The analysis of the content of the different functional groups also suggested that the reduction rate of the oxygenic functional group was C–O > C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>O > O–CO. The supercapacitive performance of rGO showed that the oxygenic functional groups contributed to some pseudocapacitance and resulted in a larger specific capacitance. At the same time, however, it is also accompanied by poorer rate performance and durability, which will be improved by removing the oxygenic functional groups by extending the reduction time. With an optimized reaction condition of a reduction time of 24 h, the obtained rGO exhibited excellent stability in floating tests at 3.0 V and 45 °C for 60 days. These findings pave the way for the development of high quality graphene materials for cost-effective and practical graphene supercapacitors.To investigate the relationship between the oxygen-containing functional groups of graphene and the stability of supercapacitors, reduced graphene oxide (rGO) containing different oxygenic functional groups was prepared by varying the reduction time of GO using hydrazine as the reducing agent. TEM, XRD, Raman, and XPS characterizations revealed that, as the reduction time increased, the sp This study aims to investigate the relationship between the residual functional groups on graphene sheets and the stability of graphene supercapacitors, thereby improving the performance of graphene supercapacitors. Among the various energy storage devices, supercapacitors (SCs) have attracted tremendous attention due to their rapid charging and discharging, high power density, and outstanding cycling stability.12–18 As for the electrodes, carbon materials have been one of the most widely studied and used materials in supercapacitors due to their abundant sources, low cost, good chemical stability, easy processing, and high specific surface area. Graphene, a two-dimensional carbon nanomaterial with a large specific surface area, high electrical conductivity, high mechanical strength, and good chemical stability, is considered as a most promising electrode material for supercapacitors.19–21 Various methods have been reported to synthesize graphene, including mechanical exfoliation, liquid-phase exfoliation, chemical vapor deposition, epitaxial growth, electrochemical deposition, microwave processing, and chemical reduction of graphene oxide (GO). Chemical reduction is the most widely used method due to its simplicity, low cost, and easy processability for high production.19,20,22–32 However, there are still some issues in the application of graphene materials for supercapacitors.With the rapid development of industrial applications, the vast consumption of oil has resulted in major environmental issues, such as greenhouse gas emissions, and has necessitated the development of alternative energy sources.33,34 Although the stability of supercapacitors is a key factor for their practical applications, to the best of our knowledge, there were very few studies on the relationship between the reduction process of GO and the stability of graphene supercapacitors. The residual functional groups on the graphene sheet after chemical reduction will usually lead to degradation of the electrolyte. There are several oxygen-containing functional groups attached to the graphitic carbon plane in the structure of GO, including epoxide, hydroxyl, carbonyl, and carboxyl, making GO a hydrophilic substance.35,36 Furthermore, when GO is reduced to graphene, many of the hydrophilic groups on GO are removed, making the obtained graphene become hydrophobic, and this process will in turn hinder the re-stacking of graphene layers.The current research on the application of graphene in supercapacitors mainly focuses on the preparation of graphene material with large capacitance by tuning the synthetic parameters.To address the abovementioned issues, this study aims to optimize the structure of the residual functional groups on graphene sheets by tuning the reduction parameters, thereby understanding the relationship between the residual functional groups and the stability of graphene supercapacitors, and improving the performance of graphene supercapacitors.2.2.1.34,37,38 GO was first obtained from graphite by a modified Hummers' method.39 5 g of natural graphite (Alfa), 3.75 g of NaNO3, and 310.5 g of H2SO4 were placed in a beaker and stirred for 30 min in an ice bath at 0 °C. Under vigorous agitation, 22.5 g of KMnO4 was then added slowly to the above solution and the temperature was kept at below 10 °C. The resultant mixture was then stirred for 2 days at room temperature, after which 1 L of H2SO4 aqueous solution (5%) was added drop by drop over a period of 1 h. After stirring for 2 h, 150 g of H2O2  was added to the mixture, making the color of the suspension change from brown to yellow. The GO suspension was allowed to settle down overnight and was then diluted by using 0.1 mol L−1 HCl, centrifuged 5 times, diluted with deionized water, and continuously centrifuged (30 000 rpm) until the pH value of the supernatant reached 7 to remove impurities.Graphene was synthesized by chemical reduction of graphene oxide (GO) using hydrazine as the reducing agent.40–42 The chemical reactions of GO, with the concentration fixed at 2.0 g L−1, were carried out for different reduction times  to explore the effect of reduction time on the structure and properties of the graphene synthesized. The concentration of hydrazine was 10 mL/1 g GO. The samples obtained with different reduction times were denoted as rGO-t-1, rGO-t-2, rGO-t-3, rGO-t-6, rGO-t-12, rGO-t-24, and rGO-t-48, respectively.The obtained GO solution was reduced to graphene by hydrazine using chemical reduction with different concentrations of GO for different reduction times, rinsed with ethanol, and finally dried in a vacuum at 60 °C.2.2.λ = 1.5418 Å) and Raman spectroscopy . The functional groups on GO and graphene were characterized with X-ray photoelectron spectroscopy  and Fourier transform infrared spectroscopy . Elemental analyses were performed with energy-dispersive X-ray spectroscopy . Nitrogen adsorption–desorption data (Quantachrome Autosorb iQ) were collected to calculate the specific surface area by the Brunauer–Emmett–Teller (BET) method and the distribution of pore sizes was obtained using density functional theory (DFT) calculations.Morphology of the synthesized graphene was characterized by both scanning electron microscopy  and transmission electron microscopy . Atomic force microscopy (AFM) samples were prepared by spin-coating the rGO dispersion on a Si wafer. AFM measurements were conducted with a scanning probe microscope  using the tapping mode. The structure was also examined by using powder X-ray diffraction  was employed as the electrolyte in the coin cell. The mass of each electrode was about 3 mg. To avoid the influence of moisture in air, all operations were carried out in a glove box filled with Ar.To evaluate the electrochemical performance of the synthesized graphene films, coin cells were assembled using a graphene film with a diameter of 15 mm as the electrodes, a layer of glass-fibre membrane as the separator, and two pieces of aluminium foil as the current collectors. 1-Ethyl-3-methylimidazolium tetrafluoroborate  were obtained at current densities varying from 0.1 to 20 A g−1. The CV and GCC tests of supercapacitors in EMI-BF4 were performed in the range from 0 to 3.7 V. Electrochemical impedance spectroscopy (EIS) measurement was also performed over the frequency range from 10 kHz to 0.1 Hz. The coin cell was subjected to a floating test (voltage holding) at a voltage of 3.0 V and temperature of 45 °C in an oven. The specific capacitance was calculated from the GCC curves ranging from 0 to 3.7 V at a constant current density of 0.2 A g−1 after 1 day, 3 days, 5 days, 10 days, 15 days, 20 days, 30 days, 40 days, 50 days, and 60 days of floating. The cyclic performance measurements were conducted at a charge–discharge current density of 1 A g−1 using a Land battery test system.All electrochemical tests were carried out in a two-electrode system using an electrochemical workstation (Biologic VSP-300). Cyclic voltammetry (CV) measurements were conducted at different voltage scan rates ranging from 10 mV s16,43C is the specific capacitance of the supercapacitor, m is the mass of two electrodes, I/m is the applied current density, t is the discharging time, and U is the potential window.Based on the results of the GCC measurements, the specific capacitance was calculated in accordance with the discharging time at each current density by using the following equation:3.3.1.44 The effective removal of oxygenic functional groups would restore the six-fold symmetry of graphene. When the reduction time is below 12 h, the diffraction rings corresponding to the (100) and (110) planes of graphene are blurred and broad, suggesting a heavy presence of residual oxygenic functional groups. When the reduction time is more than 12 h, the diffraction rings corresponding to the (100) and (110) planes of graphene can be observed clearly, indicating the effective removal of oxygenic functional groups. Moreover, the diffraction spots became bright and sharp from graphene after reduction for 24 h, which indicated a sufficient removal of oxygenic functional groups and the restoration of the sp2 bonding of graphitic carbon.The morphology of rGO synthesized with various reduction times was studied by transmission electron microscopy (TEM). via van der Waals interactions, which is difficult to redisperse even with extended sonication. The re-stacking of graphene will lead to a decrease in the specific surface area of materials. High-resolution TEM (HRTEM) images of folded graphene edges were further used to reveal the number of stacked layers of graphene as illustrated in 2 g−1 (rGO-t-1), 487 m2 g−1 (rGO-t-3), 491 m2 g−1 (rGO-t-6), 481 m2 g−1 (rGO-t-12), 440 m2 g−1 (rGO-t-24), and 404 m2 g−1 (rGO-t-48), corresponding to reduction time of 1 h, 3 h, 6 h, 12 h, 24 h, and 48 h, respectively, as illustrated in 45,46To characterize the specific surface area of the rGO synthesized with different reduction times, nitrogen adsorption/desorption isotherms were obtained, and the results are displayed in θ = 11.0° (corresponding to