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横山明彦, 太田宏次監修
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横山明彦著
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研究代表者:横山明彦
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奥村浩士 [ほか] 編
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田崎, 和江 ; 中西, 孝 ; 横山, 明彦 ; Tazaki, Kazue ; Nakanishi, Takashi ; Yokoyama, Akihiko
概要:
金沢大学理工研究域地球社会基盤学系
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田崎, 和江 ; 竹原, 照明 ; 橋田, 由美子 ; 橋田, 省三 ; 中村, 圭一 ; 横山, 明彦 ; 青木, 小波 ; 田崎, 史江 ; Tazaki, Kazue ; Takehara, Teruaki ; Hashida, Yumiko ; Hashida, Shozo ; Nakamura, Keiichi ; Yokoyama, Akihiko ; Aoki, Conami ; Tazaki, Fumie
概要:
金沢大学理工研究域地球社会基盤学系<br />黒柿はカキノキ科の一つであり，幹・枝・根の断面に黒色の部分があり，心材や辺材には縞が美しい孔雀の羽根のような模様（孔雀杢 くじゃくもく）がある．孔雀杢は何百年と樹齢を重ね，かつ，様々な条件を満た
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した柿の木だけが黒と白の美しい模様を持つようになった希少な銘木である．材質が竪硬で粘りもあり，細かい細工をする指物に適しており和家具，茶道具などが金沢伝統工芸品となっている．しかし，江戸時代に加賀藩が黒柿の栽培を行っていたとされるものの，その科学的な記録はない．なぜ柿の木の幹に黒い色の美しい模様ができるのかを究明するために，石川県金沢市内に生育している黒柿を採取して，IP，XRD，ICP-MS，XRF，SEM-EDS，放射能測定器を用いて物理化学的，鉱物学的，微生物学的特徴を調べた．本研究試料の「黒柿」のXRD 分析では，セルロースの他に低温型α- クリストバライト，生体アパタイト（燐灰石），ハロイサイトなどの粘土鉱物が含まれていた．黒柿の黒色化した幹に形成する孔雀杢は“珪化木”ということができる．本研究結果から，①黒柿が“珪化木”になるには，まず，根の中心の白色部に認められた微生物がCa >>> P，S >> Mg > Si，Fe，Cl，K，Mn を取り込み，生体アパタイトを形成する．②成長するにしたがって，放射能核種やB，Br を伴って, さらにCa，P，S >> K，Mg，Si，Sr > Cl，Mn，Fe などの元素を取り込みながら黒色化する．③そして，年月を経るにしたがって, 幹の辺材部に黒色の縞模様（孔雀杢）を作りながら低温型α- クリストバライト（珪化木）を形成することが明らかになった．<br />Kurogaki (Black persimmon; Diospyros kaki) grows very slowly and has extremely hard wood known for its striking black coloration, referred to as the “peacock pattern”. It was formerly planted in Kanazawa, Ishikawa, Japan. Kurogaki is currently very rare, found in only one of every 1,000 to 10,000 trees. Therefore, scientific data on Kurogaki are currently very limited but these trees are highly valuable for manufacturing furniture, tea ceremony goods, boxes, and other miscellaneous articles.Here we report the characterization of Kurogaki at Kanazawa, Ishikawa, Japan, based on radioactivity, purple mineral light, and H2 O2 reactions in the field. To date, no report has described the results of electron microscopy observations and chemical analyses, which could elucidate simple identification of species. Here we studied the microstructure, mineralogy, chemical composition, and radioactivity associated with microorganisms in Kurogaki wood using analytical data based on X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), imaging plate (IP), scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and semiconductor detectors. We investigated the distribution, location, identification, structure, and differentiation of the black “peacock pattern” parts and ordinarily colored wooden parts and roots.We evaluated the mineralogy, chemistry, and micromorphology of Kurogaki using a combination of micro techniques. Using XRD, the black “peacock pattern” parts were found to mainly comprise cellulose associated with spherical and beaded microorganisms, mineralized living apatite, α-cristobalite, and halloysite. Particular elements associated with microorganisms were identified using SEM-EDS, which revealed the elemental content maps of the central white spot in cross sections of the “peacock pattern”, indicating high concentrations of Ca, P and S. The chemical compositions of the black and white parts were determined based on mineralogical and chemical data obtained using XRF analyzer and ICP-MS.Furthermore, we used imaging plate methods to obtain radioactive images of the cross sections of the “peacock pattern”. The objective was to illustrate the association of minerals with various microorganisms that are capable of absorbing both radionuclides and stable isotopes from soil and water. A radio dosage analysis of the higher black parts was performed by imaging plate pictures. We investigated the quantitative radiation dosages of the “peacock pattern” using Ge and Si semiconductor detectors, which revealed 137Cs concentrations.The black “peacock pattern” parts were richer in almost all elements such as K, Ca, Mg, S, Al, Fe, P, Na, Mn, B and Ba, than the white cellulose parts, indicating a role of microorganisms in mediating the transfer of metal solutes from the hydrosphere and soils. Using SEM-EDS micromorphology, the chemical composition of the black “peacock pattern” parts was found to be associated with α-cristobalite and living apatite having wooden clapper-like microcrystals. The distribution of elements indicated the influences of soils in their surrounding environment. Our results provide the evidence of the ability of microorganisms to immobilize radionuclides in the soils. The microorganisms grow in the black “peacock pattern” parts of Kurogaki.In conclusion, α-cristobalite and living apatite crystals physically and biologically grow in the sap with cellulose under neutral conditions (pH7) in association with microorganisms using carbon dioxide supplied by bacteria. Therefore, the crystals produced the “peacock pattern” in Kurogaki were formed at late times during the year.
