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


Despite its fleeting existence, H2CO3 plays an important role in the global carbon cycle and in biological carbonate-containing systems. The short lifetime in water and presumed low concentration under all terrestrial conditions has stifled study of this fundamental species. Here, we have examined CO2/H2O mixtures under conditions of high pressure and high temperature to explore the potential for reaction to H2CO3 inside celestial bodies. We present a novel method to prepare solid H2CO3 by heating CO2/H2O mixtures at high pressure with a CO2 laser. Furthermore, we found that, contrary to present understanding, neutral H2CO3 is a significant component in aqueous CO2 solutions above 2.4 GPa and 110 °C as identified by IR-absorption and Raman spectroscopy. This is highly significant for speciation of deep C–O–H fluids with potential consequences for fluid-carbonate-bearing rock interactions. As conditions inside subduction zones on Earth appear to be most favorable for production of aqueous H2CO3, a role in subduction related phenomena is inferred.Carbonic acid (H Yet, the exact crystal structure of β-H2CO3 is still unknown. The FT-IR and Raman spectra of solid H2CO3 below 220 K at low pressure are now well established and several theoretical studies have reported on the structure and stability of H2CO3 with respect to decomposition to CO2 and H2O as well as on the relative stability of its isomers and on their vibrational characteristics78131412CO3 at elevated pressure has been predicted by ab initio molecular dynamic simulations2CO3 (aq) have been found up to 1.94 GPaCarbon dioxide CO, when diacid H2CO, but theon2 ref. ; and dir2O/CO2 mixtures experimentally at high pressure and temperatures in a diamond anvil cell (DAC), looking for evidence of increased stability of molecular H2CO3 in aqueous solution at elevated pressure. Within the Earth, at depths corresponding to pressures of up to 4.6 GPa , temperatures are heterogeneously distributed2O/CO2 mixtures were compressed to the desired pressure and then heated by irradiation with a CO2 laser. The laser was focused to irradiate only a fraction of the sample. In this way, the behavior of the system at high T can be investigated in the center of the heated area while phenomena of the transition down to room temperature can be investigated on the hot spot periphery. A solid product was synthesized during laser heating and the pressure-dependence of the vibrational modes of this product was investigated up to 9.1 GPa at ambient temperature. Additionally, the stability of the solid product with respect to pressure was investigated by compression to 25 GPa after synthesis at 4.3 GPa. In the second set of experiments, the sample was heated resistively to up to 280 °C after compression to the desired pressure. During resistive heating, the evolution of the system was monitored in situ by IR absorption spectroscopy. In both sets of heating experiments, the pressure range from 1.5 to 4.6 GPa was covered.In this work, we studied H2/H2O mixtures with a wide range of pressures  up to 1500 °C by CO2 laser heating. The measurement on a CO2/H2O (1:1.4) mixture at 3.5 GPa shall serve as an example of our results. When the directly illuminated sample area was heated above the melting temperature of the components, only a small part around this area remains liquid due to the steep thermal gradients encountered in laser-heating experiments in a DAC. During laser-heating to about 1500 °C, a dark substance formed around the directly heated area, which disappears again when the laser spot is moved above it. However, the dark substance remained at the trailing end of the scanning movement which enabled us to deposit it in the whole sample area. The directly heated region remained clear after the laser was switched off  and the O-H stretching mode of H2O-Ice VII (3000-3400 cm−1) are greatly reduced with the appearance of these new peaks. The only compounds in the CO2-H2O binary system known to form from a reaction of its endmembers are CO2 clathrate hydrates2 clathrate hydrate can be excluded as its Raman spectrum2O and CO2 and even the recently discovered high-pressure modification was shown to decompose above a pressure of 1 GPa2O/CO2 mixtures known to exist as a solid is H2CO3. Indeed, the sharp peak at 1073 cm−1 is coincident with the intense mixed mode of the symmetric stretching vibrations νs(C–O) and νs(C=O) of crystalline H2CO3 , respectivelyip(COH) and ν(C–O) vibration in crystalline H2CO3  vibration of CO2. Also, the IR absorption spectra of both the dark and the light sample region at room temperature  revealed, that the dark product could be observed at any investigated composition  is found at slightly lower wavenumbers, the skeletal bending mode, δip(COO), δoop(COH), νas(C–O)/νas(C=O), and δip(COH) are found at higher wavenumbers than the bands from the reference spectra while νas(C=O), and νas(C(OH)2) appear essentially at the same frequency. We are confident that the position of IR absorption bands in H2CO3 is not very sensitive to temperature as the published IR absorption bands of H2CO3 from Kohl et al.et al.