Graphene’s unparalleled strength, chemical stability, ultimate surface-to-volume ratio and excellent electronic properties make it an ideal candidate as a material for membranes in micro- and nanoelectromechanical systems (MEMS and NEMS). However, the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges, including collapse and rupture of the graphene. We have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on membranes with high yields. We have demonstrated the manufacture of square graphene membranes with side lengths from 7 µm to 110 µm, and suspended proof masses consisting of solid silicon cubes that are from 5 µm × 5 µm × 16.4 µm to 100 µm × 100 µm × 16.4 µm in size. Our approach is compatible with wafer-scale MEMS and semiconductor manufacturing technologies, and the manufacturing yields of the graphene membranes with suspended proof masses were >90%, with >70% of the graphene membranes having >90% graphene area without visible defects. The measured resonance frequencies of the realized structures ranged from tens to hundreds of kHz, with quality factors ranging from 63 to 148. The graphene membranes with suspended proof masses were extremely robust, and were able to withstand indentation forces from an atomic force microscope (AFM) tip of up to ~7000 nN. The proposed approach for the reliable and large-scale manufacture of graphene membranes with suspended proof masses will enable the development and study of innovative NEMS devices with new functionalities and improved performances. Researchers in Sweden have manufactured graphene membranes with attached silicon masses. Graphene is an extremely attractive material for membranes in micro and nanoelectromechanical systems (MEMS and NEMS). However, creating graphene membranes which can support the proof masses used in MEMS and NEMS has proven challenging. Now, a team led by Frank Niklaus at the KTH Royal Institute of Technology developed a technique to manufacture graphene membranes with suspended silicon masses attached. The new method can fabricate membranes ranging from 7 µm to 110 µm on each side, with suspended silicon blocks of up to 16.4 µm x 100 µm x 100 µm. The membranes can withstand forces of up to 7000 nN. The new approach opens the door to the use of graphene membranes in MEMS and NEMS devices, with applications from nanoscale robotics to wearable electronics.  However, the application of suspended graphene in NEMS devices has thus far been limited to resonators19, pressure sensors25, switches28, loudspeakers29, microphones31 and devices for fundamental studies of the material and structural properties of graphene37. The reported suspended graphene structures include doubly clamped graphene beams, fully clamped graphene drums and suspended graphene-based cantilevers. Suspended structures are typically realized by transferring graphene from the original substrate to a prefabricated substrate with trenches15, cavities20 or membranes made of dielectric layers39 or by transferring graphene from the original substrate to a flat silicon dioxide (SiO2)42 or polymer substrate surface44 and then removing parts of the material underneath the graphene by sacrificial etching.The atomically thin structure of graphene (atom-layer distance of ~0.335 nm) and its remarkable mechanical7 to ~1010 µm3 in size) that are suspended on springs in the form of membranes, beams or cantilevers. Graphene, as a robust and intrinsically nanoscale material, could be used to suspend large proof masses, thereby forming spring-mass systems consisting of atomically thin graphene springs for potential applications as ultra-miniaturized transducer elements in future high-performance NEMS devices20. However, the realization of suspended graphene with large attached proof masses is difficult, and to the best of our knowledge, no such examples have been reported in the literature. A previous report of suspended graphene membranes with very small masses included micrometre-sized few-layer graphene cantilevers with diamond allotrope carbon masses  fabricated using focused ion beam (FIB) deposition for the study of the mechanical properties of graphene45. Previous literature also reports a spiral spring, a kirigami pyramid and a variety of cantilevers based on a suspended graphene monolayer supporting 50 -nm thick gold masses attached to suspended cantilevers46. However, these structures had to be kept in a liquid to maintain their mechanical integrity. Suspended graphene membranes with diameters of 3–10 µm, that were circularly clamped by a polymer (SU-8) and that supported a mass made of either SU-8 or gold located at the centre of the membrane, were reported for shock detection caused by ultra-high mechanical impacts47. However, all previous reports involved extremely small masses, and the fabrication methods employed, such as FIB-induced deposition, were slow and typically not compatible with large-scale manufacturing.In contrast to previously reported graphene membranes and beams, MEMS and NEMS devices such as accelerometers, gyroscopes and resonators often employ larger proof masses  proof masses that is compatible with MEMS and NEMS manufacturing processes and that can be utilized for devising NEMS with graphene membranes as structural and functional components. Our approach employs a silicon-on-insulator (SOI) substrate to form silicon proof masses that are etched in the silicon device layer of the SOI wafer. The graphene membranes are formed by transferring a double layer of CVD graphene to the pre-patterned SOI wafer, followed by a combination of dry etching and vapour HF etching of the buried oxide (BOX) layer to release the silicon proof masses and suspend them on the graphene membranes. Static and dynamic mechanical characterization of the manufactured structures shows that they are robust and can potentially be used as spring-mass systems in future ultra-small NEMS, such as resonators and accelerometers.To demonstrate the feasibility of graphene membranes with large suspended proof masses, we fabricated square membranes with different dimensions made of double-layer graphene on which silicon proof masses of different sizes were suspended. A typical device structure is illustrated in Fig. 2 layer  in the Raman spectra indicates the relatively high quality of the graphene. The shape of the 2D band in Fig. 53. For double-layer and multi-layer graphene, the 2D band becomes much broader, as shown in Fig. 53.To verify that double-layer graphene indeed exists in our fabricated structures, we performed Raman spectroscopy. Figure −1 Fig.  and the  −1 Fig. 51,52 dem−5 mbar actively pumped vacuum) by measuring the amplitude of their thermomechanical noise using laser Doppler vibrometry (LDV)  Fig.  that havDV) Fig. . The resDV) Fig. , ~90 kHzDV) Fig. , ~78.8 kDV) Fig. , and ~60DV) Fig. . As expeDV) Fig. . The corDV) Fig.  is estimDV) Fig. . The Q-fTo further confirm the frequency response of the spring-mass system of our structures, we used LDV to measure the frequency response of a device with a trench width of 3 µm and proof mass dimensions of 50 µm × 50 µm × 16.4 µm in air (atmospheric pressure) at room temperature by driving the device with a piezoshaker Fig.  was esti59  and characterizing the resulting structures by SEM. We fabricated twelve chips that comprised 672 structures in different batches, and we obtained similar yields for all chips. Figures 60. During graphene transfer, we used PMMA as a support layer for the graphene, as this allowed easy handling and transfer of the graphene. Even after thorough rinsing with organic solvents such as acetone, PMMA residues (long-chain molecules) remain adhered to the graphene due to the strong dipole interactions between PMMA and chemical groups on graphene60. To remove as many of the PMMA residues as possible, we selected some sample chips with released proof masses for annealing at 350 °C for 2 h. During the annealing process, the temperature was first steadily increased from 100 °C to 350 °C in 1 h and then decreased from 350 °C to 100 °C in 1 h. The surface of the graphene after annealing was cleaner  increased the probability of the masses being detached from the suspended graphene membranes due to capillary forces. Only employing HF vapour to etch the BOX layer required a very long time and increased the risks associated with overetching of the BOX layer. To increase the yields as well as the quality and efficiency of the fabrication process, dry etching followed by vapour HF etching was the preferred approach here.We experimented with several different process flows to fabricate graphene membranes with suspended proof masses and found that wet HF etching was hard to control and often caused graphene displacement, wrinkles or collapse of the graphene due to etching of the SiOWe also evaluated the possibility of transferring monolayer graphene over the trenches using our baseline process Fig. . HoweverIn summary, in this paper, we have reported a robust route to transfer and integrate double-layer graphene membranes onto a silicon substrate. The proposed manufacturing process is based on SOI wafer technology and allows the suspension of large silicon proof masses on graphene membranes. Our approach is scalable and highly compatible with silicon NEMS technology, and complementary metal oxide semiconductor (CMOS) wafers for the integration of NEMS devices with electronic circuits. The ability of the graphene membranes to withstand AFM indentation forces of up to ~7000 nN without failure indicates that the structures are very robust. Thus, the ability to realize graphene membranes with suspended large proof masses offers interesting opportunities for ultra-miniaturized graphene NEMS devices such as accelerometers, gyroscopes and resonators, with exciting applications in nanoscale robotics, autonomous vehicles, wearable as well as consumer electronics and the internet of things (IoT).2 layer on both sides of the wafer  was used to etch the SiO2 layer  , where the copper foil floated on the FeCl3 solution with the graphene side facing away from the liquid. Then, with the help of a silicon-carrier wafer, the PMMA/graphene stack without copper  