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41.
Ramírez CL Pegoraro C Trupp L Bruttomesso A Amorebieta V Vera DM Parise AR 《Physical chemistry chemical physics : PCCP》2011,13(45):20076-20080
Two triarylamine centers bridged through an aliphatic bridge feature unexpected charge transfer properties, bearing an important electronic coupling between them in the absence of a π linker; EPR, electrochemistry, electronic spectroscopy and first principles molecular calculations are combined to study the electronic structure of this compound. 相似文献
42.
Leandro Chaves Rêgo Andrea Maria dos Santos 《European Journal of Operational Research》2019,272(2):587-594
We generalize a network formation model for co-authorship introducing the possibility of the connections having different link strengths. Different link strengths represent the fact that authors may put different efforts into different collaborations. To evaluate the model, we consider the notions of efficiency and pairwise stability, which are based on a utility function that measures the benefits for an author to belonging to a certain network structure. We divide the analysis in two cases, considering that link strengths are unbounded or bounded. In the first case, we show that if there are more than two authors in the network, then there is no pairwise stable network. In the second case, we show that the pairwise stable networks consist of completely connected disjoint components where essentially all link strengths are maximal. Regarding efficiency, in both cases, if the number of authors is even, then the unique efficient network structure consists of pairs of connected authors. 相似文献
43.
João Paulo dos Santos Benedito Leandro 《Journal of Mathematical Analysis and Applications》2019,469(2):882-896
We consider the static vacuum Einstein spacetime when the spatial factor is conformal to a n-dimensional pseudo-Euclidean space. The most general ansatz that reduces the resulting system of partial differential equations to a system of ordinary differential equations is completely described. We obtain the entire set of solutions of the reduced system, where the classical Schwarzschild solution arises as a particular solution. In addition, we show that the Riemannian spatial factors associated to these solutions are foliated by parallel hypersurfaces of constant mean curvature. 相似文献
44.
45.
1-Substituted isatins are transformed into indole derivatives by means of ethyl chloroacetate. In fact, under the conditions of the Darzens reaction they give two glycidic ester isomers 4 and 5 which, by hydrolysis in alkaline medium, undergo a transposition to indole-2,3-dicarboxylic acids 2 together with minor amounts of indole-3-carboxylic acids 3 . From isatin itself, 2,3-dicarboxyindole-1-acetic acid ( 6 ) was obtained. 相似文献
46.
Cavichiolo LJ Hasegawa T Nunes FS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(1):161-165
Herein we report the synthetic route and detailed characterization of the macrocyclic complex [Co(dohpn)(SCN)2] and its linkage isomer (dohpn=2,3,9,10-tetramethyl-1,4,8,11-tetraazaundecane-1,3,8,10-tetraen-11-ol-1-olate and py=pyridine) based on analytical, spectroscopic and electrochemical methods. Structural, vibrational and electronic features are discussed and a coherent assignment is proposed on the basis of semi-empirical theoretical calculations. 相似文献
47.
In this article we study the phase transition phenomenon for the Ising model under the action of a non-uniform external magnetic field. We show that the Ising model on the hypercubic lattice with a summable magnetic field has a first-order phase transition and, for any positive (resp. negative) and bounded magnetic field, the model does not present the phase transition phenomenon whenever lim?inf?h i >0, where \(\mathbf{h}=(h_{i})_{i\in \mathbb{Z}^{d}}\) is the external magnetic field. 相似文献
48.
For a topological space X and a point x ∈ X, consider the following game—related to the property of X being countably tight at x. In each inning n ∈ ω, the first player chooses a set A n that clusters at x, and then the second player picks a point a n ∈ A n ; the second player is the winner if and only if \(x \in \overline {\left\{ {{a_n}:n \in \omega } \right\}} \).In this work, we study variations of this game in which the second player is allowed to choose finitely many points per inning rather than one, but in which the number of points they are allowed to choose in each inning has been fixed in advance. Surprisingly, if the number of points allowed per inning is the same throughout the play, then all of the games obtained in this fashion are distinct. We also show that a new game is obtained if the number of points the second player is allowed to pick increases at each inning. 相似文献
49.
Paulo Leandro Dattori da Silva 《Annali di Matematica Pura ed Applicata》2010,189(3):403-413
This paper deals with semi-global C k -solvability of complex vector fields of the form ${\mathsf{L}=\partial/\partial t+x^r(a(x)+ib(x))\partial/\partial x,}This paper deals with semi-global C
k
-solvability of complex vector fields of the form L=?/?t+xr(a(x)+ib(x))?/?x,{\mathsf{L}=\partial/\partial t+x^r(a(x)+ib(x))\partial/\partial x,}, r ≥ 1, defined on We=(-e,e)×S1{\Omega_\epsilon=(-\epsilon,\epsilon)\times S^1}, ${\epsilon >0 }${\epsilon >0 }, where a and b are C
∞ real-valued functions in (-e,e){(-\epsilon,\epsilon)}. It is shown that the interplay between the order of vanishing of the functions a and b at x = 0 influences the C
k
-solvability at Σ = {0} × S
1. When r = 1, it is permitted that the functions a and b of L{\mathsf L}depend on the x and t variables, that is, L=?/?t+x(a(x,t)+ib(x,t))?/?x,{\mathsf{L}=\partial/\partial t+x(a(x,t)+ib(x,t))\partial/\partial x,}where (x, t) ? We{(x, t)\in\Omega_\epsilon}. 相似文献
50.
Federico Holik César Massri A. Plastino Leandro Zuberman 《International Journal of Theoretical Physics》2013,52(6):1836-1876
Let $\mathcal{C}$ be the set of all possible quantum states. We study the convex subsets of $\mathcal{C}$ with attention focused on the lattice theoretical structure of these convex subsets and, as a result, find a framework capable of unifying several aspects of quantum mechanics, including entanglement and Jaynes’ Max-Ent principle. We also encounter links with entanglement witnesses, which leads to a new separability criteria expressed in lattice language. We also provide an extension of a separability criteria based on convex polytopes to the infinite dimensional case and show that it reveals interesting facets concerning the geometrical structure of the convex subsets. It is seen that the above mentioned framework is also capable of generalization to any statistical theory via the so-called convex operational models’ approach. In particular, we show how to extend the geometrical structure underlying entanglement to any statistical model, an extension which may be useful for studying correlations in different generalizations of quantum mechanics. 相似文献