Fluorescence Properties of Pterocarpus Wood Extract
Round 1
Reviewer 1 Report
The manuscript entitled “Fluorescence properties of Pterocarpus wood extractive” presents studies concerning the fluorescence of wood extracts, obtained with different extraction solvents. The authors describe LC-MS and fluorescence spectroscopy analyses, as well as the effect of parameters such as pH and concentration on the emission characteristics of the system. Nevertheless, the quality of the presentation is quite low, with very confusing sections and passages describing widely known phenomena, without originality. Furthermore, the authors do not frame their work in an appropriate context, limiting the interest of the presented work. I’ve addressed some particular aspects related to this in the comments below, and do not consider the manuscript fit for publication.
· Title: “extract” would be a more accurate term than “extractive”. This should be considered throughout the whole manuscript.
· Although understandable considering that the authors are non-native English speakers, but considering this is the publication language, an important revision of the language and syntax is required for the whole manuscript.
· Introduction: More context on the importance of studying the fluorescence (and the molecules responsible for it) of Pterocarpus extracts is necessary. As presented, the importance of the developed work is not clear (besides the fact of advancing previous studies).
· Introduction: The description of the fluorescence phenomenon should be improved (e.g.: it seems to point out that all molecules are fluorescent, or that the fact that the instrumental detection is performed at 90o from the light source does not imply that fluorescence occurs only in this direction).
· Methods: The experimental stages should not be written as instructions.
· Section 2.3.2. General expressions such as “after a lot of pre-experiments” should be avoided. What is “a lot of pre-experiments”? Please provide specific information.
· Section 3.1.1. The authors state that “It can be seen that the intensity of fluorescence in different solvents is also different”, but this is not observable in the pictures.
· Section 3.1.1. The authors mention “the fluorescent molecule exists in the heartwood..”, but later on show that more than one molecule is responsible for the fluorescence of the system.
· Figure 2: The authors should consider enlarging the text to improve visualization.
· Figure 2: The figure caption indicates that (a) and (b) represent spectra taken at different times, but (a) (b) seem to show spectra obtained with different excitation wavelengths. The inverse happens with (c) and (d).
· Section 3.1.2: “We analyzed the extracts one by one for substances with a ratio of more than 5×104“ What does this mean?
· Section 3.1.2: The section title mentions LC-MS results, but general fluorescence results are prominent in this section. There is practically no description of the LC-MS results, except from a table of molecule structures which does not have a clear explanation.
· Section 3.1.2: “After that, we simply start from the chemical structure of each substance, one by one analysis, list the five most likely molecules and their structures”. What does this mean?
· Section 3.1.3. The first sub-section is numbered “333.1.3”
· Section 3.1.3. Again, general inaccurate expression such as “The photons released by the irradiated light contain huge energy, …” How much is “huge energy”? This sentence also mentions that photons “contact” the irradiated material, a very erroneous expression.
· The description of the fluorescence mechanism in section 3.1.3 is no more than a general description of fluorescence, and does not represent anything new. Furthermore, the authors describe the process as a FRET process, which is not correct, since FRET occurs between different chromophores, not within a single molecule.
· Section 3.2: “ Based on the previous description of the fluorescence mechanism, we selected four substances with the strongest fluorescence according to the chemical molecular formula of each substance for testing.” This seems to indicate that the fluorescence was somehow inferred from the molecular structures; was this experimentally verified?
· Several expressions lack chemical sense; for example: “It can be seen that the fluorescence properties of these two substances can be fully excited in TCM solvent system.”. What does “fully exciting the fluorescence properties” mean?
· Many globally-known facts are repeated throughout the text, such as the differences observed in the fluorescence spectra obtained in different solvents. This is not new and should not be considered a specific characteristic of this system or these molecules.
· Section 3.3: “In order to explore the stability of the fluorescence properties of this substance, we repeatedly destroyed its pH conditions and recovered” What do the authors mean by “destroying the pH conditions”?.
· Section 3.3: The authors state that: “we used different acid-base substances for pH adjustment”, but the methods section only describes the use of NaOH and HCl.
· Section 3.4. The authors describe two aggregation induced behaviors: quenching and emission, but then state that in both cases the emission intensity decreases with aggregation. This is not the case of AIE, in which the emission is increased by aggregation.
