Background: Although poorer cognitive performance has been found to be associated with anxiety, it remains unclear whether neurocognitive function affects biased cognitive processing toward emotional information. We investigated whether general cognitive function evaluated with a standard neuropsychological test predicts biased cognition, focusing on attentional bias toward threat.Methods: One hundred and five healthy young adults completed a dot-probe task measuring attentional bias and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) measuring general cognitive function, which consists of five domains: immediate memory, visuospatial/constructional, language, attention, and delayed memory. Stepwise multiple regression analysis was performed to examine the relationship between attentional bias and cognitive function.Results: The attentional domain was the best predictor of attentional bias toward threat . Within the attentional domain, digit symbol coding was negatively correlated with attentional bias .Conclusions: The present study provides the first evidence that general attentional ability, which was assessed with a standard neuropsychological test, affects attentional bias toward threatening information. Individual cognitive profiles might be important for the measurement and modification of cognitive biases. Cognitive theories suggest that cognitive processing biased toward affective significance confers an increased risk for the development and exacerbation of emotional disorders Beck, . Such biBiased attention toward threatening information is one of the most widely studied cognitive biases. Attentional bias refers to a tendency to quickly identify and easily dwell on emotional stimuli , chronic subdural hematoma (n = 1), cerebral palsy (n = 1), Wilson disease (n = 1), histories of subarachnoid hemorrhage (n = 1) and hydrocephalus (n = 1), and strabismus (n = 1). Thus, data from 105 participants were included in the analyses .Participants were 113 individuals recruited via advertisements in a local magazine and billboards at Kitasato University. The eligibility criteria were as follows: no Axis-I psychiatric disorders or substance abuse history, which were determined using the Mini-International Neuropsychiatric Interview . BDI-II is a 21-item, self-report questionnaire to assess depressive symptoms experienced during the past 2 weeks  was employed to assess multiple domains of cognitive function. The RBANS is a representative, clinician-administered neuropsychological test for adults aged between 20 and 89 years  Parts A and B Reitan, , 1955 weTo measure attentional bias, we used the dot-probe task (DPT), the most commonly used and innovative program for attentional bias modification . The significance threshold was set at 0.05 (two-tailed).r(99) = −0.27, p = 0.006; r(99) = 0.20, p = 0.049, respectively], indicating that lower performance in attention-related functions was associated with biased attention toward threatening information. Although attentional bias was not significantly correlated with trait anxiety in the current linear model, its relationship with depressive symptoms bordered on statistical significance (p = 0.050).Mean scores and standard deviations (SDs) of the RBANS, TMT, depressive symptoms, trait anxiety, and attentional bias are presented in Table F = 6.06, R2 = 0.20, adjusted R2 = 0.16, p < 0.001; Table p = 0.006).Next, stepwise multiple regression analysis revealed that the attentional domain of the RBANS was the best predictor of attentional bias toward threat , was negatively correlated with attentional bias toward threat .As a reference analysis to specify which component of the attentional domain in the RBANS was more relevant to attentional bias, partial correlation analysis showed that the digit symbol coding of the attentional domain, not digit span [p = 0.041) and delayed memory scores , compared to men. This is partly consistent with a previous study that found a similar gender difference in the RBANS .Additionally, we performed a confirmatory analysis to examine whether there are gender differences in the RBANS. The ANCOVA, in which age and years of education were controlled for, showed that women had higher immediate memory scores  .Some limitations should be noted when interpreting the results. First, we used the RBANS to measure neurocognitive function. More detailed assessment tools for assessing neurocognitive function are necessary. Second, the semantic fluency scores in the present study were lower than the scores in the original study (Randolph, In summary, we revealed that general attentional ability, assessed with a standard neuropsychological test, affects attentional bias toward threat. Compromised neurocognitive function in a specific domain might affect biased cognition toward an emotional stimulus therein. Consideration of individual differences in neurocognitive function might be important for the measurement and modification of cognitive bias.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.


With transmission-type graphene SA, the EDFL shortens its pulsewidth from 483 to 441 fs and broadens its spectral linewidth from 4.2 to 6.1 nm with enlarging the pumping current from 200 to 900 mA. In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm. The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.The  Thus, graphene could overcome the non-uniform distribution and self-aggregation problem happened on carbon nanotube. In addition, graphene exhibits lower threshold intensity for saturate absorption than that of carbon nanotubes to take over other saturable absorbers for the passively mode-locked EDFL89To get rid of the complicated synthesizing and transferring process, the hydrogen-free and low-temperature plasma enhanced chemical vapor deposition (PECVD) of graphene has emerged3 and the lifted graphene was transferred to a smooth Si wafer afterwards. The atomic-force microscopy (AFM) top-view image and cross-sectional profile of few-layer graphene on Si wafer shown in in-situ dissolution-and-reduction after the hydrogen-free and low-temperature PECVD growth is roughly estimated as 6 ~ 7 layers. To characterize the saturable absorption feature of the few-layer graphene, the nonlinear transmittance obtained under the pumping with high-peak-power fiber laser  is shown in T of 3.5%. The absorption saturates at a pumping power of more than 3.23 mW due to the Pauli blocking effect, where the photons could pass through the optically bleached graphene. The corresponding modulation depth of the few-layer graphene is about 28%, which is already comparable with those of about 30% as obtained from the seven-layer graphene synthesized under high-temperature and hydrogen-rich environmentIn order to measure the thickness and calculate the layer number of the few-layer graphene, the ultra-thin nickel catalyst film was etched by FeCl2/Si substrate is applied as the catalyst for the dissolution-and-reduction synthesis procedure. Several advantages of nickel which favor the in-situ graphene synthesis are addressed below. First, the carbon atoms can still dissolve into the ultra-thin nickel film at relatively low temperature (<500 °C), which facilitates the reduction of few-layer graphene from cooling the nickel matrix after carbon deposition−1 is induced by the structural defects in graphene, the G peak at 1580 cm−1 certifies the C-C sp2 network, and the unique 2D peak at 2760 cm−1 denotes the existence of single-layer graphene3 carbon bondsD/IG intensity ratio value of about 0.3. The better quality of graphene could be obtained by post annealing on the nickel substrate at 900 °C2D/IG intensity ratio of the graphene after dissolution-and-reduction from ultra-thin nickel film grown by low-temperature hydrogen-free PECVD is about 0.45, indicating that the graphene is not mono-layer (with I2D/IG > 1) and bi-layer (with I2D/IG = 1). For tri- or more-layer graphene synthesized on ultra-thin nickel catalyst film with hydrogen-free and low-temperature PECVD, the layer number should be further defined by measuring its transmittanceTo facilitate the hydrogen-free low-temperature PECVD growth of few-layer graphene, the ultra-thin nickel coated SiOAs pumping current ranged from 400 to 600 mA, the measured TBP is deviated from 0.315 to indicate the incomplete soliton mode-locking phenomenon. Almost the same temporal and spectral shapes are obtained with nearly transform-limited TBP at pumping current of larger than 700 mA.In more detail, the autocorrelation traces obtained at different pumping currents beyond the threshold of 100 mA are shown in In comparison, three major differences between the reflection- and transmission-type graphene based passively mode-locked EDFL systems are addressed, the cavity length (due to the aid of circulator), the doubled linear loss and the twice enlarged saturable absorbance (due to retro-reflection in graphene). As the light passes through the graphene layer and reflects by the gold coated end-face, the equivalent layer number increases twice such that the reflection-type graphene based mode-locker inevitably causes more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system was believed to generate stabilized soliton-like pulse easier than that of transmission-type system. That is because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged passing through the graphene twice under the retro-reflector design. Unfortunately, the mode-locking performance would be slightly degraded with the circulator induced insertion loss, which needs a detailed analysis for comparing both reflection- and transmission-type graphene mode-locked EDFLs.To perform the retro-reflection type mode-locker, the From the monitored autocorrelation traces shown in et al. have demonstrated a stable mode-locked EDFL with pulsewidth of 415 fs and pulse energy of 7.3 nJ by using a CVD-grown atomic layer grapheneet al. have also utilized the CVD-grown multilayer graphene to produce a stable mode-locked fiber laser with 432-fs pulsewidthGraphene with high crystalline quality can serve as an effective saturable absorber for ultrafast mode-locked lasers due to its excellent optical properties, including ultrafast carrier response time, low saturation intensity, high nonlinear modulation depth and less scattering loss81027209253234363739in-situ dissolution-and-reduction CVD synthesized few-layer graphene.With our approach, the desorbed carbon atoms from the Ni film can self-assemble the few-layer graphene with highly layer uniformity. The PECVD synthesis can lower down the growth temperature to a critical value of 550 °C such that the dissolution rate of the decomposed carbon atoms in the Ni film can be minimized. By precisely controlling the growth temperature near the phase transition temperature of Ni, the minimal layer number of graphene can be obtained due to the smallest quantity of carbon atoms desorbed from Ni film. Without hydrogen passivation, the few-layer graphene with suppressed defects can still be obtained under low-temperature growth. Although there is a small amount of defects existed in few-layer graphene to degrade its mode-locking force, the sub-picosecond ultrafast passively mode-locked EDFL pulse can still be generated with the saturable absorption in the in-situ dissolution-and-reduction synthesis is roughly estimated as 6 ~ 7 by AFM. The few-layer graphene obtained under low-temperature and non-hydrogen environment demonstrates a nonlinear transmittance increased from 87.5% to 91% with a ΔT of 3.5% and a corresponding modulation depth of 28%. At maximal pumping power, the transmission-type graphene mode-locked EDFL shows a central wavelength of 1572 ± 0.5 nm with a pulsewidth of 441 fs and a spectral linewidth of 6.1 nm. The EDFL with a cavity length of 7.43 m reveals the repetition frequency of 28.57 MHz. The soliton mode-locking is induced by observing the significant Kelly sidebands. In contrast, the reflection-type mode-locker can only generate the passively mode-locked EDFL with a broadened pulsewidth of 796 fs and a shrunk spectral linewidth of 3.3 nm. The layer number the reflection-type graphene based mode-locker is doubled such that the insertion loss becomes twice more than the transmission-type one. The repetition frequency concurrently decreases to 16.66 MHz as the cavity lengthens to 12.7 m. