This article presents an overview of twisted bilayer graphene (tBLG) on their fabrication techniques and twisting angle-dependent properties.The properties of tBLG can be controlled by controlling the twisting angle between two graphene sheets. Two-dimensional (2D) materials exhibit enhanced physical, chemical, electronic, and optical properties when compared to those of bulk materials. Graphene demands significant attention due to its superior physical and electronic characteristics among different types of 2D materials. The bilayer graphene is fabricated by the stacking of the two monolayers of graphene. The twisted bilayer graphene (tBLG) superlattice is formed when these layers are twisted at a small angle. The presence of disorders and interlayer interactions in tBLG enhances several characteristics, including the optical and electrical properties. The studies on twisted bilayer graphene have been exciting and challenging thus far, especially after superconductivity was reported in tBLG at the magic angle. This article reviews the current progress in the fabrication techniques of twisted bilayer graphene and its twisting angle-dependent properties. It has attracted abundant interest after its first isolation was achieved through the micromechanical cleavage of graphite in 2004 [Graphene is composed of a one-atom-thick  in 2004 –4. It ha in 2004 –9. Howev in 2004 , their m in 2004 –16. The  in 2004 –19. The  in 2004 , 20, 21. in 2004 –27.θ) [θ = 1.05°) [Tc) ~ 1 K is comparatively high [Twisted bilayer graphene (tBLG) is fabricated by the stacking of two monolayers of graphene with a specific twisting angle (θ) ; in thisθ) , 29. Recθ) –33 and eθ) , which wθ) , 39–41. θ) , 28. Thiθ) . The Fer= 1.05°) ; howeverely high . Meanwhiely high –65. In t2/Si substrates via a simple wet-chemistry method [2/Si in the same way. The prepared sample is baked in the air at 150 °C for 20 min for enhancing the adhesion between the SLG substrate and SLG–SLG [In this section, we reviewed some of the recent advanced synthesis methods used to fabricate twisted graphene sheets. The twisted graphene layers are formed on the surface of crystalline graphite naturally due to the accidental folding of graphene layers onto other graphene flakes or themselves , 67. Sevy method –78, withy method . The twi SLG–SLG . In this2 substrate using a femtosecond laser and was divided into two pieces with a pair of parallel and straight cutting lines, as represented in Fig. θ and were accurately stacked together onto to Si/SiO2 substrate using a suitable transfer method. The control over the twisting angle of tBLG fabricated by this method is better than the other preparation methods.In another report, Kim et al.  reported2/Si substrate to make hydrophilic and hydrophobic sections with a distinct border, (2) the controlled SLG/PMMA delamination from the hydrophilic section in water, and (3) removal of the PMMA layer. The controlled folding in this procedure allows for the fabrication of tBLG structure with distinct stacking orientations; the required twisting angle was achieved by varying the hydrophilic and hydrophobic boundary folding angles. In a recent report, Cao et al. [Wang et al.  preparedo et al.  fabricatθ), as compared to the other [G band resonance and optical absorption and improves the chemical reactivity of tBLG [The variation in the graphene properties is produced due to the mode of stacking orientation among the two graphene layers and the number of stacked graphene layers , 84. Thehe other . The schhe other . The Dirhe other –89. The he other , causinghe other –93, whic of tBLG . The ban of tBLG , confirm of tBLG  by using of tBLG . The moi of tBLG . The sim of tBLG . The tBL of tBLG , 103.FigC) vibration modes and in-plane G and 2D vibration modes. The first-order Raman endorsed peak in graphene is a G band observed at ~ 1584 cm−1, accomplishing momentum conservation, which commands that the scattered phonon must carry no momentum. The D and D′ bands are originated from the intervalley and intravalley double-resonance Raman scattering mechanisms, respectively [R and R′ modes, which are from the TO and LO phonon branches, respectively [θ-dependent q wave vector, which triggers phonons inside of the Brillouin zone, due to which the layer breathing vibrations (ZO′ phonons) can be studied in a first-order light scattering [Raman spectroscopy plays a crucial role in the nondestructive analysis of the lattice structure, as well as the optical, electronic, and phonon properties of graphene , 105. Raectively –110. Twoectively –113, canattering . Lui et attering .−1 Raman shifts and observed two modes in a smaller range of twist angle. Figure G Raman peak intensity is intensely enhanced as a function of twisting angle, which illustrates that these G Raman modes and the lower-energy modes share the equivalent resonance amplification mechanism. The intensity of the enhanced G peak and the 2D band displays a maximum blueshift than the SLG at 12° twisting angle   [−1 are activated by the formation of moiré pattern [L is observed at ~ 94 cm−1. The intensities of (ZO′)L frequency mode, and the background covering on which the lower-energy Raman lines are comprised, demonstrate substantial resonance enrichment near the 12° twisting angle; it is associated with the G Raman peak enhancement. Another Raman mode observed at ~ 52 cm−1 is ascribed to the twisting mode due to the rotation between the two graphene layers with respect to each other. The advancement of the frequency and FWHM of the ZO′ mode as a function of L normalized I2D are shown in Fig. L mode frequency increases with the I2D when the twisting angle is less than the critical angle, and the frequency becomes nearly constant, when the twisting angle is greater than the critical angle. This illustrates that the intense variations in the FWHM and frequency of the (ZO′)L mode occurred when the twisting angle is close to the critical angle (12°). The low-frequency phonon dispersion shown in Fig. −1, and the phonon wave vector kL(ZO′) are in good arrangement with the ZO′ phonon dispersion in tBLG and confirming the obligation of this mode with the layer breathing mode (ZO′)L. The Raman study reveals that the fundamental properties of tBLG are different from the Bernal-stacked bilayer graphene.For investigating the twisting angle effects in tBLG, He et al.  carried le) Fig. a. The phngle (θ) , 117. Th pattern , 117. Th2 substrate which is shown in Fig. G band intensity increases for the ~ 12° twisting angle, attributable to distinctiveness in the joint density of states (JDOS) of tBLG, and its energy is entirely depending on the twisting angle, and the strength of optical transition is directed by the interlayer interactions, which allow direct optical imaging of these parameters, as shown in Fig. G band images of the similar tBLG domain at different excitation energies and the plot of Eex versus θpeak are shown in Fig. The Raman imaging reveals the differences in interlayer interactions, which is useful for the investigation of external physical, chemical, and optical properties of bilayer graphene. The white light dissimilarity enhances the reflection image of single and bilayer graphene on SiOθ = 0.01° to 0.2°) is found in the lower-energy range. The transition developments for the tBLG structures with θ = 10° are shown in the inset of Fig. σ1(ω) spectra of tBLG with different twisting angles show two separate interband transitions  the major absorption peak α originates from the transitions vHs2 → BE1 and BE2 → vHs1 [α-peak toward the higher energy as the twisting angle increases [σLB into two edges with various energies reveals that the Dirac cones of the bottom and top layers are transferred by varying the total energy [α show variation with the gate bias, as the interlayer potential irregularity breakdowns the configuration of the band edge and vHs. The VG-driven variation of σ1(ω) for the hole doping region is shown in Fig. σLB in Fig. α-peak toward lower energy, whereas its intensity is decreased noticeably, which confirms the changing of the band structure of tBLG with the gating. The optical absorption spectra showed notable variations like the shifting of inter-van Hove singularity transition peak and the splitting of interlinear band absorption, as well as the appearance of an extremely strong intra-valence band transition.The decreasing in the twisting angle interference among the two lattice periods creates a moiré pattern with a higher wavelength, where the properties of tBLG such as van Hove singularity and bandgaps seem to be present in the far-infrared region and the band velocity of the Dirac cone is considerably decreased , 119–122ons Fig. b: (1) Th2 → vHs1 , 129. Inl energy . The ints- and p-polarized lights with consequent laser wavelength consistent with the absorption enhancement, as shown in Fig. The PL excitation spectrum recorded after 2-photon excitation, also the twisting angle-associated tunable linear absorption spectrum, is shown in Fig. 2/Si substrate embedded with two terminals are shown in Fig. G band of 13° twisted tBLG domain showed a consistent 20-fold enrichment compared with the 7° twisted tBLG domain, as shown in Fig. Recently, Yin et al.  reportedσ) of the tMLG device in the 90 K to 273 K temperature range is shown in Fig. The perfect and superior characteristics of the bilayer graphene in twisted multilayer graphene (tMLG) than the suspended form of graphene could be attributed to the fact that the tMLG is tens of nanometer in thickness and maintains the graphene layers ultra-clean, as well as free from any substrate influence. These extraordinary properties in tMLG generate from the higher degree of decoupling that occurs from the angular twisting between the layers . RecentlThe interlayer contact conductance among the BLG with different twisting and stacking structures synthesized by the CVD method is recently discussed by Yu et al. . A statiρ) of the tBLG domain (θ = 1.06°) measured near the flat band condition for carrier densities spanning the lower-energy band is shown in Fig. ns/4 and superconducting states at different partial band fillings are revealed in Fig. ρ(T)) increases with the increase in temperature and remains steady with the metallic behavior. The resistivity (ρ(T)) measured in tBLG devices with different twisting angles near − ns/2 is shown in Fig. TH; the resistivity scales linearly with temperature below the temperature TH. At the lowest temperatures, resistivity diverges from a linear dependence on temperature. The tBLG devices clearly show the resistivity saturation, superconducting, or insulating behavior at moderate temperature regimes. The observed three distinctive temperature regimes are noticeable by the different behavior of resistivity (ρ(T)) depending on the carrier density and twisting angle.Polshyn et al.  discusseK or K′ wave vectors for the two graphene monolayers , as a function of temperature (T(K)) for two tBLG devices with 1.16° and 1.05° twisting angles, demonstrated zero resistance at 70 mK revealing the superconducting state  determined using a resistance of 50% of the non-superconducting state value was about 1.7 and 0.5 K for the two tBLG devices. The two-probe conductance versus carrier density at zero magnetic fields and a 0.4 T perpendicular magnetic field of M1 device is shown in Fig. n = 0). It also shows the states of insulating at the superlattice bandgaps n = ± ns. The insulating state at ± 3.2 × 1012 cm−2 is as a result of the presence of single-particle bandgaps in a band structure, as well as the observed conductance minima connected with many body gaps [12 to − 1.9 × 1012 cm−2 electrons