Functional Characteristics of Antioxidant Long-Life Ultra-Fine Bubble Hydrogen Water
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript reported functional characteristics of antioxidant long-life ultra-fine bubble hydrogen water. Some comments are given as follows:
Comment (1): Some related literatures should be cited in line 159-165. Some related literatures are given as follows:
[1] <an ultrasonic vibration method> The effect of ultrasound on bulk and surface nanobubbles: A review of the current status, Ultrasonics Sonochemistry,Volume 76, August 2021, 105629
[2] < a pressurization-depressurization method> Aqueous dispersions of nanobubbles: Generation, properties and features, Minerals Engineering 94 (2016) 29–37
[3] < a venturi tube method> The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation, Ultrasonics Sonochemistry 2022 Vol. 84 Pages 105965
[4] < a gas-liquid swirling two-phase method> CFD-PBM approach for the gas-liquid flow in a nanobubble generator with honeycomb structure. J. Dispers. Sci. Technol. 2019, 40, 306–317; Numerical Simulation and Structural Optimization of Swirl Flow Micro-Nano Bubble Generator, Coatings 2023, 13(8), 1468
Comment (2): Where is Figure 5?
Comment (3): According to the authors’ patent, the air bubbles having the size of 20-1 μm or less is called an ultra-fine bubble. In the patent, the authors also mentioned microbubbles. However, in the current study, the related characterization and discussion of microbubbles is missing. If the author equates micro bubbles with nanobubbles, suitable explanation must be given in the revised manuscript.
Comment (4): Check and correct the format of the references.
Comment (5: Grammatical corrections in the manuscript should be needed.
Comment (6): Please rewrite the conclusion as it was not addressed in any future scope of this work.
Comment (7): The author has applied for a patent for this method of generating hydrogen bubbles. As a research article, readers would prefer to see the author's research on bubble size, concentration, and antioxidant functional characteristics under different operating conditions
Comment (8): What are the innovative points of work? Include your arguments in the manuscript.
Comment (9): Unless the author provides more detailed results on the impact of operational parameters, the paper only can be published as a case report.
If the following issues are solved completely, this work might be positively considered for publication.
Comments on the Quality of English LanguageGrammatical corrections in the manuscript should be needed.
Author Response
We would like to thank you for your detailed review of our manuscript and your helpful comments. The revised parts are shown in blue.
Comment (1): Some related literatures should be cited in line 159-165. Some related literatures are given as follows:
[1] <an ultrasonic vibration method> The effect of ultrasound on bulk and surface nanobubbles: A review of the current status, Ultrasonics Sonochemistry,Volume 76, August 2021, 105629
[2] < a pressurization-depressurization method> Aqueous dispersions of nanobubbles: Generation, properties and features, Minerals Engineering 94 (2016) 29–37
[3] < a venturi tube method> The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation, Ultrasonics Sonochemistry 2022 Vol. 84 Pages 105965
[4] < a gas-liquid swirling two-phase method> CFD-PBM approach for the gas-liquid flow in a nanobubble generator with honeycomb structure. J. Dispers. Sci. Technol. 2019, 40, 306–317; Numerical Simulation and Structural Optimization of Swirl Flow Micro-Nano Bubble Generator, Coatings 2023, 13(8), 1468
→ Thank you for your comments. According to your suggestion, five references have been added to the revised manuscript (L447~L458; reference No. 12~16).
Comment (2): Where is Figure 5?
→ It was a mistake. The description has been revised to Figure 3 (L177).
Comment (3): According to the authors’ patent, the air bubbles having the size of 20-1 μm or less is called an ultra-fine bubble. In the patent, the authors also mentioned microbubbles. However, in the current study, the related characterization and discussion of microbubbles is missing. If the author equates micro bubbles with nanobubbles, suitable explanation must be given in the revised manuscript.
→ Thank you for your comments. Previous studies of microbubbles and nanobubbles as ultrafine particles were also introduced in this report, where microbubbles and nanobubbles are tentatively defined based on bubble size (L189~L201). The average bubble size of the hydrogen water used in this study is about 60 nm (Fig. 3) and is defined as UFB. An explanation of the UFB in this study has been added to the revised manuscript (L56~L62; L201~L205).
Comment (4): Check and correct the format of the references.
→ The format of the references has been unified.
Comment (5: Grammatical corrections in the manuscript should be needed.
→ English editing was carried out.
Comment (6): Please rewrite the conclusion as it was not addressed in any future scope of this work.
→ The conclusions have been revised (L396~L402).
Comment (7): The author has applied for a patent for this method of generating hydrogen bubbles. As a research article, readers would prefer to see the author's research on bubble size, concentration, and antioxidant functional characteristics under different operating conditions.
→ Thank you for your comments. In this study, UFB hydrogen water was prepared based on a US patent. However, at the time of the patent application, there were insufficient methods to assess the size and concentration of UFB, and no mention was made of the stability of its antioxidant capacity. The present study reports more clearly on the properties of UFB hydrogen water. These points have been added to the discussion (L161~L162; L206~L207; L219~L220).
Comment (8): What are the innovative points of work? Include your arguments in the manuscript.
→ Regarding the issues you pointed out, we have added an additional description to the discussion (L180~L188).
Comment (9): Unless the author provides more detailed results on the impact of operational parameters, the paper only can be published as a case report.
→ UFB water was prepared by a combination of resonant foaming and vacuum cavitation. Typical measurements of the comparative results of air content in bubbles from resonance foaming alone and from the combination of resonance foaming and vacuum cavitation are shown in Table 3. A description relating to these results has been added (L332 ~ L342).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsI assess this manuscript high. It is interesting subject and very challenged. I have some comments/questions:
1. "We have developed a method for producing more stable hydrogen water by encapsulating hydrogen in UFB with a bubble size of less than 1 um [9]." Please, indicate clearly: waht is new/different in comparison to the last technique of hydrogen water prodution.
2. The Authors assessed stability of the hydrogen water by measuring oxidation potential, it is clear. I am more interested how the concentration of UFB (Figure 3) looks after several days.
3. The Authors named the bubbles hydrogen water as encapsulation of hydrogen. I think more accurate is to name it as dispersion of hydrogen in water.
Author Response
I assess this manuscript high. It is interesting subject and very challenged. I have some comments/questions:
We appreciate your high evaluation of our submitted manuscript. We have responded to your comments and questions below. The revised parts are shown in blue.
1. "We have developed a method for producing more stable hydrogen water by encapsulating hydrogen in UFB with a bubble size of less than 1 um [9]." Please, indicate clearly: waht is new/different in comparison to the last technique of hydrogen water prodution.
→ Regarding the issues you pointed out, we have added an additional description to the discussion (L180~L188).
2. The Authors assessed stability of the hydrogen water by measuring oxidation potential, it is clear. I am more interested how the concentration of UFB (Figure 3) looks after several days.
→Thank you for the comments. The bubble concentration shown in Fig. 2 was maintained even after 3 months. We added this point to the results (L206~L207).
3. The Authors named the bubbles hydrogen water as encapsulation of hydrogen. I think more accurate is to name it as dispersion of hydrogen in water.
→ We have carefully considered your comments and revised the notation in the revised manuscript (L18~L19; L56~L58; L397~L398).
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAccept.
