For cooled newborn infants, humidifier settings for normothermic condition provide excessive gas humidity because absolute humidity at saturation is temperature-dependent. To assess humidification of respiratory gases in patients who underwent moderate therapeutic hypothermia at a paediatric/adult intensive care unit, 6 patients were studied over 9 times. Three humidifier settings, 37-default , 33.5-theoretical , and 33.5-adjusted (optimised setting to achieve saturated vapour at 33.5°C using feedback from a thermohygrometer), were tested. Y-piece gas temperature/humidity and the incidence of high (>40.6 mg/L) and low (<32.9 mg/L) humidity relative to the target level (36.6 mg/L) were assessed. Y-piece gas humidity was 32.0 (26.8–37.3), 22.7 (16.9–28.6), and 36.9 (35.5–38.3) mg/L {mean } for 37-default setting, 33.5-theoretical setting, and 33.5-adjusted setting, respectively. High humidity was observed in 1 patient with 37-default setting, whereas low humidity was seen in 5 patients with 37-default setting and 8 patients with 33.5-theoretical setting. With 33.5-adjusted setting, inadequate Y-piece humidity was not observed. Potential risks of the default humidifier setting for insufficient respiratory gas humidification were highlighted in patients cooled at a paediatric/adult intensive care unit. Y-piece gas conditions can be controlled to the theoretically optimal level by adjusting the setting guided by Y-piece gas temperature/humidity. A number of clinical studies investigated the neuroprotective effect of therapeutic hypothermia to 32–34°C in a range of pathological conditions –5. HowevFor mechanically ventilated patients, respiratory gases are humidified close to saturated vapour at 37°C (43.9 mg/L), regardless of body temperature –10. IndeThe aim of this study was to examine humidification of respiratory gases at the Y-piece of the ventilator circuit in patients of paediatric and adult ICUs who are undergoing therapeutic hypothermia.This study was conducted under the approval of the Ethics Committee of Kurume University School of Medicine with informed consent from substitute decision-makers of the patients.Between July 2011 and November 2014, 3 children and 3 adults who underwent moderate hypothermia to 33-34°C at a tertiary emergency medical centre in Kurume, Fukuoka, Japan, were studied 9 times over different days .Three ventilators  were used according to the availability and the patient's condition. For these ventilators, oxygen and synthetic air are delivered from the central gas supply except for VELA, which compresses ambient air using its turbine. We used a pass-over humidifier  with ventilator-fixed circuits of either Dar  or Evaqua 2  .Data collection from the same patient was repeated up to twice in total with an interval of at least 24 h only after major changes in ventilator settings. Gases were assessed using a clinical, main-stream capacitive thermohygrometer  , 13 placValues are presented as mean  unless otherwise stated. Because of the lack of established thresholds for inappropriate Y-piece gas temperature and humidity during cooling, high and low temperature/humidity was defined based on clinical recommendations for normothermic patients that Y-piece temperature should be controlled to ±2°C from the target level, with its humidity >75% of saturated vapour at body temperature [Six patients of 28.0 (0.5 to 61.8) {median (range)} years old were studied nine times over different days. Three children used tracheal tubes of 4–5.5 mm in diameter, whereas three adults were intubated with tracheal tubes of 7–9 mm in diameter. Seven and two studies were performed in patients who were ventilated using patient-triggered ventilation and bilevel ventilation, respectively. A turbine air ventilator was used in an adult patient with the fraction of inspiratory oxygen of 0.21 when ambient temperature and humidity were 25.9°C and 36.6%, respectively (patient 6).A 5-month-old infant patient 1) developed pneumothorax and ventilator-associated pneumonia during cooling and required chest drainage and intravenous antibiotics (Tables  developeY-piece gas temperature and humidity were 39.1 (38.5–39.8)°C and 32.0 (26.8–37.3) mg/L, respectively. High temperature, high humidity, low humidity, and extremely low humidity were observed in 7, 1, 5, and 2 studies, respectively .Y-piece gas temperature and humidity were 36.4 (36.1–36.7)°C and 22.7 (16.9–28.6) mg/L, respectively. Low humidity and extremely low humidity were observed in 8 and 6 studies, respectively.Humidifier settings for the chamber outlet and the Y-piece temperature were 37.9 (36.6–39.2)°C and 37.5 (37.0–38.0)°C, respectively . Y-pieceUse of the default humidifier setting for normothermic conditions in patients cooled at paediatric and adult ICU resulted in higher temperature and lower humidity of Y-piece gases compared with the target levels for hypothermic conditions. This finding contrasted with our previous study in newborn infants, where both Y-piece temperature and humidity were higher than the target levels. Such a trend towards insufficient humidification in the current ICU cohort was exacerbated when the theoretically adjusted humidifier setting for body temperature was used and not observed when the humidifier setting was adjusted according to the Y-piece gas monitoring.For mechanically ventilated patients, respiratory gases are prepared till they become saturated vapour at 37°C 43.9 mg/L) or at least 75% of this level (32.9 mg/L)  mg/L or . Indeed,The exact mechanism of insufficient humidification in the current ICU cohort remains unknown. Current humidifying systems generally provide only modest humidity as opposed to the ideal level , 16. In Our previous and current study suggested that the Y-piece gas condition can be significantly altered by ventilator settings and patients' clinical conditions, suggesting the difficulty in predicting and preventing the incidence of inappropriate humidification of respiratory gases, especially in cooled patients. Nevertheless, when the humidifier setting was adjusted by obtaining feedback from Y-piece gas monitoring, high and low humidification was not observed. The humidifier used in the current study (MR 730) has been replaced by its successor model (MR 850), which provides fully automated adjustment of respiratory gases using feedback from energy consumption and gas flow, resulting in relatively more efficient humidification of gases , 18. TheThere currently is a lack of evidence to support the safety and benefit of a particular strategy in preparing respiratory gases during therapeutic hypothermia. Similarly, there is no established threshold to define inappropriate gas temperature and humidity for cooled patients. In our current study, thresholds for inappropriate Y-piece gas temperature and humidity were defined based on the recommendations released by the International Organization for Standardization for normothermic patients , which mHumidification of respiratory gases was different from the level, which are estimated from the humidifier setting in patients who were undergoing therapeutic hypothermia at paediatric and adult ICUs. With the default humidifier setting for normothermic patients, insufficient gas humidification was observed, the trend of which was exacerbated with the humidifier setting adjusted for the hypothermic body temperature. This is the first report to warn of the potential risk of inappropriate humidification in child and adult patients who are undergoing therapeutic hypothermia under mechanical ventilation. When the humidifier setting was adjusted with the feedback from the Y-piece gas temperature and humidity, respiratory gases were successfully humidified to the theoretical target level for hypothermic patients. Future studies are needed to confirm the incidence of inappropriate humidification during cooling in ICU patients and to test whether a new regimen with optimal gas preparation reduces ventilator-associated pneumonia and other serious adverse events encountered during therapeutic hypothermia.


Kip1 level. U0126, an ERK1/2 inhibitor, showed opposite effects. Leptomycin B (LMB), an inhibitor of chromosomal maintenance 1 (CRM1), attenuated nucleocytoplasmic p27Kip1 export and astroglial proliferation, although it up-regulated ERK1/2 phosphorylation and GFAP expression. Roscovitine ameliorated the reduced nuclear p27Kip1 level and astroglial proliferation without changing GFAP expression and ERK1/2 phosphorylation. U0126 aggravated SE-induced astroglial apoptosis in the molecular layer of the dentate gyrus that was unaffected by LMB and roscovitine. In addition, U0126 exacerbated SE-induced neuronal death, while LMB mitigated it. Roscovitine did not affect SE-induced neuronal death. The present data elucidate for the first time the roles of nucleocytoplasmic p27Kip1 transport in ERK1/2-mediated reactive astrogliosis independent of SE-induced neuronal death and astroglial apoptosis. Therefore, our findings suggest that nucleocytoplasmic p27Kip1 export may be required for ERK1/2-mediated astroglial proliferation during reactive astrogliosis, and that nuclear p27Kip1 entrapment may be a potential therapeutic strategy for anti-proliferation in reactive astrocytes.Reactive astrogliosis is a prominent and ubiquitous reaction of astrocytes to many types of brain injury. Up-regulation of glial fibrillary acidic protein (GFAP) expression and astroglial proliferation are hallmarks of reactive astrogliosis. However, the mechanisms that regulate reactive astrogliosis remain elusive. In the present study, status epilepticus  led to reactive astrogliosis showing the increases in GFAP expression and the number of proliferating astrocytes with prolonged extracellular signal receptor-activated kinases 1/2 (ERK1/2) activation and reduced nuclear p27 However, the mechanisms that regulate reactive astrogliosis are complex and remain elusive.Astrocytes are the most numerous non-neuronal cell types in the brain, which participate in the maintenance of extracellular glutamate level  are members of the mitogen activated protein (MAP) kinase family, which modulates the cell cycle re-entry and cell survival  is an anti-fungal agent and inhibits chromosomal maintenance 1 (CRM1)/exportin-dependent nuclear export. Furthermore, LMB has a potent anti-inflammatory  inhibitor, acts as a primary negative regulator of cell proliferation in a variety of cell types. In quiescent cells, p27Kip1 is localized in the nucleus and can be transported to cytoplasm via CRM1 in response to various stimuli. Furthermore, ERK1/2 signaling pathway down-regulates nuclear p27Kip1 level  astrocytes with prolonged ERK1/2 activation (phosphorylation) and reduced nuclear p27Adult male Sprague-Dawley (SD) rats  were used in the study. Animals were kept under controlled environmental conditions  with free access to water and standard laboratory food. All animal experiments were approved by the Institutional Animal Care and Use Committee of the Hallym University . All reagents were obtained from Sigma-Aldrich , unless otherwise noted.SE was induced by a single dose (380 mg/kg) of pilocarpine in rats, as previously described . Thereafter, an infusion kit was connected to an osmotic pump  containing: (1) vehicle, (2) U0126  into the right lateral ventricle  under Isoflurane anesthesia , according to the manufacturer’s instructions. The protein concentration in the supernatant was determined using a Micro BCA Protein Assay Kit .Three and 7 days after SE, animals were deeply anesthetized with urethane anesthesia  and perfused with phosphate-buffered saline  followed by 4% paraformaldehyde in 0.1 M phosphate buffer . The brains were removed, and cryoprotected by infiltration with 30% sucrose overnight. Thereafter, the tissues were sectioned with a cryostat at 30 μm and consecutive sections were collected in six-well plates containing PBS. For western blot study, the hippocampus was rapidly removed and homogenized in lysis