Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 30

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Design for detecting recycling muon after muon-catalyzed fusion reaction in solid hydrogen isotope target

Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09

A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 $$mu$$s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion ($$mu$$CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after $$mu$$CF reaction.

Journal Articles

Time evolution calculation of muon catalysed fusion; Emission of recycling muons from a two-layer hydrogen film

Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 169, p.112580_1 - 112580_5, 2021/08

A muon ($$mu$$) having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion between deuteron (d) and triton (t). These two nuclei are bound by $$mu$$ and form a muonic hydrogen molecular ion, dt$$mu$$. Due to the short inter-nuclear distance of dt$$mu$$, the nuclear fusion, d +t$$rightarrow alpha$$ + n + 17.6 MeV, occurs inside the molecule. This reaction is called muon catalyzed fusion ($$mu$$CF). Recently, the interest on $$mu$$CF is renewed from the viewpoint of applications, such as a source of high-resolution muon beam and mono-energetic neutron beam. In this work, we report a time evolution calculation of $$mu$$CF in a two-layered hydrogen isotope target.

Journal Articles

Preferential elimination of Ba$$^{2+}$$ through irreversible biogenic manganese oxide sequestration

Tani, Yukinori*; Kakinuma, Satomi*; Chang, J.*; Tanaka, Kazuya; Miyata, Naoyuki*

Minerals (Internet), 11(1), p.53_1 - 53_14, 2021/01

 Times Cited Count:0 Percentile:0.03(Geochemistry & Geophysics)

In this study, we examined the Ba$$^{2+}$$ sequestration potential of enzymatically active biogenic Mn oxides (BMOs) with and without exogenous Mn$$^{2+}$$. The BMOs readily oxidized exogenous Mn$$^{2+}$$ to produce another BMO phase, and subsequently sequestered Ba$$^{2+}$$ at a pH of 7.0, with irreversible Ba$$^{2+}$$ sequestration as the dominant pathway. Extended X-ray absorption fine structure spectroscopy and X-ray diffraction analyses demonstrated alteration from turbostratic to tightly stacked birnessite through possible Ba$$^{2+}$$ incorporation into the interlayer.

Journal Articles

Sequestration and oxidation of Cr(III) by fungal Mn oxides with Mn(II) oxidizing activity

Suzuki, Ryohei*; Tani, Yukinori*; Naito, Hirotaka*; Miyata, Naoyuki*; Tanaka, Kazuya

Catalysts, 10(1), p.44_1 - 44_15, 2020/01

 Times Cited Count:3 Percentile:42.88(Chemistry, Physical)

We prepared biogenic Mn oxides (BMOs) using ${it Acremonium strictum}$ strain KR21-2, and subsequently conducted single or repeated treatment experiments in Cr(NO$$_{3}$$)$$_{3}$$ at pH6.0. Under aerobic conditions, newly formed BMOs exhibited a rapid production of Cr(VI) without a significant release of Mn(II), demonstrating that newly formed BMO mediates a catalytic oxidation of Cr(III) with a self-regeneration step of reduced Mn. In anaerobic solution, newly formed BMOs showed a cessation of Cr(III) oxidation in the early stage of the reaction, and subsequently had a much smaller Cr(VI) production with significant release of reduced Mn(II).

Journal Articles

Quantitative micro-X-ray fluorescence scanning spectroscopy of wet sediment based on the X-ray absorption and emission theories; Its application to freshwater lake sedimentary sequences

Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*

Sedimentology, 66(6), p.2490 - 2510, 2019/10

 Times Cited Count:2 Percentile:39.34(Geology)

Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.

Journal Articles

Adsorption of Cs onto biogenic birnessite; Effects of layer structure, ionic strength, and competition cations

Yu, Q.*; Tanaka, Kazuya; Kozai, Naofumi; Sakamoto, Fuminori; Tani, Yukinori*; Onuki, Toshihiko

ACS Earth and Space Chemistry (Internet), 2(8), p.797 - 810, 2018/08

Most of Mn oxides are biogenic and known to adsorb cesium (Cs) on the surface. This study investigated structural transformation of biogenic birnessite by accommodating commonly occurring natural heavy metals (Zn, Ni) during the formation of Mn oxides and the influence of those metals on the adsorption behavior of Cs on Mn oxides. It was found that the presence of heavy metals during bio-oxidation of Mn(II), followed by exposure to a low pH aqueous solution, increased the number of available layer vacancies, which consequently increased the adsorption capacity of Cs in the final product birnessite.

