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論文

Optimized TES microcalorimeters with 14 eV energy resolution at 30 keV for $$gamma$$-ray measurements of the $$^{229}$$Th isomer

村松 はるか*; 林 佑*; 湯浅 直樹*; 紺野 良平*; 山口 敦史*; 満田 和久*; 山崎 典子*; 前畑 京介*; 菊永 英寿*; 滝本 美咲; et al.

Journal of Low Temperature Physics, 200(5-6), p.452 - 460, 2020/09

 被引用回数:0 パーセンタイル:100(Physics, Applied)

We have developed a four-pixel array of superconducting transition-edge sensors with gold absorbers for the detection of a 29.2 keV $$gamma$$-ray doublet decay from $$^{229}$$Th. To identify the decay, an energy resolution better than 20 eV full width at half maximum (FWHM) is needed. We measured an energy resolution of 14 eV FWHM for 26 keV $$gamma$$-ray decay from an $$^{241}$$Am isotope in combined data of three pixels. We describe the design and the performance of the devices and discuss the baseline correction method to compensate the variation in the baseline, which was observed during the evaluation of the performance using the $$^{241}$$Am isotope.

論文

Energy of the $$^{229}$$Th nuclear clock isomer determined by absolute $$gamma$$-ray energy difference

山口 敦史*; 村松 はるか*; 林 佑*; 湯浅 直樹*; 中村 圭佑; 滝本 美咲; 羽場 宏光*; 小無 健司*; 渡部 司*; 菊永 英寿*; et al.

Physical Review Letters, 123(22), p.222501_1 - 222501_6, 2019/11

 被引用回数:5 パーセンタイル:33.25(Physics, Multidisciplinary)

The low-lying isomeric state of $$^{229}$$Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by measuring the absolute energy difference between two $$gamma$$-decays from the 29.2-keV second-excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV $$gamma$$-ray with improved precision. Together with the cross-band transition energy (29.2 keV$$rightarrow$$ground) and the branching ratio of the 29.2-keV state measured in a recent study, the isomer energy was determined to be 8.30$$pm$$0.88 eV. Our result is in agreement with latest measurements based on different experimental techniques, which further confirms that the isomeric state of $$^{229}$$Th is in the laser-accessible vacuum ultraviolet range.

論文

Application of glutathione to roots selectively inhibits cadmium transport from roots to shoots in oilseed rape

中村 進一*; 鈴井 伸郎; 長坂 俊紀*; 小松 史弥*; 石岡 典子; 伊藤 小百合*; 河地 有木; 頼 泰樹*; 服部 浩之*; 茅野 充男*; et al.

Journal of Experimental Botany, 64(4), p.1073 - 1081, 2013/02

 被引用回数:38 パーセンタイル:12.51(Plant Sciences)

This study investigated the effects of the reduced form of glutathione (GSH) applied to specific organs (source leaves, sink leaves, and roots) on cadmium (Cd) distribution and behaviour in the roots of oilseed rape plants (${it Brassica napus}$) cultured hydroponically. The translocation ratio of Cd from roots to shoots was significantly lower in plants that had root treatment of GSH than in control plants. GSH applied to roots reduced the Cd concentration in the symplast sap of root cells and inhibited root-to-shoot Cd translocation via xylem vessels significantly. GSH applied to roots also activated Cd efflux from root cells to the hydroponic solution. Inhibition of root-to-shoot translocation of Cd was visualized, and the activation of Cd efflux from root cells was also shown by using a positron-emitting tracer imaging system (PETIS). This study investigated a similar inhibitory effect on root-to-shoot translocation of Cd by the oxidized form of glutathione, GSSG. Inhibition of Cd accumulation by GSH was abolished by a low-temperature treatment. Root cells of plants exposed to GSH in the root zone had less Cd available for xylem loading by actively excluding Cd from the roots. Consequently, root-to-shoot translocation of Cd was suppressed and Cd accumulation in the shoot decreased.

論文

Comparison of $$^{107}$$Cd absorption and accumulation between transgenic tobacco plants and control plants

中村 進一*; 鈴井 伸郎; 石井 里美; 河地 有木; 石岡 典子; 頼 泰樹*; 服部 浩之*; 茅野 充男*; 藤巻 秀

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 96, 2012/01

Phytoremediation is one of good technique to recover Cd from contaminated soils. To make this technique more effective, it is necessary to understand the mechanism of Cd dynamics and control them. It is known that Cd movement in the plant body is similar to zinc (Zn) movement. However, these mechanisms are not fully understood so far. In this work, we compared Cd absorption and accumulation between control tobacco plants and transgenic tobacco plants, which were transform with zinc transporter genes, by using positron emitting tracer imaging system (PETIS) and $$^{107}$$Cd. We succeeded to obtain fine serial images of Cd absorption and accumulation in tobacco plants, but there was no difference in Cd absorption and accumulation between transgenic tobacco plants and control plants. In previous experiments using non-radioactive Cd, Cd content in transgenic plants was 1.2 times higher than that in control plants. However, the PEITIS results indicated that such differences were not identified clearly in serial images obtained by PETIS experiments. Because PETIS experiments were performed in low Cd condition (0.1 $$mu$$M), we supposed that Cd concentration might have a significant impact on these results.

