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61.
Hannah DC Dunn NJ Ithurria S Talapin DV Chen LX Pelton M Schatz GC Schaller RD 《Physical review letters》2011,107(17):177403
We report heat dissipation times in semiconductor nanocrystals of CdSe. Specifically, a previously unresolved, subnanosecond decay component in the low-temperature photoluminescence decay dynamics exhibits longer decay lifetimes (tens to hundreds of picoseconds) for larger nanocrystals as well as a size-independent, ~25-meV spectral shift. We attribute the fast relaxation to transient phonon-mediated relaxation arising from nonequilibrium acoustic phonons. Following acoustic phonon dissipation, the dark exciton state recombines more slowly via LO-phonon assistance resulting in the observed spectral shift. The measured relaxation time scales agree with classical calculations of thermal diffusion, indicating that interfacial thermal conductivity does not limit thermal transport in these semiconductor nanocrystal dispersions. 相似文献
62.
We propose a new protocol for quantum anonymous voting having serious advantages over the existing protocols: it protects both the voters from a curious tallyman and all the participants from a dishonest voter in unconditional way. The central idea of the protocol is that the ballots are given back to the voters after the voting process, which gives a possibility for two voters to check the anonymity of the vote counting process by preparing a special entangled state of two ballots. Any attempt of cheating from the side of the tallyman results in destroying the entanglement, which can be detected by the voters. 相似文献
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Dmitri V. Alekseevsky Andreas Kriegl Mark Losik Peter W. Michor 《Annali di Matematica Pura ed Applicata》2007,186(1):25-58
We investigate discrete groups G of isometries of a complete connected Riemannian manifold M which are generated by reflections, in particular those generated by disecting reflections. We show that these are Coxeter
groups, and that the orbit space M/G is isometric to a Weyl chamber C which is a Riemannian manifold with corners and certain angle conditions along intersections of faces. We can also reconstruct
the manifold and its action from the Riemannian chamber and its equipment of isotropy group data along the faces. We also
discuss these results from the point of view of Riemannian orbifolds.
Mathematics Subject Classification Primary 51F15, 53C20, 20F55, 22E40 相似文献
68.
Alexey P. Ilyin Julia N. Peregudova Elena B. Poutsykina Dmitri V. Kravchenko 《Tetrahedron letters》2006,47(15):2649-2653
We present a convenient synthesis of heterocyclic scaffolds using a novel modification of four-component Ugi condensation. Two complementary variants of this useful synthetic strategy provide an efficient one-step assembly of four novel pharmaceutically relevant (hetero)aryl-fused 1,4-oxazepines with different substituents’ profile. 相似文献
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In this work we present a composite model, which combines the approach of Poisson's function with the filament theory and requires three material parameters. We also suggest the form for a strain-energy function that approximates the constitutive equations of the composite model. Furthermore, a simple asymptotic analysis allows us to reduce the number of material constants to only two, thus, forming a new filament model. The predictive capability of the two models to reproduce the mechanical behaviour of elastomeric materials in deformation experiments is evaluated against the extensive data of Kawabata et al. (Macromolecules 14 (1981) 154). The models give excellent agreement in not only uniaxial and equibiaxial but also non-equibiaxial extension. Although being rather more simplistic in comparison with some successful network models involving non-Gaussian chain statistics, the two models conform much more closely to the classical experimental data of Treloar (Trans. Faraday Soc. 40 (1944) 59). 相似文献