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Journal Articles

Prediction of stability constants for novel chelates design in minor actinides partitioning over lanthanides using density functional theory calculation

Kaneko, Masashi; Sasaki, Yuji; Wada, Eriko*; Nakase, Masahiko*; Takeshita, Kenji*

Chemistry Letters, 50(10), p.1765 - 1769, 2021/10

 Times Cited Count:0

Density functional theory calculation is applied to predict the stability constants for Eu$$^{3+}$$ and Am$$^{3+}$$ complexes in aqueous solution for molecular modelling of novel separation agents for minor actinides over lanthanides. Logarithm of experimental stability constants correlates with calculated complex formation enthalpies with high reproducibility (R$$^{2}$$ $$>$$ 0.98). Prediction of stability constants of novel chelates is demonstrated and indicates a potential availability of the derivatives of diethylenetriaminepentaacetic acid type chelate in acidic condition and enhancement of Am$$^{3+}$$ selectivity over Eu$$^{3+}$$.

Journal Articles

Highly-sensitive analysis of fluorescence XANES at Europium (Eu) L$$_{rm III}$$-edge for the determination of oxidation state for trace amount of Eu in natural samples by bragg-type crystal analyzer system

Konagaya, Rimi*; Kawamura, Naomi*; Yamaguchi, Akiko; Takahashi, Yoshio*

Chemistry Letters, 50(8), p.1570 - 1572, 2021/08

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

no abstracts in English

Journal Articles

Electrochemical studies of uranium (IV) in an ionic liquid-DMF mixture to build a redox flow battery using uranium as an electrode active material

Ouchi, Kazuki; Komatsu, Atsushi; Takao, Koichiro*; Kitatsuji, Yoshihiro; Watanabe, Masayuki

Chemistry Letters, 50(6), p.1169 - 1172, 2021/06

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

The electrochemical behavior of uranium (IV) tetrachloride in ionic liquid-DMF mixture was studied for first time in order to build a redox flow battery (RFB) using U as an electrode active material. We found a quasi-reversible U$$^{III}$$/U$$^{IV}$$ couple that could be applied to the anode reaction of the RFB.

Journal Articles

Freezable and unfreezable hydration water; Distinct contributions to protein dynamics revealed by neutron scattering

Yamamoto, Naoki*; Kofu, Maiko; Nakajima, Kenji; Nakagawa, Hiroshi; Shibayama, Naoya*

Journal of Physical Chemistry Letters (Internet), 12(8), p.2172 - 2176, 2021/03

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

Hydration water plays a crucial role for activating the protein dynamics required for functional expression. Yet, the details are not understood about how hydration water couples with protein dynamics. A temperature hysteresis of the ice formation of hydration water is a key phenomenon to understand which type of hydration water, unfreezable or freezable hydration water, is crucial for the activation of protein dynamics. Using neutron scattering, we observed a temperature-hysteresis phenomenon in the diffraction peaks of the ice of freezable hydration water, whereas protein dynamics did not show any temperature hysteresis. These results show that the protein dynamics is not coupled with freezable hydration water dynamics, and unfreezable hydration water is essential for the activation of protein dynamics.

Journal Articles

Neutron spin-echo studies of the structural relaxation of network liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak

Luo, P.*; Zhai, Y.*; Leao, J. B.*; Kofu, Maiko; Nakajima, Kenji; Faraone, A.*; Zhang, Y.*

Journal of Physical Chemistry Letters (Internet), 12(1), p.392 - 398, 2021/01

 Times Cited Count:1 Percentile:70.6(Chemistry, Physical)

Using neutron spin-echo spectroscopy, we studied the microscopic structural relaxation of a prototypical network ionic liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak. The results show that the relaxation at the primary peak is faster than the prepeak and that the activation energy is $$sim 33$$% higher. A stretched exponential relaxation is observed even at temperatures well-above the melting point $$T_{rm m}$$. Surprisingly, the stretching exponent shows a rapid increase upon cooling, especially at the primary peak, where it changes from a stretched exponential to a simple exponential on approaching the $$T_{rm m}$$. These results suggest that the appearance of glassy dynamics typical of the supercooled state even in the equilibrium liquid state of ZnCl$$_2$$ as well as the difference of activation energy at the two investigated length scales are related to the formation of a network structure on cooling.

