To study the role of ataxia telangiectasia mutated (ATM) in the platelet-derived growth factor (PDGF)-BB-induced proliferation of pulmonary arterial smooth muscle cells (PASMCs) through reactive oxygen species (ROS) formation.2O2). The activation level of ATM and the proliferation level of PASMCs were measured by immunofluorescence staining and Cell Counting Kit-8, respectively. Moreover, NADPH oxidase 2 (NOX2) and intracellular H2O2 were detected under the stimulation of different levels of PDGF-BB by Western blot and dihydroethidium staining.Primary cultures of PASMCs were treated with different concentrations of PDGF-BB or exogenous hydrogen peroxide (HP < 0.05). With the ATM inhibitor, 50 ng/ml of the PDGF-BB group showed further increased proliferative level compared to the 10 ng/ml (P < 0.05). Both the levels of NOX2 and H2O2 showed dose-dependent manners under PDGF-BB stimulation (P < 0.05). ATM could be activated by H2O2 upon a dose-dependent way, except for the 500 μM H2O2 group. Under 200 μM H2O2 stimulation, proliferation level decreased significantly (P < 0.05), while no significant difference was shown with the addition of ATM inhibitor (P > 0.05).Both the control group and 50 ng/ml of the PDGF-BB group showed significantly higher levels of phosphorylation ATM compared to other groups .Our study first established ROS-induced ATM activation in PDGF-BB-stimulated proliferation of PASMCs. Inhibition of ATM had promoted effects on the proliferation of PASMCs under the excessive levels of PDGF-BB and H Pulmonary arterial hypertension (PAH) is a chronic disease, characterized by the narrowing and obstruction of the small pulmonary arteries, which results in increased pulmonary vascular resistance, right heart failure, and probably causes death . AlthougAtaxia telangiectasia mutated (ATM) is a serine/threonine kinase. Together with DNA-dependent protein kinase catalytic subunits (DNA-PKcs) and ATM- and Rad3-related (ATR), these three are members of the phosphatidylinositol-3 kinase-like protein kinase (PIKK) family. When DNA damages occur, these proteins can activate the repair mechanism and suspend the duplication by activating the cell cycle checkpoint , 5. ATM Platelet-derived growth factor (PDGF) can act with PDGF receptor to promote the proliferation of human PASMCs. A clinical trial evaluating the PDGF receptor inhibitor has been carried out for treating PAH . In the 2O2) to stimulate the PASMCs under ATM inhibition to figure out the role of ATM in PASMCs proliferation.Thus, we conduct a PDGF-BB-induced PASMC proliferation system to study the role of ATM through the addition of ATM inhibitor, along with detecting the NADPH/ROS signaling activation under different concentrations of PDGF-BB stimulation. Furthermore, we use different levels of hydrogen peroxide (H2 atmosphere. Primary PASMCs were subcultured to the third generation and readied for the experiments. Anti-α-smooth muscle antibody (SMA) and antiosteopontin (OPN) antibodies were used to confirm the PASMCs . The third generation of PASMCs was treated with PDGF-BB for 24 h, following the starvation for 24 h in DMEM without FBS. The concentrations of PDGF-BB were 2, 10, and 50 ng/ml, while the same volume of PBS was added as the control group. A total of 3 μM of ATM inhibitor was administrated for 30 min prior to PDGF-BB treatment. After 24 h treatment, PASMCs were harvested for the next experiments .2O2 was prepared into 20, 100, 200, and 500 μM with serum-free DMEM. The third generation of PASMCs was cultured in different concentrations of H2O2 for 1 h with or without ATM inhibitor pretreatment, followed by the replacement of the medium to normal DMEM with 10% FBS for another 24 h. Then, PASMCs were harvested for the next experiments . Heriments .staining . The thi2. Absorbance was measured by a microplate reader under 450 nm.Cell Counting Kit-8 (CCK-8) was purchased from the Dojindo . According to the manufacturer's instruction, the third generation of PASMCs was cultured in a 96-well plate. After specific treatments, 10 μl of the CCK-8 solution was added to each well, followed by 2 h incubation at 37°C with a humidified 5% COImmunofluorescence Staining Kit was purchased from Beyotime . The third generation of PASMCs was cultured on the cover glass for a 48-well plate. All the procedures are strictly followed by the manufacturer's instructions. Briefly, cells are fixed and blocked by using the fixing buffer and blocking buffer, respectively. Antiphosphorylated ATM antibody  was used for incubation and detection at 4°C overnight. After removal of the primary antibody, a specific fluorescent enzyme-connected secondary antibody was used for 60 min in a dark chamber. The fluorescent microscope was used to detect the phosphorylated ATM, which submitted the red fluorescence.TM MP Imager . The densitometry values were measured using the FluorChem 8,000 software .Pulmonary artery smooth muscle cells were washed three times with PBS on the ice and lysed by NP40 lysis buffer  for 30 min. Cell lysates were collected and centrifuged at 12,000 g for 5 min at 4°C. The supernatant was kept and determined by BCA Protein Assay Kit . Proteins (50 μg/lane) were added and separated by electrophoresis on 10% polyacrylamide sodium dodecyl sulfate gels, followed by transfer to polyvinylidene fluoride (PVDF) membranes. The membranes were incubated with anti-NOX2 antibody at 4°C overnight and a secondary antibody for 60 min at room temperature. The blots were developed using the enhanced chemiluminescence (ECL) Western Blotting Detection System with a ChemiDocP < 0.05 was considered significantly different.All the data were presented as mean ± SEM. One-way ANOVA followed by the Bonferroni test was used to examine the statistically significant differences between multiple groups. P < 0.05). Further, proliferative level of PASMCs was measured by CCK-8 assay. Without the pretreatment of ATM inhibitor, 2, 10, and 50 ng/ml of groups showed a significant increase in proliferation compared with the control group. There is no significant difference identified between 10 and 50 ng/ml of groups. With the pretreatment of ATM inhibitor, proliferative levels of PASMCs under PDGF-BB treatment were not affected. Interestingly, a slight but significant difference was found between 10 and 50 ng/ml of groups . Our data suggested that PDGF-BB can increase the expression of NOX2 in a dose-dependent manner.Many studies revealed that NOX2 could produce Hulations . Additioons (2O2 . Therefo2O2 level. As shown in 2O2 level increased significantly (P < 0.05). More important, after the pretreatment of DPI, H2O2 level did not elevate after PDGF-BB stimulation (P < 0.05). These data demonstrated that PDGF-BB stimulation can promote the H2O2 accumulation and DPI, NOX2 inhibitor, can abolish this effect, which means that NOX2 took responsibility for the formation of H2O2.To further detect the level and its resource, we treated the primary PASMCs culture with different concentrations of PDGF-BB following 24 h starving. We also set the diphenyleneiodonium (DPI) group, which contained the 30 min pretreatment of DPI followed by 50 ng/ml of PDGF-BB treatment. DHE staining was performed to detect the H2O2 on PASMCs, we incubate the primary PASMCs with extra H2O2 . Proliferation study (CCK-8 assay) revealed interesting results (2O2 could significantly promote the proliferation of PASMCs compared to the control group (P < 0.05). With the stimulation of 200 μM H2O2, proliferation level decreased significantly (P < 0.05). However, with the addition of ATM inhibitor, proliferation level under 200 μM H2O2 did not show a further decrease compared with the control group (P > 0.05).To understand the role of Htra H2O2 . After 2 results . Lower lOur study first brought ATM mechanism into PAH by detecting ATM activation in PDGF-BB-stimulated proliferation of PASMCs. We revealed that the optimal level of PDGF-BB could activate the limited amount of ROS formation, which inhibited the phosphorylation of ATM and promoted the proliferation of PASMCs. However, a high concentration of PDGF-BB could not promote the proliferation of PASMCs, which might be caused by the accumulation of excessive ROS formation. Intriguingly, with the ATM inhibitor, a high level of PDGF-BB showed additional positive effects on the proliferation of PASMCs.Ataxia telangiectasia mutated is first identified in patients with ataxia telangiectasia, characterized by the extreme cellular sensitivity to radiation and a predisposition to cancer . Activatin-vitro PAH model to mimic the proliferation of PASMCs. Under different stimulation levels of PDGF-BB, we found the different activation levels of ATM. Interestingly, the ATM inhibitor could discharge the plateau effect of a high concentration of PDGF-BB and further promote the proliferation of PASMCs under the high level of PDGF-BB. In addition, under the low level of PDGF-BB stimulation, ATM kept inactivated status, while ATM was activated under serum-free conditions. Our study suggested that the functional status of ATM at least partially determines the proliferation of PASMCs with the stimulation of PDGF-BB.Recently, a review article revealed that the proliferation of PASMCs in pulmonary arterial hypertension showed many cancer-like characteristics. PASMCs showed similar patterns compared with the features of cancer cells, including cellular metabolic disorder, self-sufficiency in growth signals, insensitivity to antigrowth signals, limitless replicative potential, sustained angiogenesis, and evading apoptosis . In the 2O2. In our experiments, a lower level of H2O2 (< 200 μM) could promote the proliferation of PASMCs without activation of ATM. However, a higher level of H2O2 had negative effects on the proliferation of PASMCs, which could also activate the ATM. Surprisingly, with the inhibitor of ATM, 200 μM of H2O2 had no longer negative effects on the proliferation of PASMCs.Ataxia telangiectasia mutated is reported to not only respond to the DNA double-strand breaks, but also be activated under oxidative stress . It is r2O2 level under different concentrations of PDGF-BB stimulation. Both the activation level of NOX2 and H2O2 level showed a dose-dependent way of responding to the stimulation of PDGF-BB. Taken together, we suggested that PDGF-BB could induce ROS through NOX2 activation. With the accumulation of excessive ROS, ATM can be activated to call for the cell cycle arrest to stop the proliferation of PASMCs. More importantly, with the ATM inhibitor, a higher proliferation level of PASMCs was shown compared to the same condition without the ATM inhibitor.Many studies demonstrated that dysfunction of mitochondria, activation of NOX family, and uncoupled NOS contribute to the ROS formation in PAH . It is sTo summarize our study, we first established the role of ATM in the PDGF-BB-stimulated proliferation of PASMCs. The generation of ROS from NOX2 was involved in this new pathological mechanism in PAH. Our study might provide a new pharmacological target for the treatment of PAH, which was to restore the ATM function to prevent the pathological proliferation of PASMCs. According to the study in oncology, we hypothesized that the genetic dysfunction of ATM might take responsibility for PAH, which needs further clinical data about patients with PAH to confirm.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The animal study was reviewed and approved by the Ethics Review Boards at the Sichuan University.CQ and YZ accomplished most cell studies and biological studies. CQ wrote this manuscript. LX helped cell studies and biological studies. HL designed the study and supervised the whole experiments. All authors contributed to the article and approved the submitted version.This study was supported by the National Scientific Foundation of China (81700311).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.


