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Evaluation of electronic state of Cs-adsorbed clay minerals by NEXAFS analysis using DFT calculations

鈴木 知史; 矢板 毅; 鈴木 伸一; Pacold, J.*; Altman, A. B.*; Minasian, S. G.*; Tyliszczak, T.*; Shuh, D. K.*; 吉田 啓之; 逢坂 正彦

Journal of Physics and Chemistry of Solids, 127, p.169 - 177, 2019/04

 被引用回数:1 パーセンタイル:11.24(Chemistry, Multidisciplinary)

密度汎関数法(DFT: density-functional theory)を用いて、Cs M$$_{4,5}$$ X線吸収端近傍微細構造(NEXAFS: near-edge X-ray absorption fine structure)スペクトルを解析する手法を確立し、粘土鉱物中のCsの電子状態を評価した。各種のCsハロゲン化物のDFTによる解析を行うことにより、内殻空孔強度を組み込みその値を最適化して、NEXAFSスペクトルの再現に成功した。本DFTによる解析手法を用いて、粘土鉱物のCs M$$_{4,5}$$ NEXAFSスペクトルを解析したところ、主要な遷移およびテール構造を含めて、実験によるNEXAFSスペクトルを良好に再現することができた。本手法を用いて、電荷密度や電子状態の解析を行い、NEXAFSスペクトルに現れる構造が結合状態およびCs原子の周りの局所環境を反映する可能性が高いこと、粘土鉱物中においてCsと最近接原子との相互作用が最も大きいこと等を示した。


Complexation properties and structural character of lanthanides complexes of $$O,N$$-hetero donor ligand BIZA

小林 徹; 阿久津 和宏*; 中瀬 正彦*; 鈴木 伸一; 塩飽 秀啓; 矢板 毅

Separation Science and Technology, 54(13), p.2077 - 2083, 2019/02

 被引用回数:2 パーセンタイル:21.36(Chemistry, Multidisciplinary)



Quantitative analysis of Cs extraction by some dialkoxycalix[4]arene-crown-6 extractants

Simonnet, M.; 宮崎 有史*; 鈴木 伸一; 矢板 毅

Solvent Extraction and Ion Exchange, 37(1), p.81 - 95, 2019/00

 被引用回数:1 パーセンタイル:10.07(Chemistry, Multidisciplinary)

Cesium extraction from acidic media by seven dialkoxy-calix[4]arene-crown-6 compounds in several diluents was studied. 2-Nonanone was found to be a suitable diluent for cesium extraction. Nitric acid concentration variation reveals a maximum distribution ratio, whose position depends on extractant and diluent. This maximum was explained quantitatively by a competitive extraction of H$$^{+}$$. An analytical mass-action extraction model accounting for activity effects is proposed that fits correctly the different datasets. The analysis showed a nitrate hyper-stoichiometry in alkyl ketone diluents. This effect yields efficient back-extraction at low acidity. Benzo substitution on the crown ether lowers nitric acid extraction, improves sodium separation, but also degrades potassium and rubidium separation.


Cesium liquid-liquid extraction by calix-crown ethers; Solvent effect

Simonnet, M.; 宮崎 有史; 鈴木 伸一; 矢板 毅

Progress in Nuclear Science and Technology (Internet), 5, p.66 - 69, 2018/11

$$^{137}$$Cs is a dangerous fission product because of its half-life of 30 years and its high production yield. After several years, it becomes one of the main heat generator in nuclear waste; it would thus be beneficial to remove it before deep repository storage. Cesium also shows high mobility in the environment, thus being one of the most dangerous material released in accidental situation. Because the chemistry of cesium is close to these of sodium and potassium, found in great amount in water, cesium recovery requires very high separation factor towards these elements. Calix-crown-ether compounds show high extraction of Cs, and Na separation factor up to million (up to ten thousands for K), depending on experimental conditions and extractant structure. This study attempts to qualitatively and, when possible, quantitatively describe these dependencies. Focus has been made on HNO$$_{3}$$ concentration (0.01M to 6M), solvent nature, and extractant structure, based on the already well-documented di-octyloxy-calix[4]mono-crown-6.


