Beginning with graphene on untreated thermal oxidised silicon, a minimum conductivity (σmin) occurring at gate voltage Vg = 15 V (Dirac Point) is measured. It was found that more aggressive treatments (O2 plasma and UV Ozone treatments) further increase the gate voltage of the Dirac point up to 65 V, corresponding to a significant increase of the level of p-doping displayed in the graphene. An electrowetting model describing the measured relationship between the contact angle (θ) of a water droplet applied to the treated substrate/graphene surface and an effective gate voltage from a surface charge density is proposed to describe biasing of Vg at σmin and was found to fit the measurements with multiplication of a correction factor, allowing effective non-destructive approximation of substrate added charge carrier density using contact angle measurements.Correlations between the level of p-doping exhibited in large area chemical vapour deposition (CVD) graphene field effect transistor structures (gFETs) and residual charges created by a variety of surface treatments to the silicon dioxide (SiO Since its discovery in 2004 by A. K. Geim and K. Novoselov3σmin) which resides at zero applied gate voltage (Vg = 0). However, real world devices almost always have an intrinsic hole concentration, biasing Vg at the Dirac point to a finite positive value. It is well known that the carrier concentration in graphene is strongly affected by adsorbates in contact with graphene and this is considered to be the most likely cause of the intrinsic carrier density bias. For brevity Vg at σmin is referred to as VD from here onwards.The ability to locally modulate the charge carrier density of graphene has enabled the creation of gFET devices. Theoretically the ambipolar field effect in gFETs exhibits a symmetric drain-source current voltage characteristic (I–V curve) about the Dirac point  of a water droplet placed on the graphene and the bare substrate of each treated gFET device. This finding quantifies substrate treatment as a subtle and often overlooked source of doping in graphene. We understandably go on to report on a correlation between θ and VD in graphene and present an accompanying electrowetting model in the hope of developing a facile technique for quick estimation of the p-doping level.In this study we investigate how typical SiO−3 mbar) which allows the growth of high quality (≈95% single layer) graphene as shown in 52 prepared by thermal oxidation. The CVD graphene has respectable transport properties post-transfer as confirmed by Raman spectroscopy and electrical characterisation measurements presented in CVD graphene is synthesized by use of a vertically arranged vacuum reactor  sonication (40 minutes)Acetone and Isopropanol sonicated (20 minutes acetone sonication followed by 20 minutes IPA sonication)λ = 253.7 nm)UV-Ozone treated (30 minutes using mercury lamp in atmospheric lab conditions. UV energy ≈647 kJ/mol assuming Oxygen plasma (−500 V bias at 100 W for 5 minutes)Five different graphene-substrate interfaces were prepared by SiOThese treatment methods were chosen due to their common use in graphene substrate treatment with the purpose of substrate cleaning.μm thick) is used as a back gate and is contacted in a similar way. The 90 nm thick SiO2 layer acts as a gate dielectric. A schematic of the gFET fabrication and set-up is depicted in Keithley 2636B sourcemeter in ambient lab conditions.Ohmic contacts are coupled to the conducting channel and the gate electrode to measure the DC electrical properties of the graphene. The gFET source and drain electrodes are constructed by contacting the sample with silver paint. Channel lengths and widths are 3 mm each and equal for all samples being measured. Boron-doped Si  on the gFET channels using a Dataphysics OCA-15 goniometer. Contact angle measurements were also made on the bare treated substrate which the graphene did not cover.Following the gFET electrical characterisation, contact angle measurements were made using de-ionised HD and θ which is portrayed in et al.et al.2, with an increased contact angle of ≈15°. A similar result was also seen in samples with no-treatment but to a lesser extent with an average contact angle difference of ≈5°. No treatment and water sonication are the most gentle processes and are thought to alter the SiO2 surface by the smallest amount while more aggressive treatments alter the surface to a greater extent and it is possible that this masks any hydrophobic effects from the graphene.We measured a negative correlation between V2 plasma are expected to partially etch the surface of the substrate, roughening it as well as cleaning it. With roughening of SiO2 it may be expected that hydrophobicity increases due to a surface water droplet tending towards Wenzel and Cassie Baxter states2 samples post transfer are More aggressive treatments such as Oθ and VD there is evidence that it is a treatment induced surface adcharge density that acts as the source of doping in the graphene. With more aggressive substrate treatment it can be assumed that a greater surface adcharge density is induced, causing the measured positive shift in VD (p-doping increase) and surface hydrophobicity decrease. The doping effect can be attributed to charge carrier acceptor/donor effects of adcharges trapped in the interface of the graphene and substrate. Work by Nistor et al.2 defects can act as a reservoir for graphene’s charge carriers. Most defects will not have a doping effect on graphene and tend to self-passivate over short time scales or annealing. However, oxygen rich open-shell/dangling bond defects strongly p-dope graphene with Dirac point shifts of +0.9 eV from the Fermi level, contributing up to 9.6 ⋅ 1013 cm−2 P-type carriers. There is no N-type equivalent defect with this degree of doping from SiO2, this is a likely cause why graphene on SiO2 is most frequently measured with a hole carrier bias as originally found by Novoselov et al.1213142 defects and surface admolecules, water has been hypothesised to have a profound p-doping effect on graphene and carbon thin films16172-graphene interface has a volume proportional to the surface hydrophobicity and adcharge density.With the measured correlation between D = 15.6 V, suggesting that there is an inherent adcharge density/effective electric field in standard commercially bought SiO2/Si wafers which induces p-type carriers. There have been many publications researching the effect of adsorbates on the graphene surface, typically hydrocarbonsD and θ measurements were not made immediately after fabrication in this study so as to represent a typical graphene device. On account our measurements may have higher θ and VD values due to ambient hydrocarbon adsorption.Without treatment Vθ and the positive shift of VD caused by adcharges. It can be assumed that adcharges, with a cumulative bias towards either positive or negative charge have a surface charge density (Qsl) which will shift the point of minimum conductivity away from VD = 0 of ideal graphene by inducing p- or n-type charge carriers and reduce θ respectively. Note that Qsl is equivalent to the charge carrier density induced in graphene (n/A).Building from literature on the electrowetting of dielectrics2021D is an effective applied static field inherent in the system caused by Qsl and will be superposed with an applied Vg creating a total effective applied voltage Veff = Vg − VD. At Veff = 0 the Fermi level of graphene will be at its most resistive state, the Dirac point. Veff is a measure of the total doping in graphene. With the effective static field caused by −VD there is a proportional inherent static capacitance between the back gate and adcharges. Generalising the set-up to a Lippmann’s capacitive electrowetting modelθ and −VD. With the addition of Qsl to the substrate surface an effective reduction in interfacial tension between the liquid and substrate surface 2 dielectric capacitor. The thickness of the added interfacial capacitor is typically negligible in comparison to the dielectric and consequently s ≈ Cdielectric.Using a first principles approach it can be assumed that −Vγsl is a charge independent tension between sample and liquid which is equal to eff independent relationship between θ and γsl can be defined using Young’s Equilibrium Contact Angle formula21Where θpzc is the non field biased contact angle of the substrate/sample  and is a measure of θ at Veff = 0. γij is a measure of tension between respective sample-atmosphere (sv), sample-liquid (sl) and liquid-atmosphere (lv) interfaces. The Veff dependent θ can be determined by replacing γsl with where cos Rearranging for the effective applied total voltage gives:Finally an induced charge carrier density can be described using FET electrostatics:θ measurements at Vg = 0 or total doping when Vg ≠ 0 if −VD has already been determined by VD measurement.γlv = 72.5 ⋅ 10−3 N/m, x = 90 nm. Interpolating data from θpzc = 97.5°, it is assumed θpzc is constant with treatment as the sample is always graphene/SiO2. This gives a model fit to our experiment in the form of eff = 0. Negative and positive charge carrier density concentration indicates hole and electron doping respectively.The proposed model can be correlated to our set up using experiment values θ > θpzc then Veff will become an imaginary value. These values hold no significance and the model in θpzc and θ = 0. θpzc is the most hydrophobic state that the model predicts for the graphene/SiO2 . For treatments that create a more hydrophobic surface such as HMDS treatment, the value of θpzc in γij values.Where D. θ measurements are made at Vg = 0 and therefore the total effective field acting on the contact angle droplet during the measurements is Veff = −VD. The empirical data from β = 3.75 a statistically significant fit is produced with the data, shown as a burgundy trace in The treated gFETs are proposed to have an inherent applied static gate voltage, −Veff values can be attributed to the need for a co-efficient which incorporates effects from spontaneous charge adsorption from the contact angle liquid. Spontaneous charge adsorption occurs at first contact of the droplet to the sample surface. Intuitively this will contribute to the existing adcharge density and superpose with the existing surface charge. It is expected that this will reduce the surface charge magnitude as polar molecules of opposite polarity to the sample surface will be deposited/adsorbed to the surface, reducing the value of |Veff|, with the amount of reduction proportional to the existing Qsl. As VD measurements were made without a contact angle liquid in the empirical data presented in eff| reduction and hence a greater |Veff| value is expected compared to measurements with a contact droplet.The models lower Veff can determine if spontaneous charge adsorption is a viable β mechanism. Using the approximation With surface charge adsorption there will be an expected reduction in polar solutes in the liquid on its application to the surface. Consequently there will be a relative change in its pH. Forming a relationship between ΔpH and Vγsl)Gibbs