Development of the Italian clinical practice guidelines on bariatric and metabolic surgery, as well as design and methodological aspects. Background: Obesity and its complications are a growing problem in many countries. Italian Society of Bariatric and Metabolic Surgery for Obesity  developed the first Italian guidelines for the treatment of obesity. Methods: The creation of SICOB Guidelines is based on an extended work made by a panel of 24 members and a coordinator. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methodology has been used to decide the aims, reference population, and target health professionals. Clinical questions have been created using the PICO  conceptual framework. The definition of questions used the two-step web-based Delphi method, made by repeated rounds of questionnaires and a consensus opinion from the panel. Results: The panel proposed 37 questions. A consensus was immediately reached for 33 (89.2%), with 31 approved, two rejected and three which did not reach an immediate consensus. The further discussion allowed a consensus with one approved and two rejected. Conclusions: The areas covered by the clinical questions included indications of metabolic/bariatric surgery, types of surgery, and surgical management. The choice of a surgical or a non-surgical approach has been debated for the determination of the therapeutic strategy and the correct indications. Obesity and its complications are a growing public health concern in many countries, due an increasing prevalence, a relevant impact on the health of affected individuals and a growing related economic burden . TreatmeThe development of rigorous guidelines is a relevant tool for the improvement of the quality of care, increasing the appropriateness of therapeutic choices. The Italian Society of Bariatric and Metabolic Surgery for Obesity  recognized this need and decided to design and develop the first Italian guidelines, aimed at assisting healthcare professionals in the consideration of the surgical option for the treatment of obesity and related conditions. In the Italian national legal environment , the incPanel members, identified by SICOB in collaboration with other scientific societies All members of the panel and evidence review team compiled a declaration of potential conflicts of interest, which were collectively discussed to determine their relevance. In all cases, the reported conflicts were considered minimal or irrelevant; therefore, all components of the panel and of the evidence review team participated in the elaboration of all recommendations.The GRADE method  was deveThe following step is that of defining a series of clinical questions, using the PICO  conceptual framework . Each reFor each question, the panel defines a number of clinical outcomes, which are potentially relevant for the choice of different clinical options. Each outcome is then rated (from 1 to 9) for its importance; those receiving a rating of 7 or higher are classified as “critical” and represent the basis for the development of the recommendation.For each critical outcome, the evidence review team will perform a systematic review of relevant studies, predefining search strategies and inclusion criteria, and performing meta-analyses whenever possible Further assessments include economic evaluations , organizational impact, equity, acceptability, and feasibility. The final recommendation includes all those elements.The definition of questions was performed using a two-step web-based Delphi method, a structured technique aimed at obtaining, by repeated rounds of questionnaires, a consensus opinion from a panel of experts in areas wherein evidence is scarce or conflicting, and opinion is important .Between June and October 2022, panelists were invited to propose questions with the PICO framework and to express their level of agreement or disagreement on each proposed question using a 5-point Likert scale, scored from 1 to 5 . Results were expressed as a percentage of respondents who scored each item as 1 or 2 (disagreement) or as 3, 4, or 5 (agreement). A positive consensus was reached in case of more than 66% agreement, a negative consensus in case of more than 66% disagreement, consensus was not reached when the sum for disagreement or agreement was below 66% . For the2 requiring bariatric or metabolic surgery. Healthcare systems, infrastructures, human and financial resources across Italian regions will be considered in developing these guidelines. Therefore, they are primarily intended to be applicable in Italy. The present guidelines will be used by healthcare professionals, including surgeons, obesity specialists, general practitioners, nutrition experts, psychologists, endocrinologists/diabetologists, and pediatricians.These guidelines will apply to adolescents (age > 13 years), adults, patients with Body Mass Index (BMI) > 30 kg/mThe panel therefore identified 32 clinical questions, organized into six domains:A.Indication for surgery (11 questions);B.Perioperative work-up/management (9 questions);C.Bariatric procedures (5 questions);D.Endoscopic procedures (1 question);E.Revisional surgery (2 questions);F.Postoperative care (4 questions).The approved questions and their related approved critical outcomes are reported in The evidence review team identified the characteristics of relevant studies for each critical outcome, defining search strategy and study inclusion criteria, which are reported in The areas covered by the clinical questions identified by panelists include indications of metabolic surgery, types of surgery, and pre-, peri- and post-surgical management of obese patients. The focus on indications is not surprising: the choice of a surgical or a non-surgical approach for the treatment of obesity and related metabolic conditions is often debated, posing relevant issues for the determination of appropriateness of the therapeutic strategy. In addition, considering the current legislation on professional liability , a correThe focus on procedures to be applied before, during and after the surgical procedure, is less obvious. Interestingly, the identification of those questions was performed by a panel mainly composed of surgeons, showing a clinical vision much broader than the surgical act per se.Some questions were devoted to the application of surgical procedure for the treatment of obesity-related conditions, such as T2D. The possibility of using surgical techniques to treat T2D and other diseases associated with excess weight, even in patients with mild obesity, or not even properly obese, has been pursued by some authors ,4; promiObese patients seeking treatment have expectations of weight loss. Conversely, health professionals have a greater attention to obesity-associated metabolic abnormalities, such as hyperglycemia, dyslipidemia, etc. The panelist planning the development of these guidelines reached one step further, recognizing the central role of longer-term hard outcomes, such as mortality, incident cardiovascular disease, and malignancies. The availability of sufficient evidence for a reliable assessment of the effects of surgery on those outcomes will be verified in the process of developing these guidelines. Appropriately sized, long-term studies on hard outcomes can be considered a priority for research.The choice of a specific therapeutic strategy should be based on the assessment of the risk-benefit ratio, together with cost-utility analysis. This means that adverse events need to be systematically and carefully studied. In fact, safety outcomes have been included for most clinical questions, concurring to the development of recommendations.Transparency in the development process is one of the main determinants of quality of guidelines ,17,18,19The creation of SICOB Guidelines is based on an extended work. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methodology has been used to decide aims, reference population, and target health professionals. Clinical questions have been created using PICO  conceptual framework. The GRADE manual recommends the explicit publication of clinical questions, relevant outcomes, and summaries of evidence for each outcome. The search strategy and inclusion criteria for the systematic review and meta-analysis for each outcome has been reported in the present study, allowing for the reproducibility of the whole process.


Frontotemporal dementia (FTD) covers a spectrum of neurodegenerative disorders with various clinical and neuropathological subtypes. The two major pathological proteins accumulating in the brains of FTD patients, depending on their genetic background, are TDP-43 and tau. We aimed to evaluate whether total TDP-43 levels measured from the serum associate with the genotype or clinical phenotype of the FTD patients and whether serum TDP-43 provides prognostic or diagnostic value in the FTD spectrum disorders.The study cohort included 254 participants with a clinical diagnosis of FTD  and 105 cognitively healthy controls. Serum total TDP-43 levels measured with a single-molecule array (Simoa) were compared within the FTD group according to the genotype, clinical phenotype, and predicted neuropathological subtype of the patients. We also evaluated the associations between the TDP-43 levels and disease severity or survival in FTD.B = 0.181, 95%CI = 0.014–0.348, p = 0.034). The lowest TDP-43 levels were observed in the subgroup of FTD patients harboring predicted TDP-43 brain pathology . The low levels in the FTD-TDP group were especially driven by C9orf72 repeat expansion carriers (169.2 pg/mL) and FTD patients with concomitant motoneuron disease , whereas GRN mutation carriers did not show decreased TDP-43 levels (328.6 pg/mL). Serum TDP-43 levels showed no correlation with disease severity nor progression in FTD.Total TDP-43 levels in the serum were significantly lower in the FTD group as compared to the healthy control group (275.3 pg/mL vs. 361.8 pg/mL, C9orf72 repeat expansion or FTD-MND phenotype, both subtypes strongly associated with TDP-43 type B brain pathology. Serum-based measurement of TDP-43 could represent a useful tool in indicating C9orf72 repeat expansion and FTD-MND-related TDP-43 neuropathology for future diagnostics and intervention studies.Our results indicate that the total levels of TDP-43 in the serum are decreased especially in FTD patients with the  C9orf72 (C9-HRE) and mutations in the GRN or MAPT genes  . The Simt-test (or Mann-Whitney U for non-parametric variables) to compare age and neuropsychological data distribution between the groups. Correlations between serum TDP-43 levels and other continuous variables were analyzed with Spearman’s rank correlation test or Pearson’s correlation test (depending on the variable distribution). Due to the non-normally distributed TDP-43 data , natural logarithmic transformation was performed (ln-sTDP-43). Differences in serum TDP-43 levels between the diagnostic groups and between the genetic and predicted neuropathological subgroups were evaluated with a multivariate linear regression model adjusted for age and sex. When evaluating diagnostic accuracy, receiver operating characteristics (ROC) curve analysis was used to calculate the area under the curve (AUC) values . A p-value ≤ 0.05 was considered as statistically significant.Statistical analyses were performed using IBM SPSS Statistic version 25 and GraphPad Prism Software version 5 and version 9. The chi-square analysis was used to compare gender distribution and independent sample Demographics of the study cohort are shown in Table N = 359; r = 0.095, p = 0.075) or separately in the FTD group  but showed a significant correlation in the HC group only . When the effect of gender was considered, males had a trend for slightly higher levels of serum TDP-43, but the age-adjusted gender differences were non-significant in the total study cohort , in the HC group , and in the FTD group .Serum TDP-43 levels showed no significant correlation with age at baseline in the total study cohort  vs. the HC group (N = 105) indicated that the levels were