−1 Raman mode is sensitive to sample temperature we first synthesized the dark product as described above from a CO2/H2O (1:1.8) mixture at 4.0 GPa and then turned on the laser again at lower power to heat the center of the directly illuminated the sample area to below 700 °C. A video taken during laser heating  displays a red shift, δoop(COH), and νas(C–O)/νas(C=O), and δip(COH) blue-shift while νas(C=O) and νas(C(OH)2) do not shift significantly. Extrapolating to the low pressure at which the reference spectra were recorded, all modes observed in our experiment shift towards the published spectral features of H2CO3  initially held at 4.3 GPa as described above. After laser heating, the pressure increased to 5.2 GPa, consistent with earlier observations. The sample was then compressed to 25 GPa while the intense Raman band at 1073 cm−1 was recorded  along the thermal gradient at the edge of the directly heated area. To investigate this, a 1:1 mixture of CO2 and H2O at 2.4 GPa was resistively heated to 280 °C with a rate of 5 °C/min and the spectral evolution was monitored in situ by IR absorption spectroscopy  and νas(CO2) mode of HCO3− , no evidence for formation of aqueous H2CO3 appears to be an integral component of CO2/H2O mixtures at and above pressures of 2.4 GPa at elevated temperature. This finding can be rationalized on the following grounds. The relative abundance of H2CO3 and its dissociation products HCO3− and CO32− in an aqueous solution of CO2 is largely determined by the dielectric constant (ε) and the autodissociation constant Kw of its host solvent H2O, and both are complex functions of pressure (p) and temperature (T)23p favors increased ionization, i.e. an increase in Kw of water. As a result of this, in the carbonate system with increasing p, more ionic species (HCO3− and CO32−) are created from neutral, dissolved CO2(aq) due to the larger abundance of H+. Isobaric heating of water affects Kw and thereby the extent of ion pairing of the dissolved members of the carbonate system3− and CO32− in absence of metal ions can only mean pairing with H+, the free acid H2CO3 will be produced. Indeed, it has been observed that both ionization constants of aqueous H2CO3 decrease upon heating252SO4 was observed to increase from 3.2 to almost neutral pH when heated to 400 °C at 0.4 GPa and similar associative behavior upon heating is observed in aqueous solutions of HCl and H3PO4  and H2CO3 which is produced by the novel high-pressure technique presented herein in the investigated pressure range are likely identical.It has been shown here that H−1 Raman mode in the liquid area around the directly heated part of the sample means that solid H2CO3 does not dissolve under the high-pressure conditions of our experiment during laser-heating, even in presence of liquid water. This seems to contradict the observation that solid H2CO3 (produced during laser heating) disappears as soon as liquid water is present (during whole-cell heating). From the latter observation combined with the absence of re-precipitation of solid H2CO3 during slow cooling after whole-cell heating it can be inferred that solid H2CO3 is not thermodynamically stable in our experiment in presence of liquid water even at elevated pressure (>2.4 GPa). The formation and metastability of solid H2CO3 during laser heating must therefore be the result of a non-equilibrium process. Based on the observation of apparent of H2CO3 molecules at elevated temperatures during whole-cell heating, we suggest the following model for this non-equilibrium process. The concentration of H2CO3 molecules increases with temperature in CO2/H2O fluids above 2.4 GPa. By laser heating, a convective motion is initiated in the cell which transports mass away from the heated area, following the steep thermal gradient at its edges. In pure H2O, a polar molecule like H2CO3 would be expected to be miscible at all ratios. However, when CO2 is added to aqueous solutions, the ability to dissolve polar/ionic species is decreased due to the lower dielectric constant (ε) relative to pure H2O at the same conditions2/H2O mixture show an immiscibility gap for high concentrations of CO2 and solute with decreasing temperature while the same solute would be entirely soluble in pure H2O under the same conditions2CO3 molecules is transported to the cooler edges of the heated area faster than thermodynamic equilibrium can be re-established, H2CO3 concentrations could be high enough to make solid H2CO3 a stable phase in the CO2/H2O/H2CO3 ternary system. When the laser beam is moved across the sample, solid H2CO3 that precipitated from the hot fluid at the cooler edges of the heated area is then stabilized by the