Two-player simultaneous location game: Preferential rights and overbidding

Competitive location problems can be characterized by the fact that the decisions made by others will affect our own payoffs. In this paper, we address a discrete competitive location game in which two decision-makers have to decide simultaneously where to locate their services without knowing the decisions of one another. This problem arises in a franchising environment in which the decision-makers are the franchisees and the franchiser defines the potential sites for locating services and the rules of the game. At most one service can be located at each site, and one of the franchisees has preferential rights over the other. This means that if both franchisees are interested in opening the service in the same site, only the one that has preferential rights will open it. We consider that both franchisees have budget constraints, but the franchisee without preferential rights is allowed to show interest in more sites than the ones she can afford. We are interested in studying the influence of the existence of preferential rights and overbidding on the outcomes for both franchisees and franchiser. A model is presented and an algorithmic approach is developed for the calculation of Nash equilibria. Several computational experiments are defined and their results are analysed, showing that preferential rights give its holder a relative advantage over the other competitor. The possibility of overbidding seems to be advantageous for the franchiser, as well as the inclusion of some level of asymmetry between the two decision-makers.     

A New Ent-Kaurane from the Roots of Lasianthaea aurea

Chemistry of Natural Compounds - A known kaurenoic acid (1), together with a new kaurane derivative named 3α-isobutyryloxykaurenoic acid (2), was isolated from the roots of Lasianthaea aurea,...     

Thermogravimetric studies on catalytic effect of metal oxide nanoparticles on asphaltene pyrolysis under inert conditions

This study investigated the catalytic effect of NiO, Co₃O₄ and Fe₃O₄ nanoparticles toward asphaltene thermal decomposition (pyrolysis) under inert conditions. Asphaltene adsorbed onto the selected nanoparticles were subjected to thermal decomposition up to 800?°C in a thermogravimetric analyzer. The presence of nanoparticles caused a significant decrease in the asphaltene decomposition temperature and activation energy. Activation energies for the process were calculated using the Ozawa?CFlynn?CWall method. All the selected metal oxide nanoparticles showed high catalytic activity toward asphaltene decomposition in the following order NiO?>?Co₃O₄?>?Fe₃O₄. This study confirms that metal oxide nanoparticles can significantly enhance the thermal decomposition of heavy hydrocarbons, like asphaltenes.     

Hybrid EuIII Coordination Luminophore Standing on Two Legs on Silica Nanoparticles for Enhanced Luminescence

In this study, we have demonstrated a two-legged, upright molecular design method for monochromatic and bright red luminescent Ln^III-silica nanomaterials. A novel Eu^III-silica hybrid nanoparticle was developed by using a doubly binding TPPO−Si(OEt)₃ (TPPO: triphenyl phosphine oxide) linker. The TPPO−Si(OEt)₃ was confirmed by ¹H, ³¹P, ²⁹Si NMR spectroscopy and single-crystal X-ray analysis. Luminescent Eu(hfa)₃ and Eu(tfc)₃ moieties (hfa: hexafluoroacetylacetonate, tfc: 3-(trifluoromethylhydroxymethylene)camphorate) were fixed onto TPPO−Si(OEt)₃-modified silica nanoparticles, producing Eu(hfa)₃(TPPO−Si)₂-SiO₂ and Eu(tfc)₃(TPPO−Si)₂-SiO₂, respectively. Eu(hfa)₃(TPPO−Si)₂−SiO₂ exhibited the higher intrinsic luminescence quantum yield (93 %) and longer emission lifetime (0.98 ms), which is much larger than those of previously reported Eu^III-based hybrid materials. Eu(tfc)₃(TPPO−Si)₂−SiO₂ showed an extra-large intrinsic emission quantum yield (54 %), although the emission quantum yield for the precursor Eu(tfc)₃(TPPO−Si(OEt)₃)₂ was found to be 39 %. These results confirmed that the TPPO−Si(OEt)₃ linker is a promising candidate for development of Eu^III-based luminescent materials.     

Study of benznidazole–cyclodextrin inclusion complexes, cytotoxicity and trypanocidal activity

The current chemotherapy for Chagas disease is still based on benznidazole, which has low solubility, but complexation with cyclodextrins provides a way of increasing the solubility. The objective of this work was to characterize the inclusion complexes formed between benznidazole (BNZ) and randomly 2-methyled-β-cyclodextrin (RM-β-CD) in aqueous solution and study cytotoxicity and trypanocidal. BNZ:RM-β-CD solution complex systems were prepared and characterized using the phase solubility diagram, nuclear magnetic resonance and a photostability assays, also to investigate the in vitro trypanocidal activity with epimastigote forms of Trypanossoma cruzi and the study of cytotoxicity against mammal cells. The phase-solubility diagram displayed an A _L-type feature, providing evidence of the formation of soluble inclusion complexes. The continuous variation method showed the existence of a complex with 1:1 stoichiometry. Toxicity assays demonstrated that inclusion complexes were able to reduce the toxic effects caused by benznidazole alone and that this did not interfere with the trypanocidal activity of the benznidazole. The use of inclusion complexes benznidazole:cyclodextrin is thus a promising alternative for the development of a safe and stable liquid formulation and a new option for the treatment of Chagas disease.     

Determination of Sulfaguanidine in Food and Veterinary Pharmaceuticals by Flow Injection Analysis with Spectrophotometric Detection

This work proposes a flow injection analysis system for sulfaguanidine determination in pharmaceutical and food samples. The method was based on the reaction of sulfaguanidine with nitronium ion to produce a colored complex whose absorbance was measured at 545?nm. The flow injection analysis system’s significant parameters were checked by a fractional factorial design 2^7–2 and optimization by a Doehlert matrix. The flow injection analysis system shows optimum values at 0.28, 2.00, and 0.11% (w/v) for N-naphtil ethylenediamine, ammonium sulfamate, and sodium nitrite concentrations, respectively. The possible interferents present in pharmaceutical and food samples were assessed by a multivariate technique and depicted on probability charts, indicating no significant interferences at the 95% level of confidence interval. The method showed detection and quantification limits of 0.012 and 0.039?mg?L^?1, an analytical frequency of 30 readings h^?1 and precision always lower than 5.0% expressed as the relative standard deviation. The obtained results were in accordance with those obtained by high-performance liquid chromatography.