Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Temperature of thermal spikes in amorphous silicon nitride films produced by 1.11 MeV C impacts

Kitayama, Takumi*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Matsuda, Makoto; Sataka, Masao*; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 354, p.183 - 186, 2015/07

https://doi.org/10.1016/j.nimb.2014.11.002

Frustration-induced magnetic properties of the spin-1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice

Isoda, Makoto*; Nakano, Hiroki*; Sakai, Toru

Journal of the Physical Society of Japan, 83(8), p.084710_1 - 084710_7, 2014/08

https://doi.org/10.7566/JPSJ.83.084710

The spin-1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice is investigated by the numerical diagonalization. As a result, it was found that an orthogonal dimer, the disorder, and the ferrimagnetic states appear depending on the ratio of the two exchange interactions.

Magnetization process of the = 1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice

Nakano, Hiroki*; Isoda, Makoto*; Sakai, Toru

Journal of the Physical Society of Japan, 83(5), p.053702_1 - 053702_4, 2014/04

https://doi.org/10.7566/JPSJ.83.053702

We study the = 1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice by the numerical diagonalization. We tune the ratio of two antiferromagnetic interactions coming from two kinds of in equivalent sites in this lattice, examining the magnetization process; particular attention are focused on the one-third height of the saturation. We find that a quantum phase transition occurs at a specific value of the ratio and that a magnetization plateau appears in the vicinity of the transition.

Quantitative analysis of cisplatin sensitivity of human esophageal squamous cancer cell lines using in-air micro-PIXE

Tanaka, Naritake*; Kimura, Hitoshi*; Faried, A.*; Sakai, Makoto*; Sano, Takaaki*; Inose, Takanori*; Soda, Makoto*; Okada, Koji*; Nakajima, Masanobu*; Miyazaki, Tatsuya*; et al.

Cancer Science, 101(6), p.1487 - 1492, 2010/06

https://doi.org/10.1111/j.1349-7006.2010.01542.x

We examined the intracellular localization of cisplatin, a key chemotherapeutic agent, in esophageal cancer cell lines and determined their sensitivity to cisplatin using in-air micro-PIXE. Two human esophageal squamous cell carcinoma (ESCC) cell lines, TE-2 and TE-13, were examined for their response to cisplatin using MTT assay, flow cytometry and DNA fragmentation assays. Real-time reverse transcription-polymerase chain reaction was also used to evaluate the mRNA expression of multidrug resistance protein 2 (MRP2) in both cell lines. Platinum localizations of intracellular and intranuclear were measured using in-air micro-PIXE. TE-2 cells were more sensitive to cisplatin than TE-13 cells. The results of this study suggest that in-air micro-PIXE could be a useful quantitative method for evaluating the cisplatin sensitivity of individual cells. Finally, we speculate that MRP2 in the cell membrane may play an important role in regulating cisplatin sensitivity of ESCC cells.

Intense femto-second laser-driven X-ray source coupled with multiple directional quantum beams for applications

Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Yogo, Akifumi; Mori, Michiaki; Li, Z.*; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

X-Ray Lasers 2006; Springer Proceedings in Physics, Vol.115, p.595 - 605, 2007/00

At present, using ultra-short high intensity lasers at APRC, JAEA Kansai photon research institute, we are developing laser driven multiple quantum beams such as protons, X-rays, electrons and THz waves. These beams are perfectly synchronized with each other. The pulse duration of each beam is lass than a pico-second. They have sharp directionality with high brightness. If we properly combined these, we have new pump-probe techniques for various applications.

Simultaneous generation of proton beam and terahertz radiation under intense ultrashort pulse-laser irradiation

Sagisaka, Akito; Daido, Hiroyuki; Pirozhkov, A. S.; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Yogo, Akifumi; Nakamura, Shu*; Iwashita, Yoshihisa*; Shirai, Toshiyuki*; et al.

no journal, , 

no abstracts in English

Generation of high-energy proton and electromagnetic waves with a high-intensity laser

Sagisaka, Akito; Daido, Hiroyuki; Pirozhkov, A. S.; Ma, J.-L.; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Nishiuchi, Mamiko; Kawachi, Tetsuya; et al.

no journal, , 

High-intensity laser and thin-foil interactions produce high energy ions, electrons, X-ray, high-order harmonics, and THz radiation. High-energy protons driven by the high-intensity laser is paid attention as a compact ion source for medical application. The simultaneous generation of the protons and THz or harmonics will provide us high-density plasma diagnostic or unique pump-probe techniques. We use a Ti:sapphire laser system (JLITE-X) in JAEA for THz radiation. The laser beam is focused by an off-axis parabolic mirror at the 5 m thick Ti target. We observe simultaneously both the high-energy proton and THz radiation by changing the duration of ASE preceding the main pulse. We use a Ti:sapphire laser system in CRIEPI for harmonic generation. The laser beam is focused by an off-axis parabolic mirror at the 7.5 m thick polyimide target surface. The high-energy protons and UV harmonics are observed at the target is moved away from the best focus.

Evaluation of cisplatin localization in a cell and evaluation of sensitivity of esophageal cancer cell line

Tanaka, Naritake*; Sakai, Makoto*; Kimura, Hitoshi*; Soda, Makoto*; Nakajima, Masanobu*; Kato, Hiroyuki*; Asao, Takayuki*; Kuwano, Hiroyuki*; Oikawa, Masakazu*; Sato, Takahiro; et al.

no journal, , 

no abstracts in English

Magnetization ramp and XXZ anisotropy of kagome lattice antiferromagnets

Sakai, Toru; Nakano, Hiroki*; Isoda, Makoto*; Okunishi, Koichi*

no journal, , 

The previous study indicated that a magnetization plateau-like behavior at 1/3 of saturation magnetization is a new phenomena, so-called a magnetization ramp. In the present work we investigate a change of the anomalous behavior under the XXZ anisotropy. As a result, we found that as the XXZ anisotropy is varied from the Ising and XY sides, the magnetization plateau vanishes at a critical point.