scholarly journals Dynamics of spiral waves and bubble formation in a closed chemical system of thin photosensitive excitable media

2021 ◽  
Vol 2145 (1) ◽  
pp. 012025
Author(s):  
Kritsana Khaothong ◽  
Vikanda Chanchang ◽  
Jarin Kanchanawarin ◽  
Malee Sutthiopad ◽  
Chaiya Luengviriya
Keyword(s):  
Thin Layer ◽  
Bubble Formation ◽  
Three Dimensional ◽  
Spiral Waves ◽  
Excitable Media ◽  
Chemical System ◽  
Layer System ◽  
Cardiac Tissues ◽  
Bz Reaction ◽  
Life Threatening

Abstract Spiral waves have been observed in a thin layer of excitable media. Especially, electrical spiral waves in cardiac tissues connect to cardiac tachycardia and life-threatening fibrillations. The Belousov-Zhabotinsky (BZ) reaction is the most widely used system to study the dynamics of spiral waves in experiments. When the light sensitive Ru(bpy)3 2+ is used as the catalyst, the BZ reaction becomes photosensitive and the excitability of the reaction can be controlled by varying the illumination intensity. However, the typical photosensitive BZ reaction produces many CO2 bubbles so the spiral waves are always studied in thin layer media with opened top surfaces to release the bubbles. In this work, we develop new chemical recipes of the photosensitive BZ reaction which produces less bubbles. To observe the production of bubbles, we investigate the dynamics of spiral waves in a closed thin layer system. The results show that both the speed of spiral waves and the number of bubbles increase with the concentration of sulfuric acid (H2SO4) and sodium bromate (NaBrO3). For high initial concentrations of both reactants, the size of bubbles increases with time until the wave structures are destroyed. We expect that the chemical recipes reported here can be used to study complicated dynamics of three-dimensional spiral waves in thick BZ media where the bubbles cannot escape.

THREE-DIMENSIONAL ASPECTS OF RE-ENTRY IN EXPERIMENTAL AND NUMERICAL MODELS OF VENTRICULAR FIBRILLATION

1999 ◽  
Vol 09 (04) ◽  
pp. 695-704 ◽  
Author(s):  
V. N. BIKTASHEV ◽  
A. V. HOLDEN ◽  
S. F. MIRONOV ◽  
A. M. PERTSOV ◽  
A. V. ZAITSEV
Keyword(s):  
Ventricular Fibrillation ◽  
Numerical Simulations ◽  
Numerical Models ◽  
Three Dimensional ◽  
Spiral Waves ◽  
Excitable Media ◽  
Ventricular Wall ◽  
Two Dimensional ◽  
Key Features ◽  
Scroll Waves

Ventricular fibrillation is believed to be produced by the breakdown of re-entrant propagation waves of excitation into multiple re-entrant sources. These re-entrant waves may be idealized as spiral waves in two-dimensional, and scroll waves in three-dimensional excitable media. Optically monitored, simultaneously recorded endocardial and epicardial patterns of activation on the ventricular wall do not always show spiral waves. We show that numerical simulations, even with a simple homogeneous excitable medium, can reproduce the key features of the simultaneous endo- and epicardial visualizations of propagating activity, and so these recordings may be interpreted in terms of scroll waves within the ventricular wall.

Suppression of Spiral Breakup in Excitable Media by Local Periodic Forcing

2016 ◽  
Vol 26 (14) ◽  
pp. 1650236
Author(s):  
Guiquan Liu ◽  
Heping Ying ◽  
Honglei Luo ◽  
Xiaoxia Liu ◽  
Jinghua Yang
Keyword(s):  
Ventricular Fibrillation ◽  
Numerical Simulations ◽  
Phase Diagrams ◽  
Cardiac Arrhythmia ◽  
Underlying Mechanism ◽  
Spiral Waves ◽  
Low Energy ◽  
Excitable Media ◽  
Periodic Forcing ◽  
Cardiac Tissues

Lowered excitability leads to unstable meandering of spiral tip, which result in breakup of spiral waves into chaotic states induced by Doppler effects. This phenomenon is responsible for the transition from tachycardia to ventricular fibrillation in cardiac tissues. Numerical simulations show that low-energy local periodic forcing (LPF) applied around spiral tip can efficiently suppress the meandering behavior and consequently prevent spiral breakup. The controllable phase diagrams that describe the amplitude and period of LPF against excitability parameter are presented to illustrate the control region. The underlying mechanism of suppressing spiral meandering behavior is explored by greatly decreasing the radius of the meandering tip. The proposed scheme can potentially contribute to controlling cardiac arrhythmia.

scholarly journals Spiral waves within a bistability parameter region of an excitable medium

2022 ◽  
Author(s):  
Vladimir Zykov ◽  
Eberhard Bodenschatz
Keyword(s):  
Initial Conditions ◽  
Three Dimensional ◽  
Spiral Wave ◽  
Gradient Flow ◽  
Spiral Waves ◽  
Excitable Medium ◽  
Excitable Media ◽  
Circular Trajectory ◽  
Parameter Region ◽  
Scroll Wave