buffer. To analyze nuclear p27® Fluorescein In Situ Apoptosis Detection Kit  according to the manufacturer’s protocolFluoro-Jade B (FJB) staining was performed as previously described /mouse anti-GFAP  antisera in PBS containing 0.3% Triton X-100 overnight at room temperature. After washing three times for 10 min with PBS, the sections were also incubated in a mixture of FITC- and Cy3-conjugated secondary antisera  for 2 h at room temperature. The sections were washed and mounted on gelatin-coated slides. All images were captured using an Axio Imager M2 microscope and AxioVision Rel. 4.8 software . For quantitative analysis, images of the CA1 region and DG were captured , and areas of interest (1 × 105 μm2) were selected. Thereafter, two different investigators performed FJB or TUNEL- or Ki-67 positive cell counts and measured p27Kip1 fluorescent intensity using AxioVision Rel. 4.8 software.Free-floating sections were first incubated with 10% normal goat serum , and then reacted with mouse anti-GFAP antibody  in PBS containing 0.3% Triton X-100 and 2% normal goat serum overnight at room temperature. After washing, sections were incubated sequentially, in horse anti-mouse IgG  and ABC complex . Between the incubations, the tissues were washed with PBS three times. The sections were visualized with 3,3′-diaminobenzidine (DAB) in 0.1 M Tris buffer and mounted on the gelatin-coated slides. Some sections were incubated in a mixture of rabbit anti-GFAP /mouse anti-Ki-67  or rabbit anti-p27Kip1  antibody. Immunoreactive bands were detected and quantified on ImageQuant LAS4000 system . The rabbit anti-β-actin  or rabbit anti-poly(ADP-ribose) polymerase-1  primary antibody was used as internal reference.Western blotting was performed according to standard procedures. Briefly, Tissue lysate proteins were blotted onto nitrocellulose transfer membranes , then incubated with mouse anti-GFAP , rabbit anti-ERK1/2 , rabbit anti-pERK1/2  or rabbit anti-p27post hoc test for multiple comparison. Values are presented as mean ± SEM. Differences were considered as significant for p < 0.05.All data obtained from the quantitative measurements were tested for the normality and equality of variance. Thereafter, data were analyzed by one-way analysis of variance (ANOVA) coupled with Bonferroni’s First, we investigated the effects of U0126 and LMB on GFAP expression and ERK1/2 phosphorylation in the hippocampus 7 days after SE. Consistent with our previous studies  inhibitor, is a poor ERK1/2 inhibitor with IC50 values of 34 μM and 14 μM for ERK1 and ERK2, respectively  showed the reduction in nuclear p27Kip1 level in astrocytes (Figures p < 0.05 vs. control animals; Figures p < 0.05 vs. vehicle; Figures p < 0.05 vs. control animals; Figures p < 0.05 vs. vehicle; Figures Kip1 export may not be sufficient to induce astroglial proliferation during the process of reactive astrogliosis.Since U0126, LMB and roscovitine ameliorated the reduced nuclear p27 Figures , 4, we ep < 0.05 vs. control animals; Figures p < 0.05 vs. vehicle; Figures We have reported that SE results in the massive astroglial apoptosis in the molecular layer of the dentate gyrus and programmed CA1 neuronal necrosis (Kang et al., p < 0.05 vs. control animals; Figures p < 0.05 vs. vehicle; Figures p < 0.05 vs. vehicle; Figures p < 0.05 vs. vehicle; Figures SE also resulted in massive neuronal death in CA1 neurons, but not DGC (Kip1 entrapment may be required for ERK1/2-mediated astroglial proliferation during reactive astrogliosis, although ERK1/2 activation may play an important role in up-regulation of GFAP expression in reactive astrocytes.The major findings in the present study are that the release of nuclear p27Reactive astrogliosis is a prominent and ubiquitous reaction of astrocytes to many types of brain injury, which is relevant to the poor regenerative capacity of the adult brain (Mandell et al., Kip1 is one of the primary negative regulators of cell proliferation in a variety of cell types. p27Kip1 level is decreased in response to mitogenic stimulations. Furthermore, up-regulated p27Kip1 protein level causes cells to arrest in the G1 phase of the cell cycle (Connor et al., Kip1 (Meloche and Pouysségur, Kip1 entrapment in astrocytes accompanied by the reduced ERK1/2 phosphorylation following SE. However, LMB decreased SE-induced nucleocytoplasmic p27Kip1 transport in astrocytes, in spite of ERK1/2 hyperactivation. This finding is consistent with a previous study reporting that CRM1 inhibition mediates persistent ERK1/2 hyperactivation and leads to G1 cell cycle arrest (Pathria et al., Kip1, would also inhibit reactive astrogliosis. Further studies are needed to elucidate the regulatory mechanisms of ERK1/2 activity by LMB. In the present study, roscovitine also preserved nuclear p27Kip1 level without altered ERK1/2 phosphorylation. Furthermore, these nuclear p27Kip1 entrapments by three different compounds were concomitant with the reduced number of Ki-67 positive proliferative astrocytes. Therefore, our findings suggest that nucleocytoplamic p27Kip1 export may be required for ERK1/2-mediated astroglial proliferation during reactive astrogliosis.p27Since astroglial viability in response to oxidative stress is improved by U0126 (Regan et al., Kip1 entrapment against SE insults. Otherwise, it is likely that the efficacy of LMB on p27Kip entrapment and the efficiency of nucleocytoplasmic p27Kip export in post-mitotic neurons may be distinct from those in proliferative astrocytes following SE. Regardless of the results concerning neuronal death and astroglial apoptosis, our findings indicate that the inhibitory effects of U0126, LMB and roscovitine on astroglial proliferation may be independent of neuronal death and astroglial apoptosis.On the other hand, we have recently reported that LMB attenuated SE-induced programmed CA1 neuronal necrosis via ERK1/2 activation (Min et al., Kip1 transport may differently contribute to the proliferation and vulnerability of A1/A2 astrocytes in response to brain injury. Further studies are needed to elucidate the regulatory mechanisms of ERK1/2, CDK5 and p27Kip1 in the acquisition of alternative phenotypes of A1/A2 astrocytes.Recently, it has been reported that neuroinflammation and ischemia induce two different types of astroglial reactivity termed “A1” and “A2”, respectively (Zamanian et al., Kip1 transport during reactive astrogliosis. Therefore, our findings suggest that nuclear p27Kip1 entrapment may be a potential therapeutic strategy for anti-proliferation in reactive astrocytes rather than ERK1/2 inhibition.To the best of our knowledge, the present data validate for the first time the roles of ERK1/2 and CRM1 in astroglial proliferation via nucleocytoplasmic p27T-CK designed and supervised the project. J-EK and T-CK performed the experiments described in the manuscript, analyzed the data and wrote the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The long-term test illustrated the degradation in ECSA exhibited the order of Pt/C (33%) > Pt/cG (7%). The values of the utilization efficiency were calculated to be 64% for Pt/cG and 32% for Pt/C.Due to its special electronic and ballistic transport properties, graphene has attracted much interest from researchers. In this study, platinum (Pt) nanoparticles were deposited on oxidized graphene sheets (cG). The graphene sheets were applied to overcome the corrosion problems of carbon black at operating conditions of proton exchange membrane fuel cells. To enhance the interfacial interactions between the graphene sheets and the Pt nanoparticles, the oxygen-containing functional groups were introduced onto the surface of graphene sheets. The results showed the Pt nanoparticles were uniformly dispersed on the surface of graphene sheets with a mean Pt particle size of 2.08 nm. The Pt nanoparticles deposited on graphene sheets exhibited better crystallinity and higher oxygen resistance. The metal Pt was the predominant Pt chemical state on Pt/cG (60.4%). The results from the cyclic voltammetry analysis showed the value of the electrochemical surface area (ECSA) was 88 m Carbon materials are widely used as the supports for deposition of precious metal nanoparticles in heterogeneous and electrochemical catalysis ,2. The p2/g) [Herein, graphene, a monolayer of carbon atoms in a crystal lattices and the basal plane of graphite composed of a honeycomb arrangement of carbon atoms, receives special interest as a catalyst support in PEMFCs due to its distinct electronic, mechanical and structural properties, such as high electrical and heat conductivity, high chemical stability and large surface-to-volume ratio  ,4. Howevet al. [2/g, higher than that of commercial Pt/C (30.1 m2/g). Kou et al. [2/g, 1.7 times that of Pt-Ru/Vulcan) and methanol oxidation activity  [et al. [2/g, higher than that of Pt/graphene (42.0 m2/g). In addition, some studies also investigated the effects of the spacers between metal nanoparticles and the graphene sheets, such as carbon nanotubes [Li et al.  preparedu et al.  studied /Vulcan) . Seo et anotubes , carbon anotubes , or indianotubes .It was observed that very small and highly dispersed PtRu nanoparticles decorated on a graphene support using simple surfactant-free synthesis processes possessed excellent activity and stability compared with conventional Pt/C (E-TEK) for the electrooxidation of biomass-derived glycerol . The sulIn this study, Pt nanoparticles were deposited on citric acid-treated graphene sheets (denoted as cG) using a reverse micelle method. Pt nanoparticles supported on carbon black (Pt/C) is currently considered the most promising electrocatalyst on PEMFCs. However, the corrosion of carbon black under operating conditions restricted the applications. Therefore, the graphene was applied to overcome this problem. To enhance the interfacial interactions between the graphene sheets and the Pt nanoparticles, the surface oxides were introduced onto the surface of graphene sheets. The products were characterized by high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The cyclic voltammetry (CV) technique was used to measure the ECSA, stability and utilization efficiency of the catalysts. One commercial Pt/C (Johnson Matthey) was used for comparison.6H8O7), as follows: 200 mg of graphene sheets were added to the citric acid aqueous solution (1.6 mM) and subjected to 15 min ultrasonic treatment, followed by vigorous stirring for 1 h using a magnetic stirrer. The ultrasonic treatment was conducted using an ultrasonic cleaner  at a frequency of 46 kHz and a power of 150 W. The solvent was removed by filtering and the samples were heat-treated in a muffle furnace at 300 °C for 30 min. This product was denoted as cG.The commercial graphene sheets (denoted as GS) used in this study were provided by Legend Star International Co. . The oxygen-containing functional groups were introduced onto the surface of the graphene sheets by treating them with citric acid  . Hexachloroplatinic acid (H2PtCl6·6H2O) solution (3 mL of 0.086 M in deionized water)  was mixed with tetraoctylammonium bromide 4Br)  solution (4 mL of 0.18 M in toluene) and vigorously stirred for about 30 min at room temperature. During this process, PtCl62− ions are transferred from the aqueous solution to the organic layer (toluene), using ToAB as the phase-transfer catalyst. The orange-colored organic layer was extracted and 450 mg of DDT (capping agent) was added and stirred for 30 min. 200 mg cG was then added with constant stirring for 1 h. 10 mL of 0.25 M sodium formate (HCOONa) aqueous solution was added drop-wise at 60 °C, to reduce the Pt ion. The solid product was filtered and rinsed with ethanol to remove excess DDT and copious amount of warm deionized water was used to remove the remaining sodium formate. The resulted Pt/cG products were dried at 100 °C for 3 h and further heat-treated at 800 °C for 2 h in a tubular furnace in an argon atmosphere. The deposition of Pt particles