Terahertz reflection behaviors of metallic-grating-dielectric-metal (MGDM) microcavity with a monolayer graphene embedded into the dielectric layer are theoretically investigated. A tunable wideband reflection dip at about the Fabry–Pérot resonant frequency of the structure is found. The reflectance at the dip frequency can be electrically tuned in the range of 96.5% and 8.8%. Because of the subwavelength distance between the metallic grating and the monolayer graphene, both of the evanescent grating slit waveguide modes and the evanescent Rayleigh modes play key roles in the strong absorption by the graphene layer. The dependence of reflection behaviors on the carrier scattering rate of graphene is analyzed. A prototype MGDM-graphene structure is fabricated to verify the theoretical analysis. Our investigations are helpful for the developments of electrically controlled terahertz modulators, switches, and reconfigurable antennas based on the MGDM-graphene structures. The three theoretical methods are combined to explore the reflection behaviors of the MGDM-graphene structure and their dependences on the parameters of mobility and carrier concentration of graphene.n manner . In thisn manner ,(3)C was deposited on a Si substrate by using a magnetron sputtering growth system (Denton Discovery 24) with a base pressure of 10−6 Torr. Ti (99.99% purity) and Au (99.99% purity) sputter targets were used. During the deposition, the anode bias is 160 V and the cathode current is 5 A. Second, a 9-μm thick BCB dielectric layer was deposited on the bottom mirror. A commercial BCB precursor  was spin-coated on the metallic mirror using 500 rpm for 10 s followed by 2000 rpm for 30 s, and the standard temperature–time diagram provided by the product manufacturer was used to carry out the thermal curing in a closed chamber full of nitrogen gas (99.9% purity). A step profiler  was used to test the thickness of the BCB layer. Third, a standard PMMA-assisted transfer procedure of CVD-growth graphene to the 9-μm thick BCB layer was processed. The wafers of CVD-grown single-layer graphene on copper foil were purchased from MukeNano . The nominal mobility is 2500 cm2/s/V. Raman scattering measurements  were performed to characterize the crystal quality of the transferred graphene sheet. Fourth, on the graphene sheet, a 1-μm thick BCB layer was deposited. Another commercial BCB precursor  was spin-coated on the metallic mirror using 500 rpm for 10 s followed by 5000 rpm for 30 s. The corresponding temperature-time diagram  was used to thermally cure the BCB layer. Finally, the 15 nm/500 nm thick Ti/Au metallic grating was made on the top BCB layer by using the standard photolithography and lift-off processes.The MGDM-graphene structure is composed of (from the Si substrate) an Au bottom mirror layer, a 9-μm thick BCB dielectric layer, a monolayer graphene sheet, a 1-μm thick BCB layer, and an Au grating layer. The periodicity of the grating is 30 μm. The metal strips are 15 μm wide and 0.5 μm thick. The dimension of the structure is 1 × 1 cm2 dielectric layer, the uncontrollable bulk free-carrier loss is negligible for the BCB dielectric layer, which will reduce the insertion loss effectively. Finally, the graphene layer is encapsulated in the chemically stable dielectrics, which prevents the graphene sheet from the extra residual impurities introduced during the fabrication of metal periodic structures and the deleterious effects of the environment.The basic principle of the MGDM-graphene is similar with the reported absorbers and modulators ,44 worki−1 related to the crystal defects in graphene, which indicates the good quality of the transferred graphene. The ratio of peak magnitudes of 2D (2670 cm−1) and G (1580 cm−1) is about 2.65. Such a high 2 D/G ratio is the signature of monolayer graphene sheet [μ = 1500 cm2/s/V and n = 7.0 × 1012/cm2) with incident angles of 0° and 11° are presented in zk is the wavevector in z direction, L is the thickness of the MGDM cavity, π and Gratingφ are the additional reflection phases at the bottom metallic mirror and the grating interface, respectively, and k is an integer. The wavevector zk can be expressed askx0 is the x-component of wavevector and M = 0, ±1, … is the grating diffractive mode number. The first dip at 3.35 THz corresponds to the resonant mode k = 1 and M = 0. The wavelength of the first dip at 3.35 THz is, minλ = c/(nBCB × minf) = 55 μm with c the speed of light in vacuum, BCBn the refractive index of BCB, and minf = 3.35 THz, which is longer than 4L = 40 μm. Such a discrepancy originates from the reflection additional phase at the grating layer Gratingφ at the resonant frequency. Because of the field constructive interference near the grating interface, the intensity of the local electric field increases, which enhances the graphene-induced absorption loss and leads to the reflection dip at 3.35 THz.The reflection spectrum of the MGDM-graphene device is measured using a Fourier transform infrared spectrometer . In order to eliminate the influence of water vapor absorption, the sample chamber of the spectrometer is evacuated. A reflection module (Bruker A510/Q) with a fixed incident angle of 11° is utilized to measure the reflection spectrum. A linear polarizer is inserted into the optical path between the radiation source and the sample to obtain the p-polarized wave . A numerical fitting procedure is carried out by using the commercial COMSOL software with carrier mobility and carrier concentration of graphene as the fitting parameters. The experimental reflection spectrum and the numerical reflection spectra .At frequency range larger than 5.0 THz, there exists big discrepancies between simulation and experiment. For the grating with 30 μm periodicity, the frequency of the first-order diffractive mode in the BCB layer is 6.2 THz. Thus the reflection features located above 6.2 THz are related to the first-order diffractive modes μ = 1500 cm2/s/V. The numerical reflectance using different methods  at the first dip as a function of carrier concentration is presented in M = 1, 2, …, 5) and the number of the Rayleigh modes in the dielectric layer is 35 . The MM results are in good agreement with the rigorous FEM results, which verifies the validity of the method and the correctness of our homemade code. The numerical results shown in R(n) = R0 + Aexp(−n / n0) with fitting parameters R0 = 0.085, A = 0.88, and n0 = 2.1 × 1012/cm2, from which the numerical MD can be derived as MD = A / (A + R0) = 91.2% and the insertion loss is 1 − A − R0 = 3.5%. 12/cm2, respectively. The FEM and MM results are in good accordance with each other. With increasing carrier concentration, the shape of the dip remains unchanged, but the peak frequency is blue shifted.For the MGDM-graphene structure, the reflection behaviors can be well understood with the concept of impedance matching or critical absorption. Thus the ECM is a valuable tool to analyze the reflection spectra of the structure and gain deeper understanding on the physical mechanisms behind such behaviors. In our calculations, as shown in 12/cm2 are shown in μ < 1500 cm2/s/V. However, such a relation of reflectance with carrier mobility is inverse when μ > 1500 cm2/s/V. As shown in 12/cm2), the values of the resistor and the inductor are determined by carrier mobility. Therefore, an optimal value of carrier mobility exists that satisfies the critical impedance matching condition. In our calculations, when μ > 3500 cm2/s/V, another shallower reflection dip emerges at 1.4 THz. z component) distributions for μ = 1500 cm2/s/V at the dip frequency of 3.35 THz and μ = 7500 cm2/s/V at the dip frequencies of 1.4 THz and 3.35 THz. The field distributions clearly show that the graphene surface plasmon (SP) modes are excited by the evanescent modes localized near the strip edges. The wavevector of the SP modes can be expressed as [v = c/ε1/2 is the speed of light in the dielectric and γ = 1/τ is the scattering rate. Equation (8) indicates that the loss of SP modes proportional to the imaginary part of SPk that is more dominant at lower frequencies. Therefore, because of the large loss, the reflection dip at 1.4 THz cannot be resolved for lower carrier mobilities. Carrier mobility is a key parameter to determine the electromagnetic properties of graphene. The FEM-based numerical reflection spectra with different carrier mobilities and a fixed carrier concentration of 7 × 10essed as .