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田崎, 和江 ; 野村, 正純 ; 森井, 一誠 ; 佐藤, 和也 ; 馬場, 奈緒子 ; 中西, 孝 ; 横山, 明彦 ; Chaerun, Siti Khodijah ; Tazaki, Kazue ; Nomura, Masazumi ; Morii, Issei ; Satoh, Kazuya ; Baba, Naoko ; Nakanishi, Takashi ; Yokoyama, Akihiko
概要:
金沢大学理工研究域地球社会基盤学系<br />The magnitude-6.8 Chuetsu-Oki Earthquake struck at 10:13 a.m. 16th July 2007, off the northwester
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n coast of Japan in Niigata Prefecture, Japan. The hypocenter was Chuetsu-Oki region 37.33N, 138.36E (17km in depth). The quake started under the ocean about 9km North of Kashiwazaki Kariwa nuclear plant, killing 11 peoples, and flattening several hundreds of buildings. In this study, Radon has measured in air and ground fissures using portable natural gamma ray system on July 16-17, and 20-21th, 2007. The quite high gamma ray of 300-340 cpm was detected on July 21th at Ohminato, Kariwa village which is the nearest of the fault fissure zone. The abnormal increase (200-300cpm) was detected at large deep subsidence and new crack on the paved road. For comparison, normal air radon without earthquake was counted as low as 60-80cpm. The car-borne and hand-borne measurement system was assembled for easily and rapidly detecting full features of the fissures buried in the ground.
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中西, 孝 ; 横山, 明彦 ; 田崎, 和江 ; 小村, 和久 ; 山本, 政儀 ; 井上, 睦夫 ; 濱島, 靖典 ; 上杉, 正樹 ; 山田, 記大 ; 清水, 健彦
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横山, 明彦 ; Yokoyama, Akihiko
概要:
金沢大学理工研究域物質化学系<br />薄層クロマトグラフィーを利用したアスタチン化学種同定を通して、抽出挙動と化学形との関連について知見が得られ、アスタチンの酸化状態の重要性について定量的な考察ができるようになった。またラドンガス回収法を
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開発し、それと組み合わせたイオン液体系のアスタチン抽出ではアルカリ溶液でアスタチンを回収することで、ラドンの混入が最小限に抑えられ、ラドンとアスタチンの分離係数の高いシステムを構築できた。また副生成物であるポロニウムの除去についても、有用な陽イオン交換樹脂系を見出せたので、この研究でジェネレータのプロトタイプ作成が可能になった。<br />Present study using a TLC chromatography enabled us to analyze At species and know its correlation to extraction behaviors. It underlines the importance of oxidation states of At based on a quantitative discussion. A radon-gas storage method was devised in this study to construct an isolation process between radon and astatine by using extraction into ion liquid with a high separation factor, that is, least contamination of radon. Removal of polonium, a by-product of radon was also made possible with a cation-exchange resin. The study enables one to construct a proto-type generator of astatine from its parent nuclide of radon.<br />研究課題/領域番号:17K05807, 研究期間(年度):2017-04-01 – 2020-03-31<br />出典：「アスタチン・ジェネレータシステム構築のための放射性ラドンの化学」研究成果報告書 課題番号17K05807（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-17K05807/17K05807seika/)を加工して作成
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横山, 明彦 ; Yokoyama, Akihiko
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ラザホージウム(Ｒｆ)の4価イオンの挙動確認のため、キレート抽出剤ＴＴＡを保持した逆相クロマトグラフィー系の構築を試みた。このためにTTA樹脂を作成し、その吸着能について無担体放射性トレーサーを用いてまずはバッチ法で調べ、ついで樹脂を詰めた
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カラムを用いてオンライン実験において短寿命トレーサーによるRf模擬実験を実施した。その結果、平衡時間が速く吸着性のある樹脂の製造に成功し、またZrとHfの溶離曲線をフッ酸/硝酸の混酸系で得られたが、オンラインでの平衡状態は達成されていない。すでにRf実験も実施し、樹脂に吸着することが示唆される結果を得たが、解析はまだ途中で最終的な結論には至っていない。<br />In order to elucidate relevant chemical species of Rf by means of reversed-phase extraction chromatography with 2-thenoyltrifluoroacetone (TTA) as a stationary phase, we measured the equilibration time and distribution ratios in extraction by batch method experiments with carrier-free radiotracers of Zr and Hf on TTA-resin in the HF/HNO3 solutions and optimized an appropriate experimental condition for Rf. An online experiment has been also performed for the reversed-phase chromatographic behaviors of Zr and Hf on the TTA resin to simulate the Rf experiments. The elution curves from columns with the resin in the on-line experiment using Zr and Hf short-lived isotopes were obtained to show the effective adsorption with TTA although the equilibrium has not been attained, yet. The Rf atoms appears to be adsorbed to TTA in the on-line experiment with Rf, but the analysis is still on the way to deriving conclusive results.<br />研究課題/領域番号:23550070, 研究期間(年度):2011-2013
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