were used. A standard wet transfer approach was employedher Fig. . The resher Fig. . Then, aher Fig. . Then, c W) Fig. . For wetper Fig.  was firsfer Fig. . The PMMfer Fig.  and subsing Fig. . A layering Fig.  using pring Fig.  and to ting Fig. . The SOIes Figs. , 2c1–c5.2)  from exposing and destroying the graphene, all four sides of the chip were sealed by Kapton tape. Then, an RIE etching process was employed to etch the main part of the BOX layer  Fig. , while m2) Fig. . To prevyer Fig. . To avoitup Fig.  was tempnes Fig. . Despite−5 mbar actively pumped vacuum) and the amplitude of structures that were driven by a piezoshaker in air (atmosphere pressure).Optical microscopy and SEM imaging were used to observe and characterize the morphology of the devices during and after device fabrication. Raman spectroscopy  was used to verify the presence and quality of the double-layer graphene of the manufactured devices. For static mechanical characterization, an AFM  with a cantilever (Olympus AC240TM) and an AFM tip (tip radius = 15 nm) was used to load defined forces at the centre of a proof mass on a graphene membrane to measure the force vs. proof mass displacement and the maximum force that the suspended graphene membrane can withstand without rupture. The spring constant of the AFM cantilever was calibrated to be 5.303 N/m. To measure the resonance frequency and quality factor of the structures, we used an LDV (Polytec UHF-120) with a laser spot size on the order of 2.5 µm to detect the amplitude of the thermomechanical noise of the structures in vacuum (~10Supporting Information


Furthermore, the GaN microrod LED arrays were transferred onto Cu foil by using the chemical lift-off method. Even after being transferred onto the flexible Cu foil substrate, the microrod LEDs exhibited strong emission of visible blue light. The proposed method to enable the dimension- and position-controlled growth of GaN microstructures on graphene films can likely be used to fabricate other high-quality flexible inorganic semiconductor devices such as micro-LED displays with an ultrahigh resolution.This paper describes the fabrication process and characteristics of dimension- and position-controlled gallium nitride (GaN) microstructure arrays grown on graphene films and their quantum structures for use in flexible light-emitting device applications. The characteristics of dimension- and position-controlled growth, which is crucial to fabricate high-performance electronic and optoelectronic devices, were investigated using scanning and transmission electron microscopes and power-dependent photoluminescence spectroscopy measurements. Among the GaN microstructures, GaN microrods exhibited excellent photoluminescence characteristics including room-temperature stimulated emission, which is especially useful for optoelectronic device applications. As one of the device applications of the position-controlled GaN microrod arrays, we fabricated light-emitting diodes (LEDs) by heteroepitaxially growing In In such heterostructures, the GaN microstructures provides a light-emitting active region through radiative recombination, which is significant in fabricating light-emitting devices and displays10. Moreover, when combined with a graphene film substrate, GaN microstructures demonstrate excellent tolerance against mechanical deformation12. Although GaN hybrid-dimensional heterostructures can be applied to prepare several types of flexible devices, the most promising device application pertains to a flexible high-resolution display with a micrometer-sized light-emitting diode (micro-LED) array14. For such applications, the dimensions and positions of the GaN microstructures must be precisely controlled for the individual operation of each micro-LED in the array. Nevertheless, the key criteria for optimizing the device performance, such as the morphology and position control, n- and p-type doping, and formation of quantum structures in the GaN microstructures, have not been extensively studied15. In this study, we realized the dimension- and position-controlled growth of GaN microstructures on graphene films and the formation of their heterostructures with InxGa1−xN/GaN multiple-quantum-well structures for use in flexible micro-LED applications. The precisely controlled growth of GaN microstructure on graphene films can help develop templates for the individual operation of the devices for micro-LED displays.Recently, hybrid-dimensional heterostructures consisting of GaN microstructures with two-dimensional (2D) graphene films have attracted attention for use in transferable and flexible electronic and photonic devices2) layer. To control the positions of the microstructures in the array, a patterned SiO2 growth mask layer with microhole arrays having a diameter and interdistance of 1 µm and 8 µm, respectively, was fabricated on the graphene film, and the microstructures were grown only on the patterned microhole sites. Subsequently, we grew a 0.5-µm-thick ZnO seed layer before the growth of GaN microstructure arrays to enhance the nucleation. The complete ZnO seed layer was deposited on each microhole pattern array  and fast Fourier transform (FFT) techniques. Figure 2); Si and O could be attributed to the SiO2 layer. The higher Ga concentration with respect to N concentration could be attributed to the focused ion beam sample preparation using a Ga ion source.The energy-dispersive X-ray spectroscopy (EDS) maps of the interface between GaN and graphene clearly demonstrated the chemical composition of GaN microstructures grown on graphene. Figure 2. At excitation densities below 350 kW/cm2, a wide emission peak at 367 nm was captured without any remarkable feature shown in Fig. 2, sharp peaks appeared at 367.4, 370.2, 372.9, and 375.8 nm with a regular spacing of 2.8 nm around the near-band-edge emission, which eventually emerged as the dominant feature in the PL spectra. Each waveguide mode underwent Fabry–Perot (FP) oscillations, thereby generating a number of resonance peaks in the lasing spectrum20. The FP resonance of the mode spacing was defined as ∆λ = λ2/2L[1/(n-λdn/dλ)], where ∆λ is the mode spacing, L is the cavity length, n is the effective refractive index, and dn/dλ is the first-order dispersion of the effective refractive index21. ∆λ was calculated to be 2.83 nm, which was consistent with the measured ∆λ. The observation of the lasing characteristics with a low threshold pumping density indicated that the GaN microrods grown on graphene had a high optical quality. It was considered that the GaN microrods having flat side facets, which were naturally grown without etching, enhanced the lasing properties by lowering the diffraction loss.Furthermore, the optical quality of the GaN microstructures grown on graphene was examined using power-dependent micro-photoluminescence (μ-PL) spectroscopy. For the optical characterizations, we used the hexagonal arrays of GaN microrods with a diameter of 3.9 ± 0.2 μm and height of 15.8 ± 0.4 μm  was spin-coated on the heterostructures, and a buffered oxide etchant was used to etch the sacrificial SiO2 from the 300-nm-thick SiO2/Si substrate. The device structure was transferred onto a flexible substrate. The coaxial microrod heterostructures could tolerate the ultimate bending conditions due to the micrometer-sized spacing of the micro-LED arrays. The GaN micro-LEDs were wrapped around a 1-mm-diameter paper clip to test the effect of mechanical deformation, as shown in Fig. The fabrication process of flexible LEDs is illustrated in Fig. p-GaN, InxGa1-xN/GaN MQWs, and n-GaN on CVD graphene films. To fabricate flexible micro-LEDs, thin Ni/Au layers (10/10 nm) were deposited on the surface of coaxial p-GaN microrods. The micro-LEDs on the graphene films were lifted from the sacrificial substrate and easily transferred onto the Cu foil. Subsequently, the flexible LEDs were transferred onto the Cu foil substrate to form an electrode. The current was injected directly through the graphene, thereby generating a vertical structure for the microstructure LEDs.The flexible LEDs on graphene films were fabricated using the coaxial microrod heterostructures consisting of 2 LED devices captured strong blue light emission at applied biases ranging from 0.5 to 2.0 mA. The intensity of emitted light was very strong as visibly seen. It was able to brighten up the room. Figure xGa1−xN MQWs embedded in the LEDs. The EL spectra also showed longer wavelength tail next to the 421 nm peak and a small peak near 550 nm. We believe that the longer wavelength EL emissions are related to the variable composition and thickness of InxGa1-xN/GaN MQWs coated on different facets of GaN microrods which is typically observed in other multifacetted GaN nanostructured LEDs27. In addition, the current–voltage (I–V) characteristic curve of the LED, as shown in Fig. −4 A at –3 V, indicating the formation of a p–n junction LED.We investigated the light-emitting characteristics of the microstructure LEDs through electroluminescence (EL) spectroscopy. As shown in Fig. xGa1−xN/GaN coaxial quantum nanostructures on graphene films, which exhibited strong blue emission; moreover, the diodes exhibited rectifying behavior. The combination of dimension- and position-controlled GaN quantum nanostructures and 2D graphene films can facilitate the realization of other types of flexible device applications with multi-functional characteristics and novel physical properties.We realized the dimension- and position-controlled growth of GaN micro-LEDs on graphene films by using a ZnO seed layer. The use of a ZnO seed layer helped to enhance the nucleation of GaN on graphene and ensured the formation of GaN microrod arrays. The GaN micro-LEDs had a high crystalline structure and high optical quality, as determined by TEM, PL, and EL measurements. Using the dimension- and position-controlled microstructures, micro-LEDs including diverse quantum nanostructures were fabricated on graphene films, leading to the development of high-resolution three-dimensional micro-LEDs and micro devices on graphene films. In particular, we fabricated flexible GaN/InSupplementary Figures.


