Synthesis of indoles by intermolecular cyclization of unfunctionalized nitroarenes and alkynes, catalyzed by palladium-phenanthroline complexes

Palladium-phenanthroline complexes efficiently catalyze the reaction of nitroarenes with arylalkynes and CO to give 3-arylindoles by an ortho-C-H functionalization of the nitroarene ring. Both electron-withdrawing and electron-donating substituents are tolerated on the nitroarene, except for bromide and activated chloride. Nitroarenes bearing electron-withdrawing substituents react faster, but the selectivity of the reaction depends on both polar and radical stabilization effects. Among those tested, only arylalkynes afforded indoles under the investigated conditions. The reaction mechanism was partly investigated. The kinetics is first order in nitroarene concentration and the rate-determining step of the cycle is the initial nitroarene reduction. No primary isotope effect is observed on either rate or selectivity, implying that the cyclization step is fast.     

Functional EEG connectivity during competition

Background

Social behavior and interactions pervasively shape and influence our lives and relationships. Competition, in particular, has become a core topic in social neuroscience since it stresses the relevance and salience of social comparison processes between the inter-agents that are involved in a common task. The majority of studies, however, investigated such kind of social interaction via one-person individual paradigms, thus not taking into account relevant information concerning interdependent participants’ behavioral and neural responses. In the present study, dyads of volunteers participated in a hyperscanning paradigm and competed in a computerized attention task while their electrophysiological (EEG) activity and performance were monitored and recorded. Behavioral data and inter-brain coupling measures based on EEG frequency data were then computed and compared across different experimental conditions: a control condition (individual task, t0), a first competitive condition (pre-feedback condition, t1), and a second competitive condition following a positive reinforcing feedback (post-feedback condition, t2).

Results

Results showed that during competitive tasks participants’ performance was improved with respect to control condition (reduced response times and error rates), with a further specific improvement after receiving a reinforcing feedback. Concurrently, we observed a reduction of inter-brain functional connectivity (primarily involving bilateral prefrontal areas) for slower EEG frequency bands (delta and theta). Finally, correlation analyses highlighted a significant association between cognitive performance and inter-brain connectivity measures.

Conclusions

The present results may help identifying specific patterns of behavioral and inter-brain coupling measures associated to competition and processing of social reinforcements.

     

Characterization of the surface interacting ability of carbon black by means of electron paramagnetic resonance analysis of adsorbed Cu2+, supported by surface analysis and atomic absorption

Electron paramagnetic resonance (EPR) has been used to investigate the adsorption capability and the surface interacting ability towards Cu(II) solutions (CuCl2, Cu(NO3)2, CuSO4 in water or ethanol) of various carbon blacks, both graphitized and ungraphitized, selected on the basis of the surface area, namely, Carbograph1 (area = 100 m2/g), Carbograph4 (area = 210 m2/g), and Carbograph5 (area = 560 m2/g), which were indicated as C1g, C4g, C5g (g = graphitized), and C1ng, C4ng, C5ng (ng = ungraphitized). The EPR analysis was supported by surface analysis, for evaluating the surface area, the pore volume and the porosity, and by atomic absorption to obtain the adsorbed Cu(II) amounts. Graphitization provokes a decrease in surface area, but C1g, at low surface area, showed a unexpected increase of the adsorption ability ascribed to the formation of new surface porosity closed by graphite layers. The carbon samples showed a broad unresolved EPR signal due to mobile unpaired electrons in the carbon matrix. Graphitized samples presented a narrower signal than ungraphitized samples, which increases in width with the increase in surface area (with the exception of C5ng due to the high exposition of the wide surface to oxydizing external agents) and upon prolonged thermal treatment. The signal intensity of the carbon paramagnetic centers decreases upon Cu(II) adsorption. Computer aided analysis of the EPR spectra of the solids after Cu(II) adsorption allowed to extract structural information on the Cu-surface site complexes. The Cu2+ ions coordinated with surface polar sites, mainly oxygenated. Adsorption depends on the different Cu(II) salts, caused by the salt solubility and the interacting ability of the counter-ion. In several cases the solutions concentrated in the carbon porosity leading to precipitation of the salt. Ethanol solutions are more adsorbed at the carbon surface than water solutions; Cu(II) partially retains its solvation shell and partially presents electron transfer to the carbon surface. Adsorption is favored to ungraphitized carbons with respect to the graphitized ones due to both the higher surface area, and the higher hydrophilicity of the surface. In summary, these carbon powders, widely used for chromatographic applications, show an adsorption capability towards Cu(II) solutions higher than expected due to both a definite porosity, and the presence of polar groups which are not eliminated with chemical surface treatments.     

