The effect of concentration on the Surface-Enhanced Raman Scattering of p-Aminothiophenol

The organic compound p-aminothiophenol (pATP, HS-Ph-NH2) has become very popular because it is often used for checking the enhancement capability of each new SERS substrate due to its very intense SERS spectra. SERS of pATP on silver electrode is significantly different from its ordinary Raman spectra and it is very dependent on the particular conditions of the SERS experiment. In this work the effect of adsorbate concentration on the potential dependent SERS spectra of pATP recorded on a silver electrode has been studied using NaClO4 as electrolyte. On the other hand, MS-CASPT2 have been performed in order to help the analysis of the experimental results by computing resonance Raman spectra of selected structural models of the metal−adsorbate surface complex. It is found that the spectra are dependent on adsorbate concentration and dominated by a resonant charge transfer (CT) mechanism, where the charge is always transferred from the adsorbate to the metal. The relative SERS enhancements are due to Franck−Condon factors related to the CT process, and there are not intensified bands through Herzberg−Teller contributions. Furthermore, the Raman signals of the SERS recorded at low concentration arise from at least three different molecular species: (i) pATP bonded to silver electrode through sulfur atom (Agn-S−-Ph-NH2); (ii) pATP bonded to silver electrode through both sulfur and nitrogen atoms (Agn-S−-PhNH2-Agm); (iii) The azo derivative p,p′-dimercaptoazobenzene (or its nitrene precursor).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Detection of different species of p-aminothiophenol on silver nanoparticles by Surface-Enhanced Raman Spectroscopy (SERS)

In the present work we have analyzed the experimental and theoretical SERS spectra of the organic compound p-aminothiophenol (pATP, HS-Ph-NH2) recorded on silver nanoparticles. DFT calculations have been performed to support the experimental results in order to estimate the adsorption specie and the corresponding Raman bands assignment. It is found a different adsorption behavior of pATP not only by changing the concentration of the adsorbate but also by exciting the sample at different wavelengths.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Isolation and social instigation in animal models of aggression: effects of an mGLU1 receptor antagonist administration

Isolate-induced aggression in male mice is a model widely used in psychoparmacology of aggression. Animals are usually isolated for 30 days and subsequently treated and confronted with an anosmic opponent in a neutral area. For 10 min, the complete agonistic repertoire exhibited by the experimental animals is examined, allowing a detailed analysis of aggressive behaviors and other exploratory and motor behaviors. We have recently investigated the role of glutamate metabotropic receptors (mGluR) in this experimental model. Glutamate is the major excitatory neurotransmitter in the brain and it acts both at ionotropic (NMDA, AMPA and kainate receptors) and mGluRs, which are members of the G-protein-coupled receptor family. Eight mGluRs have been characterized and grouped into three classes: group I (mGlu1 and 5), group II (mGlu2 and 3) and group III (mGlu4, 6, 7 and 8). We have tested selective ligands available for the subtypes of mGluRs. Group I antagonists were the most effective ones reducing aggression, being especially remarkable the antiaggressive action observed after the administration of JNJ16259685 (an mGlu1 selective antagonist; 0.125-8 mg/kg i.p.), that produced a strong reduction of offensive behaviors (threat and attack), without affecting immobility with all doses. In this context, we wonder whether this drug could also reduce forms of intensified-heightened aggression. In recent years there is an increasing interest in studying excessive-abnormal forms of aggression in rodents, with the aim of providing a higher translational value to the observed violence in humans, in which aggression becomes intense, disproportionate and dysfunctional. We select a social instigation model, where mice are exposed to a brief territory intrusion of an adult male mice physically inaccessible. After this social provocation mice are exposed to a second opponent which now is unprotected. Social instigation dramatically increases aggressive behaviors, which renders this model appropriate for investigating the neurobiological mechanisms of excessive aggressive behavior. Therefore, we implemented a social instigation procedure in the isolation-induced aggression model with a double objective: first, to examine whether “instigation” could increase the aggression obtained by social isolation; and second, to evaluate the antiaggressive effect of an mGlu1 antagonist in heightened aggression. For this purpose, an acute dose of JNJ16259685 (0.5 mg/kg) was administrated to socially instigated animals after isolation, as well as to animals only isolated. Our results revealed that social instigation reduced latency of attack and increased the frequency and duration of attacks against not instigated animals, without affecting motor behaviors. Likewise, JNJ16259685 (0.5 mg/kg) administration significantly reduced aggressive behaviors in both cases. Taken together, this study shows that social instigation is an useful experimental procedure that increases significantly the levels of aggression observed in an isolated-induced aggression model, also demonstrating the involvement of mGlu1 receptors in the modulation of normal and heightened aggression in male mice.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fast and stable contour integration for high order divided differences via elliptic functions