on the oxidized graphene sheets was performed using the colloidal method , involvi3/min) with a heating rate of 10 °C/min, using a thermogravimetric analyzer (Dynamic TGA Q500 in TA Instrument 5100)  to measure any changes in the weight of the sample as a function of temperature (TGA plot) and the rate of weight loss versus temperature . The residual mass was used to estimate the Pt content deposited on the surface of the graphene sheets. The XRD patterns were taken with an X-ray powder diffractometer  to give detailed information about the crystallographic structure of the materials. The radiation used was Cu Kα with a wavelength of 0.15418 nm, a voltage of 30 kV and a current of 20 mA. The value of 2-theta (2θ) ranges from 10° to 90°, where θ is the diffraction angle, with a scanning speed of 4°/min. XPS was used to determine the number and type of functional groups present on the surface of the samples, using a spectrophotometer . A twin anode Mg X-ray source (hν = 1253.6 eV) was used, at a voltage of 15 kV and a power of 400 W. For calibration purposes, the C1s electron binding energy that corresponds to graphitic carbon was set at 284.6 eV. A nonlinear least squares curve-fitting program  was used for deconvolution of the XPS spectra. The FT-IR spectra were recorded using a Fourier transform infrared spectroscope  with KBr pellets in the 4000–400 cm−1 region to characterize the functional groups on the samples.HRTEM images were obtained using a transmission electron microscope  , to determine the interior microstructure of the graphene sheets and the morphology and size distribution of the Pt particles deposited on the graphene sheets. The oxidation resistance of the samples was determined in flowing air , and isopropanol, where the Nafion® content in the thin-film electrocatalyst layer was 25 wt %. A Pt wire and a saturated calomel electrode (SCE) were used as the counter and reference electrodes, respectively. The measurements of CV were conducted at room temperature using 0.5 M H2SO4 as the electrolyte solution at a scan rate of 20 mV/s from −0.2 to 1.0 V vs. SCE.A CHI 613C electrochemical workstation  was employed for the electrochemical study of carbon-supported Pt samples. A three-electrode electrochemical cell was constructed for CV measurements, through which the ECSA of the Pt nanoparticles was determined. The working electrode was a thin layer of Nafionet al. [The morphology of the prepared catalyst was observed using HRTEM. et al.  and sligThe TGA and DTG profiles measured in flowing air for all samples are shown in XPS analysis was used to elucidate the surface compositions and the oxidation states of the materials. The XPS survey scan spectra of the samples revealed the compositions of the most external surface. Data from the XPS survey spectra of the GS and cG a indicat3)) obviously increased once the citric acid oxidation was applied. Moreover, the content of the –COOH groups was also significantly enhanced and the surface became much more active due to the decrease in the π-π* transitions in aromatic rings.The high-resolution XPS spectra of the C1s region for GS and cG were illustrated in et al. [−1 were attributed to deformation of the –OH bond and CO–H groups. The stretching vibrations of the carbonyl or carboxyl groups and the C–O bond were observed at ~1670 and 1100 cm−1, respectively.To gain a better understanding of the results noted above, high-resolution O1s spectra of GS and cG were illustrated in et al. ,17. The et al. ,19. The The major peaks observed in the survey scan spectra of Pt/cG and Pt/C (JM) were due to the C1s, O1s, and Pt4f photoelectrons. 2 [The deconvolution of the XPS spectra over the Pt4f region, shown in 2 , and thevs. SCE. Compared to that of the Pt/C, the Pt nanoparticles deposited on the graphene sheets possessed a larger loop, especially a wide double layer region, indicating the system’s greater ability to store electric charges. The ECSA is a very significant parameter indicating the intrinsic electrocatalytic activity of a Pt catalyst. The values of the ECSA for Pt/cG and Pt/C were calculated to be 88 and 46 m2/g Pt, respectively, based on a monolayer hydrogen adsorption charge of 0.21 mC/cm2 on polycrystalline Pt. A higher ECSA of the Pt/cG could be attributed to the small Pt nanoparticles and the efficient formation of zero-valence metallic Pt such that the fuel gases could attach to the redox sites on Pt nanoparticles. Note that the Pt/cG required much more activation time to develop its electrochemical activity.The cyclic voltammogram for the Pt/cG was displayed in vs. SCE) and the values of ECSA were evaluated. The dependence of the values in ECSA on the number of cycles  and d is mean diameter of Pt nanoparticles (nm). The values of the η were calculated to be 64% for Pt/cG and 32% for Pt/C. The results implied oxidized graphene sheets were an effective support for Pt depositions.In addition, the Pt utilization efficiency (η) is also the essential parameter to describe the catalyst performance, which was calculated by dividing ECSA by the chemical surface area (CSA) . The CSA2/g (Pt/cG) and 46 m2/g (Pt/C), respectively. The long-term test illustrated the degradation in ECSA exhibited the order of Pt/C (33%) > Pt/cG (7%). The values of the η were calculated to be 64% for Pt/cG and 32% for Pt/C. Therefore, Pt nanoparticles deposited on functionalized graphene sheets should produce a promising electrocatalyst.The results showed the Pt nanoparticles on Pt/cG were uniformly dispersed on the surface of graphene sheets by the reverse micelle method, where the mean size of the Pt particles was 2.08 ± 0.52 nm, and the average size of the Pt particles on Pt/C (JM) was 1.96 ± 0.50 nm. The Pt nanoparticles deposited on graphene sheets exhibited better crystallinity and the sample had a higher oxygen resistance. The metal Pt was the predominant Pt chemical state on Pt/cG (60.4%) and Pt/C (53.2%). The results from CV analysis showed the values of ECSA were 88 m


A full-cell incorporating graphene balls increases the volumetric energy density by 27.6% compared to a control cell without graphene balls, showing the possibility of achieving 800 Wh L−1 in a commercial cell setting, along with a high cyclability of 78.6% capacity retention after 500 cycles at 5C and 60 °C.Improving one property without sacrificing others is challenging for lithium-ion batteries due to the trade-off nature among key parameters. Here we report a chemical vapor deposition process to grow a graphene–silica assembly, called a graphene ball. Its hierarchical three-dimensional structure with the silicon oxide nanoparticle center allows even 1 wt% graphene ball to be uniformly coated onto a nickel-rich layered cathode via scalable Nobilta milling. The graphene-ball coating improves cycle life and fast charging capability by suppressing detrimental side reactions and providing efficient conductive pathways. The graphene ball itself also serves as an anode material with a high specific capacity of 716.2 mAh g Here, the authors report a graphene-silica assembly which could be coated onto a nickel-rich cathode via a scalable process for considerably improved electrochemical performance. In the presence of such graphene balls, a full cell benefits from an increased volumetric energy density by 27.6%. However, as electric vehicles (EVs) have penetrated LIB markets, key electrochemical properties have imposed more challenging standards; while higher energy densities are desired for increased driving mileage, enhanced reaction kinetics are demanded for fast charging and high rate operations. Safety is also definitely a critical factor for EV applications. A formidable challenge lies in overcoming the trade-off relation among these key properties; it is usually nontrivial to improve one property without sacrificing others.The ongoing development of lithium-ion batteries (LIBs) has resulted in remarkable improvements in various aspects of their operation, including energy density, power density, cycle life, and safety. At present, mobile IT devices account for a significant portion of LIB applications, where the operating specifications of current state-of-the-art LIBs are mostly satisfactory5 and incorporation of carbon nanomaterials8 as conductive agents have demonstrated improved charging rates by reducing ion diffusion distance and internal resistance, most of those approaches still require further improvement before they can be implemented in current LIB technology. The tap-densities of nanomaterials are far lower than those of conventional micro-particles, which is detrimental to volumetric energy density, a crucial factor for many LIB applications than the gravimetric counterpart. In a similar context toward reduction in internal resistance, the integration of carbon nanomaterials such as graphene has proven effective in increasing the electric conductivity of lab-scale electrodes. However, achieving a uniform distribution of a small weight content  of carbon nanomaterials in a large-scale slurry process has yet to be demonstrated. The modification of existing active materials by doping with foreign elements10 or stoichiometric control13 can also increase the diffusivity of Li ions and thus the charging rate of conventional active materials with micrometer dimensions. Most of those approaches are, however, effective at the expense of specific capacity.Such a trade-off relation is particularly obvious between energy density and fast charging (or power capability). While the use of nanomaterials as active components2 counterparts, it is well known that the inevitable cation-mixing during charging degrades the layered framework to spinel or rock-salt structures, along with unwanted side reactions at the electrode surface.Furthermore, beside energy density and fast charging, achieving long cycle life, especially at high temperatures , still remains a challenge for advanced LIBs that incorporate high-capacity electrode materials. While nickel (Ni)-rich and Li-rich layered oxide materials are considered as upcoming cathode materials due to their superior specific capacities compared to those of classical LiCoOConsidering the efforts undertaken so far, one of the most realistic solutions for immediately achieving fast charging of cathode materials with a negligible loss in energy density and cycle life involves finding conductive protective materials that can be coated uniformly on the active materials with a minimal content. Finding advanced anode materials is also essential because current graphite anodes suffer from Li metal deposition upon high rate charging.x) assembly, called a graphene ball (GB), as a coating material for high-capacity Ni-rich layered cathode materials as well as an LIB anode material. Each GB is composed of a SiOx nanoparticle center and surrounding graphene layers, constituting a three-dimensional (3D) popcorn-like structure. The SiOx nanoparticles play a crucial role in multiple aspects, such as avoiding the formation of a silicon carbide (SiC) layer at the SiOx–graphene interface during graphene growth, ensuring uniform coating of GB onto the cathode material, and providing a high specific capacity when GB is used as an anode material. The uniform coating of GB on the Ni-rich layered cathode enhances the interfacial stability with the electrolyte and the electronic conductivity over the electrode, improving the cyclability and fast charging capability of the cathode substantially. Taking the unique advantages of GB, the full-cell consisting of the GB-coated cathode and GB anode demonstrates the possibility of high volumetric energy density near 800 Wh L−1 in a commercial cell condition, together with 78.6% capacity retention after 500 cycles at 5C and 60 °C.Here we report a graphene–silica . OH− is also simultaneously produced via the following reaction:x provides catalytic sites for graphene growth, and OH− serves as a mild oxidant to facilitate the graphitic carbon