Waseda University

About: Waseda University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Large Hadron Collider. The organization has 24220 authors who have published 46859 publications receiving 837855 citations. The organization is also known as: Waseda daigaku & Sōdai.

Polaron Ordering in Low-Doping La 1 − x Sr x MnO 3

Abstract: We have found a polaron ordered phase in low-doping rate ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ ( $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.10$ and 0.15) by neutron scattering study. The onset temperature of the polaron order coincides with the point of resistivity upturn. The periodicity of the hole lattice is commensurate to the structural lattice translation, the unit cell being given by $2a\ifmmode\times\else\texttimes\fi{}2b\ifmmode\times\else\texttimes\fi{}4c$ in cubic perovskite basis. The nominal hole concentration corresponding to this periodicity is $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.125$. The polaron lattice seems to have the tendency to lock into this commensurate structure within a finite concentration range around the nominal value of $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.125$.

F-regular and F-pure rings vs. log terminal and log canonical singularities

Abstract: In this paper, we investigate the relationship of F-regular (resp. F-pure) rings and log terminal (resp. log canonical) singularities. Also, we extend the notions of F-regularity and F-purity to "F-singularities of pairs." The notions of F-regular and F-pure rings in characteristic $p>0$ are characterized by a splitting of the Frobenius map, and define some classes of rings having "mild" singularities. On the other hand, there are notions of log terminal and log canonical singularities defined via resolutions of singularities in characteristic zero. These are defined also for pairs of a normal variety and a $\Bbb Q$-divisor $\Delta$ on it, and play an important role in birational algebraic geometry. As an analog of these singularities of pairs in characteristic zero, we define the notions of "F-singularities of pairs," namely strong F-regularity, divisorial F-regularity and F-purity for a pair $(A,\Delta)$ of a normal ring $A$ of characteristic $p > 0$ and an effective $\Bbb Q$-divisor $\Delta$ on $Y = Spec A$. The main theorem of this paper asserts that, if $K_Y + \Delta$ is $\Bbb Q$-Cartier, then the above three variants of F-singularitiesof pairs imply KLT, PLT and LC properties, respectively. We also prove some results for F-singularities of pairs which are analoguous to singularities of pairs in characteristic zero.

Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

Abstract: Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

Molecular Evolution of Multiple Forms of Kisspeptins and GPR54 Receptors in Vertebrates

Abstract: Kisspeptin and its receptor GPR54 play important roles in mammalian reproduction and cancer metastasis. Because the KiSS and GPR54 genes have been identified in a limited number of vertebrate species, mainly in mammals, the evolutionary history of these genes is poorly understood. In the present study, we have cloned multiple forms of kisspeptin and GPR54 cDNAs from a variety of vertebrate species. We found that fish have two forms of kisspeptin genes, KiSS-1 and KiSS-2, whereas Xenopus possesses three forms of kisspeptin genes, KiSS-1a, KiSS-1b, and KiSS-2. The nonmammalian KiSS-1 gene was found to be the ortholog of the mammalian KiSS-1 gene, whereas the KiSS-2 gene is a novel form, encoding a C-terminally amidated dodecapeptide in the Xenopus brain. This study is the first to identify a mature form of KiSS-2 product in the brain of any vertebrate. Likewise, fish possess two receptors, GPR54-1 and GPR54-2, whereas Xenopus carry three receptors, GPR54-1a, GPR54-1b, and GPR54-2. Sequence identity and geno...