a d-spacing of 0.80 nm). Compared with the typical (002) diffraction peak of graphite  as shown in Fig. S3,d-spacing of GO is due to the oxygenic functional groups  in the basal plane of GO. After 1 h reduction by hydrazine, the sharp diffraction peak of GO at 2θ = 11.1° disappeared, and a new broad diffraction peak of rGO appeared at 2θ = 22.6° (corresponding to a d-spacing of 0.39 nm). With the increase of reaction time, the diffraction peak of the obtained rGO shifted to a higher angle and stayed almost constant  after the reaction time reached 12 h. This result suggests that these oxygenic functional groups had an important effect on the interlayer spacing of rGO. With the reduction of GO, most of the oxygenic functional groups were removed, and the interlayer spacing of the resulting rGO gradually decreased. In addition, the removal of functional groups also led to the re-stacking of graphene sheets due to van der Waals forces to create a thicker layer, which is consistent with the features observed in the TEM images.47To further characterize the evolution of the microstructure of GO during reduction, the XRD patterns of rGOs synthesized with various reduction times were collected and analysed. As shown in −1 represents the in-plane stretching vibrations of the sp2 bonded carbon, and the D peak at ∼1350 cm−1 represents the defective and disordered structures in the hexagonal lattice of graphene. The intensity ratio of the D peak and G peak (ID/IG) is often useful to evaluate the degree of defective structure of carbon materials. −l, while the G peak of rGO moved to 1575 cm−1, which is attributed to a graphitic “self-healing” with the removal of oxygenic functional groups and restoration of the hexagonal structure of graphene.48 The ID/IG ratio for GO is 0.98 and it increased to 1.14 for rGO-t-1, indicating the introduction of more lattice defects accompanied by removal of the oxygenic functional groups in the reduction process. This is because, although the reduction process restores the conjugated sp2 carbon structures, the accompanying removal of carbon atoms bonded to the oxygenic functional groups would leave some vacancies and the defects would eventually lead to an increase in the ID/IG value. As shown in ID/IG increased from 1.14 to 1.34 when the reduction time increased from 1 h to 24 h and remained almost unchanged with further prolongation of the reduction time to 48 h, indicating that the degree of reduction reached its limitation.Raman spectroscopy is a widely used technique to characterize the structural characteristics and properties of graphene materials. The G peak at ∼1580 cm49 These results suggest that the oxygenic functional groups were effectively removed from the carbon planes during the reduction process. Furthermore, an EDS elemental analysis of the obtained rGO was also carried out , sp3-hybridized carbon (C–C), hydroxyl and epoxy groups (C–O), carbonyl groups (CO), and carboxyl groups (O–CO), respectively.33,46 To monitor the evolution of individual functional groups during the reduction process, the contents of each functional group were estimated by the percentage of its area relative to the whole area of the C 1s peak. C bonding and C–C bonding increased correspondingly. The relative proportion of the CC bonds increased from 46.92% (for GO) to 66.09% (for rGO-t-24), and the relative proportion of the C–C bonds increased from 7.84% (for GO) to 27.25% (for rGO-t-24), while the relative proportion of the C–O group decreased significantly from 30.84% (for GO) to 1.30% (for rGO-t-24), which implies that GO was reduced to graphene effectively by hydrazine.To obtain a quantitative picture of the evolution of the oxygenic functional groups during the reduction process, the C 1s XPS spectra of GO and rGOs were deconvoluted into five peaks at binding energies of 284.5 eV, 285.5 eV, 286.5 eV, 287.9 eV, and 289.1 eV, corresponding to the spO), and carboxyl groups (O–CO) during the reduction process. As shown in 2 graphitic structures. From the changing trend of each oxygenic functional group with the reduction time, each type of functional group changed significantly in the first 5 h. After that, the trend of change slowed down and it remained almost unchanged after 12 h, implying that the chemical reduction mainly occurred in the initial stage. And regarding the reduction rate of the various functional groups, the hydroxyl and epoxy groups (C–O) are the fastest ones, followed by the carbonyl groups (CO), and the slowest ones were the carboxyl groups (O–CO). It was also found that the contents of C–O, CO, and O–CO groups in GO were 30.8%, 9.8%, and 4.6%, respectively, but after 48 h reduction, these three types of functional groups in rGO-t-48 were decreased to 1.0%, 2.4%, and 2.4%, respectively. It means that 96.8% C–O, 75.5% CO, and 47.8% O–CO functional groups were removed after 48 h reduction, indicating that the CO and O–CO groups were more stable and less likely to react with hydrazine. The C–O groups are expected to react first in the presence of hydrazine since they are single bonded groups with a bonding energy of 358 kJ mol−1,50 while the CO groups are double bonded functional groups with a higher bonding energy of 745 kJ mol−1 and need more energy to break them apart.503.2.4, an ionic liquid with a large electrochemical window up to 3.7 V, as the electrolyte. −1. As shown in As mentioned in Introduction, the aim of this work was to study the relationship between the structure of rGO and its supercapacitor performance and stability. To examine the supercapacitor performance and stability of the rGOs synthesized with various reduction times, symmetric two-electrode cells were assembled using EMI-BF−1 have triangular shapes. Consistent with the results obtained in the CV curves, the charge–discharge curve of rGO-t-1 exhibited a slight deviation from the linear slope of an ideal triangular shape, indicating a pseudocapacitive behaviour due to the presence of a large number of oxygen-containing functional groups with a C/O ratio of 6.3. With an increase in the reduction time, the charge–discharge curves of the obtained rGO returned to the ideal isosceles triangular shape, suggesting an excellent capacitive behaviour with further removal of the oxygenic functional groups. The specific capacitance calculated from the charge–discharge curves of rGO with different reduction times is plotted in −1 (rGO-t-1) to 157 F g−1 (rGO-t-6) when the reduction time was increased from 1 h to 6 h, due to the disappearance of the contributions of pseudocapacitance accompanied by the removal of oxygenic functional groups. Moreover, as the reduction time was further increased to 48 h, the capacitance of rGO was maintained at about 150 F g−1 without any obvious decrease. When the current density was increased from 0.2 to 20 A g−1, the specific capacitance of rGO-t-1 exhibited a large decrease, and the capacitance retention was only 69% as shown in As shown in Rs) of rGO is 6.9 Ω, 5.9 Ω, 4.8 Ω, 4.5 Ω, 4.3 Ω and 4.3 Ω for rGO-t-1, rGO-t-3, rGO-t-6, rGO-t-12, rGO-t-24, and rGO-t-48, respectively, indicating an increase of the conductivity of the rGO film with the increase of reduction time. The semicircle in the high frequency region represents a charge transfer resistance (Rct) and the diameter of the semicircle is related to the diffusion of charge carriers at the electrode/electrolyte interface. The continuous decrease in the diameter of the semicircle from rGO-t-1 to rGO-t-48 reveals the decrease of Rct with increasing reduction time of rGO. These results indicate that rGO obtained with a longer reduction time, accompanied by the removal of more oxygenic functional groups and restoration of the conjugated sp2 carbon structures as discussed above, on the one hand, facilitated electrolyte ions to be reversibly physiosorbed/desorbed on the surface of graphene, while on the other hand, improved the conductivity of rGO and allowed fast electron transfers. All these factors contributed significantly to the excellent rate performance of the graphene electrode obtained with a longer reduction time. Furthermore, the straight line in the low frequency region can explain the capacitive characteristics of the electrode material. The relatively smaller slopes in rGO-t-1 and rGO-t-3 indicate a deviation from the ideal capacitive behaviour, while the slopes for rGO with increasing reduction time approached being vertical, suggesting a return to the ideal capacitive behaviour. These features are in agreement with their CV and charge–discharge curves.The rate performance was also verified by the EIS measurements. −1 were also carried out at room temperature. As shown in Fig. S5,To characterize the stability of the graphene electrode, supercapacitor cells were tested by a very hard constant-voltage holding method with an applied voltage of 3.0 V at an atmospheric temperature of 45 °C for a period of 1500 h. As shown in 4.O > O–CO. The performance of the graphene supercapacitor is largely determined by the carboxyl functional groups that remained on the basal planes of graphene. In the process of GO reduction, the reducing agent needs a longer time to reach these oxygenic functional groups to react with them. Combining the functional groups, the structure of graphene, and the results of durability tests, it indicates that the deterioration of graphene supercapacitors is a result of the redox reactions of the acidic carboxyl functional groups on the graphene sheets. It has guiding significance for the production of high-performance graphene for supercapacitor applications.In this study, we optimized the structure of residual functional groups on graphene sheets in the preparation of GO and established an effective process by tuning the operation parameters to reduce GO. With a comprehensive consideration of the synthesis parameters for graphene production and the performance of supercapacitors, we have developed a mechanism accounting for the structural and electrochemical properties. With an increase in reduction time, more oxygenic functional groups were removed. The reduction rate follows C–O > CShiqi Lin: conceptualization, investigation, formal analysis, visualization, writing – original draft. Jie Tang: conceptualization, formal analysis, writing – review and editing, supervision, project administration, funding acquisition. Kun Zhang: visualization, validation, writing – review and editing. Youhu Chen: visualization. Runsheng Gao: visualization. Hang Yin: visualization. Lu-Chang Qin: formal analysis, visualization, writing – review and editing.There are no conflicts of interest to declare.NA-005-D2NA00506A-s001


