Abstract:Turing patterns in the chlorine dioxide-iodine-malonic acid reaction were modified through additions of sodium halide salt solutions. The range of wavelengths obtained is several times larger than in the previously reported literature. Pattern wavelength was observed to significantly increase with sodium bromide or sodium chloride. A transition to a uniform state was found at high halide concentrations. The observed experimental results are qualitatively well reproduced in numerical simulations with the Lengye… Show more
“…At this point, we are ready to test the recently published method of adding halide ions to the CDIMA system to increase the wavelength of the Turing patterns. 20 Although, it was originally used to modify patterns in a one-side-fed open reactor, we found that it can be applied in closed two-layer systems as well. We have chosen Br – ions, which were added to the ClO 2 -free initial side to avoid the oxidation of Br – by ClO 2 during the soaking of the gel pieces.…”
Reaction–diffusion
waves and stationary Turing patterns
are observed in closed two-layer gel reactors, where the two compartments
are initially filled with complementary sets of reactants of the chlorine
dioxide–iodine–malonic acid–poly(vinyl alcohol)
reaction. The asymmetrical loading generates concentration gradients
and the patterns form at the interface between the two parts. These
easy-to-perform experiments allow us to study a wide range of dynamical
phenomena without requiring a specific reactor design or the use of
sophisticated equipment. To get complementary information on pattern
formation in parallel and perpendicular to the direction of the concentration
gradients, two geometrically different configurations of compartments
are presented. We demonstrate that three variants of the initial distribution
of the chemicals can be equally applied, and this flexibility provides
a way to introduce additional reagents to perturb the dynamics of
the systems. A noticeable increase in the wavelength of Turing patterns
and in the period of waves has been induced by adding bromide ions.
The interaction of Turing and Hopf modes has been observed as a result
of not only the variation of the initial poly(vinyl alcohol) concentration
but that of the gradients as well.
“…At this point, we are ready to test the recently published method of adding halide ions to the CDIMA system to increase the wavelength of the Turing patterns. 20 Although, it was originally used to modify patterns in a one-side-fed open reactor, we found that it can be applied in closed two-layer systems as well. We have chosen Br – ions, which were added to the ClO 2 -free initial side to avoid the oxidation of Br – by ClO 2 during the soaking of the gel pieces.…”
Reaction–diffusion
waves and stationary Turing patterns
are observed in closed two-layer gel reactors, where the two compartments
are initially filled with complementary sets of reactants of the chlorine
dioxide–iodine–malonic acid–poly(vinyl alcohol)
reaction. The asymmetrical loading generates concentration gradients
and the patterns form at the interface between the two parts. These
easy-to-perform experiments allow us to study a wide range of dynamical
phenomena without requiring a specific reactor design or the use of
sophisticated equipment. To get complementary information on pattern
formation in parallel and perpendicular to the direction of the concentration
gradients, two geometrically different configurations of compartments
are presented. We demonstrate that three variants of the initial distribution
of the chemicals can be equally applied, and this flexibility provides
a way to introduce additional reagents to perturb the dynamics of
the systems. A noticeable increase in the wavelength of Turing patterns
and in the period of waves has been induced by adding bromide ions.
The interaction of Turing and Hopf modes has been observed as a result
of not only the variation of the initial poly(vinyl alcohol) concentration
but that of the gradients as well.
“…Numerical simulations of equations (2.1)–(2.2) show very good agreement with experiments, as shown in figure 2. The LE model has also been modified to account for a variety of external factors, such as competitive binding interactions to the immobile substrate [41] or photoinhibition [42,43]. Figure 2Comparison of labyrinthine Turing patterns in ( a ) the CDIMA reaction–diffusion system and ( b ) the LE model.…”
Section: Early Chemical Turing Patternsmentioning
confidence: 99%
“…Many recent studies of chemical Turing patterns use the CDIMA reaction in a CFUR, where the patterns form in a quasi-two-dimensional gel with one-sided feeding [14,41,45,46]. A schematic for the experimental setup is shown in [14].…”
Section: The Chlorine Dioxide-iodine-malonic Acid Reactionmentioning
confidence: 99%
“…A Fourier spectrum of an image of the Turing pattern can be used to calculate the pattern wavelength. A description of the wavelength analysis method used for CDIMA Turing patterns can be found in [41].…”
Section: The Chlorine Dioxide-iodine-malonic Acid Reactionmentioning
confidence: 99%
“…In general, the wavelength of Turing patterns generated by the CDIMA reaction varies inversely with the chlorine dioxide concentration [45,51] and is typically on the order of several hundred micrometres. Gaskins et al [41] showed that other chemical species added to the system can strongly influence the pattern wavelength. In particular, they hypothesized that adding other halide anions (Cl− and Br−) may change the pattern wavelength through a competing reaction that forms trihalide complexes rather than triiodide complexes—which then occupy some sites on the relatively-immobile (PVA) substrate.…”
Section: The Chlorine Dioxide-iodine-malonic Acid Reactionmentioning
In 1952, Alan Turing proposed a theory showing how morphogenesis could occur from a simple two morphogen reaction–diffusion system [Turing, A. M. (1952)
Phil. Trans. R. Soc. Lond.
A
237
, 37–72. (doi:10.1098/rstb.1952.0012)]. While the model is simple, it has found diverse applications in fields such as biology, ecology, behavioural science, mathematics and chemistry. Chemistry in particular has made significant contributions to the study of Turing-type morphogenesis, providing multiple reproducible experimental methods to both predict and study new behaviours and dynamics generated in reaction–diffusion systems. In this review, we highlight the historical role chemistry has played in the study of the Turing mechanism, summarize the numerous insights chemical systems have yielded into both the dynamics and the morphological behaviour of Turing patterns, and suggest future directions for chemical studies into Turing-type morphogenesis.
This article is part of the theme issue ‘Recent progress and open frontiers in Turing’s theory of morphogenesis’.
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