Fondazione Bruno Kessler is developing a mobile app prototype for empowering citizens to improve their health conditions through different lifestyle interventions that will be incorporated into a mobile application for lifestyle promotion of the Province of Trento in the context of the Trentino Salute 4.0 Competence Center. The envisioned interventions are based on promoting behaviour change in various domains such as physical activity, mental health and nutrition. In particular, the nutrition component is a self-monitoring module that collects dietary habits to analyse them and recommend healthier eating behaviours. Dietary assessment is completed using a Food Frequency Questionnaire on the Mediterranean diet that is presented to the user as a grid of images. The questionnaire returns feedback on 11 aspects of nutrition. Although the questionnaire used in the application only consists of 24 questions, it still could be a bit overwhelming and a bit crowded when shown on the screen. In this paper, we tried to find a machine-learning-based solution to reduce the number of questions in the questionnaire. We proposed a method that uses the user’s previous answers as additional information to find the goals that need more attention. We compared this method with a case where the subset of questions is randomly selected and with a case where the subset is chosen using feature selection. We also explored how large the subset should be to obtain good predictions. All the experiments are conducted as a multi-target regression problem, which means several goals are predicted simultaneously. The proposed method adjusts well to the user in question and has the slightest error when predicting the goals. Food Frequency Questionnaires (FFQs) are inexpensive and probably one of the most commonly used dietary tools for self-assessment. Therefore, several applications incorporate FFQs to monitor dietary habits ,2. For eThe FFQ in the LBC application is based on a Mediterranean diet, which has been shown to have a wide range of benefits for health , for insAlthough performing well, most automated approaches for generating or adapting FFQs rely heavily on expert knowledge. For instance, Molag et al.  developeIn our previous work, we explored a few approaches that could help automate the development of FFQs and adjust the questionnaires to the users’ needs. So far, we have worked on single-target problems, trying to predict only one nutrition aspect at a time. First, we explored the ranking of questions in FFQs , which cIn this paper, we explore different approaches to reduce the number of questions shown on the screen in the LBC mobile application. We consider the problem of predicting the quality of several nutrition aspects from the questionnaire as a multi-target regression problem, which means we predict several values simultaneously ,17. We pThe FFQ used in this paper follows the principles of the Mediterranean diet and is currently implemented in the LBC application  developequestions for food items from this point on.The questionnaire asks the user about the daily consumption of 24 food items: bread, pasta, breakfast cereals, baked sweets, potatoes, fruit, vegetables, red meat, white meat, fish, conserved fish, eggs, lentils, milk/yoghurt, cheese, olive oil, other oils/butter, dried fruit, water, processed meat, sweets/snacks, sugar, honey/marmalade and sweet drinks intake. The outcomes of the questionnaire are quality scores of eating habits regarding 11 nutrition aspects: fruit and vegetables, carbohydrates, proteins, milk, oil, water, dried fruit, processed meats, sweets/snacks, sweet drinks, and sugar. The questionnaire is presented with a grid of images (buttons), and the system asks the user about his daily consumption of the 24 food items. The number of button presses on each image indicates the number of consumed portions of the food item presented with the corresponding image/question . For simWhile implementing the FFQ in the LBC application offers a good user experience, it also makes it easy to provide partial responses—the users may answer only the questions they deem important. This is not a problem for the users, as the application is intended for self-monitoring, and they can use it as they see fit, but the quality of the data collected with the application was low. Since the method proposed in this paper is general and can be used on any population without particularly unusual dietary habits, we thus used a higher-quality dataset to develop and test it. The questionnaire in the SiMenu had 104 questions, asking the users about the frequency of consumption of different food items. As the questions included in the LBC application questionnaire are a direct subset of the questions in the SiMenu questionnaire, the transformation of the answers to fit the LBC application questionnaire was very straightforward.FFQ representation using a grid of images to list questions is user-friendly and allows a more interactive way of self-reporting dietary habits. However, although the number of questions is only 24 and the questionnaire is not very extensive, the mobile application screen still seems crowded, slightly overwhelming and challenging to read for some users, especially elderly ones. Therefore, our task was to find a way to reduce the list of questions and use machine learning to predict the quality of achieving goals that the user has activated (decided to follow) from the 11 goals listed in The main idea was to find the subset of questions that would allow the algorithm to highlight more problematic goals from those the user chose to follow . Users usually have better dietary habits regarding some goals than others. For example, a user might have decided to use the application to self-monitor his vegetable, protein and sugar consumption habits. In his meals, he usually includes a portion of vegetables and a portion of fish or meat. He always finishes his lunch and dinner with a dessert. When comparing his quality scores to the optimal amounts of vegetables, protein and sweets, the algorithm will detect that the user eats enough protein and should maybe include more vegetables, but he overeats sugar. We wanted to teach our algorithm to pay more attention to the problematic goals. The most attention should go to sugar consumption, a little less (but still some) attention should go to the goal regarding vegetable intake, and the least attention should go to protein intake (as it is the best). This is included in the algorithm as weights assigned to goals and helps better assess the more problematic goals, which can then be used to give better recommendations or identify the important questions for the user.In this section, we first describe the pipeline used in the experiments. Next, we describe the machine-learning techniques used in the experimental setup. Finally, we describe a function that personalises the questions’ importance by transforming distance to the optimal quality scores for the activated goals into weights. With this, the application can determine the most informative questions based on the user’s previous answers.When reducing the number of questions, we strove to keep half the questions at most and explored options where we tried to predict targets by using 4, 6, 9 or 12 questions. These numbers are chosen based on the mobile application layout . We wantWe conducted three different experiments to reduce the number of questions: (1) the subsets of questions were chosen randomly; (2) we chose the most important questions by calculating their importance as features for predicting nutrition quality scores assuming all activated goals are equally important; (3) we calculated the distance of predicted quality scores’ values from the experiment to optimal quality scores for activated goals only, transformed them to weights, and recalculated feature importance .For the first experiment that was used as a baseline, we decided to choose questions randomly. Another option would be to use one of the dimensionality reduction methods such as Pearson correlation analysis , as usedWe conducted the experiments as multi-target regression problems, which means that several quality scores are predicted simultaneously . In our In the LBC application, users are free to activate (follow) from 1 to 11 goals. Therefore, the case in which the user chooses just one goal can be treated as a single-target problem, and in this case, experiment (3) does not differ from the experiment (2), which was already addressed in our previous work ,15. TherAnswers to the questions are first transformed into a ‘portion per day’ measure. A similar technique is used with the goals. In machine learning, the transformed answers to the questions are called features, and the quality scores are called targets. Both features and targets are then scaled using the min–max normalisation:1.Random features. We choose n random features, n being a number from a set of 2.Statistically optimised features. We choose the best n features, n being a number from a set of sklearn library, feature importance is calculated on each fold and then averaged over the folds. The chosen features are then used to build a model on the train set, and the evaluation of the model is completed on the test set. This experiment considers all of the goals equally important for the user.3.Personalised features. The third experiment is split into two steps. The first step is the same as the second experiment. The second step takes the predicted values from the second experiment and calculates the distance to the optimal values of the goals  or should not be over-reached . We calculate the distance asWe conducted three experiments: random features, statically optimised features, and personalised features. Additionally, we compared cases when we showed 4, 6, 9 or 12 questions on the image grid.There are 2037 combinations of goals in which at least two goals are activated. We present the results averaged by the number of activated goals, which is completed for all cases of selected features. This section presents the main results, and the remaining can be found in In n random equations. The second one uses feature selection to determine n best features (which correspond to questions), n being a number from the set of The LBC application integrates a Food Frequency Questionnaire in a rather innovative way. However, although the questionnaire is reasonably short (24 questions), the representation with the image grid still becomes quite hard to read, especially for elderly users. Therefore, in this paper, we investigated a way to reduce the number of questions. We compared three approaches. Two of them are pretty straightforward. The first one serves as a baseline and simply picks Based on the results in Another conclusion from the experiments is that the prediction error increases with more activated goals. It also decreases with the number of selected features. Based on these conclusions, nine or 12 features or questions would be the most reasonable choice to be implemented in the application.Another observation regarding We conducted our experiments on a dataset derived from a dataset from the SImenu study . While iIn this paper, we proposed a method to reduce the number of questions and FFQ used in the LBC application. The number of questions is reduced based on users’ chosen nutrition goals and how well they achieve them. Additionally, the application should give more attention to the more problematic goals related to nutrition habits requiring the most improvement.random features, statically optimised features and personalised features. We considered cases where the application shows 4, 5, 9 or 12 questions instead of 24. We concluded that the proposed method—personalised features, which considers that goals are not equally essential and considers users’ previous answers, performs the best for the task. In our future work regarding this particular FFQ, we would like to explore further the possibilities of adopting the questionnaire to the users’ preferences based on their answers. We would also like to integrate the proposed method into the existing application and test it in the field on the actual longitudinal data.We compared three methods for choosing the questions in the FFQ—In addition to working with this particular questionnaire, we plan to test the proposed on more complex questionnaires in which questions and goals are more intertwined than in the FFQ used in this paper and on questionnaires where questions are asked more conventionally: question by question. Finally, we would like to explore more options to personalise the questionnaires based on users’ previous answers by using active learning —where th


