Graphene is an attractive component for high-performance stimuli-responsive or ‘smart’ materials, shape memory materials, photomechanical actuators, piezoelectric materials and flexible strain sensors. Nanocomposite fibres were produced by electrospinning high molecular weight Polyvinylpyrrolidone (PVP-1300 kDa) in the presence of noncovalently functionalised graphene obtained through tip sonication of graphite alcoholic suspensions in the presence of PVP (10 kDa). Bending instability of electrospun jet appears to progressively increase at low graphene concentrations with the result of greater fibre stretching that leads to lower fibre diameter and possibly conformational changes of PVP. Further increase of graphene content seams having the opposite effect leading to greater fibre diameter and Raman spectra similar to the pure PVP electrospun mats. All this has been interpreted on the basis of currently accepted model for bending instability of electrospun jets. The graphene addition does not lower the very high sound absorption coefficient, α, close to unity, of the electrospun PVP mats in the frequency range 200–800 Hz. The graphene addition affects, in a non-monotonous manner, the bell shaped curves of α versus frequency curves becoming sharper and moving to higher frequency at the lower graphene addition. The opposite is observed when the graphene content is further increased. Recently ,2 the prGraphene is one of the most promising materials because of its large specific surface area, good electrical conductivity, high Young’s modulus and thermal conductivity ,10,11. MElectrospinning allows to prepare very thin polymeric nanofibers down to a few nanometres, ,23,24,25Recently the authors demonstrated  that ele3) were successfully obtained by electrospinning PVP of high molecular weight (1300 KDa), at different graphene concentration. The interest in the addition of graphene comes from the possibility it offers, in combination with other inorganic nanomaterials, to improve flame retardancy [In the present work, light non-woven mats (density = 63 kg/mtardancy  that ofttardancy . For somThe blankets were prepared by electrospinning solutions of PVP of high molecular weight 1300 KDa) in which noncovalently functionalized graphene had been dispersed. It is well known [300 KDa i−1) was proposed [Oxidative debris are produced during the oxidation process . For allproposed . Thanks −1) were suspended in a high molecular weight  PVP solution that was successfully electrospun. The paper shows that graphene addition does not lower the very high sound absorption coefficient α, close to unity, in the frequency range 200–800 Hz, previously reported by the authors [In the present study, these pristine graphene dispersions stabilized with low molecular weight PVP  and Poly(vinyl pyrrolidone) (PVP)  were purchased from Sigma Aldrich .Graphite flakes (CAS Number 7782-42-5), poly(vinyl pyrrolidone) (PVP)  solution in alcohol (10 mg·mL−1). The solution was tip sonicated using a Q500 sonicator (QSonica) with an output power of 150 W for 1 h at room temperature. The dispersions were then centrifuged at ~7000 rpm for 4 h to remove aggregates. It has been demonstrated in the past that this method yields noncovalently functionalized graphene dispersions [Stable graphene dispersions were prepared by adding 40 mg·mLpersions .−1) solutions (15 wt.%) with different graphene concentrations (from 0.03 to 7.68 mg·mL−1) were prepared. In the following the electrospun samples will be distinguished with the acronyms: PVP-G0.03, PVP-G0.12, PVP-G0.48, PVP-G1.92, PVP-G7.68, where the number that follows G is the concentration of graphene in the electrospun solution. The scheme of the electrospinning apparatus is reported in Alcoholic (ethanol) PVP . The applied voltage was 21 kV. Fibres were collected on a grounded metal collector (wrapped with a copper foil) which was 39 cm away from the needle at room temperature and relative humidity 45 ± 10%. The as-prepared electrospun non-woven mats were dried out at 100 °C for 90 min and stored in a desiccator.The solutions were loaded into hypodermic syringes fitted with blunt needles. A syringe pump  was used to control the flow rate of the solution . The 514 nm line of an air-cooled Ar+ laser , was injected into an integrated Olympus microscope and focused to a spot diameter of approximately 3 μm by a 20× objective with a final 4 mW power at the sample. A holographic notch filter was used to reject the excitation laser line. The Raman backscattering was collected using a 0.1 mm slit and a diffraction lattice of 1200 grooves/mm, corresponding to an average spectral resolution of 8 cm−1. Both mats and starting solutions have been investigated. Solutions were left evaporating on Si substrates and it took 60 s to collect a complete data set by a Peltier-cooled 1024 × 128 pixel CCD photon detector (Andor DU401BVI). Raman measurements were at least triplicated for scope of reproducibility. Wavelength calibration was performed by using cyclohexane as a standard.A confocal Raman microscope Jasco, NRS-3100 was used to obtain Raman spectra by Spectra ManagerThe morphological characteristics of the flakes were analysed by atomic force microscopy (AFM) using a microscope Digital Instruments Nanoscope IIIawith WSxM software , equipped with a sharpened silicon tip having an apical curvature radius of 5 nm. The AFM images were acquired in tapping mode under ambient conditions, with a scan size and rate of 2 μm and 1 Hz, respectively. After performing deconvolution on each AFM image, in order to minimize the tip size effect, the three-dimensional view of the deposits was reconstructed and the thickness was evaluated by means of an image processing technique.Scanning Electron Microscopy (SEM), with FEI Inspect and by using Image-Pro Plus , observations, so as reported elsewhere . The staH12 is:rR and iR are respectively real and imaginary part of complex acoustic reflection coefficient (R), k is wave number and it is equal to 2πf/c , L distance from the test sample to the centre of the nearest microphone, s centre-to-centre spacing between microphones and j = √(−1). From Equation (1) it is possible to calculate the sound absorption coefficient at normal incidence as a function of frequency [p0 and c0 respectively density and speed of sound in the air, The sound absorption coefficients were measured through an impedance tube so as reported in the previous paper  accordinrequency ,38 and t−1) so as described in the experimental section with a process recently proposed in the literature [Graphite was exfoliated in the presence of low molecular weight PVP  and the shape of the G′ band in the “NCFG” spectrum indicates a three-layer structure of graphene [The Raman spectra (on excitation with wavelength of 514.5 nm) of graphite, exfoliated graphite  and pure PVP are reported in graphene ,39. The graphene .The electrospun mats were produced in thin layers (about 1 g weight) corresponding to an electrospun solution volume of 8 mL.−1) is detectable only for the highest-graphene content mat, (−1 (−1 frequency is due to both a C-C stretching and to CH2 rocking [−1 in the presence of graphene), much lower than that observed in silver suspension in PVP, where Ag+-induced redshifts are observed ranging from 16 to 27 cm−1 for different PVP molecular weights [ent mat, . Moreovemat, (−1 . Particu rocking , that ar rocking . Therefo weights .In order to explain the results it is worth reminding that, in the electrospinning apparatus, fibres are formed under the action of an electrostatic force. Basically, an electrospinning system, whose scheme is reported in Recently the origin of the instability was explained . Near thAccording to the above description, a possible role of graphene can be proposed so as sketched in a, is defined simply as the ratio of sound energy absorbed to the incident one. It changes with the frequency of the sound wave. The acoustic properties of the samples were measured through the acoustic impedance tube.As it is known sound waves are longitudinal mechanical waves propagating at speeds and frequencies depending on the acoustical properties of the medium. When a sound wave impacts upon the surface of a solid body, some portion of its energy is reflected, some absorbed and the rest transmitted through the body. An absorption coefficient, αIn Bell shaped curves, with very high absorption coefficient at the maximum, were, in all cases, obtained so as reported by the authors for pure PVP in a previous paper . Figure Tip sonication of graphite alcoholic suspensions in the presence of low molecular weight PVP is confirmed effective to produce graphene, with a three layer structure functionalised with low molecular weight PVP.The graphene addition affects in a non-monotonous manner the electrospinning process. Bending instability of electrospun jet appears to increase at low graphene concentration with the result of greater fibre stretching that leads to lower fibre diameter and possibly conformational changes of PVP. Further increase of graphene content seems having the opposite effect leading to greater fibre diameter and Raman spectra similar to the pure PVP electrospun mats. All this appears to be related to the acoustic properties that also vary in a non-monotonous way. It is worth underlining that, at knowledge of the authors, this is the first time such non-monotonous effects on the addition of graphene are described.


The STEADI initiative recommends screening older adults for falls annually using either the 12-item “Stay Independent” or the “three-key questions” screening tools. Both tools ask about falling in the preceding year. However, the comparative predictability of each tool has not been assessed. In response, CDC and NORC, assessed both tools’ ability to predict falls at six and twelve months. Adults 65+ (n=1900), were recruited from a nationally representative panel and were screened for fall risk at baseline using both tools and then followed for a year to determine if they fell. At baseline, 38% of older adults were categorized at-risk of falling based on the 12-item “Stay Independent” and 56% were considered at-risk based on the three-key questions. The history of falling question was excluded for the six month analyses. The “Stay Independent” identified 60% of fallers and the remaining two questions of the three-key questions identified 57% of fallers.