rapidly solidified CO2/H2O/H2CO3 matrix at the trailing end of the heated spot before it can dissolve by reaction with liquid water at lower temperatures. The steep thermal gradients that are apparently needed to produce solid H2CO3 in a DAC together with the apparent need for stabilization in a solid matrix make it highly unlikely that solid H2CO3 occurs as an abundant solid inside the Earth. However, the necessity of steep thermal gradients for the synthesis of solid H2CO3 also emphasizes the large effect rising temperature has on the abundance of dissolved molecular H2CO3 in deep fluids.The observation of the 1073 cm2CO3 has never been considered significant in models of COH fluids inside the Earth2CO3 is a stable species in aqueous fluids above 2.4 GPa (~ 85 km depth), and at least up to 280 °C at 3.5 GPa, and its overall stability field in aqueous fluids is far from being mapped. Some constraints can be put on the formation of H2CO3 from our experimental results, though. As a classic Brønstedt acid, its stability will depend strongly on pH with high H+ concentrations promoting H2CO3 formation. Its stability will also depend on the redox-state of the environment and is probably limited to regions where CO2 is stable, too. Furthermore, our experiments indicate that fluids present at higher temperature will contain more H2CO3 than cooler fluids.Due to its instability at ambient pressure, H2CO3 will be the simultaneous availability of free CO2 and H2O. In subduction zones, which probably show the most favorable conditions for formation of H2CO3 on Earth in terms of pressure, and temperature312 and H2O, aqueous carbon bearing fluids are created by devolatilization of the subducting slab2 with the expected peak concentration above 750 °C2 concentration in the fluid is well above the minimum pressure of 2.4 GPa identified by us for the stability of aqueous H2CO3. Production of aqueous H2CO3 could therefore be connected to subduction related volcanism.A limiting factor on the provenance of H2CO3 produced, CO2 and H2O could be significantly deprived from hot fluids through H2CO3 formation which has consequences on the geochemistry of these fluids. An apparent “masking” of H2O and CO2 in fluids at pressure above 2.4 GPa can have an influence on numerous properties of deep fluids like activity of its constituents, electrical conductivity, viscosity and density2CO3 below 2.4 GPa would be equivalent to a sudden release of CO2 and H2O which should be accounted for in models of deep fluids in this pressure region. If H2CO3 formation happens at the expense of ionic species of the carbonate equilibrium, increased solubility of carbonate minerals can be expected as compared to models neglecting H2CO3 formation2CO3 molecules in aqueous fluids above 2.4 GPa should concentrate on a quantitative description of the global carbonate equilibrium as all the above mentioned effects will strongly depend on the equilibrium concentration of H2CO3 under the respective conditions. These results will also be relevant for the geochemical modeling of large, water-rich exoplanets.Depending on the amounts of H2 (purity > 99.99%) was loaded into IIa type diamond anvil cell (DAC) containing ultrapure H2O (>18 MΩ) with the aid of a gas loader at 500 bar. The CO2/H2O ratio was determined from the relative volumes occupied by the then solid CO2 and H2O, considering the molar volumes at the respective pressure. Typically we used a gasket made of Rhenium or Platinum. The 632.8 nm line of a He-Ne-laser was used to excite the Raman spectra. Infrared (IR) measurements were conducted using a Bruker IFS-66V FTIR spectrometer equipped with a KBr beam splitter and a globar mid-infrared source. The IR beam size was adjusted according to the measured area. Spectra of the dark and the light region were recorded by shading off the part to be excluded from the light source of the spectrometer. High temperatures were achieved either by irradiation with a CO2-laser or by means of whole-cell external heating. In external heating experiments, the temperature was determined with the help of a thermocouple glued directly on one of the diamond anvils. In laser-heated experiments, temperature was determined by the glow color in the center of the heated area. While temperature estimation from the color of glowing may produce a big uncertainty, our experiments showed that crystalline H2CO3 can be synthesized in a wide temperature range as apparent from no visible glowing to a white glowing sample area. This means, that this big uncertainty in temperature has no significant effect on the validity of the results of this study. A ruby chip was inserted in the sample and the pressure determined from the peak wavelength of the R1 ruby fluorescence band.COHow to cite this article: Wang, H. et al. Stable solid and aqueous H2CO3 from CO2 and H2O at high pressure and high temperature. Sci. Rep.6, 19902; doi: 10.1038/srep19902 (2016).


