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Lanthanide and actinide ion complexes containing organic ligands investigated by surface-enhanced infrared absorption spectroscopy

平田 早紀子*; 日下 良二; 明地 省吾*; 為国 誠太*; 奥寺 洸介*; 浜田 昇賢*; 坂本 知優*; 本田 匠*; 松下 高輔*; 村松 悟*; et al.

Inorganic Chemistry, 62(1), p.474 - 486, 2023/01

 被引用回数:0 パーセンタイル:0.01(Chemistry, Inorganic & Nuclear)

A new technique, surface-enhanced infrared absorption (SEIRA) spectroscopy, was used for the structural investigation of lanthanide (Ln) and actinide (An) complexes containing organic ligands. We synthesized thiol derivatives of organic ligands with coordination sites similar to those of diglycolamide (DGA), Cyanex-272, and $$N,N,N',N'$$-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN), which have been used for separating Ln and An through solvent extraction. These ligands were attached on a gold surface deposited on an Si prism through S-Au covalent bonds; the gold surface enhanced the IR absorption intensity of the ligands. Aqueous solutions of Ln (Eu$$^{3+}$$, Gd$$^{3+}$$, Tb$$^{3+}$$) and An (Am$$^{3+}$$) ions were loaded onto the gold surface to form ion complexes. The IR spectra of the ion complexes were obtained using FT-IR spectroscopy in the attenuated total reflection mode. In this study, we developed a new sample preparation method for SEIRA spectroscopy that enabled us to obtain the IR spectra of the complexes with a small amount of ion solution (5 $$mu$$L). This is a significant advantage for the IR measurement of radiotoxic Am$$^{3+}$$ complexes. In the IR spectra of DGA, the band attributed to C=O stretching vibrations at $$sim$$1630 cm$$^{-1}$$ shifted to a lower wavenumber by $$sim$$20 cm$$^{-1}$$ upon complexation with Ln and An ions. Moreover, the amount of the red-shift was inversely proportional to the extraction equilibrium constant reported in previous studies on solvent extraction. The coordination ability of DGA toward Ln and An ions could be assessed using the band position of the C=O band. The Cyanex-272- and TPEN-like ligands synthesized in this report also showed noticeable SEIRA signals for Ln and An complexes. This study indicates that SEIRA spectroscopy can be used for the structural investigation of ion complexes and provides a microscopic understanding of selective extraction of Ln and An.


High-temperature gaseous reaction of cesium with siliceous thermal insulation; The Potential implication to the provenance of enigmatic Fukushima cesium-bearing material

Rizaal, M.; 中島 邦久; 斉藤 拓巳*; 逢坂 正彦; 岡本 孝司*

ACS Omega (Internet), 7(33), p.29326 - 29336, 2022/08

 被引用回数:0 パーセンタイル:0(Chemistry, Multidisciplinary)

Here we report an investigation of the gas-solid reaction between cesium hydroxide (CsOH) and siliceous (calcium silicate) thermal insulation at high temperature, which was postulated as the origin for the formation mechanism of cesium-bearing material emitted from the Fukushima Daiichi Nuclear Power Plant. A developed reaction furnace consisting of two heating compartments was used to study the reaction at temperatures of 873, 973, and 1073 K. Under the influence of hydrogen-steam atmospheric conditions (H$$_{2}$$/H$$_{2}$$O = 0.2), the reaction between cesium hydroxide vapor and solid thermal insulation was confirmed to occur at temperatures of 973 and 1073 K with the formation of dicalcium silicate (Ca$$_{2}$$SiO$$_{4}$$) and cesium aluminum silicate (CsAlSiO$$_{4}$$). Water-dissolution analyses of the reaction products have demonstrated their stability, in particular, the CsAlSiO$$_{4}$$. Constituents similarity of the field-observed cesium-bearing materials near the Fukushima Daiichi Nuclear Power Plants with CsAlSiO$$_{4}$$ suggests for the first time that gaseous reaction between CsOH with calcium silicate thermal insulation could be one of the original formation mechanisms of the cesium-bearing materials.