In this paper, we will present a new method for evaluating high order divided differences for certain classes of analytic, possibly, operator valued functions. This is a classical problem in numerical mathematics but also arises in new applications such as, e.g., the use of generalized convolution quadrature to solve retarded potential integral equations. The functions which we will consider are allowed to grow exponentially to the left complex half plane, polynomially to the right half plane and have an oscillatory behaviour with increasing imaginary part. The interpolation points are scattered in a large real interval. Our approach is based on the representation of divided differences as contour integral and we will employ a subtle parameterization of the contour in combination with a quadrature approximation by the trapezoidal rule

Monetary Union, EU financial transfers and regional integration: The Spanish case

According to the best established economic theories, the monetary union does not spontaneously guarantee a catching-up process ("real convergence") among the member states in terms of well-being economic level. On the contrary, the monetary unification can increase the income disparities among countries and regions, if there are not strong compensation policies which help the least developed territorial economies to make an effort of a more intense investment in order to achieve greater production growth rates. Concerning the "real convergence" of the Spanish regions and economy, we must take into account that -according to the new economic theories of the endogenous growth- the infrastructures, the human and technological capital, and other intangible assets require the support of the public investment and the EU budget. This support is particularly important in countries like Spain, where the relative productivity level and the GDP per head are still far below the European average. Therefore, our attention will be focused on three points. In the first place, we are going to analyze the cohesion problem in Spain in the European framework. Secondly, we are going to survey some inconsistencies of the EU budget bearing in mind the real convergence target. And finally, we are going to make some reflections of economic and regional policy taking into account the enlargement of the EU to the east and central European countries in the next future (Agenda 2000).

Hyphessobrycon nicolasi (Teleostei: Characidae) a new species from the Uruguay River basin in the Mesopotamian Region, Argentina

Hyphessobrycon nicolasi is described from the Uruguay River basin in the Mesopotamian Region, Entre Ríos, Argentina. The new species can be distinguished from all congeners by the presence of a well-defined oblique and marginal black stripe on each lobe of the caudal fin. Other characters defining H. nicolasi are the possession of 1-3 teeth with 3-10 cusps on maxilla; outer premaxillary row with 2-3 small teeth, with 5 or 7 cusps; iv-vi, 27-36 anal-fin rays; 33-36 scales on the longitudinal series; two vertical dark spots on the humeral region; dorsal and anal fins dappled in black and base of caudal fin bearing conspicuous black spot; and the presence of bony hooks on the rays of dorsal, anal and caudal fins of the mature males.Fil: Miquelarena, Amalia Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Lopez, Hugo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Lax orthogonal factorisation systems

This paper introduces lax orthogonal algebraic weak factorisation systems on 2-categories and describes a method of constructing them. This method rests in the notion of simple 2-monad, that is a generalisation of the simple reflections studied by Cassidy, H\'ebert and Kelly. Each simple 2-monad on a finitely complete 2-category gives rise to a lax orthogonal algebraic weak factorisation system, and an example of a simple 2-monad is given by completion under a class of colimits. The notions of KZ lifting operation, lax natural lifting operation and lax orthogonality between morphisms are studied.Comment: 59 page

Four-dimensional naturally reductive pseudo-Riemannian spaces

The classification of 4-dimensional naturally reductive pseudo-Riemannian spaces is given. This classification comprises symmetric spaces, the product of 3-dimensional naturally reductive spaces with the real line and new families of indecomposable manifolds which are studied at the end of the article. The oscillator group is also analyzed from the point of view of this classification

MARKET-BASED LAND REFORM AND FARM EFFICIENCY IN COLOMBIA: A DEA APPROACH

This paper uses Data Envelopment Analysis to measure scale and technical efficiencies of 925 farms in rural Colombia and a Tobit model to identify the effects of land market characteristics on efficiency. Findings indicate that although larger farms are more scale efficient, they are not more technical efficient than small farms. Participation in land markets increases technical efficiency, indicating a positive potential role for market-based land reform. Further results show that intensity of violence in rural areas results in increased scale efficiency, allegedly through consolidation of land ownership.Industrial Organization, Productivity Analysis,