Sucha controlled hydrogenation of high-quality and high-specific-areasamples converts the original conductive graphene into a wide gapsemiconductor, with the valence band maximum (VBM) ∼ 3.5 eVbelow the Fermi level, as monitored by photoemission spectromicroscopyand confirmed by theoretical predictions. In fact, the calculatedband structure unequivocally identifies the achievement of a stable,double-sided fully hydrogenated configuration, with gap opening andno trace of π states, in excellent agreement with the experimentalresults.Conversion of free-standinggraphene into pure graphane—whereeach C atom is sp In graphane, the conjugationof graphene π electrons is thus disrupted, leading to an insulatingbehavior with band gap predicted to depend on the H chemisorptionconfiguration.2Maximum storage ofhydrogen in carbon-based materials is ideallyachieved in graphene by forming the so-called graphane, where eachcarbon atom in the honeycomb lattice is bound to hydrogen with alternatelyup and down sp14 with non-negligible contamination and defects. The maximum H uptakedepends on both the morphology of graphene specimens  and the hydrogenation methods. Several attemptsto incorporate a high percentage of hydrogen have been carried outin the last decades, exploiting a variety of strategies on differentsamples. Hot10 andcold14 plasma deposition and molecular H2 high-temperature cracking9 were applied to exfoliatedgraphene layers,10 to chemical-vapor-deposition(CVD) grown flakes,16 or even to metal–supported samples,17 reaching at most a partial hydrogenation of monolayergraphene, with an upper limit of H uptake Θ ∼ 36 at.%,14 while an almost stoichiometric bulkgraphane has been obtained from halogenated reduced wrinkled and layeredgraphenes.18 The limit of hydrogenationin single-layer graphene can be due to several concurrent drawbacks,such as oxygen contamination, the influence of the substrate, andthe presence of defects/edges in graphene flakes (either pre-existingor induced by the hydrogenation itself).Experimentally, however,only a low H storage capacity has beenreached so far (∼36 at. %) on single-layer graphene20—can present great advantages to achieve a high uptake ofhydrogen in graphene. The free-standing, curved structure at the submicrometerscale, with intrinsically smooth rippling, can foster hydrogen chemisorption,favored by the increased electron affinity of hydrogen and the energybarrier decrease in the convex regions21 induced by the pull out of the C atom toward the H proton.23A crucial challengeto fully exploit graphene for hydrogen storageis to employ defect-free graphene specimens with very high specificsurface area, where hydrogen can adsorb strongly enough on the surfaceas to form a thermodynamically stable arrangement, achieving an idealgraphane pattern. Nanoporous graphene (NPG)—constituted bya compact, bicontinuous interconnected 3D arrangement of high-qualitygraphene veils, composed of one to a few weakly interacting layers2/g)26 and very low density of defects, together with insitu, highly controlled hydrogenation by H2 cracking inthe ultrahigh vacuum (UHV) condition. In this way, we can controlthe absence of contamination of the sample during the H exposure andrealize a thermodynamically stable prototype of semiconducting graphane.A spectromicroscopy photoemission study, combined with state-of-the-arttheoretical predictions, demonstrates an unprecedentedly high H uptakein NPG, accompanied by a spectral electronic density of states aspredicted for ideal graphane, achieving for the first time an almostcomplete saturation in fully free-standing graphene of the availableC sites with hydrogen.We here exploit high-quality NPG samples, with high specificarea(1000 m2/g)26 arranged in a compact 3D structure; see 2) unveils the porous structure (pore size inthe submicrometer to few micrometer range) constituted by a foldedtubular graphene sheet with continuous almost flat areas and interconnectedchannels, with some wrinkles and without frayed edges.26 A detailed analysis of the NPG microscopic structure at the atomicscale, reported elsewhere,19 revealed moirésuperstructures due to suspended graphene layers with misoriented(turbostratic) stacking in some regions. Within this macroscopic 3Dgraphene architecture, the microscopic structure preserves all the2D graphene hallmarks.192), analogous to those employed for other suspended 2D systemssuch as hexagonal boron nitride bubbles,27 and after verifying that no detrimental effects were induced bythe laser beam on the NPG sample. The Raman spectrum presents a lowintensity of the defect-activated “D” Raman peak ifcompared to the “G” peak, associatedwith the doubly degenerate (iTO and LO) phonon modes at the Brillouinzone center. More importantly, the Raman spectrum shows a high intensityof the “2D” peak, a double-resonant second order modeactivated by in plane breathing of the hexagonal rings.28 The 2D/G Raman band intensity ratio was mappedover a mesoscopic area /[I(sp2) + I(sp3)].Hydrogen uptake can beidentified by the distortion of the pristineC–C sp3 being bound, has never been achieved experimentallybefore in fully free-standing low-defect graphene. In fact, only partiallyhydrogenated graphene was observed until now—either on transferredmonolayer flakes37 or on substrate-supported graphene8—with maximum uptake Θ ∼ 36%14 and with a high level of contamination and defects. Thepresent successful procedure can be ascribed both to the morphologyof the self-suspended, free-standing and bicontinuous NPG host andto the ultraclean and highly controlled, fully-UHV hydrogenation procedure.This extraordinary and unprecedented hydrogen uptake,which isin line with a chemisorption model for graphane with almost each Csp3 hybridization, due to the C–H bonding, to theopening of a semiconducting gap in graphane. Photoemission spectromicroscopyof both core levels and the valence band can combine local informationon the hybridization state (core levels), with the evolution of thespectral density close to the Fermi level  at the samespatial scale. We measured a spatially resolved photoemission mappingof a partially hydrogenated NPG sample (Θ ≈ 50%), asto be able to identify regions with different degrees of hydrogenation,correlating valence band with core level spectral shapes. 2 core-level component normalizedto the whole sp2 + sp3 signal, as deduced bythe fitting analysis (see Supporting Information) over the whole hydrogenated NPG specimen. This intensity variesin the map depending on the local hydrogenation state, as shown inthe exemplifying spectra of 2 hybridization isstill dominant [cross in panel (a)] correspond to the C 1s spectrumdisplayed in panel (b), while zones with higher values of sp3 component [star in panel (a)] correspond to the C 1s spectrum inpanel (c). The 10 × 10 μm2 blow up in 2 bond dominates, the spectraldensity of states presents a definite 2p-π peak at a bindingenergy of about 3 eV [see shaded area in panel (e)], which is thesignature of the graphene band structure, while in the regions wherethe sp3 component emerges, the spectral density drasticallychanges and the 2p-π peak is almost quenched. It is worth notingthat the density of states close to the Fermi level EF is strongly reduced for all the pixels where the sp3 component dominates.A crucial point is to correlate the appearance of the distortedsp%) the quenching of the density of states below EF suggests a definite transition to a semiconductingstate,as clearly observed in EF. Theascertainment of a definite correlation between the emergence of C–Hsp3 bonding and the position of the VBM unambiguously ascribesthe gap opening to the distortion of the bond to sp3, althoughthe assignment of the hydrogen adsorption sites cannot be unambiguouslyidentified from the photoemission experiment.At H saturation coverage (Θ ∼ 90Supporting Information). We hereafter report the results for three representative(the most stable ones) structures, that is (38); 2-side H-Gr, i.e.,graphane;2 and 2-side hydrogenated bilayer graphene(H-bGr). Quasi-particle corrections within the G0W0 approximation39 are included to overcome the DFT limitation in the descriptionof the electronic properties and ease the comparison with experiments(see Table S1 in Supporting Information). The single-sided hydrogenationleads to the appearance of an indirect gap of 5.6 eV. For the double-sidedhydrogenation, we predict a direct gap of 4.7 eV for the H-bGr and6.1 eV for H-Gr, the largest of the series, in line with previouscalculations.2 For a more direct comparisonwith experiments, in 40 Irrespective of the exact position of the VBMonset, the single-sided H-Gr system noticeably presents a structuredDoS at the VBM, originating from the 2p-π orbitals of the unsaturatedside, that is totally absent in the experimentally achieved saturatedphase of 41 without any 2p-π contribution, in excellent agreement withthe experimental data. Most of the spectral weight is indeed arisingfrom the sp3 hybrid orbitals, lying in the energy regionbelow −6 eV. This compares well in terms of energies and overallshape with the experimental spectrum . The experimental curve is, however, mostly featureless, probablydue to the specific spectral amplitudes in this energy range,42 not accounted for in our calculations. Overall,we can conclude that the calculated band structure and quasi-particleDoS unequivocally allow us to establish the achievement of double-sidedhydrogenated single- and bilayer graphene configurations.To corroborate and better understand the correlation between degreeof H chemisorption and emergence of a wide-gap semiconducting phase,we simulated by means of density functional theory (DFT) calculationsthe spectral density for different hydrogenated graphene phases, includingsingle-sided and double-sided hydrogenated single- and bilayer graphene,with different registry and hydrogenation configurations .Ni–10 mbar), and prior to the acquisitionthe NPG samples were degassed at 600°C for several hours to removecontaminants from air exposure. The sample was kept cooled at theliquid nitrogen temperature to avoid radiation damage.19 Valence band data with 21.22 eV photon energyon the saturated H-NPG sample was taken at the Lotus laboratory, Rome,by using an analogous UHV setup.The spectromicroscopyphotoemission experiments were performed at the ANTARES beamline ofthe SOLEIL synchrotron radiation facility. The nano-X-ray photoelectronspectroscopy (XPS) microscope is equipped with two Fresnel zone platesfor beam focusing, whereas higher diffraction orders were eliminated,thanks to an order selection aperture. The sample was placed on aprecision positioning stage located at the common focus point of thehemispherical analyzer and the Fresnel zone plates. This setup wasused for the collection of both point-mode spectra and imaging-modespectra. In the imaging mode, the photoemitted electron intensityfrom the desired energy range is collected over the sample to forma 2D image resolved at the submicrometer range. Core-level and valenceband spectra were taken with 350 and 100 eV photon energy, respectively.The spatial resolution was in the submicrometer range (near 600–700nm). The analyzer pass energy was set to 100 eV (200 eV) for the spatiallyunresolved (resolved) mode. All measurements were made under ultrahighvacuum (104 lasers (DPSSseries by Lasos) emitting at 532 nm. The Raman signal was spectrallydispersed by a 750 mm focal length ACTON SP750 monochromator equippedwith a 300 groove/mm grating and detected by a back-illuminated N2-cooled Si CCD camera (model 100BRX by Princeton Instruments).The laser light was filtered out by a very sharp long-pass Razor edgefilter (Semrock). The micro-Raman (μ-Raman) spectral resolutionwas 2.4 cm–1. A long working distance 100×objective with NA = 0.75 was employed to excite and collect the light,in a backscattering configuration. The laser spot size determinedexperimentally is characterized by a Gaussian shape with σ =0.28 μm. Moderate laser powers  were employed, afterchecking that the spectrum was analogous to that acquired with muchlower power (a factor of ∼70).For Raman measurements, the excitationlaser was provided by single frequency Nd:YVO48 The Perdew–Burke–Ernzerhof (PBE) generalized gradientapproximation for the exchange-correlation functional was used,49 together with Optimized Norm-Conserving Vanderbilt(ONCV) pseudopotentials.50 The quasiparticleband structure for the DFT optimized geometries was computed withinthe GW approximation to the electron self-energy,as implemented in the yambo code.54 Calculations were performed by employing an automated yambo-AiiDAbased workflow.57The ground-state properties ofH-passivate graphene were investigated from first-principles by usinga plane-wave pseudopotential implementation of the density functionaltheory (DFT), as available in the Quantum ESPRESSO package.