オールジャパンでとりくむ地層処分のいま,6; 処分場閉鎖後の安全評価(その2)

舘 幸男; 斉藤 拓巳*; 桐島 陽*

日本原子力学会誌ATOMO$$Sigma$$, 64(5), p.290 - 295, 2022/05



Volatilization of B$$_{4}$$C control rods in Fukushima Daiichi nuclear reactors during meltdown; B-Li isotopic signatures in cesium-rich microparticles

笛田 和希*; 高見 龍*; 蓑毛 健太*; 諸岡 和也*; 堀江 憲路*; 竹原 真美*; 山崎 信哉*; 斉藤 拓巳*; 塩津 弘之; 大貫 敏彦*; et al.

Journal of Hazardous Materials, 428, p.128214_1 - 128214_10, 2022/04

 被引用回数:2 パーセンタイル:75.54(Engineering, Environmental)

Boron carbide control rods remain in the fuel debris of the damaged reactors in the Fukushima Daiichi Nuclear Power Plant, potentially preventing re-criticality; however, the state and stability of the control rods remain unknown. Sensitive high-resolution ion microprobe analyses have revealed B-Li isotopic signatures in radioactive Cs-rich microparticles (CsMPs) that formed by volatilization and condensation of Si-oxides during the meltdowns. The CsMPs contain 1518-6733 mg kg$$^{-1}$$ of $$^{10+11}$$B and 11.99-1213 mg kg$$^{-1}$$ of Li. The $$^{11}$$B/$$^{10}$$B (4.15-4.21) and $$^{7}$$Li/$$^{6}$$Li (213-406) isotopic ratios are greater than natural abundances ($$sim$$4.05 and $$sim$$12.5, respectively), indicating that $$^{10}$$B(n,$$alpha$$)$$^{7}$$Li reactions occurred in B$$_{4}$$C prior to the meltdowns. The total amount of B released with CsMPs was estimated to be 0.024-62 g, suggesting that essentially all B remains in reactor Units 2 and/or 3 and is enough to prevent re-criticality; however, the heterogeneous distribution of B needs to be considered during decommissioning.


Dispersive XAFS Study on the Laser-Induced Reduction of a Rh$$^{3+}$$ ion complex; Presence of a Rh$$^{+}$$ Intermediate in Direct Photoreduction

佐伯 盛久*; 松村 大樹; 中西 隆造*; 蓬田 匠; 辻 卓也; 齋藤 寛之*; 大場 弘則*

Journal of Physical Chemistry C, 126(12), p.5607 - 5616, 2022/03

 被引用回数:1 パーセンタイル:56.41(Chemistry, Physical)

パルス紫外線レーザー照射によって引き起こされるRh$$^{3+}$$イオン錯体のRh$$^{0}$$種への直接光還元反応機構を、分散型X線吸収微細構造(DXAFS)分光法によって調べた。時間分解X線吸収端近傍構造(XANES)には等吸収点がなく、Rh$$^{3+}$$の直接光還元に2種類以上のRh$$^{n+}$$が寄与することを示した。時間分解XANESデータの特異値解析から、直接光還元には3つのRh$$^{n+}$$種が関与することが示唆された。時間分解XANESデータを、交互最小二乗法による多変量解析(MCR-ALS)により解析したところ、3つのRh$$^{n+}$$種の純粋なスペクトルと濃度プロファイルが得られた。Rh$$^{n+}$$種は、3つのXANESスペクトルの特徴から、Rh$$^{3+}$$, Rh$$^{+}$$, Rh$$^{0}$$種に分類できた。得られた濃度プロファイルから、Rhの直接光還元はRh$$^{3+}$$ $$rightarrow$$ Rh$$^{+}$$ $$rightarrow$$ Rh$$^{0}$$の順で進行することが示唆され、Rh$$^{3+}$$とRh$$^{+}$$の光還元、Rh$$^{3+}$$とRh$$^{+}$$の光による自己触媒的還元、Rh$$^{+}$$の光酸化による反応機構により、3種のRh$$^{n+}$$の濃度プロファイルがよく再現できることが示された。