論文

Visualization of $$^{107}$$Cd accumulation in oilseed rape plants treated with glutathione

中村 進一*; 鈴井 伸郎; 伊藤 小百合*; 河地 有木; 石岡 典子; 頼 泰樹*; 服部 浩之*; 茅野 充男*; 藤巻 秀

JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 104, 2011/01

Glutathione (GSH) is involved in many aspects of metabolism. In our previous work, GSH concentration in the phloem sap collected from oilseed rape plants increased by Cd treatment. These results suggested that GSH might be playing important roles in controlling Cd long-distance transport and accumulation in plants. In this work, we investigated effects of GSH to Cd long-distance transport and accumulation by using positron emitting tracer imaging system (PETIS). After setting two week old oilseed rape plants in the chamber, PETIS experiments were started by adding purified $$^{107}$$Cd in the nutrient solutions which were including GSH. As a result, we succeeded to obtain images of $$^{107}$$Cd accumulation in these plants. $$^{107}$$Cd signals were observed in the shoot and root of oilseed rape plants. In the shoot, Cd accumulation was inhibited by GSH treatment. However, we could not see any difference in the Cd accumulation in the root of oilseed rape plants. Further research enables us to understand effects of GSH on Cd long-distance transport and accumulation.

論文

Tracing cadmium from culture to spikelet; Noninvasive imaging and quantitative characterization of absorption, transport, and accumulation of cadmium in an intact rice plant

藤巻 秀; 鈴井 伸郎; 石岡 典子; 河地 有木; 伊藤 小百合; 茅野 充男*; 中村 進一*

Plant Physiology, 152(4), p.1796 - 1806, 2010/02

 被引用回数:136 パーセンタイル:2.16(Plant Sciences)

We characterized the absorption and translocation of cadmium (Cd) in rice using serial images observed with a positron-emitting tracer imaging system (PETIS). We fed a positron-emitting $$^{107}$$Cd tracer to the hydroponic culture. The absorption rates by the root were proportional to Cd concentrations in the culture within the tested range below 100 nM. It was estimated that the radial transport from the culture to the xylem in the root tissue was completed in less than 10 min. Cd moved up through the shoot with velocities of a few centimeters per hour, which was obviously slower than the bulk flow in the xylem. Cd reached the panicles 7 h after feeding and accumulated there constantly. The nodes exhibited the most intensive Cd accumulation in the shoot and Cd transport from the basal nodes to crown root was observed. We concluded that the nodes are the central organ where xylem-to-phloem transfer occurs and play a pivotal role in the half-day travel of Cd from the soil to the grains.

論文

Kinetic analysis of cadmium uptake in oilseed rape plants using positron multi-probe system

鈴井 伸郎; 中村 進一*; 伊藤 小百合; 河地 有木; 石岡 典子; 藤巻 秀

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 102, 2009/12

We have developed a monitoring system of $$^{107}$$Cd radioactivity in tracer solution using Positron Multi-Probe System (PMPS) that enables the noninvasive measurement of the amounts of $$^{107}$$Cd uptake by an intact plant. Two-week old oilseed rape plant (${it Brassica napus}$ L.) was placed into a plastic cylindrical container containing 30 ml of 0.5 mM CaCl$$_{2}$$ solution with approximately 10 MBq of $$^{107}$$Cd. The cylindrical container was divided by nylon mesh into two compartments, the root of the plant was immersed in the upper compartment, and a pair of PMPS detectors was placed outside the bottom compartment. As a result, we successfully obtained the continuous data of the amount of a radioactive tracer taken up by the intact plant for 36 hours.