formation toward graphene15. The role of mild oxidants on graphitic carbon formation was recently rationalized16 in a way that, without a mild oxidant, the formation of amorphous carbon is more dominant. However, in the presence of a mild oxidant, it was discovered that the reaction toward CO or CO2 formation is preferred for carbon atoms that would otherwise have evolved into amorphous carbon. In fact, the facile growth of graphene using metal catalysts is known to occur in a similar manner19, where the oxygen remaining on the metal surface leads to the preferential reaction toward graphitic carbon formation. The presence of a mild oxidant prevents the formation of silicon carbide (SiC) layer at the surface of SiOx because the oxidant prevents the reduction of Si toward SiC formation19.In order to synthesize the popcorn-like GB, we developed a chemical vapor deposition (CVD) process for graphene growth. CH4, at temperatures below 900 °C, graphene barely grew. In contrast, at 1050 °C and above, graphene growth became too aggressive toward graphite formation   and (101) planes of graphite, grew continuously  analysis  mapping  spectra obtained during the growth indicate that as the CVD process progresses, the peaks at 2sly Fig. , supportsis Fig. 22,23. Thsis Fig.  reconfiring Fig. , it was 002) and 01 planes29 based on Hummer’s method, achieving a uniform coating with a limited content of graphene is nontrivial due to agglomeration, which arises from the strong electrostatic interaction between graphene sheets. In an effort to overcome the agglomeration issue, a different approach, such as the crushing of graphite employing a ball-milling process, has been introduced30. However, this process is usually slow (>6 h) and, more critically, can harm the crystallinity of the host material. It should also be noted that amorphous carbon coating by CVD processes is not applicable to Ni-rich oxide materials32 because the CVD processes extract transition metals (TMs), perturbing the original crystal structure of the host material.Because of its atom-thick-layered morphology, graphene has been considered to be one of the most ideal materials for surface protective coating of high capacity layered cathode materials. However, in the case of well-known solution processes0.6Co0.1Mn0.3O2 powder (size = ~10 µm) at a minimal content of 1 wt% via a mild Nobilta milling process. The coating process is also quite fast (~10 min at 3000 rpm). The SiOx seeds play a critical role in enabling this uniform coating at low weight contents. The SiOx seeds account for 57.5 wt% of the GB , the active material occupies 96–97 wt% of the electrode to maximize the volumetric energy density3. In the case of Ni-rich active materials, because of their lower electronic conductivity, a content of ~92 wt% is presently accepted as an optimal value, with a conductive agent and binder each accounting for ~4 wt%.To test the effect of the GB coating on battery performance, both pristine NCM and GB-NCM were first examined in a half-cell configuration, using a Li metal disk as a counter and reference electrode. We first discuss the electrode conditions that we employed, to emphasize the commercial viability of the GB-based approach. In current commercial LIB cathodes based on LiCoO2-based electrodes, an electrode consisting of 97 wt% NCM active material, 0.5 wt% super P, 1.0 wt% GB, and 1.5 wt% polymeric binder  was prepared  and pristine NCM  electrodes delivered 760 and 570 mAh cc−1, respectively  enabled by the enhanced conductivity due to the integrated GB increased the volumetric capacity of the electrode by ~33.3%; at the given gravimetric capacity of 190 mAh g−1), they exhibited quite similar charging and discharging capacities (195.18 and 188.50 mAh g−1 for pristine NCM vs. 198.24 and 191.7 mAh g−1 for GB-NCM) as well as consistent profiles, implying that the implementation of GB did not perturb the original electrochemical properties of the NCM active phase.As displayed in Supplementary Fig. −1 to 188.4, 183.5, 175.3, 161.6, 131.2, and 86.1 mAh g−1, respectively  and 126.7% (134.9 vs. 59.5 mAh g−1) higher capacities at 2 and 10C, respectively.However, fast charging capability was clearly different for both electrodes Fig. . For thiely Fig. . In cont °C Fig. , the gap33. This cation mixing accelerates the extraction of TM ions to the electrolyte, boosting side reactions at the electrode-electrolyte interface. This unstable interface is indeed fatal to the cycle life of NCM and is amplified during over-charging and at high temperature.The integration of GB also had a remarkable effect on the cyclability of NCM. It is well known that the charging process degrades the cyclability of Ni-rich layered materials; during charge, TM cations tend to migrate to the neighboring Li-slabs, leading to the so-called Li-TM mixing and consequently phase transition from the layered to a spinel even to a rock-salt phasex nanoparticles, which scavenge fatal HF34, in addition to the surface protection of GB against side reactions involving the electrolyte. The protective role of GB was reflected in the electrochemical impedance spectroscopy (EIS) analysis  process. The GB electrode upon the CIP process delivered a reversible capacity of 716.2 mAh g−1 or 787.8 mAh cm−3 at an areal capacity of 2.7 mAh cm−2  due to the deposition of Li metal on the electrode surface. In an attempt to overcome this limitation of graphite, the GB grown for 30 min was evaluated as an anode material under the half-cell configuration. To this end, the GB anode was pressed to increase its tap density to 1.1 g cm.1C Fig. . The rat−1), starting from 382.6 mAh g−1, the specific capacity ended at 336.7 mAh g−1 after 500 cycles, corresponding to 88.0% retention. At 60 °C and 5 C, the specific capacity started at a higher value of 524.1 mAh g−1 owing to the aforementioned enhanced kinetics and preserved 451.2 mAh g−1 for 500 cycles, leading to 86.1% retention. The relative worse capacity retention at 60 °C is ascribed to less stable SEI formation around the GB, although further investigation is required to clarify. During the given 500 cycles, the electrode thickness increased only 18% from 30.5 to 36.0 μm , the given capacity increase predicts that the volumetric energy density of the GB-NCM//GB cell could approach 800 Wh L−1 in a commercial cell setting, a remarkable milestone in the development of LIBs for next-generation EVs. Graphene flakes produced by the solution-based exfoliation of graphite was previously integrated with LiFePO4 cathode to build a full-cell38. Despite the decent cyclability, the graphene nanoflake anode is expected to offer a smaller volumetric capacity than that of the GB containing high capacity SiOx, leading to an inferior volumetric energy density of the corresponding full-cell.The stable cycling of the GB half-cell prompted us to examine a full-cell in pairing with GB-NCM  images Fig.  show theFast charging capability is considered critical to the successful adoption of all-electric vehicles by the public; however, sacrificing energy density to achieve an enhanced charging rate is not desirable. To resolve this dilemma, one feasible approach for high capacity metal oxide cathodes would be to develop a uniform coating that utilizes a minimal content of a conductive carbon component to enhance electric conductivity, which could be adopted immediately with minimal commercial interruption. At the same time, advanced anode materials that can withstand high rate charging without Li metal deposition are another “must-item” to incorporate.In this respect, the proposed addition of a limited amount of GB to NCM cathodes would not require a substantial change in the mixing conditions of slurry preparation, which is presently a major obstacle to the implementation of a new material in LIB manufacturing. Unlike many other LIB electrodes, which can be carbon-coated via an established CVD process, Ni-rich layered cathode materials are not compatible with high-temperature carbonization processes because of undesired Ni extraction, thus limiting viable options to the physical mixing of carbon nanomaterials. At the same time, using physical mixing processes to produce a homogeneous electrode coating with a minimal content of carbon conductive materials is also problematic, because spontaneous agglomeration preferentially occurs, reducing interactions with the active particles.x centers of the GB. The GB can also serve as a high-capacity anode with robust structural stability for prolonged cycles. The formation of GB is accomplished in our CVD process under exclusive CH4 flow, which allows 3D graphene growth from the catalytically active sites of SiOx nanoparticles. This process serves as the basis for the enhanced charging capability and cyclability observed in this study. The current GB coating can also be applied to a range of battery electrodes that suffer from unstable interfacial properties and poor electronic conductivity.We resolved this challenge by employing a scalable Nobilta milling process that allows GB to be homogeneously integrated with the active powder by utilizing the shear force that originates with the SiOIn a broader perspective, the present mixing approach can be more generally expanded to a variety of graphene-based composites whenever it is desirable to homogeneously integrate graphene with ceramic materials. Other high-strength and heat-radiation applications could immediately benefit from the given approach.2, fumed SiO2 nanoparticles  were introduced into a fixed-bed vertical tube reactor made of quartz40 . The feed gas was fed through the reactor-containing bed from the top at atmospheric pressure. The loading of SiO2 in each batch was 0.3 g. Initially, the system was heated to a target temperature  at a ramping rate of 23 °C min−1 while 50 sccm CH4 was flowed. The temperature was maintained for 5, 30, 60, and 240 min, and the system was then cooled down to room temperature (25 °C) while pure N2 gas was flowed. For the samples treated in H2 atmosphere, a mixture of H2 (70%) and CH4 (30%) was flowed at 1000 °C for 10 min.For the direct growth of graphene over the surface of SiO0.6Co0.1Mn0.3O2  was first mixed with 30 min grown GB using a pestle and mortar. The GB content was 1 wt% of the entire mixture. The coating of GB was achieved at ambient temperature using a Nobilta mini bowl , in which a rotating four-way blade is placed with the rotation axis oriented along the reactor tube, and the gap between the blade and reactor wall is 5 mm. During the milling process, the blade was rotated at 3000 rpm for 10 min, and as a result, a controlled shear stress was continuously applied to the GB and NCM mixture.LiNiλ = 1.54Å). The scan rate and interval were 4º min−1 and 0.02º, respectively. XPS measurements were performed using a Physical Electronics spectrometer  with an Al Kα source (1486.7 eV). The carbon content of GB was quantitatively analyzed using a thermogravimetry analyzer (METTLER TOLEDO TGA/DSC1). High-resolution transmission electron microscopy (HRTEM) imaging and diffraction pattern (DP) analysis were carried out using an FEI Titan Cubed 60–300 equipped with double Cs correctors and Gatan Quantum 965. The samples were also visualized using field emission scanning electron microscopy  to monitor the changes in morphology.X-ray diffraction (XRD) patterns were obtained using an X-ray diffractometer  engaging nickel-filtered Cu Kα radiation . For testing of transition metal dissolution, 0.1 g of the active materials were immersed in 20 mL of the electrolyte co-solvents (ethylene carbonate (EC):ethyl methyl carbonate (EMC):dimethyl carbonate (DEC) = 3:4:3 = v:v:v) at 50 °C for different durations up to 7 h.The electronic conductivity of the pellets was measured using the two-probe DC method after pelletizing the active powder at 20 kN . Raman spectra were obtained using a Renishaw InVia micro-Raman spectrometer at ambient condition. A 514 nm wavelength Ar-ion