Spin polarization and stacking are interesting effects in complex molecular systems and are both presented in graphene-based materials. Their possible combination may provide a new perspective in understanding the intermolecular force. The nanoscale graphene structures with zigzag edges could possess spin-polarized ground states. However, the mechanical effect of spin polarization in stacking of graphene nanofragments is not clear. Here we demonstrate the displacement between two stacked rhombic graphene nanofragments induced by spin polarization, using first-principles density-functional methods. We found that, in stacking of two rhombic graphene nanofragments, a spin-polarized stacked conformation with zero total spin is energetically more favorable than the closed-shell stacking. The spin-polarized conformation gives a further horizontal interlayer displacement within 1 angstrom compared with the closed-shell structure. This result highlights that, besides the well-known phenomenologically interpreted van der Waals forces, a specific mechanism dependent on the monomeric spin polarization may lead to obvious mechanical effects in some intermolecular interactions. The interactions between magnetic objects and the earth through the Earth’s magnetic field brought about the birth of compass. Analogizing this macroscopic magnetic induction, we expect to find a similar induced behavior between two molecules with a separation beyond bonding distance. So far, the magnetism of carbon-based materials has been confirmed in experiments13789The inference can be appropriately demonstrated by stacking of graphene nanofragments. Stacking is acknowledged as a typical structural balance held by intermolecular force, which is sensitive to monomeric electronic structure such as the π-electron delocalization in graphene. Realizations about this phenomenon can be traced back to the studies of structures of graphite. The concept of AB stacking for bilayer graphene originated from the Bernal structure for graphite determined in 1924131517S = 0 spin-polarized ground state. Then, the stacking systems of freestanding bilayer graphene nanofragments were constructed.According to studies and discussions above, we chose the rhombic graphene nanofragment with hydrogen passivated edge atoms to be the stacking monomer in this work, which possesses four zigzag edges and an S = 0 spin-polarized conformation has the lowest total energy which is about 0.42 eV lower than that of the closed-shell one. Furthermore, a horizontal displacement about 0.82 Å is presented between two fragments of the spin-polarized structure, compared with the closed-shell stacking. Thus, the slippage in stacking of graphene nanofragments induced by spin polarization is clearly demonstrated. The displacement is clearly shown in After structural optimizations, both spin-polarized and closed-shell stacked conformations of bilayer graphene nanofragments were obtained. The ones most stable in two states respectively are shown in S = 0 spin-polarized ground state of the single rhombic graphene nanofragment is stable when the size increases. And it’s suggested that the mechanical effect induced by spin-polarization would occur when the size of the system increases in a small range. Meanwhile, twisted stacking didn’t give a lower total energy than the optimal slipped conformation in our calculations. Comparison of the total energy among different states of the single rhombic fragment in different sizes can be found in In addition, the Spin-polarized stacked conformations different from the AA and AB stacking have been reported in bilayer zigzag graphene nanoribbons17201922This work, as a typical demonstration, pointed out the bridge between spin polarizations of nanoscale graphene structures and their complex structural conformations in intermolecular interactions. Meanwhile, as an example of intermolecular behaviors response to the monomeric spin polarization, we anticipate this finding to offer an inspiration for further explorations and designs.Simulations were implemented by first-principles calculations in Gaussian 0925How to cite this article: Lei, Y. et al. Slippage in stacking of graphene nanofragments induced by spin polarization. Sci. Rep.5, 10985; doi: 10.1038/srep10985 (2015).


