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Hierarchical aggregation in a complex fluid; The Role of isomeric interconversion

Massey, D.*; Williams, C. D.*; Mu, J.*; Masters, A. J.*; 元川 竜平; 青柳 登; 上田 祐生; Antonio, M. R.*

Journal of Physical Chemistry B, 127(9), p.2052 - 2065, 2023/03

 被引用回数:0 パーセンタイル:0(Chemistry, Physical)

There is an ever-increasing body of evidence that metallic complexes, involving amphiphilic ligands, do not form normal solutions in organic solvents. Instead, they form complex fluids with intricate structures. For example, the metallic complexes may aggregate into clusters and these clusters themselves may aggregate into super-clusters. In order to gain a deeper insight into the mechanisms at play, we have used an improved force field to conduct extensive molecular dynamics simulations of a system composed of zirconium nitrate, water, nitric acid, tri-$$n$$-butyl phosphate and $$n$$-octane. The important new finding is that a dynamic equilibrium between the cis and trans isomers of the metal complex is likely to play a key role in the aggregation behavior. The isolated cis and trans isomers have similar energies but simulation indicates that the clusters consist predominantly of cis isomers. With increasing metal concentration, we hypothesize that more clustering occurs and the chemical equilibrium shifts towards the cis isomer. It is possible that such isomeric effects play a role in the liquid-liquid extraction of other species and the inclusion of such effects in flowsheet modelling may lead to a better description of the process.


On the adsorption and reactivity of element 114, flerovium

Yakushev, A.*; Lens, L.*; D$"u$llmann, Ch. E.*; Khuyagbaatar, J.*; J$"a$ger, E.*; Krier, J.*; Runke, J.*; Albers, H. M.*; 浅井 雅人; Block, M.*; et al.

Frontiers in Chemistry (Internet), 10, p.976635_1 - 976635_11, 2022/08

 被引用回数:8 パーセンタイル:86.69(Chemistry, Multidisciplinary)



Gaps in topological magnon spectra; Intrinsic versus extrinsic effects

Do, S.-H.*; Paddison, J. A. M.*; Sala, G.*; Williams, T. J.*; 金子 耕士; 桑原 慶太郎*; May, A. F.*; Yan, J.*; McGuire, M. A.*; Stone, M. B.*; et al.

Physical Review Letters, 106(6), p.L060408_1 - L060408_6, 2022/08

 被引用回数:6 パーセンタイル:84.62(Materials Science, Multidisciplinary)

For topological magnon spectra, determining and explaining the presence or absence of a gap at a magnon crossing point is a central issue. An inelastic neutron scattering study of a single crystals is a powerful experimental technique to investigate the spin dynamics and hence is widely employed to probe the magnetic excitation spectra of topological materials. However, when the neutron intensity rapidly disperses, such as near a crossing point for a Dirac magnon, the apparent spectrum is extremely sensitive to experimental conditions including sample mosaic, resolution, and integration range. Here we study a gapless Dirac magnon candidate CrCl$$_{3}$$ to show how the quantification of a gapless or gaped spectrum at the Dirac point is extremely sensitive to the integration range of data. Our work calls for a careful examination of reports of gaps in inelastic neutron scattering spectra to ensure that topological gaps are not misdiagnosed or overestimated due to experimental factors.


Improved measurement of the $$0_2^+rightarrow0_1^+$$ $$E$$0 transition strength for $$^{72}$$Se using the SPICE spectrometer

Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.

Physical Review C, 106(1), p.014312_1 - 014312_9, 2022/07

 被引用回数:2 パーセンタイル:66.35(Physics, Nuclear)

The selenium isotopes lie at the heart of a tumultuous region of the nuclear chart where shape coexistence effects grapple with neutron-proton pairing correlations, triaxiality, and the impending proton dripline. In this work a study of $$^{72}$$Se by internal conversion electron and $$gamma$$-ray spectroscopy was undertaken with the SPICE and TIGRESS arrays. New measurements of the branching ratio and lifetime of the $$0_2^+$$ state were performed yielding a determination of $$rho^2(E0; 0_2^+{rightarrow}0_1^+)=29(3)$$ milliunits. Two state mixing calculations were performed that highlighted the importance of interpretation of such $$E0$$ strength values in the context of shape-coexistence.


