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131.
A notion of stability of dynamics under distant perturbations is introduced. It is demonstrated, for quasi-local systems, that the stability of an equilibrium state under the same perturbations implies the state is factorial, i.e. strongly clustering in space. We also characterize the set of perturbations necessary to ensure the equivalence of stability and factorialness. 相似文献
132.
M. C. Apreda F. H. Cano C. Foces-Foces S. Garcia-Blanco 《Journal of chemical crystallography》1981,11(1-2):1-9
Crystals of C20H16N2O2 are orthorombic:P212121,a = 28.1364(21),b = 7.6474(2),c = 7.5376(2) Å,Z = 4, = 6.4 cm–1 (CuK radiation), andM = 316.36. The structure has been solved by direct methods and refined by two-block least-squares toR = R
w = 0.042. The conformation of ringB is a distorted envelope at N(10), and the phenyl rings have acis configuration with respect to the pyridazine ring. Thermal motion of the molecule has been analyzed in terms of the rigid-body TLS model.On leave from Departamento de Fisica, Facultad de Ciencias Exactas, U.N.L.P., calle 115 esq. 49, La Plata, Buenos Aires, Argentina. 相似文献
133.
The stereochemistry of N-bromosuccinimide electrophilic additions to the double bond at the terminal tetrahydropyridazine ring moiety of the 4a,12a-diazatetracyclic compounds 1-4 has been studied. These reactions appear as very regio- and stereoselective. Most the of the results obtained support the hypothesis that the N-bromoamide additions to cyclohexenes and heterocyclic analogous do not occur via the usual AdE2 mechanism, because the nucleophilic step is the rate-limiting one and the main product-determining factor. On the other hand, epoxidation of the double bond in 1-4 and further opening of the oxirane ring take place in accordance with the normal stereochemical rules. 相似文献
134.
L. A. Cano J. F. Bengoa S. J. Stewart R. C. Mercader S. G. Marchetti 《Hyperfine Interactions》2010,195(1-3):93-98
The influence of the impregnation media (ethanol or water) and the calcination atmosphere (air and NO/He) on the hematite nanowires production embedded on a hard template (MCM-41) was studied. The solids were characterized by X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. The results obtained indicate that the more appropriate conditions for the iron oxide nanowires to get inside the MCM-41 hard template seem to be reached using water as a solvent and air as calcination atmosphere. 相似文献
135.
Let G be a discrete subgroup of PU(1,n). Then G acts on ℙℂ
n
preserving the unit ball ℍℂ
n
, where it acts by isometries with respect to the Bergman metric. In this work we look at its action on all of ℙℂ
n
and determine its equicontinuity region Eq(G). This turns out to be the complement of the union of all complex projective hyperplanes in ℙℂ
n
which are tangent to ∂ℍℂ
n
at points in the Chen-Greenberg limit set Λ(G), a closed G-invariant subset of ∂ℍℂ
n
which is minimal for non-elementary groups. We also prove that the action on Eq(G) is discontinuous. Also , if the limit set is “sufficiently general” (i.e. it is not contained in any proper
k
-chain), then each connected component of Eq(G) is a holomorphy domain and it is a complete Kobayashi hyperbolic space. 相似文献
136.
M. Morales Rodriguez A. Díaz Cano T.V. Torchynska G. Polupan S. Ostapenko 《Journal of Non》2008,354(19-25):2272-2275
The paper presents the results of porous SiC study using photoluminescence and scanning electronic microscopy. It is shown that the intensity of defect-related PL bands (2.08, 2.27, 2.44 and 2.63 eV) increases monotonically with the rise of PSiC thickness from 2.1 up to 12.0 μm. These luminescence centers are assigned to surface defects which appear at the PSiC etching process. Photoluminescence intensity stimulation for surface defects is attributed to rise of defect concentrations with increasing of porous layer thickness and to realization of the hot carrier ballistic mechanism at surface defect excitation. Intensity enhancement for exciton-related PL bands (2.79, 2.98 and 3.26 eV ) is attributed to increasing the exciton recombination rate as result of exciton weak confinement in big size SiC NCs of different polytypes (6H–PSiC with inclusions of 15R- and 4H–PSiC). 相似文献
137.
Shallow Flows Over a Permeable Medium: The Hydrodynamics of Submerged Aquatic Canopies 总被引:2,自引:0,他引:2
Aquatic flow over a submerged vegetation canopy is a ubiquitous example of flow adjacent to a permeable medium. Aquatic canopy
flows, however, have two important distinguishing features. Firstly, submerged vegetation typically grows in shallow regions.
Consequently, the roughness sublayer, the region where the drag length scale of the canopy is dynamically important, can often
encompass the entire flow depth. In such shallow flows, vortices generated by the inflectional velocity profile are the dominant
mixing mechanism. Vertical transport across the canopy–water interface occurs over a narrow frequency range centered around
f
v
(the frequency of vortex passage), with the vortices responsible for more than three-quarters of the interfacial flux. Secondly,
submerged canopies are typically flexible, coupling the motion of the fluid and canopy. Importantly, flexible canopies can
exhibit a coherent waving (the monami) in response to vortex passage. This waving reduces canopy drag, allowing greater in-canopy velocities and turbulent stresses.
As a result, the waving of an experimental canopy reduces the canopy residence time by a factor of four. Finally, the length
required for the set-up and full development of mixing-layer-type canopy flow is investigated. This distance, which scales
upon the drag length scale, can be of the same order as the length of the canopy. In several flows adjacent to permeable media
(such as urban canopies and reef systems), patchiness of the medium is common such that the fully developed condition may
not be representative of the flow as a whole.
This paper has previously been published in Transp Porous Med (2009) 78: 309–326; DOI . 相似文献
138.
Alex G. M. Litherland Lee M. Spurway Sergey N. Gordeev Barak D. B. Aaronson Andrew J. Wain Michael A. O’Connell Heidi Piili Mikko Hovilehto Ville-Pekka Matilainen Anne Vuorema Frank Marken 《Journal of Solid State Electrochemistry》2018,22(6):1755-1762
Galvanic exchange involving dissolution of iron and the simultaneous growth of platinum onto 316 L stainless steel was investigated for specimens manufactured by 3D-printing, and the behavior was compared to conventional stainless steel. Novel phenomena associated with the 3D-printed steel, but not conventional steel, reacting in three distinct phases were observed: first, with low platinum loading, a bright etching pattern linked to the laser-manufacturing process is revealed at the steel surface; second, a nanostructured pore pattern with platinum nano-deposits forms; and third, a darker platinum film coating of typically 500-nm thickness forms and then peels off the steel surface with further platinum growth underneath. Unlike the conventional steel (and mainly due to residual porosity), 3D-printed steel supports well-adhered platinum films for potential application in electrocatalysis, as demonstrated for alkaline methanol oxidation. 相似文献
139.
Ruiz E Cirera J Cano J Alvarez S Loose C Kortus J 《Chemical communications (Cambridge, England)》2008,(1):52-54
This theoretical study discusses the interplay of the magnetic anisotropy and magnetic exchange interaction of two Mn6 complexes and suggests that large magnetic anisotropy is not favoured by a high spin state of the ground state. 相似文献