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.For the first time, a low-temperature and hydrogen-free PECVD synthesized graphene is used as a mode locker in transmission- and reflection-types for passively mode-locked EDFL systems. A dissolution-and-reduction synthesis facilitates to dissolve carbon atoms into the ultra-thin nickel film at relatively low temperature (~550 °C). Subsequently, the formation of few-layer graphene is observed from cooling the nickel matrix after carbon deposition. The measured layer number of few-layer graphene synthesized by In experiment, the few-layer graphene at 550 °C is performed with the mixed methane and argon at gas flow rate of 3 and 200 SCCM, respectively. The deposition on 50 nm of Ni substrate by PECVD with the plasma power of 100 W sustains for 100 s. At initial stage, the carbon atoms are gradually dissolved into Ni film at substrate temperature beyond threshold, where the formation of hexagonal carbon ring structure cannot be initiated in the interstices of Ni film. By lowering the substrate temperature, numerous carbon atoms desorb from Ni matrix to form the hexagonal carbon ring structure, and the layer number of graphene on the Ni film is dominated by the amount of desorbed carbon atomsThe advantage of low-temperature growth is to rigidly control the quantity of carbon atoms desorbed from Ni film so as to precisely determine the layer number of self-assembled graphene. Without the need of high-temperature procedure, the precipitation of the dissolved carbon atoms in the Ni film can be reduced. Under the temperature as low as 550 °C , only a small amount of carbon atoms can be dissolved into the Ni film, so as to prevent the precipitation of abundant carbon atoms after cooling21In previous work, the layer number of graphene can be controlled by detuning either the deposition time of argon-diluted methane fluence or the thickness of the evaporated Ni film. For example, when decreasing the deposition time of methane from 600 to 100 s, the graphene layer number can be reduced from 8 to 3 layers3, where the Fe3+ ion can etch the Ni film to make graphene floating upon solution9423 solution is diluted by injecting deionized (DI) water. Eventually, the graphene is attached onto the end-face of a SMF patchcord that is put into the solution of DI water. The transfer procedure is illustrated in After hydrogen-free and low-temperature PECVD growth, the synthesized graphene on Ni film is immersed in an aqueous solution of FeClThese fiber pigtails with few-layer graphene were placed in the passively mode-locked EDFL system, as illustrated in In contrast, the second system with a reflection-type few-layer graphene saturable absorber in the passively mode-locked EDFL system is demonstrated as shown in To perform the passive mode-locking at appropriate pumping condition, the intracavity gain of the EDFL was determined under bi-directional pumping regime. The relationship of the output power and the intracavity gain versus input power is shown in How to cite this article: Peng, K.-J. et al. Dissolution-and-reduction CVD synthesis of few-layer graphene on ultra-thin nickel film lifted off for mode-locking fiber lasers. Sci. Rep.5, 13689; doi: 10.1038/srep13689 (2015).


Moreover, we show that the top hBN layer used in the transfer process acts as an effective top encapsulation resulting in improved stability to ambient exposure. The transfer method is applicable to other CVD-grown 2D materials on copper foils, thereby facilitating the preparation of van der Waals heterostructures with controlled doping.We report a CVD hexagonal boron nitride (hBN-) assisted transfer method that enables a polymer-impurity free transfer process and subsequent top encapsulation of large-area CVD-grown graphene. We demonstrate that the CVD hBN layer that is utilized in this transfer technique acts as a buffer layer between the graphene film and supporting polymer layer. We show that the resulting graphene layers possess lower doping concentration, and improved carrier mobilities compared to graphene films produced by conventional transfer methods onto untreated SiO Owing to its unique mechanical42O3101122 V−1 s−1. Recent attention has been devoted to graphene encapsulation using hexagonal boron nitride (hBN) layers, a lattice-matched insulating 2D material with atomically smooth surfaces that has enabled near phonon-limited room temperature carrier mobilities of 140,000 cm2 V−1 s−1 to be realised in exfoliated hBN/graphene/hBN heterostructures17The robustness of graphene during fabrication processes and the long-term stability of graphene devices are additional key issues that must be resolved in order to make graphene commercially applicable. Improved stability is attainable by encapsulating graphene devices with a protection layer. A number of approaches have been reported employing a variety of encapsulation materials including metal oxides Al2O31011, TiO213,2/Si substrate by a scooping technique (AT-hBN/Gr/SiO2 sample), but the final result can be further improved by dry transfer and full encapsulation with hBN.2 surface passivation techniques such as SAMs or hBN buffer layers significantly improve the electrical properties of CVD graphene2021222 structures by charged surface states and impurity scattering24252628292 sample is compared to three samples prepared using the WT technique differing only in the substrate treatment, including untreated SiO2 (WT-Gr/SiO2), SAM-modified SiO2 (WT-Gr/SAM) and hBN covered SiO2 (WT-Gr/hBN). For the SAM modification, an octadecyltrichlorosilane (ODTS) layer was utilized due to its higher efficiency of screening the charge impurities present on SiO2 layer20The novel transfer method is compared to the conventional, and improved wet transfer (WT) techniques. It has been demonstrated that SiO2, and a topological mismatch of PMMA/hBN and Gr/Cu interfaces is likely to be present because the PMMA film conforms to the morphology of the underlying copper substrate of the first hBN layerOptical microscopy images of the transferred graphene films confirm that regardless of the target substrate, the WT method results in continuous films with low density of defective structures such as tears and cracks . We noteThe crystalline quality of the graphene films was analysed by Raman spectroscopy, as shown in 343536373839404138393839−1 is 50 times weaker than for the G peak of graphene under same measurement conditions2 sample) does not introduce significant defects and results in a defect density even lower than that detected for the WT-Gr/hBN sample.Consistent with optical microscopy, the obtained micro-Raman maps show uniform coverage of the graphene films transferred using both conventional WT and the presented AT methods . Raman s2 where graphene is in contact with the hBN film, a pronounced upshift of the Pos(2D) is observed, indicating increased strain. Sample AT-hBN/Gr/SiO2 exhibits an elongated distribution, providing further evidence of increased strain variation, as expected from the AT technique. In contrast, the conventional WT-Gr/SiO2 sample exhibits correlations between Pos(G) and Pos(2D) that are consistent with doping variations in the sample. This is attributed to the fact that the graphene film is in direct contact with SiO2, which introduces doping variation due to the presence of charged surface states and impurities2425202 substrate. However, since the CVD hBN layer was transferred using the conventional WT method, polymer residues present on the surface introduce additional doping variations in the WT-Gr/hBN sample. Notably, the AT-hBN/Gr/SiO2 sample demonstrates lower doping variations even though the graphene film is in direct contact with SiO2, which is consistent with the absence of surface polymer residues. The correlations between the Pos(G) and I(2D)/I(G) are shown in the 2D histograms of 2 sample makes the doping analysis difficult.The 2D histograms for Pos(G) and Pos(2D) are shown in D), defined as the conductivity minimum, provides direct information about the magnitude of the extrinsic doping and facilitates comparison between the different transfer techniques. Although carrier mobility is another important parameter for the material quality characterization, device length scale is important. In the current study, we have chosen to make the devices using a shadow mask technique. The advantage of this technique is that it avoids exposing the graphene to additional polymer residues for example during a photoresist or ebeam resist step, allowing us to isolate extrinsic doping induced by the transfer method alone. Additionally, shadow masking prevents graphene removal and delamination during lift off processThe material quality was further analysed by examining the electrical properties of graphene FET devices in terms of the charge neutrality point and carrier mobility (see Methods section for more details on the fabrication process). The charge neutrality point, or the Dirac point . For the sample WT-Gr/SAM, the VD is located at lower gate voltages compared to WT-Gr/SiO2 implying reduced p-type doping, consistent with the passivation of the SiO2 surface by the SAM. In contrast, the hBN buffer layer (WT-Gr/hBN) appears to have a negative effect, displaying a VD upshift compared to the WT-Gr/SiO2 sample, indicating an increased p-type doping, consistent with the presence of polymer residues on the underlying hBN surface. The lowest doping is observed for the hBN-assisted transfer (AT-hBN/Gr/SiO2) which exhibits a VD ~ 7 V, significantly downshifted compared to WT-Gr/SiO2. Since the graphene film is still in direct contact with the SiO2 substrate, this result can be attributed directly to the absence of polymer residues on the graphene surface. From analysis of the VD we deduce that the absence of polymer residues results in a 2.7 × 1012 cm−2 reduction in the doping level , ε0 is the permittivity of free space and dg is the thickness of SiO2 (90 nm). This method provides results comparable to those reported previously using a similar calculation of the graphene mobility from two-point FET measurements2031482 V−1 s−1 is obtained for the Gr-SiO2 sample, which is consistent with literature values31μh/μe ~ 3.2), which can be attributed to the presence of charge trap states on the SiO2 substrate2. This is perhaps surprising, since the SAM