M = 2000), N-methyldiethanolamine, and formic acid. It was found that addition of approx. 2 wt.% of graphene causes the loss of volume resistivity by three orders of magnitude and percolation threshold is already set at approx. 1 wt.%. The frequency characteristic of a real part of permittivity ε′ and imaginary part of permittivity ε″ were measured for the tested films. On the base of Havriliak–Negami equation, parameters of relaxation functions in frequency domain were estimated for samples containing various contents of graphene. The influence of the cationomer phase structure on observed changes of dielectric losses coefficient tgδ in the full-measuring frequency spectrum was discussed.The research was planned to test electrical properties of polymer films made from polyurethane cationomers with 0–2 wt.% graphene admixture. The cationomers were synthetized in the reaction of 4,4′-methylenebis(phenyl isocyanate), polycaprolactone diol ( It was found that the presence of graphene results in increased thermal and mechanical strength of received polymer films and contributes to the increase in hydrophobicity of generally hydrophilic coatings prepared from waterborne polyurethane cationomers [In the part I of the paper  synthesiionomers . Meanwhi3O4 particles modified by oleic acid, which were dispersed in PPG glycol under ultrasonic bath. The addition of 0–3.5 wt.% of Fe3O4 caused the loss of the volume resistivity of obtained polymer foils from the value of 1.04 × 1014 to 5.96 × 104 Ω cm and surface resistivity from the value 1013 to 105 Ω cm−2 [ε′) from the value of approx. 8 to 50 and dielectric loss constant (ε″) from the value of 0.1 to 0.9 measured by the frequency of 0.01 Hz. The measurements conducted in conditions of slow increase of frequency up to 106 Hz in the case of these nanocomposites containing above 1.5 % GO showed nonlinear loss of constants values ε′ and ε″, while these constants in the case of PU without admixtures had values 5 and below 0.1 and changed with frequency insignificantly [So far, there have been many descriptions of modifications of polymer electric properties, for typical dielectrics after admixture introduction of metal nanoparticles like Au, Ag, polyaniline, carbon black, or specially prepared multi-walled carbon nanotubes (MWCNT) –4. Limitficantly , electroN-metyldiethanoloamine. In order to obtain nanocomposites, graphene was previously noncovalent functionalized in THF in the field of ultrasound. The reference films were prepared by covering poly(tetrafluoroethylene) (PTFE) or glass plates by the polyurethane cationomers water dispersions. Next, the films were placed in a vacuum drier, at 80 °C, for over 6 h, and the process of film formation was completed by exposure to ambient air during 10 days. In this way, polymer films containing respectively 0 (PU-0 sample), 0.1 (PU-0.1), 0.5 (PU-0.5), 1 (PU-1), 1.5 (PU-1.5), or 2 wt.% (PU-2) of the graphene were received [The research included the polymer films prepared from polyurethane cationomer produced from polyurethane cationomers with added graphene. Polyurethane cationomer as polymer matrix for 0–2 wt.% graphene was synthesized in the reaction of MDI, polycaprolactone diol, and IEC 93:1980 Methods of test for volume resistivity and surface resistivity of solid electrical insulating materials.ASTM D 257-99 Standard test methods for dc resistance or conductance of insulating materials.The measurements of volume resistivity were taken in accordance with the fopllowing standards:There was a measuring setup used based on three electrodes, presented in Fig. −4–5 × 103 Hz. The relaxation processes and the basic dielectric parameters were defined on the basis of frequency domain spectroscopy (FDS). The system DIRANA of OMICRON was used to conduct measurements. The software Origin v.8.0 and WinFit of Novocontrol was used to present and analyze the results of the measurements. The generic complex equation Havriliak–Negami (H-N) equation was applied to set basic relaxation functions’ parameters in frequency, which described the changes of dielectric permittivity in frequency function [kk = 1 for low-frequency component HN1 and k = 2 for high-frequency component HN2);is the total number of partial  and optical high-frequency permeability is the polarizability, the difference between static permittivity (low frequency)  and 2,2-bis(hydroxymethyl)propionic acid (DMPA) had the volume resistivity of 1011 Ω m [Tg1 = −49.7 °C) and hard segments (Tg2 = −23.9 °C), that give it good