Journal Articles

Gas barrier properties of chemical vapor-deposited graphene to oxygen imparted with sub-electronvolt kinetic energy

Ogawa, Shuichi*; Yamaguchi, Hisato*; Holby, E. F.*; Yamada, Takatoshi*; Yoshigoe, Akitaka; Takakuwa, Yuji*

Journal of Physical Chemistry Letters (Internet), 11(21), p.9159 - 9164, 2020/11

 Times Cited Count:2 Percentile:42.52(Chemistry, Physical)

Atomically thin layers of graphene have been proposed to protect surfaces through the direct blocking of corrosion reactants such as oxygen with low added weight. The long term efficacy of such an approach, however, is unclear due to the long-term desired protection of decades and the presence of defects in as-synthesized materials. Here, we demonstrate catalytic permeation of oxygen molecules through previously-described impermeable graphene by imparting sub-eV kinetic energy to molecules. These molecules represent a small fraction of a thermal distribution thus this exposure serves as an accelerated stress test for understanding decades-long exposures. The permeation rate of the energized molecules increased 2 orders of magnitude compared to their non-energized counterpart. Graphene maintained its relative impermeability to non-energized oxygen molecules even after the permeation of energized molecules indicating that the process is non-destructive and a fundamental property of the exposed material.

Journal Articles

Nanoscale relaxation in "Water-in-Salt" and "Water-in-Bisalt" electrolytes

Gonzal$'e$z, M. A.*; Borodin, O.*; Kofu, Maiko; Shibata, Kaoru; Yamada, Takeshi*; Yamamuro, Osamu*; Xu, K.*; Price, D. L.*; Saboungi, M.-L.*

Journal of Physical Chemistry Letters (Internet), 11(17), p.7279 - 7284, 2020/09

 Times Cited Count:6 Percentile:81.96(Chemistry, Physical)

Journal Articles

Local structure of rare earth elements (REE) in marine ferromanganese oxides by extended X-ray absorption fine structure and its comparison with REE in ion-adsorption type deposits

Nagasawa, Makoto*; Qin, H.-B.*; Yamaguchi, Akiko; Takahashi, Yoshio*

Chemistry Letters, 49(8), p.909 - 911, 2020/08

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

Journal Articles

Nanostructural characterization of oleyl acid phosphate in poly-$$alpha$$-olefin using small-angle X-ray scattering

Oba, Yojiro; Motokawa, Ryuhei; Hino, Masahiro*; Adachi, Nozomu*; Todaka, Yoshikazu*; Inoue, Rintaro*; Sugiyama, Masaaki*

Chemistry Letters, 49(7), p.823 - 825, 2020/07

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

Journal Articles

Bromine-isotope selective ionization using field-free alignment of IBr isotopologues with a switched nanosecond laser pulse

Akagi, Hiroshi*; Kumada, Takayuki; Otobe, Tomohito*; Itakura, Ryuji*; Hasegawa, Hirokazu*; Oshima, Yasuhiro*

Chemistry Letters, 49(4), p.416 - 418, 2020/04

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

Journal Articles

Segmental motions of proteins under non-native states evaluated using quasielastic neutron scattering

Fujiwara, Satoru*; Matsuo, Tatsuhito*; Sugimoto, Yasunobu*; Shibata, Kaoru

Journal of Physical Chemistry Letters (Internet), 10(23), p.7505 - 7509, 2019/12

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

Characterization of the dynamics of disordered polypeptide chains is required to elucidate the behavior of intrinsically disordered proteins and proteins under non-native states related to the folding process. Here we develop a method using quasielastic neutron scattering, combined with small-angle X-ray scattering and dynamic light scattering, to evaluate segmental motions of proteins as well as diffusion of the entire molecules and local side-chain motions. We apply this method to RNase A under the unfolded and molten-globule (MG) states. The diffusion coefficients arising from the segmental motions are evaluated and found to be different between the unfolded and MG states. The values obtained here are consistent with those obtained using the fluorescence-based techniques. These results demonstrate not only feasibility of this method but also usefulness to characterize the behavior of proteins under various disordered states.