adsorption isotherm can be used to derive a relationship between modified interfacial tension between the substrate and droplet liquid (mol/m2), X± is the activity of the charging particle/molecule, R is the ideal gas constant, T is temperature and pH is the measure of droplet acidity. Depending upon the polarity of X, the sign of OH− and H+ are the most probable charging sources as H2O is the contact solution. From d(pH) ∝ γlv ⋅ d cos θ. Therefore with a change in pH of the droplet liquid due to spontaneous charge adsorption we can expect a modification of Veff due to shifts in cos θ, cos θpzc and γlv away from the modelled value. This indicates a viable reason for the difference in modelled and empirical data and also shows viable measurement mechanism for β other than Veff measurement.where β can be dubbed a spontaneous surface adsorption constant and it is expected that for H2O β < 3.75. Whereas for less polar liquids/gases is it expected β → 3.75 until the atmospheric limit. Veff consequently can be modified to include a term for the reduction in the surface charge from spontaneous charge adsorption, which is a function of all other effective applied voltages, Vl = Vl(Vg − VD). The model can hence be modified to include spontaneous charge adsorption:The correction factor β hypothesis a gate voltage of 0 → −40 V was applied to the H2O sonicated gFET devices while simultaneously measuring the contact angle of a H2O droplet on the graphene surface. The negative Vg applied acts to further bias graphene with hole charge carriers. −VD was measured at −17.88 V without a droplet on the graphene surface, indicating the existing hole bias from the surface charges. With a droplet added to the graphene −VD was measured at −5.71 V, therefore Vl = 12.17 V and corresponds to β = 3.13, 16% away from the expected 3.75.Testing the model and g is applied to the droplet on graphene set-up a shift in Veff occurs from −5.71 V → −45.71 V with a respective change in θ from 89°–25°. The green trace in θ ≤ 25°. By asymptote matching the fit to the model it has a β ≈ 0.91, supporting the hypothesis that β decreases with droplet/contact environment polarity. The saturation point in θ occurs where any further applied voltage does not further wet the surface, θpzc from 97.5° to an interpolated value of 95.8°. The time frame between measurements shows graphene to be predominantly chemically unchanging under atmospheric conditions and indicates the ability of graphene to be integrated into re-usable, long term commercial devices.When Veff = −VD, can be approximately determined from contact angle measurements in atmospheric conditions (before droplet contact and after droplet evaporation) using β ≈ 3.75 for a similar set-up.With the data presented it is proposed that the inherent doping of a gFET, V2 and that treatments designed to remove organic debris from the substrate of graphene based devices increases the hole concentration. We present a correlation between the contact angle of graphene and the level of p-doping, confirming that it is a surface charge density induced from substrate treatment that alters graphene’s transport properties. We developed an electrowetting model that shows the contact angle of a water droplet on a SiO2/Si substrate can be used as an indicator for the level of p-doping to be expected in graphene being transferred onto a given substrate. We applied our experimental set-up and data to this model and found a fit with the application of a spontaneous adsorption constant. We went on to validate the model experimentally by applying a gate voltage to a water droplet on the surface and measuring changes in its contact angle. Thus giving promise for a quick and non-destructive method for optimising substrate treatment and approximating the electrical properties of graphene by measuring the contact angle of a liquid droplet.We show that graphene is inherently p-doped on untreated SiO−3 mbar. 25 μm thick Cu foil is used as the growth substrate/catalyst and CH4 as the carbon source. The Cu is annealed at 1000 °C for 60 minutes in the quartz furnace chamber prior to CVD. Growth temperatures of 1035 °C were used with H2 and CH4 flows of 80sccm and 1sccmn respectively at a pressure of 110 mbar during graphene growth. Growth time was limited to >5 minutes.CVD was used to grow graphene using a hot walled furnace with a base pressure of 104)2S2O8) solution (1 g/100 ml). Three etchant exposures are used for a maximum of 12 hours each. The remaining PMMA/graphene stack is then floated on two consecutive ultra-pure water (18.2 MΩ cm @ 25 °C) baths to rinse the graphene surface for up to 6 hours per bath. The sample is manoeuvred between solutions using a ladle. Consequently fresh solutions are partly contaminated with the previous solution, hence the need for several baths. The sample is pressed against/scooped using the target substrate, allowing the graphene/PMMA to adhere to the surface (graphene in contact with the substrate) and allowed to dry for 24 hours under laboratory ambient conditions. Dichloromethane is used to etch the PMMA from the structures for up to 24 hours. The Dichloromethane is delicately stirred using a magnetic stirrer. The sample is then removed from the etchant and the solvent softly blown off the surface with a nitrogen gun.Liquid PMMA (A6) is syringed onto the CVD graphene/Cu stack and spun at 8000RPM for 60 seconds leaving a PMMA layer of thickness <400 nm. The PMMA is cured in ambient conditions for 24 hours. The bottom side of Cu is treated with a 10% nitric acid solution for 60 seconds and brushed with a cotton bud hence removing unwanted graphene growth on the Cu foil. The Cu is etched with an ammonium peroxidisulphate ((NHg of 0 to 70 V is applied (500 points per scan and each point scan measured for 50 ms). The source-drain current (ISD) is measured at each Vg at a constant source-drain voltage (VSD) of 200 mV and consequently the resistance can be determined of the channel. It is important to note that gate-source current (IGS) is also measured at each point to ensure measurements are not biased by any form of leakage through silicon dioxide dielectric gate layer.A two-channel Keithley 2636B sourcemeter is employed to carry out the field effect characterisations. The unit has the capability of supplying voltages up to 200 V from a single channel. For each gFET device, Vμl syringe. Each droplet was of volume 22 μl ± 1 μl. The water droplet is immediately illuminated from one side with a diffuse light source and the contour of the droplet is profiled from the opposing side. The contact angle was determined for each droplet using Tangent Leaning fitting at the three phase point. This method was identical for measurements made on the graphene surface as the bare treated substrate surface.Contact angle measurements are made using the Sessile drop method. Water droplets were deposited using a Hamilton 500 How to cite this article: Goniszewski, S. et al. Correlation of p-doping in CVD Graphene with Substrate Surface Charges. Sci. Rep.6, 22858; doi: 10.1038/srep22858 (2016).


Since its discovery, the wetting transparency of graphene, the transmission of the substrate wetting property over graphene coating, has gained significant attention due to its versatility for potential applications. Yet, there have been debates on the interpretation and validity of the wetting transparency. Here, we present a theory taking two previously disregarded factors into account and elucidate the origin of the partial wetting transparency. We show that the liquid bulk modulus is crucial to accurately calculate the van der Waals interactions between the liquid and the surface, and that various wetting states on rough surfaces must be considered to understand a wide range of contact angle measurements that cannot be fitted with a theory considering the flat surface. In addition, we reveal that the wetting characteristic of the substrate almost vanishes when covered by any coating as thick as graphene double layers. Our findings reveal a more complete picture of the wetting transparency of graphene as well as other atomically thin coatings, and can be applied to study various surface engineering problems requiring wettability-tuning. The graphene wetting transparency was spotlighted because of its versatile potential applications789et al.Graphene has been a subject of intense research on the basis of its superior optical transparency, electrical conductivity, and mechanical strength12345et al.Although Shih In this work, we report a unifying framework to account for the bulk modulus of the liquid as well as the surface roughness to realistically describe the wetting phenomena. First, we correct a few mathematical mistakes of the previous work in calculating the van der Waals (vdW) interaction energy between the liquid and the substrate. With the corrections, the previous theory predicts zero contact angle for any hydrophilic solid covered by graphene, i.e. complete breakdown of wetting transparency. By adjusting the contact distance between substrate and liquid, the theory can fit experimental data supporting partial wetting transparency See . Still, 71112L refers to the liquid surface tension. The vdW interactions per unit area between liquid and substrate, Φ, can be computed from S for any bare solid is identical to ΦGS for the graphene-covered surface. θGS, and the contact angle on the bare solid, θS. The previous studyGS is the Φ for free standing monolayer graphene, which implies that the upper bound of θGS is the contact angle of the monolayer graphene (θGS > 120°) was reported for the conformal graphene film on a rough copper surfaceθGS = 0° for any solid with θS<105° , Wenzel (W), and Cassie-Baxter (CB) states  states 14. We thThe conventional wetting theory holds only if the surface texture has a certain characteristic length scale in roughness because it assumes that the liquid-solid interfacial energy is given by the product of the bulk liquid-solid interfacial energy and the effective area of liquid-solid contactθGS and θS for the flat surface by calculating the ΦGS and ΦS (see Methods for details). As in the previous studyθS from 0° to 180° by gradually increasing the value of ρSASL from 0 to 11.7 eVÅ3, and compute θGS for the corresponding range of ρSASL to get θGS − θS relationship. Then, the equilibrium wetting mode on the rough surface is determined by the minimum free energy principle, as demonstrated for the GRSR model with r = 1.5 and f = 0.5 in θ′S on the rough bare substrate , as depicted in We obtain the relation between ubstrate  and θ′GSubstrate . Combinif ≤ 1). It is known that a graphene layer floats on the surface when graphene grown by another surface is transferredθ′S and θ′GS by following the procedure used in θ′GS. Most rough substrates are found to have a contact angle around the contact angle of monolayer graphene 96°, the upper bound for the GFSR mode. The measurements lie within the curves with f ≤ 0.5 regardless of the choice of r. The contact angle above 96° can be explained only if we consider a more complex model in which rough graphene is non-conformally adhered to the