Transitions to Electrochemical Turbulence

Varela, Hamilton; Beta, Carsten; Bonnefont, Antoine; Krischer, Katharina

doi:10.1103/physrevlett.94.174104

Cited by 59 publications

(53 citation statements)

References 22 publications

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“…In this case, the applied current reflects the electron flow through the solid/liquid interface and is a measure of the departure from equilibrium in the system, similarly to the potential difference across the solid/liquid interface under potentiostatic control. 38,39 A general overview of the oscillatory dynamics is given in Figure 3 in terms of the potential oscillations obtained during a galvanodynamic sweep (dI/dt ) 5 µA s -1 ) at different temperatures. Potential oscillations are born at low current values via a subcritical Hopf bifurcation and disappear at high current values through a saddle-loop bifurcation, where the limit cycle collides with the fixed point in the oxygen evolution branch, similar to the behavior observed for related systems.…”

Section: Resultsmentioning

confidence: 99%

Temperature (Over)Compensation in an Oscillatory Surface Reaction

et al. 2008

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Biological rhythms are regulated by homeostatic mechanisms that assure that physiological clocks function reliably independent of temperature changes in the environment. Temperature compensation, the independence of the oscillatory period on temperature, is known to play a central role in many biological rhythms, but it is rather rare in chemical oscillators. We study the influence of temperature on the oscillatory dynamics during the catalytic oxidation of formic acid on a polycrystalline platinum electrode. The experiments are performed at five temperatures from 5 to 25°C, and the oscillations are studied under galvanostatic control. Under oscillatory conditions, only non-Arrhenius behavior is observed. Overcompensation with temperature coefficient (q 10 , defined as the ratio between the rate constants at temperature T + 10°C and at T) < 1 is found in most cases, except that temperature compensation with q 10 ≈ 1 predominates at high applied currents. The behavior of the period and the amplitude result from a complex interplay between temperature and applied current or, equivalently, the distance from thermodynamic equilibrium. High, positive apparent activation energies were obtained under voltammetric, nonoscillatory conditions, which implies that the non-Arrhenius behavior observed under oscillatory conditions results from the interplay among reaction steps rather than from a weak temperature dependence of the individual steps.

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Section: Resultsmentioning

confidence: 99%

Temperature (Over)Compensation in an Oscillatory Surface Reaction

et al. 2008

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“…Uma grande motivação para tais estudos reside na utilização de análogos químicos como modelos funcionais 5 no estudo de padrões de atividade em sistemas biológi-cos, obviamente, bem mais complexos e menos tratáveis 6 . Exemplos de sistemas físico-químicos, cujas propriedades emergentes vêm sendo estudadas recentemente incluem processos heterogêne-os nas interfaces sólido/gás [7][8][9] e sólido/líquido [10][11][12] , assim como reações homogêneas como no caso dos osciladores da família do bromato [13][14][15][16] .…”

Section: Propriedades Emergentes E Sistemas Complexosunclassified

“…Pode-se afirmar o efeito de iluminação tem sido pouquíssimo explorado nesse sistema até então 25,26 . Tais investigações assumem importância vital tendo em vista que estudos sobre a formação e manipulação de padrões espaço-temporais na presença de diferentes tipos de acoplamentos espaciais é considerada atualmente uma das áreas mais ativas de pesquisa no ramo de auto-organização dinâmica 11,12,27 . /acetona/Mn(II)-ferroína operado em regime de batelada.…”

Section: A Reação De Belousov-zhabotinskyunclassified

Dinâmica complexa no sistema bromato/hipofosfito/acetona/manganês e ferroína

Tokoro¹,

Oliveira²,

Varela³

2007

Quím. Nova

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Recebido em 19/12/06; aceito em 10/4/07; publicado na web em 25/10/07 COMPLEX DYNAMICS IN THE BROMATE/HYPOPHOSPHITE/ACETONE/MANGANESE AND FERROIN SYSTEM. New chemical systems have been recently designed for the study of complex phenomena such as oscillatory dynamics in the temporal domain and spatiotemporal pattern formation. Systems derived from oscillators based on the chemistry of bromate are the most extensively studied, with the celebrated Belousov-Zhabotinsky (BZ) reaction being the most popular example. Problems such as the formation of bubbles (CO 2 ) and solid precipitate in the course of the reaction and the occurrence of simply short-lived oscillations under batch conditions are very common and, in some cases, compromise the use of some of these systems. It is investigated in this paper the dynamic behavior of the bromate/hypophosphite/acetone/dual catalyst system, which has been sugested as an interesting alternative to circumvent those inconvenients. In this work, manganese and ferroin are employed as catalysts and the complete system (BrO 3 -/H 2 PO 2 -/acetone/Mn(II)-ferroin) is studied under batch conditions. Temporal symmetry breaking was studied in a reactor under agitation by means of simultaneous records of the potential changes of platinum and Ag/AgBr electrodes, both measured versus a reversible hydrogen electrode. Additionally, spatio-temporal formation of target patterns and spiral waves were obtained when the oscillating mixture was placed in a quasi two-dimensional reactor.Keywords: oscillations; chemical kinetics; pattern formation. INTRODUÇÃO Propriedades emergentes e sistemas complexosDefine-se formalmente comportamento emergente como "comportamento coletivo de um agregado de subunidades fisicamente similares não observado individualmente por nenhuma sub-unidade" 1 . Em um contexto mais amplo, Korn 2 compilou as principais definições de propriedades emergentes como sendo dadas em termos: da não aditividade das suas partes; de uma novidade, algo simplesmente novo; da não dedutibilidade e, da não preditabilidade. Finalmente, o autor 2 encerra que emergência é a nova associação que conduz a novas e estáveis configurações observáveis. Emergência é a propriedade mais importante dos sistemas complexos. O comportamento de um sistema complexo não pode ser entendido em termos apenas da extrapolação das propriedades dos seus componentes individuais, ou seja, as propriedades que surgem no nível macroscópico não podem ser preditas a partir das propriedades dos componentes microscópicos, como apresentado no artigo clássico More is different 3 .Whitesides e Ismagilov 4 classificaram um sistema complexo como um sistema no qual: sua evolução é muito sensível às condições iniciais ou a pequenas perturbações; o número de componentes independentes interagindo é grande ou, um no qual há vários caminhos através dos quais a evolução do sistema pode proceder. Comportamento complexo expresso na forma de cinética oscilatória e estruturação espacial, por exemplo, é comum em muitos sistemas reacionais mantidos...

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“…More formally, Zoldi and Greenside [35,36,37,38] suggested using PCA for determining the number of degrees of freedom in spatially extended systems by considering the minimum number of principal components required to describe a fraction f (0<f<1) of a multivariate record. Let i 2 , i=1,…,N, again be the non-negative eigenvalues of the associated correlation matrix S given in descending order.…”

Section: Kld Dimension Densitymentioning

confidence: 99%

Complexity Concepts and Non-Integer Dimensions in Climate and Paleoclimate Research

Donner¹

2012

Fractal Analysis and Chaos in Geosciences

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Transitions to Electrochemical Turbulence

Cited by 59 publications

References 22 publications

Temperature (Over)Compensation in an Oscillatory Surface Reaction

Temperature (Over)Compensation in an Oscillatory Surface Reaction

Dinâmica complexa no sistema bromato/hipofosfito/acetona/manganês e ferroína

Complexity Concepts and Non-Integer Dimensions in Climate and Paleoclimate Research

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