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91.
Jasquer A. Sehnem Priscila Milani Vanessa Nascimento Leandro H. Andrade Luciano Dorneles Antonio L. Braga 《Tetrahedron: Asymmetry》2010,21(8):997-1003
N-Trifluoracyl β-chalcogeno amides and N-perfluoracyl β-thio amide ligands were prepared by a simple and efficient reaction sequence. These new ligands were evaluated in palladium-catalyzed alkylation of rac-(E)-1,3-diphenyl-2-propenyl acetate in the presence of dimethyl malonate and an enantioselectivity of up to 99% was obtained. After catalysis, the fluorous ligand can be easily recovered by liquid–liquid extraction and reused without loss in the activity. 相似文献
92.
93.
Robust branch-cut-and-price for the Capacitated Minimum Spanning Tree problem over a large extended formulation 总被引:1,自引:0,他引:1
Eduardo Uchoa Ricardo Fukasawa Jens Lysgaard Artur Pessoa Marcus Poggi de Aragão Diogo Andrade 《Mathematical Programming》2008,112(2):443-472
This paper presents a robust branch-cut-and-price algorithm for the Capacitated Minimum Spanning Tree Problem (CMST). The
variables are associated to q-arbs, a structure that arises from a relaxation of the capacitated prize-collecting arborescence problem in order to make
it solvable in pseudo-polynomial time. Traditional inequalities over the arc formulation, like Capacity Cuts, are also used.
Moreover, a novel feature is introduced in such kind of algorithms: powerful new cuts expressed over a very large set of variables
are added, without increasing the complexity of the pricing subproblem or the size of the LPs that are actually solved. Computational
results on benchmark instances from the OR-Library show very significant improvements over previous algorithms. Several open
instances could be solved to optimality. 相似文献
94.
Liliana Costa C.M. da Fonseca Enide Andrade Martins 《Linear algebra and its applications》2008,428(7):1524-1537
In this work we give an interpretation of vertices and edges of the acyclic Birkhoff polytope, Tn=Ωn(T), where T is a tree with n vertices, in terms of graph theory. We generalize a recent result relatively to the diameter of the graph G(Tn). 相似文献
95.
We propose a structural credit risk model for consumer lending using option theory and the concept of the value of the consumer’s reputation. Using Brazilian empirical data and a credit bureau score as proxy for creditworthiness we compare a number of alternative models before suggesting one that leads to a simple analytical solution for the probability of default. We apply the proposed model to portfolios of consumer loans introducing a factor to account for the mean influence of systemic economic factors on individuals. This results in a hybrid structural-reduced-form model. And comparisons are made with the Basel II approach. Our conclusions partially support that approach for modelling the credit risk of portfolios of retail credit. 相似文献
96.
C.R. Mendonça U.M. Neves L. De Boni A.A. Andrade D.S. dos Santos Jr. F.J. Pavinatto S.C. Zilio L. Misoguti O.N. Oliveira Jr. 《Optics Communications》2007,273(2):435-440
In this paper we present optical anisotropy induced by 150-fs laser pulses operating at 775 nm in poly(methyl methacrylate) (PMMA) films doped with Disperse Red 13 (DR13). Two-photon absorption of DR13 induces reversible birefringence in the sample, a feature associated with the molecular orientation caused by isomerization of the azochromophores. No irreversible anisotropy, associated with photobleaching of the chromophore was observed. The slope of 2 obtained for the induced birefringence as a function of the excitation irradiance corroborates the two-photon nature of the process. 相似文献
97.
98.
99.
María Cuartero Jonathan Sabaté del Río Pascal Blondeau Joaquín A. Ortuño F. Xavier Rius Francisco J. Andrade 《Analytica chimica acta》2014
The development of a solid-contact potentiometric sensor based on conducting rubbers using a carbon nanotubes ink is described here. Commercial rubbers are turned into conductive ones by a simple and versatile method, i.e. painting an aqueous dispersion of single-walled carbon nanotubes on the polymer surface. On this substrate, both the working ion-selective electrode and the reference electrode are built in order to form an integrated potentiometric cell. As a proof-of-principle, selective potassium electrodes are fully characterized giving comparable performances to conventional electrodes (sensitivity, selectivity, stability, linear range, limit of detection and reproducibility). As an application of the rubber-based electrodes, a bracelet was constructed to measure potassium levels in artificial sweat. Since rubbers are ubiquitous in our quotidian life, this approach offers great promise for the generation of chemical information through daily objects. 相似文献
100.
Andrade CA de Oliveira HP Oliveira MD Correia MT Coelho LC de Melo CP 《Colloids and surfaces. B, Biointerfaces》2011,88(1):100-107
This work is dedicated to the investigation of the prevailing molecular interactions between Cratylia mollis (Cramoll) and Concanavalin A (Con A) lectins and ionic (sodium dodecylsulfate, SDS) and non-ionic (Triton X-100, TX-100) surfactants, where we have used electrical impedance spectroscopy to map the dielectric characteristics of mixed lectin/surfactant solutions. The disorder induced in the lectin conformation is proportional to the extent of the access of the surfactant to the fluorophore present in the protein, resulting in its progressive unfolding. The complete unfolding of the lectin is associated to the formation of micelles in the core of the protein, each one of them containing a large number of detergent molecules, and therefore the process can be accompanied by measuring the electrical response of the binary surfactant/lectin system. For instance, the change in the real part of the impedance as a function of the relative concentration of the surfactant in the binary solution exhibits a breaking in its linear behavior that can be taken as indicative of a qualitative change in the environment surrounding the protein residue. We consider these results strong evidence in favor of using impedance spectroscopy methods for the analysis of protein-surfactant associations and for the characterization of the interactions that must prevail when the protein unfolds as the relative surfactant concentration is increased in aqueous solutions of these binary systems. 相似文献