(8)kSP=Generally, in a metal-graphene hybrid structure, the space between the graphene sheet and the metallic array must be kept in deep subwavelength scale to maintain a stronger light–graphene interaction. In this case, the near-field interaction, in other words, the effects of evanescent-mode-excited SP modes propagation along the graphene sheet cannot be appropriately treated by the ECM, even in the frequency range that the wavelength is much longer than the periodicity of the metallic array. In recent years, several multi-mode ECMs  are deven = 7 × 1012/cm2 and μ = 7500 cm2/s/V calculated by the MM with different numbers of waveguide modes and Rayleigh modes. At the dip frequencies of 1.4 THz and 3.35 THz, only the fundamental waveguide mode and Rayleigh mode are the propagating modes. However, due to the deep subwavelength space between the metallic grating and the graphene sheet, the evanescent modes play key roles in the shape and reflectance of the reflection dips. As shown in N = 15 (31 Rayleigh modes being used to expand the electromagnetic fields in the upper and lower regions of the grating), there is a large difference between the numerical reflection spectra with M = 1, 3, and 5. Because of the small difference between the cases of M = 3 and M = 5, it is expected that the calculations are convergent when M > 5. N = 0, 2, 10, and 15 and a fixed waveguide mode number of M = 5. For the cases of N= 10 and N = 15, the two reflection spectra are completely overlapped. The above results indicate that the MM calculations are convergent when M > 5 and N > 10.n = 7 × 1012/cm2 and μ = 1500 cm2/s/V. This work is helpful for the developments of electrically controlled terahertz modulators, switches, and reconfigurable antennas based on MGDM-graphene structures.In conclusion, reflection spectra of a MGDM-graphene structure in terahertz regime are systematically investigated. The rigorous finite element method , the modal method, and the equivalent circuit model are utilized to study the reflection behaviors of the MGDM-graphene structure. A reflection dip near the Fabry-Pérot resonant frequency of the MGDM-graphene structure is found. The reflectance of the dip is very sensitive to the carrier concentration in the graphene sheet, which indicates that the structure can be used as modulators. The calculated modulation depth can reach 91.2% with a small insertion loss of 3.5%. There exists an optimal value of carrier mobility for obtaining the maximum modulation depth. The reflection behaviors and their dependences on the graphene parameters, carrier mobility and carrier concentration, can be qualitatively understood with the concept of impedance matching. Indeed, the results based on ECM can qualitatively describe the behaviors of the reflection dip. However, because the distance between the metallic grating and the graphene sheet is in deep subwavelength scale, near-field interactions play key roles in the reflection of the MGDM-graphene structure. The calculations based on MM quantitatively show the effects of high-order evanescent waveguide modes and Rayleigh modes, especially for the case of high carrier mobility. These near-field effects cannot be correctively treated by the ECM-based calculations. A prototype MGDM-graphene structure is fabricated. The experimental reflection dip near the Fabry-Pérot resonant frequency can be well reproduced with the fitting parameters of


Tissue engineering is an interdisciplinary field that combines principles of engineering and life sciences to obtain biomaterials capable of maintaining, improving, or substituting the function of various tissues or even an entire organ. In virtue of its high availability, biocompatibility and versatility, cellulose was considered a promising platform for such applications. The combination of cellulose with graphene or graphene derivatives leads to the obtainment of superior composites in terms of cellular attachment, growth and proliferation, integration into host tissue, and stem cell differentiation toward specific lineages. The current review provides an up-to-date summary of the status of the field of cellulose composites with graphene for tissue engineering applications. The preparation methods and the biological performance of cellulose paper, bacterial cellulose, and cellulose derivatives-based composites with graphene, graphene oxide and reduced graphene oxide were mainly discussed. The importance of the cellulose-based matrix and the contribution of graphene and graphene derivatives fillers as well as several key applications of these hybrid materials, particularly for the development of multifunctional scaffolds for cell culture, bone and neural tissue regeneration were also highlighted. In recent decades, the rapidly aging population, environmental stressors, frequent cases of traumatic injuries and chronic diseases lead to a growing interest in the revolutionary domain of tissue engineering (TE) ,2,3. TisPorous three-dimensional (3D) scaffolds are an important component of tissue engineering. These constructs are used to provide an appropriate environment for tissue and organs regeneration. Biological scaffolds  are an accessible option because they already contain a broad spectrum of signaling molecules with an important role in the processes of cellular morphogenesis and function development ,12. HoweCellulose remarks itself among the biomaterials used for scaffold production due to its high availability and renewability. Cellulose is mainly extracted from plant cell walls. The nano-scaled forms of plant cellulose—cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), are obtained following specific mechanical and chemical treatments  ,19. In vCellulose can also be produced by certain microorganisms, in this case being called bacterial cellulose (BC). BC is considered to be the most biocompatible form of cellulose because it lacks biogenic impurities such as lignin and hemicellulose and only mild chemical treatments are required to ensure its purity . The nanPure cellulose lacks solubility in common organic solvents. This represents an issue when it comes to processing techniques where a stable polymeric solution is required to prepare the final material . Cellulose was dissolved so far only in mixtures of highly toxic solvents  ; howeverGraphene (GE) is an allotrope of carbon produced by top down  or bottom up techniques  . GE has 2SO4 in a microwave device. The material was kept at 180 °C and a pressure of 40 bar, for 2 h, under nitrogen flow. Following this treatment, black solid carbon spheres were obtained. The spheres were further dispersed in concentrated nitric acid (HNO3), ultrasonicated 30 min at 45 °C and heated at 90 °C for 30 min, under magnetic stirring to obtain nGO. The ultrasonication time is a decisive factor in obtaining materials with uniform and reproducible properties . . 112]. TIn another study conducted by Kumar et al., GO nanosheets and CNCs were employed as multifunctional crosslinking agents for polyacrylamide-sodium carboxymethyl cellulose (PAA-NaCMC) hydrogels, prepared by in situ free radical polymerization. Due to GO and CNCs hydrophilic nature and ability to provide sites for hydrogen and covalent bonding, both PAA and NaCMC had favorable molecular interactions with GO and formed strong interfacial bonds with CNCs. The synergistic effect of GO and CNC lead to an improvement of the viscoelastic mechanical properties, shape recovery behavior and self-healing ability of the interpenetrating PAA/NaCMC network. Still, further studied must be conducted in order to determinate if these hybrid hydrogels represent appropriate 3D microenvironments for tissue engineering applications .Polylactic acid is a biobased plastic obtained by bacterial fermentation processes. Its biodegradability and biocompatibility recommend it for replacing conventional petroleum-based plastics used in the biomedical field. Still, its mechanical properties need further improvement. CNCs and rGO were used as reinforcing fillers for PLA ,62. The This study suggests that rGO is not only a reinforcing agent for biopolymer matrices but can also induce an antimicrobial character, very useful for preventing infections in tissue engineering applications.Undeniably, cellulose and graphene are highly versatile materials and they can be employed in multiple ways to obtain hybrid composites with superior physico-chemical and biological features compared to cellulose or graphene alone. A summary of the cellulose/graphene composites for tissue engineering applications presented in the previous chapters is found in This review highlighted some of the recent discoveries regarding cellulose-based composites with graphene and graphene derivatives. As most of the described studies concluded, the combination of cellulose and graphene renders sustainable and cost effective composites with improved physico-chemical features and bioactivity. Cellulose and graphene can be labeled as complementary materials because the incorporation of graphene in cellulose-based matrices minimizes GE’s potential cytotoxic character and, in its turn, GE improves the biocompatibility of cellulose by providing cell binding sites and positively interfering in cellular differentiation processes and also its mechanical properties. The versatility of both cellulose and graphene is another important reason cellulose/graphene composites are needed in tissue engineering. Cellulose paper was used to develop electrodes for cellular electrical stimulation or in vivo tissue models for a better understanding of a specific tissue biology and experimental drug testing. Bacterial cellulose and cellulose derivatives were employed in the form of electrospun mats, membranes, and hydrogels as ECM-mimicking scaffolds for enhanced cell adhesion, growth and proliferation whereas cellulose nanocrystals and cellulose nanofibers were incorporated in various biopolymer matrices for a reinforcing effect. Some particularly interesting features for tissue engineering are related to GE and its derivatives ability to guide stem cells differentiation toward specific lineages  and also to the electrical conductivity and fluorescent properties that they provide to cellulose matrices, thus extending the areas of application of cellulose/graphene composites Also, a synergistic reinforcing effect was observed when both cellulose and graphene-based fillers were incorporated in various biopolymer matrices.The constant research activity in the field of cellulose/graphene composites lead so far to important discoveries in the area of tissue engineering. Even if these materials could represent promising alternatives to currently used medical techniques, the progress toward obtaining clinical products is slow. Future trends consist of the collaboration of clinicians, biomaterial scientists and engineers, with expertise in their own fields, to elaborate marketable and accessible products for therapeutic purposes.