significantly lower in the FTD patients compared to HC  when adjusted for age and gender  compared to the HC group (N = 105)  after similar adjustments (age and gender), whereas the TDP-43 levels did not significantly differ between the FTD-tau group (N = 27) and the HC group (N = 105)   showed lower serum TDP-43 levels compared to the FTD-tau group (N = 27)  when adjusted for age and gender  , while the highest levels were found in PSP patients  . The levels in bvFTD patients , nfvPPA patients , and svPPA patients  were in between these extremes. When compared to the HC group  adjusted for age and sex, statistically significant differences were observed between FTD-MND and HC  and between bvFTD and HC   and HC (N = 105) , while no significant differences were found between the GRN mutation carriers (N = 31) (328.6 pg/mL) vs. HC . Furthermore, as expected, no differences between MAPT mutation carriers (N = 3) (361.6 pg/mL) and HC (361.8 pg/mL)  or non-genetic FTD (N = 170) (291.9 pg/mL) vs. HC  (adjusted for age and sex) were detected. When the genetic FTD patient groups  were independently compared to the non-genetic FTD group, only the difference between C9-HRE and non-genetic FTD was statistically significant  , a statistically significant difference was observed between C9-HRE carriers and HC (area under the curve (AUC) = 0.765, with 72% sensitivity and 75% specificity, cutoff 174 pg/mL) and between FTD-MND and HC . In the ROC analysis between the FTD-TDP and FTD-tau groups, the AUC was 0.689 with 63% sensitivity and 68% specificity (cutoff 267 pg/mL). C9-HRE and the FTD-MND phenotype are associated with TDP type B pathology, whereas GRN mutations are associated with TDP type A pathology [GRN mutation carriers were excluded from the whole FTD-TDP group to generate a more specific “FTD-TDP type B” subgroup and compared to the FTD-tau group, the AUC was 0.860 with 85% sensitivity and 77% specificity (cutoff 173 pg/mL).In receiver operating curve (ROC) analyses, the best diagnostic accuracies of serum TDP-43 levels were observed between athology . When GRrs = 0.017, p = 0.807). The survival time was available for Finnish FTD patients (N = 107). Of these, 47/107 died during the follow-up, and the mean disease duration was 4 years. The serum TDP-43 levels did not associate with survival time after the diagnosis in the total FTD group , in the FTD-TDP subgroup , nor in the C9orf72 repeat expansion carrier group .Finally, we investigated if serum TDP-43 levels showed a correlation with the severity or progression of the disease in FTD patients. The results indicated that the serum TDP-43 levels did not correlate with disease severity when assessed by using the FTD-CDR sum of boxes score , e.g., related to differential release or degradation of different TDP-43 forms. Future improved assays, specifically targeting specific TDP-43 forms will help in clarifying the reason underpinning the observed decrease in the serum TDP-43 levels.Our findings showing decreased, rather than increased, total TDP-43 levels in the serum of FTD patients with suspected TDP-43 pathology are in line with a previous study that assessed both total TDP-43 and pTDP-43 in a small cohort of genetic FTD patients, including ten carriers . The stu amounts . In our C9-HRE genotype and FTD-MND phenotype indicating that mainly C9-HRE and FTD-MND-related TDP-43 pathophysiology (TDP type B pathology in C9-HRE carriers and FTD-MND patients vs. TDP type A pathology in GRN mutation carriers) is reflected to the total TDP-43 serum levels measured with Simoa assay. Our findings are in contrast to a previous study, which reported decreased plasma TDP-43 levels also in the GRN mutation carriers [GRN mutation-carrying patients in the present study as compared to the previous one [GRN patients) in the previous study or the fact that different assay methods were used to detect TDP-43 (ELISA in the previous study vs. ultrasensitive Simoa in the present study).Notably, the lowered levels of total TDP-43 in the FTD-TDP group were strongly driven by the carriers . The undious one  could beC9-HRE as well as GRN mutation carriers have a more pronounced TDP-43 accumulation in their brain and concurrently increased release of pTDP-43 from the degenerating neurons, indicated by the higher pTDP-43 levels in the biofluid samples. Given the previous study reporting an inverse correlation of the levels of pTDP-43 and total TDP-43 [C9-HRE/FTD-ALS related disease. Thus, lower levels of TDP-43 in the biofluids, such as serum, could resemble the behavior of β-amyloid as a biomarker in Alzheimer’s disease (AD) patients. It has been reported that decreased β-amyloid levels in the CSF or blood are a hallmark of increased β-amyloid accumulation and aggregation in AD brain [Lower levels of especially total TDP-43 have also been observed in the lumbar CSF of FTD-TDP patients , a findil TDP-43 , it is pAD brain , 35. SimAD brain , the totAD brain . On the AD brain , and thiC9orf72, GRN, or MAPT as well as patients displaying diverse clinical phenotypes. Moreover, in comparison with some other previous studies, which utilized standard ELISA-based detection of TDP-43, we used here the ultrasensitive Simoa method, which allows the detection of targets with a low abundance. The levels of TDP-43 in none of our cases remained below the detection limit, which has been a substantial issue in the previous studies using other analysis methods. The limitations include the fact that although the genetic subgroups were the largest reported thus far, they still are fairly small when considering optimal statistical power in the subgroup analyses . Another limitation is that we did not have the option to correlate the serum levels of TDP-43 to the levels or accumulation of TDP-43 (or pTDP-43) in the brain of the same patients. These analyses could be done in the future in other cohorts, which contain both biofluid and brain samples from the same individuals. They would be helpful for testing the hypothesis of whether lowered serum levels of TDP-43 reflect a more pronounced brain pathology, similarly to β-amyloid in the AD patients. Furthermore, the measurement of serum TDP-43 in a longitudinal setting might also provide further insight into this idea. It should also be noted that the Simoa TDP-43 assay used here is not specific for the pathological truncated and phosphorylated forms of TDP-43 as it detects also the full-length TDP-43 protein. Although significant differences were found between the groups, the overlap in the TDP-43 levels between several groups was substantial , thus limiting the discriminative power of total TDP-43 levels detected using the present Simoa assay. Moreover, TDP-43 is not specifically expressed only in the central nervous system but is expressed also diversely in peripheral tissues. This might also partially explain the overlap between the groups and the differences between different studies. In the future, the diagnostic potential of TDP-43 measurements could be improved by combining measurements of TDP-43 levels with those of other biomarkers, or by developing specific and sensitive assays against different post-translationally modified TDP-43 protein forms, especially the truncated and phosphorylated forms, which associate with pathological changes in the brain.The main strength of the present study is the large and well-characterized multicenter cohort, which includes genetic patients carrying any of the three major FTD-associated mutations in either C9-HRE and FTD-MND related TDP-43 pathology as compared to healthy controls or patients with suspected tau pathology. This result may aid in the much-needed discovery of reliable biomarkers, which would enable distinguishing the different neuropathological subtypes of the FTD spectrum already in the early disease phases in living patients. The discovery of non-invasive, easily accessible, and reliable biomarkers is an essential step for accurate and timely diagnosis and, ultimately, for the development of specific therapeutic strategies targeting the underlying pathological mechanisms in different subtypes of FTD.Our results demonstrate significantly lower serum total TDP-43 levels especially in the FTD patients with


On the demand of low-cost, lightweight, miniaturized, and integrated optical systems, precision lenslet arrays are widely used. Diamond turning is often used to fabricate lenslet arrays directly or molds that are used to mold lenslet arrays. In this paper, mainly by real-time monitoring position following error for slow tool servo, different fabrication parameters are quantitatively studied and optimized for actual fabrication, then by actual fabrication validation, uniform and high-fidelity surface topography across the actual whole lenslet array is achieved. The evaluated fabrication parameters include sampling strategy, inverse time feed, arc-length, etc. The study provides a quick, effective, and detailed reference for both convex and concave lenslet array cutting parameter selection. At the end, a smooth zonal machining strategy toolpath is demonstrated for fabricating concave lenslet arrays. Micro-lsearched . Alternasearched ,7. The dsearched . AnotherThere are varieties of factors that can affect the final fabricated surface finish, such as cutting parameters, tool paths, temperature, cutting fluids, external vibration, and the vibration between the diamond tool and workpiece ,13,14,15To further improve fabricated lenslet array surface topography, this paper, by monitoring position following error, quantitatively studies the impact of sampling strategy, inverse time feed, sampling arc length, fabrication efficiency, and convex and concave lenslet configuration difference. Furthermore, using position following error mitigation methodology as guidance, actual lenslet arrays are fabricated and the improvement in surface topography at the outer region and uniformity across the whole array are verified. At the end, a smooth zonal machining toolpath methodology is introduced, and excellent surface form accuracy for both center and outer region concave lenslets is demonstrated.Here, the study’s geometrical feature is a lenslet array. It comes with two configurations: convex and concave, as shown in To generate the tool path for a designed lenslet array surface, considering the diamond turning conventional spiral tool path, we first generated a spiral curve on a flat surface, and then projected the spiral curve to the designed lenslet array surface. After that, taking the tool radius and rake angle into account, the tool path was generated by implementing cylindrical-coordinate based tool compensation . In thisTo study how well the lenslet can be fabricated, Nanotech 350FG was utilized to fabricate a 14 mm outer-diameter PMMA convex lenslet array, in which each lenslet had a radius of 6.3 mm and a clear aperture 0.35 mm × 0.35 mm. In the first study, a 0.25° constant-angle sampling strategy was applied, corresponding to 1440 points in one rotation cycle. In addition, an inverse time feed of 0.001 s was used. After the fabrication, the sample was measured with a Zygo NewView 8300 white light interferometer, with the measured result shown in To minimize the deterioration and determine the underlying root cause, we introduced PMAC (Programmable Multi-Axis Controller) to capture the real-time motion data, including command position, actual position, their associated acquisition time, etc., so that we could go further into analyzing and understanding the fabrication process. The position following error later discussed in this paper is the difference between the command and actual position.By using PMAC, real-time process data were acquired. Now, knowing the lenslet surface quality deteriorates from center to edge and that the center maintains fidelity to the actual design very well, the whole lenslet array uniformity can be identified if an indicator of outer-region lenslet surface topography is identified. As mentioned previously, the position following error represents local discrepancy very well, which makes it a