Uranium (VI) sorption on illite under varying carbonate concentrations; Batch experiments, modeling, and cryogenic time-resolved laser fluorescence spectroscopy study

Mei, H.; 青柳 登; 斉藤 拓巳*; 香西 直文; 杉浦 佑樹; 舘 幸男

Applied Geochemistry, 136, p.105178_1 - 105178_8, 2022/01

 被引用回数:2 パーセンタイル:0.01(Geochemistry & Geophysics)

Dissolved inorganic carbonate ions (DIC) present in groundwaters may affect both the aqueous and surface species of U(VI) due to its strong complexation ability with U(VI). However, it is still not clear how DIC affects U(VI) sorption on illite, which is one of the critical components in argillaceous rocks. In this study, the sorption of U(VI) on conditioned illite du Puy in presence of varying DIC concentrations (up to 250 mM DIC) as a function of pH was investigated by combining batch sorption experiments, surface complexation modeling, and the cryogenic time-resolved laser fluorescence spectroscopy (TRLFS). The distribution coefficients of U(VI) were sensitive to the DIC concentration, which decreased with an increase of DIC. There is no sorption of U(VI) under relatively high DIC concentrations (100 mM DIC). The U(VI) sorption behavior on illite was modeled by using the 2 Site Protolysis Non-Electrostatic Surface Complexation and Cation Exchange model. Two ternary surface complexation reactions with carbonate were needed to depict the experimental sorption data in addition to binary and ternary hydroxo surface complexation reactions employed for the description of U sorption to illite without carbonate. The cryogenic TRLFS revealed that U(VI) did sorb to illite in presence of high DIC concentration (up to 10 mM DIC). The spectra were unchanged with DIC at pH 8.5, suggesting the surface speciation of U(VI) remained the same. The decay curves were biexponential, which further indicated that at least two species were responsible for the sorption. Our finding will help to predict the transport and retention behaviors of U(VI) near radioactive waste repositories.


Stoichiometry between humate unit molecules and metal ions in supramolecular assembly induced by Cu$$^{2+}$$ and Tb$$^{3+}$$ measured by gel electrophoresis techniques

中野 純佳*; 丸茂 和樹*; 風見 綸太郎*; 斉藤 拓巳*; 原賀 智子; 半田 友衣子*; 齋藤 伸吾*

Environmental Science & Technology, 55(22), p.15172 - 15180, 2021/11

 被引用回数:2 パーセンタイル:28.48(Engineering, Environmental)



Microparticles with diverse sizes and morphologies from mechanical and laser cutting of fuel debris simulants and geopolymer as a covering material

Zhou, Q.*; 斉藤 拓巳*; 鈴木 誠矢; 矢野 公彦; 鈴木 俊一*

Journal of Nuclear Science and Technology, 58(4), p.461 - 472, 2021/04

 被引用回数:2 パーセンタイル:30.57(Nuclear Science & Technology)

During the decommissioning of Fukushima Daiichi Nuclear Power Plant, the dismantling of massive fuel debris is important for the defueling process. The production and dispersion of radioactive microparticles highly depends on the cutting technique implemented. Previous studies have been conducted on the development of cutting techniques and the treatment of radioactive particles generation during the cutting process. Besides, adequate understanding of the microparticle products during the cuttings of fuel debris is of vital necessity. Nowadays, geopolymer application is proposed as a covering material during the fuel debris retrieval in order to keep the structural integrity of damaged components. In this study, the microparticle products during mechanical and laser cutting of fuel debris simulants (Hafnium oxide and Tungsten(IV) oxide pellets) and geopolymer material were investigated. The cuttings have been carried out for samples of the simulants, geopolymer, and simulants with geopolymer covering. The generated particles were collected and investigated by laser diffraction particle size analyzer and Scanning Electron Microscope with X-ray spectrometry. Particles with diverse sizes and morphologies were observed from the products of each sample. It also appears that particles with unique sizes and morphologies can generate from the laser cuttings due to the thermal effect of laser cutting.