Absorbent property of fullerene for cesium isotope separation investigated using X-ray photoelectron spectroscopy

関口 哲弘; 横山 啓一; 魚住 雄輝*; 矢野 雅大; 朝岡 秀人; 鈴木 伸一; 矢板 毅

Progress in Nuclear Science and Technology (Internet), 5, p.161 - 164, 2018/11



Lanthanides complexation properties of O, N-hetero donor ligand PTA

小林 徹; 鈴木 伸一; 塩飽 秀啓; 矢板 毅

Progress in Nuclear Science and Technology (Internet), 5, p.74 - 77, 2018/11

特定のアクチノイドを効率的に分離できる抽出剤の開発は、核燃料サイクルにおける分離法や放射性廃棄物の処分方法の開発に関連する重要なテーマである。本研究では、N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide (PTA)のランタノイドとの錯形成特性について、単結晶X線構造解析や広域X線吸収微細構造(EXAFS)法などを用いた構造解析に基づいて検討した。その結果、PTAは結晶系でも溶液中でも、ランタノイドに対して2分子が配位すること、2つのフェナントロリン窒素と1つのアミド酸素を介して3座配位子として配位することを明らかにした。また、Eu錯体とNd錯体とでその配位結合距離に僅かな変化が見られたが、その変化はランタノイドのイオン半径の違いに対応しており、イオンサイズの僅かな違いは配位特性に大きな影響は及ぼさないことが示された。


Measurement of water-steam flow behavior and pressure distribution in venturi scrubber

上澤 伸一郎; 堀口 直樹; 鈴木 貴行*; 柴田 光彦; 吉田 啓之

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 11 Pages, 2018/10

A venturi scrubber is one of the filtered venting systems and removes fuel productions (FPs) by spraying with the scrubbing water by self-priming. The FPs removal performance of the system was confirmed by various tests. However, the flow pattern of the water-steam two-phase flow and pressure distributions in the venturi scrubber which is one of the most important factors for the removal performance has not been experimentally clarified. In this study, water-steam flow behavior and pressure distributions in a single venturi scrubber were measured. The experiment resulted in the scrubbing water decreased with increasing the steam throat velocity with the increase of the throat pressure. On the lower steam velocity conditions, spray was generated from the wavy of the water column ejected from the water supply pores. The water film was generated with the increase of even higher velocity. The pressures for each position in the venturi nozzle were almost the same and approximately 100 kPa in the self-priming mode. On the scrubbing water stop condition, the pressure was higher at the throat than the water head pressure and negative pressure at the downstream of the throat. The result indicate that the scrubbing water can be supplied at this position on the decrease and the stop conditions of the supplied scrubbing water with the high steam velocity.



上澤 伸一郎; 鈴木 貴行*; 吉田 啓之

混相流シンポジウム2018講演論文集(インターネット), 2 Pages, 2018/08



Proposed cesium-free mineralization method for soil decontamination; Demonstration of cesium removal from weathered biotite

本田 充紀; 下山 巖; 小暮 敏博*; 馬場 祐治; 鈴木 伸一; 矢板 毅

ACS Omega (Internet), 2(12), p.8678 - 8681, 2017/12

 被引用回数:3 パーセンタイル:18.22(Chemistry, Multidisciplinary)

The possibility to remove sorbed cesium (Cs) from weathered biotite (WB), which is considered a major Cs-adsorbent in the soil of Fukushima, has been investigated by the addition of NaCl-CaCl$$_{2}$$ mixed salt and subsequent heat treatment in a low pressure. X-ray fluorescence analysis was employed to determine the Cs removal rate with elevated temperature. The structural changes and new phases formed were determined using powder X-ray diffraction, as well as electron diffraction and X-ray microanalysis in a transmission electron microscope. We found that Cs was completely removed from the specimen heated at 700 $$^{circ}$$C, when WB completely decomposed and augite with a pyroxene structure was formed. On the basis of this finding, we propose the cesium-free mineralization (CFM) method, a new soil decontamination process by means of transformation of Cs-sorbing minerals to those where Cs is impossible to be incorporated, by heating with certain additives.