potential candidate for the indicator. To check it, using the same methodology used in Although it is a small angle for the 0.25° angle cutting condition, it still exceeds the 30 µm arc length for two adjacent points at the edge of the 14 mm outer-diameter lenslet array, which is a large stroke length considering it is a freeform surface with complex local features. This may lead to the surface feature not being sufficiently sampled. In addition, between two adjacent points, the machine performs linear interpolation and a potential desired curve motion is simplified as a straight line, which is called the linearization error, the impact of which has been studied . HoweverWith the overshoot phenomenon in To characterize the inverse time feed more carefully, a further study was conducted. All other parameters remained the same, but only one variable—inverse time feed—was tested, and 0.001 s, 0.002 s, 0.003 s, 0.004 s 0.005 s, and 0.006 s were chosen. For each inverse time feed, the position following error for at least one complete spindle rotation cycle was gathered, and then all peak values demonstrated in Alternative to directly controlling the STS inverse time feed for each step, varying two adjacent arc lengths is an indirect method to alter the command frequency. Therefore, from a position following error perspective, a systematical study for arc-length impact was conducted.Obviously, any arbitrary arc length can be picked, but a small arc length means more stroke step numbers for the same total trajectory. Then, in a practical fabrication environment, a tradeoff needs to be carried out with the goal of achieving a reasonable surface quality for task-specific applications within a reasonable amount of time. To quantitatively understand the role that constant-arc plays in the position following error mitigation process, a study was carried out. In the study, all other parameters remained constant, with only one variable—different arc length—being selected, with representative ones across the spectrum: 0.625 µm, 1.25 µm, 2.5 µm, 5 µm, 10 µm, and 15 µm. For each arc length, similar to Naturally, the combined effect of the STS response time and constant-arc was studied. With the results of the position following error and machining efficiency demonstrated in So far, In addition to the sample shown in To associate the previous tested position following error with actual fabricated lenslet topography, the outer regions of six cases of the above-fabricated lenslet arrays were characterized, and specifically, the fifth-position lenslet, as shown in For the constant-arc, demonstrated in The surface error associated with the convex or concave configuration can be fully explained from a comparison of surface shape in To further investigate the uniformity of lenslet array surface topography from the center region to the outer region, for the six cases of the above fabricated lenslet arrays, the Sq (root-mean-square surface roughness) and Sa  of five lenslets was plotted in All of the study in In this paper, using real-time monitoring slow-tool servo position following error, different fabrication parameters were quantitatively studied and optimized, uniform and high-fidelity surface topography across the actual whole lenslet array was achieved and validated by actual fabricated results. Specifically, through PMAC real-time monitoring position following error at the lenslet array outer region, this paper quantitatively studied the impact of different sampling strategies, inverse time feed and arc-length, along with their associated total machining time consumption for STS. It provides a quick, effective, and detailed reference for both convex and concave lenslet array cutting parameter selection. In the end, a zonal machining strategy was demonstrated, and uniform and high-fidelity surface topography across the whole lenslet array was also achieved.


The binding energy, bond length, projected density of states and differential charge density of graphene–metal interfaces are investigated using a first-principles method in which a single layer graphene is adsorbed on the low-index metal surfaces such as the (111), (110) and (100) surfaces. The bond length results show the graphene sheet has a different degree of buckling after graphene is adsorbed on the (110) and (100) surfaces of metals. The projected density of states and the differential charge density results confirm the adsorption of graphene on the Ni(111), Co(111), Ni(110), Co(110) and Cu(110) surfaces is chemisorption due to the strong orbital coupling effect and the obvious charge accumulation between the carbon and metal atoms, while the adsorption of graphene on the Cu(111) surface is physical adsorption owing to the absence of the orbital coupling effect and the charge accumulation between the carbon and Cu atoms. Interestingly, the adsorption of graphene on the (100) surface of Ni, Co and Cu is all physical and chemical mixed adsorption because there are the strong orbital coupling effect and the apparent charge accumulation between the carbon and metal atoms in some parts of these surfaces while there are almost no orbital coupling effects and charge accumulation between the carbon and metal atoms in other parts. Unlike (111) and (110) surfaces, we find graphene is both physically and chemically adsorbed on the (100) surface of metals. These unique properties of graphene make it a hot research topic in the field of materials science, and endow graphene-based composites with better properties.9 Graphene–metal composites are an important part of the research on graphene-based composites, mainly including graphene-loaded metal nanoparticle composites and graphene–reinforced metal matrix composites. Graphene-loaded metal nanoparticle composites utilize graphene as the carrier to load metal nanoparticles in order to enhance the activity and dispersion of nanoparticles, which are applied in a broad range of fields such as catalysis,10–12 sensors,13,14 spectroscopy15,16 and so on. Graphene–reinforced metal matrix composites incorporate graphene sheets into the metal matrix, which can greatly enhance mechanical properties of metal materials without affecting or even improving the thermal and electrical properties of materials.17–19 Obviously, the interactions between graphene and metals will play a crucial role in the properties of graphene-based composites. Therefore, it is essential to study the interactions between graphene and different metal surfaces. There have been numerous experimental and theoretical studies on graphene contacted to metals such as Ni, Co, Ru, Rh, Pd, Ir, Pt and Cu.20–37 Experimental studies about the growth of graphene on metal close-packed surface such as Ni(111), Cu(111) and Ru(0001) rank first.38–41 Secondly, experimental studies about the growth of graphene on other low-index metal surfaces such as Ni(100), Rh(100) and Pt(110) have also been reported.42–44 However, theoretical studies on the interfaces between graphene and metals mainly focus on the metal close-packed surface such as Ni(111), Co(111), Cu(111) and so on.28–37 In 2018, Mafra et al. not only investigated different growth mechanisms of graphene on Ni(100), (110) and (111) surface by optical microscopy, Raman spectroscopy and optical transmission but also provided an atomistic model of the processes involved to support the experimental results by density functional theory calculations.43 Theoretical studies on the adsorption of graphene on the (110) and (100) surfaces of other metals except Ni are rarely reported.Graphene, a two-dimensional single atomic layer structure which is composed of spThe (111), (110) and (100) surfaces are the most basic and important low-index metal surfaces. In particular, the close-packed structure of the (111) surface of Ni, Co and Cu has been commonly used to make graphene–metal contacts owing to their structural resemblance. The difference is the adsorption of graphene on the (111) surface of Ni and Co is chemisorption while the adsorption of graphene on the Cu(111) surface is physical adsorption. However, the lack of hexagonal symmetry of (110) and (100) surfaces results in less theoretical studies on graphene–metal contacts. Therefore, in this work, in order to explore the adsorption mechanism of graphene on metal surfaces, taking Ni, Co and Cu as examples, the interfaces between graphene and low-index metal surfaces such as (111), (110) and (100) surfaces are investigated by using first-principles calculations at the level of density functional theory (DFT). The results obtained by the present study are not only expected to explain the adsorption mechanism of graphene on the metal surfaces, but also to provide help for the research of graphene-based composites and carbon nanomaterials.ab initio simulation package (VASP).44,45 The local density approximation (LDA)46 was used to describe the exchange correlation effect because of the better performance of LDA compared with the generalized gradient approximation (GGA) in predicting binding behaviour for interfaces between carbon nanostructures and metals.26,47 The projector-augmented wave (PAW) was used to describe the electron–ion interactions.48,49 Metal surface is constructed in a supercell as a finite number of layers of metal plus a region of vacuum repeated periodically in the direction perpendicular to the layers. The supercell used to model the graphene–metal interface is constructed from a slab consisting of six layers of metal atoms, with a graphene layer adsorbed from the top side of the slab and a vacuum region of 15 Å. Considering that the metal substrate is usually much thicker than the upper layer film and it is usually the film that trends to match the lattice constant (LC) of the metal substrate in experiment,50,51 the lattice constant of metal unit cells is fixed to construct the interface supercell. Therefore, taking the metal Ni as an example, the 4 × 4 graphene unit cell is adjusted to the 4 × 4 unit cell of Ni(111) surface as shown in  graphene unit cell is adjusted to the  unit cell of Ni(110) surface as shown in  graphene unit cell is adjusted to the 2 × 7 unit cell of Ni(100) surface as shown in  graphene unit cell is adjusted to the 2 × 5 unit cell of Cu(100) surface in order to build a better matching model as shown in 52 The electronic self-convergence criterion is set to 1.0 × 10−5 eV and the forces on all the atoms are converged to within 0.01 eV Å−1 with respect to ionic relaxation.Density function theory (DFT) calculations based on plane-wave basis sets of 500 eV cut-off energy were performed with the Vienna deq), the binding energy (Eb) for graphene adsorbed on the (111), (110) and (100) surfaces of metals and the maximum buckling on the graphene layer studied in this paper are listed in 28,43 but the overall trend is basically the same. We believe the difference in results may be due to the following reasons. Firstly, the supercells we constructed are larger than those in the literature28,53 when graphene is adsorbed on the (111) surface of metals. Besides, the adsorption configuration of graphene on the (111) surface of metals is different from that in the literature,28 but this configuration has been confirmed by experiments.34 The binding energy in the paper was calculated by underlying formulaEgraphene, Emetal surface and Egraphene–metal interface represent the total energy of the bare slab, the isolated graphene, and the adsorption system, respectively. According to the definition, a positive Eb indicates the adsorption system should be stable. Buckling is defined as the coordinate difference of carbon atoms along the z direction.The average equilibrium interfacial distance (deq) and the binding energy (Eb) show the adsorption types of graphene on the (111) surface of metals can be divided into chemisorption and physical adsorption according to the literature.27 To be more specific, when deq is less than 2.3 Å and Eb is greater than 0.1 eV per C, the adsorption of graphene on the (111) surface of metals is chemisorption, while deq is greater than 3 Å and Eb is