Compared with single-layer graphene, the bandgap will be opened; however, the bandgap will be reduced significantly when compared with single-layer MoS2. Redshifts of the absorption coefficient, refractive index, and the reflectance appear in the GM system; however, blueshift is found for the energy loss spectrum. Electronic structure and optical properties of single-layer graphene and MoS2 are changed after they are combined to form the heterostructure, which broadens the extensive developments of two-dimensional materials.The electronic structure and the optical properties of Graphene/MoS Graphengraphene  and SnO22 is one of the transition metal dichalcogenides (TMDs). MoS2 can appear in two-dimensional or three-dimensional forms. The direct band gap will be about 1.8 eV [2 appears as a single-layer two-dimensional material, which makes it a very good semiconductor material. Monolayers of MoS2 have many excellent properties, such as high electron mobility, low dimensionality, smooth atomic sheet [2 have been successfully prepared due to their extraordinary properties [2 opens up possibilities for many applications. For example, Ma et al. [2, MoTe2, and WS2 monolayers by means of first-principles calculations. In 2011, Chang et al. [2 composites by an L-cysteine-assisted solution-phase methodand the obtained composites showed three-dimensional architecture and excellent electrochemical performances which can act as anode materials for Li-ion batteries. Soon Li et al. [2 nanoparticles on reduced graphene oxide (RGO) sheets and the MoS2/RGO hybrid exhibited superior electrocatalytic activity in the hydrogen evolution reaction. Coleman et al. [2 with suspensions of graphene or polymer solutions. A recent study reported the catalytic activity of MoS2/graphene dots for an oxygen evolution reaction [MoSt 1.8 eV ,22 when ic sheet ,23, and ic sheet . Monolayoperties  and haveoperties ,29,30,31a et al.  systematg et al. ,34 succei et al.  developen et al.  showed treaction . The abo2 is an essential property for many optical applications; so, in this paper, we explore the optical properties of GM based on density functional calculations. The structure of this paper is as follows: There is still a lack of research of optical properties in GM heterostructures up to now. The heterogeneous structure of graphene has bright prospects of applications and the direct bandgap electronic structure of MoS2 monolayer is 3.16Å, and the lattice constant of pure graphene is 2.47Å, so the supercell of MoS2 we used was 4*4*1, and the supercell of graphene was 5*5*1. The lattice mismatch ratio of the system was about 2.29%. We stacked monolayer graphene and monolayer MoS2 to form the heterostructure of GM, which is shown in −4 eV. The Brillouin zone was summed according to the 9×9×1 Monkhorst–Pack characteristic K point. Based on the above conditions, the calculated distance between graphene and MoS2 is 3.64Å. Then, the electronic structure and the optical properties of the heterostructures are calculated. Van der Waals interactions are included in the calculations.The DFT calculations we used are performed by the VASP (Vienna ab-initio Simulation Package) software package ,39. The 1(ω) + iε2(ω) of the heterostructure, which is a function of photon energy. Generally speaking, the dielectric constant is the real part of the complex permittivity, ε1(ω). The dielectric constant is caused by various kinds of displacement polarization inside the material and represents the energy storage term of the material. The imaginary part of the complex permittivity, ε2(ω), is related to the absorption (loss or gain) of the material. The steering polarization can not keep up with the various relaxation polarizations caused by the change of the external high-frequency electric field, and represents the loss term of the material. The formula of ε2(ω) is as follows:The optical properties can be modeled by the dielectric constant of the system. We use the superposition of Lorentz oscillators to model the complex dielectric function ε(ω) = ε1(ω) of the dielectric function can be obtained by using the Kramers–Kroing relation,The real part ε1(ω) and ε2(ω). The formulas are:Other optical constants can also be obtained from the dielectric function. For example, the absorption coefficient α(ω), refractive index n(ω), reflectance R(ω), and energy loss spectrum L(ω) can all be derived by ε2 monolayer, and the GM heterostructure, we first calculate the electronic structures of the three systems. The energy band structures and the electronic density of states (DOS) for the three systems are shown in 2 is a material with a band gap of 1.73 eV. After they are stacked together to form the GM structure, as shown in 2 monolayer, which can be confirmed by the charge transfer between graphene and MoS2 after stacking. 2.In order to illustrate the similarities and the differences of the graphene monolayer, MoS2 (M), and GM heterostructure are shown in 1(ω). We can clearly see from the figure that the overall trends for all systems are almost identical with only small differences. In fact, people are more interested in the changes that occur in the visible light region. In the visible light region, the value of the ε1(ω) is obviously the largest in the GM system, followed by the M system, and finally the G system. Comparing the GM and G system at the low-energy zone, it can be found that the parallel direction of ε1(ω) for the two systems not only changes at the maximum values, but also GM has an obvious blueshift of ε1(ω) relative to the G system. 1(ω) in the vertical direction and we find similar regularity with those of 1(ω) illustrates differences in the vertical and horizontal directions. 1(ω) can be found. The peak value of the dielectric constant of the GM system has been significantly improved compared with G and M and different degrees of redshift or blueshift can also be found.The calculated dielectric constants ε(ω) of the monolayer graphene (G), monolayer MoSThe parallel direction and vertical direction of the refractive index n(ω) are given in The parallel and vertical directions of the reflectance R(ω) are given in The energy loss spectra L(ω) are given in In this article, we mainly discuss the electronic structure and the optical properties of GM heterostructures from the first principles calculations. Based on the DFT theory, dielectric constant, ε(ω) absorption coefficient α(ω), refractive index n(ω), reflectivity R(ω), and energy loss spectrum L(ω) of the systems are calculated. It is found that there is indeed a clear improvement of the optical properties for the GM system comparedto the G and M systems. The band gap and the dielectric constants become large for the GM system and there are redshifts for the absorption coefficient, refractive index, and the reflectance. A blueshift is found for the energy loss spectrum in the GM system. All of the above results show that, due to the formation of the heterojunctions, the optical properties of the GM system have been significantly improved compared with the single layers, which deliversa more effective way to use two-dimensional materials in optical applications.


These unique electronic properties controlled by design, makes Mollecular Pillared Graphene an excellent material for flexible electronics.The structural and electronic properties of molecularly pillared graphene sheets were explored by performing Density Functional based Tight Binding calculations. Several different architectures were generated by varying the density of the pillars, the chemical composition of the organic molecule acting as a pillar and the pillar distribution. Our results show that by changing the pillars density and distribution we can tune the band gap transforming graphene from metallic to semiconducting in a continuous way. In addition, the chemical composition of the pillars affects the band gap in a lesser extent by introducing additional states in the valence or the conduction band and can act as a  Such materials, which can be manufactured in various forms and shapes are expected to contribute significantly to develop modern electronic devices which are used in a variety of applications, such as telecommunications, sensors, imaging, energy conversion and batteries.During the last seven decades there has been a huge growth in the development of new electronic devices, which enabled for the development of new technologies and new markets globally. The discovery of new electronic materials and new methodologies to manipulate them has played a key role for the construction of the electronic parts needed for a chip. Among other materials included in a chip, semiconductors have attracted a lot of attention from the scientific community and the industry and significant efforts have been made to find new semiconducting materials to replace silicon. The basic requirements for the evolution of the silicon based integrated circuits have been the continuous increase in the speed, the minimization of the size and energy consumption and the reduction of the cost. Besides the efforts to improve the performance with respect to the above mentioned factors, there have been a lot of efforts to build electronic devices with better mechanical flexibility, giving rise to an emerging research field of flexible and stretchable electronics2. Reduction of dimensions and designing new flexible architectures give the ability to maintain the desired electronic properties and enhance the mechanical flexibility in the case of inorganic based flexible devices3. Organic based materials hold much of the promises to build flexible electronic devices since they have larger intrinsic flexibility with respect to inorganic based materials and it is easier to integrate them on flexible substrates5. Although significant progress has been made in controlling their electronic properties, their broad applicability suffers from their low chemical stability which increases the overall costs since special care should be considered during integration.Flexible electronic materials is considered as one of the most emergent research areas nowadays since there is a tremendous need to build low cost, large area electronic devices with the ability to be incorporated on flexible substrates. They can be categorized as either inorganic or organic based materials with their own unique properties in terms of intrinsic flexibility, carrier density and carrier mobility. In order to build a flexible device, they must be deposited on flexible substrate, which usually is a polymer like PDMS, using a variety of techniquesThe great challenge in the area of flexible electronics is to overpass the barrier that the combination of the two different faces in the material put, i.e., desirable electronic properties as well as mechanical conformability. From device design perspective, the real novelty will be to design a relatively flexible material with pronounced electronic properties and not to combine two materials with completely different nature -a thin film transistor and a flexible plastic substrate. Such a design will lead to minimizing contact issues  associated with the interface.6. Graphene has a very large surface area 7, has large carrier mobility up to 200,000 cm2V−1s−1 when the carrier density is ~1012 cm−2 9, possess highest value of room temperature electrical conductivity in room temperature (106 S cm−1)10, possess extreme mechanical properties such as the Young modulus (~1 TPa)11 and tensile strength (~42 Nm−1)11, and is known to be one of the best thermal conductors 16 along in-plane direction. Its possible applications have triggered numerous studies over the past decade on how these properties are modified when doping and functionalization take place to the nanoscale.Among potential flexible alternatives to conventional electronics, different nanocarbon polymorphs, such as graphene, carbon nanotubes, carbon nanofibers, and nanographite have been a subject of special interest for the last decade. In particular, graphene, the ultimate two-dimensional material possesses fascinating electronic, mechanical, and thermal propertiesOne key feature which has limited graphene usage in nanoelectronics is the observation that it is a zero band gap material with the characteristic Dirac cones observed in the band structure. Graphene applications in electronics can be further expanded if graphene be efficiently converted to a semiconductor without great loss of aforementioned properties. It would be desirable to be able to tune its electronic properties in a controllable way by either tailoring its structure in the atomistic level or by applying external stimuli . Structure modifications in graphene has been applied in sever always including the introduction of vacancy defects with varying sizes, the substitution of carbon atoms with heteroatoms, the construction of graphene nanoribbons with certain size, shape and chemical functionality on the edges, and the chemical functionalization of the basal plane of the graphene flakes. It has been shown that such modifications can effectively adjust the electronic properties of the corresponding materials.18. Pillared graphene, recently proposed by our group19, is such a nano-architecture, where carbon nanotubes are incorporated between graphene flakes to form a 3D carbon based