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Micheau, C.; Ueda, Yuki; Motokawa, Ryuhei; Akutsu, Kazuhiro*; Yamada, Norifumi*; Yamada, Masako*; Moussaoui, S. A.*; Makombe, E.*; Meyer, D.*; Berthon, L.*; et al.
Journal of Molecular Liquids, 401, p.124372_1 - 124372_12, 2024/05
Supramolecular organization of extractant molecules impacts metal ions separation behavior. Probing bulk and interfacial structures of the relevant systems is expected to provide key insights into the metal ion selectivity and kinetic aspects. The supramolecular features of two solvent extraction systems based on malonamide extractants THMA in toluene and DBMA in n-heptane were studied using small-angle X-ray scattering for the organic bulk phases, as well as interfacial tension and neutron reflectivity measurements for the interfaces. In the bulk solution, THMA forms dimeric/trimeric associates but no aggregates in toluene, while DBMA forms large aggregates in n-heptane. On the other hand, THMA accumulates in a diffuse layer at the interface at high THMA concentration, whereas DBMA forms a compact but thinner layer. After Pd(II) extraction, the thickness of interfacial layers decreases in the case of THMA, and totally vanishes in the case of DBMA. Based on these new structural information, two mechanisms are proposed for Pd(II) and Nd(III) extraction with malonamides. In toluene, THMA associates slightly accumulate in the vicinity of the interface, then coordinate Pd(II) and diffuse into the organic bulk phase. In n-heptane, DBMA aggregates adsorb at the interface then pick up Nd(III) cations in their polar cores and finally diffuse into the bulk.
Kaburagi, Masaaki; Yamada, Hironao*; Miyakawa, Takeshi*; Morikawa, Ryota*; Takasu, Masako*; Kato, Takamitsu*; Uesaka, Mitsuru*
Polymer Journal, 48(2), p.189 - 195, 2016/02
Times Cited Count：5 Percentile：18.64(Polymer Science)We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between 
(POT1) and O5' (telomeric ssDNA) is calculated to verify the binding system for 100 ns MD. We then calculated the distance between the bases of telomeric DNA ends and the root mean square deviation and gyration radius in single and binding states. We compared the root mean square fluctuations between single and binding states and calculated the number of hydrogen bonds between POT1 and telomeric DNA. There are many hydrogen bonds between Gln94 and the first guanine of the closest TTAGGG sequence in telomeric single-stranded DNA. These Gln94 and the guanine have a large difference in root mean square fluctuation between single and binding states. We found that Gln94 and guanine are important components of the binding system, and they are related to its stability.
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
Physical Review E, 88(5), p.052304_1 - 052304_8, 2013/11
Times Cited Count：3 Percentile：23.18(Physics, Fluids & Plasmas)no abstracts in English
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
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no abstracts in English
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Yamada, Masako*; Sada, Tomoko; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Fuwa, Yasuhiro; Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Hirota, Katsuya*; Yamada, Masako*; Kitaguchi, Masaaki*; Shimizu, Hirohiko*
no journal, ,
A neutron mirror with a magnetic repulsive wall is under development. Since neutrons have a magnetic dipole moment, they are subject to forces in a magnetic field gradient. Using this phenomenon, a potential wall for neutrons can be formed by arranging permanent magnets in a planar configuration of a Halbach array. This potential wall acts as a mirror for a polarized neutron beam. A prototype mirror 20 mm high and 30 mm wide was fabricated, and preliminary neutron reflection experiments were conducted at the MINE2 port of JRR-3. As the next step, we plan to fabricate a mirror with a larger size and conduct experiments at the J-PARC MLF. In this presentation, the principle of the mirror, the results of preliminary experiments at JRR-3, and the status of the mirror fabrication for the experiment at J-PARC will be reported.
Fuwa, Yasuhiro; Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Yamada, Masako*; Hirota, Katsuya*; Kitaguchi, Masaaki*; Shimizu, Hirohiko*
no journal, ,
Since neutrons have a spin magnetic moment, they are subject to a force due to their interaction with the magnetic field gradient. The direction of this force coincides with the direction of the magnetic field gradient vector, and the force acts in the opposite direction depending on the direction of the spin. By utilizing this force, the neutron beam can be manipulated. If the magnetic field gradient is transverse to the beam axis, the beam is deflected. Therefore, if a sextupole magnet is used to generate a magnetic field, the magnetic field gradient changes in proportion to the distance from the center of the beam axis, which causes the same effect as a lens, and the neutron beam can be focused. In addition, by arranging permanent magnets in a Halbach array on a plane and generating a uniform magnetic field gradient in the direction normal to the plane, a neutron beam reflecting wall can be formed, which can be combined in a duct-like configuration to form a guide tube. The magnetic field gradient in the longitudinal direction relative to the beam axis can change the energy of the neutrons. The integral value of this energy change is zero if the neutrons just pass through, but if the spins are flipped in the magnetic field gradient, the neutron beam can be accelerated or decelerated with the energy corresponding to the magnetic flux density at the flipped location. By applying this technique, spatial focusing and energy modulation of neutron beams are possible. In this presentation, the principle and configuration of the instruments we are developing for neutron beam manipulation and the planned experiments are described, and their potential applications are discussed.