This work focuses on the assessment of UT1-UTC estimates from various types of sessions during the CONT17 campaign. We chose the CONT17 campaign as it provides 15 days of continuous, high-quality VLBI data from two legacy networks (S/X band), i.e., Legacy-1 (IVS) and Legacy-2 (VLBA) (having different network geometry and are non-overlapping), two types of Intensive sessions, i.e., IVS and Russian Intensives, and five days of new-generation, broadband VGOS sessions. This work also investigates different approaches to optimally compare dUT1 from Intensives with respect to the 24 h sessions given the different parameterization adopted for analyzing Intensives and different session lengths. One approach includes the estimation of dUT1 from pseudo Intensives, which are created from the 24 h sessions having their epochs synchronized with respect to the Intensive sessions. Besides, we assessed the quality of the dUT1 estimated from VGOS sessions at daily and sub-daily resolution. The study suggests that a different approach should be adopted when comparing the dUT1 from the Intensives, i.e., comparison of dUT1 value at the mean epoch of an Intensive session. The initial results regarding the VGOS sessions show that the dUT1 estimated from VGOS shows good agreement with the legacy network despite featuring fewer observations and stations. In the case of sub-daily dUT1 from VGOS sessions, we found that estimating dUT1 with 6 h resolution is superior to other sub-daily resolutions. Moreover, we introduced a new concept of sub-daily dUT1-tie to improve the estimation of dUT1 from the Intensive sessions. We observed an improvement of up to 20% with respect to the dUT1 from the 24 h sessions. Very long baseline interferometry (VLBI) is a microwave-based space geodetic technique that measures the difference in arrival time of signals from extra-galactic radio sources  received simultaneously at two or more radio telescopes . VLBI is  . In this  :(1)θ(Tu)https://ivscc.gsfc.nasa.gov/index.html, accessed on 1 March 2022). The sole objective of Intensive sessions is to determine UT1-UTC in a timely manner, and they consist mainly of one VLBI baseline. Such sessions typically last for approximately one hour. The baselines are typically chosen, providing a long east–west extension, as dUT1 is highly sensitive to it )In this work, we estimated the dUT1 from the individual and combined legacy networks. We kept the temporal resolution to be daily and hourly. In addition, we estimated dUT1 from the different Intensive sessions. We employed different comparison strategies in our study, which will be detailed in In The CONT17 campaign officially started on 28 November 2017 at 00:00:00 UTC, and it ended on 12 December 2017 at 23:59:59 UTC . The parWe assigned Legacy-1 as “L1”, Legacy-2 as “L2”, and combined legacy network as “L12”, for convenience. We will use these short names throughout the rest of the article. The number of observations and scans contained in legacy and VGOS networks and different Intensive sessions are illustrated in The results discussed in this study are derived from VLBI analysis, the details of which will be specified in this chapter. In this work, we used the GFZ version of the Vienna VLBI Software , VieVs@Gftp://cddis.gsfc.nasa.gov/pub/products/iers/finals2000A.all, accessed on 1 March 2022) and not the posterior values. The dUT1 were estimated as continuous piecewise linear functions (PWLF) in the VieVS@GFZ. For further understanding, we computed the root mean square (RMS) and uncertainty of the formal error values from the Equations   and Intequations  and (4),Equation ).(5)r=∑The dUT1 estimation from the 24 h sessions follows a two-step procedure: single-session analysis and global solution analysis. In the first step, we analyze various parameters as shown in In contrast, we do not estimate parameters such as polar motion, CPO, station and source coordinates, and tropospheric gradients when analyzing Intensive sessions because these sessions do not contain enough observations see . Besideshttps://cddis.nasa.gov/archive/reports/formats/ngs_card.format, accessed on 1 March 2022) that we created from the associated vgosDB. A VGOS session during the CONT17 campaign spans from 23:00 to 23:00 UTC (next day). We synchronized the start and the end epoch of a VGOS NGS file with respect to a 24 h legacy session, i.e., from midnight to midnight (next day). We removed the first hour of observations, i.e., 23:00 to 00:00 UTC. Then, the observations during 23:00 to 00:00 UTC were added from the next session and so on. However, for the last VGOS session, the last hour of the day remains empty as there is no next session present from which we could add the observations. This is performed to achieve a fair comparison between dUT1 from VGOS and from legacy networks. We follow a similar two-step procedure . This approach is based on the estimates of dUT1 from 24 h legacy and Intensive sessions with hourly resolution. Then, we compare the estimated values for the same epoch. For example, if the Intensive session spans from 18:30 to 19:30 UTC, we obtain dUT1 estimates for 18:00, 19:00, and 20:00 integer hour UTC epochs. The determination of three-hourly unconstrained estimates from Intensive sessions is ambitious; however, we would like to try it in this study. Next, we compare it with hourly dUT1 from the legacy network at its mean epoch, i.e., 19:00 UTC. This procedure is applied for both Intensive networks. In this approach, the hourly dUT1 value from the legacy networks, for example, at 19:00 UTC, may be influenced by the neighboring dUT1 values at 18:00 UTC and 20:00 UTC as they are parameterized using piecewise linear offsets in VieVs@GFZ. Therefore, to mitigate this effect, we created pseudo Intensive sessions, which will be discussed in detail in the next paragraph.In the third approach, we compared dUT1 from Intensive sessions with the artificially created “pseudo Intensive sessions”. We extracted 1 h of observations from the 24 h legacy networks. The start and end epoch of these pseudo Intensive sessions are synchronized with respect to the epoch of the actual Intensive sessions. We analyzed these pseudo Intensive sessions as the standard Intensive sessions see . TherefoFor better understanding, we calculated and compared the RMS differences between dUT1 estimated from the Intensive and 24 h (legacy networks) sessions from the three approaches as discussed above. Using the second and the third approach, we can expect to observe the influence of the piecewise linear parameterization.In this section, we introduce a novel approach to improve the dUT1 values estimated from the Intensive sessions. As sub-daily variations are present in dUT1 from Intensive sessions, we aim to minimize these effects. These so-called ties, i.e., correction values (CV), are computed from the 24 h sessions at hourly resolution.j indicates which datasets were used, i.e., 24 h sessions, Desai HFEOP, or Gipson HFEOP, t denotes the mean epoch of an Intensive session, and i is the number of days (there are 15 days of sessions in the CONT17 campaign). In the case of Intensive sessions, we take weighted mean, i.e., the mean epoch is assigned twice the weight than the preceding and succeeding epoch. For comparison, we computed a reference value, which is the root mean square of the difference between dUT1 from the 24 h session for daily resolution and Intensive session.The computation of CV is the difference between the mean values of hourly dUT1 over a day and weighted mean value of dUT1 at the Intensive epochs from 24 h sessions or HFEOP models (Gipson  and DesaWe observed that the dUT1 (daily resolution) from the L2 network have lower uncertainty as compared to the L1 network see . This coThe dUT1 (hourly resolution) contains sub-daily variations, which can be seen in We also computed dUT1 for various sub-daily resolutions to determine the optimal length for sub-daily dUT1. Considering L1 and L12 solution, 6 h resolution shows highest improvement of around 7% and 2.5% in dUT1 with respect to 1 h dUT1 RMS values, respectively see . HoweverIn this study, dUT1 are estimated from two different Intensive networks: IVS-Int and Ru1-Int. We can observe that dUT1 estimated from Ru1-Int have higher RMS and formal errors as compared to IVS-Int see . One of The dUT1 values estimated from the Intensive sessions along with three legacy solutions are plotted in The second approach was used to compare the hourly dUT1 estimated from the Intensive sessions and 24 h sessions at the mean epoch of an Intensive session. The statistical assessment in In the third approach, we computed the RMS of the differences between dUT1 from the IVS-Int with respect to the pseudo Intensive sessions. We compared these values with the RMS values, which we computed from the first and the second approach and plotted them in We computed new dUT1 values after applying the CV to the dUT1 from Intensives. We estimated the RMS of the differences between the reference value and the three cases. In We estimated dUT1 for daily resolution from the VGOS network and assessed its performance against dUT1 from the three legacy solutions plus the combined solutions and Intensive sessions. We can see from In addition, we compared sub-daily dUT1 from VGOS and legacy VLBI. For the hourly resolution of dUT1, we found high formal errors and almost no correlation with respect to the legacy networks. This could be due to the parameterization with linear spline segments (PWLF) for the hourly resolution. In addition, we observed from We assessed the dUT1 from the CONT17 from various 24 h sessions, such as legacy and VGOS networks, and one-hour Intensive sessions, such as IVS and Quasar VLBI Network (Russian) Intensive networks. The results in this article are an extension and continuation of the previous results contained in . MeanwhiDaily-resolved dUT1 from legacy networks shows strong correlation of 0.86. Thus, the dUT1 obtained from the legacy networks is comparable