Hand, foot and mouth disease (HFMD) is a growing threat to children's health, causing a serious public health burden in China. The relationships between associated meteorological factors and HFMD have been widely studied. However, the HFMD burden due to relative humidity from the perspective of attributable risk has been neglected. This study investigated the humidity-HFMD relationship in three comprehensive perspectives, humidity-HFMD relationship curves, effect modification and attributable risks in the Sichuan Basin between 2011 and 2017. We used multistage analyses composed of distributed lag nonlinear models (DLNMs), a multivariate meta-regression model and the calculations of attributable risk to quantify the humidity-HFMD association. We observed a J-shaped pattern for the pooled cumulative humidity-HFMD relationship, which presented significant heterogeneity relating to the geographical region and number of primary school students. Overall, 27.77% (95% CI 25.24–30.02%) of HFMD infections were attributed to humidity. High relative humidity resulted in the greatest burden of HFMD infections. The proportion of high humidity-related HFMD in the southern basin was higher than that in the northern basin. The findings provide evidence from multiple perspectives for public health policy formulation and health resource allocation to develop priorities and targeted policies to ease the HFMD burden associated with humidity. It mostly occurs in children under 5 years old. The disease is mainly transmitted via the fecal–oral route, followed by the respiratory route2. The clinical symptoms in most patients are mild, self-limited and generally tend to disappear or decrease in 7–10 days. Some patients, however, may rapidly develop severe complications, such as central nervous system damage, cardiopulmonary failure, and even death3. In the past few decades, several HFMD epidemics and outbreaks have been reported in the Asian-Pacific region6. In China, HFMD, a primary infectious disease, has the highest annual incidence, ranging from 37.01/100,000 to 205.06/100,0007, compared with all the other notifiable infectious diseases . Moreover, since 2008, the number of reported HFMD cases has been increasing dramatically, and the cumulative number has reached over 22 million, surpassing the numbers of cases in most Asian-Pacific countries8. Based on the severity of the HFMD situation and its growing threat to children, HFMD has recently become an important public health issue that has attracted much attention.Hand, foot, and mouth disease (HFMD) is a common acute infection caused by a series of enteroviruses and coxsackie viruses15. The majority of studies focused on exploring the impacts of temperature and relative humidity on HFMD infections. Numerous studies analyzed and found a consistent relationship between temperature and HFMD. However, for the effects of relative humidity, the existing literature has suggested inconsistent results. For example, early studies generally showed a simple linear relationship. A16 study in Beijing showed that relative humidity was negatively associated with HFMD infections. In contrast, other studies from Thailand17, the Mekong Delta region in Vietnam18, Taiwan19, Shandong20 and Guangdong21 showed positive associations. Recently, epidemiologists have shown increasing interest in explicating potential complicated nonlinear impacts of relative humidity. A study in Hong Kong22 revealed a J-shaped relationship, while another study in Guangdong23 found an increasing risk of HFMD with relative humidity, with 86.9% relative humidity at the peak of the exposure–response curve. The heterogeneity of results might be associated with the differences in geographic locations, socioeconomic statuses and health services.Many epidemiological studies have revealed that meteorological factors tend to have complex nonlinear and delayed effects on HFMD24. Moreover, the impacts of relative humidity on HFMD were primarily quantified by measuring risk ratios  in published studies27, and the extra burden of HFMD attributed to exposure was not adequately assessed. Risk ratios and similar effect estimates are more difficult to understand from a public health perspective, while attributable numbers or fractions are easier to comprehend. Thus, calculating attributable risk indexes, such as the attributable number (AN) or attributable fraction (AF), is appropriate to reflect the overall disease burden associated with exposure factors and provide new evidence for effective interventions, health resource allocation, and predictions of the effects of climate change. Very few studies have explored the morbidity burden of HFMD infection attributable to relative humidity. To the best of our knowledge, no studies have focused on revealing the attributable risk in consideration of the possible complex nonlinear impacts and delayed impacts in the humidity-HFMD relationship. Therefore, the present study quantified the attributable risks of HFMD due to relative humidity based on the complex non-linear and lagged exposure–response relationship in the Sichuan Basin, an area with diverse climatic and socioeconomic characteristics among cities, which provides a more comprehensive and rational insight into the association.Most previous studies constructed single-city time series regressions with different modeling approaches and parameter determinations, which limit the comparability of city-specific findings. Diverse city-level factors may also cause inconsistent results across different cities, limiting generalizability. Therefore, a multicity distributed lag nonlinear modeling approach should be developed in which relationships in each city are assessed, and then the city-specific effects are pooled to explore the source of the heterogeneous resultsThe Sichuan Basin was chosen as our research area based on the following two reasons. First, the Sichuan region has been experiencing a severe HFMD epidemic since 2009, and the annual incidence continues to increase. In 2018, more than 13 thousand cases were reported, which was 6 times higher than that in 2009. Second, the Sichuan Basin has a complex terrain, and the numerous rivers lead to high and variable air humidity. Moreover, 17 cities in the Sichuan Basin have variable degrees of economic development, demographic characteristics, and health services. These factors may modify the effect of relative humidity on HFMD.We thus aimed to analyze the time series association of relative humidity with HFMD in 17 Sichuan Basin cities between 2011 and 2017, explore the modification effects of city-level variables, and quantify the infection burden of HFMD attributed to relative humidity to narrow the knowledge gap left by previous studies.A total of 427,788 HFMD cases were reported in the 17 cities in the Sichuan Basin between 2011 and 2017. On average, the daily number of reported HFMD cases was 10 (range 0–33). According to city-specific total numbers of reported HFMD cases, Chengdu, Meishan, Mianyang, and Deyang were the top 4 cities with the highest numbers of cases  to 52.5% and 51.1%, respectively. We found no significant modification effects for other variables . Figure Table The estimated city-specific ANs and AFs for total relative humidity and high relative humidity above the 75th percentile and low relative humidity below the 25th percentile are shown in Fig. The results quantified the influence of relative humidity on HFMD in children in the Sichuan Basin from multiple perspectives. This research has two main strengths. To our knowledge, this is the first study conducted in a basin region with diverse climatic and socioeconomic characteristics using a multicity statistical analysis strategy to explore the association between relative humidity and HFMD in children. The complex nonlinear and delayed impacts of relative humidity were firstly included to measure the risk of HFMD in children attributable to relative humidity.28 also suggested a monotonic increasing curve in southwestern China. Although research on the exact mechanisms is lacking, some evidence suggests that relative humidity may influence HFMD through several complex pathways. First, enteroviruses, the pathogens of HFMD, can survive in the environment for a period of time, increasing the chance to infect vulnerable individuals29. Relative humidity may impact the survival time and reproductive capacity of enteroviruses, thereby increasing or decreasing the chance of contact30. Second, on days with high relative humidity, infected people may excrete more enteroviruses into the environment31, which could easily attach to the small particles on the surface of toys or in the air32. This process could lead to the accumulation of the virus in the environment, thus accelerating the spread of HFMD. Third, humoral or cellular immunity could be affected by climatic factors33, especially in children with relatively immature immune systems and poor self-care abilities34. As relative humidity increases, body sweats and metabolism are restricted, making children more susceptible to the enteroviruses that cause HFMD. Therefore, the impact of relative humidity should be taken into account for future control and prevention policies for HFMD.This study evaluated the effects of relative humidity in 17 Sichuan Basin cities through a multicity two-stage time series modeling strategy. Consistent with previous studies in this region, this study found an approximate nonlinear J-shaped relationship, in which the risk of HFMD increased with increasing relative humidity. A study in mainland China2 statistics from the Cochran test show moderate heterogeneity among the variables, which is consistent with most previous studies23. Among all city-level variables, geographical region and the number of primary school students remained the two main potential effect modifiers leading to significant heterogeneity. Increased susceptibility to HFMD has been identified in the southern basin, which has high relative humidity. A previous study conducted in Sichuan Province suggested that the dominant HFMD serotypes also showed obvious regional differences, which varied from 2011 to 201735. Different strains of pathogens may have different behaviors due to relative humidity30. In the southern basin, under the condition of high relative humidity, pathogens may be able to thrive depending on humidity, resulting in longer survival times, and have stronger infectiousness. Further research is required to investigate regional differences in pathogen-specific performance depending on meteorological factors in the time scale. Moreover, previous virological studies reported that temperature plays an important role in the survival of enteroviruses and can affect the daily activities of the host and the excretion of enteroviruses36. The southern basin tends to experience relatively high temperatures, increasing the effect of high relative humidity on HFMD38, which may be another mechanism of the impact of relative humidity on HFMD. Similar to the findings of the present research, a study of 8 cities in Guangdong Province23 found that geographic location indicators, such as longitude and latitude, partially explained the heterogeneity of results among cities. Similarly, the effects of regional differences in humidity on HFMD were also observed in the second peak, especially in northwest and south regions, which show increased susceptibility to HFMD. More comprehensive stratified analyses are still needed to examine the season-stratified effects of meteorological factors such as relative humidity on childhood HFMD.In this study, a distributed lag nonlinear model (DLNM) combined with a multivariate meta-regression model was applied to conduct a unified