less than 0.04 eV per C, the adsorption of graphene on the (111) surface of metals is physical adsorption. Combining the above criterion of adsorption type and our calculation results, it can be found the adsorption of graphene on the (111) surface of Ni and Co is chemisorption, while the adsorption of graphene on Cu(111) surface is physical adsorption. However, for graphene adsorbed on the (110) surface of metals, the average equilibrium interfacial distances are less than 2.3 Å, the binding energies of the graphene–Ni(110) interface and the graphene–Co(110) interface are greater than 0.1 eV per C while the binding energy of the graphene–Cu(110) interface is less than 0.04 eV per C. Unlike graphene adsorbed on the (111) surface of metals, the graphene sheet shows a certain degree of buckling. Therefore, the adsorption type of graphene on the (110) surface of metals needs to be further investigated. In terms of graphene adsorbed on the (100) surface of Ni and Co, the average equilibrium interfacial distances are less than 2.3 Å and the binding energies are 0.175 and 0.162 eV per C, respectively. Notably, when graphene is adsorbed on Cu(100) surface, the average equilibrium interfacial distance is more than 2.3 Å but less than 3 Å, and the binding energy is still less than 0.04 eV per C. However, the adsorption type of graphene on the (100) surface of metals also needs to be further investigated because the graphene sheet has a greater degree of buckling after graphene is adsorbed on the (100) surface. In conclusion, it is unreasonable to analyse the adsorption types of graphene on the (110) and (100) surfaces of metals by combining the binding energy and the average equilibrium interfacial distance due to no consideration for the buckling on the graphene sheet. In order to determine the adsorption types of graphene on different surfaces of Ni, Co and Cu more accurately, the bond lengths (r) between carbon and metal atoms at the interface can be used as a new criterion since the adsorption types of graphene on the (111) surface of Ni, Co and Cu can be determined. And the bond length (r) analysis will be discussed in the following paragraphs.In our calculations, all graphene-metal interface models can be confirmed to be stable according to the definition of the binding energy. All the initial configurations are shown in r) of carbon and metal atoms have changed to achieve the lowest energy state after graphene is adsorbed on metal surfaces. Local configurations are selected as the research object in order to better observe and compare the relative positions and the bond lengths (r) between carbon and metal atoms. It should be noted that local configurations are taken from the red line frame areas in r) between carbon and metal atoms induced by the adsorption of graphene on the (111) surface of Ni, Co and Cu are shown in r) between carbon and metal atoms at the interface are about 2.2 Å, indicating carbon atoms can form covalent bonds with metal atoms, that's to say, the adsorption of graphene on Ni, Co and Cu surfaces is chemisorption, while the bond lengths (r) between carbon and metal atoms are larger than 3 Å, indicating carbon atoms don't form covalent bonds with metal atoms, that's to say, the adsorption of graphene on Ni, Co and Cu surfaces is physical adsorption.The initial configurations were constructed by matching graphene to metal surfaces as shown in r) of carbon and metal atoms induced by the adsorption of graphene on the (110) surface of metals. The maximum and minimum bond lengths (r) between carbon and Ni atoms are 2.357 Å and 2.009 Å, respectively. And the maximum and minimum bond lengths (r) between carbon and Co atoms are 2.398 Å and 2.039 Å, respectively. According to the new criterion mentioned above, it is known that the adsorption of graphene on the (110) surface of Ni and Co is chemisorption. However, for the graphene–Cu(110) interface, the minimum bond length (r) between carbon and Cu atoms is 2.218 Å, which is very close to 2.2 Å, while the maximum bond length (r) between carbon and Cu atoms is 2.770 Å, which is slightly larger than 2.2 Å, but less than 3 Å. In general, the adsorption of graphene on Cu(110) surface is also chemisorption, but the interaction between carbon and Cu atoms is slightly weaker than that between carbon and Ni (or Co) atoms.Unlike graphene adsorbed on the (111) surface of Ni, Co and Cu, the graphene sheet shows a certain of buckling after graphene is adsorbed on the (110) surface of metals from the side views as shown in r) of carbon and metal atoms after optimization. The bond lengths (r) of majority carbon and Ni atoms are less than 2.2 Å, and the bond lengths (r) of minority carbon and Ni atoms are larger than 3 Å. Similarly, the bond lengths (r) of majority carbon and Co atoms are about 2.2 Å, and the bond lengths (r) of minority carbon and Co atoms are larger than 3 Å. According to the new criterion mentioned above, it can be concluded that the adsorption of graphene on the (100) surface of Ni and Co is physical and chemical mixed adsorption. Unlike the graphene–Ni(100) interface and the graphene–Co(100) interface, the bond lengths (r) of minority carbon and Cu atoms are about 2.2 Å, and the bond lengths of some carbon and Cu atoms are close to 3 Å while the bond lengths (r) of other carbon and Cu atoms are larger than 3 Å, which indicates the interactions between carbon and Cu atoms are slightly weaker than those between carbon and Ni (or Co) atoms. That's to say, the adsorption of graphene on the Cu(100) surface is the coexistence of physical adsorption and weak chemisorption. In other words, the adsorption of graphene on the (100) surface of Ni, Co and Cu is all physical and chemical mixed adsorption.An interesting phenomenon is that the graphene sheet shows a large of buckling after graphene is adsorbed on the (100) surface of Ni, Co and Cu from the side views as shown in r) and the relative positions between the carbon and metal atoms, but also have chemical changes, such as the coupling effect between atomic orbitals and charge accumulation between atoms. Therefore, in order to further verify adsorption types of graphene on the metal surfaces, we calculated the projected density of states (PDOS) and the differential charge density in the following paragraphs, respectively.According to the geometric analysis above, the adsorption types of graphene on the metal surfaces are initially determined. Chemisorption process will not only have structural changes, such as the bond lengths (84s2) and Co atom (3d74s2) have open d-shell with two and three unpaired electrons, respectively, while Cu atom (3d104s1) has fully filled d-orbital and half-filled s-orbital, which means Cu atom has only one unpaired electron. Therefore, the interactions between graphene and Ni (or Co) are stronger. Further investigation of the binding mechanism for graphene–metal interfaces was carried out by analysing the projected density of states (PDOS). Notably, as is known to all, the electronic states of graphene become obviously spin-polarized after it is adsorbed on the different surfaces of Ni and Co. Here, the present study only gives the PDOS of spin-up states in order to simplify the analysis. The different interactions between graphene and the metal surfaces mainly arise from the different properties of metals. Ni atom  surface as shown in z orbital and the Ni-dz2 orbital. Still, the electron occupied states of the Ni-dz2 orbital increase significantly above the Fermi energy. Similarly, in the case of the graphene–Co(111) interface, the same conclusions can be drawn according to the projected density of states results in z orbital and the Ni-dz2 orbital as shown in z orbital and the Ni-dz2 orbital form covalent bonds. Above the Fermi energy, the electron occupied states of the Ni-dz2 orbital increase obviously. In addition, for carbon and Ni atoms near the configuration centre, a few overlapping peaks between the C-pz orbital and the Ni-dx2−y2 orbital in the energy range from −3 to 0 eV, which indicates the formation of covalent bonds between the C-pz orbital and the Ni-dx2−y2 orbital. Above the Fermi energy, the electron occupied states of the Ni-dx2−y2 orbital also increase apparently. Similar to the graphene–Ni(110) interface, the same conclusions can also be drawn for the graphene–Co(110) interface according to the projected density of states results in z orbital and the Cu-s orbital in the energy range from −5 to −4.5 eV, −3 to −2.5 eV, −2 to −1.5 eV and −0.5 to 0 eV as shown in z orbital and the Cu-s orbital. Above the Fermi energy, the electron occupied states of the Cu-s orbital increase. Moreover, some overlapping peaks between the C-pz orbital and the Cu-dz2 orbital in the energy range from −5.5 to −3.5 eV and −3 to −1.5 eV as shown in z orbital and the Cu-dz2 orbital form covalent bonds but the amount of overlapping peaks is less than that between the C-pz orbital and the Ni-dz2 (or Co-dz2) orbital, illustrating the interaction between the C-pz orbital and the Cu-dz2 orbital is weaker. Above the Fermi energy, the electron occupied states of the Cu-dz2 orbital also increase remarkably. For carbon and Cu atoms near the configuration centre, a few overlapping peaks are found between the C-pz orbital and the Cu-dx2−y2 orbital as shown in z orbital and the Cu-dx2−y2 orbital form covalent bonds. What's more, the electron occupied states of the Cu-dx2−y2 orbital also increase obviously above the Fermi energy.There exists the strong orbital coupling effect between the carbon and metal atoms after graphene is adsorbed on the Ni(111), Co(111), Ni(110), Co(110) and Cu(110) surfaces, that is to say, the adsorption of graphene on these metal surfaces is chemisorption. In more detail, for the graphene–Ni(111) interface, many overlapping peaks between the C-pz orbital but the projected densities of states of the Cu-s and Cu-dz2 orbitals remain almost unchanged and there are no overlapping peaks found between the C-pz orbital and the Cu-s and Cu-dz2 orbitals as shown in z orbital does not form covalent bonds with the Cu-s and Cu-dz2 orbitals. Still, the electron occupied states of the Cu-s and Cu-dz2 orbitals remain almost unchanged.However, there is no orbital coupling effect between the carbon and Cu atoms after graphene is adsorbed on the Cu(111) surface. Thus, the adsorption of graphene on the Cu(111) surface is only physical adsorption. More specifically, there are slight changes in the PDOS of the C-pz orbital and the Ni-dz2 orbital in the energy range from −5.5 to −1.5 eV, and −0.5 to 0 eV as shown in z orbital and the Ni-dz2 orbital form covalent bonds. Still, the electron occupied states of the Ni-dz2 orbital above the Fermi energy increase obviously. However, for carbon and Ni atoms near the configuration edge, there are no overlapping peaks found between the C-pz orbital and the Ni-dz2 orbital below the Fermi energy as shown in z orbital and the Ni-dz2 orbital. Besides, the electron occupied states of the Ni-dz2 orbital above the Fermi energy also remain almost unchanged. Similarly, as far as the graphene–Co(100) interface is concerned, the same conclusions can be drawn according to z orbital and the Cu-s orbital in the energy range from −5.5 to −5 eV and −2 to −1.5 eV as shown in z orbital and the Cu-s orbital form covalent bonds. Above the Fermi energy, the electron occupied states of the Cu-s orbital increase. What's more, the overlapping peaks between the C-pz orbital and the Cu-dz2 orbital mainly concentrate in the energy range from −4 to −1 eV as shown in z orbital and the Cu-dz2 orbital. Still, the electron occupied states of the Cu-dz2 orbital increase apparently above the Fermi energy. It's worth noting that the amount of overlapping peaks between the C-pz orbital and the Cu-dz2 orbital is less than that of the central carbon atoms adsorbed on the Ni(100) and Co(100) surfaces, which indicates the interaction between the C-pz orbital and the Cu-dz2 orbital is weaker. However, for carbon and Cu atoms near the configuration edge, there are no overlapping peaks found between