In-situ homogeneous dispersion of noble metals in three-dimensional graphene sheets is a key tactic for producing macroscopic architecture, which is desirable for practical applications, such as electromagnetic interference shielding and catalyst. We report a one-step greener approach for developing porous architecture of 3D-graphene/noble metal (Pt and Ag) nanocomposite monoliths. The resulting graphene/noble metal nanocomposites exhibit a combination of ultralow density, excellent elasticity, and good electrical conductivity. Moreover, in order to illuminate the advantages of the 3D-graphene/noble metal nanocomposites, their electromagnetic interference (EMI) shielding and electrocatalytic performance are further investigated. The as-synthesized 3D-graphene/noble metal nanocomposites exhibit excellent EMI shielding effectiveness when compared to bare graphene; the effectiveness has an average of 28 dB in the 8.2–12.4 GHz X-band range. In the electro-oxidation of methanol, the 3D-graphene/Pt nanocomposite also exhibits significantly enhanced electrocatalytic performance and stability than compared to reduced graphene oxide/Pt and commercial Pt/C. Graphene, a two-dimensional structured carbon material, has captured the attention of the scientific community considerably due to its exceptionally high mechanical strength, ultrahigh specific surface area, and unique conductivity11454510115451671321et al. have reported ultra-light 3D-graphene–based cellular monoliths using a cost-efficient freeze-casting process with ultra-low density, superelasticity, good electrical conductivity, and high-energy absorption efficiencyRecently, three dimensional (3D) graphene assemblies have been used as 2425262728In the present work, we develop a greener, efficient, and low cost one-step approach to large-scale production of 3D-graphene/noble metal (Pt or Ag) nanocomposites by freeze-casting of partly RGO and metal salt solutions. The as-obtained 3D graphene/noble metal (Pt or Ag) nanocomposites were characterized by various spectroscopy studies and correlated with microscopic and surface area analysis. The structure, electrical conductivity, and mechanical properties of as-synthesized 3D-graphene/noble metal (Pt and Ag) nanocomposites were also investigated. The resulting 3D-graphene/noble metal (Pt and Ag) nanocomposites show a combination of ultralow density, excellent elasticity, and good electrical conductivity. Further, the enhanced conductive 3D-graphene/noble metal (Pt and Ag) nanocomposites were extended to EMI studies, in which enhanced conductivity is a necessary criterian. It is interesting that the 3D-graphene/noble metal (Pt and Ag) nanocomposites showed enhanced shielding effectiveness when compared to bare 3D-graphene. In addition, 3D-graphene/Pt nanocomposite is used in electrocatalytic activity study of methanol electro-oxidation. Here, the large and accessible pores of variable sizes helps for quick transportation of reactants to electro-active sites is provided by the 3D-graphene network; in addition, the high electrical conductivity of catalysts are maintained overall. As a result, in the electro-oxidation of methanol, 3D-graphene/Pt nanocomposites show excellent electrocatalytic properties such as a high electrocatalytic performance, abnormal poison tolerance, and dependable stability, which are of a higher grade compared to those of Pt/reduced graphene oxide nanocomposites and commercial Pt/C.2PtCl6.6H2O), and Silver nitrate (AgNO3) were purchased from Sigma-Aldrich. All other chemicals employed were of analytical grade, purchased from Merck Specialties Private Limited, India. Commercial Pt/C  was obtained from Sigma-Aldrich. All the chemicals employed were used as-received without any further purification.Natural graphite powder of a particle size of 45 μm (99.99% purity), Hexachloroplatinate (H2PtCl6.6H2O = 4.5 mg/AgNO3 = 2.5 mg) separately in a cylindrical glass vial of a capacity of 4 ml. To this, ascorbic acid (15 mg) was added and kept in a heating oven at 100 °C for 30 min to get partly reduced GO dispersion and a reduction of metal ions. Each vial was then frozen for 0.5 h in a dry ice bath. After being thawed (at room temperature), the vial was put into a heating oven at 100 °C for 4 h, to further reduce GO to obtain a gel. The gel was then successively subjected to dialysis (to remove dissolved species), freezing drying, and was then dried for 24 h at 50 °C. A detailed schematic representation of the synthesis procedure is presented in the GO aqueous dispersions was prepared by using a reported literature process30λ = 1.541 Å); a Magna-IR spectrometer-50 (Nicolet) was used to record FTIR spectra by a standard KBr pellet method. Raman scattering was performed by a RAM HR 800 Micro laser Raman system with a 519 nm Ar+ laser. The chemical states and surface compositions of the as-synthesized samples were analyzed using XPS . The morphology of the samples was examined by HRTEM using the Phillips-CM 200 electron microscope. The composition of the as-prepared samples was analyzed by an ICP-AES . The specific surface area, pore volume and size distribution of as-synthesized samples were analyzed by Micromeritics instrument ASAP 2020, and the specific surface areas were determined by the multipoint Brunauer−Emmet−Teller (BET) method. The samples were degassed at 60 °C for 4 h, before the analysis. Cylindrical-shaped (~10 mm in height and ~12 mm in dia.) samples were prepared for electrical conductivity measurements and compressive tests. A broadband dielectric spectrometer (Novocontrol) with an Alpha-A frequency analyzer were used to study the AC conductivity of the as-synthesized samples in the frequency range of 1 Hz to 10 MHz. Conductivity measurements were carried out by putting the samples in between the gold-plated copper electrodes. The compressive tests were executed in an Instron  that utilized a load cell (10 N) and had a strain rate of 100% per minute. EMI shielding properties were measured by using PNA Network Analyzer N5222A (Agilent) in the X-band. Catalyst ink was prepared by dispersing 5 mg of each catalyst in a mixed solution of 5 mL of Millipore water, 1 mL of iso-propanol, and 10 μL of Nafion® solution under sonication for 20 min. The 20 μL of the catalyst ink (well dispersed) was drop-casted on the glassy-carbon electrode (0.07 cm2), named as the modified glassy-carbon electrode. Potentiostat/Galvanostat Autolab-302N with GPES 4.9 software was used for the electrochemical measurements. Electrochemical measurements were conducted in a three-electrode system. A platinum wire and a saturated calomel electrode (SCE) were used as counter electrode and reference electrode, respectively. A modified glassy-carbon electrode (3 mm diameter) was used as a working electrode. All the measurements were executed at room temperature. The volumetric solution was purged with high purity nitrogen gas for 5–15 min before an electrochemical scan. All the electrochemical potentials are reported against the reversible hydrogen electrode (RHE) in the manuscript.The structural examination of as-synthesized specimens were performed by using a Powder XRD diffractometer (Philips PW 3040/60) with Cu Kα radiation  nanocomposites by using a low cost wet shaping technique, which generally called freeze casting. In this process, phase separation took place between the solid particles and forming ice, and the rejected particles mounted up between the developing ice templates3228303334353637et al. groupGO and metal salt solution in presence of ascorbic acid produced 3D porous assemblies in freeze-casting process. To understand the mechanism, a control experiment was conducted by using a reported processXRD was used to explicate the phases and structural parameters of the as-synthesized GO and 3D-graphene/noble metal (Pt and Ag) nanocomposites samples; the results are shown in −1, and shifted to 1577, 1579 and 1580 cm−1 for the bare 3D-graphene, 3D-graphene/Pt and 3D-graphene/Ag respectively, which is close to the value of pristine graphene  is correlated with the change in the average size of the sp2 domains. The ID/IG ratios for GO, bare 3D-graphene, 3D-garphene/Pt and 3D-graphene/Ag nanocomposites are calculated to be 0.82, 1.1, 1.11 and 1.13 respectively. The increase in ID/IG ratios of bare 3D-graphene, 3D-garphene/Pt and 3D-graphene/Ag nanocomposites than GO indicated that the decrease in the average size of the sp2 domains. Even, the created new sp2 domains of reduced GO are smaller in size than the ones which is present in GO before reductionRaman spectroscopy is extensively used to observe the electronic and structural properties in carbonaceous materials. graphene . The shi−1 (O-H stretching), 1730 cm−1 (C=O stretching vibration of the COOH groups), 1405 cm−1 (O-H deformation vibration of tertiary C-OH), 1222 cm−1 (C-O stretching vibration of phenolic C-OH), and 1045 cm−1 (C-O stretching vibrations of epoxy groups). The band at 1612 cm−1 is related to the bending vibration of the adsorbed water molecules or skeletal vibrations of unoxidized C-C bonding−1 respectively. The shifting of the stretching vibration peaks towards lower wave number with increase in mass of the noble metals suggested the chemical interaction of metal ions with the graphene sheets. Also, O-H bending vibration peaks of adsorbed water molecules was become more prominent in 3D-graphene/noble metal nanocomposites and shifted to lower wave number with increasing the mass of noble metals. The O-H bending vibration peaks of H2O are observed at 1612, 1568 and 1572 cm−1 for GO, 3D-graphene/Pt and 3D-graphene/Ag monoliths respectively. The significant shifting of wave number towards lower side in 3D-graphene/noble metal nanocomposite might be due to the chelation of water molecules with the noble metals.The FTIR spectras of the as-prepared 3D-graphene–based noble metal (Pt and Ag) nanocomposites along with GO are shown in 2 carbon peak (284.5 eV), the intensities of the various oxygenic functional groups and the intensity of the sp3 carbon peak (285.1 eV) were effectively reduced in the case of the 3D-graphene/Pt nanocomposite. It was further confirmed that GO was successfully reduced to graphene in the 3D-graphene/Pt nanocomposite through the freeze-casting method. 