People with a diagnosis of schizophrenia (PSz) have difficulty engaging in social interaction, but little research has focused on dialogues involving PSz interacting with partners who are unaware of their diagnosis. Using quantitative and qualitative methods on a unique corpus of triadic dialogues of PSz first social encounters, we show that turn-taking is disrupted in dialogues involving a PSz. Specifically, there are on average longer gaps between turns in groups which contain a PSz compared to those which do not, particularly when the speaker switch occurs from one control (C) participant to the other. Furthermore, the expected link between gesture and repair is not present in dialogues with a PSz, particularly for C participants interacting with a PSz. As well as offering some insights into how the presence of a PSz affects an interaction, our results also demonstrate the flexibility of our mechanisms for interaction.This article is part of a discussion meeting issue ‘Face2face: advancing the science of social interaction’. Difficulty engaging in social interaction is one of the most debilitating aspects of the disorder with significant consequences for the lives of those diagnosed. People with a diagnosis of schizophrenia (PSz) have low rates of employment . Social Our understanding of the social difficulties in PSz is derived primarily from studies exploring social cognition in PSz, referring to the mental operations that underpin the process of social interaction such as perception and interpretation of social cues . Such st (a)hesitation particles: ‘uh’ ‘erm’), pauses and self-repairs such as repeated words or phrases or reformulations of the utterance in progress [By contrast to written language, talk in interaction is characterized by incomplete utterances, non-word fillers  account of turn-taking , takes set al.  distinguet al.  emphasizet al. , althouget al. . Additioet al. , and canFor PSz, individual tasks suggest that they have difficulty monitoring their own behaviour  and mismper se. PSz and their interacting partners use fewer hesitation particles than Cs, which may be owing to reduced competition for the floor, an empirical question requiring more in depth analyses of different corpora. For unfilled pauses (defined as gaps of greater than 200 ms between utterances where the same speaker speaks before and after the gap), these are more common within the turns of people interacting with a PSz. We hypothesize that this may be because floor holding and turn yielding cues are less useful in dialogues with a PSz.Studies using a unique corpus of triadic interactions in which half of the dialogues include a person with a diagnosis of PSz, but their interacting partners are not aware of the diagnosis (see §2), show that PSz use fewer gestures while speaking , and havThe triadic nature of the interactions in this corpus offers a unique opportunity to investigate the dynamics of turn exchange when there is competition for the position of speaker/addressee. This is not possible in dyadic interactions, and is more complex in larger multiparty interactions.The findings derived from this corpus to date on disfluencies and gesture ,34,36 ar. 2 (a)The corpus, described elsewhere  consists (b)M = 15.8, s.d. = 6.76; PANSS negative symptoms M = 9.95, s.d. = 3.36; PANSS general M = 28.41, s.d. = 10.42). PSz participants were not displaying overt symptoms at the time of the interactions, e.g. verbally responding to auditory hallucinations.Exclusion criteria included those presenting with motor side effects from anti-psychotic medication (e.g. muscle stiffness and involuntary muscle spasms) and non-fluent English speakers. Seventeen of our PSz participants were taking anti-psychotic medication  and three were medication free. All PSz participants were diagnosed as having PSz and were regularly attending psychiatric outpatient appointments. The positive and negative syndrome scale for schizophrenia (PANSS)  assessed (c)Participants were instructed to discuss a moral dilemma called the Balloon Task. This task  require (d)All speech data were transcribed in ELAN . The durSelf-repairs were annotated using strongly incremental repair detection  which a−1), we imputed the missing data using a linear trajectory, otherwise left the data as missing. Following the methodology in [Hand movement was automatically extracted from the raw motion capture data. In order to control for individual variation, for each participant we extracted the movement from each of the three hand/wrist markers, and calculated the mean and standard deviation (s.d.) of movement in any direction by frame in millimetres (mm). For frames with missing markers, if this was fewer than 50 frames .It should be borne in mind that although we believe that our automatically derived hand movement measures are a good proxy for gesture, they do not distinguish between gestural hand movement and other hand movement . It is also the case that the automatic hand movement annotation captures only the movement phases of a gesture—including preparation and retraction , and wilAnalyses were performed in SPSS 28.. 3 (a)In order to assess differences in turn-taking in the C and PSz dialogues, we compared the duration between each turn by group, participant type and who speaks next.f1,7068 = 8.513, p = 0.004). However, drilling down in the PSz groups suggests that this is not the complete picture. While there is no significant difference in the gap following a turn by the PSz and Cs in the PSz groups, this masks the difference which emerges when we look not only at the identity of the person who speaks the turn prior to the turn change but also the turn following the turn change, as shown in f3,7066 = 3.880, p = 0.009). Post hoc tests with a Bonferonni correction show no significant differences between groups except for between C to C in the control and PSz groups  −137.31 to −13.29). This means that turn exchanges between the two Cs in the PSz group have a longer gap than turn exchanges between Cs in the C group.As seen in These results, particularly in conjunction with the less fine-grained results presented in , provide (b)Alongside previous results on disfluencies, the above quantitative analysis suggests that in PSz interactions there are bigger gaps between turns between the two Cs in interactions including a PSz. But what does this mean in practice? We now turn to some examples from our data. Note that our examples are for illustrative purposes only. We do not claim that our discussion of them is exhaustive and nor do we describe the examples in the level of detail of CA. (i)a, as C3 is asking the question, both the PSz and C1 are looking at C3 as he speaks. C3’s gaze and postural orientation is towards the PSz, which is taken as an indication—at least by C1 who does not immediately proffer an answer to the question—as C3 selecting PSz as the next speaker [figure 2b), following a short gap in which none of the participants alters their posture or shifts their gaze, and no answer is forthcoming from PSz, C3 further specifies his initial question, increasing the expectation of a response. After approximately a second of the 2.39 s gap in line 5, rather than providing an answer, which both C3 and C1 seem to expect, PSz leans back slightly and shifts his gaze towards C1, at which point she takes the floor and provides the second part of the original adjacency pair. The 2.39 s gap in line 5 is over twice as long as the 1 s ‘standard maximum’ silence in dialogue proposed by Jefferson [1The clearest case of the pattern of pauses, which we hypothesize to be more common in the PSz interactions, is that where the PSz is passing up an apparent opportunity to take the floor, which is subsequently taken by the other C participant, after a gap. An example of this can be seen in figure 2 speaker . In lineefferson , and sucefferson . In this (ii)a) the speaker, C2, is actively orienting her body, gaze, head and gestures towards the PSz, with C3, also orienting towards the PSz. The PSz is unresponsive and as C2 begins to articulate the final word of the utterance in line 1–2 (‘thing’) she turns her gaze towards C3, who simultaneously turns her gaze towards C2 and provides an acknowledgement in overlap (figure 3b), line 3, as well as a non-verbal nodding response. This creates an environment in which the agreement or disagreement of the PSz becomes relevant—even without C2’s bodily orientation towards her, which the PSz does not take up in the following 1.81 s long gap. Interestingly, even before C3’s agreement, C2’s utterance in line 1–2 (which is oriented towards the PSz) seems to be looking to elicit agreement from the PSz, as it builds on a recent previous utterance from her; less than 10 s previously the PSz stated ‘I don’t reckon it’s that hard to fly a balloon’.The example sequence in figure 3c), line 4. As in the previous example, this first pair part sets up the expectation for the second part of the adjacency pair. This means that the PSz no longer simply has the opportunity to take a turn, but there is a stronger—socially normative—obligation for her to do so. At the start of the question in line 4, C3 is still gazing at C2, but she turns her gaze towards the PSz over the (1 s) duration of the question, showing that she also orients to the expectation of a response from the PSz [Towards the end of the long gap, C2 turns her gaze back towards the PSz, followed by asking her a direct question c, line 4 the PSz .d,e), turning her gaze back to C2 just after C2 utters ‘older’ in line 6 before finally taking the floor in (f), line 8. As can be seen in this example, the Cs are doing a lot of interactive work to include the PSz in the interaction.Following a 540 ms gap where the expected response is not forthcoming, C2 provides, in line 5, a reason for the question, which demonstrates that she expected the PSz to take a turn. The PSz once again avoids the now more explicit turn-taking cue by actively looking away, precisely as C2 begins the utterance in line 5 ‘you haven’t …’ d,e, turnfloor in f, line 8Taken together, the quantitative results and these examples suggest that there are cases in the PSz interactions where there are differences in turn-taking patterns. This may be because the PSz lacks awareness of the normative turn-taking expectations, or because they are actively avoiding