the C-pz orbital and the Cu-s and Cu-dz2 orbitals as shown in z orbital does not form covalent bonds with the Cu-s and Cu-dz2 orbitals. Besides, the electron occupied states of the Cu-s and Cu-dz2 orbitals remain almost unchanged.Interestingly, there exists the strong orbital coupling effect between the carbon and metal atoms in some parts of the model while there is no orbital coupling effect between the carbon and metal atoms in other parts of the model after graphene is adsorbed on the (100) surface of Ni, Co and Cu. Therefore, the adsorption of graphene on the (100) surface of Ni, Co and Cu is all physical and chemical mixed adsorption. When it comes to the graphene–Ni(100) interface, for carbon and Ni atoms near the configuration centre, there are lots of overlapping peaks found between the C-p−3 e Å−3 and the saturation levels are from −0.01 to 0.01 e Å−3 for −4 e Å−3 and the saturation levels are from −0.001 to 0.001 e Å−3 for The differential charge density has been calculated to further confirm the adsorption types of graphene on the metal surfaces. The differential charge density plots induced by the adsorption of graphene on (111), (110) and (100) surfaces of metals are shown in Notably, there are few reports about the differential charge densities after graphene is adsorbed on the (110) and (100) surfaces of metals. For the graphene–Ni(110) interface as shown in An interesting phenomenon is that the graphene sheet shows a large of buckling after graphene is adsorbed on the (100) surface of Ni, Co and Cu, which makes the interactions between the carbon and metal atoms have some differences. In terms of the graphene–Ni(100) interface as shown in We presented a first-principles investigation of the binding energy, the bond length, the projected density of states and the differential charge density of the graphene–metal interfaces. The interfaces between graphene and low-index metal surfaces such as (111), (110) and (100) surfaces are mainly discussed in this paper. We find that the graphene sheet has a different degree of buckling after graphene is adsorbed on the (110) and (100) surfaces of Ni, Co and Cu. The projected density of states and the differential charge density results confirm the adsorption of graphene on the Ni(111), Co(111), Ni(110), Co(110) and Cu(110) surfaces is chemisorption due to the strong orbital coupling effect and the obvious charge accumulation between the carbon and metal atoms, while the adsorption of graphene on the Cu(111) surface is physical adsorption owing to the absence of the orbital coupling effect and the charge accumulation between the carbon and Cu atoms. Interestingly, the adsorption of graphene on the (100) surface of Ni, Co and Cu is all physical and chemical mixed adsorption because there are the strong orbital coupling effect and the apparent charge accumulation between the carbon and metal atoms in some parts of these surfaces while there are almost no orbital coupling effect and charge accumulation between the carbon and metal atoms in the other parts. The results obtained by the present study are not only expected to explain the adsorption mechanism of graphene on the metal surfaces, but also to provide help for the research of graphene-based composites and carbon nanomaterials.There are no conflicts to declare.


To compare cardio-metabolic, perceptual and neuromuscular responses to an aerobic interval training (AIT) running session, with active (AR) vs. passive recovery (PR).−1·min−1, ⁓ 35 min in 10 km) completed the University of Montréal Track Test (UMTT) and 2 AIT sessions on track in random order, which consisted of 4 × 2 min at 100% of the maximum aerobic speed (MAS), with 2 min of AR at 80% of the velocity associated to the second ventilatory threshold (vVT2), or no exercise . During sessions, oxygen consumption (V̇O2), heart rate (HR), blood lactate [La], rating of perceived exertion (RPE), and countermovement jump (CMJ) were continuously monitored.Eleven well-trained male distance runners  between sessions , although the PR exhibited a greater time spent at peak V̇O2 close to significance . However, the AR elicited a higher mean V̇O2 . The AR favored a lower [La] after sessions  and a higher RPE during sessions . Meanwhile, the CMJ was significantly potentiated during both sessions.There were no differences in time spent in the “red zone” (i.e. > 90% V̇OConsidering that PR elicited lower perceptual loading for a similar cardiorespiratory response, its use would be preferable, at least, for this type of AIT running sessions. Based on the intensity of bouts, HIIT can be performed taxing more the anaerobic  or the aerobic  metabolism (Buchheit and Laursen lim) at the velocity associated to V̇O2max or maximum aerobic speed (MAS) for reaching V̇O2max in AIT running sessions. Thus, prescription of HIIT sessions includes the manipulation of intensity and duration of bouts and recovery intervals for designing appropriate training workloads when looking for specific metabolic and neuromuscular adaptations in the short and the long term  is a method that consists of performing repeated bouts  above the anaerobic threshold, interspersed with pauses, thus allowing the accumulation of more time at a targeted intensity during a single training session   and AR can improve some metabolic and hormonal parameters.Pause duration is determined by the duration of the bout and its intensity, to allow a proper recovery for successfully performing the subsequent work interval, and it is based on the work-to-rest ratio or the return of some physiological parameters  to a set value  for assessing lower limbs neuromuscular function in endurance runners of different levels  for a similar external training load .Therefore, the aim of this investigation was to compare the use of AR vs. PR during a typical AIT running session  performed on a 400-m outdoor track on metabolic , neuromuscular  and perceptual  responses in well-trained endurance runners. Based on previous literature  volunteered for participation. The main characteristics of the participants are shown in Table Our investigation was a cross-sectional study performed along 5 testing sessions separated by a minimum of 48 h see Fig. .Fig. 1ExThe first session was devoted to explain the study procedures and to instruct the participants about experimental conditions, which implied to avoid the ingestion of food, alcohol, caffeine and/or tobacco during the 3 h before evaluations, and not to perform any high-intensity effort during the 24 h prior to each session. Participants were also instructed not to modify their nutrition patterns during the study.The second session consisted of a familiarization with testing procedures. After a standardized warm-up, participants performed 5 continuous CMJs on a force plate  and were also instructed about the Borg’s 6–20 RPE scale.max) calculated according to Tanaka et al.  but with a cyclist setting the running pace  was also recorded.The MAS was considered as the speed attained in the final completed stage, and calculated more precisely according to Kuipers et al. . The tot2 and HR data were automatically filtered with a custom-made software and subsequently averaged to 15-s intervals. The V̇O2max and HRmax were considered as the highest V̇O2 and HR attained in 2 successive 15-s periods, respectively. To confirm a maximal effort, at least 2 of the following criteria were observed in all participants: a) a plateau of V̇O2 despite increasing the running speed (change in V̇O2 ≤ 150 mL·min−1); b) maximum respiratory exchange ratio ≥ 1.1; c) HRmax ≥ 95% age-predicted maximum HR; d) maximum [La] ≥ 8 mmol·L−1; and e) RPE ≥ 17  at 105% of MAS. This verification procedure has been previously described . Participants ran on a 400-m outdoor track following a cyclist who set the running pace, and were instructed to run 2–3 m behind the cyclist and to maintain an even pace for homogenizing drafting between experimental conditions  were carried out in the fourth and fifth sessions under thermo-neutral environmental conditions for all participants (i.e. < 24 °C and < 80% of relative air humidity). The participants performed a standardized warm-up at the beginning of each session. The sessions consisted of 4 bouts of 2 min at 100% of MAS, with a work-to-rest ratio of 1:1. In one session, the recovery period between bouts was passive , whereas in the other session, the rest interval was active  of 5 jumps were recorded for further analysis. Kvert was calculated as the quotient of the change in ground reaction force and displacement of the center of mass . Participants did not attain their V̇O2max nor their HRmax during the experimental sessions, thus peak V̇O2, mean V̇O2, peak HR and mean HR were recorded. The time-to-reach 90% of V̇O2max (TTR90% V̇O2max) and peak V̇O2 (TTRpeak V̇O2), and the accumulated time at or over 90% of V̇O2max (TT90% V̇O2max) and at peak V̇O2  was performed with session and bout as factors. When a significant session × bout interaction was detected, a post hoc t test was carried out with Bonferroni’s adjustment. If normality was rejected, a non-parametric ANOVA type test , whereas for significant pairwise contrasts are presented as Hedge’s g (G) and matched-pairs rank-biserial correlation (r) for parametric and non-parametric comparisons, respectively. The statistical power for the interaction of the 2 × 4 repeated measures ANOVA with a sample size of 11, a correlation among repeated measures of 0.7 and a medium effect size (f = 0.30) is 0.83. Additionally, we calculated the sensitivity of the repeated measures ANOVA to detect this interaction for an alpha level of 0.05, a power of 0.80, a total sample of 11 subjects, and a correlation between repeated measurements of 0.7, obtaining that the test was sensitive to detect a medium effect size (f = 0.29). Main analyses were carried out using the statistical package SPSS version 20.0 , while non-parametric ANOVA type analysis and rank-biserial correlation were performed using the nparLD R and rcompanion software package for R , respectively. The level of statistical significance was set at 0.05.Data are reported as mean ± SD and ranges. The normality assumption for each parameter was verified with the Shapiro–Wilk test. For comparisons between sessions, a paired 2 demands, both in absolute and relative (% V̇O2max) values, total covered distance, time spent in the “red zone”, and time-to-reach the “red zone” during bouts in AR and PR sessions. Higher mean V̇O2 values  and mean V̇O2 relative to V̇O2max  were recorded during the session with AR, whereas higher peak V̇O2 values relative to V̇O2max were obtained during the PR session . Oxygen kinetics during bouts and recovery intervals from the same runner during both sessions is shown in Fig. Table 2 and mean V̇O2 expressed as a percentage of V̇O2max throughout the bouts are represented in Fig. Absolute mean V̇Op = 0.001; G = 0.853, 95% CI ) and peak HR . A significant effect of bout , session  and session × bout interaction  were found for mean HR throughout bouts. Post hoc comparisons detected higher values in PR in comparison with AR for bout 2 , bout 3  and bout 4 . Similarly, mean HR during recovery intervals was significantly higher during AR when compared to the PR session .Recorded HR values during running bouts were significantly higher during AR when compared to PR for mean HR  and session , with no session × bout interaction, was found for [La] recorded 3 min after finishing the last bout during the sessions, with higher values for PR when compared to AR session .A significant effect of bout (p = 0.199), mean jump height (p = 0.729), peak power (p = 0.245), and kvert (p = 0.289). A main effect of bout was only detected for mean jump height  and peak power .Table p = 0.002; pη2 = 0.560) and session , with no session × bout interaction, was revealed with AR showing higher RPE values when compared to PR session .Finally, descriptive and ANOVA results regarding RPE are presented in Fig. 2, mean HR and peak HR levels during running bouts; (2) the peak V̇O2 relative to V̇O2max