5/2 and 4f7/2). The most intense doublet Pt 4f peaks at 71.1 eV (4f7/2) and 74.6 eV (4f5/2 ) are assigned to metallic Pt0, whereas the second doublet Pt 4f peaks at 72.1 and 77.51 eV are assigned to PtII. The appearance of PtII could arise from the partial oxidation of Pt0 on the graphene surface. Moreover, from 2 carbon of graphene via oxygen (Pt-O-C)5/2 and Ag 3d3/2 respectively, and suggested that the presence of metallic Ag0The surface chemistry of the GO, 3D-graphene/Pt and 3D-graphene/Ag nanocomposites was investigated by XPS analysis. The surface morphologies of the 3D-graphene/noble metal nanocomposites were examined by FEG-SEM. 6 Hz due to the incorporation of noble metal (Pt and Ag) particles in the 3D-graphene nanosheets. The real part of AC conductivity was derived by complex conductivity using the relation:where dc is the frequency-independent conductivity or dc conductivity (at ω=0), and A is the temperature-dependent constant. The addition of noble metal particles in 3D-graphene shows a prominent increase in conductivity, indicating frequency-independent behavior. The AC conductivity (σ′ (ω)) is almost constant over the frequency in 3D-graphene/Ag and 3D-graphene/Pt nanocomposites, which is ascribed to the dc conductivity, in which the electrode polarization is negligible. A similar type of behavior was observed in carbon nanotube-based composites earlierwhere ω is the angular frequency, exponent s is the function of frequency and is limited to 0.7 to 0.9. σThe dispersion of noble metal (Pt and Ag) particles on the 3D building blocks of nanosheets increases the conductivity to 0.032 S/cm in 3D-graphene/Ag and 0.01 S/cm in 3D-graphene/Pt nanocomposites. The electrical conductivity of 3D-graphene/noble metal nanocomposites (Ag and Pt) was significant to the compressed graphene nanosheets and graphite oxide reported earlier43The compression test of 3D-graphene/noble metal (Pt and Ag) nanocomposite at 50% strain was investigated to identify the stress-strain behavior under cyclic loading. The 3D-graphene/noble metal (Pt and Ag) nanocomposite was compressed to up to 50% strain under pressure; it recovered its original shape immediately after the pressure was released . The com50In support of conductive studies, the electromagnetic interference shielding properties of 3D-graphene and 3D-graphene/noble metal nanocomposites were studied in the X-band (8.2–12.4 GHz) by measuring shielding parameters using a vector network analyzer . The shi53PI corresponds to input power, and PT corresponds to Transmit powers.where where The shielding properties of 3D-graphene/noble metal nanocomposites were compared with the host 3D-graphene. The total SE in the composites is mostly dominated by the absorption phenomenon. It is interesting that the 3D-graphene/Ag nanocomposite showed better shielding properties than 3D-graphene/Pt and 3D-graphene. The SE of 28 dB for the 3D-graphene/Ag nanocomposite put forward a shielding power of ~99.6% in an average film thickness of 0.8 mm. Additionally, 3D-graphene/Pt showed an enhanced SE of 24 dB compared 3D-graphene (~18 dB). The total SE by the absorption phenomenon is mainly due to the interaction of electric dipoles with the electromagnetic field of radiation and the functional groups of functionalized 3D-graphene attained by the addition of noble metal  particles. Thus, the incorporation of fillers in the 3D-graphene plays an important role for improving the structure and electrical conductivity, which also revealed by our earlier studySE in terms of permittivity (ε), conductivity (σ′) and permeability (μ′) is expressed as:There by suggesting that the proportionate increase in conductivity in the 3D-graphene/Ag nanocomposite leads to substantial enhancement in the shielding effectiveness. Similar results have been reported earlier, in which carbon foam was embedded with Ni particles to improve the shielding properties2SO4. The CVs are scanned from −0.2 to 1.0 V with a scan rate of 50 mV s−1 in the 0.5 M solution of H2SO4 (N2-saturated). It has been observed that there are three potential regions on CVs of the commercial Pt/C (20 wt%), the RGO/Pt nanocomposite and the 3D-graphene/Pt nanocomposite. The first potential region from −0.2 to 0.05 V presents adsorption/desorption of hydrogen. The 2nd potential region from 0.1 to 0.3 V indicates the double layer capacitance region. The 3rd potential region from 0.4 to 0.9 shows the metal oxidation/reduction region. The 3D-graphene/Pt nanocomposite shows higher double–layer capacitance when compared to commercial Pt/C and the RGO/Pt nanocomposite. This is because of the larger surface area of the 3D-graphene as compared to the RGO and carbon black. The larger surface area of 3D-graphene is confirmed by the Brunauer-Emmett-Teller (BET) surface area analysis, which indicates that the specific surface area of the carbon black, RGO and 3D graphene are 94, 122 and 155 m2/g  and 36% more than that of the RGO/Pt nanocomposite (15.2 m2/g). The higher ESCA of Pt in the 3D-graphene/Pt nanocomposite may be due to the homogenous distribution of the Pt nanoparticles on the 3D-graphene (as indicated in TEM) and the distinct structure of 3D-graphene .In order to explore the potential application of 3D-graphene/noble metal nanocomposites as an electrocatalysts further, we have selected the 3D-graphene/Pt nanocomposite to study its catalytic activity in methanol oxidation. 155 m2/g , respectf) to the backward-scan peak current (Ib) that is, If/Ib value59f/Ib value for Pt/C, RGO/Pt, and 3D-graphene/Pt are 0.85, 1.06, and 1.3 respectively, signifying that the 3D-graphene/Pt nanocomposite has higher efficiency in the methanol oxidation in the forward direction.The electrochemical activities of the commercial Pt/C (20 wt%), RGO/Pt nanocomposite and the 3D-graphene/Pt nanocomposite were compared by CV for the oxidation of methanol, and the subsequent results are presented in the 56573OH and 0.5 H2SO4 for 2000 s. The initial current decay in all cases is due to the development of double layer capacitance. Subsequently, the current decays slowly, which can be attributed to the adsorption of a small amount of carbon monoxide (COads) species on the surface of the catalyst during electro-oxidation of methanol42− species on the surface of the catalysts, which inhibits the reaction active sites of the catalystsThe long-term catalytic activities of the Pt/C, RGO/Pt nanocomposite and the 3D-graphene/Pt nanocomposite were examined by a steady-state chronoamperometry measurement. In this study, we have demonstrated a general and clean method to fabricate 3D-graphene/noble metal (Pt and Ag) nanocomposites built from partially reduced graphene oxide and metal precursors using a facile and cost-effective freeze-casting method. The as-synthesized 3D-graphene/noble metal (Pt and Ag) nanocomposites consisted of a highly interconnected porous structure and exhibited enhanced mechanical properties and conductivity due to the incorporation noble nanoparticles (Pt and Ag) in the 3D-graphene building block. Their electrocatalytic performance and electromagnetic interference (EMI) shielding effect has been further investigated. The as-synthesized 3D-graphene/noble metal (Pt and Ag) nanocomposites exhibit an excellent EMI shielding effectiveness when compared with bare 3D-graphene, and can be used for electromagnetic radiation or as a radar-absorbing material in civil and military applications. Electrocatalytic activity of the 3D-graphene/Pt nanocomposite in methanol oxidation has been demonstrated, which shows high electrocatalytic activity, reliable stability and abnormally high poison tolerance compared to the RGO/Pt nanocomposite and Pt/C. The resulting 3D-graphene/noble metal (Pt and Ag) nanocomposites with highly interconnected micro and macro porous structures, and good electrical, mechanical and catalytic activities hold considerable promise of a new pathway for application in photocatalysis, pressure sensors, actuators, and electrode materials.How to cite this article: Sahoo, P. K. et al. Ice-templated synthesis of multifunctional three dimensional graphene/noble metal nanocomposites and their mechanical, electrical, catalytic, and electromagnetic shielding properties. Sci. Rep.5, 17726; doi: 10.1038/srep17726 (2015).