Sarcoidosis is a systemic granulomatous disease caused by CD4+ cell-dominant inflammation. Meanwhile, diffuse panbronchiolitis is a chronic inflammatory respiratory disease predominantly caused by CD8+ lymphocytes and neutrophils. Herein, we report a rare case of sarcoidosis in which the clinical presentation had become evident as diffuse panbronchiolitis after splenectomy for sarcoidosis.Hemophilus influenzae. The titer of cold agglutinin was elevated, thereby confirming the diagnosis of diffuse panbronchiolitis. On the basis of the clinical and radiological findings, the condition of the patient improved with low-dose macrolide therapy for 3 months.A 23-year-old Japanese woman was referred to our hospital due to splenomegaly of unknown etiology. Upon admission, chest computed tomography scan revealed centrilobular and randomly distributed small nodules in both lungs. Bronchoalveolar lavage revealed a high proportion of lymphocytes and a decreased CD4/CD8 ratio. However, the biopsy specimens obtained from both the liver and lungs revealed noncaseating epithelioid granulomas, which confirmed the diagnosis of sarcoidosis. The patient underwent splenectomy due to progressive cytopenia and high risk of splenic rupture. After the surgery, the condition of the patient was consistently good for 3 months. Then, she gradually developed productive cough and dyspnea. Both sinus and chest computed tomography scan revealed chronic paranasal sinusitis and deterioration of centrilobular nodules in both lung fields, respectively. The second bronchoalveolar lavage revealed a high proportion of neutrophils, and the bronchoalveolar lavage fluid tested positive for The coexistence of sarcoidosis and diffuse panbronchiolitis has not been previously reported, and the hidden profiles of diffuse panbronchiolitis may have been revealed by splenectomy. Sarcoidosis is a systemic granulomatous disease of unknown etiology. The lungs and intrathoracic lymph nodes are the commonly affected regions, and the liver and spleen are the most commonly affected extrapulmonary organs , 2. A hiHemophilus influenzae or Pseudomonas aeruginosa.Meanwhile, diffuse panbronchiolitis (DPB) is a chronic inflammatory respiratory disease predominantly affecting East Asians . The typThe mechanisms of these two respiratory diseases are different, and the coexistence of sarcoidosis and DPB has not been observed in previous studies. Herein, we report a case of sarcoidosis in which the clinical presentation had become evident as DPB after splenectomy for sarcoidosis.A 23-year-old Japanese woman was referred to our hospital due to splenomegaly of unknown etiology and cytopenia. Before referral, she underwent intensive examinations, including bone marrow aspiration and spleen biopsy, at other medical care centers for the detection of hematologic, endocrine, and hereditary diseases in a differential diagnosis. However, a definitive diagnosis was not made. Upon admission, the patient presented with dyspnea upon exertion and abdominal distention. Chest CT scan revealed the presence of both centrilobular and randomly distributed small nodules in both lungs Fig. a. In addHemophilus influenzae. In addition, the cold agglutinin test had positive results, and paranasal sinus CT scan revealed inflammation of the maxillary sinus (Fig. The patient complained of gradually exacerbating dyspnea and increase in purulent sputum 3 months after splenectomy. Chest CT scan revealed the presence of centrilobular nodules with bronchial wall thickening in both lung fields Fig. . The bacnus Fig. e. Becausnus Fig. .Fig. 3aHerein, we report the coexistence of sarcoidosis and DPB, which became evident after splenectomy. The diagnosis of sarcoidosis was confirmed on the basis of the presence of noncaseating granulomas in the biopsy specimens obtained from several organs, including the liver, spleen, and lungs. Increased lymphocyte count in the BALF is commonly observed in patients with sarcoidosis; the CD4+ lymphocytes infiltrate into the alveoli, causing the high CD4/CD8 ratio in the BALF , 2. HoweHemophilus influenzae. Since splenectomy is a risk factor for infectious diseases caused by Hemophilus influenza, it may explain the exacerbation in DPB.Splenectomy might have triggered the exacerbation of DPB. The levels of serum ACE and lysozyme, which reflect the disease activity of sarcoidosis, decreased after splenectomy. By contrast, the presence of centrilobular nodules, which is one of the radiological features of DPB, was found on chest CT scan in the current case. Furthermore, the second BAL revealed both increased proportion of neutrophils and a positive bacterial culture for In the present case, the histological features of DPB were also confirmed; biopsy specimens obtained during the first bronchoscopy showed accumulation of foamy cells around the respiratory bronchioles where the distinctive feature is observed in patients with DPB . The detIn conclusion, the present case highlighted the complex presentation of the coexistence of sarcoidosis and DPB. If a patient with sarcoidosis presents with an atypical disease presentation, the coexistence of other diseases should be considered.