rough substrate , and we can conclude that flat graphene monolayer is partially transparent for hydrophilic surfaces. However, in the presence of the surface roughness, three different wetting modes must be considered to determine the equilibrium as well as metastable contact mode to explain the experimental data. When a flat graphene layer is covered on a rough surface, the contact angle of the free standing graphene becomes the upper bound of θGS. For a wrinkled graphene  placed on rough bare surfaces, a contact mode with higher θGS can be formed. In addition, we show that the wetting transparency of graphene double or more layer is negligible, which implies that multilayer graphene covered surface can be treated as a pure graphite surface in terms of its wetting characteristics.Based on the theoretical and computational analyses, we provide a comprehensive view on the wetting transparency of graphene. At a first glance, the contact angle measurements on bare and graphene-covered surfaces can be interpreted as an evidence for the wetting transparency for a wide range of contact angles (20° ~ 120°) because they scatter around the perfect wetting transparency line. We show that the observed correlation is a coincidence and cannot be explained by a single universal curve. When a flat graphene layer is covered on a flat surface, the wetting behavior can easily be understood by computing the vdW interaction with the liquid modulus effect. The upper bound of In conclusion, we study the wetting transparency of graphene by accurately calculating the vdW interaction energy for various wetting modes. We reveal that the observed partial wetting transparency cannot be explained without accounting for the bulk modulus and the surface roughness. We also find that this partial wetting transparency almost vanishes for double or more layers of graphene sheets. A natural extension of our work is the research on ionized substrates where coulomb interaction becomes significant, and more complex rough surfaces. We believe that our study can provide a more complete picture of the seemingly partial wetting transparency of monolayer graphene and can be applied to understand wetting phenomena in various circumstances.et al.CL are the distance and the vdW parameter between the two entities. Summing up the vdW potential from all pairs of a liquid molecule and carbon atoms, the vdW interaction between one liquid molecule and a flat, infinitely large monolayer graphene sheet is given by 0=3.35 Å is the interlayer distance between the graphitic planes. Ignoring the bulk modulus of the liquid, the density profile of liquids molecule were computed from the Boltzmann distribution, First, we briefly review the vdW ineraction calculation presented in Shih NL(z) was written as th layer and the liquid. The shortest distance δGL between the uppermost graphene and the liquid was set to be 3.28 Å, according to the MD results. However, the integral in the square brackets underestimated the vdW interaction from all layers except i = 1, because the liquid density at the bottom  refers to the liquid density profile above the entire surface, and S is the density of the substrate and ASL is the vdW interaction parameter between one solid atom and one liquid molecule. On the other hand, the vdW interaction per unit area between the liquid and the bare solid was calculated without any mathematical error by δSL is the distance between the liquid and the bare solid. θS is tuned from 0° to 180° by gradually increasing the value of ρSASL from 0 to 11.7 eVÅ3, and θGS is also computed for the corresponding range of ρSASL.Here, We stack graphene films on an arbitrary solid substrate with the contact angle 45°, and calculate contact angles as we add more graphene layers on top . We prepHow to cite this article: Kim, D. et al. Solving the Controversy on the Wetting Transparency of Graphene. Sci. Rep.5, 15526; doi: 10.1038/srep15526 (2015).


We have successfully fabricated and characterized highly uniform nanopatterned graphene (NPG). Thin anodized aluminum oxide nanomask was prepared by facile self-assembly technique without using polymer buffer layer, which was utilized as a direct-contact template for oxygen plasma etch to produce near-periodic, small-neck-width NPG. The NPG exhibits a homogeneous mesh structure with an average neck width as small as ~11 nm. The highly uniform 11-nm neck width creates a quantum confinement in NPG, which has led to a record bandgap opening of ~200 meV in graphene for the given level of neck width. Electronic characterization of single-layer NPG field-effect transistors (FETs) was performed, which demonstrated a high on-off switching ratio. We found that the NPG allows for experimental confirmation of the relationship between electrical conductance and bandgap. This work also demonstrates that our direct-contact, self-assembled mask lithography is a pathway for low-cost, high-throughput, large-scale nanomanufacturing of graphene nanodevices. Graphene has recently emerged as a new and exciting 2D material due to its remarkable properties including high charge mobility, mechanical strength, and flexibility –3. Poten5 is needed. One way to open a bandgap in graphene is to create geometrical constrictions of graphene material. This will lead to the confinement of electrons thus opening a bandgap. In order to increase the driving current for practical applications, such geometrical constrictions need to be maximized by fabrication of dense, ordered nanoribbon arrays, which has been achieved by electron-beam lithography [However, due to the semimetallic nature of graphene, it lacks a bandgap, which is necessary for technological applications such as FETs. Hence, this results in a very low on/off ratio in graphene field-effect transistor devices. For practical applications, an on/off ratio on the order of 10hography , 12. AltTo advance a facile process technique for nanopatterned graphene (NPG), we have specifically utilized an anodic aluminum oxide (AAO) lithography as it can be scaled to large-area substrates with high fidelity of patterning, which can be compatible with conventional lithographic processes , 14. WitHere, we report the production of a graphene nanostructure that can open up a bandgap in a large sheet of single-layer graphene (SLG). We focus on experimental investigations in SLG FETs and the implications for the device performances. The patterned graphene is prepared by self-assembled mask lithography using a floating AAO that can be placed on the device surface by lift-up of the device from underneath. Such nanostructuring process can effectively open up a conduction bandgap in a large piece of graphene, e.g., by using a several-centimeter-sized AAO membrane. We expect that the relative ease of our AAO lithography technique which can be implemented and scaled to large areas, together with the demonstrated effectiveness in controlling the electronic properties of graphene, will be useful for efforts toward practical large area, commercial applications of graphene in electronics, thin-film devices, flexible electronics, optoelectronics, and sensing.2 solution for 10 min. Any residual Cu debris adhered to the bottom of the AAO barrier layer was removed by placing the sample in nitric acid for a few seconds and washed in DI water immediately after. The barrier layer in the bottom of the AAO holes was then removed by a 5 wt% phosphoric acid etching for 10 min to 2 h.A 0.5-mm thick annealed Al foil purchased from Alfar Aesar (99.99 %) was used as the starting material. The Al foil was successively degreased by acetone and isopropyl alcohol with ultrasonication, followed by deionized (DI) water rinse and nitrogen gas blow. The Al foil was slightly etched in a 1 M NaOH aqueous solution to remove any possible surface contaminations prior to surface-smoothing electropolishing process conducted at 20 V in a solution of perchloric acid (70 %) and ethanol (99.9 %) (1:4 volume ratio) at 5 °C for 15 min, using a Pt counter electrode. Then, a two-step anodization process of the Al foil was carried out by incorporating the Al foil as the working electrode and Pt as the counter electrode, immersed in 0.3-m oxalic acid. The electrolyte temperature was maintained at 1 °C during the anodization process using a powerful refrigeration bath  in which the coolant circulates a double-wall glass chamber. After the first anodizing process, which took about 3 h at an operating voltage of 40 V, the anodized Al foil was immersed for 1 h in a mixed solution of phosphoric acid (6 wt%) and chromic acid (1.8 wt%) kept at 75 °C to remove the alumina layer formed in the first anodizing step. The second anodizing step was implemented for 10 min while other experimental conditions were unchanged compared with the first anodizing step, in order to form an ordered porous alumina membrane on the Al foil. Then, the Al metallic substrate underneath the AAO layer was selectively removed with a mixed HCl and CuCl2 plasma etching. The graphene film was then transferred onto a 300-nm SiO2-coated Si substrate (Si/SiO2) using chemical processing steps. The chemical process for graphene transfer consists of the etching of Cu foil, transferring the floating graphene onto a Si/SiO2 substrate by lift-up in an aqueous solution bath, followed by washing with water, acetone, and isopropyl alcohol as described elsewhere [2 substrate by heating to 400 °C under a N2 atmosphere to remove the residual PMMA and promote the adhesion between graphene and the oxide layer.A single-layer graphene was purchased from ACS material . Before graphene on Cu backing layer was separated and transferred to other substrates, the back side of graphene was first removed by oxygen plasma. The top side of graphene was protected by a PMMA layer coating during the Olsewhere . After t2 substrate from underneath. After that, the sample was annealed in a vacuum at 180 °C for 2 h, in order to allow the AAO membrane to stick tightly on the graphene surface. Then, oxygen plasma  was applied through the AAO template holes to etch and create pores on the graphene. The details of recipes and procedures for the formation of NPG were explained in previous study [The prepared AAO template floating in water was placed on the graphene as an etch mask by lifting up the Si/SiOus study .2-bonded structure of the graphene [+ laser of a wavelength of 514 nm for quantifying the degree of structural order and charge transfer characteristics. To measure the sheet resistance of graphene nanomesh (GNM), Jandel Four-Point Probe was employed for the four-point measurement. The optical property of the graphene samples was characterized by UV/Vis spectrophotometer (UNICO SQ-4802).The sample microstructure was characterized by ultra-high resolution scanning electron microscopy . Raman spectroscopy was used as a nondestructive tool for probing the edges and the crystalline spgraphene . Raman s4)2S2O8. The floating graphene in water was transferred onto a Si/SiO2 substrate. We used the SiO2-coated Si (Si/SiO2) substrate for electrical measurements of the FET device. The AAO membrane was placed on graphene, and the