porous nanostructure. Such nanostructures possess notable hydrogen storage, gas separation, electronic, thermal, and mechanical properties24 which could be tuned by tailoring the structure. Such interconnected graphene is still expected to be semi-metallic due to overwhelmingly large sp2 nature of carbon atoms, providing extended electronic cloud.Based on graphene structure and the large number of existing routes towards its chemical functionalization, novel 3D graphene architectures can be designed by incorporating various types of nano-constituents in between graphene layers. The incorporated spacers can keep the layers apart either by forming van der Waals heterostructures or by forming heterostructures through the formation of chemical bonds between the spacer and the 2D layersmolecular pillaring) disrupt electron resonance in out-of-plane direction and can be used as a knob to tune the electronic behavior of graphene  while providing the unique structural properties of a flexible material with the endless variety of pillaring organic molecules. In addition to tuning electronic behavior, molecular pillared graphene (MPG)  Fig.  can be c40. In the virtual space of the thousands of MOF structures, whole families have been created sharing the same topology and altering the organic molecule acting as building bridge (linker). Similarly, in the graphene case, the number of organic molecules that can be used for pillaring graphene layers is virtually almost endless! Combining this with the variety of intramolecular lengths of the organic molecules and grafting patterns in graphene end up in a large family of novel 3-D architectures entitled as Molecular Pillared Graphene (MPG).A similar strategy in materials science was successfully applied in Metal-Organic Frameworks (MOFs)ab-initio calculations with such large number of atoms are extremely computationally demanding. Within DFTB framework, band gaps for all structures were calculated and the corresponding density of states (DOS) diagrams were analyzed to provide further insights into the origin of the states at the edges of the valence and conduction bands around the band gap. Such an analysis allowed us to systematically and quantitatively verify the effect of the pillared molecules and pattern on the electronic properties of each MPG structure. Moreover we examined the effect of the relative distribution of the molecular pillars on the band gap of these materials. Details for DFTB method and the corresponding calculations can be found in Methods section.In order to explore the properties of MPGs in the present study, we designed fifteen novel flexible 3D graphene network structures. They were assembled by combining three different pillar densities with five highly aromatic molecules of different size and aromaticity. The structural and electronic properties of these 15 MPGs were examined by performing electronic structure calculations under the Tight Binding Density Functional Theory (TB-DFT) approximation. For electronic structure calculations, such an approximation at semi-classical level is necessary as full 14 and Covalent-Organic Framework (COF) materials41. The rings are formed from the condensation reaction of the boronic acids of the organic pillars with the oxygen species on the basal plane of the oxidized graphene and include the bonding of a neighboring pair of carbon atoms of the graphene with the corresponding oxygen atoms of the boronic acid. The molecular supercells are consisted of two graphene layers with adjusted size depending on the pillar density and the length of the pillaring molecule. Initially, the pillars were orderly dispersed over the two interlayer spaces that are formed. Periodic boundary conditions were applied to transform the molecular model to the corresponding periodic structure  and the second was the choice of the organic molecule which acted as the pillar. Three pillar densities were taken into account in the construction of the molecular models denoted as 1/8, 1/18 and 1/32. 1/8 corresponds to the densest packing of pillars considered in this study with one pillar per eight carbon atoms belonging to the graphene layers of the model. The difference in the pillar density can be easily seen in periodic models presented in Fig. ure Fig. .Figure 2The initial MPG periodic structures were constructed based on a hexagonal lattice . In most cases, the features of the hexagonal lattice were retained with negligible distortions after structure and lattice optimization. The largest distortions (approximately ± 6°) were found for the case of the naphthalene acting as the pillar between graphene layers, independent of the density of the pillars in the structure. These distortions were attributed to the distortions occurred on the boronic ring due to the slight non-linearity of the naphthalene pillar. In Fig. The flexibility of the MPG’s was estimated by calculating the bulk and the shear modulus. We found that MPG’s flexibility is much larger than other materials such as bulk silicon or graphene. It becomes larger by increasing the length of the pillar or by decreasing the amount of pillars per C atoms of the graphene layers in the cell (see Supplementary Information).The effect of structural variation on the electronic properties of the initially designed MPGs was examined by performing calculations with the SCC-DFTB methodology as detailed in Methods section. Figure 3 hybridized carbon atoms resulting from the formation of the boronic rings. Fewer pillars (low pillar density) lead to fewer sp3 hybridized carbon atoms and a smaller disruption of the semi-metallic properties of the graphene, where larger number of pillars will partially destroy the graphene electronic properties and lead to semiconducting behavior. For the lowest pillar density (MPG_1/32), the band gap for the corresponding structures was found to be 0.98 eV with a small variation for the case of the pyrene derivative (MPG_1/32_pyrene) for which the value of 0.71 eV was calculated. For the intermediate pillar density of 1/18, the band gap was found to be at 0.14 eV.For the three pillar densities that were considered here for the MPG structures designed initially, we found that the band gap decreases by decreasing the pillar density (less pillars per graphene surface area). The reduction in the band gap happens with a fluctuation for the intermediate pillar density (1/18) which is caused by the non isotropic relative distribution of the pillars belonging to the adjacent interlayer spaces which can be considered in the periodic structures. The semiconducting behavior can be attributed to the disruption of the extended π-system of graphene layer in all directions due to the presence of spThe effect of the chemical composition of the pillars on the band gap values was found to be less profound than the pillar density, especially for the cases corresponding to the 1/18 and 1/32 pillar densities. The difference can be easily observed when comparing the band gap values as a function of the chemical composition for 1/8 and 1/18 pillar densities in Fig. For the most interesting 1/8 pillar density, we plotted the band gap with respect of the C-atoms per pillaring molecule Fig. . Two difThe influence of the atoms belonging either to the pillar or the graphene layer on the electronic properties of the MPG structures was further explored by plotting the total density of states (DOS) and the partial density of states (PDOS) for all structures in this study. Here, we are mainly interested in locating the contributions of the carbon, boron, and oxygen atoms of the structures at the states near the bottom of the conduction band and the top of the valence band. Hydrogen has been excluded from the plots since it is expected to have no contributions on the area of DOS plots that we are interested in. Also the s type atomic states of the carbon, boron and oxygen have no contribution to the valence or the conduction band, as expected, and thus are not considered here.From the examination of the DOS plots for the initial MPG structures, we arrived at two general conclusions: (a) The main contributions in the states around the Fermi energy come from the p-type states of the carbon atoms, with smaller or negligible contributions from p-type states of the oxygen or the boron atoms Fig.  the origIn order to further investigate the origin of the band gap variation we performed analogous calculations to single graphene layers functionalized similarly with the pillared structures. We used phenyl and pyrene derivatives of the corresponding MPG structures to build the functionalized monolayers , we found band gap values ranging from 1.39 eV to gapless for the case of 1/18 pillar density, where for 1/32 density, the variation was found to be from 0.98 eV to gapless.We have examined a set of molecularly pillared graphene networks by varying both the pillar density and the chemical composition of the pillar molecule in terms of electronic properties by performing TB-DFT calculations. Our results show that by changing the pillar density, we can tune the band gap transforming graphene from metallic to semiconducting in a controlled manner. For the highest pillar density, the chemical composition of the pillars also affects the band gap by introducing p-states in the valence band, where this happens to a lesser extent for the other two lower pillar densities. We also showed that the distribution (isotropic or not) of the pillars can induce a variation in the band gap, transforming MPG materials from semiconducting to conducting. The key advantages of these materials compared to a functionalized single graphene layer are the additional mechanical stability of MPG’s due to the linking of the graphene layers by pillars, the engineering of the graphene layer relative position and the corresponding interspace. We believe that this unique way of tuning electronic properties, controlled by design, makes the proposed organically linked graphene 3D nanostructures an excellent alternative for flexible electronics. Considering the thousands of organic linkers that can be used for pillaring graphene, we have presented this study as a ‘proof of principle’ and expect that this study will pave the way for a novel large family of flexible electronic materials.42 forcefield was used along with the conjugate gradient (CG) algorithm for the optimization in the P1 symmetry. These calculations were done with the GULP43 code. Then, periodic optimization (both atom positions and lattice vectors) were carried out by using Self-Consistent-Charge Density-Functional-Based Tight-Binding (SCC-DFTB)46 method. This method is based on a second order expansion of the Kohn-Sham total energy in DFT with respect to charge density fluctuations and is capable of maintaining all the qualities of DFT without extensive empirical parametrization. Periodic boundary conditions were used to represent the crystalline solid state of the MPG structures. The conjugate gradient method was used for the geometry optimization, where the atomic force tolerance was set to 3∙10−4 eV/Å. No symmetry constrains were imposed during optimization. The number of k-points needed for the calculations were determined by reaching convergence of the total energy as a function of the k-points according to the scheme proposed by Monkhorst and Pack47. A 4 × 4 × 4 grid proved to be sufficient for sampling the Brillouin zone for all the periodic structures that were studied here. The necessary integrals together with other atomic and diatomic parameters for building the DFTB Hamiltonian were taken from matsci-0-3 Slater-Koster files48, which were downloaded from DFTB.org. matsci-0-350 contain atomic parameters for the B and O atoms which were originally developed in order to correctly describe the structural and electronic properties of similar 2D COF materials37.The atomic positions and the lattice vectors of all MPG periodic structures were preoptimized by performing molecular mechanics calculations. The UFF−5 eV. In the DOS diagrams, the Fermi level on the horizontal axis was shifted to zero. Structure optimization and calculations of the electronic properties were performed with DFTB+ v1.2 and DFTB+ v17.1 codes respectively51.The electronic properties of the designed pillared graphenes were explored by calculating the total density of states , partial density of states (PDOS), and the band structure diagrams for the optimized periodic structures. For the k-point sampling, a 4 × 4 × 4 Monkhorst-Pack scheme was used and the Self-Consistent-Charge tolerance was set to 1∙10suporting Information