laser was used as the excitation source and the incident power was limited to 2 mW to minimize the damage of graphene. The spectral resolution was ~1 cm6) in co-solvents of EC, EMC, and DEC in 3:4:3 = v:v:v with 1 wt% lithium bisborate (LiBOB) and 0.5 wt% vinyl ethylene carbonate (VEC) was used as electrolyte. For testing of cathodes in half-cell, constant current constant voltage (CCCV) mode was used for the 1st cycle at 0.475 mA with cutoff current being 0.0475 mA in the CV period. From the 2nd cycle, constant current (CC) mode was applied at various C-rates (1C = 4.75 mA). For testing of anodes in half-cell, CCCV mode was used for the 1st cycle at 0.27 mA with cutoff current being 0.027 mA in the CV period. From the 2nd cycle, CC mode was applied at various C-rates (1C = 2.7 mA). The mass loadings of NCM cathode and GB anode were 25.0 ± 0.2 and 3.8 ± 0.2 mg cm−2, corresponding to 4.75 and 2.7 mAh cm−2, respectively.In the case of NCM cathodes, a slurry consisting of NCM, super P, GB, and PVDF binder in a weight ratio of 97.0:0.5:1.0:1.5 was coated on an aluminum current collector and dried under vacuum. In the case of GB anode, a slurry consisting of GB and Li-polyacrylic acid (1.1 M) in a weight ratio of 95:5 was coated on a copper current collector and dried under vacuum. Both types of the electrode were then roll-pressed to enhance the interparticle contact. Coin-type half-cells  were prepared by assembling the composite electrode, a separator  and Li foil. 1.3 M lithium hexafluorophosphate . The mass loading of NCM for the full-cell was 12.6 ± 0.2 mg cm−2. The pre-lithiation of the GB anodes was conducted by applying 3.4 mA g−1 in a half-cell containing a Li metal counter electrode until initial Coulombic efficiency reached 93.1%.The performance of the full-cells was evaluated in the voltage range of 2.8–4.2 V using the same electrolyte as in the half-cell tests. The n/p ratio, defined as the total capacity ratio between the anode and cathode, was 1.0, and the areal capacity was set to 2.4 mAh cmAll relevant data in this study are available from the corresponding authors upon request.Supplementary InformationPeer Review File


Chaetomium thermophilum at 2.15 Å resolution and analyze its function by UV RNA-crosslinking (CRAC) and in context of a recent cryo-EM structure of the 90S pre-ribosome. Utp4 consists of two orthogonal and highly basic β-propellers that perfectly fit the EM-data. The Utp4 structure highlights an unusual Velcro-closure of its C-terminal β-propeller as relevant for protein integrity and potentially Utp8 recognition in the context of the pre-ribosome. We provide a first model of the 5'-ETS RNA from the internally hidden 5'-end up to the region that hybridizes to the 3'-hinge sequence of U3 snoRNA and validate a specific Utp4/5'-ETS interaction by CRAC analysis.Eukaryotic ribosome biogenesis begins with the co-transcriptional assembly of the 90S pre-ribosome. The ‘U three protein’ (UTP) complexes and snoRNP particles arrange around the nascent pre-ribosomal RNA chaperoning its folding and further maturation. The earliest event in this hierarchical process is the binding of the UTP-A complex to the 5'-end of the pre-ribosomal RNA (5'-ETS). This oligomeric complex predominantly consists of β-propeller and α-solenoidal proteins. Here we present the structure of the Utp4 subunit from the thermophilic fungus  Chaetomium thermophilum has revealed the overall architecture of the 90S pre-ribosome [The ribosome is the cellular machinery responsible protein synthesis and therefore is vital to cellular function. Assembly in prokaryotes is less complex and to a certain degree spontaneous, while ribosome biogenesis in eukaryotes is a hierarchical and elaborate process. It involves more than 200 non-ribosomal protein factors, which act at different steps of maturation , 2. SeveA number of diseases resulting from defective ribosome biogenesis have been described in the literature , 11 withChaetomium thermophilum (ct) at a resolution of 2.15 Å and analyzed it in the context of a previously published 90S pre-ribosome cryo-EM structure [In order to shed light on the structure-function relationship of Utp4 in early ribosome biogenesis, we solved the crystal structure of Utp4 from the thermophilic fungus Chaetomium thermophilum was described previously [Chaetomium thermophilum  was carried out in E. coli Rosetta 2 (DE3) cells in ZYM5052 medium, grown at 37°C to an OD600 of 1.0. Then, the temperature was dropped to 23°C and the cells were grown further overnight. After harvesting, the cell pellet was mixed with lysis buffer  and lysed in a M-110L Microfluidizer (Microfluidics). Lysate was clarified by centrifugation  and the filtered supernatant was loaded onto a 5 ml HisTrap FF column  previously equilibrated with 10 column volumes (CV) of lysis buffer. The column was further washed with 10 CV of lysis buffer and the protein was eluted using 5 CV of wash buffer containing 500 mM imidazole. Elution fractions containing Utp4 were concentrated and further purified by size exclusion chromatography (SEC). The sample was loaded onto a Superdex 200 26/60 prep grade column  equilibrated with SEC buffer . Se-Met labelled Utp4 was expressed as the native protein using a modified protocol for the inhibition of methionine-biosynthesis with 0.5 mM IPTG induction [Cloning of Utp4 from eviously . Expressnduction .Chaetomium thermophilum UTP-A complex in yeast strain W303  was carried out as previously described using a high copy vector system  that allows GAL1-10 promoter-driven expression of up to six different proteins [6-Utp4, Utp5, Utp8, proteinA-TEV-Utp10, Flag-Utp15, and Utp17), the 5'-ETS (1-587 nt) was transcribed in this yeast strain from a fourth vector (HIS3 marker) using a GAL1 promoter, in which bases 345–472 of the promoter sequence (5'-UTR of the transcribed RNA) have been deleted. All vector plasmids are listed in 600nm of ~2.0, before GAL promoter was induced by addition of 2-fold concentrated galactose-containing medium (2x YPG) at a ratio of 1:1. Cells were harvested after induction for 5 hours by centrifugation at 4000 ×g, washed with dH2O, frozen in liquid nitrogen, and stored at −20°C until use.Heterologous co-expression of the 2, 5% (v/v) glycerol, 0.1% (v/v) NP-40, and 1 mM DTT as previously described [Affinity purification of proteinA-TEV-tagged UTP-A factor Utp10 to isolate the UTP A/5’-ETS complex (co-expressed in yeast) was performed in a TAP buffer containing 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, 1.5 mM MgClescribed , 15.6-Utp4 was performed using the reconstituted and affinity-purified UTP-A/5'-ETS. This RNP carrying untagged Utp4 was used as negative control (‘no His6 tag’). After IgG affinity-purification of the UTP-A complex via proteinA-TEV-Utp10, elution was carried out by TEV cleavage using GST-TEV for 2 hours at 16°C. 500 μL of the corresponding TEV eluates were transferred to 6-well culture plates placed on ice and UV irradiated (254 nm) in the Stratalinker® Crosslinker at 400 mJ/cm2. Cross-linked RNA was digested with 0.4 units of RNace-IT ribonuclease cocktail (Thermo Fisher Scientific). Subsequent Nickel-purification under denaturing conditions and all further steps were carried out as previously described [® III reverse transcription (Thermo Fisher Scientific) was deep sequenced at the DKFZ (Heidelberg) using the Illumina MiSeq system (single-end 50bp). After filtering duplicate reads using the script included in the pyCRAC program [Chaetomium thermophilum using the Novoalign software. Coverage and mutation hotspots were calculated with pyCRAC, plots were generated with R scripts from the pileup files (https://www.r-project.org/).UV-mediated protein-RNA crosslinking and cDNA deep sequencing analysis (CRAC) of His program , reads whttp://www.pymol.org). 5’-ETS modelling was based on previous biochemical restraints [Purified Utp4 was concentrated to 10–20 mg/mL and crystallized in an automated crystallization platform using the sitting drop vapour diffusion method. For structure determination by single anomalous dispersion (SAD) we prepared seleno-methionine labelled protein, which crystallized in a condition containing 5% (w/v) 2-methyl-1,5-pentane-diol (MPD) and 100 mM Tris-HCl pH 8.5). Prior to data collection, crystals were cryo-protected by soaking in mother liquor containing 20% (v/v) ethylene glycol and directly flash-cooled in liquid nitrogen. X-ray diffraction data were collected at the European Synchrotron Radiation Facility (ESRF) beamlines ID14-4 and ID23-2. Data was integrated with XDS  and scalstraints , and wasctUTP-A and ctUTP-B complexes from heterologously expressed components in yeast [ct is always omitted in the following for clarity). UTP-A was also part of our systematic analysis of ribosome biogenesis factors from Chaetomium thermophilum [Chaetomium thermophilum specific C-terminal insertion between β-strands 13C and 13D (residues 717–825) is not resolved in the crystal structure  by another protein (see below).In general, the individual blades of a β-propeller are rather labile arrangements and β-propeller proteins have evolved different ways to keep the blades within a closed ring. Most of the β-propellers circularly permute up to three β-strands of the last blade to the N-terminus of the protein in order to close the ring. This mechanism has been defined as ‘Velcro-closure’ and different combinations  have been described depending on the number of strands provided by each terminus of the β-propeller domain to build up the last blade . For UtpSaccharomyces cerevisiae [Chaetomium thermophilum. Although the 5'-ETS is poorly conserved throughout eukaryotes, a similar fold with several stem-like RNA helices has been predicted for yeast as well as for Chaetomium thermophilum, where it comprises 587 nucleotides [in vitro RNA-protein UV crosslinking and mapped the binding regions within the target RNA by subsequent cDNA deep sequencing (CRAC) [6-tagged Utp4, which was used for in vitro UV crosslinking analysis  . When weg (CRAC) , we founanalysis . Alignmeuch hits . One RNAuch hits .The crystal structure of Utp4 revealed the special orthogonal arrangement of the N-terminal β-propeller 1 in respect to β-propeller 2 and the Velcro-closure of the C-terminal blade 14 by the N-terminal β-strand of Utp4. We therefore asked, if this crystallographic finding is valid in the context of the early 90S pre-ribosome structure as solved recently at 7.3 Å resolution by single particle cryo-EM techniques [ab initio built the 5'-ETS from its very 5'-end to the binding site for the U3 3'-hinge (starting at nucleotide 244) where the RNA forms a double-helix with U3 snoRNA  binds to short Utp4-loops originating from the N-terminal β-propeller 1 . As thesin trans. Previous biochemical data have shown that the Utp4 C-terminal region interacts with Utp8. C-terminal truncations of Utp4 that remove blade 14 result in a loss of the Utp4-Utp8 interaction and the assembly of the 90S pre-ribosome, and in severe growth defects in yeast [Chaetomium thermophilum. Moreover, a single β-strand C-terminal to the extended α-helix is predicted for Utp8 , howevefor Utp8  that wouWhile late assembly and maturation intermediates of the small and large ribosomal subunit have been studied in great detail, relatively little is known about the early co-transcriptional events during 90S pre-ribosome formation. As part of our attempts to decipher the very early steps of ribosome biogenesis we therefore focused on the UTP-A complex and especially on the Utp4 protein. From a previous cryo-EM study [The high resolution crystal structure of the fungal Utp4 protein now reveals the two propellers to be rigidly linked and fixed in a tangential arrangement, as well as an unusual Velcro-closure of the last propeller-blade at a conserved and basic surface patch near the Utp4 termini. Although this unusual parallel complementation of the last blade could have been an artefact of our cloning strategy, it