Exploring the relationships between free-living (FL) and particle-attached (PA) bacterial communities can provide insight into their connectivity and the partitioning of biogeochemical processes, which is crucial to understanding the elemental cycles and metabolic pathways in aquatic ecosystems. However, there is still intense debate about that whether FL and PA fractions have the same assemblage. To address this issue, we investigated the extent of similarity between FL and PA bacterial communities along the environmental gradients in Lake Wuli, China. Our results revealed that the west Lake Wuli was slightly eutrophic and the east lake was moderately and highly eutrophic. The alpha-diversity of the FL bacterial communities was significantly lower than that of the PA fraction in the west lake, whereas the alpha-diversity of the two fractions was comparable in the east lake. The beta-diversity of both communities significantly differed in the west lake, whereas it resembled that in the east lake. Moreover, functional prediction analysis highlighted the significantly larger differences of metabolic functions between the FL and PA fractions in the west lake than in the east lake. Suspended particles and carbon resource promote the similarity between the FL and PA fractions. Collectively, our result reveals a convergent succession of aquatic communities along the eutrophic gradient, highlighting that the connectivity between FL and PA bacterial communities is nutrient related. Particles are crucial components in aquatic ecosystems , servingExploring the relationships between the FL and PA bacterial communities has been of long-standing interests to microbiologists. For decades, the FL and PA bacterial communities have been considered to be significantly different. The PA lifestyle has considerable advantages over the FL lifestyle, including access to resources and protection from predators and deleterious environmental pressures . FurtherHowever, many updated and novel findings show only slightly different FL and PA bacteria communities . Modern Thus, any attempt to understand the aquatic communities must be placed in the context of the relationship between the FL and PA bacterial communities. Recent progress has found that the aquatic communities prefer an FL lifestyle when nutrient level is high, whereas they prefer a PA lifestyle when nutrient level is low . Thus, w2  in the north of Lake Taihu, China. Lake Wuli has an area of 8.6 km2  and is d2 . Since t2 . Since 22 , most arproducts . Being lproducts .Microcystis on the surface of Lake Wuli. In this case, 5 μm pore size is adequate to collect the PA bacteria . Eight additional characteristics were measured by standard methods (a (Chl-a).Secchi depth (SD) was determined by using a Secchi disk. Water temperature (Temp) and dissolved oxygen (DO) were assessed  methods : total n® cycle-Pure kit (Omega Bio-Tek). The V4 regions of the 16S rRNA genes were amplified using the primers 515F (GTGYCAGCMGCCGCGGTAA) and 806R (GGACTACNVGGGTWTCTAAT) (2 (25 mmol/L), 0.5 μl of each primer (10 μmol/L each), 30 ng of quantified template DNA measuring by Pico green, and 0.4 μl of Taq polymerase . To increase specificity and sensitivity during gene amplification, the touchdown PCR was conducted in a thermocycler : denaturation at 94°C for 5 min, 11 cycles of denaturation at 94°C for 1 min, annealing at 65°C for 1 min (temperature was decreased by 1°C every cycle until 55°C was reached), and extension at 72°C for 1 min  . Polymeror 1 min . NineteeThe pair-end sequencing was performed on an Illumina MiSeq platform. Unique barcodes were added to each sample, and the individual paired reads were initially merged by using FLASH (Fast Length Adjustment of Short reads) software . We remoCRA002048, which is publicly accessible at https://bigd.big.ac.cn/gsa.The raw sequence data reported in this paper have been deposited in the Genome Sequence Archive  in BIG Data Center (Nucleic Acids Res 2019), Beijing Institute of Genomics (BIG), Chinese Academy of Sciences, under accession number 1.All statistical analyses and visualization were carried out using ape, factoextra, gglot2, Hmics, and vegan packages in the R environment (version 3.2.2)kmeans function and were visualized by the fviz_cluster function.As an indicator for assessing the trophic level according to the national standard, the trophic level index (TLI) is presented . The TLIalpha_div and beta_div workflow according to usearch. We calculated four indices: Chao1, Richness, Simpson, and Shannon. To compare the statistical differences, we performed non-parametric Kruskal–Wallis rank tests. We also used non-metric multidimensional scaling (NMDS) analysis on the basis of four distance matrices: Bray–Curtis distance, Jaccard dissimilarity, and unweighted and weighted UniFrac distance. To determine significant difference of beta-diversity, ADONIS was used. To predict the functional profiles of bacterial communities, on the basis of gene bacterial community, we applied the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt)  . To perfOur results showed that the west lake and the east lake were distinct aquatic environments with statistically significant differences. Cluster analysis revealed that samples within the west lake and the east lake were separated from each other . We used-a was significantly lower in the west lake than in the east lake . The SD significantly decreased from 0.78 ± 0.06 m in the west lake to 0.29 ± 0.12 m in the east lake, whereas the TSS significantly increased from 14.83 ± 3.70 to 27.38 ± 4.64 mg/L (both P = 0.002). Water in the west lake contained more oxygen than that in the east lake . Of particular note was that the concentration of six nutrients significantly increased from the west lake to the east lake, namely, TN, TP, TDN, TDP, COD, and DOC .The concentration of Chla. In contrast, the number of OTUs exclusive to the PA bacteria decreased from the west lake to the east lake, with significantly negative correlations with TSS, DOC, COD, and Chl-a , however, in the east lake, the FL and PA fractions were as diverse as each other  (P < 0.01). In contrast, in the east lake, the difference between FL and PA fractions was insignificant . Together, the FL and PA bacterial communities exhibited a convergent succession from the west to east lake. To detect the potential factors influencing the similarity between these two communities, we used the linear fitting approach. High and significantly negative associations are found between their similarities and DOC, COD, TSS, and Chl-a (P < 0.05).After the sequencing depth to the least number of reads among each site  was normalized, four indices were chosen to represent the community alpha-diversity, namely, Chao1, Richness, Simpson, and Shannon. In the west lake, the FL fraction was significantly less diverse than the PA fraction  . The bet > 0.05) . The resP = 0.006), whereas seven others were lower in the FL fraction than in the PA fraction  (P = 0.04), with Actinobacteria being higher in the FL communities and Chloroflexi being higher in the PA communities  . Howevermunities .P < 0.05), whereas in the east lake, only two classes differed between the fractions (both P < 0.05) (P < 0.05). Furthermore, in the west lake, some anaerobic bacteria, such as Clostridium and Romboutsia, were significantly enriched in the PA bacterial community relative to FL counterpart. However, in the east lake, the anaerobic bacteria of the FL and PA communities were comparable with each other.At the finer taxonomic level, 30 class-level taxonomic groups were detected for the two bacterial communities ; both ba < 0.05) . At the  < 0.05) , most ofP < 0.05). In total, the KOs were clustered into 41 gene families, most of which belonged to membrane transport (14.24 and 12.62%), amino acid metabolism (12.63 and 12.19%), carbohydrate metabolism (12.14 and 12.40%), and signal transduction (7.19 and 8.16%) for FL and PA fractions, respectively. In the west lake, 68 KOs were significantly higher in the FL fraction than in the PA fraction, whereas 137 KOs were significantly higher in the PA fraction relative to the FL fraction. In the east lake, 11 KOs were significantly higher in the FL fraction than in the PA fraction, whereas 14 KOs were significantly higher in the PA fraction relative to the FL fraction.Based on the predicted bacterial Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, 276 KEGG orthology groups (KOs) were obtained in the FL and PA bacterial communities, among which 205 and 25 KOs significantly differed in the west lake and the east lake, respectively  , amino acid metabolism , metabolism of other amino acids (mainly glutathione metabolism and phosphonate and phosphinate metabolism). In contrast, 16 gene families were significantly higher in the PA fraction than in the FL fraction  (starch and sucrose metabolism and amino sugar and nucleotide sugar metabolism), glycan biosynthesis and metabolism (mainly lipopolysaccharide biosynthesis and other