After the continued failure of β‐secretase (BACE1) inhibitor clinical trials in prodromal as well as mild‐to‐moderate Alzheimer's disease (AD), they are shifting to further earlier or asymptomatic stages. The aim of this study is to explore a cognitive paradigm that allows us to more sensitively detect beneficial effects of BACE1 inhibitors in presymptomatic AD.GRL‐8234 , a small‐molecule BACE1 inhibitor, was administered once daily for 28 days to the 5XAFD transgenic mouse model of AD. The contextual fear conditioning was used to evaluate the effects of GRL‐8234 on memory deficits in 5XFAD mice at different ages.Chronic administration of GRL‐8234 to 5XFAD mice rescued their contextual memory deficits, when tested 1 day after training at 6‐8 months but not at 12 months of age. Importantly, 4‐month‐old 5XFAD mice retain the ability to form contextual memory equivalent to wild‐type controls, demonstrating that the standard method of 1‐day memory assessment is not suitable for evaluating BACE1 inhibitor efficacy in ameliorating cognitive declines during earlier disease stages. Despite normal contextual memory formation, young 5XFAD mice showed faster forgetting when a longer delay (28 days) intervened between training and memory testing. Notably, GRL‐8234 administered to 4‐month‐old 5XFAD mice during the 28‐day delay reversed accelerated long‐term forgetting almost completely back to wild‐type control levels.The results provide experimental evidence that accelerated long‐term forgetting represents more sensitive memory testing that can help evaluate BACE1 inhibitor therapy in presymptomatic AD populations. Despite intact 1‐day contextual memory, 4‐month‐old 5XFAD mice showed faster forgetting when a longer delay (28 days) intervened between training and memory testing. Notably, accelerated long‐term forgetting was reversed by the BACE1 inhibitor GRL‐8234 administered during the 28‐day delay. Therefore, accelerated long‐term forgetting represents a sensitive paradigm that can detect subtle cognitive decline and help evaluate early BACE1 interventions during presymptomatic stages of Alzheimer's disease. Data were presented as mean ± SEM, and the level of significance was set at 33.1P < .05). GRL‐8234 significantly increased contextual freezing in 5XFAD mice at 6‐8 months of age (P < .05), restoring the impaired 1‐day memory completely back to wild‐type levels  at ~ 6 months concomitant with moderate Aβ accumulation and the onset of Schaffer collateral‐CA1 synaptic dysfunction.s Figure . In conts Figure . Togethe3.2P < .05), while GRL‐8234 administered during the 28‐day delay reversed accelerated long‐term forgetting in 5XFAD mice almost completely back to wild‐type control levels (P < .05)  Figure . The res4Consistent with our previous findings in the spontaneous alternation Y‐maze task,More importantly, the standard procedure of 1‐day memory assessment was not sensitive enough for detecting subtle declines in the contextual fear conditioning in 4‐month‐old 5XFAD mice, while a longer delay (28 days) intervening between training and memory testing revealed accelerated long‐term forgetting that was reversible with chronic administration of GRL‐8234. Consistent with our findings in young 5XFAD mice,−/− knockouts.+/– reduction or the lower dose of inhibitors devoid of synaptic side effect.A growing number of BACE1 substrates besides APP uncover new physiological roles of this protease,The author declares no conflict of interest.MO designed the research, performed the experiments, analyzed the data, and wrote the manuscript.All animal experiments were approved by the Animal Care and Use Committee of Nathan Kline Institute.Table S1Click here for additional data file.


During the 2020 SARS-CoV-2 pandemic, physical distancing and mask use guidelines were implemented resulting in a decline in the number of infections caused by influenza, respiratory syncytial virus and otitis media. A surveillance analysis from England and Taiwan showed a decline in invasive pneumococcal disease (IPD) . We hypothesized that COVID mitigation efforts resulted in a decrease in incidence of pediatric IPD within the U.S. during 2020 compared to previous years.Streptococcus pneumoniae from normally sterile sites . Pneumococcal pneumonia was defined as an abnormal chest radiograph in the presence of a positive blood, pleural fluid or lung culture. Mastoiditis was identified by positive middle ear, subperiosteal abscess or mastoid bone culture. Serotypes were determined by the capsular swelling method. Hospital admission numbers were obtained for incidence calculations. Statistical analyses were performed using STATA11. A p< 0.05 was considered significant.We reviewed all cases of IPD among 7 children’s hospitals from the U.S. Pediatric Multicenter Pneumococcal Surveillance Group from 2017-2020. IPD was defined by the isolation of A total of 410 IPD cases were identified. The cumulative incidence of IPD (0-22 years of age) decreased from 99.2/100,000 admissions in 2017-2019 to 53.8/100,000 admissions in 2020 . Pneumococcal bacteremia and pneumonia decreased significantly in 2020 (p< 0.05), and although not statistically significant, there were fewer cases of meningitis and mastoiditis when compared to previous years (p=0.08) . Sex, race, age or presence of comorbidities were not significantly different between groups. Most common serotypes in 2020 were 35B, 3 and 15B/C .S. pneumoniae via droplets and viral infections frequently preceding IPD. These precautions might be useful in the future to decrease IPD, especially in high-risk patients.The observed decline in IPD cases during the first year of the SARS-CoV-2 pandemic is likely associated with mask use and physical distancing limiting transmission of Sheldon L. Kaplan, MD, Pfizer (Research Grant or Support) Tina Q. Tan, MD, GSK  Involved: Self): Advisor or Review Panel member, Grant/Research Support; ILiAD  Involved: Self): Advisor or Review Panel member; Merck  Involved: Self): Advisor or Review Panel member, Grant/Research Support; Moderna  Involved: Self): Advisor or Review Panel member; Pfizer  Involved: Self): Advisor or Review Panel member Pia S. Pannaraj, MD, MPH, Pfizer (Grant/Research Support)Sanofi-Pasteur (Advisor or Review Panel member)Seqirus (Advisor or Review Panel member) Larry Givner, MD, AstraZeneca (Advisor or Review Panel member) Kristina G. Hulten, PhD, Pfizer (Research Grant or Support)


X-ray photoelectron spectroscopy analysis confirmed that the graphene precursors, as well as the coatings, contained typical nitrogen groups, such as pyridinic and pyrrolic, and sulfur groups, such as thiol, thiophene, or C-SO2. However, due to oxidation during deposition, the qualitative and quantitative composition of the graphene coatings changed relative to the composition of the precursors. In particular, the concentration of nitrogen and sulfur dropped and some thiophene groups were oxidized to C-SO2. Studies showed the functionalized coatings had a uniform, defect-free, hydrophobic, more adhesive surface than nonmodified films. The corrosion measurements demonstrated that these coatings had better protective properties than the ones without these heteroatoms. This behavior can be assigned to the catalytic activity of nitrogen towards oxidation of C-SO2 groups to C-SO3H with oxygen.Electrophoretic production of anticorrosion carbonaceous coatings on copper could be successfully performed by anodic oxidation of negatively charged graphene platelets suspended in an aqueous solution. The various platelets were synthesized by Hummer’s method followed by a hydrothermal reduction in the presence of NH Nevertheless, the coatings probably contain a number of intact graphene domains, which might be current conductive. One can visualize such coatings as the one composed of three domains: pure graphene (current-conducting), oxidized graphene , and defects or holes that do not protect the metal surface. Once graphene oxide is employed as the EPD precursor, we end up with coatings that do not meet the criteria of good protective properties [2 to SO3 over N-doped graphene [2 to C-SO3H with oxygen (from the air) penetrating the N-doped graphene coatings. As a matter of fact, this reaction also involves oxygen reduction, but the electrons are donated by sulfur not metal, thus it may diminish corrosion.Graphene and its various oxidized or chemically functionalized forms have been recently studied as monolayers or multicomponent coatings for corrosion protection of metals. Graphene possesses properties that are beneficial for metal protection, such as chemical resistance, mechanical endurance, good adhesion to metals, or impermeability to gases and water. On the other hand, the conducting graphene layers might accelerate the corrosion in some instances . Moreoveposition . This isoperties ,11,12. Toperties . In turnoperties . Howeveroperties , which toperties . Indeed,graphene ,18. We hNitrogen- and sulfur-functionalized reduced graphene oxide coatings as the anti-corrosion layer have not been reported yet. In the present work, graphene oxide, reduced graphene oxide, and nitrogen- and sulfur-functionalized reduced graphene oxide were synthesized by an improved Hummer’s method, one-step hydrothermal method, and one-step hydrothermal method in presence of ammonium thiocyanate, respectively. Subsequently, the obtained products were electrophoretically deposited on the copper substrate and subjected to numerous studies, revealing their properties.4, purity: 99.0%, POCH, Gliwice, Poland), orthophosphoric acid , sulfuric acid , hydrogen peroxide , ethanol , hydrochloric acid , acetone ((CH3)2CO, POCH), ammonium thiocyanate , and sodium chloride  were used. Copper sheets , graphite powder , potassium permanganate . At the end, the precipitate was washed with acetone, which was then evaporated, leaving around 1 g of a brown solid.Graphene oxide was synthesized by the improved Hummer’s method . ConcentThe one-step hydrothermal method was used for the preparation of reduced graphene oxide . In tota4SCN  were dispersed in 40 mL of distilled water by using an ultrasonic bath for 30 min. Then, the mixture was put into a stainless steel autoclave heated to 180 °C for 6 h. Afterwards, the solid was filtered under vacuum, washed several times with distilled water, and dried at 60 °C for 24 h.Nitrogen- and sulfur-functionalized reduced graphene oxides  were prepared by the one-step hydrothermal method in the presence of ammonium thiocyanate . GO  analysis was performed with Rigaku MiniFlex 600 in the range of angle 2°–90° . Characteristic crystallographic parameters such as an interlayer distance (d002), an in-plane crystallite size (aL), and an average crystallite width (cL) were calculated using the following equations: λ—radiation wavelength (Å); θ1—(0 0 2) diffraction peak position (°);θ2—(1 0 0) diffraction peak position (°); FWHM—width at half height of the corresponding diffraction peak (rad).All functionalized precursors of coatings were prepared from newly synthesized graphene oxide. Results for GO and rGO are meant to be reference data. Fourier Transform Infrared Spectroscopy (FTIR) of precursors of the coatings was conducted on the spectroscope PerkinElmer Frontier over a scanning range 550–4000 cmD/IG was calculated as the quotient area under the D peak and under the G peak. As a result of the deconvolution of bands, the area under peaks was obtained. X-ray photoelectron spectroscopy (XPS) analysis was prepared by the Omicron NanoTechnology system at a pressure below 1.1 × 10−8 mBa and at room temperature. The Argus hemispherical spectrometer with a 128-channel collector was used for the energy measurement of photoelectrons. The photoelectrons were excited by a Mg-Kα X-ray source operated at 15 keV and 300 W. Analysis of obtained results was performed using CASA XPS software package with Shirley background subtraction and least-square Gaussian–Lorentzian—GL(30) curve fitting algorithm. Calibration of measured spectra to the binding energy of 285 eV for the C1s line was