per unit cell, the conductance was significantly high for nil magnetic fields than in the vertical 0.4 T magnetic field (B⊥), which reveals the presence of superconductivity at the magic angle. The density-dependent resistance of the tBLG device with a 1.14° twisting angle plotted almost over the complete flat band density range is shown in Fig. δn < 2 × 1010 cm−2), and at the magic angle (θ = ~ 1.1), the resultant hybridization and moiré superlattice among the graphene layers caused the development of a remote flat band at the charge neutrality point (CNP) [ns/2 and +3 ns/4. The superconductivity regions emerge in both electron- and hole-doped regions at ~ 10 mK base temperature with the dropping of resistance to zero. However, for ± ns/2 densities, below the base temperature, no sign of superconductivity is observed. The superconductivity appears considerably absent or weak on the lower-density side and extra stronger in the higher-density side of the insulator in both bands.The unusual superconducting behavior of different materials has been studied broadly for the last decades. The weak interlayer interaction creates the interlayer coupling in tBLG, and the strength of interlayer coupling as well as twisting angles equally affects the Fermi velocity and the VHSs of tBLG, which makes the novel electronic state of tBLG, which is different from those in SLG –140. Theers Fig. b. The inate Fig. c. The crody gaps . At 70 mnt (CNP) , 143. Inθ = 1.1 ± 0.1°) [B) and longitudinal resistance (Rxx) versus an elongated gate voltage (Vg) range at a 1.7 K temperature (Landau fan pattern) are shown in Fig. Vg = ± 0.85 V, as the lower-energy moiré bands are filling at densities nm = ± 4 (where nm is the number of charges per moiré unit cell) [Vg = 0.43 V from which an alongside set of Landau levels emanate. The peak on the half-filling and the twofold degeneracy of Landau levels illustrate the breaking of the symmetry of spin valley [nm = 0, ± 4, and +2, the resistance peaks are clearly observed in Rxx(Vg) at B = 0 and for different temperatures (0.28 to 5.2 K)  decreases, ρ decreases to zero with the two consecutive steep successions at T ~ 0.3 K and T ~ 1.5 K  curves at two descriptive densities (Vg = 0.58 V and Vg = 0.50 V) are shown in Fig. Ic) is observed at Vg = 0.58 V and observed the supercurrent for an elongated range of density with Ic (~ 1 to 15 nA). The temperature dependence of the resistance peaks is nearly invisible, as the temperature is enhanced above ~ 5 K  , 140. Thit cell) , 141. Thn valley  and the  K) Fig. b. The Rx5 K Fig. c; it cou5 K Fig. d. The Ar and hBN , 148; thL mode illustrates the influence of the twisting angle-dependent electronic band overlaps, onto the Raman spectrum. The continuous variation in optical and electrical properties of tBLG is strongly dependent on the twisting angle (θ) among the two graphene layers. We believe that the development and variation in the optical properties of tBLG would be extensively used in the future in the field of optoelectronics. The tBLG devices displayed non-monotonous conductivity variation, which reveals a semiconductor to metallic transition. The superconducting properties observed in tBLG are due to the electron interactions, which can distinctly influence the properties of moiré superlattices at higher densities and smaller twisting angles. There are quite a few challenges that are related to achieving a control over the twisting of two graphene layers for the development in the fabrication and characterization of twisted bilayer graphene (tBLG). It is expected that theoretical studies will be published in the future to search for novel superconducting and insulating phases of tBLG at a lower temperature.The objective of this review paper is to provide detailed information regarding the fabrication of twisted bilayer graphene (tBLG) via different methods, its properties, as well as its technological applicability. The tBLG-related research field has developed at an enormous speed. The prominent tBLG fabrication methods such as micromechanical exfoliation, CVD, graphene flake pickup, CRS, stacking methods, and their unique properties are summarized in the initial sections. The control over the twisting of two graphene layers is the major challenge in the fabrication of tBLG. The twisted bilayer graphene (tBLG) is a novel arrangement, which shows the basic properties are different from those of the stacked bilayer graphene. The variation in line width and position of the (ZO′)


Pituitary pars intermedia dysfunction (PPID) is the most prevalent endocrine disorder of older equids. To date, key research areas likely to have the greatest impact on equine health have not been identified. In human medicine, public and patient involvement is widely used to inform research agendas. This study aimed to engage with veterinary surgeons and horse owners to identify evidence gaps (‘uncertainties’) and prioritise these into a list of the 10 most important PPID research questions. The James Lind Alliance (JLA) Priority Setting Partnership (PSP) Framework was adapted. Questions about the diagnosis, treatment and prognosis of PPID were gathered via an online survey targeting veterinary surgeons and horse owners with experience of PPID. Thematic analysis was used to form a longlist of collated indicative research questions (CIRQs), defined by the JLA as true ‘evidence uncertainties’ when not answered by a published, clinically relevant, up-to-date systematic review. In an interim prioritisation survey, questions were ranked by weighted scores creating a shortlist of 25 that were taken forward to the PSP workshop, where participants reached a consensus on the top 10. Useable responses containing ≥1 question were received from 524 respondents . After screening for relevance, 1,260 individual questions were included in thematic analysis, resulting in 47 CIRQs. Interim prioritisation votes for the CIRQs were received from 360 respondents. The top 10 questions prioritised at the PSP workshop focused on long-term prognosis, diagnostic accuracy, efficacy of pergolide treatment, alternative treatment/management strategies and potential treatment options for poor responders to pergolide. The quantity of questions generated indicates an extensive number of uncertainties regarding the diagnosis, treatment and prognosis of PPID. The top 10 research questions will help to inform key areas for evidence synthesis and knowledge translation, and to direct future research into areas most important to end users involved in caring for and treating animals with PPID. Pituitary pars intermedia dysfunction (PPID) is a common age-associated equine neurodegenerative disorder ,2. WhileEnsuring that research is relevant and applicable to those who can improve patient care is essential. However, researchers do not always investigate areas or answer questions important to the end users ,21. InclVeterinary surgeons and horse owners with experience of PPID are best placed to identify questions about the disease most in need of answering. Therefore, the aim of this study was to engage these end users in order to identify their top 10 research priorities for the diagnosis, treatment and prognosis of PPID.This study did not include animal participants, therefore international, national, or institutional guidelines for humane animal treatment are not applicable. This project received institutional ethical approval from the University of Liverpool and Animal Health Trust. Following institutional ethical approval, the six steps of the JLA framework  were adaIdentification of, and contact with, collaborators to form a steering group.Development and dissemination of surveys to the target audience to gather questions they have regarding PPID.Collation, categorisation and refining of the questions submitted by participants into a longlist, and formatting these collated questions in PICO  format where possible.Searching the literature to identify if the questions are ‘uncertainties’. An uncertainty is defined by the JLA as “a question which cannot be answered by a relevant, up-to-date systematic review” .If >30 uncertainties are identified, interim prioritisation is undertaken to form a short list of 25 questions taken forward to the PSP workshop.The organisation of a PSP workshop.A steering group was established to run and oversee the Priority Setting Partnership (PSP). The steering group consisted of veterinary surgeons, including specialists in evidence-based medicine and equine internal medicine, as well as horse owners with experience of PPID. A protocol detailing the specific objectives of the PSP was developed in accordance with the JLA guidelines ,33 S1 A and adapth April 2017 to 9th June 2017.A survey was developed to collect questions from respondents based on the JLA guidelines using the freely available online survey tool, Kwiksurveys  S2 Appe. The surResponses were downloaded into a Microsoft Excel spreadsheet and anonymised. Each individual question was screened for relevance and to ensure the inclusion and exclusion detailed in the JLA PSP protocol  were metThe literature was searched for relevant, up-to-date systematic reviews using appropriate databases including MEDLINE, CABI, SCOPUS, Web of Science (WOS) and the online database of citations for systematic reviews of relevance to veterinary medicine and science VetSRev . Broad srd October 2017 to 20th November 2017. Questions were ranked via weighted scores, depending on the number of votes received, to ensure equal weighting of veterinary surgeon and horse owner responses. Separate rankings were then combined to form a final ranked list of all questions. The top 25 questions were taken forward to final PSP workshop.From the initial survey, more than 30 uncertainties were identified; therefore an interim survey was undertaken to prioritise which uncertainties should be included in the PSP workshop . A link Participants from both surveys who expressed an interest in participating further, and had provided contact details for this purpose, were invited to attend the final PSP workshop. The final priority setting was conducted in a face-to-face workshop using both small and whole group discussions, utilising an adapted nominal group technique ,37. ThisA total of 524 usable responses, which contained at least one question about diagnosis, treatment and/or prognosis, were received from veterinary surgeons and/or horse owners with experience of PPID in the initial online survey. The majority of responses were from owners , of which 438 currently owned a horse with PPID and 47 had previously owned a horse with PPID. The remaining 39 responses were from veterinary surgeons, of which 35 were currently in practice treating horses with PPID, and four were also current owners of a horse with PPID. The majority of respondents were from GB , and 7.3% (n = 38) were from other regions including North America (n = 12), Europe (n = 10), Ireland, the British Channel Islands and Isle of Man (n = 9), Australasia (n = 6) and Asia (n = 1). A further two respondents did not provide information regarding their country of residence.The process of rationalising the list of questions is summarised in th December 2017 . Median participant ratings for their overall experience, usefulness, purpose and organisation of the PSP workshop out of 10, were 9.5, 9, 10 and 10, respectively.This PSP achieved engagement with horse owners and veterinary surgeons across two phases of prioritisation to identify research priorities for PPID. The JLA framework was successfully applied to an equine disease of complex pathophysiology, indicating this methodology could be effectively