During the growth process, defects such as vacancies are unavoidably present at the interface between graphene and h-BN. In the present work, typical vacancy defects, which were located at the interface between graphene and h-BN, were studied by density functional theory. The interface structure, mechanical and electronic properties, and failure behavior of the hybrid graphene/h-BN sheet were investigated and compared. The results showed that the formation energy of the defective graphene/h-BN interface basically increased with increasing inflection angles. However, Young’s modulus for all graphene/h-BN systems studied decreased with the increase in inflection angles. The intrinsic strength of the hybrid graphene/h-BN sheets was affected not only by the inflection angles, but also by the type of interface connection and the type of defects. The energy band structure of the hybrid interface could be tuned by applying mechanical strain to the systems. These results demonstrated that vacancies introduced significant effects on the mechanical and electronic properties of the hybrid graphene/h-BN sheet.Hybrid graphene/ Discontinues, such as vacancies, fault lines and cracks, are unavoidably present near and along the graphene/h-BN interface to reduce elastic strain energy. As we know, the atoms in the defect are not in perfect crystalline arrangement. The mechanical properties of this hybrid material may be further affected and may give rise to large impact on the performance of devices based on such material. Vacancies are one of the most popular point defects on two-dimensional (2D) material surface. Similar to graphene and some other graphene-like materials2728h-BN interface should serve as fracture nucleation center under high tension load. Their mechanical properties are more complicated due to the existence of two different types of atomic lattices. It is therefore worthwhile to study the possible relationship between the mechanical properties of graphene/h-BN and the defect parameters. However, recent experimental and theoretical studies focused on the patterns, electronic and thermoelectric properties of the graphene/h-BN interface303132h-BN interface.More recently, using scanning tunneling microscopy (STM), Loh and co-workers clearly observed discontinues and dislocations along the interface of a graphene/h-BN sheet. In particular, the perfect interface and interfaces with typical vacancy defects located along the interface were studied by density functional theory (DFT). The interface structure, defect formation energy, mechanical properties, changes of the energy band during tensile process, and failure behavior of the hybrid graphene/h-BN interface with and without defects were studied and compared.The present work aims to investigate the potential effect of the interface on the mechanical properties and failure behavior of the hybrid graphene/h-BN sheet was investigated using DFT method. Generalized gradient approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) function was chosen to describe the graphene/h-BN interfaceh-BN surface to minimize the influence between adjacent layers. In addition, the distance between adjacent interfaces was set as more than 20 Å to minimize the influence between them. Å 10 × 10 × 1 k-point mesh was set up during the geometry equilibrium with all the atomic structure parameters fully relaxed. All calculations were realized using the DMol3 module (Accelrys Inc.).The mechanical properties and failure behavior of the interface of hybrid graphene/h-BN domains could form an interface with either a zigzag linking edge or an armchair linking edge. In the present work, both the zigzag edge interface (G-BN-zz) and armchair edge interface (G-BN-am) between graphene and h-BN domains were considered  zigzag shape, its adjacent interface edge possesses a carbon-nitrogen (C-N) configuration.As reported by previous experimental observationsFor either the zigzag interface or the armchair interface, six typical vacancy defects located at the interface were selected as probes to analyze the effects of vacancies on the mechanical properties and failure behavior of the interfaces. Due to the combinations of single atom vacancies (SV) or double atom vacancies (DV), the interface may turn into different line defects. The nomenclature and structure of the defect models are shown in h-BN sheets with defects usually exhibit a slight warping. To reflect the structural changes of graphene/h-BN interface due to the vacancy defects, inflection angle was defined  angles, C-C bonds and B-N bonds were observed on the hybrid graphene/h-BN interface without defects (for both the zigzag and armchair edge interface).As shown in  defined  and collh-BN surface.For the C-B zigzag interface with vacancies, the maximum elongation (3.8%) of C-B bond relative to the system without defects occurred at the vacancy of the zz-SV(CB)-B system; while for the C-N zigzag interface with vacancies, the maximum change (2.8%) of C-N bond was found at the interface of zz-SV(CN)-N system. When comparing the system with defects and an armchair interface without defects, the changes of C-B and C-N bonds were up to 13.3% and 2.9%, respectively. The maximum elongation of the C-B bond appeared at the interface of the am-SV-B system; while that of the C-N bond was found at the interface of the am-SV-C(B) system. Due to the dangling bond around the vacancies, several atoms (N or B) around the vacancies exhibited a slight elevation (0.35 Å to 0.58 Å) from the graphene/h-BN interface. It can be expressed as45Formation energy was introduced to describe the thermodynamic stability of the vacancies on the hybrid graphene/Etotal and EG−BN are the energies of the hybrid graphene/h-BN sheet with and without vacancies, respectively. μC, μB and μN denote the increased (n > 0) or decreased (n < 0) chemical potential of carbon, boron and nitrogen atoms, respectively. L is the periodic length along the interface line. Formation energies of all the graphene/h-BN systems are shown in h-BN interfaces with defects ranged from 6.3 eV to 14.4 eV, which were comparable to that of the defect on pristine graphene and h-BN sheet4where h-BN interface basically increased with increasing inflection angles. Actually, graphene/h-BN interfaces with SV defects exhibited relatively lower formation energies  of that for graphene (h-BN), while that of the armchair edge interface reduced to 72.0% (86.2%) of that for graphene (h-BN)  see . Thus, th-BN systems basically decreased with increasing inflection angle. The relatively flat interface, such as BN-G-am (744 GPa) and am-SV-C(B) (700 GPa) systems, has the highest Young’s modulus amongst all systems. When the inflection angle of the interface reaches more than 20°, Young’s modulus of the systems significantly decreases to less than 70% of that of the graphene/h-BN interface without defects. The fitted line in As shown in τ0 = 761 GPa is the approximate highest Young’s modulus of the graphene/h-BN interface without defects. Obviously, the warpage of graphene/h-BN interface significantly decreases the Young’s modulus of this hybrid material. As we know, a curved surface is usually easier to be deformed than a completely flat surface, as the initial deformation for a curved surface was the spreading of the surface rather than the elongation of the chemical bonds. Thus, the higher the inflection angle, the easier the deformation to occur at the graphene/h-BN interface.where h-BN interface with and without defects show obvious brittle fracture characteristic  and nearly equal to that of the prinstine h-BN . The graphene/h-BN armchair interface possessed an intrinsic strength of 95 GPa, which was 13% higher than that of the zigzag interface.The morphology of stress-strain curves for both the graphene/stic see , i.e., rh-BN) sheet with grain boundaries on the surface showed an obvious linear relationship with the inflection angles of the surface, i.e., the intrinsic strength basically showed linear decrease with the increase of the inflection angles. As shown in h-BN sheet, although the increase of the inflection angles affect the intrinsic strength of the defective systems to a certain extent, no clear linear relationship was found between the intrinsic strength and the inflection angles. The warpage of the graphene/h-BN sheet might decrease the strength of the surface as a larger inflection angle effectively causes a 2D surface to become more bulk, which is close to its 3D structures. Nevertheless, apart from the strength decrease, other factors may also affect the strength of the system.As reported in previous works4After a careful analysis of the results, it was found that for the models with defects and a zigzag edge interface, the intrinsic strength showed close relationship with the type of the interface (C-B edge or C-N edge) where the vacancies were located at. Vacancies which were located at the C-B edge introduced more detrimental effect on the intrinsic strength of the systems than that located at the C-N edge shown in . As the h-BN interface without defects and much lower than that of the pristine graphene or h-BN.The critical failure strain corresponding to the intrinsic strength ranged from 12% to 8% for the defective models with a zigzag edge interface and 14% to 9% for the defective models with an armchair edge interface, respectively. These values were comparable with the critical failure strain of the graphene/h-BN sheet. So, the relationship between the intrinsic strength, the critical failure strain and the linear density of the vacancies along the interface was studied. With limited computing resource, just one type of vacancy defect was selected on each interface edge, i.e., single carbon vacancy on the zigzag (C-B) edge interface and single nitrogen vacancy on the armchair edge interface. As shown in h-BN interface.For the following discussion, we define the defect degree of vacancies as the linear density of the vacancies along the interface. It is desirable to reflect the influence of the defect degree of the interface on the strength of the graphene/On the other hand, the relationship between the inflection angles and the defect density based on the analysis of these two defect types were discussed. The inflection angles were summarized in h-BN interface due to the tensile load, the configuration of the interfaces with different strains were observed. The fracture process for several typical interfaces with defects was collected in h-BN sheets occurred at or near the interface, which indicated that the interface had weak mechanical strength of such material. For a zigzag interface without defects, the fracture appeared on the C-B interface rather than the C-N interface, as a C-N bond possessed shorter bond length and higher interaction energy than a C-B bond. When the vacancies were located at the C-B interface, still the C-B interface fractured with the elongation of C-B bonds under tensile load  the defect-free graphene/h-BN systems with the zigzag edge interface; (ii) the defect-free graphene/h-BN systems with armchair edge interface; (iii) the zz-SV(CB)-C system with a carbon vacancy defect at the graphene/h-BN (C-B) interferce; (iv) the am-SV-N system with a nitrogen vacancy defect at the graphene/h-BN interface. For each model, the electronic band structure of the system in the absence of mechanical strain and that with mechanical strain closed to its critical failure strain, were calculated and analyzed.Pioneer researches have demonstrated that mechanical straining can alter the band gaps of graphene nano-ribbons significantly3637The energy band figures were collected in the h-BN sheet, which were located at the interface between graphene and h-BN domains, were studied by DFT method. The interface structure, mechanical properties, changes of the energy band during tensile process, and failure behavior of the hybrid graphene/h-BN sheet were investigated and compared. The results showed that the formation energy of the defective graphene/h-BN interface basically increased with increasing inflection angle. While Young’s modulus for all of the graphene/h-BN systems decreased with increasing inflection angle. The intrinsic strength of the hybrid graphene/h-BN sheets was affected not only by the inflection angles but also by the type of the interface connection and the type of the defects. The electronic properties of the hybrid interface might be affected significantly by the mechanical strain. The information obtained in this work would provide fundamental information for the application of the hybrid graphene/h-BN materials in nano-devices.In summary, twelve important typical vacancy defects of the hybrid graphene/How to cite this article: Ding, N. et al. Mechanical properties and failure behaviors of the interface of hybrid graphene/hexagonal boron nitride sheets. Sci. Rep.6, 31499; doi: 10.1038/srep31499 (2016).