cues directed towards them.We now turn to the relationship between gesture and repair in dialogues with a PSz. (c)As discussed, previous work shows that PSz have decreased gesture use while speaking  and use more while not speaking, while the Cs in the PSz group gesture proportionally less while speaking, as shown in 2 showed a significant main effect of speaking , such that hand movement is much more likely when someone is speaking, a significant main effect of group/condition , such that PSz produce more gesture than their C interlocutors, and a significant interaction effect of group and condition by speaking , with significant differences in the non-speaking condition between the PSz in the PSz group and both Cs in the PSz group (p < 0.01) and Cs in the C group (p = 0.016) and in the speaking condition between the PSz and Cs in the PSz group (p < 0.001). This means that PSz produce more gestures than both C groups when not speaking, and their interacting partner Cs produce fewer gestures than the PSz when speaking.Firstly, we should note that, in contrast to previously reported results based on participant level values and a less sensitive measure of gesture ,35, we df1,7103 = 5.23, p = 0.022), a main effect of number of words  and an interaction between group type and repair .3 This means that there is less hand movement in turns with repair in the PSz group than in the C group, and demonstrates that the main effect of group is driven by the differences in turns which contain repair. There was no main effect of repair .Turning to the relationship between gesture and repair (looking only at the hand movements which co-occur with speech), we can see that the presence of repair in a turn is a good predictor of amount of hand movement, but only in the C groups, as shown in b), with amount of hand movement of a PSz unaffected by the presence or absence or repair. A GLMM with the same settings and factors except with group/condition instead of group showed the same pattern of main and interaction effects.4 Post hoc tests show that in the turns with repair, Cs in the C group use more gesture than Cs in the PSz group , and that Cs in the C group use more gesture in turns with repair  than in turns without repair, in line with previous findings. By contrast, Cs in the PSz group show the opposite pattern, producing less gesture in turns containing repair . We will return to the possible reasons for this in the discussion.Interestingly, when we drill down by participant type, we see that the effect is more pronounced in the Cs in the PSz group b, with a5 we see that the unexpected effect of Cs producing less gesture in turns containing a repair only holds when the PSz is the next speaker .Further, this difference is sensitive to the turn-taking dynamics discussed in §3(a). As shown in . 4This mixed methods analysis provides an in-depth investigation of turn exchange behaviour in triadic interactions involving a person with a diagnosis of PSz. The findings demonstrate that PSz’ turn-taking behaviour deviates from expectations, in often subtle ways, resulting in an adaptation by others. Interactions involving PSz showed reduced competition for the floor, and a lack of clarity about who should take the floor. PSz’ use of floor change cues deviates from C participants’ expectations; missing or avoiding subtle turn exchange cues and failing to provide such cues during their own turns. This difference in response time is also consistent with work which suggests that competition for the floor in multiparty interactions usually reduces turn exchange times —as is thWe hypothesize that the differences seen in the turn-taking behaviours may be because the PSz lacks awareness of the normative turn-taking expectations, or because they are actively avoiding cues directed towards them: our analysis here, based on an automatic detection of silences between turns, does not distinguish between gaps which occur at a TRP and those that do not, which may be a factor here (though note that our broad observations about differences between the groups hold despite this lack of nuance). Future work will address these questions using both human annotation and recently developed automatic methods to detect TRPs , and wilfewer gestures in utterances that included self-repair. Overall, the presence of a person with a diagnosis of PSz in a social interaction changes the behaviour of those they are interacting with, despite their diagnosis being undisclosed.Furthermore, the multimodal coordination between gesture use and self-repair that persists in C interactions, is not present in interactions involving a person with PSz. PSz’ use of gesture was not related to their use of self-repair, while Cs interacting with a PSz displayed Our findings align with those of previous studies of communication in PSz derived from role-play or task-based methodologies, specifically, PSz have difficulty meshing their turns , have de‘gesture’. As such, in the current analysis, we employed a more sensitive measure of hand gesture based on the raw motion capture data of three motion capture markers, rather than one, alongside manual inspection of the data. This analytic approach revealed that, compared to Cs in either group PSz displayed more hand movements categorized as ‘gesture’ when they were not speaking. Observational annotation of these movements would be required to identify their nature, however, one working hypothesis is that these movements are indicative of displacement behaviours, which are self-directed behaviours, found to be correlated with states of heightened arousal, or anxiety . This rfewer hand gestures when speaking. Taken alongside the lack of competition for the floor, this pattern may suggest a reduction in the need to employ floor-holding techniques such as hand gesture. Although this may be the case, drilling further into the turn exchange dynamics we also identified a disruption in the relationship between gesture and speech in both PSz and their C partners, compared to the C group, where we saw the expected relationship between repair and increased gesture use .The most prominent finding is seen in turn exchanges where Cs pass their turn to the PSz; here Cs employed significantly fewer gestures when they have verbal difficulty, as indexed by the use of self-repair. In interactions with a PSz, the relationship between speech repair and gesture is disrupted, not only for PSz but for the interaction as a whole. This suggests that when passing a turn to a PSz, Cs prioritize use of one modality rather than coordinating modalities.This is puzzling. We hypothesize that the use of gesture in turns which contain self-repair is a normally productive strategy, signalling either the presence of a potential problem or the attempt to resolve it. In interactions with a PSz, where turn exchange may have greater ambiguity, this strategy does not seem to be employed. This might suggest that its usefulness is overridden by other considerations in the interaction. Although the current analyses do not identify the reason for this, we present a number of possible explanations. For example, if the potential misunderstanding involves the PSz, which may be more likely in cases where they take the next turn, their diminished responsiveness, potentially even a lack of shared gaze (see the example in The current analysis did not investigate the reasons for the behaviours observed, in either turn-taking or gesture and repair, nor do we suggest that any behavioural pattern is superior to another. This study merely presents an account of how communication in interactions involving PSz differs from those involving Cs. We do not know if the nature of the task, or the fact that it took place in a laboratory environment contributed to a level of anxiety in PSz or how this may have contributed to PSz’ behaviour. Future comparative studies in different contexts, using different conversational topics could explore these questions.. 5These investigations demonstrate the complex interconnectedness of participants in an interaction and the necessity to analyse them as a dynamic unit ,57. As w


Growth differentiation factor 15 (GDF-15) is a highly divergent member of the TGF-β superfamily and has been implicated in various biological functions. However, the expression of GDF-15 in patients with acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is unclear.The study included 47 AE-IPF patients, 61 stable IPF (S-IPF) subjects, and 31 healthy controls (HCs). Serum GDF-15 levels and their expression in the lung were measured. The correlation between serum GDF-15 and other clinical parameters and the risk factors for AE occurrence and the survival of IPF patients were analyzed.Serum GDF-15 levels were significantly elevated in AE-IPF patients (1279.22 ± 540.02 pg/ml) as compared with HCs (891.30 ± 479.90 pg/ml) or S-IPF subjects (107.82 ± 14.21 pg/ml) (both p < 0.001). The protein and mRNA expressions of GDF-15 in the lung of AE-IPF patients were significantly increased as compared with S-IPF cases . The serum GDF-15 level was correlated with the clinical variables of inflammation, metabolism, and disease severity in IPF subjects . The GDF-15 serum concentration was significantly higher in decedents than in survivors (p = 0.005). A serum GDF-15 level above 989.3 pg/ml was a risk factor for AE occurrence (p = 0.04), and the level above 1,075.76 pg/ml was an independent predictor for survival in IPF cases (p = 0.007).The GDF-15 level was significantly elevated in subjects with AE-IPF. GDF-15 could be a promising biomarker for AE occurrence and survival in IPF patients. Idiopathic pulmonary fibrosis (IPF) is the most common and devastating idiopathic interstitial lung disease (ILD), thus resulting in a progressive decline of respiratory function and early mortality . During Growth differentiation factor 15 (GDF-15) is a divergent member of the transforming growth factor-β (TGF-β) superfamily, also named macrophage inhibitory cytokine-1 (MIC-1) . It is uFor patients with AE-IPF, diffuse ground glass opacity (GGO) and consolidation on chest imaging and DAD on histopathology, similar to what is observed in ARDS subjects. However, the expression of GDF-15 in the acute exacerbation of IPF remains unknown. In present study, we aimed to explore the expression and potential role of GDF-15 in a Chinese cohort of AE-IPF subjects.The current study recruited 108 IPF subjects  and 31 healthy controls (HCs) in Nanjing Drum Tower Hospital, Nanjing University Medical School from January 2015 to December 2018. The diagnoses criteria of IPF were based on the updated international practical guideline in 2018 . Lung spThe serum samples were collected, aliquoted, and stored at -80 °C. The date of sample collection was the day following admission . The serum concentrations of GDF-15  and leptin  were measured using enzyme-linked immunosorbent assay (ELISA) kits on the basis of the manufacturer’s instructions. Each sample was assayed in duplicate.Quantitative real-time PCR (RT-PCR) and western blot (WB) were used to detect the mRNA and protein expression of GDF-15 in the lung from IPF patients and HCs as described previously . ImmunohClinical data were collected from electronic medical records. The vital status was determined from medical records or a telephone follow-up. The deadline of the follow-up was November 17, 2019. The duration of survival was from the date of sample collection to the date of death or vital status confirmed. Concurrent infection was defined as