Programmed cell death ligand 1 (PD-L1) has already been detected in various carcinomas. In non-Hodgkin lymphoma (NHL), however, the prognostic value of PD-L1 overexpression remains unclear.A meta-analysis of 2321 NHL patients from 12 studies was performed. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the correlation between PD-L1 overexpression and prognosis of NHL, and odds ratios (ORs) with 95% CIs were used to assess the association of PD-L1 overexpression with clinicopathological factors.P = 0.137). Nevertheless, the results indicated that PD-L1 overexpression was associated with poor prognosis in the subtype of diffuse large B cell lymphoma (DLBCL) . We also performed subgroup analyses and meta-regression. The pooled OR showed that PD-L1 overexpression was associated with B symptoms, higher international prognostic index (IPI) score  and Ann Arbor Stages III and IV.The results showed that no significant difference between PD-L1 positive and negative groups was detected in NHL (HR: 1.40, 95% CI: 0.90–2.19; The meta-analysis demonstrated that PD-L1 expression was not associated with prognosis of NHL but was associated with prognosis of DLBCL. Non-Hodgkin lymphoma (NHL), accounting for approximately 90% of lymphomas and comprising various subtypes, is a common hematological tumor. NHL is characterized by a series of malignant DNA repair obstacle events and activating proto-oncogene caused by viral or bacterial infection, immune dysfunction and genetic factors, resulting in a wide range of histological appearances and clinical features at presentation, including painless lymphadenopathy, B symptoms , and so on , 3. TherProgrammed cell death ligand 1 (PD-L1), a 40 kDa type 1 transmembrane protein, can activate B, T cells, macrophages, and dendritic cells . It was Cumulative studies showed that PD-L1 or PD-1 could be used to determine prognosis in various cancers, such as melanoma, non-small cell lung cancer, kidney cancer , and claOur meta-analysis was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement .Four databases—PubMed, Cochrane Library, Web of Science, and Embase—were used to retrieve articles that investigated the prognostic value of PD-L1 overexpression in NHL. Additionally, we used the following terms for searches: “PD-L1,” “B7-H1,” “CD274,” “programmed cell death ligand 1,” “lymphoma,” “non-Hodgkin lymphoma,” “NHL,” “prognosis,” and “survival.” Articles published before January 2019 were included in the meta-analysis. We also performed a reference search.Two independent reviewers evaluated all potential articles. All candidate articles had to meet the following criteria: (1) patients’ NHL diagnoses were histologically confirmed; (2) PD-L1 expression in lymphoid tissue was detected using immunohistochemistry (IHC); (3) hazard ratios (HRs) and 95% confidence intervals (CIs) could be directly obtained from the studies or calculated using data from the articles; and (4) the studies were full-text and written in English. Moreover, any disputes were solved via discussion.Two investigators independently extracted the data from articles. We extracted the following data: first author’s name, study country, publication year, subtype, sample size, cut-off value of PD-L1, HRs and 95% CIs for OS, PD-L1 positive number, follow-up period, treatment, Ann Arbor Stage and IHC antibodies. Furthermore, we contacted the author for original data if we were unable to calculate the effect size through the methods provided by Tierney . We asse2 > 50% was considered significant. If heterogeneity was significant, we chose a random effect model to compute the pooled HR; otherwise, we selected a fixed effect model. Additionally, sensitivity analysis was used to assess the robustness of the pooled results, and publication bias was evaluated using Begg’s test. Subgroup analyses and meta-regression were performed due to significant heterogeneity. All the analyses were performed by STATA 12.0 software  and Revman 5.3 .HRs with 95% CIs were used to evaluate the correlation between PD-L1 overexpression and prognosis of NHL, and odds ratios (ORs) with 95% CIs were used to assess the association of PD-L1 overexpression with clinicopathological factors. Heterogeneity tests were performed using the I-squared statistics, and an IThe literature screening process is illustrated in Fig. All characteristics of the studies are displayed in Table P = 0.137) for OS. The result indicated that PD-L1 overexpression was not associated with NHL prognosis. Significant heterogeneity, however, existed among the selected studies  with I2 = 47.2% , stage III and IV  and international prognostic index (IPI) score of 3 to 5 points . However, there was no significant difference in the subgroups of gender and age  in China, 1.99  in Japan, and 0.47  in Korea. In addition, when cut-off value ≥30%, HR was 2.54  with I2 = 37% , treatment (P = 0.229), location (P = 0.107), tumor type (P = 0.916), and cut-off value (P = 0.058) did not contribute to the heterogeneity.Furthermore, meta-regression was performed for the source of heterogeneity in NHL. The results showed that sample size (P = 0.880) nor DLBCL (P = 0.920).Begg’s test was used to assess the publication bias, which revealed no publication bias for either NHL (P = 0.137) was calculated for 2321 patients from 12 studies, potentially indicating no significant correlation between PD-L1 and NHL prognosis. Nevertheless, the result suggested that PD-L1 overexpression was associated with poor prognosis in DLBCL patients. Figure This is a meta-analysis designed to investigate the relationship between PD-L1 overexpression and the prognosis of NHL. The association of PD-L1 overexpression with some clinicopathological factors was also evaluated. The pooled HR of 1.40 (95% CI: 0.90–2.19; Subgroup analysis and meta-regression showed no contribution to the heterogeneity in NHL. However, perhaps some problems contributed to the heterogeneity. Although IHC was used to detect PD-L1 protein in tumor cells in all studies, different studies adopted different procedures , antibodThe response to treatment is also not associated with the level of PD-L1 expression. Currently, PD-1 blockades are mostly employed clinically. Some clinical trials , 40 showNevertheless, recent studies have uncovered the concrete functional mechanism of PD-L1 in DLBCL. PD-L1, bound to PD-1, caused phosphorylation of AKT, which urge m-TOR to activate its downstream molecules, such as P43-BP1 and P-P70S6K, finally resulting in proliferation and progression of malignant cells , 44, 45.’s due to our having included three more studies than they did. We also adopted two tools to conduct meta-analysis and did sub-analysis.To the best of our knowledge, Zhao et al.  performeSeveral limitations, however, must be considered in interpreting our findings. First, the total sample size of the included studies was small. Second, other clinicopathological factors—such as EBV infection, tumor size, and central neutral system invasion—were not included in the analysis due to insufficient materials. Third, although we performed subgroup analysis by cut-off value, we did not know the best cut-off value for stratification of NHL patients in clinical management.In conclusion, our pooled results showed that overexpression of PD-L1 was not associated with OS in NHL patients; rather, it was associated with the subtype of DLBCL, indicating that PD-L1 could perhaps predict the prognosis of DLBCL. Furthermore, PD-L1 overexpression was associated with the clinicopathological factors of B symptoms, IPI score, and Ann Arbor Stage. Nevertheless, studies on other specific NHL subtypes using standardized immunological tests are needed to further explore the relationship between PD-L1 overexpression and prognosis of NHL.


In this study, we firstly report a novel and facile one-step process using template-directed chemical vapor deposition (CVD) to fabricate highly nitrogen doped three-dimensional (3D) N-doped carbon nanotubes/N-doped graphene architecture (N-CNTs/N-graphene). We used nickel foam as substrate, melamine as a single source for both carbon and nitrogen, respectively. The morphology and microstructure were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, isothermal analyses, X-ray photoelectron microscopy and Raman spectra. The obtained 3D N-CNTs/N-graphene exhibits high graphitization, a regular 3D structure and excellent nitrogen doping and good mesoporosity. Graphenstrength ,9,10,11.strength , supercastrength  and nanostrength . Neverthstrength . Consequstrength . 3D carbstrength ,17,18,19strength , supercastrength  and enerstrength .3 atmosphere and approaches based on different templates. Among them, CVD is the wide method for the synthesis of N-doped carbon nanotube and graphene, which use flammable organic gases  or toxic organic solvent  and pyridine or NH3 as carbon source and nitrogen source, respectively. And the nitrogen N-doped hybrids are always fabricated by a multistep CVD route [4 and C2H2 as carbon source to synthesize carbon nanotubes/graphene hybrid [To improve the electrical and chemical properties, various strategies have been attempted by scientists. One of the effective approaches is introducing heteroatom doping, for example, boron, sulfur, phosphorus and nitrogen ,24,25. NVD route ,29,30,31e hybrid . Moreovee hybrid . Dong ete hybrid ,29. Wange hybrid ,30. SamaIn this study, we reported, for the first time, one-step CVD method to synthesize three-dimensional nanostructure consisting of N-doped carbon nanotubes/N-doped graphene (N-CNTs/N-graphene) can be grown on a nickel foam substrate using low-cost material melamine as a single source for both carbon and nitrogen, respectively. In this contribution, nickel foam, a three-dimensional interconnected structure, not only acts as a porous 3D scaffold for generating graphene and carbon nanotube but also simultaneously provides situ generated Ni nanoparticles (Ni NPs) which facilitate the nucleation and growth of N-doped carbon nanotubes (N-CNTs) on the surface of the N-doped graphene (N-graphene) without requiring any other synthetical catalyst. Our process enables the synergistic use of hydrogen to remove the impurities on the surface of nickel foam, boost the growth of graphene and carbon nanotubes by etching layered carbon nitride which was produced from melamine pyrolysis.2 and successively dispersed in acetic acid solution and ethanol solution by ultrasound for 10 min to clean their surfaces and remove the thin surface oxide layer. Subsequently, the NF was dried under nitrogen (99.99%) atmosphere. The NF thus obtained and melamine was mixed according to the mass ratio (1:5) and the above mixture was then placed in a horizontal quartz tube with outer diameter of 30 mm and inner diameter of 22 mm. Before the CVD reactor (2 (99.99%) was introduced for about 20 min at a flow of 70 sccm. When the center of the furnace reached a temperature of about 800 °C, the sample was annealed for 0.5 h at this temperature under a mixed gas (the flow rate of Ar and H2 is 5:1) atmosphere. After that, the mixture was cooled to room temperature in Ar atmosphere at a flow of 30 sccm and the products were taken out of the quartz tube. Finally, the black product was placed in a 3M HCl solution at 80 °C for two days to fully remove the nickel foam yielding the desired 3D N-CNTs/N-graphene. Furthermore, to obtain uniform N-CNTs growth in this study, we carried out experiments by using different mass ratio between NF and melamine  as shown in Nickel foam (NF) were first cut into pieces of 10 × 10 mm reactor a was heaThe elemental analysis and crystalline degree of the prepared products was characterized with X-ray diffraction . Field-emission scanning electron microscopy  and transmission electron microscopy  was used to observe the morphologies and whole structure of the product. The surface-to-volume ratio of material and pore structures were measured using nitrogen adsorption and desorption isotherms by a Quanta Chrome adsorption instrument . X-ray photoelectron spectroscopy analyses  and Raman spectroscopy  was used to analyze the product.3 [3 which enables the growth of CNTs [2 about 800 °C. Simultaneously, carbon nanotube grows on the surface of graphene layers catalyzed by the Ni nanoparticles produced by etching process of NH3 resulting from decomposing of melamine. In addition, it can be observed that the growth process of CNTs is based on a “tip growth” mechanism [The whole synthetic process of 3D N-CNTs/N-graphene involves one-step CVD in the solid-state pyrolysis of melamine at 800 °C as shown in 3 . Between of CNTs . There aechanism  shown beechanism . Therefoechanism . The oneechanism .The structure and morphology of N-CNTs/N-graphene can be observed by field-emission scanning electron microscopy (SEM). 