This exceptional performance underscores the potential of the algae-graphene composite as a highly efficient and durable electrode material for supercapacitor applications.This study focuses on the synthesis and characterization of supercapacitor materials derived from pyrolyzed natural compounds. Four compounds were investigated: methylcellulose with lysine (ML), methylcellulose with lysine-graphene composite (MLG), algae (A), and algae-graphene composite (AG). The pyrolysis process was utilized to convert these natural compounds into carbon-based materials suitable for supercapacitor applications. The properties of the resulting materials were analyzed extensively to evaluate their potential as supercapacitor electrodes. The electrochemical performance, including specific capacitance, cyclic stability, and rate capability was measured using various characterization techniques. The effects of incorporating graphene into the lysine-methylcellulose and algae matrices were also studied to explore the enhancements in supercapacitor performance. In both cases, the addition of graphene resulted in a positive effect. Among all the materials investigated, the algae-graphene composite exhibited the most favorable properties, demonstrating a specific capacitance of 192 F g They have the potential to bridge the gap between conventional capacitors and batteries, offering a unique combination of energy and power delivery for various applications, including portable electronics, electric vehicles, and renewable energy systems5. The performance of supercapacitors relies heavily on the properties of the electrode materials2. Carbon-based materials have been widely explored as electrode materials for supercapacitors due to their high surface area, good electrical conductivity, and excellent electrochemical stability10. Traditional carbon sources, such as activated carbon, have been extensively utilized12. However, there is growing interest in developing sustainable and cost-effective electrode materials derived from natural compounds16. Pyrolysis, a thermal decomposition process in the absence of oxygen, has emerged as a promising method for synthesizing carbon-based materials from natural precursors. Pyrolyzed materials exhibit unique structural and electrochemical properties, making them attractive options for supercapacitor applications18. The use of natural compounds as precursors offers several advantages, including abundant availability, low cost, and environmental friendliness19.Supercapacitors, also known as electrochemical capacitors or ultracapacitors, have gained significant attention as promising energy storage devices due to their high power density, fast charge–discharge rates, and long cycle life compared to traditional batteries20 demonstrated that pyrolyzed rice husks exhibited a specific capacitance of 278 F g−1 in a potassium hydroxide electrolyte, highlighting the impressive electrochemical performance achievable with bio-waste materials. Furthermore, Lv and colleagues21 explored the pyrolysis of chitosan, resulting in carbon-based materials with a specific capacitance of 306.4 F g−1 in 6 M KOH electrolyte, thus emphasizing the versatility of natural polymers for supercapacitor applications. Additionally, the work of Yi et al.22 on the pyrolysis of lignin-based materials showed a specific capacitance of 133 F g−1, demonstrating the viability of lignocellulosic biomass as a renewable electrode precursor. These examples underscore the burgeoning interest in sustainable and environmentally friendly electrode materials derived from readily available natural sources. The continuous investigation into the electrochemical behavior and properties of these materials promises to propel energy storage technology to new heights, with potential applications spanning a wide range of industries.Our study is situated within the context of the latest advancements in pyrolyzing diverse natural sources to serve as supercapacitor electrodes. Recent research has witnessed significant strides in this domain, showcasing the remarkable potential of materials derived from natural compounds. For instance, studies by Liu et al.In this study, the synthesis and characterization of supercapacitor materials derived from pyrolyzed natural compounds was conducted. Specifically, four compounds were investigated: lysine with methylcellulose, lysine with methylcellulose-graphene composite, algae, and algae-graphene composite. Lysine, an essential amino acid, and methylcellulose, a biodegradable polymer, have shown potential in various applications due to their unique physicochemical properties. Algae, on the other hand, are abundant and renewable biomass resources that have gained attention for their potential use in energy storage systems. The incorporation of graphene, a two-dimensional carbon material with exceptional electrical conductivity and mechanical strength, offers the opportunity to enhance the performance of the resulting supercapacitor materials. Additionally, comprehensive studies utilizing solid-state physics techniques will be conducted alongside the electrochemical investigations. These investigations will provide valuable insights into the structural and morphological properties of the pyrolyzed natural compounds and their composites. Techniques such as scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption at a low temperature, and elementary analysis will be employed to characterize the crystalline structure, surface morphology, and nanoscale features of the materials. These complementary studies will offer a comprehensive understanding of the relationship between the structural properties and the electrochemical performance of the synthesized materials, facilitating the design and optimization of advanced supercapacitor materials. This study aims to investigate the electrochemical properties of these pyrolyzed natural compounds and evaluate their potential as electrode materials for supercapacitors. By analyzing the specific capacitance and cyclic stability of the synthesized materials, we strive to gain insights into the performance enhancements achieved by incorporating graphene and utilizing different natural precursors.SEM images provide crucial insights into the size, shape, and internal structure of materials. In this study, SEM analysis was utilized to characterize the morphology of the composite materials, and the results are presented in Fig. 24. The disorder-induced band resulting from vacancies or dislocations in the graphene layer and at its edge (D-band), the band associated with graphene in graphite (G-band), and the band related to the graphene layer (2D-band) observed in the Raman spectra . The ratio of 2D to G band intensities for ML, MLG, A, and AG is 0.31, 0.40, 0.30, and 0.36, respectively. This I2D/IG intensity ratio is less than 1, indicating the presence of a few graphene layers.Raman spectroscopy is a leading method used to characterize carbon materials2 g−1 and 2,478 m2 g−1, respectively. The total pore volume determined at maximum p/po for the samples with the highest SBET is 1.82 cm3 g−1 and 1.11 cm3 g−1 for samples ML and A, respectively. The physical morphology of the two samples synthesized with graphene was decreased to 1,184 m2 g−1 and 1,518 m2 g−1 for MLG and AG, respectively. However, this SBET for MLG and AG is still very high, and the total pore volume was 0.99 cm3 g−1 and 0.75 cm3 g−1, respectively. The shape of the obtained nitrogen adsorption isotherms  with a small hysteresis loop at a relative pressure of 0.4–1.0. The large surface area and significant share of micropore size (less than 2 nm) visible on pore size distribution curves  method. The ML and A samples exhibited the highest specific surface areas when nitrogen-doped carbons obtained from methylcellulose with lysine or algae were used as substrates, with BET values of 2,049 mThe elemental composition of samples ML, MLG, A, and AG, with or without the participation of commercial graphene, was determined using an elemental combustion analysis. Similar levels of carbon values were obtained for ML (78.10% by weight) and A (80.87% by weight) samples, but the highest carbon content was characterized by samples whose synthesis used graphene MLG (90.38% by weight) and AG (84.14% by weight). The addition of commercial graphene during the synthesis contributed to obtaining a material with a carbon content higher by 4 or 16% compared to the material where commercial graphene was introduced mechanically before the carbonization process. The nitrogen content of lysine and algae as good nitrogen-doped carbon precursors is very high after high-temperature treatment, at 4.71% by weight and 3.75% by weight for ML and A, respectively. On the other hand, the nitrogen content decreased for samples with graphene to 1.79% and 1.39% by weight for MLG and AG, respectively. For all analyzed samples, the hydrogen content reaches low values from 0.94 to 1.06% by weight. The percentages of elements obtained by elemental analysis are shown in Table To confirm the chemical