applied to other equine diseases. The research priorities, within the pre-defined topics of diagnosis, treatment and prognosis, included: [i] long-term prognosis, [ii] diagnostic accuracy, [iii] efficacy of pergolide, [iv] alternative treatment/management strategies and [v] potential treatment options for poor responders to treatment with pergolide. As the study was conducted in GB and respondents were primarily from GB, differences in horse populations, management and treatment practices around the world means the questions raised here may not be globally representative.The PSP followed a rigorous and transparent predefined process to create a top 10 list of shared research priorities. The process gathered a large number of responses, comparable with other JLA PSPs ,40. The Various methods were used to distribute the survey with some being more successful than others. Advertising via social media was effective for recruiting horse owners but not veterinary surgeons. A large number of veterinary surgeons were contacted via BI’s mailing list. However, the number of veterinary responses compared to horse owners was disappointing. This may have been for a number of reasons, such as they were not interested in engaging in this type of research, the open question design of the questionnaire discouraged them from participating or they felt there were no gaps in the evidence and therefore did not have a question to pose. A more targeted approach or a prior, formal collaboration with veterinary practices may have improved veterinary responses. However, a low response rate from veterinary surgeons and veterinary practices has been noted in other studies ,42. Explet al (2014) [Despite the low number of responses, questions posed by participating veterinary surgeons did not markedly differ from those posed by owners. Around a quarter of questions raised by participants were not specific to diagnosis, treatment or prognosis and instead covered other PPID-related subjects. This is comparable the previous veterinary PSP conducted by Dean l (2014) . The majl (2014) . Many ofl (2014) . This alThe ‘Choose Ten’ interim prioritisation approach was chosen because it is an uncomplicated way of allowing participants to consider the whole list then make choices that involve genuine shortlisting . DespiteDuring the adaptation of the JLA protocol, it was decided that the JLA definition of an ‘uncertainty’ would be applied for the equine veterinary setting. There are few systematic reviews in equine medicine; at the time of writing only 23 were available on the VetSRev database. This meant it was likely all questions posed by participants would be defined as uncertainties. However, it was agreed by the steering group that the level of certainty could not be lowered and the quality of evidence should remain the same across fields. Systematic reviews collate data from numerous studies and offer the highest level of evidence , and if The final PSP workshop allowed an open and thoughtful exchange of views between horse owners and veterinary surgeons. This enabled consensus to be developed and facilitated the identification of the top 10 research questions. Both groups were represented by an appropriate number of participants ,33. All Two of the top 10 questions related to the accuracy and interpretation of diagnostic tests. In several studies, utilising a variety of different clinical reference standards, the commonly used basal ACTH test has been reported to have good sensitivity and specificity ,50,53–55The majority of questions centred around treatment , with quPriority questions identified in this PSP are potentially methodologically complex to answer in terms of study design, implementation, ethical concerns and financial limitations. The JLA process is not concerned with how the questions raised will be answered: its function is to provide a platform for the involvement of end users –27. HoweThis study shows that horse owners and veterinary surgeons can be involved in identifying and prioritising uncertainties. The involvement of veterinary surgeons and owners at this stage of the research process has the ability to improve available evidence, ensure research is relevant to end users and aid decision making. During the PSP process horse owners acted as a proxy for the patient. The JLA has previously been utilised in this way for feline medicine . This adThe JLA methodology can be successfully adapted into an equine veterinary setting and applied to the diagnosis, treatment and prognosis of PPID in horses. The response and quantity of questions generated indicates an extensive number of uncertainties about the disease. However, as the research was undertaken in GB, it is possible that the research questions prioritised may differ from unanswered questions of veterinary surgeons and horse owners in other countries. Identifying the top 10 research questions for a disease or condition, especially those that require long-term management, will help to direct evidence synthesis, knowledge translation and future research into areas most important to the end users.S1 Table(PDF)Click here for additional data file.S2 Table(PDF)Click here for additional data file.S1 Appendix(PDF)Click here for additional data file.S2 Appendix(PDF)Click here for additional data file.S3 Appendix(PDF)Click here for additional data file.S4 Appendix(XLSX)Click here for additional data file.S5 Appendix(XLSX)Click here for additional data file.S6 Appendix(XLSX)Click here for additional data file.


It is assumed that THK5317 PET/MRI may also depict tau protein in the skeletal muscles of patients with sIBM. Here we introduced a novel application of tau PET in diagnosis of sIBM in a rare case.Sporadic inclusion body myositis (sIBM) is a chronic progressive idiopathic inflammatory myopathy, with characteristic rimmed vacuoles and sarcoplasmic abnormal tau protein deposits. THK5317, an We presented a 46-year-old woman who suffered from progressive lower limb weakness for one and a half year.Needle electromyography showed myogenic damage. Characteristic myopathological changes of sIBM were discovered, and abnormal tau protein deposits were identified by tau immunostaining. Genetic testing ruled out the GNE myopathy, a hereditary distal myopathy with rimmed vacuoles. The patient was finally diagnosed as sIBM.18F] THK5317 PET/MRI on the patient.We performed  THK5317 PET can reveal muscular tau deposition in vivo, which provides a new and noninvasive diagnostic method for sIBM and offers the opportunity to monitor the progression of tau pathology along with muscle impairment.[ Further research investigated that a variety of abnormal protein deposits similar to those in the brain of patients with Alzheimer's disease (AD) have been discovered in sIBM muscle fibers, such as phosphorylated tau protein. This suggests that sIBM and AD have similar pathogenesis and pathological characteristics. In vivo study on patients with AD using [18F] THK5317 has shown considerable cortical uptake and temporal lobe retention, in comparison to healthy control individual. Based on the similarities of pathologic features shared by sIBM and AD, we tentatively display tau protein deposits in vivo by using [18F] THK5317 PET/MRI in a female patient with typical pathological features of sIBM. This is the first reported sIBM case who was performed by [18F] THK5317 PET/MRI and muscle biopsy.Sporadic inclusion body myositis (sIBM) is described as an uncommon, progressive, inflammatory myopathy, mostly involving patients older than 50.This study passed the ethical review by the Medical Ethics Committee of Chinese PLA General Hospital.2A 46-year-old woman was presented to our hospital with progressive lower limb weakness for one and a half year with no family history of neuromuscular diseases. Her previous medical history was normal. Neurological examination showed normal speech and mental status, and the cranial nerve examination was normal. Manual muscle strength testing was entirely normal in the upper extremities, and lower in bilateral proximal (grade 3) and distal (grade 4) of pelvic limbs. Neck flexor and extensor strength were normal. Deep tendon reflexes were normal, without Hoffman signs or clonus, and plantar responses were flexor. The sensory examination was normal. No truncal or appendicular ataxia was noted. Serum creatine kinase (CK) level was 689.6 U/L , and lactic dehydrogenase (LDH) level was 243.7 U/L .The patient's nerve conduction studies were normal. Her needle electromyography demonstrated fibrillation potentials in quadriceps and anterior tibialis muscle, with small motor unit potentials and rapid recruitment in these and upper and lower extremities muscles, including first interosseous muscle, quadriceps and anterior tibialis muscle. Muscle biopsy of the left quadriceps muscle revealed some necrotic fibers, rimmed vacuoles in muscle fibers with basophilic deposits Fig. A, B, and18F] THK5317 PET/MRI was performed on the patient after she signed the informed consent. Forty minutes after intravenous injection of [18F] THK5317, whole body distribution of radioactivity was measured with a Siemens PET/MRI scanner (MAGNETOM Biograph mMR). PET image reconstruction based on MRI was performed to analyze the difference of radioactive uptake in muscles. Reading of [18F] THK5317 PET/MRI image was performed by at least two nuclear medicine physicians, looking for focally enhanced uptake within skeletal muscles. The case presented with increased [18F] THK5317-SUV levels in the biopsy site of the left quadriceps with corresponding tau positive immunostaining. Tau uptakes of bilateral quadriceps were increased to SUV level of 0.73/0.67 (right/left) (Fig. Subsequent  THK5317-PET can depict muscular tau deposits in vivo. Although muscle biopsy can reveal abnormal deposition of tau protein in sIBM, but it cannot provide the condition of tau deposition within all skeletal muscles. Our case further confirms that the muscles of patients with sIBM can show tau-tracer binding in vivo. The application of tau PET has allowed identification of tau deposition in vivo and can help to improve for the ability and efficiency of sIBM diagnosis.In our study, we introduced a novel application of tau PET in diagnosis of sporadic inclusion body myositis in a case which is diagnosed with pathological definite sIBM. To our knowledge, this is the first report on using of the tau PET/MRI within sIBM patient, which presented a significantly increased uptake of tau protein within involved muscles. This suggests that  THK5317 could be an excellent imaging agent for tau protein in sIBM patients and offer the opportunity to monitor the progression of tau pathology along with muscle impairment.Maetzler et al previously reported that 18F] THK5317-PET can reveal muscular tau deposition in vivo, which provides a new and noninvasive diagnostic method for sIBM and offers the opportunity to monitor the progression of tau pathology along with muscle impairment. While due to only one patient included, our findings must be considered as preliminary and further study in a larger number of participant patients is needed to confirm these findings.In conclusion, [We thank the patient and her family for their kind cooperation.Conceptualization: Ke Li, Qiang Shi.Data curation: Yutong Zhang, Ke Li.Formal analysis: Yutong Zhang.Funding acquisition: Ke Li, Chuanqiang Pu, Qiang Shi.Investigation: Yutong Zhang.Methodology: Haodan Dang, Jiajin Liu.Project administration: Qiang Shi.Resources: Ke Li.Supervision: Chuanqiang Pu.Visualization: Haodan Dang, Jiajin Liu.Writing – original draft: Yutong Zhang, Ke Li.Writing – review & editing: Qiang Shi.