論文

Visualization of $$^{107}$$Cd translocation in Tobacco plants

中村 進一*; 鈴井 伸郎; 石岡 典子; 河地 有木; 伊藤 小百合; 服部 浩之*; 茅野 充男*; 藤巻 秀

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 103, 2009/12

Tabacco plant is one of model plants which enable us to manipulate its gene expression, it is expected to create crop plants with low Cd content in the future. In this study, we visualized Cd dynamics in tobacco plant. Tobacco plants (${it Nicotiana tabacum}$) were grown hydroponically in a growth chamber where the growth conditions of plants were controlled completely for two weeks after sowing. After setting plants in the chamber, PETIS experiments were started by adding purified $$^{107}$$Cd in nutrient solutions. Time-series images of the $$^{107}$$Cd distribution were obtained with the PETIS apparatus. Each image was obtained every four minute for 36 hours. We succeeded to obtain fine serial images of Cd transport and accumulation in tobacco plants. Strong $$^{107}$$Cd signals were observed in the roots of tobacco plants. We also could see strong signals of $$^{107}$$Cd in the stems. In leaves, $$^{107}$$Cd signals were distributed thoroughly. The pattern of Cd signal distribution in the tobacco plants was similar to that in oilseed plants). These results demonstrated that dicotyledonous plants had the similar pattern of Cd distribution when plants were treated at low concentration of Cd.

論文

Non-invasive imaging of carbon translocation and nitrogen fixation in intact plants using the positron-emitting tracer imaging system

鈴井 伸郎; 石井 里美; 河地 有木; 伊藤 小百合; 中村 進一*; 石岡 典子; 藤巻 秀

Proceedings of 16th International Plant Nutrition Colloquium (IPNC-16) (Internet), P. 1214, 2009/04

We developed analytical methods for monitoring carbon translocation and nitrogen fixation in intact plants using short-lived radioactive tracer gases and the positron-emitting tracer imaging system (PETIS). In the analysis of carbon translocation, we fed $$^{11}$$C (half life: 20.4 min)-labeled radioactive carbon dioxide gas to leave blades of rice plants, and serial images of $$^{11}$$C-photoassimilate were obtained non-invasively using PETIS. In order to understand source-sink relations, we manipulated source and sink strength by treating tested rice plants with p-chlorobenzenesulfonic acid (PCMBS), an inhibitor of sucrose transporters. As a result, a decrease in the velocity after the manipulation was successfully detected. In the analysis of nitrogen fixation, we newly developed a rapid method to produce and purify $$^{13}$$N (half life: 10.0 min)-labeled radioactive nitrogen gas and fed the gas to the underground part of nodulated soybean plants. As a result, obvious signal of $$^{13}$$N was observed at the nodules.

論文

Non-invasive imaging and characterization of absorption, transport and accumulation of cadmium in an intact rice plant

藤巻 秀; 鈴井 伸郎; 石岡 典子; 河地 有木; 伊藤 小百合; 茅野 充男*; 中村 進一*

Proceedings of 16th International Plant Nutrition Colloquium (IPNC-16) (Internet), 1 Pages, 2009/04

カドミウム107トレーサの製造法を開発し、ポジトロンイメージングを用いて、栄養成長期及び生殖成長期のイネにおけるカドミウムの輸送動態を定量的に解析した。その結果、土壌から玄米に至る過程において導管から篩管への乗り換えが重要なステップであり、それが節で行われていることを推定した。

論文

Non-invasive imaging of cadmium distribution in intact oilseed rape plants

中村 進一*; 鈴井 伸郎; 石岡 典子; 河地 有木; 伊藤 小百合; 頼 泰樹*; 服部 浩之*; 茅野 充男*; 藤巻 秀

Proceedings of 16th International Plant Nutrition Colloquium (IPNC-16) (Internet), p.1181_1 - 1181_2, 2009/04

Reduction of cadmium (Cd) accumulation in farm products has become more and more important in order to produce them in a safe and sustainable manner. It is necessary to elucidate mechanisms of Cd distribution in plants. However, these mechanisms are not fully understood. The purpose of our work is to clarify these mechanisms by visualizing Cd absorption, transport and accumulation non-invasively using positron-emitting tracer imaging system (PETIS). $$^{107}$$Cd (half-life: 6.5 hr) was used as a positron-emitting tracer in the PETIS experiments. We succeeded to obtain serial images of cadmium distribution in oilseed rape plants ($$it{Brassica napus}$$ L.). Strong $$^{107}$$Cd signals were observed in the basal region of the shoot. We also could see strong signals in the node of oilseed rape plants. Cd distribution in oilseed rape plants will be discussed quantitatively using the results from PETIS experiments.