is expected to passivate reactive sites such as silanol groups at the SiO2 surface20μh/μe ~ 2.2 indicating that the ODTS layer screens the charged impurities from the adsorbates on the SiO2 surface. In the case of the WT-Gr/hBN sample, while the hole mobility remains quite high, the hole/electron mobility imbalance is much stronger with μh/μe ~ 9 providing further evidence of the presence of polymer dopants on the hBN surface. Finally, we find that for the AT-hBN/Gr/SiO2 sample the electron and hole mobilities are increased several-fold (even taking into account reproducibility across devices) compared to the standard WT-Gr/SiO2 sample. Noticeably, the asymmetry of the electron and hole mobilities remains high (μh/μe ~ 3.7) due to direct contact of the graphene film with the SiO2 substrate.where 2, WT-Gr/SAM and WT-Gr/hBN  followed by a thorough rinse in DI water. The floating PMMA/graphene or PMMA/hBN stack was scooped out using the target substrate. After drying, the sample was annealed at 180 °C for 30 mins. Finally, the PMMA was removed in acetone followed by IPA rinse. Three samples were prepared using the conventional wet transfer (WT) technique differing only in the substrate treatment, including untreated SiO2 (WT-Gr/SiO2), SAM-modified SiO2 (WT-Gr/SAM) and hBN covered SiO2 (WT-Gr/hBN). For the SAM modification, an octadecyltrichlorosilane (ODTS) layer was utilized due to its higher efficiency of screening the charge impurities present on SiO2 layer202-plasma activation of the SiO2 and spin casting from toluene solutionMonolayer graphene/Cu (25 μm) and hBN/Cu (25 μm) foils were purchased from Graphenea and Graphene Supermarket, respectively. Graphene/Cu or hBN/Cu layers were first covered with PMMA A4 495 by spin coating at 3500 rpm for 60 s and curing at room temperature overnight. Graphene or hBN present on the bottom side of the foils were removed using an O2 using the WT procedure (AT-hBN/Gr/SiO2 sample).The hBN/copper foil was coated with a relatively thick layer of PMMA (7% at 2500 rpm for 60 s). A frame of kapton tape was then applied to the PMMA/hBN/Cu stack to facilitate the dry transfer. After Cu etching and rinsing, the PMMA/hBN stack was removed from the DI water and dried at 60 °C for 1 hour. The sample was then ready for application directly to the target substrate, which in this case was the graphene/Cu foil. By these means a clean interface between hBN and graphene layer was created. After annealing at 180 °C for 30 mins, Cu etching and rinsing steps were repeated. The number and order of stacked 2D layers is in principle unlimited. To provide comparable results, in this work we limit ourselves to one hBN-Gr stack, which was applied to the SiO2-plasma treatment, while the second step provided the necessary pattern for contact deposition (Cr (5 nm)/Au (40 nm)). Graphene FET channel width and length were 100 and 1000um, respectively. The transfer characteristics of the graphene FETs were analyzed using a Keithley 2634B semiconductor parameter analyser unit under ambient environment with a two-point measurement for source and drain electrodes.The electrical properties of the transferred graphene films were examined in a field-effect transistor (FET) geometry. For the WT samples, top-contact Cr (5 nm)/Au (40 nm) electrodes were thermally evaporated through shadow masks directly onto graphene films to avoid further contact with polymers such as photoresist. For the hBN-assisted sample, photolithography can be used due to the protection provided by the top layer hBN. In this case, the edge-contacts were fabricated using a two-step photolithography process−1 and lateral resolution of 0.3 μm. Areas of 15 × 15 μm were mapped out and analysed to provide a sufficient statistical description of the overall graphene quality, since strong spatial variations in the Raman spectra are usually observed over the transferred graphene filmRaman spectroscopy measurements were performed using a confocal scanning Raman microscope (WiTec Alpha300 system) in backscattering geometry with 532 nm excitation and a 100 × objective (0.9 NA). An incident laser power of 1 mW was used to avoid laser induced heating of graphene samples. Measurements were performed at room temperature under ambient conditions, with an accumulation time of 0.5 s, a spectral resolution of 3 cmThe data that support the findings of this study are available from the corresponding authors on request .How to cite this article: Shautsova, V. et al. Hexagonal Boron Nitride assisted transfer and encapsulation of large area CVD graphene. Sci. Rep.6, 30210; doi: 10.1038/srep30210 (2016).


The unique properties of graphene, such as the high elasticity, mechanical strength, thermal conductivity, very high electrical conductivity and transparency, make them it an interesting material for stretchable electronic applications. In the work presented herein, the authors used graphene and carbon nanotubes to introduce chemical sensing properties into textile materials by means of a screen printing method. Carbon nanotubes and graphene pellets were dispersed in water and used as a printing paste in the screen printing process. Three printing paste compositions were prepared—0%, 1% and 3% graphene pellet content with a constant 3% carbon nanotube mass content. Commercially available materials were used in this process. As a substrate, a twill woven cotton fabric was utilized. It has been found that the addition of graphene to printing paste that contains carbon nanotubes significantly enhances the electrical conductivity and sensing properties of the final product. A key a2 hybridization, combined in hexagonal units. Due to the sp2 hybridization and specific electron configuration, graphene possesses unique properties, such as high mechanical strength (200 times higher than steel), high elasticity, very good electrical and thermal conductivity, and high permeability to light, making it transparent to visible light [Graphene is composed of a two dimensional carbon layer with sple light –6.These properties make graphene an extremely interesting option for applications in modern electronics, including printed electronics. One possible future application, due to its elasticity and durability, is in transparent electrodes and conductive layers, an especially vital application in the case of durable screens, touch panels and OLED screens ,8. GraphThe most adequate form for such applications is the graphene nanopellet (GNP), obtained by physical methods, such as mechanical fragmentation of high quality graphite . In the Graphene-based sensing systems can be obtained by printing techniques. Printing pastes are prepared by introducing GNPs to a formerly prepared polymer mixture  or by inIn the presented work, the authors have prepared printing pastes by doping multiwall carbon nanotubes (MWCNTs) with graphene pellets. The electrical properties of carbon nanotubes are exploited by many research teams, for instance, in inks produced for printing on foil and paper by means of specific printing methods –19.The authors have focused on the production of a dispersion paste based on commercially available graphene and carbon nanotubes. The physicochemical properties of the obtained materials were similar to those of typical printing pastes for commercial application as electronic printed elements on textile substrates . A screePrinting pastes were based on carbon nanotubes because they are a well-known material for printing conductive paths or textronic sensors . It was Additionally, the authors proposed a method for the preparation of the printing pastes, obtained by adding cross-linking ingredients to the aqueous dispersion for stronger bonding of the nanoadditives with the textile substrates. The authors chose to apply cross-linking ingredients due to the lack of information concerning the toxicological effects of nanomaterials deposited on textile substrates. Aliphatic urethane acrylate Ebecryl 2002  and a photoinitiator  were used to ensure a durable connection between the paste and substrate.2.2.1.® 7000 series, 90% purity, with nanotube dimensions of 9.5 nm in average diameter and 1.5 μm in average length. Aquacyl AQ0301 is characterized by a surface tension of approximately 58 mN/m, 43 P viscosity and pH = 7, measured by a surface tension analyzer Thermo DCA Radian 315 , rheometer DV3T LV  and pH-meter Elmetron CPC 505 , respectively. The above parameters were determined at 25 °C.An aqueous dispersion of carbon nanotubes, AquaCyl AQ0301 by Nanocyl , was used. It contained c.a. 3.0% MWCNT of the NanocylCommercially available graphene pellets were in the form of a dry powder and were purchased from the Graphene Supermarket . MO-1 graphene pellets were in the form of 5–30 nm multilayer pellets. This is one is the cheapest, but at the same time highest quality, graphene powders commercially available, obtained by fragmentation of kish graphite. This product is applicable for use in chemical and biological sensors as well as for other applications.2.2.P = 50 kV and a current of IA = 40 mA  was used. Scattering patterns over a 2θ angle range from 0° to 5° were acquired using a CCD camera.The shape and dimensions of the nanomaterials were investigated by X-ray diffraction, allowing for the collection of average values from a large sample series. Investigation of the carbon nanotubes was conducted by means of small angle X-ray scattering (SAXS). SAXSess equipment equipped with a CuKα source emitting X-rays of wavelength λ = 0.154 nm under a voltage of UP = 40 kV and a current of IA = 30 mA. Diffraction patterns covering a 2θ angle range from 0° to 60° were acquired using an X'Celerator counter.The thickness of and d-spacing between graphene layers of the pellets were determined by wide angle X-ray diffraction (WAXS). An X'PERT PRO from PANanalytical  was used, equipped with a CuKα source emitting X-rays of wavelength λ = 0.154 nm under a voltage of U2.3.For the preparation of the printing pastes, graphene pellets (MO-1) were introduced at 1 and 3%wt. to an aqueous dispersion of carbon nanotubes (AquaCyl AQ0301).The composite paste was placed in an ultrasonic tank SONIC 3  for 15 min, and then, aliphatic urethane acrylate, Ebecryl 2002, were added along with the Esacure DP250 photoinitiator, after which the system was mixed for 0.5 h using a mechanical stirrer RZR1 .The resulting pastes' surface tension, viscosity and pH were characterized. The results were approximately 65 mN/m, 95 P and pH 7 (at 25 °C), respectively, measured by a surface tension analyzer (Thermo DCA Radian 315), rheometer (Brookfield DV3T LV) and pH-meter (Elmetron CPC 505). No changes in the rheological parameters were observed after adding graphene pellets to the printing paste.3 and a thickness of 0.410 mm, measured according to the standards EN 29073-1:1992 and EN 29073-2:1992. The apparent density, 503.17 kg/m3, was calculated as a ratio of the measured mass per unit area to the fabrics thickness.Prepared pastes were applied on a cotton fabric with a twill weave, characterized by a surface mass of 206.3 g/m2. The obtained prints were fixed using the cross-linking process by exposing the sample to an IR emitter, type 1384 IR1 250 W Lamp  for 30 min.The printing process was realized by means of a screen printing machine with an automatic squeegee, MS-300FRO . Sheets of A4 were printed