state of the atoms present on the surface of the materials obtained, X-ray photoelectron spectroscopy analysis was performed. The low-resolution broad-band spectra for MLG and AG hybrid materials are shown in the energy range from 0 to 1,200 eV Fig. a,b.Figur2) occurring at a bond energy of 284.3 eV are present in the studied structure. The energy band at 285.0 eV indicates the presence of a C–C bond (sp3). C–O–C and/or C–OH type bonds are also present in the obtained materials, which was confirmed by a band at a binding energy of 285.9 eV. The band at energies equal to 286.8 eV corresponds to C=O and/or O–C–O bonds, and at energy 288.0 eV is characteristic of O–C=O-type bonds. In addition, the band at energies equal to 289.7 eV and 292.1 eV can be attributed to shake-up excitation from sp2-type carbon. The XPS spectrum for the tested samples in the N1s region , methylcellulose with lysine-graphene composite (MLG), algae (A), and algae-graphene composite (AG). The CV curves for each sample were recorded within a voltage window of − 0.1 V to + 0.8 V  and galvanostatic charge–discharge (GDC) experiments. A three-electrode system was employed, comprising an Ag/AgCl/3 M KCl reference electrode, the obtained carbon-based materials as the working electrode, and a Pt mesh counter electrode. The electrochemical measurements were carried out using a 0.2 M KBET)36. Traditional supercapacitor research has sought to maximize surface area to achieve higher capacitance. However, the diminishing returns associated with this approach have become evident as the theoretical maximum limit for surface area utilization seems to have been reached35. The discovery that materials with graphene additives exhibit improved capacitance, even with a smaller surface area, challenges the notion that surface area is the sole driver of enhanced performance. Other factors, such as the conductivity and structural characteristics introduced by graphene, may contribute to the increased electrochemical capacitance36. The exceptional electrical conductivity of graphene facilitates efficient charge transfer and electron transport within the electrode, enabling a higher capacitive response. Additionally, the unique structural properties of graphene, such as its two-dimensional layered structure and large aspect ratio, may create favorable conditions for ion diffusion and accessibility to active sites, thereby enhancing the charge storage capability38. Therefore, the race for achieving the highest surface area is no longer the sole priority in supercapacitor research. It has become increasingly evident that, besides specific surface area, other factors play a crucial role in determining the capacitance of supercapacitor materials. These factors include the distribution of pore sizes within the material and, equally importantly, the nature of the electrolyte used. The latter consideration is particularly significant, as it involves matching the size of the ions in the electrolyte to the pore size within the material. In this context, optimizing the pore size distribution has gained prominence because it influences ion transport and accessibility to the electrode's surface. A well-balanced pore structure can facilitate efficient ion diffusion, leading to enhanced capacitance and improved charge–discharge performance. Furthermore, the choice of electrolyte plays a pivotal role in dictating the supercapacitor's overall performance. The ion size in the electrolyte should ideally align with the pore size distribution within the electrode material. This alignment ensures that ions can readily access and interact with the available surface area, maximizing the electrochemical capacitance. In essence, achieving high capacitance in supercapacitors is not solely about increasing the surface area; it also involves optimizing pore size distribution and carefully selecting an electrolyte that matches the pore size characteristics, creating an effective synergy between these factors for superior energy storage capabilities. Thus, the incorporation of graphene has opened up new avenues for improving electrochemical performance, demonstrating that factors beyond surface area can significantly influence the capacitance of electrode materials. Moreover, among the investigated materials, the highest capacitance after 100 charge–discharge cycles was observed for the material containing pyrolyzed algae with graphene  resulted in a reduction in resistance. This finding underscores the positive impact of graphene on enhancing charge transfer kinetics within the electrode–electrolyte interface, which is valuable for improving the overall performance of supercapacitors. This specific combination exhibited exceptional electrochemical performance, highlighting the synergistic effects between pyrolyzed algae and graphene in terms of charge storage. In each case, an increase in capacitance was observed with successive cycles, indicating a progressive improvement in the electrochemical performance of the materials. However, to gain a deeper understanding of this phenomenon, materials containing graphene were chosen for subsequent studies.This absence of a semicircle indicates a relatively small charge transfer resistance, which can be attributed to the porous structure of the materials40.To assess the long-term repeatability of the observed phenomenon and to determine if the capacitance value continues to increase over an extended period, electrochemical measurements were conducted over 1,000 charge–discharge cycles. The results are depicted in Fig. −1 for MLG and AG, respectively. These curves provide insights into the charge storage and discharge behavior of the supercapacitor electrodes over a long cycling period. In the two-electrode configuration, it is observed that there is no significant increase in capacitance with successive cycles, as previously observed in the three-electrode setup. However, it is worth noting that there is still an increase in capacitance throughout the cycling test, especially up to approximately 500 cycles.To evaluate the stability of symmetric supercapacitors based on the materials with methylcellulose-graphene composite and algae-graphene composite, multiple charge–discharge cycles were conducted in a two-electrode configuration. The supercapacitors underwent an extensive cycling test of 10,000 cycles to assess their long-term stability and performance. Figure The absence of a pronounced capacitance increase in the two-electrode configuration can be attributed to several factors. Firstly, the closer proximity between the two electrodes in this setup may result in a limited diffusion of ions and a reduced accessibility of active sites, thus inhibiting the full utilization of the electrode materials' capacitance. Moreover, a vacuum sealer is commonly used during the fabrication of prototype supercapacitors, which likely leads to a quicker impregnation of the carbon electrodes with the electrolyte. This accelerated impregnation may result in a faster initial capacitance increase during the early cycles.Despite the absence of a continuous capacitance increase, the observed retention of capacitance up to around 10,000 cycles indicates the stability and durability of the MLG and AG materials in the symmetric supercapacitor configuration. This capacitance retention suggests that the materials can still provide reliable and sustainable energy storage performance over several cycles.−1. The combination of algae and graphene in the composite material seems synergistic, leading to an enhanced capacitance compared to the other studied materials. The presence of graphene contributes to improved electrical conductivity, facilitating efficient charge transfer and higher charge storage capacity. Meanwhile, the unique properties of algae, such as its high surface area and porosity, likely provide additional active sites for electrochemical reactions, further enhancing the capacitance43. For comparative analysis, three representative charge–discharge cycles are presented: the first cycle, the cycle at which the maximum electrochemical capacity was achieved, and the final cycle. These cycles offer insights into the electrochemical behavior and performance of the studied materials over the course of the testing  material exhibited the highest capacitance, reaching a maximum value of 241 F gsee Fig.  inset. I−1. To determine the charge transfer process mechanism, current density (j) versus potential (v) plots  plots  and the cheap and widely available two hard templates K2CO3 and CaCO3. Carbon materials from natural sources were synthesized in two series. In the first series, natural carbon sources methylcellulose and lysine were used, along with a hard CaCO3 template in a weight ratio of 1:1:1. In the next step, a solution of K2CO3 at a concentration of 11% m/v was prepared and added to the mixture, which was then mixed mechanically and intensively until a homogeneous mass was obtained. In the second series, 100 mL of K2CO3 solution (concentration of 11% m/v) was added to 5 g of green algae