even though the networks have different geometry, stations, scans, and observations. We also evaluated the dUT1 from the legacy networks with hourly resolution. The correlation coefficient between individual legacy networks is 0.62, which is smaller than the correlation of the daily dUT1 values. The possible reason could be due to the involvement of smaller numbers of observations. We observe an increase in the formal errors, and this could be due to the smaller number of observations per parameter, and fewer participating stations. In addition, we assessed dUT1 for various sub-daily resolutions and found that the 6 h resolution performs better than the rest.Apart from that, we assessed the dUT1 from the two Intensive networks, i.e., IVS (Kokee Park and Wettzell) and Quasar VLBI Network (Badary and Zelenchukskaya) Intensive sessions. The dUT1 estimated from Russian Intensive sessions shows higher RMS and formal errors compared to IVS Intensive sessions. This could be due to the shorter baseline length of Badary and Zelenchukskaya (4364 km) compared to Kokee Park and Wettzell . The dUT1 is sensitive to the baselines with longer east–west extension, and the Kokee Park–Wettzell baseline is about 2.5 times longer than the Badary–Zelenchukskaya.We further analyzed the three different approaches to compare the dUT1 from the Intensive sessions with the legacy networks. We created pseudo Intensive sessions from the 24 h Legacy-1 and Legacy-2 networks, where start and end epochs were synchronized with the actual IVS and Russian Intensive sessions. For the case of pseudo Intensive sessions synchronized with respect to IVS Intensives, we found an improvement in the agreement of 20.5% and 37.5% for dUT1 from IVS Intensive sessions with respect to the L1 and L2, respectively. We observed a higher amount of agreement compared to the second approach. This is primarily due to the synchronized epoch of the pseudo Intensive sessions. This reveals the shortcomings of parameterization using piecewise linear functions, especially when estimating for sub-daily dUT1.This work includes the novel idea of implementing sub-daily dUT1-tie to improve the dUT1 from Intensive sessions. The concept involves a CV, which is computed using dUT1 from 24 h sessions (L1 and L2) for hourly resolution. The implementation of the CV derived from Gipson HFEOP sessions improves the highest agreement between dUT1 from IVS-Intensives and L1 sessions by 20% more than the case without CV. In the case of L2 sessions, the improvement in agreement is approximately 12%. The dUT1-tie does seem to improve the estimation of dUT1 from Intensive sessions during the CONT17 period. The time scale for such analysis should be extended to a longer period and is intended for future work.VGOS sessions took place during the CONT17 period for five days. We assessed the quality of dUT1 from VGOS sessions with respect to the legacy network for these five days. The dUT1 from the VGOS show a high correlation of 0.86, 0.82, and 0.95 with respect to L1, L2, and L12 solutions for daily resolution, respectively. The formal errors of the estimated dUT1 from VGOS are comparable with the L1 solution. The results from the VGOS show strong agreement with the legacy networks despite having fewer observations and only five stations. Therefore, we can say that the VGOS compares well with standard VLBI, even when examining five days of observations only. Hence, it might be challenging to assess the long-term agreement with the legacy networks. In addition, these five sessions are a prototype of limited VGOS with only five stations (the sixth station did not record useful observations), no high-gain schedule , and the stations are located in the northern hemisphere only. All this cannot be generalized to judge “real VGOS”. As the VGOS sessions are not explicitly designed for estimating sub-daily dUT1, we computed sub-daily dUT1 from the VGOS for different temporal resolutions. The 6-hourly estimated dUT1 performs better than other resolutions and shows a strong correlation of 0.78, 0.89, and 0.85 with dUT1 from the L1, L2 and L12 6-hourly solutions, respectively.


Background: Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease whose etiology remains unknown. This study aims to explore diagnostic biomarkers and pathways involved in IPF using bioinformatics analysis.Methods: IPF-related gene expression datasets were retrieved and downloaded from the NCBI Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened, and weighted correlation network analysis (WGCNA) was performed to identify key module and genes. Functional enrichment analysis was performed on genes in the clinically significant module. Then least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE) algorithms were run to screen candidate biomarkers. The expression and diagnostic value of the biomarkers in IPF were further validated in external test datasets (GSE110147).Results: 292 samples and 1,163 DEGs were screened to construct WGCNA. In WGCNA, the blue module was identified as the key module, and 59 genes in this module correlated highly with IPF. Functional enrichment analysis of blue module genes revealed the importance of extracellular matrix-associated pathways in IPF. IL13RA2, CDH3, and COMP were identified as diagnostic markers of IPF via LASSO and SVM-RFE. These genes showed good diagnostic value for IPF and were significantly upregulated in IPF.Conclusion: This study indicates that IL13RA2, CDH3, and COMP could serve as diagnostic signature for IPF and might offer new insights in the underlying diagnosis of IPF. Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease of unknown cause . The gloMajor advances recognizing biological mechanisms and biomarkers have occurred over the past decade with the development of transcriptome analysis . NumerouIn this study, we used multiple bioinformatics methods to identify key gene co-expression modules, functional pathways, and significant diagnostic biomarkers in IPF, and constructed a potential diagnostic signature for IPF.https://www.ncbi.nlm.nih.gov/geo/). The included datasets met several selection criteria: 1) the datasets published in the past 15 years; 2) samples had been extracted from lung tissue; 3) the total sample size in two groups was at least 30; and 4) raw data were available in the datasets. Five datasets that met the selection criteria and the diagnostic criteria for IPF were analyzed in this study  based on the following criteria: the soft-thresholding power β was set as 20, the minimum number of genes in the modules was 30, and the threshold for cut height to merge possible similar modules was 0.25. To further analyze the module, we calculated the module eigengene, which represents the expression of all genes in a given module. The correlation between the module eigengene and the genes was defined as the module membership, and the correlation between the genes and clinical traits was defined as the gene significance. Model eigengene values were correlated with control and IPF groups by Pearson’s correlation. Finally, the module most highly associated with IPF groups was selected for further analysis.We used DEGs to construct a gene co-expression network  package . We consp < 0.05 was set as the cutoff to identify significantly enriched pathways.For further understanding the function of the genes in the most related module for IPF, we conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses using Clusterprofiler R package . The ontTo screen candidate diagnostic biomarkers, we identified genes with high within-module connectivity of the modules (|module membership| > 0.8) and |gene significance| > 0.6 as hub genes and used them to build the least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) algorithms . The LASvia ROC analysis.The area under the curve and the receiver operating characteristic (ROC) curve were plotted with the pROC package to evaluate the capability of candidate diagnostic biomarkers between controls and IPF. We randomly divided samples from the training dataset into a training set and a test set (7:3) using the createDataPartition function in the caret R package and constructed the diagnostic model using the logistic regression algorithm in the training set. We used the test set and validation datasets to evaluate the capability of the diagnostic model between IPF and controls The training dataset sample distributions before and after the removal of batch effects were visualized in a two-dimensional PCA cluster diagram , and theβ = 20  was selected as the correlation coefficient threshold to identify the module-trait relationship  of IL13RA2, CDH3, and COMP was greater than 0.9 in training and validation datasets (GSE110147) . When thNumerous studies have found that dysregulated genes are involved in the progression of IPF and might be potential diagnostic biomarkers of IPF . HoweverThe mouse bleomycin-induced fibrosis model is generally viewed as the standard in modeling pulmonary fibrosis . Recent CDH3, also known as placental cadherin, is a classic cell-to-cell adhesion molecule that regulates multiple cellular homeostatic processes in normal tissue . High CDCOMP is an ECM glycoprotein that plays a role in fibrillogenesis and collagen secretion . DysreguIPF is a chronic, progressive lung disease characterized by the progressive deposition of ECM proteins. Available evidence suggests that the ECM plays a central role in the pathogenesis of IPF . WGCNA iAlthough the three-gene signature constructed here appears to be a potential diagnostic signature for IPF, this study has some limitations. First, the expression and exact mechanisms of the biomarkers should be further investigated experimentally. Second, the diagnostic value of the three-gene signature was only tested in microarray datasets in this study and should be further validated with clinical data. Third, other genes in the clinically significant module were not studied in this study.In conclusion, we revealed the involvement of the key gene co-expression module and functional pathways in the pathogenesis of IPF. In addition, we identified IL13RA2, CDH3, and COMP as potential biomarkers of IPF and constructed an integrated three-gene signature of IPF. This work provides further insights into the underlying molecular mechanisms and diagnosis of IPF.


