Design of non-autonomous pH oscillators and the existence of chemical beat phenomenon in a neutralization reaction

Abstract

The beat in physical systems is a transparent and well-understood phenomenon. It may occur in forced oscillatory systems and as a result of the interference of two waves of slightly different frequencies. However, in chemical systems, the realization of the latter type of the beat phenomenon has been lacking. Here we show that a periodic titration of acid and alkaline solutions with each other using programmable syringe pumps in a continuous stirred-tank reactor exhibits the beat phenomenon in the temporal pH oscillation pattern if the time periods of sinusoidal inflow rates of the reagents are slightly different. Interestingly, the frequency of the chemical beat pattern follows the well-known relationship from physics, namely the frequency of the beat is equal to the absolute value of the difference of the two wave frequencies. Based on our strategy, we can design and engineer non-autonomous pH oscillatory systems, in which the characteristics of the temporal oscillations (amplitude, time period) can easily and precisely be controlled by the experimental conditions such as the inflow rates and feed concentrations. The demonstrated phenomena can be exploited in practical applications, we use the non-autonomous pH oscillators to drive the reversible assembly and disassembly of pH-sensitive building blocks (oleic acid and gold nanoparticles), both highly relevant in nanotechnology and biomedical applications.

Reaction–Diffusion Dynamics of pH Oscillators in Oscillatory Forced Open Spatial Reactors

“…When the time period of the forcing was too low compared to the natural time period of the system and the residence time of the chemical species, the forcing did not affect the characteristics of the system. In addition to this, similar behavior was found in a neutralization reaction when an acid solution was titrated periodically in antiphase with an alkaline solution in a CSTR by using various periodic inflow rate functions of the reagents . Our simulations, made in spatially extended systems, confirmed that periodic boundary conditions created by low-frequency forcing on the CSTR part might result in the modulation of spatiotemporal oscillations and forced spatiotemporal bursting in the gel part.…”

“…In addition to this, similar behavior was found in a neutralization reaction when an acid solution was titrated periodically in antiphase with an alkaline solution in a CSTR by using various periodic inflow rate functions of the reagents. 34 Our simulations, made in spatially extended systems, confirmed that periodic boundary conditions created by low-frequency forcing on the CSTR part might result in the modulation of spatiotemporal oscillations and forced spatiotemporal bursting in the gel part. Synchronization can also be observed at high-frequency forcing in a TSFR.…”

Statistical and sequence learning lead to persistent memory in children after a one-year offline period

“…To control for the effect of average RT differences related to age on learning and consolidation of knowledge, we transformed the data in the following way. We divided each participants’ raw RT values of each trial type and each epoch by their own average performance (i.e., average RT) in the first epoch of the task [for a similar approach, see 51 , 52 ]. Participants’ performance was around 1 at the beginning of the task and changed as the task progressed.…”

pH-feedback systems to program autonomous self-assembly and material lifecycles

“…Although H + -producing and consuming steps are seen, no autocatalysis pathway has been identified so far. [45][46][47][48] Towards higher complexity in inorganic networks, multifeedback pH-oscillation systems, oscillation amplification, oscillation elimination, 49 beat phenomenon, 50 and synchronization 51 were achieved successfully in recent years. Subsequently, moving towards organic CRNs, Taylor and co-workers introduced the first experimental example of an organic-based pH-oscillator utilizing the base-catalysed dehydration of methylene glycol as a source of positive feedback (OH À autocatalysis) This journal is © The Royal Society of Chemistry 2023 coupled with the base-catalysed hydrolysis of gluconic acid d-lactone (d-GL) for negative feedback (H + production).…”