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Journal Articles

Bench-scale injection of magnesium hydroxide encapsulated iron nanoparticles (nFe$$^{0}$$@Mg(OH)$$_{2}$$) into porous media for Cr(VI) removal from groundwater

Maamoun, I.; Falyouna, O.*; Eljamal, R.*; Idham, M. F.*; Tanaka, Kazuya; Eljamal, O.*

Chemical Engineering Journal, 451, Part3, p.138718_1 - 138718_22, 2023/01

 Times Cited Count:4 Percentile:95.16(Engineering, Environmental)

Journal Articles

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01

 Times Cited Count:0

Au(001) surfaces exhibit a complex reconstructed structure [Hex-Au(001)] comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene-Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a Hex-Au(001) surface. The crossing point of the original and replica graphene $$pi$$ bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene $$pi$$ and Au $$6sp$$ bands, indicating that the bandgap is generated using hybridization of the graphene $$pi$$ and Au $$6sp$$ bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene $$pi$$ and Au $$6sp$$ would result in spin injection into graphene.

Journal Articles

Benchmark analysis of FFTF Loss of Flow Without Scram Test No.13 using fast reactor plant dynamics analysis code Super-COPD

Hamase, Erina; Ohgama, Kazuya; Kawamura, Takumi*; Doda, Norihiro; Yamano, Hidemasa; Tanaka, Masaaki

Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 9 Pages, 2022/10

To improve the prediction accuracy of the plant dynamics analysis code named Super-COPD, JAEA has joined the IAEA benchmark for the FFTF Loss of Flow Without Scram Test No.13. In the first blind phase, there was the challenge to perform outlet temperatures of fuel assemblies more accurately. Hence, the renewed analysis was performed with the whole core multi-channel model in which each assembly was modelled to simulate the radial heat transfer among assemblies and the flow redistribution induced by the buoyancy in the NC conditions. Then, to validate the coupled transient analysis between the whole core multi-channel model and the one-point kinetics model, the analysis considering major reactivity feedbacks such as GEM, assembly bowing was performed. As a result, the second peak of outlet temperatures was reproduced successfully, and it was observed that the plant dynamics analysis could follow the measured data.

Journal Articles

Extended X-ray absorption fine structure spectroscopy measurements and ${it ab initio}$ molecular dynamics simulations reveal the hydration structure of the radium(II) ion

Yamaguchi, Akiko; Nagata, Kojiro*; Kobayashi, Keita; Tanaka, Kazuya; Kobayashi, Toru; Tanida, Hajime; Shimojo, Kojiro; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

iScience (Internet), 25(8), p.104763_1 - 104763_12, 2022/08

 Times Cited Count:1 Percentile:50.92(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Rapid and efficient chromium (VI) removal from aqueous solutions using nickel hydroxide nanoplates (nNiHs)

Maamoun, I.; Bensaida, K.*; Eljamal, R.*; Falyouna, O.*; Tanaka, Kazuya; Tosco, T.*; Sugihara, Yuji*; Eljamal, O.*

Journal of Molecular Liquids, 358, p.119216_1 - 119216_13, 2022/07

 Times Cited Count:7 Percentile:97.15(Chemistry, Physical)

Journal Articles

Multi-functional magnesium hydroxide coating for iron nanoparticles towards prolonged reactivity in Cr(VI) removal from aqueous solutions

Maamoun, I.; Falyouna, O.*; Eljamal, R.*; Bensaida, K.*; Tanaka, Kazuya; Tosco, T.*; Sugihara, Yuji*; Eljamal, O.*

Journal of Environmental Chemical Engineering, 10(3), p.107431_1 - 107431_17, 2022/06

 Times Cited Count:11 Percentile:96.51(Engineering, Environmental)

Journal Articles

Microbial influences on manganese deposit formation at Yunotaki Fall, Japan

Shiraishi, Fumito*; Chihara, Ryoji*; Tanimoto, Risa*; Tanaka, Kazuya; Takahashi, Yoshio*

Island Arc, 31(1), p.e12448_1 - e12448_9, 2022/05

 Times Cited Count:0 Percentile:0(Geosciences, Multidisciplinary)

At Yunotaki Fall in north Japan, manganese-oxidizing bacteria were previously assumed to have oxidized manganese to precipitate birnessite, which relied on oxygen released from algae. However, it remained unclear whether larger-scale manganese oxide precipitation was actually occurring under light conditions. This study evaluated the contribution of indirect oxidation using microelectrodes to analyze local water chemistry, in addition to bulk water chemistry and DNA analyses. The results of this study demonstrate that low bulk pH values in the hot spring water hindered indirect oxidation despite the occurrence of active oxygenic photosynthesis and that direct oxidation by manganese-oxidizing bacteria is considered to dominate in the investigated sample.