transferred AAO membrane was used as the etch mask for the fabrication of NPG. After the oxide template was placed on top of graphene, O2 plasma etching was employed to generate nanopores in the graphene layer. Finally, the AAO mask was etched away by a NaOH solution, and the sample was washed with acetone. The AAO membrane prepared by a two-step anodization of high-purity aluminum foil and this self-assembly fabricated AAO membrane was used as a mask during the oxygen plasma etching of graphene for nanopore array formation  and 2D (~2682 cm−1) bands were prominent. The D peak at ~1341 cm−1 is related to defects and disorder. This is forbidden in perfect graphitic systems and requires a defect for its activation, and so is observed at the edges of graphene samples [ID/IG) is a parameter sensitive to defect density [ID/IG increased by a factor of 3, which suggests that defects in our sample are significantly formed by nanopatterning and pore edge formation. After nanopatterning, there is a systematic upshift in the position of the G band. The G band position for porous graphene was observed at ~1594 cm−1, which can be compared with the G position of pristine graphene (~1586 cm−1) in our sample. This upshift in the G band position further confirms the hole doping in the NPG by the formation of oxygen dangling bonds with graphene, as reported by previous research [IG/I2D with more defects. The increase in the IG/I2D in NPG is due to the alteration of its electronic transformation from semimetallic to semiconducting with successive opening of bandgap [Raman spectroscopy was used as a nondestructive tool for probing the edge structure and the crystallinity of sp samples –17. The  density . In Fig. bandgap .Fig. 3Co2 etching  serves as drain and source contacts. The 300-nm-thick thermal oxide SiO2 layer and degenerated (p++) Si wafer are used as the gate dielectric and the back gate, respectively. Figure Id) versus gate voltage (Vg) characteristics for the transistor show a typical p-channel transistor behavior  [Ion/Ioff · exp(Eg/kT), where k is Boltzmann constant and T is the absolute temperature) [Ion/Ioff value of a NPG transistor is expected to inversely scale with the average neck width, as expressed in Eq.  , 24. Furd in Eq. , where CEquation  can be sEg ~ α/w by an average neck width of ~10 nm was 95 MeV. In Fig. Ion/Ioff value of 50. By contrast, the FET device with a larger 25-nm neck-width NPG exhibits an order of magnitude smaller Ion/Ioff ratio of ~5.3 with much less bandgap opening as shown in Fig. We have achieved the current on/off ratio values significantly higher than those in the previously reported FET devices of graphene nanoribbon (GNR) and graphene nanomesh (GNM) –25. The Electrical characterization of NPG confirmed that the current on-off ratio is inversely proportional with the neck width, indicating the formation of an effective gap due to the confinement effect. We have shown that both electronic transport and Raman characteristics change in a concerted manner on graphene patterning. The availability of such well-controlled NPG structure will provide an interesting possibility for a more in-depth fundamental investigation of transport behavior in the highly interconnected graphene network, and will enable exciting opportunities in sensitive electronics and sensor devices.We demonstrate a successful fabrication of very fine dimension NPG using a thin-floating anodic aluminum oxide (AAO) membrane etching mask. The membrane was directly transferred onto a hydrophobic graphene surface for well-adhered and stacked manner on the graphene due to the van der Waals force, thus allowing a high-density, small-neck-width NPG structure fabrication, without using any intermediate buffer/adhesion polymer which could adversely affect the resolution of plasma etching patterning of graphene. The NPG so produced exhibits homogeneous mesh structures with an average neck width as small as ~11 nm. Electronic characterization of a single-layer NPG FET structure with an 11-nm neck width creates a quantum confinement in NPG, which has led to an impressive bandgap opening of ~200 MeV. The NPG structures with different neck widths allowed experimental confirmation of the relationship between electrical conductance and bandgap. Electrical characterization of the NPG-based FET device confirmed that the current on/off ratio is inversely proportional with the neck width, indicating the formation of an effective gap due to a confinement effect. The availability of such NPG will provide an interesting system for a more in-depth fundamental investigation of transport behavior in the highly interconnected, small-width graphene network and will enable exciting opportunities in sensitive electronic or sensor devices. This work also demonstrates that self-assembled mask lithography is a pathway for low-cost, high-throughput, large-scale nanomanufacturing of NPG with critical dimensions down to nanometer regime.


Sonoelastography is a novel and promising imaging tool, which has been applied to breast, thyroid, and prostate tissues. The aim of this study was to evaluate focal lesions of the testes with diameters of <10 mm using sonoelastography, B-mode sonography (US), and colour Doppler ultrasonography (CDU).Thirty patients who were referred to our outpatient clinics for varicocoeles, scrotal pain, scrotal enlargements, epididymitis, palpable testicular nodules, or infertility, were prospectively enrolled into this study. Ultrasound evaluations had revealed that 27 subjects had focal testicular lesions with diameters of <10 mm and 3 subjects had 10-mm spherical non-homogeneous testicular nodules. All lesions were evaluated using semiquantitative sonoelastography, and the patients underwent orchifunicolectomies. The testicular lesions were examined histopathologically. The vascularization of the lesions and the surrounding testicular parenchyma was evaluated by analysing the immunohistochemical distribution of the cluster of differentiation 31 and by calculating the vascular indices (VI). Potential associations between the strain ratios (stiffness of the lesions) and the VI were tested.P < 0.001).Analyses of the strain fields obtained using semiquantitative sonoelastography yielded different values for the masses and the surrounding tissues, which led to significant increases in the strain ratios. Sonoelastography upheld all of the diagnoses that were suspected when the patients were physically examined, when the serum markers were analysed, and after the patients had undergone US and CDU. Histopathological examinations confirmed the neoplastic characteristics of these masses. A significant inverse correlation was determined between the sonoelastographic strain ratio and the VI (Pearson correlation coefficient, r, = − 0.93; Our investigation shows that semiquantitative sonoelastography may provide additional objective information to support the algorithm used to diagnose testicular lesions. This might be of crucial diagnostic importance for lesions with diameters of <10 mm, particularly if they are not palpable, are negative for serum tumour markers, and if the findings from ultrasonography and CDU are equivocal. The findings from semiquantitative sonoelastography might indicate the need for surgical exploration. Further investigations with larger numbers of patients are required to corroborate these data and to support the use of semiquantitative sonoelastography in the evaluation of testicular lesions. Ultrasonographic elastography, or sonoelastography, is a novel diagnostic modality that is under investigation for its clinical application to cancer diagnostics -4], and, and4], An important characteristic of a tissue is its inherent elasticity, which may be altered by the pathophysiological processes associated with ageing, inflammation, and the presence of tumours. In this context, elasticity is defined as the tension (i.e. stress) needed to produce a relative change in length (i.e. strain), and it describes the amount of pressure that must be exerted on a tissue to achieve elastic deformation. In principle, elasticity can be derived from the stress and strain parameters measured in tissue structures. While strain can be computed from high-frequency echo signals, stress cannot be directly determined from tissue measurements. During ultrasonographic examinations of tissues, compressibility is a standard parameter that is considered in the differential diagnoses of lesions. A non-compressible mass detected during B-mode sonography (US) is associated with an increased likelihood of malignancy. Sonoelastography is based on strain imaging, and preliminary data on a possible role for sonoelastography in the evaluation of testicular lesions have been reported -17]. Th. Th17]. Between March 2010 and January 2013, 30 male patients with an average age of 37 years (range 22–50 years), presented with the following findings: 9 patients had scrotal enlargements, 6 of whom had unilateral epididymitis and 3 of whom had idiopathic scrotal pain; 7 patients had palpable hard testicular nodules, 4 of whom were referred to our clinic because of varicocoeles; and 14 patients visited our outpatient clinic because of infertility issues and they did not present with any palpable lesions.All patients were investigated using US and colour Doppler ultrasonography (CDU), which enabled the presence of testicular lesions to be confirmed, their largest diameters to be calculated, and their vascular configurations to be explored.These lesions were then evaluated using semiquantitative sonoelastography (ElastoQ). The patients underwent orchifunicolectomies within 1 week of their diagnostic algorithms being fulfilled, which included the evaluation of tumour markers in the serum. Histopathology was performed on all of the lesions.The study was performed according to the principles of the Declaration of Helsinki 2000. Local ethics committee approval was obtained (ASL Lt/no.12985678), and written informed consent was acquired from all patients.Semiquantitative sonoelastography was performed while the patient rested in a supine position on a bed, using the Aplio XG Colour Doppler System  equipped with a 5–14-MHz linear transducer. The probe was placed on the testis while applying light pressure. At this time, the operator can see a curve representing the entity and the mode of compression in the lower portions of the display. This allows the operator to analyse the shape of the compression/decompression curve and verify that the amount of compression is optimal. Semiquantitative sonoelastography software calculates the strain ratio, with the terminal phase of decompression being selected for the calculation, because it is less dependent on the force exerted and is therefore more consistent.During sonoelastography, the operator highlighted the nodule being evaluated, and this was referred to as the region of interest (ROI). The ROI was manually drawn to correspond with the nodule and it was at an elevation plane that corresponded with the extralesional parenchyma. The size of the ROI was defined by the operator as the area of abnormal tissue selected. Another