mechanical properties and considerable polarity with high surface energy of 45.3 × 10−3 J m−2. In the chain of anionomers analyzed in the paper [8 Ω m for the pure material to 3.4 × 105 Ω m. The surface of approximately 1 % of the graphene admixture where the sudden decrease of resistivity is probably caused by the exceed of percolation threshold is noticeable. It should be noticed that a little smaller amount of percolation threshold (0.5–1 %) was observed in polyurethane composites modified by multi-walled carbon nanotubes (MWCNT), where the significant decrease in resistivity from 2.5 × 1012 Ω m to 5–6 orders of magnitude was observed [Regarding data presented Table 1011 Ω m . The volhe paper , there wSignificantly more cross-linked structure polyurethane/hyperbranched poly(urea-uretane) doped the similar amount of MWCNTs did not show any significant changes in resistivity . It can ε′ (capacitance) and imaginary part of electric permittivity ε″ (dielectric losses) over the whole measurement range of frequency. The obtained parameters ε′ and ε″ for the polyurethane cationomers which have not been doped are approximately 1–2 orders of magnitude higher than the ones registered in the case of the polyurethane anionomers [Having analyzed the obtained FDS characteristics Fig. a, b, it ionomers  as well ionomers  that conα-relaxation occurring in the area of hard urethane segments, which is especially visible in the DSC and DMTA research in the temperature Tg2 in the extent of 25–40 °C. While the low-frequency relaxation β  is relal–Wagner  occurrinσ0, and there was an analysis of observed relaxation processes conducted in tested samples.The parameters of FDS characteristics, estimated with H-N equation for tested polyurethane films are given in Table N = 1 occurring in the equation H-N allows to conclude that in the tested films the ionic conductivity prevails. The increase of the graphene concentration in the range from 0.1 to 2 % results in logarithmic increase of AC conductivity parameter σ0 (conductivity) from 1e−12 Ω−1 m−1 for the undoped material to 4.5e−11 Ω−1 m−1 for 2 % of admixture. It is the process related to the increase of the concentration of ions and the change of structure as well. The admixture of graphene significantly influences the structural relaxation of the material which is observed in prolongation of the relaxation time and the rapid increase of the parameter value τ when amount of admixture exceeds 1 % is visible  for various concentration of graphene in tested polyurethane cationomers. The increase of admixture amount causes the parameter α1 to reach the value of 1, which confirms Debye character of relaxation  and imaginary part of permittivity ε″ (dielectric losses), which can be explained by the high polarity and the phase structure. In the relaxation phenomena in the tested material, there are probably dominant interactions of the dipole–dipole type; therefore, a strong frequency dispersion of constants ε′ and ε″ especially in the range of 10−4–10−1 Hz and significant increase of relaxation time (with the increase of graphene contents) especially at low frequency are observed. The admixture of graphene in the amount 0.5–2 wt.% causes the increase of conductivity and percolation threshold is set on the level of approx. 1 wt.%. The values of constants ε′ and ε″ clearly grow with the increase of graphene amount with the similar shape of frequency dispersion curves as for PU without admixture. There has been the large decrease of PU resistivity in the presence of graphene, which was noncovalent functionalization in THF solvent in the field of ultrasound gives a significant advantage if compared to nonconducting polyurethane compounds obtained with oxide graphene.The research showed that polymer film made from waterborne cationomer polyurethane is characterized with lower volume resistivity, on the level 6.0 × 10


