Synthesis of the Tetracyclic Scaffolds of the Endiandric Acids Through Iterative Cross-Coupling

A number of natural products isolated from plants in the Endiandra and Beilschmiedia genera contain complex tetracyclic scaffolds, which are believed to be made from linear polyene precursors that undergo electrocyclization cascades. This thesis describes a concise, biomimetic and modular synthetic route to the two types of tetracyclic scaffolds that are found in these natural products. Our strategy employs iterative cross-couplings to prepare a bicyclic intermediate, which can easily be converted into each tetracycle in two more steps. This work features a novel application of Marty Burke’s iterative Suzuki-coupling method for polyene synthesis, and it represents a significant improvement over previous syntheses of endiandric acid analogs

Identification of a Kitaev Quantum Spin Liquid by Magnetic Field Angle Dependence

Quantum spin liquids realize massive entanglement and fractional quasiparticles with localized spins, proposed as an avenue for quantum science and technology. In particular, topological quantum computations are suggested in the non-abelian phase of Kitaev quantum spin liquid with Majorana fermions, and detection of Majorana fermions is one of the most outstanding problems in modern condensed matter physics. Here, we propose a concrete way to identify the non-abelian Kitaev quantum spin liquid by magnetic field angle dependence. Topologically protected critical lines exist on a plane of magnetic field angles, and their shapes are determined by microscopic Hamiltonian information. A chiral spin operator plays a key role to detect the critical lines varying with magnetic field angles, and experimental criteria for the non-abelian spin liquid state are provided. Our proposal may be employed as a new route to probe a non-abelian quantum spin liquid in addition to the half-quantization of thermal Hall conductivity.Comment: 12 pages, 8 figures, 2 table

Morphological Studies on Seeds of Scrophulariaceae s.l. and Their Systematic Significance

This study employed scanning electron microscopy and light microscopy to observe seed surface micromorphology and seed coat anatomy in the Scrophulariaceae s.l. to investigate seed characters of taxonomic importance. Seeds of 41 taxa corresponding to 13 genera of the family were carefully investigated. Seeds were minute and less than or slightly larger than 1 millimeter in length except for Melampyrum and Pedicularis species. The seed shape ranged from elliptical to broad elliptical and ovoid. In the studied species the surface sculpture was predominantly reticulate-striate, regular reticulate, sometimes colliculate, and rugose, or - rarely - ribbed, as in Lindernia procumbens and Paulownia coreana. Seed coats comprised the epidermis and the endothelium. Nevertheless, in all Melampyrum and some Veronica species the seed coat was very poorly represented and only formed by a papery layer of epidermis. According to correspondence analysis (CA) and unweighted pair group method with arithmetic mean (UPGMA) based cluster analysis the close affinities among the species of Scrophularia were well supported by their proximity to one another. Similarly, the proximity of Melampyrum species and Pedicularis species cannot be denied. In contrast, Veronica species were divided into two groups in CA plots and even three in the UPGMA tree. Regardless of the limited range taxa considered we found that similarities and differences in seed morphology between different genera could help us to understand the systematic relationships involved

対外関係からみた鎌倉時代

学位の種別:課程博士University of Tokyo(東京大学

Evaluations of Interactive Learning Tools Among Engineering Students: Effects of Grit and Gender

This study explores what determines engineering students’ evaluations of interactive learning tools (ILTs). Engineering students (n = 323) from large U.S. universities who had used McGraw-Hill’s SmartBook and Connect participated in the study. This study confirms that grit and gender are important factors in opinions and attitudes toward such tools. Specifically, among males, those with higher grit found ILTs as more useful and usable. Moreover, higher levels of grit were related to favorable attitudes toward ILTs. Interesting to note was that females reported more favorable evaluations on ILTs overall. These findings suggest strategies for the use of interactive learning tools for engineering students to succeed. Implications and recommendations for future research will also discussed

Prediction of abundance of arthropods according to climate change scenario RCP 4.5 and 8.5 in South Korea

AbstractAbundance and diversity of arthropods were projected according to climate warming in South Korea. The taxa highly linked with temperature were selected for the projection. The values of abundance and richness were estimated using the mean values of abundance and richness in each temperature range. Temperature changes were based on the RCP (Representative Concentration Pathway) 4.5 and RCP 8.5, and the abundance and richness during two periods (2011 -2015, 2056 -2065) were projected. From these projected results, change of other common taxa (> 1% occurrence) were qualitatively predicted (i.e., decrease or increase). The projections showed that 45 of a total of 73 taxa will increase, 6 will change a little and 24 will decrease: the number of taxa that were expected to increase was two times more than the number of taxa that were expected to decrease. However, the overall abundance and diversity of arthropods were expected to decline as the temperature rises