analysis of multicity data to eliminate the possible impact of heterogeneity due to methodology. The I39. On the other hand, children in developed areas with better infrastructure and public transport may also tend to engage in more outdoor activities and have more social contact, thus causing higher HFMD burdens40.On the other hand, primary school students, the crucial HFMD-susceptible group, gather in fixed public places, such as schools, for a long time. More students results in closer the contact between susceptible students and infected students, consequently promoting the spread of HFMD. Notably, GDP growth was also fairly close to reaching significance. On one hand, people who are more economically well off may have greater health awareness and a limited need for extra day care, with higher socioeconomic status therefore corresponding to lower susceptibilityOur results revealed that humidity above the 75th percentile of relative humidity accounted for more than 50% of humidity-related HFMD cases, which is far higher than the proportion of 6% with humidity below the 25th percentile of relative humidity, indicating that the relative humidity-related attributable risk of HFMD primarily depends on relatively high humidity. Therefore, policymakers should increase parents’ awareness of the adverse health effects of wet environments and allocate additional health resources to implement effective public health interventions, especially for children in the northern basin. In addition, the AF attributable to relative humidity varied from 9.72 to 43.27% among cities. In general, the AF associated with high relative humidity in the northern basin was higher than that in the southern basin, while the AF of low relative humidity was higher in the southern basin. Compared with children in the southern basin, children in the northern basin are more susceptible to HFMD under high relative humidity conditions. One explanation is that people change their physical appearance and individual behaviors to adapt to local environmental conditions. The popularity of humidity control devices can help partly reduce the impact of high and low humidity on HFMD infections in children.41. Second, this study took city-level geographic, demographic, economic, health resource and traffic variables into account, but they accounted for only a small part of the heterogeneity. Some other important meta-predictors may also be related to HFMD, such as vegetation coverage and prevention and control measures for infectious diseases, which may partly explain the heterogeneity. However, due to limited access to data, these factors were not considered in this study. In addition, modeling the relationship between weather and infectious diseases while controlling residual autocorrelations by including an autoregressive term of past case counts into time-series regression models remains controversial. Some studies believe that lagged case counts are needed to control autocorrelations42, while other studies argue that including lagged case counts into the causal path of the overall weather-lag-disease relationship would result in underestimation of the true relationship44. In this study, we did not include the autoregressive term in the base model to avoid a possible downward bias.This study has several limitations. First, this was an ecological study, and the meteorological data were obtained from fixed monitoring stations rather than the real exposure of individuals. Therefore, measurement error is inevitable and may be randomly distributed, consequently underestimating the humidity-HFMD associationIn conclusion, this study reveals a J-shaped relationship between relative humidity and HFMD in the Sichuan Basin, though the relationship varied from city to city. Geographic region and number of primary school students were the two primary effect modifiers. High relative humidity contributed to most of the HFMD burden attributable to relative humidity. Our findings can help policy makers and parents improve the negative health effects of low and high relative humidity on child morbidity due to HFMD. These research findings may also provide an important basis from multiple perspectives for relevant public health decision-making and allow the allocation of additional health resources to mitigate the adverse health impacts of relative humidity, especially for people living in regions with relatively high humidity.2. Seventeen cities with a population of over 82 million are present in Sichuan Basin (according to 2014 demographic data). According to the national standard of meteorological and geographic division, the Sichuan Basin is divided into 4 regions .The Sichuan Basin, located in southeastern China, covers a total of 185,757 km46. City-specific clinical HFMD case information, including basic demographic information , disease information  and report information , was obtained from the China Information System for Disease Control and Prevention in the Sichuan Basin from 1 January 2011 to 31 December 2017. The China Center for Disease Control and Prevention assured and assessed the quality of the dataset. Among the dataset, children aged 0–15 years accounted for more than 99.7% of HFMD cases. Therefore, we selected reported HFMD cases in children under 15 years old throughout the Sichuan Basin for further analysis. Finally, we aggregated all cases under the age of 15 with symptom presentation into the daily HFMD counts at the prefecture level in 17 cities in the Sichuan Basin.HFMD was listed as a class “C” notifiable disease for reporting and management in China in 2004. Each HFMD case clinically diagnosed according to a standard guideline should be reported online within 24 h47. For cities with more than one meteorological monitoring station, we selected data from the station closest to the city geometric center14.Daily meteorological surveillance data, including the mean relative humidity (%), mean temperature (℃), minimum temperature (℃), maximum temperature (℃), mean atmosphere pressure (hPa), mean wind velocity (m/s) and sunshine duration (h), were collected from the China Meteorological Data Sharing Service System. For humidity, temperature, atmosphere pressure and wind velocity, the missing values were imputed using linear interpolation; for sunshine duration, the missing values were filled by zero depending on the nature of meteorological data. However, the missing data issue should be negligible given the very small proportion of missing values (approximately 0.1%) and the high quality of the monitoring data. For cities with no meteorological monitoring stations within the city administrative boundaries, data from the station in adjacent cities closest to the city center were usedWe obtained city-level geographic characteristics (region), demographic characteristics , economic characteristics (gross domestic product (GDP) per capita and GDP growth), health resource characteristics  and traffic characteristics (travel passengers) from the China City Statistical Yearbooks from 2011 to 2017. For each city, the arithmetic averages of all the city-level variables were calculated as a proxy for socioeconomic differences among cities in the Sichuan Basin. In the second-stage analysis, these average variables were added as modifiers to explore modification effects on the humidity-HFMD relationship.We used a two-stage multicity time series analysis strategy to analyze data from the Sichuan Basin from 2011 to 2017. First, a distributed lag nonlinear model (DLNM) was applied for each city’s data to obtain city-specific effect estimates. Second, we applied a multivariate meta-analysis to combine the effect estimates obtained from the first-stage analysis, and city-level variables were included to further investigate whether they could explain the heterogeneity between cities. Then, the risk of HFMD attributed to relative humidity was calculated by a backward perspective method.48. A cross-basis function was used to describe the two-dimensional exposure-lag-response association. We used natural cubic splines for the effects of relative humidity with 3 degrees of freedom (dfs) and natural cubic splines for lag effects with 4 dfs. Based on the parametrization in previous studies37 and the incubation period (approximately 3–5 days)46, we chose 3–17 days as the lag range to study the lag structure of the humidity-HFMD relationship. Mean temperature, atmospheric pressure, sunshine duration, and wind velocity were important confounding factors in the humidity-HFMD relationship. Therefore, we controlled for temperature by calculating simple moving weighted averages in the same lag range as relative humidity and a natural cubic spline with 3 dfs. The other three factors were controlled by calculating exponential moving weighted averages in the same lag range as relative humidity. A natural cubic spline with eight dfs per year was used to control for seasonality and long-term trends of HFMD. The day of week and holidays were set as two indicator variables in the model.For each city, we constructed a DLNM with a quasi-Poisson distribution to measure the nonlinear and lag relationship between relative humidity and HFMD50. Based on the intercept-only model, we individually included city-level variables in the intercept-only model to construct univariable meta-regression models to explore effect modifications. The likelihood ratio (LR) test was applied to test the significance of these variables. We identified and quantified residual heterogeneity through multivariate extension of the Cochran Q test and I2 statistic50. Stratified analyses were conducted for the first peak (April–July) and the second peak (September–December) to further examine whether regional differences in humidity effects on HFMD existed in two peaks periods.For the second-stage analysis, to obtain the overall effect estimates of relative humidity in the Sichuan Basin, we reduced the estimates from DLNMs and then fitted an intercept-only multivariate meta-regression model51, was considered the counterfactual exposure reference to calculate the infection burden of HFMD attributable to relative humidity. City-specific minimum-morbidity relative humidity was identified from the city-specific exposure–response relationship curve. We adopted a backward perspective considering that current risk was the accumulation of the exposure effect of a previous period52. We summed the contributions from all days in the series to compute the total number of HFMD cases attributed to relative humidity. The ratio of the number to the actual total cases in the corresponding city or region is the AF. We calculated the components attributable to high relative humidity above the 75th percentile and low relative humidity below the 25th percentile. Empirical confidence intervals (eCIs) were derived by Monte Carlo simulations52.The minimum-morbidity relative humidity, corresponding to the relative humidity associated with the minimum morbidity risk between the 5th and 95th percentiles12 and prior knowledge (see more details in Online Appendix Text Considering the systematic sensitivity analysis strategy proposed by XiaoAll HFMD surveillance data were collected from the China Information System for Disease Control and Prevention. This study was analyzed at the aggregate level and the research protocol was approved by the institutional review board of the School of Public Health, Sichuan University. All methods were carried out in accordance with relevant guidelines and regulations. All of the patients’ records were anonymized and deidentified, thus the need for informed consent was waived by the Ethics Review Committee of the Sichuan Provincial Center for Disease Control and Prevention.Supplementary Information.


