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排序方式: 共有513条查询结果,搜索用时 546 毫秒
191.
Aldona Kostuch Iwona A. Rutkowska Beata Dembinska Anna Wadas Enrico Negro Keti Vezz Vito Di Noto Pawel J. Kulesza 《Molecules (Basel, Switzerland)》2021,26(17)
Platinum is a main catalyst for the electroreduction of oxygen, a reaction of primary importance to the technology of low-temperature fuel cells. Due to the high cost of platinum, there is a need to significantly lower its loadings at interfaces. However, then O2-reduction often proceeds at a less positive potential, and produces higher amounts of undesirable H2O2-intermediate. Hybrid supports, which utilize metal oxides (e.g., CeO2, WO3, Ta2O5, Nb2O5, and ZrO2), stabilize Pt and carbon nanostructures and diminish their corrosion while exhibiting high activity toward the four-electron (most efficient) reduction in oxygen. Porosity of carbon supports facilitates dispersion and stability of Pt nanoparticles. Alternatively, the Pt-based bi- and multi-metallic catalysts, including PtM alloys or M-core/Pt-shell nanostructures, where M stands for certain transition metals (e.g., Au, Co, Cu, Ni, and Fe), can be considered. The catalytic efficiency depends on geometric (decrease in Pt–Pt bond distances) and electronic (increase in d-electron vacancy in Pt) factors, in addition to possible metal–support interactions and interfacial structural changes affecting adsorption and activation of O2-molecules. Despite the stabilization of carbons, doping with heteroatoms, such as sulfur, nitrogen, phosphorus, and boron results in the formation of catalytically active centers. Thus, the useful catalysts are likely to be multi-component and multi-functional. 相似文献
192.
Cortellessa Gino Arpino Fausto Dell’Isola Marco Ficco Giorgio Iacomini Luigi Fernicola Vito Bertiglia Fabio 《Journal of Thermal Analysis and Calorimetry》2019,138(4):2901-2912
Journal of Thermal Analysis and Calorimetry - The 2010/31/CE directive has highlighted the necessity to improve the energy efficiency in buildings, since they are responsible for 40% of energy... 相似文献
193.
Patrizia Rogolino Robert Kovács Peter Ván Vito Antonio Cimmelli 《Continuum Mechanics and Thermodynamics》2018,30(6):1245-1258
We derive two different generalized heat-transport equations: the most general one, of the first order in time and second order in space, encompasses some well-known heat equations and describes the hyperbolic regime in the absence of nonlocal effects. Another, less general, of the second order in time and fourth order in space, is able to describe hyperbolic heat conduction also in the presence of nonlocal effects. We investigate the thermodynamic compatibility of both models by applying some generalizations of the classical Liu and Coleman–Noll procedures. In both cases, constitutive equations for the entropy and for the entropy flux are obtained. For the second model, we consider a heat-transport equation which includes nonlocal terms and study the resulting set of balance laws, proving that the corresponding thermal perturbations propagate with finite speed. 相似文献
194.
We propose a model of random diffusion to investigate flow fluctuations in complex networks. We derive an analytical law showing that the dependence of fluctuations with the mean traffic in a network is ruled by the delicate interplay of three factors, respectively, of dynamical, topological and statistical nature. In particular, we demonstrate that the existence of a power-law scaling characterizing the flow fluctuations at every node in the network cannot be claimed. We show the validity of this scaling breakdown under quite general topological and dynamical situations by means of different traffic algorithms and by analyzing real data. 相似文献
195.
Silvia Todros Arturo N. Natali Giuseppe Pace Vito Di Noto 《Journal of Polymer Science.Polymer Physics》2014,52(5):409-418
The effect of steam on chemical structure and mechanical properties of renewable poly(ether‐block‐amide)s (PEBAs) is investigated by different characterization techniques, i.e. FT‐IR, TGA, DSC, DMA, and BES. Steam sterilization is a mandatory process for materials used in medical applications. This process, employed during clinical practice and replicated in this study, affects polymer structure and morphology. Steam induces an increase of polyamide (PA) crystallinity in PEBAs with a majority of PA domains, due to the conformational transition from α‐helix to parallel and anti‐parallel β‐sheet, with stronger hydrogen bonding. In PEBAs with longer polyether (PE) blocks, steam induces an increase of random PA domains and the formation of a more extended hydrogen bonding network between ether and amide moieties of the two segments. As a consequence of these microdomain conformational variations, relevant changes occur in molecular relaxations as demonstrated by DMA and BES results. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 409–418 相似文献
196.
197.
A critical comparison of the application of differential pulse voltammetry and anodic stripping voltammetry to the determination of micro amounts of copper in silicon is described. The anodic stripping technique offers advantages when a dropping mercury capillary with a long drop time is used. The method recommended allows the determination of copper in silicon with a precision of ± 5 %; the limit of determination is about 1μg g-1. Calibration graphs are linear in the range 0–0.2 μg Cu ml-1. Methods for the dissolution of silicon are also compared. 相似文献
198.
Vincenzo Amicarelli Giuseppe Baldassarre Vito Balice Lorenzo Liberti 《Thermochimica Acta》1980,36(2):107-111
A linear correlation between adsorptive affinity and acidic properties of adsorbates is evidenced when phenol. aniline and their o-, m-, and p-nitro-derivatives are adsorbed on granular activated carbon. Thermodesorption energies appear to be empirically related to adsorptivity. 相似文献
199.
We characterize a class of linear spaces by the property that through any point outside two disjoint, but non-parallel lines there is at most one transversal. 相似文献
200.
A differential pulse polarographic method, using the dropping mercury electrode for the determination of the herbicides atrazine, prometrine and simazine is described. The optimum pH is 2. The limit of detection is 8 x 10(-8)M, corresponding to about 15 mu/l. The electrochemical behaviour of the compounds on glassy-carbon and mercury-coated glassy-carbon electrodes was also examined with a view to its use for electrochemical detection of the herbicides after their separation by HPLC. 相似文献