Spontaneous cancers are common diseases in dogs. Among these, some malignant cancers such as oral melanoma, osteosarcoma, hemangiosarcoma, and mast cell tumor are often recognized as clinical problems because, despite their high frequencies, current treatments for these cancers may not always achieve satisfying outcomes. The absence of effective systemic therapies against these cancers leads researchers to investigate novel therapeutic modalities, including immunotherapy. Programmed death 1 (PD-1) is a costimulatory receptor with immunosuppressive function. When it binds its ligands, PD-ligand 1 (PD-L1) or PD-L2, PD-1 on T cells negatively regulates activating signals from the T cell receptor, resulting in the inhibition of the effector function of cytotoxic T lymphocytes. Aberrant PD-L1 expression has been reported in many human cancers and is considered an immune escape mechanism for cancers. In clinical trials, anti-PD-1 or anti-PD-L1 antibodies induced tumor regression for several malignancies, including advanced melanoma, non-small cell lung carcinoma, and renal cell carcinoma. In this study, to assess the potential of the PD-1/PD-L1 axis as a novel therapeutic target for canine cancer immunotherapy, immunohistochemical analysis of PD-L1 expression in various malignant cancers of dogs was performed. Here, we show that dog oral melanoma, osteosarcoma, hemangiosarcoma, mast cell tumor, mammary adenocarcinoma, and prostate adenocarcinoma expressed PD-L1, whereas some other types of cancer did not. In addition, PD-1 was highly expressed on tumor-infiltrating lymphocytes obtained from oral melanoma, showing that lymphocytes in this cancer type might have been functionally exhausted. These results strongly encourage the clinical application of PD-1/PD-L1 inhibitors as novel therapeutic agents against these cancers in dogs. Dogs often develop spontaneous cancers, which may cause death  or reducImmunotherapies have potential as novel treatment options for cancer. Among those, immune checkpoint inhibitors such as anti-programmed death 1 (PD-1) and anti-PD-ligand 1 (PD-L1) antibodies showed promising effects on several malignancies in humans ,7. The iHowever, there are only few reports on the PD-1/PD-L1 axis in dogs, and its association with diseases remains to be elucidated. Previously, we have reported that PD-L1 is expressed in dog melanoma, MCT, and renal cell carcinoma and that PD-L1 blockade by an anti-PD-L1 antibody enhances IFN-γ production by tumor-infiltrating cells . These rAnimal use throughout this study was approved by the Institutional Animal Care and Use Committee , Hokkaido University. No animal was sacrificed for the purpose of this study. Clinical samples of dog tumor tissues were surgically excised at the Veterinary Teaching Hospital, Graduate School of Veterinary Medicine, Hokkaido University and at Veterinary Hospitals in Sapporo city in 2014–2015. Upon the use for this study, informed consent was obtained from all owners of the dogs. Peripheral blood samples of clinically healthy dogs were collected from beagles at the age of 12–15 years kept at the Experimental Animal Facility, Graduate School of Veterinary Medicine, Hokkaido University.To assess the binding specificity of a recently established anti-PD-L1 monoclonal antibody (mAb) , flow cy+ cells or CD8+ cells was evaluated.To assess whether PD-1 expression is upregulated in the context of canine cancers, flow cytometric analysis was performed with cross-reactive anti-human PD-1 antibody . Periphen = 40) used in this study originated from the oral cavity. The MCT samples (n = 5) were all classified into Patnaik grade III [n = 5) analysis, no inflammatory mammary carcinoma samples were included. In addition to the above-mentioned specimens, OS (n = 10), HSA (n = 10), prostate adenocarcinoma (n = 5), skin squamous cell carcinoma (n = 5), diffuse large B-cell lymphoma (n = 5), nasal adenocarcinoma (n = 5), soft tissue sarcoma (n = 5), histiocytic sarcoma (n = 5), transitional cell carcinoma (n = 5), and anal sac gland carcinoma with metastatic disease (n = 5) specimens were studied by immunohistochemistry.Specimens were randomly selected from formalin-fixed and paraffin-embedded tissues of dog malignant tumors , which had been submitted for histological diagnosis and kept in a commercial pathology laboratory . All the melanoma samples  procedure. Sections (4 μm) were dewaxed in xylene and hydrated through graded alcohols. To remove endogenous peroxidase, the sections were immersed in a 3% hydrogen peroxide solution at room temperature for 10 min. Following this, the sections were incubated with anti-PD-L1 antibody 6G7-E1 (10 μg/mL). After washing with phosphate-buffered saline, the sections were incubated in a secondary antibody solution (biotin-labeled goat anti-rat IgM)  at room temperature for 30 min. Following the incubation, the sections were reacted using the ABC in the VECTASTAIN Elite ABC Kit  at room temperature for 30 min. Visualization was accomplished using a 0.05% 3,3′-diaminobenzidine solution. Mayer’s hematoxylin stain was used as a counterstain. For the negative control, sections were subjected to the same procedures without the primary antibody or with the rat IgM isotype control antibody . The specimen was considered positive for PD-L1 if there was histologic evidence of cell staining. No obvious staining was observed in the negative control sections . To prepp < 0.05 was considered to be statistically significant.In the flow cytometric analysis of PD-1 expression, Mann–Whitney U test was conducted and The anti-PD-L1 antibodies that can bind to dog PD-L1 were established previously ,17. AmonImmunohistochemical analysis was performed to detect PD-L1 expression in various malignant cancers. In total, 110 specimens were tested, among which 36 oral melanoma, 7 OS, 6 HSA, 3 grade III MCT, 4 mammary adenocarcinoma, and 3 prostate adenocarcinoma specimens were PD-L1 positive Figs . Both cy+ and CD4+ TILs from oral melanoma (p < 0.05). The positive rate of PD-1 expression on CD8+ or CD4+ TILs was 70.9–96.6% or 80.2–96.8%, respectively Click here for additional data file.S2 FigTILs obtained from (A) hepatocellular adenoma and (B) hepatocellular adenocarcinoma were analyzed for PD-1 expression by flow cytometry (red line). Normal tissue-infiltrating lymphocytes (NILs) obtained from adjacent healthy liver tissue of the same individuals (blue line) were used as control. Black line, isotype control for TILs. Shaded area, isotype control for NILs.(TIF)Click here for additional data file.


Sarcoidosis is an idiopathic multisystem disease characterized by the formation of noncaseating granulomas. It frequently presents with pulmonary infiltrates and bilateral hilar and mediastinal lymphadenopathy. Splenic involvement is common, but massive splenomegaly is a rare occurrence. Sarcoidosis is known as “the great mimicker” (or “the great imitator”) since it exhibits a myriad of symptoms, mimicking other inflammatory, infectious, and neoplastic conditions, including lymphoma. Herein, we report the case of a 44-year-old male patient who was found to have bicytopenia, hypercalcemia, diffuse lymphadenopathy, and massive splenomegaly, a constellation of findings suggestive of underlying lymphoma. Interestingly, lymph node biopsy showed noncaseating granulomas suggestive of sarcoidosis, without evidence of malignancy. Sarcoidosis is a chronic inflammatory disorder of unknown origin which occurs mainly in young people , 2. It iThe symptoms of sarcoidosis, if present, are nonspecific. The presence of noncaseating granulomas is also not pathognomonic of the disease, as it can be seen in malignancy . MoreoveHerein, we report the case of a 44-year-old male patient who was found to have bicytopenia, hypercalcemia, diffuse lymphadenopathy, and massive splenomegaly, a constellation of findings suggestive of underlying lymphoma. Surprisingly, lymph node biopsy showed noncaseating granulomas suggestive of sarcoidosis, without evidence of malignancy.We report the case of a 44-year-old Caucasian male who was referred to our hospital by his primary physician for abnormal outpatient laboratory test values. The patient had been healthy until 5 months prior to admission, when he started to have progressively worsening fatigue. Outpatient blood tests revealed kidney injury, hypercalcemia, and anemia, findings that required hospitalization.On the day of admission, the patient's only complaint was severe fatigue. Upon further questioning, he admitted having a 70-pound unintentional weight loss over the last 18 months. He denied any fever, chills, night sweats, cough, rash, or joint or abdominal pain. His prior medical history consisted of diabetes mellitus, gout, and hyperlipidemia. The patient was a nonsmoker and had no allergies. His family history was noncontributory.On physical exam, the patient's body temperature was 98.6°F, blood pressure was 159/92 mmHg, and heart rate was 100/min. Cardiovascular and pulmonary exams were unremarkable. Left upper quadrant tenderness was noted on the abdominal exam, as well as a firm and enlarged spleen, which was palpable below the umbilicus. No rash, cervical, or axillary lymphadenopathy was identified.μm3. The rest of the hematologic panel was as follows: white blood cell count of 3.93 × 109/L, platelet count of 254 × 109/L, and erythrocyte sedimentation rate (ESR) of 93 mm/h. A peripheral blood smear was within normal limits. In addition, hypercalcemia of 13.7 mg/dL was noted, along with a blood urea nitrogen (BUN) of 33 mg/dL and a serum creatinine of 2.39 mg/dL, findings consistent with kidney injury. The renal function was normal three years ago. Liver enzymes were normal. An abdominal sonogram showed a markedly enlarged and diffusely heterogeneous spleen measuring 30 cm in length  of 82.3 n length . Enlargen length , along wn length . A chestThe patient received packed red blood cells transfusions to maintain his hemoglobin level around 8 mg/dL. He was also given intravenous fluids to treat the hypercalcemia and received one dose of pamidronate, which helped to lower the calcium level to as low as 11 mg/dL over the next few days.2 levels (with low PTH levels). Anti-nuclear antibody, HIV test, monospot test, and purified protein derivative (PPD) were negative. Additional studies are listed in The presence of massive splenomegaly and diffuse lymph node enlargement was concerning lymphoma. Further workup showed anemia of chronic disease and elevated vitamin D 1,25(OH)Four weeks after the initiation of therapy, the patient's calcium level was 10.3 mg/dL, along with a hemoglobin of 9.4 g/dL and a creatinine of 1.38 mg/dL. 2 weeks later, ACE level was 31 mg/dL. 8 weeks after hospital discharge, a fluorine-18 fluorodeoxyglucose (FDG) PET imaging, done while the patient was still on treatment, showed no focal FDG avid lesions, along with stable non-FDG avid thoracic and abdominal adenopathy. The patient continued to be in good health 9 months after his diagnosis and had shown no progression of sarcoidosis.Sarcoidosis is a chronic idiopathic granulomatous disease which can affect all age groups . It has Sarcoidosis can be asymptomatic in some patients. If present, symptoms are both systemic  and/or organ-specific  . There iThe diagnosis of sarcoidosis is based on criteria from the American Thoracic Society (ATS), the European Respiratory Society (ERS), and the World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) . These cSome patients with sarcoidosis are not disabled by the illness and therefore do not require treatment . In gene Myelofibrosis (primary or secondary). Chronic myeloid leukemia. Lymphoma . Hairy cell leukemia. Gaucher disease. Amyloidosis. Beta thalassemia major. Schistosomiasis. Kala-azar . Sarcoidosis (rarely). Hyperreactive malarial splenomegaly syndrome . AIDS with mycobacterium avium complex. Splenic vein thrombosis.Splenic involvement in sarcoidosis is defined as the histologic presence of noncaseating granulomas in the spleen. Autopsy studies show that the spleen is the second most commonly affected organ in sarcoidosis, with the lung being first . ClinicaSplenic involvement in sarcoidosis is usually asymptomatic, although left upper quadrant pain is occasionally present. Patients with splenomegaly may have a higher incidence of constitutional symptoms and more disseminated disease . SplenicThe crux of sarcoidosis is its ability to masquerade as other diseases, most significantly lymphoma. As such, for clinicians, distinguishing these entities can make the difference between life and death for patients. In addition to the nonspecific clinical, radiological, and histological features in sarcoidosis, the lymphocyte activation and the reticuloendothelial system involvement  make the distinction of sarcoidosis from lymphoma extremely challenging. In fact, hypercalcemia and increased serum ACE levels have also been described in patients with lymphoma . MoreoveIn some cases, the coexistence of “true” sarcoidosis and lymphoproliferative disease has been reported in the literature. In most of these cases, sarcoidosis preceded the diagnosis of lymphoma, but in few other reports, lymphoproliferative disease occurred first . This poFDG PET imaging remains an essential modality in the management of lymphoma. One of many advantages it offers over conventional imaging is the ability to detect occult lesions. However, its specificity is limited by multiple false-positive conditions, including infections, inflammations, and sarcoidosis , 20. In This report illustrates an unusual case of sarcoidosis that presented as bicytopenia, hypercalcemia, diffuse lymphadenopathy, and massive splenomegaly, mimicking lymphoma. Physicians should be aware of this atypical presentation and accordingly should consider sarcoidosis in their differential diagnosis, after excluding other worrisome diagnoses, such as lymphoma.


