome. Based on the previous computational chemistry analysis, the synergistic effect was revealed to be resulted from intermolecular interactions between Asx, especially 3R,3′R-form of Asx stereoisomer (Asx-R), and Cap, by which changes of electronic states of the polyene moiety of Asx-R were induced. Although liposomes co-encapsulating Asx-R and Cap (Asx-R/Cap-Lipo) at an optimal ratio clearly showed synergistic antioxidative activity in vitro, it is unclear whether the effective antioxidative activity derived from intermolecular interaction between Asx-R and Cap is also exerted in vivo. Therefore, in this study, we investigated therapeutic potential of Asx-R/Cap-Lipo as an antioxidant formulation in vivo. For this purpose, we employed carbon tetrachloride (CCl4)-induced acute liver injury rat model, since CCl4 is known to cause oxidative damage in liver. CCl4 administration significantly increased the levels of aspartate transaminase (AST) and alanine aminotransferase (ALT). Intravenous combined administration of liposomes encapsulating Asx-R (Asx-R-Lipo) and liposomes encapsulating Cap (Cap-Lipo) significantly decreased CCl4-induced increase of AST and ALT levels. Importantly, the treatment with Asx-R/Cap-Lipo tended to show higher protective effect on acute liver injury than combined treatment with Asx-R-Lipo plus Cap-Lipo. These results suggest that co-encapsulated Asx-R and Cap in liposomal membranes could exert more effective antioxidative activities in vivo, and that Asx-R/Cap-Lipo would be a hopeful antioxidant formulation for treating reactive oxygen species-related diseases.

Published
2020

18. Hybrid Rockets as Post-Boost Stages and Kick Motors

Author

Kamps, Landon, Hirai, Shota, 1000040281787, Nagata, Harunori, Kamps, Landon, Hirai, Shota, 1000040281787, and Nagata, Harunori

Abstract

Hybrid rockets are attractive as post-boost stages and kick motors due to their inherent safety and low cost, but it is not clear from previous research which oxidizer is most suitable for maximizing Delta V within a fixed envelope size, or what impact O/F shift and nozzle erosion will have on Delta V. A standard hybrid rocket design is proposed and used to clarify the impact of component masses on Delta V within three 1 m(3) envelopes of varying height-to-base ratios. Theoretical maximum Delta V are evaluated first, assuming constant O/F and no nozzle erosion. Of the four common liquid oxidizers: H2O2 85 wt%, N2O, N2O4, and LOX, H2O2 85 wt% is shown to result in the highest Delta V, and N2O is shown to result in the highest density Delta V, which is the Delta V normalized for motor density. When O/F shift is considered, the Delta V decreases by 9% for the N2O motor and 12% for the H2O2 85 wt% motor. When nozzle erosion is also considered, the Delta V decreases by another 7% for the H2O2 85 wt% motor and 4% for the N2O motor. Even with O/F shift and nozzle erosion, the H2O2 85 wt% motor can accelerate itself (916 kg) upwards of 4000 m/s, and the N2O motor (456 kg) 3550 m/s.

Published
2021

21. Investigation of Graphite Nozzle Erosion in Hybrid Rockets Using Oxygen/High-Density Polyethylene

Author

Kamps, Landon, Hirai, Shota, Sakurai, Kazuhito, Viscor, Tor, Saito, Yuji, Guan, Raymond, Isochi, Hikaru, Adachi, Naoto, Itoh, Mitsunori, 1000040281787, Nagata, Harunori, Kamps, Landon, Hirai, Shota, Sakurai, Kazuhito, Viscor, Tor, Saito, Yuji, Guan, Raymond, Isochi, Hikaru, Adachi, Naoto, Itoh, Mitsunori, 1000040281787, and Nagata, Harunori

Abstract

A recently developed reconstruction technique is used to investigate graphite nozzle erosion in two scales of hybrid rocket motors, 30-N-thrust class and 2000-N-thrust class, using oxygen as the oxidizer and high-density polyethylene as the fuel. Thermocouple measurements taken from within the nozzles are used to estimate nozzle throat wall temperature. Forty-four static firing tests were conducted under varying experimental conditions to confirm the validity of the reconstruction technique results, to investigate the conditions at the onset of erosion, and to formulate an empirical predictive model of nozzle erosion rate. Results show that a single formula that treats the combustion gas as a single oxidizing agent for which heterogenous rate constants are functions of equivalence ratio can satisfactorily replicate the erosion rate of graphite by a combustion gas containing multiple oxidizing species. Furthermore, the chemical-kinetic-limited conditions of the onset of nozzle erosion are specified by a novel empirical correlation, which shows that erosion begins at lower temperature and pressure in oxidizer-rich combustion gas than in fuel-rich combustion gas.