conducted. Zeta potential measurements of the graphene sheets in aqueous suspensions were carried out by using Malvern Zeta-Sizer. A contact angle of the coatings was determined by the goniometer Cam 200 KSV. The used liquid was distilled water (dosing volume of water of 1 µL). The surface topography of layers was defined by the Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). SEM images before the electrochemical tests were collected on the microscope Quanta FEG 400-FEI Company , whereas SEM images after electrochemical tests and thickness of the coatings were obtained by SEM Microscope FEI Quanta FEG 250 with a SE-ETD detector (secondary electron—Everhart-Thornley detector), using 10 kV beam accelerating voltage. Film thickness is the average value of all thickness measurements of the layers. AFM images were obtained using Bruker Catalyst by noncontact mode using Au coated silicon tips (scan rate—0.273 Hz). The cross-cut test was used to determine adhesion between the graphene coating and the metal substrate. With a knife, cuts separated by about 1 mm were made on the surface of coatings. After an adhesive tape was broken, on the basis of the number of detached graphene flakes, the adhesion of coatings was determined.Raman spectra were recorded on Horiba-Jobin Yvon microprobe apparatus excited by a 532 nm laser. A ratio of I−1. To stabilize potential, every sample was immersed in the solution for 30 min before measurement.A sodium chloride solution (3.5% NaCl) was used as the corrosive medium. Chloride ions are very aggressive for the copper substrate; therefore, it is important to assess the durability of the coatings in this environment. For evaluation of the protective properties of the graphene coatings, a potentiodynamic polarization was applied. Measurements were carried out by using a potentiostat, ATLAS-SOLLICH 0531 (Poland), connected to a cell containing the coated copper substrate as a working electrode, an Ag/AgCl (KCl saturated) reference electrode, and a platinum wire as a counter electrode. Electrochemical tests were performed twice for each sample, in a potential range of −0.1 to 0.1 V  with a scan rate of 0.5 mV scorrE) and corrosion current density (corrI) were determined from the intersection of the anode and cathode curves. Corrosion rate (CR) was calculated from the following equation (ASTM G59):K—corrosion rate constant (mm year−1);corrI—corrosion current density (µA cm−2);EW—equivalent weight, for Cu 31.7 g;d—density, dCu = 8.97 g cm−3.Corrosion potential . The stretching energy of 1500 cm−1 is completely missing for GO , the strong band at 1500 cm−1 shows up  was estimated from the width of (1 0 0) reflections at ca. 43°, while the stacking number of graphene sheets (Lc) was estimated from the width of (0 0 2) peaks at ca. 26°  [The elemental compositions of the studied graphene precursors and coatings were studied by the XPS technique . The higx = 2,3) . 2 hybridization of the carbon atoms . During electroformation of the coatings, many thiophene and thiols were oxidized to carbon bound –SO2 groups, although some sulfur was lost due to SO2 gas release.The percentage chemical compositions of the precursors and coatings are presented in Electrophoretic deposition requires stable dispersions. Due to the large interlayer distance for graphene oxide maintained by weak interactions, the stable suspension of graphene oxide was easily produced by 0.5 h treatment in an ultrasonic bath. Reduced graphene oxide samples were characterized by significantly lower interlayer spacings and thus, stronger interactions between layers. This caused the obtention of uniform suspension more difficult, simultaneously contributing to prolonged ultrasonic treatment (around 2 h). The obtained suspensions were stable due to the Zeta potential (ζ) being lower than −30 mV . Measure2 groups. Moreover, an increase in the potential from N,S-rGO300 to N,S-rGO600 samples results from the increasing content of graphitic nitrogen , whose positive charge compensates the negative charge of C-SO2 groups.As expected, the Zeta potential for rGO is higher (less negative) than that for GO. However, in the case of functionalized graphene oxide samples, the Zeta potential is much lower than that for GO and rGO due to the presence of the C-SO2 release during electrolysis. The other precursors were not subjected to the destructive CO2 evolution because they contained a substantially lower concentration of oxygen in their structures. The same observation is also true for the functionalized coatings. The roughness of the coatings was estimated by the AFM . The resThe low wettability of the protective coatings is a crucial property to fend off water. The measured contact angles show  that allSEM images of all coatings, before and after electrochemical studies, are presented in The corrosion resistance of all coating against 3.5% sodium chloride solution was tested by a potentiodynamic polarization method. The results are presented by the Tafel plots in corrE shifted towards more positive values for all coated samples, indicating that coatings probably act as a barrier separating copper from the aggressive environment. However, the hydrophilic nature of the graphene oxide allows penetration of the GO coatings by water, causing oxidation of copper. Moreover, the high current density stems also from the partial or complete oxidation of carbon, which may finally result in the decomposition of the coatings.As can be seen in In the case of the rGO coatings, their hydrophobicity makes them an impenetrable water barrier. Therefore, the measured corrosion current stemmed only from the oxidation of carbon. Thanks to this, the surface of these coatings became smoother after the electrochemical tests.2 groups formed as a result of the oxidation of thiophene groups during EPD. Nitrogen that is also present in the structure can effectively catalyze the oxidation of these groups to C-SO3H by oxygen from the air, so oxygen can no longer depolarize the copper metal. The corrosion protection mechanism of the graphene coatings is presented in In our previous work, we showed that the nitrogen-functionalized graphene oxide coatings had protective properties, but these were comparable to the anticorrosion properties of the reduced graphene oxide coatings. Nitrogen groups exhibiting catalytic properties towards the oxygen reduction reaction were responsible for this behavior. The coatings produced in this study contain a substantial amount of C-SO2 groups in their structures, which formed as a result of the oxidation of thiophene groups. Nitrogen can effectively catalyze the oxidation of these groups to C-SO3H with oxygen from the air. The introduction of nitrogen and sulfur groups to the graphene oxide structure contributed to the improved corrosion resistance of graphene coatings produced by EPD on the copper substrate. These coatings had numerous C-SO


Blended cognitive-behavioural therapy (bCBT) combines face-to-face CBT (FtFCBT) and Internet-based CBT (iCBT) into one integrated treatment protocol, opening up new ways to deliver therapy, increase cost-effectiveness and resolve scarcity of therapist availability. When traditional therapy is transformed into a new format, there is a need to evaluate whether principles of the new protocol are consistently applied.N = 44) received bCBT within a randomised controlled trial. Ratio of FtF to online sessions, session frequency and therapist adherence to instructions were assessed.This study aimed to explore therapist fidelity to bCBT protocols for anxiety disorders in specialised mental health care and to assess whether fidelity is related to patient characteristics. Adult patients , as well as patient computer experience . Adherence to instructions in FtF sessions was based on a subset of patients (n = 23) and should therefore be interpreted with caution.Overall therapist fidelity with regard to ratio of blending, session frequency and instructions was high. Correlations were found between patients' share of online sessions and both session frequency (The blended approach was generally delivered as intended, indicating that the format is feasible in specialised mental health. •Therapist fidelity to blended cognitive behavioural therapy protocols for severe anxiety disorders was high.•Treatment of higher intensity had a higher share of online sessions.•Patients with more computer experience were likely to receive higher shares of online sessions.•Results support feasibility of the blended approach in specialised mental health care.•Results enhance confidence in earlier findings on effectiveness and cost-effectiveness of blended cognitive behavioural therapy for severe anxiety disorders. Patients in both groups reported high levels of treatment satisfaction, and both conditions yielded large within group effect sizes at posttest and at one-year follow-up. A small RCT (N = 36) of bCBT for panic disorders by another research group achieved results in line with our findings regarding acceptability and effectiveness, with medium to high effect sizes in both treatment groups and no differences in treatment satisfaction between the groups  is an effective psychological treatment for anxiety disorders . Internee groups .Blended interventions appear increasingly popular as treatment protocols for blended therapy become more widely available . HoweverN = 36) pointed to a lack of clear guidelines on incorporating online sessions as a major barrier to providing bCBT.The degree of treatment fidelity is important not only for understanding effectiveness and cost outcomes, but it also provides essential input for developing therapist guidelines on how to use bCBT . In a reN = 495) (N = 39)  were rated in terms of therapist adherence to the CBT protocol, with mean scores emerging of 85% on a 0%-to-100% scale (SD = 10.4) and 6.18 (SD = 0.51) on a 1-to-7 scale. Concerning Internet-based CBT, Hadjistavropoulos and colleagues investigated adherence to feedback instructions in online feedback messages   or videomessages . They ramessages  therapisn = 250) trained and equipped to use bCBT actually offered a treatment containing both FtFCBT and iCBT to their patients. Furthermore, they used iCBT as an add-on rather than a replacement of FtF sessions. In a qualitative study on barriers and facilitators of bCBT  therapists (n = 5) stated that they lacked knowledge on how to integrate online components in FtF therapy and in a study on patient experiences with bCBT (n = 15), a deficiency in the interplay between FtF and online components and a lack of therapist awareness of patient activities in online sessions was found to be a cause of patient dissatisfaction  or FtFCBT (n = 62) in one of four Dutch outpatient clinics for specialised mental health care between November 2015 and July 2017. Written informed consent was obtained from all participants before baseline assessment and randomisation. Participants were informed that participation in the trial was not contingent upon agreeing to be audio-recorded. A separate consent document for permission to record was obtained. A total of 45 patients started the bCBT treatment. Since one patient dropped out after the first session, our study of treatment fidelity analyses data from the 44 participants who actually received bCBT. The trial was approved by the Medical Ethics Committee of the Amsterdam University Medical Centers, location VU University Medical Center (registration number 2015.073) and registered in the Netherlands Trial Register (NTR4912).Data were collected within an RCT assessing the clinical and cost-effectiveness of bCBT in comparison with FtFCBT . In that2.2www.minddistrict.com). Patients and therapists accessed this platform with a personalised login. The online sessions offered information (videos and text), testimonials from fictional patients, assignments  and homework exercises . Therapists provided feedback on assignments and homework exercises. Default text templates for feedback and instructions were supplied for every online session