3. This corresponds to the “tip growth” mechanism. In this mechanism, with the temperature increasing, carbon atoms continue to diffuse to the surface of metal catalyst. Subsequently, when the carbon atoms are saturated, they precipitate from the bottom of the metal particles with the structure of N-CNTs. As shown in To further confirm the whole structure of N-CNTs/N-graphene, we try to observe the material from different view. In order to further observe the internal structure of the 3D N-CNTs/N-graphene material, TEM and HRTEM images are provided to confirm the N-CNTs and N-graphene. As shown in the low-magnification TEM image of −1, 1580 cm−1 and 2700 cm−1 respectively are similar to those Raman peaks of N-doped graphene sheets by CVD method previously reported by Qu et al. [−1 corresponds to the D band of graphitic carbon, which is associated with the number of defects in the crystalline structure of the carbon nanotube and graphene layers [−1 is G peak, which is originated from the E2g vibrational of the sp2-bonded carbon atoms. The intensity ratio of ID/IG indicate the defects in the graphene structure and degree of graphitization. The Raman spectrum also reveals a weak 2D peak located at 2700 cm−1 with a I2D/IG of 0.23, confirming the N-doped graphene sheet is multilayer, which is consistent with the result shown in 2D/IG) of N-CNTs/N-graphene is smaller than that of N-graphene, which is corresponding to the presence of N-CNTs. Moreover, the intensity ratio (ID/IG) of N-CNTs/N-graphene is 0.85, which is higher than the intensity ratio (ID/IG = 0.56) of graphene due to the high-level defects from N-doping. Compared to the N-doped CNTs/graphene hybrids (ID/IG = 0.8) fabricated by Yan et al., our 3D hybrids (ID/IG = 0.85) include more defects induced by highly nitrogen doping and possess higher atomic ratio of nitrogen [To further investigate the characteristics of 3D N-CNTs/N-graphene on the surface of NF, we use the X-ray diffraction to demonstrate the elemental analysis and crystalline degree shown in u et al. .The peake layers . The peanitrogen . These u0 from 0.53 to 0.94 and it belongs to the typical IV curve [2/g which is higher than that of the N-doped graphene (the specific surface area is 6 m2/g) via thermal annealing graphite oxide with melamine and the N-doped nanotube (the specific surface area is 68 m2/g) using melamine as nitrogen source in the previous report, indicating the CNTs within N-CNTs/N-graphene could effectively connect with graphene to integrate the 3D hybrids and enhance dispersion of tubes and graphene sheets [3/g and NF is 0.13 cm3/g, the increased pore volume is mainly due to the N-CNTs and N-graphene grown on the surface of NF. Pore size distribution curve is utilized by using Barrett-Joyner-Halenda (BJH) to further identify the mesoporous structure of N-CNTs/N-graphene. 2 desorption peaks mainly spanned from 2 nm to 50 nm but are narrowly distributed around 4nm and 25 nm in the hybrids, which is in good agreement with similar nitrogen-rich carbon nanotube-graphene hybrids in the previous report by Ding et al. [The Brunauer-Emment-Teller (BET) specific surface areas of N-CNTs/N-graphene and NF are measured from the nitrogen adsorption and desorption isotherms in IV curve , which ue sheets ,41. The g et al. .X-ray photoelectron spectroscopy (XPS) is used to investigate the elemental composition and the structure of N-CNTs/N-graphene. C 1s peak located at about 284 eV, N 1s peak at about 399.8 eV and O 1s peak at about 531.3 eV can be obtained on the full peak of X-ray photoelectron spectroscopy e. RemarkIn summary, we have reported a facile one-step CVD technique approach to fabricate 3D N-CNTs/N-graphene nanomaterial using low-cost industrial melamine as a single carbon and nitrogen source. The N-CNTs/N-graphene are synthesized from one-dimensional N-doped carbon nanotubes and two-dimensional N-doped graphene which grown on the surface of nickel foam possessing interconnected porous 3D structure at 800 °C. The one-dimensional N-doped carbon nanotubes densely distribute on the surface of two-dimensional graphene sheet. The graphene sheet serves as supports of N-doped CNTs and Ni nanoparticles, which lead to nucleation and growth of CNTs and the CNTs in turn prevent the graphene sheets from aggregating. The results also show that defects appear in the wall of CNTs and graphene sheets, which means the successful nitrogen doping process of N-CNTs/N-graphene in the one-step CVD process. Remarkably, the atomic percent of nitrogen is up to 12.7%, which is higher than that of the previous reports on similar materials. And pyridinic-N is the main bonding configurations of nitrogen atoms in the 3D hybrids. The doped nitrogen induces more defects and active sites on the surface of carbon framework but also effectively improves the electronic properties and surface wettability. As a result, the N-CNTs/N-graphene nano-architecture may be suitable for many energy-conversion and energy-storage materials, for example, Li-ion secondary batteries, supercapacitors and Li-S batteries.


P = 0.007). Similarly, PD-L1 high expression was significantly negatively correlated with pCR rate . On multivariate analysis, IDO1 expression was an independent prognostic factor for developing recurrences. Stratification analysis revealed that patients with co-expression of IDO1 and PD-L1 were significantly associated with a lower pCR rate and worse recurrence-free survival than those with one or none positive protein. In conclusion, IDO1 and PD-L1 co-expression could predict poor pathologic response and high risk of recurrence in ESCC after neoadjuvant CRT, indicating a subset of patients who may benefit from CRT combined with immunotherapy.This study aimed to investigate the impact of indoleamine 2,3-dioxygenase 1 (IDO1) expression, programmed cell death-ligand 1 (PD-L1) expression, CD8+ tumor-infiltrating lymphocyte (TIL) status, and their combination on pathologic complete response (pCR) and recurrence in esophageal squamous cell carcinoma (ESCC) treated with neoadjuvant chemoradiotherapy (CRT). Indoleamine 2,3-dioxygenase 1, PD-L1, and CD8+ TIL statuses were evaluated by immunohistochemical analysis on pre-CRT biopsies of 158 patients. Sixty-eight patients (43.0%) achieved pCR after neoadjuvant CRT and 48 patients (30.4%) developed recurrences after surgery. IDO1 and PD-L1 proteins were co-expressed in 28 patients (17.7%). Indoleamine 2,3-dioxygenase 1 positive patients showed a significantly lower pCR rate than IDO1 negative patients (28.6% vs. 51.0%,  Esophageal cancer (EC) is a significant heath burden worldwide, with an estimated 572,034 new cases and 508,585 deaths each year . For locImmunotherapy has rapidly emerged as a novel treatment option and has changed the landscape of therapy for many types of malignancy, including EC . ProgramAs a rate-limiting enzyme in the metabolism of essential amino acid tryptophan in the peripheral tissue, indoleamine 2,3-dioxygenase 1 (IDO1) is another promising target for cancer therapy . With imPrevious studies have revealed that immune checkpoints such as IDO1 and PD-L1 are overexpressed in EC, which are associated with poor clinical outcomes in patients receiving surgery alone ,19,20. HPatient and treatment characteristics of 158 ESCC patients who met inclusion criteria are summarized in P < 0.001, P = 0.005, The mRNA expression levels of IDO1 and PD-L1 were examined by quantitative reverse transcription polymerase chain reaction (PCR) in 20 frozen ESCC tissues and matched normal epithelium. As expected, tumor tissues expressed significantly higher levels of IDO1 than normal mucosa (P = 0.003).According to IHC staining, IDO1 and PD-L1 proteins were positively expressed in 56 (35.4%) and 55 (34.8%) patients, respectively. The median CD8 density was 18  in the whole cohort, and 80 (50.6%) patients were classified as CD8 high density group. Representative IDO1, PD-L1, and CD8 staining patterns are shown in P = 0.007; P = 0.004; P = 0.075; P = 0.032; PD-L1: odds ratio 2.425, P = 0.017).We identified patient and treatment characteristics associated with pCR . IDO1 poAt the time of analysis, the median follow-up time for survivors was 40.2 months . A total of 45 patients (28.5%) had died and 48 (30.4%) developed recurrences during follow-up. Sixteen patients (10.1%) developed locoregional failure only, 25 (15.8%) had distant failure only, and 7 (4.4%) experienced concomitant locoregional and distant recurrences. The 3-year overall survival (OS) rate and 3-year recurrence-free survival (RFS) rate for the whole cohort were 72.1% and 72.3%, respectively.P < 0.001), and PD-L1 positivity was also correlated with recurrence risk . Comparing with IDO1 negativity, IDO1 positivity was significantly associated with worse OS and RFS .Of the 158 patients, 28 (17.7%) were IDO (+)/PD-L1 (+), 28 (17.7%) were IDO (+)/PD-L1 (−), 27 (17.1%) were IDO (−)/PD-L1 (+), and 75 (47.5%) were IDO (−)/PD-L1 (−). Considering the positive correlation between IDO1 and PD-L1 expression, we divided patients into 3 immune subtypes: IDO (+)/PD-L1 (+), IDO (+)/PD-L1 (−) or IDO (−)/PD-L1 (+), and IDO (−)/PD-L1 (−), with corresponding pCR rates of 21.4%, 34.5%, and 57.3%, respectively -γ and tumor growth factor (TGF)-β in lung adenocarcinoma, leading to an evasion of host immune responses . AccordiGrowing evidences have documented the synergism between immunotherapy and radiotherapy ,31. ThroThis study has several limitations. First, the results may be influenced by the selection bias due to its retrospective nature from a single institution; thus, validation should be performed by prospective studies as well as external cohorts. Second, the expression of immune checkpoints was evaluated from small samples obtained by endoscopic biopsy, thus we cannot differentiate the central tumor from the invasion front. Third, we performed IDO1 IHC assay using a single monoclonal antibody. Since no guidelines for antibody use or quantifying IDO1 expression in ESCC have been defined in the literature, the reproducibility of our results should be validated in future.All ESCC patients who received neoadjuvant CRT followed by surgery from the prospectively maintained database at our institution between January 2003 and December 2016 were retrospectively analyzed. The eligibility criteria included: pre-CRT biopsy obtained, pathologic confirmation of stage II-III ESCC according to the 7th TNM staging system of the American Joint Committee on Cancer, and completion of neoadjuvant CRT followed by esophagectomy with curative intent. This study was approved by the Ethics Committee of Sun Yat-sen University Cancer Center (No. B2019-010-01) and informed consent was waived due to its retrospective nature.All patients received external-beam radiation using three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT). The typical prescribed dose was 40.0–45.0 Gy with a daily fraction of 1.8–2.0 Gy. All patients received concurrent platinum-based chemotherapy during radiation and esophagectomy was performed approximately 6 to 8 weeks after the completion of CRT. The pCR was defined as no viable cancer cells in all layers of the esophagus and in the lymph nodes resected. After surgery, patients were followed every 3 months during the first year, then every 6 months for the next 2 years, and thereafter annually. The first recurrence pattern was recorded to classify locoregional or distant recurrence, which was established on histologic, cytologic, or explicit radiologic proof.−ΔΔCT method and GAPDH was used for normalization. Each experiment was repeated at least three times in triplicate. The primer sequences used in real-time PCR were as follows: IDO1 , PD-L1 , and GAPDH .Total RNA from primary ESCC tissues and the adjacent normal tissues obtained from the same patient was extracted using TRIzol reagent  according to the manufacturer’s protocol. Then, reverse transcription of total RNA was performed to synthesize cDNA, which was amplified and quantified by SYBR-Green in CFX96 Real Time System C1000 Cycler . Relative quantification of gene expression levels were analyzed by the 2Formalin-fixed and paraffin-embedded tumor tissues were cut into 4-µm-thick sections for immunohistochemical (IHC) analysis. After deparaffinization, antigen was retrieved by citric acid buffer (pH 6.0) using a steamer autoclave, then incubated with anti-IDO1 antibody  at 1:1000 dilution, anti-PD-L1 antibody  at 1:250 dilution, and anti-CD8 antibody  at 1:500 dilution overnight at 4 °C. Subsequently, the sections were incubated with a secondary antibody, stained with diaminobenzidine, and then counterstained with hematoxylin, dehydrated, and coverslipped.All IHC analyses were evaluated by two experienced pathologists (Y.L. and S.L.) who were unaware of patient clinical information. Expression of IDO1 in tumor tissues were considered positive if tumor cytoplasmic and membrane staining >50% regardless of intensity. For PD-L1 staining, >1% tumor membranous staining was considered positive and PD-L1 expression on tumor-infiltrating immune cells was not scored. The quantitative density of CD8+ TILs was evaluated within 5 stromal areas of the tumor under high-power magnification of 400× for each patient. The average number of CD8+ TILs per high power field was counted and the median number of CD8+ TILs was determined as the cut-off point for CD8 density.P ≤ 0.1 in the univariate analysis were subjected to the multivariate analysis. Statistical analyses were performed using SPSS 22.0 software . P < 0.05 was considered statistically significant.Associations between IDO1 and PD-L1 expression, CD8+ TIL status, and patient clinicopathologic features were examined using the chi-square or Fisher’s exact tests. Follow-up and survival times were defined from the date of surgery until event or censor. Kaplan-Meier method was used to estimate OS and RFS. Log-rank test was used to examine intergroup differences, and Cox proportional hazards regression model was used to analyze prognostic factors for disease recurrence (backward stepwise). Univariate and multivariate logistic regression models were performed to analyze possible predictors of pCR. Variables with Indoleamine 2,3-dioxygenase 1 and PD-L1 co-expression could predict poor pathologic response and high risk of recurrence in ESCC after neoadjuvant CRT, indicating a subset of patients who may benefit from CRT combined with immunotherapy. Future prospective studies are warranted to confirm its role as a predictive biomarker for pCR as well as an indicator for the selection of immunotherapy regimens.


Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density polyethylene (LDPE). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images were employed to observe the dispersion of graphene with a two-dimensional structure in LDPE. The time-dependent space charge dynamic behaviors of graphene/LDPE nanocomposites with the filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were characterized by the pulsed electro-acoustic (PEA) test at 40, 60 and 80 °C, and the charge mobility was evaluated by its depolarization processes. The experimental results show that for the undoped LDPE film, large amounts of space charges were injected from the electrodes into samples, especially at 60 and 80 °C. The graphene/LDPE nanocomposites with a filler content of 0.005 wt % could markedly suppress the space charge injection and accumulation even at 80 °C, which is attributed to the large quantities of graphene-polymer in interface regions. These interface regions introduced numbers of deep trap sites within the forbidden band of nanocomposites, which can reduce the de-trapping rate of charges and suppress the space charge accumulation in the polymer bulks. The graphene/LDPE nanocomposites are suggested for dielectric applications, intending the inhibition of space charge injection and accumulation. Polyethylene-based insulating materials, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), cross-linked polyethylene (XLPE) and so on, are widely used for electrical insulation, due to their excellent electrical and mechanical properties ,2,3. Amo2), zinc oxide (ZnO) etc., are considered to be optimal additives for HVDC cable insulation [Nanodielectric insulation has been one of the research hotspots to develop the advanced polymeric insulation, especially for the PE-based insulation of high-voltage direct-current (HVDC) extruded cable ,10,11. Asulation ,14,15,16sulation . Howeversulation . The relGraphene, with a unique two-dimensional structure and a giant specific surface area, allows for theoretically higher interactions with a polymer matrix than the traditional nanofillers ,19,20. IThis paper proposes the inhibition effect of graphene for the injection and accumulation of space charge in LDPE. The space charge behaviors of graphene/LDPE nanocomposites with different filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were investigated by the pulsed electro-acoustic (PEA) method at 40, 60 and 80 °C. Additionally, the trap-controlled carrier mobility of LDPE nanocomposites was evaluated by the depolarization processes of space charge.3 were provided by Dow Chemical Company . The graphene synthesized by using a modified hummers approach were purchased from Tanfeng Graphene Technology Co., LTD. , of which the dimensions are 0.5–2 nm in thickness and 0.5–5 μm in diameter. The specific surface area of graphene is 1000~1217 m2/g.In this study, the LDPE powders with density of 0.92 g/cm12H25SO3Na) as a kind of anionic surfactant. The graphene was dissolved in ethanol by sonication for 30 min to disperse. And the SLS/ethanol mixture was slowly added into a graphene/ethanol mixture, which was put into a water bath in advance at about 75 °C, then magnetically stirred for 12 h and sonicated for 1 h. The mass ratio of the SLS to the graphene nanofillers is 1:100. The surface-modified graphene was dried in a vacuum oven at 80 °C for 12 h to remove solvent. Then the treated graphene was mixed with the LDPE powder with different nanofiller contents of 0.003, 0.005, 0.007 and 0.01 wt %. Then the melt blending was conducted in a twin-screw continuous mixer with a rotation speed of 40 rpm at 160 °C for 20 min. The mixed compounds were hot-pressed in a stainless-steel mold with a thickness of 250 μm at 160 °C under 15 MPa for 20 min. The cool down process was done with pressure for 1 h.The surface treatment of graphene was carried out using sodium lauryl-sulfonate . The freezing microtome section of nanocomposites is investigated by using a Transmission electron microscopy  to represent the arrangement of the graphene within the matrix.Thermal analysis of the films was performed with a Differential Scanning Calorimeter . Temperature ranged from 20 °C up to 200 °C and vice versa for cooling scans performed with a heating/cooling rate of 10 °C/min in a nitrogen atmosphere. A three minute-time with temperature remaining at 200 °C was applied to erase the history of the thermal behavior of the samples (7 mg) for evaluating changes during the cooling scans. Endotherms were represented with upward curves in the scans.The space charge characteristics of graphene/LDPE nanocomposites at 40, 60 and 80 °C were measured by the PEA method proposed by T. Takada . The expε is the permittivity of sample. q’(t) = q+(t) − q−(t), where q+(t) and q−(t) are the average charge densities of positive and negative charges. q(t) stands for the average charge density in the specimen at a depolarization time of t, which is calculated by:L is the thickness of samples, and the thermal expansion at experimental temperatures is neglected. q is the space charge density in the specimen where x stands for location and t stands for depolarization time.The carrier mobility of graphene/LDPE nanocomposites can be calculated according to the space charge dissipation process, approximately ,25. The (a)μ is considered as constant in space and varies only with time.The carrier mobility (b)ρ is much larger than that of free charges fρ.The volume density of trapped charges (c)T(t)J is equal to L·dq(t)/dt.The hole-electron recombination is ignored. Hence, the charge dissipation only comes from the bulk transport of space charges to the ground. The total current density The Equation (1) should be under the assumptions that :(a)The cq’(t) = q(t) [Furthermore, we made a simplification, i.e., ) = q(t) . This ask is the Boltzmann constant. T is the absolute temperature. ν is the escape frequency of trapped charges, which is equal to kT/h. h is the Planck constant. e is the electronic charge quantity. R is the average distance of localized states. Even though some of the above assumptions are very strong and do not reflect the real conditions in most cases, the Equations (3) and (4) still could be used to evaluate the trap-controlled carrier mobility in polymer approximately.Additionally, the trap level involving the depolarization process can be obtained by :(4)φ(t)=X) can be calculated by the formula as follows [H0 is the melting enthalpy of LDPE fully crystallized (100%) and generally ∆H0 = 293 J/g [mH is the melting enthalpy of LDPE nanocomposites investigated. The degree of crystallinity characterized by DSC tests was 36.5%, 37.0%, 37.2%, 41.2% and 42.5%, for 0 wt %, 0.003 wt %, 0.005 wt %, 0.007 wt % and 0.01 wt % for graphene/LDPE Nanocomposites, respectively. The incorporation of graphene increased the crystallinity of PE nanocomposites. It is indicated that the well-dispersed graphene fillers acted as the heterogeneous nucleating agents, thus accelerating the rate of crystallization and enhancing the crystallinity of LDPE composites. follows :(5)X=ΔHm 293 J/g . ∆Hm is The space charge dynamic behaviors of graphene/LDPE nanocomposites with different filler content at various temperatures are shown in It is obvious that both the ambient temperature and graphene addition had a marked effect on the injection and accumulation of space charge. For the 0, 0.003, 0.005 and 0.007 wt % samples at temperature of 40 °C shown in The space charge behaviors at 60 and 80 °C were prominently modified by the introduction of 0.003 and 0.005 wt % graphene, as shown in For the neat LDPE, few space charges were injected into the bulk at 40 °C, but an aggravated injection and accumulation of space charge occurs at 60 and 80 °C, as shown in For the neat LDPE at 60 °C shown in With the increase of temperature to 80 °C, the injection and transportation of electrons (including both injection and ionization) were further accelerated, thus leading to more severe space charge accumulation at the polarization time of 1 min. What is even more remarkable was that the large quantities of positive charges injected from the anode into samples, as shown in For the graphene/LDPE composites with different filler content at 40 °C, most homocharges were accumulated near the electrodes, and few space charges were injected into the bulks except for the 0.01 wt % graphene/LDPE nanocomposites shown in At temperature of 60 °C, negative charges became dominated due to the acceleration of ionization and electron injection. By comparing the space charge color images in The rising of temperature from 60 to 80 °C would further accelerate the injection and transportation of holes. It can be observed in As the filler content reached to 0.01 wt %, homocharge injection and transportation were significantly accelerated under the co-effect of electric field and high temperature, as shown in The results shown above indicate that the 0.005 wt % graphene/LDPE nanocomposites had the fewest amount of injected space charges and the weakest electric field distortion at any ambient temperature, due to the effect of the interaction zones between graphene and LDPE matrix. However, as the filler content reaches 0.01 wt %, it may lead to an acceleration of the homocharge injection and transportation, thus aggravating the space charge injection and accumulation in LDPE nanocomposites.The space charges dissipation process can provide an estimation of the apparent trap controlled mobility and trap level by using Equations (3) and (4). According to the assumptions explained in q(t)) in LDPE samples during the depolarization process of 15 min were calculated by Equation (2) and presented in 3 at 5 s, and decayed with time nonlinearly. The decay rate of charge density declined with time, due to the deeper traps involved in the depolarization process. It was also observed that the 0.003, 0.005 and 0.007 wt % graphene/LDPE nanocomposites all had much lower initial charge densities and slower charge decay rates than that of neat LDPE. As shown in The average charge densities  became more active than electron as the ambient temperature rises to 80 °C. It is due to the hole having a high injection barrier at polymer-semiconductive material interface and a lower transfer rate in LDPE bulks than the electrons at lower temperature. With the rise of ambient temperature, the de-trapping and transfer rate of holes (including both injection and ionization) were significantly enhanced, resulting in a significant injection and transportation of holes at 80 °C. With the hole injection from the electrode into samples, the hole-electron recombination occurred in the vicinity of the anode, thus leading to the replacement of heterocharges with homocharges in the nearby anode.deP) of charges from traps can be expressed as [TE is the energy level of traps, ATEν is the attempt-to escape frequency, which can be represented as [d is the number of defect movement directions. h is the Planck’s constant. ν is the vibration frequency around the defects at the orthogonal plane flaw of moving direction. The ATEν can be considered as a constant that is equal to 2.85 × 1013 s−1 at 60 °C (333.15 K) [deP) at 60 °C are presented in −3 to 8.4 × 10−5 s−1. The lower the de-trapping rate in dielectrics, the more difficult the charge injection and transport. With a further increase of graphene from 0.005 to 0.01 wt %, the local overlapping between the interface regions or even the agglomeration Pde=νented as :(7)νATE=33.15 K) . The trashown in  lead to 2, ZnO, the optimum content is in the range of 0.5~5 wt % for the modification of space charge behaviors. Owing to the advantage of two-dimensional structure and an enormous specific surface area shown in The experimental results and discussions both indicate that the surface-treated graphene with a content of 0.005 wt % could significantly inhibit space charge injection and accumulation in LDPE. As concluded in the references ,14,15,16Negative charge was always dominant in the samples under voltage applied at 40 and 60 °C, while the hole injection and transportation became more active than electron as the temperature rises to 80 °C, resulting in the replacement of heterocharges with homocharges in the vicinity of the anode.The graphene filling with a filler content of 0.005 wt % brought in a large quantity of filler-polymer interface regions containing deep trap sites, which could reduce the detrapping rate of charges and effectively inhibited the space charge injection and accumulation in the polymer.Large amounts of heterocharges were formed in 0.01 wt % graphene/LDPE nanocomposites under 30 kV/mm at 60 and 80 °C, and the trap-controlled carrier mobility became higher than the undoped sample.In this paper, graphene/LDPE nanocomposites were prepared. The space charge dynamic behaviors of graphene/LDPE nanocomposites at ambient temperature of 40, 60 and 80 °C were investigated. The effects of graphene content on the space charge characteristics of LDPE were analyzed, and an inhibition effect of graphene with a content of 0.005 wt % on the injection and accumulation of space charge in LDPE is proposed. The main results and conclusions can be summarized as follows:


Here we show a unique hybrid chemical doping method that results in high transmittance uniformity in a layered graphene-polymer nanocomposite with suppressed defect-induced carrier scattering. This layer-by-layer hybrid chemical doping results in low Rs (15 Ω/sq at >90% transmittance) and 3.6% transmittance uniformity (300–1000 nm) compared with graphene (17%), polymer (8%) and ITO (46%) films. The weak localization effect in our nanocomposite was reduced to 0.5%, compared with pristine (4.25%) and doped graphene films (1.2%). Furthermore, negligible Rs change (1.2 times compared to 12.6 × 103 times in ITO) and nearly unaltered transmittance spectra were observed up to 24 GPa of applied stress highlighting mechanical flexibility of the nanocomposite film.A traditional transparent conducting film (TCF) such as indium tin oxide (ITO) exhibits poor mechanical flexibility and inconsistent transmittance throughout the UV-VIS-NIR spectrum. Recent TCFs like graphene films exhibit high sheet resistance (R Numerous exotic behaviors such as the anomalous quantum Hall effect, the Klein paradox, coherent transport, extraordinarily high mobility, optical modulation, and persistent photoconductance are observed in graphene10. High quality, flexible transparent conducting films (FTCF) are among the crucial building blocks for optoelectronic technologies ranging from flexible touchscreens to rollable displays, flexible light-emitting devices, and flexible energy conversion applications. Traditional transparent conducting films (TCF) such as indium tin oxide (ITO) are not suitable for flexible electronics technology upgrades due to their poor mechanical flexibility13 and inconsistent transmittance near the UV-VIS-NIR region4. Several nanomaterials such as nanowires17, conducting polymers19, metal-polymer layered hybrids20, and carbon nanotubes21 have shown some potential to replace ITO. Nevertheless, there are numerous challenges in these materials, for example, CNTs and metallic nanowires suffer from long-term instability, uneven surface morphology, and high contact resistance. Conducting polymers and metal hybrids are inadequate due to their large sheet resistance (Rs).Monolayers of carbon atoms packed into a honeycomb lattice in two-dimensional (2D) space (graphene) demonstrate extraordinary electronic and optoelectronic properties22. Mechanically exfoliated suspended graphene flake exhibits remarkable mobility (2.3 × 105 cm2/V s)10. However carrier mobility plummets (2 × 103−2 × 104 cm2/Vs) significantly due to the substrate-induced scattering upon transferring graphene layers onto external substrates23. Carrier scattering can be reduced in graphene (mobility of 8 × 104 cm2/Vs) by transferring it on top of a 2D hexagonal boron nitride (h-BN) or epitaxial ferroelectric gate oxides materials (1.4 × 105 cm2/Vs) as demonstrated previously24. However, most of these results were obtained in nanometer scale devices at low temperatures. Unfortunately, large-scale graphene synthesized by different methods25 results in crystalline graphene domains separated by grain boundaries, carbon vacancies, hexagonal lattice defects, and a randomly distributed structural ripple over the surface. These defects, ripples, and grain boundaries, along with substrate induced interfacial trap charges, react as carrier scattering centers and drastically reduce carrier mobility. Numerous adaptations have been made to overcome these challenges for flexible transparent conducting films, such as the use of large area graphene synthesized by chemical vapor deposition (CVD)26, interconnected graphene networks27, reduced graphene oxide films29, graphene Langmuir–Blodgett hybrid films30 and graphene-polymer nanocomposites33. However, a comparable TCF performance to that of ITO (Rs 10 to 20 Ω/sq at >90% transmittance) has not been achieved to date due to intrinsic defects, ripples, and grain boundary effects in graphene-based nano-carbon materials.Graphene is ideally suited as a transparent conduction layer due to extraordinarily high carrier mobility in atomically thin 2D space, transmittance up to 97.6%, and exceptional mechanical flexiblity2 substrates exhibits sheet resistance in the order of few hundred ohms with very high transmittance (around 97%)26. Sheet resistance can be reduced to ~30 Ω/sq (at 90% transmittance) by using chemical doping methods34. However, this value is nearly double that of conventional ITO performance as described above. A novel, comprehensive approach is required that incorporates high quality defect-free large-area graphene, improved graphene stacking, more efficient chemical doping, and non-graphene materials integration to overcome the TCF performance bottleneck.CVD-grown single layer graphene transferred onto SiOs in graphene-polymer nanocomposite that exhibits superior flexibility and transmittance properties. A unique chemical doping method was employed to achieve resistance quenching in the graphene-polymer nanocomposite film while maintaining high optical transparency (15 Ω/sq Rs at >90% transmittance). Furthermore, nominal changes in the nanocomposite film transmittance and Rs (1.2 times compared to 12.6 × 103 times change in the ITO) were obtained under severe applied mechanical stress up to 24 GPa. These outcomes highlight the strong application potential of novel hybrid nanocomposite materials for highly conductive, transparent and flexible electronics technologies.In this investigation, we demonstrate ITO comparable Rs at >90% transmittance. A 200 nm thick ITO thin film typically shows a transmittance spectrum as demonstrated in Fig. s of graphene and PEDOT:PSS thin films (with different thicknesses) transferred on top of polyethylene terephthalate (PET) substrate were compared with ITO performance in Fig. s however, decreases with increasing thickness, from 353 Ω/sq to 172 Ω/sq respectively  of pristine graphene sulfonimide (TFSA) have been previously investigated for graphene films34. Here we have compared these doping methods for graphene-polymer nanocomposites and optimized an effective strategy to decrease film Rs while maintaining the 90% transmittance for practical applications. A 30 mM dopant concentration was sufficient to achieve Rs saturation in previous investigations38. Therefore, 30 mM dopant (AuCl3 and TFSA) concentrations in nitromethane solution were spin coated (4000 rpm for 2 min) on top of the film, followed by hot plate annealing at 80 °C for 10 minutes. Figure 3, AuCl3, and TFSA doped single layered graphene films show similar values near 550 nm  which could be due to the formation of a gold nanocluster from Au0 and Au3+ ions38. These nanoclusters significantly decreased transmittance in AuCl3 doped single layered graphene coated with 46 nm polymer film throughout UV-VIS-NIR region. Figure 34. Two and three layers of stacked graphene films resulted in a reduction in transmittance of around 94.8% and 92.4% respectively as expected. In comparison, 46 nm, 241 nm, and 1260 nm thick PEDOT:PSS films show transmittance in the range of 96.7%, 91.7%, and 81.3% respectively at 550 nm  both exhibit irregular transmittance spectra over the spectral window between 300 nm to 1000 nm see Fig. . Graphen3, AuCl3, and TFSA doping methods respectively. It should be noted that the single layered graphene doped by HNO3 results in marginally higher transmittance of 98.1% compared to pristine graphene; this could be due to the etching and defect generated by the strong HNO3 acid solution34. In comparison, AuCl3 doping does not increase defects in graphene however, resulted in aggregation of gold Au0 and Au3+ ions on the film surface38. These aggregated nanoparticles scatter with incident light and reduce film transmittance. Different polymer film thicknesses were used on top of the chemically doped graphene films to further decrease Rs. Different thicknesses of the graphene-polymer