Journal Articles

Chemical species of iodine during sorption by activated carbon; Effects of original chemical species and fulvic acids

Kato, Tomoaki; Kozai, Naofumi; Tanaka, Kazuya; Kaplan, D. I.*; Utsunomiya, Satoshi*; Onuki, Toshihiko

Journal of Nuclear Science and Technology, 59(5), p.580 - 589, 2022/05

 Times Cited Count:1 Percentile:30.57(Nuclear Science & Technology)

This study reports the effect of fulvic acids, which is a natural organic substance generally contained in groundwater, on the oxidation states of radioactive iodine anions (iodide and iodate). Iodide and iodate are contained in the contaminated water of the Fukushima Daiichi Nuclear Power Plant and supposed to be removed by activated carbon (AC) via adsorption. When fulvic acids does not exist in the experimental system, the adsorption of iodide on AC was less than that of iodate and their oxidation states after the adsorption were not changed. When fulvic acids existed, a fraction of the adsorbed iodate was reduced to iodide. This result indicates that the reduction of the adsorbed iodate progresses during the storage of the spent AC.

Journal Articles

Effect of particle size on the colonization of biofilms and the potential of biofilm-covered microplastics as metal carriers

Wu, C.*; Tanaka, Kazuya; Tani, Yukinori*; Bi, X.*; Liu, J.*; Yu, Q.*

Science of the Total Environment, 821, p.153265_1 - 153265_9, 2022/05

 Times Cited Count:7 Percentile:96.64(Environmental Sciences)

Microplastics (MPs) with different particle sizes were co-cultured with a model freshwater fungus, ${it Acremonium strictum}$ strain KR21-2, to form biofilms on their surface. We also determined the changes in surface physicochemical properties of the biofilm-covered MPs (BMPs) and the heavy metal adsorption capacity of the original MPs and BMPs. The results revealed that the biofilms improve the adsorption of heavy metals on MPs, and the particle size of MPs plays a crucial role in biofilm colonization and adsorption of heavy metals by BMPs.

Journal Articles

${it Operando}$ structure observation of pyroelectric ceramics during power generation cycle

Kawasaki, Takuro; Fukuda, Tatsuo; Yamanaka, Satoru*; Sakamoto, Tomokazu*; Murayama, Ichiro*; Kato, Takanori*; Baba, Masaaki*; Hashimoto, Hideki*; Harjo, S.; Aizawa, Kazuya; et al.

Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04

 Times Cited Count:0 Percentile:0(Physics, Applied)

Journal Articles

Insights into boron removal from water using Mg-Al-LDH; Reaction parameters optimization & 3D-RSM modeling

Eljamal, O.*; Maamoun, I.; Alkhudhayri, S.*; Eljamal, R.*; Falyouna, O.*; Tanaka, Kazuya; Kozai, Naofumi; Sugihara, Yuji*

Journal of Water Process Engineering (Internet), 46, p.102608_1 - 102608_13, 2022/04

 Times Cited Count:4 Percentile:88.06(Engineering, Environmental)

Journal Articles

Investigation of hydration and adsorption structures on clay minerals of radium by EXAFS

Yamaguchi, Akiko; Nagata, Kojiro*; Tanaka, Kazuya; Kobayashi, Keita; Kobayashi, Toru; Shimojo, Kojiro; Tanida, Hajime; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

Hosha Kagaku, (45), p.28 - 30, 2022/03

no abstracts in English

Journal Articles

Synthesis of hybrid magnesium hydroxide/magnesium oxide nanorods [Mg(OH)$$_{2}$$/MgO] for prompt and efficient adsorption of ciprofloxacin from aqueous solutions

Falyouna, O.*; Bensaida, K.*; Maamoun, I.; Ashik, U. P. M.*; Tahara, Atsushi*; Tanaka, Kazuya; Aoyagi, Noboru; Sugihara, Yuji*; Eljamal, O.*

Journal of Cleaner Production, 342, p.130949_1 - 130949_15, 2022/03

 Times Cited Count:7 Percentile:95.42(Green & Sustainable Science & Technology)

Journal Articles

Simultaneous sequestration of Co$$^{2+}$$ and Mn$$^{2+}$$ by fungal manganese oxide through asbolane formation

Aoshima, Miku*; Tani, Yukinori*; Fujita, Rina*; Tanaka, Kazuya; Miyata, Naoyuki*; Umezawa, Kazuhiro*

Minerals (Internet), 12(3), p.358_1 - 358_16, 2022/03

 Times Cited Count:3 Percentile:84.18(Geochemistry & Geophysics)

In this study, we conducted sequestration experiments of Co$$^{2+}$$ by ${it Acremonium strictum}$ KR21-2 in a Mn$$^{2+}$$/Co$$^{2+}$$ binary solution at pH7. The sequestration of Co$$^{2+}$$ by newly formed BMOs readily progressed in parallel with the exogenous Mn$$^{2+}$$, with higher efficiency than that in single Co$$^{2+}$$ solutions. This is attributed to a synergetic effect on Co$$^{2+}$$ sequestration through the formation of asbolane in Mn$$^{2+}$$/Co$$^{2+}$$ binary systems.