Moreover, the minimum TWR obtained for graphene-based dielectric, i.e., 0.17 mg/min is approximately 1.5 times less than that achieved with kerosene.Titanium alloys, especially Ti-6Al-4V, which is considered a difficult-to-cut material, bears numerous applications in aerospace and biomedical sectors. The criticality of the accurate formation of the machined cavity for the said applications and properties of Ti-6Al-4V accentuated the use of electric discharge machining (EDM). However, the issues of lower material removal rate (MRR) and tool wear (TWR) discouraged the use of EDM. These inherent issues hold a pivotal role regarding the sustainable machining of Ti-alloy. Therefore, in this research the potentiality of kerosene-based dielectric, having graphene nanoparticles, is comprehensively examined for the sustainable EDM of Ti-6Al-4V, which was not focused upon yet. Experimentation was performed under Taguchi’s design (L18) with three types of electrodes, namely Aluminum, Brass and Copper. In total, 36 experiments were conducted, of which 18 were with graphene-mixed dielectric and the remaining were with kerosene. Experimental results reveal that the brass electrode with negative tool polarity yields higher MRR for both types of dielectrics. The maximum MRR (7.602 mm Titanium (Ti) and its alloys are extensively employed in the manufacturing of different parts/products in many industrial and commercial applications. Especially, Ti-6Al-4V bears a range of industrial applications, owing to its fabulous characteristics, such as high-temperature stability, remarkable strength-to-weight ratio and excellent corrosion resistance. These attributes make Ti-6Al-4V useful in the chemical industry, medical science, aerospace, automotive industry, energy sector, food industry, and defence industry etc. ,2,3. DesEDM is considered as a valuable machining technique for the cutting of hard-to-machine materials, such as Ti-6Al-4V ,11,12. HMRR is described as the volume of the material dislodged from the specimen during the machining time. The productivity of EDM typically depends on the MRR, which reflects the operative speed of production . Another2O3 nanoparticles in deionized water lowers the micro-cracks on the machined cavity in the EDM of super alloy Inconel 825 with a copper electrode [Many researchers have revealed that the dielectric with particles is generally preferred for improving MRR and TWR in EDM. Erden and Bilgin  investiglectrode . Anotherlectrode . The outlectrode .Although significant efforts have been made in the past for achieving high MRR and low TWR in the EDM of Ti6Al4V, considering different means, i.e., by adding certain additives or by adjusting the parameters or by some modification in the cutting mechanism. However, the potential of graphene nanoparticles mixed with kerosene dielectric has not been explicitly studied so far in the EDM of Ti6Al4V. It is pertinent to mention that graphene has attracted the focus of the researchers, owing to its remarkable characteristics. Therefore, this research aims to comprehensively inspect the influence/impact of graphene-based dielectric on the EDM of Ti6Al4V in terms of MRR and TWR. The selection of these two response attributes is based on their well-proven contribution towards ensuring the sustainability of the machining process. The achievement of higher MRR by the addition of graphene in the kerosene at same electrical input is a depiction that lesser resources are consumed at the power generation station. So, the low level of pollution contributed to the environment if graphene-based dielectric is engaged in EDM. In other words, it helps to maintain a clean environment. The aspect of TWR is linked with sustainability as it accounts for the wastage of material. Hence, its lower value is deemed necessary for warranting the sustainability of the EDM. Considering the importance of the set responses, experimentation has been planned under Taguchi’s design (L18). In total, 36 experiments were performed: 18 with kerosene and the remaining 18 with graphene-mixed kerosene. The experimental results were analysed with the statistical tools. An optical microscopic analysis has also been done for providing the insight of the parametric effects in relation to the selected responses. Optimal settings have also been developed, based on the parametric trends.Ti-6Al-4V was taken as a workpiece herein, which has numerous applications in aerospace, automobile, chemical, and biomedical applications . The worIn this setup, a separate container with a stirrer inside was used for adding graphene nanoparticles in the kerosene. The stirrer was used to ensure the homogeneity of the mixture during experiments. In each of the experiments, a cavity with a diameter of 9 mm and depth of 0.3 mm was produced, using an electrode of 9 mm. The three different electrode materials, namely copper, brass and aluminium were engaged in this research to select the best tool material for the sustainable cutting of the selected work part. The cross sections of all the electrodes are shown in Pulse time ratio (PTR) is the ratio of on-time to off-time. The selection of these control variables was made because their impact was rated significant with regard to MRR and TWR in the EDM of Ti6Al4V ,42,43,44Experimentation was planned according to Taguchi’s experimental design, which was proved as a promising design technique in a similar study conducted on the same material . ConsideInitial and final masses of workpiece and tool have been measured. MRR was calculated by volumetric method, whereas TWR was assessed in terms of mass reduction. MRR and TWR were found using the relations mentioned as Equation (1) and Equation (2), respectively.x, y, d and t represent lateral dimension, axial dimension, depth and cutting time, whereas, iM and fM denote the initial and final masses of the electrode, respectively.Here, After calculating the MRR and TWR for all the experiments, the results have been comprehensively analysed using statistical techniques, such as parametric line plots and bar charts, etc. These plots have been drawn considering the mean values of the responses. Against each of the parametric levels, the values of MRR have been noted for all the experiments conducted on the specified level value of the parameter. As polarity has two levels, this means that nine experiments were performed at each tool polarity. However, in a case when a parameter has three levels, as in the case of current against each of the levels, six experiments were performed. For analysis purposes, the mean value of the response against the defined parametric level was computed. Since current has three levels, this means three data points are available that are linked with a line to depict a parametric trend for the set response, i.e., MRR. The similar procedure is opted for in the case of TWR. Moreover, optical microscopic analysis was performed to have physical evidence of the findings. A detailed comparison has been made for the results achieved with the graphene-mixed dielectric and simple kerosene. Finally, an optimal combination of input variables has been developed based on parametric analysis.Experimental results are provided in It is observed that discharge current is the main governing factor that affects the MRR in the EDM of Ti6Al4V using a graphene-based dielectric, as illustrated in As the value of current increases from 6 to 8 amps, the MRR decreases because of the presence of graphene particles. Their availability in the discharge gap creates more hindrance in front of sparks, which results in a lesser MRR. However, the magnitude of MRR sharply improved as the discharge current value raised from 8 to 10 amps. The rise in MRR is associated with the generation of intense heat energy in the gap between the tool and workpiece. At high energy, a larger quantity of material was removed in the form of melted debris from the workpiece surface, resulting in higher MRR. In any case, given the large amount of heat input, the higher the magnitude of current, which also yields powerful discharges. These discrete penetrating discharges intensively hit the liquid material in the liquid puddle and caused the ejection of more material, leaving deeper craters in the machined region . The avaThe experiment results declared that the kerosene-based dielectric showed a somehow similar trend for MRR, as that was portrayed by the graphene mixed dielectric. The MRR is decreased with the rise in current up to 8 amps due to the deposition of the carbon layer over the surface of the tool, which causes improper discharging between the workpiece and the tool . SubsequBy examining the results (one with a graphene-based dielectric and other with a kerosene-based dielectric), it has been confirmed that the material removal rate is higher for a graphene-based dielectric. This is attributed to the fact that the presence of graphene nanoparticles influences the spark erosion phenomenon in EDM. Their existence in the dielectric fluid provides a powerful explosion, which induces a strong penetrating heat flux in the workpiece. Thus, a higher MRR is achieved in the EDM of Ti6Al4V with the application of graphene nanoparticles in the dielectric in contrast to simple kerosene, as demonstrated in Three electrodes—aluminium, brass and copper—were used for experimentation. Their effect is shown in The cutting performance of all the electrodes was also compared in terms of MRR in the EDM of the Ti-alloy using a graphene-mixed dielectric, as shown in In case of kerosene dielectric, the electrode of Al provides the highest MRR amongst the available alternatives. The decreasing trend of MRR is observed for the kerosene-based dielectric from aluminium to copper, as presented in Polarity is another important control variable for getting higher MRR. Two types of polarities are engaged in the EDM process, i.e., positive and negative polarity. Usually, polarity refers to the “polarity of the tool”. Positive polarity means positive polarity of the tool and, similarly, negative polarity designates the negative polarity of the tool. In the EDM process, if the tool is positively charged then obviously the workpiece is negative and vice versa. The effect of polarity on MRR in the EDM of Ti6Al4V using both kerosene and graphene-based dielectrics is demonstrated in However, the MRR found at negative polarity with the graphene–kerosene mixture is notably higher in contest to that achieved with kerosene. Hence, negative polarity is more suited when graphene particles are mixed in the dielectric for getting the high value of MRR. It has been confirmed from the results that MRR is higher when machining has been performed at negative polarity because the spark formation is greater, which forced the material to wear out.Pulse–time ratio (PTR) is another important factor which greatly affects the MRR in EDM, as highlighted in In the case of the kerosene dielectric, a decreasing trend of MRR is observed for a pulse–time ratio from 0.5 to 1.5, as presented in Flushing is a phenomenon of removing debris from the gap between tool and workpiece. It is considered as an important function in Electric Discharge Machining. There are various types of flushing techniques, such as pressure flushing, suction flushing, and jet flushing, etc. Each technique has its own application, as per the need and requirement. M.M. Makenzi et al.  reportedThe larger value of flushing pressure provides better MRR when the graphene-based dielectric is employed, as depicted in the The