Idiopathic pulmonary fibrosis (IPF) is a severe interstitial lung disease; although the recent introduction of two anti-fibrosis drugs, pirfenidone and Nidanib, have resulted in a significant reduction in lung function decline, IPF is still not curable. Approximately 2-20% of patients with IPF have a family history of the disease, which is considered the strongest risk factor for idiopathic interstitial pneumonia. However, the genetic predispositions of familial IPF (f-IPF), a particular type of IPF, remain largely unknown. Genetics affect the susceptibility and progression of f-IPF. Genomic markers are increasingly being recognized for their contribution to disease prognosis and drug therapy outcomes. Existing data suggest that genomics may help identify individuals at risk for f-IPF, accurately classify patients, elucidate key pathways involved in disease pathogenesis, and ultimately develop more effective targeted therapies. Since several genetic variants associated with the disease have been found in f-IPF, this review systematically summarizes the latest progress in the gene spectrum of the f-IPF population and the underlying mechanisms of f-IPF. The genetic susceptibility variation related to the disease phenotype is also illustrated. This review aims to improve the understanding of the IPF pathogenesis and facilitate his early detection. Idiopathic pulmonary fibrosis (IPF) is a form of idiopathic interstitial pneumonia (IIP) characterized by progressive lung scarring, persistent decline in lung function, and poor prognosis IPF occurs in sporadic, familial, or syndromic forms -Pick disease Furthermore, IPF may occur in a familial setting, and patients with IPF show familial aggregation in different environments, suggesting a genetic cause Family cases of IPF were first described in 1907 by Sandoz However, it must first be speculated whether the sporadic and familial forms of IPF are indeed distinct manifestations of a single clinical entity, or whether they represent two distinct disease processes. Among relatives with f-IPF, the most common phenotype of interstitial lung disease (ILD) is usual interstitial pneumonia (UIP); however, in at least 50% of known familial cases, affected family members develop more than one ILD phenotype Genetic factors play an important role in both s-IPF and f-IPF TERT) TERC) DKC1) TINF2) RTEL1), zinc finger CCHC-type containing 8 (ZCCHC8), poly(A)-specific ribonuclease (PARN) SFTPC) SFTPA2) ABCA3) Susceptibility gene variation is informative for clarifying the pathogenesis of f-IPF and determining its key disease-causing targets. To date, there are no clinical guidelines on when and which gene tests should be performed in patients with IPF. Previous research has examined genetic associations, common single nucleotide polymorphisms (SNP) and rare gene mutations are associated with their development Telomeres are cap-like structures at the ends of chromosomes comprising multiple repeated 5ʹ-TTAGGG-3ʹ DNA sequences that protect chromosome integrity and stability during cell division Telomere shortening occurs gradually throughout the life cycle as cells undergo continuous mitosis, especially in individuals genetically susceptible to familial IPF who have significantly shorter telomeres than patients with sporadic IPF. The mutation of the telomerase complex accelerates telomere shortening. When telomere shortening reaches a critical value, DNA damage is activated, and mitochondria fail to divide, resulting in cell senescence, apoptosis, or cell division cycle termination.RTEL1, PARN, nuclear assembly factor 1 (NAF1), TINF2, ZCCHC8, and DKC1 and found that 18% of the patients had heterozygous TERT mutations, covering 18 mutation sites, and some patients may have several telomerase mutations TERT/TERC heterozygous mutations encoding RNA ligands of the telomerase complex in an autosomal dominant inheritance pattern TERT and TERC mutations have also been validated in another study in families with f-IPF Diaz de Leon et al. assessed 134 patients with f-IPF from 21 families with PF , which leads to the release of telomeric repeats (T-circles). These successive DNA cycle mutations gradually generate shortened telomeres RTEL1 mutants have very short telomeres, whose length is similar to those of peripheral blood mononuclear cells (PBMCs) in individuals with TERT, TERC, and DKC1 mutations RTEL1 also leads to genomic instability and replication defects RTEL1 are associated with the development of familial ILD, especially in patients with short telomeres in PBMCs RTEL1 is a DNA helicase that unlocks the T-ring structure of telomeres at the end of chromosomes PARN is a widely expressed enzyme that removes poly(A) tails by cap-dependent deadenylation of mRNAs and, in doing so, typically plays a role in regulating global mRNA levels during development PARN haploinsufficiency may lead to telomere shortening through a decrease in small nucleolar RNAs of the H/ACA box or TERC RNA composition. PARN mutations cause diseases that have been related to telomere length, including f-IPF PARN and RTEL1 mutations have shortened leukocyte telomere lengths, and family members who did not inherit PARN or RTEL1 mutations have shorter mean telomere lengths than unrelated individuals  but longer telomere lengths than carriers of PARN or RTEL1 mutations, with epigenetic inheritance of short telomeres observed in family members DKC1, is another component of the telomerase complex and is also important for its stability and maintenance DKC1; this domain would encode an amino acid substitution for Thr405Ala, a mutation that destabilizes TERC and impairs telomerase function DKC1 variant represents a telomere-associated gene for the genetic cause of f-IPF.The DC gene variant, X-linked gene TINF2 encodes a protein that is involved in telomere protection and maintenance TINF2, is a subunit of the shelterin complex. Mutations in TINF2 lead to telomere shortening and the impaired recruitment of tripeptidyl-peptidase 1 (TPP1)-dependent telomerase to telomeres TPP1-null mice increases telomere fusion and fragility. This confirms the role of TPP1 in telomere protection, which is required for TERT recruitment to telomeres and telomere elongation in vivoTINF2 mutations in a family with PF by exome sequencing. They confirmed that TINF2 mutations are a rare cause of f-IPF and explained the genetic risk in approximately 1% of the reported cases TINF2 mutations have also been reported in s-IPF ZCCHC8 loss leads to the accumulation of short-extended TERC forms while sacrificing mature TERC, possibly at an early stage, before PARN deadenylation ZCCHC8 mutations in an adult with IPF who exhibited typical features of short telomere syndrome and a family history consistent with autosomal dominant pulmonary fibrosis; 13 affected family members were deceased.ZCCHC8 is a component of the nuclear exosome targeting complex in mammalian cells ZCCHC8 variants or other short telomere syndrome phenotypes were found in 42 genetically-unidentified families that had also been screened for PF. This suggests that these mutations are rare (1 out of 43.2%). Furthermore, this result is consistent with a loci heterogeneity found in short telomere syndrome ZCCHC8 is essential for TERC 3ʹ-terminal maturation and telomerase function, and a loss in heterozygosity causes f-IPF Their TERC levels could not be measured to determine preclinical status; however, the proband's two children, who had abnormally short telomeres (shorter than those of the proband), had 50% lower TERC levels than healthy controls, and the remaining relatives had similar TERC levels to healthy controls. No NAF1 is a non-coding RNA that encodes an essential protein for the biogenesis of H/ACA box small nucleolus RNA. NAF1 affects telomere activity by combining with other proteins (such as TERT) to form telomerase, which plays an important role in telomeric DNA synthesis NAF1 function leads to short telomere syndrome, manifested as PF emphysema and telomere-mediated extrapulmonary disease, which is common in patients with s-IPF and f-IPF The association between telomere abnormality and PF is not fully understood In the absence of telomerase mutations, s-IPF is often associated with telomere shortening; 5.71-68.2% of s-IPF patients present shorter blood leukocyte telomeres than age-matched controls, most of whom had no identifiable telomerase gene mutation, suggesting that the pathways involved in familial disease contribute to sporadic disease Telomere length in peripheral blood is considered to be a marker of biological age Like IPF, emphysema is associated with cumulative DNA damage in alveolar epithelial cells, with age and smoking as major risk factors TRG) gene , suggesting that telomere dysfunction is associated with adverse outcomes after transplantation. Despite that, the 1-year survival rate after transplantation was above 80%, and the procedure was beneficial to the survival of patients with fibrotic ILD, regardless of telomere dysfunction TERT, RTEL1, or PARN variants Regarding lung transplantations, lung epithelial cell renewal rates are high. This leads to accelerated telomere wear, senescent reprogramming of airway progenitor cells, and ultimately, airway remodeling, and fibrosis Telomere length can be inherited independently of rare genetic variants, and inheriting short telomeres (and disease risk) without inheriting the mutation is possible; this is called “occult hereditary disease” TERT, TERC, DKC1, or other genes known to induce DC were detected A family history of short telomeres may be associated with neonatal respiratory distress, childhood ILD, aplastic anemia, and cryptogenic cirrhosis MUC5B) encodes major gel-forming mucin, which is mainly secreted by the proximal submucosal gland and distal airway, and plays a key role in mucociliary clearance In normal lungs, the airway secretion of mucus is a defense mechanism that traps pathogens, particles, and toxic chemicals floating in the air. The mucus also assists in the removal of endogenous debris, including dying epithelial cells and leukocytes, which are expelled from the airways by cilia and cough IPF has long been thought to involve mainly the alveolar region MUC5B is co-expressed in respiratory bronchiolar airway epithelia MUC5B expression was increased in tissue sections of distal airways from subjects with PF MUC5B transcriptional start site and is the strongest risk factor for the development of f-IPF MUC5BFOXA2) binding motif, which is differentially methylated in IPF MUC5B expression and rs35705950 being considered a risk allele. This hypermethylation may lead to increased occupancy of FOXA2 in the binding motif, resulting in increased expression of MUC5BMUC5B transcription. The resulting post-transcriptional processing can produce a pro-fibrotic response, induce endoplasmic reticulum (ER) stress, and activate the unfolded protein response (UPR) The gain-of-function promoter variant, rs35705950, is 3 kb upstream of the MUC5B gene, i.e., the rs35705950 variant. It poses a major risk factor for developing IPF, accounting for 30-35% of the risk When protein homeostasis is