Device performance was demonstrated by touch sensing and thermal distribution mapping-based shape detection. Sensor output voltage in the latter application was on the order of 300 μV with a signal-to-noise ratio (SNR) of 35, thus enabling accurate detection of objects of different shapes and sizes. The results imply that films based on multilayer graphene ink are highly suitable to thermoelectric sensing applications, while the ink phase enables facile integration into existing fabrication processes.Emergent applications in wearable electronics require inexpensive sensors suited to scalable manufacturing. This work demonstrates a large-area thermal sensor based on distributed thermocouple architecture and ink-based multilayer graphene film. The proposed device combines the exceptional mechanical properties of multilayer graphene nanocomposite with the reliability and passive sensing performance enabled by thermoelectrics. The Seebeck coefficient of the spray-deposited films revealed an inverse thickness dependence with the largest value of 44.7 μV K Temperature sensing is pivotal in a wide variety of applications, ranging from monitoring environmental conditions  to food −1 [2σ > 600 μW m−1 K−2 [Graphene, the two-dimensional allotrope of carbon, has emerged as an active material in a range of sensor architectures due to its remarkable mechanical durability ,10,11,12−1  and powe m−1 K−2 ,16, rendDespite the favorable characteristics, thermoelectric applications exploiting graphene remain scarcely reported. Previous reports considering the utilization of graphene as an active material for thermoelectric devices include the exploitation of both CVD-grown and solution-processed graphene ,18,19,20The possibility to produce graphene from bulk graphite via a range of liquid-phase methods, e.g., ultrasonic-assisted liquid phase exfoliation (UALPE) ,28, furtWhile different realizations of flexible temperature sensor arrays have been reported previously ,37,38,39The ink approach used to fabricate the graphene film provides a novel and accessible way of preparing flexible and mechanically durable active layers for large-area thermoelectric sensors. Compared to previous temperature-sensing approaches exploiting graphene, the proposed sensor is simple and inexpensive to fabricate, while still comprising multiple pixels, a feature that is lacking in many alternative designs utilizing the thermoelectric effect. The device is demonstrated both as a touch sensor and a real-time thermal distribution sensor, making it suitable for a wide range of applications, for example, in wearable and flexible electronics ,41.The graphene inks were prepared through a process similar to that reported previously . First, 2. The film was then thermally annealed at 375 °C for 30 min to remove the weakly conductive PVP stabilizer from the films, resulting in an order of magnitude increase in electrical conductivity. Following the annealing treatment, 250 nm Al2O3 dielectric and 30/250 nm Ti/Au readout leads were deposited by e-beam evaporation (Edwards E306A) through a shadow mask. External wiring was connected by the use of either silver epoxy  or conductive carbon paste . The produced thermoelectric signals were analyzed with National Instruments SignalExpress software via the NI cDAQ 9213 data acquisition module.The thermal distribution sensor was fabricated as follows: The prepared multilayer graphene ink (45 mL) was spray-deposited onto Kapton polyimide substrate over an area of 6 × 6 cmStructural analysis of the device was carried out using Zeiss Supra 40 scanning electron microscope (SEM), Bruker DekTak XT surface profilometer and WiTec Alpha 300 RA+ Raman spectroscopy equipment. Seebeck coefficients and resistivities of the samples were determined using a Linseis LSR-3 measurement system equipped with a thin film adapter. Five different temperature gradients were used for the measurement and carried out at an average temperature of 34 °C in an inert He atmosphere. The measured temperature difference and voltage values were analyzed using linear regression, and the Seebeck coefficient was obtained from the slope of the fit. Charge carrier mobilities and concentrations of the samples were obtained with Ecopia HMS-5300 Hall measurement system using van der Pauw contact geometry. An infrared camera (Testo 865) was used to acquire reference heat maps for the thermal distribution characterization. The electrical resistance of a sample film was measured under controlled deformation using a Fluke 289 multimeter, as well as under controlled humidity in a closed chamber using a Keithley 2602B source meter.The device architecture was reproduced in finite-element method (FEM) simulation software (COMSOL Multiphysics). The heat directed onto the device surface was modelled as a boundary heat source with a Gaussian spatial temperature distribution. The temperature rise produced by the boundary heat source was limited to 1.2 K, replicating the finite temperature rise resulting from the touch of a finger. Further details concerning simulation parameters and modelling results are included in Figure S5 and Table S1, Supplementary Materials.2O3 dielectric layer separates the remainders of the readout leads from the graphene film. Each readout lead forms an effective thermocouple with the graphene film acting as a common leg. When the contact between a readout lead and the graphene film is heated, a temperature gradient forms between the contact point and the reference ground, resulting in a thermoelectric voltage determined by the effective Seebeck coefficient of the graphene film and the readout lead. As a result, the spatially distributed effective thermocouples act as a sensor array accepting input signals of thermal origin. Since the voltage generation takes place within a single open circuit, the electrical readout wiring of the device is remarkably simplified compared to arrays of individual sensors, requiring only half of the electrical wiring.D/IG ratio of 0.26 before and after the treatment presented in 2D/IG ratio of 0.36 acquired from the post-annealing spectrum [spectrum .2 areas. After annealing, the samples were characterized as summarized in −1 with decreasing film thickness, in sound agreement with the peak voltages obtained in touch sensing experiments. The obtained hole concentration values agreed well with previously reported values for few-layer graphene flakes fabricated via a similar process [−1 K−2 depending on the sample. The results were not largely dependent on film thickness. However, thinner films appeared preferential for sensor application due to both a higher Seebeck coefficient and higher optical transparency, which promotes applications where transparency is important from either a practical or aesthetic standpoint, such as wearable or window applications. Additionally, to observe any possible changes in electrical properties due to deformation of the graphene film, the electrical resistance of a sample film was measured with the film bent to different bending radii, showing only minor changes at the smallest bending radii and thus highlighting the excellent mechanical durability of the films. The relative change in resistance is presented in To investigate the effect of film thickness on the sensor thermoelectric properties, 4, 8, 12 and 16 mL of ink were deposited on 2 × 3 cm process . The decThe transient performance of the device was characterized by carrying out a series of experiments, where the pixels were gently touched by a finger wearing a nitrile glove. Thermal distribution mapping was demonstrated in two separate experiments. First, the device was attached onto the outer surface of a beaker containing warm water at a temperature of 36 °C. The signal was recorded after 15 s, sufficient for the voltage reading to reach a steady state. −1, which corresponded to that of the film of equivalent thickness as presented in Magnitude of the thermoelectric signals in the presented shape detection experiments was typically on the order of 250–370 μV, while thermal noise present in the signals was approximately 8–10 μV. Therefore, the resulting signal-to-noise ratio (SNR) in temperature-based shape detection was roughly 35. SNR was noted to vary depending on the relative temperature between the reference ground and the ceramic piece.2σT κ−1, where κ denotes thermal conductivity, sensing architectures exploiting the thermoelectric effect are poorly compared via these indicators. On the other hand, the thermoelectric sensor performance is largely determined by the Seebeck coefficient, which directs the future search for materials possessing both a high Seebeck coefficient and compatibility with liquid-phase processing.Contrary to the thermoelectric energy harvesting devices conventionally evaluated via power factor or the thermoelectric figure of merit ZT = S−1 [−1 [To assess the performance of the sensor device in comparison with alternative carbon nanomaterials, large-area carbon nanomaterial films with thermoelectric parameters reported are compared to the multilayer graphene films studied in this work. Films made of semiconducting single-walled carbon nanotubes (SWCNTs) have been measured to possess S > 150 μV K−1 . The use−1 ,48. On t−1 [−1 , thus sh2 V−1 s−1 as a function of increasing film thickness [When compared to results from previous studies on p-type liquid-phase exfoliated graphene films, the electronic properties agree well with atmospherically doped films . Howeverhickness , agreeinIn applications of graphene requiring optical transparency, the desired performance is often achieved by reducing the film thickness, resulting in reduced electrical conductance . ConcurrInk formulation similar to the one utilized here has previously been optimized for inkjet printing , paving The demonstrated large-area thermoelectric performance of ink-based graphene films suggests that the concept could be scaled to suit fabrication methods such as gravure and flexographic printing, both of which have already been experimented with 2D material-based inks ,53. In aIn summary, a large-area thermal distribution sensor utilizing a thermoelectric film deposited from low-cost multilayer graphene ink was presented. The inexpensive and facile sensor configuration could detect thermal input from intermittent heat sources, such as human touch, as well as detect objects based on temperature distribution mapping. The finite-element model utilized in studying the device performance provides an accurate reproduction of the concept and allows for optimization of device parameters for the application at hand. The applied fabrication processes are readily scalable into high volumes, which, together with the simple device architecture, offers an accessible route to using multilayer graphene for thermoelectric sensing in application areas such as wearable and flexible electronics.