using a screen with a 49 mesh/cm2.4.s) was calculated by the The electrical properties of the printed woven fabrics were measured according to the standard EN 1149-1:2008 Protective clothing-Electrostatic properties Part 1: Surface resistivity (Test method and requirements). Sample conditioning (24 h) and measurements were performed under isothermal conditions (T = 23 °C) at a relative humidity value of 25% in a conditioning chamber. The electrical resistances of the studied samples were measured along the longitudinal direction (to determine the surface resistance) using a ring electrode , a Keithley 610 C electrometer  and a Statron stabilized power supply of unit type 4218 . According to European Standards, the surface resistivity (ρ2.5.Y is the liquid density (mg/m3), X is the ppm content, M is the molar mass, V is the chamber volume (m3), and cM is the mass of liquid evaporated. The value determined by To test vapor sensitivity, two solvents were selected (acetone and methanol according to standard EN 14605+A1:2010), and measurements were carried out with the use of a laboratory measurement system ,24. The 3.3.1.X-ray techniques are universal and allow for fast analysis of the target sample quality, shape and dimensions. The SAXS spectrum of the carbon nanotubes is shown in The obtained SAXS spectrum has a typical shape for cylindrical objects, having a diameter less than 100 nm, similar to MWCNT . This red is the d-spacing in the Z direction, λ is the X-ray wavelength, and θ is the X-ray diffraction angle of the given crystal.Graphene pellets were characterized by WAXS. In The next step was to determine the thickness of the graphene layer, according to the Scherrer The WAXS spectrum analysis allowed for characterization of the commercial graphene pellets. The average measured thickness is 23 nm (68 graphene layers), confirming specifications from the manufacturer (Graphene Supermarket). This is different from standard graphene, which is composed of up to 20 layers to preserve its unique properties. At the same time, the used graphene pellets are commercially available and relatively cheap, which is extremely important from the point of view of commercial applications. The d-spacing between two graphene layers in the GNP materials was estimated. The obtained value of 0.337 nm suggests that this is not a typical graphene (0.335 nm)  structur3.2.The commercially available AquaCyl modified by a cross-linking compound resulted in worse electrical properties than the graphene containing printed samples. At the same time, the increase in graphene content decreases the surface electrical resistivity. It is worth noting that the decrease in surface resistivity is a nonlinear function of GNP addition. The addition of 3% graphene affects the results in the form of a three-fold decrease in resistivity, while the addition of 1% only results in a 30% reduction in resistivity. The presented results confirm that the graphene pellets act as an active modifier of the printing paste based on MWCNT.Additionally, during the experiment, the amount of graphene was not observed to affect the homogeneity of the final product. The coefficient of variation for the surface resistivity is below 3%, and organoleptic tests indicate no significant differences between studied samples. The influence of the cross-linking compound used, such as aliphatic urethane acrylate and the photoinitiator, was also insignificant, matching results reported in previous work ,25.rel) was used to express the relative change of the screen printed textile's surface electrical conductivity after exposure to chemical stimuli according to relR is the relative resistance, 0R is the initial resistance, and R is the final resistance.Taking into consideration the results from Considering the above results, it can be concluded that a change in sensor properties (measured as relative resistance) is proportional to the vapor concentration. Moreover, the studied samples were significantly more sensitive to methanol than to acetone vapors, where the relative change in resistance was above 50% (15% for acetone), and for the samples with a graphene concentration of 3%, it was above 80%. The different intensities of the reaction to various solvent vapors could be correlated to the difference in the electrical dipole moments of the molecules. The dipole moment of methanol is equal to 1.61 D, lower than acetone—2.91 D. Based on the observed results, the obtained printed sensors are more sensitive to solvents with a lower electrical dipole moment, less than 3 D. Hence, it is possible to use screen printed textiles for determining the concentration of chemical vapors.In 4.The purpose of this article was to report on screen printing pastes for use on textiles substrates. The modification of printing pastes by the addition of carbon allotropes to give them interesting functional properties for specific applications was achieved. These modified pastes can be easily used for textile sensors in chemical manufacturing plants where the risk of vapor poisoning is high, as standalone sensors or as a part of protective clothing. The experimental results on sensor properties with respect to the detection of chemical stimuli proved that these fabricated sensors could be used periodically, after a particular relaxation time, differentiating them from disposable sensors. Possible future research should concentrate on creating a reliable data acquisition system, signal amplification system and analog to digital conversion system that would allow for integration with IT platforms to monitor any risks to humans in the work environment.


Theoretical and experimental studies confirmed that hydroxyl can be an effective sp3-type candidate for inducing robust magnetic moment. However, the artificial generation of hydroxyl groups for creating high-density spins on the basal plane of graphene sheet is very scarce. Here we demonstrate that high-content hydroxyl groups can be generated on the basal plane of graphene oxide (GO) sheet by ring opening of epoxy groups. We show that by introduction of 10.74 at.% hydroxyl groups, the density of localized spins of GO can be significantly increased from 0.4 to 5.17 μB/1000 C. Thus, this study provided an effective method to obtain graphene with high-density localized spins.Creation of high-density localized spins in the basal plane of graphene sheet by introduction of  Recently, sp3-type functionalization is widely recognized to be an effective route to generate magnetic moments on the basal-plane sites of graphene sheets891011121314sp3-type defects can be introduced on the basal plane of the graphene sheet, this kind of approach is considered as hitherto the most promising approach to induce high-density localized spinssp3-type approach has been experimentally realized by functionalizing graphene with H and F81617sp3-type approaches to create high-density localized spins on basal plane of graphene sheets.Magnetism of graphene is gaining increasing interest in recent years for its potential application in spintronics because its long spin-relaxation time provides the ideal condition to manipulate the spins12456sp3-type candidate for inducing localized spins on the basal plane of graphene sheet. Even the superiority of hydroxyl group in inducing localized spin, the artificial generation of hydroxyl groups for creating high-density spins on the basal plane of graphene sheet is very scarce.Graphene oxide (GO) is a typical graphene derivative. To micron-sized GO sheet, there are generally some basal-plane oxygen-containing groups (epoxy and hydroxyl groups) on its basal plane and small fraction of edge oxygen-containing groups (carbonyl and carboxyl groups) at edge sites1911141521224) as the alkaline reagent2728294. Our results clearly indicate that by generating high-content hydroxyl groups via ring opening of epoxy groups, the high-density localized spins can be created on the basal plane of OHG sheets. Moreover, we show that the magnetization of GO can be increased from 0.136 to 3.11 emu/g via ring opening of epoxy groups combined Ar annealing method.In general, micro-sized GO sheet obtained by chemical exfoliation of graphite powder has high-content epoxy groups, which is much more than that hydroxyl groups20222324254 solution, a large amount of hydroxyl groups can be generated on the basal plane of GO sheets. Shown in 4, similar to the result reported1 (284.5 eV), I2 (285.8 ± 0.2 eV) and I3 (286.5 ± 0.2 eV) respectively correspond to sp2 carbon atoms with their first nearest neighbors being also graphitic sp2 C atoms, hydroxyl group and epoxy group22262223253233224 reduction, the content of epoxy groups decreased to only 8.08 at.% synchronized with the significant increase in the content of hydroxyl groups  as a function of field H of GO and OHG. The M-H curves of both GO and OHG are well fitted using the Brillouin functionWe then performed the magnetic measurements of GO and OHG. Ms = NgJμB, x = gJμB/kBT, g is the g-factor (assuming g = 2), J is the angular momentum number, N is the number of spins and kB is the Boltzmann constant. Ms at 2 K can be obtained by fitting the corresponding M-H curves. It is found that Ms of GO is low (0.136 emu/g). By contrast, the value of OHG is as high as 1.71 emu/g, 13.6 times higher than that of GO. Subsequently, the spin density of GO and OHG can be extracted from the corresponding Ms, which was summarized in μB/1000 C, 12.9 times higher than the value of GO (0.4 μB/1000 C). It is clear that the spin density of GO has been significantly increased after introduction of high-content hydroxyl groups via ring opening of epoxy groups. In additional, different from GO which shows the fitted J value of 0.9, OHG shows the high fitted J value of 1.8. It suggests the formation of the larger spin clusters in OHG, similar to the theoretical results on large spin clusters generated by hydroxyl clusters11J value in OHG implies that the spin clusters grew after introduction of high-content hydroxyl groups via ring opening of epoxy groups. χ-T curve and corresponding 1/χ–T curve (inset in χ(T) curve to the Curie law χ = NJ(J + 1)g2μB2/3kBT. In other words, the creation of hydroxyl groups results in the enhancement of the paramagnetism of GO.where saturation magnetization inset in  of OHG. 4 on the ring opening of epoxy groups and magnetic properties, two extra OHG samples (OHG-50 and OHG-90) were prepared by changing the dosage of NaBH4 (50 and 90 mM). As illustrated in 4 dosage, the content of hydroxyl groups increases. It shows that the content of hydroxyl groups in GO can be tuned in a relatively wide range by adjusting the usage of NaBH4. Ms measured at 2 K  by annealing of GO at an appropriate temperature ranged from 300 to 500 °C, some of the epoxy groups can be removed and extra hydroxyl groups can be generated, and (ii) the Ms . The 3d impurity elements of all the samples were measured by inductively coupled plasma spectrometry , and are negligible . XPS measurements were performed on PHI-5000 VersaProbe using Al Ka radiation. The magnetic properties of the samples were measured by SQUID magnetometer with sensitivity less than 10How to cite this article: Chen, J. et al. Creation of localized spins in graphene by ring-opening of epoxy derived hydroxyl. Sci. Rep.6, 26862; doi: 10.1038/srep26862 (2016).