It is well established that the vast majority of the population favors their right hand when performing complex manual tasks. However, the developmental and evolutionary underpinnings of human manual asymmetries remain contentious. One often overlooked suggestion is that right handedness may stem from an asymmetrical bias in attention, with the right hand being allocated more attentional resources during bimanual tasks than the left hand . This re Approximately 90% of humans consider themselves to be right handed . This unThe goal of this article is to provide an overview of the evidence for a rarely discussed hypothesis – that right handedness is a consequence of a rightward attentional bias. Proponents of this hypothesis claim that when attention must be divided between the hands during bimanual tasks, most individuals will allocate the majority of their attentional resources to the right hand or its task. First, we describe the evidence for an automatic link between the attentional system and manual actions. Next, we present the empirical studies which have found evidence for a rightward attentional bias in right-handed individuals’ during rhythmic and discrete bimanual tasks. Finally, we discuss the viability of the attentional bias explanation as a way to bridge the gap between performance and selection asymmetries.On the face of it, there would seem to be obvious advantages to having two equally skilled hands to complete twice as many tasks. Such a strategy, however, would not be easily compatible with humans’ attentional limitations: prior to commencing a typical reach toward a visual target, a saccade is used to aim the high-resolution foveal portion of the eye to the region of interest . AlthougThe link between attention and action in the context of physiology and neuropsychology is well-studied in the context of sequential unimanual movements  the right hand of right handers. However, these findings offer little insight into the causal relationship between attentional and manual asymmetries. Clearly, altering one’s hand preference is not simply a case overtly attending toward the non-dominant hand . It is, The attentional bias hypothesis posits that attention is biased toward the right hand in a substantial proportion of the population from birth , 1994. TWhile the link between consistent right hand selection and right hand performance advantages is easy to understand, it is worth considering why an attentional asymmetry is necessary in human motor coordination. Peters suggests that the key to the attentional bias hypothesis is bimanual coordination – the common factor linking the experiments described in this review. The ‘kinematic chain’ hypothesis, proposed by Another point which is worth consideration is how to reconcile the rightward attentional bias which right handers exhibit during bimanual tasks with the oft-reported left hand unimanual reaction time advantage during unimanual localization tasks , which mUp until this point, only evidence has been presented from right-handed individuals. The situation for the understudied left handers remains unclear, largely because studies examining adextrals in this context are rare. In fact, they are crucial, if establishing the relationship to cerebral asymmetries is desired see , 1996 noThe underlying cause of human handedness is the cause of much debate. Here, we have presented the evidence for a bias in attention which occurs during bimanual coordination which may drive hand preferences, and presented a plausible account of how this bias would lead to manual asymmetries across the population. Future work on relating these effects to cerebral asymmetries in right and left handers, and how attentional and manual asymmetries develop and interact over developmental trajectories, may help clarify these relationships.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Tremelimumab is a selective human IgG2 mAb inhibitor of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) that has been combined with durvalumab in a Phase Ib study in patients with NSCLC (NCT02000947), with encouraging clinical activity and a manageable safety profile. While anti-PD-1/PD-L1 monotherapy may be associated with greater clinical benefit in patients with PD-L1+ tumors, combination therapy has clinical activity in both PD-L1+ and PD-L1– patients in several solid tumors, enhancing the antitumor activity of anti-PD-1/PD-L1 agents in patients with PD-L1– tumors. The PD-L1 and CTLA-4 pathways are non-redundant and preclinical data indicate targeting both may induce synergistic antitumor effects. Here we describe the CONDOR study (NCT02319044), a Phase II study to determine the efficacy and safety of durvalumab monotherapy, tremelimumab monotherapy, and their combination in PD-L1– R/M SCCHN patients who have failed prior platinumtherapy.First-line palliative treatment for patients with R/M SCCHN includes platinum-based chemotherapy. There are no standard second-line options upon relapse and median survival is limited. In SCCHN, tumors create a highly immunosuppressive environment and evade immune detection by exploiting inhibitory immune checkpoints such as the programmed cell death ligand-1 (PD-L1)/programmed cell death-1 (PD-1) axis, making immunotherapy an attractive option to study in this disease. Durvalumab (MEDI4736) is a selective, high affinity human IgG1 mAb that blocks PD-L1 binding to PD-1  will be randomized 1:1:2 to receive durvalumab (10 mg/kg IV) monotherapy; tremelimumab (10 mg/kg IV) monotherapy; or durvalumab (20 mg/kg IV) plus tremelimumab (1 mg/kg IV) combination therapy for up to 12 months (Figure This is a randomized, open-label, multicenter, global, Phase II study in immunotherapy-naïve patients with PD-L1ClinicalTrials.gov identifier NCT02319044.


Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 105 at a turn-on voltage as low as 0.5 V were recorded. Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous,  Here we show that zero dimensional (0D) heterojunctions between BNNTs and graphene could switch current flows.Graphene is known for its high electron mobility and zero energy gap nature146The graphene-BNNT heterojunctions are prepared by chemical vapor deposition (CVD)17I-V) measurements with the in situ SEM. 1, while another STM probe 2 was in contact with the graphene surface. The distance, d, between probe 1 and the vertical graphene-BNNT heterojunction, was controlled by changing the contact point on the BNNT.The as-grown graphene-BNNT heterojunctions were characterized for their electronic properties at room temperature by using a four-probe scanning tunneling microscopy (4-probe STM) system (see Methods)Vb  with a threshold turn–on voltage, Von ~0.5 V (inset). The current level detected at d = 0.10 μm is even higher, up to μA level (as limited by the preset 1 μA current limit), with Von ~0.15 V (inset). These conducting behaviors with obvious “on” and “off” states are different from the reported insulating nature of BNNTs185.For the case of d = 1.23 μm, we hardly detected any current flow across the graphene-BNNT heterojunction for a range of bias voltages, Vb  between I-V curves were measured . As shown in −7A is detected. We believe that the absence of the gating effect is due to the shielding of the metallic graphene located between the gate oxide surface and the heterojunction. As the junction is small in diameter (~60 nm) and is potentially surrounded by additional graphene layers underneath, an electrostatic screening effect will be able to effectively shield the gating effect. Therefore, gating the junction should still be possible if a top gate is applied.A full series of measured . The detTo understand these experimental observations, calculations were performed by employing Density Functional Theory (DFT)21I-V characteristics of pristine graphene and graphene-BNNT heterojunction are shown in I-V behavior for the pristine graphene is predicted affirming its metallic nature. On the other hand, the calculations predict very little, if any, electron transport through the graphene-BNNT heterojunction within a range of low bias voltages (i.e. ±0.1 V). At higher bias voltage, however, the linear I-V behavior is recovered with slightly higher resistance. The calculated switching properties of the heterojunction are in qualitative agreement with our experimental results.Next we calculated the electron transport properties of the heterojunctions using density functional theory together with the non-equilibrium Greens Function method see . Fig. 3dd = 0.10 μm, the effective dimension of the junctions is approximately ~120 nm in diameter.We believe that the switching behaviors observed here is due to the DOS mismatch at the heterojunctiond = 0.64 μm away from the heterojunction. Another STM probe is in electrical contact with the graphene sheet (beyond the SEM imaging window). As shown in Vb (“off” state) for both cases. At higher Vb, the heterojunction turned “on” with thresholds Von ~7 V and Von ~4 V for d = 0.73 μm and 0.64 μm, respectively. Obviously, Von for this horizontal heterojunction is higher than those discussed for a vertical heterojunction shown in Von. Such a DOS mismatch can only be artificially formed if local compression or severe bending occurs to the BNNT. It is unlikely to find such a deformation in as-grown BNNTs.We further examined the switching behavior of a horizontal graphene-BNNT heterojunction. In conclusion, we have demonstrated the fabrication of the stable graphene-BNNT heterojunctions without the use of catalyst. A bias-dependent switching behavior has been observed at the heterojunctions. DOS mismatch between graphene and BNNT at the nanoscale heterojunction is suggested to prevent current flow at low bias voltages, and turn on the current flow at higher applied bias. The novel Graphene-BNNT heterojunctions would likely combine the advantage of the ballistic nature of electron mobility°C in Argon ambient. These graphene sheets are then dispersed in tetrahydrofuran or isopropyl alcohol by sonication (10 minutes in a sonication bath). The suspended graphene was then coated on cleaned oxidized Si substrates and dried in hydrogen flow at 800 °C for 30 min. These graphene coated substrates are then used for the subsequence growth of BNNTs to form the heterojunctions. The growth of BNNT on graphene is based on our reported growth vapor trapping (GVT) chemical vapor deposition (CVD) method without the use of catalyst. These substrates were placed on the top of an alumina combustion boat in which B, MgO, and FeO precursors are loaded . This setup was placed inside a closed-end quartz tube in the horizontal tube furnace with the graphene sheets facing upward. The precursors and substrates were then heated up to 1100–1200 °C with an ammonia flow of 200–350 sccm and kept for 30 min. Images of as-grown graphene-BNNTs heterojunctions are shown in Fig. S1 and Raman spectra of these heterojunctions are shown in Fig. S2. We believe that the growth of BNNTs is initiated by point defects, where dangling bonds serve as the nucleation sites. As some of the point defects are not round, the initially grown BNNTs became distorted  were heat shocked into multi-layered graphene at 1000 How to cite this article: Parashar, V. et al. Switching Behaviors of Graphene-Boron Nitride Nanotube Heterojunctions. Sci. Rep.5, 12238; doi: 10.1038/srep12238 (2015).


In spoken interactions, interlocutors carefully plan, and time their utterances, minimizing gaps and overlaps between consecutive turns. Cross-linguistic comparison has indicated that spoken languages vary only minimally in terms of turn-timing, and language acquisition research has shown pre-linguistic vocal turn-taking in the first half year of life. These observations suggest that the turn-taking system may provide a fundamental basis for our linguistic capacities. The question remains, however, to what extent our capacity for rapid turn-taking is determined by modality constraints. The avoidance of overlapping turns could be motivated by the difficulty of hearing and speaking at the same time. If so, turn-taking in sign might show greater toleration for overlap. Alternatively, signed conversations may show a similar distribution of turn-timing as spoken languages, thus avoiding both gaps and overlaps. To address this question we look at turn-timing in question–answer sequences in spontaneous conversations of Sign Language of the Netherlands. The findings indicate that although there is considerable overlap in two or more signers’ articulators in conversation, when proper allowance is made for onset preparation, post-utterance retraction and the intentional holding of signs for response, turn-taking latencies in sign look remarkably like those reported for spoken language. This is consistent with the possibility that, at least with regard to responses to questions, speakers and signers follow similar time courses in planning and producing their utterances in on-going conversation. This suggests that turn-taking systems may well be a shared cognitive infrastructure underlying all modern human languages, both spoken and signed. Spontaneous conversations among speakers often run smoothly with slight overlaps and gaps between consecutive turns . ComparaOne of the substantial discoveries of the last 50 years is that sign languages show all the properties of full natural languages on all relevant levels of linguistic structure, including, for instance, sublexical structure at the phonological level . HoweverConversation analytic work on sign languages has been sparse, yet early studies of signed conversations have observed some remarkable features of signed interactions. terminal overlap  moving toward the position where a sign will be made as the other interactant is making a sign.” However, in considering the comparison between spoken and signed languages, we must bear in mind that the preparation for vocalization in spoken languages is mostly inaccessible to other participants, consisting apart from inbreaths in early motor preparation of the vocal organs  as the turn beginning as it most directly reflects the phonological content of a sign.In spoken conversation, addressees sometimes initiate a response at a possible point of completion while the initial speaker continues his turn, thus resulting in  overlap . Similarl organs . Therefol organs . In our Overlap at signed turn transitions may also result from turn-final holds, which are typically released as soon as the relevant response has been recognized . CrucialIf turn-taking lies deep in our communicational instincts as has been suggested , then itTo address this question we analyze turn-timing in 190 question–answer sequences captured from spontaneous conversations of Sign Language of the Netherlands Nederlandse Gebarentaal (NGT). Questions–answer sequences provide a particularly well-suited conversational context in which to investigate turn-timing, as questions make due a conditionally relevant and timely response cf. . The sigThe paper is structured as follows. Section “Materials and Methods” provides details on our data collection as well as the annotation scheme. Section “Results” presents a statistical comparison of turn-timing in the NGT sample to the spoken languages as reported by De structuur en ontwikkeling van conversaties in gebarentaal .This study exploits the NGT Interactive corpus, which consists of spontaneous conversations of native NGT signers in informal settings, which have been collected, and analyzed by Merel van Zuilen, Stephen C. Levinson and Connie de Vos (Max Planck Institute for Psycholinguistics), and Onno Crasborn (Radboud University) from early 2011 onward. All data and analyses have been ethically approved by the Radboud University Ethical committee under the research program The recording sessions of the NGT Interactive corpus took place in participants’ homes, at various deaf clubs, as well as a small restaurant, between participants who were long-term acquaintances and friends. These signers were also very familiar with the research assistant who recorded them, and who is a deaf native signer of NGT herself. The data therefore has the character of natural conversation. All conversations were recorded using two HD cameras from different camera angles. The data on which the present study is based features 16 signers  in one triadic and six dyadic interactions totaling 11 h and 2 min of raw video data. In one of the dyadic interactions, a third person occasionally joined the conversation, but did not participate in any of the question–answer sequences in our analysis. For this reason, this recording is treated as a dyadic interaction. All but one of the signers included in this study had acquired NGT early in life, before the age of ten and all three variants of NGT – Northern, Western, and Southern – are represented in the sample. Conversation topics ranged, unprompted by the investigators, from a work meeting regarding the write-up of a professional paper, home improvement activities, the history of the deaf club, and interpersonal relations.The video recordings were compressed into MPEG2 format at 1920 × 1080 resolution and 25 fps. The relevant sections were then translated into written Dutch and annotated further using ELAN video annotation software . As is cIn order to ensure a diverse sample of question–answer sequences, we selected 30 min segments from each video file that were dense in turn transitions. In identifying these sequences, we adopted the selection criteria which were originally developed as part of the MPI Coding Scheme for Question–Response Sequences in Conversation at the MPI for Psycholinguistics  and formhuh?). Similarly, in some contexts, polar questions evoked a minimal response such as a head nod (yes) or a side-to-side headshake (no). Importantly, sign languages are essentially multi-modal in nature in the sense that signers do not only use their hands but also their facial expressions and body postures to express meaning at the linguistic and paralinguistic level. The non-manual components are sometimes considered as the equivalent of intonation or prosody in sign . The stroke most directly represents the phonological form of a sign and includes the internal movement of a sign, in this case touching the contra-lateral upper arm . Subsequently to the stroke, a signer might hold a sign during interaction, for example to mobilize a response in their interlocutor . Finally, the sign may be retracted and the hands move into resting position .Our analysis of turn-timing is based on the coding of the various movement phases that make up a sign. Specifically, we adopted the movement phase coding developed for Sign Language of the Netherlands and co-speech gesture . This coImportantly, each sign is minimally associated with a single stroke, but the other three movement phases do not always occur . This anFor a subset of items (59 questions) a second coder, who is also a native signer of Sign Language of the Netherlands, applied the same Gesture Phase coding system. Subsequently, any items that showed discrepancies of more than two video frames were discussed, and adjusted when necessary. In a few cases these differences were based in a distinct phonological analysis of the signs that were being used and these two interpretations could not be reconciled. After these discussion sessions the overall correlations between these two coders was 0.9 for the sign-naive boundary measures and 0.98 for the stroke-to-stroke boundary measures.Figure 2 illustrates each of the reported phonetic measures schematically. In section “Results,” each of these phonetic measures of signed turn-timing are compared to findings from the spoken turn-timing in cross-linguistic study presented by In our study we report on three phonetic measures of turn transition times based on the coding of gesture phases. The first measure looks at sign-naive turn-boundaries and includes all manual actions, that is, all movement phases that make up a signer’s utterance. The second measure looks at stroke-to-stroke turn boundaries, which run from the start of the initial stroke of a turn till the end of the turn-final stroke. For each signer, gestural movement phases from both hands were taken into account. The third and final measure calculates the offset of the addressee’s preparation phase with respect to the end of the question’s final stroke, and is called signed utterance launch. Figure 3 displays an excerpt from the corpus to exemplify the three phonetic measures. This question–answer sequence stems from a conversation between two males who are close friends living in the North of the Netherlands. They are discussing remodeling activities while enjoying lunch on a roof top terrace. Directly preceding the excerpt, the signer to the viewer’s right (R) indicates his misunderstanding using a minimal repair initiator by furrowing his brows and leaning forward similar to a spoken ‘huh?’ (cf. hier), which is formed by a downward index finger point, and co-produced with the Dutch mouth movement nu ‘now.’ At the end of his question, the sign HERE is immediately retracted over 430 ms without a sentence-final hold, presumably because the addressee (signer R) has already raised his hand to produce an appropriate response. Signer R’s answer starts off with the sign NOW, and he initiates the preparation of this initial sign before signer L has initiated the start of the preparation of his final sign. As a result, both signers overlap by 690 ms according to the sign-naive turn boundary measure and the launch of R’s sentence articulation has a negative value of -260 ms. According to the stroke-to-stroke measurement, however, there is a slight gap of 30 ms between both turns. This turn transition is detailed in  which displays snapshots from both camera angels of the final frame of Signer L’s turn-final stroke. On the left-hand side there is a clear view of signer L and the end state of the sign HERE. The camera view on the right-hand side clearly shows signer R who is in the middle of the preparation phase of his turn-initial NOW; the white arrow indicates the trajectory of its stroke. The exact timing of this turn transition is illustrated by a scaled representation of the gestural movements of this turn transition in Figure 3B.uh?’ cf. . As explFigure 4A shows a density plot of turn transition offset for the overall data set according to the sign-naive turn boundary measure. The sign-naive boundary measure calculates turn-timing by including all gestural movement phases of the hands. According to this phonetic measure, the average offset of answers to questions was -812 ms, the median was -607 ms, and the mode  was -361 ms. These negative values of central tendency indicate that addressees generally start signing well before the question has fully ended. The average value of -687 ms was 6.18 SDs below the cross-linguistic average turn transition time as estimated from m = 229 ms, SD = 168 ms). Assuming that average turn transition times across spoken languages are normally distributed, and using the data reported in p < 0.0001). The sign-naive turn boundary measure thus suggests that the timing of responses to questions in the visual modality deviates substantially from oral-auditory turn-taking in that it exhibits both more and more extended overlap.To test whether signers optimize turn-taking on the basis of stroke-to-stroke turn boundaries, we compared turn transition times in NGT with turn transition times in spoken question–answer sequences in ten languages as reported in Figure 4B shows a density plot of the stroke-to-stroke turn boundary measure. According to this measure, turn transition times in NGT now exhibit a positive gap, with an average of 307 ms, a median of 269 ms, and an estimated mode of 227 ms. The average value of 307 ms was only 0.46 SD above the cross-linguistic average turn transition time as estimated from p = 0.32). When we exclude utterance-initial preparatory movements, and utterance-final holds and decays, turn-timing in signed interaction thus falls within range of oral-auditory turn-taking as reported by Figure 5, which shows the average turn transition times in Secondly, we calculated turn-timing following the stroke-to-stroke boundary measure, which is based on the hypothesis that signers observe stroke-to-stroke turn boundaries. This phonetic measure calculates the offset of the answerer’s initial stroke with respect to the end of the final stroke of the questioner. Another way of looking at signed versus spoken turn-timing is by comparing the distributions of overlapping and delayed turn transitions. Figure 6 presents an overview of the percentages of overlapping answers to questions, including the data reported in this study. As estimated by p = 0.28). According to the sign-naive measure, however, 82.2% of answers overlap with the respective question. This percentage clearly falls outside the cross-linguistic range for spoken languages. The probability of observing this value or a higher value in the cross-linguistic distribution is extremely low (p < 0.00001).Figure 7 presents an overview of the percentages of transitions between answers and questions involving a gap of more than 120 ms, including the data reported in this study. As estimated by p = 0.54). According to the sign-naive measure, however, only 17.8% of answers overlap with the respective question, which would be three times less than the spoken language which allows for the smallest number of delays in question–answer sequences. The probability of observing this value or a lower value in the cross-linguistic distribution is much lower (p < 0.00001).Table 1 summarizes all main results from the present corpus analysis.Unlike spoken languages, signed languages offer us the unique opportunity to examine turn preparation using non-invasive methods. In our data, the preparatory phase of utterances had an average duration of 474 ms, a median of 280 ms, and an estimated mode of 255 ms. We computed a third turn transition timing measure corresponding to the latency between the end of the final stroke of the question and the onset of the initial preparatory movements of answer articulation. Relative to the end of the final stroke of the question, response articulation in our data starts with an average latency of -86 ms, a median latency of -78 ms and a modal latency of -53 ms. The timing of preparatory movements in sign is thus slightly earlier than the initiation of pre-utterance inbreaths in answers to questions in spoken Dutch 15 ms; . We retup > 0.1 in all three cases), indicating that the triadic conversation was not significantly different from the dyadic conversations in terms of turn-timing.As explained in Section “The NGT Interactive Corpus,” one of the recordings in our corpus consisted of a triadic interaction, the other six involving dyadic conversations. Because turn-timing might differ between triadic and dyadic interactions , we examined each of the timing measures presented in the previous subsections  as a function of the number of participants in the interaction. We fitted a series of mixed-effects regression models with each of the timing measures as the response, number of participants (dyadic vs. triadic) as a fixed factor, and conversation as a random factor. None of the three models yielded a statistical effect for the fixed factor number of participants  in order to address the question as to what degree turn-timing in signed conversation differs from turn-timing in spoken conversation. The present study has focused on responses to questions, as questions require a timely and contingently relevant response, and could therefore serve as a baseline measure as to how much overlap or gap might be allowed in a given language. Moreover, the timing of responses to questions has been documented in a wide range of spoken languages , thus alAs noted in the introduction, it has previously been claimed that signed conversation exhibits more overlap than spoken conversation. We have also seen that, using the stroke-to-stroke measures, the proportions of turn transitions with noticeable gaps and overlaps in NGT is within the same range as spoken languages according to the stroke-to-stroke boundary measure. These comparisons were carried out on the assumption that the threshold for noticeable gaps and overlaps lies at FTOs of 120 ms and -120 ms, respectively cf. . At presFigure 8 shows a schematic representation of typical time courses in a signed question–answer sequence based on modal values in our data , and, for the sake of comparison, and as reported by Figure 8B), and in a sequence in which a preparatory inbreath was produced . Notice that, in spoken answers too, in line with our findings for sign language, the typical onset of the physical response, in the form of a preparatory inbreath, or of speech proper in answers not preceded by an inbreath, typically starts briefly after the end of the question.In sign, the articulators are large and heavy, and reaching the articulatory targets of hand strokes from an inactive state will require more time than a vocal articulatory gesture. For this reason, the timing of preparatory hand movements preceding signed turns-at-talk may provide a crucial insight into the time course of signed utterance planning. In our question–answer sequences, we have observed that initial preparatory hand movements of responses are typically launched during the second half of the last stroke of the question, and that the preparatory phase typically ends a couple of 100 ms after the last stroke of the question. On a par with the findings of The time course of turn production critically depends on the perception and comprehension of the preceding turn . Recent A related issue concerns the types of non-manual signals that might enable the accurate projection of TRPs by sign-perceivers. Reaction time experiments are currently being run to establish sign-perceivers’ sensitivity to TRPs as defined by stroke-to-stroke turn boundaries . That study also aims to identify the visual information signers rely on to determine utterance boundaries online, on the basis of linguistic annotations of the visible cues in this additional data set. On a par with previous work on spoken languages , we hypoThis paper has centered on question–answer sequences within a relatively limited data set. Our findings are in accordance with the hypothesis that there may be a single turn-taking system underlying both signed and spoken interactions . If thisIn sum, the observed patterns in signed turn-timing in NGT are within the range observed for spoken languages in terms of response latency to questions once we exclude preparatory movements from turn beginnings and retraction phases from turn ends. Moreover, unlike previously argued by The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Gypsies, Travellers and Roma (referred to here as Travellers) experience significantly poorer health and have shorter life expectancy than the general population. They are also less likely to access health services including immunisation. To improve immunisation rates, we need to understand what helps and hinders individuals in these communities in taking up immunisations. This study has two aims: (1) Investigate the barriers and facilitators to acceptability and uptake of immunisations among six Traveller communities in the UK; (2) Identify potential interventions to increase uptake in these Traveller communities.A three-phase qualitative study with six Traveller communities. PHASE 1: In each community, we will explore up to 45 Travellers’ views about the influences on their immunisation behaviours and ideas for improving uptake in their community. PHASE 2: In each community, we will investigate 6–8 service providers’ perspectives on barriers and facilitators to childhood and adult immunisations for Traveller communities with whom they work, and ideas to improve uptake. Interview data will be analysed using the Framework approach. PHASE 3: The findings will be discussed and interventions prioritised in six workshops, each with 10–12 phase 1 and 3–4 phase 2 participants.This research received approval from NRES Committee Yorkshire and The Humber-Leeds East (Ref. 13/YH/02). It will produce (1) findings on the barriers and facilitators to uptake of immunisations in six Traveller communities; (2) a prioritised list of potentially feasible and acceptable interventions for increasing uptake in these communities; and (3) methodological development in undertaking research with diverse Traveller communities. The study has the potential to inform new ways of delivering services to ensure high immunisation uptake. Findings will be disseminated