Application of an augmentation method to MCR-ALS analysis for XAFS and Raman data matrices in the structural change of isopolymolybdates

佐伯 盛久*; 蓬田 匠; 松村 大樹; 斉藤 拓巳*; 中西 隆造*; 辻 卓也; 大場 弘則*

Analytical Sciences, 36(11), p.1371 - 1378, 2020/11

 被引用回数:2 パーセンタイル:15.8(Chemistry, Analytical)

モリブデンイオンMoO$$_{4}$$$$^{2-}$$水溶液に酸を加えると、複数のモリブデン原子が酸素を介して結合したポリモリブデン酸が形成され、さらに酸濃度に応じてポリモリブデン酸の化学形態は大きく変化する。我々は、これまで研究例の少なかった高酸性水溶液中(0.15-4.0M)でのポリモリブデン酸の化学形態を、ラマン分光法およびX線吸収微細構造(XAFS)分光法により調べ、測定したスペクトルを多変量スペクトル分解法(MCR-ALS)により解析した。MCR-ALS解析では実験データ解析により得られるスペクトルの任意性が問題になり、XAFSデータのみの解析ではこれが顕著になるが、XAFSデータとラマンデータを同時にMCR-ALS解析することで、信頼性の高い3成分のXAFSスペクトルを得ることに成功した。構造解析の結果から、硝酸濃度が高くなるにつれポリモリブデン酸の化学種が[Mo$$_{36}$$O$$_{112}$$(H$$_{2}$$O)$$_{16}$$]$$^{2+}$$$$rightarrow $$[Mo$$_{2}$$O$$_{5}$$(H$$_{2}$$O)$$_{6}$$]$$^{2+}$$$$rightarrow $$[HMoO$$_{3}$$(H$$_{2}$$O)$$_{3}$$]$$^{+}$$へと変化する様子を明らかにした。


Investigation of high-temperature chemical interaction of calcium silicate insulation and cesium hydroxide

Rizaal, M.; 中島 邦久; 斉藤 拓巳*; 逢坂 正彦; 岡本 孝司*

Journal of Nuclear Science and Technology, 57(9), p.1062 - 1073, 2020/09

 被引用回数:6 パーセンタイル:73.86(Nuclear Science & Technology)



Modulation of Dirac electrons in epitaxial Bi$$_2$$Se$$_3$$ ultrathin films on van der Waals ferromagnet Cr$$_2$$Si$$_2$$Te$$_6$$

加藤 剛臣*; 菅原 克明*; 伊東 直洋*; 山内 邦彦*; 佐藤 匠*; 小口 多美夫*; 高橋 隆*; 塩見 雄毅*; 齊藤 英治; 佐藤 宇史*

Physical Review Materials (Internet), 4(8), p.084202_1 - 084202_6, 2020/08

 被引用回数:3 パーセンタイル:22.66(Materials Science, Multidisciplinary)

We investigated the Dirac-cone state and its modulation when an ultrathin film of topological insulator Bi$$_2$$Se$$_3$$ was epitaxially grown on a van der Waals ferromagnet Cr$$_2$$Si$$_2$$Te$$_6$$ (CST) by angle-resolved photoemission spectroscopy. We observed a gapless Dirac-cone surface state in six quintuple-layer (6QL) Bi$$_2$$Se$$_3$$ on CST, whereas the Dirac cone exhibits a gap of 0.37 eV in its 2QL counterpart. Intriguingly, this gap is much larger than those for Bi$$_2$$Se$$_3$$ films on Si(111). We also revealed no discernible change in the gap magnitude across the ferromagnetic transition of CST, suggesting the very small characteristic length and energy scale of the magnetic proximity effect. The present results suggest a crucial role of interfacial coupling for modulating Dirac electrons in topological-insulator hybrids.


