Towards an integrated biosensor array for simultaneous and rapid multi-analysis of endocrine disrupting chemicals

In this paper we propose the construction and application of a portable multi-purpose biosensor array for the simultaneous detection of a wide range of endocrine disruptor chemicals (EDCs), based on the recognition operated by various enzymes and microorganisms. The developed biosensor combines both electrochemical and optical transduction systems, in order to increase the number of chemical species which can be monitored. Considering to the maximum residue level (MRL) of contaminants established by the European Commission, the biosensor system was able to detect most of the chemicals analysed with very high sensitivity. In particular, atrazine and diuron were detected with a limit of detection of 0.5 nM, with an RSD% less than 5%; paraoxon and chlorpyrifos were revealed with a detection of 5 μM and 4.5 μM, respectively, with an RSD% less than 6%; catechol and bisphenol A were identified with a limit of detection of 1 μM and 35 μM respectively, with an RSD% less than 5%.     

N‐arylamides and N‐arylcarbamates N?CO internal rotation barrier study by molecular modeling

Amides and carbamates present an energetic barrier associated to N? C(O) bond rotation, which determines two different equilibrium geometries. In this work, the conformational equilibrium of formanilide, acetanilide, methyl and t‐butyl phenylcarbamates, and their N‐methylderivatives was studied by AM1 and B3LYP/6‐31G(d,p) calculations. The effect of aryl p‐substituents (MeO, Me, Cl, Br, CN, and NO₂) was also studied. Amide barriers were found by DFT calculation between 12 and 21 kcal/mol. Carbamates, on the other hand, showed barriers between 11 and 15 kcal/mol. AM1 underestimates the energetic barriers and provides values around half those obtained by B3LYP/6‐31G(d,p) calculations. Electron withdrawing substituents on aryl group decrease the barrier. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

On a discrete-time model with replicator dynamics in renewable resource exploitation

We consider a discrete-time version of the model proposed by Lamantia and Radi [15 F. Lamantia, and D. Radi, Exploitation of renewable resources with differentiated technologies: an evolutionary analysis, Math. Comput. Simulation 108 (2015), pp. 155–174. doi:10.1016/j.matcom.2013.09.013.[Crossref], [Web of Science ®] , [Google Scholar]] to describe a fishery where a population regulated by a logistic growth function is exploited by a pool of agents that can choose, at each time period, between two different harvesting strategies according to a profit-driven evolutionary selection rule. The resulting discrete dynamical system, represented by a two-dimensional nonlinear map, is characterized by the presence of invariant lines on which the dynamics are governed by one-dimensional restrictions that represent pure, i.e. adopted by all players, strategies. However, interesting dynamics related to interior attractors, where players playing both strategies coexist, are evidenced by analytical as well as numerical methods that reveal local and global bifurcations.     

Correlation of financial markets in times of crisis

Using the eigenvalues and eigenvectors of correlations matrices of some of the main financial market indices in the world, we show that high volatility of markets is directly linked with strong correlations between them. This means that markets tend to behave as one during great crashes. In order to do so, we investigate financial market crises that occurred in the years 1987 (Black Monday), 1998 (Russian crisis), 2001 (Burst of the dot-com bubble and September 11), and 2008 (Subprime Mortgage Crisis), which mark some of the largest downturns of financial markets in the last three decades.     

Temperature-programmed desorption of methylnaphthalene from alkali-metal faujasites

Interaction between 1-methylnaphthalene and alkali-metal X and Y zeolites has been investigated using TPD. All spectra show only a single peak, the temperature of which changes with the nature and amount of the alkali-metal cation and the Si/Al ratio of the faujasite. A correlation between peak temperature and average charge of structural oxygen atoms of the zeolite is shown. On the basis of the atomic charge distribution in the 1-methylnaphthalene molecule, it is, suggested that adsorption is initiated by interaction between the alkali-metal cation and the carbon atom of the methyl group. Simultaneously, an interaction involving hydrogens atoms of the aromatic rings and structural oxygen atoms of the zeolite occurs, except for X samples containing high amounts of large alkali-metal cations.     

ACID-base properties of a CERIA-lanthana catalytic system

A ceria-lanthana system was prepared by the sol-gel technique in order to obtain active catalysts for the 4-methylpentan-2-ol conversion. As the products distribution strongly depends on the acid-base features of the catalyst, acidity and basicity of the CeO₂-La₂O₃ samples were determined by adsorption microcalorimetry, using ammonia and carbon dioxide as probe molecules. Both concentration and strength of the sites were assessed and their nature was investigated by analysing the microcalorimetric data in the light of the structural and textural characterisation previously carried out. Present samples are compared to a formerly investigated ceria-lanthana system prepared by a different procedure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Calorimetric study of molecular interactions in mixtures of substances containing carbonyl and dialkylamino groups

A Tian-Calvet type calorimeter has been used to determine molar excess enthalpies at 298.15 K as a function of concentration for mixtures ofN,N-dialkylated aminoketones or amides+n-heptane. These data are examined on the basis of a quasi-chemical theory using group-surface interactions. The occurrence of the hetero-proximity effect between -CO- and-N < groups is suggested by the variation of the interchange parameters.

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Zusammenfassung Ein Kalorimeter vom Tian-Calvet-Typ wurde zur Bestimmung der molaren Überschußenthalpie von Mischungen vonn-Heptan mitN,N-dialkylierten Aminoketonen bzw. Amiden bei 298.15 K in Abhängigkeit von der Konzentration verwendet. Die erhaltenen Daten wurden nach der quasi-chemischen Theorie unter Verwendung von Wechselwirkungen zwischen Gruppen und Überfläche ausgewertet. Das Auftreten des hetero-proximity-Effektes zwischen-CO- und -N <-Gruppen wird durch Veränderung der Austauschparameter angezeigt.

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- 298.15 N,N- -. - , . -- -N < .

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This is evidence indeed that proton acceptors, such as tertiary amines, shift the ketoenol equilibrium towards the formation of enols [3].