Thermal switch of oscillation frequency in Belousov-Zhabotinsky liquid marbles

External control of oscillation dynamics in the Belousov-Zhabotinsky reaction is important for many applications including encoding computing schemes. When considering the BZ reaction there are limited studies dealing with thermal cycling, particularly cooling, for external control. Recently, liquid marbles (LMs) have been demonstrated as a means of confining the Belousov-Zhabotinsky reaction in a system containing a solid-liquid interface. BZ LMs were prepared by rolling 50 {\mu}l droplets in polyethylene (PE) powder. Oscillations of electrical potential differences within the marble were recorded by inserting a pair of electrodes through the LM powder coating into the BZ solution core. Electrical potential differences of up to 100mV were observed with an average period of oscillation ca. 44 s. BZ LMs were subsequently frozen to -1oC to observe changes in the frequency of electrical potential oscillations. The frequency of oscillations reduced upon freezing to 11mHz cf. 23mHz at ambient temperature. The oscillation frequency of the frozen BZ LM returned to 23mHz upon warming to ambient temperature. Several cycles of frequency fluctuations were able to be achieved.

Have you any concerns about statistical analyses in this paper? I do not feel qualified to assess the statistics

Recommendation? Accept with minor revision (please list in comments)
Comments to the Author(s) This is an important paper because it reveals a new tractable approach to controlling the behavior of BZ. Furthermore, by focusing their efforts on the BZ liquid marble formulation, the authors have developed a pathway for control that can be controlled in a modular fashion.
Do the authors have any consideration about what would happen if microdroplets were frozen (e.g., Wang et al 2016 EPJ)? The ratio of change in length scale would be notably larger and could be sufficient to toggle information transmission between inhibitory coupling and activating coupling.
Have the authors attempted to combine this method with photosensitive BZ? Can other input methods be used at the same time as freezing?
Oscillations look more irregular after freezing. How does this impact the potential to use freezing/frozen liquid marbles in a computational circuit?
How does freezing affect the longevity of oscillatory behavior in LMs? That is, do frozen droplets oscillate the same number of times as non-frozen LMs?
It would be interesting to see some numbers that describe the variability of LM behavior after freezing. How consistent and/or predictable is their behavior?
It would also be interesting to see a comparison between the surface simulations and an surface reconstruction. However, this seems likely to be more appropriate for a subsequent effort. Simulation code is used, but no link is provided. The authors have shared their code in previous papers, so this is clearly a simple oversight.

Review form: Reviewer 2
Is the manuscript scientifically sound in its present form? Yes

Recommendation?
Accept with minor revision (please list in comments)

Comments to the Author(s)
The manuscript entitled "Thermal switch of oscillation frequency in Belousov-Zhabotinsky liquid marbles" authored by A. Adamatzky, C. Fullarton, T. Draper, N. Philips and B. de Lacy Costello describes temperature effect on period of oscillations in Belousov-Zhabotinsky (BZ) droplets coated with polyethylene powder (named here as liquid marbles (LMs)) . Authors claim that this phenomena can be useful as a control method in information processing devices based on BZ LMs. As attention towards new unconventional computing methods is growing the topic seems interesting. The manuscript needs revision before publication. It might be suitable for publication in Royal Society Open Science upon minor changes 1. In the first section authors mention that "BZ-LMs also provide the possibility for active transport processes which is not easily possible with vesicles". It would be helpful if the authors explain what they mean by active processes in BZ-LMs (and why it is hard to realise with vesicles) or give at least some literature reference.
2. For implementing some useful computing functionality larger number of the BZ LM's is required. With the presented thermal control method I see no possibility of oscillation control of individual LM's in an ensemble. Another question is how temperature difference influence affects mechanical stability of BZ LMs? Do authors expect other problems if the present method is applied for a structure similar to this from ref. 41? I think it would be fair to the readers to discuss these and other potential problems with thermal control of BZ LMs. 5. All the figures would be easier to follow if the time axis are changed to seconds, especially that all of the times and period in the text are given in seconds.
6. There are some small issues, which I`ve noticed, and which could help the Authors with polishing the manuscript: -phrase repetitions line 36 page 5 "are as follows are analysed". Line 43 page 7 "This is is reflected" -According to caption of Fig.4a it was kept cool until the end of experiment. Why # symbol is visible at t = 900 s?