Electron microscopy investigation reveals that the obtained hybrid electrodes consist of numerous nanosheets of MoS2 and graphene which are randomly distributed. The MoS2/graphene hybrid anodes exhibit excellent cycling stability with high reversible capacities (442 mA h g−1 for MoS2/graphene (40 h); 553 mA h g−1 for MoS2/graphene (20 h); 342 mA h g−1 for MoS2/graphene (10 h)) at a high current rate of 250 mA g−1 after 100 cycles, whereas the pristine MoS2 electrode shows huge capacity fading with a retention of 37 mA h g−1 at 250 mA g−1 current after 100 cycles. The incorporation of graphene into MoS2 has an extraordinary effect on its electrochemical performance. This work emphasises the importance of the construction of the 2D MoS2/graphene hybrid structure to prevent capacity fading issues with the MoS2 anode in lithium-ion batteries.A solvent-free, low-cost, high-yield and scalable single-step ball milling process is developed to construct 2D MoS 2/graphene hybrid electrodes for lithium-ion batteries.A solvent-free, low-cost, high-yield and scalable single-step ball milling process is developed to construct 2D MoS Recently, layer-structured molybdenum disulfide (MoS2) has attracted much attention due to its low cost, environmental friendliness, easy fabrication, and wide application in many fields, particularly rechargeable batteries.2 Even though MoS2 has potential to be used as an anode in LIBs with a high theoretical capacity of 670 mA h g−1, low electronic conductivity and large volume variations during the insertion and extraction of ions leads to poor cycling stability of the cells.2,3 To circumvent these problems, the hybridization concept is widely used, and electrochemical performance, especially cycling stability of the MoS2 anode is improved significantly. Meanwhile, carbons or other conductive materials have been integrated to form composites/hybrids with different geometries and dimensions, which could lead to improved lithium-ion storage performances in terms of both capacity and cyclic stability.4–7Electrode materials are key ingredients of any battery and the anode is a major component in lithium-ion batteries due to its electrochemical performance. Although, graphite is the most popular commercial anode material for lithium-ion batteries (LIBs), however, graphite-based anodes are unable to meet the market demands of high energy density due to the low theoretical capacity of 372 mA h g2 based electrodes is that most of the production methods produce small quantity (milligrams), which is drastically different from existing industrial processes. The materials production process is vital because, if the production technique could not be adopted by industry, it would not be possible to commercially implement the electrode materials no matter how wonderful they are. Herein, we develop a simple scalable ball-milling technique to produce a large quantity of MoS2/graphene hybrid nanosheet electrodes via an in situ generation of graphene and 2D MoS2 where bulk graphite and bulk MoS2 used as starting materials as presented in 2/graphene heterointerface is expected to enhance the electronic conductivity and store more Li+, thus results in better electrochemical properties. The electrochemical performance of the MoS2/graphene hybrid nanosheets is improved drastically over the single system of either MoS2 or graphite when used as an anode material in LIBs.In general, a common problem in preparing MoS2/graphene hybrid nanosheets, commercial bulk MoS2 (Sigma Aldrich-particle size ∼ 6 μm) and commercial bulk graphite (Sigma Aldrich-particle size < 20 μm) were used as starting materials. 4 grams of powder mixture with 2 grams of MoS2 and 2 grams of commercial graphite (weight ratio = 1 : 1) were loaded in a stainless steel milling container. Four hardened steel balls with a diameter of 25.4 mm each were also loaded to the same steel milling container where powder to ball ratio was maintained 1 : 1 . The milling container was evacuated and purged with argon gas for several times and filled with anhydrous ammonia (NH3). Anhydrous NH3 is selected in our experiment because NH3 environment protects the original structure of materials while exfoliation to nanosheets.8 Both materials were milled in a rolling ball-mill at a rotation speed of 150 rpm for 10, 20, and 40 h at room temperature under an atmospheric pressure of 300 kPa. The obtained products were denoted as MoS2-G (10 h), MoS2-G (20 h), and MoS2-G (40 h), respectively. X-ray diffraction (XRD) data were collected from powder samples on a PANalytical X'Pert powder instrument using CuKα radiation (1.54 Å) operated at 40 kV with 30 mA current. XRD data were recorded over a range of 10–80° with a step time and size of 150 s and 0.02, respectively. BET surface area of the milled samples were measured using Quantachrome Autosorb. The morphology of the milled samples was examined by scanning electron microscopy (SEM), using a Hitachi S4500 Zeiss Supra 55VP microscope operated at 3 to 10 kV. Transmission electron microscopy (TEM) investigations were performed using a JEOL JEM 2100F instrument.To prepare MoS2. The coated Cu foil was dried naturally for 10 min then in a vacuum oven at 90 °C overnight. The loading of the electrode was around 1–1.5 mg cm−2. The dried electrodes were then pressed with 5 tons of load to enhance the contact between material and copper foil. The electrochemical cells (CR2032 coin type cell) were assembled in argon-filled glove box (<0.1 ppm O2) with working electrode , polypropylene film as a separator, and Li metal foil as counter electrode. 1 M LiPF6, a mixture of ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (1 : 1 : 1) used as electrolyte. The cells were galvanostatically discharged–charged at 25 °C in the voltage range of 0.01–3.0 V at 250 mA g−1 current using a LAND battery testing system . Cyclic voltammograms (CV) were recorded using an Ivium electrochemical workstation at a scan rate of 0.05 mV s−1.For electrochemical measurements, the anode electrode was prepared by making a homogenous slurry of active material, conductive carbon additive (Super P Li™) and binder (CMC) with a weight ratio of 80% : 10% : 10% in water solvent. The slurry was then uniformly applied onto clean pieces of copper (Cu) foil with an area of 1 × 1 cm2, and ball-milled three samples of MoS2-G (10 h), MoS2-G (20 h), and MoS2-G (40 h) are shown in 2 (JCPDS: 00-006-0097). No peaks of any other phases or impurities were detected within the resolution of the measurement, demonstrating that pure MoS2/graphene hybrid can be obtained using ball milling technique.8–11 At the same time, the diffraction peaks of the graphite and MoS2 phases have a low intensity with respect to the noise level and are significantly broadened, highlighting a small crystallite size of the graphite and MoS2. As the milling time increases, the peaks of both commercial graphite and MoS2 become wider and weak, indicating the exfoliation of particles to nanosheets.8XRD patterns of the commercial graphite, commercial MoS2 and graphite, and ball milled MoS2/graphene hybrid. A typical low magnification SEM images of the pristine MoS2  hybrid shows the height surface area of 6.0 m2 g−1, whereas it was 2.0 m2 g−1 for MoS2-G (10 h) and 4.0 m2 g−1 for MoS2-G (40 h) hybrids. The result of BET surface areas is well consistence with morphology of the hybrids. It is visualised that 10 h and 40 h ball milled samples exhibit denser aggregates than that of 20 h hybrid  hybrid may deliver a high reversible capacity with a stable cycle life as compared to MoS2-G (10 h) and MoS2-G (40 h) hybrids.ine MoS2  and grapine MoS2  reveal t compare . The rel2-G (20 h) sample. Bright-field imaging of the sample reveals small flake-like dense morphology , (102), (103), and (104) for MoS2 and (002), (100), and (101) for graphene, respectively. in situ generated graphenes are composed of few-layers with a d spacing of approximately 0.35 nm, where nanocrystal of MoS2 is also clearly visible with a d spacing of approximately 0.70 nm (002).TEM examination was further carried out to evaluate the structural analysis of the MoSrphology . The cor2/graphene hybrid nanosheets was examined using CR 2032 coin-type cells in the voltage range of 0.01–3.0 V. 2 has an extraordinary effect on its electrochemical performance. All hybrid electrodes of MoS2/G exhibit excellent cycling stability with high reversible capacities of 442 mA h g−1 for MoS2-G (40 h), 553 mA h g−1 for MoS2-G (20 h), 342 mA h g−1 for MoS2-G (10 h) at 250 mA g−1 after 100 cycles, respectively. The achieved reversible capacities are almost 85% for MoS2-G (40 h), 98% for MoS2-G (20 h), and 97% for MoS2-G (10 h) electrodes after 100 cycles with respect to the 3rd cycle reversible capacities, respectively. A significant capacity fading is observed for the MoS2 electrode with a capacity retention of 37 mA h g−1 at 250 mA g−1 after 100 cycles. Such a huge improvement in cycling performance of the hybrid electrodes, particularly cycling stability, suggests that the incorporation of graphene into MoS2 crystals not only tremendously increases electronic conductivity (both interparticle and intra-particle conductivity) but also improves the ionic conductivities of the hybrid electrodes.14 However, it is interesting to note that ball milling duration in the hybrid preparation plays a critical role in their electrochemical performance. Clearly, the MoS2-G (20 h) electrode shows better electrochemical performance (in terms of capacity and stability) than that of MoS2-G (10 h) and MoS2-G (40 h) electrodes, which is related to the high surface area as well as structural integrity of the MoS2-G (20 h) electrode.The electrochemical performance of the MoS2-G (20 h) electrode is depicted in nd, 10th, 50th and 100th cycle discharge–charge curves of the electrode obtained at 250 mA g−1 within the voltage range of 0.01–3.0 V. When the electrode is discharged to 0.01 V (lithiation) and charged to 3.0 V (de-lithiation), both voltage profile exhibits typical plateaus which are consistence with the CV curves. The MoS2-G (20 h) electrode also delivers commendable initial coulombic efficiency. At the first cycle, the MoS2-G (20 h) electrode exhibits discharge/charge capacities of 485/338 mA h g−1, corresponding to the initial coulombic efficiency of ∼70% , MoS2-G (20 h), MoS2-G (40 h), and MoS2 electrodes measured at a scan rate of 0.05 mV s−1 in the voltage range 0.01–3.0 V. During the first discharge, two cathodic peaks appear between 1.0–1.25 V and 0.5–0.9 V for the MoS2-G electrodes, which can be