Published
2020

28. An Artificial Z-Scheme Constructed from Dye-Sensitized Metal Oxide Nanosheets for Visible Light-Driven Overall Water Splitting

Author

Oshima, Takayoshi, primary, Nishioka, Shunta, additional, Kikuchi, Yuka, additional, Hirai, Shota, additional, Yanagisawa, Kei-ichi, additional, Eguchi, Miharu, additional, Miseki, Yugo, additional, Yokoi, Toshiyuki, additional, Yui, Tatsuto, additional, Kimoto, Koji, additional, Sayama, Kazuhiro, additional, Ishitani, Osamu, additional, Mallouk, Thomas E., additional, and Maeda, Kazuhiko, additional

Published
2020
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33. Enhancement of antioxidative activity of astaxanthin by combination with an antioxidant capable of forming intermolecular interactions

Author

Fukuta, Tatsuya, Hirai, Shota, Yoshida, Tatsusada, Maoka, Takashi, Kogure, Kentaro, Fukuta, Tatsuya, Hirai, Shota, Yoshida, Tatsusada, Maoka, Takashi, and Kogure, Kentaro

Abstract

We previously demonstrated that co-encapsulation of the potent antioxidant astaxanthin (Asx) and tocotrienols into liposomes results in synergistically higher antioxidative activity than the calculated additive activity of each individual antioxidant-containing liposome, due to intermolecular interactions between terminal ring moieties of the two antioxidants and the polyene chain and the triene moiety. We reported that intermolecular interactions depend on the stereochemistry of Asx, and change the electronic state of the Asx polyene moiety. Based on these findings, we hypothesized that antioxidants that interact with Asx at the terminal ring and polyene moieties may enhance the antioxidative activity. Herein, we selected two candidate antioxidants, capsaicin (Cap) and resveratrol, based on their structures, in which the compounds exhibit similar characteristics to tocotrienols. We evaluated the antioxidative capacities of liposomes co-encapsulating Asx and the selected candidates. Based on hydroxyl radical scavenging activity, Cap was found to synergistically enhance the antioxidative activity of Asx at an optimal Asx/Cap ratio. Intermolecular interactions between Asx and Cap are necessary for the synergistic effect, and the Asx stereoisomer 3R,3’R-form (Asx-R) was predicted to most potently interact. Liposomes co-encapsulating Asx-R and Cap exhibited clear synergistic antioxidative activity at an optimal ratio, whereas liposomes co-encapsulating the other Asx stereoisomer and Cap did not demonstrate such activity. Computational chemistry analysis showed that changes in the electronic state of the polyene moiety of Asx-R are crucial for the synergistic activity. These results suggest that antioxidants that can change the electronic state of Asx via intermolecular interactions may enhance the function of Asx.

Published
2019

49. Protective Effect of Antioxidative Liposomes Co-encapsulating Astaxanthin and Capsaicin on CCl 4 -Induced Liver Injury.

Author

Fukuta T, Hirai S, Yoshida T, Maoka T, and Kogure K

Subjects
Acute Disease, Animals, Capsaicin chemistry, Capsaicin pharmacology, Carbon Tetrachloride, Liposomes, Male, Rats, Rats, Wistar, Xanthophylls administration & dosage, Xanthophylls chemistry, Xanthophylls pharmacology, Antioxidants pharmacology, Capsaicin administration & dosage, Chemical and Drug Induced Liver Injury prevention & control
Abstract

Our previous study reported that co-encapsulation of potent antioxidants astaxanthin (Asx) and capsaisin (Cap) into liposomes brought about synergistically higher antioxidative activity than the calculated additive activity of each single antioxidant encapsulating liposome. Based on the previous computational chemistry analysis, the synergistic effect was revealed to be resulted from intermolecular interactions between Asx, especially 3R,3'R-form of Asx stereoisomer (Asx-R), and Cap, by which changes of electronic states of the polyene moiety of Asx-R were induced. Although liposomes co-encapsulating Asx-R and Cap (Asx-R/Cap-Lipo) at an optimal ratio clearly showed synergistic antioxidative activity in vitro, it is unclear whether the effective antioxidative activity derived from intermolecular interaction between Asx-R and Cap is also exerted in vivo. Therefore, in this study, we investigated therapeutic potential of Asx-R/Cap-Lipo as an antioxidant formulation in vivo. For this purpose, we employed carbon tetrachloride (CCl 4 )-induced acute liver injury rat model, since CCl 4 is known to cause oxidative damage in liver. CCl 4 administration significantly increased the levels of aspartate transaminase (AST) and alanine aminotransferase (ALT). Intravenous combined administration of liposomes encapsulating Asx-R (Asx-R-Lipo) and liposomes encapsulating Cap (Cap-Lipo) significantly decreased CCl 4 -induced increase of AST and ALT levels. Importantly, the treatment with Asx-R/Cap-Lipo tended to show higher protective effect on acute liver injury than combined treatment with Asx-R-Lipo plus Cap-Lipo. These results suggest that co-encapsulated Asx-R and Cap in liposomal membranes could exert more effective antioxidative activities in vivo, and that Asx-R/Cap-Lipo would be a hopeful antioxidant formulation for treating reactive oxygen species-related diseases.

Published
2020
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