apparently represents a specific protein-binding site for Utp8 within the UTP-A complex as deduced from interaction studies , 25, 26 in vitro UV crosslinking (CRAC). The analysis showed that within the reconstituted 5'-ETS/UTP-A complex, Utp4 binds to 5'-ETS at two distinct sites. The RNA binding region located close to the 5'-end of the 5'-ETS (A53-C96) perfectly fits our model of the 5'-ETS, although it had not been included in first instance as building-restraint. The protein-RNA interaction at nucleotide G66 matches exactly. The first crosslink site is also in agreement to UTP-A CRAC data recently reported in yeast, in which Utp4 was crosslinked to the yeast 5'-ETS around bases 70–90 [in vitro. Within the entire 90S pre-ribosome, the identified second cross-link site is most likely shielded by other components such as the UTP-B, Mpp10 and U3 snoRNP modules. The UTP-B factor Pwp2 has been proposed to bind to the 5'-ETS region that forms a RNA hetero-duplex with the U3 snoRNA [For structural and functional characterization of Utp4 within the UTP-A complex, we first built a model of the 5'-ETS (nucleotides 1 to 243) based on the available cryo-EM density . In ordees 70–90 . In contBased on the previously solved 90S cryo-EM structure , locatesin vivo function. It has been proposed that Utp8 interacts with the C-terminus of Utp4 and that also this interaction is essential for the assembly of the 90S pre-ribosome [An intact Utp4 C-terminus is required for cell growth and maturation of the 18S and 25S rRNAs . In thisribosome . Utp8 onChaetomium thermophilum, although the orientation of the helical stems is different  with the accession number 5N1A. Sequencing data have been deposited at NCBI GEO with the accession number GSE98331.S1 FigA) The β-strand 1D of β-propeller 1 packs against the top of β-propeller 2, making multiple hydrogen bonds. (B) A Chaetomium thermophilum specific insertion in β-propeller 2  is not resolved in the crystal structure.((TIF)Click here for additional data file.S2 Fig(A-B) Multiple sequence alignment of N- and C-terminus of Utp4. (C) Multiple sequence alignment of C-terminus of Utp8 (Nol11 in metazoans), the predicted β-strand is shown in orange. Sequences of Utp4 and Utp8 of Chaetomium thermophilum (ct), Saccharomyces cerevisiae (sc), Xenopus laevis (xl), Homo sapiens (hs), and Mus musculus (mm) were aligned with Clustal Omega. Visualization and overlay of secondary structures was performed with ESPRIPT. Highly conserved residues are highlighted (red).(TIF)Click here for additional data file.S3 Fig(A) Schematic representation of the yeast high-copy plasmid, from which the 5’-ETS rRNA (587 nt) was transcribed including a shortened 5’-UTR (12 nt) and a Cyc1 terminator-derived 3’ UTR (~200 nt). Transcription was driven by the galactose-inducible GAL1 promoter, in which bases 345–472 of the promoter sequence have been deleted. RNA polymerase II start site is indicated by position +1. (B) Overview of the experimental procedure carried out for the CRAC analysis of Utp4. For further details see the (C) Co-expression and affinity purification of the reconstituted UTP-A complex (via proteinA-TEV-ctUtp10) from a yeast strain, in which the 5’-ETS rRNA is transcribed from the construct described in A. Shown are the GST-TEV eluates , analyzed by SDS-PAGE and Coomassie staining. Proteins were labeled according to previous mass spectrometry analysis of highly similar preparations. (D) NiNTA eluates of indicated samples (shown in C) after in vitro UV crosslinking and limited RNase digestion, resolved by SDS-PAGE. Utp4 crosslinked to radiolabelled RNA (marked at the right) was visualized by scanning the membrane in a PhosphorImager.(TIF)Click here for additional data file.S4 Fig(A) The Utp4/5’-ETS complex shown with electron density  as derived from the cryo-EM reconstitution of the entire 90S pre-ribosome complex (1). While the RNA-helices are well defined, the single-stranded regions are only vaguely traceable. (B) The charged Utp4 interaction with the 5’-ETS. Utp4 is highly positively charged  placing the RNA-helices 3 and 4 and single strand regions along both propellers. The single-stranded RNA region between helices 1 and 2 includes nucleotide G66 (magenta) in the propeller interface.(TIF)Click here for additional data file.S5 FigChaetomium thermophilum placed in the cryo-EM density of the pre-90S particle (1) is superposed onto the equivalent structure from yeast (2) (based on Utp4 only). The rudimental-built RNA-helices from yeast 5’-ETS are given (magenta) highlighting the similar overall architecture of the 5’-ETS. The C-terminus of the shorter scUtp8 homolog (rainbow colours) can be connected (dashed lines) to the extended C-terminus of ctUTP8 (orange) responsible for Velcro-closure of ctUTP4.The Utp4/Utp8-C/5’ETS sub-complex of (TIF)Click here for additional data file.S1 Table(DOCX)Click here for additional data file.


Our device combines the superior spin transport properties of graphene with the strong spin–orbit coupling of MoS2 and allows switching of the spin current in the graphene channel between ON and OFF states by tuning the spin absorption into the MoS2 with a gate electrode. Our proposal holds potential for technologically relevant applications such as search engines or pattern recognition circuits, and opens possibilities towards electrical injection of spins into transition metal dichalcogenides and alike materials.Future development in spintronic devices will require an advanced control of spin currents, for example by an electric field. Here we demonstrate an approach that differs from previous proposals such as the Datta and Das modulator, and that is based on a van de Waals heterostructure of atomically thin graphene and semiconducting MoS By forming heterostructures of different layered two-dimensional materials, functional spintronic devices may be built by exploiting the materials' different spin-orbit coupling and spin transport properties. Here, the authors demonstrate a spin switch in a gated structure of graphene and MoS2. The integration of the spin degree of freedom in charge-based electronic devices has revolutionized both sensing and memory capability in microelectronics345For example, carbon-based materials with intrinsic weak SOC, such as organic semiconductors1011121314101316172, the best-known member of that class, has a crossover from an indirect to a direct-gap semiconductor when thinned down to a monolayer (ML)8 in ML and 1 × 106 in multilayers have been found23d-orbitals of the transition metal atoms, offers new possibilities to employ the spin and valley degrees of freedom in TMDs202526Meanwhile, transition metal dichalcogenides (TMDs) have emerged to complement graphene due to their unique optical, spin and valley properties202 in a heterostructure through weak van der Waals (vdW) forces2 layer (spin sink) before its arrival to the ferromagnetic drain terminal. By tuning the gate voltage, we were able to switch the spin current between binary ON and OFF states at temperatures up to 200 K. The current device could be scalable and operative at room temperature, considering both the rapid progress made in chemical vapour deposition of two-dimensional (2D) materials and the theoretical performance of the materials involved.In our work, the combination of graphene with MoS2. An ML graphene flake is identified according to its optical contrast2 flake is transferred above it by all-dry viscoelastic stamping2 electrodes are patterned by electron-beam lithography and evaporated onto the graphene channel, to create lateral spin valves , which enable the injection and detection of pure spin currents in graphene in a non-local geometry10Rnl=Vnl/I, which depends on the relative orientation of the magnetisation of the injecting and detecting Co electrodes, is measured while sweeping the magnetic field B in-plane along the easy axis of the electrodes (see Rnl switches from high (Rp) to low (Rap) value. The spin signal is proportional to the amount of spin current reaching the detector, measured by ΔRnl=Rp−Rap . Rnl as a function of B for different gate voltages (Vg). On application of Vg, the magnitude of the spin signal weakly varies, following the modification of the graphene sheet conductivity , as it is well established in the literatureWe first study the spin transport in a graphene LSV without MoS2 LSV. Rnl of this device, while sweeping B for different values of Vg, where a gradual decrease of the spin signal ΔRnl with Vg can be observed. This behaviour is clearly seen in Rnl is plotted as a function of Vg, showing the decay of ΔRnl towards zero at positive values of Vg, in contrast with the weakly varying spin signal measured in the reference LSV , which are the main control parameters in the spin absorption mechanism. Roughly, they can quantify how easily the spin current flows through each of the materials, in the same way in which one can estimate a charge current flow in parallel electrical resistors. The spin resistances of graphene and MoS2 can be expressed as 2 to be in the range of 10 ps . After identifying the desired few-layer MoS2 flake using optical contrast, it is transferred on top of graphene after slowly removing the viscoelastic stamp.Fabrication of ML graphene samples uses the mechanical exfoliation method initiated in ref. The lateral spin valve is formed following a standard nanofabrication procedure including electron-beam lithography, metal deposition and metal lift-off in acetone. 5 Å of Ti are deposited by electron-beam evaporation and left to oxidize in air for 0.5 h before depositing 35 nm of Co using electron-beam evaporation.2.The measurements are performed in a Physical Property Measurement System by Quantum Design, using a ‘DC reversal' technique with a Keithley 2182, nanovoltmeter and a 6221 current source. A current bias of 10 μA is used unless stated in the text. Gate voltage is applied using a Keithley model 2636. The gate voltage is applied between the back of the doped Si substrate and the grounding electrode. As graphene layer on the bottom is ML, it does not fully screen the gate electric field. Therefore, the gate voltage modulates the charge carrier density in both graphene and the MoSAll relevant data are available from the authors.How to cite this article: Yan, W. et al. A two-dimensional spin field-effect switch. Nat. Commun.7, 13372 doi: 10.1038/ncomms13372 (2016).Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary Figures 1-4, Supplementary Notes 1-3 and Supplementary References