patients with clinical symptoms of fever or/and purulent sputum, elevated white blood cell (WBC) counts, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and/or lactate dehydrogenase (LDH), or positive pathogen tests.The scores of gender–age–physiology (GAP) and chest high-resolution computed tomography (HRCT) were used to assess the disease severity of IPF patients. The total GAP score was calculated by the method proposed by Ley et al. . Chest H2) or Fisher exact test, and continuous variables were evaluated by independent sample t-test, Kruskal–Wallis, Mann–Whitney U test, or one-way ANOVA test. The correlations between serum GDF-15 and other clinical variables were assessed by Spearman’s or Pearson’s correlation analysis depending on the distribution of the variables. The survival curves were generated by Kaplan–Meier methods and compared by the log-rank test. The optimal cut-off value for predicting AE occurrence and the mortality was determined by receiver operating characteristic (ROC) curve. Logistic models were used to analyze the risk factors for AE and Cox regression models were built to examine the predictors of time-to-death in IPF patients. p < 0.05 was considered to be statistically significant. Statistical analyses were performed by IBM SPSS version 21  and Prism version 8 .The categorical variables were presented as numbers and percentages, and continuous variables were expressed as the mean ± standard deviation (SD). The comparisons of the differences of categorical parameters were assessed by the chi-square  , forced vital capacity (FVC), carbon monoxide–diffusing capacity (DLCO), GAP scores, and stages were significantly worse in the AE-IPF group compared with the counters   was significantly elevated compared with S-IPF subjects (891.30 ± 479.90 pg/ml) or HCs (107.82 ± 14.21 pg/ml)   (5 fields each sample).The protein and mRNA expressions of GDF-15 in the lung of AE-IPF subjects were increased significantly compared with HCs and S-IPF cases by WB and RT-PCR  .As shown in The areas under the ROC curves of serum GDF-15 levels were statistically significant in the classification of AE-IPF (n = 47) or S-IPF patients (n = 61)    of AE-IPF patients were significantly worse than S-IPF cases. The duration in the hospital of AE-IPF cases was significantly longer  and in-hospital mortality was significantly greater than S-IPF subjects   were significantly different between patients with S-IPF and AE-IPF. The published data showed that poor pulmonary physiological function, mechanical procedures, and pulmonary hypertension were associated with AE-IPF –exposed mice, and increased GDF-15 expression may contribute to CS-induced pulmonary inflammation . GDF-15 The circulating GDF-15 levels have a close correlation with known markers of fibrosis such as type I collagen and osteopontin . GDF-15 The present study has some limitations. First, the sample was small and all patients were from the same center. We have no data of serum GDF-15 concentrations from the same patient in different clinical conditions , which would be helpful to further support the utility of GDF-15 as a biomarker of IPF. A prospective and multicenter study of a larger sample cohort would be beneficial to provide additional evidence on GDF-15.In summary, the expressions of GDF-15 were increased significantly in patients with AE-IPF. An elevated serum GDF-15 level was associated with infection and inflammation, metabolism indicators, and the disease severity of IPF and could predict AE occurrence and the survival in IPF subjects.The authors would like to thank all patients for sending their consents. This work has been presented in the form of one late-breaking abstract at the European Respiratory Society Congress 2019 in Madrid.The original contributions presented in the study are included in the article/The studies involving human participants were reviewed and approved by Ethics Committee of Nanjing Drum Tower Hospital. The patients/participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.MC and LS conceived and prepared the manuscript. MC, LS, LinG, ML, YuZ, and LilG contributed to the collection of clinical data, statistics, and experiments. FM and MC evaluated the histopathology. FM and JZ provided the lung tissue sample. MC, XQ, XG, MM, YT, XL, and YX contributed to the administration to the patients. LS, MC, FM, and YX reviewed the manuscript and took responsibility for the integrity and accuracy of data analysis. All authors reviewed and approved the final draft.This study was partly supported by National Natural Science Foundation of China .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Single/multilayer graphene holds great promise in withstanding impact/penetration as ideal protective material. In this work, dynamic penetration behaviors of graphene has been explored using molecular dynamics simulations. The crashworthiness performance of graphene is contingent upon the number of layers and impact velocity. The variables including residual velocity and kinetic energy loss under different layers or different impact velocities have been monitored during the hypervelocity impact. Results show that there exists deviation from the continuum Recht–Ipson and Rosenberg–Dekel models, but these models tend to hold to reasonably predict the ballistic limit velocity of graphene with increasing layers. Besides, fractal theory has been introduced here and proven valid to quantitatively describe the fracture morphology. Furthermore, Forrestal–Warren rigid body model II still can well estimate the depth of penetration of multilayer graphene under a certain range of velocity impact. Finally, one modified model has been proposed to correlate the specific penetration energy with the number of layer and impact velocity. Especially, its inherent strength exceeding 100 GPa, Young’s modulus as high as 1 TPa16 and low density of 2.2 g/cm3 make multi-layer graphene (MLG) an extraordinary armor material exhibiting excellent impact energy delocalization under a supersonic penetration event and hold great promise in the field of safety protection for lightweight body armor design17 and spacecraft protection18. So far, most of experimental tests are restricted to the quasi-static mechanical properties of graphene except the recent supersonic projectile penetration carried out by Lee et al.19 in 2014, in which the high-strain-rate behavior of multilayer graphene by using miniaturized ballistic tests has been investigated. It has been discovered that the specific penetration energy for multilayer graphene is about 10 times more than literature values for macroscopic steel sheets19. Such extraordinary findings have aroused great interests in the application of graphene into the field of impact protection.Because of the excellent properties, such as exceptionally high intrinsic strength and stiffness arising from the two-dimensional (2D) hexagonal lattice of covalently bonded carbon atoms20 has its unique advantages, which can be used to simulate hundreds of thousands or even millions of atoms by virtue of universally applicable force field relations. Therefore, MD simulation have provided much convenience and feasibility to understand the dynamic behaviors of 2D materials26. As a major two-dimensional material, there are lots of MD studies on graphene’s properties, especially its impact resistance. In terms of axial wave and cone wave propagation. Briefly, the failure mechanism of single-layer graphene under high-speed impact of diamond projectiles was explored by Xia et al.24 and found that the circular shape graphene possesses the best impact resistance for similar sample size. Furthermore, Bizao et al.27 simulated the process of 1–3 layers of graphene being subjected to the impact by 3.5–7.5 km/s of fullerene, evidencing the angle law of graphene crack observed from Lee’s experiment. It has been concluded that the high axial-wave and cone-wave velocity favor the momentum transfer and improvement of ballistic protection performance of graphene23. Meng et al.22 further explored the regularity of cone wave propagation relating to the boundary conditions and propose one approach to estimate the critical graphene membrane size, which offers theoretical guidance for the size engineering of graphene as a protective material. In addition, Bizao et al.21 put forward the law of scale effect to explain the discrepancy by one order of magnitude between experiments and MD simulations and correlate the specific penetration energy with the number of layers. In addition to graphene, other 2D material such as BC3and C3N whose structures is similar to graphene’s have also been explored by researchers using MD simulation30. Sadeghzadeh et al. explored the ballistic properties of C3N and BC3 nanosheets against hypersonic bullets with numbers greater than 6. The critical perforation conditions, and thus, the intrinsic impact strength of these 2D materials were determined by simulating ballistic curves of C3N and BC3 monolayers30. The mechanical properties of defective hybrid C3N–BC and defect-free hybrid C3N–BC3 also have been investigated. Results show that the effect of these flaws on Young’s modulus is less than their effect on failure stress and strain29. Further work has been performed to explore the mechanical and ballistic properties of Aluminum nanocomposites reinforced with monolayer polyaniline (C3N) and it is found that the nanocomposite can absorb 35% energy of nanoparticle when C3N was placed on the top of the aluminum surface28.Confronted with experimental challenges, it is experimentally harsh to directly perform hypervelocity impact. As an alternative approach to physical experiments, molecular dynamics (MD) simulation31, however, the inherent correlation between ballistic limit velocity and the number of layers of graphene are largely unknown. Is there a suitable way to predict the ballistic limit velocity of graphene at different layers? Are the continuum models related to penetration mechanics such as Recht–Ipson model32 still applicable at the ultra-small nanoscale? These need to be explored further. The description of the morphology of damaged graphene is usually qualitative and herein we make an effort to quantitatively to explain the morphology of the membrane after failure. What’s more, the residual velocity, kinetic energy consumption, impact displacement, total impact contact time and penetration depth in our work will be also discussed.As we see, much progress has been made on the impact resistance of graphene and other 2D materials, nonetheless unresolved issues but of scientific importance remain unclear. The ballistic limit velocity is one of the important indicators signifying the material’s capability of impact resistance. Sadeghzadeh and Meng both found the result that the ballistic limit velocity increase with the increased number of grapheneV0 ranging from 2500 to 7000 m/s. The residual velocity Vr, the kinetic energy loss ΔEK, i.e., V0, as discussed from Fig. Vbl. The kinetic energy loss ΔEk first increases with increasing the initial impact velocity to a peak value at around the ballistic limit velocity, followed by a drop and subsequent hike again as shown in Fig. In this part, the single or multi-layer graphene is subjected to the impact of the diamond nanosphere of 6.0 nm in diameter, acting as projectile, with an initial velocity mentclass2pt{minimmentclass2pt{minimThe simulation snapshots of projectile collided with the single layer graphene membrane at different initial impact velocities of 