In this work, we explore the existence of spoof surface plasmons (SSPs) supported by deep-subwavelength high-contrast gratings (HCGs) on a perfect electric conductor plane. The dispersion relation of the HCGs-based SSPs is derived analyt- ically by combining multimode network theory with rigorous mode matching method, which has nearly the same form with and can be degenerated into that of the SSPs arising from deep-subwavelength metallic gratings (MGs). Numerical simula- tions validate the analytical dispersion relation and an effective medium approximation is also presented to obtain the same analytical dispersion formula. This work sets up a unified theoretical framework for SSPs and opens up new vistas in surface plasmon optics. Surface plasmons (SPs) are the area of intense interest at optical frequencies12457810121314151617et al.192122Q optical resonators and ultralow loss hollow-core waveguides251819However, the characteristics of field confinement on the surface of metals and the intrinsic ohmic losses of most real metals will lead to a non-negligible propagation loss of the SSPs in long range transmissions, especially at upper end of microwave frequencies and THz frequencies. Moreover, as mentioned by Park In this work, we extend the concept of SSPs by demonstrating that HCGs on a PEC plane shown in 272930A and B with widths dA and dB, relative permittivities In x direction and the perpendicular wave vectors z direction with x direction satisfy the Floquent condition x direction, the fields in Region I also contain an infinite set of space harmonics with the longitudinal wave vectors We first assume that a TM-polarized plane wave with free space wavenumber To obtain the dispersion relation of this composite structure, we need to first solve a classical eigenmode problem when the HCGs region in the composite structure is regarded as an unbounded periodical array without the PEC and the air. Consequently, the fields in the unbounded HCGs can be expressed as a superposition of the obtained characteristic Floquet functions. Then, combining the multimode network theory with the Floquet condition, the dispersion relation of eigenmodes in the unbounded HCGs can be obtained272829in which z = 0, the input admittance matrix Ydn looking down into Region II can be obtained asSince the eigenmodes in the unbounded HCGs have been determined, the transfer relationship of admittance matrix for each region can be obtained by applying the standard matching boundary conditions that the tangential components of the EM fields are continuous at the interface between adjacent regions. Then at the interface Γ = −1 is the reflection coefficient matrix of the PEC plane and 1 stands for the unit matrix of infinite dimension. n-th space harmonic through the Fourier expansion of the m-th mode current and voltage of the transmission lines respectively, which can be obtained by solving the eigenvalue problem of an unbounded HCGs.in which z = 0, which is a diagonal matrixMeanwhile, it is easy to determine the input admittance matrix z = 0 interfacein which m = 0) of equation n = 0). For the case The determinant equation d as see h = d, εA = 20, μA = 1, εB = μB = 1. For comparison, the simulated dispersion curve is obtained by the commercial software COMSOL Multiphysics, which is in excellent agreement with the analytical one and shown as the blue dotted line in By combining equations xz plane when In order to gain a deeper insight into the behavior of the HCGs-based SSPs, we plot the distributions of the electric field h on top of the PEC surface )  denotes the imaginary part of ω) of the fundamental HCGs-based SSP and normal DSP modes are calculated and shown in δA = 0.001 and tanδA = 0.0002 respectively. As expected, owing to the low loss of the HCGs, the HCGs-based SSPs has a larger propagation length (287λ and 180λ for tanδA = 0.0002 and tanδA = 0.001 respectively when λ = 7.5d with d = 5 mm) compared with the normal DSPs (165λ for λ = 7.5d with d = 5 mm), see the intersection points of three curves with the vertical gray dotted line in Finally, we address the issue whether SSPs also arise in 3D composite structure. Here we demonstrate that domino-like HCGs on a metal plate can also support the propagation of HCGs-based SSPs. A sketch of the proposed model is shown in the inset of t = d but different values of d, ranging from 5 mm  to 0.05 μm . To calculate these bands, the actual dielectric function of copper is also employed in the simulations. If the real part of the dielectric permittivity keeps unchanged, the normalized dispersion relations are not sensitive to the frequency regime of operation, which shows that HCGs-based SSPs exist at microwave, terahertz, mid-infrared and even ultraviolet frequencies. Although the permittivity of one dielectric could not keep constant in the whole spectrum, it is anticipated that we could find a certain dielectric in a certain frequency range with a similar permittivity thanks to the progress of advanced materials.An important question concerning the frequency regimes the HCGs-based SSPs can operate in is depicted in In conclusion, we have demonstrated the existence of SSPs supported by deep-subwavelength HCGs on a PEC plane both in 2D and 3D cases. Excellent agreement between the analytical and numerical dispersions of the HCGs-based SSPs validate our theory. The dispersion relation has further been verified through an effective medium approximation. The HCGs-based SSPs supported by this system have close resemblances with the MGs-based SSPs both in dispersion relation and field distributions. Thanks to this new concept, a whole bunch of phenomena already known to work for MGs-based SSPs can be safely transferred to HCGs-based SSPs. This finding may have a significant impact on both fundamental and applied research in surface plasmon optics.m = 0) considered and all high-order diffraction effects ignored. Equation h and effective electric permittivity The analytical dispersion relation of the HCGs-based SSPs in equation 3 and CaTiO333All the numerical dispersion curves, electric fields and the corresponding electric-force lines distributions are performed with the help of the Finite Element Method (FEM) using the commercial software COMSOL Multiphysics, in which the corresponding eigenvalue problem is posed in a single unit cell with Bloch boundary conditions used. For the simulation of ideal metals, PEC boundary conditions are employed. For realistic metals, the dielectric function of copper is used10How to cite this article: Li, Z. et al. High-Contrast Gratings based Spoof Surface Plasmons. Sci. Rep.6, 21199; doi: 10.1038/srep21199 (2016).


More recently, we have shown by an siRNA knockdown method that the Ca2+-sensing receptor (CaSR) is upregulated in PASMCs from IPAH patients, involved in the enhanced Ca2+ response and subsequent excessive cell proliferation. In this study, we examined whether pharmacological blockade of CaSR attenuated the excessive proliferation of PASMCs from IPAH patients by MTT assay. The proliferation rate of PASMCs from IPAH patients was much higher (~1.5-fold) than that of PASMCs from normal subjects and patients with chronic thromboembolic pulmonary hypertension (CTEPH). Treatment with NPS2143, an antagonist of CaSR or calcilytic, clearly suppressed the cell proliferation in a concentration-dependent manner (IC50 = 2.64 μM) in IPAH-PASMCs, but not in normal and CTEPH PASMCs. Another calcilytic, Calhex 231, which is structurally unrelated to NPS2143, also concentration-dependently inhibited the excessive proliferation of IPAH-PASMCs (IC50 = 1.89 μM). In contrast, R568, an activator of CaSR or calcimimetic, significantly facilitated the proliferation of IPAH-PASMCs (EC50 = 0.33 μM). Similar results were obtained by BrdU incorporation assay. These results reveal that the excessive PASMC proliferation was modulated by pharmacological tools of CaSR, showing us that calcilytics are useful for a novel therapeutic approach for pulmonary arterial hypertension.Idiopathic pulmonary arterial hypertension (IPAH) is a rare and progressive disease of unknown pathogenesis. Vascular remodeling due to excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a critical pathogenic event that leads to early morbidity and mortality. The excessive cell proliferation is closely linked to the augmented Ca Pulmonary arterial hypertension (PAH) is caused by functional and structural changes in the pulmonary vasculature. Pulmonary vascular remodeling is triggered by a progressive elevation of pulmonary vascular resistance and pulmonary arterial pressure in patients with PAH. The elevated pulmonary arterial pressure induces extensive changes in heart structure followed by right heart failure, and eventually death. PAH is clinically defined by chronic increases of pulmonary arterial pressure due to various causes and resting mean pulmonary arterial pressure of ≥25 mmHg , 2. The 2+ mobilization and signaling in PASMCs. A major trigger for the PASMC proliferation is elevated cytosolic Ca2+ concentration ([Ca2+]cyt). In PASMCs, [Ca2+]cyt is regulated by the balance of Ca2+ influx through Ca2+-permeable channels in the plasma membrane and Ca2+ release from the intracellular store sites. PASMCs express several Ca2+-permeable channels including voltage-dependent Ca2+ channels, receptor-operated Ca2+ channels, and store-operated Ca2+ channels cyt increase in IPAH-PASMCs, contributing to enhanced Ca2+ signaling and excessive cell proliferation in IPAH-PASMCs amino-2-hydroxypropoxy]benzonitrile) , Calhex 231 -2-[[(1R)-1-ethyl]amino]cyclohexyl]benzamide) (Sigma-Aldrich), and R568 (2-chloro-N-[(1R)-1-(3-methoxyphenyl)ethyl]benzenepropanamine) (Tocris Bioscience) are shown in d/[drug])n) (for inhibition) and Amax/{1+(Kd/[drug])n)+100 (for activation), where Kd is the apparent dissociation constant of drug , [drug] is the concentration of drug, n is the Hill coefficient, C is the component resistant to drug, and Amax is the maximum value of the response.Pooled data are shown as the mean±S.E. The statistical significance of differences between two groups was determined by Student’s t-test. The statistical significance of differences among groups was determined by Scheffé’s test after one-way analysis of variance (ANOVA). Significant differences are expressed in the figure as *p<0.05 or **p<0.01. The data of the relationship between drug concentrations and cell proliferation were fitted using the following equations: relative value (%) = 100-(100-C)/{1+. On the other hand, the proliferation of CTEPH-PASMCs was not influenced by the presence of NPS2143 , n = 5; 50 value of 1.89 μM and a Hill coefficient of 1.39 (n = 6). In CTEPH-PASMCs, there was no significant difference in cell proliferation in the presence of Calhex 213 . Similarly to normal PASMCs, the proliferation of CTEPH-PASMCs was slightly facilitated during the exposure to R568 for 48 h . The application of 3 μM Calhex 231 also inhibited the excessive cell proliferation in IPAH-PASMCs . The cell proliferation in IPAH-PASMCs was enhanced by 3 μM R568 . In contrast, the proliferation of normal and CTEPH PASMCs was not significantly changed by 3 μM NPS2143 , 3 μM Calhex 231 , or 3 μM R568 .To confirm our results obtained from the MTT assay, another quantitative colorimetric assay based on the BrdU incorporation method for cell proliferation was carried out in normal, IPAH, and CTEPH PASMCs. The excessive proliferation of IPAH-PASMCs was markedly reduced by the treatment with 3 μM NPS2143 for 72 h culture ; Our previous report showed that the excessive proliferation rate of IPAH-PASMCs was attenuated by siRNA knockdown of CaSR ; however2+]cyt plays an important role in regulation of the proliferation and migration of PASMCs. An increase in [Ca2+]cyt in PASMCs is an important stimulus for PASMC proliferation and pulmonary vascular remodeling under physiological and pathological conditions [2+]cyt and augmented Ca2+ influx, as well as the enhanced cell proliferation in IPAH-PASMCs. Importantly, the intraperitoneal injection of the calcilytic NPS2143 prevented the development of pulmonary hypertension and right ventricular hypertrophy in monocrotaline-induced pulmonary hypertensive rats and hypoxia-induced pulmonary hypertensive mice. Functionally upregulated CaSR in PASMCs may be involved in a novel pathogenic mechanism underlying excessive pulmonary vascular remodeling in IPAH patients. In this study, we have direct evidence in vitro that calcilytics specifically inhibit the excessive proliferation of IPAH-PASMCs. Interestingly, calcilytics did not affect the cell growth of normal PASMCs. Pharmacological blockade of the upregulated CaSR with calcilytics may be a novel therapeutic approach for PAH patients who do not respond to conventional drug therapy. On the other hand, a calcimimetic enhanced the proliferation of IPAH-PASMCs. Even for normal and CTEPH PASMCs, cell growth was slightly but significantly increased by a calcimimetic. This result is in agreement with our previous observation that CaSR is expressed at low levels in the plasma membrane of normal PASMCs cyt and thereafter induces vasoconstriction under physiological conditions [2+]cyt increase mediated by CaSR activation triggers MAPK cascades to accelerate PASMC proliferation under physiological and pathological conditions. Therefore, the blockade of CaSR by calcilytics caused attenuation of excessive cell proliferation in IPAH-PASMCs. Related to the decrease in cell viability by the treatment with calcilytics, these cells apparently exhibited altered morphological features, leading to outcomes such as cell damage and death. Calcilytics may cause apoptosis and necrosis followed by morphological damage involving cell death. However, further experiments are necessary to elucidate the mechanism underlying cell proliferation and death via the CaSR pathway.CaSR belongs to the G-protein-coupled receptor subfamily C , 21, 28.nditions –31. Thernditions –34. Altenditions –38. It i2+ channels [50 and EC50 values of these modulators on the proliferation of IPAH-PASMCs were close to the effective concentration ranges of CaSR in recombinant HEK293 cells [In pharmacological research associated with CaSR, NPS2143, Calhex 231, and R568 are widely used as CaSR modulators , 40. A pchannels . On the channels  Fig 1A)2+ channe93 cells , 44, 45.2+ channel blockers , such as nifedipine and diltiazem [2) . Moreover, numerous potential candidates have either been submitted for approval or are in development. Despite recent major therapeutic advances, current treatments of PAH do not achieve a cure of life-threatening disease. In this study, we have demonstrated that the PASMC proliferation is modulated by the activity of CaSR, which is upregulated in IPAH patients, and that this is a novel pathogenic mechanism underlying the augmented PASMC proliferation in IPAH patients. These results also provide an important pathway for developing therapeutic interventions for PAH. Calcilytics are potential drug candidates for the treatment of osteoporosis and other bone metabolism diseases [On the basis of our understanding of the pathological mechanisms of PAH, drug therapy for PAH has progressed in recent years via the development of several specific drugs that offer an effective alternative to voltage-dependent Cailtiazem . Currentdiseases , 40. TheOur previous reports showed that a calcilytic inhibited the development of pulmonary hypertension in monocrotaline-induced pulmonary hypersensitive rats and hypoxia-induced pulmonary hypertensive mice , 26. In


We obtain the surface stress of a single layer and multilayers of graphene supported on silicone substrates by measuring the deformation of the graphene-covered substrates induced by the surface tension of liquid droplets together with the Neumann’s triangle concept. We find that the surface stress of the graphene-covered substrate is significant larger than that of the bare substrate, and it increases with increasing graphene layers, and finally reaches a constant value of about 120 mN/m on three and more layers of graphene. This work demonstrates that the apparent surface stress of graphene-substrate systems can be tuned by the substrate and the graphene layers. The surface stress and the tuning effect of the substrate on it may have applications in design and characterization of graphene-based ultra-sensitive sensors and other devices. Moreover, the method may also be used to measure the surface stress of other ultrathin films supported on soft substrates. Surface stress of solids, which connects the macroscopic properties of solids and the chemical bonding state at a surface or an interface124571214172319222526272829313245153437γs/E of several tens of microns, where γs is the surface stress and E is the Young’s modulus of the solid40Nevertheless, the effects of surface stresses are not notable in normal conditions, and therefore, direct experimental measurement of the value of surface stress of solids has remained a challenge for a long time. The reported surface stress of solids is mostly based on theoretical calculations21640et al.404344In this Article, we investigate the apparent surface stress of graphene supported on silicone substrates , by exteet al.When focusing on the profile of the contact line region in et al.ϕ that satisfies the biharmonic equation:The similar deformation profiles and cusp shapes caused by liquid droplets near the contact lines on the bare and graphene-covered substrates imply that the same rule governs the deformation. Because graphene is the stiffest material ever found46r and z represent the radial and vertical coordinates from the position of the contact line on the surface of the substrate, respectively. The stress and strain of the substrate can be found in ref. 49where u(r) is the displacement in the horizontal direction; q(r) is the interface stress between graphene and the substrate; gE, hg and vg are the Young’s modulus, the thickness, and the Poisson’s ratio of graphene, respectively. Using the continuity conditions of the displacements and stresses at the interface of graphene and the substrate, this problem can be solved analytically based on the Fourier transform procedure  in the vertical direction can be related to the vertical deformation v as34344We use the extracted surface stress in the model developed above to describe the deformation profile. Assuming This problem can be solved analytically . Figure The single layer graphene we used above is polycrystal at the millimeter scale and it contains grain boundaries. Using the same method, we measure the surface stress of a centimeter-sized single crystal of a single layer of grapheneNext, we study the surface stress of multilayer graphene supported on a substrate. Here multilayers are obtained by two methods. The first one is the widely used layer-by-layer transfer method, which can precisely control the layers of graphene and is referred to as “stacked” graphene in 51et al.et al.et al.γs ≈ γsl , the cusp profile is approximately symmetric, except its tip. Thus, the model of Style et al.et al.In this study, we extracted the surface stress using the method developed in ref. The surface stress reaches a constant value on three and more layers of graphene means that the surface stress is mainly contributed by the three atomic layers near the surface, which constitutes a direct experimental confirmation of the general theoretical result that the contribution to the surface stress is mainly from the surface atomic layer and two layers under itIn conclusion, by measuring the deformation of substrates induced by the surface tension of liquid droplets, we find that the graphene-covered soft substrates have similar deformation profiles to that of the bare substrate, while the deformation magnitude is significantly reduced. The theoretical model that includes the effect of surface stress can remove the singularity of the deformation and thus agrees with the experimental measurement. Based on the Neumann’s triangle concept, we extract the surface stress of bare and graphene-covered substrates. The apparent surface stress of one layer graphene supported on the silicone substrate (PDMS) is 58.4 ± 1.1 mN/m, measured with glycerol, and is 60.6 ± 3.1 mN/m obtained with liquid paraffin. This apparent surface stress increases with the number of the graphene layers, and eventually reaches a value of ∼120 mN/m on three and more layers of graphene. The results reveal that the contribution to the surface stress of multilayer graphene is mainly from the three layers in the vicinity of the surface. This work provides a basic parameter of supported multilayer graphene, which is the commonly used structure in graphene-based devices212223243132et al.Two kinds of soft silicone, i.e., polydimethylsiloxane  and CY52-276 (Dow Corning), were used in our experiments. The soft PDMS samples were prepared by spin-coating the oligomer with a base-curing ratio 75:1 on clean smooth glass slides for 1 min at different speeds . After curing at 75 °C for 6 hours, we obtained soft silicone substrates of different thicknesses . The estimated Young’s modulus of the gel is ~2 kPa53To obtain the topography of the substrates, we physically attached fluorescent nanobeads  to the substrates. Each 180 μm × 180 μm square field of view contained ~2000 fluorescent beads, which covered a total area fraction of no more than 0.002. For PDMS surfaces fabricated by spin coating, the root-mean-square roughness is always less than 2 nmThe graphene samples we used were from three sources: the commercially available polycrystal single layer graphene, chemical vapor deposition (CVD) multilayer graphene (two layers and 3~5 layers) on a copper foil , and single crystal single layer CVD graphene on copper that was provided by the research group of Dr Dong Wang of the Institute of Chemistry of the Chinese Academy of Sciences, who and his co-workers recently developed a facile atmospheric pressure CVD method to grow centimeter-sized single-crystal graphene on copper foil5657The multilayer graphene-covered silicone was prepared by two ways. Firstly, for as-grown multilayer graphene, the graphene-covered substrate was obtained by direct transfer of as-grown multilayer graphene onto the silicone substrate as mentioned above. Here, we chose two layer as-grown graphene and 3~5 layer as-grown graphene .