Reduction and resource recycling of high-level radioactive wastes through nuclear transmutation; Isolation techniques of Pd, Zr, Se and Cs in simulated high level radioactive waste using solvent extraction

佐々木 祐二; 森田 圭介; 伊藤 圭祐; 鈴木 伸一; 塩飽 秀啓; 高橋 優也*; 金子 昌章*; 大森 孝*; 浅野 和仁*

Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09

高レベル廃液中のPd, Zr, Se, Csは長半減期核種のPd-107, Zr-93, Se-79, Cs-135を有している。高レベル廃液から除去し、核変換により処分することで、環境負荷低減に役立てることができる。これら元素について、PdはMIDOA, NTAアミド、Csはクラウンエーテル、ZrはTODGA, HDEHP, Seはフェニレンジアミンで抽出可能である。それぞれ元素の回収条件について検討した成果について述べる。


A Chemiluminescence sensor with signal amplification based on a self-immolative reaction for the detection of fluoride ion at low concentrations

久松 秀悟; 鈴木 伸一; 幸本 重男*; 岸川 圭希*; 山本 雄介*; 元川 竜平; 矢板 毅

Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07

 被引用回数:11 パーセンタイル:60.05(Chemistry, Organic)

A sensory system incorporated with an amplification function was developed for detection of trace-level fluoride ions. This sensory system comprises two steps, namely, amplification, and chemiluminescence. These steps were linked with chemical reactions and were induced continuously. The process from amplification to chemiluminescence was accomplished in the system by using fluoride ions. The amplification was based on a self-immolative system, which permitted the detection of emissions even at low fluoride ion concentration for system in which chemiluminescence cannot be induced in the absence of fluoride ions. An optical ratio of the chemiluminescent compound and the amplifier was calculated for achieving efficient amplification.


Extraction and separation of Se, Zr, Pd, and Cs including long-lived radionuclides

佐々木 祐二; 森田 圭介; 鈴木 伸一; 塩飽 秀啓; 伊藤 圭祐; 高橋 優也*; 金子 昌章*

Solvent Extraction Research and Development, Japan, 24(2), p.113 - 122, 2017/06

硝酸溶液からオクタノールまたはドデカン溶媒へのSe, Zr, Pd, Csの溶媒抽出を行った。これら元素は長半減期の核種を含み、高レベル廃液の処理にとってこれら元素の簡便な分離方法の開発が不可欠である。Seはフェニレンジアミン、ZrはHDEHP又はTODGA、PdはMIDOA又はNTAアミドで抽出可能である。CsはDtBuDB18C6を用いて、抽出溶媒を水相の10倍を用いることで90%回収を達成できることを確認した。



下山 巖; 本田 充紀; 小暮 敏博*; 馬場 祐治; 平尾 法恵*; 岡本 芳浩; 矢板 毅; 鈴木 伸一

Photon Factory News, 35(1), p.17 - 22, 2017/05



Mechanism of Cs removal from Fukushima weathered biotite by heat treatment with a NaCl-CaCl$$_{2}$$ mixed salt

本田 充紀; 岡本 芳浩; 下山 巖; 塩飽 秀啓; 鈴木 伸一; 矢板 毅

ACS Omega (Internet), 2(2), p.721 - 727, 2017/02

 被引用回数:14 パーセンタイル:58.98(Chemistry, Multidisciplinary)