Programmed death 1  and programmed death ligand 1  are involved in generating tumor-associated immunosuppression by suppression of T-cell proliferation and interleukin 2 (IL-2) production and immune checkpoint inhibitors targeting these molecules are showing compelling activity against a variety of human cancers. PD-L1 expression has shown a positive association with response to PD-1 inhibition in non-central nervous system (CNS) tumors, e.g., melanoma or non-small cell lung cancer, and is discussed as a potential predictive biomarker for patient selection in these tumor types. This review summarizes current knowledge and potential clinical implications of PD-L1 expression in glioblastoma. At present, the following conclusions are drawn: (a) functional data support a role for PD-1/PD-L1 in tumor-associated immunosuppression in glioblastoma; (b) the incidence of PD-L1-expressing glioblastomas seems to be relatively high in comparison to other tumor types, however, the reported rates of glioblastomas with PD-L1 protein expression vary and range from 61 to 88%; (c) there is considerable variability in the methodology of PD-L1 assessment in glioblastoma across studies with heterogeneity in utilized antibodies, tissue sampling strategies, immunohistochemical staining protocols, cut-off definitions, and evaluated staining patterns; (d) there are conflicting data on the prognostic role and so far no data on the predictive role of PD-L1 gene and protein expression in glioblastoma. In summary, the ongoing clinical studies evaluating the activity of PD-1/PD-L1 inhibitors in glioblastoma need to be complemented with well designed and stringently executed studies to understand the influence of PD-1/PD-L1 expression on therapy response or failure and to develop robust means of PD-L1 assessment for meaningful biomarker development.  As early as 1863, Rudolf Virchow reported inflammatory infiltrates in tumor tissues and suggested an important link between cancer and the immune system . Cancer-PTEN) gene, gene rearrangements of the PD-L1 gene CD274 or mutations of the 3’-untranslated region (UTR) of the CD274 mRNA and other molecular alterations , 1210, 1Rate of PD-L1-expressing glioblastomas The reported rates of patients with glioblastomas with any PD-L1 protein expression on tumor cells were 61%  in the study by Nduom et al. , 12 and PD-L1 protein expression patterns We found membrane-bound PD-L1 expression on interspersed epithelioid glioblastoma cells in 37.6% of newly diagnosed and 16.7% of recurrent glioblastoma cases  10]. In. In10]. Prognostic role of PD-L1 gene expression CD274) gene of 446 patients using level 2 Agilent microarray gene expression data and found no correlation with patient outcome. In contrast, Nduom et al. , 1210, 1eviously . Overalleviously , 46. Prognostic role of PD-L1 protein levels MGMT promoter methylation status showed the expected separation of prognostic cohorts in this series, thus showing the principal validity of this patient cohort for exploratory survival analyses. There was no correlation with overall survival times for presence or absence of diffuse/fibrillary or membranous PD-L1 expression. Of note, PD-L1 expression on neurons in the infiltrated cortex did not show a correlation with patient outcome, which is in contrast with a prior small study of 17 cases [There are conflicting reports on the prognostic role of PD-L1 protein levels. Berghoff et al.  investig17 cases , 48. MGMT promoter methylation status were not reported. Using the median of 2.77% PD-L1 positive glioblastoma cells they did not find a significant correlation with patient outcome (p = 0.066). However, using a 5% cut-off in a secondary analysis, patients with high PD-L1 expression had significantly shorter survival times (p = 0.086). Nduom et al.  performeThe considerable differences in applied methodology between the studies  and theiPredictive role of PD-L1 expression So far, no clinical trials with PD-1 or PD-L1 inhibitors have been completed in glioblastoma and no data on the predictive role of PD-L1 expression for response to these drugs are available . TestingEmerging clinical studies document compelling antineoplastic activity of immune checkpoint inhibitors including those targeting PD-1/PD-L1 across several tumor types . So far,Antibody 5H1 was kindly provided by Dr. Lieping Chen, Yale University. MP has received honoraria and research support from Bristol-Myers Squibb, Merck Sharp & Dohme, Boehringer Ingelheim, GlaxoSmithKline, Mundipharma, and Roche. ASB has received honoraria and travel support from Bristol-Myer Squibb, Amgen, and Roche. WW has received research grants from Apogenix, Boehringer Ingelheim, Eli Lilly, immatics, MSD, and Roche as well as honoraria for lectures or advisory board participation from MSD and Roche. MW has received research grants from Acceleron, Actelion, Alpinia Institute, Bayer, Isarna, MSD, Merck & Co, Novocure, PIQUR, and Roche and honoraria for lectures or advisory board participation or consulting from Celldex, Immunocellular Therapeutics, Isarna, Magforce, MSD, Merck & Co, Northwest Biotherapeutics, Novocure, Pfizer, Roche, and Teva.