area of the same size as the ROI was then selected within the normal tissue to enable the areas to be compared and to determine the strain ratio. Two ultrasonic images were acquired during sonoelastography: one was acquired before tissue compression by the probe and the other was obtained after tissue compression. Tissue displacement was tracked by assessing the propagation of the imaging beam, and tissue distortion was accurately measured using the dedicated software. Once the raw data had been acquired, a chromatic map was superimposed onto the US image using a colour scale that ranges from red, indicating components with the greatest elastic strain (i.e. the softest components), to blue that indicates components with no elastic strain (i.e. the hardest components).In this study, the sonoelastographic images were matched with an elasticity colour scale and classified using the elasticity score developed by Ueno and Itoh . The strTo calculate the strain, we chose the optimal decompression value for each lesion. This enabled the strain ratio of the ROI to be obtained by comparing the elastic characteristics of the lesion with the elastic characteristics of the normal tissue. The echogenicity ratio was determined by comparing the echogenicity of the lesion with that of the normal tissue using the greyscale function. It is possible to define ElastoQ as a modification of the real-time method, because it allows off-line analysis of the deformation values (i.e. strain) of a mass while utilizing the raw data generated by changes in radiofrequencies before and after tissue compression. The calculation is performed by selecting an ROI within the lesion under investigation and a reference region in an area of normal parenchymal elasticity. The result is an index of deformation (i.e. strain index) that is relative to the reference value of the tissue. The strain index increases as the rigidity of the structure being examined increases. This method can also be used to determine a lesion’s degree of echogenicity by comparing it with nearby normal structures, while considering the absolute values of echogenicity expressed in the raw data.All of the patients underwent orchifunicolectomy. The surgical specimens from the primary tumours were submitted for histological examination in 10% neutral-buffered formalin, and were then processed and embedded in paraffin wax. Sections were cut at 5 μm and stained with haematoxylin and eosin. Two pathologists reviewed the sections and categorized the tumours using the World Health Organization’s histological classification of testicular cancer. Immunohistochemistry was performed using the Bond Polymer Refine Detection system  and the cluster of differentiation (CD) 31 antibody , at a dilution of 1:100, to determine the distribution of CD31, and hence the vascularization of the primary tumours and the surrounding testicular tissues. Two pathologists evaluated these sections at a 10× magnification .When examined by US, 27/30 patients had subcentimetre hypoechoic lesions and 3 patients had 1-cm non-homogeneous spherical lesions. Only 7/30 lesions showed clear evidence of increased vascular flows when examined by CDU. The findings in these 7 patients combined with the positive lesional palpations detected during the physical examinations, which raised suspicions about the presence of neoplastic disease, prompted us to assess all of the patients for the presence of the following tumour markers: alpha-fetoprotein, carcinoembryonic antigen, human chorionic gonadotropin, and lactate dehydrogenase. Only 4/30 patients were positive for these tumour markers.P < 0.001)  Figure . The cliTesticular masses can be difficult to diagnose, particularly when they have a diameter of <1 cm and/or are not palpable. Palpation provides subjective data, but physicians need instrumental support to make informed decisions about therapy when the lesion is small. Evaluations using US combined with CDU are commonly used to characterize testicular lesions, but these evaluations do not provide any information about the internal consistency of the masses. This information might help to corroborate diagnostic assessments, especially when masses with small diameters are found incidentally. Sonoelastography can be used to evaluate the mechanical elastic properties of soft tissues, which are determined by their macromolecules and structural organization. This is the first report describing the use of semiquantitative sonoelastography to investigate subcentimetre testicular masses, which could be promising potential targets for this new imaging technology. Indeed, the information obtained through sonoelastography in this study has contributed to the diagnostic evaluation of testicular lesions, because it has given an insight into their atypical compositions and it has emphasized the need for a high level of clinical suspicion about malignancy in the context of subcentimetre testicular tumours. Our data concur with those from previously reported studies -17] and and17] aSonoelastography evaluates the radiofrequencies that arise from structures before and after they are subjected to manual or mechanical compression. Manual compression and mechanical compression are the different sonoelastographic techniques used to cause deformation of the structures under investigation. The intensity of the change in the radiofrequency of the ultrasound pulse rises as the severity of the deformation and the elasticity of the tissue increase. The evaluation of the strain or deformation induced by manual compression is a clinically proven method for the evaluation of tumours -4],11],[11]4],4],.This technique does not require any additional hardware, and it only requires the software associated with the sonoelastographic system . The datSonoelastographic results can be affected by several factors including coarse calcifications, cysts, and out-of-plane displacements, which can compress the lesion under examination. However, the testis is mobile and it is not adjacent to any bony structures. Since real-time sonoelastography is based on the superimposition of polychromatic maps of elasticity onto 2-dimensional images, elasticity is determined subjectively and nodular lesions are scored from E1 to E5 in accordance with the mapping scheme defined by Ueno and Itoh .In our study, we sought to substantially reduce the subjectivity associated with evaluating the colour maps in real time by replacing the classification system with a numerical parameter, that is, the strain ratio, which is not operator dependent, is reproducible, and enables the elasticity of lesions to be given unique classifications. To ensure the objectivity of the assessment, we also attempted to define a cut-off value that would differentiate between likely benign nodular lesions and likely malignant lesions, and to add a numerical parameter that would help guide the next clinical step, for example, clinical monitoring with or without treatment, or surgical excision. This was possible with the semiquantitative sonoelastography system, because it expresses the deformation capacity of the structure under investigation relative to the normal (reference) tissue as an absolute value or as a strain ratio. Therefore, semiquantitative sonoelastography represents a modification of the real-time method and enables the off-line analysis of a nodule’s strain values by analysing variations in radiofrequencies using the raw data. The calculation is performed by selecting an ROI within the nodular formation and a reference region in an area of normal parenchymal elasticity. The result is an index of deformation (i.e. a strain index or a coefficient of elasticity) that can be compared with the organ’s reference values, and that rises as the rigidity of the structure being examined increases. Using this method, the coefficient of echogenicity can also be determined by comparing the echogenicity of the lesion with that of nearby normal structures, while taking into account the absolute values of echogenicity expressed in the raw data.In a preliminary study, Grasso et al.  used sonOur experience demonstrates that semiquantitative sonoelastography is a viable option for the evaluation of testicular nodules, and that it might offer an instrumental option that could support conventional ultrasonographic approaches in the diagnostic algorithm for testicular nodules, especially in the diagnosis of ambiguous and non-palpable lesions. The findings from this study suggest that tumours emit signals indicative of stiffer tissues, especially in the region around a tumour’s perimeter. Given that this was found in all of the tumours examined, signals indicative of stiffer tissues within suspicious echographic areas of the testis might be considered reliable indicators of pathological tissues. In the current study population, only 4 patients were positive for tumour markers in their sera, 27 individuals had subcentimetre lesions, and only 7 individuals had palpable masses. Hence, not all of the subjects had definitive diagnoses of neoplastic disease.The data generated by semiquantitative sonoelastography provide further evidence that the lesions discovered during the physical examinations, US, and CDU were pathological, which prompted surgical treatment. Furthermore, the immunohistochemical analysis undertaken in our study demonstrated a linear inverse correlation between the strain ratio values and the VI. It could be postulated that this inverse correlation is an expression of the lesions’ diminished consistencies and greater intralesional vascularity. This finding could be further interpreted as hypervascular tumours having lower levels of consistency than hypovascular tumours. Hence, sonoelastography could quantify the magnitude of intralesional microcirculation or neoangiogenesis, and substantiate the consistency of testicular masses. Together, these add important elements to diagnostic and prognostic assessments. Given that the main limitation of the present study was the small number of patients, further investigations with larger numbers of patients are required to corroborate these data and to support the use of semiquantitative sonoelastography in the evaluation of testicular lesions.Among the patients studied, we found that semiquantitative sonoelastography provided valuable additional objective information about solid testicular lesions, which was of crucial diagnostic importance, and that it confirmed the need for surgical exploration, particularly when the tumours were <10 mm in diameter. The results from this patient series indicate that semiquantitative sonoelastography is a promising adjunctive modality for evaluating the consistency and microvascularity of testicular lesions. However, future studies using larger numbers of patients are necessary to validate these data.CD: Cluster of differentiationCDU: Colour doppler ultrasonographyROI: Region of interestUS: B-mode sonographyVI: Vascular indicesThe authors declare that they have no competing interest.All authors contributed equally to drafting the manuscript. All authors read and approved the final version of the manuscript.