State-of-the-art of WPS in RPV PTS analysis

Zarazovski, M.*; Pistra, V.*; Lauerova, D.*; Obermeier, F.*; Mora, D.*; Dubyk, Y.*; Bolinder, T.*; Cueto-Felgueroso, C.*; Szavai, S.*; Dudra, J.*; et al.

Proceedings of ASME 2022 Pressure Vessels and Piping Conference (PVP 2022) (Internet), 11 Pages, 2022/07

The APAL (Advanced Pressurized Thermal Shock (PTS) Analysis for Long-Term Operation (LTO)) project was launched in October 2020 for four years with funding from the European Union's HORIZON 2020 program. Within APAL, an extensive literature review was performed and experience with defining the state-of-the-art of the Warm Pre-Stress (WPS) effect, which has an impact on the reactor pressure vessel (RPV) brittle fracture margin in both deterministic and probabilistic terms, was collected. To gather the worldwide experience of the WPS approaches and models, a comprehensive questionnaire was developed followed by each APAL partner response. It mainly focused on the following aspects: collection of existing WPS approaches and models implemented in standards and rules for RPV brittle fracture assessment; identification of the WPS issues; collection and analysis of the existing experimental data. This work describes worldwide experience and best practice of the WPS and its application for the RPV integrity assessment. The paper's conclusions are also focused on the recommendations for dealing with WPS issues.


A Telescoping view of solute architectures in a complex fluid system

元川 竜平; 小林 徹; 遠藤 仁; Mu, J.*; Williams, C. D.*; Masters, A. J.*; Antonio, M. R.*; Heller, W. T.*; 長尾 道弘*

ACS Central Science, 5(1), p.85 - 96, 2019/01

 被引用回数:43 パーセンタイル:87.17(Chemistry, Multidisciplinary)

We present a hierarchical aggregate model of an organic phase containing a coordination species that acts as a fundamental building unit of higher-order structures formed in the organic phase. We aimed to elucidate the fundamental aspects of the microscopic structure and phase separation occurring in ionic separation and recovery systems during solvent extraction. The coordination species aggregate through a hydrogen-bonding network formed by interaction between the hydrophilic part of the coordination species with extracted water and acid molecules. This reduces the hydrophilic surface area, resulting in subsequent formation of small primal clusters of 2 to 3 nm in diameter. The primal clusters further aggregate due to van der Waals interaction to form large aggregates of $$<$$ 10 nm in diameter. The size of the primal cluster does not depend on the concentration of the coordination species, whereas the size of the large aggregate increases as the aggregation number of the primal clusters increases. We conclude that hybrid interaction is a key driving force in the formation and growth of the hierarchical aggregate and the induction of phase separation of the organic phase.


The Application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Rameb$"a$ck, H.*; Nelwamondo, A. N.*; Kotze, D.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.425 - 434, 2018/02

 被引用回数:12 パーセンタイル:79.55(Chemistry, Analytical)



Comparative molecular dynamics study on tri-$$n$$-butyl phosphate in organic and aqueous environments and its relevance to nuclear extraction processes

Mu, J.*; 元川 竜平; Williams, C. D.*; 阿久津 和宏*; 西辻 祥太郎*; Masters, A. J.*

Journal of Physical Chemistry B, 120(23), p.5183 - 5193, 2016/06

 被引用回数:27 パーセンタイル:61.97(Chemistry, Physical)

