72 research outputs found
Tetravalent edge-transitive Cayley graphs with odd number of vertices
AbstractA characterisation is given of edge-transitive Cayley graphs of valency 4 on odd number of vertices. The characterisation is then applied to solve several problems in the area of edge-transitive graphs: answering a question proposed by Xu [Automorphism groups and isomorphisms of Cayley graphs, Discrete Math. 182 (1998) 309–319] regarding normal Cayley graphs; providing a method for constructing edge-transitive graphs of valency 4 with arbitrarily large vertex-stabiliser; constructing and characterising a new family of half-transitive graphs. Also this study leads to a construction of the first family of arc-transitive graphs of valency 4 which are non-Cayley graphs and have a ‘nice’ isomorphic 2-factorisation
Low compressible noble metal carbides with rock-salt structure: ab initio total energy calculations of the elastic stability
We have systematically studied the mechanical stability of all noble metal
carbides with the rock-salt structure by calculating their elastic constants
within the density function theory scheme. It was found that only four carbides
(RuC, PdC, AgC and PtC) are mechanically stable. In particular, we have shown
that RuC, PdC, and PtC have very high bulk modulus, which has been remarkably
observed by the most recent experiment for the case of PtC. From the calculated
density of states, we can conclude that these compounds are metallic, like the
conventional group IV and group V transition metal carbides.Comment: Appl. Phys. Lett. 89, 071913 (2006
Potential super-hard Osmium di-nitride with fluorite structure: First-principles calculations
We have performed systematic first-principles calculations on di-carbide,
-nitride, -oxide and -boride of platinum and osmium with the fluorite
structure. It is found that only PtN, OsN and OsO are
mechanically stable. In particular OsN has the highest bulk modulus of
360.7 GPa. Both the band structure and density of states show that the new
phase of OsN is metallic. The high bulk modulus is owing to the strong
covalent bonding between Os 5\textit{d} and N 2\textit{p} states and the dense
packed fluorite structure.Comment: Phys. Rev. B 74,125118 (2006
MR and CT findings of cyst degeneration of sphenoid bone in McCune-Albright syndrome: a case report
© 2009 Li et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Enhanced inhibition of Avian leukosis virus subgroup J replication by multi-target miRNAs
<p>Abstract</p> <p>Background</p> <p>Avian leukosis virus (ALV) is a major infectious disease that impacts the poultry industry worldwide. Despite intensive efforts, no effective vaccine has been developed against ALV because of mutations that lead to resistant forms. Therefore, there is a dire need to develop antiviral agents for the treatment of ALV infections and RNA interference (RNAi) is considered an effective antiviral strategy.</p> <p>Results</p> <p>In this study, the avian leukosis virus subgroup J (ALV-J) proviral genome, including the <it>gag </it>genes, were treated as targets for RNAi. Four pairs of miRNA sequences were designed and synthesized that targeted different regions of the <it>gag </it>gene. The screened target (i.e., the <it>gag </it>genes) was shown to effectively suppress the replication of ALV-J by 19.0-77.3%. To avoid the generation of escape variants during virus infection, expression vectors of multi-target miRNAs were constructed using the multi-target serial strategy (against different regions of the <it>gag</it>, <it>pol</it>, and <it>env </it>genes). Multi-target miRNAs were shown to play a synergistic role in the inhibition of ALV-J replication, with an inhibition efficiency of viral replication ranging from 85.0-91.2%.</p> <p>Conclusion</p> <p>The strategy of multi-target miRNAs might be an effective method for inhibiting ALV replication and the acquisition of resistant mutations.</p
The Schur Multiplicative and Harmonic Convexities for Three Classes of Symmetric Functions
We investigate the Schur harmonic convexity for two classes of symmetric functions and the Schur multiplicative convexity for a class of symmetric functions by using a new method and generalizing previous result. As applications, we establish some inequalities by use of the theory of majorization, in particular, and we give some new geometric inequalities in the n-dimensional space
The genus Clavariadelphus (Clavariadelphaceae, Gomphales) in China
Clavariadelphus species (Clavariadelphaceae, Gomphales) in China were examined using morphology, molecular phylogenetic analyses of ITS data and chemical reactions. Eleven taxa were identified in China, including four species known previously to occur in China (C. griseoclavus, C. ligula, C. sachalinensis and C. yunnanensis), two new record species from China (C. elongatus and C. himalayensis), four novel species (C. alpinus, C. amplus, C. gansuensis and C. khinganensis) and one species that could not be described due to the paucity of material. Finally, we also provided a taxonomic key for the identification of Clavariadelphus species in China
Spin-polarized transport in zigzag graphene nanoribbons adsorbing nonmagnetic atomic chain
The spin-polarized transport properties of nonmagnetic (metallic Al and nonmetallic C) atomic chains adsorbed on zigzag graphene nanoribbons (ZGNRs) are investigated by the density functional theory (DFT) combined with the nonequilibrium Green’s function method. We find that the spin polarization of ZGNRs is sensitive to the adsorption sites and atomic types of the chains. As an Al chain is adsorbed on the middle of ZGNR, no spin-polarized transport arises. As the Al chain is adsorbed on the edge of ZGNR, high spin polarization is produced around the Fermi level. The different transport behaviors are originated from the fact that the edge adsorption of Al chain breaks the magnetization symmetry of two edges while the middle adsorption of Al chain only modifies the magnetizations of two edges equally. More prominent spin polarization is generated as a C chain is adsorbed on the edge of ZGNR. The complete spin polarization emerges not only around the Fermi level but also far from the Fermi level, owing to the edge states and the localized states. These results indicate that one can effectively modulate the spin-polarized transports of ZGNRs through adsorbing different nonmagnetic atomic chains
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