as a therapist aid for providing feedback as intended. Therapists were free to tailore these texts to the specific needs of their clients. The online treatment platform also offered the option of repeating an online session. Therapists could decide on that if they deemed it beneficial, for example if the patient had not fully comprehended the content of an online session or had greatly benefited from a specific exercise in it.Separate manualised bCBT protocols were developed for patients with panic disorder, social anxiety disorder and generalised anxiety disorder . Their content was based on protocols for FtFCBT , which contain evidence-based elements for the treatment of anxiety disorders, such as cognitive therapy and exposure  see . In all 2.3Patients were invited for study participation if they (i) were aged 18 or older and (ii) met the DSM-IV criteria for panic disorder with or without agoraphobia, social anxiety disorder or generalised anxiety disorder, as diagnosed with the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I ) or the 2.4Therapists were trained and experienced in delivering CBT. Prior to treating patients in the trial, all therapists received a 2-h training course in the delivery of the blended treatment protocol, provided by researcher GR. During the training, therapists received instructions on how to apply the blended format, and were shown the main sections and functionalities of the online platform such as the start page of the therapist portal and entry point to other sections of the platform, treatment modules, homework area, feedback templates and messaging function. They also had the chance to practise with a fictitious patient. In addition, discussion sessions were organised by the research team in which therapists could exchange their experiences with bCBT.2.5Information on patient characteristics was obtained via an online self-report questionnaire at baseline. Primary diagnosis and comorbid disorders were established by a diagnostic interview .2.7The bCBT protocol prescribed weekly sessions. Session frequency was determined by dividing the total number of completed FtF and online sessions by the total therapy duration in weeks (session frequency = (number of completed FtF sessions + number of completed online sessions) / duration therapy in weeks)).2.8p < .001, 95% CI 0.86–0.93) and for online components 0.90 , indicating good agreement between the raters with respect to both FtF and online sessions.To assess fidelity to the blended protocol in the FtF sessions and the online sessions, we developed a checklist based on the treatment protocol, containing the mandatory blended protocol components  were used to describe the sample and the observed fidelity. The relationships between fidelity scores and patient characteristics were assessed with Pearson correlations. Analyses were undertaken using SPSS, version 23 .33.1A total of 44 patients were given bCBT by 28 therapists. Baseline demographics and clinical characteristics of the patient sample can be found in 3.2n = 29) contained 50% to 60% FtF sessions. In fourteen cases (32%), the share of FtF sessions was either 40% to 50%  or 60% to 70% ; in two cases (5%) it was higher than 70% (75% and 80%).The mean treatment duration was 12.6 sessions (SD: 5.2), with 6.7 FtF sessions (SD: 2.6) and 6.0 online sessions (SD: 2.9) in 15.6 weeks (SD: 8.7). The mean percentage of FtF sessions in the 44 courses of blended treatment (55%) was almost equal to the prescribed 53%. Most courses of treatment , slightly lower than the 1.0 sessions per week as prescribed. Five courses of treatment (11%) had a frequency of exactly 1 session per week, in 13 cases (30%) frequency was higher (range: 1.1–1.4) and in 26 cases (59%) frequency was lower (range: 0.3–0.9).r = 0.373, p = .013), suggesting that patients who received a larger share of online sessions were likely to have higher-frequency treatment than those receiving more FtF sessions.Session frequency was higher  when the ratio of online to FtF sessions was positive than when the ratio of FtF to online sessions was positive . The correlation between session frequency and the FtF-to-online ratio was significant , therapists forgetting to record sessions, poor recording quality and low battery of the recording device. Forty-six (62%) recorded sessions were conducted in full accordance with the blended instructions in the protocol, while in 28 sessions (38%) some devations to the protocol occurred  sessions received by 23 patients. There were no significant differences in baseline characteristics  between the patient sample that consented with recordings and the patient sample that did not consent with recordings. The recorded sessions were provided by 17 therapists, of whom 15 were female (88%), 10 (59%) were licensed health care psychologists and 7 (41%) were supervised psychologists in training for health care psychologists. Reasons for non-availability of recordings included: participants not consenting to be recorded , therapists deviated from the protocol where the previous online session should have been discussed (Boxes 2a and 2b). In one case the online session was not mentioned at all; in other cases therapists did refer to it, but there was little or no discussion of homework and assignments.n = 20). In the other two cases, therapists did not discuss the homework for the upcoming online session.Most deviations from the protocol occurred when the upcoming online session was to be discussed (Box 3). In 22 of 66 sessions (33%), therapists deviated from the instructions, mostly by not scheduling an appointment for providing feedback on the next online session  of the 257 online sessions were repeated. Feedback messages on repeated sessions were usually short and practical in nature (Boxes 5a to 5c) and usually did not contain CBT-specific feedback (31 of 34 messages).3.5r = −0.314, p = .038), indicating that the treatment of patients more experienced with computers was likely to contain a larger percentage of online sessions. No significant associations between other patient characteristics and fidelity outcomes were found.44.1The aim of this paper was to explore therapist fidelity to bCBT protocols for anxiety disorders in specialised mental health care, considering insights in the actual application of blended treatment are lacking. Additionally, we wanted to gauge the influence of patient characteristics on bCBT fidelity, since therapists believe some patients are better suited for bCBT than others .g by 0.45, with the total number of sessions held constant.Overall, therapist adherence to the instructions in the blended treatment protocol was high. The mean session frequency was 0.89 sessions per week (SD: 0.26), slightly lower than the 1.0 sessions per week as prescribed. The ratio of FtF to online sessions was negatively associated with session frequency, suggesting that a larger share of online sessions enables a higher treatment frequency. This may be relevant in the light of meta-analytic findings by Cuijpers and colleagues  showing Our inspection of patient characteristics showed a significant association between the ratio of blending and patient experience with the use of computers, indicating that those with more computer experience were more likely to receive a higher share of online sessions. Other patient characteristics, such as pretreatment anxiety severity or comorbidity, were not associated with fidelity outcomes. This finding is in line with previous findings for FtF therapy  and refu4.2Evaluating fidelity is a time-consuming process, and it becomes even more complex when two treatment modalities are integrated into one treatment protocol. For this reason, treatment fidelity is often not examined in intervention studies, and had not yet been evaluated for blended treatment at all, even though it is essential to the interpretation of treatment outcomes and to successful implementation of a blended format. As this study was an investigation of therapist fidelity to a blended treatment protocol assessing both the FtF and the online elements of the treatment, we were able to examine what actually happened during blended treatment: did it blend?It should be taken into account that the current analyses into fidelity were explorative in nature and should be seen as one of the first steps in unravelling the application of blended treatment. Although findings on blending ratio, session frequency and adherence to protocol instructions in online sessions were based on the full patient sample, results regarding the adherence to instructions in FtF sessions were based on a subsample of patients and a subset of therapy sessions. Even though characteristics of this subsample of patients resembled the full sample, we cannot be sure whether the recorded sessions were representative of all FtF sessions, which is a clear limitation of the study.Furthermore, comparing our results to other studies, and comparing outcomes on treatment fidelity in general, is complicated by the lack of uniformity in the definition of fidelity used by different authors. One general definition is: ‘the degree to which a treatment is implemented as it was intended in the original protocol’; however, more specified definitions vary across studies and varying interpretations of the concept hinder shared understanding of findings . The cur4.3Opportunities to improve therapist fidelity to the blended treatment format appear to lie in enhancing therapist recognition of FtF and online sessions as equally important elements of treatment. If that is not acknowledged, online sessions cannot adequately replace FtF sessions. In the current study, therapists often did not set a date to provide feedback on online sessions, which could be an indication that a therapist sees those sessions as merely supportive to the FtF sessions and this idea can uncounsiously be transferred to the patient. This requires attention in training therapist. Furthermore, if an appointment calendar function were added to the online platform, that might improve fidelity to this protocol component and heighten therapists' awareness of the importance of online elements in blended treatment.Previously, a lack of clear guidelines has been identified as a barrier to the use of bCBT . In someOne benefit of a blended format, as found in earlier studies, is that it can enhance therapists' adherence to the treatment protocol . In the Finally, an interesting topic for subsequent research would be whether therapist variables are associated with the degree of treatment fidelity. Identifying therapist characteristics that predict fidelity to bCBT could assist mental health care services in the selection and training of professionals.5Our findings suggest that the blended treatment was generally conducted as intended, indicating that delivery of bCBT in the applied format is feasible for therapists in specialised mental health care. This enhances confidence in the findings on effectiveness and cost-effectiveness of bCBT reported elsewhere : high trThe current study was conducted prior to the coronavirus crisis. The outbreak of a pandemic disease highlights the relevance of online treatment as an important element of routine care practice . BlendedProtocol components with instructions regarding the blended format.Supplementary Table 1Patient characteristics.Supplementary Table 2n = 74 recorded sessions).Adherence to protocol instructions in face-to-face sessions (Supplementary Table 3n = 257 sessions).Adherence to protocol instruction in online sessions .Correlations of patient characteristics with treatment fidelity outcomes (Supplementary Table 5Content of the sessions in the bCBT protocol.Appendix 1Checklist for fidelity to bCBT treatment protocol, including examples.Appendix 2Examples of full and partial adherence to blended instructions in FtF sessions and online feedback messagesAppendix 3The following are the supplementary data related to this article.The authors report no conflicts of interest related to this publication.