Structure-Directing Agents for the Synthesis of TiO(2) -Based Drug-Delivery Systems

A series of titanium oxides was prepared by using a surfactant-template method (STM) and used as a carrier for the sustained release of ibuprofen, which was chosen as a model drug. This STM provides an efficient route to TiO(2) matrices with both high surface area (when compared with those that were obtained by using traditional synthetic approaches) and well-defined mesoporous textures. Some parameters of the synthetic procedure were varied: pH value, surfactant, and thermal treatment. The physicochemical nature of the surface carriers were investigated by means of N(2) -physisorption measurements and FTIR spectroscopy. The effect of the amount of drug on the release kinetics was also investigated. The drug delivery was evaluated in vitro in four different physiological solutions (that simulated the gastrointestinal tract) to analyze the behavior of the TiO(2) -based systems if they were to be formulated as oral DDSs. Our optimized approach is a good alternative to the classical methods that are used to prepare efficient TiO(2) -based drug-delivery systems.     

Molecular dynamics reveal that isoDGR-containing cyclopeptides are true αvβ3 antagonists unable to promote integrin allostery and activation

Ain't got that swing(-out): The cyclopeptide isoDGR is emerging as a new αvβ3 integrin binding motif. Agreement between the results of computational and biochemical studies reveals that isoDGR-containing cyclopeptides are true αvβ3 integrin antagonists that block αvβ3 in its inactive conformation (see scheme). isoDGR-based ligands may give αvβ3 antagonists without paradoxical effects.     

About the OH yield in the radiolysis of an aqueous/H2O2 system. Its optimisation for water treatment

Unless the radiolytic reducing species are neutralised or converted into oxidising species, an EB remediation system cannot be considered a true Advanced Oxidation Processes (AOP). A water/H₂O₂ system irradiated by UVC mercury lamps constitutes a widely used OH production method. Employing H₂O₂ in radiolysis as well, an enhancement of the oxidative efficiency of an EB treatment can be obtained. Pulse radiolysis measurements of an aerated aqueous/H₂O₂/KSCN system have been systematically undertaken to assess the optimal H₂O₂ concentration. By linearly fitting a competition kinetics relationship, it is found that the scavengeable extra-yield of OH is ΔG(OH)=0.24 μmol J^?1 (R=0,9958), while the maximum experimental yield is measured G(OH)_max=(0.52±0.02) μmol J^?1 when [H₂O₂]=5–10 mM. Exceeding these concentrations the OH yield drops off.     

Long time asymptotics of a Brownian particle coupled with a random environment with non-diffusive feedback force

We study the long time behavior of a Brownian particle moving in an anomalously diffusing field, the evolution of which depends on the particle position. We prove that the process describing the asymptotic behavior of the Brownian particle has bounded (in time) variance when the particle interacts with a subdiffusive field; when the interaction is with a superdiffusive field the variance of the limiting process grows in time as t^2γ−1, 1/2<γ<1. Two different kinds of superdiffusing (random) environments are considered: one is described through the use of the fractional Laplacian; the other via the Riemann-Liouville fractional integral. The subdiffusive field is modeled through the Riemann-Liouville fractional derivative.     

Weibel-induced filamentation during an ultrafast laser-driven plasma expansion

The development of current instabilities behind the front of a cylindrically expanding plasma has been investigated experimentally via proton probing techniques. A multitude of tubelike filamentary structures is observed to form behind the front of a plasma created by irradiating solid-density wire targets with a high-intensity (I ~ 10(19) W/cm(2)), picosecond-duration laser pulse. These filaments exhibit a remarkable degree of stability, persisting for several tens of picoseconds, and appear to be magnetized over a filament length corresponding to several filament radii. Particle-in-cell simulations indicate that their formation can be attributed to a Weibel instability driven by a thermal anisotropy of the electron population. We suggest that these results may have implications in astrophysical scenarios, particularly concerning the problem of the generation of strong, spatially extended and sustained magnetic fields in astrophysical jets.     

Structure‐Directing Agents for the Synthesis of TiO2‐Based Drug‐Delivery Systems

A series of titanium oxides was prepared by using a surfactant‐template method (STM) and used as a carrier for the sustained release of ibuprofen, which was chosen as a model drug. This STM provides an efficient route to TiO₂ matrices with both high surface area (when compared with those that were obtained by using traditional synthetic approaches) and well‐defined mesoporous textures. Some parameters of the synthetic procedure were varied: pH value, surfactant, and thermal treatment. The physicochemical nature of the surface carriers were investigated by means of N₂‐physisorption measurements and FTIR spectroscopy. The effect of the amount of drug on the release kinetics was also investigated. The drug delivery was evaluated in vitro in four different physiological solutions (that simulated the gastrointestinal tract) to analyze the behavior of the TiO₂‐based systems if they were to be formulated as oral DDSs. Our optimized approach is a good alternative to the classical methods that are used to prepare efficient TiO₂‐based drug‐delivery systems.     

Balanced metrics on Cartan and Cartan–Hartogs domains

This paper consists of two results dealing with balanced metrics (in Donaldson terminology) on noncompact complex manifolds. In the first one we describe all balanced metrics on Cartan domains. In the second one we show that the only Cartan–Hartogs domain which admits a balanced metric is the complex hyperbolic space. By combining these results with those obtained in Loi and Zedda (Mathematische Annalen, 2011, to appear) we also provide the first example of complete, Kähler-Einstein and projectively induced metric g such that α g is not balanced for all α > 0.