論文

Imaging of $$^{107}$$Cd translocation in oilseed rape plants treated with different Cd concentrations

鈴井 伸郎; 藤巻 秀; 石岡 典子; 河地 有木; 松橋 信平; 服部 浩之*; 茅野 充男*; 中村 進一*

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 112, 2008/11

Cadmium (Cd) is one of toxic heavy metal element. In order to decrease Cd accumulation in these products, it is necessary to elucidate mechanisms of Cd long-distance transport in the plant body. In this research, we tried to elucidate mechanisms of Cd long-distance transport by visualizing Cd transport in the plant body using positron emitting tracer imaging system (PETIS) and $$^{107}$$Cd. Oilseed rape plants (Brassica napus L.) were grown hydroponically for two weeks after sowing. In this PETIS experiment, different concentrations of Cd (0.1 $$mu$$M and 10 $$mu$$M) were added as a carrier to hydroponic solutions. 0.1 $$mu$$M is comparable to the Cd concentration in the soil solution from non Cd-polluted soils. 10 $$mu$$M is comparable to the toxic Cd concentration for oilseed rape plants. As a result, the pattern of Cd accumulation in the oilseed rape plants was similar in the different Cd concentrations (0.1 $$mu$$M and 10 $$mu$$M). These results indicate that in early stages, Cd concentration in the hydroponic solution do not have effects on Cd absorption in the root systems.

論文

土壌中からのカドミウムの除去技術(ファイトレメディエーション)の実用化を目指した研究におけるポジトロンイメージング技術の貢献

中村 進一*; 茅野 充男*; 藤巻 秀; 鈴井 伸郎; 石岡 典子; 河地 有木; 松橋 信平

放射線と産業, (117), p.9 - 14, 2008/03

食の安全を脅かす要因の一つに、人体にとって有害な物質であるカドミウムの農作物への蓄積がある。農作物へのカドミウムの蓄積を抑制するためには、高等植物におけるカドミウムの長距離輸送機構を解明し、それらを制御する必要がある。しかし、これまでの研究では植物におけるカドミウムの長距離輸送のメカニズムは十分に明らかになっていない。そこでわれわれは、プラナー型ポジトロン放出核種画像化システム(PETIS)を用いて、高等植物におけるカドミウムの吸収・移行・蓄積の動態を画像化し、それらを解析することにより、その機構の解明を目指した。本稿では本研究における近年の成果について報告する。

論文

Non-invasive imaging of cadmium long-distance transport in higher plants

中村 進一*; 鈴井 伸郎; 石岡 典子; 河地 有木; 茅野 充男*; 松橋 信平; 藤巻 秀

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 123, 2008/03

Cadmium (Cd) is a harmful heavy metal element. In order to decrease the cadmium content in the farm products, it is necessary to elucidate the mechanism of transport of Cd in the plant body. In this research, we visualized Cd transport in the plant body by using Positron Emitting Tracer Imaging System (PETIS) and $$^{107}$$Cd. We tried to elucidate the mechanism of Cd transport in the whole plants by analyzing the experimental data which is obtained by PETIS. We could observe that $$^{107}$$Cd signals arrive in the aerial parts of both plants in a few hours after the start of the experiment. Patterns of accumulation of $$^{107}$$Cd signals in sorghum plants were similar to those in rice plants. Strong signals of $$^{107}$$Cd were seen in the basal region of the shoot, which consists of a short stem, nodes and meristems. Interestingly, $$^{107}$$Cd also accumulated in the node strongly in oilseed rape plants although these two plants have different structure as a monocot and a dicot.

論文

Non-invasive imaging of cadmium transport in crop plants

藤巻 秀; 中村 進一*; 鈴井 伸郎; 石岡 典子; 茅野 充男*; 松橋 信平

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 127, 2007/02

イネ,ソルガムなどを供試植物とし、生きた植物体におけるカドミウムの吸収・移行・蓄積の様子をPositron Emitting Tracer Imaging System(PETIS)を用いて非侵襲的・経時的・定量的に画像化する技術を確立した。

論文

Improved separation of cadmium-107 from silver cyclotron targets by precipitation method

石岡 典子; 藤巻 秀; 鈴井 伸郎; 中村 進一*; 松橋 信平

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 162, 2007/02

植物におけるカドミウムの吸収・分配機構を解明するためのトレーサとして、荷電粒子反応を用いたCd-107の製造法の改良を行った。照射済みのAgターゲットを硝酸により溶解した後、塩酸をグラジエント方式により加え、AgCl沈殿からCd-107を分離した。グラジエント方式により得られたCd-107の分離効率は、93%であった。グラジエント方式は分離効率の向上に加え、塩酸注入時間の短縮にも有効である。開発したCd-107は、ポジトロンイメージング装置により植物におけるカドミウム動態のリアルタイム計測が可能で、近年問題視されている農作物中のカドミウムの吸収・分配機構を解明するためのトレーサとして有用である。化学分離法の改良により、迅速で高回収率な放射性カドミウムトレーサの製造に成功した。

論文

Quasi-two dimensional electronic state of the antiferromagnet UPtGa$$_5$$

池田 修悟; 常盤 欣文*; 芳賀 芳範; 山本 悦嗣; 大久保 智幸*; 山田 美音子*; 中村 仁子*; 杉山 清寛*; 金道 浩一*; 稲田 佳彦*; et al.

