Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Wada, Ayaka*; Miura, Tsutomu*; Cheong, Chikako*; Osawa, Takahito
Bunseki Kagaku, 75(6), p.353 - 358, 2026/06
In this study, prompt gamma-ray analysis (PGA) was applied to determine hydrogen in low-melting-point metals. NIST SRM 2454a (Hydrogen in Titanium Alloy) was used as the calibration standard, and six metals bismuth, lead, gallium, tellurium, tin, and zinc were examined. Hydrogen was successfully quantified in bismuth and lead, and measurement uncertainties were evaluated. The hydrogen mass fractions were 7.1 mg/kg for bismuth and 4.9 mg/kg for lead. In contrast, quantitative determination for the remaining metals was not feasible due to high background levels or interfering peaks; therefore, hydrogen contents were assessed as detection limits. This study demonstrates that PGA is an effective method for hydrogen analysis in low-melting-point metals, for which conventional inert gas fusion-based techniques are inadequate. The findings provide SI-traceable fundamental data that can contribute to advanced characterization of materials, such as performance evaluation of hydrogen-processed products and improvement of hydrogen storage materials.
Kimura, Rintaro*; Sumita, Takehiro*; Osawa, Takahito; Matsuno, Kota*; Nakashima, Kunihiko*; Saito, Noritaka*
ISIJ International, 66(7), p.814 - 820, 2026/06
Times Cited Count：0 Percentile：0.00(Metallurgy & Metallurgical Engineering)The new system developed in this study overcomes this technical difficulty by employing LabVIEW, which is a graphical programming environment for measurement and control. The system allows us to control the temperature with high precision and a high degree of freedom. This device can be fabricated using only basic engineering knowledge by simplifying the electrical circuits of conventional hot-thermocouple devices. Test measurements demonstrated the reliability of temperature measurement using the developed system as well as its promising potential for temperature control of samples with complex patterns (e.g., sinusoidal wave with an amplitude of 50
C and a period of 1 s). Furthermore, the production of a time-temperature-transformation diagram of the CaO-SiO
-LiO system was demonstrated by 
observations of the sample melt using the developed system. By combining with image analysis, the timing of crystallization was determined quantitatively and mechanically, thus successfully eliminating the uncertainty caused by human analysis.
Chiu, I.-H.; Osawa, Takahito
Hamon, 36(2), p.80 - 83, 2026/05
Kokubu, Yoko; Osawa, Takahito; Ozawa, Tatsuhiko; Abe, Kazuhide
Dai-25-Kai AMS Shimpojiumu Hokokushu (Internet), 2 Pages, 2026/01
no abstracts in English
Rooks, J. R.*; Ferraro, G.*; Fratini, E.*; Osti, N. C.*; Osawa, Takahito; Faraone, A.*; Wagner, N. J.*
Physical Review E, 113(1), p.015405_1 - 015405_7, 2026/01
Times Cited Count：1 Percentile：82.94(Physics, Fluids & Plasmas)Segmental dynamics of polymer chains in a model nanocomposite of poly(ethylene oxide) and silica nanoparticles (NPs) was investigated using quasi-elastic neutron scattering. Both these dynamics can be accurately described with the Rouse model. The bulk-like polymer far from the NP surface behaves as the neat polymer. However, the slower polymer in the interface close to the NP surface is described either with a second Rouse population with different relaxation time or using the suppressed Rouse model. These simple two-population models accurately reproduce the experimental data, with the suppressed Rouse model describing topological constraints on average every 12 beads with an interfacial thickness up to 13.5 beads, and the effect of the interface extending to a layer of thickness comparable to the end-to-end distance of the polymer.
Kimura, Rintaro*; Sumita, Takehiro*; Osawa, Takahito; Matsuno, Kota*; Nakashima, Kunihiko*; Saito, Noritaka*
Tetsu To Hagane, 111(15), p.955 - 962, 2025/11
Times Cited Count：0This study developed a new system to address the maintenance challenges of conventional high-temperature thermocouple techniques. Utilizing LabVIEW, the system simplifies complex circuitry, allowing for high-precision and flexible temperature control with basic technical knowledge. Testing confirmed its reliability and ability to control complex temperature patterns. The system successfully created a TTT diagram for a specific material, and image analysis enabled objective, quantitative determination of crystallization timing. This new system offers a significant advancement in high-temperature observation and control.
Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Takahashi, Tadayuki*
Medical Physics, 52(10), p.e70062_1 - e70062_14, 2025/10
Times Cited Count：1 Percentile：36.81(Radiology, Nuclear Medicine & Medical Imaging)Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ikeda, Mizuha*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Minami, Takahiro*; Takahashi, Tadayuki*; Watanabe, Shin*
Applied Radiation and Isotopes, 222, p.111845_1 - 111845_7, 2025/08
Times Cited Count：2 Percentile：65.74(Chemistry, Inorganic & Nuclear)Osawa, Takahito
miLab (Internet), 1 Pages, 2025/07
There are still many challenges to be overcome in implementing laboratory automation (LA), and it is difficult to say that the introduction of LA is progressing. Under such circumstances, the author has continued to develop LA systems with the aim of reducing manpower to the utmost limit. The first project was the automation of a prompt gamma-ray analysis system, which is an experimental device of a research reactor, followed by the automation of the analysis pretreatment of Sr-90, and finally the automation of the analysis pretreatment of Se-79. This paper introduces these three LA systems that the author has developed independently, and describes the methodology and know-how in their automation, as well as the effects of their implementation. Recent social implementation efforts are also introduced.
Chiu, I.-H.; Osawa, Takahito; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Takahashi, Tadayuki*; Katsuragawa, Miho*; Watanabe, Shin*; Kubo, Kenya*; Saito, Tsutomu*; Mizumoto, Kazumi*; et al.
npj Heritage Science (Internet), 13, p.154_1 - 154_9, 2025/05
Times Cited Count：2 Percentile：77.85(Humanities, Multidisciplinary)Osawa, Takahito
Materia, 64(3), p.153 - 156, 2025/03
In order to obtain accurate information on the elemental composition in a sample, it is very important to select an appropriate analytical method, and it is necessary to have a correct understanding of the advantages and disadvantages of each analytical method. This paper introduces prompt gamma-ray analysis as an unusual method that is different from elemental analysis methods that readers may be familiar with, and explains what makes it different from well-known analysis methods. The research on cultural properties conducted with the prompt gamma-ray analysis system (PGA) and future developments will also be described.
Ebihara, Mitsuru*; Shirai, Naoki*; Osawa, Takahito; Yamaguchi, Akira*
Geochimica et Cosmochimica Acta, 389, p.200 - 210, 2025/01
Times Cited Count：14 Percentile：97.01(Geochemistry & Geophysics)The 15 elements including most major elements of 12 carbonaceous chondrites collected in Antarctica were quantified using neutron-induced prompt gamma-ray analysis. While some of these samples were observed to share affinities with CI or CM chondrites, they do not exhibit the same characteristics as the known CI or CM chondrites. As a result, a new group named "CY" has been proposed for these meteorites. Common among the 12 meteorites is the depletion of volatile elements H and chlorine, showing a correlation and being depleted compared to non-Antarctic CI levels. Based on the abundance of moderately volatile elements Mn and S, the 12 meteorites can be divided into two groups: one with levels similar to non-Antarctic CI and the other with intermediate levels between CI and CM. These results suggest that CY chondrites originate from distinct parent bodies (materials), and considering two different parent bodies (materials) is necessary.
Sumita, Takehiro*; Osawa, Takahito; Chiu, I.-H.; Ikeda, Atsushi
Analytica Chimica Acta, 1329, p.343256_1 - 343256_10, 2024/11
Times Cited Count：5 Percentile：28.27(Chemistry, Analytical)Osawa, Takahito
Bunseki (Internet), 2024(11), p.428 - 434, 2024/11
Methods for fully automating complex wet chemistry operations will be described, using examples of laboratory automation systems that the author has developed.
Osawa, Takahito
Chikyu Kagaku, 58(3), p.70 - 82, 2024/09
This paper describes the recent research and development status of neutron-induced prompt gamma-ray analysis and muonic X-ray analysis as elemental analysis methods using quantum beams. Neutron-induced prompt gamma-ray analysis is an elemental analysis method using neutrons, and is often used as a nondestructive quantitative analysis method for boron and hydrogen. The prompt gamma-ray analysis system (PGA) installed at JRR-3 is an old device constructed more than 30 years ago, but recently an articulated robot has been installed and an advanced automated analysis system is in operation. On the other hand, the muonic X-ray analysis method is attracting attention as a new analysis method, and can detect light elements such as oxygen nondestructively. Both analytical methods have been used in the analysis of the samples of asteroid Ryugu, and will continue to evolve greatly as analytical methods in the future.
Ninomiya, Kazuhiko*; Osawa, Takahito; Terada, Kentaro*; Wada, Taiga*; Nagasawa, Shunsaku*; Chiu, I.-H.; Nakamura, Tomoki*; 40 of others*
Meteoritics & Planetary Science, 59(8), p.2044 - 2057, 2024/08
Times Cited Count：4 Percentile：46.47(Geochemistry & Geophysics)Samples from asteroid Ryugu, brought back by asteroid explorer Hayabusa2 are important for investigating the origin and evolution of the solar system. Here, we report the elemental compositions of a 123 mg Ryugu sample determined with a nondestructive muon elemental analysis method. This method is a powerful tool for determining bulk chemical composition, including light elements such as C, N, and O. From the muonic X-ray spectra with three carbonaceous chondrites, the relationship between the elemental composition and muonic X-ray intensity was determined for each element. Calibration curves showed linearity, and the elemental composition of Ryugu was quantitatively determined. The results reflect the average bulk elemental composition of asteroid Ryugu owing to the large amount of samples. Ryugu has an elemental composition similar to that of Orgueil (CI1), and should be classified as CI1. However, the O/Si ratio of Ryugu is 25% lower than that of Orgueil, indicating that Orgueil may have been seriously contaminated by terrestrial materials after its fall to Earth. These results indicate that the Ryugu sample is more representative than the CI chondrites as a solid material of the solar system.