Findings from molecular studies suggesting that several infectious agents cause sarcoidosis are intriguing yet conflicting and likely biased due to their cross-sectional design. As done in other inflammatory diseases to overcome this issue, prospectively-collected register data could be used, but reverse causation is a threat when the onset of disease is difficult to establish. We investigated the association between infectious diseases and sarcoidosis to understand if they are etiologically related. We conducted a nested case–control study (2009–2013) using incident sarcoidosis cases from the Swedish National Patient Register (n = 4075) and matched general population controls . Infectious disease was defined using inpatient/outpatient visits and/or antimicrobial dispensations starting 3 years before diagnosis/matching. Adjusted odds ratios (aOR) of sarcoidosis were estimated using conditional logistic regression and tested for robustness assuming the presence of reverse causation bias. The aOR of sarcoidosis associated with history of infectious disease was 1.19 . Upper respiratory and ocular infections conferred the highest OR. Findings were similar when we altered the infection definition or varied the infection-sarcoidosis latency period (1–7 years). In bias analyses assuming one in 10 infections occurred because of preclinical sarcoidosis, the observed association was completely attenuated . Our findings, likely induced by reverse causation due to preclinical sarcoidosis, do not support the hypothesis that common symptomatic infectious diseases are etiologically linked to sarcoidosis. Caution for reverse causation bias is required when the real disease onset is unknown.The online version of this article (10.1007/s10654-020-00611-w) contains supplementary material, which is available to authorized users. The etiology of sarcoidosis remains to this day a mystery . The conIn fact, infectious agents gained the most research attention throughout the years largely due to the clinical and histological similarities between sarcoidosis and tuberculosis. Except mycobacteria , 5, the Findings from epidemiological assessments are equally conflicting. Exposure to moldy environments rich in aerosolized infectious agents , and theQuantifying the potential contribution of infectious disease to the etiology of sarcoidosis has profound implications for clinical practice and research, facilitating diagnosis and treatment and guiding future research efforts. To determine whether infectious disease could be etiologically linked to sarcoidosis development, we performed a nested case–control study using information derived from Swedish population-based registers. Our objective was to estimate relative risks of sarcoidosis associated with a history of infectious disease, overall, by sarcoidosis phenotype, type, and temporal proximity of infectious disease to sarcoidosis diagnosis and test the robustness of our findings in the presence of reverse causation bias.We conducted a case–control study nested in the Swedish population (2009–2013). We used the National Patient Register (NPR) to identify individuals with sarcoidosis. The NPR holds high quality data on hospitalizations (nationwide since 1987) and outpatient visits to specialists in public and private practices since 2001. Visits were coded using the International Classification of Diseases (ICD) system . IndividIndividuals with progressive sarcoidosis or debilitating symptoms receive pharmacologic treatment, commonly, systemic corticosteroids, methotrexate, or azathioprine in Sweden , 26. BecUp to 10 controls per case were sampled from the general population at index date from the Total Population Register and matched on birth year, sex, and residential location. Only controls who lived in Sweden at the date their matched case had their second visit for sarcoidosis and had no hematopoietic or lung malignancy within 6 months before or after the index date were included in the analyses.Ethical approval for this study was granted by the Regional Ethics Review Board in Stockholm (Decision No. 2014/230-31).History of infectious disease was defined using information on visits in the NPR listing an ICD code for infectious disease and/or antimicrobial dispensations in the Prescribed Drug Register. Thus, only symptomatic infections listed in Table S1 that led to an interaction with healthcare were captured by this exposure definition. The primary definition was at least one inpatient or outpatient visit listing an ICD code for infectious disease as primary or contributory discharge diagnosis. To approximate infectious disease severity and reduce misclassification, we restricted to hospitalizations, or to visits where infection was the primary discharge diagnosis, or required two or more visits for infection. To capture infections diagnosed and treated solely in primary care, we expanded the primary definition to include at least one dispensation of an antimicrobial medication.Sarcoidosis at a preclinical stage may last for more than 2 years before diagnosis in some cases , 29–31, We obtained demographic information from the Total Population Register including the birth date , sex, birth country , civil status , and county of residence at diagnosis/matching, which we classified into six healthcare regions . From the Longitudinal Integration Database for Health Insurance and Labor Market Studies, we retrieved data on education  and annual gross salary adjusted to 2014 inflation rate  of the yWe hypothesized that a higher genetic susceptibility to or the presence of a comorbid autoimmune disease in sarcoidosis might confound the association between history of infection and sarcoidosis development . To adjuUsing conditional logistic regression models, we estimated odds ratios (OR) for sarcoidosis associated with a history of infectious disease. We reported ORs adjusted for matching factors and ORs further adjusted for deciles of a high-dimensional propensity score estimated separately for each analysis. As detailed in the Supplement, we used a semi-automated algorithm  and dataWe performed several other analyses. First, we calculated the population attributable fraction (as outlined in the Supplement) to assess the contribution of infectious disease to sarcoidosis occurrence. Second, we examined the odds of sarcoidosis conferred by specific types of infection . In addition, we used acne as a proxy of infection by propionibacteria to corroborate reports on their role in sarcoidosis, and urinary tract infections as negative control. Third, we varied the latency period from 0 to 7 years to investigate whether there was effect measure modification by the time since infectious disease diagnosis. Last, to examine if ORs varied by sarcoidosis severity around diagnosis or phenotype, we estimated the association separately for treated and not treated sarcoidosis, and for Löfgren’s and non-Löfgren’s disease, the latter using data from our clinical cohort.Despite the fact that exposure and outcome were collected at least 3 years apart, a critical concern was differential exposure misclassification (reverse causation bias). That is, compared to the mostly healthy controls, individuals who were diagnosed with sarcoidosis were more likely to receive the diagnosis of infection due to undiagnosed preclinical sarcoidosis. Another concern was potential confounding of the association by smoking, data for which we did not have. To check the robustness of the conventional analyses against these two systematic errors, we performed a series of probabilistic bias analysis described in detail in the Supplement. In brief, we estimated bias-corrected ORs from three simulation analyses for differential exposure misclassification and from one simulation for unmeasured confounding. For reverse causation bias, we opted for three bias scenarios to account for the uncertainty around the bias parameters because data on the proportion of cases that had preclinical sarcoidosis were not available .Data were managed and analyzed using SAS software version 9.4  and R version 3.5.3 .We included 4075 newly diagnosed sarcoidosis cases and 40 688 matched general population controls. Cases and controls were on average 51 years old (SD 15.2), 45% were female, and comparable with respect to birth country, civil status, education, and salary  for developing sarcoidosis associated with a history of symptomatic infectious disease resulting in healthcare interaction. This weak association, which did not vary by time between infection and sarcoidosis diagnosis, attenuated completely when tested for reverse causation bias. Most of the observed risk was conferred by infections at sites related to sarcoidosis (e.g. respiratory), but associations with infections at unrelated sites (e.g. urinary tract infections) were also observed. We believe that these contradictory findings are a result of reverse causation bias induced by preclinical sarcoidosis, which may last for years in some cases before symptoms lead to sarcoidosis diagnosis.At first glance, several of our findings  sarcoidosis that spans years before diagnosis. In support of this notion, studies in sarcoidosis have shown that individuals appear to enter a diseased state characterized by sick leave absence, impaired productivity, visits to the doctor, and increased medication dispensing many years before diagnosis is established , 30, 37.In addition to findings from bias analyses, many of the main results support this alternative explanation when more carefully interpreted Table . First, Second, and contrary to previous studies on the role of propionibacteria –9 or mycThird, ORs of sarcoidosis did not vary with time since infection (except when no latency period was used) suggesting that there was no time window during which an infectious agent might have triggered sarcoid inflammation. This finding is in line with our hypothesis that immune disturbance is present for years before sarcoidosis diagnosis. However, we should emphasize that this observation does not preclude the possibility that a pathogen was either dormant or acted more than 7 years before sarcoidosis was diagnosed, or even that infection was simply asymptomatic.Last, assuming that individuals treated for sarcoidosis around diagnosis probably due to sarcoidosis severity are more likely to have a higher burden of immune disturbance compared to individuals with non-severe disease could explain the higher OR of treated sarcoidosis versus a very small increased OR of non-treated sarcoidosis. Based on the distinct genetics , seasonaOur findings should be interpreted in light of the limitations of this study. In contrast to molecular studies, we could not explicitly identify specific pathogens; hence, the effect of one or more infectious agents may have been masked. To mitigate this issue, we used several definitions of infectious disease including healthcare visits and antimicrobial medication dispensations. Moreover, some misclassification of sarcoidosis is expected as we relied on ICD codes and results of histological examinations, bronchoscopies, or imaging were not available. As previously shown , 27, eveDespite the challenges, using prospectively collected population-based data provided us with the necessary power for robust inference, and most importantly, allowed us to address (at least in part) the issue of reverse causation bias and use methods to effectively capture otherwise unmeasured confounding. Finally, we believe that our findings are transportable to populations that are similar in terms of environmental exposures, genetics, and standard of care to the Swedish context.In this large case–control study we observed a weak association between symptomatic infectious disease and the development of sarcoidosis, which is identifiable years before sarcoidosis diagnosis. This association attenuated in bias analyses for reverse causation bias. Overall, we could not find enough evidence implicating common symptomatic infectious diseases in the etiology of the sarcoidosis. On the contrary, we believe that a latent immune disturbance might be the main reason behind the slightly higher burden of infectious disease observed before sarcoidosis diagnosis is established. Despite the challenges, large prospective studies with regular longitudinal examinations are warranted to further investigate this. Additionally, understanding the underlying immunologic mechanisms of this preclinical period is of critical significance to prevent or shorten the time to diagnosis and improve the prognosis of sarcoidosis. Until then, caution for reverse causation bias is required when using register data to define the exposure when the real disease onset is unknown.Supplementary material 1 (DOCX 647 kb)Below is the link to the electronic supplementary material.


