Belousov-Zhabotinsky Oscillator Research Articles

Growing Polymer Vesicles Generated by Polymerization Induced Self-Assembly Coupled With a Living Chemical Reactor

Chemical oscillatory reactions have attracted intensive attention due to their autonomous, continuous, and periodic features. Herein, the radicals generated in Belousov-Zhabotinsky (BZ) oscillator was used to initiate RAFT (reversible addition-fragmentation chain transfer) polymerization of 2-methoxyethyl acrylate (MEA) extending from hydrophilic poly(ethylene glycol) chain transfer agent (PEG-CTA) to give amphiphilic block copolymer, which self-assembled into collective objects with a size ranging from sub-micron to micron. Small-to-giant polymer vesicles could be generated using the above-mentioned BZ-PISA technology, the encapsulation of active BZ recipe into the vesicles also endorses the vesicles with growing features with potential for drug delivery and biomedical applications.

Visual chemo-chronometric assay for quantifying ethanol in alcoholic drinks by the colorimetric Belousov-Zhabotinsky oscillator

A simple chemo-chronometric method utilizing the Belousov-Zhabotinsky (BZ) oscillating reaction for the efficient detection of ethanol in alcoholic beverages has been developed. This visual detecting strategy only required a smartphone, without implemented instrumental detection systems, to video a unique colorimetric alternating (red-to-blue) feature of the BZ solution system containing 0.50 M bromate, 0.12 M malonic acid, 0.03 M bromide, 0.10 M sulfuric acid, and 0.2 mM ferroin under the perturbation of ethanol. The RGB intensity signals, termed the colorimetric oscillating signals (COS), could be drawn from recorded files through the image processing. We found from the COS characteristics that the oscillation period was inversely proportional to the ethanol levels as a consequence of its reaction with bromate in the studied system. Based on the established calibration, the ethanol content was effectively evaluated with good precision (<2.8% RSD). Also, the assay was successful with 5% error for the quantification of ethanol in commercial drink samples, signifying its accuracy and potential applicability.

Identification of Two Hetero-Substituent-Aromatic Isomers of - 4- and 7-Hydroxy Coumarin with the Belousov-Zhabotinsky Oscillator

Identification of Two Hetero-Substituent-Aromatic Isomers of - 4- and 7-Hydroxy Coumarin with the Belousov-Zhabotinsky Oscillator

"Cognitive" modes in small networks of almost identical chemical oscillators with pulsatile inhibitory coupling.

The Lavrova-Vanag (LV) model of the periodical Belousov-Zhabotinsky (BZ) reaction has been investigated at pulsed self-perturbations, when a sharp spike of the BZ reaction induces a short inhibitory pulse that perturbs the BZ reaction after some time τ since each spike. The dynamics of this BZ system is strongly dependent on the amplitude Cinh of the perturbing pulses. At Cinh > Ccr, a new pseudo-steady state (SS) emerges far away from the limit cycle of the unperturbed BZ oscillator. The perturbed BZ system spends rather long time in the vicinity of this pseudo-SS, which serves as a trap for phase trajectories. As a result, the dynamics of the BZ system changes qualitatively. We observe new modes with packed spikes separated by either long "silent" dynamics or small-amplitude oscillations around pseudo-SS, depending on Cinh. Networks of two or three LV-BZ oscillators with strong pulsatile coupling and self-inhibition are able to generate so-called "cognitive" modes, which are very sensitive to small changes in Cinh. We demonstrate how the coupling between the BZ oscillators in these networks should be organized to find "cognitive" modes.

Kinetics of the Acetaminophen-Based Oscillatory Chemical Reaction with and without Ferroin as Catalyst: An Inorganic Prototype Model for Acetaminophen–Ethanol Syndrome

This paper describes the nonlinear behaviour of the acetaminophen-based uncatalysed Belousov–Zhabotinsky oscillator and its dynamics in the presence of ferroin as catalyst. The role of free metal ions as catalysts was examined and the results compared with those of corresponding complexed catalysts. Free metal ions were found to be sluggish with respect to the evolution of the oscillatory regime as compared to complexed ones. The effect was monitored of change of the ligand moiety of the catalyst complex on the oscillatory parameters. Since ethanol potentiates the hepatotoxicity caused by acetaminophen in vivo, it is thought to understand this interaction by virtue of causing perturbation of the acetaminophen-based oscillator with different concentrations of ethanol with and without ferroin as catalyst. Another dimension to the ethanol effect was examined by perturbation of the system with ethanol at different stages of the reaction so as to get an idea as to whether it is acetaminophen or some reactive intermediate generated in the reaction system which reacts with ethanol. Further, the ferroin-catalysed oscillator is taken as a prototype inorganic model of the acetaminophen–ethanol syndrome, as ferroin and hypobromous acid (HOBr) act as inorganic replacements for cytochrome P450 and nicotinamide adenine dinucleotide phosphate (NADPH) in alcohol metabolism.