Journal Articles

Hydrological and climate changes in southeast Siberia over the last 33 kyr

Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.

Global and Planetary Change, 164, p.11 - 26, 2018/05

 Times Cited Count:6 Percentile:46.34(Geography, Physical)

Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.

Journal Articles

Fungus-promoted transformation of lanthanides during the biooxidation of divalent manganese

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya; Kozai, Naofumi; Yamasaki, Shinya*; Sakamoto, Fuminori; Tani, Yukinori*

Geochimica et Cosmochimica Acta, 174, p.1 - 12, 2016/02

 Times Cited Count:15 Percentile:65.4(Geochemistry & Geophysics)

Although microorganisms possess high sorption capability for lanthanides (Lns), their biological response affecting Lns migration is unclear. We investigated the effects of microbial activity on transformation of Lns by contact of Lns with Aeremonium strictum under metabolically active condition with Mn(II). A biomolecule that specifically complex to Ce(IV) was found to be released from the fungal cell, facilitating the desorption of Ce(IV) from Mn oxide. This biomolecule was not associated with any other trivalent Lns or Fe, which differed from those non-nuclide-specific organic substances released from resting cells, as reported previously.

Journal Articles

Specific sorption behavior of actinoids on biogenic Mn oxide

Tanaka, Kazuya*; Tani, Yukinori*; Onuki, Toshihiko

Chemistry Letters, 40(8), p.806 - 807, 2011/08

 Times Cited Count:7 Percentile:32.68(Chemistry, Multidisciplinary)

We made sorption experiments of actinides on Mn oxide in dilute NaCl solution. Sorption affinity of actinides on synthetic Mn oxide was Th(IV) $$>$$ U(VI) $$>$$ Np(V). The specific sorption behavior of actinides on biogenic Mn oxide was observed. Thorium sorbed on biogenic Mn oxide was desorbed into solution with increasing time. Neptunium was not sorbed on biogenic Mn oxide. The specific sorption behavior is possibly due to organic ligands released from microorganisms and surface property of biogenic Mn oxide.

Journal Articles

A Specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp. strain KR21-2

Tanaka, Kazuya; Tani, Yukinori*; Takahashi, Yoshio*; Tanimizu, Masaharu*; Suzuki, Yoshinori*; Kozai, Naofumi; Onuki, Toshihiko

Geochimica et Cosmochimica Acta, 74(19), p.5463 - 5477, 2010/10

 Times Cited Count:67 Percentile:87.41(Geochemistry & Geophysics)

We carried out sorption experiments of Ce by biogenic Mn oxide produced by a Mn(II)-oxidizing fungus strain KR21-2. The results of the sorption experiments indicated that Ce(III) was oxidized to Ce(IV) by biogenic Mn oxide in solution with pH 3.8 - 7. Furthermore, oxidized Ce(IV) by biogenic Mn oxide was complexed with organic ligands released from fungal cells under circumneutral conditions.

Journal Articles

Interaction of inorganic arsenic with biogenic manganese oxide produced by a Mn-oxidizing fungus, strain KR21-2

Tani, Yukinori*; Miyata, Naoyuki*; Ohashi, Maiko*; Onuki, Toshihiko; Seyama, Haruhiko*; Iwahori, Keisuke*; Soma, Mitsuyuki*

Environmental Science & Technology, 38(24), p.6618 - 6624, 2004/12

 Times Cited Count:76 Percentile:83.48(Engineering, Environmental)

no abstracts in English

Oral presentation

Ce oxidation by Mn oxide produced by Acremonium sp. strain KR21-2

Tanaka, Kazuya; Tani, Yukinori*; Onuki, Toshihiko

no journal, , 

no abstracts in English

Oral presentation

Specific oxidation process of Ce(III) by Mn-oxidizing fungus strain KR21-2

Tanaka, Kazuya; Tani, Yukinori*; Onuki, Toshihiko

no journal, , 

no abstracts in English

Oral presentation

Development of negative Ce anomalies in biogenic Mn oxide; The Role of microorganism on REE mobility during the bio-oxidation of Mn$$^{2+}$$