Journal Articles

Finding free-energy landmarks of chemical reactions

Shiga, Motoyuki; Tuckerman, M. E.*

Journal of Physical Chemistry Letters (Internet), 9(21), p.6207 - 6214, 2018/11

 Times Cited Count:4 Percentile:30.21(Chemistry, Physical)

Predicting reaction pathways is one of the most important goals in theoretical and computational chemistry. In this paper, we propose a novel approach to search for free-energy landmarks, i.e., minima and the saddle points, of chemical reactions in an automated manner using a combination of steepest descent and gentlest ascent methods. As demonstrations, we present applications to the ring-opening reaction of benzocyclobutene and an SN2 reaction in aqueous solution.

Journal Articles

Rechargeable batteries based on stable redox reactions of disulfide included in a metal-organic framework as ligands

Shimizu, Takeshi*; Wang, H.*; Tanifuji, Naoki*; Matsumura, Daiju; Yoshimura, Masashi*; Nakanishi, Koji*; Ota, Toshiaki*; Yoshikawa, Hirofumi*

Chemistry Letters, 47(5), p.678 - 681, 2018/05

 Times Cited Count:3 Percentile:20.27(Chemistry, Multidisciplinary)

Journal Articles

Sorption behavior of Np(V) on microbe pure culture and consortia

Onuki, Toshihiko; Kozai, Naofumi; Sakamoto, Fuminori; Utsunomiya, Satoshi*; Kato, Kenji*

Chemistry Letters, 46(5), p.771 - 774, 2017/05

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

The sorption behavior of Np(V) by the microbe consortia and by a single pure culture of Fe reducing bacterium was studied at pH between 3 and 7 in resting cell conditions. The sorption of Np(V) by the Fe reducing bacterium obtained in the inert condition and by the consortia in aerated condition were higher than by the Fe reducing bacterium in aerobic condition at pH below 5, strongly suggesting presence of other mechanism than the adsorption on microbial cell surface, i.e. reduction to Np(IV).

Journal Articles

Efficient adsorption of Rh(III) from HNO$$_{3}$$ solution on ion-exchange resin bearing ${it N,N,N}$-trimethylglycine by adding N donor ligands and desorption using thiourea

Suzuki, Tomoya; Morita, Keisuke; Sasaki, Yuji

Chemistry Letters, 44(2), p.152 - 153, 2015/02

 Times Cited Count:2 Percentile:10.24(Chemistry, Multidisciplinary)

To recover Rh(III) from HNO$$_{3}$$ solution, adsorption experiments have been performed using an ion-exchange resin bearing an ${it N,N,N}$-trimethylglycine group (AMP03). AMP03 was found to exhibit relatively high adsorption ability for Rh(III) for [HNO$$_{3}$$]$$_{rm surp}$$ $$<$$ 0.02 M ([HNO$$_{3}$$]$$_{rm surp}$$ denotes HNO$$_{3}$$ concentration in the supernatant), and the ${it K$_{d}$}$ values increase significantly with the addition of triethylamine or tris(2-aminoethyl)amine to 0.12 M HNO$$_{3}$$ solutions. In contrast, the addition of thiourea leads to a decrease in the ${it K$_{d}$}$ values; i.e., a masking effect on Rh(III) was observed. These results show that AMP03 has a significant potential for effectively recovering Rh from HNO$$_{3}$$ solution.