Lyapunov exponents and the Belousov-Zhabotinsky oscillator: an interactive computational approach

The Belousov-Zhabotinsky (BZ) chemical oscillator is the most studied oscillator. It has been modelled on the basis of single-step mechanisms which have been continuously refined since the seminal manuscript by Field, Koros and Noyes in 1972. This manuscript reports on a unique way of modelling the global dynamics of the oscillator by assuming that the BZ oscillator has shown chaotic behaviour. The unique mathematical definition of chaos is very stringent, and, in this manuscript, we attempt to trace this unique exotic behaviour by the use of ‘onto’ maps of the interval onto itself which are known to exhaustively show a universal sequence of states that has all the hallmarks of chaotic behaviour. A series of one-humped maps of the interval display, through iterations and subsequent symbolic dynamics, a universal sequence of steps that commence with period-doubling, culminating in chaotic behaviour at some accumulation point of an appropriate bifurcation parameter.We put this theory to the test for the BZ oscillator in this manuscript by selecting a unique continuous map of the interval. This was then decomposed by an iterative treatment. Metric entropy and subsequent arbiter of chaotic behaviour was determined by evaluation of Lyapunov exponents which were then compared to observed BZ oscillator states. Our proposed map satisfactorily modelled the global dynamics of the BZ oscillator; predicted period-doubling, and a regime after a critical bifurcation parameter, where chaotic sequences were dense.We also produce, in the Addendum, an iterative MatLab procedure that any reader can utilize to reveal the type of states and behaviour reported here.

Spatially Localized Chemical Patterns around an A + B → Oscillator Front.

When two gels, each loaded with a different set of reactants A and B of an oscillatory reaction, are brought into contact, reaction-diffusion patterns such as waves or Turing patterns can develop in the reactive contact zone. The initial condition which separates the reactants at the beginning leads to a localization in space of the different dynamical regimes accessible to the chemical oscillator. We study here both numerically and experimentally the composite traveling structures resulting from the interaction between chemical fronts and localized waves in the case in which the reactants of such an A + B → oscillator system are those of the canonical Belousov-Zhabotinsky (BZ) oscillating reaction. A transition between different dynamics is obtained by varying the initial concentration of the organic substrate of the BZ reactants, which is one of the parameters controlling the local excitability. We show that the dynamical regime (excitable or oscillatory) characterizing the BZ oscillator in the initial contact area is the key feature which determines the spatiotemporal evolution of the system. The experimental results are in qualitative agreement with the theoretical predictions.

Controlled polymerization of acrylonitrile proceeded along with the Belousov–Zhabotinsky oscillator by changing its stirring conditions

Chemical oscillations of the manganese-ion catalyzed Belousov–Zhabotinsky (BZ) reaction system were found to be controlled by changing its stirring conditions. The oscillation stopped at a high stirring rate, while it reappeared immediately by reducing the stirring rate. It is known in the BZ reaction system, that the radical polymerization takes place along with the oscillation when acrylic monomers are added. By the addition of acrylonitrile to the system stirred at a high stirring rate, the oscillation as well as the polymerization of acrylonitrile stopped. The radical polymerization of acrylonitrile by the BZ oscillator is thus found to be made controllable by changing the mixing conditions.

Experimental, numerical, and mechanistic analysis of the nonmonotonic relationship between oscillatory frequency and photointensity for the photosensitive Belousov-Zhabotinsky oscillator.

The oscillation frequency of a nonlinear reaction system acts as a key factor for interaction and superposition of spatiotemporal patterns. To control and design spatiotemporal patterns in oscillatory media, it is important to establish the dominant frequency-related mechanism and the effects of external forces and species concentrations on oscillatory frequency. In the Ru(bipy)3(2+)-catalyzed Belousov-Zhabotinsky oscillator, a nonmonotonic relationship exists between light intensity and oscillatory frequency (I-F relationship), which is composed of fast photopromotion and slow photoinhibition regions in the oscillation frequency curve. In this work, we identify the essential mechanistic step of the I-F relationship: the previously proposed photoreaction Ru(II)* + Ru(II) + BrO3(-) + 3H(+) → HBrO2 + 2Ru(III) + H2O, which has both effects of frequency-shortening and frequency-lengthening. The concentrations of species can shift the light intensity that produces the maximum frequency, which we simulate and explain with a mechanistic model. This result will benefit studies of pattern formation and biomimetic movement of oscillating polymer gels.