attributed to the conversion reaction of MoS2 + 4Li+ → Mo + 2Li2S and the change in the coordination of Mo with six S atoms from trigonal prism to octahedron by inserting Li ions into the MoS2 layers  (1.0–1.25 V).2 It is observed that the cathodic peaks appeared between 0.5–0.9 V comprises broad peak, which should be correlated with the formation of a SEI (solid electrolyte interface) film on the surface of the electrodes.17 In the subsequent discharge process, the cathodic peaks are quite different from the first discharge and peaks are shifted to higher voltages and two new broad peaks appeared at 1.0 and 1.8 V, corresponding to the voltage plateau with the formation of Li2S and the association of Li ions with Mo.18 In the anodic scans, the electrodes display two peaks at 1.7 and 2.3 V, which are corresponding to the oxidation of Mo metal to MoS2 (1.7 V), while the pronounced oxidation peak at 2.3 V is due to the formation of sulfur.19,20 The MoS2 bulk electrode .2/graphene hybrid nanosheets prepared by controlled parameters could be used as an effective negative electrode for more sustainable, cost-effective Na-ion and K-ion batteries and this is to be demonstrated in our future work.The obtained preliminary results indicate that the structure of 2D MoS2 anode in lithium-ion batteries, a hybrid of nanostructured MoS2 with graphene is proposed. A simple and scalable ball milling method is developed to produce MoS2/graphene hybrid nanosheets via in situ mechanical peeling of bulk graphite and simultaneously disperse them among MoS2 nanosheets. The MoS2/graphene hybrid nanosheets effectively lead to significant improvements in electronic conductivity, structural stability, and ion diffusion, which in turn, results in excellent cycling stability is a significant advance in the field.To prevent the long-standing issue of poor cycling stability of MoSThere are no conflicts to declare.RA-010-D0RA01503B-s001


Attentional bias towards positive stimuli is considered a resilience factor for mental health and well-being. The aim of the present study was to analyze the effects of an attentional bias training for positive faces in a preventive therapeutic game for children and adolescents. The sample of 54, which consisted of children and adolescents aged between 10–16 years, played the REThink game, which included an attentional bias training level based on the visual search paradigm, where children had the task to quickly find the happy face among other angry faces. We measured mental health, and positive and negative emotions and analyzed their associations between changes in attention bias. Attentional bias indicators demonstrated acceptable reliability and results showed that increases in attentional bias towards positive faces were associated with improvements in children and adolescents’ conduct problems, hyperactivity, and peer relationship problems. Overall, our results support the protective role of training attentional bias towards positive faces as part of a preventive therapeutic game for children and adolescents. Attentional bias towards threatening stimuli is associated with the development and maintenance of anxiety disorders, as a number of reviews and meta-analysis concluded see ,2,3). Ba,3. Ba2,3Several studies also investigated the protective role that attentional bias towards positive stimuli might have for mental health e.g., ,10). For. For10])The effects of positive biases were analyzed in children and adolescents as well, although to a lesser degree. There is evidence showing that training anxious children to disentangle attention from threatening stimuli reduced stress vulnerability and anxiety . AdditioConsidering the protective role of the attentional bias towards positive emotions, and previous effects found with children and adolescents, it is important to incorporate attentional bias training for positive stimuli (ABT) into evidence-based prevention programs for children and adolescents. Furthermore, since the ABT is a computerized test, this can be easily incorporated into therapeutic games (serious games), which are a new approach to increase the accessibility of mental health programs . Shots for alcohol attentional bias [PsychMeUp [REThink game was designed to increase resilience through acquiring healthy strategies for coping with negative emotions such as anxiety, anger, and depression. REThink focuses on developing rational thinking by replacing irrational beliefs with their alternative rational believes, in a Rational Emotive Behavioral Therapy framework  and was found to have a preventive effect in healthy children and adolescents by reducing emotional symptoms and depressive mood, while increasing their emotional regulation ability [To our knowledge, previous attempts to integrate attentional bias training in an evidence-based serious game approach are scarce . In thirk (REBT ). Effica ability .REThink level. The current study is a secondary data analysis of the study regarding the effectiveness of the REThink game [REThink in training attention towards positive faces and their association with psychological changes in emotional symptoms. We proposed that changes in attentional bias would be associated with the improvements in children and adolescents’ emotional and behavioral symptoms, thus supporting the beneficial role of the attentional bias training as part of the REThink game. We thus expected that increases in attentional bias towards positive stimuli to be associated with improvements regarding children’s psychological functioning  and their mood .An ABT for positive stimuli (happy faces) was integrated as part of the final ink game . The aimN = 54) consisted of children and adolescents, aged between 10–16 years, who volunteered to participate in the clinical trial presented in David et al. [REThink condition. Six participants did not complete the initial assessment and therefore the final sample of participants who completed the program consisted of 48 children (36 girls and 12 boys) with a mean age of 13 years (SD = 2.06). Twenty-two of them were aged 9–12 and 26 were aged 13–16. There was no inclusion or exclusion criteria used in this study. Data on attentional bias from six participants were lost due to technical issues. Out of the remaining 42 participants with valid attentional bias data, eight participants did not complete the intermediary assessment. Therefore, a final sample of 34 participants was included in the main analysis of associations between changes in attentional bias and changes in emotional symptoms.The sample . With set parameters for type I error probability of α = 0.05, in a two-tailed test, and a statistical power of at least 0.80, we computed a needed sample size of 45 participants per group. In order to investigate whether attentional bias indicators are associated with changes in mood and emotional and behavioral symptoms, we computed delta change scores as a proportion of the difference between the two assessments. In the case of attentional bias, the delta change indicator reflected the proportion of change from the first session to the second session. Therefore, higher attentional bias delta change represented increased bias towards positive stimuli from the first to the second session (since the reaction time indicator decreased). For the questionnaires, the delta change indicator was computed as the proportion of change from the intermediary assessment to the post-intervention assessment, since the attentional bias training was performed between these two moments (during modules six and seven). Higher delta change indicators for the questionnaires represented decreases in scores from intermediary to post-intervention assessment. We computed within-subject adjusted Cohen’s d index of effect size, based on recorded means and standard deviations on the two points time on attention bias.All experimental protocols were approved by The Babes-Bolyai University Ethics Committee  and informed consent was obtained from the parents/their legal guardian(s) and the school principal. The study protocol was registered at ClinicalTrials.gov: NCT03308981. All methods were carried out in accordance with relevant guidelines and regulations. The sample size was estimated for the main trial to test the efficacy of the REThink is a therapeutic online game designed as an iOS application for building resilience in children and adolescents and promoting mental health. The game has a main positive character, RETMAN, whose mission is to help people on Earth against Irrationalizer, who is a “bad character” because of his powers to create unhealthy emotions and inoculate irrational thinking. The game comprises seven levels addressing specific therapeutic objectives: Level 1: identifying the emotional reactions, differentiating between basic emotions, complex emotions, and functional and dysfunctional emotions; Level 2: identifying cognitive processes; Level 3: identifying the relation between cognitive processes, emotions, and behavioral reactions, Level 4: changing irrational cognitions into rational cognitions; Level 5: building problem solving skills; Level 6: building relaxation skills; and Level 7: consolidation of previous skills and building happiness skills. The attentional bias training was included as part of Level 7. For a detailed description of the game, see the studies regarding the development and efficacy of the REThink therapeutic game [REThink game were emotional problems and emotional regulation abilities, secondary outcomes were temperament and emotional distress, and documented mechanisms were irrational beliefs. Participants played each level twice, organized in seven gaming modules, in order to consolidate the skills cultivated by each level  which was designed to consolidate previous skills and develop happiness skills. The attentional bias training used a visual search paradigm comparable to the intervention presented by Dandeneau and colleagues . For theThe difficulty of the task increased across eight blocks, comprising three trials each, as the number of total faces which appeared simultaneously increased from 9 to 30. For each block, the first trial was considered as a practice trial, so that only reaction times from the second and third trials of each block were included in the analysis. When an error was registered for a trial  participants automatically restarted the respective block, until each block was completed correctly. Only blocks without errors were included in the analysis.As with the rest of the game, participants went through the positive