abnormal, UP accumulates in the ER, leading to increased ER pressure, which results in apoptosis. ER stress has been observed in patients with IPF MUC5B is involved in PF formation MUC5B rs35705950 variant significantly increase the risk of developing f-IPF and s-IPF. By scanning the entire gene sequence of the chromosome 11 p-terminal, 19 SNPs were found to be associated with f-IPF. Finally, rs35705950 located in the promoter region of MUC5B was confirmed to be the most strongly associated with familial lung stromal disease and IPF, present in 34% of familial lung stromal disease, 38% of IPF, and only 9% of normal controls, and was considered a risk allele for both diseases MUC5B has three CpG islands and other regulatory sites, suggesting that the expression of MUC5B is affected by both genetic and non-genetic factors.Plantier et al. studied the correlation between morphology and transcription factors in the signal transduction system in IPF and found that the uncontrolled expression of MUC5B promoter variant rs35705950 is the strongest risk factor for the development of f-IPF and s-IPF In 2011, two laboratories simultaneously reported that the MUC5B expression , resulting in a fibroblast-like phenotype in alveolar epithelial cells, as demonstrated in mouse (MLE-12) and rat (RLE-6TN) epithelial cells Krt5+), ablates the intrabronchial region, and assemble into alveolar structures First, excessive expression of MUC5B overexpression interferes with the interaction between AT2 cells and the underlying matrix, inhibiting alveolar basement membrane re-epithelization. This may exacerbate the ongoing alveolar collapse and fibrosis of adjacent bronchoalveolar units, resulting in chronic fiber proliferation and regeneration process disorders and cellular cyst formation Alveolar stem cells are mainly derived from the distal airway epithelium Second, under normal conditions, mucociliary clearance depends on effective ciliary movement, adequate hydration of the fluid layer around the cilia, and complete cough MUC5B and cilium-associated genes MMP7) is a WNT/β-catenin target gene encoding for a metalloproteinase, which is overexpressed in IPF proliferative epithelial cells. Based on the discovery that MMP7-deficient mice are protected from bleomycin-induced PF, it is speculated that MMP7 plays a role in promoting fibrosis MMP7 concentration in IPF was correlated with two single nucleotide polymorphisms in gene promoter regions, suggesting a potential genetic basis for MMP7 upregulation.Third, IPF is characterized by the co-overexpression of MMP7 has been proposed as a univariate predictor of early interstitial lung disease in first-degree relatives of patients with familial interstitial pneumonia MUC5B gene expression is associated with MMP7 concentration and attenuation of ciliary cell differentiation in the airways MUC5B promoter mutations cause mucus accumulation in the distal region of the lung and impair mucociliary function. Abnormal repair processes after distal airway injury and failure of terminal airway regeneration are activated by cellular cysts.A known biomarker of IPF can indicate the presence, severity, and prognosis of the disease MUC5B promoter SNP  have been identified in affected children and adults combined SFTPA2), although present in less than 5% of s-IPF, and 150 mutations in ABCA3SFTPC, SFTPA, and ABCA3 mutations. In humans, they occur in lung and AT2 epithelial cells of patients with f-IPF and s-IPF alike The central role of AT2 cells in IPF is to generate pulmonary surfactant ABCA3, ATP-binding cassette class A3 lipid transporter; AEC, Alveolar epithelial cells; cCK18, cleaved cytokeratin 18; CCL-18, CC chemokine ligand-18; CXCL, chemokine ligand; ECM, extracellular matrix; EMT, epithelial-mesenchymal transition; ER, endoplasmic reticulum; MMP, Matrix metalloproteinase; KL-6, Krebs von den Lungen-6; LOXL2, Lysyl oxidase-like 2; MUC5B, mucin 5B; SNP Single Nucleotide Polymorphism; OPN, osteopontin; SPA, surfactant protein A; SPA2, surfactant protein A2; SPC, surfactant protein C; SPD, surfactant protein D; TERT telomere RNA component; TERC, telomere reverse transcriptase; TLR3, Toll-like receptor 3; TOLLIP, Toll-interacting protein; Treg, regulatory T cells; UPR, unfolded protein response.Pictured are the alveolar lumen (top), epithelial cell layer (tan), interstitial space (white), and capillaries . Damage to alveolar epithelial cells by multiple stimuli (blue boxes) leads to epithelial dysfunction, fibrosis/extracellular matrix (ECM) deposition, and immune dysregulation. Proposed molecular biomarkers for these processes include blood proteins, genomic markers, and blood cells (see light purple/light green boxes). SP-C, SP-A, and ABCA3) cause stress and activate the unfolded protein response, AT2 dysfunction, and apoptosis, thereby promoting epithelial-mesenchymal transformation and the development of PF. ER, endoplasmic reticulum; TERT, telomere reverse transcriptase; TERC, telomere RNA component; MUC5B, Mucin 5B; SNP, single nucleotide polymorphism; TOLLIP, toll-interacting protein.Rare mutations of surfactant system components  and five introns, which produce an mRNA that encodes a 21-kDa proprotein (pro-SP-C 21) at either 191 or 197 amino acids. The pro-SP-C 21 COOH terminal, known as the BRICHOS domain (residue 90-197), is the carboxy-terminal region of the pro-SP-C proprotein. Most SFTPC mutations are located in the intrapeptide disulfide bond within the pro-SP-C COOH terminal (BRICHOS) domain SFTPC BRICHOS mutants are retained by the ER, inhibit the proteasome, and activate the UPR SP-C is a highly hydrophobic protein present in lung surfactants and is produced by ER integration of membrane protein precursors in AT2. The gene encoding SFTPC mutations occur in less than 5% of patients with sporadic IPF, these rare mutants enhance our understanding of AT2 cell and AEC cavity biology in PF. Lawson et al. demonstrated evidence of UPR activation markers (including heavy-chain- binding protein (BiP), ER degradation enhancing α-mannosidase-like proteins (EDEM), and XBP1) in patients with f-IPF expressing the L188Q SFTPC mutation and samples from non-SFTPC f-IPF and s-IPF cases Although Chronic ER stress in the alveolar epithelium may represent a broad mechanism of ILD pathogenesis The missense substitution G.1286T>C, which replaces isoleucine at position 73 in the SP-C preprotein (pre-SP-C I73T) with threonine, is the most common SFTPC mutation associated with ILD Furthermore, the expression of mutant SFTPC alveolar epithelial cells of mice drives the outbreak of a spontaneous FP. This demonstrates that AT2 cells can promote the creation of characteristic endophenotypes of IPF/UIP, including abnormal tissue remodeling to collagen deposition, AT2 cell proliferation, α-smooth muscle actin-positive cells, and limiting lung physiology SFTPA, encoding one of the two isomers of surfactant proteins, are associated with the heritability of f-IPF  In vivo, the expression of disease-associated SFTPA1 mutations leads to AT2 UPR activation, necrotizing apoptosis, and IPF, which are associated with ER stress-induced c-Jun N-terminal kinase (JNK) signaling SP-A, the most abundant surfactant-associated protein, is an intra-luminal multifunctional sialic acid glycoprotein. It has a molecular mass of 28-36 kDa and contains a COOH-terminal C-type lectin motif, triple helix collagen domain, and carbohydrate recognition domain SFTPA1 locus in two Japanese patients with f-IPF RIPK3) and mixed lineage kinase-like (MLKL) was detected in AT2 of SFTPA1 homozygous knockout mice, but both RIPK3 and MLKL could significantly improve the progression of IPF, suggesting that the SFTPA1 homozygous mutant reduced SP-A production.Takezaki et al. detected a homozygous mutation of the SFTPA1 leads to ER stress, which results in the overexpression of inositol requiring enzyme 1α (IRE1α) and increases JNK phosphorylation, thereby upregulating RIPK3 expression. The inhibition of IRE1α and JNK significantly inhibited RIPK3 expression and prevented the progression of PF. In contrast, these processes can be reversed by RIPK3 overexpression; this finding supports the idea that family genetic history can increase the susceptibility of IPF to external stimuli, aggravate the damage caused by the fibrotic process of AT2, and mediate the aggravation of IPF. Thus, RIPK3 may be an important target to treat IPF.Furthermore, we found that the loss of ABCA3, encoding for an ATP-dependent transporter that converts phosphatidylcholine and cholesterol into lysosome-associated organelles and is critical for lamellar formation, link lamellar body dysfunction to fibrotic lung disease. Human ABCA3 has been mapped to chromosome 16p13.3 and encodes a protein of 1,704 amino acids ABCA3 mRNA has been detected in many tissues, its mRNA is highly expressed in AT2 cells ABCA3 mutations lead to lamellar body deletion and neonatal respiratory failure in both humans and mice ABCA3 mutations exist with partial loss of function owing to ER retention (type I), improper functioning of the lipid pump (type II), or both (type I/II compound heterozygotes). These mutants act as genetic modifiers of pulmonary disease associated with SFTPC mutations in children Clinical mutations in SFTPC and D123N ABCA, increase disease penetrance, suggesting an interaction between these genotypes; however, the molecular mechanism between them remains unclear ABCA3 mutations are associated with PF, and cell phenotypes derived from ABCA3 mutations are found in isotypes, ER retention, and misallocation homotypes based on protein behavior ABCA3 mutants, changes in cell quality control, and fibrosis require further investigation.The heterozygous variants, I73T F-IPF is rarely identified in patients before disease progression, which limits our ability to study mechanisms. Identifying diagnostic and prognostic biomarkers and mechanisms helps to understand the pathogenesis of early f-IPF. Recent studies have increased the understanding of the underlying genetic susceptibility to PF and the pathogenesis of this disease. Genomic factors can also influence the development of f-IPF and the observed heterogeneity in pathogenicity. Genetically susceptible broncho-alveoli may sustain disproportionate damage at different time points owing to different environmental exposures and can eventually manifest as PF.A positive gene diagnosis may be significant for the early detection, prognosis, and risk assessment of close relatives, and genetic testing may be beneficial for patients with high FIP and positive gene probability The relationship between the mechanisms of rare and common genetic variations in FIP is not fully understood; they are thought to act synergistically to modulate disease-related phenotypes, such as telomere shortening. In addition, when considering lung transplantation, a positive genetic diagnosis in patients with f-IPF helps predict disease course and assess the risks. Further research should be aimed at revealing the underlying and pathogenic genetic factors and epigenetic changes in patients with f-IPF to improve the usefulness of precision therapies.


