リュツォ・ホルム湾，プリンスオラフ海岸，及び，エンダビーランド地質調査隊報告2016-2017（JARE-58）

第58次日本南極地域観測隊（JARE-58）では，2016−2017の夏期期間にリュツォ・ホルム湾，プリンスオラフ海岸，及び，エンダビーランドにおいて地質調査をおこなった．調査隊のメンバーは，日本人地質研究者4名とアジア地域（タイ，インドネシア，モンゴル）の交換科学者3名で構成され，本吉隊長が一部期間の調査に加わった．第58次夏期観測では，「しらせ」搭載の2機の大型ヘリコプター（CH101）とともに観測隊チャーターの小型ヘリコプター（AS350）1機による野外調査の支援がなされた．本稿では，観測計画を実施するための，主に設営面での計画，準備，そして行動経過について報告する．The 58th Japanese Antarctic Research Expedition (JARE-58) conducted geological field surveys in the regions of Lützow-Holm Bay, Prince Olav Coast, and Enderby Land during the 2016−2017 austral summer season. The field party consisted of four Japanese geologists and three Asian geologists (Thai, Indonesian, Mongolian), and was joined periodically by JARE-58 expedition leader, Prof. Motoyoshi. Field parties were supported throughout the summer season by a smaller secondary helicopter (AS350) in addition to two main helicopters (CH101) stationed on the icebreaker Shirase. This report summarizes field preparations and the geological work undertaken, and highlights several key points for future planning and research

Local Electronic Structure Modulation of Interfacial Oxygen Vacancies Promotes the Oxygen Activation Capacity of Pt/Ce_1–<i>x</i>M_<i>x</i>O_2−δ

The asymmetric oxygen vacancies on the surface of doped oxides and at the interface between the metal and oxide are commonly regarded as the real active sites for the molecular oxygen activation reaction, owing to their unique electronic perturbation properties. However, the essential rules for modulating the local electronic structure of oxygen vacancies to promote the oxygen activation capacity are still ambiguous. In this work, a series of interfacial oxygen vacancy sites, Pt/Ce–Ov–M (Ov, oxygen vacancy, M = Y, La, Pr, and Nd), with different local coordination environments were constructed based on Pt/Ce0.95M0.05O2−δ materials. The experimental data and theoretical calculation results prove that the interfacial Pt/Ce–Ov–M site can capture electrons from Pt d-bands and M d- and f-bands, acting as an electron enrichment center. The elevated M d-band center upward to the Fermi level can significantly boost the electron transfer from d-bands to the unoccupied π2p* orbital of O2, achieving O2 activation through the π-electron feedback mechanism. Remarkably, Pt/Ce–Ov–Y sites in Pt/Ce0.95Y0.05O2−δ with the highest delocalized electron density exhibited the best O2 activation behaviors and catalytic activity in the aerobic oxidation of 5-hydroxymethylfurfural. This work reveals that the activation of O2 over metal-oxide catalysts is highly dependent on the interfacial electron transfer and d/f-orbital valence-electron modulation, providing more insights into the effect of oxygen vacancy-localized electronic perturbation on the oxygen activation performance

Fate and Phytotoxicity of CeO₂ Nanoparticles on Lettuce Cultured in the Potting Soil Environment

<div><p>Cerium oxide nanoparticles (CeO₂ NPs) have been shown to have significant interactions in plants. Previous study reported the specific-species phytotoxicity of CeO₂ NPs by lettuce (<i>Lactuca sativa</i>), but their physiological impacts and vivo biotransformation are not yet well understood, especially in relative realistic environment. Butterhead lettuce were germinated and grown in potting soil for 30 days cultivation with treatments of 0, 50, 100, 1000 mg CeO₂ NPs per kg soil. Results showed that lettuce in 100 mg·kg^-1 treated groups grew significantly faster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD), Peroxidase (POD), Malondialdehyde(MDA) activity was disrupted by 1000 mg·kg^-1 CeO₂ NPs treatment. In addition, the presence of Ce (III) in the roots of butterhead lettuce explained the reason of CeO₂ NPs phytotoxicity. These findings demonstrate CeO₂ NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.</p></div

XANES Ce LIII-edge spectra (5723 eV) in roots of butterhead lettuce treated with CeO₂ NPs.

<p>The dotted line indicates the feature a, b and c.</p

(A) Ce contents in roots (A) and leaves (B) of lettuce plants.

<p>Error bars stand for standard errors. Bar with the same letters show no statistically significant differences at p≤0.05. n = 8.</p

NO_3^--N (A) and soluble sugar (B) contents content in the leaves Error bars stand for standard errors.

<p>Bar with this asterisk (*) symbol shows statistically significant differences at <i>p</i>≤0.05, n = 8.</p

(A) Root and shoot fresh biomass of lettuce plants grown for 30 days in potting soil, treated with 0 (control)-1000 mg·kg^-1 CeO₂ NPs. (B) Root and shoot dry biomass of lettuce plants grown for 30 days in potting soil treated with 0 (control)-1000 mg·kg^-1 CeO₂ NPs.

<p>Error bars stand for standard errors. Bar with this asterisk (*) symbol shows statistically significant differences at p≤0.05. n = 8.</p

SOD and POD activities and MDA levels in the roots and shoots of of lettuce plants

<p>Error bars stand for standard errors. Bar with this asterisk (*) symbol shows statistically significant differences at <i>p</i>≤0.05.</p