A refined model for tri-$$n$$-butyl phosphate (TBP), which uses a new set of partial charges generated from our ab initio density functional theory calculations, has been proposed in this study. Molecular dynamics simulations are conducted to determine the thermodynamic properties, transport properties, and the microscopic structures of liquid TBP, TBP/water mixtures, and TBP/$$n$$-alkane mixtures. These results are compared with those obtained from four other TBP models, previously described in the literature. We conclude that our refined TBP model appears to be the only TBP model from this set that, with reasonable accuracy, can simultaneously predict the properties of TBP in bulk TBP, in organic diluents, and in aqueous solution. This new TBP model is thus appropriate for the simulation of liquid-liquid extraction systems in the nuclear extraction process, where one needs to simultaneously model TBP in both aqueous and organic phases. It is also promising for the investigation of the microscopic structure of the organic phase in these processes and for the characterization of third-phase formation, where TBP again interacts simultaneously with both polar and nonpolar molecules. Because the proposed TBP model uses OPLS-2005 Lennard-Jones parameters, it may be used with confidence to model mixtures of TBP with other species whose parameters are given by the OPLS-2005 force field.


Identification of deformed intruder states in semi-magic $$^{70}$$Ni

Chiara, C. J.*; Weisshaar, D.*; Janssens, R. V. F.*; 角田 佑介*; 大塚 孝治*; Harker, J. L.*; Walters, W. B.*; Recchia, F.*; Albers, M.*; Alcorta, M.*; et al.

Physical Review C, 91(4), p.044309_1 - 044309_10, 2015/04

 被引用回数:36 パーセンタイル:91.42(Physics, Nuclear)

アルゴンヌ国立研究所にて中性子過剰核$$^{70}$$Niを$$^{70}$$Znの多核子移行反応によって生成し、$$gamma$$線検出器GRETINAを用いて$$gamma$$線分光を行った。その結果、$$2^+_2$$, $$4^+_2$$準位を初めて観測した。これらの準位は小さな模型空間を採用した殻模型計算では再現されないため、陽子の$$f_{7/2}$$軌道からの励起を伴った大きな変形状態であると考えられる。本論文の理論グループが2014年に発表した大規模殻模型計算によって$$^{70}$$Niの励起状態を解析した結果、これらの状態は大きなプロレート変形を持つ状態とよく対応することがわかった。この結果は、中性子過剰ニッケル同位体における変形共存が$$^{68}$$Ni以外にも存在することを実証するとともに、中性子過剰核における大規模殻模型計算の予言能力を確かめるものである。


Li(Zn,Mn)As as a new generation ferromagnet based on a I-II-V semiconductor

Deng, Z.*; Jin, C. Q.*; Liu, Q. Q.*; Wang, X. C.*; Zhu, J. L.*; Feng, S. M.*; Chen, L. C.*; Yu, R. C.*; Arguello, C.*; 後神 達郎*; et al.

Nature Communications (Internet), 2, p.1425_1 - 1425_5, 2011/08

 被引用回数:150 パーセンタイル:93.66(Multidisciplinary Sciences)



Study of $$^{70,72}$$Se nuclear shapes with SPICE and TIGRESS

Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.

no journal, , 

The phenomenon of shape coexistence is prevalent in the Z$$sim$$34 region, with isotopes of neutron-deficient even Ge, Se and Kr each exhibiting the characteristic low-lying coexisting 0+ bands which display quadrupole deformation different to that of the ground states. In the selenium isotopes, $$^{72-78}$$Se seem to show a prolate ground structure with shape coexisting oblate excitation, while in $$^{68}$$Se the oblate structure appears to have become the ground state. The exact nature of the low-lying structure $$^{70}$$Se and any shape coexistence remains uncertain. Combining the Spectrometer for Internal Conversion Electrons (SPICE) with the TIGRESS HPGe Array, a full electron and gamma-ray experimental study of $$^{70}$$Se, $$^{72}$$Se was undertaken at the TRIUMF ISAC-II facility to unveil the low-lying structure of these nuclei. Details of the device and experiment will be presented, alongside the experimental results and possible structural interpretations for both isotopes.

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