However, monolayer graphene still suffers from defects that cause leakage. Here, we report a method of sealing defects in graphene transferred onto porous polymer substrate via reduced graphene oxide (rGO). The influence of various reducing agents  on the properties of rGO was investigated by SEM, Raman, FTIR, and XRD. Subsequently, membranes based on graphene/reduced graphene oxide were tested in a forward osmosis system using sodium chloride (NaCl). The effect of the effectiveness of the reduction of graphene oxide, the type and number of attached groups, the change in the distance between the rGO flakes, and the structure of this material were examined in terms of filtration efficiency. As a result, semi-permeable centimetre-scale membranes with ion blocking efficiency of up to 90% and water flux of 20 mL h The rapid growth of the human population, industrialisation, and climate change have a great impact on decreasing water supplies. Along with the continuous release of pollutants into water such as microplastic, heavy metals, dyes, etc., these have caused over one billion people over the world to suffer from drinking water shortage . For thiThe desire to develop a membrane with the smallest possible thickness, and thus, to obtain the lowest flow resistance, has prompted researchers around the world to work on the use of graphene and related materials for this purpose. Apart from the thickness of one atom (the thinnest possible active part of the membrane), the main advantages of graphene are its strength, flexibility, chemical, and thermal properties. Graphene, in its ideal form, cannot be used as a filtration membrane because it is impermeable even to atoms as small as helium , and, th® can be listed. Quasi-monocrystalline HSMG® graphene is produced by the metallurgical method on a substrate of liquid copper [Among the methods of synthesis of large-area graphene methods like CVD on liquid copper, CVD on solid copper, and HSMGd copper ,12. The ®). Despite the development of the mentioned transfer methods, cracks and defects still appear at this stage and must be eliminated in the next steps of membrane production.The production efficiency of graphene membranes and their size are largely limited by the difficulty of obtaining large, continuous, and undefective graphene layers on mainly copper and nickel substrates. The synthesis of large-area graphene and its transfer to the support substrate determine the purity and quality of the produced membrane. Currently, the most used method of graphene transfer is a wet transfer, in which graphene is coated with a carrier polymer and then the graphene growth substrate is etched with appropriate reagents. A competitive method for wet transfer is electrochemical delamination, in which graphene is also coated with a carrier polymer, and then in the electrolyte, under the influence of the applied voltage, is separated from the substrate due to the hydrogen generated between the growth substrate and graphene ,14. It i® graphene sealed with reduced graphene oxide or nylon manufactured on polymer scaffoldings revealed semi-permeable properties in FO filtration mode. The clue of this solution was sub-nanometre pores in the graphene layer structure. The effectiveness of the graphene membrane depends on how it is sealed. Using graphene oxide for this purpose may be of key importance [Currently, RO and FO membranes based on various graphene materials are being developed and tested. The active layers of such membranes are for example graphene monolayers, graphene multilayers, graphene monolayers sealed with polymer materials, layers of graphene oxide, and reduced graphene oxide applied by various methods that determine the final properties of the membrane. The membranes produced in this way are tested in the FO system, aimed at determining the speed of water transport and the reverse diffusion of ions. Osmotic stands with different salt concentrations (draw solution) and deionized water (feed solution) are used, or tests in FO systems that reflect the membrane work conditions more, where dextran draw solution and NaCl feed solution are used ,16,17,18portance .4), ascorbic acid, hydroiodic acid, or hot strong alkaline solutions can be listed [Graphene oxide contains graphite structure sheets decorated with oxygen-containing groups with a thickness of one or a few layers of carbon atoms. GO may be reduced via thermal reduction, chemical reduction, or multi-step reduction with the use of more than one method. As effective chemical reducers hydrazine, metal hydrates . Unlike other concepts, naturally occurring sub-nanometric defects in graphene were the active filter paths of the membrane and the key to the solution. The novelty is the use of reduced graphene oxide which allowed for sealing larger defects resulting from graphene growth and transfer steps. The analysis of graphene after its growth stage, as well as during transfer and after transfer to the polymer substrates , was performed. Several reagents reducing graphene oxide were used and their influence on the morphology of the defect-sealing material was determined. Filtration tests were carried out in the FO system with the use of NaCl salt solution aiming to determine the dependence of semi-permeable properties on the graphene oxide reducing agent used.The aim of this work was to manufacture and investigate semi-permeable FO membranes based on HSMG®) according to the procedure described in detail in the patent  and the article [Monolayer polycrystalline graphene for composite membranes preparation was synthesized via the metallurgical method . It was used to prepare composite graphene membranes in each test. Membrane thickness equaled 110 µm and was declared by the manufacturer as having water permeability of ≥10 mL min−1 cm−2 bar−1 at a temperature of 25 °C. We transferred graphene on a polysulfone membrane side with minor porosity where pore diameter was from 0.1 to 1.0 μm. The density of the pores was 1.05 × 106 mm−2.Porous polysulfone membranes were used as graphene supporting substrates (MicroPES−3 (9.2 g of PMMA-100 mL of chlorobenzene), was used for covering graphene during the transfer procedure.Poly(methyl methacrylate) (PMMA) with a molecular weight of 996,000 g/mol of the Aldrich Chemistry Company, Burlington, MA, United States, dissolved in chlorobenzene , with a concentration of 0.10 mol dmThe solvent used to dissolve and remove the PMMA foil from graphene during the transfer procedure was 2-propanol with a technical grade of 70% .Graphene oxide with 0.4% dispersion in water (4 mg/mL) was purchased from the Advanced Graphene Products Company, Nowy Kisielin, Poland.4) A.C.S , L(+)-ascorbic acid (C6H8O6) A.C.S , and green tea leaves commercially available in the local market, were used.For the reduction of graphene oxide, diluted commercial 80% hydrazine hydrate , pure ethylenediamine A.C.S , 98.5 % sodium borohydride  pure p.a. from Chempur, Poland, was used. For membrane assembly in the grip of side-by-side diffusion cell Polydimethylsiloxane (PDMS), SYLGARD™ 184 Silicone Elastomer , was used.® graphene transfer process onto a polysulfone membrane was conducted using the electrochemical delamination method [2. This was followed by drop/blade coating graphene with PMMA in chlorobenzene as a temporary carrier layer. The polymer was dried at a temperature of c.a. 40 °C for 30 min. Delamination of the HSMG® graphene was carried out using a laboratory half-automatic station in 0.5 mol/L NaOH solution at a constant voltage of 4.5 V at a sample submersion angle of 35° and a submersion linear speed of 0.02 mm s−1. Then, graphene on PMMA foil was washed three times in deionized water. Graphene on polymer foil was placed on a wetted polysulfone membrane and roll pressed with a sponge roller and then annealed at 70 °C for 5 min. A gentle pressing was used to get rid of water and provide good attachment while avoiding damaging the graphene. Then it was placed in a chamber with boiling isopropanol to remove the PMMA-supporting layer. The graphene membrane was then washed twice in cold isopropanol to remove any polymer residues and air-dried.The HSMGn method . The proAfter transfer on the target, substrate graphene was subjected to SEM analysis (HITACHI S 3000 N). In this way, we established that no new cracks and tears are introduced to graphene at any stage of the transfer method.® graphene. It was prepared by the chemical reagent reduction of graphene oxide. rGO reduced with hydrazine without centrifugation of the reaction products was prepared via preparation of 1% solution of hydrazine in 50 mL of 0.4% GO in DI water suspension and left for 48 h to reduce at room temperature (RT).Reduced graphene oxide (rGO), listed in The reduction of GO via hydrazine and ethylenediamine was conducted via preparation of 1% solution of hydrazine and ethylenediamine in 50 mL of 0.4% GO in DI water suspension, respectively. The solution was kept for 48 h at RT. Next, the rGO was centrifuged . After being centrifuged, the washing procedure was applied. The reaction mixture was poured out and 50 mL of DI water was added. In the next step, rGO sediment was extensively vortexed and mixed using an ultrasonic cleaner for 15 min. The washing procedure was repeated six times .4 (0.4 g), as a reducing agent, was added to 50 mL of 0.4% GO in DI water suspension. To obtain rGO, the suspension-prepared mixture was kept with continuous stirring at room temperature for 12 h. Next, the suspension was washed according to the procedure described above [NaBHed above .In the next stage of the experiment process, the reduction was carried out using ascorbic acid (0.4 g) diluted in 50 mL of 0.4% GO deionised water suspension. The reaction mixture was kept for 48 h at RT with gentle stirring. After the reduction process, the rGO suspension was washed according to the procedure mentioned above .The last reducing agent used to reduce graphene oxide was green tea leaf extract. 