Graphene-based hyperbolic metamaterials provide a unique scaffold for designing nanophotonic devices with active functionalities. In this work, we have theoretically demonstrated that the characteristics of a polarization-dependent tunable hyperbolic microcavity in the mid-infrared frequencies could be realized by modulating the thickness of the dielectric layers, and thus breaking periodicity in a graphene-based hyperbolic metamaterial stack. Transmission of the tunable microcavity shows a Fabry–Perot resonant mode with a Q-factor > 20, and a sixfold local enhancement of electric field intensity. It was found that by varying the gating voltage of graphene from 2 to 8 V, the device could be self-regulated with respect to both the intensity (up to 30%) and spectrum (up to 2.1 µm). In addition, the switching of the device was considered over a wide range of incident angles for both the transverse electric and transverse magnetic modes. Finally, numerical analysis indicated that a topological transition between elliptic and type II hyperbolic dispersion could be actively switched. The proposed scheme represents a remarkably versatile platform for the mid-infrared wave manipulation and may find applications in many multi-functional architectures, including ultra-sensitive filters, low-threshold lasers, and photonic chips. Metamaterials can be realized via different architectures having been designed and manipulated to realize exotic effects arising from their structure sequence and configuration. Recently, the attention in metamaterial research has primarily been directed towards tunable and reconfigurable structures that can be used for an active wavefront shaping. This can serve as an effective tool for regulation and switching of electromagnetic waves spreading in multifunctional structured devices10. Active metamaterial functionalities can be obtained using liquid crystals14, superconductors16, nonlinear media18, and carrier injection schemes20. Nonetheless, despite the numerous available methods, studies on active graphene-based metamaterials are of a particular importance22. This is because their properties can be reversibly switched by changing the chemical potential of graphene sheets via electric biasing or optical pumping. Among the different classes of metamaterials, graphene-based hyperbolic metamaterials (GHMMs) have gained considerable attention because of their unique hyperbolic isofrequency, i.e., their permittivity and permeability tensor elements  are of opposite signs, resulting in a strong anisotropy, support for propagating high k-modes, and an enhanced photonic density of states32. Graphene, as a completely two-dimensional (2D) material that only conducts in the plane, shows an anisotropicity that is appropriate for hyperbolic metamaterials (HMMs). Considering an extraordinary wave (TM polarized) in a uniaxial medium, the isofrequency relation can be stated as ω is the wave frequency, and c is the speed of light31. Hence, such a medium has a dielectric response defined by a tensor εx = εy = ε∥ and the out-of-plane component is εz = ε⊥. The spherical isofrequency surface of the vacuum distorts to an ellipsoid for the anisotropic case. However, when extreme anisotropy is present, such that ε∥ ⋅ ε⊥ < 0, the isofrequency surface opens into an open hyperboloid2. Thereby, the same material may affect the incident radiation as a metal or as a dielectric depending on the orientation of the wavevector 33, intensified spontaneous emission34, negative refraction35, strengthened superconductivity36, and increased reflection23. Importantly, HMMs are most commonly created with two-structure classes such as metal-dielectric multilayers29 and metallic nanorod arrays37. In the case of GHMMs, graphene provides conducting electrons making the extreme anisotropicity achievable. As the thinnest material available, graphene also functions as a perfect building slab for multilayer systems, as it enables the minimum possible period and, consequently, the highest possible cutoff for the high k-modes; this has been limited in semiconductor and metal-based HMMs by the high thickness of those materials30. The unusual effects mentioned above have increased a significant amount of theoretical studies focused on the utilization of graphene as an active constituent of HMMs29. Nevertheless, the reported properties relate mainly to the potential of the active switching hyperbolic properties of graphene/dielectric planar heterostructures. Additionally, studies investigating the use of GHMMs as effective photonic devices remain insufficient; therefore, a further progress is necessary.The introduction of artificially engineered composite materials that function as electromagnetic metamaterials has allowed for a novel light-matter interaction at subwavelength scalesεx = εy = ε∥ and the out-of-plane component εz = ε⊥ allowed for determination of the topological transition between elliptic and type II hyperbolic dispersion.In this work, we report a polarization-dependent tunable microcavity based on a GHMM operating in the mid-infrared (mid-IR) frequencies. The operating principle of a tunable device was based on the thickness modulation of the dielectric layers in a GHMM stack. Thereby, breaking the periodicity in a GHMM is manifested in cavity resonant modes. We have modeled a stack consisting of 20-unit cells in which gaps between the graphene sheets are supposed to be filled with a dielectric of varying thickness described by a triangle wave function. It was shown that a subwavelength confinement attributed to volume plasmon polaritons can be optimized and efficiently controlled by acting both on the base dielectric thickness that we modulate and on the gate voltage of graphene. Our calculations proved that the obtained microcavity can be reversibly tuned with respect to both intensity (up to 30%) and spectrum (up to 2.1 µm) by varying the voltage-dependent sheet conductivity of graphene from 2 to 8 V; thus, adjusting the Fermi level via the chemical potential allowing for an ultrafast electrical modulation. Additionally, switching of the device was tested over a wide range of incident angles for both transverse electric and transverse magnetic (TE/TM) modes. Finally, determination of both the in-plane isotropic components ,23. Based on our recent studies, here, we set this value to a constant 23, and the thickness of the graphene monolayer was set to Full-wave numerical simulations of the tunable graphene-based microresonator were performed using Lumerical FDTD Solutions software which employs an algorithm based on the conformal finite-difference time-domain method. The modeled HMM geometry shown in Fig. 31:The effective medium permittivities for an anisotropic multilayer composite were computed using the effective medium theory (EMT). The method follows a generalized Maxwell–Garnett approach to obtain analytical expressions for the effective permittivity in parallel (||) and perpendicular (⊥) directions defined below for the multilayer metamaterial38:40. Without taking into account the external magnetic field, the isotropic surface conductivity intra and the inter-band term inter:5. The chemical potential (22:6 m/s), 16 m−2 V−1 is an empirical constant, and 21. In the sub-wavelength limit, the graphene-dielectric layered architecture can be examined as a homogeneous effective medium with the anisotropic permittivity tensor 32.If we assume that the electronic band structure of a graphene sheet cannot be affected by the neighboring graphene sheets, the effective permittivity of graphene mentclass2pt{minim2 averaged material data. To design the GHMM-based microcavity, the thickness of the dielectric layers in the HMM stack was modulated. The modulation was based on a half period triangle wave function, and the base dielectric thickness in the first unit cell was set as In the proposed model, the dielectric permittivity was set to a constant It should be noted that the dielectric thickness increased until reaching a maximum value in the middle of the stack and, then, it decreased to reach the initial value again in the last unit cell.−7. The described methodology allowed us to adapt the GHMM to design a tunable hyperbolic microcavity in the mid-IR frequencies.In our analysis we used periodic boundary conditions (PBC) for normal incidence, and broadband fixed angle source technique (BFAST) boundary conditions for obtaining the angular characteristics. In addition, to ensure both stability of the algorithm and high accuracy of calculations, we used uniform spatial grid with 100 nm step and additional mesh override regions around graphene layers with 1 nm step and 10 nm buffer; the auto shutoff threshold was set as 10z direction, as depicted by white arrows. In Fig. 23. In addition, the wavelength at which this transition occurs can be self-regulated via a voltage-controlled chemical potential. Then, using the procedure described above, we modulated the dielectric thickness in the HMM stack with a triangle wave function for In order to demonstrate that modulation of the dielectric thickness in the GHMM stack results in a microcavity, we designed two stacks, i.e., a stack with an unmodulated (constant) dielectric thickness and a modulated one. Then, the spatial distribution of their electric field intensities was studied, as shown in Fig. entclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minima41 and by Avrutsky et al.42. Graphene-based hyperbolic microcavity supports plasmonic modes which are commonly denominated gap plasmon polaritons (GPPs) and are strongly confined inside the stack43. Noteworthy is the fact that when the number of adjacent nanocavities (intended as the number of dielectric slabs loaded between two graphene sheets) increases, a collective repulsion of these modal indices appears. This interplay between these cavity plasmon modes stimulates their hybridization44, thus giving rise to extremely confined volume modes called volume plasmon polaritons (VPPs)45. Indeed, when the parameters of a subwavelength graphene-based multilayer composite are modulated (or superstructured) on a larger, wavelength scale, the propagation of VPPs in the resulting multiscale hyperbolic metamaterials is accompanied by photonic-band-gap phenomena. In our case, modulation of the dielectric thickness with a triangle wave function enabled us to achieve a great degree of control over such plasmons in the entire volume of the stack. It should be noted that when the stack geometry is periodic , stop bands due to Bragg reflection form within the volume a plasmonic band47. Contrarily, when cavity layers are sandwiched in an otherwise periodic stack, resonance peak of the Fabry–Perot (FP) nature arises within the stop band. Specifically, mid-IR waves reflecting from a partially reflecting graphene separated by a distance described by the triangle wave function can interfere constructively and form a resonating FP mode. At this point, it is worth noting that instead of mirrors (used in most classic resonance cavities) as a separate section, interface of dielectric/magnetic materials can act as a reflecting surface depending on the strength of dielectric permittivity (εr) and magnetic permeability (μr), and it can support FP modes in varieties of dielectric resonators48. A rectangular bar of silicon nanowire and dielectric nano ribbons are selected examples for supporting this statement50.An extensive explanation of the light propagation inside anisotropic multilayer composites has been given by Meierg = 2 V and Vg = 8 V, the transition from elliptic to type II hyperbolic dispersion can be tuned effectively up to ~ 1.9 μm for unmodulated and up to ~ 2.2 μm for modulated GHMM. Furthermore, by modifying the base dielectric thickness ε⊥) is constant while only the parallel permittivity component (ε∥) changes with wavelength. Interestingly, the change in the gate voltage of graphene does not affect the perpendicular permittivity of