Journal Articles

Sorption of Pu(IV) on biogenic Mn oxide and complexation of Pu(IV) with organic ligands secreted by fungal cells

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

Journal of Radioanalytical and Nuclear Chemistry, 331(2), p.1109 - 1114, 2022/02

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

We investigated the sorption of Pu(IV) on biogenic Mn oxide produced by Mn(II)-oxidizing fungus. The sorption of Pu(IV) on biogenic Mn oxide was similar to that of U(VI) and different from that of Th(IV), possibly due to oxidation of Pu(IV) to Pu(VI). When Pu(IV) was sorbed on hyphae only, it was desorbed into the solution phase over time. Pu(IV) could be solubilized by complexation with organic ligands secreted by fungal cells. In particular, Pu(IV) desorption was observed under circumneutral pH conditions.

Journal Articles

Preface to the special issue on the Fukushima Daiichi Nuclear Power Plant accident and geochemistry; 10 years after the Fukushima accident

Tanaka, Kazuya; Yamasaki, Shinya*

Chikyu Kagaku, 55(4), p.93 - 95, 2021/12

Ten years have passed since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. In this special issue, we compiled review papers on the environmental behavior of the FDNPP-derived radionuclides from various research fields. This special issue shows that various research fields contributed to better understandings on the environmental behavior of the FDNPP-derived radionuclides.

Journal Articles

High spatial resolution neutron transmission imaging using a superconducting two-dimensional detector

Shishido, Hiroaki*; Nishimura, Kazuma*; Vu, TheDang*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; et al.

IEEE Transactions on Applied Superconductivity, 31(9), p.2400505_1 - 2400505_5, 2021/12

In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl$$_{3}$$ were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the $$_{155}$$Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 $$mu$$m $$times$$ 12 $$mu$$m. Gd selective imaging was performed using the resonance dip of $$_{155}$$Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.

Journal Articles

Fe, Mn and $$^{238}$$U accumulations in ${it Phragmites australis}$ naturally growing at the mill tailings pond; Iron plaque formation possibly related to root-endophytic bacteria producing siderophores

Nakamoto, Yukihiro*; Doyama, Kohei*; Haruma, Toshikatsu*; Lu, X.*; Tanaka, Kazuya; Kozai, Naofumi; Fukuyama, Kenjin; Fukushima, Shigeru; Ohara, Yoshiyuki; Yamaji, Keiko*

Minerals (Internet), 11(12), p.1337_1 - 1337_17, 2021/12

 Times Cited Count:0 Percentile:0.02(Geochemistry & Geophysics)

Mine drainage is a vital water problem in the mining industry worldwide because of the heavy metal elements and low pH. Rhizofiltration using wetland plants is an appropriate method to remove heavy metals from the water via accumulation in the rhizosphere. ${it Phragmites australis}$ is one of the candidate plants for this method because of metal accumulation, forming iron plaque around the roots. At the study site, which was the mill tailings pond in the Ningyo-toge uranium mine, ${it P. australis}$ has been naturally growing since 1998. The results showed that ${it P. australis}$ accumulated Fe, Mn, and $$^{238}$$U in the nodal roots without/with iron plaque compared with other plant tissues. Among the 837 bacterial colonies isolated from nodal roots, 88.6% showed siderophore production activities. Considering iron plaque formation around ${it P. australis}$ roots, we hypothesized that microbial siderophores might influence iron plaque formation because bacterial siderophores have catechol-like functional groups. The complex of catechol or other phenolics with Fe was precipitated due to the networks between Fe and phenolic derivatives. The experiment using bacterial products of root endophytes, such as ${it Pseudomonas}$ spp. and ${it Rhizobium}$ spp., showed precipitation with Fe ions, and we confirmed that several ${it Ps.}$ spp. and ${it R.}$ spp. produced unidentified phenolic compounds. In conclusion, root-endophytic bacteria such as ${it Pseudomonas}$ spp. and ${it R.}$ spp., isolated from metal-accumulating roots of ${it P. australis}$, might influence iron plaque formation as the metal accumulation site. Iron plaque formation is related to tolerance in ${it P. australis}$, and ${it Ps.}$ spp. and ${it R.}$ spp. might indirectly contribute to tolerance.

Journal Articles

Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11

 Times Cited Count:3 Percentile:40.73(Environmental Sciences)

This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.

Journal Articles

Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Vu, TheDang; Shishido, Hiroaki*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.

Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

232 (Records 1-20 displayed on this page)