The stability of a resulting toluene solution was also proven by static light scattering measurements over several days. The excellent solubility gives the possibility of an efficient and fast spray application of the functionalized graphene oxide quantum dots to steel surfaces. Hence, the macroscopic friction behavior was investigated with a Thwing-Albert FP-2250 friction tester. A thin film of the dodecyl amine functionalized graphene oxide quantum dots on steel lowered the friction coefficient from 0.17 to 0.11 and revealed a significant corrosion inhibition effect.Dodecyl amine edge functionalized few-layer graphene oxide quantum dots were synthesized in good yields. The covalent functionalization was demonstrated with NMR and AFM-IR. The resulting structure and particle size was measured with AFM and HRTEM. The thermal stability of the compound was investigated and showed a stability of up to 220 °C. The modified graphene oxide quantum dots showed excellent solubility in various organic solvents, including ethers, methanol, toluene,  Typically, lubricants are used to lower the frication of mechanical sliding contacts. Often the lubricant has also the task to prevent corrosion. It has been shown, that functionalized graphene and graphene oxide particles are able to inhibit corrosion4. Lubricants can be separated in liquid and solid lubricants. As liquid lubricants oils are commonly used while for solid lubricants graphite or molybdenum sulfite5 are applied. For many lubricants amines are the basic materials7. Recently, there have been reports that graphene and graphene oxide could be the base for solid and liquid lubricants11.Controlling the friction performance of mechanical contacts like bearings and gears minimize the energy cost and increases the lifetime of everyday mechanical components2-bonded carbon atoms13. It has attracted much attention in recent years due to its exceptional properties such as thermal and mechanical stability as well as electrical and optical activity19. Graphene with an average lateral dimension of 3–30 nm has been applied as graphene quantum dots in photoluminescence experiments24. Larger graphene sheets of up to 100 nm have been also classified as graphene quantum dots in this respect23. In other applications graphene sheets below 100 nm are defined as graphene nanosheets while graphene sheets larger than 100 nm are termed graphene microsheets25. If 2 to 5 graphene layers are dominating, the material has the term few-layer graphene while with up to 10 layers the name multi-layer graphene is used to define the material12. Graphene quantum dots have been so far mainly considered for sensing applications26. In addition, carbon quantum dots have found application in sensing, nanomedicine, photocatalysis and electrocatalysis27.Graphene is a two dimensional, single-atom-thick sheet of hexagonally constructed sp28. Furthermore, while graphene oxide often possess a C/O ratio of 4:1 reduced graphene oxide has often a ratio of 12:125. A further alternative to obtain graphene sheets is to stabilize and increase their solubility via chemical functionalization. The functionalization of graphene, graphene oxide and reduced graphene oxide can influence the behavior of these materials28. Particularly the solubility in different solvents and hence their processability can be increased via functionalization30. Especially the surface functionalization can increase the solubility and also stabilize single graphene sheets. However, this introduces sp3 centers on the graphene sheets, which can influence the behavior of graphene30. In consequence, the graphene sheets incorporate oxygen containing groups  which can be used to modify graphene oxide sheets with small organic molecules like octadecylamine (ODA)31, 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP)32 or 2-(4-aminophenyl)ethanol33. The combination of amines with graphene oxide has shown a good performance in solid lubrification and additives for liquid lubrification35. The common technique for the assembly of the solid lubricants is a layer by layer assembly where the friction coefficient could change36. For example, a friction coefficient of 0.35 for a polymer vs. steel changed to 0.02 under nitrogen with a 300 nm thick polyethyleneimine/graphene oxide film. Under air a higher friction coefficient of 0.10 was observed34.A standard procedure to obtain graphene from graphite is to oxidize the latter to graphene oxide and transform it to reduced graphene oxide. However, reduced graphene oxide does not fully exhibit the behavior of graphene. Reduced graphene oxide sheets have defects in their sheet structure37 and by a modified Hummers method38. In addition, a modified procedure was reported by Haino et al. where graphite was treated with H2SO4 and HNO3 at 120 °C for 24 h which resulted in edge carboxylated graphene quantum dots with a diameter of ca. 21 nm39. Functionalization of the graphene quantum dots with benzyl amine derivatives resulted in material soluble in polar solvents like ethyl acetate or dichloromethane39. Hence, a functionalization or disruption of the surface of the graphene sheets was prevented39. Alternatively, graphene quantum dots can be isolated from coal40. Furthermore, graphene quantum dots were prepared from CX-72 carbon black in high yields and were applied successfully as probes for cellular imaging and have high potential in optoelectronic devices41. The utilization of carboxylic acid functions present in carbon nanoparticles provides a straightforward route to covalent functionalization with amines via the formation of an amide42. The reaction is easy to perform and the resulting amide functions are more resistant to hydrolysis compared to ester functions, since the NHR moiety is even a poorer leaving group than OR44.The behavior of graphene is also dependent on the size of the graphene sheets. If few- or multi-layer graphene is present in the material the solubility decreases. In addition, a decrease of the sheet size will aid to exfoliate graphene sheets. The most common approach to obtain graphene nanosheets from graphite is via electrochemical exfoliation3 centers are present in the sheets the more the original electronic behavior of the graphene nanosheets is preserved.Graphene quantum dots are considered to be the next generation carbon based nanomaterial. This is due to their outstanding physical, chemical and biological properties. In the present study we emphasized that the small size of the graphene quantum dot particles will ensure a good adsorption on the surface, especially with defect and fraction present on the natural surface of steel. In addition, since functionalized graphene oxide quantum dots have not been applied as lubricants so far, we were interested in the functionalization of graphene oxide quantum dots and to influence their behavior as lubricants for steel. In this process, a high solubility of graphene material in different solvents would be beneficial. The ability to predominantly functionalize the edges of graphene sheets leaves the sheet structure intact and the less spFluka AG, Merck AG, Lancaster, Alfa Aesar, Riedel de Haën and Sigma Aldrich. Unless specified otherwise the reagents were further purified by standard procedures. Graphite  and attenuated total reflection (ATR) spectra were measured with VERTEX 700 by Bruker. Raman spectra were recorded by InVia spectroscope in combination with DM2500 M-microscope from Leica Microsystems. GQDs 5 were dissolved in toluene to be dropped on a mica-wafer or carbon-pallets for atomic force microscopy (AFM) by Veeco Dimension Icon from Bruker or for scanning electron microscopy (SEM). To prove the functional groups on the GQDs all products were scanned by thermo gravimetric analyzer-mass (TGA-MS) spectroscopy TGA/SDTA851 by METTLER TOLEDO. X-ray diffraction (XRD) pattern was measured at room temperature using AXS D505 by Bruker. Tribological studies of steel flat samples against coated flat steel samples were performed with a Thwing-Albert FP-2250 Friction/Peel tester with a 2 kg force load cell. The sled has a contact area of 6 cm × 6 cm and a weight of 500 g. The distance between the sled and the load cell is 10.2 cm. The sled was placed on a clean steel surface and moved with a speed of 50 cm/min. The friction coefficient was calculated automatically. Transmission electron microscopy (TEM) was performed at 200 kV with a probe-side Cs-corrected TEM (JEOL JEM-ARM200F), equipped with a cold field emission gun, a post-column energy filter  and a JEOL energy dispersive X-ray spectroscopy (EDS) system. For this purpose, the toluene GOQs 5 suspensions (see below) were drop casted on a carbon coated Cu TEM grid. Even though it is known that at 200 kV graphene is destroyed by knock-on damage, we observed that the GQD were long enough stable in order to investigate them at this acceleration voltage. A similar observation was reported by Wilson and Sloan45.All reagents and solvents were purchased from commercial sources like COOH) 2 were synthesized in the presence of 65% sulfuric acid and 95% nitric acid (3:1)39 from Graphite ), purchased from Sigma Aldrich. The reaction mixture was treated with ultrasonic sound for 3 h to give a homogenous suspension. Afterwards the reaction was stirred at 120 °C for 1 d. The resulting product was neutralized with sodium hydroxide solution and washed with deionized water by use of ultrafiltration  to give GQDCOOH2.Oxidized graphene quantum dots (GQDCOOH2 (5 g) and oxalyl chloride . To slurry the reagents the reaction was treated with ultrasonic sound under reflux for 3 h. Subsequently the suspension was stirred for 3 d under reflux. The residual oxalyl chloride was removed by redestillation to give GQDCOCl3 (5.27 g) as grey powder, which was directly converted to the next step.Under inert gas conditions dry DMF (0.25 mL) was given slowly and dropwise to a reaction mixture of GQDCOCl3 (0.5 g), NEt3 (3 mL), amine 4  and DMAP  were added to dry DMF (10 mL) under nitrogen. The reaction mixture was stirred for 3 d under reflux at 110 °C under an N2-atmosphere. After completion of the reaction dichloromethane (5 mL) was added. The product was washed with acidulated (1 N HCl), bidestilled water (3 × 20 mL) and extracted with diethyl ether (3 × 30 mL) by using hydrophobic amine. Products functionalized with hydrophilic amine were purified by column chromatography using MeOH/CHCl3 as eluent. The degree of amide formation was determined by the content of nitrogen and oxygen by elementary analysis (w.%) , which corresponds to 80 mol%.GQD5 in toluene (0.1 g/L) was performed by using a commercial airbrush  supplied by N2 at 2.5 bar. The steel sheets were coated at a substrate-nozzle distance of 30 cm. Between two spray cycles the steel sheets were dried for 5 min at room temperature. The corrosion behavior was investigated using a steel sample with 20 spray cycles, which was emerged for 1 h in sea water (based on DIN 51358).Commercial Gardobond® cold-rolled steel sheets were cleaned by emerging in ethyl acetate. Before application, the steel sheets were dried for 1 h at room temperature. Thereafter, the spray deposition of the GQD measurements were performed with a Reference 600  potentiostat. A gold wire and a Ag/AgCl electrode were used as counter and reference electrodes, respectively. Impedance data were collected in artificial seawater for a frequency of 0.1 Hz by superimposing a 10 mV AC voltage at open circuit potential for 1 h.2O, 4 g sodium sulfate and 1 g calcium chloride were dissolved in 1 L of water. The mixture was thoroughly stirred and adjusted by dropwise addition of 0.1 N sodium carbonate (Na2CO3) solution.25 g sodium chloride, 11 g magnesium chloride*6 H39. Flaked graphite was treated with H2SO4 and HNO3 at 120 °C for 24 h as depicted in Fig. COOH2 was analyzed by XRD, Raman and AFM (see supporting information). In order to functionalize the carboxylic acid groups at the edges of graphene sheets, the carboxylic acid functions were first transferred into carboxylic acid chloride groups. Therefore, the material was treated with oxalyl chloride as shown in Fig. COCl3 was analyzed (see supporting information). Due to the moisture sensitive carboxylic chloride functions, GQDCOCl3 agglomerated on the AFM waver. Hence GQDCOCl3 was directly used in the subsequent step. The as-prepared material was treated directly with dodecyl amine 4 in order to form the desired carboxylic acid amides  were prepared according to a modified literature proceduredes Fig. . With do2, 3 and 5 see supporting information). The GQD dodecyl amine compound 5 showed a higher thermal resistance than pure dodecyl amine46. Due to the high solubility of the material in different solvents (for pictures of solutions with different solvents see supporting information) an 1H-NMR spectrum in deuterated toluene showed the formation of an amide group with a signal at 7.9 ppm in deuterated toluene  at 1020 cm−1 49, amide I at 1650 cm−1 49, amide II at 1540 cm−1 49, amide III at 1260 cm−1 ν (CH2), and a C=O stretch at 1720 cm−1. .For the identification of the sucessful amide formation an additional atomic force microscope infrared-spectroscopy measurment was performed Fig. . It show5 was investigated via HRTEM. An overview of the sample is shown in Fig. In addition, GQDs 2 hybridized carbon in graphene and smaller bond lengths reported for C=C bonds at lower