The photoelectrons were extracted through the graphene protection layer in a reflection mode, and we achieved QE of ~ 0.17% at ~ 3.4 eV, 1/e lifetime of 188 h with average current of 8.6 nA under continuous illumination, and no decrease of QE at the pressure of as high as ~ 1 × 10–3 Pa. In comparison, the QE decreased drastically at 10–6 Pa for bare, non-protected CsK2Sb photocathodes and their 1/e lifetime under continuous illumination was ~ 48 h. We attributed the improvements to the gas impermeability and photoelectron transparency of graphene.Protection of free-electron sources has been technically challenging due to lack of materials that transmit electrons while preventing corrosive gas molecules. Two-dimensional materials uniquely possess both of required properties. Here, we report three orders of magnitude increase in active pressure and factor of two enhancement in the lifetime of high quantum efficiency (QE) bialkali photocathodes (cesium potassium antimonide (CsK In recent years, however, there has been growing interest in their use as high-brightness photocathodes for advanced accelerators and electron microscopes. The next-generation accelerators require high-brightness electron bunches in short pulses that cannot be achieved with thermionic or field emission electron sources. Cesium potassium antimonide (CsK2Sb) is one of the best performing photocathodes available with a good balance between QE and the operation pressure15.The QE can exceed 10% at 532 nm and operation pressure is at 10–8 pascals (Pa). Metal photocathodes are the most robust type known, but the QE is generally in 10–3–10–4% with an exception of cleaned magnesium (Mg) that can reach as high as 0.3% at ~ 250 nm16 and cannot be driven by a high-power green laser. Cesiation of surfaces such as gallium arsenide (GaAs) and metals is an alternative, however, extreme ultrahigh vacuum of ~ 10–9 Pa is necessary to maintain the QE17. The promise of CsK2Sb as an electron source for accelerators is supported by the demonstration of record-high beam currents of 60 mA in a DC injector with 30 h 1/e lifetime5.Bialkali antimonides have been established as high quantum efficiency (QE) semiconductor photocathodes since their discovery in the 1950s. Historically, they have been widely utilized as photosensitive materials in radiation detectors and camera tube technologies–8 Pa and short operation lifetime. Increasing the operation pressure and extending the lifetime of bialkali antimonide photocathodes will reduce the number of replacements needed and the time lost for tedious photocathode replacement procedures (including a weeks-long baking of the system). Furthermore, the increased operation pressure will broaden the types of accelerators that bialkali antimonide photocathodes can operate in. There had been previous attempts to protect free-electron sources. Around year 2000, there were a collection of studies to coat bialkali photocathodes with 10–20 nm of more robust materials such as sodium iodide (NaI), cesium iodide (CsI) and cesium bromide (CsBr)21. While they succeeded in increasing the operation pressure, the thickness of the coating was similar to the thin photocathode thickness itself thus the concept was rather hetero-structuring than coating. With an advancement of two-dimensional (2D) material research over the past decade or so23, it is timely to apply the coating concept again with 2D materials. The 2D materials uniquely possess critical material properties for the purpose; namely, electron/photon transmissivity and gas impermeability. Graphene for example, transmits electrons due to its atomic thinness while being impermeable to gases due to its packed hexagonal atomic structure. Its optical transparency for monolayer is as high as 97.5% in a visible range24. The geometric pore size of graphene is 0.64 Å, which make it impermeable to even helium (He) atoms29. In addition, graphene is chemically inert and electrically/mechanically stable, which are all advantageous as a protection coating layer.The remaining technical challenges for implementing these photocathodes in accelerators are their low operation pressure of 102Sb photocathodes between graphene and a thin metal film to evaluate the feasibility of using graphene as a protective layer for bialkali antimonides. Specifically, we deposited photocathodes on a free-standing bilayer of graphene and sealed them with a 15–35 nm thick Ni films. Photoelectrons were then extracted through the graphene protection layer in a reflection mode, and the photocathode lifetime under continuous light irradiation was investigated at 10–8 Pa. Lifetime of photocathodes without protection was also measured to provide a comparison. We followed the lifetime measurements with active pressure measurements, which measured the QE as a function of pressure to gain insight into whether the graphene protection can increase the operation pressure of CsK2Sb photocathodes or not.In this study, we sandwiched CsK2Sb photocathodes to evaluate the feasibility of graphene protection layer in improving their active pressure and the lifetime. Our strategy to achieve this was to deposit thin metal films onto CsK2Sb photocathodes via thermal deposition from the opposite side of graphene protection layer. We had already established a protocol to fabricate CsK2Sb photocathodes on graphene protection layer34 thus the remaining task was to select an appropriate sealing metal for our purpose. It is well known that substrate material has severe effects on the QE of deposited ~ 20 nm think CsK2Sb photocathodes8, therefore it was crucial for us to identify a metal with minimal degradation. We tested copper (Cu), gold (Au) and Ni as metal substrates. Our QE testing method was to deposit CsK2Sb photocathodes onto commercially available metal foils rather than depositing thin metal films onto CsK2Sb photocathodes. We assumed that this testing method will provide us with necessary information regarding material compatibility between the metals of interest and CsK2Sb. The same CsK2Sb deposition conditions as that for graphene protection layer was used for consistency (see Method section for details). Cu was chosen for its high thermal conductivity, which could meet the needs to operate photocathodes in cryogenic temperatures such as that for cavity structures. Au was chosen for its chemical inertness, which could prevent photocathodes from interacting with corrosive gases such as oxygen and moisture. Ni was chosen for its potential material compatibility with CsK2Sb based on our prior studies34. We did not test molybdenum (Mo) despite its known material compatibility with CsK2Sb because of a concern on its high evaporation temperature. There is a report that the QE of CsK2Sb photocathodes start to degrade at temperatures higher than 60 oC11 thus we only tested metals with lower evaporation temperatures this time.Overall concept of this study was to create sealed CsK2Sb photocathode deposited on Cu, Au, Ni, and stainless steel (SUS) foil substrates at 10–8 Pa, where SUS was a reference. It was evident that QE was lower for every metal that we tested in comparison with SUS (12.8% at ~ 3 eV), however, Ni showed a minimal decrease compared to Cu and Au. Specifically, Ni showed the QE of ~ 12.5%  whereas the QE for Cu and Au substrates were as low as 6.5%  and 6.4% , respectively. Prior study of alkali photocathode deposition on Cu substrate reports alloying between Sb and Cu as a possible cause of the QE decrease. They performed in-situ synchrotron X-ray diffraction (XRD) and identified peaks associated with Sb-Cu alloy35. It is possible this is the cause of our observation on the QE decrease for Cu and Au substrates. The least decrease of QE observed for Ni substrate might indicate that the alloying between CsK2Sb is minimal among Cu, Au and Ni. This can be explained by electron affinity of Cu, Au and Ni, which Au has almost twice the value of Cu and the value for Ni is lowest among the three metals. Most direct technique to investigate the alloying between CsK2Sb and metal substrates of our interest is to perform XRD. However, this is not trivial as CsK2Sb quickly oxidizes upon its exposure to pressure above 10–6 Pa during the sample transfers. As an alternative, we coated monolayer graphene on Cu and Au substrates and deposited CsK2Sb on top of them to see if there is any improvement in the QE. We hypothesized that if we can reduce the QE decrease via graphene coating, then alloying is playing a role in the QE decrease as graphene is reported to perform well as a diffusion barrier for metals37. Figure –8 Pa. We observed a clear increase in the QE for CsK2Sb photocathodes deposited on graphene-coated Cu and Au substrates in contrast to non-coated counterparts in the dark environment . Moreover, graphene-coating prevented a QE decrease of CsK2Sb photocathodes even when the substrates were used multiple times. The QE decreased drastically when bare, non-coated Cu and Au substrates were used as substrates for multiple times after thermally cleaning off the photocathode films at 500–600 °C in vacuum for 1 h  and molybdenum (Mo) substrates31. In our previous study, synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) revealed that there was residual photocathode material on Si and Mo substrates even after the thermal cleaning, indicating that there was strong bonding/alloying between the photocathode and the substrates. In sharp contrast, we observed no residue after the cleaning for the graphene-coated substrates, which suggested that the strong bonding/alloying was no longer there. Therefore, the graphene-coating on Cu and Au is most likely acting as a diffusion barrier as expected. Our cross-section scanning electron microscopy (SEM) images on cesium antimonide (Cs3Sb) photocathodes deposited on graphene-coated and bare, non-coated Au substrates support the argument (taken after exposure to air). The Cs3Sb-Au boundary was sharp for a graphene-coated case  calculations also supported our hypothesis that graphene coating can prevent alloying between the photocathode elements and metal substrates. We calculated the binding energies between Cs, K and Sb atoms on Cu, graphene-coated Cu and graphene substrates as summarized in Table 2Sb photocathodes deposited on transmission electron microscopy (TEM)-grid-supported graphene. The QE was measured in a reflection mode from the CsK2Sb side, as illustrated by the inset, and measured at the pressure of 10–8 Pa. Successful CsK2Sb deposition on graphene is evident from a typical QE response that quickly increases around 2 eV and signature hump around ~ 2.5 eV. Moreover, the peak QE of ~ 13.6% at ~ 3.4 eV is consistent with our previous studies34.Figure 2Sb photocathodes through bilayer graphene protection layer prior to Ni seal was ~ 0.92% at ~ 3.4 eV, which is consistent with our recent study30. Our QE of CsK2Sb photocathodes through bilayer graphene protection layer takes TEM-grid transparency into account (see Method section for details). The QE dropped to ~ 0.17% at ~ 3.4 eV after Ni seal, most likely due to the chemisorption and the temperature increase during the Ni deposition . 