A Novel Mechanism for in Situ Nucleation of Spirals Controlled by the Interplay between Phase Fronts and Reaction–Diffusion Waves in an Oscillatory Medium

Understanding the transition from planar fronts, trigger waves, or solitary waves 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 introduce a new mechanism for the formation of rotating spiral waves based on the collision between a phase reduction front and trigger waves propagating in the oscillatory Belousov–Zhabotinsky (BZ) medium. The phase reduction front is triggered by imposing a heterogeneous spatial gradient of a chemical agent S able to temporarily sequester an inhibitory species of the oscillatory mechanism. This determines an initial oxidized transient over the whole reactor and, successively, a phase desynchronization by which the system recovers the excitable condition. The resulting reduction front can induce and control the transition from phase to trigger waves, whose properties depend upon the concentration profile of S along the spatial coordinate. By means of a numerical approach, we show that smooth gradients of the species S favor the formation of stacking waves with short characteristic wavelengths and the adaptation of the velocity of this cluster of pulses to that of the leading reduction front. Front-back annihilation between the reduction front and an incoming pulse may occur when the concentration profile of S has a steep gradient along the spatial domain. Experimental evidence of this mechanism as a possible source for spiral formation is shown in a quasi-two-dimensional geometry by using the BZ oscillator including the zwitterionic surfactant tetradecyl dimethylammonium oxide (C14DMAO). By segregating the inhibitor Br2, the micelles cause the onset of an oxidized induction period which vanishes after a few minutes through the propagation of a reduction phase front originated from an anisotropic spatial distribution of the surfactant C14DMAO. The reduction front gives a complex interplay with following target waves, including front–back collision. The spontaneous break of symmetry from target to spirals is controlled here by tuning the concentration of the surfactant or the alternative inhibitor species Br–.

Butterfly effect in a chemical oscillator

The strong sensitivity of aperiodic dynamics to initial conditions is one of the fingerprinting features of chaotic systems. While this dependence can be directly verified by means of numerical approaches, it is quite elusive and difficult to be isolated in real experimental systems. In this paper, we discuss a didactic and self-consistent method to show the divergent behaviour between two infinitesimally different solutions of the famous Belousov–Zhabotinsky oscillator simultaneously undergoing a transition to a chaotic regime. Experimental data are also used to give an intuitive visualization of the essential meaning of a Lyapunov exponent, which allows for a more quantitative characterization of the chaotic transient.

The Effect of Sodium Dodecylbenzenesulfonate (SDBS) Micelles on a BelousovZhabotinsky Oscillating System Catalyzed with a Tetraazamacrocyclic Copper(II) Complex

AbstractThis article deals with the influence of micelles of the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) on the BelousovZhabotinsky (BZ) oscillating reaction catalyzed by a tetraazamacrocyclic copper(II) complex [CuL](ClO4)2, an enzyme‐like catalyst (L=5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene). Unlike the classical BZ oscillator in which malonic acid is usually used as a substrate, malic acid (an intermediate in the Krebs cycle) is involved in this oscillating system. Experiments reveal that formation of the SDBS micelles markedly affects the behavior of the oscillating reaction. It is found that there is a linear relationship between the change in the oscillation amplitude (ΔA) and the concentration of SDBS, whereas the change in the oscillation period (ΔT) is linearly proportional to the SDBS concentration. The most likely mechanism that involves the formation of the SDBS micelles and the effects of the micelles on the oscillating chemical system can be rationalized by assuming that the SDBS micelles are so negatively charged that they attract more [CuL]3+ than [CuL]2+. This hypothesis was confirmed by UV/VIS spectrophotometric measurements of a constant concentration of [CuL](ClO4)2 in different concentrations of SDBS; as the SDBS concentration increased, the absorbance of [CuL](ClO4)2 increased, while the maximum absorption wavelength for [CuL](ClO4)2 remained at 502 nm.

Large enhancement of oscillating chemiluminescence with [Ru(bpy)3]2+-catalyzed Belousov-Zhabotinsky reaction in the presence of tri-n-propylamine

Oscillating chemiluminescence enhanced by the addition of tri-n-propylamine (TPrA) to the typical Belousov-Zhabotinsky (BZ) reaction system catalyzed by ruthenium(II)tris(2.2'-bipyridine)(Ru(bpy)3 (2+) ) was investigated using a luminometry method. The [Ru(bpy)3 ](2+) /TPrA system was first used as the catalyst for a BZ oscillator in a closed system, which exhibited a shorter induction period, higher amplitude and much more stable chemiluminescence (CL) oscillation. The effects of various concentrations of TPrA, oxygen and nitrogen flow rate on the oscillating behavior of this system were examined. In addition, the CL intensity of the [Ru(bpy)3 ](2+) /TPrA-BZ system was found to be inhibited by phenol, thus providing a way for use of the BZ system in the determination of phenolic compounds. Moreover, the possible mechanism of the oscillating CL reaction catalyzed by [Ru(bpy)3 ](2+) /TPrA and the inhibition effects of oxygen and phenol on this oscillating CL system were considered.