· Section 3.4. Besides aggregation-based mechanisms, the authors should consider the simpler -albeit more common- auto-absorption phenomenon to explain the decrease in the expected emission intensity as the concentration of the fluorescent molecule increases beyond a certain threshold.
· Conclusions: The authors state that the effect of temperature on the emission was studied, but this has not been included in the results.
Author Response
Please see the attachment. Thank you very much for your patience in reviewing it. My article leaves a lot to be desired. I have made an effort to revise it. The main changes include the correction of language and formatting errors and the improvement of the content of the paper. One of the main additions to the content of the paper is the effect of auto-absorption phenomenon on fluorescence intensity, consideration of the effect of protonation -deprotonation phenomenon on fluorescence intensity when pH is changed, etc. This will enrich our content. We hope to achieve a better result after further revision. Thank you again for your suggestions on how to revise our paper, it is very important to us. Sorry for the minor problems with the previous paper. I would also like to thank you for evaluating our revised essay again.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors
After carefully reading your manuscript, I can say that it contains good information and some novelty. I have the following comments and suggestions to help you review your manuscript.
1. English is not the best, and you need to let a native English speaker revise it. There are many grammatical mistakes and you always use the "we did...", instead you need to write it as "was done...., was added, ....I also should say that the use of "respectively" in your manuscript is wrong. Make sure that punctuations are added correctly.
2. As for the Introduction, I could not see anything about the plant (wood) itself as the origin, characteristics, shape, ..... and so on.
3. The aim of the work should appear at the end of the Introduction. Line 55, should belong to the aim. Also, please note that lines 60-61 are results, but not Introduction.
4. In the materials and methods, 2.1 Materials is a long sentence. Please rewrite it and make sure not to use long sentences. (in many other places as well).
5. Line 87, you use the word solution, I think it should be extraction. Lines 91-93 are repeated. Please omit them. Remove the word afterwards in line 90. As mentioned before, please write that for example: pH was measured and .... instead: Measure the pH (line 97, and all other places in the manuscript, e.g. lines 101, 108, 113, 114, 142, 160,175, 178,187.....).
6. No need for line 127. It is the usual procedure in research.
7. Line 190, I did not understand the sentence: ....with a ratio of more than 5x104. Line 200-201 are also not clear! What is meant by them?
8. Please correct the numbering in line 206.
9. The legend of Figure 3 (lines 263-267) is too long, it can be simplified.
10. Lines 269-270 need reference(s).
11. Figure 4 a and c, use the word Adding instead of Added.
12. Please check lines 278-283 and rewrite them in a more understandable way.
13. Lines 284-293 when discussing the pH effect, is there any protonation - deprotonation leading to the intensity?
14. Line 291: What are the acids and bases used in the pH adjustment, you might add them in brackets.
15. Rephrase line 311-313.
16. Line 322, delete the phrase "through some analysis and research" and do not use the word "we".
17. The Conclusion should be checked to summarize the results. Also, English should be checked here as well.
18. Line 330 says that you researched the effect of temperature! I could not see anything about the temperature effect in the manuscript. Please check!
19. References: Please be consistent in writing the references as per the regulations of the journal. The journal, as I checked, does not mention that you need to use "et. al." after a given number of authors. What I saw is that all authors should be included. Additionally, the publication year should be in BOLD. Also, there is no year in reference 19.
All the best.
Author Response
Please see the attachment. Thank you very much for your patience in reviewing it. My article leaves a lot to be desired. I have made an effort to revise it. The main changes include the correction of language and formatting errors and the improvement of the content of the paper. One of the main additions to the content of the paper is the effect of auto-absorption phenomenon on fluorescence intensity, consideration of the effect of protonation -deprotonation phenomenon on fluorescence intensity when pH is changed, etc. This will enrich our content. We hope to achieve a better result after further revision. Thank you again for your suggestions on how to revise our paper, it is very important to us. Sorry for the minor problems with the previous paper. I would also like to thank you for evaluating our revised essay again.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript presents possible species of fluorescent molecules in the extracts of Pterocarpus wood. The effects of solvent type, pH, and concentration on the fluorescence of the extracts were investigated.
The study is interesting, however, some presentations and discussions related to the experimental results still have room for improvement.
In lines 261-261, the authors described: “All systems contain Naptalam with great fluorescence intensity, and whether it exists in Pterocarpus wood needs further study.” Thus, in this study, the analysis of Naptalam fluorescence in different solvent systems is of little significance.