glycan degradation), energy metabolism (mainly methane metabolism and sulfur metabolism), and signal transduction (mainly two-component systems). In the east lake, 14 gene families showed significantly higher relative abundance in the FL fraction than in PA fraction  (P < 0.05)  , includi < 0.05) , includi < 0.05) . In cont < 0.05) .Because FL bacteria and PA bacteria occupy different ecological niches, exploring their relationships sheds light on the nutrient cycles and major metabolic pathways in aquatic ecosystems. Some previous studies have demonstrated that FL and PA bacteria are significantly different from each other , whereasOur results showed that Lake Wuli could be divided into two significantly distinct aquatic regions: the east lake with slight eutrophication and the west lake with moderate eutrophication and hyper-eutrophication. The FL bacterial communities were less diverse than the PA fraction in the west lake, whereas they were as diverse as each other in the east lake. Furthermore, both compositional structures and metabolic functionalities of the FL and PA communities were significantly different in the west lake but become similar in the east lake. Thus, the FL and PA bacterial communities showed a convergent succession along the eutrophic gradient from the west lake to the east lake. Recently, an increasing body of evidence has shown that nutrient enrichment leads to biotic homogenization in aquatic habitats, including insects , macroinFor decades, aquatic bacteria have been artificially categorized into two distinct lifestyles: FL and PA . Howevertwo-component system in PA bacterial communities from the west lake to the east lake. This signal transduction pathway controls bacterial cell attachment to the substrate surface, which facilitates biofilm formation .The sequencing data generated by this study can be found in the BIG Nation Genomics Data Center (YH and GG conceived and designed the experiments. GX and XJ performed sample collection. KS and XT analyzed the data. YH wrote the manuscript. All authors have read and approved the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


L1 is based on the guanidiniocarbonyl pyrrole cation and serves as a highly specific anion binder in order to target the interaction between Survivin and Histone H3. NMR titration confirmed binding of L1 to Survivin's Histone H3 binding site. The inhibition of the Survivin–Histone H3 interaction and consequently a reduction of cancer cell proliferation were demonstrated by microscopic and cellular assays.The protein Survivin is highly upregulated in most cancers and considered to be a key player in carcinogenesis. We explored a supramolecular approach to address Survivin as a drug target by inhibiting the protein–protein interaction of Survivin and its functionally relevant binding partner Histone H3. Ligand  Effective interruption: The supramolecular guanidiniocarbonyl pyrrole ligand L1 targets the Histone H3 binding site of the protein Survivin, which is highly upregulated in cancer. Inhibiting the interaction between the two proteins successfully reduced cancer cell proliferation. Survivin is overexpressed in almost all malignant tumors and is considered an early diagnostic and prognostic biomarker.The most successful approaches so far have used compounds that display specific, well‐characterized recognition properties for amino acids and peptides in order to functionally modulate PPIs.L1) as the ligand with the best docking score  65 and 68, aspartic acids (D) 70, 71, and 72, and glutamic acids (E) 75 and 76  68, aspartic acid (D) 70, 71, and 72, and glutamic acid (E) 75 . The PLA allows the visualization of protein–protein interactions within cells on an endogenous level. At first, two primary antibodies bind to the target proteins Survivin and Histone H3. Secondary antibodies that are conjugated to a matched pair of short single‐stranded oligonucleotides then recognize these antibodies. If the two targets are in close proximity (<40 nm), the oligonucleotides hybridize and ligate with two additional connector oligonucleotides to form a continuous circular DNA structure. DNA polymerase then amplifies these circular structures through rolling‐circle amplification with fluorescent nucleotides that can be detected as PLA signals with fluorescence microscopy. The PLA indeed revealed a significant decrease of the Survivin–Histone H3 interaction inside the cell upon n Figure  A,B.L1 could be shown to inhibit the interaction between Survivin and Histone H3 inside the cell, we wanted to investigate whether the inhibitor would consequently also interfere with Survivin's role in cell proliferation. Therefore, HeLa cells were treated with 50 μm of L1 and synchronized before they were fixed during mitosis. The cells were then immunostained to allow the microscopic identification of mitotic defects. Cells that displayed mitotic defects were assigned to one of the five following categories: Multipolar Pro‐/Metaphase, Multipolar Ana‐/Telophase, Lagging Chromosomes, Acentric Fragments, and Chromatin Bridges .L1‐treated cells showed a larger variety of mitotic defects in comparison to the control. In addition to acentric fragments and lagging chromosomes, also chromatin bridges and multipolar spindles could be observed  used for this assay is added to the cells and bioreduced into a colored formazan product. The quantity of formazan product measured at 490 nm absorbance is directly proportional to the number of living cells in culture. The assay revealed that L1 was able to successfully inhibit cell proliferation in all cancer cell lines tested ‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2d Figure  C. In thL1 on cancer cell proliferation are Survivin‐specific, we performed a rescue experiment in which we transiently transfected HCT 116 cells with Survivin–HA (Rescue) or with GFP (Control). After treating the cells with L1 for 72 h we measured cell proliferation via an MTS assay. We were able to observe that an overexpression of Survivin–HA nearly completely rescued the antiproliferative effect of L1 in all tested concentrations. While cell proliferation was reduced to 72 % (50 μm), 67 % (100 μm), and 55 % (200 μm) in control cells, cell viability could be restored to 97 % (50 μm), 89 % (100 μm), and 91 % (200 μm) in cells overexpressing Survivin–HA  should be addressed to the authors.SupplementaryClick here for additional data file.


We investigate the intercalation process of oxygen in-between a PVD-grown graphene layer and different copper substrates as a methodology for reducing the substrate-layer interaction. This growth method leads to an extended defect-free graphene layer that strongly couples with the substrate. We have found, by means of X-ray photoelectron spectroscopy, that after oxygen exposure at different temperatures, ranging from 280 °C to 550 °C, oxygen intercalates at the interface of graphene grown on Cu foil at an optimal temperature of 500 °C. The low energy electron diffraction technique confirms the adsorption of an atomic oxygen adlayer on top of the Cu surface and below graphene after oxygen exposure at elevated temperature, but no oxidation of the substrate is induced. The emergence of the 2D Raman peak, quenched by the large interaction with the substrate, reveals that the intercalation process induces a structural undoing. As suggested by atomic force microscopy, the oxygen intercalation does not change significantly the surface morphology. Moreover, theoretical simulations provide further insights into the electronic and structural undoing process. This protocol opens the door to an efficient methodology to weaken the graphene-substrate interaction for a more efficient transfer to arbitrary surfaces. Although proven to be an effective process to obtain complete, high-quality monolayer graphene over polycrystalline copper foils [Over last decade, since the discovery of graphene , many meer foils ,4, the cOne of the most promising protocols for the transfer of metal-grown graphene is the so-called electrochemical delamination method , a simpl60 as a precursor is defect-free and therefore it highly interacts with the Cu substrate [Oxygen intercalation has been previously studied on many different metal surfaces, such as Gr/Ru(0001) ,14, Gr/IIn this work, we report on the oxygen intercalation process applied to PVD grown graphene on polycrystalline Cu substrates. The process has been carried out in a UHV environment in order to have a controlled and pure oxygen exposure, that allows fine tuning and optimization of the different parameters  The process has been studied in detail by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy. In addition, Atomic Force Microscopy (AFM) and Kelvin Probe Force Spectroscopy (KPFS) have been used for topographic and surface potential measurements, respectively.2-10 mbar on different types of Cu substrates, both polycrystalline and single crystals. Commercial 35 μm thick Cu foils were used as polycrystalline substrates. In order