2000, 2750 and 3500 m/s are shown in Fig. Vr and ΔEk present complicated and non-linear trends. The whole region can be roughly divided into three parts: Region A, B and C. To begin with Region A, the bounce-back, i.e., ricochet region, in which the initial velocity is comparably small, the projectile fails to perforate graphene and is bounced back without exerting damage to the graphene membrane. Under this circumstance, the membrane maintains a relatively good elastic deformation as shown in Fig. As the initial impact velocity rises from 2 to 7 km/s, the corresponding results of both 32, the initial impact velocity V0, residual velocity and ballistic limit follow are correlated as follows,p, mp are the mass of projectile and the mass of plug ejected by projectile, respectively. When satisfying Mp ≫ mp, the above equation can be reduced toBallistic limit velocity is one of the important parameters in describing the anti-penetration capability of structures or materials. According to Recht–Ipson modelIn order to test the validity of the continuum model, a series of MD simulation have been performed by varying the initial impact velocity. Especially, a velocity increment of 10 m/s in the transitional region B is employed to accurately estimate the ballistic limit velocity. The theoretical predictions of ballistic limit velocity from the Recht–Ipson model for single layer to four layers are obtained by fitting the residual velocity to the Eq. , highligVbl for single, double, triple and quadruple layer graphene are separately measured using the Recht–Ipson model and MD simulations and listed in Table Vbl for nano-impact thin target, especially for larger thickness target.As observed from Fig. 33, which employs the conception of effective resisting stress that simplifies complex penetration process, taking the form ofp, H, σr are the density of projectile, the target thickness and effective resisting stress, respectively. leff is effective length of projectile obtained based on the principle of equivalent to a cylinder with equal cross-sectional area and mass.Although the governing equation from Recht–Ipson model is simple and easy to use, nonetheless it is not associated with materials properties of the projectile and the target and lacks significant physical meaning. In order to further explore the ballistic limit velocity, we refer to the Rosenberg–Dekel model34 MD, the ratio of σr and Yt is related to the thickness of the target plate (H) and the diameter of the projectile (here D = 6 nm), Yt is the strength of material. For the thin target (H/D < 1/3), there is:According to the empirical formula provided by Rosenberg and Dekel35. Normally, the maximum resisting force can be readily obtained by calculating the interaction forces between the projectile and target from the MD simulations. As for the corresponding contact area, it can be achieved with the aid of Materials Studio software, the corresponding surface area corresponding to the maximum resisting force can be calculated following the previous approach36, then the maximum impact stress is obtained. As per Eq. . The orange high stress area presents a hexagonal shape at 4.649 ps while the red central part represents higher stress caused by the compression between the membrane and the projectile. Interestingly, the border of the hexagon is the deformation bulge part of the membrane, which is just like a barrier converging stress waves to interact with each other within it. Subsequently, the hexagon area where shearing stress converges gradually shrinks to the size similar to the impact area until the strongest stress concentration appears at times of 6.249 and 6.749 ps. This can be vividly confirmed from the greatest resistance force exerting on the projectile by the graphene membrane as shown in Fig. 22.In order to demonstrate internal wave propagation and reveal the underlying mechanism of the failure of single layer graphene at 2750 m/s, shear stress distribution has been monitored at different simulation times. As observed from Fig. 27.It is of scientific importance to investigate the morphology of hole left in the graphene membrane after penetration and also the corresponding mass loss. In view of the irregularity of the holes after destruction, the shape factor in the fractal theory  model40 are widely used in describing the penetration depth.Depth of penetration (DOP) is an important indicator of impact resistance, therefore it becomes necessary to accurately estimate this parameter using MD simulations and test the validity of the continuum penetration depth models of rigid projectile at the atomic/nanoscale. For rigid projectile, Forrestal–Warren (F–W) modelP, L, ρP and ρt are the penetration depth, effective length of projectile, densities of projectile and target, respectively; σyt is the quasi-static yield strength of target, ψ = 0.5 for the hemispherical nosed projectile and thus the projectile nose coefficient N* = 0.5. L, ρP, ρt and σyt are 4 nm, 3.5 g/cm3, 2.2 g/cm3, 130 GPa, respectively.ρP and σyt have the same meanings and values as them in F–W model I.F–W Model II is the first-order Taylor expansion of F–W Model I, which is equivalent to the upper limit of the F–W model. Parameter t in Eq.  is smallt in Eq.  can be rEt, σft are the elastic modulus and flow stress of the target, which are 1 TPa and 140 GPa, respectively, for the graphene.41. Besides, the total impact displacement, which is the distance of the projectile travelling from the initial contact point in the approach process to the final contact point at the instant of initiated restitution where the kinetic energy becomes zero or perforation along the Z-axis. Correspondingly, the total time of impact is the time interval from the instant of the initial contact to that of the final contact between the projectile and graphene. These two parameters have also been monitored as shown in Fig. Since these theoretical models require that the shape of the projectile should be hemispherical nosed projectile. As per the principle of equal cross-sectional area and mass, the 6 nm rigid spherical projectile is equivalent to one hemispherical nosed projectile with a length of 2.0 nm and radius of 3.0 nm, as shown in Fig. 19 proposed the following relationship as per their experimental results,19. This has been discovered by Rafael’s research21 and the value of 21 and basically consistent with the results of Haque27. For instance, at impact velocity of 4500 and 5000 m/s, Haque accordingly obtained the 43.Lee et al.N, V0 to the ballistic limit velocity Vbl; NC, N’C, A, B are the coefficients as obtained from the best fitting.Although scale law has been put forward in terms of number of layer in Rafael’s research, nonetheless the influencing factor of impact velocity has not been properly considered. In order to further accurately predict 19 have been re-drawn and incorporated along with the simulated data for the fitting as displayed in Fig. NC, N’C, A, B are 6385, 25.89, 322, − 2, respectively. Then Eq. 46. The projectile is made of diamond nanosphere with a diameter of 6 nm, which is built by cutting from the diamond structured diamond with the lattice constant of 0.357 nm bulk using LAMMPS. The mass of the projectile containing 19,889 carbon atoms is 2.01 × 10–22 kg. Single layer, double-layer, triple-layer and quadruple-layer graphene are built using Visual Molecular Dynamics (VMD)47 with a dimension of 40 nm × 40 nm in x, y axes, respectively. The adaptive intermolecular reactive empirical bonder order (AIREBO) potential was adopted herein since it has been proved valid to describe the interaction between C–C and C–H atoms49 and reproduce the mechanical properties of carbon systems such as graphene27. But it is suitable for describing the system containing graphene and diamond. Therefore, for the interaction between graphene and diamond, we refer to previous studies and set the LJ parameter separately to describe the interaction between graphene and diamond37. Because, although both graphene and diamond are composed of carbon atoms, their atomic arrangement and structure are completely different. Besides, because of the high Young’s modulus of diamond and for the sake of comparison with the “rigid” assumption inherent in continuum model, the treatment of diamond projectiles as rigid bodies in the nano-scale impact process has also been adopted herein and elsewhere53. The effect of rigid assumption has been evaluated as shown by Figs. 54. The projectile is regarded as a rigid body24 The interaction between graphene and projectile is described by the 12-6 Lennard Jones (LJ) potential and the values of εLJ, σLJ are 0.035 eV and 3.46 Å55, respectively. Note that the boundary of graphene is fixed while the central circular area of 15.0 nm in radius is unconstrained. Since graphene is a two-dimensional and thin material, the entire graphene sheet will move at high speed when subjected to the collision with the projectile. In this case, it is difficult to further study the impact resistance of graphene. Thus, one feasible but carefully corroborated approach of fixed boundary has been adopted herein and the detailed validation process can refer to the Supplementary Information. The projectile is perpendicularly located about 10 nm apart from the center of the graphene membrane. An initial impact velocity ranging from 2000 to 7000 m/s was applied to projectile and the whole impact process is simulated using NVE ensemble with a time step of 0.5 fs43.In this paper, the MD simulation processes are performed using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)40, and the corresponding continuum theories are also different. Our paper mainly is associated with the rigid penetration, with a focus on the impact of “rigid” projectile with the graphene. The effect of “non-rigid” projectile and influence of “free” or “fixed” boundary conditions have also been provided in the Supplementary Information. The setting of “free” or “fixed” boundary conditions will affect the shockwave reflecting, but has little influence on the main conclusion regarding the penetration behaviors of multilayer graphene in this work.Note that penetration can be classified into rigid penetration, deformation penetration and eroding penetrationSupplementary Information.