Journal of the Physical Society of Japan, 72(3), p.576 - 581, 2003/03

 被引用回数:41 パーセンタイル:16.18(Physics, Multidisciplinary)

反強磁性UPtGa$$_5$$のフェルミ面の特徴を明らかにするためにドハース・ファンアルフェン(dHvA)効果測定を行った。また高磁場磁化測定から磁気相図を明らかにした。dHvA実験からフェルミ面は、正方晶の[001]方向に長い4つの準2次元的なフェルミ面から形成されていることがわかった。この結果は、反強磁性構造を考慮に入れたバンド計算の結果とほぼ一致している。また10~24m$$_0$$ ($$m_0$$ : 電子の静止質量)の比較的大きなサイクロトロン有効質量を観測した。

論文

Single crystal growth and structural and magnetic properties of the uranium thernary intermetallic compound UCr$$_2$$Si$$_2$$

松田 達磨; 目時 直人; 芳賀 芳範; 池田 修悟; 大久保 智幸*; 杉山 清寛*; 中村 仁子*; 金道 浩一*; 金子 耕士; 中村 彰夫; et al.

Journal of the Physical Society of Japan, 72(1), p.122 - 130, 2003/01

 被引用回数:10 パーセンタイル:43.27(Physics, Multidisciplinary)

われわれは、UCr$$_2$$Si$$_2$$の単結晶育成を初めて行なった。この物質について、温度約210K において高温の正方晶から三斜晶への構造相転移を示すことを明らかにした。また中性子回折実験によって低温における磁気構造を決定した。低温高磁場磁化測定ではメタ磁性転移が11.4Tで起きることを明らかにし、比熱測定からは電子比熱係数が約80mJ/K$$^2$$molと比較的重い電子系化合物であることを明らかにした。

論文

Rock-like oxide fuels and their burning in LWRs

山下 利之; 蔵本 賢一; 秋江 拓志; 中野 佳洋; 白数 訓子; 中村 武彦; 草ヶ谷 和幸*; 大道 敏彦*

Journal of Nuclear Science and Technology, 39(8), p.865 - 871, 2002/08

 被引用回数:25 パーセンタイル:15.92(Nuclear Science & Technology)

余剰プルトニウムの効率的な利用と廃棄のための新しいオプションを提案するため、岩石型プルトニウム燃料とその軽水炉中での燃焼技術に関する研究を行った。岩石型燃料はイナートマトリクス燃料の一種で、安定化ジルコニア,スピネルやコランダムなどの鉱物類似化合物から構成される。重核分裂片による照射損傷を軽減するため、粒子分散型燃料を考案した。照射試験により、スエリング,ガス放出,微細組織変化に関する知見が得られた。岩石型プルトニウム燃料装荷炉心が有する本来的な短所は、ウランやトリウムなどの共鳴物質を添加することで改善され、改善炉心の過渡時における特性は通常の軽水炉炉心と同等となった。反応度事故条件下における岩石型燃料棒の破損しきい値は軽水炉燃料と同等であることが、パルス照射試験により確認された。

論文

Current status of researches on the plutonium rock-like oxide fuel and its burning in light water reactors

山下 利之; 秋江 拓志; 中野 佳洋; 蔵本 賢一; 二谷 訓子; 中村 武彦

Progress in Nuclear Energy, 38(3-4), p.327 - 330, 2001/02

 被引用回数:12 パーセンタイル:32.76(Nuclear Science & Technology)

余剰プルトニウムの軽水炉での燃焼を目的とする岩石型プルトニウム燃料概念を発展させた。不活性マトリックスの基礎物性と岩石型燃料の照射挙動の研究から、有望な燃料候補として粒子分散型燃料を開発した。本燃料とPuO$$_{2}$$と種々の添加物を固溶したイットリア安定化ジルコニア(YSZ)球状粒子をスピネルマトリックス中に均質に分散させたものである。また、既存計算コードによる安全性解析やNSRRでの反応度事故実験から、YSZとスピネルから成る岩石型燃料は現行UO$$_{2}$$燃料に匹敵する安全性を有することがわかった。これらに加えて、粒子分散型燃料の製造や照射試験に関する最近の成果をまとめた。

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