15 g of dried tea leaves were boiled with 200 mL of DI water at 80 °C for 1h in a 250 mL flask to obtain the tea leaf extract. Next, the prepared solution was filtered. The 50 mL GO solution and 50 mL tea leaf extract were heated to 90 °C and then mixed in a ratio of 1:1 (vol. ratio). The reduction of GO was carried out with continuous stirring at 90 °C for 12 h. After this time, the above-mentioned washing procedure was applied .Raman spectroscopy measurements were performed using an inVia Renishaw Raman spectroscope equipped with a 532 nm laser. The laser power during the measurements was reduced to the value of 0.3 mW to avoid sample damage, while laser exposition time was 10 s. A 50× objective was used for all measurements.2 greater than 0.98.For the needs of spectral analysis, each peak was fitted to a single Lorentzian using the PeakFit software. The fits achieved an R−1 was measured by Fourier transform infrared spectroscopy . Spectra were recorded at a resolution of 2 cm−1 using a highly sensitive MCT-B detector (Telluride Mercury Cadmium Telluride). Measurements were made in the reflection mode with the use of the Sequelle DRIFT reflection adapter, for the incidence of the radiation beam equal to 20 degrees. Spectra were collected from 256 scans.The infrared absorption of GO and rGO samples in the spectral range from 4000 to 500 cmThe X-ray diffraction studies of graphene oxides were performed with the use of the PANALYTICAL Empyrean X-ray diffractometer . The diffraction patterns were collected using a tube with a Cr anode-emitting characteristic radiation with a wavelength of λ = 2.291 Å, operating at a voltage of 30 kV and current of 55 mA. Due to the high roughness of the graphene oxide samples deposited on nickel substrates, on the primary radiation beam, an X-ray lens with a cross collimator was used. On the reflected beam path, a 0.18 deg parallel beam collimator, 0.04 rad Soller slits, and a proportional detector were installed. The tests were carried out in the angular range from 2θ = 10–60°, with a 0.05° step, and time per step equal to 5 s.® in the amount of 30 µL per 1 cm2. After 5 min, the excess solution was washed off with a gentle stream of water. In the next step, another 10 µL/cm2 of rGO/water solution was applied on the graphene membrane and air-dried. Each time before use, the rGO solution was dispersed by means of ultrasound. Due to the hydrophobic nature of graphene, a water suspension of rGO tended to accumulate in graphene discontinuities (uncoated polysulfone area). In this way, graphene HSMG® defects were sealed. The preparation of each membrane was performed in the same way as presented in The as-prepared rGO suspensions and unreduced GO suspension were dispersed in distilled water at a concentration of 0.1%, respectively. Then the solution was applied onto a polysulfone membrane covered with graphene HSMG® graphene to the PS substrate and after sealing with reduced graphene oxide. The observation of the surface of the graphene membranes was performed using the HITACHI S 3000 N scanning electron microscope. The samples were placed in the chamber using a table pressed with a ring in such a way as to ensure good charge-discharge from the entire surface of the graphene composite area. The tests were performed at the intensity HV = 5 kV, in SE and AEE modes, which enabled the identification of defects and impurities in the structure. The contrast in AEE mode is the result of the differences in the electrical conductivity of the tested micro-areas.Once made, the graphene membranes were subjected to qualitative investigations. The tests were carried out after the transfer of HSMGIon separation effectiveness and water flow through membranes driven by osmotic pressure gradient were measured with a side-by-side diffusion cell with a 22 mm orifice. The volume of each chamber  was 64 mL .One of the cylinders was filled with 0.2 M NaCl as a draw solution and the second was filled with degassed, deionized, UV lamp-treated water as a feed solution.The membranes were sealed in a grip with a semi-liquid polydimethylsiloxane polymer which was then polymerized. This provided membrane stabilization and good sealing while causing no damage to the working part of a membrane.® graphene to the PS substrate and after sealing with reduced graphene oxide.After being made, the graphene membranes were subjected to qualitative investigations. The tests were carried out after the transfer of HSMGEach time after membrane assembly both cylinders with feed and draw solution were filled simultaneously to avoid membrane deflection. The tests were conducted at room temperature (20 °C) for 24 h. Each time the salt concentration was measured on each side of the membrane after the test. To evaluate water flux (J), the transport of water from the feed side to the draw side, driven by the osmotic gradient that resulted in a rise of water level in the draw side, was measured using a graduated glass tube during the test.Each experiment was repeated twice by replacing the solution in each cylinder.c is the molar concentration of the solute, R is the gas constant, and T is the temperature in Kelvin. The calculated pressure was 9.7 bar.The osmotic pressure was calculated based on the van’t Hoff equation (−2 h−1 bar−1) was calculated based on the equation V is the change of water volume in a container (mL), A is the membrane-active surface area (m2), t is time (h), and p is theoretical osmotic pressure owing to the concentration difference (bar). The ion’s flux (mol m−2 s−1) was calculated by dividing the change of salt concentration in the container with feed solution by the test time and the membrane surface. The degree of ion transport blocking efficiency was calculated relative to an uncoated polysulfone membrane (bare PSU), assuming 0% ion blocking efficiency is the same ion transport as bare PSU and 100% ion blocking is no ion transport.The water flux through the membrane (J)  may be considered as a function of the C/O ratio:In accordance with the work , differeinf-G app < 0; C/O < 10GO = D’ inf-G app < 25; 10 < C/O < 500rGO = 0 < D’ inf-G app > 25; C/O > 500Graphene = D’ app) is equal to −0.52, at the same time fulfilling the condition D’ inf-G app < 0, which is typical for GO.In view of the above, in the case of sample No. 1  the value of the difference .The difference in the D’ and Ginf-G app) amounting in both cases, ~13 . The value placed in this range is characteristic of the reduced graphene (rGO). The higher D’ and Gapp difference, the more reduced the GO. Therefore, based on the obtained results it can be stated that the most effective reduction has been achieved by the reaction of GO with hydrazine, which is also confirmed by the FTIR and XRD analysis.According to the Raman spectroscopy analysis, samples No. 2 and 3 (the hydrazine-reduced GO’s) show the highest value of  and 4 (GO reduced with L(+)-ascorbic acid). The difference between D’-Gapp) value was equal to 1.79 and 0.5, respectively, which means that both ethylenediamine and green tea turned out to be the least efficient reducing agents for graphene oxide in these experiments. However, in the case of the reactions with green tea the lowest level of the reduction of GO was obtained, which is also confirmed by the XRD and FTIR analysis.In Raman measurements, the least effective reduction of GO was obtained for samples No. 6 and 7, where  identified by the adsorption bands at 1240 cm−1 and 1075 cm−1 derived from the stretching vibrations of the C-O bonds. In addition, at 1627 cm−1, there is a typical maximum for stretching vibrations of C=C bonds taking place in the hexagonal ring of graphene oxide [−1, a wide band also appears, originating from both symmetric and asymmetric stretching vibrations of C-H bonds in aliphatic hydrocarbon chains attached to the GO ring structure [The spectrum of unmodified GO shown in ne oxide ,29,30. I−1  and at 1280 cm−1, which correspond to the stretching vibrations of C-N bonds, emerge [−1, corresponding to the stretching vibration of N-H bonds and characteristic for the NH2 group, appear. Additionally, in the spectrum of graphene reduced with non-centrifuged hydrazine, a maximum at 1530 cm−1, corresponding to the C-NH2 stretching vibrations, emerges along with a wide and distinct band in the range from 3500–3300 cm−1 related to the stretching vibrations of N-H bonds. This means that hydrazine centrifugation is necessary to clean the surface of the reduced GO to get rid of the toxic residues of the reducer used. Nitrogen-containing compounds allow not only for the reduction of GO but also the formation of bridges between carbon atoms in different rGO flakes [When it comes to GO reduction, hydrazine, sodium borohydride, and ascorbic acid turn out to be the best reducing agents and this can be observed in the IR absorption spectra. First of all, following reduction the band originating from the C=C vibrations shifts away from the position dedicated to GO. In hydrazine reduced material, the bands originating from hydroxyl and carboxyl groups disappear, while groups typical for C=N connections in the range of 1690–1640 cm, emerge ,31. In aO flakes ,22. On tO flakes .4. After reduction with this substance, no maxima assigned to -OH and -COOH groups are observed but, instead, an intense band at 1270 