APOE) genotype ε3/ε3 or ε3/ε4, the presence of a very long (VL) polyT repeat allele in “translocase of outer mitochondrial membrane 40” (TOMM40) was less frequent in patients with sporadic inclusion body myositis (sIBM) compared with controls and associated with a later age of sIBM symptom onset, suggesting a protective effect of this haplotype. To further investigate the influence of these genetic factors in sIBM, we analyzed a large sIBM cohort of 158 cases as part of an International sIBM Genetics Study. No significant association was found between APOE or TOMM40 genotypes and the risk of developing sIBM. We found that the presence of at least 1 VL polyT repeat allele in TOMM40 was significantly associated with about 4 years later onset of sIBM symptoms. The age of onset was delayed by 5 years when the patients were also carriers of the APOE genotype ε3/ε3. In addition, males were likely to have a later age of onset than females. Therefore, the TOMM40 VL polyT repeat, although not influencing disease susceptibility, has a disease-modifying effect on sIBM, which can be enhanced by the APOE genotype ε3/ε3.A previous study showed that, in carriers of the apolipoprotein E ( Given i in sIBM , but no  in sIBM . Recentlith sIBM . That stsymptoms . To furt2APOE genotyping. Fluorescence-based fragment size analysis was performed for genotyping the polyT repeat in intron 6 of the TOMM40 gene (rs10527454). The polyT repeat alleles were classified based on the length of repeat (N) as originally established by APOE and TOMM40 polyT were compared between cases and controls using the chi-square or the Fisher's exact test. The associations between APOE genotypes, TOMM40 polyT genotypes, ethnicity, gender, and age of onset of sIBM were analyzed by linear regression analyses. For all the analyses, p value <0.05 was considered statistically significant  were collected from 9 centres around the world. The control group comprised 127 individuals with no history of neuromuscular disease. Restriction fragment length polymorphism was used for 3APOE ε2/ε2 genotype was absent in both the sIBM cohort and the control group. No significant differences were found between patients and controls regarding APOE allelic and genotypic frequencies, considering neither only Caucasian patients nor the entire cohort. The distribution of TOMM40 polyT repeat lengths was similar in the sIBM group (range 8–36 repeats) and controls (11–33 repeats)  . The fren groups . When thIBM risk .APOE alleles and the age of onset of sIBM. However, being a carrier of the polyT repeat, VL allele was significantly associated with a later age of onset by 3.7 years in average . We repeated the analysis just for carriers of the APOE ε3/ε3 genotype. We found that APOE ε3-TOMM40 VL allele carriers had an even later age of onset of sIBM by 4.9 years in average . Similar results were found when the analysis was restricted to Caucasians . Although not reaching statistical significance, there was also a trend for a later age of onset (by 2.7 years) in males compared with females (There was no significant association between different  females .4APOE and TOMM40 genes in sIBM disease risk and features has been investigated. Concerning APOE, our findings confirmed that the APOE ε4 allele is not a susceptibility factor for developing sIBM, which is consistent with the previous studies (APOE alleles were also not significantly associated with the age of onset of the disease. In addition, our findings did not replicate a previously reported association between APOE-TOMM40 and risk of developing sIBM (APOE ε3/ε3 genotype. This suggests that the TOMM40 VL polyT repeat has a disease-modifying effect on sIBM by delaying the onset of symptoms, and the APOE ε3/ε3 genotype enhances this effect. Although the association between APOE and TOMM40 and sIBM risk was not confirmed in our study, the finding of an association between the TOMM40 VL polyT repeat and a later age of onset of sIBM may justify further gene expression studies in the future. In addition, there might be other variants within the APOE-TOMM40 locus involved in the susceptibility to sIBM. Furthermore, identification of new genes and variants is crucial to improve our understanding of this complex disease.This is the largest cohort where the influence of the  studies . APOE aling sIBM . HoweverThe authors have no conflicts of interest to disclose.


Based on the necessity for enclosure protection of temperature and relative humidity sensors installed in a hostile environment, a wind tunnel was used to quantify the time that the sensors take to reach equilibrium in the environmental conditions to which they are exposed. Two treatments were used: (1) sensors with polyvinyl chloride (PVC) enclosure protection, and (2) sensors with no enclosure protection. The primary objective of this study was to develop and validate a 3-D computational fluid dynamics (CFD) model for analyzing the temperature and relative humidity distribution in a wind tunnel using sensors with PVC enclosure protection and sensors with no enclosure protection. A CFD simulation model was developed to describe the temperature distribution and the physics of mass transfer related to the airflow relative humidity. The first results demonstrate the applicability of the simulation. For verification, a sensor device was successfully assembled and tested in an environment that was optimized to ensure fast change conditions. The quantification setup presented in this paper is thus considered to be adequate for testing different materials and morphologies for enclosure protection. The results show that the boundary layer flow regime has a significant impact on the heat flux distribution. The results indicate that the CFD technique is a powerful tool which provides a detailed description of the flow and temperature fields as well as the time that the relative humidity takes to reach equilibrium with the environment in which the sensors are inserted. Technological development with respect to instrumentation systems and measures increasingly demands the means to provide greater reliability of the data collected.Computational fluid dynamics (CFD) simulations are increasingly used to predict various issues in agriculture and food processing Protective housing for temperature and relative humidity sensors is normally required to prevent damage due to the physical and environmental influences on agricultural processes. A major concern about protected temperature and relative humidity sensors is the response time delay in a process reaching equilibrium with its environment, which may affect its accuracy if the measurement is taken at an inadequate time.The main objective of this work was to identify how much time it takes for temperature and relative humidity sensors to respond properly in a dynamic varying process, under certain specified operational conditions.As a first step, experiments were performed in a wind tunnel, and CFD simulations, to predict the distributions of temperature and relative humidity in a non-isothermal flow, were accomplished.A small wind tunnel, 200 mm in diameter and 500 mm high, was designed to provide a laminar flow with a speed between 0.5 and 1 The investigation of the heat exchange and mass transfer between the environment and the housing was divided into two parts: (1) a study of the interface between the fluid medium (air) outside and inside the housing, (2) analysis of the fluid flow (air) at constant speed for high temperature (77.5°C), external to the housing.Measurements were taken at the point closest to the center outside the housing and at the center point inside. The Reynolds number Results were obtained from the standard In order to gain further insight into the heat transfer and mass structures of PVC (polyvinyl chloride) materials and to analyze the behavior of the temperature and relative humidity sensors more deeply, CFD model simulations were performed to investigate the distribution of temperature and relative humidity in the transient regime at the observation points, and the findings were compared with results obtained in the wind tunnel.A data acquisition system, based on 1-Wire technology, with real-time monitoring was implemented using addressable digital devices The 1-Wire network uses only a conductor for data transmission, in common with all instruments or devices (slaves) connected to the network, and a computer or microprocessor (master), which manages the whole system through an appropriate computer program, and is technically and economically feasible The temperature and relative humidity in the wind tunnel were measured at two central points. A sensor without protective housing was placed close to the wind tunnel center and exposed to the air stream. Another sensor with protective housing was installed at the center of the wind tunnel and received the airflow through the perforations made in the housing wall. The average airflow rate was held constant through the wind tunnel. External environmental variables, such as temperature and relative humidity, were also monitored with a sensor without housing.The housing for the circuit with a temperature sensor (DS2438) and a humidity sensor (HIH4000) with 1-Wire technology inside the wind tunnel was constructed using a PVC tube 100 mm long with a diameter of 32 mm. Perforations of 5 mm diameter were drilled into the housing wall to allow for airflow around the sensors, connected by shielded wire pairs, as illustrated in A data acquisition system was programmed using the 1-Wire protocol and based on a system called STRADA As previously discussed, one sensor with protective housing and one without were installed inside the wind tunnel. A third sensor was installed outside the tunnel to monitor the external environment conditions. The sensors were interconnected by a four-way telephone wire to acquire and transmit data The temperature and relative humidity data were recorded with a resolution of The airflow speed in the wind tunnel was set at Due to the complexity of the housing geometry, the ANSYS ICEM CFD software was used to construct a tetrahedral computational mesh of the object under study.The tetrahedral volume element is very useful for maintaining the high quality of the mesh while articulating different forms of complex geometry to be modeled in the region of interest, even though it requires more nodes than the mesh elements and results in a hexahedral file size and increased computation time The results obtained by simulation using CFD were verified and compared with the corresponding data obtained experimentally in the wind tunnel.The measured values and those obtained experimentally in the wind tunnel were used to assign the boundary conditions of the model. Thus, it was necessary to provide the initial values of variables such as relative humidity and air temperature inside and outside the enclosure, calculate the humidity and temperature for each step in time, and solve the equations of conservation of energy, mass and momentum.The CFD technique was used to solve the Navier–Stokes equations written for the velocity and energy fields, quantifying the fields of temperature and velocity by the finite volume method h - Convective heat transfer coefficient m - Mass transfer coefficient hP – Pressure (Pa)T – Temperature (K)T – Time (s) - Dissipation rate of speed fluctuations k - Turbulent kinetic energy coefficient The Reynolds tensor was modeled using the standard turbulence After exposure of the sensors to the airflow for a specific period of time for a given level of humidity, a relative humidity value is reached, which depends on the temperature and the amount of water contained in the air at the equilibrium state.Relative humidity is a measure of the amount of water contained in the air, defined by the ratio between the actual pressure of water vapor in the atmosphere and the pressure of saturated water vapor in the atmosphere at the same temperature, usually expressed as a percentage.The empirical relationship between the saturation vapor pressure and the temperature is given by the following equation The ANSYS CFX computer program was used to implement the proposed model with the following assumptions:Transportation in transient state.Incompressible flow.A residue with a value less than The variables were tested for normality using the Shapiro–Wilk test and subsequently an analysis of variance was carried out. Comparisons between independent replications were performed by analysis of variance for data with a normal distribution and by the nonparametric Kruskal–Wallis test for data without a normal distribution.After the appropriate transformations, data were submitted for nonparametric testing using the SigmaPlot, version 11.0, computer program, from Systat Software Inc. This work was developed at the Departamento de Engenharia Agrícola, Universidade Federal de Viçosa, Viçosa, State of Minas Gerais, Brazil.To solve the problem of heat and mass transfer using CFD, first the behavior of the fluid (air) under two experimental conditions  was analyzed. The behavior of the temperature variation is shown in After the experimental behavior of the fluid (air) in the proposed scenarios was analyzed, the process was modeled. The boundary conditions took into account the temperature at the entrance of the control volume.The temperature of the fluid stream outside the protective sensor's housing was measured, starting at instant zero corresponding to the ambient air temperature until a maximum steady temperature was reached, according to the power and airflow rate of the fan used. A mathematical model was fitted to the experimental data by nonlinear regression analysis. The model that best fitted to the experimental data was an exponential type equation, expressed by y - Temperature (t - Time (s)a, b - Regression coefficientsThe coefficient estimates of the fitted model, along with their standard error, t-statistics values, and probability significance level, are presented in The adjusted coefficient of determination  for predicting the response of temperature and relative humidity sensors inside the protective housing. This is very important to determine the exact instant at which the measurements should be taken to obtain the correct, or at least, a satisfactory value of the measure of interest, principally if the process is taking place in a hostile or dirty environment.The model previously discussed was used to estimate the boundary conditions (input conditions) of the simulation model.In order to accomplish the simulation, ICEM ANSYSTM software was used to generate meshes for the system. A tetrahedral mesh was created with a total of 356,654 finite volumes comprising two distinct domains: (1) formed by the fluid confined in the protective housing consisting of 217,069 finite volumes, and (2) formed by the unconfined fluid consisting of 139,585 finite volumes. Both domains were interconnected by a fluid-type interface at the openings in the PVC tube. Boundary conditions were established for each face of each domain, as shown in Using During the study period , it was observed that the time for temperature and relative humidity to reach the equilibrium conditions for sensors with and without protective housing differed by 1,020 s and 540 s, respectively, with a variation of It should be pointed out that these results are for a particular case and, certainly, may vary for other conditions or processes. However, they give an indication of how to proceed when measuring temperature and relative humidity, for example, in the mass of a biological product, such as cereal grains.A high correlation was found between the measured and simulated temperature inside the sensor's housing, as well as between the measured and simulated relative humidity inside the sensor's housing, as shown in It can be seen in As a material of high resistance and low cost, PVC tubes are appropriate for housing sensors exposed to hostile environments.The results obtained from simulations of temperature and relative humidity show a good correlation with experimental data .Video S1Temperature and relative humidity variation.(AVI)Click here for additional data file.