ABT twice, once during the sixth module, and again during the seventh module. Participants’ reaction times during the two sessions of attentional training were used as an attentional bias indicator. For each of the training sessions, we computed the mean reaction time of all second and third trials in the eight blocks, as an indicator for attentional bias. To test the reliability of the positive ABT gaming procedure, we performed a split-half analysis. We correlated the mean reaction time of second trials from all blocks with the mean reaction time of third trials from all blocks. First trials were considered practice trials and were not included in any of the analysis. The split-half reliability for the first attentional bias session (in module 6) was 0.55, and 0.39 for the second session (in module 7). Even though reliability of the attentional bias is rather low, especially for the second session, it is comparable to previous findings .Strength and Difficulties Questionnaire  is a is aStrere  is a 9- = 0.49, p < 0.01. The difference between the first and the second section is not statistically significant t(41) = 1.09, p = 0.27, with a slightly higher reaction time for the first session as compared to the second session (see d = 0.17).The attentional bias indicator  of the first training session was positively correlated with the attentional bias indicator of the second training session REThink game.We proposed that changes in attentional bias would be associated with the improvements in children and adolescents’ emotional and behavioral symptoms, thus supporting the beneficial role of the attentional bias training as part of the In order to investigate whether attentional bias indicators are associated with changes in mood and emotional and behavioral symptoms, we computed delta change scores as a proportion of the difference between the two assessments. In the case of attentional bias, the delta change indicator reflected the proportion of change from the first session to the second session. Therefore, higher attentional bias delta change represented increased bias towards positive stimuli from the first to the second session (since the reaction time indicator decreased). For the questionnaires, the delta change indicator was computed as the proportion of change from the intermediary assessment to the post-intervention assessment, since the attentional bias training was performed between these two moments (during modules six and seven). Higher delta change indicators for the questionnaires represented decreases in scores from intermediary to post-intervention assessment.r(32) = 0.48, p < 0.01, one-tailed), hyperactivity (r(32) = 0.33, p = 0.02, one-tailed), and peer relationship problems (r(32) = 0.36, p = 0.01, one-tailed) from the intermediary assessment to the post-intervention assessment. The results are showing that children and adolescents who performed better in the second attentional bias training session also registered reductions in conduct problems (r(32) = 0.28, p = 0.07, two-tailed). Changes in attentional bias were not associated with any changes in positive or functional negative emotions  experienced slightly lower improvements in their negative dysfunctional emotions. This might be in line with our previous explanation of the low associations with emotional symptoms, and might suggest that training youths to observe positive faces around them does not imply that they would experience less negative emotions and thus different mechanisms might be involved in this path .Our study has some limitations which need to be addressed. In the absence of a control group to play the game without the attentional bias training it is difficult to disentangle the effects of the other modules from the effect of the attentional bias training. Thus, future studies will need to measure outcome before and after the attention bias training level alone, in order to depict its isolated effects. Moreover, our positive attentional bias indicator was recorded during the attentional bias training, and not as a separate assessment task, which was also reflected in a rather low reliability of the attentional bias indicator. As a previous review revealed that the number of sessions has an effect on attentional bias , more seREThink online game, can easily incorporate attentional bias training components for positive stimuli. The online gamified version of attention bias training offers an accessible and promising tool that can have positive effects on the behavioral and social functioning of the youths. Overall, our results are in support of the use of attentional bias training for positive stimuli in children and adolescents as a preventive measure to be integrated in more complex therapeutic preventive programs for extending their efficacy. In sum, prevention programs for children and adolescents designed in the form of therapeutic games, such as the


In this article, comparative studies are carried out between electrochemically exfoliated graphene sheets (GSs), solvothermally synthesized graphene quantum dots (GQDs) and acid refluxed carbon nanotubes (CNTs) as an energy storage electrode nanomaterial through cyclic voltammetry (CV). The electrochemical properties of the materials are well correlated with the physicochemical characteristics obtained from Raman, Fourier-transform infrared, and absorption spectroscopy. Thin GSs (0.8–1 nm) and small size (6–10 nm) GQDs fabricated by using laboratory-grade 99% purity graphite rods resulted in promising low-cost materials at mass scale as compared to conducting CNTs. The 0D graphene quantum dots proved to be an excellent energy electrode material in an alkaline electrolyte solution compared to other carbon nanomaterials. The distinct characteristic features of GQDs, like superior electrical properties, large surface area, and abundant active sites make them an ideal candidate for utilization in supercapacitors. The GQDs exhibited an enhanced specific capacitance of 113 F g−1 in 6 mol L−1 KOH through cyclic voltammetry.Carbon nanomaterials exhibit exceptional properties and broad horizon applications, where graphene is one of the most popular allotropes of this family due to its astounding performance in every stratum vis-à-vis other classical materials. The large surface area of 2630 m Carbon nanomaterials exhibit exceptional properties and broad horizon applications, where graphene is one of the most popular allotropes of this family due to its astounding performance in every stratum vis-à-vis other classical materials. The energy density stored in SCs can be improved by increasing the specific capacitance upon the application of a particular voltage.1–3 are prime electrode materials for electric double-layer capacitors (EDLCs). The working principle of EDLCs involves non-faradaic reactions occurring on the electric double layer.4,5 The enhanced properties like large surface area, high conductivity, and cost-effectiveness are attributed to their vast use in the field of energy storage devices.6 The drawback associated with most carbonaceous nanomaterials is their hydrophobic nature which results in the agglomeration and non-uniform dispersion in any solvent.7 This leads to poor supercapacitance performance and causes hindrance to many other promising applications.8 Besides EDLCs, another branch of supercapacitors are the pseudocapacitors that operate on the faradaic reactions arising at the electrode material surface like metal oxides, conducting polymers, and their composites with carbon nanomaterials.9Carbonous materials like carbon nanotubes (CNT), carbon aerogels, graphene nanomaterials, activated carbon, carbon nanofibers, and many more1,2 The patterns of graphite layers in MWCNTs may be divided into two categories: one has a parchment-like structure with a graphene sheet coiled up around it, and the other is known as the Russian doll model, which has a layer of graphene sheet placed within a concentric structure. SWCNTs are made up of a single cylindrical carbon layer with a diameter ranging from 0.4 to 2 nanometers, depending on the temperature at which they were made. It was discovered that the diameter of CNTs increases as the temperature rises and SWCNTs can be arranged in an armed chair, zigzag, chiral, or helical patterns.1,2Multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) are two types of carbon nanotubes (SWCNTs). MWCNTs are built up from a series of coaxial cylinders, each of which is made up of a single graphene sheet and surrounds a hollow cone. MWCNTs have an outside diameter ranging from 2–100 nm, an interior diameter ranging from 1–3 nm, and a length ranging from one to several micrometers.10 Many efforts had been made in the past to produce hydrophilic graphene sheets and quantum dots (QDs); like nitric and sulfuric acid refluxing treatment to boost capacitance and other properties.11 In our recent publication, we have synthesized low-cost, solution-processable, and high-quality graphene sheets (GSs) and graphene quantum dots (GQDs) using laboratory-grade graphite electrodes.8 GQDs are graphene sheets with quantum-scale dimensions, i.e., 0D nanomaterials, with substantially larger specific surface areas and more accessible edges than graphene sheets.7 In this report, comparative energy storage properties of MWCNT, SWCNT, graphene, and its quantum dots are studied through electrochemical cyclic voltammetry (CV) measurements. Although the energy storage properties of carbon nanomaterials in the individual and composite forms are explored extensively in the past, systematic comparison drawn amongst them is scarcely reported in the literature. In addition, electrochemical features are correlated with the morphological patterns, solubility, structural defects, and oxygen functionalities of carbon materials. There are many reports available implicating graphene nanomaterials to be better energy electrode materials than CNTs, but relative comparative study with in-depth reasoning is rather scarce in the literature.Graphene is one the most important member of the carbon family due to its enhanced performance in every field.2.2.1.−1 KCl] and polyvinylidene fluoride (PVDF) from Sigma-Aldrich; laboratory-grade graphite rod [99.9% pure] from local vendor; 0.22 μm membrane filter and dialysis membrane-50 (LA387-10MT) from Whatman and Himedia; N-methyl-2-pyrrolidone (NMP), nitric acid (HNO3), dimethylformamide (DMF) and ethylenediamine (en) from Thermo Fisher Scientific; potassium hydroxide pellets (KOH), sodium chloride (NaCl) salt and ortho-phosphoric acid (H3PO4) were procured from Merck, India. Single-walled carbon nanotubes (SWCNTs)  from Carbon Solutions Inc., and multi-walled carbon nanotubes (MWCNTs) from Chengdu Organic Chemicals Co., China were purchased.All chemicals used were of analytical reagent grade and double distilled (DI) water was used to make the solutions. Platinum (Pt) mesh, reference electrode Ag/AgCl [3 mol L2.2.