and stirred until a homogeneous solution was obtained. In both series, the resulting mass was allowed to dry at 100 °C to evaporate water. The samples were then pyrolyzed at 800 °C for 1 h, with a heating rate of 10 °C min−1 in a nitrogen flow. After the pyrolysis process, the final product was treated with concentrated hydrochloric acid to remove residual carbonates. The samples were then washed with water and dried in an electric dryer. The second series was based on the use of the green algae, Chlorella vurgalis. The synthesis steps were analogous to the first series, and the mass ratio of the compounds was also the same. Commercial graphene nanoplatelets (G) with a specific surface area of 750 m2 g−1 and electrical conductivity of approximately 1,400 S cm−1  were added to both series to improve the conductive properties at a mass ratio of 0.2 to the carbon material. The samples in the first series were marked as ML and MLG, where M was designed for methylcellulose and L for lysine used during the synthesis. The samples in the second series were named A and AG, where A is algae. In both series, G is commercial graphene.Carbon materials were prepared using an uncomplicated pyrolysis method using natural sources  was determined using the Brunauer–Emmett–Teller (BET) method, which calculates the surface area based on the adsorption isotherm data. Additionally, the total pore volume  and pore size distribution were determined using the Density Functional Theory (DFT) method, providing information about the porosity of the carbon materials. To analyze the elemental composition of the samples, a bulk combustion analysis was conducted to measure the carbon, nitrogen, and hydrogen contents. This analysis provides quantitative information about the relative amounts of these elements present in the carbon materials. X-ray photoelectron spectroscopy (XPS) measurements were performed using a monochromatic Al Kα excitation source operated at 1486.6 eV. The survey spectra and high-resolution spectra were collected using pass energies of 0.5 eV and 0.1 eV, respectively. The spectra were referenced to the C1s neutral carbon peak at 284.8 eV, allowing for the characterization of the carbon-containing functional groups and their chemical states.Surface analysis of the samples was conducted using a scanning electron microscope (SEM) type 1430 VP at an accelerating voltage of 30 kV from LEO Electron Microscopy Ltd, England. This SEM instrument allowed for detailed examination and characterization of the surface morphology and features of the materials. Raman spectra were recorded using a Raman spectrometer  with a green laser (532 nm) as the excitation source. Raman spectroscopy allowed for the investigation of the materials' vibrational modes and molecular structure, providing insights into their chemical composition and bonding configurations. A detailed surface structure and features analysis was conducted to gain insights into the material's physical characteristics. The sorption of nitrogen was performed using an ASAP2020 Plus instrument from Micromeritics. Prior to the sorption measurements, the samples underwent a vacuum outgassing process at 200 °C for 24 h to remove any adsorbed contaminants. The specific surface area , with an Ag/AgCl (3 M KCl) reference electrode and a platinum mesh counter electrode. All electrochemical experiments were performed using a potentiostat/galvanostat (BioLogic VSP 2078) and involved cyclic voltammetry and galvanostatic charge–discharge (GCD) techniques. During the CV measurements, the potential was scanned from − 0.1 V to + 0.8 V vs. Ag/AgCl (3 M KCl) at a scan rate of 50 mV s−1. This range allowed for the investigation of the electrochemical behavior of the electrode materials. GCD tests were conducted within the same potential range, with a current density of 2.0 mA cm−2. The charge–discharge cycles provided insights into the energy storage capacity and performance of the synthesized materials. Moreover, EIS was performed for all obtained electrode materials in a frequency range between 20 kHz and 1 Hz with a voltage amplitude of 10 mV at an open circuit potential.The electrode materials were prepared by suspending 20 mg of the samples in a mixture of 0.75 mL distilled water, 0.2 mL isopropanol, and 0.05 mL of a 5% aqueous Nafion solution. The resulting suspension was sonicated in an ultrasonic bath for 60 min to ensure proper dispersion. Subsequently, the prepared mixture was deposited onto a polished surface of a glassy carbon electrode with a diameter of 1.5 mm and allowed to dry in an oven at 60 °C for a few minutes. For the electrochemical measurements, a three-electrode configuration was employed. The electrolyte used was a 0.2 M K−1 K2SO4 aqueous electrolyte, was placed between the electrodes. The GF was coated with a mixture containing the tested carbon materials (MLG and AG), which was then dried at 40 °C for 6 h. The mass loading of the carbon materials onto the GF was determined by measuring the weight difference of the electrode material before and after applying the mixture. An analytical balance, specifically the RADWAG XA 82/220.4Y PLUS with an accuracy of 0.01 mg, was utilized for this measurement. The mass loading was found to be approximately 4.27 mg cm−2 for MLG and 5.38 mg cm−2 for AG. The thickness of the layers was about 30 µm. Subsequently, the casing foil was sealed around three sides using a plastic foil welder. Finally, the entire setup was securely sealed using a vacuum packing machine . This construction process ensures the assembly of a symmetric supercapacitor with the MLG and AG materials as the electrodes. The use of flexible graphite foils provides mechanical support and flexibility to the device, whereas the fiberglass separator soaked in the electrolyte facilitates ion transportation between the electrodes while preventing direct contact. The sealing of the setup using the plastic foil welder and vacuum packing machine ensures the encapsulation and protection of the supercapacitor, maintaining its integrity and preventing moisture or air ingress. By employing these construction steps, a reliable and well-protected symmetric supercapacitor setup is achieved, allowing for further electrochemical characterization and performance evaluation of the MLG and AG materials. The galvanostatic charge and discharge tests  were performed for the symmetric supercapacitor. Charge and discharge measurements were made at a current density of 5 A g−1, with an electrochemical voltage range of 0 to 0.9 V. The specific capacitance (Csp) was calculated using the galvanostatic charge–discharge curves provided and Eq. .To construct a symmetric supercapacitor, two flexible graphite foils (GF) were combined with the obtained material electrodes. A fiberglass separator, soaked in a 0.2 mol L−1 over a polarization range of 0 to 0.9 V. A floating test was also conducted to evaluate the most promising stability for the carbon material, as detailed in reference54. The procedure involved conducting five galvanostatic charge–discharge cycles at maximum voltage after every 10 h of aging. The specific capacitance was then calculated. This series of sequences was repeated 10 times, totaling a floating time of 100 h.The charge–discharge measurements were also carried out for MLG and AG at current densities ranging from 1.0 to 10 A gThis article investigates the utilization of pyrolyzed natural compounds for supercapacitor applications, with a particular focus on the impact of graphene addition on the electrochemical performance. Four materials were studied: lysine with methylcellulose, lysine with methylcellulose-graphene composite, algae, and algae-graphene composite. The results demonstrate that incorporating graphene into the lysine-methylcellulose and algae matrices significantly improved the electrochemical properties of the resulting supercapacitor materials. Despite the graphene-infused materials having a smaller specific surface area compared to the carbon materials without graphene, they exhibited enhanced capacitance. The superior electrochemical performance observed in the graphene-enhanced materials can be attributed to several factors. Firstly, graphene, with its high electrical conductivity, facilitates efficient charge transfer and electron transport within the electrode. This results in improved capacitive behavior and enhanced energy storage capacity. Furthermore, the graphene reinforcement provides mechanical stability to the electrode materials, preventing structural degradation during repeated charge–discharge cycles. The resulting electrodes exhibit excellent cyclic stability and retain their electrochemical performance over extended operation. Thus, the findings of this study highlight the significant role of graphene in enhancing the electrochemical properties of pyrolyzed natural compound-based supercapacitor materials. Despite having a smaller specific surface area, the addition of graphene leads to improved capacitive behavior, higher specific capacitance, and excellent cyclic stability.