11-Mar-2019
Dear Dr Adamatzky On behalf of the Editors, I am pleased to inform you that your Manuscript RSOS-190078 entitled "Thermal switch of oscillation frequency in Belousov-Zhabotinsky liquid marbles" has been accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the referees' comments at the end of this email.
The reviewers and handling editors have recommended publication, but also suggest some minor revisions to your manuscript. Therefore, I invite you to respond to the comments and revise your manuscript.
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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch. Comments to the Author(s) This is an important paper because it reveals a new tractable approach to controlling the behavior of BZ. Furthermore, by focusing their efforts on the BZ liquid marble formulation, the authors have developed a pathway for control that can be controlled in a modular fashion.
Do the authors have any consideration about what would happen if microdroplets were frozen (e.g., Wang et al 2016 EPJ)? The ratio of change in length scale would be notably larger and could be sufficient to toggle information transmission between inhibitory coupling and activating coupling.
Have the authors attempted to combine this method with photosensitive BZ? Can other input methods be used at the same time as freezing?
Oscillations look more irregular after freezing. How does this impact the potential to use freezing/frozen liquid marbles in a computational circuit?
How does freezing affect the longevity of oscillatory behavior in LMs? That is, do frozen droplets oscillate the same number of times as non-frozen LMs?
It would be interesting to see some numbers that describe the variability of LM behavior after freezing. How consistent and/or predictable is their behavior?
It would also be interesting to see a comparison between the surface simulations and an surface reconstruction. However, this seems likely to be more appropriate for a subsequent effort.
Simulation code is used, but no link is provided. The authors have shared their code in previous papers, so this is clearly a simple oversight.

Reviewer: 2
Comments to the Author(s) The manuscript entitled "Thermal switch of oscillation frequency in Belousov-Zhabotinsky liquid marbles" authored by A. Adamatzky, C. Fullarton, T. Draper, N. Philips and B. de Lacy Costello describes temperature effect on period of oscillations in Belousov-Zhabotinsky (BZ) droplets coated with polyethylene powder (named here as liquid marbles (LMs)) . Authors claim that this phenomena can be useful as a control method in information processing devices based on BZ LMs. As attention towards new unconventional computing methods is growing the topic seems interesting. The manuscript needs revision before publication. It might be suitable for publication in Royal Society Open Science upon minor changes 1. In the first section authors mention that "BZ-LMs also provide the possibility for active transport processes which is not easily possible with vesicles". It would be helpful if the authors explain what they mean by active processes in BZ-LMs (and why it is hard to realise with vesicles) or give at least some literature reference.
2. For implementing some useful computing functionality larger number of the BZ LM's is required. With the presented thermal control method I see no possibility of oscillation control of individual LM's in an ensemble. Another question is how temperature difference influence affects mechanical stability of BZ LMs? Do authors expect other problems if the present method is applied for a structure similar to this from ref. 41? I think it would be fair to the readers to discuss these and other potential problems with thermal control of BZ LMs. Fig. 2c in this experiment oscillations were induced with a silver wire. Please add information about purpose of silver wire stimulation to Methods section. Fig. 3d it would be helpful if the moments of time at which Peltier was on and off are also marked (as in Fig 3a with * and # symbols).

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5. All the figures would be easier to follow if the time axis are changed to seconds, especially that all of the times and period in the text are given in seconds.
6. There are some small issues, which I`ve noticed, and which could help the Authors with polishing the manuscript: -phrase repetitions line 36 page 5 "are as follows are analysed". Line 43 page 7 "This is is reflected" -According to caption of Fig.4a  Decision letter (RSOS-190078.R1)

27-Mar-2019
Dear Dr Adamatzky, I am pleased to inform you that your manuscript entitled "Thermal switch of oscillation frequency in Belousov-Zhabotinsky liquid marbles" is now accepted for publication in Royal Society Open Science.
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