during bouts was higher with PR; (3) the mean V̇O2 and HR values during recovery intervals were lower with PR; 3) the peak lactate concentration was globally lower with AR; (4) the jump capacity was potentiated, independently from recovery modes; (5) the perceived effort was higher with AR; 6) total covered distance was greater with AR.To the best of our knowledge, this is the first study simultaneously analyzing cardiorespiratory, metabolic, neuromuscular, and perceptual responses during an AIT running session with AR vs. PR intervals. The main findings of the current study are: (1) as expected, the AR elicited higher mean V̇O2 values in the session with AR is not surprising and agrees with previous literature. However, it should be noted that most previous studies used shorter supramaximal bouts  and not all of them were performed with runners. This is an important consideration as the training session selected, in terms of intensity and volume, could be considered more appropriate for the level of the recreational runners of our study . In this regard, O’Brien et al. (2 (3200 ± 661 mL/min) and more time spent in the “red zone” (4.47 ± 3.55 min) during the session than 1-min bouts  or continuous running (2909 ± 584 mL/min) of equivalent external load. On the other hand, Seiler and Sjursen  when performing 12 self-paced bouts of 2 min interspersed with 2-min self-paced recovery intervals compared to 1-min bouts in a sample of well-trained runners. The higher mean V̇O2 values attained during bouts (ranging from 81 to 84% V̇O2max in both conditions) could be explained by the differences in volume and intensity of our protocol in comparison to that used by Seiler and Sjursen  were similar to those obtained in our study (ranging from 95 to 98% VO2max in both conditions).The finding of greater mean V̇On et al.  demonstr Sjursen  reported Sjursen   during the verification phase. In this sense, we found non-significant differences between experimental sessions regarding TT90% V̇O2max, TTpeak V̇O2, TTR90% V̇O2max and TTRpeak V̇O2. However, and although these variables were quite similar for both conditions, we found longer TTpeak V̇O2 in the PR session with confidence interval of the effect size not including null effect . This phenomenon could be explained by a more pronounced increase in V̇O2 rate for the PR condition due to a greater V̇O2 amplitude , resulting in a steeper V̇O2 slope . However, this increment in total running distance should be cautiously interpreted, since it was performed at low intensities . In this sense, one must consider that total external training load  will be greater for AR when compared to PR sessions. However, targeted training intensities during work intervals were identical for both conditions. Thus, from a practical point of view, the distance accumulated during AIT sessions with AR should be considered in the computed training volume. From the current results, it can be suggested the use of PR when targeting for accumulating a greater volume of high-intensity work intervals, whereas AR could be recommended for maximizing physiological stress during AIT running sessions of moderate volume. This suggestion is based on the lower mean HR and V̇O2 values recorded during the PR intervals when compared to the active ones. Meanwhile, the correspondence between V̇O2 and HR responses during running bouts does confirm the validity of HR as a simple and valid monitoring tool to verify the purported physiological adaptations during HIIT sessions.Taking together, this idea supports the previous recommendations of Hill and Rowell  of using2. These results are in accordance with previous studies which also demonstrated a better lactate clearance during AIT running sessions when active recovering at velocities close to the anaerobic threshold  initially and perceived as “very hard”  by the end of the workout  and other AIT running sessions with different schemes and work-to-rest ratios.For the first time, we have concurrently analyzed the cardio-metabolic, neuromuscular and perceptual response of AIT running sessions completed on a 400-m outdoor track at 100% of MAS but differing in recovery mode. The practical applications from the current results for coaches, sport scientist and athletes are different regarding training objectives. Recreational runners as those of our study could benefit from AR during AIT running sessions when looking for a higher physiological stress. In contrast, PR may elicit a lower physiological stress for a similar external training load and, therefore, could be preferable for high-volume AIT running sessions. However, it is still to be solved if the same picture would be evident with a longer session with more running bouts. Further, longitudinal studies are guaranteed to better understand the adaptations in the long-term to these recovery modes during AIT running sessions.


This study demonstrates a novel and scalable method to synthesize multilayer graphene using CO2 from ambient air at 1 g/kWh electricity, potentially allowing for multilayer graphene production by the ton. The approach creates opportunities to synthesize multilayer graphene particles with defined properties through a careful control of the synthesis parameters for tailored applications.Graphene produced by different methods can present varying physicochemical properties and quality, resulting in a wide range of applications. The implementation of a novel method to synthesize graphene requires characterizations to determine the relevant physicochemical and functional properties for its tailored application. We present a novel method for multilayer graphene synthesis using atmospheric carbon dioxide with characterization. Synthesis begins with carbon dioxide sequestered from air by monoethanolamine dissolution and released into an enclosed vessel. Magnesium is ignited in the presence of the concentrated carbon dioxide, resulting in the formation of graphene flakes. These flakes are separated and enhanced by washing with hydrochloric acid and exfoliation by ammonium sulfate, which is then cycled through a tumble blender and filtrated. Raman spectroscopic characterization, FTIR spectroscopic characterization, XPS spectroscopic characterization, SEM imaging, and TEM imaging indicated that the graphene has fifteen layers with some remnant oxygen-possessing and nitrogen-possessing functional groups. The multilayer graphene flake possessed particle sizes ranging from 2 µm to 80 µm in diameter. BET analysis measured the surface area of the multilayer graphene particles as 330 m The pro11 cm−2,  displays11 cm−2, ,6,7,8,9 /mK [2/g  and expe2/g [2/g ,13.The exact effect of these properties relates to the structural defects and functionalization of the graphene sheet ,13, whic2. This process differs from other CO2-based graphene synthesis methods in that the CO2 used in this process is directly sequestered from ambient air rather than originating from treated or purified CO2 stored in tanks. This allows for the design of continuous flow systems that enable the method to be scalable for commercial applications under optimum economy. Furthermore, the electrolytic recombination is done with graphene flakes in ethanol suspension compared to prior works, which exfoliate graphite rods using electrolysis. This method offers opportunities to recycle all of the generated chemical waste back into the process. This saves processing costs and allows for environmentally friendly method of production.In this work, we describe a novel multilayer graphene synthesis process using COVariations in the production method can result in graphene predisposed to different structural defects and functionalization, which make it paramount to examine the properties of the multilayer graphene produced by this novel method.2 solution; (2) heating an aqueous monoethanolamine solution; and (3) collecting the released CO2 containing magnesium element for graphene production. The multilayer graphene product was characterized via Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller analysis (BET), and transmission electron microscopy (TEM). These analyses were used to study the number of layers present, the functionalization, and the surface area properties of the multilayer graphene product.The novel method for synthesizing multilayer graphene sheets from carbon dioxide involves the ignition of magnesium and carbon dioxide sequestered from air, followed by refinement in an aqueous suspension of exfoliated graphene . The priThe novelty of this method is that it was designed as a scalable process to be readily applied to an industrial setting with no environmental waste rather than a laboratory setting with small-scale yields. The inventor of this method chose magnesium metal as opposed to other reducing metals such as sodium because the equipment available is more readily designed for higher combustion heats and is generally more stable than sodium. The inventor of this method also chose MEA to sequester carbon as opposed to other options—zeolites, metal–organic frameworks, mesoporous silicas, hydrotalcites, or activated carbons—because monoethanolamine (MEA) is easier to integrate into continuous flow systems. MEA also has the advantage of being continuously recycled, meaning that it is not wasted in the process. All other waste streams in the process are salts that can be dried or refined back to their original constituents and recycled into the proposed method using similar continuous flow systems. It should be noted that the goal of this research is to prove the efficacy of already patented technology, and not to dispute against other methods with hypothetical alternative chemicals.(1)Sequester of carbon dioxide gas from ambient air:2 solution (30%) is heated to ~35 °C to release the adsorbed carbon dioxide, which is then stored in a collection tank.The sequester of carbon dioxide gas from ambient air comprises several steps, as shown in (2)Synthesis of multilayer graphene sheets from carbon dioxide gas:The synthesis of multilayer graphene sheets from carbon dioxide gas comprises several steps, as shown in Magnesium chloride, water, and graphene flakes are formed by washing the graphene flakes and magnesium oxide with aqueous hydrochloric acid solution, as shown in the following reaction.The graphene flakes are then exfoliated in an ammonium sulfate solution (0.1 M with pH 6.5–7) and tumbled in a blender for several hours. Finally, the sheets are washed and dried.