We implemented a semi-empirical pseudopotential (SEP) method for calculating the band structures of graphene and graphene nanoribbons. The basis functions adopted are two-dimensional plane waves multiplied by several B-spline functions along the perpendicular direction. The SEP includes both local and non-local terms, which were parametrized to fit relevant quantities obtained from the first-principles calculations based on the density-functional theory (DFT). With only a handful of parameters, we were able to reproduce the full band structure of graphene obtained by DFT with a negligible difference. Our method is simple to use and much more efficient than the DFT calculation. We then applied this SEP method to calculate the band structures of graphene nanoribbons. By adding a simple correction term to the local pseudopotentials on the edges of the nanoribbon (which mimics the effect caused by edge creation), we again obtained band structures of the armchair nanoribbon fairly close to the results obtained by DFT. Our approach allows the simulation of optical and transport properties of realistic nanodevices made of graphene nanoribbons with very little computation effort. The electronic properties of low-dimensional materials are unique due to unprecedented properties that are unparalleled by those in bulk counterparts ,2. A sciAb initio formalism such as density-functional theory (DFT)  has beenx-y plane) and Gaussian functions along a non-periodic  ,15 preseDFT is a widely used computational method for studying the electronic structure of AGNRs ,18. DFT Empirical methods, on the other hand, offer an alternative approach to studying AGNRs . These mGraphene nanoribbons (GNRs) ,23,24,25In electronics, AGNRs offer tunable bandgaps and unique edge states, making them potential candidates for high-performance transistors and logic devices . AGNRs aIn this paper, we implement a more sophisticated semi-empirical pseudopotential method (SEPM) within the planar basis to study the atomic and electronic structure of 2D systems, using graphene and armchair graphene nanoribbons as examples. The applications of the currently developed SEP include optical and transport properties of graphene and related structures such as graphene nanoribbons and various junction devices.To calculate the band structures of 2D materials in the semi-empirical pseudopotential (SEP) model, it is more efficient to adopt a planar basis. The basis consists of localized finite-element functions, i.e., B-splines  in the zThe first derivative of the B-spline of order z, and The derivative of B-splines of order κ is a linear combination of B-splines of order Throughout this paper, we work in atomic units, where energy is in units of Ry, and distance is in units of Bohr. The Hamiltonian of the system in the ultrasoft pseudopotential approach  is givenA is the surface area of the sample. The overlap matrix elements between two planar basis functions are given by the following:Here, R denotes a bulk lattice vector, and r. For charge-neutral systems, there is a counter long-range term in The local pseudopotential of the crystal is given by the following:For fitting empirical pseudopotentials of bulk materials, one adjusts the Fourier transform of the potential of ulations . To undeulations ,41,42. Worted in . The DFTorted in  were cheorted in , and theorted in  and paraorted in . The fitThe second term of Equation (14) denotes the difference Note that the chosen form of The best-fit parameters for short-range correction functions defined above are listed in the first row of Combining all above, the total local potential is given by the following:For convenience, z-axis used to define the B-spline basis. To check if the real space form of the local pseudopotential It is seen that the result obtained by SEP matches the corresponding DFT results very well. In z-dependence of the bond-charge contribution. Here, z-axis at To determine this contribution, we fit the difference of the local potential obtained by DFT and by SEP, i.e., The net local potential of graphene, The best-fit parameters The semi-empirical pseudopotential contains both local and non-local terms. The non-local pseudopotential contains angular momentum and energy-dependent terms . Incorpol (USPP) . The fitFor the second 2P orbital K;BiHere, This expression is identical to (39) except that the energy parameters put data ,16 to caz-axis. By adopting the B-spine basis along the z-axis and taking symmetric and antisymmetric combinations of these basis functions, we can decouple the eigenstates of the Hamiltonian within the symmetric and antisymmetric basis sets for any wave vector in the 2D plane. This significantly improves the speed of computation for the band structures. We found that using a direct solver for diagonalization becomes even faster than the iterative solver based on the conjugate-gradient (CG) approach [The formulas derived above can be extended to other two-dimensional materials beyond graphene, such as transition-metal dichalcogenides. Due to the inversion symmetry in graphene, all matrix elements become real. Furthermore, there is a mirror symmetry for the approach  for thisThe all-electron (AE) Bloch states of graphene are written as follows:equation  reads asWe apply the current SEP to calculate the band structure of graphene. The real-space structure of graphene can be described by a 2D unit cell with primitive lattice vectors z-axis) separately, the symmetry characteristics of the bands can be easily distinguished. Here, the even (odd) parity states are presented in green (red) color. It is noted that the red curves (with odd parity) are related to the In As shown in We consider a graphene nanoribbon with armchair edges with a width of ene. See b. Then, The Bloch states of the AGNRs superlattice can be written as linear combinations of basis functions that are products of 2D plane waves (labeled by wave vectors duced in ). For wiructures . If the Thus, we can write the Hamiltonian of the AGNR as y-axis. Thus, we can define symmetrized basis states with respect to the x-mirror as follows: In addition to the z-mirror symmetry, the AGNR also has x-mirror symmetry for any wave vector, i.e., The overlap matrix is given by the same expression above, with s-like) states with even and odd parity, respectively, under the x-mirror operation. Eigenstates of Here, we divide the basis set into four different subsets according to different symmetry types labeled by {The graphene bulk basis adopted above can describe the band folding due to the quantum confinement effect in the nanoribbon well, but it requires a large number of basis states to fully capture the effect of localized edge states. The AGNRs band structures obtained by solving Equation (43) are shown in We also performed DFT calculations of the same AGNR within the basis constructed by 2D plane waves multiplied by B-spline functions of z, as described in . The edgWe found that, as shown in The SEP band structures of the AGNR with the same relaxed atomic positions as determined by DFT but with the pseudopotential (PP) given by Equation (29) are shown in y-axis. As shown in To investigate the effect of local potential induced by the edge creation, we took the difference between the DFT (red curve) and SEP results (green curve) in z-dependence of the bond-charge contribution near the edges. We approximate the net three-dimensional local potential, including the bond-charge redistribution near the edges by a separable form:Finally, we add the edge-induced correction in the local pseudopotential, Here, After adding the correction term Many experimental studies on graphene and AGNR-related devices have been reported in the last decade ,59,60,61According to simple models that impose rigid boundary conditions on the edges of AGNRs, the band gap becomes zero when  integer ,62. Our mensions . The banculation  and alsoculation . Howeverculation . Since oculation , which pculation ,55,56,57culation . z-axis, our calculated band energies are absolute values with respect to the vacuum level. Therefore, it is meaningful to make such a comparison. For the case of 15-AGNR, the band gap obtained by the current SEPM is 0.49 eV, which is ~0.5 eV lower than the dI/dV measurements of 1.03 eV [For the case of 9-AGNR, the band gap obtained by the current SEPM is 0.68 eV, which is 0.7 eV lower than the 9-AGNR band gap measured by dI/dV measurements (~1.4 eV)  due to t 1.03 eV . For the 1.03 eV . Therefo results , which c results , in ordez-axis mirror), our SEP method can nearly reproduce all salient features of the DFT results with good accuracy. The time needed to compute the whole band structure associated with We developed a semi-empirical pseudopotential (SEP) method that is easy to implement and capable of obtaining accurate band structures for graphene and armchair-edged graphene nanoribbons. For the The SEP method with the same edge-induced correction potential given in Equation (51) is also applicable for AGNRs of sizes different from the example used here since the dimer formation on AGNR edges should not be significantly affected by the width of the interior region. Thus, the current model is suitable for modeling any size of AGNR  see b as a coThe close interplay between theoretical and experimental studies fosters a deeper understanding of AGNRs. Moreover, experimental data provide feedback to refine and improve theoretical methods. The collaboration between theorists and experimentalists allows for the identification of new phenomena and the validation of theoretical models. Together, theoretical and experimental studies offer a comprehensive perspective on AGNRs’ properties and pave the way for potential applications in nanoelectronics and beyond.