15 nm thickness was selected based on the knowledge that metals need ~ 15 nm thickness to form uniform and continuous films, which is required for this study to exhibit sufficient seal. Metal films below 15 nm are reported to form islands unless unique treatments are performed on substrate surfaces to control the wettability of metals.The QE of CsK2Sb photocathodes. The first test was a lifetime under continuous illumination. The sealed photocathodes were irradiated continuously with a green laser (532 nm) and the QE was measured in a reflection mode through bilayer graphene protection layer under a pressure of 10–8 Pa. 1/e lifetime  of 188 h with average current of 8.6 nA was extracted from an exponential curve fitting  as the origin of degradation. Another known source of QE degradation is ion back bombardments40 although the effect may be much smaller compared to more susceptible surfaces such as that of cesiated GaAs. The collection voltage of 300 V can ionize H2 and H2 is known to permeate through graphene slightly more than other gases such as oxygen and moisture. Thus, it is possible that H2+ ion back bombardments are the source of QE decrease in our case. We plan to check this in a separate study by inducing controlled gases, including hydrogen, into the deposition chamber and monitoring the QE degradation.The origin of QE decay for bare, non-protected CsK30 and there is room for improvement toward the theoretical value of ~50% for monolayer. There are reports that have achieved up to ~ 60% electron transmission through monolayer graphene42, thus we plan to work on optimizing our material synthesis and device fabrication procedures to ensure the highest possible graphene quality in our next set of study. Ensuring the highest QE from CsK2Sb photocathodes is another factor that can be improved upon. The highest reported peak QE of CsK2Sb photocathodes can reach > 25% in contrast to the ~ 14% we observed in this study. Protected photocathodes with QE in the ~ 1% range and lifetime in the ~ 2-week range are expected after the above-mentioned issues of leakage, ion back bombardments, graphene material quality, and the QE of CsK2Sb photocathodes are solved.The challenge—aside from addressing the leakage/ion back bombardment issue—is to achieve high QE. We need the QE in the ~ 1% range for green to meet the demands for high-brightness advanced accelerators because of the commercially available laser power (~ 10 W). One way to address this challenge is to improve the quality of our graphene protection layer. The electron transmission efficiency through our current bilayer graphene is ~ 5%2Sb photocathodes can withstand their QE at average current of 2.4 nA. Similar to the lifetime under continuous illumination case, we irradiated the protected photocathodes with a green laser and measured the QE in a reflection mode through bilayer graphene protection layer. The pressure was gradually increased to atmospheric pressure by inducing air into the vacuum chamber. We observed no decrease of the QE up to ~ 1 × 10–3 Pa, which is three orders of magnitude increase in the active pressure of CsK2Sb photocathode . Furthermore, the active pressure of ~ 1 × 10–3 Pa for the graphene protected CsK2Sb photocathodes was one order of magnitude higher than that of Cu photocathode (~ 1 × 10–4 Pa)  Fig. b, a type2Sb, that can be excited by a green laser yet active in one order of magnitude higher pressure than metal photocathodes . Although the current level in this study is lower than those used in accelerator facility operations, the qualitative implication of our results on the future operation of photocathode components in accelerators can be large. Specifically, we may be able to reduce the replacement time of photocathodes from weeks to a few days. We may no longer need to remove all non-heatable parts for the baking to achieve ultrahigh vacuum pressures of 10–8 Pa. The increase of operation pressure will also broaden the types of accelerators bialkali antimonide photocathodes can operate in because of the reduced baking requirement.The significance of our achievement is that we succeeded in demonstration of a novel photocathode type using 2D material, graphene protected CsK2Sb with oxygen and moisture. We confirmed by SEM that TEM-grid-supported graphene substrates do not rupture upon their exposure to air when CsK2Sb was thermally removed at 500–600 °C prior to venting the deposition chamber  when exposed to air. This is most likely due to rapid chemical reactions/oxidation of CsK2Sb photocathodes and to improve their active pressure and lifetime under continuous illumination. We achieved an increase of three orders of magnitude in the active pressure and a factor of two enhancements in the lifetime of the protected photocathodes. Specifically, QE of ~ 0.17% at ~ 3.4 eV, 1/e lifetime of 188 h with average current of 8.6 nA under continuous illumination, and no decrease of QE at the pressure of as high as ~ 1 × 10–3 Pa were achieved. In comparison, the QE decreased drastically at 10–6 Pa for bare, non-protected CsK2Sb photocathodes and their 1/e lifetime under continuous illumination was ~ 48 h. Moreover, the active pressure of ~ 1 × 10–3 Pa achieved for our protected CsK2Sb photocathodes was one order magnitude higher than that of a bare, non-protected Cu photocathode, a type of photocathodes that is known to be the most robust. We attribute the active pressure and lifetime improvements to the gas impermeability and photoelectron transparency of graphene. Our results pave a pathway toward meeting the ~ 2-week turnaround time for feasible operation of accelerators using high-brightness bialkali photocathodes.To conclude, we investigated the efficacy of graphene-Ni thin film sandwich structure to seal CsK2Sb photocathode was then deposited onto the cleaned foil substrates. Briefly, the photocathodes were fabricated by sequential thermal evaporation of potassium (K), cesium (Cs), and antimonide (Sb) sources in a vacuum chamber with a base pressure of 1.0 × 10−8 Pa. Antimonide was deposited first for ~ 10 nm, followed by ~ 60 nm worth of potassium, and, finally, ~ 120 nm worth of cesium. The exact thicknesses of potassium and cesium were determined by the saturated QE values monitored during the growth using a 532 nm green laser. Detailed experimental setup for CsK2Sb photocathode deposition is described in Reference8. For cross-section SEM imaging, Cu and Au films with ~ 100 nm thickness was deposited onto Si single crystal substrate with 100 nm oxide layer via electron-gun (e-gun) evaporation.Commercially available Cu, Au, Ni and SUS foils were used as purchased (Alfa Aesar and Goodfellow). Those foil substrates were thermally cleaned in ultrahigh vacuum at 500–600 °C for an hour prior to the deposition. CsK43 on Cu substrates were purchased from Graphenea and transferred onto TEM mesh grids using an established polymer-supported method that involves distilled water exposure44. Bilayer graphene, instead of the monolayer, was used to minimize mechanical voids generated during the transfer process. Polymer support was removed using acetone. The graphene on TEM grids were thermally cleaned in ultrahigh vacuum at 500–600 °C for an hour to remove residue from polymer support during transfers. CsK2Sb photocathode was then deposited onto the graphene using the same condition as that for sealing metal selection. CsK2Sb photocathodes on TEM-grid-supported graphene were lastly sealed by 15–35 nm Ni thin films deposited via thermal evaporation. The deposition rate of Ni thin films was ~ 0.06 Å/s. The evaporation area of Ni thin film was 6 mm diameter circle thus large enough to cover the entire 3 mm diameter TEM-grid with CsK2Sb photocathode on graphene and seal it at the edge.Free-standing graphene was first prepared on commercially available TEM metal mesh grids with a 3 mm diameter. Graphene consisting of mainly monolayer regions with some multiple layer regions was synthesized via chemical vapor deposition (CVD)2, and the photocathodes were biased at −100 to −200 V to ensure the effective collection of photoelectrons. The laser power was adjusted to 0.6 mW, and the typical photo-current level was several µA for spectral response  and several nA for lifetime measurements. The QE spectral response for CsK2Sb photocathodes on TEM-grid-supported graphene was initially measured from the photocathode and the graphene sides separately. The QE from the graphene side was measured through bilayer graphene protection layer and it was measured before and after Ni thin film seal. In all QE that is measured from graphene side, the TEM-grid transparency of 40% is considered . The lifetimes of Ni sealed photocathodes were measured from the graphene side, under continuous illumination. A 532 nm green laser was used for all lifetime and operation pressure measurements. The lifetime measurements were performed at 10−8 Pa. The pressure was intentionally increased to atmospheric pressure by inducing air for the active pressure measurements.Reflection mode QE values were measured in vacuum using lasers in the visible wavelengths. The laser spot size was 0.5 mm45 as implemented in the Vienna ab initio Simulation Package (VASP)46. The generalized gradient approximation (GGA) of the Perdew–Burke–Ernzerhof (PBE)47 functional was used to represent the exchange–correlation interaction. The metal substrates were represented with slab models with a vacuum gap in the direction normal to the surface to eliminate the interactions between the replicas due to the periodic boundary conditions. The binding energies of adatoms are defined as Calculations were performed with the use of density functional theory (DFT) and the projector augmented-wave (PAW) method


Owing to the strong interface coupling, the graphene layer feels an effective confinement potential well imposed by two‐dimensional (2D) Mo2C crystal. Employing cross junction device geometry, a series of resonance‐like magnetoresistance peaks are observed at low temperatures. The temperature and gate voltage dependences of the observed resonance peaks give evidence for geometric resonance of electron cyclotron orbits with the formed potential well. Moreover, it is found that both the amplitude of resonance peaks and conductance fluctuation exhibit different temperature‐dependent behaviors below the superconducting transition temperature of 2D Mo2C, indicating the correlation of quantum fluctuations and superconductivity. This study offers a promising route toward integrating graphene with 2D superconducting materials, and establishes a new way to investigate the interplay of massless Dirac fermion and superconductivity based on graphene/2D superconductor vertical heterostructures.The realization of high‐quality heterostructures or hybrids of graphene and superconductor is crucial for exploring various novel quantum phenomena and devices engineering. Here, the electronic transport on directly grown high‐quality graphene/Mo 2C vertical heterostructures provide an ideal platform for exploring the interplay of massless Dirac fermion and superconductivity. This low‐temperature transport reveals the geometric resonance by the interaction of the carriers with the boundaries of the potential well formed at the graphene/Mo2C interface, and the potential well can be effectively modified through superconducting proximity effect in heterostructures.Directly grown graphene/Mo For these hybrid superconducting devices, a highly transparent superconductor‐graphene junction is critically important. Thus improving the quality of junction device and creating a clean and strong coupled interface is an essential part to investigate the fundamental quantum phenomena. Experimentally, previous studies on graphene/superconductor devices were usually prepared by the evaporation of superconducting materials over graphene. However, it is inevitable to create defects and contaminants at contact interface, and even it is difficult to induce superconductivity coupling with graphene by proximity effect. In addition, with the rise of van der Waals heterostructure, another technique of transferring and stacking 2D materials makes a compelling route to explore the proximity effect in hybrid graphene–superconductor devices. Whereas this transfer method depends on advanced techniques to produce sharp and clean interfaces, the devices also undergo weak interfacial interaction and interface contaminants leading to largely degrade device performance.In recent years, intense attention has been devoted to the study of graphene and other 2D crystals, which not only lead to the emergence of exotic electronic states, but also serve as atomically thin building blocks for the development of novel devices with new functionalities and promising applications.2, 3 By creating atomically thin graphene p‐n junction, various peculiar charge scattering characteristics for massless Dirac fermions, such as Klein tunnelling, Veselago lensing, and Berry phase switch, have been demonstrated experimentally. In previous experimental studies, different nanofabricated approaches are used for tackling the resonant scattering potential in graphene, such as etching antidots, substrate engineering, 1D electron guide, ballistic cavities, and depositing periodic gates. However, above nanopatterning procedures inevitably induce extra damage and reduce sample mobility by disorder. Additionally, due to the depletion at boundaries, a well‐defined scattering potential is hard to be realized resulting in a significant distortion of the electron cyclotron orbits. So far, these studies of transport in graphene subjected to scattering potentials have been limited to the nanofabrication techniques. The proximity effect induced scattering potential in superconductor/graphene heterostructure junction interface has not been explored.On the other hand, understanding the scattering processes in 2D materials and heterostructures is fundamentally and technologically important.14 By 2C, TaC, and WC. In α‐Mo2C crystals with excellent thermal and chemical stability, the 2D superconductivity has been demonstrated. For 2D heterostructures, we also have developed a two‐step CVD approach to fabricate high‐quality graphene/Mo2C vertical heterostructures with the double layers of Cu/Mo foils as growth substrates. Employing this approach, a high‐quality graphene/2D superconductor vertical heterostructure with uniform well‐aligned lattice orientation and strong interface coupling has been obtained. Compared with the van der Waals heterostructures by conventional transfer and stacking method, this directly grown 2D superconductor/graphene heterostructure has a clean and uniform interface, offering an interesting platform to explore the effect of interface scattering on the transport phenomena.Recently, we have developed a chemical vapor position (CVD) method to synthesize a series of high‐quality ultrathin transition metal carbides (TMCs) crystals, including Mo, and WC.27 In 2C vertical heterostructure