to observe differences between the as-grown and the oxygen-intercalated specimens after graphene growth, samples were cut into two pieces (twin samples). One was oxygen-intercalated while the other was used as a reference. Both were characterized by means of the aforementioned techniques. In addition to copper foils, single crystals of Cu(100) and Cu(111) were initially employed to assess the feasibility of the intercalation method with a more controlled system. The surfaces of these substrates were prepared by following a standard cleaning procedure in UHV consisting of successive cycles of argon sputtering and annealing at 800 °C. The substrate temperature was monitored with an optical pyrometer. Commercial fullerene C60 molecules (sigma Aldrich 98% purity) were used as the precursor species for graphene growth on the substrate. The fullerenes were purified for several hours at 500 °C. For graphene growth, the clean Cu substrate was heated to 800 °C and maintained at this temperature. Then, the C60 molecules were sublimated in UHV at a temperature of 450 °C and deposited onto the hot surface during typically 1 h [Graphene samples were grown in a UHV environment with a base pressure of 1 × 103 L , using an oxygen pressure of 1.1×10-5 mbar for the intercalation procedure during 30 min. In order to avoid oxygen desorption from the samples, after completing the intercalation procedure, the oxygen pressure was maintained until the sample was cooled to RT.The oxygen intercalation procedure was carried out in UHV by controlling the incoming oxygen (99.9999% purity) dose with a leak valve. The temperature of intercalation was optimized by testing various samples at different intercalation temperatures of 280 °C, 350 °C, 400 °C, 500 °C and 550 °C, monitored using a K-type thermocouple attached to the heater. In all cases the oxygen dose was set to 20×10in situ with an OMICRON LEED. Subsequently, they were transferred in air to a different UHV chamber, where oxygen intercalation and XPS characterization were carried out. Photoemission experiments were performed with a hemispherical analyzer SPECS Phoiboss 100 MCD-5 with an instrumental resolution of 0.02 eV. Al Kα radiation (1486.7 eV) was employed as X-ray source. The topographic characterization of the samples prior to and after oxygen exposure was performed ex situ with a commercial AFM from Nanotec. The images were acquired in dynamic mode to preserve the integrity of both the samples and the tip. Using the same equipment, Kelvin Probe Force Spectroscopy (KPFS) measurements were performed to determine the surface potential. The tips employed were specially manufactured for KPFS measurements coated with gold nanoparticles (2–3 nm) from Nextip [After oxygen intercalation, an exhaustive characterization was undertaken in order to elucidate the mechanism of the process. The samples were characterized m Nextip . HOPG wam Nextip . Raman mDensity Functional Theory (DFT)-based calculations were performed by using the plane-wave code QUANTUM ESPRESSO , includi3The main objective of this work is to study the oxygen intercalation process in the system formed by PVD graphene on Cu foil samples. With this aim, it was first necessary to determine the best conditions for the intercalation process, which are defined by the temperature range and the minimum oxygen dose. To address this problem, a fast and reliable feedback based on LEED patterns was used. As in polycrystalline samples, grains with different orientation contribute with different spots to the LEED pattern without possibility of precise identification , the use3 L of oxygen, and R45°surface reconstruction, exhibiting two different domains. As it is already known, oxygen exposure on Cu(100) at room temperature and low coverage induces the formation of a c(2×2) superstructure, while at high temperatures the surface reconstructs forming a . Nonetheless, for smaller length scales oxygen differences at the graphene/Cu interface could be found. Additionally, the reproducibility of the KPFS data  single crystal was also monitored by LEED. Thus, after graphene growth the sample was annealed at 400 °C while being dosed with 20×10tructure ,42. Thistructure . The obsPFS data  along thTo verify the surface morphology, the graphene/Cu samples were characterized by AFM prior to and after oxygen intercalation for the Cu (100) and Cu(111) single crystal substrates and the polycrystalline Cu foils. The top panel of Both, the presence of the wrinkles and the ring observed by the LEED patterns indicate that the graphene layer grown on the Cu substrates is polycrystalline (see 3 L) at different temperatures. A temperature increase should enhance oxygen diffusion, and hence promote the intercalation process, although it is important to consider that an excessive temperature could compromise the graphene layer through etching processes. The XPS Cu 2p spectra with exposure temperatures from 280 °C to 550 °C are shown in Once the feasibility of the intercalation method is proved  we focus on the PVD graphene on Cu foil, since this system is the most interesting for future applications. To understand the chemical processes involved in the intercalation approach and for a further optimization of the intercalation conditions, we performed XPS in the regions corresponding to the C 1s, O 1s and Cu 2p emissions. The graphene grown on Cu foil was exposed to the same oxygen dose  in contrast to our procedure based on controlled exposure to pure oxygen. Both differences lead to different doping and un-doping levels of the graphene layer for the as-grown and oxygen intercalated layer, respectively. Interestingly, a previous work in graphene on Cu single crystals reported that the electronic response after oxygen intercalation is different for different orientations of Cu [of 0.068 . A secon3 carbon ,46, whicgligible . As it ireported . This dereported ,47 as wereported ,24,48, ans of Cu . Therefons of Cu ,50. It hns of Cu , and tha3 L) for different temperatures. The curve fit, made by using Voigt profiles, found two components located at 529.8 eV and 530.7 eV. According to the literature, the main peak, at lower BE, corresponds to the contribution of an atomic phase state, i.e., a low-bound state [2O [tate [2O . The absWith the aim of determining the influence of oxygen intercalation on the interaction between graphene and the substrate, Raman spectroscopy was performed ex-situ. 2D) has been correlated with strain in graphene layers. However, its absence in the spectra corresponding to the as-grown sample prevents its comparison with the O-intercalated sample by the use of ω2D vs ωG vectors, often employed to evaluate both strain and charge density in graphene layers [2D appears at an average value of 2718 cm-1, corresponding to a blue-shift of > 28 cm-1 with respect to free-standing graphene [2D, between 15 and 40 cm-1, in CVD-grown graphene on Cu foil [D and ωG values of 1373 and 1608 cm-1, respectively observed in the as-grown sample, also represent a significant blue-shift with respect to free-standing graphene and are coherent with compressive strain. Regarding the G band, in the as-grown sample a broad band profile is observed with ωG ~ 1608 cm-1, albeit with some contribution due to the D’ band. Whereas, in the case of the oxygen intercalated sample, the G-band is much stronger and shifted to a lower average frequency of ωG ~ 1600 cm-1, although more asymmetric with a small shoulder corresponding to the D’ peak at around 1620 cm-1, as previously reported [G and ω2D cannot be explained solely by charge doping and strain [2Dω without affecting the ωG [D, ωG and 2Dω to strain release after oxidation, as mentioned previously, which augment with the growth of the oxide underlayer [2O at 148, 219 and 635 cm-1, and CuO at 273, 327 and 619 cm-1 [2O were found for the 400 °C sample, the oxygen atomic phase state being the main O 1 s contribution. Thus, the main conclusions from the Raman data are that the as-grown PVD graphene is highly strained and strongly interacts with the Cu surface and after oxygen intercalation the graphene layer exhibits characteristics closer to that of free-standing graphene, although retaining a certain level of strain according to the 2Dω values observed, which evidences partial electronic decoupling of the graphene layer from the metal. The data obtained from KPFS measurements -(12 × 4)-MR interfaces; a detailed description of these simulations is found in the supplementary information. The most important result is represented in R45°O@Cu(100)-(12 × 4)-MR interface ) as a function of the energy referred to the Fermi energy (in eV). The PDOS profile for the case of Gr/Cu(100) reproduces a well-formed canonical Dirac cone. Nevertheless, the profile morphology shows a slight asymmetry w.r.t. the center of the Dirac cone from that obtained for free-standing graphene (dashed-black line). The symmetry obtained for the free-standing layer is lost when the substrate is considered, due to several factors: