Tokyo University of Science

About: Tokyo University of Science is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 15800 authors who have published 24147 publications receiving 438081 citations. The organization is also known as: Tōkyō Rika Daigaku & Science University of Tokyo.

New Insight into Structural Evolution in Layered NaCrO2 during Electrochemical Sodium Extraction

Abstract: Electrochemical properties and structural changes during charge for NaCrO2, whose structure is classified as α-NaFeO2 type layered polymorph (also O3-type following the Delmas’ notation), are examined as a positive electrode material for nonaqueous Na-ion batteries. NaCrO2 delivers initial discharge capacity of 110 mAh g–1 at 1/20C rate in the voltage range of 2.5–3.6 V based on reversible Cr3+/Cr4+ redox without oxidation to hexavalent chromium ions, while the initial discharge capacity is only 9 mAh g–1 when cutoff voltage is set to 4.5 V. Results from ex-situ X-ray diffraction, X-ray absorption spectroscopy, and DFT calculations reveal that the irreversible phase transition occurs after sodium extraction by charging over a voltage plateau at 3.8 V associated with the lattice shrinkage along the c-axis in the case of x > 0.5 in Na1–xCrO2, which originates from the migration of chromium ions from octahedral sites in CrO2 slabs to both tetrahedral and octahedral sites in interslab layer. The irreversible ...

New result in the production and decay of an isotope, 278113, of the 113th element

Abstract: An isotope of the 113th element, i.e., 278 113, was produced in a nuclear reaction with a 70 Zn beam on a 209 Bi target. We observed six consecutive α-decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector under an extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of 262 Db and 258 Lr in both decay energies and decay times. This indicates that the present decay chain consisted of 278 113, 274 Rg ( Z =111), 270 Mt ( Z =109), 266 Bh ( Z =107), 262 Db ( Z =105), and 258 Lr ( Z =103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads to the unambiguous production and identification of the isotope 278 113 of the 113th element.

Effective gravitational couplings for cosmological perturbations in generalized Proca theories

Abstract: We consider the finite interactions of the generalized Proca theory including the sixth-order Lagrangian and derive the full linear perturbation equations of motion on the flat Friedmann-Lemaitre-Robertson-Walker background in the presence of a matter perfect fluid By construction, the propagating degrees of freedom (besides the matter perfect fluid) are two transverse vector perturbations, one longitudinal scalar, and two tensor polarizations The Lagrangians associated with intrinsic vector modes neither affect the background equations of motion nor the second-order action of tensor perturbations, but they do give rise to non-trivial modifications to the no-ghost condition of vector perturbations and to the propagation speeds of vector and scalar perturbations We derive the effective gravitational coupling $G_{\rm eff}$ with matter density perturbations under a quasi-static approximation on scales deep inside the sound horizon We find that the existence of intrinsic vector modes allows a possibility for reducing $G_{\rm eff}$ In fact, within the parameter space, $G_{\rm eff}$ can be even smaller than the Newton gravitational constant $G$ at the late cosmological epoch, with a peculiar phantom dark energy equation of state (without ghosts) The modifications to the slip parameter $\eta$ and the evolution of growth rate $f\sigma_8$ are discussed as well Thus, dark energy models in the framework of generalized Proca theories can be observationally distinguished from the $\Lambda$CDM model according to both cosmic growth and expansion history Furthermore, we study the evolution of vector perturbations and show that outside the vector sound horizon the perturbations are nearly frozen and start to decay with oscillations after the horizon entry

Brane-world stars with a solid crust and vacuum exterior

Abstract: The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with a vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all the elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, and all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness inversely proportional to both the brane tension and the radius R of the star, i.e. . This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accretion disks.

Generalized network Voronoi diagrams: Concepts, computational methods, and applications

Abstract: In the real world, there are many phenomena that occur on a network or alongside a network; for example, traffic accidents on highways and retail stores along streets in an urbanized area. In the literature, these phenomena are analysed under the assumption that distance is measured with Euclidean distance on a plane. This paper first examines this assumption and shows an empirical finding that Euclidean distance is significantly different from the shortest path distance in an urbanized area if the distance is less than 500 m. This implies that service areas in urbanized areas cannot be well represented by Voronoi diagrams defined on a plane with Euclidean distance, termed generalized planar Voronoi diagrams. To overcome this limitation, second, this paper formulates six types of Voronoi diagrams defined on a network, termed generalized network Voronoi diagrams, whose generators are given by points, sets of points, lines and polygons embedded in a network, and whose distances are given by inward/outward distances, and additively/multiplicatively weighted shortest path distances. Third, in comparison with the generalized planar Voronoi diagrams, the paper empirically shows that the generalized network Voronoi diagrams can more precisely represent the service areas in urbanized areas than the corresponding planar Voronoi diagrams. Fourth, because the computational methods for constructing the generalized planar Voronoi diagrams in the literature cannot be applied to constructing the generalized network Voronoi diagrams, the paper provides newly developed efficient algorithms using the 'extended' shortest path trees. Last, the paper develops user-friendly tools (that are included in SANET, a toolbox for spatial analysis on a network) for executing these computational methods in a GIS environment.