We developed a simple, scalable and high-throughput method for fabrication of large-area three-dimensional rose-like microflowers with controlled size, shape and density on graphene films by femtosecond laser micromachining. The novel biomimetic microflower that composed of numerous turnup graphene nanoflakes can be fabricated by only a single femtosecond laser pulse, which is efficient enough for large-area patterning. The graphene films were composed of layer-by-layer graphene nanosheets separated by nanogaps (~10–50 nm), and graphene monolayers with an interlayer spacing of ~0.37 nm constituted each of the graphene nanosheets. This unique hierarchical layering structure of graphene films provides great possibilities for generation of tensile stress during femtosecond laser ablation to roll up the nanoflakes, which contributes to the formation of microflowers. By a simple scanning technique, patterned surfaces with controllable densities of flower patterns were obtained, which can exhibit adhesive superhydrophobicity. More importantly, this technique enables fabrication of the large-area patterned surfaces at centimeter scales in a simple and efficient way. This study not only presents new insights of ultrafast laser processing of novel graphene-based materials but also shows great promise of designing new materials combined with ultrafast laser surface patterning for future applications in functional coatings, sensors, actuators and microfluidics. Surface micro/nano patterning is a highly promising approach to control the optical, electrical, chemical, biological, mechanical and other properties of a solid surface1246781313 w/cm2) and ultrashort irradiation periods, fs laser fabrication presents unique advantages of nonlinear nonequilibrium processing212225In general, scalable methods used to create surface patterns can be divided into two categories: bottom-up methods such as chemical synthesis, self-assembly and dip-pen nanolithography1551819In this study, large-area uniform 3D rose-like microstructures were fabricated using fs laser pulses. The 3D rose-like structure can be obtained by only one laser pulse, which offers great potential for the high-throughput large-scale manufacturing. The home-made freestanding graphene films, prepared from direct filtration of the aqueous reduced graphene oxide colloidal suspensions, were composed of both nanoscale graphene nanosheets separated by nanogaps and subnanoscle graphene monolayers with a large interlayer spacing of ~0.37 nm. The unique hierarchical structure offers great potential for the generation of tensile stress during fs laser ablation, which acted as a driven force for rolling up the graphene nanoflakes. Our approach shows potential application in fabrication of centimeter-scale 3D micro/nanostructures in a controllable and highly-efficient manner, which is distinct from earlier reports in that the graphene film itself served as an important precursor for the formation of graphene microflowers when it was processed with fs laser pulses.v), and scanning pitch (2) shows superhydrophobility with a large water contact angle of 150°, whereas the original graphene film only exhibits hydrophilicity with a low water contact angle of 78°  to 4 J/cm2 (more than 20 times larger than the threshold), the ablated structures on HOPG films changed from smooth craters to nanoripples to through holes with the increase of the pulse number  of 1.1 J/cm2. At N = 1, several intact and flat graphene flakes were peeled off from the center of the ablated region after a single pulse irradiation, leaving a relative clean and flat surface in the ablation crater (The size and shape of the graphene flower can be further controlled by tuning the laser fluence (F) and pulse number (N), respectively. n crater . The foln crater . In thisn crater . Hence, v), and scanning pitch. The details of the flower density (D) calculation, and the relation between scanning parameters and flower densities were described in 2. It is shown that the graphene microflowers within the scanning area have almost the same geometrical feature, indicating the excellent repeatability. The density of graphene microflowers increases gradually from Large-area micropatterning of graphene films with controllable densities of flower patterns was realized by a simple scanning technique with coordinated adjustments of laser repetition rate, scanning speed , high-density (>1021 cm−3) electrons3434It is worth noting that the microflowers can be obtained on graphene films that have unique hierarchical layering structures, while they cannot be fabricated on HOPG films with a uniform interlayer spacing. On the other hand, the microflowers consist of graphene nanoflakes that were exfoliated from the surface by fs laser pulse, which are geometrically similar to the fragmentation of thin spalls induced by tensile stressIn summary, a simple and efficient method for large-area fabrication of 3D biomimetic microflowers on the graphene films with hierarchical layering structure have been developed using femtosecond laser pulses. The unique structure of the graphene films offers great potential for the generation of tensile stress during femtosecond laser ablation to roll up the graphene nanoflakes for the formation of a complex microflower by only a single laser pulse. Moreover, the size and shape of the microflowers can be precisely controlled by tuning the laser fluence and pulse number, respectively. After large-scale fabrication, the surface of graphene film was covered with uniform arrays of flower patterns with controllable density, exhibiting superhydrophobility and a high retention force to water. The fabricated biomimetic microflowers on the freestanding and flexible graphene films can find broad applications in bionics, microfluidics, sensors, micro/nano-droplets manipulation, single droplet analysis, Janus interface materials for actuators, and in fabrication of lab on a chip that need to retain tiny quantities of liquid without leaking.The graphene films were prepared by direct filtration of aqueous reduced graphene oxide colloidal suspensions through a filter membrane as detailed in our previous reportThe setup of the fabrication system was described in The pump-probe experiments were conducted with the same fs laser. A laser beam was divided into a pump and a probe beam by a beam splitter. The pump beam was focused onto the target surface by a 5 × objective lens. The probe beam was frequency doubled to 400 nm by a beta barium borate crystal. Using a CCD camera, the shadowgraphs of the early plasma were detected.The surface morphology was investigated by a scanning electron microscope . The average interlayer spacing was evaluated by a parallel beam Bruker D8 Advance X-ray diffractometer (XRD). The electrical conductivity was measured using a four-probe conductivity test meter  at room temperature. Raman spectra were obtained using a Renishaw InVia Reflex spectrometer with a 532 nm light source at a low power. The transmission electron microscopy (TEM) was performed using an FEI Tecnai G2 F30 transmission electron microscope. Roughness measurements were carried out using an atomic force microscope . The water contact angles were measured using a K12 tensiometer . X-ray photoelectron spectroscopy (XPS) was carried out using a PHI Quantera X-ray photoelectron spectrometer.How to cite this article: Shi, X. et al. Femtosecond laser rapid fabrication of large-area rose-like micropatterns on freestanding flexible graphene films. Sci. Rep.5, 17557; doi: 10.1038/srep17557 (2015).