Whether pharmacokinetic (PK)/pharmacodynamic (PD) target attainment for meropenem measured in plasma is a clinically reliable surrogate for target attainment in the epithelial lining fluid (ELF) in pneumonia is unclear. The objective of the current study was to characterize target attainment in plasma and ELF using prospectively collected samples and to define predictors of optimal target attainment.vs. PK/PD goals of 100% T>1xMIC and 100% T>4xMIC for a susceptible MIC of 2 mg/L.Individual Bayesian meropenem plasma and ELF profiles were generated using Pmetrics for the first 24 hours of treatment. First 24-hr PK/PD target attainment was evaluated plasma, and VELF estimates were 6.2 L/hr, 45.7, and 28.3 L. For the 100% T>4xMIC goal the following target attainment groups were identified: optimal (≥95%) in plasma and ELF , near-optimal ( >50% and < 95%) in both plasma and ELF , suboptimal (< 50%) in ELF only , suboptimal (< 50%) in plasma only , and suboptimal (< 50%) in both ELF and plasma . Loading doses significantly improved the likelihood of optimal vs. suboptimal target attainment in ELF and plasma  but did not reliably discriminate other groups.Sixty-seven patients contributed ELF and plasma PK data (range: 1-3 samples/patient for each matrix). Mean population CL, VIndividual observed meropenem (ordinate) and model predicted meropenem (abscissa) concentrations in plasma (A) and ELF (B) in patients with pneumonia.Optimal target attainment was achieved in only 40% of patients while nearly 20% of patients had suboptimal attainment in both plasma and ELF. Use of plasma as a surrogate for ELF would miss up to 20% of patients with suboptimal ELF attainment, suggesting that therapeutic monitoring of ELF may be required in some patients to optimize PK/PD attainment.Marc H. Scheetz, PharmD, MSc, Abbvie: Advisor/Consultant|ASHP: Honoraria|Chambless, Higdon, Richardson, Katz & Griggs, LLP: Expert Testimony|Cidara: Advisor/Consultant|Entasis: Advisor/Consultant|F2G: Advisor/Consultant|GSK: Advisor/Consultant|Guidepoint Global: Honoraria|Hall, Booth, Smith, P.C.: Expert Testimony|Merck: Advisor/Consultant|Reminger Co., L.P.A: Expert Testimony|Spero: Advisor/Consultant|Takeda: Advisor/Consultant|Taylor, English, Duma, LLP: Expert Testimony|Third Pole Therapeutics: Advisor/Consultant Michael N. Neely, MD, Astellas Pharma Global Development, Inc.: Advisor/Consultant|Astellas Pharma Global Development, Inc.: Support for the present publication Richard G. Wunderink, MD, bioMerieux: Honoraria|Kariius: Clinical Evaluation Committee|LaJolla: Advisor/Consultant|Pfizer, Inc: Clinical Evaluation Committee|Shionogi: Advisor/Consultant Nathaniel J. Rhodes, PharmD MS, Third Pole Therapeutics: Advisor/Consultant


The catalytic effect of graphene on the corannulene bowl-to-bowl inversion is confirmed in this paper using a pair-wise dispersion interaction model. In particular, a continuum approach together with the Lennard-Jones potential are adopted to determine the interaction energy between corannulene and graphene. These results are consistent with previous quantum chemical studies, which showed that a graphene sheet reduces the barrier height for the bowl-to-bowl inversion in corannulene. However, the results presented here demonstrate, for the first time, that the catalytic activity of graphene can be reproduced using pair-wise dispersion interactions alone. This demonstrates the major role that pair-wise dispersion interactions play in the catalytic activity of graphene. The catalytic effect of graphene on the corannulene bowl-to-bowl inversion is confirmed in this paper using a pair-wise dispersion interaction model. Since van der Waals forces dominate the interaction between corannulene and graphene, this paper adopts the Lennard-Jones potential to determine the interaction energy between the two molecules. Here, we assume that carbon atoms on graphene are evenly distributed on its surface so we can use continuum surface approximation to model graphene. For corannulene, its three possible conformations are considered, which are concave-up bowl, concave-down bowl and flat circular structure. Two approaches to model corannulene–graphene interaction are used. The first approach considers corannulene as a collection of 30 discrete atoms (20 carbon and 10 hydrogen atoms), and so the total energy is obtained by summing 30 pairwise interaction energies between each atom on corannulene and a graphene sheet. In the second approach, due to its geometry, we model corannulene as a collection of four circular rings (three carbon rings and one hydrogen ring) centred on the same axis , and on In the following section, we give mathematical background for the two approaches to model corannulene–graphene interactions. Detailed calculation of the integrals involved are provided in Appendices A and B. Numerical results for the interaction energies are shown in Section 3 for the three conformations of corannulene. These results are also confirmed by molecular dynamics (MD) and density functional theory (DFT) simulations which their detailed set-ups are given in Appendices C and D, respectively. Finally, concluding remarks is provided at the end of Section 3.2ρij is the distance between atoms i and j, Aij and Bij are the attractive and repulsive constants, respectively. We note that Aij = 2εijσij6 and Bij = εijσij12 where  is the energy well depth and σij = (σi + σj)/2 is the van der Waals diameter. In this paper, the van der Waals parameters for carbon (C) and hydrogen (H) are taken from Rappe et al.25 where εC = 0.4393 kJ mol−1, σC = 3.8510 Å, εH = 0.1841 kJ mol−1 and σH = 2.8860 Å. Thus, the Lennard-Jones constants Aij and Bij can be evaluated as given in Due to its simple form, the Lennard-Jones potential is commonly employed to determine the interaction energy between two non-bonded atoms, which is given byi on the first molecule and atom j on the second molecule, which is given byρij is the distance between atoms i and j.In a fully discrete approach, the total interaction energy between two non-bonded molecules can be obtained by summing the pairwise potential energy ρ denotes the distance between typical surface elements dS1 and dS2 on the first and second molecules, respectively. The constants η1 and η2 are the mean surface atomic densities of the two molecules.Another method to model the interaction between two non-bonded molecules is known as a continuum approach. This approach assumes that atoms on each interacting molecule are uniformly distributed over its entire surface of the molecule. Thus, the double summation in 26The advantage of using η is the surface density of atoms on the regular shaped molecule, ρi is the distance between a typical surface element dS on the continuous molecule and atom i on the molecule which is modelled as discrete.In the interest of modelling an irregularly shaped molecule interacting with a regular shaped structure, an alternative hybrid discrete-continuum approach is introduced, which is given byxy-plane. For corannulene, we first assume a fully discrete structure with 30 atoms (10 hydrogen atoms (blue) and 20 carbon atoms (black)) as shown in In this paper, we use 2.115 Mathematically, we represent an atom on a corannulene as a typical point with coordinates  as shown p, q, 0). Since there are 20 carbon and 10 hydrogen atoms on the corannulene, using ρi is the vertical distance of atom i from graphene sheet, ηg is the atomic density of graphene sheet (ηg = 0.3812 Å−2) and In(ρ)  is defined byHere, we model a corannulene as a collection of 30 discrete atoms. The coordinates of a corannulene in all three conformations can be found from Karton.In(ρ) is given in Appendix A.We note that the derivation of 2.21 to R4 , whereas R2, R3, and R4 involve non-bonded atoms. These rings are chosen since they are co-planar in the equilibrium (bowl-shaped) and transition state (flat) structures of corannulene. Since the positions of atoms on a corannulene are as shown in o R4 see . We noteηj denotes the atomic density of the ring Rj, Aj = AC–C and Bj = BC–C when j = 1, 2 and 3 and Aj = AC–H and Bj = BC–H when j = 4. The integral Jn(ρ) (n = 3 and 6) is defined byρ in ρ is the distance from graphene sheet to ring R1 and the distances from graphene sheet to rings R2, R3 and R4 are given by ρ + δ1, ρ + δ1 + δ2 and ρ + δ1 + δ2 + δ3, respectively. Similarly, for a concave-down bowl ρ is measured from graphene sheet to the closet ring of corannulene, which is R4 in this case. The distances from graphene sheet to rings R3, R2 and R1 are given by ρ + δ3, ρ + δ3 + δ2 and ρ + δ3 + δ2 + δ1, respectively. Finally, for flat circular shaped corannulene, all rings are concentric and have the same vertical distance ρ from the graphene sheet.Mathematically, the problem reduces to finding the interaction energy between a ring and a graphene sheet as shown in In the next section, we plot the interaction energies for the three conformations of corannulene interacting with a graphene sheet. The results are also benchmarked with molecular dynamics simulations.3ρ which is the closest distance between corannulene and graphene sheet. We obtain identical results for both discrete and continuous ring approaches, which are plotted as solid lines in ρmin) for each conformation of corannulene that minimises the interaction energy of the system. The values of ρmin and the corresponding minimum energy are given in −1, whereas the interaction energy between the concave-up bowl and concave-down bowl and the graphene sheet amount to 129.7 kJ mol−1 and 167.3 kJ mol−1, respectively. Thus the pair-wise dispersion interactions between the planar graphene sheet and the planar transition structure are stronger by 48.9 and 11.3 kJ mol−1, respectively, than the concave-up and concave-down structures. This result is due to the closer proximity of the carbon atoms of corannulene and graphene in the planar transition structure than in the concave-up and concave-down structures.Here, the interaction energy is determined as a function of 15,17 In order to compare on an even keel between the interaction energies obtained using our pair-wise dispersion model we need to calculate the DFT interaction energies on the electronic potential energy surface. For this purpose, we performed DFT calculations on the electronic potential energy surface using the PW6B95-D4 functional (see Appendix D for further details). At the PW6B95-D4/def2-TZVPP level of theory with basis set superposition error (BSSE) corrections, we obtain the following interaction energies between corannulene and graphene 82.6 (concave-up bowl), 111.3 (planar TS), and 87.1 (concave-down bowl) kJ mol−1. Using a larger quadruple-ζ basis set without BSSE corrections, namely at the PW6B95-D4/def2-QZVPP level of theory, we obtain similar interaction energies of 87.1 (concave-up bowl), 117.1 (planar TS), and 91.6 (concave-down bowl) kJ mol−1. There is little to choose between the two levels of theory since both have different advantages and disadvantages in terms of basis-set completeness. However, the differences of 4.4–5.8 kJ mol−1 between both sets of results indicate that we are only a few kJ mol−1 away from the complete basis set limit. Here, we will focus on the results obtained with the larger def2-QZVPP basis set. The pair-wise dispersion model predicts much larger interaction energies of 129.7 (concave-up bowl), 178.6 (planar TS), and 167.3 (concave-down bowl) kJ mol−1  as a location of an atom on corannulene interacting with a graphene sheet lying on the xy-plane on which its typical point has coordinates . To determine the interaction energy between a single atom and a graphene sheet using the Lennard-Jones potential, we introduce the integral In(ρ) which is given asS is the surface element of graphene sheet and d is a typical distance between atom on the corannulene and graphene sheet  so that Next, we substitute consequently, SinceM = ρ tan ψ where ψ ∈ , we obtainwhich yieldand upon simplifying gives By further substituting r with typical point  interacting with a graphene sheet lying on the xy-plane on which its typical point has coordinates . To determine the interaction energy between a ring and a graphene sheet using the Lennard-Jones potential, we introduce the integral Jn(ρ) which is defined byS is the surface element of graphene and d is the distance between typical points on the ring and graphene sheet  software packageζ def2-nZVPP basis sets .28,29 Where the recently developed, atomic-charge dependent D4 dispersion correction is employed.30,31 The PW6B95 exchange-correlation functional has been extensively benchmarked and found to be robust for both reaction energies and barrier heights involving related systems.18,20,32–38 We were able to perform basis set superposition error (BSSE) calculations in conjunction with the def2-TZVPP basis set.39–41 However, the BSSE calculations in conjunction with the def2-QZVPP basis set proved beyond our computational resources. All optimized geometries were taken from ref. 42Density functional theory (DFT) calculations were performed using the hybrid meta-GGA  DFT method PW6B95-D4 in conjunction with the triple- and quadruple-There are no conflicts of interest to declare.


