Search

Your search keyword '"Nishimura, Kotaro"' showing total 102 results
Start Over Author "Nishimura, Kotaro"
102 results on '"Nishimura, Kotaro"'

4. Apparatus for generation of nanojoule-class water-window high-order harmonics

Author

Nishimura, Kotaro, Fu, Yuxi, Suda, Akira, Midorikawa, Katsumi, and Takahashi, Eiji J.

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

In our recent study [Commun. Phys. 3, 92 (2020)], we have developed an approach for energy-scaling of high-order harmonic generation in water-window region under neutral-medium condition. More specifically, we obtained nanojoule-class water-window soft x-ray harmonic beam under phase match condition. It has been achieved by combining a newly developed terawatt-class mid-infrared femtosecond laser and a loose focusing geometry for high-order harmonic generation. The generated beam is more than 100 times intense compared to previously reported results. The experimental setup included two key parts: terawatt mid-infrared femtosecond driving laser [ Sci. Rep. 8, 7692 (2018)] and specially designed gas cell. Despite the dramatic drop in the optimal gas pressure due to loose focusing geometry, it still reached 1 bar level for helium. Moreover, faster leaking speed caused by larger pinhole size of the gas cell made the use of a normal gas cell impossible. Thus, we have designed a double-structured pulsed-gas cell with a differential pumping system, which enabled providing sufficiently high gas pressure. Moreover, it allowed reducing gas consumption significantly. Robust energy-scalable apparatus for high-order harmonic generation developed in in this study will enable the generation of over tens nanojoule water-window attosecond pulses in the nearest future., Comment: 10 pages, 8 figures

Published
2020
Full Text
View/download PDF

5. Energy scaling of water window high-order harmonic generation for single-shot soft X-ray spectroscopy and live-cell imaging

Author

Fu, Yuxi, Nishimura, Kotaro, Shao, Renzhi, Suda, Akira, Midorikawa, Katsumi, Lan, Pengfei, and Takahashi, Eiji J.

Subjects
Physics - Optics
Abstract

Full coherent soft X-ray attosecond pulses are now available through high-order harmonic generation (HHG); however, its insufficient output energy hinders various applications, such as attosecond-scale soft X-ray nonlinear experiments, the seeding of soft X-ray free-electron lasers, attosecond-pump-attosecond-probe spectroscopies, and single-shot imaging. In this paper, towards the implementation of these exciting studies, we demonstrate a soft X-ray harmonic beam that is more than two orders of magnitudes stronger up to the water window region compared to previous works. This was achieved by combining a newly developed TW class mid-infrared femtosecond laser and a loosely focusing geometry for HHG in the mid-infrared region for the first time. Thanks to a loosely focusing geometry with a neutral medium target, we achieve a high conversion efficiency, a low beam divergence, and a significantly reduced medium gas pressure. As the first application of our nano-joule level water window soft X-ray harmonic source, we demonstrate near edge X-ray absorption fine structure (NEXAFS) experiments with clear fine absorption spectra near the K- and L-edges observed in various samples. The systematic study of a robust energy scaling method on HHG opens the door for demonstrating single-shot absorption spectrum and live cell imaging with a femtosecond time resolution., Comment: 9 pages, 7 figures

Published
2020
Full Text
View/download PDF

6. Optimization of a multi-TW few-cycle 1.7-$\mu$m source based on Type-I BBO dual-chirped optical parametric amplification

Author

Xu, Lu, Nishimura, Kotaro, Fu, Yuxi, Suda, Akira, Midorikawa, Katsumi, and Takahashi, Eiji J.

Subjects
Physics - Optics
Abstract

This paper presents the optimization of a dual-chirped optical parametric amplification (DC-OPA) scheme for producing an ultrafast intense infrared (IR) pulse. By employing a total energy of 0.77 J Ti:sapphire pump laser and type-I BBO crystals, an IR pulse energy at the center wavelength of 1.7 $\mu$m exceeded 0.1 J using the optimized DC-OPA. By adjusting the injected seed spectrum and prism pair compressor with a gross throughput of over 70 \%, the 1.7-$\mu$m pulse was compressed to 31 fs, which resulted in a peak power of up to 2.3 TW. Based on the demonstration of the BBO type-I DC-OPA, we propose a novel OPA scheme called the $dual~pump$ DC-OPA for producing a high-energy IR pulse with a two-cycle duration., Comment: 9 pages, 7 figures

Published
2020
Full Text
View/download PDF

9. Extracellular vesicles containing fullerene derivatives prepared by an exchange reaction for photodynamic therapy.

Author

Kono, Nanami, Kawasaki, Riku, Oshige, Ayano, Nishimura, Kotaro, Yamana, Keita, Yimiti, Dilimulati, Miyaki, Shigeru, Adachi, Nobuo, Takabayashi, Naoki, Nagasaki, Takeshi, and Ikeda, Atsushi