The caption of Fig. 2 should be revised.
Check the MLQ and MWQ in Fig. 3.
For the fluorescence spectra of ethanol system, the peak position in Fig. 2(b) is different with that in Figs. 2(d) and 2(e); which should be illustrated.
Author Response
Please see the attachment. Thank you very much for your patience in reviewing it. My article leaves a lot to be desired. I have made an effort to revise it. The main changes include the correction of language and formatting errors and the improvement of the content of the paper. One of the main additions to the content of the paper is the effect of auto-absorption phenomenon on fluorescence intensity, consideration of the effect of protonation -deprotonation phenomenon on fluorescence intensity when pH is changed, etc. This will enrich our content. We hope to achieve a better result after further revision. Thank you again for your suggestions on how to revise our paper, it is very important to us. Sorry for the minor problems with the previous paper. I would also like to thank you for evaluating our revised essay again.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The revised version of the manuscript entitled “Fluorescence properties of Pterocarpus wood extract” represents a very significant improvement by the authors, although there are still some issues that can be improved (please see the comments below). Furthermore, considering the responses to my original comments, I believe that most of the weak aspects of this work are not a consequence of low-quality research or data analysis, but of English language expression. I therefore recommend the authors to further check the use of English throughout the manuscript, or consider a revision from a native speaker, which would (I believe) clarify most of the aspects I comment on below. Being a non-native English speaker myself, I fully understand the difficulties when facing English publishing, but given the fact that this is the journal’s publication language, it has to be considered seriously.
Introduction. The section has been improved in comparison to the original version, but the quality of English needs to be checked to make the reading more fluid.
Experimental Section: Several tenses (past, present, imperative) are mixed throughout the section.
Section 2.2.1 – Line 96: The method is described as an instruction, rather than as a performed experiment. The same happens in Section 2.2.2 – Line 112, Section 2.2.3 – Line 119, Section 2.2.5 – Line 135.
Section 2.2.1 - Lines 102-105: These three sentences seem to say the same thing.
Section 3.1.1 – Line 188: “NH” and “MQW-H” have not been defined in the text. I can see they are defined in a figure caption, but it would be better for the reader to define all of the used abbreviations in the main text, before their first use.
Section 3.1.2 – Lines 202-216: If the authors believe that a description of the fluorescence and FRET mechanisms is necessary, it would probably be better situated in the introduction instead than in the results and discussion section.
Section 3.1.2 – Lines 225-226. What does the expression “This shows that the movement of electrons in molecules with rigid structures may have a more definite law” mean?
Section 3.1.2 – Lines 228-229. The authors state that the emission wavelength is enhanced by the presence of some functional groups. I believe a more appropriate term would be “shift”.
Section 3.1.3 – Line 245: Which are the molecules found in the cited work?
Section 3.1.3 – Lines 250-250. The authors state that “Different wavelengths of incident wave excitation give different intensities of fluorescent emission waves (Figure 2a,2b). This indicates that the molecules that produce fluorescence are present at high levels in the extracts.”. They should clearly indicate how they concluded that the concentration of fluorophores was high from the fact that the emission is excitation-dependent (which is not a concentration-dependent phenomenon).
Section 3.1.3 – Line 252. The authors state that “LC-MS results were so large”. What is large LC-MS results?
Section 3.1.3: The authors state that the emission wavelength increases as the number of molecules with large conjugated systems increases (lines 262-263), and then indicate that a reduction in the number of conjugated molecules in the case of ethanol increases the emission wavelength (lines 270-272). This is contradictory.
There are two sections identified as 3.4.
Author Response
Please refer to the attachment. Thank you very much for your patience in reviewing this article. My article leaves a lot to be desired. I have tried to modify it. This revision mainly corrects errors in tenses and expressions. Due to my poor English, there are many sentences in the article that are prone to ambiguity. For this, I sincerely apologize. I hope my revisions will lead to better results. Thanks again for your patience and guidance. May you be well!
Author Response File: Author Response.pdf
Reviewer 2 Report
Dear Authors
I think that your revision to the manuscript made it much better, and after going through, I found that you did all what was asked from my side.
Thanks and best regards
Author Response
Hello! Thank you so much for checking out my article again. Thank you for your approval, I have revised some of the language again, including tense, expression and so on. Hopefully these changes will make the article better. I've marked the second change in blue. Thanks again for your careful review. Best wishes and thanks!