Drosophila melanogaster that are known to detect humidity, but it is not seen in other coeloconic neurons that are not sensitive to humidity. Dipteran mosquitoes Aedes aegypti and Anopheles gambiae oviposit in water, and the addition of the humidity-inhibiting odorants in a two-choice oviposition assay significantly reduces oviposition. Our results demonstrate that a naturally occurring volatile compound can effectively “mask” detection of an important environmental cue and modify behavior of important vectors of plant and human disease pathogens. Odorants targeting the conserved humidity sensing system of insects, therefore, offer a novel strategy for modifying their behavior.Insects house humidity-sensing neurons in the antenna, which is presumed to be important for a variety of behaviors and survival since water is a crucial component of the environment. Here we use the simple olfactory system of the Asian Citrus Psyllid (ACP), a citrus pest that transmits a deadly bacterium, to identify volatile amines that significantly inhibited humidity-induced activation of antennal neurons. The inhibition of action potentials is observed by single sensillum recordings and mixing these odorants with humid air abolished the humidity avoidance behavior of ACP. The inhibition is conserved in the humidity-sensing coeloconic neurons of dipteran  In addition to acting as a simple cue for detecting water sources, especially critical for small insects prone to desiccation due to large surface area-to-volume ratios7, humidity serves a diverse range of functions across many species of insects. Foraging hawkmoths use humidity as a means of assessing nectar availability in flowers8, and ladybird beetles rely on a range of humidity for tarsal adhesion9.Humidity represents an important sensory modality for many animal speciesDiaphorina citri, commonly known as the Asian Citrus Psyllid (ACP), is native to China but has spread invasively in North America. The ACP feeds, oviposits, and mates on citrus plants10, transmitting to them a bacterial phytopathogen that causes Huanglongbing, and incurable disease of economic significance worldwide11. Similarly, the female mosquito, which transmits pathogens that cause millions of disease-related deaths each year, uses humidity in host-seeking behavior14 and as an oviposition cue2. To detect hosts, mosquitoes often rely on complex blends of odorants and CO2, the components of which act synergistically by potentiating several attractive olfactory neurons15.Of particular interest is the role that humidity plays in the behavior of economically important insects, such as vectors of human or agricultural disease-causing pathogens. 16. In the vinegar fly D. melanogaster, hygroreceptor neurons are housed in specific coeloconic sensilla17 as well as in sensilla located in the sacculus19. In the mosquito Aedes aegypti, an antenna basiconic sensilla detects subtle changes in humidity concentration as well as respond to ammonia and acetone20. Similar responses are also observed in the vinegar fly D. melanogaster to ammonia and a couple of amines by humidity sensing neurons17.In insects, hygroreceptor neurons are usually housed in specific sensilla that contain one of three types of sensory cell: moist-, dry air-, and cold-receptor neurons, yet combinations of chemo- and hygroreceptor neurons housed in the same sensillum have also been described21, such as ACP and mosquitoes. The importance of humidity in insect behavior raises the interesting possibility of using “masking” compounds that can block activation of the insect neurons mediating humidity-detection.In this study, we investigate the presence of hygroreceptor neurons in the ACP, and the ability of specific chemical volatiles to inhibit water vapor-mediated activation of such neurons in ACP and vinegar flies. We also investigated the potential of chemical volatiles that block the detection of a common environmental cue, such as humidity, and modify humidity-driven behavior of species that shared a common ancestral over 350 million years ago23. Each of the four RP sensilla contain three olfactory neurons each, the activities of which have been tested with Single Sensillum Recordings (SSR) against > 100 odorants diluted in paraffin oil as solvent25. In the present study, we found that water vapor alone increased the activity of at least one neuron in the RP4 and RP6 sensilla, but not of neurons of the RP2 and RP7 sensilla  sensilla: RP2, 4, 6, and 7ity Fig. .Figure 126, we turned to the well-characterized D. melanogaster olfactory system. Antennal olfactory neurons in Drosophila that are present in the pit-like sacculus as well as some in the surface coeloconic sensilla have been shown to respond to varying levels of humidity in air and express members of the Ionotropic receptor family27. Amongst them the antennal coeloconic sensilla ac1 is sensitive to humidity and are accessible to sensitive SSR recordings17. The ac1 neurons express members of the ionotropic receptor family19, and while they have not been tested for behavioral response to humidity, they show robust electrophysiological response to humidity17. We performed SSRs in the ac1 sensillum while it was exposed to varying concentrations of hexylamine in both humidified and dry air backgrounds. While water alone induced a robust increase in ac1 activity  specific to their living environment, which ranges from 85% RH in humid rainforests to 20% in dry desert32. In the model system D. melanogaster, some basiconic and coeloconic sensilla on the antennal surface, detect dry air and humidity, and respectively express TRP channels nanchung and water witch32. Additionally, the sensilla of the pit-like antennal structure called the sacculus express members of the Ionotropic receptor family, Ir64a and Ir40a, which are required for sensing of humid and dry air, respectively, when associated with the co-receptor Ir25a and the receptor Ir93a19. These receptors are conserved over hundreds of million years33, giving support to the possibility that the homologs of such receptors mediate humidity detection in different insect species. Additionally, the Odorant-binding Protein Obp59a is also thought to play a part in humidity sensing27.Various protein receptors have been proposed to explain humidity (and dryness) sensing16. Amines might also directly interact with humidity receptors expressed on the dendrites of neurons such as IRs, nanchung and water witch. It has also been reported that insects can express more than one receptor type per neuron34, including Ionotropic receptors tuned to amines35.Using electrophysiology we have identified volatile amines that suppress humidity evoked responses. While the mechanism underlying inhibition is not known, we show that in both species tested, they block humidity-mediated behaviors effectively. In ACP pentylamine reduces the humidity-mediated avoidance, while in mosquitoes it blocks the humidity-mediated attraction to an oviposition site. The mechanism of inhibition may be complex. Ammonia and amines can modify the chemical properties of the air humidity or the temperature of the cuticular surfaceAedes and Anopheles mosquitoes.Future studies will shed light upon the mechanism of action of such amines in hygroreceptor neurons housed in different sensilla. Overall, our results indicate that inhibition of the humidity-sensing pathways with specific amines like pentylamine can lead to oviposition deterrence for Bergera koenegii) and one citrus (Citrus volkameriana) plant (10–15 cm high). Cages were kept at 25 ± 1 °C and 45% relative humidity. Wild type D. melanogaster used in the experiments were of the Canton-S strain and reared on standard cornmeal–dextrose media at 22–25 °C. The M form of A. gambiae  and A. aegypti (Orlando strain) were maintained in a 12:12 (Light:Dark) photocycle at 27 °C and 70% RH.All ACP experiments were performed inside the Quarantine facility at the University of California, Riverside. ACP (Texas strain) was reared in 40 × 40 × 40 cm cages containing three curry  with ACP specimens at 4–7 days old and previously starved for 5 h in a humid chamber. Either 100 µL of water alone or odor in water was applied onto a filter paper (Whatman Grade 2) that had been folded onto itself to fit into a glass tubbing. The latter was connected to either side of the Y-shape glass olfactometer. In the assays delivering humidity on one of the arms (or both) of the Y-tube, the filter papers were treated with water or odor in water, which resulted in about 60–70% relative humidity as input in each arm of the olfactometer, as measured before each trial with a handheld hygrometer (Extech EA20 EasyView Hygro-Thermometer). In the trials where dry air was flown in one of the arms (or both) of the Y-tube, a cartridge of silica gel was added in front of the filter paper, reducing the input humidity in the arm to 15–20% even when odor in water was applied onto the filter paper. Each behavioral trial was performed for 10 min at a 55 mL/minute flow rate of charcoal-filtered air. Each treatment was repeated between 5 and 12 times, and the control and treatment arms were alternated between replicates. Replicates displaying less than 30% participation were discarded. At the end of each trial, the number of animals in the control arm, the test arm, and the entry port (ie: non-participants) were counted. Any trial with a participation rate of less than 30% was not included in the analysis.Oviposition behavior was carried out in bugdorm style (30 × 30 × 30 cm) mosquito cages under 14–10 light cycle, 60% relative humidity, and at 27 °C. Six to seven days after blood feeding, fifteen female mosquitoes were transferred to each bugdorm where two oviposition sites (plastic petri dishes 50 mm) were placed at opposite sides of the cage. The positions of odor-treated and control petri dishes were alternated in the different experimental replicates. In non-contact assays, a glass vial  containing 1 mL of either the odor solution or water was placed onto each petri dish, which were filled with 13 mL of autoclaved tap water. A little cup containing sugar solution wicked through a cotton plug was placed between the petri dishes. The experiments were carried out for 24 h. The egg-containing water was drained through Kimwipe tissues and counted under a scope with the help of a cell counting device. The number of eggs found in each oviposition chamber was counted at the end of the experiment.24.Odorants used in this study were obtained from Sigma-Aldrich at the highest purity available as described previously24 with minor modifications from male ACP (4–7 days old). The odor panel was tested against each type of the four rhinarial plates. Fifty μL of water or odors diluted in water at indicated concentrations were loaded onto cotton wool inserted into Pasteur pipette odor cartridges and used for no more than 4 stimuli each. Odor vapors were delivered from the odor cartridge using a Syntech-55 stimulus controller and diluted approximately three-fold by injecting into a carrier air stream positioned towards the ACP antenna. The baseline activity from one second before the stimulus onset was subtracted from the total activity to obtain a net increase in spikes.Single-sensillum recording was performed as previously describedD. melanogaster) were tested at 3–7 days post-eclosion. Individual flies were inserted into a 1.0 mL pipette tip and secured with molding clay. A glass cover slip was placed underneath the head and a glass pipette was used as a rod to secure an antenna in place. A reference electrode filled with SLR solution was inserted into the eye. Hexylamine was dissolved in paraffin oil to the designated dilutions. A 3 × 35 mm filter paper strip was placed in each 5¾” glass Pasteur pipette to form odor cartridges. Cartridges were allowed to sit and volatilize for 15 min before use. Each cartridge was used no more than twice before being discarded. In the humidified setup, a glass tube was used to maintain a humidified airstream of 10 mL/sec on the preparation, provided by a gas tank routed through a water-filled beaker. The beaker was empty in the dry setup. The odor cartridge was inserted into the side of a glass tube through an opening 130 mm distant from the end of the tube. The end of the tube was placed 5 mm away from the specimen’s antennae, for a total of 135 mm separating the preparation from the point in which odors entered the airstream.Adult male flies —(# in control arm)) /  and were ARCSINE transformed for statistical analysis. Statistical comparisons of behavior data were corrected for multiple comparisons with the two stage set up method of Benjamini, Krieger, and Yekutieli and a desired false discovered rate of 0.05.Supplementary Information 1.Supplementary Information 2.