devices. By fabricating graphene cross junction with heterostructure located in the central region, we are able to induce an electrostatic potential well to probe charger scattering in graphene. The magnetoresistance curves show a series of resonance‐like peaks at low fields. The temperature and gate voltage‐dependent magnetoresistance behavior are in quantitative agreement with geometric resonance scenario in which the cyclotron radius of incident electron is compatible with effective central scattering boundary. Moreover, the amplitude of magnetoresistance resonance peaks below the superconducting transition temperature Tc of Mo2C exhibit a different temperature dependence from the normal state, indicating that the presence of proximity‐induced superconducting gap can effectively modify the confinement strength of the potential well in heterostructure. Our results show that the vertical graphene/Mo2C heterostructure exhibit a clean and strong coupling interface for the study of the interplay between Dirac‐like quasiparticles and superconductivity.In this study, we investigate the low‐temperature transport properties of directly grown graphene/Mo22.12C heterostructure and device fabrication process is schematically depicted in Figure 2C vertical heterostructures has very high quality due to the unchanged reaction atmosphere and there is strongly coupled interface between graphene and 2D Mo2C crystal. Besides, the high crystalline quality of 2D Mo2C can be confirmed by HAADF‐STEM characterization; there is no visible defect or disorder in a large of ≈25 × 25 nm2 region  was performed to identify the sharp and uniform interface for our graphene/Mo2C heterostructures, as shown in Figure Ambient‐pressure CVD growth of graphene/Mo2C crystal as a scattering potential well on the charge transport properties of graphene, we fabricated a four‐terminal graphene cross junction with Mo2C in the central, as illustrated schematically in Figure 2C crystals. A typical measurement configuration for the cross junction device is manifested in Figure 2C/graphene devices by using conventional transfer method for comparison. The device fabrication process is schematically depicted in Figure In order to study the effect of Mo2.2Figure 2C with length scale of 1.8 μm is located in the center region of cross junction. The inset of Figure 2C crystal. Figure 2C heterostructure cross junction resistance as a function of backgate voltage obtained at zero magnetic field. The device exhibits p‐type transfer characteristics with the Dirac point located at around Vbg ≈5 V. The inset of Figure T = 1.9 K under high magnetic fields. The observation of quantum Hall plateaus also confirms that our direct growth method of graphene/Mo2C heterostructures have high quality. By applying the gate voltage, we can easily change the carrier density of graphene, which is an advantage for changing the Fermi wavelength of electron in graphene that can help to study the effects related to typical length scale of our device.R(B) of graphene/Mo2C heterostructure devices for various temperatures in the magnetic field range from ‐1 to 1 T. In order to characterize the transport through the pristine and heterostructured graphene in the cross‐junction region for comparison, we also fabricated a multi‐terminal Hall bar devices, as illustrated in the inset of Figure  By contrast, the heterostructure device in the presence of central Mo2C crystal displays a broad resistance bump structure, showing an increase of resistance below ±0.25 T. Another feature of the heterostructure device is the appearance of pronounced magnetoresistance oscillations at low fields. Figure T= 2 K, a series of resonance‐like magnetoresistance peaks can be clearly identified, superimposed on the magnetoresistance traces. These resistance peaks that appear at the specific magnetic fields are reproducible and stable, located symmetrically with respect to the zero field  and Mo2C (≈4.75 eV), charge transfer from graphene causes hole doping with the Fermi level displaced below the Dirac point, which is consistent with the observed p‐type transport characteristics. As a consequence, an electrostatic scattering potential well can be formed in the central heterostructure region. Similar potential barrier has been reported in other graphene heterostructures. The bottom panel of Figure  As a perpendicular magnetic field is applied, injected electrons move along the cyclotron orbits entering into the potential well imposed by the heterostructure, leading to additional charge carriers scattering at the boundaries. When the magnetic field is swept to meet resonance condition, the cyclotron orbits of electrons form a stable closed orbit which is confined within the potential well, giving rise to the magnetoresistance peak at certain magnetic fields. Similar commensurability magnetoresistance oscillations have been also observed in 2D electron gas subjected to a periodically modulated potential. According to the description of classical electron cyclotron motion radiuskF=2πns is Fermi wave vector, ℏ is Planck's constant, ns is the carrier density of the graphene. Thus, the resonance condition can be achieved by varying the magnetic field or carrier density.Considering graphene/Moachieved.31 Con2C heterostructure based junction devices, we carried out the gate voltage‐dependent magnetoresistance measurements. Figure Dirac ≈5 V). Thus, with increasing gate voltage in the hole side, the carrier density is tuned to decrease. When the gate voltage is increased approaching the Dirac point, it can be found that the resonance peaks gradually move to lower magnetic fields, as indicated by the dashed lines. Such evolution is expected from Equation (R(B) of stacked Mo2C/graphene devices using transfer method taken at different temperatures and gate voltages, respectively. In contrast to the magnetoresistance behavior of our grown directly Mo2C/graphene heterostructure devices, no resistance bump structure and oscillations were observed in stacked devices. The gate voltage evolution of magnetoresistance is also not regular. No noticeable feature of resonant scattering was observed. These comparative results further support that the presence of clean and strong coupling interface in our directly grown Mo2C/graphene heterostructures can effectively modify the potential well, being responsible for the observed geometric resonance.To further investigate geometric resonance in graphene/MoEquation  since th2.4n∝Vg. Therefore, we can quantitatively evaluate the B* by performing a square root dependence of the gate voltage. For clarity, the gate voltage at the Dirac point has been shifted to zero. Figure B* of order 3, 4, 6, 7 magnetoresistance resonance peak as a function of ΔVg1/2. The dashed lines show the results of linear fitting. It can be clearly seen that the values of B* scale with Vg1/2, which is consistent with the picture of geometric resonance in a hard‐wall potential well of 2D graphene/Mo2C heterostructure cross junction.We next carry a quantitative analysis of magnetoresistance resonance peaks. For monolayer graphene, the carrier density near the Dirac point is induced by gate voltage with linear dependence 2C is 1.8 µm and the area is close to 2.5 µm2, here approximately considered as an equilateral triangle model. For the third‐order resonant peak, the characteristic magnetic field B* is 0.11 T. According to the Equation 1/2/eBa, and kBTa(B) = ℏωckFa/4π2. The fitting results are shown as gray dashed lines in Figure Tc ≈ 4 K of 2D Mo2C, highlighted by the blue region in Figure Tc suggests a connection with superconductivity which is developed in Mo2C. For our graphene/Mo2C heterostructures, superconductivity would expect to be induced in graphene through strong couple interface. As a result, a proximity‐induced superconducting gap could be formed in the interface region, which has been identified in hybrid graphene‐superconductor structures by using scanning tunnelling microscopy. Comparing with the situation in the normal state, the presence of proximity superconductivity gap may modify the confinement strength of the potential well underneath the Mo2C in the junction region. Therefore, the different temperature dependence of the magnitude of resonance peaks provides the evidence for superconducting modification effect.Finally, we turn our attention to the effect of superconductivity on the magnetotransport properties of graphene/Mo. Figure 40 ∼ T−α with α ≈ 0.5, which is related to the dephasing mechanism of Coulomb interaction between charge carriers. As the temperature is further lowered, the growth of amplitude deviates from the ∼ T−0.5 dependence. The characteristic temperature (≈ 4–5 K) is comparable with the Tc value of Mo2C crystals, suggesting that the fluctuations are strongly influenced by the induced superconductivity in heterostructure. Previous experimental and theoretical studies in mesoscopic normal metal/superconductor systems have found that the proximity effect would modulate the conductance fluctuations, which have been attributed to the presence of the Andreev reflection at the interface. However, the magnitude of the fluctuations and its relation to superconductivity and mesoscopic structures remain a controversy. Our graphene/Mo2C heterostructure with clean and strong coupling interface may provide an ideal platform for studying the relationship between conductance fluctuations and proximity effect in graphene.We further take the analysis of overall conductance fluctuations averaged over magnetic fields, which can provide additional information on charge carrier scattering and dephasing mechanisms. In order to quantify the conductance fluctuations, we subtract the slowly varying background conductance. Figure 42 For32C vertical heterostructure. We observe a series of resonance‐like magnetoresistance peaks at low temperature. The evolution of the magnetotransport features with temperature and gate voltage can be explained in terms of geometric resonance by the interaction of the carriers with the boundaries of the potential well formed at the graphene/Mo2C interface. Further analysis of the amplitude of magnetoresistance resonance peaks and magnetoconductance fluctuations reveals the different temperature‐dependent behavior between the normal and superconducting state, indicating that the confinement strength of the potential well can be effectively modified through superconducting proximity effect in heterostructure. Our findings open the door to exploration of directly grown graphene/2D superconductor vertical heterostructures as the ideal platform for investigating the interplay of massless Dirac fermion and superconductivity.In conclusion, we have realized high‐quality hybrid graphene‐superconductor devices with clean and strong coupling interface based on directly grown graphene/2D superconducting Mo42C heterostructure followed these steps. A Cu foil was cut into pieces and placed on the top of Mo foil which had the same size of the Cu foil. Then, they were placed in a quartz tube as the growth substrate of graphene/Mo2C heterostructure. First, using methane  as the carbon precursor and under H2(200 sccm)/Ar(500 sccm) as the carrier gas, we set growth temperature of 1070 ° C in a horizontal tube furnace. After 30 min, the graphene has been formed. The Cu/Mo substrate was heated to 1090 ° C to grow 2D Mo2C. At the present temperature, Cu foil started to melt and covered the entire Mo substrate. The methane through graphene further reacted with Mo to form α‐Mo2C, which was underneath the graphene on the liquid Cu/Mo substrate. Finally, setting flow rate of methane made the samples cool down to room temperature.Ambient‐pressure CVD growth of graphene/Mo2C heterostructure on Cu/Mo substrate was confirmed by Raman spectroscopy with a 632.8 nm laser (Jobin Yvon LabRAM HR800). The cross‐sectional HRTEM image of graphene/Mo2C heterostructure was taken by TEM with a voltage of 300 kV (FEI Titan3 G2 60‐300), and cross‐sectional sample was processed by Focused Ion Beam with Ga source (Zeiss Orion NanoFab).Graphene/Mo2C heterostructures were transferred onto SiO2/Si substrates by means of conventional poly(methyl methacrylate)‐mediated method. After the transfer process, the graphene/Mo2C heterostructures crystals were selected and located by optical microscopy. Titanium/gold(5/90 nm) electrodes were patterned on each arm of the cross junction by means of standard electron beam lithography followed by electron beam evaporation of the metals. The electrical transport measurements were performed in a physical property measurement system (Quantum Design DynaCool) from room temperature to 1.8 K. Here, the standard four‐terminal resistance was measured using the low‐frequency lock‐in technique with an excitation current of 1–5 µA at a frequency of 17.77 Hz. The magnetic field was applied perpendicular to the plane of the sample.The graphene/Mod method.26 AftThe intensities of Raman data in Figure The authors declare no conflict of interest.Supporting InformationClick here for additional data file.