Room-temperature adsorption behavior of cesium onto calcium silicate insulation

Rizaal, M.; 斉藤 拓巳*; 岡本 孝司*; Erkan, N.*; 中島 邦久; 逢坂 正彦

Mechanical Engineering Journal (Internet), 7(3), p.19-00563_1 - 19-00563_10, 2020/06



Advanced gel electrophoresis techniques reveal heterogeneity of humic acids based on molecular weight distributions of kinetically inert Cu$$^{2+}$$-humate complexes

丸茂 和樹*; 松本 篤正*; 中野 純佳*; 渋川 雅美*; 斉藤 拓巳*; 原賀 智子; 齋藤 伸吾*

Environmental Science & Technology, 53(24), p.14507 - 14515, 2019/12

 被引用回数:6 パーセンタイル:32.47(Engineering, Environmental)

フミン酸(HA)は環境中に存在する不定形有機高分子であり、環境中の有害重金属や放射性金属イオンと錯形成し、それらの動態を制御している。そのため、土壌や河川の環境評価や放射性廃棄物処分の安全評価において、HAによる金属イオンの保持挙動を解明することが重要である。本研究では、HAに保持された銅イオンの分子量分布を評価するため、ポリアクリルアミドゲル電気泳動法(PAGE)を基盤とした新規分析法を開発した。本法により、HAに対して高い分離能を有し、かつ泳動場の汚染金属イオンを抑制することが可能となり、HAの分子量に対する精確な金属イオン分布を得ることに成功した。また、PAGE, UV-Vis測定および励起蛍光マトリクス-平行因子分析を組み合わせることにより、HAの分子量,金属イオン分布およびHA蛍光成分分布の相関を評価することにも成功した。本研究により、HA中の金属イオン配位サイトやHA蛍光成分はHAの分子量に対して不均一に分布しており、HAによる金属イオンの保持挙動は金属イオンの電荷や立体配位座によって大きく異なることを明らかにした。


Reduction behaviors of permanganate by microbial cells and concomitant accumulation of divalent cations of Mg$$^{2+}$$, Zn$$^{2}$$+, and Co$$^{2+}$$

加藤 友彰*; Yu, Q.*; 田中 万也; 香西 直文; 斉藤 拓巳*; 大貫 敏彦

Journal of Environmental Sciences, 86, p.78 - 86, 2019/12

 被引用回数:1 パーセンタイル:5.63(Environmental Sciences)



Structural approach to understanding the solubility of metal hydroxides

小林 大志*; 中嶋 翔梧*; 元川 竜平; 松村 大樹; 斉藤 拓巳*; 佐々木 隆之*

Langmuir, 35(24), p.7995 - 8006, 2019/06

 被引用回数:2 パーセンタイル:11.25(Chemistry, Multidisciplinary)

We report the hierarchical structure of zirconium hydroxide after aging at different temperatures to elucidate the factors governing zirconium solubility in aqueous solutions. Zirconium hydroxide solid phases after aging at 25, 40, 60, and 90$$^{circ}$$C under acidic to alkaline conditions were investigated using extended X-ray absorption fine structure (EXAFS) and wide- and small-angle X-ray scattering (WAXS and SAXS) techniques to reveal the bulk and surface structures of the solid phases from the nanoscale to submicroscale. After aging at 25 $$^{circ}$$C, the fundamental building unit of the solid phase was a zirconium hydroxide tetramer. The tetramers formed primary particles approximately 3 nm in size, which in turn formed aggregates hundreds of nanometers in size. This hierarchical structure was found to be stable up to 60 $$^{circ}$$C under acidic and neutral conditions and up to 40 $$^{circ}$$C under alkaline conditions. After aging at 90 $$^{circ}$$C under acidic conditions and at 60 and 90 $$^{circ}$$C under alkaline conditions, the WAXS and EXAFS measurements suggested the crystallization of the solid phase. The transformation of the solid-phase structure by temperature was discussed in relation to the solubility product to understand the solubility-limiting solid phase. The solubility of zirconium hydroxide after aging at different temperatures was governed not only by the size of the primary particles, but also by their surface configuration.


New precise measurements of muonium hyperfine structure at J-PARC MUSE

Strasser, P.*; 阿部 充志*; 青木 正治*; Choi, S.*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 勝彦*; et al.

EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01

 被引用回数:12 パーセンタイル:99.51

High precision measurements of the ground state hyperfine structure (HFS) of muonium is a stringent tool for testing bound-state quantum electrodynamics (QED) theory, determining fundamental constants of the muon magnetic moment and mass, and searches for new physics. Muonium is the most suitable system to test QED because both theoretical and experimental values can be precisely determined. Previous measurements were performed decades ago at LAMPF with uncertainties mostly dominated by statistical errors. At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is planning complementary measurements of muonium HFS both at zero and high magnetic field. The new high-intensity muon beam that will soon be available at H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation for high-field measurements, and the latest results at zero field are presented.


In Situ Time-Resolved XAFS Studies on Laser-induced Particle Formation of Palladium Metal in an Aqueous/EtOH solution

佐伯 盛久*; 松村 大樹; 蓬田 匠; 田口 富嗣*; 辻 卓也; 齋藤 寛之*; 大場 弘則*

Journal of Physical Chemistry C, 123(1), p.817 - 824, 2019/01

 被引用回数:11 パーセンタイル:54.62(Chemistry, Physical)

PdCl$$_{4}$$$$^{2-}$$水溶液にパルスレーザーを照射した際の、パラジウム(Pd)微粒子の形成反応メカニズムを透過型電子顕微鏡(TEM)、およびエネルギー分散型X線吸収分光法(DXAFS)を用いて調べた。266 nmの波長のナノ秒レーザー照射により形成されたPd微粒子をTEMにより観測した結果、微粒子径が照射レーザーのフルエンスに依存し、高フルエンスのレーザー照射が微粒子形成を促進することを明らかにした。DXAFSの結果よりPd$$^{2+}$$の濃度を算出し、Finke-Watzkyの二段階反応に基づいた解析を行った。その結果、照射するレーザーのフォトンは、1光子過程のPdCl$$_{4}$$$$^{2-}$$の還元と、多光子過程のPd微粒子の自己触媒的な成長に寄与することを見出した。


Characterization and thermodynamic study of humic acid in deep groundwater at Horonobe, Hokkaido, Japan

紀室 辰伍*; 桐島 陽*; 長尾 誠也*; 斎藤 拓巳*; 天野 由記; 宮川 和也; 秋山 大輔*; 佐藤 修彰*

Journal of Nuclear Science and Technology, 55(5), p.503 - 515, 2018/05

 被引用回数:4 パーセンタイル:44.5(Nuclear Science & Technology)



Europium binding to humic substances extracted from deep underground sedimentary groundwater studied by time-resolved laser fluorescence spectroscopy

斉藤 拓巳*; 青柳 登; 寺島 元基

Journal of Nuclear Science and Technology, 54(4), p.444 - 451, 2017/04

 被引用回数:4 パーセンタイル:41.83(Nuclear Science & Technology)



Sorption of Eu$$^{3+}$$ on Na-montmorillonite studied by time-resolved laser fluorescence spectroscopy and surface complexation modeling

佐々木 隆之*; 上田 健揚*; 斉藤 拓巳; 青柳 登; 小林 大志*; 高木 郁二*; 木村 貴海; 舘 幸男

Journal of Nuclear Science and Technology, 53(4), p.592 - 601, 2016/04

 被引用回数:12 パーセンタイル:78.53(Nuclear Science & Technology)

ナトリウム型モンモリロナイトへのEu(III)の収着に対するpH, Eu濃度,硝酸塩濃度の影響について、バッチ収着試験と時間分解型レーザー誘起蛍光分光(TRLFS)によって調査された。0.01M硝酸ナトリウム中では分配係数(Kd)はpHにほとんど依存せず、一方で、1M硝酸ナトリウム中ではKdはpHに大きく依存した。陽イオン交換モデルと1サイトの静電補正を考慮しない表面錯体モデルを組み合せたモデルによってKdデータが解釈された。Eu表面化学種に対するTRLFSスペクトルはパラレル因子分析法(PARAFAC)により解析され、1つの外圏錯体(ファクターA)と2つの内圏錯体(ファクターB及びC)への対応が示唆された。ファクターAとBは、イオン交換サイトへ収着したEu、エッジの水酸基との内圏錯体に、それぞれ対応するものである。ファクターCは比較的高いpH、イオン強度条件で支配的であり、表面におけるEu(OH)$$_{3}$$の析出物と評価された。

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