effect of spark voltage on the defined response by applying the two types of dielectrics in EDM of Ti-alloy is provided in The effect of discharge current on TWR is shown in The micrograph shown in The comparison of the TWR achieved against the two different dielectrics revealed that the rate of tool wear is significantly lower with a graphene-based dielectric if an 8 A current is used in contest to that found with kerosene.The influence of the electrode material for the set response is shown in the plot presented in The one-to-one comparison of the electrode materials in terms of TWR was also performed and is highlighted in It is noticed that the magnitude of TWR is different at positive and negative tool polarities in the EDM of the selected workpiece material, as demonstrated in In a nut shell, the positive polarity of the tool is appreciated in minimizing the wear of the tool. This polarity of the tool ensures the excessive heat dissipation in the surface of the workpiece at the end of the discharge duration and helps in the stabilisation the spark. Ultimately, TWR is decreased.on from 25 to 50 µsec while keeping Toff constant at 50 µsec. This carbon layer acts as a wear-resistant layer for the electrode and assists in reducing its wear. Another reason that contributes to the lowering of TWR is the expansion of the plasma channel at larger values of on-time. Such a kind of expansion of the plasma channel hinders the effective transfer of heat energy to the workpiece and the tool as well. Since a meagre heat input is experienced by the tool, thereof its wear in notably reduced. It is pertinent to mention that the trend of said control variable is similar for graphene-mixed and kerosene dielectrics in the EDM of Ti6Al4V, as depicted in The effect of the pulse–time ratio (ratio between pulse on-time to pulse off-time) on tool wear rate is illustrated in the Flushing time is the time which is required to remove the debris between the workpiece and electrode gap. The impact of flushing time on tool wear rate is displayed in The behaviour of flush time (under kerosene as dielectric) for TWR is dissimilar to that observed in the case of nano particle slurry. Initially, TWR decreases with the rise in said input parameter up to 6 µsec but, afterwards, the opposite trend is noticed. The lowering of TWR until 6 µsec is credited to the solidification of the melted droplets on the electrode surface because of the phenomenon of quenching . HoweverThe influence of spark voltage on TWR using the graphene- and kerosene-based dielectric is provided in Considering the effects of all the parameters accumulatively, it is concluded that the optimal combination of parameters for achieving the maximum MRR at negative tool polarity using brass under the graphene-mixed dielectric is current = 10 A, pulse–time ratio 1, flushing time = 6 µsec and spark voltage = 4 V. On the other hand, to get a lower value of TWR, the most preferable levels of parameters are  under graphene nanoparticle slurry as the dielectric. The optimum conditions in the case of the kerosene dielectric are current (6 amps), electrode material (copper), polarity (positive), pulse–time ratio (1.0), flushing time (6 µsec), and spark voltage (3 V) as present in 4 S/m. Therefore, the presence of graphene nanoparticles influences the discharge characteristics. Their availability is a source of plasma channel’s expansion between tool and workpiece. Ultimately, the strength of the discharge breakdown got affected. These particles also played a pivotal role in the flushing of etched chips, thus, reducing the probability of abnormal sparking. Subsequently, higher MRR is the outcome. Furthermore, in the initial discharge phase of EDM the current magnitude gradually improved which reduced the impact of electron-to-electrode attack. Hence the material loss from the electrode surface notably reduces.It is inferred that, when graphene nanoparticles are used in the kerosene dielectric, then the material removal rate is enhanced, and tool wear rate is reduced significantly. Basically, the conductivity of these particles is quite appreciable, i.e., 8 × 103/min, which is 64.5% higher in comparison to the maximum MRR obtained using the kerosene dielectric, i.e., 4.62 mm3/min.The graphene-based dielectric outperforms MRR when compared with kerosene. The maximum value of MRR achieved with the graphene-based dielectric is 7.60 mmWith respect to the tool material, the electrode of brass provides the highest value of MRR when graphene mixed dielectric was used, whereas the maximum MRR in the case of kerosene is obtained with the aluminium electrode.The tool wear of the Cu electrode is found to be minimal (0.17 mg/min) when graphene nanoparticles are added in the kerosene. This value of is approximately 1.5 times lower than that achieved with kerosene only.The magnitudes of MRR and TWR are especially sensitive to the variation in the tool polarity. The MRR and TWR are both at maximum at negative polarity. Hence, negative polarity is good for achieving a high material removal rate. However, tool wear rate for all electrode materials is lower at positive polarity, thus positive tool polarity is suitable for TWR.The optimal combination of parameters for achieving the maximum MRR at negative tool polarity using brass under the graphene-mixed dielectric is current = 10 A, pulse–time ratio 1, flushing time = 6 µsec and spark voltage = 4 V.The minimal magnitude of TWR was attained with the positive polarity using a copper electrode in graphene-based slurry while keeping the values of current, pulse–time ratio, flushing time and spark voltage at 8 A, 1, 4 µsec and 3 V, respectively.This research focuses on evaluating the cutting performance of the graphene-based kerosene dielectric for the two core contributing aspects (MRR and TWR) of the sustainable electric discharge machining of titanium alloy (Ti6Al4V). Experiments were performed using three different electrode materials, i.e., aluminium, brass and copper, at both positive and negative tool polarities. In total, 36 experiments were performed; 18 were with kerosene and the rest of the experiments were with the graphene-based dielectric under L18 Taguchi design. The dielectric is used with the powder-mixed graphene-based nanoparticles. The MRR and TWR have been investigated using the graphene dielectric to achieve the optimum parameters for the machining of titanium alloy. The selection of the most preferable tool material with suitable polarity was carried out in order to have maximum material removal rate and minimum tool wear rate. Based on the experimentation findings and their detailed dissuasion, along with the physical evidence, the following conclusions are drawn:Comparing the results obtained for graphene mixed dielectric for the kerosene, it has been revealed that the addition of the graphene nanoparticles is appreciable in achieving the sustainable EDM of Ti-alloy.In the future, a detailed investigation will be carried out seek the impact of particles’ morphology on the cutting characteristics. Moreover, the surface integrity of the machined cavity will also be comprehensively examined.


Tachycineta bicolor). We address two questions: (1) do the cloacal bacterial communities differ between female and male tree swallows within a population? and (2) do pair-bonded social partners exhibit more similar cloacal bacterial communities than expected by chance? To answer these questions, we sampled the cloacal microbiome of adults during the breeding season and then used culture-independent, 16S rRNA gene amplicon sequencing to assess bacterial communities. Overall, we found that the cloacal bacterial communities of females and males were similar, and that the communities of pair-bonded social partners were not more similar than expected by chance. Our results suggest that social monogamy does not correlate with an increased similarity in cloacal bacterial community diversity or structure. As social partners were not assessed at the same time, it is possible that breeding stage differences masked social effects on bacterial community diversity and structure. Further, given that tree swallows exhibit high variation in rates of extra-pair activity, considering extra-pair activity when assessing cloacal microbial communities may be important for understanding how these bacterial communities are shaped. Further insight into how bacterial communities are shaped will ultimately shed light on potential tradeoffs associated with alternative behavioral strategies and socially-transmitted microbes.Host-associated microbial communities can influence the overall health of their animal hosts, and many factors, including behavior and physiology, can impact the formation of these complex communities. Bacteria within these communities can be transmitted socially between individuals via indirect  or direct  pathways. Limited research has been done to investigate how social interactions that occur in the context of mating shape host-associated microbial communities. To gain a better understanding of these interactions and, more specifically, to assess how mating behavior shapes an animal’s microbiome, we studied the cloacal bacterial communities of a socially monogamous yet genetically polygynous songbird, the North American tree swallow ( Host-associated microbial communities can contribute to the overall health of their animal hosts –4, and mTachycineta bicolor) and house sparrows (Passer domesticus). More recent work using culture-independent methods has revealed that pair-bonded social partners experimentally blocked from making cloacal contact have significantly less similar cloacal bacterial communities compared to control pairs in black-legged kittiwakes (Rissa tridactyla) )munities . Given tStaphylococcus spp., Campylobacter spp., Salmonella spp., and Shigella spp. In our study, we used culture-independent, next-generation sequencing. We did not find that any of the cloacal bacteria they cultured were members of the core bacterial communities of birds within our study population. While Staphylococcus spp. and Lactobacilli were detected, their relative abundances were <0.001%. This suggests that culturing of cloacal bacteria may not consistently result in isolation of the most dominant bacteria in the system. It is also possible that the bacteria cultured by Lombardo et al. [Previous work examining the similarity of the cloacal bacteria of social partners in tree swallows used culture-dependent methods . The isoo et al.  are rareIn conclusion, our results suggest that the cloacal bacterial communities of female and male tree swallows are similar within our study population and that pair-bonded social partners do not share more similar cloacal bacterial communities than expected by chance. Given that tree swallows exhibit high variation in rates of extra-pair activity, we argue that considering rates of extra-pair activity or the number of sexual partners per bird when assessing cloacal bacterial communities may be important for understanding how cloacal bacterial communities are structured. Also, since cloacal bacterial communities comprise bacteria derived from both the reproductive and digestive tract, diet should also be considered when assessing cloacal bacterial communities. Lastly, we suggest that pair-bonded social partners should be sampled simultaneously to control for any temporal shifts in individual behavior and physiology that may influence shifts in cloacal bacterial community structure across breeding stages.