(3)Analytical characterization of the multilayer graphene material:−1 and a 20 × 40 N microscopic objective. The laser power had a variable range of 200 mW and readings, which were taken at approximately 175 mW. The wave numbers measured were 300 cm−1 to 4000 cm−1. Only the range relative to characterizing graphene is presented. The ATR-IR spectra of the multilayer graphene were measured with a FTIR spectrometer  with a diamond ATR attachment allowing a spectral resolution of 2 cm−1 in the range of 4000–600 cm−1. X-ray photoelectron spectroscopy  was performed. Wide-energy range survey spectra (0–1350 eV) were acquired for qualitative and quantitative analysis . An assessment of the chemical bonding of the identified elements was accomplished by collecting core-level spectra over a narrow energy range . SEM  was performed. BET  analysis was performed. For the initial gas desorption, the samples were heated to 200 °C at a heating rate of 5 °C/min over a period of 360 min. The absorbing gas was nitrogen . The absorption and desorption curves were obtained from the unit and the samples were cooled with liquid nitrogen. The porosity of the sample was calculated using non-local density functional theory with slit pores for nitrogen gas on carbon. Scanning transmission electron microscope analysis  was performed with a field emission gun (FEG) operating at 100 kV to demonstrate the number of layers of graphene.Raman spectroscopy  was performed with a 532 nm laser with a resolution of 8 cm−1 denotes the D peak; the peak at ~1571 ± 2 cm−1 denotes the G peak; and the peak at ~2674 ± 3 cm−1 denotes the 2D peak. The D peak was not analyzed beyond recognizing that its presence indicated that structural disorders were present in the multilayer graphene [−1 and at ~2635 cm−1). The presence of this sub-peak indicates that the multilayer graphene has more than ten layers [graphene ,17. Bothgraphene ,19,20,21graphene ,19,20,21n layers ,17, but n layers ,17.G/I2D) was found to be 1.28. Previous work has modeled intensity ratio as a function of the number of graphene layers using an exponential equation; as the number of layers approaches infinity, the limit of this equation is 1.33 [From  is 1.33 . Due to −1 is assigned to CO2. The broad peak around 3630 cm−1 is attributed to -OH stretching [−1, respectively [−1 were associated with C–O in carboxyl or hydroxyl groups, -C-O-C, and C-O groups [In retching . The -C-ectively . Bands aO groups . These rXPS was conducted to further confirm the chemical composition of the graphene. As shown in In 2/g. Since the presence of the oxygen functional groups were shown in the FTIR spectrum, a comparison to the measured surface areas of reduced multilayer graphene oxides in other studies [In  studies ,28,29,30Commercial viability analysis of the synthesis process: The greatest limiting factor in the process is the electrical requirement per material input. At 400 ppm of carbon dioxide in ambient air, it is estimated that approximately 64 cubic meters of air would need to be processed per gram of carbon. At an Ecophene facility, with a production capability of 4.5 kg per month, the current electrical requirements from sequestered carbon dioxide in ambient air to multilayer graphene powder require about 1 kwh per gram of multilayer graphene. This data is for equipment having a maximum output of up to 10 kg per month; thus, with larger equipment and more sophisticated autonomous throughput systems, the electrical cost per gram is expected to decrease significantly. The method used reduced labor costs since a less-skilled workforce is required for operation and the potential for automation labor costs can almost be eliminated. Finally, the current production system has a relatively high material loss of ~3%. With more sophisticated systems, this material loss can be significantly reduced. The combination of these factors means that multilayer graphene can be reliably produced at about 20–25% cheaper than the market value of $70/g.Environmental Implications: The novelty of the method used demonstrates a practical method of converting atmospheric carbon dioxide, the primary greenhouse gas responsible for anthropogenic climate change, into useful raw material with various benefits. Although it may not be enough to remove all of the excess carbon dioxide responsible for anthropogenic climate change, it demonstrates that atmospheric carbon dioxide mitigation can be achieved in a cost-effective and environmentally beneficial way. With further investigation, the production cost could be further reduced with quality improvement of the material.2/g, and the pore distribution indicated ~51% of the pores between 0.8 nm and 5 nm in diameter. This work demonstrates a novel and scalable synthesis method to produce multilayer graphene from CO2 at 20–25% lower cost/gram with various physiochemical features that can be potentially tailored for a wide range of applications. Additionally, this synthesis method was developed to have a net-positive impact on the environment. The recovery of CO2 from ambient air reduces greenhouse gases in the atmosphere, and this reduction contributes to curtailing climate change. Furthermore, the chemical waste generated by the process can be recovered and recycled; this lends itself to the sustainability of the method.Eleven Raman spectra of the multilayer graphene sample obtained from different points were presented, and a view of the 2D peak from one of the spectra after baseline removal was shown. Analysis of the data indicated that the multilayer graphene sample composed of more than ten layers, structurally disordered and functionalized. The TEM image of the multilayer graphene indicated a thickness of 15–16 layers. The FTIR spectra showed the presence of C-O-C, -C=O, C-O, and OH functional groups in the sample; the XPS spectra confirmed the presence of these functional groups as well as nitrogen-containing groups (pyridine and pyrrolic-N). These were introduced during their synthesis. The absorption-desorption isotherm of the multilayer graphene indicated a measured surface area of ~330 mMultilayer graphene used in this manuscript is based on the patented technology. Alvarez, L. “Apparatus, System and Method for Conversion of Atmospheric Carbon Dioxide to Graphene”. United States Patent Number: US 11,192,790 B2, 7 December 2021.


The Coulomb excitations of charge density oscillation are calculated for a double-layer heterostructure. Specifically, we consider two-dimensional (2D) layers of silicene and graphene on a substrate. From the obtained surface response function, we calculated the plasmon dispersion relations, which demonstrate how the Coulomb interaction renormalizes the plasmon frequencies. Most importantly, we have conducted a thorough investigation of how the decay rates of the plasmons in these heterostructures are affected by the Coulomb coupling between different types of two-dimensional materials whose separations could be varied. A novel effect of nullification of the silicene band gap is noticed when graphene is introduced into the system. To utilize these effects for experimental and industrial purposes, graphical results for the different parameters are presented. A huge number of researchers from various disciplines have been showing their interest in new materials, silicene especially, after the development of its fabrication process in 2012 . Their rBoth silicene and graphene were studied in parallel. The former has a buckled crystal geometry, whereas the latter has a honeycomb planar geometry. Due to this, differences arise between them. Ab initio calculations showed that the bandgap of silicene is electrically tunable ,5,6, whiSeveral investigations have been carried out on both graphene and silicene with respect to transport phenomena ,14,15,16Recently, Dong et al.  studied The plasmon mode is tunable by the thickness of the substrate and the variation of material behavior. We first determine the surface response function of the structure, the same technique used recently by Gumbs et al. ,53, whicWe have organized the rest of our paper as follows. In In this section, we analyze the plasmonic behavior of the heterostructure consisting of graphene and silicene together for which we employ the low-energy form of the Hamiltonian near the K point in the Brillouin zone. One significant difference between the Hamiltonian of graphene and silicene is that a small band gap, K and We now briefly describe the case pertaining to silicene whose Hamiltonian in the continuum limit is given by:leys, vF≈×105 m/s silicene , kx and e system  for intr100 meV) . The lasgiven by :(2)H^σξ=This gives the low-energy eigenvalues as:The low-energy model Hamiltonian for monolayer graphene is similar to that in Equation  with thegiven by :(4)H^=ℏvq is the wave vector and e is the electron charge. The polarization function is an important quantity in calculations of the transport, collective charge motion and charge screening properties of the material. In the one-loop approximation, the polarization function for gapped graphene is given by [Considerable work has been completed on the dynamical properties involving the use of the dielectric function  systems ,58,59 un systems ,61, the  systems  and the given by :(6)Π0, which is reflected in their energy dispersions though the presence or absence of a band gap. The two layers could also have different or equal doping levels (Fermi energies). By employing the boundary condition of continuity of the electrostatic potential and the discontinuity of the electric field across the interface separating two media, we solved for the various coefficients appearing in the potential. Consequently, the result for the surface response function d is the thickness of the substrate. This substrate thickness is in the order of the wavelength of light considered, for a visible light it could be of the order of a few hundred nanometers. For a thick substrate, the thickness could go up to micrometer in size, and accordingly, the plasmonic mode is modified. The plasmon dispersion equation is obtained from the solutions of Here, ading to:g=1Dquation =Equation .We now turn to a critical issue in this paper, which concerns the rate of damping of the plasmon modes by the single-particle excitations. If this rate of damping for a plasmon mode with frequency Therefore, setting the function in Equation  equal toWith these formal results, we now evaluate the plasma spectra for a double layer heterostructure. The expression shows the dependence of In our numerical calculations, energy is scaled in units of Going next to the case when we have a structure with two graphene layers together separated by various distances, a set of plots  and optical (higher frequencies), or as in-phase and out-of-phase . The numWe should also mention that the frequency of the optical plasmon branch depends on the distance between the layers. One can easily verify this by analyzing how far the branch moves from the main diagonal To extract more information about the plasmonic behavior, in A special effect of overcoming the single-particle excitation region of silicene by the single-particle excitation region of graphene is observed, which causes the shortening of the plasmon branches that used to be there for the silicene–silicene structure. As soon as the plasmon branch reaches the particle-hole mode region, the plasmon mode decays by replacing one silicene layer with a graphene layer in the silicene–silicene structure. The effect, due to the band gap in silicene, is just nullified. In other words, the plasmon modes in the regime, where they used to have plasmon modes before, now do not have them, because the plasmon mode decays into the particle-hole mode of graphene. Furthermore, the result of adding a substrate between the silicene and graphene layer is illustrated in panel (b) of The results in equation , which iThese new effects on the plasmon branches in this type of structure were not reported previously. Results of this type help develop electronic and quantum computing devices where knowledge of the plasmonic behavior of materials and their damping nature is very essential.In summary, we have investigated the key properties of the plasmonic mode and damping for different combinations of graphene and silicene layers. The effect of the addition of substrate in between the two layers is further analyzed. This resulted in the development of a novel technique of tuning the plasmon excitation mode associated with the two dimensional systems. In our system, a complete new plasmon branch emerges from the bulk plasmon frequency, this would be very helpful in engineering modern computing devices.Another discovery we have from this study is the disappearance of the lower plasmon branch and the suppression of the silicene band gap effect. Along with the study of interesting features in the plasmon modes, we have also developed an approach for calculating the decay rates for the plasmons due to Landau damping by the particle-hole modes.The principal goal of our investigation and the main results of our work are concerned with the understanding of plasmonic nature and analyzing their Landau damping rates in a multi-layer structure. In contrast to Ref. , which iAdditionally, our results infer that the number of plasmon branches emerging from the origin can be varied by choosing the number of the 2D layer. In brief, we can say that our study gives an important idea about the plasmonic behavior of a graphene–silicene-based heterostructure, which would be very helpful in carrying out further studies of other types of heterostructure, including a variety of low dimensional materials.