the HMM and, therefore, the dashed lines in Fig. In order to determine the maximum tunability of both unmodulated and modulated GHMM, based on the method described above, we determined real part of the permittivity tensor components as a function of a wavelength for two extreme voltages , as depicted in Fig. 52. Therefore, the presented concept based on GHMMs seems to be particularly promising. Additionally, unlike classic resonant microcavities, the Q-factor increases with increasing electrical stimuli, and thus the efficiency of the device also increases. It is crucial in state-of-the-art technologies, as it gives the possibility of increasing the Q-factor and tunability at the same time.The above-mentioned properties of the hyperbolic microcavity, i.e., enhancement of the electric field intensity, shift of the FP resonance spectral position, and microcavity Q-factor can be expressed as a function of both, the base dielectric thickness In the last step, we studied the angular reflection characteristics, as well as the spectral position of the dip (corresponding to the FP peak in transmission) for both the TE and TM modes for the hyperbolic microcavity, as shown in Fig. 52. The practical implementation of our scheme allowed a blue/red shift of the transition wavelength by adjusting the base dielectric thickness or controlling the Fermi level of graphene. The latter is especially effective if accomplished via electrical tuning54. Hence, shifting the transition wavelength further into the IR can be carried out by adopting the lower chemical potential of graphene or a thicker dielectric. Taking into account the angular reflection spectra, this class of microcavities was sensitive to the incident light angle/polarization, which is crucial in applications such as angular-selective and polarization-dependent plasmonic architectures. It is worth noting that in multi-layer graphene structures is interlayer charge screening effect55. However, it can be seen that the carrier density share of the 3rd layer is already quite low, and that of any layer above the 3rd layer is negligibly small55. We believe that the concept outlined here provides a novel and promising platform for a variety of applications that depend on a mid-IR energy enhancement and precise spectral switching of the electromagnetic resonances.In this work, a novel technique to design a tunable hyperbolic microcavity utilizing GHMMs was proposed and theoretically demonstrated. Further, we demonstrated a scheme for modulating the dielectric thickness in the HMM stack via the use of a triangle wave function. Therefore, the proposed plasmonic architecture allowed us to fully use the structural properties of graphene-based multilayered HMMs as a fundamental element of the active hyperbolic microcavities. The results clearly show that the resonance of the metadevice could be continuously and reversibly switched both with respect to its intensity (up to 30%) and wavelength (up to 2.1 µm) in a controllable manner. Furthermore, our calculations indicated that the graphene-dielectric multilayer structure displays an optical topological transition from an elliptical to a type II hyperbolic dispersion in the mid-IR range, confirming the theoretical predictions from previous works


Evidence is sparse and inconsistent on the role of a dual marker strategy (DMS) combining Copeptin with cardiac troponin T (cTnT) for instant rule-out of a non-ST-segment myocardial infarction (NSTEMI) when high sensitivity cardiac troponin T (hs-cTnT) is used.Data on 10,329 patients from 5 trials were pooled to evaluate initial Copeptin in combination with hs-cTnT against a single marker strategy (SMS) based on hs-cTnT < limit of detection. Endpoints were sensitivities and negative predictive values (NPV) for rule-out of NSTEMI, 30-day all-cause mortality and rates of applicability for DMS or SMS.p = 1.0], but applicability was 2.4-fold higher  with DMS than SMS. In a secondary analysis on DMS after inclusion of high risk patients, performance and applicability were similar.NPV for rule-out of NSTEMI was high, exceeding 99.0% for the lower limits of the 95% confidence intervals (99.0% vs 99.2%) for DMS and SMS, and NPV for all cause death at 30 days was similar with very low mortality after rule-out [0.07% (0.0–0.4%) vs 0.0% (0.0–1.2%), Findings corroborate the 2015 European Society of Cardiology recommendation to use dual marker strategy for instant rule-out of NSTEMI, extending evidence to hs-cTnT. Novel data demonstrate a comparably safe and effective instant rule-out with Copeptin in combination with hs-cTnT versus a single marker strategy based on very low hs-cTnT but a more than twofold higher applicability of the dual marker strategy without the need to exclude very early presenters or other important subgroups.Dual marker strategy using hs-cTnT at 99th percentile and Copeptin versus ESC 0-h immediate rule-out based on hs-cTnT < limit of detection The use of high-sensitivity cardiac troponin (hs-cTn) assays has enabled acceleration of the diagnostic process of acute myocardial infarction (MI) in patients presenting with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS). The various options recommended by current ESC guidelines  include Both strategies have shortcomings that have to be balanced against their advantages. In particular, the single hs-cTn-based strategy (SMS) requires an appropriate interval of 2–3 h between onset of symptoms and blood sampling to avoid under-diagnosis of MI due to the “troponin blind interval”. In addition, the single low hs-cTn strategy can only be applied for a small proportion 10–25%) of eligible candidates for rule-out .The most striking difference was the 2.3-fold higher applicability of DMS versus the single hs-cTnT strategy  and sensitivities [96.2% (95%CI 93.8–97.7) vs 99.6% (95% CI 97.8–99.9)] to rule out an NSTEMI, and a consistently higher applicability [58.7% (95% CI 57.1–60.2) vs 27.9% (95% CI 26.2–29.7)] of DMS versus SMS.Likewise, negative predictive values of DMS vs SMS were similar for prediction of death at 30 days [99% (95% CI 99.6–99.9) vs 100% (95% CI 98.8–100)].Thus, the diagnostic and prognostic performance of DMS remained high despite inclusion of high-risk patients, while rates of suitable candidates for the algorithm (applicability) slightly declined as only a fraction of the patients at high risk are anticipated to present with normal values of hs-cTnT and Copeptin. As shown in Fig. These data extend available information on the usefulness of DMS combined with hs-cTn, particularly for the Roche 5th gen. hs-cTnT assay at the 99th percentile cutoff. In addition, accumulating evidence from the Biomarker-in-Cardiology 8 (BIC-8) trial, a large randomized intervention trial  backed bA potential disadvantage, that hitherto has limited the faster adoption of DMS, is the need to run a non-fully automated analyzer , 3. Neve


Over the past decades, graphene has attracted much attention from the scientific community due to its broad applications in the optoelectronics industries We fabricated a vertical photovoltaic type G/PbS/Ti device by making use of the Ti/PbS Schottky junction and discussed the photocurrent transient characteristics. Lead sulfide (PbS) was deposited directly on large area CVD  graphene by CBD . Temperature dependent photocurrent spectra of our G/PbS/Ti photovoltaic devices were measured by a Fourier transformed infrared (FTIR) set-up.In this paper, we present the experimental procedures and the raw experimental data for the direct chemical deposition of PbS on CVD-graphene for high performance photovoltaic infrared photo-detectors. The manuscript is already available  Specifications Table•Graphene tends to peel off from glass substrates when immersed in solutions containing chemicals such as NaOH. These data are important as we describe direct deposition of PbS on graphene from a solution containing 570 mM of NaOH. The deposition was successful after the annealing of graphene/glass.•Scientific researchers who want to chemically synthesize materials directly on graphene can benefit from our data.•These data can be helpful for further studies using graphene and PbS for flexible infrared devices taking advantage of the high transmission of graphene in the infrared spectral range.•We provide detailed experimental processes for direct chemical synthesis of PbS on graphene.•Photocurrent transient behaviours have been attributed to the accumulation of photo-generated carriers at interfaces and back injection of the carriers. These explanations can be extended to the photocurrent transient behaviours of other heterostructures.1This work presents a step-by-step procedure and the raw experimental data for direct deposition of PbS on large area CVD-graphene for high performance photovoltaic infrared photo-detectors. This article provides all the raw data in reference In this paper, we show a schematic diagram for the deposition of PbS films in supplementary figure S1(a). Mobility data for PbS/graphene/glass are given in S1(b). The observed high mobility values of the films on graphene indicate that majority carriers (holes) of PbS films flow through graphene.23)2, 99.3%; Kanto Chemical Co., Ltd., Japan), for Pb source, 90 mM thiourea (CS(NH2)2, 98%; Kanto Chemical Co., Ltd., Japan) for S source and 570 mM sodium hydroxide  as complexing agent. Using a Teflon beaker containing 100 ml deionized water, NaOH bids were first put in, shortly after which Pb (NO3)2 was added to the solution and stirred using a magnetic stirrer for 10 min. CS(NH2)2 was added to the solution and finally the substrates were immersed vertically in the solution. The deposition was done at room temperature conditions and stirred at 180 RPM. The deposition time was 1–2 h PbS films were produced by chemical bath deposition (CBD) method using 180 mM lead nitrate  under 560 mTorr for about half an hour, followed by rapidly cooling the film to room temperature (10°C min−1) under flowing H2 under 90 mTorr. The graphene/Cu film was coated with a thin layer of poly methyl methacrylate (PMMA). The Cu foil under the graphene was etched away in an aqueous solution containing 0.1M ammonium persulfate. After washing with deionized water several times, the PMMA/graphene was transferred onto a microscope slide glass substrate A single layer of graphene was grown on a copper foil using CVD method. First, the Cu foil  was loaded into a quartz tube of the CVD system and annealed at 1000°C under 90 mTorr with flowing 10 sccm of HWe successively deposited 1–5 layers of graphene on the microscope slide glass by the PMMA assisted layer-by-layer transfer process. To improve adhesion between graphene films and glass substrates, the substrates were thermally annealed to remove all residual PMMA. We learned that post-annealing was important for the adhesion of PbS films on graphene/glass. Graphene/glass were annealed at 600 °C for 2 h. An e-beam evaporator with a metal mask was used to deposit Ti electrodes on PbS/graphene/glass.The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article.