Kim, J.*; Thompson, B. R.*; Tominaga, Taiki*; Osawa, Takahito; Egami, Takeshi*; F
rster, S.*; Ohl, M.*; Senses, E.*; Faraone, A.*; Wagner, N. J.*
ACS Macro Letters (Internet), 13(6), p.720 - 725, 2024/06
Times Cited Count：5 Percentile：28.65(Polymer Science)The Rouse dynamics of polymer chains in model nanocomposite PolyEthylene Oxide (PEO)/Silica NanoParticles (NPs) was investigated using QuasiElastic Neutron Scattering (QENS). The apparent Rouse rate of the polymer chains decreases as the particle loading increases. However, there is no evidence of an immobile segment population on the probed time scale of tens of ps. The slowing down of the dynamics is interpreted in terms of modified Rouse models for the chains in the NP inter-phase region. Thus, two chain populations, one bulk like and the other characterized by a suppression of Rouse modes, are identified. The spatial extent of the interphase region is estimated to be about twice the adsorbed layer thickness, or about 2 nm. These findings provide a detailed description of the suppression of the chain dynamics on the surface of NPs. These results are relevant insights on surface effects and confinement and provide a foundation for the understanding of the rheological properties of Polymer NanoComposites (PNCs) with well-dispersed NPs.
Terada, Kentaro*; Ninomiya, Kazuhiko*; Sato, Akira*; Tomono, Dai*; Kawashima, Yoshitaka*; Inagaki, Makoto*; Nambu, Akihiro*; Kudo, Takuto*; Osawa, Takahito; Kubo, Kenya*
Journal of Analytical Science and Technology, 15, p.28_1 - 28_7, 2024/05
Times Cited Count：2 Percentile：17.68(Chemistry, Analytical)In Earth and planetary science, Pb isotopic composition is well known to play a key role in deciphering the origin and evolution of materials because they provide unique chronological and/or indigenous regional information as a radiogenic daughter nuclide from U and Th. To determine such an isotopic composition, a mass spectrometer has been widely used over several decades, which requires a destructive treatment such as laser ablation and thermal ionization, so on. Here we first report the non-destructive Pb isotopic measurement of the natural galena (PbS) using an energy-shift of muon-induced characteristic X-rays. The observed Pb isotopic composition of the natural galena is in good agreement with that obtained by conventional mass spectrometry.
Osawa, Takahito
Kenkyu Kaihatsu Reda, 20(8), p.7 - 11, 2023/11
This review outlines technical methodologies for automating labor-intensive experiments, especially wet separation experiments.
Matsuoka, Moe*; Kagawa, Eiichi*; Amano, Kana*; Nakamura, Tomoki*; Tatsumi, Eri*; Osawa, Takahito; 51 of others*
Communications Earth & Environment (Internet), 4, p.335_1 - 335_12, 2023/09
Times Cited Count：25 Percentile：89.86(Environmental Sciences)Visible and near-infrared (Vis-NIR) spectra of returned samples from Cb-type asteroid (162173) Ryugu exhibit very low reflectance values and absorptions that are generally consistent with observations from the Hayabusa2 ONC-T and NIRS3 instruments. A notable difference is that a metal-OH absorption at 2.72 misrometer is more than twice as deep in laboratory sample spectra compared with those of Ryugu's surface. Based on the laboratory experiments to investigate the range of spectral variation by physical properties and space weathering, we conclude that the spectral differences between returned samples and asteroid surface are best explained by a combination of (1) porosity, (2) particle size, and (3) degree of space weathering effects, with the latter being the most effective. Those effects can explain spectral variations between Cb-type asteroids, suggesting that these asteroids consist of the same CI-chondrite material with different physical properties and weathering degrees. Extremely homogeneous Vis-NIR spectra of the entire Ryugu surface in comparison with the heterogeneous spectra of a near-Earth S-type asteroid (25143) Itokawa indicate that the space weathering has been processing more rapidly on Cb-type asteroids compared with S-type asteroids. Because the major component of Cb-type asteroids are porous hydrous silicates that have lower melting temperature and lower material strength than anhydrous silicates, the surface of Cb-type asteroids are more susceptible to the alteration by impacts of interplanetary dust particles.
