排序方式: 共有21条查询结果,搜索用时 15 毫秒
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Polacco G Stastna J Biondi D Antonelli F Vlachovicova Z Zanzotto L 《Journal of colloid and interface science》2004,280(2):366-373
Asphalt is known to be a colloidal suspension in which asphaltenes are covered by a stabilizing phase of polar resins and form complex micelles that are dispersed in the oily maltenic phase. In order to enhance its mechanical properties (e.g., in road paving), asphalts are often loaded with polymeric materials, thereby obtaining blends that can have different physical or chemical structures, depending on the composition of the added polymer. Asphalts modified by the addition of reactive ethylene terpolymers were prepared and their dielectric and rheological properties were measured both before and after a cure at high temperature. Even if it is not possible to determine the exact nature of the chemical interactions between asphalt and polymer, master curves obtained from dynamic data clearly show that during the cure the material tends to the behavior of a cross-linked network. 相似文献
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Giovanni Polacco Pavel K?í? Jiri Stastna Ludovit Zanzotto 《European Polymer Journal》2008,44(11):3512-3521
The effect of the addition of clay as a third component in polymer modified asphalts has been investigated. After a preliminary investigation on the binary asphalt/clay and polymer/clay blends, the tertiary blends were prepared by adding the clay and polymer to the asphalt, either separately or in the form of a premixed master batch. Intercalated nanocomposites with comparable interlayer distances and glass transition temperatures were obtained in both cases. However, the results show that the mixing procedure significantly affected the final rheological properties. The master curves built in the linear viscoelastic range and represented in both the frequency and the temperature domains help to visualize and evaluate such differences. 相似文献
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V. N. Strocov X. Wang M. Shi M. Kobayashi J. Krempasky C. Hess T. Schmitt L. Patthey 《Journal of synchrotron radiation》2014,21(1):32-44
Soft‐X‐ray angle‐resolved photoelectron spectroscopy (ARPES) with photon energies around 1 keV combines the momentum space resolution with increasing probing depth. The concepts and technical realisation of the new soft‐X‐ray ARPES endstation at the ADRESS beamline of SLS are described. The experimental geometry of the endstation is characterized by grazing X‐ray incidence on the sample to increase the photoyield and vertical orientation of the measurement plane. The vacuum chambers adopt a radial layout allowing most efficient sample transfer. High accuracy of the angular resolution is ensured by alignment strategies focused on precise matching of the X‐ray beam and optical axis of the analyzer. The high photon flux of up to 1013 photons s?1 (0.01% bandwidth)?1 delivered by the beamline combined with the optimized experimental geometry break through the dramatic loss of the valence band photoexcitation cross section at soft‐X‐ray energies. ARPES images with energy resolution up to a few tens of meV are typically acquired on the time scale of minutes. A few application examples illustrate the power of our advanced soft‐X‐ray ARPES instrumentation to explore the electronic structure of bulk crystals with resolution in three‐dimensional momentum, access buried heterostructures and study elemental composition of the valence states using resonant excitation. 相似文献
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We study the expectation value of the phase of the fermion determinant for Wilson lattice fermions with chemical potential. We use quenched SU(3) ensembles and implement a recently proposed exact dimensional reduction of the fermion determinant. Ensembles at several temperatures below and above the phase transition are studied and we analyze the role of the quark mass, the temperature, the volume and the topological sectors. We compare our numerical results to predictions from chiral perturbation theory. 相似文献
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Baumberger F Hengsberger M Muntwiler M Shi M Krempasky J Patthey L Osterwalder J Greber T 《Physical review letters》2004,92(19):196805
The character of the surface state wave function on regularly stepped Cu(111) is reinvestigated. It is shown that the qualitative change at terrace lengths around 17 A observed previously by Ortega et al. [Phys. Rev. Lett. 84, 6110 (2000)]] must necessarily be described as a change from a propagating superlattice state to a terrace-confined quasi-one-dimensional state. This reconciles previous, apparently contradictory experimental results and sheds new light on the behavior of nearly free electrons in nanostructures. Possible mechanisms driving the localization are discussed on the basis of the surface state bulk penetration depth, which has been measured in both regimes. 相似文献
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Borisenko SV Kordyuk AA Koitzsch A Fink J Geck J Zabolotnyy V Knupfer M Büchner B Berger H Falub M Shi M Krempasky J Patthey L 《Physical review letters》2006,96(6):067001
We report the observation of a novel effect in the bilayer Pb-Bi2Sr2CaCu2O8 (Pb-Bi2212) high-T(c) superconductor by means of angle-resolved photoemission with circularly polarized excitation. Different scattering rates, determined as a function of energy separately for the bonding and antibonding copper-oxygen bands, strongly imply that the dominating scattering channel is odd with respect to layer exchange within a bilayer. This is inconsistent with a phonon-mediated scattering and favors the participation of the odd collective spin excitations in the scattering mechanism in near-nodal regions of the k space, suggesting a magnetic nature of the pairing mediator. 相似文献
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Baumberger F Hengsberger M Muntwiler M Shi M Krempasky J Patthey L Osterwalder J Greber T 《Physical review letters》2004,92(1):016803
The interaction of the Shockley surface state with the step lattice of vicinal Cu(111) leads to the formation of an electronic superlattice state. On Cu(443), where the average terrace length forms a "shape resonance" with the Fermi wavelength, we find a step-lattice-induced band-gap opening at the Fermi level. A gap magnitude >200 meV is inferred from high resolution photoemission experiments and line shape analysis. The corresponding energy gain with respect to a gapless case is approximately 11 meV/unit cell, and is a substantial contribution to the stabilization of the step lattice. 相似文献