Multiscale Characterization of Isotropic Pyrolytic Carbon Used for Mechanical Heart Valve Production
, Mattia Gusmini 1,2, Alberto Luigi Audenino 1,2, Giovanni Bergamasco 3, Ornella Ieropoli 3 and Cristina Bignardi 1,2Round 1
Reviewer 1 Report
Major concern: there was a lack of novelty in the idea explored and there was no clear justification of why was this study relevant to pursue.
Minor concerns:
Consider changing the key words (different to words that already appear in title). Key words are used for metadata.
Page 1, line 24. Authors must specify if the 300,000 patients that undergo heart valve replacement is a global statistic or from the US, etc. clarify.
Introduction is composed of unusually seen short paragraphs. Group these short paragraphs by topic to compose longer paragraphs.
Page 1, line 45. Consider rewriting the sentence starting with “Satisfying hardness values…” for clarity.
Page 2, line 47. Consider rewriting the sentence starting with “For the sake of the exposition…” for clarity.
In introduction, line 84. Replace “porous” with “pores”.
In the Appendix, Tables should include a footnote detailing what the abbreviations (e.g., Ri, t, b, d, etc.) stand for.
Line 129. Dimensions of the specimens appear in Tables A1 and A2, but there is no explanation of how the specimens were measured.
Line 134. Could the authors explain what the ‘normative’ geometry is?
Line 137. It is not clear what ye is, and it is not marked in Figure 2 schematic. Wouldn’t it be less confusion to describe R as the radius? Something like: R is the radius from the centreline of the specimen.
Line 147. It is unclear what “the virtual work” means.
Figures. To improve clarity in the manuscript, authors could change the name of their groups from “old/new” processes to more descriptive names in the graphs of the Figures (and ensure consistency throughout the manuscript).
Figure 7. To make it easier to the reader, authors could use the same scale (up to 1000 nm) in the x-axis.
Author Response
The authors want to thank the reviewer for the useful comments and time spent to revise the draft of the manuscript.
Please find the response to the comments in the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper is interesting and within the scope of Processes journal. The authors present the two approaches of pyrolytic carbon deposition and characterization of obtained surfaces at the macro and micro scale in order to understand how the variation of coating rate impacts on the mechanical properties of the deposited layers.
The manuscript content and science is presented in an appropriate manner. The methods are completely detailed. A comparison with methods with different deposition time is performed to explain the obtained results. Although now macrospic defferences between methods were detected, the reduction of the difference of the nanomechanical properties between the inner and outer layers was registered, what could positively influence performance of such PyC layers.
Based on the comments mentioned above I recommend this manuscript to be published as received, without corrections.
Author Response
The authors appreciate that the reviewer enjoyed the work and they are grateful for his/her comments and time, spent to revise the manuscript.
Reviewer 3 Report
The manuscript entitled "Multiscale Characterization of Isotropic Pyrolytic Carbon Used for Mechanical Heart Valves Production" shows a study on the mechanical properties of MHV coated with PyC using different methods: the old or traditional method and a modified method which accounts for a reduced coating rate only at the first hour of deposition. The authors also evaluated the two coating methods at the micro and macro scale. The manuscript was well written, and English spelling and style require few or minor reviews. The study was based on two tests: three-point bending and nanoindentation. The results are impressive as it shows that although Young's modulus did not significantly change, the strength required to provoke a fracture was increased by using the new method. The nanomechanical properties revealed a slight reduction in the elastic properties of PyC layers.
Minor Review Required:
1. The discussion section can be improved by exploring the effects of the new coating method on the manufacturing of MHV and commenting on the expected clinical outcomes (e.g. how the new coating and the improved mechanical properties will/could affect the deposition of proteins at the device's surface? How can the new mechanical properties that were achieved by the new coating method affect the in vivo performance of the MHV? How the new coating method influences the stability of MHV?)
2. Please include a Conclusion section. The audience would benefit from the author's perspective on the design of the study and the results. It is also important to comment on the benefits or drawbacks of the new PyC coating method for manufacturing and application purposes. The audience would also be interested in the authors' suggestions on additional studies and the future directions the study can take.
Author Response
The authors want to thank the reviewer for the useful comments and time spent to revise the draft of the manuscript.
Please find the response to the comments in the attachment.
Author Response File: Author Response.pdf
