Low-Temperature X-ray Crystal Structure Analysis of the Cage-Structured Compounds MBe13 (M = La, Sm, and U)

The beryllides MBe13 (M = rare earths and actinides) crystallize in a NaZn13-type cubic structure, which can be categorized as a cage-structured compound. In this study, powder X-ray diffraction measurements have been performed on LaBe13, SmBe13, and UBe13 in the temperature range between 7 and 300 K in order to investigate their crystallographic characteristics systematically. They keep the NaZn13-type cubic structure down to the lowest temperature. We estimated their Debye temperature to be 600 - 750 K from analyses of the temperature dependence of a lattice parameter, being in good agreement with the values reported previously. Rietveld refinements on the obtained powder patterns revealed that the M atom in the 8a site is located in an almost ideal snub cube formed by 24 Be atoms in the 96i site, whose caged structure is unchanged even at the low temperatures. In addition, it is argued from the temperature variation of an isotropic mean-square displacement parameter that the MBe13 compounds commonly have a low-energy phonon mode, which can be described by a model assuming an Einstein oscillation of the M atom with a characteristic temperature of ~ 160 K.Comment: 8 pages with 6 figures and 2 table

Neutron Diffraction Study on Single-crystalline UAu2{_2}Si2_2

Magnetic structure of tetragonal UAu$_2$Si$_2$ was investigated by single-crystal neutron diffraction experiments. Below $T_{\rm N}$ = 20 K it orders antiferromagnetically with a propagation vector of $k = (2/3, 0, 0)$ and magnetic moments of uranium ions pointing along the tetragonal $c$-axis. Weak signs of the presence of a ferromagnetic component of magnetic moment were traced out.Taking into account a group theory calculation and experimental results of magnetization and $^{29}$Si-NMR, the magnetic structure is determined to be a squared-up antiferromagnetic structure, with a stacking sequence ($+ + -$) of the ferromagnetic $ac$-plane sheets along the $a$-axis. This result highlights similar magnetic correlations in UAu$_2$Si$_2$ and isostructural URu$_2$Si$_2$.Comment: 7 pages, 7 figure

ファイトプラズマの宿主転換に伴う遺伝子の発現および機能に関する研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 難波 成任, 法政大学教授 大島 研郎, 東京大学准教授 岩田 洋佳, 東京大学准教授 松尾 隆嗣, 東京大学准教授 山次 康幸University of Tokyo(東京大学

Quantitative evaluation of protocorm growth and fungal colonization in Bletilla striata (Orchidaceae) reveals less-productive symbiosis with a non-native symbiotic fungus

Quantitative evaluation of symbiotic cells in Pecteilis radiata protocorm. (a) Symbiotic cells with hyphal coils in P. radiata protocorm. Scale bars, 50 Οm. (b) Ratio of the number of symbiotic cells at each stage in a symbiotic protocorm. Each value represents the average number of symbiotic cells in ten protocorms. The experiments were repeated six times with similar results. (PDF 959 kb

Strain-Rate and Temperature Dependences of Deformation Behavior of AZ61Mg Alloy Processed by Multi-directional Forging Under Decreasing Temperature Conditions

金沢大学理工研究域機械工学系Strain-rate and temperature dependences of deformation behavior of ultrafine-grained (UFGed) AZ61Mg alloy were examined. For this purpose, AZ61Mg alloy specimens were subjected to multi-directional forging (MDFing) under decreasing temperature conditions to have various grain sizes. The average grain sizes attained by MDFing to 1, 3, 6 and 9 passes were approximately 8, 2, 0.5 and 0.3 μm, respectively. A superior balance of the mechanical properties of strength and ductility at room temperature was achieved by MDFing to three passes and over. The strain-rate sensitivity of mechanical properties of the MDFed specimens increased with decreasing grain size. The specimens with grain sizes of 0.5 and 0.3 μm (0.5 or 0.3 specimen) exhibited stronger strain-rate and temperature dependences of total elongation than those with grain sizes of 8 and 2 μm (8 or 2 specimen). This can be partially ascribed to grain-boundary sliding, since an AFM observation revealed the occurrence of room-temperature grain-boundary sliding in the 0.3 specimen. The activation volume V* for the 8, 2 and 0.5 specimen increased with increasing temperature, while the 0.3 specimen exhibited an inverse temperature dependence of V*. This suggests a change in deformation mechanism with decreasing grain size as well as the occurrence of grain-boundary sliding. © 2017 The Minerals, Metals & Materials Society and ASM InternationalEmbargo Period 12 monthsThe final publication is available at www.springerlink.com/article/10.1007/s11661-017-4303-

Quarkyonic Matter and Chiral Symmetry Breaking

The appearance of a new phase of QCD, Quarkyonic Matter in the limit of large number of colors is studied within Nambu-Jona-Lassinio effective chiral model coupled to the Polyakov loop. The interplay of this novel QCD phase with chiral symmetry restoration and color deconfinement is discussed. We find that at vanishing temperature and at large $N_c$, the quarkyonic transition occurs at densities only slightly lower than that expected for the chiral transition. This property is also shown to be valid at finite temperature if the temperature is less than that of deconfinement. The position and $N_c$-dependence of chiral critical end point is also discussed.Comment: 18 pages, 8 figure

A Chemometrics-driven Strategy for the Bioactivity Evaluation of Complex Multicomponent Systems and the Effective Selection of Bioactivity-predictive Chemical Combinations

Although understanding their chemical composition is vital for accurately predicting the bioactivity of multicomponent drugs, nutraceuticals, and foods, no analytical approach exists to easily predict the bioactivity of multicomponent systems from complex behaviors of multiple coexisting factors. We herein represent a metabolic profiling (MP) strategy for evaluating bioactivity in systems containing various small molecules. Composition profiles of diverse bioactive herbal samples from 21 green tea extract (GTE) panels were obtained by a high-throughput, non-targeted analytical procedure. This employed the matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) technique, using 1,5-diaminonaphthalene (1,5-DAN) as the optical matrix for detecting GTE-derived components. Multivariate statistical analyses revealed differences among the GTEs in their antioxidant activity, oxygen radical absorbance capacity (ORAC). A reliable bioactivity-prediction model was constructed to predict the ORAC of diverse GTEs from their compositional balance. This chemometric procedure allowed the evaluation of GTE bioactivity by multicomponent rather than single-component information. The bioactivity could be easily evaluated by calculating the summed abundance of a few selected components that contributed most to constructing the prediction model. 1,5-DAN-MALDI-MS-MP, using diverse bioactive sample panels, represents a promising strategy for screening bioactivity-predictive multicomponent factors and selecting effective bioactivity-predictive chemical combinations for crude multicomponent systems