cm−1 originating from epoxy groups is present. In addition, a new peak emerges at 1592 cm−1, related to the presence of COO- anions, which is a consequence of the presence of the sodium cation in the reducer used and the formation of the carboxylic anion [Another effective reducing agent is NaBHic anion .2H8N2, the C=C peak is still at the constant 1627 cm−1 position. In the spectrum of GO reduced with green tea, apart from signals corresponding to carboxyl groups, epoxy, and other C-O connections characteristic for GO, absorption bands typical for this reducing agent, appear. Moreover, the presence of a maximum at 1655 cm−1 assigned to the stretching vibrations of the C=O bond in first-order amides, as well as that at 1327 cm−1, due to the stretching vibrations of aromatic amines of I and II order [−1 and 1056 cm−1 are concerned, they originate from stretching and deformation vibrations, respectively, of C-O bonds in the C-OH group of polysaccharides [2 amine groups are recorded in the spectral range from 3300–3150 cm−1 (stretching vibrations) and at 1580 cm−1 (deformation vibrations of N-H bonds in the -NH2 groups), and those originating from C-N bond stretching vibrations are observed at 1220 cm−1 [2- and -CH3 groups is also higher in ethylenediamine-reduced GO.Only in the cases of GO treated with GT and CII order ,31, is rcharides . FinallyThe reflection mode geometry X-ray diffraction pattern for a neat GO has a strong (001) diffraction peak indicating the preferred orientation of graphene oxide basal planes parallel to the sample plane. The two-theta position of the (001) GO diffraction peak can show a range from ~7–12 2theta (Cu Kα radiation) that corresponds to ~10–18 2theta for Cr Kα radiation, depending on the amount of residual water intercalated between basal planes in a GO film . InterplAn average number of layers per flake of GO and r-GO is calculated using the flake size and d-spacing parameters obtained from XRD analysis.n is the number of layers, D is the crystallite size, and d(001) is the interplanar distance.Here, The results of the explained estimations above for all samples are summarized in In sample No. 2 intense reduction of GO can be observed, but calculations of d, D, and n values also indicate a very intense conglomeration of remaining GO flakes and likely the exchange of pre-existing H-O bonds between flakes with reducing agent species. This effect is likely also related to the lack of centrifugation, the product of the hydrazine reduction reaction, and the formation of C-N, C=N bonds.In the case of sample No. 4, reducing agents caused the removal of H-O species from between GO flakes and the partial transformation into rGO, which is indicated by decreasing the d for GO and the appearance of the rGO peak.For sample No. 5, the reducing agent, however, caused a partial reduction of GO to rGO, but at the same time, the increment in d’s is observed and in crystallite dimensions.For sample No. 6, there is a shift towards lower 2Th values only. No rGO peak was observed which can indicate the applied reducing agent species added to existing H-O ones. In sample No. 7, the decrease of d interplanar spacing of GO is observed, however, no rGO peak appeared. The calculation of the “n” value suggests that the applied agent only caused the division of GO flakes without any reducing effect.In the examined group of samples, only sample No. 3 shows the complete reduction of GO without any additional effects.In all cases created, rGO is characterised by very close d, D, and n values.The membranes were manufactured and labeled as described in ® polycrystalline graphene at the stage of synthesis and/or transfer to a polysulfone substrate. On membrane 1, defects in the graphene layer were masked with graphene oxide. Large GO conglomerates covering the surface of HSMG® graphene are visible here. Membranes 2 and 3 were sealed with reduced graphene oxide as a result of the use of hydrazine. There is an even coverage of the rGO graphene surface, with no major conglomerates. As the AEE images show, there are no non-conductive sites, which proves a very good continuity of graphene layers supplemented with rGO. On membranes 4, 6, and 7 the coating is not as uniform as in the other cases (except membrane 1), some of the sealing material tended to accumulate in larger aggregates on the surface of the membrane, thereby forming large conglomerates GO/rGO. The surface of diaphragm No. 5 is also characterised by homogeneous coverage GO/rGO as for diaphragms 2 and 3. The wrinkles characteristic of graphene oxide/reduced graphene oxide can be seen here. The entire surface of HSMG® graphene is covered with such a wrinkled coating. Furthermore, all images of membranes with transferred graphene show reflections of the boundaries of copper grains from the growth substrate, however, this does not affect the continuity of graphene in these areas.In the presented results of osmotic tests for the as-prepared composite graphene membranes, the effectiveness of blocking the ion transport ranges from 30–95%. For the membrane with unsealed graphene (No. 8), no semi-permeable properties were noted, it was characterized by high ion transport and no water flux caused by osmotic pressure .−1 m−2 bar −1 and an ion blocking efficiency of approximately 60%.A reference to other options for the composite membrane preparation is also the membrane sealed with non-reduced graphene oxide. A water flux achieved for it is over 8 mL hThe reduction of GO with hydrazine (sample No. 2) and its use as a material for sealing defects in graphene increased the ion blocking efficiency for the membrane prepared in this way up to 87%, however, a water flow close to zero was noted.For membrane 3, in which a completely hydrazine-reduced graphene oxide was used as the sealing material, the same ion blocking efficiency as in membrane 2 was achieved, but with a significantly higher water flow. Here, in relation to membrane 1, ion blocking was higher at lower water flow rates. This phenomenon is associated with a reduced interplanar distance in the rGO flakes, a lower number of oxygen groups in reduced graphene oxide flakes, and, thus, the more accurate sealing of defects. In this case, the blocking of the ion flow and water molecules is also greatly influenced by the uniform coverage of the membrane surface by rGO and the low tendency to form conglomerates. On the other hand, the increase in water flow in membrane 3 with respect to membrane 2 with the same degree of ion blocking may be due to the greater presence of C=N and C-N bonds in membrane 3. The blocking of water flow through membrane 2 may also be influenced by non-centrifuged reduction reaction products.® also contributes to this high water flow. However, the resulting large rGO conglomerates, and the tendency to form clusters on the surface, do not sufficiently cover the defects in HSMG® graphene. Therefore, the migration of ions through this type of membrane is high and the repeatability of the results is worse.The most intense water flow was achieved for the membrane with vitamin C-reduced graphene oxide. In this case, the effective removal of OH and COOH groups, the reduction of the distance between the planes of non-reduced graphene oxide, and the small distances between the planes of reduced graphene oxide translated into such a sealing of large defects in graphene that the highest water transport was obtained under the influence of osmotic pressure. The ability to selectively coat the surface of graphene HSMG−1 m−2 bar−1 with an ion blocking efficiency of 70%. This is due to the very low degree of reduction of GO and the presence of nitrogen bonds, which further increased the interplanar distances, which was demonstrated in FTIR and XRD results. In this case also, conglomerate formation and GO aggregation on the HSMG® graphene surface did not sufficiently cover the defects, but selective coverage resulted in high water flow.Sealing graphene with ethylenediamine-reduced GO resulted in a water flow of 11.5 mL hGreen tea turned out to be an ineffective reagent, which not only had almost no effect on the reduction of graphene oxide but also the transport of water and ions was close to the one obtained for bare graphene. The low level of ion blocking, in this case, was also related to the formation of conglomerates and aggregation of GO on the surface of the graphene membrane. The low ability to cover defects in the graphene layer resulted in a very low water flow due to there being practically no osmotic pressure.All prepared membranes showed the stability of operation in more than one osmotic test, moreover, most often the second measurement resulted in a higher water flow and slightly higher ion transport than during the first measurement. It may be related to the intercalation of water molecules between the flakes of reduced graphene oxide and between graphene and the sealing rGO on the border of graphene defects.−2 h−1 . Only the solution based on green tea did not give positive results. Here, it is most likely that the low degree of sealing affected the generation of low osmotic pressure, which translates into low water flow. The optimal solution, from the point of view of the flow rate, and the degree of ion blocking, is the solution using GO reduced with ethylenediamine, with a water flow of 12 mL m−2 h−1 bar−1 and ion blocking at the level of 70%.The study showed that the graphene membranes created are semi-permeable to aqueous solutions. The effectiveness of blocking NaCl ions and the rate of water flow through the membrane are dependent on the degree of GO reduction used to cover HSMG