hybridization50. The thickness of individual GQDs was determined by energy-filtered TEM using the log-ratio method and electron mean free path estimations according to the Malis model51 to be 2–3 nm.This is further supported by a HRTEM structure determination depicted in Fig. 5, the latter were dissolved in toluene and the resulting solution was observed for several days with static light scattering . The result is depicted in Fig. 5 coated steel is about an order of magnitude higher than that of uncoated steel. In both case the corrosion resistance slightly increases over time most probably based on the formation of corrosion products that slow down the interfacial transfer reactions. The impedance measurements thereby support the qualitative observations of the seawater immersion test52.Based on the time-dependent measurements of the impedance at 0.1 Hz Fig. , it gets5 applied as a lubricant can inhibit tribo-corrosion. The protecting mechanism is resulting from a barrier property of the dodecyl amine functionalized GQDs 5 film. Taking into consideration that the film thickness is at 20 spray cycles only 17 nm  the resulting effect is remarkable. Often a higher coating thickness is found with other carbon based coatings based on graphite10.Hence, 10. In addition, a better friction coefficient was observed compared to alkylated graphene oxide systems in combination with oil11. The presented results will help to further improve the development of tribo-corrosion inhibiting lubricant systems based on graphene derivatives.Graphene quantum dots (GQDs) and dodecyl amine functionalized GQDs have been prepared and investigated as lubricant. The resulting modified GQDs showed very good solubilities in numerous organic solvents, including ethers, methanol, n-hexane, heptane, xylene, dichloromethane and toluene. The good solubility provided the possibility of an efficient and fast spray application of the functionalized GQDs to a steel surface. In the presented work, it was possible to show with different methods that the successful covalent modification of GQDs with dodecyl amine was achieved. The resulting particles had an average size between 5 and 40 nm. The functionalized GQDs could be applied in spray coating to create a thin lubricant film on steel. The resulting lubricant film reduced the friction coefficient from 0.17 to 0.11 on the macro scale and it was shown for the first time that this graphene quantum dot based material has a significant corrosion inhibition effect. Compared to unfunctionalized graphene oxide, the functionalisation caused a significant enhancement of the lubricantSupplementary Information


This paper describes the development of a graphene-based dry flexible electrocardiography (ECG) electrode and a portable wireless ECG measurement system. First, graphene films on polyethylene terephthalate (PET) substrates and graphene paper were used to construct the ECG electrode. Then, a graphene textile was synthesized for the fabrication of a wearable ECG monitoring system. The structure and the electrical properties of the graphene electrodes were evaluated using Raman spectroscopy, scanning electron microscopy (SEM), and alternating current impedance spectroscopy. ECG signals were then collected from healthy subjects using the developed graphene electrode and portable measurement system. The results show that the graphene electrode was able to acquire the typical characteristics and features of human ECG signals with a high signal-to-noise (SNR) ratio in different states of motion. A week-long continuous wearability test showed no degradation in the ECG signal quality over time. The graphene-based flexible electrode demonstrates comfortability, good biocompatibility, and high electrophysiological detection sensitivity. The graphene electrode also combines the potential for use in long-term wearable dynamic cardiac activity monitoring systems with convenience and comfort for use in home health care of elderly and high-risk adults. Cardiovascular disease, which includes both coronary heart disease and stroke, is one of the most prevalent causes of death worldwide. In addition to these fatal cases, at least 20 million people experience nonfatal heart attacks and strokes every year; many of these people subsequently require prolonged and costly medical care ,2. ElectFollowing the development of flexible and stretchable electronics, alternative electrodes that do not require electrolytic gel (referred to as active dry electrodes) have been reported by many groups ,14,15,16In this study, flexible graphene textile was synthesised by the reduction of graphene oxide with the help of vacuum filtration to improve the amount and degree of adsorption, and then the graphene textile was used to construct electrodes for long-term wearable ECG monitoring applications. The structural properties of graphene were first characterized by Raman spectroscopy and scanning electron microscopy (SEM), and then the electrical properties of the designed electrode were evaluated by diverse testing based on alternating current (AC) impedance spectroscopy and connect impedance with skin, according to frequency changes. Subsequently, we measured ECG signals in different states of human body motion and studied the feasibility of long-term monitoring through continuous measurements. The experimental result and statistical comparative study demonstrates the potential usefulness of the proposed graphene electrodes for routine electrophysiological activity monitoring of the heart and other vital organs.Numerous methods can be used to fabricate graphene, including chemical vapor deposition (CVD) , organicRaman spectroscopy and SEM are widely used characterization methods for examination of the microstructures of materials. Raman spectroscopy provides information about the characteristic vibrational states, while SEM gives surface profile information. In this paper, the Raman spectra of graphene electrodes were measured using a Horiba Jobin Yvon confocal LabRAM HR800 spectrometer with an excitation wavelength of 532 nm, and the SEM was performed using a Hitachi TM3030 electron microscope with an accelerating voltage range of 3–15 kV. The electrical properties of the ECG electrodes were characterized via electrochemical impedance spectroscopy (EIS) measurements that were performed using a CS350 electrochemical workstation , which worked with a sweeping frequency range from 50 mHz to 10 Hz and an AC perturbation of 10 mV. Skin–electrode contact impedance measurement has always been of interest due to the desire to prove the reliability of the collected biopotential . Here, tFor performance evaluation of the graphene electrode, ECG signals were measured in different human body motion states in 24-year-old male volunteers. Two electrodes were fixed on the left and right sides of the ribcage of each test subject, and the reference ground was located in their lower right abdomen. To ensure similar test conditions for comparison, these electrodes were positioned in the same locations for every measurement. The resting-state ECG signals were measured first, and then the motion artifacts that result from walking and swinging of the subject’s arms were investigated. To study the effects of moisture on the quality of the ECG signals, measurements were also taken after exercise. Finally, the ECG signals were measured using the graphene textile electrodes over a period of one week to evaluate their long-term monitoring capabilities.The Raman spectra of graphene for various thicknesses are shown in hickness ,29, and In the graphene textile and the graphene paper, the Raman spectra show two main peaks, the G- and D-peaks, which lie at approximately 1580 cmc G band . CompareThe morphological studies of the graphene samples performed using SEM are shown in Bode plots of the graphene electrodes and of commercial Ag/AgCl electrodes within the 0.05 to 10 Hz frequency range are presented in To estimate the ECG detection performances of the different kinds of graphene electrode, typical ECG signals are collected, as shown in When compared with graphene–PET and graphene paper, the graphene textile electrode shows the best flexibility and assembly characteristics, and thus it was selected for further study in terms of its performance in daily ECG monitoring applications. Skin–electrode contact impedance directly influenced the reliability of collected signals, low contact impedance resulting in less noise and a higher quality ECG signal. Here, we measured the skin–electrode contact impedance of graphene textile with different contact force, and compared that to standard Ag/AgCl electrode. Four examples of motion artifacts are shown in Furthermore, we compared the performance of graphene textile electrode with commercial Ag/AgCl electrode at different motion states, the peak-to-peak amplitude (P–P), heart rate, SNRs, and standard deviation (SD) of collected ECG signals are summarized in In order to assess the performance in long-term measurement, the ECG signal was collected over seven days of continuous wear of the graphene textile electrode. The waveforms of ECG signals in days 1, 3, 5, and 7 are displayed in Mobile health care systems have increased in popularity because of their noninvasive features and convenience for use in daily life. In this study, we aimed to develop wearable flexible electrodes for daily ECG monitoring, which would be very helpful in the detection of sudden onset heart disease, especially in elderly patients. Electrodes that are highly sensitive, comfortable, and offer biological compatibility and persistence are essential components for daily ECG monitoring systems. The results presented here have demonstrated that the proposed graphene-based electrode offers sensitivity comparable to that of commercial Ag/AgCl electrodes; this research also indicates opportunities to transfer graphene for use in other biological applications, such as electroencephalography (EEG) and electromyography (EMG) detection.However, one challenge that remains for the use of graphene materials in daily ECG monitoring is their intrinsically high hydrophobicity, which might lead to a weak binding force to the substrate and high impedance between the graphene and electrolyte surfaces. In our early study of graphene electrodes on a soft elastic PDMS substrate, the graphene films were found to fall off easily, and they showed much higher resistance due to broken parts of the graphene structure. In this study, graphene was adsorbed on polyester fibers using a vacuum suction filter; the intrinsic internal resistance of the graphene textile reached several megaohms, indicating that the adsorption amount and the combination degree must be further improved to enhance the detection sensitivity and the frictional resistance. We will apply our efforts to the selection of a more suitable substrate, and will increase the binding force between the graphene films and the substrate by introducing molecules with grafting chains. With regard to toxicity, carbon is commonplace and has a stable structure; previous studies have demonstrated the biological compatibility of carbon group elements, including carbon nanotubes and graphene , and thuIn this paper, we have fabricated graphene-based electrodes and a corresponding wireless ECG collection system. The results demonstrated that ECG signal recording can be carried out using a flexible graphene electrode with high SNR. The graphene electrode provides effective electrical performance, high flexibility, satisfactory biocompatibility and wearability, and offers detection capabilities in various states of motion. The design presented here provides a potential electrode structure for long-term wearable monitoring, and offers convenience and comfort for home health care management of the elderly population, with collection and computer display of the results performed via wireless communication using the developed graphene electrode.