An in situ extended X-ray absorption fine structure (in situ EXAFS) spectroscopic analysis at high temperature was conducted to investigate the mechanism of Cs removal from weathered biotite (WB) from Fukushima, induced by heating with a mixed salt of NaCl and CaCl$$_{2}$$. This indicated that most Cs remained in WB during heating at 200-700$$^{circ}$$C. In addition, the in situ EXAFS spectra gradually changed on heating with the mixed salt and a completely different spectrum was observed for the sample after cooling from 700$$^{circ}$$C to room temperature. Ex situ EXAFS measurements and X-ray fluorescence analyses were also conducted on samples after heat treatment and removal of the mixed salt to clarify the temperature dependence of the Cs removal ratio. Based on the results of radial structure function analysis obtained from in situ EXAFS, we concluded that almost all Cs was removed from WB by heating at 700$$^{circ}$$C with the mixed salt, and that Cs formed CsCl bonds after cooling to room temperature from 700$$^{circ}$$C. In contrast, although more than half of the Cs present was removed from WB by heat treatment at 500$$^{circ}$$C, most Cs was surrounded by silica tetrahedrons, maintained by Cs-O bonds. On the basis of these results, different Cs removal processes are suggested for the high-temperature (600-700$$^{circ}$$C) and low-temperature (400-500$$^{circ}$$C) regions.


Origin of robust nanoscale ferromagnetism in Fe-doped Ge revealed by angle-resolved photoemission spectroscopy and first-principles calculation

坂本 祥哉*; 若林 勇希*; 竹田 幸治; 藤森 伸一; 鈴木 博人*; 伴 芳祐*; 山上 浩志; 田中 雅明*; 大矢 忍*; 藤森 淳*

Physical Review B, 95(7), p.075203_1 - 075203_5, 2017/02

 被引用回数:8 パーセンタイル:50.8(Materials Science, Multidisciplinary)

Ge$$_{1-x}$$Fe$$_x$$ (Ge:Fe) shows ferromagnetic behavior up to a relatively high temperature of 210 K and hence is a promising material for spintronic applications compatible with Si technology. We have studied its underlying electronic structure by soft X-ray angle-resolved photoemission spectroscopy measurements and first-principles supercell calculation. We observed finite Fe 3$$d$$ components in the states at the Fermi level ($$Erm_F$$) in a wide region of momentum space, and the $$Erm_F$$ was located $$sim$$0.35 eV above the valence-band maximum of the host Ge. Our calculation indicates that the $$Erm_F$$ is also within the deep acceptor-level impurity band induced by the strong $$p$$-$$d$$($$t_2$$) hybridization. We conclude that the additional minority-spin $$d(e)$$ electron characteristic of the Fe$$^{2+}$$ state is responsible for the short-range ferromagnetic coupling between Fe atoms.


J-PARC 3MeVリニアック用制御システム開発

澤邊 祐希*; 石山 達也; 高橋 大輔; 加藤 裕子; 鈴木 隆洋*; 平野 耕一郎; 武井 早憲; 明午 伸一郎; 菊澤 信宏; 林 直樹

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (インターネット), p.647 - 651, 2016/11



Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

元川 竜平; 小林 徹; 遠藤 仁*; 池田 隆司; 矢板 毅; 鈴木 伸一; 成田 弘一*; 阿久津 和宏*; Heller, W. T.*

Journal of Nuclear Science and Technology, 53(8), p.1205 - 1211, 2016/08

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)

This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl substituted dibenzo-20-crown-6-ether (ace-DB20C6) with Cs. SANS profiles obtained for the complex of ace-DB20C6 and Cs (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs coordination resulted in a more compact structure than the free ace-DB20C6. The data were fit well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on a density functional theory calculation. Consequently, we conclude that the SANS analysis experimentally supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs is formed with an ace-DB20C6/Cs molar ratio of 1/1; (2) the two benzene rings of ace-DB20C6 fold around Cs above the center of the crown ether ring of ace-DB20C6.