Role of the reagents consumption in the chaotic dynamics of the Belousov–Zhabotinsky 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-convection model to explore the influence of the reagents consumption (BrO in particular) in the inverse transition from chaos to periodicity. We demonstrated that, on the route towards thermodynamic equilibrium, the reagents concentration directly modulates the strength of the coupling between chemical kinetics and mass transport phenomena. An effective sequential decoupling (reaction-diffusion-convection --> reaction-diffusion --> reaction) takes place upon the reagents consumption and this is at the basis of the transition from chaos to periodicity.

Reaction Routes Leading to CO2 and CO in the Briggs−Rauscher Oscillator: Analogies between the Oscillatory BR and BZ Reactions

With Fenton-type experiments, it is shown that the intense CO2/CO evolution in the Briggs-Rauscher (BR) reaction is due to decarboxylation/decarbonylation of organic free radicals. The metal ion applied in the Fenton-type experiments was Fe2+ or Ti3+ or Mn2+ combined with H2O2 or S2O(8)(2-) as a peroxide, whereas the organic substrate was malonic acid (MA) or a 1:1 mixture of MA and iodomalonic acid (IMA). Experiments with a complete BR system applying MA or the MA/IMA mixture indicate that practically all CO2 and CO comes from IMA. The decarboxylation/decarbonylation mechanisms of various iodomalonyl radicals can be analogous to that of the bromomalonyl radicals studied already in the Belousov-Zhabotinsky (BZ) reaction. It is found that an intense CO2/CO evolution requires the simultaneous presence of H2O2, IO3-, Mn2+, and IMA. It is suggested that the critical first step of this complex reaction takes place in the coordination sphere of Mn2+. That first step can initiate a chain reaction where organic and hydroperoxyl radicals are the chain carriers. A chain reaction was already found in a BZ oscillator as well. Therefore, the analogies between the BR and BZ oscillators are due to the fact that in both mechanisms, free radicals and, in most cases, also transition-metal complexes play an important role.

Mechanistic Investigations of the BZ Reaction with Oxalic Acid Substrate. I. The Oscillatory Parameter Region and Rate Constants Measured for the Reactions of HOBr, HBrO2, and Acidic BrO3- with Oxalic Acid

This paper is the first part of a study reinvestigating the mechanism of the Belousov−Zhabotinsky (BZ) reaction of oxalic acid, which is the simplest organic substrate for a BZ oscillator. New experiments are performed to find the oscillatory region in 1 M sulfuric acid at 20 °C. The removal rate of the end product bromine by an inert gas stream is a critical parameter here: oscillations can be observed only in a window of that parameter. The “rate constant” for the physical removal of bromine is measured as a function of the gas flow rate and reactor volume; furthermore, the rate constants of three component reactions important in this system are also determined. These are oxygen atom transfer reactions to the oxalic acid substrate from Br(I) (hypobromous acid), from Br(III) (bromous acid), and from Br(V) (acidic bromate) compounds. In these second-order reactions, the partial order of each oxybromine species is 1. The measured rate constants are kI = 17 ± 2 M-1 s-1, kIII = 4.2 ± 0.5 M-1 s-1, and kV = (...

Chaos in a Simulated Belousov-Zhabotinsky Reaction

Proceeding from an eleven-step reaction scheme, complex dynamic behaviour has been simulated for a Belousov–Zhabotinsky oscillator, in particular a transition from steady state to quasiperiodic and bursting oscillations, and futher on to regular relaxation oscillation via a complicated sequence of alternating periodic and chaotic regimes.

Identification of reaction products and stoichiometry of the overall process in the methylmalonic acid Belousov-Zhabotinsky oscillator. A proton NMR study

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIdentification of reaction products and stoichiometry of the overall process in the methylmalonic acid Belousov-Zhabotinsky oscillator. A proton NMR studyEddy W. Hansen, Hans C. Gran, and Peter RuoffCite this: J. Phys. Chem. 1985, 89, 4, 682–684Publication Date (Print):February 1, 1985Publication History Published online1 May 2002Published inissue 1 February 1985https://doi.org/10.1021/j100250a025RIGHTS & PERMISSIONSArticle Views111Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (369 KB) Get e-Alerts