Changes in respiratory tract microbiota have been associated with diseases such as tuberculosis, a global public health problem that affects millions of people each year. This pilot study was carried out using sputum, oropharynx, and nasal respiratory tract samples collected from patients with pulmonary tuberculosis and healthy control individuals, in order to compare sample types and their usefulness in assessing changes in bacterial and fungal communities.Most V1-V2 16S rRNA gene sequences belonged to the phyla Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Fusobacteria, with differences in relative abundances and in specific taxa associated with each sample type. Most fungal ITS1 sequences were classified as Ascomycota and Basidiomycota, but abundances differed for the different samples. Bacterial and fungal community structures in oropharynx and sputum samples were similar to one another, as indicated by several beta diversity analyses, and both differed from nasal samples. The only difference between patient and control microbiota was found in oropharynx samples for both bacteria and fungi. Bacterial diversity was greater in sputum samples, while fungal diversity was greater in nasal samples.Respiratory tract microbial communities were similar in terms of the major phyla identified, yet they varied in terms of relative abundances and diversity indexes. Oropharynx communities varied with respect to health status and resembled those in sputum samples, which are collected from tuberculosis patients only due to the difficulty in obtaining sputum from healthy individuals, suggesting that oropharynx samples can be used to analyze community structure alterations associated with tuberculosis. Recent studies suggest that microbial communities inhabiting the human body can influence the host's health status and contribute to disease . The humMycobacterium tuberculosis (Mtb), is a major global public health problem that affects millions of people each year and ranks as the second leading cause of death from an infectious disease worldwide, with 8.6 million new cases and 1.3 million deaths in 2012 (25% of them were HIV-associated) [Mtb pathogen typically affects the lungs (pulmonary TB) but can affect other sites as well (extrapulmonary TB). Individuals with pulmonary TB can expel bacteria by talking, coughing, or sneezing, spreading the pathogen through airborne particles that are inhaled by others. The complex Mtb-human host interaction and the resulting infectious process indicate that TB disease development may be a multifactorial process [Tuberculosis (TB), a respiratory disease caused by  process . MicroorRecent studies of the respiratory tract microbiota using sputum samples and mixtures of saliva and pharyngeal secretions indicate changes and possible associations with pulmonary TB ,9. In thTo assess respiratory tract microbiota associated with TB patients and healthy controls, we collected nasal, oropharynx, and sputum samples from six TB patients and nasal and oropharynx samples from six healthy controls. The inclusion and exclusion criteria can be found in Additional file U test . A first comparison showed that sputum samples had the highest diversity, followed by oropharynx and the least diverse were nasal samples. Both nasal and oropharynx samples from healthy controls were more diverse than samples from TB patients, with a significant difference in the Shannon index for nasal samples (Table t test (pairwise comparisons) [p = 0.017) and Thermi (p = 0.020) were significantly different among sample types . Principal coordinate analyses (PCoA) and unweighted pair group method with arithmetic mean (UPGMA) analyses performed to compare communities indicated that oropharynx and sputum microbial communities clustered together, whereas nasal samples clustered separately, consistent with previous analyses of oropharynx and nasal communities [t test for significant differences of averages to see if communities from the same sample type were more similar to one another than to the other communities. The oropharynx sample communities were as similar to the sputum sample communities as they were to each other , and likewise, communities from sputum samples were also indistinguishable from oropharynx communities, indicating that they are closely related.The V1-V2 hypervariable region of the bacterial 16S rDNA was amplified with primers 27F (5′ AGAGTTTGATCCTGGCTCAG 3′) and 338R (5′ TGCTGCCTCCCGTAGGAGT 3′) . Approxiarisons) , ANOVA (arisons) , were usmunities ,20 . Fourteen taxa differed significantly between nasal and oropharynx samples when both patient and control groups were analyzed together, but only some of these showed differences within each group: one for patients versus three phyla for controls . Taken together, these observations indicate alterations in these communities and raise the possibility that such imbalances could affect, or result from, infection and/or colonization.Samples were also analyzed in order to see changes in respiratory tract bacterial communities associated to health status. The only difference between patient and control groups, using either nasal and oropharynx samples separately or both sample types  together, was found in oropharynx samples, where unclassified sequences belonging to the Streptococcaceae family were more abundant in TB patients . In TB patients, Candida and Aspergillus were the most frequent genera for both sputum and oropharyngeal samples, even though no significant differences were found when compared with healthy controls. In contrast to Bacteria, significant differences at the phylum level between oropharynx and nasal sample communities were seen only in patients with TB but not in controls  and ITS-2 (5′GCTGCGTTCTTCATCGATGC3′)  and cond sampled . Again, M. tuberculosis, a possibility that can be further examined by studying changes in particular taxa or in functionality via metagenomic sequencing using samples collected at various time points. More importantly, there was a resemblance between communities from sputum in TB patients and those present in the oropharynx, both of which were distinct from the nasal microbiota. This study therefore indicates that oropharynx samples can be valuable for probing respiratory tract microbiota and sets the groundwork for more extensive comparison and analysis of possible microbial community imbalances associated with a diseased state such as TB.Differences in community diversity indexes and in abundance of particular taxa, specifically in oropharynx communities, between TB patients and healthy controls suggest disturbance of respiratory tract microbial communities, despite the overall similarity in terms of the major phyla identified. These altered communities could either result from or influence infection and/or colonization by The research complied with the standards and recommendations for biomedical research involving human subjects adopted by the 18th World Medical Assembly, Helsinki, Finland, June 1964 and the 59th Meeting, Seoul, 2008. Ethical standards also complied with resolution N°008430 (1993) established by the Colombian Ministry of Health for work with humans. Informed written consent was obtained from all participants prior to enrollment with approval by the Ethics Committee of Corporación Corpogen (Bogotá), Corporación para Investigaciones Biológicas-CIB (Medellín) and with the approval of the Research Committee METROSALUD, ESE (Medellín).BMI: Body mass index; HIV: Human immunodeficiency virus; ITS1: Internal transcribed spacer region 1; Mtb: Mycobacterium tuberculosis; OTU: Operational taxonomic unit; PCoA: Principal coordinate analyses; QIIME: Quantitative Insights Into Microbial Ecology; TB: Tuberculosis; UPGMA: Unweighted pair group method with arithmetic mean.The authors declare that they have no competing interests.PDP, MMZ, JR, and LEB were involved in experimental design. LEB assembled the population and epidemiological data and performed the sampling. LEB and MLC were involved in the molecular procedures. LDS, JRB, and JMA developed workflows for the analysis of bacterial and fungal diversity. LEB, LDS, MLC, JMA, and MMZ analyzed the data. LEB, LDS, MLC, and MMZ wrote and edited the paper. All authors read and approved the final manuscript.Definition of groups and inclusion and exclusion criteria. Parameters used to select the individuals for the study.Click here for fileDemographic and clinical characteristics of the population. Metadata that describes the most important demographic and clinical features of the study individuals.Click here for file


Rapid progress in graphene engineering has called for a simple and effective method to determine the lattice orientation on graphene before tailoring graphene to the desired edge structures and shapes. In this work, a wavelet transform-based frequency identification method is developed to distinguish the lattice orientation of graphene. The lattice orientation is determined through the different distribution of the frequency power spectrum just from a single scan line. This method is proven both theoretically and experimentally to be useful and controllable. The results at the atomic scale show that the frequencies vary with the lattice orientation of graphene. Thus, an adjusted angle to the desired lattice orientation (zigzag or armchair) can easily be calculated based on the frequency obtained from the single scan line. Ultimately, these results will play a critical role in wafer-size graphene engineering and in the manufacturing of graphene-based nanodevices.The online version of this article (doi:10.1186/s11671-016-1553-z) contains supplementary material, which is available to authorized users. Graphene has been known as the replacement for silicon due to its unique electronic, physical, and mechanical properties as well as its wide range of applications , 2. Althhttp://www.electronicsweekly.com/Articles/2010/02/03/47937/100mm-graphene-wafer-grown.htm). Therefore, it becomes absolutely necessary to develop a simple, fast, flexible, and controllable method to determine the lattice orientation (zigzag and armchair) of wafer-size graphene on various substrates before manufacturing. Recently, Sasaki et al. reported friction anisotropy on graphene studied by molecular mechanics simulation. It revealed the possibility of identifying the lattice orientation on graphene theoretically [To date, several different graphene patterning methods such as Catalytic Cutting Technique –19, SPM-etically . Althougetically , 31, theIn this paper, a wavelet transform-based frequency ratio identifying method is developed to determine the lattice orientation of graphene theoretically and experimentally. The uniqueness of the proposed method lies in using one or two friction scanning lines that can quickly distinguish graphene lattice orientation. Both theoretical and experimental results at the atomic scale have shown that the frequency ratio vary with the lattice orientation on graphene, based on which the lattice orientation on graphene can easily be distinguished. The findings in this paper will play a critical role in wafer-size graphene engineering and in the development of graphene-based nanodevices.The friction measurements on graphene were performed with a Multimode AFM (now Bruker) in air under ambient conditions . AFM probes with rectangular cantilevers were used with scan size 5 nm across. Its radius, length, width, height, and thickness are 10, 450, 50, 10, and 2 μm, respectively. The normal spring constant is 0.2 N/m. The scan rate has to be more 10 Hz. The total number of lines per image, which defines the pixel