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11.
Recent advances in synthesis and applications of transition metal containing mesoporous molecular sieves 总被引:2,自引:0,他引:2
Work in mesoporous silica-based materials began in the early 1990s with work by Mobil. These materials had pore sizes from 20-500 A and surface areas of up to 1500 m(2) g(-1) and were synthesized by a novel liquid crystal templating approach. Researchers subsequently extended this strategy to the synthesis of mesoporous transition metal oxides, a class of materials useful in catalysis, electronic, and magnetic applications because of variable oxidation states, and populated d-bands-features not found in silicates. These materials are already showing promise in electronic and optical applications hinging on the semiconducting properties of transition metal oxides and their potential to act as electron acceptors, an important feature in the design of cathodic materials. This is the first general review of non-silicate mesoporous materials and will focus on recent advances in this area, emphasizing materials possessing unique electronic, magnetic, or optical properties. Also covered are advances in the synthesis and applications of mesostructured sulfides as well as a new class of template-synthesized platinum-based materials that show promise in heterogeneous catalysis. 相似文献
12.
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
13.
We realized a series of experiments to study the physics of laser–plasma interaction in an intensity regime of interest for the novel “Shock Ignition” approach to Inertial Fusion. Experiments were performed at the Prague Asterix Laser System laser in Prague using two laser beams: an “auxiliary” beam, for pre-plasma creation, with intensity around 7?×?1013?W/cm2 (250?ps, 1ω, λ?=?1315?nm) and the “main” beam, up to 1016?W/cm (250?ps, 3ω, λ?=?438?nm), to launch a shock. The main goal of these experiments is to study the process of the formation of a very strong shock and the influence of hot electrons in the generation of very high pressures. The shock produced by the ablation of the plastic layer is studied by shock breakout chronometry. The generation of hot electrons is analyzed by imaging Kα emission. 相似文献
14.
A new perspective in forest modeling, based on analogies with continuous media physics, is presented. There are two central concepts, one called eco-strain in biomass production, and the other nonlinear allometry. Previously, it was shown that our models, based on works of the pioneers F. Clements and E. Odum, allow exactly 8 types of schemes for succession in dominant/codominant forestry, which conserve nutrients. It is shown that exactly 5 are eco-strained, including competitive, parasitic and mutualistic schemes, whereas 3 are eco-unstrained, and are reversible deformations of the classical straight-line allometries of Huxley. All are cost-preserving over the longer timescale. 相似文献
15.
We elaborate on a recently proposed model of the temporal dependence of polarization mode dispersion in long fiber links. We evaluate the probability that a channel of a wavelength-division multiplexed system never incurs an outage, and the range of frequency over which the parameters that characterize the temporal statistics of the differential group delay are correlated. 相似文献
16.
17.
Michele Antonelli Carolina Vittoria Beccari Giulio Casciola 《Advances in Computational Mathematics》2014,40(4):945-976
In this paper we consider the problem of designing piecewise polynomial local interpolants of non-uniformly spaced data. We provide a constructive approach that, for any assigned degree of polynomial reproduction, continuity order, and support width, allows for generating the fundamental spline functions of minimum degree having the desired properties. Finally, the proposed construction is extended to handle open sets of data and to the case of multiple knots. 相似文献
18.
Peter L. Antonelli Andrej Bna Michael A. Slawi
ski 《Nonlinear Analysis: Real World Applications》2003,4(5):711-722
We prove that, in general, for anisotropic nonuniform continua, seismic rays are geodesics in Finsler geometry. In particular, for separable velocity functions, the geometry is Wagnerian. We provide concrete examples with theoretical discussions and introduce the seismic Finsler metric. 相似文献
19.
By using absorption spectra in a pulsed molecular beam, the rotational temperature and the flow density of the jet are deduced. By using this technique, a comparison between a pulsed and a continuous beam is also reported for NH3, CF2Cl2, and C2H3Cl molecular beams. Moreover, the behaviour of the temperature and density inside the pulsed beam is analyzed as a function of time for pure Ammonia. From these measurements, we deduce that a small improvement is obtained for absorption spectroscopy in the jet by using a pulsed molecular beam. 相似文献
20.
Il Nuovo Cimento D - We have calculated the binding energies of excitons in quantum well structures based on ionic semiconductors by including the electron-hole interactions with the... 相似文献