Sarcoidosis is an inflammatory and granulomatous disease of uncertain etiology that can impact various organ systems and exhibits diverse clinical presentations, which adds to the complexity of disease diagnosis and management. Pathologically, it is distinguished by the presence of noncaseating granulomas within the affected organ system. In this case report, we describe a 34-year-old Caucasian female patient with isolated splenic and possible hepatic involvement of sarcoidosis, presenting with severe abdominal pain. The absence of the typical pulmonary, cutaneous, or joint involvement posed challenges in achieving a definitive diagnosis and determining the appropriate management. Imaging studies revealed hepatic and splenic hypodensities, necessitating consideration of various differential diagnoses, including lymphoproliferative disorders, immunological disorders, environmental particle exposure, infectious causes, neoplasms, and drug reactions. The severity of symptoms in this case required hospital admission for pain and nausea control, biopsy, and eventual splenectomy with pathology that confirmed the diagnosis of splenic sarcoidosis. Sarcoidosis, a multisystem inflammatory disease, was initially identified and named over a century ago. In 1878, Sir Jonathan Hutchinson first described the condition of sarcoidosis . While iThis article was previously presented as an abstract at the 2023 WV Society of Hospital Medicine Abstract Competition in May 2023.Cytomegalovirus, Human immunodeficiency virus, Epstein-Barr virus, hepatitis panel, acid-fast bacilli, Bartonella, Chlamydia trachomatis, Chlamydia psittaci, Treponema pallidum, enteric bacteria profile, Lyme disease, Coxiella, Cryptococcus, Histoplasma capsulatum, Blastomyces dermatitidis, ova and parasites, and Toxoplasma gondii. Additionally, an autoimmune workup was conducted, involving testing for systemic lupus erythematosus, mixed connective tissue diseases, Sjogren's syndrome, scleroderma, polymyositis, alpha-1 antitrypsin, and ceruloplasmin. The comprehensive workup yielded unremarkable results, except for an elevated C-reactive protein level of 4.2 mg/dL (reference range <0.9 mg/dL). Additional imaging studies, including CT of the chest and CT of the head, did not reveal any significant findings. The patient received symptomatic management and was referred to a tertiary care facility for further workup, which was also unrevealing. Despite extensive workup and symptomatic management, she continued to have persistent abdominal pain. She was then admitted to the hospital, where a repeat liver biopsy was performed via endoscopic ultrasound, this was inconclusive with some rare noncaseating granulomas. Universal PCR analysis was repeated, and the results were negative for fungal DNA or mycobacterium DNA. Sarcoidosis was suspected, prompting initial treatment with a prednisone taper. However, the patient did not tolerate the steroids, due to significant anxiety, agitation, and other adverse side effects. Although antibiotics were tried based on infectious disease recommendations, no definitive diagnosis had been made at that time, and this failed to provide relief for the patient. Consequently, the patient opted for splenectomy, and the subsequent pathology report confirmed the suspected diagnosis of sarcoidosis . Contrast-enhanced abdominal and pelvic computed tomography (CT) displayed multiple low-attenuation lesions in the liver and spleen Figure . A liverDue to its intricate characteristics, the potential for multiorgan involvement, and the absence of pathognomonic features, sarcoidosis is primarily considered a diagnosis of exclusion. The diverse range of clinical presentations associated with sarcoidosis can present challenges in both diagnosing and managing the disease. While sarcoidosis was suspected in this case, the involvement of splenic and hepatic lesions with an inconclusive biopsy necessitated a comprehensive differential diagnosis, encompassing lymphoproliferative disorders, immunological disorders, environmental particles exposure, infectious causes, neoplasms, and drug reactions . ExtrapuIsolated splenic sarcoidosis represents a rare manifestation of sarcoidosis, which poses challenges in terms of diagnosis due to the absence of a definitive diagnostic test. Instead, the diagnosis relies on the presence of clinical and radiographic manifestations consistent with sarcoidosis, exclusion of other diseases, and histopathologic identification of noncaseating granulomas. The treatment of sarcoidosis often involves the administration of steroids; however, in this specific instance, the patient exhibited poor tolerance, thereby requiring alternative therapeutic approaches. Improving care for patients with sarcoidosis often requires multidisciplinary teams working together to understand the unique patient presentation and affected organ system, to maximize the diagnosis and treatment for the safety and quality of life of the patient.