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Yamasaki, Shinya; Sakamoto, Fuminori; Tani, Yukinori*

no journal, , 

Oral presentation

Adaptive interactions between Live Acremonium strictum KR21-2 Fungus and REEs during Mn(II) bio-oxidation

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Yamasaki, Shinya*; Sakamoto, Fuminori; Tani, Yukinori*

no journal, , 

REEs were accumulated by MnO$$_{2}$$ during oxidation of Mn(II) to MnO$$_{2}$$ by manganese oxidizing fungus. In the presence of citate-Na, adsorption of REE was lowered than that without citrate. REE pattern in the solution showed positive anomaly in Ce, indicating that Ce(IV) was associated with organic materials excreted from the cells.

Oral presentation

Fungus activity promoted transformation of REEs during bio-oxidation of Mn(II)

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Sakamoto, Fuminori; Tani, Yukinori*

no journal, , 

Oral presentation

Effect of live acremonium strictum KR21-2 fungus on the mobility of REEs during the bio-oxidation of Mn(II)

Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Sakamoto, Fuminori; Tani, Yukinori*

no journal, , 

Oral presentation

Specific sorption processes of REEs and actinides induced by biomolecules

Tanaka, Kazuya; Tani, Yukinori*; Onuki, Toshihiko*

no journal, , 

We investigated sorption of rare earth elements (REEs) and actinides on biogenic Mn oxide. Sorption experiments of REEs showed a negative Ce anomaly under circumneutral conditions. SEC-HPLC-ICP-MS analysis confirmed that Ce was complexed with organic ligands in solution. A line of data indicates that the negative Ce anomaly under circumneutral pH conditions arose from Ce(III) oxidation on biogenic Mn oxide and subsequent complexation of Ce(IV) with biomolecules. Th(IV) was sorbed, and then desorbed from biogenic Mn oxide with time. The desorption of Th(IV) is possibly attributed to organic ligands released from fungal cells as observed in the Ce sorption. In contrast, sorption of Pu(IV) increased with time, which was similar to that of U(VI). Plutonium(IV) was possible to be oxidized to Pu(VI) by Mn oxide. Sterilized biogenic Mn oxide did not show the desorption behavior of Th(IV), indicating that living cells would release organic ligands strongly complexed with Th(IV).

Oral presentation

Time evolution calculation of muon catalyzed fusion by the Runge-Kutta method

Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

no journal, , 

A muon ($$mu$$) having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion ($$mu$$CF) between deuteron (d) and triton (t). In this work, we have solved simultaneous reaction rate equations by the 4th-order Runge-Kutta method for the jointed $$mu$$CF cycles in the two layers (H$$_{2}$$/D$$_{2}$$ and D$$_{2}$$/T$$_{2}$$). The T$$_{2}$$ concentration to maximize the intensities of fusion neutrons and muons emitted to the vacuum will be discussed.

Oral presentation

Detection of neutron detection of dd-$$mu$$CF experiment at J-PARC MLF

Natori, Hiroaki*; Doiuchi, Shogo*; Ishida, Katsuhiko*; Kino, Yasushi*; Miyake, Yasuhiro*; Miyashita, Konan*; Nakashima, Ryota*; Nagatani, Yukinori*; Nishimura, Shoichiro*; Oka, Toshitaka; et al.

no journal, , 

A muonic molecule which consists of muon and two hydrogen isotope nuclei (deuteron (d) or tritium (t)) decays immediately via nuclear fusion ($$mu$$CF) and the muon will be released as a recycling muon. We attempted to use these muons to develop the scanning muon microscope. In this work, we will report the detection of neutron which emits during the $$mu$$CF reaction.

30 (Records 1-20 displayed on this page)