In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The higher Pb(II) ions removal was achieved with the 0.3 molar proportion of xNH2/DMS-1 reaching 99.44% efficiency. This result suggests that the functionalized material can be used as an efficient adsorbent for Pb(II) ions from aqueous solution.Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different  Lead is a heavy metal that has produced considerable interest due to the health risks it causes, even at low concentrations ,2. Due t2/g) and has a spherical pore shape with a wormhole morphology [2 groups to promote an accurate mass transfer in the pore network of NH2/DMS-1. There are several techniques to remove lead ions from drinking water and wastewater, the most common being filtration, ion exchange and reverse osmosis ,17. Howerphology ,32. In prphology , like NHThe influence of the sorbent morphology on its sorption capacity is well known. For example, it was found that the initial adsorption rate onto platelet mesoporous adsorbents was rapid and faster than the rates of rod-like and fiber-like morphologies . However2⋯Pb(II) structures [The adsorption of Pb(II) cations by mesoporous silica functionalized with amino groups has been investigated previously ,38,39,40ructures ,36.xNH2/DMS-1 exhibits an open pore structure and accessible adsorption sites, there are necessary conditions for a good contact between the lead ions and the adsorption sites. In addition, to evaluate the Pb2+ adsorption in the functionalized DMS-1, structural characterization by Fourier Transform Infrared Spectroscopy (FTIR) spectra, N2 adsorption-desorption isotherms, X-Ray Diffraction (XRD), Thermogravimetric Analysis-Derivative Thermogravimetry (TGA-DTG), and X-Ray Photoelectron Spectroscopy (XPS) were performed. It has been demonstrated that the main advantage of the DMS-1 sorbent was the stability of their -Si–O–Si– bonds formed between the amino and the hydroxyl groups on silica surface. Although it is commonly believed that the more amino groups bonded to the silica surface the better cations removal from an aqueous solution, the results presented in this work shows that ammonia content should be optimized to obtain the maxima of lead removal. It was concluded that the amino-functionalized DMS-1 adsorbents should be interesting and promising sorbents for heavy metal ions removal from aqueous solutions.Within this scenario, the aim of this study was to develop an effective adsorbing system made of DMS-1 functionalized with amino groups to remove Pb(II) ions from aqueous solutions. To attain this, the following conditions were optimized to perform the adsorption: concentration of amino group, contact time, initial pH, and temperature, regarding the effectiveness for the Pb(II) removal. Taking into account that the 106–PO70–EO106, 99%, Aldrich) was used as the surfactant and tetraethyl orthosilicate  as the silica source. In a typical synthesis procedure, the triblock copolymer was dissolved in a mixture of deionized water and 2M hydrochloric acid  solution, and the mix was stirred for 1 hour, after that time, the required quantity of TEOS was added to the mixture at 30 °C and it was kept under magnetic stirring for 24 h. The mixture was subsequently transferred to polypropylene bottles and they were heated at 80 °C for 48 h. Then, the obtained solid was filtered, washed with deionized water, dried at 110 °C for 18 hours and finally, it was calcined in an air atmosphere at 550 °C for 4 h to remove the organic molecules [Disordered Mesoporous Silica 1 (DMS-1) was synthesized according to the sol-gel method proposed by Zhao (1998) and Fuertes (2004) ,42. The olecules .2(CH2)3Si(OEt)3, 99%, Aldrich) in ethanol  [2-modified samples were labeled hereafter as 0.2 NH2/DMS-1, 0.3 NH2/DMS-1, and 0.4 NH2/DMS-1. One gram of DMS-1 was dispersed into a solution made of APTES-ethanol for 30 min at 30 °C. After that time, deionized water was gradually added and lastly, the liquid suspension was put to stirr for additional 30 min at 30 °C. Water was incorporated in order to perform hydrolysis of the alkoxide groups of APTES. The added water amount was twice the amount required to completely hydrolyze the APTES content. Finally, the solids obtained were dried at room temperature and posteriorly at 50 °C for 24 h.The functionalization of the internal surface of mesopores in DMS-1 has been achieved by the ex-situ method. The amino groups were attached to the internal mesoporosity in DMS-1 using a solution of 3-Aminopropyl-triethoxysilane (APTES NHAldrich) . The matThe efficiency of the amine-functionalized DMS-1 materials to remove Pb(II) ions from water was determined by a batch technique. To evaluate this removal efficiency, 20 mL of 100 mg/L Pb(II) aqueous solutions were put in contact with 0.1 g of the adsorbent material. The Pb(II) solution was prepared with a Pb standard .The effects of contact time, pH , the temLead (II) ions concentration was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), in water samples taken before and after adsorption experiments. The effects of the parameters listed above on the adsorption capacity for functionalized DMS-1 and bare DMS-1 were evaluated. Determination of Pb(II) ions concentration was performed in an Optima 8300 spectrometer . The emission lines were used according to the standard Environmental Protection Agency (EPA) method to analyze this metal . Adsorbe−4 mbar) to ensure a clean, dry surface free of any loosely adsorbed species. The specific areas (SBET) of the samples were calculated via the standard Brunauer–Emmett–Teller (BET) procedure [0 < 0.3. The total pore volume (Vp) was estimated from the amount of nitrogen adsorbed at a 0.99 relative pressure [The mesoporous materials were studied to know their textural properties by the nitrogen adsorption isotherms registered at 77 K using a volumetric Autosorb-IQ2 adsorption analyzer  . Before rocedure  using thpressure ,49,50. Tpressure . The thepressure ,53 using−1. Pore arrangement on DMS-1 was analyzed by low-angle X-Ray Diffraction (XRD). XRD diffractograms were obtained with a Rigaku Ultima IV diffractometer  using Cu Kα (λ = 1. 5406 Å) radiation [−8 mbar. The binding energy was determined using the carbon C(1s) line as a reference with a binding energy of 284 eV [The functional groups on the amine-functionalized adsorbents were studied by an Infrared Spectrum Two spectrophotometer  ,55,56,57adiation  in the 2adiation ,60. X-Raf 284 eV . The staf 284 eV .2/DMS-1 are shown in 0 is a H1 type, distinctive from materials with pore diameters between 6 and 8 nm, and is typical for wormhole structured DMS-type materials [2/DMS-1 showed a decrease in the desorption first stage, suggesting that the NH2 groups are attached to the internal surface of the DMS-1 pores. Textural properties were obtained from the nitrogen adsorption-desorption isotherms. Specific surface area, total pore volume, and average pore size were determined for all samples. Nitrogen adsorption-desorption isotherms for the bare DMS-1 and 0.3NHaterials . The iso2/DMS-1 samples showed a uniform and narrow pore size distribution, which had average size values of about 6.5 and 5.6 nm, respectively. This result corroborates that the modification reaction of DMS-1 using a molar concentration of 0.3 of APTES did not produce significant damage to the structure of the material. Therefore, the surface area and the total pore volume of the modified material reduced their values significantly compared to those determined for the pure DMS-1. The decrease in the pore volume value in the 0.3NH2/DMS-1 is a consequence of the functionalization process. The nitrogen adsorption–desorption study also confirms that the analyzed samples are DMS-type materials.Texture properties from the materials are summarized in 2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 materials. For the DMS-1 sample, two Bragg reflections were observed at the values of 0.02° and 0.34°, which indicate there are two different pore sizes repeated in the mesh structure, corresponding to pores formed among particles (0.02°), and the textural pores; both in the mesopore range. The functionalized materials 0.2NH2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 showed similar Bragg reflections at 0.02° and about 0.34°. However, the reflections about 0.34° suffered a slight displacement toward smaller angle values, their intensity and width increased as a function of the amino group concentration. For 0.4NH2/DMS-1 adsorbent, this reflection was shorter and thinner than that corresponding to 0.3NH2/DMS-1; these differences could be produced by saturation of functionalizing molecules in the open side of pores, complicating the diffusion of these molecules within the pore.2/DMS-1 material are shown in SEM images of the 0.3NH−1 are clearly visible, which are related to the asymmetric and symmetric stretching vibrations of Si–O–Si bonds, respectively [−1 band could be associated with stretches of Si-O- or Si-OH groups, probably hydrogen-bonded to adsorbed H2O molecules. The band at 1631 cm−1 is correlated to the O–H deformation bending vibration of physically absorbed water. The broad band centered at 3400 cm−1 is due to silanol groups having cross hydrogen bonding which interacts with the adsorbed water molecules [−1) of methylene groups [−1 in the range of 2700–3400 cm−1 is attributed to NH2 stretching vibration. Noticeably, the 0.3NH2/DMS-1 exhibits higher intensity of this band than 0.4NH2/DMS-1 counterpart suggesting the largest surface exposure of NH2- groups. The weak N–H bending vibration at 950 cm−1 and the symmetric –NH2 bending vibration around 1561 cm−1, confirms the incorporation of amino groups [The FTIR spectra of pure DMS-1 and the adsorbent materials with different amino concentration are displayed in ectively ,68,69,70olecules ,72. It ie groups ,74. In to groups .2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 mesoporous materials are shown in 2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 samples exhibit weight losses of 19.93%, 21.04% and 21.04% respectively. The profiles  with 99.44% removal. Thus, although it is commonly believed that the more amino group bonded to the silica surface the better cations removal from an aqueous solution, the results presented in this work shows that amount of amino groups should be optimized to obtain the maxima of lead removal.In order to establish the appropriate adsorption conditions for Pb(II) removal with amine-functionalized materials, several tests were made at natural pH and 30 °C for 1 h. The adsorption of Pb(II) ions for each adsorbent 0.2NH2/DMS-1) was studied by a batch operation, the experiments were performed to determine the effects of contact time, the pH value, adsorption temperature and initial lead ion concentration in solution. The effect of contact time on the removal efficiency of Pb(II) within the range from 0 to 60 min under pH 5 at 25, 30 and 35 °C is observed in The adsorption of Pb(II) ions by the selected adsorbent  but more PbOH+ species are present in the solution [2 occur and precipitate in solution with pH > 6 [2/DMS-1 for Pb (II) adsorption was improved with an increase of the pH of solution from 2 to 5. Taking in mind that the surface of bare silica is acidic due to presence of silanol groups (its isoelectric point (IEP) is close to pH 2) whereas the surface of the silica grafted with aminopropyl groups is more basic [2+ cations on the negatively charged surface of adsorbate increases above the PZC point of this adsorbate. Thus, the possible explanation of an increase of Pb(II) removal with an increase of pH of solution are two: (i) the amount of protonated amino groups decreased (–NH2 groups) due to their de-protonation forming negatively charged sites, and/or (ii) the higher electrostatic attraction at pH of 5. At higher pH, the surface of 0.3 NH2/DMS-1 has a negative charge because of the high concentrations of –OH ions in the aqueous solution, favorable for the adsorption of Pb(II). Considering the study by Huang et al. [2+ and Pb(OH)+ species are dominant species at pH < 6 and pH > 7.5, respectively. The hydrolysis of Pb2+ to form Pb(OH)+ and Pb(OH)2 occurs at pH 3.7 and 6.8, respectively. Therefore, the best removal of lead by 0.3NH2/DMS-1 was performed at pH = 5.The influence of the pH on the adsorption capacity was studied and the results are exposed in solution . The speh pH > 6 ,80, whicre basic , the depg et al. , the Pb2xNH2/DMS-1 can be explained considering the attachment of ligands as the point-wise linkage to the silica surface, while at higher molar proportion of amino groups (xNH2/DMS-1) the amino groups are attached as the loop structures bonded with the