Stationary Mosaic Patterns and Segmented Waves in a Belousov-Zabotinsky/Sodium Dodecyl Sulfate System.

New Features in the dynamics of a ferroin-catalyzed Belousov-Zhabotinsky reaction induced by a zwitterionic surfactant

Abstract Interactions between reaction–diffusion systems and aggregated host environments are a subject of widespread interest. In this work, the behavior of the Belousov–Zhabotinsky reaction was investigated in a micellar environment formed by the zwitterionic surfactant N-tetradecyl-N,N-dimethylamine oxide (C14DMAO). The appearance of an induction period with a threshold-like dependence upon the surfactant concentration, was detected at [C14DMAO] = 5.0 × 10−3 mol dm−3. These new features were explained in terms of the segregation ability typical of the amphiphilic self-assembling systems. Numerical simulations were also performed to confirm the proposed mechanism.

L’influenza dei siti archeominerari nella geochimica della Toscana meridionale

Passi Verso una Fisica Evolutiva

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…

Isotopic Effect on the Kinetics of the Belousov-Zhabotinsky Reaction

In this work we present results about the deuterium isotope effect on the global kinetics of a Belousov-Zhabotinsky reaction in batch conditions. A nonlinear dependence of the Induction Period upon the percentage of deuterated reactants was found. The isotopic effect on the bromination reaction of malonic acid was evaluated.

Chemical waves and pattern formation in the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/water lamellar system

Origin and extinction of chaotic oscillations in the Belousov-Zhabotinsky reaction

Self organizing reaction-diffusion system in nanostructered matrices.

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

Cross-Diffusionin a Water-in-Oil Microemulsion Loaded with Malonic Acid or Ferroin. Taylor Dispersion Method for Four-Component Systems

Ecological indicators - Entropy

Arsenic Pollution in the Southwest of Tuscany: Monitoring of Cornia Catchment Basin

The territory of Colline Metallifere, in SW Tuscany, is characterized by the presence of strong arsenic anomalies. Some hypotheses, formulated in the last 20 years, based on geological and mineralogical factors have failed to explain the peculiar distribution of this toxic element in soil, fluvial sediments and ground water. Our research group has been studying for four years the problem of arsenic pollution in this district to investigate the origin and the mechanism of As diffusion in the environment. In particular we started a comparative study based on the extensive sampling of the stream sediments of the main waterways of Colline Metallifere (Pecora, Bruna and Cornia and their tributar…

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…

The effect of N-tetradecyl-N,N-dimethylamine oxide micelles on the kinetics of the electron transfer reaction of Ce(IV) with substituted malonic acids

Abstract The kinetics of the oxidation of malonic acid and (its substituted compounds, methyl-, ethyl-, butyl- and benzyl-malonic acid) by ceric ions has been studied at 20.0 °C in the absence and the presence of the surfactant N-tetradecyl-N,N-dimethylamine oxide (C 14 DMAO). The addition of increasing amounts of C 14 DMAO influences the rate of the redox process to an extent that significantly depends on the hydrophobicity of the reducing species. The reactivity data together with the estimated binding constants and the standard transfer free energies of the malonic acids from water to the micelles suggest that the malonic acid is confined to the aqueous pseudo-phase while for the other s…

Isotopic effect on the kinetics of the Belousov-Zhabotinsky reaction: Cerium-Malonic subsystem.

Chemical self-organization in self-assembling biomimetic systems

Abstract Far-from-equillibrium oscillating chemical reactions are among the simplest systems showing complex behaviors and emergent properties. This class of reactions is often employed to mimic and understand the mechanisms of a great variety of biological processes. In this context, pattern formation due to the coupling between reaction and transport phenomena represent an active and promising research area. In this paper, we present results coming from experiments where we tried to blend the structural properties of self-assembled matrixes (sodium dodecyl sulphate micelles and phospholipid bilayers) together with the evolutive peculiarities of the Belousov–Zhabotinsky reaction. A series …

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

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.

Pattern formation in the BZ/C14DMAO zwitterionic micellar system

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…

Influence of ancient mining settlements on Arsenic pollution in the southwest of Tuscany

Inquinamento da arsenico nella Toscana meridionale: studio comparativo tra i fiumi delle Colline Metallifere

Spatio-temporal perturbation of the dynamics of the ferroin catalyzed Belousov-Zhabotinsky reaction in a batch reactor caused by sodium dodecyl sulfate micelles.

The effects of the anionic surfactant sodium dodecyl sulfate (SDS) on the spatio-temporal and temporal dynamics of the ferroin-catalyzed Belousov-Zhabotinsky (BZ) reaction have been studied over a wide surfactant concentration range. For the first time, investigations were performed also for unstirred systems. The presence of SDS in the reaction mixture influences the oscillatory parameters to an extent that significantly depends on the surfactant concentration. The trend of the wave speed v upon the increasing amount of SDS was found to have a maximum at [SDS] = 0.075 mol dm (-3) ( v = 0.071 mm s (-1)), after which the speed decreased to 0.043 mm s (-1) at [SDS] = 0.5 mol dm (-3), which is…

Oscillations, waves and patterns in SDS micellar systems

Chemical Waves and Pattern Formation in the DPPC/Water Lamellar System

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…

Chemical Waves and Pattern Formation in phospholipid/Water Lamellar Systems

The two velocities of technology and nature: A conversation with Adolfo Pèrez Esquivel

Temporal and spatio-temporal behaviour of the BZ reaction in the presence of SDS aggregates

Entropy

Stationary Patterns and Segmented/Big Waves in a Belousov-Zabotinsky/Micelles System

A brief tale on how chemical oscillations became popular an interview with Anatol Zhabotinsky

Effect of the Electrolytes in a closed unstirred Belousov-Zhabotinsky Medium

Arsenic Pollution in the Southwest of Tuscany: Monitoring of Cornia Catchment Basin

Spatial recurrence strategies reveal different routes to Turing pattern formation in chemical systems

We analyze the temporal evolution of hexagonal Turing patterns in two Belousov–Zhabotinsky reactions performed in water-in-oil reverse micro-emulsions under different experimental conditions. The two reactions show different routes to pattern formation through localized spots and through a self replication mechanism. The Generalized Recurrence Plot (GRP) and the Generalized Recurrence Quantification Analysis (GRQA) are used for the investigation of spatial patterns and clearly reveal the different routes leading to the formation of stationary Turing structures.

POLY 496-Behavior of the Belousov-Zhabotinsky oscillator in the presence of carboxymethyl-cellulose

Oscillatory dynamics of the Belousov-Zhabotinsky system in the presence of a self-assembling nonionic polymer. Role of the reactants concentration.

In the present study, the role played by the reactants concentration on the nonlinear response of a Belousov–Zhabotinsky (BZ) system to the addition of a self-assembling non-ionic polymer, poly(ethylene glycol) (PEG), has been assessed. The oscillatory parameters are influenced to an extent that significantly depends on the concentration of both the polymer and the Belousov–Zhabotinsky components. The effects obtained were attributed to the reaction among some of the BZ key species and the backbone and the alcoholic functional groups of the polymer, both in its monomeric and aggregated forms. Support to the proposed perturbation mechanism has been provided by performing numerical simulation…

Ecological indicators – Schrödinger Ratio

Isotopic effect on the kinetics of a closed unstirred Belousov-Zhabotinsky medium