With the rapid development of wearable and portable electronic devices, it is increasingly important to develop conductive paper-like films (CPFs) with the characteristics of light, thin and self-supporting. In this paper, nanofibrillated cellulose (NFC) was used as reinforcing phase of film-forming to combine with graphene oxide (GO). Then graphene-based CPFs were prepared by directly reducing the GO/NFC composite film without any additional adhesives, which effectively avoided the difficulties of dispersion and combination with other materials caused by direct using of high content graphene. Meanwhile, three representative reduction methods for direct reduction of GO/NFC composite films were also compared. The results show that 450 °C thermal reduction and hydroiodic acid reduction were more effective than ascorbic acid reduction. On this basis, hydroiodic acid reduction and thermal reduction were used to discuss the effect of NFC addition to the conductivity of the film. This occured when increasing the content of NFC from 10% to 50%, the electrical conductivity of the composite film by hydroiodic acid reduction decreased from 153.8 S/m to 22.2 S/m. While the conductivity of composite film increased first and then decreased after thermal reduction both at 450 °C and 550 °C. What’s more, when NFC content was about 16.6% the electrical conductivity reached a high level which was 86.21 S/m and 168.9 S/m, respectively. This study provides a groundwork for the further development of graphene-based CPFs with low square resistance and high conductivity in large-scale preparation. Accordingly, three-dimensional conductive papers (CPs) or conductive paper-like films (CPFs) with light, thin, self-supporting and excellent durability features exhibit attracting prospect for applications in wearable device2 hybridization, which has attracted ever-increasing attention by researchers for its excellent electrical, thermal and mechanical properties7. And it also has been widely researched in the preparation of conductive materials by virtue of its high electron mobility and high conductivity8. El-Kady9et al. used LightScribe DVD optical drive to do the direct laser reduction of graphite oxide (GO) films to graphene with high electrical conductivity (1738 S/m), but the method requires high equipment and the laser-scribed process is difficult to control in actual production. Zhang10et al. prepared highly conductive graphene nanomesh films (27800–35400 S/m) by an in-situ carbothermal reduction strategy and well performed in supercapacitors. However, the preparation process is relatively complicated and the efficiency needs to be improved in large-scale preparation. Among various approaches to prepare graphene composite CPs or CPFs, the development of simple, low-cost, large-scale, commercial methods is still a challenge. Kang11et al. used traditional papermaking methods to prepare CPFs with conductivity of 11.6 S/m and square resistance of 1063 Ω/sq by mixing pulp with graphene. It exhibited high electrochemical performances in flexible electrodes for supercapacitors and lithium batteries. While Luong12et al. utilized hydrazine to reduce the mixture of graphene oxide(GO) and nanocellulose to prepare conductive film by filtering, when the graphene content was 10%, the composite film conductivity was 71.8 S/m. Besides, simple solution process such as dipping14, coating15 and casting16 were also studied by researchers. However, in the above report, graphene was combined with other materials at a lower content, the conductivity of the materials was limited which may affect the property of the final device. To fully demonstrate the prominent electrical property of graphene and further improve the electrical conductivity of composites, increasing the proportion of graphene or using graphene as the main component to prepare CPFs is concerned. But in this process, two problems are easy to occur: First, graphene agglomerate easily and disperse in poor state, it may cause local graphitization and affect its performance. Second, the surface inertness of graphene makes it difficult to form a film itself, and it’s also hard to combine well with other materials. So the preparation of graphene-based CPFs and the improvement of its conductive properties need to be further studied.Graphene is a two-dimensional carbon nanomaterial with carbon atoms formed by sp17. While nanofibrillated cellulose (NFC) not only has large specific surface area, high strength, good biodegradability, but also larger in length-diameter ratio which can easily interweave a network structure18. Besides, NFC has high hydrophilicity due to its large amount of hydroxyl groups, and is easy to form films or gelations19. Therefore, in this paper, NFC was used as the enhancement phase of film formation. By adding an appropriate amount of NFC to combine with well dispersed GO into film, the graphene-based CPFs were obtained by direct reduction of the GO/NFC composite film, thus it effectively avoided the difficulties of dispersion and combination with other materials caused by direct using of high content graphene.GO as an oxide of graphene, has a large number of oxygen-containing groups on its surface and edge, showing good dispersion in water. More importantly, it can be reduced into graphene to restore its conductivity22, sodium borohydride23, hydroiodic acid (HI)25 and green reducing agents such as ascorbic acid (VC)26, chitosan27 and glucose28. As an efficient, non-toxic reducing agent, HI can directly reduce GO film into high conductive graphene film without destroying the integrity and flexibility of the film24. When VC is used as reducing agent, RGO obtained after reduction has a good dispersibility, which is beneficial to the further application of the product26. In addition to the chemical reduction method, thermal reduction31 is also an efficient reduction method. The mechanism is that the oxygen-containing functional groups on GO escape from the sheet layer in the form of H2O, CO2 or CO at a high temperature by using GO under the protection of inert gas, then RGO can be obtained.Furthermore, different reduction methods are of notable effect on the conductivity of the reduced graphene oxide(RGO), which accordingly influence the conductivity of GO/NFC composite film after reduction. Commonly used methods for reducing GO are mainly divided into chemical reduction method and thermal reduction method. The high-efficiency reducing agents used in chemical reduction ordinarily includes hydrazine and its derivativesHence, HI reduction, VC reduction and thermal reduction were investigated to prepare graphene-based CPFs by direct reduction of the GO/NFC composite film. The effects of different reduction methods on the surface properties, microstructure and electrical conductivity of the composite film before and after reduction were discussed. On this basis, we also discussed the effect of NFC addition to the conductivity of the graphene-based CPFs, and analysed reasons for the change in conductivity.Bleached eucalyptus pulp, Graphene oxide dispersion . HI , VC, TEMPO, NaBr, NaClO, NaOH . Deionized water was used in this study. Vacuum tube furnace TF1200–200 .32, and washed with HCl (1 mol/L) three times, then homogenized by high pressure to obtain a gel-like NFC.Eucalyptus pulp is first oxidized by TEMPO2). After drying at room temperature (30 °C) for 24 h, the composite film was retained in the following reduction experiments.The above-mentioned prepared NFC and a certain concentration of GO were mixed by ultrasound. The mixed solution with different mass ratio of GO and NFC was prepared respectively (absolute dry mass ratio). Then, filtration of mixed solution into film  HI solution and reduced it in a constant temperature water bath at 90 °C for 1 hour. After that, the residual solution on the film was washed out by ethanol and dried naturally at room temperatureThe GO/NFC composite film was immersed in a sealed container containing VC solution (the mass of VC is 10 times than that of GO), which was reduced in a constant temperature water bath at 90 °C for 1 hour. After that, the residual solution on the film was washed out by ethanol and dried naturally at room temperature.The GO/NFC composite film is placed in a vacuum tube furnace under the protection of nitrogen, the film was heated to 450 °C for 0.5 h, then dropped to room temperature.−1–400 cm−1 was used to identify and analyze the structure and composition of the samples. Microscopic Raman spectroscopy  was used to analyze the microstructure changes of the samples. X-ray photoelectron spectroscopy (XPS) was used to further study the evolution of functional groups. Four-probe  was used to test the square resistance and conductivity of the sample. Multiple measurements and the average values were obtained. Tensile strength (TS), Young’s modulus (YM) and the stress-strain curves of GO films and GO/NFC composite films after different reduction methods were conducted by using the Universal Testing Machine  at a speed of 10 mm min−1 with films 1.5 cm wide and 3 cm long.The surface morphology and microstructure of the samples were analyzed by Field Emission Scanning Electron Microscopy(FESEM) . X-ray diffraction(XRD) patterns were recorded on a Bruker D8 advance X-ray diffractometer using Cu Kα radiation (λ = 0.15406 nm). Fourier transform infrared spectroscopy(FTIR)  with wave range of 4000Figure 2 hybridization when oxygen-containing functional groups were removed.Figure Next, the square resistance and conductivity of graphene-based CPFs were measured, which was shown in Table The relationship between sheet resistance and resistivity is as follows:To gain further insight into the level of the reduction effects of VC reduction, HI reduction and thermal reduction, Raman spectroscopy, XRD, FTIR, XPS were employed to investigate the structural evolution during the reduction process.−1 and G peak at 1575 cm−1 in Raman spectrum is often used to evaluate the sp2 hybrid domain size of carbon materials. What the sp3/sp2 carbon atom ratio can indirectly reflect the degree of disorder in the structure33. Figure 2 would be formed, which decreased the ratio of ID/IG accordingly. By comparing the ratio of ID/IG, 450 °C thermal reduction (0.744) is intense than VC reduction (0.762) due to the formation of larger sp2 hybrid region at high temperature. While the ID/IG ratio of the composite film after HI reduction (1.118) is higher than that of the GO/NFC composite film (1.033), the reason for this is that the removal of oxygen atoms in the reduction process of GO was too intense and it inevitably led to disorder. Although the size of the new hybrid domain is smaller than that of GO, the number of new hybrid domains is larger, which brings about the increasing of ID/IG ratio35.Raman spectroscopy is an effective method to characterize the structural changes of defects and edge groups in carbon materials. The intensity ratio of D peak at 1350 cm37. While 2θ = 10.8° corresponds to the characteristic peak of GO (001) lattice plane38. Additionally, the GO/NFC composite film exhibited the (002) crystal plane of NFC at 2θ = 22.6°, while the characteristic peak of the GO (001) crystal plane and the overlapping diffraction of NFC nearly covered, which indicates the good combination of GO and NFC.In addition, the changes of crystal structure before and after reduction of GO/NFC composite films were also characterized by XRD. Figure 39. When the GO/NFC composite film respectively reduced by VC reduction, HI reduction and thermal reduction, the characteristic peak of 24.8° shifted to large angle in turn. From the formula 2dsinθ = nλ, with the increase of θ angle, the corresponding crystal-plane spacing d decreases. The removal of oxygen-containing functional groups in different reduction processes would affect the spacing between lattice planes, which indicated that the composite film was closer to the crystal structure of graphene after thermal reduction. Meanwhile, the conclusion that new hybrid regions of sp2 were formed and the ratio of ID/IG decreased in Raman spectra was also verified.Figure −1) in the NFC and GO, C-O-C stretching vibration peak (890 cm−1), C-OH stretching vibration peak (1032 cm−1) and COOH stretching vibration peak (1635 cm−1) in GO (identification similar to that reported42). Typically, intensity of peak at 1425 cm−1 belongs to the bending vibration absorption peak of CH2 in NFC43, which was removed only after thermal reduction. This suggests that the carbonation of NFC during thermal reduction. At the same time, the strong absorption peak at 1543 cm−1in thermal reduction and HI reduction can be clearly observed, which caused by the stretching vibration of sp2 chemical bond in the graphene structure42. The results show that the sp2 electron conjugate structure of graphene can be reconstructed effectively after reduction.The change of functional groups of GO/NFC composite films (GO: NFC = 1:1) before and after reduction were characterized by FTIR. As shown in Fig. 40. This indicates the removal of epoxyl, carboxyl, and carbonyl functional groups, and a simultaneous increase in graphitic carbon after reduction.The evolution of functional groups in GO/NFC composite films (GO: CNFs = 1:1) surface before and after reduction were further determined by XPS. After reduction, the C/O atom ratio was increased accordingly in Table Furthermore, stress-strain curves of GO film and GO/NFC composite film (GO: NFC = 1:1) before and after reduction were shown in Fig. Nevertheless, due to the disappearance of hydrogen bonds caused by the remove of oxygen-containing functional groups, the compact lamellar structure is also damaged in varying degrees, which is approved by the description of SEM results Fig. , so the Because the conductivity of the composite film after HI reduction and thermal reduction were much better than that of VC reduction. Thus, the effect that addition of NFC in the conductivity of the graphene-based CPFs was discussed below.Figure Meanwhile, different from HI reduction, the conductivity of the film after thermal reduction increased first and then decreased both at 450 °C and 550 °C. When NFC content was about 16.6%, the electrical conductivity reached a high level which were 86.21 S/m and 168.9 S/m, respectively. That could be the composite film was well intertwined and formed a good conductive network structure.Both of these are beneficial to the electron transport after reduction and make the composite film achieve the best conductivity. When the dosage was less than 16.6%, NFC was not enough to form a uniform net conductive structure. What is the reason for the decrease of conductivity after the reduction is that the graphene was easily deposited and covered which could bring the thermal reduction reaction was not thorough and the carbonization of the NFC was also suppressed. Then, we took the film after HI reduction as a sample (NFC accounts for 12.5%) to do diode path experiment. When the LED lamp touched with the conductive film prepared above, the LED lamp can emit light stably. This indicates that prepared graphene-based CPFs possess excellent conductivity.In this paper, the graphene-based CPFs were successfully prepared by directly reducing the GO/NFC composite film without any additional adhesives, which effectively avoided the difficulties of dispersion and combination with other materials caused by direct using of high content graphene. Moreover, the surface characteristics, microstructure and electrical conductivity of composite films after HI reduction, VC reduction and thermal reduction were compared and analyzed. The results show that thermal reduction and HI reduction were more efficient than VC reduction, and NFC would be carbonized at the same time during thermal reduction. On this basis, we also discussed the effect of NFC addition to the conductivity of graphene-based CPFs prepared by HI reduction and thermal reduction. With the increase of NFC content from 10% to 50%, the conductivity of the composite film decreased gradually after HI reduction. In comparison, the conductivity of the film increase first and then decrease after thermal reduction both at 450 °C and 550 °C. When NFC content was about 16.6%, the electrical conductivity reached a high level, which were 86.21 S/m and 168.9 S/m, respectively. This work provides a basis for the further development of flexible conductive film with low square resistance and high conductivity, and contributes to its potential applications in portable and wearable electronic devices.Supporting information Direct Reduction of Graphene Oxide/Nanofibrillated Cellulose Composite Film and its Electrical Conductivity Research.