−1 HNO3 for 5 h at 100 °C to acid functionalize and remove unwanted metal impurities.12 Further, washing was performed through ultrasonication and centrifugation with DI water and ethanol to remove acid and bring the pH neutral. Many methods are reported in the past to obtain high-quality GQDs, showing enhanced properties than carbon-quantum dots.13–16 In addition, graphene sheets and quantum dots were prepared according to the details published in our earlier report.8 The protocol followed for energy storage measurements is also discussed below. Briefly:The purchased SWCNTs and MWCNTs powder were refluxed in 5 mol L−1 NaCl electrolyte at room temperature (RT) under constant DC potential ranging from 2–10 V using Solartron 1280C. The obtained product solution was rinsed completely to obtain neutral pH, sonicated for 2 h to get homogenous graphene suspension, and filtered through a 0.22 μm filter membrane for thin GSs.(a) Graphene sheets (GSs): graphite rod (anode) was exfoliated in an electrolytic cell with Pt mesh as a cathode in 0.5 mol L−1 HNO3 acid at 100 °C for 24 h under continuous stirring to purify and reduce the lateral flake size. The suspension was washed thoroughly to remove the acid and bring the pH neutral.(b) Purified graphene sheets (PGS): the above derived GSs (50 mg) were refluxed in 5 mol L−1 H3PO4  and 30 mL ethylenediamine. The suspension was probe sonicated for 2 h and transferred to a 100 mL Teflon lined stainless steel autoclave, heated at 200 °C for 8 h. The resultant consisted of black sediment carrying larger graphene particles with brown supernatant as GQDs. The larger graphene nanoparticles were separated by vacuum filtration with a 0.22 μm filter membrane and dialysing the collected filtrate over DI water in a dialysis bag for 24 h to obtain GQDs.(c) Graphene quantum dots (GQDs): the acquired diminished size PGS was suspended in a mixture of 5 mol L2, −1 KOH at room temperature (RT).(d) Cyclic voltammetry (CV) measurements: the energy-related electrochemical studies were carried out using the three-electrode system with MWCNT, SWCNT, GQDs, and PGS as working electrodes (WE), platinum wire as a counter electrode (CE), and Ag/AgCl as reference electrode (RE), respectively using Solartron 1280C. Further, WEs were fabricated by dissolving 90 wt% (1 g) active material in a mixture of 10 wt% (0.1 g) PVDF (adhesive) and 100 μL NMP (dispersion medium) creating a free-standing film  The morphology was observed using a field emission scanning electron microscope . The cluster of SWCNT and MWCNT possess diameters of 2–5 nm and 2–80 nm with lengths in micrometres, respectively as illustrated in −1) is related to disordered structural defects ,17–19 while the G band (∼1584 cm−1) is connected with the first-order scattering of the E2g mode found for sp2 carbon domains. ID/IG (sp3/sp2) is the integrated area ratio, a small value of which signifies low defects and high crystallinity in the carbonaceous sample. The defect density was reduced in GQDs (ID/IG ∼ 0.78) obtained after the high temperature and pressure treatment on PGS (ID/IG ∼ 1.32) as shown in ID/IG ∼ 1 and ∼zero defects in SWCNTs due to fewer oxygen functional groups attached during chemical treatment. SWCNTs, GQDs, and PGS all have tangential (G-band) multi-feature at higher frequencies, but in the case of current MWCNTs, it indicates that the innermost nanotube diameter is less than 2 nm.1,2(b) A micro-Raman spectrometer  was used to produce a Raman spectrum through an Olympus 100× objective lens with a spot size of 1.19 μm, an excitation wavelength of 514 nm, and a 4 mW optical power of an argon-ion laser. The D band (∼1353 cm−1), C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>O (carboxyl group: 1670–1710 cm−1), C–O–C stretching (epoxy group: 1080–1255 cm−1), CC (sp2 hybridised: 1500–1600 cm−1), CO2 (2300–2400 cm−1) and these make them soluble in solvents. The presence of an intense peak of CO2 group can also be ascribed to the sample contamination. The ionisation of abundant oxygen groups usually results in GQDs aqueous dispersion being quite stable.20 The graphene sheets (PGS) possess an increased number of oxygen functional groups connected to them after reflux treatment vis-à-vis source graphene sheets (GSs). The dispersion of virgin SWCNTs and MWCNTs in water, on the other hand, is unstable and tends to cluster, therefore the CNTs were acid refluxed prior to the use in an application.1,2(c) Fourier-transform infrared spectroscopy  was used to investigate the functionalized groups attached to the carbon nanomaterial pellets. The FTIR spectra  of MWCNT−1. In all cases, the concentration of nanomaterial dispersed was 0.5 mg mL−1 in DMF solvent through bath sonication for 0.5 h. The enhanced solubility in water and other solvents can be attributed to oxygen-containing functionalities  decorated on the carbon materials as studied in FTIR analysis.21,22 The degree of residual conjugation (π–π* transition) is determined by the peak around 227–231 nm range and n–π* transition of carbonyl groups is responsible for the shoulder at about 300 nm. Both the absorption peaks are observed in graphene nanomaterials (PGS and GQDs) and in the case of CNTs, the structural peaks can be seen around 250 nm (23(d) Absorption spectra were obtained using a UV-visible spectrophotometer  with a path length of 1 cm and a scan rate of 120 nm mind 250 nm . These o3.2.24 Only the outermost section of SWCNTs 26,27 and metal oxide composites such ZnO28 and MnO2.29 Graphene nanosheets  assembled to a multilayer carbon demonstrated volumetric capacitance of 157.4 F cm−3.35 Breaking the nanosheets into graphene quantum dots . CV experiments were performed within a potential window of −0.3 to +0.3 V, 0 to −0.4 V, −0.7 to + 0.3 V, and −0.4 to +0.05 V vs. Ag/AgCl for MWCNT, SWCNT, GQDs, and PGS, respectively . These researches assisted in the knowledge of the link between the structural and electrochemical characteristics of carbon-based electrodes, pointing to the possible use of carbon nanomaterial films in biosensing, energy conversion, biomedical, and other electronic systems.ectively .1,2 as observed in all carbon nanomaterials. EDLCs have some problems including unsatisfactory low specific energy density and poor rate performance due to their limited accessible storage sites. Although a pseudocapacitive contribution is also present, represented by faradaic redox signals where current changes upon voltage scan.39,40 The capacitive nature remains preserved even at higher scan rates with a great current density as observed in Cs in F g−1) was determined using the equation below:41Q is the average charge during a complete redox reaction, m is the mass of active material and ΔV is the potential window. The ratio of the cathodic peak current (Ipc) to the anodic peak current (Iac) is ∼1, indicative of comparatively swift, electrochemically quasi-reversible electron transfer kinetics. Anodic current increases directly with increasing square root of the scan rate,41 as shown in The rectangular shaped voltammogram with large current separation between the forward and reverse scans, symmetric in both anodic and cathodic directions indicates electrochemical double layer capacitive behaviourThe relationship between the scan rate and peak current was obtained through linear fitting analysis in the form of a regression equation drawn below:(a) (b) (c) (d) −1 for SWCNTs and MWCNTs,1,2 which is lower than graphene despite the former's higher conductivity; due to random orientation, and bundling of the former. The CNTs electrode showed no peaks, as one would anticipate from a carbon material that exhibits the double layer capacitor behaviour. Graphene sheets are extremely electroactive and have rapid electron transfer kinetics due to their unique structural and electrical characteristics.5 The unusual electrical structure of PGS is responsible for the quick heterogeneous electron kinetics between the electrode and the solution. At normal temperature, the graphene sheet behaves as a semimetal or a zero-bandgap semiconductor with extraordinarily high electron mobility, which might improve electron transport when its plane is directly in touch with the electrolyte.27 In contrast, monolayer GQDs showed high surface area, uniform size distribution, and great porosity resulting in high specific capacitance vis-à-vis graphene sheets and CNTs.These results are in line with the literature's prediction of 14 to 80 F g8 In sample PGS, more oxygen functionalities are decorated as compared to source GS due to acid reflux therapy. Further, the synthesis of GQDs in the oxidative acid hydrothermal atmosphere resulted in a combination of monolayer and few-layer GQDs. Deoxygenation and reduction arise due to the pressure induced during the hydrothermal heating process and oxygen functional groups are introduced on the edges because of the presence of protic acid H3PO4 (aqueous) as solvent. The stated observations are confirmed with FTIR analysis described in Section 3.1(c). The electron transmission process on graphitic materials is greatly accelerated by the presence of edge-plane imperfections.7 The material with the high D/G ratio obtained from Raman spectra (8The electrochemical exfoliation for forming GSs at a relatively high voltage of 10 V has effectively inspired the deoxygenation of functional groups along with GSs. spectra  offers t4.The high structural purity and enhanced solubility revealed excellent specific capacitance of GQDs vis-à-vis PGS, MWCNT, and SWCNT. This implies that the high defect density, large surface area, and high porosity of graphene quantum dots result in superior specific capacitance, thereby proving to be a better energy electrode nanomaterial candidate. GQDs showed higher current density and capacitance vis-à-vis other carbon materials in the solutions indicating promising materials for supercapacitors and lithium-ion batteries. Such energy storage materials are proving to be a boon for electronic device technology. In addition, this paper demonstrated intra-comparison between the carbon nanomaterials rather than differentiating it from the data reported in other articles.There are no conflicts to declare.