Magnetite stoichiometry (Fe(II)/Fe(III)) controls on trivalent chromium surface speciation

Scaria, J.*; Pdrot, M.*; Fablet, L.*; Yomogida, Takumi; Nguyen, T. T.*; Sivry, Y.*; Catrouillet, C.*; Pradas del Real, A. E.*; Choueikani, F.*; Vantelon, D.*; et al.

Environmental Science & Technology, 59(11), p.5747 - 5755, 2025/03

https://doi.org/10.1021/acs.est.4c12899

Understanding and predicting the interaction mechanisms between chromium and magnetite is of particular interest to elucidate the biogeochemical behavior of Cr in the environment and to develop optimal soil remediation and water treatment strategies. However, while the elimination of the most toxic form of (Cr(VI)) by its reduction to Cr(III) has widely been documented, elucidating the exact mechanism involved in Cr(III) sorption to magnetite has attracted less attention. This study examined the interaction of Cr(III) solution with 10 nm-sized magnetites, whose stoichiometries were carefully defined and preserved in anaerobic conditions. This study reveals the joint effects of pH and magnetite stoichiometry on Cr(III) sorption mechanism, and that Cr(III)-(hydr)oxide precipitation is not necessarily the driving process of Cr(III) elimination from solutions. These results will help predict the fate and transport of chromium, as well as developing magnetite-based chromium remediation processes.

Mechanical properties of base metal and heat-affected zone in friction-stir-welded AA6061-T6 at ultra-low temperature of 20 K

Nguyen, T.-D.*; Singh, C.*; Kim, Y. S.*; Han, J. H. *; Lee, D.-H.*; Lee, K.*; Harjo, S.; Lee, S. Y.*

Journal of Materials Research and Technology, 31, p.1547 - 1556, 2024/07

https://doi.org/10.1016/j.jmrt.2024.06.165

Extraction of Mo hot atoms made by a neutron capture method from -MoO to water

Quach, N. M.*; Ngo, M. C.*; Yang, Y.*; Nguyen, T. B.*; Nguyen, V. T.*; Fujita, Yoshitaka; Do, T. M. D.*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Suematsu, Hisayuki*

Journal of Radioanalytical and Nuclear Chemistry, 332(10), p.4057 - 4064, 2023/10

https://doi.org/10.1007/s10967-023-09125-7

Technetium-99m (Tc) is the most widely used medical radioisotope in the world and is produced from molybdenum-99 (Mo). Production of Mo via the neutron capture method draws attention as an alternative to fission-derived Mo due to non-proliferation issues, but the specific radioactivity of Mo is extremely low. In this work, a porous -MoO wire was prepared as an irradiation target in order to improve the specific activity by extracting Mo. Porous -MoO wire is synthesized from Mo metal wire by a two-step heating procedure. The hot atom effect of Mo was confirmed by activity and isotope measurements of the porous -MoO wire after neutron irradiation and the water used for extraction. In term of the extraction effectiveness, the effectiveness of Mo extraction in the porous -MoO wire was comparable to that of commercial -MoO powder.

Selective recovery of thorium and uranium from leach solutions of rare earth concentrates in continuous solvent extraction mode with primary amine N1923

Nguyen, T. H.*; Le Ba, T.*; Tran, C. T.*; Nguyen, T. T.*; Doan, T. T. T.*; Do, V. K.; Watanabe, Masayuki; Pham, Q. M.*; Hoang, S. T.*; Nguyen, D. V.*; et al.

Hydrometallurgy, 213, p.105933_1 - 105933_11, 2022/08

https://doi.org/10.1016/j.hydromet.2022.105933

A continuous counter-current extraction for the selective recovery of thorium (Th) and uranium (U) from the Yen Phu (Vietnam) rare earth concentrate leach solutions was systematically studied. The primary amine N1923 was used as an extractant which was prepared in the isoparaffin IP-2028 diluent. Thorium and uranium were selectively recovered in a hydrometallurgical circuit established by continuous mixer-settler extraction, scrubbing, and back-extraction at the laboratory scale. The desired purity of Th and U can be achieved by managing the volume ratio of organic to aqueous phase (O/A ratio) in the corresponding steps. Highly pure Th and U were recovered from the pregnant back-extraction liquor and the raffinate, respectively, which have satisfactory properties for further processing of the subsequent nuclear materials.

Numerical study on longitudinal distance effect on failure stress of non-aligned twin cracked pipe

Nguyen, T.-L.*; Lee, M.-W.*; Hasegawa, Kunio; Kim, Y.-J.*

Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 7 Pages, 2018/07

The effect of longitudinal distance H between non-aligned twin cracks is investigated using finite element damage analysis. It is shown that the failure bending stresses are raised by increasing longitudinal distance H for deep short cracks. On the contrary, shallow long cracks are unaffected by the distance H.

Identified charged hadron production in collisions at = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

https://doi.org/10.1103/PhysRevC.83.064903

Transverse momentum distributions and yields for , and in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as and scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in and Au+Au collisions at = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

https://doi.org/10.1103/PhysRevC.83.044912

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.

Emulsion grafting of glycidyl methacrylate onto polyethylene fiber

Seko, Noriaki; Nguyen, T. Y. N.*; Tamada, Masao

Radiation Physics and Chemistry, 79(1), p.22 - 26, 2010/01

https://doi.org/10.1016/j.radphyschem.2009.08.014

Graft polymerization of glycidyl methacrylate (GMA) onto polyethylene fiber was carried out in emulsion solution obtained by dissolving GMA in water with sodium n-dodecyl sulfate (SDS) as a surfactant. GMA micelles diameter was 415 nm at 5% GMA with 4% SDS and increased up to 1840 nm at 10% GMA with 12% SDS. Degree of grafting (Dg) which was estimated by the weight gain after grafting increased with the increment of GMA concentration in the range of 2-8% and slightly reduced at 10% GMA. The increment in SDS concentration from 4% to 16% at 5% GMA reduced Dg from 120% to 18%. In emulsion graft polymerization, Dg was affected by covered area by GMA/SDS micelles on the fiber.

Use of positron-emitting tracer imaging system for measuring the effect of salinity on temporal and spatial distribution of C tracer and coupling between source and sink organs

Suwa, Ryuichi*; Fujimaki, Shu; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; Sakamoto, Koichi*; Nguyen, N. T.*; Saneoka, Hirofumi*; Mohapatra, P. K.*; Moghaieb, R. E.*; et al.

Plant Science, 175(3), p.210 - 216, 2008/09

https://doi.org/10.1016/j.plantsci.2008.03.022

Model calibration of small and large-scale laboratory THM experiments of the MX-80 bentonite

Chijimatsu, Masakazu*; Brgesson, L.*; Fujita, Tomoo; Hernelind, J.*; Jussila, P.*; Nguyen, T. S.*; Rutqvist, J.*; Jing, L.*

Proceedings of 2nd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2006), p.254 - 260, 2006/05

In Task A of DECOVALEX-THMC, five research teams study the influence of THM coupling on the safety of the near-field of a typical geological repository for high-level radioactive waste. In order to refine the analyses, the teams calibrated their models with laboratory experiments, including: swelling pressure tests, water uptake tests, thermally gradient tests, and the CEA mock-up THM experiment. This paper describes the mathematical models used by the teams, and compares the results of their calibration with the experimental data.