Journal Articles

Complexing agents for oxonium anions of Mo and Re and their masking effects on extraction using N-donor extractants

Sasaki, Yuji; Suzuki, Tomoya; Morita, Keisuke; Tsubata, Yasuhiro

Chemistry Letters, 43(10), p.1538 - 1539, 2014/10

 Times Cited Count:4 Percentile:19.55(Chemistry, Multidisciplinary)

Several complexing agents including soft donor in their structures are examined for the masking effects of Mo and Re through solvent extraction. The available extractants are hexaoctyl-nitrilotriacetamide (NTAamide) and methyliminodioctylacetamide (MIDOA), whose extractants have high D(Mo, Re). It is clear that Mo and Re in HNO$$_{3}$$ dissolving N-donor ligands, ethylenediamine, diethylenetriamine, and 1,3-diaminopropane, can be suppressed for extraction into organic phase. The ligands including sulfur donor, e.g., thiourea, are also tested, however, less masking effect can be seen.

Journal Articles

Uranyl species in 1-Ethyl-3-methylimidazolium nitrate ([EMI][NO$$_{3}$$]) solution of [EMI]$$_{2}$$[UO$$_{2}$$(NO$$_{3}$$)$$_{4}$$]; First spectrophotometric evidence for existence of [UO$$_{2}$$(NO$$_{3}$$)$$_{4}$$]$$^{2-}$$

Sasaki, kotoe*; Suzuki, Tomoya*; Arai, Tsuyoshi*; Takao, Koichiro*; Suzuki, Shinichi; Yaita, Tsuyoshi; Ikeda, Yasuhisa*

Chemistry Letters, 43(5), p.670 - 672, 2014/05

 Times Cited Count:6 Percentile:26.82(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Adsorption behavior of lanthanide ions on nonbiological phospholipid membranes; A Model study using liposome

Yamasaki, Shinya; Shirai, Osamu*; Kano, Kenji*; Kozai, Naofumi; Sakamoto, Fuminori; Onuki, Toshihiko

Chemistry Letters, 42(8), p.819 - 821, 2013/08

 Times Cited Count:4 Percentile:18.93(Chemistry, Multidisciplinary)

The adsorption behavior of lanthanide ions (except for Pm) on liposomes composed of phosphatidylcholine and cholesterol was examined to understand the interaction between lanthanide ions and the phosphoryl moiety of phospholipids. The adsorption of lanthanide ions increased with an increase in pH under the weakly acidic conditions. Selective adsorption with the local maximum at the Er$$^{3+}$$ ion and local minimum at the Er$$^{3+}$$ ion was observed, similar to the selective adsorption of the bacterial cell surface but different from that of orthophosphates. These results indicate that the adsorption of lanthanide on the phospholipid does not result from simple adsorption on orthophosphate functional groups but by the composition and molecular structure of the phospholipid. Our results strongly suggest that liposomes can be used as a simple biomembrane model without any biological activity for the study of adsorption of lanthanide ions.

Journal Articles

Redox behavior of uranium(VI) adsorbed onto a phosphate-modified indium tin oxide electrode

Suzuki, Yoshinori*; Nankawa, Takuya; Onuki, Toshihiko

Chemistry Letters, 42(8), p.888 - 890, 2013/08

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

no abstracts in English

Journal Articles

Novel soft-hard donor ligand, NTAamide, for mutual separation of trivalent actinides and lanthanides

Sasaki, Yuji; Tsubata, Yasuhiro; Kitatsuji, Yoshihiro; Morita, Yasuji

Chemistry Letters, 42(1), p.91 - 92, 2013/01

 Times Cited Count:28 Percentile:68.24(Chemistry, Multidisciplinary)

The new N-donor extractant, NTAamide, is synthesized and tested for extraction and separation of Am-Cm-Ln. It was found that the high separation factors for An-Ln can be seen at 0.1-0.2M HNO$$_{3}$$, which suggest the de-protonation to N donor is important to show the high SF between An and Ln. From the present work, the stable N-donor extractant having high SF of An-Ln from nitric acid to n-dodecane can be obtained. The highest separation factor, 6.5, of Am-Cm for the condition of 0.5M NTAamide (C8) in n-dodecane and 10 mM TEDGA in 0.2M HNO$$_{3}$$ as one of the highest SF values is found. NTAamide is the promising extractants for partitioning process of Am-Cm-Ln.

92 (Records 1-20 displayed on this page)