IFT) during the last stage of the 30-15 Intermittent Fitness Test, hemoglobin levels, and training load measures during SSG intervals among professional soccer players. Sixteen professional soccer players  participated in this study. Hemoglobin and aerobic performance were first tested, and then a 3-week SSG program was applied using a 3 vs. 3 format. During those 3 weeks, internal and external load of entire sessions were also monitored for all training sessions. Trivial-to-small, standardized differences were observed between sessions for external and internal measures during SSGs. Total distance (TD) and mechanical work (MW) were the only variables that indicated small changes. Large-to-very-large relationships were found between VIFT and external loads: TD , high-intensity running , and MW . Moderate-to-large negative relationships were found between hemoglobin levels and internal loads: Edwards’ TRIMP , %HRmax , and red zone . VIFT had unclear relationships with overall internal loads, while hemoglobin levels presented unclear relationships with overall external loads. In conclusion, no meaningful changes were found between sessions considering the format of play used. Additionally, the detected relationships indicate that VIFT and hemoglobin levels are good indicators of the performance capacity and physiological profile of players during SSGs. Also, the use of SSGs protocols as a monitoring complement of the 30-15IFT is suggested.The purposes of this study were (1) to analyze between-session variations of external and internal load measures during small-sided games (SSGs) and (2) to test the relationships between the maximum speed reached (V The practical operationalization of soccer training in recent years has placed great emphasis on the inclusion of small-sided games (SSGs), which encompass the psychological, physical, technical, and tactical aspects of the game . For coamax (red zone), %HRmax, during SSGs and YYIR performance  than players not living at sea-level locations (14.4 ± 0.7 g·dl−1). The mean VO2max value of the players residing at a moderate altitude (54.1 ml·kg−1·min−1) was also significantly greater than that of the players residing at low altitudes  to analyze the degree of changes/differences in performance between athletes instead of using percentages of changes , employed with the same conditions . The data collection occurred in 2018/2019, in the first 4 weeks of the pre-season. However, training time (between 17:00 and 20:00) and environmental conditions  varied greatly over the data-collection phase. Data related to external load measures were obtained using global positioning systems during all SSG sessions, while internal load was monitored using heart rate monitors. All players involved in the study were professionals and were familiar with SSGs prior to the experimental period.IFT of 17.9 ± 1.2 km/h. All players were informed of the experimental procedures and related risks and gave informed consent before commencing the study. The study protocol was approved by the University Research Ethics Committee. The study followed the ethical standards of the Declaration of Helsinki.Sixteen professional soccer players , all members of a professional club competing in the 2018–2019 season of Qatar Star League (Qatar first division), participated in this study. The inclusion criteria were (i) participation in all the moments of assessment and games; (ii) absence of injuries, physical constraints, or illnesses exhibited during sessions occurred in the period and two weeks prior to the data collection; and (iii) absence of signals of fatigue on assessment days. Players were assigned to different teams (of three elements), and comparisons between teams revealed no meaningful changes in the main outcome (aerobic performance). The baseline fitness levels of players revealed an average Vm, with two sets of three minutes performed in each session. The conditions involved touch limitations (a maximum of three consecutive touches permitted to each player) in accordance with a previous study suggesting ball limitation as a way to increase the intensity .The 3v3+Gk SSG format was used in the present study. This format was repeated over three trials of three ntensity . Three wThe coaching staff, which included one of the authors (a strength and conditioning coach), were directed to ensure the consistency of their supervision during all SSG sessions. Balls were kept near the SSG pitch so that coaches could restart the game immediately if a ball left the playing area. For each format, the teams were balanced based on their members’ physical and technical abilities (as determined by the coach); this reduced the possibility of any strength or weakness bias.max, Edwards’TRIMP, and time spent in the red zone , were analyzed following each session. The HRmax of each individual was extracted from a maximal field-based test  conducted during the pre-season. To standardize Edwards’ TRIMP and red zone measures so that fair comparisons, the corresponding data were divided by minutes played (Edwards’TRIMP.min−1 and Red zone.min−1).Heart rate data were recorded during all SSG sessions using Bluetooth HR sensors  that were synchronized to a validated portable 10-Hz VX Sport 350 GPS units . Each unit was used for the same player across the study to reduce inter-unit variability. HR measures, including HR−1), and mechanical work (MW), for which the numbers of acceleration and deceleration efforts above and below 2.2 m.s2 thresholds were calculated the sum. The thresholds used for acceleration/deceleration efforts (2.2 m.s2) were selected based on practical experiences using the VX GPS system by the coaching staff. All external load measures were standardized by being divided by minutes played  prior to the analysis so that they could be compared across different SSG formats.External load measures were recorded during all sessions using portable 10-Hz VX Sport GPS units , which are valid and reliable according to A blood sample (15 ml) was collected from each participant between 8:00 and 10:00 a.m. The samples were collected with an overnight fast and after a minimum of 12 h of rest (without exercise). Blood samples were centrifuged at 2500 rpm for 10 min, and the serum of each sample was stored. Hemoglobin (g/dl) was determined using flow cytometry.−1 for the first run, and speed was increased by 0.5 km/h for each subsequent run. Players had to run back and forth between two lines positioned 40 m apart. Running pace was set by an automatic beeper to control the running speed when players entered a 3-m zone placed in the middle and at both extremities of the field. During the recovery period, players walked toward the closest line, either at the middle or one of the ends of the running area, depending on where they stopped in the last run. Players were told to complete as many stages as possible, and the test was ended when the players could not maintain the required running speed or could not reach the 3-m zone before the beep three consecutive times. The final velocity registered in the last stage determined the player’s VIFT score , the relationship was deemed unclear; otherwise, the obtained magnitude was deemed to be the observed magnitude (Data are presented as mean and standard deviation (SD) or 90% of confidence limits (CL) where specified. Differences between sessions in terms of training load measures were analyzed using standardized differences or effect size ES; . Qualitary large . A magni perfect . If the agnitude . The staIFT and hemoglobin were 18.0 ± 1.2 km.h−1 and 14.5 ±0.7 g.dl−1, respectively. The mean ± SD of external and internal load measures during different sessions/sets of SSGs are represented in The mean ± SD values of players’ VTrivial-to-small standardized differences were observed in TD  and MW  between sessions  changes were observed in HIR between sessions , time spent in the red zone , and average HR as % of HRmax  between sessions  and HIR  in different sessions  with MW in different sessions .sessions . VIFT alsessions . Howevermoderate-to-large associations were observed between hemoglobin levels and Edwards’ TRIMP , as well as time spent in the red zone  in different sessions . The only clear associations observed between hemoglobin levels and external load measures were the moderate correlations observed when considering HIR in the second sets of the first and second sessions .Inversed sessions . The relIFT and hemoglobin levels with training loads during SSGs intervals among professional soccer players. The main findings were that the external measures had trivial-to-small standardized differences, while all internal measures revealed trivial standardized differences between sessions. VIFT showed large-to-very-large positive relationships with TD, HIR, and MW, while hemoglobin levels showed moderate-to-large negative relationships with TRIMP, time spent in red zone, and %HRmax during different sessions. However, VIFT presented unclear relationships with all internal loads, while hemoglobin levels presented unclear relationships with overall external load.This study was designed to analyze between-session standardized differences of external and internal load measures and the relationships between VBetween-session standardized differences of SSGs were more pronounced only for TD and MW when comparing session 1 and 2 to 3, representing a small degree of change. Meanwhile, HIR presented trivial changes between all sessions. Using different approaches, other study have analyzed between-sets variations of SSGs and reported trivial-to-small standardized differences from the first set to the second set for TD when considering SSGs shorter and longer regimens . Also, tIFT and TD measures revealed in the present study are in line with other study that demonstrated a strong association between Yo-Yo IR scores and total distance covered and high-intensity running speeds during match play, suggesting a strong validity  revealed similar associations with TD  during SSG drills. Also, in the study of r = 0.59) during 6v6 SSGs when considering only the elite population that was analyzed in their study. Considering the HIR measure, moderate-to-large  relationships were previously reported between YYIR2, YYIR1, and the time spent in HIR during a match . In the same way, The large-to-very-large relationships between Vvalidity . In fact a match . The preIFT in the present study. These results contrast with a previous study that reported only a moderate relationship without statistical significance between acceleration measure and YYIR2 during 6v6 SSGs. However, there is a possible explanation for this difference. In fact, shorter formats of play are characterized by more changes of direction and accelerations/decelerations, thus being in line with something that 30-15IFT is also sensitive to . This could mean that MW measures contain a higher factor of unexplainable variability – in fact, previous studies have reported a higher coefficient of variation for those metrics within SSGs  and