The design and development process of wind velocity sensors for mining has been a challenging task due to the complexity of a large number of field tests. To resolve this problem, this study aimed to provide a comprehensive test device for the design and development of high-precision wind velocities sensor for mining. Through a combination of experiments and computational fluid dynamics (CFD), a device that can simulate the mine roadway environment was developed. The device can control the temperature, humidity, and wind velocity parameters to fully replicate the mine roadway environment. It gives designers and developers of high-precision wind velocity sensors for mining a rational and scientific testing environment. In order to quantitatively define the uniformity of air flow in the mine highway section, the research introduced the non-uniformity determination method. The approach was expanded to assess the cross-sectional uniformity of temperature and humidity. The wind velocity within the machine can increase to 8.5 m/s by selecting the right kind of fan. The minimum wind velocity non-uniformity at this moment is 2.30%. The device’s internal temperature can be raised to 38.23 °C and its humidity level can be increased to 95.09% by carefully crafting the rectifier orifice plate’s structure. At this time, the lowest temperature non-uniformity is 2.22%, and the lowest humidity non-uniformity is 2.40%. The device’s average wind velocity is 4.37 m/s, its average temperature is 37.7 °C, as well as its average humidity is 95%, per the emulate results. The device’s non-uniformity in wind velocity, temperature, and humidity is 2.89%, 1.34%, and 2.23%, respectively. It is capable of simulating the mine roadway environment in its entirety. The ventilation system is the fundamental system to ensure the safety of mine production. According to statistics, many accidents are caused by ventilation system breakdowns that seem to go unnoticed in time . It is cCreating the mimicking test equipment is premised on mastering the mine roadway’s environmental parameters. The wind velocity, temperature, and humidity parameters of mine roadway air flow have already been tested and simulated by many scholars. They believe that the wind current in the mine roadway is basically distributed in parallel streamlines and that the wind velocity is distributed evenly in the same vertical section . The tunBased on the findings of the aforementioned investigation combined with the environmental parameters of the mine roadway measured data, the wind velocity, temperature, and humidity coupling device model was designed and constructed for this investigation using the CFD approach. For a complete simulation of the tunnel environment, it can control the wind velocity, temperature, and humidity parameters simultaneously. In a bid to quantitatively determine the uniformity of wind flow in the mine roadway section, the study applies the non-uniformity determination method . The appThe device’s three-dimensional model was created using AutoCAD software and can be seen in 1 = 620 mm, length L1 = 400 mm, impeller diameter D = 600 mm; the diameter of humidification pipe section D2 = 50 mm, length L2 = 100 mm; the length of the heating pipe section L3 = 200 mm, and the diameter was adjusted according to the rectifier effect of the rectifier orifice. The test pipe sections were square pipes with side length a = 500 mm and length L4 = 1000 mm. The origin of the device coordinate was located at the center of the test pipe section near the rectifier orifice plate. yOz plane; monitoring surface A was located at x = 0, while monitoring surface B was located at x = 1000.The specific dimensions of the device were: fan diameter DSST k-ω Turbulence model, the internal flow field and heat transfer of the device model met the following equations:Fluent, as a leading CFD software with a wide audience, was used to solve the model calculation of this study. The simulation process adopted double precision three-dimensional solver and The mass conservation equation isThe momentum conservation equation isThe energy conservation equation isu, v and w—components of fluid velocity in x, y and z directions, respectively, m/s;P—pressure, Pa;μ—dynamic viscosity, Pa·s;T—temperature, K;pC—specific heat capacity at constant pressure, J/(kg·K);λ—thermal conductivity, W/(m·K).SST k-ω. For turbulence model, the energy equation was opened, and the convergence condition was that each residual error was less than 10−6. In the process of simulation, such assumptions were made: ① The air flow can flow uniformly at the inlet and outlet of the model, and the physical parameters will not change; ② the fluid is fully developed in the simulation process; ③ viscous dissipation between fluids is considered; ④ the fluid is incompressible Newtonian fluid; ⑤ ignore gravity effects.Meshing was used to mesh the above three-dimensional model, and the mesh independence was verified. The rotating part of the axial flow fan was treated with sliding mesh. The rotating velocity of the axial flow fan was 1450 r/min according to the actual operating parameters of the fan. The ambient temperature was 25 °C and the humidity was 40%. The air flow was not heated and humidified, the hole diameter of the rectifier orifice plate was 40 mm, and the hole arrangement was straight. Turbulence model using The distribution of wind velocity, temperature, and humidity in the middle section of the mine roadway was basically uniform. Therefore, this paper introduced the non-uniformity judgment method to quantify the simulation and experimental results by calculating the non-uniformity of wind velocity, temperature, and humidity. Taking the wind velocity non-uniformity as an example, the wind velocity non-uniformity can quantitatively describe the flow field distribution at the test section of the device. The formula for calculating the wind velocity non-uniformity is shown in Equation (4). The calculation formula of the temperature and humidity non-uniformity refers to the calculation formula of the wind velocity non-uniformity.When the non-uniformity does not exceed 25%, it can be considered that the flow field inside the device is uniform. Therefore, the non-uniformity of wind velocity, temperature, and humidity of the device shall be less than 25%. Furthermore, the measuring points were located on monitoring surfaces A and B, and took 16 uniformly distributed measuring points, respectively.Q is where, in ideal conditions:The mine roadway’s main inlet and return air velocities must not exceed 8 m/s in accordance with mine safety regulations. Therefore, the device’s wind velocity must not be less than 8 m/s when the inlet fan is operating. The test pipe section has a side length of 500 mm square pipe. The air volume calculation formula says that the required air volume Q—air volume, m3/h;S—sectional area of air duct, m2;v—wind velocity, m/s.Under ideal circumstances, it is necessary to use the safety factor to adjust the air volume so that the fan has a sufficient supply of air. The safety factor, which is used frequently in fan selection and air volume design, is an increase of five to twenty percent based on the ideal air volume. The value of the safety factor should not be too high in order to cut down on the amount of money spent on equipment and running it. The safety factor of 1.15 was used in this paper to calculate the corrected air supply, which was:3/h;Q—ideal air supply, m3/h;3/h. However, the simulation analysis revealed that the wind velocity was only 6.5 m/s after employing the type A axial flow fan. This is mostly because of the fluid’s general viscosity, the loss of vortex caused by boundary layer separation, and the loss of friction between the internal components of the fan and the air flow. Additionally, there will be some space between the fan’s static components and its rotating parts. The fan will develop a high-pressure and a low-pressure region as the impeller rotates. Leakage loss will result as a result of the air flowing through these gaps from the high pressure region to the low pressure region. The test device also has a rectifier orifice plate, a humidifying pipe section, and a heating pipe section, all of which make the air resistance when passing through the device too high and prevent the wind velocity from reaching 8 m/s.The corrected air supply volume will be used to select the fan. The type A axial flow fan can theoretically satisfy the demand for air with a volume of 10,000 m3/h. As depicted in According to the simulation analysis, the pipeline’s air velocity requirements call for an type B axial flow fan with a volume of 21,500 mThe selection of a fan may be sufficient to provide the device with sufficient wind velocity; however, it is necessary to investigate the distribution of the test device’s temperature and humidity. Miners’ primary location for carrying out production tasks is the stope. In the stope, it is necessary to measure the temperature, humidity, and wind velocity. As a result, the simulating test device must be able to completely replicate the parameters of the stope environment. The mine safety regulations stipulate that the wind velocity in the stope shall not exceed 4 m/s and the wet-bulb temperature shall not exceed 30 °C. The environment in the downhole is humid, frequently exceeding 90%. To ensure that the mine stope’s environmental parameters can be replicated, the device needs to be able to achieve a heating temperature above 35 °C and a humidity above 95% at a wind velocity of 4 m/s.This method effectively avoids the non-uniform distribution of air flow caused by the phenomenon of cylindrical flow around the cylinder heating tube , due to Utilizing the breeze velocity, temperature, and mugginess non-uniformity as the assessment file, the impact of various designs of the rectifier hole plates on the lopsidedness were examined. The outcomes show that when the (f) structure with roundabout game plan, focus gap of 60 mm, corner opening of 60 mm, and other gap of 40 mm is embraced, the temperature and mugginess inside the test gadget are equally circulated. Obtained by reading section data:Based on the analysis of 2, and the flow rate of the water mist generator was 1.8 m/s. In addition, wind velocity sensors, temperature sensors, and humidity sensors were used for real-time monitoring of environmental parameters inside the device. In order to ensure that the temperature and humidity sensors could work normally in the simulated high temperature and humidity environment, the epitaxial waterproof highly sensitive temperature and humidity probe was selected. This probe can work stably at the temperature of 20~50 °C and the humidity of 20~100%. There were two sets of wind velocity, temperature and humidity sensors, which were located in the center of the two monitoring pipe sections (monitoring surface A and B). The arrangement of the device and sensors are shown in According to the results of fan selection and rectifier orifice plate optimization, a simulation testing device of mine roadway with adjustable wind velocity, temperature. And humidity was constructed. The model was based on the similarity theory ,21, and The device is tested after the device runs stably , and recAs can be seen from In this study, CFD technology was combined with an experimental design. We designed and constructed a mine roadway simulating test device with adjustable wind velocity, temperature, and humidity. The device could simultaneously control wind velocity, temperature, and humidity parameters to fully simulate the tunnel environment. The results were as follows:3/h was used in the test device. The wind velocity inside the device could reach 8.5 m/s. At this time, the minimum wind velocity non-uniformity was 2.30%.(1) Through air volume calculation and simulation analysis, it was concluded that axial flow fan with air supply of 21,500 m(2) By changing the arrangement of the rectifier orifice plate, center aperture, corner aperture, and other parameters, the structure of the rectifier orifice plate was optimized. It is concluded that when the pore arrangement mode of the rectifier orifice plate was circular arrangement, the center aperture was 60 mm, the corner aperture was 60 mm, and the other aperture was 40 mm, the wind velocity inside the device could reach 4.83 m/s, the temperature could reach 38.23 °C, and the humidity could reach 95.09%. In addition, the distribution of wind velocity, temperature, and humidity in the device was relatively uniform. The lowest non-uniformity of wind velocity was 14.17%, the lowest non-uniformity of temperature was 2.22% and the lowest non-uniformity of humidity was 2.40%.(3) According to the results of fan selection and rectifier orifice plate optimization, a simulation testing device of mine roadway with adjustable wind velocity, temperature, and humidity was constructed. The average wind velocity of the device was 4.37 m/s, and the lowest wind velocity non-uniformity was 2.89%. The average temperature was 37.7 °C, and the lowest temperature non-uniformity was 1.34%. The average humidity was 95% and the lowest humidity non-uniformity was 2.23%.The research results showed that the device can fully simulate and reproduce the wind velocity, temperature, and humidity environment of the mine roadway. It can provide a scientific and reasonable test platform for the design and development of high-precision wind velocity sensor. It is a fundamental device for improving the wind velocity monitoring technology in the mine roadway and plays an important role in ensuring the safe production of the mine.