Abstract

Extracellular vesicles (EVs) have excellent biocompatibility and long retention times in the circulation and have consequently been expected to be useful as drug-delivery systems. However, their applications have been limited because of the inability to introduce hydrophobic compounds to EVs without the use of harmful organic solvents. Herein, we developed an organic-solvent-free drug-loading technique based on the host exchange reaction. We demonstrated that the exchange reaction enabled quantitative loading of EVs with highly concentrated (0.1 mM) hydrophobic fullerene derivatives. Fullerene derivative–loaded EVs (EVs/C60) could eliminate cancer cell lines more efficiently than fullerene derivative-loaded liposomes (Lip/C60). Moreover, the photodynamic activity of EVs/C60 was fivefold higher than that of the clinically available photosensitizer photofrin. EVs/C60 could efficiently suppress tumor growth in tumor-xenograft model mice. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

11. HER‐2‐Targeted Boron Neutron Capture Therapy with Carborane‐integrated Immunoliposomes Prepared via an Exchanging Reaction

Author

Kawasaki, Riku, primary, Oshige, Ayano, additional, Yamana, Keita, additional, Hirano, Hidetoshi, additional, Nishimura, Kotaro, additional, Miura, Yamato, additional, Yorioka, Ryuji, additional, Sanada, Yu, additional, Bando, Kaori, additional, Tabata, Anri, additional, Yasuhara, Kazuma, additional, Miyazaki, Yusuke, additional, Shinoda, Wataru, additional, Nishimura, Tomoki, additional, Azuma, Hideki, additional, Takata, Takushi, additional, Sakurai, Yoshinori, additional, Tanaka, Hiroki, additional, Suzuki, Minoru, additional, Nagasaki, Takeshi, additional, and Ikeda, Atsushi, additional

Published
2023
Full Text
View/download PDF

15. Phospholipid‐Coated Boronic Oxide Nanoparticles as a Boron Agent for Boron Neutron Capture Therapy

Author

Kawasaki, Riku, primary, Hirano, Hidetoshi, additional, Yamana, Keita, additional, Oshige, Ayano, additional, Nishimura, Kotaro, additional, Kono, Nanami, additional, Sanada, Yu, additional, Bando, Kaori, additional, Tabata, Anri, additional, Yasukawa, Naoki, additional, Azuma, Hideki, additional, Takata, Takushi, additional, Sakurai, Yoshinori, additional, Tanaka, Hiroki, additional, Suzuki, Minoru, additional, Tarutani, Naoki, additional, Katagiri, Kiyofumi, additional, Nagasaki, Takeshi, additional, and Ikeda, Atsushi, additional

Published
2023
Full Text
View/download PDF

19. High-energy mid-infrared femtosecond pulses at 3.3 μm directly generated by dual-chirped optical parametric amplification

Author

Fu Yuxi, Nishimura Kotaro, Xue Bing, Suda Akira, Midorikawa Katsumi, and Eiji J. Takahashi

Subjects
Physics, QC1-999
Abstract

By employing a dual-chirped optical parametric amplification (DC-OPA) using MgO:LiNbO3 crystals, we generate 31 mJ mid-infrared (MIR) pulses at 3.3 um with a repetition rate of 10 Hz. After passing through a CaF2 bulk compressor which has 70% throughput efficiency, these MIR pulses are compressed to 70 fs (6.3 optical cycles), which is close to the transform-limited duration of 66 fs. Thus, the peak power is evaluated to be 0.3 TW. Our results present notable progress in the generation of high-energy MIR pulses and prove that DC-OPA is a superior method for efficiently generating MIR pulses with few-cycle duration and TW-class peak power.

Published
2019
Full Text
View/download PDF

24. Cooperative visuomotor learning experience with peer enhances\ud adaptability to others

Author

Nishimura, Kotaro, Saracbasi, Ozge Ozlem, Hayashi, Yoshikatsu, and Kondo, Toshiyuki

Abstract

Skilled musicians can improvise with first-time partners. Thus, the question arises how the adaptability\ud to others can emerge through the mutual motor learning experience.We developed a two-person\ud cooperative visuomotor task; an object was connected through virtual springs with the cursors controlled\ud by the subjects. We instructed paired subjects to jointly control the object toward a specified\ud target under a virtual force field. Experimental results suggest that a novice subject who was trained\ud with a skill-level matched peer in the Learning phase showed significantly better adaptability to others\ud in the successive Evaluation phase. Variety of the cooperative experience with others in the visuomotor\ud task probably gave rise to high adaptability in the novice-to-novice group subjects, while the learning\ud experience with an expert did not. We conclude that the motor skills acquired during mutual interactions\ud with peers can lead to have an ability to tune the motor commands subject to the dynamics\ud of the external environment and the behavior of the partners.