to participants, relevant UK organisations with responsibility for the implementation of immunisation policy and Traveller health/welfare; and submitted for publication in academic journals.ISRCTN20019630. This is the first large-scale multi-community qualitative study exploring barriers and facilitators to childhood and adult immunisation for Travellers in the UK.The findings will have the potential to inform new ways of delivering accessible immunisation services to socially excluded, marginalised communities.Our research team may be perceived as ‘outsiders’, resulting in difficulties in engaging with Travellers to participate.Note. Throughout this paper, we use the term Traveller in its broadest sense to include distinct and diverse Gypsy, Traveller and Roma communities, who may be settled or nomadic, and may live on authorised or unauthorised sites or in houses). Despite a greater health need, there is low uptake of health services by Travellers, including preventive healthcare.7Travellers typically experience significantly poorer health and shorter life expectancy compared to the general population.The public health benefits and cost-effectiveness of immunisation are well established.19A large body of literature27Many of the issues identified in this literature are likely to be similar for Travellers. However to develop interventions that are tailored to the needs of diverse Traveller communities, further research with these communities is required. To date, a small number of studiesThe effectiveness of interventions to increase immunisation uptake among childrenInvestigate the barriers and facilitators to acceptability and uptake of immunisations among six Traveller communities  across four UK cities;Identify possible interventions to increase uptake of immunisations in these Traveller communities, which could be tested in a subsequent feasibility study.Investigate the views of Travellers on the barriers and facilitators to acceptability and uptake of immunisations and explore their ideas for improving immunisation uptake;Examine whether and how these responses vary across and within communities, and for different vaccines (childhood and adult);Investigate the views of service providers on the barriers and facilitators to uptake of immunisations within the Traveller communities with whom they work, and explore their ideas for improving immunisation uptake;Examine whether and how these responses vary within and across communities, for different vaccines (childhood and adult) and for different service provider roles;Use the data collected from (1 to 4) to identify possible interventions to increase uptake of immunisations in the six Traveller communities;Conduct Feedback Workshops in each community to discuss findings and to produce a prioritised list of potentially feasible and acceptable interventions to be considered for testing in a subsequent feasibility study.This three-phase qualitative study is the first ‘intervention development’ stage of the Medical Research Council Framework for developing and evaluating complex interventions.43The study will focus on six Traveller communities and be undertaken in four UK cities  and human papilloma virus (HPV) vaccine (given at 12–13 years); and adults who are pregnant, over 65 years or have long-term conditions for views on flu and pertussis vaccines). Typically, decisions on childhood immunisation are made by mothers;within a community across gender and age as well as draw out meaningful comparisons across Traveller communities, to allow robust conclusions to be made.Phase 2: Service providers in the four cities will be recruited to the study. We will purposively sample to ensure that we interview a mix of ‘frontline workers’  and those working in more strategic/commissioning roles . We will aim to interview six to eight service providers in each city . Examples of organisations and providers that we intend to approach are presented in Phase 3: A subsample of participants from phases 1 and 2 will be invited to take part in the ‘Feedback Workshops’, specifically between 10 and 12 Traveller participants per community and three to four service providers . Ideally, we will attract a mix of Traveller men and women, across ages (including teenage girls) with different experiences of immunisations; and a mix of frontline service providers and those with a more strategic role.This is a complex, multisite project working with socially excluded, marginalised communities who are traditionally hard to engage in research.47Phase 1: In each community, we will use a multipronged approach to access and recruitment. We are aware that our position of researchers as ‘outsiders’ with few similarities of experience and no ‘network connections’ with participant Traveller communities could result in difficulties in gaining access.49The study will be discussed with members of the community and written information provided for people to read or have read to them by others to aid discussions with family members and peers. For the two European Roma communities, information will be in English and Romanian/Slovakian. We will return a week later to establish who might wish to take part, and to arrange a time and place for the interview. We will regularly meet with the community during the recruitment phase.Phase 2: In each city, we will establish a list of contacts of the relevant service providers. We will approach these people by email, in the first instance, with a participant information sheet (PIS) and then follow this up with a telephone call a week later. Our existing links to the multiple agencies working in each city will also be used to facilitate introductions.Phase 3: Participants in phases 1 and 2 who agree to be contacted about phase 3 will be reapproached using their preferred method of contact and provided with a PIS about the Feedback Workshop. Where insufficient phase 1 participants are able to attend, we will seek to recruit new members of the community to attend the workshop.Phase 1: We will conduct small group interviews with members of the same family to elicit a cross-generational/lifespan perspective. We also plan to run group interviews with teenage girls, and with young women planning families, pregnant women and those with preschool children, to capture peer influence on immunisation decisions. While immunisation may not seem a particularly sensitive issue (with the exception of HPV), group interviews may not be appropriate or favoured. We will, therefore be flexible about whom and how many participants take part in an interview. Individual and group interviews will be conducted face to face in participants’ choice of setting. With the consent of participants, interviews will be recorded digitally and transcribed verbatim. Interpreters will be employed for Roma interviews.Phase 2: We will conduct individual interviews with the service providers face to face in participants’ choice of setting. With their consent, interviews will be recorded digitally and transcribed verbatim.In phases 1 and 2, we will use topic guides for the interviews to ensure consistency; however, the format will be flexible to allow participants to generate naturalistic data on topics they view as important. We will explicitly pursue negative cases (‘elements in the data that appear to contradict the emerging view’) ref. , p. 51 tAt the end of phases 1 and 2, for each of the six Traveller communities, we will (1) understand the potential barriers and facilitators for take-up of immunisations  and (2) have ideas for the content and delivery of potentially feasible and acceptable interventions to increase immunisation uptake for all five levels of the SEM. We will have insight into whether the barriers and facilitators and interventions are similar or different dependent on the gender, age and self-reported immunisation history of Traveller participants, the professional role of service providers and across different vaccines (childhood/adult). These outputs will be presented at the Feedback Workshops in Phase 3.Phase 3: A Feedback Workshop will be held locally for each Traveller community. The aim of the workshops is to disseminate the findings of phases 1 and 2 and to discuss and ‘co-produce’Phases 1 and 2: Interviews will be fully transcribed and data subjected to thematic analysis using the Framework approach,53Familiarisation—The interview transcripts will be read and emerging ideas and recurrent themes recorded.Identifying a thematic framework—A thematic framework will be set up in which the interview data will be organised. This will be informed by the SEM. Additional themes representing emerging issues from the data will be added. The framework will be applied to three to four transcripts to refine. The same thematic framework will be used to analyse the data for all the six Traveller communities and associated service providers.Indexing—The thematic framework will be systematically applied to the interview data.Charting—Charts will be drawn up for each theme and summaries of responses from participants (and verbatim quotes) entered. This will enable us to consider the range of views within each theme, that is, on (1) barriers, (2) facilitators to immunisation, (3) ideas for intervention across the five levels of the SEM; and (4) other emerging issues.Mapping and interpretation—The charts will be reviewed and interrogated to compare and contrast views, as well as to seek patterns, connections and explanations within the data.The five stages of analysis, specified below, will first be undertaken independently for each of the six Traveller communities and for both phase 1 and phase 2 data. This ‘within-community’ analysis will be led by CJ, LD and CE. Members of the research team based in each city will contribute at stages 2 and 5. This will enhance rigour and ensure that the local context in which the data are collected and where participants live is appropriately considered. NVivo software will facilitate data management.The final outputs of the analysis of phase 1 and 2 data will be a thematic synthesis that takes account of the inferences derived from all the interview data for the sample as a whole.This research has received approval from NRES Committee Yorkshire and The Humber—Leeds East Ref. 13/YH/02). Drawing on the British Psychological Society's Code of Human Research Ethics,3/YH/02. Comprehensive, in-depth findings on the barriers and facilitators to uptake and acceptability of childhood/adult immunisation both within and across six Traveller communities living in four cities across England and Scotland.A prioritised list of potentially feasible and acceptable interventions for increasing immunisation uptake across the five levels of the SEM for these Traveller communities.Methodological development in undertaking research with diverse Traveller communities living in different localities. Historically, research has been small scale, localised and with one community. Lessons learnt from this large-scale multi-city qualitative study can be used to improve the quality of future research in Traveller communities of a similar scale.There will be three key outputs:The findings will be published within the final report to the National Institute for Health Research Health Technology Assessment (NIHR HTA) programme. A local summary will be disseminated to the community and local organisations with whom we have worked to access/recruit Traveller participants to the study and to service providers in that locality who took part. A summary of the findings on the barriers and facilitators to uptake and acceptability of immunisation for all six Traveller communities will be sent to relevant national UK agencies and organisations responsible for the implementation of immunisation policy and Traveller health and welfare including professional bodies. We will also submit research papers to relevant professional journals and conferences. Academic papers will be submitted for publication in high-impact peer-reviewed journals.


Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered—exclusively—by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided. Nakaya demonstrated that snow crystals grow in cold humid air as a large variety of mainly plane crystals depending on both temperature and humidity of air 80 years ago  specifically design to control both temperature from −13.0 ± 0.1 up to 30.0 ± 0.1 °C and humidity from 5 ± 1 to 99 ± 1 %. A schematic of the experimental layout is shown in Fig. In all cases freezing is triggered at the certain point as shown in Fig. In all cases freezing is always nucleated at the surface. Plane single crystals are nucleated and grow on the very surface of the liquid supercooled water. Figures Figure As it can be seen in the figures and videos above, surface crystals frontline growth velocity strongly depends on temperature (and corresponding humidity as shown in Fig. The experiments described in the present paper demonstrate that the dependence of the freezing point of deionized water on humidity in air is intrinsic to the existence of the liquid water–air interface. The freezing temperature-humidity curves for open containers and for droplets are the same. For a given temperature, surface freezing is nucleated at the liquid water–air interface by a high enough humidity, forming a surface ice crystal prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. An evidence of simultaneous nucleation of Surface ice single crystals is also provided.