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増田 優花*; 阪田 潮実*; 萱原 早織*; 入江 夏生*; 古府 麻衣子; 河野 洋平*; 榊原 俊郎*; 堀井 洋司*; 梶原 孝志*
Journal of Physical Chemistry C, 127(6), p.3295 - 3306, 2023/02
Trinuclear M(II)-Gd(III)-M(II) complexes 1 (M = Zn), 2 (M = Mg), and the magnetically dilute sample 1' were synthesized and the slow magnetization relaxation originating from Gd(III) ions was investigated in detail. These complexes are crystallographically isostructural and belong to point group symmetry, with M-Gd-M arrayed on the crystallographic 3-fold axis. From the angular-resolved magnetization of a single crystal of 1, an easy-axis-type magnetic anisotropy of Gd(III) with an anisotropy parameter D of -0.21(3) K were revealed. All the complexes underwent slow relaxation under the application of an external magnetic field. The temperature dependence of the relaxation rate differed considerably between 1' and 1, 2. The discrepancy can be attributed to the presence of competing multiple relaxation processes, such as direct and Raman processes, and at dilution, the direct process becomes faster, leading to its predominance in 1'. For 1 and 2, the larger power number (~1.5) was attributed to the significantly greater contribution from the Raman process, which may be originated from intramolecular atomic vibrations.
山田 椋平; 河野 恭彦; 中嶌 純也; 廣内 淳; 辻 智也; 梅田 昌幸; 五十嵐 悠*; 小池 弘美*
保健物理(インターネット), 56(1), p.32 - 38, 2021/03
本報告は、日本保健物理学会若手研究会・学友会が2010年から取り組んできた社会コミュニケーション活動である千葉市科学フェスタ(2010年は「科学技術カフェシエスタ」)への出展について、10回目の出展を機に、出展当初の経緯を振り返りつつ、近年の活動について取りまとめたものである。
中村 翔太*; 榊原 俊郎*; 清水 悠晴*; 橘高 俊一郎*; 河野 洋平*; 芳賀 芳範; Pospisil, J.; 山本 悦嗣
Progress in Nuclear Science and Technology (Internet), 5, p.123 - 127, 2018/11
Dc magnetization measurements have been performed on the orthorhombic Ising ferromagnet Urge. We observed a clear first-order reorientation transition with a small hysteresis and estimated the tricritical point to be around 4 K. The magnetization and the thermal expansion data indicate the presence of a characteristic temperature of about 1 K.
藤村 明央*; 安井 幸夫*; 井川 直樹; 吉田 幸彦*; 石垣 徹*; 河野 洋平*; 橘高 俊一郎*; 榊原 俊郎*
no journal, ,
CuOリボン鎖系CsCuMoOは、同様の構造を持つRbCuMoOとは異なる磁気的基底状態をとる。そこで本報では、比熱測定によって、新たにCsCuMoOの磁気相図を作成した。その結果、ゼロ磁場中ではT=1.85Kで反強磁性体の磁気転移を示すことが分かった。さらに中性子散乱実験によってCsCuMoOの磁気構造と結晶構造を決定し、RbCuMoOとの違いを議論する。
立和名 博昭*; 有村 泰宏*; 松本 亮平*; 滝沢 由政*; 堀 哲也*; 松本 淳; 小田 隆*; 佐藤 衛*; 河野 秀俊; 深川 竜郎*; et al.
no journal, ,
Centromeres are specific region of chromosomes, which ensure equal chromosome segregation in mitosis. The histone H3 variant, CENP-A, is a key protein for the establishment and maintenance of centromeres. However, little is known about how the incorporation of CENP-A into the chromatin leads to the centromere formation. We reported that a nucleosome containing human CENP-A (CENP-A nucleosome) has different structural feature, by which the CENP-A nucleosome may contribute to organize a unique chromatin structure in centromeres1. Then, we further analysed whether CENP-A nucleosome affects the poly-nucleosome structure using reconstituted tri-nucleosomes. To enable this, we reconstituted the tri-nucleosome, in which single CENP-A nucleosome is arranged at the centre, and two H3 nucleosomes are arranged on the both sides (H3-CA-H3 nucleosomes), by anucleosome-ligation method. Then, we analyzed structures of H3-CA-H3 nucleosomes and control H3-H3-H3 nucleosomes by dynamic light scattering, small angle X-ray scattering, and electron microscopic analyses. We found that single CENP-A nucleosome significantly alters higher order chromatin configuration. Based on these analyses, we propose a chromatin structure containing CENP-A nucleosomes and discuss the advantage of this structure in centromere formation and maintenance.
藤村 明央*; 安井 幸夫*; 河野 洋平*; 橘高 俊一郎*; 榊原 俊郎*; 井川 直樹; 松川 健*; 吉田 幸彦*; 星川 晃範*; 石垣 徹*
no journal, ,
CuOリボン鎖系ACuMoO (A=Rb, Cs)について、磁気比熱を測定し、中性子回折実験によってそれら物質の磁気構造を解析した。CsCuMoOの中性子回折実験では、磁気反射は全て核反射上に観察されたことなどから、本物質はcollinearな反強磁性を持つことが分った。これらの結果を基にACuMoO (A=Rb, Cs)の磁気的挙動と磁気構造の関係について議論を行う。