Published
2021

42. Leukemogenesis induced by c-terminal mutations in the basic leucine zipper domain of C/EBPα

Author

Togami, Katsuhiro, primary, Kitaura, Jiro, additional, Inoue, Daichi, additional, Kagiyama, Yuki, additional, Uchida, Tomoyuki, additional, Nishimura, Kotaro, additional, Doki, Noriko, additional, Kato, Naoko, additional, Nakahara, Fumio, additional, Oki, Toshihiko, additional, Harada, Yuka, additional, Harada, Hironori, additional, and Kitamura, Toshio, additional

Published
2013
Full Text
View/download PDF

43. Method to improve straightness and remove torsion of uncoiled wires.

Author

Nishimura, Kotaro, Asakawa, Motoo, Kitazawa, Masaki, and Yokoyama, Akihisa

Subjects
WIRE, TORSION, STRAINS & stresses (Mechanics), DEFORMATIONS (Mechanics), ELASTICITY
Abstract

The article presents a research study concerning the methods in torsion removal and straightness improvement of uncoiled industrial wires placed in drums. Study shows that wires that are placed in drums can be deformed due to stresses such as twisting and bending. In addition, there is a meager deformation of wires when placed in large drums, Moreover, wire twisting before placing it in drum is also suggested.

Published
2011

44. Synthetic Studies of Cobalt Carbonyl by Noble Metal Catalysts. I. The Effects of the Form of Cobalt Feed and Noble Metal Catalysts

Author

Usami, Seiji, Kondo, Takayoshi, Nishimura, Kotaro, and Koga, Yuzo

Abstract

A novel method of synthesizing cobalt carbonyl was investigated by using noble metal catalysts. It has been observed that the materials containing palladium, i. e., palladium black, palladium chloride, palladium acetylacetonate, bistriphenylphosphine dichloropalladium, and palladium-on-carriers, have a catalytic effect on the cobalt carbonylation reaction, and that palladium-on-carbon (Pd-C) is the most active catalyst. The reactivity of cobalt compounds in the cobalt carbonylation reaction catalyzed by noble metals increases in this order: CoSO4<Au>Pt>>Ag. The effect of the catalyst concentration and the activity of noble-metal catalysts were also compared with those in the case of dicobalt octacarbonyl, as an autocatalyst.

Published
1969
Full Text
View/download PDF

45. Synthetic Studies of Cobalt Carbonyl by Noble Metal Catalysts. II. The Investigation of Reaction Conditions

Author

Usami, Seiji, Nishimura, Kotaro, Koyama, Takeo, and Fukushi, Saburo

Abstract

The reaction conditions of cobalt carbonylation catalyzed by palladium have been investigated. Polar solvents have, with some exceptions, been shown to be superior to nonpolar solvents. The fact that the total pressure of synthesis gas and the partial pressure of hydrogen, especially the latter, have a great effect on the initiation temperature of reaction suggests that the presence of hydrogen is very important in the present reaction. The low reactivity and poor yield in the reactions of Raney cobalt indicate that a low-valency intermediate in the course of the cobalt-carbonylation reaction of cobaltous compounds may be somewhat different from the Raney-type Co(0). The initial step of the reaction seems to be affected only a little by various additives e. g., water, triphenyl phosphine, lead naphthenate, and sodium hydroxide. The data previously available suggest that a palladium catalyst may primarily promote the reduction of Co (II) to Co(0) by activating hydrogen. The test of the lifetime of a palladium-on-carbon catalyst for a month indicates that there is no apparent decrease in the catalytic activity within this period.

Published
1969
Full Text
View/download PDF

50. HER-2-Targeted Boron Neutron Capture Therapy with Carborane-integrated Immunoliposomes Prepared via an Exchanging Reaction.

Author

Kawasaki R, Oshige A, Yamana K, Hirano H, Nishimura K, Miura Y, Yorioka R, Sanada Y, Bando K, Tabata A, Yasuhara K, Miyazaki Y, Shinoda W, Nishimura T, Azuma H, Takata T, Sakurai Y, Tanaka H, Suzuki M, Nagasaki T, and Ikeda A

Subjects
Humans, Liposomes, Boron, Boron Compounds, Fructose, Boron Neutron Capture Therapy methods, Boranes
Abstract

Boron neutron capture therapy (BNCT) is a promising modality for cancer treatment because of its minimal invasiveness. To maximize the therapeutic benefits of BNCT, the development of efficient platforms for the delivery of boron agents is indispensable. Here, carborane-integrated immunoliposomes were prepared via an exchanging reaction to achieve HER-2-targeted BNCT. The conjugation of an anti-HER-2 antibody to carborane-integrated liposomes successfully endowed these liposomes with targeting properties toward HER-2-overexpressing human ovarian cancer cells (SK-OV3); the resulting BNCT activity toward SK-OV3 cells obtained using the current immunoliposomal system was 14-fold that of the l-BPA/fructose complex, which is a clinically available boron agent. Moreover, the growth of spheroids treated with this system followed by thermal neutron irradiation was significantly suppressed compared with treatment with the l-BPA/fructose complex., (© 2023 Wiley-VCH GmbH.)

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results