silica, as shown as shown in The optimization of the DMS-1 surface archived with the 0.3 molar proportion of 2/DMS-1 under pH 5 for 60 min, the removal efficiency increased gradually with the rise of temperature from 25 to 30 °C, but decreased from 99.57% to 98.63% with the intensification in the temperature from 30 to 35 °C. This decrease suggests that the adsorption process is exothermic. The study reveals that the adsorption process of heavy metal ions was improved at 30 °C possibly by the exothermic electrostatic interactions [ractions .2/DMS-1 adsorbent was investigated. The effect of initial metal concentration on the adsorption rate was analyzed within the range 10–500 mg/L at pH 5 and 30 °C for 60 min, as shown in 2/DMS-1 could be effectively realized using acid treatment, as it was demonstrated for ZnCl2-MCM-41 sorbent regenerated with HNO3 [In order to explain the mechanism responsible for Pb(II) removal from aqueous solutions by adsorption on functionalized siliceous DMS-1 materials, the effect of the initial concentration of Pb(II) ion adsorption on the most optimized 0.3 NHith HNO3 . Similarith HNO3 .2/DMS-1 adsorbent was examined by the XPS wide-scan spectrum in 2/DMS-1 sample before and after lead ion adsorption from the solution containing 100 ppm of Pb(II) ions. The binding energies of Si2p, C1s, O1s, N1s, and Pb4f7/2 core electrons and surface atomic ratios (N/Si and Pb/N) are compiled in 2 and protonated -NH3+ bonds respectively. These species were detected before Pb(II) adsorption and also after adsorption, although the –NH2 gets protonated, there are still enough concentration of -NH2 able to coordinate with the Pb2+ ions over the pair of free electrons. The atoms of nitrogen located in the surface of the silicon resulted in an atomic ratio of 0.13, and the Pb/N revealed an atomic ratio of 1.38.The most effective adsorbent was studied by XPS techniques to elucidate the nature of adsorption sites. The introduction of the Pb(II) ions onto 0.3NH2/DMS-1 showed two peaks (Pb4f7/2 and Pb4f5/2) resultant from a spin-orbit doublet. Identifying the Pb4f7/2 core level, the binding energy at 138.17 eV was observed and it is higher than those reported for the orthorhombic PbO compound (137.2 eV) and more similar to the binding energy reported for Pb(NO3)2 (138.6 eV) [7/2 during adsorption. 38.6 eV) ,91,92. T2/DMS-1 systems with groups amino to remove Pb(II) ions from aqueous solutions were studied. The affinity between the synthesized materials and the heavy metal is attributed to their atomic properties and to the pH value from the solution. The optimum pH values for the removal of the lead ions by 0.3NH2/DMS–1 material were pH 4 to 6. Lead adsorption on amino-modified DMS-1 materials may be explained by the Van der Walls electrostatic interactions between the Pb(II) ions and the -NH2 surface.NH


Graphite nanoplatelets (GNPs), a functional 2D nanofiller for polymer nanocomposites, utilize natural graphite as a raw material due to its stacked graphene layers and outstanding material properties upon successful exfoliation into nano-thick sheets. However, the increasing demand for natural graphite in many industrial applications necessitates the use of graphite from waste resources. We synthesized GNPs from waste chicken feathers (WCFs) by graphitizing carbonized chicken feathers and exfoliating the graphitic carbon by high-speed homogenization and sonication. We then separated GNP from non-exfoliated carbon by centrifugation. This paper describes the morphology, chemical, and crystalline properties of WCF and its carbon derivatives, as well as the structural features of WCF-derived carbons. We obtained GNPs that have a 2D structure with huge variations in particle size and thickness. The GNP shows the presence of carbonyl groups, which are mostly attached at the edges of the stacked graphene sheets. Defects in the GNP are higher than in graphene synthesized from direct exfoliation of natural graphite but lower than in graphene oxide and reduced graphene oxide. To produce GNP of high quality from WCF, restacking of graphene sheets and concentration of carbonyls must be minimized. With their commercial availability, low cost, and structure similarity to graphene, graphite nanoplatelets (GNPs) continue to be a significant component of modern polymer nanocomposites ,3,4,5,6.GNPs have been prepared previously, using different methods ,8, but t6 t annually [6 t of WCFs every year [To contribute to this effort, we have prepared GNPs from carbonized and graphitized waste chicken feathers (WCFs). Recently, carbon-based nanomaterials have been produced from WCFs ,35 and, annually . Worldwiery year . While tery year . The masery year . Howeverery year ,46. This3·6H2O  were used in the graphitization of CCF. Moreover, 2-propanol  and deionized water were utilized as a solvent during high-speed homogenization of GCF. WCFs were obtained from a poultry processing plant in Bulacan, Philippines. Hydrochloric acid  and FeClWCFs were washed several times with water mixed with liquid detergent, to remove blood, manure, and other unwanted components. The washed WCFs were laid out on galvanized iron sheets and sun-dried for 3 days. WCFs were further conditioned in a laboratory oven  at 105 °C for 24 h before being cut into ~10 mm long pieces. After manually separating the rachis, the barbs were cut into ~2 mm long fibers and milled in an analytical mill  for 10 min. The resulting WCF powder was sieved (mesh 100) before carbonization.3·6H2O  were added to distilled water (100 mL g−1 CCF). The pH of the solution was adjusted ~2 by adding HCl. The mixture was heated at 60 °C for 5 h, using a hot plate , while being continuously homogenized at 1000 rpm by a high-speed homogenizer  equipped with a dispersing element . GCF was separated from the homogenized solution by vacuum filtration and dried in a laboratory oven at 105 °C for at least 48 h before further use.The carbonization and graphitization of WCF were performed by following the method of Akhavan et al. . Briefly−1, as measured by drop-casting and drying until constant weight. The yield of GNP from GCF was 4.8 wt%.To prepare GNP, 10 g GCF was added to 1000 mL of 40 wt% 2-propanol aqueous solution and was subjected to high-speed homogenization at 5000 rpm for 90 min. The homogenized solution was probe sonicated  under an ice bath at amplitude 80 for 90 min. GNP was separated from non-exfoliated GCF by centrifugation  at 500 rpm for 120 min. The upper 30 mL of the centrifuged mixture was pipetted to several watch glasses and dried in a hot plate at 100 °C, to recover the brown GNP powder. The concentration of GNP in the pipetted solution was estimated to be 0.6 mg mLμm scan size. Analysis of line profiles was performed by using XEI software . The particle size distribution of GNPs was determined by using ImageJ software . The morphologies of WCF, CCF, and GCF were examined by using a scanning electron microscope  operated at 2 kV. The samples were mounted on a carbon tape placed on an aluminum stub. A small amount of GCF was diluted in ethanol, drop-casted, and dried in a sample stub before viewing in a field emission transmission electron microscope  operated at 200 kV. GNP solution was drop-casted and dried in a clean glass slide before examining in an atomic force microscope  at non-contact mode. Two-dimensional images were generated at 10 × 10 −1 and resolution of 4 cm−1. The background spectrum was obtained without the sample prior to the actual measurements.The chemical structures were studied, using a Fourier transform infrared spectrometer  coupled with a diamond/ZnSe attenuated total reflectance (ATR) crystal plate accessory. Four scans were accumulated for each measured spectrum, with a range of 650–4000 cmα radiation (λ = 0.154 nm) at 30 kV and 10 mA. Diffraction patterns were recorded from 2θ = 5°–80°, with an increment of 0.04°. Moreover, d-spacing and stacking height (cL) of graphitic carbon detected in GNP and GCF were determined by using Bragg and Scherrer equations [θ = 10–40°, using GRAMS/AI software. Impurities in CCF were determined by X-ray fluorescence  operated at 25–50 kV and 200 μA for an analysis area of 1 mm.The crystallinity of the samples was analyzed by X-ray diffraction , using Cu-Kquations . The Bra−1 and analyzed by using GRAMS/AI. After manual baseline correction, curve-fitting was performed by using the Levenberg–Marquardt algorithm. The spectra were deconvoluted, using Gaussian functions, and best-fitted with 5 bands.Raman spectra of carbon samples were taken on a micro-Raman spectrometer  with a 50 mW, 532 nm diode laser for excitation. Raman spectra were recorded from 800 to 2000 cmThe morphology of WCF a shows a3·6H2O g−1 CCF and 0.0001–0.001 mol Fe(NO3)3·9H2O g−1 sawdust in [High-speed homogenization applied during graphitization of CCF to produce GCF decreased the particle size a. Moreovwdust in , and theThe liquid-phase exfoliation of GCF to yield GNP resulted in 2D nanomaterials of varied particle sizes and thicknesses . Most of−1) [−1) and Amide II (1533 cm−1) [−1), which was eliminated after its exfoliation and drying to produce GNP.The chemical structure of GNP  indicate−1) ,55. The −1) . The car−1) ,57. Carb33 cm−1)  in the kθ = 25°) in their crystalline structures , resulting from the mild evaporation of intercalated H2O molecules during thermal annealing of GNP at 100 °C [Lc than GCF  as a result of restacked graphene sheets due to thermal annealing [Both GNP and GCF show a graphite-like arrangement , and CaCO3  [2 and Na2CO3 in detergent [α-helix (10.2°) and β-sheet (20.7°) crystal structures of peptide chains in WCF [CCF also shows graphitic ordering, as observed previously for pyrolyzed feathers . Other dd 32.6°) ,64. Resuetergent  have rems in WCF .−1) for the in-plane bond stretching motion of sp2 carbon; the D1 band (1339 cm−1) for the in-plane breathing vibration of sp2 carbon within structural defects; the D3 band (1433 cm−1) for the amorphous sp2 carbon; and the D4 band (1224 cm−1) for the sp2-sp3 bonds or C-C and C=C stretching vibration in polyenes [−1) denotes an artifact of the instrumental setup and is not related to the carbon samples [I/ITotal). In all the samples, the G and D1 bands have the largest band areas as compared to the other bands. The FWHMs of G (154.0–167.7 cm−1) and D1 (128–140.4 cm−1) bands are larger than in natural and synthetic graphites  but comparable to graphene oxide  and thermally reduced graphene oxide  [θ = 11° for graphene oxide  . This cone oxide , the carIG/ITotal > ID1/ITotal). GNP has the lowest ID1/IG ratio, i.e., GCF (0.75) > CCF (0.71) > GNP (0.56), meaning that it has the lowest number of defects [ID1/ITotal. The defect content of GNP is higher than most graphene reported in the literature, e.g., ID1/IG < 0.18 [ID1/IG > 1 [ID1/IG of GCF, as well as the narrower FWHM of the G band and higher IG/ITotal, compared to CCF, can be attributed to the defects brought by the growth of graphitic tubules on the surface of CCF.All carbon samples show a well-ordered graphitic structure  carbonize WCF to produce CCF; (2) graphitize CCF at low temperature and acidic conditions, using an iron catalyst to generate GCF; (3) homogenize and sonicate GCF, to exfoliate the graphitic carbon; and (4) separate the exfoliated graphite from non-exfoliated carbon by centrifugation to yield GNP. The obtained GNPs are 2D nanomaterials of varied particle size and thickness. The GNP has carbonyl groups attached at the edges of the stacked graphene sheets. Defects in GNP are higher than in graphene prepared from direct exfoliation of natural graphite but lower than in graphene oxide and reduced graphene oxide. To consider WCF as a sustainable source of graphite for high-quality GNP, further research is needed to lessen restacking of graphene sheets, lower the concentration of carbonyl groups, and reduce the defects in the GNP.