nanocomposite in the graphene/AuCl3/graphene/AuCl3/polymer structures . TFSA doped nanocomposite with 90.6% transmittance results in Rs around 69 Ω/sq. Rs can be further reduced up to 37 Ω/sq by increasing nanocomposite thickness; however, transmittance reduces to less than 90% (88%). It is evident from the Fig. s without compromising much of the optical transmittance in nanocomposite films compared to the AuCl3 doping method. Therefore, a novel hybrid chemical doping method was developed, incorporating TFSA doping  and AuCl3 doping  respectively. This unique doping strategy enabled us to achieve Rs around 15 Ω/sq with 90.7% transmittance in the graphene/TFSA/graphene/AuCl3/TFSA/polymer/TFSA nanocomposite structure (“mixed doping strategy” legend). Increasing the nanocomposite film thickness from this point could decrease Rs further  due to less nanocluster formation from Au0 and Au3+ ions, however Rs was not considerably lowered (35 Ω/sq). Moreover, the transmittance variation in this structure was obtained around 8.4%. TFSA doping was introduced between graphene layers while keeping other layers identical (in the graphene/TFSA/graphene/AuCl3/TFSA/polymer/TFSA nanocomposite structure) in order to decrease the sheet resistance further without compromising transmittance below 90% , high transmittance (>90%), low transmittance variations (<4%), and transmittance maximum/minimum in the visible region demonstrate the advantages of this nanocomposite structure. Two time use of AuCl3 doping in the graphene/AuCl3/graphene/AuCl3/TFSA/polymer/TFSA nanocomposite structure resulted in comparable Rs (17.8 Ω/sq) however, transmittance reduced below 90% (89.1%). Three-layered graphene in the nanocomposite (graphene/TFSA/graphene/AuCl3/TFSA/graphene/AuCl3/polymer/TFSA) resulted in significant reduction in film transmittance up to 86% and resulted in similar Rs (14 Ω/sq). An optical micrograph of the chemically doped graphene-polymer nanocomposite on PET substrate is shown in Fig. The transmittance spectra of hybrid doping methods are compared in Fig. see Fig. . EncouraITO Fig. . This reITO Fig. . Low Rs 3 doping as described earlier. TFSA dopant solution consists of fluorine, nitrogen, and sulfur atoms38, whereas gold ions were observed previously in AuCl3 dopants34. Therefore, F1s, N1s, C1s, S2p, and Au4f XPS spectra were compared from higher to lower binding energies respectively  peaks were observed in DGPN and DG samples as shown in Fig. 2) peaks verified TFSA doping in DGPN and DG samples both for N1s and C1s spectra near 399.4 eV and 285.3 eV respectively. Moreover, nitrogen related bonds such as N-O (402 eV), -NH- (400.8 eV), and C = NH+ (401.6 eV) were observed in the N1s deconvoluted spectrum and confirmed TFSA doping in DGPN & DG samples respectively ; S2P3/2 (163.8 eV) peaks form PEDOT; and S2P1/2 (168.6 eV), S2P3/2 (167.8 eV) peaks form PSS, similar to previous investigations40. Sulfur related peaks from TFSA doping were also found in the DG sample, as shown in row 2 of Fig. 1/2 at 164.9 eV, and S2P3/2 at 163.8 eV). All of this evidence suggests strong TFSA doping in DGPN and DG samples compared to pristine graphene, where no fluorine, nitrogen, and sulfur-related peaks were observed  and Au3+ (near 82.9 eV) related peaks in the Au 4f XPS spectrum, similar to the previous investigations34. Although AuCl3 doping was used in DGPN sample however, the doping layer was covered with two-fold TFSA dopant layers and the 57 nm thick polymer layer; this could be the reason for the absence of gold-related peaks in Au 4f XPS spectrum. It should be noted that all of the samples showed strong C-C peaks (near 284 eV) from graphene however, PG samples showed conventional Sp3 carbon (nearly 284.4 eV), C-O-C (285.6 eV), and C-O=C (288.6 eV) related peaks in pristine graphene similar to the previous investigations39  and optoelectronic nanocomposite properties as demonstrated in this study.Charge transfer during the chemical doping process can be monitored using X-ray photoelectron spectroscopy (XPS). Figure see Fig. . Furthersee Fig.  of used 2/Si substrate  in the temperature range from 300 K to 2 K in the absence of a magnetic field. At 300 K, pristine graphene (PG) devices showed Rxx close to 570 Ω, whereas Rxx reduced to 200 Ω in DG due to chemical doping. Further resistance quenching was observed (102 Ω) in nanocomposite (DGPN), similar to the observed Rs trends. At low temperature (2 K), the Rxx value increased rapidly in PG (from 570 Ω to 647 Ω) and increased exponentially in DGPN (from 102 Ω to 270 Ω). In contrast, the value of Rxx dropped in DG (from 200 Ω to 168 Ω). These low temperature rapid Rxx increases in DGPN and PG could be attributed to mesoscopic resistance fluctuation effects near the neutrality point in graphene41. Furthermore, the mesoscopic resistance fluctuation effects are related to the increasing phase coherence length known as the weak localization effect in graphene42. This weak localization effect can be further confirmed by the sharp Rxx increase near zero magnetic field (B = 0). Figure xx with an applied magnetic field in the DG sample in the temperature range from 2 K to 90 K. The weak localization peak observed in Rxx near B = 0 resulted from electronic coherent backscattering effects similar to previous reports42. All of the samples  show weak localization peaks in Rxx near B = 0 at 2 K temperature  was similar to the film resistance as discussed in Fig. xx was observed in PG (~637 Ω at B = 0), followed by DGPN (~402 Ω at B = 0), and DG (168 Ω at B = 0). One of the intriguing facts to be noted here is that the carrier coherent backscattering caused by the weak localization effect was significantly reduced in the doped graphene-polymer nanocomposite (DGPN) sample. This was manifested by the reduction of weak localization peak height (at B = 0) in DGPN: up to 0.5% compared to 4.25% in PG and 1.2% in DG samples. These results strongly suggest that the reduction in carrier scattering and consequent resistance quenching in DGPN could be due to the reduction of grain boundaries, carbon vacancies, lattice defects and structural ripple-related carrier scattering processes.It is evident from the above investigations that graphene-polymer layered nanocomposites exhibit improved optoelectronic properties compared to its close counterparts such as graphene, polymer, and ITO films for FTCF applications. In addition, low-temperature transport measurements were conducted by pattering DGPN, DG, and PG samples in Hall-bar geometry on SiOsee Fig.  however,−5 S . In comparison, the chemically doped graphene sample exhibits surface conductance one order of magnitude higher in the range of 1.79 × 10−4 S  under applied compressive stress up to 23 GPa in a 100 nm thick ITO film and DGPN on a flexible PET substrate. Initially, ITO and DGPN films demonstrated approximately 10 and 15 Ω/sq sheet resistances respectively. The change in ITO sheet resistance remained small (1.07 times) up to very low applied compressive stress (6 GPa) whereas it increased sharply up to 12.6 × 103 times at 23 GPa. In this stage the ITO film demonstrated a very high Rs value of 4.2 GΩ/sq, suggestive of significant damage to the film. Previous investigations observed similar resistance increments in ITO film under applied stress  while maintaining high optical transparency (>90% transmittance at 550 nm) in nanocomposite films (comparable to ITO and lowest so far among carbon-based FTCF). Moreover, the nanocomposite shows tremendous transmittance uniformity (3.6%) in the VIS-NIR range (300 nm to 1000 nm) compared to graphene (17% in three-layered graphene film), polymer (8% in 100 nm thick) and ITO (46% in 200 nm thick) films. Furthermore, the carrier coherent backscattering and consequent resistance quenching in the nanocomposite were significantly reduced : up to 0.5% compared to 4.25% in pristine graphene and 1.2% in doped graphene films. Moreover, the nanocomposite film shows a nearly identical transmittance spectrum and negligible resistance change (1.2 times) under 24 GPa applied stress compared to 12.6 × 103 dopant was dispersed in nitromethane (Sigma Aldrich) and the supernatant was used as a spin coating solution  to implement chemical doping. High conductive PEDOT:PSS polymer solution (HIL-1005 from Sigma Aldrich) was spin coated on top of the doped graphene layers for graphene-polymer nanocomposite synthesis. Spin coating speed (from 1000 rpm to 6000 rpm for 60 sec) was controlled to achieve desired PEDOT:PSS thickness (from 46 nm to 1260 nm thick films respectively). Each nanocomposite layer was annealed at 80 °C for 10 min under atmospheric conditions during the synthesis process. A 30 watt oxygen plasma was used for 20 min for Hall-bar device patterning of the nanocomposite layers. 5 nm Cr and 100 nm Au thin films were deposited using e-beam metal evaporation process for device contacts. The sheet resistance of the fabricated samples was measured by four probe Van-Der-Pauw technique using a semiconductor characterization system (Keithley 4200). Commercially available ITO coated glass was used for transmittance and sheet resistance comparisons. A 100 nm thin ITO film was deposited on PET substrate for compressive stress comparison using RF sputtering system. AFM measurements were conducted using an SPA 300 HV, Seiko Instrument Inc. system. Field emission scanning electron micrographs were obtained from a JEOL JSM-6700F FE-SEM system. Transmittance spectra were obtained by using a UV–Vis spectroscopy system (Ocean Optics).Single layered graphene was synthesized using a low-pressure chemical vapor deposition (LP-CVD) system on 100 µm thick Cu foil. First, Cu foil was annealed for 5 hrs at 1020 °C under a 145 sccm argon and 29 sccm hydrogen gas mixture followed by chemical polishing using Cu etchant solution . Graphene growth was conducted at 1000 °C for 30 min under 500 mTorr with a 113 sccm methane and 12 sccm hydrogen gas mixture. The graphene layer was transferred onto the target substrate using the polymethyl methacrylate (PMMA) thin film and deionized water method. Commercially available PMMA (Sigma Aldrich) solution was spin coated on top of the graphene/copper foil with 700 rpm for 7 seconds followed by 1500 rpm for 60 seconds. This was floated on top of the commercially available Cu etchant solution (CE100) for 30 min and deionized water was used to wash etchant residues. Subsequently, the Gr/PMMA films were transferred to the target substrates and acetone was used to remove PMMA layers. 30 mM TFSA and AuClSupplementary Information