Highly thermally conductive composite films with elimination of graphene nanosheet wrinkles prepared by a constrained drying strategy of in-plane stretching.Reveals the mechanism of graphene nanosheet wrinkle elimination to improve the thermal conductivity of composite films and demonstrates its use as a heat sink film for cooling flexible LED chips and smartphones.The online version contains supplementary material available at 10.1007/s40820-023-01252-w. π–π interactions. The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets, thereby creating a fast in-plane heat transfer channel. The composite films (GNS/ANF-60 wt%) with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity (146 W m−1 K−1) and tensile strength (207 MPa). The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones, showing promising applications in the thermal management of high-power electronic devices.Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices. However, when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites, capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying, which greatly reduces the thermal conductivity of the composites. Herein, graphene nanosheets/aramid nanofiber (GNS/ANF) composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds and The online version contains supplementary material available at 10.1007/s40820-023-01252-w. The continuing miniaturization and high integration of microelectronic components has brought the issue of heat dissipation into sharper focus , 2. For Graphene displays an ultra-high in-plane thermal conductivity, due to its perfect two-dimensional structure , 21. Its−1 K−1, and the tensile strength increased from 99 to 207 MPa  During in-plane stretching, the mechanical tension not only counteracts the contraction effect of the capillary force, but also spreads and flattens the flexible large-size graphene nanosheets along the in-plane direction. This process eliminates the wrinkles of graphene nanosheets, as well as the air bubbles introduced by the wrinkles, making the structure of GNS/ANF composite films more compact. The oriented and ordered stacking of GNS is favorable for the rapid phonon transfer along the plane. (ii) There is a strongHigh-quality graphene nanosheets  were purchased from Deyang Carbenene Technology Co., Ltd. AMF (Kevlar 29) was purchased from Dongguan SOVETL Co., Ltd. Potassium tert-butoxide was provided from Sigma-Aldrich, and dimethyl sulfoxide  was used as received.Constrained dried GNS/ANF films were prepared by in-plane stretching of GNS/ANF composite hydrogels. Six grams of AMF and 4.5 g potassium tert-butanol were added to 189.5 g dimethyl sulfoxide, and the mixture was mechanically stirred for 12 h to obtain dark red, viscous ANF solution (3 wt%). GNS (0.75 g) was added to dimethyl sulfoxide solution (32.58 g) and dispersed by sonication for 2 h . Then, 3 wt% ANF solution (16.67 g) was added and mechanical stirring was continued for 12 h to form uniformly dispersed GNS/ANF-60 wt% sol. The GNS/ANF sol was poured into a Petri dish and then immersed in water to form a black GNS/ANF hydrogel, which was rinsed with repeatedly using deionized water to completely remove dimethyl sulfoxide and potassium tert-butanol. The mass fraction of GNS in the composite hydrogel was 1.5 wt% and the mass fraction of ANF was 1 wt%. The GNS/ANF hydrogels were stretched in-plane with a stretching device and kept under stretching constraint until drying, as shown in Fig. 2. Raman spectra were recorded by microscopic confocal Raman spectrometer (ARAMIS HORIBA) with an excitation wavelength of 532 nm. XPS data were obtained using an X-ray photoelectron spectrometer . FTIR spectra were collected using a Nicolet IS50 FTIR spectrometer (Thermo Fisher Scientific). X-ray diffraction (XRD) patterns were obtained using a LabX XRD-6000 (SHIMADZU) instrument with Cu Kα radiation at a scanning speed of 10° min−1. Tensile properties were measured on a Shimadzu AGS-X Tester. The thermal conductivity of the nanocomposite was calculated with K, α, Cp represent thermal conductivity, thermal diffusivity, density, and heat capacity, respectively. Thermal diffusivity was measured using the laser flash method . Density was obtained by the calculation of sample volume and weight. The specific heat capacity was obtained by differential scanning calorimetry . Infrared thermal images were taken with an infrared thermal imager (FOTRIC 345). The electrical conductivity was analyzed by four-probe method . Thermogravimetric analysis (TGA) was performed with a simultaneous thermal analyzer  at a heating rate of 10 °C min−1 under air atmosphere.SEM images were obtained with a field-emission scanning electron microscope . TEM images were obtained with a transmission electron microscope . AFM images were obtained with an atomic force microscope . The test area of Fig. ID/IG = 0.07, C/O = 47.1, Fig. S1) were utilized in this study. It is worth noting that graphene nanosheets have numerous edge folds and wrinkles, which will make it difficult to achieve an orderly alignment of graphene nanosheets in composites . These results demonstrate that the in-plane stretching effectively improves the stacking orientation of graphene nanosheets and increases the tensile strength of the composite films. Interestingly, the electrical conductivity of the composite films gradually increased with the increase of the in-plane stretching ratio, indicating that graphene nanosheets with wrinkles eliminated by in-plane stretching build better conductive paths .−1 is increasingly shifted to the left toward 1605 cm−1, indicating that the π–π interaction between GNS and ANF becomes stronger. To further confirm this strengthening of the π–π interaction, we examined the XPS spectra of C 1 s. As the in-plane stretching ratio increased, the peak representing the π–π interaction gradually shifted from 290 to 290.8 eV, consistent with the Raman spectroscopy results  [−1 (C=O stretching vibration) and 3326 cm−1 (N–H stretching vibration) were observed to broaden and shift to the left  . Meanwhieft Fig. e, f, indAfter in-plane stretching, the GNS is stretched out to eliminate the folds, resulting in a tighter bond with ANF, resulting in stronger interfacial interactions. In addition, the GNS is expanded and tiled along the in-plane direction to eliminate air bubbles contained within the wrinkles. The alternate stacking of GNS and ANF in an orderly orientation forms a more compact and orderly structure, and the density of the composite films gradually increases Fig. g. All thThe excellent thermal conductivity and mechanical properties of the GNS/ANF composite films with eliminated GNS wrinkles have been demonstrated, and its application as a thermal management material for cooling flexible LED chips and smartphones will now be discussed. As shown in Fig. In addition, these films were also integrated into the internal back of the smartphone Fig. e, f, and−1 K−1), high tensile strength (207 MPa) GNS/ANF-60 wt% composite films were prepared based on the in-plane stretching strategy and sol–gel-film transformation approach. The remarkable improvement in thermal conductivity is attributed to the in-plane stretching strategy, which effectively eliminates the graphene nanosheets wrinkles, improves the orientation of GNS along the in-plane direction, and further enhances the interfacial interaction between GNS and ANF. We believe that the GNS/ANF composite films with such exceptional thermal conductivity and mechanical properties hold promising applications for various thermal management applications in the electronics and automotive industries.In summary, ultra-high in-plane thermal conductivity (146 W mSupplementary file1 (PDF 1352 KB)Below is the link to the electronic supplementary material.