Aoyama Gakuin University

About: Aoyama Gakuin University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Superconductivity & Thin film. The organization has 3494 authors who have published 6419 publications receiving 115648 citations. The organization is also known as: Aoyama gakuin daigaku.

Structural and spectroscopic properties of a copper(I)-bis(N-heterocyclic)carbene complex.

Abstract: The structural and spectroscopic properties of a Cu(I) complex bearing a methylene-linked bis(N-heterocyclic carbene) ligand, [Cu2(μ-Me-mbim)2](PF6)2 were investigated. X-ray single crystal structure analysis revealed that the complex is binuclear similar to the corresponding silver(I) complex. In [Cu2(μ-Me-mbim)2](PF6)2, cation–π interaction between copper and the adjacent carbene carbon is observed. On the other hand, the copper–copper interaction is very weak in the crystal and almost negligible in solution. The absorption spectrum of [Cu2(μ-Me-mbim)2](PF6)2 in methanol shows a strong absorption band (e = 23 000 dm3 mol−1 cm−1) and a weaker shoulder (e = 6200 dm3 mol−1 cm−1) at 261 nm and 300 nm, respectively. From molecular orbital calculations using TD-DFT, these absorption bands are assigned to the metal-centered transitions with some contribution from the NHC orbitals. The powdered sample of [Cu2(μ-Me-mbim)2](PF6)2 shows bright blue-green phosphorescence with a high quantum yield (43%). The phosphorescence is of dual-emission character at room temperature with peak maxima at 374 nm and 482 nm whereas it changes to a single emission band centered around 500 nm at 77 K. Molecular orbital calculations indicate that the luminescence derives from the triplet MC and MLCT mixed excited states. A methanolic solution of [Cu2(μ-Me-mbim)2](PF6)2 shows yellow-green phosphorescence with a peak maximum at 542 nm. Unlike in the solid state, no dual-emission was observed. These results suggest that the dual emission is caused by differences in the contribution of metal–metal interactions at room temperature in the solid state. The differences in the absorption and emission properties between [Cu2(μ-Me-mbim)2](PF6)2 and the related Cu(I)–diphosphine complex, [Cu2(μ-dcpm)2](BF4)2 are discussed.

Deconfinement of vortices with continuously variable fractions of the unit flux quanta in two-gap superconductors

Abstract: We propose a new stage of confinement-deconfinement transition, which can be observed in laboratory. In two-gap superconductors (SCs), two kinds of vortex exist and each of them carries a continuously variable fraction of the unit flux quanta Φ0=hc/2e. The confined state of these two is a usual vortex and stable in the low-temperature region of the system under a certain magnetic field above Hc1. We see an analogy to quarks in a charged pion. An entropy gain causes two fractional vortices to be deconfined above a certain temperature.

Resource Endowments and Agricultural Development: Africa versus Asia

Abstract: This chapter aims to examine the sources of agricultural stagnation/ deterioration in Sub-Saharan Africa by contrasting it with the agricultural growth experience in Asia, and East Asia in particular. An important and well-documented feature of the East Asian model of economic development is the considerable success of the countries concerned in expanding their agricultural sector. This success enabled them to provide more or less regular employment to a growing rural population before urban industrialization was advanced enough to absorb large numbers of workers (Fei, Ranis and Kuo, 1979; Morley, 1982, ch. 11). In the case of some countries (most notably, Japan and Taiwan), expansion of rural employment opportunities and incomes was greatly helped by a decentralized pattern of industrialization that resulted in the development of numerous rural industries (Smith, 1959; Ho, 1979). Moreover, since food supply increased rapidly, instead of being diverted to food imports, foreign exchange earnings could be reserved for importing capital and intermediate goods needed by modern industries.

Synthesis of Belt- and Möbius-Shaped Cycloparaphenylenes by Rhodium-Catalyzed Alkyne Cyclotrimerization

Abstract: A belt-shaped [8]cycloparaphenylene (CPP) and an enantioenriched Mobius-shaped [10]CPP have been synthesized by high-yielding rhodium-catalyzed intramolecular cyclotrimerizations of a cyclic dodecayne and a pentadecayne, respectively. This Mobius-shaped [10]CPP possesses stable chirality and isolated with high enantiomeric purity. It is evident from the reaction Gibbs energy calculation that the above irreversible cyclotrimerizations are highly exothermic; therefore establishing that the intramolecular alkyne cyclotrimerization is a powerful route to strained cyclic molecular strips.

Electronic Structure Analyses of Sn-doped In2O3

Abstract: Electronic structures of Sn-doped In2O3 (ITO) have been investigated for the first time by using a first-principles calculation method based on the density functional theory. Calculated partial density of states (PDOS) analyses showed that a Sn atom substituted for an indium one formed three impurity bands with s-like symmetry, the second band of the three bands overlapped the conduction band of In2O3, and the Fermi energy of ITO was captured in this impurity band. The PDOS analyses also revealed that the substitution of a Sn atom did not significantly destroy the shape of density of states around the bottom of the conduction band, which gave a physical foundation for the Burstein-Moss shift model used up to now. Carrier generation mechanism and past experimental results, such as those of X-ray photoelectron spectroscopy, temperature dependency of electrical conductivity and carrier-concentration dependency of optical effective mass of ITO, are discussed based on the present theoretical calculation results.