resolution of the image, was kept constant at 256. All images, except otherwise indicated, were flattened with a first-order line-wise correction fit. Graphene  are calculated respectively. Figure δ of the two main peaks varying with lattice angles means δ can be used as a main factor to determine lattice orientations. These results will ultimately provide the platform for the development of graphene-based nanodevice.The relationship between the frequency and lattice orientation has been further investigated based on wavelet transform. The simulation and experimental spatial frequency power spectrums based on wavelet transform are depicted in Fig. V0 is the barrier potential constant, a = 0.246 nm is the lattice constant of graphene, and  denotes the position of the tip.To identify graphene lattice orientations, we propose a model based on the frequency ratio. The interaction potential of graphene used here is the same as the one of graphite :1\documeδ = ω_2/ω_1 (0° ≤ θ ≤ 30°) is defined, and then the lattice angles can be determined byTherefore, zigzag orientations (single peak) and armchair orientations (double peaks) are easily determined only by peak distributions of the frequency power spectrum from a single friction scan line. For the lattice angles between zigzags and armchairs, frequency ratio δ is symmetrical at 30° in a hexagonal periodicity as shown in Fig. θ) by anticlockwise, and scan a single line to calculate δ.Rotation  should be the real lattice angle.If this θ).Otherwise, the real lattice angle should be , and integral gain (I gain) have to be adjusted to obtain a good AFM image. Figure The lattice orientation determination of a monolayer graphene is demonstrated in Fig. The properties of graphene strongly rely on its edge structures. However, there is no rapid way to determine the lattice orientation on graphene. A simple and controllable method is developed to distinguish the lattice orientation of graphene appropriately. The method proposed in the manuscript only needs one or two scan lines to obtain the frequency ratio based on wavelet transform. Both theoretical and experimental results at the atomic scale have shown that the frequency ratios vary with the lattice orientations on graphene. In addition, an adjusted angle to the desired lattice orientation can be easily calculated based on the frequency ratio and the distribution obtained in this work, ultimately providing the platform for graphene engineering and graphene based nanodevices. In the future, the effects of the structural complexities of graphene on frequencies will be investigated, such as local strain, defects, and puckering. Recently, some studies –41 have


Here we show that silane, serving as a gaseous catalyst, is able to boost the graphene growth rate to ~1 μm min−1, thereby promoting graphene domains up to 20 μm in size to be synthesized via chemical vapour deposition (CVD) on hexagonal boron nitride (h-BN). Hall measurements show that the mobility of the sample reaches 20,000 cm2 V−1 s−1 at room temperature, which is among the best for CVD-grown graphene. Combining the advantages of both catalytic CVD and the ultra-flat dielectric substrate, gaseous catalyst-assisted CVD paves the way for synthesizing high-quality graphene for device applications while avoiding the transfer process.The direct growth of high-quality, large single-crystalline domains of graphene on a dielectric substrate is of vital importance for applications in electronics and optoelectronics. Traditionally, graphene domains grown on dielectrics are typically only ~1 μm with a growth rate of ~1 nm min The growth of high-quality graphene directly on to dielectric substrates is of key importance for future electronic and optoelectronic applications. Here, the authors use silane-catalysed chemical vapour deposition to fabricate large graphene sheets, up to 20 μm in size, on hexagonal boron nitride. As the first isolated atomically thin crystal34567891011121314151617(h-BN) are found to be good candidates for the substrate of graphene devicesh-BN is obviously the best one because of its insulation properties, chemical inertness and small lattice misfit. Growing graphene directly on ultra-flat h-BN can greatly preserve the pristine properties of graphene, and the mobility of the aligned graphene grown on h-BN via the CVD method reaches 20,000–30,000 cm2 V−1 s−1 at room temperature−1) and the generation of domain sizes that are mostly smaller than 1 μm. Although the fabrication of a graphene domain 11 μm in size has been achieved, it took 72 h to complete the fabricationRecently, molybdenum disulfide, tungsten disulfide and hexagonal boron nitride h-BN by almost two-order of magnitude higher than that in the absence of gaseous catalyst. The introduction of the gaseous catalyst also effectively improves the percentage of precisely aligned domains on h-BN. These results present a promising route towards very high-quality, transfer-free graphene on dielectric substrates for electronic applications.In this report, we demonstrate that silane and germane as gaseous catalysts can boost the growth rate of graphene on −1, which increases by an order of magnitude to 50 nm min−1 when germane is introduced. If silane is introduced, the growth rate further increases to 400 nm min−1 and, if the substrate is further heated to 1,350 °C, the growth rate reaches ~1,000 nm min−1, which is very close to that of graphene grown on a metal surface by CVD  calculations are performed on armchair graphene, with the results shown in catalyst , when a h-BN latticeet al. also did systematic investigations of the graphene/h-BN super-lattice with different angular rotationh-BNh-BN lattice. The ‘C’ domains exhibit the typical polycrystalline structure, with a detectable moiré pattern only on some sub-domains. h-BN shown in h-BN is very sensitive to the angular separation between the graphene and h-BN when the angular separation is less than 1° , where the integrity of the pattern gives information of graphene crystallinity and the alignment can be judged by the periodicity and the rotation of the moiré pattern with respect to the  1° ref. . Although-BN by the GCA-CVD method are very similar to those for aligned or misaligned graphene flakes on h-BN made by mechanical exfoliation−1, which is broader than that of graphene domains with a large misalignment angle. Moreover, a shoulder peak located at 1,565 cm−1 that is non-dispersive =±2,±6,±10…, where n=0, 1, 2… is the Landau level index. A further investigation to demonstrate the effects of the secondary Dirac point upon the magnetic field is still underway.In the plots of s in Rxx  and platRxx  mixture flow of 10 cm3 per min (s.c.c.m.), corresponding to 15 Pa, and annealed for 5 min, after which the Ar/H2 flow was turned off. The C2H2 flow and a mixture of silane/argon or germane/argon (5% mole ratio of silane or germane to argon) were introduced into the system for the graphene growth. The pressure was kept at 5 Pa during the growth, and the growth time was in the range of 5–40 min. After growth, both the C2H2 and gaseous catalyst flow were turned off and the system was cooled down to room temperature with the Ar/H2 mixture flowing. The samples of graphene on h-BN grown on a quartz surface were first transferred to a highly doped p-type silicon wafer with a 300-nm-thick SiO2 capping layer for electrical transport studies.Before graphene growth, k=0.05–0.5 N m−1. To obtain a high accuracy, scanners with a travel range less than 10 μm along the X and Y directions were used. Calibration for the atomic resolution was performed with newly cleaved highly ordered pyrolytic graphite (HOPG) before the measurements where, after calibration, the mean distance between the vicinal carbon atoms was measured to be 0.142 nm. The integral gain and set-point were adjusted to be as low as possible to obtain optimal images, and the scan rate was set to a value in the range of 10–60 Hz to reduce the noise from thermal drift. Several hours of pre-scanning were carried out to warm up the scanner and ensure high imaging stability. Error in this orientation measurement varies by data points and was typically ±2°, although it sometimes reached ±3°.As-grown samples were characterized by an AFM  in contact mode, and the atomic-resolution images were obtained by the AFM  under ambient conditions. The AFM images on different surfaces were recorded in contact mode using SNL-10 AFM tips from Bruker that possess a nominal tip radius of less than 10 nm, and whose cantilevers possess a force constant −1. The energy barrier of every advance step was explored by climbing nudged elastic band method. The vacuum layer inside the super-cell was kept as large as 14 Å to avoid interaction with the adjacent unit cell. The Brillion zone was sampled as 1 × 2 × 1 grid meshes for the 7 × 5 slab and 1 × 1 × 1 grid meshes for the larger 8 × 6 and 7 × 8 slabs using the Monkhorst-Pack scheme during the calculation.All of the calculations were performed within the framework of the DFT as implemented in the Vienna Ab-initio Simulation Package. The exchange-correlation potentials were treated by the gradient density approximation, and the interaction between valence electrons and ion cores was described by the projected augmented wave method. The energy cutoff for the plane wave functions was 400 eV and the force acting on each atom was less than 0.02 eV ÅRaman spectra were obtained with a WITec micro-Raman instrument possessing excitation laser lines of 488/532/633 nm. An objective lens of × 100 magnification and a 0.95 numerical aperture was used, producing a laser spot that was ~0.5 μm in diameter. The laser power was kept less than 1 mW on the sample surface to avoid laser-induced heating. The Raman images were acquired using a WITec Raman system with a 600 lines/mm grating and a piezo crystal-controlled scanning stage under a 488-nm laser excitation. The scanning step was about 200 nm.h-BN flake on the 300-nm-thick SiO2/Si substrates is about 20 nm, the effective capacitance, Cg, can be estimated as 10.5 nF cm−2. Both the electrical transport and magneto-transport measurements were carried out in a physical property measurement system  via the standard lock-in technique.The Hall bar structure of the graphene devices was defined by a standard electron beam lithographic technique. The metal contacts (60 nm Au/10 nm Ti) were deposited through electron beam evaporation, whereupon the devices were annealed in a hydrogen atmosphere at 250 °C for 3 h to remove resist residues and to reduce the contact resistance between the graphene and electrodes before the electrical measurements. Because the thickness of the M.J. and X.X. directed the research work. H.W., X.X. and S.T. conceived and designed the experiments. S.T. fabricated the graphene samples. S.T. and H.W. performed the AFM experiments. H.W., H.X. and X.L. fabricated the electronic devices. H.W., H.S.W. and Q.S. performed the transport measurements. F.D., X.Y.Z., X.C. and X.H.Z. performed the DFT calculations. C.C. and T.Y. performed the Raman measurements. H.W., X.X., S.T., F.D., C.C. and T.Y. analysed the experimental data and designed the figures. H.W., S.T., C.C., T.Y., F.D., F.H., X.X. and M.J. co-wrote the manuscript and all authors contributed to critical discussions of the manuscript.How to cite this article: Tang, S. et al. Silane-catalysed fast growth of large single-crystalline graphene on hexagonal boron nitride. Nat. Commun. 6:6499 doi: 10.1038/ncomms7499 (2015).Supplementary Figures 1-11, Supplementary Tables 1-3, Supplementary Notes 1-3, Supplementary Discussion and Supplementary References