Sarcoidosis involves abnormal collections of inflammatory cells (granulomas) which may form as nodules in multiple organs. 90% of affected patients have respiratory tract abnormalities. We present a 61-year-old male with sarcoidosis who was admitted for respiratory distress. Fibrosing mediastinitis was seen in the chest computograph. Management was conservative and included steroids, antibiotics, and oxygen therapy. Sarcoidosis and fibrosing mediastinitis are rare. Fibrosing mediastinitis is more commonly seen with histoplasmosis. We explore the clinical similarities between histoplasmosis and sarcoidosis. We also explore the potential cause and effect relationship and workup for each disease entity. H. capsulatum and causes symptoms that are almost identical to those present with sarcoidosis. Clinicians rely on patient history, lab values, and radiological and pathological studies to distinguish between them. However, there are false negative tests and atypical findings which may complicate the diagnosis. Misdiagnosing one for the other and starting the incorrect treatment plan could cause significant morbidity. In this case, we present a male patient diagnosed with sarcoidosis. History was obtained by personal interview and clinic and hospital medical records. His radiographic finding of fibrosing mediastinitis is rare in sarcoidosis and more commonly seen with histoplasmosis. We review this case to make clinicians aware of the striking resemblance between these two entities and the workup that is recommended to accurately diagnose each disease.Sarcoidosis involves abnormal collections of inflammatory cells (granulomas), which may form as nodules in multiple organs. It is considered a diagnosis of exclusion and most commonly presents with respiratory symptoms. Histoplasmosis is caused by the fungus2 of 57 (on 50% FiO2). Due to his level of respiratory distress, he was intubated with ventilator support. He was treated with antibiotics, steroids, and airway clearance measures. Chest X-ray (CXR) showed extensive fibrocalcific scarring in the upper lobes and compensatory emphysema of the lower lobes  at 18%. Arterial blood gas analysis revealed respiratory acidosis with a pH of 7.27 and COer lobes . Culture Aspergillus. For this reason, oral antifungal therapy was instituted.Our patient first presented with respiratory symptoms at 28 years of age. His symptoms at that time included intermittent fatigue, shortness of breath, a “sore” tongue, and “facial swelling.” While spirometry was normal, his CXR revealed left hilar adenopathy and calcification. Mediastinoscopy was performed, including a mediastinal lymph node biopsy where he was found to have noncaseating granulomas. The fungal cultures and AFB (acid fast bacilli) stains by bronchoscopy were negative. The patient was diagnosed with sarcoidosis and started on prednisone for several months, to which his symptoms responded favorably. For 2 decades, he was treated with inhaled steroids and intermittent courses of prednisone. In his 40s, he presented to an ENT  specialist with uveitis and a hoarse voice. The ENT physician felt that the cause of the hoarse voice was iatrogenic . No biopsy was performed. At the age of 55, a cavitary lesion was detected on chest CT, and sputum cultures were positive forInitial CXRs at the age of 28 showed left hilar and left paratracheal adenopathy. There were also calcified nodules in right and left lung fields. CXRs from the age of 45 through 52 showed progressive upper lobe fibrotic changes. From the age of 52 to 62, the images were stable. The CT scan during the most recent admission was stable as compared to the one done 3 years prior. It showed extensive calcification and soft tissue within the mediastinum with retraction of the mediastinum consistent with fibrosing mediastinitis. Both upper lobes had extensive calcifications and scarring. The esophagus was dilated above the fibrosing mediastinum  associated with sarcoidosis. Devaraj et al. reported two cases in a series of 12 patients with CT images and histology of fibrosing mediastinitis (16% of patients) . There w Histoplasma grew from the liver biopsy specimens [There are other clinical markers which can be used to diagnose sarcoidosis. However, these also can be misleading. ACE (angiotensin converting enzyme) levels are usually only elevated in sarcoidosis but there was a reported case where a patient had elevated ACE levels andpecimens . ACE levpecimens . Noncasepecimens . Histoplpecimens . A positpecimens . However Histoplasma organisms are difficult to visualize in tissues and have often been initially overlooked [ Histoplasma capsulatum has been identified in clinical samples by a highly sensitive molecular marker, a fragment of the Hcp 100 gene. PCR assays for the Hcp 100 gene have been validated in several studies and have shown high specificities [Laboratory methods to diagnose histoplasmosis include cultures, histology, molecular techniques, serology, and antigen detection.erlooked . In addierlooked , 24. Hiserlooked . In receficities –29.In summary, chronic disseminated histoplasmosis and sarcoidosis have strikingly similar features. Diagnostic tests including radiography also have similarities. Unfortunately, applying loose criteria for the diagnosis of sarcoidosis may result in overlooking specific infectious diseases including histoplasmosis. Cultures alone cannot exclude histoplasmosis due to a significant rate of false negatives. As a result, the recommended workup to accurately differentiate between sarcoidosis and histoplasmosis should include radiography, tissue biopsies, cultures, ACE level, serology, PCR assay, and urine antigen. Future studies will be needed to investigate the link between these two diseases.


Graphene has drawn considerable attention due to its intriguing properties in photonics and optoelectronics. However, its interaction with light is normally rather weak. Meta-surfaces, artificial structures with single planar function-layers, have demonstrated exotic performances in boosting light-matter interactions, e.g., for absorption enhancement. Graphene based high efficiency absorber is desirable for its potential applications in optical detections and signal modulations. Here we exploit graphene nanoribbons based meta-surface to realize coherent perfect absorption (CPA) in the mid-infrared regime. It was shown that quasi-CPA frequencies, at which CPA can be demonstrated with proper phase modulations, exist for the grapheme meta-surface with strong resonant behaviors. The CPA can be tuned substantially by merging the geometric design of the meta-surface and the electrical tunability of graphene. Furthermore, we found that the graphene nanoribbon meta-surface based CPA is realizable with experimentally achievable graphene sample. Recently, graphene is been widely investigated for potential applications in photonics and optoelectronics123471113η0 where η0 represents the characteristic impedance of vacuum434445464748495051Artificially engineered photonic structures have been employed as a platform for boosting light-matter interactions for decades15182022232425293031323334353637383940In this paper, we propose a tunable mid-infrared coherent perfect absorber with a graphene nanoribbon based meta-surface. It is found that quasi-CPA frequencies, which is the necessary formation condition of coherent absorption, does exist in the mid-infrared regime for properly designed graphene nanoribbon arrays. The scattering of coherent beams can be perfectly suppressed at the quasi-CPA frequencies with proper phase modulations on the input beams. For the case with two crosses on the transmission and reflection spectra, we can achieve coherent perfect absorption at the two quasi-CPA frequencies, simultaneously. The flexible tunabilities of the graphene meta-surface based CPA are of interests for tunable infrared detections and signal modulations.I+ and I−), O+ and O− are the respective output magnitudes, the graphene sheet is illuminated with perpendicularly polarized light . The meta-atoms, i.e., graphene nanoribbons, are periodically arranged in x-y plane with the lattice  constant and ribbon’s width being P and w, respectively. Both lattice constant and width of the graphene nanoribbon meta-atoms play important roles in determining the optical resonant behaviors of graphene meta-surface, the lattice constant is set to be P = 0.7 μm for the study of CPA in the mid-infrared regime.σg) since a one-atom-thick graphene sheet is sufficiently thin compared with the concerned wavelength. In the theoretical perspective based on random-phase-approximation (RPA)5455EF represents the Fermi energy, μ = 104 cm2V−1s−1 and Fermi velocity vF ≈ 106 m/s.The graphene layer is considered as a sheet material modeled with complex surface conductivity (EF = 0.5 eV. r) and transmission coefficients (t) for the case of graphene nanoribbon meta-surface with width of w = 0.33 μm. We can see an obvious resonance around 23.0 THz. The resonance was confirmed to be electric dipolar mode (which will be verified from the effective surface conductivity below), similar to the low-frequency resonance of split-ring-resonators as that inWe first took O±) of the graphene nanoribbon meta-surface can be related to the two input beams  through a scattering matrix, Sg, defined as:The complex scattering coefficients (t/r)+ and (t/r)− are scattering elements of forward  and backward  beams, since the linear monolayer graphene under investigation is of reciprocity and spatial symmetry, the scattering matrix can be simplified with t± = t and r± = r. Then the amplitude of the scattering coefficients would bewhere  of the input coherent beams leads to significant suppression of the scattering outputs at the quasi-CPA frequencies. The normalized total absorption as a function of frequency for the phase modulation ϕ0 = 1.03π is plotted in To implement the perfect absorption with the graphene meta-surface, we set a chirped phase modulation r and t) of the graphene meta-surface on the widths of nanoribbons. We can see that the resonant frequency of the electric dipolar mode shows a monotonous red-shift with the increase of w, which is similar the cut-wire casex axis. Increasing of the width w or the graphene’ filling factor in the unit cell of the meta-surface leads to stronger light-graphene interaction, i.e. high resonant strength of the electric dipolar resonance, and thus higher r and lower t around the resonance that introduce a regime where w = 0.138 μm, which has its boundary (as the solid line indicated) being the quasi-CPA points. The discrete spheres on top of the solid curve, representing the extracted surface conductivities with The meta-surface structures together with the electrically-controlled graphene will provide more wider tunable space for the design of mid-infrared CPA, we first consider the geometric tunability of the graphene nanoribbon based CPA. μm, the left edge of the solid boundary in On the other hand, the graphene meta-surface is also expected to have higher resonant strength for graphene with larger Fermi level3P = 0.22 μm, w = 0.20 μm) made from experimentally practical graphene, i.e., the Yan et al. graphene with Drude weight τ−1 = 9.8 THz2Here, we also consider a graphene nanoribbon array . The periodic boundary conditions were set for the simulation of periodic graphene nanoribbon structures. The effective surface conductivities of the graphene nanoribbon based meta-surfaces were carried out using a recently proposed sheet retrieval methodHow to cite this article: Fan, Y. et al. Tunable mid-infrared coherent perfect absorption in a graphene meta-surface. Sci. Rep.5, 13956; doi: 10.1038/srep13956 (2015).