Objective: To investigate whether a higher number of transcranial direct current stimulation (tDCS) sessions results in a greater improvement in upper limb function in chronic post-stroke patients. Materials and methods: A randomized, sham-controlled, double-blind clinical trial was conducted in 57 chronic post-stroke patients (≥ 3 months after their injuries). The patients were allocated to receive sessions of tDCS combined with physiotherapy and divided into three groups . The Fugl-Meyer Assessment of Upper Extremity (FMA-UE) was used to assess the sensorimotor impairment of the patients’ upper limbs before (baseline) and after five and ten sessions. The percentage of patients who achieved a clinically significant improvement (> five points on the FMA-UE) was also analyzed. Results: The FMA-UE score increased after five and ten sessions in both the anodal and cathodal tDCS groups, respectively, compared to the baseline. However, in the sham group, the FMA-UE score increased only after ten sessions. When compared to the sham group, the mean difference from the baseline after five sessions was higher in the anodal tDCS group. The percentage of individuals who achieved greater clinical improvement was higher in the stimulation groups than in the sham group and after ten sessions when compared to five sessions. Conclusions: Our results suggest that five tDCS sessions are sufficient to augment the effect of standard physiotherapy on upper limb function recovery in chronic post-stroke patients, and ten sessions resulted in greater gains. Stroke is one of the leading causes of physical disability among adults worldwide , with apTranscranial direct current stimulation (tDCS) is a potential tool for increasing and accelerating cerebral cortex reorganization and facilitating motor learning by modulating cortical excitability . After aIncreasing evidence points to tDCS as an adjunctive treatment in post-stroke motor rehabilitation ,19. DespSeveral factors can influence the achievement of the best motor response with tDCS post-stroke, and questions still remain regarding the ideal dose of the number of sessions . Indeed,To the best of our knowledge, no randomized clinical trial has investigated whether higher doses of tDCS produce greater clinical improvement in upper limb motor function. The dose of a non-pharmaceutical intervention is unclear, and inconsistent terminology can incorporate multiple dose dimensions, such as frequency, intensity, duration, and intervention length . Here, tThis double-blind, randomized, sham-controlled clinical trial was performed between November 2017 and January 2019 at the Laboratory of Applied Neuroscience (LANA), Universidade Federal de Pernambuco, Brazil.www.clinicaltrials.gov (NCT03446378).All participants signed an informed consent form after being informed of the study objectives and procedures, which was performed in accordance with the Declaration of Helsinki. This study was approved by the local research ethics committee and was registered at Participants were recruited from a pre-existing list at the research laboratory via telephone. Patients of both sexes were included according to the following criteria: (i) diagnosis of hemorrhagic or ischemic stroke, confirmed by magnetic resonance imaging/computed tomography; (ii) ≥3 months after ictus; (iii) presence of sensorimotor sequelae in the upper limb; and (iv) age between 18 and 75 years. The exclusion criteria were as follows: (i) other neuromusculoskeletal injuries; (ii) cognitive deficits assessed by the Mini Mental State Examination (MMSE) ≤18 points ; (iii) cwww.randomization.com. This was stored on paper and kept in an opaque sealed envelope to keep the allocation confidential. Patients were randomized into three groups: (i) cathodal tDCS, (ii) anodal tDCS, and (iii) sham tDCS. The outcome evaluators were blinded to tDCS. A non-involved researcher was assigned to apply the tDCS. As such, this study was double-blinded.Randomization of patients who met the eligibility criteria was performed by an external researcher who was not part of any research process through the website Initially, patients were evaluated using the Fugl-Meyer Assessment of Upper Extremity (FMA-UE) at pretreatment (baseline) and after 5 and 10 sessions. The Global Perception of Change Scale was also applied after starting treatment of five and ten sessions. The intervention protocol consisted of ten sessions of tDCS combined with physiotherapy for two consecutive weeks (5 days a week) .During the tDCS intervention , two electrodes (5 × 7 cm) soaked in saline solution were applied to the scalp of the patients, applying a low-amplitude direct current (2 mA). The location of the primary motor cortex (M1) of the non-lesioned and lesioned hemispheres was based on the international 10/20 positioning system electroencephalogram. For the anodal tDCS group, the electrode was placed in the motor area ipsilateral to the lesioned hemisphere at points C3 or C4 (according to the 10/20 reference system), and the cathode was positioned over the contralateral supraorbital area. In the cathodal tDCS group, the cathode was positioned over the C3 or C4 motor area of the non-lesioned hemisphere, and the anode over the supraorbital area ipsilateral to the lesion. The sham tDCS group was subjected to the same procedure as the anodal tDCS group. The stimulation protocol lasted 20 min with a ramp up and down of 10 s, except for the sham tDCS group, which lasted 30 s to achieve a good level of blinding . After eAll patients, regardless of the stimulation group, underwent physiotherapy sessions. Each session consisted of kinesiotherapy for the rehabilitation of sensorimotor impairment of the upper limb, lasting 45 min. The kinesiotherapy protocol highlights 12 points following the neuroplasticity principles of Kleim and Jones . These tThe outcome of the present study was related to impairment of upper limb motor function through the Fugl-Meyer Assessment of Upper Extremity (FMA-UE). The FMA-UE includes the motor domain and coordination/velocity. There is a total of 33 items, each of which contains an ordinal scale of three levels: (0) cannot be performed, (1) partially performed, and (2) performed completely, with a total score from 0 (complete hemiplegia) to 66 points  for the upper limb ,43. The The normal distribution of data was analyzed using the Kolmogorov–Smirnov normality test. First, comparisons among the groups  at baseline were performed according to the demographic and clinical characteristics of the samples. The chi-square test was used for categorical variables, and the Kruskal–Wallis and one-way ANOVA tests were used for categorical variables.time (before and after 5 and 10 sessions) and among the factor groups . Mauchly’s sphericity test was used to evaluate the validity of the sphericity assumption, and when necessary, was corrected using the Greenhouse–Geisser test. The paired t-test was used to compare the baseline and post-intervention assessments (baseline to after five sessions and baseline to after 10 sessions) in each group.For the FMA-UE, repeated measurements for ANOVA 3 × 3 were calculated using the within-subject factor In addition, the number of patients who reached the minimal clinically important difference (mCID) of the FMA-UE was calculated at the end of 5 and 10 sessions. The assessment of patients’ mCID was considered as the minimum difference of five points obtained through FMA-UE for clinical improvement , which wp < 0.05).All statistical analyses were performed using the statistical software IBM SPSS , version 23.0, UFPE, Recife, Brazil for Windows, with a significance level of 95%  but not for groups  and interactions . Compared to the baseline, the FMA-UE score increased after five and ten sessions in the anodal and cathodal tDCS groups. However, in the sham group, the FMA-UE score increased after only ten sessions  between the anodal and sham groups after five sessions.p > 0,05; chi-square test). However, the percentage of people who achieved greatly improved and very much improved categorizations of FMA-UE was greater in the tDCS group than in the sham group after five and ten sessions  with ten sessions (the most common number of sessions among the studies) on upper limb function post-stroke recovery. Based on our findings, five tDCS sessions were sufficient to augment the effect size of physiotherapy on upper limb function recovery in chronic post-stroke patients. Previous research has demonstrated that both five and ten tDCS sessions can improve upper limb recovery.In our study, mCID was achieved in all groups after five and ten sessions, but for a greater number of participants in the stimulation groups  than in the sham group. These findings are consistent with a previous report that compared the mCID of three groups  combined with a physiotherapy technique after 12 sessions, at a frequency of three times a week . Taken tIt is important to mention that a meta-analysis  suggesteThe results of the present clinical trial showed that conventional therapy associated with anodal stimulation provided an improvement in upper limb function. These findings are in line with previous publications ,31,35, sAlthough there was homogeneity in the motor impairment level among our groups, a difference in patient stratification, regardless of the level of structural reserve, is likely to be the main limitation of our study. This could have influenced our result regarding the superiority of the anodal over the cathodal protocol. Nevertheless, in future studies, it may be interesting to compare the dose–response of both tDCS protocols in studies that choose stimulation protocols based on a neurophysiological evaluation of the level of the patient’s structural reserve. Another interesting direction for future work would be to compare the effect size of multiple tDCS sessions with clinical assessments in other domains of the International Classification of Functioning, Disability, and Health (ICF) , such asA further limitation of this study is that the sample size was not calculated; therefore, as this is related to the power analysis, the data should be interpreted with caution. Finally, a further limitation of the study is the lack of a cut-off for FMA in patients with different motor impairment levels.In summary, our preliminary evidence indicates that conventional therapy plus tDCS typically produces an earlier and greater effect than physical therapy alone, especially in anodal tDCS. Moreover, this clinical improvement is even faster and more effective with a minimum of five sessions, and as the number of sessions increases, clinical gains in upper limb function potentiate greatly.


