L’influenza dei siti archeominerari nella geochimica della Toscana meridionale

Deuterium isotope effect on the induction period of the cerium catalyzed Belousov-Zhabotinsky reaction

Abstract In this work we present results about the deuterium isotopic effect on the global kinetics of a cerium catalyzed Belousov–Zhabotinsky reaction. A nonlinear dependence of the induction period upon the percentage of deuterated reactants was found in batch conditions. In order to understand this result, we investigated two reaction pathways responsible for the length of the induction period, namely: (a) the reaction between the enolic form of the malonic acid with molecular bromine and (b) the oxidation of malonic acid by the Ce(IV) ion. In both cases we obtained a linear dependence of the kinetic constants on the percentage of deuterated reactants. Nevertheless, by inserting the expe…

An experimental model for mimicking biological systems: the Belousov-Zhabotinsky reaction in Lipid membranes

Chaotic dynamics in an unstirred ferroin catalyzed Belousov–Zhabotinsky reaction

Abstract The Belousov–Zhabotinsky (BZ) reaction is the best known example of far from equilibrium self-organizing chemical reaction. Among the many dynamical behaviors that this reaction can exhibit, spatio-temporal chaos attracted particular interest, both for the ferroin and cerium catalyzed systems. In recent years transient chaos was found in the cerium catalyzed BZ reaction, when conducted in batch and unstirred reactors. It was established that the chaotic oscillations, originated by the coupling among chemical kinetics and transport phenomena, appeared and disappeared following a Ruelle–Takens–Newhouse scenario. In this Letter, we show results about the ferroin catalyzed system condu…

Dynamics of Pattern Formation in Biomimetic Systems

This paper is an attempt to conceptualize pattern formation in self-organizing systems and, in particular, to understand how structures, oscillations or waves arise in a steady and homogenous environment, a phenomenon called symmetry breaking. The route followed to develop these ideas was to couple chemical oscillations produced by Belousov-Zhabotinsky reaction with confined reaction environments, the latter being an essential requirement for any process of Life. Special focus was placed on systems showing organic or lipidic compartments, which represent more reliable biomimetic matrices.

Interplay between the Belousov-Zhabotinsky reaction-diffusion system and biomimetic matrices

Abstract Interactions between reaction–diffusion systems and restricted host environments are a subject of widespread interest. In this work the behaviour of the Belousov–Zhabotinsky reaction was investigated in lamellar phases formed by phospholipid bilayers with relevance for biological systems. The influence of the reactive medium on the structure of the lipid matrix and, in turn, the influence of the matrix on the dynamical evolution of chemical patterns, were studied by small angle scattering.

Control of spontaneous spiral formation in a zwitterionic micellar medium

The transition from planar fronts, trigger waves or solitary pulses to spirals in excitable media, has attracted increasing interest in the past few decades, mainly because of its relevance for biological and medical applications. In this paper we describe a new and convenient method for spiral generation starting from symmetric wavefronts. By using the micelle-forming zwitterionic surfactant N-tetradecyl- N,N-dimethylamine oxide in a Belousov–Zhabotinsky solution, it is possible to control to a large extent the domains where spirals can be spontaneously generated. The mechanism responsible for the wavefront break up lies in the interaction of the propagating waves with the unexcitable regi…

Role of the reagents consumption in the chaotic dynamics of the Belousov-Zhabotitinsky oscillator in closed unstirred reactors

Chemical oscillations generated by the Belousov–Zhabotinsky reaction in batch unstirred reactors, show a characteristic chaotic transient in their dynamical regime, which is generally found between two periodic regions. Chemical chaos starts and finishes by following a direct and an inverse Ruelle–Takens–Newhouse scenario, respectively. In previous works we showed, both experimentally and theoretically, that the complex oscillations are generated by the coupling among the nonlinear kinetics and the transport phenomena, the latter due to concentration and density gradients. In particular, convection was found to play a fundamental role. In this paper, we develop a reaction–diffusion–convecti…