firstly, the non-negligible graphene corrugation arising in this case (around 0.17 Å), with regions where the pristine sp2 hybridization is slightly broken; secondly, the effect introduced in the electronic properties by the cell strain of around a 2% in the graphene; and finally, the non-negligible chemical interaction arising at discrete points in the interface. Importantly, besides the emerging asymmetry, the PDOS profile for the Gr/Cu(100) case exhibits a significant n-doping level developed in the graphene layer due to the charge transferred from the substrate, in excellent agreement with our experimental evidence and literature [In order to endorse the un-doping process that occurs when oxygen intercalates in the graphene/Cu interface, and according to the experimental evidence, we have carried out (DFT)-based calculations of a clean Cu(100) with the missing row reconstruction, named as Cu (100)-12 × 4)-MR surface (MR meaning “missing row” structure), of Gr/Cu(100)-(12 × 4)-MR and of Gr/(terature . From th-MR surfa4In this work, efficient oxygen intercalation between graphene layers grown on Cu by PVD in UHV conditions was reported. The graphene layer preserves its morphology after intercalation. The experimental results evidence the adsorption of an atomic oxygen adlayer on top of the Cu surface with no substrate oxidation. The combination of Raman spectroscopy with the XPS measurements and the KPFS experiments suggest an electronic un-doping of the layer, corroborating the electronic decoupling after intercalation. Theoretical DFT studies show that the system is essentially decoupled before a complete monolayer of oxygen is reached. Therefore, the intercalation method employed was demonstrated efficient to promote electronic decoupling of the graphene layer while retaining the advantages of the growth method. Furthermore, as this decoupling route can be performed immediately after graphene growth, it has the advantage of being an end-to-end process in the same vacuum chamber.https://doi.org/10.1016/j.apsusc.2020.147100.Supplementary data to this article can be found online at Supplementary information


Paper diagnostics are of growing interest due to their low cost and easy accessibility. Conductive inks, necessary for manufacturing the next generation diagnostic devices, currently face challenges such as high cost, high sintering temperatures, or harsh conditions required to remove stabilizers. Here we report an effective, inexpensive, and environmentally friendly approach to graphene ink that is suitable for screen printing onto paper substrates. The ink formulation contains only pristine graphite, water, and non-toxic alkanes formed by an interfacial trapping method in which graphite spontaneously exfoliates to graphene. The result is a viscous graphene stabilized water-in-oil emulsion-based ink. This ink does not require sintering, but drying at 90 °C or brief microwaving can improve the conductivity. The production requires only 40 s of shaking to form the emulsion. The sheet resistance of the ink is approximately 600 Ω/sq at a thickness of less than 6 µm, and the ink can be stabilized by as little as 1 wt% graphite. They have drawn interest because paper is inexpensive, absorbs fluids, can be easily modified, disposed of, and scaled up2. Important applications include diagnosing often neglected tropical diseases, home-based cancer and liver diagnostics, food and water testing, and environmental quality monitoring in developing countries3. As the low cost of these devices is critical to their utility, future paper diagnostics will require inexpensive, non-toxic, and easily processed conductive inks. Currently conductive inks find applications in flexible energy storage materials6, sensors8, antennas9, and electronics11. Metal particle-based conductive inks dominate the market, and although these inks provide high electrical conductivity, they are expensive, often unstable and toxic, and require high sintering temperatures18. To address these challenges there has been a great deal of effort in developing carbon-based, and more specifically graphene-based, inks21. However, difficulties in exfoliating graphite and suspending graphene have made these inks expensive, as evidenced by the cost of commercial graphene-based ink marketed for screen printing exceeding $500 per 10 ml. .Paper diagnostics were first introduced in 2007 as a potential solution to high cost and often inaccessible medical diagnostics8. The second approach uses liquid-phase exfoliation with added stabilizer to keep the graphene suspened23. The GO reduction method addresses the challenge of suspending graphene by adding hydrophilic functional groups to the graphene sheets. This introduces defects but sacrifices the electrical conductivity, which is partially restored by the reduction step25. In addition, the method often used for making GO involves harsh chemical treatment in concentrated sulfuric acid26, and the substrates suitable for GO inks are limited due to the GO reduction process that can require post-print temperatures from 200 to 450 °C28.There are two basic approaches to the use of graphene for conductive inks. The first is to reduce graphene oxide (GO) after printing, either by thermal or chemical treatment. This approach requires harsh oxidation of the graphite, but provides water suspendable material30. This is then followed by further stabilization of the graphene by the addition of chemical binders such as polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), or ethyl cellulose (EC)32. However, this results in the need for annealing at temperature from 250 to 400 °C to remove the non-conductive binders after printing35.The alternative to the reduction of GO is liquid-phase exfoliation. In this approach graphite is tip sonicated, often at high power for several days in high boiling temperature solvents such as N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), or surfactantsAn ideal ink would consist of unoxidized, exfoliated graphene sheets without hard-to-remove suspension agents. Here we report an approach to create such an ink using interfacial trapping. The final inks contain only water, graphene, and alkanes and are prepared by simple shaking for 40 s using a bubble tea shaker. The inks are thus inexpensive and promising for large scale production. Shaking the mixture of water, graphite, and alkane forms viscous water-in-oil emulsions stabilized by exfoliated graphene sheets at the water/oil interface. No toxic chemicals or additional stabilizers are needed. The solvents used can be removed either by drying at 90 °C or by microwaving for 40 s. The inks reported here have a graphite loading of 0.1 g/10 ml, but higher and lower concentrations are also stable.36. Other studies have shown that graphene alone can stabilize emulsions, such as the work of Large et al., where graphite was exfoliated by sonication and used to stabilize water-in-oil emulsions37, and the work of Ogilvie et al. who pre-exfoliated with sonication followed by size selection to produce stabilized emulsions with only few layer graphene38. These emulsions were shown to require low graphene loading. In addition, a recently published study demonstrates that graphene stabilizes water-in-oil emulsions due to the amphiphilic nature of pristine graphene, and that based on DFT calculations dispersive interactions between stacked plates reduces the amphiphilic nature of single flakes, meaning that graphite flakes by themselves cannot stabilize water/oil emulsions39. Other research also supported this idea by successfully forming water-in-hexane emulsions using liquid-phase exfoliated graphene38.Since the exfoliation of the graphite is driven by lowering the interfacial energy of the oil/water interface, once sufficient graphene has been produced to cover the interface, exfoliation does not continue. This results in both graphite and graphene being present at the interface. The presence of graphene, and not just graphite, has been shown by TEM images and Raman spectroscopy10. Values ranged from ~ 2 Ω/sq up to ~ 2 × 105 Ω/sq with a median value of 260 Ω/sq. The variation in these values is at least partially a result of a range of approaches, thicknesses, and conditions used for measuring sheet resistance. All of these inks also contained a stabilizer, often cellulose, that required removal by high temperature annealing, often higher than the autoignition temperature of paper. Our measured sheet resistance of ~ 600 Ω/sq is comfortably in the range of other reported inks, despite the lack of a high energy exfoliation method as was required for all the other reviewed inks. Additionally, the lack of an added stabilizer eliminates the need for high temperature annealing, making our inks an attractive option for paper based electronics.A recent review of graphene based conductive inks compared them in terms of their reported sheet resistance36. The exfoliation is spontaneous and driven by lowering the interfacial energy of oil and