The surface morphology, roughness, wettability, and degradation of coated and uncoated samples were analyzed by scanning electron microscopy, interferometry, and contact angle. The results showed that the specimens coated with NbGO (cp Ti-NbGO) showed the highest surface roughness (Ra = 0.64 μm) and were hydrophobic. The contact (θ) angle between water and the surface of uncoated specimens (cp Ti), coated with GO (cp Ti-GO), coated with a mixture with GO and Nb2O5) (cp Ti-NbGO), and coated with Nb2O5 were 50.74°, 44.35°, 55.86°, and 100.35°, respectively. The electrochemical corrosion tests showed that coating with graphene oxide increased the corrosion resistance and coating with Nb2O5 decreased the corrosion resistance. The negative effect of the effect of Nb2O5 coating in corrosion resistance compensated for the release of Nb2O5, which helps osseointegration, increasing cell viability, and proliferation of osteoblasts. The NbGO coating may be a good way to combine the bactericidal effect of graphene oxide with the osseointegration effect of Nb2O5.Graphene and niobium oxide are used in biomaterial coatings. In this work, commercially pure titanium (cp Ti) was coated with graphene oxide (GO), niobium pentoxide (Nb Titanium and its alloys are widely used as biomaterials. Its main feature is osseointegration since the titanium oxide film on the surface enhances the adhesion of proteins and bone cells. The wrought titanium 6-aluminum4-vanadium ELI alloy (Ti-6Al-4V ASTM F136), alpha plus beta titanium alloy forgings (ASTM F620), and wrought titanium 6-aluminum7-niobium alloy (ASTM F1295) have adequate mechanical properties for use as a biomaterial, but they release toxic ions (Al and V), decreasing its biological activity. Another problem observed is that among the different causes of failures of orthopedic prostheses and dental implants, the adhesion of biofilms and chronic inflammatory processes deserves to be highlighted. In the case of implants, biofilm adhesion can also facilitate peri-implantitis. Despite the various procedures adopted to minimize this problem, implant scraping and the use of antibiotics are the most efficient. Even so, the inflammatory process can be recurrent, leading to implant loss. For this reason, surface treatment and chemical modifications of titanium alloys for implant biomaterials application are important.Escherichia coli and Streptococcus iniae. In high concentrations, GO inhibits the action of Gram-negative bacteria [Graphene oxide (GO) has a bactericidal effect and does not inhibit cell growth. The antibacterial activity of GO is based on the production of hydroxyl radicals, which attack the cell membranes of bacteria, causing their death. During the process, reactive oxygen species are generated, which lead to oxidative stress, exceeding the antioxidant defense capacity of the bacteria and causing damage to their lipids, proteins, and DNA. The morphology of GO is formed by nanosheets with sharpened edges that break the bacterial membrane, causing the intracellular matrix to drain into the medium . GO inhibacteria .2O5) is the most stable thermodynamically [2O5 enhances cellular viability and proliferation after 21 days. The cells present good adhesion and are homogeneously distributed on the surface. Previous results showed that the lactate dehydrogenase activity was similar to the titanium surface with and without Nb2O5 coating, indicating a similar number of cells.Among niobium oxides, niobium pentoxide  were used in the present work. The material was supplied by Conexão Sistema e Prótese . The samples were acid-etched with a mixture of sulfuric acid, hydrochloric acid, and distilled water and washed in an ultrasonic bath with distilled water before all testing.2O5 and a mixture of GO and deposition and Nb2O5 followed similar routes. The deposition of graphene oxide was carried out by electrodeposition in an aqueous solution . The graThe surface morphology of three samples from each group was investigated by scanning electron microscopy  before and after coating.The sample wettability was measured by the contact angle method. Contact angle measurements were performed with deionized water, using the sessile drop technique. The equipment used was the FTA 100 goniometer .Literature results showed that osseointegration is the main parameter for the success of dental implants, which means a protein and bone cell attachment on the implant surface . This atTwo electrochemical analyses were carried out to evaluate the adhesion of the coating on sample surfaces and to analyze the influence on corrosion resistance. The first electrochemical testing was the evolution of the open circuit potential (OCP), which was monitored for 3600 seconds. The second performed testing was potentiodynamic polarization to obtain the polarization curves. For potentiodynamic polarization, a sweep rate of 0.001 V/s and potentials of −0.500 V to 1 V were used. The electrolyte was a physiological solution containing 0.9% of NaCl at room temperature. The equipment used was an AUTOLAB potentiostat/galvanostat . The cell used for the analyses consists of a calomel reference electrode, a platinum counter electrode, and the sample disc as the working electrode.The statistical analyses were performed by an ANOVA variance calculation followed by Tukey's test. For statistical analysis, PRISM GRAPH 9  software was used.2O5 particles. Figures 2O5 particles and translucent graphene sheets.Figures Roughness and wettability are important parameters to evaluate the success of dental implants. Hydrophobic surfaces decrease the primary interactions with cells in an aqueous environment. It is usually reported that biomaterial surfaces with moderate hydrophilicity improve cell growth and material biocompatibility .Graphene oxide, obtained by the oxidation of graphite flakes, has hydrophilic characteristics, good dispersion, and compatibility with various polymeric matrices , 13 TitaThe analysis of the simultaneous influence of surface wettability, roughness, and chemical composition on osseointegration is complex. Surface treatments modify the wettability of implants, making them hydrophilic or hydrophobic. Some proteins interact with hydrophilic surfaces, and others interact with hydrophobic ones. Smooth surfaces are suitable for interaction with fibroblasts, and rougher surfaces are suitable for interaction with osteoblasts. As for the wettability, it is possible to estimate the relationship between the surface energy and the contact angle. There is an inversely proportional relationship between the two properties, regardless of whether the samples have micrometer (Ti G4) or submicrometer (Ti Hard) grain size .Cell adhesion and scattering occur on surfaces with moderate wettability and contact angles between 50° and 80°. The fixation and proliferation of osteoblasts increase as the surface wettability increases , 17. TheClassifying surfaces as hydrophilic or hydrophobic is not enough to determine a good relationship between the material surface properties and cellular adhesion and to analyze the possibility of implant osseointegration . The infμm. Samples coated with niobium pentoxide had Ra 0.44 ± 0.03 μm. The samples coated with graphene oxide had Ra = 0.47 ± 0.04 μm. Statistical analysis showed no statistically significant difference among three of the four groups studied. The cp Ti-NBGO group had the highest average roughness (Ra = 0.64 ± 0.47 μm), which represents a statistically significant difference from the other groups.The Ra parameter is most used in the literature to characterize the surface roughness of dental materials and applies to most manufacturing processes. Among the disadvantages of using the Ra value, we highlight the fact that this parameter only quantifies the average roughness. It makes no distinction between peaks and valleys and does not define the shape of the irregularities. For this reason, in the present work, the roughness measurements were complemented by the RMS and Rz parameters. The RMS value corresponds to the square root of the mean of the squares of the ordinates, that is, the root means square deviation. The Rz parameter corresponds to the arithmetic mean of five values of the distances between peaks and valleys. These parameters were quantified to analyze the influence of coatings on surface roughness, which act directly on the cell's adsorption of micrometric surface characteristics .The cell interaction with the implant surface is influenced by topography at macroscopic levels and roughness at the microscopic level. Increasing the surface area of the implant increases the number of possible sites for cell attachment, facilitates tissue growth, and increases mechanical stability. However, this is not a general rule. The level of roughness must be controlled because the cells need anchorage points on the implant surface to initiate proliferation and ensure mechanical stability. When the surface has a roughness much smaller than the cells' sizes, there may be an absence of adhesion sites. On the other hand, if the implant has a larger quantity of small peaks or valleys, the surfaces may be smooth and the cells, likewise, cannot be fixed .μm have better osseointegration and mechanical stability than smooth or rougher surfaces. Implants with surface roughness between 0.8 and 1.5 μm and with nanoroughness have the best success rates [Dental implant surfaces with Ra between 0.8 and 2.0 ss rates . Possiblss rates  Some celss rates . On a smss rates .μm and a removal torque of 62.08 N·cm. Implants with Ra = 1.51 μm are removed with a torque of 66.56 N·cm. The implant with greater Ra (1.0 μm) needs a torque of 76.45 N·cm to be removed. These results show that osteoblasts have a better affinity for surfaces with medium roughness (Ra = 1.0 μm) [In vivo tests with rabbits showed that machined implants without surface treatment have Ra = 0.32 ± 0.03  1.0 μm) .Considering that RMS is the standard deviation of Ra, it can be said that the values of Ra and RMS are complementary. The deposition of graphene on metal surfaces forms a protective barrier that increases the corrosion resistance  and the 2O5 may be associated with the lower stability of niobium oxide than titanium oxide, which is confirmed by the Ellingham diagram [2O5 release is the desired effect since it may help osseointegration, increase in cell viability, and the proliferation of osteoblasts [This decrease in corrosion resistance after the deposition of Nb diagram . Howevereoblasts .2O5. This behavior may be associated with lower niobium oxide stability than titanium oxide. However, this Nb2O5 release is the desired effect since it may help osseointegration, increase in cell viability, and osteoblast proliferation [Based on the Ellingham diagram , it is pferation .2) than without coating cp Ti (51.61 ± 4.49 mJ/m2), cp Ti-NB (40.80 ± 13.47 mJ/m2), and cp Ti-NBGO (46.10 ± 6.38 mJ/m2). These surface energy values are adequate for protein and cell adhesion.Wettability measurements showed that the Ti samples coated with graphene oxide (cp Ti-GO) had lower surface energy (12.94 ± 9.33 mJ/mμm, niobia coated samples had Ra = 0.44 ± 0.03 μm, graphene oxide coated samples had Ra = 0.47 ± 0.04 μm, and samples coated with both niobia and graphene oxide had Ra = 0.64 ± 0.47. Statistical analysis of the roughness parameters showed no statistically significant difference among samples from the first three groups and a significant difference with the last group.Roughness measurements showed that uncoated samples had Ra = 0.52 ± 0.06 2O5 coating decreases corrosion resistance, and the coating with both materials may be beneficial since the release of Nb2O5 helps in osseointegration, increasing cell viability, and proliferation of osteoblastsThe anodic potentiodynamic polarization curves show that the graphene oxide coating increases corrosion resistance, the NbBased on experimental results, it is possible to conclude that