9,461 research outputs found

    Competition between structural distortion and magnetic moment formation in fullerene C20_{20}

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    We investigated the effect of on-site Coulomb interactions on the structural and magnetic ground state of the fullerene C20_{20} based on density-functional-theory calculations within the local density approximation plus on-site Coulomb corrections (LDA+UU). The total energies of the high symmetry (IhI_{h}) and distorted (D3dD_{3d}) structures of C20_{20} were calculated for different spin configurations. The ground state configurations were found to depend on the forms of exchange-correlation potentials and the on-site Coulomb interaction parameter UU, reflecting the subtle nature of the competition between Jahn-Teller distortion and magnetic instability in fullerene C20_{20}. While the non-magnetic state of the distorted D3dD_{3d} structure is robust for small UU, a magnetic ground state of the undistorted IhI_{h} structure emerges for UU larger than 4 eV when the LDA exchange-correlation potential is employed.Comment: 4 figures, 1 tabl

    Structural dynamics and divergence of the polygalacturonase gene family in land plants

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    A distinct feature of eukaryotic genomes is the presence of gene families. The polygalacturonase (PG) (EC3.2.1.15) gene family is one of the largest gene families in plants. PG is a pectin-digesting enzyme with a glycoside hydrolase 28 domain. It is involved in numerous plant developmental processes. The evolutionary processes accounting for the functional divergence and the specialized functions of PGs in land plants are unclear. Here, phylogenetic and gene structure analysis of PG genes in algae and land plants revealed that land plant PG genes resulted from differential intron gain and loss, with the latter event predominating. PG genes in land plants contained 15 homologous intron blocks and 13 novel intron blocks. Intron position and phase were not conserved between PGs of algae and land plants but conserved among PG genes of land plants from moss to vascular plants, indicating that the current introns in the PGs in land plants appeared after the split between unicellular algae and multicelluar land plants. These findings demonstrate that the functional divergence and differentiation of PGs in land plants is attributable to intronic loss. Moreover, they underscore the importance of intron gain and loss in genomic adaptation to selective pressure

    Analysis of Core Technologies and Implementation Services for Smart City

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    Smart City Platform is a software that optimally allocates resources and provides services to citizens by utilizing ICT technologies such as artificial intelligence, IoT, virtual reality, augmented reality, and 5G mobile communication to solve various urban problems occurring in the city.In order to implement the Smart City environment, basic platform technologies such as artificial intelligence, big data, network, Internet of Things(IoT) and Cloud computing are essential.In this paper, we used the big data analysis tool ‘BigKinds’ to lookup the topic 'Smart City Technology' and 'Smart City IoT' in news, editorials and quotations. After analyzing them, we then derived the core technologies needed in building a Smart City. Furthermore, we introduced the concept of the basic Smart City technologies and then deduced implications and drew a conclusion by analyzing both the local and foreign Smart City construction services. In addition, it compared and analyzed the core technologies for supporting services in various smart cities.The Smart City’s basic technologies and service analysis can be utilized by the local government to effectively establish policies and technology strategies in the Smart City industry
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