Abstract Spiral waves are a well-known and intensively studied dynamic phenomenon in excitable media of various types. Most studies have considered an excitable medium with a single stable resting state. However, spiral waves can be maintained in an excitable medium with bistability. Our calculations, performed using the widely used Barkley model, clearly show that spiral waves in the bistability region exhibit unique properties. For example, a spiral wave can either rotate around a core that is in an unexcited state, or the tip of the spiral wave describes a circular trajectory located inside an excited region. The boundaries of the parameter regions with positive and "negative" cores have been defined numerically and analytically evaluated. It is also shown that the creation of a positive or "negative" core may depend on the initial conditions, which leads to hysteresis of spiral waves. In addition, the influence of gradient flow on the dynamics of the spiral wave, which is related to the tension of the scroll wave filaments in a three-dimensional medium, is studied.

Spiral waves in three-dimensional excitable media with light-sensitive reaction

2003 ◽  
Vol 18 (2) ◽  
pp. 365-373 ◽  
Author(s):  
E.M. Ortigosa ◽  
L.F. Romero ◽  
J.I. Ramos
Keyword(s):  
Three Dimensional ◽  
Spiral Waves ◽  
Excitable Media

scholarly journals Phase-resolved analysis of the susceptibility of pinned spiral waves to far-field pacing in a two-dimensional model of excitable media

2010 ◽  
Vol 368 (1918) ◽  
pp. 2221-2236 ◽  
Author(s):  
Philip Bittihn ◽  
Amgad Squires ◽  
Gisa Luther ◽  
Eberhard Bodenschatz ◽  
Valentin Krinsky ◽  
...  
Keyword(s):  
Local Control ◽  
Spiral Wave ◽  
Spiral Waves ◽  
Excitable Media ◽  
Excitation Threshold ◽  
Far Field ◽  
Life Threatening ◽  
Discontinuous Phase ◽  
Rotating Wave ◽  
Spatio Temporal

Life-threatening cardiac arrhythmias are associated with the existence of stable and unstable spiral waves. Termination of such complex spatio-temporal patterns by local control is substantially limited by anchoring of spiral waves at natural heterogeneities. Far-field pacing (FFP) is a new local control strategy that has been shown to be capable of unpinning waves from obstacles. In this article, we investigate in detail the FFP unpinning mechanism for a single rotating wave pinned to a heterogeneity. We identify qualitatively different phase regimes of the rotating wave showing that the concept of vulnerability is important but not sufficient to explain the failure of unpinning in all cases. Specifically, we find that a reduced excitation threshold can lead to the failure of unpinning, even inside the vulnerable window. The critical value of the excitation threshold (below which no unpinning is possible) decreases for higher electric field strengths and larger obstacles. In contrast, for a high excitation threshold, the success of unpinning is determined solely by vulnerability, allowing for a convenient estimation of the unpinning success rate. In some cases, we also observe phase resetting in discontinuous phase intervals of the spiral wave. This effect is important for the application of multiple stimuli in experiments.

Microstructures of Low Angle Boundaries of the Second Generation Single Crystal Superalloy DD6

2011 ◽  
Vol 284-286 ◽  
pp. 1584-1587
Author(s):  
Zhen Xue Shi ◽  
Jia Rong Li ◽  
Shi Zhong Liu ◽  
Jin Qian Zhao
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Thin Layer ◽  
Single Crystal ◽  
Second Generation ◽  
Three Dimensional ◽  
Single Crystal Superalloy ◽  
Transition Electron ◽  
Scanning Electron

The specimens of low angle boundaries were machined from the second generation single crystal superalloy DD6 blades. The microstructures of low angle boundaries (LAB) were investigated from three scales of dendrite, γ′ phase and atom with optical microscopy (OM), scanning electron microscope (SEM), transition electron microscope (TEM) and high resolution transmission electrion microscopy (HREM). The results showed that on the dendrite scale LAB is interdendrite district formed by three dimensional curved face between the adjacent dendrites. On the γ′ phase scale LAB is composed by a thin layer γ phase and its bilateral imperfect cube γ′ phase. On the atom scale LAB is made up of dislocations within several atom thickness.

SUPPRESSING SPIRAL WAVES IN EXCITABLE MEDIA VIA UNIDIRECTIONAL COUPLING

2008 ◽  
Vol 22 (24) ◽  
pp. 4153-4161 ◽  
Author(s):  
YU QIAN ◽  
YU XUE ◽  
GUANG-ZHI CHEN
Keyword(s):  
Co Oxidation ◽  
Power Law ◽  
Coupling Strength ◽  
Control Method ◽  
Spiral Waves ◽  
Coupling Method ◽  
Excitable Media ◽  
Catalytic Co Oxidation ◽  
Unidirectional Coupling ◽  
High Control

A unidirectional coupling method to successfully suppress spiral waves in excitable media is proposed. It is shown that this control method has high control efficiency and is robust. It adapts to control of spiral waves for catalytic CO oxidation on platinum as well as for the FHN model. The power law n ~ c-k of control time steps n versus the coupling strength c for different models has been obtained.

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