真空加熱による粘土鉱物からのセシウム脱離挙動; 放射光を用いたX線光電子分光法及び昇温脱離法による分析

平尾 法恵; 下山 巖; 馬場 祐治; 和泉 寿範; 岡本 芳浩; 矢板 毅; 鈴木 伸一

分析化学, 65(5), p.259 - 266, 2016/05

 被引用回数:4 パーセンタイル:20.01(Chemistry, Analytical)

福島原子力発電所事故後の放射能汚染の主な原因であるCsは土壌中の粘土鉱物に強く固定されており、土壌除染のため様々なCs除去法が開発されている。本手法は、乾式法によるCs除去法として、乾式法における処理温度の低減を目的とし、真空溶融塩処理法を提案する。非放射性Csを飽和収着させたバーミキュライトを真空加熱し、X線光電子分光法を用いて加熱前後のCs含有量変化を分析した。バーミキュライトのみを用いた場合は、800$$^{circ}$$C 3分間の加熱で約4割のCsが除去された。NaCl/CaCl$$_{2}$$混合塩をバーミキュライトに添加した場合は、450$$^{circ}$$C 3分間の加熱で約7割のCsが除去されることを見いだした。これらの結果から真空溶融塩処理法による大幅な処理温度の低下と除去効率の向上が期待できる。


X-ray absorption fine structure at the cesium $$L$$3 absorption edge for cesium sorbed in clay minerals

本田 充紀; 下山 巖; 岡本 芳浩; 馬場 祐治; 鈴木 伸一; 矢板 毅

Journal of Physical Chemistry C, 120(10), p.5534 - 5538, 2016/03

 被引用回数:16 パーセンタイル:59.79(Chemistry, Physical)

We present the use of near-edge X-ray absorption fine structure (NEXAFS) to investigate local electronic structures of cesium ions sorbed in two types of clay minerals (vermiculite and kaolinite) with a different capacity to fix Cs. NEXAFS is element specific because X-ray absorption edges of different elements have different energies. However, the energy of the Cs $$L$$3 absorption edge is close to that of the $$K$$-edge of titanium generally contained in clay minerals. Therefore, Cs $$L$$3-edge NEXAFS measurements of Cs in clay minerals have not yet succeeded. In this study, we successfully measured pure Cs $$L$$3-edge NEXAFS spectra for cesium sorbed in clay minerals by completely separating Ti $$K alpha$$ and Cs $$L alpha$$ fluorescence X-rays using a fluorescence method. We confirmed the peak intensity between vermiculite and kaolinite in the NEXAFS spectra. To clarify the identification of NEXAFS spectra, theoretical calculations were performed using the discrete variational X$$alpha$$ molecular orbital method (DV-X$$alpha$$), and peak identification was achieved. The difference in peak intensity was explained by the difference in the electron density of unoccupied molecular orbitals. We studied the influence of water molecules and found a change in the electron densities of unoccupied molecular orbitals caused by the coordination of water molecules.


Development of fluorescence XAFS system in soft X-ray region toward operando conditions using polycapillary X-ray lens

本田 充紀; 下山 巖; 馬場 祐治; 鈴木 伸一; 岡本 芳浩; 矢板 毅

e-Journal of Surface Science and Nanotechnology (Internet), 14, p.35 - 38, 2016/02

We developed a fluorescence XAFS system toward operando conditions using soft X-ray radiation at KEK-PF BL-27A. X-ray adsorption fine structure (XAFS) analysis in the soft X-ray region is useful for elucidating molecular structures in both atmosphere and solutions. Particularly, light elements play an important role in many cases in this energy region. The attenuation of soft X-rays in a solution is large compared to that of hard X-rays. Thus, appropriate spectral statistics cannot be obtained in the soft X-ray region. Recently, using fluorescence XAFS measurement at the S K-edge (2.4 keV), we found that biological molecules containing sulfur atoms adopt specific molecular structures under different pH conditions in a solution. However, the diameter of the beam of this beam line at BL-27A was large, leading to difficulties in uniformly irradiating only the sample surface. Therefore, it was necessary to uniformly irradiate samples using a small-area X-ray beam. To collimate the beam and improve its intensity, we installed an X-ray focusing device. Herein, we introduce a light-collecting device that uses a polycapillary X-ray lens to focus soft X-rays. After installing this lens, we confirmed that focused X-rays and a higher-intensity beam were achieved. We conclude that focusing X-rays using a polycapillary lens in the soft X-ray region is an effective method for obtaining better spectral statistics in fluorescence XAFS measurements.

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