A long-range surface plasmon polariton (SPP) waveguide, composed of double-layer graphene, can be pivotal in transferring and handling mid-infrared electromagnetic waves. However, one of the key challenges for this type of waveguide is how to excite the SPP modes through an incident light beam. In this study, our proposed design of a novel grating, consisting of a graphene-based cylindrical long-range SPP waveguide array, successfully addresses this issue using finite-difference time-domain simulations. The results show that two types of symmetric coupling modes (SCMs) are excited through a normal incident light. The transmission characteristics of the two SCMs can be manipulated by changing the interaction of the double-layer gratings of graphene as well as by varying various parameters of the device. Similarly, four SCMs can be excited and controlled by an oblique incident light because this light source is equivalent to two orthogonal beams of light. Furthermore, this grating can be utilized in the fabrication of mid-infrared optical devices, such as filters and refractive index sensors. This grating, with double-layer graphene arrays, has the potential to excite and manipulate the mid-infrared electromagnetic waves in future photonic integrated circuits. Surface plasmon polaritons (SPPs) , which aGraphene , a typicRecently, we investigated an intriguing type of graphene-based long-range SPP (LRSPP) waveguide ,33, thatSiR and tSiO2, respectively. To fabricate such a grating, one of the key challenges is how to obtain a feasible manufacturing technique for the cylindrical LRSPP waveguide. Li et al. , where e is the electron charge, fE is the Fermi energy, and τ is the electron relaxation time. The latter is calculated from the relation τ = fμE/(Fev2), where μ is the electron mobility, and Fv = 10−6 ms−1 is the Fermi velocity. In this paper, unless stated otherwise, the following values of different parameters are used: μ = 1.0 m2/(Vs), fE = 0.8 eV, T = 300 K, and d = 1 nm.A schematic diagram of the proposed grating, which is comprised of a graphene LRSPP waveguide array placed on a substrate, is shown in i et al.  have repi et al. ,36 have i et al. . For simg/(ε0ωd) ,39, wher formula ,40, σg ixy-plane. The simulation region was truncated by periodic boundaries in the x-direction and perfectly matched layer boundaries in the y-direction. The mesh sizes were set as 0.1 nm along the x, y axes inside the grating unit, and gradually increased outside the grating unit.In this study, we employed the commercial software of the Lumerical FDTD Solutions to investigate the features of the proposed grating. The two-dimensional simulation was performed for a single unit of the grating in θ = 0°) was projected onto the graphene LRSPP waveguide array along the negative y-direction. θ represents the angle between the direction of y-direction, in which k0 = 2π/λ0 is the k-vector of the incident light, gratingk is the compensatory k-vector by the grating, sppk is the k-vector of the excited SPP mode, and m is the diffraction order. Due to sppk = rkn0, the Equation (1) can be expressed approximatively asrn is the real part of the effective refractive index of the excited SPP mode. However, as the graphene LRSPP waveguide has two graphene layers, our proposed grating is equivalent to two optical gratings. The first grating consists of the inner layer graphene array and the silicon nanowire array, whereas the second grating consists of the outer layer graphene array, the silica layer array, and the silicon nanowire array. For simplicity, the first and the second gratings are referred to as the inner and the outer gratings, respectively. Either of them can individually excite SPP resonant modes. However, according to Equation (2), their corresponding resonant wavelength is different for the same incident light, because the SPP mode excited by two gratings has a different rn value.First, a normal incident plane wave  and the result described in , gσ can be expressed as gσ = grσ + giiσ, where grσ and giσ are the real and imaginary parts of the graphene conductivity, respectively. According to Maxwell’s equations, we can obtainJP, can be derived asE0 is the amplitude of the electric field. Therefore, the optical loss in graphene is determined by the real part of the graphene conductivity, which is related to both the Fermi energy and the electron mobility. On the other hand, we can obtain the optical loss according to the equation L[dB/μm] = 8.86 ikn0 , where εAVG = (inε + outε)/2 is the average dielectric constant of the graphene layers, and inε and outε are the dielectric constant values of the inner and outer layers of graphene, respectively. We observed a similar physical mechanism and phenomena in this study. The resonant wavelengths of the two modes exhibit a red shift with increasing n1 , which is defined as S = Δλ/Δn, where Δλ/Δn is expressed in nanometers per refractive index unit (nm/RIU). The S values of the Sx1 and Sx′1 modes are 2407.9 nm/RIU and 837.1 nm/RIU at n1 = 3.445, respectively. The other assessment factor is the figure of merit (FOM) [S to the full width at half maximum (FWHM) of the transmission peak . The damping of the quadrupole oscillations increases with increasing n3, which results in an increase in the corresponding FWHM. Therefore, the FOM values of the two modes decrease with increasing n3  ,47, whicasing n3 d. Nevertr sensor  in this n2. This can be explained as follows. A strong EM field gathers in the interface between the waveguide and the substrate , the resonant wavelength λ0 can be expressed as λ0 = rP/mn for a normal incident light (θ = 0°). Thus, the values of rn and λ0 increase with n2. On the other hand, exciting the high order SPP mode becomes easier in the case of increasing n2. The Sx′2 mode is effectively excited as n2 = 3.455 , and n1 = 1.72. Consequently, we observed a transmission spectrum with two low-order modes (Sx1 and Sx′1 modes) and five high-order modes   a. The |Eθ ≠ 0° (resλ, can be expressed asFinally, we investigate the transmission characteristics of the grating through an oblique incident light of θ ≠ 0° b. Usuallrn values are much larger than one for the graphene SPP modes, the resonant wavelengths are almost unrelated to θ. resλ values are almost unchanged with varying θ. However, the notch depth of the transmission spectra is sensitive to θ. This can be explained as follows. The electric field of an oblique incident light can be divided into the two polarization components of xE and yE. This results in two types of SPP oscillations along the x-axis and the y-axis, respectively. Therefore, four 1-order SCMs can be excited through two graphene gratings, as shown in x1, Sx′1, and Sy1, Sy′1 modes originate from the SPP oscillations along the x-axis and the y-axis, respectively. The |E| and |H| distributions of the Sy1, Sy′1 modes are shown in θ, the xE component decreases, while the yE component increases. The SPP oscillations will be weakened and enhanced along the x-axis and the y-axis, respectively. Thus, the notch depths of the transmission spectra of the Sx1 and Sx′1 modes decrease, while those of the Sy1 and Sy′1 modes increase, as shown in θ, when λ0 is greatly different from resλ, such as λ0 = 9.0 μm. However, the transmission values of the angular mode exhibit a significant change with θ when λ0 is close to resλ, such as λ0 = 8.5 μm and λ0 = 9.5 μm (θ.Since the = 9.5 μm b. On theIn summary, we have proposed and investigated a novel design for a grating, which is composed of a graphene-based cylindrical LRSPP waveguide array. The numerical simulation results demonstrate that two types of SCMs can be excited by a normal incident light passing through this grating, because such a device with double-layer graphene arrays can be equated to two interacting graphene gratings. Therefore, the excited SCMs can be effectively controlled not only by varying the geometrical and physical parameters of the device, but also by changing the interaction between the two graphene gratings. Furthermore, four types of SCMs can be excited by an oblique incident light, which can be divided into two orthogonal beams of light. Based on the transmission features of the SCMs through this grating, several active optical devices, such as filters and refractive index sensors, can be designed. This grating device with double-layer graphene has the potential to excite and manipulate the mid-infrared waves in future photonic integrated circuits.


Recently, owing to the rich chemistry of fluorographene, new avenues have opened toward graphene derivatives with selective, spacer-free, and dense functionalization, acting as in-plane or out-of-plane metal coordination ligands. The particular structural features give rise to intriguing phenomena occurring between the coordinated metals and the graphene backbone. These include redox processes, charge transfer, emergence, and stabilization of rare or otherwise unstable metal valence states, as well as metal–support and metal–metal synergism. The vast potential of such systems has been demonstrated as enzyme mimics for cooperative mixed-valence SACs, ethanol fuel cells, and CO Single-atom catalysts (SACs) based on graphene derivatives are an emerging and growing class of materials functioning as two-dimensional (2D) metal-coordination scaffolds with intriguing properties. The main drawback of heterogeneous catalysts is that only a small fraction of active centers is accessible for a catalyzed reaction.2 In order to tackle this disadvantage, single-atom catalysts (SACs) are being developed which have active sites consisting of single metal atoms immobilized on a support.3,4 Therefore, SACs exhibit ultimate atom utilization efficiency while being easily recyclable.2,3 Utilizing SACs for the production of technologically and commercially valuable products will ultimately reduce their cost and, most importantly, will help save natural resources of precious metals.5,6Today, 80% of all commercially available chemical products require catalysts in some stage of their manufacture.1,7–10 Carbon-based nanomaterials are particularly attractive because they are lightweight and composed of abundant and non-toxic elements, and offer high surface area and conductivity.11 Recently, 2D carbon-based materials, i.e., graphene and its derivatives, have been identified as promising supports due to their large surface area, high affinity towards SMSs, high electric conductivity attractive for the electrocatalytic processes, and good stability. Furthermore, graphene enables efficient charge transport between the metal atom and the support, thus enhancing the catalytic activity10 or even conditioning the catalytic behavior of the atom for particular reactions.12 To effectively anchor SMSs, the presence of heteroatoms such as N, O, and S in the graphene support is crucial.10 So far, mainly graphene defects containing heteroatoms, particularly N-doped graphene, have been studied and utilized as SACs supports.13–15 Nevertheless, it is very challenging to gain control over the nature of the graphene defects. Recently, it has been proposed that materials containing graphene grafted with functionalities enabling selective coordination of metal atoms through chemical functionalization could be superior SAC substrates.1The development of SACs requires supports that effectively anchor single metal species (SMSs) responsible for the catalytic activity. Such effective anchoring should lead to SMSs in targeted redox and spin states, strongly interacting with the support to prevent unwanted migration and agglomeration of SMSs. Metal alloys, oxides, carbides, nitrides, sulfides, and carbon nanomaterials have been identified as suitable supports.i.e., graphane16 and fluorographene,17,18 a limited set of reactions involving pristine graphene such as cycloaddition19–21 and nucleophilic addition22 is known to offer graphene derivatives with more complex and defined functionalities. By contrast, graphene oxide (GO) prepared by harsh oxidation of graphite has received considerable attention over the past decade due to its cheap and affordable synthesis with mass production potential and the presence of a high number of oxygen-bearing groups, whose reactivity makes its further functionalization feasible.23 The nature of GO is, however, rather complex owing to the presence of various oxygen functions, with the resulting character of GO depending on the particular procedure of its synthesis.24 Moreover, a recent