water as graphene spreads at the interface40. Shown in Fig. 43.Exfoliating graphite by interfacial trapping relies on graphite not being soluble in either water or oil44. Diluting the ink with additional continuous phase allowed the spheres to be observed under an optical microscope as shown in Fig. Emulsifying the system by shaking or stirring produces new oil/water interfaces. This in turn drives further exfoliation of the graphite as it covers the new interfaces, leading to a water-in-oil emulsion with graphene sheets stabilizing the interface. Figure 48. This would not be expected in the original graphite.Diluting the ink with excess dispersed phase broke the emulsion and resulted in a film of overlapping graphene sheets at the water surface. Transmission electron microscopy (TEM) was used to image this film. Figure Printing with this graphene ink does not involve any modification to the screen-printing stencil. This viscous graphene ink can print into complicated patterns with good resolution as shown in Fig. 36.The rate of emulsion formation in the graphene inks is different than with typical emulsions. Exfoliation of the graphite is not instantaneous, meaning that in some cases there initially is insufficient graphene to stabilize a full emulsion. To study this effect, different graphite loadings were investigated. As shown in Fig. As seen in Fig. At day twelve, all vials were shaken again for 40 s, and vial 1 formed a full emulsion Fig. d. This sIt is important to note, however, that the same emulsion volume could not be achieved without the time gaps between shaking. In Fig. 49. So, graphite exfoliation in the C16 ink is more energetically favorable compared to C7, driving the equilibrium towards exfoliated graphene in the C16 ink system.In addition to the initial loading of graphite, the type of alkane had a significant effect on the rate of emulsion formation. Figure 50. Since the restacking of graphene requires a sheet to move towards either the oil or water phase and away from its minimum energy location, the steeper rise in free energy associated with a sharper interface should inhibit restacking26.Another possible explanation involves the sharpness of the oil/water interface. Moiré patterns shown in Figure 51, meaning that graphene is expected to absorb more strongly C16 than C7. Likewise, computational studies have suggested that as the alkane number increases there is an increase in the desorbing energy between the alkane and graphene52. However, despite the difference in emulsion formation rate between the C7 and C16 inks, both had a similar emulsion droplet size, around 50 μm, and a similar droplet size distribution, as observed by optical microscopy  or profilometryTo address the challenge of surface penetration for our conductivity measurements, the C16 ink was drop cast on a glass slide. The sheet resistance of the ink was found to be approximately 600 Ω/sq. The conductivity was calculated using a thickness value based on the mass of graphene, size of the ink dot on the glass slide, and the density of graphite  or an increasing number of prints (N)That residual C16 was the cause of the high observed resistance was shown by further drying the printed lines. When the lines were dried for a week at 90 °C, the C16 ink resistance was decreased to roughly a third of the original resistance. In addition, the resistance of C16 ink lines was also reduced by roughly 70% after microwaving the printed lines for four cycles of ten second duration, with the results shown in Figure While the lack of conductivity in the C16 inks was a result of low vapor pressure, the reason for the lack of conductivity of the C7 inks at small values of X•N is not as obvious. Visual observation of lines made with C7 suggested that at low print numbers C7 inks were less uniform than C16 inks. Further, as mentioned previously, vials of inks made with C16 appeared to have smooth surfaces while inks made with C7 had uneven or rough surfaces. The presence of aggregates in the C7 ink may cause non-uniform application.2). It was observed that with increasing C7 percentage in the ink, there was a steady decrease in the value of R2, providing evidence that the C7 inks provide less uniform graphene application during screen printing.This non-uniform application was quantified by replotting the data derived from nearly 400 individual measurements in Fig. 2 values in the C16 rich inks and the very poor R2 values in the C7 rich inks was investigated by comparing 1/X and 1/N separately, as shown in Fig. The cause for the less than perfect RHere we demonstrated a graphene-based screen-printing ink prepared by interfacial trapping of untreated graphite using non-toxic chemicals. The ink can be prepared in as little as 40 s by simple shaking of a graphite/water/alkane mixture. In contrast to other approaches, no high energy step such as tip sonication or high shear mixing was involved, only a bubble tea shaker set at 320 rpm. Graphite loading in the ink was as low as 0.01 g/ml with no post-printing procedures requiring harsh chemical treatment or high temperatures as no high boiling point chemical binders or stabilizers were involved in the formulation. The solvents, water and an alkane, can be effectively removed at 90 °C or with 40 s of microwaving. The ink demonstrated excellent electrical conductivity of approximately 300 S/m, with good bending tolerance.The rate of ink formation was shown to be affected by the alkanes used, with the C16 based ink forming faster than the C7 based ink. A statistical approach for analyzing the correlation of the ink’s resistance with the number of prints and the width of the printed line was introduced, providing information about how the uniformity of the ink related to its mechanism of formation. The rheological properties of the ink indicated a wide range of suitable printing speeds, similar to typical commercially available screen-printing inks. This graphene stabilized emulsion ink demonstrates significant potential for enabling the next generation of paper based diagnostics to improve the medical and environmental diagnostics of underserved populations.2O followed by a forty-second bubble tea shaker shaking . The bubble tea shaker mimicked the process of hand shaking but allowed a more reproducible study of the effect of shaking time. An image of the bubble tea shaker can be found in Figure heptane (C7) and hexadecane (C16) ink used for screen printing are made by using 0.1 g graphite , 3 ml of heptane  or hexadecane , and 7 ml of DI HSamples for optical image of C7 and C16 ink are made by diluting the ink using the corresponding continuous phase to separate spheres, which means C7 ink was diluted using C7 and C16 ink was diluted with C16. Images were taken using Leica M125.The stencil used for screen printing are made using Speedball Diazo Ultimate Screen Printing Kit followed by the instruction. Paper used for screen printing is Heavyweight Drawing from Strathmore. When preparing samples for the electrical conductivity study, each ink was printed on paper from 1 to 10 times using a stencil with designed lines widths from 1 to 6 pt. See Figure −1 was performed, and the testing temperature is controlled at 30 °C.C7 and C16 ink used for viscosity measurements are used as it is once a full emulsion was obtained. Commercial screen-printing ink is a fabric screen printing ink purchased from Speedball. Viscosity of the inks are measured using the rheometer  with a sandpaper  modified parallel plate . A steady shear test from 0.1 to 200 sC16 and C7 ink sample were made using the bubble tea shaker to obtain a full emulsion and poured into an DT-1202 Acoustic and Electroacoustic spectrometer sample cell . The emulsion sphere size and its distribution were measured, and the attenuation spectra is analyzed using Dispersion Technology software.Conductivity of the printed ink line was measured using a two-point probe multimeter (Fluke 25 multimeter), and each measurement was repeated at least three times and an average was taken. Resistance value was reported as a function of the product of the line width and the number of prints. Samples for the ink conductivity measurement were prepared by drop casting it onto a glass slide, and dried at 90 °C in an oven for a week. Sheet resistance of the ink was measured using a four-point probe (Signatone S-302), and the thickness of the ink dot was calculated using the volume of the ink drop casted, loading of the graphite, area of the droplet, and graphene density. Conductivity of the ink is calculated based on the sheet resistance the thickness of the dry ink droplet.Exfoliated graphene sheet sample was obtained by dropping the ink into a large excess of the water. Emulsion droplets break and forms a graphene skin since the oil phase is no longer the continuous phase. A TEM grid  was used to lift the graphene skin. The graphene sample was characterized using TEM (FEI Lab6 20–120 kV transmission electron microscope) at 80 kV.Supplementary file 1