HR measures during SSGs, which reported large-to-very-large inversed correlations . These results are similar to our results with regard to the unclear associations between hemoglobin levels and the external loads during SSGs  more players can be evaluated at the same time, (ii) SSGs involve technical and tactical demands, and (iii) players are performing soccer training during the test. As practical implications, this study suggests that the internal load and external load of SSGs (considering the outcomes used) are stable across the sessions, while training load is associated with the fitness and physiological status of the players. Based on that, coaches should consider adjusting the stimulus or drills to specific groups of players.Regardless, as far as we know, the present study is the first to analyze the relationships between VIFT is a good indicator of performance capacity during SSGs, given the large-to-very-large relationships between and external measures. Also, hemoglobin levels seem to decrease at higher intensity drills, revealing associations with internal loads. Despite that, VIFT and hemoglobin levels revealed unclear relationships with internal and external measures, respectively. For those reasons, it is suggested that practitioners consider both internal and external loads. It is also suggested that they use SSGs to monitor soccer players’ physiological and performance capacity to complement periodic assessment protocols such as the 30-15IFT.The present study revealed low between-sessions standardized differences for the overall internal and external measures of SSGs, with only TD and MW showing small changes. Thus, it is suggested that tactical behaviors might interfere with those metrics during SSGs. VThe raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by University of Coimbra. The patients/participants provided their written informed consent to participate in this study.SY, AR, FC, and AF lead the project, collected the data, treated the data, wrote the statistical report, and revised the original manuscript. RS and HS wrote and revised the original manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


To confine the terahertz electromagnetic wave, four different fractals are integrated into a supercell, and the coupling and superposition of adjacent resonant cavities form a broadband high-absorption absorber. Using finite element-based full-wave electromagnetic simulation software to simulate the response frequency of 0.4–2.0 THz, we found that the absorber achieves a broadband 1.26 THz range (absorption > 80%) and a relative bandwidth of 106.8%. By adjusting the Fermi energy, it can realize free switching and expand to wider broadband terahertz absorption, by adjusting the polarization angle (Φ) from 0 to 90° to prove that the structure is not sensitive to polarization, the absorber provides a 60° large angle of incidence, polarization for TE and TM the absorption pattern remains basically the same. Compared with the previous work, our proposed structure uses fractal technology to expand the bandwidth and provide dynamic adjustable characteristics with great degrees of freedom. The appearance of the fractal structure reduces the difficulty of actual processing.In this paper, a metasurface Terahertz absorber based on the fractal technology of a graphene geometry resonator to realize ultra-wideband, ultrathin, adjustable double-layer cross-fractal formation is introduced. This paper proposes a dynamically tuned graphene absorbing material. The structure is composed of one- to four-level-fractal graphene pattern layers, MgF The terahertz (THz) or T-ray region of the electromagnetic spectra is defined as the region between infrared (IR) light and microwave radiation, ranging from 100 GHz to 10 THz. This region lacks natural materials with valuable electromagnetic properties and is extremely precious . The tecGraphene is the thinnest 2D material found so far. Graphene has the characteristics of small thickness, high elasticity and durability, and low loss. It exhibits metallic properties when certain conditions are met and becomes one of the most promising materials ,23,24. GFractal theory is closely related to many research fields with a wide range of applications, and the fractal phenomenon of self-similarity will exist. Traditionally, all cells of the fractal have the same geometric shape, the same size, and the same arrangement direction, which are derived from the space filling of the fractal structure and are on the same plane, which reduces the difficulty of processing ,29. Howe2 layer and metal reflective layer. Based on this structure, we mainly integrate two layers of four different fractal structures into a supercell, so a broadband high-absorption absorber is formed. Therefore, our device provides dynamic adjustable characteristics with a great degree of freedom, and our proposed absorber can realize an ultra-wideband, ultrathin, and adjustable planar metasurface terahertz absorber. Using simulation software to simulate the response frequency of 0.4–2.0 THz, we found that the absorber achieves a broadband 1.26 THz range (absorption > 80%), where the center frequency fc= 1.18 THz and the relative bandwidth is 106.8%, achieving broadband absorption by optimizing each fractal structure. In addition, each level of fractal structure we design presents a periodic symmetry pattern, the polarization angle (Φ) is tuned from 0 to 90°, which means that the structure isn’t sensitive to the polarization angles. The oblique angle can be incident at a large angle up to 60° for both TE and TM polarizations is achieved.Compared with the previously reported fractal terahertz metamaterial absorbing materials, the structure we designed has the advantages of easy realization, low cost, miniaturized manufacturing and adjustable degree of freedom, which is useful for future terahertz detectors, terahertz communications and other emerging the realization of terahertz technology is particularly important.In this work, the structure we designed is composed of a one- to four-level fractal graphene pattern layer, MgF2 layer and an ideal electrical conductor , as shown in 2, the relative dielectric constant d =ε 1.9 [mt = 45 μm. The structure we designed underwent resonant increased cross by four-level fractals. As shown in L1 = 45 μm, L2 = 15 μm, L3 = 7.5 μm, L4 = 3.75 μm, w = 3.6 μm. The length of the three-level fractal is slightly increased to 48.6 μm, which is L1 + w, and the length of the four-level fractal is 48.75 μm, which is L1 + L4. For our design, the Fermi energy of the top layer graphene corresponds to 1 eV.The metamaterial absorber we propose is composed of a fractal graphene pattern layer, an MgFεd = 1.9  and the 2 dielectric layer are consistent with the first layer, as shown in 2 dielectric layer/air interface) at a distance of dt = 12 μm, that is, the distance from the ground is 33 μm in Q1 = 50 μm. The supercell period Q = 100 μm, and the graphene thickness is gt = 0.5 nm.In the bottom layer, the size and arrangement of the cross shape embedded in the MgFThe conductivity of graphene is provided by the Kubo equation, and the Kubo equation determines the intraband and interband transitions by both ,37:(1)σgkB is Boltzmann’s constant, h is the Planck’s constant, T is the Kelvin temperature, ω is frequency of the electromagnetic wave, e is the elementary charge,Here, In the terahertz band, the conductivity of graphene is mainly provided by the intra-band transport of carriers, while the inter-band transport is suppressed. At this time, the above calculation formula for graphene conductivity is simplified as:In addition, electrical conductivity will directly affect the characteristics of surface plasmon polariton (SPP) excitation.It can be seen from formula Equation (5) that the conductivity affects the dielectric constant of the graphene film. Graphene is an ultra-thin film with a certain equivalent dielectric constant:εo is the dielectric constant of the vacuum and g =t 0.5 nm is the thickness of the graphene. The wavelength of electromagnetic waves is much greater than the thickness of graphene, which is a boundary condition that can be used in transition simulation.Therefore, it can be flexibly manipulated using applied voltage, temperature, carrier concentration, etc., which can be obtained by creating subwavelength composite materials, where ns, by the equation:The Fermi energy of graphene mainly depends on the carrier concentration ns is the carrier concentration. Bias voltage and chemical doping can change the carrier concentration, but it is proportional to the bias voltage applied to the graphene layer and εd is the relative permittivity of the dielectric layer, H is the thickness of the dielectric layer. Equation (7) gives a specific conversion relationship:Here The above theory fully demonstrates that the absorbing material applies bias voltage or chemical doping to achieve dynamic adjustment, so as to achieve the purpose of tunable absorption. This process qualitatively changes the frequency of surface plasmon polariton (SPP) excitation characteristics, thereby affecting the absorption the operating frequency of the wave material.In order to evaluate the function of the double-layer graphene terahertz absorber we designed, we performed numerical simulations using the electromagnetic simulation software based on the finite element method. In the simulation, a cell in the periodic structure is taken as the calculation object, the boundary conditions of the periodic cell in the X and Y directions are selected, and the Z direction is set as the open boundary condition.w) formula can be written as:ω) and R(ω) are the transmission coefficient and reflection coefficient, respectively, and the absorptivity is obtained by using simulation software, selecting the frequency domain solver, and deriving the absorptivity and S parameters. It can be seen from Equation (8) that, by reducing the transmission and reflection coefficients, higher absorption spectra can be obtained. The ideal electrical conductor in the simulation software is used as a thin metal film reflective layer ground plane to minimize the transmission coefficient. The result shows that the transmission coefficient of the metal layer is zero, A (ω) = 1 − R(ω).The absorptance A MgF2 dielectric layers of the structure with different thicknesses was studied, and the results are shown in mt = 45 μm and dt = 12 μm. It can be seen from dt does not change significantly between 11–15 μm, but at 0.6–0.9 THz, dt = 12 μm has a good absorption effect, and the bandwidth is relatively large when dt = 12 μm, and we can see dt = 12 μm has the best absorption effect. mt layer, the absorption becomes better and better. Under certain other conditions, when mt = 45 μm, a better absorption bandwidth and high absorption rate can be obtained.In order to better test the performance of our designed absorber, the influence of the absorption spectra of the top and bottom  in the range of 0.55 THz to 1.81 THz, where the center frequency