review on the utilization of GO as a support for the development of SACs has not covered controllable functionalization of GO with out-of-plane functionalities, focusing instead on its transformation into specific forms of N-doped graphene with anchored SMSs.23 In addition, GO is not an electrically conductive nanomaterial,25 which limits its application in electrocatalysis. GO can be  reduced to regain electrical conductivity,26 but such modifications are accompanied by the loss of significant amounts of functionalities.Due to its high chemical inertness, direct functionalization of graphene remains a challenging task. Except direct hydrogenation and fluorination of graphene, which leads to the formation of the only two stoichiometric graphene derivatives, 17,27 fluorographene (FG) was proposed as a handy starting material for controllable28 and scalable synthesis of highly functionalized graphene derivatives.29 The most straightforward options for FG synthesis are direct fluorination of graphene by gaseous elemental fluorine30 or XeF218,31,32 at elevated temperature, or by plasma treatment in the presence of elemental fluorine,33 CF4,34 fluoroform,35 or SF6.36 Additionally, photoinduced decomposition of fluoropolymer on graphene allows its patterned fluorination.37 Obtained FG can be applied in electronics due to its electro-insulating properties,38 as an electrode separator,39 as a matrix in MALDI mass spectrometry,40 in composites with perovskites for solar cells,41 and as coatings for its hydrophobicity.42 Nevertheless, FG used for the synthesis of graphene derivatives is mostly prepared by chemical exfoliation of graphite fluoride in a variety of organic solvents under sonication, which is a cheap, simple, and scalable method.29 Created well-processable FG dispersions can be directly reacted with various nucleophilic reagents under mild conditions in order to introduce a desirable group/molecule/functionality on a graphene platform with high control over the material stoichiometry and topology.29 Graphene derivatives prepared this way have numerous advantages over the materials derived from the extensively used graphene oxide. Their electric conductivity43 makes them applicable in electrocatalysis.44 They display good processability in the form of dispersions in a variety of solvents. They also offer a broad portfolio of homogeneously distributed functionalities covalently grafted onto the graphene lattice, and their further functionalization via the chemistry of the attached functionalities.45 Thanks to these properties, FG-derived materials can be efficiently utilized as supporting materials for SACs12,44–48 because introduced functional groups can immobilize SMSs and avoid undesirable processes such as the formation of larger metal clusters and the leaching of metal particles during reactions.Thanks to its reactivity,49 observed strong paramagnetism in highly-fluorinated graphene samples, ascribing it to radical point defects  that naturally form during the fluorination of graphene. Later, by combining the electron paramagnetic resonance (EPR) technique with density functional theory (DFT) calculations, Medveď et al.50 demonstrated that such radical sites play a crucial role in FG chemistry. Owing to their high electron affinity, they can accept an electron into the SOMO orbital and initiate the defluorination process even in the presence of mild reducing agents FG defluorination, such as DMF, NMP, acetone, and DMAc, covalent functionalization of (p)FG is often accompanied by either partial or complete defluorination of the material.27,43,52,53,58,63,64 On the other hand, in some cases, extensive defluorination of the material may be undesirable since it lowers the intrinsic self-lubricating ability of FG. This can be tackled by activating the dormant radicals in pFG, as demonstrated by acrylic acid and styrene, which bind to the pFG surface without losing fluorine ad-atoms.65 Due to their electron-withdrawing effect, residual F atoms make the prepared derivative act as a dienophile in Diels–Alder cycloaddition reactions, enabling to heterobifunctionalize graphene with functionalities that are otherwise impossible to graft at the same time.66 Nevertheless, tunable one-step double- or multi-functionalization of FG based on the nucleophilicity of the grafted molecules using nucleophiles is also feasible.67It is worth noting that not only radical point defects but also larger defluorinated areas like defluorinated chains, rings, or islands can be attacked by nucleophiles, as demonstrated in the case of covalent grafting of polysulfide chains to the surface of partially fluorinated graphene ((p)FG).et al.68 Successful attachment of nitrogen-containing functional groups to the surface of graphite fluoride and simultaneous defluorination of the material deploying benzylamine and tetramethylethylenediamine was explained as a so-called proton-coupled electron transfer. Interestingly, it was demonstrated that FG radical centers fostered the formation of iminium ion fragments from benzylamine and caused fragmentation of tetramethylethylenediamine. The resultant nitrogen moieties were able to attach to CC bonds in pFG or recombine in order to form various amines. A similar conclusion was achieved for the reaction of FG with NaNH2 in DMF solvent.60 The GC-MS analysis of the supernatant in combination with DFT calculations showed that FG radical centers allowed a variety of radical side reactions, leading to a number of possible by-products of the reaction.Recently, a slightly different reaction mechanism of FG functionalization was proposed by Siedle 69 A material based on FG modified with hydroxyl (–OH) groups that enabled a superexchange interaction between the spins of the parent FG was identified as the first organic material with room-temperature antiferromagnetic ordering with a transition into ferromagnetic regime at low temperatures.58 Spin-rich N-doped graphene (NG) prepared from FG using hydroxylamine exhibited spin-switch behavior under microwave radiation.70 Regarding energy storage applications, a sulfur-chain-functionalized graphene acted as a high-capacity cathode material for lithium–sulfur batteries.62 An N-doped derivative employing sodium azide exhibited unprecedentedly high capacitance with power density up to 200 Wh L−1 at a power of 2.6 kW L−1 in symmetric supercapacitors.61 Generally, as FG has been recognized for its susceptibility to reactions with organic amines,28,64 the resulting products of reactions of FG with 5-aminoisophtalic acid or arginine amino acid were tested as supercapacitor electrode materials with promising results.71,72 Controllable functionalization of FG with n-octylamine molecules allowed tailoring its nonlinear optical properties.73 As for the bio-applications of FG derivatives, the ability of thiol-functionalized FGs through the reaction with sodium hydrosulfide74 or via reaction with xanthogenate ion and subsequent hydrolysis of the prepared material75 to adsorb biomolecules, e.g., nucleic acids and enzymes, can be utilized in biosensing and environmental remediation. Modification of FG with chlorine atoms was achieved by immobilizing dichlorocarbene on the FG.76A plethora of FG derivatives see  with bro43 a nitrile groups-carrying material created by the substitution of FG's fluorine atoms with –CN groups using sodium cyanide, is among the most versatile FG-derived materials. Such functionality can anchor transition metal atoms, which can be utilized in SACs.12,47 It also creates a strong bond with silver nanoparticles, which hampers the defense mechanism of silver-resistant bacteria.77 The nitrile groups in GCN can be readily hydrolyzed into carboxyl (–COOH) groups, thus forming graphene acid (GA)43,78 that may be also utilized as a ligand for anchoring transition metals45 or as a recyclable substrate for water remediation or retrieval of precious metals from waste.79 It is worth noting that GA was successfully applied as an electrode material in supercapacitors80 and lithium-ion batteries.81 Using carbodiimides, GA can be conjugated with primary amines, allowing further functionalization, which makes GA a robust substrate for the immobilization of biomolecules used as nano(bio)catalysts82 and biosensing platforms.83 A network of carboxyl groups on graphene can be also achieved through the Bingel reaction of malonate ester with FG and its subsequent hydrolysis. Its conjugation with iron phthalocyanine resulted in a material with unprecedented capacitance due to the formed zwitterionic network of residual –COOH groups and Fe ions.84Cyanographene (GCN),46 Bakandritsos et al.12 successfully immobilized Cu(ii) ions by nitrile groups of GCN (ii) ions being reduced to Cu(i) (i) species, this mixed-valence Cu(ii)/Cu(i) catalyst was able to activate oxygen molecules and excelled in catalyzing an oxidative amine coupling (iii)/Fe(ii) cations immobilized on GA, detected by Mössbauer spectroscopy. The coordination of metal atoms or cations on the –CN and –COOH groups of GCN and GA is associated with a charge transfer between the substrate and SMS. The amount of the transferred charge correlates with the electron affinity of the bare metal cation and with the dissociation energy of the GCN/GA⋯Me bond.47 Interestingly, the analysis of spin populations of the metal atoms/cations anchored to GCN/GA demonstrated that their oxidation states were often the same despite their different initial charges. In the case of cation pairs Fe2+/Fe3+, Co2+/Co3+, and Cu+/Cu2+, this feature, in combination with high bond dissociation energy, could be used for designing new mixed-valence SACs. The ability of GCN to anchor metal cations was also discussed in the study of Kadam et al.44 on the successful design of Co-based SAC that has shown efficient and selective electrocatalytic activity toward hydrazine oxidation.First-principles calculations in combination with experimental data have confirmed that among graphene derivatives bearing –F, –OH, –CN, and –H functional groups, GCN equipped with nitriles was the only one that was able to bind Pt atom without compromising the structure of the material.s of GCN . High-reto Cu(i) . Indeed,coupling  and sele45 Blanco et al.48 succeeded in binding in situ formed ultrasmall (<1 nm) Pd nanoparticles to the –COOH groups of GA through a mild impregnation of GA with Pd(OAc)2 in acetonitrile. Such GA⋯Pd nanohybrids exhibited high catalytic activity in the Suzuki-Miyaura cross-coupling reaction under environmentally friendly conditions.48GA is another efficient supporting material for SACs and catalytically active metal nanoparticles.et al.85 reported a successful covalent functionalization of GA and GO with ferrocene (Fc) by conjugating both species with 1,3-diaminopropane (PDA)  . The resne (PDA) , the catne (PDA) . The bet88–92 For instance, Fe and Co atoms anchored to the N-doped carbon framework are active catalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and water splitting.4,6,15,89,90 However, to our best knowledge, there has been no report so far on Me⋯NG complexes synthesized using FG chemistry, even though FG is a promising precursor for the synthesis of NG with a tunable amount of nitrogen.60,61,70,93,94Not only covalent functionalization but also heteroatom doping of graphene offers promising active sites for immobilizing SMSs.e.g., enzymes, anchor catalytically active SMSs, and metal complexes  catalysis has not yet been implemented in any of the reported SACs so far due to the challenging control over the close environment of the metal atom. The chemistry of FG has the potential to overcome such limitations of SACs by grafting ligand functionalities onto graphene, providing a well-defined coordination sphere for the immobilized metal atom. Moreover, the introduction of chiral functionalities to graphene could also imprint stereospecificity to make recyclable chiral catalysts. We therefore propose that the immobilization of proven homogeneous metal catalysts onto graphene, deploying the principles of the chemistry of FG and GA summarized in this work, can be a route to straightforward development of new recyclable and possibly regioselective and stereospecific graphene-based SACs. The new generation of SACs derived from the FG chemistry would also benefit from the control of the single-atom valence state, sophisticated control of the SA coordination, and the active role of graphene support in the reaction mechanism.There are no conflicts to declare.